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Direct Coupling (direct + coupling)
Selected AbstractsChemInform Abstract: Direct Coupling of Alcohols with Alkenylsilanes Catalyzed by Indium Trichloride or Bismuth Tribromide.CHEMINFORM, Issue 17 2009Yoshihiro Nishimoto Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Direct Coupling of Pyrroles with Carbonyl Compounds: Short Enantioselective Synthesis of (S)-Ketorolac (XII).CHEMINFORM, Issue 23 2005Phil S. Baran No abstract is available for this article. [source] ChemInform Abstract: Direct Coupling of Nucleophiles with Nitroaromatic Compounds via Fluoride-Promoted Oxidative Nucleophilic Aromatic Substitution for Hydrogen.CHEMINFORM, Issue 32 2001Inma Huertas Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] On-chip tryptic digest with direct coupling to ESI-MS using magnetic particlesELECTROPHORESIS, Issue 24 2008Anne Le Nel Abstract As a step toward a fully automated front-end microfluidic chip for MS proteomics, we propose a system capable of performing online tryptic digest and ESI-MS, using a replaceable on-chip digestion microcolumn based on self-assembled magnetic particles. [source] Separation of multiphosphorylated peptide isomers by CZEELECTROPHORESIS, Issue 21 2008Marika V. Muetzelburg Abstract A separation of mono, doubly and triply phosphorylated isomers was developed with CZE with an aqueous electrolyte containing 3.9,mol/L formic acid and 30%,v/v trifluoroethanol. Thus a mixture of ten phosphopeptides corresponding to the human tau sequence 226,240 was separated within 70,min. Although peptides with different phosphorylation degrees, i.e. 0,3 phosphate groups, were well separated, some of the phosphopeptide isomers containing one or two phosphate groups were only partially separated. The electrolyte system is compatible with both MALDI- and ESI-MS, allowing a direct coupling, and thus could have some interesting applications in proteomics. [source] Characterization of glyco isoforms in plasmaderived human antithrombin by on-line capillary zone electrophoresis-electrospray ionization-quadrupole ion trap-mass spectrometry of the intact glycoproteinsELECTROPHORESIS, Issue 13 2004Uwe M. Demelbauer Abstract The carbohydrate structures of five isoforms of ,-AT and two isoforms of ,-AT were determined by applying capillary zone electrophoresis (CZE) on-line coupled to electrospray ionization-mass spectrometry (ESI-MS) using an ion-trap analyzer. For the AT preparations gained from a plasma pool at least semiquantitative information on the isoform-distributions could be gained. Unlike to the commonly used approaches starting from enzymatically treated glycoproteins, this approach deals with intact proteins. The high accuracy of the molecular mass determination obtained by the ion-trap analyzer allows one to calculate and ascertain the carbohydrate composition assuming no variations in the protein moiety of AT and to exclude or confirm the presence of the potential post-translational or other modifications. Therefore, the direct coupling of CZE with ESI-MS does not only represent a fast alternative technique to two-dimensional electrophoresis (2-DE) but serves as a method which provides structural information complementary to that gained from peptide mapping methods. [source] Hydrogenase- and outer membrane c -type cytochrome-facilitated reduction of technetium(VII) by Shewanella oneidensis MR-1ENVIRONMENTAL MICROBIOLOGY, Issue 1 2008Matthew J. Marshall Summary Pertechnetate, 99Tc(VII)O4,, is a highly mobile radionuclide contaminant at US Department of Energy sites that can be enzymatically reduced by a range of anaerobic and facultatively anaerobic microorganisms, including Shewanella oneidensis MR-1, to poorly soluble Tc(IV)O2(s). In other microorganisms, Tc(VII)O4, reduction is generally considered to be catalysed by hydrogenase. Here, we provide evidence that although the NiFe hydrogenase of MR-1 was involved in the H2 -driven reduction of Tc(VII)O4,[presumably through a direct coupling of H2 oxidation and Tc(VII) reduction], the deletion of both hydrogenase genes did not completely eliminate the ability of MR-1 to reduce Tc(VII). With lactate as the electron donor, mutants lacking the outer membrane c -type cytochromes MtrC and OmcA or the proteins required for the maturation of c -type cytochromes were defective in reducing Tc(VII) to nanoparticulate TcO2·nH2O(s) relative to MR-1 or a NiFe hydrogenase mutant. In addition, reduced MtrC and OmcA were oxidized by Tc(VII)O4,, confirming the capacity for direct electron transfer from these OMCs to TcO4,. c -Type cytochrome-catalysed Tc(VII) reduction could be a potentially important mechanism in environments where organic electron donor concentrations are sufficient to allow this reaction to dominate. [source] Coherent corticomuscular oscillations originate from primary motor cortex: Evidence from patients with early brain lesionsHUMAN BRAIN MAPPING, Issue 10 2006Christian Gerloff Abstract Coherent oscillations of neurons in the primary motor cortex (M1) have