bluuebunny/crossref_metadata_2025_split huggingface dataset:
Conservative evaluation of the uncertainty in the LAGEOS-LAGEOS II Lense-Thirring test
Authors: Iorio Lorenzo 
Published: May 2009

Abstract
We deal with the test of the general relativistic gravitomagnetic Lense-Thirring effect currently being conducted in the Earth’s gravitational field with the combined nodes Ω of the laser-ranged geodetic satellites LAGEOS and LAGEOS II. One of the most important sources of systematic uncertainty on the orbits of the LAGEOS satellites, with respect to the Lense-Thirring signature, is the bias due to the even zonal harmonic coefficients J
ℓ of the multipolar expansion of the Earth’s geopotential which account for the departures from sphericity of the terrestrial gravitational potential induced by the centrifugal effects of its diurnal rotation. The issue addressed here is: are the so far published evaluations of such a systematic error reliable and realistic? The answer is negative. Indeed, if the difference ΔJ
ℓ among the even zonals estimated in different global solutions (EIGEN-GRACE02S, EIGEN-CG03C, GGM02S, GGM03S, ITG-Grace02, ITG-Grace03s, JEM01-RL03B, EGM2008, AIUB-GRACE01S) is assumed for the uncertainties δJ
ℓ instead of using their more-or-less calibrated covariances $$
\sigma _{J_\ell }
$$, it turns out that the systematic error δμ in the Lense-Thirring measurement is about 3 to 4 times larger than in the evaluations so far published based on the use of the covariances of one model at a time separately, amounting up to 37% for the pair EIGEN-GRACE02S/ITG-Grace03s. The comparison among the other recent GRACE-based models yields bias as large as about 25–30%. The major discrepancies still occur for J
4; J
6 and J
8, which are just to which the zonals the combined LAGEOS/LAGOES II nodes are most sensitive.
Bayes-optimal solution to inverse halftoning based on statistical mechanics of the Q-Ising model
Authors: Saika Yohei , Inoue Jun-ichi , Tanaka Hiroyuki , Okada Masato 
Published: May 2009

Abstract
On the basis of statistical mechanics of the Q-Ising model, we formulate the Bayesian inference to the problem of inverse halftoning, which is the inverse process of representing gray-scales in images by means of black and white dots. Using Monte Carlo simulations, we investigate statistical properties of the inverse process, especially, we reveal the condition of the Bayes-optimal solution for which the mean-square error takes its minimum. The numerical result is qualitatively confirmed by analysis of the infinite-range model. As demonstrations of our approach, we apply the method to retrieve a grayscale image, such as standard image Lena, from the halftoned version. We find that the Bayes-optimal solution gives a fine restored grayscale image which is very close to the original. In addition, based on statistical mechanics of the Q-Ising model, we are sucessful in constructing a practically useful method of inverse halftoning using the Bethe approximation.
Chemical evaluation of seeded fruit biomass of oil pumpkin (Cucurbita pepo L. var. Styriaca)
Authors: Košťálová Zuzana , Hromádková Zdenka , Ebringerová Anna 
Published: May 2009

AbstractOil pumpkin (Cucurbita pepo L. var. Styriaca) is an economically important horticultural plant cultivated for oil production. After harvesting seeds, the residual biomass has a limited application and is usually left in the field. An experimental study was performed to evaluate the chemical composition of the seeded fruit oil pumpkin biomass (OP) dried by solvent-exchange using ethanol. The sugar composition of polysaccharides obtained by sequential extraction with water and dilute alkali indicated the prevalence of pectic polysaccharides. Hemicelulloses were released in higher amounts in the alkaline step. The chemical composition of OP and its individual tissues (peel, flesh and hairy flesh) was investigated and compared to the corresponding preparations of standard pumpkin (SP, Cucurbita pepo L.). The content of components (on oven-dry basis), calculated from the analysis data of the individual tissues, was estimated for OP: 7.9 % ash, 7.6 % Klason lignin, 19.3 % pectin (as uronic acids), 34.1 % neutral carbohydrates, and 27.4 % α-cellulose and for SP: 6.4 % ash, 4.0 % Klason lignin, 20.9% pectin (as uronic acids), 38.1% neutral carbohydrates, and 29.2 % α-cellulose, respectively. The OP biomass showed a higher proportion of hemicelluloses.
Immobilization of porphyrins in poly(hydroxymethylsiloxane)
Authors: Šabata Stanislav , Hetflejš Jiří , Rychtáriková Renata , Kuncová Gabriela , Lang Kamil , Kubát Pavel 
Published: May 2009

