bluuebunny/crossref_metadata_2025 huggingface dataset:
Existence of antimalarial formulations with low bioavailability in Tanzania
Authors: Minzi Omary M S , Massele Amosy , Justin-Temu Mary , Ericsson Örjan , Gustafsson Lars L
Published: April 2006

The main objective of this work was to assess the relative bioavailability of two tablet formulations containing sulfadoxine/pyrimethamine (SP) and marketed in Tanzania. Twelve healthy volunteers were randomized to receive a single oral dose of three SP tablets each containing 500 mg sulfadoxine (SDX) and 25 mg pyrimethamine (PYR) in a form of either A (a locally manufactured SP tablet formulation, manufactured by a local pharmaceutical industry in Tanzania) or B (Fansidar®, Hoffmann La Roche, Basel, Switzerland, an innovator's SP) after an overnight fasting. Serial blood samples (100 μL) were collected from a finger prick in duplicate up to 10 days and dried on Whatman® filter paper. The samples were assayed for SDX and PYR using high-performance liquid chromatographic methods. Pharmacokinetic parameters of SDX and PYR were estimated by single compartment method. The pharmacokinetics of formulation A - maximum plasma concentration, the areas under the plasma concentration - time curve and the relative bioavailability (A versus B) were significantly lower than those of formulation B ( P<0.1). These observed differences indicate bioinequivalence between the two products.
Does long-term chloramphenicol cause anaemia in Malawi?
Authors: Peek A C , Lavy C B D , Thyoka M , Pitani A
Published: April 2006

Common clinical practice in many tropical paediatric departments is that chloramphenicol courses are limited to 2 weeks due to concerns about anaemia. However, this approach is not supported by current research and animal models. We used chloramphenicol for 6 weeks in 146 children with septic arthritis. All the children improved clinically. Most children were anaemic on presentation (mean haemoglobin [Hb] 8.43 SD 1.9), but the anaemia improved rapidly with clinical resolution of the infection and was maintained at 6 months after presentation (mean Hb 10.57 SD 1.86).
Seroprevalence of human immunodeficiency virus among blood donors in Northwest Ethiopia, 1995-2002
Authors: Kassu Afework , Moges Feleke , Mekonnen Firew , Mengistu Getahun , Abate Ebba , Mekonnen Endris , Molla Kassie , Zewde Tessema , Aseffa Abraham , Wondmikun Yared , Ota Fusao
Published: April 2006

Data on age, sex, occupation, HIV serostatus and year of donation were collected from the blood donors log book of Gondar College of Medical Sciences Hospital, Northwest Ethiopia, for the period between January 1995 and December 2002 and analysed. The crude HIV seroprevalence was 9.9% (1109/11,204). A declining trend in the prevalence was observed from as high as 15.7% (207/1321) in 1995 to 9.3% (123/1327) in 1999 and down to 4.3% (68/1576) in 2002. The declining trend observed in recent years is encouraging and should further be strengthened by making use of the blood bank as an entry point for HIV testing and counselling services.
Spectrum of eye disorders among diabetes mellitus patients in Gaborone, Botswana
Authors: Mengesha Addisu Y
Published: April 2006

This cross-sectional study was designed to determine the spectrum and prevalence of eye disorders among diabetes mellitus (DM) patients in Gaborone, Botswana. All DM patients who attended Gaborone City Council (GCC) health facilities underwent eye examination at the specialist eye clinic. All of the study participants were interviewed using questionnaires and underwent laboratory investigations. A total of 401 DM patients participated in the study. About 60 % never had an eye examination before. Refractive error (29.2%) was the most prevalent followed by cataract (20.2%), retinopathy (9.2%), pterygeum (6.7%), glaucoma (2.5%) and keratopathy (0.7%). The study showed that DM patients are affected by many eye disorders other than diabetic retinopathy and regular eye examination should be part of diabetic care.
Sex Difference in the Antiplatelet Effect of Aspirin in Patients with Stroke
Authors: Cavallari Larisa H , Helgason Cathy M , Brace Larry D , Viana Marlos AG , Nutescu Edith A
Published: April 2006

Background:

There is substantial interpatient variability in response to aspirin after an ischemic stroke or transient ischemic attack (TIA), as assessed by ex vivo effects of aspirin on platelet aggregation. The factors contributing to this variability are not well defined.

Objective:

To determine whether demographic, social, or clinical characteristics are associated with ex vivo response to aspirin in patients with a history of stroke or TIA.

Methods:

Eighty-one patients who were taking aspirin for secondary stroke prevention and underwent ex vivo platelet aggregation studies were identified. The medical records of eligible patients were reviewed by clinicians who specialize in the management of stroke patients. Characteristics were compared between 45 patients who had a complete response to aspirin and 36 patients who exhibited an incomplete (partial) response to aspirin based on the results of platelet aggregation testing.

Results:

The median (range) aspirin dose was similar in complete (325; 81–1950 mg/day) and partial (325; 81–1300 mg/day) responders. There was no association between aspirin response and age, race, body mass index, medical history, smoking status, or use of statin or hormone replacement therapy. However, sex was significantly associated with response to aspirin, with more women in the partial versus complete responder group (75% vs 49%; p = 0.02).

