bluuebunny/crossref_metadata_2025 huggingface dataset:
A Photoelectrochemical Investigation of the n‐Semiconductors α‐HgS and α‐HgS1‐xSex Solid Solutions
Authors: Repenning D. , Sprünken H.‐R. , Schindler R. N.
Published: July 2012

Photoclectrochemical investigations are described with solid solution HgS1‐xSex electrodes of the compositions x = 0, 0.01, 0.03, and 0.06. The electrodes were prepared by a sublimation and a vapor phase technique, respectively. The semiconductor electrodes were characterized by their current‐potential dependence and their spectral response as function of illumination time.—No corrosion currents were observed in an aqueous electrolyte of pH 2.5 in the potential vs. SCE region −0.45 to +0.9 V in the dark. Upon illumination only the electrode with the highest selenium content corrodes noticeably. Bandgaps of Eg = 2.1 eV with x = 0 and Eg = 1.7 eV with x = 0.06 are determined from wavelength dependent photocurrent spectra. The results indicate that the transition of the hexagonal α‐ to the cubic β‐structure is more hindered in the solid solution electrodes than in the pure α‐HgS system.
Kinetics of Phase Separation in Binary Lutidine/Water Mixtures Using a Fast Temperature Jump Technique
Authors: Strey R. , Wagner J. , Woermann D.
Published: July 2012

Temperature jump experiments with a characteristic heating time of 0.5 ms are carried out with lutidine/water mixtures of off‐critical composition. The system is brought from an equilibrium state in the one fluid phase region into a metastable state in which formation of a second fluid phase occurs. The temperature jumps are produced by discharging a high voltage capacitor through the electrically conducting sample.—The light intensity scattered by the sample at an scattering angle of 90° is monitored as function of time after triggering the temperature jump. The scattering intensity versus time curves show consecutive maxima. They can be interpreted by Mie‐scattering of growing droplets of the new emerging phase. The growth rate is calculated as function of the overheating temperature and supersaturation respectively. The data indicate diffusion controlled growth. — The experimentally determined upper and lower limits of metastability are discussed in terms of the classical (Becker‐Döring) nucleation theory and the Langer‐Turski model of nucleation.
Kinetics of the Reaction NH2 + 1,3‐Butadiene
Authors: Hack W. , Schröter M. R. , Gg. Wagner H.
Published: July 2012

The gas‐phase reaction of free NH2 radicals with 1,3‐butadiene has been investigated in an isothermal discharge‐flow system under pseudo‐first‐order conditions. NH2 was produced in the fast reaction to fluorine atoms with ammonia and its concentration was monitored by laser‐induced fluorescence. For the room temperature measurements at 2 mbar a rate coefficient of 6.7 · 109 cm3 mol−1 s−1 was derived. Temperature and pressure conditions were varied in the range of 230–360 K, and 2–10 mbar, respectively. The temperature dependence can be described in the Arrhenius expression k(T) = 3.8 · 1011 exp(‐1140 K/T) cm3 mol−1 s−1. An effect of the total pressure on the rate constant was not observed.
Polarized Absorption Spectrum of Biphenylene: The Origin of the Intensity of the First Band System and the Vibrational Analysis for the Second Band System
Authors: Hoshi Toshihiko , Yamamoto Hiromasa , Miyauchi Toru , Mori Shoji , Kobayashi Michio , Tanizaki Yoshie
Published: July 2012

A polarized absorption spectrum of biphenylene was measured at a low temperature using a stretched polymer film technique. The polarizations of the bands positioned at 253 and 200 nm were determined to be long‐axis and short‐axis polarized, respectively. A mechanism is proposed in which the intensity of the first symmetry forbidden band system is induced merely by coupling with the vibration of a b2u skeletal deformation without borrowing the intensity from the nearby band. The vibrational analysis for the second band system was also examined in views of the polarized spectrum using the stretched polymer film.
Recent Developments in Transition State Theory
Authors: Pechukas Philip
Published: July 2012

A number of recent developments in classical and quantum transition state rate theory are briefly discussed.
Molecular Beam Studies of Bimolecular Reactions: F + H2 and Li + HF
Authors: Lee Yuan T.
Published: July 2012

Using reactions of F + H2 → HF + H and Li + HF → LiF + H as examples, the application of the crossed molecular beams method in the investigation of dynamics of bimolecular chemical reactions is described. Most of the discussions are centered on the angular distributions of reaction products and their implication to the relation between potential energy surface and reaction dynamics.
H3 and H3+: Correlations of Theory and Experiment
Authors: Porter Richard N.
Published: July 2012

A survey of calculations of the properties of H3 and H3+ with particular emphasis on those in which the author has been involved is given. Correlations with hot‐atom experiments and spectroscopic observations are discussed. A preview of new work on the predissociation of quasistable upper‐sheet Jahn‐Teller states of H3 is presented.
Reactive Scattering Studies on Oriented Molecules
Authors: Stolte Steven
Published: July 2012

The state of the art of reactive scattering with oriented molecules is presented. The alignment and orientation achieved with laser methods and deflection fields are compared to each other. They can be described very well with a short Legendre series. The steric reactive scattering phenomena turn out to be large and are closely connected to the configuration of the transition state. In a few cases a deconvolution to a steric reaction probability function can be carried out. The concept of azimuthal steric dependence is introduced.
Stochastic Trajectory Studies of Chemical Processes at Surfaces
Authors: Tully John C. , Muhlhausen Carl W. , Ruby Leah R.
Published: July 2012

