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The silatrane hydride compound, [N[([CH.sub.2][CH.sub.2]O).sub.3]]SiH, reacts with [CO.sub.2] in the presence of the [tris(2-pyridylthio)-methyl]zinc hydride complex, [Tptm]ZnH, to afford the silyl formate and methoxide derivatives, [N[([CH.sub.2][CH.sub.2]O).sub.3]][SiO.sub.2]CH and [N[([CH.sub.2][CH.sub.2]O).sub.3]][SiOCH.sub.3]. The molecular structure of [N[([CH.sub.2][CH.sub.2]O).sub.3]][SiO.sub.2]CH has been determined by X-ray diffraction, thereby demonstrating that the formate ligand adopts a distal conformation in which the uncoordinated oxygen atom resides with a trans-like disposition relative to silicon. Density functional theory calculations indicate that the atrane motif of [N[([CH.sub.2][CH.sub.2]O).sub.3]][SiO.sub.2]CH is flexible, such that the energy of the molecule changes relatively little as the Si***N distance varies over the range 2.0-3.0 A. Key words: hydrosilane, [CO.sub.2], silyl formate, atrane, zinc. Le compose d'hydrure de silatrane [N[([CH.sub.2][CH.sub.2]O).sub.3]]SiH reagit avec le [CO.sub.2] en presence du complexe d'hydrure de [tris[(2pyridylthio)methyl]zinc, [Tptm]ZnH, pour former les derives silyles formate et methoxy N([CH.sub.2][CH.sub.2]O).sub.3]][SiO.sub.2]CH et [N[([CH.sub.2][CH.sub.2]O).sub.3]][SiOCH.sub.3]. Nous avons determine la structure moleculaire du compose [N[([CH.sub.2][CH.sub.2]O).sub.3]][SiO.sub.2]CH par diffraction des rayons X, et avons montre ainsi que le ligand formate adopte une conformation distale dans laquelle l'atome d'oxygene non coordonne se trouve dans une configuration pseudo-trans par rapport a l'atome de silicium. Les calculs de theorie de la fonctionnelle de la densite indiquent que le motif atrane du compose [N[([CH.sub.2][CH.sub.2]O).sub.3]][SiO.sub.2]CH est flexible, de sorte que l'energie de la molecule change relativement peu lorsque la distance Si***N varie dans l'intervalle de 2,0 a 3,0 A. [Traduit par la Redaction] Mots-cles : hydrosilane, [CO.sub.2], formate de silyle, atrane, zinc., Introduction There is currently much interest in developing the use of [CO.sub.2] as a renewable [C.sub.1] source for the synthesis of organic chemicals, which also pertains to efforts in countering [...]

