bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and Thermal Decomposition Kinetics of Uranium(VI) Complex with Unsymmetrical Schiff Base Ligand
Authors: BI Cai‐Feng , ZHANG Xia , FAN Yu‐Hua , BI Shuang‐Yu , YU Hai‐Qin
Published: February 2008

A new unsymmetrical tetradentate Schiff base ligand N‐(5‐chloro‐2‐hydroxy‐α‐phenylbenzylidene)‐N′‐(2‐hydroxy‐3‐methoxybenzylidene)‐o‐phenylenediamine (H2L) was synthesized using 5‐chloro‐2‐hydroxybenzophenone, o‐phenylenediamine and o‐vanillin. A solid UO2(II) complex of this ligand [UO2(HL)(NO3)(H2O)]·H2O was prepared and characterized by elemental analyses, IR, UV, 1H NMR spectra and molar conductance. The thermal decomposition kinetics of the complex for the third stage was studied under a non‐isothermal condition by TG and DTG methods. The kinetic equation may be expressed as: dα/dt=A·e−E/RT·3/2[(1−α)−1/3−1]−1. The kinetic parameters (E, A), activation entropy ΔS≠ and activation free‐energy ΔG≠ were also gained: E=69.08 kJ/mol, ln A=20.63, r=0.9867, ΔS≠= −79.84 J·mol−1·K−1 and ΔG≠=120.6 kJ/mol.
Layer‐by‐layer Assembly of Noble Metal Nanoparticles on Glassy Carbon Electrode
Authors: CHEN Da , ZHENG Long‐Zhen
Published: February 2008

Silver, gold, platinum and palladium nanoparticles were initially prepared in the AOT [sodium bis(2‐ethylhexyl)‐ sulfosuccinate] micelle and characterized by ultraviolet‐visible spectroscopy, transmission electron macroscopy, X‐ray diffraction, Fourier transform‐infrared spectroscopy, and zeta potential analysis. The negatively charged Pt nanoparticles were self‐assembled on a glassy carbon electrode by a layer‐by‐layer method and the modified electrode electrocatalytic reactivity toward methanol oxidation was studied.
A Simple and Novel Route for The Preparation of Chiral Sodium Zincophosphate
Authors: LIAO Sen , WU Wen‐Wei , SUN Ya‐Bo , SONG Bao‐Ling
Published: February 2008

A simple and novel route for the preparation of chiral sodium zincophosphate (NaZnPO4·H2O) (CZP) was studied, and the target product was obtained with Na3PO4·12H2O and ZnSO4·7H2O as raw materials and polyethylene glycol‐400 (PEG‐400) as a surfactant via one step low heat solid state reaction. The product was characterized with TG/DTG, XRD, TEM and SEM. The experimental results showed that the NaZnPO4·H2O, which was all obtained from different P/Zn atomic ratios (0.9–1.15) of Na3PO4·12H2O to ZnSO4·7H2O and different ageing time (2.0–8.0 h) at 60 °C, had the same chiral crystal structures except slight difference in their crystallinity. The comparison experimental results suggest that the ageing temperature and anion control the enantiomorphism of NaZnPO4·H2O, that is, if ZnSO4·7H2O or Zn(NO3)2·6H2O were used as Zn source, the first chiral structure of space group P6122 was formed when the reaction mixture was aged at 60 °C, and the second chiral structure of space group P6522 was got when the reaction mixture was aged at room temperature.
Synthesis, Crystal Structure and Thermal Stability Study of [Cu2(bpe)X2]n (bpe=1,2‐trans‐bi(4‐pyridyl)ethene, X=Cl, Br, I)
Authors: CHEN San‐Ping , FAN Guang , GAO Sheng‐Li
Published: February 2008

A series of copper(I) halide complexes bridged by bpe (bpe=1,2‐trans‐bi(4‐pyridyl)ethene), [Cu2(bpe)Cl2]n (1), [Cu2(bpe)Br2]n (2) and [Cu2(bpe)I2]n (3) were successfully synthesized and complex 1 has been structurally characterized by a single crystal X‐ray diffraction method. Crystal data for 1 are monoclinic, space group P2(1)/c, a=0.3788(8) nm, b=1.5059(3) nm, c=1.0875(2) nm, β=96.262(4) °, V=0.6165(2) nm3, Z=2, S=1.002, final R indices [I>2δ(I)] R1=0.0288, wR2=0.0579, R index (all data) R1=0.0509, wR2=0.0615. Elemental analyses and IR spectra reveal that the complexes are of isomorphic compounds. In addition, thermogravimetric analyses were also applied to research of the thermal stability of the title complexes.
High‐rate Lithium Iron(II) Phosphate as Cathode Material for Rechargeable Lithium Batteries
Authors: ZHAO Ming , JIAO Li‐Fang , YUAN Hua‐Tang , SUN Jun‐Li , FENG Yan
Published: February 2008

High‐rate carbon coated LiFePO4 was synthesized by citric acid assistant aqueous chemical route employing polyethyleneoxide as the carbon source. The structural and electrochemical properties were intensively investigated by thermogravimetry, powder X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge‐discharge tests. The results of structural tests showed that the material consisted of small LiFePO4 particles of good phase purity and the particles of the material were coated and connected with approximate 5 wt% incompact porous carbon. The material performed very well in electrochemical measurements, and was suitable for high‐rate charge and discharge. The material exhibited stable discharge capacities of 120, 90 and 60 mAh·g−1 at 5 C, 10 C and 20 C rates respectively (1 C=150 mA·g−1, charge at 1 C).
A Highly Sensitive Resonance Rayleigh Scattering Method for the Determination of Penicillin Antibiotics with Potassium Ferricyanide
Authors: DUAN Hui , LIU Zhong‐Fang , LIU Shao‐Pu , KONG Ling
Published: February 2008

