bluuebunny/crossref_metadata_2025_split huggingface dataset:
Unusual Phase Evolution in MoVTeNb Oxide Catalysts Prepared by a Novel Acrylamide‐Gelation Route
Authors: Kolen'ko Yury V. , Amakawa Kazuhiko , d'Alnoncourt Raoul Naumann , Girgsdies Frank , Weinberg Gisela , Schlögl Robert , Trunschke Annette 
Published: March 2012

AbstractThe phase evolution of MoVTeNb mixed oxides derived from a novel acrylamide‐gelation approach combined with subsequent washing by hydrogen peroxide and/or annealing in argon was investigated by using powder X‐ray diffraction and scanning electron microscopy in conjunction with energy‐dispersive X‐ray spectroscopy. The calcination of acrylamide‐gelation derived carbon‐based xerogels in air at 410 °C afforded at unexpected low temperature the formation of a phase mixture containing a significant amount of small MoVTeNb oxide crystallites consisting of the M1 phase (ICSD no. 55097). Hydrogen peroxide treatment drastically changed the phase evolution upon annealing in argon at 600 °C. Whereas further enrichment of the M1 phase took place for the untreated precursor, annealing of the washed material resulted in complete collapse of the M1 phase, yielding a ternary MoVNb mixed oxide with tetragonal Mo5O14‐type structure (ICSD no. 27202). The reducing effect of organic residues on phase evolution during calcination of the carbon‐inorganic xerogel in air is discussed. The presence of side phases and the deficiency in tellurium upon annealing have a critical impact on the phase composition of the final product. The catalysts exhibit significant activity in partial oxidation of propane to acrylic acid. The analysis of the product distribution suggested that the activation of both propane and propylene intermediates proceed exclusively over the M1 phase, while side phases do not play a significant role in the reaction.
Molecularly Imprinted Shells from Polymer and Xerogel Matrices on Polystyrene Colloidal Spheres
Authors: Guan Guijian , Liu Renyong , Mei Qingsong , Zhang Zhongping 
Published: March 2012

AbstractWe have devised a facile and general methodology for the synthesis of various molecularly imprinted shells at the surface of polystyrene (PS) colloidal spheres to recognize the explosive compound 2,4,6‐trinitrotoluene (TNT). PS spheres with surface‐functionalized carboxyl‐group layers could direct a selective imprinting polymerization on their surface through the hydrogen‐bonding interactions between surface carboxyl groups and amino monomers. Meanwhile, homogeneous polymerization in the solution phase was completely prevented by stepwise polymerization. The overall process led to the formation of monodisperse molecularly imprinted core–shell microspheres, and was very successful in the preparation of organic polymer and inorganic xerogel shells. Furthermore, greater capacity and faster binding kinetics towards target species were achieved, because surface‐imprinted sites ensured the complete removal of templates, good accessibility to target molecules, and low mass‐transfer resistance. The results reported herein, concerning the production of high‐quality molecularly imprinted products, could also form the basis for the formulation of a new strategy for the fabrication of various functional coating layers on colloidal spheres with potential applications in the fields of separations and chemical sensing.
On the Role of Hydrogen Bonds in Photoinduced Electron‐Transfer Dynamics between 9‐Fluorenone and Amine Solvents
Authors: Ghosh Hirendra N. , Adamczyk Katrin , Verma Sandeep , Dreyer Jens , Nibbering Erik T. J. 
Published: March 2012

AbstractUsing ultrafast fluorescence upconversion and mid‐infrared spectroscopy, we explore the role of hydrogen bonds in the photoinduced electron transfer (ET) between 9‐fluorenone (FLU) and the solvents trimethylamine (TEA) and dimethylamine (DEA). FLU shows hydrogen‐bond dynamics in the methanol solvent upon photoexcitation, and similar effects may be anticipated when using DEA, whereas no hydrogen bonds can occur in TEA. Photoexcitation of the electron‐acceptor dye molecule FLU with a 400 nm pump pulse induces ultrafast ET from the amine solvents, which is followed by 100 fs IR probe pulses as well as fluorescence upconversion, monitoring the time evolution of marker bands of the FLU S1 state and the FLU radical anion, and an overtone band of the amine solvent, marking the transient generation of the amine radical cation. A comparison of the experimentally determined forward charge‐separation and backward charge‐recombination rates for the FLU‐TEA and FLU‐DEA reaction systems with the driving‐force dependencies calculated for the forward and backward ET rates reveals that additional degrees of freedom determine the ET reaction dynamics for the FLU‐DEA system. We suggest that hydrogen bonding between the DEA molecules plays a key role in this behaviour.
An Improved Route to (+)‐Tedanolide and Analysis of Its Subtle Effects Controlling Conformation and Biological Behaviour
Authors: Diaz Nina , Zhu Mingzhao , Ehrlich Gunnar , Eggert Ulrike , Muthukumar Yazh , Sasse Florenz , Kalesse Markus 
Published: March 2012

