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Selected AbstractsNanoparticles for Drug Delivery Prepared from Amphiphilic PLGA Zwitterionic Block Copolymers with Sharp Contrast in Polarity between Two Blocks,ANGEWANDTE CHEMIE, Issue 22 2010Zhiqiang Cao Blockcopolymere aus Poly(carboxybetain) (PCB) und Poly(milchsäure-co-glycolsäure) (PLGA) mit tBu-Gruppen als Teil der PCB-Monomere bilden außergewöhnlich stabile PLGA-Kern/PCB-Schale-Nanopartikel, die aufgrund der COO, -Gruppen in der PCB-Schale ein hohes Funktionalisierungspotenzial aufweisen (siehe Bild; EDC=1-Ethyl-3-(3-dimethylaminopropyl)carbodiimid, NHS=N -Hydroxysuccinimid). [source] Labor productivity of small and large manufacturing firms: the case of TaiwanCONTEMPORARY ECONOMIC POLICY, Issue 3 2000M. Hsu This work studies the factors influencing the labor productivity of small and medium-sized enterprises (SMEs) and large firms using Taiwan as a case study. A special emphasis is placed on two possible international channels: exports and foreign direct investment (FDI). Different from conventional studies, we employ the two-stage switching regressions to correct the firm-size effect on labor productivity and estimate labor productivity for SMEs and large firms. The main findings are as follows. First, the estimates of the selectivity variable are statistically significant for both SMEs and large firms, supporting the hypothesis of correcting the effect of firm-size truncation. Second, while a larger trade intensity significantly increases the labor productivity of SMEs, it deteriorates significantly that of large firms. Third, FDI enhances the labor productivity of SMEs internally, whereas it has a negative spillover on that of other small and large firms in the industry. While the first outcome lends supports to the role of self-selection, the remaining stands in sharp contrast to conventional wisdom. [source] Kinesin-5 is not essential for mitotic spindle elongation in DictyosteliumCYTOSKELETON, Issue 11 2008Irina Tikhonenko Abstract The proper assembly and operation of the mitotic spindle is essential to ensure the accurate segregation of chromosomes and to position the cytokinetic furrow during cell division in eukaryotes. Not only are dynamic microtubules required but also the concerted actions of multiple motor proteins are necessary to effect spindle pole separation, chromosome alignment, chromatid segregation, and spindle elongation. Although a number of motor proteins are known to play a role in mitosis, there remains a limited understanding of their full range of functions and the details by which they interact with other spindle components. The kinesin-5 (BimC/Eg5) family of motors is largely considered essential to drive spindle pole separation during the initial and latter stages of mitosis. We have deleted the gene encoding the kinesin-5 member in Dictyostelium, (kif13), and find that, in sharp contrast with results found in vertebrate, fly, and yeast organisms, kif13, cells continue to grow at rates indistinguishable from wild type. Phenotype analysis reveals a slight increase in spindle elongation rates in the absence of Kif13. More importantly, there is a dramatic, premature separation of spindle halves in kif13, cells, suggesting a novel role of this motor in maintaining spindle integrity at the terminal stages of division. Cell Motil. Cytoskeleton 2008. © 2008 Wiley-Liss, Inc. [source] Tropomyosin expression and dynamics in developing avian embryonic musclesCYTOSKELETON, Issue 5 2008Jushuo Wang Abstract The expression of striated muscle proteins occurs early in the developing embryo in the somites and forming heart. A major component of the assembling myofibrils is the actin-binding protein tropomyosin. In vertebrates, there are four genes for tropomyosin (TM), each of which can be alternatively spliced. TPM1 can generate at least 10 different isoforms including the striated muscle-specific TPM1, and TPM1,. We have undertaken a detailed study of the expression of various TM isoforms in 2-day-old (stage HH 10,12; 33 h) heart and somites, the progenitor of future skeletal muscles. Both TPM1, and TPM1, are expressed transiently in embryonic heart while TPM1, is expressed in somites. Both RT-PCR and in situ hybridization data suggest that TPM1, is expressed in embryonic heart whereas TPM1, is expressed in embryonic heart, and also in the branchial arch region of somites, and in the somites. Photobleaching studies of Yellow Fluorescent Protein-TPM1, and -TPM1, expressed in cultured avian cardiomyocytes revealed that the dynamics of the two probes was the same in both premyofibrils and in mature myofibrils. This was in sharp contrast to skeletal muscle cells in which the fluorescent proteins were more dynamic in premyofibrils. We speculate that the differences in the two muscles is due to the appearance of nebulin in the skeletal myocytes premyofibrils transform into mature myofibrils. Cell Motil. Cytoskeleton 2008. © 2008 Wiley-Liss, Inc. [source] Hemidesmosome protein dynamics in live epithelial cellsCYTOSKELETON, Issue 2 2003Daisuke Tsuruta Abstract Hemidesmosomes mediate stable anchorage of epithelial cells to laminin-5 in the basement membrane zone and have been likened to spot-welds. Indeed, it has been assumed