AbstractThree tetracationic porphyrins differing in the position of charged nitrogen atoms on the peripheral substituents — 5,10,15,20-tetrakis(N-methylpyridinium-4-yl)porphyrin (TMPyP4), 5,10,15,20-tetrakis(N-methylpyridinium-2-yl)porphyrin (TMPyP2), 5,10,15,20-tetrakis(4-trimethylammoniophenyl) porphyrin (TMAPP), and hydrophobic 5,10,15,20-tetraphenylporphyrin (TPP), were immobilized by adsorption and encapsulation in poly(hydroxymethylsiloxane) (PHOMS). The so prepared porphyrin-PHOMS composites were characterized by porosimetry, scanning electron microscopy, fluorescence and diffuse reflectance UV-VIS spectroscopy. It was found that porphyrins are immobilized in the PHOMS matrix in the free base monomer form Their irradiation produced singlet oxygen O2(1Δg) with the lifetime of 10–30 μs.
Coupling of Two Partial Differential Equations and its Application, II — the Case of Briot–Bouquet Type PDEs —
Authors: Tahara Hidetoshi 
Published: May 2009

Let

F(t, x, u,v)

be a holomorphic function in a neighborhood of the origin of

ℂ^4

satisfying

F(0, x, 0, 0) ≡ 0

and

(∂F/∂v)(0,x, 0, 0) ≡ 0

; then the equation (A)

t∂u/∂t= F(t,x,u,∂u/∂x)

is called a Briot–Bouquet type partial differential equation, and the function

λ(x) = (∂F/∂u)(0,x, 0, 0)

is called the characteristic exponent. This paper considers a reduction of this equation (A) to a simple form (B)

t∂w/∂t = λ(x)w

under the assumption

λ(0) ∉ (−∞, 0]∪\{1, 2, . . .\}

. The reduction is done by considering the coupling of two equations (A) and (B), and by solving their coupling equations. The result is applied to the problem of finding all the singular solutions of (A).
Homogenized Spectral Problems for Exactly Solvable Operators: Asymptotics of Polynomial Eigenfunctions
Authors: Borcea Julius , Bøgvad Rikard , Shapiro Boris 
Published: May 2009

Consider a homogenized spectral pencil of exactly solvable linear differential operators

T_λ = \sum^k_{i=0} Q_i(z)λ^{k−i} \frac{d^i}{dz^i}

, where each

Q_i(z)

is a polynomial of degree at most

i

and

λ

is the spectral parameter. We show that under mild nondegeneracy assumptions for all sufficiently large positive integers

n

there exist exactly

k

distinct values

λ_{n,j}

,

1 ≤ j ≤ k

, of the spectral parameter

λ

such that the operator

T_λ

has a polynomial eigenfunction

p_{n,j}(z)

of degree

n

. These eigenfunctions split into

k

different families according to the asymptotic behavior of their eigenvalues. We conjecture and prove sequential versions of three fundamental properties: the limits

Ψ_j (z) = \lim_{n→∞} \frac{p'_{n,j}(z)}{λ_{n,j}p_{n,j}(z)}

exist, are analytic and satisfy the algebraic equation

\sum^k_{i=0} Qi(z)Ψ^i_j(z) = 0

almost everywhere in

ℂ ℙ^1

. As a consequence we obtain a class of algebraic functions possessing a branch near

