bluuebunny/crossref_metadata_2025_split huggingface dataset:
Wear characteristics of styrene butadiene rubber/natural rubber blends with varying carbon blacks by DIN abrader and mining rock surfaces
Authors: Pal Kaushik , Das Tanya , Rajasekar R. , Pal Samir K. , Das Chapal K. 
Published: October 2008

AbstractIn this study, nine rubber compounds were produced by varying the proportions of natural rubber (NR), styrene butadiene rubber (SBR), and four different carbon blacks. Tensile and tear properties are enhanced by the addition of intermediate super abrasion furnace (ISAF) N231, and modulus increases for the compounds containing N234 carbon blacks. The wear behavior of the prepared rubber vulcanizates against various rocks, such as, granite, shale, schist, sandstone, coal, and concrete, at 4.4 N normal load and 0.8 m/s relative sliding speed were studied in a specially fabricated experimental setup. The DIN abrasion testing results show good abrasion resistant properties of 70 phr NR and 30 phr SBR with N231 grade ISAF type carbon black. Also, moderate abrasion resistance is found in rubber compound containing 80 phr NR and 20 phr SBR with N234 grade ISAF type of carbon black. Out of the various rock types, the schist and sandstone are observed to be highly abrasive against the prepared rubber compounds. The microscopic examination of the abraded rubber surfaces has indicated the formation of longitudinal grooves against harder rocks and transverse ridges against softer rocks. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
New relations between similarity measures for vectors based on vector norms
Authors: Egghe Leo 
Published: October 2008

AbstractThe well‐known similarity measures Jaccard, Salton's cosine, Dice, and several related overlap measures for vectors are compared. While general relations are not possible to prove, we study these measures on the “trajectories” of the form $||\overrightarrow X || = a||\overrightarrow Y ||$, where a > 0 is a constant and ||·|| denotes the Euclidean norm of a vector. In this case, direct functional relations between these measures are proved. For Jaccard, we prove that it is a convexly increasing function of Salton's cosine measure, but always smaller than or equal to the latter, hereby explaining a curve, experimentally found by Leydesdorff. All the other measures have a linear relation with Salton's cosine, reducing even to equality, in case a = 1. Hence, for equally normed vectors (e.g., for normalized vectors) we, essentially, only have Jaccard's measure and Salton's cosine measure since all the other measures are equal to the latter.
SpamED: A spam E‐mail detection approach based on phrase similarity
Authors: Pera Maria Soledad , Ng Yiu‐Kai 
Published: October 2008

AbstractE‐mail messages are unquestionably one of the most popular communication media these days. Not only are they fast and reliable but also free in general. Unfortunately, a significant number of e‐mail messages received by e‐mail users on a daily basis are spam. This fact is annoying since spam messages translate into a waste of the user's time in reviewing and deleting them. In addition, spam messages consume resources such as storage, bandwidth, and computer‐processing time. Many attempts have been made in the past to eradicate spam; however, none has proven highly effective. In this article, we propose a spam e‐mail detection approach, called SpamED, which uses the similarity of phrases in messages to detect spam. Conducted experiments not only verify that SpamED using trigrams in e‐mail messages is capable of minimizing false positives and false negatives in spam detection but it also outperforms a number of existing e‐mail filtering approaches with a 96% accuracy rate.
A global map of science based on the ISI subject categories
Authors: Leydesdorff Loet , Rafols Ismael 
Published: October 2008

AbstractThe decomposition of scientific literature into disciplinary and subdisciplinary structures is one of the core goals of scientometrics. How can we achieve a good decomposition? The ISI subject categories classify journals included in the Science Citation Index (SCI). The aggregated journal‐journal citation matrix contained in the Journal Citation Reports can be aggregated on the basis of these categories. This leads to an asymmetrical matrix (citing versus cited) that is much more densely populated than the underlying matrix at the journal level. Exploratory factor analysis of the matrix of subject categories suggests a 14‐factor solution. This solution could be interpreted as the disciplinary structure of science. The nested maps of science (corresponding to 14 factors, 172 categories, and 6,164 journals) are online at http://www.leydesdorff.net/map06. Presumably, inaccuracies in the attribution of journals to the ISI subject categories average out so that the factor analysis reveals the main structures. The mapping of science could, therefore, be comprehensive and reliable on a large scale albeit imprecise in terms of the attribution of journals to the ISI subject categories.
Shifting of the distribution of aromatic monomer‐units in polyhydroxyalkanoic acid to longer units by salicylic acid in Pseudomonas fluorescens BM07 grown with mixtures of fructose and 11‐phenoxyundecanoic acid
Authors: Choi Mun Hwan , Xu Ju , Rho Jong Kook , Shim Ji Hoon , Yoon Sung Chul 
Published: October 2008

