bluuebunny/crossref_metadata_2025_split huggingface dataset:
Methylation of inorganic tin by decaying spartina alterniflora in estuarine water and by estuarine water
Authors: Falke Anne M. , Weber James H. 
Published: January 2005

AbstractMethyltin compounds (MeSn) which do not originate from man–made pollution are common in estuaries and particularly in salt marshes containing the marsh grass Spartina alterniflora. This study reports the results of experiments in which estuarine water containing S. alterniflora leaves is spiked with inorganic tin, and estuarine water alone is spiked with inorganic tin and MeSn. When decaying leaves are present, inorganic tin concentrations in the water decrease and there is a 10‐fold increase in inorganic tin concentration in the leaves. This biosorption follows pseudo–first–order kinetics. MeSn3+ and Me2Sn2+ occur occasionally in the water. The Me2Sn2+ concentration decreases with time and the Me3Sn2+ concentration increases with time in S. alterniflora leaves. The results of estuarine water amended with inorganic tin and MeSn in the absence of leaves are quite different. The overall inorganic tin concentration decreases significantly during the experiment, the MeSn3+ concentration is approximately constant, and concentrations of Me2Sn2+ and Me3Sn+ increase. This means that net methylation of inorganic tin has occurred. We conclude that decaying S. alterniflora is likely to be important in the cycling of tin in salt marshes.
Laser photodissociation of trimethylaluminum and trimethylindium on a quartz substrate: Laser–induced fluorescence study
Authors: Sato Akihiko , Kasatani Kazuo , Sato Hiroyasu 
Published: January 2005

AbstractLaser photodissociation of trimethylaluminum and trimethylindium at 248 nm on a quartz substrate was studied by detecting aluminum and indium atoms appearing as reaction intermediates by laser–induced fluorescence. Photodissociation occurred predominantly in the adsorbed state in the experimental conditions. Kinetic energy distributions of the atoms were measured and were simulated by Maxwell–Boltzmann distributions in order to discuss photodissociation mechanisms.
(η5‐Pentamethylcyclopentadienyl)trimethyltitanium as a precursor for the syndiospecific polymerization of styrene
Authors: Kucht Homa , Kucht Andreas , Rausch Marvin D. , Chien James C. W. 
Published: January 2005

AbstractAn equimolar mixture of Cp*Ti(CH3)3 (2) and Ph3C+[B(C6F5)4]− (1) forms a highly active and syndioselective catalyst for the polymerization of styrene, producing 96% syndiotactic polystyrene (PS) at an activity of 0.91 × 107 g PS (mol Ti)−1 (mol styrene)−1 h−1. Both activity and syndioselectivity can be increased using tri–isobutylaluminum (TIBA) to scavenge the system. ESR measurements indicate that the polymerization proceeds via titanium(IV) intermediates. Catalysts derived from 2/methylaluminoxane (MAO) as well as Cp*TiCl3/MAO also function as syndioselective styrene polymerization catalysts, but are less active than the ‘cationic’; system derived from 1 and 2.
Synthesis and characterization of diorganotin(IV) derivatives of 2‐mercaptopyridine and crystal structure of diphenyl pyridine‐2‐thiolatochlorotin(IV)
Authors: Schmiedgen Ralf , Huber Friedo , Preut Hans , Ruisi Giuseppe , Barbieri Renato 
Published: January 2005

AbstractDiorganotin(IV) derivatives of 2‐mercaptopyridine (HSPy), R2Sn(SPy)2, R2SnCl(SPy) (R = Me, iPr, nBu, tBu, Cy, Ph) and Cy2SnBr(SPy), were obtained from R2SnX2 (X = Cl, Br) and NaSPy.Ph2SnCl(SPy) crystals, as determined by singlecrystal X–ray diffraction, are monoclinic in the space group P21/n. Tin forms with the bidentate SPy ligand a four–membered chelate ring with a short NSnS bite angle of 64.8(1)° leading to a heavily distorted trigonal–bipyramidal environment about tin. Apical Cl–Sn–N angle = 156.1(1)° equatorial C–Sn–C angle = 121.9(2)°. From 119Sn Mössbauer and IR data, analogous structures are inferred for the other solid compounds R2SnX(SPy), and distorted octahedral molecular structures for the solid compounds R2Sn(SPy)2 with R in the trans position, and sulfur atoms and nitrogen–donor atoms each in cis positions. According to IR and 1H, 13C and 119Sn NMR data, the solid–state molecular structures are retained in chloroform solution.
Organosilicon polymers with alternating σ‐ and π‐conjugated systems
Authors: Yuan Chien–Hua , West Robert 
Published: January 2005

