bluuebunny/crossref_metadata_2025_split huggingface dataset:
A parsimonious combination of functional traits predicting plant response to disturbance and soil fertility
Authors: Kühner Anke , Kleyer Michael 
Published: April 2008

AbstractQuestions:1. How many traits associated with persistence and regeneration are necessary to predict the response of plants to soil fertility and disturbance? 2. Are correlated changes in trait expressions linked to the response of functional groups to fertility and disturbance?Location:Lower Frankonia, Germany.Methods:On 120 plots located in managed and abandoned grasslands, fields, and vineyards, we recorded species composition, disturbance intensity, soil water and nutrients, and ten candidate traits for 75 species. We used a novel method which is based on three steps: (1) logistic regression to separate responsive from non‐responsive species; (2) iterative clustering of all possible combinations of the candidate traits including regression of each cluster in response to the environmental variables; (3) selection of the trait combination that performed best with respect to goodness of fit of all clusters from this combination. Bivariate trait relationships across functional groups were analysed with reduced major axis regression (RMA).Results:The parsimonious trait combination consisted of life span, specific leaf area (SLA), canopy height, and seed number. The ‘acquisitive’functional groups in terms of SLA and height were linked to higher fertility and earlier disturbance, while the ‘retentive’groups related to lower fertility and later disturbance. Investment in reproduction, however, displayed a reverse relation. SLA and canopy height showed correlated shifts in two pairs of co‐occurring functional groups.Conclusions:A small number of traits is sufficient to predict the response of species. Plants need a higher increment in SLA to reach the same height, if start of disturbance is earlier. Linkages between traits shift from generative to vegetative with increasing fertility and earlier start of disturbance. Functional groups enable shifts in scaling relationships between traits to be analysed, in contrast to the analysis of single traits.
Asymmetric Hydrogenation of Quinolines Catalyzed by Iridium Complexes of Monodentate BINOL‐Derived Phosphoramidites
Authors: Mršić Nataša , Lefort Laurent , Boogers Jeroen A. F. , Minnaard Adriaan J. , Feringa Ben L. , de Vries Johannes G. 
Published: April 2008

AbstractThe monodentate BINOL‐derived phosphoramidite PipPhos is used as ligand for the iridium‐catalyzed asymmetric hydrogenation of 2‐ and 2,6‐substituted quinolines. If tri‐ortho‐tolylphosphine and/or chloride salts are used as additives enantioselectivities are strongly enhanced up to 89%. NMR indicates that no mixed complexes are formed upon addition of tri‐ortho‐tolylphosphine.
Inclusions of amyotrophic lateral sclerosis–linked superoxide dismutase in ventral horns, liver, and kidney
Authors: Jonsson P. Andreas , Bergemalm Daniel , Andersen Peter M. , Gredal Ole , Brännström Thomas , Marklund Stefan L. 
Published: April 2008

AbstractMutant superoxide dismutases type 1 (SOD1s) cause amyotrophic lateral sclerosis by an unidentified toxic property. In a patient carrying the G127X truncation mutation, minute amounts of SOD1 were found in ventral horns using a mutant‐specific antibody. Still, both absolute levels and ratios versus wild‐type SOD1 were considerably greater than in other central nervous system areas and peripheral organs. Inclusions of mutant SOD1 were abundant in motoneurons but were also seen in hepatocytes and kidney epithelium. This first examination of mutant SOD1 in both central nervous system and peripheral organs supports the notion that enrichment of misfolded SOD1s might explain the particular vulnerability of motor areas. Ann Neurol 2008
Body mass index and magnetic resonance markers of brain integrity in adults
Authors: Gazdzinski Stefan , Kornak John , Weiner Michael W. , Meyerhoff Dieter J. 
Published: April 2008

