bluuebunny/crossref_metadata_2025_split huggingface dataset:
Response Surface Approach for the Bisorption of Ag(I) by Macrofungus Pleurotus platypus
Authors: Das Devlina , Das Nilanjana 
Published: January 2011

AbstractResponse surface methodology (RSM) employing the three‐level Box–Behnken factorial design was used to optimize the biosorption of Ag(I) by the macrofungus Pleurotus platypus. The initial Ag(I) concentration (100–300 mg/L), pH (3.0–9.0), and biomass dosage (1.0–5.0 g/L) were chosen as the process variables for the optimization. A coefficient of determination (R2) value (0.99), model F value (234.18), and its low p‐value (F < 0.0001) along with the lower value of coefficient of variation (2.44%) indicated the fitness of response surface quadratic model during the present study. At the optimum pH (6.0), initial metal concentration (220 mg/L), and biomass dosage (3.0 g/L), the model predicted 46.7 mg/g Ag(I) uptake and an experimental 46.77 mg/g Ag(I) uptake by P. platypus was obtained. This is the first report on Ag(I) sorption by P. platypus using statistical experimental design employing RSM which may be helpful towards the treatment of industrial effluent containing silver.
Time‐Dependent FRET with Single Enzymes: Domain Motions and Catalysis in H+‐ATP Synthases
Authors: Bienert Roland , Zimmermann Boris , Rombach‐Riegraf Verena , Gräber Peter 
Published: February 2011

AbstractH+‐ATP synthases are molecular machines which couple transmembrane proton transport with ATP synthesis from ADP and inorganic phosphate by a rotational mechanism. Single‐pair fluorescence resonance energy transfer (spFRET) in single molecules is a powerful tool to analyse conformational changes. It is used to investigate subunit movements in H+‐ATP synthases from E. coli (EF0F1) and from spinach chloroplasts (CF0F1) during catalysis. The enzymes are incorporated into liposome membranes, and this allows the generation of a transmembrane pH difference, which is necessary for ATP synthesis. After labelling of appropriate sites on different subunits with fluorescence donor and acceptor, the kinetics of spFRET are measured. Analysis of the EFRET traces reveals rotational movement of the ε and γ subunits in 120° steps with opposite directions during ATP synthesis and ATP hydrolysis. The stepped movement is characterized by a 120° step faster than 1 ms followed by a rest period with an average dwell time of 15 ms, which is in accordance with the turnover time of the enzyme. In addition to the three conformational states during catalysis, also an inactive conformation is found, which is observed after catalysis.
Pd/PdO functionalization of SnO2 nanowires and ZnO nanotetrapods
Authors: De Zorzi C. , Rossetto G. , Calestani D. , Zha M. Z. , Zappettini A. , Lazzarini L. , Villani M. , Habra N. El , Zanotti L. 
Published: February 2011

AbstractTin oxide (SnO2) and zinc oxide (ZnO) nanostructures are widely studied because of their peculiar physical and chemical properties and the large number of possible application fields. Surface functionalization of these materials is a very important topic because it is a powerful tool for modifying or tuning their properties, in order to better match the device requests. For example, palladium/palladium oxide (Pd/PdO) nanoparticles are often used to enhance selectivity of chemoresistive gas sensing properties of metal‐oxide nanostructures. SnO2 nanowires and ZnO nanotetrapods have been grown on large areas by a combination of metal evaporation and controlled oxidation, while a MOCVD (Metal Organic Chemical Vapor Deposition) process has been chosen in order to deposit Pd/PdO nanoparticles on the surface of the obtained oxide nanostructures. Samples morphology, structure and composition have been studied by means of SEM and TEM microscopy, EDS microanalysis and X‐Ray diffraction. The different results, obtained as a function of the synthesis and annealing parameters, are discussed focusing the attention to the experimental conditions that allowed the authors to obtain an optimal “spotted” coverage of oxide nanostructures, which is often required for gas sensing application. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamic modeling of DC–DC converters with peak current control in double‐stage photovoltaic grid‐connected inverters
Authors: Garcerá Gabriel , González‐Medina Raúl , Figueres Emilio , Sandia Jesús 
Published: January 2011

