bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural Investigations of Electrode Surfaces
Authors: Kolb D. M. 
Published: March 2014

AbstractA survey is given of the various ways in which information on the structure of electrode surfaces and their influence on the electrochemical behavior, especially on adsorption reactions, can be obtained. The techniques now at hand include a wide variety of spectroscopic methods, which are applicable in‐situ, such as reflectance spectroscopy over a broad range of photon energy, second harmonic generation, various X‐ray diffraction techniques and, most recently, scanning tunneling microscopy, which highlights the possibility of acquiring atomic‐scale resolution. In addition, the emersion of electrodes and their subsequent transfer into a vacuum chamber for detailed surface‐structural studies, e.g., by electron diffraction methods, is now widely used in electrochemistry, since it has been shown that electrodes can, in fact, be emersed with their electric double layer apparently intact. The combined venture incorporating all these techniques should lead to a truly microscopic description of electrochemical processes. The way in which structural information, even on an atomic scale, can be derived, is illustrated here by a few selected examples.
Measurement of Mass and Surface Stress at One Electrode of a Quartz Oscillator
Authors: Heusler K. E. , Grzegorzewski A. , Jäckel L. , Pietrucha J. 
Published: March 2014

AbstractThe theory for the calculation of changes of mass and surface stress from frequency measurements at a quartz oscillator subject to different onesided pressures is outlined. The various contributions to apparent changes of the mass are discussed. Experiments refer to the determination of effective molar masses of potassium ions and fluoride ions during electrostatic adsorption and of chemisorbed lead both on polycrystalline gold by a comparison of masses to charges. Effective molar masses of adsorbed species can also be determined by comparison of mass changes to surface concentrations e.g. determined by the radiotracer method as in the example of the adsorption of chloride at the passivating oxide film on iron. The density of very thin films like the passivating oxide film can be obtained by comparing mass changes to thicknesses from optical measurements. In agreement with theoretical expectation, compressive surface stresses were qualitatively found for the underpotential deposition of lead on gold. In the growing oxide film on passive iron very large compressive lateral pressures were observed.
Die Elektrode als Reagens in der organischen Synthese; CC‐Verknüpfungen
Authors: Schäfer Hans J. , Burgbacher Gerd , Schlegel Cornelia , Claus Harald 
Published: March 2014

AbstractThe mechanism of the anodic dimerization of olefins is investigated with the rotating ring‐disc‐electrode. The anodic coupling is applied to the preparation of a morphine derivative. By cathodic addition of organo halides to aldehydes trichloromethylcarbinols, β‐hydroxyesters and cyclopentanoid hydrocarbons become accessible.
The Investigation of the Corrosion of Metal Surfaces, Covered with Thin Electrolyte Layers – A New Experimental Technique
Authors: Stratmann M. , Streckel H. 
Published: March 2014

AbstractIf a metal surface is in contact with an aggressive atmosphere, then thin electrolyte layers are formed on top of the metal surface which may be as thin as a few monolayers of water. – Two techniques are described which allow to analyze the electrochemical processes involved in the corrosion of such a surface: the first technique measures corrosion rates and corrosion potentials as function of the electrolyte thickness without touching the surface under investigation, the second allows to measure polarization curves on metals covered with thin electrolyte layers using a Kelvin probe as reference electrode. Results are discussed which have been obtained with platinum and iron as working electrodes.
Electrochemical Investigations on the Diffusion of Perchlorate Ions in Thin Polypyrrole Layers
Authors: Herberg B. , Pohl J. P. 
Published: March 2014

AbstractThe polypyrrole electrode works as an insertion electrode for anions, e. g. for Perchlorate ions. The kinetics of the electrochemical insertion/dissolution reaction is determined mainly by diffusion processes within the polymer. Using H2O/NaClO4 and CH3CN/LiClO4 electrolytes the chemical diffusion coefficient ΔClO4 of “ClO4” in polypyrrole has been determined by means of potentiostatic and galvanostatic measurements. The values of ΔClO4, are in the range between 10−11 and 10−10cm2s−1; the partial conductivity of ClO4 ions in polypyrrole, calculated from the diffusion coefficient, is by about ten orders of magnitude smaller than the electronic partial conductivity due to electron defects within the polymer.
Influence of Interface Modification on Photoelectrochemical Behaviour of Amorphous Hydrogenated Silicon in Aqueous Electrolytes
Authors: Lewerenz H. J. , Stumper J. 
Published: March 2014