AbstractA series of organosilicon polymers containing polysilane and diethynylaryl units along the polymer backbone were synthesized and examined with respect to their optical absorptions. The results indicate that delocalization takes place through the σ–π conjugated system. Lengthening of π‐conjugation leads to lower excitation energies while nearly identical UV–vis spectra are observed with increased Si–Si chain length. Introducing a thiophene unit into the π‐system instead of a benzene unit leads to a bathochromic shift reflecting greater σ–π delocalization. The polymers undergo photodegradation, probably via cleavage of the Si–Si bonds, and thermal crosslinking by reaction at the C≡C triple bonds. When doped with iodine, these polymers become semiconducting with conductivity of the order of 10−4 S cm−1.
Synthesis, NMR spectra and chromatographic properties of five trimethylarsonioribosides
Authors: Francesconi Kevin A. , Edmonds John S. , Stick Robert V. 
Published: January 2005

AbstractFive trimethylarsonioribosides were prepared from naturally occurring and synthetic dimethylarsinylribosides (arsenosugars) by reducing them with 2,3‐dimercaptopropanol and quaternizing the resultant arsine with methyl iodide. The trimethylarsonioribosides prepared in this manner were the four novel compounds methyl 5‐deoxy‐5‐trimethylarsonio‐β‐D‐riboside (as the iodide), (2′R)‐2′, 3′‐dihydroxypropyl 5‐deoxy‐5‐trimethylarsonio‐β‐D‐riboside (as the formate), 3′‐[(2″, 3″ ‐dihydroxypropyl)hydroxyphosphinyloxy] ‐ 2′ ‐hydroxypropyl 5‐deoxy‐5‐trimethylarsonio‐β‐D‐riboside and 3‐(5′‐deoxy‐5′‐trimethylarsonio‐β‐D‐ribosyloxy)‐(2S)‐2‐hydro xypropanesulfonate, and the known (2′S)‐2′‐hydroxy‐3′‐(sulfooxy)propyl 5‐deoxy‐5‐trimethylarsonio‐β‐D‐riboside. They were synthesized to serve as standards for chromatographic analyses of arsenic compounds in marine samples and for investigations into the biotransformation of arsenic in marine organisms. NMR spectral and chromatographic data for the five trimethylarsonioribosides are presented and compared with those of their dimethylarsinyl analogues.
Working Methods Paper: Certification of methylmercury compounds concentration in marine sediment reference material, IAEA‐356
Authors: Horvat M. , Mandić V. , Liang L. , Bloom N. S. , Padberg S. , Lee Y.‐H. , Hintelmann H. , Benoit J. 
Published: January 2005

AbstractAn intercomparison exercise was organized between seven laboratories using various isolation procedures (extraction, distillation, ion‐exchange and alkaline digestion) and detection systems (CV AAS, cold vapour atomic absorption spectroscopy; CV AFS, cold vapour atomic fluorescence spectroscopy; GC, ECD, gas chromatography electron capture detector and HPLC with CV AFS detection) for determination of methylmercury compounds in sediment sample. All certification criteria were fulfilled and therefore the value for total concentration of methylmercury compounds was certified to be 5.46 ng g−1, with a 95% confidence interval from 4.07–5.84 ng g−1. The acceptable range, calculated as two times the confidence interval of the mean is therefore from 4.68–6.23 ng g−1. This is the first sediment reference material ever to be certified for concentration of methylmercury compounds. Comparison of the data obtained by various methodologies has shown that the most critical step is the isolation of methylmercury compounds from binding sites. Acid leaching only cannot release methylmercury compounds quantitatively. Total release of methylmercury compounds could only be achieved by alkaline digestion or distillation. This simple intercomparison exercise has shown that since large numbers of laboratories world‐wide are performing methylmercury compound analyses using various improved and specific separation methods and sensitive detection systems, certification of methylmercury compounds in different biological and environmental samples should not be a problem in the future.
Use of a chromium tricarbonyl complex in a diels–alder reaction: Improved preparation of angularly trifluoromethyl‐substituted tetrahydrophenanthrone
Authors: Bonnet‐Delpon Danièle , Lequeux Thierry , Gruselle Michel , Malezieux Bernard 
Published: January 2005

