bluuebunny/crossref_metadata_2025_split huggingface dataset:
X-Ray Fluorescence Spectrometry for Analysis of Fly Ash Column Leachates
Authors: Young HW , Boybay M , Young JC , Demirel T 
Published: March 2009

An investigation was conducted to determine the suitability of X-ray fluorescence (XRF) for analyzing the complex mixture of elements in fly ash leachates.
XRF analysis was found to provide reasonably accurate measurement with coefficients of variation ranging from 2 to 8% for most elements. Sources of error included interferences by stimulation of fluorescent emissions by strong secondary fluorescent radiation, overlap of emission peaks, and adsorption of fluorescent emission from one element by others.
Standardization required preparation of complex mixtures of elements similar in composition to that of leachates. This required considerable preparation time and effort, but once the standards were stored in instrument memory, analysis for as many as 30 elements in leachate specimens required only about 60 min. This study showed that XRF potentially is a valuable tool for analysis of the complex elemental mixtures in fly ash leachates, but additional work is needed to reduce error and increase instrument sensitivity.
Selenium: A Hazard Assessment and a Water Quality Criterion Calculation
Authors: Adams WJ , Johnson HE 
Published: March 2009

An aquatic environmental hazard assessment for inorganic selenium compounds was performed. Studies on environmental exposure concentrations, bioconcentration potential, and acute and chronic toxicity to aquatic organisms were reviewed. An average aqueous environmental exposure concentration of 1.0 μg/litre was calculated, using data from 22 lakes. The geometric means of the maximum acceptable toxicant concentrations (MATCs) for fathead minnows, rainbow trout, Daphnia magna, mysid shrimp, and sheepshead minnows were 0.22, 0.18, 0.13, 0.36, and 0.67 mg/litre, respectively. The safety factors, based on the ratio of the chronic geometric mean of the MATC to the average environmental exposure concentration, were determined to be greater than 130 for all aquatic species tested. The data suggest that existing aqueous environmental levels of selenium present little hazard to aquatic life.
The aquatic toxicity data base developed in the present study, together with previously reported information, was used to calculate a water quality criterion. The authors estimate that a concentration of 52 μg/litre, if not exceeded, should provide adequate protection for most aquatic species.
Use of Bluegill Toxicity Indexes in Illinois
Authors: Lubinski KS , Sparks RE 
Published: March 2009

Toxicity indexes that relate concentrations of up to 20 toxicants to their acute lethal effects on bluegill, Lepomis macrochirus (Rafinesque), have been compiled during three water research projects in Illinois. Indexes were compiled for individual stream stations by expressing each toxicant concentration as a fraction of its 96-h median lethal concentration (LC50) to bluegill (adjusted when possible for varying conditions of pH, temperature, dissolved oxygen, and hardness). The resulting component toxicities in bluegill toxic units (BGTUs) were added to yield a toxicity index for each station. Computer programs were developed to perform these calculations using data generated routinely by established water quality monitoring programs or by short-term spot surveys.
The objectives of the projects for which toxicity indexes were compiled included: (1) assessment of Illinois River water quality for fish life, (2) identification of the relationships between fish populations and ammonia and chlorine in sewage discharges, and (3) development of a continuous stress function to evaluate the responses of aquatic communities to environmental and pollutional factors. The projects have resulted in useful comparisons of stream toxicity values to fish numbers and diversity. Although the question of whether the acute effects of combinations of toxicants are additive may never be resolved, toxicity indexes have provided valuable comparisons of water quality at different stations, and at the same station through time, and have identified potentially dangerous toxicant problems.
Acute Toxicities of Equimolar and Equitoxic Surfactant Mixtures to Daphnia magna and Lepomis macrochirus
Authors: Lewis MA , Perry RL 
Published: March 2009

