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Sample records for acyl-coa dehydrogenation deficiency

  1. Fuel utilization in patients with very long-chain acyl-coa dehydrogenase deficiency

    DEFF Research Database (Denmark)

    ØRngreen, Mette C; Nørgaard, Mette; Sacchetti, Massimo

    2004-01-01

    Fuel utilization in two adult patients with the myopathic form of very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency and five healthy subjects was investigated with stable isotopes during exercise at 50% of VO2max. The findings indicate that residual VLCAD activity in the patients...

  2. The ETFDH c.158A>G Variation Disrupts the Balanced Binding of ESE and ESS Proteins Causing Missplicing and Multiple acyl-CoA Dehydrogenation Deficiency

    DEFF Research Database (Denmark)

    Olsen, Rikke K J; Brøner, Sabrina; Sabaratnam, Rugivan

    2013-01-01

    Multiple acyl-CoA dehydrogenation deficiency is a disorder of fatty acid and amino acid oxidation caused by defects of electron transfer flavoprotein (ETF) or its dehydrogenase (ETFDH). A clear relationship between genotype and phenotype makes genotyping of patients important not only diagnostica......Multiple acyl-CoA dehydrogenation deficiency is a disorder of fatty acid and amino acid oxidation caused by defects of electron transfer flavoprotein (ETF) or its dehydrogenase (ETFDH). A clear relationship between genotype and phenotype makes genotyping of patients important not only......-down of nuclear proteins, we show that the c.158A>G variation increases the strength of a preexisting exonic splicing silencer (ESS) motif UAGGGA. This ESS motif binds splice inhibitory hnRNP A1, hnRNP A2/B1, and hnRNP H proteins. Binding of these inhibitory proteins prevents binding of the positive splicing...

  3. Transient multiple acyl-CoA dehydrogenation deficiency in a newborn female caused by maternal riboflavin deficiency

    DEFF Research Database (Denmark)

    Chiong, M A; Sim, K G; Carpenter, K

    2007-01-01

    A newborn female presented on the first day of life with clinical and biochemical findings consistent with multiple acyl-CoA dehydrogenase deficiency (MADD). Riboflavin supplementation corrected the biochemical abnormalities 24 h after commencing the vitamin. In vitro acylcarnitine profiling...

  4. Decarbonylation and dehydrogenation of carbohydrates

    Science.gov (United States)

    Andrews, Mark A.; Klaeren, Stephen A.

    1991-01-01

    Carbohydrates, especially aldose or ketose sugars, including those whose carbonyl group is masked by hemi-acetal or hemi-ketal formation, are decarbonylated by heating the feed carbohydrate together with a transition metal complex in a suitable solvent. Also, primary alcohols, including sugar alditols are simultaneously dehydrogenated and decarbonylated by heating a mixture of rhodium and ruthenium complexes and the alcohol and optionally a hydrogen acceptor in an acceptable solvent. Such defarbonylation and/or dehydrogenation of sugars provides a convenient procedure for the synthesis of certain carbohydrates and may provide a means for the conversion of biomass into useful products.

  5. Deficiencies

    Data.gov (United States)

    U.S. Department of Health & Human Services — A list of all deficiencies currently listed on Nursing Home Compare, including the nursing home that received the deficiency, the associated inspection date,...

  6. Supported organoiridium catalysts for alkane dehydrogenation

    Science.gov (United States)

    Baker, R. Thomas; Sattelberger, Alfred P.; Li, Hongbo

    2013-09-03

    Solid supported organoiridium catalysts, a process for preparing such solid supported organoiridium catalysts, and the use of such solid supported organoiridium catalysts in dehydrogenation reactions of alkanes is provided. The catalysts can be easily recovered and recycled.

  7. High fat fed heart failure animals have enhanced mitochondrial function and acyl-coa dehydrogenase activities

    Science.gov (United States)

    We have previously shown that administration of high fat in heart failure (HF) increased mitochondrial respiration and did not alter left ventricular (LV) function. PPARalpha is a nuclear transcription factor that activates expression of genes involved in fatty acid uptake and utilization. We hypoth...

  8. On the biologic origin of C6-C10-dicarboxylic and C6-C10-omega-1-hydroxy monocarboxylic acids in human and rat with acyl-CoA dehydrogenation deficiencies: in vitro studies on the omega- and omega-1-oxidation of medium-chain (C6-C12) fatty acids in human and rat liver.

    Science.gov (United States)

    Gregersen, N; Mortensen, P B; Kølvraa, S

    1983-10-01

    C6-C10-dicarboxylic acid C6-C10-omega-1-hydroxy monocarboxylic acids were measured in postmitochondrial (10,000 g) fractions of rat liver after incubation with hexanoic, octanoic, and decanoic acids. In livers both from fed and starved rats, the proportion of decanoic acid converted to sebacic acid was high (approximately 25%) with only minor accumulation of the intermediate 10-hydroxy decanoic acid (1-2%). The conversion of octanoic and hexanoic acids to suberic and adipic acids, respectively, was low (less than 1%). The intermediate 8-hydroxy octanoic and 6-hydroxy hexanoic acids were also accumulated in very small amounts (less than 1%). It was concluded that cytochrome-P-450-mediated omega-hydroxylation was of decisive importance for the production rate of the dicarboxylic acids. Analysis of kinetic parameters of human and rat liver microsomal omega- and omega-1-hydroxylation of hexanoic, octanoic, decanoic, and dodecanoic acids gave the following results: in rats, the apparent Km values for the omega-hydroxylation for dodecanoic and decanoic acids are low, ie., 171 and 3.1 mumole/liter, respectively, whereas they are high for octanoic and hexanoic acids (8211 and 8822 mumole/liter, respectively). In two different humans, the corresponding Km values for dodecanoic, decanoic, octanoic, and hexanoic acids are 3.6-186, 522-247, 4861-3892, and 6825-10400 mumole/liter, respectively. Based on these results, it is argued that adipic and suberic acids found in urine from rats and humans with acyl-CoA dehydrogenation deficiencies are not biosynthesized by direct omega-oxidation of hexanoic and octanoic acids, but most probably by means of beta-oxidation of sebacic and dodecanedioic acids, produced by direct omega-oxidation.(ABSTRACT TRUNCATED AT 250 WORDS)

  9. Catalytic Conversion of Methanol by Oxidative Dehydrogenation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This study investigates the effects of addition of oxygen on the oxidative dehydrogenation (ODH) of methanol when a fluorotetrasilicic mica ion-exchanged with palladium (Pd2+-TSM) was used as the catalyst. The reaction proceeded at a very low temperature in the presence of oxygen, and HCOOCH3 was obtained at high selectivity. By calculating the equilibrium conversion, it has been shown that substantial ODH took place for HCOOCH3 production. Consequently, this reaction would make dehydrogenation the dominant reaction at equilibrium. Not all the H dissociated from CH3OH was converted to H2O by oxidation. It has been shown that the H2O was not produced from oxidative dehydrogenation by the direct reaction of CH3OH and O2 when an attempt was made to carry out oxidative dehydrogenation using an isotope oxygen trace method in the gas phase. Therefore, when CH3OH was converted to CO2 and dehydrogenated to HCOOCH3, the C-O bonds were not dissociated.

  10. Dehydrogenation of liquid fuel in microchannel catalytic reactor

    Science.gov (United States)

    Toseland, Bernard Allen; Pez, Guido Peter; Puri, Pushpinder Singh

    2009-02-03

    The present invention is an improved process for the storage and delivery of hydrogen by the reversible hydrogenation/dehydrogenation of an organic compound wherein the organic compound is initially in its hydrogenated state. The improvement in the route to generating hydrogen is in the dehydrogenation step and recovery of the dehydrogenated organic compound resides in the following steps: introducing a hydrogenated organic compound to a microchannel reactor incorporating a dehydrogenation catalyst; effecting dehydrogenation of said hydrogenated organic compound under conditions whereby said hydrogenated organic compound is present as a liquid phase; generating a reaction product comprised of a liquid phase dehydrogenated organic compound and gaseous hydrogen; separating the liquid phase dehydrogenated organic compound from gaseous hydrogen; and, recovering the hydrogen and liquid phase dehydrogenated organic compound.

  11. Dehydrogenated polycyclic aromatic hydrocarbons and UV bump

    CERN Document Server

    Malloci, G; Cecchi-Pestellini, C; Joblin, C

    2008-01-01

    Recent calculations have shown that the UV bump at about 217.5 nm in the extinction curve can be explained by a complex mixture of PAHs in several charge states. Other studies proposed that the carriers are a restricted population made of neutral and singly-ionised dehydrogenated coronene molecules (C24Hn, n less than 3), in line with models of the hydrogenation state of interstellar PAHs predicting that medium-sized species are highly dehydrogenated. To assess the observational consequences of the latter hypothesis we have undertaken a systematic study of the electronic spectra of dehydrogenated PAHs. We use our first results to see whether such spectra show strong general trends upon dehydrogenation. We used state-of-the-art techniques in the framework of the density functional theory (DFT) to obtain the electronic ground-state geometries, and of the time- dependent DFT to evaluate the electronic excited-state properties. We computed the absorption cross-section of the species C24Hn (n=12,10,8,6,4,2,0) in t...

  12. Development of Non-Noble Metal Ni-Based Catalysts for Dehydrogenation of Methylcyclohexane

    KAUST Repository

    Al-ShaikhAli, Anaam H.

    2016-11-30

    of strongly chemisorbed intermediate originating from TOL. DFT calculation indicated that Zn metal prefers to occupy the step sites of Ni where unselective C–C bond breaking was considered to preferentially occur, explaining suppression of hydrogenolysis activity. Additionally, it confirmed that the H-deficient species at methyl position group (C6H5CH2) was stable on the surface, making its hydrogenation being rate determining step, consistent with positive order in H2 pressure on TOL formation rate. This may explain the conclusive role by H2 in facilitating desorption of the H-deficient surface species that was produced through further dehydrogenation of TOL.

  13. Thermodynamic aspects of dehydrogenation reactions on noble metal surfaces.

    Science.gov (United States)

    Svane, K L; Hammer, B

    2014-11-01

    The reaction free energy for dehydrogenation of phenol, aniline, thiophenol, benzoic acid, and 1,4-benzenediol on the close packed copper, silver, and gold surfaces has been studied by density functional theory calculations. Dehydrogenation of thiophenol is found to be favourable on all three surfaces while aniline does not dehydrogenate on any of them. For phenol, benzenediol and benzoic acid dehydrogenation is favourable on copper and silver only, following the general trend of an increasing reaction free energy when going form gold to silver to copper. This trend can be correlated with the changes in bond lengths within the molecule upon dehydrogenation. While copper is able to replace hydrogen, leaving small changes in the bond lengths of the aromatic ring, the metal-molecule bond is weaker for silver and gold, resulting in a partial loss of aromaticity. This difference in bond strength leads to pronounced differences in adsorption geometries upon multiple dehydrogenations.

  14. Microchannel apparatus and methods of conducting catalyzed oxidative dehydrogenation

    Science.gov (United States)

    Tonkovich, Anna Lee; Yang, Bin; Perry, Steven T.; Mazanec, Terry; Arora, Ravi; Daly, Francis P.; Long, Richard; Yuschak, Thomas D.; Neagle, Paul W.; Glass, Amanda

    2011-08-16

    Methods of oxidative dehydrogenation are described. Surprisingly, Pd and Au alloys of Pt have been discovered to be superior for oxidative dehydrogenation in microchannels. Methods of forming these catalysts via an electroless plating methodology are also described. An apparatus design that minimizes heat transfer to the apparatus' exterior is also described.

  15. Current-induced runaway vibrations in dehydrogenated graphene nanoribbons

    DEFF Research Database (Denmark)

    Christensen, Rasmus Bjerregaard; Lu, Jing Tao; Hedegard, Per

    2016-01-01

    We employ a semi-classical Langevin approach to study current-induced atomic dynamics in a partially dehydrogenated armchair graphene nanoribbon. All parameters are obtained from density functional theory. The dehydrogenated carbon dimers behave as effective impurities, whose motion decouples from...

  16. Transition metal catalysed ammonia-borane dehydrogenation in ionic liquids.

    Science.gov (United States)

    Wright, William R H; Berkeley, Emily R; Alden, L R; Baker, R Tom; Sneddon, Larry G

    2011-03-21

    Significant advantages result from combining the disparate hydrogen release pathways for ammonia-borane (AB) dehydrogenation using ionic liquids (ILs) and transition metal catalysts. With the RuCl(2)(PMe(3))(4) catalyst precursor, AB dehydrogenation selectivity and extent are maximized in an IL with a moderately coordinating ethylsulfate anion.

  17. Iridium-catalyzed intermolecular dehydrogenative silylation of polycyclic aromatic compounds without directing groups.

    Science.gov (United States)

    Murai, Masahito; Takami, Keishi; Takai, Kazuhiko

    2015-03-16

    This study describes the iridium-catalyzed intermolecular dehydrogenative silylation of C(sp(2))-H bonds of polycyclic aromatic compounds without directing groups. The reaction produced various arylsilanes through both Si-H and C-H bond activation, with hydrogen as the sole byproduct. Reactivity was affected by the electronic nature of the aromatic compounds, and silylation of electron-deficient and polycyclic aromatic compounds proceeded efficiently. Site-selectivity was controlled predominantly by steric factors. Therefore, the current functionalization proceeded with opposite chemo- and site-selectivity compared to that observed for general electrophilic functionalization of aromatic compounds.

  18. Production of pure hydrogen by ethanol dehydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Santacesaria, E.; Carotenuto, G.; Tesser, R.; Di Serio, M. [Naples ' ' Federico II' ' Univ. (Italy). Dept. of Chemistry

    2010-12-30

    Hydrogen production from bio-ethanol is one of the most promising renewable processes to generate electricity using fuel cells. In this work, we have studied the production of pure hydrogen as by product of ethanol dehydrogenation reaction. This reaction is promoted by copper based catalysts and according to the catalyst used and the operative conditions gives place to acetaldehyde or ethyl acetate as main products. We studied in particular the performance of a commercial copper/copper chromite catalyst, supported on alumina and containing barium chromate as promoter that has given the best results. By operating at low pressure and temperature with short residence times, acetaldehyde is more selectively produced, while, by increasing the pressure (10-30 bars), the temperature (200-260 C) and the residence time (about 100 (grams hour/mol) of ethanol contact time) the selectivity is shifted to the production of ethyl acetate. However, in both cases pure hydrogen is obtained, as by product, that can easily be separated. Hydrogen obtained in this way is exempt of CO and can be directly fed to fuel cells without any inconvenience. In this work, runs performed in different operative conditions have been reported with the scope to individuate the best conditions. A carrier of H{sub 2} 6% in N{sub 2} has been used. The studied catalyst has also shown a good thermal stability with respect to sintering phenomena, that generally occurs during the dehydrogenation on other copper catalysts. Hydrogen productivities of 8-39 mol{sub H2} (gcat){sup -1}(h){sup -1} have been obtained for the explored temperature range 200-260 C. At last, the most accredited reaction mechanism is reported and discussed on the basis of the obtained results. (orig.)

  19. Adsorption and dehydrogenation of tetrahydroxybenzene on Cu(111)

    DEFF Research Database (Denmark)

    Bebensee, Fabian; Svane, K.; Bombis, Christian

    2013-01-01

    Adsorption of tetrahydroxybenzene (THB) on Cu(111) and Au(111) surfaces is studied using a combination of STM, XPS, and DFT. THB is deposited intact, but on Cu(111) it undergoes gradual dehydrogenation of the hydroxyl groups as a function of substrate temperature, yielding a pure dihydroxy......-benzoquinone phase at 370 K. Subtle changes to the adsorption structure upon dehydrogenation are explained from differences in molecule–surface bonding....

  20. Disruption of the acyl-coa binding protein gene delays hepatic adaptation to metabolic changes at weaning

    DEFF Research Database (Denmark)

    Neess, Ditte; Bloksgaard, Maria; Sørensen, Signe Bek;

    2011-01-01

    , little is known about the in vivo function in mammalian cells. We have generated mice with targeted disruption of ACBP (ACBP-/-). These mice are viable and fertile and develop normally. However, around weaning the ACBP-/- mice go through a crisis with overall weakness, and a slightly decreased growth...... rate. Using microarray analysis we show that the liver of ACBP-/- mice display a significantly delayed adaptation to weaning with late induction of target genes of the sterol regulatory element binding protein (SREBP) family. As a result, hepatic de novo cholesterogenesis is decreased at weaning....... The delayed induction of SREBP target genes around weaning is caused by a compromised processing and decreased expression of SREBP precursors leading to reduced binding of SREBP to target sites in chromatin. In conclusion, lack of ACBP interferes with the normal metabolic adaptation to weaning and leads...

  1. Dehydrogenation of polycyclic aromatic hydrocarbons in the diffuse interstellar medium

    CERN Document Server

    Foing, B H

    2000-01-01

    We present a model for the hydrogenation states of Polycyclic Aromatic Hydrocarbons (PAHs) in the diffuse interstellar medium. First, we study the abundance of hydrogenation and charge states of PAHs due to photo-ionization, photo-dissociation in the interstellar UV field, electron recombination and chemical reactions between PAH cations and H or H_2. For PAH cations, we find that the dehydrogenation effects are dominant. The hydrogenation state of PAHs depends strongly on the H density, the size of the molecule and UV field. In diffuse clouds with low H density and normal UV radiation, PAHs containing less than 40 C are completely or strongly dehydrogenated whereas at high H density, they are normally hydrogenated. The partially dehydrogenated species dominate in intermediate density clouds. PAHs above 40 C are quite stable and are fully hydrogenated, which would favor their spectroscopic search in near IR surveys of Diffuse Interstellar Bands (DIBs).

  2. Embedded silicene nanostructures in partly-dehydrogenated polysilane.

    Science.gov (United States)

    Li, Xiuling; Zeng, Xiao Cheng; Wu, Xiaojun

    2017-04-05

    Developing freestanding silicene nanostructures with tunable electronic and magnetic properties is of particular importance for their applications in nanoelectronics, but still faces big challenges. On the basis of first-principles calculations, here we predict that embedded silicene nanoflakes and nanoribbons can be realized by partly dehydrogenating a freestanding polysilane (Si6H6) sheet. Born-Oppenheimer molecular dynamics simulations indicate that the embedded silicene nanostructures show good thermal stability at 500 K. In particular, the embedded silicene nanostructures exhibit similar electronics properties to those of isolated ones. These findings imply a practical solution to produce embedded silicene nanostructures from partly dehydrogenated freestanding polysilane.

  3. Ruthenium-Catalyzed Ammonia Borane Dehydrogenation: Mechanism and Utility.

    Science.gov (United States)

    Zhang, Xingyue; Kam, Lisa; Trerise, Ryan; Williams, Travis J

    2017-01-17

    One of the greatest challenges in using H2 as a fuel source is finding a safe, efficient, and inexpensive method for its storage. Ammonia borane (AB) is a solid hydrogen storage material that has garnered attention for its high hydrogen weight density (19.6 wt %) and ease of handling and transport. Hydrogen release from ammonia borane is mediated by either hydrolysis, thus giving borate products that are difficult to rereduce, or direct dehydrogenation. Catalytic AB dehydrogenation has thus been a popular topic in recent years, motivated both by applications in hydrogen storage and main group synthetic chemistry. This Account is a complete description of work from our laboratory in ruthenium-catalyzed ammonia borane dehydrogenation over the last 6 years, beginning with the Shvo catalyst and resulting ultimately in the development of optimized, leading catalysts for efficient hydrogen release. We have studied AB dehydrogenation with Shvo's catalyst extensively and generated a detailed understanding of the role that borazine, a dehydrogenation product, plays in the reaction: it is a poison for both Shvo's catalyst and PEM fuel cells. Through independent syntheses of Shvo derivatives, we found a protective mechanism wherein catalyst deactivation by borazine is prevented by coordination of a ligand that might otherwise be a catalytic poison. These studies showed how a bidentate N-N ligand can transform the Shvo into a more reactive species for AB dehydrogenation that minimizes accumulation of borazine. Simultaneously, we designed novel ruthenium catalysts that contain a Lewis acidic boron to replace the Shvo -OH proton, thus offering more flexibility to optimize hydrogen release and take on more general problems in hydride abstraction. Our scorpionate-ligated ruthenium species (12) is a best-of-class catalyst for homogeneous dehydrogenation of ammonia borane in terms of its extent of hydrogen release (4.6 wt %), air tolerance, and reusability. Moreover, a synthetically

  4. Characterizing the infrared spectra of small, neutral, fully dehydrogenated PAHs

    CERN Document Server

    Mackie, C J; Bauschlicher, C W; Cami, J

    2014-01-01

    We present the results of a computational study to investigate the infrared spectroscopic properties of a large number of polycyclic aromatic hydrocarbon (PAH) molecules and their fully dehydrogenated counterparts. We constructed a database of fully optimized geometries for PAHs that is complete for eight or fewer fused benzene rings, thus containing 1550 PAHs and 805 fully dehydrogenated aromatics. A large fraction of the species in our database have clearly non-planar or curved geometries. For each species, we determined the frequencies and intensities of their normal modes using density functional theory calculations. Whereas most PAH spectra are fairly similar, the spectra of fully dehydrogenated aromatics are much more diverse. Nevertheless, these fully dehydrogenated species show characteristic emission features at 5.2$\\mu$m, 5.5$\\mu$m and 10.6$\\mu$m; at longer wavelengths, there is a forest of emission features in the 16--30$\\mu$m range that appears as a structured continuum, but with a clear peak cent...

  5. Dehydrogenation of goethite in Earth’s deep lower mantle

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Qingyang; Kim, Duck Young; Liu, Jin; Meng, Yue; Yang, Liuxiang; Zhang, Dongzhou; Mao, Wendy L.; Mao, Ho-kwang

    2017-01-31

    The cycling of hydrogen influences the structure, composition, and stratification of Earth’s interior. Our recent discovery of pyrite-structured iron peroxide (designated as the P phase) and the formation of the P phase from dehydrogenation of goethite FeO2H implies the separation of the oxygen and hydrogen cycles in the deep lower mantle beneath 1,800 km. Here we further characterize the residual hydrogen, x, in the P-phase FeO2Hx. Using a combination of theoretical simulations and high-pressure–temperature experiments, we calibrated the x dependence of molar volume of the P phase. Within the current range of experimental conditions, we observed a compositional range of P phase of 0.39 < x < 0.81, corresponding to 19–61% dehydrogenation. Increasing temperature and heating time will help release hydrogen and lower x, suggesting that dehydrogenation could be approaching completion at the high-temperature conditions of the lower mantle over extended geological time. Our observations indicate a fundamental change in the mode of hydrogen release from dehydration in the upper mantle to dehydrogenation in the deep lower mantle, thus differentiating the deep hydrogen and hydrous cycles.

  6. Transfer Methane to Fragrant Hydrocarbon by Direct Catalyzed Dehydrogenation

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ Sponsored by NSFC,a research project -"Transfer methane to fragrant hydrocarbon by direct catalyzed dehydrogenation",directed by Prof.Xin Bao from Dalian Institute of Chemical Physics of CAS,honored the 2nd class National Science & Technology Award in 2005.

  7. Propane Dehydrogenation on Metal and Metal Oxide Catalysts

    NARCIS (Netherlands)

    Sattler, Jesper

    2014-01-01

    In this PhD thesis, the catalytic performance and deactivation of various propane dehydrogenation catalysts is studied. First of all, a literature study is performed, where the three most commonly used formulations, namely Pt-, CrOx- and GaOx-based catalysts are compared in terms of yield relative t

  8. Kinetic modeling of ethylbenzene dehydrogenation over hydrotalcite catalysts

    KAUST Repository

    Atanda, Luqman

    2011-07-01

    Kinetics of ethylbenzene dehydrogenation to styrene was investigated over a series of quaternary mixed oxides of Mg3Fe0.25Me0.25Al0.5 (Me=Co, Mn and Ni) catalysts prepared by calcination of hydrotalcite-like compounds and compared with commercial catalyst. The study was carried out in the absence of steam using a riser simulator at 400, 450, 500 and 550°C for reaction times of 5, 10, 15 and 20s. Mg3Fe0.25Mn0.25Al0.5 afforded the highest ethylbenzene conversion of 19.7% at 550°C. Kinetic parameters for the dehydrogenation process were determined using the catalyst deactivation function based on reactant conversion model. The apparent activation energies for styrene production were found to decrease as follows: E1-Ni>E1-Co>E1-Mn. © 2011 Elsevier B.V.

  9. Current-induced runaway vibrations in dehydrogenated graphene nanoribbons

    DEFF Research Database (Denmark)

    Christensen, Rasmus Bjerregaard; Lu, Jing Tao; Hedegard, Per;

    2016-01-01

    We employ a semi-classical Langevin approach to study current-induced atomic dynamics in a partially dehydrogenated armchair graphene nanoribbon. All parameters are obtained from density functional theory. The dehydrogenated carbon dimers behave as effective impurities, whose motion decouples from...... the rest of carbon atoms. The electrical current can couple the dimer motion in a coherent fashion. The coupling, which is mediated by nonconservative and pseudo-magnetic current-induced forces, change the atomic dynamics, and thereby show their signature in this simple system. We study the atomic dynamics...... and current-induced vibrational instabilities using a simplified eigen-mode analysis. Our study illustrates how armchair nanoribbons can serve as a possible testbed for probing the current-induced forces....

  10. Carbon mediated catalysis:A review on oxidative dehydrogenation

    Institute of Scientific and Technical Information of China (English)

    De Chen; Anders Holmen; Zhijun Sui; Xinggui Zhou

    2014-01-01

    Carbon mediated catalysis has gained an increasing attention in both areas of nanocatalysis and nanomaterials. The progress in carbon nanomaterials provides many new opportunities to manip-ulate the types and properties of active sites of catalysts through manipulating structures, function-alities and properties of carbon surfaces. The present review focuses on progresses in carbon medi-ated oxidative dehydrogenation reactions of ethylbenzene, propane, and butane. The state-of-the-art of the developments of carbon mediated catalysis is discussed in terms of fundamental studies on adsorption of oxygen and hydrocarbons, reaction mechanism as well as effects of carbon nano-material structures and surface functional groups on the catalytic performance. We highlight the importance and challenges in tuning of the electron density of carbon and oxygen on carbon surfac-es for improving selectivity in oxidative dehydrogenation reactions.

  11. Current-induced runaway vibrations in dehydrogenated graphene nanoribbons

    Directory of Open Access Journals (Sweden)

    Rasmus Bjerregaard Christensen

    2016-01-01

    Full Text Available We employ a semi-classical Langevin approach to study current-induced atomic dynamics in a partially dehydrogenated armchair graphene nanoribbon. All parameters are obtained from density functional theory. The dehydrogenated carbon dimers behave as effective impurities, whose motion decouples from the rest of carbon atoms. The electrical current can couple the dimer motion in a coherent fashion. The coupling, which is mediated by nonconservative and pseudo-magnetic current-induced forces, change the atomic dynamics, and thereby show their signature in this simple system. We study the atomic dynamics and current-induced vibrational instabilities using a simplified eigen-mode analysis. Our study illustrates how armchair nanoribbons can serve as a possible testbed for probing the current-induced forces.

  12. Dehydrogenation of Light Alkanes over Supported Pt Catalysts

    OpenAIRE

    Wu, Jason

    2015-01-01

    The production of light alkenes comprises a 250 million ton per year industry due to their extensive use in the production of plastics, rubbers, fuel blending agents, and chemical intermediates. While steam cracking and fluid catalytic cracking of petroleum crude oils are the most common methods for obtaining light alkenes, rising oil prices and low selectivities toward specific alkenes have driven the search for a more economical and efficient process. Catalytic dehydrogenation of light alka...

  13. Effect of alloying on carbon formation during ethane dehydrogenation

    DEFF Research Database (Denmark)

    Rovik, Anne; Kegnæs, Søren; Dahl, Søren

    2009-01-01

    The structure sensitivity of different transition metals in the hydrogenolysis, dehydrogenation, and coking reactions during ethane conversion has been investigated. The investigated metals, Ni, Ru, Rh, and Pd, are co-impregnated with Ag onto an inactive MgAl2O4 spinel support and tested in the c......The structure sensitivity of different transition metals in the hydrogenolysis, dehydrogenation, and coking reactions during ethane conversion has been investigated. The investigated metals, Ni, Ru, Rh, and Pd, are co-impregnated with Ag onto an inactive MgAl2O4 spinel support and tested...... in the conversion of ethane. A tendency is clear for all catalysts: In the first period of time 100% ethane is converted and roughly half of the carbon is converted into coke and deposited on the catalyst. The other half of the carbon is converted into methane. The active sites in the hydrogenolysis are blocked...... by coke during the initial period where after dehydrogenation of ethane is observed. It has previously been predicted in surface science studies that Ag covers the steps of certain transition metals. Here it is documented that the hydrogenolysis and coking reactions are significantly suppressed by co...

  14. Dehydrogenation kinetics and reversibility of LiAlH4-LiBH4 doped with Ti-based additives and MWCNT

    Science.gov (United States)

    Thaweelap, Natthaporn; Utke, Rapee

    2016-11-01

    Dehydrogenation kinetics and reversibility of LiAlH4-LiBH4 doped with Ti-based additives (TiCl3 and Ti-isopropoxide), multiwall carbon nanotubes (MWCNT), and MWCNT impregnated with Ti-based additives are proposed. Reduction of dehydrogenation temperature as well as improvements of kinetics and reversibility, especially decomposition of thermodynamically stable hydride (LiBH4) is obtained from the samples doped with Ti-isopropoxide and MWCNT. This can be due to the fact that the formations of LixAl(1-x)B2 and LiH-Al containing phase during dehydrogenation favor decomposition of LiH, leading to increment of hydrogen capacity, and stabilization of boron in solid state, resulting in improvement of reversibility. Besides, the curvatures and thermal conductivity of MWCNT benefit hydrogen diffusion and heat transfer during de/rehydrogenation. Nevertheless, deficient hydrogen content reversible is observed in all samples due to the irreversible of LiAlH4 and/or Li3AlH6 as well as the formation of stable phase (Li2B12H12) during de/rehydrogenation.

  15. Effect of hydrogen combustion reaction on the dehydrogenation of ethane in a fixed-bed catalytic membrane reactor

    Institute of Scientific and Technical Information of China (English)

    Masoud Hasany; Mohammad Malakootikhah; Vahid Rahmanian; Soheila Yaghmaei

    2015-01-01

    A two-dimensional non-isothermal mathematical model has been developed for the ethane dehydrogenation reaction in a fixed-bed catalytic membrane reactor. Since ethane dehydrogenation is an equilibrium reaction, removal of produced hydrogen by the membrane shifts the thermodynamic equilibrium to ethylene production. For further displacement of the dehydrogenation reaction, oxidative dehydrogenation method has been used. Since ethane dehydrogenation is an endothermic reaction, the energy produced by the oxidative dehydrogena-tion method is consumed by the dehydrogenation reaction. The results show that the oxidative dehydrogenation method generated a substantial improvement in the reactor performance in terms of high conversions and significant energy saving. It was also established that the sweep gas velocity in the shell side of the reactor is one of the most important factors in the effectiveness of the reactor.

  16. Structures of the dehydrogenation products of methane activation by 5d transition metal cations

    NARCIS (Netherlands)

    Lapoutre, V. J. F.; Redlich, B.; van der Meer, A. F. G.; Oomens, J.; Bakker, J. M.; Sweeney, A.; Mookherjee, A.; Armentrout, P. B.

    2013-01-01

    The activation of methane by gas-phase transition metal cations (M +) has been studied extensively, both experimentally and using density functional theory (DFT). Methane is exothermically dehydrogenated by several 5d metal ions to form [M,C,2H]+ and H2. However, the structure of the dehydrogenation

  17. Photocatalytic acceptorless alkane dehydrogenation: scope, mechanism, and conquering deactivation with carbon dioxide.

    Science.gov (United States)

    Chowdhury, Abhishek Dutta; Julis, Jennifer; Grabow, Kathleen; Hannebauer, Bernd; Bentrup, Ursula; Adam, Martin; Franke, Robert; Jackstell, Ralf; Beller, Matthias

    2015-01-01

    Alkane dehydrogenation is of special interest for basic science but also offers interesting opportunities for industry. The existing dehydrogenation methodologies make use of heterogeneous catalysts, which suffer from harsh reaction conditions and a lack of selectivity, whereas homogeneous methodologies rely mostly on unsolicited waste generation from hydrogen acceptors. Conversely, acceptorless photochemical alkane dehydrogenation in the presence of trans-Rh(PMe3 )2 (CO)Cl can be regarded as a more benign and atom efficient alternative. However, this methodology suffers from catalyst deactivation over time. Herein, we provide a detailed investigation of the trans-Rh(PMe3 )2 (CO)Cl-photocatalyzed alkane dehydrogenation using spectroscopic and theoretical investigations. These studies inspired us to utilize CO2 to prevent catalyst deactivation, which leads eventually to improved catalyst turnover numbers in the dehydrogenation of alkanes that include liquid organic hydrogen carriers.

  18. Propane Dehydrogenation over a Commercial Pt-Sn/Al2O3 Catalyst for Isobutane Dehydrogenation: Optimization of Reaction Conditions

    Institute of Scientific and Technical Information of China (English)

    Farnaz Tahriri Zangeneh; Saeed Sahebdelfar; Mohsen Bahmani

    2013-01-01

    The applicability of a commercial Pt-Sn/Al2O3 isobutane dehydrogenation catalyst in dehydrogenation of propane was studied.Catalyst performance tests were carried out in a fixed-bed quartz reactor under different operating conditions.Generally,as the factors improving propane conversion decrease the propylene selectivity,the optimal operating condition to maximize propylene yield is expected.The optimal condition was obtained by the experimental design method.The investigated parameters were temperature,hydrogen/hydrocarbon (H2/HC) ratio and space velocity,being changed in three levels.Constrains such as the susceptibility of the catalyst components to sintering or phase transformation were also taken into account.Activity,selectivity and stability of the catalyst were considered as the measured response factors,while the space-time-yield (STY) was considered as the variable to be optimized due to its commercial interest.A STY of 16 mol·kg-1·h-1 was achieved under the optimal conditions of T=620 ℃,H2/HC =0.6 and,weight hourly space velocity (WHSV) =2.2 h-1.Single carbon-carbon bond rupture was found to be the main route for the formation of lower hydrocarbon byproducts.

  19. Synthesis of Borohydride and Catalytic Dehydrogenation by Hydrogel Based Catalyst

    Science.gov (United States)

    Boynuegri, Tugba Akkas; Karabulut, Ahmet F.; Guru, Metin

    2016-08-01

    This paper deals with the synthesis of calcium borohydride (Ca(BH4)2) as hydrogen storage material. Calcium chloride salt (CaCl2), magnesium hydride (MgH2), and boron oxide (B2O3) were used as reactants in the mechanochemical synthesis of Ca(BH4)2. The mechanochemical reaction was carried out by means of Spex type ball milling without applying high pressure and temperature. Parametric studies have been established at different reaction times and for different amounts of reactants at a constant ball to powder ratio (BPR) 4:1. The best combination was determined by Fourier Transform Infrared (FT-IR) analysis. According to the FT-IR analysis, reaction time, the first reaction parameter, was found as 1600 min. After the reaction time was fixed at 1600 min, the difference of the B-H peak areas was dependent on the amount of reactant MgH2 that was investigated. The amount of the reactant (MgH2), the second reaction parameter, was measured to be 2.85 times more than the stoichiometric amount of MgH2. According to our previous studies, BPR was selected as 4:1 for all experiments. Samples were prepared in a glove box under argon atmosphere but the time that elapsed for FT-IR analysis highly affected B-H bonds. B-H peak areas clearly decreased with time because of negative effect of ambient atmosphere. A catalyst was prepared by absorbing cobalt fluoride (CoF2) in poly (acrylamide-co-acrylic acid) hydrogel matrices type and its catalytic dehydrogenation performance that has been characterized by the catalytic reaction of sodium borohydride's known hydrogen capacity in an alkaline medium. The metal amount of hydrogel catalyst was determined as 135.82 mg Co by Atomic Absorption Spectroscopy (AAS). The specific dehydrogenation capacity of the Co active compound in the catalyst thanks to catalytic dehydrogenation of commercial sodium borohydride was measured as 1.66 mL H2/mg Co.

  20. PNP pincer osmium polyhydrides for catalytic dehydrogenation of primary alcohols.

    Science.gov (United States)

    Bertoli, Marcello; Choualeb, Aldjia; Gusev, Dmitry G; Lough, Alan J; Major, Quinn; Moore, Brandon

    2011-09-21

    This paper reports the synthesis, structure, and properties of a series of PNP pincer complexes of osmium OsH(3)Cl[HN(C(2)H(4)P(i)Pr(2))(2)] (1), OsH(3)[N(C(2)H(4)P(i)Pr(2))(2)] (2), OsH(4)[HN(C(2)H(4)P(i)Pr(2))(2)] (3), and OsH(2)(PMe(3))[HN(C(2)H(4)P(i)Pr(2))(2)] (4). The tetrahydride 3 operates as an efficient catalyst at 0.1 mol% loading for the reactions of amination and dehydrogenative coupling of primary alcohols, producing secondary amines and symmetrical esters, respectively. The catalyst 3 is distinguished by outstanding stability, and it can be used in an aqueous environment at temperatures as high as 200 °C.

  1. Kinetics with deactivation of methylcyclohexane dehydrogenation for hydrogen energy storage

    Energy Technology Data Exchange (ETDEWEB)

    Maria, G.; Marin, A.; Wyss, C.; Mueller, S.; Newson, E. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    The methylcyclohexane dehydrogenation step to recycle toluene and release hydrogen is being studied as part of a hydrogen energy storage project. The reaction is performed catalytically in a fixed bed reactor, and the efficiency of this step significantly determines overall system economics. The fresh catalyst kinetics and the deactivation of the catalyst by coke play an important role in the process analysis. The main reaction kinetics were determined from isothermal experiments using a parameter sensitivity analysis for model discrimination. An activation energy for the main reaction of 220{+-}11 kJ/mol was obtained from a two-parameter model. From non-isothermal deactivation in PC-controlled integral reactors, an activation energy for deactivation of 160 kJ/mol was estimated. A model for catalyst coke content of 3-17 weight% was compared with experimental data. (author) 3 figs., 6 refs.

  2. Spectroscopic evidence for origins of size and support effects on selectivity of Cu nanoparticle dehydrogenation catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Witzke, M. E.; Dietrich, P. J.; Ibrahim, M. Y. S.; Al-Bardan, K.; Triezenberg, M. D.; Flaherty, D. W.

    2016-12-12

    Selective dehydrogenation catalysts that produce acetaldehyde from bio-derived ethanol can increase the efficiency of subsequent processes such as C–C coupling over metal oxides to produce 1-butanol or 1,3-butadiene or oxidation to acetic acid. Here, we use in situ X-ray absorption spectroscopy and steady state kinetics experiments to identify Cuδ+ at the perimeter of supported Cu clusters as the active site for esterification and Cu0 surface sites as sites for dehydrogenation. Correlation of dehydrogenation and esterification selectivities to in situ measures of Cu oxidation states show that this relationship holds for Cu clusters over a wide-range of diameters (2–35 nm) and catalyst supports and reveals that dehydrogenation selectivities may be controlled by manipulating either.

  3. Regioselective acceptorless dehydrogenative coupling of N-heterocycles toward functionalized quinolines, phenanthrolines, and indoles.

    Science.gov (United States)

    Talwar, Dinesh; Gonzalez-de-Castro, Angela; Li, Ho Yin; Xiao, Jianliang

    2015-04-20

    A new strategy has been developed for the oxidant- and base-free dehydrogenative coupling of N-heterocycles at mild conditions. Under the action of an iridium catalyst, N-heterocycles undergo multiple sp(3) CH activation steps, generating a nucleophilic enamine that reacts in situ with various electrophiles to give highly functionalized products. The dehydrogenative coupling can be cascaded with Friedel-Crafts addition, resulting in a double functionalization of the N-heterocycles.

  4. Water co-catalyzed selective dehydrogenation of methanol to formaldehyde and hydrogen

    Science.gov (United States)

    Shan, Junjun; Lucci, Felicia R.; Liu, Jilei; El-Soda, Mostafa; Marcinkowski, Matthew D.; Allard, Lawrence F.; Sykes, E. Charles H.; Flytzani-Stephanopoulos, Maria

    2016-08-01

    The non-oxidative dehydrogenation of methanol to formaldehyde is considered a promising method to produce formaldehyde and clean hydrogen gas. Although Cu-based catalysts have an excellent catalytic activity in the oxidative dehydrogenation of methanol, metallic Cu is commonly believed to be unreactive for the dehydrogenation of methanol in the absence of oxygen adatoms or oxidized copper. Herein we show that metallic Cu can catalyze the dehydrogenation of methanol in the absence of oxygen adatoms by using water as a co-catalyst both under realistic reaction conditions using silica-supported PtCu nanoparticles in a flow reactor system at temperatures below 250 °C, and in ultra-high vacuum using model PtCu(111) catalysts. Adding small amounts of isolated Pt atoms into the Cu surface to form PtCu single atom alloys (SAAs) greatly enhances the dehydrogenation activity of Cu. Under the same reaction conditions, the yields of formaldehyde from PtCu SAA nanoparticles are more than one order of magnitude higher than on the Cu nanoparticles, indicating a significant promotional effect of individual, isolated Pt atoms. Moreover, this study also shows the unexpected role of water in the activation of methanol. Water, a catalyst for methanol dehydrogenation at low temperatures, becomes a reactant in the methanol steam reforming reactions only at higher temperatures over the same metal catalyst.

  5. A visible light photocatalytic cross-dehydrogenative coupling/dehydrogenation/6π-cyclization/oxidation cascade: synthesis of 12-nitroindoloisoquinolines from 2-aryltetrahydroisoquinolines.

    Science.gov (United States)

    Rusch, Fabian; Unkel, Lisa-Natascha; Alpers, Dirk; Hoffmann, Frank; Brasholz, Malte

    2015-06-01

    A visible light-induced photocatalytic dehydrogenation/6π-cyclization/oxidation cascade converts 1-(nitromethyl)-2-aryl-1,2,3,4-tetrahydroisoquinolines into novel 12-nitro-substituted tetracyclic indolo[2,1-a]isoquinoline derivatives. Various photocatalysts promote the reaction in the presence of air and a base, the most efficient being 1-aminoanthraquinone in combination with K3 PO4 . Further, the 12-nitroindoloisoquinoline products can be accessed directly from C1-unfunctionalized 2-aryl-1,2,3,4-tetrahydroisoquinolines by extending the one-pot protocol with a foregoing photocatalytic cross-dehydrogenative coupling reaction, resulting in a quadruple cascade transformation.

  6. Arabidopsis CER8 encodes LONG-CHAIN ACYL-COA SYNTHETASE 1 (LACS1) that has overlapping functions with LACS2 in plant wax and cutin synthesis.

    Science.gov (United States)

    Lü, Shiyou; Song, Tao; Kosma, Dylan K; Parsons, Eugene P; Rowland, Owen; Jenks, Matthew A

    2009-08-01

    Plant cuticle is an extracellular lipid-based matrix of cutin and waxes, which covers aerial organs and protects them from many forms of environmental stress. We report here the characterization of CER8/LACS1, one of nine Arabidopsis long-chain acyl-CoA synthetases thought to activate acyl chains. Mutations in LACS1 reduced the amount of wax in all chemical classes on the stem and leaf, except in the very long-chain fatty acid (VLCFA) class wherein acids longer than 24 carbons (C(24)) were elevated more than 155%. The C(16) cutin monomers on lacs1 were reduced by 37% and 22%, whereas the C(18) monomers were increased by 28% and 20% on stem and leaf, respectively. Amounts of wax and cutin on a lacs1-1 lacs2-3 double mutant were much lower than on either parent, and lacs1-1 lacs2-3 had much higher cuticular permeability than either parent. These additive effects indicate that LACS1 and LACS2 have overlapping functions in both wax and cutin synthesis. We demonstrated that LACS1 has synthetase activity for VLCFAs C(20)-C(30), with highest activity for C(30) acids. LACS1 thus appears to function as a very long-chain acyl-CoA synthetase in wax metabolism. Since C(16) but not C(18) cutin monomers are reduced in lacs1, and C(16) acids are the next most preferred acid (behind C(30)) by LACS1 in our assays, LACS1 also appears to be important for the incorporation of C(16) monomers into cutin polyester. As such, LACS1 defines a functionally novel acyl-CoA synthetase that preferentially modifies both VLCFAs for wax synthesis and long-chain (C(16)) fatty acids for cutin synthesis.

  7. Process for alkane group dehydrogenation with organometallic catalyst

    Science.gov (United States)

    Kaska, William C.; Jensen, Craig M.

    1998-01-01

    An improved process is described for the catalytic dehydrogenation of organic molecules having a ##STR1## group to produce a ##STR2## group. The organic molecules are: ##STR3## wherein: A.sup.1, A.sup.2, A.sup.3, and A.sup.4 are each independently P, As or N: E.sup.2 is independently C or N; E.sup.3 is independently C, Si or Ge; E.sup.4 is independently C, Si, or Ge; and E.sup.5 is independently C, Si or Ge; M.sup.1, M.sup.2, M.sup.3, and M.sup.4 each is a metal atom independently selected from the group consisting of ruthenium, rhodium, palladium, osmium, iridium and platinum; Q.sup.1, Q.sup.2, Q.sup.3, and Q.sup.4 are each independently a direct bond, --CH.sub.2 --, --CH.sub.2 CH.sub.2 --, or CH.dbd.CH--; in structure I, structure II or structure IV, R.sup.1, R.sup.2, R.sup.3, and R.sup.4 are each independently selected from alkyl, alkenyl, cycloalkyl, and aryl, or R.sup.1 and R.sup.2 together and R.sup.3 and R.sup.4 together form a ring structure having from 4 to 10 carbon atoms, or in structure III, R.sup.5, R.sup.6, R.sup.7, and R.sup.8 are each independently selected from alkyl, alkenyl, cycloalkyl, and aryl, or R.sup.5 and R.sup.6 together and R.sup.7 and R.sup.8 together form a ring structure having from 4 to 10 carbon atoms, at a temperature of between about 100.degree. and 250.degree. C. for between about 1 hr and 300 days in the absence of N.sub.2. The surprisingly stable catalyst is a complex of an organic ligand comprising H, C, Si, N, P atoms, and a platinum group metal. The dehydrogenation is performed between about 100 to 200.degree. C., and has increased turnover.

  8. Moessbauer spectra of ferrite catalysts used in oxidative dehydrogenation

    Science.gov (United States)

    Cares, W. R.; Hightower, J. W.

    1971-01-01

    Room temperature Mossbauer spectroscopy was used to examine bulk changes which occur in low surface area CoFe2O4 and CuFe2O4 catalysts as a result of contact with various mixtures of trans-2-butene and O2 during oxidative dehydrogenation reactions at about 420 C. So long as there was at least some O2 in the gas phase, the CoFe2O4 spectrum was essentially unchanged. However, the spectrum changed from a random spinel in the oxidized state to an inverse spinel as it was reduced by oxide ion removal. The steady state catalyst lies very near the fully oxidized state. More dramatic solid state changes occurred as the CuFe2O4 underwent reduction. Under severe reduction, the ferrite was transformed into Cu and Fe3O4, but it could be reversibly recovered by oxidation. An intense doublet located near zero velocity persisted in all spectra of CuFe2O4 regardless of the state of reduction.

  9. A New Homogeneous Catalyst for the Dehydrogenation of Dimethylamine Borane Starting with Ruthenium(III Acetylacetonate

    Directory of Open Access Journals (Sweden)

    Ebru Ünel Barın

    2015-06-01

    Full Text Available The catalytic activity of ruthenium(III acetylacetonate was investigated for the first time in the dehydrogenation of dimethylamine borane. During catalytic reaction, a new ruthenium(II species is formed in situ from the reduction of ruthenium(III and characterized using UV-Visible, Fourier transform infrared (FTIR, 1H NMR, and mass spectroscopy. The most likely structure suggested for the ruthenium(II species is mer-[Ru(N2Me43(acacH]. Mercury poisoning experiment indicates that the catalytic dehydrogenation of dimethylamine-borane is homogeneous catalysis. The kinetics of the catalytic dehydrogenation of dimethylamine borane starting with Ru(acac3 were studied depending on the catalyst concentration, substrate concentration and temperature. The hydrogen generation was found to be first-order with respect to catalyst concentration and zero-order regarding the substrate concentration. Evaluation of the kinetic data provides the activation parameters for the dehydrogenation reaction: the activation energy Ea = 85 ± 2 kJ·mol−1, the enthalpy of activation ∆H# = 82 ± 2 kJ·mol−1 and the entropy of activation; ∆S# = −85 ± 5 J·mol−1·K−1. The ruthenium(II catalyst formed from the reduction of ruthenium(III acetylacetonate provides 1700 turnovers over 100 hours in hydrogen generation from the dehydrogenation of dimethylamine borane before deactivation at 60 °C.

  10. Iodine Deficiency

    Science.gov (United States)

    ... 2017 By ATA | Featured , Iodine Deficiency , News Releases , Potassium Iodide (KI) | No Comments IDD NEWSLETTER – February 2017 VOLUME ... 2016 By ATA | Featured , Iodine Deficiency , News Releases , Potassium Iodide (KI) | No Comments IDD NEWSLETTER – November 2015 (PDF ...

  11. Oxidative dehydrogenation of ethane to ethylene using vanadia based catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Qiao, Ailing; Kalevaru, V.N. [Univ. Rostock e.V., Rostock (Germany). Leibniz-Inst. fuer Katalyse; Humar, A.S.; Lingaiah, N.; Sai Prasad, P.S.; Martin, A. [Indian Institute of Chemical Technology, Hyderabad (India). Inorganic and Physical Chemistry Div.

    2011-07-01

    In this work, we describe the application of V{sub 2}O{sub 5}/Nb{sub 2}O{sub 5} catalysts for the oxidative dehydrogenation (ODH) of ethane to ethylene. A series of Nb{sub 2}O{sub 5} supported V{sub 2}O{sub 5} catalysts were prepared by impregnation technique. NH{sub 4}VO{sub 3} was used as a precursor for V{sub 2}O{sub 5}. The content of V{sub 2}O{sub 5} is varied in the range from 5 to 20 wt%. Catalytic tests were carried out in a fixed bed quartz reactor in the temperature range from 500 to 600 C. The conversion of ethane has been increased from ca. 20 to 35 % with increase in temperature from 500 to 600 C, while the yield of ethylene is increased from about 5 to 12 % only. CO and CO{sub 2} are the only major by-products of the reaction. The activity tests were performed at low O{sub 2} concentration in the feed and hence low conversions were achieved. Furthermore, the conversion of ethane is found to increase continuously with increase in V{sub 2}O{sub 5} loading while the yield of C{sub 2}H{sub 4} increased only up to 10wt% V{sub 2}O{sub 5} and then decreased. Results revealed that the catalytic activity and selectivity is found to depend on the V{sub 2}O{sub 5} loading. Among all, 10wt% V{sub 2}O{sub 5}/Nb{sub 2}O{sub 5} catalyst has displayed the superior performance. (orig.)

  12. Dehydrogenation characteristics of MgnH2n (n = 1-32) nanoclusters: A first-principles DFT study

    Science.gov (United States)

    Banerjee, P.; Chandrakumar, K. R. S.; Das, G. P.

    2015-06-01

    Ground state structures and dehydrogenation characteristics of MgnH2n (n = 1-32) nanoclusters have been investigated using first principles DFT approach. Dehydrogenation temperature gets reduced compared to the bulk rutile phase of MgH2, indicating its favorable usage for hydrogen storage.

  13. Experimental and Theoretical Mechanistic Investigation of the Iridium-Catalyzed Dehydrogenative Decarbonylation of Primary Alcohols

    DEFF Research Database (Denmark)

    Olsen, Esben Paul Krogh; Singh, Thishana; Harris, Pernille

    2015-01-01

    cycles. One carbon monoxide ligand was shown to remain coordinated to iridium throughout the reaction, and release of carbon monoxide was suggested to occur from a dicarbonyl complex. IrH2Cl(CO)(rac-BINAP) was also synthesized and detected in the dehydrogenation of benzyl alcohol. In the same experiment......, IrHCl2(CO)(rac-BINAP) was detected from the release of HCl in the dehydrogenation and subsequent reaction with IrCl(CO)(rac-BINAP). This indicated a substitution of chloride with the alcohol to form a square planar iridium alkoxo complex that could undergo a beta-hydride elimination. A KIE of 1......The mechanism for the iridium-BINAP catalyzed dehydrogenative decarbonylation of primary alcohols with the liberation of molecular hydrogen and carbon monoxide was studied experimentally and computationally. The reaction takes place by tandem catalysis through two catalytic cycles involving...

  14. Tris(pentafluorophenyl)borane-Catalyzed Acceptorless Dehydrogenation of N-Heterocycles.

    Science.gov (United States)

    Kojima, Masahiro; Kanai, Motomu

    2016-09-26

    Catalytic acceptorless dehydrogenation is an environmentally benign way to desaturate organic compounds. This process is traditionally accomplished with transition-metal-based catalysts. Herein, a borane-catalyzed, metal-free acceptorless dehydrogenation of saturated N-heterocycles is disclosed. Tris(pentafluorophenyl)borane was identified as a versatile catalyst, which afforded several synthetically important N-heteroarenes in up to quantitative yield. Specifically, the present metal-free catalytic system exhibited a uniquely high tolerance toward sulfur functionalities, and demonstrated superior reactivity in the synthesis of benzothiazoles compared to conventional metal-catalyzed systems. This protocol can thus be regarded as the first example of metal-free acceptorless dehydrogenation in synthetic organic chemistry.

  15. Theoretical investigation of the mechanism of tritiated methane dehydrogenation reaction using nickel-based catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Liang; Li, Jiamao; Deng, Bing; Yang, Yong; Wang, Heyi [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Li, Weiyi [School of Physics and Chemistry, Xihua University, Chengdu 610065 (China); Li, Shuo, E-mail: lishuo@cqut.edu.cn [School of Chemical Engineering, Chongqing University of Technology, Chongqing 400054 (China); Tan, Zhaoyi, E-mail: tanzhaoyi@caep.cn [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China)

    2015-06-15

    Graphical abstract: - Highlights: • Four-step dehydrogenation of CT{sub 4} catalyzed by Ni to form Ni–C by releasing T{sub 2}. • The process of Ni + CT{sub 4} → NiCT{sub 2} + T{sub 2} is more achievable than that of NiCT{sub 2} → NiC + T{sub 2}. • TNiCT → T{sub 2}NiC step is the RDS with the rate constant of k = 2.8 × 10{sup 13} exp(−313,136/RT). • The hydrogen isotope effect value of k{sub H}/k{sub T} is 2.94, and k{sub D}/k{sub T} is 1.39. • CH{sub 4} and CD{sub 4} dehydrogenations are likely to occur, accompanied by the CT{sub 4} cracking. - Abstract: The mechanism of tritiated methane dehydrogenation reaction catalyzed by nickel-based catalyst was investigated in detail by density functional theory (DFT) at the B3LYP/[6-311++G(d, p), SDD] level. The computational results indicated that the dehydrogenation of tritiated methane is endothermic. The decomposition of tritiated methane catalyzed by Ni to form Ni-based carbon (Ni–C) after a four-step dehydrogenation companied with releasing tritium. After the first and second dehydrogenation steps, Ni + CT{sub 4} formed NiCT{sub 2}. After the third and fourth dehydrogenation steps, NiCT{sub 2} formed NiC. The first and second steps of dehydrogenation occurred on both the singlet and triplet states, and the lowest energy route is Ni + CT{sub 4} → {sup 1}COM → {sup 1}TS1 → {sup 3}IM1 → {sup 3}TS2 → {sup 3}IM2. The third and fourth steps of dehydrogenation occurred on both the singlet and quintet states, and the minimum energy reaction pathway appeared to be IM3 → {sup 1}TS4 → {sup 5}IM4 → {sup 5}TS5 → {sup 5}IM5 → {sup 5}pro + T{sub 2}. The fourth step of dehydrogenation TNiCT → T{sub 2}NiC was the rate-determining step of the entire reaction with the rate constant of k{sub 2} = 2.8 × 10{sup 13} exp(−313,136/RT) (in cm{sup 3} mol{sup −1} s{sup −1}), and its activation energy barrier was calculated to be 51.8 kcal/mol. The Ni-catalyzed CH{sub 4} and CD{sub 4} cracking

  16. Communication: Visualization and spectroscopy of defects induced by dehydrogenation in individual silicon nanocrystals

    Science.gov (United States)

    Kislitsyn, Dmitry A.; Mills, Jon M.; Kocevski, Vancho; Chiu, Sheng-Kuei; DeBenedetti, William J. I.; Gervasi, Christian F.; Taber, Benjamen N.; Rosenfield, Ariel E.; Eriksson, Olle; Rusz, Ján; Goforth, Andrea M.; Nazin, George V.

    2016-06-01

    We present results of a scanning tunneling spectroscopy (STS) study of the impact of dehydrogenation on the electronic structures of hydrogen-passivated silicon nanocrystals (SiNCs) supported on the Au(111) surface. Gradual dehydrogenation is achieved by injecting high-energy electrons into individual SiNCs, which results, initially, in reduction of the electronic bandgap, and eventually produces midgap electronic states. We use theoretical calculations to show that the STS spectra of midgap states are consistent with the presence of silicon dangling bonds, which are found in different charge states. Our calculations also suggest that the observed initial reduction of the electronic bandgap is attributable to the SiNC surface reconstruction induced by conversion of surface dihydrides to monohydrides due to hydrogen desorption. Our results thus provide the first visualization of the SiNC electronic structure evolution induced by dehydrogenation and provide direct evidence for the existence of diverse dangling bond states on the SiNC surfaces.

  17. In situ Raman spectroscopy study of metal-enhanced hydrogenation and dehydrogenation of VO2

    Science.gov (United States)

    Wu, Hao; Fu, Qiang; Bao, Xinhe

    2016-11-01

    Vanadium dioxide (VO2) has a phase transition from insulator to metal at 340 K, and this transition can be strongly modified by hydrogenation. In this work, two dimensional (2D) VO2 sheets have been grown on Si(1 1 1) surfaces through chemical vapor deposition, and metal (Au, Pt) thin films were deposited on VO2 surfaces by sputtering. The hydrogenation and dehydrogenation of VO2 and metal-decorated VO2 structures in H2 and in air were in situ studied by Raman. We found that hydrogenation and dehydrogenation temperatures have been significantly decreased with the VO2 surface decorated by Au and Pt. The enhanced hydrogenation and dehydrogenation reactions can be attributed to catalytic dissociation of H2 and O2 molecules on metal surfaces and subsequent spillover of dissociated H and O atoms to the oxide surfaces.

  18. Uniform dehydrogenation of amorphous silicon thin films using a wide thermal annealing system

    Science.gov (United States)

    Jung, Yong Chan; Seong, Sejong; Lee, Taehoon; Ahn, Jinho; Kim, Tae Hyun; Yeo, Won-Jae; Park, In-Sung

    2017-02-01

    To prevent ablation caused by sudden hydrogen eruption during crystallization of hydrogenated amorphous Si (a-Si:H) thin films, a wide dehydrogenation thermal annealing (wDTA) system was developed to reduce hydrogen content in a-Si:H film prior to its crystallization process. The annealed a-Si:H films were fully dehydrogenated and nanocrystallized by the wDTA system. Raman scattering measurement revealed that the dehydrogenation process lowers the hydrogen content through disappearance of the peak intensity at 2000 cm-1. The a-Si:H film was transformed into nanocrystallized Si with lower residual stress. The major advantage of this wDTA was the large area uniformity of the thermal and the resulting material properties for 8 generation display. The uniform material characteristics of the hydrogen content, thickness, energy bandgap, and transmittance of the annealed Si films in the overall area was confirmed by Raman spectroscopy, spectroscopic ellipsometry, and UV-vis spectrometer measurement.

  19. Hydrogenation/Dehydrogenation Performances of the MgH2-WS2 Composites

    Institute of Scientific and Technical Information of China (English)

    WANG Jiasheng; ZHANG Wei; CHENG Ying; KE Dandan; HAN Shumin

    2015-01-01

    The hydrogenation/dehydrogenation kinetics and thermodynamic behaviors of the MgH2-WS2 composites were investigated. The TPD (Temperature-Programmed-Desorption) curves showed that the onset dehydrogenation temperature of the MgH2 + 20wt% WS2 composite was 615 K, 58 K lower than that of the pristine MgH2. The kinetic measurements showed that within 21 min, the MgH2 + 20wt% WS2 composite could absorb 2.818wt% at 423 K, and release 4.244 wt% of hydrogen at 623 K, while the hydriding/dehydriding capacity of MgH2 reached only 0.979wt% and 2.319wt% respectively under identical conditions. The improvement of hydrogenation/dehydrogenation performances for the composite was attributed to the co-catalytic effect between the new phases W and MgS which formed during the ball-milling process.

  20. Role of Ti doping and Al and B vacancies in the dehydrogenation of Al(BH₄)₃

    Indian Academy of Sciences (India)

    INDRANI CHOUDHURI; ARUP MAHATA; KUBER SINGH RAWAT; BISWARUP PATHAK

    2016-10-01

    Metal borohydrides such as Al(BH₄)₃ is thermodynamically very stable but has weak dehydrogenation property. In contrast, Ti(BH₄)₃ has less stability (25◦C) but excellent dehydrogenation property. Hence, we have studied Ti-doped aluminium borohydride systems in order to improve the dehydrogenation property. Our density functional studies (DOS and pDOS) show that Ti interacts more strongly with the BH₄ unit and such strong interaction weakens the B-H bond and improves the dehydrogenation property. Ti-doped Al(BH₄)₃ system improves the overall stability due to the formation of a stronger Ti-B bond. Our study on defects in Al(BH₄)₃ suggests that B-defect system has the best dehydrogenation property compared to the pure and Ti-doped Al(BH₄)₃ systems.

  1. Aerobic dehydrogenation of cyclohexanone to cyclohexenone catalyzed by Pd(DMSO)2(TFA)2: evidence for ligand-controlled chemoselectivity.

    Science.gov (United States)

    Diao, Tianning; Pun, Doris; Stahl, Shannon S

    2013-06-05

    The dehydrogenation of cyclohexanones affords cyclohexenones or phenols via removal of 1 or 2 equiv of H2, respectively. We recently reported several Pd(II) catalyst systems that effect aerobic dehydrogenation of cyclohexanones with different product selectivities. Pd(DMSO)2(TFA)2 is unique in its high chemoselectivity for the conversion of cyclohexanones to cyclohexenones, without promoting subsequent dehydrogenation of cyclohexenones to phenols. Kinetic and mechanistic studies of these reactions reveal the key role of the dimethylsulfoxide (DMSO) ligand in controlling this chemoselectivity. DMSO has minimal kinetic influence on the rate of Pd(TFA)2-catalyzed dehydrogenation of cyclohexanone to cyclohexenone, while it strongly inhibits the second dehydrogenation step, conversion of cyclohexenone to phenol. These contrasting kinetic effects of DMSO provide the basis for chemoselective formation of cyclohexenones.

  2. Oxidative dehydrogenation of isobutane over supported V–Mo mixed oxides

    Directory of Open Access Journals (Sweden)

    IOAN-CEZAR MARCU

    2010-08-01

    Full Text Available Vanadium–molybdenum oxides supported on Al2O3, CeO2 and TiO2 were prepared by a “wet” impregnation method, characterized using XRD, N2 adsorption, UV–Vis spectroscopy, electrical conductivity measurements and tested in the oxidative dehydrogenation of isobutane. The catalytic performance in the oxidative dehydrogenation of isobutane at 400–550 °C depended on the nature of support and on the content of VMoO species on the support. The catalysts supported on alumina were more active and selective than those supported on ceria and titania.