∞ ∈ ℂ ℙ^1

which is representable as the Cauchy transform of a compactly supported probability measure.
Intersection Homology $\mathcal D$-Module and Bernstein Polynomials Associated with a Complete Intersection
Authors: Torrelli Tristan 
Published: May 2009

Let

X

be a complex analytic manifold. Given a closed subspace

Y\subset X

of pure codimension

p ≥ 1

, we consider the sheaf of local algebraic cohomology

H^p_{[Y]}(\mathcal O_X)

, and

\mathcal L(Y,X)\subset H^p_{[Y ]}(\mathcal O_X)

the intersection homology

\mathcal D_X

-Module of Brylinski–Kashiwara. We give here an algebraic characterization of the spaces

Y

such that

\mathcal L(Y,X)

coincides with

H^p_{[Y]}(\mathcal O_X)

, in terms of Bernstein–Sato functional equations.
The Energy of Charge‐Transfer States in Electron Donor–Acceptor Blends: Insight into the Energy Losses in Organic Solar Cells
Authors: Veldman Dirk , Meskers Stefan C. J. , Janssen René A. J. 
Published: May 2009

AbstractHere, a general experimental method to determine the energy ECT of intermolecular charge‐transfer (CT) states in electron donor–acceptor (D–A) blends from ground state absorption and electrochemical measurements is proposed. This CT energy is calibrated against the photon energy of maximum CT luminescence from selected D–A blends to correct for a constant Coulombic term. It is shown that ECT correlates linearly with the open‐circuit voltage (Voc) of photovoltaic devices in D–A blends via eVoc = ECT − 0.5 eV. Using the CT energy, it is found that photoinduced electron transfer (PET) from the lowest singlet excited state (S1 with energy Eg) in the blend to the CT state (S1 → CT) occurs when Eg − ECT > 0.1 eV. Additionally, it is shown that subsequent charge recombination from the CT state to the lowest triplet excited state (ET) of D or A (CT → T1) can occur when ECT − ET > 0.1 eV. From these relations, it is concluded that in D–A blends optimized for photovoltaic action: i) the maximum attainable Voc is ultimately set by the optical band gap (eVoc = Eg − 0.6 eV) and ii) the singlet–triplet energy gap should be ΔEST < 0.2 eV to prevent recombination to the triplet state. These favorable conditions have not yet been met in conjugated materials and set the stage for further developments in this area.
Linear clinical progression, independent of age of onset, in Niemann–Pick disease, type C
Authors: Yanjanin Nicole M. , Vélez Jorge I. , Gropman Andrea , King Kelly , Bianconi Simona E. , Conley Sandra K. , Brewer Carmen C. , Solomon Beth , Pavan William J. , Arcos‐Burgos Mauricio , Patterson Marc C. , Porter Forbes D. 
Published: May 2009

AbstractNiemann–Pick disease, type C is a neurodegenerative, lysosomal storage disorder with a broad clinical spectrum and a variable age of onset. The absence of a universally accepted clinical outcome measure is an impediment to the design of a therapeutic trial for NPC. Thus, we developed a clinical severity scale to characterize and quantify disease progression. Clinical signs and symptoms in nine major (ambulation, cognition, eye movement, fine motor, hearing, memory, seizures, speech, and swallowing) and eight minor (auditory brainstem response, behavior, gelastic cataplexy, hyperreflexia, incontinence, narcolepsy, psychiatric, and respiratory problems) domains were scored. Data were collected from 18 current NPC patients and were extracted from records of 19 patients. Both patient cohorts showed a linear increase in severity scores over time. Cross‐sectional evaluation of current patients showed a linear increase in the severity score. Longitudinal chart review of historical data demonstrated that although age of onset varied significantly, the rate of progression appeared linear, independent of age of onset, and similar in all patients. Combining the data from both cohorts, disease progression could be modeled by the following equation: Ŝt0+x = Ŝt0 + 1.87x; where Ŝt0 is the initial score and Ŝt0+x is the predicted future score after x years. Our observation that disease progression is similar across patients and independent of age of onset is consistent with a biphasic pathological model for NPC. This scale may prove useful in the characterization of potential biomarkers, and as an outcome measure to monitor disease progression in NPC patients. © 2009 Wiley‐Liss, Inc.
Bindungsmechanismen in supramolekularen Komplexen
Authors: Schneider Hans‐Jörg 
Published: May 2009

