bluuebunny/crossref_metadata_2025_split huggingface dataset:
Capabilities of chemical simulation methods in the elucidation of structure and dynamics of solutions
Authors: Hofer Thomas S. , Pribil Andreas B. , Randolf Bernhard R. 
Published: June 2008

AbstractAs a result of recent methodological developments in connection with enhanced computational capacity, theoretical methods have become increasingly valuable and reliable tools for the investigation of solutions. Simulation techniques utilizing a quantum mechanical (QM) approach for the treatment of the chemically most relevant region so-called hybrid quantum mechanical/molecular mechanical (QM/MM) simulations have reached a level of accuracy that often equals or may even surpass experimental methods. The latter is true in particular whenever ultrafast (i.e., picosecond) dynamics prevail, such as in labile hydrates or structure-breaking systems. The recent development of an improved QM/MM framework, the quantum mechanical charge field (QMCF) ansatz, enables a broad spectrum of solute systems to be elucidated. As this novel methodology does not require any solute solvent potential functions, the applicability of the QMCF method is straightforward and universal. This advantage is bought, however, at the price of a substantial increase of the QM subregion, and an attendant increase in computational periods to levels of months, and even a year, despite parallelizing high-performance computing (HPC) clusters. Molecular dynamics (MD) simulations of chemical systems showing increasing complexity have been performed, and demonstrate the superiority of the QMCF ansatz over conventional QM/MM schemes. The systems studied include Pd2+, Pt2+, and Hg22+, as well as composite anions such as PO43-and ClO4-.
Coarse-graining in suspensions of charged nanoparticles
Authors: Dahirel Vincent , Jardat Marie , Dufrêche Jean-François , Lucas Ivan , Durand-Vidal Serge , Turq Pierre 
Published: June 2008

Abstract
A coarse-grain description of nanocolloidal suspensions in the presence of an added salt is presented here. It enables us to simulate trajectories of the nanoparticles from effective functions that depend on average densities of salt ions. In practice, the ion-averaged effective potential is used as input of a Brownian dynamics (BD) simulation. This potential may be derived by various methods, ranging from purely analytical to fully numerical ones. For the description of dynamical properties, this simulation also requires an effective diffusion coefficient that must be calculated or experimentally determined, and that accounts for the effects of microions on the mobility of the nanoparticles. The different versions of our coarse-graining procedure are applied to the case of a maghemite suspension, for which an explicit description of all ions would be very time-consuming.
What can be learnt from dielectric relaxation spectroscopy about ion solvation and association?
Authors: Buchner Richard 
Published: June 2008

Abstract
Ion solvation and ion association are key features of ion-solvent interactions, and their balance largely determines structure, thermodynamics, and dynamics of electrolyte solutions. Despite being studied for many years with various techniques, these effects are still intriguing because too often results obtained with different methods-each having its individual merits and limitations-cannot be connected properly due to lacking information. In this contribution, we would like to bring dielectric relaxation spectroscopy (DRS) as a further tool for solution studies to the attention of the audience. The principles of DRS and the required instrumentation are briefly introduced. The major focus will be on the kind of results obtained with this technique regarding ion solvation and association and how this information compares with results obtained from other techniques.
Polyelectrolyte hydration: Theory and experiment
Authors: Vlachy Vojko 
Published: June 2008

AbstractA short review of recent theoretical and experimental advances in studies of polyelectrolyte solutions is presented. The focus is on ion-specific effects as revealed in measurements of osmotic pressure and enthalpy of dilution. We review the experimental results for two different polyelectrolyte systems: (i) salts of polyanetholesulfonic acid, and (ii) aliphatic ionenes (polycations) in aqueous solution with various counterions. A theoretical approach based on the extension of Wertheim's integral equation theory [J. Stat. Phys.35, 19 (1984)] is used to analyze the experimental data. Preliminary results, based on the all-atom simulation of model 3,3 ionene oligomers, are discussed in the light of polyelectrolyte hydration.
Ionic interactions in aqueous mixtures of hydrophilic and -phobic ions
Authors: Kumar Anil 
Published: June 2008

