bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimal portfolio choice and stochastic volatility
Authors: Gron Anne , Jørgensen Bjørn N. , Polson Nicholas G. 
Published: May 2011

AbstractIn this paper we examine the effect of stochastic volatility on optimal portfolio choice in both partial and general equilibrium settings. In a partial equilibrium setting we derive an analog of the classic Samuelson–Merton optimal portfolio result and define volatility‐adjusted risk aversion as the effective risk aversion of an individual investing in an asset with stochastic volatility. We extend prior research which shows that effective risk aversion is greater with stochastic volatility than without for investors without wealth effects by providing further comparative static results on changes in effective risk aversion due to changes in the distribution of volatility. We demonstrate that effective risk aversion is increasing in the constant absolute risk aversion and the variance of the volatility distribution for investors without wealth effects. We further show that for these investors a first‐order stochastic dominant shift in the volatility distribution does not necessarily increase effective risk aversion, whereas a second‐order stochastic dominant shift in the volatility does increase effective risk aversion. Finally, we examine the effect of stochastic volatility on equilibrium asset prices. We derive an explicit capital asset pricing relationship that illustrates how stochastic volatility alters equilibrium asset prices in a setting with multiple risky assets, where returns have a market factor and asset‐specific random components and multiple investor types. Copyright © 2011 John Wiley & Sons, Ltd.
Nanosized Vanadium, Tungsten and Molybdenum Oxide Clusters Grown in Porous Chitosan Microspheres as Promising Hybrid Materials for Selective Alcohol Oxidation
Authors: El Kadib Abdelkrim , Primo Ana , Molvinger Karine , Bousmina Mosto , Brunel Daniel 
Published: May 2011

AbstractThe ability of chitosan biopolymer to coordinate vanadium, tungsten and molybdenum metallic species and to control their mineralisation growth provides a new family of surface‐reactive organic–inorganic hybrid microspheres. Drying the resulting materials under supercritical conditions allowed the gel network dispersion to be retained, thereby leading to a macroporous catalyst with surface areas ranging from 253 to 278 m2 g−1. On account of the open framework structure of these microspheres, the redox species entangled within the fibrillar network of the polysaccharide aerogels were found to be active, selective and reusable catalysts for cinamylalcohol oxidations.
The Truth about False Unicorn (Chamaelirium luteum): Total Synthesis of 23R,24S‐Chiograsterol B Defines the Structure and Stereochemistry of the Major Saponins from this Medicinal Herb
Authors: Matovic Nicholas J. , Stuthe Julia M. U. , Challinor Victoria L. , Bernhardt Paul V. , Lehmann Reginald P. , Kitching William , De Voss James J. 
Published: May 2011

AbstractChamaelirium luteum is used in traditional medicine systems and commercial botanical dietary supplements for the treatment of female reproductive health problems. Despite the wide use of this herb, only very limited phytochemical characterisation is available. Our investigation of C. luteum roots led to the isolation of two new steroidal saponins 1 and 2 that contain an unusual aglycone 3. The absolute configurations of these molecules were unable to be determined spectroscopically and thus the total synthesis of 3 was undertaken and achieved in 16 steps and 1.6 % overall yield from pregnenolone. The key step in the synthesis was the stereoselective installation of the side chain at C‐17 and C‐20, which employed anion‐accelerated oxy‐Cope methodology. The relative configuration of aglycone 3 was determined by X‐ray crystallography of an advanced synthetic intermediate. The absolute configuration was based upon that of the pregnenolone‐derived steroidal skeleton and determined to be 23R,24S.
Flow of viscous fluids over weirs
Authors: Slocum E. W. 
Published: May 2011

AbstractFlow profiles have been determined experimentally for Newtonian fluids ranging in viscosity from 2,000 to 500,000 cp., flowing over knife‐edged weirs with heights varying from 0.1 to 4.6 in.It has been demonstrated that within the ranges of the variables studied the condition of a flowing system can be defined by specification of four dimensionless groups,

These groups correspond, respectively, to generalized fluid height, distance upstream, flow rate, and viscosity.The results have been fitted by an empirical equation with a standard error of ± 10%.
Spouting of mixed particle‐size beds
Authors: Smith J. W. , Reddy K. V. S. 
Published: May 2011

