2006 Volume 17 Issue 5

Ceric(Ⅳ)-mediated Oxidative Addition of 1, 3-Dicarbonyl Compounds to MCPs: A Facile Access to Dihydrofuran Derivatives Incorporating Cyclopropyl Groups
Wan Li CHEN , Lu Ling WU , Xian HUANG
2006, 17(5): 569-570
[Abstract](200) [FullText HTML] [PDF 55KB](0)
Abstract:
Alkylidenecyclopropanes undergo ceric(Ⅳ) ammonium nitrate (CAN)-mediated addition reaction with 1, 3-dicarbonyl compounds leading to dihydrofuran derivatives incorporating cyclopropyl groups in moderate yields.
Synthesis and Antitumor Activities of 26-O-tert-Butyldimethylsiliyl Protodisogenyl β-D-Glucopyranoside
Liang ZHOU , Shu Jie HOU , Peng XU , De Quan YU , Ping Sheng LEI , Chuan Chun ZOU
2006, 17(5): 571-574
[Abstract](221) [FullText HTML] [PDF 88KB](0)
Abstract:
New saponin 26-O-tert-butyldimethylsiliyl protodiosgenyl β-D-glucopyranoside 1 was synthesized and its cytotoxicity activity in vitro was evaluated by MTT. It showed potent antitumor activity to human cancer cells. E ring and C22-OH play important roles in the antitumor activity of 1. A method to selective removal of acetyl group in the presence of benzoyl group was reported.
Synthesis of Coumarin-functionalized Calix[4]arene and Selective Recognition for L-Tryptophan
Jian Quan LU , Li ZHANG , Ting Quan SUN , Gui Xiang WANG , Ling Yan WU
2006, 17(5): 575-577
[Abstract](208) [FullText HTML] [PDF 153KB](0)
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5, 11, 17, 23-Tetra-tert-butyl-25, 27-bis(7'-methoxycoumarin-3'-methyloxy)-26, 28-dihydroxycalix[4]arene was synthesized and characterized. The derivative could recognize L-tryptophan with a 1:1 complexing ratio and an apparent equilibrium constant of 111 L mol-1 in DMF-acetonitrile as solvent by UV-visible and fluorescent spectrophotometry.
Ionic Liquid [bmim][BF4] as a Green Medium for Passerini Reaction
Xin Ying ZHANG , Yan Zhen LI , Xue Sen FAN , Gui Rong QU , Jian Ji WANG , Xue Yuan HU
2006, 17(5): 578-580
[Abstract](280) [FullText HTML] [PDF 210KB](3)
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The Passerini three-component reaction of carboxylic acid, aromatic aldehyde and isocyanide was carried out smoothly and efficiently in ionic liquid [bmim]BF4. Through this reaction, a series of α-acyloxycarboxamides were obtained in high yields. Advantages of this procedure include a green nature, high efficiency and operational simplicity.
Synthesis of a New Polysiloxane Modified Polyurethane
Wei Feng JIANG , Shi Gui ZHAO , Yun Xia QI
2006, 17(5): 581-583
[Abstract](228) [FullText HTML] [PDF 64KB](0)
Abstract:
In this paper, a new polymer of polysiloxane modified polyurethane was synthesized by using H-containing silicone oil, toluene diisocyanate(TDI), 1, 4-butanediol and unsaturated polyether.
Synthesis of Optically Active trans-2-Aminocyclopropane-carboxylic Esters
Jiang Chun ZHONG , Shang Zhong LIU , Qing Hua BIAN , Ming Ming YIN , Min WANG
2006, 17(5): 584-586
[Abstract](209) [FullText HTML] [PDF 167KB](0)
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Two new optically active trans-2-aminocyclopropanecarboxylic esters (β-ACCs) of optical purity 91%-96% were concisely synthesized via ozonization, oxidation, Curtius rearrangement from commercial available optically active trans-chrysanthemate in total yield 36%.
Synthesis of Tritium and Deuterium Labelled Agmatine
Hong Xia HE , Zhi Bing ZHENG , Lan Fu CHEN , Zhan Bin ZHANG , Chun HU , Song LI
2006, 17(5): 587-590
[Abstract](194) [FullText HTML] [PDF 124KB](1)
Abstract:
An efficient procedure for the synthesis of agmatine labelled with tritium and deuterium is reported. The final tritiated product 4 was obtained with a specific activity of 40 Ci/mmol and a radiochemical purity of 95%.
