2007 Volume 18 Issue 11

Sulfanilic acid catalyzed solvent-free synthesis of 1,5-benzodiazepine derivatives
Jaiprakash N. Sangshetti , Nagnnath D. Kokare , Devanand B. Shinde
2007, 18(11): 1305-1308  doi: 10.1016/j.cclet.2007.09.022
[Abstract](54) [FullText HTML] [PDF 254KB](0)
Abstract:
Sulfanilic acid has been found to be an efficient catalyst for the synthesis of 1, 5-benzodiazepines from o-phenylenediamine and ketones. This method is simple, effective and environmentally friendly and gives better yields.
Oxalic acid catalyzed solvent-free one pot synthesis of coumarins
Nagnnath D. Kokare , Jaiprkash N. Sangshetti , Devanand B. Shinde
2007, 18(11): 1309-1312  doi: 10.1016/j.cclet.2007.09.008
[Abstract](65) [FullText HTML] [PDF 255KB](1)
Abstract:
Oxalic acid was found to be an efficient catalyst for Pechmann condensation, which includes the reaction between phenols and β-keto esters leading to formation of coumarin derivatives. The advantages of present methods are the use of cheap and easy available catalyst, solvent-free reaction conditions, better yields and shorter reaction time.
Facile synthesis of 9-(N-amino-4-fluoromethyl-3-pyrrolidinyl)-2-fluoro-6-aminopurine from trans-4-hydroxy-L-proline
Ye Qing Li , Ming Lu , Chun Xu Lu , Sai Jian Zhu , Qi Fa Liu
2007, 18(11): 1313-1315  doi: 10.1016/j.cclet.2007.09.020
[Abstract](66) [FullText HTML] [PDF 242KB](2)
Abstract:
A novel and simple procedure for synthesis of azanucleoside by Mitsunobu reaction between N-(p-nitrobenzyloxycarbonyl)-trans-4-hydroxy-D-proline methyl ester obtained from trans-4-hydroxy-L-proline after six-step reaction and 2-fluoro-6-azidopurine is described, and azanucleoside is fluorinated by new fluridizer 2, 2-difluoro-1, 3-dimethylimidazolidine (DFI). All reactions could be carried out under mild condition.
Two new compounds derived from bufalin
Jun Zhao , Shu Hong Guan , Xiao Bin Chen , Wei Wang , Min Ye , De An Guo
2007, 18(11): 1316-1318  doi: 10.1016/j.cclet.2007.09.023
[Abstract](50) [FullText HTML] [PDF 244KB](0)
Abstract:
The biotransformation of bufalin by cell suspension cultures of Platycodon grandiflorus was investigated and two new biotransformed products were obtained, which was 3-epi-telocinobufagin and 3-epi-bufalin-3-O-β-D-glucoside.
The synthesis and spectroscopic investigation of vinylated meso-tetraphenylporphyrin
Jin Qiang Xue , Ya Qing Feng , Lei Wang , Ling Hui Wu
2007, 18(11): 1319-1322  doi: 10.1016/j.cclet.2007.09.032
[Abstract](51) [FullText HTML] [PDF 289KB](0)
Abstract:
A series of new vinylated 5, 10, 15, 20-tetraphenylporphyrins have been synthesized and characterized by 1H NMR, MS, UV-vis and fluorescence studies. Following selective excitation of the porphyrin compounds with UV light, the energy is transferred to the porphyrin core and reemitted as red light. In comparison to tetraphenylporphyrin (TPP), the luminescence properties are markedly improved.
Synthesis of mangiferin derivates and study their potent PTP1B inhibitory activity
Hong Gang Hu , Ming Juan Wang , Qing Jie Zhao , Shi Chong Yu , Chao Mei Liu , Qiu Ye Wu
2007, 18(11): 1323-1326  doi: 10.1016/j.cclet.2007.09.011
[Abstract](58) [FullText HTML] [PDF 255KB](0)
Abstract:
Protein tyrosine phosphatase 1B (PTP1B) has received considerable attention from the drug industry as a potential treatment fordiabetes mellitus. Mangiferin has been reported to possess significant antidiabetic activity. Based on the previous study, eight new mangiferin derivates were synthesized and evaluated for their PTP1B inhibitory activity. Some of them displayed good inhibitory activity on PTP1B.
