bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nonisothermal modeling of heat transfer inside an internal batch mixer
Authors: Bai Yun , Sundararaj Uttandaraman , Nandakumar Krishnaswamy 
Published: November 2010

AbstractA nonisothermal transient process of temperature increase due to viscous heating was simulated for a 69 cm3 internal batch mixer (BM) using a computational fluid dynamics (CFD) software, Polyflow 3.9 form ANSYS, Inc., to obtain the temporal temperature distribution and characterize the heat transfer between polymer melt and mixer wall. The melt temperature obtained from simulation was verified with experiments. Starting from a uniform temperature of 463 K, when a rotation speed of 5.24 rad/s is imposed, viscous heating caused a maximum temperature rise of 3 K for a polyethylene (PE) resin, and 6 K for a polystyrene (PS) resin. The transient flow fields inside the batch mixer were characterized with velocity profiles and a mixing index parameter, which show that laminar flow dominates inside the mixer while a small percentage of elongational flow, converging flow, and recirculation flow is also present. © 2010 American Institute of Chemical Engineers AIChE J, 2011
Optimal design of nonlinear temperature programmed reduction experiments
Authors: Heidebrecht Peter , Sundmacher Kai , Biegler Lorenz T. 
Published: November 2010

AbstractWe propose the application of nonconstant temperature gradients to improve the quality of temperature programmed reduction (TPR) experiments with respect to parameter estimation and model discrimination. This leads to TPR experiments with nonlinear temperature profiles (N‐TPR). To determine optimal profiles for the temperature gradient, optimal control problems are set up and solved numerically. The results show that N‐TPR experiments can be significantly better than traditional linear TPR experiments for many different scenarios. To implement these results in practice, we develop and demonstrate reduced optimization problem formulations, which can be solved faster and more reliably than the original formulation, with very similar results. © 2011 American Institute of Chemical Engineers AIChE J, 2011
Verification of filtered two‐fluid models for gas‐particle flows in risers
Authors: Igci Yesim , Sundaresan Sankaran 
Published: November 2010

AbstractThe effect of solid boundaries on the closure relationships for filtered two‐fluid models for riser flows was probed by filtering the results obtained through highly resolved kinetic theory‐based two‐fluid model simulations. The closures for the filtered drag coefficient and particle phase stress depended not only on particle volume fraction and the filter length but also on the distance from the wall. The wall corrections to the filtered closures are nearly independent of the filter length and particle volume fraction. Simulations of filtered model equations yielded grid length independent solutions when the grid length is ∼half the filter length or smaller. Coarse statistical results obtained by solving the filtered models with different filter lengths were the same and corresponded to those from highly resolved simulations of the kinetic theory model, which was used to construct the filtered models, thus verifying the fidelity of the filtered modeling approach. © 2010 American Institute of Chemical Engineers AIChE J, 2011
Characterization of solvent‐spun polyester nanofibers
Authors: Duzyer S. , Hockenberger A. , Zussman E. 
Published: November 2010

AbstractThe aim of this study was to examine the properties of polyester nanofibers produced by the electrospinning method. Solvent‐spun nanofibers with different concentrations of poly(ethylene terephthalate) (13, 16, and 20 wt %) were produced. The morphology and surface energy of the fibers were analyzed by scanning electron microscopy and contact angle measurements. Tensile testing, dynamic mechanical analysis, and differential scanning calorimetry were carried out to characterize the thermal and mechanical properties. X‐ray diffraction and attenuated total reflection Fourier transform infrared spectroscopy tests were performed to analyze the microstructural properties. The results show that a nanoweb of the 16 wt % solution had better mechanical and thermal behaviors because of the increased molecular orientation in the amorphous structure and the narrower fiber diameter distribution in the web. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
The Variety of Microalgae Applications as a Renewable Resource
Authors: Rosello Sastre R. , Posten C. 
Published: November 2010

AbstractDie biotechnologische Nutzung von Mikroalgen hat in den letzten Jahrzenten erheblich an Bedeutung gewonnen. Mikroalgen werden als eine der vielversprechendsten Quellen neuer Produkte und Anwendungen angesehen. Ziel dieses Beitrags ist es, eine Übersicht über den aktuellen technischen und kommerziellen Stand der Gewinnung von Produkten aus Mikroalgen zu geben. Während Anwendungen im Bereich von Kosmetik und Lebensmittelergänzung seit langem Standard sind, werden neue Massenprodukte für Futter‐ und Lebensmittel, Feinchemikalien und Biokraftstoffe intensiv erforscht. Zur Bedienung der sich abzeichnenden Märkte dieser Mittel‐ und Niedrigpreis‐ Produkte besteht allerdings noch Entwicklungsbedarf für die verbesserte Wirtschaftlichkeit der Mikroalgen‐Biotechnologie.
Density Functional Theory Study of Hydrogen Bonding Dimers with 4‐Pyridinecarboxylic Acid Hydrazine
Authors: Yang Qiongfen , Xie Bingyun , Li Quan , Zhao Keqing 
Published: November 2010

