Abstract:
The present invention provides a movable load bearing structure with a surface that includes antimicrobial agents capable of eliminating, preventing, retarding or minimizing the growth of microbes and also minimizing cross-contamination when the load bearing structure is being reused for cargos that differ from a previously transported cargo, for example, different food types, such as poultry, fresh vegetables, and fresh fruit. The load bearing structure may be a dunnage platform or a container for storing and/or shipping cargo.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the priority and benefit of U.S. provisional patent application Ser. No. 61/508,425, filed Jul. 15, 2011, entitled “CLIMATE CONTROL CARGO CONTAINER FOR STORING, TRANSPORTING AND PRESERVING CARGO”; U.S. provisional patent application Ser. No. 61/551,323, filed Oct. 25 2011, entitled “CARGO CONTAINER FOR STORING AND TRANSPORTING CARGO”; U.S. provisional patent application Ser. No. 61/551,340, filed Oct. 25 2011, entitled “A LOAD BEARING STRUCTURE HAVING ANTIMICROBIAL PROPERTIES”; and U.S. provisional patent application Ser. No. 61/590,323, filed Jan. 24, 2012, entitled “SYSTEM FOR FACILITATING SECURITY CHECK OF SHIPMENT OF CARGO”; the contents of all of which are hereby incorporated by reference in their entirety. 
         [0002]    The present application includes claims that may be related to the claims of co-pending U.S. patent application Ser. No. 12/______, entitled “CARGO CONTAINER FOR STORING AND TRANSPORTING CARGO”; co-pending U.S. patent application Ser. No. 12/______, entitled “CLIMATE CONTROL CARGO CONTAINER FOR STORING, TRANSPORTING AND PRESERVING CARGO”; and co-pending U.S. patent application Ser. No. 12/______, entitled “SYSTEM FOR FACILITATING SECURITY CHECK OF SHIPMENT OF CARGO”; the contents of all of which are hereby incorporated by reference in their entirety. 
     
    
     FIELD OF THE INVENTION 
       [0003]    This invention is in the general field of load-bearing structure and, more particularly, a load bearing structure having antimicrobial properties. 
       BACKGROUND OF THE INVENTION 
       [0004]    A shipping pallet is a well known load-bearing, moveable platform whereon articles are placed for shipment. The pallet usually is loaded with a multiplicity of items, such as cartons or boxes. The loaded pallet is movable with either a pallet truck or a forklift. 
         [0005]    The adoption of International Standardized Phytosanitary Monitoring (ISPM)-15 for wood packaging material (WPM) requires kiln dry treatment of all wood used in shipping crates and dunnage platforms (pallets). The United States in cooperation with Mexico and Canada began enforcement of the ISPM 15 standard on Sep. 16, 2005. The North American Plant Protection Organization (NAPPO) strategy for enhanced enforcement will be conducted in three phases. Phase 1, Sep. 16, 2005 through Jan. 31, 2006, call for the implementation of an informed compliance via account managers and notices posted in connection with cargo that contains noncompliant WPM. Phase 2, Feb. 1, 2006 through Jul. 4, 2006, calls for rejection of violative crates and pallets through re-exportation from North America. Informed compliance via account managers and notices posted in cargo with other types of non-compliant WPM continues to remain enforce. Phase 3, Jul. 5, 2006, involves full enforcement on all articles of regulated WPM entering North America. Non-compliant regulated WPM will not be allowed to enter the United States. The adoption of ISPM-15 reflects the growing concern among nations about wood shipping products enabling the importation of wood-boring insects, including the Asian Long horned Beetle, the Asian Cerambycid Beetle, the Pine Wood Nematode, the Pine Wilt Nematode and the Anoplophora Glapripwnnis. 
         [0006]    Thus the wooden dunnage platform has become unattractive for the international shipment of products. Further, the wooden surface is not sanitary since it potentially can harbor in addition to insects, mould and bacteria. Thus, the wooden crate is generally ill-suited for the shipment of foodstuffs and other produce requiring sanitary conditions. In addition, with the concern for carbon emission, lighter weight platforms and containers are more desirable. 
         [0007]    Plastic dunnage platforms or pallets are known, see U.S. Pat. No. 3,915,089 to Nania, and U.S. Pat. No. 6,216,608 to Woods et al., which are herein incorporated by reference in their entirety. Thermoplastic molded dunnage platforms are known, see for example U.S. Pat. Nos. 6,786,992, 7,128,797, 7,927,677, 7,611,596, 7,923,087, and 7,544,262, to Dummett, which is herein incorporated by reference in its entirety, discloses applying thermoplastic sheets to a preformed rigid structure for manufacturing dunnage platforms. 
         [0008]    While the plastic surface of the plastic pallet obviates some of the sanitary problems with wood pallets, because of the required repetitive use the surface can become unsanitary. As a consequence when used for the shipment of foodstuffs and other produce requiring sanitary conditions, the high cost of the plastic pallet requires that the plastic surface be cleaned and kept clean prior to use. 
         [0009]    Some wood pallet manufacturers have attempted to produce a more sanitary surface by combining foam with wooden surfaces. These dunnage platforms still suffer a number of disadvantages including their weight, the presence of wood requiring kiln treatment and the possibility of the foam being stripped away to expose the wood surface 
       SUMMARY OF THE INVENTION 
       [0010]    The present invention relates to a load bearing structure that includes antimicrobial agents capable of eliminating, preventing, retarding or minimizing the growth of microbes and also minimizing cross-contamination when the structure is being reused for cargos that are different from previous cargo, for example, different food types, such as poultry, fresh vegetables, and fresh fruits. The load bearing structure may also be suitable for use directly in clean rooms where cargo is being made without additional steps of transferring the cargo to a load bearing structure after the cargo leaves the clean room. The products may be placed directly on the structure after manufacture, thus eliminating steps, saving time, minimizing manpower or robotics, or risk of contamination or damage. 
         [0011]    In one embodiment of the invention, a movable loading bearing structure is a dunnage platform having a top side, and a bottom side joined together to each other by a width. The platform includes a light weight polymeric core and a polymeric layer substantially covering the core. The layer may have anti-microbial properties described above. In one aspect, the layer may cover the top side and a portion of the width of the core. In another aspect, the layer may cover the top and bottom side and substantially all of the width of the core. The polymer layer may be a polymeric sheet or a sprayed coating. In one exemplary embodiment, at least one antimicrobial agent having some surface activity may be added to the material used for making the sheet or coating. The antimicrobial agent may be in powder form or in liquid form. In another exemplary embodiment, at least one antimicrobial agent having some surface activity may be coated onto the exposed surface or surfaces of the sheet or coating. The antimicrobial agent may be in powder form or in liquid form. 
         [0012]    In another embodiment of the invention, a movable load bearing structure is a dunnage platform having a top side, and a bottom side joined together to each other by a width. The platform includes a light weight polymeric core made by injecting a polymer composition into a mold to form the core and after removing the core from the mold, spraying a polymer coating on the polymer core. For example, liquid polyurethane may be injected into a mold to form a polyurethane core which may or may not contain grooves, protrusions and/or pockets which after curing is removed from the mold and sprayed with polyurea to form one or more of the dunnage platforms. In one embodiment, the polymer coating may include an antimicrobial agent having some surface activity therein. In another embodiment, an antimicrobial coating having some surface activity may be applied to at least one of the exposed surfaces of the dunnage platform after formation of the sprayed coating. The antimicrobial agent may be in powder form or in liquid form. 
         [0013]    In a further embodiment of the invention, a movable load bearing structure may be in the form of a container assembled from a plurality of loading bearing structures such as dunnage platforms, each having a light weight polymeric core and a high impact polymeric sheet substantially covering the core. The dunnage platforms may be also made by injecting a polymer into a mold to form the core and after removing the core from the mold, spraying a polymer coating on the polymer core. 
         [0014]    In one embodiment, each of the walls, top and base of the container may be made of a light weight core substantially covered with a polymeric layer on at least one of its surfaces to form a load bearing structure having a width as noted above. The layer may have anti-microbial properties described above. In one aspect, the polymer layer may cover the top side and a portion of the width of the core. In another aspect, the polymer layer may cover the top and bottom side and substantially all of the width of the core. In one exemplary embodiment, at least one antimicrobial agent having some surface activity may be added to the material used for making the polymeric layer, for example, a high impact polymeric sheet. The antimicrobial agent may be in powder form or in liquid form. In another exemplary embodiment, at least one antimicrobial agent having some surface activity may be coated onto the exposed surface or surfaces of the sheet. The antimicrobial agent may be in powder form or in liquid form. 