AbstractThe photoelectrochemical behavior of amorphous hydrogenated Si in aqueous electrolytes is investigated. Emphasis is put on competitive processes involving oxidation and depassivation and general possibilities of interface conditioning for modification of electronic properties. Photocurrent transients comparing the behavior of amorphous and crystalline samples are recorded to investigate the dynamics of interfacial processes. At potentials cathodic from flatband, a photoconductive gain effect is observed on a‐Si:H with quantum yields > 10 under appropriate bias and illumination.
Calculation of Osmotic Coefficients of Nonaqueous Electrolyte Solutions with the Help of Chemical Models
Authors: Barthel J. , Kunz W. , Lauermann G. , Neueder R. 
Published: March 2014

AbstractThe superimposition of Coulombian long range ion‐ion and non‐Coulombian short range interactions yields mean force potentials which are used to calculate the osmotic coefficients of various organic solvent systems via pair correlation functions. – The agreement with osmotic coefficients from vapor pressure experiments on 22 methanol, ethanol, 2‐propanol, and acetonitrile solutions of alkali metal and tetraalkylammonium salts shows the reliability of the chemical model of electrolyte solutions from infinite dilution to high concentrations.
Potentiostatic Current Oscillations of Cobalt Electrodes in Hydrochloric Acid/Chromic Acid Electrolytes
Authors: Hudson J. L. , Bell J. C. , Jaeger N. I. 
Published: March 2014

AbstractAutonomous potential oscillations of Co wires immersed in a hydrochloric acid/chromic acid electrolyte were thoroughly studied by Franck and Meunier [1]. The experimental system has now been reinvestigated under potentiostatic conditions using a rotating Co disk for easy and reproducible control of transport parameters. After reaching a plateau the cathodic current enters a region of negative resistance where the oscillations start with a hard bifurcation. The width of the oscillating regime depends on the experimental conditions and can be up to 100 mV. Within this range a transition between limit cycle oscillations and aperiodic oscillations can be observed. The onsetpotential for the oscillations depends on the logarithm of the HCl‐concentration. A mechanism for the oscillations will be proposed based upon pitting corrosion of a cathodic film formed during the cathodic reduction of chromic acid [2].
Forces and Torques Acting on Two Parallel Dielectric Cylinders in a Periodic Transverse Field. C. Limiting Case of Contacting Cylinders
Authors: Schlögl Reinhard W. 
Published: March 2014

AbstractThe interactions between two dielectric bodies in an outer field show rather strong deviations from the “long distance laws” if the surfaces of the two bodies approach contact. Image forces occur that require another type of mathematical procedure. Instead of a partial differential equation an integral equation has to be solved. In the special case of cylindrical bodies these solutions lead to Fourier transforms that can be integrated explicitly (in contrast to the case of two spheres where the integral equation is not yet solved).
Delayed Fluorescence of the Kautsky‐Müller Type from Liquid Solutions of Aromatic Compounds and Oxygen
Authors: Nickel Bernhard , Flor M. , Prieto Rodríguez 
Published: March 2014

AbstractTriplet‐singlet annihilation (TSA) T, + 1Δg → S1 + 3Σg− of the metastable triplet state (T1) of an aromatic compound and the metastable singlet state (1Δg) of molecular oxygen may lead to an observable delayed fluorescence (DF) S1 → S0 (DF of the Kautsky‐Müller type). A DF of this type has been observed with liquid solutions of phenanthrene and quinoxaline in perfluorohexane and of fluoranthene in 1,1,2‐trichloro‐1,2,2‐trifluoroethane in the presence of oxygen. The DF due to TSA can be kinetically distinguished from the DF due to triplet‐triplet annihilation (TTA). The results indicate a very long lifetime of 1Δg in perhalogenated alkanes. The DF from phenanthrene due to TTA can be assigned to the fluorescence from an excited dimer.
Investigation of Current Doubling Reactions at SiC/Aqueous Electrolyte Junction in Relation to the Band Energetics
Authors: Manivannan A. , Fujishima A. , Rao G. V. Subba 
Published: March 2014

AbstractThe current doubling behaviour of organic reagents especially alcohols by oxidation and persulfate by reduction was studied at n‐ and p‐SiC single crystals, respectively. In the case of n‐SiC no photocurrent increase was observed even under the acidic conditions with the addition of iso‐propyl alcohol whose alcohol radical potential lies most negative among the alcohols used. This implies that the conduction band position of n‐SiC is very negative. The radical intermediates formed during irradiation of n‐SiC suspension in various alcohols were analyzed by ESR spin trapping technique. On the other hand, current doubling behaviour was observed at p‐SiC during the reduction of persulfate ion by a hole injection into the valence band. This hole injection process was also confirmed by the EL (electroluminescence) studies. These results are discussed in terms of the interface energetics of SiC/aqueous electrolyte junction.
Influence of Hydrogen/Deuterium Isotope Substitution on the Critical Parameters of the System Polystyrene/Cyclohexane
Authors: Engels Th. , Belkoura L. , Woermann D. 
Published: March 2014

