bluuebunny/crossref_metadata_2025 huggingface dataset:
Silver-Coated Zeolite Crystal Films as Surface-Enhanced Raman Scattering Substrates
Authors: Yan Wenfu , Bao Lili , Mahurin Shannon M. , Dai Sheng
Published: April 2004

Silver-coated zeolite A and zeolite NaX crystal films prepared by vacuum deposition were investigated as surface-enhanced Raman scattering (SERS) substrates. The substrates were active for the enhancement of Raman scattering from uranyl ions. A detection limit of 10−5 M for uranyl was obtained using silver-coated zeolite A films. One advantage of these zeolite-based substrates is that the negatively charged microporous framework provides the selectivity for adsorption based on static electric charges. The SERS effects of positively charged uranyl ions and neutrally charged benzoic acid were compared. For the zeolite A substrate, there was a 100-times-greater sensitivity.
Analysis of 1H/2H Exchange Kinetics Using Model Infrared Spectra
Authors: Raussens Vincent , Ruysschaert Jean-Marie , Goormaghtigh Erik
Published: April 2004

This paper investigates the different approaches that best retrieve band shape parameters and kinetic time constants from series of protein Fourier transform infrared (FT-IR) spectra recorded in the course of 1H/2H exchange. In this first approach, synthetic spectra were used. It is shown that 1H/2H exchange kinetic measurements can help resolve spectral features otherwise hidden because of the overlap of various spectral contributions. We evaluated the efficiency of Fourier self-deconvolution, synchronous/asynchronous correlation, difference spectroscopy, principal component analysis, inverse Laplace transform, and determination of the underlying spectra by global analysis assuming first-order kinetics with either known or unknown time constants. It is demonstrated that some strategies allow the extraction of both the time dependence and the spectral shape of the underlying contributions.
Influence of the Laser Pulse Duration on Spectrochemical Analysis of Solids by Laser-Induced Plasma Spectroscopy
Authors: Le Drogoff B. , Chaker M. , Margot J. , Sabsabi M. , Barthélemy O. , Johnston T. W. , Laville S. , Vidal F.
Published: April 2004

Quantitative analysis of aluminum and copper alloys by means of laser-induced plasma spectroscopy (LIPS) has been investigated for three representative laser pulse durations (80 fs, 2 ps, and 270 ps). The experiments were carried out in air at atmospheric pressure with a constant energy density of 20 J/cm2. Because the decay rate of the spectral emission depends on the laser pulse duration, the optimum detection requires an optimization of the temporal gating acquisition parameters. LIPS calibration (sensitivity and nonlinearity) and the limit of detection (LOD) are discussed in detail. While the LOD of minor elements embedded in alloy samples obtained by sub-picosecond or sub-nanosecond laser pulses are both time and element dependent, provided an appropriate temporal window is chosen, the optimum LODs (several parts per million (ppm)) prove to be independent of the laser pulse duration. Finally, it is found that for elements such as those detected here, gated LIPS spectra using picosecond or sub-picosecond laser pulses provide much better LOD values than non-gated spectra.
Residual Stress Mapping of Epoxy Molding Compound in a Ball Grid Array Microelectronic Package Using a Fluorescent Sensor
Authors: Muraki Naoki , Matoba Nobuhiro , Hirano Takayuki , Yoshikawa Masanobu , Pezzotti Giuseppe
Published: April 2004

Thermal residual stresses developed at the time of semiconductor molding may cause serious problems both in their structural and functional performance; therefore, residual stress assessment in microelectronic devices is a mandatory evaluation step. Fluorescence piezo-spectroscopy was applied to evaluate residual stresses with a microscopic resolution inside a semiconductor encapsulant. In order to obtain reliable stress information, a low fraction of alumina powder, as a fluorescent sensor, was embedded into the silica/epoxy molding compound. Residual stress was transferred from the molding compound to the alumina phase and could be monitored by recording the shift of the sharp and intense fluorescence spectrum of Cr3+ in alumina. Two-dimensional residual-stress maps, recorded near the edge of the silicon chip, revealed a strong stress concentration in the molding compound. Experimental results were compared with calculations obtained by the linear finite element method. Such a comparison showed that the experimental stress values were systematically larger than the corresponding calculated values due to local delamination at the chip edge.
Dual Beam Light Profile Microscopy: A New Technique for Optical Absorption Depth Profilometry
Authors: Power J. F. , Fu S. W.
Published: April 2004

Light profile microscopy† (LPM) is a recently developed technique of optical inspection that is used to record micrometer-scale images of thin-film cross-sections on a direct basis. In single beam mode, LPM provides image contrast based on luminescence, elastic, and/or inelastic scatter. However, LPM may also be used to depth profile the optical absorption coefficient of a thin film based on a method of dual beam irradiation presented in this work. The method uses a pair of collimated laser beams to consecutively irradiate a film from two opposing directions along the depth axis. An average profile of the beam's light intensity variation through the material is recovered for each direction and used to compute a depth-dependent differential absorbance profile. This latter quantity is shown from theory to be related to the film's depth-dependent optical absorption coefficient through a simple linear model that may be inverted by standard methods of numerical linear algebra. The inverse problem is relatively well posed, showing good immunity to data errors. This profilometry method is experimentally applied to a set of well-characterized materials with known absorption properties over a scale of tens of micrometers, and the reconstructed absorption profiles were found to be highly consistent with the reference data.
Corroded Surface Roughness of Copper Analyzed by Fourier Transform Infrared Mapping Microscopy and Optical Profilometric Study
Authors: Kasperek J. , Lefez B. , Beucher E.
Published: April 2004

