bluuebunny/crossref_metadata_2025_split huggingface dataset:
Arsenic‐containing ribofuranosides and dimethylarsinic acid in green seaweed, Codium fragile
Authors: Jin Kazuo , Hayashi Takaaki , Shibata Yasuyuki , Morita Masatoshi 
Published: January 2005

AbstractThree water‐soluble arsenic compounds were isolated from the green seaweed Codium fragile. These compounds were identified as 1‐glycerophosphoryl‐2‐hydroxy‐3‐[5′‐deoxy‐5′‐(dimethylarsinoyl)‐β‐ribofuranosyloxy]propane (1a), 1′ ‐(1,2‐dihydroxypropyl)‐5′ ‐deoxy‐5′ ‐(dimethylarsinoyl)‐β‐ribofuranoside (1b), and dimethylarsinic acid ((CH3)2AsOOH). The structures of these compounds were ascertained by 1H NMR spectroscopy. Compounds 1a and 1b accounted for 60 % and dimethylarsinic acid for 5% of the water‐soluble arsenic.
Ubiquity of arsenobetaine in marine animals and degradation of arsenobetaine by sedimentary micro‐organisms
Authors: Hanaoka Ken'Ichi , Yamamoto Hideki , Kawashima Keishiro , Tagawa Shoji , Kaise Toshikazu 
Published: January 2005

AbstractArsenic compounds were extracted with chloroform/methanol/water from tissues of marine animals (four carnivores, five herbivores, five plankton feeders). The extracts were purified by cation and anion exchange chromatography. Arsenobetaine [(CH3)3As+CH2COO−], dimethylarsinic acid [(CH3)2AsOOH], trimethylarsine oxide [(CH3)3AsO] and arsenite, arsenate, and methylarsonic acid [(CH3)AsO(OH)2] as a group with the same retention time were identified by high‐pressure liquid chromatography. Arsenic was determined in the collected fractions by graphite furnace atomic absorption spectrometry. Arsenobetaine found in all the animals was almost always the most abundant arsenic compound in the extracts. These results show that arsenobetaine is present in marine animals independently of their feeding habits and trophic levels.Arsenobetaine‐containing growth media (ZoBell 2216E; solution of inorganic salts) were mixed with coastal marine sediments as the source of microorganisms. Arsenobetaine was converted in both media to trimethylarsine oxide and trimethylarsine oxide was converted to arsenite, arsenate or methylarsonic acid but not to dimethylarsinic acid. The conversion rates in the inorganic medium were faster than in the ZoBell medium. Two dominant bacterial strains isolated from the inorganic medium and identified as members of the Vibro–Aeromonas group were incapable of degrading arsenobetaine.
Bioaccumulation of alkyllead compounds from water and from contaminated sediments by mussels
Authors: Chau Y K , Wong P T S , Bengert G A , Wasslen J 
Published: January 2005

AbstractThe bioconcentration of alkyllead compounds from water and from contaminated sediments by freshwater mussels (Elliptio complanata) has been investigated. Higher levels of trimethyllead than triethyllead species are accumulated for the same exposure period. In‐vivo transformation of the trialkyllead species by a series of dealkylation reactions giving dialkyllead and inorganic lead(II) species appears to take place. Rates of accumulation are higher for the more contaminated sediments.
Methylation of tin(II) by methyl iodide in porewater
Authors: Lee Dong Sup , Weber James H 
Published: January 2005

AbstractThe methylation of tin(II) chloride by methyl iodide in porewater and formation of monomethyltin as the only methyltin product are described. A factorial experiment tested the effects of concentrations of tin(II), methyl iodide, and oxygen on monomethyltin yields. The experiments gave 0.18 to 12.8 % yield. Analysis of variance (ANOVA) calculations showed that all three variables were significant at the 95 % level. Comparison of yields in aqueous 23 g kg−1 sodium chloride solutions to those in porewater and to those containing fulvic acid, salicylic acid, and EDTA showed that only fulvic acid significantly reduced yields. Reasons for this observation are discussed and the findings in the model system are related to methylation of tin compounds in sediments.
Trace speciation by HPLCGF AA for tin‐ and leadbearing organometallic compounds, with signal increases induced by transition‐metal ions
Authors: Parks E J , Brinckman F E , Jewett K L , Blair W R , Weiss C S 
Published: January 2005

