bluuebunny/crossref_metadata_2025 huggingface dataset:
Infrared Spectra-Structure Correlations and Adsorption Behavior for Helix Proteins
Authors: Jakobsen Robert J. , Wasacz Frank M.
Published: July 2005

A vibrational assignment has been made for most of the observed bands of aqueous solutions of albumin. This assignment is based not only on past assignments, but on experimental justifications and the use of both the infrared and Raman spectra. With the use of these assignments, changes in the secondary structure of both myoglobin and albumin with adsorption can be followed. Changes in the adsorbed protein films indicate that both reversible and irreversible protein adsorption takes place under certain conditions. The presence of reversibly adsorbed proteins can affect the extent of unfolding of the irreversibly adsorbed protein film.
Visible Absorbance Microspectroscopy with a Raman Microprobe
Authors: Sommer A. J. , Martoglio P. A. , Katon J. E.
Published: July 2005

A Raman microprobe has been modified to function as a visible microspectrometer by the addition of an area-defining aperture and several neutral-density filters. The system enables visible absorbance spectra to be obtained on samples whose size is as small as ten micrometers in diameter. Several examples are presented which illustrate the capabilities and limitations of the modified system.
Construction of a Versatile Microsecond Time-Resolved Infrared Spectrometer
Authors: Iwata Koichi , Hamaguchi Hiro-O
Published: July 2005

A time-resolved scanning infrared spectrometer has been constructed which consists of a globar light source, a monochromator, an MCT detector, a boxcar integrator, a cw Q-switched Nd:YAG laser, and a personal computer. Both the time-resolved spectra (in the frequency-scanning mode) and the temporal change of the transient signals (in the time-scanning mode) can be observed with this spectrometer. It covers the spectral range of 700 to 4200 cm−1 with the time resolution of 1 μs. Intensity changes as small as one part in 104 can be detected with a slit width of 5 mm (6 cm−1 at 700 cm−1 and 60 cm−1 at 4000 cm−1) and with a typical scanning rate of 20 cm−1/min. High performance of this spectrometer has been achieved by the use of a high-repetition-rate (750 Hz) laser for the actinic light source combined with an ac-coupled detection scheme.
Infrared Study of Substituted Nitrobenzenes in Carbon Tetrachloride and Chloroform Solutions
Authors: Nyquist R. A. , Settineri S. E.
Published: July 2005

Both the νNO2 modes are affected by solute/solvent interaction for nitrobenzenes in CHCl3 and/or CCl4 1% or less solutions. The νasym. NO2 mode decreases in frequency in the order of physical phase: vapor, CCl4 solution, and CHCl3 solution. The νsym. NO2 mode generally increases in frequency in going from CCl4 solution to CHCl3 solution. However, in the few cases when the νsym. NO2 mode decreases in frequency, this frequency decrease is a factor of ∼0.5 or less than the frequency decrease for νasym. NO2. In cases where a C=O or a SO2 group is also joined to the 4-nitrophenyl group, the SO2 or C=O group is also affected by solute/solvent interaction. Physical factors such as intermolecular hydrogen bonding, dipolar effects, chemical effects, and steric factors of both solute and solvent appear to be involved in determining the degree of solute/solvent interaction.
CIRCLE CELL® FT-IR Analysis of Chemical Warfare Agents in Aqueous Solutions
Authors: Braue Ernest H. , Pannella Michael G.
Published: July 2005

The qualitative and quantitative FT-IR analyses of dilute aqueous solutions of the chemical warfare threat agents tabun (GA), sarin (GB), and soman (GD) were evaluated with the use of the CIRCLE CELL®. Infrared spectra were recorded with a Nicolet 60SXB FT-IR spectrometer fitted with a liquid-nitrogen-cooled MCT-A detector. The CIRCLE CELL® used a modified micro, high-pressure, flow-through sampling accessory fitted with a ZnSe internal reflection element. Peak heights were evaluated with the Nicolet SUPER QUANT program after spectral subtraction of the solvent. The P=O stretching absorption band, centered around 1240 cm−1, produced good quantification in the concentration range 0.5 to 2.0 mg/mL. In this concentration range the intra-daily precision had a percent coefficient of variation (% CV) of less than 3.0%, while the inter-daily precision yielded a % CV of less than 6.0%. The detection limit was observed to be 0.3 mg/mL for GA and 0.2 mg/mL for GB and GD.
Reduction of Convective Low-Frequency Noise in Thermal Lens Spectrometry
Authors: Alfonso E. F. Simó , Revert M. A. Rius , Alvarez-Coque M. C. García , Ramos G. Ramis
Published: July 2005

The construction and optimization of a thermal lens spectrometer with coaxial pump/probe configuration is reported. The low-frequency noise of convective origin is studied in detail, and it is demonstrated that a horizontal slit, instead of a pinhole, can be used as a simple way of reducing the noise to a negligible level without losing sensitivity.
Quantitative Determination of Resonant Raman Signals Using Signal Accumulation, Adapted Fourier Filtering, and Band-Shape Analysis
Authors: Bettermann H. , Rauch W.
Published: July 2005

