bluuebunny/crossref_metadata_2025_split huggingface dataset:
Purification of phosphoric acid in a gravity wash column
Authors: Chen Aimei , Chen Kui , Zhu Jiawen , Wu Bin , Ji Lijun 
Published: November 2012

AbstractA gravity wash column is a common type of continuous solid–liquid separator, which can be applied in the final step in the suspension crystallisation process of purifying phosphoric acid. In this work, a mathematical model based on material balance was presented for the purification process in a gravity wash column, and the experimental data of suspension crystallisation of phosphoric acid hemi‐hydrate were correlated. The developed purification model can be used to calculate concentration profiles of impurities along the column axis and to predict the effect of operating conditions on the purity of the product stream of phosphoric acid. The model parameters were also estimated by fitting the model with experimental data. © 2012 Canadian Society for Chemical Engineering
A novel analytical method predicts plug boundaries of bingham plastic fluids for laminar flow through annulus
Authors: Bahadori Alireza , Zahedi Gholamreza , Zendehboudi Sohrab 
Published: November 2012

AbstractIn Bingham plastic fluids, a central pre‐yield or plug region exists in the middle of the concentric annular flow. In this region, the local shear stress is less than the dynamic yield stress, so the plug behaves like a rigid solid. This is the main feature that distinguishes the flow of a Bingham plastic fluid from that of a power law fluid. In this work, a simple‐to‐use correlation is developed to predict the boundaries of the plug of Bingham plastic fluids for laminar flow through annulus as a function of dimensionless yield stress and aspect ratio parameters for given values of the rheological constants, pressure gradient and the dimensions of the annulus. The results are found to be in excellent agreement with reported data in the literature with an average absolute deviation of less than 1.7%.The predictive tool is simple and straightforward and can be readily implemented in a standard spreadsheet program. The prime application of the method is as a quick‐and‐easy evaluation tool in engineering studies where plug boundaries of Bingham plastic fluids for laminar flow through annulus are being considered. The method may also serve as a benchmark in numerical and rigorous simulation studies.
Effect of solids loading on agitator just‐suspended speed
Authors: Myers Kevin J. , Janz Eric E. , Fasano Julian B. 
Published: November 2012

AbstractData taken with six solids at numerous Zwietering loadings ranging from near zero to 67 have been used to determine the just‐suspended speed Zwietering loading exponent (Njs ∝ Xn where n is the Zwietering solids loading exponent). When only the loadings range similar to that studied by Zwietering [Zwietering, Chem. Eng. Sci. 1958, 8, 244] is considered (0 < X < 18), the solids loading exponent averaged over all solids is equal to 0.12, essentially the same as the 0.13 reported by Zwietering. However, when the entire loading range is considered (0 < X ≤ 67), a higher average exponent of 0.17 is found and a single power‐law correlation does not accurately describe the experimental data. A piecewise fit of the data indicates that the solids loading exponent increases from an average value of 0.097 at low solids loadings (0 < X ≤ 5) to 0.22 at intermediate loadings (5 ≤ X ≤ 25) and 0.34 for the highest loadings (25 ≤ X ≤ 67).
Identification of LasR Ligands through a Virtual Screening Approach
Authors: Skovstrup Søren , Le Quement Sebastian Thordal , Hansen Thomas , Jakobsen Tim Holm , Harmsen Morten , Tolker‐Nielsen Tim , Nielsen Thomas E. , Givskov Michael , Taboureau Olivier 
Published: November 2012

AbstractWith the widespread occurrence of bacterial resistance to antibiotics, the development of new strategies beyond conventional treatments is a pursuit taken by public health institutions worldwide. LasR, a transcription factor that controls quorum sensing in Pseudomonas aeruginosa, has emerged as an attractive therapeutic target for the next generation of antimicrobial agents. In the present study, a virtual screening workflow combining pharmacophore‐ and structure‐based approaches was used to identify new LasR ligands. Five novel inducers and three inhibitors of LasR activity were validated experimentally by use of a cell‐based assay. Interestingly, these compounds are molecularly distinct from the native signal molecule, N‐3‐oxododecanoyl‐L‐homoserine lactone (OHN), and may serve as lead structures for the design of new drugs. The binding modes of these compounds to the OHN binding site in LasR were predicted and used to identify the key interactions that contribute to the induction and inhibition of LasR activity.
Ketonic Decarboxylation Reaction Mechanism: A Combined Experimental and DFT Study
Authors: Pulido Angeles , Oliver‐Tomas Borja , Renz Michael , Boronat Mercedes , Corma Avelino 
Published: November 2012