  3. Mechanistic insights into the oxidative dehydrogenation of amines to nitriles in continuous flow

    DEFF Research Database (Denmark)

    Corker, Emily C.; Ruiz-Martínez, Javier; Riisager, Anders;

    2015-01-01

    The oxidative dehydrogenation of various aliphatic amines to their corresponding nitrile compounds using RuO2/Al2O3 catalysts in air was successfully applied to a continuous flow reaction. Conversions of amines (up to >99%) and yields of nitriles (up to 77%) varied depending on reaction conditions...... and the amine utilised. The presence of water was found to be important for the activity and stability of the RuO2/Al2O3 catalyst. The Hammett relationship and in situ infrared spectroscopy were applied to divulge details about the catalytic mechanism of the oxidative dehydrogenation of amines over RuO2/Al2O3...

  4. Dehydrogenative Aromatization of Saturated Aromatic Compounds by Graphite Oxide and Molecular Sieves

    Institute of Scientific and Technical Information of China (English)

    张轩; 徐亮; 王希涛; 马宁; 孙菲菲

    2012-01-01

    Graphite oxide (GO) has attracted much attention of material and catalysis chemists recently. Here we describe a combination of GO and molecular sieves for the dehydrogenative aromatization. GO prepared through improved Hummers method showed high oxidative activity in this reaction. Partially or fully saturated aromatic compounds were converted to their corresponding dehydrogenated aromatic products with fair to excellent conversions and selectivities. As both GO and molecular sieves are easily available, cheap, lowly toxic and have good tolerance to various functional groups, this reaction provides a facile approach toward aromatic compounds from their saturated precursors

  5. Disaccharidase deficiency.

    Science.gov (United States)

    Bayless, T M; Christopher, N L

    1969-02-01

    This review of the literature and current knowledge concerning a nutritional disorder of disaccharidase deficiency discusses the following topics: 1) a description of disorders of disaccharide digestion; 2) some historical perspective on the laboratory and bedside advances in the past 10 years that have helped define a group of these digestive disorders; 3) a classification of conditions causing disaccharide intolerance; and 4) a discussion of some of the specific clinical syndromes emphasizing nutritional consequences of these syndromes. The syndromes described include congenital lactase deficiency, acquired lactase deficiency in teenagers and adults, acquired generalized disaccharidase deficiency secondary to diffuse mucosal damage, acquired lactose intolerance secondary to alterations in the intestinal transit, sucrase-isomaltase deficiencies, and other disease associations connected with lactase deficiency such as colitis.

  6. Cooperative dehydrogenation of N-heterocycles using a carbon nanotube-rhodium nanohybrid.

    Science.gov (United States)

    Jawale, Dhanaji V; Gravel, Edmond; Shah, Nimesh; Dauvois, Vincent; Li, Haiyan; Namboothiri, Irishi N N; Doris, Eric

    2015-05-04

    Rhodium nanoparticles were anchored on carbon nanotubes and the resulting nanohybrid was studied as co-catalyst, along with tert-butylcatechol, for the dehydrogenation of various N-heterocycles. The co-catalytic system operates in high yields, under the mildest conditions reported so far, and can be applied to a wide variety of secondary amine-containing scaffolds.

  7. Iridium‐Catalyzed Dehydrogenative Decarbonylation of Primary Alcohols with the Liberation of Syngas

    DEFF Research Database (Denmark)

    Olsen, Esben Paul Krogh; Madsen, Robert

    2012-01-01

    to excellent yields. Ethers, esters, imides, and aryl halides are stable under the reaction conditions, whereas olefins are partially saturated. The reaction is believed to proceed by two consecutive organometallic transformations that are catalyzed by the same iridium(I)–BINAP species. First, dehydrogenation...

  8. Palladium-catalyzed aerobic dehydrogenative aromatization of cyclohexanone imines to arylamines.

    Science.gov (United States)

    Hajra, Alakananda; Wei, Ye; Yoshikai, Naohiko

    2012-11-02

    Dehydrogenative aromatization of cyclohexanone imines to arylamines has been achieved using a palladium catalyst under aerobic conditions. The reaction is applicable to a variety of imines that are either preformed or generated in situ from cyclohexanone derivatives and aryl or alkylamines.

  9. Acceptorless Dehydrogenation of N-Heterocycles by Merging Visible-Light Photoredox Catalysis and Cobalt Catalysis.

    Science.gov (United States)

    He, Ke-Han; Tan, Fang-Fang; Zhou, Chao-Zheng; Zhou, Gui-Jiang; Yang, Xiao-Long; Li, Yang

    2017-03-06

    Herein, the first acceptorless dehydrogenation of tetrahydroquinolines (THQs), indolines, and other related N-heterocycles, by merging visible-light photoredox catalysis and cobalt catalysis at ambient temperature, is described. The potential applications to organic transformations and hydrogen-storage materials are demonstrated. Primary mechanistic investigations indicate that the catalytic cycle occurs predominantly by an oxidative quenching pathway.

  10. Oxidative dehydrogenation of ethylbenzene using nitrous oxide over vanadia-magnesia catalysts

    NARCIS (Netherlands)

    Shiju, N.R.; Anilkumar, M.; Gokhale, S.P.; Rao, B.S.; Satyanarayana, C.V.V.

    2011-01-01

    A series of V-Mg-O catalysts with different loadings of vanadia were prepared by the wet impregnation method and the effect of the local structure of these catalysts on the oxidative dehydrogenation of ethylbenzene with N2O was investigated. High styrene selectivity (97%) was obtained at 773 K. The

  11. Experimental and Theoretical Mechanistic Investigation of the Iridium-Catalyzed Dehydrogenative Decarbonylation of Primary Alcohols

    DEFF Research Database (Denmark)

    Olsen, Esben Paul Krogh; Singh, Thishana; Harris, Pernille;

    2015-01-01

    The mechanism for the iridium-BINAP catalyzed dehydrogenative decarbonylation of primary alcohols with the liberation of molecular hydrogen and carbon monoxide was studied experimentally and computationally. The reaction takes place by tandem catalysis through two catalytic cycles involving dehyd...... a rate-determining phosphine dissociation for the decarbonylation of aldehydes....

  12. Dehydrogenation of light alkanes over rhenium catalysts on conventional and mesoporous MFI supports

    DEFF Research Database (Denmark)

    Rovik, Anne Krogh; Hagen, Anke; Schmidt, I.;

    2006-01-01

    Recently, Re/HZSM-5 (Si/Al = 15) was shown to be an efficient catalyst for ethane dehydrogenation and aromatization at 823 K and atmospheric pressure. In this reaction, the major initial products were benzene, toluene and xylene (BTX), but increasing amounts of ethene were produced with time on s...

  13. Iridium complexes of new NCP pincer ligands: catalytic alkane dehydrogenation and alkene isomerization.

    Science.gov (United States)

    Jia, Xiangqing; Zhang, Lei; Qin, Chuan; Leng, Xuebing; Huang, Zheng

    2014-09-28

    Iridium complexes of novel NCP pincer ligands containing pyridine and phosphinite arms have been synthesized. One Ir complex shows good catalytic activity for alkane dehydrogenation, and all complexes are highly active for olefin isomerization. A combination of the Ir complex and a (PNN)Fe pincer complex catalyzes the formation of linear alkylboronates selectively from internal olefins via sequential olefin isomerization-hydroboration.

  14. Dehydrogenation of methanol on Pd(100): comparison with the results of Pd(111).

    Science.gov (United States)

    Jiang, Ruibin; Guo, Wenyue; Li, Ming; Lu, Xiaoqing; Yuan, Jianye; Shan, Honghong

    2010-07-28

    Dehydrogenation of methanol on Pd(100) is systematically investigated using self-consistent periodic density functional theory. The theoretical results are compared with those of the same reaction on Pd(111) published very recently [J. Phys. Chem. C, 2009, 113, 4188-4197]. Switching from (111) to (100), adsorptions are strengthened for most species except for CHO, CO and H at hollow sites. Moreover, Pd(100) affords relatively low energy barriers and higher rate constants for most elementary dehydrogenation steps as well as smaller desorption rates for the saturated adsorbates (methanol and formaldehyde), suggesting that the more open Pd surface indeed possesses the higher activity and selectivity for the complete dehydrogenation of methanol. At lower temperatures (e.g., 250 K), Pd(100) affords the same dehydrogenation path as Pd(111) for methanol, which is unchanged on the latter surface at both lower and higher temperatures; whereas at the typical steam re-forming (MSR) temperature (500 K), the path on Pd(100), i.e., CH(3)OH --> CH(3)O and/or CH(2)OH --> CH(2)O --> CHO --> CO, is different from the situation of Pd(111). In both cases, the initial bond scission process constitutes the rate-determining step.

  15. Application of Heterogeneous Copper Catalyst in a Continuous Flow Process: Dehydrogenation of Cyclohexanol

    Science.gov (United States)

    Glin´ski, Marek; Ulkowska, Urszula; Iwanek, Ewa

    2016-01-01

    In this laboratory experiment, the synthesis of a supported solid catalyst (Cu/SiO2) and its application in the dehydrogenation of cyclohexanol performed under flow conditions was studied. The experiment was planned for a group of two or three students for two 6 h long sessions. The copper catalyst was synthesized using incipient wetness…

  16. Non-Precious Bimetallic Catalysts for Selective Dehydrogenation of an Organic Chemical Hydride System

    KAUST Repository

    Shaikh Ali, Anaam

    2015-07-06

    Methylcyclohexane (MCH)-Toluene (TOL) chemical hydride cycles as a hydrogen carrier system is successful with the selective dehydrogenation reaction of MCH to TOL, which has been achieved only using precious Pt-based catalysts. Herein, we report improved selectivity using non-precious metal nickel-based bimetallic catalysts, where the second metal occupies the unselective step sites.

  17. Simultaneous dehydrogenation of organic compounds and hydrogen removal by hydride forming alloys

    NARCIS (Netherlands)

    Appelman, W.J.T.M.; Kuczynski, M.; Versteeg, G.F.

    1992-01-01

    The applicability of hydrogen-absorbing metals in dehydrogenation reactions was investigated. Based on thermodynamic considerations, operating ranges were defined within which an increase of the reactant conversion can he achieved owing to an in situ hydrogen removal by the alloy. Low plateau pressu

  18. Synthesis and characterization of conventional and mesoporous Ga-MFI for ethane dehydrogenation

    DEFF Research Database (Denmark)

    Leth, Karen Thrane; Rovik, Anne Krogh; Holm, Martin Spangsberg

    2008-01-01

    difference being the morphology of the crystals. The catalytic properties of the samples were tested in ethane dehydrogenation at 823 K and at atmospheric pressure. The two Ga-MFI samples differ greatly in conversion of ethane, as a result of their difference in porosity, and it is found that the conversion...

  19. Unravelling The Mechanism of Basic Aqueous Methanol Dehydrogenation Catalyzed By Ru-PNP Pincer Complexes

    DEFF Research Database (Denmark)

    Alberico, Elisabetta; Lennox, Alastair J. J.; Vogt, Lydia K.;

    2016-01-01

    Ruthenium PNP complex 1a (RuH(CO)Cl(HN(C2H4Pi-Pr2)2)) represents a state-of-the-art catalyst for low-temperature (methanol dehydrogenation to H2 and CO2. Herein, we describe an investigation that combines experiment, spectroscopy, and theory to provide a mechanistic rationale...

  20. Iodine Deficiency

    NARCIS (Netherlands)

    Zimmermann, M.B.

    2009-01-01

    Iodine deficiency has multiple adverse effects in humans, termed iodine deficiency disorders, due to inadequate thyroid hormone production. Globally, it is estimated that 2 billion individuals have an insufficient iodine intake, and South Asia and sub-Saharan Africa are particularly affected. Howeve

  1. CHARACTERIZING THE INFRARED SPECTRA OF SMALL, NEUTRAL, FULLY DEHYDROGENATED POLYCYCLIC AROMATIC HYDROCARBONS

    Energy Technology Data Exchange (ETDEWEB)

    Mackie, C. J.; Peeters, E.; Cami, J. [Department of Physics and Astronomy, University of Western Ontario, London, ON N6A 3K7 (Canada); Bauschlicher, C. W. Jr., E-mail: mackie@strw.leidenuniv.nl [NASA Ames Research Center, MS 245-6, Moffett Field, CA 94035 (United States)

    2015-02-01

    We present the results of a computational study to investigate the infrared spectroscopic properties of a large number of polycyclic aromatic hydrocarbon (PAH) molecules and their fully dehydrogenated counterparts. We constructed a database of fully optimized geometries for PAHs that is complete for eight or fewer fused benzene rings, thus containing 1550 PAHs and 805 fully dehydrogenated aromatics. A large fraction of the species in our database have clearly non-planar or curved geometries. For each species, we determined the frequencies and intensities of their normal modes using density functional theory calculations. Whereas most PAH spectra are fairly similar, the spectra of fully dehydrogenated aromatics are much more diverse. Nevertheless, these fully dehydrogenated species show characteristic emission features at 5.2 μm, 5.5 μm, and 10.6 μm; at longer wavelengths, there is a forest of emission features in the 16-30 μm range that appears as a structured continuum, but with a clear peak centered around 19 μm. We searched for these features in Spitzer-IRS spectra of various positions in the reflection nebula NGC 7023. We find a weak emission feature at 10.68 μm in all positions except that closest to the central star. We also find evidence for a weak 19 μm feature at all positions that is not likely due to C{sub 60}. We interpret these features as tentative evidence for the presence of a small population of fully dehydrogenated PAHs, and discuss our results in the framework of PAH photolysis and the formation of fullerenes.

  2. Spontaneous dehydrogenation of methanol over defect-free MgO(100) thin film deposited on molybdenum

    CERN Document Server

    Song, Zhenjun

    2016-01-01

    The dehydrogenation reaction of methanol on metal supported MgO(100) films has been studied by employing periodic density functional calculations. As far as we know, the dehydrogenation of single methanol molecule over inert oxide insulators such as MgO has never been realized before without the introduction of defects and low coordinated atoms. By depositing the very thin oxide films on Mo substrate we have successfully obtained the dissociative state of methanol. The dehydrogenation reaction is energetically exothermic and nearly barrierless. The metal supported thin oxide films studied here provide a versatile approach to enhance the activity and properties of oxides.

  3. CO2 emission free co-generation of energy and ethylene in hydrocarbon SOFC reactors with a dehydrogenation anode.

    Science.gov (United States)

    Fu, Xian-Zhu; Lin, Jie-Yuan; Xu, Shihong; Luo, Jing-Li; Chuang, Karl T; Sanger, Alan R; Krzywicki, Andrzej

    2011-11-21

    A dehydrogenation anode is reported for hydrocarbon proton conducting solid oxide fuel cells (SOFCs). A Cu-Cr(2)O(3) nanocomposite is obtained from CuCrO(2) nanoparticles as an inexpensive, efficient, carbon deposition and sintering tolerant anode catalyst. A SOFC reactor is fabricated using a Cu-Cr(2)O(3) composite as a dehydrogenation anode and a doped barium cerate as a proton conducting electrolyte. The protonic membrane SOFC reactor can selectively convert ethane to valuable ethylene, and electricity is simultaneously generated in the electrochemical oxidative dehydrogenation process. While there are no CO(2) emissions, traces of CO are present in the anode exhaust when the SOFC reactor is operated at over 700 °C. A mechanism is proposed for ethane electro-catalytic dehydrogenation over the Cu-Cr(2)O(3) catalyst. The SOFC reactor also has good stability for co-generation of electricity and ethylene at 700 °C.

  4. Theoretical Studies on Dehydrogenation Reactions in Mg2(BH4)2(NH2)2 Compounds

    Institute of Scientific and Technical Information of China (English)

    Zheng Chen; Zhe-ning Chen; An-an Wu; Guo-tao Wu; Zhi-tao Xiong; Ping Chen; Xin Xu

    2012-01-01

    Borohydrides have been recently hightlighted as prospective new materials due to their high gravimetric capacities for hydrogen storage.It is,therefore,important to understand the underlying dehydrogenation mechanisms for further development of these materials.We present a systematic theoretical investigation on the dehydrogenation mechanisms of the Mg2(BH4)2(NH2)2 compounds.We found that dehydrogenation takes place most likely via the intermolecular process,which is favorable both kinetically and thermodynamically in comparison with that of the intramolecular process.The dehydrogenation of Mg2(BH4)2(NH2)2 initially takes place via the direct combination of the hydridic H in BH4-and the protic H in NH2-,followed by the formation of Mg-H and subsequent ionic recombination of Mg-Hδ-… Hδ+-N.

  5. Mechanisms for dehydrogenation and hydrogenation of N-heterocycles using PNP-pincer-supported iron catalysts: a density functional study.

    Science.gov (United States)

    Sawatlon, Boodsarin; Surawatanawong, Panida

    2016-10-14

    The catalytic dehydrogenation and hydrogenation of N-heterocycles have potential applications in organic hydrogen storage. Recently, Fe(HPNP)(CO)(H)(HBH3) (cp1) and Fe(HPNP)(CO)(H)(Br) (cp2), the iron(ii) complexes supported by bis(phosphino)amine pincer (Fe-PNP) (PNP = N(CH2CH2P(i)Pr2)2), have been reported to be the starting complexes which can catalyze the dehydrogenation and hydrogenation of N-heterocycles. The active species were proposed to be the trans-dihydride complexes, Fe(HPNP)(CO)(H)2 (cp4) and Fe(PNP)(CO)(H) (cp3), which can be interconverted. Here, our density functional study revealed that the N-heterocyclic substrate plays a role in the formation of cp4 from cp1, while the tert-butoxide base assists with the formation of cp3 from cp2. The mechanism for cp3 catalyzed dehydrogenation of a 1,2,3,4-tetrahydroquinoline (THQ) substrate to quinoline (Q) involves two main steps: (i) dehydrogenation of THQ to 3,4-dihydroquinoline (34DHQ) and (ii) dehydrogenation of 34DHQ to Q. In each dehydrogenation step, the proton is transferred from the substrate to the N of the PNP ligand of cp3. An ion-pair complex between Fe-PNP and the deprotonated substrate is then formed before the hydride at the adjacent C is transferred to Fe. Notably, the isomerization of 34DHQ to 14DHQ or 12DHQ is not necessary, as the bifunctionality of Fe-PNP in cp3 can stabilize the ion-pair complex and facilitate direct dehydrogenation of the C3-C4 bond in 34DHQ. On the other hand, the mechanism for hydrogenation of Q involves the initial formation of 14DHQ, which can easily isomerize to 34DHQ with the assistance of a tert-butoxide base. Finally, 34DHQ is dehydrogenated to THQ. As the overall energy barriers for cp3 catalyzed dehydrogenation of THQ (+27.6 kcal mol(-1)) and cp4 catalyzed hydrogenation of Q (+23.8 kcal mol(-1)) are only slightly different, reaction conditions can be conveniently adjusted to favor either the dehydrogenation or hydrogenation process. Insights into the role of

  6. Iron deficiency.

    Science.gov (United States)

    Scrimshaw, N S

    1991-10-01

    The world's leading nutritional problem is iron deficiency. 66% of children and women aged 15-44 years in developing countries have it. Further, 10-20% of women of childbearing age in developed countries are anemic. Iron deficiency is identified with often irreversible impairment of a child's learning ability. It is also associated with low capacity for adults to work which reduces productivity. In addition, it impairs the immune system which reduces the body's ability to fight infection. Iron deficiency also lowers the metabolic rate and the body temperature when exposed to cold. Hemoglobin contains nearly 73% of the body's iron. This iron is always being recycled as more red blood cells are made. The rest of the needed iron does important tasks for the body, such as binds to molecules that are reservoirs of oxygen for muscle cells. This iron comes from our diet, especially meat. Even though some plants, such as spinach, are high in iron, the body can only absorb 1.4-7% of the iron in plants whereas it can absorb 20% of the iron in red meat. In many developing countries, the common vegetarian diets contribute to high rates of iron deficiency. Parasitic diseases and abnormal uterine bleeding also promote iron deficiency. Iron therapy in anemic children can often, but not always, improve behavior and cognitive performance. Iron deficiency during pregnancy often contributes to maternal and perinatal mortality. Yet treatment, if given to a child in time, can lead to normal growth and hinder infections. However, excess iron can be damaging. Too much supplemental iron in a malnourished child promotes fatal infections since the excess iron is available for the pathogens use. Many countries do not have an effective system for diagnosing, treating, and preventing iron deficiency. Therefore a concerted international effort is needed to eliminate iron deficiency in the world.

  7. Experimental Study of Interfacial Friction in NaBH{sub 4} Solution in Microchannel Dehydrogenation Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Seok Hyun; Hwang, Sueng Sik; Lee, Hee Joon [Kookmin Univ., Seoul (Korea, Republic of)

    2014-02-15

    Sodium borohydride (NaBH{sub 4}) is considered as a secure metal hydride for hydrogen storage and supply. In this study, the interfacial friction of two-phase flow in the dehydrogenation of aqueous NaBH{sub 4} solution in a microchannel with a hydraulic diameter of 461 μm is investigated for designing a dehydrogenation chemical reactor flow passage. Because hydrogen gas is generated by the hydrolysis of NaBH{sub 4} in the presence of a ruthenium catalyst, two different flow phases (aqueous NaBH{sub 4} solution and hydrogen gas) exist in the channel. For experimental studies, a microchannel was fabricated on a silicon wafer substrate, and 100-nm ruthenium catalyst was deposited on three sides of the channel surface. A bubbly flow pattern was observed. The experimental results indicate that the two-phase multiplier increases linearly with the void fraction, which depends on the initial concentration, reaction rate, and flow residence time.

  8. Dehydrogenation of Isobutane with Carbon Dioxide over SBA-15-Supported Vanadium Oxide Catalysts

    Directory of Open Access Journals (Sweden)

    Chunling Wei

    2016-10-01

    Full Text Available A series of vanadia catalysts supported on SBA-15 (V/SBA with a vanadia (V content ranging from 1% to 11% were prepared by an incipient wetness method. Their catalytic behavior in the dehydrogenation of isobutane to isobutene with CO2 was examined. The catalysts were characterized by N2 adsorption, X-ray diffraction (XRD, scanning electron microscopy (SEM, Raman spectroscopy, and temperature-programmed reduction (TPR. It was found that these catalysts were effective for the dehydrogenation reaction, and the catalytic activity is correlated with the amount of dispersed vanadium species on the SBA-15 support. The 7% V/SBA catalyst shows the highest activity, which gives 40.8% isobutane conversion and 84.8% isobutene selectivity. The SBA-15-supported vanadia exhibits higher isobutane conversion and isobutene selectivity than the MCM-41-supported one.

  9. Excellent catalytic effects of highly crumpled graphene nanosheets on hydrogenation/dehydrogenation of magnesium hydride

    Science.gov (United States)

    Liu, Guang; Wang, Yijing; Xu, Changchang; Qiu, Fangyuan; An, Cuihua; Li, Li; Jiao, Lifang; Yuan, Huatang

    2013-01-01

    Highly crumpled graphene nanosheets (GNS) with a BET surface area as high as 1159 m2 g-1 was fabricated by a thermal exfoliation method. A systematic investigation was performed on the hydrogen sorption properties of MgH2-5 wt% GNS nanocomposites acquired by ball-milling. It was found that the as-synthesized GNS exhibited a superior catalytic effect on hydrogenation/dehydrogenation of MgH2. Differential Scanning Calorimetry (DSC) and isothermal hydrogenation/dehydrogenation measurements indicated that both hydrogen sorption capacity and dehydrogenation/hydrogenation kinetics of the composites improved with increasing milling time. The composites MgH2-GNS milled for 20 h can absorb 6.6 wt% H2 within 1 min at 300 °C and 6.3 wt% within 40 min at 200 °C, even at 150 °C, it can also absorb 6.0 wt% H2 within 180 min. It was also demonstrated that MgH2-GNS-20 h could release 6.1 wt% H2 at 300 °C within 40 min. In addition, microstructure measurements based on XRD, SEM, TEM as well as Raman spectra revealed that the grain size of thus-prepared MgH2-GNS nanocomposites decreased with increasing milling time, moreover, the graphene layers were broken into smaller graphene nanosheets in a disordered and irregular manner during milling. It was confirmed that these smaller graphene nanosheets on the composite surface, providing more edge sites and hydrogen diffusion channels, prevented the nanograins from sintering and agglomerating, thus, leading to promotion of the hydrogenation/dehydrogenation kinetics of MgH2.Highly crumpled graphene nanosheets (GNS) with a BET surface area as high as 1159 m2 g-1 was fabricated by a thermal exfoliation method. A systematic investigation was performed on the hydrogen sorption properties of MgH2-5 wt% GNS nanocomposites acquired by ball-milling. It was found that the as-synthesized GNS exhibited a superior catalytic effect on hydrogenation/dehydrogenation of MgH2. Differential Scanning Calorimetry (DSC) and isothermal hydrogenation/dehydrogenation

  10. Kinetics of the Oxidative Dehydrogenation of Propane over a VMgO Catalyst

    Institute of Scientific and Technical Information of China (English)

    L. L(a)te; E.A. Blekkan

    2002-01-01

    The reaction kinetics of the oxidative dehydrogenation of propane was studied at 475-550℃over a VMgO catalyst. Vanadium-magnesium-oxides are among the most selective and active catalysts forthe dehydrogenation of propane to propylene. Selectivity to propylene up to about 60% was obtained at10% conversion, but the selectivity decreased with increasing conversion. No oxygenates were detected, theonly by-products were CO and CO2. The reaction rate of propane was found to be first order in propaneand close to zero order in oxygen, which is in agreement with a Mars van Krevelen mechanism with theactivation of the hydrocarbon as the rate determining step. The activation energy of the conversion ofpropane was found to be 122±6 kJ/mol.

  11. Kinetics of Oxidative Dehydrogenation of Propance over a VMgO Catalyst

    Institute of Scientific and Technical Information of China (English)

    L.Late; E.A.Blekkan

    2002-01-01

    The reaction kinetics of the oxidative dehydrogenation of propane was studied at 475-550℃ over a VMgO catalyst,Vanadium-magnesium-oxides are among the moste selective and active catalysts for the dehydrogenation of propance to propylene Selectivity to propylene up to about 60% was obtained at 10% conversion ,but the selectivity decreased with increasing conversion.No oxygenates were detected,the only by-products were CO and CO2 ,The reaction rate of propane was found to be first order in propane and close to zero order in oxygen ,which is in agreement with a Mars van Krevelen mechanism with the activation of the hydrocarbon as the rate detemining step.The activation energy,of the conversion of propane was found to be 122±6 kJ/mol.

  12. A dehydrogenation mechanism of metal hydrides based on interactions between Hdelta+ and H-.

    Science.gov (United States)

    Lu, Jun; Fang, Zhigang Zak; Sohn, Hong Yong

    2006-10-16

    This paper describes a reaction mechanism that explains the dehydrogenation reactions of alkali and alkaline-earth metal hydrides. These light metal hydrides, e.g., lithium-based compounds such as LiH, LiAlH4, and LiNH2, are the focus of intense research recently as the most promising candidate materials for on-board hydrogen storage applications. Although several interesting and promising reactions and materials have been reported, most of these reported reactions and materials have been discovered by empirical means because of a general lack of understanding of any underlying principles. This paper describes an understanding of the dehydrogenation reactions on the basis of the interaction between negatively charged hydrogen (H-, electron donor) and positively charged hydrogen (Hdelta+, electron acceptor) and experimental evidence that captures and explains many observations that have been reported to date. This reaction mechanism can be used as a guidance for screening new material systems for hydrogen storage.

  13. Role of catalysts in dehydrogenation of MgH2 nanoclusters.

    Science.gov (United States)

    Larsson, Peter; Araújo, C Moysés; Larsson, J Andreas; Jena, Puru; Ahuja, Rajeev

    2008-06-17

    A fundamental understanding of the role of catalysts in dehydrogenation of MgH(2) nanoclusters is provided by carrying out first-principles calculations based on density functional theory. It is shown that the transition metal atoms Ti, V, Fe, and Ni not only lower desorption energies significantly but also continue to attract at least four hydrogen atoms even when the total hydrogen content of the cluster decreases. In particular, Fe is found to migrate from the surface sites to the interior sites during the dehydrogenation process, releasing more hydrogen as it diffuses. This diffusion mechanism may account for the fact that a small amount of catalysts is sufficient to improve the kinetics of MgH(2), which is essential for the use of this material for hydrogen storage in fuel-cell applications.

  14. Titania-catalysed oxidative dehydrogenation of ethyl lactate: effective yet selective free-radical oxidation

    NARCIS (Netherlands)

    Ramos-Fernandez, E.V.; Geels, N.J.; Shiju, N.R.; Rothenberg, G.

    2014-01-01

    We research here the catalytic oxidative dehydrogenation of ethyl lactate, as an alternative route to ethyl pyruvate. Testing various solid catalysts (Fe2O3, TiO2, V2O5/MgO-Al2O3, ZrO2, CeO2 and ZnO), we find that simple and inexpensive TiO2 efficiently catalyses this reaction under mild conditions.

  15. Crystal-phase control of molybdenum carbide nanobelts for dehydrogenation of benzyl alcohol.

    Science.gov (United States)

    Li, Zhongcheng; Chen, Chunhui; Zhan, Ensheng; Ta, Na; Li, Yong; Shen, Wenjie

    2014-05-04

    Belt-shaped molybdenum carbides in α- and β-phases were synthesized by reducing and carburizing a nano-sized α-MoO3 precursor with hydrocarbon-hydrogen mixtures at appropriate temperatures; the β-Mo2C nanobelts with a higher fraction of coordinatively unsaturated Mo sites were more active than the α-MoC1-x nanobelts in dehydrogenation of benzyl alcohol to benzaldehyde.

  16. Selection of mixed conducting oxides for oxidative dehydrogenation of propane with pulse experiments

    NARCIS (Netherlands)

    Crapanzano, Salvatore; Babich, Igor V.; Lefferts, Leon

    2011-01-01

    In this study, propane pulse experiments at 550 °C are used as a method to select suitable oxides for further operation of catalytic dense membrane reactor (CDMR) for oxidative dehydrogenation of propane. Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF), La2NiO4+δ (LN) and PrBaCo2O5+δ (PBC) powders were used as mode

  17. First-principles calculation of dehydrogenating properties of MgH2-V systems

    Institute of Scientific and Technical Information of China (English)

    ZHOU; Dianwu; PENG; Ping; LIU; Jinshui

    2006-01-01

    Based on experimental results in which VH0.81/MgH2 interface was found during the process of mechanically milling MgH2+5at%V nanocomposite, a VH/MgH2 interface is designed and constituted in this work. A first-principles plane-wave pseudopotential method based on Density Functional Theory (DFT) has been used to investigate the vanadium alloying effects on the dehydrogenating properties of magnesium hydride, i.e., MgH2. A low absolute value of the negative heat of formation of VH/MgH2 interface compared with that of MgH2 indicates that vanadium hydrides befit to improve the dehydrogenating properties of MgH2. Based on the analysis of the density of states (DOS) and the total valence electron density distribution of MgH2 before and after V alloying, it was found that the improvement of the dehydrogenating properties of MgH2 caused by V alloying originates from the increasing of the valence electrons at Fermi level (EF) and the decreasing of the HOMO-LUMO gap (△EH-L) after V alloying. The catalysis effect of V on dehydrogenating kinetics of MgH2 may attribute to a stronger bonding between V and H atoms than that between Mg and H atoms, which leads to nucleation of the α-Mg at the VH/MgH2 interface in the MgH2-V systems easier than that in pure MgH2 phase.

  18. Highly Ordered Mesoporous Metal Oxides as Catalysts for Dehydrogenation of Cyclohexanol

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Eunok; Jin, Mingshi; Kim, Ji Man [Sungkyunkwan University, Suwon (Korea, Republic of)

    2013-08-15

    Cyclohexanone is important intermediate for the manufacture of caprolactam which is monomer of nylron. Cyclohexanone is generally produced by dehydrogenation reaction of cyclohexanol. In this study, highly mesoporous metal oxides such as meso-WO{sub 3}, meso-TiO{sub 2}, meso-Fe{sub 2}O{sub 3}, meso-CuO, meso-SnO{sub 2} and meso-NiO were synthesized using mesoporous silica KIT-6 as a hard template via nano-replication method for dehydrogenation of cyclohexanol. The overall conversion of cyclohexanol followed a general order: meso-WO{sub 3} >> meso-Fe{sub 2}O{sub 3} > meso-SnO{sub 2} > meso-TiO{sub 2} > meso-NiO > meso-CuO. In particular, meso-WO{sub 3} significantly showed higher activity than the other mesoporous metal oxides. Therefore, the meso-WO{sub 3} has wide range of application possibilities for dehydrogenation of cyclohexanol.

  19. Experimental Study and Kinetic Modeling of Decoking of Pacol Process Dehydrogenation Catalyst

    Directory of Open Access Journals (Sweden)

    M. Toghyani

    2015-07-01

    Full Text Available The Pt/γ-Al2O3 catalyst life time was limited by the formation of coke on the external and internal surfaces of catalyst in dehydrogenation reactors. The kinetics of decoking of dehydrogenation catalyst was studied in a pilot scale fixed bed reactor experimentally. The effects of temperature, oxygen concentration and other operating conditions on decoking process were investigated. A kinetic model was deve-loped to describe the decoking of mentioned catalyst. An objective function was defined as the sum of squares of the deviations among the calculated and plant data. Accordingly the appropriate values were found in order to minimize this function. It was concluded that there was a good agreement between simulation results and experimental data.  © 2015 BCREC UNDIP. All rights reservedReceived: 18th September 2014; Revised: 28th February 2015; Accepted: 9th March 2015How to Cite: Toghyani, M., Rahimi, A., Mamanpoush, M., Kazemian, R., Harandizadeh, A.H. (2015. Experimental Study and Kinetic Modeling of Decoking of Pacol Process Dehydrogenation Catalyst. Bulletin of Chemical Reaction Engineering & Catalysis, 10 (2: 155-161. (doi:10.9767/bcrec.10.2.7357.155-161 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.10.2.7357.155-161  

  20. Identifying active functionalities on few-layered graphene catalysts for oxidative dehydrogenation of isobutane.

    Science.gov (United States)

    Dathar, Gopi Krishna Phani; Tsai, Yu-Tung; Gierszal, Kamil; Xu, Ye; Liang, Chengdu; Rondinone, Adam J; Overbury, Steven H; Schwartz, Viviane

    2014-02-01

    The general consensus in the studies of nanostructured carbon catalysts for oxidative dehydrogenation (ODH) of alkanes to olefins is that the oxygen functionalities generated during synthesis and reaction are responsible for the catalytic activity of these nanostructured carbons. Identification of the highly active oxygen functionalities would enable engineering of nanocarbons for ODH of alkanes. Few-layered graphenes were used as model catalysts in experiments to synthesize reduced graphene oxide samples with varying oxygen concentrations, to characterize oxygen functionalities, and to measure the activation energies for ODH of isobutane. Periodic density functional theory calculations were performed on graphene nanoribbon models with a variety of oxygen functionalities at the edges to calculate their thermal stability and to model reaction mechanisms for ODH of isobutane. Comparing measured and calculated thermal stability and activation energies leads to the conclusion that dicarbonyls at the zigzag edges and quinones at armchair edges are appropriately balanced for high activity, relative to other model functionalities considered herein. In the ODH of isobutane, both dehydrogenation and regeneration of catalytic sites are relevant at the dicarbonyls, whereas regeneration is facile compared with dehydrogenation at quinones. The catalytic mechanism involves weakly adsorbed isobutane reducing functional oxygen and leaving as isobutene, and O2 in the feed, weakly adsorbed on the hydrogenated functionality, reacting with that hydrogen and regenerating the catalytic sites.

  1. An experimental survey of additives for improving dehydrogenation properties of magnesium hydride

    Science.gov (United States)

    Zhou, Chengshang; Fang, Zhigang Zak; Sun, Pei

    2015-03-01

    The use of a wide range of additives has been known as an important method for improving hydrogen storage properties of MgH2. There is a lack of a standard methodology, however, that can be used to select or compare the effectiveness of different additives. A systematic experimental survey was carried out in this study to compare a wide range of additives including transitions metals, transition metal oxides, hydrides, intermetallic compounds, and carbon materials, with respect to their effects on dehydrogenation properties of MgH2. MgH2 with various additives were prepared by using a high-energy-high-pressure planetary ball milling method and characterized by using thermogravimetric analysis (TGA) techniques. The results showed that additives such as Ti and V-based metals, hydride, and certain intermetallic compounds have strong catalytic effects. Additives such as Al, In, Sn, Si showed minor effects on the kinetics of the dehydrogenation of MgH2, while exhibiting moderate thermodynamic destabilizing effects. In combination, MgH2 with both kinetic and thermodynamic additives, such as the MgH2-In-TiMn2 system, exhibited a drastically decreased dehydrogenation temperature.

  2. Influence of Particle Size on Reaction Selectivity in Cyclohexene Hydrogenation and Dehydrogenation over Silica-Supported Monodisperse Pt Particles

    Energy Technology Data Exchange (ETDEWEB)

    Rioux, R. M.; Hsu, B. B.; Grass, M. E.; Song, H.; Somorjai, Gabor A.

    2008-07-11

    The role of particle size during the hydrogenation/dehydrogenation of cyclohexene (10 Torr C{sub 6}H{sub 10}, 200-600 Torr H{sub 2}, and 273-650 K) was studied over a series of monodisperse Pt/SBA-15 catalysts. The conversion of cyclohexene in the presence of excess H{sub 2} (H{sub 2}:C{sub 6}H{sub 10} ratio = 20-60) is characterized by three regimes: hydrogenation of cyclohexene to cyclohexane at low temperature (< 423 K), an intermediate temperature range in which both hydrogenation and dehydrogenation occur; and a high temperature regime in which the dehydrogenation of cyclohexene dominates (> 573 K). The rate of both reactions demonstrated maxima with temperature, regardless of Pt particle size. For the hydrogenation of cyclohexene, a non-Arrhenius temperature dependence (apparent negative activation energy) was observed. Hydrogenation is structure insensitive at low temperatures, and apparently structure sensitive in the non-Arrhenius regime; the origin of the particle-size dependent reactivity with temperature is attributed to a change in the coverage of reactive hydrogen. Small particles were more active for dehydrogenation and had lower apparent activation energies than large particles. The selectivity can be controlled by changing the particle size, which is attributed to the structure sensitivity of both reactions in the temperature regime where hydrogenation and dehydrogenation are catalyzed simultaneously.

  3. Heterogeneous catalytic oxidative dehydrogenation of ethylbenzene to styrene with carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Badstube, T.; Papp, H. [Leipzig Univ. (Germany). Inst. fuer Technische Chemie; Kustrowski, P.; Dziembaj, R. [Jagiellonian Univ., Crakow (Poland). Faculty of Chemistry

    1998-12-31

    Alkaline promoted active carbon supported iron catalysts are very active in the oxidative dehydrogenation of ethylbenzene to styrene in the presence of carbon dioxide. The best results were obtained at 550 C for a Li-promoted catalyst with a conversion of ethylbenzene of 75% and a selectivity towards styrene of nearly 95%. These results are better than those obtained with industrial catalysts which perform the dehydrogenation process with an excess of water. The main product of the dehydrogenation reaction with CO{sub 2} was styrene, but the following by-products were detected - benzene and toluene. The selectivity towards toluene was always higher than towards benzene. We observed also the formation of carbon monoxide and water, which were produced with a constant molar ratio of about 0.8. The weight of the catalysts increased up to 20% during the reaction due to deposition of carbon. Using a too large excess of CO{sub 2} (CO{sub 2}/EB>10) was harmful for the styrene yield. The most favorable molar ratio of CO{sub 2} to EB was 10:1. No correlation between the molar ratios of reactants and the amount of deposited coke on the surface of catalysts was observed. The highest catalytic activity showed iron loaded D-90 catalysts which were promoted with alkali metals in a molar ratio of 1:10. Iron, nickel and cobalt loaded carbonized PPAN, PC, inorganic supports like Al{sub 2}O{sub 3}, SiO{sub 2}/ZrO{sub 2} or TiO{sub 2} respectively and commercial iron catalysts applied for styrene production did not show comparable catalytic activity in similar conditions. (orig.)

  4. Dehydrogenation of propane in the presence of carbon dioxide over chromium and gallium oxides catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Lapidus, A.L.; Agafonov, Yu.A.; Gaidai, N.A.; Nekrasov, N.V.; Menshova, M.V.; Kunusova, R.M. [Russian Academy of Sciences, Moscow (Russian Federation). N.D. Zelinsky Inst. of Organic Chemistry

    2011-07-01

    Effective chromium and gallium oxides supported catalysts were prepared and tested in longduration experiments for propane dehydrogenation in the presence of CO{sub 2}. The optimal concentrations of active metals were found. It was shown that the activity, selectivity and stability of chromium oxides catalysts were higher than these parameters for gallium ones. Mechanism of propane oxidative dehydrogenation was studied over both catalysts using unstationary and spectroscopic methods. The employment of these methods allowed to establish the differences in process mechanism. It was shown that surface hydroxides took participation in propene formation over Cr-catalysts and hydrides - over Ga-ones. Propane and carbon dioxide participated in the reaction from the adsorbed state over both catalysts but they were differed by the adsorption capacity of the reaction components: CO2 was tied more firmly than C{sub 3}H{sub 6} over both catalysts, CO{sub 2} and C{sub 3}H{sub 6} were tied more strongly with Cr-catalysts than with Ga-ones. It was shown that CO{sub 2} took active participation in reverse watergas shift reaction and in oxidation of catalyst surface over chromium oxides catalysts. The main role of CO{sub 2} in propane dehydrogenation over gallium catalysts consisted in a decrease of coke formation. Step-schemes of propene and cracking products formation were proposed on the basis of literature and obtained data: via the redox mechanism over Cr-catalysts and through a heterolytic dissociation reaction pathway over Ga-ones. (orig.)

  5. Ultrasound promoted catalytic liquid-phase dehydrogenation of isopropanol for Isopropanol-Acetone-Hydrogen chemical heat pump.

    Science.gov (United States)

    Xu, Min; Xin, Fang; Li, Xunfeng; Huai, Xiulan; Liu, Hui

    2015-03-01

    The apparent kinetic of the ultrasound assisted liquid-phase dehydrogenation of isopropanol over Raney nickel catalyst was determined in the temperature range of 346-353 K. Comparison of the effects of ultrasound and mechanical agitation on the isopropanol dehydrogenation was investigated. The ultrasound assisted dehydrogenation rate was significantly improved when relatively high power density was used. Moreover, the Isopropanol-Acetone-Hydrogen chemical heat pump (IAH-CHP) with ultrasound irradiation, in which the endothermic reaction is exposure to ultrasound, was proposed. A mathematical model was established to evaluate its energy performance in term of the coefficient of performance (COP) and the exergy efficiency, into which the apparent kinetic obtained in this work was incorporated. The operating performances between IAH-CHP with ultrasound and mechanical agitation were compared. The results indicated that the superiority of the IAH-CHP system with ultrasound was present even if more than 50% of the power of the ultrasound equipment was lost.

  6. Effect of catalyst structure on oxidative dehydrogenation of ethane and propane on alumina-supported vanadia

    Energy Technology Data Exchange (ETDEWEB)

    Argyle, Morris D.; Chen, Kaidong; Bell, Alexis T.; Iglesia, Enrique

    2001-09-11

    The catalytic properties of Al2O3-supported vanadia with a wide range of VOx surface density (1.4-34.2 V/nm2) and structure were examined for the oxidative dehydrogenation of ethane and propane. UV-visible and Raman spectra showed that vanadia is dispersed predominantly as isolated monovanadate species below {approx}2.3 V/nm2. As surface densities increase, two-dimensional polyvanadates appear (2.3-7.0 V/nm2) along with increasing amounts of V2O5 crystallites at surface densities above 7.0 V/nm2. The rate constant for oxidative dehydrogenation (k1) and its ratio with alkane and alkene combustion (k2/k1 and k3/k1, respectively) were compared for both alkane reactants as a function of vanadia surface density. Propene formation rates (per V-atom) are {approx}8 times higher than ethene formation rates at a given reaction temperature, but the apparent ODH activation energies (E1) are similar for the two reactants and relatively insensitive to vanadia surface density. Ethene and propene formation rates (per V-atom) are strongly influenced by vanadia surface density and reach a maximum value at intermediate surface densities ({approx}8 V/nm2). The ratio of k2/k1 depends weakly on reaction temperature, indicating that activation energies for alkane combustion and ODH reactions are similar. The ratio of k2/k1 is independent of surface density for ethane, but increase slightly with vanadia surface density for propane, suggesting that isolated structures prevalent at low surface densities are slightly more selective for alkane dehydrogenation reactions. The ratio of k3/k1 decreases markedly with increasing reaction temperature for both ethane and propane ODH. Thus, the apparent activation energy for alkene combustion (E3) is much lower than that for alkane dehydrogenation (E1) and the difference between these two activation energies decreases with increasing surface density. The lower alkene selectivities observed at high vanadia surface densities are attributed to an

  7. A STUDY ON MEMBRANE PROCESS WITH γ-ALUMINA MEMBRANE REACTOR FOR ETHYLBENZENE DEHYDROGENATION TO STYRENE

    Institute of Scientific and Technical Information of China (English)

    Chen Qingling; Xu Zhongqiang

    2001-01-01

    The membrane reaction of ethylbenzene(EB) dehydrogenation to styrene(ST) has been studied by using K2O/Fe2O3 industrial catalyst and γ-alumina ceramic membrane developed by our institute. In comparison with the packed bed reactor (that is, plug flow reactor, abbr. PFR) in industrial practice, the yield of styrene was increased by 5%~10% in the membrane reactor. Furthermore, mathematical modeling of membrane reaction has been studied to display the principle of optimal match between the catalytic activity and the membrane permeability.

  8. Ammonia-Borane and Amine-Borane Dehydrogenation Mediated by Complex Metal Hydrides.

    Science.gov (United States)

    Rossin, Andrea; Peruzzini, Maurizio

    2016-08-10

    This review is a comprehensive survey of the last 10 years of research on ammonia-borane and amine-borane dehydrogenation mediated by complex metal hydrides (CMHs), within the broader context of chemical hydrogen storage. The review also collects those cases where CMHs are the catalyst spent form or its resting state. Highlights on the reaction mechanism (strictly dependent on the CMH of choice) and the catalysts efficiency (in terms of equivalents of H2 produced and relative reaction rates) are provided throughout the discussion.

  9. Oxidative Dehydrogenation of Ethane to Ethylene over LiCI/MnOx/PC Catalysts

    Institute of Scientific and Technical Information of China (English)

    葛庆杰; 李文钊; 于春英; 徐恒泳

    2001-01-01

    The caalytic stability of LiCl/MnOx/PC catalyst have been investigated, the deactivation mechanism was discussed. Tne experimental results show that ethane conversion decreases and etihylene selectivotu keeps about 90% as reaction time increases. The main deactivation reasons LiCI/MnOx/PCcatalyst for oxidative dehydrogenation of ethane (ODHE) to ethylene are the transiton of active species Mn2O3 TO MnOspecies and the loss of active component Cl in catalyst. Instead of ethane with FCC tailed-gas, the stability of LiCl/MnOx/PC catalyst has been largely improved.

  10. DNA-based prenatal diagnosis for severe and variant forms of multiple acyl-CoA dehydrogenation deficiency

    DEFF Research Database (Denmark)

    Olsen, Rikke K J; Andresen, Brage S; Christensen, Ernst;

    2005-01-01

    , prenatal diagnosis of MADD has relied mostly on second-trimester biochemical analyses of amniotic fluid or cultured amniocytes. We report here on an alternative DNA-based approach for prenatal diagnosis in pregnancies at risk of MADD. METHODS: We used our knowledge of the mutational status in three...

  11. ETFDH mutations as a major cause of riboflavin-responsive multiple acyl-CoA dehydrogenation deficiency

    DEFF Research Database (Denmark)

    Olsen, Rikke K J; Olpin, Simon E; Andresen, Brage S;

    2007-01-01

    of riboflavin. It is unknown whether these patients have defects in the flavoproteins themselves or defects in the formation of the cofactor, FAD, from riboflavin. We report 15 patients from 11 pedigrees. All the index cases presented with encephalopathy or muscle weakness or a combination of these symptoms...

  12. Clear relationship between ETF/ETFDH genotype and phenotype in patients with multiple acyl-CoA dehydrogenation deficiency

    DEFF Research Database (Denmark)

    Olsen, Rikke K J; Andresen, Brage S; Christensen, Ernst;

    2003-01-01

    activity, we have investigated the molecular genetic basis for disease development in nine patients representing the phenotypic spectrum of MADD. We report the genomic structures of the ETFA, ETFB, and ETFDH genes and the identification and characterization of seven novel and three previously reported...

  13. Dynamic Structure of Mo-O Species in Ag-Mo-P-O Catalyst for Oxidative Dehydrogenation of Propane

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The dynamic structure of Mo-O species in Ag-Mo-P-O catalyst was studied by in situ confocal microprobe laser Raman spectroscopy (LRS) and catalytic test. The results indicate Mo-O species of MoO3 transformed to Mo-O species of AgMoO2PO4 in C3H8/O2/N2 (3/1/4) flow at 773 K. This behavior is closely relative to oxidative dehydrogenation of propane and intrinsic properties of Mo-O species. The Mo-O species of AgMoO2PO4 may be active species for oxidative dehydrogenation of propane.

  14. Iron deficiency

    DEFF Research Database (Denmark)

    Schou, Morten; Bosselmann, Helle; Gaborit, Freja

    2015-01-01

    BACKGROUND: Both iron deficiency (ID) and cardiovascular biomarkers are associated with a poor outcome in heart failure (HF). The relationship between different cardiovascular biomarkers and ID is unknown, and the true prevalence of ID in an outpatient HF clinic is probably overlooked. OBJECTIVES.......043). CONCLUSION: ID is frequent in an outpatient HF clinic. ID is not associated with cardiovascular biomarkers after adjustment for traditional confounders. Inflammation, but not neurohormonal activation is associated with ID in systolic HF. Further studies are needed to understand iron metabolism in elderly HF...

  15. Final Technical Report: Tandem and Bimetallic Catalysts for Oxidative Dehydrogenation of Light Hydrocarbon with Renewable Feedstock

    Energy Technology Data Exchange (ETDEWEB)

    Abu-Omar, Mahdi [Purdue Univ., West Lafayette, IN (United States)

    2017-01-06

    An estimated 490 million metric tons of lignocellulosic biomass is available annually from U.S. agriculture and forestry. With continuing concerns over greenhouse gas emission, the development of efficient catalytic processes for conversion of biomass derived compounds is an important area of research. Since carbohydrates and polyols are rich in oxygen, approximately one oxygen atom per carbon, removal of hydroxyl groups via deoxygenation is needed. The necessary hydrogen required for hydrodeoxygenation (HDO) would either come from reforming biomass itself or from steam reforming of natural gas. Both processes contribute to global CO2 emission. The hope is that eventually renewable sources such as wind and solar for hydrogen production will become more viable and economic in the future. In the meantime, unconventional natural gas production in North America has boomed. As a result, light hydrocarbons present an opportunity when coupled with biomass derived oxygenates to generate valuable products from both streams without co-production of carbon dioxide. This concept is the focus of our current funding period. The objective of the project requires coupling two different types of catalysis, HDO and dehydrogenation. Our hypothesis was formulated around our success in establishing oxorhenium catalysts for polyol HDO reactions and known literature precedence for the use of iridium hydrides in alkane dehydrogenation. To examine our hypothesis we set out to investigate the reaction chemistry of binuclear complexes of oxorhenium and iridium hydride.

  16. Role of Platinum Deposited on TiO2 in Photocatalytic Methanol Oxidation and Dehydrogenation Reactions

    Directory of Open Access Journals (Sweden)

    Luma M. Ahmed

    2014-01-01

    Full Text Available Titania modified nanoparticles have been prepared by the photodeposition method employing platinum particles on the commercially available titanium dioxide (Hombikat UV 100. The properties of the prepared photocatalysts were investigated by means of the Fourier transform infrared spectroscopy (FTIR, X-ray diffraction (XRD, atomic force microscopy (AFM, and UV-visible diffuse spectrophotometry (UV-Vis. XRD was employed to determine the crystallographic phase and particle size of both bare and platinised titanium dioxide. The results indicated that the particle size was decreased with the increasing of platinum loading. AFM analysis showed that one particle consists of about 9 to 11 crystals. UV-vis absorbance analysis showed that the absorption edge shifted to longer wavelength for 0.5% Pt loading compared with bare titanium dioxide. The photocatalytic activity of pure and Pt-loaded TiO2 was investigated employing the photocatalytic oxidation and dehydrogenation of methanol. The results of the photocatalytic activity indicate that the platinized titanium dioxide samples are always more active than the corresponding bare TiO2 for both methanol oxidation and dehydrogenation processes. The loading with various platinum amounts resulted in a significant improvement of the photocatalytic activity of TiO2. This beneficial effect was attributed to an increased separation of the photogenerated electron-hole charge carriers.

  17. Oxidative dehydrogenation of ethane on rare-earth oxide-based catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Buyevskaya, O.; Baerns, M. [Institut fuer Angewandte Chemie Berlin-Adlershof e.V., Berlin (Germany)

    1998-12-31

    Results on the oxidative dehydrogenation of ethane on rare-earth oxide (REO) based catalysts (Na-P-Sm-O, Sm-Sr(Ca)-O, La-Sr-O and Nd-Sr-O) are described. Oxygen adsorption was found to be a key factor which determines the activity of this type of catalysts. Continuous flow experiments in the presence of catalysts which reveal strong oxygen adsorption showed that the reaction mixture is ignited resulting in an enhanced heat generation at the reactor inlet. The heat produced by the oxidative reactions was sufficient under the conditions chosen for the endothermic thermal pyrolysis which takes place preferentially in the gas phase. Ignition of the reaction mixture is an important catalyst function. Contrary to non-catalytic oxidative dehydrogenation, reaction temperatures above 700 C could be achieved without significant external heat input. Ethylene yields of up to 34-45% (S=66-73%) were obtained on REO-based catalysts under non-isothermal conditions (T{sub max}=810-865 C) at contact times in the order of 30 to 40 ms. (orig.)

  18. Low-valent iron(i) amido olefin complexes as promotors for dehydrogenation reactions.

    Science.gov (United States)

    Lichtenberg, Crispin; Viciu, Liliana; Adelhardt, Mario; Sutter, Jörg; Meyer, Karsten; de Bruin, Bas; Grützmacher, Hansjörg

    2015-05-01

    Fe(I) compounds including hydrogenases show remarkable properties and reactivities. Several iron(I) complexes have been established in stoichiometric reactions as model compounds for N2 or CO2 activation. The development of well-defined iron(I) complexes for catalytic transformations remains a challenge. The few examples include cross-coupling reactions, hydrogenations of terminal olefins, and azide functionalizations. Here the syntheses and properties of bimetallic complexes [MFe(I) (trop2 dae)(solv)] (M=Na, solv=3 thf; M=Li, solv=2 Et2 O; trop=5H-dibenzo[a,d]cyclo-hepten-5-yl, dae=(N-CH2 -CH2 -N) with a d(7) Fe low-spin valence-electron configuration are reported. Both compounds promote the dehydrogenation of N,N-dimethylaminoborane, and the former is a precatalyst for the dehydrogenative alcoholysis of silanes. No indications for heterogeneous catalyses were found. High activities and complete conversions were observed particularly with [NaFe(I) (trop2 dae)(thf)3 ].

  19. Effect of Impregnation Sequence on Propane Dehydrogenation Performance of PtSnNa/ZSM-5 Catalyst

    Institute of Scientific and Technical Information of China (English)

    Liu Hui; Zhou Yuming; Zhang Yiwei; Sheng Xiaoli; Zhang Zewu; Zhou Shijiang

    2013-01-01

    The effects of the sequence for impregnation of metal precursors on the performance of PtSnNa/ZSM-5 catalyst for propane dehydrogenation to propene were studied in this paper. Some methods such as XRD, TPDA,BET, H2-TPR, XPS, ICP, TEM and hydrogen chemisorption were used to characterize the catalysts. The structure of ZSM-5 zeolite was not destroyed by the introduction of metal components. Meanwhile the different impregnation sequence of metal precursors could affect the behavior of Sn4+ species entering the ZSM-5 channel, and the interaction between platinum and tin species, as well as the degree for reduction of Pt and Sn components. As a result, the prepared catalysts exhibited different reac-tion activity and selectivity. Compared with the co-impregnation treated catalyst, the catalysts prepared by the sequential impregnation method showed better catalytic activity in propane dehydrogenation, especially the one prepared through im-pregnation with tin precursor at ifrst. Finally, a model for the effect of impregnation sequence on the distribution of Pt and Sn species in PtSnNa/ZSM-5 catalyst was proposed.

  20. Theoretical Study on the Dehydrogenation Reaction of H2S by VS+ (3∑-)

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The dehydrogenation reaction of H2S by the 3∑- ground state of VS+: VS+ + H2S → VS2+ + H2 has been studied by using Density Functional Theory (DFT) at the B3LYP/DZVP level. It is found that the reaction proceeds along two possible pathways (A and B) yielding two isomer dehydrogenation products VS2+-1 (3B2) and VS2+-2 (3A1), respectively. For both pathways,the reaction has a two-step-reaction mechanism that involves the migration of two hydrogen atoms from S2 to V+, respectively. The migration of the second hydrogen via TS3 and that of the first via TS4 are the rate-determining steps for pathways A and B, respectively. The activation energy is 17.4 kcal/mol for pathway A and 22.8 kcal/mol for pathway B relative to the reactants. The calculated reaction heat of 9.9 kcal/mol indicates the endothermicity of pathway A and that of -11.9 kcal/mol suggests the exothermicity of pathway B.

  1. Effect of transition-metal additives on dehydrogenation kinetics of MgH2

    Science.gov (United States)

    Roy, Anindya; Janotti, Anderson; van de Walle, Chris G.

    2013-03-01

    Using first-principles calculations based on hybrid density functional theory we study the (de)hydrogenation process in MgH2, an important solid-state hydrogen storage material. This reaction proceeds through diffusion processes, mediated by native point defects such as vacancies and interstitials. Reducing the formation energy of relevant defects increases their concentrations, resulting in higher diffusion rates and an enhancement in kinetics. We investigate the formation energies of native point defects in MgH2 and determine the position of the Fermi level in the band gap using the charge neutrality condition. The presence of transition-metal (TM) impurities (Ti, Fe, Co and Ni) causes the Fermi level to shift according to the position of the TM acceptor/donor levels in the band gap. This shift can bring down the formation energy of native defects. Our calculations predict that all of the TM additives, in either interstitial or substitutional configurations, may cause such a shift in the Fermi level and thus increase the concentration of the hydrogen vacancies that govern hydrogen diffusion. Our proposed mechanism explains the experimentally observed enhancement in the rate of dehydrogenation of MgH2 upon addition of TM impurities. U.S. Department of Energy (Grant No. DE-FG02-07ER46434), National Energy Research Scientific Computing Center

  2. Formic Acid Dehydrogenation on Au-Based Catalysts at Near-Ambient Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Ojeda, Manuel; Iglesia, Enrique

    2008-11-24

    Formic acid (HCOOH) is a convenient hydrogen carrier in fuel cells designed for portable use. Recent studies have shown that HCOOH decomposition is catalyzed with Ru-based complexes in the aqueous phase at near-ambient temperatures. HCOOH decomposition reactions are used frequently to probe the effects of alloying and cluster size and of geometric and electronic factors in catalysis. These studies have concluded that Pt is the most active metal for HCOOH decomposition, at least as large crystallites and extended surfaces. The identity and oxidation state of surface metal atoms influence the relative rates of dehydrogenation (HCOOH {yields} H{sub 2} + CO{sub 2}) and dehydration (HCOOH {yields} H{sub 2}O + CO) routes, a selectivity requirement for the synthesis of CO-free H{sub 2} streams for low-temperature fuel cells. Group Ib and Group VIII noble metals catalyze dehydrogenation selectively, while base metals and metal oxides catalyze both routes, either directly or indirectly via subsequent water-gas shift (WGS) reactions.

  3. ENHANCEMENT OF EQUILIBRIUMSHIFT IN DEHYDROGENATION REACTIONS USING A NOVEL MEMBRANE REACTOR

    Energy Technology Data Exchange (ETDEWEB)

    Shamsuddin Ilias, Ph.d., P.E.; Franklin G. King, D.Sc.

    2001-02-13

    With the advances in new inorganic materials and processing techniques, there has been renewed interest in exploiting the benefits of membranes in many industrial applications. Inorganic and composite membranes are being considered as potential candidates for use in membrane-reactor configuration for effectively increasing reaction rate, selectivity and yield of equilibrium limited reactions. To investigate the usefulness of a palladium-ceramic composite membrane in a membrane reactor-separator configuration, we investigated the dehydrogenation of cyclohexane by equilibrium shift. A two-dimensional pseudo-homogeneous reactor model was developed to study the dehydrogenation of cyclohexane by equilibrium shift in a tubular membrane reactor. Radial diffusion was considered to account for the concentration gradient in the radial direction due to permeation through the membrane. For a dehydrogenation reaction, the feed stream to the reaction side contained cyclohexane and argon, while the separation side used argon as the sweep gas. Equilibrium conversion for dehydrogenation of cyclohexane is 18.7%. The present study showed that 100% conversion could be achieved by equilibrium shift using Pd-ceramic membrane reactor. For a feed containing cyclohexane and argon of 1.64 x 10{sup -6} and 1.0 x 10{sup -3} mol/s, over 98% conversion could be readily achieved. The dehydrogenation of cyclohexane was also experimentally investigated in a palladium-ceramic membrane reactor. The Pd-ceramic membrane was fabricated by electroless deposition of palladium on ceramic substrate. The performance of Pd-ceramic membrane was compared with a commercially available hydrogen-selective ceramic membrane. From limited experimental data it was observed that by appropriate choice of feed flow rate and sweep gas rate, the conversion of cyclohexane to benzene and hydrogen can increased to 56% at atmospheric pressure and 200 C in a Pd-ceramic membrane reactor. In the commercial ceramic membrane

  4. VLCAD deficiency

    DEFF Research Database (Denmark)

    Boneh, A; Andresen, B S; Gregersen, N

    2006-01-01

    -negative diagnoses of VLCADD in asymptomatic newborn babies. In view of the emerging genotype-phenotype correlation in this disorder, the information derived from mutational analysis can be helpful in designing the appropriate follow-up and therapeutic regime for these patients.......We diagnosed six newborn babies with very long-chain acyl-CoA dehydrogenase deficiency (VLCADD) through newborn screening in three years in Victoria (prevalence rate: 1:31,500). We identified seven known and two new mutations in our patients (2/6 homozygotes; 4/6 compound heterozygotes). Blood...... samples taken at age 48-72 h were diagnostic whereas repeat samples at an older age were normal in 4/6 babies. Urine analysis was normal in 5/5. We conclude that the timing of blood sampling for newborn screening is important and that it is important to perform mutation analysis to avoid false...

  5. A Free-Radical-Promoted Site-Specific Cross-Dehydrogenative-Coupling of N-Heterocycles with Fluorinated Alcohols.

    Science.gov (United States)

    Xu, Zhengbao; Hang, Zhaojia; Chai, Li; Liu, Zhong-Quan

    2016-09-16

    A C-C formation of an electron-rich N-heterocycle with fluorinated alcohol is developed. Through this radical-triggered cross-dehydrogenative coupling strategy, a wide range of useful building blocks such as C3 hydroxyfluoroalkylated indoles and pyrroles can be site-specifically synthesized. Mechanistic studies indicate a single-electron-transfer initiated radical cycle would be involved.

  6. Oxidative Dehydrogenation of n-Butenes to 1,3-Butadiene over Bismuth Molybdate and Ferrite Catalysts: A Review

    KAUST Repository

    Hong, Eunpyo

    2015-11-02

    1,3-Butadiene, an important raw material for a variety of chemical products, can be produced via the oxidative dehydrogenation (ODH) of n-butenes over multicomponent oxide catalysts based on bismuth molybdates and ferrites. In this review, the basic concept, reaction mechanism, and catalysts typically used in an ODH reaction are discussed. © 2015, Springer Science+Business Media New York.

  7. Dehydrogenative Synthesis of Carboxylic Acids from Primary Alcohols and Hydroxide Catalyzed by a Ruthenium N-Heterocyclic Carbene Complex

    DEFF Research Database (Denmark)

    Santilli, Carola; Makarov, Ilya; Fristrup, Peter;

    2016-01-01

    Primary alcohols have been reacted with hydroxide and the ruthenium complex [RuCl2(IiPr)(p-cymene)] to afford carboxylic acids and dihydrogen. The dehydrogenative reaction is performed in toluene, which allows for a simple isolation of the products by precipitation and extraction. The transformat...