Conclusions:

Our data suggest that aspirin may be less effective at inhibiting platelet aggregation in women compared with men who have a history of ischemic stroke or TIA.
Correlating Changes in Collagen Secondary Structure with Aging and Defective Type II Collagen by Raman Spectroscopy
Authors: Dehring Karen A. , Smukler Abigail R. , Roessler Blake J. , Morris Michael D.
Published: April 2006

A novel application of Raman spectroscopy for monitoring damage to ocular collagen in wild-type mice and Del1 (+/–) transgenic mice, a murine animal model of osteoarthritis, is described. In order to understand the progression of diseases of collagen, it is necessary to use methods that can recognize alterations in affected tissue due to chemical and/or genetic modifications. The heterozygous Del1 (+/–) transgenic mouse is established as a model for early-onset osteoarthritis caused by modifications to the type II collagen gene (COL2A1) that result in a truncated collagen fiber. We expect that abnormal type II collagen is expressed in articular cartilage and eye tissue of the Del1 (+/–) mouse. Eyes excised from a subset of specimens from another study using Del1 (+/–) mice were examined by Raman spectroscopy for evidence of defective collagen. Spectral contributions from the collagen protein were readily observed. The amide III envelope (1220–1280 cm−1) was used to characterize changes in collagen secondary structure. Raman spectra of the sclera component of eyes taken from transgenic and older wild-type mice show an increased collagen disorder, as expected. These preliminary results suggest that Raman is capable of recognizing and measuring abnormality in eye collagen and may have potential as a diagnostic tool for ocular collagen damage.
Comparison between Two Detection Systems for Fiber-Optic Chemical Sensor Applications
Authors: Yuan Shigui , DeGrandpre Michael
Published: April 2006

Two optical detection system designs are compared for fiber-optic chemical sensor applications. A single grating spectrograph with fiberoptic input and photodiodes at three different wavelengths is compared to 1 × 3 fiber-optic splitters and photodiode detectors with integrated interference filters. The splitters are used to direct the optical power to the filter photodiodes. Three types of 1 × 3 commercially available splitters were tested: a 400 μm fused glass fiber-optic coupler, a 1000 μm fused plastic fiber-optic coupler, and a 1000 μm glass fiber-optic bundle. This study finds that the fiber-splitter-based detection systems have similar stray light, signal-to-noise ratio, and long-term absorbance stability compared to the spectrograph detection system with a modest improvement in spectral resolution (from ∼12 nm to ∼6 nm). It is also much smaller in size and lower in cost. Applications of the two systems in a colorimetric CO2 partial pressure sensor are compared and similar accuracy and precision are achieved.
Analysis of Fiber Blends Using Horizontal Attenuated Total Reflection Fourier Transform Infrared and Discriminant Analysis
Authors: Espinoza Edgard , Przybyla Jennifer , Cox Robert
Published: April 2006

We have investigated the utility of a horizontal attenuated total reflection Fourier transform infrared spectrometer (HATR/FT-IR) for the analysis of fiber and textile blends. The identification of a blended textile can be accomplished by subtracting a reference spectrum of the textile's most abundant component, leading to a difference spectrum that infers the identity of the second constituent of the blended textile. Mathematical post-processing of the spectra employing discriminant analysis provided a useful statistical tool to confirm the fiber blend components.
Interference Effect of Iron on the Determination of Gold in Geological Samples Using the Vapor Generation Technique and Preconcentration in a Graphite Furnace
Authors: Ertaş Gülay , Ataman O. Yavuz
Published: April 2006

A vapor generation procedure for the production of volatile species of Au was studied using electrothermal atomic absorption spectrometry (ETAAS). The interference effects of iron in solution and in the gas phase in a quartz T-tube were studied for the first time in detail. A dual vapor generation system was used for a single heated quartz tube atomizer, so that it was possible to study interferences and classify them regarding their origins. Results show that both gas-phase and liquid-phase interferences are present. It was also concluded that since the total interference effect causes the Au signal to be lower as compared to only the presence of gas-phase interactions in the experiment, the net liquid-phase interference from Fe should be suppressed. The method described in this study was used for the determination of gold in an ore reference material, Carlin Ore Mine, for the purpose of demonstrating the ability of the reported method to determine Au without any extraction procedure.
Near-Infrared Combination and Overtone Bands of the CH2 Sequence in CH2X2, CH2XCHX2, and CH3(CH2)5CH3 and Their Characteristic Frequency Zones
Authors: Iwamoto Reikichi , Nara Akishi , Matsuda Toshihiko
Published: April 2006