This study shows the effects of roughness on infrared spectra shapes of thin corrosion products on metallic substrates. The calculated spectra show that the baseline is mainly affected by increasing roughness and that such effects do not shift the position of the absorption bands. The model obtained has been used to extract data of artificial patina on a copper surface. Surface defects of copper substrates can be distinguished on the whole surface, from the morphological and chemical points of view, using optical profilometry and infrared microspectroscopy. An homogeneous layer of cuprite covers the surface except in the linear defects. Fourier transform infrared (FT-IR) analysis indicates that a mixture of atacamite and clinoatacamite is mainly located in these scratchs. The width of these particular areas is in good agreement with profilometric observations.
Determination of Uronic Acids in Isolated Hemicelluloses from Kenaf Using Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) and the Curve-Fitting Deconvolution Method
Authors: Batsoulis A. N. , Nacos M. K. , Pappas C. S. , Tarantilis P. A. , Mavromoustakos T. , Polissiou M. G.
Published: April 2004

Hemicellulose samples were isolated from kenaf ( Hibiscus cannabinus L.). Hemicellulosic fractions usually contain a variable percentage of uronic acids. The uronic acid content (expressed in polygalacturonic acid) of the isolated hemicelluloses was determined by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and the curve-fitting deconvolution method. A linear relationship between uronic acids content and the sum of the peak areas at 1745, 1715, and 1600 cm−1 was established with a high correlation coefficient (0.98). The deconvolution analysis using the curve-fitting method allowed the elimination of spectral interferences from other cell wall components. The above method was compared with an established spectrophotometric method and was found equivalent for accuracy and repeatability ( t-test, F-test). This method is applicable in analysis of natural or synthetic mixtures and/or crude substances. The proposed method is simple, rapid, and nondestructive for the samples.
Identification of Sporulated and Vegetative Bacteria Using Statistical Analysis of Fourier Transform Mid-Infrared Transmission Data
Authors: Foster Nancy S. , Thompson Sandra E. , Valentine Nancy B. , Amonette James E. , Johnson Timothy J.
Published: April 2004

A combined mid-infrared spectroscopic/statistical modeling approach for the discrimination and identification, at the strain level, of both sporulated and vegetative bacterial samples is presented. Transmission mode spectra of bacteria dried on ZnSe windows were collected using a Fourier transform mid-infrared (FT-IR) spectrometer. Five Bacillus bacterial strains ( B. atrophaeus 49337, B. globigii Dugway, B. thuringiensis spp. kurstaki 35866, B. subtilis 49760, and B. subtilis 6051) were used to construct a reference spectral library and to parameterize a four-step statistical model for the systematic identification of bacteria. The statistical methods used in this initial feasibility study included principal component analysis (PCA), classification and regression trees (CART), andMahalanobis distance calculations. Internal cross-validation studies successfully classified 100% of the samples into their correct physiological state (sporulated or vegetative) and identified 67% of the samples correctly as to their bacterial strain. Analysis of thirteen blind samples, which included reference and other bacteria, nonbiological materials, and mixtures of both nonbiological and bacterial samples, yielded comparable accuracy. The primary advantage of this approach is the accurate identification of unknown bacteria, including spores, in a matter of minutes.
Raman Spectroscopic Analysis of Cyanogenic Glucosides in Plants: Development of a Flow Injection Surface-Enhanced Raman Scatter (FI-SERS) Method for Determination of Cyanide
Authors: Thygesen Lisbeth Garbrecht , Jørgensen Kirsten , Møller Birger Lindberg , Engelsen Søren Balling
Published: April 2004

Cyanogenic glucosides were studied using Raman spectroscopy. Spectra of the crystal forms of linamarin, linustatin, neolinustatin, amygdalin, sambunigrin, and dhurrin were obtained using a Raman spectrograph microscope equipped with a 532 nm laser. The position of the signal from the C=N triple bond of the cyanohydrin group was influenced by the nature of the side group and was above 2240 cm−1 for the three cyanogenic glucosides that contain a neighboring aromatic ring, and below or partially below 2240 cm−1 for the non-aromatic cyanoglucosides. Signals from the CN bond of linamarin/lotaustralin in leaves and roots from a medium cyanogenic cassava variety were obtained in situ using a Fourier transform near-infrared (FT-NIR) Raman interferometer with a 1064 nm laser, but the signal was very weak and difficult to obtain. A spectrum containing a signal from the CN bond of dhurrin in a freeze-dried sorghum leaf was also obtained using this instrument. Surface-enhanced Raman Spectroscopy (SERS) was demonstrated to be a more sensitive method that enabled determination of the cyanogenic potential of plant tissue. The SERS method was optimized by flow injection (FI) using a colloidal gold dispersion as effluent. Potential problems and pitfalls of the method are discussed.
Deep-Ultraviolet Raman Microspectroscopy: Characterization of Wide-Gap Semiconductors
Authors: Nakashima Shin-Ichi , Okumura Hazime , Yamamoto Taketsugu , Shimidzu Ryosuke
Published: April 2004

We have developed a high-throughput deep-ultraviolet (DUV) Raman microspectrometer with excitation from a continuous wave (cw) laser operated at 244 nm that enables us to characterize thin surface layers of wide-gap semiconductors. This spectrometer system consists of a filter spectrometer for the rejection of stray light and a high-dispersion spectrograph combined with a liquid nitrogen cooled charge-coupled device (CCD) detector and extends the low-frequency limit of the observable spectral range down to 170 cm−1. In the microscope we use a Cassegrain reflective objective for the collection of the scattered light and an off-axis mirror for introduction of the excitation laser light. DUV Raman spectroscopy has been applied for studying wide-gap semiconductors including SiC and AlGaN epitaxial films and shallow implanted layers of these materials. Raman spectra of various crystals have also been measured for examining the performance of this system. Resonance enhancement of Raman bands has been observed for several semiconductors, and the results are discussed.
Polarization Spectroscopy Applied to the Detection of Trace Constituents in Sooting Combustion
Authors: Walewski J. W. , Nyholm K. , Dreizler A. , Aldén M.
Published: April 2004