AbstractThe improved synthesis of the antitumor compound (+)‐tedanolide is described through an aldol coupling of bis‐ketone 7. This modification shortens the synthetic steps in the endgame and provides rapid access to this biologically important natural product. Additionally, it serves as a probe in order to unravel the conformational effects that impede or enable its successful synthesis. Having this way access to des‐epoxy‐tedanolide, its biological characterization surprisingly unravelled the mode of action to resemble candidaspongiolide rather than deoxytedanolide.
A Way to Stable, Highly Emissive Fluorubine Dyes: Tuning the Electronic Properties of Azaderivatives of Pentacene by Introducing Substituted Pyrazines
Authors: Fleischhauer Jan , Zahn Stefan , Beckert Rainer , Grummt Ulrich‐Walter , Birckner Eckhard , Görls Helmar 
Published: March 2012

AbstractPentacene and its derivatives are among the most important examples of π‐electron‐rich molecules used in organic field effect transistors. The replacement of CH groups by nitrogen atoms opens an elegant way to generate highly electron‐deficient molecules, known as oligoazaacenes. We describe the synthesis and spectroscopic properties of two novel derivatives of this family, namely the zwitterionic and quinoidal conjugated forms of dihydro‐5,6,7,12,13,14‐hexaazapentacene (fluorubine). We outline a powerful strategy to tune the electronic properties of these redox‐active azaacenes by the selective introduction of substituted pyrazines. Their acidochromic and solvatochromic behaviour is investigated experimentally and interpreted with the help of theoretical calculations. The simple “exchange” of substituents or protonation is shown to significantly alter the spectroscopic and electronic properties of these remarkably stable π‐systems. Their exceptional optical properties, such as high fluorescence quantum yields combined with a redox‐active behaviour, make them promising candidates for sensor materials. Additional marked features in the solid state, such as herringbone packing in combination with short π–π distances, will open access to electronic materials.
Noninvasive Diagnostic Techniques for Coronary Disease in Women
Authors: Vavas Eleni , Hong Susie N. , Rosen Stacey E. , Mieres Jennifer H. 
Published: March 2012

AbstractSignificant advances in medical treatment, medical technology, and the focus on sex‐specific research have contributed to a reduction in cardiovascular mortality in women. Despite these advances, coronary artery disease (CAD) is the leading cause of cardiovascular death of women in the Western world. In the past 2 decades, the focused research on women at risk for CAD has helped to clarify our understanding of some of the sex‐specific factors that are important in the detection of CAD. In women, the detection and evaluation of physiologically significant CAD can be challenging. Many of the traditional tests that are designed to detect focal areas of coronary artery stenosis are less sensitive and specific in female patients, who have a greater burden of symptoms, higher atherosclerotic burden, and lower prevalence of obstructive coronary disease. In this article, we review the available evidence on the role of contemporary noninvasive diagnostic techniques in the evaluation of women with symptoms of CAD.The authors have no funding, financial relationships, or conflicts of interest to disclose.
Heart Failure in Women
Authors: Shin J. Julia , Hamad Eman , Murthy Sandhya , Piña Ileana L. 
Published: March 2012

AbstractHeart failure (HF) has steadily increased in prevalence and affects both males and females equally. Despite this, there has been a significant underrepresentation of women in large scale HF trials. This disparity has lead to a deficit in understanding important gender‐based differences in pathophysiology, diagnosis and treatment strategies.We review these gaps and explore a biological basis for varying outcomes. Endogenous estrogen plays an important role in epidemiology and outcome. The administration of exogenous estrogen has had varied success in treatment and is outlined extensively below. Additionally, we highlight unique HF syndromes through pregnancy and important sex‐specific issues concerning transplant and mechanical circulatory support. A central theme remains: there is a clear need for increased female recruitment in clinical trials, and more studies exploring the role of gender‐based biology in HF treatment. © 2012 Wiley Periodicals, Inc.The authors have no funding, financial relationships, or conflicts of interest to disclose.
Arrhythmias in Women
Authors: Curtis Anne B. , Narasimha Deepika 
Published: March 2012