that hemidesmosomes are not dynamic, at least when compared to other matrix adhesion sites including focal contacts. We tested this notion by monitoring the fate of green fluorescent protein (GFP)-tagged human integrin ,4 subunit (GFP-h,4) and GFP-tagged 180-kD human bullous pemphigoid (BP) autoantigen (GFP-BP180) in live cultures of 804G cells that assemble numerous mature hemidesmosomes. In subconfluent 804G cells, both GFP-h,4 and GFP-BP180 protein clusters are not stable but assemble into and disassemble out of cat paw,like arrays at a relatively rapid rate. In confluent populations of 804G cells, although some cat paw,like clusters of both GFP-h,4 and GFP-BP180 are stable over periods of >60 min, other GFP-h,4 and GFP-BP180 protein arrays form and/or disappear during the same time period. Moreover, individual labeled particles show considerable motility in the plane of the membrane. Fluorescence recovery after photobleaching analyses provide a further indication of the dynamics of hemidesmosome proteins. In particular, bleached GFP-h,4 protein clusters in confluent cells recover signal within about 30 min, indicating that there is a relatively rapid turnover of hemidesmosome components in protein arrays clustered along the substratum attached surface of a cell. The rate of recovery is dependent on an intact microfilament system. In sharp contrast, bleached GFP-BP180 protein clusters in confluent cells fail to recover signal even when observed for longer than 60 min. To evaluate hemidesmosome protein dynamics in motile cells, we monitored GFP-h,4 and GFP-BP180 in 804G cells populating scrape wound sites in vitro. In these migratory cells, which lack mature hemidesmosomes, integrin ,4 subunit and BP180 protein clusters progressively assemble and disassemble into linear and cat-paw arrays. In summary, hemidesmosome protein clusters, like their counterparts in focal contacts, are dynamic. We discuss these results in relation to hemidesmosome functions. Cell Motil. Cytoskeleton 54:122,134, 2003. © 2003 Wiley-Liss, Inc. [source] Operational sex ratio, sexual conflict and the intensity of sexual selectionECOLOGY LETTERS, Issue 5 2008Patrick S. Fitze Abstract Modern sexual selection theory indicates that reproductive costs rather than the operational sex ratio predict the intensity of sexual selection. We investigated sexual selection in the polygynandrous common lizard Lacerta vivipara. This species shows male aggression, causing high mating costs for females when adult sex ratios (ASR) are male-biased. We manipulated ASR in 12 experimental populations and quantified the intensity of sexual selection based on the relationship between reproductive success and body size. In sharp contrast to classical sexual selection theory predictions, positive directional sexual selection on male size was stronger and positive directional selection on female size weaker in female-biased populations than in male-biased populations. Thus, consistent with modern theory, directional sexual selection on male size was weaker in populations with higher female mating costs. This suggests that the costs of breeding, but not the operational sex ratio, correctly predicted the strength of sexual selection. [source] Campaign Contributions and Agricultural SubsidiesECONOMICS & POLITICS, Issue 3 2001Rigoberto A. Lopez This article examines the influence of campaign contributions on agricultural subsidies. Empirical results revealed that rent-seeking works, i.e. contributions, influence agricultural subsidies in the manner they best serve contributors' economic interests. Eliminating campaign contributions would significantly decrease agricultural subsidies, hurt farm groups, benefit consumers and taxpayers, and increase social welfare by approximately $5.5 billion. Although contributions are not the only determinants of agricultural subsidies, investment returns to farm PAC contributors are quite high ($1 in contributions brings about $2,000 in policy transfers). In fact, the results are in sharp contrast to the "truthful contributions" assumption of the Grossman,Helpman model. [source] Frequencies of micronuclei in bank voles from zones of high radiation at Chornobyl, UkraineENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2000Brenda E. Rodgers Abstract A population of Clethrionomys glareolus (bank vole) from a highly radioactive area within the Chornobyl, Ukraine exclusion zone was sampled in June 1997 and in June and October 1998. Internal radiation doses from radiocesium were estimated to be as high as 8 rads/d. Total dose, which takes into account the internal dose from radiostrontium and the surrounding environment, was estimated to be 15 to 20 rads/d. In contrast, individuals from a reference population lying outside of the exclusion zone registered negligible levels of contamination. We used the micronucleus test in a double-blind study to analyze blood samples from 58 individuals. We scored more than 600,000 polychromatic erythrocytes (PCEs) but could not reject the null hypothesis that the frequency of micronucleated PCEs in voles exposed to radiation was equal to the frequency in unexposed voles. Results of our study stand in sharp contrast to earlier reports of increased frequencies of micronuclei in