327 research outputs found

    Basis set effects on the electron density and spectroscopic properties of CO

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    The effect of basis set incompleteness on the deformation density of CO is studied by comparing various STO basis sets with a fully numerical (basis-free) result. A triple-zeta s, p basis plus one 3d and one 4f function appears to be practically converged. The convergence characteristics of other properties (Re, De, ωe, μ0, μ1, electric field gradient (EFG)) with respect to basis set size and type are also investigated. The convergence behaviour is similar for these properties and the deformation densities

    Resistivity due to low-symmetrical defects in metals

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    The impurity resistivity, also known as the residual resistivity, is calculated ab initio using multiple-scattering theory. The mean-free path is calculated by solving the Boltzmann equation iteratively. The resistivity due to low-symmetrical defects, such as an impurity-vacancy pair, is calculated for the FCC host metals Al and Ag and the BCC transition metal V. Commonly, 1/f noise is attributed to the motion of such defects in a diffusion process.Comment: 24 pages in REVTEX-preprint format, 10 Postscript figures. Phys. Rev. B, vol. 57 (1998), accepted for publicatio

    A review on equipment protection and system protection relay in power system

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    Power system equipment is configured and connected together with multiple voltage levels in existing electrical power system. There are varieties of electrical equipment obtainable in the power system predominantly from generation side up to the distribution side. Consequently, appropriate protections must be apt to prevent inessential disturbances that lead to voltage instability, voltage collapse and sooner a total blackout took place in the power system. The understanding of each component on the system protection is critical. This is due to any abnormal condition and failure can be analyzed and solved effectively due to the rapid changing and development on the power system network. Therefore, the enhancement of power quality can be achieved by sheltering the equipment with protection relay in power system. Moreover, the design of a systematic network is crucial for the system protection itself. Several types of protective equipment and protection techniques are taken into consideration in this paper. Hence, the existing accessible types and methods of system protection in the power system network are reviewed

    Ab initio simulations of liquid NaSn alloys: Zintl anions and network formation

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    Using the Car-Parrinello technique, ab initio molecular dynamics simulations are performed for liquid NaSn alloys in five different compositions (20, 40, 50, 57 and 80 % sodium). The obtained structure factors agree well with the data from neutron scattering experiments. The measured prepeak in the structure factor is reproduced qualitatively for most compositions. The calculated and measured positions of all peaks show the same trend as function of the composition.\\ The dynamic simulations also yield information about the formation and stability of Sn4_4 clusters (Zintl anions) in the liquid. In our simulations of compositions with 50 and 57 % sodium we observe the formation of networks of tin atoms. Thus, isolated tin clusters are not stable in such liquids. For the composition with 20 % tin only isolated atoms or dimers of tin appear, ``octet compounds'' of one Sn atom surrounded by 4 Na atoms are not observed.Comment: 12 pages, Latex, 3 Figures on reques

    Adsorption of CO on a Platinum (111) surface - a study within a four-component relativistic density functional approach

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    We report on results of a theoretical study of the adsorption process of a single carbon oxide molecule on a Platinum (111) surface. A four-component relativistic density functional method was applied to account for a proper description of the strong relativistic effects. A limited number of atoms in the framework of a cluster approach is used to describe the surface. Different adsorption sites are investigated. We found that CO is preferably adsorbed at the top position.Comment: 23 Pages with 4 figure

    Improved membranes for the extraction of heavy metals

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    This work presents a series of experimental tests on new practical approaches in membrane design to improve extraction capacity and rate. We chose an extraction system involving Aliquat 336 as the extractant and Cd(II) as the metal ion to be extracted to demonstrate these new approaches. The core element in the new membrane assembly was the extractant loaded sintered glass filter. This membrane assembly provided a large interface area between the extractant and the aqueous solution containing metal ions. By recycling the aqueous solution through the membrane assembly, the extraction rate was significantly improved. The membrane assembly also offered good extraction capacity

    Brain antibodies in the cortex and blood of people with schizophrenia and controls