AbstractThere are important gender differences in cardiac electrophysiology that affect the epidemiology, presentation, and prognosis of various arrhythmias. Women have been noted to have higher resting heart rates compared to men. They also have a longer QT interval, which puts them at an increased risk for drug‐induced torsades de pointes. Women with atrial fibrillation are at a higher risk of stroke, and they are less likely to receive anticoagulation and ablation procedures compared to men. Women have a lower risk of sudden cardiac death and are less likely to have known coronary artery disease at the time of an event compared to men. Both men and women have been shown to derive an equal survival benefit from implantable cardioverter defibrillators and cardiac resynchronization therapy, although these devices are significantly underutilized in women. Women also appear to have a better response to cardiac resynchronization therapy in terms of reduced numbers of hospitalizations and more robust reverse ventricular remodeling. Further studies are required to elucidate the underlying pathophysiology of these sex differences in cardiac arrhythmias. © 2012 Wiley Periodicals, Inc.The authors have no funding, financial relationships, or conflicts of interest to disclose.
Hidden Markov Analysis of Trajectories in Single‐Molecule Experiments and the Effects of Missed Events
Authors: Stigler Johannes , Rief Matthias 
Published: March 2012

AbstractThe ever more complex fluctuation patterns discovered by single molecule experiments require statistical methods to analyze multi‐state hopping traces of long lengths. Hidden Markov modeling is a statistical tool that offers the scalability to analyze even complex data and extract kinetic information. We give an introduction on how to implement hidden Markov modeling for the analysis of single molecule force spectroscopic traces, deal with missed events, and test the method on a calcium binding protein.
The Beryllium Pentamer: Trailing an Uneven Sequence of Dissociation Energies
Authors: Ascik Peter N. , Rugango René , Simmonett Andrew C. , Compaan Katherine R. , Schaefer Henry F. 
Published: March 2012

AbstractRecent high‐resolution spectroscopic studies by Merritt, Bondybey, and Heaven (Science 2009, 324, 1548) have heightened the anticipation that small beryllium clusters will soon be observed in the laboratory. Beryllium clusters are important discrete models for the theoretical study of metals. The trigonal bipyramidal Be5 molecule is studied using high‐level coupled cluster methods. We obtain the optimized geometry, atomization and dissociation energies, and vibrational frequencies. The c∼CCSDT(Q) method is employed to compute the atomization and dissociation energies. In this approach, complete basis set (CBS) extrapolations at the CCSD(T) level of theory are combined with an additive correction for the effect of iterative triple and perturbative quadruple excitations. Harmonic vibrational frequencies are obtained using analytic gradients computed at the CCSD(T) level of theory. We report an atomization energy of 129.6 kcal mol−1 at the trigonal bipyramid global minimum geometry. The Be5→Be4+Be dissociation energy is predicted to be 39.5 kcal mol−1. The analogous dissociation energies for the smaller beryllium clusters are 64.0 kcal mol−1 (Be4→Be3+Be), 24.2 kcal mol−1 (Be3→Be2+Be), and 2.7 kcal mol−1 (Be2→Be+Be). The trigonal bipyramidal Be5 structure has an equatorial–equatorial bond length of 2.000 Å and an axial–equatorial distance of 2.060 Å. Harmonic frequencies of 730, 611, 456, 583, 488, and 338 cm−1 are obtained at the CCSD(T)/cc‐pCVQZ level of theory. Quadruple excitations are found to make noticeable contributions to the energetics of the pentamer, which exhibits a significant level of static correlation.
Control of Heteroepitaxial Growth of CaCu3Ti4O12 Films on SrTiO3 Substrates by MOCVD
Authors: Catalano Maria Rita , Malandrino Graziella , Toro Roberta G. , Lo Nigro Raffaella 
Published: March 2012

