bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nanocomposite Development with Organically Modified Clay through In Situ Polymerization of Poly(ethylene terephthalate)
Authors: Kim Sung‐Gi , Lofgren Elizabeth A. , Jabarin Saleh A. 
Published: February 2013

ABSTRACTIn situ polymerization of poly(ethylene terephthalate) (PET) organo‐montmorillonite clay nanocomposites was investigated in terms of the natures of organic clay modifiers and their affinities with PET, esterification versus polycondensation mode of clay addition, time and temperature of polymerization, ethylene glycol/terephthalic acid (E/T) ratio, and other process modifications such as foam and diethylene glycol suppression, reactor pressure, and variations in catalyst, antioxidant, and metal stabilizer. The nanocomposites were found to degrade during polymerization. This degradation increased diethylene glycol concentrations and reduced melting temperatures. It also increased carboxyl and decreased hydroxyl end group concentrations from normal PET values, which caused reduced rates of nanocomposite solid‐state polymerization. Cloisite 30B had the best affinity with PET as a result of the hydroxyl groups present in both PET and the organic clay modifier. Polycondensation of Cloisite 30B nanocomposites at 270°C from bis(2‐hydroxyethyl)terephthalate, with an E/T ratio of 1.2:1, yielded the most fully exfoliated nanostructures as verified by X‐ray diffraction and transmission electron microscopy evaluations. © 2013 Wiley Periodicals, Inc. Adv Polym Technol 2013, 32, 21342; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.21342
FRET interaction between pyrene‐tagged β‐hydroxy acid and perylen‐3‐ylmethylmethacrylate co‐N‐dodecylmethacrylamide in film and solution
Authors: Calderon Isen Andrew C. , Lao Kendricks S. , Chua Elvis T. , Romano Edwin , Anore Kristine Haizell S. , Cabatuando Anna Charina R. , Ibabao Marlon Jose P. , Guerrero Raphael A. , So Regina C. 
Published: February 2013

AbstractSynthesis, characterization, and FRET interaction of pyrene‐tagged β‐hydroxy acid and perylen‐3‐ylmethylmethacrylate co‐N‐dodecylmethacrylamide polymer are described. The fluorescent donor, β‐hydroxy acid‐pyrene boronic ester was synthesized from commercially available alkyl ketene dimer via subsequent hydrolysis, reduction and esterification providing the donor. Conversely, the fluorescent acceptor was synthesized by co‐polymerization of N‐dodecylmethacryamide and perylen‐3‐ylmethylmethacrylate, where the latter was prepared from commercially available perylene in three steps. FRET interaction between the donor and acceptor was carried out by titration and monitored using fluorescence spectroscopy. Fluorescence quenching and enhancement in both film and solution formats were observed; furthermore, a more prominent lipophilic‐induced interaction was observed in solution. Fluorescence enhancement (at 460 nm) is higher for the acceptor and quenching efficiency (at 420 nm) is higher for donor‐acceptor pair, pyrene‐tagged β‐hydroxy acid and perylen‐3‐ylmethylmethacrylate co‐N‐dodecylmethacryl‐amide polymer, compared to control, pyrene boronic ester. The quenching is due to dynamic quenching between the donor and acceptor. Furthermore, aggregation was not observed from the pyrene‐tagged β‐hydroxy acid ester donor as the concentration of the solution is increased up to 3000 ppm. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Polymer stain resistance: Prediction versus experiment
Authors: Narses Sebastien , Sadaka Faten , Brachais Claire‐Hélène , Couvercelle Jean‐Pierre 
Published: February 2013

AbstractThe coloration of different polymer films (from commodity and packaging films to performance films) by contact with various food coloring substances was evaluated. For this purpose, both solubility parameters as a prediction tool, and immersion experiments for time range between 24 and 1000 h were established. The two predicting tools are the Hoy and Hoftyzer‐Van Krevelen (HVK) methods. For PE and PP, HVK's method is preferred for predicting coloration. Neither of the HVK's and Hoy's methods was able to establish a coloration prediction for PET while both methods could predict the staining of PEEK. The coloration of partially and fully fluorinated polymers is well predicted by the Hoy's method. The behavior of PP/PA and PP/PA/PP multilayer films was also studied. Crystallinity degree of polymers, temperature and concentration of coloring molecules are also important parameters, which are not taken into account in solubility theories. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Synthesis of Antitumor‐Active Betulinic Acid‐Derived Hydroxypropargylamines by Copper‐Catalyzend Mannich Reactions
Authors: Csuk René , Nitsche Christoph , Sczepek Ronny , Schwarz Stefan , Siewert Bianka 
Published: February 2013

