bluuebunny/crossref_metadata_2025 huggingface dataset:
The tides of Mercury and possible implications for its interior structure
Authors: Padovan Sebastiano , Margot Jean‐Luc , Hauck Steven A. , Moore William B. , Solomon Sean C.
Published: March 2014

The combination of the radio tracking of the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft and Earth‐based radar measurements of the planet's spin state gives three fundamental quantities for the determination of the interior structure of Mercury: mean density ρ, moment of inertia C, and moment of inertia of the outer solid shell Cm. This work focuses on the additional information that can be gained by a determination of the change in gravitational potential due to planetary tides, as parameterized by the tidal potential Love number k2. We investigate the tidal response for sets of interior models that are compatible with the available constraints (ρ, C, and Cm). We show that the tidal response correlates with the size of the liquid core and the mean density of material below the outer solid shell and that it is affected by the rheology of the outer solid shell of the planet, which depends on its temperature and mineralogy. For a mantle grain size of 1 cm, we calculate that the tidal k2 of Mercury is in the range 0.45 to 0.52. Some of the current models for the interior structure of Mercury are compatible with the existence of a solid FeS layer at the top of the core. Such a layer, if present, would increase the tidal response of the planet.
On modeling the paleohydrologic response of closed‐basin lakes to fluctuations in climate: Methods, applications, and implications
Authors: Liu Ganming , Schwartz Franklin W.
Published: March 2014

Climate reconstructions using tree rings and lake sediments have contributed significantly to the understanding of Holocene climates. Approaches focused specifically on reconstructing the temporal water‐level response of lakes, however, are much less developed. This paper describes a statistical correlation approach based on time series with Palmer Drought Severity Index (PDSI) values derived from instrumental records or tree rings as a basis for reconstructing stage hydrographs for closed‐basin lakes. We use a distributed lag correlation model to calculate a variable, ωt that represents the water level of a lake at any time t as a result of integrated climatic forcing from preceding years. The method was validated using both synthetic and measured lake‐stage data and the study found that a lake's “memory” of climate fades as time passes, following an exponential‐decay function at rates determined by the correlation time lag. Calculated trends in ωt for Moon Lake, Rice Lake, and Lake Mina from A.D. 1401 to 1860 compared well with the established chronologies (salinity, moisture, and Mg/Ca ratios) reconstructed from sediments. This method provides an independent approach for developing high‐resolution information on lake behaviors in preinstrumental times and has been able to identify problems of climate signal deterioration in sediment‐based climate reconstructions in lakes with a long time lag.
Salinity effects on cracking morphology and dynamics in 3‐D desiccating clays
Authors: DeCarlo Keita F. , Shokri Nima
Published: March 2014

Saline conditions induce not only chemical but physical changes in swelling clays, and have a significant influence on the crack dynamics and morphology of desiccating clays. In this study, we used X‐ray microtomography to experimentally investigate the effects of sodium chloride on the morphology and dynamics of desiccation cracks in three‐dimensional mixtures of sand‐bentonite slurry under varying rheological conditions. Rectangular glass containers were packed with slurries of different salt concentrations, with the top boundary exposed to air for evaporation. The growth and propagation of the cracking network that subsequently formed was visualized in 3‐D at multiple intervals. The characterization of cracking and branching behavior shows a high extent of localized surficial crack networks at low salinity, with a transition to less extensive but more centralized crack networks with increased salinity. The observed behavior was described in the context of the physicochemical properties of the montmorillonite clay, where shifts from an “entangled” (large platelet spacing, small pore structure) to a “stacked” (small platelet spacing, open pore structure) network influence fluid distribution and thus extent of cracking and branching behavior. This is further corroborated by vertical profiles of water distribution, which shows localized desiccation fronts that shift to uniform desaturation with increasing salt concentration. Our results provide new insights regarding the formation, dynamics, and patterns of desiccation cracks formed during evaporation from 3‐D saline clay structures, which will be useful in hydrological applications including water management, land surface evaporation, and subsurface contaminant transport.
Theory of transient streaming potentials in coupled unconfined aquifer‐unsaturated zone flow to a well
Authors: Malama Bwalya
Published: March 2014

A semianalytical solution is presented for transient streaming potentials associated with flow to a pumping well in an unconfined aquifer, taking into account the effect of flow in the unsaturated zone above the water table. Flow in the unsaturated zone is modeled with a linearized form of Richards' equation using an exponential model for soil moisture retention and unsaturated hydraulic conductivity. Archie's law is invoked for unsaturated electrical conductivity. The unsaturated electrokinetic coupling coefficient is modeled with a decaying exponential, where the maximum value is at and below the water table. The coupled flow and electrokinetic problem is solved using Laplace and Hankel transforms. The results of the model predicted behavior are presented and compared to that observed in laboratory simulations of pumping tests. The early time polarity reversal predicted the model is observable in the experiments. Other nonmonotonic streaming potential behaviors predicted by the model are also evident in experimental measurements. The model is used to estimate hydraulic parameters from SP data and these compare well to those obtained from drawdown data. For example, a hydraulic conductivity of 3.6 × 10−4 m/s is obtained from SP data compared to 3.4 × 10−4 m/s from drawdown data.
Pulsed Laser Ablation Based Synthesis of PbS‐Quantum Dots‐Decorated One‐Dimensional Nanostructures and Their Direct Integration into Highly Efficient Nanohybrid Heterojunction‐Based Solar Cells
Authors: Ka I. , Gonfa B. , Le Borgne V. , Ma D. , El Khakani M. A.
Published: March 2014