AbstractIons of both hydrophilic and -phobic nature play a pivotal role in biological systems and during synthesis of many organic molecules. However, the interaction of a hydrophilic ion with a hydrophobic one is not a simple physical process and is useful in understanding the rate enhancement in organic transformations and thermal stability of DNA and RNA. During the talk, an attempt was made to present some of the experimental work on aqueous mixtures of these ions carried out at National Chemical Laboratory, Pune, and give a theoretical interpretation of the binary, ternary, and quaternary interactions operating in these systems. The contribution of these interaction terms to the excess free energy of mixing, ΔmGE, will be analyzed.
Isoequilibrium relationships and cooperative effects in spin-state transitions in solution
Authors: Hassan Nader , Koudriavtsev Andrei B. , Linert Wolfgang 
Published: June 2008

Abstract
Thermal induced spin transitions between low- and high-spin states of Fe(II) complexes are commonly observed in the solid state. Cooperative effects, such as abrupt and two-step spin crossover, are typical for these objects and arise from intermolecular interactions described by several formalisms. These phenomena appear as deviations from the linearity of the respective van't Hoff plots. In solutions, molecular interactions manifest themselves in isoequilibrium relationships (IERs) as well as in a few cases of specific deviations of van't Hoff plots from linearity. The nature of these phenomena will be discussed on the basis of a statistical-thermodynamic model of spin crossover.
Synthesis and stability of wroewolfeite, Cu4SO4(OH)6·2H2O
Authors: Dabinett Timothy R. , Humberstone David , Leverett Peter , Williams Peter A. 
Published: June 2008

Abstract
Titration of aqueous copper(II) sulfate solutions with aqueous NaOH at temperatures ranging from 0 to 25 °C results in a complex Ostwald step rule cascade of basic copper sulfate phases. At 25 °C, the thermodynamically stable phase is brochantite [Cu4SO4(OH)6], but posnjakite [Cu4SO4(OH)6·H2O] is formed first. At lower temperatures, but above 0 °C, wroewolfeite [Cu4SO4(OH)6·2H2O] forms first. If left in contact with the reaction solution, wroewolfeite is converted to posnjakite and brochantite in turn. However, at 0 °C, synthetic wroewolfeite is stable for periods longer than a week, even in contact with the reaction solution, and a stability constant could be determined for its formation. For the reaction below, lg K = -16.3(1) at 0 °C and I = 0, as determined by solution methods.
0.25Cu4SO4(OH)6·2H2O(s,wroewolfeite) = Cu2+(aq) + 0.25SO4
2-(aq) + 1.5OH-(aq) + 0.5H2O(l)
Stability relations between minerals of stoichiometry Cu4SO4(OH)6·2H2O (n = 0, 1, 2) are discussed. High concentrations of Mg2+ ions (1 M) prevent the isolation of wroewolfeite at any temperature down to 0 °C.
Ternary mixtures of phosphonium ionic liquids + organic solvents + water
Authors: Chowdhury Shahana A. , Scott Janet L. , MacFarlane Douglas R. 
Published: June 2008

Abstract
Ionic liquids (ILs) and water are both potentially green solvents that are useful in a variety of extraction processes. This report presents the ternary phase diagrams and tie-line data of trihexyl(tetradecyl)phosphonium dicyanamide [P6,6,6,14][DCA], phosphonium bis(2,4,4-trimethylpentyl)phosphinate [P6,6,6,14][((CH3)3C5H8)2PO2], and 1-ethyl-3-methylimidazolium ethylsulfate [emim][C2H5SO4] ILs in organic solvents (ethanol, acetonitrile, toluene) and water. [P6,6,6,14][DCA] and [P6,6,6,14][((CH3)3C5H8)2PO2] tended to yield emulsions when combined with water and ethanol, while [emim][C2H5SO4] combined with toluene and water provided two clear phases of reasonable viscosity. The compositions of the ternary mixtures were determined to obtain the tie-lines. A noticeable difference was observed for the tie-lines of the same IL (e.g., [P6,6,6,14][DCA]) with different organic solvents (ethanol and acetonitrile) and water mixtures. In all cases, the addition of ethanol eventually produced a single phase.
3D-2D asymptotic analysis of an optimal design problem for thin films
Authors: Fonseca Irene , Francfort Gilles 
Published: June 2008

