bluuebunny/crossref_metadata_2025_split huggingface dataset:
Density functional theory‐based electrochemical models for the oxygen reduction reaction: Comparison of modeling approaches for electric field and solvent effects
Authors: Yeh Kuan‐Yu , Janik Michael J. 
Published: September 2011

AbstractA series of density functional theory (DFT) based electrochemical models are applied to systematically examine the effect of solvent, local electric field, and electrode potential on oxygen reduction reaction (ORR) kinetics. Specifically, the key elementary reaction steps of molecular oxygen dissociation, molecular oxygen protonation, and reduction of a hydroxyl adsorbate to water over the Pt(111) surface were considered. The local electric field has slight influence on reaction energetics at the vacuum interface. Solvent molecules stabilize surface adsorbates, assisting oxygen reduction. A collective solvation‐potential coupled effect is identified by including long range solvent‐solvent interactions in the DFT model. The dominant path of the ORR reaction varies with electrode potential and among the modeling approaches considered. The potential dependent reaction path determined from the solvated model qualitatively agrees with experiment ORR kinetics. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011
Application of analytical electron microscopic methods to investigate the function of spherites in the midgut of the larval antlion Euroleon nostras (Neuroptera: Myrmeleontidae)
Authors: Lipovšek Saška , Letofsky‐Papst Ilse , Hofer Ferdinand , Pabst Maria Anna , Devetak Dušan 
Published: September 2011

AbstractThis study presents an application of analytical electron microscopy in biology to investigate the chemical composition of the spherites and to elucidate the importance of these methods in the life sciences. The structure of the spherites in the midgut cells of first, second, and third instar larvae Euroleon nostras was investigated by a combination of transmission electron microscopy (TEM), energy dispersive X‐ray spectroscopy (EDXS), electron energy‐loss spectroscopy (EELS), and energy filtering TEM (EFTEM). The structure and chemical composition of the spherites changed during the metamorphosis. In first larvae, the spherites are composed of amorphous, flocculent material, containing C, N, and O. In second larvae and third ones, the spherites have concentric layers of alternating electron‐dense and electron‐lucent material. In second larvae, Si, P, Ca, and Fe are accumulated in the spherite organic matrix, composed of C, N, and O. In the spherites of third larvae, additionally Al was found. Therefore, the spherites are thought to store organic compounds in all three larval stages of E. nostras and additionally inorganic compounds in second and third ones. In first larvae, spherites are present in the midgut cells; in second and third larvae, they are present in the cells of the midgut and in its lumen. It could be suggested that the spherites might be involved in the regulation of the appropriate mineral composition of the internal environment and could serve as the accumulation site of nontoxic waste materials that cannot be metabolized. Microsc. Res. Tech., 2011. © 2011 Wiley‐Liss, Inc.
Immunohistochemical detection and quantification of T cells in the small intestine of Isospora suis‐infected piglets—influence of fixation technique and intestinal segment
Authors: Gabner Simone , Tonar Zbyněk , Tichy Alexander , Saalmüller Armin , Worliczek Hanna Lucia , Joachim Anja , Witter Kirsti 
Published: September 2011

AbstractQuantification of immunohistochemical results constitutes an important tool in the analysis of cells and tissue that is not readily replaced by other techniques. For reliable quantification, it is essential to consider factors such as tissue fixation and tissue sampling. We report a study on the model of the intestine of Isospora suis‐infected piglets, in which we addressed (1) whether the quantity of detectable T cells in the intestinal mucosa is the same in formalin‐, HOPE®‐, and cryo‐conserved material or whether the amounts of T cells at least correlate with one another; and (2) whether single jejunal segments differ in regard to the quantity of mucosal T cells and variability of lymphocyte infiltration. Quantification of T cells in histological sections of different parts of the jejunum of 15‐22 day old piglets infected with I. suis was performed using an anti‐CD3‐antibody and stereological point counting. Area fractions of T‐cell profiles per intestinal mucosa profile were higher in cryo‐conserved samples than in HOPE®‐ and formalin‐conserved material but no correlation between different fixations could be found. The proximal part of the jejunum contained fewer T cells compared with mid‐ and end‐jejunum. Coefficients of variation did not differ between the intestinal segments. For quantification of T cells in the gut mucosa of piglets infected with I. suis, the cryo‐conserved mid jejunum seems most suitable in cases when unbiased sampling of the complete intestine is not feasible. It is generally not possible to compare quantitative results of immunostaining in samples conserved by different methods. Microsc. Res. Tech., 2011. © 2011 Wiley‐Liss, Inc.
EMG‐driven modeling approach to muscle force and joint load estimations: Case study in knee osteoarthritis
Authors: Kumar Deepak , Rudolph Katherine S. , Manal Kurt T. 
Published: September 2011