AbstractHigh‐performance liquid chromatography coupled with graphite furnace atomic absorption spectroscopy (HPLCGF AA) gives element‐specific detection of environmental samples containing trace amounts of organotin or organolead species. The direct GF AA of organotin and organolead species is subject to errors arising primarily from loss of analyte prior to atomization, probably through the formation of refractory carbides and of compounds or complexes that are volatile at low temperatures. Examples abound in the literature of signal suppression in the GF AA of organometallic species in environmental samples, and several furnace tube modifications have been developed to overcome this suppression. Here, the analyte and a modifier are co‐pipetted into a conventional furnace tube, from either a solution of analyte or an HPLC effluent. Oxides of transition metals (e.g. chromium, manganese, or tungsten) are shown to enhance both tin and lead signals, whereas chlorides do not, suggesting the low‐temperature formation of relatively involatile metal oxides or volatile metal chlorides, respectively. In the absence of modifier, GF AA signal intensities decrease consecutively for equal quantities of mono‐, di‐, tri‐ and tetra‐butyltin species, but are nearly equal for the first three in the presence of complexing dichromate (Cr2O72−). The lesser signal increase for tetrabutyltin indicates a dissimilar low‐temperature complexation chemistry for the fully ligated neutral organometal to that for the ligated ions. similar results are demonstrated in post‐column addition of a matrix modifier to effluent containing either organotin or organolead species.
Kinetics and mechanism of nucleophilic addition at the bridging vinyl ligand of the cluster [HOs3 (η2‐CHCH2) (CO)10]
Authors: Kane‐Maguire Leon A P , Ghazy Tahany 
Published: January 2005

AbstractKinetic and spectroscopic studies are reported for the addition of a range of neutral phosphorus and nitrogen nucleophiles to the bridging η2‐vinyl ligand of the cluster [HOs3(η2‐CHCH2)(CO)10]. With PPh3, the reaction is reversible, and the rate law, kobs = k1[Nuc] + k−1, is observed. This rate law is consistent with direct bimolecular addition (k1) of PPh3 to the η2‐vinyl ligand. With more basic triarylphosphine nucleophiles, the simple expression, kobs = k1[PR3], is obeyed. The second‐order rate constant, k1, varies markedly with the phosphine basicity. For the series P(4‐XC6H4)3, a linear Brönsted plot of log k1 vs pKa is obtained with a slope α of 0.46. The reversible addition of cyclohexylamine to this cluster also obeys a two‐term rate law. Overall, nucleophilicity towards [HOs3(η2‐CHCH2)(CO)10] decreases in the order C6H11NH2 > P(4‐MeOC6H4)3 > P(4‐MeC6H4)3 > PPh3, which quantitatively parallels that previously found for the related mononuclear cation [CpFe(CO)2(η2‐CH2CH2)]+.
Reactivity and reaction pathways of electrochemically generated 17‐electron tricarbonyl steroid chromium cations
Authors: Bond Alan M , Mocellin Enrico , Pascual Cherrie B , Wedkanjana Panit , Jaouen Gérard , Top Siden 
Published: January 2005