The pulsed laser deposition (PLD) technique is used for the direct fabrication of nanohybrid heterojunctions (NH‐HJs) solar cells exhibiting high PCE and excellent stability in air without any encapsulation and/or resorting to any surface treatment, ligand engineering and/or post‐synthesis processing. The NH‐HJs are achieved through the PLD‐based decoration of hydrothermally‐grown one‐dimensional TiO2 nanorods (TiO2‐NRs) by PbS quantum dots (PbS‐QDs). By optimizing both the amount of PbS‐QDs (via the number of laser ablation pulses) and the length of the TiO2‐NRs, it is possible to achieve optimal NH‐HJs based PV devices with high power conversion efficiency (PCE) of 4.85%. This high PCE is found to occur for an optimal length of the NRs (≈290 nm) which coincides with the average penetration depth of PbS‐QDs into the porous TiO2‐NRs matrix, leading thereby to the formation of the largest extent of NH‐HJs. Most importantly, the PCE of these novel devices is found to be fairly stable for several months under ambient air. The addition of single‐wall carbon nanotubes (SWCNTs) onto the TiO2‐NRs prior to their decoration by PbS‐QDs is shown to further enhance their PCE to a value as high as 5.3%, because of additional light absorption and improved charge collection ensured by SWCNTs.
Atomistic Modeling of Corrosion Resistance: A First Principles Study of O2 Reduction on the Al(111) Surface Covered with a Thin Hydroxylated Alumina Film
Authors: Costa Dominique , Ribeiro Thomas , Mercuri Francesco , Pacchioni Gianfranco , Marcus Philippe
Published: March 2014

In the early stage of corrosion of Al or Al alloys (i.e., during the initiation of localized corrosion), an oxide film is generally present on the surface. This work investigates the possibility for a cathodic reaction to occur on these oxide films. We discuss realistic models of supported oxide films on Al(111) in order to disentangle the factors determining the reactivity towards O2. Three components of the complex film formed on Al(111) can be identified: an ultrathin under‐stoichiometric AlxOy interface layer, an intermediate Al2O3 phase with γ‐alumina structure, and an hydroxylated AlOOH surface termination with boehmite structure. The electron transfer to O2 molecules depends on the workfunction, Φe, of the metal/oxide interface and on the thickness of the inner Al2O3 phase. The electron transfer takes place both from the metal‐oxide interface and the oxide surface to the adsorbed O2 molecule. Very important is the role of the hydroxyl groups at the surface: they eliminate the Al surface states and stabilize the surface; they allow the reduced O2
− species to capture protons and transform into hydrogen peroxide in a non‐activated process. H2O2 is further reduced to two water molecules, in a series of two‐electron mechanisms. These reactions take place only when the internal alumina phase is ultrathin (here 0.2 nm). As soon as an Al2O3 inner layer develops (film thickness of about 1 nm), the film becomes unreactive and passivates the Al(111) surface. The results help to shed light on the complex reactions responsible for metal corrosion.
Reference intervals of complete blood count constituents are highly correlated to waist circumference: Should obese patients have their own “normal values?”
Authors: Vuong Jennifer , Qiu Yuelin , La Myanh , Clarke Gwen , Swinkels Dorine W. , Cembrowski George
Published: March 2014

Body mass index (BMI), the prevalent indicator of obesity, is not easily grasped by patients nor physicians. Waist circumference (WC) is correlated to obesity, is better understood and has a stronger relationship to the metabolic syndrome. We compiled WC, complete blood count (CBC) parameters as well as other pertinent data of 6766 25–55‐year‐old US volunteers sampled in the US National Health and Nutrition Examination Survey, in the years 2005–2010. To determine reference intervals of typical US patients visiting their clinician, we used minimal exclusion criteria. We compiled hemoglobin, red blood cell count, hematocrit, mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration, mean cell hemoglobin (MCH), red cell distribution width (RDW), platelet count, mean platelet volume, and counts of white blood cells (WBC), neutrophils, lymphocytes, monocytes, eosinophils, and basophils. In addition, we also compiled serum C reactive protein and serum iron. The three major US races were studied and reference interval diagrams were constructed for each CBC parameter plotted against WC. WBC count, RDW, lymphocyte, neutrophil, and red blood cell count increase with WC. Conversely, serum iron and MCH and MCV decrease. These relationships may be related to insulin resistance and chronic activation of the immune system and the resulting low‐grade inflammatory state. WC is a strong predictor for many CBC parameters, suggesting that WC should be taken into account when evaluating blood count results. Clinicians who take care of obese patients should be aware of altered hematology and investigate and treat accordingly. Am. J. Hematol. 89:671–677, 2014. © 2014 Wiley Periodicals, Inc.
A novel mutation in the SLC40A1 gene associated with reduced iron export in vitro
Authors: Moreno‐Carralero María‐Isabel , Muñoz‐Muñoz Juan‐Antonio , Cuadrado‐Grande Nuria , López‐Rodríguez Rafaela , José Hernández‐Alfaro María , del‐Castillo‐Rueda Alejandro , Enríquez‐de‐Salamanca Rafael , Méndez Manuel , Morán‐Jiménez María‐Josefa
Published: March 2014