The quantitative analysis of resonance Raman signals with small signal-to-noise ratios requires maximum reduction of noise. Since the time of digital signal accumulation is limited by the photochemical stability of the investigated compounds, further reduction of noise is achieved by Fourier filtering and band-shape analysis of the filtered spectra. The Fourier filtering is carried out by Gaussian filter functions, which are adapted to the recorded Raman spectra. With the use of intensity-normalized filter functions, the peak areas of the Raman lines are conserved by filtering and can be used for the signal quantification.
Investigation of the Complexation of Pyrene and Naphthalene with Hydroxypropyl-β-Cyclodextrin
Authors: Zung Jonathan B. , Ndou Thilivhali T. , Warner Isiah M.
Published: July 2005

The complexation of the now commercially available chemically modified cyclodextrin hydroxypropyl- β-cyclodextrin with pyrene and naphthalene is compared against the unmodified β-cyclodextrin with the use of fluorescence measurements. A pronounced difference in the complexation properties of the two cyclodextrins is observed for the interaction with both pyrene and naphthalene.
Wide Dynamic Range Detection with a Charge Injection Device (CID) for Quantitative Plasma Emission Spectroscopy
Authors: Bilhorn Robert B. , Denton M. Bonner
Published: July 2005

The operation and performance of an analytical plasma emission spectrometer based on an echelle polychromator and a charge injection device (CID) two-dimensional multichannel array detector is described. Quantitative analysis methodology for measuring the intensity of emission lines over a wide dynamic range is presented. The procedure involves varying the integration time on the detector for each spectral line, based on the intensity of that line, in a process called random access integration (RAI). The factors that determine the maximum number of spectral lines that may be simultaneously observed are presented. With current CID technology these include the size of the array, the intensity of spectral lines at the focal plane, and the size of the subarrays used to record the line intensities. The sensitivity and dynamic range of the system equal those of emission spectrometers employing photomultiplier tubes, and the flexibility to use any spectral line, or group of lines, for a particular element provides unprecedented ability to perform simultaneous multielement trace analysis in complex mixtures. Background intensity in the vicinity of each spectral line is measured simultaneously, enabling precise spectral background corrections. The simultaneous availability of the information from the entire emission spectrum allows spectral features of diagnostic value such as argon, hydroxide, and carbon emission to be monitored, as well as spectral features due to the principal components of the sample matrix. Changes in analysis conditions or matrix composition can be detected because of the availability of this additional information, thereby increasing the reliability of the analytical results.
Evidence of a New Spectral Line Intensity Formula for Optical Emission
Authors: Yngström Sten , Thelin Bo
Published: July 2005

Experimental evidence of a new intensity formula in optical emission spectroscopy is presented. The evidence is based on two different methods of data analysis. The mathematical foundation of analysis of the fluctuations in data of repeatedly measured line intensities is presented in detail. This method applied to data from various spectral lamps yields strong support for the new formula. By another more straightforward method, tabulated standard values of absolute intensities of a great number of spectral lines are shown to be in excellent agreement with the new formula. It is suggested that the two methods of analysis can be useful in spectrochemical research for identification of spectral lines and determination of atomic transition rates. The significance of the new formula is discussed in view of Planck's blackbody radiation law.
Treatment of Noise in Magnitude-Mode FT-ICR Spectra
Authors: Dunbar Robert C.
Published: July 2005

In FT-ICR spectroscopy it is often desirable to be able to determine ion abundances from the heights of small spectral peaks in the presence of substantial noise. When magnitude-mode transforms are used, the noise gives an apparent baseline shift, and it may be thought appropriate to measure peak heights from this apparent baseline. It is shown here that such a noise correction procedure is inappropriate, and that the peak heights measured from the original, noise-free baseline to the tops of the smoothed peaks give an excellent approximation to the true peak heights. Correction factors for peaks heights are given, which become significant at signal-to-noise ratios below about 3 and which may be useful when spectral accumulation is performed in the frequency domain.
Flow-Injection Inductively Coupled Plasma Atomic Emission Spectrometry with a Multielement Photodiode-Array Spectrometer
Authors: Brushwyler K. R. , Carter L. D. , Hieftje G. M.
Published: July 2005

A multichannel photodiode-array spectrometer was used to monitor the transient multielement atomic-emission signal generated by an inductively coupled plasma utilizing flow-injection sample introduction. The linearity, dynamic range, sensitivity, and precision of the technique were assessed for three different sample-loop volumes (110,290, and 500 µL). With a fixed, optimized integration time, a linear dynamic range of 3.5 orders of magnitude was established for five elements—Cd, Cr, Cu, Mg, and Zn—when the 290- and 500- µL sample loops were used. Because the lateral dispersion of the transient sample plug was low and because efforts were made to optimize the signal-to-background ratio by synchronizing the integration period of the photodiode-array detector with the transient signal, detection limits for the flow-injection system were comparable with those obtained with the use of continuous-nebulization sample introduction. An interface is described which enables temporal synchronization of the transient flow-injection signal with the signal integration period of the photodiode array.
Determination of Thallium, Manganese, and Lead in Food and Agricultural Standard Reference Materials by Electrothermal Atomizer Laser-Excited Atomic Fluorescence and Atomic Absorption Spectrometry with Slurry Sampling
Authors: Butcher David J. , Irwin Richard L. , Takahashi Junichi , Su Guizhen , Wei Guor-Tzo , Michel Robert G.
Published: July 2005

