bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrotransport in Molten KTl Alloys
Authors: Matsuda Takumichi , Nakamura Yoshio , Kitajima Masahiro , Shimoji Mitsuo 
Published: September 2012

AbstractThe electrotransport in molten K—Tl alloys has been measured as a function of composition. It is found that Tl atoms migrate to the anode in the K‐rich and intermediate (1:1) regions, while K atoms migrate to the anode in the Tl‐rich region. In the K‐rich region the difference in the electron‐ion scattering cross sections appears to be the dominant factor in the determination of the relative direction of migration. The charge transfer effect has been suggested around the KTl composition. In the Tl‐rich region the solvation of K atoms by Tl has also been suggested by the analogy with the K—Hg system.
Self‐Diffusion in Benzene‐Toluene and Benzene‐Cyclohexane Solutions
Authors: Reimschüssel W. , Hawlicka E. 
Published: September 2012

AbstractThe self‐diffusion in benzene‐toluene and benzene‐cyclohexane solutions have been measured at different temperatures. The capillary‐cell method was employed. The activation parameters of self‐diffusion for the systems are presented. The data have been used to test the validity of various diffusion equations proposed in the literature. The hypothesis that the self‐diffusion was realized by movement of aggregates of molecules is suggested.
Photochemical Reactions of Acridan Studied by CIDNP
Authors: Schwarz W. , Hesse P. , Dörr F. 
Published: September 2012

AbstractThe method of chemically induced dynamic nuclear polarization (CIDNP) is applied to investigate the photochemical reactions of acridan and some substituted acridans in alcoholic solutions at room temperature. It is shown that the CIDNP effect is due to the radical pair N‐radical ‐ H. which is formed from a triplet precursor. In the presence of CCl4 or CHCl3, the pair N‐radical, ·CCl3 (or ·CHCl2) is formed by direct reaction from the singlet state.
Analytical Solution of Fick's Second Law when the Diffusion Coefficient is a Linear Function of Concentration
Authors: Lin Ping‐Luen , Pelton A. D. 
Published: September 2012

AbstractAn analytical method of explicitly solving the diffusion equation is presented for the case in which the diffusion coefficient is a linear function of concentration, D(c) = D0(b0 + b1(c/c0)). For b0 > 0 and b1 > 0, the solution has been worked out explicitly so that one can obtain conveniently an analytical equation for the diffusion profile from the diffusion coefficient, or vice versa, for moving as well as stationary boundaries. The solution is applied to calculate the kinetic parameters for spinel formation via the solid state reaction NiO + Cr2O3 ‐ NiCr2O4 for a variety of initial and boundary conditions.
Chlornitrit, ein metastabiles Zwischenprodukt der Reaktion von Dichlormonoxid mit Nitrosylchlorid
Authors: Janowski B. , Knauth H.‐D. , Martin H. 
Published: September 2012

AbstractDas vor dieser Untersuchung unbekannte Chlornitrit CIONO bildet sich in heterogener Reaktion aus gasförmigem CINO und Cl2O bei Temperaturen um 223 K und bei Partialdrücken zwischen 4 und 40 Torr gemäß CINO + Cl2OCIONO + Cl2als metastabiles Zwischenprodukt, das unter diesen Bedingungen zwar langsam (t1/2 ≈ 4 bis 20 Stunden) aber vollständig zu Nitrylchlorid weiterreagiert: CIONOCINO2.Die Isomerisierungsreaktionen liefern nach 1. Ordnung ab, waren aber ebenfalls nicht frei von heterogenen Anteilen. Die Reaktionsabläufe wurden IR‐photometrisch verfolgt in temperierbaren Küvetten aus Duranglas mit aufgeschmolzenen Si‐Fenstern.—Vier von den fünf in der Molekülebene liegenden, zum Teil sehr starken (vs) A'‐Fundamentalschwingungsbanden wurden aus dem IR‐Spektrum von gasförmigem CIO14NO (CIO15NO) erhalten; v/cm−1 = 1715 (1684) (vs), 858 (850), 644 (638), 406 (401) (vs). Sie passen gut zusammen mit den Banden von CIO14NO in Cl2‐Matrix: v/cm−1 = 1718, 1702 (Dublett); 850; 645, 641 (Dublett); 390. Die fünfte, sehr intensitätsarme A'‐Bande wurde in der Cl2‐Matrix bei 256 cm−1 gefunden und für gasförmiges CIONO aus Kombinationsbanden abgeschätzt: v/cm−1 ≈ 260 bis 280. Eine C‐Typ‐Bande, an der die Torsionsschwingung beteiligt sein sollte und für die es mehrere Zuordnungsmöglichkeiten gibt, wurde im Gasspektrum bei v/cm−1 = 344 (338) entdeckt. Über Modellrechnungen, bei denen von Strukturparametern und Kraftkonstanten analoger Verbindungen ausgegangen wurde, ließ sich nicht entscheiden, ob CIONO in der cis‐ oder trans‐Modifikation vorliegt.—Eine festkörperspezifische Modifikation wurde durch Tempern von CIONO, das in der Gasphase erzeugt, mit überschüssigem Cl2 versetzt und auf einem mit flüssigem N2 gekühlten (CsJ)‐Fenster ausgefroren wurde, erhalten: v/cm−1 = 1834; 790; 671, 653, 631 (Triplett); 363; 309, 302 (Dublett). Ohne vorherige Bildung der in der Gasphase beständigen Modifikation entstand die Festkörpermodifikation durch langsames gleichzeitiges Aufdampfen von CINO und Cl2O (Überschußpartner und Matrixsubstanz) auf ein mit flüssigem N2 gekühltes (NaCl)‐Fenster: v/cm−1 = 1835, 1817 (Dublett); 787; 669, 650, 628 (Triplett). Die teilweise sehr scharfen Banden weisen auf definierte Molekülassoziate hin.
The Stirred Flow Reactor: Base Analog Incorporation in DNA Replication and Transcription
Authors: Bhat Ramachandra , Kuhn Wilfried , Schneider Friedemann W. 
Published: September 2012

