bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of Dynamic Intra‐ and Intermolecular Processes within a Tether‐Length Dependent Series of Group 4 Bimetallic Initiators for Stereomodulated Degenerative Transfer Living Ziegler–Natta Propene Polymerization
Authors: Zhang Wei , Sita Lawrence R. 
Published: February 2008

AbstractThe series of bimetallic complexes, [(η5‐C5Me5)Zr(Me)2]2 [N(t‐Bu)C(Me)N(CH2)nNC(Me)N(t‐Bu)] 3 (n=8), 4 (n=6), and 5 (n=4) were prepared in high yield through a simple, one‐pot synthesis involving 2 equiv. of in situ generated (η5‐C5Me5)Zr(Me)3 and the corresponding bis‐carbodiimide, (t‐Bu)NCN(CH2)nNCN(t‐Bu). Compounds 3–5 were found to be highly isoselective for the living Ziegler–Natta polymerization of propene upon 100% activation using 2 equiv. of the borate co‐initiator, [PhNHMe2] [B(C6F5)4] (2), with the degree of stereoselectivity decreasing slightly as the two metal centers are brought closer together [cf., 3 (σ=0.92)>4 (σ=0.91)>5 (σ=0.89)]. Under conditions of sub‐stoichiometric activation by 2, all three bimetallic initiators, 3–5, were found to engage in degenerative transfer living Ziegler–Natta polymerization involving rapid and reversible methyl group transfer between active, (cationic) and dormant, (neutral) methyl, polymeryl zirconium centers. Under these conditions, the frequency of mr triad stereoerror incorporation into the polypropene (PP) microstructure decreases as the two metal centers are brought closer together as a result of increasing barriers for metal‐centered epimerization within the neutral metal site due to correspondingly greater non‐bonded steric interactions vis‐à‐vis mononuclear 1.
Novel Palladium‐on‐Carbon/Diphenyl Sulfide Complex for Chemoselective Hydrogenation: Preparation, Characterization, and Application
Authors: Mori Akinori , Mizusaki Tomoteru , Kawase Masami , Maegawa Tomohiro , Monguchi Yasunari , Takao Shinobu , Takagi Yukio , Sajiki Hironao 
Published: February 2008

AbstractA diphenyl sulfide immobilized on palladium‐on‐carbon system, Pd/C[Ph2S], was developed to achieve the highly chemoselective hydrogenation of alkenes, acetylenes, azides, and nitro groups in the presence of aromatic ketones, halides, benzyl esters, and N‐Cbz protective groups. Instrumental analyses of the heterogeneous catalyst demonstrated that diphenyl sulfide was embedded on Pd/C via coordination of its sulfur atom to palladium metal or physical interaction with graphite layers of the activated carbon. The catalyst could be recovered and reused at least five times without any significant loss of the reactivity.
Cooling of spherical particles in a vertical airlift conveyor
Authors: Davies C. E. , Davies R. Y. G. 
Published: February 2008

AbstractThe airlift conveyor modelled here is of a type used in industry to move a particulate feedstock from ground level to an elevated position for gravity feeding to storage or further processing options. It consists of a feed leg and a vertical riser which terminates in a de‐entrainment device where the particles are removed from the conveying gas. Typically the conveying gas enters the riser from a vertical or horizontal feed pipe, and blows the particles off the face of an aerated bed in the horizontal leg of the feeder. The flow rate of the solids is controlled by aeration gas which partially fluidises the material in the feed leg. In this article, we consider the cooling of spherical particles admitted to a conveyor, for a variety of processing conditions. The riser in the model conveyor was 8 m high, the initial particle temperature was 40 °C and the temperature of the conveying air was 20 °C in all calculations. The conveying velocities used were, 12, 15 and 18 m s−1, and the particle sizes were 0.5, 1.0 and 1.5 mm. The particle flow rate was 1 tonne/h. The calculation methodology was to find analytically the slip velocity profile of a single particle over the length of the riser, and then to estimate heat transfer rates numerically using a Microsoft Office Excel spreadsheet. Temperature profiles show that for all conditions examined, over 70–80% of heat transfer takes place in the first half of the riser. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.
Synthesis and characterization of nylon 6/clay nanocomposites prepared by ultrasonication and in situ polymerization
Authors: McAdam C. P. , Hudson N. E. , Liggat J. J. , Pethrick R. A. 
Published: February 2008

