bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Toxicity of Hydrogen Chloride and of the Smoke Generated by Poly (Vinyl Chloride), Including Effects on Various Animal Species, and the Implications for Fire Safety
Authors: Hinderer RK , Hirschler MM 
Published: March 2009

Toxicity of smoke is only one of many factors determining the hazard or the risk resulting if a product were involved in a fire in a specific scenario. Other factors include: amount of smoke (i.e., concentration of combustion products in the atmosphere), rate and quantity of heat release, mass loss rate, and flame spread rate, as well as such “environmental” factors as ignition source characteristics, fire detection and suppression devices, building occupancy, and code enforcement. A factor almost specific to the smoke generated from burning poly (vinyl chloride) (PVC) is the decay of hydrogen chloride (HCl) by reaction with building surfaces. The values of smoke toxic potency measured will also be affected by a number of parameters, including combustion mode, exposure mode, toxicological end point, and statistical analysis of results.
A crucial factor, often overlooked, is the choice of an animal model appropriate as a surrogate for man, and its validation. Test animals are frequently chosen on the basis of convenience, cost, or other characteristics (e.g., sensitivity) rather than because of their similarity to man. This is particularly important in combustion toxicology, where one test species may not be a good model for all the major combustion products generated. Thus, comparisons of materials producing different major combustion products must be approached with caution to ensure that any apparent differences encountered in tests are not simply an artifact of test species.
Over recent years, increasing evidence has surfaced that some rodent species are poor models for the toxic response of man to irritant gases or to smoke-containing irritants. Studies on HCl (as a pure gas) and on the smoke generated from the burning of PVC have indicated that mice are much more sensitive than rats. More importantly, they are much more sensitive than primates. It has also been established that rats are a good model for primates in terms of the lethal effects of irritant products. Although primates have survived 15-min exposures to 10 000 ppm of HCl, 2500 ppm is lethal to mice. Moreover, under the same exposure conditions, mice will die at PVC smoke levels four to seven times lower and HCl levels seven to ten times lower than those at which rats will. In contrast, lethal doses of asphyxiants such as carbon monoxide (CO) are similar in rats and mice.
These results indicate that the response of the mouse significantly overestimates the toxic potency of HCl and of PVC smoke to man.
Performance Testing for the Corrosivity of Smoke
Authors: Ryan JD , Babrauskas V , O'Neill TJ , Hirschler MM 
Published: March 2009

The corrosivity of combustion products has arisen as an issue for both product manufacturers and standards bodies. While many industries can have concerns in this area, electronic communications and control equipment are especially vulnerable to the problem. The best way to manage the smoke corrosivity issue is to avoid a fire. In the event a fire does occur, a number of actions must be taken. An important consideration is that the materials and products used should have been chosen with due consideration of their corrosion-causing potential. To do this requires a suitable corrosivity test.
It has traditionally been assumed that smoke corrosivity is directly correlated to the emission of acid gases. The results of recent experiments have shown that materials which do not release acid gases can, nevertheless, cause corrosion of metal surfaces, as determined by metal loss. In addition, for electrical equipment there are two other types of related nonthermal damage from combustion products which must be considered, viz., ohmic bridging and degradation of contacts.
Laboratory tests proposed to date to measure the corrosive effects of combustion products all have significant deficiencies: some methods are not performance-based at all and are merely tests for pH. In others, unrealistic specimen heating or unrealistic exposure targets are used. To facilitate the development of a better test, a series of criteria have been developed. A specific test method was evolved from these criteria. The method is performance-based and incorporates realistic fire heating conditions.
Fractographic and Metallographic Study of the Initiation of Brittle Fracture in Weldments
Authors: Harrison PL , Abson DJ , Jones AR , Sparkes DJ 
Published: March 2009

A technique is described for establishing the microstructural features associated with the initiation of brittle fracture in weld metal and heat-affected zone (HAZ) crack-tip opening displacement (CTOD) test specimens. The technique involves detailed optical and scanning electron microscope examination of fractographic features to establish the local directions of fracture propagation at various locations on the fracture surface. This information is used to trace fracture propagation back to the region of initiation. In many instances, the precise initiating feature can be located and identified. Once identified, the fracture initiation position is marked and the specimen sectioned through this point to allow the region in which fracture initiated to be examined metallographically and related to the surrounding microstructure. Details of the technique are discussed.
Examination of steel weld metal and HAZ regions has revealed nonmetallic inclusions, pearlite colonies, second-phase regions (martensite, retained austenite, or carbide), and localized regions of intergranular fracture as the initiating features. The significance of these findings is considered with regard both to the size of features at which cleavage fracture initiates and to scatter in CTOD values.
The Determination of Calcium and Magnesium Carbonates in Soils and Aggregates
Authors: Choquet F , Ista E , Verhasselt AF 
Published: March 2009

