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951.
As a kind of ammonia‐oxidizing bacteria, Nitrosomonas europaea (N. europaea) was chosen as a research model to study the alteration of cell membrane in the presence of tourmaline and biodegradation of acetochlor. atomic force microscopy images reveal that the presence of tourmaline substantially changes the structure of the outer membrane of the cell responsible for the cell permeability. SEM images show that the introduction of tourmaline makes the cell lose its ability to resist lysozyme owing to the damages. The fluorescence polarization has shown a significant decrease in membrane fluidity and the increase of permeability of cell membrane. Ca2+ and Mg2+ was measured using inductively coupled plasma mass spectrometry and was found in the supernatant from the cells treated by tourmaline. Tourmaline can improve the efficiency of biodegradation of acetochlor for N. europaea. It is proposed that the cell permeability is slightly increased, and the absorbability of nutrition from the medium becomes easier. As a result, N. europaea grows faster in the presence of tourmaline than the native cells. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
952.
Determination of ascorbic acid and its degradation products by high‐performance liquid chromatography‐triple quadrupole mass spectrometry 下载免费PDF全文
Małgorzata Szultka Magdalena Buszewska‐Forajta Roman Kaliszan Bogusław Buszewski 《Electrophoresis》2014,35(4):585-592
This study describes application of liquid chromatography coupled with triple quadrupole mass spectrometry (LC‐MS) for evaluation of vitamin C stability, the objective being prediction of the degradation products. Detection was performed with an UV detector (UV‐Vis) in sequence with a triple‐quad mass spectrometer in the multiple reaction mode. The negative ion mode of ESI and MS‐MRM transitions of m/z 175→115 (quantifier) and 175→89 (qualifier) for ascorbic acid was used. All the validation parameters were within the range of acceptance proposed by the Food and Drug Administration. The method was fully validated in terms of linearity, LOD, LOQ, accuracy, and interday precision. Validation experiments revealed good linearity with R2 = 0.999 within the established concentration range, and excellent repeatability (9.3%). The LOD of the method was 0.1524 ng/mL whereas the LOQ was 0.4679 ng/mL. LC‐MS methodology proves to be an improved, simple, and fast approach to determining the content of vitamin C and its degradation products with high sensitivity, selectivity, and resolving power within 6 minutes of analysis. 相似文献
953.
A general and efficient P(V)–N activation method for the preparation of symmetrical and asymmetrical dinucleoside polyphosphates (NpnN′s, n=2–4) and P2,P3-CX2-dinucleoside tetraphosphates (X=H, F, and Cl) has been established. Twenty-two dinucleoside polyphosphates and their phosphonate analogs were synthesized from nucleoside 5′-phosphoropiperidates with 4,5-dicyanoimidazole as the activator in good to high yields. 相似文献
954.
Changtao Ji Qi Chen Qinglian Li Hongbo Huang Yongxiang Song Junying Ma Jianhua Ju 《Tetrahedron letters》2014
McbA was characterized in vitro as a novel amide synthetase in the marinacarbolines A–D biosynthetic pathway, catalyzing amide bond formation between 1-acetyl-3-carboxy-β-carboline (1a) and substituted-β-phenethylamines (1b, 2b, 3b) and tryptamine (4b) in an ATP-dependent manner. Enzyme kinetic analyses highlight β-phenethylamine as the most suitable amine donor. McbA showed broad substrate compatibility with substituted amines; 10 new β-carboline analogues were chemoenzymatically generated. 相似文献
955.
The in situ synthesis and subsequent reactions of macrocylic imine 2 are reported. The imine was trapped with cyanotrimethylsilane to give α-amino nitrile aza-[13]-macrodiolides in a 1:1 ratio of diastereomers. A crystal structure of the syn α-cyano nitrile diastereomer, 7a, provided insights into the lack of selectivity in reactions of 2 relative to macrocyclic alkene 1. Reactions to functionalize the syn diastereomer 7a are also reported. 相似文献
956.
