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Synthesis of terephthalic acid via Diels-Alder reactions with ethylene and oxidized variants of 5-hydroxymethylfurfural.  

Science.gov (United States)

Terephthalic acid (PTA), a monomer in the synthesis of polyethylene terephthalate (PET), is obtained by the oxidation of petroleum-derived p-xylene. There is significant interest in the synthesis of renewable, biomass-derived PTA. Here, routes to PTA starting from oxidized products of 5-hydroxymethylfurfural (HMF) that can be produced from biomass are reported. These routes involve Diels-Alder reactions with ethylene and avoid the hydrogenation of HMF to 2,5-dimethylfuran. Oxidized derivatives of HMF are reacted with ethylene over solid Lewis acid catalysts that do not contain strong Brønsted acids to synthesize intermediates of PTA and its equally important diester, dimethyl terephthalate (DMT). The partially oxidized HMF, 5-(hydroxymethyl)furoic acid (HMFA), is reacted with high pressure ethylene over a pure-silica molecular sieve containing framework tin (Sn-Beta) to produce the Diels-Alder dehydration product, 4-(hydroxymethyl)benzoic acid (HMBA), with 31% selectivity at 61% HMFA conversion after 6 h at 190 °C. If HMFA is protected with methanol to form methyl 5-(methoxymethyl)furan-2-carboxylate (MMFC), MMFC can react with ethylene in the presence of Sn-Beta for 2 h to produce methyl 4-(methoxymethyl)benzenecarboxylate (MMBC) with 46% selectivity at 28% MMFC conversion or in the presence of a pure-silica molecular sieve containing framework zirconium (Zr-Beta) for 6 h to produce MMBC with 81% selectivity at 26% MMFC conversion. HMBA and MMBC can then be oxidized to produce PTA and DMT, respectively. When Lewis acid containing mesoporous silica (MCM-41) and amorphous silica, or Brønsted acid containing zeolites (Al-Beta), are used as catalysts, a significant decrease in selectivity/yield of the Diels-Alder dehydration product is observed. PMID:24912153

Pacheco, Joshua J; Davis, Mark E

2014-06-10

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Synthesis of terephthalic acid via Diels-Alder reactions with ethylene and oxidized variants of 5-hydroxymethylfurfural  

Science.gov (United States)

Terephthalic acid (PTA), a monomer in the synthesis of polyethylene terephthalate (PET), is obtained by the oxidation of petroleum-derived p-xylene. There is significant interest in the synthesis of renewable, biomass-derived PTA. Here, routes to PTA starting from oxidized products of 5-hydroxymethylfurfural (HMF) that can be produced from biomass are reported. These routes involve Diels-Alder reactions with ethylene and avoid the hydrogenation of HMF to 2,5-dimethylfuran. Oxidized derivatives of HMF are reacted with ethylene over solid Lewis acid catalysts that do not contain strong Brønsted acids to synthesize intermediates of PTA and its equally important diester, dimethyl terephthalate (DMT). The partially oxidized HMF, 5-(hydroxymethyl)furoic acid (HMFA), is reacted with high pressure ethylene over a pure-silica molecular sieve containing framework tin (Sn-Beta) to produce the Diels-Alder dehydration product, 4-(hydroxymethyl)benzoic acid (HMBA), with 31% selectivity at 61% HMFA conversion after 6 h at 190 °C. If HMFA is protected with methanol to form methyl 5-(methoxymethyl)furan-2-carboxylate (MMFC), MMFC can react with ethylene in the presence of Sn-Beta for 2 h to produce methyl 4-(methoxymethyl)benzenecarboxylate (MMBC) with 46% selectivity at 28% MMFC conversion or in the presence of a pure-silica molecular sieve containing framework zirconium (Zr-Beta) for 6 h to produce MMBC with 81% selectivity at 26% MMFC conversion. HMBA and MMBC can then be oxidized to produce PTA and DMT, respectively. When Lewis acid containing mesoporous silica (MCM-41) and amorphous silica, or Brønsted acid containing zeolites (Al-Beta), are used as catalysts, a significant decrease in selectivity/yield of the Diels-Alder dehydration product is observed. PMID:24912153

Pacheco, Joshua J.; Davis, Mark E.

2014-01-01

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2,5-Dihy­droxy­terephthalic acid dihydrate  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The title compound, C8H6O6·2H2O, was obtained by accident within a project on the synthesis of metal–organic coordination polymers by the reaction of LiOH with 2,5-dihy­droxy­terephthalic acid under solvothermal conditions. The asymmetric unit consists of half a 2,5-dihy­droxy­terephthalic acid mol­ecule located on a centre of inversion and one solvent water mol­ecule that occupies a general position. The 2,5-dihy­droxy­terephthalic acid mol­ecules are connected to the water mol­...

