bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Synthetic Equivalent of a Germanone Derivative
Authors: Bonnefille Eric , Mazières Stéphane , Bibal Christine , Saffon Nathalie , Gornitzka Heinz , Couret Claude 
Published: August 2008

AbstractReaction of two molar equivalents of 2,6‐bis(diisopropylaminomethyl)phenyllithium (ArLi) with tetramethoxygermane afforded the colourless crystalline dimethoxy bis[2,6‐bis(diisopropylaminomethyl)phenyl]germane Ar2Ge(OMe)2 (1) in good yield. Treatment of 1 with AgF/H2O led to the fluorohydroxy derivative Ar2Ge(F)OH (2), which was characterized, among other techniques, by single‐crystal structure analysis. The corresponding lithio compound Ar2Ge(F)OLi (3) obtained from 2 by reaction with tBuLi behaves as a synthetic equivalent of the heavier analogue of ketone[Ar2Ge=O, 5]. Germanone 5 could not be isolated even at low temperature due to the impossibility of dissociating it from LiF. Treatment of 3 with various reactants on the basis of the known reactivity of ketones led to the expected products. The reaction of 3 with H2O led, as expected, quantitatively to the germanium gem‐diol Ar2Ge(OH)2 (6) as colourless crystals. Such gem‐diols are scarce compounds and only a few are structurally known; in our case, 6 is stabilized by a hydrogen linkage between the hydrogen atoms of the alcohol functionalities and the nitrogen atoms. Other trapping reactions of 3 were investigated with tBuLi and methanol, and the corresponding germanols Ar2Ge(tBu)OH (7) and Ar2Ge(OMe)OH (8) were isolated after hydrolysis in good yields. Attempts to eliminate LiF from 3 by using the chelating agent 1,4,7,10‐tetraoxacyclododecane (12‐crown‐4) allowed us to isolate lithio complex 9. Generation of germanones from fluorohydroxygermanes and their lithio derivatives appears to be a new promising method. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
New polymers by copolymerization of olefins with bio oil components
Authors: Kaminsky Walter , Fernandez Mercia 
Published: August 2008

AbstractOleic acid methyl ester can be converted by metathesis reaction in the presence of ethene into 1‐decene and 9‐decenoic acid methyl ester. Both components are suitable comonomers for the synthesis of polyolefin specialties by copolymerization with ethene or propene. For this copolymerization, metallocene/methylaluminoxane catalyst or other single‐site catalysts are more active than classical Ziegler‐Natta catalysts because they insert higher amounts of longer‐chain α‐olefins or olefins with polar groups. The microstructure of these copolymers can be tailored in a great variety using metallocene complexes with different symmetries.
Oxidative stability of sunflower oil bodies
Authors: Fisk Ian D. , White Daniel A. , Lad Mitaben , Gray David A. 
Published: August 2008

AbstractThis study investigates the oxidative stability of sunflower oil body suspensions (10 wt‐% lipid). Two washed suspensions of oil bodies were evaluated over 8 days at three temperatures (5, 25 and 45 °C) against three comparable sunflower oil emulsions stabilized with dodecyltrimethylammonium bromide (DTAB), polyoxyethylene‐sorbitan monolaurate (Tween 20) and sodium dodecyl sulfate (SDS) (17 mM). The development of oxidation was monitored by measuring the presence of lipid hydroperoxides and the formation of hexanal. Lipid hydroperoxide concentrations in the DTAB, SDS and Tween 20 emulsions were consistently higher than in the oil body suspensions; furthermore, hexanal formation was not detected in the oil body emulsions, whereas hexanal was present in the headspace of the formulated emulsions. The reasons for the extended resistance to oxidation of the oil body suspensions are hypothesized to be due to the presence of residual seed proteins in the continuous phase and the presence of a strongly stabilized lipid‐water interface.
Studies of substrate specificities of lipases from different sources
Authors: Song Xin , Qi Xiaoyu , Hao Bin , Qu Yinbo 
Published: August 2008

