bluuebunny/crossref_metadata_2025 huggingface dataset:
Formation of Cobalt Silicides in Arsenic Implanted Cobalt on Silicon System
Authors: Sitaram A.R. , Murarka S.P.
Published: March 2011

The importance of self aligned cobalt disilicide technology for gate and interconnection, and contact metallization cannot be overemphasized. Simultaneously, the concept of forming shallow junctions by using the metal or silicide layer as a dopant source is gaining prominence. In this work, we will present and discuss the results of the effect of arsenic, implanted into cobalt films on silicon, on the Co-Si reaction. Arsenic redistribution during the reaction, both during furnace annealing and RTA, and the effect of ion implantation and dose and energy will also be included.
Luminescence of Alizarin and its Metal Complexes
Authors: Larson Londa J. , Zink Jeffrey I.
Published: March 2011

The red/near-infrared emission spectra of alizarin (1,2-dihydroxyanthraquinonone), the potassium salt of alizarin and the aluminum and zinc complexes of alizarin in the solid state are reported. The emission is assigned to an alizarin localized transition from an in-plane nonbonding orbital delocalized over the anthraquinone rings to a predominantly π* C=O acceptor orbital (nπ* ligand localized excited state). The cobalt, nickel and copper complexes do not emit from their nπ* excited state. In these complexes, metal centered d-d excited states which lie lower in energy than the ligand localized state effectively deactivate the luminescence.
Applications of Environmental Scanning Electron Microscopy in Art Conservation and Archaeology
Authors: Stulik Dusan , Doehne Eric
Published: March 2011

The principles of Environmental Scanning Electron Microscopy (E-SEM) are explained and discussed. The performance of the E-SEM compares favorably with the performance of traditional SEM instruments. This new technology has significant advantages in art conservation and archaeology. In this paper we describe several pilot studies which explored potential uses of the E-SEM. Electron micrographs recorded from moist, outgassing, and difficult to coat samples are presented, together with X-ray spectra recorded from uncoated samples of electrically nonconductive materials.
Glass-Sensors: Assessment of Complex Corrosive Stresses in Conservation Research
Authors: Fuchs Dieter R. , RÖmich Hannelore , Schmidt Helmut
Published: March 2011

Glass sensors, based on K-Ca-silicate glass chips, with a low durability against corrosive stresses, offer a new method for assessing the complex environmental stress situation of monuments and pieces of art. The easy-tohandle technique is able to detect the combined impact of climatic stresses, pollution and microbiological effects as well as synergetic interactions.

The chemical composition of the sensitive glasses enables judgements within few months. This way long-term estimates can be obtained without costly long-term investigations.

The corrosion progress is determined by microscopy and IR-spectroscopy of the weathered glass sensor surfaces. The sensors are already operating in the field of stained glass window preservation. They monitor the efficiency of different kinds of external protective glazings and the remaining stresses from the in-door environment of cathedrals.
Evaluation in Situ of the State of Deterioration of Monumental Stones by Non-Destructive Ultrasonic Techniques.
Authors: Montoto M. , Calleja L. , Perez B. , Esbert R.M.
Published: March 2011

A non-destructive ultrasonic procedure has been developed for evaluating in-situ the relative deterioration of monumental stones. Ultrasonic waves are injected into the rock and they are registered, processed and petrophysically interpreted after travelling through it. The procedure applied to a Spanish Monastery (San Lorenzo de El Escorial, Madrid) built with a granitic rock is described.

The following methodology was applied: in-situ categorization of the observable deterioration forms, sampling in the original quarries, laboratory ageing tests and continuous ultrasonic monitoring, in-situ data acquisition, evaluation of the ultrasonic parameters by signal processing and stepwise discriminant analysis. All that information is petrophysically interpreted for an appropriate assignation of the in-situ studied masonry blocks to the categorized deterioration degrees.

Final in-situ results from the Monastery of El Escorial are here presented. Among the studied ultrasonic parameters energy is the most useful of all of them and velocity the least.
Mechanical Stresses Generated by Crystallization of Salts Inside Treated and Non-Treated Monumental Stones; Monitoring and Interpretation by Acoustic Emission / Microseismic Activity.
Authors: Esbert R.M. , Montoto M. , Río L. M. Suárez Del , Argandoña V. G. Ruiz De , Grossi C.M.
Published: March 2011

The crystallization of salts in building stones is one of the most common and severe deteriorating phenomencndeveloped on Historic Buildings. To evaluate their mechanical effects in treated and non-treated stones, experimental salt crystallization tests and the monitoring of the corresponding acoustic emission / microseismic activity, AE/MS, have been planned.

Salt crystallization tests have therefore been performed on a high porosity (30%) limestone used in the building of the Cathedral of Murcia (Spain). Each test consisted of 11 and 20 cycles (for the non-treated and treated specimens, respectively) of immersion of specimens in salt solution (14% Na2SO4. 10H2O) for 4 h., drying in an oven at 60 °C for 14 h. and final cooling at room temperature for 6 h. The treated specimens were consolidated by total immersion in ethyl silicate -Tegovakon V- and protected with a water repellent, oligomeric polysiloxane -Tegosivin HL- 100-, (both from Th. Goldschmidt, FRG).

