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801.
802.
Dongmei Cha Dong’e Cheng Mingming Liu Zhaorui Zeng Xiaowei Hu Wenwu Guan 《Journal of chromatography. A》2009,1216(9):1450-1457
A method based on solid-phase microextraction (SPME) and post-derivatization on the fiber coupled to gas chromatography–mass spectrometry (GC–MS) was developed for the analysis of fatty acids in sputum from patients with pulmonary tuberculosis. The sputum specimens were digested, hydrolyzed, extracted, derivertized, injected and analyzed without cultivation or isolation of the microorganism. Under optimized conditions, the relative standard deviations (RSD, n = 5) for all analytes were below 17% and the limits of detection varied from 1.68 (C24:0) to 150.4 μg L−1 (C12:0). Good linearity was observed for all the fatty acids studied except for C12:0 within a wide concentration range of three orders of magnitudes with the correlation coefficients ranging from 0.91 (C24:0) to 0.99 (C14:0). Fatty acids in sputum specimens from 21 persons were directly analyzed using the proposed method. The results show that in all the sputum specimens from patients, who were clinically diagnosed with tuberculosis (TB), tuberculosis stearic acid (TBSA) was detected, while in all the sputum samples from persons without TB, TBSA was not found. The possibility of using the proposed method to detect mycobacterium tuberculosis (MTB) via the identification of TBSA in sputum was discussed. The comparison with other methods including sputum culture and microscopy of direct smears indicated that the proposed method is fast and sensitive for the analysis of fatty acids in sputum and offers an alternative for the detection of MTB in sputum. 相似文献
803.
Liang Li Chang‐Yun Wang Chang‐Lun Shao Yue‐Wei Guo Guo‐Qiang Li Xue‐Ping Sun Lei Han Hui Huang Hua‐Shi Guan 《Helvetica chimica acta》2009,92(8):1495-1502
Chemical examination of the soft coral Sarcophyton infundibuliforme collected from the South China Sea resulted in the isolation of the three new O‐glycosylglycerol derivatives sarcoglycosides A–C ( 1 – 3 ), together with two known compounds, chimyl alcohol ( 4 ) and hexadecanol ( 5 ). Their structures were elucidated by combined spectral and chemical methods. All the compounds showed moderate toxicity to brine shrimps Artemia salina. 相似文献
804.
一维铁磁金属纳米材料的制备、结构调控及其磁性能 总被引:2,自引:0,他引:2
樊希安|官建国|王维|王一龙|童国秀|牟方志 《化学进展》2009,21(1):143-151
一维铁磁金属纳米材料不但具有普通纳米粒子的各种特殊效应,而且具有独特的形状各向异性和磁各向异性,是构筑新型电磁功能材料的重要组元,在高密度磁记录、敏感元器件、电磁波吸收、催化剂、医学和生物功能材料等领域具有重要的应用。本文以一维铁磁金属纳米材料的制备技术为评述线索,重点论述了一维铁磁金属纳米材料的形貌参数(包括直径、长度、长径比),晶面取向等微观结构的调控方法以及结构对磁性能的影响规律,指出发展新型的一维铁磁纳米材料的结构控制方法,研究一维材料的定向排布及组装技术,并从更深层次揭示一维结构与性能的关系以及开发一维铁磁纳米材料在各领域的实际应用是未来研究的主要发展方向。 相似文献
805.
A novel amperometric immunosensor based on L ‐cysteine/nanosized Prussian blue bilayer films ({NPB/L ‐cys}2) and gold nanoparticles (nano‐Au) was fabricated for determination of human chorionic gonadotrophin (HCG). First, L ‐cys and NPB was self‐assembled by layer‐by‐layer (LBL) technology to form {NPB/L ‐cys}2 bilayer films on the gold electrode. Subsequently, nano‐Au layer was immobilized on the {NPB/L ‐cys}2 bilayer films by electrodepositing gold chloride tetrahydrate and then anti‐HCG was assembly on the nano‐Au layer. Finally hemoglobin (Hb) was employed to block sites against nonspecific binding. With the electrocatalytic ability of Hb and NPB for the reduction of H2O2, the current signal of the antigen‐antibody reaction was amplified and the enhanced sensitivity was achieved. In this study, the assembly process and performance of the immunosensor were characterized by cyclic voltammetry (CV) and the morphology was researched by scanning electron microscopy (SEM). The immunosensor performed a high sensitivity and a wide linear response to HCG in two ranges from 0.5 to 10 mIU/mL and from 10 to 200 mIU/mL with a relatively low detection limit of 0.2 mIU/mL at 3 times the background noise, as well as good stability and long‐term life. 相似文献
806.
Jing Guan Xiujie Li Gang Yang Weiping Zhang Xianchun Liu Xiuwen Han Xinhe Bao 《Journal of molecular catalysis. A, Chemical》2009,310(1-2):113-120
The local structures of various Brønsted and Lewis acid sites in H-Beta zeolite were resolved with the combined 31P MAS NMR, 31P–27Al TRAPDOR NMR experiments and theoretical calculations at different levels. In addition, the interacting mechanisms of these acid sites with probe molecules such as trimethylphosphine (TMP) and trimethylphosphine oxide (TMPO) were clarified, which greatly aids the understanding of acid catalysis. Owing to the narrow chemical shift range and close Brønsted acid strengths, only an average resonance at −4.5 ppm was observed in TMP adsorbed H-Beta zeolite, consistent with the calculated data of acidities (substitution energies and proton affinities), geometries, adsorption energies as well as 31P chemical shifts. However, two types of Brønsted acids were distinguished by TMPO, and the HF/DZVP2 (MP2/DZVP2) chemical shifts were calculated at 68.1 (69.5) and 69.7–72.1 (71.7–74.9) ppm, respectively. Two types of Lewis acids were identified at −32.0 and −47.0 ppm with the latter exhibiting strong 31P–27Al TRAPDOR effects. With theoretical calculations, these two peaks were attributed to the extra-lattice oxo-AlOH2+ species and the three-fold coordinated lattice-Al, extra-framework Al(OH)3, oxo-AlO+ species, respectively. The peak at −60.0 ppm was conventionally assigned to the TMP physisorption, but the calculations indicated that the EFAL monovalent Al(OH)2+ species coordinating with two lattice-O atoms near the framework Al atom can contribute to it as well. 相似文献
807.