rodents exposed to fallout of the Chornobyl accident, but with radiation doses that were orders of magnitude lower than those reported here. Radioresistance and experimental methods are possible explanations for these differences in the results. [source] Paucity of enkephalin production in neostriatal striosomal neurons: analysis with preproenkephalin,green fluorescent protein transgenic miceEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 10 2008Yoshinori Koshimizu Abstract Whether or not the striosome compartment of the neostriatum contained preproenkephalin (PPE)-expressing neurons remained unresolved. To address this question by developing a sensitive detection method, we generated transgenic mice expressing enhanced green fluorescent protein (GFP) under the specific transcriptional control of the PPE gene. Eight transgenic lines were established, and three of them showed GFP expression which was distributed in agreement with the reported localization of PPE mRNA in the central nervous system. Furthermore, in the matrix compartment of the neostriatum of the three lines, intense GFP immunoreactivity was densely distributed in the neuronal cell bodies and neuropil, and matrix neurons displayed > 94% co-localization for GFP and PPE immunoreactivities. In sharp contrast, GFP immunoreactivity was very weak in the striosome compartment, which was characterized by intense immunoreactivity for mu-opioid receptors (MOR). Although neostriatal neurons were divided into GFP-immunopositive and -negative groups in both the striosome and matrix compartments, GFP immunoreactivity of cell bodies was much weaker (,1/5) in GFP-positive striosomal neurons than in GFP-positive matrix neurons. A similar reciprocal organization of PPE and MOR expression was also suggested in the ventral striatum, because GFP immunoreactivity was weaker in intensely MOR-immunopositive regions than in the surrounding MOR-negative regions. As PPE-derived peptides are endogenous ligands for MOR in the neostriatum and few axon collaterals of matrix neurons enter the striosome compartment, the present results raised the question of the target of those peptides produced abundantly by matrix neurons. [source] Emotional reactions to harmful intergroup behaviorEUROPEAN JOURNAL OF SOCIAL PSYCHOLOGY, Issue 1 2006Ernestine H. Gordijn In this paper, we examined reactions to situations in which, although one is not personally involved, one could see oneself connected to either the perpetrators or the victims of unfair behavior. We manipulated participants' similarity and measured their identification to either one of two groups which participants later learned was the victim or the perpetrator of harmful behavior. As predicted, making salient similarities to the victims lead participants to: 1) appraise the perpetrator's behavior as more unfair; 2) experience more anger; and 3) be more likely to take action against it and less prone to show support for it as a function of their level of identification with their salient ingroup. In sharp contrast, focusing participants' attention on their similarities to the perpetrators reversed this pattern of findings: Compared to high identifiers, low identifiers appraised the behavior as more unfair than high identifiers, which made them feel angry (and guilty) and less likely to show support for the perpetrator's behavior. The data also provide strong support for a mediational model in which appraisal of the situation colors the emotional reaction which in turn orients action tendencies. We discuss the implications of our findings for the issue of group-based emotions. Copyright © 2006 John Wiley & Sons, Ltd. [source] DRIFT PROMOTES SPECIATION BY SEXUAL SELECTIONEVOLUTION, Issue 3 2009Josef C. Uyeda Quantitative genetic models of sexual selection have generally failed to provide a direct connection to speciation and to explore the consequences of finite population size. The connection to speciation has been indirect because the models have treated only the evolution of male and female traits and have stopped short of modeling the evolution of sexual isolation. In this article we extend Lande's (1981) model of sexual selection to quantify predictions about the evolution of sexual isolation and speciation. Our results, based on computer simulations, support and extend Lande's claim that drift along a line of equilibria can rapidly lead to sexual isolation and speciation. Furthermore, we show that rapid speciation can occur by drift in populations of appreciable size (Ne, 1000). These results are in sharp contrast to the opinion of many researchers and textbook writers who have argued that drift does not play an important role in speciation. We argue that drift may be a powerful amplifier of speciation under a wide variety of modeling assumptions, even when selection acts directly on female mating preferences. [source] An evolutionary view on tooth development and replacement in wild Atlantic salmon (Salmo salar L.)EVOLUTION AND DEVELOPMENT, Issue 1 2008A. Huysseune SUMMARY To gain an insight into the evolution of tooth replacement mechanisms, we studied the development of first-generation and replacement teeth on the dentary of wild Atlantic salmon (Salmo salar L.), a protacanthopterygian teleost, using