AbstractSeveral novel betulin derivates were prepared using Mannich reactions as a key step. Starting from 3‐ethynyl‐3‐hydroxy‐lup‐20(29)‐ene derivatives, copper‐catalyzed Mannich reactions yielded hydroxypropargyl ammonium hydrochlorides or their corresponding methiodides. All compounds were screened in a sulforhodamine B assay for their antitumor activity using a panel of 9 human cancer cell lines. Some of these compounds showed significant cytotoxicity; they act by triggering apoptotic cell death as shown by additional acridine orange/propidium iodide assays, Trypan blue tests, DNA laddering experiments, and investigations of the cell cycle.
Nepem‐211 ion exchange conductive membrane immobilized tris(2,2´‐bipyridyl) ruthenium(II) electrogenerated chemiluminescence flow sensor for high‐performance liquid chromatography and its application
Authors: Li Yongbo , Zhang Zhujun 
Published: February 2013

ABSTRACTWe developed a sensitive and robust electrogenerated chemiluminescence (ECL) flow sensor based on Ru(bpy)32+ immobilized with a Nepem‐211 perfluorinated ion exchange conductance membrane, which has robustness and stability under a wide range of chemical and physical conditions, good electrical conductivity, isotropy and a high exchange capacity for immobilization of Ru(bpy)32+. The flow sensor has been used as a post‐column detector in high‐performance liquid chromatography for determination of erythromycin and clarithromycin in honey and pork, and tricyclic antidepressant drugs in human urine. Under optimal conditions, the linear ranges were 0.03–26 ng/μL and 0.01–1 ng/μL for macrolides and tricyclic antidepressant drugs, respectively. The detection limits were 0.02, 0.01, 0.01, 0.06 and 0.003 ng/μL for erythromycin, clarithromycin, doxepin, amitriptyline and clomipramine, respectively. There is no post‐column reagent addition. In addition to the conservation expensive reagents, the experimental setup was simplified. The flow sensor was used for 2 years with high sensitivity and stability. Copyright © 2013 John Wiley & Sons, Ltd.
Renewable bio ionic liquids‐water mixtures‐mediated selective removal of lignin from rice straw: Visualization of changes in composition and cell wall structure
Authors: Hou Xue‐Dan , Li Ning , Zong Min‐Hua 
Published: February 2013

AbstractPretreatment of rice straw by using renewable cholinium amino acids ionic liquids ([Ch][AA] ILs)‐water mixtures and the subsequent enzymatic hydrolysis of the residues were conducted in the present work. Of the eight mixtures composed of ILs and water, most were found to be effective for rice straw pretreatment. After pretreatment with 50% ILs‐water mixtures, the enzymatic digestion of the lignocellulosic biomass was enhanced significantly, thus leading to satisfactory sugar yields of >80% for glucose and approximately 50% for xylose. To better understand the ILs pretreatment mechanism, confocal laser scanning microscopy combined with immunolabeling and transmission electron microscopy were used to visualize changes in the contents and distribution of two major components—lignin and xylan. The results coupled with changes in chemical structures (infrared spectra) of the substrates indicated occurrence of extensive delignification, especially in cell corner and compound middle lumen of cell walls, which made polysaccharides more accessible to enzymes. This pretreatment process is promising for large‐scale application because of the high sugar yields, easy handling, being environmentally benign and highly tolerant to moisture, and significantly reduced cost and energy consumption. Biotechnol. Bioeng. 2013; 110: 1895–1902. © 2013 Wiley Periodicals, Inc.
Periplasmic expression of carbonic anhydrase in Escherichia coli: A new biocatalyst for CO2 hydration
Authors: Patel Tushar N. , Park Ah‐Hyung Alissa , Banta Scott 
Published: February 2013