Cheng, Po-wen; Cheng, Chi-feng; Chun-ting, Yeh; Lin, Chia-her

2010-01-01

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Synthesis of terephthalic acid via Diels-Alder reactions with ethylene and oxidized variants of 5-hydroxymethylfurfural  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Current, plant-based polyethylene terephthalate (PET) is produced from biomass-derived ethylene glycol [the terephthalic acid (PTA) used is not from biomass]. To have a 100% biomass-derived PET, PTA must be produced from biomass. Here, pathways for the production of renewable PTA, using Diels-Alder reactions between ethylene and oxidized derivatives of 5-hydroxymethylfurfural, a biomass-derived chemical, are reported. These pathways are enabled by new catalytic chemistry that may provide rout...

Pacheco, Joshua J.; Davis, Mark E.

2014-01-01

5

Renal handling of terephthalic acid  

International Nuclear Information System (INIS)

By use of the Sperber in vivo chicken preparation method, infusion of radiolabeled terephthalic acid ([14C]TPA) into the renal portal circulation revealed a first-pass excretion of the unchanged compound into the urine. This model was utilized further to characterize the excretory transport of [14C]TPA and provide information on the structural specificity in the secretion of dicarboxylic acids. At an infusion rate of 0.4 nmol/min. 60% of the [14C]TPA which reached the kidney was directly excreted. An infusion rate of 3 or 6 mumol/min resulted in complete removal of [14C]TPA by the kidney. These results indicate that TPA is both actively secreted and actively reabsorbed when infused at 0.4 nmol/min and that active reabsorption is saturated with the infusion of TPA at higher concentrations. The secretory process was saturated with the infusion of TPA at 40 mumol/mn. The excretory transport of TPA was inhibited by the infusion of probenecid, salicylate, and m-hydroxybenzoic acid, indicating that these organic acids share the same organic anion excretory transport process. m-Hydroxybenzoic acid did not alter the simultaneously measured excretory transport of p-aminohippuric acid (PAH), suggesting that there are different systems involved in the secretion of TPA and PAH. The structural specificity for renal secretion of dicarboxylic acids was revealed by the use of o-phthalic acid and m-phthalic acid as possible inhibitors of TPAhthalic acid as possible inhibitors of TPA secretion

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2,5-Dihy-droxy-terephthalic acid dihydrate.  

Science.gov (United States)

The title compound, C(8)H(6)O(6)·2H(2)O, was obtained by accident within a project on the synthesis of metal-organic coordination polymers by the reaction of LiOH with 2,5-dihy-droxy-terephthalic acid under solvothermal conditions. The asymmetric unit consists of half a 2,5-dihy-droxy-terephthalic acid mol-ecule located on a centre of inversion and one solvent water mol-ecule that occupies a general position. The 2,5-dihy-droxy-terephthalic acid mol-ecules are connected to the water mol-ecules via O-H?O hydrogen bonding to form a layer in the ab plane. PMID:21588257

Cheng, Po-Wen; Cheng, Chi-Feng; Chun-Ting, Yeh; Lin, Chia-Her

2010-01-01

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New crystalline modification of terephthalic acid  

Science.gov (United States)

The new crystalline modification of terephthalic acid can be obtained either from the commercially available triclinic modification by heating at 250°C or directly by a thermal hydrolysis of p-dicyanobenzene. It crystallises in a monoclinic system, space group C2/ m with a=8.940(2), b=10.442(2), c=3.790(1) Å, V=353.7(2) Å3, ?=91.21(3)° and Z=2. Both carboxyl groups of terephthalic acid are coplanar with the phenyl ring. The molecules in the crystal are linked through the hydrogen bonds in the carboxyl groups into infinite chains. The orientational disorder is observed in the carboxyl groups. The structure of the monoclinic form is compared with the structure of both the triclinic modifications.

?led?, M.; Janczak, J.; Kubiak, R.

2001-09-01

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Purified terephthalic acid wastewater biodegradation and toxicity.  