AbstractObjectiveObesity and being overweight during adulthood have been consistently linked to increased risk for development of dementia later in life, especially Alzheimer's disease. They have also been associated with cognitive dysfunction and brain structural alterations in otherwise healthy adults. Although proton magnetic resonance spectroscopy may distinguish between neuronal and glial components of the brain and may point to neurobiological mechanisms underlying brain atrophy and cognitive changes, no spectroscopic studies have yet assessed the relationships between adiposity and brain metabolites.MethodsWe have utilized magnetic resonance imaging and proton magnetic resonance spectroscopic imaging data from 50 healthy middle‐aged participants (mean age, 41.7 ± 8.5 years; 17 women), who were scanned as control subjects for another study.ResultsAfter adjustment for age and sex, greater body mass indices (BMIs) correlated with: (1) lower concentrations of N‐acetylaspartate (spectroscopic marker of neuronal viability) in frontal (p = 0.001), parietal (p = 0.006), and temporal (p = 0.008) white matter; (2) lower N‐acetylaspartate in frontal gray matter (p = 0.01); and (3) lower concentrations of choline‐containing metabolites (associated with membrane metabolism) in frontal white matter (p = 0.05).InterpretationThese results suggest that increased BMI at midlife is associated with neuronal and/or myelin abnormalities, primarily in the frontal lobe. Because white matter in the frontal lobes is more prone to the effects of aging than in other lobes, our results may reflect accelerated aging in individuals with high levels of adiposity. Thus, greater BMI may increase the odds of developing an age‐related disease, such as Alzheimer's disease. Ann Neurol 2008
Electrospun nanofibers from crosslinked poly(vinyl alcohol) and its filtration efficiency
Authors: Qin Xiao‐Hong , Wang Shan‐Yuan 
Published: April 2008

AbstractNanoscaled crosslinked poly(vinyl alcohol) PVA fibers were prepared by electrospinning. This study described its electrospinning process, structure, and filtration applications. The fibers were found to be efficiently crosslinked by maleic acid. Vitriolic acid was used as a catalyst activator during crosslinking. Scanning electron micrograph and differential scanning calorimetric techniques as well as infrared reflection–absorption spectroscopy (FTIR) were employed to characterize the morphology and structure of crosslinking of PVA fibers, PVA fibers as well as PVA powder. Moreover, the filtration properties of crosslinked PVA nanofibers were tested. During the experiments, crosslinked PVA nanofibers layers with different area weight were placed on the spunbond or meltblown sublayers. The result shows that the filtration efficiency increases sharply when crosslinked PVA nanofibers layers were added to the sublayers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Studies of influence of naphthalene mono/disulfonic acid dopant on thermal stability of polypyrrole
Authors: Liu Jing , Wang Xiaocong , Hu Xiangzheng , Xiao Anqinq , Wan Meixiang 
Published: April 2008

AbstractThermal stability of polypyrrole (PPY) synthesized by in situ doping polymerization in the presence of different naphthalene mono/disulfonic acid dopant like α‐naphthalene sulfonic acid (α‐NSA), β‐naphthalene sulfonic acid (β‐NSA), and 1,5‐naphthalene disulfonic acid (1,5‐NDSA) has been systematically investigated by thermogravimetric analysis (TG). It was found that the thermal stability of as‐resulted PPY was greatly affected by type and concentration of dopant. In general, the order of their thermal stability was PPY‐(β‐NSA) > PPY‐(α‐NSA) ≈ PPY‐(1,5‐NDSA). And high concentration of dopant (e.g., 1.2 mol/L) had a negative effect on the thermal stability. Among those three dopants, 1,5‐NDSA had a unique influence on thermal stability and crystallinity of as‐resulted PPY. In addition, all of room‐temperature conductivity and crystallinity of PPY‐(1,5‐NDSA) changed dramatically after aging for 9 h under N2 atmosphere and at 230°C, which may be due to a partly dedoping process. These results were confirmed by elemental analysis, FTIR, X‐ray photoelectron spectroscopy (XPS), and X‐ray powder diffraction (XRD). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Rheological behavior of a microcellular, oil‐extended ethylene–propylene–diene rubber compound: Effects of the blowing agent curing agent, and conductive carbon black filler
Authors: Mahapatra S. P. , Tripathy D. K. 
Published: April 2008

AbstractThe rheological behavior of microcellular, oil‐extended ethylene–propylene–diene rubber (EPDM) compounds was studied in extrusions containing a blowing agent. The cell morphology development and rheological properties were studied for unfilled and conductive carbon black (Vulcan XC72, Cabot Corp., Ltd., Alpharetta, GA) filled compounds with variations of the blowing agent, extrusion temperature, and shear rate. The apparent shear stress, apparent viscosity, die swell (%), and total extrusion pressure of the Vulcan XC72 filled, oil‐extended EPDM compounds were determined with a Monsanto processability tester (St. Louis, MO). The effects of the curing agent and blowing agent on the rheological properties of the compounds were also studied. A significant reduction in the stress and viscosity with the blowing agent was observed in the compound in the presence of the curing agent in comparison with those without the curing agent. The viscosity reduction factor was found to be dependent on the blowing agent loading, shear rate, and temperature. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Copolymerization of methyl methacrylate with N‐(methoxyphenyl) itaconimides
Authors: Chauhan Rashmi , Choudhary Veena 
Published: April 2008