  8. Kinetics and Mechanism of the Reaction of Coherently Synchronized Oxidation and Dehydrogenation of Cyclohexane by Hydrogen Peroxide

    Directory of Open Access Journals (Sweden)

    Aghamammadova S.

    2016-01-01

    Based on this experimental researches, the complex reaction, consisting of parallel-sequential oxidation and dehydrogenation reactions, which are coherently synchronized, proceeds during the process of cyclohexane oxidation with biomimetic catalyst. Depending on the reaction parameters it is possible to deliberately adjust the direction of oxidation reaction and reaction rate.

  9. Influence of Ionic Liquids on an Iron(III) Catalyzed Three-Component Coupling/Hydroarylation/Dehydrogenation Tandem Reaction.

    Science.gov (United States)

    Muntzeck, Maren; Wilhelm, René

    2016-06-01

    A three-component oxidative dehydrogenation tandem reaction via the coupling and hydroarylation of benzaldehyde, aniline and phenylacetylene to a quinoline derivate was catalyzed by an iron-containing ionic liquid. The reaction was air mediated and could be performed under neat conditions. The iron(III) of the ionic liquid was the oxidizing species.

  10. Base-Free Production of H-2 by Dehydrogenation of Formic Acid Using An Iridium-bisMETAMORPhos Complex

    NARCIS (Netherlands)

    Oldenhof, S.; de Bruin, B.; Lutz, M.; Siegler, M.A.; Patureau, F.W.; van der Vlugt, J.I.; Reek, J.N.H.

    2013-01-01

    An iridium complex based on a cooperative ligand that functions as an internal base is reported. This complex can rapidly and cleanly dehydrogenate formic acid in absence of external base, a reaction that is required if formic acid is to be exploited as an energy carrier (see scheme).

  11. Facile preparation of β-/γ-MgH₂ nanocomposites under mild conditions and pathways to rapid dehydrogenation.

    Science.gov (United States)

    Xiao, Xuezhang; Liu, Zhe; Saremi-Yarahmadi, Sina; Gregory, Duncan H

    2016-04-21

    A magnesium hydride composite with enhanced hydrogen desorption kinetics can be synthesized via a simple wet chemical route by ball milling MgH2 with LiCl as an additive at room temperature followed by tetrahydrofuran (THF) treatment under an Ar atmosphere. The as-synthesized composite comprises ca. 18 mass% orthorhombic γ-MgH2 and 80 mass% tetragonal β-MgH2 as submicron-sized particles. The β-/γ-MgH2 nanocomposite exhibits a dehydrogenation capacity of 6.6 wt% and starts to release hydrogen at ∼260 °C; ca. 140 °C lower than that of commercial MgH2. The apparent activation energy for dehydrogenation is 115 ± 3 kJ mol(-1), which is ca. 46% lower than that of commercial MgH2. Analysis suggests that the meta-stable γ-MgH2 component either directly dehydrogenates exothermically or first transforms into stable β-MgH2 very close to the dehydrogenation onset. The improved hydrogen release performance can be attributed both to the existence of the MgH2 nanostructure and to the presence of γ-MgH2.

  12. Compositional effects on the hydrogen storage properties of Mg(NH2)2-2LiH-xKH and the activity of KH during dehydrogenation reactions.

    Science.gov (United States)

    Li, Chao; Liu, Yongfeng; Pang, Yuepeng; Gu, Yingjie; Gao, Mingxia; Pan, Hongge

    2014-02-14

    Potassium hydride (KH) was directly added to a Mg(NH2)2-2LiH system to improve the hydrogen storage properties; the corresponding mechanisms were elucidated. The Mg(NH2)2-2LiH-0.08KH composite displays optimized hydrogen-storage properties, reversibly storing approximately 5.2 wt% hydrogen through a two-stage reaction and a dehydrogenation onset at 70 °C. The 0.08KH-added sample fully dehydrogenated at 130 °C begins to absorb hydrogen at 50 °C, and takes up approximately 5.1 wt% of hydrogen at 140 °C. Adding KH significantly enhances the de-/hydrogenation kinetic properties; however, an overly rapid hydrogenation rate enlarges the particle size and raises the dehydrogenation temperature. A cycling evaluation reveals that the KH-added Mg(NH2)2-2LiH system possesses good reversible hydrogen storage abilities, although the operational temperatures for de-/hydrogenation increase during cycling. Detailed mechanistic investigations indicate that adding KH catalytically decreases the activation energy of the first dehydrogenation step and reduces the enthalpy of desorption during the second dehydrogenation step as a reactant, significantly improving the hydrogen storage properties of Mg(NH2)2-2LiH.

  13. THE MATHEMATICAL MODEL DEVELOPMENT OF THE ETHYLBENZENE DEHYDROGENATION PROCESS KINETICS IN A TWO-STAGE ADIABATIC CONTINUOUS REACTOR

    Directory of Open Access Journals (Sweden)

    V. K. Bityukov

    2015-01-01

    Full Text Available The article is devoted to the mathematical modeling of the kinetics of ethyl benzene dehydrogenation in a two-stage adiabatic reactor with a catalytic bed functioning on continuous technology. The analysis of chemical reactions taking place parallel to the main reaction of styrene formation has been carried out on the basis of which a number of assumptions were made proceeding from which a kinetic scheme describing the mechanism of the chemical reactions during the dehydrogenation process was developed. A mathematical model of the dehydrogenation process, describing the dynamics of chemical reactions taking place in each of the two stages of the reactor block at a constant temperature is developed. The estimation of the rate constants of direct and reverse reactions of each component, formation and exhaustion of the reacted mixture was made. The dynamics of the starting material concentration variations (ethyl benzene batch was obtained as well as styrene formation dynamics and all byproducts of dehydrogenation (benzene, toluene, ethylene, carbon, hydrogen, ect.. The calculated the variations of the component composition of the reaction mixture during its passage through the first and second stages of the reactor showed that the proposed mathematical description adequately reproduces the kinetics of the process under investigation. This demonstrates the advantage of the developed model, as well as loyalty to the values found for the rate constants of reactions, which enable the use of models for calculating the kinetics of ethyl benzene dehydrogenation under nonisothermal mode in order to determine the optimal temperature trajectory of the reactor operation. In the future, it will reduce energy and resource consumption, increase the volume of produced styrene and improve the economic indexes of the process.

  14. Vitamin Deficiency Anemia

    Science.gov (United States)

    Vitamin deficiency anemia Overview By Mayo Clinic Staff Vitamin deficiency anemia is a lack of healthy red ... you have lower than normal amounts of certain vitamins. Vitamins linked to vitamin deficiency anemia include folate, ...

  15. Phosphate-modified carbon nanotubes in the oxidative dehydrogenation of isopentanes.

    Science.gov (United States)

    Huang, Rui; Liu, Hong Yang; Zhang, Bing Sen; Sun, Xiao Yan; Liang, Chang Hai; Su, Dang Sheng; Zong, Bao Ning; Rong, Jun Feng

    2014-12-01

    Ketonic/quinonic C=O groups on the surface of a carbon matrix are capable of abstracting hydrogen in C=H bonds from hydrocarbons and enable them to selectively convert into corresponding unsaturated hydrocarbons; this process is the oxidative dehydrogenation (ODH) reaction. However, a variety of inevitable defects or graphene edges and other oxygen-containing groups on the carbon matrix are detrimental to the selective production of alkenes due to their high activity towards overoxidation. Herein, we show that phosphate can not only impede the total oxidation but also cover the selective C=O groups, hence allowing its use as a modulator to defects and oxygen-containing functional groups on the multiwalled carbon nanotubes, regulating the distribution of active sites and related catalytic targets.

  16. Metal oxides modified NiO catalysts for oxidative dehydrogenation of ethane to ethylene

    KAUST Repository

    Zhu, Haibo

    2014-06-01

    The sol-gel method was applied to the synthesis of Zr, Ti, Mo, W, and V modified NiO based catalysts for the ethane oxidative dehydrogenation reaction. The synthesized catalysts were characterized by XRD, N2 adsorption, SEM and TPR techniques. The results showed that the doping metals could be highly dispersed into NiO domains without the formation of large amount of other bulk metal oxide. The modified NiO materials have small particle size, larger surface area, and higher reduction temperature in contrast to pure NiO. The introduction of group IV, V and VI transition metals into NiO decreases the catalytic activity in ethane ODH. However, the ethylene selectivity is enhanced with the highest level for the Ni-W-O and Ni-Ti-O catalysts. As a result, these two catalysts show improved efficiency of ethylene production in the ethane ODH reaction. © 2014 Elsevier B.V. All rights reserved.

  17. Highly selective oxidative dehydrogenation of ethane with supported molten chloride catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Gaertner, C.A.; Veen, A.C. van; Lercher, J.A. [Technische Univ. Muenchen (Germany). Catalysis Research Center

    2011-07-01

    Ethene production is one of the most important transformations in chemical industry, given that C{sub 2}H{sub 4} serves as building block for many mass-market products. Besides conventional thermal processes like steam cracking of ethane, ethane can be produced selectively by catalytic processes. One of the classes of catalysts that have been reported in literature as active and highly selective for the oxidative dehydrogenation of ethane is that of supported molten chloride catalysts, containing an alkali chloride overlayer on a solid support. This work deals with fundamental aspects of the catalytic action in latter class of catalysts. Results from kinetic reaction studies are related to observations in detailed characterization and lead to a comprehensive mechanistic understanding. Of fundamental importance towards mechanistic insights is the oxygen storage capacity of the catalysts that has been determined by transient step experiments. (orig.)

  18. Ethanol dehydrogenation on copper catalysts with ytterbium stabilized tetragonal ZrO2 support

    Science.gov (United States)

    Chuklina, S. G.; Pylinina, A. I.; Podzorova, L. I.; Mikhailina, N. A.; Mikhalenko, I. I.

    2016-12-01

    The physicochemical and catalytic properties of Cu-containing crystalline zirconia, obtained via sol-gel synthesis in the presence of Yb3+ ions and polyvinylpyrrolidone, are studied. DTG/DSC, TEM, XRD and BET methods are used to analyze the crystallization, texture, phase uniformity, surface and porosity of ZrO2 nanopowders. It is shown that increasing the copper content (1, 3, and 5 wt % from ZrO2) raises the dehydrogenation activity in the temperature range of 100-400°C and lowers the activation energy of acetaldehyde formation. It is found that the activity of all Cu/ t-ZrO2 catalysts grows under the effects of the reaction medium, due to the migration and redispersion of copper.

  19. Concept and progress in coupling of dehydrogenation and hydrogenation reactions through catalysts

    Indian Academy of Sciences (India)

    C V Pramod; C Raghavendra; K Hari Prasad Reddy; G V Ramesh Babu; K S Rama Rao; B David Raju

    2014-03-01

    This review focuses on the importance of coupling of catalytic reactions which involves dehydrogenation and hydrogenation simultaneously and the study of catalytic materials that are designed, adopted and/or modified for these reactions. The special features of these reactions are minimization of H2 utilization and reduction in production cost. Structural and textural properties also play a decisive role in this kind of coupled reactions. This particular review although not comprehensive discusses the significant progress made in the area of coupled reactions and also helps future researchers or engineers to find out the improvements required in areas such as advancements in catalytic material preparation, design of the new reactors and the application of new technologies.

  20. Influence of promoters and oxidants on propane dehydrogenation over chromium-oxide catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Lapidus, A.L.; Agafonov, Yu.A.; Shaporeva, N.Yu.; Trushin, D.V.; Gaidai, N.A.; Nekrasov, N.V. [Russian Academy of Sciences, Moscow (Russian Federation). N.D. Zelinsky Inst. of Organic Chemistry

    2010-12-30

    Possibilities for increasing the efficiency of supported on SiO{sub 2} chromium-oxide catalysts in propane oxidative dehydrogenation in CO{sub 2} presence are investigated: the introduction of Li, Na, K, Ca in catalysts and the addition of O{sub 2} in the reaction mixture. It was been found that the positive role of K - the increase of the selectivity to propene and stability of catalysts at long-duration tests - appeared at the relation of Cr:K=20. It was shown that the presence of little amount of O{sub 2} (2%) in the reaction mixtures of propane and carbon dioxide resulted in the increase of propene yield and catalyst stability. (orig.)

  1. Green synthesis of Ni-Nb oxide catalysts for low-temperature oxidative dehydrogenation of ethane

    KAUST Repository

    Zhu, Haibo

    2015-03-05

    The straightforward solid-state grinding of a mixture of Ni nitrate and Nb oxalate crystals led to, after mild calcination (T<400°C), nanostructured Ni-Nb oxide composites. These new materials efficiently catalyzed the oxidative dehydrogenation (ODH) of ethane to ethylene at a relatively low temperature (T<300°C). These catalysts appear to be much more stable than the corresponding composites prepared by other chemical methods; more than 90% of their original intrinsic activity was retained after 50h with time on-stream. Furthermore, the stability was much less affected by the Nb content than in composites prepared by classical "wet" syntheses. These materials, obtained in a solvent-free way, are thus promising green and sustainable alternatives to the current Ni-Nb candidates for the low-temperature ODH of ethane.

  2. Compensation Effect in the Hydrogenation/Dehydrogenation Kinetics of Metal Hydrides

    DEFF Research Database (Denmark)

    Andreasen, A.; Vegge, T.; Pedersen, Allan Schrøder

    2005-01-01

    The possible existence of a compensation effect, i.e. concurrent changes in activation energy and prefactor, is investigated for the hydrogenation and dehydrogenation kinetics of metal hydrides, by analyzing a series of reported kinetic studies on Mg and LaNi5 based hydrides. For these systems, we...... find a clear linear relation between apparent prefactors and apparent activation energies, as obtained from an Arrhenius analysis, indicating the existence of a compensation effect. Large changes in apparent activation energies in the case of Mg based hydrides are rationalized in terms of a dependency...... analysis rather than a physical phenomenon. In the case of LaNi5 based hydrides, observed scatter in reported apparent activation energies is less pronounced supporting the general experience that LaNi5 is less sensitive toward surface contamination....

  3. Dehydrogenation in lithium borohydride/conventional metal hydride composite based on a mutual catalysis

    DEFF Research Database (Denmark)

    Yu, X.B.; Shi, Qing; Vegge, Tejs;

    2009-01-01

    The dehydrogenation of LiBH4 ball-milled with hydrogenated 40Ti–15Mn–15Cr–30V alloy was investigated. It was found that there is a mutual catalysis between the two hydrides, lowering the temperature of hydrogen release from both hydrides. In the case of 1h milled LiBH4/40Ti–15Mn–15Cr–30V...... with a mass ratio of 1:4, the peak temperatures of 40Ti–15Mn–15Cr–30V and LiBH4 were decreased to 195 and 390°C, respectively, which are 77 and 50°C lower than the respective hydride on its own....

  4. Kinetics modeling of ethylbenzene dehydrogenation to styrene over a mesoporous alumina supported iron catalyst

    KAUST Repository

    Hossain, Mohammad M.

    2012-10-01

    The kinetics of ethylbenzene (EB) dehydrogenation over a FeO x-meso-Al 2O 3 catalyst is studied. The models were developed based on physicochemical characterization and a CREC fluidized Riser Simulator data. N 2 adsorption shows that the synthesized FeO x-meso-Al 2O 3 catalyst is mesoporous with pore size between 9 and 35nm. TPR profile indicates that iron on meso-Al 2O 3 forms easily reducible nanostructured crystals which is confirmed by TEM image. NH 3- and CO-TPD analysis, respectively reveals the availability of both acidic and basic sites. The dehydrogenation of ethylbenzene on FeO x-meso-Al 2O 3 catalyst mainly gives styrene (∼99%) while a small amount of benzene, toluene and coke are also detected. Based on the experimental observations two Langmuir-Hinshelwood type kinetics models are formulated. The possible catalyst deactivation is expressed as function of EB conversion. Parameters are estimated by fitting of the experimental data implemented in MATLAB. Results show that one type site Langmuir-Hinshelwood model appropriately describes the experimental data, with adequate statistical fitting indicators and also satisfied the physical constraints. The activation energy for the formation of styrene (80kJ/mol) found to be significantly lower than that of the undesired products benzene (144kJ/mol) and toluene (164kJ/mol). The estimated heat of adsorptions of EB and ST are found to be 55kJ/mol and 19kJ/mol, respectively. © 2012 Elsevier B.V.

  5. Ethylbenzene dehydrogenation over binary FeOx–MeOy/Mg(Al)O catalysts derived from hydrotalcites

    KAUST Repository

    Balasamy, Rabindran J.

    2010-12-20

    A series of FeOx-MeOy/Mg(Al)O catalysts were prepared from hydrotalcite-like compounds as precursors and were tested in the ethylbenzene dehydrogenation to styrene in He atmosphere at 550 °C. The hydrotalcite-like precursors of the metal compositions of Mg3Fe 0.25Me0.25Al0.5 (Me = Cu, Zn, Cr, Mn, Fe, Co and Ni) were coprecipitated from the nitrates of metal components and calcined to mixed oxides at 550 °C. After the calcination, the mixed oxides showed high surface area of 150-200 m2 gcat -1, and were mainly composed of (MgMe)(Fe3+Al)O periclase in the bulk, whereas the surface was enriched by (MgMe)(Fe3+Al)2O 4 pinel. Among the Me species tested, Co2+ was the most effective, followed by Ni2+. Co2+ addition increased the activity of original FeOx/Mg(Al)O catalyst, whereas Ni2+ increased the activity at the beginning of reaction, but deactivated the catalyst during the reaction. The other metals formed isolated MeOx species in the catalyst, resulting in a decrease in the activity compared to the original FeOx/Mg(Al)O catalyst. The active Fe species exists as metastable Fe3+ on the FeOx/Mg(Al)O catalyst. By the addition of Co2+, the reduction-oxidation between Fe3+ and Fe2+ was facilitated and, moreover, the active Fe3+ species was stabilized. It is likely that the dehydrogenation proceeds on the active Fe3+ species via its reduction-oxidation assisted by Co 2+. © 2010 Elsevier B.V.

  6. A study of the isobutane dehydrogenation in a porous membrane catalytic reactor: design, use and modelling

    Energy Technology Data Exchange (ETDEWEB)

    Casanave, D.

    1996-01-26

    The aim of this study was to set up and model a catalytic fixed-bed membrane reactor for the isobutane dehydrogenation. The catalyst, developed at Catalysis Research Institute (IRC), was a silicalite-supported Pt-based catalyst. Their catalytic performances (activity, selectivity, stability) where found better adapted to the membrane reactor, when compared with commercial Pt or Cr based catalysts. The kinetic study of the reaction has been performed in a differential reactor and led to the determination of a kinetic law, suitable when the catalyst is used near thermodynamic equilibrium. The mass transfer mechanisms were determined in meso-porous and microporous membranes through both permeability and gas mixtures (iC{sub 4}/H{sub 2}/N{sub 2}) separation measurements. For the meso-porous {gamma}-alumina, the mass transfer is ensured by a Knudsen diffusion mechanism which can compete with surface diffusion for condensable gas like isobutane. The resulting permselectivity H{sub 2}/iC4 of this membrane is low ({approx} 4). For the microporous zeolite membrane, molecular sieving occurs due to steric hindrance, leading to higher permselectivity {approx}14. Catalyst/membrane associations were compared in terms of isobutane dehydrogenation performances, for both types of membranes (meso-porous and microporous) and for two different reactor configurations (co-current and counter-current sweep gas flow). The best experimental results were obtained with the zeolite membrane, when sweeping the outer compartment in a co-current flow. The equilibrium displacement observed with the {gamma}-alumina membrane was lower and mainly due to a dilution effect of the reaction mixture by the sweep gas. A mathematical model was developed, which correctly describes all the experimental results obtained with the zeolite membrane, when the co-current mode is used. (Abstract Truncated)

  7. Kinetics on NiZn Bimetallic Catalysts for Hydrogen Evolution via Selective Dehydrogenation of Methylcyclohexane to Toluene

    KAUST Repository

    Shaikh Ali, Anaam

    2017-01-18

    Liquid organic chemical hydrides are effective hydrogen storage media for easy and safe transport. The chemical couple of methylcyclohexane (MCH) and toluene (TOL) has been considered one of the feasible cycles for a hydrogen carrier, but the selective dehydrogenation of MCH to TOL has been reported using only Pt-based noble metal catalysts. This study reports MCH dehydrogenation to TOL using supported NiZn as a selective, non-noble-metal catalyst. A combined experimental and computational study was conducted to provide insight into the site requirements and reaction mechanism for MCH dehydrogenation to TOL, which were compared with those for cyclohexane (CH) dehydrogenation to benzene (BZ). The kinetic measurements carried out at 300-360°C showed an almost zero order with respect to MCH pressure in the high-pressure region (≥10 kPa) and nearly a positive half order with respective to H pressure (≤40 kPa). These kinetic data for the dehydrogenation reaction paradoxically indicate that hydrogenation of a strongly chemisorbed intermediate originating from TOL is the rate-determining step. Density functional theory (DFT) calculation confirms that the dehydrogenated TOL species at the aliphatic (methyl) position group (CHCH) were strongly adsorbed on the surface, which must be hydrogenated to desorb as TOL. This hydrogen-assisted desorption mechanism explains the essential role of excess H present in the feed in maintaining the activity of the metallic surface for hydrogenation. The rate of the CH to BZ reaction was less sensitive to H pressure than that of MCH to TOL, which can be explained by the absence of a methyl group in the structure, which in turn reduces the binding energy of the adsorbed species. DFT suggests that the improved TOL selectivity by adding Zn to Ni was due to Zn atoms preferentially occupying low-coordination sites on the surface (the corner and edge sites), which are likely the unselective sites responsible for the C-C dissociation of the

  8. Improved Dehydrogenation Properties of 2LiNH2-MgH2 by Doping with Li3AlH6

    Directory of Open Access Journals (Sweden)

    Shujun Qiu

    2017-01-01

    Full Text Available Doping with additives in a Li-Mg-N-H system has been regarded as one of the most effective methods of improving hydrogen storage properties. In this paper, we prepared Li3AlH6 and evaluated its effect on the dehydrogenation properties of 2LiNH2-MgH2. Our studies show that doping with Li3AlH6 could effectively lower the dehydrogenation temperatures and increase the hydrogen content of 2LiNH2-MgH2. For example, 2LiNH2-MgH2-0.1Li3AlH6 can desorb 6.43 wt % of hydrogen upon heating to 300 °C, with the onset dehydrogenation temperature at 78 °C. Isothermal dehydrogenation testing indicated that 2LiNH2-MgH2-0.1Li3AlH6 had superior dehydrogenation kinetics at low temperature. Moreover, the release of byproduct NH3 was successfully suppressed. Measurement of the thermal diffusivity suggests that the enhanced dehydrogenation properties may be ascribed to the fact that doping with Li3AlH6 could improve the heat transfer for solid–solid reaction.

  9. Carnitine Deficiency and Pregnancy

    OpenAIRE

    Anouk de Bruyn; Yves Jacquemyn; Kristof Kinget; François Eyskens

    2015-01-01

    We present two cases of carnitine deficiency in pregnancy. In our first case, systematic screening revealed L-carnitine deficiency in the first born of an asymptomatic mother. In the course of her second pregnancy, maternal carnitine levels showed a deficiency as well. In a second case, a mother known with carnitine deficiency under supplementation was followed throughout her pregnancy. Both pregnancies had an uneventful outcome. Because carnitine deficiency can have serious complications, su...

  10. Synthesis and applications of mesoporous Cu-Zn-Al2O3 catalyst for dehydrogenation of 2-butanol

    Institute of Scientific and Technical Information of China (English)

    Deren Fang; Wanzhong Ren; Zhongmin Liu; Xiufeng Xu; Lei Xu; Hongying L(u); Weiping Liao; Huimin Zhang

    2009-01-01

    A series of mesoporous Cu-Zn-Al2O3 materials have been synthesized at ambient temperature and their structure was characterized by XRD, N2 physical adsorption and TPR techniques. Their catalytic applications for the dehydrogenation of 2-butanol to methyl ethyl ketone (MEK) were evaluated in a fixed-bed flow reactor at atmospheric pressure. It is demonstrated from the XRD patterns that both the as-synthesized samples and calcined samples have the typical XRD patterns of meso-structured materials and the results of N2O chemical adsorption showed that Cu was embedded in the framework of the mesoporous materials and homogeneously dispersed in the mesoporous Cu-Zn-Al2O3 materials. The catalytic activity of 2-hntanol dehydrogenation was varied in the order of CZA(10)

  11. Direct and Efficient Dehydrogenation of Tetrahydroquinolines and Primary Amines Using Corona Discharge Generated on Ambient Hydrophobic Paper Substrate

    Science.gov (United States)

    Davis, Kathryn M.; Badu-Tawiah, Abraham K.

    2016-10-01

    The exposure of an aqueous-based liquid drop containing amines and graphite particles to plasma generated by a corona discharge results in heterogeneous aerobic dehydrogenation reactions. This green oxidation reaction occurring in ambient air afforded the corresponding quinolines and nitriles from tetrahydroquinolines and primary amines, respectively, at >96% yields in less than 2 min of reaction time. The accelerated dehydrogenation reactions occurred on the surface of a low energy hydrophobic paper, which served both as container for holding the reacting liquid drop and as a medium for achieving paper spray ionization of reaction products for subsequent characterization by ambient mass spectrometry. Control experiments indicate superoxide anions (O2 •-) are the main reactive species; the presence of graphite particles introduced heterogeneous surface effects, and enabled the efficient sampling of the plasma into the grounded analyte droplet solution.

  12. Facile synthesis of TiN decorated graphene and its enhanced catalytic effects on dehydrogenation performance of magnesium hydride

    Science.gov (United States)

    Wang, Ying; Li, Li; An, Cuihua; Wang, Yijing; Chen, Chengcheng; Jiao, Lifang; Yuan, Huatang

    2014-05-01

    TiN@rGO nanohybrids were successfully synthesized by a simple ``urea glass'' technique. Experimental results demonstrated that TiN nanocrystals, with an average particle size of 20 nm, were uniformly anchored onto highly reduced graphene nanosheets. The as-synthesized TiN@rGO nanohybrids showed a porous planar-like structure, which had a large surface area of 177 m2 g-1. More importantly, the as-prepared TiN@rGO hybrids showed enhanced catalytic effects on the dehydrogenation of MgH2. The dehydrogenation thermodynamics and kinetics of the MgH2-TiN@rGO composites were systematically investigated and some significant improvements were confirmed. It was found that the 10 wt% TiN@rGO doped MgH2 sample started to release hydrogen at about 167 °C, and roughly 6.0 wt% hydrogen was released within 18 min when isothermally heated to 300 °C. In contrast, the onset dehydrogenation temperature of the pure MgH2 sample was about 307 °C, and only 3.5 wt% hydrogen was released even after 120 min of heating under identical conditions. In addition, the catalytic mechanism of TiN@rGO on the dehydrogenation of MgH2 was discussed using the Johnson-Mehl-Avrami (JMA) model and X-ray diffraction equipment.TiN@rGO nanohybrids were successfully synthesized by a simple ``urea glass'' technique. Experimental results demonstrated that TiN nanocrystals, with an average particle size of 20 nm, were uniformly anchored onto highly reduced graphene nanosheets. The as-synthesized TiN@rGO nanohybrids showed a porous planar-like structure, which had a large surface area of 177 m2 g-1. More importantly, the as-prepared TiN@rGO hybrids showed enhanced catalytic effects on the dehydrogenation of MgH2. The dehydrogenation thermodynamics and kinetics of the MgH2-TiN@rGO composites were systematically investigated and some significant improvements were confirmed. It was found that the 10 wt% TiN@rGO doped MgH2 sample started to release hydrogen at about 167 °C, and roughly 6.0 wt% hydrogen was released

  13. Catalytic mechanism of the dehydrogenation of ethylbenzene over Fe–Co/Mg(Al)O derived from hydrotalcites

    KAUST Repository

    Tope, Balkrishna B.

    2011-11-01

    Catalytic mechanism of ethylbenzene dehydrogenation over Fe-Co/Mg(Al)O derived from hydrotalcites has been studied based on the XAFS and XPS catalyst characterization and the FTIR measurements of adsorbed species. Fe-Co/Mg(Al)O showed synergy, whereas Fe-Ni/Mg(Al)O showed no synergy, in the dehydrogenation of ethylbenzene. Ni species were stably incorporated as Ni2+ in the regular sites in periclase and spinel structure in the Fe-Ni/Mg(Al)O. Contrarily, Co species exists as a mixture of Co3+/Co2+ in the Fe-Co/Mg(Al)O and was partially isolated from the regular sites in the structures with increasing the Co content. Co addition enhanced Lewis acidity of Fe3+ active sites by forming Fe3+-O-Co 3+/2+(1/1) bond, resulting in an increase in the activity. FTIR of ethylbenzene adsorbed on the Fe-Co/Mg(Al)O clearly showed formations of C-O bond and π-adsorbed aromatic ring. This suggests that ethylbenzene was strongly adsorbed on the Fe3+ acid sites via π-bonding and the dehydrogenation was initiated by α-H+ abstraction from ethyl group on Mg2+-O2- basic sites, followed by C-O-Mg bond formation. The α-H+ abstraction by O2-(-Mg 2+) was likely followed by β-H abstraction, leading to the formations of styrene and H2. Such catalytic mechanism by the Fe 3+ acid-O2-(-Mg2+) base couple and the Fe 3+/Fe2+ reduction-oxidation cycle was further assisted by Co3+/Co2+, leading to a good catalytic activity for the dehydrogenation of ethylbenzene. © 2011 Elsevier B.V. All rights reserved.

  14. Sequential decarboxylative azide–alkyne cycloaddition and dehydrogenative coupling reactions: one-pot synthesis of polycyclic fused triazoles

    Directory of Open Access Journals (Sweden)

    Kuppusamy Bharathimohan

    2014-12-01

    Full Text Available Herein, we describe a one-pot protocol for the synthesis of a novel series of polycyclic triazole derivatives. Transition metal-catalyzed decarboxylative CuAAC and dehydrogenative cross coupling reactions are combined in a single flask and achieved good yields of the respective triazoles (up to 97% yield. This methodology is more convenient to produce the complex polycyclic molecules in a simple way.

  15. Study of the performance of vanadium based catalysts prepared by grafting in the oxidative dehydrogenation of propane

    Energy Technology Data Exchange (ETDEWEB)

    Santacesaria, E.; Carotenuto, G.; Tesser, R.; Di Serio, M. [Naples Univ. (Italy). Dept. of Chemistry

    2011-07-01

    The oxidative dehydrogenation (ODH) of propane has been investigated by using many different vanadia based catalysts, prepared by grafting technique and containing variable amounts of active phase supported on SiO{sub 2} previously coated, by grafting in three different steps, with multilayer of TiO{sub 2}. A depth catalytic screening, conducted in a temperature range of 400-600 C, at atmospheric pressure and in a range of residence time W/F=0.08-0.33 ghmol{sub -1}, has shown that the vanadium oxide catalysts on TiO{sub 2}-SiO{sub 2} support, prepared by grafting have good performances in the ODH of propane. In particular, a preliminary study has demonstrated that higher selectivities can be obtained employing catalysts having a well dispersed active phase that can be achieved with a V{sub 2}O{sub 5} content lower than 10%{sub w}t. It is well known that, in the case of redox catalysts, an increase of the selectivity can be achieved not only by using an adequate catalytic system but also via engineering routes like decoupling catalytic steps of reduction and re-oxidation. In fact it has been observed that by operating in dehydrogenating mode, on the same catalysts, a higher selectivity is obtained although the catalyst is poisoned by the formation of coke on the surface. As consequence of the results obtained in dehydrogenation, in this work has been explored the possibility to feed low amounts of oxygen, below the stoichiometric level with the aim to keep clean the surface from coke but maintaining high the selectivity, because, dehydrogenation reaction prevails. In this work, the behavior of catalysts containing different amounts of V2O5 has been studied in the propane-propene reaction by using different ratios C{sub 3}H{sub 8}/O{sub 2} included in the range 0-2. (orig.)

  16. OXIDATIVE DEHYDROGENATION OF PROPANE BY RARE EARTH PHOSPHATES SUPPORTED ON AL-PILC

    Directory of Open Access Journals (Sweden)

    Carolina De Los Santos

    2012-12-01

    Full Text Available Catalytic activity in propane oxidative dehydrogenation of rare earth phosphates LnPO4 (where Ln = La, Ce, Pr, Nd, Sm and of the same supported by an aluminum pillared clay, of high specific surface area, is presented. The solids were characterized by TGA, XRD, nitrogen adsorption and immediate analysis after reaction in order to determine eventual carbon formation. Catalytic assays were performed at temperatures in the range 400oC-600oC, the reaction mixture was C3H8/O2/Ar = 10/10/80. All the catalysts were active. The reaction products were H2, CO, CO2, CH4, C2H4 and C3H6 and there were no organic oxygenated compounds detected. Although all the investigated systems were active, the Al-PILC supported catalysts presented a higher activity than the bulk materials. In this context, the samarium supported catalyst showed a propene yield increase from 4% to 10% compared with bulk samarium phosphate at 600°C. This effect was attributed to the increase in the specific surface area.

  17. Molecular lifting, twisting, and curling during metal-assisted polycyclic hydrocarbon dehydrogenation

    Science.gov (United States)

    Curcio, Davide; Omiciuolo, Luca; Pozzo, Monica; Lacovig, Paolo; Lizzit, Silvano; Jabeen, Naila; Petaccia, Luca; Alfe, Dario; Baraldi, Alessandro

    Through a combined experimental and theoretical approach, we show that coronene molecules adsorbed on Ir(111) undergo major changes in conformation during the dissociation process, which brings the molecules from a flat configuration to graphene, through a series of exotic configurations. The complex reaction path involves the tilting upwards of the molecules, which subsequently experience a rotation with respect to the surface. During the lifting, the C-C strain is initially relieved, while as the dehydrogenation proceeds, the molecules experience a progressive increase in the average interatomic distance, and gradually settle to form peculiar dome shaped nanographenes. This reaction mechanism can provide new insight into the surface assisted break-up mechanism of PAHs, which has been demonstrated to be an effective strategy for the synthesis of low dimensional carbon-based materials. Beside the peculiarity of the reaction pathway, using these processes we envisage the unique possibility of creating new structures with different functionalities by encapsulating single atoms below the carbon dome.

  18. Effect of surface phosphorus on the oxidative dehydrogenation of ethane: A first-principles investigation

    Science.gov (United States)

    Maiti, Amitesh; Govind, Niranjan; Kung, Paul; King-Smith, Dominic; Miller, James E.; Zhang, Conrad; Whitwell, George

    2002-11-01

    Oxidative dehydrogenation (ODH) of small-chain alkanes has the potential to displace thermal cracking as the preferred method of light olefin production. Many heterogeneous catalysts for the ODH reaction have been discussed in the literature, including oxides, vanadates, and phosphates of rare earth and transition metals. Our experiments and the literature indicate that for most of these catalysts, including silica gel and alumina, a phosphorus-enriched surface enhances the ODH yield of ethane to ethylene. To understand the role of P, the ODH reactions were simulated on a silica surface, with and without P, using the density functional theory code DMol3 in a periodic supercell. Optimized structures for all intermediates as well as transition states were obtained for full catalytic cycles. The simulations reveal that activation barriers for the rate-limiting steps are lowered by ˜10 kcal/mol in the presence of P. The decrease results from a transition state in which the P atom remains quasi-5-valent and fourfold coordinated.

  19. Dehydrogenative silane coupling on silicon surfaces via early transition metal catalysis.

    Science.gov (United States)

    Li, Yun-Hui; Buriak, Jillian M

    2006-02-01

    Derivatization of silicon surfaces is an area of intense interest due to the centrality of silicon in the microelectronics industry and because of potential promise for a myriad of other applications. In this paper, we investigate the feasibility of Si-Si bond formation directly on the surface to contrast with the more widely studied Si-C and Si-O bond forming reactions. Functionalization of hydride-terminated silicon surfaces with silanes is carried out via early transition metal mediated dehydrogenative silane coupling reactions. Zirconocene and titanocene catalyst systems were evaluated for heterocoupling of a molecular silane, RSiH3, with a surface Si-H group on Si(s). The zirconocene catalysts proved to be much more reactive than the titanium system, and so the former was examined exclusively. The silanes, aromatic or aliphatic, are bonded to the silicon surface through direct Si-Si bonds, although the level of incorporation of the trihydroarylsilanes was substantially higher than that of the aliphatic silanes. The reaction proceeds on nanocrystalline hydride-terminated porous silicon surfaces, as well as flat Si(100)-H(x) and Si(111)-H interfaces. The reactions were studied by a variety of techniques, including FTIR, SIMS, and XPS.

  20. Synergistic effect between Sn and K promoters on supported platinum catalyst for isobutane dehydrogenation

    Institute of Scientific and Technical Information of China (English)

    Yiwei Zhang; Yuming Zhou; Lihui Wan; Mengwei Xue; Yongzheng Duan; Xuan Liu

    2011-01-01

    Catalytic dehydrogenation of isobutane has recently received considerable attention because of the increasing demand for isobutene.In this study,the synergistic effect between Sn and K on PtSnK/γ-Al2O3 catalysts has been investigated by changing the content of Sn.It was found that with the presence of potassium,suitable addition of Sn could not only increase the metal dispersion,but also reduce the catalyst acidity.In these cases,the synergistic effect could also strengthen the interactions between the metal and support,which resulted in an increase in both catalytic activity and stability.In our experiments,Pt-0.6SnK/Al catalyst exhibited the lowest deactivation rate (12.4%) and showed a selectivity to isobutene higher than 94% at the isobutane conversion of about 45.3% after running the reaction for 6 h.However,with the excessive loading of Sn,surface property of active sites and the interactions between metal and support were changed.As a result,the initial optimal ratio between the metallic function and acid function would be destroyed,which was disadvantageous to the reaction.

  1. Defective fullerenes as catalyst for dehydrogenation from NaAlH4 clusters

    Science.gov (United States)

    Agnihotri, Deepak; Meenakshi, Sharma, Hitesh

    2015-06-01

    In the present work we have shown that C60 with defect can act as an effective catalyst for dehydrogenation from NaAlH4 clusters. The investigations have been performed using density functional theory calculations. The NaAlH4 interact weakly with the C60 with vacancy defect with binding energy of 0.26eV. The hydrogen release energy shows sharp decrease in magnitude from 3.82eV in NaAlH4 to 1.97 eV in C59NaAlH4 and 1.63eV in C58BNaAlH4. The results may be explained on the basis of change in the net charge at Na and AlH4 resulting in weaker ionic interaction due to interaction between NaAlH4 cluster and C60 with defect. The present results may provide valued insights of experimental work for exploring the catalytic potential of C60 with various defects.

  2. Compensation effect in the hydrogenation/dehydrogenation kinetics of metal hydrides.

    Science.gov (United States)

    Andreasen, Anders; Vegge, Tejs; Pedersen, Allan S

    2005-03-03

    The possible existence of a compensation effect, i.e. concurrent changes in activation energy and prefactor, is investigated for the hydrogenation and dehydrogenation kinetics of metal hydrides, by analyzing a series of reported kinetic studies on Mg and LaNi(5) based hydrides. For these systems, we find a clear linear relation between apparent prefactors and apparent activation energies, as obtained from an Arrhenius analysis, indicating the existence of a compensation effect. Large changes in apparent activation energies in the case of Mg based hydrides are rationalized in terms of a dependency of observed apparent activation energy on the degree of surface oxidation, i.e., a physical effect. On the other hand, we find the large concurrent changes in apparent prefactors to be a direct result of the Arrhenius analysis. Thus, we find the observed compensation effect to be an artifact of the data analysis rather than a physical phenomenon. In the case of LaNi(5) based hydrides, observed scatter in reported apparent activation energies is less pronounced supporting the general experience that LaNi(5) is less sensitive toward surface contamination.

  3. Study of the hydrogenation/dehydrogenation process in the Mg–Ni–C–Al system

    Energy Technology Data Exchange (ETDEWEB)

    Palumbo, O. [CNR-ISC, U.O.S. La Sapienza, Piazzale A. Moro 5, 00185 Roma (Italy); Research Center Hydro-Eco, Sapienza University of Rome, Via A. Scarpa 14, 00161 Roma (Italy); Trequattrini, F. [Physics Department, Sapienza University of Rome, Piazzale A. Moro 5, 00185 Roma (Italy); Vitucci, F.M. [CNR-ISC, U.O.S. La Sapienza, Piazzale A. Moro 5, 00185 Roma (Italy); Bianchin, A. [MBN Nanomaterialia S.p.A., Via G. Bortolan 42, 31040 Vascon di Carbonera-TV (Italy); Paolone, A., E-mail: annalisa.paolone@roma1.infn.it [CNR-ISC, U.O.S. La Sapienza, Piazzale A. Moro 5, 00185 Roma (Italy); Research Center Hydro-Eco, Sapienza University of Rome, Via A. Scarpa 14, 00161 Roma (Italy)

    2015-10-05

    Highlights: • A Mg–Ni–C–Al mixture synthesized for application as pellets in a tank is studied. • It is the combination of a hydrogen storing composite with a binding phase. • The storage properties are studied by PCI curves, TGA–DSC and XRD. • The hydrogen absorbtion/desorption occurs in two steps. • The thermodynamics of the first more massive step is improved compared to MgH{sub 2}. - Abstract: In this work we present a detailed study of the hydrogenation and dehydrogenation processes of a nanostructured Mg–Ni–C–Al mixture. The sample has been characterized by means of X-ray diffraction, concomitant thermogravimetric and differential scanning calorimetry measurements and pressure-composition isothermal analyses. The hydrogenation takes place in two steps and is compatible with the formation of MgH{sub 2} and Mg{sub 2}NiH{sub 4}. The enthalpy and the activation energy measured for the main hydrogen desorption are lower than those ones reported for magnesium hydride.

  4. Folate-deficiency anemia

    Science.gov (United States)

    ... medlineplus.gov/ency/article/000551.htm Folate-deficiency anemia To use the sharing features on this page, please enable JavaScript. Folate-deficiency anemia is a decrease in red blood cells (anemia) ...

  5. Anemia - B12 deficiency

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/000574.htm Vitamin B12 deficiency anemia To use the sharing features on ... tissues. There are many types of anemia. Vitamin B12 deficiency anemia is a low red blood cell ...

  6. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... or an inability to absorb enough iron from food. Overview Iron-deficiency anemia is a common type ... of the condition. Treatments may include dietary changes, medicines, and surgery. Severe iron-deficiency anemia may require ...

  7. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... the NHLBI on Twitter. What Is Iron-Deficiency Anemia? Español Iron-deficiency anemia is a common, easily ... Featured Video Living With and Managing Iron-Deficiency Anemia 05/18/2011 This video—presented by the ...

  8. Iron-Deficiency Anemia

    Science.gov (United States)

    ... the NHLBI on Twitter. What Is Iron-Deficiency Anemia? Español Iron-deficiency anemia is a common, easily ... Featured Video Living With and Managing Iron-Deficiency Anemia 05/18/2011 This video—presented by the ...

  9. Iron-Deficiency Anemia

    Science.gov (United States)

    ... page from the NHLBI on Twitter. What Is Iron-Deficiency Anemia? Español Iron-deficiency anemia is a common, ... Content: NEXT >> Featured Video Living With and Managing Iron-Deficiency Anemia 05/18/2011 This video—presented by ...

  10. Carnitine Deficiency and Pregnancy

    Directory of Open Access Journals (Sweden)

    Anouk de Bruyn

    2015-01-01

    Full Text Available We present two cases of carnitine deficiency in pregnancy. In our first case, systematic screening revealed L-carnitine deficiency in the first born of an asymptomatic mother. In the course of her second pregnancy, maternal carnitine levels showed a deficiency as well. In a second case, a mother known with carnitine deficiency under supplementation was followed throughout her pregnancy. Both pregnancies had an uneventful outcome. Because carnitine deficiency can have serious complications, supplementation with carnitine is advised. This supplementation should be continued throughout pregnancy according to plasma concentrations.

  11. Lanthanoid-free perovskite oxide catalyst for dehydrogenation of ethylbenzene working with redox mechanism

    Directory of Open Access Journals (Sweden)

    Ryo eWatanabe

    2013-10-01

    Full Text Available For the development of highly active and robust catalysts for dehydrogenation of ethylbenzene (EBDH to produce styrene; an important monomer for polystyrene production, perovskite-type oxides were applied to the reaction. Controlling the mobility of lattice oxygen by changing the structure of Ba1–xSrxFeyMn1–yO3–d(0 ≤ x≤ 1, 0.2 ≤ y≤ 0.8, perovskite catalyst showed higher activity and stability on EBDH. The optimized Ba/Sr and Fe/Mn molar ratios were 0.4/0.6 and 0.6/0.4, respectively. Comparison of the dehydrogenation activity of Ba0.4Sr0.6Fe0.6Mn0.4O3–d catalyst with that of an industrial potassium promoted iron (Fe–K catalyst revealed that the Ba0.4Sr0.6Fe0.6Mn0.4O3–d catalyst showed higher initial activity than the industrial Fe–K oxide catalyst. Additionally, the Ba0.4Sr0.6Fe0.6Mn0.4O3–d catalyst showed high activity and stability under severe conditions, even at temperatures as low as 783 K, or at the low steam/EB ratio of 2, while, the Fe–K catalyst showed low activity in such conditions. Comparing reduction profiles of the Ba0.4Sr0.6Fe0.6Mn0.4O3–d and the Fe–K catalysts in aH2O/H2 atmosphere, reduction was suppressed by the presence of H2O over the Ba0.4Sr0.6Fe0.6Mn0.4O3–d catalyst while the Fe–K catalyst was reduced. In other words, Ba0.4Sr0.6Fe0.6Mn0.4O3–d catalyst had higher potential for activating the steam than the Fe–K catalyst. The lattice oxygen in perovskite-structure was consumed by H2, subsequently the consumed lattice oxygen was regenerated by H2O. So the catalytic performance of Ba0.4Sr0.6Fe0.6Mn0.4O3–d was superior to that of Fe–K catalyst thanks to the high redox property of the Ba0.4Sr0.6Fe0.6Mn0.4O3–d perovskite oxide.

  12. Stability and catalytic performance of vanadia supported on nanostructured titania catalyst in oxidative dehydrogenation of propane

    Science.gov (United States)

    Kootenaei, A. H. Shahbazi; Towfighi, J.; Khodadadi, A.; Mortazavi, Y.

    2014-04-01

    Titanate nanotubes with a high specific surface area were synthesized by the simple hydrothermal method and investigated as support for V2O5 catalyst in oxidative dehydrogenation of propane (ODP). The structures of pristine nanotubes as well as the prepared catalysts were investigated by XRD, Raman, FTIR, HRTEM, SEM, EDS, BET, and XPS techniques. The characterization of the as-synthesized nanotubes showed the synthesis of hydrogen titanate nanotube. The incipient wetness impregnation method was utilized to prepare VTNT-x (x = 5, 10, and 15 wt.% vanadia supported on nanotube) together with VTi5 (5 wt.% vanadia supported on Degussa P25). The anatase phase was developed in VTNT-x catalysts upon calcination along with specific surface area loss. Higher vanadia loading resulted in the lowering of support capacity in maintaining vanadia in dispersed state such that eventually crystalline vanadia appeared. The measured catalyst activity demonstrates that in spite of major support surface area loss in VTNT-5 catalyst, the propylene yield is superior in comparison with VTi5 catalyst. The catalyst activity can be correlated with maximum reduction temperature. Deactivation of VTi5 and VTNT-5 as well as VTNT-15 were studied for 3,000 min time-on-stream. It was found that the activity of VTNT-5 catalyst remain unchanged while a decline in catalytic activity observed in VTi5 and VTNT-15 catalysts. The development of rutile was considered as being a major element in the deactivation of the investigated catalysts which is influenced by the presence of vanadium and reaction atmosphere.

  13. Nb effect in the nickel oxide-catalyzed low-temperature oxidative dehydrogenation of ethane

    KAUST Repository

    Zhu, Haibo

    2012-01-01

    A method for the preparation of NiO and Nb-NiO nanocomposites is developed, based on the slow oxidation of a nickel-rich Nb-Ni gel obtained in citric acid. The resulting materials have higher surface areas than those obtained by the classical evaporation method from nickel nitrate and ammonium niobium oxalate. These consist in NiO nanocrystallites (7-13 nm) associated, at Nb contents >3 at.%., with an amorphous thin layer (1-2 nm) of a niobium-rich mixed oxide with a structure similar to that of NiNb 2O 6. Unlike bulk nickel oxides, the activity of these nanooxides for low-temperature ethane oxidative dehydrogenation (ODH) has been related to their redox properties. In addition to limiting the size of NiO crystallites, the presence of the Nb-rich phase also inhibits NiO reducibility. At Nb content >5 at.%, Nb-NiO composites are thus less active for ethane ODH but more selective, indicating that the Nb-rich phase probably covers part of the unselective, non-stoichiometric, active oxygen species of NiO. This geometric effect is supported by high-resolution transmission electron microscopy observations. The close interaction between NiO and the thin Nb-rich mixed oxide layer, combined with possible restructuration of the nanocomposite under ODH conditions, leads to significant catalyst deactivation at high Nb loadings. Hence, the most efficient ODH catalysts obtained by this method are those containing 3-4 at.% Nb, which combine high activity, selectivity, and stability. The impact of the preparation method on the structural and catalytic properties of Nb-NiO nanocomposites suggests that further improvement in NiO-catalyzed ethane ODH can be expected upon optimization of the catalyst. © 2011 Elsevier Inc. All rights reserved.

  14. Modeling-based optimization of a fixed-bed industrial reactor for oxidative dehydrogenation of propane

    Institute of Scientific and Technical Information of China (English)

    Ali Darvishi; Razieh Davand; Farhad Khorasheh; Moslem Fattahi

    2016-01-01

    An industrial scale propylene production via oxidative dehydrogenation of propane (ODHP) in multi-tubular re-actors was modeled. Multi-tubular fixed-bed reactor used for ODHP process, employing 10000 of smal diameter tubes immersed in a shel through a proper coolant flows. Herein, a theory-based pseudo-homogeneous model to describe the operation of a fixed bed reactor for the ODHP to correspondence olefin over V2O5/γ-Al2O3 catalyst was presented. Steady state one dimensional model has been developed to identify the operation parameters and to describe the propane and oxygen conversions, gas process and coolant temperatures, as well as other pa-rameters affecting the reactor performance such as pressure. Furthermore, the applied model showed that a double-bed multitubular reactor with intermediate air injection scheme was superior to a single-bed design due to the increasing of propylene selectivity while operating under lower oxygen partial pressures resulting in propane conversion of about 37.3%. The optimized length of the reactor needed to reach 100%conversion of the oxygen was theoretically determined. For the single-bed reactor the optimized length of 11.96 m including 0.5 m of inert section at the entrance region and for the double-bed reactor design the optimized lengths of 5.72 m for the first and 7.32 m for the second reactor were calculated. Ultimately, the use of a distributed oxygen feed with limited number of injection points indicated a significant improvement on the reactor performance in terms of propane conversion and propylene selectivity. Besides, this concept could overcome the reactor run-away temperature problem and enabled operations at the wider range of conditions to obtain enhanced propyl-ene production in an industrial scale reactor.

  15. Ni–Ta–O mixed oxide catalysts for the low temperature oxidative dehydrogenation of ethane to ethylene

    KAUST Repository

    Zhu, Haibo

    2015-09-01

    The "wet" sol-gel and "dry" solid-state methods were used to prepare Ni-Ta-O mixed oxide catalysts. The resulting Ni-Ta oxides exhibit high activity and selectivity for the low temperature oxidative dehydrogenation of ethane to ethylene. The Ta/(Ni + Ta) atomic ratios (varying from 0 to 0.11 in "wet" sol-gel method, and from 0 to 0.20 in "dry" solid-state method) as well as the preparation methods used in the synthesis, play important roles in controlling catalyst structure, activity, selectivity and stability in the oxidative dehydrogenation of ethane. Electron microscopy characterizations (TEM, EELS mapping, and HAADF-STEM) clearly demonstrate that the Ta atoms are inserted into NiO crystal lattice, resulting in the formation of a new Ni-Ta oxide solid solution. More Ta atoms are found to be located at the lattice sites of crystal surface in sol-gel catalyst. While, a small amount of thin layer of Ta2O5 clusters are detected in solid-state catalyst. Further characterization by XRD, N2 adsorption, SEM, H2-TPR, XPS, and Raman techniques reveal different properties of these two Ni-Ta oxides. Due to the different properties of the Ni-Ta oxide catalysts prepared by two distinct approaches, they exhibit different catalytic behaviors in the ethane oxidative dehydrogenation reaction at low temperature. Thus, the catalytic performance of Ni-Ta-O mixed oxide catalysts can be systematically modified and tuned by selecting a suitable synthesis method, and then varying the Ta content. ©2015 Elsevier Inc. All rights reserved.

  16. Environmentally benign synthesis of amides and ureas via catalytic dehydrogenation coupling of volatile alcohols and amines in a Pd-Ag membrane reactor

    KAUST Repository

    Chen, Tao

    2016-05-31

    In this study, we report the direct synthesis of amides and ureas via the catalytic dehydrogenation of volatile alcohols and amines using the Milstein catalyst in a Pd-Ag/ceramic membrane reactor. A series of amides and ureas, which could not be synthesized in an open system by catalytic dehydrogenation coupling, were obtained in moderate to high yields via catalytic dehydrogenation of volatile alcohols and amines. This process could be monitored by the hydrogen produced. Compared to the traditional method of condensation, this catalytic system avoids the stoichiometric pre-activation or in situ activation of reagents, and is a much cleaner process with high atom economy. This methodology, only possible by employing the Pd-Ag/ceramic membrane reactor, not only provides a new environmentally benign synthetic approach of amides and ureas, but is also a potential method for hydrogen storage.

  17. Effect of Ce addition on the surface properties and n-dodecane dehydrogenation performance of Pt-Sn/Ce-Al2O3 catalyst

    Science.gov (United States)

    Li, Xianru; He, Songbo; Wei, Huangzhao; Luo, Sha; Gu, Bin; Sun, Chenglin

    2015-08-01

    Ce-modified alumina carriers with different Ce content were prepared by vacuum isovolume impregnation method aiming to improve the n-dodecane catalytic dehydrogenation performance of PtSn/Al2O3 catalyst. The support and catalyst were characterized by XRD, N2 adsorption-desorption, NH3-TPD, H2-TPR, CO-pulse adsorption and TG-DTG. Results showed that Ce addition decreased the surface acid amount significantly and inhibited the reduction of SnO x species. Besides, Ce containing catalyst showed higher n-dodecane dehydrogenation activity and stability and lower coke deposition amount and coke burning temperature. In our study, the optimal Ce addition amount for n-dodecane dehydrogenation was 2%.

  18. The influence of surface oxygen and hydroxyl groups on the dehydrogenation of ethylene, acetic acid and hydrogenated vinyl acetate on pure Pd(1 0 0): A DFT study

    Science.gov (United States)

    Huang, Yanping; Dong, Xiuqin; Yu, Yingzhe; Zhang, Minhua

    2016-12-01

    On the basis of a Langmuir-Hinshelwood-type mechanism, the dehydrogenation of ethylene, acetic acid and hydrogenated vinyl acetate (VAH) on pure Pd(1 0 0) with surface oxygen atoms (Os) and hydroxyl groups (OHs) was studied with density functional theory (DFT) method. Our calculation results show that both Os and OHs can consistently reduce the activation energies of dehydrogenation of ethylene, acetic acid and VAH to some degree with only one exception that OHs somehow increase the activation energy of VAH. Based on Langmuir-Hinshelwood mechanism, the three dehydrogenation reactions in presence of surface Os and OHs are almost consistently favored, compared with the corresponding processes on clean Pd(1 0 0) surfaces, and thus a Langmuir-Hinshelwood-type mechanism may not be excluded beforehand when investigating the microscopic performance of the oxygen-assisted vinyl acetate synthesis on Pd(1 0 0) catalysts.

  19. Coupling dehydrogenation of isobutane in the presence of carbon dioxide over chromium oxide supported on active carbon

    Institute of Scientific and Technical Information of China (English)

    Jian Fei Ding; Zhang Feng Qin; Xue Kuan Li; Guo Fu Wang; Jian Guo Wang

    2008-01-01

    The dehydrogenation of isobutane (IB) to produce isobutene coupled with reverse water gas shift in the presence of carbon dioxide was investigated over the catalyst Cr2O3 supported on active carbon (Cr2O3/AC). The results illustrated that isobutane c onversion and isobutene yield can be enhanced through the reaction coupling in the presence of carbon dioxide. Moreover, carbon dioxide can partially eliminate carbonaceous deposition on the catalyst and keep the active phase (Cr2O3), which are then helpful to alleviate the catalyst deactivation.

  20. Oxidative dehydrogenation of propane with K-MoO3/MgAl2O4 catalysts

    Indian Academy of Sciences (India)

    Serkan Naci Koc; Kubra Dayioglu; Hasan Ozdemir

    2016-01-01

    In this study, for the first time, MoO3/MgAl2O4 catalysts and their potassium-promoted forms were prepared and tested for oxidative dehydrogenation of propane. Catalysts were characterized with XRD, BET, NH3-TPD, TPR and XPS methods. Catalytic activity measurement was done with quartz microreactor between 450 and 550°C. It has been observed that the conversion of propane increased with temperature and total hydrocarbon selectivity increased with molybdenum oxide content. The acidity of catalysts decreased with potassium addition due to interaction with MoO3 sites. For this reason total hydrocarbon selectivity highly increased.

  1. Acquired color vision deficiency.

    Science.gov (United States)

    Simunovic, Matthew P

    2016-01-01

    Acquired color vision deficiency occurs as the result of ocular, neurologic, or systemic disease. A wide array of conditions may affect color vision, ranging from diseases of the ocular media through to pathology of the visual cortex. Traditionally, acquired color vision deficiency is considered a separate entity from congenital color vision deficiency, although emerging clinical and molecular genetic data would suggest a degree of overlap. We review the pathophysiology of acquired color vision deficiency, the data on its prevalence, theories for the preponderance of acquired S-mechanism (or tritan) deficiency, and discuss tests of color vision. We also briefly review the types of color vision deficiencies encountered in ocular disease, with an emphasis placed on larger or more detailed clinical investigations.

  2. Aerobic dehydrogenation of cyclohexanone to phenol catalyzed by Pd(TFA)2/2-dimethylaminopyridine: evidence for the role of Pd nanoparticles.

    Science.gov (United States)

    Pun, Doris; Diao, Tianning; Stahl, Shannon S

    2013-06-05

    We have carried out a mechanistic investigation of aerobic dehydrogenation of cyclohexanones and cyclohexenones to phenols with a Pd(TFA)2/2-dimethylaminopyridine catalyst system. Numerous experimental methods, including kinetic studies, filtration tests, Hg poisoning experiments, transmission electron microscopy, and dynamic light scattering, provide compelling evidence that the initial Pd(II) catalyst mediates the first dehydrogenation of cyclohexanone to cyclohexenone, after which it evolves into soluble Pd nanoparticles that retain catalytic activity. This nanoparticle formation and stabilization is facilitated by each of the components in the catalytic reaction, including the ligand, TsOH, DMSO, substrate, and cyclohexenone intermediate.

  3. Kinetic and thermodynamic parameters of hydrogen release during the heterogeneous catalytic dehydrogenation of cis- and trans-isomers of perhydro-m-terphenyl

    Science.gov (United States)

    Kalenchuk, A. N.; Bogorodskii, S. E.; Bogdan, V. I.

    2016-10-01

    Comparative studies on the temperature dependence of the dehydrogenation of cis- and trans-isomers of perhydro- m-terphenyl are performed in a flow catalytic reactor. Rate constants and equilibrium constants of all elementary acts of this reaction are calculated on basis of experimental data using the KINET 0.8 program for the mathematical modeling of the kinetics of complex reactions. The resulting data indicate that perhydro- m-terphenyl cis- and trans-isomers structural differences have no appreciable effect on dehydrogenation.

  4. Synthesis of 2-oxindoles via 'transition-metal-free' intramolecular dehydrogenative coupling (IDC) of sp2 C–H and sp3 C–H bonds

    Science.gov (United States)

    Bhunia, Subhajit

    2016-01-01

    Summary The synthesis of a variety of 2-oxindoles bearing an all-carbon quaternary center at the pseudo benzylic position has been achieved via a ‘transition-metal-free’ intramolecular dehydrogenative coupling (IDC). The construction of 2-oxindole moieties was carried out through formation of carbon–carbon bonds using KOt-Bu-catalyzed one pot C-alkylation of β-N-arylamido esters with alkyl halides followed by a dehydrogenative coupling. Experimental evidences indicated toward a radical-mediated path for this reaction. PMID:27559367

  5. Microcalorimetric Adsorption of Alumina Oxide Catalysts for Combination of Ethylbenzene dehydrogenation and carbon Dioxide Shift-reaction

    Institute of Scientific and Technical Information of China (English)

    GE Xin; SHEN Jian-yi

    2004-01-01

    Styrene (STY) is now produced industrially in fairly large quantities by the dehydrogenation of ethylbenzene (EB) using promoted iron oxide catalyst with superheated steam.In this case, small amount of carbon dioxide formed as a by-product was known to inhibit the catalytic activity of commercial catalyst. Recently, there have been some reports which carbon dioxide showed positive effects to promote catalytic activities on the reaction over several catalysts.In this study, we attempted to combine the dehydrogenation of EB to STY with the carbon dioxide shift-reaction. The combine reaction (EB + CO2 → STY + H2O + CO) can be considered as one of the ways of using CO2 resources and can yield simultaneously STY and Carbon oxide.Alumina oxide catalysts such as Al2O3, Na2O/Al2O3 and K2O/Al2O3 were prepared by the usual impregnation method with an aqueous solution of NaNO3 and KNO3, and then calcined at 650℃ for 5 h in a stream of air. The reaction condition is 600℃, flow of CO2 38ml/mon and space velocity (EB) 1.28h-1.

  6. Ru-N-C Hybrid Nanocomposite for Ammonia Dehydrogenation: Influence of N-doping on Catalytic Activity

    Directory of Open Access Journals (Sweden)

    Nguyen Thi Bich Hien

    2015-06-01

    Full Text Available For application to ammonia dehydrogenation, novel Ru-based heterogeneous catalysts, Ru-N-C and Ru-C, were synthesized via simple pyrolysis of a mixture of RuCl3·6H2O and carbon black with or without dicyandiamide as a nitrogen-containing precursor at 550 °C. Characterization of the prepared Ru-N-C and Ru-C catalysts via scanning transmission electron microscopy, in conjunction with energy dispersive X-ray spectroscopy, indicated the formation of hollow nanocomposites in which the average sizes of the Ru nanoparticles were 1.3 nm and 5.1 nm, respectively. Compared to Ru-C, the Ru-N-C nanocomposites not only proved to be highly active for ammonia dehydrogenation, giving rise to a NH3 conversion of >99% at 550 °C, but also exhibited high durability. X-ray photoelectron spectroscopy revealed that the Ru active sites in Ru-N-C were electronically perturbed by the incorporated nitrogen atoms, which increased the Ru electron density and ultimately enhanced the catalyst activity.