We characterized near-infrared spectra of the CH2 sequence in CH2X2 (X = halogen), CH2ClCHCl2, and CH3(CH2)5CH3. Each near-infrared absorption in the region from 3500 to 10 000 cm−1 is consistently assigned to one of the five different combination or overtone groups, in the order of increasing frequency, of the {[v(CH)]+[δ(CH)]} (A), {[v(CH)]+[2δ(CH)]} (B), [2v(CH)] (C), {[2v(CH)]+[δ(CH)]} (D), and [3v(CH)] (E) types, where v(CH) and δ(CH) denote the CH stretching and CH deformation normal modes, respectively. Each group has its own characteristic frequency zone. The bands of B, D, and E, which are second-order combinations or overtones, are weaker by 1/10–1/50 than those of A and C, which are first-order combinations or overtones. The near-infrared spectra of the CH2 sequence show “window zones” of very weak or no absorptions. This suggests that we can perceive the characteristic near-infrared bands of a functional group through the window zones, and we give an example to demonstrate this. The first-order combination bands of type A only of CH2X2 are reasonably assigned to a pair of the normal modes of v(CH) and δ(CH). From this we predict that the first-order combination bands should give structural information on the CH2 chain, similar to the infrared fundamental bands.
Transformation of Time-Resolved Spectra to Lifetime-Resolved Spectra by Maximum Entropy Inversion of the Laplace Transform
Authors: Lórenz-Fonfría Víctor A. , Kandori Hideki
Published: April 2006

We present a method for the analysis of time-resolved spectroscopic data following first-order kinetics. The time traces at all the available spectroscopic channels (e.g., wavelength or wavenumber) are inverse Laplace transformed. The transformation is stabilized by the maximum entropy method generalized for solutions without sign-restriction. In this way, time-resolved spectra can be converted to lifetime-resolved spectra, where bands appear at coordinates corresponding to their spectroscopic maxima and time constant of appearance (negative amplitude) or disappearance (positive amplitude). From the lifetime-resolved spectra, the number of exponentially decaying components, their time constants, and their decay-associated spectra are readily available. Moreover, since bands are spread in two dimensions extra band-resolution is possible. We named this method of transforming time-resolved spectra into lifetime-resolved spectra multi-spectroscopic channel maximum entropy inversion of the Laplace transform (M-MaxEnt-iLT). The basis of M-MaxEnt-iLT is presented in detail and its properties and limitations are thoroughly discussed. We also show how the combination of M-MaxEnt-iLT with spectral smoothing or deconvolution can improve the appearance and/or band resolution of the obtained lifetime-resolved spectra.
Partial Least Squares Regression Calibration for Determining Wax Content in Processed Flax Fiber by Near-Infrared Spectroscopy
Authors: Sohn Miryeong , Himmelsbach David S. , Morrison W. Herbert , Akin Danny E. , Barton Franklin E.
Published: April 2006

The quality of flax fiber in the textile industry is closely related to the wax content remaining on the fiber after the cleaning process. Extraction by organic solvents, which is currently used for determining wax content, is very time consuming and produces chemical waste. In this study, near-infrared (NIR) spectroscopy was used as a rapid analytical technique to develop models for wax content associated with flax fiber. Calibration samples ( n = 11) were prepared by manually mixing dewaxed fiber and isolated wax to provide a range of wax content from 0 to 5%. A total of fourteen flax fiber samples obtained after a cleaning process were used for prediction. Principal component analysis demonstrated that one principal component is enough to separate the flax fibers by their wax content. The most highly correlated wavelengths were 2312, 2352, 1732, and 1766 nm, in order of significance. Partial least squares models were developed with various chemometric preprocessing approaches to obtain the best model performance. Two models, one using the entire region (1100–2498 nm) and the other using the selected wavelengths, were developed and the accuracies compared. For the model using the entire region, the correlation coefficient ( R2) between actual and predicted values was 0.996 and the standard error of prediction (RMSEP) was 0.289%. For the selected-wavelengths model, the R2 was 0.997 and RMSEP was 0.272%. The results suggested that NIR spectroscopy can be used to determine wax content in very clean flax fiber and that development of a low-cost device, using few wavelengths, should be possible.
Multispectral Polarization Imaging for Observing Blood Oxygen Saturation in Skin Tissue
Authors: Arimoto Hidenobu
Published: April 2006

We propose a new technique that combines two-dimensional (2D) multispectral imaging and polarization gating for observing the blood oxygen saturation (SpO2) level in human skin tissue. The spectral decomposition of the skin tissue image provides the principal information on blood oxygenation. The polarization gating selects the measurement depth according to the relative orientation of the two polarizers that are placed on a camera and a light source. The combination of these two methods yields multispectral images of the superficial and deep layers of the skin tissue separately. In order to evaluate the blood oxygen, we focus on the multispectral images of the deep site. The SpO2 levels at each image pixel are calculated by means of the partial least squares regression with respect to each reflectance spectrum. The reassignment of the predicted responses retrieves an image whose pixel values represent the relative SpO2 levels. A demonstration experiment for acquiring the multispectral polarization images is performed in the spectral range of 500 to 680 nm, and the SpO2 distributions are obtained.
Perturbation-Correlation Moving-Window Two-Dimensional Correlation Spectroscopy
Authors: Morita Shigeaki , Shinzawa Hideyuki , Noda Isao , Ozaki Yukihiro
Published: April 2006