AbstractThe ketonic decarboxylation of carboxylic acids has been carried out experimentally and studied theoretically by DFT calculations. In the experiments, monoclinic zirconia was identified as a good catalyst, giving high activity and high selectivity when compared with other potential catalysts, such as silica, alumina, or ceria. It was also shown that it could be used for a wide range of substrates, namely, for carboxylic acids with two to eighteen carbon atoms. The reaction mechanism for the ketonic decarboxylation of acetic acid over monoclinic zirconia was investigated by using a periodic DFT slab model. A reaction pathway with the formation of a β‐keto acid intermediate was considered, as well as a concerted mechanism, involving simultaneous carbon–carbon bond formation and carbon dioxide elimination. DFT results showed that the mechanism with the β‐keto acid was the kinetically favored one and this was further supported by an experiment employing a mixture of isomeric (linear and branched) pentanoic acids.
Organocatalytic Asymmetric Michael Addition of Oxazolones to Arylsulfonyl Indoles: Facile Access to syn‐Configured α,β‐Disubstituted Tryptophan Derivatives
Authors: Cai Chang‐Wu , Zhu Xing‐Li , Wu Song , Zuo Zong‐Le , Yu Liang‐Liang , Qin Da‐Bin , Liu Quan‐Zhong , Jing Lin‐Hai 
Published: November 2012

AbstractEnantioselective Michael addition of oxazolones to in situ generated vinylogous imine intermediates is reported. A series of optically active 3‐alkylindole derivatives with adjacent quaternary and tertiary stereocenters was obtained. The resulting adducts can readily be converted into syn‐configured α,β‐disubstituted tryptophan derivatives without compromising the stereoselectivities.
Association between CYP2A6 genetic polymorphisms and lung cancer: A meta‐analysis of case–control studies
Authors: Liu Tao , Xie Chuan‐Bo , Ma Wen‐Jun , Chen Wei‐Qing 
Published: November 2012

AbstractCytochrome P450 2A6 (CYP2A6) is an enzyme responsible for the metabolism of nicotine and some tobacco‐specific carcinogens (such as N‐nitrosamines). CYP2A6 genetic variations are associated with the activity of the CYP2A6 enzyme, which affects smoking behavior and the rate at which some tobacco‐specific carcinogens are metabolized, which in turn determines the incidence of lung cancer. Several studies have investigated the relationship between CYP2A6 genotypes and lung cancer; however, the results are controversial. In this meta‐analysis, we searched for all studies on the association between CYP2A6 genotypes and lung cancer indexed in the MEDLINE, PubMed, Embase, China Biological Medicine, and Wanfang databases from January 1, 1966 to August 1, 2011. The pooled odds ratios (ORs) for one CYP2A6 mutant allele and two CYP2A6 mutant alleles, in comparison with the wild‐type CYP2A6 gene, were 0.82 [95% confidence interval (CI) = 0.73–0.92] and 0.57 (95% CI = 0.48–0.68), respectively. Furthermore, in two studies of participants who were all smokers, the associations of one CYP2A6 mutant allele and two CYP2A6 mutant alleles with reduced risk of lung cancer were strengthened, and the pooled ORs were 0.71 (95% CI = 0.58–0.87) and 0.47 (95% CI = 0.35–0.62), respectively. However, we did not find statistically significant relationships between CYP2A6 genotypes and lung cancer in studies that included both never smokers and smokers (pooled ORone CYP2A6 mutant allele = 0.88, 95% CI = 0.76–1.01; pooled ORtwo CYP2A6 mutant alleles = 0.61, 95% CI = 0.35–1.06). The results of this meta‐analysis suggest that the reduced‐activity CYP2A6 genotype may decrease the risk of lung cancer in smokers only. Environ. Mol. Mutagen., 2013. © 2012 Wiley Periodicals, Inc.
Mass‐balance modeling of mineral weathering rates and CO2 consumption in the forested, metabasaltic Hauver Branch watershed, Catoctin Mountain, Maryland, USA
Authors: Price Jason R. , Rice Karen C. , Szymanski David W. 
Published: November 2012