Microwave-assisted synthesis of new pyrimido[4',5':4,5]thiazolo[3,2-a]benzimidazol-4(3H)-one derivatives in solvent-free condition
A. Davoodnia , M. Roshani , E. Saleh Nadim , M. Bakavoli , N. Tavakoli Hoseini
2007, 18(11): 1327-1330  doi: 10.1016/j.cclet.2007.09.004
[Abstract](52) [FullText HTML] [PDF 264KB](0)
Abstract:
Microwave-assisted synthesis of new 2-arylpyrimido[4', 5':4, 5]thiazolo[3, 2-a]benzimidazol-4 (3H)-ones from 3-aminothiazolo[3, 2-a]benzimidazol-2-carboxamide and aroyl halides in solvent-free condition is described. In comparison with classical conditions the reactions are faster and the yields are higher under microwave irradiation.
Synthesis and anticancer activities of porphyrin induced anticancer drugs
Dong Hong Li , Jun Lin Diao , Ke Gui Yu , Cheng He Zhou
2007, 18(11): 1331-1334  doi: 10.1016/j.cclet.2007.09.012
[Abstract](53) [FullText HTML] [PDF 258KB](0)
Abstract:
In view of the property of porphyrin's accumulation selectively in tumor, the ftorafur was modified by binding a porphyrin block to improve its tumor targeting and reduce its side effects. These novel porphyrin derivatives and metal compounds were synthesized under mild conditions with satisfactory yield, and the constructions of all these new compounds were characterized by UV, IR, MS, 1H NMR spectra and elementary analysis. Their anticancer activities were evaluated by MTT assay; the results indicated that the anticancer activities of compounds 4a-c were twice as high as that of ftorafur.
Synthesis and antitumor activity of heterocyclic acid ester derivatives of 20S-camptothecins
Di Zao Li , Yan Li , Xiao Guang Chen , Chen Gen Zhu , Jing Yang , Hong Yan Liu , Xian Dao Pan
2007, 18(11): 1335-1338  doi: 10.1016/j.cclet.2007.09.014
[Abstract](55) [FullText HTML] [PDF 287KB](0)
Abstract:
A series of heterocyclic acid esters of camptothecins as new compounds had been synthesized by acylation method, their in vitro and in vivo antitumor activities were evaluated. The cytotoxic results showed that 6 possessed the best efficacy on six human cancer cell lines in the six classes of CPTs' derivatives. In vivo testing results indicated that 9 had better antitumor activity against mouse liver carcinoma H22 than topotecan.
A new method for inversion of hydroxyl group of carbocyclic nucleosides
Xiao Zhen Liu , Fei Wang , Dong Dong Luo , Xing Guo , Guang Qing Lei
2007, 18(11): 1339-1341  doi: 10.1016/j.cclet.2007.09.002
[Abstract](51) [FullText HTML] [PDF 278KB](0)
Abstract:
The hydroxyl group of carbocyclic nucleosides was inversed when the compounds were treated with Me3SiCl, KCN and a catalytic amount of NaI in DMF/CH3CN.
Synthesis and characterization of a novel main chain oxadiazole-based copolymer for n-type solar cell material
Xian Rong Cai , Hao Chen , Tao Zhang , Xing Xu , Ying Li , Qing Jiang
2007, 18(11): 1342-1346  doi: 10.1016/j.cclet.2007.09.035
[Abstract](52) [FullText HTML] [PDF 423KB](0)
Abstract:
A novel oxadiazole-based copolymer has been successfully synthesized through the palladium-catalyzed cross-coupling polycondensation method. The copolymer P is soluble in common organic solvents. Its structure has characterized by 1H NMR, 13C NMR, gel permeation chromatagraphy (GPC), UV-vis absorbance (Abs) and photoluniminescence (PL) spectroscopy, and cyclic voltammetry (CV). Investigation of its optical properties revealed that it is yellow emitting material, and the electrochemical analysis showed that P was well suited poly (2, 5-dioctyloxy-p-phenylenevinylene) (PDOCPV) for photovoltaic devices, so the copolymer P is able to act as an electron acceptor in combination with PDOCPVas the electron donor to quench photoluminescence of the copolymer in the blend, indicative of the efficient photoinduced electron transfer from the PDOCPV to the P.