Classical trajectory studies have been carried out of the dynamics of simple chemical processes at surfaces. Empirical potential energy hyper‐surfaces were employed. The motion of only a few (5 or 6) atoms in the immediate vicinity of the reactive event was followed explicitly. The effects of the remaining surface and bulk atoms were replaced by friction and random forces (with memory), constructed from experimental phonon spectra. Among the systems studied are inelastic scattering of N2 from Ag(111), and recombination of O with C on Pt(111). Particular attention was paid to the mechanisms of energy transfer and to the specificity of energy disposal in surface reactions.
Cyanine Dyes as Sensitizers of the Photopolymerization of Diacetylenes in Multilayers
Authors: Bubeck C. , Tieke B. , Wegner G.
Published: July 2012

Multilayers of amphiphilic diacetylene fatty acids are prepared following the method of Langmuir and Blodgett. The photopolymerization of the diacetylene units can be sensitized for visible light by surface active cyanine dyes embedded in the multilayers. Using optical spectroscopy a high polymer yield is found. The yield is independent of the spectral range of the absorption and the concentration of the dyes, respectively, in the range between 0.02 and 3 mole percent. ‐ The quantum yield of the sensitized photopolymerization is low: the dye molecule must absorb about 1000 photons to sensitize the reaction of one monomer molecule. The fluorescence of the dyes is already quenched at low conversion. The origin is an energy‐ and electron transfer to the oligomer chain.
Rotational and Vibrational Relaxation in the Degenerate Vibrationsv24andv21of Cyclohexane in the Liquid State
Authors: Bien T. , Düge G.
Published: July 2012

Correlation functions ϕ(t) and correlation times were obtained by Fourier transformation of the degenerate fundamental bandsv24andv21of liquid cyclohexane. Reorientational correlation functions were calculated based on the Kubo line shape theory in order to extract the contribution of vibrational relaxation. Dephasing caused by short range interactions is a possible mechanism for vibrational relaxation at least forv21.
An NMR Study of the Dynamics of the Schlenk Equilibrium of 2‐Methylpropylmagnesium Bromide in Tetrahydrofuran
Authors: Allen Peter E. M. , Hagias Stan , Lincoln Stephen F. , Mair Clyde , Williams Evan H.
Published: July 2012

A 90 MHz proton NMR determination of the activation and thermodynamic parameters of the Schlenk equilibrium of 2‐methylpropylmagnesium bromide in tetrahydrofuran is reported. The entropy of activation is consistent with bimolecular reactions of unassociated species proceeding through a transition state resembling a mixed‐bridge dimer. The quantitative data confirm accepted concepts of the solvation states of the species involved. — Association equilibria were explored in order to ensure that they were insignificant under the conditions of the kinetic measurements on the Schlenk equilibria. — The association of di‐2‐methylpropylmagnesium is strongly concentration‐dependent but almost temperature‐independent. The exchange rate is too slow to be measured by NMR methods and much slower than the Schlenk equilibrium. The associates are either cyclic or cluster compounds, or, if linear, have an average degree of polymerization of 10. — The field positions of the resonances of RMgBr and R2Mg reverse at low temperature.
Charge Transfer from the Solvent Radical Cation to Solutes Studied in Pulse‐Irradiated Liquid n‐Butyl Chloride
Authors: Mehnert R. , Brede O. , Naumann W.
Published: July 2012

Charge transfer from n‐butyl chloride radical cations (BuCl+) to 11 solutes (S) (alkanes, alkenes, aromatics, and amines) was studied by pulse radiolysis. Using a mechanism proposed for radiation‐induced ionic processes in liquid n‐butyl chloride the rate constants of the reaction

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were determined. At gas phase ionization potential differences ΔI = (IBuCl‐Is) smaller than 1.5 eV the rate constants increased rapidly with increasing ΔI and reached for larger ΔI nearly constant values of about 1010 dm3 mol−1 s−1. The dependence of the rate constants on the ionization potential differences k vs. ΔI is explained in terms of a two‐step process consisting of migration of solvent cations and electron transfer from the solute molecule to the solvent cation. The probability of the last step was calculated using the Franck‐Condon principle. In the framework of a simplified model taking into account vibrational stretching and deformation modes of the reactants and solvent modes in thermally averaged form a reasonable fit of the k vs. ΔI behaviour was obtained.
The Magnetic Susceptibility of Molten Bi — BiCl3, In — InCl3, and In — InBr3 Solutions
Authors: Itoh T. , Tashiro Y. , Uemura O. , Satow T.
Published: July 2012

Measurements of the magnetic susceptibility for Bi — BiCl3, In — InCl3, and In — InBr3 systems in the liquid state were made over a wide composition range. Total diamagnetic susceptibilities of molten Bi — BiCl3 system decrease with increasing temperature. On the other hand, little change of the susceptibility was observed against temperature in both molten In systems. Composition dependences of the magnetic susceptibility indicate that apparent paramagnetic contributions exist both in the metal rich and in the salt rich regions of the molten Bi — BiCl3 system, while an extreme electron localization occurs in the composition range between pure salt and 66.7 mol‐% In in the molten In systems. The valency of existing ions and the degree of electron localization are discussed using these experimental results.
Kinetics of the Species OH(A2Σ+), OH(X2Π and CH(X2Π) in the System C2H2/O/H
Authors: Grebe J. , Homann K. H.
Published: July 2012