The AE/MS, was monitored in the 100-300 KHz range. The preliminary results show a very different AE/MS behaviour between the non-treated and the treated specimens.
Technology and Weathering of Mesoamerican Jades as Guides to Authenticity
Authors: Garza-Valdes Leoncio A.
Published: March 2011

The beauty of a carved pre-Columbian jade defies description. Unfortunately, thousands of fake jade pieces are in museums and private collections. In the study of authenticity, it is necessary to scientifically analyze the surface, observing the changes produced by reactions with the environment, mostly aqueous soil mixtures.
The Critical Role of Technological Analysis for Prehistoric Anthropological Inference
Authors: Rollefson Gary O.
Published: March 2011

Prehistoric archaeology has profited enormously from the expanding role of technological examination of artifactual materials, particularly in the past couple of decades. Indeed, the rapid growth of materials sciences studies has evidently begun to outpace the capacity of many prejistoric archaeologists to accomodate the results of technological analyses into anthropological models to explain perceived changes in the prehistoric archaeological record. The sheer numbers of published technological reports, which increasingly appear in a growing number of specialized journals and other publications, account for some of the communications lag among prehistorians and smaterials scientists. But long-held and persistent myths and “hearsay” evidence also contribute to a widening gap between relevant data and critical evaluation.

The case study presented below compares scenarios that purport to explain striking contrasts in the northern and southern parts of the Levant during the middle part of the Neolithic period, particularly from ca. 6,500-5,000 b.c. One hypothesis (climatic change) is briefly dismissed; the other hinges principally on the environmental implications of plaster production that characterized the cultures of the region. The “collapse” of the southern Levantine settlements is understandable when the specific requirements of lime plaster manufacture are taken into account, while the conditions for the persistence of long-term site continuity in the northern Levant are clear under the less pressing environmental demands of gypsum plaster production.
Ancient High-Strength Ceramics: Fritted Faience Bracelet Manufacture at Harappa (Pakistan), Ca. 2300-1800 B.C.
Authors: McCarthy Blythe , Vandiver Pamela
Published: March 2011

Unlike most ancient faience, which consists of a quite porous and weak body coated with a glassy glaze, much Harappan faience has a quite dense body with a continuous glassy phase and a relatively thin skin of glaze. A multiple-step grinding and fritting process of manufacture was used to make the finely ground, uniformly blue-green and other colored bodies. Intentional additions of glass frit and clay are postulated. The Harappan faience bodies are particularly strong, compared with contemporaneous faience from Southwest Asia and Egypt, because Harappan faience is more dense, because differential thermal contraction during cooling places the continuous glassy phase in compression, and perhaps also due to crack deflection toughening. A similar technology is not found in Egypt until much later during the New Kingdom about 1450 B.C., and then only glass is added.

The socio-cultural reasons for the development of such a specialized technology probably resides in the properties required of the particular type of artifact in which this technology is most often found, that is, bracelets. Bracelets, or bangles, were worn on arms and legs; most often several were worn at a time. Such use required the bracelets to meet criteria of increased abrasion resistance and impact strength, and thus an innovative technology was developed to meet these needs.
Accelerator Radiocarbon Measurements of Artistic Artifacts
Authors: Donahue D. J. , Jull A. J. T. , Toolin L. J. , Barnhill J. , Lange T.
Published: March 2011

The use of a particle accelerator to measure the 14C content of carbon-containing materials is briefly described. The application of the method to the determination of the age of some artistic artifacts is discussed.
The Reconstructiton of Ancient Ceramic Technology Through the Comparative Analysis of Ancient and Contemporary Potters′ Materials: A Case Study from the Central Tiber Valley of Italy
Authors: Peña J. Theodore
Published: March 2011

This paper presents the results of a program of mineralogical analysis aimed at the elucidation of raw material acquisition and paste preparation practices among Roman-period potters in the Orte/Vasanello area of the central Tiber Valley of Italy. A study of modern folk potters at Vasanello revealed a complex pattern of clay utilization. A selection of local clays, pottery produced by Vasanello potters, and ceramics from two Roman ceramic production sites was subjected to mineralogical analysis (x-ray diffraction, petrographic) for purposes of comparison. The results indicate that similar clay sources were exploited by potters in both periods, and that the materials obtained from these were likely employed for similar functional varieties of pottery.
Wheelmade or Wheel-Finished? Interpretation of ‘Wheelmarks’ on Pottery
Authors: Henrickson Robert C.
Published: March 2011

Analysis of patterns of breakage and xeroradiographs have shown that ‘wheelmarks’ provide an incomplete and potentially misleading diagnostic for forming methods. The location and distribution of such marks over the entire vessel is crucial. Patterns of breakage reveal the characteristic patterns of weakness in the vessel fabric left by each type of forming method. Examination of both the overall patterns and surfaces of breaks in relation to the vessel profile aids reconstruction of the original forming process. Selective xeroradiography aid this interpretation. Despite the ubiquity and extent of ‘wheelmarks’ on Godin III painted buff ware vessels (bowls and closed shapes), patterns of breakage and xeroradiography demonstrate limited but persistent use of true throwing of small vessels on a potter's wheel (western Iran, 2600-1400 B.C.). All others were built using combinations of hand-forming methods and finished on a tournette.
Methodological Trends in Investigations into Ancient Pottery From the Levant
Authors: Edwards Ian
Published: March 2011

The Australian excavations at Pella in Jordan under the guidance of Professor Basil Hennessy (Sydney University, Australia) have over the past 13 years demonstrated the current range of methodologies used in pottery studies in the Levant. One feature of the Australian field team has been the continuing inclusion of this writer from the Archaeology Research Unit, Victoria College, Melbourne (ARU) as a ceramic technologist/potter.

