bluuebunny/crossref_metadata_2025_split huggingface dataset:
Three‐Component Synthesis of Amine Derivatives Using Benzylic and Allylic Alcohols as N‐Alkylating Agents in the Absence of External Catalysts and Additives
Authors: Li Hai‐Hua , Dong De‐Jun , Tian Shi‐Kai 
Published: June 2008

AbstractThe direct employment of benzylic and allylic alcohols as N‐alkylating agents provides a useful synthetic route for amine derivatives by avoiding the preactivation of the hydroxy groups of alcohols. Herein we report a novel by‐product‐catalyzed three‐component synthesis of amine derivatives from readily available benzylic and allylic alcohols, acyl chlorides (chloroformates or sulfonyl chlorides), and hexamethyldisilazane (HMDS). In the absence of external catalysts and additives, a range of benzylic and allylic alcohols have been transformed into the corresponding N‐alkyl amides (carbamates or sulfonamides) in good to excellent yields. Furthermore, by‐product TMSCl and its decomposition into HCl have been found to be responsible for promoting the three‐component reaction of benzylic (or allylic) alcohols with acyl chlorides (chloroformates or sulfonyl chlorides) and HMDS.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Optimizing soluble protein extraction and two‐dimensional polyacrylamide gel electrophoresis quality for extremophile ciliates
Authors: Fulgentini Lorenzo , Marangoni Roberto , Colombetti Giuliano 
Published: June 2008

AbstractAn efficient protein extraction methodology is quite important for sample preparation and subsequent 2‐D PAGE and MS analysis. Cell lysis is the first step in protein extraction and purification. Many techniques are available for cell disruption, including physical and detergent‐based methods. Here, we report on a very fast and efficient detergent‐free Tris‐based method to extract the soluble fraction proteins of extremophile ciliates, comparing it with a detergent‐based protocol. This comparison has been carried out by means of 2‐D PAGE and subsequent MALDI‐compatible silver staining of protein samples obtained from the intensely pigmented hypersaline ciliate Fabrea salina and the Antarctic hypotrich ciliate Euplotes focardii. Our results indicate that this fast and easy extraction method allows to obtain more clear crude extracts and more spot‐abundant polyacrylamide gels.
Molecular‐Level Investigation of Critical Gap Size between Catalyst Particles and Electrolyte in Hydrogen Proton Exchange Membrane Fuel Cells
Authors: Liu J. , Cui S. , Keffer D. J. 
Published: June 2008

AbstractMolecular dynamics simulations have been performed to study the structure and transport at the electrode/electrolyte interface in hydrogen‐based proton exchange membrane fuel cells. We examine the wetting of catalyst surfaces that are not immediately adjacent to a Nafion membrane, but rather are separated from the membrane by a hydrophobic gap of carbon support surface (graphite). A mixture of Nafion, water and hydronium ions is able to wet small gaps (7.4 Å) of graphite and reach the catalyst surface, providing a path for proton transport from the catalyst to the membrane. However, for gaps of 14.8 Å, we observe no wetting of the graphite or the catalyst surface. Using a coarse‐grained model, we found that the presence of a graphite gap of 7.4 Å width slowed down the transport of water by at least an order of magnitude relative to a system with no gap. The implication is that catalyst particles that are not within nominally 1 nm of either the proton exchange membrane or recast ionomer in the electrode leading to the membrane do not possess a path for efficient proton transport to the membrane and consequently do not contribute significantly to power production in the fuel cell.
Brain derived neurotrophic factor Val66Met polymorphism, the five factor model of personality and hippocampal volume: Implications for depressive illness
Authors: Joffe Russell T. , Gatt Justine M. , Kemp Andrew H. , Grieve Stuart , Dobson‐Stone Carol , Kuan Stacey A. , Schofield Peter R. , Gordon Evian , Williams Leanne M. 
Published: June 2008