AbstractThe tricarbonyl complex prepared from 1‐trifluoromethyldihydronaphthalene and Cr(CO)3(NH3)3 undergoes Diels–Alder cycloaddition under high‐pressure conditions (15 kbar) to give after decomplexation by natural light and deprotection, the tetrahydrophenanthrone product in 65% yield. This new methodology allows the activation of unreactive styrenes in Diels–Alder cycloaddition.
Speciation of organolead compounds in air by GC–MS–SIM
Authors: Nerín Cristina , Pons Begoña 
Published: January 2005

AbstractA procedure for trapping tetraalkyl‐lead (TAL) compounds in air is described. The system consists of a solid cartridge containing a mixture (65:35, w/w) in series of Porapak and Tenax. A contaminated atmosphere with a known concentration of TAL was generated in the laboratory. This atmosphere was trapped in the solid cartridge. After passing synthetic air through the system, the cartridge was extracted with hexane in an ultrasonic bath. The organic extract was concentrated under nitrogen current and the compounds were analyzed by GC–MS–SIM.Each step of the process was studied independently. Losses of volatile compounds in the evaporation step, the storage of the cartridge over 45 days before the extraction step and the break‐through volumes have been established in order to achieve optimization of the whole process. The analytical conditions of the final quantification include a linear range between 1.32 pg and 50.10 ng for Et4Pb, and 5.30 pg and 51.40 ng for Me4Pb. The detection limits are 0.66 pg, 3.40 pg, 1.07 pg, 1.05 pg and 2.60 pg for Et4Pb, Et3MePb, Et2Me2Pb, EtMe3Pb and Me4Pb, respectively.
The performance of an analytical method for determination of tbt during a six‐year monitoring programme
Authors: Waldock M. J. , Waite M. E. 
Published: January 2005

AbstractTributyltin (TBT) concentrations have been measured in UK waters, shellfish and sediments during the period 1986–1992. The methodology was based on conversion of alkyltin compounds to hydrides following extraction, and then measurement by gas chromatography with flame photometric detection. The collection of a large set of data to assess changes in environmental concentrations of organotins required use of good analytical quality control procedures at a time when no reference materials were available. An analytical quality control (AQC) system based on in‐house quality control materials was devised and the performance of the method independently assessed by periodic participation in intercalibration exercises with other expert laboratories.
Biotransformation of butyltin compounds using pure strains of microorganisms
Authors: Errécalde Olivier , Astruc Michel , Maury Georges , Pinel Raoul 
Published: January 2005

AbstractThe debutylation of tributyltin chloride by several strains of fungi, yeasts and bacteria is described. Under standard conditions and with low initial concentration of substrate, significant biotic degradation of tributyltin (6–32%) was detected after five days at 28°C. Dibutyltin and monobutyltin were formed in all cases, with higher yields of the latter. Two microorganisms catalysed the transformation of monobutyltin to dimethyltin and trimethytin whereas all microorganisms were able to methylate inorganic tin(IV) to trimethyltin. Our results suggest that tributyltin biodegradation by microorganisms is generally possible, provided sufficiently low concentrations of substrate are used.
Acid extraction treatment of sediment samples for organotin speciation; occurrence of butyltin and phenyltin compounds on the cadiz coast, south‐west spain
Authors: Gomez‐ariza J. L. , Beltrán R. , Morales E. , Giraldez I. , Ruiz‐benitez M. 
Published: January 2005

AbstractA method is described for leaching of nanogram amounts of mono‐, di and tri‐butyltin compounds and mono‐, di‐ and tri‐phenyltin compounds from sediments. The procedure is based on soaking the sediments in a water–hydrogen bromide mixture (2:3) with magnetic stirring for 1 h followed by extraction with 0.02% (w/v) tropolone solution in pentane for 2 h. Organotins are determined by GF FPD after clean‐up through a Florisil column and derivatization by Grignard pentylation. The method has been applied to the study of water and sediments in different areas of south‐west Spain. Predominant species are butyltins, especially tributyltin (TBT), which has high values in waters and sediments of Puerto de Santa Maria and Cadiz Bay, as well as in sediments of the Sancti Petri Channel, which suggests a harmful action on biota. A direct relation has been found beween organotin levels and distance of potential focus determined by boating activities. In addition, the relative occurrence of dibutyltin (DBT) and monobutyltin (MBT) together with TBT has been noted, possibly as a result of a degractation process, and the influence of grain size of sediment and presence of organic matter on organotin accumulation has been studied.
Interlaboratory programme for the quality control of trimethyllead determination in the environment
Authors: Quevauviller Ph. , Wang Y. , Turnbull A. B. , Dirkx W. M. R. , Harrison R. M. , Adams F. C. 
Published: January 2005