AbstractThis article describes the synthesis and characterization of N‐(3‐methoxyphenyl) itaconimide (MAI) and N‐(4‐methoxyphenyl) itaconimide (PAI) obtained by the reaction of itaconic anhydride with m‐anisidine and p‐anisidine, respectively. Structural and thermal characterization of MAI and PAI monomers was performed with Fourier transform infrared (FTIR), 1H‐NMR, differential scanning calorimetry (DSC), and thermogravimetric analysis. Copolymerization of methyl methacrylate (MMA) with various amounts of MAI or PAI ranging from 0.1 to 0.5 was performed in solution with azobisisobutyronitrile as an initiator. Structural and molecular characterization of copolymers was performed with FTIR, 1H‐NMR, elemental analysis, and gel permeation chromatography. The nitrogen percentage was used to calculate the copolymer composition. The monomer reactivity ratios for MMA–MAI copolymers were found to be 1.00 ± 0.01 for MMA and 0.99 ± 0.07 for MAI; those for MMA–PAI copolymers were 0.93 ± 0.02 for MMA and 1.11 ± 0.10 for PAI. The molecular weights of the copolymers were in the range of 0.94–9.7 × 103 (number‐average molecular weight) and 3.3–101.8 × 103 (weight‐average molecular weight), with polydispersity indices in the range of 1.5–4.1. The molecular weight decreased with the increasing molar fraction of imide in the polymer backbone. The glass‐transition temperature, as determined from DSC scans, increased with increasing amounts of itaconimides in the copolymers. A significant improvement in the char yield, as determined by thermogravimetry, was observed upon copolymerization. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Influence of the diene monomer on devulcanization of EPDM rubber
Authors: Verbruggen M. A. L. , van der Does L. , Noordermeer J. W. M. , van Duin M. 
Published: April 2008

AbstractEthylene–propylene–diene rubbers (EPDM) with 2‐ethylidene‐5‐norbornene (ENB), dicyclopentadiene (DCPD), and 1,4‐hexadiene (HD) as third monomers have been vulcanized with peroxide and with a conventional sulfur vulcanization recipe, and their devulcanization was subsequently investigated for recycling purposes. The behavior of these vulcanizates during pure thermal devulcanization depends on the EPDM third monomer and the crosslinker used. Peroxide vulcanizates of ENB‐EPDM devulcanize only to a small extent and predominantly by random scission, whereas peroxide vulcanizates of HD‐EPDM devulcanize by crosslink scission. In contrast, sulfur vulcanizates of ENB‐EPDM, devulcanize mainly by crosslink scission. During devulcanization of sulfur‐cured HD‐EPDM, scission of both crosslinks and main chains occurs. Sulfur‐cured DCPD‐EPDM cannot be devulcanized but shows further crosslinking instead. In those cases, where purely thermal devulcanization is already effective to a certain extent, diphenyldisulfide as devulcanization agent increases the effectivity during thermochemical devulcanization. Hexadecylamine as an alternative devulcanization agent is effective for ENB‐EPDM but does not contribute to thermochemical devulcanization of HD‐EPDM. In summary, devulcanization proceeds by different mechanisms in ENB‐EPDM, DCPD‐EPDM, and HD‐EPDM. Explanations are given in terms of the chemical structures of the third monomers, the corresponding crosslinks, and devulcanization agents. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Antimicrobial finishing of regular and modified polyethylene terephthalate fabrics
Authors: Shalaby S. E. , Al‐Balakocy N. G. , Beliakova M. K. , Abdel‐Fatah O. M. , Elshafei A. M. 
Published: April 2008

AbstractAn effective two‐stage method has been developed for imparting antimicrobial properties to regular polyethylene terephthalate (R‐PET), polyethylene glycol modified polyethylene terephthalate (PEG‐M‐PET), R‐PET/Cotton blend (R‐PET/C) and PEG‐M‐PET/Cotton blend (PEG‐M‐PET/C) fabrics. The method consists of partial hydrolysis of the fabrics to create carboxylic groups in PET macromolecules followed by subsequent reaction with dimethylalkylbenzyl ammonium chloride (DMABAC) under alkaline conditions. The reaction conditions such as pH, reaction temperature and time, carboxylic content, and DMABAC concentration were studied. Characterization of the finished fabrics was carried out through scanning electron microscopy (SEM) and Fourier transform infrared spectra (FTIR). All the modified PET fabrics showed excellent antibacterial activity towards Gram‐positive (Bacillus mycoides), Gram‐negative (Escherichia coli), and nonfilamentous fungus (Candida albicans). The achieved antimicrobial functions on the PET fabrics are durable in repeated laundering processes. Even after laundering 10 times the fabrics could still provide more than 85% of its antimicrobial activity against B. mycoides, E. coli, and C. albicans. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Synthesis and Biological Activity of Functionalized Indole‐2‐carboxylates, Triazino‐ and Pyridazino‐indoles
Authors: El‐Gendy Adel A. , Said Mohamed M. , Ghareb Nagat , Mostafa Yasser M. , El‐Ashry El Sayed H. 
Published: April 2008

