Thiosemicarbazone derivatives of nickel and copper: the unprecedented coordination of furan ring in octahedral nickel(II) and of triphenylphosphine in three-coordinate copper(I) complexes

The influence of substituents at the C(2) carbon of N(1)-substituted thiosemicarbazones, {C(4)H(3)X-C(2)(CH(3))=N(3)-N(2)H-C(1)(=S)N(1)HR(2)} (X = O, S) on the geometry of nickel(ii) complexes has been investigated. The presence of a methyl group at the C(2) position of 2-acetylfuran-N(1)-substituted thiosemicarbazones {(C(4)H(3)O)-C(2)(CH(3))=N(3)-N(2)H-C(1)(=S)N(1)HR(2), R(2) = CH(3), HaftscN-Me; C(2)H(5), HaftscN-Et; C(6)H(5), HaftscN-Ph} induces unusual coordination by the furan ring and yielded high spin octahedral nickel(II) complexes, [Ni(κ(3)-O, N(3), S-aftscN-R(2))(2)], CH(3)1, C(2)H(5)2, and 2[Ni((κ(3)-O, N(3), S-aftscN-Ph)(2)] 3 (μ(eff) = 2.98, 1; 2.96, 2; 2.92, 3). With 2-acetylthiophene-N(1)-substituted thiosemicarbazones, {(C(4)H(3)S)-C(2)(CH(3))=N(3)-N(2)H-C(1)(=S)N(1)HR(2), R(2) = CH(3), HattscN-Me; C(2)H(5), HattscN-Et; C(6)H(5), HattscN-Ph}, N(3), S chelated low spin trans square planar complexes, {[Ni(κ(3)-O, N(3), S-attscN-R(2))(2)], R(2) = CH(3), 4; C(2)H(5), 5; C(6)H(5), 6} with pendant thiophene rings have been obtained. The bigger sized sulfur atoms of the thiophene rings form short intramolecular contacts with the deprotonated hydrazinic nitrogen atoms (SN(2)) inhibiting its lability for possible coordination to nickel(II). Complexes have one independent molecule (1) or two independent molecules (2, 3) in their respective crystal lattices. The simultaneous presence of methyl groups at the C(2) and N(1) atoms of 2-acetylthiophene-N(1)-methylthiosemicarbazone (HattscN-Me) have facilitated the binding of triphenylphosphine in three-coordinate copper(i) halide complexes, [CuX(η(1)-S-HattscN-Me)(Ph(3)P)] (X, Br, 7; Cl, 8), which represent an unusual donor set of ligands, namely, triphenylphosphine, sulfur of a thio-ligand and a halide.     

Characterization of volatile components of tea flowers (Camellia sinensis) growing in Kangra by GC/MS

Volatile flavour components of tea flowers (Camellia sinensis) were isolated by two methods viz. simultaneous distillation extraction (SDE), supercritical fluid extraction (SFE), analyzed by GC and GC/MS and compared with headspace analysis (HS). The composition of the volatile components extracted by the three methods differed considerably. In SFE, phenylethanol (14.7%), linalool (7.9%), (E)-linalool oxide furanoid (3.5%), epoxy linalool (1.6%), geraniol (2.3%) and hotrienol (1.5%) were major components. m-Xylene (2.6%), (E)-linalool oxide pyranoid (5.4%), p-myrcene (5.2%), alpha-cadinol (4.3%) and methyl palmitate (2.9%) were major compounds isolated by SDE. 3-hexenol (2.1%) (E)-4,8-dimethyl-1,3,7-nonatriene (20.9%) and linalool (35.1%) are major components in headspace analysis. Acetophenone and pheromone germacrene D is detected in tea flowers by all the methods studied. Floral, fresh and fruity odour of tea flowers is retained by SFE as there is very little loss of heat sensitive volatiles in SFE. The flavour isolated from SFE has superior quality compared to SDE.     

Onset of Darcy–Brinkman Ferroconvection in a Rotating Porous Layer Using a Thermal Non-Equilibrium Model: A Nonlinear Stability Analysis

This article presents a nonlinear stability analysis of a rotating thermoconvective magnetized ferrofluid layer confined between stress-free boundaries using a thermal non-equilibrium model by the energy method. The effect of interface heat transfer coefficient ( H^￠){( {{\mathcal H}^{\prime}})}, magnetic parameter (M ₃), Darcy–Brinkman number ( [^(D)]a){( {\hat{{\rm D}}{\rm a}})}, and porosity modified conductivity ratio (γ′) on the onset of convection in the presence of rotation (T_A1){({T_{{\rm A}_1}})} have been analyzed. The critical Rayleigh numbers predicted by energy method are smaller than those calculated by linear stability analysis and thus indicate the possibility of existence of subcritical instability region for ferrofluids. However, for non-ferrofluids stability and instability boundaries coincide. Asymptotic analysis for both small and large values of interface heat transfer coefficient (H^￠){({{\mathcal H}^{\prime}})} is also presented. A good agreement is found between the exact solutions and asymptotic solutions.     

