bluuebunny/crossref_metadata_2025 huggingface dataset:
Method for the Classification of Biological FT-IR Spectra Prior to Quantitative Analysis
Authors: Cadet Frédéric
Published: August 2005

Several methods have been proposed with the aim of improving the precision of quantitative measurements of biological components (baseline correction, classification, elimination of unwanted components, etc.). In this context, we propose a classification method of biological samples (raw sugar cane juices) before sucrose content prediction is performed. The method consisted of isolating the two most dissimilar individuals from a large calibration family of mid-FT-IR spectra, and, by successive principal component analysis (PCA) and principal component regression (PCR), a family composed of a few individuals was constituted. Each individual from this family represented the first spectrum of the corresponding classes that were ultimately formed. The classification of the remaining samples from the calibration family was carried out by the mobile centers method, that is, by the measurements of the Euclidian distances. This procedure improved the precision of the predictions. The mean and standard deviation (SD) of the differences between predicted and reference values were, respectively, −1.62 × 10−3 and 0.308 before classification and 2.38 × 10−3 and 0.254 after classification. The procedure developed in this paper first allowed a qualitative classification of spectra without knowledge of their chemical composition, and second, improved the precision of the quantitative predictions.
Raman Mapping of the Dentin/Adhesive Interface
Authors: Wieliczka D. M. , Spencer P. , Kruger M. B.
Published: August 2005

The degree of adhesive penetration into dentin has been studied through micro-Raman spectroscopic examination of the dentin/adhesive interface. In contrast to previous studies, for the specimen examined in this work the adhesive penetrates less than 2 μm into the acid-etched and, thus, decalcified dentin. There is strong spectroscopic evidence that, upon acid etching of the dentin surface, which is typically performed immediately before the adhesive is applied, the collagen matrix collapses upon itself.
Effect of Sampling Geometry on Elemental Emissions in Laser-Induced Breakdown Spectroscopy
Authors: Multari Rosalie A. , Foster Leeann E. , Cremers David A. , Ferris Monty J.
Published: August 2005

In laser-induced breakdown spectroscopy (LIBS), a focused laser pulse is used to ablate material from a surface and form a laser plasma that excites the vaporized material. Geometric factors, such as the distance between the sample and the focusing lens and the method of collecting the plasma light, can greatly influence the analytical results. To obtain the best quantitative results, one must consider this geometry. Here we report the results of an investigation of the effect of sampling geometry on LIBS measurements. Diagnostics include time-resolved spectroscopy and temporally and spectrally resolved imaging using an acousto-optic tunable filter (AOTF). Parameters investigated include the type of lens (cylindrical or spherical) used to focus the laser pulse onto the sample, the focal length of the lens (75 or 150 mm), the lens-to-sample distance (LTSD), the angle-of-incidence of the laser pulse onto the sample, and the method used to collect the plasma light (lens or fiber-optic bundle). From these studies, it was found that atomic emission intensities, plasma temperature, and mass of ablated material depend strongly on the LTSD for both types of lenses. For laser pulse energies above the breakdown threshold for air, these quantities exhibit symmetric behavior about an LTSD approximately equal to the back focal length for cylindrical lenses and asymmetric behavior for spherical lenses. For pulse energies below the air breakdown threshold, results obtained for both lenses display symmetric behavior. Detection limits and measurement precision for the elements Be, Cr, Cu, Mn, Pb, and Sr, determined with the use of 14 certified reference soils and stream sediments, were found to be independent of the lens used. Time-resolved images of the laser plasma show that at times >5 μs after plasma formation a cloud of emitting atoms extends significantly beyond the centrally located, visibly white, intense plasma core present at early times (<0.3 μs). It was determined that, by collecting light from the edges of the emitting cloud, one can record spectra using an ungated detector (no time resolution) that resemble closely the spectra obtained from a gated detector providing time-resolved detection. This result has implications in the development of less expensive LIBS detection systems.
2H NMR Spectra for D2O Adsorbed on Oriented Cellulose Fibers
Authors: Li Tie-Qiang
Published: August 2005

2H NMR spectra for D2O adsorbed on cellulose fibers which are macroscopically oriented demonstrate that the axis of cellulose fibers can be regarded as the director of the average molecular motion of the adsorbed D2O. The spectra for samples prepared from fiber sheets depend on the orientation of the sheets with respect to the magnetic field as well as the fiber orientation in the sheets. When the sheets are oriented perpendicular to the magnetic field, all the fibers in the sheets are perpendicular to the field irrespective of the fiber orientations in the sheets, and a partially overlapped quadrupole splitting is observed. When the sheets are oriented parallel to the magnetic field, the observed spectra deviate significantly from the expected 2D powder patterns, and the distribution of fiber orientations in the sheets has a significant influence on the observed band shape. An N-site mutual exchange model was used to account for the lateral diffusion of water molecules from one fiber to another. In a comparison of the simulated spectra based on the N-site mutual exchange model with the experimentally recorded spectra, the average lifetime for the adsorbed D2O molecules to reside on cellulose fibrils was estimated to be about 1.5 ms.
Real-Time Photoacoustic Signal Analysis in a Gas-Phase Spectrophone: A Feasibility Study
Authors: Bellaiche-Sharpe P. , Gough K. M. , Schattka B. J. , MaCdonald T. , Rustenburg J. , Struyk A. , McDonnell G.
Published: August 2005