AbstractThin films of CaCu3Ti4O12 (CCTO) are successfully deposited by metal‐organic (MO)CVD on (001)SrTiO3 substrates. An interesting approach, based on a molten multi‐component precursor source, is applied. The molten mixture consists of the Ca(hfa)2•tetraglyme, Ti(tmhd)2(OiPr)2, and Cu(tmhd)2 [Hhfa = 1,1,1,5,5,5‐hexafluoro‐2,4‐pentanedione; tetraglyme = 2,5,8,11,14‐pentaoxapentadecane; Htmhd = 2,2,6,6‐tetramethyl‐3,5‐heptandione; OiPr = iso‐propoxide] precursors. It is also found that, in the present case of a relatively large lattice mismatch (∼5%), the epitaxial growth can be achieved by a careful optimization of deposition parameters. Film structural and morphological characterization is carried out using several techniques; X‐ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). A complete comparison between films deposited by two main processes is carried out in order to understand the kinetic and thermodynamic issues involved in the MOCVD epitaxial growth.
Dynamic channel selection with reinforcement learning for cognitive WLAN over fiber
Authors: Li Yi , Ji Hong , Li Xi , Leung Victor C.M. 
Published: March 2012

SUMMARYThe Internet of Things (IoT) is the next big possibility and challenge for the future information networks. It makes the interaction between people and things more active and provides the connection among different existing networks. Ubiquitous short‐range wireless access and cognitive radio are key technologies for the IoT's realization. This paper deals with some problems in an integrated system of wireless local area network (WLAN) and cognitive radio — cognitive WLAN over fiber (CWLANoF). CWLANoF is a cost‐effective and efficient architecture that combines radio over fiber and cognitive radio technologies to provide centralized radio resource management and equal spectrum access in infrastructure‐based IEEE 802.11 WLANs. In this paper, a reinforcement learning approach is applied to implement dynamic channel selection in CWLANoF. The cognitive access points select the best channels among the industrial, scientific, and medical band for data packet transmission, given that the objective is to minimize external interference and acquire better network‐wide performance. The reinforcement learning method avoids solving complex optimization problems while being able to explore the states of a CWLANoF system during normal operations. Simulation results reveal that the proposed strategy is effective in avoiding aggregated interference, reducing outage probability, and improving network throughput. Copyright © 2012 John Wiley & Sons, Ltd.
Allopurinol attenuates left ventricular dysfunction in rats with early stages of streptozotocin‐induced diabetes
Authors: Gao Xia , Xu Yuan , Xu Bo , Liu Yanan , Cai Jun , Liu Hui‐min , Lei Shaoqing , Zhong Yin‐qin , Irwin Michael G. , Xia Zhengyuan 
Published: March 2012

AbstractBackgroundXanthine oxidase‐derived superoxide production and oxidative stress contribute to the development of diabetic complications including diabetic cardiomyopathy. We hypothesized that xanthine oxidase‐inhibitor allopurinol (ALP) may decrease hyperglycemia‐induced oxidative stress, ameliorate cardiomyocyte hypertrophy and fibrosis, and attenuate the development of left ventricle (LV) diastolic dysfunction in rats with streptozotocin (STZ)‐induced diabetes.MethodsControl Sprague Dawley (C) or streptozotocin‐induced diabetic (D) rats were either untreated or treated with allopurinol (100 mg/kg/day) for 4 weeks starting at 1 week after streptozotocin injection. Free 15‐F2t‐isoprostane, a specific indicator of oxidative stress was measured by enzymatic immunoassay. The cardiomyocyte cross‐sectional area was assessed by hematoxylin and eosin‐stained paraffin‐embedded sections of LVs. Myocardial collagens I and III were assessed by immunol histochemistry and Western blotting. Echocardiography was performed to characterize cardiac structure and function.ResultsIn diabetic rats, both plasma and cardiac tissue levels of free 15‐F2t‐isoprostane were increased (p < 0.05 vs. control), accompanied with significant increase (p < 0.05 vs. control) in cross‐section area and myocardial collagen deposition of LV cardiomyocyte. Echocardiography in diabetic rats showed that LV weight/body weight ratio was significantly higher than in control rats, whereas the levels of LV end‐diastolic volume and stroke volume were decreased (all p < 0.05 diabetic vs. control). All these changes were either attenuated or prevented by allopurinol. In addition, LV ejection fraction in diabetic rats treated with allopurinol was higher than that in untreated diabetic rats (p < 0.05).ConclusionAllopurinol can attenuate hyperglycemia‐induced oxidative stress, ameliorate cardiomyocyte hypertrophy and fibrosis and subsequently prevent left ventricular dysfunction in early diabetes. Copyright © 2012 John Wiley & Sons, Ltd.
Major antioxidant constituents from Satureja hortensis L. extracts obtained with different solvents
Authors: Plánder Szabina , Gontaru Lenuta , Blazics Balázs , Veres Katalin , Kéry Ágnes , Kareth Sabine , Simándi Béla 
Published: March 2012

