bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetics of the utilization of different C sources and the cellulose formation by Acetobacter xylinum
Authors: Geyer U. , Klemm D. , Schmauder H.‐P. 
Published: December 2004

AbstractDifferent methylated glucose derivatives and cellobiose were examined as the carbon sources for growth and cellulose formation by Acetobacter xylinum. HPLC studies were carried out to gain information about the kinetics of the utilization of the C sources used. The type and yields of the synthesized cellulose were described. Besides glucose, cellobiose was a substrate for the synthesis of this polysaccharide by the bacteria. Other methylated derivatives of glucose were not accepted for a comparable synthesis of this polymer. An estimation of citrate in an unmodified culture liquid (SH medium) showed utilization in a late phase of cultivation. The influence of this organic acid on the pH value, cellulose synthesis and growth is described. By the application of citric acid as a sole carbon source “gel‐like” forms of cellulose were formed generally.
Separation of D‐forms and L‐forms of DL‐aspartic acid derivatives by the enzyme subtilisin DY
Authors: Milev L. , Vezenkov L. , Yotova L. 
Published: December 2004

AbstractThe ability of the enzyme subtilisin DY for the synthesis of derivatives of DL‐aspartic acid which are differently N and C‐terminal protected and semiproducts of the peptide synthesis was investigated. The enzyme reaction was characterized by high yields and a comparatively short reaction time. Two of the substrates, Z‐D,L‐Asp‐(OMe)2 and PhAc‐D,L‐Asp‐(OMe)2, were hydrolyzed for about 15 min; the reaction time for Boc‐D,L‐Asp‐(OMe)2 was 2.5 h. The values for the MICHAELIS constants obtained for Z‐D,L‐Asp‐(OMe)2 (Km = 0.576 mM) and PhAc‐D,L‐Asp‐(OMe)2 (Km = 0.300 mM) showed a high affinity of the enzyme to the substrates. For Boc‐D,L‐Asp‐(OMe)2 the affinity of the enzyme is considerable lower (Km = 14.07 mM).The results of these investigations can be effectively used for the separation of N‐protected derivatives of D,L‐aspartic acid and with a high probability also for other amino and racemic forms.
Trends in biotechnology: Sustainable technology development: From high tech to Eco Tech
Authors: Moser A. 
Published: December 2004

AbstractBiotechnology as a multidisciplinary and transdisciplinary field of science and engineering is regarded to be a key technology for the future, able to essentially contribute to sustainable development. In the first part of this paper, a critical analysis of the status quo in biotechnologies is given in the area of pharmaceutical, agricultural, environmental, and industrial biotechnology as well as food biotechnology. Here the general potential becomes clear, but also a series of disadvantages which are partly the result of the existing paradigm in science and technology and partly in direct connection to bioprocessing itself. Nevertheless, these biotechnologies will contribute to sustainable development, but mainly in a shallow sense of survival and livelihood.In the second part of this paper, another new dimension in bioprocessing is elucidated, which is in agreement with the new ecological, holistic world view. Here the so‐called “eco‐principles” are derived from a systems analysis of the ecosphere and represent the intelligence of nature as the result of evolution. The eco‐principles will serve as guidelines for the general eco‐restructuring of technology, being a drastic change within the next 2–5 decades. For the applying of eco‐principles, a quantitative measure for sustainability in technology was developed (“sustainable process index”), which will enable us to design the new technology paradigm called “Eco Tech”. Ecological security and social equity, together with economic efficiency will define sustainable technology development in a deeper sense.Following this route, a completely new dimension of biotechnology will be reached, where the technosphere is fully embedded into the natural cycles of the ecosphere on a local basis.
Colonisation of seedling roots by 2,4‐D degrading bacteria: A plant‐microbial model
Authors: Zwieten L. , Feng L. , Kennedy I. R. 
Published: December 2004

AbstractThe development of model plant‐microbial associations between Gram negative soil microbes capable of degrading phenoxyacetate herbicides, such as 2,4‐D and 2,4‐D methyl ester, and the crops canola and wheat was described. Both an Acinetobacter baumannii pJP4 transconjugant and Alcaligenes eutrophus JMP 134 colonised non‐parasitically on the roots of sterilised seedlings in a hydroponic system. Laser scanning confocal microscopy has shown that colonisation occurred both on the root surface and deeper inside the mucilage layer or inside some surface root cells. When 2,4‐D was added to the hydroponic medium supporting the growth of those seedlings colonised by 2,4‐D degrading bacteria, the gas chromatographic analysis showed a rapid decrease in the concentration of this herbicide. These bacteria colonising the root system were shown to be responsible for the degradation of 2,4‐D. Plants inoculated with the 2,4‐D degrading microbes were subsequently found to be less susceptible to damage by the herbicide in such hydroponic systems.
Characterization of biosurfactants and their use in pollution removal – State of the Art. (Review)
Authors: Banat I. M. 
Published: December 2004