AbstractIt is important to know the magnitude and patterns of joint loading in people with knee osteoarthritis (OA), since altered loads are implicated in onset and progression of the disease. We used an EMG‐driven forward dynamics model to estimate joint loads during walking in a subject with knee OA and a healthy control subject. Kinematic, kinetic, and surface EMG data were used to predict muscle forces using a Hill‐type muscle model. The muscle forces were used to balance the frontal plane moment to obtain medial and lateral condylar loads. Loads were normalized to body weight (BWs) and the mean of three trials taken. The OA subject had greater medial and lower lateral loads compared to the control subject. Seventy‐five to 80% of the total load was borne on the medial compartment in the control subject, compared to 90–95% in the OA subject. In fact, complete lateral unloading occurred during midstance for the OA subject. Loading for the healthy subject was consistent with the data from instrumented knee studies. In the future, the model can be used to analyze the impact of various interventions to reduce the loads on the medial compartment in people with knee OA. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 30:377–383, 2012
North Atlantic climate impact on early late‐glacial climate oscillations in the south‐eastern Alps inferred from a multi‐proxy lake sediment record
Authors: Schmidt Roland , Weckström Kaarina , Lauterbach Stefan , Tessadri Richard , Huber Kerstin 
Published: September 2011

AbstractHigh‐resolution multi‐proxy analyses of a sediment core section from Lake Jeserzersee (Saissersee) in the piedmont lobe of the Würmian Drau glacier (Carinthia, Austria) reveal pronounced climatic oscillations during the early late glacial (ca. 18.5–16.0k cal a BP). Diatom‐inferred epilimnetic summer water temperatures show a close correspondence with temperature reconstructions from the adjacent Lake Längsee record and, on a hemispheric scale, with fluctuations of ice‐rafted debris in the North Atlantic. This suggests that North Atlantic climate triggered summer climate variability in the Alps during the early late glacial. The expansion of pine (mainly dwarf pine) between ca. 18.5 and 18.1k cal a BP indicates warming during the so‐called ‘Längsee oscillation’. The subsequent stepwise climate deterioration between ca. 18.1 and 17.6k cal a BP culminated in a tripartite cold period between ca. 17.6 and 16.9k cal a BP with diatom‐inferred summer water temperatures 8.5–10 °C below modern values and a shift from wet to dry conditions. This period probably coincides with a major Alpine glacier advance termed the Gschnitz stadial. A warmer interval between ca. 16.9 and 16.4k cal a BP separates this cold phase from a second, shorter and less pronounced cold phase between ca. 16.4 and 16.0k cal a BP, which is thought to correlate with the Clavadel/Senders glacier advance in the Alps. The following temperature increase, coupled with wet (probably snow‐rich) conditions, caused the expansion of birch during the transition period to the late glacial interstadial. Copyright © 2011 John Wiley & Sons, Ltd.
A Facile Approach to Fabricate Self‐Standing Gel‐Polymer Electrolytes for Flexible Lithium‐Ion Batteries by Exploitation of UV‐Cured Trivalent/Monovalent Acrylate Polymer Matrices
Authors: Kil Eun‐Hye , Ha Hyo‐Jeong , Lee Sang‐Young 
Published: September 2011

AbstractA facile approach to fabricate a self‐standing GPE for flexible lithium‐ion batteries is demonstrated using a UV‐cured trivalent/monovalent acrylate polymer matrix and a liquid electrolyte. The polymer matrix is successfully synthesized with the co‐presence of the liquid electrolyte by UV polymerization of ETPTA, which has trivalent vinyl groups, and EGMEA, which contains monovalent vinyl groups, with the ETPTA/EGMEA ratio fixed at 90/10 (wt%/wt%). The ETPTA/EGMEA matrix shows a lower Tg than the ETPTA matrix alone, which helps improve the mechanical flexibility and ionic transport of the resulting GPE. These features of the ETPTA/EGMEA‐based GPE, together with its superior interfacial compatibility towards electrodes, play crucial roles in obtaining a better cell performance compared to the ETPTA‐based GPE.
Tunable Arrangement of Gold Nanoparticles in Epoxidated Poly(styrene‐block‐butadiene) Diblock Copolymer Matrices
Authors: Kuo Shiao‐Wei , Yang Hong‐Ying 
Published: September 2011

