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41.
A simple and efficient total synthesis of patulolide A from readily available 7-octen-1-ol is reported by asymmetric synthetic approach. The key reactions involved are asymmetric dihydroxylation using AD-mix-β and Grubbs’ ring-closing metathesis reaction for the synthesis macrocyclic ring system. 相似文献
42.
In this study, a liquid-phase separation platform consisting of tandem lectin affinity chromatography was introduced for the selective capturing of sub-glycoproteomics that are affected in cancers, e.g. breast cancer. The platform is comprised of three monolithic columns with surface immobilised lectins including concanavalin A (Con A), wheat germ agglutinin (WGA) and Ricinus communis agglutinin-I (RCA-I). While WGA and Con A have specificities directed towards the core portion of N-glycans on the glycoprotein surface, RCA-I specifically interacts with the non-reducing terminal moieties of the outer chain structures of N-glycans. The effects of the order in which the three lectin columns were arranged in the tandem columns format were evaluated. The most suitable order proved to be WGA → Con A → RCA-I (denoted as WCR) as far as the number of captured proteins was concerned. The WCR tandem columns allowed the capture of 113 and 112 proteins from disease-free and breast cancer sera, respectively, corresponding to 75 and 65 non-redundant proteins, respectively. Using mass spectral count ratios and Q-Q plots yielded a panel of 23 non-redundant differentially expressed proteins (i.e. a panel of 23 candidate markers), which should in principle be more representative of a pathophysiological state than a single marker candidate. 相似文献
43.
Poly (vinyl alcohol – aniline) PVAA composite was tested for its performance in protecting mild steel MS against corrosion in 1 M HCl. The inhibitive parameters were evaluated by means of weight loss, electrochemical polarization and impedance methods. Results indicated that the addition of PVAA to the acid reduces the corrosion of the metal. Inhibition efficiency increases with increase in inhibitor concentration. The results further revealed that PVAA at a concentration of 2000 ppm furnishes a maximum of 92% inhibition efficiency. Thermodynamic parameters such as free energy of adsorption, heat of adsorption, etc., had been evaluated from temperature studies. The adsorption of PVAA followed Langmuir and Temkin adsorption isotherms. Polarization curves revealed that PVAA is a mixed inhibitor. 相似文献
44.
Subbiah Meenakshisundaram M. Selvaraju N. M. Made Gowda Kanchugarakoppal S. Rangappa 《国际化学动力学杂志》2005,37(11):649-657
Mechanistic studies on the oxidation of 18 meta‐, para‐, and ortho‐substituted anilines (Ans) by HOOSO−3 in aqueous acetonitrile medium have been performed. The reaction can be characterized by the experimental rate equation, The addition of p‐toluenesulfonic acid (TsOH) retards the reaction. The increase in the reactivity of anilines as the medium is made more aqueous is interpreted. The reaction is enhanced by electron‐donating groups on the amine in the series consistent with the rate‐limiting nucleophilic attack of the amine on the persulfate oxygen. The proposed mechanism involves the conversion of phenylhydroxylamine to nitrosobenzene in a fast step. The ESR study reveals the absence of free radicals in the reaction. Various attempts have been made to analyze the experimental rate constants in terms of LFER plots. Improved correlations are obtained with σ− values and the σ− form of the Yukawa–Tsuno equation. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 649–657, 2005 相似文献
45.
The photophysics and photochemistry of 1,8-acridinedione dyes, which are analogues of reduced nicotinamide adenine dinucleotide (NADH), are studied in anionic and cationic micelles. Acridinedione dyes (ADDs) are solubilized in micelles at the micelle-water interface and are in equilibrium between the aqueous and micellar phase. The binding of the ADDs with micelles is attributed to hydrophobic interactions and the binding constants are determined with steady-state and time-resolved techniques. Nanosecond laser flash photolysis studies are carried out in aqueous, anionic, and cationic micellar solutions. The ADD undergoes photoionization in the excited state to give a solvated electron. The solvated electron reacts with the ADD to give an anion radical. In anionic micelles, the yield of the solvated electron increases because of the efficient separation of the cation radical and the electron. Cation radicals derived from the photooxidation of ADDs are involved in keto-enol tautomerization. Under acidic conditions, an enol radical cation of the acridinedione dye is formed from the keto form of the cation radical by intramolecular hydrogen atom transfer. In cationic micelles, due to electrostatic attraction, the electron cannot escape from the micelle and recombination of the cation radical and the electron results in the formation of a triplet state. For the first time, a solvated electron is observed in the laser flash photolysis of ADDs in anionic micelles. The photoionization of ADDs depends on the excitation wavelength and is biphotonic at 355 nm and monophotonic at 248 nm. From the results with this NADH model compound, the sequential electron-proton-electron transfer oxidation of NADH is confirmed and the nature of the intermediates involved in the oxidation is unraveled; these intermediates are found to depend on the pH value of the medium. 相似文献
46.
