白术多糖的分离纯化与结构表征

采用UV, IR, NMR, GC-MS, 高碘酸氧化和Smith降解等物理化学方法对从白术根茎提取的白术多糖的纯度、理化性质和结构进行了表征. 以中药白术的根茎为原料, 通过热水(80 ℃)浸提和乙醇醇沉得到粗多糖, 再经DEAE-52阴离子交换柱层析分离和Sephadex G-200凝胶柱层析纯化, 得到一种水溶性的白术多糖(WAM). 经高效液相色谱(HPLC)分析, 多糖WAM是分子量约为3263的均一多糖. GC分析表明, WAM是由葡萄糖和半乳糖以摩尔比3.01:1构成的杂多糖. 甲基化分析、高碘酸氧化、Smith降解、部分酸水解、NMR和IR等分析结果表明, WAM具有多分支结构, 主链由β-D-1→3和β-D-1→3,6吡喃葡萄糖构成, 每个重复单元具有一个支链, 支链由β-D-半乳糖构成, 连接在主链葡萄糖的6位碳原子上.     

Intelligent active vibration control in an isolation platform

This paper presents the study on the vibration attenuation in an isolated platform by combining multi-layer perception (MLP) neural network, radial basis function (RBF) neural network, cerebella model articulation controller (CMAC) neural network and fuzzy neural networks (FNN) with error back propagation algorithm to control voice coil actuator. Usually, the methods in past time to control vibration were mainly designed by using mathematical models, which must be nearly close to the actual plant models. As regards to these utilized control methods, the most important advantage of them are that they have capability of self tuning the parameters of controllers and could adapt the changes of the environments. The performance of attenuation and control effectiveness can be evaluated by placing the accelerator to measure the amplitude at the center of the isolated platform. The experimental results in this study show that the control methods as adopted could greatly attenuate the vibration of resonance and external disturbance in an isolation platform.     

海绵Phyllospongia Foliascens中的双高Scalarane二倍半萜

具有Scalarane碳架的二倍半萜以及C-20单甲基化或C-20和C-24双甲基化的Scalarane型高二倍半萜普遍存在于Dictyoceratida科海绵中,我们从同科海绵Phyllospongia foliascens中已分离及测定了5个结构新颖的双高二倍半萜,本文报道另外2个双高二倍半萜phyllohemiketal A(1)和B(2)的分离和结构测定。     

聚合体改性微孔膜的制备及其在生化分离中的应用

聚乙烯制成微孔泡沫膜具有庞大面积，通过接枝挂上羟基，胺基成为工在质膜，再进而与乙烯基二甲基内酯枝为改性膜，它在中性缓冲液中能与蛋白质－Ａ的氨基产生配位而吸着，于酸性液解离，利用这种配位，亲和性，螯合作用在物化条件转弯下的可逆过程，能分离提纯细菌蛋白质，金属化合物和有机色质。     

酱香型酒香气成分研究3．珍酒、茅台酒前香成分的分离及气相色谱／质谱分析

用Ｎ２吹扫－冷凝方法分离、收集珍酒、茅台酒的前香。收集液经过感官评定，确认为珍酒、茅台酒的前香。用气相色谱／质谱联用方法研究它们的化学组成。鉴定了１２种化合物，并测定了它们的相对含量。     

Methodology for isolating drug metabolites from biological fluids by HPLC

This article presents a detailed account of the isolation of drug metabolites from bile by reverse-phase HPLC. The systematic approach is illustrated for the metabolism of butoprozine, a new antianginal drug, in the dog. Separation utilizes isocratic and gradient elution. Detection of the metabolites in. the presence of endogenous bile components is accomplished by very selective radioactivity measurements, by less selective UV (single wavelength) detection, and by much more universal detection modes such as on-line UV spectroscopy and off-line mass- and nuclear magnetic resonance spectroscopy. The importance of the latter three techniques in purity analysis of isolated metabolites is illustrated.     