serially sectioned heads of early posthatching stages as well as adults. First-generation teeth develop within the oral epithelium. The anlage of the replacement tooth is first seen as a placode-like thickening of the outer dental epithelium of the predecessor, at its lingual and caudal side. Ongoing development of the replacement tooth germ is characterized by the elaboration of a population of epithelial cells, termed here the middle dental epithelium, apposed to the inner dental epithelium on the lingual side of the tooth germ. Before the formation of the new successor, a single-layered outer dental epithelium segregates from the middle dental epithelium. The dental organs of the predecessor and the successor remain broadly interconnected. The absence of a discrete successional dental lamina in salmon stands in sharp contrast to what is observed in other teleosts, even those that share with salmon the extraosseous formation of replacement teeth. The mode of tooth replacement in Atlantic salmon displays several characters similar to those observed in the shark Squalus acanthias. To interpret similarities in tooth replacement between Atlantic salmon and chondrichthyans as a case of convergence, or to see them as a result of a heterochronic shift, requires knowledge on the replacement process in more basal actinopterygian lineages. The possibility that the middle dental epithelium functionally substitutes for a successional lamina, and could be a source of stem cells, whose descendants subsequently contribute to the placode of the new replacement tooth, needs to be explored. [source] Potency and selectivity of inhibition of cathepsin K, L and S by their respective propeptidesFEBS JOURNAL, Issue 20 2000Jocelyne Guay The prodomains of several cysteine proteases of the papain family have been shown to be potent inhibitors of their parent enzymes. An increased interest in cysteine proteases inhibitors has been generated with potential therapeutic targets such as cathepsin K for osteoporosis and cathepsin S for immune modulation. The propeptides of cathepsin S, L and K were expressed as glutathione S -transferase-fusion proteins in Escherichia coli. The proteins were purified on glutathione affinity columns and the glutathione S -transferase was removed by thrombin cleavage. All three propeptides were tested for inhibitor potency and found to be selective within the cathepsin L subfamily (cathepsins K, L and S) compared with cathepsin B or papain. Inhibition of cathepsin K by either procathepsin K, L or S was time-dependent and occurred by an apparent one-step mechanism. The cathepsin K propeptide had a Ki of 3.6,6.3 nm for each of the three cathepsins K, L and S. The cathepsin L propeptide was at least a 240-fold selective inhibitor of cathepsin K (Ki = 0.27 nm) and cathepsin L (Ki = 0.12 nm) compared with cathepsin S (Ki = 65 nm). Interestingly, the cathepsin S propeptide was more selective for inhibition of cathepsin L (Ki = 0.46 nm) than cathepsin S (Ki = 7.6 nm) itself or cathepsin K (Ki = 7.0 nm). This is in sharp contrast to previously published data demonstrating that the cathepsin S propeptide is equipotent for inhibition of human cathepsin S and rat and paramecium cathepsin L [Maubach, G., Schilling, K., Rommerskirch, W., Wenz, I., Schultz, J.E., Weber, E. & Wiederanders, B. (1997), Eur J. Biochem. 250, 745,750]. These results demonstrate that limited selectivity of inhibition can be measured for the procathepsins K, L and S vs. the parent enzymes, but selective inhibition vs. cathepsin B and papain was obtained. [source] Long-range foraging by the honey-bee, Apis mellifera L.FUNCTIONAL ECOLOGY, Issue 4 2000M. Beekman Abstract 1.,Waggle dances of honey-bees (Apis mellifera L.) were decoded to determine where and how far the bees foraged during the blooming of heather (Calluna vulgaris L.) in August 1996 using a hive located in Sheffield, UK, east of the heather moors. The median distance foraged was 6·1 km, and the mean 5·5 km. Only 10% of the bees foraged within 0·5 km of the hive whereas 50% went more than 6 km, 25% more than 7·5 km and 10% more than 9·5 km from the hive. 2.,These results are in sharp contrast with previous studies in which foraging distances were much closer to the hive. In May 1997 the mean foraging distance was 1 km, showing that long-range dancing is not the rule in Sheffield. 3.,The observed foraging distances described in this study may not be exceptional in a patchy environment where differences in patch size and patch quality are large. When travel distances to patches are large, distant patches can probably be utilized only by individuals that live in groups and recruit foragers to the patches found. Only then are the benefits of scouting for distant patches high enough to enable the exploitation of these patches. [source] Rational Design of Charge-Neutral, Near-Infrared-Emitting Osmium(II) Complexes and OLED FabricationADVANCED FUNCTIONAL MATERIALS, Issue 16 2009Tsang-Chi Lee Abstract A new series of charge neutral Os(II) isoquinolyl triazolate complexes (1,4) with both trans and cis arrangement of phosphine donors are synthesized, and their structural, electrochemical and photophysical properties are established. In sharp contrast to the cis -arranged