Home About us Contact
|
Home About us Contact | ||
|
|
||
Silver Ions (silver + ion)
Selected AbstractsA Bis-Oxime Derivative of Diaza-18-Crown-6 as an Ionophore for Silver IonELECTROANALYSIS, Issue 11 2005Michael Abstract A new pendant-arm derivative of diaza-18-crown-6, containing two oxime donor groups, has been synthesized and incorporated into a polyvinyl chloride (PVC) membrane ion-selective electrode. The electrode shows selectivity for Ag+ ion, with a near Nernstian response. Pb2+, Cu2+, Hg2+, and Tl+ are major interfering ions, with Cd2+ having minor interference. The electrode shows no potentiometric response for the ions Mg2+, Al3+, K+, Ca2+, Ni2+, Fe3+, and La3+, and is responsive to H+ at pH<6. [source] Mixed Aza-Thioether Crowns Containing a 1,10-Phenanthroline Sub-Unit as Neutral Ionophores for Silver IonELECTROANALYSIS, Issue 24 2002Mojtaba Shamsipur Abstract Three different recently synthesized aza-thioether crowns containing a 1,10-phenanthroline sub-unit (L1,L3) and a corresponding acyclic ligand (L4) were studied to characterize their abilities as silver ion ionophores in PVC-membrane electrodes. Novel conventional silver-selective electrodes with internal reference solution (CONISE) and coated graphite-solid contact electrodes (SCISE) were prepared based on one of the 15-membered crowns containing two donating S atoms and two phenanthroline-N atoms (L1). The electrodes reveal a Nernstian behavior over wide Ag+ ion concentration ranges (1.0×10,5,1.0×10,1,M for CONISE and 5.0×10,8,4.0×10,2,M for SCISE) and very low limits of detection (8.0×10,6,M for CONISE and 3.0×10,8,M for SCISE). The potentiometric response is independent from pH of the solution in the pH range 3.0,8.0. The electrodes manifest advantages of low resistance, very fast response and, most importantly, good selectivities relative to a wide variety of other cations. The electrodes can be used for at least 2 months (for CONISE) and 4 months for (SCISE) without any appreciable divergence in potentials. The electrodes were used as an indicator electrode in the potentiometric titration of Ag+ ion and in the determination of silver in photographic emulsions and in radiographic and photographic films. [source] Electronic Structure and Solvation of Copper and Silver Ions: A Theoretical Picture of a Model Aqueous Redox ReactionCHEMINFORM, Issue 23 2004Jochen Blumberger Abstract For Abstract see ChemInform Abstract in Full Text. [source] Preparation of Novel Arrays Silver Nanoparticles Modified Polyrutin Coat-Paraffin-Impregnated Graphite Electrode for Tyrosine and Tryptophan's OxidationELECTROANALYSIS, Issue 8 2008Guan-Ping Jin Abstract A novel array silver nanoparticles and Rutin complex film modified paraffin-impregnated graphite electrode was proposed in this work (denoted as Ag/Rutin/WGE). The characteristics were investigated by the field emission scanning electron microscopy (FE-SEM), infrared spectra (IR), UV-visible (UV), X-ray photoelectron spectroscopy (XPS) and electrochemical techniques. Silver ions were gradually chelated by polyrutin film at 4,-oxo-5,-OH and 5-OH-4-oxo sites accompanying adsorption, then. Silver nanoparticles were highly-dispersed electrodeposited on polyrutin film. The electrochemical behaviors of tyrosine (Tyr) and tryptophan (Trp) were studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The Ag/Rutin/WGE electrode shows overlapping catalysis for the oxidation of Tyr and Trp. The linear response of Tyr and Trp were 0.3,10.0 and 0.7,70.0,,M with detection limit of 0.07 and 0.1,,M in a signal-to-noise ratio of 3. [source] Therapeutic Window for Bioactive Nanocomposites Fabricated by Laser Ablation in Polymer-Doped Organic Liquids,ADVANCED ENGINEERING MATERIALS, Issue 5 2010Anne Hahn Abstract Polymeric nanomaterials are gaining increased interest in medical applications due to the sustained release of bioactive agents. Within this study nanomaterials are fabricated using laser ablation of silver and copper in polymer-doped organic liquids thus allowing to produce customized drug release systems. A strategy is shown to determine the therapeutic window for cells relevant for cochlear implant electrodes, defined by the viability of L929 fibroblasts, PC12 neuronal cells, and spiral ganglion cells on different