bluuebunny/crossref_metadata_2025 huggingface dataset:
Identification and Quantification of Volatile Organic Compounds Using Systematic Single-Ion Chromatograms
Authors: Tsuchiya Y , Kanabus-Kaminska JM
Published: March 2009

In order to determine the background level of volatile organic compounds (VOCs) in Canadian indoor air, a method of identification and quantification at a level of 0.3 μg/m3 using systematic single-ion chromatograms (SICs) has been developed. The compounds selected for measurement included several halogenated compounds, oxygen compounds, terpenes, and C8 to C16 n-alkanes. Air samples were taken in 3-layered sorbent tubes (glass beads, Tenax TA, Ambersorb XE-340) and trapped compounds were thermally desorbed into the helium stream of a gas chromatograph/mass spectrometer (GC/MS) analytical system. Total quantities of volatile organic compounds (TVOCs) were measured using a flame ionization detector (FID). Individual compounds were analyzed by a GC/MS. For the identification of compounds in the main stream GC effluent, both the specific GC retention and mass spectra were used. For the purposes of this study, the specific retention was defined based on two primary reference compounds, benzene and p-dichlorobenzene, and several secondary reference compounds. About 50 selected SICs were routinely extracted from a total ion chromatogram (TIC) to detect and quantify compounds. For each compound, a single representative ion was selected. The specific retention was calculated from the elution time on the SIC. For quantification, ion counts under a peak in the SIC were measured. The single-ion MS response factor for some of the compounds was experimentally determined using a dynamic reference procedure. For compounds whose response factors have not been measured, the total ion counts were calculated from the single ion counts by a regression equation and the total ion counts of a peak were assumed to be proportional to the concentration of the compound in the air.
A New Approach to Evaluating Pre-analysis Holding Times for the Determination of Volatile Organic Compounds in Soil
Authors: Hewitt AD
Published: March 2009

In the absence of volatilization losses, the short-term concentration stabilities of benzene, toluene, trans-1,2-dichloroethylene, and trichloroethylene were assessed in soil subsamples. Previous holding time studies for this matrix failed to eliminate volatilization as a variable, making them difficult to interpret. Here, vapor-fortified soil subsamples held in sealed glass ampoules for 14 days at 22°C experienced appreciable reductions in benzene and toluene concentrations, presumably attributable to biodegradation. When the same fortified soil was held as a subsample for either headspace or purge-and-trap analyses, it showed an appreciable reduction in toluene and a complete loss of benzene over a 14-day holding period at 4°C. In contrast, fortified soils held in sealed glass ampoules at 4°C, or dispersed in methanol and held at 22°C, showed no significant analyte losses over periods of 20 and 98 days, respectively.
Experiences with a New Soil Gas Technique for Detecting Petroleum Pollution
Authors: Mazac O , Landa I , Rohde JR , Kelly WE , Blaha JH
Published: March 2009

This paper presents field experiences obtained with a new technology for detecting petroleum pollution in soil and ground water based on “in situ” determination of hydrocarbon concentrations in soil air. Ecoprobe is a new soil gas device from RS-Dynamics in the Czech Republic. The rugged waterproof device is equipped with a built-in computer controlled semiconductor sensor. Three case histories are presented that demonstrate the use of the equipment under typical conditions. Two case histories present the use of the device under typical field conditions; the third case history compares results from the Ecoprobe and a commercial photoionization detector (PID) device.
Determination of Volatile Organic Compound Permeation Through Geomembranes
Authors: Park JK , Sakti JP , Hoopes JA
Published: March 2009

Synthetic geomembranes are commonly used as barriers or covers in hazardous waste management facilities. A confined double-compartment method (CDCM) was developed to evaluate the sorption and diffusion mechanisms of volatile organic compounds (VOCs) through high-density polyethylene (HDPE), very low-density polyethylene (VLDPE), and polyvinyl chloride (PVC) geomembranes. The loss of VOCs during testing was measured and its effect on mass transport parameters assessed. The capacity of geomembranes to adsorb VOCs, indicated by weight gain, was large, ranging from 21% to 52% of the initial geomembrane weight. In general, the total amount of VOCs lost decreased as the aqueous concentration decreased and increased as the test duration increased. The VOC loss in the CDCM test was within the maximum gas Chromatograph analytical error of about 3% to 4%; thus, the CDCM enables sorption onto and diffusion through a geomembrane to be evaluated accurately along with the influence of concentrations above and below the geomembrane on the transport behavior.
Dual-Phase Vacuum Extraction Technology for Soil and Ground-Water Remediation: A Case Study
Authors: O'Melia BC , Parson DR
Published: March 2009

Soil vapor extraction (SVE) has become a common, effective method to remediate soils contaminated by volatile organic compounds (VOCs). The technology induces a soil gas flow through the vadose zone, which extracts VOCs into the soil gas being extracted. The Dual-Phase Vacuum Extraction (DVE) system uses a high vacuum source to extract both soil gas and ground water from the same extraction well. The creation of a two-phase flow in the extraction piping eliminates the need for a separate pumping system for ground-water recovery. The high vacuum can also induce a higher recovery of ground water than typical downhole pumping methods can provide.