AbstractThe critical composition, the upper critical temperature and the critical amplitude ξ0 of local concentration fluctuations of the systems PSH/C6H12 and PSH/C6D12 are determined (PSH: poly(protostyrene); Mw = 3 · 105 g · mol−1; C6H12: cyclohexane; C6D12: cyclohexane‐d12). Both systems have the same critical composition (mole fraction of monomer unit of PSH: xc = 0.0573; volume fraction of PSH: ϕc(PSH/C6H12) = 0.0512; ϕc(PSH/C6D12) = 0.0500) and the same value of ξ0 within the accuracy of the measurements (PSH/C6H12: ξ0 = (6.83 ± 0.09) · 10−8 cm; PSH/C6D12: ξ0 = (6.86 ± 0.05) · 10−8 cm). Only the critical temperature of the system PSH/C6H12 (Tc(PSH/C6H12) = 26.338°C) is different from that of the system PSH/C6D12 (Tc(PSH/C6D12) = 30.582°C; Tc(PSH/C6D12) – Tc(PSH/C6H12) = 4.2 K). These findings suggest that the influence of a H/D substitution on the critical parameters follows the same pattern as that of binary critical mixtures of small molecules.
Microsomal protein per gram of liver (MPPGL) in paediatric biliary atresia patients
Authors: De Bock Lies , Boussery Koen , De Bruyne Ruth , Van Winckel Myriam , Stephenne Xavier , Sokal Etienne , Van Bocxlaer Jan 
Published: March 2014

ABSTRACTThe microsomal protein per gram of liver (MPPGL) is an important scaling factor in the in vitro–in vivo extrapolation of metabolic data obtained in liver microsomes. This study aimed to determine the MPPGL in four biliary atresia patients (0.6–1.6 years old) undergoing liver transplantation, as it is known that the MPPGL is affected by age and possibly by liver disease. Due to the presence of bilirubin in the homogenates and microsomes, the NADPH‐cytochrome reductase activity was used to determine the recovery factor, rather than methods using the dithionite difference spectrum. A mean value of 18.73 (± 2.82) mg/g (geometric mean ± SD, n = 4) was observed, which is lower than the expected MPPGL based on the age of the patients (26.60 ± 0.40 mg/g). This suggests a decreased amount of microsomal protein in the livers of biliary atresia patients. Moreover, no differences in MPPGL between different zones of the liver could be detected. Copyright © 2014 John Wiley & Sons, Ltd.
Candidate gene associations with mood disorder, cognitive vulnerability, and fronto‐limbic volumes
Authors: Frazier Thomas W. , Youngstrom Eric A. , Frankel Brian A. , Zunta‐Soares Giovana B. , Sanches Marsal , Escamilla Michael , Nielsen David A. , Soares Jair C. 
Published: March 2014

AbstractBackgroundFour of the most consistently replicated variants associated with mood disorder occur in genes important for synaptic function:ANK3(rs10994336),BDNF(rs6265),CACNA1C(rs1006737), andDGKH(rs1170191).AimsThe present study examined associations between these candidates, mood disorder diagnoses, cognition, and fronto‐limbic regions implicated in affect regulation.Methods and materialsParticipants included 128 individuals with bipolar disorder (33% male, Mean age = 38.5), 48 with major depressive disorder (29% male, Mean age = 40.4), and 149 healthy controls (35% male, Mean age = 36.5). Genotypes were determined by 5′‐fluorogenic exonuclease assays (TaqMan®). Fronto‐limbic volumes were obtained from high resolution brain images using Freesurfer. Chi‐square analyses, bivariate correlations, and mediational models examined relationships between genetic variants, mood diagnoses, cognitive measures, and brain volumes.ResultsCarriers of the minorBDNFandANK3alleles showed nonsignificant trends toward protective association in controls relative to mood disorder patients (P = 0.047).CACNA1Cminor allele carriers had larger bilateral caudate, insula, globus pallidus, frontal pole, and nucleus accumbens volumes (smallestr = 0.13,P = 0.043), and increasedIQ(r = 0.18,P < 0.001).CACNA1Cassociations with brain volumes andIQwere independent; larger fronto‐limbic volumes did not mediate increasedIQ. Other candidate variants were not significantly associated with diagnoses, cognition, or fronto‐limbic volumes.Discussion and conclusionsCACNA1Cmay be associated with biological systems altered in mood disorder. Increases in fronto‐limbic volumes and cognitive ability associated withCACNA1Cminor allele genotypes are congruent with findings in healthy samples and may be a marker for increased risk for neuropsychiatric phenotypes. Even larger multimodal studies are needed to quantify the magnitude and specificity of genetic‐imaging‐cognition‐symptom relationships.
An Azide‐Modified Nucleoside for Metabolic Labeling of DNA
Authors: Neef Anne B. , Luedtke Nathan W. 
Published: March 2014