The potential of polarization spectroscopy for the detection of trace constituents in sooting combustion was investigated. It was demonstrated that the directionality of the polarization spectroscopy signal can be exploited to efficiently suppress incoherent interferences, e.g., Rayleigh scattering at soot particles. We also show how polarization spectroscopy compares with laser-induced fluorescence in this type of environment by applying both techniques to atmospheric-pressure, premixed propane/oxygen flames. The acquired signals were spatially resolved along the centerline of the flame, and measurements were conducted at several heights above the burner head and for medium to very high fuel-to-oxidizer ratios. Through our work we found that polarization spectroscopy can be applied even in the presence of large soot fractions. For most conditions, where laser-induced fluorescence suffered from interferences like elastic scattering, spatially filtered polarization spectroscopy signals were virtually background-free, and only for high soot loads did a noticeable background on the latter signal appear. This background likely stems from Mie scattering at very large soot particles.
Light Emission Diode Water Thermometer: A Low-Cost and Noninvasive Strategy for Monitoring Temperature in Aqueous Solutions
Authors: Thompson Sebastián A. , Andrade Francisco J. , Iñón Fernando A.
Published: April 2004

A spectroscopic device for monitoring the temperature of aqueous solutions is presented. It uses a 950 nm light emission diode as light source and two photodiodes as detectors. Temperature is monitored following the thermally induced absorbance changes of the water–OH second overtone (∼960 nm). A linear response between the light absorbed by an aqueous solution and its temperature is found in the range from 15 to 95 °C. A prediction error of 0.1 °C and a precision of 0.07 °C in temperature measurement can be achieved. Up to 0.1 M of electrolyte concentration can be present in the solution without significantly affecting the temperature measurement. Different strategies, such as remote (noninvasive) or in situ (using a fiber-optic probe) temperature measurement, are shown, and their relative advantages are discussed.
Ultrasensitive Detection of 1, 4-Bis(4-Vinylpyridyl)Phenylene in a Small Volume of Low Refractive Index Liquid by Surface-Enhanced Raman Scattering-Active Light Waveguide
Authors: Xu Weiqing , Xu Shuping , Lü Zhicheng , Chen Lei , Zhao Bing , Ozaki Yukihiro
Published: April 2004

This paper reports a novel surface-enhanced Raman scattering (SERS)-active light waveguide method for ultrasensitive detection of a sample dissolved in a small volume of low refractive index liquid. The SERS-active light waveguide demonstrated in this study was constructed via the light-guiding silica capillary. The surface of its inner wall was modified with SERS-active silver nanoparticles that can remarkably enhance Raman signals. The capillary with the SERS-active modified layer was filled with the sample solution to form the SERS-active liquid core (LC) fiber. The incident laser beam travels through the waveguide in a totally reflective mode within the fiber wall and penetrates a small distance into the sample solution by the evanescent wave field. The Raman scattering of the analytes adsorbed onto the surface of the SERS-active modified layer can be excited by laser beam and refracted into the fiber wall. Thus, a sample dissolved in low refractive index liquid, e.g., methanol, can be quantitatively monitored by Raman spectroscopy and the detection limit of its concentration is lower than 10−9 mol/L.
Digital Filtering Implementations for the Detection of Broad Spectral Features by Direct Analysis of Passive Fourier Transform Infrared Interferograms
Authors: Tarumi Toshiyasu , Small Gary W. , Combs Roger J. , Kroutil Robert T.
Published: April 2004

Finite impulse response (FIR) filters and finite impulse response matrix (FIRM) filters are evaluated for use in the detection of volatile organic compounds with wide spectral bands by direct analysis of interferogram data obtained from passive Fourier transform infrared (FT-IR) measurements. Short segments of filtered interferogram points are classified by support vector machines (SVMs) to implement the automated detection of heated plumes of the target analyte, ethanol. The interferograms employed in this study were acquired with a downward-looking passive FT-IR spectrometer mounted on a fixed-wing aircraft. Classifiers are trained with data collected on the ground and subsequently used for the airborne detection. The success of the automated detection depends on the effective removal of background contributions from the interferogram segments. Removing the background signature is complicated when the analyte spectral bands are broad because there is significant overlap between the interferogram representations of the analyte and background. Methods to implement the FIR and FIRM filters while excluding background contributions are explored in this work. When properly optimized, both filtering procedures provide satisfactory classification results for the airborne data. Missed detection rates of 8% or smaller for ethanol and false positive rates of at most 0.8% are realized. The optimization of filter design parameters, the starting interferogram point for filtering, and the length of the interferogram segments used in the pattern recognition is discussed.
Rho Kinase Regulates Schwann Cell Myelination and Formation of Associated Axonal Domains
Authors: Melendez-Vasquez Carmen V. , Einheber Steven , Salzer James L.
Published: April 2004