AbstractAltered hippocampal volume, the brain‐derived neurotrophic factor (BDNF) Val66Met polymorphism, and neuroticism have each been implicated in the etiology of psychiatric disorders, especially depression. However, the relationship between these variables is not well understood. Here, we determined the effects of the BDNF Val66met polymorphism on the five‐factor personality dimensions (assessed using the NEO‐FFI), trait depression (assessed with the DASS‐21) in a cross‐sectional cohort of 467 healthy volunteers. A large matched subset of this cohort was also assessed for grey matter volume of the hippocampus and contiguous temporal cortical regions using magnetic resonance imaging. In Met carriers, elevations in neuroticism and trait depression and stress were associated with lower mean hippocampal volume, but there were no such associations in Val homozygotes. Trait depression, in particular, was found to moderate the effects of BDNF genotypes on hippocampal volume. Met carriers with high trait depression showed a reduction in grey matter volume of the mean hippocampus compared with Val homozygotes. These findings suggest that even in otherwise healthy subjects, trait depression may contribute to the susceptibility of Met carriers to hippocampal grey matter loss. Hum Brain Mapp 2009. © 2008 Wiley‐Liss, Inc.
Influence of ocular filtering in EEG data on the assessment of drug‐induced effects on the brain
Authors: Romero Sergio , Mañanas Miguel A. , Barbanoj Manel J. 
Published: June 2008

AbstractOcular artifacts in EEG signals affect the interpretation of clinical study results. The aim of this study was to assess the influence of automatic ocular filtering procedures in the conclusions drawn from a pharmaco‐EEG trial. Regression analysis, gold standard, and blind source separation (BSS), Second Order Blind Identification algorithm, ocular filtering procedures were compared using time, frequency, topographic and tomographic brain mapping approaches and pharmacokinetic‐pharmacodynamic (PK‐PD) relationships. Data consisted of EEGs obtained from 20 volunteers who received single oral doses of haloperidol 3 mg, risperidone 1 mg, olanzapine 5 mg and placebo in a randomized cross‐over double‐blind design. Although the BSS‐based technique preserved brain activity more than regression analysis in anterior leads, in general, topographic significance probability maps globally showed similar results with both methods for most spectral variables. However, different results were obtained when using whole multi‐channel information for studying drug effects in the brain: (i) higher correlations between PK and PD time courses showing that BSS allowed estimation of spectral variables more accurately related to drug effects and (ii) larger and more symmetric drug related tomographic LORETA maps showing that BSS led to results that were more neurophysiopharmacologically sound. Definitely, the BSS‐based procedure is an effective and efficient preprocessing method to remove ocular artifacts from EEG data. The selection of the ocular filtering procedure could determine different results whose impact depends on the evaluating tool applied to analyze the pharmaco‐EEG data. Hum Brain Mapp 2009. © 2008 Wiley‐Liss, Inc.
Multiple repetitions reveal functionally and anatomically distinct patterns of hippocampal activity during continuous recognition memory
Authors: Johnson Jeffrey D. , Muftuler L. Tugan , Rugg Michael D. 
Published: June 2008

AbstractWe used a continuous recognition procedure that included multiple presentations of test items, along with high‐resolution functional magnetic resonance imaging (fMRI), to investigate the relationship between item novelty and recognition‐related activity in the medial temporal lobe (MTL). In several regions of hippocampus and parahippocampal cortex, activity elicited by new items exceeded that for old items, whereas no MTL regions exhibited greater activity for old items. Critically, anatomically distinct regions of MTL were engaged by item novelty in two different ways, as evidenced by statistically dissociable profiles of activity. In bilateral medial hippocampus and left posterior parahippocampal cortex, activity followed a categorical profile in which it was greater for new than old items but did not differ further with additional presentations of old items. By contrast, effects in adjacent regions of right lateral hippocampus and left parahippocampal cortex were graded, whereby activity declined linearly with respect to each successive item presentation. These findings suggest that the relationship between hippocampal (and parahippocampal) activity and continuous psychological dimensions, such as item novelty, cannot be captured by a unitary function. © 2008 Wiley‐Liss, Inc.
Local axon collaterals of area CA1 support spread of epileptiform discharges within CA1, but propagation is unidirectional
Authors: Orman R. , Von Gizycki H. , Lytton W.W. , Stewart M. 
Published: June 2008

