Metal-containing Compound Research Articles

Desiccation of the Extreme Thermoacidophile Metallosphaera sedula Grown on Terrestrial and Extraterrestrial Materials

Prokaryotes are among the most versatile organisms on Earth and their ability to adsorb metals for nutrient, energy or protection purposes can be noted in many different environments on our planet. The extreme thermoacidophilic archaeon Metallosphaera sedula is a metal-mobilizing archaeon capable of redox transformations during chemolithoautotrophic growth on diverse metal-bearing compounds. Examining the interfaces of this extreme metallophilic archaeon with various metal-bearing substrates of terrestrial and extraterrestrial origin, we have detected its selective preservation after desiccation. Cultivated on specific metal-bearing materials, e.g., tungsten-bearing scheelite, tungsten-bearing polyoxometalate, multimetallic waste products, and the NWA 1172 meteorite, cells of M. sedula can be preserved after dehydration, and therefore can potentially serve as a microbial fingerprint of the presence and/or activity of metal-transforming microorganisms. Preservation of desiccated M. sedula cells reported in this study has a discriminatory character, depending on the content and nature of the metal-containing compound used for cultivation of this metallophilic microorganism. The achieved preservation of dehydrated M. sedula cells facilitates our survivability studies with this desiccated microorganism during future space exposure experiments and under simulated space environmental conditions.

Graphene–Metal Nanoparticles for Enhancing Thermoelectric Power Factor

Chemical vapor deposition (CVD) grown graphene has been reported for a myriad of nanoelectronics and nanophotonics applications. However, CVD grown graphene suffers from low electrical conductivity due to the presence of multiple grain boundaries and intragranular defects. In order to improve its performance, graphene is often functionalized with other materials. In this work, graphene was hybridized with metallic nanoparticles (Au, Ag and Pt). Metal-containing inorganic compound solution was drop casted onto patterned graphene and was subsequently reduced by ultraviolet light. The hybridized graphene systems were explored as possible thermoelectric generators. It was shown that nanoparticles hybridized graphene displayed a significant decrease in sheet resistance. Amongst them, Au-graphene revealed an 80% decrease in sheet resistance. Ag- and Pt-graphene did not show any enhancement in the Seebeck effect while Au-graphene observed a 25% decline due to the thermal cooling effect. Overall, thermoelectric power factor was shown to increase by a factor of 2.96, 1.72 and 1.25 times for Au-graphene, Ag-graphene, and Pt-graphene, respectively.

Sample preparation strategies for bioinorganic analysis by inductively coupled plasma mass spectrometry

In this review the recent strategies of sample preparation are described and discussed for biomolecules separation/extraction for further metal(oid) or metal(oid)-containing compounds determination by inductively coupled plasma mass spectrometry (ICP-MS). Taking into account that ICP-MS can be considered a powerful analytical tool for the determination of metals and metaloids in animal and plant tissues, fluids and related samples, applications reported in the last fifteen years are described. This technique has been widely used in analytical procedures once it presents suitable sensitivity for trace analysis and could be coupled with several kinds of separation techniques such as liquid and gas chromatography, capillary and gel electrophoresis, among others. In this context, sample preparation is a crucial step in order to assure accurate results and non conventional sources of energy for sample preparation has been used, especially those related to ultrasound and microwaves. Thus, this review summarizes the sample preparation procedures regarding metal and metal-containing compound by ICP-MS, such as extraction and solubilization procedures, derivatization, pre-concentration, cleanup and also digestion for total metal analysis.

Phase transformations in tribosystems with metal-polymer components

The paper considers the study of the mechanism of nanophase transformations in metal-polymer composite materials based on thermoplastic matrices. It is shown that the reversible transition nanometal + polymer → metal-containing high-molecular compound, which results from the transformation of the adsorption bonds between the components into valent bonds, improves the performance characteristics of articles made of metal-polymer composites, including their wear resistance.

ELECTROCHEMISTRY Paper Li-ion batteries offer flexible power options

Ultrathin rechargeable lithium-ion batteries have been fabricated on a single sheet of paper, resulting in highly flexible and lightweight portable power sources, according to a study published in ACS Nano by Stanford University researchers (DOI: 10.1021/nn1018158). The advance may provide an integrated power solution for the developing field of paper-based electronics and lead to applications in “smart” packaging and radio-frequency sensing. To make the batteries, Stanford materials scientists Liangbing Hu, Hui Wu, Yi Cui, and coworkers coated a solid support with a thin film of carbon nanotubes and deposited a film of a metal-containing lithium compound on top of the nanotubes. Then the team deposited the double-layer films on both sides of ordinary paper. In that design, the lithium layers function as battery electrodes and the nanotube films serve as current collectors. The paper is the electrode separator and also serves as a mechanical support. The new batteries, which are just 300 μm thick, are ...