OH*(A 2Σ+) and OH(X2Π) concentration‐time‐profiles were measured in the gas phase reaction system C2H2/O/H at 2.66 mbar and 298 K in a discharge flow system for largely varying initial conditions. The well established chemiluminescence reaction CH + O2 → OH*(A2Σ+) + CO connects the experimental OH*(A2Σ+) concentrations to the concentrations of the intermediate CH(X 2Π) which is an important precursor of higher hydrocarbons. Computer analysis showed that the reaction CH2 + H → CH + H2 is the major CH formation reaction with a rate constant k4 of about 5 · 1013 cm3 mol−1 s−1. Reaction CH2 + O → CH + OH does not contribute significantly to either CH or OH formation. A rate constant k28 = 4.8 · 1010 cm3 mol−1 s−1 was obtained.
Micellisation Processes in Concentrated Sodium Deoxycholate Solutions – Effect of Different Counterions
Authors: Sesta B. , La Mesa C. , Bonincontro A. , Cametti C. , Di Biasio A.
Published: July 2012

The effect of different electrolytes (NaBr, CsBr, Bu4NBr) on the micellisation processes of Sodium Deoxycholate solutions has been studied by means of various experimental techniques (densimetric, viscometric and microwave dielectric measurements) in the concentration range above the first critical micelle concentration. The size and shape of the secondary micelles are estimated and the role of the interfacial water in these aggregation processes discussed.
Neuere Untersuchungen zur Bindung von Ethidiumbromid an DNA 4. Mitteilung: Betain B
Authors: Roding Joachim , Zimmermann Herbert W.
Published: July 2012

Betaine B (8‐amino‐5‐ethyl‐3‐oxido‐6‐phenylphenanthridinium‐betaine) is bound to DNA as protonated cation BH⊕ (8‐amino‐5‐ethyl‐3‐hydroxy‐6‐phenylphenanthridinium‐cation). BH⊕ is a hydroxy derivative of the ethidium cation E. Its binding to calf thymus DNA has been investigated by means of absorption spectroscopy. From binding isotherms we determined the binding constants of the non‐competitive binding (intercalation) K1 = 0.9 · 104 M−1 and the competitive binding (external binding) K2 = 1.0 · 106 M−1 using NaCl as competitor, T = 298 K. The constant K1 of the intercalation is much more smaller than the constant K2 of the external binding. Similar properties has the ethidium cation E. – Unprotonated betaine B isn't bound to DNA. In a range of middle pH‐values there exists an equilibrium in solution between the free unprotonated betaine B and the protonated bound betaine BH⊕. The free enthalpy of binding of BH⊕ to DNA forces the protonation of the base B.
The Viscosity of Carbon‐Monoxide and its Mixtures with Other Gases in the Temperature Range 25 – 200°C
Authors: Kestin J. , Ro S. T. , Wakeham W. A.
Published: July 2012

The paper reports new, absolute measurements of the viscosity of carbon monoxide, nitrogen, of two of their binary mixtures, and of mixtures of carbon monoxide with helium, neon and argon. The measurements have been carried out in an oscillating disk viscometer at a pressure of 0.1 MPa in the temperature range 25 – 200°C. The accuracy of the absolute viscosities reported is estimated to lie between ±0.1 and ±0.2%. The measurements have been conducted in such a way that the ratios of the viscosity of carbon‐monoxide and its mixtures with nitrogen to that of pure nitrogen were determined directly with an uncertainty of no more than ±0.1%. The viscosity ratios are found to depart from unity by no more than this uncertainty over the entire temperature range studied. – The viscosity data for all of the systems studied have been correlated, within their experimental error, by means of the extended law of corresponding states. The experimental results have been employed to derive binary diffusion coefficients of the gas mixtures. In the particular cases of CO – He and CO – Ar, the experimental data have also been used to examine the kinetic theory description of the results of recent measurements of the thermal conductivity at low and moderate density and near room temperature.
Diatomic Molecule Electronic Structure beyond Simple Molecular Constants
Authors: Field Robert W.
Published: July 2012

Molecules with partly filled 3d or 4f shells have a surprisingly large number of low lying electronic states, resulting in incredibly complex spectra. This paper attempts to show that, although the spectra are complicated, the explanation of the global electronic structure is quite simple. Ligand Field Theory displays all of the important relationship between the dN or fN structures in the free‐atomic‐ion and the molecule. The splitting of the core into numerous substates causes a gratuitous repetition and intermingling of the usual ϱ, π‐valence structures which are so familiar for molecules with filled‐shell cores. The 4f electron is shown to be a useful probe of the unknown structures of more diffuse valence orbitals. A semi‐empirical theory is described which allows important features of the molecular level diagram to be predicted using atomic energy level tables and a scrap of paper. The same theory provides a basis for detailed numerical parametrization and quantitative predictions of energy levels, perturbation matrix elements, hfs splittings, and transition intensities.
Molecular Orbital Theories and the Structural Properties of Molecules
Authors: Pople J. A.
Published: July 2012

The use of theoretical models in predictions of equilibrium geometries of molecules is reviewed. If the basis set is taken to the split‐valence + polarization level and if the electron is included by Møller‐Plesset perturbation theory to third order, theoretical structures are found to lie within experimental error ranges for the majority of small molecules that have been investigated. The application of the same techniques to unstable intermediates is illustrated by some studies on the vinylidene‐acetylene rearrangement.
Laser Spectroscopy of Iodine Monofluoride Produced in Situ in a Molecular Beam Experiment
Authors: Trautmann M. , Trickl T. , Wanner J.
Published: July 2012