AbstractSurface‐active compound of biological origin (biosurfactants) have only been described in the past few decades. With the advantage of biodegradability and production on renewable resources, biosurfactants have been gaining prominence and their applications are becoming wider. So far, literature contains mixed reports on the successes of the applications of biosurfactants and their economical viability. They remain compounds which are not very well understood, yet, with several important applications. The target industries for biosurfactant use are the petroleum remediation industries and environmental conservation agencies. These industries, however, seem reluctant to use them for fear of dealing with microbes or microbial products. This includes cleaning up oil spills from the environment, remediation of metal‐contaminated soils or waste streams, mobilizing heavy oil sludge and enhanced oil recovery. The importance of biosurfactants, their production, characteristics and limited successes and applications in oil pollution remediation and oil storage tank cleaning are discussed.
Airborne bacteria and fungal spores in the indoor environment. A case study in Singapore
Authors: Goh I. , Obbard J. P. , Viswanathan S. , Huang Y. 
Published: December 2004

AbstractThe concentration of airborne fungal spores and bacteria as related to room temperature, humidity and occupancy levels within a library building in Singapore was determined. Measurement of indoor air quality with respect to microorganisms is of particular importance in tropical environments due to the extensive use of air‐conditioning systems and the potential implications for human health. This study has revealed a number of interesting relationships between the concentrations of fungal spores and bacteria in relation to both environmental and human factors. The levels of fungal spores measured in the indoor environment were approximately fifty times lower than those measured outside, probably because of the lowered humidity caused by air‐conditioning in the indoor environment. The variation in fungal spore concentration in the outdoor environment is likely to be due to the diurnal periodicity of spore release and the response to environmental factors such as light temperature and humidity. The indoor concentration of fungal spores in air was not clearly correlated to concentrations measured in air outside of the library building and remained relatively constant, unaffected by the difference in the numbers of occupants in the library. In contrast, the indoor concentrations of bacteria in air were approximately ten times higher than those measured outdoors, indicating a signficant internal source of bacteria. The elevated levels of indoor bacteria were primarily attributed to the number of library occupants. Increased human shedding of skin cells, ejection of microorganisms and particulates from the respiratory tract, and the transport of bacteria on suspended dust particles from floor surfaces probably accounts for the strong positive correlation between occupancy levels and the concentration of bacteria in internal air.
Phase behavior of discotic liquid crystalline polymers and related model compounds
Authors: Kranig Wolfgang , Hüser Bernhard , Spiess Hans W. , Kreuder Willi , Ringsdorf Helmut , Zimmermann Herbert 
Published: December 2004

The phase behavior of liquid cyrstalline polymers and oligomer model compounds with alkylated tripheylenes (see figure) as the mesogenic core is studied using a combination of optical microscopy, DSC and 2H NMR. The information provided by NMR provides unique insights into the behavior of liquid crystalline phases.magnified image
Chemically modified metal surfaces—a new class of composite materials
Authors: Stratmann Martin 
Published: December 2004

AbstractThis promising method of chemically modifying reactive metal surfaces with organic molecules prior to the attachment of polymers could have a significant impact on work aimed at the optimization of the performance of composite materials. Strong chemical bonds can be formed between a suitably prepared metal surface and certain monomers, which resist even an electrochemical polarization of the interface at large cathodic or anodic overpotentials. These chemical bonds can, however, only be achieved if a suitable structure and reactivity is generated, for example, by using electrochemical techniques. Therefore, further technological progress in this important area requires the cooperation of scientists from rather different scientific disciplines like electrochemistry, surface science and organic chemistry, in order to optimize the structure of the organic monomers and to provide the best possible bonds to the different metals in use, taking into account the rather different reactivity of technologically important media.
Molecular recognition directed self‐assembly of supramolecular liquid crystalline polymers from complementary chiral components
Authors: Fouquey Claudine , Lehn Jean‐Marie , Levelut Anne‐Marie 
Published: December 2004

The self‐assembly of intelligent supermolecular materials, for example, liquid crystalline polymers, is the subject of this communication. Employing units based on tartaric acid in the molecular recognition process (see figure) allows the effects of chirality to be investigated as the recognition which occurs at a molecular level is reflected in the properties of the macroscopic mesophases formed.
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Aligned molecular sieve crystals
Authors: Caro Jürgen , Finger Gerd , Kornatowski Jan , Richter‐Mendau Jürgen , Werner Lutz , Zibrowius Bodo 
Published: December 2004