AbstractA new approach to synthesize block‐copolymer‐mediated/gold nanoparticle (Au NP) composites is developed. Stable and narrowly distributed Au NPs modified with a 2‐phenylethanethiol ligand are prepared by a two‐phase liquid–liquid method. A new epoxidation of a poly(styrene‐block‐butadiene) diblock copolymer, to form poly(styrene‐block‐vinyl oxirane) (PS‐b‐PBO), is achieved through chemical modification. It is found that the Au NPs disperse well in the PS block segment by partially crosslinking the PBO block segment with poly(ethylene oxide bisamine) (D230), a curing agent. The aggregation of Au NPs leads to a red‐shift of the plasmon absorption with the increase in the D230 content. However, without crosslinking the PBO block segment with D230, Au NPs distributes in both the PS and PBO segments.
On the X‐rank with respect to linear projections of projective varieties
Authors: Ballico Edoardo , Bernardi Alessandra 
Published: September 2011

AbstractIn this paper we improve the known bound for the X‐rank RX(P) of an element \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$P\in {\mathbb {P}}^N$\end{document} in the case where \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$X\subset {\mathbb P}^n$\end{document} is a projective variety obtained as a linear projection from a general v‐dimensional subspace \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$V\subset {\mathbb P}^{n+v}$\end{document}. Then, if \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$X\subset {\mathbb P}^n$\end{document} is a curve obtained from a projection of a rational normal curve \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$C\subset {\mathbb P}^{n+1}$\end{document} from a point \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$O\subset {\mathbb P}^{n+1}$\end{document}, we are able to describe the precise value of the X‐rank for those points \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$P\in {\mathbb P}^n$\end{document} such that RX(P) ≤ RC(O) − 1 and to improve the general result. We also give a stratification, via the X‐rank, of the osculating spaces to projective cuspidal projective curves X. We give a description and a new bound of the X‐rank of subspaces both in the general case and with respect to integral non‐degenerate projective curves.
On notion of asymptotic derivations
Authors: Heo Jaeseong 
Published: September 2011

AbstractIn this paper we introduce some notion of asymptotic derivations of a C*‐ and W*‐dynamical systems which naturally arises from a one‐parameter group of automorphisms. We show that an asymptotic derivation on a unital simple C*‐algebra or a von Neumann algebra is asymptotically inner. Every asymptotic derivation on finite dimensional C*‐algebras is induced by an inner derivation. We prove that any asymptotic derivation on commutative von Neumann algebras have a strong limit zero. An asymptotic derivation on the hyperfinite II1‐factor given by some one‐parameter group of automorphisms can be induced by a (inner) derivation. Finally, we show that every asymptotic Jordan derivation of a C*‐dynamical system is an asymptotic derivation and is also induced by a derivation if there exists a limit.
Deciphering the Structural Requirements of Nucleoside Bisubstrate Analogues for Inhibition of MbtA in Mycobacterium tuberculosis: A FB‐QSAR Study and Combinatorial Library Generation for Identifying Potential Hits
Authors: Maganti Lakshmi , Das Sanjit Kumar , Mascarenhas Nahren Manuel , Ghoshal Nanda 
Published: September 2011

AbstractThe re‐emergence of tuberculosis infections, which are resistant to conventional drug therapy, has steadily risen in the last decade. Inhibitors of aryl acid adenylating enzyme known as MbtA, involved in siderophore biosynthesis in Mycobacterium tuberculosis, are being explored as potential antitubercular agents. The ability to identify fragments that interact with a biological target is a key step in fragment based drug design (FBDD). To expand the boundaries of quantitative structure activity relationship (QSAR) paradigm, we have proposed a Fragment Based QSAR methodology, referred here in as FB‐QSAR, for deciphering the structural requirements of a series of nucleoside bisubstrate analogs for inhibition of MbtA, a key enzyme involved in siderophore biosynthetic pathway. For the development of FB‐QSAR models, statistical techniques such as stepwise multiple linear regression (SMLR), genetic function approximation (GFA) and GFAspline were used. The predictive ability of the generated models was validated using different statistical metrics, and similarity‐based coverage estimation was carried out to define applicability boundaries. To aid the creation of novel antituberculosis compounds, a bioisosteric database was enumerated using the combichem approach endorsed mining in a lead‐like chemical space. The generated library was screened using an integrated in‐silico approach and potential hits identified.
Alkaloids from Hippeastrum morelianum Lem. (Amaryllidaceae)
Authors: Giordani Raquel B. , de Andrade Jean P. , Verli Hugo , Dutilh Julie H. , Henriques Amélia T. , Berkov Strahil , Bastida Jaume , Zuanazzi José Angelo S. 
Published: September 2011