An Air Force Base (AFB) site, located in the United States, previously used an underground storage tank to contain waste solvents, primarily methylene chloride and perchloroethylene, from paint stripping and application operations prior to disposal. Leakage from the tank system resulted in subsurface soils and ground water with elevated levels of these chlorinated solvents. The soils at the site consist of silty clays and clayey silts with low permeabilities. The DVE system was pilot-tested to evaluate performances for site remediation.

Two extraction wells were tested separately. The average soil gas extraction rate per well was 1.05 m3 per minute with radius of influence of 10.7 m. For ground water, the average recovery rate per well was 3 L/min with a radius of influence of 23.2 m. These radii influences were significantly higher than those estimated for traditional soil vapor extraction or ground-water removal technologies. Removal rates ranged from 11.4 kg/day for an area with high levels of VOCs to 2.3 kg/day for an area with lower levels of VOCs.
Testing Decisions of The TSCA Interagency Testing Committee for Chemicals on The Canadian Environmental Protection Act Domestic Substances List and Priority Substances List: Di-tert-butylphenol, Ethyl Benzene, Brominated Flame Retardants, Phthalate Esters, Chloroparaffins, Chlorinated Benzenes, and Anilines
Authors: Walker JD
Published: March 2009

In 1976, under section 4(e) of the Toxic Substances Control Act (TSCA), the U.S. Congress created the TSCA Interagency Testing Committee (ITC) to decide which chemicals should be recommended to the Administrator of the U.S. Environmental Protection Agency for testing. In 1988, under the Canadian Environmental Protection Act (CEPA), the Government of Canada created the Domestic Substances List and Priority Substances List. This paper briefly describes the ITC, the different ITC testing decisions and a few of the ITC's 11,150 testing decisions for the 21,413 chemicals on the CEPA Domestic Substances List and some of the 24 testing decisions for the 44 chemicals and chemical groups on the CEPA Priority Substances List. The paper describes the approaches and rationales that the ITC used to make testing decisions for these chemicals on the CEPA Domestic Substances List or the CEPA Priority Substances List so that Canadians and others who need to prioritize chemicals for testing or risk reduction may apply or modify the principles used by the ITC. Also described, for the first time, for chemicals on the CEPA Domestic Substances List or the CEPA Priority Substances List, are some of the chemical fate and aquatic toxicity data that were developed during and as a result of ITC's decisions, e.g., the aquatic toxicity and chemical fate data for di-tert-butylphenol, ethyl benzene, brominated flame retardants, phthalate esters, chloroparaffins, chlorinated benzenes and anilines.
Coastal Oceanographic Characteristics and Their Impact on Marine Effluent Biotoxicity Studies During The SEFLOE II Project
Authors: Commons DN , Proni JR , Fergen RE
Published: March 2009

The Southeast Florida Outfall Experiment II (SEFLOE II) study was conducted at four ocean outfalls to determine the dispersion characteristics and biotoxicity of their effluent in the coastal ocean. The effluent from these facilities is secondary treated municipal wastewater. This paper deals with the impact of coastal oceanographic characteristics upon the biotoxicity aspect of the SEFLOE II study on data collected at the Broward County outfall.

During the study, whole effluent toxicity (WET) bioassays were compared to bioassays analyzed on samples taken from the outfall dispersion plumes. The ocean bioassays results were then evaluated along with contemporaneous current direction and speed data to determine initial and farfield dilutions and calculate Eularian and Lagrangian exposure impacts.

The bioassay comparison appears to indicate that standard WET methodology does not adequately take into consideration the substantial differences in dilution ratios and exposure times used in laboratory analyses with those experienced in actual environmental field conditions especially for ocean outfalls.
Hepatic Cytochrome P450 1A as a Biomarker for Hydrocarbon and Oxidant Pollutants in Fish: Relevance of Identification of Specific Mechanism(s) of Induction and Potential Effects on Homeostasis
Authors: Zacharewski TR , McCallum GP , Stegeman JJ , Bend JR
Published: March 2009

The induction of hepatic and extrahepatic P450 1A isozymes in fish and mammals is used as a biomarker for certain classes of toxic environmental pollutants, including polycyclic aromatic hydrocarbons (PAHs), planar polychlorinated (PCBs) and polybrominated (PBBs) biphenyl congeners, polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs). However, recent data from our laboratory have shown that rat pulmonary P450 1A1 can also be induced by arsenite or liver transplantation (via a stress mechanism), raising the possibility that regulation of this biomarker can occur by mechanisms other than Ah receptor-mediated increases of CYP1A gene transcription. To test this possibility a chimeric Ah receptor:estrogen receptor (AhRER) construct was prepared which was co-transfected with an estrogen response element-regulated luciferase reporter gene. Therefore, induction of luciferase activity demonstrates the presence of Ah receptor agonists in complex mixtures of environmental pollutants, and can be used to differentiate induction by receptor ligands and other mechanisms including oxidant stress/cytokine release. We also found that hepatic microsomes from two marine fish species and a marine mammal oxidize arachidonic acid (AA) to products which can function as potent intercellular and/or intracellular messengers, and that exposure to inducers of CYP1A significantly alters the AA metabolic profile. In concert, these observations raise the possibility that induction of P450 1A might interfere with homeostasis, particularly under conditions where significant amounts of free AA are released, as in oxidant stress.
New Developments of the Elymat Technique
Authors: Eichinger P
Published: March 2009