AbstractNylon 6 nanocomposites were prepared by the in situ polymerization of ε‐caprolactam with ultrasonically dispersed organically modified montmorillonite clay (Cloisite 30B®). Dispersions of the clay platelets with concentrations in the range 1–5 wt % in the monomer were characterized using rheological measurements. All mixtures exhibited shear‐thinning, signifying that the clay particles were dispersed as platelets and forming a “house of cards” structure. Samples with Cloisite concentrations above 2 wt % showed a drop in viscosity between the initial shearing and repeated shearing, indicative of shearing breaking down the initial “house of cards” structures formed on sonication. DMTA measurements of the samples showed an increase in the β‐relaxation temperature with increasing clay concentration. The bending modulus, at temperatures below Tg, showed an increase with increasing clay concentration up to 4 wt %. X‐ray diffraction measurements showed that all nylon 6/Cloisite 30B samples were exfoliated apart from the 5 wt %, which showed that some intercalated material was present. The nylon crystallized into the α‐crystalline phase, which is the most thermodynamically stable form. Preference for this form may be a consequence of the long time associated with the postcondensation step in the synthesis or the influence of the platelets on the nucleation step of the crystal growth. DSC measurements showed a retardation of the crystallization rate of nanocomposite samples when compared with that of pure nylon 6, due to the exfoliated clay platelets hindering chain movement. This behavior is different from that observed for the melt‐mixed nylon 6/clay nanocomposites, which show an enhancement in the crystallization rate. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Preparation and physical properties of nonionic aqueous polyurethane coatings containing different side chain PEGME length
Authors: Tsai Hsiang‐Chin , Hong Po‐Da , Yen Meng‐Shung 
Published: February 2008

AbstractNonionic aqueous polyurethane (NAPU) coatings were prepared by a prepolymer process using 4,4‐methylene bis(isocyanatocyclohexane), poly(tetramethylene glycol) with a molecular weight of 2000 g/mol (PTMG2000), ethylenediamine and a synthesized nonionic dispersing centers of various molecular weight produced by isophorone diisocyanate, N‐diethanol amine, and poly(ethylene glycol) monomethyl ether (PEGME) with different molecular weights. The dispersion properties of the NAPU emulsions, thermal properties of the NAPU casting films, and its tensile strength were studied. Further, the water vapor permeability (WVP) and waterproof of NAPU‐coated fabric were also examined. Our results showed that the surface tension and particle size of NAPU emulsion increase with the decrease in PEGME chain length. For the thermal properties, the melting point of soft‐segment of NAPU casting films was not affected by the PEGME chain length, but the heat of fusion of the soft‐segment was greatly affected. In particular, the NAPU with PEGME chain length of 2000 g/mol has two obviously crystalline endothermic peaks. The lower peak was attributed to crystallizing PTMG2000. The higher peak was attributed to the crystallizing side chain PEGME of Mw = 2000 g/mol. The WVP followed the order: NAPU with PEGME chain length 750 g/mol > 550 g/mol > 350 g/mol > 2000 g/mol, and the waterproof increases with increase in PEGME length. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008
Influence of adhesion to activated carbon particles on the viability of waterborne pathogenic bacteria under flow
Authors: van der Mei Henny C. , Atema‐Smit Jelly , Jager Debbie , Langworthy Don E. , Collias Dimitris I. , Mitchell Michael D. , Busscher Henk J. 
Published: February 2008

AbstractIn rural areas around the world, people often rely on water filtration plants using activated carbon particles for safe water supply. Depending on the carbon surface, adhering microorganisms die or grow to form a biofilm. Assays to assess the efficacy of activated carbons in bacterial removal do not allow direct observation of bacterial adhesion and the determination of viability. Here we propose to use a parallel plate flow chamber with carbon particles attached to the bottom plate to study bacterial adhesion to individual carbon particles and determine the viability of adhering bacteria. Observation and enumeration is done after live/dead staining in a confocal laser scanning microscope. Escherichiae coli adhered in higher numbers than Raoultella terrigena, except to a coconut‐based carbon, which showed low bacterial adhesion compared to other wood‐based carbon types. After adhesion, 83–96% of the bacteria adhering to an acidic carbon were dead, while on a basic carbon 54–56% were dead. A positively charged, basic carbon yielded 76–78% bacteria dead, while on a negatively charged coconut‐based carbon only 32–37% were killed upon adhesion. The possibility to determine both adhesion as well as the viability of adhering bacteria upon adhesion to carbon particles is most relevant, because if bacteria adhere but remain viable, this still puts the water treatment system at risk, as live bacteria can grow and form a biofilm that can then be shedded to cause contamination. Biotechnol. Bioeng. 2008;100: 810–813. © 2008 Wiley Periodicals, Inc.
Proton transport inside the biofilm limits electrical current generation by anode‐respiring bacteria
Authors: Torres César I. , Kato Marcus Andrew , Rittmann Bruce E. 
Published: February 2008