A digital signal processing (DSP) system has been constructed for the acquisition of intracavity dye laser photoacoustic spectra (ICL-PAS). The DSP system permits observation of the real-time PA pulse, an arrangement which facilitates the adjustment of all spectral acquisition parameters as well as signal processing for noise reduction. Sample spectra of the real-time PA pulse illustrate the improvements possible with Fourier filtering and time-averaging. Spectra of the region of the fifth CH stretching overtone of ethene, benzene, and propane in the gas phase are presented. The system offers significant potential advantages in signal quality, signal processing, and construction cost over the more conventional lock-in amplifier detection method.
EPR Spectroscopy of Adsorbed Nitroxides to Investigate Catalyst Surfaces
Authors: Lunina E. V.
Published: August 2005

The use of electron paramagnetic resonance (EPR) for the investigation of catalytic surfaces by means of adsorbed nitroxides is discussed. The possibilities of the paramagnetic probe method in terms of qualitative and quantitative control of the acidity of the catalyst surfaces is demonstrated. Models of the acid site structures in accordance with EPR data are presented.
Dynamic Infrared Linear Dichroic Spectra of Prestretched Polypropylene
Authors: Ingemey R. A. , Strohe G. , Veeman W. S.
Published: August 2005

DIRLD (dynamic infrared linear dichroic) spectra of prestretched isotactic polypropylene have been recorded. The line shape features in the in-phase spectra are described on the basis of frequency shifts and absorption amplitude variations during the stretching cycle. Details such as the dichroism of the bands, direction of the shift, and changes in the absorption intensities must be considered to explain signs and shapes of the DIRLD bands. Evidence for chain reorientations under stress has not been found. The general principle of frequency shifts and changes in absorption intensities as the origin of DIRLD bands is demonstrated by spectral simulations.
Distinct Fine Structure in NMR Spectra of Diffusing Molecules in Solids: Applications to Zeolites and Graphite Intercalation Compounds
Authors: Panich A. M.
Published: August 2005

High resolution in the NMR spectra of diffusing molecules in graphite intercalation compounds, zeolites, crystalline solvates, and hydrates is achieved because of the selective motional averaging of the intermolecular dipole–dipole interactions. An analysis of such spectra yields information about molecular motion and arrangement, as well as chemical shift anisotropy.
Spectrochemical Behavior of Carcinogenic Polycyclic Aromatic Hydrocarbons in Biological Systems. Part II: A Theoretical Rate Model for BaP Metabolism in Living Cells
Authors: Chiang Ping , Li Kuang-Pang , Hseu Tong-Ming
Published: August 2005

An idealized model for the kinetics of benzo[ a]pyrene (BaP) metabolism is established. As observed from experimental results, the BaP transfer from microcrystals to the cell membrane is definitely a first-order process. The rate constant of this process is signified as k1. We describe the surface–midplane exchange as reversible and use rate constants k2 and k3 to describe the inward and outward diffusions, respectively. The metabolism is identified as an irreversible reaction with a rate constant k4. If k2 and k3 are assumed to be fast and not rate determining, the effect of the metabolism rate, k4, on the number density of BaP in the midplane of the microsomal membrane, m3, can be estimated. If the metabolism rate is faster than or comparable to the distribution rates, k2 and k3, the BaP concentration in the membrane midplane, m3, will quickly be dissipated. But if k4 is extremely small, m3 will reach a plateau. Under conditions when k2 and k3 also play significant roles in determining the overall rate, more complicated patterns of m3 are expected.
129Xe and 131Xe NMR of Xenon in Mesophases of Cetyltrimethylammonium Bromide in Formamide
Authors: Ylihautala Mika , Ingman Petri , Jokisaari Jukka , Diehl Peter
Published: August 2005

For the first time, noble gas NMR has been applied to a study of a lyotropic liquid crystal. 129Xe and 131Xe NMR spectra of natural xenon gas dissolved in pure formamide and three cetyltrimethylammonium bromide (CTAB)/formamide (FA) mixtures were recorded over wide temperature ranges. The CTAB/FA system forms micelles at low concentrations of CTAB and mesophases at higher concentrations and elevated temperatures. The phase transitions are observed in the series of xenon spectra. In addition, the free xenon gas signal is seen in the spectra at low temperature, when the CTAB/FA system has a coexisting solid/liquid phase. The gas signal indicates that Xe is not soluble in the solid but accumulates in macroscopic bubbles. The intensity variation of the central peak of the 131Xe NMR spectra shows the presence of a static external electric field gradient (EFG). However, the spectral satellites are not observed and, therefore, the magnitude of the EFG cannot be determined. The obvious reason for the missing 131Xe satellites is the orientation distribution of the EFG tensor leading to broadening of the satellites.
Analysis of the 1H NMR Line Shape Found in Animal Lenses
Authors: Bodurka Jerzy , Buntkowsky Gerd , Gutsze Aleksander , Bodurka Malgorzata , Limbach Hans-Heinrich
Published: August 2005