Study of the reaction mechanism of the copper chelate with DGEBA using DSC

The reaction mechanism of metal-containing and complex compound with epoxy oligomer of diglycidyl ether of bisphenol A (DGEBA) was studied using dynamic DSC technique. It is shown that cure reaction of the epoxy oligomers with copper acetate proceeds at two stages: through coordination of cation with the epoxy group, and through ionic polymerization at high temperatures. Mechanism of curing of DGEBA with copper chelate depends on equilibrium process of dissociation of the chelate which, in turn, depends not only on temperature of curing but also on concentration of the hardener. At the dissociation temperature of the hardener, polymerization proceeds according to ionic mechanism. Hardening of the epoxy oligomers due to interaction of epoxy groups with unconnected amine groups predominate at higher temperatures or at higher concentrations of the hardener. At low temperatures and small concentrations of the hardener, polymerization proceeds according to catalytic ionic mechanism.

EXTRACTION OF SOLUBLE PHOSPHORUS FROM SWINE WASTEWATER

Manure phosphorus (P) in excess of the assimilative capacity of land available on farms is an environmental concern often associated with confined livestock production. A wastewater treatment process was developed for removal of phosphorus from livestock wastewater. It includes nitrification of wastewater to remove ammonia and carbonate buffers, and increasing the pH of the nitrified wastewater by adding an alkaline earth metal-containing compound to precipitate phosphorus. Since ammonia nitrogen has been mostly converted to nitrate, increased pH does not result in significant gaseous nitrogen loss. The amount of phosphorus removed, and consequently the N:P ratio of the effluent, can be adjusted in this process to match specific crop needs or remediate sprayfields. In addition to the phosphorus removal aspect, the high pH used in the process destroys pathogens in liquid swine manure. The final product is calcium phosphate, which has the potential to be reused as fertilizer or processed to produce phosphate concentrates.

Nano-structured metal-containing polymer precursors for high temperature non-oxide ceramics and ceramic fibers—syntheses, pyrolyses and properties

Nano-structured metal-containing ceramic polymer precursors have a potential for progress in the field of polymer-derived ceramics. In this paper the synthesis and characterization of nano-metallopolycarbosilanes (nMPCS) and their transformation into ceramic materials are reported. The formation of metal nano-particles via fast thermolysis of metal- containing compounds in polymer solution or melt previously developed by the authors was applied to preceramic polymers. Tetrabenzyltitanium, tetrabenzylzirconium, bis(cyclopentadienil)dichloride-titanium and zirconium as well as tetrachlorides of these metals and tetrakis(diethylamino)zirconium were used for the introduction of metal nano-particles. The products were characterized by thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC), differential-thermal analysis (DTA), gel-penetration (GP)-chromatography, X-ray diffraction (XRD), scanning electron microscopy (SEM) and other special analyses. The results of these studies may be useful for the fabrication of non-oxide ceramic fibers, interphase coatings and high temperature ceramic matrix composite (HT-CMC) matrices. Cp2ZrCl2 and Zr[N(C2H5)2]4 provided nano-particles with diameters of 2–4 nm and turned out to be the most suitable compounds for the preparation of ceramic matrices. Besides, they open a new way of oxygen-free curing. Coreless fibers were obtained from nZrPCS with up to 3 mass% of metal. Future investigations will be focused on optimization of the oligocarbosilanes used as starting materials and the development of less reactive polycarbosilane (PCS)–metal-containing compound (MCC) systems.

Preferential supporting of platinum particles on pore surface using a polymer blend technique

We have proposed a novel preparation method of porous carbon fiber without an activation process by using a polymer blend technique [1]. A polymer blend consisting of two kind of polymers with (carbon precursor polymer) and without (pore forming polymer) residual carbon after heating in an inert atmosphere is subjected to spinning, stabilizing and finally carbonizing. Pores are formed in the carbon fiber derived from the carbon precursor polymer after removing the pore forming polymer. Here the pore volume and the pore size will be controlled by the blending ratio of both polymers and the blending texture, respectively. When a pore forming polymer mixed with a metal-containing compound in advance is used, the metal is expected to be left preferentially on the pore surface after removal of the pore forming polymer. We have already tried to support Pt particles by using a polymer blend consisting of phenolformaldehyde polymer as a carbon precursor polymer and polyvinylbutyral as a pore forming polymer, but the result was not as good as we expected [2]. The present work was undertaken to determine whether the idea is essentially reasonable or not. A novolac-type phenol-formaldehyde polymer (abbreviation: PF) and maleinic acid-modified low density polyethylene (abbreviation mPE) were used as a carbon precursor polymer and a pore forming polymer, respectively. Pt(II)-acetylacetonate ([Pt(C5H7O2)2], abbreviation: Pt-acac) was used as a precursor compound of Pt particle. We suppose when the Pt precursor compound has no chemical affinity with a pore forming polymer, it may diffuse into the carbon precursor polymer from the pore forming polymer during the mechanical blending process under heating, leading to incorporation of Pt particles in the resulting carbon matrix. This is why mPE was used instead of conventional PE. Another reason is a high spinnability of mPE. mPE was dissolved in benzene thoroughly together with 1.6wt% of Pt-acac, followed by evaporation of benzene under a reduced pressure to obtain mPE containing the finely dispersed Pt-acac (abbreviation: PtmPE). The addition amount of 1.6wt% corresponds to 0.7wt% of Pt in the finally resulting porous carbon fiber according to the calculation using the TG data shown in Fig. 1, which will be stated below. Pt-mPE was ground into particles with diameter less than ca.1 mm and was blended mechanically with PF particles of several mm in diameter at 110–120 ◦C with a Laboratory Mixing Extruder Model CS-194AV (Toyo Seiki Co. Ltd.). The