The ARU at Victoria College, which operates together with a practical pottery workshop and an Advanced Ceramic Mlaterials Development Unit, uses a multidisciplinary team approach to look at excavated ancient pottery not primarily as archaeological artefacts but as pottery.

Within the ARU Dr Ralph Segnit handles the mineralogy, Dr John Hamilton the geology, while Robert Hughan, to whom I am indebted for the testing reported here, handles the ceramic chemistry and fracture mechanics aspects. My role as both a ceramic technologist involved in field archaeology and as a trained potter, is to participate in generating the questions which will form the focus of the team's investigations.
A Review of Mid-Second Millennium B.C. Egyptian Glass Technology at Tell El-Amarna
Authors: Vandiver Pamela , Swann Charles , Cranmer David
Published: March 2011

In 1891 and 1892 Sir Flinders Petrie excavated glass in various stages of processing from the palace dumps at the fourteenth century B.C. site of Tell el-Amarna, a city built by artisans practicing the highest quality possible in their crafts in order to adorn the new capitol of Tutankhaman and thereby legitimize his rule(1). In order to learn more about the making and working of this glass, we analyzed samples in several stages of processing for composition, processing temperature, viscosity, extent of crystal growth and microscopic evidence of forming methods. Our findings accord with microscopic evidence from complete vessels, an unpublished manuscript on glass finds by the excavator, Sir Flinders Petrie(2) and previous work of the British glass technologist, W.E.S. Turner(3).
An Historical Mullite Fiber-Reinforced Ceramic Composite: Characterization of the ‘Wootz’ Crucible Refractory
Authors: Lowe Thelma L. , Merk Nima , Thomas Gareth
Published: March 2011

Since at least the sixteenth century, the ‘wootz’ ultra-high carbon white cast-iron ingot was produced in India by melting or carburising iron in a crucible. This ingot was forged into sword blades of so-called ‘Damascus’ steel. The charged crucible was fired in a long (24 hour) single cycle at high temperature (1150-1250°C) in a strongly reducing atmosphere. Raw materials for the refractory vessel are clay and ‘coked’ rice husks. At high temperatures, two phases reinforce the glassy matrix - cristobalite relics of rice husks and a network of mullite crystals. This paper characterizes the microstructure and chemistry of the mullite network in the glassy matrix by means of a combination of techniques: optical microscopy, XRD, SEM, TEM with EDS, and HREM.
Technical Analysis of Sculpture for Economic Studies of Past Societies
Authors: Reedy Chandra L.
Published: March 2011

Art historical research related to Himalayan copper-based sculpture has concentrated on its religious, historical, and cultural context; questions of style, regional provenance, and chronology have also been important issues. The relationship of art production to economic considerations, and the relative role of economics versus aesthetics in the choice of casting and decorating alternatives, have received little attention. Although these are indeed difficult problems to address, they are nevertheless interesting ones that deserve some attempts at analysis.
A Technical and Analytical Study of Two Silver Plates in the Collection of the J.Paul Getty Museum
Authors: Scott David
Published: March 2011

Two silver plates in the collection of the J. Paul Getty Museum were studied by non-destructive x-ray fluorescence spectroscopy, inductively-coupled plasma-mass spectrometry, xradiography, optical metallography, electron microprobe analysis and lead isotopic composition. One plate depicts a scene of philosophical discourse (the ‘Philosopher plate’) and the other an aged fisherman with his catch (the ‘Fisherman plate’). Both plates have designs on the fronts made not by repousse but by a combination of working and annealing followed by carving to shape. Technical and analytical results are described which support the attribution of a date in the early centuries AD. There are several differences between the two plates, such as the way in which the footring has been made and attached. Both, however, have thick corrosion crusts and have suffered intergranular corrosion. Determination of trace elements, such as zinc and gold, together with the method of manufacture suggests that both plates are ancient. Lead isotopic data for the two plates is different, with the Philosopher plate showing a close relationship to other Byzantine objects, even though a Renaissance date had been suggested.
Casting Doubt: Economic and Technological Considerations Regarding Metal Casting in the Ancient World
Authors: Ogden Jack. M.
Published: March 2011

The lost wax casting technique is almost impossible to use if the finished object must be of a specified weight or must utilize all of a given batch of metal. This basic fact helps to explain why Old World ancient gold jewelry, particularly of Hellenistic, Roman and Byzantine origin, is almost always-hand wrought rather than cast. Similar considerations relate to the manufacture of copper-alloy weights or other objects which appear to be of pre-determined weight.
Cation-Selective Reagents for Conservation Treatments
Authors: Chartier Duane R.
Published: March 2011

Crown ethers, cryptands, polyphenols, and several other reagents are known to have high specificity for various cationic species. These reagents have great potential for application in general conservation problems of selective cleaning, desalination, stain removal and reversal of treatments in conservation. They are remarkably more effective in metal ion complexation than the more common chelates (usually only EDTA is used for conservation applications) which are used generally with little regard for selectivity.