Heated in a boiling water bath, penicillin antibiotics such as amoxicillin, ampicillin, sodium cloxacillin, sodium carbenicillin and sodium benzylpenicillin could react with K3[Fe(CN)6] to form combined products in a dilute HCl medium. As a result, resonance Rayleigh scattering (RRS) intensity was enhanced greatly and new RRS spectra appeared. The maximum scattering wavelengths of the five combined products are all located at 330 nm. The scattered intensity increments (ΔI) of the combined products are directly proportional to the concentrations of the antibiotics in a certain range. The methods exhibit high sensitivity, and the detection limits for the five penicillin antibiotics are between 4.61 and 5.62 ng·mL−1. The spectral characteristics of RRS and the optimum reaction conditions were investigated. The mechanism of reaction and the reasons for the enhancement of resonance light scattering were discussed. The effects of coexisting substances have been examined, and the results indicated that the method had a good selectivity. It can be applied to the determination of penicillin antibiotics in capsule, tablet, human serum and urine samples.
Platinum Nanoparticles Modified Electrode for Rapid Electrochemical Detection of Escherichia coli
Authors: CHENG Yu‐Xiao , LIU Ya‐Jun , HUANG Jing‐Jing , FENG Zhen , XIAN Yue‐Zhong , WU Zi‐Rong , Zhang Wen , JIN Li‐Tong
Published: February 2008

A platinum nanoparticles chemically modified electrode (PtNP/GCE) was fabricated by electro‐deposition and used to detection of Escherichia coli (E. coli). The detection principle was based on determination of p‐aminophenol that was produced by an enzymatic reaction in E. coli solution. The sensitivity of the detection was improved by the platinum nanoparticle modified electrode and optimization of the detection system. The current responses were proportional to the density of E. coli ranging from 50 to 1.0×105 cfu/mL, with detection limit of 20 cfu/mL, and the detection time was less than 4 h. Compared with conventional methods, the electrochemical technology described here could be suitable for rapid detection of E. coli in the fields of food industry, environmental monitoring and clinic biomedicine.
Studies on Chromatographic Properties of Perhydroxycucurbit[6]uril as a New Type of Gas Chromatographic Column Packing Material
Authors: LI Lai‐Sheng , WANG Shang‐Wen , CHEN Xiong‐Quan , LIU Chao , XU Li‐Li
Published: February 2008

Perhydroxycucurbit[6]uril {(HO)12CB[6]} has been used successfully as a stationary phase for packed column gas chromatography for the first time. Perhydroxycucurbit[6]uril stationary phase (PSP) exhibited wide operational temperature, outstanding thermostability and good selectivities to various organic compounds, such as alkanes, aromatic hydrocarbons, alcohols, esters, ketones, amines, etc. It was also found that some positional isomers, such as disubstituted benzenes could be well separated on this column. PSP has excel1ent separation abilities to some complicate samples, for example, commercial toilet water. Some mechanism of the new packing for GC‐separation was preliminarily discussed. It was observed that the partial inclusion complexation of PSP with analytes could improve separation selectivity and column efficiency, instead of complete inclusion. Moreover, PSP exhibited low baseline shift even at dramatically programmed temperature for complicate samples covering a wide boiling point range so as to fast assay.
Ru(bpy)32+‐doped Silica Nanoparticle Aptasensor for Detection of Thrombin Based on Electrogenerated Chemiluminescence
Authors: WANG Xiao‐Ying , YUN Wen , ZHOU Jing‐Ming , DONG Ping , HE Pin‐Gang , FANG Yu‐Zhi
Published: February 2008

A new electrogenerated chemiluminescent (ECL) detection system for protein using the aptamers was developed. Two different aptamers, which recognize different positions of thrombin, were chosen to construct sandwich type sensing system for protein, one was immobilized onto the gold electrode for capturing thrombin onto the electrode and the other was used for detection. To obtain the signal, the aptamer for detection was labeled with tris(2,2′‐bipyridyl)ruthenium(II)‐doped silica nanoparticles (Ru(bpy)32+‐doped SNPs). The increase of the ECL signal generated by Ru(bpy)32+‐doped SNPs was observed in dependent manner on the concentration of thrombin added. Bovine serum albumin and bovine hemoglobin had almost negligible responses. The assay allows detection at levels as low as 1.0 fmol·L−1 of the thrombin due to that there are a large number of Ru(bpy)32+ molecules inside SNPs labeled on the aptamer used for detection. The ECL signal was linearly related to the concentration of the thrombin analyte in the range of 2.0 fmol·L−1 to 2.0 pmol·L−1.
A Novel Metal‐free and Highly Efficient Hydroarylation of Styrenes Catalyzed by Molecular Iodine
Authors: SUN Gao‐Jun , ZHANG Tai‐Chang , SHENG Liu‐Si , QI Fei , WANG Zhi‐Yong
Published: February 2008

A molecular iodine catalyzed hydroarylation of styrenes by arenes has been developed. This reaction could be carried out at 25 °C under a solvent‐free condition, giving rise to the corresponding products with yields up to 93%. A series of 1,1‐diarylalkane derivatives were easily prepared without any involvement of metal catalysts.
Synthesis and Properties of Two Second‐Order Nonlinear Optical Polymers: an Attempt toward the Balance between Nonlinearity and Transparence against Intrinsic Trade‐off
Authors: LI Su‐Yue , LI Zhong‐An , ZHU Zhi‐Chao , ZHANG Wei , HUANG Ting , LI Zhen , YE Cheng , QIN Jin‐Gui
Published: February 2008