Nascent IF molecules in various vibrational‐rotational manifolds of the electronic ground state have been prepared in a molecular beam experiment. High‐resolution laser spectroscopy has been applied to determine accurate band head positions and band origins of the B→X transition. Dunham coefficients have been calculated for the X1Σ+ and B3Π(O+) states. The hyperfine structure of the rotational lines has been observed.
Molecular Ions Formed by Field Ionization
Authors: Block J. H.
Published: July 2012

The formation of ions in high electric fields in front of field emitters is investigated by mass spectrometry and appearance spectroscopy. The combination of these methods provides information on ion generating processes and molecular properties in high electric fields. For noble gases ionization potentials are determined, for hydrogen (H+, H2+, H3+) detailed information is given for ionization, field‐induced dissociation, and surface interaction (H3+). Protonated rare gas molecular ions are formed by a fast adiabatic proton stripping, without reflecting values of proton affinities in appearance energies. Field‐induced surface reactions form sulfur chains (Sx, x ≦ 22) from S2 molecules, while ring structures (Sx, with x = 8 most abundant) predominate when field pulse desorption with zero reaction field is applied. Cluster‐ions with low internal binding energy (like (H2O)n · H+, n ≦ 12) are formed at low temperatures and by using photon‐induced field desorption.
Energy Levels for Photoinjection of Excess Electrons into Ammonia Vapor at Various Densities — The Transition from the Quasi‐Free to the Localized Electron State
Authors: Krebs P. , Bukowski K. , Giraud V. , Heintze M.
Published: July 2012

The energy of the electronic levels in ammonia vapor which are populated by the photoinjection of excess electrons has been determined in the density range from 1.7 · 1017 to 2.3 . 1021 molecules/cm3 at T = 400 K. The method used is based on measuring the photoelectric work function of a stainless steel photocathode immersed in ammonia vapor with respect to that into vacuum. From these measurements the chemical potential of two bands of electron injection levels can be elucidated. These results are discussed together with electron mobilities which show with increasing vapor density a transition from the quasi‐free to the localized electron state. It will be shown that the onset of electron localization obeys Mott's criterion for quantum localization. From these results together with the optical absorption spectra of solvated electrons, and from theoretical considerations it follows that one of the injection bands is the conduction band. The other one is formed by pre‐existing solvent traps. Therefore, in contrast to the conventional assumption in the theory of photoemission, the electron injection into polar media does not occur only in the conduction band but also in pre‐existing trap states (band‐tail states) thus supporting Thompson's recent assertion. This requires the reinterpretation of existing data on photoemission of electrons into polar solvents (electrolytes) including the photoionization of solute molecules in polar solvents in order to determine the bottom of the conduction band V0.
Molecular Motions and Phase Transitions in [(CH3)4N]2MBr6 (M: Pt, Te, Sn). A Proton Magnetic Relaxation, Differential Thermal Analysis, and Powder X‐Ray Diffraction Study
Authors: Sato Setsuko , Ikeda Ryuichi , Nakamura Daiyu
Published: July 2012

The measurements of the temperature dependences of the proton spin‐lattice relaxation time T1 and of the second moment of proton NMR absorptions as well as the experiments of DTA and X‐ray powder diffraction were carried out in tetramethylammonium(tetMA) hexabromo‐platinate(IV),‐tellurate(IV), and ‐stannate(IV). From the DTA experiments, various phases were found for (tetMA)2PtBr6 while three phases for both of the remaining complexes. At room temperature, the three complexes crystallize with the Fd3c cubic structure, while they form the Fm3m type cubic crystals in their highest‐temperature phase. The lattice constants of each complex in both of these phases were determined. The second moment study revealed that the reorientational motions of the cations in these complexes freeze for the most part at nearly the same temperature, but a small fraction of the motional freedom still remains even at 77 K. A broad and also deep T1 minimum accompanied by a shallow one on the low‐temperature side was obtained in the T1 measurements of all of these complexes. The broad T1 minimum can be attributed to both of the C3 reorientation of the four methyl groups and the isotropic reorientation of the cation, while the shallow one to a small‐angle reorientation of the methyl groups about their respective C3 axes through the all‐staggered conformation of the cation. The activation energies were evaluated for various motional modes detected.
Automatic segmentation and supervised learning‐based selection of nuclei in cancer tissue images
Authors: Nandy Kaustav , Gudla Prabhakar R. , Amundsen Ryan , Meaburn Karen J. , Misteli Tom , Lockett Stephen J.
Published: July 2012

Analysis of preferential localization of certain genes within the cell nuclei is emerging as a new technique for the diagnosis of breast cancer. Quantitation requires accurate segmentation of 100–200 cell nuclei in each tissue section to draw a statistically significant result. Thus, for large‐scale analysis, manual processing is too time consuming and subjective. Fortuitously, acquired images generally contain many more nuclei than are needed for analysis. Therefore, we developed an integrated workflow that selects, following automatic segmentation, a subpopulation of accurately delineated nuclei for positioning of fluorescence in situ hybridization‐labeled genes of interest. Segmentation was performed by a multistage watershed‐based algorithm and screening by an artificial neural network‐based pattern recognition engine. The performance of the workflow was quantified in terms of the fraction of automatically selected nuclei that were visually confirmed as well segmented and by the boundary accuracy of the well‐segmented nuclei relative to a 2D dynamic programming‐based reference segmentation method. Application of the method was demonstrated for discriminating normal and cancerous breast tissue sections based on the differential positioning of the HES5 gene. Automatic results agreed with manual analysis in 11 out of 14 cancers, all four normal cases, and all five noncancerous breast disease cases, thus showing the accuracy and robustness of the proposed approach. © Published 2012 Wiley Periodicals, Inc.
Investigation into the experimental protocols required to determine maximum residue limits (MRLs) in honey
Authors: Fussell Richard J. , Heinrich Katharina , Dickinson Michael , Wilkins Selwyn , Roelofs Victoria , Murray Alistair , Kay Jack F. , Sharman Matthew
Published: July 2012