  7. VO x /SiO 2 Catalyst Prepared by Grafting VOCl 3 on Silica for Oxidative Dehydrogenation of Propane

    KAUST Repository

    Zhu, Haibo

    2015-09-07

    The VOx/SiO2 catalysts for oxidative dehydrogenation of propane were synthesized by a simple grafting method. The VOCl3 was first grafted at the surface of SiO2, which was dehydrated at different temperature (from 200 to 1000°C). The formed grafted complexes were then calcined in air, leading to the formation of VOx/SiO2 catalysts. The synthesized catalysts were characterized by nitrogen adsorption, SEM, Raman spectroscopy, temperature-programmed reduction, and extended X-ray absorption fine structure analysis. The SiO2 pretreatment temperature has an evident effect on the loading and dispersion of VOx on SiO2, which finally affects their catalytic performance. High SiO2 treatment temperature is beneficial to dispersing the vanadium oxide species at the SiO2 surface. These materials are efficient catalysts for the catalytic oxidative dehydrogenation of propane to propylene. The best selectivity to propylene is achieved on the VOx/SiO2-(1000) catalyst. The high selectivity and activity are well maintained for three days catalytic reaction. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Cu, Fe, or Ni doped molybdenum oxide supported on Al2O3 for the oxidative dehydrogenation of ethylbenzene

    Institute of Scientific and Technical Information of China (English)

    Tiago Pinheiro Braga; Antônio Narcísio Pinheiro; Edson R. Leite; Regina Cláudia R. dos Santos; Antoninho Valentini

    2015-01-01

    Molybdenum-based catalysts supported on Al2O3 doped with Ni, Cu, or Fe oxide were synthesized and used in ethylbenzene dehydrogenation to produce styrene. The molybdenum oxide was sup-ported using an unconventional route that combined the polymeric precursor method (Pechini) and wet impregnation on commercial alumina. The samples were characterized by X-ray diffraction (XRD), N2 adsorption-desorption isotherms, temperature-programmed reduction of H2 (H2-TPR), and thermogravimetric (TG) analysis. XRD results showed that the added metals were well dis-persed on the alumina support. The addition of the metal oxide (Ni, Cu, or Fe) of 2 wt% by wet im-pregnation did not affect the texture of the support. TPR results indicated a synergistic effect be-tween the dopant and molybdenum oxide. The catalytic tests showed ethylbenzene conversion of 28%–53% and styrene selectivity of 94%–97%, indicating that the addition of the dopant improved the catalytic performance, which was related to the redox mechanism. Molybdenum oxides play a fundamental role in the oxidative dehydrogenation of ethylbenzene to styrene by its redox and acid–base properties. The sample containing Cu showed an atypical result with increasing conver-sion during the reaction, which was due to metal reduction. The Ni-containing solid exhibited the highest amount of carbon deposited, shown by TG analysis after the catalytic test, which explained its lower catalytic stability and selectivity.

  9. A New Solid Sorbent System for Rapid Monitoring of Dehydrogenated Nicotine by Using Furfural-hydrochloric Acid

    Institute of Scientific and Technical Information of China (English)

    B. AMBADE; E. K. JANGHEL; M. K. RAI; G. L. MUNDHARA

    2006-01-01

    A new solid sorbent system is developed for the monitoring of dehydrogenated nicotine in the environment. The reagent system for the indicator tube consists of furfural-hydrochloric acid and phosphoric acid impregnated over a cellulose fibre (cotton) and a humectant calcium chloride. The reagent system has also been used for the preparation of reagent paper. After exposing the indicator tubes and test paper to dehydrogenated nicotine, for a constant time, the red-violet colour developed could be compared with those obtained from standards. Alternatively the coloured compound was extracted in water and the absorbance measured at 540 nm. The lower limit of detection is 0.03 μg/m3 of nicotine for the reagent papers and indicator tubes. The lower limit of determination by spectrophotometric procedure is 0.001 μg/m3 of air.The preparation of indicator tubes, test papers and their applications for the detection and determination of nicotine in environmental tobacco smoke (ETS), mainstream smoke (MS), side stream smoke (SS) and biological samples is described in this paper.

  10. Mo-V-Te-Nb oxides as catalysts for ethene production by oxidative dehydrogenation of ethane

    Energy Technology Data Exchange (ETDEWEB)

    Hartmann, D. [Technische Universitaet Muenchen, Garching (Germany). Dept. of Chemistry and Catalysis Research Center; Meiswinkel, A.; Thaller, C.; Bock, M.; Alvarado, L. [Linde AG, Pullach (Germany)

    2013-11-01

    The availability of ethane in shale gas, as well as the interest in valorising previously underutilized carbon feedstocks, makes the oxidative dehydrogenation (ODH) of ethane an attractive alternative to the industrially established processes for production of ethylene. Mo-V-Te-Nb mixed oxide has been chosen as catalyst for the ODH reaction in view of its outstanding ability to activate alkane molecules. Catalytic test results showed that this type of catalyst can selectively oxidize ethane to ethene at moderate temperatures (350-400 C) with minor production of CO{sub x}. The catalytic performance of Mo-V-Te-Nb mixed-oxide is mainly attributable to the crystalline phase 'M1'. Rietveld analysis of the X-Ray diffractograms allowed us to quantify the amount of MoVTeNb oxide that has crystallized as M1. In this way, it was possible to find a linear correlation of the reaction rate with the abundance of M1 in the solid. Therefore, it is clear that for improving the efficiency of MoVTeNb oxide in ODH, the amount of M1 in the catalyst should be maximized. With this purpose, several MoVTeNb oxides were subject to different thermal treatments prior to the catalytic test. Structural changes in the catalyst were monitored by in-situ XRD technique. Under oxidative atmosphere, it was observed a recrystallization of M2 and possibly, amorphous oxide, into M1 phase, leading to correspondingly more active and selective catalysts (selectivities above 95 % for ethane conversions up to 40 % under industrially relevant conditions). The active site of M1 involves V species, likely with redox properties enhanced by the proximity of Mo and Te species, while the function of the crystalline structure itself is to provide the spatial configuration that allows interaction between these species. However, ethene formation rate was observed to be independent of the V content of the samples. The vanadium species exposed at the surface were studied by LEIS and by IR spectroscopy of CO

  11. Heterogeneous Partial (ammOxidation and Oxidative Dehydrogenation Catalysis on Mixed Metal Oxides

    Directory of Open Access Journals (Sweden)

    Jacques C. Védrine

    2016-01-01

    Full Text Available This paper presents an overview of heterogeneous partial (ammoxidation and oxidative dehydrogenation (ODH of hydrocarbons. The review has been voluntarily restricted to metal oxide-type catalysts, as the partial oxidation field is very broad and the number of catalysts is quite high. The main factors of solid catalysts for such reactions, designated by Grasselli as the “seven pillars”, and playing a determining role in catalytic properties, are considered to be, namely: isolation of active sites (known to be composed of ensembles of atoms, Me–O bond strength, crystalline structure, redox features, phase cooperation, multi-functionality and the nature of the surface oxygen species. Other important features and physical and chemical properties of solid catalysts, more or less related to the seven pillars, are also emphasized, including reaction sensitivity to metal oxide structure, epitaxial contact between an active phase and a second phase or its support, synergy effect between several phases, acid-base aspects, electron transfer ability, catalyst preparation and activation and reaction atmospheres, etc. Some examples are presented to illustrate the importance of these key factors. They include light alkanes (C1–C4 oxidation, ethane oxidation to ethylene and acetic acid on MoVTe(SbNb-O and Nb doped NiO, propene oxidation to acrolein on BiMoCoFe-O systems, propane (ammoxidation to (acrylonitrile acrylic acid on MoVTe(SbNb-O mixed oxides, butane oxidation to maleic anhydride on VPO: (VO2P2O7-based catalyst, and isobutyric acid ODH to methacrylic acid on Fe hydroxyl phosphates. It is shown that active sites are composed of ensembles of atoms whose size and chemical composition depend on the reactants to be transformed (their chemical and size features and the reaction mechanism, often of Mars and van Krevelen type. An important aspect is the fact that surface composition and surface crystalline structure vary with reaction on stream until

  12. Mechanistic and kinetic analysis of the oxidative dehydrogenation of ethane via novel supported alkali chloride catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Gaertner, C.; Veen, A.C. van; Lercher, J.A. [Technische Universitaet Muenchen (Germany). Catalysis Research Center

    2013-11-01

    The oxidative dehydrogenation of ethane over advanced catalysts is promising to selectively produce ethylene, an essential building block for the chemical industry. In this way, ethane from shale gas can be efficiently valorized. Supported alkali chloride catalysts are investigated in this work. Essential feature of those materials is the presence of a solid core (magnesium oxide in part doped with Dy{sub 2}O{sub 3}) covered under reaction conditions with a molten alkali chloride shell. It is shown that especially the lowered melting point of eutectic mixtures of LiCl with other alkali/alkaline earth metals is the key to taylor highly efficient materials. Elucidating the ODH reaction mechanism is essential to understand the reactivity of this novel catalyst class and provides the basis for improving performances. Information about elementary steps and the rate determining step were extracted from kinetic measurements, both in steady state and in transient configuration. Furthermore, isotopic labelling studies were performed, i.e. SSITKA studies and temperature programmed isotopic exchange experiments. Step experiments showed a significant oxygen uptake by the catalysts. Retained oxygen reacted quantitatively with ethane at nearly 100% selectivity to ethylene and conversion rates were comparable with rates observed during steady state operation. Thus, chemically bound oxygen in the melt is the active and selective intermediate in the ODH. Therefore, it is required to consider an intermediate and the activation is concluded to relate to the oxygen dissociation. The total concentration of stored oxygen can be correlated to the steady-state activity, while the viscosity of the melts mainly influences the selectivity towards ethene. Properties of the solid core impact on the catalyst efficiency suggesting that the oxygen species forms at the interface between support and overlayer. The quantity of retained oxygen additionally depends on the properties of the chloride

  13. Deficiently Extremal Gorenstein Algebras

    Indian Academy of Sciences (India)

    Pavinder Singh

    2011-08-01

    The aim of this article is to study the homological properties of deficiently extremal Gorenstein algebras. We prove that if / is an odd deficiently extremal Gorenstein algebra with pure minimal free resolution, then the codimension of / must be odd. As an application, the structure of pure minimal free resolution of a nearly extremal Gorenstein algebra is obtained.

  14. Iron deficiency anemia

    Science.gov (United States)

    Anemia - iron deficiency ... iron from old red blood cells. Iron deficiency anemia develops when your body's iron stores run low. ... You may have no symptoms if the anemia is mild. Most of the time, ... slowly. Symptoms may include: Feeling weak or tired more often ...

  15. Muscle phosphorylase kinase deficiency

    DEFF Research Database (Denmark)

    Preisler, N; Orngreen, M C; Echaniz-Laguna, A;

    2012-01-01

    To examine metabolism during exercise in 2 patients with muscle phosphorylase kinase (PHK) deficiency and to further define the phenotype of this rare glycogen storage disease (GSD).......To examine metabolism during exercise in 2 patients with muscle phosphorylase kinase (PHK) deficiency and to further define the phenotype of this rare glycogen storage disease (GSD)....

  16. Growth Hormone Deficiency

    Directory of Open Access Journals (Sweden)

    Ömer Tarım

    2010-05-01

    Full Text Available Growth hormone deficiency is the most promising entity in terms of response to therapy among the treatable causes of growth retardation. It may be due to genetic or acquired causes. It may be isolated or a part of multiple hormone deficiencies. Diagnostic criteria and therefore treatment indications are still disputed. (Journal of Current Pediatrics 2010; 8: 36-8

  17. Iron induced nickel deficiency

    Science.gov (United States)

    It is increasingly apparent that economic loss due to nickel (Ni) deficiency likely occurs in horticultural and agronomic crops. While most soils contain sufficient Ni to meet crop requirements, situations of Ni deficiency can arise due to antagonistic interactions with other metals. This study asse...

  18. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Blood Tests Blood Transfusion Restless Legs Syndrome Send a link to NHLBI to someone by E-MAIL | ... Iron-Deficiency Anemia? Español Iron-deficiency anemia is a common, easily treated condition that occurs if you ...

  19. Nutritional iron deficiency

    NARCIS (Netherlands)

    Zimmermann, M.B.; Hurrell, R.F.

    2007-01-01

    Iron deficiency is one of the leading risk factors for disability and death worldwide, affecting an estimated 2 billion people. Nutritional iron deficiency arises when physiological requirements cannot be met by iron absorption from diet. Dietary iron bioavailability is low in populations consuming

  20. Iron deficiency in childhood

    NARCIS (Netherlands)

    Uijterschout, L.

    2015-01-01

    Iron deficiency (ID) is the most common micronutrient deficiency in the world. Iron is involved in oxygen transport, energy metabolism, immune response, and plays an important role in brain development. In infancy, ID is associated with adverse effects on cognitive, motor, and behavioral development

  1. DDQ-promoted dehydrogenation from natural rigid polycyclic acids or flexible alkyl acids to generate lactones by a radical ion mechanism.

    Science.gov (United States)

    Ding, Ye; Huang, Zhangjian; Yin, Jian; Lai, Yisheng; Zhang, Shibo; Zhang, Zhiguo; Fang, Lei; Peng, Sixun; Zhang, Yihua

    2011-09-07

    A novel and facile DDQ-mediated dehydrogenation from natural rigid polycyclic acids or flexible alkyl acids to generate lactones is described. The formation of lactones proceeds by a radical ion mechanism, which has been established by DPPH˙-mediated chemical identification, ESR spectroscopy and an enol intermediate trapping.

  2. Reversible cyclometalation at Rh-I as a motif for metal-ligand bifunctional bond activation and base-free formic acid dehydrogenation

    NARCIS (Netherlands)

    Jongbloed, L.S.; de Bruin, B.; Reek, J.N.H.; Lutz, M.; van der Vlugt, J.I.

    2016-01-01

    Reversible cyclometalation is demonstrated as a strategy for the activation of small protic molecules, with a proof-of-principle catalytic application in the dehydrogenation of formic acid in the absence of an exogenous base. The well-defined RhI complex Rh(CO)(L) 1, bearing the reactive cyclometala

  3. Reversible cyclometalation at RhI as a motif for metal–ligand bifunctional bond activation and base-free formic acid dehydrogenation

    NARCIS (Netherlands)

    Jongbloed, L. S.; De Bruin, B.; Reek, J. N. H.; Lutz, M.|info:eu-repo/dai/nl/304828971; Van Der Vlugt, J. I.

    2016-01-01

    Reversible cyclometalation is demonstrated as a strategy for the activation of small protic molecules, with a proof-of-principle catalytic application in the dehydrogenation of formic acid in the absence of an exogenous base. The well-defined RhI complex Rh(CO)(L) 1, bearing the reactive cyclometala

  4. On the stability of conventional and nano-structured carbon-based catalysts in the oxidative dehydrogenation of ethylbenzene under industrially relevant conditions

    NARCIS (Netherlands)

    Zarubina, Valeriya; Talebi, Hesamoddin; Nederlof, Christian; Kapteijn, Freek; Makkee, Michiel; Melian-Cabrera, Ignacio

    2014-01-01

    Relevant carbon-based materials, home-made carbon-silica hybrids, commercial activated carbon, and nanostructured multi-walled carbon nanotubes (MWCNT) were tested in the oxidative dehydrogenation of ethylbenzene (EB). Special attention was given to the reaction conditions, using a relatively concen

  5. Dehydrogenation kinetics for pure and nickel-doped magnesium hydride investigated by in-situ, time-resolved powder diffraction (poster)

    DEFF Research Database (Denmark)

    Jensen, T.R.; Andreasen, A.; Vegge, T.;

    2004-01-01

    under isothermal conditions with a time resolution of 45 s. Three phases were identified, Mg,MgH2 and MgO, and the phase fractions were extracted for each phase. Dehydrogenation curves wereconstructed and analyzed by the Johnson-Mehl-Avrami formalism in order to derive rateconstants at different...

  6. Direct Dehydrogenation of n-Butane Over Pt/Sn/Zn-K/Al2O3 Catalyst: Effect of Hydrogen in the Feed.

    Science.gov (United States)

    Lee, Jong Kwon; Seo, Hyun; Kim, Jeong Kwon; Seo, Hanuk; Cho, Hye-Ran; Lee, Jinsuk; Chang, Hosik; Song, In Kyu

    2016-05-01

    Al2O3 was prepared by a sol-gel method for use as a support. Pt/Sn/Zn-K/Al2O3 catalyst was then prepared by a sequential impregnation method, and it was applied to the direct dehydrogenation of n-butane to n-butenes and 1,3-butadiene. Physicochemical properties of Pt/Sn/Zn-K/Al2O3 catalyst were examined by X-ray diffraction (XRD), nitrogen adsorption-desorption isotherm, inductively coupled plasma atomic emission spectroscopy (ICP-AES), temperature-programmed reduction (TPR), CO chemisorption, and temperature-programmed oxidation (TPO) measurements. In order to improve the catalyst stability, the effect of hydrogen in the feed on the catalytic performance in the direct dehydrogenation of n-butane was studied. The catalyst stability and reusability in the direct dehydrogenation of n-butane was also investigated. Experimental results revealed that the addition of hydrogen in the feed decreased conversion of n-butane and yield for total dehydrogenation products but improved the stability of the catalyst. The catalytic activity and stability of regenerated Pt/Sn/Zn-K/Al2O3 catalyst in the presence of hydrogen slightly decreased compared to those of fresh Pt/Sn/Zn-K/Al2O3 catalyst due to the slight sintering of platinum particles.

  7. Carbon covered alumina prepared by the pyrolysis of sucrose: A promising support material for the supported Pt-Sn-bimetallic dehydrogenation catalysis

    NARCIS (Netherlands)

    Luo, S.; He, S.; Li, X.R.; Seshan, K.

    2014-01-01

    Sucrose was pyrolyzed on gamma alumina surface to prepare carbon covered alumina (CCA) material. Alumina and CCA supported Pt–Sn catalysts were prepared by the complex impregnation method under vacuum. Dehydrogenation of n-octadecane was performed to study the effect of carbon addition, Pt loading a

  8. Effective participation of Li4(NH2)3BH4 in the dehydrogenation pathway of the Mg(NH2)2-2LiH composite.

    Science.gov (United States)

    Amica, G; Cova, F; Arneodo Larochette, P; Gennari, F C

    2016-07-21

    Lithium fast-ion conductors have shown positive effects on the hydrogen storage properties of the Li-Mg-N-H system. In the present work, Li4(NH2)3BH4 doped Mg(NH2)2-2LiH was formed by milling the 2LiNH2-MgH2-0.2LiBH4 composite and posterior annealing under hydrogen pressure to reduce the kinetic barrier of the Li-Mg-N-H system. The effect of repetitive dehydrogenation/rehydrogenation cycles on the kinetic and thermodynamic performance was evaluated. The dehydrogenation rate in the doped composite was twice that in the un-doped sample at 200 °C, while hydrogenation was 20 times faster. The activation energy decreases by 9% due to the presence of Li4(NH2)3BH4 compared to the un-doped composite, evidencing its catalytic role. The presence of Li4(NH2)3BH4 in the composite stabilized the hydrogen storage capacity after successive sorption cycles. Thermodynamic studies revealed a variation in the pressure composition isotherm curves between the first dehydrogenation cycle and the subsequent. The Li4(NH2)3BH4 doped composite showed a sloped plateau region at higher equilibrium pressure in regard to the flat plateau of the un-doped composite. Detailed structural investigations revealed the effective influence of Li4(NH2)3BH4 in different reactions: the irreversible dehydrogenation in the presence of MgH2 and the reversible hydrogen release when it reacts with Li2Mg2(NH)3. The role of Li4(NH2)3BH4 in improving the dehydrogenation kinetics is associated with the weakening of the N-H bond and the mobile small ion mass transfer enhancement.

  9. Copper-based nanocatalysts for 2-butanol dehydrogenation: Screening and optimization of preparation parameters by response surface methodology

    Energy Technology Data Exchange (ETDEWEB)

    Geravand, Elham; Shariatinia, Geravand; Yaripour, Fereydoon [Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Sahebdelfar, Saeed [National Iranian Petrochemical Company, P. O. Box 1493, Tehran (Iran, Islamic Republic of)

    2015-12-15

    Two types of copper-based dehydrogenation nanocatalysts (Cu/ZnO/Al{sub 2}O{sub 3} and Cu/SiO{sub 2}) were prepared from various precursors by impregnation (IM), sol-gel (SG) and co precipitation (COPRE) methods. The structures of samples were characterized by N{sub 2} adsorption-desorption, XRD, XRF, TPR, N{sub 2}O-Titration, FT-IR, FE-SEM and TEM techniques. The catalytic performance tests in vapor-phase dehydrogenation of 2-butanol to methyl ethyl ketone (MEK) were carried out in a fixed-bed reactor at a temperature of 260 .deg. C under atmospheric pressure and LHSV of 4mL/(h·g cat). The experimental results indicated that (i) the copper oxide over the COPRE nanocatalyst was reduced at a lower temperature (222 .deg. C) in comparison with the CuO reduced on the SG and IM samples (243 and 327 .deg. C, respectively). Also, the percentage of reduction of CuO species on COPRE catalyst was the highest (98.8%) in comparison with the two other samples, (ii) the COPRE nanocatalyst exhibited the highest activity for the dehydrogenation of 2-butanol to MEK, and (iii) co-precipitation method was selected as an optimum method for preparation of nanocatalyst. The central composite experimental design method was applied for investigation of the effects of four critical preparation factors on the MEK selectivity of Cu/ZnO/Al{sub 2}O{sub 3} nanocatalyst. The results showed that Cu/Zn molar ratio and precipitation pH are the most effective factors on the response and the optimum conditions for synthesis of Cu/ZnO/Al{sub 2}O{sub 3} nanocatalyst with maximum selectivity of MEK were T(pre)=67.5 .deg. C, T(aging)=68.8 .deg. C, pH(pre)=7.27 and Cu/Zn molar ratio=1.38. The performance of the prepared nanocatalyst at the optimum conditions was comparable to the commercially available nanocatalyst.

  10. Genotypic and phenotypic spectrum of pyridoxine-dependent epilepsy (ALDH7A1 deficiency)

    DEFF Research Database (Denmark)

    Mills, Philippa B; Footitt, Emma J; Mills, Kevin A;

    2010-01-01

    Pyridoxine-dependent epilepsy was recently shown to be due to mutations in the ALDH7A1 gene, which encodes antiquitin, an enzyme that catalyses the nicotinamide adenine dinucleotide-dependent dehydrogenation of l-alpha-aminoadipic semialdehyde/L-Delta1-piperideine 6-carboxylate. However, whilst...... with suspected or clinically proven pyridoxine-dependent epilepsy and to characterize further the phenotypic spectrum of antiquitin deficiency. Urinary L-alpha-aminoadipic semialdehyde concentration was determined by liquid chromatography tandem mass spectrometry. When this was above the normal range, DNA......, through abnormal foetal movements and a multisystem neonatal disorder, to the onset of seizures and autistic features after the first year of life. Our relatively large series suggested that clinical diagnosis of pyridoxine dependent epilepsy can be challenging because: (i) there may be some response...

  11. Crystal chemistry of volcanic allanites indicative of naturally induced oxidation-dehydrogenation

    Science.gov (United States)

    Hoshino, Mihoko; Kimata, Mitsuyoshi; Chesner, Craig A.; Nishida, Norimasa; Shimizu, Masahiro; Akasaka, Takeshi

    2010-05-01

    welding of the Youngest Toba Tuff caused the following post-crystallization changes to occur in YTT allanite: oxidation of Fe2+ to Fe3+, release of H2, and the concomitant replacement of OH- by O2-. These oxidation and dehydrogenation processes advanced during the welding to thereby produce oxyallanite. Oxyallanite had been reported only in laboratory studies where it was produced by heating natural allanite. Our report on natural oxyallanite suggests that it may be present in other welded silicic volcanic rocks as well.

  12. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... chest pain, and other symptoms. Severe iron-deficiency anemia can lead to heart problems, infections, problems with growth and development in children, and other complications. Infants and young children and ...

  13. Vitamin D Deficiency

    Science.gov (United States)

    ... fractures), muscle weakness, and the bone-thinning disease osteoporosis. Severe vitamin D deficiency can cause rickets in children and osteomalacia in adults. Both problems cause soft, weak bones, as well ...

  14. Factor II deficiency

    Science.gov (United States)

    ... if one or more of these factors are missing or are not functioning like they should. Factor II is one such coagulation factor. Factor II deficiency runs in families (inherited) and is very rare. Both parents must ...

  15. Factor VII deficiency

    Science.gov (United States)

    ... if one or more of these factors are missing or are not functioning like they should. Factor VII is one such coagulation factor. Factor VII deficiency runs in families (inherited) and is very rare. Both parents must ...

  16. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Events Spokespeople Email Alerts E-Newsletters About NHLBI Organization NHLBI Director Budget, Planning, & Legislative Advisory Committees Jobs ... food. Overview Iron-deficiency anemia is a common type of anemia . The term "anemia" usually refers to ...

  17. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... CAUSES WHO IS AT RISK SIGNS & SYMPTOMS DIAGNOSIS TREATMENTS PREVENTION LIVING WITH CLINICAL TRIALS LINKS Related Topics ... Doctors usually can successfully treat iron-deficiency anemia. Treatment will depend on the cause and severity of ...

  18. Manganese deficiency in plants

    DEFF Research Database (Denmark)

    Schmidt, Sidsel Birkelund; Jensen, Poul Erik; Husted, Søren

    2016-01-01

    Manganese (Mn) is an essential plant micronutrient with an indispensable function as a catalyst in the oxygen-evolving complex (OEC) of photosystem II (PSII). Even so, Mn deficiency frequently occurs without visual leaf symptoms, thereby masking the distribution and dimension of the problem...... restricting crop productivity in many places of the world. Hence, timely alleviation of latent Mn deficiency is a challenge in promoting plant growth and quality. We describe here the key mechanisms of Mn deficiency in plants by focusing on the impact of Mn on PSII stability and functionality. We also address...... the mechanisms underlying the differential tolerance towards Mn deficiency observed among plant genotypes, which enable Mn-efficient plants to grow on marginal land with poor Mn availability....

  19. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Digg. Share this page from the NHLBI on Facebook. Add this link to the NHLBI to my ... Deficiency Anemia article. Updated: March 26, 2014 Twitter Facebook YouTube Google+ SITE INDEX ACCESSIBILITY PRIVACY STATEMENT FOIA ...

  20. Proximal Focal Femoral Deficiency

    OpenAIRE

    Vishal Kalia, Vibhuti

    2008-01-01

    Proximal focal femoral deficiency (PFFD) is a developmental disorder of the proximal segment of thefemur and of acetabulum resulting in shortening of the affected limb and impairment of the function. It isa spectrum of congenital osseous anomalies characterized by a deficiency in the structure of the proximalfemur. The diagnosis is often made by radiological evaluation which includes identification and descriptionof PFFD and evaluation of associated limb anomalies by plain radiographs. Contra...

  1. Iron deficiency anemia

    OpenAIRE

    Naigamwalla, Dinaz Z.; Webb, Jinelle A.; Giger, Urs

    2012-01-01

    Iron is essential to virtually all living organisms and is integral to multiple metabolic functions. The most important function is oxygen transport in hemoglobin. Iron deficiency anemia in dogs and cats is usually caused by chronic blood loss and can be discovered incidentally as animals may have adapted to the anemia. Severe iron deficiency is characterized by a microcytic, hypochromic, potentially severe anemia with a variable regenerative response. Iron metabolism and homeostasis will be ...

  2. Glucose-6-phosphatase deficiency.

    OpenAIRE

    Labrune Philippe; Gajdos Vincent; Eberschweiler Pascale; Hubert-Buron Aurélie; Petit François; Vianey-Saban Christine; Boudjemline Alix; Piraud Monique; Froissart Roseline

    2011-01-01

    Abstract Glucose-6-phosphatase deficiency (G6P deficiency), or glycogen storage disease type I (GSDI), is a group of inherited metabolic diseases, including types Ia and Ib, characterized by poor tolerance to fasting, growth retardation and hepatomegaly resulting from accumulation of glycogen and fat in the liver. Prevalence is unknown and annual incidence is around 1/100,000 births. GSDIa is the more frequent type, representing about 80% of GSDI patients. The disease commonly manifests, betw...

  3. Influence of phosphorous addition on Bi3Mo2Fe1 oxide catalysts for the oxidative dehydrogenation of 1-butene

    KAUST Repository

    Park, Jung-Hyun

    2016-01-22

    Bi3Mo2Fe1Px oxide catalysts were prepared by a co-precipitation method and the influence of phosphorous content on the catalytic performance in the oxidative dehydrogenation of 1-butene was investigated. The addition of phosphorous up to 0.4mole ratio to Bi3Mo2Fe1 oxide catalyst led to an increase in the catalytic performance; however, a higher phosphorous content (above P=0.4) led to a decrease of conversion. Of the tested catalysts, Bi3Mo2Fe1P0.4 oxide catalyst exhibited the highest catalytic performance. Characterization results showed that the catalytic performance was related to the quantity of a π-allylic intermediate, facile desorption behavior of adsorbed intermediates and ability for re-oxidation of catalysts. © 2015 Korean Institute of Chemical Engineers, Seoul, Korea

  4. Novel mesoporous mixed Nb-M (M = V, Mo, and Sb) oxides for oxidative dehydrogenation of propane.

    Science.gov (United States)

    Yuan, Li; Bhatt, Salil; Beaucage, Gregory; Guliants, Vadim V; Mamedov, Sergey; Soman, Rajiv S

    2005-12-15

    Novel thermally stable mesoporous mixed metal Nb-M (M = V, Mo and Sb) oxides were synthesized in the presence of a nonionic Pluronic P123 surfactant. These oxides displayed promising pore structures and chemical compositions for selective oxidative functionalization of propane: high surface areas (up to 200 m2/g), large pore sizes (5-14 nm), and high pore volumes (up to 0.46 cm3/g). The oxidative dehydrogenation of propane to propylene over mesoporous mixed metal Nb-M oxides employed as a probe reaction suggested that the M component was dispersed as the molecular surface species and also formed a solid solution with NbOx in the inorganic walls of these mesoporous mixed metal oxides.

  5. Silylesterification of oxidized multi-wall carbon nanotubes by catalyzed dehydrogenative cross-coupling between carboxylic and hydrosilane functions

    Science.gov (United States)

    Seffer, J.-F.; Detriche, S.; Nagy, J. B.; Delhalle, J.; Mekhalif, Z.

    2014-06-01

    Surface modification of oxidized carbon nanotubes (O-CNTs) with silicon based anchoring groups (R-SiR3) is a relatively uncommon approach of the CNTs functionalization. Hydrosilane derivatives constitute an attractive subclass of compounds for silanization reactions on the CNTs surface. In this work, we report on the ZnCl2 catalytically controlled reaction (hydrosilane dehydrogenative cross-coupling, DHCC) of fluorinated hydrosilane probes with the carboxylic functions present on the surface of oxidized multi-wall carbon nanotubes. Carbon nanotubes functionalized with essentially alcohol groups are also used to compare the selectivity of zinc chloride toward carboxylic groups. To assess the efficiency of functionalization, X-ray Photoelectron Spectroscopy is used to determine the qualitative and quantitative composition of the different samples. Solubility tests on the oxidized and silanized MWNTs are also carried out in the framework of the Hansen Solubility Parameters (HSP) theory to apprehend at another scale the effect of DHCC.

  6. Silylesterification of oxidized multi-wall carbon nanotubes by catalyzed dehydrogenative cross-coupling between carboxylic and hydrosilane functions

    Energy Technology Data Exchange (ETDEWEB)

    Seffer, J.-F., E-mail: jean-francois.seffer@unamur.be; Detriche, S.; Nagy, J.B.; Delhalle, J.; Mekhalif, Z.

    2014-06-01

    Surface modification of oxidized carbon nanotubes (O-CNTs) with silicon based anchoring groups (R-SiR{sup ′}{sub 3}) is a relatively uncommon approach of the CNTs functionalization. Hydrosilane derivatives constitute an attractive subclass of compounds for silanization reactions on the CNTs surface. In this work, we report on the ZnCl{sub 2} catalytically controlled reaction (hydrosilane dehydrogenative cross-coupling, DHCC) of fluorinated hydrosilane probes with the carboxylic functions present on the surface of oxidized multi-wall carbon nanotubes. Carbon nanotubes functionalized with essentially alcohol groups are also used to compare the selectivity of zinc chloride toward carboxylic groups. To assess the efficiency of functionalization, X-ray Photoelectron Spectroscopy is used to determine the qualitative and quantitative composition of the different samples. Solubility tests on the oxidized and silanized MWNTs are also carried out in the framework of the Hansen Solubility Parameters (HSP) theory to apprehend at another scale the effect of DHCC.

  7. A Moessbauer spectroscopic study on the action of Ce in the catalyst for dehydrogenation of etylbenzene to styrene

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Keyu, E-mail: keyujiang@126.com [East China Normal University, Department of Physics (China); Fan Qin; Chen Tong; Miao Changxi [Shanghai Research Institute of Petrochemical Technology, SINOPEC (China); Zhao Zhenji; Yang Xielong [East China Normal University, Department of Physics (China)

    2012-03-15

    Two series of Fe-K catalysts for dehydrogenation of ethylbenzene to styrene were prepared with different amounts and different compounds of the additional element Ce. Moessbauer spectroscopy has been used to determine the Fe compound in the catalyst and to investigate the effect of Ce. The catalytic properties of the catalysts have also been measured. The results show that the element Ce in the catalyst is favorable to form the predecessor of the catalytic active phase, the compound KFe{sub 11}O{sub 17} and that the optimal percentage of CeO{sub 2} is 8%{approx}15% in the catalyst which is favorable to the formation of KFe{sub 11}O{sub 17} and to get better catalytic properties.

  8. Dehydrogenative Synthesis of Imines from Alcohols and Amines Catalyzed by a Ruthenium N-Heterocyclic Carbene Complex

    DEFF Research Database (Denmark)

    Maggi, Agnese; Madsen, Robert

    2012-01-01

    be applied to a variety of primary alcohols and amines and can be combined with a subsequent addition reaction. A deuterium labeling experiment indicates that the catalytically active species is a ruthenium dihydride. The reaction is believed to proceed by initial dehydrogenation of the alcohol......A new method for the direct synthesis of imines from alcohols and amines is described where hydrogen gas is liberated. The reaction is catalyzed by the ruthenium N-heterocyclic carbene complex [RuCl2(IiPr)(p-cymene)] in the presence of the ligand DABCO and molecular sieves. The imination can...... to the aldehyde, which stays coordinated to ruthenium. Nucleophilic attack of the amine affords the hemiaminal, which is released from ruthenium and converted into the imine....

  9. Catalytic synthesis of 2-methylpyrazine over Cr-promoted copper based catalyst via a cyclo-dehydrogenation reaction route

    Indian Academy of Sciences (India)

    Fangli Jing; Yuanyuan Zhang; Shizhong Luo; Wei Chu; Hui Zhang; Xinyu Shi

    2010-07-01

    The cyclo-dehydrogenation of ethylene diamine and propylene glycol to 2-methylpyrazine was performed under the atmospheric conditions at 380°C. The Cr-promoted Cu-Zn/Al2O3 catalysts were prepared by impregnation method and characterized by ICP-AES, N2 adsorption/desorption, XRD, XPS, N2O chemisorption, TPR and NH3-TPD techniques. The amorphous chromium species existing in Cu-Zn-Cr/Al2O3 catalyst enhanced the dispersion of active component Cu, promoted the reduction of catalyst. Furthermore, the catalytic performance was significantly improved. The acidity of the catalyst played an important role in increasing the 2-MP selectivity. To optimize the reaction parameters, influences of different chromium content, reaction temperature, liquid hourly space velocity (LHSV), reactants molar ratio and time on stream on the product pattern were studied. The results demonstrated that addition of chromium promoter revealed satisfying catalytic activity, stability and selectivity of 2-methylpyrazine.

  10. Preparation and characterization of Ni-Zr-O nanoparticles and its catalytic behavior for ethane oxidative dehydrogenation

    Science.gov (United States)

    Wu, Ying; Gao, Jing; He, Yiming; Wu, Tinghua

    2012-03-01

    Ni-Zr-O nanoparticles with various Zr contents were prepared by a modified sol-gel method and characterized by X-ray diffraction (XRD), scanning/high-resolution transmission electron microscope (SEM/HRTEM), BET surface area analysis, H2 temperature-programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS) and O2 temperature-programmed desorption (O2-TPD). The oxidative dehydrogenation of ethane (ODHE) to ethylene was applied to evaluate catalytic performance of the samples. The results show that the doping of Zr affected the cell parameter and the chemical environment of the catalysts, indicating the existence of strong interaction between Ni and Zr. The interaction plays an important role in the lessened reducibility and the distribution of adsorbed oxygen species, consequently influence their catalytic performance. The best yield to ethylene was obtained over the 10% Ni-Zr-O catalyst with 60% ethane conversion and 66% ethylene selectivity.

  11. Mathematical Modeling and Simulation of the Dehydrogenation of Ethyl Benzene to Form Styrene Using Steady-State Fixed Bed Reactor

    Directory of Open Access Journals (Sweden)

    Zaidon M. Shakoor

    2013-05-01

    Full Text Available In this research, two models are developed to simulate the steady state fixed bed reactor used for styrene production by ethylbenzene dehydrogenation. The first is one-dimensional model, considered axial gradient only while the second is two-dimensional model considered axial and radial gradients for same variables.The developed mathematical models consisted of nonlinear simultaneous equations in multiple dependent variables. A complete description of the reactor bed involves partial, ordinary differential and algebraic equations (PDEs, ODEs and AEs describing the temperatures, concentrations and pressure drop across the reactor was given. The model equations are solved by finite differences method. The reactor models were coded with Mat lab 6.5 program and various numerical techniques were used to obtain the desired solution.The simulation data for both models were validated with industrial reactor results with a very good concordance.

  12. Cluster-derived Ir-Sn/SiO2 catalysts for the catalytic dehydrogenation of propane: A spectroscopic study

    KAUST Repository

    Gallo, Alessandro

    2013-01-01

    Ir-Sn bimetallic silica-based materials have been prepared via deposition of the molecular organometallic clusters (NEt4)2[Ir 4(CO)10(SnCl3)2] and NEt 4[Ir6(CO)15(SnCl3)] or via deposition of Sn organometallic precursor Sn(n-C4H9) 4 onto pre-formed Ir metal particles. These solids possess promising properties, in terms of selectivity, as catalysts for propane dehydrogenation to propene. Detailed CO-adsorption DRIFTS, XANES and EXAFS characterization studies have been performed on these systems in order to compare the structural and electronic evolution of systems in relation to the nature of the Ir-Sn bonds present in the precursor compounds and to propose a structural model of the Ir-Sn species present at the silica surface of the final catalyst. © 2013 The Royal Society of Chemistry.

  13. Oxidative dehydrogenation of ethane over RE-NiO (RE=La, Nd, Sm, Gd)catalysts

    Institute of Scientific and Technical Information of China (English)

    ZHOU Qin; ZHOU Dishan; WU Ying; WU Tinghua

    2013-01-01

    RE-NiO (RE=La,Nd,Sm,Gd) catalysts were prepared by a modified sol-gel method and characterized by X-ray diffraction (XRD),transmission electron microscopy (TEM),BET surface area analysis,H2 temperature-programmed reduction (H2-TPR),and O2 temperature-programmed desorption (O2-TPD).The oxidative dehydrogenation of ethane (ODHE) to ethylene was applied to evaluate catalytic performance of the samples.The results showed that the doping of RE affected the physicochemical properties of the catalysts.The strong interaction between Gd and NiO played an important role in the lessened reducibility and the distribution of adsorbed oxygen species,consequently influenced the catalytic performance.The best yield to ethylene of 29% was obtained over the Gd-NiO catalyst with an ethane conversion of 56%.

  14. Characterization of Industrial Pt-Sn/Al2O3 Catalyst and Transient Product Formations during Propane Dehydrogenation

    Directory of Open Access Journals (Sweden)

    Kah Sing Ho

    2013-06-01

    Full Text Available The major problem plaguing propane dehydrogenation process is the coke formation on the Pt-Sn/Al2O3 catalyst which leads to catalyst deactivation. Due to information paucity, the physicochemical characteristics of the commercially obtained regenerated Pt-Sn/Al2O3 catalyst (operated in moving bed reactor and coke formation at different temperatures of reaction were discussed. The physicochemical characterization of regenerated catalyst gave a BET surface area of 104.0 m2/g with graphitic carbon content of 8.0% indicative of incomplete carbon gasification during the industrial propylene production. Effect of temperatures on coke formation was identified by studying the product yield via temperature-programmed reaction carried out at 500oC, 600oC and 700oC. It was found that ethylene was precursor to carbon laydown while propylene tends to crack into methane. Post reaction, the spent catalyst possessed relatively lower surface area and pore radius whilst exhibited higher carbon content (31.80% at 700oC compared to the regenerated catalyst. Significantly, current studies also found that higher reaction temperatures favoured the coke formation. Consequently, the propylene yield has decreased with reaction temperature. © 2013 BCREC UNDIP. All rights reservedReceived: 10th March 2013; Revised: 28th April 2013; Accepted: 6th May 2013[How to Cite: Kah, S.H., Joanna Jo, E.C., Sim, Y.C., Chin, K.C. (2013. Characterization of Industrial Pt-Sn/Al2O3 Catalyst and Transient Product Formations during Propane Dehydrogenation. Bulletin of Chemical Reaction Engineering & Catalysis, 8 (1: 77-82. (doi:10.9767/bcrec.8.1.4569.77-82][Permalink/DOI: http://dx.doi.org/10.9767/bcrec.8.1.4569.77-82] | View in  |

  15. Kinetics of propane dehydrogenation in CO{sub 2} presence over chromium and gallium oxide catalysts based on MCM-41

    Energy Technology Data Exchange (ETDEWEB)

    Lapidus, A.L.; Gaidai, N.A.; Nekrasov, N.V.; Agafonov, A.Yu.; Botavina, M.A. [Russian Academy of Sciences, Moscow (Russian Federation). N.D. Zelinsky Institute of Organic Chemistry

    2012-07-01

    Chromium and gallium catalysts based on MCM-41 with different contents of active metals were prepared and tested for propane dehydrogenation in the presence and absence of CO{sub 2}. It was shown that CO{sub 2} increased the yield of propene and decreased considerably the rate of deactivation of Cr/MCM-41 and decreased propene yield and slightly improved the stability of Ga/MCM-41. The study of kinetics in unstationary and stationary fields showed that the decrease of propene yield was connected with strong competitive adsorption of CO{sub 2} over Ga-catalysts what presented difficulties for propane adsorption. The formation of cracking products was decreased in CO{sub 2} presence over both catalysts. The catalysts were differed by the adsorption capacity of the reaction components: C{sub 3}H{sub 6} was tied more strongly than CO{sub 2} over Cr-catalysts, CO{sub 2} was tied more firmly than C{sub 3}H{sub 6} over Ga-catalysts. Kinetic data showed that of H{sub 2} was bounded with the surface of Ga-catalysts very firmly, reverse watergas shift reaction proceeded in considerably more extent over Cr-catalysts than over Gaones. CO{sub 2} took active participation in oxidation of coke and surface of Cr-catalysts. The positive role of CO{sub 2} in propane dehydrogenation over Ga-catalysts consisted in a decrease of coke and cracking products. Kinetic equations and step-schemes for propene and cracking products formation were proposed. (orig.)

  16. Synergic catalytic effect of Ti hydride and Nb nanoparticles for improving hydrogenation and dehydrogenation kinetics of Mg-based nanocomposite

    Directory of Open Access Journals (Sweden)

    Xiujuan Ma

    2017-02-01

    Full Text Available The Mg-9.3 wt% (TiH1.971-TiH−0.7 wt% Nb nanocomposite has been synthesized by hydrogen plasma-metal reaction (HPMR approach to enhance the hydrogen sorption kinetics of Mg at moderate temperatures by providing nanosizing effect of increasing H “diffusion channels” and adding transition metallic catalysts. The Mg nanoparticles (NPs were in hexagonal shape range from 50 to 350 nm and the average size of the NPs was 177 nm. The small spherical TiH1.971, TiH and Nb NPs of about 25 nm uniformly decorated on the surface of the big Mg NPs. The Mg-TiH1.971-TiH-Nb nanocomposite could quickly absorb 5.6 wt% H2 within 5 min at 573 K and 4.5 wt% H2 within 5 min at 523 K, whereas the pure Mg prepared by HPMR could only absorb 4 and 1.5 wt% H2 at the same temperatures. TiH1.971, TiH and Nb NPs transformed into TiH2 and NbH during hydrogenation and recovered after dehydrogenation process. The apparent activation energies of the nanocomposite for hydrogenation and dehydrogenation were 45.0 and 50.7 kJ mol−1, which are much smaller than those of pure Mg NPs, 123.8 and 127.7 kJ mol−1. The improved sorption kinetics of the Mg-based nanocomposite at moderate temperatures and the small activation energy can be interpreted by the nanostructure of Mg and the synergic catalytic effects of Ti hydrides and Nb NPs.

  17. Sn surface-enriched Pt-Sn bimetallic nanoparticles as a selective and stable catalyst for propane dehydrogenation

    KAUST Repository

    Zhu, Haibo

    2014-12-01

    A new one pot, surfactant-free, synthetic route based on the surface organometallic chemistry (SOMC) concept has been developed for the synthesis of Sn surface-enriched Pt-Sn nanoparticles. Bu3SnH selectively reacts with [Pt]-H formed in situ at the surface of Pt nanoparticles, Pt NPs, obtained by reduction of K2PtCl4 by LiB(C2H5)3H. Chemical analysis, 1H MAS and 13C CP/MAS solid-state NMR as well as two-dimensional double-quantum (DQ) and triple-quantum (TQ) experiments show that organo-tin moieties Sn(n-C4H9) are chemically linked to the surface of Pt NPs to produce, in fine, after removal of most of the n-butyl fragment, bimetallic Pt-Sn nanoparticles. The Sn(n-CH2CH2CH2CH3) groups remaining at the surface are believed to stabilize the as-synthesized Pt-Sn NPs, enabling the bimetallic NPs to be well dispersed in THF. Additionally, the Pt-Sn nanoparticles can be supported on MgAl2O4 during the synthesis of the nanoparticles. Some of the Pt-Sn/MgAl2O4 catalyst thus prepared exhibits high activity in PROX of CO and an extremely high selectivity and stability in propane dehydrogenation to propylene. The enhanced activity in propane dehydrogenation is associated with the high concentration of inactive Sn at the surface of Pt nanoparticles which ”isolates” the active Pt atoms. This conclusion is confirmed by XRD, NMR, TEM, and XPS analysis.

  18. Lipid-storage myopathy and respiratory insufficiency due to ETFQO mutations in a patient with late-onset multiple acyl-CoA dehydrogenation deficiency

    DEFF Research Database (Denmark)

    Olsen, Rikke Katrine Jentoft; Pourfarzam, M; Morris, A A M;

    2004-01-01

    response to treatment, she developed respiratory insufficiency at age 14 years and has required long-term overnight ventilation. Thus, MADD is one of the few conditions that can cause a myopathy with weakness of the respiratory muscles out of proportion to the limb muscles. Udgivelsesdato: 2004-null...

  19. Lipid-storage myopathy and respiratory insufficiency due to ETFQO mutations in a patient with late-onset multiple acyl-CoA dehydrogenation deficiency

    DEFF Research Database (Denmark)

    Olsen, R K J; Pourfarzam, M; Morris, A A M;

    2004-01-01

    response to treatment, she developed respiratory insufficiency at age 14 years and has required long-term overnight ventilation. Thus, MADD is one of the few conditions that can cause a myopathy with weakness of the respiratory muscles out of proportion to the limb muscles....

  20. Iron deficiency anaemia.

    Science.gov (United States)

    Lopez, Anthony; Cacoub, Patrice; Macdougall, Iain C; Peyrin-Biroulet, Laurent

    2016-02-27

    Anaemia affects roughly a third of the world's population; half the cases are due to iron deficiency. It is a major and global public health problem that affects maternal and child mortality, physical performance, and referral to health-care professionals. Children aged 0-5 years, women of childbearing age, and pregnant women are particularly at risk. Several chronic diseases are frequently associated with iron deficiency anaemia--notably chronic kidney disease, chronic heart failure, cancer, and inflammatory bowel disease. Measurement of serum ferritin, transferrin saturation, serum soluble transferrin receptors, and the serum soluble transferrin receptors-ferritin index are more accurate than classic red cell indices in the diagnosis of iron deficiency anaemia. In addition to the search for and treatment of the cause of iron deficiency, treatment strategies encompass prevention, including food fortification and iron supplementation. Oral iron is usually recommended as first-line therapy, but the most recent intravenous iron formulations, which have been available for nearly a decade, seem to replenish iron stores safely and effectively. Hepcidin has a key role in iron homoeostasis and could be a future diagnostic and therapeutic target. In this Seminar, we discuss the clinical presentation, epidemiology, pathophysiology, diagnosis, and acute management of iron deficiency anaemia, and outstanding research questions for treatment.

  1. [Vitamin deficiencies and hypervitaminosis].

    Science.gov (United States)

    Mino, M

    1999-10-01

    There have recently been very few deficiencies with respect to fat soluble and water soluble vitamins in Japan All-trans-retinoic acid as induction or maintenance treatment improves disease free and overall survival against acute promyelocytic leukemia. In the isolated vitamin E deficiencies gene mutation has been cleared for alpha-tocopherol transferprotein. Recently, a relation of nutritional vitamin K intake and senile osteoporosis in women was epidemiologically demonstrated on a prospective study. Thiamin was yet noticed as development of deficiency in alcoholism, while the importance of supplemental folic acid during pregnancy has become especially clear in light of studies showing that folic acid supplements reduce the risk of neural tube defects in the fetus. With respect to hypervitaminosis, the Council for Responsible Nutrition (CRN), USA, has established safe intakes by identifying the NOAEL (No Observed Adverse Effect Level) and LOAEL (Lowest Observed Adverse Effect Level). Summaries of NOAEL and LOAEL for individual vitamins were shown.

  2. Antepartum Ornithine Transcarbamylase Deficiency

    Directory of Open Access Journals (Sweden)

    Hitoshi Nakajima

    2014-11-01

    Full Text Available Ornithine transcarbamylase deficiency (OTCD is the most common type urea cycle enzyme deficiencies. This syndrome results from a deficiency of the mitochondrial enzyme ornithine transcarbamylase, which catalyzes the conversion of ornithine and carbamoyl phosphate to citrullin. Our case was a 28-year-old female diagnosed with OTCD following neurocognitive deficit during her first pregnancy. Although hyperammonemia was suspected as the cause of the patient's mental changes, there was no evidence of chronic liver disease. Plasma amino acid and urine organic acid analysis revealed OTCD. After combined modality treatment with arginine, sodium benzoate and hemodialysis, the patient's plasma ammonia level stabilized and her mental status returned to normal. At last she recovered without any damage left.

  3. Mortality and GH deficiency

    DEFF Research Database (Denmark)

    Stochholm, Kirstine; Gravholt, Claus Højbjerg; Laursen, Torben;

    2007-01-01

    OBJECTIVE: To estimate the mortality in Denmark in patients suffering from GH deficiency (GHD). DESIGN: Mortality was analyzed in 1794 GHD patients and 8014 controls matched on age and gender. All records in GHD patients were studied and additional morbidity noted. Patients were divided into chil......OBJECTIVE: To estimate the mortality in Denmark in patients suffering from GH deficiency (GHD). DESIGN: Mortality was analyzed in 1794 GHD patients and 8014 controls matched on age and gender. All records in GHD patients were studied and additional morbidity noted. Patients were divided...

  4. DH-2型脱氢催化剂的使用及维护%Use and Maintenance of DH-2 Dehydrogenation Catalyst

    Institute of Scientific and Technical Information of China (English)

    任玉兵

    2014-01-01

    介绍CO2汽提法尿素装置应用DH‐2型脱氢催化剂的情况,包括脱氢原理、工艺操作指标、催化剂装填、运行中的注意事项、影响其活性的因素,以及异常情况的处理等。%Describe the use of the DH‐2 dehydrogenation catalyst in the CO2 stripping urea plant , w hich including the dehydrogenation mechanism , the process operation index , the catalyst loading , the operation precautions , the catalyst activity affecting factor and the abnormal situation handling , etc .

  5. Influence of vanadium oxidation states on the performance of V-Mg-Al mixed-oxide catalysts for the oxidative dehydrogenation of propane

    Energy Technology Data Exchange (ETDEWEB)

    Schacht, L. [IPN, Escuela Superior de Fisica y Matematicas, Departamento de Ciencia de Materiales, Av. IPN s/n, Edificio 9, Col. Lindavista, 07738 Mexico D. F. (Mexico); Navarrete, J.; Schacht, P.; Ramirez, M. A., E-mail: pschacha@imp.m [Instituto Mexicano del Petroleo, Programa de Ingenieria Molecular, Eje Central Lazaro Cardenas No. 152, 07730 Mexico D. F. (Mexico)

    2010-07-01

    V-Mg-Al mixed-oxide catalysts for oxidative dehydrogenation of propane were prepared by thermal decomposition of Mg-Al-layered double hydroxides with vanadium interlayer doping. The obtained catalysts were tested for the oxidative dehydrogenation of propane, obtaining good results in catalytic activity (conversion 16.55 % and selectivity 99.97 %) Results indicated that catalytic performance of these materials depends on how vanadium is integrated in the layered structure, which is determined by the Mg/Al ratio. Vanadium interlayer doping modifies the oxidation state of vanadium and consequently catalytic properties. Surface properties were studied by X-ray photoelectron spectroscopic and diffuse reflectance, UV-visible spectroscopy, and temperature programmed reduction. The analyses provided information about the oxidation state, before and after the reaction. From these results, it is suggested that selectivity to propylene and catalytic activity depend mainly of vanadium oxidation state. (Author)

  6. Inlfuence of the Alkali Treatment of HZSM-5 Zeolite on Catalytic Performance of PtSn-Based Catalyst for Propane Dehydrogenation

    Institute of Scientific and Technical Information of China (English)

    Huang Li; Zhou Shijian; Zhou Yuming; Zhang Yiwei; Xu Jun; Wang Li

    2013-01-01

    The porous material ATZ with micro-mesopore hierarchical porosity was prepared by alkali treatment of parent HZSM-5 zeolite and applied for propane dehydrogenation. The zeolite samples were characterized by XRD, N2-physisorption, and NH3-TPD analysis. The results showed that the alkali treatment can modify the physicochemical prop-erties of HZSM-5 zeolite. In this case, the porous material ATZ showed larger external surface area with less acid sites as compared to the HZSM-5 zeolite. It was found out that the alkali treatment of HZSM-5 zeolite could promote the catalytic performance of PtSn/ATZ catalyst. The possible reason was ascribed to the low acidity of ATZ. Furthermore, the presence of mesopores could reduce the carbon deposits on the metallic surface, which was also favorable for the dehydrogenation reaction.

  7. Dehydrogenative [2 + 2 + 1] Heteroannulation Using a Methyl Group as a One-Carbon Unit: Access to Pyrazolo[3,4-c]quinolines.

    Science.gov (United States)

    Deng, Guo-Bo; Li, Hai-Bing; Yang, Xu-Heng; Song, Ren-Jie; Hu, Ming; Li, Jin-Heng

    2016-05-06

    A practical and straightforward access to pyrazolo[3,4-c]quinolines by molecular sieve mediated dehydrogenative [2 + 2 + 1] heteroannulation of N-(o-alkenylaryl)imines with aryldiazonium salts is described using a sp(3)-hybrid carbon atom as a one-carbon unit. The reaction enables the formation of three new chemical bonds, a C-C bond and two C-N bonds, in a single reaction and features simple operation and excellent functional group tolerance.

  8. Dehydrogenation kinetics, reversibility, and reaction mechanisms of reversible hydrogen storage material based on nanoconfined MgH2-NaAlH4

    Science.gov (United States)

    Plerdsranoy, Praphatsorn; Meethom, Sukanya; Utke, Rapee

    2015-12-01

    Studies of dehydrogenation kinetics, reversibility, and reaction mechanisms during de/rehydrogenation of nanoconfined MgH2-NaAlH4 into carbon aerogel scaffold (CAS) for reversible hydrogen storage material are for the first time proposed. Two different MgH2:NaAlH4 molar ratios (1:1 and 2:1) of hydride composite are melt infiltrated into CAS under 1:1 (CAS:hydride composite) weight ratio. Successful nanoconfinement is confirmed by N2 adsorption-desorption. Multiple-step dehydrogenation of milled samples is reduced to two-step reaction due to nanoconfinement. Peak temperatures corresponding to main dehydrogenation of nanoconfined samples significantly reduce as compared with those of milled samples, i.e., ∆T=up to 50 and 34 °C for nanoconfined sample with 1:1 and 2:1 (MgH2:NaAlH4) molar ratios, respectively. Hydrogen content released (the 1st cycle) and reproduced (the 2nd, 3rd, and 4th cycles) of nanoconfined samples enhance up to 80% and 68% with respect to theoretical hydrogen storage capacity, respectively, while those of milled samples are 71% and 38%, respectively. Remarkable hydrogen content reproduced after nanoconfinement is due to the fact that metallic Al obtained after dehydrogenation (T=300 °C under vacuum) of nanoconfined samples prefer to react with MgH2 and produces Al12Mg17, favorable for reversibility of MgH2-NaAlH4 system, whereas that of milled samples stays in the form of unreacted Al under the same temperature and pressure condition.

  9. Ceria-Based Mixed Oxide Supported Nano-Gold as an Efficient and Durable Heterogeneous Catalyst for Oxidative Dehydrogenation of Amines to Imines Using Molecular Oxygen

    Directory of Open Access Journals (Sweden)

    Bashir Ahmad Dar

    2012-06-01

    Full Text Available The present work is intended to determine the catalytic activity of Mixed Oxide supported gold for aerobic oxidative dehydrogenation of amines to imines using Ceria as a main constituent of the each support. The model catalysts Au/CeO2:TiO2 Au/CeO2:SiO2, Au/CeO2:ZrO2 and Au/CeO2:Al2Os were prepared by deposition co-precipitation method and deposition of gold was determined by EDEX analysis. The supported nano-gold catalyzes the dehydrogenation of secondary amines to imines without loss of activity. On recycling good amount of product yield is obtained. Oxidation of secondary amines to imines is carried at 100˚C and almost 90 % conversion was obtained with >99% selectivity. © 2012 BCREC UNDIP. All rights reservedReceived: 26th December 2011; Revised: 7th June 2012; Accepted: 13rd June 2012[How to Cite: B.A. Dar, M. Sharma, B. Singh. (2012. Ceria-Based Mixed Oxide Supported Nano-Gold as an Efficient and Durable Heterogeneous Catalyst for Oxidative Dehydrogenation of Amines to Imines Using Molecular Oxygen. Bulletin of Chemical Reaction Engineering & Catalysis, 7(1: 79-84.  doi:10.9767/bcrec.7.1.1257.79-84][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.7.1.1257.79-84 ] | View in 

  10. Reaction of niobium and tantalum neutral clusters with low pressure, unsaturated hydrocarbons in a pickup cell: From dehydrogenation to Met-Car formation

    Science.gov (United States)

    He, S.-G.; Xie, Y.; Dong, F.; Bernstein, E. R.

    2006-10-01

    Neutral niobium and tantalum clusters (Nbn and Tan) are generated by laser ablation and supersonic expansion into a vacuum and are reacted in a pickup cell with various low pressure (˜1mTorr) unsaturated hydrocarbons (acetylene, ethylene, propylene, 1-butene, 1,3-butadiene, benzene, and toluene) under nearly single collision conditions. The bare metal clusters and their reaction products are ionized by a 193nm laser and detected by a time of flight mass spectrometer. Partially and fully dehydrogenated products are observed for small (n⩽m) and large (n⩾m) neutral metal clusters, respectively, with m ranging from 2 to 5 depending on the particular hydrocarbon. In addition to primary, single collision products, sequential addition products that are usually fully dehydrogenated are also observed. With toluene used as the reactant gas, carbon loss products are observed, among which Nb8C12 and Ta8C12 are particularly abundant, indicating that the Met-Car molecule M8C12 can be formed from the neutral metal cluster upon two collisions with toluene molecules. The dehydrogenation results for low pressure reactions are compared with those available from previous studies employing flow tube (high pressure) reactors. Low pressure and high pressure cluster ion reactions are also compared with the present neutral metal cluster reactions. Reactions of unsaturated hydrocarbons and metal surfaces are discussed in terms of the present neutral cluster results.

  11. Dehydrogenation kinetics of pure and nickel-doped magnesium hydride investigated by in situ time-resolved powder X-ray diffraction

    DEFF Research Database (Denmark)

    Jensen, T.R.; Andreasen, A.; Vegge, Tejs;

    2006-01-01

    conditions. A quartz capillary cell allowed the in situ study of gas/solid reactions. Three phases were identified: Mg, MgH2 and MgO and their phase fractions were extracted by Rietveld refinement or integration of selected reflections from each phase. Dehydrogenation curves were constructed and analysed...... by the Johnson-Mehi-Avrami formalism in order to derive rate constants at different temperatures. The apparent activation energies for dehydrogenation of pure and Ni-doped magnesium hydride were E-A approximate to 300 and 250 kJ/mol, respectively. Differential scanning calorimetry gave, E-A = 270 k......J/mol for dehydrogenation of the Ni-doped sample. The relatively high activation energies are due to MgO surface layers, retarding the diffusion of hydrogen (H-2) out of MgH2/Mg. The observed difference in E-A of ca. 50 kJ/moI is likely due to the catalytic effect of Ni on the recombination of H atoms to H-2 molecules...

  12. Ultraviolet-Visible (UV-Vis) Microspectroscopic System Designed for the In Situ Characterization of the Dehydrogenation Reaction Over Platinum Supported Catalytic Microchannel Reactor.

    Science.gov (United States)

    Suarnaba, Emee Grace Tabares; Lee, Yi Fuan; Yamada, Hiroshi; Tagawa, Tomohiko

    2016-11-01

    An ultraviolet visible (UV-Vis) microspectroscopic system was designed for the in situ characterization of the activity of the silica supported platinum (Pt) catalyst toward the dehydrogenation of 1-methyl-1,4-cyclohexadiene carried out in a custom-designed catalytic microreactor cell. The in situ catalytic microreactor cell (ICMC) with inlet/outlet ports was prepared using quartz cover as the optical window to facilitate UV-Vis observation. A fabricated thermometric stage was adapted to the UV-Vis microspectrophotometer to control the reaction temperature inside the ICMC. The spectra were collected by focusing the UV-Vis beam on a 30 × 30 µm area at the center of ICMC. At 393 K, the sequential measurement of the spectra recorded during the reaction exhibited a broad absorption peak with maximum absorbance at 260 nm that is characteristic for gaseous toluene. This result indicates that the silica supported Pt catalyst is active towards the dehydrogenation of 1-methyl-1,4-cyclohexadiene at the given experimental conditions. The onset of coke formation was also detected based on the appearance of absorption bands at 300 nm. The UV-Vis microspectroscopic system developed can be used further in studying the mechanism of the dehydrogenation reaction.

  13. Aqueous solution synthesis of Pt-M (M = Fe, Co, Ni) bimetallic nanoparticles and their catalysis for the hydrolytic dehydrogenation of ammonia borane.

    Science.gov (United States)

    Wang, Shuai; Zhang, Duo; Ma, Yanyun; Zhang, Hui; Gao, Jing; Nie, Yuting; Sun, Xuhui

    2014-08-13

    Platinum-based bimetallic nanocatalysts have attracted much attention due to their high-efficiency catalytic performance in energy-related applications such as fuel cell and hydrogen storage, for example, the hydrolytic dehydrogenation of ammonia borane (AB). In this work, a simple and green method has been demonstrated to successfully prepare Pt-M (M = Fe, Co, Ni) NPs with tunable composition (nominal Pt/M atomic ratios of 4:1, 1:1, and 1:4) in aqueous solution under mild conditions. All Pt-M NPs with a small size of 3-5 nm show a Pt fcc structure, suggesting the bimetallic formation (alloy and/or partial core-shell), examined by transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray absorption fine structure (XAFS) analysis. The catalytic activities of Pt-M NPs in the hydrolytic dehydrogenation of AB reveal that Pt-Ni NPs with a ratio of 4:1 show the best catalytic activity and even better than that of pure Pt NPs when normalized to Pt molar amount. The Ni oxidation state in Pt-Ni NPs has been suggested to be responsible for the corresponding catalytic activity for hydrolytic dehydrogenation of AB by XAFS study. This strategy for the synthesis of Pt-M NPs is simple and environmentally benign in aqueous solution with the potential for scale-up preparation and the in situ catalytic reaction.

  14. Insights into dehydrogenative coupling of alcohols and amines catalyzed by a (PNN)-Ru(II) hydride complex: unusual metal-ligand cooperation.