Two new poly(arylene ether sulfone)s (P1 and P2) with two new accepting group (TCF)‐based chromophores (1 and 2) in side chains, respectively, were designed and synthesized. The two chromophores contain the same electron donating group (dialkylamino group) and the same accepting group (TCF), but different conjugation bridges. Compound 2 contains a combined conjugation bridge (phenyl‐diazene plus styrene), but the bridge of 1 is much shorter (styrene only). A variety of optical properties were studied. Compared with P1, P2 exhibited comparable nonlinear optical coefficient (d33) and better transparency (the maximum absorption was blue‐shifted by 16 nm), though the conjugation bridge of chromophore 2 in P2 was much longer than that of 1 in P1. This result may help design nonlinear optical polymers achieving the balance between nonlinearity and transparence against the intrinsic trade‐off.
Poly(diallyldimethylammonium chloride) as an Efficient Phase Transfer Catalyst in Solvent‐Free Reduction of Carbonyl Compounds with NaBH4
Authors: MAHDAVI Hossein , HAGHANI Ekram
Published: February 2008

Poly(diallyldimethylammonium chloride) resin was used as an efficient polymeric phase transfer catalyst, which catalyzed the chemoselective reduction of aldehydes and ketones by NaBH4 to give the corresponding alcohols in high yields under solvent‐free conditions.
Synthesis of Andrographolide Glucopyranoside and Selective Cleavage of O‐acetyl Groups in Sugar Moiety
Authors: WANG Shao‐Min , LIU Hong‐Min
Published: February 2008

Andrographolide glucopyranosides were synthesized from andrographolide and tetra‐O‐acetyl‐β‐D‐gluco‐ pyranosyl bromide via a Koenigs‐Knorr reaction and deacetylation with a moderate deacetylation reagent dibutyltin oxide in methanol for the first time. The structures of the andrographolide derivatives were confirmed by IR, NMR, and HRMS. Deprotection of the acetylated andrographolide glucopyranoside with dibutyltin oxide in methanol selectively removed all acetyl groups of the sugar moiety, whereas the acetyl group of the andrographolide part and the base‐ or acid‐sensitive functional groups were retained.
Further Daphniphyllum Alkaloids from the Bark of Daphniphyllum macropodum Miq.
Authors: LI Zhen‐Yu , CHEN Ping , XU Hong‐Gui , PENG Shu‐Ying , YANG Yi‐Ming , ZHAO Zhong‐Zhen , Guo Yue‐Wei
Published: February 2008

Four new Daphniphyllum alkaloids, namely dehydroxymacropodumine A (1), 4,21‐deacetyl‐23‐demethyl‐deoxyyuzurimine (2), 7‐oxo‐deoxyyuzurimine (3), and 4‐acetoxydaphmanidin B (4), together with seven known related alkaloids, were isolated from the bark of Daphniphyllum macropodum Miq. The structures of new compounds 1–4 including relative configurations were elucidated on the basis of detailed spectroscopic data analysis and by comparison with related known compounds. Dehydroxymacropodumine A (1) possesses a rare eleven‐membered macrolactone ring representing the second example of this backbone isolated from natural sources.
Enantioselective Hydrogenation of Aromatic Ketones Catalyzed by Ru Complex Using a New Bipyridyl Diphosphine
Authors: CHEN Li , FU Xing‐Li , MING Fang‐Yong , CHEN Hua , LI Xian‐Jun
Published: February 2008

A series of RuCl2(bipyridyldiphosphine)(1,2‐diamine) complexes were synthesized and applied to the asymmetric hydrogenation of aromatic ketones. Solvent effect and a wide variety of aromatic ketones were explored and up to 96% enantioselectivity was achieved in the hydrogenation of o‐bromoacetophenone.
Theoretical Study on Catalyst Activation of Palladacycles in Heck Reaction
Authors: WANG Chen , FU Yao , LI Zhe , GUO Qing‐Xiang
Published: February 2008

A computational study with the B3PW91 density functional theory was carried out on the activation process of palladacycles as catalysts in the Heck reaction. Two possible pathways (i.e. anion reductive cleavage of the Pd–C bond, and olefin insertion into the Pd–C bond followed by β‐H elimination) were taken into consideration. Computational results indicate that the palladacycles are activated via olefin insertion into the Pd–C bond followed by β‐H elimination in the reaction conditions.
Cascade Reaction and Synthesis of Bicyclo[2,2,2]octenones
Authors: LI Nian‐Guang , WANG Jin‐Xin , YOU Qi‐Dong , CHU Gang , GUO Qing‐Long
Published: February 2008

During study on the remarkable cascade reaction for synthesis of compound 1, the neo‐caged scaffold 2 with a heterocyclic bicyclo[2.2.2]octenone moiety and two new allyl substituted xanthones 3, 4 were obtained besides the known caged scaffold 1. The probable reaction processes were also elucidated in this paper.
An Environmentally Benign Access to Dimethylated 1,6‐Dihydropyrimidines Using Dimethyl Carbonate as Methylating Agent under Microwave
Authors: WANG Xi‐Cun , QUAN Zheng‐Jun , ZHANG Zhang
Published: February 2008

An environmentally benign procedure for dimethylated 1,6‐dihydropyrimidines has been developed by the reaction of 1,2,3,4‐tetrahydropyrimidine‐2‐thiones with dimethyl carbonate, a non‐toxic and environmentally friendly reagent. The methylation of 1,2,3,4‐tetrahydropyrimidine‐2‐thione was promoted by MgO and tetrabutylammonium bromide (TBAB) under microwave. This protocol avoids the use of strong bases and highly toxic methylating agents such as methyl halide or dimethyl sulfate. Additionally, the possible role of MgO/TBAB in the reaction was also presented.
Bifunctional Enantioselective Ligands of Chiral BINOL Derivatives for Asymmetric Addition of Alkynylzinc to Aldehydes
Authors: ZOU Xiao‐Wei , ZHENG Li‐Fei , WU Ling‐Lin , ZONG Li‐Li , CHENG Yi‐Xiang
Published: February 2008