AbstractAnode‐respiring bacteria (ARB) in a biofilm anode carry out an oxidation half‐reaction of organic matter, producing an electrical current from renewable biomass, including wastes. At the same time, ARB produce protons, usually one proton for every electron. Our study shows how current density generated by an acclimated ARB biofilm was limited by proton transport out of the biofilm. We determined that, at high current densities, protons were mainly transported out of the biofilm by protonating the conjugate base of the buffer system; the maximum current generation was directly related to the transport of the buffer, mainly by diffusion, into and out of the biofilm. With non‐limiting acetate concentrations, the current density increased with higher buffer concentrations, going from 2.21 ± 0.02 A m−2 with 12.5‐mM phosphate buffer medium to 9.3 ± 0.4 A m−2 using a 100‐mM phosphate buffer at a constant anode potential of Eanode = −0.35 V versus Ag/AgCl. Increasing the concentration of sodium chloride in the medium (0–100 mM) increased current density by only 15%, indicating that ion migration was not as important as diffusion of phosphate inside the biofilm. The current density also varied strongly with medium pH as a result of the buffer speciation: The current density was 10.0 ± 0.8 A m−2 at pH 8, and the pH giving one‐half the maximum rate was 6.5. A j–V curve analysis using 100 mM phosphate buffer showed a maximum current density of 11.5 ± 0.9 A m−2 and half‐saturation potential of −0.414 V versus Ag/AgCl, a value that deviated only slightly from the standard acetate potential, resulting in small anode‐potential losses. We discuss the implications of the proton‐transport limitation in the field of microbial fuel cells and microbial electrolytic cells. Biotechnol. Bioeng. 2008;100: 872–881. © 2008 Wiley Periodicals, Inc.
Protopanaxadiol 6‐hydroxylase and its role in regulating the ginsenoside heterogeneity in Panax notoginseng cells
Authors: Yue Cai‐Jun , Zhou Xin , Zhong Jian‐Jiang 
Published: February 2008

AbstractVarious structure‐similar plant secondary metabolites like ginseng saponins (ginsenosides) possess different or even totally opposite biological activities. Intentional manipulation of the ginsenoside heterogeneity in cellular biosynthesis is of great interest and significance [Zhong and Yue (2005); Adv Biochem Eng Biotechnol 100:53–88]. In this work, CO‐binding spectra of microsomes prepared from the suspended cells of Panax notoginseng showed increases in absorption at 450 nm compared with the control without CO sparging, and protopanaxadiol 6‐hydroxylase (P6H), a new enzyme catalyzing the conversion of ginsenoside aglycone protopanaxadiol into protopanaxatriol, was found. P6H was dependent on NADPH and molecular oxygen. The enzymatic reaction was inhibited by carbon monoxide and partially reversible upon illumination with blue light, and sensitive to cytochrome P450 inhibitors. The results supported the contention that P6H was a cytochrome P450‐dependent hydroxylase, whose catalytic product was confirmed to be protopanaxatriol by HPLC‐MS. Induction of P6H activity by phenobarbital, a cytochrome P450 inducer, was observed. A maximal activity of P6H was obtained with addition of 0.5 mM phenobarbital on day 4 of shake‐flask cultivation. The maximum content of protopanaxatriol‐type ginsenosides (Rg1 and Re, Rg group) and the maximum ratio of the content of protopanaxatriol: protopanaxadiol reached 6.88 ± 0.21 mg g−1 dry weight and 7.0, respectively, which was about 1.4 and 2.0‐fold that of respective controls (without addition of phenobarbital). Oxidative burst was also observed in the cell cultures with addition of phenobarbital. P6H was concluded as a key enzyme in regulating Rg‐group ginsenoside biosynthesis in P. notoginseng cells. Biotechnol. Bioeng. 2008;100: 933–940. © 2008 Wiley Periodicals, Inc.
Electronic problem based learning of electromagnetics through software development
Authors: Mias Christos 
Published: February 2008