The electrochemical, selective determination of catechol (CT) in the presence of hydroquinone (HQ) is not readily achieved, because the formal potentials of two phenolic compounds are very close. Here, we have developed a simple electrochemical method for the selective determination of CT by using bare indium tin oxide electrodes and employing CT redox cycling by hydrazine. The cyclic voltammetry of CT and HQ was investigated in Tris buffer (pH 9.0), phosphate buffered saline buffer (pH 7.4), and acetate buffer (pH 4.5). Especially in Tris buffer, the anodic peak potential of CT is much lower than that of HQ, resulting in a large difference between two peak potentials (ca. 0.4 V). The difference allows the selective determination of CT in the presence of excess HQ. The anodic current of CT is amplified using CT redox cycling by hydrazine, which also helps to stabilize CT and HQ in Tris buffer for several hours. The detection limits of CT in Tris buffer containing 0.1 mM HQ are 1 μM and 10 μM in the presence and absence of hydrazine, respectively. 相似文献
47.
M. Subhashini M. S. Subramanian V. R. S. Rao 《Journal of Radioanalytical and Nuclear Chemistry》1987,108(1):25-30
Aqueous chloramine-B /C6H5SO2NCl Na/ solution is known to contain species like RNCl–, RNHCl, RNCl2, RN+H2Cl, HOCl and H2+OCl where R=C6H5SO2. The exchange studies between36Cl and CAB carried out in various media by ion-exchange method indicated that there is no exchange in solution at pH7. As the pH is decreased below 7, the extent of exchange increases reaching a maximum at pH 3. 3. The exchange decreases as the acidity is increased between pH 3.3 and 1N and again the exchange increases beyong 1N. The observed increase in exchange in strong acid medium is due to the evolution of chlorine. 相似文献
48.
Kirubavathi K Selvaraju K Kumararaman S 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,71(1):1-4
A new semiorganic nonlinear optical bis (thiourea) cadmium zinc chloride (BTCZC) crystal has been synthesized. BTCZC single crystals were grown from aqueous solution by slow evaporation technique. The solubility of BTCZC has been determined for various temperatures. Single crystal X-ray diffraction (XRD) study has been carried out to identify the lattice parameters. Fourier transform infrared (FTIR) studies confirm the various functional groups present in the grown crystal. The transmission and absorption spectra of this crystal show that the lower cut off wavelength lies at 260nm. The thermal analyses confirmed that the crystal is stable upto 201 degrees C. The nonlinear optical (NLO) property of the grown crystal has been confirmed by Kurtz-powder second harmonic generation (SHG) test. 相似文献
49.
K. Selvaraju K. Kirubavathi N. Vijayan S. Kumararaman 《Journal of Crystal Growth》2008,310(11):2859-2862
The nucleation parameters such as, energy per unit volume, radius of critical nucleus, critical free energy barrier, number of molecules in the critical nucleus and nucleation rate have been evaluated for bis glycine sodium nitrate single crystals. The interfacial energy of the solution at various temperatures has been estimated from existing solubility data. The metastable zone width and induction period measurements have been carried out experimentally. 相似文献
50.
Subhashini Naikal James Prameela Lavanya Jilla Sowmya Vanguru 《Journal of heterocyclic chemistry》2020,57(1):308-316
A new series of benzosuberone-piperazine hybrids 6a to j were designed and synthesized efficiently in good yields and their structures were confirmed by 1H NMR, 13C NMR, ESI-MS and HRMS. The newly synthesized compounds were evaluated for their in vitro antimicrobial activity against Gram positive, Gram negative bacterial strains and a fungal strain. Among the synthesized compounds, compounds 6c , 6d , 6e , 6f , 6g and 6h exhibited potent antibacterial activity with MIC value of 1.9 μg/mL against Gram positive and Gram negative organisms. 相似文献