Effect of ZnO/CdO on the structure and electrical conductivity in Li2O·MO·Bi2O3·B2O3 glasses (M=Zn, Cd)

Studies of structural and electrical properties have been carried out on a number of glasses with wide ranging compositions in the glass systems Li₂O·MO·Bi₂O₃·B₂O₃ (where M=Zn or Cd), in order to understand the effect of transition metal (TM) ions on the structure of these glasses. The density and molar volume measurements have also been made to understand the structural changes occurring in these glasses. The dc conductivity measured in the temperature range 423-623 K obeys Arrhenius law. It increases with increase in Li₂O/MO ratio. The results of infrared spectra indicate that TM ions (Zn²⁺ or Cd²⁺) behave as network former in the present system. Boron exists in both tri- and tetra-hedral units in these glasses and no boroxol ring formation takes place in the glass structure. Values of theoretical optical basicity have also been reported.     

Representation of orthofermion spin operators

The algebraic expressions for the total spin operators expressed in terms of orthofermion creation and annihilation operators are combined into a single equation. The terms in this expressions are rearranged to provide representations of local spin operators. This task is essential for modelling a system of orthofermions in the presence of a magnetic field. By factorizing the orthofermion annihilation (creation) operators into charge and spin dependent parts, it is shown that the latter part suffices to represent spin number, raising and lowering operators. Finally a connection is provided between the spin systems and Greenberg’s infinite statistics.     

Novel Etodolac-Based 1,2,4-Triazole Derivatives as Antimicrobial Agents: Synthesis,Biological Evaluation,and Molecular Docking Study

Russian Journal of Organic Chemistry - A series of novel 1,2,4-triazole nonsteroidal anti-inflammatory drugs (NSAIDs) derived from etodolac were designed and synthesized. The synthesized compounds...     

Synergic Synthesis and Characterization of tert-Butyl 4-[(E)-But-1-en-3-yn-1-yl]-3-{[tert-butyl(dimethyl)silyl]oxy}-1H-indole-1-carboxylate

Russian Journal of Organic Chemistry - tert-Butyl 4-[(E)-but-1-en-3-yn-1-yl]-3-{[tert-butyl(dimethyl)silyl]oxy}-1H-indole-1-carboxylate has been synthesized with a good yield and selectivity...     

Sensitive method for the determination of paricalcitol by liquid chromatography and mass spectrometry and its application to a clinical pharmacokinetic study

A highly sensitive, specific and rapid LC‐ESI‐MS/MS method has been developed and validated for the quantification of paricalcitol (PAR) in human plasma (500 μL) using paricalcitol‐d₆ (PAR‐d₆) as an internal standard (IS) as per regulatory guidelines. A liquid–liquid extraction method was used to extract the analyte and IS from human plasma. Chromatography was achieved on Zorbax SB C₁₈ column using an isocratic mobile phase in a gradient flow. The total chromatographic run time was 6.0 min and the elution of PAR and PAR‐d₆ occurred at ~2.6 min. A linear response function was established for the range of concentrations 10–500 pg/mL in human plasma. The intra‐ and inter‐day accuracy and precision values for PAR met the acceptance criteria. The validated assay was applied to quantitate PAR concentrations in human plasma following oral administration of 4 µg capsules to humans. Copyright © 2014 John Wiley & Sons, Ltd.     

Total synthesis of modified pentapeptide,caldoramide

Total synthesis of modified pentapeptide, caldoramide, a cytotoxic linear pentapeptide from the marine cyanobacterium Caldora penicillate is described. Notable features of the route include the efficient preparation of three key fragments and final assembly to the natural product via sequential amide couplings. The spectral data of the synthetic compound was found to be in comparison with that of the isolated natural product.     

Greener approach toward the generation of dimedone derivatives

The use of dimedone in green chemistry has been described for the synthesis of selective heterocyclic motifs which are both pharmacologically and industrially important. The objective of this review is to summarize some of the selected recent advances of dimedone in the synthesis of organic compounds utilizing green chemistry procedures.     