Studies on the Neodymium-induced Pinacol Coupling of Aromatic Aldehydes and Ketones in Aqueous Media
Yan Jiang BIAN , Hai Long WANG , Bo WU , Ji Tai LI
2006, 17(5): 591-594
[Abstract](186) [FullText HTML] [PDF 146KB](0)
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Pinacol coupling reactions of aromatic aldehydes and ketones were carried out using Nd-36% HOAc-CH2Cl2 system with stirring at r. t. for 4 h (in 14-70% yield). The reactions in the same system gave pinacols in 10-93% yield under ultrasound irradiation at r.t.for 2 h.
Synthesis of α-Arylated Esters from Aryl Halides
Wei DENG , Ye Feng WANG , Lei LIU , Qing Xiang GUO
2006, 17(5): 595-598
[Abstract](245) [FullText HTML] [PDF 91KB](8)
Abstract:
An operationally simple and inexpensive catalyst system was developed for the cross coupling of aryl iodides and bromides with ethyl acetoacetate by using CuI as catalyst and Nmethyl glycine as ligand. The reaction represents a novel Cu-catalyzed C-C cross coupling reaction. This procedure is applicable to the preparation of pharmaceutically important α-arylalkanoic acids.
Synthesis and in Vitro Cytotoxicity of a Novel Conjugate of Polyamide and Phospholipid
Yi LIU , Yu Lin DENG , Rong ZHENG , Pei Long ZHANG , Hui ZHAI , Ke Zhong LIU , Chang Jin ZHU
2006, 17(5): 599-602
[Abstract](203) [FullText HTML] [PDF 168KB](1)
Abstract:
In order to increase the cell penetration and decrease the cytotoxicity of the synthetic molecule, we designed and synthesized a DNA-binding ligand, which was a conjugate of polyamide and phospholipid. We examined the differences in the effect on cytotoxicity between the conjugate and the native polyamide. As expected that the in vitro cytotoxicity of the conjugate was obviously lower than that of the native polyamide either in HeLa cells or SH-SY5Y neuroblastoma cells.
Solid Phase Synthesis of 1, 4-Disubstituted 1, 2, 3-Triazole from Polystyrene-supported Selenium Resin
Wei Ming XU , Lu Ling WU , Xian HUANG
2006, 17(5): 603-605
[Abstract](191) [FullText HTML] [PDF 116KB](0)
Abstract:
We report here a solid-phase synthesis of 1, 4-disubstituted 1, 2, 3-triazole using polystyrene-supported selenium resin. The resin used here not only works as a simple linker, but also assists the crucial α-alkylation reaction and selenoxide syn-elimination, which ensures the purity of the products.
Synthesis and Unexpected Ring-opening Reaction of a New TADDOL Analogue with Chiral Cyclopropane Ring as Backbone
Jun LIU , Qing Hua BIAN , Ming An WANG , Hong Chao GUO , Min WANG
2006, 17(5): 606-608
[Abstract](182) [FullText HTML] [PDF 163KB](0)
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Synthesis and ring-opening reaction of TADDOL analogue with cyclopropane as chiral backbone were described. A plausible ring-opening and carbonium ion rearrangement mechanism have been proposed.
Synthesis and Biological Evaluation of Novel 1, 5-Diarylpyrazole-3-carboxamide Compounds as Inhibitors of ALK5
Xian Ping DAI , Xing Zhou LI , Zhi Bing ZHENG , Song LI
2006, 17(5): 609-612
[Abstract](194) [FullText HTML] [PDF 156KB](3)
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Ten new 1, 5-diarylpyrazole-3-carboxamide compounds were synthesized and their structures were identified by 1H-NMR and FAB-MS. The primary biological tests showed that compound 4j exhibited some ALK5 inhibitory activity at concentration of 1μmol/L.