The acute toxicities of anionic, nonionic, and cationic detergent surfactants to Daphnia and bluegill were determined for individual surfactants and for binary and ternary surfactant mixtures. Data were analyzed using several models, including toxic units, the additive index, and concentration and response addition.
The effects of the single surfactants, in decreasing order of toxicity, were as follows: in Daphnia, the effects were cationic, nonionic, and anionic; in bluegill, nonionic, anionic, and cationic. Approximately 72 percent of the binary and ternary mixtures were less than additive in response to either organism when analyzed by toxic units or by the additive index. Approximately 24 percent of the mixtures demonstrated simple addition using these methods. The anionic-cationic mixtures were synergistic to bluegill and in one case to Daphnia. The toxicities of the majority of mixtures fit response and concentration additive models; conformity to the response additive model was most common. Response addition, as applied and evaluated during the present investigation, offers an approach for early estimation and prediction of the toxicities of surfactant mixtures.
New Design and Use of a Fish Metabolism Chamber
Authors: Schmidt EJ , Kimerle RA 
Published: March 2009

A 10-litre rectangular fish metabolism chamber was constructed with acrylic plastic so that it would passively restrain a 250 to 450-g fish. Gill excretion products were separated from anal excretion products by a rubber septum. Urine was collected through a catheter, and respired carbon dioxide (CO2) was collected in a gas chamber. Channel catfish (Ictalurus punctatus) were given doses of carbon-14 (14C) radiolabeled carboxymethyltartonate (CMT) and linear alkylbenzene sulfonate (LAS) by either intraperitoneal injection, liquid gavage, or food gavage. Improved techniques were developed for catheterizing fish.
Analysis of 14C activity in gill chamber water, anal chamber water, urine, and the CO2 scrubber enabled quantification of the routes and rates of chemical elimination. Essentially, 100 percent of the CMT from the intraperitoneal dose was excreted within 4 days, 85 percent in the urine with the remainder in the anal and gill chamber waters and the CO2 scrubber. A greater portion of total LAS excretion showed in the anal and gill chambers, with urine still being the most important route of elimination. The rate of chemical elimination was greatest in the urine during the first 48 h.
Defects and High-Pressure Steam Oxidation of Silicon
Authors: Katz LE 
Published: March 2009

Recently high-pressure oxidation has been successfully applied to both bipolar and metal-oxide-semiconductor (MOS) technologies. This paper reviews those aspects of high-pressure oxidation, from a perfection standpoint, which are necessary to qualify this technique for incorporation into device processing.Oxidation-induced stacking faults, which are known to degrade junctions, are shown to be reduced with high-pressure oxidation when compared with conventional wet oxidation at atmospheric pressure. Models are discussed which correlate well with this observation.Impurity levels, as measured by defect state concentration measurements and neutron activation, have values equal to or lower than those for wafers oxidized by conventional techniques. A review of oxide charges present, as observed by several authors on various equipment including commercial pyrogenic and water-injected systems, shows values comparable to one atmosphere control. Additionally, process parameters affecting stress in the growing oxide film are discussed.Overall, the high-pressure oxidation technique appears to grow high-quality oxides comparable to those grown in qualified conventional systems.
Some Salient Features of the Tearing Instability Theory
Authors: Ernst HA 
Published: March 2009

In this work the problem of the stability of a system deformed under displacement and load-controlled conditions is examined. The instability conditions are found from the load versus displacements, P-δ, characteristics of the system and the stiffness of the structure, KM, on a completely general basis. The analysis is performed for the system in series with a spring under displacement control and for the system in parallel with the spring under load-controlled conditions.
In addition it is shown that the conditions for instability found for both situations using the tearing instability theory are in complete agreement with those obtained under a completely general basis. As a result the tearing instability theory is proven to be always valid in the sense that instability will occur if and only if Tapp &gt; Tmat.
Finally, a small experimental program on a nickel-chromium-molybdenum-vanadium rotor steel was conducted in order to prove that structures can be designed to assure stable crack growth under load-controlled conditions beyond maximum load.
Ductile Crack Growth Analysis Within the Ductile-Brittle Transition Regime: Predicting the Permissible Extent of Ductile Crack Growth
Authors: Milne I , Curry DA 
Published: March 2009

