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991.
S. A. Wasay W. Parker P. J. Van Geel S. Barrington S. Tokunaga 《Soil & Sediment Contamination》2000,9(1):51-64
A study was conducted to assess the retention form of arsenic in soil and to evaluate the use of phosphate for releasing it from the soil. In this study, a loam soil was artificially polluted with arsenate at pH 5.5, which is one of the pH values at which maximum arsenic adsorption occurred. The soil was kept for 2.5 months under wet conditions to allow for stabilization. The soil was maintained under aerobic condition and losses of arsenic by volatilization were determined to be minimal. The soil was then sequentially extracted with a series of chemicals to identify the soil fractions in which the arsenic was bound. The percentage of arsenic found in the Fe bound-exchangeable, reducible-residual, Al bound exchangeable, residual, calcium bound exchangeable, and easily exchangeable forms was 31.6, 27.3, 25.2, 5.5, 4.9, and 4.7%, respectively. A batch experiment showed that at 20°C, 80% of the bound arsenic was removed by phosphate in the pH range of 5 to 7. A power function model was found to fit the data with a desorption rate constant of 402?mg/kg As h?1. 相似文献
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993.
改良尿素-氯化锂方法提取成熟小麦种子总RNA 总被引:22,自引:0,他引:22
为了分离提取成熟小麦种子总RNA,去除多糖等杂质的严重干扰,本实验对尿素氯化锂分离RNA的方法做了三个方面的改进:一、去除成熟种子的胚(含大量麦胚凝集素等糖蛋白),发现裂解物的黏稠度明显下降;二、在裂解粗提物中加入CTAB至终浓度为02%,可去除大部分多糖;三、异丙醇沉淀RNA之后,充分溶解,离心去除残留的不溶性多糖等杂质。结果表明:所提取的成熟小麦种子RNA的纯度和产率都有明显提高 。 相似文献
994.
黑麂粪便DNA提取及其PCR检测 总被引:6,自引:1,他引:5
采集了黑麂(Muntiacus crinifrons)的新鲜粪便以及在野外自然条件下保存较长时间的粪便样品,晾干后带回实验室,提取其DNA;同时提取黑麂肌肉、皮张样品的DNA,用以对比粪便样品的提取效果。电泳检测结果显示,此方法使用实验室中常用的分子生物学试剂,可以从黑麂粪便样品中抽提到高质量的粪便DNA并克服分子粪便学研究中常见的PCR反应抑制物的影响。为其它濒危鹿科动物的非损伤性取样提供了的新途径,为其遗传结构、遗传多样性现状等研究提供了更加广阔的取材空间。 相似文献
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998.
Haobin Hu Haipeng Liang Yufeng Wang Runan Yuan Jiao Sun Lala Zhang Yani Lu 《化学与生物多样性》2021,18(6):e2000947
The ultrasound-assisted extraction (UAE) parameters of total water-soluble polysaccharides (TABPs) from Acanthopanaxbrachypus fruit were optimized by Box-Behnken design (BBD) and response surface methodology (RSM). Physicochemical, structural, and functional properties of TABPs were investigated by chemical analysis, inductively coupled plasma optical emission spectrometry (ICP-OES), high performance liquid chromatography (HPLC), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), water-holding capacity (WHC), oil-holding capacity (OHC), emulsion capacity (EC), emulsion stability (ES), as well as DPPH. and ABTS.+scavenging assays. The results showed that the maximal UAE-yield of TABPs was 3.81±0.18 % under the optimal conditions (ultrasonic power 325 W, extraction temperature 47 °C, extraction time 22 min). TABPs was rich in some beneficial element (Mg, K, Fe, Zn and Na) but little in harmful elements (Hg, Cd, As and Pb), and displayed rough surface with flake-like features and large dents, contained 93.89±0.08 % of total carbohydrate with more different monosaccharides including glucose, galactose, rhamnose, arabinose, mannose, xylose, and uronic acid in a molar ratio of 8.83 : 7.90 : 4.74 : 4.55 : 2.80 : 2.39 : 1.00, respectively. TABPs exhibited broad weight distribution (11.2–133.5 kDa), excellent thermal stability (>280 °C), WHC (0.61±0.08 g water/g sample) and OHC (4.53±0.12 g oil/g sample), as well as higher EC (43.75±1.23 %) and ES (38.32±1.50 %). Furthermore, TABPs also displayed remarkable scavenging activities on DPPH. and ABTS.+ in vitro. These findings provide a scientific basis for the applications of TABPs in functional additives for food, medicine, and cosmetics. 相似文献
999.
Efficient lipase-selective synthesis of dilauryl mannoses by simultaneous reaction–extraction system
Wenbin Zhang Yinjiao Wang Khizar Hayat Xiaoming Zhang Abbas Shabbar Biao Feng Chengsheng Jia 《Biotechnology letters》2009,31(3):423-428
An efficient method for enzymatic-selective synthesis of dilauryl mannoses was developed using lipase-catalyzed condensation
of d-mannose and lauric acid in a simultaneous reaction–extraction system. The highest equilibrium conversion of diesters of 51%
(1,6-diester: 14%; 3,6-diester: 18%; 4,6-diester: 19%) and the total conversion of mono and dilauryl mannoses of 76% were
achieved at the n-hexane/acetonitrile ratio of 1:1, the molar ratio of lauric acid to mannose of 4:1, 60 g/l molecular sieves and 5 g/l lipase
at 50°C for 72 h in 15 ml SRE system. The new system will be important for the synthesis of dilauryl mannoses. 相似文献
1000.
Here we report a new method for oxosteroid identification utilizing “tandem mass tag hydrazine” (TMTH) carbonyl-reactive derivatisation reagent. TMTH is a reagent with a chargeable tertiary amino group attached through a linker to a carbonyl-reactive hydrazine group. Thirty oxosteroids were analysed after derivatisation with TMTH by electrospray ionization mass spectrometry (ESI-MS) and were found to give high ion-currents compared to underivatised molecules. ESI-tandem mass spectrometry (MS/MS) analysis of the derivatives yielded characteristic fragmentation patterns with specific mass reporter ions derived from the TMT group. A shotgun ESI-MS method incorporating TMTH derivatisation was applied to a urine sample. 相似文献