The proton NMR line shape of rabbit lens was investigated to explain the extremely short value of the T2 relaxation time that determines the decay time of the lens free induction decay (FID) signal. The proton lens spectra were measured at 300 MHz, and a characteristic, antisymmetric profile was found. To determine whether the line shape is caused by unaveraged residual dipolar interaction from immobile protein protons, which would yield a homogeneously broadened line, we performed a spectral hole-burning experiment on the lens. In these experiments we could show that the line is clearly inhomogenously broadened. The inhomogeneity of the external field (Δ B0) was excluded by comparing at room temperature (295 K) the normalized proton NMR line shape of the whole rabbit lens measured at 300 MHz with the NMR line of a reference sample of pure water of similar size and shape. The measurements of the NMR spectra of the lens cortex and nucleus alone, as well as the spin–lattice relaxation time data obtained for the lens at different frequencies, indicate that the distribution of the chemical shift values is not responsible for the lens profile. Therefore, to understand our data we have to assume that the magnetic susceptibility effect and the shape of the lens are responsible for the observed the NMR line shape and also for the short value of the T2 relaxation time. We calculated the magnetic field inside the lens, using the model of two concentric spheres with different susceptibilities. The results of these calculations are in very good agreement with the experimental data of the lens. The consistency of the assumed model was checked by measurements of the NMR line shapes for the lens phantom and for the lens at higher fields (500 MHz).
Characterization of a Polypropylene/Super-Absorbent Web by NMR Diffusion Studies
Authors: Zeng Lei , Stejskal E. O.
Published: August 2005

Super-absorbent fiber has the property of absorbing moisture up to several thousand times its original weight, undergoing significant expansion, and eventually becoming a gel. The hydrophilic super-absorbent fiber is usually blended with hydrophobic polymer fiber to form a polymer web with the ability to attract fluid and also to hold it under pressure. Because of the confining influence of pore boundaries on molecular translation, restricted diffusion measurements on fluids in porous systems, such as the super-absorbent web, contain important information about the pore morphology. In this work, we studied the diffusion of water in a web of super-absorbent polyacrylate and polypropylene fiber. We observed restricted diffusion of the water by means of the pulsed-field-gradient spin-echo (PFGSE) NMR technique. Several mathematical models were used to interpret the data and yield estimates of the gross pore dimensions and the surface-to-volume ratio of the pores.
Fiber-Optic Remote Multisensor System Based on an Acousto-Optic Tunable Filter (AOTF)
Authors: Moreau Frédérick , Moreau Sandrine M. , Hueber Dennis M. , Vo-Dinh Tuan
Published: August 2005

This paper describes a new fiber-optic multisensor based on an acousto-optic tunable filter (AOTF) and capable of remote sensing using a multioptical fiber array (MOFA). A two-dimensional charge-coupled device (CCD) was used as a detector, and the AOTF was used as a wavelength selector. Unlike a tunable grating or prism-based monochromator, an AOTF has no moving parts, and an AOTF can be rapidly tuned to any wavelength in its operating range within microseconds. The large aperture of the AOTF allows the optical signal from over 100 fiber-optic sensors to be measured simultaneously. These characteristics, combined with their small size, make AOTFs an important new alternative to conventional monochromators, especially for spectral multisensing and imaging. A prototype fiber-optic multisensor system has been developed, and its feasibility for simultaneous detection of molecular luminescence signal via fiber-optic probes is demonstrated.
Trace Analysis of NO2 in the Presence of NO by Laser Photofragmentation/Fragment Photoionization Spectrometry at Visible Wavelengths
Authors: Simeonsson J. B. , Sausa R. C.
Published: August 2005

Trace concentrations of NO and NO2 molecules are differentiated spectrally by using a visible dye laser and a simple flow cell with a pair of miniature electrodes for ion detection. NO is detected near 452 nm by (2+2) resonance-enhanced multiphoton ionization via its A2∑+-X2II (0,0) transitions, while NO2 is detected by laser photofragmentation with subsequent fragment NO ionization via the A2∑+-X2II (0,0) and (1,1) transitions. Spectral differentiation is possible since the internal energy of the NO photofragment differs from that of “ambient” NO. Measurement of vibrationally excited NO via its A2∑+-X2II (0,3) band is also demonstrated at 517 nm. Rotationally resolved spectra of NO and fragment NO are analyzed by using a multiparameter computer program based on two-photon energy level expressions and line strengths for A2∑+-X2II transitions. Boltzmann analysis of the P12 + O22 branch of the (0,0) band reveals that the rotational temperature of fragment NO is approximately 500 K compared to room-temperature NO. Limits of detection [signal-to-noise (S/N) = 3] of NO and NO2 are in the 20–40-ppbv range at 449.2, 450.7, and 452.6 nm for a 10-s integration time. The limit of detection of NO2 at 517.5 nm is 75 ppbv. The analytical utility of the technique for ambient air analysis is evaluated and discussed.
Use of Polarized Resonance Raman Spectroscopy of a Polyene Probe, and FT-IR Dichroism, to Probe Amorphous-Phase Orientation in Uniaxially Drawn Poly(Ethylene)
Authors: Everall Neil , Chalmers John , Mills Peter
Published: August 2005