AbstractKräfte‐Sammelsurium: Supramolekulare Komplexe, wie der gezeigte, beruhen meist auf einer Kombination unterschiedlichster Wechselwirkungen, wie Ionenpaarbildung, Wasserstoffbrücken und Stapelwechselwirkungen. Die nicht immer einfache Charakterisierung von Natur und Stärke der intermolekularen Kräfte liefert Beiträge zum Verständnis biomimetischer Systeme wie auch zum Design von synthetischen Rezeptoren, Wirkstoffen und intelligenten Materialien.magnified imageDie supramolekulare Chemie hat in den letzten Jahren eine enorme Ausdehnung erfahren, sowohl mit Blick auf mögliche Anwendungen wie auch auf analoge biologische Systeme. Bildung und Funktion supramolekularer Komplexe werden durch eine Vielzahl von oft schwer zu differenzierenden nichtkovalenten Kräften bestimmt. Ziel dieses Aufsatzes ist es, die entscheidenden Wechselwirkungsmechanismen zusammenhängend darzustellen und das Gesamtgebiet auf diese Weise zu klassifizieren. Als Beispiele werden meist organische Wirt‐Gast‐Komplexe gewählt, unter Berücksichtigung auch von biologisch relevanten Fragestellungen. Das Verständnis und die Quantifizierung der intermolekularen Wechselwirkungen ist für die rationale Planung neuer supramolekularer Systeme, einschließlich intelligenter Materialien, ebenso von Bedeutung wie für die Entwicklung neuer Wirkstoffe.
Enantioselective Synthesis of β‐Iodo Morita–Baylis–Hillman Esters by a Catalytic Asymmetric Three‐Component Coupling Reaction
Authors: Senapati Bidyut Kumar , Hwang Geum‐Sook , Lee Sungil , Ryu Do Hyun 
Published: May 2009

AbstractDie katalytische asymmetrische Kupplung von α,β‐acetylenischen Estern mit Aldehyden und Trimethylsilyliodid führt zu chiralen Morita‐Baylis‐Hillman‐Estern (siehe Schema, TMS=Trimethylsilyl). Die Reaktion verläuft äußerst enantioselektiv, und die Produkte lassen sich unter Erhaltung der Konfiguration in einem einzigen Schritt in β‐verzweigte Derivate umwandeln.magnified image
Stereoselektive Pd‐katalysierte Carboaminoxylierung von Indolen mit Arylboronsäuren und TEMPO
Authors: Kirchberg Sylvia , Fröhlich Roland , Studer Armido 
Published: May 2009

AbstractWer A sagt, muss auch B sagen! Indole reagieren mit Arylboronsäuren in chemodivergenter Weise: Freies Indol und N‐Methylindol führen durch direkte C‐H‐Arylierung hauptsächlich zu den C(2)‐arylierten Indolen A, während N‐acylierte, N‐benzoylierte und N‐Boc‐geschützte Indole das arylcarboaminoxylierte Produkt B hoch diastereoselektiv in guten Ausbeuten ergeben.magnified image
Coherent Multidimensional Vibrational Spectroscopy of Biomolecules: Concepts, Simulations, and Challenges
Authors: Zhuang Wei , Hayashi Tomoyuki , Mukamel Shaul 
Published: May 2009