Four analogous binaphthyl compounds (R)‐3a‐3d containing (R)‐3,3′‐bis(2‐pyridyl) groups were synthesized by the conjugation of (R)‐2,2′‐dimethoxy‐1,1′‐binaphthyl‐3,3′‐diboronic acid [(R)‐2] with 2‐bromopyridine, 2‐bromo‐5‐methylpyridine, 2‐chloro‐4‐fluoropyridine and 2‐chloro‐3‐(trifluoromethyl)pyridine via Pd‐catalyzed Suzuki reactions, respectively. The application of the four chiral ligands in combination with Et2Zn and Ti(Oi‐Pr)4 to the asymmetric addition of phenylacetylene to various aldehydes has been studied. The results show that (R)‐3a and (R)‐3b are not good catalysts for the alkynylzinc addition to aldehydes, (R)‐3d shows good enantioselectivity only for the alkynylzinc addition to aliphatic aldehydes, and (R)‐3c exhibits excellent enantioselectivity for phenylethynylzinc addition to both aromatic and aliphatic aldehydes. All the four chiral ligands produced the opposite configuration of the propargylic alcohols to that of the chiral ligands.
Synthesis and HIV‐1 Reverse Transcriptase Inhibitory Activity of Non‐Nucleoside Phthalimide Derivatives
Authors: UNGWITAYATORN Jiraporn , WIWAT Chanpen , MATAYATSUK Chutima , PIMTHON Jutarat , PIYAVIRIYAKUL Suratsawadee
Published: February 2008

A new type of non‐nucleoside HIV‐1 reverse transcriptase inhibitors in phthalimide series has been synthesized from either the reaction of N‐carboethoxyphthalimide with amines or phthalimide with appropriate alkyl halides. The in vitro inhibitory activity of the synthesized compounds was studied by a radiometric assay at a concentration of 200 µg/mL using poly(rA)·oligo(dT) as a template‐primer and methyl‐[3H]dTTP as a substrate. The three most potent compounds, N‐(m,p‐dihydroxybenzyl)phthalimide (11), N‐[2‐(α‐furyl)ethyl]phthalimide (29) and N‐(5‐methylpyrazin‐2‐ylmethyl)phthalimide (25) exhibited IC50 values of 60.90, 98.10 and 120.75 µg/mL, respectively, lower than IC50 of delavirdine (502.22 µg/mL, using poly(rA)·oligo(dT) as a template‐primer and [3H]dTTP as a substrate).
Synthesis of Some New Heterocycles Derived from Phenylacetyl Isothiocyanate
Authors: HEMDAN M. M. , FAHMY A. F. , ALI N. F. , HEGAZI E. , ABD‐ELHALEEM A.
Published: February 2008

Phenylacetyl isothiocyanate (1) was reacted with benzoyl hydrazine (2a) in acetonitrile to give thiosemicarbazide derivative 3 which was cyclized by polyphosphoric acid to give 1,2,4‐triazoline‐5‐thione derivative 4. Treatment of 1 with thiosemicarbazide (2b) yielded another 1,2,4‐triazoline‐5‐thione derivative 5. Similar treatment of 1 with phenyl hydrazine (2c) in acetonitrile gave a differently substituted 1,2,4‐triazoline‐5‐thione derivative 6 in one pot‐reaction. On the other hand, when the reaction was carried out in acetone, a mixture of 6 and thiadiazolidine derivative 7 was obtained. However, reaction of 1 with hydrazine hydrate (2d) gave hydrazine derivative 8. Reaction of isothiocyanate 1 with anthranilic acid (9) gave benzo[d][1,3,6]oxazin‐1‐one derivative 10. Treatment of 1 with 2‐aminothiophenol (11a), 2‐aminophenol (11b) or o‐phenylenediamine (11c) produced benzothiazole derivative 12a, benzoxazole derivative 12b and benzimidazole derivative 12c, respectively. The structures of all the products were confirmed by micro‐analytical and spectral data.
Theoretical Study on the Mechanism of the Gas‐phase Reaction of Sc+ with Propargyl Alcohol
Authors: ZHANG Yi‐Ping , CHEN Hong‐Yan , CHENG Wei‐Xian , FENG Yu , YANG Li‐Jun
Published: February 2008

In order to elucidate the reaction mechanisms of reaction Sc+ with propargyl alcohol (PPA), the triplet potential energy surface for the reactions has been theoretically investigated using a DFT method. The geometries for the reactants, intermediates, transition states and products were completely optimized at B3LYP/DZVP level. The single point energy of each stationary point was calculated at MP4/(6‐311+G∗︁ ∗︁ for C, H, O and Lanl2dz for Sc+) level. All the transition states were verified by the vibrational analysis and the internal reaction coordinate (IRC) calculations. The present results show that the reaction takes an insertion‐elimination mechanism both along the OH and CO bond activation branches, but the CO bond activation is much more favorable in energy than the OH bond activation. All theoretical results not only support the existing conclusions inferred from early experiment, but also complement the pathway and mechanism for this reaction.
Spectroscopic Investigation on the Interaction of a Cyanine Dye with Serum Albumins
Authors: ZHANG Ya‐Zhou , YANG Qian‐Fan , DU Hong‐Yan , TANG Ya‐Lin , XU Guang‐Zhi , YAN Wen‐Peng
Published: February 2008

The interactions of a cyanine dye with human serum albumin (HSA) and bovine serum albumin (BSA) have been investigated by using absorption and fluorescence spectra. Absorption spectral studies show that binding to the serum albumins leads to a bathochromic shift of the monomer band together with a notable intensity change. Furthermore, the number of binding sites (n) was identified by the absorption spectra. There is a constant enhancement of fluorescence quantum yield when the cyanine dye complexes with HSA or BSA. The apparent binding constant (Ka) and the free energy changes (ΔG) were obtained by analysis of fluorescence data of the cyanine dye in the absence and presence of HSA and BSA. Compared to BSA, HSA associates with the dye in a stronger way.
Sodium Arsenite Induced Alteration of Hemocyte Density of Lamellidens marginalis – An Edible Mollusk from India
Authors: Chakraborty Sudipta , Ray Mitali , Ray Sajal
Published: February 2008