Ferroportin disease is an inherited disorder of iron metabolism and is caused by mutations in the ferroportin gene (SLC40A1). We present a patient with hyperferritinemia, iron overload in the liver with reticuloendothelial distribution and also in the spleen, and under treatment with erythropheresis. A molecular study of the genes involved in iron metabolism (HFE, HJV, HAMP, TFR2, SLC40A1) was undertaken. In vitro functional studies of the novel mutation found in the SLC40A1 gene was performed. The patient was heterozygous for a novel mutation, c.386T>C (p.L129P) in the SLC40A1 gene; some of his relatives were also heterozygous for this mutation. In vitro functional studies of the L129P mutation on ferroportin showed it impairs its capacity to export iron from cells but does not alter its sensitivity to hepcidin. These findings and the iron overload phenotype of the patient suggest that the novel mutation c.386T>C (p.L129P) in the SLC40A1 gene has incomplete penetrance and causes the classical form of ferroportin disease. Am. J. Hematol. 89:689–694, 2014. © 2014 Wiley Periodicals, Inc.
MMP13 mutations are the cause of recessive metaphyseal dysplasia, Spahr type
Authors: Bonafé Luisa , Liang Jinlong , Gorna Maria W. , Zhang Qingyan , Ha‐Vinh Russia , Campos‐Xavier Ana Belinda , Unger Sheila , Beckmann Jacques S. , Le Béchec Antony , Stevenson Brian , Giedion Andres , Liu Xuanzhu , Superti‐Furga Giulio , Wang Wei , Spahr André , Superti‐Furga Andrea
Published: March 2014

Metaphyseal dysplasia, Spahr type (MDST; OMIM 250400) was described in 1961 based on the observation of four children in one family who had rickets‐like metaphyseal changes but normal blood chemistry and moderate short stature. Its molecular basis and nosologic status remained unknown. We followed up on those individuals and diagnosed the disorder in an additional member of the family. We used exome sequencing to ascertain the underlying mutation and explored its consequences on three‐dimensional models of the affected protein. The MDST phenotype is associated with moderate short stature and knee pain in adults, while extra‐skeletal complications are not observed. The sequencing showed that MDST segregated with a c.619T>G single nucleotide transversion in MMP13. The predicted non‐conservative amino acid substitution, p.Trp207Gly, disrupts a crucial hydrogen bond in the calcium‐binding region of the catalytic domain of the matrix metalloproteinase, MMP13. The MDST phenotype is associated with recessive MMP13 mutations, confirming the importance of this metalloproteinase in the metaphyseal growth plate. Dominant MMP13 mutations have been associated with metaphyseal anadysplasia (OMIM 602111), while a single child homozygous for a MMP13 mutation had been previously diagnosed as “recessive metaphyseal anadysplasia,” that we conclude is the same nosologic entity as MDST. Molecular confirmation of MDST allows distinction of it from dominant conditions (e.g., metaphyseal dysplasia, Schmid type; OMIM # 156500) and from more severe multi‐system conditions (such as cartilage‐hair hypoplasia; OMIM # 250250) and to give precise recurrence risks and prognosis. © 2014 Wiley Periodicals, Inc.
Molecularly imprinted electrochemical sensor for the determination of ampicillin based on a gold nanoparticle and multiwalled carbon nanotube‐coated pt electrode
Authors: Wei Shoulian , Liu Yong , Hua Tao , Liu Ling , Wang Hongwu
Published: March 2014

A novel molecularly imprinted electrochemical sensor was developed for the sensitive and selective determination of ampicillin (AMP). The sensor was prepared on a platinum electrode modified with multiwalled carbon nanotubes (MWCNTs), gold nanoparticles (AuNPs), and a thin film of molecularly imprinted polymers (MIPs). MWCNTs and AuNPs were introduced to enhance the sensor's electronic transmission and sensitivity. The molecularly imprinted polymer (MIP) was synthesized using AMP as the template molecule, methacrylic acid as functional monomer, and ethylene glycol maleic rosinate acrylate (EGMRA) as cross‐linker. The performance of the proposed imprinted sensor was investigated using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). The results showed that the imprinted film displayed a fast and sensitive response to AMP. Under optimal conditions, response peak current had a linear relationship with the concentration of AMP in the range of 1.0 × 10−8 mol/L to 5.0 × 10−6 mol/L and a detection limit of 1.0 × 10−9 mol/L (S/N = 3). This imprinted sensor was used to detect AMP in food samples with recoveries of 91.4–105%. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40613.
A comparative study of ethylene and propylene polymerization over titanium–magnesium catalysts of different composition
Authors: Nikolaeva Marina , Matsko Mikhail , Mikenas Tatiana , Zakharov Vladimir
Published: March 2014

New data on the molecular weight characteristics of polypropylene (PP) and polyethylene (PE) were obtained from the polymerization over supported titanium–magnesium catalysts differing in their compositions (presence and absence of internal and external donors). Internal and external donors were found to affect the molecular weight of polymers in a different manner for ethylene and propylene polymerization. The introduction of the internal donor increases the molecular weight of PP and does not affect the molecular weight of PE. The effect of external donor introduced to catalytic system on the polymer molecular weight depends on catalyst composition: for a catalyst without internal donor, the introduction of the external donor increases the molecular weight of PP and does not affect that of PE. In the case of catalyst with the internal donor, the introduction of the external donor increases the molecular weight of PP and substantially decreases that of PE. The data on polymerization degree of the polymers produced under conditions when chain transfer with hydrogen was the dominant reaction were used to calculate the
values for ethylene polymerization over the catalysts of different composition. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40658.
Influence of fillers and bonding agents on the viscoelasticity of highly filled elastomers
Authors: Azoug Aurélie , Nevière Robert , Pradeilles‐Duval Rachel‐Marie , Constantinescu Andrei
Published: March 2014

