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61.
An alkalophilic, chitinase-producing Bacillus sp. BG-11 was isolated which produced an extracellular chitinase and which was purified 16.5-fold, using standard purification techniques. The purified chitinase exhibited a broad pH and temperature optima of 7.5-9.0 and 45 deg C-55 deg C, respectively. The chitinase was stable between pH 6.0-9.0 and 50°C for more than 2 h. Half lives of enzyme at 60 deg C, 70 deg C and 80 deg C were 90 min, 30 min and 20 min respectively. Km value was 12 mg chitin per ml. Shelf life was 60 days at 4°C. Ca2+, Ni2+ and Triton-X-100 stimulated the activity up to 20% whereas Ag+, Hg2+, dithiothreitol, -mercaptoethanol, glutathione, iodoacetic acid and iodoacetamide inhibited the activity up to 50%. 相似文献
62.
The effects of pump speed, cumulative permeate volume and concentration of feed (yeast cells) on the permeate flux have been studied on a batch cross-flow microfiltration process. The experiments were conducted for two different cellulose acetate membrane modules of 0.2 m and 0.45 m pore size. A three factor experiment was designed for this purpose and the effect of the operating parameters on the filtration rate was studied by the analysis of variance (ANOVA). It is concluded from the analysis of the experimental data that pump speed has the maximum bearing upon the permeate rate within the operating range of parameters. Fouling conditions were examined in the light of colloids deposition on membranes due to surface interactions. However this paper looks into the relationship and sensitivity of the operating parameters in a cross-flow microfiltration unit rather than exploring the theoretical principles behind the observed phenomena.This revised version was published online in October 2005 with corrections to the Cover Date. 相似文献
63.
A subunit of molecular weight 18300 has been separated and isolated from seeds of Brassica campestris L. This subunit was cleaved by using cyanogen bromide, trypsin, Staphylococcus aureus V8 protease and chymotrypsin; the fragments obtained from enzymatlc and chemical cleavages were separated and isolated by polyacrylamide gel electrophoresis and gel filtration. The amino acid analyses were carried out. The complete amino acid sequence of the subunit containing 172 amino acid residues has been established by manual Edman method. 相似文献
64.
R. Bhushan G. Thuku Thiongo 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1998,708(1-2)
The resolution of (±)-atenolol, (±)-propranolol and (±)-metoprolol into their enantiomers was achieved by TLC on silica-gel plates impregnated with optically pure
-lysine (0.5%) and
-arginine (0.5%) as the chiral selectors. In all cases, different combinations of acetonitrile–methanol solvent systems were found to be successful in resolving these compounds. Spots were detected using iodine vapour. The detection limit for both (±)-atenolol and (±)-propranolol was 2.6 μg and for (±)-metoprolol, it was 0.26 μg. 相似文献
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65.
Sigamani Ashokkumar Arunai Nambiraj Sujit Nath Sinha Girigesh Yadav Kothanda Raman Manindra Bhushan Rajesh Thiyagarajan 《Reports of Practical Oncology and Radiotherapy》2015,20(3):170-180
Aim
To measure and compare the head scatter factor for 7 MV unflattened and 6 MV flattened photon beam using a home-made designed mini phantom.Background
The head scatter factor (Sc) is one of the important parameters for MU calculation. There are multiple factors that influence the Sc values, like accelerator head, flattening filter, primary and secondary collimators.Materials and methods
A columnar mini phantom was designed as recommended by AAPM Task Group 74 with high and low atomic number material for measurement of head scatter factors at 10 cm and dmax dose water equivalent thickness.Results
The Sc values measured with high-Z are higher than the low-Z mini phantoms observed for both 6MV-FB and 7MV-UFB photon energies. Sc values of 7MV-UFB photon beams were smaller than those of the 6MV-FB photon beams (0.6–2.2% (Primus), 0.2–1.4% (Artiste) and 0.6–3.7% (Clinac iX (2300CD))) for field sizes ranging from 10 cm × 10 cm to 40 cm × 40 cm. The SSD had no influence on head scatter for both flattened and unflattened beams. The presence of wedge filters influences the Sc values. The collimator exchange effects showed that the opening of the upper jaw increases Sc irrespective of FF and FFF.Conclusions
There were significant differences in Sc values measured for 6MV-FB and unflattened 7MV-UFB photon beams over the range of field sizes from 10 cm × 10 cm to 40 cm × 04 cm. Different results were obtained for measurements performed with low-Z and high-Z mini phantoms. 相似文献66.
