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31.
32.
We present a new molecular dynamics method for studying the dynamics of open systems. The method couples a classical system to a chemical potential reservior. In the formulation, following the extended system dynamics approach, we introduce a variable, v to represent the coupling to the chemical potential reservoir. The new variable governs the dynamics of the variation of number of particles in the system. The number of particles is determined by taking the integer part of v. The fractional part of the new variable is used to scale the potential energy and the kinetic energy of an additional particle: i.e., we introduce a fractional particle. We give the ansatz Lagrangians and equations of motion for both the isothermal and the adiabatic forms of grand molecular dynamics. The averages calculated over the trajectories generated by these equations of motion represent the classical grand canonical ensemble (μVT) and the constant chemical potential adiabatic ensemble (μVL) averages, respectively. The microcanonical phase space densities of the adiabatic and isothermal forms the molecular dynamics method are shown to be equivalent to adiabatic constant chemical potential ensemble, and grand canonical ensemble partition functions. We also discuss the extension to multi-component systems, molecular fluids, ionic solutions and the problems and solutions associated with the implementation of the method. The statistical expressions for thermodynamic functions such as specific heat; adiabatic bulk modulus, Grüneissen parameter and number fluctuations are derived. These expressions are used to analyse trajectories of constant chemical potential systems. 相似文献
33.
Duygu İnci Özgür Vatan Yunus Zorlu Nilüfer Çinkılıç 《Journal of biomolecular structure & dynamics》2013,31(15):3878-3901
New binary copper(II) complexes – [Cu(4-mphen)2(NO3)]NO3·H2O (1), [Cu(5-mphen)2 (NO3)]NO3·H2O (2), the known complex [Cu(dmphen)2(NO3)]NO3 (3) and [Cu(tmphen)2 (NO3)]NO3·H2O (4) - (4-mphen: 4-methyl-1,10-phenanthroline, 5-mphen: 5-methyl-1,10-phenanthroline, dmphen: 4,7-dimethyl-1,10-phenanthroline, tmphen: 3,4,7,8-tetramethyl-1,10-phenanthroline), have been synthesized and characterized by CHN analysis, ESI-MS, FTIR and single-crystal X-ray diffraction techniques. Interaction of these complexes with calf thymus DNA (CT-DNA) has been investigated by absorption spectral titration, ethidium bromide (EB) and Hoechst 33,258 displacement assay and thermal denaturation measurement. These complexes cleaved pUC19 plasmid DNA in the absence and presence of an external agent. Notably, in the presence of H2O2 as an activator, the cleavage abilities of these complexes are obviously enhanced at low concentration. Addition of hydroxyl radical scavengers like DMSO shows significant inhibition of the DNA cleavage activity of these complexes. BSA quenching mechanism was investigated with regard to the type of quenching, binding constant, number of binding locations and the thermodynamic parameters. The experimental results suggested that the probable quenching mechanism was an unusual static process and hydrophobic forces play a dominant role. The CT-DNA and BSA binding efficiencies of these complexes follow the order: 4 > 3 > 1 > 2. Furthermore, in vitro cytotoxicities of these complexes on tumor cells lines (Caco-2, MCF-7 and A549) and healthy cell line (BEAS-2B) showed that these complexes exhibited anticancer activity with low IC50 values. The effect of hydrophobicity of the methyl-substituted phenanthrolines on DNA and protein binding activities of these complexes is discussed. 相似文献
34.
Dr Burak GüÇlü George A. Gescheider Stanley J. Bolanowski Yorgo İstefanopulos 《Somatosensory & motor research》2013,30(4):239-253
A computational model based on previous physiological and psychophysical data is presented for the human Pacinian (P) psychophysical channel. The model can predict the probability of detection in simple psychophysical tasks, and hence psychometric functions and thresholds. The model simulates stimulating variable and fixed glabrous skin sites with different-sized contactors and includes spatial variation of monkey P-fiber sensitivities. Therefore, it is especially suitable for studying spatial summation, i.e. the improvement of threshold with increasing contactor area. Selective contributions of neural integration (n.i.) and probability summation (p.s.) are also incorporated into the model. Model predictions are compared to psychophysical results of Gescheider et al. (). The performance of the model regarding the effects of contactor size is very good. In addition to predicting approximately 3?dB improvement of thresholds when the contactor area is doubled, the model also reveals nonlinear contributions of p.s. and n.i. Furthermore, the model asserts that thresholds are largely governed by neural integration when small contactors are used. These and other findings discussed in the article show that the presented model is a helpful tool for formulating testable hypotheses. Although the model can also simulate some temporal summation effects, simulation results do not conform well to previous data on temporal response properties. Thus, the model needs to be refined in that respect. 相似文献
35.