Synthesis and conformational studies of peptides from new C-linked carbo-beta-amino acids (beta-Caas) with anomeric methylamino- and difluorophenyl moieties

New C-linked carbo-beta-amino acids (beta-Caas), Cbz-(S)-beta-Caa-(NHBoc)-OMe (1) and Cbz-(R)-beta-Caa-(NHBoc)-OMe (2), with an additional amine group (methylamino group of NHBoc) at the C-1 position of the lyxofuranoside side chain and Boc-(S)-beta-Caa-(diFP)-OMe (3) and Boc-(R)-beta-Caa-(diFP)-OMe (4), with a C-difluorophenyl (diFP) moiety at the anomeric position of the lyxofuranoside side chain were prepared from D-mannose. Beta-peptides [tetra- and hexapeptides] were synthesized from these beta-Caas, 'epimeric' [at the amine stereocentre (C(beta))], using the concept of 'alternating chirality' to carry out their conformational studies [NMR (CDCl(3)), CD and MD]. In the monomer design, it was envisaged that the presence of an additional amine group in 1 or 2 would help in solubilizing the peptides in water, while, the C-difluorophenyl (diFP) moiety of 3 and 4 is expected to enhance the biological activity. The peptides having 1 and 2, though could not retain their 12-10-mixed helices in water, have shown moderate activity against gram positive and gram negative bacterial strains. The peptides prepared from 3 and 4, much against our expectations, did not display any biological activity.     

Isothermal titration calorimetric and spectroscopic studies on (alcohol + salt) induced partially folded state of α-lactalbumin and its binding with 8-anilino-1-naphthalenesulfonic acid

Interaction of 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) and isopropanol in the presence of equimolar quantities of guanidine thiocyanate (GndSCN) with bovine α-lactalbumin (α-LA) has been investigated by using a combination of isothermal titration calorimetry, circular dichroism, fluorescence, and ultra-violet spectroscopies at in 20 · 10^?3 mol · dm^?3 phosphate buffer pH 7.0. All the thermal unfolding transitions, in the presence of both the (alcohol + salt) mixtures were found to be reversible as judged by the same values of absorbance observed at different temperatures during cooling after the completion of thermal unfolding. In the presence of the 0.25 mol · dm^?3 (HFIP + GndSCN) equimolar mixture and 0.85 mol · dm^?3 (isopropanol + GndSCN) equimolar mixture, α-lactalbumin was observed to be in the partially folded state with significant loss of native tertiary structure. Intrinsic fluorescence results, acrylamide and potassium iodide quenching, 8-anilino-1-naphthalenesulfonic acid (ANS) binding, and energy transfer results also corroborate the presence of partially folded states of α-lactalbumin. Apart from the generation of the partially folded states, it was also observed that destabilizing action of GndSCN is reduced in the presence of isopropanol compared to that in HFIP. Isothermal titration calorimetry has been used to characterize the energetics of ANS binding to the partially folded states of the protein. ITC results indicate that ANS binds to these partially folded states at pH 7.0 due to the presence of two sequentially binding sites on the protein under the solvent conditions employed. For example, ANS binds to the 0.25 mol · dm^?3 (HFIP + GndSCN) induced partially folded state with affinity constants K₁ = (858 ± 220), K₂ = (1.12 ± 0.25) · 10³; enthalpies of binding ΔH₁ = (4.4 ± 1.0) kJ · mol^?1, ΔH₂ = (2.1 ± 0.2) kJ · mol^?1; and entropies of binding ΔS₁ = 70 J · K^?1 · mol^?1 and ΔS₂ = 65 J · K^?1 · mol^?1, respectively at these two sequential binding sites. In light of the fluorescence results, possible binding sites where ANS can bind to the protein have also been suggested.     

Insights into the energetics and mechanism underlying the interaction of tetraethylammonium bromide with proteins

Calorimetry has been employed to investigate the quantitative energetic aspects and mechanism underlying protein–tetraethylammonium bromide (TEAB) interactions. Differential scanning calorimetry and UV–Visible spectroscopy have been used to study the thermal unfolding of three proteins of different structure and function (bovine serum albumin, α-lactalbumin, and bovine pancreatic ribonuclease A). The mode of interaction has been studied by using isothermal titration calorimetry, which demonstrates the absence of appreciable specific binding of TEAB to the protein. This suggests the involvement of solvent mediated effects and, possibly weak non-specific binding. The thermal unfolding transitions were found to be calorimetrically reversible for α-lactalbumin and bovine pancreatic ribonuclease A and partially reversible in the case of bovine serum albumin. The results indicate protein destabilization promoted by the TEAB interaction. The preferential interaction parameters of TEAB with α-lactalbumin and ribonuclease A confirm that an increased interaction of the hydrophobic groups of the TEAB with that of the protein upon denaturation is responsible for the reduced thermal stability of the protein. The decrease in the thermal stability of proteins in the presence of TEAB is well supported by a red shift in the intrinsic fluorescence of these proteins leading to conformational change thereby shifting the native ? denatured equilibrium towards right. The forces responsible for the thermal denaturation of the proteins of different structure and function in the presence of TEAB are discussed.