The controlled incorporation of guest molecules in zeolites opens the way to novel materials with desirable optical, magnetic, or electronic properties. The properties of the guests are often direction dependent and therefore the bulk orientation of the host matrixes (see figure) in an electric field can lead to greatly enhanced performance. magnified image
White light emission from C60 molecules confined in molecular cage materials
Authors: Hamilton Bruce , Rimmer J. S. , Anderson M. , Leigh D. 
Published: December 2004

Confining C60 in the cages within a zeolite (see Figure) results in the modification of the optical properties of the fullerene. This possibly results from a weak interaction of the C60 with the wall of the zeolite which is, however, strong enough to perturb the electronic structure of the C60 resulting in otherwise forbidden transitions (e.g. white light emission) being observed. magnified image
Synthesis and electropolymerization of 3‐(3,3,4,4,5,5,6,6,6‐nonafluorohexyl‐1‐dimethylsilyl thiophene): Reduction of steric hindrance in 3‐substituted poly(thiophenes) by fluorophilic interactions
Authors: Thobie‐Gautier Christine , Guy Alain , Gorgues Alain , Jubault Michel , Roncali Jean 
Published: December 2004

Fluoropolymers and conjugated poly(thiophenes) both exhibit exceptional properties: the fluoropolymers are known for their low coefficient of friction, high thermal and chemical stability, hydrophobicity and lipophobicity, while poly(thiophenes) allow the design of tailored conducting polymers. A combination of these properties would be of great interest. The title compound (see Figure) can be readily electropolymerized, yielding a hydrophobic conjugated polymer with doping level and conductivity comparable to those of its alkyl‐substituted analogue. magnified image
Nematic liquid crystalline mineral polymers
Authors: Davidson Patrick , Gabriel Jean‐Christophe , Levelut Anne‐Marie , Batail Patrick 
Published: December 2004

Anisotropic fluids are demonstrating that liquid crystals need not be organic. Recent theories predict the existence of lyotropic liquid crystalline phases for particular anisotropies and concentrations of the fluid‐constituting objects, regardless of their chemical nature. Attention has been focused on the solution‐phase chemistry of LiMo3Se3, which dissolves in highly polar solvents to give very long Mo3Se3 strings (the Figure shows a texture photograph of LiMo3Se3 in N‐methylformamide). magnified image
Nanoporous tin(IV) sulfides: Mode of formation
Authors: Jiang Tong , Ozin Geoffrey A. , Bedard Robert L. 
Published: December 2004

Nanoporous R‐SnS‐n materials e.g. (Et4N)2Sn3S7, have been sythesized and characterized. The crystal structures of two molecular tin(IV) sulfide species that are thought to be important in the formation of these materials are reported. Both contain the dimer (Sn2S6)4⊖, which can be combined (see Fingure) to form the Sn4S4 broken‐cube clusters that constitute the open framework of R‐SnS‐1. magnified image
Photoinitiation of vinyl polymerization by polysilanes
Authors: Wolff Andrew R , West Robert 
Published: January 2005

AbstractPolysilanes were found to photoinitiate the polymerization of a variety of vinyl monomers including methyl methacrylate, styrene, ethyl acrylate and acrylic acid. Polymerization initiated by polysilane photolysis is rather insensitive to oxygen inhibition, which may make it especially suitable for polymerization of thin films. The initiation efficiency of poly(phenylmethylsilylene) in styrene was determined from dilatometry data to be 1 × 10−3. This rather low efficiency is counterbalanced by the very high extinction coefficient of polysilane polymers, ca. 4–8 × 103 per silicon atom. Possible reasons for the low initiation efficiency and reduced oxygen inhibition of polysilane photoinitiators are discussed.
Methylation of tin(II) and lead(II) in sediment by carbanion donors
Authors: Rapsomankis Spyridon , Donard Olivier F X , Weber James H 
Published: January 2005

AbstractA factorial experimental design determined separate and combined effects of MeCoB12 (methylcobalamin) and Me2Co(N4)+ (a methylcobalamin model) on methylation of Sn(II) and Pb(II) in sediment matrices. Total methyltin yields ranged from 1.4% to 3.2%, and total methyllead yields varied from 0.037% to 0.11%. No methylmetal products occurred in the absence of Me2Co(N4)+.
Synthesis, 119Sn NMR and Mössbauer studies and bioassay data of O‐tricyclohexylstannyl derivatives of substituted 8‐hydroxyquinolines
Authors: Blunden S J , Patel B N , Smith P J , Sugavanam B 
Published: January 2005

