bluuebunny/crossref_metadata_2025 huggingface dataset:
A Modulated Sample Introduction System for Atomic Emission Spectrometry
Authors: Steele A. W. , Hieftje G. M.
Published: July 2005

A modulated sample-introduction device for use in flame emission spectrometry has been constructed and evaluated. With this device, the flow of aerosol to the excitation source is modulated by the application, at a specific frequency, of a pressure pulse to the nebulizer chamber; the use of frequency-selective detection then permits efficient signal recovery. If source background remains at a constant level, it is not detected and the signal-to-background ratio (S/B) is consequently improved. Because the technique provides a decrease in the instrument 1/f and flame-background flicker noise, detection limits are improved. These features are especially prominent when the analyte line of interest is in a spectral region of high source background. Modulation frequencies of 8 to 20 Hz have been explored and have resulted in good depth of modulation (>99%) and signal-pulse separation. The construction and operation of the device will be described and its performance for several elements evaluated in terms of detection limits, S/B enhancement, and working curve linearity. Also, the extension of the technique to selective spectralline modulation schemes and to inductively coupled plasma emission spectrometry will be considered.
FT-IR Analysis of the Photolytic Laser-Induced Chemical Vapor Deposition of Germanium Films
Authors: Stanley A. E. , Johnson R. A. , Turner J. B. , Roberts A. H.
Published: July 2005

Germanium and doped-germanium polycrystalline films were formed with the use of photolytic CO2 laser-induced chemical vapor deposition. The compounds which yielded germanium in large quantities were germane, ethylgermane, and diethylgermane. Triethylgermane produces germanium in trace quantities. Gas-phase reactions were monitored with the use of Fourier transform infrared spectroscopy, also used for identification of end products. Scanning electron microscopy was used for analysis of the films. The products identified on irradiation of germane were germanium and hydrogen, with conversion rates of 86%. On irradiation of diethylgermane and ethylgermane, ethylene, germane, germanium, and hydrogen were produced. Germanium films doped with cadmium and aluminum were produced successfully by the irradiation of germane mixtures containing dimethylcadmium or trimethylaluminum, respectively.
Determination of Alcohols, Phenols, and Carboxylic Acids Using Phosphorus-31 NMR Spectroscopy
Authors: Schiff David E. , Verkade John G. , Metzler Robert M. , Squires Thomas G. , Venier Clifford G.
Published: July 2005

Derivatization of compounds containing -OH groups can be accomplished quantitatively with 1,3,2-dioxaphospholanyl chloride. The chemical shifts of phosphorus in the derivatives clearly differentiate alcohols from phenols and carboxylic acids. Quantitation is obtained by use of 31P FT-NMR spectroscopy in the presence of 2,2,6,6-tetrameth-ylpiperidinyloxy free radical to shorten relaxation times. Compounds with phosphorus chemical shifts differing by as little as 0.1 ppm can be separately determined.
Pulse Width Determination by Measuring the Normalized Second-Order Factorial Moment n(2)(T)
Authors: González F.
Published: July 2005

In this work a light beam composed of a series of periodically repeated pulses with a Lorentzian profile is studied by the use of a photon-counting multichannel analyzer and by the measurement of n(2)( Ti) ( i = 1, 2, …, K). The error in the determination of the width of the pulses is studied with the use of both methods and the results are compared.
An Application of Surface-Enhanced Raman Scattering to the Surface Characterization of Carbon Materials
Authors: Ishida H. , Fukuda H. , Katagiri G. , Ishitani A.
Published: July 2005

Surface-enhanced Raman scattering (SERS) has been successfully applied to the surface characterization of carbon materials such as highly oriented pyrolitic graphite, pyrolitic graphite, glassy carbon, diamond, and carbon fibers by the evaporation of Ag island films onto the surface. The surface chemical and morphological structure of carbon materials has been parallelly characterized by electron energy loss spectroscopy, x-ray photoelectron spectroscopy, and field-emission scanning electron microscope. Raman scattering from the outermost surface of carbon materials is found to be remarkably enhanced by the presence of Ag island films (50–100 Å). The chemical and crystal structure change of graphite and diamond by argon-ion etching has also been studied by the enhanced Raman spectra. The obtained results demonstrate the possibility of using SERS with the Ag overlayer method as a new high-sensitivity surface probe for various kinds of industrial materials.
Far-Infrared Spectroscopy in Diamond Anvil Cells
Authors: Challener W. A. , Thompson J. D.
Published: July 2005

A step-and-integrate Fourier transform spectrometer, a liquid-helium-cooled composite germanium bolometer, and specially configured non-focusing optics have been interfaced to gasketed diamond anvil cells. Simple molecular solids like iodine have been studied at pressures up to 16 GPa, frequencies down to 20 cm−1, and temperatures of 2 to 150 K with this arrangement. Evidence that spectroscopy in diamond anvil cells should be feasible to even lower frequencies and higher pressures is presented.
Slurry Method for Rapid DCP Atomic Emission Determination of Residual Bone Fragments in Mechanically Separated Turkey
Authors: Wichman M. D. , Fry R. C. , Hoffman M. K.
Published: July 2005