Injection level analysis of bulk recombination lifetime in silicon wafers with the ELYMAT technique has become possible through the development of high-stability semiconductor laser diode modules with digitally tunable optical output power. This allows for the identification of the chemical nature of dominant recombination centers such as iron and other dissolved metals, and oxygen precipitates. Metal silicide precipitates in the surface layer are quantitatively related to the surface recombination velocity which can be obtained using two lasers with distinctly different absorption depths in silicon (two-color technique).
Non-Contact Measurements of the Minority Carrier Recombination Lifetime at the Silicon Surface
Authors: Kamieniecki E
Published: March 2009

Minority carrier recombination lifetime is one of the basic parameters that can provide information regarding the condition of the silicon substrate at various stages of the device manufacturing process. The key challenge is to effectively separate surface region effects from the bulk and to determine the minority carrier lifetime that is selectively related to the surface region of the silicon. This paper reviews requirements, physical principles, and implementation of the non-contact measurement of the minority carrier recombination lifetime, which is controlled solely by the characteristics of the silicon surface and sub-surface region. The method is based on a short wavelength, low light intensity, and high modulation frequency ac-SPV. Examples of experimental results using a commercial system developed to implement such methodology are discussed.
Non-Contact Silicon Epilayer and Subsurface Characterization with UV/mm Wave Technique
Authors: Ogita Y-I , Tate N , Masumura H , Miyazaki M , Yakushiji K
Published: March 2009

Carrier lifetimes and interface recombination velocities in p/p+ and n/n+ Si epitaxial wafers are determined from the photoconductivity decays (PCDs) measured using UV/mm-wave technique. Mo and Fe are found in p/p+ Si epitaxial wafers. Gate oxide integrity (GOI) is not dependent on roughness of Rrms (root-mean-square surface roughness) 0.097–0.247 nm but dependent on subsurface damage induced by chemical mechanical polishing (CMP). Photoconductivity amplitude (PCA) signal measured by the UV/mm-wave technique correlates closely the gate oxide integrity yield. CMP induced by subsurface damage is removed by SC1 cleaning and the procedure is monitored by the UV/mm-wave technique. Lifetimes in a denuded zone (DZ) and intrinsic gettering (IG) layer are determined from the PCA signal measured using the UV/mm-wave technique.
Problems and Possibilities of Comparing Different Lifetime Measuring Instruments and Techniques
Authors: Pavelka T
Published: March 2009

The scope of the present paper is the understanding of the most important parameters influencing carrier lifetime measurement results. The role of surface conditions and carrier injection levels are discussed in details. Two techniques, μ-PCD and SPV, are compared for the case of some important recombination centers, such as Fe, Cr, Au and Co. Fe and Cr are investigated by both techniques in their single atomic form and also when pairing with dopant boron. It is shown that SPV results are in agreement with the expectations from μ-PCD data when the difference in injection level is taken into account. The capabilities of the two techniques are demonstrated in the case of Fe-B and Cr-B pair dissociation and association processes.
The Application of Minority Carrier Lifetime Techniques in Modern CZ Silicon
Authors: Falster R , Borionetti G
Published: March 2009

The applications of minority carrier recombination lifetime measurement techniques to a variety of problems associated with the manufacture and use of modern CZ silicon are discussed. The uses of the ELYMAT and microwave photoconductive decay techniques applied to issues of transition metal contamination, ultra long carrier lifetimes, oxygen clustering and precipitation, intrinsic point defect reactions and gettering phenomena are considered. The uses and limitations of injection level control and surface recombination velocity measurement are also discussed.
Spatial Nonuniformities in the Minority-Carrier Diffusion Length/Lifetime: Measurement and Implications on a Large-Area Device Performance
Authors: Sopori BL , Chen W , Symko M
Published: March 2009

Measurement of the minority-carrier diffusion length (L) or lifetime (τ) in a nonuniform material, such as a photovoltaic (PV) silicon substrate, can pose major challenges. In general, a measured value is meaningful only if the size of the probe beam ≫ L, and the material is uniform in and around the region of measurement. When the measurement conditions differ from these, there is a net flow of generated carriers from the illuminated region into the unilluminated region, and/or an exchange of carriers within the neighboring regions. In these cases, the error can arise from two mechanisms: (i) recombination at the surface, and (ii) exchange of carriers within regions of different diffusion lengths. These errors can be minimized by the proper selection of the carrier generation conditions and sample preparation. By combining the experimental results with less rigorous theoretical analyses, the conditions for the measurement of local values of L (or τ) in a PV substrate can be determined. A network model can be used to integrate the influence of spatial distribution of L-values on a nonuniform substrate and predict the electrical characteristics of the large-area device fabricated on it.
Uranium Isotope Measurements by Quadrupole ICP-MS for Process Monitoring of Enrichment
Authors: Policke TA , Bolin RN , Harris TL
Published: March 2009