         [0015]    In another embodiment, a structural metal mesh may be inserted into the core to resist piercing of the surface. The polymeric layer may have anti-microbial properties described above. In one aspect, the polymeric layer, for example, a high impact sheet, may cover the top side and a portion of the width of the core. In another aspect, the polymeric layer, for example, a high impact sheet, may cover the top and bottom side and substantially all of the width of the core. In one exemplary embodiment, at least one antimicrobial agent having some surface activity may be added to the material used for making the layer. The antimicrobial agent may be in powder form or in liquid form. In another exemplary embodiment, at least one antimicrobial agent having some surface activity may be coated onto the exposed surface or surfaces of the layer. The antimicrobial agent may be in powder form or in liquid form. 
         [0016]    In yet a further embodiment of the invention, a load bearing structure, for example, an easily movable structure, may be in the form of a container assembled from a plurality of load bearing structures such as dunnage platforms, each having one or more of the walls, top and base portions having a light weight polymeric core that may be made by injecting a polymer into a mold to form the core and after removing the core from the mold spraying a polymer coating on the polymer core. For example, liquid polyurethane may be injected into a mold to form a polyurethane core containing grooves, protrusions and/or pockets which after curing is removed from the mold and sprayed with polyurea to form one or more of the load bearing structures. In one embodiment, the polymer coating may include an antimicrobial agent therein. In another embodiment, an antimicrobial coating may be applied to at least one of the exposed surfaces of the dunnage platform after formation of the polymeric coating. The antimicrobial agent may be in powder form or in liquid form. 
         [0017]    In a still further embodiment of the invention, a container that is light weight, strong, and assembled from a plurality of movable load bearing structures discussed above, having antimicrobial properties, and/or made of a fire retardant material and ultra violet light barrier is disclosed. 
         [0018]    In one embodiment, a porous surface, which may be a porous sheet substrate or surface of the core, for example, an expanded polystyrene core or polyurethane core, may be impregnated with a water based antimicrobial composition, having at least one polymeric carrier that may be in the form of an emulsion or dispersion and at least one substantially non-leaching antimicrobial component that is substantially free of environmentally hazardous material. The porous surface may or may not be overcoated or protected with a film layer after being impregnated with the antimicrobial composition. 
         [0019]    In another embodiment, a porous surface, which may be a porous sheet substrate may be impregnated with a water based antimicrobial composition, having at least one polymeric carrier that may be in the form of an emulsion or dispersion and at least one surface active antimicrobial component that is substantially free of environmentally hazardous material. 
         [0020]    In yet another embodiment, a non-porous sheet substrate may be coated with a water based antimicrobial composition, having at least one polymeric carrier that may be in the form of an emulsion or dispersion and at least one substantially non-leaching antimicrobial component that is substantially free of environmentally hazardous material. 
         [0021]    For load bearing structures having one thermoplastic sheet over the core thereon, the exposed surfaces may be porous, as noted above. The porous material may be impregnated with a water based antimicrobial composition, also as mentioned above, making the surface non-porous. 
         [0022]    In some embodiments, the surfaces of the porous materials impregnated with an antimicrobial composition may be non-porous after drying or setting and may perform as if it has been coated or covered with a thermoplastic sheet or layer mentioned above. 
         [0023]    The same emulsion or dispersion mentioned above may also be coated onto the exposed surfaces of load bearing structures having two thermoplastic sheets over the core thereon. 
         [0024]    Examples of antimicrobial component that is substantially free of environmentally hazardous material may include sodium omadine, sodium borate, zinc omadine, zinc borate, calcium borate, barium metaborate, iodo alkynyl alkyl carbamates, diiodomethyl-p-tolylsulfone, 2-4-thiazolyl-benzimidaxole, 2-n-octyl-4-isothiazolin-3-one, zinc dimethyldithiocarbamate, zinc 2-mercaptobenzothiazole, potassium n-hydroxymethyl-n-methyldithiscarbamate, sodium 2-mercaptobenzothiazole, 5-hydroxyemthoxymethyl-1-aza-3,7-dioxa-bicyclooctane, 2,3,5,6-tetra-chloro-4-pyridine, zinc 2-pyridinethiol-1-oxide and N-trichloromethylthiophthalimide, tetrachloroisophthalonitrile, deltamethrin, fipronil, bifenthrin, chlorfenapyr, imidacloprid, and mixtures thereof. For use in facilitating security check, metallic compounds are not used. 
         [0025]    Non-leaching antimicrobial materials are for example, materials with a very low volatility and very low water solubility such that it would only leach out to the extent sufficient to maintain an effective and uniform concentration throughout the exposed surface(s) of the antimicrobial article when its concentration thereon is reduced due to its action against microorganisms. In other words, the antimicrobial component is selected not to be fugitive or migrating once being incorporated into the impregnated article, but to have a very low water solubility so that it could maintain an equilibrium concentration throughout the article on its surface(s) whenever the concentration reduction occurs thereon due to the attack of the microbes. The antimicrobial component may have a water solubility of, for example, from about 0.10 PPM to about 1.0 wt %, depending on each individual antimicrobial component. 
         [0026]    The porous sheeting material may include various woven or non-woven fiberglass, Brattice cloth, cotton and other fabrics, heavy weight paper, light weight wire mesh, ceramic cloths, or polymeric material, such as, some synthetics, e.g., various woven or non-woven polyester, polypropylene, polyethylene, Nylon, synthetic fiber blend, etc. an emulsion or dispersion of a film-forming polymer that has a glass transition temperature (Tg) of from about −70.degree. F. (about −57.degree. C.) to about 140.degree. F. (about 60.degree. C.). Wire mesh and other metallic materials may not suitable for facilitating security check. 
         [0027]    For example, the polymeric emulsion or dispersion has a medium particle size of from about 0.10 micron to about 4.0 micron. Examples of useful polymeric emulsion or dispersion includes, such as, emulsions or dispersions of styrene acrylic copolymers, such as Acronal S702 from BASF, Ucar 376 from Union Carbide, and Res 3077 from Rohm &amp; Haas; styrene butadiene block copolymers, such as, DL 313 NA from Dow Chemical, ND-565 and ND-422 from BASF, and Rovene 6105 from Mallard Creek Polymers; ethylene vinyl acetate copolymers, such as Airflex 400/A405/460 from Air Products and Elvace 1875 from Reichhold Chemicals; polyvinyl acetate homopolymer, such as PD-316 from H.B. Fuller Company, and Airflex XX-220/230 from Air Products; acrylate-acrylonitrile copolymers, such as Synthemuls, various grades from Reichhold Chemicals; vinyl acetate-vinyl chloride ethylene copolymers, such as Airflex 728 from Air Products; ethylene vinyl acetate butyl acrylate terpolymers, such as Airflex 809 from Air Products; butadiene-acrylonitrile copolymers, such as Tylac, various grades from Reichhold Chemical; vinyl acrylic-vinyl chloride, such as Haloflex 563 from Zeneca Resins; vinylidene chloride-acrylic-vinyl chloride copolymers, such as Vycar 660X14 and Vycar 460X46 from B.F. Goodrich; chloroprene polymers and copolymers, such as DuPont Neoprene latex 115, 400, 654 and 750 from DuPont; water-borne urethane polymers, such as Neo Rez R-962, 967 and 972 from Zeneca Resins, and mixtures thereof. 
         [0028]    The porous or non-porous sheet substrate may be useful as an embodiment of the bag-like enclosure. The protective or overcoating layer may also be moisture impervious and/or breathable. Examples of impervious layers may be found in U.S. Pat. No. 7,699,826, as disclosed above, the content of which is incorporated hereby by reference in its entirety. Breathable packaging material, as disclosed above, may be a multicomponent film structure, such as that disclosed in U.S. Pat. No. 5,447,783, or a non-woven fabric laminate, such as that disclosed in U.S. Pat. No. 5.482,765, or a breathable film layer as disclosed in U.S. Pat. No. 6,432,547, the contents of which are hereby incorporated by reference in its entirety. Biodegradable, breathable enclosures may also be useful and example is disclosed in U.S. Pat. No. 7,910,645, the contents of all of which are hereby incorporated by reference in their entirety. 
         [0029]    In any of the above embodiment, a zinc oxide material may also be included into the coating. 
         [0030]    In yet another embodiment of the invention, the container may include two halves, each having a substantially L-shaped cross-section. In one embodiment of the invention, the container may include two identical or mirror images substantially L-shaped cross-section halves each having at least two walls and a base or top component, each of the components having corresponding interlocking features to be mated together to form a container having for example, a closed enclosure therein. 
         [0031]    One of the load bearing structure or dunnage platform of the container may also have a plurality of feet extending from the bottom side of the structure. 
         [0032]    In still another embodiment of the invention, the container includes two halves, such as clam shell halves, in mirror images, each having at least two walls and a base or top component, each of the components having corresponding interlocking features to be mated together to form a container having for example, a closed enclosure therein. Each of the halves having an inner surface and an outer surface joined by a width. The footprint of the knock-down or collapsed container is not larger than the footprint of each of the substantially L-shaped cross-section halves or clam shell halves. 
