bluuebunny/crossref_metadata_2025 huggingface dataset:
A Review of Modern Instrumental Methods of Elemental Analysis of Petroleum Related Material: Part I—Occurrence and Significance of Trace Metals in Petroleum and Lubricants
Authors: Nadkarni RA
Published: March 2009

Almost all elements in the periodic table are found in petroleum products, varying from percent levels for C-H-S to parts per million and parts per billion levels for transition metals. The presence of elements in crude oil is ascribed to its marine animal and vegetative origin. Compared with two other fossil fuels — coal and oil shale — petroleum is a lesser source of environmental pollution. Extensive data on crude oils composition are available. Determination of S, N, V, Ni, and Fe form an integral part of crude assay analysis of oils carried out by all oil companies. Generally it is agreed that V, Ni, and Fe occur as metallo-porphyrins; Hg, Sb, and As as organometallic compounds; Mo and Ge as carboxylic acid salts; and silica and NaCl as colloidal minerals.

The significance of metals either naturally present in crude and gasoline or purposely added to petroleum products is described. Trace metals in used lubricating oils indicate the wear performance of an engine, and can be used as a preventive maintenance check. A number of sample preparation schemes are necessary depending on the analytical technique to be used. This can vary from procedures as simple as dilution for XRF or AAS, to more involved procedures such as oxygen bomb combustion for ion chromatography, or wet ashing for AAS or ICPAES. Frequently, robots are used to speed sample dilution for XRF or ICPAES.

For quality assurance of these analyses, standard reference materials (SRMs) are used. At least three sources of these materials are Alpha Resources, Leco Corporation, and the National Institute of Standards and Technology. SRMs for crude oil, diesel oil, fuel oil, kerosene, lube oil, paraffin oil, and petroleum coke are currently available.
Correlation Between Inductively Coupled Plasma and Rotating Disk Electrode Spark Emission Spectrometry for Used Diesel Engine Oils
Authors: Nygaard D , Bulman F , Alavosus T
Published: March 2009

Fifty used and twenty new diesel engine oils are analyzed by both inductively coupled plasma and rotating disk electrode spark emission spectrometry. The results obtained by the two techniques are statistically correlated for ten wear metals and for four additive elements, and the implications of the correlations are discussed.
Techniques to Improve the Ability of Spectroscopy to Detect Large Wear Particles in Lubricating Oils
Authors: Lukas M , Anderson DP
Published: March 2009

Machine condition monitoring through oil analysis is a proven and cost-effective maintenance management technique. Periodically, however, the ability and need of the analytical techniques to detect large wear particles are questioned. Today there is general consensus as to the maximum wear particle size capability of atomic emission spectrometers (AES) and atomic absorption spectrometers (AAS), but few agree on the ways to improve them. This paper discusses three techniques that can be used to improve the ability of optical emission spectrometers to detect and quantify large wear particles in lubricating oil.

The single spark technique is based on an atomic emission spectrometer readout system that stores the intensity of individual excitation sparks for each element and presents the data as a particle size distribution. The system can operate in real time and provide information on each analysis, or the output can be suppressed and the user alerted only if wear particles exceed a preset size limit. Test data has shown an ability to detect and identify wear particles up to 40 μm in size.

The ashing rotrode technique is based on a sample introduction and analysis system in which the oil sample is deposited on a graphite electrode, then resistively heated to desolvate the oil matrix. The desolvated matrix is subsequently excited by a pulsed D-C arc, and the spectra is analyzed by a polychromator. This technique minimizes matrix effects, enhances spectral sensitivity, and greatly improves detection of large wear particles.

The acid digestion differential technique is based on two analyses of the same oil sample. The sample is analyzed with and without acid to dissolve wear particles. The difference in the two readings indicates the presence of large wear particles.

All three techniques discussed in this paper improve the ability of spectrometric techniques to detect, quantify, and identify wear particles. Capabilities and limitations of each are discussed. The technique of choice varies with the requirements and philosophy of the analytical laboratory.
Precious Metal Assay Analysis of Fresh Reforming Catalyst by X-Ray Fluorescence Spectrometry
Authors: McElroy FC , Mulhall JM
Published: March 2009

Precious metal analysis of fresh reforming catalysts are typically performed by both the catalyst manufacturer and buyer to arrive at a financial settlement on the quantity of metal in each lot of commercial catalyst: Traditional assay methods involve a variety of fire assay or wet chemical acid digestion schemes coupled with gravimetric, colorimetic, or titrimetric measurement for precious metals. Methods must have sufficient precision and accuracy to afford interlaboratory agreement of within one half of one percent relative between the catalyst supplier and purchaser. To meet this requirement many laboratories rely on classical methods. Unfortunately these procedures are labor intensive and time consuming.

X-ray fluorescence has the inherent instrument precision to achieve typical intralaboratory precision of 0.5% RSD on a wide variety of elements and numerous sample types. We have developed an X-ray fluorescence method for the assay quality analysis of fresh reforming catalysts containing platinum, rhenium, and iridium. This method was applied to numerous samples over the past five years.