concentrations of silver and copper ions. The distribution of nanoparticles within the silicone polymer matrix is determined using transmission electron microscopy. Hexane doped with 1% silicone resin is found to be an appropriate liquid matrix to fabricate a nanocomposite with a constant ion release rate. Silver ions of 10,µmol L,1 or copper ions of 100,µmol L,1 cause a suppression of tissue growth without inhibiting neuronal cell growth. The copper nanoparticle content of 0.1,wt% of the silicone composite releases ion concentrations which fit the therapeutic window. [source] Soft Metal Ion-Selective Electrodes Based on ,-Coordinate Calixarene DerivativesELECTROANALYSIS, Issue 15-16 2003Setsuko Yajima Abstract Calix[4]arene derivatives incorporating ,-unsaturated alkenyl groups or saturated alkyl groups and their monomeric analogues were used as ,-coordinate neutral carriers for ion-selective electrodes (ISEs) of soft metals [silver and thallium(I)] ions. The EMF responses were excellent for most of the ISEs, among which there was no significant difference in the response. The ion selectivities of the ISEs depend on the structure of neutral carriers employed. 1H NMR study explains the difference in the ion selectivity. In the metal-ion complexation by the ,-coordinate calixarene derivatives, thallium ion is likely to interact with the calixarene skeleton, while silver ion tends to interact with both of the calixarene skeleton and the ,-unsaturated alkenyl groups. [source] Modeling of extraction behavior of docosahexaenoic acid ethyl ester by utilizing slug flow prepared by microreactorAICHE JOURNAL, Issue 8 2010Eiji Kamio Abstract The liquid,liquid extraction dynamics of an ethyl ester of docosahexaenoic acid (DHA-Et) with silver ion was investigated. The kinetic model was derived according to the following stepwise processes: Diffusion of DHA-Et across the organic film, complex-formation between DHA-Et and silver ion at the interface, and diffusion of extracted complex across the aqueous film. The kinetic parameters for the complex-formation reaction were determined from the investigation with the stirred transfer cell. With the proposed model and determined parameters, we predicted the uptakes of DHA-Et for the extraction system utilizing a slug flow prepared by a microchip. The calculated uptakes showed good correlation to the experimental data. The theoretical investigation suggested that the fast equilibration realized for the slug flow extraction system was due to the large specific interfacial area of the slug caused by the presence of wall film and the thin liquid film caused by the internal circulation. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Cation,, complexes of a bowl-shaped polycyclic aromatic hydrocarbonJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 9 2004Ronald B. M. Ansems Abstract Circumtrindene (1), a C36H12 geodesic polyarene that represents 60% of fullerene-C60, forms cation,, complexes with both silver ion (1·Ag+) and tetramethylammonium ion [(Me)4N+·1] in chloroform solution at room temperature (Ka>20,M,1 for both cations). Preferential binding in the concave pocket of 1 is predicted by DFT calculations for both cations; however, this stereochemical assignment has not yet been confirmed experimentally. Copyright © 2004 John Wiley & Sons, Ltd. [source] Separation of triacylglycerols in a complex lipidic matrix by using comprehensive two-dimensional liquid chromatography coupled with atmospheric pressure chemical ionization mass spectrometric detectionJOURNAL OF SEPARATION SCIENCE, JSS, Issue 8 2006Paola Dugo Abstract The present investigation describes the employment of a comprehensive 2-D HPLC system, based on the combination of a silver ion and an RP column, for the characterization of the triacylglycerol (TAG) fraction of a very complex lipidic sample: donkey milk fat. The TAGs were grouped on the resulting bidimensional contour plot according to their double bond numbers (aligned along vertical bands) and according to their partition numbers (aligned along horizontal bands). Peak assignment was supported by using atmospheric pressure chemical ionization mass spectrometric (APCI-MS) detection. The combination of the enhanced resolving power of comprehensive