AbstractCondensation of aryl hydrazines with ethyl pyruvate gave the respective hydrazones 4–6; Fischer indolization led to substituted‐1H‐indole‐2‐carboxylic acid ethyl esters 7–9. The Mannich reaction of these compounds with formaldehyde and morpholine yielded ethyl 3‐(morpholinomethyl)‐substituted‐1H‐indole‐2‐carboxylates 10‐12. The 5,7‐dichloro‐1H‐indole‐2‐carbohydrazide 13 was cyclized with methyl orthoformate in DMF to give 6,8‐dichloro[1,2,4]triazino[4,5‐a]indol‐1(2H)‐one 14. Vilsmeier–Haack formylation of 7–9 gave ethyl 3‐formyl‐substituted‐1H‐indole‐2‐carboxylates 15–17 whose 2,2′‐((5‐chloro‐2‐(ethoxycarbonyl)‐1H‐indol‐3‐yl)methylene)bis‐(sulfanediyl) diacetic acid 18 was prepared. The reaction of 15 and 16 with substituted anilines by conventional and microwave methods gave ethyl 3‐(N‐aryliminomethyl)‐5‐halo‐1H‐indole‐2‐carboxylates 19–29. In a cyclocondensation reaction of 19–25 with thiolactic acid or thioglycolic acid substituted indolylthiazolidinones 30–33 were prepared. Reaction of hydrazine hydrate with 15–17 did not give the respective hydrazones but directly led to the cyclized products substituted‐3H‐pyridazino[4,5‐b]indol‐4(5H)‐ones 34–36, while a reaction with 2,4‐dichlorophenylhydrazine yielded the uncyclized hydrazones. The chlorination of 35 and 36 with POCl3 gave pyridazino[4,5‐b]indoles 39 and 40, respectively; reaction of the latter compounds with morpholine gave 4‐(substituted‐5H‐pyridazino[4,5‐b]indol‐4‐yl)morpholine 41 and 42. Mannich reaction of 34 with formaldehyde and N‐ethylpiperazine gave 8‐chloro‐3‐((4‐ethylpiperazin‐1‐yl)methyl)‐3H‐pyridazino[4,5‐b]indol‐4(5H)‐one 43. The microwave assistance of selected reactions has a profound effect on the reaction speed. The structures of the new compounds were confirmed by both analytical and spectral data. Some compounds were subjected to investigations concerning their antimicrobial, tranquilizing, and anticonvulsant activities.
Analysis of the Tetronomycin Gene Cluster: Insights into the Biosynthesis of a Polyether Tetronate Antibiotic
Authors: Demydchuk Yuliya , Sun Yuhui , Hong Hui , Staunton James , Spencer Jonathan B. , Leadlay Peter F. 
Published: April 2008

AbstractThe biosynthetic gene cluster for tetronomycin (TMN), a polyether ionophoric antibiotic that contains four different types of ring, including the distinctive tetronic acid moiety, has been cloned from Streptomyces sp. NRRL11266. The sequenced tmn locus (113 234 bp) contains six modular polyketide synthase (PKS) genes and a further 27 open‐reading frames. Based on sequence comparison to related biosynthetic gene clusters, the majority of these can be assigned a plausible role in TMN biosynthesis. The identity of the cluster, and the requirement for a number of individual genes, especially those hypothesised to contribute a glycerate unit to the formation of the tetronate ring, were confirmed by specific gene disruption. However, two large genes that are predicted to encode together a multifunctional PKS of a highly unusual type seem not to be involved in this pathway since deletion of one of them did not alter tetronomycin production. Unlike previously characterised polyether PKS systems, oxidative cyclisation appears to take place on the modular PKS rather than after transfer to a separate carrier protein, while tetronate ring formation and concomitant chain release share common mechanistic features with spirotetronate biosynthesis.
Redilation of e‐PTFE covered CP stents
Authors: Butera Gianfranco , Gaio Gianpiero , Carminati Mario 
Published: April 2008