The XRF method uses chemically assayed fresh catalysts as comparison standards to quantify the X-ray fluorescence response on unknown samples. Samples and standards of the same matrix and nominal elemental concentrations are ground, dried overnight, and then allowed to air equilibrate. Standards and samples are pressed into briquettes with alumina cups in a pellet press to 20 tons. Net counts for each element are collected at the appropriate wavelengths for both standards and samples. Analysis is performed on a minimum of three sample briquettes and four briquettes for each of three standards. The ratio of the net counts to the precious metal concentration on each standard is averaged to obtain a calibration factor. Platinum alone and platinum in combination with other promoter precious metal concentrations are calculated by taking the average sample net counts for each element and dividing by the appropriate calibration factor. Intralaboratory and interlaboratory results are presented showing the applicability of X-ray fluorescence as an assay quality procedure for precious metal analysis.
Energy Dispersive X-Ray Fluorescence Spectrometric Determination of Vanadium, Nickel, and Iron in Petroleum and Petroleum Residua
Authors: Shay JY , Woodward PW
Published: March 2009

Trace metals such as vanadium, nickel, and iron in fluid catalytic cracking feedstocks deposit on the catalyst and adversely affect catalyst activity and product yields. Vanadium compounds can also cause damage to furnace linings and corrosion of boiler tubes or gas turbine blades. A rapid and sensitive analytical method is needed to detect these metals in feedstocks, products, and residua. Such a method using energy dispersive X-ray fluorescence (EDXRF) spectrometry for determination of vanadium, nickel, and iron in petroleum and petroleum residua is described.

In order to eliminate matrix effects, samples containing an internal standard (cobalt) were decomposed by heating with concentrated sulfuric acid and the resulting carbonaceous residua were ashed. X-ray fluorescent spectral intensities of V, Ni, Fe, and Co were measured using established instrumental parameters. Since the Fe Kβ and Co Kα lines overlapped, the slope and the intercept of the ratio of Fe Kα to Fe Kβ intensities from the analysis of ash of several iron standards were used for correction of Co spectral intensities. Sample metal concentrations were determined by comparison of spectral ratios to those of ashed calibration standards. Analytical data obtained by this procedure for National Institute of Standards and Technology (NIST, formerly NBS) Standard Reference Materials (SRMs) 1618, 1634b, and 8505 were in very good agreement with the NIST certified values. The metal contents of petroleum and petroleum residua determined by this EDXRF method also agreed with those obtained by a flame atomic absorption method. This analytical approach could be developed into an ASTM standard method and the scope extended to include determination of other metals.
Improved Performance for Trace Halide Determination in Hydrocarbons
Authors: Ohlson GG , Takahashi Y
Published: March 2009

Microcoulometry has been widely used to measure halides in hydrocarbons. While microcoulometric analysis is well-established, some types of hydrocarbons (i.e., crude oils, heavy fuel oils, hydraulic fluids, and others) require special attention due to their physical and chemical properties. In the past, slow combustion with higher temperatures (1000°C or greater) was recommended; however, sluggish response due to refractory components, the presence of heavy metals, or the rapid aging of the quartz combustion tube under such conditions has made data interpretation difficult at times.

Analysis of heavy hydrocarbons was improved by changing the combustion tube design and adding cupric oxide wire to the combustion outlet zone. With this scheme, it is not necessary to use high furnace outlet temperatures. Combustion efficiency and system response improve, while the effects of deposits and corrosion are greatly reduced. Crude and #6 fuel oils, phosphate ester fluid, and base lube oil additives were tested under these conditions, yielding better recovery and improved precision for some by a factor of three or greater.

A post-combustion scrubber developed for solvent analysis was evaluated for refractory hydrocarbon analysis. It had little effect on the detection limit, but could be used to remove deposits.
Examination of Selected NDE Techniques for Ceramic Composite Components
Authors: Dunyak TJ , Stinchcomb WW , Reifsnider KL
Published: March 2009

Nondestructive techniques are needed to detect defects, monitor the various states of material, and characterize damage development in ceramic matrix composite (CMC) specimens and components. Although some nondestructive examination (NDE) methods yield more information than others, generally no one method will provide all the required information. Therefore, a combination of NDE methods is necessary to fully investigate specimens and components before, during, and after testing.

This paper examines a variety of NDE methods to meet these needs. The investigation covers a wide variety of methods from typical optical microscopy to highly developmental techniques such as acoustoultrasonics and scanning acoustic microscopy. The paper provides an information base on the application of NDE techniques to ceramic composites to assist researchers in planning and selecting NDE methods for CMCs.