multidimensional LC, the formation of ordered 2-D patterns, and APCI-MS detection proved to be an effective tool for the characterization of the complex matrix, enabling the separation and identification of nearly 60 TAGs. [source] 1D Ladder-like Chain and 1D Channeled 3D Supramolecular Architectures Based on Benzophenone-2,4,-dicarboxylic AcidCHINESE JOURNAL OF CHEMISTRY, Issue 4 2008Xiao-Gang YANG Abstract The hydrothermal reactions of AgNO3, 2,2,-bipyridyl, and benzophenone-2,4,-dicarboxylic acid gave rise to two 3D supramolecular architectures, namely H2L·H2O (1), [Ag(bpy)2]·HL·H2O (2) (bpy2,2,-bipyridyl, H2Lbenzophenone-2,4,-dicarboxylic acid). The two compounds are extended by hydrogen bonds in two different approaches. In the case of 1, one-dimensional ladder-like structure is firstly formed through O,H···O hydrogen bonding between H2L ligands and water molecules, then extended to a 3D supramolecular architecture. Compound 2 possesses 3D supramolecular architecture containing 1D open channels, which are driven due to the strong H-bonding interactions occurring between the HL anions and water molecules; interestingly, [Ag(bpy)2]+ cations are linked together through ,-, interactions between bpy ligands and weak Ag···Ag interactions, and then reside in these channels by C,H···O hydrogen-bond. The photoluminescence properties of these compounds were also investigated, the emission maxima for 2 exhibits red-shift compared with that of free ligand and 1 due to chelating effect of the 2,2,-bipyridine ligand to the silver ion and the presence of aromatic ,-packing. [source] Silver (Ag+) reduces denitrification and induces enrichment of novel nirK genotypes in soilFEMS MICROBIOLOGY LETTERS, Issue 2 2007Ingela Noredal Throbäck Abstract The use of silver ions in industry to prevent microbial growth is increasing and silver is a new and an overlooked heavy-metal contaminant in sewage sludge-amended soil. The denitrifying community was the model used to assess the dose-dependent effects of silver ions on microorganisms overtime in soil microcosms. Silver caused a sigmoid dose-dependent reduction in denitrification activity, and no recovery was observed during 90 days. Dentrifiers with nirK, which encodes the copper nitrite reductase, were targeted to estimate abundance and community composition for some of the concentrations. The nirK copy number decreased by the highest addition (100 mg Ag kg,1 soil), but the nirK diversity increased. Treatment-specific sequences not clustering with any deposited nirK sequences were found, indicating that silver induces enrichment of novel nirK denitrifiers. [source] Antibacterial Coatings: Genetically Engineered Phage Fibers and Coatings for Antibacterial Applications (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 2 2010Mater. Genetic manipulation of viruses can be used to fabricate antibacterial fibers and coatings comprising crosslinked M13 bacteriophages, which are modified to bind silver ions. On page 209, Krystyn Van Vliet and co-workers demonstrate the bactericidal effects of such silverized phage fibers against several types of bacterial challenges including those potentially arising from use as wound dressings or antibacterial textiles. [source] Genetically Engineered Phage Fibers and Coatings for Antibacterial ApplicationsADVANCED FUNCTIONAL MATERIALS, Issue 2 2010Joan Y. Mao Abstract Multifunctionality can be imparted to protein-based fibers and coatings via either synthetic or biological approaches. Here, potent antimicrobial functionality of genetically engineered, phage-based fibers and fiber coatings, processed at room temperature, is demonstrated. Facile genetic engineering of the M13 virus (bacteriophage) genome leverages the well-known antibacterial properties of silver ions to kill bacteria. Predominant expression of negatively charged glutamic acid (E3) peptides on the pVIII major coat proteins of M13 bacteriophage enables solution-based, electrostatic binding of silver ions and subsequent reduction to metallic silver along the virus length. Antibacterial fibers of micrometer-scale diameters are constructed from such an E3-modified phage via wet-spinning and glutaraldehyde-crosslinking of the E3-modified viruses. Silverization of the free-standing fibers is