AbstractMedium‐chain‐length‐polyhydroxyalkanoic acids (MCL‐PHAs) formed in Pseudomonas spp. have a rather broad distribution of monomer‐units whose precursors are supplied via β‐oxidation degradation of MCL fatty acids fed as the carbon source and/or via PhaG enzyme catalyzing the acyl‐group transfer from 3‐hydroxyacyl‐ACPs derived from acetyl‐CoA to coenzyme A. It was found that salicylic acid (SA), in a concentration dependent manner, suppressed the accumulation of PHA in Pseudomonas fluorescens BM07 from fructose as well as shifted the distribution of monomer‐units derived from a MCL fatty acid co‐added as carbon source (e.g., 11‐phenoxyundecanoic acid (11‐POU)) to longer monomer‐units. Both SA and acrylic acid were found to induce high accumulations of 3‐ketohexanoic acid in BM07 wild‐type cells grown with n‐hexanoic acid as well as to inhibit the formation of acetyl‐CoA from acetoacetyl‐CoA by BM07 cell extract, suggesting that 3‐ketoacyl‐CoA thiolase is their common β‐oxidation target. The structural motif of acrylic acid present in the molecular structure of SA may self‐explain the similar actions of the two inhibitors. A comparison of monomer modulation between BM07 wild‐type and ΔphaG mutant cells grown on the mixtures of fructose and 11‐POU revealed that both PhaG and β‐oxidation inhibitor may play a critical role in the synthesis of PHA with longer side‐chain ω‐functional substitutions. Biotechnol. Bioeng. 2009;102: 1209–1221. © 2008 Wiley Periodicals, Inc.
Maintenance and growth requirements in the metabolism of Debaryomyces hansenii performing xylose‐to‐xylitol bioconversion in corncob hemicellulose hydrolyzate
Authors: Rivas Beatriz , Torre Paolo , Domínguez José Manuel , Converti Attilio 
Published: October 2008

AbstractIn order to improve the biotechnological production of xylitol, the metabolism of Debaryomyces hansenii NRRL Y‐7426 in corncob hemicellulose hydrolyzate has been investigated under different conditions, where either maintenance or growth requirements predominated. For this purpose, the experimental results of two sets of batch bioconversions carried out alternatively varying the starting xylose concentration in the hydrolyzate (65.6 ≤ S0 ≤ 154.7 g L−1) or the initial biomass level (3.0 ≤ X0 ≤ 54.6 gDM L−1) were used to fit a metabolic model consisting of carbon material and ATP balances based on five main activities, namely fermentative assimilation of pentoses, semi‐aerobic pentose‐to‐pentitol bioconversion, biomass growth on pentoses, catabolic oxidation of pentoses, and acetic acid and NADH regeneration by the electron transport system. Such an approach allowed separately evaluating the main bioenergetic constants of this microbial system, that is, the specific rates of ATP and xylose consumption due to maintenance (mATP = 21.0 mmolATP C−molDM−1h−1; mXyl = 6.5 C‐mmolXyl C−molDM−1h−1) and the true yields of biomass on ATP (YATPmax = 0.83 C‐molDM molATP−1) and on xylose (YXylmax = 0.93 C‐molDM C‐molXyl−1). The results of this study highlighted that the system, at very high S0 and X0 values, dramatically increased its energy requirements for cell maintenance, owing to the occurrence of stressing conditions. In particular, for S0 > 130 g L−1, these activities required an ATP consumption of about 2.1 molATP L−1, that is, a value about seven‐ to eightfold that observed at low substrate concentration. Such a condition led to an increase in the fraction of ATP addressed to cell maintenance from 47% to 81%. On the other hand, the very high percentage of ATP addressed to maintenance (>96%) at very high cell concentration (X0 ≥ 25 gDM L−1) was likely due to the insufficient substrate to sustain the growth. Biotechnol. Bioeng. 2009;102: 1062–1073. © 2008 Wiley Periodicals, Inc.
High‐level bacterial cellulase accumulation in chloroplast‐transformed tobacco mediated by downstream box fusions
Authors: Gray Benjamin N. , Ahner Beth A. , Hanson Maureen R. 
Published: October 2008