AbstractElectrochemical oxidation of α‐ and β‐diastereomers of a range of steroid hormone receptor marker chromium tricarbonyl complexes, (steroid)Cr(CO)3, have been examined at platinum electrodes in dichloromethane. Data confirm the general nature of previously published conclusions on the oxidation of (arene)Cr(CO)3 complexes (arene = benzene or steroid). That is, with 0.1 M Bu4NPF6 as the electrolyte, and in the absence of nucleophiles, a reversible oneelectron process, (steroid)Cr(CO)3 ⇌ [(steroid)Cr(CO)3]+ + e−, is observed, followed by an irreversible one‐electron process at considerably more positive potentials. The reversible half‐wave potentials (approximately E°‐values) calculated for the [(steroid)Cr(CO)3]+/(steroid)Cr(CO)3 redox couple are shown to be dependent on whether the α‐ or β‐diastereomer is oxidized. Similarly the rate of nucleophilic attack on the 17‐electron cation [(steroid)Cr(CO)3]+ by nucleophiles such as ClO, PPh3 and bis(diphenylphosphine)methane confirms a previous observation that the stereochemistry of this class of compound is important with respect to redox, kinetic and hormone receptor properties. The nature of the electrochemical data obtained on the (arene)Cr(CO)3 complexes in the presence of nucleophiles suggests that reactions associated with the nucleophilic attack on the 17‐electron cations are complex and that a range of reaction pathways occur simultaneously. Electrochemical studies on the oxidation of (benzene)Cr(CO)2PPh3 and (oestradiol)Cr(CO)2PPh3 confirm some aspects of the proposed mechanisms, although it is clear that a great deal still has to be learned concerning mechanistic aspects of nucleophilic attack on these 17‐electron complexes.
Comparative study of the biological activity of organosilicon and organogermanium compounds
Authors: Lukevics E , Ignatovich L 
Published: January 2005

AbstractThe literature data and the results of our own investigations on the comparative study of the biological activity of isostructural organogermanium and organosilicon compounds have been summarized. It has been shown that the series of organogermanium and organosilicon compounds is more active than the carbon analogues, the majority of organogermanium compounds are less toxic than the sila analogues, the biological activity of the compounds under study appears to be similar but can dramatically differ in the degree of activity, and, moreover, in some particular cases sila and germa analogues exhibit the opposite biological effects.
Chemical methylation of germanium(II) in model aqueous solutions
Authors: Mayer H P , Rapsomanikis S 
Published: January 2005

AbstractInorganic germanium(II) in micromolar concentrations was reacted with methyl iodide (CH3I) and methylcobalamin (CH3‐CoB12) at various pH values and with different salt matrices. In all experiments monomethylgermanium was the only product. The reaction with CH3‐CoB12 at pH 1 yielded approximately 1.3% of the added germanium, whereas no methylation occurred at pH 7. Reaction yields with CH3I were lowest at pH 1 in 0.1 mol dm−3 KCl (1.6%) and highest at pH 7.6 in artificial seawater (6%). For the reaction of CH3−CoB12 with germanium(II) a free‐radical mechanism is assumed, whereas methylation by CH3I is most likely an oxidative addition mechanism.
The use of liposomes in predicting the biological mobility of arsenic compounds
Authors: Cullen William R , Nelson John 
Published: January 2005

AbstractEfflux studies of radio‐labelled methylarsonic acid (MMA) and dimethylarsinic acid (DMA) encapsulated in liposomes afford the following permeability values for the two arsenicals: 1.4 × 10−13 cm s−1 and 4.5 × 10−11 cm s−1 for MMA and DMA, respectively. These data are compared with the octanol/water partition coefficients which are 7.4 × 10−3 and 8.4 × 10−3 for MMA and DMA, respectively.
Inorganic arsenic: A dangerous enigma for mankind
Authors: Tsuda Toshihide , Babazono Akira , Ogawa Takanori , Hamada Hirohisa , Mino Yoshio , Aoyama Hideyasu , Kurumatani Norio , Nagira Tsuyoshi , Hotta Nobuyuki , Harada Masazumi , Inomata Shigemi 
Published: January 2005