Lamellidens marginalis (Molluska Bivalvia Eulamellibranchiata) is an important member of the freshwater ecosystem of India, which is sustained by filtering phytoplankton, bacteria and other particulate organic matter from the available water. Hemocytes, the circulating blood cells of bivalves, function as immunological effector cells under exposure to toxins and/or parasites. The hemocytes of Lamellidens marginalis have been identified morphologically and enumerated as being qualified for use as a biomarker to analyze the threat of freshwater contamination by sublethal concentrations of sodium arsenite, a natural pollutant of freshwater ecosystems. Diverse subpopulations of hemocytes were identified as blast‐like cells, granulocytes, agranulocytes, hyalinocytes and asterocytes. Supression in the total count of hemocytes and blast‐like cells was recorded under the exposure of all the concentrations of sodium arsenite tested. Sodium arsenite elevated the relative density of granulocytes, hyalinocytes, and asterocytes. Partial restoration of the total count of the hemocytes was recorded after the post‐treated animals were maintained in arsenic‐free water for periods of 15 and 30 days. The data predict a shift in the immunological parameters of this bivalve in arsenic contaminated environments. The present study is aimed at quantifying the arsenic induced stress in Lamellidens marginalis and establishing the hemocyte density as a biomarker of aquatic pollution in selected geographical regions of India.
Permselective Membrane Fouling During Azo Dye Wastewater Treatment
Authors: Oduor Peter G. , Santos Xiana , Abwawo Jared , Dunham Jeffery
Published: February 2008

A Na‐montmorillonite membrane wastewater renovation prototype system was developed to specifically treat an ionic azo dye. Efficiency of this prototype system was limited to membrane fouling. Fouling rates were not consistently uniform owing to steric effects and competition for exchange sites. The decrease in solute rejection with time can be attributed to the decrease in the relative permeability of the compacted Na‐montmorillonite membrane to the dye with time due to fouling. This decrease occurs probably as a two‐step nucleation–growth mechanism with the nucleation part dependent in part on solvent flux, number of nucleation sites on the membrane, and sorbed mass part that controls solute flux and organic polymerization. The effect of concentration polarization was significant since the flux was higher than the mass‐transfer coefficient. The low diffusion coefficient of the ionic azo dye resulted in low mass transfer coefficients. The most important macromolecular solution properties to be considered for pilot systems may include high concentration‐dependent viscosity, possible non‐Newtonian fluid behavior, and low and concentration‐dependent self‐diffusivity amongst other factors. For pilot systems, the greater the quantity of large macromolecules in the ambient water, the greater the necessity of reducing the permselectivity of the membrane to prevent significant polarization.
Assessment of Trace Metal Contamination of Drinking Water in the Pearl Valley, Azad Jammu and Kashmir
Authors: Javaid Saboor , Shah Syed Ghulam Sarwar , Chaudhary Abdul Jabbar , Khan Mohammad Haleem
Published: February 2008

The aim of this study was to assess trace metal contamination of drinking water in the Pearl Valley, Azad Jammu and Kashmir (Pakistan). The objectives were to determine physical properties and the dissolved concentration of five trace metals, i. e., lead, copper, nickel, zinc, and manganese, in drinking water samples collected from various sites of municipal water supply, natural water springs and wells in the valley. Concentrations of the metals in the water samples were determined by flame atomic absorption spectrometry. Results showed physical parameters, i. e., appearance, taste and odor within acceptable limits and pH was between 5.5 and 7.0. The observed concentrations of the metals varied between sources of water samples and between sampling sites. Maximum dissolved concentration observed was 4.7 mg/L for Pb and Mn, 4.6 mg/L for Zn, 2.9 mg/L for Ni and 2.8 mg/L for Cu. The observed concentrations of the metals were compared with the World Health Organization's guideline values for drinking water. Overall, the quality of water samples taken from the water springs at Mutyal Mara and Bonjosa was good; however, the water quality was unsuitable for drinking in Kiraki, Kharick, and Pothi Bala localities particularly. Finally, the authors discuss possible causes for increased concentrations of the trace metals in drinking water in the study area.
Hazardous Waste Pollution Prevention Using Clay with Admixtures
Authors: Saha Papita , Datta Siddhartha , Sanyal Shyamal Kanti
Published: February 2008

Landfill is the most commonly used method for disposal of waste materials since it is one of the least expensive methods. In order to dispose of any hazardous material to a landfill, a liner is used, which protects the underlying land and groundwater since it acts as a barrier to fluid movement. Of the various methods available for providing improved and more effective properties of landfills, methods involving the use of bentonite, cement, lime, gypsum, etc., have been explored in the laboratory. The aim is to overcome the problem and deficiencies of the existing liners. It is observed from the experimental results that the metal concentrations of the input waste solution can be reduced to 80–98% using a soil‐cement admixture, 60–95% using a soil‐gypsum mixture, 45–95% using a soil‐bentonite mixture, 50–90% for soil, 35–80% using a soil‐lime mixture, as liner materials. The permeation rate of different metals through the different soil‐admixture media depends on various factors. A simple mathematical treatment of the phenomenon related to the permeation of liquid through the admixture of the clay and other components has been developed. The experimental results show satisfactory agreement with the predictions.
Persistent Organic Pollutants (POPs) in Bottom Sediments of the Vistula River, Poland
Authors: Dmitruk Urszula , Piašcik Marek , Taboryska Barbara , Dojlido Jan
Published: February 2008

