First-row transition metal doped germanium clusters Ge16M: some remarkable superhalogens.

A theoretical study of geometric and electronic structures, stability and magnetic properties of both neutral and anionic Ge16M0/- clusters with M being a first-row 3d transition metal atom, is performed using quantum chemical approaches. Both the isoelectronic Ge16Sc- anion and neutral Ge16Ti that have a perfect Frank-Kasper tetrahedral T d shape and an electron shell filled with 68 valence electrons, emerge as magic clusters with an enhanced thermodynamic stability. The latter can be rationalized by the simple Jellium model. Geometric distortions from the Frank-Kasper tetrahedron of Ge16M having more or less than 68 valence electrons can be understood by a Jahn-Teller effect. Remarkably, DFT calculations reveal that both neutral Ge16Sc and Ge16Cu can be considered as superhalogens as their electron affinities (≥3.6 eV) exceed the value of the halogen atoms and even that of icosahedral Al13. A detailed view of the magnetic behavior of Ge16M0/- clusters shows that the magnetic moments of the atomic metals remain large even when they are quenched upon doping. When M goes from Sc to Zn, the total spin magnetic moment of Ge16M0/- increases steadily and reaches the maximum value of 3 µ B with M = Mn before decreasing towards the end of the first-row 3d block metals. Furthermore, the IR spectra of some tetrahedral Ge16M are also predicted.

On the Inhibitability of Natural Products Isolated from Tetradium ruticarpum towards Tyrosine Phosphatase 1B (PTP1B) and α-Glucosidase (3W37): An In Vitro and In Silico Study.

Folk experiences suggest natural products in Tetradium ruticarpum can be effective inhibitors towards diabetes-related enzymes. The compounds were experimentally isolated, structurally elucidated, and tested in vitro for their inhibition effects on tyrosine phosphatase 1B (PTP1B) and α-glucosidase (3W37). Density functional theory and molecular docking techniques were utilized as computational methods to predict the stability of the ligands and simulate interaction between the studied inhibitory agents and the targeted proteins. Structural elucidation identifies two natural products: 2-heptyl-1-methylquinolin-4-one (1) and 3-[4-(4-methylhydroxy-2-butenyloxy)-phenyl]-2-propenol (2). In vitro study shows that the compounds (1 and 2) possess high potentiality for the inhibition of PTP1B (IC50 values of 24.3 ± 0.8, and 47.7 ± 1.1 µM) and α-glucosidase (IC50 values of 92.1 ± 0.8, and 167.4 ± 0.4 µM). DS values and the number of interactions obtained from docking simulation highly correlate with the experimental results yielded. Furthermore, in-depth analyses of the structure-activity relationship suggest significant contributions of amino acids Arg254 and Arg676 to the conformational distortion of PTP1B and 3W37 structures overall, thus leading to the deterioration of their enzymatic activity observed in assay-based experiments. This study encourages further investigations either to develop appropriate alternatives for diabetes treatment or to verify the role of amino acids Arg254 and Arg676.

An Integrated MCDM Model for Conveyor Equipment Evaluation and Selection in an FMC Based on a Fuzzy AHP and Fuzzy ARAS in the Presence of Vagueness.

The conveyor system plays a vital role in improving the performance of flexible manufacturing cells (FMCs). The conveyor selection problem involves the evaluation of a set of potential alternatives based on qualitative and quantitative criteria. This paper presents an integrated multi-criteria decision making (MCDM) model of a fuzzy AHP (analytic hierarchy process) and fuzzy ARAS (additive ratio assessment) for conveyor evaluation and selection. In this model, linguistic terms represented as triangular fuzzy numbers are used to quantify experts' uncertain assessments of alternatives with respect to the criteria. The fuzzy set is then integrated into the AHP to determine the weights of the criteria. Finally, a fuzzy ARAS is used to calculate the weights of the alternatives. To demonstrate the effectiveness of the proposed model, a case study is performed of a practical example, and the results obtained demonstrate practical potential for the implementation of FMCs.

An Integrated Approach of Fuzzy Linguistic Preference Based AHP and Fuzzy COPRAS for Machine Tool Evaluation.

Globalization of business and competitiveness in manufacturing has forced companies to improve their manufacturing facilities to respond to market requirements. Machine tool evaluation involves an essential decision using imprecise and vague information, and plays a major role to improve the productivity and flexibility in manufacturing. The aim of this study is to present an integrated approach for decision-making in machine tool selection. This paper is focused on the integration of a consistent fuzzy AHP (Analytic Hierarchy Process) and a fuzzy COmplex PRoportional ASsessment (COPRAS) for multi-attribute decision-making in selecting the most suitable machine tool. In this method, the fuzzy linguistic reference relation is integrated into AHP to handle the imprecise and vague information, and to simplify the data collection for the pair-wise comparison matrix of the AHP which determines the weights of attributes. The output of the fuzzy AHP is imported into the fuzzy COPRAS method for ranking alternatives through the closeness coefficient. Presentation of the proposed model application is provided by a numerical example based on the collection of data by questionnaire and from the literature. The results highlight the integration of the improved fuzzy AHP and the fuzzy COPRAS as a precise tool and provide effective multi-attribute decision-making for evaluating the machine tool in the uncertain environment.

Theoretical study on the reaction of the methylidyne radical, CH(X(2)Π), with formaldehyde, CH2O.

A theoretical study of the mechanism and kinetics of the CH(X(2)Π) + H2C═O reaction was carried out by ab initio molecular orbital theory based on the CCSD(T)/aug-cc-pVTZ//BHandHLYP/aug-cc-pVDZ method in conjunction with statistical theoretical kinetic VTST and RRKM Master Equation calculations. The potential energy surface for the cis/trans-HCOH + CH reactions was also examined. Calculated results show that the association reaction of CH and CH2O occurs by addition of the CH radical onto the oxygen atom, cycloaddition onto the C═O bond, and, for a small fraction, insertion of CH into a C-H bond, forming CH2C-O-CH, cyclic H2COCH, and CH2CHO, respectively. These channels are all barrierless, leading to a rate coefficient near the collision limit with a slight negative temperature dependence, in excellent agreement with experimental data. The intermediates can undergo extensive isomerization across seven C2H3O isomers, many with multiple conformers, prior to fragmentation. Eight fragmentation product sets were characterized, where H2CCO + H and CH3 + CO were found to be the major products at lower temperatures, while (3)CH2 + HCO started to contribute at higher temperatures. CCHO + H2, C2H + H2O, HCCOH + H, C2H2 + OH, and HCCO + H2 have negligible contributions for temperatures below 3000 K and pressures up to 100 atm. Collisional stabilization of the C2H3O isomers is negligible except at the highest of pressures and low temperatures.