AbstractThe Thermobifida fusca cel6A gene encoding an endoglucanase was fused to three different downstream box (DB) regions to generate cel6A genes with 14 amino acid fusions. The DB‐Cel6A fusions were inserted into the tobacco (Nicotiana tabacum cv. Samsun) chloroplast genome for protein expression. Accumulation of Cel6A protein in transformed tobacco leaves varied over approximately two orders of magnitude, dependent on the identity of the DB region fused to the cel6A open reading frame (ORF). Additionally, the DB region fused to the cel6A ORF affected the accumulation of Cel6A protein in aging leaves, with the most effective DB regions allowing for high level accumulation of Cel6A protein in young, mature, and old leaves, while Cel6A protein accumulation decreased with leaf age when less effective DB regions were fused to the cel6A ORF. In the most highly expressed DB‐Cel6A construct, enzymatically active Cel6A protein accumulated at up to 10.7% of total soluble leaf protein (%TSP). The strategy used for high‐level endoglucanase expression may be useful for expression of other cellulolytic enzymes in chloroplasts, ultimately leading to cost‐effective heterologous enzyme production for cellulosic ethanol using transplastomic plants. Biotechnol. Bioeng. 2009;102: 1045–1054. © 2008 Wiley Periodicals, Inc.
Tricalcium phosphate nanoparticles enable rapid purification, increase transduction kinetics, and modify the tropism of mammalian viruses
Authors: Dreesen Imke A.J. , Lüchinger Norman A. , Stark Wendelin J. , Fussenegger Martin 
Published: October 2008

AbstractAdenoviral, adeno‐associated viral, and retroviral particles are chosen as gene delivery shuttles in more than 50% of all gene therapy clinical trials. Bulk availability of clinical‐grade viral particles and their efficiency to transduce the therapeutic cargo into specific target cells remain the most critical bottlenecks in gene therapy applications to date. Capitalizing on the flame‐spray technology for the reproducible economic large‐scale production of amorphous tricalcium phosphate nanoparticulate powders (ATCP), we designed a scalable ready‐to‐use gravity‐flow column set‐up for the straightforward concentration and purification of transgenic adenoviral, adeno‐associated viral, and lentiviral particles. Specific elution buffers enabled rapid release of viral particles from the ATCP matrix of the column and provided high‐titer virus preparations in an unsurpassed period of time. The interaction of ATCP with adenoviral, adeno‐associated viral, and lentiviral particles in solution increased the transduction kinetics of several mammalian cell lines in culture. The nanoparticles were also able to modify the tropism of murine leukemia virus (MLV) towards transduction of human cells. Based on these findings, we believe that the use of flame‐spray tricalcium phosphate nanoparticles will lead to important progress in the development of future gene therapy initiatives. Biotechnol. Bioeng. 2009;102: 1197–1208. © 2008 Wiley Periodicals, Inc.
A study of monoclonal antibody‐producing CHO cell lines: What makes a stable high producer?
Authors: Chusainow Janet , Yang Yuan Sheng , Yeo Jessna H.M. , Toh Poh Choo , Asvadi Parisa , Wong Niki S.C. , Yap Miranda G.S. 
Published: October 2008

AbstractGenerating stable, high‐producing cell lines for recombinant protein production requires an understanding of the potential limitations in the cellular machinery for protein expression. In order to increase our understanding of what makes a stable high producer, we have generated a panel of 17 recombinant monoclonal antibody expressing Chinese hamster ovary subclones (CHO‐mAb) with specific productivities ranging between 3 and 75 pg cell−1 day−1 using the dihydrofolate reductase (dhfr) expression system and compared the molecular features of these high‐ and low‐producer clones. The relative heavy chain (HC) and light chain (LC) transgene copy numbers and mRNA levels were determined using real‐time quantitative PCR (RT qPCR). We observed that not only higher transgene copy numbers and mRNA levels of both HC and LC were characteristic for the high‐producer clones as compared to the low‐producer clones but also a more favorable HC to LC transgene copy numbers ratio. By studying the long‐term stability of the CHO‐mAb subclones in the absence of methotrexate (MTX) selective pressure over 36 passages we observed a 35–92% decrease in volumetric productivity, primarily caused by a significant decrease in HC and LC mRNA levels with little change in the transgene copy numbers. Using Southern blot hybridization we analyzed the HC and LC transgene integration patterns in the host chromosome and their changes in course of gene amplification and long‐term culturing. We observed that MTX‐induced gene amplification caused chromosomal rearrangements resulting in clonal variability in regards to growth, productivity, and stability. No further obvious DNA rearrangements occurred during long‐term culturing in the absence of MTX, indicating that other mechanisms were responsible for the decreased transcription efficiency. Our results implicate that the amplified transgene sequences were arranged in tandem repeats potentially triggering repeat‐induced gene silencing. We hypothesize that the decline in transgene mRNA levels upon long‐term culturing without MTX was mainly caused by transgene silencing consequently leading to a loss in mAb productivity. The exact molecular mechanisms causing production instability are not yet fully understood. The herein described extensive characterization studies could help understand the limitations to high‐level, stable recombinant protein production and find ways to improving and accelerating the process for high‐producer cell line generation and selection. Biotechnol. Bioeng. 2009;102: 1182–1196. © 2008 Wiley Periodicals, Inc.
Role of surfactant on the proteolysis of aqueous bovine serum albumin
Authors: Porcel E.M. Rodriguez , Foose L.L. , Svitova T.F. , Blanch H.W. , Prausnitz J.M. , Radke C.J. 
Published: October 2008