         [0033]    In one embodiment, each half is made of an inner light weight core covered by at least one layer of strengthened coating. The layer of strengthened coating includes antimicrobial properties. In another embodiment, a structural metal mesh may be inserted into the core to resist piercing of the surface. The layer of strengthened coating includes antimicrobial properties. In a further embodiment, one or more of the substantially L-shaped cross-section halves may be made by injecting a polymer into a mold to form the core and after removing the core from the mold, spraying a polymer coating on the polymer core. For example, liquid polyurethane may be injected into a mold to form a polyurethane core containing grooves and pockets which after curing may be removed from the mold and sprayed with polyurea to form one or more of the load bearing structure and the half enclosures. At least some of the exposed surfaces of the container may have antimicrobial properties, for example, an antimicrobial agent incorporated into the material of the surface layer or an antimicrobial coating may be present on the exposed surfaces of the inside and/or outside of the container. 
         [0034]    The dunnage platforms useful for assembling may include interconnecting features which mate together to form a container. 
         [0035]    According to one embodiment, the container may include an enclosure having one undivided internal compartment. According to another embodiment, the container may include an enclosure having more than one internal compartments. In one aspect, the interior may have dividers molded into the side of the component structures. In another aspect, the dividers may be added to the container to form separate compartments. Channels or depressions may be present or molded into the components of the container to allow for placement of external dividers to adjust the size of the compartments. 
         [0036]    According to one embodiment, features may be present or molded into the components of the container for placement of cargo or placement of other components for more secure location of cargo. According to another embodiment, the channels or depressions mentioned above may be used to locate the features. 
         [0037]    In one aspect, the containers may be made of the size and shape to accommodate the cargo. In another aspect, the cargo may be contained in its own packaging and then inserted into the container. In a further aspect, features may be located in the container to aid in accommodating the cargo. 
         [0038]    The present invention also relates to a load bearing structure for use in clean rooms for the manufacturing of electronic parts, snacks, food products or similar products that have to be kept clean from dust, dirt or microbes. The products are placed directly on or into the structure after making, thus eliminating steps, saving time, minimizing manpower or robotics, or risk of contamination or damage. 
         [0039]    The present invention further relates to containers for shipping and/or storage of cargo in which the climate within the container is controlled. 
         [0040]    According to the present invention, the polymeric core, for example, may be a closed cell foam core such as an expanded polystyrene core with a region proximal to its surface that is combined with a high impact polymeric sheet, for example, a polystyrene sheet, by heat and pressure. For a polyurethane core, the core may be covered with a sprayed coating of, for example, polyurea. In one exemplary embodiment, at least one antimicrobial agent having some surface activity may be added to the material used for making the sheet or coating. The antimicrobial agent may be in powder form or in liquid form. In another exemplary embodiment, at least one antimicrobial agent having some surface activity may be coated onto at least one of the exposed surfaces of the sheet or coating. The antimicrobial agent may be in powder form or in liquid form. 
         [0041]    Under heat and pressure, the strength of the combination of the core and polymeric sheet is substantially increased, for example, in the order of at least five times; more for example, in the order of at least ten times that of the core before the combination. For spray coating, no additional heat and pressure application may be needed after coating. 
         [0042]    This increase in strength allows the loading bearing structures, such as a dunnage platform, to carry loads comparable to loads carried by a wooden pallet, for example, which weighs many times more. In addition to having antimicrobial properties, the dunnage platform of the present invention also does not support insect life and does not have splinters and nails that may cause injury. 
         [0043]    In any of the embodiments, the antimicrobial properties may be generated from materials including chemical anti-microbial materials or compounds that are capable of being substantially permanently bonded, at least for a period such as the useful life of the load bearing structures, either when at least one antimicrobial agent is added to the material used for making the polymeric layer, for example, a sheet or sprayed coating mentioned above, or when at least one antimicrobial agent having some surface activity is coated onto the exposed surface of the polymeric layer, for example, sheet or sprayed coating mentioned above; or maintain their anti-microbial effects when at least one antimicrobial agent is coated with the aid of coating agents, onto the exposed surface of the polymeric layer, for example, sheet or sprayed coating mentioned above. In one example, the chemicals may be deposited on the surface of the loading bearing structures by covalent linkage. 
         [0044]    When the antimicrobial agent or agents are incorporated in the material used in making the polymeric layer, for example, a sheet or sprayed coating, the agent or agents maybe dispersed directly into the material, or with the aid of an appropriate carrier, for example, a binding agent, a solvent, or a suitable polymer mixing aid. These carriers may also be useful for coating aids mentioned above. Effective binding agents are those that do not interfere with the antimicrobial activities of the antimicrobial agent. In one embodiment, when the anti-microbial agent is incorporated into the material used either for making the polymeric layer, for example, a sheet or sprayed coating mentioned above, the antimicrobial agent maybe master batch in the material, or an appropriate carrier at a higher concentration prior to adding to the material for making the polymeric layer, for example, a sheet or sprayed coating in desired proportions. In another embodiment, the antimicrobial agent may be added directly to the material for making the polymeric layer, for example, a sheet or sprayed coating without the intermediate step. 
         [0045]    In other embodiments, the antimicrobial agents, either in coatings or incorporated into the materials for making the polymeric layer, for example, sheets or surface coatings, may include chemical antimicrobial materials or compounds that may be deposited in a non-permanent manner such that they may slowly dissolve, slowly leach or otherwise deliver antimicrobial substances during use. The material may be adequately incorporated, though temporarily and/or in sufficient amounts to last at least for a period such as the useful life of the load bearing structures, either when at least one antimicrobial agent is added to the material used for making the polymeric layer, for example, a sheet or sprayed coating mentioned above, or when at least one antimicrobial agent is coated onto the exposed surface of polymeric layer, for example, the sheet or sprayed coating mentioned above; or maintain their anti-microbial effects when at least one antimicrobial agent is coated with the aid of coating agents, onto the exposed surface of the polymeric layer, for example, a sheet or sprayed coating mentioned above. The suitable agent or agents are those that tend to slowly migrate or non-leaching, as defined herein, to the surfaces to provide antimicrobial properties to the surfaces. 
         [0046]    In still other embodiments, the antimicrobial agent either in coatings or incorporated into the material used for making the polymeric layer, for example, sheets or sprayed coatings may include sources of anti-microbial agents which may leach and/or release agents in a moist environment or upon contact with moisture. These sources may be incorporated into the substrate materials used for manufacturing the polymeric layer, for example, sheet mentioned above, or included in the coatings spray coated on the exposed surfaces of the core or sheet. Incorporation of these sources may be especially suited to polymeric substrates. 
         [0047]    Chemical antimicrobial materials or compounds may include a variety of substances including, but not limited to antibiotics, antimycotics, general antimicrobial agents, quaternary ammonium cations, a source of metal ions such as metal ion generating materials, triclosan, chlorhexidine or any other materials capable of generating an antimicrobial effect, and/or any other appropriate compound or mixtures thereof. 
         [0048]    In yet further embodiments, antimicrobial activity may be achieved by utilizing the antimicrobial properties of various metals, especially transition metals which have little to no effect on humans. Examples may include sources of free silver ions, which are noted for their antimicrobial effects and few biological effects on humans. Metal ion antimicrobial activity may be created by a variety of methods that may include, for example, mixing a source of a metal ion with the polymeric layer, for example, sheet or coating material during manufacture, coating the surface by methods such as plasma deposition, loosely complexing the metal ion source by disrupting the surface of the polymeric layer, for example, coating or sheet to form affinity or binding sites by methods such as etching or coronal discharge, and depositing a metal onto the surface by means such as electroplating, photoreduction and precipitation. The coated surface may then slowly release free metal ions during use that may produce an antimicrobial effect. 
         [0049]    In some embodiments, the source of metal ions may be an ion exchange resin. Ion exchange resins are substances that carry ions in binding sites on the surfaces of the material. Ion exchange resins may be impregnated with particular ion species for which it has a given affinity. The ion exchange resin may be placed in an environment containing different ion species for which it has a generally higher affinity, causing the impregnated ions to leach into the environment, being replaced by the ion species originally present in the environment. 
         [0050]    In one embodiment, the polymeric layer, for example, sheet or sprayed coating may include an ion exchange resin containing a metal ion source, such as, for example, silver. Ion exchange resins containing metal ion sources may include, for example, Alphasan® (Milliken Chemical), which is a zirconium phosphate-based ceramic ion exchange resin containing silver. An ion exchange resin may be coated onto the polymeric layer, for example, sheet or sprayed coating or it may be incorporated into the material of the sheet or sprayed coating, as discussed above. 