ABSTRACTMineral weathering rates and a forest macronutrient uptake stoichiometry were determined for the forested, metabasaltic Hauver Branch watershed in north‐central Maryland, USA. Previous studies of Hauver Branch have had an insufficient number of analytes to permit determination of rates of all the minerals involved in chemical weathering, including biomass. More equations in the mass‐balance matrix were added using existing mineralogic information. The stoichiometry of a deciduous biomass term was determined using multi‐year weekly to biweekly stream‐water chemistry for a nearby watershed, which drains relatively unreactive quartzite bedrock.At Hauver Branch, calcite hosts ~38 mol% of the calcium ion (Ca2+) contained in weathering minerals, but its weathering provides ~90% of the stream water Ca2+. This occurs in a landscape with a regolith residence time of more than several Ka (kiloannum). Previous studies indicate that such old regolith does not typically contain dissolving calcite that affects stream Ca2+/Na+ ratios. The relatively high calcite dissolution rate likely reflects dissolution of calcite in fractures of the deep critical zone.Of the carbon dioxide (CO2) consumed by mineral weathering, calcite is responsible for approximately 27%, with the silicate weathering consumption rate far exceeding that of the global average. The chemical weathering of mafic terrains in decaying orogens thus may be capable of influencing global geochemical cycles, and therefore, climate, on geological timescales. Based on carbon‐balance calculations, atmospheric‐derived sulfuric acid is responsible for approximately 22% of the mineral weathering occurring in the watershed. Our results suggest that rising air temperatures, driven by global warming and resulting in higher precipitation, will cause the rate of chemical weathering in the Hauver Branch watershed to increase until a threshold temperature is reached. Beyond the threshold temperature, increased recharge would produce a shallower groundwater table and reduced chemical weathering rates. Copyright © 2013 John Wiley & Sons, Ltd.
Performance and Robustness of Penalized and Unpenalized Methods for Genetic Prediction of Complex Human Disease
Authors: Abraham Gad , Kowalczyk Adam , Zobel Justin , Inouye Michael 
Published: November 2012

AbstractA central goal of medical genetics is to accurately predict complex disease from genotypes. Here, we present a comprehensive analysis of simulated and real data using lasso and elastic‐net penalized support‐vector machine models, a mixed‐effects linear model, a polygenic score, and unpenalized logistic regression. In simulation, the sparse penalized models achieved lower false‐positive rates and higher precision than the other methods for detecting causal SNPs. The common practice of prefiltering SNP lists for subsequent penalized modeling was examined and shown to substantially reduce the ability to recover the causal SNPs. Using genome‐wide SNP profiles across eight complex diseases within cross‐validation, lasso and elastic‐net models achieved substantially better predictive ability in celiac disease, type 1 diabetes, and Crohn's disease, and had equivalent predictive ability in the rest, with the results in celiac disease strongly replicating between independent datasets. We investigated the effect of linkage disequilibrium on the predictive models, showing that the penalized methods leverage this information to their advantage, compared with methods that assume SNP independence. Our findings show that sparse penalized approaches are robust across different disease architectures, producing as good as or better phenotype predictions and variance explained. This has fundamental ramifications for the selection and future development of methods to genetically predict human disease.
Enhanced cell–material interactions on medium‐pressure plasma‐treated polyhydroxybutyrate/polyhydroxyvalerate
Authors: Jacobs Tinneke , Declercq Heidi , De Geyter Nathalie , Cornelissen Ria , Dubruel Peter , Leys Christophe , Beaurain Arnaud , Payen Edmond , Morent Rino 
Published: November 2012

AbstractIn this article, a medium‐pressure DBD plasma treatment is used to improve the cell–material interaction of a polyhydroxybutyrate/polyhydroxyvalerate (PHB/PHV) film. PHB/PHV is a biodegradable natural polyester, used for different biomedical applications, including sutures, repair devices, and bone marrow scaffolds. The cell adhesion onto PHB/PHV is far less than optimal due to inadequate surface properties, and a surface modification is usually necessary to be able to use the full potential. Medium‐pressure plasma treatments, in different atmospheres, are used to change the surface properties of a PHB/PHV foil. The hydrophilic character could be increased, as shown by water contact angle measurements. X‐ray photoelectron spectroscopy (XPS) revealed an increased oxygen and nitrogen content. Cell culture test with human foreskin fibroblasts showed that the plasma was able to improve cell adhesion (both quantitatively and qualitatively). Both an increase in the number of adherent cells and an improved morphology were obtained after plasma treatment. After 7 days, a confluent cell layer could be observed on plasma‐treated samples. The differences between the three discharge gases are negligible when looking at the improved cell–material interactions. From economical point of view, treatments in air are thus the best choice. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.
New lignocellulose pretreatments using cellulose solvents: a review
Authors: Sathitsuksanoh Noppadon , George Anthe , Zhang Y‐H Percival 
Published: November 2012