The synthesis and cytotoxic activity of novel organogermanium sesquioxides with anthraquinone or naphthalene moiety
Guo Qiang Shangguan , Lun Liang Huang , Xiao Gang Qu
2007, 18(11): 1347-1350  doi: 10.1016/j.cclet.2007.09.029
[Abstract](58) [FullText HTML] [PDF 257KB](0)
Abstract:
Four novel organogermanium sesquioxides with anthraquinone or naphthalene moiety were synthesized. The structures were characterized by IR, NMR and elemental analysis, and their cytotoxicities were evaluated against human chronic myeloid leukemia K562 cell lines. The cytotoxicity could be improved by the introduction of planar aromatic chromophore moiety to the parent compound, Ge-132.
Synthesis of new 1,3-bis (phenylethynyl) disilazanes
Xiao Wen Hu , Zhi Min Zheng , Cai Hong Xu
2007, 18(11): 1351-1352  doi: 10.1016/j.cclet.2007.09.036
[Abstract](51) [FullText HTML] [PDF 206KB](0)
Abstract:
Three new 1, 3-bis (phenylethynyl) disilazanes were synthesized from the reaction of 1, 3-dichlorodisilazanes with (phenylethynyl) lithium, and characterized by infrared (IR) spectra, nuclear magnetic resonance (NMR) and mass spectrometry (MS).
Solvent-free esterification of poly (vinyl alcohol) and maleic anhydride through mechanochemical reaction
Bo Zhao , Can Hui Lu , Mei Liang
2007, 18(11): 1353-1356  doi: 10.1016/j.cclet.2007.09.019
[Abstract](57) [FullText HTML] [PDF 269KB](0)
Abstract:
A solid-state mechanochemical processing, that is, pan-milling, was used to conduct the esterification of poly (vinyl alcohol) (PVA) with maleic anhydride (MA) through stress-induced reaction. FTIR spectrum study indicated the presence of ester linkages and olefinic double bonds in maleic anhydride cross-linked PVA. Thermal properties of the cross-linked product were characterized by DSC. The results showed its glass transition temperature was 20℃ higher than the original linear PVA and the thermal stability was also improved.
Solventless synthesis of 2-aryl-1-arylmethyl-1H-1,3-benzimidazoles catalyzed by Fe (ClO4)3 at room temperature
Hossien A. Oskooie , Majid M. Heravi , Akbar Sadnia , Farahnaz K. Behbahani , Fatemeh Jannati
2007, 18(11): 1357-1360  doi: 10.1016/j.cclet.2007.09.030
[Abstract](55) [FullText HTML] [PDF 233KB](0)
Abstract:
A series of 2-aryl-1-arylmethyl-1H-1, 3-benzimidazoles was synthesized expeditiously in good yields from o-phenylenediamines and aldehydes in the presence of Fe (ClO4)3 without solvent at room temperature.
Asymmetric synthesis of 3-butylphthalide using isomannide and isosorbide as chiral auxiliaries
Zhen Li Min , Yi Hua Zhang , Yi Sheng Lai , Si Xun Peng
2007, 18(11): 1361-1363  doi: 10.1016/j.cclet.2007.09.038
[Abstract](57) [FullText HTML] [PDF 233KB](0)
Abstract:
A new approach for asymmetric syntheses of (S) and (R)-3-n-butylphthalide (NBP) is presented. The diastereoselective addition of dibutylzinic to aromatic aldehyde 10 or 11 generated from isomannide-or isosorbide-derived chiral auxiliary afforded S-NBP or R-NBP in high optical yields.