AbstractCarbonic anhydrase is a valuable and efficient catalyst for CO2 hydration. Most often the free enzyme is employed which complicates catalyst recycling, and can increase cost due to the need for protein purification. Immobilization of the enzyme may address these shortcomings. Here we report the development of whole‐cell biocatalysts for CO2 hydration via periplasmic expression of two forms of carbonic anhydrase in Escherichia coli using two different targeting sequences. The enzymatic turnover numbers (kcat) and catalytic efficiencies (kcat/KM) were decreased by an order of magnitude as compared to the free soluble enzyme, indicating the introduction of transport limitations. However, the thermal stabilities were improved for most configurations (>88% activity retention up to 95°C for three of four whole‐cell biocatalysts), operational stabilities were more than satisfactory (100% retention after 24 h of use for all four whole‐cell biocatalysts), and CO2 hydration was significantly enhanced relative to the uncatalyzed reaction (∼50–70% increase in CaCO3 precipitate formed). A significant advantage of the whole‐cell approach is that protein purification is no longer necessary, and the cells can be easily separated and recycled in future applications including biofuel production, biosensors, and carbon capture and storage. Biotechnol. Bioeng. 2013; 110: 1865–1873. © 2013 Wiley Periodicals, Inc.
Phosphite‐Thiazoline versus Phosphite‐Oxazoline for Pd‐Catalyzed Allylic Substitution Reactions: A Case for Comparison
Authors: Mazuela Javier , Pàmies Oscar , Diéguez Montserrat 
Published: February 2013

AbstractWe have expanded the ligand design of one of the most successful phosphite‐oxazoline ligands, derived from hydroxyl amino acid derivatives, in Pd‐catalyzed allylic alkylation by replacing the oxazoline group with a thiazoline moiety. These phosphite‐thiazoline ligands have been evaluated in the Pd‐catalyzed allylic substitution of a wide range of mono‐, di‐, and trisubstituted substrates with several carbon nucleophiles, such as the less studied α‐substituted malonates and β‐diketones. For comparison we have also expanded our previous work on phosphite‐oxazoline to carbon nucleophiles other than dimethyl malonate and to the alkylation of trisubstituted substrates. For hindered substrates such as disubstituted rac‐1,3‐diphenyl‐3‐acetoxyprop‐1‐ene and trisubstituted rac‐1,1,‐diphenyl‐1‐hepten‐3‐yl acetate and rac‐1,3,3‐triphenylprop‐2‐enyl acetate, enantioselectivities (ee values up to >99 %) are best obtained with phosphite‐oxazoline ligands, whereas for unhindered cyclic substrates such as rac‐3‐acetoxycyclohexene, rac‐3‐acetoxycyclopentene, and rac‐3‐acetoxycycloheptene, enantioselectivities (ee values up to 94 %) improved considerably with phosphite‐thiazoline ligands. In the case of monosubstituted substrates, the regio‐ and enantioselectivities obtained with both ligand types were comparable and excellent (regioselectivities up to 90 % and ee values up to 95 %). Therefore, by correctly combining substrate and ligand type (phosphite‐oxazoline or phosphite‐thiazoline), we have identified one of the few catalytic systems that provide high regio‐ and enantioselectivities in both enantiomers of the alkylation product for a wide range of hindered and unhindered mono‐, di‐, and trisubstituted substrates with several carbon nucleophiles. We have also discussed the synthesis and characterization of Pd‐π‐allyl intermediates to provide greater insight into the origin of enantioselectivity in these catalytic systems.
A Note on the Incremental Validity of Integrity Tests beyond Standard Personality Inventories for the Criterion of Counterproductive Behaviour
Authors: Marcus Bernd , Ashton Michael C. , Lee Kibeom 
Published: February 2013

AbstractAlthough the validity of integrity tests for predicting the focal criterion of counterproductive work behaviour (CWB) is well‐established, little research has yet addressed the incremental CWB‐related validity of integrity tests beyond basic personality traits. The present research addresses this issue by re‐analyzing data adopted from Marcus, Lee, and Ashton (2007), in which four different overt and personality‐based integrity tests and the HEXACO‐Personality Inventory (Lee & Ashton, 2004) were related to CWB. Integrity accounted for practically significant proportions of incremental variance beyond personality across all integrity tests, yet effect sizes of incremental validity dropped considerably if Honesty‐Humility was added to traditional Big Five dimensions. In addition, findings suggest that CWB is best predicted by a combination of integrity and personality tests. Copyright © 2013 ASAC. Published by John Wiley & Sons, Ltd.
Generalized estimating equations for mixtures with varying concentrations
Authors: Maiboroda Rostyslav , Sugakova Olena , Doronin Alexey 
Published: February 2013

AbstractA finite mixture model is considered in which the mixing probabilities vary from observation to observation. A parametric model is assumed for one mixture component distribution, while the others are nonparametric nuisance parameters. Generalized estimating equations (GEE) are proposed for the semi‐parametric estimation. Asymptotic normality of the GEE estimates is demonstrated and the lower bound for their dispersion (asymptotic covariance) matrix is derived. An adaptive technique is developed to derive estimates with nearly optimal small dispersion. An application to the sociological analysis of voting results is discussed. The Canadian Journal of Statistics 41: 217–236; 2013 © 2013 Statistical Society of Canada
Computational Studies Identifying Entry Inhibitor Scaffolds Targeting the Phe 43 Cavity of HIV‐1 gp120
Authors: Tintori Cristina , Selvaraj Manikandan , Badia Roger , Clotet Bonaventura , Esté José A. , Botta Maurizio 
Published: February 2013