been shown to be involved in the corticospinal control of muscle activity. This interaction between M1 and muscle can be measured by the analysis of corticomuscular coherence in the ,-frequency range (,-CMCoh; 14,30 Hz). Largely based on magnetoencephalographic (MEG) source-modeling data, it is widely assumed that ,-CMCoh reflects direct coupling between M1 and muscle. Deafferentation is capable of modulating ,-CMCoh, however, and therefore the influence of reafferent somatosensory signaling and corresponding neuronal activity in the somatosensory cortex (S1) has been unclear. We present transcranial magnetic stimulation (TMS) and MEG data from three adult patients suffering from congenital hemiparesis due to pre- and perinatally acquired lesions of the pyramidal tract. In these patients, interhemispheric reorganization had resulted in relocation of M1 to the contralesional hemisphere, ipsilateral to the paretic hand, whereas S1 had remained in the lesioned hemisphere. This topographic dichotomy allowed for an unequivocal topographic differentiation of M1 and S1 with MEG (which is not possible if M1 and S1 are directly adjacent within one hemisphere). In all patients, ,-CMCoh originated from the contralesional M1, in accordance with the TMS-evoked motor responses, and in contrast to the somatosensory evoked fields (SEFs) for which the sources (N20m) were localized in S1 of the lesioned hemisphere. These data provide direct evidence for the concept that ,-CMCoh reflects the motorcortical efferent drive from M1 to the spinal motoneuron pool and muscle. No evidence was found for a relevant contribution of neuronal activity in S1 to ,-CMCoh. Hum Brain Mapp, 2006. © 2006 Wiley-Liss, Inc. [source] Coupling of thermoelectric modules with a photovoltaic panel for air pre-heating and pre-cooling application; an annual simulationINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 14 2008Nolwenn Le Pierrès Abstract Thermoelectric (TE) modules are possible reversible pre-cooling and pre-heating devices for ventilation air in buildings. In this study, the opportunity of direct coupling of TE modules with photovoltaic (PV) cells is considered. This coupling is evaluated through a numerical simulation depending on the meteorological conditions of Chambéry, Alpine region in France, and on the cooling or heating use of the TE modules, through annual energy and exergy efficiencies. For the considered conditions, TE module performances are of the same order as the ones of the vapour compression heat pumps, with a TE coefficient of performance higher than 2 for low values of input DC current. The PV,TE coupling efficiency varies between 0.096 and 0.23 over the year, with an average value of 0.157. Evolutions of the exergy effectiveness of PV and TE elements follow the same trends as the corresponding energy efficiencies but with steeper variations for the coupling exergy yield that varies between 0.004 and 0.014, with an annual average value of 0.010. The direct PV,TE coupling does not seem to be a sustainable option for the summer cooling purpose particularly. A case study with indirect coupling under a warm climate is considered and shows that the use of TE devices could be efficient in housing to ensure summer thermal comfort, but the corresponding necessary PV area would induce a high investment. Copyright © 2008 John Wiley & Sons, Ltd. [source] DETECTION OF OLIVE OIL ADULTERATION WITH RAPESEED AND SUNFLOWER OILS USING MOS ELECTRONIC NOSE AND SMPE-MSJOURNAL OF FOOD QUALITY, Issue 1 2010SYLWIA MILDNER-SZKUDLARZ ABSTRACT The study analyzed the effectiveness of two types of electronic nose systems to detect adulteration of extra virgin olive oil (EVOO) with rapeseed and sunflower oils. Tested methods included volatile analysis with the electronic nose based on MOS sensors (HS-E nose) and by direct coupling of SPME to MS (SPME-MS). Volatile compounds were analyzed also by SPME-GC/MS. Samples of EVOO were mixed with different proportions, ranging from 5 to 50% (v/v), of seed oils and fingerprints of volatile profiles of all samples were generated. In order to obtain as much chemical information as possible and to find a volatile marker to detect adulterations of EVOO with seed oils, principal component analysis (PCA) and partial least squares (PLS) analyses were applied to the data. The application of PCA and PLS analyses to the data from two electronic noses and SMPE-GC/MS were sufficient to differentiate the adulterated samples from pure EVOO. Excellent results were obtained in the prediction of the percentage of adulteration by PLS analysis. SPME-GC-MS analysis with subsequent PCA yielded good results; however, it was time-consuming. The two electronic noses, with subsequent PCA treatment of data, offering the advantages of rapidity and reliability, enabled detection of olive oil adulteration with different contents of seed oils. PRACTICAL APPLICATIONS Virgin olive oil is highly appreciated by consumers due to its nutritional benefits. Thus, its adulteration with low-grade olive oils or