         [0051]    In some embodiments, a layer of substantially non-permanent coating including an anti-microbial compound may be present on top of a layer of a substantially permanent coating including an anti-microbial compound. 
         [0052]    The substantially permanent anti-microbial coating may be, for example, substantially flexible so that the coating substantially covers the working surfaces of the loading bearing structure during use even if the structure flexes. If the anti-microbial compound is not capable of forming a substantially flexible coating by itself, then a binding agent capable of forming a substantially flexible coating may be used to aid in the flexibility of the resulting coating. 
         [0053]    Other objects, features and advantages of the invention should be apparent from the following description of a preferred embodiment thereof as illustrated in the accompanying drawing. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0054]      FIG. 1  is a perspective view of a top side of a core of a dunnage platform that is in accordance with the invention; 
           [0055]      FIG. 2  is a perspective view of a bottom side of the core of  FIG. 1 ; 
           [0056]      FIG. 3  shows a line drawing of a loaded cargo carrier dunnage platform with a half enclosure positioned on the cargo carrier dunnage platform, according to an embodiment of the invention; 
           [0057]      FIG. 3A  shows a line drawing of the cargo carrier dunnage platform with phase change material containers positioned in pockets; 
           [0058]      FIG. 4  are shows an embodiment of a dunnage platform of the present invention; 
           [0059]      FIG. 4A  shows a line drawing of the empty cargo carrier dunnage platform with a half enclosure positioned on the cargo carrier dunnage platform, according to an embodiment of the invention; 
           [0060]      FIG. 4B  shows a line drawing of a closed cargo carrier dunnage platform with a both-half enclosures positioned on the cargo carrier dunnage platform, according to an embodiment of the invention 
           [0061]      FIG. 5  shows an embodiment of a container of the present invention during assembly; 
           [0062]      FIG. 6  shows an embodiment of a container of the present invention during assembly; 
           [0063]      FIG. 7  shows an embodiment of a container of the present invention during assembly; 
           [0064]      FIG. 8  shows an embodiment of a container of the present invention during assembly, depicting the interconnecting features; 
           [0065]      FIG. 8A  shows an embodiment of a container of the present invention depicting the interconnecting features during assembly; 
           [0066]      FIG. 8B  shows an embodiment of a container of the present invention depicting the interconnecting features during assembly; 
           [0067]      FIG. 8C  shows an embodiment of a container of the present invention depicting the interconnecting features during assembly; 
           [0068]      FIG. 8D  shows an embodiment of a container of the present invention depicting the interconnecting features during assembly; 
           [0069]      FIG. 8E  shows an embodiment of a container of the present invention depicting the interconnecting features during assembly; 
           [0070]      FIG. 9  shows a line drawing of the empty cargo carrier dunnage platform with a half enclosure positioned on the cargo carrier dunnage platform, according to another embodiment of the invention; 
           [0071]      FIG. 10  shows an L-shaped half of an embodiment of the container having features for locating cargo or partitions; 
           [0072]      FIG. 10A  show a full view of the inside bottom of an embodiment of the container of the present invention having features for locating cargo or partitions; 
           [0073]      FIG. 11  shows fully assembled container of an embodiment of the present invention; and 
           [0074]      FIG. 11A  shows an L-shaped half of an embodiment of the container having features for locating cargo. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0075]    The detailed description set forth below is intended as a description of the presently exemplified systems, devices and methods provided in accordance with aspects of the present invention and are not intended to represent the only forms in which the present invention may be prepared or utilized. It is to be understood, rather, that the same or equivalent functions and components may be accomplished by different embodiments that are also intended to be encompassed within the spirit and scope of the invention. 
         [0076]    Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this invention belongs. Although any methods, devices and materials similar or equivalent to those described herein can be used in the practice or testing of the invention, the exemplary methods, devices and materials are now described. 
         [0077]    All publications mentioned herein are incorporated herein by reference for the purpose of describing and disclosing, for example, the designs and methodologies that are described in the publications which might be used in connection with the presently described invention. The publications listed or discussed above, below and throughout the text are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the inventors are not entitled to antedate such disclosure by virtue of prior invention. 
         [0078]    The loading bearing structure of the present invention, which may be a dunnage platform or container, may have anti-microbial properties. Antimicrobial means an agent that is active against one or more organisms including bacteria, viruses, fungi, protists, helminths and insect larvae. Foreign hosts mean a microbe, pathogen or organisms that can be transported on a surface of a load bearing structure. 
         [0079]    In one exemplary embodiment, an antimicrobial agent capable of eliminating, preventing, retarding or minimizing the growth of microbes may be present on the exposed surfaces, for example, top side  16 , the edge  12  and/or the bottom side  18  of loading bearing structure  10 , as shown in  FIG. 1 . In  FIG. 1 , an expanded polymer core  10   a,  for example, a polystyrene core, is in the general shape of a rectangular slab with an edge  12   a  ( FIG. 1 ) that has a width  14   a  which may be, for example, approximately one and three-fourths to about two inches. The core  10   a  may have a smooth topside  16   a  covered with a polymeric layer, for example, a high impact polymeric sheet  67 , such as a high impact polystyrene sheet, that may be in the order of approximately four feet long and forty inches wide. A bottom side  18   a,  as shown in  FIG. 2  of the core  10   a  may include legs  20 - 28 . These legs may extend, for example, approximately four to six inches therefrom. 
         [0080]    The load bearing structure  10  also has a width  14 , which is the combined total width of the core  10   a  and sheet  67 , mentioned above. 
         [0081]    The load bearing structure may also include a plurality of wear resistant members that may be affixed to the second side of at least some of the legs  20 - 28  of all of the embodiments of loading bearing structures described herein. Details of the wear resistant members may be found in U.S. Pat. Nos. 7,908,979, and 5,868,080, the contents of all of which are hereby incorporated by reference. 
         [0082]    These wear resistant members may be similar to bridges that extend between adjacent legs. In some embodiments, only one of these members may be present. In other embodiments, two of these may be arranged in the shape of a cross. In further embodiments, one of each may be attached to each pair of adjacent legs around the peripheral of the load bearing structure. In still other embodiments, they may be attached to every pair of legs of the load bearing structure. 
         [0083]    In one embodiment, at least one antimicrobial agent may be added to the material used for making the polymeric layer, for example, sheet  67 . The antimicrobial agent may be in powder form or in liquid form. In another embodiment, at least one antimicrobial agent may be coated onto the exposed surface  16  of the polymeric layer, for example, sheet  67 . The antimicrobial agent may be in powder form or in liquid form. 
         [0084]    For light weight load bearing structures, the core  10   a  is generally made of foam, for example, a closed cell foam core  10   a  such as an expanded polystyrene core  10   a  with a region proximal to its surface that is combined with a polymeric layer, for example, high impact polymeric sheet  67 , for example, a polystyrene sheet, by heat and/or pressure. In some embodiments, a polyurethane core  10   a  may be used and may be covered with a polymeric layer, for example, a sprayed coating  67  of, for example, polyurea. 
         [0085]    The foam core  10   a  may be made from already manufactured bulk form, such as expanded polystyrene foam which may be cut to the desired shape and size; or may be foamed in place in a mold of the size and shape desired, such as a polyurethane foam. The foam density may also be varied, depending on the degree of expansion of the beads used to make the foam. The foam density may also decide the suitable load or cargo to be loaded. 
         [0086]    The foam core in general by itself, unless it is of higher density, for example, the beads are not highly expanded, may not have sufficient structural strength to be useable as a load bearing platform. A dunnage platform with sufficient strength may be formed by combining the core  10   a  with a high impact polymeric sheet  67 , for example, a polystyrene Sheet. In one embodiment, the sheet  67  may include an antimicrobial agent, which may be added to the material used for making the sheet  67 . The antimicrobial agent may be in powder form or in liquid form. In another embodiment, at least one antimicrobial agent may be coated onto the exposed surface  16  of the sheet  67 . The antimicrobial agent may be in powder form or in liquid form. When the agent is coated, the coating may take place before the sheet  67  is combined with the core  10   a  or after the load bearing structure  10  is made. 
         [0087]    The combination may be effected by heat and/or pressure. In one specific example of a load bearing structure, a combination process may cause portions of an expanded polystyrene core  10   a  proximal to the bottom side  18   a  to be combined with the high impact polystyrene sheet  67  to form a strengthened polystyrene by heat and pressure. Additionally, a portion of the expanded polystyrene that is proximal to the edge  12   a  and in a proximal relationship to the bottom side  18   a  may be combined with the high impact polystyrene by heat and pressure to form the strengthened polystyrene, if desired. Details of this combination process may be found in U.S. Pat. No. 6,786,992, the content of which is incorporated herein by reference in its entirety. 
         [0088]    Another specific example of a load bearing structure  10  may be as disclosed in U.S. Pat. No. 7,908,979, WO04041516 and U.S. Pat. No. 7,413,698, the contents of all of which are incorporated herein by reference in their entirety. 