A Study on Side Reactions of Hydroxyethylation of 3-Nitro-4-chlorobenzenesulfinic Acid with Ethylene Oxide
Zhen Tang DONG , Zu Wang WU , Zhi Wei WANG , Yun De WANG , Yin Zhou YU
2006, 17(5): 613-616
[Abstract](192) [FullText HTML] [PDF 222KB](0)
Abstract:
The reaction of 3-nitro-4-chlorobenzenesulfinic acid and ethylene oxide to obtain 2-nitro-4-(β-hydroxyethylsulfonyl)chlorobenzene had been studied. Except hydroxyethylation on the sulfur atom of 3-nitro-4-chlorobenzenesulfinic acid to form the target product, 2-nitro-4-(β-hydroxyethylsulfonyl)chlorobenzene, there presented three kinds of side reactions: 1. Condensation and elimination of HCl to form biphenyl sulfone derivatives; 2. Addition to give bisulfonyl ethane derivative via vinyl sulfone; and 3. Hydroxylethylation on O-atom to produce hydroxylethylsulfinate due to the tautomerism of sulfinic acid.
A Novel Method for Beckmann Rearrangement of Oximes with Silica Sulfuric Acid under Mild Condition
Lin Fei XIAO , Jia Jian PENG , Chun Gu XIA
2006, 17(5): 617-620
[Abstract](192) [FullText HTML] [PDF 152KB](0)
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Silica sulfuric acid in which sulfuric acid is immobilized on the surface of silica gel via covalent bond has been proved to be green catalyst for liquid-phase Beckmann rearrangement of oximes in dried dioxane at room temperature. Excellent conversion and selectivity were acquired in the Beckmann rearrangement of cyclohexanone oxime. The catalyst system was recycled and reused.
Novel Piperazine-based Gemini and Bola Surfactants
Qing Shan ZHANG , Hui Miao ZHANG , Bing Nan GUO
2006, 17(5): 621-624
[Abstract](210) [FullText HTML] [PDF 104KB](0)
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A series of piperazine-based Gemini and Bola surfactants were synthesized. Gemini 1 and 5 have well surface activities. Their critical micelle concentrations (cmc) is 6.47×10-4 mol/L and 1.17×10-3 mol/L, respectively. Bola surfactants 2 and compound 3, possessing better water solubility, have lower surface activities. Calculation, carried out by MM2 energy minimization, showed that compound with more hydrophobic chains in a spacer of limited length is difficult to be synthesized.
Synthesis of 1, 4-Bis[3-N-propionyl-2-aryl-1, 3, 4-oxadiazoline-5-yl]phenylenes
De Jiang LI , He Qing FU
2006, 17(5): 625-627
[Abstract](180) [FullText HTML] [PDF 111KB](0)
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1, 4-Bis[3-N-propionyl-2-aryl-1, 3, 4-oxadiazoline-5-yl]phenylenes 4 were synthesized by cyclization of corresponding hydrazones 3 with propionic anhydride.
Two New Triterpenes from Astilbe chinensis
Jun Yi HU , Zhi YAO , Jie TENG , Yoshihisa TAKAISHI , Hong Quan DUAN
2006, 17(5): 628-630
[Abstract](189) [FullText HTML] [PDF 146KB](1)
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Two new triterpenoids, 3β, 6β, 24-trihydroxyolean-12-en-27-oic acid and 3β-acetoxy-6β-hydroxyurs-12-en-27-oic acid, as well as three known triterpenoids were isolated from the rhizomes of Astilbe chinensis. Their structures were elucidated by spectroscopic methods.These compounds showed Anti-cancer activities.
Two New Isosteroid Alkaloids from Fritillaria monatha Migo(Ⅲ)
Hong Ning LIU , Fei LI , Yong Ming LUO , Wei Feng ZHU
2006, 17(5): 631-634
[Abstract](182) [FullText HTML] [PDF 160KB](0)
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Two new isosteroid alkaloids, named pengbeimine A and pengbeimine C, were isolated from the fresh bulbs of Fritillaria monatha Migo. Their structures were determined by spectral methods, and were proved by X-ray diffraction as well.