DANIEL TRAN TAKASHI KADONO MARIA LIA MOLAS RAFIK ERRAKHI JOËL BRIAND BERNADETTE BILIGUI TOMONORI KAWANO FRANÇOIS BOUTEAU 《Plant, cell & environment》2013,36(3):569-578
Ozone (O3) is an air pollutant with an impact increasingly important in our industrialized world. It affects human health and productivity in various crops. We provide the evidences that treatment of Arabidopsis thaliana with O3 results in ascorbate‐derived oxalic acid production. Using cultured cells of A. thaliana as a model, here we further showed that oxalic acid induces activation of anion channels that trigger depolarization of the cell, increase in cytosolic Ca2+ concentration, generation of reactive oxygen species and cell death. We confirmed that O3 reacts with ascorbate in the culture, thus resulting in production of oxalic acid and this could be part of the O3‐induced signalling pathways that trigger programmed cell death. 相似文献
36.
AGATHE COURTEILLE GILLES INNOCENTI FRANÇOISE EYMERY DOMINIQUE RUMEAU EMMANUELLE ISSAKIDIS‐BOURGUET PASCAL REY 《Plant, cell & environment》2013,36(3):670-682
Methionine (Met) in proteins can be oxidized to two diastereoisomers of methionine sulfoxide, Met‐S‐O and Met‐R‐O, which are reduced back to Met by two types of methionine sulfoxide reductases (MSRs), A and B, respectively. MSRs are generally supplied with reducing power by thioredoxins. Plants are characterized by a large number of thioredoxin isoforms, but those providing electrons to MSRs in vivo are not known. Three MSR isoforms, MSRA4, MSRB1 and MSRB2, are present in Arabidopsis thaliana chloroplasts. Under conditions of high light and long photoperiod, plants knockdown for each plastidial MSR type or for both display reduced growth. In contrast, overexpression of plastidial MSRBs is not associated with beneficial effects in terms of growth under high light. To identify the physiological reductants for plastidial MSRs, we analyzed a series of mutants deficient for thioredoxins f, m, x or y. We show that mutant lines lacking both thioredoxins y1 and y2 or only thioredoxin y2 specifically display a significantly reduced leaf MSR capacity (–25%) and growth characteristics under high light, related to those of plants lacking plastidial MSRs. We propose that thioredoxin y2 plays a physiological function in protein repair mechanisms as an electron donor to plastidial MSRs in photosynthetic organs. 相似文献
37.
38.
George A. Gescheider Burak GüÇlü Jessica L. Sexton Sarah Karalunas Anne Fontana 《Somatosensory & motor research》2013,30(4):255-268
Psychophysical thresholds for the detection of a 300-Hz burst of vibration applied to the thenar eminence were measured for stimuli applied to the skin through 1.5?cm2 and through 0.05?cm2 contactors. Thresholds were approximately 13?dB lower when the area of the contactor was 1.5?cm2 than when it was 0.05?cm2. The difference between the thresholds measured with the large and small contactors was significantly reduced when only the lowest thresholds obtained in the testing sessions were considered. This result supports the hypothesis that one component of spatial summation in the P channel is probability summation. In addition, threshold measurements within a session were less variable when measured with the 1.5?cm2 contactor. We conclude that spatial summation in the P channel is a joint function of two processes that occur as the areal extent of the stimulus increases: probability summation in which the probability of exceeding the psychophysical detection threshold increases as the number of receptors of varying sensitivities increases, and neural integration in which neural activity originating from separate receptors is combined within the central nervous system rendering the channel more sensitive to the stimulus. 相似文献
39.
The question of Kurdish language rights has been a central issue in the Turkish–Kurdish conflict. The current study examined endorsement of Kurdish language rights in relation to intergroup factors (i.e. group identifications, cross-group friendships, perceived discrimination, and perceived out-group beliefs about state unity) among self-identified Turkish and Kurdish participants. The results indicate that Turks were much less in favour of these rights than the Kurds. In addition, for the Turks, higher national and ethnic identification were associated with lower support for Kurdish language rights, while cross-group friendship, perceived discrimination of Kurds and the belief that Kurds endorse national unity were associated with more support for rights. For the Kurdish participants, stronger national identification seems to undermine the mobilizing meaning that Kurdish group identification has for language rights support. Furthermore, friendship with Turks can undermine the support for rights because it strengthens national identification and reduces ethnic identification. 相似文献
40.
Ramin Ekhteiari Salmas Mert Mestanoglu Elif Çelenk Kaya 《Journal of enzyme inhibition and medicinal chemistry》2016,31(1):31-37
A series of hydroxy and phenolic compounds have been assayed for the inhibition of two physiologically relevant carbonic anhydrase (CA, EC 4.2.1.1) isozymes, the cytosolic human isozymes I and II. The investigated molecules showed inhibition constants in the range of 1.07–4003 and 0.09–31.5?μM at the hCA I and hCA II enzymes, respectively. In order to investigate the binding mechanisms of these inhibitors, in silico studies were also applied. Molecular docking scores of the studied compounds are compared using three different scoring algorithms, namely Glide/SP, Glide/XP and Glide/IFD. In addition, different ADME (absorption, distribution, metabolism and excretion) analysis was performed. All the examined compounds were found within the acceptable range of pharmacokinetic profiles. 相似文献