The ductile-brittle transition in ferritic steels is reviewed using data from pressure vessel steels A533B, A508, BS1501-271, and their associated weld metals and heat-affected zones in a variety of conditions. A schematic model is presented which provides a rational basis for understanding the phenomenon and making predictions. This model, which is consistent with the predictions obtained from physical models of cleavage fracture, contains the following important features. 1. If in the transition regime, KIc is defined as the fracture toughness at the onset of the brittle mode of fracture and KIJ is defined as the fracture toughness at the onset of ductile crack growth, then KIc &gt; KIJ. 2. The ductile crack extension obtained between the initiation of ductile crack growth and the onset of brittle fracture is defined by the elastic-plastic crack growth resistance curve. 3. KIc cannot be reached without generating the appropriate amount of ductile crack extension.
It follows that, when performing a failure analysis in this temperature regime, the choice of KIJ as a failure criterion is unnecessarily pessimistic and inconsistant with the choice of KIc as a failure criterion below these temperatures. A procedure is presented which allows the permissible extent of crack growth to be obtained.
An Evaluation of the JR-Curve Method for Fracture Toughness Characterization
Authors: McCabe DE , Landes JD , Ernst HA 
Published: March 2009

This program involved the testing of compact specimens made from A508 Class 2A tube plate material. The objective of the program was to study specimen size and plan view dimension effects on the upper-shelf [204°C(400°F)] JR-curve toughness behavior. Low upper-shelf Charpy toughness relative to typical reactor vessel materials was preferred.
The basis material was a 330-cm-diameter (130 in.) by 61-cm-thick (24 in.) slab of tube plate that had been rejected from service after ultrasonic inspection. There was some unwanted variability in strength and toughness properties and a careful specimen sampling plan did not entirely eliminate material variability from the test matrix. Therefore, a dimensional analysis in the form of key curves was used to categorize the material before attempting to decipher specimen geometry effects on the JR-curve behavior. It was then possible to show that specimens of all sizes from 1T to 10T that had equal conditions of constraint would develop the same JR-curve. The principal limitation on small specimens was that they simply lacked sufficient ligament size to sustain crack growth for full JR-curve development.
The omega (ω) criterion was evaluated with the hope of identifying when J—Δap data from specimens with short ligaments could be expected to depart from the specimen-size-independent JR-curve. This was not successful herein from the standpoint that few specimens had sufficiently small ligaments to display this deviation. When deviation did in fact occur, it was not distinctly associated with a given value of ω.
A comparison was made between the load-displacement behavior of two 1T compact specimens having equal Charpy (CVN) toughness and JR-curves but unequal strength properties (88 RB versus 99 RB). This was possible because of uniquely variable metallurgical conditions. The high-hardness specimen showed 40 percent greater load-bearing capacity. This was a good demonstration of why more than just JR-curve behavior should be used to judge the suitability of materials for given applications. Material strength properties are contained in crack drive representations which are curves that are compared with JR-curves. From such comparisons it is possible to predict load versus displacement and crack instability in untested configurations. Hence, part of the material flow property effect is not considered when comparing just JR-curves.
J-R Curve Characterization of Irradiated Low-Shelf Nuclear Vessel Steels
Authors: Loss FJ , Menke BH , Hiser AL , Watson HE 
Published: March 2009

The J-R curve behavior of irradiated nuclear pressure vessel steels is characterized in the ductile upper-shelf regime in order to provide a materials basis with which to assess the margin of safety against fracture for water reactor vessels exhibiting a low upper-shelf CV energy. With the single specimen compliance technique, the R-curve is shown to follow a power-law behavior for small crack extension, and this phenomenon has led to a proposed new indexing procedure forJIc. In addition, a specimen size dependence of the R-curve has been suggested by the results of similar compact tension specimens up to 100 mm thick and which have sufficiently deep side grooves to produce a straight crack-front extension.
R-curve data are presented in terms of a J versus T instability diagram which couples material and structural parameters, thereby permitting an analysis to be made of the margin against failure in terms of J. Also, a correlation has been suggested between the R-curve parameters and CV shelf energy; this could enhance the structural significance of CV reactor surveillance data.
Photoacoustic Spectroscopy of Adsorbed Surface Impurities on Alkali-Halide Laser Windows
Authors: McDavid JM , Yee SS 
Published: March 2009