There is current debate within the EU, and internationally, on how withdrawal periods and maximum residue limits (MRLs) may be set for honey production. Whilst comprehensive EU guidelines exist for calculating the withdrawal times of veterinary medicines in most food‐producing species, the analytical variables to be studied for bees/honey are not well defined. The objective of this study was therefore to investigate and understand the factors, for example sampling variability, that is important in the development of a harmonized protocol that can be used to generate the robust scientific data necessary to assist risk assessors in proposing MRLs for honey.

Ten bee colonies were treated in the spring with a model compound (ciprofloxacin). One hive was used to study intra‐hive variation in residue concentrations and the other nine were used in an inter‐hive study over a 41‐week sampling period. All samples were analyzed using liquid chromatography‐tandem mass spectrometry (LC‐MS/MS). The highest mean concentration from nine hives used in the inter‐hive study was 4627 µg/kg eight days (D8) after treatment. The concentration of ciprofloxacin declined to an average concentration of 1756 µg/kg at D30 and 733 µg/kg at D283 (over‐winter sample). A generalized additive model was used to fit a smooth curve for trend estimation. For some individual hives the concentration of ciprofloxacin increased slightly at the later sampling time‐points. Consequently it was not possible to interpolate, with confidence, a finite withdrawal period for ciprofloxacin at theoretical MRLs between 25 and 500 µg/kg. The observed variation in concentration of ciprofloxacin between hives indicates that the validity of the EU guideline for bees/honey, which requires five samples from five hives to calculate a withdrawal period, may require revision. © 2012 Crown copyright. Drug Testing and Analysis © 2012 John Wiley & Sons, Ltd.
Microscopic Origin for Multistability in a Photomagnetic CoFe Prussian Blue Analogue
Authors: Lejeune Julien , Cafun Jean‐Daniel , Fornasieri Giulia , Brubach Jean‐Blaise , Creff Gaëlle , Roy Pascale , Bleuzen Anne
Published: July 2012

Switchable compounds attract growing interest, as they offer promising perspectives for high‐density storage applications. Much effort has been invested in understanding the mechanisms involved in such properties, in order to prepare systems that are suitable for real applications. Compounds exhibiting an electronic transition that can be triggered by an external stimulus have been extensively studied. While most studies describe the switching properties of such systems in terms of a two‐state model, the existence of multistability in switchable systems remains a controversial topic. In thispaper, we compare the thermally populated CoIIFeIII and photoinduced (CoIIFeIII)* states of the Na2Co4[Fe(CN)6]3.3·14H2O Prussian blue analogue. The comparison of the infrared spectroscopic data for the two CoIIFeIII and (CoIIFeIII)* states shows differences at a microscopic scale that cannot be explained in terms of a two‐state model. These experimental data suggest a change in the coordination sphere of the sodium cation, which strongly supports a displacement of the sodium cation in the lattice between the two states. This direct evidence of several distinct CoFe states at an atomic level in this system highlights a new kind of multistability involving competitive metal‐to‐ligand interactions in a switchable compound.
Precise, fast, and flexible determination of protein interactions by affinity capillary electrophoresis: Part 1: Performance
Authors: Redweik Sabine , Xu Yuanhong , Wätzig Hermann
Published: July 2012

A generic screening approach was performed to investigate the binding of various potential ligands to proteins in order to investigate how proteins interact with ions and the complete surrounding solution. This also allows to study binding behavior and its regulation and protein functionality in general in a native environment. The ACE technique affords an excellent precision by applying appropriate rinsing procedures using a pressure of 2.5 bar and a continuous flow concept. Confidence intervals were estimated to proof significance of the interactions. This enables to investigate smaller yet important interactions, which were not possible with less precise techniques before. The influence of various ions on ovalbumin, β‐lactoglobulin, and BSA were screened by comparing the mobility ratios of the free protein and the influenced one. The analysis was performed using the metal ions Ba2+, Ca2+, Cu2+, Mg2+, Mn2+, Ni2+, the pharmaceutical cations ephedrine hydrochloride, ethambutol dihydrochloride, pilocarpine hydrochloride and pirenzepine dihydrochloride, and various anions, in particular phosphate, acetate, succinate, glutamate, and salicylate. For the anion influence study, myoglobin was also included to the screened proteins. The influence of these ions on the proteins was well diversified. The interactions could be distinguished with a fast and precise screening method since 90% of all mobility ratios had a RSD% below 2% and 79% had a RSD% lower than 1%. Hence, for more than 75% of the protein–ligand pairs significant interactions are observed with a very small confidence interval due to the very excellent precision of these used method.
Optical microflow cytometer based on external total reflection
Authors: Fu Lung‐Ming , Wang Yao‐Nan
Published: July 2012