AbstractA systematic experimental study of the minimum spouting velocity of materials with wide and narrow size ranges, mean particle diameters from 0.0134 to 0.104 inches and solids density from 65.8 to 246.3 lb.m/ft.3has been carried out in a 6‐in. column with four inlet sizes at different bed heights. A new correlation is presented in which the standard deviation of experimental from calculated minimum spouting velocity is 6.87%. Some qualitative conclusions on spoutability, segregation, attrition and electrostatic effects have been presented.
Residence time distribution in multi‐stage systems with recycle
Authors: Haddad A. , Wolf D. , Resnick W. 
Published: May 2011

AbstractEquations are presented for the residence time distribution in multi‐stage systems in which part of the effluent stream is recycled to the inlet of the system. The cases considered include perfect mixing, piston flow and real systems defined by attenuation and time delay factors. Time delay in the recycle stream is also considered. Graphical solutions for several systems are presented. Recycle of part of the effluent stream results in broadening of the residence time distribution and, in addition, produces a discontinuity in the distribution when a time delay is present.
A Multi‐Element Ion‐Pair Extraction for Trace Metals Determination in Environmental Samples
Authors: Saçmacı Şerife , Kartal Şenol 
Published: May 2011

AbstractA multi‐element ion‐pair extraction method was described for the preconcentration of Cd(II), Co(II), Cr(III), Cu(II), Fe(III), Mn(II), Ni(II), Pb(II), and Zn(II) ions in environmental samples prior to their determinations by flame atomic absorption spectrometry (FAAS). As an ion‐pair ligand 2‐(4‐methoxybenzoyl)‐N′‐benzylidene‐3‐(4‐methoxyphenyl)‐3‐oxo‐N‐phenyl‐propono hydrazide (MBMP) was used. Some analytical parameters such as pH of sample solution, amount of MBMP, shaking time, sample volume, and type of counter ion were investigated to establish optimum experimental conditions. No interferences due to major components and some metal ions of the samples were observed. The detection limits of the proposed method were found in the range of 0.33–0.9 µg L−1 for the analyte ions. Recoveries were found to be higher than 95% and the relative standard deviation (RSD) was less than 4%. The accuracy of the procedure was estimated by analyzing the two certified reference materials, LGC6019 river water and RTC‐CRM044 soil. The developed method was applied to several matrices such as water, hair, and food samples.
Selective Separation and Preconcentration of Fe(III) and Zn(II) Ions by Solvent Extraction Using a New Triketone Reagent
Authors: Saçmacı Şerife , Kartal Şenol , Saçmacı Mustafa 
Published: May 2011

AbstractA simple, rapid, and accurate method was developed for separation and preconcentration of trace levels of iron(III) and zinc(II) ions in environmental samples. Methyl‐2‐(4‐methoxy‐benzoyl)‐3‐(4‐methoxyphenyl)‐3‐oxopropanoylcarbamate (MMPC) has been proposed as a new complexing agent for Fe(III) and Zn(II) ions using solvent extraction prior to their determination by flame atomic absorption spectrometry (FAAS). Fe(III) and Zn(II) ions can be selectively separated from Fe(II), Pb(II), Co(II), Cu(II), Mn(II), Cr(III), Ni(II), Cd(II), Ag(I), Au(III), Pd(II), Cr(VI), and Al(III) ions in the solution by using the MMPC reagent. The analytical parameters such as pH, sample volume, shaking time, amount of MMPC reagent, volume of methyl isobutyl ketone (MIBK), effect of ionic strength, and type of back extractant were investigated. The recovery values for Fe(III) and Zn(II) ions were greater than 95% and the detection limits for Fe(III) and Zn(II) ions were 0.26 and 0.32 µg L−1, respectively. The precision of the method as the relative standard deviation changed between 1.8 and 2.1%. Calibration curves have a determination coefficient (r2) of at least 0.997 or higher. The preconcentration factor was found to be 100. Accuracy of the method was checked by analyzing of a certified reference material and spiked samples. The developed method was applied to several matrices such as water, hair, and food samples.
A note on Prandtl boundary layers
Authors: Guo Yan , Nguyen Toan 
Published: May 2011

AbstractThis note concerns nonlinear ill‐posedness of the Prandtl equation and an invalidity of asymptotic boundary layer expansions of incompressible fluid flows near a solid boundary. Our analysis is built upon recent remarkable linear illposedness results established by Gérard‐Varet and Dormy and an analysis by Guo and Tice. We show that the asymptotic boundary layer expansion is not valid for nonmonotonic shear layer flows in Sobolev spaces. We also introduce a notion of weak well‐posedness and prove that the nonlinear Prandtl equation is not well‐posed in this sense near nonstationary and nonmonotonic shear flows. On the other hand, we are able to verify that Oleinik's monotonic solutions are well‐posed. © 2011 Wiley Periodicals, Inc.
eMap and eSlice: a software package for crystallographic computing
Authors: Oleynikov P. 
Published: May 2011