Historically, uranium isotopic ratio measurements in the nuclear industry have been performed using Thermal Ionization Mass Spectrometry (TIMS); primarily due to the high level of precision that can be achieved. TIMS analysis, however, requires sample purification and intricate sample loading. Quadrupole (low resolution, single detector) inductively coupled plasma — mass spectrometry, Q-ICP-MS, overcomes these disadvantages and is a cost-effective alternative, i.e., in terms of initial capital, maintenance, and operating costs. This paper presents a simple, single standard approach for measuring uranium isotope content in various solid and liquid nuclear materials along with some comparison data of Q-ICP-MS and TIMS. Intensity ratios of 234U, 235U, 236U, and 238U to total U intensity are produced, providing the enrichment level or percent 235U. A detailed description of the instrument and data collection parameters is also provided. Optimal precision and accuracy are achieved through the use of a single standard which is closely matched to the enrichment and concentration of the samples. Depending upon the standard chosen, enrichments between depleted and 97% can be quantified. Standard deviations for the major uranium isotopes are typically within 0.02 absolute and at least an order of magnitude lower for the minor U isotope abundances.
Actinide, Elemental, and Fission Product Measurements by ICPMS at the Savannah River Site
Authors: Tovo1 LL , Clymire JW , Boyce WT , Kinard WF
Published: March 2009

A VG Elemental Inductively coupled plasma-mass spectrometer (ICPMS), PlasmaQuad 1 (PQ1) Model No. 4, installed in a radiological controlled hood, is used by the Savannah River Technology Center to provide non-routine mass measurements for environmental monitoring, waste tank characterization studies, isotope ratios for criticality determinations, and the measurement of elemental, fission product, and actinide mass distributions of the glass product from the Defense Waste Processing Facility (DWPF).

Modifications to improve instrument reliability, sample preparation, and data handling, as well as modifications to the laboratory that permit measurements in a radioactive environment, will be discussed. Based on our operating experience, two laboratory facilities are being prepared for additional instruments to operate in a radioactive environment. A separate instrument is being installed for non-radioactive measurements and method development.
Evaluation of Nebulizer Performance within the ICP-MS Measurement System for Analysis of SRS Radiological Waste Tank Simulated Solutions
Authors: Jones VD
Published: March 2009

High level radioactive waste tanks at the Savannah River Site are high in salt content. The average Total Dissolved Solids (TDS) content is approximately 25%. For ICP-MS optimum signal stability and to reduce blockage of nebulizers and sampling orifices, it is usual to limit analyte solutions to a TDS content of nominally < 0.2%. Dilution to this level to reduce the matrix effect may push some analytes of interest below detectable levels. Five commercially available nebulizers were evaluated in a field study as part of the ICP-MS measurement system for their performance in a high salt matrix. The nebulizers surveyed were a meinhard concentric, cross-flow, micro-concentric (MCN), V-groove, and a direct injection nebulizer (DIN). Analytes spiked into non-radioactive diluted salt solutions ranging from nominal 0.25 – 1.0% TDS were repetitively analyzed with the goal of determining stability of response signal and magnitude of any signal loss/suppression resulting from the diluted salt matrix. The cross-flow nebulizer provided the most stable signal for all salt matrices with the smallest signal loss/suppression due to this matrix. The DIN exhibited a serious lack of tolerance for TDS; possibly due to physical de-tuning of the nebulizer efficiency.
Determination of Technetium-99, Neptunium-237 and Isotopes of Thorium in Uranyl Nitrate Solutions From a Reprocessing Plant, Using Double-Focusing ICP-MS
Authors: Mitterrand B , Leprovost P , Delaunay J , Vian AM
Published: March 2009

The determination of some radionuclides in uranyl nitrate solutions from a reprocessing plant through chemical or radiochemical methods may be tedious, with poor precision. Quadrupole ICP-MS and, more recently, double-focusing ICP-MS, with high resolution capabilities, have proved to be very efficient tools for such determinations. These improvements will be illustrated by the examples of Technetium-99, Neptunium-237 and Thorium.
Evaluation of Chelation Preconcentration for the Determination of Actinide Elements by Flow Injection ICP-MS
Authors: Evans EH , Truscott JB , Bromley L , Jones P , Turner J , Fairman BE
Published: March 2009

A chelation column preconcentration method has been developed for the determination of uranium and thorium in waters by ICP-MS. Detection limits of 24 pg and 60 pg respectively were obtained, but these were blank limited. Uranium and Thorium were determined in certified reference materials. Results for uranium were 121 ± 21 and 15 ± 3 ng g-1 in NIST 1566a and NIST 1575 compared with certified values of 132 ± 12 and 20 ± 4 ng g-1 respectively. Results for thorium were 29 ± 8 and 28 ± 5 ng g-1 in NIST 1566a and NIST 1575 compared with indicative and certified values of 40 and 37 ± 3 ng g-1 respectively. The on-line separation of actinide radionuclides was achieved by selective elution of U, Th, Pu, Np, and Am.
Determination of Uranium in Clinical and Environmental Samples by FIAS-ICPMS
Authors: Karpas Z , Lorber A , Halicz L , Gavrieli I
Published: March 2009