A slurry atomization direct current plasma (DCP) emission method is reported which involves a minimum of sample preparation for the spectroscopic determination of residual bone solids (as calcium) in mechanically separated turkey. Lengthy wet-ashing methods have been replaced here by a simple approach involving a 2-min “Polytron” homogenization step followed by shaking of the meat homogenate for ∼10 s with dilute nitric acid at room temperature. The sample bulk remains as a suspension of solids that is immediately and directly pumped to a clog-free Babington-type nebulizer installed in a three-electrode DCP emission spectrometer for Ca determination. Before homogenizing, mechanically separated turkey (MST) normally contains bone fragments in the particle size range 0.1 to 0.8 mm. For these MST samples, quantitative Ca recoveries are achieved by the new matrix-modified slurry atomization DCP atomic emission method within about 10 min of the time the meat product is received for bone solids analysis by the lab.
An Algorithm for the Reproducible Spectral Subtraction of Water from the FT-IR Spectra of Proteins in Dilute Solutions and Adsorbed Monolayers
Authors: Powell J. R. , Wasacz F. M. , Jakobsen R. J.
Published: July 2005

Spectral subtraction and baseline correction via interactive graphics programs have been extensively used for the analysis of weak IR absorption signals which are under strong bands, such as occur in aqueous protein solutions. However, personal bias and uncertainty can result in significant differences in the spectra of the same protein substracted and baseline corrected by different persons. This is demonstrated in the case of albumin adsorbed on the surface of a germanium ATR crystal in contact within pure water. A simple computer algorithm to automatically subtract the water spectrum and remove any baseline tilt or curvature, and thus remove this individual bias and uncertainty, is presented, with a comparison of the results between different persons and the algorithm.
Ultrapurification of Nitrogen Monitored by Metastable Transfer Emission Spectroscopy
Authors: Wittman P. K. , Mitchell J. W.
Published: July 2005

Metastable transfer emission spectroscopy (MTES) has been applied for on-line monitoring of nitrogen purity. The relative efficiencies of various purification techniques for removing oxygen- and carbon-containing impurities have been compared. Total oxygen impurities present initially at several hundred ppm are reduced to <50 ppb with a reactive resin. Several other conventional laboratory purification methods reduce, but do not eliminate, oxygen contamination. Hydrocarbon impurities as methane are reduced only to the 3 ppm level by a liquid-nitrogen cold trap. Further reduction is obtained by the use of the microwave discharge as a chemical reactor prior to liquid-nitrogen trapping. An on-line system for the direct purification and reliable monitoring of nitrogen purity in a flowing gas stream is reported.
Simplified Slurry Method for Direct Flame Emission Determinations of Dietary Salt in Processed Meat
Authors: Wichman M. D. , Fietkau R. , Fry R. C.
Published: July 2005

The rapid, direct slurry atomization flame emission procedure for Na and K determination is shown to give accurate results for a variety of processed meats including bologna, salami, sausage, ham, bacon, and pizza products. Wet and dry ashing methods are found to be unnecessary in this application. The sample preparation scheme for the elements Na and K has been even further simplified over our previous slurry atomization report (Ref. 1) by elimination of the sonic/cavitational homogenizer in favor of an ordinary household food processor (meat grinder). Ground meat or pizza is simply suspended by being shaken in some deionized water followed immediately by direct flame emission analysis of the suspension using a slurry nebulizer and a high-solids premixed natural-gas/air flame. A simple clinical-type filter photometer is evaluated as a substitute for the grating instrument previously used for the determination of dietary salt in processed meat by slurry atomization.
System Optimization for the Automatic Simultaneous Determination of Arsenic, Selenium, and Antimony, Using Hydride Generation Introduction to an Inductively Coupled Plasma
Authors: Pyen Grace S. , Long Stephen , Browner Richard F.
Published: July 2005

A fixed-size simplex has been used to determine the optimum conditions for the simultaneous determination of arsenic, selenium, and antimony by hydride generation and inductively coupled plasma emission spectrometry. The variables selected for the simplex were carrier gas flow rate, rf power, viewing height, and reagent conditions. The detection limit for selenium was comparable to the preoptimized case, but there were twofold and fourfold improvements in the detection limits for arsenic and antimony, respectively. Precision of the technique was assessed with the use of artificially prepared water samples.
Optimal Wavelength Selection for Quantitative Analysis
Authors: Sasaki K. , Kawata S. , Minami S.
Published: July 2005

A new computer algorithm has been developed for selecting the optimal set of wavelengths for spectroscopic quantitative analysis of mixture samples. The method is based on the criterion of the minimum mean square error between concentrations of the mixture components and their estimates. The branch and bound algorithm finds the optimal set from all possible combinations of wavelengths. This algorithm saves computation time significantly, compared with the enumerative method. The mathematical formulation of the lower bound of the mean square errors for the combinations in a given subset is derived as a recurrence inequality. Experimental results of wavelength selection for infrared absorption spectra of xylene-isomer mixtures are shown to demonstrate the effectiveness of the algorithm in terms of computation complexity and accuracy in quantitative analysis for the fixed measurement time.
Dynamic FT-IR. Part I: Rapid-Scan Methods in Spectroelectrochemistry
Authors: Yaniger Stuart I. , Vidrine D. Warren
Published: July 2005

Current rapid-scan FT-IR instrumentation allows medium resolution (16 cm−1) infrared spectra to be acquired and separately stored at a rate of 85 spectra per second with excellent signal-to-noise ratio. This corresponds to a time resolution of about 12 ms. Higher spectral resolutions are possible at a cost of some spectrometer speed. Rapid-scan FT-IR provides a means by which the course of electrochemical reactions can be followed and, unlike digital time-resolved and double-modulation FT-IR, this method is not limited to reversible reactions and may be used with impunity by the nonspecialist. We examine several examples of irreversible electrochemical processes including solution-phase redox chemistry, electropolymerizations, and doping reactions of conducting polymers.
A Spectrometric Technique for Monitoring [O2(a1 Δg)] in the Gas Phase
Authors: Coxon J. A. , Roychowdhury U. K.
Published: July 2005