The advantages of a selective reagent are both its minimal effect on other species and its maximal cost-effectiveness. Most of the macrocyclic chelates are noutral specion that are lipophilic and solubilize metal ions (of the correct size) in non-aqueous media as well as water. Therefore, polar organic solvents may be used for water-sensitive treatments.

Research has been designed to assess the use of cationselective materials both in the laboratory and in situ. The potential of these compounds to expand the range and the safe execution of existing and new conservation treatments is excellent.
Energy Dispersive X-Ray Spectrometry of Gold-Silver-Copper Standards for Comparison with Historic Gold Objects
Authors: White S.M. , Koestler R.J. , Blair C. , Indictor N.
Published: March 2011

Seven ternary mixtures of gold(80-95%)-silver(4-15%)-copper(1-15%) were prepared as standards for the determination of elemental composition by energy dispersive X-ray spectrometry (EDS). Two geometric forms (flat and oblate) of the standards were prepared for comparison to the analyses of historic gold objects. Surface analyses were performed. Polished sections of the standards were also analysed Comparison between two methods for collecting EDS data is reported. The analyses are discussed in terms of developing a generalized methodology for estimating elemental composition of museum artifacts.
Events in the Historical Development of Weights and Money
Authors: Wiedemann H.G. , Bayer G.
Published: March 2011

The characteristic features and importance of weights and money in different cultures will be illustrated with examples from ancient Egypt, Babylon, Israel and China. In most of these cultures there was a gradual change of the names of weights to the names of money. The weight stones and figures were calibrated with seeds of barley or wheat in the Mediterranean and seeds of millet or rice in China.

The weight of such seeds is rather constant and varies little under different climatic conditions as could be proved from our own investigations. Later these granular weight units were replaced by solid weight standards (e.g. stones or figures) which again were calibrated with counted seeds.

Different materials were used such as basalt, agate, bronze, lead, silver and gold. The metallic weights gradually developed into coins and were used sometimes as weight and as money like the silver Shekel. Chemical analysis with EDAX and X-ray diffraction analysis were carried out on some of these ancient materials. The use of this combination of methods also allowed to distinguish between genuine, original materials and imitations.
The Interpretation of Textile Production and Use by High and Low Status Caddoan Groups
Authors: Kuttruff Jenna Tedrick
Published: March 2011

This paper demonstrates the application of technical studies of the fragmented remains of archaeological textiles to the reconstruction of past textile technologies and to the interpretation of the cultural phenomenon of status differentiation. The analyses of archaeological textile remains recovered from Caddoan burial contexts (Mississippian period) in Oklahoma, Arkansas, and Missouri provided information for the interpretation of differential production and use of textiles by high and low status groups within that prehistoric society of the southeastern United States. The research is based upon the characterization of specific textile attributes and burial context. The data sets utilized in the textile analyses include fabric structure, fabric scale, edge treatment, patterning, design, coloration, yarn structure, and fibers. Production complexity for each textile is assessed and then ranked using a recently developed textile production complexity index. Those specific textile attributes that appear to be most highly associated with status differences are identified using two different statistical procedures. Technological differences as well as textile utilization patterns between high and low groups are explored.
The Effect of VikaneTm on the Stability of Cellulosic and Ligneous Materials -- Measurement of Deterioration by Chemical and Physical Methods
Authors: Burgess Helen D. , Binnie Nancy E.
Published: March 2011

VikaneTM (sulphuryl fluoride) is a commercial fumigant[1] which is used for the control of pests in museum collections. This paper summarizes the results obtained through an investigation of the effect of VikaneTM on twenty-five paper and textile samples. Samples chosen were representative of artifacts present in North American collections (cotton, linen, jute, and wood pulp fibres, from 1622 to present).

The effect of the fumigation treatment has been evaluated by chemical and physical analyses: (1) Acidity -- surface pH, cold extracted pH, total acid (iodometric titration), (2) Oxidative and Hydrolytic Degradation - viscometric average degree of polymerization, carbonyl content (hydrazone derivatization), (3) and Fumigant Residues (specific ion electrode). Analysis of unfumigated and fumigated samples was carried out before and after accelerated ageing (70°C and 50% relative humidity) in order to estimate the long term stability of fumigated samples.

The data obtained show that commercial grade VikaneTM degrades cellulosic and ligneous fibres. A second set of experiments on two fibre types using a new experimental grade of VikaneTM gave significantly less degradation. The presentation of this work will concentrate upon a general scientific interpretation of results.

It is anticipated that the conclusions will be applicable to a broad range of artifacts.
Corrosion and Past“Protective “Treatments of the Benin “Bronzes“ in the National Museum of African Art
Authors: Schrenk Janet L.
Published: March 2011

The Benin (Nigeria) “bronzes“1, like many museum objects have been subjected to a variety of coatings and other surface treatments by museums, dealers and private collectors since their removal from Africa during the British Punitive Expedition of 1897. Today these surfaces are discolored, corroded, saturated with “oils and waxes” and generally do not represent the original West African aesthetic. Corrosion often occurs below the “protective” surface coating, despite the apparent visual stability of the surfaces.