confirmed via energy dispersive spectroscopy and inductively coupled plasma atomic emission spectroscopy, showing ,0.61,µg cm,1 of silver on E3,Ag fibers. This degree of silverization is threefold greater than that attainable for the unmodified M13,Ag fibers. Conferred bactericidal functionality is determined via live,dead staining and a modified disk-diffusion (Kirby,Bauer) measure of zone of inhibition (ZoI) against Staphylococcus epidermidis and Escherichia coli bacterial strains. Live,dead staining and ZoI distance measurements indicate increased bactericidal activity in the genetically engineered, silverized phage fibers. Coating of Kevlar fibers with silverized E3 phage exhibits antibacterial effects as well, with relatively smaller ZoIs attributable to the lower degree of silver loading attainable in these coatings. Such antimicrobial functionality is amenable to rapid incorporation within fiber-based textiles to reduce risks of infection, biofilm formation, or odor-based detection, with the potential to exploit the additional electronic and thermal conductivity of fully silverized phage fibers and coatings. [source] Assessment of bismuth thiols and conventional disinfectants on drinking water biofilmsJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2003F. Codony Abstract Aims: Biofilms in water distribution systems represent a far more significant reservoir of micro-organisms than the water phase. Biofilms are (i) resistant to disinfectants, (ii) nuclei for microbial regrowth, (iii) a refuge for pathogens, (iv) accompanied by taste and odour problems, and (v) corrode surfaces. The effects of the current strategies for disinfection of drinking water systems in large buildings (chlorination, copper and silver ionization, and hyper-heating) were compared with a new generation of bismuth thiol (BT) biocides. Methods and Results: Multispecies biofilms were treated with 0·8 mg l,1 of free chlorine, 400 and 40 ,g l,1 of copper and silver ions, respectively, at 55 and 70°C, and bismuth-2,3-dimercaptopropanol (BisBAL). Furthermore, the effect of combined heat and BisBAL on planktonic cell viability was examined in monoculture using Escherichia coli suspensions. Inactivation rates for BisBAL were similar to copper,silver ions, where the effects were slower than for free chlorine or temperature. The BisBAL effect on E. coli monocultures was augmented greatly by increasing temperatures. Conclusions: Like copper,silver ions, BTs show more persistent residual effects than chlorine and hyper-heating in water systems. BT efficiency increased with temperature. Like copper,silver ions, BT action is relatively slow. Significance and Impact of the Study: BT presents a new approach to containing water biofilms. BT action is not as rapid, but is more thorough than chlorine, and less caustic. BTs may also be more efficacious in hot water systems. At sub-minimum inhibition concentration levels, BTs uniquely inhibit bacterial exopolysaccharide, thereby retarding biofilm formation. Thus, the combination of bactericidal and residual effects may prevent slime build-up in hot water systems. [source] Preparation and characterization of silver containing chitosan fibersJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2007Yimin Qin Abstract Silver containing chitosan fibers were prepared by blending fine particles of a silver sodium hydrogen zirconium phosphate compound into the spinning solution. It was possible to distribute the silver containing particles in the chitosan fiber because of the high viscosity of the spinning solution and the small diameter of the particles. Because the silver ions are imbedded inside the sodium hydrogen zirconium phosphate complex, the chitosan fibers remain white in color without being oxidized by the silver ions. The release of silver ions from the silver containing chitosan fibers were studied by placing the fibers in contact with distilled water, solution A, and aqueous protein solutions. Results showed that the release of silver ions was low in water, while in solution A and protein solutions, the silver ions are activated through ion exchange and chelation. The silver ions can significantly enhance the antimicrobial properties of the chitosan fibers. Experimental results showed that when placed in contact with the silver containing chitosan fibers, the reduction in bacteria count can be more than 98%. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3622,3627, 2007 [source] Antibacterial activity of silver inorganic agent YDA fillerJOURNAL OF ORAL REHABILITATION, Issue 4 2004S. Ohashi summary, YDA filler is an antibacterial agent that is currently in commercial dental use. In this study, we attempted to determine whether it exerts an antibacterial effect on human saliva bacteria, and to determine whether it can be used in dental materials. CFUs in 1 mL stimulated human saliva were examined using blood agar and mitis salivarius agar after immersion, with or without YDA filler. The antibacterial effect was compared with that of Ketac-Silver. Dental materials containing 5% wt YDA filler were prepared for in vitro testing on S. mutans and A. viscosus. Furthermore, we examined the in vitro cytotoxicity of experimental MMA resin containing YDA filler on HeLa cells. Human saliva bacteria and mutans streptococci showed reduced viability following exposure to YDA filler after 12 h. The concentration of silver ions released by YDA filler was below 1 ppm after 12 h. Two tested strains showed reduced viability following exposure to dental materials containing YDA filler. In another experiment, MMA resin containing YDA filler did not show cytotoxicity on HeLa cells after 24- and 48-h exposure. Thus, YDA filler may help in the development of antibacterial dental materials, such as composite resin, glass,ionomer or temporary cement. [source] Polypeptide synthesis using an expressed peptide as a building block for condensation with a peptide thioester: Application to the synthesis of phosphorylated p21Max protein(1,101)JOURNAL OF PEPTIDE SCIENCE, Issue 9 2001Toru Kawakami Abstract An expressed peptide proved to be useful as a building block for the synthesis of a polypeptide via the thioester method. A partially protected peptide segment, for use as a C -terminal building block, could be prepared from a recombinant protein; its N -terminal amino acid residue was transaminated to an ,-oxoacyl group, the side-chain amino groups were then protected with t -butoxycarbonyl (Boc) groups, and, finally, the ,-oxoacyl group was removed. On the other hand, an O -phosphoserine-containing peptide thioester was synthesized via a solid-phase method using Boc chemistry. These building blocks were then condensed in the presence of silver ions and an active ester component. During the condensation, epimerization at the condensation site could be suppressed by the use of N,N -dimthylformamide (DMF) as a solvent. Using this strategy, a phosphorylated partial peptide of the p21Max protein, [Ser(PO3H2)2,11]-p21Max(1,101), was successfully synthesized. Copyright © 2001 European Peptide Society and John Wiley & Sons, Ltd. [source] Non-destructive Raman study of the glazing technique in lustre potteries and faience (9,14th centuries): silver ions, nanoclusters, microstructure and processingJOURNAL OF RAMAN SPECTROSCOPY, Issue 3 2004Philippe Colomban Abstract The oldest known nanotechnology dates back to the fabrication of the first lustre potteries. A lustre is a thin film formed just below the surface of medieval Islamic glazed potteries which contains silver and/or copper in the metallic and ionic form. Raman studies of the lustre films of different ceramics excavated from Fustât (near Cairo, Egypt, 11,12th century) or from the Silk Road (Termez, 13,14th centuries) showed that they associate many layers of different compositions (with or without cassiterite). Energy-dispersive spectroscopic analysis shows that all studied glazes are Ca- (and K)-rich, nearly free of Al silicates, with some addition of lead. Comparison is made with a copy of three-colour Tang ceramics made in Bassorah or Baghdad, in the 9th century, which is among the first known ,faiences', i.e. ceramics enamelled with an Sn-containing glaze. Surprisingly, Sn is not present in the form of a cassiterite (SnO2) precipitate but as a Ca,K-rich salt. Composition analysis and Raman spectra show that all glazes have been processed with similar technology. The distribution of elemental Ag and Cu is very heterogeneous in the lustre decor. The main Raman signature (50,100 