Uranium may enter the human body through ingestion or inhalation. Ingestion of uranium compounds through the diet, mainly drinking water, is a common occurrence, as these compounds are present in the biosphere. Inhalation of uranium-containing particles is mainly an occupational safety problem, but may also take place in areas where uranium compounds are abundant. The uranium concentration in urine samples may serve as an indication of the total uranium body content. A method based on flow injection and inductively coupled plasma mass spectrometry (FIAS-ICPMS) was found to be most suitable for determination of uranium in clinical samples (urine and serum), environmental samples (seawater, wells and carbonate rocks) and in liquids consumed by humans (drinking water and commercial beverages). Some examples of the application of the FIAS-ICPMS method are reviewed and presented here.
Determination of Radionuclides in Biological Fluids Using a High Resolution ICP-MS in Low Resolution Mode
Authors: Pickford CJ , Haines J , Heam R , McAughey J
Published: March 2009

High Resolution (HR) ICP-MS in low resolution mode was used with ultrasonic nebulization to determine long-lived radionuclides and surrogates in human body fluid samples. Although very sensitive, achieving LODs less than 0.1 fg/mL for 244Pu, a number of molecular ion interferences have been encountered from commonly-occurring species which limit sensitivity and require the development of specialized sample preparation routes.
Use of a Two-Body Belt Abrasion Test to Measure the Grindability of Advanced Ceramic Materials
Authors: Blau PJ , Zanoria ES
Published: March 2009

The same properties that make engineering materials attractive for use on severe thermal and mechanical environments (e.g., high hardness, high temperature strength, high fracture toughness) generally tend to make those materials difficult to grind and finish. In the mid-1990's, a belt abrasion test was developed under subcontract to Oak Ridge National Laboratory to help to assess the grindability of structural ceramic materials. The procedure involves applying a 10 N normal force to the end face of a 3 × 4 mm cross-section test bar for 30 seconds which is rubbed against a wet, 220 grit diamond belt moving at 10 m/s. By measuring the change in the bar length after at least six 30-second tests, a belt grindability index is computed and expressed using the same units as a traditional wear factor (i.e., mm3/N-m). The test has shown an excellent capability to discriminate not only between ceramics of different basic compositions, e.g. Al2O3, SiC, and Si3N4, but also between different lots of the same basic ceramic. Test-to-test variability decreases if the belt is worn in on the material of interest. The surface roughness of the abraded ends of the test specimens does not correlate directly with the belt grindability index, but instead reflects another attribute of grindability; namely, the ability of a material to abrade smoothly without leaving excessive rough and pitted areas.
Observations on the Grinding of Alumina with Variations in Belt Speed, Load, Sample Rotation, and Grinding Fluids
Authors: Schwartz CJ , Bahadur S
Published: March 2009

The volume of material removed in the grinding of alumina on a diamond-impregnated grinding belt was studied. Four grinding process parameters were tested: belt speed, normal load at the pin's contact surface, sample rotation during grinding, and grinding fluid. The results showed that at low loads the belt speed did not have a significant effect on material removal rates; however, the material removal rate decreased at higher loads combined with higher speeds. It decreased, in particular, when the sample was also rotated. Of the fluids used, the 50% ethylene glycol - 50% water mixture produced the highest material removal rates while the lowest were produced by biodegradable soybean oil. The test conditions that produced high temperatures at the contact surface contributed to plowing as opposed to cutting and resulted in reduced material removal rates. The reasons for these variations were investigated by scanning electron microscopy of the surfaces, which revealed evidence of plastic deformation and temperature rise during grinding.
Reducing Tool Wear When Machining Austenitic Stainless Steels
Authors: Magee JH , Kosa T
Published: March 2009

Austenitic stainless steels are considered more difficult to machine than carbon steels due to their high work hardening rate, large spread between yield and ultimate tensile strength, high toughness and ductility, and low thermal conductivity. These characteristics can result in a built-up edge or excessive tool wear during machining, especially when the cutting speed is too high. The practical solution is to lower the cutting speed until tool life reaches an acceptable level. However, lower machining speed negatively impacts productivity. Thus, in order to overcome tool wear at relatively high machining speeds for these alloys, on-going research is being performed to improve cutting fluids, develop more wear-resistant tools, and to modify stainless steels to make them less likely to cause tool wear.

This paper discusses compositional modifications to the two most commonly machined austenitic stainless steels (Type 303 and 304) which reduced their susceptibility to tool wear, and allowed these grades to be machined at higher cutting speeds.
Turning of High Strength Steel Alloy with PVD- and CVD-Coated Inserts
Authors: Jawaid A , Olajire KA
Published: March 2009

PVD TiN-coated(T1) and CVD Ti(C,N)/TiC/Al2O3-coated(T2) inserts were used to machine a high strength low-alloy(HSLA) steel to assess their performance. The single-layer PVD-coated insert gave comparable tool life results to the triple-layer CVD-coated insert due to better coating adhesion, finer grain size and lower cobalt content. Observed active failure modes at high cutting speeds and feed rate were mainly chipping/fracture on the minor cutting edge for T1 and excessive nose wear for T2. The wear mechanisms on the former were interfacial sliding, dissolution/diffusion, and attrition wear mechanisms, while the latter wore principally by interfacial sliding and plastic deformation.
Characterization of the Wear Processes due to the Material Erosion Mechanisms
Authors: Chincholle LH
Published: March 2009