Electrothermal atomizer laser-excited atomic fluorescence spectrometry (ETA LEAFS) and electrothermal atomic absorption spectrometry (ETA AAS) have been compared for the determination of three elements in National Institute of Standards and Technology food and agricultural standard reference materials with dissolved and slurried samples. Advantages of slurry sampling include reduced sample preparation and a reduced risk of contamination. ETA LEAFS is an extremely sensitive technique, with detection limits one to four orders of magnitude more sensitive than ETA AAS. Using the front-surface illumination approach, this paper reports the first application of a modern, unmodified graphite tube furnace for the determination of manganese, thallium, and lead in biological materials by ETA LEAFS. Thallium was determined by ETA LEAFS at levels one to two orders of magnitude below the ETA AAS detection limit. The determinations done by ETA LEAFS with the use of either dissolved or slurry sampling agreed well with the certified values, with typical analytical RSDs between 3 and 10%. These precisions were similar to the precisions of the ETA AAS measurements. For ETA AAS, the sizes of the background signals reported in the literature are often about the same order of magnitude as the analytical signal. In this work, the sizes of the background signals for ETA LEAFS were shown to be negligible relative to the fluorescence signals for most samples investigated. The relatively small size for the ETA LEAFS background signals, when compared to ETA AAS background signals, indicates that background correction errors are less likely, and that stringent specifications might be unnecessary for ETA LEAFS background correction instrumentation.
Improved Chromatographic Resolution for Gas Chromatography/Matrix Isolation Infrared Spectroscopy
Authors: Klawun Christoph , Sasaki Tania A. , Wilkins Charles L. , Carter David , Dent Geoffrey , Jackson Peter , Chalmers John
Published: July 2005

When gas chromatography/matrix isolation infrared spectroscopy (GCV MI-IR) is carried out with a fixed cryodisk rotation speed, chromatographic resolution may be substantially degraded. In this research, an approach allowing dynamic programming of disk rotation speed is shown to result in much improved resolution in reconstructed chromatograms. Use of up to 254 different speeds during a single chromatographic run is possible. Thus, the analyst can match the requirements of any specific separation problem with an appropriate set of cryocollector movement speeds. As a consequence, much improved analytical performance without loss of sensitivity is possible for mixture analysis by GC/MI-IR, as is up to 30% higher apparent chromatographic resolution than is observed with a flame ionization detector. In addition, careful matching of sample spot size and detector area with the appropriate cryodisk speed leads to the detection of as little as 40 picograms of hexachlorobenzene.
Determination of Cholesterol Using a Novel Magnetohydrodynamic Acoustic-Resonance Near-IR (MARNIR) Spectrometer
Authors: Buice Robert G. , Lodder Robert A.
Published: July 2005

Near-IR spectrometric determination of minor constituents of biological systems is complicated by the fact that near-IR spectra of these materials vary in different chemical and physical environments. In such cases, wavelength selection methods and full-spectral techniques such as partial least-squares and principal component regression (which weight each wavelength in calibration) produce excess error because they must attempt to model both variations in major constituents and variations in the analyte. A magnetohydrodynamic acoustic-resonance near-IR (MARNIR) spectrometer can determine major constituents of biological materials noninvasively and nondestructively, leaving the near-IR spectrum of the analyte to be used quantitatively with less prediction error.
Evaluation of a Demountable Tangential Flow Torch for Microwave-Induced Plasma Atomic Emission Spectrometry
Authors: McCleary K. A. , Ducatte G. R. , Renfro D. H. , Long G. L.
Published: July 2005

A demountable torch for the microwave-induced plasma that utilizes a tangential flow pattern is described. This new torch is compared to a conventional all-quartz design in a series of comparative studies. Diagnostic studies consist of measurements of electron number densities, excitation temperatures, and ionization temperatures of an argon plasma generated in each torch. Hydrodynamic flow measurements, vertical emission profiles, and limits of detection provide further contrast between the characteristics of the demountable design and conventional all-quartz torch. The compatibility of the new torch design with supercritical CO, flows is demonstrated where the MIP is coupled with a packed-column supercritical fluid chromatograph for the purpose of element-specific detection. The physical advantages of the demountable torch over the all-quartz design are discussed.
Analysis of the Overlapping Bands in UV-Vis Absorption Spectroscopy
Authors: Antonov Liudmil , Stoyanov Stefan
Published: July 2005

The analysis of the overlapped bands in UV-Vis absorption spectroscopy provides valuable information about the structure of the molecule and its environment. The resolution of individual bands in the UV-Vis region is a complicated task since the absorption bands are generally strongly overlapped, they have different half-band widths, and their number is difficult to estimate. In the present study the possibilities of using Levenberg's method for analysis of overlapping bands in UV-Vis spectroscopy are discussed, and a logical algorithm for their resolution is developed. This approach is applied to the analysis of the vibrational structured long-wavelength bands of trans-stilbene and its derivatives.
Wavelength Calibration Methods for Low-Resolution Photodiode Array Spectrometers
Authors: Brownrigg J. Thomas
Published: July 2005

A wavelength calibration method for low-resolution diode array spectrometers is described. The method was developed for routine calibration of 0.1-meter-focal-distance spectrometers having 35- or 38-element silicon diode arrays, normally operated in the 340–700 nm spectral range. Each diode of the array is approximately 1 mm wide, giving an instrumental bandwidth of ∼10 nm per diode. The calibration method requires two well-separated monochromatic spectral lines, their central image locations on the array, and the grating groove frequency. This method is compared with nonlinear regression (least-squares) methods, with multiple calibration lines fitted to quadratic or cubic polynomials. The predictive accuracy of the wavelength-pair method compares favorably with the regression methods. A calibration accuracy of ∼±1 nm is expected for the instruments considered here. The method described could, in principle, be applied to instruments with higher resolution, such as those having self-scanned photodiode arrays with 25-μm or 50-μm-wide pixels. For such instruments, however, a large number of calibration lines should be resolved. In this case, the regression method, which averages diode position measurement errors, is probably more accurate. The wavelength-pair method is most useful for low-resolution instruments, for which regression methods may not be practical.
Pressure-Tuning FT-IR Study of Human Cervical Tissues
Authors: Wong Patrick T. T. , Wong Rita K. , Fung Michael Fung Kee
Published: July 2005

