Processes of the solidification of Ni-B alloys

The temperature and concentration conditions of metastable phase formation in a Ni-B system at melt cooling rates of 10² to 10⁴ °C/s were investigated by X-ray structural analysis, metallography, and transmission electron microscopy. An increase in the cooling rate was shown to yield a decline in the concentration range of the metastable phase’s existence.     

A new synthesis of sultams from amino alcohols

The base-mediated cyclization of N,O-dimesylate derivatives of cyclic and acyclic amino alcohols provides a simple access to five- and six-member sultams: isothiazolidine-1,1-dioxides and thiazinane-1,1-dioxides respectively.     

High selective colorimetric detection of Cd<Superscript>2+</Superscript> ions using cysteamine functionalized gold nanoparticles with cross-linked DL-glyceraldehyde

This paper reports an ingenious colorimetric sensor probe for the detection of Cd²⁺ ions using cysteamine functionalized gold nanoparticles cross-linked with DL-glyceraldehyde (DL-G-CA-Au NPs). Rapid aggregation in DL-G-CA-Au NPs was observed by adding Cd²⁺ ions at PBS buffer pH 7.0, which results in an immediate color change of the solution from red to blue. A red-shift in the wavelength of absorption peak was measured from 520 to 736 nm using UV–visible spectroscopy. The surface functionalization and aggregation of Au NPs were also characterized by recoding FI-IR and DSL data. The colorimetric probe was analyzed in the concentration of Cd²⁺ ions ranging from 0.05 to 500 μM, and a good linearity was observed towards the lower concentration levels with a coefficient of correlation R ² = 0.9862. The limit of detection was found to be 21 nM, which best describes its superior performance over other reported colorimetric probes. Furthermore, the performance of the probe was not influenced by other metal ions, and the stability of DL-G-CA-Au NPs was maintained even after 30 days. The proposed method was successfully applied to various water samples collected from the environment, and an accuracy ≥ 98% was achieved.     

Ellipsometric and mechanical characterization of nanostructured anodic oxide film formed on Ti-6Al-7Nb alloy

In this work, we grow TiO₂ nanotube layers by using the single-step direct anodization of Ti-6Al-7Nb alloy in aqueous electrolytes containing F^? ions. Nanotube layers are characterized by spectroscopic ellipsometry (SE) and field-emission gun scanning electron microscopy (FEG-SEM). We also use SE to monitor the anodization process for TiO₂ nanotube layers on biocompatible Ti-6Al-7Nb alloy. In addition, we study mechanical properties by nanoindentation.     

Integrated production and maintenance planning for parallel machine system considering cost of rejection

Production scheduling and maintenance planning have interdependencies but been often considered and optimized independently in practice and in the literature. Furthermore, product quality has direct relationship with maintenance planning. This paper proposes an integrated approach for production scheduling and maintenance planning for parallel machine system considering the effect of cost of rejection. The approach aims to determine optimal production schedule and maintenance plan such that overall operations cost is minimized. A simulation-based optimization approach is used to solve the problem. A numerical investigation is performed to illustrate the approach. The integrated approach shows between 0.6 and 35.8% improvement in term of overall operations cost over independent approach for various scenarios. The results indicate that simultaneous consideration of production scheduling and maintenance planning results into better system performance.     

Oxidation of fullerene mixtures obtained by the electric arc evaporation of graphite rods

A mixture of stable derivatives of fullerenes containing ether/diketone functional groups, some of which are water-soluble, were obtained during the destruction of fullerenes upon annealing in air. The results were confirmed by IR and UV spectroscopy.     

An efficient synthesis of some new 3-bipyridinyl substituted coumarins as potent antimicrobial agents

As a part of the ongoing studies in developing new antimicrobials,a series of structurally novel 3- bipyridinyl substituted coumarin derivatives 4a-f and 5a-f were synthesized by a single-step reaction protocol under Krohnke’s reaction conditions.¹H NMR,¹³C NMR,IR and mass spectral techniques were employed for the structural elucidation of the synthesized compounds.An evaluation of antimicrobial activity showed that almost all compounds exhibited better results than the referenced drugs.Among the synthesized derivatives 4f,5a and 5d were found to be the most potent analogs.Thus they could be promising lead for novel drugs.     

Diethylamine: A smart organocatalyst in eco-safe and diastereoselective synthesis of medicinally privileged 2-amino-4H-chromenes at ambient temperature

Diethylamine has been demonstrated to be an efficient organocatalyst in the diastereoselective synthesis of Bcl-2 protein antagonist (HA-14-1) and of its structural analogues by one-pot condensation between salicylaldehyde and three different C–H acids, viz. ethyl cyanoacetate, phenylsulfonyl acetonitrile, and malononitrile. Easy commercial availability of the catalyst at extremely low cost and avoidance of conventional work-up as well as purification procedures qualifies this scalable protocol for a “near-ideal synthesis”.