Monte Carlo simulations of systems of rodlike molecules with semiflexible terminal groups

The results of Monte Carlo simulations of systems of rodlike molecules with semiflexible terminal groups are compared with those of systems with terminal groups at a fixed angle τ with respect to the rigid core and with those of a system containing the rigid cores alone in the same total volume. The nematic/isotropic transition temperature decreases with increasing flexibility or with increasing τ. For semiflexible groups, the transition is coupled with a conformational change favouring more extended conformations in the nematic phase. The results of the simulations are discussed in connection with those obtained for similar models in the recent literature and with the predictions of the Maier‐Saupe and Flory‐Ronca‐Irvine theories.     

表面等离子体子共振传感器用于研究不同材质包裹的磁性纳米粒子性质

利用自行设计组装的以白色发光二极管为光源的表面等离子体子共振传感器实验装置, 检测了不同材质包裹的磁性纳米粒子连接靶向DNA与生物素化DNA探针的结合程度. 结果表明, 与聚苯乙烯磁性微球连接的靶向DNA相比, Fe3O4@SiO2核壳式纳米微球连接的靶向DNA与生物素化的DNA探针结合速率较快, 且其相对标准偏差较小.     

金蒲抑瘤片在鼻咽癌的临床应用研究

为探讨鼻咽癌患者放疗期间合并应用金蒲抑瘤片治疗对细胞免疫功能及血中微量元素硒、锌、铜的影响，经病理证实鼻咽癌患者58例，随机分为放疗服药组30例和单纯放疗组28例。两组放疗前后抽静脉血测定T细胞亚群（CD3＋，CD4＋，CD8＋，CD4＋／CD8＋），血中微量元素硒，锌，铜并与30例健康者（正常对照组）进行比较。结果表明，鼻咽癌患者血中微量元素硒，锌，铜及CD3＋，CD4＋，CD4＋／CD8＋显著低于健康人，放疗期间合并应用金蒲抑瘤片治疗后血中微量元素硒，锌，铜及CD3＋，CD4＋，CD4＋／CD8＋较服药前显著升高。提示鼻咽癌患者细胞免疫功能低下，血中微量元素硒，锌，铜显著低于健康人。金蒲抑瘤片能提高鼻咽癌患者因中微量元素硒，锌，铜含量，使低下的细胞免疫功能迅速恢复。     

乳腺癌术前灰阶超声与彩色多普勒超声联合应用对预后的预测价值

目的探究乳腺癌术前灰阶超声与彩色多普勒超声联合应用对预后的预测价值。方法选取温州医科大学附属第一医院2013年5月—2015年5月期间收治的乳腺癌患者83例,治疗前均行灰阶超声与彩色多普勒超声检查,分析患者超声检查结果、临床征象与术后随访2年期间患者预后的关系,从而分析术前灰阶超声与彩色多普勒超声联合应用对乳腺癌患者预后的预测价值。结果乳腺癌肿块边界清晰、边界不清晰、边界恶性晕的患者2年无瘤生存率依次降低,边界恶性晕与边界不清晰患者死亡率均显著高于边界清晰患者(P0.05);肿瘤≥2 cm患者2年无瘤生存率显著低于2 cm患者;淋巴结转移患者2年无瘤生存率显著低于无转移患者(P0.05);血流分级Ⅱ级患者2年无瘤生存率明显低于0级(P0.05),Ⅲ级患者2年无瘤生存率显著低于0级和Ⅰ级(P0.05)。结论乳腺癌患者术前联合应用灰阶超声与彩色多普勒超声检查可确定肿瘤边界、大小及淋巴转移等征象,其与患者无瘤生存率、死亡率等预后指标密切相关,可作为预测乳腺癌患者预后的重要方法。     

Zur reaktionvon cyclotri- und cyclotri- und cyclotetrasilazanen mit silylfluoriden

Fluorosilyl substituted cyclosilazanes are formed by treating lithium salts of hexamethylcyclotri- and octa-methylcyclotetrasilazanes with silicon tetrafluoride and organo-substituted silicon fluorides. Disubstituted compounds are obtained by the reaction of dilithium hexamethylcyclotrisilazane with silicon fluorides or by the reaction of lithium hexamethylcyclotrisilazane with silicon fluorides at higher temperature. Cyclosilazanes with bulky ligands react with butyllithium with elimination of butane as a first step and then react further with a silicon fluoride compound, with LiF-elimination, to give a mixed substituted cyclosilazane. Ring coupling through a silicon bridge is achieved by the reaction of a fluorosilyl-substituted cyclotrisilazane with lithium hexamethylcyclotrisilazane. The mass,¹H and¹⁹F NMR spectra of the compounds are reported.     