Samples of coatings and corrosion from the Benin “bronzes” in the National Museum of African Art have been examined by XRD, SEM-EDZ FT-IR and CLC. Results include the frequent observation of fatty acid salts of copper and other alloy metals.
Use of FT-IR in the Conservation of Twentieth Century Objects
Authors: Shearer Cretchen L. , Doyal Sherry
Published: March 2011

The application of Fourier transform infrared spectroscopy (FT..IR) to the identification of early semi-synthetic and synthetic plastics is discussed. The sample technique is described. Three materials, natural rubber, cellulose nitrate (celluloid) and cellulose acetate are discussed and examples of identification of these materials are presented.
New High Temperature Multipurpose Applicator
Authors: Tinga W.R. , Tian B.Q. , Voss W.A.G.
Published: March 2011

Using a new microwave small-sample quasi-TEM mode applicator, heating rates up to 700°C/s were obtained for various oxides and ceramic materials at 915 MHz. Design details are presented. A 60 W solid state power source is used to supply the microwave energy and control material temperature. Temperature is measured using either infrared or thermocouple techniques. The applicator is a TEM resonator with a TM mode gap field modified by a hollow variable radius center conductor acting as a waveguide below or near cutoff. This design creates a microwave materials analyzer equally suited for high or low temperature material studies, is scaleable to different frequencies and can be used to measure dielectric properties up to a temperature of at least 1500°C. Solid, granular, liquid, gas or plasma samples can be accommodated. By using microwave transparent refractory materials around the sample, temperatures greater than 15000 C can be maintained in some materials. Perturbation of the resonator by the inserted material causes a frequency shift which is nearly linear over a permittivity range of at least 1–70. This is an order of magnitude improvement over the conventional perturbation approach. For microwave joining or sintering of ceramic rods, the energy can be concentrated into a symmetrical hot zone as narrow as 1 mm.
The Grounded Dielectric Slab as a Planar Leaky-Wave Applicator.
Authors: D'ambrosio G. , Ferrara G. , Massa R.
Published: March 2011

It is well known that a leaky wave in free space may show a decay rate even less than zero, or, in other words, its amplitude may grow instead of decay [1,2,3,4]. The above behaviour is very attractive from the point of view of deep processing of materials [5,6]; thus we extended the leaky-wave antenna theory to the lossy (half) space case and analyzed in detail the channel guide applicator [7,8,9].
Computer Modeling and Numerical Techniques for Quantifying Microwave Interactions with Materials
Authors: Iskander Magdy F.
Published: March 2011

Computer modeling and numerical techniques provide an attractive, accurate, fast, and cost-effective means for calculating power deposition patterns and temperature distributions in materials during and after their processing using microwaves. Besides giving information on heating rates and patterns, numerical modeling and computational techniques may provide valuable information that may result in better control and optimization of theheating process. The optimum material/insulation combination for improved uniformity and efficiency of microwave sintering of ceramics and the development of procedures that may prevent problems such as temperature runaways are typical examples of attainable benefits from numerical modeling and computational techniques.
Temperature Profiles in a Finite Element Thermal Model of the Prostate Region Under Hyperthermia Treatment
Authors: Chatterjee Indira , Adams Roy E. , Saniei Namdar
Published: March 2011

The detailed transient temperature distribution in an inhomogeneous model of a cross section through the prostate region of the human body undergoing hyperthermia treatment forcancer has been calculated. The finite element method has been used to solve the bioheattransfer equation. A commercially available finite element software package called ANSYS® has been adapted to the present problem.

The model consists of 523 triangular elements and incorporates a tumor in the prostate.The hyperthermia device under test is an Annular Phased Array consisting of dipole antennas. The model is surrounded by a bolus of deionized water. The calculated electromagnetic energy distribution is input into the bioheat transfer equation and the resulting temperature distributions calculated.

The increase in blood perfusion rates due to heating is incorporated into the model. Detailed transient temperature profiles in the finite element model are presented for various values of blood perfusion rates in the tumor and surrounding tissues. It is observed that the Annular Phased Array is effective in raising the temperature of the tumor to therapeutic values.
Evapuration Model of the Near Surface Microwave Discharge
Authors: Bykuv Yu.V. , Erieiaeev A.U. , Sorukin A.A.
Published: March 2011

Many technological applications based on the use of intensive microwave radiation are connected with high temperature material processing. As a rule the microwave power being absorbed in the material must provide heating of the processed zone up to rather high temperatures (> 100º c) within fairly small time intervals. hese requirementsare dictated either by the nature of the process ( surface transformation hardening, joining ceramics and metals, cutting materials ) or by necessity to provide sufficiently large process output ( coating of materials, joining of dielectrics, melting, etc.). The upper value uf the exploited radiation intensity is limited by effects of gas breakdown near the treated surface. The considerable part of microwave rad.ation can be absorbed and dispersed by the discharge plasma, hence microwave energy supplied to the material significantly decreases.
Diffusion-Controlled Processes in Microwave-Fired Oxide Ceramics
Authors: Janney Mark A. , Kimrey Hal D.
Published: March 2011