Highly filled elastomers such as solid propellants exhibit a complex nonlinear viscoelastic behavior. This work aimed at determining the influence of binder–filler and filler–filler interactions on the microstructure and the viscoelastic properties of the propellant using a design of experiments method. The influences of the filler fraction and of the filler–binder bonding agents (FBBA) were measured by swelling experiments and prestrained dynamic mechanical analyses. The results showed that FBBA react on the filler surface and concentrate the curing agents in the vicinity of the fillers. The nonlinearity of the viscoelastic behavior originated from filler–filler interactions that created high stress zones between fillers and therefore constrained the movements of the macromolecules of the binder. Filler–binder interactions induced by the FBBA increased the filler effective volume as well as the heterogeneous stress distribution in the microstructure. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2014,131, 40664.
Differential Thermal Analysis under High Pressure I: Investigation of the Polymerisation of Liquid Sulfur
Authors: Kuballa M. , Schneider G. M.
Published: March 2014

A DTA apparatus constructed for pressures up to 4000 bar and temperatures to 500°C is described.

It was applied to the qualitative and calorimetric investigation of the monomer‐polymer equilibrium in liquid sulfur (commonly called Sλ‐Sμ transition). A resulting polymerisation line determined by the connection of the floor temperatures at different pressures shows only a slight negative pressure dependence; it starts at 159°C at normal pressure and intercepts the melting curve at approx. 155°C and 1300 bar the slope of the P(T)‐curve becoming increasingly steeper.

The increase of polymer formation in liquid sulfur at the Sλ‐Sμ transition can be deduced quantitatively from the calorimetric measurements.
Die Katalyse der Isotopenaustauschreaktion HTO + H2= HT + H2O an der intermetallischen Verbindung NiGa
Authors: Best K. J. , Grabke H. J.
Published: March 2014

Der Austausch von Tritium in strömenden H2O  H2‐Gemischen nach HTO + H2= HT + H2O wurde an Ni, Fe und Legierungen aus dem Homogenitätsbereich der intermetallischen Phase NiGa bei Temperaturen oberhalb 500°C untersucht. Im Homogenitätsbereich des NiGa zwischen 49 und 56 a/o Ga ändern sich die Fermienergie, die Konzentrationen an Punktfehlstellen und die Enthalpie der Sauerstoffadsorption merklich; der Zusammenhang dieser physikalischen und chemischen Eigenschaften mit den katalytischen Eigenschaften der Verbindung wird diskutiert.

Die Abhängigkeit der Reaktionsgeschwindigkeit von der SauerstoffaktivitätpH2O/PH2=a0ergibt Aussagen über das Adsorptionsgleichgewicht H2O = H2+ O(ad) an den untersuchten Metallen. Die Enthalpie und Enthalpie der Sauerstoffadsorption wurden bestimmt. Am Eisen wurden bei hoher Sauerstoffaktivität reversible Änderungen der Oberflächenstruktur (Reliefbildung) und der Kinetik der Oberflächen‐reaktion beobachtet, ähnliche, aber irreversible Änderungen treten beim NiGa auf.
Kinetics of a Simple Charge Transfer Reaction at a Slurry Electrode
Authors: Hurwitz H. D. , Srinivasan S. , Litt M.
Published: March 2014

A theoretical treatment is presented for an electrochemical cell in which a suspension of catalytically active particles and fuel stream through the anodic compartment. The overall rate of discharge of the particles at the collector electrode is supposedly controlled either by electrochemical oxydation of chemisorbed species on the particle surface (case of hydrogen reaction) or by charge transfer through a resistance at the contact‐making spot between the collector electrode and the catalyst particle. Special emphasis is given to hydrodynamic determination of collision frequencies with the collector electrode of suspended particles, as a function of their dimension and of the state of turbulency, in order to derive current efficiencies of slurry electrodes under various experimental conditions.
Molekulargewichtsverteilung von Formaldehyd in wäßrigen Lösungen
Authors: Koberstein E. , Müller K.‐P. , Nonnenmacher G.
Published: March 2014

Zur Entwicklung eines vereinfachten Strukturmodells für die Formaldehydpolymerisation in wäßriger Lösung werden Ergebnisse von 1H‐NMR‐Untersuchungen herangezogen. Es wird gezeigt, daß ein Modell mit nur einer einzigen Gleichgewichtskonstanten die Molekulargewichtsverteilung in wäßrigen Formaldehydlösungen quantitativ beschreibt.
NMR‐spektroskopische Untersuchungen über die Eigenassoziation von Karbonsäuren in inerten Lösungsmitteln I. Iterative Berechnung thermodynamischer Größen für Essigsäure
Authors: Jentschura U. , Lippert E.
Published: March 2014

Sorgfältig hergestellte Proben erlaubten die Messung der chemischen Verschiebung δ des Essigsäure‐COOH‐PMR‐Signals gegen TMS bis herab zu Essigsäurekonzentrationen c = 2,7 · 10−4 mol/l in Cyclohexan bzw. 6,3 · 10−4 mol/l in Tetrachlorkohlenstoff. Bis herauf zu c ≈︁ 0,04 bzw. 0,06 mol/l hängt ∂ im wesentlichen nur vom Monomer‐Dimer‐Gleichgewicht ab, während bei den Werten c = 0,4 bzw. 0,7 mol/l, bei denen ∂ = f(c) ein Minimum besitzt, auch größere Assoziate (Multimere) eine Rolle spielen. Die Frequenzen vm für das Monomere (mit dvm/dT ≈︁ 0) und vD für das Dimere (mit dvD/dT < 0) werden iterativ bestimmt. Die ermittelten Assoziationskonstanten (T = 300°K) liegen in der Größenordnung 103 < Kc < 104l/mol. Aus deren Temperaturabhängigkeit im Bereich von 300 bis 360°K wird die Assoziationsenthalpie zu — ΔH = (12460 ± 160) bzw. (11350 ± 150) cal/mol bestimmt.