AbstractThe Amaryllidaceae family has proven to be a rich source of active molecules. As part of an ongoing project, we report a phytochemical study of Hippeastrum morelianum (Amaryllidaceae), from which we have isolated two homolycorine‐type alkaloids, the new 2α,7‐dimethoxyhomolycorine (1) and the poorly described candimine (2), as well as six known alkaloids: tazettine, pretazettine, 3‐epimacronine, haemanthamine, hamayne and trisphaeridine. For reference purposes, the NMR of the isolated compounds was unequivocally described, based on 2D NMR measurements including 1H–1H COSY, 1H–1H NOESY, HSQC and HMBC. Copyright © 2011 John Wiley & Sons, Ltd.
Silencing disease genes in the laboratory and the clinic
Authors: Watts Jonathan K , Corey David R 
Published: September 2011

AbstractSynthetic nucleic acids are commonly used laboratory tools for modulating gene expression and have the potential to be widely used in the clinic. Progress towards nucleic acid drugs, however, has been slow and many challenges remain to be overcome before their full impact on patient care can be understood. Antisense oligonucleotides (ASOs) and small interfering RNAs (siRNAs) are the two most widely used strategies for silencing gene expression. We first describe these two approaches and contrast their relative strengths and weaknesses for laboratory applications. We then review the choices faced during development of clinical candidates and the current state of clinical trials. Attitudes towards clinical development of nucleic acid silencing strategies have repeatedly swung from optimism to depression during the past 20 years. Our goal is to provide the information needed to design robust studies with oligonucleotides, making use of the strengths of each oligonucleotide technology. Copyright © 2011 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Monitoring of Phenolic Compounds for the Quality Control of Melissa officinalis Products by Capillary Electrophoresis
Authors: Acosta Gimena , Arce Silvia , Martínez Luis D. , Llabot Juan , Gomez María R. 
Published: September 2011

ABSTRACTIntroductionOfficial assays for the quality control of Melissa officinalis L. (Lamiaceae) leaves establish the quantification of total hydroxycinnamic derivatives expressed as rosmarinic acid.ObjectiveThe goal of this work was to develop a simple, fast and reliable method for monitoring the phenolic composition in herbs from the Lamiaceae family and for rapidly detecting M. officinalis adulteration or substitution in commercial medicinal samples in Argentina.MethodologyA capillary zone electrophoresis (CZE) method was performed under the following conditions: the background electrolyte (BGE) consisted of 20 m m sodium tetraborate buffer, pH 9.2; the applied voltage was 25 kV; the capillary and sample temperatures were kept at 25 °C; the hydrodynamic mode was selected for the sample injection (3.45 kPa during 5 s).ResultsA CZE method that achieved the separation and simultaneous determination of eight related phenolic compounds in less than 11 min was optimised for application to control quality analysis of M. officinalis‐based products. The method was validated according to the US Federal Drug Agency requirements and offers advantages in terms of analysis time, cost and operation.ConclusionsThe proposed methodology can be applied to the standardisation and quality control of plant material and phytopharmaceutical products derived from the Lamiaceae family, as indicated by the results obtained in the analysis of commercial medicinal products in Argentina. Copyright © 2011 John Wiley & Sons, Ltd.
HPLC Determination of Flavonoid Glycosides in Mongolian Dianthus versicolorFisch. (Caryophyllaceae) Compared with Quantification by UV Spectrophotometry
Authors: Obmann Astrid , Purevsuren Sodnomtseren , Zehl Martin , Kletter Christa , Reznicek Gottfried , Narantuya Samdan , Glasl Sabine 
Published: September 2011

