One Pot Regioselective Synthesis and Antimicrobial Studies of Some Novel Indazolyl–Thiazole Derivatives

2‐Benzylidene‐1‐tetralones, obtained via Claisen condensation of 1‐tetralones with aromatic aldehydes, in one pot condensation with thiosemicarbazide/semicarbazide and α‐haloketones in the presence of trifluoroethanol and conc. HCl gives rise to a series of new substituted‐3,3a,4,5‐tetrahydro‐2H‐benzo[g]indazol‐2yl‐thiazoles. The condensation was also carried out in two steps, and the intermediates 3‐substituted‐3,3a,4,5‐tetrahydro‐2H‐benzo[g]indazole‐2‐carbothioamides/carboxamides, obtained in the first step by the reaction of 2‐bezylidene‐1‐tetralones with thiosemicarbazide/semicarbazide, on reaction with α‐haloketones gives rise to indazolyl–thiazoles. A detailed X‐ray diffractometry of intermediate (3aR)‐3‐phenyl‐3,3a,4,5‐tetrahydro‐2H‐benzo[g]indazole‐2‐carbothioamide were carried out to establish its crystal structure. Further, density functional theory studies on (3aR)‐3‐phenyl‐3,3a,4,5‐tetrahydro‐2H‐benzo[g]indazole‐2‐carbothioamide and its regioisomer were carried out. There is good correlation between the theoretical and experimental spectral data. The antibacterial and antifungal activities of the selected compounds were examined, and some are found to exhibit excellent activities.     

Structural Properties of Cubic Sets in Regular LA-semihypergroups

In this article we characterize the regular LA-semihypergroups in terms of $({\in }_{\Gamma },{\in }_{\Gamma }\vee q_{\Delta })$-cubic (left, right, two sided, bi, generalized bi, interior, quasi)-hyperideals of LA-semihypergroups. Meanwhile, some illustrative examples are given to show the rationality of the definitions popularized in the present paper.     

Reactivity and selectivity in the inhibition of elastase by 3-oxo-beta-sultams and in their hydrolysis

3-oxo-beta-sultams are both beta-sultams and beta-lactams and are a novel class of time-dependent inhibitors of elastase. The inhibition involves formation of a covalent enzyme-inhibitor adduct with transient stability by acylation of the active-site serine resulting from substitution at the carbonyl centre of the 3-oxo-beta-sultam, C-N fission, and expulsion of the sulfonamide. The lead compound, N-benzyl-4,4-dimethyl-3-oxo-beta-sultam 1 is a reasonably potent inhibitor against porcine pancreatic elastase with a second-order rate constant of 768 M(-1) s(-1) at pH 6, but also possesses high chemical reactivity with a half-life for hydrolysis of only 6 mins at the same pH in water. Interestingly, the hydrolysis of 3-oxo-beta-sultams occurs at the sulfonyl centre with S-N fission and expulsion of the amide leaving group, whereas the enzyme reaction occurs at the acyl centre. Increasing selectivity between these two reactive centres was explored by examining the effect of substituents on the reactivity of 3-oxo-beta-sultam towards hydrolysis and enzyme inhibition. The inhibition activity against porcine pancreatic elastase has a much higher sensitivity to substituent variation than does the rate of alkaline hydrolysis. A difference of 2000-fold is observed in the second-order rate constants, k(i), for inhibition whereas there is only a 100-fold difference in the second-order rate constants, k(OH), for alkaline hydrolysis within the series. The higher sensitivity of enzyme inhibition to substituents than that of simple chemical reactivity indicates a significant degree of molecular recognition of the 3-oxo-beta-sultams by the enzyme.     