The determination of carbonates in soils and aggregates through the measurement of the “loss on ignition” by calcination at 1000°C does not make it possible to discriminate between calcium carbonate, magnesium carbonate, and the double carbonate of calcium and magnesium (“dolomite”).
The measured value may also include the crystallization water and constitutional water of certain compounds as well as any organic matter contained in the samples.
The operation procedure described in the paper is based on the hot acid attack of a test portion of the sample to disengage the carbon dioxide, which is caught in a titrated mixed solution of barium hydroxide and potassium hydroxide. In the acid attack solution, the calcium and magnesium ions are determined by complexometry (possibly by atomic emission or absorption).
The advantage of the method lies in the interpretation of the results. A comparison of these with the theoretical contents calculated for calcium carbonate, magnesium carbonate, and the double carbonate of calcium and magnesium generally makes it possible to discriminate between the various probable carbonates of the analyzed sample. In some cases, the presence of other calcium and magnesium salts can be demonstrated. A number of concrete and experienced examples are presented.
A Modified Shear Strength Formulation for Swelling Clay Soils
Authors: Chatterji PK , Morgenstern NR 
Published: March 2009

Physico-chemical forces of repulsion and attraction exist in swelling or active clay-water systems. A modified shear strength formulation that extends the classical Terzaghi effective stress relationship to include physico-chemical forces is proposed in this paper.
Residual shear strength comparisons were carried out for five carefully controlled, large-strain direct-shear tests on Na-montmorillonite before and after leaching with distilled water and under constant overall volume conditions. These tests indicated that the volume change and residual shear strength characteristics of Na-montmorillonite are governed by the true effective stress, σn*, defined in the modified effective stress relationship as the difference between the total stress, σn, and the summation of pore water pressure, uw, and the net physico-chemical forces of repulsion and attraction (R - A). Additional data available in the literature on residual strength of swelling clay minerals also appear to support the modified strength formulation.
Actual measurements of overall (R - A) forces during leaching of the samples appeared to agree well with theoretical estimation of the net physico-chemical forces.
Material Characterization by Thermomechanical Analysis: Industrial Applications
Authors: Riga AT , Collins EA 
Published: March 2009

Thermomechanical analysis (TMA) has been used to study a wide spectrum of materials over a broad range of temperatures in our laboratories. Polymers, motor oil-wax composites, ceramics, alloys, and metals have been studied from -100 to 600°C. The TMA properties that have been measured are the glass transition temperature, softening point, coefficients of linear expansion, heat deflection temperatures, creep modulus (compliance) and relaxation, degree of cure, viscoelastic behavior, dilatometric properties, melting temperature, Curie, and Neel magnetic transition temperatures and properties.
Polymer cure has been studied and is indicated by variations in the glass transition temperature and increased with heat cycling. A good correlation exists between ASTM Vicat softening temperatures and heat deflection temperatures under load with TMA transition temperatures, which approximate strength and Tg. A scheme has been developed to rank commercial polymers based on their creep modulus and creep recovery. There is a good correlation between the TMA creep properties and the known tensile properties of commercial polymers.
Additive-treated oil forms short stubby wax crystals, which lead to a low creep modulus oil-wax composite at -60°C. This soft composite (gel) melts at a depressed temperature. These TMA properties have been related to low-temperature pumpability and engine performance.
The critical magnetic transition temperatures (Curie and Neel) of a number of ceramics and alloys have been determined by TMA. There is a good correlation between the TMA, differential scanning calorimetry (DSC), and literature critical magnetic temperatures. The mechanism responsible for magnetic changes in the paramagnetic state has been elucidated from TMA expansion rates and DSC exothermicity.
Elasticity Characterization of Materials During Thermal Treatment by Thermal Mechanical Analysis
Authors: Wiedemann HG , Riesen R , Boller A 
Published: March 2009

The viscoelastic behavior of natural and synthetic materials changes during thermal treatment. Thermomechanical analysis (TMA) is the method to determine these mechanical properties directly as a function of time and temperature. Depending on the selected measuring mode either the expansivity (dilatometry), the viscous flow (penetrometry), or the elastic behavior can be investigated. Young's modulus is calculated from flexure and compressive measurements.
To give an overview of these possibilities thermoplastic polymers, poly(methyl methacrylate) (PMMA) and polyethyleneterephthalate (PET), and rubber have been analyzed. The solid transition of α-β quartz revealed a minimum of the Modulus of Elasticity during the transition. Flexure measurements of wood specimens during degradation show the different elastic regions.
Glass Transition Determination by Thermomechanical Analysis, a Dynamic Mechanical Analyzer, and a Differential Scanning Calorimeter
Authors: Cassel B , Twombly B 
Published: March 2009