AbstractEight novel tricyclohexyltin derivatives of substituted 8‐hydroxyquinolines have been synthesised and their structures studied in the solid state by 119mSn Mössbauer and, in solution, by 119Sn NMR, spectroscopy. Bioassay data are reported for these compounds against an organophosphorus‐resistant species of the two‐spotted spider mite, Tetranychus urticae, and a range of fungal and bacterial diseases of crops. The relationship between the activity and the coordination number of the tin atom is discussed, and it is shown that the anionic group can, in some cases, significantly affect the biological properties.
Synthesis of metal‐containing carbohydrate polymers employing crown ether phase transfer catalyzed interfacial condensation
Authors: Naoshima Y , Carraher C E , Iwamoto S , Shudot H 
Published: January 2005

AbstractPhase transfer catalyzed interfacial reaction of the polysaccharide dextran (C6H10O5)n with organotitanium and organotin dichlorides to form metal‐containing carbohydrate polymers has been carried out in the presence of two bases, sodium hydroxide and triethylamine. Interfacial systems employing sodium hydroxide with a crown ether phase transfer catalyst (PTC) gave generally greater yields compared with the analogous systems without a PTC. The trend of maximum yield for triethylamine systems with organotin dichloride not containing a PTC was different from that observed for the sodium hydroxide systems without a PTC, probably because of the ability of triethylamine to act as a PTC.
Synthesis of 14C‐radiolabelled trimethyllead chloride
Authors: Blais J S , Marshall W D 
Published: January 2005

AbstractTwo synthetic routes to 14C‐labelled trimethyllead chloride ((CH3)3PbCl) from 14C‐methyl iodide (CH3I) were investigated. Alkylation of (CH3)3PbCl with labelled methylmagnesium halide, on a microscale, was less efficient for the synthesis of tetramethyllead ((CH3)4Pb) than was an electrochemical reduction of labelled CH3I at a sacrificial lead cathode. In the Grignard approach, unlabelled decyl bromide served as an initiator for the reaction of 14C‐CH3l with excess Mg and as a carrier during the subsequent alkylation of (CH3)3PbCl. In the electrochemical approach a two‐compartment cell, using dimethylformamide as solvent and sodium perchlorate as supporting electrolyte, offered several advantages over a single compartment reactor. The labelled (CH3)4Pb from both reactions was isolated by extraction, converted to (CH3)3PbCl by controlled oxidation with HCl and purified by thin layer chromatography.
The synthesis and tin‐119m Mössbauer spectra of a series of di (4‐substituted phenyl) tin dichloride complexes with nitrogen‐donor ligands
Authors: Biddle B N , Gray J S , Crowe A J 
Published: January 2005

AbstractThe synthesis and 119mSn Mössbauer spectra of a series of 12 new and 3 other organotin complexes of general structure (4‐ZC6H4)2SnCl2.L2.(Z = CH3, CF3, F, Cl, OCH3, L2=2,2′‐bipyridyl, 1,10‐phenanthroline, 2‐aminomethylpyridine) arereported. A convenient method for the preparation of the intermediate diaryltin(IV) dihalides is given. The complexes fall into two isomeric types with either a trans‐ or cis‐[ArSnAr] geometry. For this series 2‐aminomethylpyridine gives exclusively the cis‐[ArSnAr] geometry in its complexes.
Catalysis of hydrosilylation XIII. Gas‐phase hydrosilylation of acetylene by trichlorosilane on functionalised silica supported rhodium and ruthenium phosphine complexes
Authors: Marciniec Bogdan , Foltynowicz Zenon , Urbaniak WŁOdzimierz , Perkowski Juliusz 
Published: January 2005

AbstractGas‐phase hydrosilylation of acetylene by tri‐chlorosilane catalyzed in a continuous flow apparatus by rhodium and ruthenium phosphine complexes immobilized on the silica via mercapto, phosphine, amine and nitrile ligands has been studied. GLC analysis of the reaction products showed vinyltrichlorosilane to be accompanied by products of double hydrosilylation of acetylene and the redistribution of trichlorosilane followed by the hydrosilylation and hydrogenative hydrosilylation of acetylene with dichlorosilane. A scheme for this complex competitive–consecutive reaction was proposed. The yield and selectivity of vinyltrichlorosilane can be much improved under special reaction conditions, e.g. rate flow of the particular substrates, temperature, given catalyst and others. Kinetic measurements carried out in the range of 115–140°C allowed us to evaluate the activation energy, Ea, for the vinyltrichlorosilane synthesis, which varied between 20.5 and 27.6 kJ mol−1 for the selected rhodium and ruthenium supported complexes.
Metal catalysed Brooke rearrangement of 3‐Halo‐1‐(trimethylsilyl) propan‐2‐one (Halo = Cl or Br)
Authors: Jones Michael D , Kemmitt Raymond D W 
Published: January 2005