A novel alkenoic acid ester and a new benzophenone from Ranunculus ternatus
Ying Xiong , Ke Zhong Deng , Wen Yuan Gao , Yuan Qiang Guo , Tie Jun Zhang
2007, 18(11): 1364-1366  doi: 10.1016/j.cclet.2007.09.017
[Abstract](57) [FullText HTML] [PDF 249KB](0)
Abstract:
A novel alkenoic acid ester, (E)-4-hydroxy-dodec-2-enedioic acid-12-O-methyl ester and a new benzophenone, ethyl (S)-3-[2-(3, 4-dihydroxybenzoyl)-4, 5-dihydroxyphenyl]-2-hydroxypropanoate, together with a known compound, (E)-4-hydroxy-dodec-2-enedioic acids were isolated from the roots of Ranunculus ternatus. Their structures were elucidated by spectroscopic methods.
Four new constituents from Taraxacum mongolicum
Shu Yun Shi , Qi Zhou , Hua Peng , Chang Xin Zhou , Ming Hui Hu , Qiao Feng Tao , Xiao Jiang Hao , Joachim Stöckigt , Yu Zhao
2007, 18(11): 1367-1370  doi: 10.1016/j.cclet.2007.09.005
[Abstract](57) [FullText HTML] [PDF 246KB](1)
Abstract:
Two new flavone glycosides, isoetin-7-O-β-D-glucopyranosyl-2'-O-α-L-arabinopyranoside (1) and isoetin-7-O-β-D-glucopyranosyl-2'-O-α-D-glucopyranoside (2), a new lignan, mongolicumin A (3), and a new guaianolide, mongolicumin B (4) were isolated from the aerial part of Taraxacum mongolicum. Their structures were elucidated mainly by spectral analyses.
The photoluminescence of Co-Al-layered double hydroxide
Shuai Sun , Wan Guo Hou
2007, 18(11): 1371-1373  doi: 10.1016/j.cclet.2007.09.024
[Abstract](50) [FullText HTML] [PDF 1173KB](0)
Abstract:
We report a new optical behaviour of pure Co-Al-layered double hydroxide (LDH). It was found that the Co-Al-LDH sample could emit fluorescence without any fluorescent substances intercalated. Its excitation spectrum shows a maximum peak near the wavelength 370 nm, the maximum emission peak appears at 430 nm and the photoluminescence colour of the Co-Al-LDH sample is blue. This new optical property will be expected to extend the potential applications of LDHs in optical materials field.
A novel phycocyanin-Chla/c2-protein complex isolated from chloroplasts of Chroomonas placoidea
Min Chen , Si Hui Li , Li Sun
2007, 18(11): 1374-1378  doi: 10.1016/j.cclet.2007.09.025
[Abstract](48) [FullText HTML] [PDF 449KB](0)
Abstract:
Nine pigment-protein complexes were separated and characterized from intact Chroomonas placoidea chloroplasts by IEF. The bands Ⅰ-Ⅵ with their isoelectric points (pI) values from 4 to 6 were phycocyanin components; bands Ⅷ and Ⅸ (pI=2.8-3.6) were chlorophyll-protein complexes. According to absorption and fluorescence spectra, band Ⅶ was designated as a novel phycocyanin-Chla/c2-protein complex (pI≈3.4-3.7). These results indicated that phycocyanin is structurally and functionally coupled with chlorophyll-protein complex in C. placoidea, and probably interacted with electrostatic force in combination.
A new sesquiterpene from Caragana intermediia
Zhi Hua Sun , Chang Qi Hu , Jin Yi Wang
2007, 18(11): 1379-1382  doi: 10.1016/j.cclet.2007.09.034
[Abstract](65) [FullText HTML] [PDF 660KB](0)
Abstract:
A new alloaromadendrane-type sesquiterpene, (-)-alloaromadendrane-3β, 9β-diol (1), has been isolated from the aerial part of Caragana intermediia. The structure of (-)-alloaromadendrane-3β, 9β-diol (1) was established by spectroscopic methods, including X-ray analysis that provided its relative stereochemistry. Bioassay showed that (-)-alloaromadendrane-3β, 9β-diol (1) possesses anti-pyricularia oryzae P-2b activity with MIC value of 10 μg/mL.