AbstractDeterminations of the trimethyllead moiety in environmental samples are carried out by a number of laboratories in Europe. To verify the quality of such determinations, the Measurements and Testing Programme (formerly BCR) of the European Commission organised an interlaboratory exercise which allowed discussion and comparison of the different techniques used so far in lead speciation analyses. In addition, this first step enabled a study of the feasibility of the preparation of candidate reference materials (CRMs) for the determination of the trimethyllead moiety in simulated rainwater to be carried out. The solutions used in this study were carefully prepared and their homogeneity and stability verified. This paper describes the organisation and the results of the intercomparison and discusses the further development of the project.
A new family of heavy transition metal coordination compounds and its application, I. Design, synthesis and characterization of volatile organohafnium precursors
Authors: Grafov Andrei V. , Mazurenko Eugene A. , Battiston Giovanni A. , Zanella Pierino , Tisato Francesco , Braga Franco , Traldi Pietro 
Published: January 2005

AbstractThe first three representatives of a new family of volatile organohafnium compounds suitable as metallo‐organic chemical vapour deposition precursors were synthesized. A combination of cyclopentadienyl and alkoxo‐ligands with a bicyclo[2.2.1]heptanc framework was used. Volatility at relatively low temperatures for hafnium compounds was found and the precursors were characterized by elemental analysis and spectroscopic methods (IR, 1H and 13C NMR, mass spectrometry and mass‐analysed ion kinetic energy spectroscopy). The outlook for use in hafnium functional materials synthesis was derived from the fragmentation data.
Stereochemical and biochemical aspects of organoboron(III) compounds of hydrazonecarboxamides and hydrazonecarbothioamides
Authors: Saxena Chitra , Singh R. V. 
Published: January 2005

AbstractHydrazonecarboxamides and hydrazonecarbothioamides and their derivatives have important pharmacodynamic significance. In the search for better fungicides and bactericides, organoboron(III) compounds derived from these ligands were screened for their antifungal and antibacterial activities. The heterocyclic aldimines were prepared by the condensation of (2‐furanyl)methanal, (2‐thienyl)methanal, (2‐pyridinyl)methanal, (1H‐indol‐3‐yl)methanal or 3‐phenyl‐2‐propenal with hydrazinecarboxamide or hydrazine‐carbothioamide. Unimolar and bimolar reactions between phenyldihydroxyborane and these ligands have produced PhB(OH)(NO), PhB(NO)2, PhB(OH)(NS) and PhB(NS)2 types of biologically active compounds. Structural assignment has been made through UV, IR and NMR (1H, 11B and 13C) spectroscopy. TGA and XRD of a representative compounds have also been carried out. The compounds were tested in vitro against a number of fungal and bacterial strains and were found to possess moderate to good toxicity.
The fate of mercury species injected into coelomic fluid of starfish Leptasterias polaris
Authors: Maheu Sophie , Pelletier Emilien 
Published: January 2005

AbstractMature starfish Leptasterias polaris, collected in the St Lawrence Estuary (eastern Canada), were exposed to two mercury species (HgCI2 and CH3HgCI) via injections into the coelomic fluid. In vivo effects of some complexing agents (glutathione, mercaptoethanol and EDTA) on the distribution of 203Hg‐labelled species in starfish organs and tissues and their possible role in mercury transport through membranes were studied over a 24 h period. The excretion of ammonia and mercury was also measured. When injected alone, inorganic mercury and methylmercury [CH3Hg(II)] were distributed in all organs, with a preferential adsorption in gonads, pyloric caeca and stomach. Mercury excretion was very low under all conditions studied. Mercaptoethanol, a small thiol ligand, was very efficient in reducing both mercury species in the coelomic fluid and seems to have promoted translocation towards most organs of the starfish. Its action is attributed to the formation of small and neutral complexes, HgL2 and CH3HgL, which can diffuse through membranes preserving their integrity. Glutathione increased the translocation of CH3Hg(II) towards surrounding organs, but had no apparent effect on inorganic mercury. EDTA promoted the transport of inorganic mercury only. These results highlight (1) the particular interest of starfish to workers studying in vivo chemical complexation of mercury species, and (2) the potential role of complexing molecules in the biotransport of mercury species through living membranes.
Catalytic properties of metal‐containing polymethylsiloxanes
Authors: Fiedorow R. , Przystajko W. , Adamiec J. 
Published: January 2005