Infrared spectra of the normal connective, the normal epithelial, and the malignant epithelial tissues of cervix from seven patients have been measured as a function of pressure. Extremely high quality spectra of these tissue samples have been obtained. Consequently, structural differences at the molecular level among these three types of cervical tissues have been extracted from their pressure-tuning infrared spectra in the regions of the symmetric and antisymmetric stretching modes of phosphodiester groups, the C-O stretching mode, the CH2 bending mode, and the amide I mode. Significant differences in many features between the infrared spectra of the normal and the malignant cervical tissues and cells suggest that the infrared spectra of exfoliated cells and the biopsy of cervical tissues may be used in rapid evaluation of cervical cancer or in screening of large-volume normal cervical specimens. The infrared spectrum of the normal connective tissue of cervix in the frequency region 950 to 1100 cm−1 is similar to that of the malignant cervical tissue and cells. Therefore, if only this region of the spectrum is examined, the normal connective tissue will be misinterpreted as malignant tissue. However, the normal connective tissue can be differentiated unambiguously from the malignant tissue or the normal epithelial tissue by the infrared spectra in the frequency region 1200 to 1500 cm−1, where several well-defined sharp bands are unique for the normal connective tissue.
Multichannel Fourier Transform Spectroscopy Using Two-Dimensional Detection of the Interferogram and its Application to Raman Spectroscopy
Authors: Takahashi Satoshi , Ahn Jeung Sun , Asaka Shuji , Kitagawa Teizo
Published: July 2005

A system for multichannel Fourier transform spectroscopy was constructed by using a CCD detector and an interferometer consisting of Savart plate held between two polarizers, and practical problems associated with its application to Raman experiments were investigated. The novel idea of the present system lies in avoiding the aliasing distortion, seen in the spectrum measured with a one-dimensional multichannel detector, by arranging the principal axis of the sensitized plane of the CCD detector so that it is not coincident with the direction of the fringe pattern of the interferogram. The observed interferogram suffered geometrical distortion due to incompleteness of the Savart plate. In order to circumvent this problem, an algorithm for correcting this distortion by referring to the interferogram of appropriate monochromatic light was successfully developed. The resolution of a Raman spectrum obtained for indene was ∼40 cm−1, in agreement with the theoretical value expected for this system.
Infrared Intensities of Liquids XII: Accurate Optical Constants and Molar Absorption Coefficients between 6225 and 500 cm−1 of Benzene at 25°C, from Spectra Recorded in Several Laboratories
Authors: Bertie John E. , Jones R. Norman , Keefe C. Dale
Published: July 2005

This paper presents the results of a study to obtain accurate infrared absorption intensities of liquid benzene at 25°C. To achieve this we have determined the agreement between the intensities measured by different spectroscopists using the same instrument in the same laboratory and also by different spectroscopists in different laboratories using instruments made by different manufacturers. The agreement between integrated intensities over specific wavenumber ranges has been found to average about 2%. The spectra from the different laboratories have been averaged, unweighted, to give intensity spectra of benzene that are presented as the best available. The use of data from different instruments in different laboratories has reduced the influence of systematic instrumental errors, so that the agreement presented should be a better approximation to the accuracy of the intensities than would be the case from an extensive study by one person on one instrument. The intensity data presented agree with the only measurements that have been made against a primary standard, the evaluated uncertainty of which is about 6%. The results are presented in both graphic and tabular forms as spectra of the molar absorption coefficient, Em(ν˜), (also called the molar absorptivity, ε, formerly the extinction coefficient) and the real and imaginary refractive indices, n(ν˜) and k(ν˜), between 6225 and 500 cm−1. The peak heights and the areas under the bands in the imaginary refractive index spectrum are reported, together with the peak heights and the areas under the bands in the molar absorption coefficient spectrum. Imaginary refractive index, k(ν˜), and molar absorption coefficient, Em(ν˜), values are believed accurate to an average ±2% at the peaks of stronger bands, ±3.5% at the peaks of the weaker bands below 4100 cm−1, and ±2.5% above 4100 cm−1. The baseline k(ν˜) values are accurate to ∼10% above 1200 cm−1 and 1% to 5% below 1200 cm−1. The areas under bands or band groups in k(ν˜) and Em(ν˜) spectra are accurate to 2% on average, or 1.5% when measured above a baseline for calibration purposes. The real refractive index, n(ν˜), values are believed accurate to 0.2%.
Structural Transitions and pH-Dependent Equilibria between Unusual Double and Triple Helical Conformations of Nucleic Acid Polymers, Studied by UV Resonance Raman Spectroscopy
Authors: Gfrörer A. , Schnetter M. E. , Wolfrum J. , Greulich K. O.
Published: July 2005