Two new diterpenoids from Isodon serra
Fu Lin Yan , Lai Bin Zhang , Ji Xia Zhang , Han Dong Sun
2007, 18(11): 1383-1385  doi: 10.1016/j.cclet.2007.09.026
[Abstract](53) [FullText HTML] [PDF 225KB](0)
Abstract:
From the aerial part of Isodon serra, two new ent-6, 7-seco-kaurane-type diterpenoids, 15α, 20β-dihydroxy-6β-methoxy-6, 7-seco-6, 20-epoxy-1, 7-olide-ent-kaur-16-ene (1) and 6α, 15α-dihydroxy-20-aldehyde-6, 7-seco-6, 11α-epoxy-1, 7-olide-ent-kaur-16-ene (2) were isolated. Their structures were elucidated by spectroscopic means.
Pterisemipol,a novel sesquiterpenoid from Pteris semipinnata L.
Qiang Zhang , Li Jiang Xuan
2007, 18(11): 1386-1388  doi: 10.1016/j.cclet.2007.09.028
[Abstract](52) [FullText HTML] [PDF 255KB](0)
Abstract:
A novel sesquiterpenoid, pterisemipol, was isolated from Pteris semipinnata L. Its skeleton, namely pterisane, was considered to be rearranged from protoilludane and its structure was elucidated on the basis of spectroscopic analysis.
Gear-like array of (H2O)12 as building blocks in one-dimensional supramolecular assembly
Chun Hua Ge , Xiang Dong Zhang , Yong Chao Ma , Lei Guan , Chun Yue Shi , Xiao Yan Zhang , Ya Nan Guo , Qi Tao Liu
2007, 18(11): 1389-1391  doi: 10.1016/j.cclet.2007.07.015
[Abstract](56) [FullText HTML] [PDF 339KB](0)
Abstract:
The prepartion crystal structure of complex Co (Hsae)2·2H2O (1, H2sae=N-salicylidene-2-iminoethanol) are reported X-ray analysis revealed that every six Co (Hsae)2 forms a cyclic chip and every 12 water forms a novel gear-like cluster. Acting as building blocks, the gear-like water cluster and complex chip are connected in A-B fashion and extend into one-dimensional supramolecular chain. Hydrogen bond is the primary bridging force in the formation of supramolecular framework.
A chiral stationary phase with special hydrophobic framework for ligand-exchange chromatography
Hong Yu Shi , Rui Juan Song , Yu Fu , Na Yao , Yuan De Long , Tian Bao Huang
2007, 18(11): 1392-1394  doi: 10.1016/j.cclet.2007.09.016
[Abstract](64) [FullText HTML] [PDF 324KB](0)
Abstract:
A novel chiral stationary phase (CSP1) for ligand-exchange chromatography (CLEC) was prepared by firstly using dimethylchlorosilane as an endcapping reagent for decreasing residual silanol group on the surface of silica gel, and then introducing L-Pro as a chiral selector and hydrophobic octyl group to the silica gel surface simultaneously. The enantioseparations of 14 DL-amino acids on CSP1 were achieved with the enantioselectivity α ranging from 1.09 to 2.44 and the resolution Rs being between 0.8 and 6.3. The chromatographic performances of CSP1 with the bonded phase (CSP2) prepared using reference method were compared. The results showed that the column efficiency and resolution Rs of chiral stationary phase could be improved by using the above modifying method.
PAM-PAA microgel inverse opal photonic crystal and pH response
Yong Qiang He , Xiao Dong Wang , Jian Ying Wang , Yan Feng , Yong Qiang Zhao , Xiu Dong You
2007, 18(11): 1395-1398  doi: 10.1016/j.cclet.2007.09.010
[Abstract](51) [FullText HTML] [PDF 1056KB](0)
Abstract:
The colloidal crystal template or opal with a closed-packed face-centered cubic (fcc) lattice was prepared from monodisperse polystyrene (PS) spheres by vertical sedimentation. The template provided void space for infiltration of monomer precursor composed of acrylate acid, acrylamide and ammonium persulfate, as well as microgel from the subsequent copolymerization. The sample was immersed in dimethylbenzene for completely removing PS spheres to form PAM inverse opal hydrogels (IOHPAM) or PAM/PAA inverse opal hydrogels (IOHPAM/PAA) photonic crystals. The PS spheres were replaced by air spheres, which interconnected each other through the windows. The study of responses to pH show that there are two peaks for both IOHPAM and IOHPAM/PAA films, but the IOHPAM/PAA peaks shift to higher pH, and the peaks are independent with the AA content.