AbstractThe H‐bonding dimers of 4‐pyridinecarboxylic acid hydrazine were studied using density functional theory (DFT) at B3LYP/6‐311++G** level. The results showed that the most stable dimer D1 had two same linear NH···O hydrogen bonds, and the interaction energy between them was 51.038 kJ·mol−1 which was corrected by the basis set superposition error and zero‐point. The stretching vibration frequency of NH bond had a red shift because of the hydrogen bonds. The natural bond orbital analysis showed that each NH···O hydrogen bond in D1 had the biggest interaction stabilization energy of 69.078 kJ·mol−1. Thermodynamic analysis indicated that the formation process of D1 was exothermic and spontaneous at low and room temperatures.
Characterization and Analysis of the Electrochemical Properties of the Polyaniline Synthesized by Emulsion Polymerization in Constant Magnetic Field (0.4 T)
Authors: Ma Li , Luo Laizheng , Ma Haotian , Li Xiaofeng , Su Wenyi , Hao Shaona 
Published: November 2010

AbstractA new, convenient and economical method was established firstly, which took loaded polyaniline (PANI) carbon paper as the working electrode to real‐time characterize and analyze the electrochemical properties of the PANI synthesized by emulsion polymerization in constant magnetic field (MF, 0.4 T). The characterization results of the electrochemical properties of the PANI had been proved by contrast analysis of the thermal stability of conductivity, FT‐IR, XRD and TGA of the PANI. The experimental results of cyclic voltammogram, AC impedance, Tafel curve and electrochemical stability showed that the PANI synthesized in the presence of the MF had larger redox current, smaller charge resistance, higher corrosion potential and better electrochemical stability. The PANI thermal stability of conductivity had been measured in the temperature range from 20 to 140°C, and the results showed that the PANI synthesized in the presence of the MF had better thermal stability of conductivity. The results of FT‐IR, XRD and TGA indicated that the characteristic peaks of FT‐IR spectra of the PANI synthesized in the presence of the MF shifted to the lower wavenumbers, and its crystallinity and thermal stability were also improved.
Direct Electrochemistry and Electrocatalysis Behaviors of Glucose Oxidase Based on Hyaluronic Acid‐Carbon Nanotubes‐Ionic Liquid Composite Film
Authors: Shangguan Xiaodong , Zheng Jianbin , Zhang Hongfang , Tang Hongsheng 
Published: November 2010

AbstractMulti‐walled carbon nanotubes (MWNTs) were dispersed in the ionic liquid [BMIM][BF4] to form a uniform black suspension. Based on it, a novel glucose oxidase (GOx)‐hyaluronic (HA)‐[BMIM][BF4]‐MWNTs/GCE modified electrode was fabricated. UV‐vis spectroscopy confirmed that GOx immobilized in the composite film retained its native structure. The experimental results of EIS indicated MWNTs, [BMIM][BF4] and HA were successfully immobilized on the surface of GCE and [BMIM][BF4]‐MWNTs could obviously improve the diffusion of ferricyanide toward the electrode surface. The experimental results of CV showed that a pair of well‐defined and quasi‐reversible peaks of GOx at the modified electrode was exhibited, and the redox reaction of GOx at the modified electrode was surface‐confined and quasi‐reversible electrochemical process. The average surface coverage of GOx and the apparent Michaelis‐Menten constant were 8.5×10−9 mol/cm2 and 9.8 mmol/L, respectively. The cathodic peak current of GOx and the glucose concentration showed linear relationship in the range from 0.1 to 2.0 mmol/L with a detection limit of 0.03 mmol/L (S/N=3). As a result, the method presented here could be easily extended to immobilize and obtain the direct electrochemistry of other redox enzymes or proteins.
Theoretical Studies on the Electronic Structures and Optical Properties of Tri‐aryl End‐capped Terthiophene Derivatives
Authors: Wei Ni , Wang Wenliang , Yin Shiwei , Du Song , Wang Weina 
Published: November 2010