The Vistula (Wisla) river, the biggest river in Poland, is 1038 km long and has a drainage area of 168 689 km2. The river is strongly polluted by wastewaters. Big industrial plants are situated mainly in the upper part of the river, where it is slow‐flowing. This paper presents the results of the analysis of bottom sediment samples gathered from different locations along the Vistula river, from Kraków to Gdansk. The study was conducted in 2005. The following parameters were determined: chloroorganic pesticides, polychlorinated biphenyls (PCBs), chlorophenols, polycyclic aromatic hydrocarbons (PAHs), total organic carbon (TOC). The sum of chloroorganic pesticides was in the range of 2.0 to 77.5 ng/g d.w. (dry wet) with the highest values in the upper part of the river. p,p′‐DDT was found in the highest concentration. The sum of PCBs was in the range of 0.9 to 64.2 ng/g d.w. The sum of chlorophenols varied from 0.48 to 14.3 ng/g d.w. 2,4‐Dichlorophenol and pentachlorophenol occurred in the highest concentration. The sum of PAHs was in the range of 1552 to 7832 ng/g d.w. Phenantren was found in the highest concentration and antracen in the lowest. TOC values varied from 4.3 to 43.9 g/kg d.w. The concentrations of pesticides and PCBs were the highest in the upper part of the river and decreased along the course of the river, but the other determined compounds did not show this trend. However, the highest values occurred always in the upper part of the river.
Dispersion Potential of Selected Iowa Lake Sediments as Influenced by Dissolved and Solid‐phase Constituents
Authors: Mathangwane Bogadi T. , Chappell Mark A. , Pils Jutta R. V. , Sonon Leticia S. , Evangelou Vasilos P.
Published: February 2008

Critics charge that agricultural managers routinely overdose their fields with chemical N and P to levels that exceed the soil's capacity to adsorb these materials, creating a situation that promotes hypoxia in Iowa lakes. Soil colloidal particles, capable of forming complexes with inorganic and organic N and P, control the equilibrium concentration of dissolved nutrients in lake waters. However, it should be realized that adsorbed nutrients also exhibit strong influences on the potential of sediments to undergo dispersion, a condition that may directly impact nutrient bioavailability. Thus, direct links may exist between adsorbed nutrient compositions and flocculation/dispersion properties of lake colloidal material. This paper presents work involving four Iowa lakes undertaken to determine relationships between ion composition and the dispersion potential of sediments. Surface waters and lake‐bottom grab samples were collected at three separate collection times from August to October. Samples were characterized for dissolved and adsorbed cations. Dispersion potential of each water sample was characterized by relating the total suspended solids concentration to the absorbance at 560 nm. It was found that sediment dispersion was easily predictable by a simple yet significant linear correlation with the concentration ratio of Na (CRNa = [Na]/[Ca]–1/2) in solution. This correlation was further improved by including Na concentration, CRK, electrical conductivity, temperature, and solution P concentrations into the model. Nonlinear inter‐dependences were found between TSS and cation exchange capacity (CEC), and adsorbed Na, K, P, and heavy metals. Our analysis suggests that solution/solid phase constituents influenced the dispersion behavior of sediments through subtle manipulations of the excess surface charge.
An Improved Gas Chromatographic Method for the Determination of C6–C12 Petroleum Hydrocarbons in Soil Water
Authors: Voyevoda Maryna , Geyer Wolfgang , Mothes Sibylle
Published: February 2008

In this work, investigations dealing with the determination of hydrocarbons in contaminated soil water are presented. The hydrocarbons under investigation range from low to high volatility compounds. A GC‐FID method was developed that due to its efficiency, routine suitability, relative rapidity, and low cost is suitable for the analysis of complex chemical mixtures of highly volatile hydrocarbons (with boiling points between 69 and 190°C). The standard used was a gasoline mixture with boiling points ranging from 100 to 190°C. For this standard, no supplementary preparation is needed and it is suitable for the whole range of hydrocarbons under investigation. The determination of the hydrocarbon content of the samples was performed applying univariate and multivariate statistical analysis to the experimental data. In the characterization of a contamination with highly volatile hydrocarbons of soil water originating from different depth layers from the chemistry location Leuna (Sachsen‐Anhalt, Germany), the advantages of a multivariate method are demonstrated in exemplary manner.
Fatty Acid Composition of Plankton and Bighead Carp (Aristichthys nobilis) in Freshwater Ponds
Authors: Guo Ganlin , Dong Shuanglin , Zhao Wen , Chen Wei
Published: February 2008

The community structure and fatty acid composition of plankton in broodstock ponds were studied at the Bishui Fisheries Company in the Liaoning Province, northeast China, between May and December 2002 and in March 2003. The Fatty acid analysis of bighead carp larvae and plankton in the fry pond occurred during June, July, and September 2002. The fatty acid composition of the plankton varied with seasonal changes in the community structure. When blue‐green algae dominated the broodstock ponds in spring and summer, the percentage of saturated fatty acids (SFA) (especially 16:0) was high. When diatoms and cryptophytes dominated in autumn and winter, the percentage of polyunsaturated fatty acids (PUFAs) (mainly n–3 PUFA) was high. Similarly, a high content of docosahexaenoic acid (DHA) occurred in autumn and winter when DHA‐rich copepods became an important group of zooplankton. In addition, environmental factors, especially water temperature, influenced the fatty acid composition of plankton. 16:0, DHA, and 18:1n–9 were dominant fatty acids of bighead carp larvae during ontogeny. 16:0, C18 unsaturated fatty acids, and eicosapentaenoic acid (EPA) were major fatty acids of plankton in the fry pond. Analysis of the relationship between the fatty acids of the larvae and those of plankton showed that the fatty acid profiles of the larvae did not always agree with those of plankton.
Green Electronics through Legislation and Lead Free Soldering
Authors: Herat Sunil
Published: February 2008