         [0089]    Referring to  FIG. 2 , the edge  12   a  is proximal to spaces  42 ,  44 ,  46 ,  48  on the bottom side  18   a.  The marginal spaces  42 ,  44 ,  46 ,  48  separate the legs  26 - 28 , the legs  20 ,  23 ,  26 , the legs  20 - 22  and the legs  22 ,  25 ,  28 , respectively, from the edge  12   a.    
         [0090]    As noted above, the structure  10  may be also made by injecting a polymer into a mold to form the core  10   a  and after removing the core  10   a  from the mold spraying a polymer coating  67  on the polymer core  10   a.  For example, liquid polyurethane may be injected into a mold to form a polyurethane core  10   a  containing grooves, protrusions and/or pockets that may be used to locate phase change materials, which after curing is removed from the mold and sprayed with polyurea to form one or more of the load bearing structures  10 . In one embodiment, the polymer coating may include an antimicrobial agent therein. In another embodiment, an antimicrobial coating may be applied to at least one of the exposed surfaces of the structure  10  after forming the structure. 
         [0091]    In another exemplary embodiment, an antimicrobial coating capable of eliminating, preventing, retarding or minimizing the growth of microbes may be present in the materials making up the polymeric layer, for example, sheets or sprayed coatings or coated on the exposed surface or surfaces of any of the walls, top and base components of a container, as shown in  FIG. 5-FIG .  7 , and  FIGS. 8 ,  8 A- FIG. 8E , which may be assembled from the load bearing structure, as shown in  FIG. 1 . 
         [0092]    The containers may have a base in the structure of, for example,  FIG. 4 , which may also be made either by combining the core  10   a  with a polymeric sheet  67 , as noted above for  FIG. 1 , or by injecting a polymer into a mold to form the core  10   a  and after removing the core from the mold, spraying a polymer coating  67  on the polymer core  10   a.  For example, liquid polyurethane may be injected into a mold to form a polyurethane core containing grooves, protrusions and/or pockets which after curing may be removed from the mold and sprayed with polyurea to form one or more of the load bearing structure  10 . 
         [0093]    In  FIG. 3 , a line drawing of a loaded cargo carrier dunnage platform with a half enclosure  380  positioned on the cargo carrier dunnage platform loaded with cargo  490 , according to an embodiment of the invention. Referring again to  FIG. 4 , the cargo carrier dunnage platform  10  may be useful as a base of the container of  FIG. 3 , with a top surface  115  and edges  110  is shown. In this embodiment, the dunnage platform  10   a  shown has six (6) pockets  125  and two (2) grooves or recesses  130  penetrating the top surface  115 , each of which may extend into the core  10   a  (not shown) of the dunnage platform  10 . In an embodiment of the invention, the pockets  125  may be used to locate phase change materials. In an embodiment of the invention, the grooves or recesses  130  are used to locate one or more enclosures.  FIG. 4(A)  shows the container of the embodiment of  FIG. 3 , devoid of cargo. 
         [0094]      FIG. 3A  shows the cargo carrier dunnage platform with phase change material containers or pouches  125   a  positioned in pockets  125  and a half enclosure positioned on the cargo carrier dunnage platform, according to an embodiment of the invention. These containers or pouches are shown here in substantially rectangular form, but they may be in other forms. 
         [0095]    In another embodiment, as shown in  FIG. 9 , the base may also be such as shown in  FIG. 1 , but again with groove  130 . 
         [0096]    In one exemplary embodiment, a container  100  ( FIG. 5 ) or  300  ( FIG. 6 ) may be a knock-down or collapsible shipping container made up of a plurality of surfaces including a base  106  or  306 , four walls  101  ( 103 ) or  301  ( 303 ) and a top panel  404  (as shown in  FIG. 7 ), each being made from a light weight core laminated with a thermoplastic. In one embodiment of the invention structural metal mesh can be inserted into the core  101   a  (not shown) to resist piercing of any of the surfaces. In another embodiment of the invention, the walls are held together with clasps  450 , as shown in  FIG. 7 . The shipping and/or storage container  400  is modular, lightweight, and may be thermally insulating, and/or tamper proof, and provides a sanitary surface coating and thermal capacity for transportation of foodstuffs and other valuable products. Upon delivery and unloading, the walls and top of the container can be disassembled and stacked on the dunnage base to reduce the volume of the container for storage or further shipment. The detail of this container is as described in U.S. Pat. No. 7,963,397, the content of which is hereby incorporated by reference in its entirety. 
         [0097]    In another exemplary embodiment of the invention, a knock down or collapsible container for storage and/or shipping having a base, four walls extending therefrom and a top panel to form an enclosure therein, each of which having an inside surface, an outside surface, a width joining the inside and outside surfaces, and four inside edges and four outside edges. The container when collapsed or knock-down, has a foot print not larger than the foot print of the largest individual component, as shown in  FIG. 8 ,  FIG. 8A-FIG .  8 E. In an embodiment of the invention, each of the base, four walls and top includes a continuous feature extending substantially along a surface no more than approximately 80 percent, of any of the four inside edges of the walls, base and top of each of the components of the container, the features on adjacent members are of opposite interlocking characteristics, as shown in  FIG. 8 ,  FIG. 8A-FIG .  8 E. That is, if an edge has a groove, the groove is less than 80 percent of the length of the edge. 
         [0098]    In an alternative embodiment of the invention, each of the base, four walls and top includes a continuous feature extending substantially along a surface no more than approximately 90 percent of any of the four inside edges of the walls, base and top of each of the components of the container, the features on adjacent members are of opposite interlocking characteristics. That is, if an edge has a groove, the groove is less than 90 percent of the length of the edge. 
         [0099]    Interlocking features characteristics may also be defined as a depression in a wall of a container corresponding to a protrusion in the cargo such that the container ‘mates’ with the cargo without requiring a fastener. Interlocking characteristics may include respective depression and protrusion features on adjacent connecting components. For example, when the features along one side have a receiving characteristic, the features on the adjacent member are of a protruding characteristic so that the interlocking features mate to form a container without any aid from additional clips or fasteners. The phrase ‘without requiring a fastener’ means that the interlocking features are interlocked without the aid of any component that is not the base, the four walls or the top. Additional securing devices may be employed to insure further integrity of the container, if needed, and such additional securing devices may include straps and/or shrink wrap packaging. In one embodiment, each of the walls, top and base of the container may be made of a light weight core substantially covered with a polymeric layer, for example, high impact sheet, having antimicrobial properties or having at least one antimicrobial agents incorporated therein or thereon, on at least one of its surfaces to form a load bearing structure having a width as noted above. In another embodiment, a structural metal mesh may be inserted into the core to resist piercing of the surface, and each of the walls, top and base of the container may be made of a light weight core substantially covered with a polymeric layer, for example, high impact sheet, having antimicrobial properties or having at least one antimicrobial agents incorporated therein or thereon, on at least one of its surfaces to form a load bearing structure having a width as noted above. In a further embodiment of the invention, one or more of the walls, top and base portions may be made by injecting a polymer into a mold to form the core and after removing the core from the mold spraying a polymer coating on the polymer core. In one example, liquid polyurethane may be injected into a mold to form a polyurethane core containing grooves, protrusions and/or pockets which after curing is removed from the mold and sprayed with polyurea having antimicrobial properties or having at least one antimicrobial agents incorporated therein to form one or more of the load bearing structures. In another example, a coating having antimicrobial properties or having at least one antimicrobial agents incorporated therein may be coated onto the polyurea coating. 
         [0100]      FIG. 8  illustrates a perspective view of an assembled container  800  which may generally include a base  812 , side pieces  801 ,  802 ,  803  and  804 , and a top  816 . In general, the container  800  may be assembled into the form illustrated in  FIG. 8  without the use of adhesives, fasteners and/or other assembly aids and may substantially assemble in a predetermined fashion and retain the illustrated form. In one embodiment, as shown in  FIG. 8A , the base  812  may generally be rectangular and may include a plurality of channels or grooves  831 ,  832 ,  833  and  834 , each adjacent to an edge of the base  812 . The grooves  831 ,  832 ,  833  and  834  may each terminate at a corner which is substantially open to the edge, as shown with corners  812   a, b, c  and  d,  such that the grooves are open at least one end to insert a side piece. The corners  812   a, b, c  and  d  may also include a closed edge which may thus act as a stop such that, for example, a side piece(s) may abut against the closed edge of the corner and be substantially retained and prevented from advancing beyond the corner. As illustrated in  FIG. 8B , a side piece, such as side piece  801 , may include a corresponding ridge  841 , which may slide into and be retained in a corresponding groove, such as groove  831  as illustrated. The side pieces, such as illustrated with side piece  801 , may further include a ridge  841  a opposite ridge  841  which may correspond and be retained in a corresponding groove of the top  816 . 