Antimicrobial and inhibition on heat-induced protein denaturation of constituents isolated from Polygonatum verticillatum rhizomes

This study was designed to assess the susceptibility of various microorganisms and inhibition on heat-induced protein denaturation against diosgenin and santonin, isolated from Polygonatum verticillatum rhizomes. Both diosgenin and santonin showed significant zone of inhibition when studied against various Gram-positive (Bacillus subtilis, Bacillus cereus, Staphylococcus aureus and Staphylococcus epidermidis) and Gram-negative bacteria (Escherichia coli and Salmonella typhi). In antifungal assay, only santonin exhibited profound sensitivity against various fungi (Aspergillus flavus, Aspergillus niger, Trichoderma harzianum and Fusarium oxysporum) used in the test. Both diosgenin and santonin also exhibited marked attenuation on heat-induced protein denaturation in a concentration-dependent manner with EC₅₀ values of 375 and 310 μg/mL, respectively. In conclusion, both the isolated compounds have antimicrobial potential supported by strong inhibition on protein denaturation and thus support the antimicrobial uses of plant in traditional system of treatment.     

High-yield synthesis of pure ZnO nanoparticles by one-step solid-state reaction approach for enhanced photocatalytic activity

Zinc oxide (ZnO) nanostructures were synthesized via a one-step solid-state reaction approach in ammonia (NH₃) gas environment with different temperature ramp rates. The so-formed nanostructures were characterized using X-ray diffraction (XRD) for phase identification, where the typical wurtzite hexagonal structure was observed. Scanning electron microscopy (SEM) confirmed the particle size to be in the range 45–50 nm, the same as calculated by the XRD pattern for the ramp rate of 10 °C/min. Energy dispersive X-ray (EDX) spectroscopy and X-ray photoelectron spectroscopy (XPS) confirmed the chemical purity of the samples. The photoluminescence (PL) spectrum indicated multiple near-band-edge emissions and energy-band emissions. Then, these ZnO nanomaterials were used for the degradation of crystal violet (CV) dye under UV light irradiation. The CV solution was completely degraded in 2 hr. The initial photocatalyst and dye amounts of 0.2 g/100 ml and 0.5 mg/L, respectively, were found to be the optimum values for maximum degradation efficiency. The ZnO-based photocatalyst was stable up to three cycles of reuse. These results indicate that the high surface area and porosity of the nanomaterials are responsible for the high efficiency, which was confirmed by specific surface area analysis.     

Phase transformation studies in unirradiated and proton beam irradiated Ni–Ti alloy between 25 and 100°C

The stress-induced phase transformation characteristics of unirradiated and proton beam irradiated NiTi alloy were investigated at different tests temperatures. The wire-shaped NiTi specimens were irradiated by 2?MeV proton beam for 30?min at room temperature to a flux of 10¹⁹ protons/m² s. Engineering stress–strain (S-S) curves of both unirradiated and irradiated specimens were obtained using a materials testing machine at 25, 50, 75 and 100°C. The results indicate a single-stage phase transformation from austenite to martensite (B2–B19′) in unirraidated specimens at all the test temperatures. In contrast, in the case of the irradiated specimens, a two-stage austenite–rhombohedral–martensite (B2–R–B19′) phase transformation is observed at 25 and 50°C. The B2–R–B19′ phase transformation, however, is found to change into B2–B19′ transformation at 75 and 100°C. The stress required to initiate the B19′ phase transformation (σ_MS) and the plateau range are found to be lower in irradiated specimens compared with those of the unirradiated specimens. The results obtained are discussed on the basis of the formation of Ni₄Ti₃ precipitates in irradiated specimens and their consequences on the phase transformations.     

Antihaemorrhagic potentials of Fagonia cretica against Naja naja karachiensis (black Pakistan cobra) venom

Plants have been extensively used as a remedy for the treatment of snake bites. The aim of this study was to determine the antivenom potentials of methanolic extract from the aerial parts (leaves and twigs) of Fagonia cretica L. on a haemorrhage induced by venom from Naja naja karachiensis. The haemorrhagic response of venom was dose dependent from 0.1 to 4.0?μg per 1.5?μL phosphate buffer saline (PBS) on vitelline veins of fertilised hens' eggs in their shells. The extract effectively eliminated and neutralised, in a dose-dependent manner, the haemorrhagic activity of snake venom. The minimum effective neutralising dose of F. cretica extract was found to be 15?μg per 1.5?μL PBS. The extract possesses potentials as haemorrhagic inhibitor against snake venom compared to the standard antiserum and various plants reported in the literature. This study also provides a scientific base for the use of F. cretica in traditional medicine for the treatment of snake bite.     