A novel optical microflow cytometer based on external total reflection comprising a laser‐induced fluorescence system, a PDMS chip, a plane mirror and a dichroic beamsplitter is proposed for the simultaneous detection, enumeration and sizing of labeled and nonlabeled microparticles. In the proposed approach, the total number and size of the particles passing through the detection region is determined via the nonscattered light signal reflected from a plane mirror positioned over the microchip, while the number of fluorescence‐labeled particles is determined via the back scattered fluorescence signal. The experimental results confirm the ability of the proposed system to count and size fluorescent and nonfluorescent particles with nominal diameters ranging from 6 to 10.2 μm. In addition, it is shown that for a mixed sample containing both labeled and nonlabeled particles, the number of nonlabeled particles can be determined by subtracting the number of peaks in the fluorescence signal from that in the reflected light signal.
Novel covalently coated diazoresin/polyvinyl alcohol capillary column for the analysis of proteins by capillary electrophoresis
Authors: Yu Bing , Liu Peng , Cong Hailin , Tang Jianguo , Zhang Lixin
Published: July 2012

A novel method for the preparation of covalently linked capillary coatings of PVA was demonstrated using photosensitive diazoresin (DR) as coupling agents. Layer‐by‐layer self‐assembly film of DR and PVA based on hydrogen bonding was first fabricated on the inner wall of capillary, then the hydrogen bonding was converted into covalent bonding after treatment with UV light through the unique photochemistry reaction of DR. The covalently bonded coatings suppressed basic protein adsorption on the inner surface of capillary, and thus a baseline separation of lysozyme, cytochrome c and BSA was achieved using CE. Compared with bare capillary or noncovalently bonded DR/PVA coatings, the covalently linked DR/PVA capillary coatings not only improved the CE separation performance for proteins, but also exhibited good stability and repeatability. Due to the replacement of highly toxic and moisture‐sensitive silane coupling agent by DR in the covalent coating preparation, this method may provide a green and easy way to make the covalently coated capillaries for CE.
Trenbolone causes mortality and altered sexual differentiation in Xenopus tropicalis during larval development
Authors: Olmstead Allen W. , Kosian Patricia A. , Johnson Rodney , Blackshear Pamela E. , Haselman Jonathan , Blanksma Chad , Korte Joseph J. , Holcombe Gary W. , Burgess Emily , Lindberg-Livingston Annelie , Bennett Blake A. , Woodis Kacie K. , Degitz Sigmund J.
Published: July 2012

Trenbolone is an androgen agonist used in cattle production and has been measured in aquatic systems associated with concentrated animal-feeding operations. In this study, the authors characterized the effects of aqueous exposure to 17β-trenbolone during larval Xenopus tropicalis development. Trenbolone exposure resulted in increased mortality of post-Nieuwkoop–Faber stage 58 tadpoles at concentrations ≥100 ng/L. Morphological observations and the timing of this mortality are consistent with hypertrophy of the larynx. Development of nuptial pads, a male secondary sex characteristic, was induced in tadpoles of both sexes at 100 ng/L. Effects on time to complete metamorphosis or body sizes were not observed; however, grow-outs placed in clean media for six weeks were significantly smaller in body size at 78 ng/L. Effects on sex ratios were equivocal, with the first experiment showing a significant shift in sex ratio toward males at 78 ng/L. In the second experiment, no significant effects were observed up to 100 ng/L, although overall sex ratios were similar. Histological assessment of gonads at metamorphosis showed half with normal male phenotypes and half that possessed a mixed-sex phenotype at 100 ng/L. Hypertrophy of the Wolffian ducts was also observed at this concentration. These results indicate that larval 17β-trenbolone exposure results in effects down to 78 ng/L, illustrating potential effects from exposure to androgenic compounds in anurans. Environ. Toxicol. Chem. 2012; 31: 2391–2398. © 2012 SETAC
Associations of insulin‐like growth factor and insulin‐like growth factor binding protein‐3 with mortality in women with breast cancer
Authors: Duggan Catherine , Wang Ching‐Yun , Neuhouser Marian L. , Xiao Liren , Smith Ashley Wilder , Reding Kerryn W. , Baumgartner Richard N. , Baumgartner Kathy B. , Bernstein Leslie , Ballard‐Barbash Rachel , McTiernan Anne
Published: July 2012

Elevated circulating insulin‐like growth factor‐1 (IGF‐1), a breast epithelial cell mitogen, is associated with breast cancer development. However, its association with breast cancer survival is not established. Circulating concentrations of IGF‐1 are controlledviabinding proteins, including IGF Binding Protein‐3 (IGFBP‐3), that may modulate the association of IGF‐1 with breast‐cancer outcomes. We measured IGF‐1 and IGFBP‐3 concentrations in serum from 600 women enrolled in the health, eating, activity, and lifestyle (HEAL) study, a multiethnic, prospective cohort study of women diagnosed with stage I‐IIIA breast cancer. We evaluated the association between IGF‐1 and IGFBP‐3, and as a ratio, modeled using quintile cut‐points, with risk of breast cancer‐specific (n= 42 deaths) and all‐cause mortality (n= 87 deaths) using Cox proportional hazards models. In models adjusted for body mass index, ethnicity, tamoxifen use at time of blood draw, treatment received at diagnosis and IGFBP‐3, women in the highest quintile of IGF‐1 level had an increased risk of all‐cause mortality (Hazard Ratio (HR) = 3.10, 95% CI 1.21–7.93,p= 0.02), although no dose‐response association was evident. The IGF‐1/IGFBP‐3 ratio, an indicator of free IGF‐I levels, was significantly associated with increasing risk of all‐cause mortality (HR = 2.83, 95% CI 1.25–6.36ptrend= 0.01, uppervs. lower quintile) in a fully adjusted model. In conclusion, high serum levels of IGF‐1 and the IGF‐1/IGFBP‐3 ratio were associated with increased risk of all‐cause mortality in women with breast cancer. These results need to be confirmed in larger breast cancer survivor cohorts.
Effects of an Ostracod (Cypris pubera) on the Rotifer Keratella tropica: Predation and Reduced Spine Development
Authors: Gilbert John J.
Published: July 2012