Two manganese(III) compounds were studied as catalysts for the reaction of carbon dioxide with propylene oxide, styrene oxide, and cyclohexene oxide, and formed cyclic carbonate products selectively under solvent free conditions in the presence of an ionic co-catalyst such as TBAB or PPNCl. Variable temperature kinetic studies allowed the activation energy for propylene carbonate formation to be determined (64 kJ [mol.sup.-1]). The catalysts showed good stability in these reactions and overall turnover numbers (TON) of up to 6000 were observed. The complexes showed low activity for the aerobic oxidation of 4-methyoxybenzylalcohol to the corresponding aldehyde, achieving up to 40% conversion in 72 h. However, near quantitative conversion of 1,2-diphenyl-2-methoxyethanol to provide up to 90% yield of benzaldehyde could be achieved over the course of 5 days. Both complexes showed similar reactivity in the two catalytic processes, and this is likely due to the weakly coordinating nature of the pendant donor within the tetradentate ligand. Key words: manganese, oxidation catalysis, NO ligand, carbon dioxide, C-C cleavage. Nous avons etudie deux composes de manganese(III) comme catalyseurs de la reaction entre le dioxyde de carbone et l'oxyde de propylene, l'oxyde de styrene ou l'oxyde de cyclohexene. Cette reaction a donne lieu a la formation selective de carbonates cycliques dans des conditions sans solvant, en presence d'un cocatalyseur ionique tel que le TBAB ou le PPNCl. Des etudes cinetiques a differentes temperatures ont permis de determiner l'energie d'activation pour la formation du carbonate de propylene (64 kJ mol[.sup.1]). Les catalyseurs ont montre une bonne stabilite dans ces conditions de reaction. En effet, nous avons observe jusqu'a 6 000 cycles catalytiques. Ces complexes ont montre une faible activite pour l'oxydation aerobie du 4methoxybenzylalcool en l'aldehyde correspondant, la conversion atteignant 40 % en 72 h. Cependant, ils ont montre une conversion presque quantitative du 1,2diphenyl-2-methoxyethanol, qui a permis d'obtenir le benzaldehyde correspondant dans un rendement atteignant 90 % en 5 jours. Les deux complexes ont montre une reactivite similaire dans les deux processus catalytiques, et cela s'explique probablement par la faible coordination du groupe donneur appendiculaire que porte le ligand tetradentate. [Traduit par la Redaction] Mots-cles: manganese, catalyse d'oxydation, ligand NO, dioxyde de carbone, clivage C-C., Introduction Amino-phenolate ligands are easily tailored in terms of their electronic and steric properties, and with their combination of donors, they are readily suited for coordination with metals from across [...]

Processing of a high glass transition ([T.sub.g]) polymer such as polyethersulfone (PES; [T.sub.g] = 225[degrees]C) poses a challenge as it requires high processing temperatures or sometimes toxic solvents. In this work, we report of a facile process using superheated water (s[h.sub.[H.sub.2]]O) and supercritical carbon dioxide (scC[O.sub.2]) co-media. PES solids were foamed in the scC[O.sub.2]/sh[H.sub.2]O co-media or scC[O.sub.2] alone in a batch process at different temperatures. The scC[O.sub.2]/sh[H.sub.2]O produced a synergistic effect and achieved PES foams even at processing temperatures as low as 85[degrees]C below the nominal [T.sub.g]; whereas, scC[O.sub.2] alone required higher processing temperatures. Moreover, the scC[O.sub.2]/sh[H.sub.2]O comedia produced highly porous PES foams that were at least 23% higher in porosity than what was obtained using scC[O.sub.2] alone. In addition, the scC[O.sub.2]/sh[H.sub.2]O produced open cell foams at some processing conditions; whereas, scC[O.sub.2] produced closed cell morphologies. Since both C[O.sub.2] and [H.sub.2]O are innocuous, this approach has potential for use in the preparation of ultrafiltration membranes, which currently require the use of toxic solvents for their fabrication by way of the phase inversion process. Moreover, the use of scC[O.sub.2]/sh[H.sub.2]O is a cost-effective approach for the processing of high [T.sub.g] polymers at significantly lower temperatures., INTRODUCTION Polyethersulfone (PES), by virtue of its high mechanical strength (Young's modulus >2.5 GPa), chemical stability and thermal stability, is notable for a number of high performance and load bearing [...]

Soil organic matter (SOM) quantity and quality can be directly altered by climate, and SOM has been proposed as both a significant source and sink of carbon dioxide. To understand the factors that influence SOM, the present study focuses on the relationship between precipitation and soil physical and chemical properties along a rainfall-vegetation gradient in a seasonally dry tropical forest in the Western Ghats, southern India. Soil pH decreased with increasing rainfall, but soil organic carbon (SOC) and nitrogen (N) slightly increased. Rainfall had strong positive correlations with standing litter (Pearson's r=0.85), clay content (r=0.69) and recalcitrant organic matter (r=0.73) (all P Additional keywords: density fractionation, Mudumalai, soil carbon, soil texture, thermal stability, vegetation types., Introduction Forest soils serve as a large pool of carbon (C). The soil's ability to store C differs with biotic (Hagen-Thom etal. 2004; Vesterdal et al. 2008) and abiotic factors [...]