ABSTRACTIntroductionDianthus versicolor is used in traditional Mongolian medicine against liver impairment. Fractions enriched in flavone‐di‐ and triglycosides were shown to enhance bile secretion. Therefore, reliable and accurate analytical methods are needed for the determination of these flavonoids in the crude drug and extracts thereof.ObjectiveTo provide a validated HPLC‐DAD (diode array detector) method especially developed for the separation of polar flavonoids and to compare the data obtained with those evaluated by UV spectrophotometry.MethodologySeparations were carried out on an Aquasil® C18‐column (4.6 mm × 250.0 mm, 5 µm) with a linear gradient of acetonitrile and water (adjusted to pH 2.8 with trifluoroacetic acid) as mobile phase. Rutoside was employed as internal standard with linear behavior in a concentration range of 0.007–3.5 mg/mL. Accuracy was determined by spiking the crude drug with saponarin resulting in recoveries between 92% and 102%.ResultsThe method allows the quantification of highly polar flavonoid glycosides and the determination of their total content. For saponarin a linear response was evaluated within the range 0.007–3.5 mg/mL (R2 > 0.9999). It was proven that threefold sonication represents a time‐saving, effective and cheap method for the extraction of the polar flavonoid glycosides. The contents determined by HPLC were shown to be in agreement with those obtained employing UV spectrophotometry.ConclusionThe study has indicated that the newly developed HPLC method represents a powerful technique for the quality control of D. versicolor. Ultraviolet spectrophotometry may be used alternatively provided that the less polar flavonoids are removed by purification. Copyright © 2011 John Wiley & Sons, Ltd.
The Use of Coupled HSQC Spectra to Aid in Stereochemical Assignments of Molecules with Severe Proton Spectral Overlap
Authors: Powder‐George Yomica , Frank Julia , Ramsewak Russel S. , Reynolds Willam F. 
Published: September 2011

ABSTRACTIntroductionA simple glycoside with only 13 carbons exhibited extensive overlapping of four of the glycosidic protons, causing extreme difficulty in the determination of the stereochemistry of the pyranose unit. However, acquisition of a high‐resolution coupled heteronuclear single‐quantum coherence (HSQC) spectrum overcame this problem. This spectrum provides a useful method for determining vicinal proton coupling constants between strongly coupled protons.ObjectiveTo show the potential of high‐resolution coupled HSQC spectra in overcoming spectral overlap.MethodologyThe sample was obtained by methanol extraction, followed by fractionation and column chromatography of the dried leaves of Montrichardia arborescens (Araceae). NMR spectra were obtained on 1.5 mg of sample dissolved in 120 μL of CD3OD containing 0.1% trimethylsilyl (TMS) as internal standard. A gradient‐selected HSQC spectrum was obtained using standard Varian library pulse sequences in phase sensitive mode. The high‐resolution coupled HSQC spectrum focused on the saccharide region with a 1025 Hz 1H spectral window, a 6300 Hz 13 C spectral window, 1024 data points, a 0.3 Hz relaxation delay, 384 time increments (linear predicted to 4096), and 80 scans per time increment.ResultsThe use of a high‐resolution coupled HSQC spectrum allowed determination of the coupling patterns of the various pyranose protons with sufficient accuracy. This enabled completion of the assignments and identification of the pyranose unit as glucose.ConclusionThe study has shown the effectiveness of the use of a high‐resolution coupled HSQC spectrum in the assignment of molecules with severe spectral overlap. Copyright © 2011 John Wiley & Sons, Ltd.
Synthesis and self‐assembly of amphiphilic macrocyclic block copolymer topologies
Authors: Lonsdale Daria E. , Monteiro Michael J. 
Published: September 2011

AbstractWe demonstrated the synthesis of miktoarm star block copolymers of AB, AB2, and A2B, in which block A consisted of linear poly(tert‐butyl acrylate) (PtBA) and block B consisted of cyclic polystyrene. These structures were produced using the atom transfer radical polymerization to make telechelic polymers that, after modification, were further coupled together by copper‐catalyzed “click” reactions with high coupling efficiency. Deprotection of PtBA to poly(acrylic acid) (PAA) afforded amphiphilic miktoarm structures that when micellized in water gave vesicle morphologies when the block length of PAA was 21 units. Increasing the PAA block length to 46 units produced spherical core‐shell micelles. AB2 miktoarm stars packed more densely into the core compared to its linear counterpart (i.e., a four times greater aggregation number with approximately the same hydrodynamic diameter), resulting in the PAA arms being more compressed in the corona and extending into the water phase beyond its normal Gaussian chain conformation. These results show that the cyclic structure attached to an amphiphilic block has a significant influence on increasing the aggregation number through a greater packing density. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.