The myelin sheath forms by the spiral wrapping of a glial membrane around an axon. The mechanisms involved are poorly understood but are likely to involve coordinated changes in the glial cell cytoskeleton. Because of its key role as a regulator of the cytoskeleton, we investigated the role of Rho kinase (ROCK), a major downstream effector of Rho, in Schwann cell morphology, differentiation, and myelination. Pharmacologic inhibition of ROCK activity results in loss of microvilli and stress fibers in Schwann cell cultures and strikingly aberrant myelination in Schwann cell-neuron cocultures; there was no effect on Schwann cell proliferation or differentiation. Treated Schwann cells branch aberrantly and form multiple, small, independent myelin segments along the length of axons, each with associated nodes and paranodes. This organization partially resembles myelin formed by oligodendrocytes rather than the single long myelin sheath characteristic of Schwann cells. ROCK regulates myosin light chain phosphorylation, which is robustly, but transiently, activated at the onset of myelination. These results support a key role of Rho through its effector ROCK in coordinating the movement of the glial membrane around the axon at the onset of myelination via regulation of myosin phosphorylation and actomyosin assembly. They also indicate that the molecular machinery that promotes the wrapping of the glial membrane sheath around the axon is distributed along the entire length of the internode.
Dual Neuroprotective Signaling Mediated by Downregulating Two Distinct Phosphatase Activities of PTEN
Authors: Ning Ke , Pei Lin , Liao Mingxia , Liu Baosong , Zhang Yunzhou , Jiang Wen , Mielke John G. , Li Lei , Chen Yonghong , El-Hayek Youssef H. , Fehlings Michael G. , Zhang Xia , Liu Fang , Eubanks James , Wan Qi
Published: April 2004

The tumor suppressor PTEN (phosphatase and tensin homolog deleted on chromosome 10) is a lipid and protein phosphatase. We report here that PTEN physically associates with the NR1 and NR2B subunits of NMDA receptors (NMDARs) in rat hippocampus. Downregulating the protein expression of PTEN inhibits the function of extrasynaptic NMDARs and decreases NMDAR surface expression, suggesting a crucial role for endogenous PTEN in the modulation of NMDAR-mediated neuronal function. Reducing PTEN expression also enhances Akt/Bad phosphorylation in hippocampal neurons. Importantly, suppressing lipid and protein phosphatase activity of PTEN, respectively, activates Akt and inhibits extrasynaptic NMDAR activity and thereby protects against ischemic neuronal deathin vitroandin vivo. Thus, our study reveals a dual neuroprotective mechanism by which Akt/Bad and extrasynaptic NMDARs are regulated via downregulation of two distinct PTEN phosphatase activities and present the possibility of PTEN as a potential therapeutic target for stroke treatment.
A Bioinformatics Analysis of Memory Consolidation Reveals Involvement of the Transcription Factor c-Rel
Authors: Levenson Jonathan M. , Choi Sangdun , Lee Sun-Young , Cao Yun Anna , Ahn Hyung Jin , Worley Kim C. , Pizzi Marina , Liou Hsiou-Chi , Sweatt J. David
Published: April 2004

Consolidation of long-term memory (LTM) is a complex process requiring synthesis of new mRNAs and proteins. Many studies have characterized the requirement forde novomRNA and protein synthesis; however, few studies have comprehensively identified genes regulated during LTM consolidation. We show that consolidation of long-term contextual memory in the hippocampus triggers altered expression of numerous genes encompassing many aspects of neuronal function. Like contextual memory formation, this altered gene expression required NMDA receptor activation and was specific for situations in which the animal formed an association between a physical context and a sensory stimulus. Using a bioinformatics approach, we found that regulatory elements for several transcription factors are over-represented in the upstream region of genes regulated during consolidation of LTM. Using a knock-out mouse, we found thatc-rel, one of the transcription factors identified in our bioinformatics study, is necessary for hippocampus-dependent long-term memory formation.
Exact determination of Indium incorporation in (In
x
Ga1–

x
N/GaN)-multiple quantum well structures by X-ray diffraction and -reflectivity and its impact on optical properties
Authors: Schulze Fabian , Bläsing Jürgen , Dadgar Armin , Krost Alois
Published: April 2004

We studied the structural and optical properties of In
x
Ga1–

x
N/GaN multiple quantum wells (MQWs) on Si(111) grown by metal organic vapor phase epitaxy by means of photoluminescence, X-ray reflectometry (XRR), and high resolution X-ray diffractometry (HRXRD). The combination of both X-ray analysis methods allows a very precise determination of the structural parameters of the layer systems. In particular, the Indium incorporation and the well thickness of the optically active layers were investigated. Thus, in dependence on crystallographic quality and thicknesses, their error bars of determined values could be reduced to an accuracy of lower than 0.2 nm of well thickness and Δx = 0.02 of Indium proportion. By growing systematic series with various MOVPE deposition temperatures and times the correlations to the optical properties were determined.
X-ray and VIS light scattering from light-induced polymer gratings
Authors: Henneberg Oliver , Panzner Tobias , Pietsch Ullrich , Geue Thomas , Saphiannikova Marina , Rochon Paul , Finkelstein Ken
Published: April 2004

Sinusoidally shaped surface relief gratings made of polymer films containing azobenzene moieties can be created by holographic illumination with laser light of about λ ≈ 500 nm. The remarkable material transport takes place at temperatures far (100 K) below the glass transition temperature of the material. As probed by visible light scattering the efficiency of grating formation crucially depends on the polarization state of the laser light and is maximal when circular polarization is used. In contrast to VIS light scattering X-ray diffraction is most sensitive for periodic surface undulations with amplitudes below 10 nm. Thus, combined in-situ X-ray and visible light scattering at CHESS were used to investigate the dynamics of surface relief grating formations upon laser illumination. The time development of grating peaks up to 9th order at laser power of P = 20 mW/cm2 could be investigated, even the onset of grating formation as a function of light polarization. A linear growth of grating amplitude was observed for all polarizations. The growth velocity is maximal using circularly polarized light but very small for s-polarized light.
Regulation of Glucose Metabolism in the Liver
Authors: Newgard Christopher B.
Published: April 2004