complexes 2,4, the trans derivative 1, which shows a planar arrangement of chromophoric N -substituted chelates, offers the most effective extended , -delocalization and hence the lowest excited state energy gap. These complexes exhibit phosphorescence with peak wavelengths ranging from 692,805,nm in degassed CH2Cl2 at room temperature. Near-infrared (NIR)-emitting electroluminescent devices employing 6,wt % of 1 (or 4) doped in Alq3 host material are successfully fabricated. The devices incorporating 1 as NIR phosphor exhibit fairly intense emission with a peak wavelength at 814,nm. Forward radiant emittance reaches as high as 65.02,µW,cm,2, and a peak EQE of ,1.5% with devices employing Alq3, TPBi and/or TAZ as electron-transporting/exciton-blocking layers. Upon switching to phosphor 4, the electroluminescence blue shifts to 718,nm, while the maximum EQE and radiance increase to 2.7% and 93.26 (,W,cm,2) respectively. Their performances are optimized upon using TAZ as the electron transporting and exciton-blocking material. The OLEDs characterized represent the only NIR-emitting devices fabricated using charge-neutral and volatile Os(II) phosphors via thermal vacuum deposition. [source] Rational Design of Chelating Phosphine Functionalized Os(II) Emitters and Fabrication of Orange Polymer Light-Emitting Diodes Using Solution Process,ADVANCED FUNCTIONAL MATERIALS, Issue 2 2008M. Cheng Abstract A new series of charge neutral Os(II) pyridyl azolate complexes with either bis(diphenylphosphino)methane (dppm) or cis -1,2-bis(diphenylphosphino)ethene (dppee) chelates were synthesized, and their structural, electrochemical, photophysical properties and thermodynamic relationship were established. For the dppm derivatives 3a and 4a, the pyridyl azolate chromophores adopt an eclipse orientation with both azolate segments aligned trans to each other, and with the pyridyl groups resided the sites that are opposite to the phosphorus atoms. In sharp contrast, the reactions with dppee ligand gave rise to the formation of two structural isomers for all three kind of azole chromophores, with both azolate or neutral heterocycles (i.e., pyridyl or isoquinolinyl fragments) located at the mutual trans -disposition around the Os metal (denoted as series of a and b complexes). These chelating phosphines Os(II) complexes show remarkably high thermal stability, among which and several exhibit nearly unitary phosphorescence yield in deaerated solution at RT. A polymer light-emitting device (PLED) prepared using 0.4 mol % of 5a as dopant in a blend of poly(vinylcarbazole) (PVK) and 30 wt % of 2- tert -butylphenyl-5-biphenyl-1,3,4-oxadiazole (PBD) exhibits yellow emission with brightness of 7208 cd m,2, an external quantum efficiency of 10.4 % and luminous efficiency of 36.1 cd A,1 at current density of 20 mA cm,2. Upon changing to 1.6 mol % of 6a, the result showed even better brightness of 9212 cd m,2, external quantum efficiency of 12.5 % and luminous efficiency of 46.1 cd A,1 at 20 mA cm,2, while the max. external quantum efficiency of both devices reaches as high as 11.7 % and 13.3 %, respectively. The high PL quantum efficiency, non-ionic nature, and short radiative lifetime are believed to be the determining factors for this unprecedented achievement. [source] Leptin-mediated neovascularization is a prerequisite for progression of nonalcoholic steatohepatitis in rats,HEPATOLOGY, Issue 4 2006Mitsuteru Kitade Nonalcoholic steatohepatitis (NASH) may cause fibrosis, cirrhosis, and hepatocellular carcinoma (HCC); however, the exact mechanism of disease progression is not fully understood. Angiogenesis has been shown to play an important role in the progression of chronic liver disease. The aim of this study was to elucidate the role of angiogenesis in the development of liver fibrosis and hepatocarcinogenesis in NASH. Zucker rats, which naturally develop leptin receptor mutations, and their lean littermate rats were fed a choline-deficient, amino acid,defined diet. Both Zucker and littermate rats showed marked steatohepatitis and elevation of oxidative stress markers (e.g., thiobarbital acid reactive substances and 8-hydroxydeoxyguanosine). In sharp contrast, liver fibrosis, glutathione- S -transferase placental form (GST-P)-positive preneoplastic lesions, and HCC developed in littermate rats but not in Zucker rats. Hepatic neovascularization and the expression of vascular endothelial growth factor (VEGF), a potent angiogenic factor, only increased in littermate rats, almost in parallel with fibrogenesis and carcinogenesis. The CD31-immunopositive neovessels were mainly localized either along the fibrotic septa or in the GST-P,positive lesions. Our in vitro study revealed that leptin exerted a proangiogenic activity in the presence of VEGF. In conclusion, these results suggest that leptin-mediated neovascularization coordinated with VEGF plays an important role in the development of liver fibrosis and hepatocarcinogenesis in NASH. (HEPATOLOGY 2006;44:983,991.) [source] Ultrathin Direct Atomic Layer Deposition on Composite Electrodes for Highly Durable and Safe Li-Ion BatteriesADVANCED MATERIALS, Issue 19 2010Yoon Seok Jung Direct atomic layer deposition (ALD) on composite electrodes leads to ultrathin conformal