cheaper vegetable oils could potentially be very profitable for sellers or raw material suppliers and may yield large economic profits. In this way, authentication of virgin olive oils has become an interesting subject from both commercial and health perspectives. It has been proved that the two proposed types of electronic nose systems facilitate reliable detection of rapeseed and sunflower oils in extra virgin olive oil. Both MOS and MS electronic noses are faster than the conventional SMPE-GC/MS analysis. These well-correlated methodologies, offering the advantages of rapidity and reliability, opened up a new way of detecting adulteration of virgin olive oils. [source] A simplified synthesis of 2,3,5,6-tetrafluorophenyl 2-(2-nitroimidazol-1-yl) acetateJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 6 2003Hanna Wilson Abstract 2,3,5,6-Tetrafluorophenyl 2-(2-nitroimidazol-1-yl) acetate has been synthesized via an improved route which involves the direct coupling of 2-(2-nitroimidazol-1-yl) acetic acid with 2,3,5,6-tetrafluorophenol. Copyright © 2003 John Wiley & Sons, Ltd. [source] Fiber introduction mass spectrometry: determination of pesticides in herbal infusions using a novel sol,gel PDMS/PVA fiber for solid-phase microextractionJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 6 2007Rogério Cesar da Silva Abstract An application of the direct coupling of solid-phase microextraction (SPME) with mass spectrometry (MS), a technique known as fiber introduction mass spectrometry (FIMS), is described to determine organochlorine (OCP) and organophosphorus (OPP) pesticides in herbal infusions of Passiflora L. A new fiber coated with a composite of poly(dimethylsiloxane) and poly(vinyl alcohol) (PDMS/PVA) was used. Sensitive, selective, simple and simultaneous quantification of several OCP and OPP was achieved by monitoring diagnostic fragment ions of m/z 266 (chlorothalonil), m/z 195 (,-endosulfan), m/z 278 (fenthion), m/z 263 (methyl parathion) and m/z 173 (malathion). Simple headspace SPME extraction (25 min) and fast FIMS detection (less than 40 s) of OCP and OPP from a highly complex herbal matrix provided good linearity with correlation coefficients of 0.991,0.999 for concentrations ranging from 10 to 140 ng ml,1 of each compound. Good accuracy (80 to 110%), precision (0.6,14.9%) and low limits of detection (0.3,3.9 ng ml,1) were also obtained. Even after 400 desorption cycles inside the ionization source of the mass spectrometer, no visible degradation of the novel PDMS/PVA fiber was detected, confirming its suitability for FIMS. Fast (ca 20 s) pesticide desorption occurs for the PDMS/PVA fiber owing to the small thickness of the film and its reduced water sorption. Copyright © 2007 John Wiley & Sons, Ltd. [source] Activity of the lactate,alanine shuttle is independent of glutamate,glutamine cycle activity in cerebellar neuronal,astrocytic culturesJOURNAL OF NEUROSCIENCE RESEARCH, Issue 1-2 2005Lasse K. Bak Abstract The glutamate,glutamine cycle describes the neuronal release of glutamate into the synaptic cleft, astrocytic uptake, and conversion into glutamine, followed by release for use as a neuronal glutamate precursor. This only explains the fate of the carbon atoms, however, and not that of the ammonia. Recently, a role for alanine has been proposed in transfer of ammonia between glutamatergic neurons and astrocytes, denoted the lactate,alanine shuttle (Waagepetersen et al. [ 2000] J. Neurochem. 75:471,479). The role of alanine in this context has been studied further using cerebellar neuronal cultures and corresponding neuronal,astrocytic cocultures. A superfusion paradigm was used to induce repetitively vesicular glutamate release by N -methyl- D -aspartate (NMDA) in the neurons, allowing the relative activity dependency of the lactate,alanine shuttle to be assessed. [15N]Alanine (0.2 mM), [2- 15N]/[5- 15N]glutamine (0.25 mM), and [15N]ammonia (0.3 mM) were used as precursors and cell extracts were analyzed by mass spectrometry. Labeling from [15N]alanine in glutamine, aspartate, and glutamate in cerebellar cocultures was independent of depolarization of the neurons. Employing glutamine with the amino group labeled ([2- 15N]glutamine) as the precursor, an activity-dependent increase in the labeling of both glutamate and aspartate (but not alanine) was observed in the cerebellar neurons. When the amide group of glutamine was labeled ([5- 15N]glutamine), no labeling could be detected in the analyzed metabolites. Altogether, the results of this study support the existence of the lactate,alanine shuttle and the associated glutamate,glutamine cycle. No direct coupling of the two shuttles was observed, however, and only the glutamate,glutamine cycle seemed activity dependent. © 2004 Wiley-Liss, Inc. [source] Numerical simulation of particle trajectory and atmospheric dispersion of airborne releasesMETEOROLOGICAL APPLICATIONS, Issue 3 2009S. Shoaib Raza Abstract Numerical simulation of particle trajectory and atmospheric dispersion has been performed for an