A comparison of different powder compaction processes adopted for synthesis of lead-free piezoelectric ceramics

Barium zirconium titanate, Ba(Zr_0.15Ti_0.85)O₃ nano-crystalline powders were synthesized using highenergy ball milling. The calcined powders were compacted adopting two different approachesviz. the conventional uniaxial pressing and cold-isostatic pressing (CIP) and the compactswere sintered at 1350 °C. Asingle phase perovskite structure was observed in both cases. BZT ceramics compacted usingCIP technique exhibited enhanced dielectric and ferroelectric properties compared toceramics compacted by uniaxial pressing. The polarization current peaks have been used inthis paper as an experimental evidence to prove the existence of ferroelectricity in theBZT ceramics under study. The peak polarization current was found to be ~700% higher in case of coldiso-statically compacted ceramics. Similarly electric field induces strain showed amaximum strain (S_max) of 0.08% at an electric fieldof 28 kV/cm. The dielectric and ferroelectric properties observed are comparable to singlecrystals of the same material.     

Enantioselective synthesis of (-)-pentalenene

A short, enantioselective synthesis of (-)-pentalenene is described. Catalytic enantioselective cyclopropenation with (R,R)-Rh2(OAc)(DPTI)3 was used to set the absolute stereochemistry, and an intramolecular Pauson-Khand reaction of the resulting cyclopropenyne was used to establish the quaternary center.     

The binding of nitric oxide at the Cu(i) site of copper nitrite reductase and of inorganic models: DFT calculations of the energetics and EPR parameters of side-on and end-on structures

Density functional theory calculations have been used to probe the end-on and side-on bonding motifs of nitric oxide at the Cu(i) centre in the enzyme copper nitrite reductase and in three inorganic model systems. We find that irrespective of a range of functionals used, the end-on structure is preferred by up to 40 kJ mol(-1), although this preference is smaller for the enzyme than for the inorganic model systems. We have calculated the g-tensor and atomic hyperfine coupling constants for these structures. When compared to available experimental data, for one model compound the calculated EPR parameters definitely favour an end-on structure, although this preference is somewhat less for the enzyme. Our prediction of NO end-on binding in the enzyme is at variance with structural data.     

Fragmentation of nitrone triflates to 9-membered rings

A new fragmentative rearrangement of nitrone derivatives to form 9-membered rings is reported. The fragmentations are triggered when nitrones are treated with triflic anhydride; a C-C bond antiperiplanar to the cleaving N-O bond is activated either by an oxygen lone pair or by an electron-rich aromatic ring. In the former case, further cyclization of the 9-membered intermediate leads to a rearranged condensed ring system, but when triggered by arenes, 9-membered ring amides are isolated.     

O6-(benzotriazol-1-yl)inosine derivatives: easily synthesized, reactive nucleosides

A novel class of O6-(benzotriazol-1-yl)inosine as well as the corresponding 2'-deoxy derivatives can be conveniently prepared by a reaction between sugar-protected or -unprotected inosine or 2'-deoxyinosine nucleosides and 1H-benzotriazol-1-yloxy-tris(dimethylamino)phosphonium hexafluorophosphate (BOP). The reaction appears to proceed via a nucleoside phosphonium salt, and in the absence of any additional nucleophile, the released 1-hydroxybenzotriazole undergoes reaction with the formed phosphonium salt leading to the requisite O6-(benzotriazol-1-yl)inosine or 2'-deoxyinosine derivatives. Isolation and characterization of the phosphonium salt as well as analysis by 31P{1H} NMR appear to be consistent with this reaction pathway. The resulting O6-(benzotriazol-1-yl)inosine derivatives are effective as electrophilic nucleosides, undergoing facile reactions with a variety of nucleophiles such as alcohols, phenols, amines, and a thiol. Unusual and challenging nucleoside derivatives such as an aryl-bridged dimer, a nucleoside-amino acid conjugate, and a nucleoside-nucleoside dimer have also been synthesized from the O6-(benzotriazol-1-yl)-2'-deoxyinosine derivative. Finally, a fully protected DNA building block, the O6-(benzotriazol-1-yl)-2'-deoxyinosine 5'-O-DMT 3'-O-phosphoramidite, has been prepared and a preliminary evaluation of its use for DNA modification has been performed. Results from these studies indicate several important facts: A single, simple methodological approach provides a class of stable, isolable ribo and 2'-deoxyribonucleoside derivatives that possess excellent reactivity for SNAr chemistry with a wide range of nucleophiles. Also, a benzotriazolyl nucleoside phosphoramidite appears to be a suitable reagent for incorporation into DNA for purposes of site-specific DNA modification.     

