Docking and quantitative structure–activity relationship studies for sulfonyl hydrazides as inhibitors of cytosolic human branched-chain amino acid aminotransferase

We have performed the docking of sulfonyl hydrazides complexed with cytosolic branched-chain amino acid aminotransferase (BCATc) to study the orientations and preferred active conformations of these inhibitors. The study was conducted on a selected set of 20 compounds with variation in structure and activity. In addition, the predicted inhibitor concentration (IC₅₀) of the sulfonyl hydrazides as BCAT inhibitors were obtained by a quantitative structure–activity relationship (QSAR) method using three-dimensional (3D) vectors. We found that three-dimensional molecule representation of structures based on electron diffraction (3D-MoRSE) scheme contains the most relevant information related to the studied activity. The statistical parameters [cross-validate correlation coefficient (Q ² = 0.796) and fitted correlation coefficient (R ² = 0.899)] validated the quality of the 3D-MoRSE predictive model for 16 compounds. Additionally, this model adequately predicted four compounds that were not included in the training set.     

Contribution of superstring <Emphasis Type="Italic">Z</Emphasis>′ boson on the polarization effects in proton proton collisions

In this work we investigate the single- and the double-spin asymmetries at the collisions of polarized protons pp → (γ ^*, Z ⁰, Z′) + X within the scope of QCD, the electroweak interaction and superstring E ₆ theory. The helicity amplitude method is used. Analytical expressions for the single- and the double-spin asymmetries are obtained and their dependence on the transverse momentum of the lepton pair is investigated at the three different values of invariant masses of the lepton pair. The pure contribution coming from the superstring Z′ boson on the single- and double- spin asymmetries has been extracted. The results obtained allow investigation of the spin structure of the proton.     

ΛN Space-exchange effects in thes-shell hypernuclei and Λ 9 Be

Variational Monte Carlo calculations of the ground state separation energiesB _Λ of thes-shell hypernuclei and also of _Λ ⁹ Be have been made for an Urbana-type central space-exchange ΛN potential consistent with Λp scattering, and also including three-body ΛNN forces. Thes-shell hypernuclei are treated asA-body systems (A = baryon number), and _Λ ⁹ Be is analysed as a partially nine-body problem in the Λ — 2α model. The reduction ofB _Λ due to the space-exchange ΛN potential has been calculated for thes-shell hypernuclei for a range of interactions: both ΛN and ΛN + ΛNN forces. ForA = 3,4,5 the exchange energy is approximately, 0.04, 0.15 and 0.50 MeV, respectively. For _Λ ⁹ Be a much more limited study gives ≅ 1.3 MeV. These values are much larger than that for ‘soft’ ΛN +NN potentials when the correlations are weak. Preliminary results were presented at the DAE Symp. on ‘Nuclear Physics’ Vol. 32B (1989).     

Acute toxicities of six manufactured nanomaterial suspensions to Daphnia magna

The rapid growth of nanotechnology is stimulating research on the potential environmental impacts of manufactured nanomaterials (MNMs). This paper summarizes a comprehensive study on the 48-h acute toxicity of water suspensions of six MNMs (i.e., ZnO, TiO₂, Al₂O₃, C₆₀, SWCNTs, and MWCNTs) to Daphnia magna, using immobilization and mortality as toxicological endpoints. The results show that the acute toxicities of all MNMs tested are dose dependent. The EC₅₀ values for immobilization ranged from 0.622 mg/L (ZnO NPs) to 114.357 mg/L (Al₂O₃ NPs), while the LC₅₀ values for mortality ranged from 1.511 mg/L (ZnO NPs) to 162.392 mg/L (Al₂O₃ NPs). In these tests, TiO₂, Al₂O₃, and carbon-based nanomaterials were more toxic than their bulk counterparts. Moreover, D. magna were found to ingest nanomaterials from the test solutions through feeding behaviors, which indicates that the potential ecotoxicities and environmental health effects of these MNMs cannot be neglected.     

氢同位素氚水T2O(X1A1)的解析势能函数

获得T₂O(X¹A₁)解析势能函数的主要困难在于Born-Oppenheimer近似下T₂O(X¹A₁)与H₂O(X¹A₁)势能函数的不可区分性.然而,在Born-Oppenheimer近似下,分子势能函数实际上是键长、键角这些 关键词： 2O(X¹A₁)')" href="#">T₂O(X¹A₁) 同位素效应 解析势能函数     

QSAR modelling of the toxicity to Tetrahymena pyriformis by balance of correlations

Balance of correlations is an approach to build up quantitative structure–property/activity relationships (QSPR/QSAR). This approach is based on a split into the subtraining, calibration and test sets instead of classic split into training and test sets. The function of the calibration set is the preliminary check up of the model. In other words, the calibration set is like a preliminary test set. Computational experiments (with the Monte Carlo method) have shown that the statistical characteristics of the prediction for the toxicity to Tetrahymena pyriformis (the 50% growth inhibition concentration, IGC₅₀) based on the balance of correlations are better than the statistical characteristics of the prediction based on the classic scheme.     

A Novel RBF Neural Network Training Methodology to Predict Toxicity to Vibrio Fischeri

Summary This work introduces a neural network methodology for developing QSTR predictors of toxicity to Vibrio fischeri. The method adopts the Radial Basis Function (RBF) architecture and the fuzzy means training strategy, which is fast and repetitive, in contrast to most traditional training techniques. The data set that was utilized consisted of 39 organic compounds and their corresponding toxicity values to Vibrio fischeri, while lipophilicity, equalized electronegativity and one topological index were used to provide input information to the models. The performance and predictive ability of the RBF model were illustrated through external validation and various statistical tests. The proposed methodology can be used to successfully model toxicity to Vibrio fischerifor a heterogeneous set of compounds.     

A new force field for the adsorption of H2, O2, N2, CO,H2O,and H2S gases on alkali doped carbon nanotubes

The main goal of this work is the generation of a new force field data set to the interaction of several gases such as H₂, O₂, N₂, CO, H₂O, and H₂S with alkali cation-doped carbon nanotubes (CNTs) using ab initio calculations at the MP2(full)/6-311++G(d,p) level of theory. Different alkali cations including Li⁺, Na⁺_, K⁺ and Cs⁺ were used to dope in the CNT. The calculated potential energy curve for the interaction of each gas molecule with each alkali cation-doped CNTs was fitted to an analytical potential function to obtain the parameters of the potential function. A modified Morse potential function was selected for the fitting in which the electrostatic interactions has been accounted by adding the β/r term to the Morse potential. The accuracy of the calculated force field was checked via Grand Canonical Monte Carlo (GCMC) simulation of the H₂ adsorption on Li-doped graphite and Li-doped CNT. The results of these simulations were compared with the experimental measurements and the closeness of the simulation results with the experimental data indicated the accuracy of the proposed force field. The main merit of this work is the derivation of a specific force field for interaction of each of six gases with four alkali cation-doped CNT, which can be used in molecular simulation of these 24 of systems. The simulation results showed the increase of the H₂ adsorption capacity of nanotube and graphite up to 50% and 10%, respectively, due to the insertion of Li ions.