AbstractHuman being have been using inorganic arsenic for a long time. Many reports on arsenic poisoning have been published: eg case reports, examination reports, post mortem reports, and epidemiological studies. Several aspects and features of arsenic poisoning are discussed in this report. Methods of inferring arsenic‐related disease, disease classification according to acute or chronic criteria, exposure route, interaction, confounding factors, and the oxidation state of arsenic are all discussed. The effects of arsenic are classified into skin, respiratory system, gastrointestinal tract, liver, cardiovascular system, nervous system, and bone marrow effects. Carcinogenicity is an important chronic effect of arsenic poisoning, so special attention is paid to it in this review. In Japan, there have been many incidents of arsenic poisoning. In this review, we often use data from these cases, such as the Morinaga powdered‐milk poisoning case, the Ube soy‐sauce poisoning case, the Toroku mine incident, and the Nakajo well‐water poisoning case. We emphasize here the necessity of planning follow‐up studies and total health care for patients exposed to arsenic.
Biomethylation of arsenic and its excretion by the alga Chlorella vulgaris
Authors: Maeda Shigeru , Kusadome Katsuhiro , Arima Hiroyuki , Ohki Akira , Naka Kensuke 
Published: January 2005

AbstractExperimental results in this paper lead to the following conclusions. (1) Cell homogenates of Chlorella vulgaris adsorbed the inorganic arsenic compound Na2HAsO4 but no methylation of the arsenic occurred in vitro. (2) A small part of the arsenic bioaccumulated by C. vulgaris was methylated in vivo. The quantity of arsenic methylated in the cell increased with an increase of arsenic concentration in the medium. (3) When the arsenic‐accumulating cells were transferred into arsenic‐free media, the arsenic was excreted and the relative quantity of the methylated arsenic in the excrement was larger than that in the cell. (4) In the growth phase of C. vulgaris, a small fraction of the arsenic accumulated in the cell was first transformed to monomethyl and dimethyl‐arsenic compounds during the early exponential phase, and after a short time a fraction was transformed to trimethylarsenic species.
Use of organometallic chemistry for hydrotreatment catalyst development
Authors: Hirschon A S , Wilson R B 
Published: January 2005

AbstractThis paper describes our use of organometallic chemistry to develop enhanced hydrotreatment catalysts. The approach involves (1) identifying the most active catalytic metals, (2) choosing precursors that will be easily activated into these materials under mild conditions, and (3) then increasing the surface area to provide a highly active catalyst. We describe our efforts in studying hydrodenitrogenation (HDN) reactions, including homogeneous reaction chemistry of the CN bond, development of enhanced HDN catalysts for coal liquids, and some applications of organometallic chemistry towards coal liquefaction.
Sulfided heterogeneous, bimetallic Ru/Mo catalysts derived from mixtures of Ru3(CO)12 (or RuCl3) and a molybdenum heteropolyanion: The reactions of ethanol with tetrahydroquinoline
Authors: Koo Sang‐Man , Ryan Dan , Laine Richard M. 
Published: January 2005

AbstractEfforts have been made to develop Ru/Mo bimetallic catalyst systems for hydrodenitrogenation (HDN) of tetrahydroquinoline (THQ). In the course of these studies, it was discovered that in ethanol, under hydrogen and in the presence of carbon disulfide (CS2), precatalyst solutions containing ruthenium [as Ru3(CO)12 or RuCl3] and molybdenum [as the H3PMo12O40 heteropolyanion (HPA)] decompose to form bimetallic, sulfided particles. Particle diameters run from 0.1 to 5μm depending on the rate of stirring. Catalyst particles with sizes ranging from 0.1 to 1μm can be prepared reproducibly. BET‐measured surface areas for these size particles ranged from 2 to 20m2 g−1. These sulfided particles were found to catalyze, at temperatures of 200–250°C and hydrogen pressures of 200–1000 psig (1.4–6.9 MPa) hydrogen, the N‐ethylation of THQ to form N‐ethyltetrahydroquinoline (N‐Et‐THQ), rather than the formation of propylcyclohexane or propylbenzene, reaction products expected for HDN of THQ. Monometallic heterogeneous catalysts prepared from the individual precatalyst complexes, under identical conditions, show minimal activity for N‐ethylation by comparison with the bimetallic catalyst.In the absence of hydrogen, the reaction proceeds so that THQ is converted to quinoline, N‐Et‐THQ, N‐C4H9‐THQ and N‐C6H13‐THQ. The latter products appear to arise via acetaldehyde, formed as an intermediate by dehydrogenation of ethanol. Acetaldehyde either condenses with THQ to form N‐Et‐THQ, or self‐condenses (aldol condensation) prior to reaction with THQ, thereby giving higher‐homolog alkylation products.
The use of sulfide cluster‐derived catalysts to understand the promotional effect in hydrotreatment catalysis
Authors: Brenner J R , Carvill B T , Thompson L T 
Published: January 2005