AbstracteMap is an easy‐to‐use suite of computer programs devoted for crystallographic calculations in X‐ray diffraction and electron crystallography. It is used in several key activities: (1) Kinematical structure factors calculation for electrons and X‐rays. (2) Calculation and visualization of 3D electron density/potential maps and peak search in the generated maps. (3) Visualization of reciprocal space in different modes (X‐rays, selected area electron diffraction, Kikuchi lines and bands, electron diffraction precession, etc.). (4) Simulation of HRTEM images and dynamical electron diffraction patterns by multislice method and convergent beam electron diffraction patterns by Bloch‐wave method. (5) Crystal structure refinement from the electron diffraction patterns taking dynamical effects into account. The user‐friendly graphical user interface facilitates the loading or manual data input, and visualization of intermediate and final results in form of 3D graphics or 2D images, plots, and diagrams. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural and morphological studies on Mn substituted ZnO nanometer‐sized crystals
Authors: Mote V. D. , Purushotham Y. , Dole B. N. 
Published: May 2011

AbstractMn substituted ZnO nanocrystals synthesized by a co‐precipitation method. X‐ray diffraction (XRD) studies confirms the presence of wurtzite (hexagonal) crystal structure similar to un doped ZnO, suggesting that doped Mn ions go at the regular Zn sites. The lattice parameters a and c are increasing with increasing Mn content. The unit cell volume increases with increasing Mn concentration, indicating the homogeneous substitution of Mn2+ for the Zn2+. The lattice distortion parameter (εv) is evaluated from XRD data and found that it enhances as Mn content increases. Transmission electron microscopy photographs show that the size of the ZnO crystals is in the range of 20‐50 nm. The SAED pattern confirms the hexagonal and crystalline nature of the samples which are in agreement with X‐ray analysis. The chemical groups of the samples have been identified by FTIR studies (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A critical review of orientation microscopy in SEM and TEM
Authors: Zaefferer S. 
Published: May 2011

AbstractOrientation microscopy (OM) refers to techniques for reconstruction of microstructures based on the spatially resolved measurement of individual crystallographic phases and orientations. This review gives an overview on different techniques of OM in the scanning and transmission electron mi‐croscope. All rely on the automated evaluation of electron diffraction patterns. The most popular technique is based on electron backscatter diffraction (EBSD) in the SEM. In the TEM several techniques are available which are based on either Kikuchi diffraction patterns, spot diffraction patterns with and without electron precession, or reconstructed spot diffraction patterns. Each technique is introduced in detail. Subsequently the techniques are critically compared with respect to their spatial and angular resolution, their robustness in terms of orientation determination and questions of practical applicability for materials science. One point discussed in detail is the spatial resolution. It is shown that the spatial resolution, i.e. the volume from which the diffraction information is generated, is not very different for the SEM and TEM techniques. For this and other reasons we argue that the EBSD technique is in many cases the best suited method for OM. In those cases where it is not (e.g. investigations on truly nanocrystal‐line materials, beam sensitive samples) it is the spot diffraction method combined with electron precession and template matching for orientation determination which offers the best resolution and robustness. The Kikuchi pattern technique in the TEM is only reasonably used when highest angular resolution is to be achieved, e.g. for lattice constant determination. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Self‐template hydrothermal synthesis ZnS microspheres
Authors: Zhang Yidong , Pan Chuncai , Zhang Yange , He Weiwei 
Published: May 2011

AbstractZinc sulfide (ZnS) microspheres were synthesized by a self‐template hydrothermal route using thiourea as sulphur source. The formation of these hollow spheres was mainly attributed to the oriented aggregation of ZnS nanocystals around the gas‐liquid interface between gas (H2S, NH3, or CO2) and water followed by an Ostwald ripening process. The gas bubbles of H2S, NH3, or CO2 produced during the reaction might play a soft‐template to form ZnS hollow microspheres. The products were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), electron diffraction (ED), and photoluminescence (PL). The crystal structure of prepared ZnS microspheres is hexagonal phase polycrystalline. The average microspheres diameter is 1.5 ‐ 6 µm. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Metal Phosphonate Hybrid Mesostructures: Environmentally Friendly Multifunctional Materials for Clean Energy and Other Applications
Authors: Ma Tian‐Yi , Yuan Zhong‐Yong 
Published: May 2011

