Synthesis,Spectroscopic Characterization,and In Vitro Antimicrobial Potency of Sulfur-Bonded Complexes of Boron(III)

The present article describes the synthesis and characterization of tetracoordinated boron (III) complexes with monobasic bidentate ligands (L ¹ H, L ² H, L ³ H, L ⁴ H, L ⁵ H, and L ⁶ H) having the general formulae PhB(L)(OH) and PhB(L) ₂ . The 1:1 and 1:2 reactions of phenyl boronic acid with monobasic bidentate ligands resulted in the formation of colored solids. The complexes have been characterized by elemental analysis, molecular weight determinations, and IR and NMR ( ¹ H, ¹³ C and ¹¹ B) spectroscopy, as well as UV-vis spectral studies. Based on these studies, a tetrahedral geometry has been proposed for the resulting complexes. The ligands, along with their complexes, have been screened in vitro against a number of pathogenic fungal and bacterial strains. The studies indicate that the boron chelates are more potent than the parent ligands.     

Disjoining pressure and capillarity in the constrained vapor bubble heat transfer system

Using the disjoining pressure concept in a seminal paper, Derjaguin, Nerpin and Churaev demonstrated that isothermal liquid flow in a very thin film on the walls of a capillary tube enhances the rate of evaporation of moisture by several times. The objective of this review is to present the evolution of the use of Churaev's seminal research in the development of the Constrained Vapor Bubble (CVB) heat transfer system. In this non-isothermal "wickless heat pipe", liquid and vapor flow results from gradients in the intermolecular force field, which depend on the disjoining pressure, capillarity and temperature. A Kelvin-Clapeyron model allowed the use of the disjoining pressure to be expanded to describe non-isothermal heat, mass and momentum transport processes. The intermolecular force field described by the convenient disjoining pressure model is the boundary condition for "suction" and stability at the leading edge of the evaporating curved flow field. As demonstrated by the non-isothermal results, applications that depend on the characteristics of the evaporating meniscus are legion.     

A 2‐Tyr‐1‐carboxylate Mononuclear Iron Center Forms the Active Site of a Paracoccus Dimethylformamidase

N,N‐dimethyl formamide (DMF) is an extensively used organic solvent but is also a potent pollutant. Certain bacterial species from genera such as Paracoccus, Pseudomonas, and Alcaligenes have evolved to use DMF as a sole carbon and nitrogen source for growth via degradation by a dimethylformamidase (DMFase). We show that DMFase from Paracoccus sp. strain DMF is a halophilic and thermostable enzyme comprising a multimeric complex of the α₂β₂ or (α₂β₂)₂ type. One of the three domains of the large subunit and the small subunit are hitherto undescribed protein folds of unknown evolutionary origin. The active site consists of a mononuclear iron coordinated by two Tyr side‐chain phenolates and one carboxylate from Glu. The Fe³⁺ ion in the active site catalyzes the hydrolytic cleavage of the amide bond in DMF. Kinetic characterization reveals that the enzyme shows cooperativity between subunits, and mutagenesis and structural data provide clues to the catalytic mechanism.     

Design,synthesis and investigation of the interaction behavior between two acridone derivatives, 8-chloro acridone and nitrile cyanide acridone with calf thymus DNA,by different spectroscopic techniques

Journal of the Iranian Chemical Society - Evaluating the binding interaction between biomacromolecules and various chemical compounds is one of the most biologically researched topics. The present...     

Nonlinear Diameter Preserving Maps Between Certain Function Spaces

Let X, Y be compact Hausdorff spaces and A, B be subspaces of C(X) and C(Y), respectively, containing the constant functions such that B is point separating and the evaluation functionals are linearly independent on B. In this paper, we give the general form of a surjective, not assumed to be linear, diameter preserving map \({T:A \longrightarrow B}\) for the case where A is dense in C(X). Fixing a point \({x_1\in X}\), we show that there exist a subset \({Y_0}\) of Y, a scalar \({\beta\in \mathbb{T}}\), a bijective continuous map \({\Psi: Y_0 \longrightarrow X}\) and a constant function \({\alpha: Y_0 \longrightarrow \{-1,1\}}\) such that

$$\begin{aligned}T_{1} f(y) - T_{1} f(y_{1}) = & \beta ({\rm Re} (f(\Psi(y)) - f(\Psi(y_{1}))) \\ & + \alpha(y) i {\rm Im} (f(\Psi(y)) - f(\Psi(y_{1}))))\end{aligned}$$

for all \({f\in A}\) and \({y\in Y_0}\), where \({T_1=T-T0}\) and \({\Psi(y_1)=x_1}\). In particular, either

$$T_1(f)(y)=\beta f(\Psi(y))+L(f) \qquad (f\in A,y\in Y_0),$$

or

$$T_1(f)(y)=\beta \overline{f(\Psi(y))}+L(f) \qquad (f\in A, y\in Y_0),$$

holds for some functional L on A, which is linear (resp. real-linear) whenever T is so.

