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951.
952.
Amandeep Kaur Sra Marius Andruh Olivier Kahn Stphane Golhen Lahcne Ouahab J. V. Yakhmi 《Angewandte Chemie (International ed. in English)》1999,38(17):2606-2609
Long-range ferromagnetic ordering at 3 K is observed for the title compound, which may be considered as a fully localized mixed-valence species (Mo3+ and Mo4+) as well as a mixed-spin species (low-spin and high-spin Mn2+ ions). Its two-dimensional structure consists of heart-shaped 48-membered rings, and each ring contains 16 metal centers (see picture). 相似文献
953.
Using modified Baker-Venkataraman reaction a novel class of 3-acyl flavones and chromones have been synthesised. Reaction mechanism for their formation have been elucidated. The properties of 3-acyl flavonoids indicate them to be precursors for the synthesis of flavones. 相似文献
954.
Thermal behaviour of a number of organomercury(II) complexes of the type, p-XC6H4HgCl(L1) (I), p-XC6H4HgCl3(L2) (II), p-XC6H4HgL3 (III) and p-XC6H4HgL4 (IV) [L
1=isoniazid, L
2=theobromine, L
3=phenyldithiocarbamate, L
4=p-nitrophenyldithiocarbamate; X=Me, MeO, NO2] has been investigated. From TG curves, the order and activation energy of the thermal decomposition reaction have been elucidated. The variation of the activation energy has been correlated with the nature of the substituent on the phenyl ring. The heat of reaction has been elucidated from DSC or DTA studies. The fragmentation pattern has been analysed on the basis of mass spectra.This revised version was published online in November 2005 with corrections to the Cover Date.A part of this work was carried out at Intitute of Microbial Technology, Chandigarh, under the Visiting Associateship Scheme (1992–95) of the Council of Scientific and Industrial Research, New Delhi. 相似文献
955.
The proton affinities of all the potential sites of oxazolidinone (OXA) and formyl substituted OXA have been evaluated using
ab initio and DFT methods. N4- and C5-formyl oxazolidinone isomers and their protonated structures have been analyzed for
relative stabilities. The proton affinity (PA) of carbonyl oxygen of oxazolidinone is observed to be highest in un-substituted
and formyl substituted OXA molecules. The PA values decrease for the potential sites in the range 0.5–15.51 kcal/mol as a
result of the presence of the formyl substituent. Atomic charges and electron delocalization of neutral and protonated species
have been analyzed with the application of NBO. The various factors such as variation in geometrical parameters, atomic charge
redistribution, alterations in conjugative interactions, effect of formyl substituent, the presence of intramolecular hydrogen
bonding and electronic effects have been explored to rationalize the relative stabilities and proton affinities of OXA and
its N,C5 formyl derivatives. 相似文献
956.
Summary The reaction of 3,4-methylenedioxycinnamic acid (1) with thionyl chloride resulted in the formation of 7-chlorothieno[2,3-f]-1,3-benzodioxole-6-carbonyl chloride (2) and cinnamoyl chloride (3). Subsequent reaction of the former withp-substituted anilines led to the formation of 7-chloro-N-(p-substituted phenyl)-thieno[2,3-f]-1,3-benzodioxole-6-carboxamides (4a–c) which on photocyclization afforded 2-substituted [1,3]dioxolo[5,6][1]benzothieno[2,3-c]quinolin-6(5H)-ones (5a–c) in fairly good yields and high purity. The structures have been confirmed by IR,1H NMR, and analytical methods.Accepted for presentation at the Hong Kong International Symposium on Heterocyclic Chemistry (August 13–16, 1995) 相似文献
957.
Guneet Kaur Ashok K. Srivastava Subhash Chand 《Applied biochemistry and biotechnology》2012,167(5):1061-1068
Repeated batch cultivation (empty-and-fill protocol) using obligate anaerobe Clostridium diolis was attempted in the present study to improve the production of 1,3-propanediol (1,3-PD). In repeated batch operation, 20?% (v/v) culture broth was removed from the bioreactor and supplemented with an equal volume of fresh nutrient medium when the residual glycerol concentration in the bioreactor decreased below 15?g/L. Four cycles of culture broth withdrawal and subsequent replacement resulted in achieving a 1,3-PD concentration of 67.8?g/L with a productivity of 1.04?g/L/h at the end of 65?h. This represented a 1,3-PD concentration and productivity enhancement by 2.6-fold and 1.5-fold, respectively, as compared to batch 1,3-PD fermentation. This is the first report on the use of repeated batch mode of bioreactor operation for enhanced 1,3-PD production. 相似文献
958.