Significant infrared absorption can arise from vapors adsorbed on laser window surfaces during exposure to the atmosphere, during exposure to low-vapor-pressure system components, and during surface passivation or stabilization treatments. The photoacoustic effect has proved to be useful quantitative technique for the measurement of surface optical absorption and, when using a carbon dioxide laser source, provides a sensitivity of a few percent of one monolayer for vapor molecules chemisorbed on highly transparent substrates.
The work reported here involves an application of photoacoustic spectroscopy to surface absorption studies of high power laser window materials. Results are presented for the time dependence of surface absorption during controlled vapor exposure and for the wavelength dependence of surface absorption, in the 9–11 μm range, following atmospheric contamination. The application of these techniques to the determination of adsorption rate constants, activation energies, and the chemical identification of surface impurities is discussed.
Wavelength and Temperature Dependence of the Absolute Reflectance of Metals at Visible and Infrared Wavelengths
Authors: Decker DL , Hodgkin VA 
Published: March 2009

This paper presents the wavelength dependence of Ag, Cu, and Al from 4000 Å to 10 μm wavelength. An intercomparison of data is made for surfaces prepared with a variety of techniques, including vacuum evaporation and diamond single-point machining. Briefly described, also, are experimental techniques and apparatus developed at the Naval Weapons Center for measuring temperature-dependent changes in the near-normal incidence reflectance of a sample to a precision of a few parts in 105. Reflectance results obtained from this instrument are presented for films and bulk material over the same wavelength range as above at temperatures from 270 to 450 K. The sample and reference surfaces were protected in ultrahigh vacuum for these measurements.
A theoretical interpretation of results is presented, including both inter- and intraband electron transition effects, as well as extrinsic surface roughness effects. Of much practical interest for laser mirror applications, especially for pulsed mode operation, is the behavior of many metals upon temperature cycling, including hysteresis and time-dependent “annealing” behavior. Similar effects are also observed in both transport and thermal properties and are generally described under the name “premelting effects.”
The data presented in this paper are of immediate engineering value in computing the performance of optical systems whose components necessarily operate at temperatures other than room temperature. It is also hoped that it will stimulate theoretical interest in examining some of the subtle and poorly understood dispersion effects such as those seen in the near-infrared in silver.
Absorption Calorimetry and Laser Induced Damage Threshold Measurements on Germanium and Zinc Selenide
Authors: Foley J , Sharma SK , Wood RM 
Published: March 2009

It has been shown that the absorptance of coated and uncoated germanium samples varies with surface state and ambient atmosphere. Absorption measurements made in air are up to 50% higher than identical measurements made under vacuum. The removable surface absorption on germanium has been shown to be due to both hydrocarbon and water layers, depending on the previous cleaning and ambient conditions. The residual surface absorption depends on the surface polishing procedure. Bulk absorption levels as low as 0.007 cm−1 have been measured for freshly cleaned samples. Correlation between the surface condition and the laser induced damage thresholds at 10.6 μm indicates that the damage threshold should be significantly higher in vacuum.
Absorption and laser induced damage threshold measurements have been made on a range of CVD grown ZnSe substrates. Correlation has been shown between the grain size and the direction of measurement and the bulk absorption coefficient.
Survey of Damage Thresholds at 532 NM for Production-RUN optical Components
Authors: Deaton TF , Rainer F , Milam D , Smith WL 
Published: March 2009