Processing oxide-based ceramics using microwave heating leads to a number of unexpected results, which can only be interpreted in terms of enhanced diffusion. Enhanced sintering has been observed in alumina and zirconia. Accelerated grain growth in dense, hot-pressed alumina has been demonstrated. Increased diffusion coefficients have been observed for diffusion of oxygen in sapphire. As yet, a satisfactory theory to account for these phenomena has not been developed. This paper reviews the experimental work conducted at the Oak Ridge National Laboratory during the past four years on the processing of oxides in both 2.45 and 28 GHz microwave furnaces.
The Microwave Heating Behaviour of Metallic-Insulator Composite Systes
Authors: Lorenson Claude P. , Ball Mel D. , Herzig Ralph , Shaw Hamish
Published: March 2011

The microwave heating behaviour of composite systems is of considerable interest for theprocessing of ceramics or the creation of materials with interesting dielectric properties. In this investigation, the heating response of different mixtures of metallic and insulating powders is described. The heating rate as a function of metal type, mass fraction and powder types will be presented for pressed pellet samples.

From the results, three distinct heating regimes have been identified. At low temperatures. induced electric currents cause the metal particles to heat. As the temperature increases, exothermic oxidation of the metal powder particles increases the heating rate. Eventually, the insulating powder (alumina) begins to absorb microwave energy more efficiently and this dominates the high temperature behaviour. The relative importance of thesethree effects for different temperatures depends on the particular powders which are used.
Effect of Green Microstructure and Processing Variables on the Microwave Sintering of Alumina
Authors: Dé Arindam , Ahmad Iftikhar , Whitney E. Dow , Clark David E.
Published: March 2011

The concept of 'hybrid heating with microwave (MW) energy at 2.45 GHZ.'for ultra rapid sintering of alumina is being introduced. This technique is a combination of MW - materual interaction as well as conventional radiant/conduction mechanisms, and facilitates the attainment of perhaps, the highest possible heating rates in a multimode MW cavity at 2.45 GJZz. (1500ºC in 120 sees.). Rapid sintering of pure.undoped alumina with this novel techniQue culminates in uniform, homogeneous microstructures and mechanical property enhancements vis-a-vis conventional fast firing.

The role of green microstructure (particle size) on MW(hybrid) heating and processing variables (temperature, time) on the MW (hybrid) heating phenomena vs. conventional fast firing were investigated. Hybrid heated samples showed accelerated densification with comparable grain sizes when compared with the conventionally fast fired samples. The effectof particle size on the microwave (hybrid) heating phenomena was found to be analogous to conventional sintering.
Microwave Drying of Borosilicate Gels
Authors: Surapanani Srinivas , Mullins Michael E. , Cornilsen B.C.
Published: March 2011

Microwave processing was carried out on SiO2 -B2O3 solutions and gels prepared by sol-gel methods. Monolithic gels were prepared from alcoholic solutions of trimethylborate and tetraethylorthosilicate using a two-step hydrolysis process. A novel technique of Liquid State Processing (LSP) was employed for the first time, and it was found to be faster and more effective than the conventional processing techniques. The structural evolution of the dried products was followed using FTIR. The effect of processing was examined via surface area analysis (BET), electron microscopy, and FTIR. The microwave drying has been compared with conventional oven drying and vacuum drying techniques. Shorter processing times, improved microstructures, and unique properties have been obtained.
Microwave Polymerization of Embedding Resins for Biological/Biomedical Elecron Microscopy
Authors: Giammara B.L. , Birch D.J. , Harper D.O.
Published: March 2011

The use of microwave energies for polymerization of epoxy and other commercially available resins, used routinely in electron microscopy methodologies, shows promise for diagnostic pathology where rapid methods can be crucial. Many desirable embedment properties, such as specimen infiltration, color, hardness, rough trimming, and ability to stain, are necesssary. The properties necessary for cutting 1 micron semithin sections and 700 Angstrom ultrathin sections (that can withstand pentration by a 100 kV electron beam for image formation) must be maintained.

In this study, six epoxy resins and one unsaturated polyester resin were used, the latter in a variety of recipes. Each formulation was subjected to microwave power levels from 400 to 700 W for 1 to 15 minutes. Selected specimen embedments tested well and significantly reduced traditional convection oven polymerization time from two days to a few minutes.
Increased Candida Demonstrated in Subgingival Plaques of Aids Patients by Microwave-Accelerated Silver Staining
Authors: Hanker Jacob S. , Kutcher Mark J. , Burkes E. Jefferson , Greco George W. , Hopfer Roy L. , Hamamoto Darryl T. , Webster William P. , Yates Peggy E. , Beck James D. , Giammara Beverly L.
Published: March 2011

Acute periodontal lesions generally respond to conventional therapy. In AIDS patients, however, further deterioration is the usual consequence. Candida albicans(CA) lesions of the oral mucosa have been observed in 88% of AIDS patients; 59% of male homosexual and IV drug abuser oral candidiasis patients subsequently developed AIDS. Indeed HIV may be hard to find in AIDS patients in whom CA lesions are very prominent.