AbstractMetabolic incorporation of azido nucleoside analogues into living cells can enable sensitive detection of DNA replication through copper(I)‐catalyzed azide–alkyne cycloaddition (CuAAC) and strain‐promoted azide–alkyne cycloaddition (SPAAC) “click” reactions. One major limitation to this approach is the poor chemical stability of nucleoside derivatives containing an aryl azide group. For example, 5‐azido‐2′‐deoxyuridine (AdU) exhibits a 4 h half‐life in water, and it gives little or no detectable labeling of cellular DNA. In contrast, the benzylic azide 5‐(azidomethyl)‐2′‐deoxyuridine (AmdU) is stable in solution at 37 °C, and it gives robust labeling of cellular DNA upon addition of fluorescent alkyne derivatives. In addition to providing the first examples of metabolic incorporation into and imaging of azide groups in cellular DNA, these results highlight the general importance of assessing azide group stability in bioorthogonal chemical reporter strategies.
Facile Synthesis of Au/g‐C3N4 Nanocomposites: An Inorganic/Organic Hybrid Plasmonic Photocatalyst with Enhanced Hydrogen Gas Evolution Under Visible‐Light Irradiation
Authors: Samanta Subhajyoti , Martha Satyabadi , Parida Kulamani 
Published: March 2014

AbstractNoble‐metal Au nanoparticles deposited on graphitic carbon nitride polymer (g‐C3N4) photocatalyst by a facile deposition–precipitation method exhibited high photocatalytic activity for hydrogen gas production under visible‐light irradiation. The Au/g‐C3N4 nanocomposite plasmonic photocatalysts were characterized by X‐ray diffraction spectroscopy, diffuse reflectance UV/Vis spectroscopy, FTIR spectroscopy, field‐emission scanning electron microscopy, high‐resolution transmission electron microscopy, selected‐area electron diffraction, X‐ray photoelectron spectroscopy, photoluminescence spectroscopy, and photoelectrochemical measurements. We studied the effect of Au deposition on the photocatalytic activity of g‐C3N4 by investigation of optical, electronic, and electrical properties. Enhanced photocatalytic activity of Au/g‐C3N4 naocomposite for hydrogen production was attributed to the synergic mechanism operating between the conduction band minimum of g‐C3N4 and the plasmonic band of Au nanoparticles including high optical absorption, uniform distribution, and nanoscale particle size of gold. The mechanism of te photocatalytic activity of the nanocomposite photocatalyst is discussed in detail. Deposition of Au nanoparticles on g‐C3N4 was optimized and it was found that 1 wt % Au‐loaded g‐C3N4 composite plasmonic photocatalyst generated a photocurrent density of 49 mA cm−2 and produced a hydrogen gas amount of 532 μmol under visible light, which were more than 3000 times higher and 23 times higher, respectively, than the values of neat g‐C3N4.
Conformational Analysis of a 20‐Membered Cyclic Peptide Disulfide from Conus virgo with a WPW Segment: Evidence for an Aromatic–Proline Sandwich
Authors: Sonti Rajesh , Rao K. N. Shashanka , Chidanand Sudarshan , Gowd Konkallu Hanumae , Raghothama Srinivasarao , Balaram Padmanabhan 
Published: March 2014

AbstractA novel peptide containing a single disulfide bond, CIWPWC (Vi804), has been isolated and characterised from the venom of the marine cone snail, Conus virgo. A precursor polypeptide sequence derived from complementary DNA, corresponding to the M‐superfamily conotoxins, has been identified. The identity of the synthetic and natural peptide sequence has been established. A detailed analysis of the conformation in solution is reported for Vi804 and a synthetic analogue, CIDWPWC (DW3‐Vi804), in order to establish the structure of the novel WPW motif, which occurs in the context of a 20‐membered macrocyclic disulfide. Vi804 exists exclusively in the cis W3P4 conformer in water and methanol, whereas DW3‐Vi804 occurs exclusively as the trans conformer. NMR spectra revealed a W3P4 type VI β turn in Vi804 and a type II′ β turn in the analogue peptide, DW3‐Vi804. The extremely high‐field chemical shifts of the proline ring protons, together with specific nuclear Overhauser effects, are used to establish a conformation in which the proline ring is sandwiched between the flanking Trp residues, which emphasises a stabilising role for the aromatic–proline interactions, mediated predominantly by dispersion forces.
Highly Efficient Direct Aerobic Oxidative Esterification of Cinnamyl Alcohol with Alkyl Alcohols Catalysed by Gold Nanoparticles Incarcerated in a Nanoporous Polymer Matrix: A Tool for Investigating the Role of the Polymer Host
Authors: Buonerba Antonio , Noschese Annarita , Grassi Alfonso 
Published: March 2014