A new method of analysis, perturbation-correlation moving-window two-dimensional (PCMW2D) correlation spectroscopy, is proposed. For a spectral data set collected under an external perturbation, this method provides a pair of synchronous and asynchronous two-dimensional correlation spectra plotted on a plane between a spectral variable (e.g., wavenumber) axis and a perturbation variable (e.g., temperature) axis. One of the advantages of this new correlation analysis method is that complicated spectral variation along the perturbation direction can be monitored. It has been found that the synchronous and asynchronous PCMW2D correlation spectra are similar to the first perturbation derivative and negative second perturbation derivative spectra of the original data, respectively. To demonstrate the potential of PCMW2D correlation spectroscopy, it has been applied to temperature-dependent infrared (IR) spectra of a poly(vinyl alcohol) (PVA) film. The thermal behavior of the PVA film has been revealed by the PCMW2D correlation analysis. Two characteristic cross-peaks are observed in the synchronous PCMW2D correlation spectra generated from the temperature-dependent IR spectra between the crystalline phase C–O stretching band at 1141 cm−1 and the melting temperature of 209 °C and between the amorphous phase C–O stretching band at 1095 cm−1 and another specific temperature of 233 °C. This specific temperature of 233 °C corresponds to the thermal degradation temperature due to the elimination of the hydroxyl group attached to the main chain.
Water Diffusion Behavior in Epoxy Resins with Various Fluorine Contents
Authors: Li Liang , Chen Yin , Li Shanjun
Published: April 2006

In this work, novolac resin with perfluorinated side chains was synthesized and cured with o-Cresol novolac epoxy resin to obtain epoxy resins with various fluorine contents. Attenuated total reflection Fourier transform infrared spectroscopy (ATR/FT-IR) was used to monitor the in situ water diffusion process in these systems. The diffusion coefficient of water first increased and then slightly decreased with increasing fluorine content, which could be attributed to two opposite effects induced by perfluorinated side chains: enhanced hydrophobicity and increased free volume. In addition, generalized two-dimensional (2D) correlation analysis was employed to investigate both the sorption and the desorption process of water diffusion, and two kinds of water molecules, named bound and free water, were found. It was interesting to find that in the sorption process, the change in the population of bound water molecules occurs earlier than the change in the population of free water molecules, while in the desorption process, the sequence was reversed.
Observation of Room-Temperature 5D1 Luminescence of an Organoeuropium Complex Encapsulated in Sol-Gel Glass
Authors: Zaitoun Mohammed
Published: April 2006

In comparing emissions of the inorganic Eu3+ salts (chloride or nitrate) to organoeuropium complexes doped into optically transparent sol-gel glass, previous studies have indicated that changes in the local chemical environment by chelation or variation of the ligand or gel matrix compositions were found to leave the main spectral features of Eu3+ essentially unchanged; complexation just increases the emission intensity of europium and leads to broadening and splitting of the peaks. In all cases studied and irrespective of the excitation energy, the observable emission peaks result only from relaxations out of the 5D0 excited state of Eu3+ to the first five levels of the 7F ground manifold. The present research examines the luminescence behavior of EuCl3 and Eu-TETA (TETA is the macro cycle, 1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetraaceticacid) doped into a sol-gel host; in addition to emissions from the 5D0, emission from the 5D1 excited state of Eu3+ is observed for the first time.
Near-Infrared Spectroscopic Determination of Salinity and Internal Pressure of Fluid Inclusions in Minerals
Authors: Kagi Hiroyuki , Kiyasu Akiko , Akagi Tasuku , Nara Masayuki , Sawaki Takayuki
Published: April 2006

A near-infrared (NIR) spectroscopic method is proposed to achieve the simultaneous determination of salinity and internal pressure of fluid inclusions in natural minerals. A combination band between the antisymmetric stretching and bending vibrations of molecular water at approximately 5180 cm−1 was observed for standard salt solutions and natural minerals containing fluid inclusions with known salinities. A curve-fitting procedure was used to analyze the change in the band shape of the combination. Justification of the calibration was confirmed by observation of fluid inclusions in natural minerals whose salinities had already been determined using microthermometry. The detection limit of the present method is 1 NaCl-eq wt. %. The minimum size of fluid inclusions that produced well-resolved spectra was approximately 30 μm. This method was applied to assess micro fluid inclusions in a natural diamond with cubic growth habit (cuboid). The salinity and residual pressure of those fluid inclusions were estimated respectively as 4.4 wt. % NaCl-eq and 0.6–0.8 GPa. The present method is complementary to Raman microscopy and microthermometry for the determination of salinity in fluid inclusions of geological samples.
Classification of Chemical and Biological Warfare Agent Simulants by Surface-Enhanced Raman Spectroscopy and Multivariate Statistical Techniques
Authors: Pearman William F. , Fountain Augustus W.
Published: April 2006

Initial results demonstrating the ability to classify surface-enhanced Raman (SERS) spectra of chemical and biological warfare agent simulants are presented. The spectra of two endospores ( B. subtilis and B. atrophaeus), two chemical agent simulants (dimethyl methylphosphonate (DMMP) and diethyl methylphosphonate (DEMP)), and two toxin simulants (ovalbumin and horseradish peroxidase) were studied on multiple substrates fabricated from colloidal gold adsorbed onto a silanized quartz surface. The use of principal component analysis (PCA) and hierarchical clustering were used to evaluate the efficacy of identifying potential threat agents from their spectra collected on a single substrate. The use of partial least squares–discriminate analysis (PLS-DA) and soft independent modeling of class analogies (SIMCA) on a compilation of data from separate substrates, fabricated under identical conditions, demonstrates both the feasibility and the limitations of this technique for the identification of known but previously unclassified spectra.
New Method for the Microscopic, Nondestructive Acquisition of Ultraviolet Resonance Raman Spectra from Plant Cell Walls
Authors: Czaja Andrew D. , Kudryavtsev Anatoliy B. , Schopf J. William
Published: April 2006

