Ruthenium monoterpyridine complexes with 2,6-bis(benzoxazol-2-yl)pyridine as an ancillary ligand: Synthesis,structure and spectral studies

Ruthenium monoterpyridine complexes, [1]⁺ and [2]²⁺, with 2,6-bis(benzoxazol-2-yl)pyridine as an ancillary ligand, L, have been synthesized and characterized by UV–Vis, FT-IR and ¹H NMR spectroscopic techniques. The formulations of the complexes were confirmed by the single crystal structure of their perchlorate salts. In both complexes, the Ru^II center is hexa-coordinated in a distorted geometry. In complex [1]⁺, the ancillary ligand L behaves as a bidentate ligand; in [2]²⁺, however, it binds the metal center as a tridentate ligand. The central pyridine nitrogen of terpyridine (N_p,trpy) is in a cis position with respect to the central pyridine nitrogen of the ancillary ligand (N_p,benz) in complex [1]⁺ and in a trans-position in complex [2]²⁺. The cis orientation of N_p,trpy and N_p,benz in complex [1]⁺ forces L to behave as bidentate. The quasi-reversible Ru^II/Ru^III couple appears at 0.90 and 1.44 V versus SCE in the case of complex [1]⁺ and [2]²⁺, respectively. [1]⁺, in the presence of aqueous AgNO₃, affords [2]²⁺ through an intramolecular dissociative interchange pathway.     

A novel ion selective sensor for promethium determination

This is a first promethium(145) ion-selective sensor based on the comparative study of two Schiff base ligands (X(1) and X(2)) as neutral ionophores. Effect of various plasticizers: 2-nitrophenyloctylether (o-NPOE), dibutyl phosphonate (DBP), dioctylphthalate (DOP), tri-(2-ethylhexyl) phosphate (TEHP), dibutyl butylphosphonate (DBBP), chloronaphthalene (CN) and anion excluders: potassium tetrakis (p-chloropheny1) borate (KTpClPB), sodiumtetraphenylborate (NaTPB) and oleic acid (OA) have been studied. The membrane with a composition of ionophore (X(1)/X(2)):KTpClPB:PVC:o-NPOE (w/w, %) in the ratio of 5:5:30:60 exhibited best performance. The best responsive membrane sensors (8 and 21) exhibited working concentration range of 4.5×10(-7)-1.0×10(-2) M and 3.5×10(-6)-1.0×10(-2) M with a detection limits of 3.2×10(-7) M and 2.3×10(-6) M and Nernstian slopes of 20.0±0.5, 19.5±0.5 mV decade(-1) of activity, respectively. The sensor no. 8 works satisfactorily in partially non-aqueous media up to 10% (v/v) content of methanol, ethanol and acetonitrile. Analytical application of the proposed sensor has been demonstrated in determination of promethium (III) ions in spiked water samples.     

2D Polarization Imaging of Turbid Media

Cancer normally tends to result in the decrease of tissue elasticity; i.e., the cancerous region is more rigid than the normal surrounding areas. This would appear as differences in the distribution of internal birefringence that could be used to improve image contrast between the cancerous and normal tissue structures. Different filtering techniques are used to enhance the image to help us identify, locate, and diagnose an “object,” such as a tumor inside a biological tissue.     

Optimization of Human Granulocyte Macrophage-Colony Stimulating Factor (hGM-CSF) Expression Using Asparaginase and Xylanase Gene’s Signal Sequences in <Emphasis Type="Italic">Escherichia coli</Emphasis>

The toxicity of the recombinant protein towards the expression host remains a significant deterrent for bioprocess development. In this study, the expression of human granulocyte macrophage-colony stimulating factor (hGM-CSF), which is known to be toxic to its host, was enhanced many folds using a combination of genetic and bioprocess strategies in Escherichia coli. The N terminus attachment of endoxylanase and asparaginase signal sequences from Bacillus subtilis and E. coli, respectively, in combination with and without His-tag, considerably improved expression levels. Induction and media optimization studies in shake flask cultures resulted in a maximal hGM-CSF concentration of 365 mg/L in the form of inclusion bodies (IBs) with a specific product yield (Y _P/X) of 120 mg/g dry cell weight in case of the asparaginase signal. Culturing the cells in nutrient rich Terrific broth maintained the specific product yields (Y _P/X) while a 6.6-fold higher volumetric concentration of both product and biomass was obtained. The purification and refolding steps were optimized resulting in a 95% pure protein with a fairly high refolding yield of 45%. The biological activity of the refolded protein was confirmed by a cell proliferation assay on hGM-CSF dependent human erythroleukemia TF-1 cells. This study demonstrated that this indeed is a viable route for the efficient production of hGM-CSF.     