    Science.gov (United States)

    Zeng, Guixiang; Li, Shuhua

    2011-11-07

    Density functional theory calculations were performed to elucidate the mechanism of dehydrogenative coupling of primary alcohols and amines mediated by a PNN-Ru(II) hydride complex (PNN = (2-(di-tert-butylphosphinomethyl)-6-(diethylaminomethyl)pyridine)). A plausible reaction pathway was proposed which contains three stages: (1) The alcohol dehydrogenation reaction to generate the aldehyde and H(2); (2) The aldehyde-amine condensation reaction to form the hemiaminal intermediate; (3) The dehydrogenation process of the hemiaminal intermediate to yield the final amide product with the liberation of H(2). The first and third stages occur via a similar pathway: (a) Proton transfer from the substrate to the PNN ligand; (b) Intramolecular rearrangement of the deprotonated substrate to form an anagostic complex; (c) Hydride transfer from the deprotonated substrate to the Ru center to yield the trans-dihydride intermediate and the aldehyde (or amide); (d) Benzylic proton migration from the PNN ligand to the metal center forming a dihydrogen complex and subsequent H(2) liberation to regenerate the catalyst. In all these steps, the metal-ligand cooperation plays an essential role. In proton transfer steps (a) and (d), the metal-ligand cooperation is achieved through the aromatization/dearomatization processes of the PNN ligand. While in steps (b) and (c), their collaboration are demonstrated by the formation of an anagostic interaction between Ru and the C-H bond and two ionic hydrogen bonds supported by the PNN ligand.

  15. Diagnosing oceanic nutrient deficiency

    Science.gov (United States)

    Moore, C. Mark

    2016-11-01

    The supply of a range of nutrient elements to surface waters is an important driver of oceanic production and the subsequent linked cycling of the nutrients and carbon. Relative deficiencies of different nutrients with respect to biological requirements, within both surface and internal water masses, can be both a key indicator and driver of the potential for these nutrients to become limiting for the production of new organic material in the upper ocean. The availability of high-quality, full-depth and global-scale datasets on the concentrations of a wide range of both macro- and micro-nutrients produced through the international GEOTRACES programme provides the potential for estimation of multi-element deficiencies at unprecedented scales. Resultant coherent large-scale patterns in diagnosed deficiency can be linked to the interacting physical-chemical-biological processes which drive upper ocean nutrient biogeochemistry. Calculations of ranked deficiencies across multiple elements further highlight important remaining uncertainties in the stoichiometric plasticity of nutrient ratios within oceanic microbial systems and caveats with regards to linkages to upper ocean nutrient limitation. This article is part of the themed issue 'Biological and climatic impacts of ocean trace element chemistry'.

  16. Factor V deficiency

    Science.gov (United States)

    ... When certain blood clotting factors are low or missing, your blood does not clot properly. Factor V deficiency is rare. It may be caused by: A defective Factor V gene passed down through families (inherited) An antibody that interferes with normal Factor ...

  17. Iodine-deficiency disorders

    NARCIS (Netherlands)

    Zimmermann, M.B.; Jooste, P.L.; Pandav, C.S.

    2008-01-01

    billion individuals worldwide have insufficient iodine intake, with those in south Asia and sub-Saharan Africa particularly affected. Iodine deficiency has many adverse effects on growth and development. These effects are due to inadequate production of thyroid hormone and are termed iodine-deficien

  18. Alpha1-antitrypsin deficiency

    DEFF Research Database (Denmark)

    Stolk, Jan; Seersholm, Niels; Kalsheker, Noor

    2006-01-01

    biennially to exchange views and research findings. The fourth biennial meeting was held in Copenhagen, Denmark, on 2-3 June 2005. This review covers the wide range of AAT deficiency-related topics that were addressed encompassing advances in genetic characterization, risk factor identification, clinical...... epidemiology, inflammatory and signalling processes, therapeutic advances, and lung imaging techniques....

  19. Sleep Deprivation and Deficiency

    Science.gov (United States)

    ... page from the NHLBI on Twitter. What Are Sleep Deprivation and Deficiency? Sleep deprivation (DEP-rih-VA-shun) is a condition that ... the following: You don't get enough sleep (sleep deprivation) You sleep at the wrong time of day ( ...

  20. Morbidity and GH deficiency

    DEFF Research Database (Denmark)

    Stochholm, Kirstine; Laursen, Torben; Green, Anders;

    2008-01-01

    OBJECTIVE: To estimate morbidity in Denmark in all patients with GH deficiency (GHD). DESIGN: Morbidity was analyzed in 1794 GHD patients and 8014 controls matched on age and gender. All records in the GHD patients were studied and additional morbidity noted. Diagnoses and dates of admissions were...

  1. Glucose-6-phosphate dehydrogenase deficiency

    Science.gov (United States)

    ... medlineplus.gov/ency/article/000528.htm Glucose-6-phosphate dehydrogenase deficiency To use the sharing features on this page, please enable JavaScript. Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a condition in which ...

  2. Growth Hormone Deficiency in Children

    Science.gov (United States)

    ... c m y one in Children What is growth hormone deficiency? Growth hormone deficiency (GHD) is a rare condition in which the body does not make enough growth hormone (GH). GH is made by the pituitary gland, ...

  3. Iron deficiency and cognitive functions

    Directory of Open Access Journals (Sweden)

    Jáuregui-Lobera I

    2014-11-01

    Full Text Available Ignacio Jáuregui-Lobera Department of Nutrition and Bromatology, Pablo de Olavide University, Seville, Spain Abstract: Micronutrient deficiencies, especially those related to iodine and iron, are linked to different cognitive impairments, as well as to potential long-term behavioral changes. Among the cognitive impairments caused by iron deficiency, those referring to attention span, intelligence, and sensory perception functions are mainly cited, as well as those associated with emotions and behavior, often directly related to the presence of iron deficiency anemia. In addition, iron deficiency without anemia may cause cognitive disturbances. At present, the prevalence of iron deficiency and iron deficiency anemia is 2%–6% among European children. Given the importance of iron deficiency relative to proper cognitive development and the alterations that can persist through adulthood as a result of this deficiency, the objective of this study was to review the current state of knowledge about this health problem. The relevance of iron deficiency and iron deficiency anemia, the distinction between the cognitive consequences of iron deficiency and those affecting specifically cognitive development, and the debate about the utility of iron supplements are the most relevant and controversial topics. Despite there being methodological differences among studies, there is some evidence that iron supplementation improves cognitive functions. Nevertheless, this must be confirmed by means of adequate follow-up studies among different groups. Keywords: iron deficiency, anemia, cognitive functions, supplementation

  4. Effects of CeO2 Support Facets on VOx/CeO2 Catalysts in Oxidative Dehydrogenation of Methanol

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yan; Wei, Zhehao; Gao, Feng; Kovarik, Libor; Peden, Charles HF; Wang, Yong

    2014-05-13

    CeO2 supports with dominating facets, i.e., low index (100), (110) and (111) facets, are prepared. The facet effects on the structure and catalytic performance of supported vanadium oxide catalysts are investigated using oxidative dehydrogenation of methanol as a model reaction. In the presence of mixed facets, Infrared and Raman characterizations demonstrate that surface vanadia species preferentially deposit on CeO2 (100) facets, presumably because of its higher surface energy. At the same surface vanadium densities, VOx species on (100) facets show better dispersion, followed by (110) and (111) facets. The VOx species on CeO2 nanorods with (110) and (100) facets display higher activity and lower apparent activation energies compared to that on CeO2 nanopolyhedras with dominating (111) facets and CeO2 nanocubes with dominating (100) facets. The higher activity for VOx/CeO2(110) might be related to the more abundant oxygen vacancies present on the (110) facets, evidenced from Raman spectroscopic measurements.

  5. Propane dehydrogenation catalyzed by ZSM-5 zeolites. A mechanistic study based on the selective energy transfer (SET) theory.

    Science.gov (United States)

    Larsson, Ragnar

    2015-02-02

    Experimentally determined activation energies of propane dehydrogenation catalyzed by ZSM-5 zeolites have been used to test the SET theory. The basis of this theory is that the catalyst system transfers vibrational energy via a resonance process to a specific vibration mode of the reacting molecule. Being excited up to a certain number of vibrational quanta the molecule is brought to reaction. By analyzing the above-mentioned activation energies we found the wave number of this "specific mode" to be 1065 cm-1. This is very close to the rocking vibration of propane (1053 cm-1). We suggest that the propane molecule reacts when excited so that the CH3 group has been forced towards a flat structure with a carbon atom hybridization that is more sp2 than sp3. Consequently there is no way for three H-atoms to bind to the carbon and one of them must leave. This is the starting point of the reaction. The isokinetic temperature of the system was found as Tiso = 727 ± 4 K. From the SET formula for Tiso when both energy-donating (ω) and energy-accepting (ν) vibrations have the same frequency, viz., Tiso = Nhcν/2R, we obtain ν = ω = 1011 ± 6 cm-1. This agrees rather well with the CH3 rocking mode (1053 cm-1) and also with asymmetric "TO4" stretching vibrations of the zeolite structure (ω).

  6. Ruthenium nanoparticles confined in SBA-15 as highly efficient catalyst for hydrolytic dehydrogenation of ammonia borane and hydrazine borane

    Science.gov (United States)

    Yao, Qilu; Lu, Zhang-Hui; Yang, Kangkang; Chen, Xiangshu; Zhu, Meihua

    2015-10-01

    Ultrafine ruthenium nanoparticles (NPs) within the mesopores of the SBA-15 have been successfully prepared by using a “double solvents” method, in which n-hexane is used as a hydrophobic solvent and RuCl3 aqueous solution is used as a hydrophilic solvent. After the impregnation and reduction processes, the samples were characterized by XRD, TEM, EDX, XPS, N2 adsorption-desorption, and ICP techniques. The TEM images show that small sized Ru NPs with an average size of 3.0 ± 0.8 nm are uniformly dispersed in the mesopores of SBA-15. The as-synthesized Ru@SBA-15 nanocomposites (NCs) display exceptional catalytic activity for hydrogen generation by the hydrolysis of ammonia borane (NH3BH3, AB) and hydrazine borane (N2H4BH3, HB) at room temperature with the turnover frequency (TOF) value of 316 and 706 mol H2 (mol Ru min)-1, respectively, relatively high values reported so far for the same reaction. The activation energies (Ea) for the hydrolysis of AB and HB catalyzed by Ru@SBA-15 NCs are measured to be 34.8 ± 2 and 41.3 ± 2 kJ mol-1, respectively. Moreover, Ru@SBA-15 NCs also show satisfied durable stability for the hydrolytic dehydrogenation of AB and HB, respectively.

  7. Effect of aluminum modification on catalytic properties of PtSn-based catalysts supported on SBA-15 for propane dehydrogenation

    Institute of Scientific and Technical Information of China (English)

    Yongzheng Duan; Yuming Zhou; Yiwei Zhang; Xiaoli Sheng; Shijian Zhou; Zewu Zhang

    2012-01-01

    The catalytic properties of PtSn-based catalysts supported on siliceous SBA-15 and Al-modified SBA-15,such as Al-incorporated SBA-15 (AlSBA-15) and alumina-modified SBA-15 (Al2O3/SBA-15),for propane dehydrogenation were investigated.Al2O3/SBA-15 was prepared either by an impregnation method using aluminum nitrate aqueous solution,or by the treatment of SBA-15 with a Al(OC3H7)3 solution in anhydrous toluene.N2-physisorption,FT-IR spectroscopy,solid-state 27Al MAS NMR spectroscopy,hydrogen chemisorption,XRF,NH3 temperature-programmed desorption,X-ray photoelectron spectroscopy and TPO were used to characterize these samples.Among these catalysts,the PtSn-based catalyst supported on Al2O3/SBA-15,which was grafted with Al(OC3H7)3,exhibited the best catalytic performance in terms of activity and stability The possible reason was due to the high Pt metal dispersion and/or the strong interactions among Pt,Sn,and the support.

  8. Optimized synthesis of L-sorbose by C(5)-dehydrogenation of D-sorbitol with Gluconobacter oxydans.

    Science.gov (United States)

    De Wulf, P; Soetaert, W; Vandamme, E J

    2000-08-01

    The optimization of L-sorbose synthesis by regiospecific dehydrogenation of D-sorbitol using Gluconobacter oxydans is reported. The current L-sorbose production processes that are based on G. oxydans and other bacterial strains are suboptimal as to yield and rate of L-sorbose synthesis. One reason for these problems is the toxicity that is induced by the substrate D-sorbitol when used in concentrations of >10% (w/v). This phenomenon significantly limits the potentials of L-sorbose production from an industrial point of view. The goal of this study was to develop a fast production process that yields L-sorbose in stoichiometric amounts starting from D-sorbitol concentrations that exceed 10% (w/v). A gradual improvement of the inoculum build-up procedure, culture medium composition, and process parameters ultimately led to a theoretically maximal L-sorbose productivity (200 g L(-1) of L-sorbose from 200 g L(-1) of D-sorbitol in 28 h of fermentation) using a Gluconobacter oxydans mutant strain that was selected under conditions of substrate inhibition. Because the D-sorbitol/L&HYPHEN;sorbose bioconversion is used to mass-produce vitamin C, the procedure reported here will contribute to a more efficient and more economic synthesis of vitamin C.

  9. Kinetics of the Oxidative Dehydrogenation of Isobutane over Cr2O3/La2(CO3)3

    Institute of Scientific and Technical Information of China (English)

    Yanping Sun; Tracey A. Robson; Trevor C. Brown

    2002-01-01

    The oxidative dehydrogenation (ODH) of isobutane over Cr2O3/La2(CO3)3 has been investi-gated in a low-pressure Knudsen cell reactor, under conditions where the kinetics of the primary reactionsteps can be accurately determined. By heating the catalyst at a constant rate from 150-300 ℃, temper-ature fluctuations due to non-equilibrium adsorption are minimized. The evolved gas profiles show thatODH to isobutene and water is a primary reaction pathway, while carbon dioxide, which forms from thecatalyst during reaction, is the only other product. This CO2 evolution may enhance the activity of thecatalyst. Isobutene formation proceeds with the participation of lattice oxygen from the Cr2O3/La2(CO3)3catalyst. The intrinsic Arrhenius rate constant for the ODH of isobutane isk(s-1) = 1011.5±2.2exp{-((55 ± 5) - △Hads kJmol-1)/RT}The small pre-exponential factor is expected for a concerted mechanism and for such a catalyst with asmall surface area and limited porosity.

  10. Kinetic study of propane dehydrogenation and catalyst deactivation over Pt-Sn/Al2O3 catalyst

    Institute of Scientific and Technical Information of China (English)

    Farnaz; Tahriri; Zangeneh; Abbas; Taeb; Khodayar; Gholivand; Saeed; Sahebdelfar

    2013-01-01

    The kinetics of propane dehydrogenation and catalyst deactivation over Pt-Sn/Al2O3 catalyst were studied.Performance test runs were carried out in a fixed-bed integral reactor.Using a power-law rate expression for the surface reaction kinetics and independent law for deactivation kinetics,the experimental data were analyzed both by integral and a novel differential method of analysis and the results were compared.To avoid fluctuation of time-derivatives of conversion required for differential analysis,the conversion-time data were first fitted with appropriate functions.While the time-zero and rate constant of reaction were largely insensitive to the function employed,the rate constant of deactivation was much more sensitive to the function form.The advantage of the proposed differential method,however,is that the integration of the rate expression is not necessary which otherwise could be complicated or impossible.It was also found that the reaction is not limited by external and internal mass transfer limitations,implying that the employed kinetics could be considered as intrinsic ones.

  11. Propane Dehydrogenation Catalyzed by ZSM-5 Zeolites. A Mechanistic Study Based on the Selective Energy Transfer (SET Theory

    Directory of Open Access Journals (Sweden)

    Ragnar Larsson

    2015-02-01

    Full Text Available Experimentally determined activation energies of propane dehydrogenation catalyzed by ZSM-5 zeolites have been used to test the SET theory. The basis of this theory is that the catalyst system transfers vibrational energy via a resonance process to a specific vibration mode of the reacting molecule. Being excited up to a certain number of vibrational quanta the molecule is brought to reaction. By analyzing the above-mentioned activation energies we found the wave number of this “specific mode” to be 1065 cm−1. This is very close to the rocking vibration of propane (1053 cm−1. We suggest that the propane molecule reacts when excited so that the CH3 group has been forced towards a flat structure with a carbon atom hybridization that is more sp2 than sp3. Consequently there is no way for three H-atoms to bind to the carbon and one of them must leave. This is the starting point of the reaction. The isokinetic temperature of the system was found as Tiso = 727 ± 4 K. From the SET formula for Tiso when both energy-donating (ω and energy-accepting (ν vibrations have the same frequency, viz., Tiso = Nhcν/2R, we obtain ν = ω = 1011 ± 6 cm−1. This agrees rather well with the CH3 rocking mode (1053 cm−1 and also with asymmetric “TO4” stretching vibrations of the zeolite structure (ω.

  12. An Intramolecular Silylene Borane Capable of Facile Activation of Small Molecules, Including Metal-Free Dehydrogenation of Water.

    Science.gov (United States)

    Mo, Zhenbo; Szilvási, Tibor; Zhou, Yu-Peng; Yao, Shenglai; Driess, Matthias

    2017-02-27

    The first single-component N-heterocyclic silylene borane 1 (LSi-R-BMes2 ; L=PhC(N(t) Bu)2 ; R=1,12-xanthendiyl spacer; Mes=2,4,6-Me3 C6 H2 ), acting as a frustrated Lewis pair (FLP) in small-molecule activation, can be synthesized in 65 % yields. Its HOMO is largely localized at the silicon(II) atom and the LUMO has mainly boron 2p character. In small-molecule activation 1 allows access to the intramolecular silanone-borane 3 featuring a Si=O→B interaction through reaction with O2 , N2 O, or CO2 , and formation of silanethione borane 4 from reaction with S8 . The Si(II) center in 1 undergoes immediate hydrogenation if exposed to H2 at 1 atm pressure in benzene, affording the silane borane 5-H2 , L(H2 )Si-R-BMes2 . Remarkably, no H2 activation occurs if the single silylene LSiPh and Mes3 B intermolecularly separated are exposed to dihydrogen. Unexpectedly, the pre-organized Si-B separation in 1 enables a metal-free dehydrogenation of H2 O to give the silanone-borane 3 as reactive intermediate.

  13. Studies on ethylbenzene dehydrogenation with CO2 as soft oxidant over Co3O4/COK-12 catalysts

    Indian Academy of Sciences (India)

    Ramudu Pochamoni; Anand Narani; Mohan Varkolu; Murali Dhar Gudimella; S Sai Prasad Potharaju; David Raju Burri; Seetha Rama Rao Kamaraju

    2015-04-01

    Oxidative dehydrogenation of ethylbenzene to styrene has been studied over Co3O4 supported on mesoporous silica (COK-12) with CO2 as soft oxidant in a fixed bed reactor at atmospheric pressure in the temperature range of 723 to 923K. While COK-12 has been prepared by self-assembly method using long chain ionic surfactant i.e., P123 as template, cobalt oxide supported on COK-12 catalysts with variable Co content have been synthesised by simple wet impregnation technique. All the catalysts were characterized by N2 adsorption - desorption, XRD, FT-IR, TPR, UV-Vis and XPS techniques. XRD and pore size distribution studies indicate the intactness of mesoporous structure of SiO2 even after incorporation of Co3O4. Presence of Co3O4 crystallites were observed beyond 5 wt% Co loading. High ethylbenzene conversion and stable styrene yields have been observed over 3% Co3O4/COK-12 catalyst due to the presence of large number of active Co3O4 catalytic sites. Enhancement in the activity has been observed with CO2 as soft oxidant than with N2 as diluent. This is because of the fact that the liberated H2 reacts with CO2 in the form of reverse water gas shift reaction.

  14. Effect of cerium addition on catalytic performance of PtSnNa/ZSM-5 catalyst for propane dehydrogenation

    Institute of Scientific and Technical Information of China (English)

    Mengwei Xue; Yuming Zhou; Yiwei Zhang; Xuan Liu; Yongzheng Duan; Xiaoli Sheng

    2012-01-01

    The effect of cerium addition on the catalytic performance of propane dehydrogenation over PtSnNa/ZSM-5 catalyst has been investigated by reaction tests and some physicochemical characterization such as XRD,BET,TEM,XPS.NH3-TPD,H2 chemisorption,TPR and TPO techniques.It has been found that with suitable amount of cerium addition,the platinum dispersion increased,while the carbon deposition tended to be eliminated easily.In these cases,the presence of cerium could not only realize the better distribution of metallic particles on the support,but also strengthen the interactions between Sn species and the support.Additionally,XPS spectra confirmed that more amounts of tin could exist in oxidized form,which was advantageous to the reaction.In our experiments,PtSnNaCe (1.1 wt%)/ZSM-5 catalyst exhibited the best catalytic performance.After running the reaction for 750 h,propane conversion was maintained higher than 30% with the corresponding selectivity to propylene of about 97%.

  15. Dehydrogenation of ethane to ethylene via radical pathways enhanced by alkali metal based catalyst in oxysteam condition

    KAUST Repository

    Takanabe, Kazuhiro

    2016-08-21

    The dehydrogenation of ethane to ethylene in the presence of oxygen and water was conducted using Na2WO4/SiO2 catalyst at high temperatures. At 923 K, the conversion rate without water was proportional to ethane pressure and a half order of oxygen pressure, consistent with a kinetically relevant step where an ethane molecule is activated with dissociated oxygen on the surface. When water was present, the ethane conversion rate was drastically enhanced. An additional term in the rate expression was proportional to a quarter of the oxygen pressure and a half order of the water pressure. This mechanism is consistent with the quasi-equilibrated OH radical formation with subsequent ethane activation. The attainable yield can be accurately described by taking the water contribution into consideration. At high conversion levels at 1073 K, the C2H4 yield exceeded 60% in a single-pass conversion. The C2H4 selectivity was almost insensitive to the C2H6 and O2 pressures. © 2016 American Institute of Chemical Engineers.

  16. Photocatalytic Ethanol Oxidative Dehydrogenation over Pt/TiO2: Effect of the Addition of Blue Phosphors

    Directory of Open Access Journals (Sweden)

    J. J. Murcia

    2012-01-01

    Full Text Available Ethanol oxidative dehydrogenation over Pt/TiO2 photocatalyst, in the presence and absence of blue phosphors, was performed. The catalyst was prepared by photodeposition of Pt on sulphated TiO2. This material was tested in a gas-solid photocatalytic fluidized bed reactor at high illumination efficiency. The effect of the addition of blue phosphors into the fluidized bed has been evaluated. The synthesized catalysts were extensively characterized by different techniques. Pt/TiO2 with a loading of 0.5 wt% of Pt appeared to be an active photocatalyst in the selective partial oxidation of ethanol to acetaldehyde improving its activity and selectivity compared to pure TiO2. In the same way, a notable enhancement of ethanol conversion in the presence of the blue phosphors has been obtained. The blue phosphors produced an increase in the level of ethanol conversion over the Pt/TiO2 catalyst, keeping at the same time the high selectivity to acetaldehyde.

  17. Improvement in dehydrogenation of MXH4 where M = Na, Li and X = Al, B confined in CNTs: a DFT investigation

    Science.gov (United States)

    Meenakshi; Agnihotri, Deepak; Jeet, Kiran; Sharma, Hitesh

    2016-11-01

    Nanoconfinement improves dehydrogenation kinetics of complex metal hydrides. The present paper reports effect of confinement of MXH4, where M = Na, Li and X = Al, B inside carbon nanotubes (CNTs) (n, 0) n = 9-11 chirality and diameter of 7.47 Å, 7.87 Å, 8.73 Å, respectively, using Density Functional calculations. The MXH4 interacts strongly with the surface atoms of CNT (11, 0) and is found to be the smallest stable system for confinement of MXH4 clusters. The Hydrogen release energy (E Hre) of NaAlH4 decreases sharply by 68.3 % , w.r.t. pure NaAlH4 cluster when confined inside CNT(11, 0). Similarly, in CNT (11, 0) E Hre decreases by 38.1 % for LiAlH4, 12.7 % for NaBH4 and 19.1 % for LiBH4. Thus, resulting confinement had a profound effect in improving the energetics of complex metal hydride nanoparticles without catalyst.

  18. Thermochemical Energy Storage through De/Hydrogenation of Organic Liquids: Reactions of Organic Liquids on Metal Hydrides.

    Science.gov (United States)

    Ulmer, Ulrich; Cholewa, Martin; Diemant, Thomas; Bonatto Minella, Christian; Dittmeyer, Roland; Behm, R Jürgen; Fichtner, Maximilian

    2016-06-08

    A study of the reactions of liquid acetone and toluene on transition metal hydrides, which can be used in thermal energy or hydrogen storage applications, is presented. Hydrogen is confined in TiFe, Ti0.95Zr0.05Mn1.49V0.45Fe0.06 ("Hydralloy C5"), and V40Fe8Ti26Cr26 after contact with acetone. Toluene passivates V40Fe8Ti26Cr26 completely for hydrogen desorption while TiFe is only mildly deactivated and desorption is not blocked at all in the case of Hydralloy C5. LaNi5 is inert toward both organic liquids. Gas chromatography (GC) investigations reveal that CO, propane, and propene are formed during hydrogen desorption from V40Fe8Ti26Cr26 in liquid acetone, and methylcyclohexane is formed in the case of liquid toluene. These reactions do not occur if dehydrogenated samples are used, which indicates an enhanced surface reactivity during hydrogen desorption. Significant amounts of carbon-containing species are detected at the surface and subsurface of acetone- and toluene-treated V40Fe8Ti26Cr26 by X-ray photoelectron spectroscopy (XPS). The modification of the surface and subsurface chemistry and the resulting blocking of catalytic sites is believed to be responsible for the containment of hydrogen in the bulk. The surface passivation reactions occur only during hydrogen desorption of the samples.

  19. Proximal Focal Femoral Deficiency

    Directory of Open Access Journals (Sweden)

    Vishal Kalia, Vibhuti

    2008-01-01

    Full Text Available Proximal focal femoral deficiency (PFFD is a developmental disorder of the proximal segment of thefemur and of acetabulum resulting in shortening of the affected limb and impairment of the function. It isa spectrum of congenital osseous anomalies characterized by a deficiency in the structure of the proximalfemur. The diagnosis is often made by radiological evaluation which includes identification and descriptionof PFFD and evaluation of associated limb anomalies by plain radiographs. Contrast arthrography orMagnetic Resonance Imaging is indicated when radiological features are questionable and to disclose thepresence and location of the femoral head and any cartilagenous anlage. The disorder is more commonlyunilateral and is apparent at birth. However, bilateral involvement is rarely seen. Therapy of the disorder isdirected towards satisfactory ambulation and specific treatment depending on the severity of dysplasia.

  20. Micronutrient deficiency in children.

    Science.gov (United States)

    Bhan, M K; Sommerfelt, H; Strand, T

    2001-05-01

    Malnutrition increases morbidity and mortality and affects physical growth and development, some of these effects resulting from specific micronutrient deficiencies. While public health efforts must be targeted to improve dietary intakes in children through breast feeding and appropriate complementary feeding, there is a need for additional measures to increase the intake of certain micronutrients. Food-based approaches are regarded as the long-term strategy for improving nutrition, but for certain micronutrients, supplementation, be it to the general population or to high risk groups or as an adjunct to treatment must also be considered. Our understanding of the prevalence and consequences of iron, vitamin A and iodine deficiency in children and pregnant women has advanced considerably while there is still a need to generate more knowledge pertaining to many other micronutrients, including zinc, selenium and many of the B-vitamins. For iron and vitamin A, the challenge is to improve the delivery to target populations. For disease prevention and growth promotion, the need to deliver safe but effective amounts of micronutrients such as zinc to children and women of fertile age can be determined only after data on deficiency prevalence becomes available and the studies on mortality reduction following supplementation are completed. Individual or multiple micronutrients must be used as an adjunct to treatment of common infectious diseases and malnutrition only if the gains are substantial and the safety window sufficiently wide. The available data for zinc are promising with regard to the prevention of diarrhea and pneumonia. It should be emphasized that there must be no displacement of important treatment such as ORS in acute diarrhea by adjunct therapy such as zinc. Credible policy making requires description of not only the clinical effects but also the underlying biological mechanisms. As findings of experimental studies are not always feasible to extrapolate to

  1. Orexin deficiency and narcolepsy

    OpenAIRE

    Sakurai, Takeshi

    2013-01-01

    Orexin deficiency results in the sleep disorder narcolepsy in many mammalian species, including mice, dogs, and humans, suggesting that the orexin system is particularly important for normal regulation of sleep/wakefulness states, and especially for maintenance of wakefulness. This review discusses animal models of narcolepsy; the contribution of each orexin receptor subtype to the narcoleptic phenotypes; and the etiology of orexin neuronal death. It also raises the possibility of novel thera...

  2. Iron-Deficiency Anemia (For Parents)

    Science.gov (United States)

    ... Your 1- to 2-Year-Old Iron-Deficiency Anemia KidsHealth > For Parents > Iron-Deficiency Anemia Print A ... common nutritional deficiency in children. About Iron-Deficiency Anemia Every red blood cell in the body contains ...

  3. Iron-Deficiency Anemia (For Parents)

    Science.gov (United States)

    ... Your 1- to 2-Year-Old Iron-Deficiency Anemia KidsHealth > For Parents > Iron-Deficiency Anemia A A ... common nutritional deficiency in children. About Iron-Deficiency Anemia Every red blood cell in the body contains ...

  4. Phenylalanine hydroxylase deficiency.

    Science.gov (United States)

    Mitchell, John J; Trakadis, Yannis J; Scriver, Charles R

    2011-08-01

    Phenylalanine hydroxylase deficiency is an autosomal recessive disorder that results in intolerance to the dietary intake of the essential amino acid phenylalanine. It occurs in approximately 1:15,000 individuals. Deficiency of this enzyme produces a spectrum of disorders including classic phenylketonuria, mild phenylketonuria, and mild hyperphenylalaninemia. Classic phenylketonuria is caused by a complete or near-complete deficiency of phenylalanine hydroxylase activity and without dietary restriction of phenylalanine most children will develop profound and irreversible intellectual disability. Mild phenylketonuria and mild hyperphenylalaninemia are associated with lower risk of impaired cognitive development in the absence of treatment. Phenylalanine hydroxylase deficiency can be diagnosed by newborn screening based on detection of the presence of hyperphenylalaninemia using the Guthrie microbial inhibition assay or other assays on a blood spot obtained from a heel prick. Since the introduction of newborn screening, the major neurologic consequences of hyperphenylalaninemia have been largely eradicated. Affected individuals can lead normal lives. However, recent data suggest that homeostasis is not fully restored with current therapy. Treated individuals have a higher incidence of neuropsychological problems. The mainstay of treatment for hyperphenylalaninemia involves a low-protein diet and use of a phenylalanine-free medical formula. This treatment must commence as soon as possible after birth and should continue for life. Regular monitoring of plasma phenylalanine and tyrosine concentrations is necessary. Targets of plasma phenylalanine of 120-360 μmol/L (2-6 mg/dL) in the first decade of life are essential for optimal outcome. Phenylalanine targets in adolescence and adulthood are less clear. A significant proportion of patients with phenylketonuria may benefit from adjuvant therapy with 6R-tetrahydrobiopterin stereoisomer. Special consideration must be

  5. Application of De-hydrogen Technology of High Pressure Carbon Dioxide in Urea Plant%高压二氧化碳脱氢技术在尿素装置的应用

    Institute of Scientific and Technical Information of China (English)

    左玉静; 张丛志

    2013-01-01

    In order to increase the safety of urea plant, the de-hydrogen device was arranged in the urea plant with CO2 stripping method with a ca-pacity of 400,000 t/a of Shandong Hualu Hengsheng Chemical Engineering Stock Company Ltd., before the raw gas of CO2 entered into high pressure system of urea.Author has introduced the working principle and the physical and chemical properties for de-hydrogen catalyst; has briefly described the process flow of the de-hydrogen device; has summarized the running situation of the de-hydrogen device; has presented the related matters to be noticed in case of applying of CO2 de-hydrogen technology.%山东华鲁恒升化工股份有限公司40万t/a CO2气提法尿素装置在原料气CO2进入尿素高压系统前设置了脱氢装置,以提高尿素装置的安全性。介绍了脱氢催化剂的工作原理和物化性能;简述了脱氢装置的工艺流程;总结了脱氢装置的运行情况;提出了应用CO2脱氢技术时应注意的相关事项。

  6. Genotypic and phenotypic spectrum of pyridoxine-dependent epilepsy (ALDH7A1 deficiency).

    Science.gov (United States)

    Mills, Philippa B; Footitt, Emma J; Mills, Kevin A; Tuschl, Karin; Aylett, Sarah; Varadkar, Sophia; Hemingway, Cheryl; Marlow, Neil; Rennie, Janet; Baxter, Peter; Dulac, Olivier; Nabbout, Rima; Craigen, William J; Schmitt, Bernhard; Feillet, François; Christensen, Ernst; De Lonlay, Pascale; Pike, Mike G; Hughes, M Imelda; Struys, Eduard A; Jakobs, Cornelis; Zuberi, Sameer M; Clayton, Peter T

    2010-07-01

    Pyridoxine-dependent epilepsy was recently shown to be due to mutations in the ALDH7A1 gene, which encodes antiquitin, an enzyme that catalyses the nicotinamide adenine dinucleotide-dependent dehydrogenation of l-alpha-aminoadipic semialdehyde/L-Delta1-piperideine 6-carboxylate. However, whilst this is a highly treatable disorder, there is general uncertainty about when to consider this diagnosis and how to test for it. This study aimed to evaluate the use of measurement of urine L-alpha-aminoadipic semialdehyde/creatinine ratio and mutation analysis of ALDH7A1 (antiquitin) in investigation of patients with suspected or clinically proven pyridoxine-dependent epilepsy and to characterize further the phenotypic spectrum of antiquitin deficiency. Urinary L-alpha-aminoadipic semialdehyde concentration was determined by liquid chromatography tandem mass spectrometry. When this was above the normal range, DNA sequencing of the ALDH7A1 gene was performed. Clinicians were asked to complete questionnaires on clinical, biochemical, magnetic resonance imaging and electroencephalography features of patients. The clinical spectrum of antiquitin deficiency extended from ventriculomegaly detected on foetal ultrasound, through abnormal foetal movements and a multisystem neonatal disorder, to the onset of seizures and autistic features after the first year of life. Our relatively large series suggested that clinical diagnosis of pyridoxine dependent epilepsy can be challenging because: (i) there may be some response to antiepileptic drugs; (ii) in infants with multisystem pathology, the response to pyridoxine may not be instant and obvious; and (iii) structural brain abnormalities may co-exist and be considered sufficient cause of epilepsy, whereas the fits may be a consequence of antiquitin deficiency and are then responsive to pyridoxine. These findings support the use of biochemical and DNA tests for antiquitin deficiency and a clinical trial of pyridoxine in infants and

  7. Iatrogenic nutritional deficiencies.

    Science.gov (United States)

    Young, R C; Blass, J P

    1982-01-01

    This article catalogs the nutritional deficiencies inadvertently introduced by certain treatment regimens. Specifically, the iatrogenic effects on nutrition of surgery, hemodialysis, irradiation, and drugs are reviewed. Nutritional problems are particularly frequent consequences of surgery on the gastrointestinal tract. Gastric surgery can lead to deficiencies of vitamin B12, folate, iron, and thiamine, as well as to metabolic bone disease. The benefits of small bowel bypass are limited by the potentially severe nutritional consequences of this procedure. Following bypass surgery, patients should be monitored for signs of possible nutritional probems such as weight loss, neuropathy, cardiac arrhythmias, loss of stamina, or changes in mental status. Minimal laboratory tests should include hematologic evaluation, B12, folate, iron, albumin, calcium, phosphorus, alkaline phosphatase, transaminases, sodium, potassium, chloride, and carbon dioxide levels. Roentgenologic examination of the bone should also be obtained. Loss of bone substance is a major consequence of many forms of treatment, and dietary supplementation with calcium is warranted. Patients undergoing hemodialysis have shown carnitine and choline deficiencies, potassium depletion, and hypovitaminosis, as well as osteomalacia. Chronic drug use may alter intake, synthesis, absorption, transport, storage, metabolism, or excretion of nutrients. Patients vary markedly in the metabolic effects of drugs, and recommendations for nutrition must be related to age, sex, reproductive status, and genetic endowment. Moreover, the illness being treated can itself alter nutritional requirements and the effect of the treatment on nutrient status. The changes in nutritional levels induced by use of estrogen-containing oral contraceptives (OCs) are obscure; however, the effects on folate matabolism appear to be of less clinical import than previously suggested. Reduction in pyridoxine and serum vitamin B12 levels has been

  8. Treatment of carnitine deficiency.

    Science.gov (United States)

    Winter, S C

    2003-01-01

    Carnitine deficiency is a secondary complication of many inborn errors of metabolism. Pharmacological treatment with carnitine not only corrects the deficiency, it facilitates removal of accumulating toxic acyl intermediates and the generation of mitochondrial free coenzyme A (CoA). The United States Food and Drug Administration (US FDA) approved the use of carnitine for the treatment of inborn errors of metabolism in 1992. This approval was based on retrospective chart analysis of 90 patients, with 18 in the untreated cohort and 72 in the treated cohort. Efficacy was evaluated on the basis of clinical and biochemical findings. Compelling data included increased excretion of disease-specific acylcarnitine derivatives in a dose-response relationship, decreased levels of metabolites in the blood, and improved clinical status with decreased hospitalization frequency, improved growth and significantly lower mortality rates as compared to historical controls. Complications of carnitine treatment were few, with gastrointestinal disturbances and odour being the most frequent. No laboratory or clinical safety issues were identified. Intravenous carnitine preparations were also approved for treatment of secondary carnitine deficiency. Since only 25% of enteral carnitine is absorbed and gastrointestinal tolerance of high doses is poor, parenteral carnitine treatment is an appealing alternative therapeutic approach. In 7 patients treated long term with high-dose weekly to daily venous boluses of parenteral carnitine through a subcutaneous venous port, benefits included decreased frequency of decompensations, improved growth, improved muscle strength and decreased reliance on medical foods with liberalization of protein intake. Port infections were the most troubling complication. Theoretical concerns continue to be voiced that carnitine might result in fatal arrhythmias in patients with long-chain fat metabolism defects. No published clinical studies substantiate these

  9. Isobutane dehydrogenation over chromia alumina catalysts prepared from MIL-101:Insight into chromium species on activity and selectivity

    Institute of Scientific and Technical Information of China (English)

    Huahua Zhao; Huanling Song; Zhichao Miao; Lingjun Chou

    2014-01-01

    Various mesoporous chromia alumina catalysts were prepared by five different methods based on a metal-organic framework MIL-101 and their catalytic performances over isobutane dehydrogenation were investigated. The highly dispersed chromium species were produced on catalyst KCrAl-I1 with largest specific surface area of 198 m2·g−1 prepared with aluminium isopropoxide (Al(i-OC3H7)3) by ultrasonic im-pregnation method. However, the catalyst KCrAl-I2 synthesized by stirring impregnation possessed crystallineα-Cr2O3 phase, which was poorly dispersed. Two types of Cr-rich and Al-rich CrxAl2−xO3 solid solutions, designated as CrAl-I and CrAl-II phase, were formed over the catalysts KCrAl-I3 (prepared by Al(i-OC3H7)3 with nitric acid regulation), KCrAl-C4 (prepared by aluminium chloride hexahydrate) and KCrAl-N5 (prepared by aluminium nitrate nonahydrate). Catalytic evaluation results revealed that KCrAl-I1 exhibited the high isobutane con-version due to its highly dispersed chromium species. However, KCrAl-I3, KCrAl-C4 and KCrAl-N5 showed the higher isobutene selectivity (95.2%−96.4%) on account of the formation of chromia alumina solid solutions in the catalysts. Moreover, the solid solution over the chromia alumina catalysts could greatly suppress the coke formation.

  10. Rare earth oxides doped NiO/γ-Al2O3 catalyst for oxidative dehydrogenation of cyclohexane

    Institute of Scientific and Technical Information of China (English)

    Hany M AbdelDayem; M Faiz; Hesham S Abdel-Samad; Salah A Hassan

    2015-01-01

    The effect of rare earth oxides (RE=Ce, La, Gd, and Dy) doping of alumina support in NiO/γ-Al2O3 system was investi-gated on its catalytic performance in oxidative dehydrogenation (ODH) of cyclohexane. The physicochemical properties of various samples were followed up through N2 physisorption, temperature programmed reduction (H2-TPR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and potentiometric acid-base titration techniques. In the parent NiO/γ-Al2O3 catalyst, Ni species were found to be strongly interacted with alumina surface. Addition of rare earth dopants toγ-Al2O3 in the catalyst system affected the nickel-alumina interaction and resulted in significant modifications in the catalytic performances in the ODH reaction. The results re-vealed the beneficial role of both La2O3 and Gd2O3 doping in enhancing the ODH catalytic activity and selectivity to cyclohexene. H2-TPR and XPS results indicated that majority of Ni species in NiO/La2O3 modifiedγ-Al2O3 were more weakly interacted with La2O3 and alumina whereas both NiO like species and nickel aluminate were present on the surface. Doping with cerium or dyspro-sium increased the nickel-support interaction and led to a decrease in surface nickel concentration. In case of doping with Ce, surface concentration of cerium oxide was higher than those of the other RE oxides; the doped catalyst reached its steady state activity faster than the other catalysts. The acid-base results suggested that RE metals were interacted most likely with acidic surface hydroxyl groups. The degree of nickel-alumina interaction decreased in the following order: LaAl>GdAl>CeAl>DyAl.

  11. Methanol Oxidative Dehydrogenation on Oxide Catalysts: Molecular and Dissociative Routes and Hydrogen Addition Energies as Descriptors of Reactivity

    Energy Technology Data Exchange (ETDEWEB)

    Deshlahra, Prashant; Iglesia, Enrique

    2014-11-13

    The oxidative dehydrogenation (ODH) of alkanols on oxide catalysts is generally described as involving H-abstraction from alkoxy species formed via O–H dissociation. Kinetic and isotopic data cannot discern between such routes and those involving kinetically-relevant H-abstraction from undissociated alkanols. Here, we combine such experiments with theoretical estimates of activation energies and entropies to show that the latter molecular routes prevail over dissociative routes for methanol reactions on polyoxometalate (POM) clusters at all practical reaction temperatures. The stability of the late transition states that mediate H-abstraction depend predominantly on the stability of the O–H bond formed, making H-addition energies (HAE) accurate and single-valued descriptors of reactivity. Density functional theory-derived activation energies depend linearly on HAE values at each O-atom location on clusters with a range of composition (H3PMo12, H4SiMo12, H3PW12, H4PV1Mo11, and H4PV1W11); both barriers and HAE values reflect the lowest unoccupied molecular orbital energy of metal centers that accept the electron and the protonation energy of O-atoms that accept the proton involved in the H-atom transfer. Bridging O-atoms form O–H bonds that are stronger than those of terminal atoms and therefore exhibit more negative HAE values and higher ODH reactivity on all POM clusters. For each cluster composition, ODH turnover rates reflect the reactivity-averaged HAE of all accessible O-atoms, which can be evaluated for each cluster composition to provide a rigorous and accurate predictor of ODH reactivity for catalysts with known structure. These relations together with oxidation reactivity measurements can then be used to estimate HAE values and to infer plausible structures for catalysts with uncertain active site structures.

  12. Significantly improved dehydrogenation of ball-milled MgH2 doped with CoFe2O4 nanoparticles

    Science.gov (United States)

    Shan, Jiawei; Li, Ping; Wan, Qi; Zhai, Fuqiang; Zhang, Jun; Li, Ziliang; Liu, Zhaojiang; Volinsky, Alex A.; Qu, Xuanhui

    2014-12-01

    CoFe2O4 nanoparticles are added to magnesium hydride (MgH2) by high-energy ball milling in order to improve its hydriding properties. The hydrogen storage properties and catalytic mechanism are investigated by pressure-composition-temperature (PCT), differential thermal analysis (DTA), X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The nonisothermal desorption results show that the onset desorption temperature of the MgH2 + 7 mol% CoFe2O4 is 160 °C, which is 200 °C lower than of the as-received MgH2. The dehydrogenation process of the MgH2 doped with the CoFe2O4 nanoparticles includes two steps. DTA curves and XRD patterns reveal that a chemical reaction happens between MgH2 and CoFe2O4, forming the final products of the ternary combination, corresponding to Co3Fe7, MgO and Co. The onset desorption temperature of the ball-milled MgH2 doped with Co3Fe7, MgO and Co is about 260 °C, approximately 100 °C lower than the un-doped MgH2, demonstrating that the ternary combination (Co3Fe7, MgO, and Co) also has a great catalytic effect on the MgH2 hydrogen storage properties. It is also confirmed that the various methods of adding the ternary combination have different effects on the MgH2 hydriding-dehydriding process.

  13. Ethylbenzene dehydrogenation over FeOx/(Mg,Zn)(Al)O catalysts derived from hydrotalcites: Role of MgO as basic sites

    KAUST Repository

    Balasamy, Rabindran J.

    2011-05-01

    A series of Mg3-xZnxFe0.5Al0.5 mixed oxide catalysts derived from hydrotalcites were tested in the ethylbenzene dehydrogenation to styrene in He atmosphere at 550 °C. The catalysts were prepared by coprecipitation from the nitrates of metal components followed by calcination to mixed oxides at 550 °C. A part of Mg2+ in Mg 3Fe0.5Al0.5 mixed oxide was replaced with Zn2+ to test the effect of MgO as the support. The mixed oxides were composed of periclase and spinel-type compounds with a high surface area of 100-180m2gcat-1. Mössbauer and XPS measurements indicated the presence of Fe3+ on the catalysts and H2-TPR measurement suggested that the dehydrogenation reaction is catalyzed by the reduction-oxidation between Fe3+/Fe2+. The activity of Mg3-xZnxFe0.5Al0.5 mixed oxide decreased with increasing x, indicating an important role of MgO on the activity. Both CO2-TPD measurements as well as IR measurements of adsorbed CO2 clearly indicated the presence of basic sites of Mg 2+O2- on the catalysts. It seems that the combination of Mg2+O2- and Fe3+ was essential for the catalytic activity. It is concluded that the surface base sites generated on O2- bound Mg2+ near Fe3+ sites are responsible for H+-abstraction; the dehydrogenation of ethylbenzene was initiated by the H+ abstraction on Mg2+O2- basic sites, and accelerated by the reduction-oxidation of Fe3+/Fe2+ active species. © 2011 Elsevier B.V.

  14. Mg3(VO4)2-MgO-ZrO2 nano-catalysts for oxidative dehydrogenation of n-butane.

    Science.gov (United States)

    Lee, Jong Kwon; Seo, Hyun; Hong, Ung Gi; Yoo, Yeonshick; Cho, Young-Jin; Lee, Jinsuk; Park, Gle; Chang, Hosik; Song, In Kyu

    2014-11-01

    A series of X-Mg3(VO4)2-MgO-ZrO2 nano-catalysts with different vanadium content (X = 3.3, 5.3, 7.0, 10.2, and 13.4) were prepared by a single-step citric acid-derived sol-gel method for use in the oxidative dehydrogenation of n-butane to n-butene and 1,3-butadiene. The effect of vanadium content of X-Mg3(VO4)2-MgO-ZrO2 nano-catalysts on their physicochemical properties and catalytic activities in the oxidative dehydrogenation of n-butane was investigated. Successful formation of X-Mg3(VO4)2-MgO-ZrO2 nano-catalysts was confirmed by XRD, Raman spectroscopy, and ICP-AES analyses. The catalytic performance of X-Mg3(VO4)2-MgO-ZrO2 nano-catalysts strongly depended on vanadium content. All the X-Mg3(VO4)2-MgO-ZrO2 nano-catalysts showed a stable catalytic performance without catalyst deactivation during the reaction. Among the catalysts tested, 7.0-Mg3(VO4)2-MgO-ZrO2 nano-catalyst showed the best catalytic performance in terms of yield for total dehydrogenation products (TDP, n-butene and 1,3-butadiene). TPRO (temperature-programmed reoxidation) experiments were carried out to measure the oxygen capacity of the catalyst. Experimental results revealed that oxygen capacity of the catalyst was closely related to the catalytic performance. Yield for TDP increased with increasing oxygen capacity of the catalyst.

  15. A liquid-based eutectic system: LiBH4·NH 3-nNH3BH3 with high dehydrogenation capacity at moderate temperature

    KAUST Repository

    Tan, Yingbin

    2011-01-01

    A novel eutectic hydrogen storage system, LiBH4·NH 3-nNH3BH3, which exists in a liquid state at room temperature, was synthesized through a simple mixing of LiBH 4·NH3 and NH3BH3 (AB). In the temperature range of 90-110 °C, the eutectic system showed significantly improved dehydrogenation properties compared to the neat AB and LiBH 4·NH3 alone. For example, in the case of the LiBH4·NH3/AB with a mole ratio of 1:3, over 8 wt.% hydrogen could be released at 90 °C within 4 h, while only 5 wt.% hydrogen released from the neat AB at the same conditions. Through a series of experiments it has been demonstrated that the hydrogen release of the new system is resulted from an interaction of AB and the NH3 group in the LiBH4·NH3, in which LiBH4 works as a carrier of ammonia and plays a crucial role in promoting the interaction between the NH3 group and AB. The enhanced dehydrogenation of LiBH 4·NH3/AB may result from the polar liquid state reaction environments and the initially promoted formation of the diammoniate of diborane, which will facilitate the B-H⋯H-N interaction between LiBH4·NH3 and AB. Kinetics analysis revealed that the rate-controlling steps of the dehydrogenation process are three-dimensional diffusion of hydrogen at temperatures ranging from 90 to 110 °C. This journal is © The Royal Society of Chemistry.

  16. Phosphorus Deficiency in Ducklins

    Institute of Scientific and Technical Information of China (English)

    CuiHengmin; LuoLingping

    1995-01-01

    20 one-day-old Tianfu ducklings were fed on a natural diet deficient in phosphorus(Ca 0.80%,P 0.366%)for three weeks and examined for signs and lesions.Signs began to appear at the age of one week,and became serous at two weeks.13 ducklings died during the experiment.Morbidity was 100% and mortality was 65%.The affected ducklings mainly showed leg weakness,severe lamencess,deprssion,lack of appetite and stunted growth,The serum alkaline phosphatase activities increased markedly.The serum phosphorus concentration,tibial ash,ash calcium and phosphorus content decreased obviously.At necropsy,maxillae and ribe were soft,and the latter was crooked.Long ones were soft and broke easily.The hypertrophic zone of the growth-plate in the epiphysis of long ones was lengthened and osteoid tissue increased in the metaphyseal spongiosa histopathologically.The above mentioned symptoms and lesions could be prevented by adding phosphorus to the natural deficient diet(up to 0.65%),The relationship between lesions and signs,pathomorphological characterisation and pathogensis were also discussed in this paper.

  17. Glucose-6-phosphatase deficiency

    Directory of Open Access Journals (Sweden)

    Labrune Philippe

    2011-05-01

    Full Text Available Abstract Glucose-6-phosphatase deficiency (G6P deficiency, or glycogen storage disease type I (GSDI, is a group of inherited metabolic diseases, including types Ia and Ib, characterized by poor tolerance to fasting, growth retardation and hepatomegaly resulting from accumulation of glycogen and fat in the liver. Prevalence is unknown and annual incidence is around 1/100,000 births. GSDIa is the more frequent type, representing about 80% of GSDI patients. The disease commonly manifests, between the ages of 3 to 4 months by symptoms of hypoglycemia (tremors, seizures, cyanosis, apnea. Patients have poor tolerance to fasting, marked hepatomegaly, growth retardation (small stature and delayed puberty, generally improved by an appropriate diet, osteopenia and sometimes osteoporosis, full-cheeked round face, enlarged kydneys and platelet dysfunctions leading to frequent epistaxis. In addition, in GSDIb, neutropenia and neutrophil dysfunction are responsible for tendency towards infections, relapsing aphtous gingivostomatitis, and inflammatory bowel disease. Late complications are hepatic (adenomas with rare but possible transformation into hepatocarcinoma and renal (glomerular hyperfiltration leading to proteinuria and sometimes to renal insufficiency. GSDI is caused by a dysfunction in the G6P system, a key step in the regulation of glycemia. The deficit concerns the catalytic subunit G6P-alpha (type Ia which is restricted to expression in the liver, kidney and intestine, or the ubiquitously expressed G6P transporter (type Ib. Mutations in the genes G6PC (17q21 and SLC37A4 (11q23 respectively cause GSDIa and Ib. Many mutations have been identified in both genes,. Transmission is autosomal recessive. Diagnosis is based on clinical presentation, on abnormal basal values and absence of hyperglycemic response to glucagon. It can be confirmed by demonstrating a deficient activity of a G6P system component in a liver biopsy. To date, the diagnosis is most

  18. Glucose-6-phosphatase deficiency.

    Science.gov (United States)

    Froissart, Roseline; Piraud, Monique; Boudjemline, Alix Mollet; Vianey-Saban, Christine; Petit, François; Hubert-Buron, Aurélie; Eberschweiler, Pascale Trioche; Gajdos, Vincent; Labrune, Philippe

    2011-05-20

    Glucose-6-phosphatase deficiency (G6P deficiency), or glycogen storage disease type I (GSDI), is a group of inherited metabolic diseases, including types Ia and Ib, characterized by poor tolerance to fasting, growth retardation and hepatomegaly resulting from accumulation of glycogen and fat in the liver. Prevalence is unknown and annual incidence is around 1/100,000 births. GSDIa is the more frequent type, representing about 80% of GSDI patients. The disease commonly manifests, between the ages of 3 to 4 months by symptoms of hypoglycemia (tremors, seizures, cyanosis, apnea). Patients have poor tolerance to fasting, marked hepatomegaly, growth retardation (small stature and delayed puberty), generally improved by an appropriate diet, osteopenia and sometimes osteoporosis, full-cheeked round face, enlarged kydneys and platelet dysfunctions leading to frequent epistaxis. In addition, in GSDIb, neutropenia and neutrophil dysfunction are responsible for tendency towards infections, relapsing aphtous gingivostomatitis, and inflammatory bowel disease. Late complications are hepatic (adenomas with rare but possible transformation into hepatocarcinoma) and renal (glomerular hyperfiltration leading to proteinuria and sometimes to renal insufficiency). GSDI is caused by a dysfunction in the G6P system, a key step in the regulation of glycemia. The deficit concerns the catalytic subunit G6P-alpha (type Ia) which is restricted to expression in the liver, kidney and intestine, or the ubiquitously expressed G6P transporter (type Ib). Mutations in the genes G6PC (17q21) and SLC37A4 (11q23) respectively cause GSDIa and Ib. Many mutations have been identified in both genes,. Transmission is autosomal recessive. Diagnosis is based on clinical presentation, on abnormal basal values and absence of hyperglycemic response to glucagon. It can be confirmed by demonstrating a deficient activity of a G6P system component in a liver biopsy. To date, the diagnosis is most commonly confirmed

  19. [Iron deficiency and digestive disorders].

    Science.gov (United States)

    Cozon, G J N

    2014-11-01

    Iron deficiency anemia still remains problematic worldwide. Iron deficiency without anemia is often undiagnosed. We reviewed, in this study, symptoms and syndromes associated with iron deficiency with or without anemia: fatigue, cognitive functions, restless legs syndrome, hair loss, and chronic heart failure. Iron is absorbed through the digestive tract. Hepcidin and ferroportin are the main proteins of iron regulation. Pathogenic micro-organisms or intestinal dysbiosis are suspected to influence iron absorption.

  20. Management of Iron Deficiency Anemia

    OpenAIRE

    Jimenez, Kristine; Kulnigg-Dabsch, Stefanie; Gasche, Christoph

    2015-01-01

    Anemia affects one-fourth of the world’s population, and iron deficiency is the predominant cause. Anemia is associated with chronic fatigue, impaired cognitive function, and diminished well-being. Patients with iron deficiency anemia of unknown etiology are frequently referred to a gastroenterologist because in the majority of cases the condition has a gastrointestinal origin. Proper management improves quality of life, alleviates the symptoms of iron deficiency, and reduces the need for blo...

  1. CATALYTIC DEHYDROGENATION OF LONG CHAIN ALKANES IN SUPERCRITICAL PHASE%超临界相中的长链烷烃催化脱氢

    Institute of Scientific and Technical Information of China (English)

    魏伟; 孙予罕; 钟炳

    1999-01-01

    @@ The preparation of olefins from long chain alkanes by catalytic dehydrogenation is an important process in synthetic detergents and surface-active agents[1]. Because of equilibrium limitation, the present process only reaches about 10 % of the conversion with 90 % of the selectivity. In addition, the lifetime of the catalysts ( e. g. Pt-Sn/Al2O3) is around 40 d owing to the severe coke formation even with n(H2 )/n(alkane)= 8. Although the catalysts have been well improved, both conversion and selectivity were hardly enhanced. New technique is therefore required to improve the process.

  2. Effects of Zeolite Structure and Si/Al Ratio on Adsorption Thermodynamics and Intrinsic Kinetics of Monomolecular Cracking and Dehydrogenation of Alkanes over Bronsted Acid Sites

    Science.gov (United States)

    Janda, Amber Leigh

    It is well known that the efficacy of acidic zeolite catalysts for the cracking of hydrocarbons originates from the shape and size of the zeolite pores. However, the mechanisms by which changes in pore structure influence cracking kinetics are not well understood or exploited. The aim of this dissertation is to use experiments and simulations to shed light on the ways by which zeolite structure and acid site location affect the apparent and intrinsic kinetics of n-alkane monomolecular cracking and dehydrogenation. In the rate-determining step of these processes, C-C or C-H bonds are cleaved catalytically by Bronsted protons. Thus, the kinetics of monomolecular activation reactions are useful for characterizing the influence of active site structural environment on catalysis. In Chapter 2, the effects of active site distribution on n-butane monomolecular activation kinetics are investigated for commercial samples of MFI having a range of the Si/Al ratio. Based on UV-visible spectroscopic analyses of (Co,Na)-MFI, it is inferred that, with increasing Al concentration, the fraction of Co---and, by extension, Bronsted protons in H-MFI---located at channel intersections increases relative to the fraction located at channels. Concurrently, the first-order rate coefficients (kapp) for cracking and dehydrogenation, the selectivity to terminal cracking versus central cracking, and the selectivity to dehydrogenation versus cracking increase. The stronger dependence of the selectivity to dehydrogenation on Al content is attributed to a product-like transition state, the stability of which is more sensitive to confinement than the stabilities of cracking transition states, which occur earlier along the reaction coordinate. For terminal cracking and dehydrogenation, the intrinsic activation entropy (DeltaS‡int ) increases with Al content, consistent with the larger dimensions of intersections relative to channels. Surprisingly, the rate of dehydrogenation is inhibited by

  3. Effect of the plasma-chemical treatment of ZnO and NiO on their activity in the dehydrogenation of isopropanol

    Science.gov (United States)

    Danilova, M. N.; Pylinina, A. I.; Platonov, E. A.; Yagodovskii, V. D.

    2015-08-01

    Treating ZnO and NiO oxides with glow discharge oxygen plasma and high-frequency argon plasma is found to affect the catalytic activity of these oxides in the dehydrogenation reaction of isopropanol, leading to an increase in the conversion of alcohol and the yield of acetone. The increased activity of ZnO is due to the high number of acid sites induced by plasma-chemical treatment. With NiO, the increased activity results from the formation of new, more active sites with low experimental activation energy, rather than a change in the surface acidity.

  4. Generation of decarboxylated and dehydrogenated betacyanins in thermally treated purified fruit extract from purple pitaya (Hylocereus polyrhizus) monitored by LC-MS/MS.

    Science.gov (United States)

    Wybraniec, Sławomir; Mizrahi, Yosef

    2005-08-24

    Pigments of purple pitaya [Hylocereus polyrhizus (F.A.C. Weber) Britton and Rose] fruits were submitted to extraction and were decarboxylated during heating experiments in acidified ethanolic and aqueous solutions. Groups of betacyanins with different decarboxylation levels were identified in the heating products by LC-DAD and LC-MS/MS. The main decarboxylation products were 2-decarboxy-betacyanins, 17-decarboxy-betacyanins, and 2,17-bidecarboxy-betacyanins. The structures of other compounds were assigned to 2,15,17-tridecarboxy-betacyanins and 14,15-dehydrogenated derivatives (neo-derivatives) of all decarboxylated betacyanins found.

  5. Deep oxidation in propane oxidative dehydrogenation to propene over V_2O_5/γ-Al_2O_3 studied by in-situ DRIFTS

    Institute of Scientific and Technical Information of China (English)

    Yunbing He; Hongbing Ji; Jianhua Xu; Lefu Wang

    2009-01-01

    In-situ DRIFTS was used to study the deep oxidation of propane,a side reaction during propane oxidative dehydrogenation to propene. Strong adsorption of propene was supposed to be the main reason for the deep oxidation. It was found that gaseous oxygen in the feed and the reaction temperature had great influence on the reaction. To obtain a relative high selectivity to propene,the reaction temperature should be maintained at 150~250 ℃ with a proper content of gaseous oxygen in the feed for a certain catalyst and some modifiers which could weaken the adsorption of pmpene on the catalyst surface would be favorable.

  6. Hydroformylation of olefins and reductive carbonylation of aryl halides with syngas formed ex situ from dehydrogenative decarbonylation of hexane-1,6-diol

    DEFF Research Database (Denmark)

    Christensen, Stig Holden; Olsen, Esben Paul Krogh; Rosenbaum, Jascha;

    2014-01-01

    A variety of primary alcohols have been investigated as convenient substrates for the ex situ delivery of carbon monoxide and molecular hydrogen in a two-chamber reactor. The gaseous mixture is liberated in one chamber by an iridium-catalysed dehydrogenative decarbonylation of the alcohol...... and then consumed in the other chamber in either a rhodium-catalysed hydroformylation of olefins or a palladium-catalysed reductive carbonylation of aryl halides. Hexane-1,6-diol was found to be the optimum alcohol for both reactions where moderate to excellent yields were obtained of the product aldehydes...

  7. Nutritional deficiencies after bariatric surgery.

    Science.gov (United States)

    Bal, Bikram S; Finelli, Frederick C; Shope, Timothy R; Koch, Timothy R

    2012-09-01

    Lifestyle intervention programmes often produce insufficient weight loss and poor weight loss maintenance. As a result, an increasing number of patients with obesity and related comorbidities undergo bariatric surgery, which includes approaches such as the adjustable gastric band or the 'divided' Roux-en-Y gastric bypass (RYGB). This Review summarizes the current knowledge on nutrient deficiencies that can develop after bariatric surgery and highlights follow-up and treatment options for bariatric surgery patients who develop a micronutrient deficiency. The major macronutrient deficiency after bariatric surgery is protein malnutrition. Deficiencies in micronutrients, which include trace elements, essential minerals, and water-soluble and fat-soluble vitamins, are common before bariatric surgery and often persist postoperatively, despite universal recommendations on multivitamin and mineral supplements. Other disorders, including small intestinal bacterial overgrowth, can promote micronutrient deficiencies, especially in patients with diabetes mellitus. Recognition of the clinical presentations of micronutrient deficiencies is important, both to enable early intervention and to minimize long-term adverse effects. A major clinical concern is the relationship between vitamin D deficiency and the development of metabolic bone diseases, such as osteoporosis or osteomalacia; metabolic bone diseases may explain the increased risk of hip fracture in patients after RYGB. Further studies are required to determine the optimal levels of nutrient supplementation and whether postoperative laboratory monitoring effectively detects nutrient deficiencies. In the absence of such data, clinicians should inquire about and treat symptoms that suggest nutrient deficiencies.

  8. Catalytic Dehydrogenation over Pd-Supported ZSM-5 Zeolite for o-Phenylphenol Synthesis%载钯ZSM-5分子筛催化脱氢合成邻苯基苯酚

    Institute of Scientific and Technical Information of China (English)

    蔡春; 吕春绪

    2001-01-01

    Pd-supported ZSM-5 zeolites prepared through ion exchange technique were used as a dehydrogenation catalyst for synthesis of o-phenylphenol from cyclohexanone. When Si/A1 ratio in the catalyst was 85: 1 or more, an obvious reduction in attenuation rate of catalyst activity was observed.When the Si/Al ratio was of 17 . 1 or less, polymer compounds could be formed on the surface of zeolite, that would decrease the dehydrogenation activity due to the reduction of the specific surface area of the catalyst.