Rapid reproducible silver stains have been developed in our laboratories to detect Gram-negative bacteria, fungi and protozoa. They demonstrate these microorganisms by the microwave-accelerated metallization of the aldehydes produced in their surface carbohydrates or lipopolysaccharides after periodic acid oxidation (Giammara and Hanker, US Patent No. 4,690,901, 1987; Sigma Diagnostics Kit No. HT-100). We thought that these stains might be useful to demonstrate by microscopy the large numbers of CA which culture studies had suggested were present in subgingival plaque at atypical periodontal disease sites of AIDS patients. Direct staining of plaque smears and their evaluation under the light microscope could be done in much less time than that required for culture. Any equivocal microorganisms could be positively identified as CA by immediate examination of the slide or coverslip by scanning electron microscopy. Although our PATS reaction was more valuable for identifying Gram-negative bacteria especially spirochetes and for studying substructure of CA and their epiphytic interactions with bacteria, the SIGMA DIAGNOSTICS Silver Stain HT-100 was much easier to use for rating CA concentration in disease sites. This test was applied to subgingival plaque smears from 28 periodontal disease sites of 22 HIV-seronegative patients and 45 sites of 12 HIV-seropositive patients. After staining, the smears were examined and scored (Davenport Index). None of the 12 HIVseropositive patients but 15 of the 22 HIV-seronegative patients had a score of zero at all sites. The score ranged from 0 (no CA) to 3 (large numbers of CA in all fields). In the seropositive patients the median score was 2 while in the seronegative group it was 0.

The much higher scores obtained in specimens from periodontal disease sites of the AIDS patients suggest that this simple rapid test might be valuable for screening individuals and indicating those requiring further testing or monitoring for AIDS.
Image Analysis Method to Count Silver-Stained Candida in Aids Patients' Subgingival Plaques
Authors: Hanker Jacob S. , Patel Hinesh B. , Giammara Beverly L. , Von Der Heiden Juergen
Published: March 2011

Computer-assisted microscopic image analysis of silverstained subgingival plaque smears was shown to be far more dependable and reproducible than subjective scoring or rating by visual inspection to estimate the amounts of Candida 4ibicans(CA) present. High CA counts in subgingival plaques from atypical periodontal diseased sites could suggest that an individual be tested or monitored further for AIDS. This is especially the case if the individual is in a high risk group or if the CA count cannot be ascribed to immunosuppression resulting from diabetes, corticosteroid or broad-spectrum antibiotic therapy, cancer chemotherapy or blood transfusion for hemophilia. In many such situations this simple, rapid procedure may be useful in screening for AIDS when serologic procedures for the HIV virus may be equivocal.
The Possibilities of Material Processing by Intense Millimeter - Wave Radiation
Authors: Bykov YU. V. , Gol'denberg A.F L. , Flyagin V. A.
Published: March 2011

1. Powerful sources of millimeter wavelength (MMW) radiation are developed nowadays for plasma investigation, particularly for thermonuclear plasma heating. Powerful oscillators for plasma heating - gyrotrons - at wavelengths down to 2 mm with output of several hundreds kilowatt at CW operation and over 1 MW at pulsed operation (pulse duration up to `1 s) are created or being created.1 The existence of CW multi kilowatt gyrotrons allows for new possibilities for material processing. The MMW range is situated at the end of the microwave range close to infrared and naturally allows applications either in the multimode microwave-oven manner or in the form of wave beam energy fluxes similar to laser radiation. Gyrotrons are close to technological lasers from the view-point of high flux densities up to `106W/cm2. By their efficiency (`40%), gyrotrons are among the most effective electromagnetic devices and significantly exceed technological lasers in efficiency as well as in CW outputs. So gyrotrons can be used for various material transformation processes requiring great amounts of energy such as plasma chemistry2 and processing of solid materials.
Processing of Polymers and Polymer Composites In a Microwave Applicator
Authors: Hawley Martin C. , Wei Jianghua
Published: March 2011

Polymers and polymer composites have been processed In a cylindrical resonant microwave applicator at a frequency of 2.45GHz. Stoichlometric mixtures of two epoxy/amine systems, DGEBA (Diglycidyl Ether of Bisphenol A)/DDS (4,4'-Diaminodiphenyl Sulfone) and DGEBA/mPDA(m-Phenylene Diamine), were microwave and thermally cured Isothermally using a thin film technique. FTIR was used to determine the extent of cure. Increased reaction rates were observed In microwave cure when compared to those of thermal cure. The rate Increase due to microwave effects was much greater for the DGEBA/DDS system than for DGEBA/mPDA. Also, crossply and unidirectional 24-ply and 72-ply graphite/epoxy laminates(AS4/3501-6 prepreg, Hercules Corp.). were processed using microwave radiation. The flexural properties of the microwave processed composites were strongly dependent on the resonant heating mode. Comparable flexural properties were obtained for the unpressurized microwave processed composites and the pressurized autoclave processed composites. Proper controlled-hybrid modes are required to process composites of high mechanical properties. The procedures for obtaining these controlled-hybrid modes are described.
Electromagnetic Processing of Polymers: I. Basic Concepts and Molecular Design of The Macromolecules
Authors: Hedrick J. C. , Lewis D. A. , Ward T. C. , Mcgrath J. E.
Published: March 2011

