Enhanced grain growth in YBa2Cu3O7−δ doped with Ag,Cu, and CuO

Powders of YBa₂Cu₃O_7– were mixed with Ag, Cu, and CuO powders, pressed and sintered in air and oxygen. Grain-growth enhancement has been observed in the doped samples on sintering in oxygen at 980°C and its attributable to a partial melting and decomposition followed by crystallization during cooling. While the mechanisms of the partial melt may differ with dopant, grain growth enhancement appears to be a common feature of partial melt followed by slow cooling. The possibility of using suitable dopants in aiding an aligned grain structure is pointed out.     

Iron(III) complexes of 2-acetylpyridine-4-phenyl-3-thiosemicarbazones: Magnetic,E.s.r. and spectral studies

Summary Iron(III) complexes of 2-acetylpyridine-4-phenyl-3-thiosemicarbazone (LH) with the general formulae FeLX₂ (X = Cl, Br, NO₃ or SCN) and FeLSO₄ have been prepared and characterised by elemental analysis and by magnetic measurements in the polycrystalline state in the 77–298 K range and by electronic, i.r. and e.s.r. spectra. The FeLX₂ species (X = Cl, NCS or NO₃) are square pyramidal of intermediate spin-state (S=3/2) with an⁴ A ₂ ground state. The magnetic behaviour of FeLSO₄ is commensurate with high order effects coupled with antiferromagnetic exchange interactions. FeLBr₂ is a spin-free dimer involving bromine bridging between two FeLBr₂ square pyramids. However, the low-spin species [FeL(DMF)₃]²⁺ exists in dimethylformamide solution.     

Polarographic reduction of some guanylpyrazoline nitrates and the effect of double layer structure on E1/2 values

Polarographic reduction of 4-arylhydrazono-1-guanylnitrate-3-methyl-2-pyrazoline-5-ones takes place in a single 4-electron transfer, giving a diffusion controlled irreversible wave in B.R. buffers of pH range 2.0–10.0. The reduction in these compounds takes place at the ?NH?N=C-bond. Effect of various cations, anions and solvent percentage on the reduction has been discussed. The effect of substituents and its correlation with the Hammett substituent constant (δ) have also been studied.     

High energy muon-nucleon inelastic scattering at lowq 2

The inelastic interactions of 150 GeV positive muons produced at Fermi Laboratory have been studied in nuclear emulsion. Secondary particles produced in these interactions have been identified, the energy spectra and angular distributions for pions and protons are given. The inclusive pionproduction reaction is studied and the relative shape ofp _t ² distribution is discussed. The average charged multiplicity relations are determined as a function of different parameters and are compared with the multiplicities produced in pure hadronic interactions. The integral cross sections have been measured and are compared with the first and second powers of 1/(1+q ²/m _p ² ) forσ _exp(q ²,v), the quantity commonly called the “virtualphoton-nucleon total cross section”. The values of the structure function νW ₂ are calculated for 0.02≤q ²≤0.5. The present data are compared with other muon data at the same energy.     

Lattice instability in Hf1-x Ta x V2 compounds

The temperature dependence of the electric quadrupole interaction frequency _l ^o , experienced by the¹⁸¹Ta probe occupying Hf site in the compounds Hf_1-xTa_xV₂ has been measured for x=0.06, 0.10 and 0.20 in the temperature region between 8.5 K to 296 K. The measurements show lattice transformation in all the three compounds below 120 K.     

The biosynthesis of the alkaloids of croton sparsiflorus morong

Incorporation of tyrosine, dopa, dopamine, 4-hydroxyphenylpyruvic acid, (±)-, norcoclaurine-1-carboxylic acid, -norcoclaurine, -coclaurine, and -N-methylcoclaurine into N-methylcrotsparine, N-methylcrotsparinine and N-methylsparsiflorine in Croton sparsiflorus Morong has been studied. The evidence supports the direct oxidative coupling of (+)-, and (-)-N-methylcoclaurines to give N-methylcrotsparine and N-methylcrotsparinine respectively. Tracer experiment show that N-methylcrotsparine undergoes dienone-phenol rearrangement to give N-methylsparsiflorine. A double labelling experiment with (±)-N[¹⁴C]methyl[1-³H]coclaurine demonstrated that the H atom at the asymmetric centre in the 1-benzylisoquinoline precursor is retained in the bioconversion. The intermediacy of norcoclaurine-1-carboxylic acid and specific incorporation of dehydro-N-methylcoclaurinium salt into the bases have been demonstrated.     

Heterocyclic inflammation inhibitors

Non steroidal anti-inflammatory drugs are the most widely used medicines for relief of pain. These drugs have some side effects, particularly toxicity in the gastrointestinal tract and kidneys. Various approaches have been used for obtaining safer anti-inflammatory drugs. In this review we have summarized the recent developments in the following areas; (i) mode of action of NSAIDs (ii) Role of COX-1 & COX-2 in inflammation, (iii) Different approaches used to improve gastric tolerance i.e. chemical manipulation, formulation & co-administration, development of non specific (COX-1 & COX-2 inhibitors) and specific (COX-2 inhibitors) inflammation inhibitors, and development of inflammation inhibitors having a mode of action other than COX-1 & COX-2 inhibition. We have also focused on the safety of COX-2 inhibitors and the synthesis of heterocyclic compounds and their role as inflammation inhibitors.