Polysulfonylamines. CXCI. The `almost' polymorphs rac‐trans‐2‐aminocyclohexan‐1‐aminium di(methanesulfonyl)azanide and its 0.11‐hydrate

The title compound, C₆H₁₅N₂⁺·C₂H₆NO₄S₂⁻, crystallizes as a 0.11‐hydrate, (I), in the space group C2; the asymmetric unit consists of two cations (one of each enantiomer), one anion on a general position, two half anions, each with the N atom on a twofold axis, and approximately one fifth of a water molecule. The general anion departs significantly from the usual conformation: it lacks one of the typical `W'‐shaped sequence of O—S—N—S—O atoms. The compound also crystallizes in the solvent‐free form, (II), in the space group P2₁/c, with one formula unit in the asymmetric unit. Both compounds form ribbons of hydrogen‐bonded cation dimers parallel to the b axis. In (I), there are two independent ribbons of opposite chirality, each involving one anion on a special position, and these ribbons are connected by hydrogen bonds to the anion on a general position, resulting in a layer structure parallel to (100). In (II), the chains are connected by hydrogen bonds, and again a layer structure parallel to (100) results.     

Finite element methods of an operator splitting applied to population balance equations

In population balance equations, the distribution of the entities depends not only on space and time but also on their own properties referred to as internal coordinates. The operator splitting method is used to transform the whole time-dependent problem into two unsteady subproblems of a smaller complexity. The first subproblem is a time-dependent convection-diffusion problem while the second one is a transient transport problem with pure advection. We use the backward Euler method to discretize the subproblems in time. Since the first problem is convection-dominated, the local projection method is applied as stabilization in space. The transport problem in the one-dimensional internal coordinate is solved by a discontinuous Galerkin method. The unconditional stability of the method will be presented. Optimal error estimates are given. Numerical tests confirm the theoretical results.     

Synthesis and characterization of some bis(cyclopentadienyl)titanium(IV) complexes with internally functionalized oximes(LH): sol–gel transformations of Cp2TiCl2, Cp2TiClL and Cp2TiL2 to nano‐sized anatase titania

Some bis(cyclopentadienyl)titanium(IV) complexes of the type [Cp₂TiCl_2?n{L}_n] {where, n = 1 or 2; L = ONC(R)Ar; R = H or CH₃ and Ar = C₅H₄N‐2, C₄H₃O‐2 or C₄H₃S‐2} have been synthesized by the metathetical reactions of Cp₂TiCl₂ with the sodium salt of internally functionalized oximes in 1:1 and 1:2 stoichiometry in anhydrous THF. All these red to brown colored solid derivatives have been characterized by elemental analyses, FT‐IR and NMR (¹H and ¹³C{¹H}) spectral studies. The FAB mass spectra of some representative derivatives indicate their monomeric nature. Oximato ligands in all the complexes appear to bind the titanium via N and O in a dihapto ( ‐N, O) manner in the solid state. Thermogravimetric curves of [Cp₂TiCl{ONC(CH₃)C₅H₄N‐2}] and [Cp₂Ti{ONC(CH₃)C₅H₄N‐2}₂] suggest the formation of hybrid materials CpTiO(Cl) and Cp₂TiO, respectively, as the final products at 900 °C under nitrogen atmosphere. Sol–gel transformations of Cp₂TiCl₂, [Cp₂TiCl{ONC(CH₃)C₅H₄N‐2}] and [Cp₂Ti{ONC(CH₃)C₅H₄N‐2}₂] yielded titania a–c, respectively, at low sintering temperature (600 °C). The powder XRD patterns, IR as well as Raman spectra of all these oxides indicate the formation of nano‐sized anatase phase. The SEM images of titania a–c indicate agglomers like surface morphologies. The absorption spectra of a–c exhibit an energy band gap in the range of 3.47–3.71 eV. Copyright © 2011 John Wiley & Sons, Ltd.