This study investigates two different effects of an ostracod on a rotifer. The rotifer Keratella tropica and the ostracod Cypris pubera were cultured on the alga Cryptomonas erosa. Adult ostracods (2.2 mm body length) significantly reduced the population growth rate (r day–1) of K. tropica from 0.42 to 0.13. Individuals of this size ingested live rotifers and produced fecal pellets with rotifer loricas. Smaller ostracods (both 0.59 and 1.61 mm body lengths) did not affect K. tropica 's population growth rate. Surprisingly, C. pubera significantly inhibited spine development in K. tropica. Rotifers cultured with juvenile, non‐predatory ostracods had similar lorica lengths but right and left posterior spines that were 10 and 30% shorter, respectively. The spine reduction induced by the ostracod kairomone is in striking contrast to the spine elongation induced in this rotifer by kairomones from copepods, cladocerans and Asplanchna. In shallow ecosystems, large ostracods that swim in the plankton may be important predators of rotifers. In addition, the presence of ostracods in plankton communities may be one of many factors affecting rotifer spine development. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Involvement of the adrenal glands and testis in gap junction formation via testosterone within the male rat anterior pituitary gland
Authors: Sakuma Eisuke , Wada Ikuo , Otsuka Takanobu , Wakabayashi Kenjiro , Ito Kinya , Soji Tsuyoshi , Herbert Damon C.
Published: July 2012

We investigated the influence of testicular and adrenal androgens on the presence of gap junctions between folliculo‐stellate cells in the anterior pituitary glands of 60‐day‐old Wistar‐Imamichi strain male rats. The animals were separated into six groups: Group A served as the controls and had free access to a normal diet and water, Group B was given a normal diet and 0.9% NaCl for their drinking water as the controls of adrenalectomized groups, Group C was castrated, Group D was adrenalectomized, Group E was both castrated and adrenalectomized, and Group F was also both castrated and adrenalectomized. In addition, the animals of Group F were administered a dose of testosterone that is known to produce high physiological levels of the hormones in plasma. Five rats from each group were sacrificed 1, 2, 3, 4, 5, 6, and 7 days after their respective operation, and the anterior pituitary glands were removed and prepared for observation by transmission electron microscopy. We quantified the number of follicles and gap junctions and calculated the rate of occurrence as the ratio of the number of gap junctions existing between folliculo‐stellate cells per intersected follicle profile. Simultaneous removal of adrenal glands with castration resulted in a significantly decrease in the number of gap junctions, whereas the administration of testosterone to these rats compensated for this change. These observations indicate that the preservation of gap junctions between folliculo‐stellate cells is mainly dependent on androgens from both the testes and adrenal glands in adult male rats. Microsc. Res. Tech., 2012. © 2012 Wiley Periodicals, Inc.
Clinical and molecular effects on mature burn scars after treatment with a fractional CO2 laser
Authors: Qu Le , Liu Austin , Zhou Li , He Chundi , Grossman Peter H. , Moy Ronald L. , Mi Qing‐Sheng , Ozog David
Published: July 2012

Background and Objective

There have been several case reports of improvement in the appearance of mature burn scars following treatment with fractional CO2 lasers. However, the biochemical mechanisms responsible for these improvements have not been elucidated.

Materials and Methods

Ten patients with mature, full‐thickness, hypertrophic burn scars received initial treatment with a fractional CO2 laser. Clinical improvement was measured with Vancouver Scar Scale as well as Patient and Observer Scar Assessment Scale. Fresh tissue samples were obtained before the initial treatment and 48 hours after the first treatment for TaqMan Real‐time RT‐PCR analyses. Expressions of several scar‐related biological markers, including types I and III procollagen, matrix metalloproteinase (MMP)‐1, ‐13, transforming growth factor (TGF)‐β1, β2, β3, and basic fibroblast growth factor (bFGF), as well as microRNA miR‐17‐92 cluster, were investigated.

Results

There were significant improvements in both observer and subject ratings in all scales. Both types I and III procollagen mRNA levels were dramatically down‐regulated after treatment, but the ratio of types I/III procollagen mRNA was not different. The expression of MMP‐1 was significantly up‐regulated after treatment, while TGF‐β2, ‐β3, and bFGF levels were significantly down‐regulated. Expression of miR‐18a and miR‐19a were dramatically up‐regulated (P < 0.05) after treatment.