We investigated whether calcium chloride (CaCl.sub.2), a supplementary additive in carbon dioxide (CO.sub.2) absorbents, could affect carbon monoxide (CO) production caused by desflurane degradation, using a Japanese alkali-free CO.sub.2 absorbent Yabashi Lime.sup.®-f (YL-f), its CaCl.sub.2-free and 1% CaCl.sub.2-added derivatives, and other commercially available alkali-free absorbents with or without CaCl.sub.2. The reaction between 1 L of desflurane gas (3-10%) and 20 g of desiccated specimen was performed in an artificial closed-circuit anesthesia system for 3 min at 20 or 40 °C. The CO concentration was measured using a gas chromatograph equipped with a semiconductor sensor detector. The systems were validated by detecting dose-dependent CO production with an alkali hydroxide-containing CO.sub.2 absorbent, Sodasorb.sup.®. Compared with YL-f, the CaCl.sub.2-free derivative caused the production of significantly more CO, while the 1% CaCl.sub.2-added derivative caused the production of a comparable amount of CO. These phenomena were confirmed using commercially available absorbents AMSORB.sup.® PLUS, an alkali-free absorbent with CaCl.sub.2, and LoFloSorb[TM], an alkali-free absorbent without CaCl.sub.2. These results suggest that CaCl.sub.2 plays an important role in preventing CO generation caused by desflurane degradation with alkali hydroxide-free CO.sub.2 absorbents like YL-f., Author(s): Takahiro Ando [sup.1] , Atsushi Mori [sup.2] , Rie Ito [sup.1] , Kimitoshi Nishiwaki [sup.1] Author Affiliations: (1) Department of Anesthesiology, Nagoya University Graduate School of Medicine, 0000 0001 [...]

Author(s): Francisco Juli-Hernndez [1]; Toni Moragas [1]; Josep Cornella [1]; Ruben Martin (corresponding author) [1, 2] Catalytic carboncarbon bond formation has enabled the streamlining of synthetic routes when assembling complex [...]

Abstract: Global warming is the major environmental issue caused by greenhouse gases, especially C[O.sub.2]. This demands urgent action to reduce or offset C[O.sub.2] emission from power plants, which could be [...]

The copper-doped gold nanowires (4 nm in diameter) were produced by the novel technique based of laser ablation of Au-Cu alloy inside superfluid helium. The principle of the method is using the quantized vortices as the 1D template for the condensation of the ablation products into thin threads. The nanowires were applied as the catalyst in CO oxidation with oxygen. The activity of Au-Cu nanowires deposited on glass filters was compared with that for monometallic and bimetallic Au and Cu particles (3-8 nm in diameter) deposited on alumina by traditional deposition-precipitation and impregnation techniques. The apparent activation energies of the reaction (Ea) were 95 and 98, 150, and 147 kJ/ mol for Au-Cu nanowires and Au-Cu, Au, and Cu particles, respectively. During running-in of the Au-Cu nanowire-based catalyst, Ea decreased to 20 kJ/mol and retained at this level in the subsequent cycles of lowering and raising the reactor temperature. Keywords Nanowires * Au * Cu * Au-Cu * CO * Oxidation, Introduction For a long time, gold had been regarded as a very stable and catalytically inert metal until Haruta et al. found the surprisingly high activity of supported gold nanoparticles [...]

In this study, capture of C[O.sub.2] and [H.sub.2]S from natural gas mixture using porous polymeric membranes has been investigated numerically to assess the capacity of a novel absorbent, di-isopropanol amine (DIPA), in C[O.sub.2] removal. Diffusion of acid gases through porous polymeric membranes was simulated by employing CFD techniques and considering a gas feed stream, a porous membrane and a reaction medium. For solving conservation equations, finite element method was applied to calculate the rate of C[O.sub.2] and [H.sub.2]S absorption in the membrane. The type of membrane in this work is a hollow-fiber module. According to the modeling results, a high [H.sub.2]S removal can be achieved by DIPA absorber. Moreover, C[O.sub.2] was captured from natural gas in an efficient manner in low gas/liquid flow rates., INTRODUCTION Reduction of greenhouse gas effects has been a subject of great interest during recent years. It can be achieved by removing acid gases from gas streams regarding to this [...]