Dieser Wert stimmt innerhalb der Fehlergrenzen mit dem IR‐spektroskopischer Arbeiten überein. Widersprüchliche Ergebnisse früherer PMR‐spektroskopischer Untersuchungen werden diskutiert.
Matrix‐Isolation Applied to High‐Temperature and Interstellar Molecules: A Review
Authors: Weltner William
Published: March 2014

The contributions of optical and electron‐spin‐resonance (ESR) spectroscopy at 4 K to the determination of the electronic, vibrational, and magnetic properties of high‐temperature and interstellar molecules are briefly reviewed. The present status of the ground state properties of the transition‐metal oxide, nitride, carbide, and hydride molecules are considered. Other molecules produced by the vaporization of beryllium, carbon, silicon, silicon carbide, boron, and boron carbide are also discussed. Numerous metastable molecules for which spectral data are lacking remain to be detected in interstellar space. It is probable that the role of matrix‐isolation, as exemplified by the identification of the interstellar ethynyl and cyanoethynyl radicals via ESR studies at 4 K, will become increasingly important because of the difficulties in observing many reactive molecules in the gas phase.
Photoemission Studies on Rare Gas Matrices
Authors: Koch E. E. , Nürnberger R. , Schwentner N.
Published: March 2014

Photoelectron energy distribution measurements with synchrotron radiation are very useful for the determination of energy levels and the band structure of pure and doped solid rare gas matrices and for the investigation of energy transfer processes. The band formation in Xe–Ar alloys with varying concentration and energy transfer processes in Xe doped Ar and Ne matrices are described and discussed.
Vibrational Relaxation in Matrices
Authors: Dubost Henri
Published: March 2014

This paper is a review of the work in the field of vibrational relaxation in matrix isolated molecules. After an historical survey time resolved experiments are described and the essential results are presented. The various relaxation processes are then discussed. A classification of molecules according their mode of relaxation is proposed.
Adsorptions‐ und Grenzflächenverhalten von Gangliosiden an der Phasengrenze Quecksilber/Elektrolyt
Authors: WÖrner M. , Greiner G. , Rau H. , Rahmann H. , Probst W.
Published: March 2014

The behavior of three sialoglycolipids of different polarity (the gangliosides GM1, GD1a, GT1b) have been investigated at the Hg/electrolyte interface by means of ac polarography. In solution the gangliosides exist as micelles. We have determined the dependence of the differential capacity of the electrical double layer on the potential difference across this layer and on pH, temperature and addition of bivalent cations (Ca2+, Mg+). The structure of the double layer varies at different electrode potentials. At anodic potentials specific adsorption of ganglioside clusters with the charged head groups towards the electrode is observed. At about +0.2 V (NHE) a rearrangement, reversion of the molecules and strong adsorption of their nonpolar hydrocarbon chains between +0.1 V and −0.7 V is observed. At the stationary electrode (HMDE) at a potential of about −0.8 V condensation of the clusters to a monolayer is inferred which is destroyed at about −1.2 V, probably with desorption of the gangliosides from the electrode. Ca2+ ions induce increased stability of the monolayer at the electrode, a specific Ca2+‐effect is verified by comparison with Mg2+. The relevance of these findings for biological membranes is discussed.
Local Defect Equilibria: The Conceptual Difficulties in Treating Solid State Reaction Kinetics
Authors: Pfeiffer T. , Schmalzried H. , Ueshima Y.
Published: March 2014

For an AO — BO interdiffusion process a formal analysis is given. The conceptual difficulties in using either structural elements, building units or components in the framework of irreversible thermodynamics are discussed. The matrix of transport coefficients of a n‐component system is evaluated and is transformed into a matrix of diffusivities. The interdiffusion problem has been solved numerically, starting with a set of two coupled diffusion equations. Point defect relaxation during interdiffusion has been taken into account through a quasi‐homogeneous point defect relaxation term. The calculated supersaturation and undersaturation of point defects result in concentration profiles which cannot be normalized with √t. Experiments with the diffusion couple FeO — MnO demonstrate the theoretically predicted behavior and the influence of the cation vacancy relaxation at the sample surface on the concentration profiles.
Influence of Pressure on the Transition Phenomenon in Diluted Solutions of Poly(diacetylenes)
Authors: Hennecke Manfred , Düll Ines , Fuhrmann Jürgen
Published: March 2014

Hydrostatic pressure in the range from 1 to 3400 bar induces the transition phenomenon in diluted solutions of polydiacetylenes. With respect to the influence of pressure on the absorption bands, the transition was studied by UV spectroscopy. The transition is shown to depend strongly on the hydrogen bonds between the sidegroups. In the case of P‐DDD which is free of H‐bonds, the temperature and pressure effect on the transition is first‐order‐like in that temperature range where no precipitation occurs. Transient processes, except those involving precipitated particles, occur below the experimental time scale of minutes. In P‐4BCMU, a polydiacetylene with H‐bonds between the sidegroups, the pressure‐induced isothermal transient phenomena are slowed down, and exhibit a nonexponential time law. The transition shows a hysteresis in temperature in such a way that the heating branch of the hysteresis loop is remarkably shifted by pressure to higher temperatures whilst the cooling branch remains nearly unshifted. Hydrostatic pressure is shown to give additional information concerning the molecular origin of the transition phenomenon.
Combustion and Diffusion Flames at High Pressures to 2000 bar
Authors: Schilling W. , Franck E. U.
Published: March 2014