In order to study pH-driven associations and equilibria between nucleic acid helices containing the homopolymers poly(A) and poly(U), the pH-value of solutions of poly(A) or poly(A)*poly(U) or the triple helix poly(U)*poly(A)*poly(U) was varied in steps of 0.5 pH units between pH = 7.0 and pH = 2.5. Resonance Raman spectra were taken with 260-nm and 220-nm excitation, both in H2O and in D2O solvent. For the solutions containing poly(A) only, marked spectral changes between pH = 6.0 and pH = 5.5 can be attributed to the formation of the parallel stranded double helix poly(A)+*poly(A)+. The cooperativity of this duplex formation is better represented in the 260-nm than in the 220-nm excitation spectra. The double helix poly(A)*poly(U) remains stable down to pH = 5.0. At pH = 4.5 and 4.0, the experimental spectra can be understood by means of a superposition of the spectra of the triple helix poly(U)*poly(A)*poly(U) and the protonated double helix poly(A)+*poly(A)+. The triple helix itself is stable at these pH values, as can be concluded from the spectra of solutions of this polymer. Below pH = 4.0, the spectra can be calculated by the sum of poly(A)+*poly(A)+ and the single-stranded poly(U) polymer. All the helical transitions observed are better represented in the spectra excited with 260 nm, whereas the protonation state is better resolved in the 220-nm spectra. The data reported here provide a basis for further studies of unusual nucleic acid structures as triple and quadruple helices and they show that UV-resonance Raman spectroscopy is a sensitive tool for studying the kinetics and dynamics of the formation of these structures.
Noninvasive Blood Glucose Assay by Near-Infrared Diffuse Reflectance Spectroscopy of the Human Inner Lip
Authors: Marbach R. , Koschinsky Th. , Gries F. A. , Heise H. M.
Published: July 2005

Near-infrared (NIR) spectra of the human inner lip were obtained by using a special optimized accessory for diffuse reflectance measurements. The partial-least squares (PLS) multivariate calibration algorithm was applied for linear regression of the spectral data between 9000 and 5500 cm−1 (Λ = 1.1–1.8 μm) against blood glucose concentrations determined by a standard clinical enzymatic method. Calibration experiments with a single person were carried out under varying conditions, as well as with a population of 133 different patients, with capillary and venous blood glucose concentration values provided. A genuine correlation between the blood glucose concentrations and the NIR-spectra can be proven. A time lag of about 10 min for the glucose concentration in the spectroscopically probed tissue volume vs. the capillary concentration can be estimated. Mean-square prediction errors obtained by cross-validation were in the range of 45 to 55 mg/dL. An analysis of different variance factors showed that the major contribution to the average prediction uncertainty was due to the reduced measurement reproducibility, i.e., variations in lip position and contact pressure. The results demonstrate the feasibility of using diffuse reflectance NIR-spectroscopy for the noninvasive measurement of blood glucose.
Use of Cassegrain System for in Situ Raman Scattering Study of Cyanide Ions on a Palladium Electrode
Authors: Seki Hajime , Samant Mahesh G.
Published: July 2005

The nonenhanced Raman scattering spectra from CN ions adsorbed at the electrolyte/Pd electrode interface has been obtained with the use of a combination of a Cassegrain lens and a multichannel detector. Previously reported FT-IR spectra under similar conditions were used to help interpret the Raman-scattering results. The scattering results are explained on the basis of five bands assigned to the CN stretches. The position of these bands at 1950, 2060, 2090, 2150, and 2220 cm−1 are assigned to the covalent bond to a bridge site, covalent bond to an atop site, and ionic bond to Pd, Pd(CN)42−, and Pd(CN)2. This study shows that it is possible to obtain an enhancement of about 103 by use of the Cassegrain system described here.
Determination of Methanol and Methyl tert-Butyl Ether in Gasoline by Infrared Spectroscopy Using the CIRCLE® Cell and Multivariate Calibration
Authors: Garcia Francisco X. , De Lima Lola , Medina Julio C.
Published: July 2005

The feasibility of predicting concentrations of methanol and methyl tert-butyl ether (MTBE) in gasolines from the mid-infrared absorption spectra was investigated. The C-O bond stretching band region was related to these oxygenated compounds' levels with the aid of multivariate statistics. The sample spectra were taken with the use of a circular internal reflectance (CIRCLE®) cell. With the use of partial least-squares (PLS) regression a model with 18 samples was built and used to predict a set of 10 gasolines with good agreement. Two additional samples prepared with other brands of gasoline were analyzed with the same model and no matrix effects were found.
Raman Spectra of 6LiRbSO4 and 7LiRbSO4
Authors: Oh Kyung Hui , Cho Joon Hyung , Kim Seung-Bin
Published: July 2005

The polarized Raman spectra of single-crystal 6LiRbSO4 and 7LiRbSO4 at room temperature are reported. On the basis of these data, symmetry-based band assignments are given for both internal and external optic modes. The translational optic modes of the lithium ion appear in the region between 444 and 364 cm−1. Vibrational coupling interactions are noted between the sulfate ion ν2 and the lithium translational optic modes in the same irreducible representation. Coupling interactions are negligible or small in 7LiRbSO4, while in 6LiRbSO4 the lithium isotope effect shifts the lithium translational modes into more coupling interaction with the sulfate ion ν2 modes.
Imaging of the Fluorescence Created by Ablation of Y2O3, BaO2, CuO, and YBa2Cu3O7–x by 308-nm Laser Light
Authors: Fried Daniel , Reck Gene P. , Kushida Toshimoto , Kim Gyung-Soo , Rothe Erhard W.
Published: July 2005