The liver plays a critical role in control of glucose homeostasis via its dual capacities for glucose disposal and glucose production. This chapter provides a review of the mechanisms by which key pathways of glucose metabolism are regulated in liver. This includes a detailed discussion of glycolysis, gluconeogenesis, glycogen metabolism, and glucose transport, and changes in activity of these pathways in response to changes in nutritional status and in diabetes. The advent of modern molecular biology and genetics has resulted in many fresh insights into new regulatory proteins and transcription factors that influence key steps of hepatic glucose metabolism, as well as a new appreciation for the importance of spatial organization and compartmentalization in control of flux through the relevant pathways. These new findings are highlighted and integrated with the large body of prior knowledge in the field.
New Drugs for the Treatment of Diabetes Mellitus
Authors: Bailey Clifford J.
Published: April 2004

This chapter reviews agents other than insulin that are being considered or recently introduced for the treatment of hyperglycemia. These include agents that lower blood glucose by delaying the intestinal digestion and absorption of carbohydrates, increase insulin concentrations, or potentiate insulin action. Other agents under investigation act independently of insulin to enhance glucose utilization, reduce glucose production, decrease obesity, or increase glucose elimination. Intestinal carbohydrate digestion is delayed by fiber supplements and by agents that competitively inhibit α‐glucosidase enzymes (e.g., miglitol and voglibose), thereby decreasing postprandial glucose excursions. Several insulin secretagogues have been designed to rapidly and transiently close ATP‐sensitive potassium channels in the pancreatic B‐cells (e.g., novel meglitinides and imidazolines). Analogues of the intestinal incretin glucagon‐like peptide 1 (GLP‐1) (7‐36 amide), which are more stable and longer acting than the native peptide, act predominantly via the cAMP pathway within the B‐cells to potentiate nutrient‐induced insulin secretion, and enhance insulin biosynthesis. Additionally these agents delay gastric emptying, promote satiety, and, most interestingly, appear to increase formation of new B‐cells. Inhibitors of the circulating enzyme dipeptidyl peptidase 4 augment the effects of GLP‐1 by slowing the degradation of GLP‐1. Non‐peptide compounds have been identified that can activate insulin receptor signaling and prevent normal deactivation of insulin receptor signaling (e.g., inhibitors of certain protein tyrosine phosphatases). Several new thiazolidinedione and non‐thiazolidinedione peroxisome proliferator‐activated receptor‐γ (PPAR‐γ) agonists are in development, along with dual PPAR‐γ and ‐α agonists to address both hyperglycemia and dyslipidemia. Various anti‐obesity agents have been shown to benefit glycemic control, including new β3‐adrenoceptor agonists to stimulate thermogenesis. The amylin analogue pramlintide, which acts centrally to reduce appetite, suppress glucagon secretion, and slow gastric emptying offers an adjunct to insulin therapy, without causing weight gain. Further agents are being considered to antagonize glucagon receptors, reduce the metabolic effects of glucocorticoids, and directly stimulate glucose uptake and metabolism by muscle. Approaches to reduce hepatic glucose output include compounds that inhibit glycogen phosphorylase, glucose‐6‐phosphatase, or other enzymes of gluconeogenesis. Increased glucose elimination is being considered by inhibiting renal glucose reabsorption.
Effective Insulin Therapy
Authors: Bergenstal Richard M.
Published: April 2004

Effective insulin therapy begins with an understanding of the clinically effective time actions of the insulin preparations available today. Rapid and long acting insulin analogues have been a great advance in the management of both type 1 and type 2 diabetes by improving glucose control and flexibility in schedules while minimizing hypoglycemia. Insulin is a key therapy often under‐utilized in type 2 diabetes. The barriers to initiating insulin in type 2 diabetes must be understood and overcome. A systematic approach to insulin therapy, which emphasizes the importance of patient self‐management and the use of team care, enhances the prospect of achieving optimal glucose control while maintaining a flexible and high‐quality lifestyle for each individual with diabetes.
High‐temperature kinetics of the homogeneous reverse water–gas shift reaction
Authors: Bustamante F. , Enick R. M. , Cugini A.V. , Killmeyer R. P. , Howard B. H. , Rothenberger K. S. , Ciocco M. V. , Morreale B. D. , Chattopadhyay S. , Shi S.
Published: April 2004

The high‐temperature rate of reaction of the homogeneous, reverse water–gas shift reaction (rWGSR) has been evaluated in quartz reactors with rapid feed preheating under both low‐ and high‐pressure conditions. The form of the power‐law rate expression was consistent with the Bradford mechanism. The Arrhenius expressions for the reaction rate constant, corresponding to the empty reactor, were in very good agreement with the low‐pressure results of Graven and Long, but yielded rate constants roughly four times greater than those obtained in our packed reactor and those reported by Kochubei and Moin and by Tingey. Reactor geometry was not responsible for these differences because computational fluid dynamics simulations revealed similar residence time distributions and comparable conversions when the same kinetic expression was used to model the rWGSR in each reactor. Most likely, the empty NETL reactor and the Graven and Long reactor did not attain an invariant value of the concentration of the chain carrier (H) at low reaction times, which led to an overestimation of the rate constant. Conversions attained in an Inconel® 600 reactor operating at comparable conditions were approximately two orders of magnitude greater than those realized in the quartz reactor. This dramatic increase in conversion suggests that the Inconel® 600 surfaces, which were depleted of nickel during the reaction, catalyzed the rWGSR. © 2004 American Institute of Chemical Engineers AIChE J, 50: 1028–1041, 2004
A kindred with Cockayne syndrome caused by multiple splicing variants of the CSA gene
Authors: Komatsu Ai , Suzuki Satoru , Inagaki Takeshi , Yamashita Koh , Hashizume Kiyoshi
Published: April 2004