Abstract
The Gamma-limit of a rescaled version of an optimal material distribution problem for a cylindrical two-phase elastic mixture in a thin three-dimensional domain is explicitly computed. Its limit is a two-dimensional optimal design problem on the cross-section of the thin domain; it involves optimal energy bounds on two-dimensional mixtures of a related two-phase bulk material. Thus, it is shown in essence that 3D-2D asymptotics and optimal design commute from a variational standpoint.
Integral modular categories and integrality of quantum invariants at roots of unity of prime order
Authors: Masbaum G , Wenzl H 
Published: June 2008

Abstract
It is shown how to deduce integrality properties of quantum 3-manifold invariants from the existence of integral subcategories of modular categories. The method is illustrated in the case of the invariants associated to classical Lie algebras constructed in [42], showing that the invariants are algebraic integers provided the root of unity has prime order. This generalizes a result of [31], [32] and [29] in the sl2-case. We also discuss some details in the construction of invariants of 3-manifolds, such as the S-matrix in the PSUk case, and a local orientation reversal principle for the colored Homfly polynomial.
Invariant subspaces of given index in Banach spaces of analytic functions
Authors: Borichev Alexander 
Published: June 2008

Abstract
For a wide class of Banach spaces of analytic functions in the unit disc including all weighted Bergman spaces with radial weights and for weighted ℓAp spaces we construct z-invariant subspaces of index n, 2 ≦ n ≦ + ∞, without common zeros in the unit disc.
Sur la répartition des points rationnels de surfaces elliptiques
Authors: Billard Hervé 
Published: June 2008

Résumé
Nous étudions la répartition des points rationnels de surfaces elliptiques fibrées au dessus de la droite projective admettant une section. Nous déterminons la densité des points rationnels de telles surfaces dont un multiple appartient à une section. Dans le cas où la surface est birationnelle au plan projectif (sur le corps des rationnels), nous déduisons qu'il existe une infinité de fibres dont le rang est supérieur d'au moins une unité au rang générique.
Projective normality and syzygies of algebraic surfaces
Authors: Gallego F. J , Purnaprajna B. P 
Published: June 2008

Abstract
In this work we develop new techniques to compute Koszul cohomology groups for several classes of varieties. As applications we prove results on projective normality and syzygies for algebraic surfaces. From more general results we obtain in particular the following:
Mukai's conjecture (and stronger variants of it) regarding projective normality and normal presentation for surfaces with Kodaira dimension 0, and uniform bounds for higher syzygies associated to adjoint linear series,effective bounds along the lines of Mukai's conjecture regarding projective normality and normal presentation for surfaces of positive Kodaira dimension, and,results on projective normality for pluricanonical models of surfaces of general type (recovering and strengthening results by Ciliberto) and generalizations of them to higher syzygies.
In addition, we also extend the above results to singular surfaces.
Weights of Markov traces on Hecke algebras
Authors: Orellana R. C 
Published: June 2008

Abstract
We compute the weights, i.e. the values at the minimal idempotents, for the Markov trace on the Hecke algebra of type Bn and type Dn. In order to prove the weight formula, we define representations of the Hecke algebra of type B onto a reduced Hecke algebra of type A. To compute the weights for type D we use the inclusion of the Hecke algebra of type D into the Hecke algebra of type B.
Symplectic cutting of Kähler manifolds
Authors: Braverman Maxim 
Published: June 2008