A gated intensified CCD camera is used to acquire time-resolved images of the plume generated from the excimer laser ablation of CuO, BaO2, Y2O3, and YBa2Cu3O7– x pellets in vacuum, He, or O2. Narrow (12-nm FWHM) bandpass filters are used to select emission from individual species within the plume. The spatial and the temporal evolution of the emission is unique for each of the ejected ions, atoms, and diatomics. A luminous shock front, i.e., a blast wave, is observed at pressures greater than 1 Torr in He and 0.1 Torr in O2. The propagation of this shock front is suitably described by scaling factors that were previously developed to describe the shock waves from a point explosion. Images of emission from atomic Cu and O were acquired after the ablation of CuO. These images imply that ion/electron bombardment is significant within the plasma plume. The time dependence of the images shows the evolution of the shock wave and suggests the origin of the luminous plume.
Nerve Growth Factor and its Precursor Differentially Regulate Hair Cycle Progression in Mice
Authors: Peters Eva M.J. , Hendrix Sven , Gölz Greta , Klapp Burghard F. , Arck Petra C. , Paus Ralf
Published: July 2005

Nerve growth factor (NGF) promotes proliferation via its high affinity receptor (TrkA). Its precursor proNGF promotes apoptosis via the pan-neurotrophin-receptor p75. Recently, we have identified NGF and p75 as important hair growth terminators. However, if proNGF is involved or if NGF can also promote hair growth via TrkA is unclear. By RT-PCR we found that NGF/proNGF mRNA levels peak during early anagen in murine back skin, whereas NGF/proNGF protein levels peak during catagen, indicating high turnover in early anagen and protein accumulation in catagen. By immunohistochemistry, NGF and TrkA are found in the proliferating compartments of the epidermis and hair follicle throughout the cycle. In contrast, strong proNGF is found in the highly differentiated inner root sheath and adjacent to the p75+ regressing epithelial strand in catagen. Commercial 7S NGF, which contains both NGF and proNGF, promotes anagen development in organ-cultured early anagen mouse skin, whereas it promotes catagen development in late anagen skin. Together, our findings suggest an anagen-promoting or anagen-supporting role for NGF/TrkA, and a catagen-promoting role for proNGF/p75 interactions. This has important implications for the future design of specific neurotrophin receptor ligands as novel pharmaceuticals in the modification of tissue remodeling processes such as hair growth or wound healing.
Trypanosoma cruzi Modulates the Expression of Rabs and Alters the Endocytosis in Mouse Cardiomyocytes In Vitro
Authors: Batista Denise G.J. , Silva Cristiane F. , Mota Renata A. , Costa Lilian C. , Meirelles Maria N.L. , Meuser-Batista Marcelo , Soeiro Maria N.C.
Published: July 2005

Chagas disease is an incurable illness caused by the protozoan Trypanosoma cruzi. Cardiomyocytes represent important targets for the parasite infection and alterations in their physiology were reported. Because endocytosis is involved in different cellular events and guanosine triphosphatase (GTPase) Rab proteins play important roles in various aspects of the membrane traffic, our aim was to characterize the expression of Rab proteins in T. cruzi-infected cardiomyocytes, which displayed a downregulation of Rab7 and Rab11, whereas the expression of Rab5a was maintained in the infected cultures even after longer periods of parasite internalization, but early endosome antigen 1 was partially downregulated. The parasite infection also decreased the uptake of fluid phase ligands by the cardiac cultures. The regulation of GTPase proteins and effector molecules can contribute to the altered physiology of the host cells by modifying the normal incoming of nutrients as well as interfering with other important events related to the endocytic pathway.
Developmental and Regional Expression and Localization of mRNAs Encoding Proteins Involved in RNA Translocation
Authors: Islam Shabana , Montgomery Robert K. , Fialkovich John J. , Grand Richard J.
Published: July 2005

RNA localization is a regulated component of gene expression of fundamental importance in development and differentiation. Several RNA binding proteins involved in RNA localization during development in Drosophila have been identified, of which Y14, Mago, Pumilio, and IMP-1 are known to be expressed in adult mammalian intestine. The present study was undertaken to define the developmental and regional expression of these proteins, as well as Staufen-1, in mouse intestinal cells and in other tissues and cell lines using RT-PCR, and localization using in situ hybridization and immunohistochemistry. Staufen-1, Y14, Mago-m, and Pumilio-1 were expressed in intestinal epithelial cells of both villus and crypt and in Caco-2 and IEC-6 cells. In contrast, expression of IMP-1 was age- and region-specific, showing clear expression in distal fetal and newborn intestine, but very low or no expression in adult. The mRNAs were cytosolic, with more apical than basal expression in enterocytes. Staufen protein showed a similar localization pattern to that of its cognate mRNA. Overall, the data suggest an essential role for these proteins in intestinal cells. Age and regional expression of IMP-1 may indicate a role in regulation of site-specific translation of intestinal genes or in RNA localization.
Immunohistochemistry in Human Placental Tissue—Pitfalls of Antigen Detection
Authors: Honig Arnd , Rieger Lorenz , Kapp Michaela , Dietl Johannes , Kämmerer Ulrike
Published: July 2005