A comparative study of vibrational dynamics of α- and β-forms of poly(β-hydroxybutyrate)

Normal modes and their dispersion are obtained for planar zig-zag form of poly(β-hydroxybutyrate) using Urey-Bradley force field. A comparison is made with the spectra of its helical form. Apart from detailed assignment of modes, various characteristic features of dispersion curves have been explained as arising due to internal symmetry in energy momentum space. The density-of-states have been used to calculate heat capacity in the temperature range 10-450 K using Debye's formalism.     

Multistep transitions in collagens

It is well known that collagens exist in triple-helical form, and, on average, the individual chains have glycine at every third place. Collagens from different sources vary in distributions of other amino acids. They could also be different in the distribution of defects, which are generally nonhelical regions of low stability. Varying lengths of individual chains in the triple-helical system can also contribute to this variability. All these variations manifest themselves in the creation of a transition profile with undulations that are indicative of a multiphasic nature. In the present communication, we try to understand this variability by using essentially the Zimm and Bragg approach and suitably amending it for a triple-helical system. Factors that contribute to the multiphasic nature are incorporated into the transition model and discussed. Results obtained for collagen types I, II, III, V_x, V_y, and XI are in agreement with the experimental measurements. Transitions in the first three types can be interpreted on the basis of two-phase theory. Nucleation parameters, which are indicative of the sharpness of transition, are interpreted in terms of stability and possible amino acid composition.     

Jamming transition of a two-dimensional traffic dynamics with consideration of optimal current difference

A modified two-dimensional lattice hydrodynamic traffic flow model is proposed by incorporating the optimal current difference effect of leading vehicles. Phase transitions and critical phenomenon are investigated near the critical point both analytically and numerically. Based on the configuration of vehicles, it is shown that two distinct jamming transitions occur: conventional jamming transition to the kink jam and jamming transition to the chaotic jam. It is shown that consideration of optimal current difference effect stabilizes the traffic flow and suppresses the traffic jam efficiently for all possible configurations of vehicles on a square lattice.     

Vibrational Dynamics of Poly(l-asparagine)

The normal modes and their dispersions for poly(l-asparagine) (PLN) in the α-helical form have been obtained in a reduced zone scheme with Wilson's GF matrix method as modified by Higgs. The results indicate that the modes below 1350 cm^?1 show appreciable dispersion. Optically active frequencies corresponding to the zone center and zone boundary are identified and discussed. Some of the characteristic features of the dispersion curves are repulsion accompanied by an exchange of character and von Hove singularities. Amide modes, side chain modes, and mixed modes are reported. The heat capacity calculated from the dispersion curves via density-of-states using Debye's relation is compared with the experimental data in the temperature range of 220–390 K.     

Analyses of the driver’s anticipation effect in a new lattice hydrodynamic traffic flow model with passing

In this paper, we studied the effect of driver’s anticipation with passing in a new lattice model. The effect of driver’s anticipation is examined through linear stability analysis and shown that the anticipation term can significantly enlarge the stability region on the phase diagram. Using nonlinear stability analysis, we obtained the range of passing constant for which kink soliton solution of mKdV equation exist. For smaller values of passing constant, uniform flow and kink jam phase are present on the phase diagram and jamming transition occurs between them. When passing constant is greater than the critical value depending on the anticipation coefficient, jamming transitions occur from uniform traffic flow to kink-bando traffic wave through chaotic phase with decreasing sensitivity. The theoretical findings are verified using numerical simulation which confirm that traffic jam can be suppressed efficiently by considering the anticipation effect in the new lattice model.     

Enzymatic transesterification of Jatropha curcas oil assisted by ultrasonication

Ultrasonication used for the production of fatty acid methyl ester from non-edible vegetable oil using immobilized lipase (Chromobacterium viscosum) as a catalyst from Enterobacter aerogenes to make the process fully ecologically and environmental friendly. The optimal conditions for biodiesel production is the molar ratio oil to methanol 1:4, catalyst concentration 5 wt.% of oil, reaction time 30 min, ultrasonic amplitude 50% (100 W/m(3)) and cycle 0.7s. ultrasonication reduce the reaction time comparing to the conventional batch process. The purity and conversion of the biodiesel was 84.5±0.5 analyzed by reversed phase HPLC.     

Incurred sample reanalysis in drug discovery bioanalysis

Bioanalysis plays a key role during the drug discovery process to generate the pharmacokinetic data to facilitate unbiased evaluation of leads, optimized leads and drug candidates. Such pharmacokinetic data are used to enable key decisions in the drug discovery process. The aim of the work is to put forward a new strategy of performing the incurred sample reanalysis for select small molecule novel chemical entities at different stages of drug discovery prior to candidate selection. Three discovery programs representing hits, leads and optimized lead candidates were selected for the incurred sample reanalysis (ISR) analysis. From each discovery program, two novel chemical entities were selected for the ISR analysis. The time points considered for ISR generally varied among the programs; however, samples coinciding with drug absorption, distribution and elimination were considered in the ISR assessment. With the exception of a single ISR value that gave a high deviation (about 63%), the observed ISR values supported the discovery bioanalytical assays. While the individual bioanalytical laboratory can draw an algorithm for selecting novel chemical entities and fixing the acceptance criteria for the ISR data, it is proposed that the percentage difference between ISR vs. original concentration for 67% of the repeat samples is contained within ±30% for discovery bioanalysis.