A suitable specimen was selected to compare the glass transition measurement by several thermal analysis techniques. The specimen, an epoxy composite, was analyzed by Thermal mechanical analysis (TMA) using three different methods, including flexure, expansion, and stress relief, as a function of temperature. A dynamic mechanical analyzer (DMA) was then performed at three frequencies. A portion of the specimen was then selected for differential scanning calorimeter (DSC) analysis. Special care was taken to ensure that the specimen pre-treatment was identical and that thermal lag errors were corrected for, so that a direct glass transition comparison could be made between analytical techniques.
The best agreement in Tg values between the various measurement methods was obtained between: DSC heat flow midpoint; TMA onset of expansion, flexure or stress relief; and the onset of the storage modulus for DMA data taken at 0.1 Hz. These were all within one degree of 122°C. The best correlations with the DSC and TMA data to be obtained from a 1-Hz DMA run was that of the onset of the loss modulus peak (121.7°C). The methods employed are described, and the results discussed.
High-Power Transmission Through Step-Index, Multimode Fibers
Authors: Setchell RE , Meeks KD , Trott WM , Klingsporn P , Berry DM 
Published: March 2009

Motivated by interest in optical firing systems for initiating explosives, laser-induced damage thresholds have been investigated in step-index, multimode fibers having pure fused silica cores. A compact, multimode Nd/YAG laser operated at a pulsewidth of 16 ns was used for the experiments. The focusing geometry for introducing the beam into the fiber was chosen to avoid damage along the core/cladding interface as observed in previous studies. Five lots of twenty fibers each were tested, with polishing steps varied between successive lots to produce improved finishes on the fiber end surfaces. Each fiber was subjected to a sequence of progressively increasing energy densities up to a value more than 80 J/cm2. Initial damage was monitored by observing scattered HeNe laser light from the fiber faces using magnified video cameras.
The majority of the fibers damaged initially at the rear fiber face, once a “laser conditioning” process at the front fiber face was completed. In this process, a visible plasma was generated at the front face for one or more laser shots. Rather than produce progressive damage at the front surface, this process apparently improved the surface finish in nearly all cases, resulting in improved resistance to damage. Other modes of damage along the fiber length were observed either at locations of handling stresses or at the location of highest static tensile stress corresponding to the fiber's minimum bend radius. A fraction of the fibers in each lot never damaged, and this fraction increased as the successive lots were tested. The fibers that did not damage in the final lot were subjected to an additional series of laser shots at the maximum input conditions, and the majority still did not damage. These results, together with some insights into the dominant damage processes suggested by previous studies, are encouraging in terms of realizing high damage thresholds in this type of optical fiber. However, several important areas for further study are indicated.
Ion-Exchange Strengthening of High Average Power Phosphate Laser Glass
Authors: Lee HC , Meissner HE 
Published: March 2009

Thermal stress induced fracture limits the power output of high average power glass laser slabs1. The fracture of laser glass is initiated by the onset of unstable propagation of subsurface microcracks in which local tensile stress exceeds the critical level. The production of subsurface flaws is inevitable for a standard high precision fabrication process. Applying a compressive stress surface layer can be used to counterbalance the thermal tensile stress imposed upon the surface during operation. We have developed an ion-exchange process submerging the phosphate glass into a mixed alkali nitrate salt melt. An ionic size differential induces a compressive layer of tens of microns. The process avoids water corrosion and preserves the finished optical surface quality during ion-exchange. Furthermore, we have optimized the process taking into account network relaxation as well as ion-exchanged concentration profile. To characterize the surface compressive stress, we have employed a biaxial flexure bending test. We have found that a finished HAP-4 laser glass with a tensile breaking strength of 200MPa can be strengthened to twice its original strength, namely 400MPa.
The process has been scaled up to production in which large laser glass slabs or most other phosphate glass can be treated routinely. We have strengthened polished HAP-4 slabs(42cm × 14cm × 1cm) to up to twice their original thermal shock resistance without deteriorating their optical surface quality.
The Effects of Polishing Materials on the Laser Damage Threshold of Optical Coatings
Authors: Crase R 
Published: March 2009

This paper reports the effects of polishing material on the laser damage threshold of optical coatings. Two identical sets of BK-7 glass windows were polished to a laser quality surface finish. One set was polished with cerium dioxide (CeO2) and the second set was polished with a soft zirconia (ZrO2).
Samples of each type were coated with electron beam evaporated dielectric coatings. After coating, the samples were then tested to determine their relative damage threshold. The results for each polish type were then compared. Implications for the use of zirconia as an alternative polishing material for high power laser optics is presented.
Damage Resistant Optics for a Mega-Joule Solid-State Laser
Authors: Campbell JH , Rainer F , Kozlowski M , Wolfe CR , Thomas I , Milanovich F 
Published: March 2009