protective coatings without disrupting inter-particle electronic pathways. Al2O3 -coated natural graphite (NG) electrodes obtained by direct ALD on the as-formed electrode show exceptionally durable capacity retention even at an elevated temperature of 50,°C. In sharp contrast, ALD on powder results in poorer cycle retention than bare NG. [source] A fast, one-equation integration algorithm for the Lemaitre ductile damage modelINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 8 2002E. A. de Souza NetoArticle first published online: 3 MAY 200 Abstract This paper introduces an elastic predictor/return mapping integration algorithm for a simplified version of the Lemaitre ductile damage model, whose return mapping stage requires the solution of only one scalar non-linear equation. The simplified damage model differs from its original counterpart only in that it excludes kinematic hardening. It can be used to predict ductile damage growth whenever load reversal is absent or negligible,a condition met in a vast number of practical engineering applications. The one-equation integration scheme proves highly efficient in the finite element solution of typical boundary value problems, requiring computation times comparable to those observed in classical von Mises implementations. This is in sharp contrast to the previously proposed implementations of the original model whose return mapping may require, in the most general case, the solution of a system of 14 coupled algebraic equations. For completeness, a closed formula for the corresponding consistent tangent operator is presented. The performance of the algorithm is illustrated by means of a numerical example. Copyright © 2002 John Wiley & Sons, Ltd. [source] Highly Regioselective and Rapid Hydroformylation of Alkyl Acrylates Catalyzed by a Rhodium Complex with a Tetraphosphorus LigandADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 4 2009Shichao Yu Abstract Alkyl acrylates have been hydroformylated to the linear aldehydes with high regioselectivity (linear/branch>99/1) and extraordinarily high average turnover frequencies (up to 5400,h,1) by using a rhodium complex with a tetraphosphorus ligand. This protocol is in sharp contrast to the most of other processes that favor production of the branched aldehyde (typically>95% branched for most Rh-catalyzed reaction systems). The high turnover number achieved by this new catalytic system is also remarkable considering the less reactive character of alkyl acrylates to the hydroformylation reaction conditions. [source] Predicting Stock Market Returns with Aggregate Discretionary AccrualsJOURNAL OF ACCOUNTING RESEARCH, Issue 4 2010QIANG KANG ABSTRACT We find that the positive relation between aggregate accruals and one-year-ahead market returns documented in Hirshleifer, Hou, and Teoh [2009] is driven by discretionary accruals but not normal accruals. The return forecasting power of aggregate discretionary accruals is robust to choices of sample periods, return measurements, estimation methods, business condition and risk premium proxies, and accrual models used to isolate discretionary accruals. Our extensive analysis shows that aggregate discretionary accruals, in sharp contrast to aggregate normal accruals, contain little information about overall business conditions or aggregate cash flows and display little co-movement with ICAPM-motivated risk premium proxies. Our findings imply that aggregate discretionary accruals likely reflect aggregate fluctuations in earnings management, thereby favoring the behavioral explanation that managers time aggregate equity markets to report earnings. [source] p53/CEP-1 increases or decreases lifespan, depending on level of mitochondrial bioenergetic stressAGING CELL, Issue 4 2009Natascia Ventura Summary Mitochondrial pathologies underlie a number of life-shortening diseases in humans. In the nematode Caenorhabditis elegans, severely reduced expression of mitochondrial proteins involved in electron transport chain-mediated energy production also leads to pathological phenotypes, including arrested development and/or shorter life; in sharp contrast, mild suppression of these same proteins extends lifespan. In this study, we show that the C. elegans p53 ortholog cep-1 mediates these opposite effects. We found that cep-1 is required to extend longevity in response to mild suppression of several bioenergetically relevant mitochondrial proteins, including frataxin , the protein defective in patients with Friedreich's Ataxia. Importantly, we show that cep-1 also mediates both the developmental arrest and life shortening induced by severe mitochondrial stress. These findings support an evolutionarily conserved function for p53 in modulating organismal responses to mitochondrial dysfunction and suggest that metabolic checkpoint responses may play a role in longevity control and in human mitochondrial-associated diseases. [source] Structure determination of N -methyl-tetrahydro-5H -indazol-5-onesJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 3 2006Kurt A. Josef This paper communicates the (regio) synthesis and a convenient NMR structural assignment method for N -methyl-tetrahydro-5H -indazol-5-one isomers. The cyclization reaction of 