The reaction of chlorine with alkaline hydrogen peroxide has been used to produce O2( a1 Δ g) in a fast flow system at partial pressures up to about 0.5 Torr, and total pressures (mostly argon) in the range 0.8–2.5 Torr. Absolute concentrations of O2( a1 Δ g) were determined from the intensity of absorption of hydrogen emission lines in the vacuum-UV at 144.095 and 148.66 nm, for which the cross sections are known. The intensity of the O2 ( a → X) transition at 1270 nm, monitored simultaneously with a simple germanium detector, was found to vary linearly with [O2( a1 Δ g)], as expected. The germanium detector was calibrated at 1270 nm with a readily reproducible standard, the air afterglow continuum due to NO2* at defined concentrations of O(3P) and NO. The ratio of ka for O2( a) ka O 2( X) + hvt to kc for O + NO kc NO2 + hv, is (1.4 ± 0.2) × 10−7 mol L−1 at 1270 nm.
Sensitive Photothermal Deflection Detector for Microbore Liquid Chromatography
Authors: Collette T. W. , Parekh N. J. , Griffin J. H. , Carreira L. A. , Rogers L. B.
Published: July 2005

A photothermal deflection detector for microbore liquid chromatography is described. The detection limit of the system under isocratic flow conditions is shown to be 8 × 10−8 absorbance units. This corresponds to 500 fg of analyte (acid sulfonate rug dye) injected on the column. The detection system is shown to be amenable to gradient elution and open tubular chromatography.
Concentration Profiling in Layered Liquids Using a Laser Photoacoustic Probe
Authors: Wylie Ian W. , Lai Edward P. C.
Published: July 2005

An aluminum-coated Pyrex® glass rod is used both as a photoacoustic probe and as a laser light guide to examine a three-layer solution of carbon tetrachloride, hexane, and an aqueous solution of an efficient chromophore, ferroin. The boundaries of the layers show up clearly on a signal amplitude vs. penetration depth graph. A Beer's law plot of the ferroin solution alone shows that the probe is capable of analytical determinations down to 10−7 M. Reflections from the cell walls may cause interference in quantitative analysis if the size of the cell is too small. The sensitivity of the probe is compared with that of a typical photoacoustic cell, and it is found that the probe only attenuates the signal amplitude by ∼35%. Finally, it is found that the signal amplitude transmitted by the photoacoustic probe is roughly proportional to its diameter.
A Variable-Temperature Hydrostatic Pressure Cell for Raman Scattering Experiments
Authors: Martin J. J. , Cavagnat R. , Cornut J. C. , Couzi M. , Daleau G. , Devaure J. , Maissara M. , Mokhlisse R.
Published: July 2005

A variable-temperature hydrostatic high-pressure cell for Raman scattering experiments is presented; it can be commonly used for pressures up to about 6 kbars, in the temperature range between 340 and 80 K. Examples of applications are given, concerning conformational equilibriums in liquid tridecane on the one hand, and structural phase transitions in crystalline (CH3)4NMnCl3(TMMC) and (CH3)4NCdCl3 (TMCC), on the other hand.
A Comparison of Excitation Conditions between Conventional and Low-Flow, Low-Power Inductively Coupled Plasma Torches
Authors: Burton L. L. , Blades M. W.
Published: July 2005

FeI excitation temperatures have been measured for both conventional and low-flow, low-power ICP torches. Temperatures were measured from 0 to ± 6 mm radial position at 4, 8, 12, 16, and 20 mm above the load coil. In addition, radial and vertical spatial emission profiles for FeI and FeII have been measured for both torches. The results indicate that the gas flow dynamics are different for the two torches and this in turn creates a different excitation environment for each torch.
Depth Profile Study of Large-Sized Coal Samples by Fourier Transform Infrared Photoacoustic Spectroscopy
Authors: Zerlia Tiziana
Published: July 2005

A multidisciplinary approach is demonstrated to elucidate coal weathering at a molecular level. Fourier Transform Infrared Photoacoustic Spectroscopy (FT-IR/PAS) provides a technique for a compositional depth profile of coal by simply varying the modulation frequency (mirror velocity) of the light impinging upon the solid surface. In order that the potential of this technique in this field could be evaluated, large-sized coal samples were examined. The PA difference spectra obtained from the spectra taken at different modulation frequencies (i.e., different depths), on a sample aged in air, demonstrate the appearance of negative features in the CH infrared absorption which are indicative of a coal alteration. Therefore, different coal layers can be distinguished by FT-IR/PAS. The application of the same technique to the study of a coal sample heated in air at 200°C allows the detection of different oxidation mechanisms operating inside and outside the coal. Although quantitative results are difficult to obtain, the technique can be successfully proposed for a qualitative description of coal weathering.
The UV Absorption Spectra of Chemical Agents and Simulants
Authors: Rewick Robert T. , Schumacher Mary L. , Haynes Daniel L.
Published: July 2005

The uv spectra of chemical agents GA, GB, GD, VX, HD, and L and common agent simulants have been measured in cyclohexane solution from 350 to 200 nm. The purity of the agents, measured by gas chromatographic analysis, was in general >96%. At 230 nm, the strength of the uv absorption followed the general trend L > VX > GA > HD > GD > GB > DMMP. Except for HD and L, agent spectra lacked characteristic features that will be useful for remote detection by uv sensors.
Applications of Transmittance and Reflectance Micro/FT-IR to Polymeric Materials
Authors: Harthcock M. A. , Lentz L. A. , Davis B. L. , Krishnan K.
Published: July 2005