Synthesis of a New Asymmetrical Ether Diamine with Aromatic Structure and Related Polyimide
Yu SHAO , Yan Feng LI , Xiao Long WANG , Shu Jiang ZHANG , Xin ZHAO , Tao MA
2006, 17(5): 635-636
[Abstract](181) [FullText HTML] [PDF 48KB](0)
Abstract:
A new aromatic asymmetrical ether diamine, 1, 4-bis(3', 4"-diaminophenoxy)benzene 3 was synthesized in three steps, using hydroquinone as starting material. A new aromatic polyimide containing asymmetrical diaryl ether segments was prepared from the resulting diamine with 4, 4'-oxydiphthalic anhydride (ODPA) via a conventional two-step thermal or chemical imidization method. The resulting polyimide exhibits high thermal resistance, excellent solubility, film-forming capability, high mechanical strength and modulus.
Template Polymerization Based on Stober Method: an Improved Method for Fabrication of Hollow Polysiloxane Spheres
Hui Gang WANG , Ping CHEN , Xiao Ming ZHENG
2006, 17(5): 637-640
[Abstract](205) [FullText HTML] [PDF 190KB](0)
Abstract:
A modified Stober method has been developed which permits the controlled growth of spherical hollow spheres with diameters between 197 and 208 nanometers by consecutively cocondensed methyltrimethoxysilane and dimethyldimethoxysilane monomers onto microemulsion of polydimethylsiloxane and subsequently removing the templated polydimethylsiloxane by exposure to solvents. Ammonia was used as a morphological catalyst. The morphology of the polymer spheres was demonstrated by transmission electron micrographs (TEM) and atomic force microscopy (AFM).
Molecularly Imprinted Polymers with Bi-functional Monomers of Polymerizable Cyclodextrin Derivatives and 2-(Diethylamino)-ethyl Methacrylate for Recognition of Norfloxacin in Aqueous Media
Zhi Feng XU , Lan LIU , Qin Ying DENG
2006, 17(5): 641-644
[Abstract](182) [FullText HTML] [PDF 183KB](0)
Abstract:
molecularly imprinted polymer was synthesized using 2-(diethylamino)ethylmethacry-late(DEM) and bismethacryloyl-β-cyclodextrin(BMA-β-CD) as bi-functional monomers and norfloxacin(NOF) as a template. The results of equilibrium binding experiments indicated that the polymer has affinity and specificity for NOF in aqueous media, and that its selective recognition ability for the template was higher than that of the imprinted polymers synthesized with a single functional monomer (BMA-β-CD or DEM).
Synthesis and Properties of Lactic Acid-based Cross-linked Poly(ester-amide)
Yue Ying HE , Cong Ming XIAO
2006, 17(5): 645-648
[Abstract](187) [FullText HTML] [PDF 82KB](0)
Abstract:
A novel lactic acid-based cross-linked poly(ester-amide) (LCPEA) was synthesized. The gel fraction of the LCPEA could be modulated by the reaction conditions and it affected the mechanical and thermal properties of the LCPEA. The tensile strength, elastic modulus and bend strength of the LCPEA of 65% gel fraction were 4.65, 136.55 and 39.63 MPa, respectively. The thermal decomposition temperature (50 wt%) of the LCPEA was around 410℃.
Preparation and Chiral Selectivity of BSA-Modified Ceramic Membrane
Cai Lian SU , Rong Ji DAI , Bin TONG , Yu Lin DENG
2006, 17(5): 649-652
[Abstract](188) [FullText HTML] [PDF 199KB](0)
Abstract:
An affinity-transport system, containing porous ceramic membranes bound with bovine serum albumin (BSA) was used for chiral separation of racemic tryptophan. The preparation of BSA modified ceramic membrane included three steps. Firstly, the membrane was modified with amino group using silanization with an amino silane. Secondly, the amino group modified membrane was bound with aldehyde group using gluteraldehyde. Finally, BSA was covalently bound on the surface of the ceramic membrane. Efficient separation of racemic tryptophan was carried out by performing permeation cell experiments, with BSA modified, porous ceramic membranes.