Cockayne syndrome (CS) is an autosomal recessive disorder, which is associated with abnormal UV hypersensitivity, growth retardation, and psycho‐neural abnormalities. Recently, CSA protein was found to be associated with CS. We obtained mRNAs from immortal lymphoblasts derived from members of the kindred, and sequenced the CSA gene of all family members after reverse transcription (RT) of the coding region. The intact length of the CSA transcript was found in all family members except the proband with CS. Multiple abnormal splicing variant forms were revealed in all cases. No mutation was found in the sequences of the splice donor and acceptor sites of each exon in the CSA gene. UVA irradiation suppressed cell growth in the proband. There was no significant alteration of UVA sensitivity among the normal control and the family members except for the proband. These data suggest that multiple splicing variant forms of CSA mRNA, in the absence of the full‐length form of the mRNA, are associated with CS. © 2004 Wiley‐Liss, Inc.
SHOX mutations in a family and a fetus with Langer mesomelic dwarfism
Authors: Thomas N. Simon , Maloney Viv , Bass Paul , Mulik Varsha , Wellesley Diana , Castle Bruce
Published: April 2004

Léri–Weill dyschondrosteosis (LWD) and Langer mesomelic dysplasia (LMD) are caused by mutations in the SHOX gene. LWD results from haploinsufficiency and is dominantly inherited, while the more severe LMD results from the homozygous loss of SHOX. We describe a family and fetus with two SHOX mutations. Several relatives carry an approximately 200 kb interstitial deletion that includes the whole SHOX gene. Their condition is mild, with no Madelung deformity, and was originally diagnosed as hypochondroplasia (HCH). This deletion was also transmitted to a female fetus. However, unlike her carrier relatives, the ultrasound scan of the fetus and subsequent autopsy were consistent with LMD. The fetus inherited an additional Xp deletion (Xpter–Xp22.12) that also included the SHOX gene from her chromosomally normal father. This represents a unique molecular condition for LMD: the fetus is a compound heterozygote with two independent deletions, one inherited and one arising from a de novo event. © 2004 Wiley‐Liss, Inc.
Lack of adverse effects in pregnant/lactating female rats and their offspring following pre‐ and postnatal exposure to ELF magnetic fields
Authors: Chung Moon‐Koo , Kim Jong‐Choon , Myung Sung‐Ho
Published: April 2004

We have recently reported that exposure of pregnant rats to 60 Hz at field strengths up to 0.5 mT during the entire period of pregnancy did not induce any biologically significant effects on both pregnant dams and embryo‐fetal development. The present study was carried out to investigate the potential effects of gestational and lactational MF exposure on pregnancy, delivery, and lactation of dams and growth, behavior, and mating performance of their offspring in rats. Timed‐pregnant female Sprague–Dawley (SD) rats (24/group) received continuous exposure to 60 Hz magnetic field (MF) at field strengths of 0 (sham control), 5 μT, 83.3 μT, or 0.5 mT. Dams received MF or sham exposures for 21 h/day from gestational day 6 through lactational day 21. Experimentally generated MF was monitored continuously throughout the study. No exposure‐related changes in clinical signs, body weight, food consumption, pregnancy length, and necropsy findings were observed in dams. Parameters of growth, behavior, and reproductive performance of offspring showed no changes related to MF exposure. There were no adverse effects on embryo‐fetal development of F2 offspring from dams exposed to MF. In conclusion, exposure of pregnant SD rats to 60 Hz at field strengths up to 0.5 mT from gestational day 6 to lactational day 21 did not produce biologically significant effects in dams, F1 offspring, or F2 fetuses. Bioelectromagnetics 25:236–244, 2004. © 2004 Wiley‐Liss, Inc.
Use of a permanent magnetic field to inhibit the development of canine osteoarthritis
Authors: Rogachefsky Richard A. , Altman Roy D. , Markov Marko S. , Cheung Herman S.
Published: April 2004

This study was designed to determine the potential of a permanent magnetic field to inhibit the progression of osteoarthritis (OA) in a canine model. The magnetic field was created by 72 domino‐sized ceramic magnets with surface field strength of 1100 G (0.11 T). The magnetic field strength at the surface of the mattress was 450–500 G (45–50 mT) and was equally distributed over the mattress surface. Eighteen animals had closed resection of their right stifle anterior cruciate ligament. Their kennel floors were covered in one of three ways: no floor mattress (OA) (N = 6); a floor mattress with domino‐sized ceramic pieces placed between two layers of foam (sham control OA‐MAT) (N = 6); or a floor mattress with domino‐sized ceramic permanent magnets placed between two layers of foam (OA‐MAT‐MAG) (N = 6). Animals were kept in their cages except for 4 h of exercise each day. The left stifle of six animals served as the normal control. The stifle joints were examined at 12 weeks for synovial effusion, gross anatomic appearance, microscopic anatomic appearance (Mankin score), and metalloproteinase (MMP)‐1 and ‐3. Macroscopically, the OA‐MAT‐MAG group appeared to have less synovitis, less synovial effusion, less disruption of the cartilage surface, and less cartilage ulceration than did the OA group or the control mattress group. The mean Mankin score for the OA‐MAT‐MAG group was less than that for the OA group (4.2 ± 0.8 vs. 6.7 ± 0.3; P < .05) and the control mattress group (4.2 ± 0.8 vs. 5.2 ± 0.8; P > .05), but greater than that for the normal left group (4.2 ± 0.8 vs. 1.0 ± 0.4; P < .05). These scores show a trend of improvement for OA‐MAT‐MAG group but the difference with the sham control OA‐MAT group was not statistically significant. In immunohistochemical studies, the OA‐MAT‐MAG group cartilage was stained less heavily for MMP‐1 and MMP‐3 than were the OA group cartilage and the control mattress group cartilage, but did not differ significantly in MMP‐1 and MMP‐3 from the normal left group cartilage. The OA‐MAT‐MAG group did not differ from the normal left group in MMP‐3 as determined by Western blot analysis. The study suggests that OA of the medial femoral condyle developed in a canine model exposed to a magnetic field may be inhibited beyond the benefit provided by mattress. Further studies are needed to delineate more precisely the effect of the magnetic field in reducing the severity of OA. Bioelectromagnetics 25:260–270, 2004. © 2004 Wiley‐Liss, Inc.
The ribosome: lifting the veil from a fascinating organelle
Authors: Tate Warren P. , Poole Elizabeth S.
Published: April 2004