AbstractNonionic and ionic surfactants diminish the initial rate of proteolysis of aqueous bovine serum albumin (BSA) by subtilisin Carlsberg. Surfactants studied include: nonionic tetraethylene glycol monododecyl ether (C12E4); anionic sodium dodecyl sulfate (SDS), anionic sodium dodecylbenzenesulfonate (SDBS), and cationic dodecyltrimethylamonium bromide (DTAB). Kinetic data are obtained using fluorescence emission. Special attention is given to enzyme kinetic specificity determined by fitting initial‐rate data to the Michaelis–Menten model. All surfactants reduce the rate of proteolysis, most strongly at concentrations near and above the critical micelle concentration (CMC). Circular dichroism (CD), tryptophan/tyrosine fluorescence spectra, and tryptophan fluorescence thermograms indicate that BSA partially unfolds at ionic surfactant concentrations near and above the CMC. Changes in BSA conformation are less apparent at ionic surfactant concentrations below the CMC and for the nonionic surfactant C12E4. Subtilisin Carlsberg activity against the polypeptide, succinyl‐Ala‐Ala‐Pro‐Phe‐p‐nitroanilide, decreased due to enzyme–surfactant interaction. At the concentrations and time frames studied, there was no enzyme autolysis. Importantly, aqueous proteolysis rates are significantly reduced at high surfactant concentrations where protein–micellar–surfactant aggregates occur. To explain the negative effect of surfactant on subtilisin Carlsberg proteolytic activity against BSA, we propose that micelle/protein complexes hinder enzyme access. Biotechnol. Bioeng. 2009;102: 1330–1341. © 2008 Wiley Periodicals, Inc.
The kinetics of cellulose dissolution in sodium hydroxide solution at low temperatures
Authors: Wang Ying , Deng Yulin 
Published: October 2008

AbstractThe dissolution kinetics of cellulose in sodium hydroxide in the presence and absence of urea at low temperature was studied. High molecular weight cotton linter with degree of polymerization of 850 was used for dissolution study. The cotton linter was separated from the dissolution slurry at different dissolution times, and the change of the crystal structure of cotton linter was characterized by Powder X‐Ray Diffraction. The rate of decrystallization of cellulose was obtained and the activation energy for cellulose decrystallization in sodium hydroxide solution was derived using Eyring equation. The effect of urea additive was discussed. Biotechnol. Bioeng. 2009;102: 1398–1405. © 2008 Wiley Periodicals, Inc.
DBT degradation enhancement by decorating Rhodococcus erythropolis IGST8 with magnetic Fe3O4 nanoparticles
Authors: Ansari F. , Grigoriev P. , Libor S. , Tothill I.E. , Ramsden J.J. 
Published: October 2008

AbstractBiodesulfurization (BDS) of dibenzothiophene (DBT) was carried out by Rhodococcus erythropolis IGST8 decorated with magnetic Fe3O4 nanoparticles, synthesized in‐house by a chemical method, with an average size of 45–50 nm, in order to facilitate the post‐reaction separation of the bacteria from the reaction mixture. Scanning electron microscopy (SEM) showed that the magnetic nanoparticles substantially coated the surfaces of the bacteria. It was found that the decorated cells had a 56% higher DBT desulfurization activity in basic salt medium (BSM) compared to the nondecorated cells. We propose that this is due to permeabilization of the bacterial membrane, facilitating the entry and exit of reactant and product, respectively. Model experiments with black lipid membranes (BLM) demonstrated that the nanoparticles indeed enhance membrane permeability. Biotechnol. Bioeng. 2009;102: 1505–1512. © 2008 Wiley Periodicals, Inc.
Disulfide Bond Creates a Small Connecting Loop in Aminoxy Peptide Backbone
Authors: Yang Dan , Liu Guo‐Jun , Jiao Zhi‐Gang , Zhang Dan‐Wei , Luo Zheng , Song Ke‐Sheng , Chen Min‐Qin 
Published: October 2008