  9. Discussion pressure swing adsorption technology of Butane dehydrogenation tail gas extracting hydrogen%从丁烷脱氢尾气提取氢气的变压吸附方法讨论

    Institute of Scientific and Technical Information of China (English)

    屈玉玺; 迟建光

    2015-01-01

    丁烷脱氢尾气提取氢气变压吸附技术是一种新型的气体分离技术,本文探讨从丁烷脱氢尾气提取氢气的变压吸附方法。%Butane dehydrogenation tail gas extracting hydrogen pressure swing adsorption technology is a new type of gas separation technology, this paper discusses the pressure swing adsorption method of extracting hydrogen from butane dehydrogenation tail gas.

  10. Iodine deficiency in Europe.

    Science.gov (United States)

    Delange, F

    1995-01-18

    Iodine is a trace element present in the human body in minute amounts (15-20 mg in adults, i.e. 0.0285 x 10(-3)% of body weight). The only confirmed function of iodine is to constitute an essential substrate for the synthesis of thyroid hormones, tetraiodothyronine, thyroxine or T4 and triiodothyronine, T3 (1). In thyroxine, iodine is 60% by weight. Thyroid hormones, in turn, play a decisive role in the metabolism of all cells of the organism (2) and in the process of early growth and development of most organs, especially of the brain (3). Brain development in humans occurs from fetal life up to the third postnatal year (4). Consequently, a deficit in iodine and/or in thyroid hormones occurring during this critical period of life will result not only in the slowing down of the metabolic activities of all the cells of the organism but also in irreversible alterations in the development of the brain. The clinical consequence will be mental retardation (5). When the physiological requirements of iodine are not met in a given population, a series of functional and developmental abnormalities occur (Table 1), including thyroid function abnormalities and, when iodine deficiency is severe, endemic goiter and cretinism, endemic mental retardation, decreased fertility rate, increased perinatal death, and infant mortality. These complications, which constitute an hindrance to the development of the affected population, are grouped under the general heading of Iodine Deficiency Disorders, IDD (6). Broad geographic areas exist in which the population is affected by IDD.(ABSTRACT TRUNCATED AT 250 WORDS)

  11. Iron deficiency and iron deficiency anemia in women.

    Science.gov (United States)

    Coad, Jane; Pedley, Kevin

    2014-01-01

    Iron deficiency is one of the most common nutritional problems in the world and disproportionately affects women and children. Stages of iron deficiency can be characterized as mild deficiency where iron stores become depleted, marginal deficiency where the production of many iron-dependent proteins is compromised but hemoglobin levels are normal and iron deficiency anemia where synthesis of hemoglobin is decreased and oxygen transport to the tissues is reduced. Iron deficiency anemia is usually assessed by measuring hemoglobin levels but this approach lacks both specificity and sensitivity. Failure to identify and treat earlier stages of iron deficiency is concerning given the neurocognitive implications of iron deficiency without anemia. Most of the daily iron requirement is derived from recycling of senescent erythrocytes by macrophages; only 5-10 % comes from the diet. Iron absorption is affected by inhibitors and enhancers of iron absorption and by the physiological state. Inflammatory conditions, including obesity, can result in iron being retained in the enterocytes and macrophages causing hypoferremia as a strategic defense mechanism to restrict iron availability to pathogens. Premenopausal women usually have low iron status because of iron loss in menstrual blood. Conditions which further increase iron loss, compromise absorption or increase demand, such as frequent blood donation, gastrointestinal lesions, athletic activity and pregnancy, can exceed the capacity of the gastrointestinal tract to upregulate iron absorption. Women of reproductive age are at particularly high risk of iron deficiency and its consequences however there is a controversial argument that evolutionary pressures have resulted in an iron deficient phenotype which protects against infection.

  12. Iron deficiency and cardiovascular disease

    NARCIS (Netherlands)

    von Haehling, Stephan; Jankowska, Ewa A.; van Veldhuisen, Dirk J.; Ponikowski, Piotr; Anker, Stefan D.

    2015-01-01

    Iron deficiency affects up to one-third of the world's population, and is particularly common in elderly individuals and those with certain chronic diseases. Iron excess can be detrimental in cardiovascular illness, and research has now also brought anaemia and iron deficiency into the focus of card

  13. Iron deficiency anemia in children

    OpenAIRE

    Pochinok, T. V.

    2016-01-01

    In the article the role of iron in the human body is highlighted. The mechanism of development of iron deficiency states, their consequences and the basic principles of diagnosis and correction of children of different ages are shown.Key words: children, iron deficiency anemia, treatment.

  14. Nanoflake-assembled Al2O3-supported CeO2-ZrO2 as an efficient catalyst for oxidative dehydrogenation of ethylbenzene with CO2

    Science.gov (United States)

    Wang, Tehua; Guan, Xiaolin; Lu, Huiyi; Liu, Zhongwen; Ji, Min

    2017-03-01

    An Al2O3 material assembled by nanoflakes was used to prepare supported CeO2-ZrO2 catalyst via a deposition-precipitation method for oxidative dehydrogenation of ethylbenzene with CO2. Both unsupported and commercial Al2O3-supported CeO2-ZrO2 were prepared for comparison. It was found that the CeO2-ZrO2/nanoflake-assembled Al2O3 catalyst exhibited the best catalytic activity. The characterization results revealed that the slit-shape pores existing in nanoflake-assembled Al2O3 were responsible for the small particle size and high Ce/Zr surface ratio of supported CeO2-ZrO2 species. The dispersion of Ce1-xZrx(OH)4 precursors onto Al2O3 support surface during the deposition-precipitation process was proposed. The high dispersion and large numbers of surface oxygen vacancies of the CeO2-ZrO2 species on nanoflake-assembled Al2O3 contributed to the excellent catalytic performance in oxidative dehydrogenation of ethylbenzene with CO2. This kind of special Al2O3 is expected to be a promising support for preparing highly dispersed metal/metal oxide catalysts.

  15. Dehydrogenation of propane in the presence of CO{sub 2} over polyacid chromium oxide catalysts modified by Mo, W and Mn

    Energy Technology Data Exchange (ETDEWEB)

    Lapidus, A.L.; Agafonov, Yu.A.; Gaidai, N.A.; Nekrasov, N.V.; Davydov, P.E. [Russian Academy of Sciences, Moscow (Russian Federation). N.D. Zelinsky Institute of Organic Chemistry

    2013-11-01

    Effective chromium oxide catalysts without additions and with addition of Mo, W and Mn were prepared and tested in long-duration experiments for propane dehydrogenation in the presence of CO{sub 2}. The optimal concentrations of metals were found. It was shown that the best combination of acid-base and redox properties necessary for a decrease of aggregation of chromium-oxide particles was observed over the following catalyst: (3.0 wt.%Cr-1.5 wt.% Mn)/SiO{sub 2}. This catalyst worked stably in durable tests (500 h). Mechanism of propane oxidative dehydrogenation was studied using unstationary response method. It was shown that the process mechanism was similar over all studied catalysts but the catalysts were differed by the adsorption capacity of the reaction components: CO{sub 2} was tied more firmly than C{sub 3}H{sub 6} over Cr and Cr-Mn, C{sub 3}H{sub 6} was tied more strongly than CO{sub 2} over Cr-W. The reverse water-gas shift reaction proceeded in more extent over chromium-oxide catalysts without additions. (orig.)

  16. The Effect of Sulphate Doping on Nanosized TiO2 and MoOx/TiO2 Catalysts in Cyclohexane Photooxidative Dehydrogenation

    Directory of Open Access Journals (Sweden)

    P. Ciambelli

    2008-01-01

    Full Text Available The effect of sulphate doping of titania in promoting activity and selectivity of MoOx/TiO2 catalysts for the cyclohexane photooxidative dehydrogenation has been investigated in a gas-solid fluidized bed reactor. Sulphate and/or molybdate-modified titania catalysts were prepared by incipient wet impregnation of nanosized (5–10 nm crystallite size samples. At 60% of titania surface coverage by MoOx, sulphate surface density was obtained up to 19 μmol/m2 without formation of MoO3. The catalysts were characterized by N2 adsorption-desorption at −196∘C, micro-Raman and UV-visible reflectance spectroscopy, thermogravimetric analysis coupled with mass spectroscopy (TG-MS, and mass titration. Unsulphated and sulphated titania are both active in cyclohexane total oxidation, but sulphate doping of titania has a detrimental effect on the reaction rate. On Mo-based catalysts, polymolybdate species enabled sulphated titania to convert cyclohexane to benzene (99% selectivity and cyclohexene, reducing at zero the formation of CO2. Cyclohexane conversion to benzene is almost linearly dependent on sulphate surface density, resulting in enhanced yield to benzene. The enhanced photooxidative dehydrogenation activity and benzene yield by sulphate doping could be attributed to the increase of surface acidity and, as a consequence, of cyclohexane adsorption.

  17. ED-XAS Data Reveal In-situ Time-Resolved Adsorbate Coverage on Supported Molybdenum Oxide Catalysts during Propane Dehydrogenation

    Science.gov (United States)

    Ramaker, David; Gatewood, Daniel; Beale, Andrew M.; Weckhuysen, Bert M.

    2007-02-01

    Energy-Dispersive X-ray Absorption Spectroscopy (ED-XAS) data combined with UV/Vis, Raman, and mass spectrometry data on alumina- and silica-supported molybdenum oxide catalysts under propane dehydrogenation conditions have been previously reported. A novel Δμ adsorbate isolation technique was applied here to the time-resolved (0.1 min) Mo K-edge ED-XAS data by taking the difference of absorption, μ, at t>1 against the initial time, t=0. Further, full multiple scattering calculations using the FEFF 8.0 code are performed to interpret the Δμ signatures. The resulting difference spectra and interpretation provide real time propane coverage and O depletion at the MoOn surface. The propane coverage is seen to correlate with the propene and/or coke production, with the maximum coke formation occurring when the propane coverage is the largest. Combined, these data give unprecedented insight into the complicated dynamics for propane dehydrogenation.

  18. Synthesis of defect-rich, (001) faceted-ZnO nanorod on a FTO substrate as efficient photocatalysts for dehydrogenation of isopropanol to acetone

    Science.gov (United States)

    Tan, Sin Tee; Umar, Akrajas Ali; Salleh, Muhamad Mat

    2016-06-01

    Highly oriented ZnO nanorod was successfully synthesised on Ag nanoseed coated FTO substrate via a microwave hydrolysis approach. It was found that the morphology and the optical properties of the ZnO nanorod are strongly influenced by the power of the microwave irradiation used during the growth process. The aspect ratio of the nanorods changed from high to low with the increasing of microwave power. It was also found that the optical band gap of the ZnO nanorod red shifted with the increasing of the microwave power, reflecting an excellent tune ability of the optical properties of ZnO nanorods. The photocatalytic activity of these unique nanorod was evaluated by a dehydrogenation process of isopropanol to acetone in the presence of ZnO nanorod. It was found that the ZnO nanorod exhibited an excellent catalytic performance by showing an ability to accelerate the production of 0.031 mol L-1 of acetone within only 35 min or 0.9 mmol L-1 min-1 from isopropyl alcohol dehydrogenation. It was almost no conversion from isopropyl alcohol when ZnO nanorods was absence during the reaction. In this report, a detailed mechanism of ZnO nanorod formation and the relationship between morphology and optical energy band gap are described.

  19. Organometallic model complexes elucidate the active gallium species in alkane dehydrogenation catalysts based on ligand effects in Ga K-edge XANES

    Energy Technology Data Exchange (ETDEWEB)

    Getsoian, Andrew “Bean”; Das, Ujjal; Camacho-Bunquin, Jeffrey; Zhang, Guanghui; Gallagher, James R.; Hu, Bo; Cheah, Singfoong; Schaidle, Joshua A.; Ruddy, Daniel A.; Hensley, Jesse E.; Krause, Theodore R.; Curtiss, Larry A.; Miller, Jeffrey T.; Hock, Adam S.

    2016-01-01

    Gallium-modified zeolites are known catalysts for the dehydrogenation of alkanes, reactivity that finds industrial application in the aromatization of light alkanes by Ga-ZSM5. While the role of gallium cations in alkane activation is well known, the oxidation state and coordination environment of gallium under reaction conditions has been the subject of debate. Edge shifts in Ga K-edge XANES spectra acquired under reaction conditions have long been interpreted as evidence for reduction of Ga(III) to Ga(I). However, a change in oxidation state is not the only factor that can give rise to a change in the XANES spectrum. In order to better understand the XANES spectra of working catalysts, we have synthesized a series of molecular model compounds and grafted surface organometallic Ga species and compared their XANES spectra to those of gallium-based catalysts acquired under reducing conditions. We demonstrate that changes in the identity and number of gallium nearest neighbors can give rise to changes in XANES spectra similar to those attributed in literature to changes in oxidation state. Specifically, spectral features previously attributed to Ga(I) may be equally well interpreted as evidence for low-coordinate Ga(III) alkyl or hydride species. These findings apply both to gallium-impregnated zeolite catalysts and to silica-supported single site gallium catalysts, the latter of which is found to be active and selective for dehydrogenation of propane and hydrogenation of propylene.

  20. Novel Flower-Like Ag-SiO2-MgO-Al2O3 Material: Preparation, Characterization and Catalytic Application in Methanol Dehydrogenation

    Institute of Scientific and Technical Information of China (English)

    LI,Jing-Xia; REN,Li-Ping; DAI,Wei-Lin; CAO,Yong; FAN,Kang-Nian

    2008-01-01

    Catalytic direct dehydrogenation of methanol to formaldehyde was carried out over Ag-SiO2-MgO-Al2O3 catalysts prepared by sol-gel method.The optimal preparation mass fractions were determined as 8.3% MgO,16.5% Al2O3 and 20% silver loading.Using this optimum catalyst,excellent activity and selectivity were obtained.The conversion of methanol and the selectivity to formaldehyde both reached 100%,which were much higher than other previously reported silver supported catalysts.Based on combined characterizations,such as X-ray diffraction (XRD),scanning electronic microscopy (SEM),diffuse reflectance ultraviolet-visible spectroscopy (UV-Vis,DRS),nitrogen adsorption at low temperature,temperature programmed desorption of ammonia (NH3-TPD),desorption of CO2 (CO2-TPD),etc.,the correlation of the catalytic performance to the structural properties of the Ag-SiO2-MgO-Al2O3 catalyst was discussed in detail.This perfect catalytic performance in the direct dehydrogenation of methanol to formaldehyde without any side-products is attributed to its unique flower-like structure with a surface area less than 1 m2/g,and the strong interactions between neutralized support and the nano-sized Ag particles as active centers.

  1. Evaluation of the Parameters and Conditions of Process in the Ethylbenzene Dehydrogenation with Application of Permselective Membranes to Enhance Styrene Yield

    Science.gov (United States)

    Araújo, Paulo Jardel P.; Leite, Manuela Souza; Kakuta Ravagnani, Teresa M.

    2016-01-01

    Styrene is an important monomer in the manufacture of thermoplastic. Most of it is produced by the catalytic dehydrogenation of ethylbenzene. In this process that depends on reversible reactions, the yield is usually limited by the establishment of thermodynamic equilibrium in the reactor. The styrene yield can be increased by using a hybrid process, with reaction and separation simultaneously. It is proposed using permselective composite membrane to remove hydrogen and thus suppress the reverse and secondary reactions. This paper describes the simulation of a dehydrogenation process carried out in a tubular fixed-bed reactor wrapped in a permselective composite membrane. A mathematical model was developed, incorporating the various mass transport mechanisms found in each of the membrane layers and in the catalytic fixed bed. The effects of the reactor feed conditions (temperature, steam-to-oil ratio, and the weight hourly space velocity), the fixed-bed geometry (length, diameter, and volume), and the membrane geometry (thickness of the layers) on the styrene yield were analyzed. These variables were used to determine experimental conditions that favour the production of styrene. The simulation showed that an increase of 40.98% in the styrene yield, compared to a conventional fixed-bed process, could be obtained by wrapping the reactor in a permselective composite membrane. PMID:27069982

  2. Single-Site VO x Moieties Generated on Silica by Surface Organometallic Chemistry: A Way To Enhance the Catalytic Activity in the Oxidative Dehydrogenation of Propane

    KAUST Repository

    Barman, Samir

    2016-07-26

    We report here an accurate surface organometallic chemistry (SOMC) approach to propane oxidative dehydrogenation (ODH) using a μ2-oxo-bridged, bimetallic [V2O4(acac)2] (1) (acac = acetylacetonate anion) complex as a precursor. The identity and the nuclearity of the product of grafting and of the subsequent oxidative treatment have been systematically studied by means of FT-IR, Raman, solid-state (SS) NMR, UV-vis DRS, EPR and EXAFS spectroscopies. We show that the grafting of 1 on the silica surface under a rigorous SOMC protocol and the subsequent oxidative thermal treatment lead exclusively to well-defined and isolated monovanadate species. The resulting material has been tested for the oxidative dehydrogenation of propane in a moderate temperature range (400-525 °C) and compared with that of silica-supported vanadium catalysts prepared by the standard impregnation technique. The experimental results show that the catalytic activity in propane ODH is strongly upgraded by the degree of isolation of the VOx species that can be achieved by employing the SOMC protocol. © 2016 American Chemical Society.

  3. In-situ catalyzation approach for enhancing the hydrogenation/dehydrogenation kinetics of MgH2 powders with Ni particles

    Science.gov (United States)

    El-Eskandarany, M. Sherif; Shaban, Ehab; Ali, Naser; Aldakheel, Fahad; Alkandary, Abdullah

    2016-11-01

    One practical solution for utilizing hydrogen in vehicles with proton-exchange fuel cells membranes is storing hydrogen in metal hydrides nanocrystalline powders. According to its high hydrogen capacity and low cost of production, magnesium hydride (MgH2) is a desired hydrogen storage system. Its slow hydrogenation/dehydrogenation kinetics and high thermal stability are the major barriers restricting its usage in real applications. Amongst the several methods used for enhancing the kinetics behaviors of MgH2 powders, mechanically milling the powders with one or more catalyst species has shown obvious advantages. Here we are proposing a new approach for gradual doping MgH2 powders with Ni particles upon ball milling the powders with Ni-balls milling media. This proposed is-situ method showed mutually beneficial for overcoming the agglomeration of catalysts and the formation of undesired Mg2NiH4 phase. Moreover, the decomposition temperature and the corresponding activation energy showed low values of 218 °C and 75 kJ/mol, respectively. The hydrogenation/dehydrogenation kinetics examined at 275 °C of the powders milled for 25 h took place within 2.5 min and 8 min, respectively. These powders containing 5.5 wt.% Ni performed 100-continuous cycle-life time of hydrogen charging/discharging at 275 °C within 56 h without failure or degradation.

  4. Pd-Ag Membrane Coupled to a Two-Zone Fluidized Bed Reactor (TZFBR for Propane Dehydrogenation on a Pt-Sn/MgAl2O4 Catalyst

    Directory of Open Access Journals (Sweden)

    Miguel Menéndez

    2013-05-01

    Full Text Available Several reactor configurations have been tested for catalytic propane dehydrogenation employing Pt-Sn/MgAl2O4 as a catalyst. Pd-Ag alloy membranes coupled to the multifunctional Two-Zone Fluidized Bed Reactor (TZFBR provide an improvement in propane conversion by hydrogen removal from the reaction bed through the inorganic membrane in addition to in situ catalyst regeneration. Twofold process intensification is thereby achieved when compared to the use of traditional fluidized bed reactors (FBR, where coke formation and thermodynamic equilibrium represent important process limitations. Experiments were carried out at 500–575 °C and with catalyst mass to molar flow of fed propane ratios between 15.1 and 35.2 g min mmol−1, employing three different reactor configurations: FBR, TZFBR and TZFBR + Membrane (TZFBR + MB. The results in the FBR showed catalyst deactivation, which was faster at high temperatures. In contrast, by employing the TZFBR with the optimum regenerative agent flow (diluted oxygen, the process activity was sustained throughout the time on stream. The TZFBR + MB showed promising results in catalytic propane dehydrogenation, displacing the reaction towards higher propylene production and giving the best results among the different reactor configurations studied. Furthermore, the results obtained in this study were better than those reported on conventional reactors.

  5. Iron deficiency anemia in children.

    Science.gov (United States)

    Subramaniam, Girish; Girish, Meenakshi

    2015-06-01

    Iron deficiency is not just anemia; it can be responsible for a long list of other manifestations. This topic is of great importance, especially in infancy and early childhood, for a variety of reasons. Firstly, iron need is maximum in this period. Secondly, diet in infancy is usually deficient in iron. Thirdly and most importantly, iron deficiency at this age can result in neurodevelopmental and cognitive deficits, which may not be reversible. Hypochromia and microcytosis in a complete blood count (CBC) makes iron deficiency anemia (IDA) most likely diagnosis. Absence of response to iron should make us look for other differential diagnosis like β thalassemia trait and anemia of chronic disease. Celiac disease is the most important cause of true IDA not responding to oral iron therapy. While oral ferrous sulphate is the cheapest and most effective therapy for IDA, simple nonpharmacological and pharmacological measures can go a long way in prevention of iron deficiency.

  6. Genetics Home Reference: isolated growth hormone deficiency

    Science.gov (United States)

    ... Home Health Conditions isolated growth hormone deficiency isolated growth hormone deficiency Enable Javascript to view the expand/collapse ... Download PDF Open All Close All Description Isolated growth hormone deficiency is a condition caused by a severe ...

  7. Genetics Home Reference: familial HDL deficiency

    Science.gov (United States)

    ... Genetics Home Health Conditions familial HDL deficiency familial HDL deficiency Enable Javascript to view the expand/collapse ... Download PDF Open All Close All Description Familial HDL deficiency is a condition characterized by low levels ...

  8. Genetics Home Reference: eosinophil peroxidase deficiency

    Science.gov (United States)

    ... Genetics Home Health Conditions eosinophil peroxidase deficiency eosinophil peroxidase deficiency Enable Javascript to view the expand/collapse ... Download PDF Open All Close All Description Eosinophil peroxidase deficiency is a condition that affects certain white ...

  9. Genetics Home Reference: protein C deficiency

    Science.gov (United States)

    ... Management Genetic Testing (1 link) Genetic Testing Registry: Thrombophilia, hereditary, due to protein C deficiency, autosomal dominant ... my area? Other Names for This Condition hereditary thrombophilia due to protein C deficiency PROC deficiency Related ...

  10. Iron Deficiency Anemia in Pregnancy.

    Science.gov (United States)

    Breymann, Christian

    2015-10-01

    Anemia is a common problem in obstetrics and perinatal care. Any hemoglobin below 10.5 g/dL can be regarded as true anemia regardless of gestational age. Reasons for anemia in pregnancy are mainly nutritional deficiencies, parasitic and bacterial diseases, and inborn red blood cell disorders such as thalassemias. The main cause of anemia in obstetrics is iron deficiency, which has a worldwide prevalence between estimated 20%-80% and consists of a primarily female population. Stages of iron deficiency are depletion of iron stores, iron-deficient erythropoiesis without anemia, and iron deficiency anemia, the most pronounced form of iron deficiency. Pregnancy anemia can be aggravated by various conditions such as uterine or placental bleedings, gastrointestinal bleedings, and peripartum blood loss. In addition to the general consequences of anemia, there are specific risks during pregnancy for the mother and the fetus such as intrauterine growth retardation, prematurity, feto-placental miss ratio, and higher risk for peripartum blood transfusion. Besides the importance of prophylaxis of iron deficiency, the main therapy options for the treatment of pregnancy anemia are oral iron and intravenous iron preparations.

  11. Ca(AlH4)2, CaAlH5, and CaH2+6LiBH4: Calculated dehydrogenation enthalpy, including zero point energy, and the structure of the phonon spectra

    NARCIS (Netherlands)

    Marashdeh, A.; Frankcombe, T.J.

    2008-01-01

    The dehydrogenation enthalpies of Ca(AlH4)2, CaAlH5, and CaH2+6LiBH4 have been calculated using density functional theory calculations at the generalized gradient approximation level. Harmonic phonon zero point energy (ZPE) corrections have been included using Parlinski’s direct method. The dehydrog

  12. Ca(AlH4)2, CaAlH5, and CaH2+6LiBH4: Calculated dehydrogenation enthalpy, including zero point energy, and the structure of the phonon spectra.

    Science.gov (United States)

    Marashdeh, Ali; Frankcombe, Terry J

    2008-06-21

    The dehydrogenation enthalpies of Ca(AlH(4))(2), CaAlH(5), and CaH(2)+6LiBH(4) have been calculated using density functional theory calculations at the generalized gradient approximation level. Harmonic phonon zero point energy (ZPE) corrections have been included using Parlinski's direct method. The dehydrogenation of Ca(AlH(4))(2) is exothermic, indicating a metastable hydride. Calculations for CaAlH(5) including ZPE effects indicate that it is not stable enough for a hydrogen storage system operating near ambient conditions. The destabilized combination of LiBH(4) with CaH(2) is a promising system after ZPE-corrected enthalpy calculations. The calculations confirm that including ZPE effects in the harmonic approximation for the dehydrogenation of Ca(AlH(4))(2), CaAlH(5), and CaH(2)+6LiBH(4) has a significant effect on the calculated reaction enthalpy. The contribution of ZPE to the dehydrogenation enthalpies of Ca(AlH(4))(2) and CaAlH(5) calculated by the direct method phonon analysis was compared to that calculated by the frozen-phonon method. The crystal structure of CaAlH(5) is presented in the more useful standard setting of P2(1)c symmetry and the phonon density of states of CaAlH(5), significantly different to other common complex metal hydrides, is rationalized.

  13. In situ UV–Vis diffuse reflectance spectroscopy — on line activity measurements of supported chromium oxide catalysts: relating isobutane dehydrogenation activity with Cr-speciation via experimental design

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Verberckmoes, A.A.; Debaere, J.; Ooms, K.; Langhans, I.; Schoonheydt, R.A.

    2000-01-01

    The dehydrogenation of isobutane over supported chromium oxide catalysts was studied by a combination of in situ UV–Vis diffuse reflectance spectroscopy and on line GC analysis. A well-defined set of experiments, based on an experimental design, was carried out to develop mathematical models, which

  14. Genetics Home Reference: hereditary antithrombin deficiency

    Science.gov (United States)

    ... Merck Manual Home Edition for Patients and Caregivers: Thrombophilia National Blood Clot Alliance: Antithrombin Deficiency Orphanet: Hereditary thrombophilia due to congenital antithrombin deficiency Patient Support and ...

  15. Helicobacterpy loriinfection and micronutrient deficiencies

    Institute of Scientific and Technical Information of China (English)

    Javed Yakoob; Wasim Jafri; Shahab Abid

    2003-01-01

    It is known that deficiencies of micronutrients due to infections increase morbidity and mortality. This phenomenon depicts itself conspicuously in developing countries.Deficiencies of iron, vitamins A, E, C, B12, etc are widely prevalent among populations living in the third world countries. Helicobacterpylori (Hpylori) infection has a high prevalence throughout the world. Deficiencies of several micronutrients due to Hpylori infection may be concomitantly present and vary from subtle sub-clinical states to severe clinical disorders. These essential trace elementsl micronutrients are involved in host defense mechanisms,maintaining epithelial cell integrity, glycoprotein synthesis,transport mechanisms, myocardial contractility, brain development, cholesterol and glucose metabolism. In this paper Hpyloriinfection in associaed with various micronutrients deficiencies is briefly reviewed.

  16. Vitamin D deficiency in adolescents

    OpenAIRE

    Ashraf T Soliman; Vincenzo De Sanctis; Rania Elalaily; Said Bedair; Islam Kassem

    2014-01-01

    The prevalence of severe vitamin D deficiency (VDD) in adolescents is variable but considerably high in many countries, especially in Middle-east and Southeast Asia. Different factors attribute to this deficiency including lack of sunlight exposure due to cultural dress codes and veiling or due to pigmented skin, and less time spent outdoors, because of hot weather, and lower vitamin D intake. A potent adaptation process significantly modifies the clinical presentation and therefore clinical ...

  17. Iron deficiency and cognitive functions

    OpenAIRE

    Jáuregui-Lobera I

    2014-01-01

    Ignacio Jáuregui-Lobera Department of Nutrition and Bromatology, Pablo de Olavide University, Seville, Spain Abstract: Micronutrient deficiencies, especially those related to iodine and iron, are linked to different cognitive impairments, as well as to potential long-term behavioral changes. Among the cognitive impairments caused by iron deficiency, those referring to attention span, intelligence, and sensory perception functions are mainly cited, as well as those associated with...

  18. Core-shell structured nanospheres with mesoporous silica shell and Ni core as a stable catalyst for hydrolytic dehydrogenation of ammonia borane

    Institute of Scientific and Technical Information of China (English)

    Hua; Liu; Changyan; Cao; Ping; Li; Yu; Yu; Weiguo; Song

    2014-01-01

    Core-shell structured nanospheres with mesoporous silica shell and Ni core(denoted as Ni@meso-SiO2) are prepared through a three-step process. Monodispersed Ni precursors are first prepared, and then coated with mesoporous SiO2. Final Ni@meso-SiO2spheres are obtained after calcination. The products are characterized by X-ray powder diffraction, transmission electron microscopy and N2adsorption-desorption methods. These spheres have a high surface area and are well dispersed in water, showing a high catalytic activity with a TOF value of 18.5,and outstanding stability in hydrolytic dehydrogenation of ammonia borane at room temperature.

  19. Synthesis and characterization of TiO2 –SiO2 nanoparticles as catalyst for dehydrogenation of 1,4-dihydropyridines

    Indian Academy of Sciences (India)

    F Farzaneh; L Jafarie Fourozune

    2014-02-01

    Nanoparticles of binary TiO2–SiO2 mixed oxides was prepared via sol–gel method using tetraethylorthosilicate (TEOS) and titanium isopropoxide (TIPP) in different reaction conditions (solvent and pH) using ammonium hyhdroxide, acetic acid, sodium hydroxide, ethyleneglycol and polyethylene glycol followed by calcination at 850–970° C. The morphologies, structures and chemical compositions were determined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and Fourier transmission infrared spectroscopy (FTIR) techniques. The catalytic activity of the obtained nanomaterials was explored for the dehydrogenation of 1,4-dihydropyridines (1,4-DHPs). Observation of 86–100% conversion and 100% selectivity towards the formation of desired products with prepared nanoparticles will be discussed here.

  20. Catalytic Dehydrogenation of n-Butane over V/SiO2 Catalyst: A Comparison with Cr/SiO2 Catalyst

    Institute of Scientific and Technical Information of China (English)

    Xu Yuebing; Fu Wenting; Lu Jiangyin; Wang Jide

    2008-01-01

    V/SiO2 catalysts compared to Cr/SiO2 catalysts were studied for dehydrogenation of n-butane to butenes.Several methods for characterization of catalysts such as FT-IR,UV-vis and Raman spectroscopies were used.Some differences between two catalysts were showed,including the performances of catalysts,distribution of products and mechanism of reactions.The results showed that prepared catalysts with 12m% of active component loading all demonstrated best conversion of n-butane to butene at a reaction temperature of around 590℃.Two different reaction mechanisms were mentioned to well explain why iso-butene was produced on V/SiO2 catalysts but not on Cr/SiO2 catalysts.

  1. Probing the electronic structure of M-graphene oxide (M = Ni, Co, NiCo) catalysts for hydrolytic dehydrogenation of ammonia borane

    Science.gov (United States)

    Zhao, Binhua; Liu, Jinyin; Zhou, Litao; Long, Dan; Feng, Kun; Sun, Xuhui; Zhong, Jun

    2016-01-01

    Various metal elements (M = Ni, Co, NiCo) were dispersed on graphene oxide (GO) to form the M-GO hybrids by a facile way. The hybrids showed good catalytic activities in the hydrolytic dehydrogenation of ammonia borane (AB, NH3BH3), which were significantly enhanced when compared to the metal nanoparticles or GO alone. The electronic structure of the hybrids has been probed by scanning transmission X-ray microscopy (STXM). The distribution of metal elements was clearly imaged with identical electronic structure. Moreover, an interfacial interaction between metal and GO was observed with the peak intensity proportional to the catalytic performance in the hydrolysis of AB. The results provide new insight into the enhanced performance of the M-GO hybrids and may help for the design of advanced catalysts.

  2. In vitro analysis of the monolignol coupling mechanism using dehydrogenative polymerization in the presence of peroxidases and controlled feeding ratios of coniferyl and sinapyl alcohol.

    Science.gov (United States)

    Moon, Sun-Joo; Kwon, Mi; Choi, Donha; Won, Keehoon; Kim, Yong Hwan; Choi, In-Gyu; Choi, Joon Weon

    2012-10-01

    In this study, dehydrogenative polymers (DHP) were synthesized in vitro through dehydrogenative polymerization using different ratios of coniferyl alcohol (CA) and sinapyl alcohol (SA) (10:0, 8:2, 6:4, 2:8, 0:10), in order to investigate the monolignol coupling mechanism in the presence of horseradish peroxidase (HRP), Coprinus cinereus peroxidase (CiP) or soybean peroxidase (SBP) with H(2)O(2), respectively. The turnover capacities of HRP, CiP and SBP were also measured for coniferyl alcohol (CA) and sinapyl alcohol (SA), and CiP and SBP were found to have the highest turnover capacity for CA and SA, respectively. The yields of HRP-catalyzed DHP (DHP-H) and CiP-catalyzed DHP (DHP-C) were estimated between ca. 7% and 72% based on the original weights of CA/SA in these synthetic conditions. However, a much lower yield of SBP-catalyzed DHP (DHP-S) was produced compared to that of DHP-H and DHP-C. In general, the DHP yields gradually increased as the ratio of CA/SA increased. The average molecular weight of DHP-H also increased with increasing CA/SA ratios, while those of DHP-C and DHP-S were not influenced by the ratios of monolignols. The frequency of β-O-4 linkages in the DHPs decreased with increasing CA/SA ratios, indicating that the formation of β-O-4 linkages during DHP synthesis was influenced by peroxidase type.

  3. Metallic glassy Zr70Ni20Pd10 powders for improving the hydrogenation/dehydrogenation behavior of MgH2.

    Science.gov (United States)

    El-Eskandarany, M Sherif

    2016-05-25

    Because of its low density, storage of hydrogen in the gaseous and liquids states possess technical and economic challenges. One practical solution for utilizing hydrogen in vehicles with proton-exchange fuel cells membranes is storing hydrogen in metal hydrides. Magnesium hydride (MgH2) remains the best hydrogen storage material due to its high hydrogen capacity and low cost of production. Due to its high activation energy and poor hydrogen sorption/desorption kinetics at moderate temperatures, the pure form of MgH2 is usually mechanically treated by high-energy ball mills and catalyzed with different types of catalysts. These steps are necessary for destabilizing MgH2 to enhance its kinetics behaviors. In the present work, we used a small mole fractions (5 wt.%) of metallic glassy of Zr70Ni20Pd10 powders as a new enhancement agent to improve its hydrogenation/dehydrogenation behaviors of MgH2. This short-range ordered material led to lower the decomposition temperature of MgH2 and its activation energy by about 121 °C and 51 kJ/mol, respectively. Complete hydrogenation/dehydrogenation processes were successfully achieved to charge/discharge about 6 wt.%H2 at 100 °C/200 °C within 1.18 min/3.8 min, respectively. In addition, this new nanocomposite system shows high performance of achieving continuous 100 hydrogen charging/discharging cycles without degradation.

  4. Mechanical and Thermal Dehydrogenation of Lithium Alanate (LiAlH4 and Lithium Amide (LiNH2 Hydride Composites

    Directory of Open Access Journals (Sweden)

    Leszek Zbroniec

    2012-04-01

    Full Text Available Hydrogen storage properties of the (nLiAlH4 + LiNH2 hydride composite where n = 1, 3, 11.5 and 30, synthesized by high energy ball milling have been investigated. The composite with the molar ratio n = 1 releases large quantities of H2 (up to ~5 wt.% during ball milling up to 100–150 min. The quantity of released H2 rapidly decreases for the molar ratio n = 3 and is not observed for n = 11.5 and 30. The XRD studies indicate that the H2 release is a result of a solid state decomposition of LiAlH4 into (1/3Li3AlH6 + (2/3Al + H2 and subsequently decomposition of (1/3Li3AlH6 into LiH + (1/3Al + 0.5H2. Apparently, LiAlH4 is profoundly destabilized during ball milling by the presence of a large quantity of LiNH2 (37.7 wt.% in the n = 1 composite. The rate of dehydrogenation at 100–170 °C (at 1 bar H2 is adversely affected by insufficient microstructural refinement, as observed for the n = 1 composite, which was milled for only 2 min to avoid H2 discharge during milling. XRD studies show that isothermal dehydrogenation of (nLiAlH4 + LiNH2 occurs by the same LiAlH4 decomposition reactions as those found during ball milling. The ball milled n = 1 composite stored under Ar at 80 °C slowly discharges large quantities of H2 approaching 3.5 wt.% after 8 days of storage.

  5. Metallic glassy Zr70Ni20Pd10 powders for improving the hydrogenation/dehydrogenation behavior of MgH2

    Science.gov (United States)

    El-Eskandarany, M. Sherif

    2016-05-01

    Because of its low density, storage of hydrogen in the gaseous and liquids states possess technical and economic challenges. One practical solution for utilizing hydrogen in vehicles with proton-exchange fuel cells membranes is storing hydrogen in metal hydrides. Magnesium hydride (MgH2) remains the best hydrogen storage material due to its high hydrogen capacity and low cost of production. Due to its high activation energy and poor hydrogen sorption/desorption kinetics at moderate temperatures, the pure form of MgH2 is usually mechanically treated by high-energy ball mills and catalyzed with different types of catalysts. These steps are necessary for destabilizing MgH2 to enhance its kinetics behaviors. In the present work, we used a small mole fractions (5 wt.%) of metallic glassy of Zr70Ni20Pd10 powders as a new enhancement agent to improve its hydrogenation/dehydrogenation behaviors of MgH2. This short-range ordered material led to lower the decomposition temperature of MgH2 and its activation energy by about 121 °C and 51 kJ/mol, respectively. Complete hydrogenation/dehydrogenation processes were successfully achieved to charge/discharge about 6 wt.%H2 at 100 °C/200 °C within 1.18 min/3.8 min, respectively. In addition, this new nanocomposite system shows high performance of achieving continuous 100 hydrogen charging/discharging cycles without degradation.

  6. Clinical manifestation of myeloperoxidase deficiency.

    Science.gov (United States)

    Lanza, F

    1998-09-01

    Myeloperoxidase (MPO), an iron-containing heme protein localized in the azurophilic granules of neutrophil granulocytes and in the lysosomes of monocytes, is involved in the killing of several micro-organisms and foreign cells, including bacteria, fungi, viruses, red cells, and malignant and nonmalignant nucleated cells. Despite the primary role of the oxygen-dependent MPO system in the destruction of certain phagocytosed microbes, subjects with total or partial MPO deficiency generally do not have an increased frequency of infections, probably because other MPO-independent mechanism(s) for microbicidal activity compensate for the lack of MPO. Infectious diseases, especially with species of Candida, have been observed predominantly in MPO-deficient patients who also have diabetes mellitus, but the frequency of such cases is very low, less than 5% of reported MPO-deficient subjects. Evidence from a number of investigators indicates that individuals with total MPO deficiency show a high incidence of malignant tumors. Since MPO-deficient PMNs exhibit in vitro a depressed lytic action against malignant human cells, it can be speculated that the neutrophil MPO system plays a central role in the tumor surveillance of the host. However, any definitive conclusion on the association between MPO deficiency and the occurrence of cancers needs to be confirmed in further clinical studies. Clinical manifestations of this disorder depend on the nature of the defect; an acquired abnormality associated with other hematological or nonhematological diseases has been occasionally described, but the primary deficiency is the form more commonly reported. Another area of interest pertinent to MPO expression is related to the use of anti-MPO monoclonal antibodies for the lineage assignment of acute leukemic cells, the definition of FAB MO acute myeloid leukemia, the identification of biphenotypic acute leukemias, and their distinction from acute leukemia with minimal phenotypic deviation

  7. [Iron deficiency and iron deficiency anemia are global health problems].

    Science.gov (United States)

    Dahlerup, Jens; Lindgren, Stefan; Moum, Björn

    2015-03-10

    Iron deficiency and iron deficiency anemia are global health problems leading to deterioration in patients' quality of life and more serious prognosis in patients with chronic diseases. The cause of iron deficiency and anemia is usually a combination of increased loss and decreased intestinal absorption and delivery from iron stores due to inflammation. Oral iron is first line treatment, but often hampered by intolerance. Intravenous iron is safe, and the preferred treatment in patients with chronic inflammation and bowel diseases. The goal of treatment is normalisation of hemoglobin concentration and recovery of iron stores. It is important to follow up treatment to ensure that these objectives are met and also long-term in patients with chronic iron loss and/or inflammation to avoid recurrence of anemia.

  8. Iron deficiency in blood donors

    Directory of Open Access Journals (Sweden)

    Armando Cortés

    2005-03-01

    Full Text Available Context: Blood donation results in a substantial loss of iron (200 to 250 mg at each bleeding procedure (425 to 475 ml and subsequent mobilization of iron from body stores. Recent reports have shown that body iron reserves generally are small and iron depletion is more frequent in blood donors than in non-donors. Objective: The aim of this study was to evaluate the frequency of iron deficiency in blood donors and to establish the frequency of iron deficiency in blood donors according to sex, whether they were first-time or multi-time donors. Design: From march 20 to April 5, 2004, three hundred potential blood donors from Hemocentro del Café y Tolima Grande were studied. Diagnostic tests: Using a combination of biochemical measurements of iron status: serum ferritin (RIA, ANNAR and the hemoglobin pre and post-donation (HEMOCUE Vital technology medical . Results: The frequency of iron deficiency in potential blood donors was 5%, and blood donors accepted was 5.1%; in blood donors rejected for low hemoglobin the frequency of iron deficiency was 3.7% and accepted blood donors was 1.7% in male and 12.6% in female. The frequency of iron deficiency was higher in multi-time blood donors than in first-time blood donors, but not stadistic significative. Increase nivel accepted hemoglobina in 1 g/dl no incidence in male; in female increase of 0.5 g/dl low in 25% blood donors accepted with iron deficiency, but increased rejected innecesary in 16.6% and increased is 1 g/dl low blood donors female accepted in 58% (7/12, but increased the rejected innecesary in 35.6%. Conclusions: We conclude that blood donation not is a important factor for iron deficiency in blood donors. The high frequency of blood donors with iron deficiency found in this study suggests a need for a more accurate laboratory trial, as hemoglobin or hematocrit measurement alone is not sufficient for detecting and excluding blood donors with iron deficiency without anemia, and ajustes hacia

  9. Iron deficiency and cardiovascular disease.

    Science.gov (United States)

    von Haehling, Stephan; Jankowska, Ewa A; van Veldhuisen, Dirk J; Ponikowski, Piotr; Anker, Stefan D

    2015-11-01

    Iron deficiency affects up to one-third of the world's population, and is particularly common in elderly individuals and those with certain chronic diseases. Iron excess can be detrimental in cardiovascular illness, and research has now also brought anaemia and iron deficiency into the focus of cardiovascular medicine. Data indicate that iron deficiency has detrimental effects in patients with coronary artery disease, heart failure (HF), and pulmonary hypertension, and possibly in patients undergoing cardiac surgery. Around one-third of all patients with HF, and more than one-half of patients with pulmonary hypertension, are affected by iron deficiency. Patients with HF and iron deficiency have shown symptomatic improvements from intravenous iron administration, and some evidence suggests that these improvements occur irrespective of the presence of anaemia. Improved exercise capacity has been demonstrated after iron administration in patients with pulmonary hypertension. However, to avoid iron overload and T-cell activation, it seems that recipients of cardiac transplantations should not be treated with intravenous iron preparations.

  10. Differential diagnosis of iron deficiency

    OpenAIRE

    2010-01-01

    A deficiência de ferro é considerada a patologia hematológica mais prevalente no homem. Assim, é fundamental a adequada identificação de suas causas, bem como a diferenciação com outras patologias distintas para adequada abordagem da deficiência de ferro. Neste artigo são brevemente descritas outras condições que podem cursar com anemia microcítica, tais como: talassemias, anemia de doença crônica, anemia sideroblástica e envenenamento por chumbo, patologias estas que devem ser afastadas dura...

  11. [Phosphate metabolism and iron deficiency].

    Science.gov (United States)

    Yokoyama, Keitaro

    2016-02-01

    Autosomal dominant hypophosphatemic rickets(ADHR)is caused by gain-of-function mutations in FGF23 that prevent its proteolytic cleavage. Fibroblast growth factor 23(FGF23)is a hormone that inhibits renal phosphate reabsorption and 1,25-dihydroxyvitamin D biosynthesis. Low iron status plays a role in the pathophysiology of ADHR. Iron deficiency is an environmental trigger that stimulates FGF23 expression and hypophosphatemia in ADHR. It was reported that FGF23 elevation in patients with CKD, who are often iron deficient. In patients with nondialysis-dependent CKD, treatment with ferric citrate hydrate resulted in significant reductions in serum phosphate and FGF23.

  12. Primary Carnitine (OCTN2) Deficiency Without Neonatal Carnitine Deficiency

    NARCIS (Netherlands)

    Boer, L. de; Kluijtmans, L.A.J.; Morava, E.

    2013-01-01

    Although the diagnosis of a primary carnitine deficiency is usually based on a very low level of free and total carnitine (free carnitine: 1-5 muM, normal 20-55 muM) (Longo et al. 2006), we detected a patient via newborn screening with a total carnitine level 67 % of the normal value. At the age of

  13. EFFECT OF FREE FATTY ACIDS ON LONG-CHAIN ACYL-COA SYNTHETASE 1 EXPRESSION LEVEL AND LIPID METABOLISM IN LIVER CELLS%游离脂肪酸对肝细胞ACSL1表达及相关脂代谢的影响

    Institute of Scientific and Technical Information of China (English)

    刘艳; 施文荣; 洪振丰; 郑海音; 李颖

    2013-01-01

    目的 研究游离脂肪酸(FFA)的诱导对L02肝细胞长链脂酰CoA合成酶1(ACSL1)的表达及相关代谢的影响.方法 用含不同浓度(0.2、0.4、0.8 mmol/L) FFA的培养液诱导L02细胞48 h,Western blot检测ACSL1蛋白水平,荧光定量PCR检测ACSL1 mRNA水平,比色法测定甘油三酯(TG)含量、ATP水平和培养上清FFA浓度变化,生化法测定酮体含量和培养上清葡萄糖浓度变化.结果 FFA的诱导可显著提高ACSL1蛋白表达水平(P<0.01),但对ACSL1 mRNA水平无明显影响(P>0.05),细胞内TG含量显著升高(P<0.01或P<0.05),酮体含量显著升高(P<0.05),培养上清葡萄糖消耗显著增加(P<0.01),胞内ATP水平无明显变化(P>0.05),与0.2 mmol/L、0.4 mmol/L FFA组相比,0.8 mmol/L FFA组培养上清FFA消耗显著增加(P<0.01或P<0.05).结论 FFA通过上调ACSL1蛋白表达水平致肝细胞TG蓄积.%Objective To investigate the effect of free fatty acids (FFA) on long-chain acyl-CoA synthetase l(ACSL1) expression level and lipid metabolism in L02 cells.Methods The cells were treated by FFA (0.2,0.4,0.8 mmol/L) for 48 h.ACSL1 mRNA level was measured by quantitative real-time polymerase chain reaction (PCR) and protein level by Western blotting.Cellular triglyceride (TG),ketone bodies (Ket),ATP and consumption of FFA and glucose in culture supernatant were measured.Results Compared with normal control group,treatment of L02 cells with FFA did not affect ACSL1 mRNA expression level but significantly increased ACSL1 protein expression level.TG content,Ket level and consumption of glucose in culture supernatant were significantly higher and ATP level was not affected.Compared with 0.2 and 0.4 mmol/L FFA group,the consumption of FFA in culture supernatant was significantly higher in treatment with 0.8 mmol/L FFA.Conclusion FFA induced intracellular TG accumulation by up-regulating ACSL1 protein level in L02 cells.

  14. Dopamine beta-hydroxylase deficiency

    Directory of Open Access Journals (Sweden)

    Senard Jean-Michel

    2006-03-01

    Full Text Available Abstract Dopamine beta-hydroxylase (DβH deficiency is a very rare form of primary autonomic failure characterized by a complete absence of noradrenaline and adrenaline in plasma together with increased dopamine plasma levels. The prevalence of DβH deficiency is unknown. Only a limited number of cases with this disease have been reported. DβH deficiency is mainly characterized by cardiovascular disorders and severe orthostatic hypotension. First symptoms often start during a complicated perinatal period with hypotension, muscle hypotonia, hypothermia and hypoglycemia. Children with DβH deficiency exhibit reduced ability to exercise because of blood pressure inadaptation with exertion and syncope. Symptoms usually worsen progressively during late adolescence and early adulthood with severe orthostatic hypotension, eyelid ptosis, nasal stuffiness and sexual disorders. Limitation in standing tolerance, limited ability to exercise and traumatic morbidity related to falls and syncope may represent later evolution. The syndrome is caused by heterogeneous molecular alterations of the DBH gene and is inherited in an autosomal recessive manner. Restoration of plasma noradrenaline to the normal range can be achieved by therapy with the synthetic precursor of noradrenaline, L-threo-dihydroxyphenylserine (DOPS. Oral administration of 100 to 500 mg DOPS, twice or three times daily, increases blood pressure and reverses the orthostatic intolerance.

  15. Educational paper: Primary antibody deficiencies

    NARCIS (Netherlands)

    G.J.A. Driessen (Gertjan); M. van der Burg (Mirjam)

    2011-01-01

    textabstractPrimary antibody deficiencies (PADs) are the most common primary immunodeficiencies and are characterized by a defect in the production of normal amounts of antigen-specific antibodies. PADs represent a heterogeneous spectrum of conditions, ranging from often asymptomatic selective IgA a

  16. Epigenetic Deficiencies and Replicative Stress

    DEFF Research Database (Denmark)

    Shoaib, Muhammad; Sørensen, Claus Storgaard

    2015-01-01

    Cancer cell-specific synthetic lethal interactions entail promising therapeutic possibilities. In this issue of Cancer Cell, Pfister et al. describe a synthetic lethal interaction where cancer cells deficient in H3K36me3 owing to SETD2 loss-of-function mutation are strongly sensitized to inhibiti...

  17. Deferasirox in pyruvate kinase deficiency

    OpenAIRE

    Deeren, Dries

    2008-01-01

    Deferasirox in pyruvate kinase deficiency phone: +32-51-237437 (Deeren, Dries) (Deeren, Dries) Department of Haematology, Heilig-Hartziekenhuis Roeselare-Menen vzw - Wilgenstraat 2 - B-8800 - Roeselare - BELGIUM (Deeren, Dries) BELGIUM Registration: 2008-09-10 Received: 2008-09-05 Accepted: 2008-09-10 ePublished: 2008-09-23

  18. Management of Iron Deficiency Anemia

    Science.gov (United States)

    Jimenez, Kristine; Kulnigg-Dabsch, Stefanie

    2015-01-01

    Anemia affects one-fourth of the world’s population, and iron deficiency is the predominant cause. Anemia is associated with chronic fatigue, impaired cognitive function, and diminished well-being. Patients with iron deficiency anemia of unknown etiology are frequently referred to a gastroenterologist because in the majority of cases the condition has a gastrointestinal origin. Proper management improves quality of life, alleviates the symptoms of iron deficiency, and reduces the need for blood transfusions. Treatment options include oral and intravenous iron therapy; however, the efficacy of oral iron is limited in certain gastrointestinal conditions, such as inflammatory bowel disease, celiac disease, and autoimmune gastritis. This article provides a critical summary of the diagnosis and treatment of iron deficiency anemia. In addition, it includes a management algorithm that can help the clinician determine which patients are in need of further gastrointestinal evaluation. This facilitates the identification and treatment of the underlying condition and avoids the unnecessary use of invasive methods and their associated risks. PMID:27099596

  19. Congenital β-lipoprotein deficiency

    NARCIS (Netherlands)

    Buchem, F.S.P. van; Pol, G.; Gier, J. de; Böttcher, C.J.F.; Pries, C.

    1966-01-01

    There are several degrees of β-lipoprotein deficiency. If there is no β-lipoprotein present, or if there are only traces of it, the Bassen-Kornzweig syndrome develops. A constant feature of this syndrome is disturbed fat absorption with accumulation of fat in the epithelium of intestinal mucosa and

  20. Effect of Fe additive on the hydrogenation-dehydrogenation properties of 2LiH + MgB2/2LiBH4 + MgH2 system

    Science.gov (United States)

    Puszkiel, J. A.; Gennari, F. C.; Larochette, P. Arneodo; Ramallo-López, J. M.; Vainio, U.; Karimi, F.; Pranzas, P. K.; Troiani, H.; Pistidda, C.; Jepsen, J.; Tolkiehn, M.; Welter, E.; Klassen, T.; Bellosta von Colbe, J.; Dornheim, M.

    2015-06-01

    Lithium reactive hydride composite 2LiBH4 + MgH2 (Li-RHC) has been lately investigated owing to its potential as hydrogen storage medium for mobile applications. However, the main problem associated with this material is its sluggish kinetic behavior. Thus, aiming to improve the kinetic properties, in the present work the effect of the addition of Fe to Li-RHC is investigated. The addition of Fe lowers the starting decomposition temperature of Li-RHC about 30 °C and leads to a considerably faster isothermal dehydrogenation rate during the first hydrogen sorption cycle. Upon hydrogenation, MgH2 and LiBH4 are formed whereas Fe appears not to take part in any reaction. Upon the first dehydrogenation, the formation of nanocrystalline, well distributed FeB reduces the overall hydrogen storage capacity of the system. Throughout cycling, the agglomeration of FeB particles causes a kinetic deterioration. An analysis of the hydrogen kinetic mechanism during cycling shows that the hydrogenation and dehydrogenation behavior is influenced by the activity of FeB as heterogeneous nucleation center for MgB2 and its non-homogenous distribution in the Li-RHC matrix.

  1. Identifying Causes of Job Performance Deficiencies.

    Science.gov (United States)

    Herem, Maynard A.

    1979-01-01

    A model to guide the search for types of performance deficiencies is set forth within the general framework of systems theory. Five types of problems, singly or in combination, are discussed as causes of deficiencies. (Author)

  2. Genetics Home Reference: congenital leptin deficiency

    Science.gov (United States)

    ... Obesity? National Institute of Diabetes and Digestive and Kidney Diseases: Active at Any Size! Educational Resources (6 links) Centers for Disease Control and Prevention: Obesity and Genetics MalaCards: congenital leptin deficiency Orphanet: Obesity due to congenital leptin deficiency ...

  3. Genetics Home Reference: protein S deficiency

    Science.gov (United States)

    ... my area? Other Names for This Condition hereditary thrombophilia due to protein S deficiency Related Information How are ... Merck Manual Home Edition for Patients and Caregivers: Thrombophilia Orphanet: Hereditary thrombophilia due to congenital protein S deficiency ...

  4. Genetics Home Reference: corticosterone methyloxidase deficiency

    Science.gov (United States)

    ... levels of potassium in the blood (hyponatremia and hyperkalemia, respectively). Individuals with corticosterone methyloxidase deficiency can also ... acid in the blood (metabolic acidosis). The hyponatremia, hyperkalemia, and metabolic acidosis associated with corticosterone methyloxidase deficiency ...

  5. Cobalamin deficiency, hyperhomocysteinemia, and dementia

    Directory of Open Access Journals (Sweden)

    Steven F Werder

    2010-04-01

    Full Text Available Steven F Werder1,21Kansas University School of Medicine – Wichita, Wichita, KS, USA; 2Community Health Center of Southeast Kansas, Pittsburg, KS, USAIntroduction: Although consensus guidelines recommend checking serum B12 in patients with dementia, clinicians are often faced with various questions: (1 Which patients should be tested? (2 What test should be ordered? (3 How are inferences made from such testing? (4 In addition to serum B12, should other tests be ordered? (5 Is B12 deficiency compatible with dementia of the Alzheimer’s type? (6 What is to be expected from treatment? (7 How is B12 deficiency treated?Methods: On January 31st, 2009, a Medline search was performed revealing 1,627 citations related to cobalamin deficiency, hyperhomocysteinemia, and dementia. After limiting the search terms, all abstracts and/or articles and other references were categorized into six major groups (general, biochemistry, manifestations, associations and risks, evaluation, and treatment and then reviewed in answering the above questions.Results: The six major groups above are described in detail. Seventy-five key studies, series, and clinical trials were identified. Evidence-based suggestions for patient management were developed.Discussion: Evidence is convincing that hyperhomocysteinemia, with or without hypovitaminosis B12, is a risk factor for dementia. In the absence of hyperhomocysteinemia, evidence is less convincing that hypovitaminosis B12 is a risk factor for dementia. B12 deficiency manifestations are variable and include abnormal psychiatric, neurological, gastrointestinal, and hematological findings. Radiological images of individuals with hyperhomocysteinemia frequently demonstrate leukoaraiosis. Assessing serum B12 and treatment of B12 deficiency is crucial for those cases in which pernicious anemia is suspected and may be useful for mild cognitive impairment and mild to moderate dementia. The serum B12 level is the standard initial test

  6. Contamination Effects on Improving the Hydrogenation/Dehydrogenation Kinetics of Binary Magnesium Hydride/Titanium Carbide Systems Prepared by Reactive Ball Milling

    Directory of Open Access Journals (Sweden)

    M. Sherif El-Eskandarany

    2015-10-01

    Full Text Available Ultrafine MgH2 nanocrystalline powders were prepared by reactive ball milling of elemental Mg powders after 200 h of high-energy ball milling under a hydrogen gas pressure of 50 bar. The as-prepared metal hydride powders were contaminated with 2.2 wt. % of FeCr-stainless steel that was introduced to the powders upon using stainless steel milling tools made of the same alloy. The as-synthesized MgH2 was doped with previously prepared TiC nanopowders, which were contaminated with 2.4 wt. % FeCr (materials of the milling media, and then ball milled under hydrogen gas atmosphere for 50 h. The results related to the morphological examinations of the fabricated nanocomposite powders beyond the micro-and nano-levels showed excellent distributions of 5.2 wt. % TiC/4.6 wt. % FeCr dispersoids embedded into the fine host matrix of MgH2 powders. The as-fabricated nanocomposite MgH2/5.2 wt. % TiC/4.6 wt. % FeCr powders possessed superior hydrogenation/dehydrogenation characteristics, suggested by the low value of the activation energy (97.74 kJ/mol, and the short time required for achieving a complete absorption (6.6 min and desorption (8.4 min of 5.51 wt. % H2 at a moderate temperature of 275 C under a hydrogen gas pressure ranging from 100 mbar to 8 bar. van’t Hoff approach was used to calculate the enthalpy (DH and entropy (DS of hydrogenation for MgH2, which was found to be 72.74 kJ/mol and 112.79 J/mol H2/K, respectively. Moreover, van’t Hoff method was employed to calculate the DH and DS of dehydrogenation, which was found to be 76.76 kJ/mol and 119.15 J/mol H2/K, respectively. This new nanocomposite system possessed excellent absorption/desorption cyclability of 696 complete cycles, achieved in a cyclic-life-time of 682 h.

  7. Cobalamin deficiency in children: A literature review

    OpenAIRE

    Moen, Synne Helland

    2013-01-01

    Objective: The aim of this review is to present cobalamin deficiency in children with a specific focus on infants. Background: Cobalamin deficiency is caused by inadequate intake, malabsorption or inborn errors of vitamin B12 metabolism. Cobalamin deficiency in infants is usually caused by deficiency in the mother. There is often a diagnostic delay among infants because the most frequent symptoms are unspecific, e.g., developmental delay, apathy, hypotonia, anorexia and failure to thrive. Chi...

  8. Iron-induced nickel deficiency in pecan

    Science.gov (United States)

    Economic loss due to nickel (Ni) deficiency can occur in horticultural and agronomic crops. This study assesses impact of excessive iron (Fe) on expression of Ni deficiency in pecan [Carya illinoinensis (Wangenh.) K. Koch]. Field and greenhouse experiments found Ni deficiency to be inducible by ei...

  9. Iron Deficiency in Autism and Asperger Syndrome.

    Science.gov (United States)

    Latif, A.; Heinz, P.; Cook, R.

    2002-01-01

    Retrospective analysis of the full blood count and, when available, serum ferritin measurements of 96 children (52 with autism and 44 with Asperger syndrome) found six autistic children had iron deficiency and 12 of the 23 autistic children with serum ferritin measures were iron deficient. Far fewer Asperger children were iron deficient. Results…

  10. Iron deficiency anemia in pregnancy.

    Science.gov (United States)

    Di Renzo, Gian Carlo; Spano, Filippo; Giardina, Irene; Brillo, Eleonora; Clerici, Graziano; Roura, Luis Cabero

    2015-11-01

    Anemia is the most frequent derailment of physiology in the world throughout the life of a woman. It is a serious condition in countries that are industrialized and in countries with poor resources. The main purpose of this manuscript is to give the right concern of anemia in pregnancy. The most common causes of anemia are poor nutrition, iron deficiencies, micronutrients deficiencies including folic acid, vitamin A and vitamin B12, diseases like malaria, hookworm infestation and schistosomiasis, HIV infection and genetically inherited hemoglobinopathies such as thalassemia. Depending on the severity and duration of anemia and the stage of gestation, there could be different adverse effects including low birth weight and preterm delivery. Treatment of mild anemia prevents more severe forms of anemia, strictly associated with increased risk of fetal-maternal mortality and morbidity.

  11. Vitamin D deficiency in Europe

    DEFF Research Database (Denmark)

    Cashman, Kevin D.; Dowling, Kirsten G; Škrabáková, Zuzana

    2016-01-01

    BACKGROUND: Vitamin D deficiency has been described as being pandemic, but serum 25-hydroxyvitamin D [25(OH)D] distribution data for the European Union are of very variable quality. The NIH-led international Vitamin D Standardization Program (VDSP) has developed protocols for standardizing existing...... 25(OH)D values from national health/nutrition surveys. OBJECTIVE: This study applied VDSP protocols to serum 25(OH)D data from representative childhood/teenage and adult/older adult European populations, representing a sizable geographical footprint, to better quantify the prevalence of vitamin D...... sera. These data were combined with standardized serum 25(OH)D data from 4 previously standardized studies (for a total n = 55,844). Prevalence estimates of vitamin D deficiency [using various serum 25(OH)D thresholds] were generated on the basis of standardized 25(OH)D data. RESULTS: An overall pooled...

  12. DNA repair deficiency in neurodegeneration

    DEFF Research Database (Denmark)

    Jeppesen, Dennis Kjølhede; Bohr, Vilhelm A; Stevnsner, Tinna V.

    2011-01-01

    : homologous recombination and non-homologous end-joining. Ataxia telangiectasia and related disorders with defects in these pathways illustrate that such defects can lead to early childhood neurodegeneration. Aging is a risk factor for neurodegeneration and accumulation of oxidative mitochondrial DNA damage......Deficiency in repair of nuclear and mitochondrial DNA damage has been linked to several neurodegenerative disorders. Many recent experimental results indicate that the post-mitotic neurons are particularly prone to accumulation of unrepaired DNA lesions potentially leading to progressive...... neurodegeneration. Nucleotide excision repair is the cellular pathway responsible for removing helix-distorting DNA damage and deficiency in such repair is found in a number of diseases with neurodegenerative phenotypes, including Xeroderma Pigmentosum and Cockayne syndrome. The main pathway for repairing oxidative...

  13. Molecular Genetics of Lactase Deficiencies

    OpenAIRE

    Kuokkanen, Mikko

    2006-01-01

    Congenital lactase deficiency (CLD) (MIM 223000) is a rare autosomal recessive gastrointestinal disorder characterized by watery diarrhea in infants fed with breast milk or other lactose-containing formulas. The CLD locus was previously assigned by linkage and linkage disequilibrium analyses on 2q21 in 19 Finnish families. In this study, the molecular background of this disorder is reported. The CLD locus was refined in 32 CLD patients in 24 families by using microsatellite and single nucleot...