AbstractThe synthesis of porous hybrid materials has been extended to mesoporous non‐silica‐based organic‐inorganic hybrid materials, in which mesoporous metal phosphonates represent an important family. By using organically bridged polyphosphonic acids as coupling molecules, the homogeneous incorporation of a considerable number of organic functional groups into the metal phosphonate hybrid framework has been realized. Small amounts of organic additives and the pH value of the reaction solution have a large impact on the morphology and textural properties of the resultant hybrid mesoporous metal phosphonate solids. Cationic and nonionic surfactants can be used as templates for the synthesis of ordered mesoporous metal phosphonates. The materials are used as efficient adsorbents for heavy metal ions, CO2, and aldehydes, as well as in the separation of polycyclic aromatic hydrocarbons. They are also useful photocatalysts under UV and simulated solar light irradiation for organic dye degradation. Further functionalization of the synthesized mesoporous hybrids makes them oxidation and acid catalysts, both with impressive performances in the fields of sustainable energy and environment.
Acetylene‐Enhanced Growth of Carbon Nanotubes on Ceramic Microparticles for Multi‐Scale Hybrid Structures
Authors: He Delong , Bai Jinbo 
Published: May 2011

AbstractA mixture of acetylene and xylene is used as the carbon source to directly synthesize carbon nanotube (CNT)/alumina (Al2O3) microsphere hybrid structures by CVD. The hybrid structures are modulated by varying the acetylene ratio and reactor temperature. The addition of acetylene can significantly improve the CNT growth rate on Al2O3 at temperatures lower than 600 °C. A tenfold improvement in CNT growth rate is obtained at 550 °C when only 2 vol.‐% acetylene is added. Meanwhile, acetylene favors the formation of bundles containing high‐density CNTs. The increase in the temperature promotes the formation of CNTs with large diameters and low number density. Mass spectrometry (MS) is used to investigate the decomposition of a mixture of acetylene/xylene at temperatures ranging from 450 to 700 °C, under the experimental conditions used. Acetylene decomposes with an increasing rate with temperature from 450 °C, however notable decomposition of xylene is not detected below 700 °C, which corresponds to the formation of the CNTs of varied diameters. This study demonstrates the possibility of large‐scale production of desired nano/micrometer multifunctional CNT/Al2O3 hybrid fillers using a gas/liquid mixed carbon source.
The Atomic Layer Deposition of SrB2O4 Films Using the Thermally Stable Precursor Bis(tris(pyrazolyl)borate)strontium
Authors: Saly Mark J. , Munnik Frans , Winter Charles H. 
Published: May 2011

AbstractThe atomic layer deposition (ALD) of strontium borate films is carried out using bis(tris(pyrazolyl)borate)strontium (SrTp2) and water as precursors. Self‐limiting ALD growth is established at 350 °C with SrTp2 and water pulse lengths of ≥ 2.0 s and ≥ 0.3 s, respectively. An ALD window is observed from 300 to 375 °C, in which the growth rate is 0.47 Å per cycle. The thin film compositions are assessed by elastic recoil detection analysis (ERDA) and X‐ray photoelectron spectroscopy (XPS). ERDA suggests compositions of SrB2O4 at growth temperatures of < 350 °C, but the boron/strontium and oxygen/strontium ratios are lower than those of SrB2O4 at 350 and 400 °C. Within the ALD window, hydrogen concentrations range from 0.37(42) to 0.87(7) at.‐%, and the carbon and nitrogen concentrations are below the detection limits. XPS analyses on representative strontium borate thin films show all expected ionizations. X‐ray diffraction (XRD) experiments reveal that the as‐deposited films are amorphous. The surface morphology is assessed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The rms surface roughness of typical 2 µm × 2 µm areas for films deposited at 325 and 350 °C are 0.3 and 0.2 nm, respectively. SEM images of these films show no cracks or pinholes.
A new technique for spectrophotometric determination of Pseudoephedrine and Guaifenesin in syrup and synthetic mixture
Authors: Riahi Siavash , Hadiloo Farshad , Milani Seyed Mohammad R. , Davarkhah Nazila , Ganjali Mohammad R. , Norouzi Parviz , Seyfi Payam 
Published: May 2011