Novel preparation of organic polymer-based monolithic column by microwave irradiation
Xiong Wen Ye , Yu Ping Zhang , Ling Bo Qu , Li Qun Fan , Bo Li
2007, 18(11): 1399-1402  doi: 10.1016/j.cclet.2007.09.027
[Abstract](47) [FullText HTML] [PDF 979KB](0)
Abstract:
Microwave irradiation was firstly attempted for the preparation of organic-based monoliths of poly (styrene-divinylbenzene-methacrylic acid), which single step in situ polymerization was carried out during 15 min. The column permeability, electrophoretic and chromatographic behaviors were comparatively evaluated using pressure-assisted CEC, CEC and low pressure-driven separation modes. The largest theoretical plates for the preparing column could be close to 18, 0000 plates/m for thiourea in the mode of p-CEC. It provided a viable alternative to traditional initiation means for the preparation of monolithic capillary columns.
A novel selective fluorescent chemosensor for Cu (Ⅱ)
Mao Xiang Wang , Xiang Ming Meng , Man Zhou Zhu , Qing Xiang Guo
2007, 18(11): 1403-1406  doi: 10.1016/j.cclet.2007.09.018
[Abstract](57) [FullText HTML] [PDF 269KB](0)
Abstract:
A novel fluorescence enhancement Cu2+chemosensor derived from coumarin was prepared. Emission study found that it exhibits evident Cu2+-amplified fluorescence prior to Co2+, Pb2+, Mg2+, Mn2+, Ni2+, Zn2+, Fe3+, Ag+ and Cd2+, and the largest emission enhancement factor is about 9 at a ratio of 2:1 (chemosensor 1/Cu2+)
Synthesis of N-methylene phosphonic chitosan (NMPCS) and its potential as gene carrier
Dun Wan Zhu , Jin Gen Bo , Hai Ling Zhang , Wen Guang Liu , Xi Gang Leng , Cun Xian Song , Yu Ji Yin , Li Ping Song , Lan Xia Liu , Lin Mei , Xiu Lan Li , Yang Zhang , Kang De Yao
2007, 18(11): 1407-1410  doi: 10.1016/j.cclet.2007.09.006
[Abstract](47) [FullText HTML] [PDF 785KB](0)
Abstract:
N-Methylene phosphonic chitosan (NMPCS), an amphiphilic macromolecule with powerful chelating ability of Ca2+ ions, was synthesized and characterized. The physicochemical properties of NMPCS and the interactions between NMPCS and plasmid DNA were investigated by FTIR, 13C NMR, X-ray, agarose gel electrophoresis retardation assay, atomic force microscopy (AFM) and complexes with mean size of 80-210 nm were formed. Taking HeLa as host cell, luciferase expression mediated by NMPCS improved about 100 times compared to the expression mediated by chitosan.
Electro-generation of TGA by Ni-mSA-mCS bipolar membrane
Zhen Xia Huang , Xi Zheng , Ri Yao Chen , Xiao Chen , Zhen Chen
2007, 18(11): 1411-1415  doi: 10.1016/j.cclet.2007.09.031
[Abstract](46) [FullText HTML] [PDF 447KB](0)
Abstract:
Ni-mSA-mCS bipolar membrane (BM) was prepared by sodium alginate (SA) and chitosan (CS), which were modified by Ca2+ and glutaraldehyde as linking reagents, respectively. mSA-mCS membrane was characterized by FTIR, SEM, TG and used as a separator in the electrolysis cell to produce thioglycolic acid (TGA). The experiment results show that TGA was prepared effectively by electro-reduction of dithiodiglycolic acid (DTDGA) with the mixture of TGA and DTDGA in the cathodic chamber. The current efficiency was up to 66.7% at the room temperature (25℃) during the current density of 10 mA/cm2. Compared with the traditional metal reduction method, the electro-reduction technology saves the zinc powder and eliminates the pollution to environment.