Jasvinder Kaur Hayre Guogang Xu Luisa Borgianni Garry L Taylor Peter W Andrew Jean-Denis Docquier Marco R Oggioni 《BMC biochemistry》2012,13(1):1-7
Backgrounds
Streptococcus pneumoniae expresses three distinct sialidases, NanA, NanB, and NanC, that are believed to be key virulence factors and thus, potential important drug targets. We previously reported that the three enzymes release different products from sialosides, but could share a common catalytic mechanism before the final step of product formation. However, the kinetic investigations of the three sialidases have not been systematically done thus far, due to the lack of an easy and steady measurement of sialidase reaction rate.Results
In this work, we present further kinetic characterization of pneumococcal sialidases by using a direct spectrophotometric method with the chromogenic substrate p-nitrophenyl-N-acetylneuraminic acid (p-NP-Neu5Ac). Using our assay, the measured kinetic parameters of the three purified pneumococcal sialidase, NanA, NanB and NanC, were obtained and were in perfect agreement with the previously published data. The major advantage of this alternative method resides in the direct measurement of the released product, allowing to readily determine of initial reaction rates and record complete hydrolysis time courses.Conclusion
We developed an accurate, fast and sensitive spectrophotometric method to investigate the kinetics of sialidase-catalyzed reactions. This fast, sensitive, inexpensive and accurate method could benefit the study of the kinetics and inhibition of sialidases in general. 相似文献959.
Mandeep?S.?BakshiEmail author Rajinderpal?Kaur Ishpinder?Kaur Rakesh?Kumar Mahajan Pankaj?Sehgal Hidekazu?Doe 《Colloid and polymer science》2003,281(8):716-726
Single and mixed micelle formation by sodium dodecyl sulfate (SDS) and sodium dodecylbenzene sulfonate (SDBS) and their mixtures in pure water and in the presence of water-soluble polymers such as Synperonic 85 (triblock polymer, TBP), hydroxypropylcellulose (HPC), and carboxymethylcellulose sodium salt (CMC) were studied with the help of conductivity, pyrene fluorescence, cyclic voltammetry, and viscosity measurements. Conductivity measurements showed a single aggregation process for pure surfactants and their mixtures both in pure water as well as in the presence of water-soluble polymers. Triple breaks corresponding to two aggregation processes for SDS, SDBS, and their mixture in the presence of TBP were observed from fluorescence measurements. The first one demonstrated the critical aggregation process due to the adsorption of surfactant monomers on TBP macromolecule. The second one was attributed to the participation of surfactant–polymer aggregates formed at the first one, in the micelle formation process. The aggregation number ( N agg) of single and mixed micelles and diffusion coefficient ( D) of electroactive probe were computed from the fluorescence and cyclic voltammetry measurements, respectively. Both parameters, along with the viscosity results, indicated stronger SDS–polymer interactions in comparison to SDBS–polymer interactions. Mixed surfactant–polymer interactions showed compensating effects of both pure surfactants. The nature of mixed micelles was found to be ideal in all cases, as evaluated by applying the regular solution and Motomura's approximations. 相似文献
960.
A new stability-indicating reversed-phase LC method has been developed and validated for the assay and identification of betamethasone dipropionate and its related compounds in a dermatological pharmaceutical drug product, namely Diprolene Ointment. Separation of all the peaks of interest was achieved on a Symmetry Shield RP18 (100 mm × 4.6 mm, 3.5 µm) column using a gradient elution at a flow rate of 1.5 mL min?1 with mobile phase A (10 mM monobasic sodium phosphate at pH 2.5) and mobile phase B (acetonitrile) and UV detection at 250 nm. The limit of detection (LOD) and limit of quantitation (LOQ) of this method was 0.00004 and 0.0001 mg mL?1, respectively. The method was successfully validated in accordance with ICH guidelines and was accurate, linear, precise, reproducible, specific, and robust. A simple, reproducible and accurate single step sample extraction procedure using tetrahydrofuran, water, and methanol (40:30:30, v/v/v) was developed to extract betamethasone dipropionate and its related compounds from the ointment. The sample extraction procedure and the LC conditions presented in this report can be used for routine analysis of Diprolene Ointment in quality control laboratories. This method may also be applied to other dermatological pharmaceutical drug products “as-is” or with minor modification. 相似文献