SUMMARYIn photovoltaic (PV) double‐stage grid‐connected inverters a high‐frequency DC–DC isolation and voltage step‐up stage is commonly used between the panel and the grid‐connected inverter. This paper is focused on the modeling and control design of DC–DC converters with Peak Current mode Control (PCC) and an external control loop of the PV panel voltage, which works following a voltage reference provided by a maximum power point tracking (MPPT) algorithm. In the proposed overall control structure the output voltage of the DC–DC converter is regulated by the grid‐connected inverter. Therefore, the inverter may be considered as a constant voltage load for the development of the small‐signal model of the DC–DC converter, whereas the PV panel is considered as a negative resistance. The sensitivity of the control loops to variations of the power extracted from the PV panel and of its voltage is studied.The theoretical analysis is corroborated by frequency response measurements on a 230 W experimental inverter working from a single PV panel. The inverter is based on a Flyback DC–DC converter operating in discontinuous conduction mode (DCM) followed by a PWM full‐bridge single‐phase inverter. The time response of the whole system (DC–DC + inverter) is also shown to validate the concept. Copyright © 2011 John Wiley & Sons, Ltd.
Performance study of mobile WiMAX network with changing scenarios under different modulation and coding
Authors: Bhunia Suman , Misra Iti Saha , Sanyal Salil K. , Kundu Anindita 
Published: January 2011

AbstractWiMAX—the Worldwide Interoperability for Microwave Access is a promising technology for offering high‐speed data, video and multimedia services over mobile platform evolving toward all IP networks. The increasing demand of WiMAX for VoIP and high‐speed multimedia is due to the simplicity of installation and cost reduction compared with the traditional wired DSL cable. The challenges to service providers lie with the Quality of Service (QoS) under varying fading environment while at the same time maximizing for resource utilization. In this paper, a rigorous and comprehensive performance study of mobile WiMAX has been made with respect to adaptive modulation and coding techniques considering the variation in the speed of the mobile, path‐loss, scheduling services and application type for comparing with the fixed type of modulations. The OPNET 14.5.A modeler for WiMAX platform has been used as simulator for adaptation at the physical layer of the transmission in WiMAX OFDMA structure. Observation reveals that dynamic adaptation of modulation and coding schemes based on channel condition enables better QoS while consuming low overall bandwidth of the system. Copyright © 2011 John Wiley & Sons, Ltd.
Polycomb group gene Bmi1 plays a role in the growth of thymic epithelial cells
Authors: Guo Yun , Miyazaki Masaki , Itoi Manami , Satoh Rumi , Iwama Atsushi , Amagai Takashi , Kawamoto Hiroshi , Kanno Masamoto 
Published: January 2011

AbstractPolycomb group gene Bmi1 plays an essential role in HSCs and the BM microenvironment. Recent reports also pointed to the importance of Bmi1 in thymocyte development. However, little is known about its role in the development of the thymic microenvironment. Here, we examined the function of Bmi1 in thymic epithelial cells (TECs) by using the engraftment of fetal thymus (FT) lobes under the kidney capsule. The engrafted Bmi1−/− FT lobes were clearly smaller and the number of thymocytes in these lobes was significantly decreased compared with control FT lobes. Analysis of the cell cycle status of TECs in the reconstituted lobes revealed that the reduction of thymus size in Bmi1−/− FT grafts was caused by less proliferation of TECs during the early expansion stage. Unlike cases with hematopoietic stem cells or thymocytes, the deletion of p16Ink4a and p19Arf could not restore the defects in Bmi1−/− TEC, indicating a distinct role for Bmi1 in TECs. In conclusion, epigenetic regulator polycomb group gene Bmi1 plays a role in the thymic microenvironment in a regeneration process by supporting TEC growth, and thereby contributes to the control of thymus size for T‐cell growth in mice.
XAFS and DFT Characterisation of Protonated Reduced Fe Hydrogenase Analogues and Their Implications for Electrocatalytic Proton Reduction
Authors: Cheah Mun Hon , Best Stephen P. 
Published: February 2011