The paper is divided into three main sections. The first section briefly describes the fabrication of the specimen and the mechanical test series. The second section contains a discussion of the application of selected NDE methods and a short synopsis of each of the methods examined. The third section summarizes the NDE results in conjunction with the mechanical test results. In this section, a correlation of the initial defects, observed damage development, and failure surface analysis is provided to identify the critical performance limiting defects in chopped fiber-reinforced borosilicate glass tubes.
Nondestructive X-Ray Tomographic Microscopy of Damage in Various Continuous-Fiber Metal Matrix Composites
Authors: Stock SR , Breunig TM , Guvenilir A , Kinney JH , Nichols MC
Published: March 2009

X-ray tomographic microscopy (XTM), a high resolution variant of industrial computed tomography, provides nondestructive, high-resolution “sectioning” of samples and allows three-dimensional mapping of X-ray absorptivity multiple times during an in-situ experiment on a single sample. The capabilities of XTM for damage accumulation studies in composites are described in this paper, with emphasis on what can be accomplished using monochromatic synchrotron radiation. Results are shown for five continuous-fiber metal matrix composites (MMC) (aligned SiC/Al, [02/±45]s SiC/Al, aligned SiC/Ti3Al, aligned SiC/Ti-6Al-4V, and aligned Al2O3/NiAl). The samples' cross-sectional dimensions are approximately 1.5 by 1.5 mm or smaller, and the variation of X-ray absorptivity is measured within each (5.6-μm)3 volume element of the volume studied. An experimental approach for nondestructively quantifying damage evolution with XTM is outlined, and preliminary results are presented for the aligned-fiber SiC/Al MMC. Also discussed are the prospects for improved spatial resolution with XTM and for examining specimens under applied loads and/or with dimensions larger than the current 2 or 3 mm.
Design Parameters of a Serpentine Optical Fiber Bending Transducer for Strain Measurements in Smart Structures
Authors: Demirdogen AC , Houghton JR , Tay AK , Wilson DA , Wood RL
Published: March 2009

A unique optical fiber transducer for measurement of bending strains that can be used for display of distributed strains in a structure is described. A mathematical model for the design of this transducer with circular segments is presented. The attenuation along one 360° segment with respect to bending radius and a biaxial stress field is derived. Analytical results show that the serpentine transducer is most sensitive to curvature of the plane that includes the circular segment. The effects of the bending curvature on a circular segment, when the center of curvature is in the same plane as that of the circular segment, is for the attenuation to average out to produce relatively small net change as a function of curvature.

Experimental results are presented to show the output of net attenuation through the serpentine transducer. Three-point bending tests demonstrate the problem of selection of the initial circular segment radius to avoid the whispering gallery mode of attenuation fluctuation.
Defect Classifications in Composites Using Ultrasonic Nondestructive Evaluation Techniques
Authors: Steiner KV
Published: March 2009

The growing use of advanced composites in structural applications has intensified the need for nondestructive technologies to locate, identify, and classify defects and flaws in composite structures with increasingly complex geometries. Ultrasonic nondestructive testing methods have proven to be successful and reliable in the inspection and certification of composite structures that are scanned by sophisticated, automated, multiaxis robotic systems. Digitizing of the ultrasonic information has introduced powerful computer graphics image enhancement techniques to aid in the interpretation of the results.

Research results of comparative studies are presented that take advantage of advanced robotic scanning and subsequent image enhancement technologies. A variety of ultrasonically detectable defects such as porosity, contaminations, delaminations, fiberor matrix-rich areas, fiber orientation, and impact damage are interrogated. Flaw growth models for fatigue samples are discussed, addressing the flaw criticality issue, a growing area of interest in the characterization of composite structures.
Damage Characterization for a Solid Propellant by an Energetic Approach
Authors: Heuillet P , Neviere R , Nottin JP , Deneuville P
Published: March 2009

An experimental approach is proposed to provide a damage variable for solid rocket propellant. This technique employs cyclic tests to measure an energetic quantity which fulfills the necessary cumulative properties. Basically, the proposed damage variable is defined from measuring the irreversible energy loss, which is dissipated in the dewetting process of particles from the elastomeric binder. Supported by experiments of this latter material in bulk, it is suspected that the macroscopic viscoelastic behavior is induced by a time-dependent local fracture process of the interface.
Effect of Manufacture-Induced Flaws on the Strength of Foam Core Sandwich Beams
Authors: Zenkert D
Published: March 2009

In the manufacture of foam core sandwich structures, the faces are bonded to the core, and blocks of foam core material are bonded to each other in order to obtain the required thickness. Core material blocks are also joined lengthwise in the production of large and/or curved structures, using so called butt joints. However, in the manufacturing process, flaws may occur. Debonding in the adhesive joints acts as cracks, and sharp corners will be the result of an absence of filler material in a butt joint. The present paper deals with methods for the prediction of the reduction in load-bearing capacity of foam core sandwich beams due to these flaws. A fracture mechanics approach is used, including both analytical methods and finite element analysis. Fracture toughness data of the materials and wedge geometries are found from simple specimens. Full-scale tests are performed using beams with prefabricated flaws for verifying the analysis. The predictions agree well with the experimental results. The reduction in load-bearing capacity is as much as between a factor of 1.5 to 4.9 for different geometries and flaw types.
Impact Damage Assessment of Composites
Authors: Girshovich S , Gottesman T , Rosenthal H , Drukker E , Steinberg Y
Published: March 2009