Abstract
We obtain estimates on the character of the cohomology of an S1-equivariant holomorphic vector bundle over a Kähler manifold M in terms of the cohomology of the Lerman symplectic cuts and the symplectic reduction of M. In particular, we prove and extend inequalities conjectured by Wu and Zhang.
The proof is based on constructing a flat family of complex spaces Mt (t ∈ ℂ) such that Mt is isomorphic to M for t
≠ 0, while M0 is a singular reducible complex space, whose irreducible components are the Lerman symplectic cuts.
Homotopy colimits – comparison lemmas for combinatorial applications
Authors: Welker Volkmar , Ziegler Günter M , Živaljević Rade T 
Published: June 2008

Abstract
We provide a “toolkit” of basic lemmas for the comparison of homotopy types of homotopy colimits of diagrams of spaces over small categories. We show how this toolkit can be used in quite different fields of applications. We demonstrate this with respect to
Björner's “Generalized Homotopy Complementation Formula” [5],the topology of toric varieties,the study of homotopy types of arrangements of subspaces,the analysis of homotopy types of subgroup complexes.
A local-to-global principle for deformations of Galois representations
Authors: Böckle Gebhard 
Published: June 2008

Abstract
Given an absolutely irreducible Galois representation : GE → GLN (k), E a number field, k a finite field of characteristic l > 2, and a finite set of places Q of E containing all places above l and ∞ and all where ∞ ramifies, there have been defined many functors representing strict equivalence classes of deformations of such a representation, e.g. by Mazur or Wiles in [15] or [26], with various conditions on the behaviour of the deformations at the places in Q and with the condition that the deformations are unramified outside Q. Those functors are known to be representable. For as above, our goal is to present a rather general class of global deformation functors that satisfy local deformation conditions and to investigate for those, under what conditions the global deformation functor is determined by the local deformation functors.
We will give precise conditions under which the local functors for all places in Q are sufficient to describe the global functor, first in a coarse form, then in a refined form using auxiliary primes as done by Taylor and Wiles in [24]. This has several consequences. The strongest is that one can derive ring theoretic results for the universal deformation space by Mazur if one uses results of Diamond and Wiles, cf. [11] and [26], and if one has a good understanding of all local situations. Furthermore it is easier to understand what happens under increasing the ramification as done by Boston and Ramakrishna in [6] and [20], [21]. Finally we shall reinterpret the results in the case of a tame representation by directly considering presentations of certain pro-l Galois groups and revisiting the prime-to-adjoint principle of Boston, cf. [5].
Castelnuovo-Mumford regularity bound for smooth threefolds in ℙ5 and extremal examples
Authors: Kwak Si-Jong 
Published: June 2008

Abstract
Let X be a nondegenerate integral subscheme of dimension n and degree d in ℙN defined over the complex number field ℂ. X is said to be k-regular if Hi(ℙN, ℐX (k – i)) = 0 for all i ≧ 1, where ℐX is the sheaf of ideals of ℐℙN and Castelnuovo-Mumford regularity reg(X) of X is defined as the least such k. There is a well-known conjecture concerning k-regularity: reg(X) ≦ deg(X) – codim(X) + 1. This regularity conjecture including the classification of borderline examples was verified for integral curves (Castelnuovo, Gruson, Lazarsfeld and Peskine), and an optimal bound was also obtained for smooth surfaces (Pinkham, Lazarsfeld). It will be shown here that reg(X) ≦ deg(X) – 1 for smooth threefolds X in ℙ5 and that the only extremal cases are the rational cubic scroll and the complete intersection of two quadrics. Furthermore, every smooth threefold X in ℙ5 is k-normal for all k ≧ deg(X) – 4, which is the optimal bound as the Palatini 3-fold of degree 7 shows. The same bound also holds for smooth regular surfaces in ℙ4 other than for the Veronese surface.
Nicht-invasive Diagnostik kolorektaler Tumore – Hat der Guaiac-Test ausgedient? / Non-invasive detection of colorectal cancer – do we still need the guaiac-based fecal occult blood test?
Authors: Stein Jürgen , Loitsch Stefan M. , Shastri Yogesh 
Published: June 2008