Characteristics of Titanocene Catalyst Supported on Palygorskite for Ethylene Polymerization
Xiao Wei YAN , Jing Dai WANG , Yi Bing SHAN , Yong Rong YANG
2006, 17(5): 653-656
[Abstract](196) [FullText HTML] [PDF 163KB](0)
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A series of heterogeneous catalysts with Cp2TiCl2 supported on palygorskite were prepared and evaluated by ethylene slurry polymerizations. The so-called direct supported catalyst, for which the pretreatment of palygorskite with MAO or Al(i-Bu)3 was not necessary, gave the highest activity among these supported catalysts and could be more robust than homogeneous Cp2TiCl2. With the direct supported catalyst, no significant activity loss was observed under low Al/Ti molar ratios (Al/Ti=300) and the decay of polymerization rate was slower when compared to the other supported catalysts. It was found that the surface Lewis acidity of palygorskite after thermal treatment played an important role in activation of metallocene compound and resulted in high catalyst activity.
Electrochemical Determination of Epinephrine with a Pyrolytic Graphite Electrode in the Presence of Ascorbic Acid and Dopamine
Xiu Hui LIU , Yan ZHANG , Go Fang ZUO , Xiao Quan LU
2006, 17(5): 657-660
[Abstract](170) [FullText HTML] [PDF 139KB](0)
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A method for determination of epinephrine(EP) in the presence of ascorbic acid (AA)and dopamine (DA) with bare pyrolytic graphite electrodes has been described for the first time.In pH 7.0 phosphate buffer solution, the linear relationship was observed between the reduction peak current of EP and its concentration over the range from 1×10-4 to 5×10-7 mol/L, the related coefficient is 0.9992(N=8).
The Study on the Self-assembled Monolayer (SAMs) of Porphyrin with Different Chain Length by Scanning Electrochemical Microscopy (SECM)
Li Min ZHANG , Rui Xue ZUO , Xiu Hui LIU , Xiao Quan LU
2006, 17(5): 661-664
[Abstract](172) [FullText HTML] [PDF 248KB](0)
Abstract:
The thiol-porphyrins were prepared to investigate the effect of spacer length on the gold electrode. These measurements showed that as the length of the spacers increases, the SAMs tend to form highly ordered structures on the gold electrodes. In addition, the structures of the monoalyers vary depending on the even and odd number of the methylene spacers (n).
Study on the Interferation of the Concentration of Free Calcium in Peripheral Human Lymphocyte by Low Dose Penicillin, Using Fura-2 as Fluorescent Probe
Hai Yan WANG , Dan Dan WANG , Chun Gui ZHAO , Ye Hong ZHOU , Shao Min SHUANG , Chuan DONG
2006, 17(5): 665-666
[Abstract](160) [FullText HTML] [PDF 125KB](0)
Abstract:
The effect of penicillin on the human peripheral lymphocytes was studied by steady fluorescent technique and ratiometric fluorescence dye, Fura-2. The change of the free calcium concentration in cytosol was examined under different conditions. A characterization of Fura-2-Ca interaction in an isotonic saline solution showed that Ca2+ formed a 1:1 Fura-2-Ca complex with the apparent dissociation constant 1.81×10-7 mol/L. The mechanism, by which penicillin induced the decrease of [Ca2+]i, was discussed in detail. The low dose of penicillin might modify the lymphocytes' immunology response by interfering the increase in the intracellular free calcium concentration.
A Study of Estimating the Safe Storage Life, Self-accelerating Decomposition Temperature and Critical Temperature of Thermal Explosion of Double-base Propellant Using Isothermal and Non-isothermal Decomposition Behaviours
Feng Qi ZHAO , Hong Xu GAO , Rong Zu HU , Gui E LU , Jin Yong JIANG
2006, 17(5): 667-670
[Abstract](172) [FullText HTML] [PDF 226KB](0)
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A method of estimating the safe storage life (τ), self-accelerating decomposition temperature (TSADT) and critical temperature of thermal explosion (Tb) of double-base propellant using isothermal and non-isothermal decomposition behaviours is presented. For double-base propellant composed of 56±1wt% of nitrocellulose (NC), 27±0.5wt% of nitroglycerine (NG), 8.15±0.15wt% of dinitrotoluene (DNT), 2.5±0.1wt% of methyl centralite, 5.0±0.15wt% of catalyst and 1.0±0.1wt% of other, the values of τ of 49.4 years at 40℃, of TSADT of 151.35℃ and of Tb of 163.01℃ were obtained.