AbstractAlthough lipases are widely applied in a wide variety of reactions, available information on the factors that are responsible for the substrate specificities of lipases from different sources is scarce. In this paper, nine lipase‐producing microorganism strains were isolated from oil‐containing samples. The properties of these enzymes, including pH optima, temperature optima, thermal stability, and pH stability, vary significantly with the different sources from which these lipases were isolated. The substrate specificities of the nine lipases, including fatty acid and positional specificities, were also studied. The fatty acid specificities of the nine lipases were observably different toward 15 substrates with different carbon chain lengths, different saturation degrees and different side chains. The lipases from S3 Penicillium citrinum (PCL), MJ1 Aspergillus niger (ANL), MJ2 Aspergillus oryzae (AOL), YM Bacillus coughing (BCL), S9 Geotrichum candidum (GCL), and S11 Candida lypolytica (CLL) showed the strongest specificities to short‐chain esters, and the other lipases showed strong selectivity for medium‐ or long‐chain and branched esters. The positional specificities were examined by analyzing the hydrolytic products of triolein catalyzed by the nine lipases, using TLC. The lipases can be mainly classified into two groups by their specificities for the ester bond at position 2 of triglycerides; one group can selectively hydrolyze the ester bond at position 2 of the triglycerides, the other group cannot. All these nine lipases were divided into four groups by hierarchical clustering analysis on the basis of the results of fatty acid and positional specificities.
Synthesis of Alkaloids of Galipea officinalis by Alkylation of an α‐Amino Nitrile
Authors: Shahane Saurabh , Louafi Fadila , Moreau Julie , Hurvois Jean‐Pierre , Renaud Jean‐Luc , van de Weghe Pierre , Roisnel Thierry 
Published: August 2008

AbstractA new synthetic approach directed towards the synthesis of naturally occurring 2‐alkyl‐tetrahydroquinolines is described. The C–C bonds in the α position relative to the nitrogen atom were formed by the reversal of the polarity of the C=N bond of α‐amino nitrile 6, which was prepared electrochemically from 1‐(phenylethyl)‐tetrahydroquinoline. A NaBH4‐mediated reductive decyanation process furnished benzylic amines 16a–d as mixtures of diastereomers (50–60 % de). The catalytic hydrogenolysis of these amines was performed in the presence of Pearlman's catalyst to give the tetrahydroquinolines 17a–d in yields ranging from 70 % to 95 %. Methylation of the free nitrogen atom afforded the title compounds 1–4 in 70–90 % yields.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Electroanalytical Determination of Promethazine Hydrochloride in Pharmaceutical Formulations on Highly Boron‐Doped Diamond Electrodes Using Square‐Wave Adsorptive Voltammetry
Authors: Ribeiro Francisco Wirley P. , Cardoso Amanda S. , Portela Rafael R. , Lima Janete E. S. , Machado Sergio A. S. , de Lima‐Neto Pedro , De Souza Djenaine , Correia Adriana N. 
Published: August 2008

AbstractThe electrochemical oxidation of promethazine hydrochloride was made on highly boron‐doped diamond electrodes. Cyclic voltammetry experiments showed that the oxidation mechanisms involved the formation of an adsorbed product that is more readily oxidized, producing a new peak with lower potential values whose intensity can be increased by applying the accumulation potential for given times. The parameters were optimized and the highest current intensities were obtained by applying +0.78 V for 30 seconds. The square‐wave adsorptive voltammetry results obtained in BR buffer showed two well‐defined peaks, dependent on the pH and on the voltammetric parameters. The best responses were obtained at pH 4.0, frequency of 50 s−1, step of 2 mV, and amplitude of 50 mV. Under these conditions, linear responses were obtained for concentrations from 5.96×10−7 to 4.76×10−6 mol L−1, and calculated detection limits of 2.66×10−8 mol L−1 (8.51 μg L−1) for peak 1 and of 4.61×10−8 mol L−1 (14.77 μg L−1) for peak 2. The precision and accuracy were evaluated by repeatability and reproducibility experiments, which yielded values of less than 5.00% for both voltammetric peaks. The applicability of this procedure was tested on commercial formulations of promethazine hydrochloride by observing the stability, specificity, recovery and precision of the procedure in complex samples. All results obtained were compared to recommended procedure by British Pharmacopeia. The voltammetric results indicate that the proposed procedure is stable and sensitive, with good reproducibility even when the accumulation steps involve short times. It is therefore very suitable for the development of the electroanalytical procedure, providing adequate sensitivity and a reliable method.
Fabrication of a Sensitive Impedance Biosensor of DNA Hybridization Based on Gold Nanoparticles Modified Gold Electrode
Authors: Zhang Keying , Ma Haiyan , Zhang Liping , Zhang Yuzhong 
Published: August 2008