The linear diphenyl polyene Φ–(C=C–)4Φ has been investigated as a resonant Raman-active probe for molecular orientation, suitable for incorporation into polymers prior to melt extrusion and drawing. By examination of the polarization properties of the Raman scattered radiation, it is possible to determine the P200 and P400 orientation parameters for the dye molecule as a function of draw ratio. Assuming that the dye resides only in amorphous polymer regions, it is expected that the data will give insight into the orienting forces present in the amorphous phase during processing. Expressions were derived relating P200 and P400 to the polarized Raman intensities. An expression for Hermans' orientation parameter was also derived—it was shown that f was always slightly higher than P200 when evaluated from the same Raman data. These Raman measurements were illustrated by using the example of uniaxially drawn poly(ethylene) (PE) tubing. As an alternative approach, FT-IR dichroic ratios of bands due to the PE itself were used to determine the orientation ( P200) of the crystalline phase and also of gauche conformers present only in the amorphous phase; these results were compared with the Raman measurements on the dye probe. The orientation was examined as a function of draw ratio and subsequent thermal annealing. In general, both crystalline and amorphous phases oriented increasingly with draw ratio, but whereas annealing the samples only slightly relaxed the crystal orientation, the amorphous orientation decreased dramatically when measured by using either the probe molecule or the gauche conformer as a probe of the amorphous phase. This result support the assumption that the dye is localized in amorphous regions. This work is important since it shows how a cheap, commercially available probe molecule may be used to probe the amorphous-phase orientation of a polymer without requiring any chemical synthesis; simple melt-mixing is sufficient to dope the amorphous network. This capability will be useful for systems where convenient vibrational band: specific to the polymer amorphous phase are absent.
Comparison of Direct-Deposition Supercritical Fluid and Gas Chromatography/Fourier Transform Infrared Spectra to Condensed-Phase Library Spectra
Authors: Norton Kelly L. , Haefner Andrew M. , Makishima Hideo , Jalsovszky George , Griffiths Peter R.
Published: August 2005

Comparisons of spectra from direct-deposition (DD) capillary gas chromatography (GC) and supercritical fluid chromatography (SFC)/Fourier transform infrared (FT-IR) measurements of two quinones with C2 symmetry axes and several barbiturates to spectra from condensed-phase libraries of the corresponding compounds are reported. The best spectral search results were obtained when the eluites were deposited on an amorphous substrate, such as ZnSe. A small number of polar, hydrogen-bonding compounds were found to align with each other or with a crystalline substrate. Different crystalline forms of some polymorphic analytes can also yield ambiguous identifications. These effects produce enough differences in the DD GC/FT-IR and SFC/FT-IR spectra to cause occasional incorrect identifications when the spectra are searched against KBr-disk library spectra.
Binding Properties of Near-IR Dyes to Proteins and Separation of the Dye/Protein Complexes Using Capillary Electrophoresis with Laser-Induced Fluorescence Detection
Authors: Legendre Benjamin L. , Soper Steven A.
Published: August 2005

The noncovalent binding of the near-infrared (NIR) dyes, DTTCI (cationic) and IR-125 (anionic), to several model proteins was investigated with the use of steady-state and picosecond laser fluorescence measurements. In an aqueous borate buffer (pH = 9.2), minimal fluorescence emission from these NIR dyes was observed. When a protein was added to the solution, enhancements in the fluorescence emission were found for both dyes. Time-resolved fluorescence measurements for IR-125 in the presence of the protein, β-casein, indicated a biexponential decay with lifetimes of 195 and 682 ps (χ2 = 1.94). Our data suggest that these dyes distribute themselves between the hydrophobic core of the protein and the interstitial aqueous solution. The dye molecules residing in the interior of the protein exhibit enhancements in their fluorescence due to a more favorable microenvironment. The binding and enhanced fluorescence properties allowed the use of these dyes as noncovalent stains for the low-level detection of proteins separated via capillary electrophoresis (CE). Detection limits for some model proteins separated by CE and stained with these NIR dyes were found to be superior to those obtained by using UV detection in CE.
Complete Optical Analysis to Obtain the Absorption Coefficient of the Interstitial Oxygen Vibration in Silicon
Authors: Gunde Marta Klanjšek
Published: August 2005

The concentration of interstitial oxygen in single-crystal silicon is linearly dependent on the absorption coefficient of the corresponding local vibration in the infrared. This absorption coefficient is usually determined from the spectral absorbance. Optical and geometrical parameters of the investigated sample influence the measurements and lower the determination precision. Instead of this standard method, the application of complete optical analysis for the investigated sample is shown. The proposed method overcomes most problems that are involved in the standard procedure. The thickness and degree of rear surface damage of the reference sample are immaterial. The error of the standard determination procedure is discussed in terms of its dependence on the degree of sample surface damage.
Simultaneous Two-Dimensional Visualization of Soot and OH in Flames Using Laser-Induced Fluorescence
Authors: Bengtsson Per-Erik
Published: August 2005

