bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractA 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

AbstractA 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

AbstractDuring 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

AbstractAn 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

AbstractFour 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

AbstractA 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

AbstractPhenylacetyl 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

AbstractIn 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

AbstractThe 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

AbstractLamellidens 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

AbstractA 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

AbstractThe 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

AbstractLandfill 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

AbstractThe 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

AbstractCritics 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

AbstractIn 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

AbstractThe 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

AbstractManagement 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

Abstract4‐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.