Antioxidant activity of bovine serum albumin binding amino acid Schiff-bases metal complexes
Rong Min Wang , Juan Juan Mao , Jing Feng Song , Cai Xia Huo , Yu Feng He
2007, 18(11): 1416-1418  doi: 10.1016/j.cclet.2007.09.015
[Abstract](57) [FullText HTML] [PDF 496KB](0)
Abstract:
Glutamic acid-salicylaldehyde Schiff-base metal complexes are bound into bovine serum albumin (BSA), which afforded BSA binding Schiff-base metal complexes (BSA-SalGluM, M=Cu, Co, Ni, Zn). The BSA binding metal complexes were characterized by UV-vis spectra and Native PAGE. It showed that the protein structures of BSA kept after coordinating amino acid Schiff-bases metal complexes. The effect of the antioxidant activity was investigated. The results indicate that the antioxidant capacity of BSA increased more than 10 times after binding Schiff-base metal complexes.
Clustering properties of partly charged superfine particles in a light medium
Jing Sheng Li , Juan Wang , Qin Shen
2007, 18(11): 1419-1422  doi: 10.1016/j.cclet.2007.09.001
[Abstract](53) [FullText HTML] [PDF 288KB](0)
Abstract:
This paper investigated average cluster sizes (ACS) and cluster size distributions (CSD) at different shear rates by Brownian dynamics in non-, bi-, and uni-polar systems with partly charged superfine particles. The investigation indicates that clusters in nonpolar systems are the weakest and easiest to be damaged by increasing shear stresses; charged particles play important and different roles:in bi-polar system, it intends to strengthen clusters to some extent provided that the sign-like ions homogeneously arranged; in uni-polar system charged particles cracked the clusters into smaller ones, but the small clusters are strong to stand with larger shear stress. The relationship between ACS and shear rates follows power law with exponents in a range 0.18-0.28, these values are in a good agreement with experiment range but at the lower limit compared with other systems of non-metallic cluster particles.
Relation between the permeability and the degree of coil overlap of polymer in the bulk state
Quan Fu An , Jin Wen Qian , Meng Wang , Yin Lu , Phillip Choi
2007, 18(11): 1423-1426  doi: 10.1016/j.cclet.2007.09.007
[Abstract](38) [FullText HTML] [PDF 274KB](0)
Abstract:
Based on the expression of the index of coil interpenetration (i. e., the degree of coil overlap, ξb) of amorphous polymers in the bulk state proposed by Qian, the ξb was rewritten as ξb=ρb[η]θ/1.66 via Flory's intrinsic viscosity equation at theta conditions. The ξb of poly (vinyl chloride) (PVC) dense membranes with different molecular weights and cellulose diacetate (CA) dense membranes prepared using different solvents were determined. The permeability, permeation coefficient (P) of nitrogen and permeation flux (J) of liquid through both membranes, respectively, was measured. P and J decreased exponentially with increasing ξb for PVC and CA membranes were revealed.
Temperature waves in chemical reaction-diffusion-heat conduction systems with two ends respectively subject to Dirichlet and no-flux conditions
Yu Min Han , Zhi Li , Jiu Li Luo
2007, 18(11): 1427-1430  doi: 10.1016/j.cclet.2007.09.021
[Abstract](55) [FullText HTML] [PDF 289KB](0)
Abstract:
Taking the Lindemann model as a sample system in which there exist chemical reactions, diffusion and heat conduction, we found the theoretical framework of linear stability analysis for a unidimensional nonhomogeneous two-variable system with one end subject to Dirichlet conditions, while the other end no-flux conditions. Furthermore, the conditions for the emergence of temperature waves are found out by the linear stabiliy analysis and verified by a diagram for successive steps of evolution of spatial profile of temperature during a period that is plotted by numerical simulations on a computer. Without doubt, these results are in favor of the heat balance in chemical reactor designs.
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