Two-dimensional visualization of soot has been realized in flames with the use of laser-induced fluorescence in C2 from laser-vaporized soot [LIF(C2)LVS]. Soot particles are heated to vaporization temperatures by the absorption of laser radiation. C2 radicals produced by this process are excited at wavelengths around 563 nm through the transition v’ = 0 d3Πg ← v” = 1 a3Πu, and the subsequent fluorescence at ∼516 nm is detected. By frequency-doubling of the laser radiation, wavelengths around 281.5 nm are achieved, which can excite OH radicals to the v’ = 1 A2∑+ state from v” = 0 X2Π, with subsequent fluorescence at ∼310 nm. With the use of both these excitation wavelengths, and a Cassegrainian split-mirror telescope as the imaging detection system in front of the charge-coupled device (CCD) camera, simultaneous two-dimensional single-shot images of soot and OH were obtained on a single CCD chip, thus enabling both sooting regions and reaction zones in flames to be monitored.
Near-Infrared Spectroscopic Measurements of Structural Changes in Starch-Containing Extruded Products
Authors: Millar S. , Robert P. , Devaux M. F. , Guy R. C. E. , Maris P.
Published: August 2005

Near-infrared spectroscopy was evaluated as a means of following physical and chemical changes in starch during the extrusion cooking of wheat flour under the Measurements and Testing Program of the European Commission. With the use of principal component (PC) and canonical correlation (CC) analyses, samples could be classified according to the severity of the extrusion cooking conditions. An interpretation of the spectra showed that the different processing conditions modified the physical structure of the starch molecules. At low values of specific mechanical energy inputs, starch was partially crystalline and the near-infrared spectra exhibited characteristic absorption bands at about 1428, 1520, and 1587 nm. As the energy inputs increased, causing a change to molten starch, the intensity of the bands at 1520 and 1587 nm decreased, with a shift of the 1428-nm absorption band towards longer wavelengths also being observed. The changes that occurred were thought to be due to a disruption of the intra- and intermolecular hydrogen bonding of the starch. At the higher levels of specific mechanical energy inputs, the starch molecules underwent further structural modification, resulting in their partial degradation.
Use of Shift Reagents to Determine Enantiomers by Near-Infrared Analysis
Authors: MacDonald Stacy A. , Hieftje Gary M.
Published: August 2005

A method is described that utilizes β-cyclodextrin and silica gel as shift reagents to distinguish between enantiomers by means of near-infrared transmission spectroscopy. The premise is that the spectrum of the (+)-enantiomer bound to the shift reagent will be different from that of the (−)-enantiomer bound to the same reagent. With the use of principal component analysis, the difference between the enantiomers can be distinguished. The resulting method is fast, simple, and of potential application in pharmaceutical process control.
Mechanistic Quality Management of Hot Mix Asphalt Layers with Seismic Methods
Authors: Nazarian S , Tandon V , Yuan D
Published: August 2005

Realistic field-test protocols and equipment, which in a rational manner, combine the results from laboratory and field tests with those used for quality control during construction, have been developed. Seismic nondestructive testing technology has been used for this purpose. Simple laboratory tests that are compatible with the field tests have been recommended. All these tests have several features in common. They can be performed rapidly (less than 3 min.), and their data reduction processes are simple and almost instantaneous.
Laboratory Investigation of HMA Performance Using Hamburg Wheel Tracking and DSR Torsional Creep Tests
Authors: Reinke G , Glidden S , Herlitzka D , Jorgenson J
Published: August 2005

Lack of existing fundamental mechanistic tests to evaluate performance potential of HMA mixtures has given rise to a number of empirical and mechanical-empirical test procedures. In an effort to understand how one of these tests, the Hamburg rutting test, was impacted by differences in HMA mixture variables, the following experimental work was conducted. Three aggregate types consisting of a crushed granite, a crushed siliceous gravel, and a crushed limestone were evaluated at four design ESAL levels. These four ESAL levels were 300 000, 1 million, 3 million, and 10 million. For each of these aggregate types and ESAL levels, 5 PG graded binders were investigated. The binders were PG 58-28, PG 64-28C (chemically modified), PG 64-28P, PG 64-34, and PG 70-28; the latter 3 binders were polymer modified. For all mixtures, Hamburg Wheel Tracking tests were performed under water at 50°C. In addition, a DSR Creep Test developed at MTE was performed on each mixture at 58°C and 34 kPa stress to determine the dry strength characteristics. The Hamburg test showed consistently better results as the ESAL level of the mix increased and as the high temperature PG grade of the binder increased for a given base asphalt. In the Hamburg test, mixes produced with PG 64-34 did not perform as well as PG 70-28 or PG 64-28P, while in the DSR Creep Test, mixes produced with PG 64-34 performed significantly better than PG 64-28P. This leads to speculation that the modulus of the base asphalt plays a more significant role in stress applied moisture resistance tests and that dry high temperature permanent deformation tests are influenced by the modified binder properties.
Characterization of Asphalt Concrete by Multi-Stage True Triaxial Testing
Authors: Wang L , Hoyos LR , Mohammad L , Abadie C
Published: August 2005