  14. Iron refractory iron deficiency anemia

    OpenAIRE

    De Falco, Luigia; Sanchez, Mayka; Silvestri, Laura; Kannengiesser, Caroline; Muckenthaler, Martina U; Iolascon, Achille; Gouya, Laurent; Camaschella, Clara; Beaumont, Carole

    2013-01-01

    Iron refractory iron deficiency anemia is a hereditary recessive anemia due to a defect in the TMPRSS6 gene encoding Matriptase-2. This protein is a transmembrane serine protease that plays an essential role in down-regulating hepcidin, the key regulator of iron homeostasis. Hallmarks of this disease are microcytic hypochromic anemia, low transferrin saturation and normal/high serum hepcidin values. The anemia appears in the post-natal period, although in some cases it is only diagnosed in ad...

  15. Congenital deficiency of factor VII.

    Science.gov (United States)

    Sikka, M; Gomber, S; Madan, N; Rusia, U; Sharma, S

    1996-01-01

    A case of congenital factor VII deficiency in a five-year-old child is reported. The patient, born of a non-consanguineous marriage, presented with repeated bouts of epistaxis since childhood. The prothrombin time (PT) was markedly prolonged with a normal bleeding time (BT), partial thromboplastin time with Kaolin (PTTK) and platelet count. The patient has been on follow up for the last four years and is doing apparently well.

  16. Mitochondrial cytochrome c oxidase deficiency.

    Science.gov (United States)

    Rak, Malgorzata; Bénit, Paule; Chrétien, Dominique; Bouchereau, Juliette; Schiff, Manuel; El-Khoury, Riyad; Tzagoloff, Alexander; Rustin, Pierre

    2016-03-01

    As with other mitochondrial respiratory chain components, marked clinical and genetic heterogeneity is observed in patients with a cytochrome c oxidase deficiency. This constitutes a considerable diagnostic challenge and raises a number of puzzling questions. So far, pathological mutations have been reported in more than 30 genes, in both mitochondrial and nuclear DNA, affecting either structural subunits of the enzyme or proteins involved in its biogenesis. In this review, we discuss the possible causes of the discrepancy between the spectacular advances made in the identification of the molecular bases of cytochrome oxidase deficiency and the lack of any efficient treatment in diseases resulting from such deficiencies. This brings back many unsolved questions related to the frequent delay of clinical manifestation, variable course and severity, and tissue-involvement often associated with these diseases. In this context, we stress the importance of studying different models of these diseases, but also discuss the limitations encountered in most available disease models. In the future, with the possible exception of replacement therapy using genes, cells or organs, a better understanding of underlying mechanism(s) of these mitochondrial diseases is presumably required to develop efficient therapy.

  17. [Iodine deficiency in cardiovascular diseases].

    Science.gov (United States)

    Molnár, I; Magyari, M; Stief, L

    1998-08-30

    The thyroid hormone deficiency on cardiovascular function can be characterized with decreased myocardial contractility and increased peripheral vascular resistance as well as with the changes in lipid metabolism. 42 patients with cardiovascular disease (mean age 65 +/- 13 yr, 16 males) were investigated if iodine insufficiency can play a role as a risk factor for the cardiovascular diseases. The patients were divided in 5 subgroups on the ground of the presence of hypertension, congestive heart failure, cardiomyopathy, coronary disfunction and arrhythmia. Urine iodine concentration (5.29 +/- 4.52 micrograms/dl) was detected with Sandell-Kolthoff colorimetric reaction. The most decreased urine iodine concentration was detected in the subgroups with arrhythmia and congestive heart failure (4.7 +/- 4.94 micrograms/dl and 4.9 +/- 4.81 micrograms/dl, respectively). An elevated TSH level was found by 3 patients (5.3 +/- 1.4 mlU/l). An elevation in lipid metabolism (cholesterol, triglyceride) associated with all subgroups without arrhythmia. In conclusion, the occurrence of iodine deficiency in cardiovascular disease is frequent. Iodine supplementation might prevent the worsing effect of iodine deficiency on cardiovascular disease.

  18. Zinc Deficiency in Humans and its Amelioration

    OpenAIRE

    Yashbir Singh Shivay

    2015-01-01

    Zinc (Zn) deficiency in humans has recently received considerable attention. Global mortality in children under 5 years of age in 2004 due to Zn deficiency was estimated at 4,53,207 as against 6,66,771 for vitamin A deficiency; 20,854 for iron deficiency and 3,619 for iodine deficiency. In humans 2800-3000 proteins contain Zn prosthetic group and Zn is an integral component of zinc finger prints that regulate DNA transcription. Zinc is a Type-2 nutrient, which means that its concentration in ...

  19. A study by electrical conductivity measurements of the semiconductive and redox properties of Nb-doped NiO catalysts in correlation with the oxidative dehydrogenation of ethane.

    Science.gov (United States)

    Popescu, Ionel; Skoufa, Zinovia; Heracleous, Eleni; Lemonidou, Angeliki; Marcu, Ioan-Cezar

    2015-03-28

    Nb-doped nickel oxides with Nb contents in the range from 1 to 20% and, for comparison, pure NiO, were characterized using in situ electrical conductivity measurements in correlation with their catalytic performances for the oxidative dehydrogenation (ODH) of ethane into ethylene. Their electrical conductivity was studied as a function of temperature and oxygen partial pressure and was followed with time during sequential exposures to air, ethane-air mixture (reaction mixture) and pure ethane in conditions similar to those of catalysis. All the oxides were p-type semiconductors under air. Their electrical conductivity in the reaction temperature range decreased in the following order: NiO > Nb(1)NiO > Nb(5)NiO > Nb(10)NiO > Nb(15)NiO > Nb(20)NiO. This correlates well with the catalytic activity expressed as the intrinsic rate of ethane consumption. All the catalysts were partially reduced under the reaction mixture in the reaction temperature range, an inverse correlation between their conductivity in these conditions and the ODH selectivity being observed. The ODH reaction of ethane takes place via a heterogeneous redox mechanism involving the surface lattice O(-) species.

  20. Effect of CO{sub 2}-admixture on the catalytic performance of Ni-Nb-M-O catalysts in oxidative dehydrogenation of ethane to ethylene

    Energy Technology Data Exchange (ETDEWEB)

    Qiao, A.; Kalevaru, V.N.; Martin, A. [Rostock Univ. (Germany). Leibniz-Institut fuer Katalyse e.V.; Hari Kumar, A. Sri; Lingaiah, N.; Prasad, P.S. Sai [Indian Institute of Chemical Technology, Hyderabad (India). Inorganic and Physical Chemistry Div.

    2012-07-01

    In this work, we report the synthesis, characterization and application of Ni-Nb-M-O catalysts with different promoters (M = Cr, Mo, W) for the oxidative dehydrogenation (ODH) of ethane to ethylene. Ni:Nb:M ratio was kept at 1:0.176:0.1 (atomic ratio). The catalysts were calcined at 450 C/5h/air. Catalytic tests were carried out in a fixed bed quartz reactor in the temperature range from 300 to 450 C, with a fixed W/F (1.02 g/cm{sup 3} . s{sup -1}) but with changing mole ratios of C{sub 2}H{sub 6}:O{sub 2}:CO{sub 2}:N{sub 2} (1:0-1.4:1.4-0:2). The product analysis was made off-line using GC equipped with FID. It is evident that the CO{sub 2}-admixture to the reactant feed caused a slight decrease in the conversion of ethane but considerably improved the selectivity of ethylene. Among the three promoters of the same group applied, Cr exhibited superior performance compared to other two. This means increase in d-character of transition metal (i.e. from 3d to 5d) has shown an adverse effect on the conversion of ethane and selectivity of ethylene. (orig.)

  1. Effect of gallium,aluminium,and chromium on silica supported V-Mg-O catalysts during oxidative dehydrogenation of propane:Kinetic study

    Institute of Scientific and Technical Information of China (English)

    B.Ravi Kumar; Rajeev Kumar

    2008-01-01

    The oxidative dehydrogenation(ODH)of propane was conducted on gallium,aluminum.and chromium doped Si30VMgO catalysts.On doping,the concentrations of the phases responsible for the activity and selectivity increased in their concentrations.The reaction studies were conducted in a tubular steel reactor at temperatures of 753,783,813.and 843 K and atmospheric pressure.The total flow rates of the feed were chosen as 30,40,50,and 60 ml/min.The propane to oxygen ratios were chosen at 1:1,2:1,and 3:1,respectively.The effect of various dopants on the activity and selectivity of the catalysts was studied.Deactivation studies were conducted over all the catalysts.The kinetic data were analyzed in terms of power law models and Langmuir-Hinshelwood(LH)models.The kinetic data results were analyzed by comparing the effect of dopants.Statistical model discrimination was done for the proposed models.AIC and BIC criteria were used for discrimination of the models.

  2. Catalytic amine-borane dehydrogenation by a PCP-pincer palladium complex: a combined experimental and DFT analysis of the reaction mechanism.

    Science.gov (United States)

    Rossin, Andrea; Bottari, Giovanni; Lozano-Vila, Ana M; Paneque, Margarita; Peruzzini, Maurizio; Rossi, Andrea; Zanobini, Fabrizio

    2013-03-14

    Catalytic dehydrogenation of ammonia-borane (NH(3)·BH(3), AB) and dimethylamine borane (NHMe(2)·BH(3), DMAB) by the Pd(II) complex [((tBu)PCP)Pd(H(2)O)]PF(6) [(tBu)PCP = 2,6-C(6)H(3)(CH(2)P(t)Bu(2))(2)] leads to oligomerization and formation of spent fuels of general formula cyclo-[BH(2)-NR(2)](n) (n = 2,3; R = H, Me) as reaction byproducts, while one equivalent of H(2) is released per amine-borane equivalent. The processes were followed through multinuclear ((31)P, (1)H, (11)B) variable temperature NMR spectroscopy; kinetic measurements on the hydrogen production rate and the relative rate constants were also carried out. One non-hydridic intermediate could be detected at low temperature, whose chemical nature was explored through a DFT modeling of the reaction mechanism, at the M06//6-31+G(d,p) computational level. The computational output was of help to propose a reliable mechanistic picture of the process.

  3. V{sub 2}O{sub 5}-ZrO{sub 2} catalysts for the oxidative dehydrogenation of propane - influence of the niobium oxide doping

    Energy Technology Data Exchange (ETDEWEB)

    Albrecht, S.; Hallmeier, K.H.; Wendt, G. [Leipzig Univ. (Germany). Fakultaet fuer Chemie und Mineralogie; Lippold, G. [Leipzig Univ. (Germany). Fakultaet fuer Physik und Geowissenschaften

    1998-12-31

    The oxidative dehydrogenation (ODH) of light alkanes is an alternative way for the production of olefins. A wide variety of catalytic systems has been investigated. Vanadium oxide based catalysts were described in the literature as effective catalysts for the ODH of propane. The catalytic activity and selectivity depend on the kind of support material, the kind of dopants and the formation of complex metal oxide phases. In recent papers it was claimed that both orthovanadate and/or pyrovanadate species are selective for the ODH of propane. Niobia based materials were investigated as catalysts for acidic and selective oxidation type reactions. In the ODH of propane niobia exhibited a high selectivity to propene but the conversion of propane was low. V{sub 2}O{sub 5}-Nb{sub 2}O{sub 5} catalysts proved to be catalytically active and selective and showed no formation of oxygenates. In the present study the influence of the niobia dopant of the catalytic properties of V{sub 2}O{sub 5}-ZrO{sub 2} catalysts in the ODH of propane was examined. The structural and textural properties of the catalysts were investigated using several methods. (orig.)

  4. Mechanical and Thermal Dehydrogenation of the Mechano-Chemically Synthesized Calcium Alanate (Ca(AlH42 and Lithium Chloride (LiCl Composite

    Directory of Open Access Journals (Sweden)

    Robert A. Varin

    2015-06-01

    Full Text Available LiAlH4 and CaCl2 were employed for mechano-chemical activation synthesis (MCAS of Ca(AlH42 and LiCl hydride composite. After short ball milling time, their X-ray diffraction (XRD peaks are clearly observed. After ball milling for a longer duration than 0.5 h, the CaAlH5 diffraction peaks are observed which indicates that Ca(AlH42 starts decomposing during ball milling into CaAlH5+Al+1.5H2. It is estimated that less than 1 wt % H2 was mechanically dehydrogenated in association with decomposition reaction. After 2.5 h of ball milling, no Ca(AlH42 diffraction peaks were observed on XRD patterns which suggests that Ca(AlH42 was decomposed. Thermal behavior of ball milled powders, which was investigated by thermal gravimetric analysis (TGA and differential scanning calorimetry (DSC, indicates that a certain fraction of Ca(AlH42 could have been disordered/amorphized during ball milling being undetectable by XRD. The apparent activation energy for the decomposition of Ca(AlH42 and CaAlH5 equals 135 kJ/mol and 183 kJ/mol, respectively.

  5. Photofragmentation of the closo-carboranes part II: VUV assisted dehydrogenation in the closo-carboranes and semiconducting B10C2H(x) films.

    Science.gov (United States)

    Rühl, Eckart; Riehs, Norman F; Behera, Swayambhu; Wilks, Justin; Liu, Jing; Jochims, H-W; Caruso, Anthony N; Boag, Neil M; Kelber, Jeffry A; Dowben, Peter A

    2010-07-15

    The dehydrogenation of semiconducting boron carbide (B(10)C(2)H(x)) films as well as the three closo-carborane isomers of dicarbadodecaborane (C(2)B(10)H(12)) and two isomers of the corresponding closo-phosphacarborane (PCB(10)H(11)) all appear to be very similar. Photoionization mass spectrometry studies at near-threshold gas phase photoionization indicate that the preferred pathway for dissociation of the parent cation species (C(2)B(10)H(10)(+) or PCB(10)H(9)(+)) is, in all cases, the loss of H(2). Ab initio density functional theory (DFT) calculations indicate that energetically preferred sites for exopolyhedral hydrogen (B-H) bond dissociation are in all cases at B atoms opposite the C atoms in the parent cage molecule. The site of photodissociation of hydrogen from semiconducting boron carbide (B(10)C(2)H(x)) films, fabricated by plasma-enhanced chemical vapor deposition, is a cage boron atom that can bond to nitrogen upon exposure to VUV light in the presence of NH(3). Shifts in core level binding energies due to nitrogen bond formation indicate that B-N bond formation occurs only at B atoms bound to other boron atoms (B-B sites) and not at B-C sites or at C sites, in agreement with gas phase results.

  6. The effect of mixed HCl-KCl competitive adsorbate on Pt adsorption and catalytic properties of Pt-Sn/Al2O3 catalysts in propane dehydrogenation

    Science.gov (United States)

    Zangeneh, Farnaz Tahriri; Taeb, Abbas; Gholivand, Khodayar; Sahebdelfar, Saeed

    2015-12-01

    The effect of competitive adsorbate concentration and combination on the adsorption of H2PtCl6 onto γ-Al2O3 in the preparation and performance of PtSnK/γ-Al2O3 catalyst for propane dehydrogenation was investigated. The catalysts were prepared by sequential impregnation of Sn and Pt precursors. The effect of competitor concentration on Pt adsorption was studied by using hydrochloric acid (0.1-0.3 M) and the effect of pH was studied by using KCl/HCl mixtures at constant (0.1 M) total chloride ion concentration. The catalysts were characterized by nitrogen adsorption/desorption, XRD, XRF, SEM and CO chemisorption. The catalytic performance tests were carried out in a fixed-bed quartz reactor under kinetic controlled condition for proper catalyst screening. It was found that the corrosive competitor HCl could be partially substituted with KCl without appreciable impact on catalyst performance with the advantage of lower acid attack on the support and reduced leaching of the deposited tin. A model based on initial concentration and uptake of the adsorbates was developed to obtain the adsorption parameters. Values of 890 μmol/g and 600 lit/mol were obtained for adsorption site concentration of the tin-impregnated support and equilibrium constant for Pt adsorption, respectively, for HCl concentration range of 0.1-0.3 M.

  7. Preparation of Highly Active Pt-K/γ-AI203 Catalyst for 0-Phenylphenol Synthesis from 0-Cyclohexenyl-cyclohexanone Dehydrogenation

    Institute of Scientific and Technical Information of China (English)

    DING Jie-lian; LIN Ling; XU Jian-dong; ZENG Chong-yu

    2008-01-01

    0.5%Pt-K/y-Al2O3 catalysts for the synthesis of 0-phenylphenol(OPP) from 0-cyclohexenyl-cyciohexanone (dimer) dehydrogenation were prepared by means of a two subsequent impregnation method.The effects of catalyst preparation parameters,such as K promoters,calcination,and reduction conditions,were investigated.The results showed that the addition of K2SO4 to Pt/y-Al2O3 catalyst notably promoted the selectivity of OPP,and its optimum content was found to be 6% in mass fraction.The higher activity was obtained when Pt/y-Al2O3 catalyst was calcined in nitrogen atmosphere at 400-500℃ and then reduced at the same temperature for 3 h in hydrogen atmosphere.The conversion of the dimer and the selectivity of OPP were always above 99% and 90%,respectively,over 0.5%Pt-6% K2SO4/γ-Al2O3 catalyst during the pilot scale test of 8000 h.

  8. One-pot synthesis of core-shell Cu@SiO2 nanospheres and their catalysis for hydrolytic dehydrogenation of ammonia borane and hydrazine borane

    Science.gov (United States)

    Yao, Qilu; Lu, Zhang-Hui; Zhang, Zhujun; Chen, Xiangshu; Lan, Yaqian

    2014-12-01

    Ultrafine copper nanoparticles (Cu NPs) within porous silica nanospheres (Cu@SiO2) were prepared via a simple one-pot synthetic route in a reverse micelle system and characterized by SEM, TEM, EDX, XRD, N2 adsorption-desorption, CO-TPD, XPS, and ICP methods. The characterized results show that ultrafine Cu NPs with diameter of around 2 nm are effectively embedded in the center of well-proportioned spherical SiO2 NPs of about 25 nm in diameter. Compared to commercial SiO2 supported Cu NPs, SiO2 nanospheres supported Cu NPs, and free Cu NPs, the synthesized core-shell nanospheres Cu@SiO2 exhibit a superior catalytic activity for the hydrolytic dehydrogenation of ammonia borane (AB, NH3BH3) and hydrazine borane (HB, N2H4BH3) under ambient atmosphere at room temperature. The turnover frequencies (TOF) for the hydrolysis of AB and HB in the presence of Cu@SiO2 nanospheres were measured to be 3.24 and 7.58 mol H2 (mol Cu min)-1, respectively, relatively high values for Cu nanocatalysts in the same reaction. In addition, the recycle tests show that the Cu@SiO2 nanospheres are still highly active in the hydrolysis of AB and HB, preserving 90 and 85% of their initial catalytic activity even after ten recycles, respectively.

  9. Deactivation of a mixed oxide catalyst of Mo-V-Te-Nb-O composition in the reaction of oxidative ethane dehydrogenation

    Science.gov (United States)

    Mishanin, I. I.; Kalenchuk, A. N.; Maslakov, K. I.; Lunin, V. V.; Koklin, A. E.; Finashina, E. D.; Bogdan, V. I.

    2016-06-01

    The operational stability of a mixed oxide catalyst of Mo-V-Te-Nb-O composition in the oxidative dehydrogenation of ethane (ratio of C2H6: O2 = 3: 1) is studied in a flow reactor at temperatures of 340-400°C, a pressure of 1 atm, and a WHSV of the feed mixture of 800 h-1. It is found that the selectivity toward ethylene is 98% at 340°C, but the conversion of ethane at this temperature is only 6%; when the temperature is raised to 400°C, the conversion of ethane is increased to 37%, while the selectivity toward ethylene is reduced to 85%. Using physical and chemical means (XPS, SEM), it is found that the lack of oxidant in the reaction mixture leads to irreversible changes in the catalyst, i.e., reduced selectivity and activity. Raising the reaction temperature to 400°C allows the reduction of tellurium by ethane, from the +6 oxidation state to the zerovalent state, with its subsequent sublimation and the destruction of the catalytically active and selective phase; in its characteristics, the catalyst becomes similar to the Mo-V-Nb-O system containing no tellurium.

  10. Catalytic properties of the VO x /Ce0.46Zr0.54O2 oxide system in the oxidative dehydrogenation of propane

    Science.gov (United States)

    Turakulova, A. O.; Kharlanov, A. N.; Levanov, A. V.; Isaikina, O. Ya.; Lunin, V. V.

    2017-01-01

    Ce0.46Zr0.54O2 solid solution prepared using a cellulose template was employed as a carrier for vanadium catalysts of the oxidative dehydrogenation of propane. The properties of VO x /Ce0.46Zr0.54O2 catalyst (5 wt % vanadium) are compared with the properties of the neat support. The carrier and catalyst are studied by means of BET, SEM, DTA, XRD, and Raman spectroscopy. It is shown that the CeVO4 phase responsible for the ODH process is formed upon interaction between vanadate ions and cerium ions on the surface of the solid solution. The catalytic properties of the catalyst and the support are studied in the propane oxidation reaction at temperatures of 450 and 500°C with pulse feeding of the reagent. It is found that the complete oxidation of propane occurs on the support with formation of CO2 and H2O. Three products (propene, CO2, and H2O) form in the presence of the vanadium catalyst. It is suggested that there are two types of catalytic centers on the catalyst's surface. It is concluded that the centers responsible for the complete oxidation of propane are concentrated mainly on the carrier, while the centers responsible for propane ODH are on the CeVO4.

  11. Deficiencies in the Management of Iron Deficiency Anemia During Childhood.

    Science.gov (United States)

    Powers, Jacquelyn M; Daniel, Catherine L; McCavit, Timothy L; Buchanan, George R

    2016-04-01

    Limited high-quality evidence supports the management of iron deficiency anemia (IDA). To assess our institutional performance in this area, we retrospectively reviewed IDA treatment practices in 195 consecutive children referred to our center from 2006 to mid-2010. The majority of children were ≤4 years old (64%) and had nutritional IDA (74%). In 11- to 18-year-old patients (31%), the primary etiology was menorrhagia (42%). Many were referred directly to the emergency department and/or prescribed iron doses outside the recommended range. Poor medication adherence and being lost-to-follow-up were common. Substantial improvements are required in the management of IDA.

  12. Primary Carnitine (OCTN2) Deficiency Without Neonatal Carnitine Deficiency

    OpenAIRE

    Boer, L.; Kluijtmans, L.A.J.; Morava, E.

    2012-01-01

    Although the diagnosis of a primary carnitine deficiency is usually based on a very low level of free and total carnitine (free carnitine: 1–5 μM, normal 20–55 μM) (Longo et al. 2006), we detected a patient via newborn screening with a total carnitine level 67 % of the normal value. At the age of 1 year, after interruption of carnitine supplementation for a 4-week period the carnitine profile was assessed and the free carnitine level had dropped to 10.4 μmol/l (normal: 20–55 μM) and total car...

  13. Skin wound healing in MMP2-deficient and MMP2 / plasminogen double-deficient mice

    DEFF Research Database (Denmark)

    Frøssing, Signe; Rønø, Birgitte; Hald, Andreas;

    2010-01-01

    -sensitive MMPs during wound healing. To address whether MMP2 is accountable for the galardin-induced healing deficiency in wildtype and Plg-deficient mice, incisional skin wounds were generated in MMP2 single-deficient mice and in MMP2/Plg double-deficient mice and followed until healed. Alternatively, tissue...... was isolated 7 days post wounding for histological and biochemical analyses. No difference was found in the time from wounding to overt gross restoration of the epidermal surface between MMP2-deficient and wildtype control littermate mice. MMP2/Plg double-deficient mice were viable and fertile, and displayed...... an unchallenged general phenotype resembling that of Plg-deficient mice, including development of rectal prolapses. MMP2/Plg double-deficient mice displayed a slight increase in the wound length throughout the healing period compared with Plg-deficient mice. However, the overall time to complete healing...

  14. Alcoholic Myelopathy and Nutritional Deficiency

    Science.gov (United States)

    Koike, Haruki; Nakamura, Tomohiko; Ikeda, Shohei; Takahashi, Mie; Kawagashira, Yuichi; Iijima, Masahiro; Katsuno, Masahisa; Sobue, Gen

    2017-01-01

    A patient with chronic alcoholism presented with myelopathy and low serum folate and cobalamin levels. A 42-year-old alcoholic man had gait disturbance for 4 months. A neurological examination revealed marked spasticity with increased deep tendon reflexes and extensor plantar responses of the lower limbs. His cobalamin level was decreased and his serum folate level was particularly low. His plasma ammonia level was not increased. Abstinence and folic acid and cobalamin supplementation stopped the progression of his neurological deficits. This case indicates that nutritional deficiency should be monitored closely in patients with chronic alcoholism who present with myelopathy. PMID:28049986

  15. Muscle phosphoglycerate mutase deficiency revisited

    DEFF Research Database (Denmark)

    Naini, Ali; Toscano, Antonio; Musumeci, Olimpia;

    2009-01-01

    storage disease type X and novel mutations in the gene encoding the muscle subunit of PGAM (PGAM2). DESIGN: Clinical, pathological, biochemical, and molecular analyses. SETTING: Tertiary care university hospitals and academic institutions. Patients A 37-year-old Danish man of Pakistani origin who had...... PGAM deficiency, and molecular studies revealed 2 novel homozygous mutations, a nonsense mutation and a single nucleotide deletion. Pathological studies of muscle showed mild glycogen accumulation but prominent tubular aggregates in both patients. CONCLUSIONS: We found that glycogen storage disease...

  16. Vitamin D deficiency and stroke

    Directory of Open Access Journals (Sweden)

    2012-12-01

    Full Text Available Vitamin D comprises a group of fat-soluble pro-hormones, obtained from sun exposure, food, and supplements, and it must undergo two hydroxylation reactions to be activated in the body. Several studies have shown the role of vitamin D in mineral metabolism regulation, especially calcium, phosphorus, and bone metabolism. Some factors such as inadequate vitamin intake and liver or kidney disorders can lead to vitamin D deficiency. Furthermore, vitamin D malnutrition may also be linked to susceptibility to chronic diseases such as heart failure, peripheral artery disease, high blood pressure, cognitive impairment including foggy brain and memory loss, and autoimmune diseases including diabetes type I. Recent research has revealed that low levels of vitamin D increase the risk of cardiovascular-related morbidity (Sato et al., 2004 and mortality (Pilz et al., 2008. Also, hypertension contributes to a reduction in bone mineral density and increase in the incidence of stroke and death. This article reviews the function and physiology of vitamin D and examines the effects of vitamin D deficiency on susceptibility to stroke, as a cardiovascular event, and its morbidity and subsequent mortality.

  17. I. Synthesis, characterization, and base catalysis of novel zeolite supported super-basic materials II. Oxidative dehydrogenation of ethane over reduced heteropolyanion catalysts

    Science.gov (United States)

    Galownia, Jonathan M.

    reliable precursor for the formation of zeolite supported super-basic materials. The second part of this thesis describes the oxidative dehydrogenation of ethane over partially reduced heteropolyanions. Niobium and pyridine exchanged salts of phosphomolybdic (NbPMo12Pyr) and phosphovanadomolybdic (NbPMo11VPyr) acids are investigated as catalyst precursors to prepare materials for catalyzing the oxidative dehydrogenation of ethane to ethylene and acetic acid at atmospheric pressure. The effects of feed composition, steam flow, temperature, and precursor composition on catalytic activity and selectivity are presented for both ethane and ethylene oxidation. Production of ethylene and acetic acid from ethane using the catalytic materials exceeds that reported in the literature for Mo-V-Nb-Ox systems under atmospheric or elevated pressure. Production of acetic acid from ethylene is also greater than that observed for Mo-V-Nb-Ox systems. Addition of vanadium reduces catalytic activity and selectivity to both ethylene and acetic acid while niobium is essential for the formation of acetic acid from ethane. Other metals such as antimony, iron, and gallium do not provide the same beneficial effect as niobium. Molybdenum in close proximity to niobium is the active site for ethane activation while niobium is directly involved in the transformation of ethylene to acetic acid. A balance of niobium and protonated pyridine is required to produce an active catalyst. Water is found to aid in desorption of acetic acid, thereby limiting deep oxidation to carbon oxides. A reaction scheme is proposed for the production of acetic acid from ethane over the catalytic materials.

  18. New insights into iron deficiency and iron deficiency anemia.

    Science.gov (United States)

    Camaschella, Clara

    2017-02-13

    Recent advances in iron metabolism have stimulated new interest in iron deficiency (ID) and its anemia (IDA), common conditions worldwide. Absolute ID/IDA, i.e. the decrease of total body iron, is easily diagnosed based on decreased levels of serum ferritin and transferrin saturation. Relative lack of iron in specific organs/tissues, and IDA in the context of inflammatory disorders, are diagnosed based on arbitrary cut offs of ferritin and transferrin saturation and/or marker combination (as the soluble transferrin receptor/ferritin index) in an appropriate clinical context. Most ID patients are candidate to traditional treatment with oral iron salts, while high hepcidin levels block their absorption in inflammatory disorders. New iron preparations and new treatment modalities are available: high-dose intravenous iron compounds are becoming popular and indications to their use are increasing, although long-term side effects remain to be evaluated.

  19. Highly regioselective hydride transfer, oxidative dehydrogenation, and hydrogen-atom abstraction in the thermal gas-phase chemistry of [Zn(OH)](+)/C3H8.

    Science.gov (United States)

    Wu, Xiao-Nan; Zhao, Hai-Tao; Li, Jilai; Schlangen, Maria; Schwarz, Helmut

    2014-12-28

    The thermal reactions of [Zn(OH)](+) with C3H8 have been studied by means of gas-phase experiments and computational investigation. Two types of C-H bond activation are observed in the experiment, and pertinent mechanistic features include inter alia: (i) the metal center of [Zn(OH)](+) serves as active site in the hydride transfer to generate [i-C3H7](+) as major product, (ii) generally, a high regioselectivity is accompanied by remarkable chemoselectivity: for example, the activation of a methyl C-H bond results mainly in the formation of water and [Zn(C3,H7)](+). According to computational work, this ionic product corresponds to [HZn(CH3CH=CH2)](+). Attack of the zinc center at a secondary C-H bond leads preferentially to hydride transfer, thus giving rise to the generation of [i-C3H7](+); (iii) upon oxidative dehydrogenation (ODH), liberation of CH3CH2=CH2 occurs to produce [HZn(H2O)](+). Both, ODH as well as H2O loss proceed through the same intermediate which is characterized by the fact that a methylene hydrogen atom from the substrate is transferred to the zinc and one hydrogen atom from the methyl group to the OH group of [Zn(OH)](+). The combined experimental/computational gas-phase study of C-H bond activation by zinc hydroxide provides mechanistic insight into related zinc-catalyzed large-scale processes and identifies the crucial role that the Lewis-acid character of zinc plays.

  20. Iron complex-catalyzed ammonia-borane dehydrogenation. A potential route toward B-N-containing polymer motifs using earth-abundant metal catalysts.

    Science.gov (United States)

    Baker, R Tom; Gordon, John C; Hamilton, Charles W; Henson, Neil J; Lin, Po-Heng; Maguire, Steven; Murugesu, Muralee; Scott, Brian L; Smythe, Nathan C

    2012-03-28

    Ammonia-borane (NH(3)BH(3), AB) has garnered interest as a hydrogen storage material due to its high weight percent hydrogen content and ease of H(2) release relative to metal hydrides. As a consequence of dehydrogenation, B-N-containing oligomeric/polymeric materials are formed. The ability to control this process and dictate the identity of the generated polymer opens up the possibility of the targeted synthesis of new materials. While precious metals have been used in this regard, the ability to construct such materials using earth-abundant metals such as Fe presents a more economical approach. Four Fe complexes containing amido and phosphine supporting ligands were synthesized, and their reactivity with AB was examined. Three-coordinate Fe(PCy(3))[N(SiMe(3))(2)](2) (1) and four-coordinate Fe(DEPE)[N(SiMe(3))(2)](2) (2) yield a mixture of (NH(2)BH(2))(n) and (NHBH)(n) products with up to 1.7 equiv of H(2) released per AB but cannot be recycled (DEPE = 1,2-bis(diethylphosphino)ethane). In contrast, Fe supported by a bidentate P-N ligand (4) can be used in a second cycle to afford a similar product mixture. Intriguingly, the symmetric analogue of 4 (Fe(N-N)(P-P), 3), only generates (NH(2)BH(2))(n) and does so in minutes at room temperature. This marked difference in reactivity may be the result of the chemistry of Fe(II) vs Fe(0).

  1. Ni-M-O (M=Sn, Ti and W) catalysts prepared from dry mixing method for oxidative dehydrogenation of ethane

    KAUST Repository

    Zhu, Haibo

    2016-03-25

    A new generation of Ni-Sn-O, Ni-Ti-O, and Ni-W-O catalysts has been prepared by a solid state grinding method. In each case the doping metal varied from 2.5% to 20%. These catalysts exhibited higher activity and selectivity for ethane oxidative dehydrogenation (ODH) than conventionally prepared mixed oxides. Detailed characterisation was achieved using XRD, N2 adsorption, H2-TPR, SEM, TEM, and HAADF-STEM in order to study the detailed atomic structure and textural properties of the synthesized catalysts. Two kinds of typical structures are found in these mixed oxides, which are (major) “NixMyO” (M = Sn, Ti or W) solid solution phases (NiO crystalline structure with doping atom incorporated in the lattice) and (minor) secondary phases (SnO2, TiO2 or WO3). The secondary phase exists as a thin layer around small “NixMyO” particles, lowering the aggregation of nanoparticles during the synthesis. DFT calculations on the formation energies of M-doped NiO structures (M = Sn, Ti, W) clearly confirm the thermodynamic feasibility of incorporating these doping metals into NiO struture. The incorporation of doping metals into the NiO lattice decreases the number of holes (h+) localized on lattice oxygen (O2- + h+ ➔ O●-), which is the main reason for the improved catalytic performance (O●- is known to favor complete ethane oxidation to CO2). The high efficiency of ethylene production achieved in these particularly prepared mixed oxide catalysts indicates that the solid grinding method could serve as a general and practical approach for the preparation of doped NiO based catalysts.

  2. Cryptosporidiosis in the acquired immune deficiency syndrome.

    Science.gov (United States)

    Cooper, D A; Wodak, A; Marriot, D J; Harkness, J L; Ralston, M; Hill, A; Penny, R

    1984-10-01

    Cryptosporidiosis was found in a patient with the acquired immune deficiency syndrome. The microbiological and morphological features of this newly recognized opportunistic infection are distinctive and diagnostic.

  3. Vitamin C deficiency in weanling guinea pigs

    DEFF Research Database (Denmark)

    Lykkesfeldt, Jens; Trueba, Gilberto Perez; Poulsen, Henrik E.

    2007-01-01

    Neonates are particularly susceptible to malnutrition due to their limited reserves of micronutrients and their rapid growth. In the present study, we examined the effect of vitamin C deficiency on markers of oxidative stress in plasma, liver and brain of weanling guinea pigs. Vitamin C deficiency...... increased, while protein oxidation decreased (P¼0003). The results show that the selective preservation of brain ascorbate and induction of DNA repair in vitamin C-deficient weanling guinea pigs is not sufficient to prevent oxidative damage. Vitamin C deficiency may therefore be particularly adverse during...

  4. Genetics Home Reference: factor X deficiency

    Science.gov (United States)

    ... deficiency occurs in approximately 1 per million individuals worldwide. Related Information What information about a genetic condition can statistics provide? Why are some genetic conditions more common ...

  5. Iron deficiency anemia in heart failure.

    Science.gov (United States)

    Arora, Natasha P; Ghali, Jalal K

    2013-07-01

    Anemia and iron deficiency are quite prevalent in patients with heart failure (HF) and may overlap. Both anemia and iron deficiency are associated with worse symptoms and adverse clinical outcomes. In the past few years, there has been an enormous interest in the subject of iron deficiency and its management in patients with HF. In this review, the etiology and relevance of iron deficiency, iron metabolism in the setting of HF, studies on iron supplementation in patients with HF and potential cardiovascular effects of subclinical iron overload are discussed.

  6. Catalytic mechanisms of direct pyrrole synthesis via dehydrogenative coupling mediated by PNP-Ir or PNN-Ru pincer complexes: Crucial role of proton-transfer shuttles in the PNP-Ir system

    KAUST Repository

    Qu, Shuanglin

    2014-04-02

    Kempe et al. and Milstein et al. have recently advanced the dehydrogenative coupling methodology to synthesize pyrroles from secondary alcohols (e.g., 3) and β-amino alcohols (e.g., 4), using PNP-Ir (1) and PNN-Ru (2) pincer complexes, respectively. We herein present a DFT study to characterize the catalytic mechanism of these reactions. After precatalyst activation to give active 1A/2A, the transformation proceeds via four stages: 1A/2A-catalyzed alcohol (3) dehydrogenation to give ketone (11), base-facilitated C-N coupling of 11 and 4 to form an imine-alcohol intermediate (18), base-promoted cyclization of 18, and catalyst regeneration via H2 release from 1R/2R. For alcohol dehydrogenations, the bifunctional double hydrogen-transfer pathway is more favorable than that via β-hydride elimination. Generally, proton-transfer (H-transfer) shuttles facilitate various H-transfer processes in both systems. Notwithstanding, H-transfer shuttles play a much more crucial role in the PNP-Ir system than in the PNN-Ru system. Without H-transfer shuttles, the key barriers up to 45.9 kcal/mol in PNP-Ir system are too high to be accessible, while the corresponding barriers (<32.0 kcal/mol) in PNN-Ru system are not unreachable. Another significant difference between the two systems is that the addition of alcohol to 1A giving an alkoxo complex is endergonic by 8.1 kcal/mol, whereas the addition to 2A is exergonic by 8.9 kcal/mol. The thermodynamic difference could be the main reason for PNP-Ir system requiring lower catalyst loading than the PNN-Ru system. We discuss how the differences are resulted in terms of electronic and geometric structures of the catalysts and how to use the features in catalyst development. © 2014 American Chemical Society.

  7. Combined with work reality about styrene device dehydrogenation unit automatic control instrument system%结合工作实际谈谈苯乙烯装置脱氢单元自控仪表系统

    Institute of Scientific and Technical Information of China (English)

    於伟

    2013-01-01

    Is the original work unit and the host of the jiangsu chemical co.,LTD. 150000 tons of styrene plant DCS system are briefly introduced,and the styrene device dehydrogenation unit complex ratio control and V - 305 - T - 301 tower tank of uniform cascade control system in detail,and the F - 301 steam superheater outlet temperature TC - 3008,TC - 3015 - b respectively with fuel gas pressure PICA- 3003/3003,PICA - 3004/3004 b do control scheme of cascade control system,through discussing styrene dehydrogenation unit main control scheme of the automatic control instrument system,discusses the complex control algorithm in the ethylbenzene dehydrogenation stage control system%  就原工作单位江苏利士德化工有限公司15万吨苯乙烯装置 DCS 系统进行简要介绍,对苯乙烯装置上脱氢单元较复杂的 T-301塔比值控制和 V-305罐组成串级均匀控制系统做详细说明,并针对蒸汽过热炉 F-301出口温度 TC-3008,TC-3015分别与燃料气压力 PICA-3003/3003B,PICA-3004/3004B 组成的串级控制系统做控制方案说明,通过论述苯乙烯脱氢单元自控仪表系统的主要控制方案,探讨了复杂控制算法在乙苯脱氢阶段控制系统中的应用。

  8. The impact of maternal iron deficiency and iron deficiency anemia on child’s health

    OpenAIRE

    Abu-Ouf, Noran M.; Jan, Mohammed M.

    2015-01-01

    Iron deficiency anemia is extremely common, particularly in the developing world, reaching a state of global epidemic. Iron deficiency during pregnancy is one of the leading causes of anemia in infants and young children. Many women go through the entire pregnancy without attaining the minimum required intake of iron. This review aims to determine the impact of maternal iron deficiency and iron deficiency anemia on infants and young children. Extensive literature review revealed that iron def...

  9. Cluster in Dehydrogenation of Dodecane to Internal Dodecane in Supercritical Phase%超临界相中正十二烷烃脱氢各物种的聚集行为

    Institute of Scientific and Technical Information of China (English)

    魏伟; 常杰; 孙予罕; 钟炳

    2001-01-01

    The pressure dependence of partial molar volumes was calculatedin detail by R-K equation of state for the dehydrogenation of dodecane to internal dodecane.The results showed that clustering between supercritical medium and internal dodecane and hydrogen was much stronger in supercritical phase than in gas phase,and that,clustering between supercritical medium and the reaction products was more remarkable.This provided a quantitative description of the change in cluster size resulted by an increase in solute-solvent attraction force.

  10. Dehydrogenative Cross-Coupling Reaction between N-Aryl α-Amino Acid Esters and Phenols or Phenol Derivative for Synthesis of α-Aryl α-Amino Acid Esters.

    Science.gov (United States)

    Salman, Muhammad; Zhu, Zhi-Qiang; Huang, Zhi-Zhen

    2016-04-01

    A novel dehydrogenative cross-coupling (DCC) reaction between N-arylglycine esters and phenols or 1,3,5-trimethoxybenzene was developed by copper catalysis using di-tert-butyl peroxide (DTBP) as an oxidant. Under optimized conditions, a range of N-arylglycine esters 1 underwent the DCC reaction smoothly with various phenols 2 or 1,3,5-trimethoxybenzene 4 to give desired α-aryl α -amino acid esters 3 or 5, respectively, with high ortho regioselectivities in a moderate to excellent yield. A possible mechanism involving aromatic electrophilic substitution is proposed.

  11. Genetic causes for iron deficiency

    OpenAIRE

    Saad,Sara Teresinha O.

    2010-01-01

    As causas genéticas de deficiência de ferro, real ou funcional, ocorrem por defeitos em muitas proteínas envolvidas na absorção e metabolismo de ferro. Neste capítulo descreveremos sucintamente causas genéticas de carência de ferro para a síntese de hemoglobina, que cursa então com anemia microcítica e hipocrômica. Ressalto que estas são alterações raras, com poucas descrições na literatura. Em alguns casos, o ferro funcional não está disponível para os eritroblastos sintetizarem hemoglobina,...

  12. [Iron deficiency in the elderly].

    Science.gov (United States)

    Helsen, Tuur; Joosten, Etienne

    2016-06-01

    Anemia is a common diagnosis in the geriatric population, especially in institutionalized and hospitalized elderly. Most common etiologies for anemia in elderly people admitted to a geriatric ward are iron-deficiency anemia and anemia associated with chronic disease. Determination of serum ferritin is the most used assay in the differential diagnosis, despite low sensitivity and moderate specificity. New insights into iron homeostasis lead to new diagnostic assays such as serum hepcidin, serum transferrin receptor and reticulocyte hemoglobin equivalent.Importance of proper diagnosis and treatment for this population is large since there is a correlation between anemia and morbidity - mortality. Anemia is usually defined as hemoglobin less than 12 g/dl for women and less than 13 g/dl for men. There is no consensus for which hemoglobinvalue an investigation into underlying pathology is obligatory. This needs to be evaluated depending on functional condition of the patient.

  13. Photodissociation of neutron deficient nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Sonnabend, K.; Babilon, M.; Hasper, J.; Mueller, S.; Zarza, M.; Zilges, A. [TU Darmstadt, Institut fuer Kernphysik, Darmstadt (Germany)

    2006-03-15

    The knowledge of the cross sections for photodissociation reactions like e.g. ({gamma}, n) of neutron deficient nuclei is of crucial interest for network calculations predicting the abundances of the so-called p nuclei. However, only single cross sections have been measured up to now, i.e., one has to rely nearly fully on theoretical predictions. While the cross sections of stable isotopes are accessible by experiments using real photons, the bulk of the involved reactions starts from unstable nuclei. Coulomb dissociation (CD) experiments in inverse kinematics might be a key to expand the experimental database for p-process network calculations. The approach to test the accuracy of the CD method is explained. (orig.)

  14. [delta-Aminolevulinate dehydratase deficiency].

    Science.gov (United States)

    Fujita, H; Ishida, N; Akagi, R

    1995-06-01

    delta-Aminolevulinate dehydratase (ALAD: E. C. 4.2.1.24), the second enzyme in the heme biosynthetic pathway, condenses two moles of delta-aminolevulinic acid to form porphobilinogen. ALAD deficiency is well known to develop signs and symptoms of typical hepatic porphyria, and classified into three categories as follows: (i) ALAD porphyria, a genetic defect of the enzyme, (ii) tyrosinemia type I, a genetic defect of fumarylacetoacetase in the tyrosine catabolic pathway, producing succinylacetone (a potent inhibitor of ALAD), and (iii) ALAD inhibition by environmental hazards, such as lead, trichloroethylene, and styrene. In the present article, we will describe molecular and biochemical mechanisms to cause the enzyme defect to discuss the significance of ALAD defect on human health.

  15. B12 Deficiency with Children

    Directory of Open Access Journals (Sweden)

    Selahattin Katar

    2007-01-01

    Full Text Available Aim of the study: to rewieved the clinical and laboratory properties of seven cases with megaloblastic anemia. Clinical and laboratory findings of seven cases with megaloblastic anemia are described. İt is determined that all of the patients received little or no animal products by nutritional history. Clinically apatite, malasia, headeche, otism, and parestheia in the lower extremities and foods were present in patients. On physical examination; four patients had glossit, four had hyporeflexia, one had ataxia. Folat level was normal and B12 vitamin level was low in all patients. The MCV (mean corpuscular volume was normal in three patients. Hypersegmentation of neutrophil was observed in all patients, leukopenia in two, and trombocytopenia was observed in one patient.Conclusion: it is suggested B12 vitamin deficiency in the patients that received little or no animal products by nutritional history. However, hypersegmentation of neutrophil in peripheral blood sample is an important finding for diagnosis of megaloblastic anemia.

  16. Vitamin D deficiency in adolescents.

    Science.gov (United States)

    Soliman, Ashraf T; De Sanctis, Vincenzo; Elalaily, Rania; Bedair, Said; Kassem, Islam

    2014-11-01

    The prevalence of severe vitamin D deficiency (VDD) in adolescents is variable but considerably high in many countries, especially in Middle-east and Southeast Asia. Different factors attribute to this deficiency including lack of sunlight exposure due to cultural dress codes and veiling or due to pigmented skin, and less time spent outdoors, because of hot weather, and lower vitamin D intake. A potent adaptation process significantly modifies the clinical presentation and therefore clinical presentations may be subtle and go unnoticed, thus making true prevalence studies difficult. Adolescents with severe VDD may present with vague manifestations including pain in weight-bearing joints, back, thighs and/or calves, difficulty in walking and/or climbing stairs, or running and muscle cramps. Adaptation includes increased parathormone (PTH) and deceased insulin-like growth factor-I (IGF-I) secretion. PTH enhances the tubular reabsorption of Ca and stimulates the kidneys to produce 1, 25-(OH) 2D3 that increases intestinal calcium absorption and dissolves the mineralized collagen matrix in bone, causing osteopenia and osteoporosis to provide enough Ca to prevent hypocalcaemia. Decreased insulin like growth factor-I (IGF-I) delays bone growth to economize calcium consumption. Radiological changes are not uncommon and include osteoporosis/osteopenia affecting long bones as well as vertebrae and ribs, bone cysts, decalcification of the metaphysis of the long bones and pseudo fractures. In severe cases pathological fractures and deformities may occur. Vitamin D treatment of adolescents with VDD differs considerably in different studies and proved to be effective in treating all clinical, biochemical, and radiological manifestations. Different treatment regiments for VDD have been discussed and presented in this mini-review for practical use. Adequate vitamin D replacement after treating VDD, improving calcium intake (milk and dairy products), encouraging adequate exposure

  17. Vitamin A deficiency in quail

    Science.gov (United States)

    Nestler, R.B.; Bailey, W.W.

    1943-01-01

    Two experiments were conducted to determine the symptoms of avitaminosis A in growing and adolescent bobwhites. Chicks from parents that have received a diet rich in vitamin A may have enough stored to carry them a week or ten days on a growing diet deficient in vitamin A before symptoms of deficiency occur. The first sign is ruffled feathering, with the wing primaries standing out from the body and drooping. Ophthalmia in one or both eyes occurs and may close the eyes completely, but this condition is not severe in all cases and may not even be noticeable. Birds show poor growth, loss of appetite, and weakness before death. Under the conditions of the experiments discussed herein, death may occur in the fourth or fifth week, and mortality is high......Postmortem examination may reveal visceral gout with thick deposits of urates on the kidneys, in the ureters, on the heart, in the proventriculus, and occasionally covering all the viscera. There may also be hemorrhage of the heart and other organs....Adolescent quail reared on a diet rich in vitamin A may be able to live through the winter on a maintenance diet low in this vitamin without showing symptoms of avitaminosis, but some individuals whose storage of vitamin A in the liver is not as great as that of others may succumb to visceral gout.....A growing mash for quail which contains sufficient vitamin A when fresh may, after a period of storage, lose enough of the vitamin to cause the characteristic symptoms of avitaminosis A to appear.

  18. Growth hormone deficiency and hyperthermia during exercise

    DEFF Research Database (Denmark)

    Juul, A; Hjortskov, N; Jepsen, Leif

    1995-01-01

    -deficiency may be at risk for developing hyperthermia. To pursue this, we performed a controlled study on sweating and body temperature regulation during exercise in the heat in 16 GH-treated GH-deficient patients with normalized insulin-like growth factor-I and insulin-like growth factor/binding protein-3 serum...

  19. Growth Hormone Deficiency, Brain Development, and Intelligence

    Science.gov (United States)

    Meyer-Bahlburg, Heino F. L.; And Others

    1978-01-01

    Available from: American Medical Association, 535 N. Dearborn Street, Chicago, Illinois 60610. In order to determine what effect, if any, growth hormone (GH) has on human brain development, 29 patients (mean age 11.7 years) with GH deficiency were selected according to the following criteria: no evidence of reversible GH deficiency, onset of…

  20. How common is vitamin B12 deficiency?

    Science.gov (United States)

    In considering the vitamin B-12 fortification of flour, it is important to know who is at risk of vitamin B-12 deficiency and whether those individuals would benefit from flour fortification.This article reviews current knowledge of the prevalence and causes of vitamin B-12 deficiency and considers ...

  1. Duodenal Amyloidosis Masquerading as Iron Deficiency Anemia

    Science.gov (United States)

    Hurairah, Abu

    2016-01-01

    The present study is a unique illustration of duodenal amyloidosis initially manifesting with iron deficiency anemia. It underscores the importance of clinical suspicion of amyloidosis while performing upper gastrointestinal endoscopy with a biopsy to establish the definite diagnosis in patients with unexplained iron deficiency anemia. PMID:27625911

  2. Molecular diagnosis of coenzyme Q10 deficiency.

    Science.gov (United States)

    Yubero, Delia; Montero, Raquel; Armstrong, Judith; Espinós, Carmen; Palau, Francesc; Santos-Ocaña, Carlos; Salviati, Leonardo; Navas, Placido; Artuch, Rafael

    2015-01-01

    Coenzyme Q10 (CoQ) deficiency syndromes comprise a growing number of neurological and extraneurological disorders. Primary-genetic but also secondary CoQ deficiencies have been reported. The biochemical determination of CoQ is a good tool for the rapid identification of CoQ deficiencies but does not allow the selection of candidate genes for molecular diagnosis. Moreover, the metabolic pathway for CoQ synthesis is an intricate and not well-understood process, where a large number of genes are implicated. Thus, only next-generation sequencing techniques (either genetic panels of whole-exome and -genome sequencing) are at present appropriate for a rapid and realistic molecular diagnosis of these syndromes. The potential treatability of CoQ deficiency strongly supports the necessity of a rapid molecular characterization of patients, since primary CoQ deficiencies may respond well to CoQ treatment.

  3. Prevalence of Color Vision Deficiency in Qazvin

    Directory of Open Access Journals (Sweden)

    Mohammad khalaj

    2014-01-01

    Full Text Available Background: Color vision deficiency (CVD is an X chromosome-linked recessive autosomal dominant. Determine the prevalence of color blindness in Qazvin population. Materials and Methods: In a cross sectional study color vision deficiency examined in 1853 individuals with age 10-25 years old who participated in private clinics and eye clinic of Bu-Ali hospital in Qazvin in 2010. The screening of color vision deficiency was performed using Ishihara test. Data were analyzed by SPSS-16 with χP2P test with p<0.05. Results: Mean age of participant was 17.86±4.48 years. 59.5% of them were female. 3.49% of the total population had color vision deficiency that 0.93% and 2.56% were female and male respectively. Conclusion: color vision deficiency must be noticed by decision makers in health field for screen planning.

  4. [Trial of indirect screening of tetrahydrobiopterin deficiency].

    Science.gov (United States)

    Ferraris, S; Guardamagna, O; Bracco, G; Ponzone, A

    1987-01-01

    The possibility of an early diagnosis of tetrahydrobiopterin deficiency among hyperphenylalaninemic infants, when specific screening tests cannot be performed, was evaluated. Three tetrahydrobiopterin deficient patients, two with dihydropteridine reductase deficiency and one with dihydrobiopterin synthetase deficiency were examined together with their parents and compared with twelve phenylketonuric patients, their parents and sixteen normal subjects. The parameters considered in the hyperphenylalaninemic patients (degree of neonatal hyperphenylalaninemia, phenylalanine lowering speed in response to a restricted diet, dietary tolerance to phenylalanine, oral phenylalanine load) were found to be insufficiently or lately indicative. By contrast, heterozygosity tests (molar ratio (Phe)2/Tyr and sigma discriminant function) performed on the parents allowed a suspicion of tetrahydrobiopterin deficiency, the definite diagnosis being of course based upon specific investigations.

  5. [Vitamin B12 deficiency in the elderly].

    Science.gov (United States)

    Leischker, A H; Kolb, G F

    2015-01-01

    The prevalence of vitamin B12 deficiency increases with age. Patients with dementia and spouses of patients with dementia are at special risk for the development of vitamin B12 deficiency. In a normal diet this vitamin is present only in animal source foods; therefore, vegans frequently develop vitamin B12 deficiency if not using supplements or foods fortified with cobalamin. Apart from dementia, most of these manifestations are completely reversible under correct therapy; therefore it is crucial to identify and to treat even atypical presentations of vitamin B12 deficiency as early as possible. This article deals with the physiology and pathophysiology of vitamin B12 metabolism. A practice-oriented algorithm which also considers health economic aspects for a rational laboratory diagnosis of vitamin B12 deficiency is presented. In cases with severe neurological symptoms, therapy should be parenteral, especially initially. For parenteral treatment, hydroxocobalamin is the drug of choice.

  6. Vitamin D deficiency in adolescents

    Directory of Open Access Journals (Sweden)

    Ashraf T Soliman

    2014-01-01

    Full Text Available The prevalence of severe vitamin D deficiency (VDD in adolescents is variable but considerably high in many countries, especially in Middle-east and Southeast Asia. Different factors attribute to this deficiency including lack of sunlight exposure due to cultural dress codes and veiling or due to pigmented skin, and less time spent outdoors, because of hot weather, and lower vitamin D intake. A potent adaptation process significantly modifies the clinical presentation and therefore clinical presentations may be subtle and go unnoticed, thus making true prevalence studies difficult. Adolescents with severe VDD may present with vague manifestations including pain in weight-bearing joints, back, thighs and/or calves, difficulty in walking and/or climbing stairs, or running and muscle cramps. Adaptation includes increased parathormone (PTH and deceased insulin-like growth factor-I (IGF-I secretion. PTH enhances the tubular reabsorption of Ca and stimulates the kidneys to produce 1, 25-(OH 2D3 that increases intestinal calcium absorption and dissolves the mineralized collagen matrix in bone, causing osteopenia and osteoporosis to provide enough Ca to prevent hypocalcaemia. Decreased insulin like growth factor-I (IGF-I delays bone growth to economize calcium consumption. Radiological changes are not uncommon and include osteoporosis/osteopenia affecting long bones as well as vertebrae and ribs, bone cysts, decalcification of the metaphysis of the long bones and pseudo fractures. In severe cases pathological fractures and deformities may occur. Vitamin D treatment of adolescents with VDD differs considerably in different studies and proved to be effective in treating all clinical, biochemical, and radiological manifestations. Different treatment regiments for VDD have been discussed and presented in this mini-review for practical use. Adequate vitamin D replacement after treating VDD, improving calcium intake (milk and dairy products, encouraging

  7. Infections Revealing Complement Deficiency in Adults

    Science.gov (United States)

    Audemard-Verger, A.; Descloux, E.; Ponard, D.; Deroux, A.; Fantin, B.; Fieschi, C.; John, M.; Bouldouyre, A.; Karkowsi, L.; Moulis, G.; Auvinet, H.; Valla, F.; Lechiche, C.; Davido, B.; Martinot, M.; Biron, C.; Lucht, F.; Asseray, N.; Froissart, A.; Buzelé, R.; Perlat, A.; Boutboul, D.; Fremeaux-Bacchi, V.; Isnard, S.; Bienvenu, B.

    2016-01-01

    Abstract Complement system is a part of innate immunity, its main function is to protect human from bacterial infection. As genetic disorders, complement deficiencies are often diagnosed in pediatric population. However, complement deficiencies can also be revealed in adults but have been poorly investigated. Herein, we describe a case series of infections revealing complement deficiency in adults to study clinical spectrum and management of complement deficiencies. A nationwide retrospective study was conducted in French university and general hospitals in departments of internal medicine, infectious diseases enrolling patients older than 15 years old who had presented at least one infection leading to a complement deficiency diagnosis. Forty-one patients included between 2002 and 2015 in 19 different departments were enrolled in this study. The male-to-female ratio was 1.3 and the mean age at diagnosis was 28 ± 14 (15–67) years. The main clinical feature was Neisseria meningitidis meningitis 75% (n = 31/41) often involving rare serotype: Y (n = 9) and W 135 (n = 7). The main complement deficiency observed was the common final pathway deficiency 83% (n = 34/41). Half of the cohort displayed severe sepsis or septic shock at diagnosis (n = 22/41) but no patient died. No patient had family history of complement deficiency. The mean follow-up was 1.15 ± 1.95 (0.1–10) years. Half of the patients had already suffered from at least one infection before diagnosis of complement deficiency: meningitis (n = 13), pneumonia (n = 4), fulminans purpura (n = 1), or recurrent otitis (n = 1). Near one-third (n = 10/39) had received prophylactic antibiotics (cotrimoxazole or penicillin) after diagnosis of complement deficiency. The vaccination coverage rate, at the end of the follow-up, for N meningitidis, Streptococcus pneumonia, and Haemophilius influenzae were, respectively, 90% (n = 33/37), 47% (n = 17/36), and 35

  8. Surface Acidity/Basicity and Catalytic Reactivity of CeO2/γ-Al2O3 Catalysts for the Oxidative Dehydrogenation of Ethane with Carbon Dioxide to Ethylene

    Institute of Scientific and Technical Information of China (English)

    Xin Ge; Shenghua Hu; Qing Sun; Jianyi Shen

    2003-01-01

    Dehydrogenation of ethane to ethylene in CO2 was investigated over CeO2/γ-Al2O3 catalysts at 700 ℃ in a conventional flow reactor operating at atmospheric pressure. XRD, BET and microcalorimetric adsorption techniques were used to characterize the structure and surface acidity/basicity of the CeO2/γ-Al2O3 catalysts. The results show that the surface acidity decreased while the surface basicity increased after the addition of CeO2 to γ-Al2O3. Accordingly, the activity of the hydrogenation reaction of CO2 increased, which might be responsible for the enhanced conversion in the dehydrogenation of ethane to ethylene. The highest ethane conversion obtained was about 15% for the 25%CeO2/γ-Al2O3. The selectivity to ethylene was high for all the CeO2, γ-Al2O3 and CeO2/γ-Al2O3 catalysts.

  9. Genetics Home Reference: ataxia with vitamin E deficiency

    Science.gov (United States)

    ... Home Health Conditions ataxia with vitamin E deficiency ataxia with vitamin E deficiency Enable Javascript to view ... boxes. Download PDF Open All Close All Description Ataxia with vitamin E deficiency is a disorder that ...

  10. Genetic, molecular and functional analyses of complement factor I deficiency

    DEFF Research Database (Denmark)

    Nilsson, S.C.; Trouw, L.A.; Renault, N.;

    2009-01-01

    Complete deficiency of complement inhibitor factor I (FI) results in secondary complement deficiency due to uncontrolled spontaneous alternative pathway activation leading to susceptibility to infections. Current genetic examination of two patients with near complete FI deficiency and three...

  11. Genetics Home Reference: iron-refractory iron deficiency anemia

    Science.gov (United States)

    ... refractory iron deficiency anemia iron-refractory iron deficiency anemia Enable Javascript to view the expand/collapse boxes. ... All Close All Description Iron-refractory iron deficiency anemia is one of many types of anemia , which ...

  12. Tungsten(VI) hexahydride complexes supported by chelating triphosphine ligands: Protonation to give [eta][sup 2]-dihydrogen complexes and catalytic dehydrogenation of cyclooctane to cyclooctene

    Energy Technology Data Exchange (ETDEWEB)

    Michos, D.; Xiaoliang Luo; Faller, J.W.; Crabtree, R.H. (Yale Univ., New Haven, CT (United States))

    1993-04-14

    Reactions of WCl[sub 4](PPh[sub 3])[sub 2][center dot]CH[sub 2]Cl[sub 2] with the chelating triphosphine (triphos) ligands PPh(CH[sub 2]CH[sub 2]PPh[sub 2])[sub 2] (PP[sub 2]), PPh(C[sub 6]H[sub 4]-o-PPh[sub 2])[sub 2] (TP), and MeC(CH[sub 2]PPh[sub 2])[sub 3] (P[sub 3]) in refluxing benzene or toluene give WCl[sub 4](triphos) (triphos = PP[sub 2] (1), TP (2), (3)). Treat of 1-3 with LiAlH[sub 4] in Et[sub 2]O at room temperature followed by hydrolysis in THF at 0[degrees]C affords WH[sub 6](triphos) (triphos = PP[sub 2] (4), TP (5), P[sub 3] (6)), which are the first tungsten polyhydride complexes supported by a chelating triphosphine ligand. Variable-temperature [sup 1]H NMR spectra and T[sub 1] data of 4-6 are consistent with the formulation of them as classical hexahydride complexes containing no [eta][sup 2]-H[sub 2] ligands. Reaction of 4 with Ph[sub 3]SiH in refluxing THF gives the rare silyl polyhydride complex WH[sub 5](SiPh[sub 3])(PP[sub 2]) (7). Protonation of 4-6 with HBF[sub 4][center dot]OEt[sub 2] in CD[sub 2]Cl[sub 2] at 193 K affords the cationic nonclassical [eta][sup 2]-H[sub 2] complexes [WH[sub 7[minus]2x]([eta][sup 2]-H[sub 2])[sub x](triphos)][sup +] (triphos = PP[sub 2] (8), TP (9), P[sub 3] (10); x = 1-3). Deprotonation of 8-10 with NEt[sub 3] regenerates the parent hexahydrides 4-6 quantitatively. The variable-temperature [sup 1]H NMR T[sub 1] data for the hydride resonances of 8-10 are consistent with the nonclassical [eta][sup 2]-H[sub 2] coordination. In the presence of tert-butylethylene as a hydrogen acceptor, complexes 4 and ReH[sub 5](PP[sub 2]) (11) are active catalysts for the thermal dehydrogenation of cyclooctane to cyclooctene, whereas their analogues containing monodentate phosphine ligands are inactive under similar conditions. 42 refs., 1 fig., 1 tab.