AbstractIn this work, we report on the preparation of a simple, sensitive DNA impedance sensor. Firstly gold nanoparticles were electrodeposited on the surface of a gold electrode, and then probe DNA was immobilized on the surface of gold nanoparticles through a 5′‐thiol‐linker. Electrochemical impedance spectroscopy (EIS) was used to investigate probe DNA immobilization and hybridization. Compared to the bare gold electrode, the gold nanoparticles modified electrode could improve the density of probe DNA attachment and the sensitivity of DNA sensor greatly. The difference of electron transfer resistance (ΔRet) was linear with the logarithm of complementary oligonucleotides sequence concentrations in the range of 2.0×10−12 to 9.0×10−8 M, and the detection limit was 6.7×10−13 M. In addition, the DNA sensor showed a fairly good reproducibility and stability during repeated regeneration and hybridization cycles.
The Influence of the Electrodeposition Conditions on the Electroanalytical Performance of the Bismuth Film Electrode for Lead Determination
Authors: Nunes Luiza M. S. , Faria Ronaldo C. 
Published: August 2008

AbstractThe bismuth film is a great promise as a suitable material to replace the mercury electrodes due to its low toxicity and good cathodic potential range. This work studies the influence of the electrodeposition conditions in the morphology and electroanalytical performance of the bismuth film electrodeposited onto copper electrode. The bismuth films were obtained in nitric or hydrochloric acid solutions with and without the presence of sodium citrate. The films were characterized by field emission scanning electron microscopy (FE‐SEM) and scanning electron microscopy with energy dispersive X‐ray spectrometry (SEM‐EDX). The microscopic analysis of the bismuth film obtained in HCl solution with sodium citrate (BIFE‐Cit) showed more homogeneous structure with higher content of bismuth than the film obtained in HCl only (BiFE‐HCl). The BiFE‐Cit exhibited a better analytical performance for lead with good adherence to the copper substrate.
Development of a Creatinine Sensor Based on a Molecularly Imprinted Polymer‐Modified Sol‐Gel Film on Graphite Electrode
Authors: Patel Amit Kumar , Sharma Piyush Sindhu , Prasad Bhim Bali 
Published: August 2008

AbstractAn electrochemical creatinine sensor based on a molecularly imprinted polymer (MIP)‐modified sol‐gel film on graphite electrode was developed. The surface coating of MIP over sol‐gel was advantageous to obtain a porous film with outwardly exposed MIP cavities for unhindered selective rebinding of creatinine from aqueous and biological samples. A fast differential pulse, cathodic stripping voltammetric response of creatinine can be obtained after being preanodized the sensor in neutral medium containing appropriate amount of creatinine at +1.8 V versus SCE for 120 s. A linear response over creatinine concentration in the range of 1.23 to 100 μg mL−1 was exhibited with a detection limit of 0.37 μg mL−1 (S/N=3).
Study on the Indirect Electrochemical Detection of Ammonium Ion with In Situ Electrogenerated Hypobromous Acid
Authors: Takahashi Miki , Nakamura Kenta , Jin Jiye 
Published: August 2008

AbstractThe electrochemical oxidation of bromide in the presence of ammonium ion (NH$\rm{ {_{4}^{+}}}$) was studied by cyclic voltammetry and UV‐vis spectroscopy. The experimental results suggested that the anodically generated bromine (Br2) would be hydrolyzed to hypobromous acid (HBrO) at the pH range of 5–7 and was further disproportionate to hypobromite anion (BrO−) when pH was larger than 7. Both HBrO and BrO− were confirmed to be participated in the following homogeneous chemical reaction with the coexisted ammonium ion. However, HBrO is electroactive whereas BrO‐ is electroinactive at carbon electrode. Based upon the reaction of HBrO with NH$\rm{ {_{4}^{+}}}$, an indirect electrochemical method was proposed for determination of NH$\rm{ {_{4}^{+}}}$ with dual‐electrode configuration in phosphate buffer solution (pH 7), where HBrO was produced at a generator electrode and the excess HBrO was subsequently detected at a collector electrode after a reaction with NH$\rm{ {_{4}^{+}}}$ in a batch solution or in a micro flow injection analytical (micro‐FIA) system by using an interdigitated array (IDA) Pt microelectrode and a carbon film ring‐disk electrode (CFRDE), respectively. The decreasing of reduction current at the collector electrode was proportional to the concentration NH$\rm{ {_{4}^{+}}}$ in both systems, with the detection limit below 3.0 μM. This approach shows the advantage of highly selectivity even in presence of a large amount of coexisted cations, and was successfully applied for the determination of NH$\rm{ {_{4}^{+}}}$ in environmental water samples.
Clonal expansions of 6‐thioguanine resistant T lymphocytes in the blood and tumor of melanoma patients
Authors: Albertini Mark R. , Macklin Michael D. , Zuleger Cindy L. , Newton Michael A. , Judice Stephen A. , Albertini Richard J. 
Published: August 2008