Conclusions

Our study indicated that fractional CO2 resulted in clinical improvement of mature burn scar. Alteration of types I and III procollagen, MMP‐1, TGF‐β2, ‐β3, bFGF, as well as miRNAs miR‐18a and miR‐19a expression may be responsible for the clinical improvement after treatment. Our finding may have implications for novel treatments and further our understanding of fractional CO2 laser treatment. Lasers Surg. Med. 44: 517–524, 2012. © Wiley Periodicals, Inc.
Analytical Study of Discrete Optical Breathers in Spiral Polymer Chain
Authors: Kovaleva Natalya , Manevitch Leonid
Published: July 2012

Physico‐mechanical properties of polymers in solid state, in particular conditions of their structural transformations, are substantially defined by existence and mobility of elementary nonlinear excitations. The localized oscillatory excitations (breathers), which have been revealed earlier in crystalline polyethylene alongside with topological solitons, turn out to be significant for thermodynamic studies as well as for investigation of energy transfer. We consider analytically the breathers in more complex crystalline polytetrafluoroethylene. It is shown that introduction of adequate variables allows to construct the continuum model describing spatially localized excitations with several internal degrees of freedom. Characteristic parameters of breathers and conditions of their mobility are defined.

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Fixed point theorems of block operator matrices on Banach algebras and an application to functional integral equations
Authors: Kaddachi Najib , Jeribi Aref , Krichen Bilel
Published: July 2012

In this paper, we study some fixed point theorems of a 2 × 2 block operator matrix defined on nonempty bounded closed convex subsets of Banach algebras, where the entries are nonlinear operators. Furthermore, we apply the obtained results to a coupled system of nonlinear equations. Copyright © 2012 John Wiley & Sons, Ltd.
Studies on a damped differential equation with repulsive singularity
Authors: Cheng Zhibo , Ren Jingli
Published: July 2012

By an application of Leray–Schauder alternative principle, existence results of positive periodic solution are presented for a damped differential equation with repulsive singularity. Copyright © 2012 John Wiley & Sons, Ltd.
A cohesive element model for mixed mode loading with frictional contact capability
Authors: Snozzi Leonardo , Molinari Jean‐François
Published: July 2012

We present a model that combines interface debonding and frictional contact. The onset of fracture is explicitly modeled using the well‐known cohesive approach. Whereas the debonding process is controlled by a new extrinsic traction separation law, which accounts for mode mixity, and yields two separate values for energy dissipation in mode I and mode II loading, the impenetrability condition is enforced with a contact algorithm. We resort to the classical law of unilateral contact and Coulomb friction. The contact algorithm is coupled together to the cohesive approach in order to have a continuous transition from crack nucleation to the pure frictional state after complete decohesion. We validate our model by simulating a shear test on a masonry wallette and by reproducing an experimental test on a masonry wall loaded in compression and shear. Copyright © 2012 John Wiley & Sons, Ltd.
First‐trimester prediction of preterm birth using ADAM12, PAPP‐A, uterine artery Doppler, and maternal characteristics
Authors: Goetzinger Katherine R. , Cahill Alison G. , Kemna Janet , Odibo Linda , Macones George A. , Odibo Anthony O.
Published: July 2012

Objective

The objective of this study was to estimate the efficiency of first‐trimester a disintegrin and metalloprotease 12 (ADAM12), pregnancy‐associated plasma protein A (PAPP‐A), uterine artery Doppler, and maternal characteristics in the prediction of preterm birth (PTB).

Methods

This was a prospective cohort study of patients presenting for first‐trimester aneuploidy screening. Maternal serum ADAM12 and PAPP‐A levels were measured by immunoassay, and mean uterine artery Doppler pulsatility indices were calculated. The primary outcome was PTB <34 weeks' gestation, and the secondary outcome was PTB <37 weeks' gestation. Logistic regression was used to model the prediction of PTB using ADAM12, PAPP‐A, uterine artery Doppler, and maternal characteristics, individually and in combination. Sensitivity, specificity, and area under the receiver‐operating characteristic curves were compared between models.

Results

Of 578 patients, 36 (6.2%) delivered <34 weeks, and 78 (13.5%) delivered <37 weeks. For a 20% fixed false positive rate, ADAM12, PAPP‐A, and uterine artery Doppler identified 58%, 52%, and 62% of patients with PTB <34 weeks and 42%, 48%, and 50% of patients with PTB <37 weeks, respectively. Combining these first‐trimester parameters did not improve the predictive efficiency of the models.

Conclusion

First‐trimester ADAM12, PAPP‐A, and uterine artery Doppler are each modestly predictive of PTB; however, combinations of these parameters do not further improve their screening efficiency. © 2012 John Wiley & Sons, Ltd.
Maternal factors associated with misperceptions of the second‐trimester sonogram
Authors: Wong Amy E. , Collingham Justin P. , Koszut Stacey P. , Grobman William A.
Published: July 2012

Objective

Prior studies have shown that patients have poor understanding of prenatal screening tests. The purpose of this study was to evaluate the frequency with which patients have poor understanding of the sensitivity and safety of the second‐trimester fetal sonogram and to identify maternal factors associated with poor understanding.

Method

One hundred fifty‐five women presenting for a routine fetal anatomy scan completed a survey that assessed their understanding of the diagnostic sensitivity and safety of ultrasound, their demographic characteristics, and the sources of information of their knowledge of ultrasound. The frequency of misperception with regard to sonographic sensitivity or safety was determined, and both univariable and multivariable analyses were performed to identify factors associated with misperception.

Results

Fifty‐one percent of women had a misperception of the sensitivity or safety of a second‐trimester sonogram. Although multiple characteristics (age, ethnicity, education, income, source of ultrasound information) were associated with this misperception in univariable analysis, only education and income remained independently associated with misperception in multivariable regression.

Conclusion

Lower educational attainment and lower income are associated with misperception of the sensitivity and safety of a second‐trimester sonogram. © 2012 John Wiley & Sons, Ltd.