Management of used electrical and electronic equipment (EEE) is becoming a major issue as each year around 20 to 50 million tonnes of electronic waste (e‐waste) is generated worldwide. EEE contains over 1000 materials of which lead (Pb) has been one of the targets of the regulators forcing manufacturers to adopt lead free products. Industry has come up with several lead free solders with preference given to alloys containing tin, silver, and copper but there is no ,drop‐in' substitute to leaded solder. Issues with lead free solders such as temperature, intermetallics, tin whisker, tin pest, and reliability are yet to be resolved. The paper investigated the contribution of lead free soldering to green electronics in a holistic way. Global lead free movement has reached a point of no return. However, it is necessary to make sure that life span of EEE is not shortened thereby resulting in an unforeseen increase in e‐waste or problem shifting does not occur by shifting a problem from one life cycle to another or from one category/media to another.
Catalytic Destruction of 4‐Chlorophenol in Water
Authors: Chaliha Suranjana , Bhattacharyya Krishna Gopal , Paul Parimal
Published: February 2008

4‐Chlorophenol (4‐CP) is a toxic, hazardous and persistent pollutant entering water mainly via the effluents of chemical industries. Catalytic wet oxidation has been the favored green chemistry path to convert this chlorinated organic to benign products. Wet oxidation was attempted in this work with MCM‐41 based catalysts impregnated with Fe(III), Co(II), and Ni(II). The catalysts were characterized with X‐ray diffraction, scanning electron microscopy, FTIR, cation exchange capacity, and atomic adsorption spectrophotometric measurements. 4‐CP oxidation was carried out in water, with and without hydrogen peroxide. The efficiency of the catalysts was tested with respect to reaction time, pH, mole ratio of the reactant and the oxidant, catalyst load, feed concentration, and temperature. The typical reaction conditions of temperature of 353 K, time 300 min, catalyst load 2 g/L, 4‐CP concentration 10–3 M could achieve 50.2, 55.0 and 58.2% oxidation in the presence of H2O2 and 48.5, 58.6 and 60.2% oxidation in the absence of H2O2 with Fe(III)‐, Co(II)‐, and Ni(II)‐MCM‐41, respectively. The reactions followed pseudo‐first‐order kinetics with respect to 4‐CP and the kinetic constant was between 1.4·10–3 and 3.5·10–3 Lg–1min–1. A mechanism for the oxidation of 4‐CP is suggested on the basis of product analysis.
Fe, Mn, P and S Speciation in Sediments from the Capivara Hydroelectric Dam Lake (Brazil) as an Indicator of Anthropogenic Influences
Authors: Barreto Wagner José , Ishikawa Dilson Norio , Spacino Scarminio Ieda , de Souza Costa João , dos Santos Nora Paulo , de Fatima Soares Miriam , Mansano Nicolau Romilaine , Esteves Gonçalves Adriana Celeste , Giancoli Barreto Sonia Regina
Published: February 2008

The conservation of large water resources is essential for the preservation of human life. The quantification and, more importantly, the speciation of chemical substances that indicate the presence of anthropogenic contamination in water resources are of great importance. This paper presents the results of analysis for the determination of organic, inorganic and total phosphorus, pseudo‐sulfur, and iron and manganese, in five fractions, in water sediments collected from the Capivara Hydroelectric Power Plant, Brazil. A study on the seasonal variation of these parameters was conducted, with data having been collected in the winter and in the summer, at two sites along the dam, 5 km apart, close to the city of Primeiro de Maio. Phosphorous was found in sediments and adjacent soil in the organic form (OP), and was used as an indicator of anthropogenic influence on the reservoir banks. Speciation of potentially toxic Mn showed that it is present in the exchangeable fraction of the 0–5 cm depth layer (sediment/water interface), making its transfer to the water column possible. Results from this study showed that domestic and industrial effluent treatment measures are needed for the preservation of the quality of aquatic environments.
Spectroscopic Characterization of Compost at Different Maturity Stages
Authors: Spaccini Riccardo , Piccolo Alessandro
Published: February 2008

We studied the physicochemical and molecular changes of compost during its maturation within 60, 90, and 150 days after the composting process. Moreover, the changes were also studied in compost residues after sequential removal of lipidic compounds. Infrared DRIFT spectrometry and 13C‐CPMAS‐NMR spectroscopy indicate that the molecular composition of compost changes dramatically during the stabilization period. The most decomposable components, mainly represented by bioavailable lipidic and peptidic structures, were progressively mineralized passing from 60 days to longer periods of compost stabilization. At increasing maturity stages, the composition of organic matter underwent a progressive enrichment in stable hydrophobic and ligno‐cellulosic material. The sequential extraction of lipidic compounds allowed an improved characterization of substrates and confirmed the outlined progressive transformation of compost. Compost may well be chosen on the basis of selected characteristics for environmental applications.
Comparison of two wave element methods for the Helmholtz problem
Authors: Huttunen T. , Gamallo P. , Astley R. J.
Published: February 2008

In comparison with low‐order finite element methods (FEMs), the use of oscillatory basis functions has been shown to reduce the computational complexity associated with the numerical approximation of Helmholtz problems at high wave numbers. We compare two different wave element methods for the 2D Helmholtz problems. The methods chosen for this study are the partition of unity FEM (PUFEM) and the ultra‐weak variational formulation (UWVF). In both methods, the local approximation of wave field is computed using a set of plane waves for constructing the basis functions. However, the methods are based on different variational formulations; the PUFEM basis also includes a polynomial component, whereas the UWVF basis consists purely of plane waves. As model problems we investigate propagating and evanescent wave modes in a duct with rigid walls and singular eigenmodes in an L‐shaped domain. Results show a good performance of both methods for the modes in the duct, but only a satisfactory accuracy was obtained in the case of the singular field. On the other hand, both the methods can suffer from the ill‐conditioning of the resulting matrix system. Copyright © 2008 John Wiley & Sons, Ltd.
Eight‐node shell element based on incompatible modes
Authors: Xu Desheng , Xiao Rucheng , Wang Yan , Ling Daosheng
Published: February 2008