airborne accidental release from a nuclear power plant site. A Long-range Particle transport and Dispersion Model (LPDM) based on a Lagrangian approach is developed and tested in this work. The Lagrangian transport/dispersion model is directly coupled with an atmospheric prediction model, RAMS (Regional Atmospheric Modeling System), to provide necessary meteorological fields in a three-dimensional domain. An advantage of this direct coupling is that the meteorological data generated by RAMS can be used directly for trajectory calculations without storage, thus reducing the CPU time consumed in the data storage and retrieval. This effort was done to be able to use this directly coupled modelling system for real-time predictions in case of an accidental release from a potential site. The simulated Lagrangian trajectories were compared with those obtained using observed hourly weather data obtained from an on-site meteorological tower. The results indicated that this one-way coupling between LPDM-RAMS provided almost identical trajectories when compared with those obtained using LPDM alone driven by hourly observed wind data. The comparison demonstrated the reliability of the RAMS meteorological predictions for the site under consideration. The comparison also indicated that LPDM (run in a stand alone mode), with hourly-observed wind data, could also be used for trajectory calculations over flat terrain. The model was developed on a parallel processing computer (SGI workstation, ORIGIN 2000 computer with eight processors) for use in real-time forecast mode. The computational time was about one-third of the simulation time, while using four processors. The model options need to be explored to reduce the computational time further and test its performance for real-time atmospheric dispersion applications. Copyright © 2009 Royal Meteorological Society [source] Efficient synthesis of conjugated alkynyl cycloalkenones: Pd(PPh3)4,AgOAc- catalyzed direct coupling of 1-alkynes with 3-oxocycloalkenyl triflatesAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 3 2010Chenggang Jiang Abstract Palladium,silver acetate-catalyzed cross coupling of vinyl triflates and 1-alkynes was investigated. This strategy offered a very straightforward and efficient method for access to conjugated alkynyl cycloalkenones from the conjugated vinyl triflates and 1-alkynes. Moreover, the triflates derived from 1,3-cycloalkadione needed no further purification and could be reacted immediately with 1-alkynes to provide the conjugated alkynyl cycloalkenones in excellent overall yields. Copyright © 2009 John Wiley & Sons, Ltd. [source] Asymmetric, Regioselective Direct Aldol Coupling of Enones and Aldehydes with Chiral Rhodium(bis-oxazolinylphenyl) CatalystsCHEMISTRY - A EUROPEAN JOURNAL, Issue 36 2009Masato Mizuno Boxing clever: A chiral rhodium(bis-oxazolinyl) complex 1 exhibited catalytic activity for the asymmetric, regioselective direct coupling of cyclic enones and aldehydes (see scheme). The products were obtained with high anti selectivity up to 97,% and with up to 94,%,ee. [source] UNRAVELLING THE PATHOPHYSIOLOGY OF COMPLEX REGIONAL PAIN SYNDROME: FOCUS ON SYMPATHETICALLY MAINTAINED PAINCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 7 2008Gael F Gibbs SUMMARY 1In diseases such as complex regional pain syndrome (CRPS), where neuropathic pain is the primary concern, traditional pain classifications and lesion descriptors are of limited value. To obtain better treatment outcomes for patients, the underlying pathophysiological mechanisms of neuropathic pain need to be elucidated and analysed so that therapeutic targets can be identified and specific treatments developed. 2In the present review, we examine the current literature on sympathetically maintained pain (SMP), a subset of neuropathic pain, within the context of CRPS. Evidence from both human and animal studies is presented and discussed in terms of its support for the existence of SMP and the mechanistic information it provides. 3We discuss three current hypotheses that propose both a site and method for sympathetic,sensory coupling: (i) direct coupling between sympathetic and sensory neurons in the dorsal root ganglion; (ii) chemical coupling between sympathetic and nociceptive neuron terminals in skin; and (iii) the development of a-adrenoceptor-mediated supersensitivity in nociceptive fibres in skin in association with the release of inflammatory mediators. 4Finally, we propose a new hypothesis that integrates the mechanisms of chemical coupling and a-adrenoceptor-mediated supersensitivity. This hypothesis is based on previously unpublished data from our laboratory showing that a histological substrate suitable for sympathetic,sensory coupling exists in normal subjects. In the diseased state, the nociceptive fibres implicated in this substrate may be activated by both endogenous and exogenous noradrenaline. The mediating a-adrenoceptors may be expressed on the nociceptive fibres or on closely associated support cells. [source] | |||||||||||||