AbstractDisulfide‐bond formation between the side chains of cysteine–cysteine pairs is often critical to the folding behavior, stability, and functionality of proteins. In this paper, we report that sulfur atoms can be introduced into the amide groups of aminoxy peptides to form a novel type of disulfide bridge, which creates a connecting loop in the peptide backbone.
Polymorphic Coordination Networks Responsive to CO2, Moisture, and Thermal Stimuli: Porous Cobalt(II) and Zinc(II) Fluoropyrimidinolates
Authors: Galli Simona , Masciocchi Norberto , Tagliabue Giulia , Sironi Angelo , Navarro Jorge A. R. , Salas Juan M. , Mendez‐Liñan Laura , Domingo Maria , Perez‐Mendoza Manuel , Barea Elisa 
Published: October 2008

AbstractThe novel porous [{M(F‐pymo)2}n]⋅2.5n H2O coordination networks (M=Co, Zn; F‐pymo=5‐fluoropyrimidin‐2‐olate), possessing sodalitic topology, have been synthesised and structurally characterised by means of powder diffraction methods. Thermodiffractometry demonstrated their plasticity: when heated up to 363 K, they reversibly transform into three‐dimensional dehydrated [{M(F‐pymo)2}n] species, with significantly different lattice parameters. Further heating induces irreversible polymorphic transformations into layered phases, in which the original MN4 coordination sphere changes into an MN3O one. A mixed‐metal phase, [{CoxZn1−x(F‐pymo)2}n]⋅2.5n H2O, was also prepared, showing that zinc is preferentially inserted, when starting from a Co/Zn reagent ratio of 1:1. The solid–gas adsorption properties of the anhydrous 3D frameworks have been explored towards N2, H2 (77 K) and CH4, CO2 (273 K). These results show that these materials permit the diffusion of CO2 molecules only. Remarkably, the CO2 adsorption process for the [{Co(F‐pymo)2}n] network proceeds in two steps: the first step takes place at low pressures (<600 kPa) and the second one above a threshold pressure of 600 kPa. By contrast, the [{Zn(F‐pymo)2}n] network only permits CO2 diffusion by applying pressures above 900 kPa. This type of behaviour is typical of porous networks with gated channels. The high CO2 selectivity of these systems over the rest of the essayed probe gases is explained in terms of flexibility and polarity of the porous network. Finally, the magnetic studies on the CoII systems reveal that the as synthesised [{Co(F‐pymo)2}n]⋅2.5n H2O material behaves as an antiferromagnet with a TN of about 29 K. At variance, the [{Co(F‐pymo)2}n] layered phase shows an unusually weak ferromagnetic ordering below 17 K, arising from a spin‐canting phenomenon.
Neuroarchitecture of the central complex of the desert locust: Intrinsic and columnar neurons
Authors: Heinze Stanley , Homberg Uwe 
Published: October 2008

AbstractThe central complex is a group of neuropils in the center of the insect brain. It consists of four major subunits: the upper and lower divisions of the central body (CBU, CBL), the protocerebral bridge (PB), and the paired noduli. A distinctive feature of the central complex is a modular architecture characterized by rows of 16 columns, intersected in the central body by stacks of layers. Evidence from locusts suggests that the central complex plays a major role in sky compass orientation. To understand signal processing in this brain area further, we have analyzed the morphologies of columnar neurons of the central complex of the locust Schistocerca gregaria. Intracellular dye fills revealed 21 types of columnar neurons that connect columns of different subunits, three types of pontine neurons linking pairs of columns within the CBU, and one amacrine cell. Most neurons appeared to be part of isomorphic sets with cell type‐specific heterolateral projection patterns. Evaluation of arborization areas and neuron polarity suggests that these neurons are either intrinsic to the central complex or provide output to the lateral accessory lobes (LALs) or anterior lip region. No direct connections were found between the CBU and CBL. Instead, neurons of either subdivision were connected with the PB, but projected to non‐overlapping regions in the LALs and to different layers of the noduli. This study provides novel insights into the functional organization of the central complex, especially with respect to its likely role in right‐left signal matching and decision making. J. Comp. Neurol. 511:454–478, 2008. © 2008 Wiley‐Liss, Inc.