The influence of impact damage on the structural performance of composite laminates was investigated by a joint effort and included nondestructive evaluation (NDE), mechanical testing and analysis. The impacted NASA Industry Standard Compression After Impact test specimen was chosen. Damage characterization incorporated ultrasonic and radiographic methods. Computerized and manual ultrasonic testing from both sides of the test panels provided accurate information on the damaged area. The findings were confirmed by a destructive X-ray microfocus technique combined with an opaque penetrant for damage enhancement. From the NDE data, a simplified damage model was constructed and analyzed for strength and stability. Failure loads and modes were predicted and compared to compression after impact test results. Preliminary tests showed very good agreement.
Modelling of Impact Damage Features in Graphite/Epoxy Laminates
Authors: Chester RJ , Clark G
Published: March 2009

This paper describes recent work in which improved nondestructive evaluation (NDE) techniques for impact damage in graphite/epoxy composites have been used in conjunction with two different approaches to damage modelling to improve prediction of structural response under compressive loading.

Impact-induced delaminations occurring at different interfaces within the laminate exhibit different orientations and sizes. A model has been developed to explain this behavior, in which the forces acting on two adjacent nonparallel plies during impact are considered. Regions in which the model predicts positive peel forces have been shown to correlate closely with actual delaminations in a variety of impact-damaged laminates. The model also considers the role of intraply cracking, which provides boundaries to the impact delaminations and plays a part in forming characteristic delamination/cracking features in the damaged laminate.

Following detailed characterization of the impact-damaged zone using ultrasonic C-scanning and sectioning, experimental models have been produced in which polytetrafluoroethylene (PTFE) inclusions simulate the shape and extent of all the delaminations present in the impactdamaged zone. Compression tests on these specimens lead to failure strengths that are comparable to those of impact-damaged specimens and which are considerably lower than those of specimens containing single PTFE inclusions. These results suggest that the delaminations are more significant than ply cracks or fiber failures in determining the compressive behavior of impact-damaged laminates.

The predictive capability resulting from the modelling aspects of this work and the improvements in inspection methods provide considerable potential for accurate assessment of impactdamaged components for subsequent repair.
Influence of the Stacking Sequence on Fatigue Transverse Ply Cracking in Cross-Ply Laminates
Authors: Henaff-Gardin C , Lafarie-Frenot M-C , Brillaud J , El Mahi A
Published: March 2009

Matrix-cracking mechanisms have been investigated for carbon/epoxy cross-ply laminates. Tension-tension fatigue tests were conducted on two equivalent layups whose only difference consists in the stacking sequence and in the resulting 90° ply thickness. The initiation and development of transverse cracks are characterized. The 90° ply thickness and the loading amplitude appeared to have a strong influence on crack distributions in the specimen and on the propagation rates. A comparison between finite element method (FEM) and analytical results has led us to develop a shear lag analysis in order to estimate the strain energy release rate associated with 90° ply crack formation and growth. Moreover, a fatigue-cracked surface propagation law has been obtained that appears to be independent of the stacking sequence.
Evaluation of Damage Progression in a Composite Material Hip Implant during Long-Term Multiaxial Fatigue
Authors: Gavens AJ , Liao K , Maharaj GR , Jamison RD , Reifsnider KL
Published: March 2009

Evaluation of composite fatigue damage using nondestructive evaluation (NDE) techniques has been documented in the literature. The application of this damage-monitoring capability to a composite hip prosthesis has been examined. Composite hip prostheses were fatigue tested in a bone-simulating, low-modulus fixture and examined for damage using several conventional NDE methods. Radiography and surface replication were able to detect damage in the prostheses. Due to the small volume of damage and the experimental variation in the structural stiffness and acousto-ultrasonic tests, these methods did not provide an adequate indication of damage accumulation. After 15 × 106 cycles, even with visible damage on the prosthesis, no acoustic emission activity was detected. These results reinforce the need for the use of complementary NDE methods when examining composite structures.
Introduction to Food Packaging
Authors: Cage JK
Published: March 2009

The basic principles of packaging to preserve, merchandise, protect, market, and distribute are applied very effectively in the food industry. More recently, food packages have been developed which offer tamper-evident or tamper-resistant features, allow for product preparation, and provide dispensing features and many conveniences such as single serving portions. Often the food product and its package are developed to be an integrated unit such as an aerosol product.

Technological breakthroughs in metals, glass, paperboard, composites, and most especially plastics have provided a multitude of opportunities for improved food packaging. The plastics segment of the packaging industry has shown the most rapid growth for many reasons. Some of the most important are: some plastics can be used in microwave ovens; plastics have a wide range of physical and barrier properties; and plastics offer design capabilities and features not available with other packaging materials.