Aggregation-dependence of Optical Properties and Fluorescence Quenching of a Water-soluble Poly(phenylene ethynylene)
Ming Hui YU , Hai Yang GAN , Fang HE , Yan Li TANG , Da Gui ZHENG , Shu WANG , Yu Liang LI
2006, 17(5): 671-674
[Abstract](153) [FullText HTML] [PDF 238KB](0)
Abstract:
The solvent and surfactant-dependent aggregation behaviors of the anionic poly(phenylene ethynylene) were studied and used to tune optical properties and fluorescence quenching efficiency.
Exploring Feasibility for Application of Luminescent CdTe Quantum Dots Prepared in Aqueous Phase to Live Cell Imaging
Ji Fang WENG , Xing Tao SONG , Liang LI , Hui Feng QIAN , Ke Ying CHEN , Xue Ming XU , Cheng Xi CAO , Ji Cun REN
2006, 17(5): 675-678
[Abstract](167) [FullText HTML] [PDF 167KB](0)
Abstract:
This paper explored the feasibility for the application of luminescent CdTe quantum dots prepared in aqueous phase to live cell imaging. The highly luminescent CdTe quantum dots (QDs)were first prepared in aqueous phase, and then were covalently coupled to a plant lectin (UEA-1), as a fluorescent probe. After incubating with of human umbilical vein endothelial cells (HUVECs), the QD probe with UEA-1 was able to specifically bind the corresponding cell receptor. The good cell images were obtained in live cells using laser confocal scanning microscopy. We predict that QDs prepared in water phase will probably become an attractive alternative probe in cellular imaging and bio-labeling.
Determination of Chlorine in Human Urine by Detecting Backscattering Signals with a New Optical Assembly
Ke Jun TAN , Yuan Fang LI , Cheng Zhi HUANG , Xue Lian LIU
2006, 17(5): 679-682
[Abstract](174) [FullText HTML] [PDF 159KB](0)
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Detection of backscattering signals (BSS) generally suffers from the interference of reflected light, and it is hard to apply these signals for analytical purpose. Herein we provided an optical assembly, which effectively eliminated the interference of reflected light so that the scattering signals of analyte could be measured distinctly. With this assembly, chlorine in human urine could be detected with the limit of detection (LOD) of 2.0 ng/mL by measuring the enhanced BSS signals produced between the interactions of chlorine with silver nitrate.
Electrocatalytic Oxidation of NADH Based on Self-assembled Colloidal Gold and Nafion Matrixes and Co Complex Mediator
Na WANG , Ruo YUAN , Ya Qin CHAI , Dian Ping TANG , Qiang ZHU , Xue Lian LI
2006, 17(5): 683-686
[Abstract](175) [FullText HTML] [PDF 92KB](0)
Abstract:
A novel approach based on self-assembled colloidal gold and Nafion matrixes and Co complex mediator to construct Co(bpy)33+/nano-Au/Co(bpy)33+/nafion/GC electrode, on which formed stable redox-active films. This electrode can decrease the overpotential about 330 mV for the oxidation of NADH with high stability, wide linear range and low detection limit.
The Effect of Potassium Citrate on Simultaneous Growth of Calcium Oxalate Mono-, Di-, and Trihydrate in Synthetic Urine
Yi Ming LIU , Feng Xin WANG , Sui Ping DENG , Jian Ming OUYANG
2006, 17(5): 687-690
[Abstract](177) [FullText HTML] [PDF 115KB](0)
Abstract:
The inducing effect of potassium citrate (K3cit) on simultaneous growth of calcium oxalate mono-(COM), di-(COD), and trihydrate (COT) crystals in synthetic urine was observed with double diffusion gelatinous technique. K3cit can induce the formation of COD and COT, inhibit the aggregation and decrease the surface area of COM crystals. It supported the clinical use of K3cit and may provide important clues to this disease in cure and in search for new drugs.