cm,1 peaks) of the lustre film is assigned to Ag+ ions. The additional low-wavenumber features could be due to the Ag0 [or (Agn)m+] nanocluster modes. It is clear that the lustre colour arises from the combination of iridescence (diffraction) and absorption/diffusion. Raman criteria are proposed for a sample classification as a function of processing (cassiterite content, processing temperature). The glazing technique is discussed on the basis of experimental evidence and ancient potters' reports. Exothermic burning of acetate residus is proposed as the key step for the preparation of polychrome lustre. Copyright © 2004 John Wiley & Sons, Ltd. [source] Solubility of Silver and Palladium in BaTiO3JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2004Shao-Ju Shih Silver, palladium, and their alloys are frequently used as electrode materials for BaTiO3 (BT) based dielectrics. However, the electrodes and dielectrics usually are cofired at high temperatures, and silver and palladium can dissolve into the BT during cofiring. In the present study, the solubility of silver and palladium into BT after cofiring was determined. Three measurement techniques were used to determine solubility: chemical analysis, structural analysis, and dielectric analysis. The solubility of the silver in the BT was low, 450 ppm, after cofiring at 1290°C for 2 h in air. The diffusion distance of the silver ions into the BT was >5 ,m. The solubility of the palladium in the BT was even lower, 50 ppm at 1290°C, and the diffusion distance was ,1 ,m. The solubility of both the silver and the palladium in the BT decreased as the oxygen partial pressure of the sintering atmosphere decreased. These results demonstrated that both silver and palladium solutes act as acceptors for BT. [source] Photocatalytic Deposition of Silver Nanoparticles onto Organic/Inorganic Composite NanofibersMACROMOLECULAR MATERIALS & ENGINEERING, Issue 10 2006Sang Kyoo Lim Abstract Summary: In this work, silver nanoparticles were embedded in electrospun organic/inorganic composite nanofibers consisting of PAN and TiO2 through photocatalytic reduction of the silver ions in silver nitrate solutions under UV irradiation. The morphology and diameter of PAN/TiO2 composite nanofibers could be controlled by varying the initial contents of TiO2 in the spinning solution. From TEM images and UV-Vis spectra, it has been confirmed that monodisperse silver nanoparticles with a diameter of ,2 nm were deposited selectively upon the titania of the as prepared composite nanofibers. The amount of Ag nanoparticles embedded on composite nanofibers was greatly influenced by the amount of TiO2 in composite nanofibers, reflecting the role of titania as the inorganic stabilizer and photocatalyst. Morphology of silver nanoparticles embedded on PAN/TiO2 composite nanofibers. [source] Silver-Loaded Cotton/Polyester Fabric Modified by Dielectric Barrier Discharge TreatmentPLASMA PROCESSES AND POLYMERS, Issue 1 2009Mirjana Kosti Abstract The preparation of antimicrobial silver-loaded cotton/polyester fabrics has been carried out by DBD surface activation followed by silver sorption from aqueous silver nitrate solution. A series of DBD fabric treatments was performed in order to determine the most suitable experimental conditions for the fabric surface activation. The capillarity, silver ion uptake, and copper number were used to assess the surface changes on the fabrics. An effective process has been developed to obtain antimicrobial silver-loaded Co/PES fabrics. The antimicrobial activity of the silver-loaded fabrics against different pathogens was evaluated in vitro. The quantity of bonded silver ions is enough to develop desirable antimicrobial activity in the Co/PES fabrics. [source] Unusual Cu(I)/Ag(I) coordination of Escherichia coli CusF as revealed by atomic resolution crystallography and X-ray absorption spectroscopyPROTEIN SCIENCE, Issue 10 2007Isabell R. Loftin Abstract Elevated levels of copper or silver ions in the environment are an immediate threat to many organisms. Escherichia coli is able to resist the toxic effects of these ions through strictly limiting intracellular levels of Cu(I) and Ag(I). The CusCFBA system is one system in E. coli responsible for copper/silver tolerance. A