The feasibility of an existing servo-controlled true triaxial (cubical) apparatus for evaluating the mechanical response of nominal 4-in. cubical specimens of asphalt concrete (AC) under multi-axial stress states has been investigated. The apparatus allows the testing of specimens along a wide range of stress paths and stress levels that are not achievable in a conventional uniaxial or cylindrical apparatus. A multi-stage testing scheme can be followed by simultaneous control of the major, intermediate, and minor principal stresses directly applied to the specimens. Two cubical AC specimens cut from two WestTrack block samples were subjected to a series of multi-stage stress paths that included triaxial compression (TC), triaxial extension (TE), simple shear (SS), conventional triaxial compression (CTC), conventional triaxial extension (CTE), and cyclic conventional triaxial extension (CCTE). Experimental data were analyzed to assess volumetric creeping properties, resilient response, plastic deformation response, Poisson's ratio, loss angle, and dilatancy of asphalt concrete under general stress states. Test results highlight the potential of the cubical cell for mechanical characterization of asphalt concrete in a broad range of applications involving true triaxial stress states. Analysis of test results indicates all of the following: (a) Modulus of AC shows significant anisotropy in different orientations; (b) Volumetric creeping of AC is considerably significant at relatively high pressures; (c) AC shows significant dilatancy; and (d) Cubical Device can distinguish mixes of different performance.
Destruction of Crystallographic Texture in Zirconium Alloy Tubes
Authors: Grytsyna V , Stukalov A , Chernyayeva T , Krasnorutskyy V , Malykhin D , Voyevodin V , Bryk V
Published: August 2005

The paper investigates the dependence of the transformation texture of Zr-2.5wt%Nb tubes and rods on the initial texture, the method of heating (furnacing, conductive heating, inductive heating) and cooling (furnace cooling, water quenching, water shower), stress, and thermal cycling. It was demonstrated that the primary factors determining the transformation texture are the initial texture and the heating rate for quenching. From the investigation results, a method of final thermal treatment of finished zirconium reactor core components (pressure tubes, guide tubes, and cladding fuel rods) is suggested, allowing the destruction of their texture without changing the well-established manufacturing process. The suggested SHF heating includes the use of the α→β→α transformation with fast heating up to the β-phase, subsequent quenching for texture destruction, and annealing for transformation from the metastable α'-state to the equilibrium double-phase αZr + βNb state.
Microstructural and Mechanical Characterization of Radiation Effects in Model Reactor Pressure Vessel Steels
Authors: Ulbricht A , Böhmert J , Viehrig H-W
Published: August 2005

This paper presents results of radiation-induced nanoscale microstructural changes measured by Small-Angle Neutron Scattering (SANS) on ASTM-type reactor pressure vessel (RPV) steels. Five different base metals and one weld metal were investigated. The irradiation was performed in a VVER-type power reactor to three different dose levels, maximally 0.14 dpa, at an irradiation temperature of 255°C. The volume content of the micostructural features measured is correlated with the irradiation hardening and embrittlement.

In every case clear radiation-related hardening, embrittlement, and microstrucural effects are proven. Radiation produces nanoscale scattering defects of a radius between 0 < R < 3 nm with the maximum near R = 1 nm. Fluence and chemical composition do not or hardly change the shape of the size distribution but strongly influence the volume fraction. The radiation sensitivity is mainly influenced by the copper content. Copper also increases the A-ratio. There are good correlations between volume fraction of the nanoscale radiation defects and the radiation hardening or embrittlement.

Annealing at 475°C produces almost full recovery of the mechanical properties. However, the original microstructure of the unirradiated state is not completely reproduced.
Plastic Deformation of Irradiated Zirconium Alloys: TEM Investigations and Micro-Mechanical Modeling
Authors: Onimus F , Béchade J-L , Prioul C , Pilvin P , Monnet I , Doriot S , Verhaeghe B , Gilbon D , Robert L , Legras L , Mardon J-P
Published: August 2005

TEM investigations have been performed on irradiated samples after deformation covering various testing conditions for different recrystallized Zr alloys. It is shown that for transverse tensile tests and internal pressure tests performed at 350°C, only basal channels are observed for strain levels up to uniform elongation, whereas only prismatic and pyramidal channels are observed for axial tensile test. Then, focusing on internal pressure testing, irradiation hardening and strain hardening behavior have been analyzed in detail and compared to TEM observations. It is proposed that dislocation channeling phenomenon leads to high strain incompatibility between channels and surrounding grains and therefore to high microscopic internal stresses. These high microscopic internal stresses are believed to induce strong kinematic hardening at the macroscopic scale, as suggested by the mechanical behavior analysis. Finally, a micro-mechanical model based on microscopic deformation mechanisms and using homogenization techniques is proposed, taking into account the observed channeling phenomenon.
Deformation Mechanism Maps of Unirradiated and Irradiated V-4Cr-4Ti
Authors: Li M , Zinkle SJ
Published: August 2005

