A shape-optimization technique for the capillary surface problem

Summary The problem of the construction of an equilibrium surface taking the surface tension into account leads to Laplace-Young equation which is a nonlinear elliptic free-boundary problem. In contrast to Orr et al. where an iterative technique is used for direct solution of the equation for problems with simple geometry, we propose here an alternative approach based on shape optimization techniques. The shape of the domain of the liquid is varied to attain the optimality condition. Using optimal control theory to derive expressions for the gradient, a numerical scheme is proposed and simple model problems are solved to validate the scheme.     

A modified volumetric method for the estimation of streptomycin sulphate in pharmaceuticals

Summary A volumetric method for the estimation of streptomycin sulphate in pharmaceuticals is based on the quantitative discharge of the violet colour of the maltol-iron complex, produced when streptomycin is hydrolysed in alkaline medium and treated with ferric chloride, by potassium permanganate. It is simple, accurate and other antibiotics such as dihydrostreptomycin, sodium salt of benzyl penicillin, chloramphenicol do not interfere. Procain penicillin has to be separated by extractio with chloroform.

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Zusammenfassung Die beschriebene volumetrische Streptomycinbestimmung in Arzneimitteln beruht auf dem Abbau des Streptomycins in alkalischer Lösung zu Maltol, Bildung des Maltol-Eisen(III)-Komplexes und Titration mit Permanganat bis zur Entfärbung. Das Verfahren ist einfach auszuführen und gibt Werte von befriedigender Genauigkeit. Dihydrostreptomycin, Chloramphenicol sowie das Natriumsalz des Benzylpenicillins stören nicht. Procain-Penicillin muß vorher durch Extraktion mit Chloroform abgetrennt werden.

     

The interpretation of the Theory of Relativity

The presently accepted interpretation of the (Special) Theory of Relativity is considered by the author to be inadequate in certain respects. An alternative interpretation is suggested     

Design,Synthesis, and Anticancer Activity of Bis-isoxazole Incorporated Benzothiazole Derivatives

Russian Journal of General Chemistry - A novel series of bis-isoxazole incorporated benzothiazole derivatives has been designed and synthesized. Molecular structures of the compounds have been...     

Softlanding and STM imaging of Ag<Subscript> 561</Subscript> clusters on a C<Subscript> 60</Subscript> monolayer

The low energy deposition of silver cluster cations with 561 (±5) atoms on a cold fullerene covered gold surface has been studied both by scanning tunneling microscopy and molecular dynamics simulation. The special properties of the C₆₀/Au(111) surface result in a noticeable fixation of the clusters without a significant change of the cluster shape. Upon heating to room temperature we observe a flattening or shrinking of the cluster samples due to thermal activation. Similar changes were observed also for mass selected Ag clusters with other sizes. For comparison we also studied Ag islands of similar size, grown by low temperature deposition of Ag atoms and subsequent annealing. A completely different behavior is observed with much broader size distributions and a qualitatively different response to annealing.     

Efficient Synthesis of N‐Oxide Derivatives: Substituted 2‐(2‐(Pyridyl‐N‐oxide)methylsulphinyl)benzimidazoles

Different substituted 2‐chloromethylpyridyl derivatives (6a–d) were oxidized with mCPBA to give the respective 2‐chloromethylpyridine‐N‐oxide derivatives (7a–d) at low temperature, which on condensation with 2‐mercapto‐1H‐benzimidazole (8a–c) in the presence of aprotic solvents give the 2‐[[(pyridin‐2‐yl‐1‐oxide)methyl]sulfanyl]‐1H‐benzimidazole (9a–d) in good yield. Finally, 9a–d oxidized with mCPBA in chlorinated solvent gives a mixture of 2‐[[(pyridin‐2‐yl‐1‐oxide)methyl]sulfonyl]‐1H‐benzimidazole (3a–d, 10%) and 2‐[[(pyridin‐2‐yl‐1‐oxide) methyl]sulfinyl]‐1H‐benzimidazole (4a–d, 90%) derivatives.     

Green and ecofriendly synthesis of indole-condensed benzimidazole chalcones in water and their antimicrobial evaluations

An ecofriendly synthesis of novel benzimidazole-substituted indole derivatives catalyzed by ZnO nanoparticles has been developed from simple condensation of acetyl benzimidazole and indole-3-carbaldehyde followed by Michael addition of indoles. This ZnO Nano particles (NP)-catalyzed reaction has been carried out using both step-wise and one-pot methods, and both these methods provide excellent yield of product and less reaction time in water. All the synthesized compounds were characterized by Infrared spectroscopy (IR), Proton Nuclear Magnetic Resonance spectroscopy (Proton NMR), Carbon-13 Proton Nuclear Magnetic Resonance spectroscopy (¹³C-NMR), and mass analysis and screened for their antibacterial activity against clinical strains that include Gram-positive and Gram-negative bacteria.     

GC-MS,LC-MS/MS,Docking and Molecular Dynamics Approaches to Identify Potential SARS-CoV-2 3-Chymotrypsin-Like Protease Inhibitors from Zingiber officinale Roscoe

This study aims to identify and isolate the secondary metabolites of Zingiber officinale using GC-MS, preparative TLC, and LC-MS/MS methods, to evaluate the inhibitory potency on SARS-CoV-2 3 chymotrypsin-like protease enzyme, as well as to study the molecular interaction and stability by using docking and molecular dynamics simulations. GC-MS analysis suggested for the isolation of terpenoids compounds as major compounds on methanol extract of pseudostems and rhizomes. Isolation and LC-MS/MS analysis identified 5-hydro-7, 8, 2′-trimethoxyflavanone (9), (E)-hexadecyl-ferulate (1), isocyperol (2), N-isobutyl-(2E,4E)-octadecadienamide (3), and nootkatone (4) from the rhizome extract, as well as from the leaves extract with the absence of 9. Three known steroid compounds, i.e., spinasterone (7), spinasterol (8), and 24-methylcholesta-7-en-3β-on (6), were further identified from the pseudostem extract. Molecular docking showed that steroids compounds 7, 8, and 6 have lower predictive binding energies (MMGBSA) than other metabolites with binding energy of −87.91, −78.11, and −68.80 kcal/mole, respectively. Further characterization on the single isolated compound by NMR showed that 6 was identified and possessed 75% inhibitory activity on SARS-CoV-2 3CL protease enzyme that was slightly different with the positive control GC376 (77%). MD simulations showed the complex stability with compound 6 during 100 ns simulation time.