AbstractNon‐food lignocellulosic biomass is the most abundant renewable bioresource as a collectable, transportable, and storable chemical energy that is far from fully utilized. The goal of biomass pretreatment is to improve the enzymatic digestibility of pretreated lignocellulosic biomass. Many substrate factors, such as substrate accessibility, lignin content, particle size and so on, contribute to its recalcitrance. Cellulose accessibility to hydrolytic enzymes is believed to be the most important substrate characteristic limiting enzymatic hydrolysis. Cellulose solvents effectively break linkages among cellulose, hemicellulose and lignin, and also dissolve highly‐ordered hydrogen bonds in cellulose fibers accompanied with great increases in substrate accessibility. Here the history and recent advances in cellulose solvent‐based biomass pretreatment are reviewed and perspectives provided for addressing remaining challenges. The use of cellulose solvents, new and existing, provides opportunities for emerging biorefineries to produce a few precursors (e.g. monosaccharides, oligosaccharides, and lignin) for the production of low‐value biofuels and value‐added biochemicals. © 2012 Society of Chemical Industry
Effects of the pre‐treatment alternatives on the treatment of oil‐gas field produced water by nanofiltration and reverse osmosis membranes
Authors: Ozgun Hale , Ersahin Mustafa Evren , Erdem Selime , Atay Burcu , Kose Borte , Kaya Recep , Altinbas Mahmut , Sayili Sema , Hoshan Pelin , Atay Doga , Eren Esra , Kinaci Cumali , Koyuncu Ismail 
Published: November 2012

AbstractBackgroundProduced water is generated in huge volumes from oil and gas production facilities. Different alternatives including physical, chemical, and biological methods can be applied for the treatment of produced waters. In this study, different pre‐treatment alternatives used before a final nanofiltration and reverse osmosis membrane system were evaluated. A membrane bioreactor and pressurized microfiltration and ultrafiltration systems were used in the pre‐treatment stage.ResultsAccording to the results, the highest flux was obtained by the combination of ultrafiltration/microfiltration and nanofiltration; whereas, the maximum removal efficiencies for conductivity and chemical oxygen demand were obtained by the combination of membrane bioreactor and reverse osmosis systems.ConclusionThe results of this study show that the emphasis should be placed on applying the right combination of membrane treatment processes instead of focusing only on pre‐ or final treatment units. © 2012 Society of Chemical Industry
Biting Performance and Skull Biomechanics of a Chisel Tooth Digging Rodent (Ctenomys tuconax; Caviomorpha; Octodontoidea)
Authors: Becerra Federico , Casinos Adrià , Vassallo Aldo Iván 
Published: November 2012

AbstractBiting performance is a key factor in vertebrate groups possessing particular food habits. In subterranean rodents that use the incisors as a digging tool, apart from requirements related to gnawing abrasive diets, the force exerted at the incisors tips must be sufficient to break down soils that are often exceedingly compact. The subterranean genusCtenomysdiversified in the southern portion of South America closely associated with the relatively open environments that characterize that region. This genus is considered a “claw and chisel tooth digger,” that is, during the excavation of their galleries, the animals break down the soil with both the fore‐claws and the incisors. We report here measurements of in vivo bite force in one of the largest species of the genus,C. tuconax, which occupies highland grasslands with compacted soils. We document the combined use of claws and incisors observed under field conditions, also providing measurements of soil compaction in the habitat occupied by this species. We report estimates of bite force at the level of the incisors and cheek teeth calculated from the physiological cross‐sectional area of jaw muscles. To this aim, anatomical and biomechanical analyses of the mandibular apparatus were performed in preserved specimens. We found thatC. tuconaxbites with a higher force than expected for a mammal of its size. To assess anatomical correlates of biting performance, the morphology of the skull and jaw, and incisor second moment of area were compared with those of other caviomorph rodents with different lifestyle. J. Exp. Zool. 319A:74–85, 2013. © 2013 Wiley Periodicals, Inc.
Prediction of Bovine Serum Albumin‐Water Partition Coefficients of a Wide Variety of Neutral Organic Compounds by Means of Support Vector Machine
Authors: Golmohammadi Hassan , Dashtbozorgi Zahra , Acree William E. 
Published: November 2012