This paper addresses various deformation mechanisms of unirradiated and irradiated V-4Cr-4Ti in terms of Ashby-type deformation maps. Tensile tests were carried out in the temperature range of 950–1150°C at strain rates of 10−3, 10−4, and 10−5 s−1. In addition, published tensile data and thermal creep data before and after irradiation were analyzed to provide further information about the materials' deformation behavior. The extensive tensile database for V-4Cr-4Ti was used to determine the key material parameters in physically-based constitutive equations. The resultant constitutive equations were employed to construct the Ashby deformation mechanism maps for unirradiated and irradiated V-4Cr-4Ti. Using the data analysis from the tensile tests, deformation map predictions at slow strain rates were obtained and verified by comparison with the experimental creep results. The methodology was successful in identifying the operating deformation mechanisms for a given temperature, stress, or strain rate condition. The study examines the limitations of extending creep data and analysis into new operating regimes, particularly where different deformation mechanisms are involved. The application of deformation mechanism maps in creep testing and data analysis is discussed.
Water Resistance and Vapor Permeance of Weather Resistive Barriers
Authors: Butt TK
Published: August 2005

Weather-resistive barriers (WRBs) are typically used in exterior walls of low rise frame buildings under claddings such as stucco (cement plaster), wood and wood derived products, vinyl (PVC), and masonry veneer. WRBs are primarily intended to provide resistance to water that may penetrate the outer cladding. WRBs also provide resistance to passage of air to varying extents but generally are moderately permeable to water vapor. Traditional WRB materials were limited to asphalt saturated felts and papers, but polymeric sheets have taken a growing share of the market in recent years. There are also trowel-applied and rigid board WRBs. Little information is available about the comparable properties of commercially available materials or what to consider when selecting the appropriate product for a particular application. Both building code requirements and vendors' product information are inconsistent and confusing. This paper, which is limited to the properties of water resistance and water vapor permeance, provides information that may be helpful in understanding, selecting, and using weather resistive barriers.
A Design Methodology to Take Credit for Residual Stresses in Fatigue Limited Designs
Authors: Prevéy P , Jayaraman N
Published: August 2005

High cycle fatigue (HCF) performance of turbine engine components has been known for decades to benefit from compressive surface residual stresses produced by shot peening. Recently laser shocking and low plasticity burnishing (LPB) have been shown to provide spectacular fatigue and damage tolerance improvement by introducing deep or through-thickness compression in fatigue critical areas. However, the lack of a comprehensive design method that defines the depth and magnitude of compression required to achieve a design fatigue life has prevented surface enhancement from being used for more than a safeguard against HCF damage initiation. The present paper describes a design methodology and testing protocol to allow credit to be taken for the beneficial compression introduced by surface enhancement in component design to achieve a required or optimal fatigue performance.

A detailed design method has been developed that relates the required fatigue life, the mean and alternating applied stresses, and the damage in terms of Kf to the residual stress at the fatigue initiation site required for the targeted HCF performance. The method is applied to feature specimens designed to simulate the fatigue conditions in the trailing edge of a first stage low pressure Ti-6-4 compressor vane to provide the optimal trailing edge damage tolerance. A novel adaptation of the traditional Haigh diagram to estimate the compressive residual stress magnitude for optimal fatigue performance is introduced. Fatigue results on blade-edge feature samples are compared with analytical predictions provided by the design methodology.
Effect of Aging Treatments on the Tensile Properties of Ti-35Nb-7Zr-5Ta-(0.06–0.7)O Alloys
Authors: Qazi JI , Tsakiris V , Marquardt B , Rack HJ
Published: August 2005

Ti-35Nb-7Zr-5Ta rods containing 0.06, 0.46, and 0.68 wt.% oxygen were produced by vacuum arc melting and forging. These were solution treated (ST) and aged in the temperature range of 427–593°C for 8 h followed by air cooling. Increasing oxygen content increased the ST yield strength (YS) from 530 to 1081 MPa. The largest increase in YS, 630MPa, in ti-35Nb-7Zr-5Ta-0.06O observed after aging at 427°C was associated with ω phase precipitation. While the largest increases in YS, (1060 and 1288 MPa, in Ti-35Nb-7Zr-5Ta-0.46/0.68O) observed after aging at 482°C were associated with fine and somewhat inhomogeneous precipitation of the α phase, the tensile elongation remained above 8%. Aging at 538 or 593°C led to an increase in the inhomogeneity in α phase precipitation in Ti-35Nb-7Zr-5Ta-0.46/0.68O, precipitate free zones clearly being observed along with prior β grain boundaries, which served as preferred paths for early crack propagation and decreased tensile ductility.
Development and Evaluation of a TG/DTA/Raman System
Authors: Collins WJ , DuBois C , Thomas Cambron R , Redman-Furey NL , Bigalow Kern AS
Published: August 2005

Modification of a commercially available TG/DTA instrument enabled development of a working TG/DTA/Raman system. The TG/DTA was modified by replacing a portion of the furnace wall above the sample and reference holders with a double layer insulated quartz window. The quartz window provided ready access for Raman spectroscopy, enabling simultaneous collection of TGA, DTA, and Raman data during thermal analytical experiments. Insertion of the quartz glass window did not impact TGA or DTA performance as demonstrated by the comparison of baseline drift and temperature calibration for modified and unmodified furnaces.
Characterization Of Epoxy Curing Using High Heating Rate DSC
Authors: Bilyeu B , Brostow W , Menard KP
Published: August 2005