Research on Inertial Confinement Fusion (ICF) has progressed rapidly in the past several years. As a consequence, LLNL is developing plans to upgrade the current 120 kj solid state (Nd+3-phosphate glass) Nova laser to a 1.5 to 2 megajoule system with the goal of achieving fusion ignition. The design of the planned Nova Upgrade is briefly discussed.
Because of recent improvements in the damage resistance of optical materials it is now technically and economically feasible to build a megajoule-class solid state laser. Specifically, the damage threshold of Nd+3-doped phosphate laser glass, multilayer dielectric coatings, and non-linear optical crystals (e.g., KDP) have been dramatically improved. These materials now meet the fluence requirements for a 1.5–2 MJ Nd3+-glass laser operating at 1054 and 351 nm and at a pulse length of 3 ns. The recent improvements in damage thresholds are reviewed; threshold data at both 1064 and 355 nm and the measured pulse length scaling are presented.
Crack-Mouth Displacements for Semielliptical Surface Cracks Subjected to Remote Tension and Bending Loads
Authors: Raju IS , Newman JC , Atluri SN 
Published: March 2009

The exact analytical solution for an embedded elliptical crack in an infinite body subjected to arbitrary loading was used in conjunction with the finite element alternating method to obtain crack-mouth-opening displacements (CMOD) for surface cracks in finite plates subjected to remote tension. Identical surface-crack configurations were also analyzed with the finite element method using 20-noded element for plates subjected to both remote tension and bending. The CMODs from these two methods generally agreed within a few percent of each other. Comparisons made with experimental results obtained from surface cracks in welded aluminum alloy specimens subjected to tension also showed good agreement.
Empirical equations were developed for CMOD for a wide range of surface-crack shapes and sizes subjected to tension and bending loads. These equations were obtained by modifying the Green-Sneddon exact solution for an elliptical crack in an infinite body to account for finite boundary effects. These equations should be useful in monitoring surface-crack growth in tests and in developing complete crack-face-displacement equations for use in three-dimensional weight-function methods.
Application of Micromechanical Models to the Prediction of Ductile Fracture
Authors: Sun D-Z , Kienzler R , Voss B , Schmitt W 
Published: March 2009

The ductile fracture behavior of different specimens is analyzed by continuum damage-mechanics techniques. A model introduced by Gurson and modified by Needleman and Tvergaard has been implemented in the finite element program package, ADINA. The damage parameters of the model are measured and calculated from smooth tension tests, and the characteristic material distance is estimated from compact tension experiments.
A steel, ASTM A710, and a weld metal for the steel, ASTM A508, are investigated. The damage parameters determined from the smooth bars are used to predict the deformation and fracture behavior of notched round bars and of sidegrooved compact specimens. For the weld metal, a side-grooved WOL-X-specimen is also simulated. In every case, a satisfactory agreement of prediction and experiment is observed.
In order to investigate the influence of the stress state (constraint) in cracked specimens, a series of numerical computations of different specimen geometries and loading situations is performed utilizing the same set of parameters of the ASTM A710 steel. The slopes of the predicted J-resistance curves increase with increasing ratio of tension versus bending load and with decreasing relative crack length.
Online Access to Worldwide Sources of Materials Performance Data--1991 Update on the Materials Property Data Network (MPD Network)
Authors: Kaufman JG 
Published: March 2009

The National Materials Property Data Network, Inc., or MPD Network, is a not-for-profit service for the international engineering and material science communities with the mission of providing single-point online access to reliable performance data for materials and for joints in those materials. MPD Network is the result of a cooperative approach to answering the critical need for better access to numeric/factual data that is being carried forward in association with a number of technical societies, government laboratories, universities, and more than 50 sponsors from private industry.
The MPD Network features direct access to numeric and factual databases, easy-to-use software for the occasional, non-professional searcher, and a metadata system to aid in dealing with the varied terminology, materials nomenclature, units, and abbreviations typical of this field. Users may download information to whatever PC, CD-ROM, or mainframe data management systems they employ in their internal system.
A pilot MPD Network system was developed in 1986–1988 in a joint program with the National Institute for Science and Technology (NIST), formerly the National Bureau of Standards (NBS), the Department of Energy (DOE), Lawrence Berkeley Laboratories (LBL), and Stanford University based upon the NIST technology and was used as the research system and for obtaining user feedback. The production MPD Network began operations in January 1991, on STN International, the worldwide scientific and technical information network.
The major features of the MPD Network system are • Direct access to numeric material property databases • Single point access to many sources • User-oriented menu interface to help you locate specific data • Integrated thesaurus to help deal with confusing terminology and nomenclature • Integrated directory of additional material property databases
This update includes background material on the types of data and databases included on the MPD Network and on the menu interface that makes the system useful to end-user engineers and scientists.