AbstractTargeting protein–protein interactions, such as the HIV‐1 gp120—CD4 interface, has become a cutting‐edge approach in the current drug discovery scenario. Many small molecules have been developed so far as inhibitors of the interaction between CD4 and HIV‐1 gp120. However, due to a variety of reasons such as solubility, drug toxicity and drug resistance, these inhibitors have failed to prove clinically useful. As such, the identification of novel compounds that bind to protein–protein interactions is still a research area of considerable interest. Here, a structure‐based virtual screening approach was successfully applied with the aim of identifying novel HIV‐1 entry inhibitors targeting the Phe 43 pocket of HIV‐1 gp120. Several compounds able to inhibit viral replication in cell culture were identified, with the best agent endowed with an EC50 value of 0.9 μM. Inactivity of all the identified hits toward a mutant (Met 475 Ile) strain strongly suggests that they interact in the Phe 43 cavity of gp120, as intended. Remarkably, all of these small molecules have a chemical scaffold unrelated to any known class of entry inhibitors reported thus far. Overall, our strategy led to the identification of four novel chemical scaffolds that inhibit HIV‐1 replication through the destabilization of the HIV‐1 gp120–CD4 interface.
Gårding's Theory of Hyperbolic Polynomials
Authors: Harvey F. Reese , Lawson H. Blaine 
Published: February 2013

AbstractThis paper presents a simple, self‐contained account of Gårding's theory of hyperbolic polynomials, together with a recent convexity result of Bauschke‐Güler‐Lewis‐Sendov and an inequality of Gurvits. This account begins by establishing some new results. The first concerns the existence of a pointwise arrangement of the eigenvalues so that they become global real analytic functions. The second asserts that the associated “branches” are independent of the choice of hyperbolic direction. © 2013 Wiley Periodicals, Inc.
The Intermolecular SH⋅⋅⋅Y (Y=S,O) Hydrogen Bond in the H2S Dimer and the H2S–MeOH Complex
Authors: Bhattacherjee Aditi , Matsuda Yoshiyuki , Fujii Asuka , Wategaonkar Sanjay 
Published: February 2013

AbstractThe nature of the SH⋅⋅⋅S hydrogen‐bonding interaction in the H2S dimer and its structure has been the focus of several theoretical studies. This is partly due to its structural similarity and close relationship with the well‐studied water dimer and partly because it represents the simplest prototypical example of hydrogen bonding involving a sulfur atom. Although there is some IR data on the H2S dimer and higher homomers from cold matrix experiments, there are no IR spectroscopic reports on SH⋅⋅⋅S hydrogen bonding in the gas phase to‐date. We present experimental evidence using VUV ionization‐detected IR‐predissociation spectroscopy (VUV‐ID‐IRPDS) for this weak hydrogen‐bonding interaction in the H2S dimer. The proton‐donating SH bond is found to be red‐shifted by 31 cm−1. We were also able to observe and assign the symmetric (ν1) stretch of the acceptor and an unresolved feature owing to the free SH of the donor and the antisymmetric (ν3) SH stretch of the acceptor. In addition we show that the heteromolecular H2S–MeOH complex, for which both SH⋅⋅⋅O and OH⋅⋅⋅S interactions are possible, is S‐H⋅⋅⋅O bound.
Regioselective Nitration of Aromatics with Nanomagnetic Solid Superacid SO42−/ZrO2‐MxOy‐Fe3O4 and Its Theoretical Studies
Authors: Wang Peng Cheng , Zhu Jie , Liu Xiang , Lu Ting Ting , Lu Ming 
Published: February 2013