We investigated the crystallization growth of isotactic polypropylene (PP)/clay phase-separated microcomposites under carbon dioxide ([CO.sub.2]) by in situ observation with a specially designed high-pressure visualized cell. The number density of the spherulite was larger and the size of the spherulite filled in the whole space was smaller in the PP/clay microcomposites than those in the neat PP, indicating nucleation effect of clay on the crystallization of PR The increase of the number density of the spherulite by addition of clay was much larger under [CO.sub.2] than that under air at ambient pressure, suggesting that the nucleation effect of clay is enhanced under [CO.sub.2]. Microscopic observation and small angle X-ray scattering measurement revealed that lamellae grow from the surface of the clay tactoids, and the lamellae and lamellar stacks arrange irregularly due to the growth of lamellae from the irregular shaped clay in different directions. POLYM. ENG. SCI., 52:2228-2236, 2012. © 2012 Society of Plastics Engineers, INTRODUCTION Isotactic polypropylene (PP) is one of the most widely used crystalline. polymers. The addition of inorganic tillers to PP has been studied as a means of providing functional roles [...]

When the copolymerization of vinylidene fluoride (VDF) and hexafluoropropylene (HFP) is carried out in supercritical carbon dioxide (scC[.sub.2]) under heterogeneous conditions, the reaction occurs both in the continuous C[O.sub.2]-rich phase and in the dispersed polymer-rich phase. The two phases being characterized by different values of reactant concentrations and kinetic parameters, one would expect that the reaction kinetics is affected by the polymer phase holdup in the reactor. However, the reaction rate is almost insensitive to the amount of produced polymer, at least at specific reaction conditions. This apparent contradiction is discussed and clarified in this paper by a series of comparative simulations carried out using different models, accounting for the reaction in one single phase (one-locus) or in two phases (two-loci). This analysis provides general procedures which can be used to design experimental investigations able to identify the number of reaction loci for a given heterogeneous polymerization system. POLYM. ENG. SCI., 51:2093-2102, 2011. ©2011 Society of Plastics Engineers, INTRODUCTION Polymerization reactions carried out in fluids that are immiscible with the forming polymer are heterogeneous processes. In these systems the reaction can occur in the fluid continuous phase, in [...]

The solubility of [CO.sub.2] in native potato starch (NPS) and potato starch acetate (SA) at two different temperatures (50°C and 120°C) and various pressures (up to 25 MPa) was determined using a magnetic suspension balance. Within the experimental window, a maximum solubility of 31 mg [CO.sub.2]/[g.sub.sample] for NPS and 79.4 mg [CO.sub.2]/[g.sub.sample] for SA was obtained. The [CO.sub.2] sorption behavior is highly depending on the temperature and pressure. The solubility data were modeled with the Sanchez Lacombe equation of state (S-L EOS). The swelling ([S.sub.w]) values, as predicted using the S-L EOS, were relatively small and a maximum value of 6.1% was obtained for SA at 25 MPa and 120°C. POLYM. ENG. SCI., 51:28-36, 2011, [C] 2010 Society of Plastics Engineers, INTRODUCTION The unique properties of supercritical fluids (e.g., gaslike diffusivity and liquid-like density) have rendered supercritical technology a very attractive alternative for conventional ones and have led to a boost [...]