AbstractThe relationship between the structures of reduced, protonated diiron compounds relevant to the diiron subsite of the Fe‐hydrogenase H cluster, [2Fe]H, and the rate of electrocatalytic proton reduction is explored by a combination of experimental and computational approaches. Analysis of the X‐ray absorption fine structure (XAFS) of the two‐electron, two‐proton product of [Fe(CO)3]2(μ‐PPh2)2 (DP) shows distortions of the primary coordination environment of the Fe centre that result from the trans influence of the terminally bound hydrido ligand. The difference in Fe–C(O) bond lengths for the CO groups cis and trans to the hydrido ligand is similarly predicted by density functional theory, although there is relatively poor agreement between the magnitude of the difference obtained by XAFS and DFT methods. The calculated energies of the cis and trans stereoisomers of DP‐H2 with both hydrido ligands normal to the FeP2 plane (axial:axial) are within 0.5 kcal mol–1 of each other and lower, by approximately 4.5 kcal mol–1, than those of the axial:equatorial isomer. Similar trends in the relative energies are found for the hydrido forms of [Fe(CO)3]2[μ‐PhP(CH2)3PPh] (3P). The rates of dihydrogen elimination from 3P‐H2 and analogues with ethanedithiolate and propanedithiolate bridging ligands (2S‐H2 and 3S‐H2) have been re‐evaluated by using recent DFT calculations of equilibrium constants and reduction potentials. The rate constants 4–8, 2–7 and 1.5–4 s–1 for dihydrogen elimination from the two‐electron, two‐proton analogues of 2S, 3S and 3P, respectively, for reactions conducted with p‐toluenesulfonic acid fall within a narrow range and are consistent with reactions following a similar path but inconsistent with the different transition states proposed for dihydrogen elimination from 2S‐H2 and 3S‐H2.
Oxidovanadium(V) Complexes with Aminoethanol Bis(phenolate) [O,N,O,O′] Ligands: Preparations, Structures, N‐Dealkylation and Condensation Reactions
Authors: Wichmann Oula , Sopo Harri , Lehtonen Ari , Sillanpää Reijo 
Published: February 2011

AbstractThe reactions between [VO(acac)2] (acac– = acetylacetonate ion) or [VO(OPr)3] and trianionic tetradentate N,N‐bis(2‐methylene‐4,6‐alkylphenolate)aminoethanolate ligands, [L13– (4,6‐dimethyl), L23– (4‐methyl, 6‐tert‐butyl), L33– (4‐tert‐butyl, 6‐methyl), L43– (4,6‐di‐tert‐butyl)], afford mononuclear complexes [VO(L1)] (1) and [VO(L2)] (2) with a trigonal bipyramidal coordination sphere around the VV ion, or dinuclear octahedral complexes [V2O2(L3)2] (3) and [V2O2(L4)2] (4). In methanol an adduct with the formula [VO(L1)(MeOH)]·1/2MeOH (5) is obtained. According to multinuclear NMR spectroscopy all those complexes have a mononuclear structure in CDCl3 solutions. In wet polar solvents complex 1 reacts with water and N‐dealkylation occurs producing 3,5‐dimethylsalicyl alcohol, which condensates with 1 and forms a new oxidovanadium complex 6. An ether bond links 3,5‐dimethylsalicyl alcohol to the L13– ligand. To support the reaction mechanism, we have found that in dry acetonitrile 1 reacts directly with salicyl alcohol forming compound 7, which is similar to 6. All compounds 1–7 have been characterized by elemental analysis, multinuclear NMR and X‐ray diffraction.
Total Syntheses of Rhodiolosides A and D and of Sachalinols A–C
Authors: Simon Kristina , Jones Peter G. , Lindel Thomas 
Published: February 2011

AbstractThe glucosylated monoterpenoids (–)‐rhodioloside A and (–)‐rhodioloside D from the roseroot (Rhodiola rosea) have been synthesized for the first time. Glucosylation with tetrapivaloylglucosyl bromide proved superior to the use of tetraacetylglucosyl bromide or glucosyl iodides. Acid‐catalyzed cyclization of a homoglycidol‐type geraniol derivative afforded the monoterpenoid tetrahydrofuran (+)‐sachalinol C from Rhodiola sachalinensis. The absolute configuration of (+)‐sachalinol C requires revision. (–)‐Sachalinol A and (–)‐sachalinol B were also obtained.
In vitro screening of taxol, an anticancer drug produced by the fungus, Colletotrichum capsici
Authors: Kumaran Rangarajulu Senthil , Jung Heehoon , Kim Hyung Joo 
Published: February 2011