Because incongruous controversial staining results are a common phenomenon in the placenta, methodical investigations are important to prevent researchers from obtaining misleading results. While investigating dendritic cells (DC) at the human fetomaternal interface, we observed staining of endothelial cells (EC) in chorionic villi for CD83. Given the high specificity of this antigen for DC, this did not seem credible. Previous studies had revealed the same surprising staining pattern with human leukocyte antigen (HLA)-G antibodies. We therefore analyzed human placental EC staining more closely. Both CD83 and HLA-G antibodies were of the same mouse IgG2b isotype. We also observed EC staining with a panel of control antibodies of the IgG2b isotype. This suggests a high affinity of human placental capillaries for mouse IgG2b. Several commonly used techniques for blocking nonspecific binding of antibodies could not prevent this nonspecific EC staining. A new preincubation step with purified human IgG was introduced. This abolished any placental EC staining with CD83, HLA-G, and IgG2b isotype control antibodies, presumably by blocking Fc receptors, whereas specific staining patterns remained unchanged. Mouse antibody of the IgG2b isotype are bound nonspecifically by vascular endothelial cells in human placenta and this can be overcome by blocking with purified human IgG. This blocking procedure could also be appropriate for frozen tissues other than placenta in which Fc receptors are expressed.
Mechanisms of Heat-induced Antigen Retrieval: Does pH or Ionic Strength of the Solution Play a Role for Refolding Antigens?
Authors: Emoto Katsura , Yamashita Shuji , Okada Yasunori
Published: July 2005

We investigated the effects of pH and ionic strength of solutions used for antigen retrieval to elucidate the mechanism of heat-induced antigen retrieval (HIAR) in immunohistochemistry. The immunostaining intensity of nuclear, cytoplasmic, cell membrane, and extracellular matrix antigens with 17 different antibodies was evaluated in formaldehyde-fixed and paraffin-embedded mouse and human tissues. Deparaffinized sections were autoclaved for 10 min in buffers with different pH values ranging from 3.0 to 10.5. To test the influence of ionic strength on immunoreactions, the sections were autoclaved for 10 min in 20 mM Tris-HCl buffers (TB) at pH 9.0 and 10.5 with or without 25, 50, and 100 mM NaCl. There were two immunostaining patterns for pH dependency of HIAR. First, the majority of antibodies recovered their antigenicity when heated in the buffers with both acidic pH (pH 3.0) and basic pH (pH 9.0 and 10.5). Second, some antibodies showed strong immunostaining only at basic pH values (pH 9.0 and 10.5). When the sections were autoclaved in TB at pH 9.0, immunostaining of all eight antibodies examined decreased as the NaCl concentration increased. On the other hand, when the sections were treated with TB at pH 10.5, all antibodies yielded stronger reactions in the buffer containing NaCl than in the buffer without NaCl; five antibodies exhibited the strongest immunoreaction at concentrations from 25 to 50 mM. These results suggest that the extended polypeptides by heating are charged negatively or positively at basic or acidic pH, and that an electrostatic repulsion force acts to prevent random entangling of polypeptides caused by hydrophobic attractive force and to expose antigenic determinants, during cooling process of HIAR solution.
An Alternative Pretreatment Procedure in Animal Transmissible Spongiform Encephalopathies Diagnosis Using PrPsc Immunohistochemistry
Authors: Bencsik Anna A. , Debeer Sabine O.S. , Baron Thierry G.M.
Published: July 2005

Because of its sensitivity, immunohistochemistry (IHC) of abnormal prion protein (PrPsc) is used more often in the diagnosis of transmissible spongiform encephalopathies (TSEs), such as scrapie and bovine spongiform encephalopathy (BSE). PrPsc IHC requires a combination of pretreatments (chemical, heating, and enzymatic). The method of application may depend on the anti-prion antibody considered. If these pretreatments are efficient for diagnostic purpose, it may, however, be interesting to use an alternative method to efficiently detect PrPsc IHC immunohistochemically using chemical pretreatments solely. Here we describe such pretreatments reporting the difficulty (section adhesion) but also the potential advantages of such methods (easy, quick, inexpensive, and amplifying effect).
Atomic Resolution Transmission Electron Microscopy of Surfaces
Authors: Chiaramonti Ann N. , Marks Laurence D.
Published: July 2005

A brief overview of transmission electron microscopy as it applies specifically to obtaining surface crystallographic information is presented. This review will encompass many of the practical aspects of obtaining surface crystal information from a transmission electron microscope, including equipment requirements, experimental techniques, sample preparation methods, data extraction and image processing, and complimentary techniques.
In situ Observation of Solid–liquid Interfaces by Transmission Electron Microscopy
Authors: Saka H. , Sasaki K. , Tsukimoto S. , Arai S.
Published: July 2005

Recent progress in in situ observation of solid–liquid interfaces by means of transmission electron microscopy, carried out by the Nagoya group, was reviewed. The results obtained on pure materials are discussed based on Jackson's theory. The structure of the solid–liquid interfaces of eutectic alloys was also observed. The in situ observation technique of solid–liquid interface is applied to industrially important reactions which include liquid phases.
Study of Deformation Behavior of Ultrafine-grained Materials Through in Situ Nanoindentation in a Transmission Electron Microscope
Authors: Jin M. , Minor A.M. , Ge D. , Morris J.W.
Published: July 2005