A device to measure the instantaneous erosion rate has been perfected. It is available for all types of erosion such as those involving corrosion, abrasion, erosion by shock and cavitation. The calibration being made, it gives a quantitative value of the erosion and moreover, on certain cases, it is possible to deduce the erosion type. A wide range of applications is possible for using this device. This paper presents some experiments carried out in the wear domain. The first results obtained in a specific conditions for the fretting erosion are interesting. It can be seen that the evolution of the instantaneous erosion behavior varies with some parameters such as the applied force, frequency, friction coefficient and time. By way of a better knowledge of the oxide formation, this new tool gives new insights to help analyze the complicated instantaneous processes of wear, by means of current density measurement.
Analysis of the Second ASTM Round-Robin Program on Opening-Load Measurement Using the Adjusted Compliance Ratio Technique
Authors: Donald JK , Phillips EP
Published: March 2009

The results of the Second Round-Robin on Opening-Load Measurement established the basis for a recent addition to ASTM E 647—“Recommended Practice for Determination of Fatigue Crack Opening Load from Compliance.” The technique involves characterizing the deviation in linearity of a load-displacement curve and reporting, as a minimum, the opening load corresponding to a 2% slope offset. The opening load and associated ΔKeff values reported showed significant scatter although this scatter was reduced when the data were subjected to a rigorous accept/reject criterion. Refinements in the method of handling data with high “noise” have further reduced scatter compared with the original analysis. Since each participant provided digitized load-displacement curves, the data from 17 test samples (10 participants) were reanalyzed using the “adjusted compliance ratio” (ACR) technique to evaluate ΔKeff. A comparison between the two methods shows that the ACR technique gives a higher mean value of ΔKeff than does the ASTM procedure. The ACR technique also shows a stronger correlation with crack growth rate data than does the ASTM procedure, with a slope comparable to that of a typical fatigue crack growth rate test. However, the mean value of ΔKeff based on the ASTM procedure shows better agreement with high stress ratio “closure free” data than does the ACR technique. This seemingly contradictory result can be partially explained in terms of second-order effects not normally considered significant.
Evaluation of the Adjusted Compliance Ratio Technique for Measuring Crack Closure in Ti-6A1-4V
Authors: Graham SM , Tregoning R , Zhang XJ
Published: March 2009

Standard fatigue crack growth rate tests within the upper threshold and Paris Law regions were conducted on specimens from three large, standard-grade Ti-6Al-4V forgings in order to evaluate the adjusted compliance ratio (ACR) method for closure correction. Constant R-ratio tests were conducted to generate data containing crack-tip closure, and constant Kmax tests were performed to produce high R ratio, and hence closure-free, data in the threshold and upper threshold regimes. Direct comparisons are made of the closure corrected data generated using the current ASTM slope offset method and the ACR method. While it is clear that the ACR technique is easier to implement and will always lead to less closure correction than the slope offset technique, it is not clear which is more accurate. It appears that the slope offset method may be overcorrecting for closure effects and the ACR method may be undercorrecting.
Experimental Determination of Crack Closure by the Cut Compliance Technique
Authors: Schindler H-J
Published: March 2009

The cut compliance method was developed to measure residual stress profiles. Its idea is to release them by introducing progressively a cut into the considered body. From the strain change due to progressive cutting it is possible to calculate the distribution of the released stresses. Since the method uses fracture mechanics principles the stress intensity factor due to residual stresses is delivered as well. Being a special type of residual stresses, the distribution of the contact stresses of fatigue crack closure and the corresponding closure stress intensity factors can be suitably determined by this method. Furthermore, it enables the residual stresses in front of the crack tip to be determined, which in crack retardation play a role as important as the closure effects. The basic theoretical relations for some frequently used fatigue specimens are analytically derived. They also can serve to evaluate the contact stresses from the commonly used unloading compliance technique, which is often used to identify crack closure effects. Some preliminary examples demonstrate the capability of the suggested method.
Measurement of Fatigue Crack Closure for Negative Stress Ratio
Authors: Romeiro FFJ , Domingos CA , de Freitas MJM
Published: March 2009

The concept of fatigue crack closure, introduced in the 60's by Elber, has been used to explain a wide range of positive stress ratio crack propagation results (R ⩾ 0). Less attention has been given to fatigue loading for negative stress ratios (R < 0). In this work the results of crack propagation tests of middle-crack tension M(T) specimens of a normalized medium carbon steel DIN Ck 45 for a wide range of stress ratios from 0.7 ⩾ R ⩾ -3 are presented. Crack closure loads were measured with the compliance technique at test frequency, using a data acquisition system. Negative crack closure loads were found for negative stress ratios R ⩽ -1, which can explain higher crack propagation rates and accelerations in crack growth during variable-amplitude tests where compressive loads of different stress ratios are present.
A Comparison of Two Total Fatigue Life Prediction Methods
Authors: Chen N , Lawrence FV
Published: March 2009

A 2-D analytical model which is termed the PICC-RICC model combines the effects of plasticity-induced crack closure (PICC) and roughness-induced crack closure (RICC). The PICC-RICC model handles naturally the gradual transition from RICC to PICC dominated crack growth. In this study, the PICC-RICC model is combined with a crack nucleation model to predict the total fatigue life of a notched component. This modified PICC-RICC model will be used to examine several controversial aspects of an earlier, computationally simpler total-life model known as the IP model.
Contact of Nonflat Crack Surfaces During Fatigue
Authors: Sehitoglu H , Garcia AM
Published: March 2009