Recent advances in FT-IR microsampling techniques have increased the specificity with which infrared spectra of microscopic samples or regions of microscopic samples can be obtained. In this paper, application of microsampling techniques to several problems involving polymeric materials will be presented. The technique using transmittance methods is shown to be a fast method for isolating two particles in a heterogeneous mixture and obtaining infrared spectra to conclusively identify the particles. The infrared absorption spectra of several layers of a multilayer polymer structure ranging in size from 8 to 50 μm are identified with the use of the technique. The surface of an imperfection in a painted polymer (approximately 150 μm diameter) is studied with the use of the infrared reflectance capabilities. These microsampling techniques prove useful and unique for specialized problems involving polymeric materials. The data obtained by the use of these microsampling techniques could not be obtained by “conventional” microsampling methods.
Infrared Group Frequency Correlations for Styrenes, α-Methylstyrenes, and Related Compounds
Authors: Nyquist R. A.
Published: July 2005

Infrared group frequency correlations are presented which aid in spectra-structure identification of styrenes, α-methylstyrenes, and related compounds. The vinyl and phenyl groups in styrene are coplanar in only those cases where atoms or groups such as Cl and CH3 are not substituted in the 2,6-positions, and the isopropenyl and phenyl groups in α-methylstyrenes are coplanar in only those cases where atoms or groups such as Cl and CH3 are not substituted in one ortho-position. Steric factors prevent the vinyl and phenyl groups from being coplanar in styrene substituted with atoms or groups in at least the 2,6-positions, and steric factors also prevent the isopropenyl and phenyl groups from being coplanar in 2-substituted α-methylstyrenes.
Fundamental Studies in the ICP Using a Sinusoidally Modulated Power Input
Authors: Parisi A. F. , Hieftje G. M.
Published: July 2005

The power input into an inductively coupled plasma has been modulated over the frequency range of 200 to 400 Hz. It was found that the plasma exhibits a nonlinear response to changes in power. In addition, the maximum excitation temperature is correlated to the peak of the modulation waveform, whereas the fluorescence intensity and therefore species number density is related to the valley of the modulation. The measured delays are a function of observation height and studied analyte but are frequency independent. Gas dynamics, energy transfer, or sample decomposition rates are suggested to be responsible for the delays.
π* ← π Shakeup Satellites for the Analysis of Structure and Bonding in Aromatic Polymers by X-Ray Photoelectron Spectroscopy
Authors: Gardella Joseph A. , Ferguson Susan A. , Chin Roland L.
Published: July 2005

The applications of ESCA to polymer surface analysis include the use of the secondary final-state effects which lead to satellite structure near the core-level photoemission (PE) lines. Specifically, unsaturated and aromatic functionalities in organic compounds and polymers lead to π* ← π shakeup peaks of less than 10 eV lower kinetic energy (higher binding energy). In the surface analysis of polymers, these features can be utilized for qualitative analysis, identification of the presence and structure of aromatic bonding, and quantitative analysis in determining the amount of a particular block or the aromatic containing function in the near-surface region. Carbon Is shakeups are most often used, but the present study includes detailed qualitative and quantitative analysis of shakeup structures from PE lines from each type of atom in hydrocarbon-, siloxane-, and sulfur-containing polymers. These results show the importance of including the shakeup intensity in quantitative peak area calculations and in peak fitting of complex PE envelopes. These studies prove in a variety of systems that the effects of third-row atoms on the final state lead to the presence of shakeup features in atoms with orbitals which do not participate in the aromatic orbital initial state, thus complicating interpretation of structure from the presence of these features. Results from the siloxane and sulfone polymers indicate that previously held assumptions about the nature of the initial-state molecular orbital may overlook the contribution of empty 3d orbitals or increased charge density on the Si or S atom which would spread the pi orbitals to the oxygen in the aromatic siloxane or sulfone systems. Finally, analysis of these features can provide quantitative analysis of polymeric surface structure by monitoring the relative intensity of the feature to the main PE line.
Selective Observation of Chlorophyll c in Whole Cells of Diatoms by Resonant Raman Spectroscopy
Authors: Wagner W.-D. , Waidelich W.
Published: July 2005

A surface scanning technique was used to obtain resonant Raman spectra from chlorophylls in solution and in whole cells of diatoms at 80 K. When in vivo samples are excited at 457.9 nm, chlorophyll c becomes observable in the recorded Raman spectra, as shown by comparison with in vitro measurements. In the field of photosynthetic research this becomes Interesting, as chlorophyll c can hardly be detected in electronic absorption spectra from whole cells, even at low temperatures, because of its weak Q bands compared with other plant chlorophylls. Chl a spectra were obtained with the use of 441.6-nm excitation. Working with two-channel recording, we eliminated the solvent contribution from the Raman spectra of pigments in vitro. Moreover, the technique facilitates detection of Raman excitation profiles from pigment lines in vivo at low temperatures by use of a nonresonating reference in the second sample chamber.
Fourier Self-Deconvolved Infrared Spectra as an Aid to Conformational Studies on Poly(Vinyl Chloride)
Authors: Compton David A. C. , Maddams William F.
Published: July 2005