AbstractSulfide cluster‐derived ensembles are promising models of the active sites in commercial hydrotreatment catalysts. A series of sulfide clusters were adsorbed intact onto high‐surface‐area γ‐alumina, magnesium oxide and activated carbon supports, then pretreated to produce highly dispersed catalytic ensembles with sizes similar to those of their precursor clusters. The activities of the bimetallic cluster‐derived catalysts were significantly higher than those of the monometallic catalysts. We took this as evidence that direct interactions between molybdenum and the promoter element cause the promotional effect observed in commercial hydrotreatment catalysts. The hydrodesulfurization and hydrodenitrogenation activities correlated with the extent of molybdenum reduction. Our results suggested that the active sites in promoted hydrotreatment catalysts are centered on molecular‐scale ensembles containing molybdenum, sulfur and the promoter element.
Structural study of self‐assembled monolayers of ferrocenylalkanethiols on gold by angleresolved X‐ray photoelectron spectroscopy
Authors: Shogen Satoshi , Kawasaki Masahiro , Kondo Toshihiro , Sato Yukari , Uosaki Kohei 
Published: January 2005

AbstractAn angle‐resolved X‐ray photoelectron spectroscopic study has been performed on structures of self‐assembling systems, viz ferrocenylthiols on a gold (111) crystal. The angular dependence of the intensities of photoemission reveals that ferrocenyl groups are on the outermost layer, separated from the gold substrate by hydrocarbon chains of the thiol groups.
Organotin(IV) derivatives of mercaptosuccinic and thiodiacetic acids
Authors: Sandhu G K , Sharma N 
Published: January 2005

AbstractDi‐ and tri‐organotin(IV) complexes of general formula R2SnAH, (R3Sn)2AH, R2SnB, (R3Sn)2B (A=dianion of mercaptosuccinic acid; B=dianion of thiodiacetic acid; R=Me, Et, nPr, nBu, nOct in R2Sn and nBu in R3Sn) have been synthesized and characterized by elemental analysis, IR and 1H and 13C NMR spectroscopy. These data support the preferential binding of sulphur over carboxylate by tin(IV) in R2SnAH and (R3Sn)2AH. R2SnAH complexes are assigned pentacoordinated bridged polymeric trigonal bipyramidal geometry whereas (R3Sn)2AH complexes are monomeric with trigonal bipyramidal geometry at tin arising from a bidentate carboxylate group at one tin atom and from weak bonding via Sn←OC at the other tin atom. In R2SnB and (R3Sn)2B, tin(IV) binds to two carboxylate groups in a unidentate and a bidentate manner respectively, resulting in tetracoordinated and pentacoordinated structures. Potential uses of these compounds are discussed.
Diorganotin(IV) complexes of indole 3‐acetic acid
Authors: Sandhu G K , Sharma N 
Published: January 2005

AbstractAlkyl derivatives of indole 3‐acetic acid (IAA) have been prepared and are suitable for investigating steric substituent effects on hormonal activity without major interference from electronic effects. Triorganotin(IV) derivatives of indole 3‐acetic acid and N‐methylindole 3‐acetic acid have been reported to act as insecticidal, fungicidal and bactericidal agents. Me3SnIAA is more active as a biocide than Cy3SnIAA. The activity of these two compounds may be due to the fact that four‐coordinated tin monomers or five‐coordinated tin polymers are often more active than chelated five‐coordinated tin species because these readily undergo hydrolysis to give R3Sn(H2O+)2 species. The ligand affects the rate of formation of the ligand‐free active organotin entity. Biocidal activity is expected from diorganotin(IV) pentacoordinated complexes of indole 3‐acetic acid in the present case due to (i) the activity of pentacoordinated organotin species, (ii) the presence of an—NH moiety in the complexes, which is an active site for binding. The NH moiety may be deprotonated and nitrogen may coordinate with metal ions present in the physiological systems and thus destroy the activity of enzymes.
Comparative study of microwave‐induced plasma atomic emission spectrometry and atomic fluorescence spectrometry as gas‐chromatographic detectors for the determination of methylmercury in biological samples
Authors: Lansens Patrick , Meuleman Carine , Laiño Carmela Casais , Baeyens Willy 
Published: January 2005