Microscopic study of low-lying yrast spectra in <Superscript>100–108</Superscript>Mo isotopes

Variation-after-projection (VAP) calculations in conjunction with Hartree-Bogoliubov (HB) ansatz have been carried out for A=100−108 molybdenum (Mo) isotopes. In this framework, the yrast spectra with J _max ^π ≥10⁺, B(E2) transition probabilities, quadrupole (β₂) and hexadecapole (β₄) deformation parameters, moment of inertia (I) and square of cranking frequency (ω²) for even-even Mo isotopes have been obtained. The results of the calculation give an indication that it is important to include the hexadecapole-hexadecapole component of the two-body interaction for obtaining various nuclear structure quantities in these Mo isotopes.     

A microscopic study of deformation systematics in <Superscript>154–166</Superscript>Dy isotopes

The Hartree-Bogoliubov (HB) framework of calculations has been applied for calculating various nuclear structure quantities for ^154–166Dy mass chains. In this framework, the intrinsic quadrupole moments, the low-lying yrast states (E ₂⁺ and E ₄⁺) and occupation numbers for various shell model orbits have been obtained. The calculated results indicate that the observed onset of deformation in going from ¹⁵⁴Dy to ¹⁶⁶Dy arises due to enhanced occupation of (h _11/2)_π orbit, increased polarization of (d _5/2)_π orbit and increase in the occupation of down-slopping ‘k’ components of (i _13/2)_υ and (h _9/2)_υ orbits.      

Evolution of intrinsic nuclear structure in medium mass even-even Xenon isotopes from a microscopic perspective

In this study, the multi-quasiparticle triaxial projected shell model (TPSM) is applied to investigate \begin{document}$\gamma$\end{document}-vibrational bands in transitional nuclei of \begin{document}$^{118-128}{\rm{Xe}}$\end{document}. We report that each triaxial intrinsic state has a \begin{document}$\gamma$\end{document}-band built on it. The TPSM approach is evaluated by the comparison of TPSM results with available experimental data, which shows a satisfactory agreement. The energy ratios, B(E2) transition rates, and signature splitting of the \begin{document}$\gamma$\end{document}-vibrational band are calculated.     

Study of EIT resonances in an anti-relaxation coated Rb vapor cell

We study the sign of resonances obtained in electromagnetically induced transparency (EIT). Resonances of both kinds—bright (corresponding to enhanced absorption) and dark (corresponding to reduced absorption)—are obtained when the frequency of a probe beam is scanned. The experimental results, presented earlier, use magnetic sublevels of a hyperfine transition in the D₁ line of ⁸⁷Rb along with a magnetic field of 27 G. The atoms are contained in a vapor cell at room temperature, and with anti-relaxation coating on the walls. A quantitative theoretical model, which reproduces the experimental results quite well, is presented for the first time. The model solves the density matrix of the sublevels involved, and uses two regions—one with both the light and magnetic field, and the second without light and just a magnetic field. This ability to have both bright and dark resonances promises applications in sub- and super-luminal propagation of light.     

Mutants of Arabidopsis as Tools to Understand the Regulation of Phenylpropanoid Pathway and UVB Protection Mechanisms

Abstract— Plants accumulate certain phenylpropanoid compounds in the vacuoles of their epidermal and subepidermal cell layers thereby protecting the underlying tissue against UVB-induced damage. However, a number of mutants of Arabidopsis thaliana are known that fail to synthesize these protective pigments, thereby allowing harmful UVB radiation to penetrate into their dermal layers. Study of several of these nonlethal mutants, defective in various aspects of flavonoid and lignin biosynthesis, has led to a better understanding of the coordinate regulation and expression of important genes as well as of mechanisms involved in plant defense against UVB radiation. The characteristics of the various phenylpropanoid mutants of Arabidopsis, viz. flavonoid mutants (banyuls [ baity , increased chalcone synthase expression 1 [ icx1 ]; transparent testa [ tt ] and ultraviolet sensitive [ uvs ]) and hydroxycinnamic acid ester mutants (ferulic acid hydroxylase 1 [ fahl ] and sinapoylglucose accumulator 1 [ sng1 ]) are discussed in detail. We have briefly touched upon, wherever relevant, the unique aspects in other plant species too.     

Microarray immunoassay for thyrotropin on track-etched membranes using radiotracers

We report a microarray immunoassay for thyrotropin in serum using an anti-thyrotropin monoclonal ‘antibody-chip’ fabricated on polycarbonate track-etched membranes as a solid-support. The thyrotropin microarray immunoassay is an immunoradiometric assay using ¹²⁵I tracer and requires very small volumes of sample and reagents. The microarray immunoassay had the required minimum detection level, intra- and inter-assay CV and working range to be clinically useful. It correlated very significantly with commercial immunoradiometric assays for thyrotropin. We developed this microarray immunoassay for thyrotropin since it is often used as the first line test for thyroid function.