Aryl- and alkenyllithium preparations and copper-catalyzed reaction between the derived magnesium reagents and the monoacetate of 4-cyclopentene-1,3-diol

[reaction: see text] Aryl- and alkenyllithiums, prepared by halogen-lithium exchange with lithium, exchange with n-(or t-)BuLi, stannane-lithium exchange with n-BuLi, and direct lithiation with n-BuLi, were transformed into magnesium reagents with MgCl2 and subjected to CuCN-catalyzed reaction with the title monoacetate. Except for the halogen-lithium exchange with n-BuLi, the other preparations of the lithium anions were found to be compatible with the CuCN-catalyzed reaction to afford S(N)2-type products efficiently.     

N-去甲万古霉素的亲和吸附

通过交联聚丙烯酸甲酯与乙醇胺反应,形成聚(N-羟乙基丙烯酰胺)树脂,在酸催化作用下与环氧氯丙烷反应,形成含有α-羟基氯乙基的树脂.含α-羟基氯乙基的树脂与D-丙氨酸、L-丙氨酸或甘氨酸反应,分别得到含有这3种氨基酸的吸附剂.这3种吸附剂吸附N-去甲万古霉素的结果表明,含D-丙氨酸的吸附剂的吸附量最大,含甘氨酸的吸附剂的吸附量次之,而含L-丙氨酸的吸附剂不吸附N-去万古霉素.说明前两种吸附剂对N-去甲万古霉素存在亲和吸附作用.含D-丙氨酸吸附剂的最佳吸附pH值为5.8,当吸附液中的盐(NaCl)浓度增加时,吸附量降低.用0.4mol/LNa₂CO₃/CH₃CN(摩尔比7∶3,pH=9.5)作为洗脱剂可完全脱附被吸附的N-去甲万古霉素.     

Reaction features of 2,3,4-trichloro-1-butene with phosphoric and nitrogen nucleophiles

Reaction of 2,3,4-trichloro-1-butene with phosphoric and nitrogen nucleophiles was carried out. In the reaction with allyldiphenylphosphine 1,4-bis-(allyldiphenylphosphoniochlorido)-1,3-butadiene was obtained, with tributylphosphine, allyldimethylamine and trimethylamine respective 1,4-bis-onium salts with 2-chloro-2-butenylene group. Reaction with trimethylamine proceeded with formation of monoammonium salt with 3,4-dichloro-2-butenyl group. It is noteworthy that 1,4-splitting of 1,4-bis-(trimethylammoniochlorido)-2-butene at the action of sodium methoxide occurs with involvement of the less labile hydrogen atom.     

Application of electron-attachment reactions to enhance selectivity of electron-capture detector for nitroaromatic explosives

The differences in the extent of electron-attachment reactions between thermal electrons and selected classes of organic molecules with high electron affinities were investigated. The investigations showed that interactions of thermal electrons with nitroaromatic compounds lead to the formation of neutral products with very low electron affinities. By contrast, a number of other analytes with high electron affinities such as polyhalogenated organic compounds, lead to products with high electron affinities. This difference was exploited to differentiate between nitroaromatic and polychlorinated organic compounds with a tandem arrangement consisting of two electron-capture detectors connected in series with an electron-attachment reactor.     

Determination of paraquat in marijuana by reversed-phase paired-ion high performance liquid chromatography.

A sensitive and selective method is described for the quantitative determination of paraquat in marijuana. Paraquat is extracted from finely ground plant material with hydrochloric acid with sonification, and the resulting acidic solution is extracted with chloroform:isopropanol (9:1) and evaporated to dryness. The residue is reconstituted with aqueous phosphate buffer pH 7.0; the solution is passed through a C-18 SEP-PAK TM and is analyzed with high performance liquid chromatography, using a reversed-phase column and an "ion pairing" reagent in the mobile phase. The recovery of paraquat in laboratory-spiked material varied from 90-97%. Results obtained with confiscated, field-sprayed marijuana by the procedure described were in excellent agreement with those obtained with a well-established ultraviolet procedure. The calculated limit of detection with this method is 2 ng of paraquat.     