A model has been developed to predict crack opening and closure behavior for propagating fatigue cracks which are nonflat and undergo significant sliding displacements. Crack surfaces were characterized by a random distribution of asperity heights, density of asperities, and asperity radii. The propagating crack was subdivided into ligaments and each ligament was treated as a contact problem between two randomly rough surfaces. The far-field tensile stresses were varied in a cyclic manner for R = 0.1 and -1 loading conditions. The contact stresses at the minimal load were determined by analyzing the local crushing of the asperities. Then, upon loading the crack opening, stresses were computed when the contact stresses were overcome. The results of crack opening stresses were correlated with CTOD/σ0 where CTOD is the crack-tip opening displacement and σ0 is the average asperity height. The asperity effects on closure were compared with plasticity-induced closure results from the literature for identification of conditions when one mechanism dominates the other.
Use of Acoustic Emission to Characterize Focal and Diffuse Microdamage in Bone
Authors: Rajachar RM , Chow DL , Curtis CE , Weissman NA , Kohn DH
Published: March 2009

Fatigue of cortical bone results in the initiation, accumulation, and propagation of microdamage. AE techniques were adopted to monitor damage generated during ex-vivo tension-tension fatigue testing of cortical bone. The primary objectives were to determine the sensitivity of AE in detecting microdamage in cortical bone and to elucidate mechanisms guiding the onset of microdamage. Fatigue cycle data and histological data show that AE techniques are more sensitive than modulus reduction techniques in detecting incipient damage in cortical bone. Confocal microscopy revealed the ability of AE to detect crack lengths and damage zone dimensions as small as 25 μm. Furthermore, measured signal parameters such as AE events, event amplitude, duration, and energy suggest that AE techniques can detect and distinguish microdamage mechanisms spatially and temporally in bone. As fatigue processes continue, AE increases in terms of number of events, event intensities and spatial distribution. Diffuse damage appears to be a precursor to the development of linear microcracks. The spatial and temporal sequence of AE events enables differentiation between linear microcracks and more diffuse damage.
On the Necessity of a New Standard for the Acoustic Emission Characterization of Concrete and Reinforced Concrete Structures
Authors: Nesvijski EG
Published: March 2009

The acoustic emission (AE) method, though rather difficult in application and interpretation of results, has a great potential for characterization of stress, bearing properties, fatigue, and fracture of materials. The existing NDT standards that employ AE cover only a limited number of materials and structures. Direct compilation of these standards for materials with distinctive properties is difficult and sometimes impossible. for instance, concrete is a “living” material and AE can be registered immediately after preparation of cement or concrete mix, then during setting, and later during curing. AE in hard concrete can be registered due to initiation and growth of cracks under different kinds of physical factors. Classification of the signatures for different stages of concrete life and service is given. Some new models of the quantitative AE analysis are presented in this work.
Analysis of Fracture Scale and Material Quality Monitoring with the Help of Acoustic Emission Measurements
Authors: Nikulin SA , Shtremel MA , Khanzhin VG , Kurianova EY , Markelov AP
Published: March 2009

The results of a study of the mechanism and kinetics of metallic material fracture (dual phase steels, binary Zr-2,5Nb and multicomponental Zr-1,2Sn-1Nb-0,3Fe alloys, reinforced surface layers and protective coatings, multifilamentary Nb3Sn and Nb-Ti based superconductors and HTSC-based composition wires) are given. The quantity fracture analysis is based on measurements of acoustic impulse peak (maximum) amplitudes by non-resonance sensors for linear measurement of acoustic shifts and crack parameters measurement. The developed methods of absolute calibration of AE equipment were checked by testing various types of materials and crack parameter measurements in laps and fractures. The calibration dependencies for quantity measurements are shown. The possibilities of AE for quality analysis and for characterizing of materials in the process of various mechanical tests and in the process of pressure processing with the help of a developed experimental computerized AE system are demonstrated.
Screening Approaches for the Evaluation of Endocrine Disruption in Invertebrates
Authors: LeBlanc GA
Published: March 2009

Chemical toxicity to endocrine processes is recognized as a means by which exposure to low, environmentally-relevant levels of chemicals may result in profound effects at both the organism and population level. Accordingly, toxicologists are faced with the daunting task of developing effective screening tools for the detection of endocrine related toxicity. Invertebrates utilize endocrine processes not found in the vertebrates and thus must be included in such screening processes. Standard toxicity test methods such as the 21-day daphnid and the 28-day mysid reproductive assays can be utilized to evaluate endocrine-related toxicity with the inclusion of appropriate endpoints. Endpoints would encompass neonatal development, growth, maturation, and reproduction (both sexual and asexual). Various anatomical/physiological endpoints are described for daphnids that can be incorporated into standard test protocols for other invertebrates as well. In addition, molecular/biochemical endpoints are described that would provide insight into the mechanisms responsible for the observed toxicity. Such mechanistic information could then be used to identify potentially susceptible groups of invertebrates that should be included in subsequent definitive toxicity characterizations.
Hormonal Processes in Decapod Crustacean Larvae as Biomarkers of Endocrine Disrupting Chemicals in the Marine Environment
Authors: McKenney CL
Published: March 2009