7-(hydroxymethylene)-1,4-dioxaspiro[4,5]decan-8-one (3) with methylhydrazine yields, after de-protection predominately the N-2 methyl isomer 2. Analysis of the product ratio and structural assignments are based on NMR data including NOE difference experiments and subsequently confirmed with X-ray crystallography. These findings are in sharp contrast with the literature. The experimental conditions used to optimize the synthesis of the individual isomers are discussed. [source] Differentiating emotional intelligence in leadershipJOURNAL OF LEADERSHIP STUDIES, Issue 2 2007Carina Fiedeldey-Van Dijk Leadership has received considerable attention since the 1990s. We claim that leaders can be found at all levels of employment, and at the very least, all managers are expected to be leaders. Yet managerial status does not guarantee leadership. Leadership is a necessary component of and a filter for successful management. Effective managers demonstrate leadership capabilities. Leadership attributes are well captured in measures of emotional intelligence (EQ). Hence, leadership can improve if managers work to develop their EQ. We show how EQ, and hence leadership, can vary by level of employment among a composite international group of 3,305 employees with the Six Seconds Emotional Intelligence Assessment. The relationship between six leadership groups, as based on their EQ performance, across different employment levels was statistically examined, suggesting that leadership is realized in different ways depending on level of employment. It appears that employees become more skillful in emotional literacy and consequential thinking as they progress up the employment ladder. Intrinsic motivation and optimism are best leveraged by nonmanagerial rather than senior employees. The diminishing incorporation of empathy with an increase in employment level seems to stand in sharp contrast. Nonmanagerial employees, specialists, and entrepreneurs will benefit from developing their competence in pursuing their objectives with an overarching sense of purpose. The finding that high-EQ leaders seem to dominate in the managerial levels may be viewed as encouraging. [source] A method for the direct electrical stimulation of the auditory system in deaf subjects: A functional magnetic resonance imaging studyJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 1 2002Adnan Z. Alwatban BSc Abstract Purpose To develop a safe functional magnetic resonance imaging (fMRI) procedure for auditory assessment of deaf subjects. Materials and Methods A gold-plated tungsten electrode has been developed which has zero magnetic susceptibility. Used with carbon leads and a carbon reference pad, it enables safe, distortion-free fMRI studies of deaf subjects following direct electrical stimulation of the acoustic nerve. Minor pickup of the radio frequency (RF) pulses by the electrode assembly is difficult to eliminate, and a SPARSE acquisition sequence is used to avoid any effects of unintentional auditory nerve stimulation. Results The procedure is demonstrated in a deaf volunteer. Activation is observed in the contralateral but not the ipsilateral primary auditory cortex. This is in sharp contrast to studies of auditory processing in hearing subjects, but consistent with the small number of previous positron emission tomography (PET) and MR studies on adult deaf subjects. Conclusion The fMRI procedure is able to demonstrate whether the auditory pathway is fully intact, and may provide a useful method for preoperative assessment of candidates for cochlear implantation. J. Magn. Reson. Imaging 2002;16:6,12. © 2002 Wiley-Liss, Inc. [source] Transforming powder mechanical properties by core/shell structure: Compressible sandJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 11 2010Limin Shi Abstract Some active pharmaceutical ingredients possess poor mechanical properties and are not suitable for tableting. Using fine sand (silicon dioxide), we show that a core/shell structure, where a core particle (sand) is coated with a thin layer of polyvinylpyrrolidone (PVP), can profoundly improve powder compaction properties. Sand coated with 5% PVP could be compressed into intact tablets. Under a given compaction pressure, tablet tensile strength increases dramatically with the amount of coating. This is in sharp contrast to poor compaction properties of physical mixtures, where intact tablets cannot be made when PVP content is 20% or less. The profoundly improved tabletability of core/shell particles is attributed to the formation of a continuous three-dimensional bonding network in the tablet. © 2010 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:4458,4462, 2010 [source] GLOBAL SYSTEMATIC AND PHYLOGENETIC ANALYSIS OF SARGASSUM IN THE GULF OF MEXICO, CARIBBEAN AND PACIFIC BASINJOURNAL OF PHYCOLOGY, Issue 2000N. Phillips Sargassum is one of the most species-rich genera in the brown algae with over 400 described species worldwide. The bulk of these species occurs in Pacific-Indian ocean waters with only a small portion found on the Atlantic side of the Isthmus of Panama. Sargassum also has one of the most subdivided and complex taxonomic systems used within the algae. Systematic distinctions within the genus are further complicated by high rates of phenotypic