Raman spectroscopy has long been used for the chemical analysis of organic matter, including natural products, using excitation wavelengths in the visible, infrared, or ultraviolet portions of the spectrum. The use of ultraviolet resonance Raman spectroscopy (UVRR) to study bulk samples of plant tissue has typically been carried out by rotating homogeneous macro-samples beneath the laser beam in order to minimize the amount of UV radiation impinging on any one spot, thereby avoiding its potentially damaging effects on the organic matter analyzed. This paper extends the use of UVRR to the study on a microscopic scale of individual plant cell walls by use of the controlled micro-displacement of a sample.
Quantitative Analysis of Methyl Parathion Pesticides in a Polydimethylsiloxane Microfluidic Channel Using Confocal Surface-Enhanced Raman Spectroscopy
Authors: Lee Donghoon , Lee Sangyeop , Seong Gi Hun , Choo Jaebum , Lee Eun Kyu , Gweon Dae-Gab , Lee Sanghoon
Published: April 2006

A fast and ultra-sensitive trace analysis of methyl parathion pesticides in a polydimethylsiloxane (PDMS) microfluidic channel was investigated using confocal surface-enhanced Raman spectroscopy (SERS). A three-dimensional PDMS-based passive micromixer was fabricated for this purpose. This PDMS micromixer showed a high mixing efficiency because a strong chaotic advection was developed by the simultaneous vertical and transverse dispersion of the confluent streams. The confocal SERS signal was measured after methyl parathion pesticides were effectively adsorbed onto silver nanoparticles while flowing along the upper and lower alligator-teeth-shaped PDMS channel. A quantitative analysis of the methyl parathion pesticides was performed based on the measured peak height at 1246 cm−1. Our method has a detection limit of 0.1 ppm. This value satisfies the requirement recommended by the Collaborative International Pesticides Analytical Council (CIPAC) for the determination of methyl parathion in pesticide formulations. This study demonstrates the feasibility of using confocal SERS for the highly sensitive detection of methyl parathion pesticides in a PDMS microfluidic channel.
New Methodology to Obtain a Calibration Model for Noninvasive Near-Infrared Blood Glucose Monitoring
Authors: Maruo Katsuhiko , Oota Tomohiro , Tsurugi Mitsuhiro , Nakagawa Takehiro , Arimoto Hidenobu , Tamura Mamoru , Ozaki Yukihiro , Yamada Yukio
Published: April 2006

This paper reports new methodology to obtain a calibration model for noninvasive blood glucose monitoring using diffuse reflectance near-infrared (NIR) spectroscopy. Conventional studies of noninvasive blood glucose monitoring with NIR spectroscopy use a calibration model developed by in vivo experimental data sets. In order to create a calibration model, we have used a numerical simulation of light propagation in skin tissue to obtain simulated NIR diffuse reflectance spectra. The numerical simulation method enables us to design parameters affecting the prediction of blood glucose levels and their variation ranges for a data set to create a calibration model using multivariate analysis without any in vivo experiments in advance. By designing the parameters and their variation ranges appropriately, we can prevent a calibration model from chance temporal correlations that are often observed in conventional studies using NIR spectroscopy. The calibration model (regression coefficient vector) obtained by the numerical simulation has a characteristic positive peak at the wavelength around 1600 nm. This characteristic feature of the regression coefficient vector is very similar to those obtained by our previous in vitro and in vivo experimental studies. This positive peak at around 1600 nm also corresponds to the characteristic absorption band of glucose. The present study has reinforced that the characteristic absorbance of glucose at around 1600 nm is useful to predict the blood glucose level by diffuse reflectance NIR spectroscopy. We have validated this new calibration methodology using in vivo experiments. As a result, we obtained a coefficient of determination, r2, of 0.87 and a standard error of prediction (SEP) of 12.3 mg/dL between the predicted blood glucose levels and the reference blood glucose levels for all the experiments we have conducted. These results of in vivo experiments indicate that if the parameters and their vibration ranges are appropriately taken into account in a numerical simulation, the new calibration methodology provides us with a very good calibration model that can predict blood glucose levels with small errors without conducting any experiments in advance to create a calibration model for each individual patient. This new calibration methodology using numerical simulation has promising potential for NIR spectroscopy, especially for noninvasive blood glucose monitoring.
Temperature-Jump Apparatus with Raman Detection Based on a Solid-State Tunable (1.80–2.05 μm) kHz Optical Parametric Oscillator Laser
Authors: Balakrishnan Gurusamy , Hu Ying , Spiro Thomas G.
Published: April 2006