AbstractWe compare base analog incorporation in two template processes that are carried out in a stirred flow reactor at the steady state. In calf thymus DNA transcription with RNA polymerase we use inosine as a base analog to guanine and determine its percent incorporation P(I) into RNA. P(I) is found to be independent of average residence time in the stirred fow reactor and dependent on the initial concentration of ITP relative to GTP in both open and closed systems. In poly[d(A‐T)] replication with DNA polymerase I we use 2‐aminopurine as a base analog for adenine. By contrast, the percent incorporation of 2‐aminopurine is strongly dependent on average residence time in the stirred flow reactor besides showing a dependency on initial concentration of 2‐aminopurine (n2 h2 dATP). Thus the base analog incorporation probability may be affected by the residence time in replication but not in transcription. This difference is due to the effect of kinetic nonlinearities in poly[d(A‐T)] replication as carried out under present concentration conditions.
Statistical Mechanical Calculations of Molecular Pair Correlation Functions and Scattering Intensities
Authors: Bertagnolli H. 
Published: September 2012

AbstractFor the case of special molecular models representing the acetonitrile molecule the expansion coefficients of the molecular pair distribation function are calculated by use of perturbation theory. These results are used to get theoretical access to scattering intensities in the frame of several approximations. The first model describes the molecule by three hard spheres and uses a hard sphere liquid as a reference. In the second case the calculations are based on an anisotropic Lennard‐Jones potential by application of a model of overlapping ellipsoids and by use of a Lennard‐Jones liquid as a reference system. In the third model dipolar attractive forces are taken into account with an anisotropic hard‐sphere liquid as a reference. Finally all the calculations with different intermolecular potentials are compared with neutron scattering experiments.
Hydration Properties of Oxygen Containing Linear Heterohydrocarbons as Studied by Dielectric Relaxation Measurements
Authors: Kaatze Udo 
Published: September 2012

AbstractComplex permittivities of aqueous solutions of ethylene‐glycols, HO‐(CH2‐CH2‐O)n‐H (n = 1, 2, 3, 4, 4.1, 8.7, or 13.2, and of ethylene‐glycol dimethylethers, H3C‐O‐(CH2‐CH2‐O)n,‐CH3 (n = 1, 2, or 3), have been measured at 11 up to 13 frequencies in the range 2 to 40 GHz by an interferometric transmission method. A sum of relaxation functions has been fitted to the observed data to yield the hydration number and reorientation time of the hydration water. The values of these parameters are discussed and compared with those for poly (ethylene oxide) of different degree of polymerization and those for other series of organic solutes in order to get insight into the effect of various molecular parameters on the microdynamics of the surrounding water.
Transport of Isotopes in Systems with Reversibly Reacting Species. I: General Equations
Authors: Schönert H. 
Published: September 2012

AbstractGeneralized phenomenological equations of transport are derived for isothermal systems in which each neutral or ionic constituent or species exists as a mixture of several isotopes, except for the solvent. For this reason the following hypotheses is used: the entropy production is independent of isotopic composition. Relationships between generalized conductivity coefficients and the tracer diffusion coefficients are derived. The limiting behaviour of these coefficients is discussed.
Tracer Diffusion Coefficients in Aqueous Electrolyte Solutions of Various Structure Forming and Breaking Ions
Authors: Reiners G. , Lorenz W. J. , Hertz H. G. 
Published: September 2012