Antisecretory and Antiulcer Effects of Ebselen, a Seleno-Organic Compound, in Rats

The effects of ebselen (2-phenyl-1,2-benzisoselenazol-3(2H)-on), a metal-containing organic compound, on gastric secretion and gastric ulceration were examined in rats. Intraduodenal ebselen (30 to 300 mg/kg) significantly and dose-dependently inhibited gastric secretion in pylorus-ligated rats. Both aspirin- and water-immersion restraint stress-induced ulcers were significantly prevented by oral administration of ebselen at doses equivalent to the antisecretory doses. These results indicate that the antisecretory effect of ebselen underlies its antiulcer effect in these models.

Immunomodulatory activity and non-specific suppressor cell generation by spirogermanium in murine and rat models of cell-mediated immunity

Spirogermanium (SG) is a metal-containing compound reported to have antitumor, antiarthritic, antimalarial and immunoregulatory activity. In this study we have demonstrated that treatment of mice and rats with spirogermanium results in an inhibition of autoimmune disease and cell-mediated immune (CMI) responses. Prophylactic administration of SG inhibited the development of adjuvant-induced arthritis and the DTH response to purified protein derivative (PPD) in Lewis strain rats. SG treatment was also able to alleviate the symptoms of experimental autoimmune encephalomyelitis (EAE) induced in Lewis rats. In two strains of mice, BDF1 and C57B1/6, the DTH response to sheep red blood cells could be suppressed by intraperitoneal (i.p.) administration of SG. The spleens of both mice and rats that have been treated with this drug contain suppressor cells which inhibit the response of normal cells to concanavalin A (Con A) and the mixed lymphocyte reaction. In addition, the generation of cytotoxic T cells (CTL) in the murine MLR is abrogated in the presence of these suppressor cells. The suppressor cells were radiation-resistant (2000 rad), indomethacin-insensitive and were not depleted by treatment with anti-Thy-1.2 antiserum plus complement. These results suggest that SG modulates cell-mediated immune responses in vivo by the induction of non-specific suppressor cells.

Suppressor cell induction by the anticancer drug spirogermanium

Spirogermanium is a metal-containing compound reported to have antitumor, antiarthritic, antimalarial and immunoregulatory activity. In this study we have demonstrated that spirogermanium inhibited antibody sytnhesis to sheep red blood cells in BDF1 mice in vivo. Spleen cells from these treated mice were unable to respond to this antigen in vitro, and suppressed both the antibody response of normal cells to SRBC and the mitogenic response of normal cells to Concanavalin A in co-culture assays. The cells responsible for this suppression did not belong to the T cell lineage since treatment with anti-Thy-1.2 antiserum and complement did not abrogate the suppression. The suppressor cells were found to be radiation resistant and nylon wool adherent. Plastic adherence or passage over Sephadex G10 partially removed the suppression indicating the contribution, at least in part, of a suppressor macrophage. The plastic non-adherent population of cells also contained suppressor cells which were detected following anti-thy-1.2 treatment and selection by panning on anti-IgG coated plates. Fluorescent antibody and flow cytometry technology showed the population of suppressor cells to be 90% immunoglobulin positive, indicative of a B cell lineage.

Zeolite-supported metal catalysts for Fischer-Tropsch reactions: I. A new preparation method

A new preparation method of zeolite-supported metal catalysts is described. The method is based on the reaction between a metal-exchanged zeolite and an anionic, metal-containing coordination compound, specifically a water-soluble, metal cyanide complex. The reaction product is an insoluble compound distributed throughout the zeolite. Subsequent reduction in hydrogen results in finely dispersed metal in the zeolite. The method described can be used in the preparation of single or polymetallic catalysts. A single metal catalyst is obtained when the metal in the exchanged zeolite is the same as the one in the coordination compound. If the metals are different, a bimetallic catalyst will result. The method can be used for the preparation of a variety of zeolite-supported metal catalysts. In this paper the preparation of catalysts to be used in Fischer-Tropsch reactions is described. The materials prepared have been characterized by infrared and TGA DTA methods.

Metal-containing organic high molecular compound reinforced with particulate organic or inorganic material : Sato, H. et al (Mitsubishi Rayon Co Ltd, Tokyo, Japan) US Pat 3 920 605 (18 November 1975)

Metal-containing organic high molecular compound reinforced with particulate organic or inorganic material : Sato, H. et al (Mitsubishi Rayon Co Ltd, Tokyo, Japan) US Pat 3 920 605 (18 November 1975)