Effective 1,5-, 1,6- and 1,7-remote stereocontrol in reactions of alkoxy- and hydroxy-substituted allylstannanes with aldehydes

Alk-2-enylstannanes with 4-, 5- and 6-alkoxy- or -hydroxy-substituents are transmetallated stereoselectively with tin(iv) halides to generate allyltin trihalides which react with aldehydes to give (Z)-alk-3-enols with useful levels of 1,5-, 1,6- and 1,7-stereocontrol. Alk-2-enylstannanes with a stereogenic centre bearing a hydroxy or alkoxy group at the 4-, 5- or 6-position, react with overall (Z)-1,5-, 1,6- and 1,7-syn-stereoselectivity with respect to the hydroxy and alkoxy substituents. The analogous reactions of alkoxy- and -hydroxyalk-2-enylstannanes with a methyl bearing stereogenic centre at the 4- or 5-position react with overall (Z)-1,5- and 1,6-anti-stereoselectivity with respect to the hydroxy and methyl substituents.     

Photoaddition of ketones to imidazoles,thiazoles, isothiazoles and isoxazoles. Synthesis of their oxetanes

Imidazole itself did not undergo photoaddition reactions with ketones. However, irradiation of 1-acetyl and 1-benzoylimidazole, and 1,1-carbonyldiimidazole with benzophenone yielded oxetanes. On irradiation with carbonyl compounds, 1,2-dimethylimidazole and 1-benzylimidazole did not give oxetanes but a hydroxyaryl or hydroxyalkyl derivative. Thiazole itself did not yield any photoaddition product, but 2,4-dimethylthiazole afforded oxetanes on irradiation with benzophenone and with 3-benzoylpyridine. Irradiation of 2,4-dimethylthiazole with acetophenone led to the formation of a dimeric material. On irradiation with benzophenone, 4-methylisothiazole did not yield an oxetane but rather a hydroxyphenyl derivative. 3,5-Dimethylisoxazole on irradiation with benzophenone and with 3-benzoylpyridine gave oxetanes. Irradiation of 4,5-dimethylisoxazole yielded similarly an oxetane with benzophenone     

Comparison of electrothermal atomization diode laser Zeeman- and wavelength-modulated atomic absorption and coherent forward scattering spectrometry

Atomic absorption and coherent forward scattering spectrometry by using a near-infrared diode laser with and without Zeeman and wavelength modulation were carried out with graphite furnace electrothermal atomization. Analytical curves and limits of detection were compared. The magnetic field was modulated with 50 Hz, and the wavelength of the diode laser with 10 kHz. Coherent forward scattering was measured with crossed and slightly uncrossed polarizers. The results show that the detection limits of atomic absorption spectrometry are roughly the same as those of coherent forward scattering spectrometry with crossed polarizers. According to the theory with bright flicker noise limited laser sources the detection limits and linear ranges obtained with coherent forward scattering spectrometry with slightly uncrossed polarizers are significantly better than those obtained with crossed polarizers and with atomic absorption spectrometry. This is due to the fact that employing approaches of polarization spectroscopy reduce laser intensity fluctuations to their signal carried fractions.     

Fluorometric assay of ultramicro quantities of glucose with somogyi filtrate and hexokinase

A procedure is described for the determination of glucose in 3 μl of serum or plasma. It is based on the phosphorylation of glucose with ATP mediated by hexokinase. The TPNH generated with glucose-6-phosphate dehydrogenase is measured fluorometrically.Sensitivity is greatly improved over the corresponding procedure using UV absorption for the determination of NADPH. Bilirubin does not interfere. Interference from hemolysis is eliminated by precipitation with Zn(OH)₂ Blood taken with fluoride can be utilized. Fluoride interference is removed with the Zn(OH)₂ and with excess Mg in the substrate. Positive interference by fructose is negligible with some enzyme preparations but is appreciable with others.The results correlate well with those obtained with an ortho toluidine method, after protein precipitation with trichloroacetic acid. The method is especially useful in the Pediatric Laboratory.     