AbstractGood vibrations: The vibrational response of complex molecules to sequences of infrared pulses provides novel femtosecond snapshots of their structure and dynamics. This technique, which is the optical analogue of multidimensional NMR spectroscopy, gives correlation plots of motions during controlled time intervals between pulses that are applied to study protein folding, chirality, hydrogen‐bonding, phospholipid membranes, and chemical exchange.magnified imageThe response of complex molecules to sequences of femtosecond infrared pulses provides a unique window into their structure, dynamics, and fluctuating environments. Herein we survey the basic principles of modern two‐dimensional infrared (2DIR) spectroscopy, which analogous to those of multidimensional NMR spectroscopy. The perturbative approach for computing the nonlinear optical response of coupled localized chromophores is introduced and applied to the amide backbone transitions of proteins, liquid water, membrane lipids, and amyloid fibrils. The signals are analyzed using classical molecular dynamics simulations combined with an effective fluctuating Hamiltonian for coupled localized anharmonic vibrations whose dependence on the local electrostatic environment is parameterized by an ab initio map. Several simulation methods, (cumulant expansion of Gaussian fluctuation, quasiparticle scattering, the stochastic Liouville equations, direct numerical propagation) are surveyed. Chirality‐induced techniques which dramatically enhance the resolution are demonstrated. Signatures of conformational and hydrogen‐bonding fluctuations, protein folding, and chemical‐exchange processes are discussed.
Binding Mechanisms in Supramolecular Complexes
Authors: Schneider Hans‐Jörg 
Published: May 2009

AbstractForces to reckon with: Supramolecular complexes, such as the one shown, are normally based on a combination of different interactions such as ion pairing, hydrogen bonds, and stacking interactions. The not always simple characterization of the nature and strength of intermolecular forces provides assistance to the understanding of biomimetic systems, as well as for the design of synthetic receptors, drugs, and intelligent materials.magnified imageSupramolecular chemistry has expanded dramatically in recent years both in terms of potential applications and in its relevance to analogous biological systems. The formation and function of supramolecular complexes occur through a multiplicity of often difficult to differentiate noncovalent forces. The aim of this Review is to describe the crucial interaction mechanisms in context, and thus classify the entire subject. In most cases, organic host–guest complexes have been selected as examples, but biologically relevant problems are also considered. An understanding and quantification of intermolecular interactions is of importance both for the rational planning of new supramolecular systems, including intelligent materials, as well as for developing new biologically active agents.
Sequencing Single DNA Molecules in Real Time
Authors: Ibach Jenny , Brakmann Susanne 
Published: May 2009

AbstractOne's enough: The direct observation of a DNA‐polymerase‐based “sequencing engine” using single‐molecule detection recently allowed single‐molecule sequencing by synthesis in real time. Nucleotides with a fluorescent marker at the 5′‐phosphate unit and zero‐mode waveguides are crucial components of this approach, which at last promises low‐cost genome‐scale sequencing.magnified image
Stereoselective Palladium‐Catalyzed Carboaminoxylations of Indoles with Arylboronic Acids and TEMPO
Authors: Kirchberg Sylvia , Fröhlich Roland , Studer Armido 
Published: May 2009

AbstractIndoles are not indolent: Various indoles react with arylboronic acids chemodivergently. CH arylation of free indole and N‐methylindole gives the corresponding C(2)‐arylated indoles A whereas N‐acylated, N‐benzoylated, and N‐Boc‐protected indoles provide the corresponding arylcarboaminoxylated products B with excellent diastereoselectivity in good to excellent yields.magnified image
Simulation of dry‐spinning process of polyimide fibers
Authors: Deng Gang , Xia Qingming , Xu Yuan , Zhang Qinghua 
Published: May 2009

AbstractAs one type of high‐performance fibers, the polyimide fibers can be prepared from the precursor polyamic acid via dry‐spinning technology. Unlike the dry‐spinning process of cellulose acetate fiber or polyurethane fiber, thermal cyclization reaction of the precursor in spinline with high temperature results in the relative complex in the dry‐spinning process. However, the spinning process is considered as a steady state due to a slight degree of the imidization reaction from polyamic acid to polyimide, and therefore a one‐dimensional model based on White‐Metzer viscoelastic constitutive equation is adopted to simulate the formation of the fibers. The changes of solvent mass fraction, temperature, axial velocity, tensile stress, imidization degree, and glass transition temperature of the filament along the spinline were predicted. The effects of spinning parameters on glass transition temperature and imidization degree were thus discussed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
An effective method to identify the type and content of α‐olefin in polyolefine copolymer by Fourier Transform Infrared–Differential Scanning Calorimetry
Authors: Zhang Qing , Chen Ping , Xie Xiaoli , Cao Xianwu 
Published: May 2009