         [0101]    In general, the side pieces  801 ,  802 ,  803  and  804  may include edges orthogonal to ridges which correspond to the grooves of the top  816  and base  812 , as illustrated in the top view of the container  800  in  FIG. 8C . In general, the orthogonal edges may mate to each other with interlocking connections, as illustrated with connections  853 ,  854  and  855 . In general, to assemble the container  800 , for example, the side piece  804  may be inserted into the groove  834 , followed by side piece  803  in groove  833 , side piece  802  in groove  832  and then side piece  801  in groove  831 . Side pieces  801  and  802  may include a non-interlocking junction, as illustrated with abutting edges  851  and  852 , such that side piece  801  may be inserted without interference from a protruding piece. The top  816  as illustrated in  FIG. 8D , which may include grooves  833   a,    833   b,    833   c  and  833   d,  which may correspond to ridges  842   a,    842   b,    842   c  and  842   d  of the side pieces, respectively, may then be placed such that the corresponding ridges fit into the grooves of the top  816 , closing the container  800 . The top  816  may also, for example, be placed before all of the side pieces are placed, such as illustrated in  FIG. 8E . The side pieces, such as side piece  801  as illustrated in  FIG. 8E , may also include handling features, such as the handle depressions  801   d,  such that the side pieces may be manipulated with greater ease. 
         [0102]    These embodiments of the container is described in detail in co-pending U.S. Patent Application, entitled “Cargo Container for Storing and Transporting Cargo”, to be concurrently filed, the content of which is hereby incorporated by reference in its entirety. 
         [0103]    In a further exemplary embodiment, the container includes two identical substantially L-shaped cross-section halves,  380 , each having at least two walls and a base or top component, each of the components having corresponding or complementary interlocking features to be mated together to form a container having an enclosure therein, as shown in  FIG. 4A . In other embodiments, the base may not have pockets. Each of the halves having an inner surface and an outer surface joined by a width. The footprint of the knock-down or collapsed container is not larger than the substantially L-shaped cross-section halves. In one embodiment, each half is made of an inner light weight core covered by at least one layer of strengthened coating. In another embodiment, a structural metal mesh may be inserted into the core to resist piercing of the surface. In a further embodiment, one or more of the substantially L-shaped cross-section halves may be made by injecting a polymer into a mold to form the core and after removing the core from the mold, spraying a polymer coating on the polymer core. For example, liquid polyurethane may be injected into a mold to form a polyurethane core containing grooves and pockets which after curing may be removed from the mold and sprayed with polyurea to form one or more of the load bearing structure and the half enclosures. In one aspect, the container may have thermal insulating property for minimizing exposure of cargo to cold temperatures. In another aspect, the container may have thermal insulating property for minimizing exposure of cargo to high temperatures. In a further aspect, the container may have a combination of any of the properties described in the previous aspects. According to one embodiment, the container may include an enclosure having one undivided internal compartment. According to another embodiment, the container may include an enclosure having more than one internal compartments. These embodiments are also disclosed in U.S. Patent Application entitled “Cargo Container for Storing and Transporting Cargo”, and U.S. Patent Application entitled “Climate control Cargo Container for Storing, Transporting and Preserving Cargo”, to be concurrently filed, the contents of which are incorporated herein by reference in their entirety. 
         [0104]    As noted above, the containers include those as described in  FIGS. 5 ,  6  and  7 , (and also disclosed in U.S. Pat. No. 7,963,397, the contents of which is incorporated herein in its entirely,) at least one of the exposed surfaces thereof may have antimicrobial properties and pockets may be added for containing phase change materials. 
         [0105]    According to one embodiment, the container may include an enclosure having one undivided internal compartment, as shown in  FIG. 3 ,  FIG. 8C  or  FIG. 10 . According to another embodiment, the container may include an enclosure having more than one internal compartments, not specifically shown. In one aspect, the interior may have dividers molded into the side of the component structures (not specifically shown). In another aspect, the dividers may be added to the container to form separate compartments. Features  612  or  622 , as shown in  FIG. 10 ,  FIG. 10A  and  FIG. 11A , may be present or molded into the components of the container to allow for placement of dividers to adjust the size of the compartments. 
         [0106]      FIG. 10 ,  FIG. 10A  and  FIG. 11A  show embodiments of a substantially L-shaped cross-section half of a container  600 , having channel or groove,  130 , molded or formed on the various sides. Slots  612  or  622 , are molded or formed on the interior of all side, base or top components,  610  or  620  of  FIG. 10 ,  10   a  or  11   a , for attaching dividers (not shown) to create various compartments inside the enclosure, or for attaching shaped features  700  for resting cargo, as shown in  FIG. 11A . In one embodiment, the slots  612  or  622 , may be formed or molded in fixed distance apart, as shown in  FIG. 10 ,  FIG. 10A  and  FIG. 11A  so that same size or multiples of one size compartments may be formed. In another embodiment, they may be formed or molded in varied distance apart (not specifically shown), so that different size compartments may be formed which may or may not be multiples of one size. In one aspect, the slots are formed at corresponding positions on the inside surfaces of the side, top or bottom components to form compartments that are either substantially parallel to the horizontal or vertical. In another aspect, the slots are formed at an angle with respect to the horizontal or vertical. 
         [0107]    According to one embodiment, features  700  may be formed or molded into the components of the container for placement of cargo or placement of other components for more secure location of cargo. 
         [0108]      FIG. 11  shows a closed container  600  by mating two substantially L-shaped cross-section halves, such as that shown in  FIG. 10  or  FIG. 11A . 
         [0109]    The containers may be made of the size and shape to accommodate the cargo, or the cargo may be contained in its own packaging and then inserted into the container  380  or  600 . 
         [0110]    As noted above, the polymeric layer, for example, sheets or sprayed coating or the coatings thereon the polymeric layer, for example, sheets or sprayed coatings may include chemical anti-microbial materials or compounds that are capable of being substantially permanently bonded, at least for a period such as the useful life of the loading bearing structure or maintain their anti-microbial effects when coated with the aid of processing aids or coating agents, onto the exposed surfaces of the polymeric layer, for example, sheet or coating  67 . In one example, the chemicals may be deposited on the surface of the polymeric layer, for example, sheet or coating  67  or incorporated into the material of the polymeric layer, for example, sheet or coating  67 . Antimicrobial activity may be built into the surface  16  itself by, for example, covalently bonding antimicrobial agents to the surface of the polymeric layer, for example, sheet or coating  67 , or if incorporated into the bulk of the material for making the polymeric layer, for example, sheet or sprayed coating, may migrate to the surface. These covalently bonded materials may act to minimize microbial growth on the surface, either disposable or reusable. In addition, any microbial organisms that may chance to be attached to the material may be killed by interaction with the coating. For example, quaternary ammonium cations, such as N-alkyl-pyridiniums, may be used as antimicrobial moieties in covalently attached polymeric surface coatings. In one case, poly(4-vinyl-N-hexylpyridinium) (N-alkylated-PVP) was previously noted to have an optimum alkyl side chain length for antimicrobial activity. Polyethylenimine (PEI) was also previously used as a bacteriocidal coating when both N-alkylated on its primary amino group and subsequently N-methylated on its secondary and tertiary amino groups to raise the overall number of cationic quaternary amino groups. Any such covalently bonded quaternary ammonium cation polymeric coatings may be used to give an antimicrobial property to the surface or surfaces of the loading bearing structures. Further examples of quaternary ammonium compounds include, but are not limited to, benzalkonium chloride, benzethonium chloride, methylbenzethonium chloride, cetalkonium chloride, cetylpyridinium chloride, cetrimonium, cetrimide, dofanium chloride, tetraethylammonium bromide, didecyldimethylammonium chloride and domiphen bromide. 
         [0111]    For bulk incorporation of the antimicrobial agent or agents into the material used in making the polymeric layer, for example, sheet or sprayed coating, the agent or agents maybe dispersed directly into the material, or with the aid of an appropriate carrier, for example, a binding agent, a solvent, or a suitable polymer mixing aid. These carriers maybe chosen so that they are mixable with the material for making the polymeric layer, for example, sheets or sprayed coatings and compatible with the antimicrobial agent or agents used. Effective binding agents are those that do not interfere with the antimicrobial activities of the antimicrobial agent. 