AbstractCA3 and subiculum are hippocampal formation regions that can initiate seizure activity because each has a substantial intrinsic excitatory connectivity. We studied the intrinsic connectivity of area CA1 by exploring the spread of synchronous population discharges in ventral hippocampal slices from rats using a recording chamber that permitted multiple simultaneous extracellular recordings along all laminae of CA1. Brief single stimulus pulses were applied to stratum oriens (SO) or stratum radiatum (SR) on the CA3 side or the subicular side of CA1. In disinhibited slices, events triggered with SO or SR stimulation on the CA3‐side propagated over the proximo‐distal extent of CA1 with a maximal conduction velocity of 0.4 m/s, comparable with antidromic conduction velocities within CA1. By contrast, SO or SR stimuli applied on the subicular side of CA1 triggered events that did not spread “backward” toward CA3. These events are rapidly decremented in amplitude and duration. Whereas antidromic responses were largest when stimuli were applied on the subicular side of CA1, such responses were not sufficient to trigger epileptiform discharges when excitatory transmission was intact. We conclude that the unidirectional spread of epileptiform activity in area CA1 is the result of an intrinsic axon collateral system where each pyramidal cell has a proportionally larger projection toward subiculum. Although this collateral system is sparse compared with other hippocampal formation regions, its unidirectionality protects against re‐entrant activation of CA3 and may be physiologically significant as a relay from proximal CA1 to distal CA1. © 2008 Wiley‐Liss, Inc.
Modulation of long‐term potentiation by individual subtypes of muscarinic acetylcholine receptor in the rat dentate gyrus
Authors: Luo Le , Chen Wei‐Heng , Wang Ming , Zhu Da‐Miao , She Jia‐Qi , Ruan Di‐Yun 
Published: June 2008

AbstractThe roles of the muscarinic acetylcholine (ACh) receptors (mAChRs) in long‐term potentiation (LTP) at many areas of the central nervous system including the hippocampus, have been extensively studied. However, not much is known about the modulation of LTP through individual subtypes of mAChR (M1–M5 subtype). In this study, we investigated the involvement of each individual subtypes of mAChR in LTP induction by intrahippocampal administration of cholinergic ligands at the dentate gyrus (DG) of anesthetized rats. We found atropine, an antagonist of mAChRs, suppressed the induction of LTP. This observation confirmed that the muscarinic system is involved in LTP. We then examined the effects of M1AChR antagonists (pirenzepine and telenzepine), M2/4AChR antagonists (Methoctramine and {11‐[[2‐[(diethylamino)methyl]‐1‐piperidinyl]acetyl]‐5,11‐dihydro‐6H‐pyrido[2,3‐b][1,4]benzodiazepin‐6‐one}(AFDX‐116)), and M3/5AChR antagonist (4‐diphenylacetoxy‐N‐methylpiperidine methiodide (4‐DAMP)) on LTP. Our results showed that both M1AChR and M2/4AChR antagonists but not M3/5AChR antagonist suppressed the amplitude of LTP. We also examined the effects of these cholinergic ligands on basal synaptic transmission and found that only pirenzepine augmented the amplitude of population spike. This study suggests that individual mAChR subtypes play different modulation roles in LTP induction in the DG of rats. © 2008 Wiley‐Liss, Inc.
Combination regimen with statins and NSAIDs: A promising strategy for cancer chemoprevention
Authors: Xiao Hang , Yang Chung S. 
Published: June 2008

AbstractStatins and nonsteroidal antiinflammatory drugs (NSAIDs) are commonly prescribed for lowering cholesterol and antiinflammation, respectively. Recently, their potential roles as cancer chemopreventive agents have been subject to intensive studies. Human trials have not provided conclusive results on the protective effects of statins against different cancers, while more convincing results have been observed for cancer preventive effects of NSAIDs, especially on colorectal cancer. A promising strategy to enhance the cancer preventive efficacy of statins and NSAIDs is to use them in combination, which may produce synergy and lower the dose required for each agent. This strategy is of particular interest for potential use of low doses of statins and NSAIDs on a long‐term basis for cancer chemoprevention; increased risks for gastrointestinal and cardiovascular side effects associated with the use of NSAIDs have been observed in colorectal cancer chemopreventive trials. This article reviews the evidence for the cancer preventive actions of statins and NSAIDs, as well as their possible synergistic action and the mechanisms involved. © 2008 Wiley‐Liss, Inc.
Accurate redox potentials of mononuclear iron, manganese, and nickel model complexes*
Authors: Galstyan Artur , Knapp Ernst‐Walter 
Published: June 2008