AbstractA computer‐assisted problem‐based learning (PBL) project is proposed to assist undergraduate student learning of electromagnetics through software development. The project employs the finite difference time domain (FDTD) method to model transmission line performance. The usefulness of this approach is evaluated from direct observation and formative assessment. © 2008 Wiley Periodicals, Inc. Comput Appl Eng Educ 16: 12–20, 2008; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20112
A framework for exercises in computer science
Authors: Fjeldaas Sven 
Published: February 2008

AbstractThis text describes a laboratory course in practical handling of computers, a computer network, and a C++ compiler. Most of the software used is running under the Linux operating system. Some aspects of file and directory structures, revision control, maintenance and backup solutions for hardware, software and instruction material, are discussed. It is suggested that an introductory course of the type described and a geometric modeler make a rich environment, suitable as a basis and a framework for hands‐on exercises in computer science. Applications in other courses are indicated. © 2008 Wiley Periodicals, Inc. Comput Appl Eng Educ 16: 55–61, 2008; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20118
Exchange Rate Constants of Invisible Protons in Proteins Determined by NMR Spectroscopy
Authors: Segawa Takuya , Kateb Fatiha , Duma Luminita , Bodenhausen Geoffrey , Pelupessy Philippe 
Published: February 2008

AbstractAlthough labile protons that are exchanging rapidly with those of the solvent cannot be observed directly, their exchange rate constants can be determined by indirect detection of scalar‐coupled neighboring nuclei. We have used heteronuclear NMR spectroscopy to measure the exchange rate constants of labile protons in the side chains of lysine and arginine residues in ubiquitin enriched in carbon‐13 and nitrogen‐15 at neutral pH. Exchange rate constants as fast as 40×103 s−1 were thus measured. These results demonstrate that NMR spectroscopy is a powerful tool for the characterization of lysine NH3+ and arginine NH groups in proteins at physiologically relevant pH values.
Development of Pyrrolo[2,1‐c][1,4]benzodiazepine β‐Galactoside Prodrugs for Selective Therapy of Cancer by ADEPT and PMT
Authors: Kamal Ahmed , Tekumalla Venkatesh , Krishnan Anita , Pal‐Bhadra Manika , Bhadra Utpal 
Published: February 2008

AbstractThe pyrrolo[2,1‐c][1,4]benzodiazepines (PBDs) are a class of well‐studied DNA‐interactive agents with a potential for use in the treatment of cancer. The clinical utility of these molecules is limited because of the lack of selectivity for tumor tissues, high reactivity of the pharmacophoric imine functionality, low water solubility, and stability. To address the shortcomings, especially the lack of selectivity, associated with the molecules, two new β‐galactoside prodrugs of PBDs have been synthesized and evaluated for their potential use in selective therapy of solid tumors by ADEPT and PMT protocols. The preliminary studies reveal the prodrugs to be much less toxic compared to the parent moieties. These prodrugs are activated by E. coli β‐galactosidase (EC 3.2.1.23) to form the active cytotoxic moiety signifying their utility in ADEPT of cancer. One of the significant outcomes of the present study is the toxification of the prodrug 1 a by the endogenous β‐galactosidase of human liver cancer cells (Hep G2) to form the cytotoxic moiety, enabling selective therapy of hepatocellular carcinoma. Another important property of these molecules is their enhanced water solubility and stability, which are essential for a molecule to be an effective drug.
Thalamic projections to the posteromedial cortex in the macaque
Authors: Buckwalter Joseph A. , Parvizi Josef , Morecraft Robert J. , van Hoesen Gary W. 
Published: February 2008

AbstractThe medial parietal, posterior cingulate, and retrosplenial cortices collectively constitute a region of cortex referred to as the posteromedial cortices (PMC). In an effort to shed light on the neuroanatomical organization of the PMC, we undertook a study to identify and analyze the thalamocortical connections of these cortices. Retrograde tracer injections were placed in the posterior cingulate (PCC), retrosplenial (RSC), medial parietal cortices (MPC), and posterior cingulate sulcus (PCS), and the labeling patterns within the thalamus were analyzed. Three afferent projection patterns were observed to the PMC from the thalamus: a PCC/RSC pattern that involved the anterior thalamic nuclei, an MPC pattern that involved the lateral posterior and pulvinar nuclei, and a PCS pattern that involved the ventral thalamic nuclei. Additionally, a shared pattern of projections from the anterior intralaminar nuclei (AILN) and posterior thalamic nuclei (PTN) to all cortical regions of the PMC was observed. Our findings suggest that distinct regions within the PMC are supplied by distinctive patterns of thalamic input, but also share common projections from intralaminar and posterior thalamic sources. In addition, we relate our findings to functional abnormalities in aging and dementia, and address a domain‐like pattern of thalamocortical labeling of the PMC that is drawn selectively and collectively from multiple thalamic nuclei. J. Comp. Neurol. 507:1709–1733, 2008. © 2008 Wiley‐Liss, Inc.
cpg15 and cpg15‐2 constitute a family of activity‐regulated ligands expressed differentially in the nervous system to promote neurite growth and neuronal survival
Authors: Fujino Tadahiro , Wu Zhen , Lin Walter C. , Phillips Marnie A. , Nedivi Elly 
Published: February 2008