The mechanical properties of ultrafine-grained and nanograined materials have received a great deal of recent attention because of their unusual and promising values. However, some of the most important mechanisms of deformation remain unclear. In this work, the deformation behavior of ultrafine-grained Al films and ultrafine-grained Fe is studied through in situ nanoindentation in a transmission electron microscope. Deformation-induced coarsening by grain boundary migration was observed in the ultrafine-grained Al films during deformation at room temperature, whereas no grain boundary motion was found in ultrafine-grained Fe. The lack of grain boundary motion in Fe was attributed to the pinning effect of nano-sized particles at the Fe grain boundaries.
Thermal Stability of Atomic Layer Deposited Zr:Al Mixed Oxide Thin Films: An in Situ Transmission Electron Microscopy Study
Authors: Nistor L.C. , Richard O. , Zhao C. , Bender H. , Van Tendeloo G.
Published: July 2005

The thermal stability of amorphous Zr:Al mixed oxide films of different composition, produced on (001) silicon wafers by the atomic layer deposition method is studied by transmission electron microscopy during in situ heating experiments. The temperatures at which phase separation and crystallization occur are composition dependent. The crystallization of thick films (55–70 nm), deposited on HF-treated silicon surfaces covered with a 15 cycles Al2O3layer, results in the formation of cubic ZrO2and cubic γ–Al2O3. In very thin films (5 nm), deposited on silicon surfaces covered with a 0.5 nm SiO2thin film, the formation of tetragonal zirconium disilicide (ZrSi2) is observed in the microscope vacuum, at temperatures above 900 °C. This effect depends on the thickness of the as deposited thin film.
Transmission Electron Microscopy of Martensitic Transformation in Xe-implanted Austenitic 304 Stainless Steel
Authors: Xie Guoqiang , Song Minghui , Mitsuishi Kazutaka , Furuya Kazuo
Published: July 2005

Thin film specimens of austenitic 304 stainless steel implanted with 100 keV Xe ions at room temperature were investigated. Microstructural evolution and phase transformation were characterized and analyzed in situ with conventional and high-resolution transmission electron microscopy. The phase transformation in a sequence from austenitic γ face-centered cubic (fcc) to hexagonal close-packed (hcp), and then to a martensitic α body-centered cubic (bcc) structure was observed in the implanted specimens. The fraction of the induced α(bcc) phase increased with increasing Xe ion fluence. Orientation relationships between the induced α(bcc) phase and austenitic γ(fcc) matrix were determined to be (011)α//(111)γ and [111]α//[011]γ. The relationship was independent of the induced process of the martensitic phase transformation for austenitic 304 stainless steel specimen, in agreement with the Kurdjumov–Sachs (K-S) rule. It is suggested that the phase transformation is induced mainly by the formation of the highly pressurized Xe precipitates, which generate a large stress level in stainless steels.
In situ Tensile Testing of Nanoscale Freestanding Thin Films Inside a Transmission Electron Microscope
Authors: Haque M.A. , Saif M.T.A.
Published: July 2005

The unique capability of rendering opaque specimens transparent with atomic resolution makes transmission electron microscopy (TEM) an indispensable toolfor microstructural and crystallographic analysis of materials. Conventional TEM specimens are placed on grids about 3 mm in diameter and 10–100 μm thick. Such stringent size restriction has precluded mechanical testing inside the TEM chamber.So far, in situ testing of nanoscale thin foils has been mostly qualitative. Micro-electro-mechanical systems (MEMS) offer an unprecedented level of miniaturization to realize sensors and actuators that can add TEM visualization to nano-mechanical characterization. We present a MEMS-based uniaxial tensile experiment setup that integrates nanoscale freestanding specimens with force and displacement sensors, which can be accommodated by a conventional TEM straining stage. In situ TEM testing on 100-nm-thick freestanding aluminum specimens (with simultaneous stress measurement) show limited dislocation activity in the grain interior and consequent brittle mode of fracture. Plasticity at this size scale is contributed by grain boundary dislocations and partial dislocations.
Abnormal Lattice Expansion and Double Periodicity in La0.7Sr0.3MnO3 Thin Films Under Electron Irradiation
Authors: Zhang M. , Ma X.L. , Li D.X. , Lu H.B. , Chen Z.H. , Yang G.Z.
Published: July 2005

Perovskite-based SrNb0.2Ti0.8O3/La0.7Sr0.3MnO3 bilayer films were grown on (001) SrTiO3 substrate. By means of in situ transmission electron microscopy, lattice expansion and double periodicity were identified in both plan-view and cross-section La0.7Sr0.3MnO3 films under electron irradiation for 25 s. After the electron beam was removed from specimens, the original perovskite structure recovered within 10 min. However, when irradiation time was more than 1 min, the original perovskite structure could not recover and became an amorphous phase or a cavity created by irradiation. According to first-principle calculation and electron diffraction pattern simulation, formation mechanism of the lattice expansion and double periodicity is proposed based on oxygen deficiency during electron irradiation.
In situ High-resolution Electron Microscope Observation of Phase Change in Nanometer-sized Alloy Particles
Authors: Lee Jung-Goo , Mori Hirotaro , Yasuda Hidehiro
Published: July 2005

From the study of alloy phase formation in nanometer-sized particles by in situ transmission electron microscopy, it is revealed that not only the surface energy but also the interface energy of an interface between two different phases (solid–solid or solid–liquid) significantly changes the phase equilibrium of nanometer-sized particles. These energies result in large suppression of the eutectic point, structural instability, and unique solid/liquid two-phase structures in isolated nanometer-sized alloy particles. A theoretical study based on thermodynamics, which is modified in such a manner that Gibbs free energies for bulk materials were modified by taking factors affecting the phase equilibrium of nanometer-sized alloy particles into consideration, was proved useful to evaluate the results obtained from experiments.