AbstractThe complexes [IrH(CO)(PPh3)3], trans‐[IrCI(CO)‐ (PPh3)2], [RhH(PPh3)4], [Pd(PPh3)4], [Pt(trans‐stilbene)(PPh3)2] and [Pt(η3‐CH2‐COCH2)‐(PPh3)2] catalyse the rearrangement of Me3SiCH2C(O)CH2Cl to CH2C(OSiMe3)‐CH2Cl.
Antifeedant effects of mixed methylphenyl hexaorganoditin compounds of the type PhnMe6–nSnSn on larvae of Spodoptera littoralis and Epilachna varivestis
Authors: Ascher K R S , Eliyahu M , Bultent E J , Meinema H A 
Published: January 2005

AbstractCompounds of the series PhnMe6–nSn2 were prepared and tested for their antifeedant effects against Spodoptera littoralis (Boisduval) and Epilachna varivestis (Mulsant) larvae. In addition, phytotoxicity towards bean seedlings was measured. The most active compound against both Spodoptera and Epilachna was Ph3Me3Sn2. The compound at 50 mg dm−3 was comparatively innocuous in phytotoxicity tests against bean seedlings.
Regioselective phthalation and succinylation of D‐glucose and D‐galactose using protecting groups: Conversion of the products to organotin derivatives
Authors: Patel Atula , Poller Robert C , Rathbone Elner B 
Published: January 2005

Abstract1,2: 5,6‐Di‐O‐isopropylidene‐α‐D‐glucofuranose was acylated at the free 0‐3 position with phthalic and succinic anhydrides. Removal of the protecting groups gave the 3‐O‐acylglucopyranose compounds which were converted to their acetyl and organostannyl derivatives. A similar sequence of reactions was carried out with 1,2:3,4‐di‐O‐isopropylidene‐α‐D‐galactopyranose.
Molybdenum‐Containing polysalts of the poly[ferricene‐1,2(1,3:1,1′)diyl‐methylene] cation
Authors: Neuse Eberhard W , Khan Fathima B D 
Published: January 2005

AbstractPoly(ferricene‐1,2(1,3:1,1′)diyl‐methylene) polycations, generated from the neutral precursor polymer 1 (M̄n=2800) by dioxygen (O2) oxidation in sulfuric acid medium, are paired first, in a model reaction, with the hexafluorophosphate anion and, in the principal series of experiments, with the two molybdenum‐containing complex anions, octamolybdate and phosphododecamolybdate. The model poly(hexafluorophosphate) 2b, as well as the polymolybdates 2c and 2d, precipitate from aqueous acidic solution of the corresponding polysulfate 2a after anion exchange; scopically. In addition to the hexafluorophosphate anion, the model polysalts 2b contain small proportions, typically 5‐15%, of sulfate anion (probably present as HSO), indicating incompleteness of the anion exchange process. Analytical data suggest similarly incomplete exchange of anions also for the polymolybdates 2c and 2d. Oxidation of ferrocene units along the polymer chain is practically complete in the great majority of polysalts 2 synthesized. The molybdenum‐containing polymers are of interest as plant micronutrients possessing slow‐release properties.
Hydrosoluble transition‐metal coordination compounds of triphenylphosphine m‐trisulfonate
Authors: Larpent Chantel , Patin Henri 
Published: January 2005

AbstractBy using 31P NMR and IR techniques it is established that the basicities of triphenylphosphine m‐trisulfonate (TPPTS) and triphenylphosphine (PPh3) are in the same order of magnitude. This highly hydrosoluble phosphine is a convenient ligand for the synthesis of hydrosoluble coordination compounds of molybdenum(0), palladium(II), platinum(II) and rhodium(I). The exchange of TPPTS with ligands other than PPh3 (nitriles, carbon monoxide, olefins, chloride) can be used to obtain the desired complexes. However, because redox reactions between metal salts, water and TPPTS are possible, the synthesis of lowvalent precursors must be carried out and the experimental conditions have to be carefully controlled to avoid side‐reactions and the participation of the sulfonate anions in competitive reactions.