AbstractObjectives: To evaluate the possibility to redilate covered Cheatham‐Platinum stents during follow‐up, in particular in growing children with aortic coarctation. Background: There are no data in the literature about the redilation of ePTFE covered CP stents. Methods: Sixty covered CP stents were implanted in patients with aortic coarctation or recoarctation between January 2004 and October 2007. Seven patients (mean age 14.2 ± 3.7 years) needed to repeat the hemodynamic study due to somatic growth and increase of aortic gradient with the occurrence of systemic hypertension. Two had near‐atretic aortic coarctation, three had postsurgical recoarctation and aneurysm formation, one had native aortic coarctation associated with aneurysm of the arterial wall, and one had severe native aortic coarctation. Results: Procedures were performed a mean of 20 ± 5 months (range, 12–24 months) after the primary stent implantation. Fluoroscopy time ranged between 7 and 15 min (median, 10 min) whereas procedure time ranged between 60 and 75 min (median, 65 min). After redilation the gradient across the stenosis decreased from a median value of 35 mm Hg to a median value of 5 mm Hg. The stent diameter increased of 20–50% the predilation value. No complications occurred and angiographic controls showed that the stenoses have been relieved. Follow‐up: During a median follow‐up of 12 months (6–30 months) the results were stable without complications. Conclusion: Covered Cheatham‐Platinum stents can be easily redilated © 2008 Wiley‐Liss, Inc.
Effects of Peripheral Chloro Substitution on the Photophysical Properties and in vitro Photodynamic Activities of Galactose‐Conjugated Silicon(IV) Phthalocyanines
Authors: Lo Pui‐Chi , Fong Wing‐Ping , Ng Dennis K. P. 
Published: April 2008

AbstractA series of silicon(IV) phthalocyanines with two axial isopropylidene‐protected galactose moieties and one, two, or eight chloro group(s) on the periphery of the macrocycle have been synthesised and spectroscopically characterised. The photophysical properties and in vitro photodynamic activities of these compounds have been studied and compared with those of the nonchlorinated analogue. All the compounds, with the exception of the octachlorinated counterpart which has a limited solubility, are essentially nonaggregated in N,N‐dimethylformamide. The fluorescence quantum yield decreases and the singlet oxygen quantum yield increases as the number of chloro substituent increases, which is in accord with the heavy‐atom effect. The non‐, mono‐, and dichlorinated phthalocyanines formulated with Cremophor EL are all photodynamically active against HT29 human colon adenocarcinoma and HepG2 human hepatocarcinoma cells with IC50 values ranging from 0.03 to 1.05 μM. The photocytotoxicity as well as the efficiency to generate intracellular reactive oxygen species decrease along this series because of the increase in aggregation tendency upon chloro substitution. The nonchlorinated analogue exhibits the highest potency and can target the lysosomes of HT29 cells, whereas the monochlorinated counterpart is not localised in the lysosomes.
Stable Non‐IPR C60 and C70 Fullerenes Containing a Uniform Distribution of Pyrenes and Adjacent Pentagons
Authors: Zettergren Henning , Alcamí Manuel , Martín Fernando 
Published: April 2008

AbstractThe most abundant fullerenes, C60 and C70, and all the pure carbon fullerenes larger than C70, follow the isolated‐pentagon rule (IPR). Non‐IPR fullerenes containing adjacent pentagons (APs) have been stabilized experimentally in cases where, according to Euler’s theorem, it is topologically impossible to isolate all the pentagons from each other. Surprisingly, recent experiments have shown that a few endohedral fullerenes, for which IPR structures are possible, are stabilized in non‐IPR cages. We show that, apart from strain, the physical property that governs the relative stabilities of fullerenes is the charge distribution in the cage. This charge distribution is controlled by the number and location of APs and pyrene motifs. We show that, when these motifs are uniformly distributed in the cage and well‐separated from one other, stabilization of non‐IPR endohedral and exohedral derivatives, as well as pure carbon fullerene anions and cations, is the rule, rather than the exception. This suggests that non‐IPR derivatives might be even more common than IPR ones.
Time‐mode circuits for analog computation
Authors: Ravinuthula Vishnu , Garg Vaibhav , Harris John G. , Fortes José A. B. 
Published: April 2008

AbstractWe introduce time‐mode circuits, a set of basic circuit building blocks for analog computation using a temporal step function representation for the inputs and outputs. These novel time‐mode circuits are low power, provide good noise performance and offer improved dynamic range. The design, IC implementation and detailed theoretical signal‐to‐noise ratio (SNR) analysis of a prototype time‐mode circuit—a weighted average computation circuit—are discussed. This new way of computation is studied with respect to existing conventional voltage‐mode and current‐mode circuits. Two possible applications of these time‐mode circuits are presented: an edge detection circuit for 16 pixels and a 3‐tap FIR filter that provides an SNR of 64 dB. Copyright © 2008 John Wiley & Sons, Ltd.