AbstractSupport vector machine (SVM) was used to develop a quantitative structure property relationship (QSPR) model that correlates molecular structures to their bovine serum albumin water partition coefficients (KBSA/W). The performance and predictive aptitude of SVM are considered and compared with other methods such as multiple linear regression (MLR) and artificial neural network (ANN) methods. A set of 83 natural organic compounds and drugs were selected and suitable sets of molecular descriptors were calculated. Genetic algorithm (GA) was used to select important molecular descriptors, and linear and nonlinear models were applied to correlate the selected descriptors with the experimental values of log KBSA/W. The correlation coefficients, R, between experimental and predicted log KBSA/W for the validation set by MLR, ANN and SVM are 0.951, 0.986 and 0.991, respectively. Results obtained document the reliability and good predictability of the nonlinear QSPR model to predict partition coefficients of organic compounds. Comparison between the values of statistical parameters demonstrates that the predictive ability of the SVM model is comparable or superior to those obtained by MLR and ANN.
Morphological, mechanical, tribological, and thermal expansion properties of organoclay reinforced polyethylene composites
Authors: Pöllänen Maija , Suihkonen Reija , Nevalainen Katja , Koistinen Arto P. , Suvanto Mika , Vuorinen Jyrki , Pakkanen Tuula T. 
Published: November 2012

AbstractThe morphological, mechanical, thermal, and tribological properties of high‐density polyethylene (HDPE) composites reinforced with organo‐modified nanoclay (3 and 6 wt%) were studied. A commercial maleic anhydride‐based polymeric compatibilizer (PEgMA) was used to improve the adhesion between the polyethylene and clay. Transmission electron microscopy (TEM) characterization of composites revealed that nanoclay exists mainly in a multilayered structure in the HDPE matrix. Mechanical testing of composites showed that Young's modulus and tensile strength increased with nanoclay content. Coefficients of the linear thermal expansion (CLTE) of HDPE–PEgMA–clay composites were slightly lower in the flow direction than those of HDPE–PEgMA. The tribological properties were measured in dry conditions against a steel counterface. The friction coefficient of the matrix was decreased by the addition of clay. Electron microscopic results suggested that the wear mechanism for HDPE and HDPE composites was mainly adhesive. Clay agglomerates were observed on the worn surfaces of the composites, which may partly explain decreased friction. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Transition Metal Complexes with the Schiff Base Ligand 1‐{[2‐(2‐Hydroxyethylamino)ethylimino]methyl}naphthalen‐2‐ol
Authors: Niu Mei‐Ju , Li Huan‐Huan , Wang Su‐Na , Cao Zhi‐Qiang , Sun Da‐Wei , Dou Jian‐Min 
Published: November 2012

AbstractSix transition metal compounds [Cu(H2L)(CH3COO)]·H2O (1), [Cu(H2L)(CH3COO)] (2), [Cu(H2L)](ClO4)·CH3OH (3), 2[Cu(H2L)2] (4), [Co(H2L)2](NO3)·2CH3OH (5), and [Ni(H2L)](NO3) (6) were synthesized by reactions of the Schiff base ligand H3L (1‐{[2‐(2‐hydroxyethyl amino)ethylimino]methyl}naphthalen‐2‐ol) with the corresponding metal salts and characterized by single crystal X‐ray diffraction, elemental analysis, IR and UV/Vis spectroscopy and TG analysis. All compounds are mononuclear molecules, in which the Schiff base ligand exhibits diverse coordination modes and conformations. The N–H···O, O–H···O, and C–H···O inter‐ and intramolecular hydrogen bonding interactions link these molecules into multidimensional network supramolecular structures.
Two pH‐Dependent 1D Copper(II) Coordination Polymers based on a Bis‐triazole‐bis‐amide Ligand: Syntheses, Structures, and Properties
Authors: Lu Qi‐Lin , Zhao Wei , Zhang Ju‐Wen , Wang Xiu‐Li , Luan Jian 
Published: November 2012

AbstractTwo bis‐triazole‐bis‐amide‐based copper(II) coordination polymers, [Cu4(μ3‐OH)2(dtb)(DNBA)6(H2O)2]·2H2O (1) and Cu(dtb)(DNBA)2 (2) [dtb = N,N′‐bis(4H‐1, 2, 4‐triazole)butanamide and HDNBA = 3, 5‐dinitrobenzoic acid], were synthesized and structurally characterized. Polymer 1 shows a one‐dimensional (1D) chain based on tetranuclear CuII cluster and the dtb ligands, whereas polymer 2 exhibits a 1D chain constructed from CuII ions and the dtb ligands. The pH values have a crucial influence on the formation of 1 and 2. In addition, the electrochemical and luminescent properties of 1 and 2 as well as magnetic properties of 1 were investigated.