Science.gov (United States)

The biodegradation and toxicity of the purified terephthalic acid (PTA) processing wastewater was researched at NJYZ pilot with the fusant strain Fhhh in the carrier activated sludge process (CASP). Sludge loading rate (SLR) for Fhhh to COD of the wastewater was 1.09 d(-1) and to PTA in the wastewater was 0.29 d(-1). The results of bioassay at the pilot and calculation with software Ebis3 showed that the 48h-LC50 (median lethal concentration) to Daphnia magna for the PTA concentration in the wastewater was only 1/10 of that for the chemical PTA. There were 5 kinds of benzoate pollutants and their toxicities existing in the wastewater at least. The toxicity parameter value of the pure chemical PTA cannot be used to predicate the PTA wastewater toxicity. The toxicity of the NJYZ PTA wastewater will be discussed in detail in this paper. PMID:16313024

Zhang, Xu-xiang; Wan, Yu-qiu; Cheng, Shu-pei; Sun, Shi-lei; Zhu, Cheng-jun; Li, Wei-xin; Zhang, Xiao-chun; Wang, Gui-lin; Lu, Jian-hua; Luo, Xiang; Gu, Ji-dong

2005-01-01

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The renal handling of terephthalic acid.  

Science.gov (United States)

By use of the Sperber in vivo chicken preparation method (1948, Ann. R. Agric. Coll. Swed. 15, 317-349), infusion of radiolabeled terephthalic acid ([14C]TPA) into the renal portal circulation revealed a first-pass excretion of the unchanged compound into the urine. This model was utilized further to characterize the excretory transport of [14C]TPA and provide information on the structural specificity in the secretion of dicarboxylic acids. At an infusion rate of 0.4 nmol/min. 60% of the [14C]TPA which reached the kidney was directly excreted. An infusion rate of 3 or 6 mumol/min resulted in complete removal of [14C]TPA by the kidney. These results indicate that TPA is both actively secreted and actively reabsorbed when infused at 0.4 nmol/min and that active reabsorption is saturated with the infusion of TPA at higher concentrations. The secretory process was saturated with the infusion of TPA at 40 mumol/mn. The excretory transport of TPA was inhibited by the infusion of probenecid, salicylate, and m-hydroxybenzoic acid, indicating that these organic acids share the same organic anion excretory transport process. m-Hydroxybenzoic acid did not alter the simultaneously measured excretory transport of p-aminohippuric acid (PAH), suggesting that there are different systems involved in the secretion of TPA and PAH. The structural specificity for renal secretion of dicarboxylic acids was revealed by the use of o-phthalic acid and m-phthalic acid as possible inhibitors of TPA secretion. m-Phthalate, but not o-phthalate, inhibited TPA excretory transport, indicating that there is some specificity in the renal secretion of carboxy-substituted benzoic acids. TPA was actively accumulated by rat and human cadaver renal cortical slices. PMID:3966238

Tremaine, L M; Quebbemann, A J

1985-01-01

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Dibenzyl Terephthalate  

Science.gov (United States)

The WebWare molecule for January is from the article "Chemical Recycling of Pop Bottles: The Synthesis of Dibenzyl Terephthalate from the Plastic Polyethylene Terephthalate" by Craig J. Donahue, Jennifer A. Exline, and Cynthia Warner. Polyethylene terephthalate from 2-liter pop bottles can be recycled by converting it to dibenzyl terephthalate.

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Synthesis and characterizations of degradable aliphatic-aromatic copolyesters from lactic acid, dimethyl terephthalate and diol: Effects of diol type and monomer feed ratio  

Directory of Open Access Journals (Sweden)

Full Text Available Lactic acid-based aliphatic/aromatic copolyesters are synthesized to incorporate the degradability of polylactic acid and good mechanical properties of aromatic species by using polycondensation of lactic acid (LA, dimethyl terephthalate (DMT, and various diols. Effects of diol lengths and comonomer feed ratios on structure and properties of the resulting copolymers are investigated. Three types of diols with different methylene lengths are employed, i.e., ethylene glycol (EG, 1,3-propanediol (PD and 1,4-butanediol (BD. LA/DMT/diol feed ratios of 2:1:2, 1:1:2, and 1:2:4 are used in each diol system. It is found that types of the diols play an important role in the properties of the copolyester, where an increase in diol length results in an increase in the copolymers molecular weight, and a decrease in Tg, Tm and crystallinity, when a constant monomer feed ratio is employed. Monomer feed ratio also has a significant effect on properties of the copolymers, where an increase in the aromatic content leads to formation of copolymers with higher molecular weight, longer aromatic block sequence and high aromatic to aliphatic ratio in the chain structure. These, in turn, lead to an increase in Tg, Tm, crystallinity and thermal stability of the copolymer samples, and a reduction in their solubility.