However, ecological and environmental concerns are growing rapidly, along with federal, state, and local regulations and laws which will have an effect on the whole packaging industry. Further, the demographic changes related to the increased percentage of older consumers will also have significant effects on food packaging in the future.
The Determination of Moisture Stability of a Dynamic System Under Different Environmental Conditions
Authors: Marsh KS , Ambrosio T , Guazzo DM
Published: March 2009

Effervescent tablets defy standard analysis for moisture sensitivity. High humidity conditions cause effervescence with corresponding changes in the tablet composition. However, the time necessary to perform traditional shelf life testing on a product which requires a two-year shelf life was considered too lengthy. An accelerated testing protocol was therefore desirable.

Novel analytical techniques were developed to determine the product's response to humidity changes. Computer modeling was then employed to define product response to two isothermal storage conditions and three dynamic distribution environments in a nonfoil blister package. The results predicted that the two-year shelf life would be achieved.

The product's two-year shelf life was established in three months of research time. The product, Fibre Trim effervescent tablets, became the first effervescent tablet to be introduced in a nonfoil package worldwide.

The computer estimates have since been confirmed with storage studies.
Effect of Sorption of Organic Volatiles on the Mechanical Properties of Sealant Films
Authors: Harte BR , Giacin JR , Imai T , Konczal JB , Hoojjat H
Published: March 2009

The influence of sorption of organic volatiles on the mechanical properties of polymeric sealant films was investigated. Three sealant films were used, a commercial low-density polyethylene, and two developmental films, an ethylene vinyl alcohol copolymer of high ethylene content and a copolyester. Samples of the films were immersed in three different juices (orange juice, apple juice, and tomato juice) for up to 24 days at 22°C. Periodically, film samples were removed from the different juices and the stress-strain properties, heat seal strengths, and impact resistance of the test materials determined as a function of sorbed organic volatile levels or storage time. Statistically significant differences were found in the mechanical properties of the films as a function of sorbant level and storage time. The amount of change varied and was dependent on the film-juice system and the mechanical property evaluated.
High Barrier Plastics Packaging and Ethylene Vinyl Alcohol Resins (a Marriage)
Authors: Schaper EB
Published: March 2009

In 1983, with the introduction of the first multilayer high barrier plastic bottle in the United States, a revolution was started in the food packaging industry. This revolution has gained momentum over the last five years so that today almost any type of food product is a candidate for packaging in a high barrier plastic container. Food products are not the only candidates, however; many nonfood products such as chemicals, health care products, electronic parts, etc. are taking advantage of the excellent cost/performance properties of high barrier plastics packaging. One of the primary reasons for the acceptance and functionality of this type of packaging is ethylene vinyl alcohol copolymer (EVOH) resins.

This paper will review multilayer plastics packaging applications, their markets and economics from 1983 to the present, and why EVOH resins play a very important role in the “packaging revolution.”
Current Practices in the Measurement of Oxygen Transmission Rates of Packaging Films Under Humid Conditions
Authors: Pike L
Published: March 2009

The techniques being used to measure the oxygen transmission rates of packaging films under humid conditions are briefly described and their advantages and disadvantages discussed. The techniques consist of various methods of humidifying the gas streams used in the standard methods for dry gas transmission rate measurements and the controlled humidity “sandwich” method. The new modern controls “H-System,” which was designed especially for this purpose, is also described.

One must choose from the available techniques and equipment based upon the needs and funds available. Only very limited data are available for comparison of the techniques, so accurate statements about precision still cannot be made.
Clinical and Experimental Studies in the Biology of Aseptic Loosening of Joint Arthroplasties and the Role of Polymer Particles
Authors: Goodman SB , Fornasier VL
Published: March 2009

Aseptic loosening is the most common cause of failure of joint arthroplasties. Although the exact pathogenesis of the loosening process is not completely understood, particles of polymethyl methacrylate and polyethylene appear to play a crucial role. This paper summarizes past and current clinical and experimental research on the biology of aseptic loosening of joint arthroplasties and discusses the important role of particulate polymeric debris.
Histopathological Effects of Ultrahigh-Molecular-Weight Polyethylene and Metal Wear Debris in Porous and Cemented Surface Replacements
Authors: Campbell P , Nasser S , Kossovsky N , Amstutz HC
Published: March 2009

The replacement of cement with biological ingrowth systems for fixation has not resolved the problem of aseptic loosening nor that of osteolysis in association with metal and polyethylene wear debris. In order to investigate the role of wear debris in the failure of surface replacements, a histopathological study of ten titanium alloy porous-coated (PSR) and ten cobalt-chrome (Co-Cr) alloy cemented components was conducted. Wear-debris-laden histiocytes (metal and polyethylene) were associated with massive osteolysis in several of the PSR components, but bone loss in the cemented Co-Cr components was confined to localized areas adjacent to the cement membrane. The results of this study suggest that histiocytes activated by the ingestion of fine wear debris are responsible for bone loss. The mechanism of bone loss shown by this “model” is applicable to all joint replacement implant systems where wear debris is generated.
Histomorphological Reaction Patterns of the Bone to Diverse Particulate Implant Materials in Man and Experimental Animals
Authors: Boss JH , Shajrawi I , Soudry M , Mendes DG
Published: March 2009