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    The immune system is implicated in the pathogenesis of schizophrenia, with elevated proinflammatory cytokine mRNAs found in the brains of ~40% of individuals with the disorder. However, it is not clear if antibodies (specifically immunoglobulin-γ (IgG)) can be found in the brain of people with schizophrenia and if their abundance relates to brain inflammatory cytokine mRNA levels. Therefore, we investigated the localization and abundance of IgG in the frontal cortex of people with schizophrenia and controls, and the impact of proinflammatory cytokine status on IgG abundance in these groups. Brain IgGs were detected surrounding blood vessels in the human and non-human primate frontal cortex by immunohistochemistry. IgG levels did not differ significantly between schizophrenia cases and controls, or between schizophrenia cases in 'high' and 'low' proinflammatory cytokine subgroups. Consistent with the existence of IgG in the parenchyma of human brain, mRNA and protein of the IgG transporter (FcGRT) were present in the brain, and did not differ according to diagnosis or inflammatory status. Finally, brain-reactive antibody presence and abundance was investigated in the blood of living people. The plasma of living schizophrenia patients and healthy controls contained antibodies that displayed positive binding to Rhesus macaque cerebellar tissue, and the abundance of these antibodies was significantly lower in patients than controls. These findings suggest that antibodies in the brain and brain-reactive antibodies in the blood are present under normal circumstances.LJ Glass, D Sinclair, D Boerrigter, K Naude, SJ Fung, D Brown, VS Catts, P Tooney, M O’Donnell, R Lenroot, C Galletly, D Liu, TW Weickert and C Shannon Weicker

    Physical therapy in systemic sclerosis: the patient perspective

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    Objective: To assess the use, satisfaction, needs, and preferences regarding physical therapy (PT) in patients with systemic sclerosis (SSc). Methods: A total of 405 SSc patients, treated in the Leiden University Medical Center multidisciplinary care program and fulfilling American College of Rheumatology (ACR)/European Alliance of Associations for Rheumatology (EULAR) 2013 SSc criteria, received a questionnaire containing 37 questions on use and satisfaction regarding PT over a 2-year period, and their needs and preferences for future PT. Results: A total of 204 SSc patients (median age 63 years, 81% female) completed the questionnaire. One hundred twenty-eight patients (63%) had used or were using PT in a primary care setting. For 39% of patients not using PT, lack of referral or lack of knowledge was the reason for not using it. The most frequently reported active treatments were muscle-strengthening (n = 92 [72%]), range of motion (n = 77 [60%]), and aerobic exercises (n = 72 [56%]). Specific SSc hand- and mouth-opening exercises were reported by 20 (15%) and 7 (6%) patients, respectively. Manual treatment (massage or passive mobilization) was reported by 83 patients (65%). The mean ± SD satisfaction score (range 0–10) was 8.2 ± 1.6. Regarding patients' needs, 96 patients (47%) of the total group wanted to receive more information concerning PT, and 128 (63%) wanted to continue, start, or restart PT in the near future, with 56 of the 128 patients (44%) favoring individual treatment on a continuous basis. Conclusion: We observed a significant variation in the use and content of PT for SSc patients in a primary care setting. Our results suggest potential underuse of PT care, in particular for hand and oral dysfunction, and underpin the need for initiatives to improve the quality and accessibility of PT care for SSc patients

    cGMP becomes a drug target

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    Cyclic guanosine 3′,5′-monophosphate (cGMP) serves as a second messenger molecule, which regulates pleiotropic cellular functions in health and disease. cGMP is generated by particulate or soluble guanylyl cyclases upon stimulation with natriuretic peptides or nitric oxide, respectively. Furthermore, the cGMP concentration is modulated by cGMP-degrading phosphodiesterases. Several targets of cGMP are utilized to effect its various cellular functions. These effector molecules comprise cGMP-dependent protein kinases, ion channels, and phosphodiesterases. During the last decade, it emerged that cGMP is a novel drug target for the treatment of pulmonary and cardiovascular disorders. In this respect, several drugs were developed, which are now in clinical phase studies for, e.g., pulmonary hypertension or cardiovascular diseases. These new drugs act NO-independently with/without heme on soluble guanylyl cyclases or induce subtypes of particular guanylyl cyclases and thereby lead to new therapeutic concepts and horizons. In this regard, the fifth cGMP meeting held in June 2011 in Halle, Germany, comprised the new therapeutic challenges with the novel functional and structural concepts of cGMP generating and effector molecules. This report summarizes the new data on molecular mechanisms, (patho)physiological relevance, and therapeutic potentials of the cGMP signaling system that were presented at this meeting
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