Reactions of Silicon Atoms with Methanol: A Combined Matrix‐Spectroscopic and Density Functional Theory Study

The reaction of silicon atoms with methanol ( 4 ) has been studied in an argon matrix at 10 K. In the initial step a triplet n‐adduct T‐5 between a silicon atom and 4 is formed. It cannot be detected directly as long as a low concentration of 4 is used. But T‐5 must be generated since upon simultaneous irradiation during cocondensation methylsilanone ( 15 ) is found. Without irradiation T‐5 undergoes immediately O,H insertion and methoxysilylene ( S‐7‐c ) is isolated, which establishes a photoequilibrium between the s,trans ( S‐7‐t ) and s,cis form ( S‐7‐c ). If a high concentration of 4 is applied the silylenes exist as complexes S‐17 . The next step needs photochemical activation. Products are dimethoxysilane ( 3 ) and (hydroxy)(methoxy)methylsilane ( 19 ). The picture becomes even more complicated when deuteromethanol ( [D]4 ) is treated with silicon atoms. In this case the primarily formed n‐adduct ( [D]T‐5 ) is stable under matrix conditions. As long as a low concentration is applied, the subsequent step has to be induced by long wavelength irradiation and leads – different from the undeuterated case – to O,CH₃ insertion, giving (hydroxy)methylsilylenes ( [D]S‐11‐c ) and ( [D]S‐11‐t ). If a high concentration is used O,D insertion is preferred instead and even without irradiation the first observable products are methanol‐solvated methoxysilylenes ( [D₂]S‐17‐c ) and ( [D₂]S‐17‐t ). Subsequent irradiation of complexes [D₂]S‐17 gives in accordance with the protonated series a mixture of [D₂]3 and [D₂]19 . Our goal, to find a way to dimethylsilanediol ( [D₂]2 ), was finally reached by preparing silylenes [D]S‐11 in a diluted matrix, its specific solvation with [D]4 and final irradiation of complexes [D₂]S‐18 . The structural elucidation of all new species is based on the comparison of the experimental observations with density functional theory calculations. Upon cocondensation of silicon atoms with pure methanol at 77 K dimethoxysilane ( 3 ) and 1,1,2‐trimethoxydisilane ( 25 ) are produced. The also present methoxysilanes 22‐24 have to be regarded as secondary products of 3 .     

Isolation of Structurally Heterogeneous TCR-CD3 Extracellular Vesicle Subpopulations Using Caliper Strategy

Cells in different states can release diverse types of extracellular vesicles (EVs) that participate in intracellular communication or pathological processes. The identification and isolation of EV subpopulations are significant to explore their physiological functions and clinical value. In this study, structurally heterogeneous T-cell receptor (TCR)-CD3 EVs were proposed and verified for the first time using a caliper strategy. Two CD3-targeting aptamers were designed in the shape of a caliper with an optimized probe distance and were assembled on gold nanoparticles (Au-Caliper) to distinguish TCR-CD3 monomeric and dimeric EVs (m/dCD3 EVs) in skin-transplanted mouse plasma. Phenotyping and sequencing analysis revealed clear heterogeneity in the isolated m/dCD3 EVs, providing the potential for mCD3 EVs as a candidate biomarker of acute cellular rejection (ACR) and holding great prospects for distinguishing EV subpopulations based on protein oligomerization states.     

Heavy-Atom Tunneling in Bicyclo[4.1.0]hepta-2,4,6-trienes

Heavy-atom tunneling limits the lifetime and observability of bicyclo[4.1.0]hepta-2,4,6-triene, a key intermediate in the rearrangement of phenylcarbene. Bicyclo[4.1.0]hepta-2,4,6-triene had been proposed as the primary intermediate of the rearrangement of phenylcarbene, but despite many efforts evaded its characterization even in cryogenic matrices. By introducing fluorine substituents into the ortho-positions of the phenyl ring of phenylcarbene, the highly strained cyclopropene 1,5-difluorobicyclo[4.1.0]hepta-2,4,6-triene becomes stable enough to be characterized in argon matrices. However, even at 3 K this cyclopropene is only metastable and rearranges via heavy-atom tunneling to the corresponding cycloheptatetraene. Calculations suggest that fluorination is necessary to slow down the tunneling rearrangement of the bicycloheptatriene. The parent bicycloheptatriene rapidly rearranges via heavy-atom tunneling and therefore cannot be detected under matrix isolation conditions.