AbstractThe relationships between electronic structures and spectra properties are investigated by DFT/TDDFT for terthiophene derivatives, BMA‐3T (tri‐aryl amine end‐capped terthiophene), BBA‐3T (tri‐aryl amine and tri‐aryl boron end‐capped terthiophene) and BPB‐3T (tri‐aryl boron end‐capped terthiophene). The calculated results show that BMA‐3T, BBA‐3T and BPB‐3T have higher HOMO energy level and lower ionization potentials (IPs) than 3T. BMA‐3T has good hole injection ability and hole‐transport property as reported in experiment. The designed molecule of BBA‐3T and BPB‐3T own lower LUMO level and higher electron affinities (EAs) than BMA‐3T, which facilitate electron injection and improve their electron‐transport properties. Surprisingly, BPB‐3T has preferable charge equilibrium property since its hole reorganization energy (λh) is close to electron reorganization energy (λe). The ΔE (HOMO−LUMO) and Eg of these three derivatives are narrower compared to 3T, and the absorption as well as emission spectrum exhibited red‐shifts.
The Modifiable Character of a Novel Ru‐Fe‐B/ZrO2 Catalyst for Benzene Selective Hydrogenation to Cyclohexene
Authors: Liu Zhongyi , Sun Haijie , Wang Dongbin , Liu Shouchang , Li Zhongjun 
Published: November 2010

AbstractA novel Ru‐Fe‐B/ZrO2 catalyst for the selective hydrogenation of benzene to cyclohexene was prepared by the chemical reduction method. A yield of cyclohexene of 57.3% was achieved at benzene conversion of 80.6% on this catalyst. The activity and yield of cyclohexene were higher than those studied previously. The structural characterizations of the catalyst were performed by TEM‐SAED, XRD, and N2‐physisorption. Moreover, cyclohexene selectivities on this catalyst increased and the activities decreased with the increase of the ZnO dosages, however, the activities increased and cyclohexene selectivities decreased with the increase of the H2SO4 dosages. Different feeding manners of H2SO4 or ZnO exerted definitely influence on the performances of this catalyst, but the degrees of influence were different due to the character of chemisorptions. Furthermore, the activity and cyclohexene selectivity on the catalysts could be reversibly modified by adding H2SO4 or ZnO into reaction slurry, which provides an easy method to recover the activity and selectivity of Ru‐Fe‐B/ZrO2 catalysts during the process of producing cyclohexene. And the modifiable mechanisms involved were speculated.
Hydrogen Bonded Supramolecular Liquid Crystalline Complex of 2,4,6‐Triarylamino‐1,3,5‐triazines with Semiperfluorinated Benzoic Acids
Authors: Cheng Xiaohong , Jin Jie , Li Quan , Dong Xing 
Published: November 2010

AbstractHydrogen bonded supramolecular complexes of 2,4,6‐triarylamino‐1,3,5‐triazines (Tn) with semiperfluorinated benzoic acids have been prepared. The mesophase behaviors of such complexes were investigated with POM (polarized optical microscopy), DSC (differential scanning calorimetry) and X‐ray diffraction. Columnar mesophase was found in the equimolar mixtures of the triazines with the semiperfluorinated benzoic acids. While the equimolar mixture of triazines with the nonfluorinated three fold alkoxy‐modified carboxylic acid was not mesogen. The mesophase formation is analyzed as the hydrogen bonding between the Tn and benzoic acid which leads to discrete dimeric supermolecule and enhances the polarity of the core region of the dimeric supermolecule; simultaneously, an increased intramolecular polarity contrast upon replacing alkyl chains by semiperfluorinated chains, which favors a microsegregation, and leads to the fromation of the columnar phase.
A Competitor‐switched Electrochemical Sensor for Detection of DNA
Authors: Fan Hao , Xing Rong , Xu Ying , Chen Miao , Wang Qingjiang , He Pingang , Fang Yuzhi 
Published: November 2010

AbstractA competitor‐switched electrochemical sensor based on a generic displacement strategy was designed for DNA detection. In this strategy, an unmodified single‐stranded DNA (cDNA) completely complementary to the target DNA served as the molecular recognition element, while a hairpin DNA (hDNA) labeled with a ferrocene (Fc) and a thiol group at its terminals served as both the competitor element and the probe. This electrochemical sensor was fabricated by self‐assembling a dsDNA onto a gold electrode surface. The dsDNA was pre‐formed through the hybridization of Fc‐labeled hDNA and cDNA with their part complementary sequences. Initially, the labeled ferrocene in the dsDNA was far from surface of the electrode, the electrochemical sensor exhibited a "switch‐off" mode due to unfavorable electron transfer of Fc label. However, in the presence of target DNA, cDNA was released from hDNA by target DNA, the hairpin‐open hDNA restored its original hairpin structure and the ferrocene approached onto the electrode surface, thus the electrochemical sensor exhibited a "switch‐on" mode accompanying with a change in the current response. The experimental results showed that as low as 4.4×10−10 mol/L target DNA could be distinguishingly detected, and this method had obvious advantages such as facile operation, low cost and reagentless procedure.
Electrocarboxylation of Carbon Dioxide with Polycyclic Aromatic Hydrocarbons Using Ni as the Cathode
Authors: Yuan Gaoqing , Li Liuguan , Jiang Huanfeng , Qi Chaorong , Xie Fengchun 
Published: November 2010