A purification process for heparin and precursor polysaccharides using the pH responsive behavior of chitosan 下载免费PDF全文
Ujjwal Bhaskar Anne M. Hickey Guoyun Li Ruchir V. Mundra Fuming Zhang Li Fu Chao Cai Zhimin Ou Jonathan S. Dordick Robert J. Linhardt 《Biotechnology progress》2015,31(5):1348-1359
The contamination crisis of 2008 has brought to light several risks associated with use of animal tissue derived heparin. Because the total chemical synthesis of heparin is not feasible, a bioengineered approach has been proposed, relying on recombinant enzymes derived from the heparin/HS biosynthetic pathway and Escherichia coli K5 capsular polysaccharide. Intensive process engineering efforts are required to achieve a cost‐competitive process for bioengineered heparin compared to commercially available porcine heparins. Towards this goal, we have used 96‐well plate based screening for development of a chitosan‐based purification process for heparin and precursor polysaccharides. The unique pH responsive behavior of chitosan enables simplified capture of target heparin or related polysaccharides, under low pH and complex solution conditions, followed by elution under mildly basic conditions. The use of mild, basic recovery conditions are compatible with the chemical N‐deacetylation/N‐sulfonation step used in the bioengineered heparin process. Selective precipitation of glycosaminoglycans (GAGs) leads to significant removal of process related impurities such as proteins, DNA and endotoxins. Use of highly sensitive liquid chromatography‐mass spectrometry and nuclear magnetic resonance analytical techniques reveal a minimum impact of chitosan‐based purification on heparin product composition. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:1348–1359, 2015 相似文献
67.
68.
Bioavailability and metabolism of fucoxanthin in rats: structural characterization of metabolites by LC-MS (APCI) 总被引:1,自引:0,他引:1
Ravi Kumar Sangeetha Narayan Bhaskar Sounder Divakar Vallikannan Baskaran 《Molecular and cellular biochemistry》2010,333(1-2):299-310
This study reports bioavailability and metabolism of fucoxanthin (FUCO) from brown algae Padina tetrastromatica in rats. Rats were divided into two groups (n = 25/group). Group one was fed basal diet (control) while the group two received retinol deficient diet (RD group) for 8 weeks. After confirmed RD in blood (0.53 μmol/l), rats were further sub-grouped (n = 5/sub group), intubated a dose of FUCO (0.83 μmol) and killed after 0, 2, 4, 6 and 8 h. The plasma levels (area under curve/8 h) of FUCO (fucoxanthinol (FUOH) + amarouciaxanthin (AAx)) was 2.93 (RD group) and 2.74 pmol/dl (control), respectively. No newly formed retinol was detected in RD rats intubated with FUCO. Besides FUOH (m/z 617 (M+H)+) and AAx (m/z 617 (M+H?)+), other deacetylated, hydrolyzed and demethylated metabolites of bearing molecular mass at m/z 600.6 (FUOH–H2O), m/z 597 (AAx–H2O), m/z 579 (AAx–2H2O+1), m/z 551 (AAx–2H2O–2CH3+2) and m/z 523 (AAx–2H2O–4CH3+4) were also detected in plasma and liver by LC-MS (APCI). Although biological functions of FUCO metabolites need thorough investigation, this is the first detailed report on FUCO metabolites in rats. 相似文献
69.
Soil nitrogen and microbial biomass carbon dynamics in native forests and derived agricultural land uses in a humid tropical climate of India 总被引:1,自引:0,他引:1
Sedum alfredii, a cadmium (Cd) and zinc (Zn) hyperaccumulator at a mine located in Qu Zhou City, Zhejiang Province, China, can accumulate Cd and Zn exceeding 1,000 and 10,000 mg kg?1, respectively in its shoot (dry weight) when growing under metal-contaminated habitats. Several strains of bacteria were isolated from the rhizosphere of S. alfredii thriving in different Pb/Zn mines in Hunan Province and Zhejiang Province, China, which can resist high levels of heavy metals. Among the different strains isolated, Burkholderia cepacia showed the highest ability in mobilizing Cd and Zn as well as resisting high concentrations of soluble Zn (500 mg L?1). The soluble Zn concentration in the medium increased from 13 to 72 and 99% (p?<?0.001) after bacterial inoculation in the medium supplemented with insoluble zinc oxide and zinc carbonate, respectively, while pH dropped from 7 to 2.93. The soluble Cd concentration was also increased from 8 to 96% (p?<?0.001), and pH decreased from 7 to 2.65. Short-chain organic acids were also analyzed and the results indicated that oxalic acid, tartaric acid, formic acid and acetic acid had a significant correlation (p?<?0.001) with the concentrations of Cd and Zn being mobilized during the assay. The present results implicated that certain bacteria associated with metal hyperaccumulators could contribute significantly in mobilizing heavy metals, which would enhance the phytoextraction process. 相似文献
70.
Thanemozhi G Natarajan Bhaskar V Kallakury Christine E Sheehan Margaret B Bartlett Natarajan Ganesan Anju Preet Jeffrey S Ross Kevin T FitzGerald 《Cancer cell international》2010,10(1):13