The combustion of methane with oxygen in supercritical homogeneous aqueous fluids has been investigated and stationary diffusion flames generated to pressures of 2000 bar. A reaction autoclave with sapphire windows contains high pressure homogeneous mixtures of water and methane to 500°C. A typical mixture composition is 70 to 30 mole percent of H2O and CH4. A quasi‐circular fluid flow permits the steady injection of oxygen through a 0.5 mm nozzle at rates of 1 — 10 mm3 s−1 at constant pressures. — Above 400°C spontaneous ignition of flames occurred. The flames were observed and recorded with microscope and video camera. Emission spectra in the UV‐region were obtained and samples could be taken for analysis. Below about 400°C flame‐less oxidation is detected. The stationary diffusion flames are cone‐shaped and typically about 3 mm high. Flame examples for pressures between 300 and 2000 bar are shown. Preliminary temperatures derived from OH‐spectra are close to 3200 K. — Water can be replaced by argon.
Rheo‐Optical Fourier‐Transform Infrared Spectroscopy of Polymers 14. Segmental Orientation and Strain‐Induced Crystallization of a Poly(Ether Urethaneurea) Elastomer
Authors: Siesler H. W.
Published: March 2014

The versatility and potential of rheo‐optical Fourier‐Transform infrared (FTIR) spectroscopy is demonstrated with reference to the characterization of segmental orientation in a poly(ether urethaneurea) elastomer. The rheo‐optical data show that the soft and hard segments of the polymer deform by different orientation mechanisms. Thus, the soft segments exhibit an almost perfect reversibility of orientation and desorientation in loading and unloading cycles, whereas the deformation of the hard segments is dominated by a significant reorganization of their morphology. Furthermore, rheo‐optical FTIR spectroscopy provided an extremely sensitive tool for detecting the onset, progress and decay of strain‐induced crystallization of the soft segments during the mechanical treatment of the elastomer.
Accurate Measurement of the Melting Line of Methanol and Ethanol at Pressures up to 270 MPa
Authors: Sun T. F. , Schouten J. A. , Trappeniers N. J. , Biswas S. N.
Published: March 2014

The P‐T melting curves of methanol and ethanol have been measured precisely at pressures up to 270 MPa and 200 MPa respectively, using the ultrasonic method developed previously. The accuracy of the experimental melting temperatures is about 0.1 K and of the melting pressures about 0.8 MPa for both liquids. The accuracy of the experimental results, fitted to the Simon‐Glatzel equation, is sufficient for the precise calculation of thermodynamic properties along the melting line.
Thermodynamic Study of the Al + Ga + In System: Comparison Between Experimental Measurements and Values Calculated with the HOCH‐ARPSHOFEN Model
Authors: Girard Claude , Bros Jean Pierre , Hoch Michael
Published: March 2014

The excess functions of formation of the Al + Ga + In liquid system have been calculated from the corresponding binary ones by using the Hoch‐Arpshofen interaction model. These results have been compared to the experimental values deduced from calorimetric and potentiometric measurements. Moreover enthalpies of formation were also compared to those calculated by using two polynomial — Kohler and Colinet — relations. The theoretical critical temperatures of the liquid miscibility gap calculated from the Gibbs free energy values confirm our previous observation: the third metal (Ga) lowers the critical solution temperature; so the critical solution surface has no ternary maximum of tempertur.
The Scaling of Nonequilibrium Fluctuations in Gaseous Thermal Explosions
Authors: Fernández Ariel , Rabitz Herschel
Published: March 2014

Closed gaseous systems are considered in contact with a heat bath, undergoing a thermal explosion in the rarified gas regime (0.02–0.06 atm.) where the effect of turbulent fluctuations in temperature and acoustic fields on the reaction rate is negligible. This situation is chosen to elucidate the stochastic nature of the ignition processes. An ensemble of combustion experiments is treated where in some replicas, the explosion is accelerated while in others, it is retarded. The influence of spatially localized temperature inhomogeneities on the stochastic ignition process is examined. The induction period is calculated making use of the time‐dependence of the probability distribution of temperatures over the ensemble. This induction period is identified with the Kramers mean passage time corresponding to a critical fluctuation‐induced diffusion across a barrier in an unsymmetric bistable potential. The potential is determined from the competition between the heat production given by the exothermic reaction and the heat removal process. One of the potential wells corresponds to the stationary combustion regime and the other well, to the explosive regime. The critical fluctuations are confined to a virtual volume corresponding to a hot spot whose size is determined from generalized fluctuation‐dissipation theory. As an example, the experimentally measured induction periods for the explosive decomposition of ethyl azide are found to be in very good agreement with our predictions. This treatment successfully explains the discrepancies which arise for the size‐dependence of the induction period and the Frank‐Kamenetsky constant when comparing results from classical Semenov theory and experimental evidence of premature explosions.
The Formation of Isocyanates on Noble Metals and Supported Noble Metal Catalysts
Authors: Schüth F. , Wicke E.
Published: March 2014