AbstractThe fungus Colletotrichum capsici was isolated from the diseased fruits of Chilli plant, Capsicum annuum. The isolated test fungus was identified by its morphological and molecular characteristic features. For the first time, the fungus was screened for the production of taxol on modified liquid medium. The presence of taxol was confirmed by the spectroscopic and chromatographic methods of analyses. The amount of taxol produced by this fungus was quantified by HPLC. The maximum amount of fungal taxol production was recorded as 687 μg/L. The production rate was 13 740‐fold higher than that, previously reported for the fungus Taxomyces andreanae. The extracted fungal taxol showed a strong cytotoxic activity in an in vitro culture of human cancer cells indicating that the increase in taxol concentration induces increased cell death. A PCR‐based screening for taxadiene synthase (ts), a unique gene in the formation of the taxane skeleton, confirmed the molecular blueprint for taxol biosynthesis. The results show that the fungus C. capsici is an excellent candidate for an alternate source of taxol supply and can serve as a potential species for genetic engineering to enhance the production of taxol to a higher level.
Evaluation of three‐dimensional modal pushover analysis for unsymmetric‐plan buildings subjected to two components of ground motion
Authors: Reyes Juan C. , Chopra Anil K. 
Published: February 2011

AbstractThe accuracy of the three‐dimensional modal pushover analysis (MPA) procedure in estimating seismic demands for unsymmetric‐plan buildings due to two horizontal components of ground motion, simultaneously, is evaluated. Eight low‐and medium‐rise structures were considered. Four intended to represent older buildings were designed according to the 1985 Uniform Building Code, whereas four other designs intended to represent newer buildings were based on the 2006 International Building Code. The median seismic demands for these buildings to 39 two‐component ground motions, scaled to two intensity levels, were computed by MPA and nonlinear response history analysis (RHA), and then compared. Even for these ground motions that deform the buildings significantly into the inelastic range, MPA offers sufficient degree of accuracy. It is demonstrated that PMPA, a variant of the MPA procedure, for nonlinear systems is almost as accurate as the well‐known standard response spectrum analysis procedure is for linear systems. Thus, for practical applications, the PMPA procedure offers an attractive alternative to nonlinear RHA, whereby seismic demands can be estimated directly from the (elastic) design spectrum. In contrast, the nonlinear static procedure specified in the ASCE/SEI 41‐06 Standard is demonstrated to grossly underestimate seismic demands for some of the unsymmetric‐plan buildings considered. Copyright © 2011 John Wiley & Sons, Ltd.
Decoding short binary cyclic codes via covering polynomials
Authors: Sung Wonjin , Coffey John T. 
Published: January 2011

AbstractThe paper concerns the covering polynomial method of decoding cyclic codes. This is an easily‐implementable, robust, and low‐complexity decoding algorithm. The determination of the exact complexity of the algorithm is a difficult open problem. In this paper several methods for constructing minimal sets of covering polynomials are proposed for the case R < 2/τ, where τ is the number of errors to be corrected. Complete closed form specifications of the minimal set are given for the case where τ is even, and a computationally efficient procedure presented for general τ is shown to be optimal in many cases (and conjectured to be globally optimal). These results are sufficient to determine the exact minimal number of covering monomials for all binary cyclic codes of length up to 127 with τ < 9. Closed form specifications are available for the covering polynomial set for all such codes.
Complexity/performance tradeoffs in multistage decoders
Authors: Lee Wing‐Man , Kschischang Frank R. 
Published: January 2011

AbstractThis paper describes suboptimal decoding methods for multilevel block‐encoded modulation schemes. These decoding methods can achieve large coding gains with relatively low decoding complexity, and operate, in part, by decoding a supercode of the code to be decoded. By decomposing the multilevel codes in various ways, a wide range of performance/complexity tradeoff points can be obtained. Introducing syndrome checking can further reduce the average decoding complexity with no degradation in performance. Both analysis and extensive simulation results confirm that a given coding gain can be achieved with significantly smaller decoding complexity than Viterbi decoding.
Error and work estimates for high‐order elements
Authors: Löhner Rainald 
Published: January 2011

AbstractError and work estimates for high‐order elements are derived. The comparison of error and work estimates shows that for relative accuracy in the 1% range, which is typical of engineering interest, it may prove very difficult to improve on linear elements. As expected, the estimates also show that the optimal order of element in terms of work and storage demands depends on the desired relative accuracy. Copyright © 2011 John Wiley & Sons, Ltd.
A dual‐weighted trust‐region adaptive POD 4‐D Var applied to a finite‐volume shallow water equations model on the sphere
Authors: Chen X. , Akella S. , Navon I. M. 
Published: January 2011

