Form I of desloratadine,a tricyclic anti­histamine

The title compound [systematic name: 8‐chloro‐11‐(piperidin‐4‐yl­idene)‐6,11‐dihydro‐5H‐benzo[4,5]cyclo­hepta­[2,1‐b]pyridine], C₁₉H₁₉ClN₂, was crystallized from ethyl acetate. The inter­esting feature of the reported structure is that it does not contain any strong hydrogen bonds, although the mol­ecule contains a secondary NH group, which is a good hydrogen‐bond donor.     

Study of the peak effect phenomenon in single crystals of 2H-NbSe2

The weakly pinned single crystals of the hexagonal 2H-NbSe₂ compound have emerged as prototypes for determining and characterizing the phase boundaries of the possible order-disorder transformations in the vortex matter. We present here a status report based on the ac and dc magnetization measurements of the peak effect phenomenon in three crystals of 2H-NbSe₂, in which the critical current densities vary over two orders of magnitude. We sketch the generic vortex phase diagram of a weakly pinned superconductor, which also utilizes theoretical proposals. We also establish the connection between the metastability effects and pinning.     

High temperature annealing effect on structural and magnetic properties of Ti/Ni multilayers

High temperature annealing effect on structural and magnetic properties of Ti/Ni multilayer (ML) up to 600 °C have been studied and reported in this paper. Ti/Ni multilayer samples having constant layer thicknesses of 50 Å each are deposited on float glass and Si(1 1 1) substrates using electron-beam evaporation technique under ultra-high vacuum (UHV) conditions at room temperatures. The micro-structural parameters and their evolution with temperature for as-deposited as well as annealed multilayer samples up to 600 °C in a step of 100 °C for 1 h are determined by using X-ray diffraction (XRD) and grazing incidence X-ray reflectivity techniques. The X-ray diffraction pattern recorded at 300 °C annealed multilayer sample shows interesting structural transformation (from crystalline to amorphous) because of the solid-state reaction (SSR) and subsequent re-crystallization at higher temperatures of annealing, particularly at ≥400 °C due to the formation of TiNi₃ and Ti₂Ni alloy phases. Sample quality and surface morphology are examined by using atomic force microscopy (AFM) technique for both as-deposited as well as annealed multilayer samples. In addition to this, a temperature dependent dc resistivity measurement is also used to study the structural transformation and subsequent alloy phase formation due to annealing treatment. The corresponding magnetization behavior of multilayer samples after each stage of annealing has been investigated by using Magneto-Optical Kerr Effect (MOKE) technique and results are interpreted in terms of observed micro-structural changes.     

Collective mechanism for nuclear stopping and transverse flow in heavy-ion collisions

The role of filamentation instability of quark-gluon plasma, in explaining collective phenomena in relativistic heavy-ion collisions, has been analyzed. Using equations of SU(2) two fluid color hydrodynamics it is shown that this instability can significantly enhance nuclear stopping and might contribute to collective sideward flows.     

Kinetic and structural characterization of human manganese superoxide dismutase containing 3-fluorotyrosines

Incorporation of 3-fluorotyrosine and site-specific mutagenesis have been used with stopped-flow spectrophotometry and pulse radiolysis to investigate the catalytic properties of human manganese superoxide dismutase (MnSOD). All of the nine tyrosine residues in each of the four subunits of the homotetramer of human MnSOD were replaced with 3-fluorotyrosine. Previous studies showed that the crystal structures of the unfluorinated and fluorinated human MnSOD are nearly superimposable with the root-mean-square deviation for 198 -carbon atoms at 0.3 Å. However, the catalytic activity k_cat/K_m of the fluorinated MnSOD at 30 μM⁻¹ s⁻¹ was less than unfluorinated wild type at 800 μM⁻¹ s⁻¹. Comparison of the values of k_cat/K_m for fluorinated and unfluorinated wild-type andY34F MnSOD showed that this decrease for the fluorinated enzyme was in significant part due to 3-fluorotyrosine residues distant (>7 Å) from the active-site metal, not to 3-fluorotyrosine at position 34 close (5 Å) to the metal. Although many rate constants for the catalysis are decreased by this fluorination, the rate of dissociation of the product-inhibited complex appears unchanged by the presence of fluorinated tyrosines. These results suggest that Tyr34 is not a proton donor in the release of the product-inhibited complex, which involves protonation of a peroxo complex of the metal with release of hydrogen peroxide.     

Thermal studies of some aryloxides of titanium(IV)

Thermal behaviour of aryloxides of titanium(IV) of composition TiCl_n(OAr)_4?n (wheren=0→3 and OAr=OC₆Bu^t-4, OC₆H₄OMe-4 and OC₆H₂-Bu ₂ ^t -2,6?Me-4) has been studied by DTA and TG analysis. Multiple decomposition steps have been indicated by thermal weight losses which are both exothermic and endothermic as shown by DTA curves. Based upon the total % loss in weight; during entire decomposition titanium dioxide has been found to be the final residue in each case.     

Synthesis of 5-ethynylorotic acid

Condensation of 2,4-dimethoxy-5-iodo-6-carbomethoxypyrimidine ( 10 ) with copper (I) 3-tetrahydropyranyloxyprop-1-ynide ( 4 ) afforded 2,4-dimethoxy-5-(3′-tetrahydropyranyloxyprop-1′-yn)-6-carbomethoxypyrimidine ( 11 ), which was hydrolyzed to produce 2,4-dimethoxy-5-(3′-hydroxyprop-1′-yn)-6-carbomethoxypyrimidine ( 12 ). Oxidation of 12 with dimethyl sulfoxide-oxalyl chloride reagent gave the acetylenic aldehyde ( 13 ), which on treatment with sodium methoxide in dry tetrahydrofuran yielded 2,4-dimethoxy-5-ethynyl-6-carbomethoxypyrimidine ( 14 ). The trimethylsilyl derivative ( 15 ) was deprotected by sequential treatment with iodotrimethylsilane and aqueous sodium hydroxide, leading to the formation of 5-ethynylorotic acid ( 1 ).