Because solar energy is available in large excess relative to current rates of energy consumption, effective conversion of this renewable yet intermittent resource into a transportable and dispatchable chemical fuel may ensure the goal of a sustainable energy future. However, low conversion efficiencies, particularly with C[O.sub.2] reduction, as well as utilization of precious materials have limited the practical generation of solar fuels. By using a solar cavity-receiver ==reactor, we combined the oxygen uptake and release capacity of cerium oxide and facile catalysis at elevated temperatures to thermochemically dissociate C[O.sub.2] and [H.sub.2]O, yielding CO and [H.sub.2], respectively. Stable and rapid generation of fuel was demonstrated over 500 cycles. Solar-to-fuel efficiencies of 0.7 to 0.8% were achieved and shown to be largely limited by the system scale and design rather than by chemistry. 10.1126/science.1197834

A novel chromatographic separation method is introduced which employs water (saturated with [CO.sub.2]) as a stationary phase and [CO.sub.2] (saturated with water) as a mobile phase. Since water and [CO.sub.2] have little miscibility, conditions can be attained that create a stationary phase of water lining the inside of an uncoated stainless steel capillary. Because altering temperature and pressure can change both the density of the mobile phase and the polarity of the stationary phase, these experimental parameters offer good flexibility for optimizing separations and allow for different gradient programmed separation options. Further, since this method is free of organic stationary and mobile phase components, it is environmentally compatible and allows the use of universal flame ionization detection. This system offers very good sample capacity, peak symmetry, and retention time reproducibility (~1% RSD run-to-run, ~4% RSD day-to-day). Analytes such as alcohols, carboxylic acids, phenols, and tocopherols are employed to investigate this relatively inexpensive and robust method. As an application, the system is used to quantify ethanol in alcoholic beverages and biofuel and to analyze caffeine levels in drinks. In all cases, quantitative results are obtained with quick throughput times and often little need for sample preparation. 10.1021/ac1018793

In the present work, a numerical analysis has been presented to show the variations in flame structure, flame radiation, and formations of soot and NO in methane-air laminar nonpremixed flames with different C[O.sub.2] dilutions of fuel. It is observed that the flame length reduces as the dilution of the fuel stream by C[O.sub.2] increases while maintaining constant fuel jet velocity at the burner tip. However, the flame length remains almost unchanged with different blends of C[H.sub.4] and C[O.sub.2] if the burner loading (i.e., fuel flow rate x Cheating value of fuel) is kept constant. Both soot and NO formations decrease monotonically when the C[O.sub.2] fraction in the fuel is increased. The radiation from the flame also decreases when C[O.sub.2] dilution of the fuel is increased, particularly, when the fuel jet velocity is maintained constant. [DOI: 10.1115/1.4001809] Keywords: nonpremixed flame, flame structure, C[O.sub.2] dilution, soot, NO

The use of carbon dioxide as a renewable and environmentally friendly source of carbon in organic synthesis is a highly attractive approach, but its real world applications remain a great challenge. The major obstacles for commercialization of most current protocols are their low catalytic performances, harsh reaction conditions, and limited substrate scope. It is important to develop new reactions and new protocols for C[O.sub.2] transformations at mild conditions and in cost-efficient ways. Herein, a copper-catalyzed and copper--N-heterocyclic carbene-cocatalyzed transformation of C[O.sub.2] to carboxylic acids via C-H bond activation of terminal alkynes with or without base additives is reported. Various propiolic acids were synthesized in good to excellent yields under ambient conditions without consumption of any organometallic or organic reagent additives. This system has a wide scope of substrates and functional group tolerances and provides a powerful tool for the synthesis of highly functionalized propiolic acids. This catalytic system is a simple and economically viable protocol with great potential in practical applications. doi/ 10.1073/pnas.1010962107