2010-07-01

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The Glycolysis of Poly(ethylene terephthalate) Waste: Lewis Acidic Ionic Liquids as High Efficient Catalysts  

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Poly(ethlyene terephthalate) waste from a local market was depolymerized by ethylene glycol (EG) in the presence of Lewis acidic ionic liquids [Bmim]ZnCl3 and the qualitative analysis showed that bis(hydroxyethyl) terephthalate was the main product. Compared with ionic liquid [Bmim]Cl, the Lewis acidic ionic liquids showed highly catalytic activity in the glycolysis of poly(ethylene terephthalate) PET. Significantly, the conversion of PET and the yield of bis(hydroxyethyl) terephthalate were ...

Mi Lin Zhang; Xue Feng Bai; Qun Feng Yue; Lin Fei Xiao

2013-01-01

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Poly (ethylene terephthalate synthesis with catalysts derived from chrysotile asbestos  

Directory of Open Access Journals (Sweden)

Full Text Available The chrysotile asbestos was converted to the forsterite-type compounds by calcination at 740 and 800ºC (F7-740 and F7-800, which were used as a catalyst for the polycondensation of bis(hydroxyethyl terephthalate affording poly (ethylene terephthalate. The obtained forsterite-type compounds did not show any catalytic activity. However, the products obtained by simply treating them with acetic acid significantly promoted the polymerization that produced a THFinsoluble polymer. It was found that the polymer prepared with the acetic acid-treated F7-740 at 160ºC for 2 h showed a 93% yield and the number average molecular weight of 6.4 × 103. The observed catalytic activity was higher than that for the acetic acid-treated magnesium oxide, as well as the typical polycondensation catalysts, such as magnesium acetate and antimony oxide.

Shigeki Habaue

2010-06-01

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2,5-Dibromo­terephthalic acid dihydrate  

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The asymmetric unit of the title compound, C8H4Br2O4·2H2O, contains one half-mol­ecule of 2,5-dibromo­terephthalic acid (DBTA) and one water mol­ecule. The DBTA mol­ecule is centrosymmetric. In the crystal structure, inter­molecular O—H?O hydrogen bonds link the mol­ecules, forming a three-dimensional framework.

Song, Guang-liang; Liu, Shan; Liu, Hua-jun; Zeng, Tao; Zhu, Hong-jun

2008-01-01

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The using of terephthalic acid for obtaining new organic materials  

International Nuclear Information System (INIS)

Full text.The process of preparation of tere phthalates of the elements of Groups I-II, as well as aluminium and zirconium tere phthalates is studied. Obtained tere phthalates were investigated using optical and electronic microscopy, thermogravimetry, IR spectroscopy, x-ray phase and chemical analysis. Besides, decomposition of aluminium and zirconium tere phthalates by means of hydrothermal, thermo vaporous and thermal treatment was studied. Commercial terephthalic and (TA) as well as TA, obtained from autoclave treatment of poly ethyleneterephthalate waste items were used. Synthesized ammonium terephthalate was successfully used in the preparation of materials with new characteristics. Other tere phthalates were obtained by the reaction of aqueous salt solutions of corresponding elements with ammonium terephthalate or tere phthalates of alkaline elements. for elements of I-II Groups individual compounds (tere phthalates) were prepared and identified. Obtained aluminium and zirconium tere phthalates have variable composition, and later decompose to corresponding oxides. After heating aluminium and zirconium tere phthalates at 600 celsius degree amorphous oxides of these elements are formed with particle size of 200-300 nm. further thermal treatment of these compounds up till 1000 celsius degree leads to the formation of crystalline forms of these oxides. In this case we obtain both gamma and particle size of 500-800 nm. for ZrO2 such treatment leads to thZrO2 such treatment leads to the formation of monoclinic crystals with particle size of 500 nm. the use of yttrium oxide in the synthesis of zirconium terephthalate enables us to obtain tetragonal zirconium oxide. From the above mentioned oxides, using the method of slip casting and pressing, we obtain ceramics with high durability. These results show the perspective of the usage of tere phthalates for the preparation of new materials of various purposes in general, and high quality ceramics in particular

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Sequential pyrolysis of plastic to recover polystyrene HCL and terephthalic acid  

Science.gov (United States)

A process of pyrolyzing plastic waste feed streams containing polyvinyl chloride, polyethylene terephthalate, polystyrene and polyethylene to recover polystyrene HCl and terephthalic acid comprising: heating the plastic waste feed stream to a first temperature; adding an acid or base catalyst on an oxide or carbonate support; heating the plastic waste feed stream to pyrolyze polyethylene terephthalate and polyvinyl chloride; separating terephthalic acid or HCl; heating to a second temperature to pyrolyze polystyrene; separating styrene; heating the waste feed stream to a third temperature to pyrolyze polyethylene; and separating hydrocarbons.