AbstractDensity functional theory (DFT) was combined with solution of the Poisson equation for continuum dielectric media to compute accurate redox potentials for several mononuclear transition metal complexes (TMCs) involving iron, manganese, and nickel. Progress was achieved by altering the B3LYP DFT functional (B4(XQ3)LYP‐approach) and supplementing it with an empirical correction term GX having three additional adjustable parameters, which is applied after the quantum‐chemical DFT computations. This method was used to compute 58 redox potentials of 48 different TMCs involving different pairs of redox states solvated in both protic and aprotic solvents. For the 58 redox potentials the root mean square deviation (RMSD) from experimental values is 65 mV. The reliability of the present approach is also supported by the observation that the energetic order of the spin multiplicities of the electronic ground states is fulfilled for all studied TMCs, if the influence from the solvent is considered as well. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2009
Quantum chemical modeling of photoadsorption properties of the nitrogen‐vacancy point defect in diamond
Authors: Zyubin A. S. , Mebel A. M. , Hayashi M. , Chang H. C. , Lin S. H. 
Published: June 2008

AbstractQuantum chemical calculations of geometric and electronic structure and vertical transition energies for several low‐lying excited states of the neutral and negatively charged nitrogen‐vacancy point defect in diamond (NV0 and NV−) have been performed employing various theoretical methods and basis sets and using finite model NCnHm clusters. Unpaired electrons in the ground doublet state of NV0 and triplet state of NV− are found to be localized mainly on three carbon atoms around the vacancy and the electronic density on the nitrogen and rest of C atoms is only weakly disturbed. The lowest excited states involve different electronic distributions on molecular orbitals localized close to the vacancy and their wave functions exhibit a strong multireference character with significant contributions from diffuse functions. CASSCF calculations underestimate excitation energies for the anionic defect and overestimate those for the neutral system. The inclusion of dynamic electronic correlation at the CASPT2 level leads to a reasonable agreement (within 0.25 eV) of the calculated transition energy to the lowest excited state with experiment for both systems. Several excited states for NV− are found in the energy range of 2–3 eV, but only for the 13E and 53E states the excitation probabilities from the ground state are significant, with the first absorption band calculated at ∼1.9 eV and the second lying 0.8–1 eV higher in energy than the first one. For NV0, we predict the following order of electronic states: 12E (0.0), 12A2 (∼2.4 eV), 22E (2.7–2.8 eV), 12A1, 32E (∼3.2 eV and higher). © 2008 Wiley Periodicals, Inc. J Comput Chem 2009
Stratigraphy, pollen and 14C dating of Johnston's Gum Hole, a late Quaternary fossil kauri (Agathis australis) site, Northland, New Zealand
Authors: D'Costa D. M. , Palmer J. , Hogg A. , Turney C. , Fifield L. K. , Ogden J. 
Published: June 2008

AbstractJohnston's Gum Hole provides a discontinuous pollen record commencing late in Marine Isotope Stage 5 (MIS 5). In combination with other published records from the region, the Aupouri Peninsula is reconstructed to have been continuously forested through much of the last glacial cycle with the oscillation of Agathis‐ and Nothofagus‐dominated forest corresponding to stadials and interstadials, respectively. A northward latitudinal expansion of beech forest to 35° S is demonstrated. Kauri demise at the close of MIS 5 appears to have been due to flooding of the site. The elimination of kauri in MIS 3 was also associated with rewetting of the substrate, but could have been a more catastrophic event. The presence of both MIS 5 and MIS 3 kauri wood at the site suggests that other Aupouri peat swamps may also preserve timber of these ages, and demonstrate the potential of this area for providing MIS 3 and MIS 5 tree ring records. Copyright © 2008 John Wiley & Sons, Ltd.
Competitive affinity capillary electrophoresis assay based on a “hybrid” pre‐incubation/on‐capillary mixing format using an enantioselective aptamer as affinity ligand
Authors: Ruta Josephine , Ravelet Corinne , Baussane Isabelle , Fize Jennifer , Décout Jean‐Luc , Peyrin Eric 
Published: June 2008

AbstractIn this paper, we describe an aptamer‐based competitive affinity CE (ACE) assay involving (i) the pre‐incubation of the target (D‐arginine) and the specific ligand (anti‐D‐arginine‐L‐RNA aptamer) before (ii) the competition with the labeled target (dansylated D‐arginine) through an on‐capillary mixing strategy. The effects of some critical operating parameters such as the applied voltage and the sample‐aptamer mixture plug length on the assay sensitivity were investigated. The ACE assay appeared particularly dependent on the plug length of the pre‐incubated sample‐aptamer solution. It was shown that this “hybrid” strategy significantly improved the assay sensitivity relative to that obtained with a “full” on‐capillary mixing approach.
Selective determination of catechin, epicatechin and ascorbic acid in human urine using chiral capillary electrophoresis
Authors: El‐Hady Deia Abd , Gotti Roberto , El‐Maali Nagwa Abo 
Published: June 2008