Microwave processing has been utilized to process thermosetting polymeric materials. Specifically, fundamental studies relating epoxy network generation to processing conditions have been investigated in a tunable cylindrical cavity operating at a frequency of 2.45 GHz. These studies demonstrate that fully cured networks can be generated in ten minutes with the retention of good mechanical properties. Furthermore, toughened epoxy systems which utilize carefully designed amine terminated poly(arylene ether sulfone) thermoplastics as reactive oligomers have resulted in novel phase separated morphologies. In fact, it has been demonstrated that the morphology in these multiphase systems can actually be controlled by utilizing microwave processing. Bismaleimide toughened systems, devised by similar strategies, have demonstrated a 10–20 fold reduction in the time required to achieve full cure.
Microwave Enhancement of Chemical and Physical Reactions
Authors: Fanslow Glenn E.
Published: March 2011

Examples of the effects of microwave processing are presented that suggest that microwave ‘heating’ creates higher excitation levels and increased chemical and physical reactions within a material than would be expected if the only change that had been produced by the microwaves was a rise in temperature. The examples include a chemical coal-cleaning process. the destruction of coronene in alcohol, heating of high-temperature superconducting compounds. and a microwaveinduced photovoltaic effect.
Electromagnetic Processing of Polymers: II. Quantitative Investigations of Microwave Processed Thermoplastics (Microwave Calorimetry)
Authors: Chen M. , Zumbrum M. A. , Hedrick J. C. , Mcgrath J. E. , Ward T. C.
Published: March 2011

The microwave heatability of various thermoplastic polymers was investigated. The concept of microwave calorimetry was proposed to quantitatively illustrate how viscoelastic behavior controlled microwave heatability. Specifically, heating rate as a function of sample temperature revealed a distinct maximum which was identified as the Tg at 2.45 GHz. The critical temperature, Tc, necessary for rapid microwave heating was identified by drawing a tangent to the heating rate curve and extrapolating to a critical value at zero heating rate. In separate experiments, low frequency (100 kHz) dielectric measurements were made which show the frequency dependence of Tg by means of Arrhenius activation energy plots. In general, the larger the activation energy, the closer the critical heating temperature, TC, was to the Tg determined by DSC. The smaller the activation energy, the further dielectric loss shifted with increased frequency so that Tc was very far from Tg determined by DSC.
Dielectric Properties Measurements and Data
Authors: Carpenter Joseph A.
Published: March 2011

This paper reviews measurement techniques and sources of data for the dielectric constant and loss factor of solid materials. Accurate values of such properties are basic to intelligent design of materials processing schemes utilizing electromagnetic energy. Emphasis is on techniques and data for these properties in the “microwave” range of frequencies of roughly 108 to 1011 Hz and at elevated temperatures.
Microwave Materials Dielectric Measurements
Authors: Purinton Don , Stiborek Leon
Published: March 2011

Texas Instruments Defense Systems and Electronics Group develops radars, missile systems, infra-red systems and electronic systems for the Defense Department. Materials having special microwave properties are needed for radar systems, missile systems that home on microwave emissions, microwave emitter locator systems, and jamming systems. The microwave materials appear in the form of antennas, lenses, radomes, windows, dielectric loading materials, potting materials, dielectric transmission lines, microwave absorbing materials, adhesives, sealants, coatings, and foams. Naturally, the complex permittivity and permeability of these materials need to be known to enhance their application and control their properties in manufacturing. Texas Instruments has a microwave materials test laboratory that includes permittivity and permeability measurements as well as physical and thermal properties. The samples come in many different forms, measurement at different frequencies are needed and the electrical properties cover a wide span (conductors to dielectrics and foams to ferrites). For this reason, many different methods of dielectric and magnetic measurement are used. These various methods will be discussed below.
Microwave Dielectric Properties of Elastomers Containing Particulate Metal Fillers
Authors: Helme Barry G.M.
Published: March 2011

Elastomers have been manufactured containing varying concentrations of particles of Ag/Al, Ag/Cu, Ag/Ni, Ag/glass (G3), Ni/graphite, Ni, and Ag. Their dielectric and microwave properties have been measured between 0.4 GHz and 40 GHz and at temperatures between ambient and 100°C. The filler particles are small relative to the microwave wavelength but larger than the skin depth. Sheets of these elastomers of up to 2 mm thickness gave been subjected to cyclical stretching of up to 40% elongation and up to 10° cycles. The microwave properties have been measured as a function of numbers of stretching cycles and composition of elastomer. Some correlations were found between the composition, the microwave properties and the number of stretch cycles completed.

It was found in general that repeated stretching degraded the initially high conductivity of the loaded elastomers. This effect was also revealed by the increase in microwave transmissivity through the sheets, and a decrease in reflectivity. Formulations of elastomer-metal particle mix have recently been produced which have a microwave transmissivity more Phan 80 dB below the incident signal, for a 2 mm thick sample, even after 106 stretching cycles of 20% elongation. This property is of great value for the use of the elastomer as a reflective microwave shield.