It was first suggested that the ribosome is associated with protein synthesis in the 1950s. Initially, its components were revealed as surface‐accessible proteins and as molecules of RNA apparently providing a scaffold for subunit shape. Attributing function to the proteins proved difficult, although bacterial protein L11 proved essential for binding one of the decoding protein release factors (RFs). With the discovery that RNA could be a catalyst, interest focussed on the rRNA that, in partnership with mRNA and tRNAs, could potentially mediate the chemical reaction underlying protein synthesis. rRNA interactions and conformational changes were invoked as key elements that facilitated function. The decoding RFs, which are proteins, are exceptions to this rule because they usurp a tRNA function in mediating stop signal recognition. Cryoelectron microscopy and associated image reconstruction technology have now given dramatic snapshots of almost every step of protein synthesis, and X‐ray crystallography has revealed, at last, the subunits and monomeric ribosome in exquisite atomic detail. BioEssays 26:582–588, 2004. © 2004 Wiley Periodicals, Inc.
Phylogeny of γ‐proteobacteria: resolution of one branch of the universal tree?
Authors: Brown James R. , Volker Craig
Published: April 2004

The reconstruction of bacterial evolutionary relationships has proven to be a daunting task because variable mutation rates and horizontal gene transfer (HGT) among species can cause grave incongruities between phylogenetic trees based on single genes. Recently, a highly robust phylogenetic tree was constructed for 13 γ‐proteobacteria using the combined alignments of 205 conserved orthologous proteins.1 Only two proteins had incongruent tree topologies, which were attributed to HGT between Pseudomonas species and Vibrio cholerae or enterics. While the evolutionary relationships among these species appears to be resolved, further analysis suggests that HGT events with other bacterial partners likely occurred; this alters the implicit assumption of γ‐proteobacteria monophyly. Thus, any thorough reconstruction of bacterial evolution must not only choose a suitable set of molecular markers but also strive to reduce potential bias in the selection of species. BioEssays 26:463–468, 2004. © 2004 Wiley Periodicals, Inc.
Metmyoglobin‐Catalyzed Exogenous and Endogenous Tyrosine Nitration by Nitrite and Hydrogen Peroxide
Authors: Nicolis Stefania , Monzani Enrico , Roncone Raffaella , Gianelli Luca , Casella Luigi
Published: April 2004

Metmyoglobin catalyzes the nitration of various phenolic compounds in the presence of nitrite and hydrogen peroxide. The reaction rate depends on the reactant concentrations and shows saturation behavior. Two competing paths are responsible for the reaction. In the first, myoglobin reacts according to a peroxidase‐like cycle forming two active intermediates, which can induce one‐electron oxidation of the substrates. The MbFeIVO intermediate oxidizes nitrite to nitrogen dioxide, which, after reaction with the phenol or with a phenoxy radical, yields the nitrophenol. In the second mechanism, hydrogen peroxide reacts with iron‐bound nitrite to produce an active nitrating species, which we assume to be a protein‐bound peroxynitrite species, MbFeIIIN(O)OO. The high nitrating power of the active species is shown by the fact that the catalytic rate constant is essentially independent of the redox properties of the phenol. The occurrence of one or other of these mechanisms depends on the nitrite concentration: at low [NO2−] the nitrating agent is nitrogen dioxide, whereas at high [NO2−] the peroxynitrite path is dominant. The myoglobin derivative that accumulates during turnover depends on the mechanism. When the path involving NO2. is dominant, the spectrum of the MbFeIVO intermediate is observed. At high nitrite concentration, the Soret band appears at 416 nm, which we attribute to an iron‐peroxynitrite species. The metMb/NO2−/H2O2 system competitively nitrates the heme and the endogenous tyrosine at position 146 of the protein. Phenolic substrates protect Tyr146 from nitration by scavenging the active nitrating species. The exposed Tyr103 residue is not nitrated under the same conditions.
Mechanism of Nitrosylmyoglobin Autoxidation: Temperature and Oxygen Pressure Effects on the Two Consecutive Reactions
Authors: Møller Jens K. S. , Skibsted Leif H.
Published: April 2004