AbstractA new method for identification of ethylene/α‐olefin copolymer was established by Fourier Transform Infared (FTIR)–Differential Scanning Calorimetery (DSC) in this article. DSC and FTIR spectroscopy techniques were used to analysis the type and content of α‐olefin in polyolefine copolymer. FTIR was available to identify the structures of polyethylene and copolymers of ethylene with different α‐olefins. The type of polyethylene can be determined by the peak position of 1378 and 1369 cm−1. According to the peak location of 770, 784, and 895 cm−1, the type of α‐olefin can also be determined. DSC method was used to decide the position of melting peaks. The quantitative investigation of the content of α‐olefin in polyethylene was calculated by the formula: −ln(CH2 mol fraction) = −0.331+135.5/Tm. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Crosslinking and stabilization of nanoparticle filled poly(1‐trimethylsilyl‐1‐propyne) nanocomposite membranes for gas separations
Authors: Shao Lei , Samseth Jon , Hägg May‐Britt 
Published: May 2009

AbstractPoly(1‐trimethylsilyl‐1‐propyne) (PTMSP) has been crosslinked using 4,4′‐diazidobenzophenone bisazide to improve its chemical and physical stability over time. Crosslinking PTMSP renders it insoluble in good solvents for the uncrosslinked polymer. Gas permeability and fractional free volume decreased as crosslinker content increased, while gas sorption was unaffected by crosslinking. Therefore, the reduction in permeability upon crosslinking PTMSP was due to decrease in diffusion coefficient. Compared with the pure PTMSP membrane, the permeability of the crosslinked membrane is initially reduced for all gases tested due to the crosslinking. By adding nanoparticles (fumed silica, titanium dioxide), the permeability is again increased; permeability reductions due to crosslinking could be offset by adding nanoparticles to the membranes. Increased selectivity is documented for the gas pairs O2/N2, H2/N2, CO2/N2, CO2/CH and H2/CH4 using crosslinking and addition of nanoparticles. Crosslinking is successful in maintaining the permeability and selectivity of PTMSP membranes and PTMSP/filler nanocomposites over time. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Flexural behavior of asymmetric structural foams
Authors: Barzegari M. Reza , Rodrigue Denis 
Published: May 2009

AbstractAsymmetric structural foams were prepared by compression molding to study the flexural properties of these sandwich structures with different layer thickness. It was found that the flexural properties of asymmetric structural foams are function of load direction. Since the bending behavior is a combination of tension and compression, the stress distribution across the foam core plays a key role in describing their bending properties. The experimental results show that the compression modulus of integral foams is lower than its tensile modulus. Based on this information, a model is proposed to predict the flexural properties of asymmetric structural foams based on stress distribution. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis and Studies of New 2‐(Coumarin‐4‐yloxy)‐4,6‐(substituted)‐s‐Triazine Derivatives as Potential Anti‐HIV Agents
Authors: Mahajan Dharmesh H. , Pannecouque Christophe , De Clercq Erik , Chikhalia Kishor H. 
Published: May 2009

AbstractNovel 2‐(coumarin‐4‐yloxy)‐4,6‐(substituted)‐s‐triazine derivatives i. e., diaryltriazine (DATA) are reported as novel non‐nucleoside reverse transcriptase inhibitors (NNRTIs), were synthesized and their activities against human immunodeficiency virus HIV‐1 (III‐B), HIV‐2 (ROD), and the double RT mutant HIV‐1 (K103N and Y181C) were assessed. Modifications at positions 4 and 6 of the coumarinyl‐triazine scaffold generated interesting derivatives displaying good to moderate anti‐HIV activity against selected HIV strains as compared to nevirapine and efavirenz. The synthesized compounds were characterized by FTIR, 1H‐NMR, and mass spectral data together with elemental analysis.