The operating characteristics of a pulsed (10 ns) tunable near-infrared (NIR) laser source are described for temperature-jump (T-jump) applications. A Q-switched Nd:YLF laser (∼10 ns pulses) with a 1 kHz repetition rate is used to pump a potassium titanyl arsenate (KTA) crystal-based optical parametric oscillator (OPO), producing ∼1 mJ NIR pulses that are tunable (1.80–2.05 μm) across the 1.9 μm vibrational overtone band of water. This T-jump source has been coupled to a deep ultraviolet (UV) probe laser for Raman studies of protein dynamics. T-jumps of up to 30 °C, as measured via the O–H stretching Raman band of water, are readily achieved. Application to cytochrome c unfolding is demonstrated.
Vibrational Circular Dichroism of Matrix-Assisted Amino Acid Films in the Mid-Infrared Region
Authors: Zhang Peng , Polavarapu Prasad L.
Published: April 2006

Vibrational circular dichroism (VCD) spectra in the mid-infrared region of amino acid films are reported here for the first time. Amino acid films are formed from aqueous solutions with α-cyclodextrin (CD) serving as the matrix to facilitate the film formation. This film method eliminates the strong interfering water absorption seen in the solution study and makes it easier to measure the VCD in the 1800–1200 cm−1 region. VCD spectra for films of six amino acids, L-alanine, L-proline, L-methionine, L-histidine, L-phenylalanine, and L-tryptophan, are obtained. For amino acids with low solubility (L-phenylalanine and L-tryptophan), VCD could not be measured in solution, so the film method is the only means of obtaining the VCD spectra for such amino acids. For amino acids with moderate solubility (L-alanine, L-proline, L-methionine, and L-histidine), VCD spectra are also obtained in the solution state and compared with their corresponding spectra in the film state. A good correlation is found between the film and solution spectra for both absorption and VCD. The VCD spectra of L-methionine, L-histidine, L-phenylalanine, and L-tryptophan are reported here in the mid-infrared region for the first time. The present study broadens the application range of the VCD technique and enhances its role in the detection and analysis of biologically important compounds.
Analysis of Error in Pavement Ground Truth Indicators for Evaluating the Accuracy of Automated Image Collection and Analysis System
Authors: Lee H , Kim J
Published: April 2006

The main purpose of this paper is to present the Automated Image Collection System (AICS) and Manual Image Analysis System (MIAS) as “ground-truth” for evaluating Automated Image Collection System (AICS) and Automated Image Analysis System (AIAS) for highway asset management. The proposed “ground-truth” is evaluated with respect to its repeatability against a traditional “ground-truth” procedure based on Manual Distress Collection System (MDCS) and Manual Distress Analysis System (MDAS). To capture digital images automatically, a vehicle mounted with a digital video camera was driven on the pavement test section. To determine the repeatability of MIAS, the images were evaluated by three individuals twice per individual. To determine the repeatability of MDCS/MDAS, the same individuals were asked to evaluate the same pavement section in the field twice per individual. Repeatability on three crack types was evaluated for two survey methods and three individuals. Overall, the average relative precisions of AICS/MIAS-based procedure by three individuals were 10, 8, and 19 % for longitudinal, transverse, and block cracks, respectively, whereas those of MDCS/MDAS-based procedure were 43, 45, and 41 % for longitudinal, transverse, and block cracks, respectively. In conclusion, the proposed AICS/MIAS-based “ground-truth” measurements can be considered as more repeatable by human operators than MDCS/MDAS-based “ground-truth” measurements.
Ignition of a Composite Cylinder with Plastic Liner
Authors: Barthélémy H
Published: April 2006

An increasing number of composite cylinders are being used every year to store and transport compressed gases. These cylinders are very efficient, since a large quantity of gas can be transported at a relative low total weight compared to the traditional steel and aluminum cylinders. The most efficient composite cylinders are the cylinders that have plastic liners. The main applications are where the weight savings are important, such as cylinders for self-contained breathing apparatus (SCBA) used by firemen. In this paper, we describe an accident which occurred in France. A fireman was killed by the explosion of such a cylinder during use; the accident was attributed to the violent reaction of the oxygen (contained in the compressed air) with the plastic liner. In the paper, the ignition mechanisms are investigated and recommendations are provided to avoid any repetitions of such an accident.
On Piste Fatalities in Recreational Snow Sports in the U.S
Authors: Shealy JE , Johnson RJ , Ettlinger CF
Published: April 2006

This study documents fatalities and risk factors in alpine winter sports. The authors have tracked all known fatalities (n = 854) occurring to recreational skiers and snowboarders within the boundaries of ski resorts in the United States since January 1978 through the winter of 2004/05. Data are limited to trauma deaths. Medical emergency deaths, deaths to employees, and deaths involving uphill lift facilities were excluded. Fatality data came from three sources: the U.S. Consumer Product Safety Commission (CPSC), the National Ski Areas Association (NSAA), and public news sources. Information concerning the accident, the injury, and the equipment used, were recorded. Data on skier and snowboarder resort utilization and demographic variables were obtained from NSAA annual reports. This particular analysis covers the 14 seasons 1991/92 through 2004/05. Five hundred sixty-two deaths were recorded; 97 to snowboarders and 465 to skiers during 761 million resort visits. During that time, helmet utilization went from essentially zero to 33.2% for the general at-risk population. The fatality rate for skiers was 0.75 deaths per million visits (D/MV), and the snowboarder rate was 0.53 D/MV. These rates have not changed significantly over time. Most fatalities occurred to experienced males between the ages of 18 to 43. The most common scenario is a severe head injury resulting from high speed impact with a tree on or beside an intermediate trail. During the three most recent seasons, the known average prevalence of helmet utilization was 38.7% among the fatally injured. Helmet utilization does not appear to affect fatality incidence, but it does shift primary cause of death patterns, from mostly head injuries for those not using a helmet to mostly chest and torso for those wearing a helmet. The fatality rate for alpine skiers remained significantly higher than for snowboarders. The demographic profile of the fatally injured remained unchanged from previous research.
Micro-Plastic Material Model and Residual Fields in Rolling Contacts
Authors: Popescu G , Gabelli A , Espejel GM , Wemekamp B
Published: April 2006