AbstractAnalysis of different extracts of Satureja hortensis L. obtained with various solvents (by supercritical CO2 and by traditional extraction techniques) is presented in this study to identify and to determine the major constituents responsible for the antioxidant activity. The total polyphenol and total flavonoid contents of the extracts were determined by spectrophotometric method and no correlation was found with the antioxidant activites. HPLC was also used to measure two diterpenes as carnosol and carnosic acid in the extracts. Neither carnosol nor carnosic acid were identified. Individual antioxidants as rosmarinic and caffeic acids were identified and quantified with TLC‐densitometry method. Rosmarinic acid was found in higher amount than caffeic acid. The content of rosmarinic acid was also determined with HPLC. A good correlation coefficient of 0.85 was found between the antioxidant activity and amount of rosmarinic acid, which leads to the conclusion that rosmarinic acid is among the main antioxidant compounds of S. hortensis L. plant.
Generation of Stereocenters Around a C3‐Symmetric Cyclotriveratrylene Crown
Authors: Sansévérino Julien , Aubert Emmanuel , Espinosa Enrique , Chambron Jean‐Claude 
Published: March 2012

AbstractThe oxidation of racemic methylthio‐substituted C3‐symmetric cyclotriveratrylene (CTV) 2 produces the corresponding trisulfoxides 3 as follows. Oxidation with m‐chloroperoxybenzoic acid (m‐CPBA) in dichloromethane leads to the formation of a distribution of the four possible diastereomers that is relatively close to the statistical outcome, in which the C3‐symmetric stereoisomers are the minor species. In contrast, the optically active Davis reagent [oxaziridine (+)‐4] in carbon tetrachloride at room temperature leads to a biased (73 %) distribution in favor of the C3‐symmetric MRRR/PSSS diastereomer of 3 with 56 % ee (PSSS enantiomer according to the model of Davis). Interestingly, when the oxidation is carried out in toluene at reflux, the distribution is switched to approximately equal amounts of the C3‐symmetric MSSS/PRRR and asymmetric MRSS/PSRR diastereomers of 3. Overall, however, these results point to the negligible role played by the chirality of the CTV platform on the induction of chirality at the sulfur prochiral centers.
In ovo exposure to nonylphenol and bisphenol A resulted in dose-independent feminization of male gonads in Japanese quail (Coturnix japonica) embryos
Authors: Oshima Atsushi , Yamashita Ryo , Nakamura Keigo , Wada Masaru , Shibuya Kazumoto 
Published: March 2012

Abstract
Sex reversal effects of nonylphenol and bisphenol A on the gonads in F1(AWE × WE) Japanese quail (Coturnix japonica) embryos were investigated using an in vivo screening model developed previously. The F1 (AWE × WE) Japanese quail are a useful avian model because sex differentiation is confirmed by the plumage color before hatching, ruled by a criss-cross inheritance. The nonylphenol at 200, 2,000, 20,000, and 200,000 ng/egg and bisphenol A at 20, 200, 2,000, and 20,000 ng/egg were injected into the egg white just before incubation. At 16 d of incubation, embryos were subjected to a complete necropsy, and their gonads were both grossly observed and examined histopathologically and morphometrically. Grossly, genetic sex was confirmed because plumage color coincided completely with the external sex phenotype of the gonads in all embryos. Histopathologically, feminization of the male gonad, called ovotestis, developed in the left testis in all nonylphenol- and bisphenol A-treated groups. The incidence of the lesion in all treated groups was significantly higher than that in the control group, whereas there were no dose-dependent changes in the incidence and area of the ovotestis in both nonylphenol- and bisphenol A-treated groups. The present study revealed that nonylphenol and bisphenol A have a dose-independent potential of ovotestis induction in the Japanese quail embryo. Environ. Toxicol. Chem. 2012; 31: 1091–1097. © 2012 SETAC