AbstractIn order to attain a lower detection limit with the HS GC MIP analytical method (Head‐Space Gas Chromatography with Microwave‐Induced Plasma detection) recently developed for the analysis of methylmercury in biological samples, the quarter‐wave Evenson‐type cavity used until now was replaced by a TM010 Beenakker‐type cavity, which was used with both argon and helium as carrier gas. With an argon plasma, an eightfold increase in detection limit was gained compared with the argon plasma sustained by the Evenson cavity, while only a four‐fold increase was gained with the helium plasma. In a second step of the study, the MIP detector was replaced by an AFS (atomic fluorescence) detector (CVAFS Model‐2, Brooks Rand Ltd, Seattle, USA). With this AFS detector a detection limit of 1 ng methyl mercury per g biological tissue could be reached; i.e. measurements were 40 times more sensitive than those using the Evenson cavity. This detector has some other advantages compared with MIP detection: it is less expensive and easier to manipulate, while the same precision and accuracy are obtained. The use of AFS as detector in the headspace gas chromatographic system is therefore an important improvement for the analysis of methyl‐mercury in biological samples.
From cyclotetrasilazane [(CH3)2SiNH]4 via crystalline silicon nitride imide Si2N2NH to α‐Si3N4
Authors: Schaible Sabine , Riedel Ralf , Werner Elisabeth , Klingebiel Uwe 
Published: January 2005

Abstractα‐Si3N4 is synthesized by an ammonia thermal synthesis using a cyclic oligosilazane, [(CH3)2SiNH]4, as the starting material. [(CH3)2SiNH]4 reacts in the presence of ammonia at 900°C and 80 MPa pressure to give silicon nitride imide (Si2N2NH). Subsequently, Si2N2NH is converted into α‐Si3N4 by thermal decomposition at 1500°C and 0.1 MPa nitrogen with the simultaneous loss of NH3.
Organotin(IV) complexes of dibasic tridentate Schiff bases containing ONO donor atoms
Authors: Gopinathan S , Degaonkar M P , Hundekar A M , Gopinathan C 
Published: January 2005

AbstractOrganotin(IV) Schiff base complexes of the type (L)SnR2 [where RCH3, C6H5 or CH2CH2CO2 CH3], (LH)Sn(C6H5)3 and (L)SnCl(CH2CH2CO2 CH3) [where LH22‐N‐salicylideneimino‐2‐methyl‐1‐propanol, derived from the condensation of salicylaldehyde and 2‐amino‐2‐methyl‐1‐propanol] have been prepared and characterized on the basis of their elemental analyses, IR, 1H, 13C and 119Sn NMR studies. In these mononuclear complexes the Schiff base acts either as a dianionic tridentate or as a monobasic bidentate moiety by coordinating through an alkoxy group, an azomethine nitrogen and a phenoxide ion to tin. Sulphur dioxide inserts in the tin–methyl/–phenyl bond in the above Schiff base complexes to give tin–O–sulphinates of formulae (L)RSn(SO2R) and (LH)(C6H5)2Sn(SO2C6H5).
2‐HC12CI9: A simple synthesis of PCB‐206
Authors: Humphries R E , Massey A G 
Published: January 2005

AbstractA one‐pot synthesis is described for polychlorobi‐phenyl number 206. Addition of C6Cl5Li to tetrachlorobenzyne gives 2‐LiC12Cl9, which undergoes Li/H exchange with C6Cl5H to form 2, 2′, 3, 3′, 4, 4′, 5, 5′, 6‐nonachlorobiphenyl