Fourier self-deconvolution has been used to enhance the detail present in the carbon-chlorine stretching region of the infrared spectra of three samples of polyvinyl chloride) covering a range of syndiotacticities. The results are of interest both as a good example of the scope and limitations of Fourier self-deconvolution and because they complement the information on the conformational structure of these polymers obtained previously by other peak-finding methods. In the former context, the results show that the use of varying degrees of over-deconvolution is advantageous in dealing with systems of overlapping bands having a range of half widths. With respect to the conformational structure of poly(vinyl chloride), the most significant conclusion is that the frequency of the B1 mode of long syndiotactic sequences is dependent on both polymer tacticity and the form in which the sample is examined. The implications of this finding for the use of curve fitting are discussed briefly.
Limitations to Quantitative Analysis of Fluid Inclusions in Geological Samples by Laser Raman Microprobe Spectroscopy
Authors: Wopenka Brigitte , Pasteris Jill Dill
Published: July 2005

The theoretical parameters underlying quantitative Raman spectroscopy [relative normalized differential Raman scattering (RNDRS) cross sections] are discussed. A method is described [based on Placzek's polarizability theory (see text for reference)] by which relative abundances of species of geological interest (e.g., CO2, CH4, SO2) in individual fluid inclusions are analyzed in practice. Whereas the precision of the analysis is determined by “practical limitations” (which include counting statistics and instrumental reproducibility), its accuracy depends on “practical” as well as “theoretical limitations.” The latter are due to uncertainties in the available RNDRS cross sections. These uncertainties are so large (or even unknown to date, e.g., for liquid or high-pressure gas phases) that it becomes very difficult to estimate the accuracy of the final result. By making the (not very realistic) assumption that the RNDRS cross sections available in the literature apply to the individual fluid inclusion under analysis as well as to the instrumental configuration, we determined the mean composition of a set of synthetic fluid inclusions to be 14.8 ± 2.0 mole % CH4 and 85.2 ± 2.0 mole % CO2.
Analysis of Lateritic Material from Cerro Impacto by Instrumental Neutron Activation Employing a Low-Energy Photon Semiconductor and a High-Energy Ge(Li) Detector
Authors: Labrecque J. J. , Beusen J. M. , Van Grieken R. E.
Published: July 2005

Nineteen elements were determined in four different grain size fractions of a bulk geological material from Cerro Impacto for a study of the physical (mechanical) concentration process of different elements based upon the hardness of the different minerals. The analysis was performed by excitation of the sample with a high, slow neutron flux followed by gamma-ray spectroscopy with both a conventional Ge(Li) high-energy detector and a low-energy photon detector (LEPD). The accuracy of this method was studied with the use of two standard reference materials, SY-2 and SY-3, which are similar to the real samples. The values determined were also compared with a secondary target x-ray fluorescence method for all the elements that were suitable to both methods. Actually, the x-ray fluorescence method was found to be more complementary than competitive.
Angular Dependence of Diffuse Reflectance Infrared Spectra. Part I: FT-IR Spectrogoniophotometer
Authors: Brimmer Paul J. , Griffiths Peter R. , Harrick N. J.
Published: July 2005

An optical arrangement is described which allows diffuse reflectance infrared spectra to be collected by the use of a variety of incident angles and collection geometries. In the first phase of this study, the reflectance from a nonabsorbing powder and the intensity of the reststrahlen band in quartz were monitored as a function of optical geometry. The contribution of Fresnel reflectance was found to be very dependent on optical geometry, and the effect on the intensity of absorption bands in diffuse reflectance spectra is demonstrated. Based on these preliminary results, some suggestions for minimizing Fresnel reflectance through the optimization of diffuse reflectance optics are made.
In Situ Resonance Raman Spectroscopic Characterization of Electrogenerated Methyl Viologen Radical Cation on Carbon Electrode
Authors: Datta Monika , Jansson Robert E. , Freeman John J.
Published: July 2005

In situ Raman spectroscopic characterization of solution and surface species on a carbon electrode is reported. An optical flow-through cell has been designed for the characterization of electrode surfaces and electrogenerated solution species during an electrochemical reaction. The electrogeneration of the methyl viologen (1,1′-dimethyl-4,4′-bipyridine) radical cation (MV+) at a carbon electrode in aqueous chloride solution has been studied with the use of laser Raman spectroscopy. In the case of the radical ion, resonance enhancement of the order of 25–30 was observed with 514.5 nm excitation. The effect of concentration, potential, and flow rate on the observed spectrum is discussed. Time-dependent studies with optical multichannel analyzer detection suggest the formation of a multilayer film on the electrode.
Prey Community Responses to Bluegill and Gizzard Shad Foraging: Implications for Growth of Juvenile Largemouth Bass
Authors: Aday D. Derek , Shoup Daniel E. , Neviackas Justin A. , Kline Jeffrey L. , Wahl David H.
Published: July 2005