AbstractThe tracer‐diffusion coefficients of Fe2+, Fe3+, [Fe(CN)6]4‐, [Fe(CN)6]3‐ and Ag+‐ions have been determined electrochemically on a rotating gold disc electrode in various supporting electrolytes. It is shown that the diffusion process is specifically affected by the surroundings of the supporting electrolyte counter‐ion, that is, by the structure forming or structure breaking property. A semiquantitative interpretation of the data obtained yields response factors of ≤1.0 in good agreement with a model previously reported. Temperature dependences of the diffusion processes yielding activation energies confirm the statements made.
Bestimmung des Assoziationsgrades binärer Legierungsschmelzen durch Analyse der Liquiduslinie in der Umgebung des Schmelzpunktes einer intermetallischen Verbindung
Authors: Sommer F. , Eschenweck D. , Predel B. 
Published: September 2012

AbstractEs werden Beziehungen entwickelt, die eine Berechnung des Assoziatanteils aus dem Verlauf der Liquiduslinie in der Umgebung einer intermetallischen Verbindung ermöglichen. Für die Legierungsschmelzen des Systems Magnesium‐Zinn wurde für eine A2B‐Assoziationstendenz ein maximaler Assoziatanteil von 82% erhalten.
NMR‐Untersuchungen an Lösungen mit Nitroxidradikalkomplexen. II. Hyperfeinkopplungskonstanten, Linienbreiten und Relaxation von Komplexen mit n‐Propanol, Isopropanol und tert.‐Butanol
Authors: Dally E. , Müller‐Warmuth W. 
Published: September 2012

AbstractDie durch die Wasserstoffbrücke zu einem freien Nitroxidradikal verursachten NMR‐Kontaktverschiebungen und Linienverbreiterungen wurden für n‐Propanol, Isopropanol und tert.‐Butanol in Lösungen von Tetrachlorkohlenstoff untersucht. Um Gleichgewichtskonstanten und Bildungsenthalpien der Komplexe zu bestimmen, wurden die Temperatur sowie die Alkoholkonzentration variiert. Es wurden Hyperfeinkopplungskonstanten zwischen ‐0,9 und ‐1,5 MHz gefunden, deren Größe von stereospezifischen Faktoren abhängt und die leicht temperaturabhängig sind. Für n‐Propanol und Isopropanol wurde das Zusammenfallen der Multiplettstruktur des OH‐Protons durch Verändern von Temperatur und Radikalkonzentration untersucht. Aus Linienbreiten‐ und Relaxationsmessungen bei unterschiedlichen Frequenzen und Temperaturen konnten dipolare und skalare Anteile von T1−1 und T2−1 getrennt und die Zeitkonstanten der Molekülbewegung sowie die Lebensdauer der Komplexe berechnet werden.
Löslichkeit von Wasserstoff in Aminen
Authors: Brunner E. 
Published: September 2012

AbstractDie Löslichkeit von Wasserstoff in Aminoethan, 1,2‐Diaminoethan, 1‐Aminopropan, 2‐Aminopropan, 1,3‐Diaminopropan, Pyrrolidin. Piperidin, 1‐Methylpyrrolidin, 1‐Dimethylaminopropylamin‐3, 1‐Methylpiperidin, Triethylamin, 1,6‐Diaminohexan, Bis‐(3‐aminopropyl)‐amin, Dimethylaminocyclohexan, Di‐n‐butylamin, N,N'‐Bis‐(3‐aminopropyl)‐ethylendiamin und Tri‐n‐butylamin wurde bei 25, 50 und 100°C und im allgemeinen bis 100 bar Gesamtdruck gemessen. Die Genauigkeit der Löslichkeitsmessungen ist besser als 2%.
Basic Polypeptides as Histone Models: Interaction of Block Copolymers of [LysnAlam] with Calf Thymus DNA
Authors: Klump H. , Kricheldorf H.‐R. 
Published: September 2012