     

Subunit structure of glycinin and its molecular species based on RP-HPLC, gel electrophoresis and SEC studies

Glycinin and its molecular species (glycinin I and glycinin II) were separated and isolated. The number and kind of subunits of glycinin, glycinin I and glycinin II were determined. Studies were carried out under different experimental conditions using slab gel electrophoresis, size-exclusion chromatography and reversed-phase high performance liquid chromatography. Gel electrophoresis was done using both continuous and discontinuous system and under varying concentrations of resolving gel. In addition, the subunits were separated by reversed phase using gradient program. Glycinin and glycinin II were found to have 12 subunits each while glycinin I showed six subunits. Molecular weight and weight ratio in each case were also determined.     

Benzofuran-derived cyclic beta-amino acid scaffold for building a diverse set of flavonoid-like probes and the discovery of a cell motility inhibitor

We report here a practical, enantioselective synthesis of benzofuran-derived, cyclic trans-beta-amino acid scaffold. In two cases, tricyclic derivatives having six- and eight-membered unsaturated lactams were obtained from this versatile scaffold. To explore the biological applications, these compounds were subjected to cell-based assays, using NIH3T3 mouse cells to examine their potency as cell motility inhibitors and identified 18 as a potent cell motility inhibitor (IC50 approximately 40 microM in chamber cell migration assay).     

Polyaniline Langmuir-Blodgett film based cholesterol biosensor

Cholesterol oxidase (ChOx) has been covalently linked to Langmuir-Blodgett (LB) monolayers of polyaniline (PANI)-stearic acid (SA) prepared onto indium-tin-oxide (ITO) coated glass plates via glutaraldehyde (Glu) chemistry. These ChOx/Glu/PANI-SA LB film/ITO electrodes have been characterized by FT-IR, cyclic voltammetry, and scanning electron microscopy, respectively. The results of response measurements carried out on these bioelectrodes using linear sweep voltammetry (LSV) reveal linearity from 25 to 400 mg/dL of cholesterol concentration with sensitivity of 88.9 nA mg(-1) dL. The linear regression analysis of bioelectrode reveals standard deviation and correlation coefficient of 0.737 microA and 0.9988, respectively. The low value of the Michaelis-Menten constant of these bioelectrodes obtained as 1.21 mM for the immobilized enzyme indicates increased interaction between ChOx and cholesterol in the PANI-SA LB film.     

Premonitory effects near critical transition temperature in ordering systems – a Monte Carlo simulation

Premonitory effects manifest themselves in an ordering transition of the first kind (order) in the form of anomalously high short-range order (SRO) intensity at temperatures marginally above T _c, the critical transition temperature. This intensity located at the superlattice positions of the long-range ordered (LRO) phase is often attributed to the formation of ‘heterophase fluctuations’ resembling clusters of the LRO phase. Monte Carlo simulations in a hypothetical system showing FCC-to-L1₂ ordering transition have been carried out here to shed some light on this phenomenon and to look into the atomic configurations that make up these fluctuations.     

Ab initio study on the formation of chemically ordered Zr2Al phase by coupled replacive–displacive transformation

We performed plane wave-based first principles calculations using the projector augmented wave (PAW) potential under the generalized gradient approximation (GGA) within the density functional theory to study the formation of ordered omega (B8₂-structured) Zr₂Al phase in β-Zr₃Al alloy. The transformation involves both replacive and displacive processes. We investigated two possible paths for the transformation where steps involving replacive (diffusive) and displacive processes occur in succession with their sequence of occurrence being different in the two paths. From this study, it was possible to show that the initial chemical ordering facilitates the displacive process leading to the transformation. It was also possible to correlate instability with respect to omega-type displacements in Zr₂Al alloy with the number of Zr–Al bonds present in the unit cell. Electronic structure analysis indicated that stronger Zr–Al bonding plays an important role in the formation of chemically ordered omega phase.