Sen Hou Xin-Xin Li Xiao-Yu Li Xi-Zeng Feng Li Guan Yan-Lian Yang Chen Wang 《Analytical and bioanalytical chemistry》2009,394(8):2111-2117
Controllable cell growth on the defined areas of surfaces is important for potential applications in biosensor fabrication
and tissue engineering. In this study, controllable cell growth was achieved by culturing 293 T fibroblast cells on a mica
surface which had been patterned with collagen strips by a microcontact printing (μCP) technique. The collagen area was designed
to support cell adhesion and the native mica surface was designed to repel cell adhesion. Consequently, the resulting cell
patterns should follow the micro-patterns of the collagen. X-ray photoelectron spectroscopy (XPS), water contact angle (WCA)
measurement, atomic-force microscope (AFM) observation, and force-curve measurement were used to monitor property changes
before and after the collagen adsorption process. Further data showed that the patterned cells were of good viability and
able to perform a gene-transfection experiment in vitro. This technique should be of potential applications in the fields
of biosensor fabrication and tissue engineering.
Figure Controllable cells growth has been achieved by culturing 293T fibroblast cells on the mica surface which had been patterned
with collagen strips by microcontact printing (μCP) technique 相似文献
808.
Guan‐Hua Wang Zhi‐Gang Li Heng‐Qing Jia Ning‐Hai Hu Jing‐Wei Xu 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(9):m333-m336
In the mixed‐metal complex catena‐poly[bis[diaquasilver(I)] [bis[aquacopper(II)]‐μ3‐pyridine‐2,5‐dicarboxylato‐2′:1:1′κ5N,O2:O5:O5,O5′‐μ‐pyridine‐2,5‐dicarboxylato‐2:1κ4N,O2:O5,O5′‐disilver(I)‐μ3‐pyridine‐2,5‐dicarboxylato‐1:1′:2′′κ5O5,O5′:O5:N,O2‐μ‐pyridine‐2,5‐dicarboxylato‐1′:2′′′κ4O5,O5′:N,O2] hexahydrate], {[Ag(H2O)2][AgCu(C7H3NO4)2(H2O)]·3H2O}n, a square‐pyramidal CuII center is coordinated by two N atoms and two O atoms from two pyridine‐2,5‐dicarboxylate (2,5‐pydc) ligands and a water molecule, forming a [Cu(2,5‐pydc)2(H2O)]2− metalloligand. One AgI center is coordinated by five O atoms from three 2,5‐pydc ligands and, as a result, the [Cu(2,5‐pydc)2(H2O)]2− metalloligands act as linkers in a unique μ3‐mode connecting AgI centers into a one‐dimensional anionic double chain along the [101] direction. The other AgI center is coordinated by two water molecules, forming an [Ag(H2O)2]+ cation. Four adjacent AgI centers are associated by Ag...Ag interactions [3.126 (1) and 3.118 (1) Å], producing a Z‐shaped Ag4 unit along the [010] direction and connecting the anionic chains into a two‐dimensional layer structure. This study offers information for engineering mixed‐metal complexes based on copper(II)–pyridinedicarboxylate metalloligands. 相似文献
809.
Yan Ling Wang Bao Yu Guo Guan Cheng Jiang Xiu Tai Zhao Ye Fei Wang Jing Jing Zheng Li Ma 《Journal of chemical crystallography》2011,41(3):312-315
Abstract
A new crystal of tetraphenylphosphonium bis(2-thioxo-1,3-dithiole-4,5-dithiolato)-nickelate acetone solvate (BPNI) has been prepared at room temperature and characterized by elemental analysis, UV–Vis–NIR absorption spectrum and X-ray single crystal determination. The complex crystallized in monoclinic space group P2/c with unit cell dimensions a = 24.5350 (6) ?, b = 7.3097 (2) ?, c = 23.1141 (6) ?, β = 115.585 (2)°, V = 3738.89 (17) ?3, Z = 4, D x .= 1.5081 (1) g cm−3. The X-ray structure determination revealed that the crystal is centro-symmetrical and there are two halves of independent cations in the molecule. 相似文献810.
In this paper, a simple repairable system (i.e. a one-component repairable system with one repairman) with preventive repair and failure repair is studied. Assume that the preventive repair is adopted before the system fails, when the system reliability drops to an undetermined constant R , the work will be interrupted and the preventive repair is executed at once. And assume that the preventive repair of the system is “as good as new” while the failure repair of the system is not, and the deterioration of the system is stochastic. Under these assumptions, by using geometric process, we present a bivariate mixed policy (R,N), respectively based on a scale of the system reliability and the failure-number of the system. Our aim is to determine an optimal mixed policy (R,N)∗ such that the long-run average cost per unit time (i.e. the average cost rate) is minimized. The explicit expression of the average cost rate is derived, and the corresponding optimal mixed policy can be determined analytically or numerically. Finally, a numerical example is given where the working time of the system yields a Weibull distribution. Some comparisons with a certain existing policy are also discussed by numerical methods. 相似文献