key component of this system is the periplasmic copper/silver-binding protein, CusF. Here the X-ray structure and XAS data on the CusF,Ag(I) and CusF,Cu(I) complexes, respectively, are reported. In the CusF,Ag(I) structure, Ag(I) is coordinated by two methionines and a histidine, with a nearby tryptophan capping the metal site. EXAFS measurements on the CusF,Cu(I) complex show a similar environment for Cu(I). The arrangement of ligands effectively sequesters the metal from its periplasmic environment and thus may play a role in protecting the cell from the toxic ion. [source] Post-source decay matrix-assisted laser desorption/ionization mass spectrometric study of tetracyclic 2,3-dihydro-1,5-benzothiazepinesRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 12 2004Sándor Kéki The fragmentation behavior of six tetracyclic 2,3-dihydro-1,5-benzothiazepine derivatives cationized with protons and silver ions under post-source decay (PSD) matrix-assisted laser desorption/ionization (MALDI) conditions is reported. The protonated adduct ions decompose into several structurally important fragment ions, including substituted cyclopropane and benzohydrothiazole cations. Elimination of Ag and H and/or AgH from the silver-cationized adduct ions of these ([M+Ag]+) compounds was observed. It was also found that [M+Ag]+ produced silver-depleted fragment ions exclusively. Based on the PSD results a fragmentation pathway is proposed for the [M+H]+ and [M+Ag]+ precursor ions. Copyright © 2004 John Wiley & Sons, Ltd. [source] Ln3M1,,,,TX7, quasi-isostructural compounds: stereochemistry and silver-ion motion in the Ln3Ag1,,,,GeS7 (Ln = La,Nd, Sm, Gd,Er and Y; , = 0.11,0.50) compoundsACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2009Marek Daszkiewicz The crystal structures of the Ln3Ag1,,,,GeS7 (Ln = La,Nd, Sm, Gd,Er, Y; , = 0.11,0.50, space group P63) compounds were determined by means of X-ray single-crystal diffraction and the similarities among the crystal structures of all Ln3M1,,,,TX7 (space group P63; Ln , lanthanide element, M, monovalent element; T, tetravalent element and X, S, Se) compounds deposited in the Inorganic Crystal Structure Database (ICSD) are discussed. Substitutions of each element in Ln3M1,,,,TX7 result in a different structural effect. On the basis of the data deposited in the ICSD the large family of the Ln3M1,,,,TX7 compounds was divided into three groups depending on the position of the monovalent element in the lattice. This position determines what kind of stereoisomer is present in the structure, either the ++ enantiomer or the +, diastereoisomer. Since the silver ions can occupy a different position and the energy barriers between positions are low the ions can move through the channel. It was shown that this movement is not a stochastic process but a correlated one. [source] Selective extraction of polyunsaturated triacylglycerols using a novel ionic liquid precursor immobilized on a mesoporous complexing adsorbentBIOTECHNOLOGY PROGRESS, Issue 5 2009Patrisha J. Pham Abstract Mesoporous silica (SBA-15) synthesized by using Pluronic123 as the structure-directing template was functionalized by imidazolium-based ionic liquid precursors. Silver salts were then immobilized onto the supported ionic liquids using the incipient wetness impregnation technique. The separation of unsaturated species was achieved through the reversible and specific interaction between silver ions and carbon,carbon double bonds. This adsorbent was examined for the selective separation of polyunsaturated triacylglycerols (PUTAG) using High Pressure Liquid Chromatography (HPLC) with Evaporative Light Scattering Detection (ELSD) as the quantification methodology. AgBF4/SBA15·HPSiOEtIM·PF6 showed an adsorption capacity for linolenin of about 217 mg adsorbed/gram of sorbent. This adsorbent had good selectivity and a high capacity for the most highly unsaturated triacylglycerol when applied to a mixture of triacylglycerols with varying degrees of unsaturation. Consequently, a stepwise methodology was also developed to increase the recovery of the adsorbed components. This adsorbent retained its selectivity and capacity when recycled up to five times. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] | ||||||||||||||||