AbstractThe selective aerobic oxidation of cinnamyl alcohol to cinnamaldehyde, as well as direct oxidative esterification of this alcohol with primary and secondary aliphatic alcohols, were achieved with high chemoselectivity by using gold nanoparticles supported in a nanoporous semicrystalline multi‐block copolymer matrix, which consisted of syndiotactic polystyrene‐co‐cis‐1,4‐polybutadiene. The cascade reaction that leads to the alkyl cinnamates occurs through two oxidation steps: the selective oxidation of cinnamyl alcohol to cinnamaldehyde, followed by oxidation of the hemiacetal that results from the base‐catalysed reaction of cinnamaldehyde with an aliphatic alcohol. The rate constants for the two steps were evaluated in the temperature range 10–45 °C. The cinnamyl alcohol oxidation is faster than the oxidative esterification of cinnamaldehyde with methanol, ethanol, 2‐propanol, 1‐butanol, 1‐hexanol or 1‐octanol. The rate constants of the latter reaction are pseudo‐zero order with respect to the aliphatic alcohol and decrease as the bulkiness of the alcohol is increased. The activation energy (Ea) for the two oxidation steps was calculated for esterification of cinnamyl alcohol with 1‐butanol (Ea=57.8±11.5 and 62.7±16.7 kJ mol−1 for the first and second step, respectively). The oxidative esterification of cinnamyl alcohol with 2‐phenylethanol follows pseudo‐first‐order kinetics with respect to 2‐phenylethanol and is faster than observed for other alcohols because of fast diffusion of the aromatic alcohol in the crystalline phase of the support. The kinetic investigation allowed us to assess the role of the polymer support in the determination of both high activity and selectivity in the title reaction.
Noble Metals Can Have Different Effects on Photocatalysis Over Metal–Organic Frameworks (MOFs): A Case Study on M/NH2‐MIL‐125(Ti) (M=Pt and Au)
Authors: Sun Dengrong , Liu Wenjun , Fu Yanghe , Fang Zhenxing , Sun Fangxiang , Fu Xianzhi , Zhang Yongfan , Li Zhaohui 
Published: March 2014

AbstractM‐doped NH2‐MIL‐125(Ti) (M=Pt and Au) were prepared by using the wetness impregnation method followed by a treatment with H2 flow. The resultant samples were characterized by powder X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), X‐ray absorption fine structure (XAFS) analyses, N2‐sorption BET surface area, and UV/Vis diffuse reflectance spectroscopy (DRS). The photocatalytic reaction carried out in saturated CO2 with triethanolamine (TEOA) as sacrificial agent under visible‐light irradiations showed that the noble metal‐doping on NH2‐MIL‐125(Ti) promoted the photocatalytic hydrogen evolution. Unlike that over pure NH2‐MIL‐125(Ti), in which only formate was produced, both hydrogen and formate were formed over Pt‐ and Au‐loaded NH2‐MIL‐125(Ti). However, Pt and Au have different effects on the photocatalytic performance for formate production. Compared with pure NH2‐MIL‐125(Ti), Pt/NH2‐MIL‐125(Ti) showed an enhanced activity for photocatalytic formate formation, whereas Au has a negative effect on this reaction. To elucidate the origin of the different photocatalytic performance, electron spin resonance (ESR) analyses and density functional theory (DFT) calculations were carried out over M/NH2‐MIL‐125(Ti).The photocatalytic mechanisms over M/NH2‐MIL‐125(Ti) (M=Pt and Au) were proposed. For the first time, the hydrogen spillover from the noble metal Pt to the framework of NH2‐MIL‐125(Ti) and its promoting effect on the photocatalytic CO2 reduction is revealed. The elucidation of the mechanism on the photocatalysis over M/NH2‐MIL‐125(Ti) can provide some guidance in the development of new photocatalysts based on MOF materials. This study also demonstrates the potential of using noble metal‐doped MOFs in photocatalytic reactions involving hydrogen as a reactant, like hydrogenation reactions.