AbstractThe accuracy in predicting different chemometric methods was compared when applied on ordinary UV spectra and first order derivative spectra. Principal component regression (PCR) and partial least squares with one dependent variable (PLS1) and two dependent variables (PLS2) were applied on spectral data of pharmaceutical formula containing Pseudoephedrine (PDP) and Guaifenesin (GFN). The ability to derivitize in resolved overlapping spectra chloropheniramine maleate was evaluated when multivariate methods are adopted for analysis of two component mixtures without using any chemical pretreatment. The chemometrics models were tested on an external validation dataset and finally applied to the analysis of pharmaceuticals. Significant advantages were found in analysis of the real samples when the calibration models from derivative spectra were used. It should also be mentioned that the proposed method is a simple and rapid way requiring no preliminary separation steps and can be used easily for the analysis of these compounds, especially in quality control laboratories. Copyright © 2011 John Wiley & Sons, Ltd.
Tgfβ/Alk5 signaling is required for shear stress induced klf2 expression in embryonic endothelial cells
Authors: Egorova Anastasia D. , Van der Heiden Kim , Van de Pas Simone , Vennemann Peter , Poelma Christian , DeRuiter Marco C. , Goumans Marie‐José T. H. , Gittenberger‐de Groot Adriana C. , ten Dijke Peter , Poelmann Robert E. , Hierck Beerend P. 
Published: May 2011

AbstractEndothelial cells (EC) translate biomechanical forces into functional and phenotypic responses that play important roles in cardiac development. Specifically, EC in areas of high shear stress, i.e., in the cardiac outflow tract and atrioventricular canal, are characterized by high expression of Krüppel‐like factor 2 (Klf2) and by transforming growth factor‐beta (Tgfβ)‐driven endothelial‐to‐mesenchymal transition. Extraembryonic venous obstruction (venous clip model) results in congenital heart malformations, and venous clip‐induced alterations in shear stress‐related gene expression are suggestive for an increase in cardiac shear stress. Here, we study the effects of shear stress on Klf2 expression and Tgfβ‐associated signaling in embryonic EC in vivo using the venous clip model and in vitro by subjecting cultured EC to fluid flow. Cellular responses were assessed by analysis of Klf2, Tgfβ ligands, and their downstream signaling targets. Results show that, in embryonic EC, shear stress activates Tgfβ/Alk5 signaling and that induction of Klf2 is an Alk5 dependent process. Developmental Dynamics 240:1670–1680, 2011. © 2011 Wiley‐Liss, Inc.
Asymmetric Synthesis of New β‐Lactam Lipopeptides as Bacterial Signal Peptidase I Inhibitors
Authors: Crauste Céline , Froeyen Matheus , Anné Jozef , Herdewijn Piet 
Published: May 2011

AbstractThe transmembrane bacterial enzyme, signal peptidase I, is recognized as being a promising target for reducing the emergence of drug resistance. The asymmetric synthesis and the biological evaluation of original β‐lactam lipopeptides have been performed to discover potent signal peptidase inhibitors. The importance of the azetidinone motif of these lipopeptides has been demonstrated and can serve as a starting point to exploit and improve the reactivity of the β‐lactam in peptidomimetics.
Minimally invasive endoscopic‐assisted resection of benign tumors in the accessory parotid gland: 5 case studies
Authors: Xie Lei , Zhang Deguang , Lu M. M. Xiaoxiao , Gao B. M. Li 
Published: May 2011

AbstractBackgroundA modified Blair's incision or standard facelift incision is recommended to remove tumors in the accessory parotid gland. These incisions frequently result in long and visible scars. Therefore, the authors have introduced an endoscopic approach via a small preauricular incision to achieve excision of benign tumors in the accessory parotid gland.MethodsThe endoscopic surgical technique was performed on 5 patients with benign tumors in the accessory parotid gland.ResultsEndoscopic‐assisted resection of the benign tumors in the accessory parotid gland was feasible in all 5 patients. This procedure lasted 105 minutes on average. Facial paralysis, salivary fistula, and ear‐lobular numbness were not found postoperatively. The follow‐up period was 1 year, during which no Frey's syndrome and recurrence were found. All preauricular scars were aesthetically satisfactory.ConclusionsThe minimally invasive endoscopic approach via a small preauricular incision is an optional method of the accessory parotid gland benign tumor resection. © 2011 Wiley Periodicals, Inc. Head Neck, 2012