Two common techniques to characterize the curing reaction of an epoxy as a function of time and temperature are heat of reaction and the shift in glass transition. These techniques can both be performed by Differential Scanning Calorimetry. However, both techniques share a common limitation, namely that the curing exotherm may occur during the ramp to isothermal temperature or may overlap with the glass transition event. Since the curing reaction and thus the exotherm is a kinetic event, it is rate dependent. As faster rates are used, the scan can be completed before the onset of the reaction. In an isothermal heat of reaction study, the material can be brought to temperature fast enough that the curing reaction does not begin until it is at temperature. Also, since the glass transition can be measured at high scanning rates, it can be measured before the curing reaction begins. At 100°C/min, the two overlapping events are separated, whereas at 200°C/min, the curing does not occur in the temperature range studied. The glass transition temperature can be measured without affecting the degree of cure, or the exotherm can be shifted to separate it from the glass transition for accurate measurement of enthalpy and the glass transition.
Corrosion of Modular Titanium Alloy Stems in Cementless Hip Replacement
Authors: Urban RM , Gilbert JL , Jacobs JJ
Published: August 2005

Severe, localized corrosion of titanium-alloy femoral stems has been reported for specific designs of hip prostheses intended for fixation using acrylic cement. The purpose of the present study was to examine the possibility that corrosion might also occur when titanium-alloy stems are inserted without cement, but the body of the stem is modular in design. Fourteen (7 primary and 7 revision) cementless, modular-body, titanium-6% aluminum-4% vanadium alloy femoral stems of similar design were removed at revision surgery after 2 to 108 months in situ. The reason for removal was unexplained pain (4), femoral or acetabular loosening (4), infection (3), recurrent dislocation (2), or component malposition (1). The devices and, in selected cases, tissue from the joint psuedocapsule were studied with the use of light and scanning electron microscopy. Fretting corrosion products were characterized using energy dispersive x-ray analysis, selected area diffraction, and micro-Raman spectroscopy. Damage at the modular body connections was absent in 3 stems, mild in 6, moderate in 4, and severe in 1. The surface damage was characterized predominately by fretting scars and by pitting and etching. Thick deposits of mixed titanium oxides were found adherent to the stem at the sites of corrosion and as 0.01 to 200 micrometer particles within histiocytes and multinucleated giant cells in the joint pseudocapsule. Fretting corrosion at the modular-body junctions of titanium-alloy femoral stems can generate solid degradation products, adding to the particulate burden of the periprosthetic tissues and potentially accelerating bearing-surface wear by a third-body mechanism. Both of these features can potentiate the development and progression of osteolysis. In addition, fretting corrosion can increase the potential for structural failure of the device. These findings stress the importance of the design of modular junctions to minimize corrosion and the generation of corrosion products.
Effect of Microbial Contamination of Water-Based Metalworking Fluids on the Aerosolization of Particles and Microbial Fragments
Authors: Reponen T , Wang HX , Grinshpun SA
Published: August 2005

Aerosolization of particles from metalworking fluids (MWFs) was studied using a laboratory-scale set-up that simulates grinding operations. Semi-synthetic MWF and soluble oil were contaminated with Pseudomonas fluorescens, and the aerosolized particles were measured using a photometric mass monitor, optical particle counter, and a condensation nucleus counter. Microbial contamination of both semi-synthetic MWF and soluble oil increased the mass concentration as measured by the photometric aerosol mass monitor and the fine particle number concentration as measured by the condensation nucleus counter. These effects were seen most clearly for the fine size range of particles aerosolized from contaminated semi-synthetic MWF. Endotoxin results indicate that the increase in the fine particle concentration occurs at least partially due to the increase in the microbial cell wall components (fragments).
Modified Heat of Combustion Measurement for Electrical Communications and Optical Cables
Authors: Fang X , Gandhi PD , Chapin TJ
Published: August 2005

A modified method to measure heat of combustion of electrical communications and optical cables has been evaluated using an oxygen bomb calorimeter. The test procedures described by the NFPA 259 and the ISO 1716 have been widely used to measure the heat of combustion of building materials. Both methods require samples to be pulverized prior to testing. The modified measurement discussed in this paper provides a convenient and reliable test method to measure the heat of combustion of cables without pulverization. The cables used in this study cover a wide range of fire performance categories, including vertical tray, riser, plenum, and limited combustible ratings. The results from traditional pulverized samples are also reported for comparison. The acid correction and copper effect on the measurement of the final heat of combustion of cables are addressed in this study. The results show that the modified measurement of heat of combustion is comparable with the traditional NFPA 259 and ISO 1716 methods, with reduced time and good repeatability.
Effects of Removing and Replacing an 8-MM Charpy Striker on Absorbed Energy
Authors: Vigliotti DP , Vigliotti JL
Published: August 2005

It has been thought that removing and replacing an in-tolerance 8-mm striker may affect the results of a Charpy test. This thought brought about a requirement in Standard Test Method E23 [1] that states that if a striker is removed and replaced on a Charpy machine, the indirect verification is void and a new verification test must be performed. Groups of NIST SRM 2092 and SRM 2096 specimens were tested on machines with three different striker-mounting designs. The specimens were tested with the striker removed and replaced between groups. The results of these tests support a change in the standard that can make removing and replacing the striker acceptable without performing a new indirect verification test.