Knowledge of endocrine control of the complex larval developmental processes in insects (metamorphosis) has led to the introduction of insect hormones and their analogues as insecticides known as insect growth regulators (IGRs) with the largest group being juvenile hormone analogues (JHAs). Developmental and metabolic alterations in estuarine crustacean larvae induced by JHAs suggest that these compounds may be interfering with an endocrine system using JH-like compounds. These responses of crustacean larvae during the metamorphic process can be used in the development of biomarkers for the environmental impact of these types of compounds and other potential endocrine disrupting chemicals on estuarine biota.
Methods to Assess the Effects of Environmental Chemicals on the Brain-Pituitary-Gonad Axis of the Reproductive System
Authors: Magliulo-Cepriano L , Schreibman MP
Published: March 2009

In all vertebrates, the neuroendocrine system serves as the primary and essential link between the external and internal environments and a multitude of physiological systems, including the reproductive system. In response to changes in the environment and fluctuations in levels of circulating humoral agents, the neuroendocrine system is able to reverse, maintain or advance physiological events. Endocrine disrupting compounds are believed to wreak havoc on reproduction and development by interfering in the normal flow of information along the brain-pituitary-gonad axis. While the final effects of these compounds may be easily determined in a number of species, utilization of non-traditional research animals, such as some fishes in which the pattern of information flow along the brain-pituitary-gonad axis has been meticulously detailed and documented, will provide excellent and novel means of elucidating not only the final effects but the cytological, histological and systemic mechanisms of action of these endocrine disruptors. This report presents methods of assessing the effects of endocrine disrupting compounds on a variety of physiological and morphological parameters in fishes.
Localization and Sex Steroid Regulation of Brain Aromatase Activity: Identification of a Positive Feedback Mechanism that may be Triggered by Environmental Cues
Authors: Melo AC , Edmunds JSG , Ramsdell JS
Published: March 2009

We performed assays for aromatase activity in serial 200 μm sections of the three orthogonal planes of the brain and produced a three dimensional reconstruction of aromatase levels in Medaka (Oryzias latipes) brain. The regulation of this brain aromatase activity by sex steroids was then examined by in vivo exposure bioassays. We demonstrate that the activity of brain aromatase is localized to an area that contains the hypothalamus, a region of the brain involved in the regulation of the reproductive function. The exposure of Medaka to estradiol lead to increased brain aromatase levels; whereas, exposure to methyl-testosterone lead to decreased brain aromatase levels. The regulation of brain aromatase levels by both product and substrate may provide a sensitive trigger for environmental cues to alter sex behavior.
Pesticide Effects on Prolactin Release from the Rostral Pars Distalis In Vitro and Their Effects on Growth In Vivo in the Tilapia (Oreochromis mossambicus)
Authors: Meredith HO , Richman NH , Collier JT , Seale AP , Riley LG , Ball CH , Shimoda SK , Stetson MH , Grau EG
Published: March 2009

Prolactin release from prolactin-cell-containing tissue, the rostral pars distalis (RPD) of the tilapia pituitary, is sensitive to estrogens. This study was undertaken to evaluate the effect of two estrogenic pesticides, p,p'-DDT and o,p'-DDD, on the release of both tilapia prolactins (PRL177 and PRL188) from the RPD in static incubation, and to examine the effect of exposing tilapia fry to o,p' -DDD on growth and development. We found thatp,p' -DDT stimulated the release of both PRL177 and PRL188, and that o,p'-DDD inhibited the release of PRL188 at the concentrations employed. We also found that 8 months after exposing fry to o,p'-DDD for 28 days, the body weight and liver weight of males and females were significantly different from those of untreated control animals (P<0.01). Gonad weight and pituitary weight were not affected. We also found that 8 months after exposing fry to the estrogen ethynylestradiol (EE2), the body weight of males was significantly lower (P<0.01) and the body weight of females was significantly higher (P<0.01) than that of the respective untreated controls. Treatment with EE2 also significantly lowered (P<0.05) the liver weight of males and significantly increased (P<0.01) the gonad and pituitary weights of females compared with their respective controls. The lowest dose of o,p' -DDD used in the in vivo study induced a significant increase in the number of males, an effect opposite to that of EE2.
Endocrine Disruption, Organochlorine Pesticides, and Human Development: An Overview
Authors: Adeshina F , Kueberuwa SS
Published: March 2009

The current scientific knowledge suggests that numerous anthropogenic substances in the environment potentially disrupt the endocrine system in humans, thereby, causing severe deleterious effects. The mechanisms of action of these chemicals are presently not well understood. A model for the developmental effects of these substances is largely based on diethylstilbestrol, a potent synthetic estrogen, that is known to induce morphological and physiological changes in the reproductive tracts of both men and women. Since several organochlorine pesticides have been identified as estrogenic and/or anti-androgenic, it is imperative to reassess the existing developmental and reproductive toxicity databases of these chemicals. This paper provides a critical review of available toxicological data, and also identifies important research needs for the health risk assessment of pre- and post-natal exposures to endocrine-disrupting organochlorine pesticides.