We report the results of a survey of 532-nm, 0.7-ns damage thresholds for a variety of optical components. The optics were all samples from current production runs, which included high-reflector and anti-reflector films, beam dumps, leached AR surfaces, and multiwavelength AR and HR films.
The experiment was similar to the usual 1064-nm damage measurement. The green light pulses were produced by frequency-doubling 1-ns pulses from a Nd:glass laser. The 532-nm beam was then focused to a spot size of about 2 mm diameter at the sample. Beam profiles were recorded on a vidicon and on 1-Z photographic plates.
Thresholds for the AR and HR films were typically 2–5 J/cm2, somehwat lower than might have been expected. Some of the beam dumps damaged at 2 J/cm2. Bare and graded-index surface thresholds were found to be comparable to 1-ns, 1064-nm thresholds.
Design and Construction of Three Infrared Ellipsometers for Thin-Film Research
Authors: Leonard TA , Loomis J , Harding KG , Scott M 
Published: March 2009

The University of Dayton Research Institute (UDRI) has designed and is building three infrared ellipsometers in support of the Air Force high-energy laser program. One of these instruments is a conventional null type elliposmeter for operation in the 3.39 to 4.00 μm wavelength range. Ellipsometric parameters are determined with a precision of 0.01° at any angle of incidence from 20° to 85°. Repeatability and absolute accuracy also approach 0.01° which yields optical constants accurate to 0.1 percent in some cases. All components are mounted on removable carriers for easy interchange, although operation is normally in the PCSA (Polarizer, Compensator, Sample, Analyzer) configuration.
The system software has special provisions for the second instrument which is also a null type ellipsometer dedicated to monitoring vacuum deposited coatings in real time at 3.39 μm. The software can model non-ideal components in the optical path using Jones or Mueller matrices and provide completely corrected data with a single zone measurement after the instrument is characterized. The third instrument is a rotating polarizer, automated ellipsometer tunable from 1 to 12 μm. A dedicated computer operates the instrument and reduces data.
The Role of Laser-Induced Primary Defect Formation in Optical Breakdown of NaCl
Authors: Bräunlich P , Brost G , Schmid A , Kelly P 
Published: March 2009

Rapid and efficient formation of primary defects (Vk-, F-1, and H-centers, self-trapped excitons) influences the kinetic processes involved in laser-induced optical breakdown in alkali halides. These processes have been studied for the case of NaCl exposed to short (30 psec to 30 nsec) laser pulses at λ = 532 nm wavelength.
Rapid defect formation acts as a drain on the free electrons and holes, produced by multiphoton absorption in the laser photon field. As a consequence, the rate of temperature increase of the lattice by free or “dressed” carrier absorption is reduced and, thus the damage threshold is increased. This effect is compensated by additional channels of energy deposition to the lattice which are provided by formation of and photon absorption by the generated primary defects.
The net effect of the photochemical processes of primary defect formation is a slight reduction in the damage threshold and a marked decrease of the free carrier densities required for damage to occur. Beam deformation, caused by free-carrier induced changes of the dielectric function, should therefore be less pronounced than that predicted by model calculations of laser damage in the absence of primary defect formation.
Laser Damage of Crystalline Silicon by Multiple 1.06μm, Picosecond Pulses
Authors: Walser RM , Becker MF , Sheng DY 
Published: March 2009

Recent studies [1] have shown that the iso-intensity damage kinetics of crystalline silicon irradiated by picosecond 1.06μm pulses could be fit to the equations of classical nucleation and growth. These results suggested that laser damage be viewed as a non-equilibrium phase transition in which the threshold intensity produced excursions across a first order phase boundary into a metastable region of the material phase diagram.
In the present work we discuss a simplified electronic phase diagram for silicon that we believe is relevant to the picosecond damage experiments. The physics of the metastable region are as yet uncertain, but its presence requires that the statistics of laser damage be determined by the activated nucleation of embryos (charge density fluctuations) to near liquid phase charge densities.
The thermodynamic perspective suggests a new laser damage mechanism in which incident photons are resonantly absorbed by the collective electronic oscillations (surface plasmons) of critical embryos. Evidence supporting this mechanism has been obtained from high resolution SEM studies of the damage morphology showing that a coherent radiative interaction occurred between resonant surface plasmon embryos on adjacent sites just prior to liquid-like phase nucleation. Calculations show that the surface plasmon of a spherical embryo with a near liquid charge density of ∼2 × 1022/cm3 is resonantly coupled to the laser photons.