This paper describes a model for the prediction of micro-plastic material transformation and associated residual stress field development in bearing steels during over-rolling. The high and mainly hydrostatic pressure field induced by the rolling element load, leads to the development of micro-plastic deformation in the subsurface layer of the rolling contact. The resulting plastic strain distribution gives rise to an associated self-equilibrating residual stress field that can be experimentally quantified using X-ray diffraction methods. A novel three-dimensional elastic-plastic over-rolling solution is used to evaluate the plastic strains and material transformation. Central to this plastic contact formulation is the incremental approach to deal with nonlinear material behavior. The Prandtl-Reuss constitutive equations in conjunction with Huber-Mises-Hencky yield criterion and Ramberg-Osgood strain-hardening relationships are applied to describe the plastic behavior of common hardened bearing steels. A nonlinear isotropic law is applied to describe the transformation of the retained austenite during stress cycles and changes in the strain-hardening behavior of the material microstructure. Application of this model with an incremental solution scheme based on the Conjugate Gradient Method (CGM) gives good convergence properties and fast solution for each cycle. Comparison between experimentally obtained residual stresses and stress fields derived from the present micro-plastic contact model, indicates good agreement. Numerical simulations, carried out to derive the maximum operating contact pressures in the elastic regime are also in agreement with published data. The model opens new possibilities in the evaluation of steels and heat treatments used in rolling bearings. Furthermore, this micro-plastic contact model may help the interpretation of the load history leading to a given pattern of residual stress measured in bearing rings.
Durability Test Analysis in a Passenger Vehicle Damper Spring Tower
Authors: Palma ES , Martins MGM
Published: April 2006

The current technology for durability qualification of the damper spring tower component of a passenger vehicle is presented. The methodology was based on durability experiments performed on actual components mounted on a vehicle. Stresses acting on the component were experimentally measured by using rosette strain gages. Durability tests were performed over two different public road surfaces. Fatigue damage assessment was performed and the life of the component was estimated.
Multi-Depth Deflectometer Dynamic Response Measurements under Simulated New Generation Aircraft Gear Loading
Authors: Gopalakrishnan K , Thompson MR , Manik A
Published: April 2006

In this paper, the comparative effect of dual-tridem (Boeing 777) and dual-tandem (Boeing 747) gear trafficking is studied on the Multi-Depth Deflectometer (MDD) responses of two medium-strength subgrade flexible test sections at the National Airport Pavement Test Facility (NAPTF). Using the MDD response-time histories and in-depth displacements obtained under repeated traffic loading, the results were investigated in terms of rebound (recovered) and residual (unrecovered) displacements in the pavement and in the subgrade. The resilient behavior of the NAPTF flexible pavement sections were characterized by analyzing the MDD rebound response data. The results showed that the rebound surface displacements were significantly influenced by changes in asphalt concrete surface layer temperature. Analysis of transverse distributions of MDD rebound surface displacements revealed multiple-wheel load interaction effects. In general both the rebound and residual (and hence the maximum total) displacements are approximately equivalent for both the dual-tridem and dual-tandem gears.
Rapid Taste Responses in the Gustatory Cortex during Licking
Authors: Stapleton Jennifer R. , Lavine Michael L. , Wolpert Robert L. , Nicolelis Miguel A. L. , Simon Sidney A.
Published: April 2006

Rapid tastant detection is necessary to prevent the ingestion of potentially poisonous compounds. Behavioral studies have shown that rats can identify tastants in ∼200 ms, although the electrophysiological correlates for fast tastant detection have not been identified. For this reason, we investigated whether neurons in the primary gustatory cortex (GC), a cortical area necessary for tastant identification and discrimination, contain sufficient information in a single lick cycle, or ∼150 ms, to distinguish between tastants at different concentrations. This was achieved by recording neural activity in GC while rats licked four times without a liquid reward, and then, on the fifth lick, received a tastant (FR5 schedule). We found that 34% (61 of 178) of GC units were chemosensitive. The remaining neurons were activated during some phase of the licking cycle, discriminated between reinforced and unreinforced licks, or processed task-related information. Chemosensory neurons exhibited a latency of 70–120 ms depending on concentration, and a temporally precise phasic response that returned to baseline in tens of milliseconds. Tastant-responsive neurons were broadly tuned and responded to increasing tastant concentrations by either increasing or decreasing their firing rates. In addition, some responses were only evoked at intermediate tastant concentrations. In summary, these results suggest that the gustatory cortex is capable of processing multimodal information on a rapid timescale and provide the physiological basis by which animals may discriminate between tastants during a single lick cycle.
Estrogen Induces Estrogen Receptor α-Dependent cAMP Response Element-Binding Protein Phosphorylation via Mitogen Activated Protein Kinase Pathway in Basal Forebrain Cholinergic NeuronsIn Vivo
Authors: Szegő Éva M. , Barabás Klaudia , Balog Júlia , Szilágyi Nóra , Korach Kenneth S. , Juhász Gábor , Ábrahám István M.
Published: April 2006