AbstractThe identification of specific lymphocyte populations that mediate tumor immune responses is required for elucidating the mechanisms underlying these responses and facilitating therapeutic interventions in humans with cancer. To this end, mutant hypoxanthine‐guanine phosphoribosyltransferase (HPRT) deficient (HPRT‐) T‐cells were used as probes to detect T‐cell clonal amplifications and trafficking in vivo in patients with advanced melanoma. Mutant T‐cells from peripheral blood were obtained as clonal isolates or in mass cultures in the presence of 6‐thioguanine (TG) selection and from tumor‐bearing lymph nodes (LNs) or metastatic melanoma tissues by TG‐selected mass cultures. Nonmutant (wild‐type) cells were obtained from all sites by analogous means, but without TG selection. cDNA sequences of the T‐cell receptor (TCR) beta chains (TCR‐β), determined directly (clonal isolates) or following insertion into plasmids (mass cultures), were used as unambiguous biomarkers of in vivo clonality of mature T‐cell clones. Clonal amplifications, identified as repetitive TCR‐β V‐region, complementarity determining region 3 (CDR3), and J‐region gene sequences, were demonstrated at all sites studied, that is, peripheral blood, LNs, and metastatic tumors. Amplifications were significantly enriched among the mutant compared with the wild‐type T‐cell fractions. Importantly, T‐cell trafficking was manifested by identical TCR‐β cDNA sequences, including the hypervariable CDR3 motifs, being found in both blood and tissues in individual patients. The findings described herein indicate that the mutant T‐cell fractions from melanoma patients are enriched for proliferating T‐cells that infiltrate the tumor, making them candidates for investigations of potentially protective immunological responses. Environ. Mol. Mutagen., 2008. Published 2008 Wiley‐Liss, Inc.
Antimicrobial effect of vapours of terpineol, (R)‐(–)‐linalool, carvacrol, (S)‐(–)‐perillaldehyde and 1,8‐cineole on airborne microbes using a room diffuser
Authors: Krist Sabine , Sato Kei , Glasl Sabine , Hoeferl Martina , Saukel Johannes 
Published: August 2008

AbstractIn this study the antimicrobial activities of five volatiles, which represent main compounds of several essential oils, were tested. Terpineol, (R)‐(–)‐linalool, carvacrol, (S)‐(–)‐perillaldehyde and 1,8‐cineole were evaluated for their influence on airborne microbes when vaporized with a room diffuser. In the present investigation terpineol and (S)‐(–)‐perillaldehyde showed the highest antimicrobial activities. The average reduction of the germ count was 59.4% and 42.3%, respectively, after 5 h of spreading in a testing room. Carvacrol (average germ reduction 37.5%) and (R)‐(–)‐linalool (29.7%) showed lower results. For 1,8‐cineole only, no unambiguous antimicrobial effect was detectable. It has to be considered that the amounts of vapour spread during 5 h of testing time were different, depending on the volatility of the scent used. Nevertheless, four of the investigated volatiles showed satisfying antimicrobial action against airborne microbes. Copyright © 2008 John Wiley & Sons, Ltd.
Correlation of environmental and cultural chronology in New Caledonia
Authors: Carson Mike T. 
Published: August 2008

AbstractA case study in New Caledonia explores the changes in the natural and cultural setting at the end of the Lapita period in the first millennium B.C. After the mid‐Holocene highstand, sea level fell about 1.5 m, thereby enlarging coastal plains, altering previous mangrove and marshy settings, and transforming nearshore marine environments. Many of these changes occurred gradually over several centuries, but the termination of finely decorated Lapita pottery coincided with the first signs of loss of coastal habitat optimal for marine‐based horticulturalists in the first millennium B.C. Organized village compounds and extensively cultivated landscapes emerged much later, in the first millennium A.D. The results suggest that, although the Lapita phenomenon represents the founding ancestry of Oceanic societies, it also represents the end of an era and way of life that eventually could not be maintained in a changing world. © 2008 Wiley Periodicals, Inc.
A micromorphological analysis of stratigraphic integrity and site formation at Cactus Hill, an Early Paleoindian and hypothesized pre‐Clovis occupation in south‐central Virginia, USA
Authors: Macphail1 Richard I. , McAvoy Joseph M. 
Published: August 2008