variability in several key morphological characters. Molecular analyses in such systems should allow testing of systematic concepts while providing insights into speciation and evolutionary patterns. Global molecular phylogenetic analyses using both conserved and variable regions of the Rubisco operon (rbcL and rbcL-IGS-rbcS) were performed with species from the Gulf of Mexico, Caribbean, and Pacific basin. Results confirm earlier analyses based on rbcL-IGS- rbcS from Pacific species at the subgeneric and sectional level while providing additional insights into the systematics and phylogenetics on a global scale. For example, species east of the Isthmus of Panama form a distinct well-resolved clade within the tropical subgenus. This result in sharp contrast to traditional systematic treatments but provides a window into the evolutionary history of this genus in the Pacific and Atlantic Ocean basins and a possible means to time speciation events. [source] Organic biradical compounds with a mesogenic core and long alkoxy groups: preparation, structures and magnetic propertiesJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 5 2006Shin'ichi Nakatsuji Abstract Series of organic biradical compounds 3a,3h consisting of a mesogenic core (biphenyl, naphthalene, azobenzene and azoxybenzene) and long alkoxy groups with PROXYL or TEMPO radicals were prepared. The TEMPO derivatives (3b, 3d, 3f, and 3h) were found to show fairly large antiferromagnetic interactions (J,=,,34,,,,45,K) being well expressed by singlet-triplet model irrespective of the mesogenic cores and the behavior is understandable by taking a hand-in-hand like assembled structure into consideration. On the other hand, only weak antiferromagnetic interactions with Curie,Weiss behavior were observed in all of the PROXYL derivatives (3a, 3c, 3e, and 3d) affording a sharp contrast with the TEMPO-based biradicals. Copyright © 2006 John Wiley & Sons, Ltd. [source] The neuroprotective activities of melatonin against the Alzheimer ,-protein are not mediated by melatonin membrane receptorsJOURNAL OF PINEAL RESEARCH, Issue 3 2002Miguel A. Pappolla Exposure of neuronal cells to the Alzheimer's amyloid , protein (A,) results in extensive oxidative damage of bio-molecules that are profoundly harmful to neuronal homeostasis. It has been demonstrated that melatonin protects neurons against A, -mediated neurotoxicity, including cell death and a spectrum of oxidative lesions. We undertook the current study to determine whether melatonin membrane receptors are involved in the mechanism of neuroprotection against A, neurotoxicity. For this purpose, we characterized the free-radical scavenging potency of several compounds exhibiting various affinities for melatonin membrane receptors (MLT 1a and 1b). A, -mediated neurotoxicity was assessed in human neuroblastoma cells and in primary hippocampal neurons. In sharp contrast with melatonin, no neuroprotection against A, toxicity was observed when we used melatonin membrane receptor agonists that were devoid of antioxidant activity. In contrast, the cells were fully protected in parallel control experiments when either melatonin, or the structurally unrelated free-radical scavenger phenyl- N - t -butyl nitrone (PBN), were added to A, -containing culture media. This study demonstrates that the neuroprotective properties of melatonin against A, -mediated toxicity does not require binding of melatonin to a membrane receptor and is likely the result of the antioxidant and antiamyloidogenic features of the agent. [source] Chromatographic classification and comparison of commercially available perfluorinated stationary phases for reversed-phase liquid chromatography using Principal Component AnalysisJOURNAL OF SEPARATION SCIENCE, JSS, Issue 3-4 2003Melvin R. Euerby Abstract A range of ten perfluorophenyl and perfluoroalkyl stationary phases has been evaluated using standard chromatographic tests and probes. Principal Component Analysis of the data has indicated that the phases can be divided into distinct groupings. Extending the dataset to include standard alkyl and phenyl phases provided further data interpretation to support the orthogonal selectivity claims made for perfluorinated phases. The analysis of a range of basic analytes showed an unusual extended retention of hydrophilic basic analytes with perfluorophases. Furthermore, a non-linear relationship between the amount of organic modifier and the logarithm of the retention factor was observed, for the hydrophilic bases, which could not be modelled with LC prediction softwares. This was in sharp contrast to the alkyl and phenyl phases examined. Basic analyte retention on perfluoroalkyl phases could be modelled adequately for the lipophilic bases. Exploration of the retention mechanism of these perfluoro phases indicated that silanol interactions were important in retention and selectivity. Using a rapid, isocratic, high organic modifier methodology, it was possible to analyse a mixture containing a lipophilic steroid, hydrophilic base and an internal standard in < 4 minutes with a perfluorophenyl phase. This had previously only been achievable with an alkyl phase under gradient elution conditions. [source] | ||||||||||||||||||||||||||||||||||||||||||||||