Implantation of an orthopedic device into or onto bone induces the formation of an interface membrane separating the one from the other. The histological reaction patterns described herein are those occurring in the interface membranes of a cemented arthroplasty, cementless isoelastic arthroplasty, cementless carbon-fiber/polysulfone arthroplasty, intraosseous anchorage site of a carbon-fiber composite ligament, partially biodegradable composite polylactic acid polymer/carbon plate, and stainless steel nail. The tissue response to the introduction of Taurolin into bone is also reported. Under all these circumstances, the morphological findings are rather monotonous, inasmuch as inflammatory, granulomatous, and cicatrizing changes are induced by the implanted foreign materials. The authors suggest that it is not the uniqueness of any one implant component which is responsible for the development of the interface membrane but rather that one or more diverse, nonspecific, biologically indigestible wear particles, released at the bone/implant interface, trigger the self-perpetuating growth of the interface membrane.
Biocompatibility of Polymethyl Methacrylate With and Without Barium Sulfate in the Rat Subcutaneous Air Pouch Model
Authors: Lazarus MD , Cuckler JM , Mitchell J , Schumacher HR , Baker DG , Ducheyne P , Imonitie V
Published: March 2009

A pseudosynovial lining is a characteristic finding at the bone/cement interface of a loose prosthesis. Repeated injection of air into the subcutaneous tissue of a rat results in the formation of a cavity with a lining that shares many histologic and secretory properties with this pseudosynovium. The authors used this model to investigate the differences in biological response to polymethyl methacrylate with and without barium sulfate, and found that the presence of barium sulfate led to a markedly increased inflammatory reaction.
Human Plasma Adsorption to Particulate Arthroplastic Component Materials In Vitro
Authors: Kossovsky N , Feng D , Millett D , Campbell PA
Published: March 2009

A preliminary study of the adsorption of plasma proteins to four commonly used arthroplastic materials was performed. Particulate forms of titanium, cobalt, chromium, and polymethyl methacrylate (PMMA) were incubated with plasma from patients undergoing primary arthroplastic surgery and from patients undergoing revision surgery. The adsorbed proteins were eluted with 2% sodium dodecyl sulfate (SDS) and were separated electrophoretically on Laemmli minigels. The separated protein bands were clustered into five groups based on their molecular weights: <144, 144 to 77, 76 to 43, 42 to 18, and >18 kilodaltons (kD). The number of bands in each group was used as a way of comparing the patterns of adsorption to the different biomaterials. The number of eluted protein bands in the 77 to 145-kD range for cobalt (2.4 ± 1.34 bands) was less than that eluted from titanium (4.40 ± 0.89 bands) and from chromium (4.20 ± 0.045 bands) for both primary and revision plasma. Fewer protein bands were also eluted from cobalt than from chromium, PMMA, and titanium in the 18 to 42-kD range. The authors speculate that, because of cobalt's unique surface characteristics, plasma proteins may show either enhanced or impaired binding. Although this remains to be demonstrated, the results of this study define trends that warrant further investigation.
Use of an Anticollagenase Antibody to Study Synovial Cell Interactions with Particulate Material
Authors: Greis PE , Georgescu HI , Fu FH , Evans CH
Published: March 2009

Wear particles released from synthetic anterior cruciate ligaments (ACLs) have been implicated as mediators of the effusions and synovitis that often follow ACL reconstruction. Particulate material, released as a result of abrasion and device failure, interacts with the synovial lining cells of the knee, causing inflammation, synovial hypertrophy, and cellular activation. This leads to the intraarticular release of degradative enzymes such as collagenase. By using collagenasespecific antiserum, the in vitro activation of synovial cells by small particles was observed immunofluorescently. This technique provided direct visual evidence of cellular activation as the result of the phagocytosis of particles of latex, carbon, or Dacron. Particles 23 μm and less in diameter were easily phagocytosed by the svnovial cells, resulting in the production of collagenase. This method permits observation of the interactions between individual cells and particles of specific sizes, shapes, and other physical properties. It should thus prove useful in future studies of the importance of these parameters in eliciting cellular responses to particles.
Evaluation of Cure and Durability Aspects of Building Sealants
Authors: Beech J , Beasley J
Published: March 2009

Durability characteristics of sealants have been assessed by measuring the changes in certain key properties (“performance indices”) after exposure of specimens to natural and to artificial weathering. A major problem in such assessments is the long duration of the cure processes of sealants after specimens are made up: in some cases these extend to 12 months or longer, during which periods continuing changes in sealant properties are observed.

This paper reports the results of a controlled study which attempts to distinguish between those changes in properties due to the continuing cure process, and those caused by changes in the sealant due to exposure to various environments which simulate the effects of weather. The latter included laboratory regimes in which the sealant samples were exposed to elevated temperature (70°C), both with and without UV(B) radiation; to artificial weathering including UV(B) radiation and water condensation; and exposure to weather in the UK, for up to 12 months.