AbstractTwenty thin sections were studied from Cactus Hill, a ca. 20 ka stratified sand dune site in Virginia, USA, with a Clovis and hypothesized pre‐Clovis component. The high‐resolution soil micromorphology investigation focused on testing the integrity of Clovis and pre‐Clovis stratigraphy from one location where there is a high density of artifacts. Site formation processes were dominated by eolian (dune) sand formation. There was also ephemeral topsoil development and associated occupation, along with their penecontemporaneous disturbance and dispersal by scavenging animals (assumed) and localized down‐working by small invertebrate mesofauna (as evidenced by aggregates of fine phytolith‐rich humic soil and fine soil‐coated charcoal fragments). Partial erosion of these occupation soils (deflation?) was followed by successive sand burial. Post‐depositional processes affecting these sand‐buried occupations involved only small‐scale bioturbation and overprinting of clay lamellae, suggesting site stratigraphy has been stable for a long time. Soil micromorphological analysis has defined a difference between occupational units (pre‐Clovis and Clovis) and sterile units found between these units as well as above and below. In summary, according to this analysis, the site appears intact with only minor disturbances affecting the long‐term integrity of the stratigraphy. © 2008 Wiley Periodicals, Inc.
The effects of cigarette smoking and abstinence on auditory verbal learning
Authors: Soar Kirstie , Dawkins Lynne , Begum Husna , Parrott Andrew C. 
Published: August 2008

AbstractSmoking has been associated with both enhanced and impaired cognitive performance; across a variety of domains, but there is limited evidence demonstrating the effects on verbal learning. The current study assessed the effect of smoking and abstinence on verbal learning, immediate memory and retention using the Auditory Verbal Learning Test (AVLT). Three groups: 20 smokers, 20 abstaining smokers and 20 non‐smoking adults were assessed on the AVLT on two occasions. At session one, abstaining smokers refrained from smoking for 12 h (pre‐cigarette), whilst smokers had continued to smoke to satiety. Session two commenced after a 15‐min break when both smoking groups were instructed to smoke a cigarette, followed by administration of the second version of the AVLT (post‐cigarette). Abstaining smokers showed significant deficits in learning compared to smokers during the pre‐cigarette session. Following re‐initiation of smoking in the abstaining smokers, these learning decrements were no longer evident. There were trends towards significant group findings in immediate memory and retention during the pre‐cigarette session, which again were no longer evident in the post‐cigarette session. These findings provide further evidence that smoking abstinence affects verbal learning and furthermore smoking simply restores cognitive performance to pre‐abstinence levels. Copyright © 2008 John Wiley & Sons, Ltd.
Variation in lung cancer risk by smoky coal subtype in Xuanwei, China
Authors: Lan Qing , He Xingzhou , Shen Min , Tian Linwei , Liu Larry Z. , Lai Hong , Chen Wei , Berndt Sonja I. , Hosgood Howard Dean , Lee Kyoung‐Mu , Zheng Tongzhang , Blair Aaron , Chapman Robert S. 
Published: August 2008

AbstractLung cancer rates in Xuanwei County have been among the highest in China for both males and females and have been causally associated with exposure to indoor smoky (bituminous) coal emissions that contain very high levels of polycyclic aromatic hydrocarbons. There are numerous coal mines across the County. Although lung cancer risk is strongly associated with the use of smoky coal as a whole, variation in risk by smoky coal subtype has not been characterized as yet. We conducted a population‐based case–control study of 498 lung cancer cases and 498 controls, individually matched to case subjects on age (±2 years) and sex to examine risk by coal subtype. Odds ratios (ORs) and 95% confidence intervals (CIs) for coal subtype were calculated by conditional logistic regression, adjusting for potential confounders. Overall, smoky coal use was positively and statistically significantly associated with lung cancer risk, when compared with the use of smokeless coal or wood (OR = 7.7, 95% CI = 4.5–13.3). Furthermore, there was a marked heterogeneity in risk estimates for specific subtypes of smoky coal (test for heterogeneity: p = 5.17 × 10−10). Estimates were highest for coal of the Laibin (OR = 24.8, 95% CI = 12.4–49.6) and Longtan (OR = 11.6, 95% CI = 5.0–27.2) coal types and lower for coal from other subtypes. These findings strongly suggest that in Xuanwei and elsewhere, the carcinogenic potential of coal combustion products can exhibit substantial local variation by specific coal source. Published 2008 Wiley‐Liss, Inc.