         [0112]    Depending on the materials used or the type of antimicrobial agents, appropriate carriers may be more or less hydrophobic, or it may even be both hydrophilic and hydrophobic. For surface coatings, the same properties may also be true of the coating aids. For example, useful carriers may include polymers of monoolefins and diolefins, e.g. polypropylene, polyisobutylene, polybut-1-ene, poly-4-methylpent-1-ene, polyvinylcyclohexane, polyisoprene or polybutadiene, and polymers of cycloolefins, e.g. of cyclopentene or norbornene, polyethylene (which may optionally be crosslinked), e.g. high density polyethylene (HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), (VLDPE) and (ULDPE); copolymers of monoolefins and diolefins with one another or with other vinyl monomers, e.g. ethylene/propylene copolymers, linear low density polyethylene (LLDPE) and blends thereof with low density polyethylene (LDPE), propylene/but-1-ene copolymers, propylene/isobutylene copolymers, ethylene/but-1-ene copolymers, ethylene/hexene copolymers, ethylene/methylpentene copolymers, ethylene/heptene copolymers, ethylene/octene copolymers, ethylene/vinylcyclohexane copolymers, ethylene/cycloolefin copolymers (e.g. ethylene/norbornene, such as COC), ethylene/1-olefin copolymers, the 1-olefin being produced in situ; propylene/butadiene copolymers, isobutylene/isoprene copolymers, ethylene/vinylcyclohexene copolymers, ethylene/alkyl acrylate copolymers, ethylene/alkyl methacrylate copolymers, ethylene/vinyl acetate copolymers or ethylene/acrylic acid copolymers and salts thereof (ionomers) and terpolymers of ethylene with propylene and a diene, such as, for example, hexadiene, dicyclopentadiene or ethylidenenorbornene; homopolymers and copolymers that may have any desired three-dimensional structure (stereo structure), such as, for example, syndiotactic, isotactic, hemiisotactic or atactic Stereo block polymers are also possible; polystyrene, poly(p-methylstyrene), poly(alpha-methylstyrene); aromatic homopolymers and copolymers derived from vinylaromatic monomers, including styrene, alpha-methylstyrene, all isomers of vinyltoluene, in particular p-vinyltoluene, all isomers of ethylstyrene, propylstyrene, vinylbiphenyl, vinylnaphthalene and vinylanthracene and blends thereof, homopolymers and copolymers may have any desired three-dimensional structure, including syndiotactic, isotactic, hemiisotactic or atactic, stereo block polymers; copolymers, including the abovementioned vinylaromatic monomers and co-monomers selected from ethylene, propylene, dienes, nitriles, acids, maleic anhydrides, maleimides, vinyl acetates and vinyl chlorides or acryloyl derivatives and mixtures thereof, for example styrene/butadiene, styrene/acrylonitrile, styrene/ethylene (interpolymers), styrene/alkylmethacrylate, styrene/butadiene/alkyl acrylate, styrene/butadiene/alkyl methacrylate, styrene/maleic anhydride, styrene/acrylonitrile/methyl acrylate; blends having a high impact strength and comprising styrene copolymers and other polymers, e.g. polyacrylates, diene polymers or ethylene/propylene/diene terpolymers; and block copolymers of styrene, such as, for example, styrene/butadiene/styrene, styrene/isoprene/styrene, styrene/ethylene/butylene/styrene or styrene/ethylene/propylene/styrene. Hydrogen-saturated aromatic polymers derived by hydrogen saturation of said polymers, in particular including polycyclohexylethylene (PCHE) prepared by the hydrogenation of atactic polystyrene (frequently designated as polyvinylcyclohexane (PVCH)); polymers derived from alpha, beta-unsaturated acids and derivatives thereof, such as, for example, polyacrylates, polymethacrylates, polymethyl methacrylates, polyacrylamides and polyacrylonitriles, made impact-resistant with butyl acrylate, copolymers of said monomers with one another and with other unsaturated monomers, such as, for example, acrylonitrile/butadiene copolymers, acrylonitrile/alkyl acrylate copolymers, acrylonitrile/alkoxyalkyl acrylates or acrylonitrile/vinyl halide copolymers or acrylonitrile/alkyl methacrylate/butadiene terpolymers; polymers derived from unsaturated alcohols and amines or from acyl derivatives or acetals thereof, for example polyvinyl alcohol, polyvinyl acetate, polyvinyl stearate, polyvinyl benzoate, polyvinyl maleate, polyvinyl butyral, polyallyl phthalate or polyallylmelamine; and copolymers thereof with olefins; homopolymers and copolymers of cyclic ethers, such as, for example, polyalkylene glycols polyethylene oxide, polypropylene oxide or copolymers thereof with bisglycidyl ethers; polyacetals, such as, for example, polyoxymethylene and those polyoxymethylenes which contain ethylene oxide as a co-monomer, polyacetals modified with thermoplastic polyurethanes, acrylates or MBS; polyamides and co-polyamides derived from diamines and dicarboxylic acids and/or from aminocarboxylic acids or the corresponding lactams, for example polyamide 4, polyamide 6, polyamide 6/6, 6/10, 6/9, 6/12, 4/6, 12/12, polyamide 11, polyamide 12, aromatic polyamides starting from m-xylenediamine and adipic acid; polyamides prepared from hexamethylenediamine and isophthalic and terephthalic acid as starting materials and with or without an elastomer as a modifier, for example poly-2,4,4-trimethylhexamethyleneterephthal-amide or poly-m-phenyleneisophthalamide; and also block copolymers of said polyamides with polyolefins, olefin copolymers, ionomers or chemically bonded or grafted elastomers; polyamides with polyethers, for example with polyethylene glycol, polypropylene glycol or polytetramethylene glycol; and also polyamides or co-polyamides modified with EPDM or ABS; polyamides condensed during the preparation (RIM polyamide systems); polyesters derived from dicarboxylic acids and diols and/or from hydroxycarboxylic acids or the corresponding lactones, for example polyethylene terephthalate, polybutylene terephthalate, poly-1,4-dimethylolcyclohexane terephthalate, polyalkylene naphthalate (PAN) and polyhydroxybenzoate, and also block copolyetheresters derived from hydroxyl-terminated polyethers; polycarbonates and polyestercarbonates, polyketones, polysulfones, polyethersulfones and polyetherketones; crosslinked polymers derived from aldehydes on the one hand and phenols, ureas and melamines on the other hand, such as, for example, phenol/formaldehyde resins, urea/formaldehyde resins and melamine/formaldehyde resins; unsaturated polyester resins derived from co-polyesters of saturated and unsaturated dicarboxylic acids, polyhydric alcohols and vinyl components as cross linking agents, and also halogen-containing modifiers thereof having low flammability; crosslinked acrylic resins derived from substituted acrylates, e.g. epoxyacrylates, urethaneacrylates or polyesteracrylates; starch; polymers and co-copolymers of materials such as polylactic acids and its copolymers, cellulose, polyhydroxy alcanoates (PHA), polycaprolactone (PCL), polybutylene succinate (PBS)) polymers and copolymers of N-vinylpyrrolidone such as polyvinylpyrrolidone, poly(vinylpyrrolidone-co-vinyl acetate), and crosslinked polyvinylpyrrolidone, Ethylene Vinyl Alcohol (EvOH). 
         [0113]    More for example, examples of thermoplastic polymers that may be suitable as carriers may include the following: Polypropylene, High Density Polyethylene, Polyolefin combined with MS0825 Nanoreinforced® POSS® Polypropylene, thermoplastic elastomers, thermoplastic vulcinates, Polyvinylchloride, Polylactic acid, Polyester, unsaturated polyesters, acrylnitrilebutadiene styrene, Polyoxamethalyne, Cellulosics, Polyamides, Polyamideimides, ionomer, Polycarbonate, Polybutylene terephthylate, Polyester elastomers, Linear low density polyethelene, thermoplastic polyurethane, cyclic olefin copolymer, bi-axially oriented polypropylene, ethylene copolymers, various biodegradable polymers such as Cereplast-Polylactic Acid, Purac-Lactide® PLA, Nec Corp PLA, Mitsubishi Chemical Corp GS PLA resins, Natureworks LLC PLA, Cereplast-Biopropylene®, Spartech®-PLA Rejuven8 Plus, resins made from starch, cellulose, polyhydroxy alcanoates (PHA), polycaprolactone (PCL), polybutylene succinate (PBS), or combinations thereof, such as Ecoflex F BX 7011 and Ecovio L Resins from BASF, Germany, Polyvinylchloride, and recycled and reclaimed Polyester such as recycled soda bottles, Ecoflex F BX 7011 from BASF, Germany, and Nodax®—biodegradable polyester made by P&amp;G of Cincinnati, Ohio. 
         [0114]    The carriers may generally be present in a low percentage of the total amount of the material used for making polymeric layer, for example, sheets or sprayed coatings so that the effect, if any, on the properties of the polymeric layer, for example, sheets or sprayed coating may be minimized. In one embodiment, when the anti-microbial agent is incorporated into the material used either for making the polymeric layer, for example, sheet or sprayed coating mentioned above, the antimicrobial agent maybe master batch in the material or an appropriate carrier to form a concentrate at a higher concentration prior to adding to the material for making the sheet or sprayed coating in desired proportions. In another embodiment, the antimicrobial agent may be added directly to the material or making the polymeric layer, for example, sheet or sprayed coating without the intermediate step. 