Bluegill Lepomis macrochirus, gizzard shad Dorosoma cepedianum, and largemouth bass Micropterus salmoides are common lentic species that may compete for invertebrate prey resources, and interactions among these species can have important consequences for aquatic community structure. Differential foraging behavior of bluegills and gizzard shad as juveniles, for example, may structure zooplankton and benthos communities and influence the growth of juvenile largemouth bass. We conducted a mesocosm experiment (1.6‐m‐diameter circular tanks) in which we allowed high and low densities of juvenile bluegills (70–100 mm total length [TL]) and gizzard shad (135–155 mm TL) to forage on established zooplankton and benthos communities for 6 weeks. After this period, we added juvenile largemouth bass (50–80 mm TL) to each tank for 4 weeks to examine growth and diets. Although foraging by bluegill and gizzard shad had limited effects on the total population densities of invertebrates, important taxon‐specific effects were observed. At the time that largemouth bass were added to tanks, bluegill treatments exhibited a higher macrozooplankton density, higher turbidity, and lower density of larval hydrophilid coleopterans than did gizzard shad or control treatments. The growth of juvenile largemouth bass was strongly influenced by treatment; largemouth bass grew at similar rates in the gizzard shad and control treatments but lost weight in the bluegill treatments. We suggest that bluegills compete with juvenile largemouth bass for preferred prey items, thereby limiting largemouth bass growth. Further, our results demonstrate that the presence of larger gizzard shad may not have the negative implications observed in previous studies with smaller individuals. Knowledge of the relative, size‐specific abundances of bluegills and gizzard shad should provide resource managers with valuable information for developing initiatives aimed at maximizing the growth of juvenile largemouth bass.
Achieving Individual‐Nanotube Dispersion at High Loading in Single‐Walled Carbon Nanotube Composites (Adv. Mater. 2005, 8, 980)
Authors: Graff R. A. , Swanson J. P. , Barone P. W. , Baik S. , Heller D. A. , Strano M. S.
Published: July 2005

To view the original paper use http://dx.doi.org/10.1002/adma.200401218>.
Inside Front Cover: Line Defects Embedded in Three‐Dimensional Photonic Crystals (Adv. Mater. 15/2005)
Authors: Yan Q. , Zhou Z. , Zhao X. S. , Chua S. J.
Published: July 2005

The inside cover illustrates an approach to creating line defects embedded in the interior of a self‐assembled photonic crystal, as reported by Zhao and co‐workers on p. 1917. Photoresist patterns are first constructed on the surface of a silica opal film by conventional optical photolithography. After regrowth of the silica colloidal crystal, photoresist line defects are successfully introduced into the self‐assembled silica colloidal crystal. Further processing results in an inverse opal with air‐core line defects embedded in its interior, which provides a prototype for future optical waveguide devices based on self‐assembled three‐dimensional photonic crystals.
Shipwrecks and founder effects: Divergent demographic histories reflected in Caribbean mtDNA
Authors: Salas Antonio , Richards Martin , Lareu María‐Victoria , Sobrino Beatriz , Silva Sandra , Matamoros Mireya , Macaulay Vincent , Carracedo Ángel
Published: July 2005

During the period of the Atlantic slave trade (15th–19th centuries), millions of people were forced to move from Africa to many American destinations, changing dramatically the human landscape of the Americas. Here, we analyze mitochondrial DNA from two different American populations with African ancestry, with hitherto unknown European and Native American components. On the basis of historical records, African‐Americans from Chocó (Colombia) and the Garífunas (or “Black Carib”) of Honduras are likely to have had very different demographic histories, with a significant founder effect in the formation of the latter. Both the common features and differences are reflected in their mtDNA composition. Both show a minor component (∼16%) from Native Central/South Americans and a larger component (∼84%) from sub‐Saharan Africans. The latter component is very diverse in the African‐Americans from Chocó, similar to that of sub‐Saharan Africans, but much less so in the Garífunas, with several mtDNA types elevated to high frequency, suggesting the action of genetic drift. Am J Phys Anthropol, 2005. © 2005 Wiley‐Liss, Inc.
Clinical course in young patients with sporadic Creutzfeldt–Jakob disease
Authors: Boesenberg Constanze , Schulz‐Schaeffer Walter J. , Meissner Bettina , Kallenberg Kai , Bartl Mario , Heinemann Uta , Krasnianski Anna , Stoeck Katharina , Varges Daniela , Windl Otto , Kretzschmar Hans A. , Zerr Inga
Published: July 2005

Sporadic Creutzfeldt–Jakob disease (sCJD) is a rare neurodegenerative disease with the greatest incidence occurring in patients between 60 and 70 years old. Younger patients may also be affected. In this study, we used all case material available from 52 patients with sCJD aged 50 years or younger at disease onset, who were identified between 1993 and 2003 in Germany. The objective of this study was to describe the psychiatric and neurological features of these young patients with emphasis on the different codon 129 genotypes and PrP types, and to compare them with elder patients with sCJD and patients with variant CJD. We also gave particular attention to electroencephalogram, magnetic resonance imaging, and 14‐3‐3 results, as well as to the neuropathological lesion profile. The clinical syndrome in young patients differs from elder patients with CJD with respect to clinical signs, disease duration, technical investigations, and neuropathological lesion profile. The psychiatric symptoms in young patients with sCJD are similar to the psychiatric symptoms expressed by patients with variant CJD; however, in contrast with the variant cases, young patients with sCJD experience development of prominent dementia early in the disease course. Ann Neurol 2005
Preparation and adsorption behavior of macrocyclic tetra‐amine derivatives of chitosan
Authors: Yang Zhikuan , Liu Liangdong , Zhang Lin , Wang Yuting
Published: July 2005

The new macrocyclic polyamine derivatives of chitosan were synthesized by reacting epoxy‐activated macrocyclic tetra‐amine with the C6 hydroxyl or C2 amino group in chitosan. The obtained copolymers (CTS‐OM, CTS‐NM) contain amino functional groups, the secondary amines, and more polar hydroxyl groups in its skeleton. Elemental analysis, infrared spectra, and solid‐state 13C‐NMR analysis confirmed their structures. The adsorption behavior of the macrocyclic polyamine grafted chitosan for Ag+, Pb2+, Hg2+, and Cr3+ was investigated. The experimental results showed that the two novel derivatives of chitosan have high adsorption capacity and good selectivity for some metal ions. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 407–412, 2005
Coating of jute with natural rubber
Authors: Das D. , Datta M. , Chavan R. B. , Datta S. K.
Published: July 2005