Land use and management practices may influence plant C inputs and soil C[O.sub.2] emission. We evaluated the effect of a combination of irrigation, tillage, cropping system, and N fertilization on plant biomass C, soil temperature and water content at the 0- to 15-cm depth, and C[O.sub.2] emission in a sandy loam soil from April to October, 2006 to 2008, in western North Dakota. Treatments were two irrigation practices (irrigated and unirrigated) and six cropping systems (conventional-tilled malt barley [Hordeum vulgare L.] with N fertilizer [CTBFN], conventional-tilled malt barley with no N fertilizer [CTBON], no-tilled malt barley-pea [Pisum sativum L.] with N fertilizer [NTB-PN], no-tilled malt barley with N fertilizer [NTBFN], no-tilled malt barley with no N fertilizer [NTBON], and no-tilled Conservation Reserve Program [NTCRP]). Plant biomass C was greater in NTBFN than in NTBON in 2006 and 2007 but was greater in NTB-PN than in CTBON, NTBON, or NTCRP in 2008. Soil temperature was greater hut water content was lower in NTCRP than in CTBFN and NTBFN. Soil C[O.sub.2] flux peaked immediately following heavy rain or irrigation (> 15 mm). Total C[O.sub.2] flux from April to October was greater in the irrigated than in the unirrigated practice and greater in NTCRP than in annual cropping systems. Soil C[O.sub.2] emission was probably related more to soil temperature and water content or tillage than to aboveground plant C input. Because of reduced C[O.sub.2] flux compared with CTBON and NTCRP but similar biomass yield as NTBFN and CTBFN, NTB-PN may be used to reduce C[O.sub.2] emission from croplands in the northern Great Plains. doi: 10.2136/sssaj2009.0447

Early age carbonation curing of slag-cement concrete was investigated to assess the feasibility of binding C[O.sub.2] in slag-cement building products while improving their short-term and long-term performances. Four binder types were compared: an ordinary portland cement; an 85/15 slag cement: a 75/25 slag blend; and a 50/50 slag blend. A 2-h carbonation-curing treatment allowed concretes to bind 8-10% C[O.sub.2] by mass of binder and attain as much as 82% of the 24-h hydration strength. The subsequent strength development of carbonated concrete was slower in the first 24 h possibly due to the carbonate buildup, but it was comparable to the conventionally hydrated concrete after 28 days. The carbonated concrete was shown to have a fracture toughness comparable to that of the hydrated concrete. The freeze/thaw durability of the concrete in deicing salt solution was vastly improved by the carbonation treatment. The pH of the carbonated concrete was reduced but was still above the threshold level required for the passivation of iron. The use of slag in carbonation curing is beneficial to strength gain, shrinkage reduction, and deicing salt resistance. DOI: 10.1061/(ASCE)MT.1943-5533.0000018 CE Database subject headings: Cement; Concrete; Mechanical properties; Durability; Carbon dioxide; Carbonation. Author keywords: Carbonation curing; Slag cement; Concrete; Mechanical properties; Durability; Carbon dioxide binding.

The knock and combustion characteristics of CO, [H.sub.2], C[H.sub.4], and their mixtures were determined experimentally in a variable compression ratio spark ignition (SI) cooperative fuel research (CFR) engine. The significant effects of gaseous fuel mixtures containing [H.sub.2] in enhancing the combustion and oxidation process of C[H.sub.4] were examined. The unique combustion characteristics of CO in dry air and its distinct performance in mixtures with H-containing fuels were investigated. The addition of a simulated synthesis gas (2[H.sub.2] + CO) to C[H.sub.4] was found to enhance the combustion process of the resulting mixture and lowers its knock resistance. The effectiveness of such an addition is slightly weaker than that of a comparable [H.sub.2] addition but much stronger than that with CO addition only. A predictive model with detailed kinetic chemistry was used successfully to simulate SI engine operation fuelled with C[H.sub.4], [H.sub.2], CO, and their mixtures. The predicted engine performance and knock limits of C[H.sub.4], [H.sub.2], CO, and their mixtures agree well with experimental data with the exception around pure CO operation in dry air with the presence of small amounts of C[H.sub.4] or [H.sub.2]. A remedial approach to improve the prediction of the knock limits of fuel mixtures containing mainly CO with a small amount of H-containing fuels such as [H.sub.2] and C[H.sub.4] was proposed and discussed. [DOI: 10.1115/1.3155795]