AbstractMany ligands that affect nervous system development are members of gene families that function together to coordinate the assembly of complex neural circuits. cpg15/neuritin encodes an extracellular ligand that promotes neurite growth, neuronal survival, and synaptic maturation. Here we identify cpg15‐2 as the only paralogue of cpg15 in the mouse and human genome. Both genes are expressed predominantly in the nervous system, where their expression is regulated by activity. cpg15‐2 expression increases by more than twofold in response to kainate‐induced seizures and nearly fourfold in the visual cortex in response to 24 hours of light exposure following dark adaptation. cpg15 and cpg15‐2 diverge in their spatial and temporal expression profiles. cpg15‐2 mRNA is most abundant in the retina and the olfactory bulb, as opposed to the cerebral cortex and the hippocampus for cpg15. In the retina, they differ in their cell‐type specificity. cpg15 is expressed in retinal ganglion cells, whereas cpg15‐2 is predominantly in bipolar cells. Developmentally, onset of cpg15‐2 expression is delayed compared with cpg15 expression. CPG15‐2 is glycosylphosphatidylinositol (GPI) anchored to the cell membrane and, like CPG15, can be released in a soluble‐secreted form, but with lower efficiency. CPG15 and CPG15‐2 were found to form homodimers and heterodimers with each other. In hippocampal explants and dissociated cultures, CPG15 and CPG15‐2 promote neurite growth and neuronal survival with similar efficacy. Our findings suggest that CPG15 and CPG15‐2 perform similar cellular functions but may play distinct roles in vivo through their cell‐type‐ and tissue‐specific transcriptional regulation. J. Comp. Neurol. 507:1831–1845, 2008. © 2008 Wiley‐Liss, Inc.
Job submission to grid computing environments
Authors: Bruin R. P. , White T. O. H. , Walker A. M. , Austen K. F. , Dove M. T. , Tyer R. P. , Couch P. A. , Todorov I. T. , Blanchard M. O. 
Published: February 2008

AbstractThe problem of enabling scientist users to submit jobs to grid computing environments will eventually limit the usability of grids. The eMinerals project has tackled this problem by developing the ‘my_condor_submit’ (MCS) tool, which provides a simple scriptable interface to Globus, a flexible interaction with the storage resource broker, metascheduling with load balancing within a grid environment, and automatic metadata harvesting. This paper provides an overview of MCS together with a use case. We also describe the use of MCS within parameter‐sweep studies. Copyright © 2008 John Wiley & Sons, Ltd.
Formation of Organobrominated Compounds in the Presence of Bromide under Simulated Atmospheric Aerosol Conditions
Authors: Vione Davide , Maurino Valter , Man Simona Cucu , Khanra Swapan , Arsene Cecilia , Olariu Romeo‐Iulian , Minero Claudio 
Published: February 2008

AbstractPhotobromination of phenol takes place upon UV/Vis irradiation of FeIII and bromide under acidic conditions, and most likely involves the brominating agent Br2−.. Bromination is also observed in the presence of nitrate and bromide under UV irradiation, most likely involving Br2−. formed upon oxidation of bromide by .OH. Moreover, quantitative bromination of phenol is observed in the dark in the presence of hydrogen peroxide and bromide. This process is strongly favored under acidic conditions, but a residual, pH‐independent bromination pathway is also present. The rates and yields of bromination (up to 100 %) are considerably higher than those reported for chlorination under comparable conditions, suggesting that the higher activity of bromine species could compensate for the lower concentration of bromide ions in aerosol compared to chlorides. The reported processes are potential sources of reactive bromine species (Br2−., HBrO) and aromatic bromo derivatives in atmospheric aerosols, in particular after the acidification process linked with aerosol aging.