Jute fabric was coated with natural rubber to develop double‐texture rubberized waterproof fabric and fabric‐reinforced rubber sheeting for hospitals. The vulcanization of such natural‐rubber‐coated flexible composites at 120°C for 3 h produced optimum effects. The jute/natural‐rubber composite was much superior to a conventional polyester/natural‐rubber composite for producing such double‐texture rubberized fabric with respect to the fabric‐to‐natural‐rubber adhesion, breaking strength, tear strength, abrasion resistance, puncture resistance, and biodegradability. For fabric‐reinforced rubberized sheeting, the jute/natural‐rubber composite was superior to a conventionally used cotton/natural‐rubber composite with respect to the fabric‐to‐natural‐rubber adhesion, breaking strength, tear strength, and abrasion resistance. However, for both applications, the jute‐based products were commonly found to be less extensible, heavier, and thicker. Unsaturation in the lignin fraction of jute established a chemical linkage with the unsaturation of natural rubber via sulfur at the jute/natural‐rubber interface. An examination of the surface morphology of uncoated and coated jute fabrics by scanning electron microscopy revealed a good degree of deposition and filling even in the intercellular regions of jute by a cohesive mass of natural rubber, which remained unseparated from the fiber, when mechanical force was applied. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 484–489, 2005
Effect of chromium aging on the structural and thermal properties of chromium polyacrylate
Authors: Öztürk Ö. F. , Köse D. A. , Ay A. N. , Zümreoglu‐Karan B.
Published: July 2005

The effects of aging time of Cr(III) solutions on the structural, thermal, magnetic, and morphological properties of chromium polyacrylate complexes were studied. Chromium retention was found to increase with longer aging periods. IR spectra revealed the formation of polychelate structures with noticeable changes on aging. The interaction of multivalent, polynuclear Cr(III) species with the polymer backbone resulted in a decrease in thermal stability for the complexes prepared from olated chromium solutions. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 490–493, 2005
Osteoblasts engulf apoptotic bodies during alveolar bone formation in the rat maxilla
Authors: Cerri Paulo Sérgio
Published: July 2005

During bone formation, as in other tissues and organs, intense cellular proliferation and differentiation are usually observed. It has been described that programmed cell death, i.e., apoptosis, takes place in the control of the cellular population by removing of the excessive and damaged cells. Although it is generally accepted that apoptotic bodies are engulfed by professional phagocytes, the neighboring cells can also take part in the removal of apoptotic bodies. In the present study, regions of initial alveolar bone formation of rat molars were examined with the aim to verify whether osteoblasts are capable of engulfing apoptotic bodies, such as professional phagocytes. Rats aged 11–19 days were sacrificed and the maxillary fragments containing the first molar were removed and immersed in the fixative solution. The specimens fixed in glutaraldehyde‐formaldehyde were processed for light microscopy and transmission electron microscopy. For the detection of apoptosis, the specimens were fixed in formaldehyde, embedded in paraffin, and submitted to the TUNEL method. The results revealed round/ovoid structures containing dense bodies on the bone surface in close contact to osteoblasts and in conspicuous osteoblast vacuoles. These round/ovoid structures showed also positivity to the TUNEL method, indicating that bone cells on the bone surface are undergoing apoptosis. Ultrathin sections showed images of apoptotic bodies being engulfed by osteoblasts. Occasionally, the osteoblasts exhibited large vacuoles containing blocks of condensed chromatin and remnants of organelles. Thus, these images suggest that osteoblasts are able to engulf and degrade apoptotic bodies. © 2005 Wiley‐Liss, Inc.
LEK1 protein expression in normal and dysregulated cardiomyocyte mitosis
Authors: Dees Ellen , Robertson J. Brian , Ashe Mabelle , Pabón‐Peña Lil M. , Bader David , Goodwin Richard L.
Published: July 2005

A defining characteristic of embryonic cells is their ability to divide rapidly, even in tissues such as cardiac muscle, which cannot divide once fully differentiated. This suggests that regulators of cell division differ in embryonic and differentiated cells. LEK1 is a member of an emerging family of proteins with diverse functions but shared structural domains, including numerous leucine zippers, a nuclear localization site, and a functional Rb‐binding domain. LEK1 is expressed ubiquitously in the developing mouse embryo from the earliest stages of differentiation through birth. It is absent in adult tissues, even those that maintain active cell division. We hypothesize that LEK1 is a regulator of mitosis restricted to the developing embryo and early neonate. Here, using BrdU incorporation, we show that LEK1 protein downregulation in cardiac myocytes correlates directly with cessation of DNA synthesis between neonatal days 6 and 10. In contrast, in an immortalized cardiac cell line (HL1 cells), both BrdU incorporation and LEK1 protein expression persist, and actively dividing cells express LEK1. However, BrdU incorporation can be decreased in these cells by treatment with a morpholino targeting LEK1 mRNA. These data suggest a role for LEK1 in regulating the normal embryonic cardiomyocyte cell cycle and in promoting continued mitosis in transformed, abnormally dividing cardiomyocytes. © 2005 Wiley‐Liss, Inc.
The heat of the moment: the effect of sexual arousal on sexual decision making
Authors: Ariely Dan , Loewenstein George
Published: July 2005