AbstractBlock copolymers were synthesized by blockwise copolymerization of Z‐L‐Lys‐NCA and D,L‐Ala‐NCA initiated by tert.‐butylamines. The lysine block consisted always of 20 residues, the length of the alanine block (Pn) was either 10 or 20 residues. Complexes of the copolymers with calf thymus DNA were prepared by mixing the dilute solutions of the polyelectrolytes at different ratios (cation/anion) rapidly. Melting curves of the complexes were recorded at 260 nm. The shift of the melting temperature Tm is discussed as a function of the input ratio of cations and the results are compared to the results obtained with CT‐DNA and polylysine.
4‐Pentadecyl‐7‐hydroxycoumarin as a Probe for the Structure of the Lipid‐Water‐Interface Comparative Studies with Lipid Monolayers, Black Lipid Membranes and Lipid Microvesicles
Authors: Teissié J. , Tocanne J. F. , Pohl W. G. 
Published: September 2012

AbstractThe apparent pK of a lipoid pH‐Indicator was measured in lipid monolayers, “black” lipid membranes and lipid microvesicles. The results are discussed with respect to the Gouy‐Chapman theory, the chemical structure and packing density of the different lipids used in the study, and the possible application of lipoid pH‐indicators in biological studies.
Dynamic Molecular Organization in Vesicles and Membranes
Authors: Sackmann E. 
Published: September 2012

AbstractThe physico chemical properties of lipid layers and membranes which are of special interest in connection with processes in organized molecular assemblies are summarized. In particular the basic physical principles governing structure formation in lipid/protein/water systems are discussed. As a first step towards structure formation the self association of lipids in water is discussed. It is then shown that 2‐dimensional lipid mixtures possess an intrinsic tendency towards lateral structure (domain) formation which originates in differences in symmetry of the possible polymorphic states of lipid layers. Evidence is provided that the lateral structure formation is greately enforced by incorporation of macromolecules into lipid layers, while in membranes containing charged lipids, domain formation may also be triggered by electrostatic binding of water soluble proteins. ‐The origins of the spontaneous structure formation in lipid/protein systems are (1) cooperative lipid protein interaction which is caused by lipid‐mediated elastic long range forces, (2) the capacity of proteins to select specific lipids in lipid alloys either by electrostatic forces or by a steric‐elastic effect. Finally, it is shown that (domain) structure formation is a very fast process, which, in the presence of charged lipids, may be accompanied by pronounced hysteresis effects. The close analogies between the physical properties of lipid mixtures and metal alloy are discussed.
Current Noise Generated in Lipid Bilayer Membranes by Carrier‐Mediated Ion Transport
Authors: Kolb H.‐A. , Läuger P. 
Published: September 2012

AbstractValinomycin‐mediated ion transport generates in lipid bilayer membranes a characteristic type of current noise spectrum completely different from noise spectra in the presence of pore‐forming substances like gramicidin, alamethicin or monazomycin.At equilibrium the current noise of the carrier system yields to a spectral intensity “white” (frequency independent) both at the low and high frequency end of the spectrum. Between the low and high frequency range of the spectrum the spectral intensity increases with frequency. The frequency range of transition is correlated to the characteristic relaxation time constants of this transport system. The experimental behaviour of the spectral intensity can be theoretically described on the basis of the Nyquist theorem applied for the carrier transport model.
Spannungsabhängige Beiträge zur Kapazität einer Lipidmembran
Authors: Carius W. 
Published: September 2012

AbstractDie Spannungs‐ und Frequenzabhängigkeit der Kapazitäts‐änderung δC wurde unter verschiedenen experimentellen Bedingungen an ebenen Lipidmembranen gemessen. Dabei zeigten sich vielfach signifikante Abweichungen von der üblichen quadratischen Spannungsabhängigkeit δC = αU2. Der Beitrag von lateralen Schwingungen an der Grenzlinie Bilayer/Lipidlösung (z. B. am Torus) kann durch seine Frequenzabhängigkeit f−0.5 charakterisiert werden. Zur Erklärung der experimentellen. Befunde werden theoretische Modelle zur Diskussion gestellt.
On Domain Structure and Local Curvature in Lipid Bilayers
Authors: Krbecek R. , Gebhardt C. , Gruler H. 
Published: September 2012

AbstractThe lateral lipid organization and phase transition behaviour in giant bilayer vesicles of pure lipid systems and lipid mixtures were investigated. Both systems exhibit domain‐like structures at the surface of the vesicles. Since the domain structure often is accompanied by a local variation in curvature, freeze fracture electron microscopy was considered to be a suitable investigation technique.Pure lipid systems show periodically rippled or spiral domain patterns, respectively. The rippled structure is obtained between the pre‐ and maintransition. It is explained by the concept of spinodal decomposition of metal alloys and the orientational elastic model of membranes. The periodicity of the ripples is determined by the spontaneous curvature of the decoupled mono‐ layers of a bilayer. Analysing the defect structure of the ripples one gets additional information on the molecular orientation. ‐ The spiral pattern is obtained in the case of coupled biaxial mono‐ layers below the pretransition. Binary and ternary lipid mixtures of smectic phases of different symmetry undergo lateral phase separation leading to rippled and spherically shaped domain organizations. The thermotropic phase separation behaviour of the various mixtures of phosphatidyl cholin, phosphatidic acid and cholesterol is discussed.The oblique platinum shadowing leads to a different platinum layer thickness at different membrane locations. Densitometric analysis of the electron micrographs yields refined information upon the finestructure of the surface profile of the membranes.
The Stability of Phospholipid Dispersions
Authors: Rydhag Lisbeth , Rosenquist Kenneth 
Published: September 2012