  13. Deficient Approaches to Human Neuroimaging

    Directory of Open Access Journals (Sweden)

    Johannes eStelzer

    2014-07-01

    Full Text Available Functional magnetic resonance imaging (fMRI is the workhorse of imaging-based human cognitive neuroscience. The use of fMRI is ever-increasing; within the last 4 years more fMRI studies have been published than in the previous 17 years. This large body of research has mainly focused on the functional localization of condition- or stimulus-dependent changes in the blood-oxygenation-level dependent (BOLD signal.In recent years, however, many aspects of the commonly practiced analysis frameworks and methodologies have been critically reassessed. Here we summarize these critiques, providing an overview of the major conceptual and practical deficiencies in widely used brain-mapping approaches, and exemplify some of these issues by the use of imaging data and simulations. In particular, we discuss the inherent pitfalls and shortcomings of methodologies for statistical parametric mapping. Our critique emphasizes recent reports of excessively high numbers of both false positive and false negative findings in fMRI brain mapping. We outline our view regarding the broader scientific implications of these methodological considerations and briefly discuss possible solutions.

  14. Testosterone deficiency and cardiovascular mortality

    Institute of Scientific and Technical Information of China (English)

    Abraham Morgentaler

    2015-01-01

    New concerns have been raised regarding cardiovascular (CV) risks with testosterone (T) therapy (TTh). These concerns are based primarily on two widely reported retrospective studies. However, methodological flaws and data errors invalidate both studies as credible evidence of risk. One showed reduced adverse events by half in T‑treated men but reversed this result using an unproven statistical approach. The authors subsequently acknowledged serious data errors including nearly 10% contamination of the dataset by women. The second study mistakenly used the rate of T prescriptions written by healthcare providers to men with recent myocardial infarction (MI) as a proxy for the naturally occurring rate of MI. Numerous studies suggest T is beneficial, including decreased mortality in association with TTh, reduced MI rate with TTh in men with the greatest MI risk prognosis, and reduced CV and overall mortality with higher serum levels of endogenous T. Randomized controlled trials have demonstrated benefits of TTh in men with coronary artery disease and congestive heart failure. Improvement in CV risk factors such as fat mass and glycemic control have been repeatedly demonstrated in T‑deficient men treated with T. The current evidence does not support the belief that TTh is associated with increased CV risk or CV mortality. On the contrary, a wealth of evidence accumulated over several decades suggests that low serum T levels are associated with increased risk and that higher endogenous T, as well as TTh itself, appear to be beneficial for CV mortality and risk.

  15. Perinatal iron deficiency and neurocognitive development

    Directory of Open Access Journals (Sweden)

    Emily Clare Radlowski

    2013-09-01

    Full Text Available Iron deficiency is the most common form of nutrient deficiency worldwide. It is highly prevalent due to the limited availability of high quality food in developing countries, and poor dietary habits in industrialized countries. According to the World Health Organization, it affects nearly 2 billion people and up to 50% of women who are pregnant. Maternal anemia during pregnancy is especially burdensome to healthy neurodevelopment in the fetus because iron is needed for proper neurogenesis, development, and myelination. Maternal anemia also increases the risk of low birth weight, either due to premature birth or fetal growth restriction, which is associated with delayed neurocognitive development and even psychiatric illness. As rapid neurodevelopment continues after birth infants that received sufficient iron in utero, but that receive a low iron diet after 6 months of age, also show deficits in neurocognitive development, including impairments in learning and memory. Unfortunately, the neurocognitive complications of iron deficiency during critical pre- and postnatal periods of brain development are difficult to remedy, persisting into adulthood. Thus, preventing iron deficiency in the pre- and postnatal periods is critical as is devising new means to recapture cognitive function in individuals who experienced early iron deficiency. This review will discuss the prevalence of pre- and postnatal iron deficiency, the mechanism, and effects of iron deficiency on brain and cognitive development.

  16. Treatment of zinc deficiency without zinc fortification

    Institute of Scientific and Technical Information of China (English)

    Donald OBERLEAS; Barbara F. HARLAND

    2008-01-01

    Zinc (Zn) deficiency in animals became of interest until the 1950s. In this paper, progresses in researches on physi-ology of Zn deficiency in animals, phytate effect on bioavailability of Zn, and role of phytase in healing Zn deficiency of animals were reviewed. Several studies demonstrated that Zn is recycled via the pancreas; the problem of Zn deficiency was controlled by Zn homeostasis. The endogenous secretion of Zn is considered as an important factor influencing Zn deficiency, and the critical molar ratio is 10. Phytate (inositol hexaphosphate) constituted up to 90% of the organically bound phosphorus in seeds. Great improvement has been made in recent years on isolating and measuring phytate, and its structure is clear. Phytate is considered to reduce Zn bioavailability in animal. Phytase is the enzyme that hydrolyzes phytate and is present in yeast, rye bran, wheat bran, barley, triticale, and many bacteria and fungi. Zinc nutrition and bioavailability can be enhanced by addition of phytase to animal feeds. Therefore, using phytase as supplements, the most prevalent Zn deficiency in animals may be effectively corrected without the mining and smelting of several tons of zinc daily needed to correct this deficiency by fortification worldwide.

  17. Reticulocyte maturity indices in iron deficiency anemia

    Directory of Open Access Journals (Sweden)

    Muriel Wollmann

    2014-01-01

    Full Text Available Objective: The aim of this study was to analyze the reticulocyte maturity indices (low, medium, and high fluorescence ratios in iron deficient 1- to 6-year-old children, and identify the prevalence of iron deficiency anemia in this population. Methods: The present study included 39 subjects, divided into two groups: control subjects (n = 33, and subjects with iron deficiency anemia (n = 6. The results were analyzed by Student's t-test for comparison of means. Differences were considered significant when two-tailed p-value < 0.05. Results: Subjects with iron deficiency anemia presented increases in the proportion of mean (10.3 ± 4.7% vs. 6.0 ± 3.4%; p-value = 0.003, and high fluorescence reticulocytes (2.3 ± 0.87% vs. 0.9 ± 0.9%; p-value = 0.03 compared to the control group. The prevalence of anemia in this population was 15% (n = 6. Conclusion: The indices related to immaturity of reticulocytes are higher in the presence of iron deficiency, thus demonstrating a deficiency in the raw material to form hemoglobin and are, therefore, possible early markers of iron deficiency and anemia. We emphasize the need to standardize these indices for use in clinical practice and lab test results.

  18. Antibiotic prophylaxis in primary immune deficiency disorders.

    Science.gov (United States)

    Kuruvilla, Merin; de la Morena, Maria Teresa

    2013-01-01

    Long-term prophylactic antibiotics are being widely implemented as primary or adjunctive therapy in primary immune deficiencies. This practice has transformed clinical outcomes in the setting of chronic granulomatous disease, complement deficiencies, Mendelian susceptibility to mycobacterial disease, Wiskott-Aldrich syndrome, hyper-IgE syndrome, Toll signaling defects, and prevented Pneumocystis in patients with T-cell deficiencies. Yet, controlled trials are few in the context of primary antibody deficiency syndromes, and most of this practice has been extrapolated from data in patients who are immune competent and with recurrent acute otitis media, chronic rhinosinusitis, cystic fibrosis, and bronchiectasis. The paucity of guidelines on the subject is reflected in recent surveys among practicing immunologists that highlight differences of habit regarding this treatment. Such discrepancies reinforce the lack of standard protocols on the subject. This review will provide evidence for the use of antibiotic prophylaxis in various primary immune deficiency populations, especially highlighting the role antibiotic prophylaxis in primary antibody deficiency syndromes. We also discussed the relationship of long-term antibiotic use and the prevalence of resistant pathogens. Overall, examination of available data on the use of prophylactic antibiotics in antibody deficiency syndromes merit future investigation in well-designed multicenter prospective trials because this population has few other management options.

  19. Responses of Legumes to Phosphorus Deficiency

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Phosphorus deficiency is a universal problem in most world soils. Furthermore, of all nutrients, shortage of phosphorus has the biggest impact on legumes, therefore, lots of studies were carried out for identifying responses of legumes to shortage of phosphorus. They concluded that to maintain improved growth under phosphorus deficiency conditions plants develop two major mechanisms: (i) Phosphorus acquisition (root morphology, root exudation and phosphorus uptake mechanisms), (ii) Phosphorus utilization (internal mechanisms associated with better use of absorbed phosphorus at cellular level). The aim of this brief review is to elucidate root morphological changes and rhizophere acidification to phosphorus deficiency.

  20. Molecular genetics of human lactase deficiencies.

    Science.gov (United States)

    Järvelä, Irma; Torniainen, Suvi; Kolho, Kaija-Leena

    2009-01-01

    Lactase non-persistence (adult-type hypolactasia) is present in more than half of the human population and is caused by the down-regulation of lactase enzyme activity during childhood. Congenital lactase deficiency (CLD) is a rare severe gastrointestinal disorder of new-borns enriched in the Finnish population. Both lactase deficiencies are autosomal recessive traits and characterized by diminished expression of lactase activity in the intestine. Genetic variants underlying both forms have been identified. Here we review the current understanding of the molecular defects of human lactase deficiencies and their phenotype-genotype correlation, the implications on clinical practice, and the understanding of their function and role in human evolution.

  1. Severe Vitamin D Deficiency Causing Kyphoscoliosis.

    Science.gov (United States)

    Singhai, Abhishek; Banzal, Subodh

    2013-01-01

    Vitamin D deficiency is common among Indian population. Women are especially at risk for severe vitamin D deficiency. The risk is higher for those who are multiparous and postmenopausal. Poor exposure to sunlight, higher latitude, winter season, inadequate diet, older age, obesity and malabsorption are also important risk factors. Symptoms of hypovitaminosis D, including diffuse or migratory pain affecting several sites (especially the shoulder, pelvis, ribcage and lower back) have also been misdiagnosed as musculoskeletal disorders, including fibromyalgia, polymyalgia rheumatica and ankylosing spondylitis. Here, we report two cases presented with kyphoscoliosis, diagnosed to have severe vitamin D deficiency.

  2. Nutrition and hair: deficiencies and supplements.

    Science.gov (United States)

    Finner, Andreas M

    2013-01-01

    Hair follicle cells have a high turnover. A caloric deprivation or deficiency of several components, such as proteins, minerals, essential fatty acids, and vitamins, caused by inborn errors or reduced uptake, can lead to structural abnormalities, pigmentation changes, or hair loss, although exact data are often lacking. The diagnosis is established through a careful history, clinical examination of hair loss activity, and hair quality and confirmed through targeted laboratory tests. Examples of genetic hair disorders caused by reduced nutritional components are zinc deficiency in acrodermatitis enteropathica and copper deficiency in Menkes kinky hair syndrome.

  3. An uncommon presentation of hexosaminidase deficiency

    Directory of Open Access Journals (Sweden)

    Iype Mary

    2006-01-01

    Full Text Available Focal muscular atrophy (FMA can occur due to several causes. We report three cases of FMA associated with deficiency of hexosaminidase A. The serum level of hexosaminidase A was assayed in seven patients with FMA without any definite aetiology identified over a period of two years. Three cases of FMA showed deficiency of hexosaminidase A. All these patients had clinical features of isolated lower motor neurone involvement in one limb without any evidence of involvement of the rest of the neuraxis. Detailed laboratory tests were negative. Electromyography confirmed neurogenic involvement without any evidence of radiculopathy or neuropathy. Hexosaminidase deficiency as a possible association for FMA is highlighted.

  4. Hypopituitarism: growth hormone and corticotropin deficiency.

    Science.gov (United States)

    Capatina, Cristina; Wass, John A H

    2015-03-01

    This article presents an overview of adult growth hormone deficiency (AGHD) and corticotropin deficiency (central adrenal failure, CAI). Both conditions can result from various ailments affecting the hypothalamus or pituitary gland (most frequently a tumor in the area or its treatment). Clinical manifestations are subtle in AGHD but potentially life-threatening in CAI. The diagnosis needs dynamic testing in most cases. Treatment of AGHD is recommended in patients with documented severe deficiency, and treatment of CAI is mandatory in all cases. Despite significant progress in replacement hormonal therapy, more physiologic treatments and more reliable indicators of treatment adequacy are still needed.

  5. Growth hormone deficiency and hyperthermia during exercise

    DEFF Research Database (Denmark)

    Juul, A; Hjortskov, N; Jepsen, Leif

    1995-01-01

    Sweat secretion is often disturbed in patients with GH secretory disorders. Hyperhidrosis is a classic feature of acromegaly, and it has recently been shown that GH-deficient patients exhibit decreased sweating capacity after pilocarpine stimulation of the skin. Thus, patients with GH-deficiency ......Sweat secretion is often disturbed in patients with GH secretory disorders. Hyperhidrosis is a classic feature of acromegaly, and it has recently been shown that GH-deficient patients exhibit decreased sweating capacity after pilocarpine stimulation of the skin. Thus, patients with GH...

  6. 21-Hydroxylase deficiency in Brazil

    Directory of Open Access Journals (Sweden)

    T.A.S.S. Bachega

    2000-10-01

    Full Text Available We determined the frequency of large rearrangements and point mutations in 130 Brazilian patients with 21-hydroxylase deficiency and correlated genotype with phenotype. The frequency of CYP21 deletions was lower (4.4% than in most of the previous series described, whereas the frequency of large gene conversions was similar to the frequency reported in the literature (6.6%. The most frequent point mutations were I2 splice (41.8% in salt wasting - SW, I172N (32.6% in simple virilizing - SV and V281L (40.2% in the late onset form - LO. The frequency of the nine most common point mutations was similar to that reported for other countries. The 93 fully genotyped patients were classified into 3 mutation groups based on the degree of enzymatic activity (A@ 2%, C>20%. In group A, 62% of cases presented the SW form; in group B, 96% the SV form, and in group C, 88% the LO form. We diagnosed 80% of the affected alleles after screening for large rearrangements and 15 point mutations. To diagnose these remaining alleles we sequenced the CYP21 gene of one patient with the SV form and identified a heterozygous G->A transition in codon 424. This mutation leads to a substitution of glycine by serine in a conserved region and was also found in a compound heterozygous state in 4 other patients. The mutation G424S presented a linkage disequilibrium with CYP21P and C4A gene deletions and HLA DR17, suggesting a probable founder effect. Search for the G424S mutation in other populations will reveal if it is restricted to the Brazilian patients or if it has a wider ethnic distribution.

  7. Vitamin K deficiency bleeding of the newborn

    Science.gov (United States)

    Vitamin K deficiency bleeding of the newborn (VKDB) is a bleeding disorder in babies. It most often ... A lack of vitamin K may cause severe bleeding in newborn babies. Vitamin K plays an important role in blood clotting. Babies often ...

  8. Genetics Home Reference: dihydropyrimidine dehydrogenase deficiency

    Science.gov (United States)

    ... of the skin on the palms and soles (hand-foot syndrome); shortness of breath; and hair loss may also ... dehydrogenase deficiency , with its early-onset neurological symptoms, is a rare disorder. Its prevalence is ...

  9. FastStats: Anemia or Iron Deficiency

    Science.gov (United States)

    ... this? Submit What's this? Submit Button NCHS Home Anemia or Iron Deficiency Recommend on Facebook Tweet Share ... visits Number of visits to emergency departments with anemia as the primary hospital discharge diagnosis: 146,000 ...

  10. Genetics Home Reference: primary carnitine deficiency

    Science.gov (United States)

    ... Majdalani M. Primary carnitine deficiency: novel mutations and insights into the cardiac phenotype. Clin Genet. 2014 Feb; ... healthcare professional . About Genetics Home Reference Site Map Customer Support Selection Criteria for Links USA.gov Copyright ...

  11. Iron-Deficiency Anemia and Stroke

    OpenAIRE

    J Gordon Millichap

    2007-01-01

    The prevalence of iron-deficiency anemia (IDA) in young children at the time of stroke and in age-matched healthy controls was compared in a case-control study conducted at the Hospital for Sick Children, Toronto, Canada.

  12. Oxygen deficiency in the North Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A

    in contact with oxygen-depleted waters. Impacts of the oxygen deficiency on regional biogeochemistry, especially anaerobic nitrogen transformaions, are described. A comparison of the perrenial, mesopelagic OMZ in the open Northwestern Indian Ocean is made...

  13. Genetics Home Reference: guanidinoacetate methyltransferase deficiency

    Science.gov (United States)

    ... Facebook Share on Twitter Your Guide to Understanding Genetic Conditions Search MENU Toggle navigation Home Page Search ... Conditions Genes Chromosomes & mtDNA Resources Help Me Understand Genetics Home Health Conditions guanidinoacetate methyltransferase deficiency guanidinoacetate methyltransferase ...

  14. Genetics Home Reference: GM3 synthase deficiency

    Science.gov (United States)

    ... Facebook Share on Twitter Your Guide to Understanding Genetic Conditions Search MENU Toggle navigation Home Page Search ... Conditions Genes Chromosomes & mtDNA Resources Help Me Understand Genetics Home Health Conditions GM3 synthase deficiency GM3 synthase ...

  15. Isoprenoid biosynthesis and mevalonate kinase deficiency

    NARCIS (Netherlands)

    Henneman, L.

    2011-01-01

    Mevalonaat Kinase Deficiëntie (MKD) is een aangeboren ziekte geassocieerd met heftige koortsaanvallen die drie tot vier dagen aanhouden en gepaard gaan met koude rillingen, gewrichtsklachten, huiduitslag, hoofdpijn, duizeligheid, buikpijn, braken en diarree. De koortsaanvallen treden gemiddeld eens

  16. Genetics Home Reference: phosphoglycerate mutase deficiency

    Science.gov (United States)

    ... production in these cells. This defect underlies the muscle cramping and myoglobinuria that occur after strenuous exercise in ... phosphoglycerate mutase deficiency , including episodes of exercise-induced muscle cramping and myoglobinuria. Related Information What does it mean ...

  17. Iron Deficiency, Zinc, Magnesium, Vitamin Deficiencies in Crohn's Disease: Substitute or Not?

    Science.gov (United States)

    Kruis, Wolfgang; Phuong Nguyen, G

    2016-01-01

    Inflammatory bowel disease (IBD) is characterized by inflammatory reactions, complications, extraintestinal manifestations and a loss of intestinal functions, for example, failures of absorption and secretion. According to intestinal dysfunction, a wide array of pathogenetic pathways is existing leading to iron deficiency and numerous vitamins as well as trace element deficiencies. Complications, symptoms and signs of those deficiencies are common in IBD with varying degrees of clinical significance. This review focuses on selected micronutrients including iron, zinc, magnesium and some vitamins. Epidemiology with respect to IBD, pathophysiology, diagnosis and clinical aspects are addressed. Finally, some suggestions for treatment of deficient situations are discussed. In conclusion, some micronutrients have significant impact on complications and quality of life in IBD. Deficiencies may even influence the course of the disease. Those deficiencies should be thoroughly supplemented.

  18. Cushing, acromegaly, GH deficiency and tendons

    OpenAIRE

    2014-01-01

    Cushing’s syndrome, induced by an endogenous or exogenous cortisol excess, and acromegaly, the clinical syndrome caused by growth hormone (GH) excess in adulthood, as well as the disease induced by GH deficiency (GHD), represent perfect models for the evaluation of the effects induced by chronic exposure in vivo, respectively, to cortisol and GH/IGF-1 excess or deficiency on the complex structure of the tendons as well as on the related post-traumatic repair mechanism. Although the literature...

  19. Deficiently Extremal Cohen-Macaulay Algebras

    Indian Academy of Sciences (India)

    Chanchal Kumar; Pavinder Singh

    2010-04-01

    The aim of this paper is to study homological properties of deficiently extremal Cohen–Macaulay algebras. Eagon–Reiner showed that the Stanley–Reisner ring of a simplicial complex has a linear resolution if and only if the Alexander dual of the simplicial complex is Cohen–Macaulay. An extension of a special case of Eagon–Reiner theorem is obtained for deficiently extremal Cohen–Macaulay Stanley–Reisner rings.

  20. Anemia and iron deficiency in heart failure.

    Science.gov (United States)

    Gil, Victor M; Ferreira, Jorge S

    2014-01-01

    Heart failure is a common problem and a major cause of mortality, morbidity and impaired quality of life. Anemia is a frequent comorbidity in heart failure and further worsens prognosis and disability. Regardless of anemia status, iron deficiency is a common and usually unidentified problem in patients with heart failure. This article reviews the mechanisms, impact on outcomes and treatment of anemia and iron deficiency in patients with heart failure.

  1. Targeting Iron Deficiency Anemia in Heart Failure.

    Science.gov (United States)

    Saraon, Tajinderpal; Katz, Stuart D

    2016-01-01

    Iron deficiency is common in heart failure (HF) patients, and is associated with increased risk of adverse clinical outcomes. Clinical trials of intravenous iron supplementation in iron-deficient HF patients have demonstrated short-term improvement in functional capacity and quality of life. In some trials, the benefits of iron supplementation were independent of the hemoglobin levels. Additional investigations of iron supplementation are needed to characterize the mechanisms contributing to clinical benefit and long-term safety in HF.

  2. Dietary restriction causing iodine-deficient goitre.

    Science.gov (United States)

    Cheetham, Tim; Plumb, Emma; Callaghan, James; Jackson, Michael; Michaelis, Louise

    2015-08-01

    Iodine-deficient goitre was common in some parts of the UK prior to the introduction of salt iodisation. Many contemporary salt preparations do not contain much iodine, and there are renewed concerns about the iodine status of the population. We present a boy with severe allergy who developed goitre and significant thyroid dysfunction in association with an iodine-deficient 'food-restricted' diet. The case highlights the importance of a comprehensive nutritional assessment in all children on multiple food restrictions.

  3. Androgen deficiency and metabolic syndrome in men

    OpenAIRE

    Winter, Ashley G; Zhao, Fujun; Lee, Richard K.

    2014-01-01

    Metabolic syndrome (MetS) is a growing health concern worldwide. Initially a point of interest in cardiovascular events, the cluster of HTN, obesity, dyslipidemia, and insulin resistance known as MetS has become associated with a variety of other disease processes, including androgen deficiency and late-onset hypogonadism (LOH). Men with MetS are at a higher risk of developing androgen deficiency, and routine screening of testosterone (T) is advised in this population. The pathophysiology of ...

  4. Colour vision deficiency and physics teaching

    Science.gov (United States)

    Maule, Louise; Featonby, David

    2016-05-01

    1 in 12 males suffer from some form of colour vision deficiency (CVD) which in the present colour dominated world of education presentation can be a severe disadvantage. Although aware of ‘colourblindness’ most teachers make little or no adjustment for these pupils for whom tasks may be more difficult. This article examines colour vision deficiency and looks at ways in which we can help the many students who have this problem.

  5. Severe Vitamin D Deficiency Causing Kyphoscoliosis

    OpenAIRE

    Singhai, Abhishek; Banzal, Subodh

    2013-01-01

    Vitamin D deficiency is common among Indian population. Women are especially at risk for severe vitamin D deficiency. The risk is higher for those who are multiparous and postmenopausal. Poor exposure to sunlight, higher latitude, winter season, inadequate diet, older age, obesity and malabsorption are also important risk factors. Symptoms of hypovitaminosis D, including diffuse or migratory pain affecting several sites (especially the shoulder, pelvis, ribcage and lower back) have also been ...

  6. Iron deficiency or anemia of inflammation?

    OpenAIRE

    Nairz, Manfred; Theurl, Igor; Wolf, Dominik; Weiss, Günter

    2016-01-01

    Summary Iron deficiency and immune activation are the two most frequent causes of anemia, both of which are based on disturbances of iron homeostasis. Iron deficiency anemia results from a reduction of the body’s iron content due to blood loss, inadequate dietary iron intake, its malabsorption, or increased iron demand. Immune activation drives a diversion of iron fluxes from the erythropoietic bone marrow, where hemoglobinization takes place, to storage sites, particularly the mononuclear ph...

  7. An Approach to Iron-Deficiency Anemia

    Directory of Open Access Journals (Sweden)

    Imran Rasul

    2001-01-01

    Full Text Available Iron-deficiency anemia is a common reason for referral to a gastroenterologist. In adult men and postmenopausal women, gastrointestinal tract pathology is often the cause of iron-deficiency anemia, so patients are frequently referred for endoscopic evaluation. Endoscopy may be costly and at times difficult for the patient. Therefore, physicians need to know what lesions can be identified reliably and, more importantly, the importance of ruling out life-threatening conditions such as occult malignancy. Over the past decade, a number of prospective studies have been completed that examined the yield of endoscopy in the investigation of iron-deficiency anemia. The present article provides a broad overview of iron-deficiency anemia, with particular emphasis on hematological diagnosis, etiology, the use of endoscopy in identifying lesions and iron-repletion therapy. Other clinical scenarios, including assessment of patients on anti-inflammatory or anticoagulation therapy and patients with bleeding of obscure origin, are also addressed. The present article provides a diagnostic algorithm to iron-deficiency anemia, which describes a more systematic manner in which to approach iron-deficiency anemia.

  8. Recognition and management of vitamin D deficiency.

    Science.gov (United States)

    Bordelon, Paula; Ghetu, Maria V; Langan, Robert C

    2009-10-15

    Vitamin D deficiency affects persons of all ages. Common manifestations of vitamin D deficiency are symmetric low back pain, proximal muscle weakness, muscle aches, and throbbing bone pain elicited with pressure over the sternum or tibia. A 25-hydroxyvitamin D level should be obtained in patients with suspected vitamin D deficiency. Deficiency is defined as a serum 25-hydroxyvitamin D level of less than 20 ng per mL (50 nmol per L), and insufficiency is defined as a serum 25-hydroxyvitamin D level of 20 to 30 ng per mL (50 to 75 nmol per L). The goal of treatment is to normalize vitamin D levels to relieve symptoms and decrease the risk of fractures, falls, and other adverse health outcomes. To prevent vitamin D deficiency, the American Academy of Pediatrics recommends that infants and children receive at least 400 IU per day from diet and supplements. Evidence shows that vitamin D supplementation of at least 700 to 800 IU per day reduces fracture and fall rates in adults. In persons with vitamin D deficiency, treatment may include oral ergocalciferol (vitamin D2) at 50,000 IU per week for eight weeks. After vitamin D levels normalize, experts recommend maintenance dosages of cholecalciferol (vitamin D3) at 800 to 1,000 IU per day from dietary and supplemental sources.

  9. [Approaches to vitamin B12 deficiency].

    Science.gov (United States)

    Russcher, Henk; Heil, Sandra G; Slobbe, Lennert; Lindemans, Jan

    2012-01-01

    A 28-year-old female vegetarian was referred to a specialist in internal medicine with persistent iron deficiency. Laboratory analysis revealed microcytic anaemia with low ferritin levels but normal total vitamin B12 levels. The red blood cell distribution width, however, showed a very wide variation in red blood cell sizes, indicating a coexisting vitamin B12 deficiency, which was confirmed by the low concentration of active vitamin B12. Another patient, a 69-year-old woman with a history of previous gastric surgery and renal insufficiency as a complication of diabetes mellitus, was suspected to be deficient in vitamin B12, as she had low total vitamin B12 levels and an accumulation of methylmalonic acid and homocysteine in her blood. Testing the total concentration of vitamin B12 alone has insufficient diagnostic accuracy and no accepted gold standard is available for diagnosing vitamin B12 deficiency. With the development of newer tests, such as measuring holotranscobalamin II (concentration of active vitamin B12), atypical and subclinical deficiency states can be recognized. A new approach to diagnosing vitamin B12 deficiency is presented, based upon these 2 case descriptions.

  10. Oxidative dehydrogenation of n-butane over vanadium magnesium oxide catalysts supported on nano-structured MgO and ZrO2: effect of oxygen capacity of the catalyst.

    Science.gov (United States)

    Lee, Howon; Lee, Jong Kwon; Hong, Ung Gi; Song, In Kyu; Yoo, Yeonshick; Cho, Young-Jin; Lee, Jinsuk; Chang, Hosik; Jung, Ji Chul

    2012-07-01

    Vanadium-magnesium oxide catalysts supported on nano-structured MgO and ZrO2 (Mg3(VO4)2/MgO/ZrO2) were prepared by a wet impregnation method with a variation of Mg:Zr ratio (8:1, 4:1, 2:1, and 1:1). For comparison, Mg3(VO4)2/MgO and Mg3(VO4)2/ZrO2 catalysts were also prepared by a wet impregnation method. The prepared catalysts were applied to the oxidative dehydrogenation of n-butane in a continuous flow fixed-bed reactor. Mg3(VO4)2/MgO/ZrO2 (Mg:Zr = 4:1, 2:1, and 1:1) and Mg3(VO4)2/ZrO2 catalysts showed a stable catalytic activity during the whole reaction time, while Mg3(VO4)2/MgO/ZrO2 (8:1) and Mg3(VO4)2/MgO catalysts experienced a severe catalyst deactivation. Deactivation of Mg3(VO4)2/MgO/ZrO2 (8:1) and Mg3(VO4)2/MgO catalysts was due to their low oxygen mobility. Effect of oxygen capacity (the amount of oxygen in the catalyst involved in the reaction) of the supported Mg3(V04)2 catalysts on the catalytic performance in the oxidative dehydrogenation of n-butane was investigated. Experimental results revealed that oxygen capacity of the catalyst was closely related to the catalytic activity in the oxidative dehydrogenation of n-butane. A large oxygen capacity of the catalyst was favorable for obtaining a high catalytic activity in this reaction. Among the catalysts tested, Mg3(VO4)2/MgO/ZrO2 (4:1) catalyst with the largest oxygen capacity showed the best catalytic performance.

  11. Lower limb deficient children in the Netherlands : epidemiological aspects

    NARCIS (Netherlands)

    Rijnders, LJM; Boonstra, AM; Groothoff, JW; Cornel, MC; Eisma, WH

    2000-01-01

    information on the characteristics of children with limb deficiencies and amputations in the Netherlands is largely lacking. The present study aimed to collect data about the prevalence of congenital deficiencies, the ratio of congenital to acquired limb deficiencies, types of lower leg deficiency o

  12. Structural characterization and oxidative dehydrogenation activity of V2O5/Ce(x)Zr(1-x)O2/SiO2 catalysts.

    Science.gov (United States)

    Reddy, Benjaram M; Lakshmanan, Pandian; Loridant, Stéphane; Yamada, Yusuke; Kobayashi, Tetsuhiko; López-Cartes, Carlos; Rojas, Teresa C; Fernandez, Asunción

    2006-05-11

    The thermal stability of a nanosized Ce(x)Zr(1-x)O2 solid solution on a silica surface and the dispersion behavior of V2O5 over Ce(x)Zr(1-x)O2/SiO2 have been investigated using XRD, Raman spectroscopy, XPS, HREM, and BET surface area techniques. Oxidative dehydrogenation of ethylbenzene to styrene was performed as a test reaction to assess the usefulness of the VOx/Ce(x)Zr(1-x)O2/SiO2 catalyst. Ce(x)Zr(1-x)O2/SiO2 (1:1:2 mol ratio based on oxides) was synthesized through a soft-chemical route from ultrahigh dilute solutions by adopting a deposition coprecipitation technique. A theoretical monolayer equivalent to 10 wt % V2O5 was impregnated over the calcined Ce(x)Zr(1-x)O2/SiO2 sample (773 K) by an aqueous wet impregnation technique. The prepared V2O5/Ce(x)Zr(1-x)O2/SiO2 sample was subjected to thermal treatments from 773 to 1073 K. The XRD measurements indicate the presence of cubic Ce0.75Zr0.25O2 in the case of Ce(x)Zr(1-x)O2/SiO2, while cubic Ce0.5Zr0.5O2 and tetragonal Ce0.16Zr0.84O2 in the case of V2O5/Ce(x)Zr(1-x)O2/SiO2 when calcined at various temperatures. Dispersed vanadium oxide induces more incorporation of zirconium into the ceria lattice, thereby decreasing its lattice size and also accelerating the crystallization of Ce-Zr-O solid solutions at higher calcination temperatures. Further, it interacts selectively with the ceria portion of the composite oxide to form CeVO4. The RS measurements provide good evidence about the dispersed form of vanadium oxide and the CeVO4 compound. The HREM studies show the presence of small Ce-Zr-oxide particles of approximately 5 nm size over the surface of amorphous silica and corroborate with the results obtained from other techniques. The catalytic activity studies reveal the ability of vanadium oxide supported on Ce(x)Zr(1-x)O2/SiO2 to efficiently catalyze the ODH of ethylbenzene at normal atmospheric pressure. The remarkable ability of Ce(x)Zr(1-x)O2 to prevent the deactivation of supported vanadium oxide leading to

  13. [Diagnostic criteria for vitamin D-deficient rickets and hypocalcemia-].

    Science.gov (United States)

    Ozono, Keiichi

    2016-02-01

    Vitamin D deficiency causes rickets or osteomalacia, which is associated with hypomineralization of bone and chondrocytes, and/or hypocalcemia. Accumulating evidence indicates increase in frequency of vitamin D deficiency due to insufficient intake of vitamin D and calcium and decrease in sunshine. It is necessary for clinician to diagnose vitamin D deficiency accurately and treat patients with vitamin D deficiency adequately. For the purpose, clinical guideline or expert opinion on vitamin D deficiency has been reported.

  14. Vitamin K deficiency bleeding in cholestatic infants with alpha-1-antitrypsin deficiency.

    NARCIS (Netherlands)

    Hasselt, P.M. van; Kok, K.F.; Vorselaars, A.D.; Vlerken, L. van; Nieuwenhuys, E.; Koning, T.J. de; Vries, R.A. de; Houwen, R.H.J.

    2009-01-01

    OBJECTIVE: Exclusively breastfed infants with unrecognised cholestatic jaundice are at high risk of a vitamin K deficiency (VKD) bleeding. It is presently unknown whether (the size of) this risk depends on the degree of cholestasis. Since alpha-1-antitrypsin deficiency (A1AD) induces a variable degr

  15. Vitamin K deficiency bleeding in cholestatic infants with alpha-1-antitrypsin deficiency

    NARCIS (Netherlands)

    van Hasselt, P. M.; Kok, K.; Vorselaars, A. D. M.; van Vlerken, L.; Nieuwenhuys, E.; de Koning, T. J.; de Vries, Rindert; Houwen, R. H. J.

    2009-01-01

    Objective: Exclusively breastfed infants with unrecognised cholestatic jaundice are at high risk of a vitamin K deficiency (VKD) bleeding. It is presently unknown whether (the size of) this risk depends on the degree of cholestasis. Since alpha-l-antitrypsin deficiency (A1AD) induces a variable degr

  16. Experimental Copper Deficiency, Chromium Deficiency and Additional Molybdenum Supplementation in Goats – Pathological Findings

    Directory of Open Access Journals (Sweden)

    Frank A

    2001-09-01

    Full Text Available Secondary copper (Cu deficiency, chromium (Cr deficiency and molybdenosis (Mo has been suggested to cause the "mysterious" moose disease in the southwest of Sweden. The present experiment was performed on goats to investigate the clinical, chemical, and pathological alterations after 20 months feeding of a semi-synthetic diet deficient in Cu and Cr. Four groups were included in the study: control group (n = 4, Cu-deficient group (group 1, n = 4, Cr-deficient group (group 2, n = 2 and Cu+Cr-deficient group (group 3, n = 3. Group 3 was additionally supplemented with tetrathiomolybdate during the last 2 months of the experiment. Main histopathological findings in groups 1 and 3 were the lesions in the liver, characterised by a severe active fibrosis, bile duct proliferation, haemosiderosis and mild necroses. Additionally, degenerative alterations of the exocrine pancreas were prominent in groups 1 and 3. Lesions in group 3 were more pronounced than in group 1. In group 3, the skin showed an atrophic dermatosis, while in group 2 a crusty dermatitis caused by Candida spp. was observed. This study shows that liver, pancreas and skin are mainly affected by a long term deficiency of copper and the findings are complicated by molybdenum application while chromium deficiency produced no histomorphological effects in our study.

  17. Zinc Deficiency in Humans and its Amelioration

    Directory of Open Access Journals (Sweden)

    Yashbir Singh Shivay

    2015-01-01

    Full Text Available Zinc (Zn deficiency in humans has recently received considerable attention. Global mortality in children under 5 years of age in 2004 due to Zn deficiency was estimated at 4,53,207 as against 6,66,771 for vitamin A deficiency; 20,854 for iron deficiency and 3,619 for iodine deficiency. In humans 2800-3000 proteins contain Zn prosthetic group and Zn is an integral component of zinc finger prints that regulate DNA transcription. Zinc is a Type-2 nutrient, which means that its concentration in blood does not decrease in proportion of the Zn deficiency. Adverse effects of Zn deficiency vary with age: low weight gain, diarrhoea, aneroxia and neurobehavioral disturbances are observed in infants, while skin changes and dwarfism are frequent in toddlers and adolescents. Common manifestations of Zn deficiency among elderly include hypogeusia, chronic non-healing ulcers and recurrent infections.Ameliorative measures of Zn deficiency in humans can be classified in two groups, namely, nutraceutical and biofortification of food grains. Nutraceutical interventions include pharmaceutical supplements, dietary supplements and dietary diversification, while biofortification of food grains can be achieved by genetic modification (GM of crops or by agronomic techniques that include soil or/and foliar fertilization of crops.The major disadvantage of nutraceutical approaches is that the major beneficiaries are urban people and the poor rural masses that need adequate Zn nutrition most are left out. Genetic biofortification of food grains requires large amounts of funds and a fairly long-period of time. Further, a large number of countries have not yet accepted genetically modified (GM foods. On the other hand agronomic biofortification of food grains yields immediate effects and rural and urban people are equally benefitted. Our studies have shown that Zn concentration in cereals (rice, wheat etc and pulses can be considerably increased by soil or/and foliar

  18. 1,2-环己二醇气相催化脱氢制备邻苯二酚的研究%Synthesis of Catechol by Gaseous Catalytic Dehydrogenation of 1,2-Cyclohexanediol

    Institute of Scientific and Technical Information of China (English)

    熊前政; 刘智凌; 陈明; 李玉明; 廖文文; 任伟

    2001-01-01

    探讨了由1,2-环己二醇气相催化脱氢制备邻苯二酚的工艺过程,采用Pd/活性炭为催化剂,在催化剂负荷为0.3 g环己二醇/(g催化剂*h),反应温度300 ℃条件下,环己二醇转化率>90%,邻苯二酚选择性>85%。产物采用溶剂萃取,产品含量w(邻苯二酚)≥99%。%The process of catechol synthesis by gaseous catalytic dehydrogenation of 1,2-cyclohexanediol was researched.Convervion of 1,2-cyclohexandiol and selectivity for catechol were over 90% and 85% respectively.Purity of catechol was over 99% by solvent extraction.

  19. A regioselective synthesis of benzopinacolones through aerobic dehydrogenative α-arylation of the tertiary sp3 C-H bond of 1,1-diphenylketones with aromatic and heteroaromatic compounds.

    Science.gov (United States)

    More, Nagnath Yadav; Jeganmohan, Masilamani

    2015-01-12

    A regioselective synthesis of symmetrical and unsymmetrical benzopinacolones through aerobic dehydrogenative α-arylation at the tertiary sp(3) C-H bond of substituted 1,1-diphenylketones with aromatic and heteroaromatic compounds, in the presence of K2S2O8 in CF3COOH at room temperature, is described. The reaction is proposed to go via a carbocation intermediate, which could be generated directly from cleavage of the sp(3) C-H bond of 1,1-diphenylketone. Subsequent α-arylation was achieved at the methene sp(3) carbon atom of the substituted ketone. A variety of substituted aromatic and heteroaromatic compounds were compatible with this reaction. In addition, benzopinacolones were converted into sterically hindered, tetrasubstituted alkenes and polycyclic aromatic compounds.

  20. THE STUDY ON REDUCIBILITY OF THE CATALYSTS FOR DEHYDROGENATION OF CYCLOHEXANOL BY TEMPERATURE PROGAMMED REDUCTION (TPR)%程序升温还原法研究环己醇脱氢催化剂的还原性

    Institute of Scientific and Technical Information of China (English)

    张明慧; 李伟; 关乃佳; 陶克毅

    2001-01-01

    Reducibility of the catalysts prepared by different constituents, method of preparation, condition of pretreatment and addition of assistants, was studied by temperature programmed reduction (TPR). The results showed that the activity and stability of dehydrogenation of cyclohexanol were be promoted by the suitable reducing condition..%以程序升温还原技术(TPR)研究了由不同组成、不同制备方法、不同前处理条件以及加入不同助剂的环己醇脱氢制环己酮新型催化剂的还原性,并与催化反应活性和稳定性相关联.结果表明,采用适当还原条件可显著提高催化剂活性稳定性.

  1. Vitamin D Deficiency in Medical Inpatients: A Retrospective Study of Implications of Untreated Versus Treated Deficiency

    Science.gov (United States)

    Zaidi, Syed Asher Hussain; Singh, Gurjit; Owojori, Olukolade; Kela, Ram; Spoors, Shirley; Abbas, Mohamed; Barton, Florence; Rogers, Caroline

    2016-01-01

    Vitamin D deficiency and insufficiency may further increase fracture risk in patients with decreased bone mineral density. A cross-sectional study on serum vitamin D concentrations in medical inpatients was conducted at Bassetlaw District General Hospital between April 2014 and January 2015 (10 months), and the relationship of serum vitamin D concentrations with calcium and alkaline phosphatase was evaluated. 25-Hydroxyvitamin D immunoassays were used and analyzed in the local laboratory. The total number of patients analyzed was 200, age range 18–99 years, with mean age of 76 years. The most common presentation was found to be fall/collapse. The following cutoff points for serum vitamin D were used: levels ≤30 nmol/L for severe deficiency, >30–50 nmol/L for moderate deficiency, >50–75 nmol/L for mild deficiency, and anything above 75 nmol/L as normal. Of the 209 participants examined, 78 (37.3%) participants had mild vitamin D deficiency, 54 (25.8%) participants had moderate vitamin D deficiency, 68 (32.5%) participants had severe vitamin D deficiency, and 9 (4.3%) participants with low vitamin D levels died during their admission. Of the 122 moderate/severe patients, 70 (57.4%) patients had their vitamin D deficiency treated, according to local Trust guidelines. The study found no relationship between serum calcium levels and vitamin D deficiency, whereas patients’ alkaline phosphatase levels were found to be higher with increased severity of vitamin D deficiency. The study examined the implications of untreated severe/moderate vitamin D deficiency compared to treated deficiency, in terms of the frequency of readmission with similar complaints. It was found that the rate of readmission within one year in patients who were not treated was 57%, compared to 48% in patients whose vitamin D deficiency was treated. Presenting after falls was a recurring theme. It was concluded that even if moderate vitamin D deficiency can be asymptomatic, it is important to

  2. The epidemiology of global micronutrient deficiencies.

    Science.gov (United States)

    Bailey, Regan L; West, Keith P; Black, Robert E

    2015-01-01

    Micronutrients are essential to sustain life and for optimal physiological function. Widespread global micronutrient deficiencies (MNDs) exist, with pregnant women and their children under 5 years at the highest risk. Iron, iodine, folate, vitamin A, and zinc deficiencies are the most widespread MNDs, and all these MNDs are common contributors to poor growth, intellectual impairments, perinatal complications, and increased risk of morbidity and mortality. Iron deficiency is the most common MND worldwide and leads to microcytic anemia, decreased capacity for work, as well as impaired immune and endocrine function. Iodine deficiency disorder is also widespread and results in goiter, mental retardation, or reduced cognitive function. Adequate zinc is necessary for optimal immune function, and deficiency is associated with an increased incidence of diarrhea and acute respiratory infections, major causes of death in those diversification. It is widely accepted that intervention in the first 1,000 days is critical to break the cycle of malnutrition; however, a coordinated, sustainable commitment to scaling up nutrition at the global level is still needed. Understanding the epidemiology of MNDs is critical to understand what intervention strategies will work best under different conditions.

  3. Clinical implications of vitamin D deficiency

    Directory of Open Access Journals (Sweden)

    Beata Matyjaszek-Matuszek

    2015-06-01

    Full Text Available Vitamin D deficiency is a common medical problem worldwide and its prevalence rises along with latitude, obesity, sedentary lifestyle, limited sunlight exposure and aging. A great body of evidence has shown that patients with vitamin D deficiency have increased cardiovascular risks and total mortality. Conversely, the presence of comorbidities progressive with age such as abdominal obesity, insulin resistance, type 2 diabetes and hypertension places the patients at an increased risk of vitamin D deficiency. The multidirectional effect of vitamin D deficiency is present in different phases of the aging process. Based on the literature review, the risk factors for vitamin D insufficiency most often found in post-menopausal women include limited sun exposure and time spent outdoors, inadequate dietary vitamin D intake, winter season and increased age. Vitamin D supplementation in this group might offer prevention of falls and fractures and may be beneficial for cardiovascular health, what may be especially important in osteoporotic and elderly populations. Prevention and treatment processes involve education regarding sunlight exposure and pharmacological cholecalciferol supplementation according to the recommendations for Central Europe. This manuscript reviews the role of vitamin D and its deficiency and considers their clinical implications, with particular regard to peri- and postmenopausal women.

  4. Biochemical Assessment of Coenzyme Q10 Deficiency

    Directory of Open Access Journals (Sweden)

    Juan Carlos Rodríguez-Aguilera

    2017-03-01

    Full Text Available Coenzyme Q10 (CoQ10 deficiency syndrome includes clinically heterogeneous mitochondrial diseases that show a variety of severe and debilitating symptoms. A multiprotein complex encoded by nuclear genes carries out CoQ10 biosynthesis. Mutations in any of these genes are responsible for the primary CoQ10 deficiency, but there are also different conditions that induce secondary CoQ10 deficiency including mitochondrial DNA (mtDNA depletion and mutations in genes involved in the fatty acid β-oxidation pathway. The diagnosis of CoQ10 deficiencies is determined by the decrease of its content in skeletal muscle and/or dermal skin fibroblasts. Dietary CoQ10 supplementation is the only available treatment for these deficiencies that require a rapid and distinct diagnosis. Here we review methods for determining CoQ10 content by HPLC separation and identification using alternative approaches including electrochemical detection and mass spectrometry. Also, we review procedures to determine the CoQ10 biosynthesis rate using labeled precursors.

  5. Caspase 12 in calnexin-deficient cells.

    Science.gov (United States)

    Groenendyk, Jody; Zuppini, Anna; Shore, Gordon; Opas, Michal; Bleackley, R Chris; Michalak, Marek

    2006-11-07

    We investigated a role for calnexin, caspase 12, and Bap31 in endoplasmic reticulum stress-induced apoptosis in calnexin-deficient mouse embryonic fibroblasts and a calnexin-deficient human T cell line (NKR). We showed that calnexin-deficient mouse embryonic fibroblasts are relatively resistant to endoplasmic reticulum stress-induced apoptosis. Western blot analysis demonstrated that both wild-type and calnexin-deficient cells contained a caspase 12 protein. Caspase 12 expression was slightly inhibited in calnexin-deficient cells, and the protein carried out specific cleavage in the presence of thapsigargin. Immunoprecipitation experiments revealed that in the endoplasmic reticulum, caspase 12 forms complexes with Bap31 and calnexin. Treatment of wild-type cells with thapsigargin induced apoptosis and cleavage of Bap31. However, in the absence of calnexin, there was no significant cleavage of Bap31. There was also a negligible processing of caspase 8 in these cells. This work indicates that calnexin may play a role in modulating the sensitivity of a cell to apoptosis induced by endoplasmic reticulum stress, in conjunction with caspase 12 and Bap31.

  6. Study on a Controllable Oxidative Dehydrogenation of Butene in a Novel Inorganic Membrane Reactor%膜控制氧化反应器中丁烯氧化脱氢的研究

    Institute of Scientific and Technical Information of China (English)

    李志华; 刘长厚; 王连军; 葛善海

    2001-01-01

    在气体均布的无机膜控制氧化反应器上进行了丁烯氧化脱氢制丁二烯反应,并将其与固定床方式反应的实验结果进行了对比,结果表明在实验范围内膜反应器比传统的固定床反应更为有效。建立了描述控制氧化膜反应器操作性能的数学模型,并将模型求解值与实验值对比,吻合良好。%Controllable oxidative dehydrogenation of butene to butadiene was carried out in a novel inorganic membrane reactor(IMR) with oxygen uniform distribution. In this reactor butene and air (oxygen) were introduced into the two sides of the membrane separately. By means of adjusting the pressure difference across the membrane the permeation of air into the reaction region was controllable. The main reaction was promoted and the excessive oxidation of the hydrocarbons is eliminated. The experimental result showed that both the yield and selectivity of the butadiene obtained in the IMR were higher than those obtained in FBR obviously. The kinetic equations of oxidative dehydrogenation of butene over a ferrite catalyst were suggested and the mathematical model for simulating the operation characteristic of IMR was derived. The simulating results agree well with the experimental results. It appears that this kind of reactor can be used for other oxidation reactions.

  7. 废铝旋转喷吹除氢的水模拟试验与熔炼实验验证%Water-simulation experiment of scrap aluminium dehydrogenation by rotating impeller degassing and melting experiment verification

    Institute of Scientific and Technical Information of China (English)

    李聪; 龙思远; 杨怀德; 范超; 逯志浩

    2013-01-01

    In order to explore the optimization process combination of dehydrogenation by rotating impeller degassing technology for molten scrap aluminum, the water-simulation experiments were made from the source of hydrogen in molten aluminum and with Approximation Principle as guidance. Then with results of water-simulation experiments for reference, dehydrogenation experiments for smelting aluminum scrap were accomplished. By analyzing the experimental effect, it is shown that the hydrogen content is decreased from 0.30 mL/100 g to 0.11 mL/100 g, and the experimental results of rotor offset distribution are obviously superior to that of rotor center distribution. So the accuracy of optimizing process combination of water-simulation experiment is verified.%为探索废铝熔体旋转喷吹除氢的优化工艺组合,从氢的来源入手,以相似原理为指导,进行旋转喷吹的水模拟试验,然后以水模拟试验结果为参考,进行废铝的熔炼除氢实验,并分析其除氢效果.结果表明:转子偏置分布实验中,氢的质量浓度从0.30 mL/100 g降至0.11 mL/100 g,效果明显优于转子中心分布实验,从而验证水模拟试验的优化工艺组合的准确性.

  8. Discrepancias en los Cálculos Termodinámicos Relacionados con la Deshidrogenación de Parafinas Differences in Thermodynamic Calculations Related to the Dehydrogenation of Paraffins

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    Rosario Caicedo-Realpe

    2009-01-01

    Full Text Available En este artículo se presentan las diferencias existentes entre las constantes de equilibrio y las conversiones, para la deshidrogenación de parafinas, calculadas por tres diferentes métodos y los valores tradicionalmente aceptados en la literatura. Usualmente se ha considerado que la conversión en el equilibrio, en la deshidrogenación de parafinas, aumenta con el número de carbonos de forma monotónica. Sin embargo, las conversiones calculadas en este trabajo, correspondientes a las parafinas C3 hasta C10, oscilan entre el 15 y el 20%, y sólo a partir de C11 se nota un incremento con el número de carbonos, pero que no llega a ser de la misma magnitud que la tendencia aceptada. Esta tendencia ampliamente mencionada en la literatura científica difiere de los resultados obtenidos en este trabajo por lo que se concluye que la aceptada tendencia entre conversión de equilibro y numero de carbonos, no es correcta.In this paper, the differences between the equilibrium constants and conversions, for the dehydrogenation of paraffins, calculated by three methods and the values traditionally accepted in the literature are presented. Usually, it is accepted that the equilibrium conversions, for the dehydrogenation of paraffins, increase with the number of carbons in a monotonous way. However, the conversions calculated in this work for paraffins from C3 to C10, oscillate between 15 and 20%, and only from C11 a similar trend to the traditionally reported values is observed. The trend widely mentioned in the scientific literature shows important differences with the results obtained in this work, concluding that the accepted tendency between equilibrium conversion and number of carbons is not correct.

  9. Multispectral Analysis of Color Vision Deficiency Tests

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    Sergejs FOMINS

    2011-03-01

    Full Text Available Color deficiency tests are usually produced by means of polygraphy technologies and help to diagnose the type and severity of the color deficiencies. Due to different factors, as lighting conditions or age of the test, standard characteristics of these tests fail, thus not allowing diagnosing unambiguously the degree of different color deficiency. Multispectral camera was used to acquire the spectral images of the Ishihara and Rabkin pseudoisochromatic plates in the visible spectrum. Spectral data was converted to cone signals, and successive mathematics applied to provide a simple simulation of the test performance. Colorimetric data of the each pixel of the test image can be calculated and distribution of color coordinates is presented.http://dx.doi.org/10.5755/j01.ms.17.1.259

  10. Experimental models of melatonin-deficient hypertension.

    Science.gov (United States)

    Simko, Fedor; Reiter, Russel J; Pechanova, Olga; Paulis, Ludovit

    2013-01-01

    Melatonin secreted by the pineal gland plays an important role in the regulation of blood pressure (BP) and its administration reduces hypertension both in animals and humans. There are two experimental models of melatonin-deficient hypertension: one induced by pinealectomy and another by continuous 24 hour exposure to light. Both models cause melatonin deficiency and prevent darkness-mediated nocturnal melatonin secretion and are associated with increased BP and myocardial, vascular and renal dysfunction. These models also lead to neurohumoral activation of the renin-angiotensin system, sympathetic nervous system, adrenocorticotrophin-glucocorticoid axis and cause insulin resistance. Together, these alterations contribute to rise in blood pressure by vasoconstrictive or circulatory fluid volume overload. The light induced hypertension model mimics the melatonin deficiency in patients with insufficient nocturnal BP decline, in those who have night shift or who are exposed to environmental light pollution. For this reason, this model is useful in development of anti-hypertensive drugs.

  11. Sneddon syndrome associated with Protein S deficiency

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    Refah Sayin

    2012-01-01

    Full Text Available Sneddon syndrome (SS is rare, arterio-occlusive disorder characterized by generalized livedo racemosa of the skin and various central nervous symptoms due to occlusion of medium-sized arteries of unknown. Seizure, cognitive impairment, hypertension, and history of repetitive miscarriages are the other symptoms seen in this disease. Livedo racemosa involves persisting irreversible skin lesions red or blue in color with irregular margins. Usually, SS occurs in women of childbearing age. Protein S deficiency is an inherited or acquired disorder associated with an increased risk of thrombosis. We present a 33-year-old woman with SS with diffuse livedo racemosa, recurrent cerebrovascular diseases, migraine-type headache, sinus vein thrombosis, and protein S deficiency. Protein S deficiency and with Sneddon syndrome rarely encountered in the literature.

  12. Sneddon syndrome associated with Protein S deficiency.

    Science.gov (United States)

    Sayin, Refah; Bilgili, Serap Gunes; Karadag, Ayse Serap; Tombul, Temel

    2012-01-01

    Sneddon syndrome (SS) is rare, arterio-occlusive disorder characterized by generalized livedo racemosa of the skin and various central nervous symptoms due to occlusion of medium-sized arteries of unknown. Seizure, cognitive impairment, hypertension, and history of repetitive miscarriages are the other symptoms seen in this disease. Livedo racemosa involves persisting irreversible skin lesions red or blue in color with irregular margins. Usually, SS occurs in women of childbearing age. Protein S deficiency is an inherited or acquired disorder associated with an increased risk of thrombosis. We present a 33-year-old woman with SS with diffuse livedo racemosa, recurrent cerebrovascular diseases, migraine-type headache, sinus vein thrombosis, and protein S deficiency. Protein S deficiency and with Sneddon syndrome rarely encountered in the literature.

  13. Model of how plants sense zinc deficiency

    DEFF Research Database (Denmark)

    Assuncao, Ana G.L.; Persson, Daniel Olof; Husted, Søren;

    2013-01-01

    to develop plant-based solutions addressing nutrient-use-efficiency and adaptation to nutrient-limited or -toxic soils. Recently two transcription factors of the bZIP family (basic-region leucine zipper) have been identified in Arabidopsis and shown to be pivotal in the adaptation response to zinc deficiency....... They represent not only the first regulators of zinc homeostasis identified in plants, but also a very promising starting-point that can provide new insights into the molecular basis of how plants sense and adapt to the stress of zinc deficiency. Considering the available information thus far we propose...... in this review a putative model of how plants sense zinc deficiency....

  14. Ornithine Transcarbamylase Deficiency in Iranian Children

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    HR Joshaghani

    2003-08-01

    Full Text Available Ammonia is a toxic material for mammalians. It is detoxificated and converted to urea in the urea cycle in liver. Each defect in the urea cycle cause increase in blood ammonia level. Ornithine transcarbamylase enzyme (OTC is the second enzyme in the urea cycle that exists in mitochondria. OTC deficiency is the most common hereditary disorder in the urea cycle. In this study, 45 hyper ammonia patients were selected (2-13 years old and assayed for serum OTC, serum aspartate aminotransferase (AST, serum alanine aminotransferase (ALT. Four patients (n=45, 8.9% suffered from OTC deficiency. One patient was male (n=29, 3.4% and the others were female (n=16, 18.8%. About half of children (53.3 with hyper ammonia have liver disease. Further studies on OTC deficiency and OTC gene mutations in Iran are recommended.

  15. MRI findings of complete growth hormone deficiency

    Energy Technology Data Exchange (ETDEWEB)

    Ichiba, Yozo [National Hospital of Okayama (Japan)

    1995-10-01

    Magnetic resonance (MR) imaging was performed on the pituitary gland of 20 children (age range, 2-11 years) with short stature due to growth hormone deficiency. Sixteen patients with multiple pituitary hormone deficiency showed disappearance of the pituitary stalk, disappearance of high signal area of the posterior pituitary, presence of ectopic pituitary, and decreased volume of the anterior pituitary. Many of them had a history of perinatal abnormalities such as asphyxia at delivery, breech delivery, and bradytocia. On the contrary, patients with isolated growth hormone deficiency presented no abnormal findings on MR images, and had no history of perinatal abnormalities. The findings of pituitary stalk separation syndrome suggested the presence of multiple hypopituitarism. (S.Y.).

  16. Vitamin D deficiency in early pregnancy.

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    Shannon K Flood-Nichols

    Full Text Available Vitamin D deficiency is a common problem in reproductive-aged women in the United States. The effect of vitamin D deficiency in pregnancy is unknown, but has been associated with adverse pregnancy outcomes. The objective of this study was to analyze the relationship between vitamin D deficiency in the first trimester and subsequent clinical outcomes.This is a retrospective cohort study. Plasma was collected in the first trimester from 310 nulliparous women with singleton gestations without significant medical problems. Competitive enzymatic vitamin D assays were performed on banked plasma specimens and pregnancy outcomes were collected after delivery. Logistic regression was performed on patients stratified by plasma vitamin D concentration and the following combined clinical outcomes: preeclampsia, preterm delivery, intrauterine growth restriction, gestational diabetes, and spontaneous abortion.Vitamin D concentrations were obtained from 235 patients (mean age 24.3 years, range 18-40 years. Seventy percent of our study population was vitamin D insufficient with a serum concentration less than 30 ng/mL (mean serum concentration 27.6 ng/mL, range 13-71.6 ng/mL. Logistic regression was performed adjusting for age, race, body mass index, tobacco use, and time of year. Adverse pregnancy outcomes included preeclampsia, growth restriction, preterm delivery, gestational diabetes, and spontaneous abortion. There was no association between vitamin D deficiency and composite adverse pregnancy outcomes with an adjusted odds ratio of 1.01 (p value 0.738, 95% confidence intervals 0.961-1.057.Vitamin D deficiency did not associate with adverse pregnancy outcomes in this study population. However, the high percentage of affected individuals highlights the prevalence of vitamin D deficiency in young, reproductive-aged women.

  17. Cited1 deficiency suppresses intestinal tumorigenesis.

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    Valérie Méniel

    Full Text Available Conditional deletion of Apc in the murine intestine alters crypt-villus architecture and function. This process is accompanied by multiple changes in gene expression, including upregulation of Cited1, whose role in colorectal carcinogenesis is unknown. Here we explore the relevance of Cited1 to intestinal tumorigenesis. We crossed Cited1 null mice with Apc(Min/+ and AhCre(+Apc(fl/fl mice and determined the impact of Cited1 deficiency on tumour growth/initiation including tumour multiplicity, cell proliferation, apoptosis and the transcriptome. We show that Cited1 is up-regulated in both human and murine tumours, and that constitutive deficiency of Cited1 increases survival in Apc(Min/+ mice from 230.5 to 515 days. However, paradoxically, Cited1 deficiency accentuated nearly all aspects of the immediate phenotype 4 days after conditional deletion of Apc, including an increase in cell death and enhanced perturbation of differentiation, including of the stem cell compartment. Transcriptome analysis revealed multiple pathway changes, including p53, PI3K and Wnt. The activation of Wnt through Cited1 deficiency correlated with increased transcription of β-catenin and increased levels of dephosphorylated β-catenin. Hence, immediately following deletion of Apc, Cited1 normally restrains the Wnt pathway at the level of β-catenin. Thus deficiency of Cited1 leads to hyper-activation of Wnt signaling and an exaggerated Wnt phenotype including elevated cell death. Cited1 deficiency decreases intestinal tumourigenesis in Apc(Min/+ mice and impacts upon a number of oncogenic signaling pathways, including Wnt. This restraint imposed by Cited1 is consistent with a requirement for Cited1 to constrain Wnt activity to a level commensurate with optimal adenoma formation and maintenance, and provides one mechanism for tumour repression in the absence of Cited1.

  18. Rickets-vitamin D deficiency and dependency

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    Manisha Sahay

    2012-01-01

    Full Text Available Rickets is an important problem even in countries with adequate sun exposure. The causes of rickets/osteomalacia are varied and include nutritional deficiency, especially poor dietary intake of vitamin D and calcium. Non-nutritional causes include hypophosphatemic rickets primarily due to renal phosphate losses and rickets due to renal tubular acidosis. In addition, some varieties are due to inherited defects in vitamin D metabolism and are called vitamin D dependent rickets. This chapter highlights rickets/osteomalacia related to vitamin D deficiency or to inherited defects in vitamin D metabolism. Hypophosphatemic rickets and rickets due to renal tubular acidosis are discussed in other sections of the journal.

  19. Phenylalanine hydroxylase deficiency: diagnosis and management guideline.

    Science.gov (United States)

    Vockley, Jerry; Andersson, Hans C; Antshel, Kevin M; Braverman, Nancy E; Burton, Barbara K; Frazier, Dianne M; Mitchell, John; Smith, Wendy E; Thompson, Barry H; Berry, Susan A

    2014-02-01

    Phenylalanine hydroxylase deficiency, traditionally known as phenylketonuria, results in the accumulation of phenylalanine in the blood of affected individuals and was the first inborn error of metabolism to be identified through population screening. Early identification and treatment prevent the most dramatic clinical sequelae of the disorder, but new neurodevelopmental and psychological problems have emerged in individuals treated from birth. The additional unanticipated recognition of a toxic effect of elevated maternal phenylalanine on fetal development has added to a general call in the field for treatment for life. Two major conferences sponsored by the National Institutes of Health held >10 years apart reviewed the state of knowledge in the field of phenylalanine hydroxylase deficiency, but there are no generally accepted recommendations for therapy. The purpose of this guideline is to review the strength of the medical literature relative to the treatment of phenylalanine hydroxylase deficiency and to develop recommendations for diagnosis and therapy of this disorder. Evidence review from the original National Institutes of Health consensus conference and a recent update by the Agency for Healthcare Research and Quality was used to address key questions in the diagnosis and treatment of phenylalanine hydroxylase deficiency by a working group established by the American College of Medical Genetics and Genomics. The group met by phone and in person over the course of a year to review these reports, develop recommendations, and identify key gaps in our knowledge of this disorder. Above all, treatment of phenylalanine hydroxylase deficiency must be life long, with a goal of maintaining blood phenylalanine in the range of 120-360 µmol/l. Treatment has predominantly been dietary manipulation, and use of low protein and phenylalanine medical foods is likely to remain a major component of therapy for the immediate future. Pharmacotherapy for phenylalanine

  20. Zinc and biotin deficiencies after pancreaticoduodenectomy.

    Science.gov (United States)

    Yazbeck, N; Muwakkit, S; Abboud, M; Saab, R

    2010-01-01

    We report zinc and biotin deficiencies after pancreaticoduodenectomy in a 16 year old female presenting clinically with marked alopecia, total body hair loss, dry skin with scales, and maculopathy with significant vision loss. These micronutrient deficiencies likely occurred due to resection of the duodenum and proximal jejunum, sites of primary absorption of several micronutrients and their protein carriers, including zinc and biotin. Early diagnosis is essential to prevent irreversible sequelae. Adequate supplementation of zinc and biotin as well as dietary advice is needed for clinical improvement.