AbstractIn this paper we study solutions of an inverse problem for a global shallow water model controlling its initial conditions specified from the 40‐yr ECMWF Re‐analysis (ERA‐40) data sets, in the presence of full or incomplete observations being assimilated in a time interval (window of assimilation) with or without background error covariance terms. As an extension of the work by Chen et al. (Int. J. Numer. Meth. Fluids 2009), we attempt to obtain a reduced order model of the above inverse problem, based on proper orthogonal decomposition (POD), referred to as POD 4D‐Var for a finite volume global shallow water equation model based on the Lin–Rood flux‐form semi‐Lagrangian semi‐implicit time integration scheme. Different approaches of POD implementation for the reduced inverse problem are compared, including a dual‐weighted method for snapshot selection coupled with a trust‐region POD adaptivity approach. Numerical results with various observational densities and background error covariance operator are also presented. The POD 4‐D Var model results combined with the trust‐region adaptivity exhibit similarity in terms of various error metrics to the full 4D Var results, but are obtained using a significantly lesser number of minimization iterations and require lesser CPU time. Based on our previous and current work, we conclude that POD 4‐D Var certainly warrants further studies, with promising potential of its extension to operational 3‐D numerical weather prediction models. Copyright © 2011 John Wiley & Sons, Ltd.
A coordinate transformation method for numerical solutions of the electric double layer and electroosmotic flows in a microchannel
Authors: Yao Zhang , Jiankang Wu , Bo Chen 
Published: January 2011

AbstractThe electric double layer (EDL) and electroosmotic flows (EOFs) constitute the theoretical foundations of microfluidics. Numerical solution is one of the effective means of analysis in microfluidics. In general, it is difficult to obtain an accurate numerical solution of complex EOFs because of multiphysical interactions and locally high gradients. In this paper, a new coordinate transformation method is proposed to numerically solve the Poisson–Boltzmann, Navier–Stokes and Nernst–Planck equations to study the EDL and complex EOFs in a microchannel. A series of numerical examples is presented including cases of a homogeneous, discontinous wall electric potential and a locally high wall potential. A systematic comparison of numerical solutions with and without the coordinate transformation is carried out. The numerical results indicate that the coordinate transformation effectively decreases the gradient of the electric potential, ion concentration and electroosmotic velocity in the vicinity of the solid wall, and greatly improves the stability and convergency of the solution. In a transformed coordinate system with a coarse grid, the numerical solutions can be as accurate as those in the original coordinate system with a refined grid. Copyright © 2011 John Wiley & Sons, Ltd.
Prognostic factors in patients with high‐risk locally advanced salivary gland cancers treated with surgery and postoperative radiotherapy
Authors: Feinstein Trevor M. , Lai Stephen Y. , Lenzner Diana , Gooding William , Ferris Robert L. , Grandis Jennifer R. , Myers Eugene N. , Johnson Jonas T. , Heron Dwight E. , Argiris Athanassios 
Published: January 2011

AbstractBackgroundThis study was designed to identify the factors associated with the outcome after standard treatment with surgery and postoperative radiotherapy (RT) for locally advanced salivary gland cancers.MethodsWe conducted a retrospective review of patients with salivary gland cancers registered in the University of Pittsburgh databases from 1990 to 2006.ResultsA total of 74 patients were analyzed. Histologic types included salivary duct carcinoma, 24%; adenoid cystic carcinoma, 23%; and adenocarcinoma, 19%; N2, 39%; N0–1, 58%; and major salivary gland origin, 80%. With a median follow‐up of 4.1 years, the 5‐year recurrence‐free survival (RFS) was 49%, and the 5‐year overall survival (OS) was 55%. The 5‐year local RFS was 76% and the 5‐year distant RFS was 60%. Using Cox‐regression analysis, advanced N classification (N2) was the only significant predictor of both RFS and OS.ConclusionThe long‐term survival of patients with high‐risk, locally advanced salivary gland cancers is unsatisfactory. Advanced nodal disease is strongly associated with patient outcome and should be considered as a stratification factor in future trials in locally advanced salivary gland cancers. © 2011 Wiley Periodicals, Inc. Head Neck, 2011