AbstractLipid vesicles were made by sonication of well defined phospholipids above the chain‐melting temperature. Fractionation was obtained by ultracentrifugation. The vesicle size was determined with different methods, for example by different light scattering methods and by determination of the sedimentation coefficients in an analytical ultracentrifuge. The influence of size and charge were studied with respect to the stability of the lipid vesicles.
Thermotropic Phase Transition and Ultrasonic Absorption in Lecithin Bilayer Vesicle Preparations
Authors: Funck Th. , Eggers F. 
Published: September 2012

AbstractTemperature dependent ultrasonic absorption spectra (frequency range 0.3‐150 MHz) of homogeneous lecithin bilayer vesicle preparations in the range of their liquid/liquid‐crystalline phase transition provide information on equilibrium shifts for various states of the lipid system. Furthermore the frequency dependence of the absorption reveals time constants of elementary processes which cause the ultrasonic absorption. From our measurement data the following conclusions can be drawn:

The thermotropic phase transition in our lipid system is not a one‐step reaction but incorporates various processes.
Predominant changes of the ultrasonic absorption with temperature, correlated with cooperative processes at the lipid/water interface, occur well below the temperature of the “calcrimetric” main effect.
Relaxation times of these processes are between 10 and 200 ns.
The observed ultrasonic absorption appears to be larger than expected values from equilibrium (“static”) data (e. g. dilatometry and calorimetry); consequently in this case the ultrasonic absorption indicates processes with compensating effects, which can only be resolved by “dynamic” methods on the time scale.
These kinetic observations are compared with results from calorimetry, density‐ and viscosity‐measurements on the same lipid preparations. A model mechanism for the thermotropic phase transition in lecithin bilayer vesicles is suggested.
Steric Interaction of Fluid Membranes
Authors: Helfrich W. 
Published: September 2012

AbstractOptical observation of giant lecithin vesicles does not show any indication of cohesion between thin lecithin membranes consisting of a small number of bilayers (W. Harbich, H. J. Deuling, and W. Helfrich, J. Phys. (Paris) 38, 727 (1977). It may be concluded that cohesion, if it exists at all, must be weaker by orders ofmagnitude than the calculated strength of van der Waals interaction (B. W. Ninham and V. A. Parsegian, J. Chem. Phys. 53, 3398 (1970).However, there should also be a repulsive force acting between fluid membranes, caused by the mutual steric hindrance of out‐of‐plane fluctuations. We show that the two interactions have the same range and may compete in strength. The experimental situation concerning multilayer systems and red blood cells is discussed from this point of view.
Procedure to Form Bilayer‐Gel Membranes
Authors: Lüschow Ullrich , Schulz‐Harder Jürgen 
Published: September 2012

AbstractWe developed a new procedure that induces multifunctional reagents to crosslink at an interface between a black bilayer and the adjacent water phase. This procedure yields “bilayer‐gel” membranes, i. e. membranes consisting of a bilayer and a polymer layer. The bilayer‐gel membrane may partially be considered to be a new membrane system, because the formation of the polymer layer changes some bilayer properties.We studied bilayer‐gel membranes composed of a bilayer of oxidized cholesterol and of a polymer layer of poly‐1‐lysine crosslinked by glutardialdehyde. Compared to unmodified bilayers, this membrane system has an electrical conductance of the same magnitude, the same electrical capacity, and similar shapes of current‐voltage dependences. Yet, this system is asymmetrical and differs in the increased stability from an unmodified bilayer. The ion selectivity of bilayer‐gel membranes depends upon the chain length of the polylysine the polymer layer is formed with. Trilysine and tetralysine yield a membrane selectivity for cations. Polylysine with MW > 6000 D yields an anionic selectivity. Some properties of bilayer‐gel membranes, mainly their resistance, are sensitive to a change of the pH and to the ionic strength of the adjacent solutions.The special kinetics of the formation of the polymer layer and the instability of the bilayer require some general conditions which must be observed for forming bilayer‐gel membranes.