AbstractA series of micro‐ and nanosulfated zirconia loaded on Fe3O4 or other metal oxides (SO42−/ZrO2‐MxOy‐Fe3O4 (M=Ti4+, V5+, and Zn2+)) was prepared, characterized, and used in nitration. The nitration conditions with these solid superacids were then optimized to achieve the best regioselectivity and improve the performances of the catalysts as well. In the experimental results, SZTF (SO42−/ZrO2‐TiO2‐Fe3O4) showed excellent catalytic activity and it increased the surface area of SO42−/ZrO2 by up to 15 %. The increase not only facilitated the generation of NO2+, but also provided more opportunities for metal ions to interact with aromatic compounds. With chlorobenzene as substrate, theoretical research on its geometric parameters, electron clouds, and electron spin density was used to investigate the interaction between transition metals and chlorobenzene.
Electrooxidation of Ethylene Glycol and Glycerol on Pd‐(Ni‐Zn)/C Anodes in Direct Alcohol Fuel Cells
Authors: Marchionni Andrea , Bevilacqua Manuela , Bianchini Claudio , Chen Yan‐Xin , Filippi Jonathan , Fornasiero Paolo , Lavacchi Alessandro , Miller Hamish , Wang Lianqin , Vizza Francesco 
Published: February 2013

AbstractThe electrooxidation of ethylene glycol (EG) and glycerol (G) has been studied: in alkaline media, in passive as well as active direct ethylene glycol fuel cells (DEGFCs), and in direct glycerol fuel cells (DGFCs) containing Pd‐(Ni‐Zn)/C as an anode electrocatalyst, that is, Pd nanoparticles supported on a Ni–Zn phase. For comparison, an anode electrocatalyst containing Pd nanoparticles (Pd/C) has been also investigated. The oxidation of EG and G has primarily been investigated in half cells. The results obtained have highlighted the excellent electrocatalytic activity of Pd‐(Ni‐Zn)/C in terms of peak current density, which is as high as 3300 A g(Pd)−1 for EG and 2150 A g(Pd)−1 for G. Membrane‐electrode assemblies (MEA) have been fabricated using Pd‐(Ni‐Zn)/C anodes, proprietary Fe‐Co/C cathodes, and Tokuyama A‐201 anion‐exchange membranes. The MEA performance has been evaluated in either passive or active cells fed with aqueous solutions of 5 wt % EG and 5 wt % G. In view of the peak‐power densities obtained in the temperature range from 20 to 80 °C, at Pd loadings as low as 1 mg cm−2 at the anode, these results show that Pd‐(Ni‐Zn)/C can be classified amongst the best performing electrocatalysts ever reported for EG and G oxidation.
Application of dynamic counter circuits in programmable digital pixel sensor architectures
Authors: Habibi M. 
Published: February 2013

ABSTRACTIn this paper, a high dynamic range digital pixel sensor (DPS) is presented. Each pixel receives light illumination and converts the intensity level to a digital code. The analog‐to‐digital conversion is performed in‐pixel. The pixel structure incorporates light to pulse signal converter and compact in‐pixel dynamic counter to convert the pulse signal to binary coded data. Different variations of the custom design dynamic counters are analyzed in a 0.18 µm technology, and their application in the DPS is investigated. It is shown that due to the limited clock frequency required in the sensor pixel, the dynamic counter can be incorporated as a pulse to binary code converter. Performance specifications such as power consumption, dynamic range and resolution of the presented structure are investigated using a 100 × 100 pixel sensor. The presented sensor is an effective solution for use in digital field programmable smart image sensors and vision chips since the pixel output is a regular binary code while no global digital counter bus is required. The fill factor of the presented design remains close to that of typical DPSs. Copyright © 2013 John Wiley & Sons, Ltd.
The Application of ZnO Nanoparticles Containing Polyoxometalates in Dye‐Sensitized Solar Cells
Authors: Li Jiansheng , Sang Xiaojing , Chen Weilin , Qin Chao , Wang Shiming , Su Zhongmin , Wang Enbo 
Published: February 2013

AbstractZnO nanoparticles (NPs) containing H3PW12O40 polyoxometalates (POMs) were firstly synthesized by a simple solvothermal route. The photoanodes of dye‐sensitized solar cells (DSSCs) were assembled with the as‐prepared ZnO powder containing H3PW12O40. A comparative experiment in the absence of POMs was carried out to investigate the influence of H3PW12O40. Furthermore, the effects of other Keggin‐type POMs including W series, Mo series, and the potassium salt K3PW12O40 were studied and different concentrations of H3PW12O40 were utilized to investigate the impact on the performance of DSSCs on the basis of the above research. The results demonstrate that the W‐containing POM series HxMW12O40 (M = P, x = 3; M = Si, Ge, x = 4) significantly enhances the performance of DSSCs by increasing electronic lifetimes and reducing dark currents. The overall solar‐to‐electric energy conversion efficiency reached a maximum of 2.70 % in the presence of H3PW12O40, which is an improvement of 49.2 % compared to the efficiency without H3PW12O40. A suitable H3PW12O40 concentration is crucial.