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101.
A parametric study to increase the enantioselectivity of Candida rugosa lipase (CRL) toward S-Naproxen production by the hydrolysis of racemic Naproxen methyl ester in an aqueous-organic biphasic
batch system was carried out. Effects of organic solvent type, aqueous phase/organic solvent volume ratio, agitation rate,
concentrations of the substrate and the enzyme, pH of the aqueous phase, and temperature on the en antiomeric excess for the
product (eep), on the enantiomeric ratio (E) and on the conversion (x) were evaluated. Employing isooctane as the solvent resulted in
higher eep, E, and x than those obtained in hexane, cyclohexane, and toluene. The higher the volume ratio of aqueous phase/organic solvent
employed, the higher the conversion and enantioselectivity achieved. The increase in agitation rate increased the hydrolysis
rate. Higher concentration of racemic Naproxen methyl ester than 10 mg/mL decreased both the conversion and enantioselectivity.
The increase in crude CRL concentration resulted in enhancement of x, but the decrease of feep and E. Acidic pH led to higher conversion and enantioselectivity than the medium and alkaline pH values. A further increase
in temperature to over 45°C decreased the conversion and enantioselectivity. The highest enantiomeric ratio achieved in the
S-Naproxen production was E=171.1, with x=49.8% and eep=95.7%. 相似文献
102.
The extraction of copper(II), nickel(II) and cobalt(II) from the aqueous phase with N,N'-bis(salicylaldehydene)-1,4-bis-(m-aminophenoxy)butane (MAS), which was synthesized from 1,4-bis(m-aminophenoxy)butane and salicylaldehyde, was studied. Microanalytical data, elemental analysis, UV-visible 1H and 13C n.m.r. spectra and IR-spectra were used to confirm the structures. The extractability and selectivity of divalent cations were evaluated as a function of relationship between distribution ratio of the metal and pH or ligand concentration. Cu+2 showed the highest extractability and selectivity at pH 6.0, whereas Ni+2 and Co+2 showed at pH 9.2. The stoichiometries of the compounds formed were estimated to be CuL, CoL, NiL, where L is N,N'-bis(salicylaldehydene)-1,4-bis-(m-aminophenoxy)butane. It was concluded that MAS can effectively be used in solvent extraction of copper(II), nickel(II) and cobalt(II) from the aqeous phase to the organic phase. 相似文献
103.
Husnu Deniz Basdemir 《等离子体物理论文集》2021,61(2):e202000103
An integral theory that is associated with the scattered fields is considered for the solution of H-polarized line source diffraction by a conductive half-plane, which is surrounded by an anisotropic plasma. As the anisotropy does not affect an E-polarized incident wave, only one polarization case is considered. The cold plasma medium is characterized by the dielectric tensor. The constant external magnetic field producing the anisotropy in a cold plasma is applied parallel to the edge of the half-plane. The total, scattered, and diffracted waves are derived in terms of the Fresnel functions. Therefore, finite magnitude values at the transition boundaries are obtained. The wave behaviours are investigated numerically for different quantities of the medium. 相似文献
104.
M. Stasevych V. Zvarych V. Lunin N. G. Deniz Z. Gokmen O. Akgun 《SAR and QSAR in environmental research》2017,28(5):355-366
Anticancer activity as an associated action for a series of dithiocarbamates of 9,10-anthracenedione was predicted using the PASS computer program and analysed with PharmaExpert software. The predicted cytotoxic activity of the dithiocarbamate derivatives of 9,10-anthracenedione was evaluated in vitro on cancer cells of the human lung (A549), prostate (PC3), colon (HT29) and human breast (MCF7) using the sulforhodamine B (SRB) cell viability assay. Among these compounds, 9,10-dioxo-9,10-dihydroanthracen-1-yl pyrrolidin-1-carbodithioate and 9,10-dioxo-9,10-dihydroanthracen-2-yl pyrrolidin-1-carbodithioate were identified as the most potent anticancer agents with cytotoxic activity against the MCF-7 human breast cell line with GI50 values of 1.40 μM and 1.52 μM, whereas the GI50 value for the reference anticancer drug mitoxantrone was 3.93 μM. Thus, anticancer activity predicted by PASS with a probability Pa > 30% was confirmed by the experiment. Relatively small Pa values estimated by PASS indicated the novelty of the considered derivatives comparing to the compounds from the PASS training set. 相似文献
105.
V. M. Denisov L. T. Denisova L. G. Chumilina S. D. Kirik 《Physics of the Solid State》2013,55(7):1381-1384
The heat capacity of La2CuO4 has been measured in the temperature range 400–950 K. The temperature dependence of the heat capacity has been found to exhibit an extremum at 526 K. 相似文献
106.