AbstractUsing Ni cathode and Al sacrificial anode, the electrocarboxylation of polycyclic aromatic hydrocarbons (naphthalene, 5‐methylnaphthalene, anthracene, phenanthrene and 1H‐indene) with carbon dioxide (4 MPa) could be successfully performed in an undivided cell containing n‐Bu4NBr‐DMF supporting electrolyte with a constant current at room temperature, affording the corresponding trans‐dicarboxylic acids in good to excellent yields (62% –90%). Among the examined cathode materials (Ni, Pt, Ag, Cu and Zn), Ni and Pt cathodes exhibited a good catalytic activity for the electrocarboxylations. In addition, the experimental results indicated that electrolytic conditions (conducting salts, electricity, CO2 pressure and temperature) could also affect the result of the electrocarboxylation. According to the results of the electrocarboxylations and CV (cyclic voltammetry), a possible electrochemical reaction mechanism was also proposed.
High‐performance Liquid Chromatographic Analysis of Pioglitazone, Gliquidone, Rosuvastatin and Simvastatin in Formulations and Human Serum
Authors: Arayne M. Saeed , Sultana Najma , Mirza Agha Zeeshan , Shamshad Hina 
Published: November 2010

AbstractCo‐administration of HMG‐CoA reductase with antidiabetic drugs is most common since antidiabetic drugs are mostly prescribed for long term therapy. In the present paper, we describe the simultaneous determination of antidiabetic (pioglitazone hydrochloride and gliquidone) in presence of statins (rosvastatin and simvastatin) in formulations and in human serum using RP‐HPLC technique. The serum samples were subjected to protein precipitation with acetonitrile prior to an HPLC analysis. At a flow rate of 1 mL·min−1 isocratic elution was employed, using mobile phase consisting of methanol/water (90:10, V:V), pH 3.50 with phosphoric acid and absorbance was recorded at 235 nm. The assay was reproducible, linear (concentration range of 5–50 μg·mL−1) and accurate. The LOD and LOQ values were 1.32, 0.28, 0.05 and 0.57 μg·mL−1 and 4.39, 0.93, 0.16 and 1.90 μg·mL−1 for pioglitazone hydrochloride, gliquidone, rosvastatin and simvastatin, respectively. There were no interfering peaks due to the excipients present in the pharmaceutical tablet and serum. Thus, the proposed method is simple and suitable for the analysis of active ingredient in tablet form and human serum.
Synthesis and Herbicidal Activity of α‐Hydroxy Phosphonate Derivatives Containing Pyrimidine Moiety
Authors: Song Hong , Mao Huiyu , Shi Deqing 
Published: November 2010

AbstractA series of α‐hydroxy phosphonate derivatives containing pyrimidine moiety were designed and synthesized. Their structures were characterized by IR, 1H NMR, MS and elemental analysis. The results of preliminary herbicidal activities (in vitro) showed that some of the title compounds 2 exhibited moderate herbicidal activities against dicotyledonous weeds (Brassica campestris L), and most of compounds 2 showed better activity against dicotyledonous weeds than monocotyledonous weeds (Echinochloa crus‐galli). Further bioassays (in vivo) indicated that some of the title compounds 2 possessed good and selective herbicidal activity against amaranth pigweed (A. retroflexus) in both pre‐ and post‐emergence treatments at the dose of 1.5 kg/ha. For exmple, compounds 2a, 2b and 2e exhibited 100% inhibition against A. retroflexus in pre‐emergence treatment, and 91.7%, 98.8% and 99.5% inhibition in post‐emergence treatment at the dose of 1.5 kg/ha, respectively.
One Pot Synthesis of Amphiphilic Hyperbranched Poly‐(amino ester) and Its Dynamic Surface Activity
Authors: Gong Zhangshui , Ni Xufeng , Liang Zhenhua , Shen Zhiquan 
Published: November 2010