In addition to classical genomic mechanisms, estrogen also exerts nonclassical effects via a signal transduction system on neurons. To study whether estrogen has a nonclassical effect on basal forebrain cholinergic system, we measured the intensity of cAMP response element-binding protein (CREB) phosphorylation (pCREB) in cholinergic neurons after administration of 17β-estradiol to ovariectomized (OVX) mice. A significant time-dependent increase in the number of pCREB-positive cholinergic cells was detected after estrogen administration in the medial septum-diagonal band (MS-DB) and the substantia innominata (SI). The increase was first observed 15 min after estrogen administration. The role of classical estrogen receptors (ERs) was evaluated using ER knock-out micein vivo. The estrogen-induced CREB phosphorylation in cholinergic neurons was present in ERβ knock-out mice but completely absent in ERα knock-out mice in MS-DB and SI. A series ofin vitrostudies demonstrated that estrogen acted directly on cholinergic neurons. Selective blockade of the mitogen activated protein kinase (MAPK) pathwayin vivocompletely prevented estrogen-induced CREB phosphorylation in cholinergic neurons in MS-DB and SI. In contrast, blockade of protein kinase A (PKA) was effective only in SI. Finally, studies in intact female mice revealed levels of CREB phosphorylation within cholinergic neurons that were similar to those of estrogen-treated OVX mice. These observations demonstrate an ERα-mediated nonclassical effect of estrogen on the cholinergic neurons and that these actions are present under physiological conditions. They also reveal the role of MAPK and PKA–MAPK pathway activation in nonclassical estrogen signaling in the basal forebrain cholinergic neuronsin vivo.
Separation of μ-Opioid Receptor Desensitization and Internalization: Endogenous Receptors in Primary Neuronal Cultures
Authors: Arttamangkul Seksiri , Torrecilla Maria , Kobayashi Kazuto , Okano Hideyuki , Williams John T.
Published: April 2006

A close relationship between desensitization and internalization of μ-opioid receptors (MORs) has been proposed based on differential actions of series of agonists. The role that these two processes have in the development of tolerance and dependence to opioids has been a controversial subject that has been studied in a variety of model systems. Here, we examine desensitization and internalization of endogenous MORs simultaneously in primary cultures of locus ceruleus neurons using fluorescently tagged peptide agonists. With the use of two fluorescent opioid peptides, dermorphin-Bodipy Texas Red and dermorphin-Alexa594 (Derm-A594), desensitization was measured electrophysiologically and trafficking was followed by the accumulation of intracellular fluorescent puncta. Blocking endocytosis with concanavalin A eliminated the accumulation of fluorescent puncta but desensitization induced by Derm-A594 was unaffected. Likewise, after treatment with concanavalin A, there was no change in either desensitization or recovery from desensitization induced by [Met]5enkephalin. The results demonstrate that desensitization and the recovery from desensitization are not dependent on receptor internalization and suggest that the activity of endogenous MORs in primary neurons can be modulated at the level of the plasma membrane.
Brain-Derived Neurotrophic Factor Is Critically Involved in Thermal-Experience-Dependent Developmental Plasticity
Authors: Katz Adi , Meiri Noam
Published: April 2006

All species exhibit critical period for sensory development, yet very little is known about the molecules involved in the changes in the network wiring that underlies this process. Here the role of brain-derived neurotrophic factor (BDNF) in the critical period of thermal control establishment in chicks was investigated.

Neuroanatomically, the body temperature is balanced by the preoptic anterior hypothalamus (PO/AH) and controlled by thermosensitive neurons. Exposure to hot or cold conditions during the critical period of temperature control development causes a plastic change in the ratio between heat- and cold-sensitive cells and can modulate temperature tolerance.

It was found that expression of BDNF mRNA but not of NGF or neurotrophin-3 was induced in the PO/AH of 3-d-old chicks during both heat and cold exposure. The peak of BDNF induction in both heat and cold exposure occurred after 6 h, with, respectively, threefold and sevenfold increases in its mRNA expression.

To prove the concept that BDNF activation is a critical step in thermal-experience-dependent plasticity, BDNF was “knocked down” using antisense. It was found that, when BDNF in the PO/AH was inhibited by 80% during the third postnatal day, thermal establishment was impaired, and, after 1 week, the chicks’ body temperature was reduced by 0.5°C. Furthermore, later in life, their reaction to thermal challenge was altered, and they exhibited a pronounced reduction in their ability to maintain their body temperature and body weight under harsh conditions. Together, these results prove that BDNF is critically involved in thermal-experience-dependent development.