Broniatowska B Allmendinger A Kaiser M Montamat-Sicotte D Hingley-Wilson S Lalvani A Guiry M Blunden G Tasdemir D 《Natural product communications》2011,6(5):689-694
Cyanobacteria (= blue-green algae) are prolific producers of structurally distinct and biologically active metabolites. In the continuation of our search for new sources of anti-infective natural products, we have assessed the in vitro antiprotozoal (Plasmodium falciparum, Trypanosoma brucei rhodesiense, T. cruzi, Leishmania donovani) and antitubercular (Mycobacterium tuberculosis) potential of samples of two terrestrial cyanobacteria, Nostoc commune (collected when desiccated and wet) and Rivularia biasolettiana. The cytotoxic potential of the extracts was also evaluated against primary L6 cells. Except for T. cruzi and M. tuberculosis, the crude extracts were active against all the organisms tested and showed no toxicity. The crude extracts were then partitioned between n-hexane, chloroform and aqueous methanol and retested against the same panel of pathogens. The chloroform sub-extracts of both N. commune samples showed significant activity against T. b. rhodesiense (IC50 values 2.0 and 3.5 microg/mL) and P. falciparum (IC50s 7.4 and 5.8 microg/mL), with low toxicity. This trend was also true for R. biasolettiana extracts, and its chloroform sub-extract showed notable activity against all parasitic protozoa. There were differences in the biological activity profiles of extracts derived from desiccated and hydrated forms of N. commune. To our knowledge, this is the first study assessing the anti-infective activity of desiccated and hydrated forms of N. commune, as well as R. biasolettiana. Furthermore, the present work reports such biological activity in terrestrial cyanobacteria from Ireland for the first time. These results warrant the further study of Irish terrestrial cyanobacteria as a valuable source of new natural product leads for the treatment of parasitic protozoal infections. 相似文献
107.
The pine leaves which are an agricultural residue were used in its natural form as biosorbent for the removal of Acid Yellow 220 (AY 220) dye from aqueous solutions. The sorption experiments were carried out as a function of solution pH, biosorbent dosage, biosorbent size, dye concentration, temperature, contact time and ionic strength. The sorption isotherms closely followed the Langmuir model. The monolayer sorption capacity of the pine leaves for AY 220 was found as 40.00 mg g− 1. It was shown that pseudo-second order equation could best describe the sorption kinetics. The thermodynamic data indicated that the sorption system was spontaneous, endothermic and physical process. Based on the results of present investigation, the pine leaves could be used as a suitable alternative biosorbent for the elimination of AY 220 from aqueous solutions. 相似文献
108.
An efficient method for simulating continuous-wave electron spin resonance spectra (ESR) of molecules labeled with two dipolar-coupled nitroxides from trajectories of the molecular motion is presented. Two approximate treatments of the dipolar spin evolution, resulting in significantly shorter simulation times, are examined in order to determine their range of applicability. The approach is illustrated in the context of a double-helical B-DNA. ESR spectra for DNA undergoing anisotropic global diffusion and internal stretching dynamics are calculated for three different labeling geometries with the spin labels bracketing, respectively, three, two and one base pairs. While multifrequency spectra of all three labeling schemes are very sensitive to DNA tumbling, the last one is found to be most informative about the local DNA dynamics. 相似文献
109.
Deniz Akta? Uygun R. Hilal ?enay Ceren Türkcan Sinan Akg?l Adil Denizli 《Applied biochemistry and biotechnology》2012,168(6):1528-1539
The purification of immunoglobulin G (IgG) from human plasma was performed by using a novel metal-chelated adsorbent with nano size. The non-porous nanoparticles were produced by surfactant free emulsion polymerization of ethylene glycol dimethacrylate (EDMA) and 2-methacryloylamidohistidine (MAH). Then, Cu(II) ions were chelated on the nanoparticles. The nano-poly(EDMA-MAH) nanoparticles were characterized by Fourier transform infrared, scanning electron microscope, atomic force microscope and elemental analysis. The non-porous nanoparticles were spherical form and have 100?C250?nm size distribution. The maximum IgG adsorption capacity of the Cu(II) chelated nanoparticles was found to be 463?mg/g polymer at pH 7.0 in HEPES buffer. Desorption of IgG was performed by 1.0?M NaCl and desorption rate was found to be 97?%. IgG was obtained from human plasma with purity of 94?% (up to 578?mg/g polymer). The non-porous nanoparticles allowed one-step purification of IgG from human plasma. 相似文献
110.
Tetrakis‐(4‐chlorophenylthio)‐butatriene (3a) and tetrakis‐(tert‐butylthio)‐butatriene (3b) were synthesized, and their crystal structures were determined. The compound 3a is monoclinic, space group P21/c, a=6.9785(8), b=8.6803(9), c=22.884(2) Å, β=93.887(6)o, V=1383.0(3) Å3, Z=2. The compound 3b is monoclinic, space group P21/n, a=11.0615(6), b=10.8507(4), c=11.2717(6) Å, β =116.427(2)o, V=1211.5(1) Å3, Z=4. The title compounds 3a and 3b reside on an inversion center so that only half of the molecule is crystallographically unique. Both compounds are not planar. The crystal structures of 3a and 3b have cumulated double bonds. The C7–C8–C8i and C5–C6–C6i angles that show the linearity in both structures, respectively, are 176.4(3)° in 3a and 175.6(2)° in 3b. 相似文献