AbstractChiral CE was successfully applied to the separation and quantification of catechin, epicatechin and ascorbic acid in some commercial drinks and human urine. Analysis involved the separation of analytes in less than 5.0 min at 240 nm with an untreated fused‐silica capillary under hydrodynamic injection mode. The running buffer consisted of 50 mM borate buffer with 3 mM β‐CD at pH 8.35. Detection limits for catechin, epicatechin and ascorbic acid were 0.028, 0.011 and 0.004 μg/mL, respectively. Linearity was investigated by selecting the ranges of calibration according to the amount of analytes in urine giving correlation coefficient percent (% r2) ranging between 99.4 and 99.6 at 99% confidence level. The maximum urinary excretion of catechin and epicatechin were noted at 2.0 and 4.0 h of the administrated dose. Unchanged catechin, epicatechin and ascorbic acid amounted to about 1.500, 8.696 and 0.003% of the administered dose in the 48.0 h urine collection. The proposed method achieved 99.2% completeness (n = 20) in urine media.
Experimental measurements and kinetic modeling of CO/H2/O2/NOx conversion at high pressure
Authors: Rasmussen Christian Lund , Hansen Jørn , Marshall Paul , Glarborg Peter 
Published: June 2008

AbstractThis paper presents results from lean CO/H2/O2/NOx oxidation experiments conducted at 20–100 bar and 600–900 K. The experiments were carried out in a new high‐pressure laminar flow reactor designed to conduct well‐defined experimental investigations of homogeneous gas phase chemistry at pressures and temperatures up to 100 bar and 925 K. The results have been interpreted in terms of an updated detailed chemical kinetic model, designed to operate also at high pressures. The model, describing H2/O2, CO/CO2, and NOx chemistry, is developed from a critical review of data for individual elementary reactions, with supplementary rate constants determined from ab initio CBS‐QB3 calculations. New or updated rate constants are proposed for important reactions, including OH + HO2 ⇋ H2O + O2, CO + OH ⇋ [HOCO] ⇋ CO2 + H, HOCO + OH ⇋ CO + H2O2, NO2 + H2 ⇋ HNO2 + H, NO2 + HO2 ⇋ HONO/HNO2 + O2, and HNO2(+M) ⇋ HONO(+M). Further validation of the model performance is obtained through comparisons with flow reactor experiments from the literature on the chemical systems H2/O2, H2/O2/NO2, and CO/H2O/O2 at 780–1100 K and 1–10 bar. Moreover, introduction of the reaction CO + H2O2 → HOCO + OH into the model yields an improved prediction, but no final resolution, to the recently debated syngas ignition delay problem compared to previous kinetic models. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 454–480, 2008
High‐frequency rTMS over the supplementary motor area for treatment of Parkinson's disease
Authors: Hamada Masashi , Ugawa Yoshikazu , Tsuji Sadatoshi 
Published: June 2008

AbstractDysfunction of the basal ganglia‐thalamocortical motor circuit is a fundamental model to account for motor symptoms in Parkinson's disease (PD). Using high‐frequency repetitive transcranial magnetic stimulation (rTMS) over the supplementary motor area (SMA), we investigated whether modulation of SMA excitability engenders therapeutic effects on motor symptoms in PD. In this double‐blind placebo‐controlled study, 99 patients were enrolled and assigned randomly to SMA‐stimulation and sham‐stimulation groups. For SMA stimulation, 20 trains of 50 transcranial magnetic stimuli at 5 Hz were delivered at an intensity of 110% active motor threshold for leg muscles in one session. The sham stimulation was 20 trains of electric stimuli given through electrodes fixed on the head to mimic the cutaneous sensation during rTMS. Each session of intervention was carried out once a week for the first 8 weeks. The SMA stimulation, in contrast to the sham stimulation, engendered significant improvements in total scores and motor scores of the Unified Parkinson's Disease Rating Scale. Mean improvements in motor scores were 4.5 points in the SMA‐stimulation group and −0.1 points in the sham‐stimulation group. Results indicate that 5 Hz rTMS over SMA modestly improves motor symptoms in PD patients; SMA is a potential stimulation site for PD treatment. © 2008 Movement Disorder Society