Zusammenfassung
Aufgrund der leichten Handhabung und des Nachweises einer Mortalitätssenkung gilt der Nachweis von okkultem Blut (FOBT) im Stuhl derzeit als das am weitesten verbreitete Screeningverfahren für das kolorektale Karzinom. Als nachteilig erweisen sich allerdings eine unzureichende Sensitivität, insbesondere beim Nachweis früher Stadien und eine nach wie vor geringe Akzeptanz in der Bevölkerung. Vorläufige Daten zum Nachweis von Calprotectin oder der Tumor-M2-PK im Stuhl ließen bessere Screeningeigenschaften erwarten. Aber auch hier schränkt die geringe Sensitivität für frühe Vorstufen und unzureichende Spezifität mit zu erwartenden hohen Folgekosten die Tauglichkeit der Tests deutlich ein. Die kürzlich entwickelten immunologischen FOBTs (I-FOBT) erweisen sich als spezifischer und sensitiver. Sie beruhen auf dem Nachweis von humanem Hämoglobin mittels spezifischer Antikörper und sind somit unabhängig von diätetischen oder medikamentösen Faktoren, was zu einer deutlich besseren Akzeptanz führt. Sie gelten derzeit als kosteneffektivste Verfahren unter den nichtinvasiven Screeningmaßnahmen. Der Nachweis von Tumor-DNA im Stuhl eröffnet eine neue Ära zum frühzeitigen Nachweis kolorektaler Karzinome. Erste kleinere Studien weisen auf eine sehr gute Sensitivität dieser Verfahren hin. Sie lagen für kolorektale Karzinome zwischen 62–91% und für Adenome zwischen 26–73% bei mit 93–100% sehr guter Spezifität. Als nachteilig im Vergleich zu den derzeit verfügbaren Screeningtests erweisen sich allerdings die vergleichsweise hohen Kosten.
Determination of CD4 lymphocyte percentages using a new simplified and affordable no lyse flow cytometric protocol: a pilot study / Bestimmung der Lymphozyten-abhängigen CD4-Prozentwerte mit Hilfe eines neuen, vereinfachten und kostengünstigen, durchflusszytometrischen Protokolls ohne Lyse: Eine Testuntersuchung
Authors: Greve Burkhard , Cassens Uwe , Baumann Claudia , Sibrowski Walter , Kuling Gudrun , Szabados Florian , Schlenke Peter , Reichelt Doris , Gebauer Wolfgang , Göhde Wolfgang 
Published: June 2008

Abstract
Although the pathogenesis of HIV infection is independent of age, specific considerations have to be taken into account for the treatment of infants, children and adolescents. In addition to more cautious drug therapy, it is proposed to follow up disease progression by repeated measurement of CD4 lymphocyte percentage (CD4%). Unfortunately, this requires complicated, expensive analytical techniques and complex sample preparation protocols. This is one of the reasons why treatment of the increasing number of children suffering from HIV/AIDS in developing countries remains a challenge. We evaluated a new and simplified no lyse no wash protocol to measure CD4% on a volumetric flow cytometer. Eight blood samples of healthy and HIV-infected individuals were sent to five German hospital laboratories (centres B–F) and were measured by their flow cytometric in-house techniques. The results were compared to those of centre A using the volumetric technique with the new sample preparation protocol. Comparative data with established protocols and flow cytometric techniques showed good correlations for the determination of leukocytes and for lymphocytes. Comparing CD4% results of centre A (new protocol and volumetric measuring technique) with the highest and lowest values of centres B–F by Bland-Altman analysis yielded a bias of –1.02% (SD 3.16) and 4.27% (SD 3.72) over the whole range (4.01%–70.56%), respectively. A comparably simple three-step protocol as introduced for absolute CD4+ cell count can be used to calculate CD4% only by the addition of two antibodies (CD4 and CD45). The cost per test is in the range of €2.50 and therefore far below current prices of €15.00–€40.00.
Monitoring of CMV-specific T-cell levels after organ transplantation / Monitoring CMV-spezifischer T-Zellen nach Organtransplantation
Authors: Sester Martina , Gärtner Barbara C. , Sester Urban 
Published: June 2008