The study involves two phases, in the first of which, reported here, freshly-prepared sealant specimens were exposed to ageing or to weather before tensile testing. In the second phase the same procedures were followed using specimens which had first been stored under standard conditions in the laboratory for 12 months.

Some results of the first phase of this study of cure and durability characteristics are given in this paper, and discussed in relation to the development of test methods for the assessment of the durability of sealants. Modulus values measured on sealant samples after exposure to artificial weathering and to heat ageing in the laboratory show highly-significant correlations with data from naturally-weathered samples.
A Screening Evaluation of Surface Cleaning Fluids and Their Effects Upon the Adhesion of Various Weathersealing Sealants
Authors: O'Brien WR , Berg DT
Published: March 2009

A low volatile silicone cleaning/priming solution was evaluated in comparison with a variety of organic cleaning solvents and one organic solvent based primer. The evaluation also reviewed a wide variety of substrates, sealants, and surface contaminations. In virtually all situations the use of the silicone cleaner/primer alternative to organic solvents actually helped promote sealant adhesion better than all other solvents evaluated.
Mortar Block Surface Preparation and ASTM C 794
Authors: Webb WG
Published: March 2009

Historically, the results of ASTM C 794 Adhesion-In-Pee1 tests have been subject to high variation, especially in tests on mortar where results from different laboratories were compared. This experiment focuses on one potential source of error, the method used to prepare the surface of the mortar block. Five different techniques were evaluated with three generically distinct sealant types all intended for use on concrete and mortar. The procedures described in ASTM C 794 were followed as closely as possible. The results are evaluated for differences in precision which can be attributed to the substrate.
Adhesion of Silicone Sealants to Organic-Coated Aluminium
Authors: Gutowski VWS , Russell L , Cerra A
Published: March 2009

The integrity of a structurally glazed building envelope depends on the strength of adhesion at several interfaces, e.g. glass- glass coating, glass coating-silicone sealant, silicon sealant-substrate coating, substrate coating-primer, primer-substrate.

Frequently, the frame and cladding are aluminium alloys which are either anodised or finished with an organic coating to satisfy aesthetic and/or long-term corrosion resistance requirements.

In this paper, the mechanism of adhesion between organic-coated aluminium and silicone sealants is analysed. The sealants investigated are neutral-, alkaline-, and acid-cured, 1-part RTV silicones as well as 2-part RTV silicones, all commercially available. The organic coatings investigated are powder and wet-coated polyester, PVF2 (polyvinylidene flouride), acrylic and siliconised finishes, also all commercially available products.

It is shown that the strength of adhesion between any silicone sealant and the organic-coated substrate, as well as the extent of adhesive failure, depend on the substrate surface properties as quantified by the non-dispersive component of the substrate surface energy, γn-d. A typical relationship is shown to exist for strength v. γn-d and [%] adhesive failure v. γn-d.

Finally it is shown that the organic-coated substrates used in structural glazing can be assessed for their potential bondability with silicone sealants by determining the non-dispersive component of their surface energy. This technique is described in detail in this paper.
Performance of a Modified Sealant Fillet Detail
Authors: Hoigard KR , Kudder RJ
Published: March 2009

A high-rise building experiencing curtainwall leakage was targeted for remedial repairs to correct the problem. The cost of a conventional repair using a new mullion cover and sealant detail was judged to be prohibitively high, and an alternate design was sought. The alternate design selected required no new extrusions and incorporated a modified fillet bead with a foam bond-breaking tape. As this was an unproven detail, a test program was initiated to compare its performance to that of the mullion cover repair. Both repair designs were subjected to the equivalent of five years expansion and contraction at twice the anticipated extension range. Both designs performed without adhesive or cohesive failure of the sealants observed during the test period. The alternate design was judged to be comparable in extension performance and a viable substitute for the more expensive mullion cover repair.
Stress Distributions in Highway Joint Seals
Authors: Weisgerber FE , Wang C-P
Published: March 2009

Highway joint seals, and some other butt seals using elastomeric materials, have displayed a high incidence of adhesion failure. An incremental finite element analysis method has been used to determine the magnitudes and distributions of interfacial stresses, treating the material as a low-modulus viscoelastic material in a state of plane strain. The results show that the magnitudes of both normal and shear adhesive stresses are very high at specific points on the contact surface, much higher than the average normal stress predicted by simpler analysis methods. The depth to width ratio for the seal, the rate at which strain is applied, and the relaxation rate of the material are all shown to have significant effect upon the stress magnitudes.
Comparison of an Insulating Glass Polyurethane Sealant Based on Hydroxylated Polybutadiene Liquid Polymer and a Poysulfide Based One
Authors: Hubin-Eschger PJ
Published: March 2009

Most performances of a two-part commercial sealant for insulating glass based on hydroxylated polybutadiene are reviewed and compared with those shown by a conventionnal two-part sealant based on polysulfide. First are examined the handling properties. Then are discussed the adhesion and mechanical characteristics. The ageing effect due to both actions of water and ultra-violet radiations and the permeability to argon are studied on standard insulating glass specimens.
Climate and Performance of Elastomeric Wall Coatings
Authors: Elfring WH , Rosano WJ
Published: March 2009