Synthesis and bioassay of amino-pyrazolone, amino-isoxazolone and amino-pyrimidinone derivatives

Novel amino-pyrazolone, amino-isoxazolone and amino-pyrimidinone derivatives were prepared from ethyl 4-phenylsulfonyl-2-(2'-phenylsulfonylethyl)-2-cyanobutyrate (1), ethyl 4-arylsulfonyl-3-aryl-2-cyanobutyrate (7) and ethyl 4-arylmethylsulfonyl-3-aryl-2-cyanobutyrate (8). The lead molecules have been tested for their antimicrobial activity and antioxidant property.     

Quantum chemical computation by DFT application of NLO molecule 2-aminopyridinium <Emphasis Type="Italic">p</Emphasis>-toluenesulphonate

We investigate the face-to-face collision between multisolitons in spin-1/2 quantum plasma. It is studied in the framework of the model proposed by Marklund et al in Phys. Rev. E 76, 067401 (2007). This study is done with the help of the extended Poincare–Lighthill–Kno (PLK) method. The extended PLK method is also used to obtain two Korteweg–de Vries (KdV) equations and the phase shifts and trajectories during the head-on collision of multisolitons. The collision-induced phase shifts (trajectory changes) are also obtained. The effects of the Zeeman energy, total mass density of the charged plasma particles, speed of the wave and the ratio of the sound speed to Alfvén speed on the phase shifts are studied. It is observed that the phase shifts are significantly affected by all these parameters.     

Modulation of the PGE2-Mediated Pathway in the Eclosion Blocking Effect of Flumethrin and Terpenoid Subfraction Isolated from Artemesia nilagirica in Rhipicephalus annulatus

Prostaglandins are a group of important cell-signaling molecules involved in the regulation of ovarian maturation, oocyte development, egg laying and associated behaviors in invertebrates. However, the presence of prostaglandin E₂ (PGE₂), the key enzymes for PGE₂ biosynthesis and its interference by drugs were not investigated previously in the ovary of ticks. The present study was undertaken to assess the modulation of the PGE₂-mediated pathway in the eclosion blocking effect of flumethrin and terpenoid subfraction isolated from Artemisia nilagirica in Rhipicephalus annulatus ticks. The acaricidal activities and chemical profiling of the terpenoid subfraction were performed. The localization of the cyclooxygenase1 (COX1) and prostaglandin E synthase (PGES) enzymes and the quantification of PGE₂ in the ovaries of the ticks treated with methanol (control), flumethrin and terpenoid subfraction were also undertaken. In addition, the vitellogenin concentration in hemolymph was also assayed. Both flumethrin and the terpenoid subfraction of A. nilagirica elicited a concentration-dependent inhibition of fecundity and blocking of hatching of the eggs. The COX1 could not be detected in the ovaries of treated and control ticks, while there was no significant difference observed in the concentration of vitellogenin (Vg) in them. The presence of PGES in the oocytes of control ticks was confirmed while the immunoreactivities against PGES were absent in the vitellogenic oocytes of ticks treated with flumethrin and terpenoid subfraction. The levels of PGE₂ were below the detection limit in the ovaries of the flumethrin-treated ticks, while it was significantly lower in the ovaries of the terpenoid subfraction-treated ticks. Hence, the prostaglandin E synthase and PGE₂ were identified as very important mediators for the signaling pathway for ovarian maturation and oviposition in ticks. In addition, the key enzyme for prostaglandin biosynthesis, PGES and the receptors for PGE₂ can be exploited as potential drug targets for tick control. The detection of PGES by immunohistochemistry and quantification of PGE₂ by LC-MSMS can be employed as valuable tools for screening newer compounds for their eclosion blocking acaricidal effects.     

Intact cell matrix-assisted laser desorption/ionization mass spectrometry as a tool to screen drugs in vivo for regulation of protein expression

Here we demonstrate for the first time the application of intact cell matrix-assisted laser desorption/ionization mass spectrometry (ICM-MS) to study the regulation of protein expression. This technique can be extended to screen the drugs that inhibit protein synthesis in various diseases. We have used Escherichia coli cells expressing a recombinant glutathione-S-transferase (GST) gene under an arabinose-inducible promoter as a model system. Using ICM-MS analysis, we have detected a 28 kDa peak corresponding to the production of recombinant GST under the arabinose-induced condition. Furthermore, recombinant GST protein was purified by a single-step affinity purification using a glutathione Sepharose 4B affinity column from arabinose-induced E. coli cells. The purified GST protein was found to be a 28 kDa protein by MALDI analysis suggesting the arabinose-induced protein is indeed GST. The regulation of protein expression was studied using glucose as an alternative metabolite. The glucose-mediated regulation of the ara-operon was followed using the ICM-MS technique. All the results obtained from ICM-MS data were validated using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis. The present technique can be extended for in vivo screening of drugs and it holds tremendous potential to discover novel drugs against specific protein expressions in different diseases.