AbstractAluminium‐, iron‐, titanium‐ and zirconiumcontaining polymethylsiloxanes were studied as catalysts for acid‐catalysed reactions; their surface acidity and the strengths of their acid centres were determined. They appeared to be active for 2‐propanol dehydration; the best sample was almost as active as alumina, which is known for its high activity for alcohol dehydration. All metalcontaining polymethylsiloxanes (MPS) catalysed double‐bond migration and cis‐trans isomerization of 2‐butene. Some of them also catalysed the synthesis of methyl t‐butyl ether, but their activity for this reaction was inferior to that of the resin Amberlyst‐15 and some of sulphate‐ion modified metal oxides. No cumene conversion occurred on the catalysts studied and no pyridinium ion formation was observed by IR spectroscopy, which points to the absence of strong Brönsted acid sites. The MPS are distinguished by quite large surface areas (86‐299 m−2g−1) and are capable of chemisorbing pyridine (0.014‐0.047 mmolg−1) on their Lewis acid centres.
Dictionary of organometallic compounds, B. J. Aylett, M. F. Lappert and P. L. Pauson (eds) Chapman and Hall, London £2950 (hardback). £3500 CD ROM (single user). $8750 CD ROM (network). ISBN 0 412 43060 6 (five‐volume set)
Authors: Craig P. J. 
Published: January 2005

AbstractNo Absract.
Behaviorally induced changes in length of cerebrum in rats
Authors: Altman Joseph , Wallace Robert B. , Anderson William J. , Das Gopal D. 
Published: January 2005

AbstractIn normal rats, growth in the width of the cerebral hemispheres ceases about 21 days of age, but growth in length continues at a reduced, steady rate in the young‐adult. Three behavioral treatments were used to determine whether this late phase in cerebral growth is sensitive to environmental influences. Rats that were trained on a complex visual discrimination task for 4 months had significantly longer cerebral hemispheres than their passive littermates. Rats that were raised in enriched or social environments had longer cerebral hemispheres than rats raised in isolation. Finally, the cerebrum of unhandled rats was shorter than that of rats handled during infancy; that of the latter was shorter than the cerebrum of trained or enriched animals. No changes were observed under any of these conditions in cerebral width. These results indicate that the length of the cerebrum characteristic of normal rats does not represent a genetically determined, fixed level. This level is not attained under certain rearing conditions and it can be surpassed when the complexity of the environment is increased. The morphological bases of these changes were not determined.
Rabbit eyelid conditioning: Effects of age, interstimulus interval, and intertrial interval
Authors: Frey Peter W. , Ross Leonard E. 
Published: January 2005

AbstractYoung rabbits (5–7 weeks old) conditioned more rapidly and demonstrated longer latency responses than older rabbits (14–20 weeks old) with an 800‐msec interstimulus interval. With a 200‐ or 400‐msec interval, conditioning rate and response latency were similar for both age groups. Although a 4‐min intertrial interval produced conditioning in fewer trials than a 1‐min interval, there was no interaction of this variable with the age factor.
Effects of differential environments on brain weights and enzyme activities in gerbils, rats, and mice
Authors: Rosenzweig Mark R. , Bennett Edward L. 
Published: January 2005

AbstractIn 2 experiments, littermate male gerbils were kept in enriched (EC), standard colony (SC), or impoverished (IC) environments from 30 to 60 days of age. Cerebral effects of these environmental treatments were compared with results obtained previously with laboratory rats and mice. The EC gerbils show, in comparsion with IC, an increase in cortical weight and an increase in the cortical/subcortical weight ratio, a decrease in cortical acetylcholinesterase per unit of weight, and a slight increase in the ratio of cholinesterase to acetylcholinesterase in the cortex. These changes for the most part follow the pattern of EC‐IC effects found in the rat and mouse. In both absolute brain measures and in EC‐IC effects, the gerbil resembles the rat more closely than the mouse. The results extend the generality of findings within Rodentia from the family Muridae, which includes rats and mice, to the family Cricetidae, to which gerbils belong. Furthermore, the gerbil, unlike the laboratory rat and mouse, has not been subjected to many years of selection for laboratory conditions.
Estimation of catecholamines in the brains of embryonic and newly hatched chickens and the effects of reserpine
Authors: Sparber S. B. , Shideman F. E. 
Published: January 2005

AbstractReserpine significantly decreased the concentrations of atecholamines (CA) in the brains of 14‐ and 18‐day‐old chicken embryos when administered prior to incubation in a dose that has little or no effect upon hatchability. Administration of this drug had profound effects upon the fluorometric estimation of CA in the brains of both embryonic and newly hatched chicks. This can lead to an erroneous interpretation of the quantitative effects of reserpine on CA concentrations in the brain.