AbstractAmphiphilic hyperbranched poly(amino ester)s with hydrophilic multi‐ethoxylated triacrylate backbone and hydrophobic long alkyl side chain were firstly synthesized via one pot Michael addition polymerization. The poly‐(amino ester) could dissolve in cold water and self‐assemble into loose micelle. Under 50–1000 ms bubble, the dynamic surface tension (DST) of the poly(amino ester) aqueous solution (0.5 wt%) still maintained in the range of 32–28 mN/m. The aqueous solutions of poly(amino ester)s with different molecular weights showed the lower critical solution temperature (LCST) in the range of 8–50°C, which could also be tuned by its pH. Capped with hydrophobic groups on the terminal units and partially neutralized with acid, the poly(amino ester)s still kept their stable dynamic surfactant behaviors, indicating promising application.
New estimation and feature selection methods in mixture‐of‐experts models
Authors: Khalili Abbas 
Published: November 2010

AbstractWe study estimation and feature selection problems in mixture‐of‐experts models. An$l_2$‐penalized maximum likelihood estimator is proposed as an alternative to the ordinary maximum likelihood estimator. The estimator is particularly advantageous when fitting a mixture‐of‐experts model to data with many correlated features. It is shown that the proposed estimator is root‐$n$consistent, and simulations show its superior finite sample behaviour compared to that of the maximum likelihood estimator. For feature selection, two extra penalty functions are applied to the$l_2$‐penalized log‐likelihood function. The proposed feature selection method is computationally much more efficient than the popular all‐subset selection methods. Theoretically it is shown that the method is consistent in feature selection, and simulations support our theoretical results. A real‐data example is presented to demonstrate the method.The Canadian Journal of Statistics38: 519–539; 2010 © 2010 Statistical Society of Canada
The pseudo‐GEE approach to the analysis of longitudinal surveys
Authors: Carrillo Iván A. , Chen Jiahua , Wu Changbao 
Published: November 2010

AbstractLongitudinal surveys have emerged in recent years as an important data collection tool for population studies where the primary interest is to examine population changes over time at the individual level. Longitudinal data are often analyzed through the generalized estimating equations (GEE) approach. The vast majority of existing literature on the GEE method; however, is developed under non‐survey settings and are inappropriate for data collected through complex sampling designs. In this paper the authors develop a pseudo‐GEE approach for the analysis of survey data. They show that survey weights must and can be appropriately accounted in the GEE method under a joint randomization framework. The consistency of the resulting pseudo‐GEE estimators is established under the proposed framework. Linearization variance estimators are developed for the pseudo‐GEE estimators when the finite population sampling fractions are small or negligible, a scenario often held for large‐scale surveys. Finite sample performances of the proposed estimators are investigated through an extensive simulation study using data from the National Longitudinal Survey of Children and Youth. The results show that the pseudo‐GEE estimators and the linearization variance estimators perform well under several sampling designs and for both continuous and binary responses.The Canadian Journal of Statistics38: 540–554; 2010 © 2010 Statistical Society of Canada
Synthesis and Characterization of 1,3‐Dihalogeno‐2,4‐bis(2,4,6‐tri‐tert‐butylphenyl)‐cyclo‐1,3‐distiba‐2,4‐diazanes, [X–Sb(μ‐NR)]2 (X = F, Cl, Br, and I)
Authors: Lehmann Mathias , Schulz Axel , Villinger Alexander 
Published: November 2010

AbstractThe whole series of four‐membered rings of the type [X–Sb(μ‐NR)]2, containing alternating antimony(III) and nitrogen centers, have been synthesized and fully characterized (X = halogen, R = supermesityl = 2,4,6‐tri‐tert‐butylphenyl = Mes*) and represent rare examples of cyclo‐distiba‐diazanes. The synthesis was carried out starting from the triflate species [TfO–Sb(μ‐NR)]2, which has been generated by utilizing a new synthetic route. By Me3Si–OTf elimination, reactions of [TfO–Sb(μ‐NR)]2 with Me3Si–X yielded the halogen compounds [X–Sb(μ‐NR)]2 with the exception of the fluorine species for which an iodine/fluorine exchange reaction with AgF was successfully applied. The structures of all starting materials, along the reaction pathway, and of all halogen species were determined by single‐crystal X‐ray diffraction. While for the compounds [X–Sb(μ‐NR)]2 (X = OTf, Cl, Br, and I), a molecular structure with no significant intermolecular interactions was observed, the analogous fluorine species[F–Sb(μ‐NR)]2 displays Sb···F van der Waals interactions between the centrosymmetric dimers, which leads to a chain‐like structure in the crystal.