This paper concerns the shell element formulation used for linear analysis. Introduction of hierarchical incompatible modes into the ordinary 8‐node solid element is very effective to obtain the rational deflection–rotation relationship. An efficient revision scheme without using numerical volume integration is developed to ensure the satisfaction of the patch test. A lot of numerical tests are carried out for the validation of the present element. Numerical results show that the element can give satisfactory accuracy and convergence, especially for moderately thick shells. Copyright © 2008 John Wiley & Sons, Ltd.
An extended finite element method for hydraulic fracture problems
Authors: Lecampion Brice
Published: February 2008

In this paper, the extended finite element method (X‐FEM) is investigated for the solution of hydraulic fracture problems. The presence of an internal pressure inside the crack is taken into account. Special tip functions encapsulating tip asymptotics typically encountered in hydraulic fractures are introduced. We are especially interested in the two limiting tip behaviour for the impermeable case: the classical LEFM square root asymptote in fracture width for the toughness‐dominated regime of propagation and the so‐called ⅔ asymptote in fracture width for the viscosity‐dominated regime. Different variants of the X‐FEM are tested for the case of a plane‐strain hydraulic fracture propagation in both the toughness and the viscosity dominated regimes. Fracture opening and fluid pressure are compared at each nodes with analytical solutions available in the literature. The results demonstrate the importance of correcting for the loss of partition of unity in the transition zone between the enriched part and the rest of the mesh. A point‐wise matching scheme appears sufficient to obtain accurate results. Proper integration of the singular terms introduced by the enrichment functions is also critical for good performance. Copyright © 2008 John Wiley & Sons, Ltd.
Twist Grain Boundary Liquid‐Crystalline Phases under the Effect of the Magnetic Field: A Complete2H and13C NMR Study
Authors: Domenici Valentina , Veracini Carlo Alberto , Novotná Vladimira , Dong Ronald Y.
Published: February 2008

A liquid crystal (HZL 7/*) containing an (S)‐2‐methylbutyl‐(S)‐lactate unit in the chiral chain, is investigated by means of2H and13C NMR spectroscopy in order to obtain information on its orientational order, its molecular structure and the effect of external magnetic fields on the supramolecular structure of its phases. This mesogen presents very peculiar mesomorphic properties and exhibits frustrated TGBA* and TGBC* phases in a wide temperature range up to 60 °C, as well as an additional phase transition from TGBC1* to TGBC2*.2H NMR measurements show, for the first time, a peculiar magnetic field effect in unwinding the supramolecular structure of both the TGBA* and TGBC* phases. This effect is particularly evident at higher magnetic fields, while different behaviour is observed at lower magnetic fields. This indicates that the supramolecular structure is very sensitive to magnetic fields of the order of 1 Tesla. Moreover, the analysis of the2H and13C NMR spectra ofHZL 7/*allow us to obtain several structural properties, such as the tilt angle of the TGBC* phases and the local orientational order parameters referred to the phenyl and biphenyl fragments. This is the first structural characterization of the frustrated phases of these complexes by means of NMR.
Listening to Lanthanide Complexes: Determination of the Intrinsic Luminescence Quantum Yield by Nonradiative Relaxation
Authors: Yang Yuetao , Li Junjia , Liu Xiaojun , Zhang Shuyi , Driesen Kris , Nockemann Peter , Binnemans Koen
Published: February 2008

The photophysical properties of lanthanide complexes have been studied extensively; however, fundamental parameters such as the intrinsic quantum yield as well as radiative and nonradiative decay rates are difficult or even impossible to measure experimentally. Herein, a photoacoustic (PA) method is proposed to determine the intrinsic quantum yield of lanthanide complexes with lifetimes in the order of milliseconds. This method is used to determine the intrinsic quantum yields for europium(III)‐containing metallomesogens as well as terbium(III) complexes. The results show that the PA signal is sensitive to both the lifetime and the ratio of the fast‐to‐slow heat component of the samples. It is found that there is an efficient ligand sensitization and a moderate intrinsic quantum yield for the complexes. The intrinsic quantum yield of Eu3+ in the metallomesogens exhibits an obvious increase upon the isotropic liquid to smectic A transition. The proposed PA method is quite simple, and can contribute to a clearer understanding of the photophysical processes in luminescent lanthanide complexes.
Ionic Liquids: Dissecting the Enthalpies of Vaporization
Authors: Köddermann Thorsten , Paschek Dietmar , Ludwig Ralf
Published: February 2008

We calculate the heats of vaporisation for imidazolium‐based ionic liquids [Cnmim][NTf2] with n=1, 2, 4, 6, 8 by means of molecular dynamics (MD) simulations and discuss their behavior with respect to temperature and the alkyl chain length. We use a force field developed recently. The different cohesive energies contributing to the overall heats of vaporisations are discussed in detail. With increasing alkyl chain length, the Coulomb contribution to the heat of vaporisation remains constant at around 80 kJ mol−1, whereas the van der Waals interaction increases continuously. The calculated increase of about 4.7 kJ mol−1 per CH2‐group of the van der Waals contribution in the ionic liquid exactly coincides with the increase in the heats of vaporisation for n‐alcohols and n‐alkanes, respectively. The results support the importance of van der Waals interactions even in systems completely composed of ions.
Characteristics and key findings for ‘Behavioural and cognitive interventions with or without other treatment for the management of faecal incontinence in children’
Authors: van Dalen E. C. , Offringa M.
Published: February 2008

These are the characteristics and key findings for a Cochrane review published in this issue of EBCH, first published as Brazzelli M, Griffiths P. Behavioural and cognitive interventions with or without other treatments for the management of faecal incontinence in children. Cochrane Database of Systematic Reviews 2006, Issue 2. Art. No.: CD002240. DOI: 10.1002/14651858.CD002240.pub3.

Further information for this Cochrane review is available in this issue of EBCH in the accompanying EBCH Summary and Commentary articles. Copyright © 2008 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. The Cochrane Collaboration