         [0115]    For master batch operations, the carrier may be provided in an amount of, for example, from about 10% to about 50% by weight of the polymeric layer, for example, sheet, or sprayed coating  67 ; more for example, from about 10% to about 25% by weight, and even more for example, from about 10% to about 15% by weight; so that when the master batch is diluted into the material for making the polymeric layer, for example, sheet or sprayed coating  67 , the amount is minuscule. 
         [0116]    These carriers may also be useful for coating aids mentioned above and may be in the same amount as noted above. Master batching may also be employed. 
         [0117]    Antimicrobial coatings may be covalently attached to the surface by a variety of methods and may include, for example, creating suitable reaction sites, such as free hydroxyl or amino groups, by coronal discharge, surface etching, hydrolyzation or other methods that disrupt the smooth surface  16  of the structure  10  to create sites of suitable reactivity. The antimicrobial coatings may then be synthesized by reacting the various precursors with the prepared surface of the polymeric layer, for example, sheet or coating  67  to build the proper coating. In other cases, silanes may be used as coupling agents to complex antimicrobial moieties to the surface of the polymeric layer, for example, sheet or coating  67 . Silanes or other strong affinity coupling agents may be used in particular to bond coatings to polymer surfaces that may resist other forms of attachment. Effective coupling agents are those that do not interfere with the antimicrobial properties of the antimicrobial agent or agents. 
         [0118]    In other embodiments, to increase the coating efficiency, the exposed surfaces to be coated may be roughened or pitted. 
         [0119]    For bulk incorporation, antimicrobial agent or agents may migrate to the surface and be covalently bonded to the surface. 
         [0120]    In other embodiments, the coatings may include chemical antimicrobial materials or compounds that may be deposited onto exposed surface  16  in a non-permanent manner such that they may dissolve, leach or otherwise deliver antimicrobial effects during use, for example, in a moist environment. For bulk incorporation, antimicrobial agent or agents may migrate to the surface and be non-permanently bonded to the surface. 
         [0121]    Chemical antimicrobial materials or compounds may include a variety of substances including, but not limited to antibiotics, antimycotics, general antimicrobial agents, metal ion generating materials, or any other materials capable of generating an antimicrobial effect. The anti-microbial compound may include, but are not limited to, antibiotics, quaternary ammonium cations, a source of metal ions, triclosan, chlorhexidine, and/or any other appropriate compound or mixtures thereof. The anti-microbial compound may also include materials or substances which may release or generate reactive oxygen species. For example, titanium dioxide and/or zinc coatings may, when for example exposed to a source of light/UV radiation, air and moisture, photocatalyze the formation of reactive oxygen species, such as, for example, superoxide (O 2   − ) and hydroxyl radicals (OH). Reactive oxygen species may in general, inter alia, have an antimicrobial effect. 
         [0122]    Antimicrobial agents may be employed to retard or kill microbes on the surface Antimicrobial agents may include, but are not limited to, antibiotics such as β-lactams (e.g. penicillin), aminoglycosides (e.g. streptomycin) and tetracyclines (e.g. doxycycline), antimycotics such as polyene drugs (e.g. amphotericin B) and imidazole and triazole drugs (e.g. fluconazole), ternary complex of Cu(pcpa)2(aben)2 (pcpa=p-chlorophenoxyacetic acid anion, aben=2-amino benzothiazole), Methylenebis(phenyl-1,5-benzothiazepine)s, carbon nanotubes, such as single-walled nanotubes, and Methylenebis(benzofuryl-1,5-benzothiazepine)s, and general antimicrobial agents such as quaternary ammonium cations (e.g. benzalkonium chloride) and compounds such as triclosan. Polymeric antimicrobial compounds, which are based on positively charged amino acid residues and hydrophobic moieties, such as those disclosed in U.S. Pat. No. 7.504.381, the contents of which are incorporated herein by reference, may also be utilized. The composition may include a binding agent, an antimicrobial agent and/or other materials conducive to its retention on the surface or surfaces of the loading bearing structures and its use as a sterilizing agent. Suitable binding agents may include, but are not limited to, polymers such as polyethylene oxide (PEO), polylactic acid (PLA) and polyglycolic acid (PGA), polysaccharides such as carrageenan, chondroitin sulfate, ethylcellulose, hydroxypropylcellulose, carboxymethylcellulose, hydroxypropylmethylcellulose and polyvinylpyrrolidone. Effective binding agents are those that do not interfere with the antimicrobial activities of the antimicrobial agent. 
         [0123]    In still other embodiments, sources of anti-microbial agents may leach and/or release agents in a moist environment or upon contact with moisture. These sources may be incorporated into the substrate materials used for manufacturing the polymeric layer, for example, sheet or coating  67 , as discussed above, or included in the polymeric layer, for example, coatings or sheet  67  coated on the exposed surfaces  16  of the structure  10 . Incorporation of the sources is especially suited to polymeric substrates, as in the present invention. 
         [0124]    Water soluble or hydrophilic carriers such as hydroxypropylcellulose, polyvinylpyrrolidone or carrageenan may be employed to effect such action. In other embodiments, the antimicrobial agent may be retained in an insoluble carrier that may linger in the polymeric layer, for example, coating or sheet  67  and slowly release (time release) the agent. Insoluble high molecular weight carriers, such as PEO, or biodegradable carriers, such as PLA and PGA, may be employed to effect such action. 
         [0125]    The antimicrobial layer or coating may be present on the inside and/or outside of the container. 
         [0126]    The antimicrobial treatment may be active against one or more microbes or pathogens, not limited to bacteria, viruses, fungi, protists (for example, plasmodium), helminths and insect larvae. Bacteria may include gram negative and/or gram positive bacteria. The antimicrobial treatment may be active against  Escherichia coli, Salmonella, Shigella, Pseudomonas, Moraxella, Helicobacter, Strenotrophomonas, Bdellovibrio  and  Legionella . The antimicrobial treatment may be active against  Bacillus, Clostridium, Corynebacterium, Listeria  (L.),  Staphylococcus  and  Streptococcus . The antimicrobial treatment may be active against  L. dinitrificans, L. grayi, L. innocua, L. ivanovii, L. monocytogenes, L. murrayi, L. seeligeri  and  L. welshimeri.  The antimicrobial treatment may be active against one or more organisms including Hymenoptera (H.) Aculeata eggs and/or nests. As used here the term “active” means “toxic” and/or “killing” and/or to “inhibit propagation”. For example, toxic can describe an agent that interferes with RNA or DNA synthesis, causes RNA or DNA strand scission, blocks cell cycling, division, replication or is otherwise cytotoxic to the microbe, pathogen or organism. The term “active” with respect to inhibition may mean, for example, inhibition of a microbe or pathogen&#39;s DNA synthesis, which results in inhibition of DNA synthesis in an appropriate cultured cell line by between approximately 50% and approximately 95%. 
         [0127]    As noted above, an additional enclosure, such as bag like enclosure may be used to cover any of the load bearing structures described above. The present invention also discloses a system designed to facilitate the security checking process, including a light weight load bearing structure for loading perishable or non-perishable cargo, the load bearing structure having a top deck, a bottom deck and a width joining the top and the bottom, the bottom deck having a plurality of legs extending therefrom and the cargo is loaded onto the top deck of the load bearing structure; and a bag-like enclosure for covering the cargo and at least a portion of the width of the load bearing structure, with the bag-like enclosure having an opening with an elastic property about its circumference for stretching about the width of the load bearing structure. The load bearing structure and bag-like enclosure in this configuration are both transparent to magnetic imaging scanners used in security scanning to facilitate the security check of perishable cargo or non-perishable cargo, large or small, without the need for unloading and reloading of the cargo from the load bearing structure. 
         [0128]    The bag like enclosure may be made from a film, a woven sheet or a non-woven sheet having sufficient strength for stretching over and covering a cargo and light weight enough not to add unnecessary weight to the cargo. It may be closed on three sides and opened at one end, with the open end having some elastic property circumferentially about the opening. The cargo may be packed and the bag-like material stretched over the entire cargo with the open end stretched under the edge of base and tagged at the origin and the complete structure may be shrink-wrapped. The surfaces of the bag-like material may also have anti-microbial properties. Any of the antimicrobial embodiments described above may be suitable. More details are found in concurrently file U.S. Patent Application entitled “SYSTEM FOR FACILITATING SECURITY CHECK OF SHIPMENT OF CARGO”, the content of which is hereby incorporated by reference in its entirety. 
         [0129]    While the invention has been particularly shown and described with reference to exemplary embodiments, it should be understood by those skilled in the art that changes in form and detail may be made therein without departing from the spirit and scope of the invention.