合成聚芳酯树状分子的新方法

以３，５－二羟基 苯甲酸为起始原料，经甲醇酯化保护羧基，与苯甲酰氯反应，得到３，５－二苯甲酰氧基苯甲酸甲酯用ＡｌＣｌ３．ＮａＩ去掉保护基甲基，以高收率得到３，５－二苯甲酰氧基苯甲酸。其结构均是由ＩＲ，＾１ＨＮＭＲ，ＥＡ等方法证实。     

Modification of supercapacitor electrodes with polymer metallocomplexes: Methods and results

A procedure for electrochemical modification of carbon materials with high specific surface was developed. The materials were modified with polymeric nickel complexes with Schiff bases. The prototype of a hybrid double-layer Faraday supercapacitor with a positive carbon electrode modified with a polymeric complex was studied. Modification of this type doubled the energy stored by the hybrid capacitor compared with the similar double-layer capacitor.     

DOTTADs--readily made novel metal ligands with multivariant functionality

The interaction of Hantzsch pyridinecarboxylic acids with dialkylformamides and POCl3, followed by treatment with NH4OH yields 1,8-dioxo-1,2,7,8-tetrahydro-2,7,10-triazaanthracenes (DOTTADs), which have great potential as useful ligands for Group I and II metals and some transition metals. The corresponding Hantszch esters similarly for DOTTADs or their bis-imines by way of isolable intermediates, which are then treated with an amine RNH2. DOTTAD-imines are also available from DOTTADs with amines and this reaction is also effective with 1,8-diamino-3,6-dioxaoctane to give macrocyclic analogues, as well as with chiral amines. DOTTAD-imines can be reduced with diethylsilane and Wilkinson's catalyst to the corresponding amines, which can also be formed from DOTTADs by reductive amination with amines and Na(AcO)3BH. Mono-aldols of DOTTADs are easily formed by treatment of DOTTADs with acetone.     

Interference by the Catecholic Cephalosporin BRL-41897-A with Diagnostic Clinical Chemistry Assays

The catecholic cephalosporin BRL-41897-A, was investigated for in vitro interference with commonly used clinical chemistry assays. An important finding was a negative interference with the enzymatic cholesterol assay that incorporates the Trinder reaction, in which hydrogen peroxide produced by an oxidase drives the oxidative coupling of a phenol with 4-aminophenazone to produce a colored quinoneimine. The suspected interference by BRL-41897-A with the Trinder reaction was investigated using a uricase driven system in which the phenol reagent was substituted or combined with BRL-41897-A. The results indicate that BRL-41897-A competes with the phenol component to react preferentially with 4-aminophenazone to produce a quinoneimine of low absorptivity. Further investigations conducted with similar enzymatic assays for creatinine, cholesterol, triglycerides, and uric acid showed the interference varied substantially with analyte and was dependent on analyte concentration.     

A coupled reagent of o-phthalaldehyde and sulfanilic acid for protein detection based on the measurements of light scattering signals with a common spectrofluorometer

A rapid and sensitive method for the determination of proteins is proposed with a coupled reagent of o-phthalaldehyde and sulfanilic acid by measuring the light scattering (LS) signals with a common spectrofluorometer. Mechanism investigations showed that o-phthalaldehyde couples at first with sulfanilic acid with fast speed and forms a new synthesized Schiff base dye, which then interacts with protein rapidly on acidic condition, resulting in greatly enhanced LS signals with the maximum peak located at 344 nm. Based on the linear relationship between enhanced LS intensities and concentrations of proteins, a novel assay of HSA and BSA is established in the linear range of 0.1-25.0 microg ml(-1) with the limits of detection (3sigma) being 13 ng ml(-1) depending on the concentration of the reagent. Results for sample detections of our method were consistent with the documented spectrophotometric method with CBB G250 assay.     

Electrochemical Characterization of the Interaction of Multiwalled Carbon Nanotubes with Doxorubicin

It has been suggested that multiwalled carbon nanotubes (MWCNTs) interacting with pharmaceutics may be introduced into the body as nanocarriers. To deliver the anticancer drugs, covalent or noncovalent functionalization of MWCNTs is required. In this study, the influence of oxidation on MWCNTs in the interaction with chemotherapeutic drug, doxorubicin, was characterized. The binding of doxorubicin with MWCNTs decreased rapidly with the increasing oxidation period with sulfuric acid. However, with nitric acid, the interaction increased initially and slowly decreased with time. The best results were obtained for sulfuric and nitric acid following 1 and 3?h of oxidation, respectively. The results show that sulfuric acid provided more favorable interaction for MWCNTs with doxorubicin than nitric acid.