Despite the social importance of decisions taken in the “heat of the moment,” very little research has examined the effect of sexual arousal on judgment and decision making. Here we examine the effect of sexual arousal, induced by self‐stimulation, on judgments and hypothetical decisions made by male college students. Students were assigned to be in either a state of sexual arousal or a neutral state and were asked to: (1) indicate how appealing they find a wide range of sexual stimuli and activities, (2) report their willingness to engage in morally questionable behavior in order to obtain sexual gratification, and (3) describe their willingness to engage in unsafe sex when sexually aroused. The results show that sexual arousal had a strong impact on all three areas of judgment and decision making, demonstrating the importance of situational forces on preferences, as well as subjects' inability to predict these influences on their own behavior. Copyright © 2005 John Wiley & Sons, Ltd.
M.TaqI facilitates the base flipping via an unusual DNA backbone conformation
Authors: Wibowo Fajar R. , Rauch Christine , Trieb Michael , Liedl Klaus R.
Published: July 2005

MD simulations have been carried out to understand the dynamical behavior of the DNA substrate of the Thermus aquaticus DNA methyltransferase (M.TaqI) in the methylation process at N6 of adenine. As starting structures, an x‐ray structure of M.TaqI in complex with DNA and cofactor analogue (PDB code: 1G38) and free decamer d(GTTCGATGTC)2 were taken. The x‐ray structure shows two consecutive BII substates that are not observed in the free decamer. These consecutive BII substates are also observed during our simulation. Additionally, their facing backbones adopt the same conformations. These double facing BII substates are stable during the last 9 ns of the trajectories and result in a stretched DNA structure. On the other hand, protein–DNA contacts on 5′ and 3′ phosphodiester groups of the partner thymine of flipped adenine have changed. The sugar and phosphate parts of thymine have moved further into the empty space left by the flipping base without the influence of protein. Furthermore, readily high populated BII substates at the GpA step of palindromic tetrad TCGA rather than CpG step are observed in the free decamer. On the contrary, the BI substate at the GpA step is observed on the flipped adenine strand. A restrained MD simulation, reproducing the BI/BII pattern in the complex, demonstrated the influence of the unusual backbone conformation on the dynamical behavior of the target base. This finding along with the increased nearby interstrand phosphate distance is supportive to the N6‐methylation mechanism. © 2005 Wiley Periodicals, Inc. Biopolymers 79: 128–138, 2005

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Insekten auf Leichen: Forensische Entomologie
Authors: Amendt Jens , Zehner Richard , Krettek Roman
Published: July 2005

Ein menschlicher Leichnam dient einer Vielzahl von Insekten und anderen Gliedertieren als Lebensraum und Nahrungsquelle. Die Forensische Entomologie nutzt diese Tatsache und analysiert Insektenspuren an einer Leiche und ihrer unmittelbaren Umgebung, um kriminalistische und rechtsmedizinische Fragen zu beantworten. Dabei steht vor allem die Klärung des Todeszeitpunktes im Mittelpunkt, der mit klassischen rechtsmedizinischen Methoden bereits nach 24 bis 48 Stunden nicht mehr einzugrenzen ist. Kenntnisse zur Biologie und Ökologie nekrophager Insekten können hier maßgeblich zur Aufklärung eines Todesfalles beitragen.
Flügel täuscht Geschwister vor
Authors: Wendler Silke
Published: July 2005

Kuckucksnestlinge sind darauf bedacht, das einzige Küken im Nest zu sein. Kaum sind sie aus dem Ei geschlüpft, schieben sie die Eier oder den Nachwuchs ihrer Pflegeeltern aus dem Nest. Damit wollen sie sich die alleinige Aufmerksamkeit ihrer Ernährer sichern. Doch auch das Einzelkükendasein hat seinen Preis: Je weniger Nestlinge eine Brut hat, desto weniger Futter bringen die Vogeleltern herbei. Die Nestlinge des in Südostasien lebenden Fluchtkuckucks (Cuculus fugax) bedienen sich eines optischen Tricks, um zu mehr Futter zu gelangen.
X – Der Girly‐Faktor
Authors: Kronberg Inge
Published: July 2005

Nach dem Y‐Chromosom gilt nun auch das X‐Chromosom des Menschen als entschlüsselt – allein die Liste der beteiligten Wissenschaftler füllt eine halbe Druckseite. Etwa 1000 Gene liegen auf dem X‐Chromosom, die Gendichte ist damit geringer als bei Autosomen. Überraschend viele Gene des X‐Chromosoms codieren für Proteine, die mit der Gehirnfunktion zu tun haben oder sie sind im Hoden und in Krebszellen aktiv. Die Sequenzierung des X‐Chromosoms könnte der Schlüssel zum Verständnis der Human‐Evolution sein und hat die Diskussion um genetisch bedingte Unterschiede zwischen Mann und Frau neu belebt.
Anzucht infektiöser Hepatitis C‐Viren im Labor
Authors: Irsch Wilhelm
Published: July 2005

Mit Hilfe eines neuen Zellsystems gelang es erstmals im Labor, Hepatitis C‐Viren (HCV) zu vermehren. Damit wurde die Voraussetzung dafür geschaffen, Medikamente und Impfstoffe gegen das Virus zu entwickeln, das eine schleichende, oft tödlich endende Entzündung der Leber (Hepatitis) hervorruft. Dies gilt als ein Meilenstein in der Erforschung von Hepatitis C und im Kampf gegen die stille Seuche.