Abstract
Based on the systemic and life-long need for immunosuppressive drug therapy, patients after organ transplantation suffer from an increased risk of infectious complications and disease due to primary infection or reactivation with the human cytomegalovirus (CMV). In contrast, CMV infections in immunocompetent individuals are usually clinically silent. In recent years, significant advances have been made in the development of novel experimental approaches to quantify antigen-specific T-cells on the single cell level. These assays have been extensively characterised and evaluated as a novel diagnostic measure to analyse the individual immunocompetence towards CMV in a clinical setting. A close correlation was found between decreasing frequencies of CMV-specific T-cells and increasing viral load, whereas CMV-specific T-cells were stable in the absence of viral replication. Due to easy technical performance, limited sample volume and short processing times, the combined monitoring of CMV-specific T-cells and viral load represents a valuable diagnostic tool to identify patients at risk for CMV-related complications after organ transplantation.
Vergleichende Untersuchung verschiedener D-Dimer-Tests zum Ausschluss thromboembolischer Erkrankungen unter klinischen Routinebedingungen / Comparative evaluation of different D-dimer assays for exclusion of venous thromboembolism in a clinical routine setting
Authors: Roggenbuck Lennart , Dörner Klaus 
Published: June 2008

Zusammenfassung
In einer prospektiven Studie an 246 konsekutiven Ambulanzpatienten mit Verdacht auf thromboembolische Erkrankung (VTE) untersuchten wir das aktuelle Leistungsvermögen von vier D-Dimer-Tests (D-Dimer plus, Stratus CS, Innovance, alle Siemens Medical Solutions Diagnostics sowie Tina-quant D-Dimer, Roche Diagnostics) zum Ausschluss von VTE. Ausgangspunkt unserer Untersuchung war das Auftreten von drei falsch negativen D-Dimerbefunden bei Ambulanzpatienten mit gesicherter VTE innerhalb kürzerer Zeit.
Diagnostische Sensitivitäten und Spezifitäten sowie positive und negative prädiktive Werte der D-Dimer-Tests wurden auf Basis der herstellerempfohlenen Cut-off-Werte sowie der Obergrenze des jeweiligen 95%-Konfidenz-intervalls (95% CI) um diesen Cut-off berechnet.
Bei 46 Patienten (18,7%) ließ sich mit bildgebenden Verfahren eine VTE nachweisen. Der D-Dimer-plus-Test zeigte bei sieben (unter Berücksichtigung des 95% CI bei neun) von 46 Patienten falsch negative Ergebnisse (Sensitivität 84,8% bzw. 80,4%, negativer prädiktiver Wert 93,8% bzw. 93,0%) bei insgesamt niedriger Messsignaldynamik. Mit den drei alternativen Tests ließen sich in diesem Kollektiv keine falsch negativen Befunde nachweisen (Sensitivität und negativer prädiktiver Wert jeweils 100%).
Nur durch eine enge klinische Rückkopplung lassen sich Leistungsdefizite bereits etablierter Testsysteme erfassen. Bei entsprechendem Verdacht sind weitere Untersuchungen zur Klärung durch das Labor, auch in Übereinstimmung mit der aktuellen Akkreditierungsnorm DIN EN ISO 15189 zu fordern.