Interaction of Chelerythrine Choloride in Acid Buffer with Calf-thymus DNA
Yan Jing SU , Xiong Hui WEI
2006, 17(5): 691-694
[Abstract](174) [FullText HTML] [PDF 228KB](0)
Abstract:
The binding of chelerythrine (CHE) iminium to calf-thymus (CT) DNA is characterized by hypochromism and bathochromism in the absorption band, enhancement of fluorescence intensity, increase in fluorescence polarization, and the perturbation of the CD spectra of DNA.These changes are characteristic of intercalation. Scatchard plots constructed from fluorescence titration data gave a binding constant of 5.77×105 and a binding site size of 3, 4 base pairs at 25℃.The intercalative interaction is exothermic with a Van't Hoff enthalpy of -33.7 kJ/mol. In addition, △G=-32.9 kJ/mol, and △S=-2.9 J/mol/K. The intercalation of CHE into the DNA helix is enthalpy-driven.
Rheological and DSC Studies on the Interaction between κ-Carrageenan and Cellulose Nanocrystals (CNC)
Rui GUO , En Yong DING
2006, 17(5): 695-698
[Abstract](158) [FullText HTML] [PDF 320KB](0)
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Rheometer and differential scanning calorimetry (DSC) have been used to probe the mechanism of gelation in gels formed by mixture of κ-carrageenan and cellulose nanocrystals (CNC). The results indicated that an association occurred between CNC chains and aggregated κ-carrageenan helices.
Thermal Characterization and Decomposition Kinetics of Free Anthraquinones from Rhubarb
Li Ming ZHANG , Xia LI , Yu Jie DAI
2006, 17(5): 699-702
[Abstract](181) [FullText HTML] [PDF 219KB](2)
Abstract:
The thermal behaviour of aloe-emodin, chrysophanol and physcion and their kinetics have been investigated under non-isothermal conditions by means of differential thermal analysis (DTA) and thermogravimetry (TG). The thermal characteristics have been determined using the DTA and TG-DTG curves. The non-isothermal kinetic data were analyzed by means of the Achar method and the Madhusudanan-Krishnan-Ninan (MKN) method. The possible reaction mechanisms have been investigated by comparing the kinetic parameters. The kinetic equation for aloe-emodin, chrysophanol and physcion can be expressed as dα/dt=Aexp(-E/RT)1/3(1-α)[-In(1-α)]-2. The activation energy E (kJ mol-1) of the three free anthraquinones are 78.09, 89.54, and 107.5 and their lnA/s-1 are 22.98, 36.85 and 43.60, respectively.
The In-cell iR Compensation Using a Four-electrode System
Xiang Qin LIN , Liang Dong FENG
2006, 17(5): 703-706
[Abstract](166) [FullText HTML] [PDF 162KB](0)
Abstract:
A novel idea of in-cell iR compensation was proposed by using a four-electrode electrochemical system, which was consisted of two working electrodes, one reference electrode (RE)and one auxiliary electrode (AE). One of the two working electrodes was called the auxiliary working electrode (AWE), which was directly connected to the ground. Another working electrode was used as a regular working electrode (WE) for electrochemical testing. The reference electrode was set in a frit close to the AWE for potential sampling. The other electrodes, WE, RE and AE, were connected to a conventional potentiostat of three-electrode system for electrochemical measurements. A linear narrow electrochemical cell was designed for setting AE at one end and AWE with RE at another end, and setting WE in between AE and AWE. In this way, a positive feedback potential was generated at the working electrode from the solution resistance and the current flow in the solution. An formal iR compensation over 100%, as high as 500%, had been achieved without potential oscillation. The electrochemical cell design, the principle of the in-cell iR compensation, and the preliminary voltammetric characterization by using the redox reaction of ferrocyanide anions were reported.
A Cooperative Approach for the Extraction of Protein Motifs
Chao CHEN , Yuan Xin TIAN , Xiao Yong ZOU , Pei Xiang CAI , Jin Yuan MO
2006, 17(5): 707-710
[Abstract](167) [FullText HTML] [PDF 99KB](0)
Abstract:
By integrating the concept of cooperative approach, an extension of the fast annealing coevolutionary algorithm is presented in this paper. It outperformed the original algorithm in the domain of function optimization, especially in terms of convergence rate. It was also applied to a real optimization problem, protein motif extraction. And a satisfactory result has been obtained with the accuracy of prediction achieving 67.0%, which is in agreement with the result in the PROSITE database.
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