Elastomeric wall coatings attempt to protect exterior concrete masonry walls by minimizing water penetration through surface cracks. In contrast to traditional paints, waterborne elastomeric wall coatings used in construction and restoration, are designed as functional crack-bridging membranes. These coatings are highly formulated materials containing pigments, extenders, and a resin binder. The key to the formulation is the binder, which provides the properties that enable the material to elongate and compress repeatedly without flowing apart or embrittling and cracking. A formulation's ability to perform as an elastomeric building material is strongly affected by climatic conditions. An elastomeric coating with a long product life in one geographic location may not hold up as well in another. The coating manufacturer must choose an appropriate binder and tailor his formulation to suit the climate where it will be used in order for the coating to have a long life cycle. Studies of crack width as a function of wall surface temperature have led to a simple model that allows us to predict building movement in different climates. Plotting crack width against wall surface temperature enables us to produce a building movement profile. By factoring in fatigue data for various types of coatings over moving cracks, we can begin to assess how binder type and changes in formulation impact product life cycle. Studies and tests such as these should lead to better understanding on the part of raw material suppliers, formulators, and contractors on how to design, test, and apply high performance elastomeric coatings which are long-lasting and durable.
Replacement of Solvent Based Glazing Compounds with High Performance Water Based Acrylics
Authors: Potts KB
Published: March 2009

Historically waterborne systems have had somewhat lower performance than most solventborne products. However, with the increased emphasis on environmental concerns and EPA mandated reduction in volatile organic content, window manufacturers are looking at alternate sealants. New advances in the waterborne acrylic polymers have led to the development of waterborne acrylic sealants with performance characteristics that meet or exceed most solvent-based systems. These sealants show excellent cold temperature flexibility, little age hardening, good U.V. resistance and excellent wet and dry adhesion. Compared to most solvent based compounds, water-based acrylics offer superior compatibility with all types of insulating glass sealants. In addition solvent emissions are eliminated and clean-up is accomplished with water only. These systems exhibit easy gunnability and application properties, and can be used on all existing gunning equipment.
Silicone Rubber Latex Sealants
Authors: Liles DT , Shephard NE
Published: March 2009

Silicone rubber latex is an aqueous dispersion of silicone rubber particles that forms elastomers upon evaporation of water. Silicone rubber latex is formulated into sealants by incorporating fillers, pigmnets and other additives. Silicone rubber latex is prepared by crosslinking emulsions of poly(dimethylsiloxane) using a tin catalyst. Properties of silicone rubber latex sealants differ in some respects from those of traditional RTV silicone sealants. This paper describes preparation of silicone rubber latex and silicone rubber latex sealants. Properties of both uncured and cured silicone rubber latex sealant are also discussed.
Deep Space Network 70-Meter Antenna Elevation Bearing Failure Investigation
Authors: DiGiorgio AS , Hsieh C
Published: March 2009

Antennas for the United States Deep Space Network (DSN) are vital to the success of the space program in providing tracking and communication with deep space probes. The three 70-meter antennas, located in California, Spain, and Australia, are the largest and most important link of the DSN network capability. These antennas were originally constructed at 64 meters in diameter, but were subsequently modified to 70-meter diameter to support the Neptune and Uranus encounters by the Voyager spacecraft. An increase in load on the supporting bearings accompanied this modification. It was determined that the bearings possessed the capacity to support this additional load; however, the load was not uniformly distributed.

One of the elevation bearings on the antenna in Spain collapsed on December 13, 1989. This bearing functioned on the 70-meter antenna over an 18 year period. Four SKF 231/600 CAK C1 W33 SRB bearings support the DSN antenna assemblies which rotate very slowly over 160° once or twice daily. Bearing rolling contact components were manufactured from AISI 52100 steel. Rolling elements were produced with axially through-bore holes to facilitate the heat treat process. Failure investigation established that fatigue cracks initiated at the surfaces of center holes, progressed to fracture which led to lockup and culminated in overload of associated bearing components. Due to advancements in material development since the 1970s, solid rollers may be satisfactorily produced without center holes which can introduce sources for stress risers.

Antenna operation was promptly restored by replacing the damaged bearing with a spare. Load equalization and nondestructive inspection of the remaining bearings were conducted. Fracture mechanics analysis was performed to estimate the remaining life of the bearings. Due to the critical nature of the DSN antennas, a recommendation was made to replace existing bearings with current state of the art solid roller bearings.
Jet Fuel Thermal Stability—A Specification Writer's Viewpoint
Authors: Batchelor GL
Published: March 2009

This paper presents, in a philosophical and technical context, a specification writer's viewpoint on jet fuel thermal stability. The specification writer must specify his limits for jet fuel thermal stability within the constraints of quantifiable measures of jet fuel oxidative processes, constraints of current and advanced aircraft engine design, and constraints of cost effective jet fuel manufacture. It is the interaction of these diverse factors which debars the specification writer from merely accepting the dictates of historical testing patterns.