The formation of support‐NCO and noble metal‐NCO groups on oxide supported noble metal catalysts and high area evaporated metal films during the NO/CO reaction was studied by FTIR spectroscopy. With SiO2 and A12O3 as supports the results reported in the literature were essentially reproduced. With TiO2 and ZrO2 absorption bands in the region between 2000 and 2100 cm−1 were detected, which had not been described before. On evaporated metals NCO‐groups could be detected in situ. They are located at 2185 cm−1 for Pd and at 2170 cm−1 for Pt. Based on kinetic measurements the spillover of NCO‐groups from the noble metal to the support is proposed as a mechanism for support‐NCO formation. For this spillover a connection between support and noble metal is necessary, which is formed during hydrogen treatment at elevated temperatures. This connecting species could be a noble metal/support intermetallic phase, as Pd3Ti resp. Pt3T
Thermal Decomposition of Cyanogen Bromide Measured in BrCN/O2/Ar Reaction System by Atomic Resonance Absorption
Authors: Gulati S. K. , Roth P.
Published: March 2014

The thermal decomposition of cyanogen bromide has been measured in the temperature range 1640—2260 K at pressures of about 3.8–4.5 bar using the shock tube technique. Mixtures of BrCN/O2 highly diluted in argon were heated by reflected shock waves and O atom concentrations were monitored in the post shock reaction zone by using Atomic Resonance Absorption Spectroscopy (ARAS). Because of the fast secondary reactions of the dissociation product CN, the rate coefficient for the dissociation of cyanogen bromide could be experimentally determined from the measured O atom concentrations. They are closely fit by the Arrhenius expression:

The present rate coefficient data is in good agreement with the result recommended by Baulch et al. [6]
Cation Membrane Transport: Evidence for Local Validity of Nernst‐Planck Equations
Authors: Ratkje Signe Kjelstrup , Holt Torleif , Skrede Magne Geir
Published: March 2014

Local transport coefficients have been experimentally determined for transport of H+, Na+, H2O and current, and for transport of K+, Sr2+, H2O and current in a cation exchange membrane. Adjacent electrolytes contained 0.03 N solution mixtures of HCl and NaCl, or 0.03 N or 0.01 N solution mixtures of KCl and SrCl2. The fluxes and forces used in the presentation are based on a choice of neutral and independent components of the system. — The concentration dependence of the membrane conductivity and the electric mobility of ions has been described by a model which relates the reduction of one cation mobility to the equivalent fraction of the other cation. The mobility ratio varies between 4 and 15 for uH+/uNa+ and 3 and 6 for uk+/uSr2+. The transference numbers for the monovalent salt system can be predicted within experimental uncertainty limits from this model. Local diffusion coefficients are derived and compared to electric mobilities. The result is that the Nernst‐Planck equation using equal electric and diffusional mobility is valid for all concentrations within ± 10% on the average for both systems. Water transport will modify the Nernst‐Planck flux equations when gradients in chemical potential of water becomes about 10−5 times the gradients in chemical potential of salts. Calculations predict a negligible contribution to the chemical potential gradient of salts from pressure variations in the membrane during interdiffusion. — In total these results make possible a continuous description of membrane transport processes.
Raman Spectrometric Study of the Composition of Sulfur Vapor at Temperatures up to 700°C
Authors: Lenain Pascal , Picquenard Eric , Corset Jacques , Jensen Detlef , Steudel Ralf
Published: March 2014

Sulfur vapor has been investigated by Raman spectroscopy in a wide temperature and pressure range (300 to 900°C, 0.05 to 0.5 MPa for overheated vapor and 0.007 to 1.65 MPa for saturated vapor). At least eight different species have been observed through their characteristic Raman lines. Well separated Raman lines have been selected for the observation of the change in vapor composition with temperature: symmetrical bending modes for the cyclic species S8, S7, and S6 and stretching modes for the chain‐like species S3 and S2. There are indications for the presence of two conformational isomers of S4, and in addition a new species has been discovered by its resonance Raman line at 635 cm−1 which is tentatively assigned to chain‐like molecules Sn (n > 4) of helical conformation. Several relationships between the thermodynamic properties of the vapor and the Raman measurements are proposed, e.g., the determination of the temperature at which the molar fraction xi is maximum for the overheated vapor at constant pressure; estimation of the xi/x8 ratios using solution measurements of the Raman cross section for the molecules S8, S7, S6. A careful comparison of these results with the values deduced from Rau's model results in good agreement for the behavior of most of the species apart from S7 which is underestimated in Rau's model. S7 is the dominating species in saturated sulfur vapor above 600 K until S2 takes over at ca. 1000 K.
Evidence for Spinodal Decomposition in a Single Component Fluid
Authors: Klein H. , Schmitz G. , Woermann D.
Published: March 2014

Experimental conditions are reported under which scattering patterns characteristic for spinodal decomposition have been observed in a single component fluid, sulfur hexa‐fluoride (SF6). Analysis of the data shows that the development of the ring shaped patterns is consistent with the requirements of spinodal decomposition within the accuracy of the measurements.
Effect of Pressure on the Hydrogen‐Bond Formation III. Phenol‐Tertiary Amines and ‐Acetates in n‐Hexane
Authors: Sawamura S. , Taniguchi Y. , Suzuki K.
Published: March 2014