As shown by singular value decomposition and global analysis of the absorption spectra, oxidation of nitrosylmyoglobin, MbFeIINO, by oxygen occurs in two consecutive (pseudo) first‐order reactions in aqueous air‐ saturated solutions at physiological conditions (pH 7.0, I=0.16 m (NaCl)). Both reaction steps have a large temperature dependence with the following activation parameters: ΔH${{{\ne}\hfill \atop 1\hfill}}$=121±7 and ΔS${{{\ne}\hfill \atop 1\hfill}}$=23±29; and ΔH${{{\ne}\hfill \atop 2\hfill}}$=88±14 kJ mol−1 and ΔS${{{\ne}\hfill \atop 2\hfill}}$=−63±51 J−1 K−1 mol−1 at 25 °C for the first and second step, respectively. At physiological temperature, the initial reaction is faster, while at lower temperatures, the first reaction is slower and rate‐determining. The rate of the first reaction is linearly dependent on oxygen pressure at lower pressures, while for oxygen pressures above atmospheric, the rate exhibits saturation behaviour. The second reaction is independent of oxygen pressure. The rate of the second reaction increases when oxymyoglobin is added. In contrast, the rate of the first reaction is independent of the presence of oxymyoglobin. The observed kinetics are in agreement with a reaction mechanism in which the nitric oxide that is initially bound to the FeII centre of myoglobin is displaced by oxygen in a reversible ligand‐exchange reaction prior to an irreversible electron transfer. The ligand‐exchange process is dissociative in nature and depends bond breaking, and nitric oxide is suggested to be trapped in a protein cavity. The absorption spectrum of the intermediate, as resolved from the global analysis, is in agreement with a peroxynitrite complex, and the initial process must involve partial electron transfer.
Computational Studies of Carbon Nanotube–Hydrocarbon Bond Strengths at Nanotube Ends: Effect of Link Heteroatom and Hydrocarbon Structure
Authors: Gustavsson Simon , Rosén Arne , Grennberg Helena , Bolton Kim
Published: April 2004

Semiempirical and density functional electronic structure theory methods were used to study SWNT‐XR bond strengths, where the single‐walled carbon nanotube (SWNT) had an armchair or zigzag structure, the link heteroatom X was O, N(H), or S and the hydrocarbon chain R was CH2CH3, CH(OH)CH3, CHCH2, or CH(CF3)CH3. In all systems the hydrocarbon was bonded to the end of the nanotube. The SWNT‐XR bond (that is, the bond joining the link atom to the hydrocarbon) is more than 0.4 eV stronger for armchair than for zigzag nanotubes with the same diameters, irrespective of whether O, N, or S are used as link atoms or whether OH, CC, or CF3 groups are present in the hydrocarbon chain. This raises the possibility for selective manipulation of armchair/zigzag nanotubes using a variety of link atoms and hydrocarbon structures. The SWNT‐OCH(CF3)CH3 bond is weaker than the SWNT‐OCH2CH3 bond (for both armchair and zigzag nanotubes), while inclusion of a double bond in the ethyl chain increases the bond strengths. Also, SWNT‐SCH2CH3 and SWNT‐N(H)CH2CH3 bonds are stronger than SWNT‐OCH2CH3 bonds.
Plutonium Chalcogenides and Pnictides: Pressure Induced Phase Transition and Elastic Properties.
Authors: Srivastava Vipul , Sanyal Sankar P.
Published: April 2004

For Abstract see ChemInform Abstract in Full Text.
Metaarsenate(V) Anion of Novel Constitution in AgAsO3.
Authors: Curda J. , Peters E.‐M. , Jansen M.
Published: April 2004

For Abstract see ChemInform Abstract in Full Text.
Optimization of Chromium Doping in LiNbO3 Single Crystals.
Authors: Kar S. , Bhatt R. , Bartwal K. S. , Wadhawan V. K.
Published: April 2004

For Abstract see ChemInform Abstract in Full Text.
Ti‐Triol Catalyzed Trimethylsilylcyanation of Acetophenones under High Pressure.
Authors: Choi Michael C. K. , Chan Shu‐Sun , Chan Man‐Kong , Kim Jong Chul , Iida Hirokazu , Matsumoto Kiyoshi
Published: April 2004

For Abstract see ChemInform Abstract in Full Text.
Stereoselective Zirconocene‐Mediated Ring Transformation of 2‐Vinylheterocycles to Vinylcarbocycles.
Authors: Hanzawa Yuji , Kiyono Hiromichi , Taguchi Takeo
Published: April 2004

For Abstract see ChemInform Abstract in Full Text.
Titanyl Acetylacetonate as an Efficient Catalyst for a Mild and Convenient Reduction of Carbonyl Compounds with NaBH4 under Aprotic Condition.
Authors: Zeynizadeh Behzad
Published: April 2004

For Abstract see ChemInform Abstract in Full Text.
A Convenient and Improved Montmorillonite K‐10 Catalyzed Friedel—Crafts Benzylation and Allylation with Activated Esters.
Authors: Karade N. N. , Shirodkar S. G. , Potrekar R. A.
Published: April 2004

For Abstract see ChemInform Abstract in Full Text.
Catalytic Generation of Indium Hydride in a Highly Diastereoselective Reductive Aldol Reaction.
Authors: Shibata Ikuya , Kato Hirofumi , Ishida Tatsuya , Yasuda Makoto , Baba Akio
Published: April 2004

For Abstract see ChemInform Abstract in Full Text.
Rapid Methylation of Terminal Acetylenes by the Stille Coupling of Methyl Iodide with Alkynyltributylstannanes: A General Protocol Potentially Useful for the Synthesis of Short‐Lived 11CH3‐Labeled PET Tracers with a 1‐Propynyl Group.
Authors: Hosoya Takamitsu , Wakao Masahiro , Kondo Yurie , Doi Hisashi , Suzuki Masaaki
Published: April 2004

For Abstract see ChemInform Abstract in Full Text.