Zhi Zeng Jian Su Hao Ma Hengguan Yi Jianping Cheng Qian Yue Junli Li Hui Zhang 《Journal of Radioanalytical and Nuclear Chemistry》2014,301(2):443-450
To determine the environmental gamma background levels which affects rare events experiments, we measured in situ gamma spectrum at four locations in the China Jinping Underground Laboratory. The integral background count rates (40–2,700 keV) varied from 3.76 to 74.1 cps. The average count rate of the measurements inside the CJPL was 73.4 cps. The spectrometer was calibrated with a 152Eu point source and Monte Carlo simulation to obtain the activity conversion factors for the rock and the air, respectively. The rocks that surrounded the CJPL was characterized by very low activity concentrations of 238U (3.69–4.21 Bq kg?1), 232Th (0.52–0.64 Bq kg?1) and 40K (4.28 Bq kg?1). 相似文献
957.
Yufei Ma Sheng Liang Hua Wu Hui Wang 《Journal of Radioanalytical and Nuclear Chemistry》2014,299(3):1865-1870
The successes of noninvasive methods to visualize and quantify integrin αvβ3 expression in vivo have paved the way for radiolabeling anti-integrin therapy in clinic. Arginine-glycine-aspartice (RGD) peptide and related derivatives labeled with radionuclides for radio-therapy, which specifically targeting integrin αvβ3-positive tumors, could be used to treat these tumors. We have labeled c(RGDyK)-His, a RGD derivative, with 188Re and the radio-therapy efficiency has been evaluated in model nude mice. c(RGDyK)-His was labeled with 188Re by chelating with [188Re(CO)3(H2O)3]+ under a slightly basic condition. The in vitro specific binding affinity to U87 MG cell lines and the biodistribution of 188Re-c(RGDyK)-His in the animal tumor models was measured. The inhibitory effects of 188Re-c(RGDyK)-His were observed more than 1 month, and evaluated by microPET/CT imaging with 18F-FDG. Results of in vivo, cell uptake demonstrated 188Re-c(RGDyK)-His had a high specific binding affinity to receptor integrin αvβ3. In biodistribution experiment, 188Re-c(RGDyK)-His was accumulated in the tumor and cleared fast from the normal tissues. In radiotherapy study, tumor growth inhibition was significantly higher in the treatment groups than in the control groups. These studies showed that 188Re-c(RGDyK)-His could be effectively used for integrin αvβ3 targeting therapy. This may offer a potential therapeutic strategy for the treatment of integrin-positive tumors in clinic. 相似文献
958.
为寻找具有更高生物活性、更环保的新农药杀菌剂,基于杀菌剂氟咯菌腈设计并合成了10个新型吡唑联吡咯类杂环化合物,以吡唑环代替氟咯菌腈上原有的苯环,以期提高其杀菌活性.采用1H NMR,FTIR,单晶X射线衍射、元素分析和熔点测定等测试手段对目标化合物及其中间体的结构进行了表征与确认,并通过挥发法培养得到了6个目标化合物的单晶.还对其中6个化合物进行了生物活性测试,测试结果表明各化合物对水稻纹枯病、黄瓜灰霉病、黄瓜霜霉病均表现出一定的抑菌效果,可作为先导化合物对其结构进行深入的研究,为新农药杀菌剂的开发提供了理论支持. 相似文献
959.
960.
Fang Li Hongfang Ma Haitao Zhang Weiyong Ying Dingye Fang 《Comptes Rendus Chimie》2014,17(11):1109-1115
The catalytic hydrogenation of CO was studied over Mn- and/or Fe-promoted Rh/γ-Al2O3 catalysts. The catalysts were characterized by means of XRD, BET, H2-TPR·H2-TPD, XPS and DRIFTS. CO hydrogenation results showed that the doubly Mn- and Fe-promoted Rh/γ-Al2O3 catalysts exhibited superior catalytic activity and better ethanol selectivity. The DRIFTS results showed that Mn promoter stabilized the adsorbed CO on Rh+ and Fe stabilized adsorbed CO on Rh+ and Rh0, especially Rh0. The fact that doubly Mn- and Fe-promoted Rh/γ-Al2O3 owned more (Rhx0–Rhy+)–O–Fe3+·(Fe2+) active species was proposed to be a crucial factor accounting for its higher ethanol selectivity. 相似文献