The effects of pressure on the hydrogen‐bond (H‐bond) formations between phenol as a proton donor and tertiary amines (Et3N, n‐Pr3N, and n‐Bu3N) or acetates (MeOAc, EtOAc, n‐PrOAc, and n‐BuOAc) as proton acceptors in n‐hexane were studied by means of the UV absorption spectroscopy up to 640 MPa at 25°C. The reaction volumes (ΔV) for H‐bond formations at 0.1 MPa were −10.7, −7.7, −8.0, −3.5, −4.2, −1.1, and −2.5 cm3 mol−1, respectively. These observed ΔV values were related to the theoretical ΔVest calculated by the extended Hamann's method. The method is applicable to the determination of the ΔV for the other molecular complex formations.
Liquid‐Liquid Extraction of Copper by Terdodecylthioglycolic Acid. Structures for the Extracted Species
Authors: Beneitez P.
Published: March 2014

The extraction of Cu(II) from nitrate medium by dodecylthioglycolic acid and the influence of buffered medium on that extraction have been studied at 293 K. Distribution of the metal ion in a wide range of pH and carboxylic acid concentration has been measured. Experimental data, treated by a graphical method have been interpreted by assuming the presence in the organic phase of the species CuDTG2 · HDTG2 and CuDTGAc · HDTG2. Characterization and structure of the solid compounds isolated from the extract have been discussed on the basis of elemental analysis, thermal gravimetric analysis, IR spectra and measurement of magnetic susceptibility.
Zur unimolekularen β‐Spaltung großer n‐Alkylradikale
Authors: Olzmann M. , Scherzer K.
Published: March 2014

Thermal fall‐off curves for ethylen split‐off from higher alkyl radicals are calculated on the basis of RRKM theory and an empirical representation of weak collision effects. It is shown that rate constants under conditions of industrial pyrolysis do not reach their high pressure limit.
Measurements of Dielectric Permittivity Near the Consolute Critical Point of Methanol‐Cyclohexane Mixture
Authors: Orzechowski Kazimierz
Published: March 2014

The dielectric permittivity as a function of temperature and frequency for a near critical methanol + cyclohexane mixture was investigated. A low frequency dispersion (fr = 150 kHz) was found which is usually interpreted in terms of the Maxwell‐Wagner polarization. The “static” dielectric constant was measured at 2000 kHz, and a decrease of the |dϵ/dT| value close to Tc was observed. The critical properties of the ϵ · v product (where ϵ is the static dielectric constant, and v is the specific volume) was described in terms of the Sengers et al. model. The results yield the critical exponent 1 – α = 0.89, rather than 2β = 0.65. Neglecting the specific volume anomaly leads to a slight decrease of the obtained exponent value.
Defect Structures in Membranes: Routes for the Permeation of Small Molecules
Authors: Lawaczeck R.
Published: March 2014

Transient defect structures in thermodynamic equilibrium with the membrane lattice are considered to be major pathways for the passive permeation of small and neutral (with the possible exception of protons) molecules. Results on the water permeation and on the transfer of protons across erythrocyte membranes are discussed. The inhibition/stimulation of transport rates is interpreted in terms of specific or global actions of the inhibitory/stimulatory molecules on lipid/protein and protein/protein assemblies.
Interaction of Ganglioside and Glycoprotein Carbohydrates with Membrane Surfaces
Authors: Ollmann M. , Tampé R. , Winter A. , Wohlfart P. , Galla H.‐J.
Published: March 2014

Electron spin resonance techniques were employed to investigate the interaction of sialic acid bearing carbohydrates covalently bound to gangliosides or glycophorin with membrane surfaces. In phosphatidylcholine membranes it was found that gangliosides induce a rigidification. This hydrophobic effect is partially compensated by a hydrophilic interaction with the membrane surface. In phosphatidylethanolamine membranes ganglioside GD1a is the only one that reduces the lipid phase transition temperature. We assume a special oligosaccharide conformation, that strongly disturbs the hydrogen bond network of the PE host membrane. The results are further supported by experiments with reconstituted glycophorin containing membranes. In a phosphatidylcholine matrix we observed the formation of an immobilized lipid domain that surrounds the protein. Phosphatidylethanolamines within a phosphatidylcholine membrane are excluded from such a domain. This is also interpreted by the formation of hydrogen bonds between sialic acid groups of the protein and the amino functions of the lipid headgroups.
Structural Fluctuations of Polypeptides in Lipid Membranes
Authors: Vogel Horst , Nilsson Lennart , Rigler Rudolf , Voges Klaus‐Peter , Jung Günther
Published: March 2014

Time‐resolved fluorescence anisotropy (FA) measurements are reported for five helical, bilayer spanning heneicosapeptides, each containing one Trp at sequence position 1, 6, 11, 16, and 21, respectively. The FA decay reflects two molecular processes in all cases, local internal fluctuations of the Trp side chain with a relaxation time of 200–500 ps and motions of the whole polypeptide molecule with a relaxation time of 9–10 ns. Concomitant molecular dynamics calculations indicate a correlation between the fast FA decay and conformational fluctuations within the helix.
Light Stimulated Ion Fluxes Across the Plasma Membrane of Photoreceptors
Authors: Rüppel H. , Cieslik J.
Published: March 2014

In vertebrate photoreceptors the main step of signal transduction process occurs at the plasma membrane of the outer segments. In darkness Na+‐ and Ca++‐ions are passing this membrane. There is an influx of Na+ but no net flux of Ca++‐ions. After a light pulse the Na+‐current is transiently reduced and the outer Ca++‐concentration increased. By diffusion the Ca++‐ions are rapidly distributed