Evans, Robert J. (Lakewood, CO); Chum, Helena L. (Arvada, CO)

1995-01-01

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[Kinetic and mechanism of ozonation of terephthalic acid].  

Science.gov (United States)

The effect of ozonation of terephthalic acid (TA) was evaluated, and the kinetic and mechanism of this process were also discussed. The rate constants of TA with ozone and OH radicals calculated by the relative method are (0.047 +/- 0.010) L x (mol x s)(-1) and 2.28 x 10(9) L x (mol x s)(-1), respectively. The above result was in accordance with the apparent reaction rate constant of ozonation of TA when the process was controlled by chemical reaction. Intermediates detected by high-performance liquid chromatography (HPLC) and ion chromatography (IC) included benzoic acid, tartaric acid, formic acid and oxalic acid, therefore the possible destruction pathway of ozonation of TA was proposed on the basis of above results. PMID:19662847

Zang, Xing-Jie; Tong, Shao-Ping; Ma, Chun-An

2009-06-15

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The use of terephthalic acid to the determination and precipitation Sc3+ from the solutions  

International Nuclear Information System (INIS)

The conditions of quantitative determination and precipitation of Sc3+ from solutions by using 0,1M solution of ammonium terephthalate were determined. Obtained results were compared with the results obtained by benzilic and hydroxide methods. The advantage of this method is a fact that terephthalic acid can be regenerated in 100%. (author)

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Use of terephthalic acid to the determination and precipitation Sc/sup 3 +/ from the solutions  

Energy Technology Data Exchange (ETDEWEB)

The conditions of quantitative determination and precipitation of Sc/sup 3 +/ from solutions by using 0,1M solution of ammonium terephthalate were determined. Obtained results were compared with the results obtained by benzilic and hydroxide methods. The advantage of this method is a fact that terephthalic acid can be regenerated in 100%.

Kurpiel, R.; Brzyska, W. (Uniwersytet Marii Curie-Sklodowskiej, Lublin (Poland))

1979-01-01

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Chemical Recycling of Pop Bottles: The Synthesis of Dibenzyl Terephthalate from the Plastic Polyethylene Terephthalate  

Science.gov (United States)

A laboratory procedure involving the chemical recycling of the plastic polyethylene terephthalate (PET or PETE) from 2-L pop bottles is described. A transesterification reaction is employed to depolymerize PET. At atmospheric pressure in refluxing benzyl alcohol in the presence of a catalyst, PET is converted to dibenzyl terephthalate in moderate yields. This procedure models an industrial process that involves the transesterification reaction of PET with methanol at high temperature and pressure, conditions not normally accessible in an undergraduate laboratory, to yield dimethyl terephthalate and ethylene glycol. A second method of preparing dibenzyl terephthalate starting with terephthaloyl chloride is also described. The diester from these two approaches is characterized using melting points, TLC, and IR and NMR spectroscopy. This experiment has been used in a general chemistry sequence that has sections on organic chemistry and polymer chemistry, but is also well suited for an introductory organic chemistry laboratory course or a polymer chemistry laboratory course. This lab experiment is part of a larger effort to develop a general chemistry sequence for engineering students using the theme of chemistry and the automobile. Student results are presented.

Donahue, Craig J.; Exline, Jennifer A.; Warner, Cynthia

2003-01-01

 
 
 
 
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New Titanium-Based Catalysts for the Synthesis of Poly(ethylene terephthalate)  

International Nuclear Information System (INIS)

Poly(ethylene terephthalate) (PET) is a polymer with relatively low cost and high performance, which is widely used in various applications such as bottles, textile fibers, films and engineering plastics for automobiles and electric industries. Commercial catalysts used for synthesis of PET are in general antimony (Sb) compounds. Antimony(III) oxide, antimony(III) acetate and antimony(III) glycolate are used as a catalyst in 95% of PET manufacturing industries worldwide. The few organoantimony compounds that have been identified in environmental and biological samples are all in the form of methylated Sb-species. The Sb trace element is extremely toxic to mammals, and interferes with embryonic and fetal development, also, carcinogenic to humans. In addition to being found in drinking water, food packaging and soft-drink bottles. According to the World Health Organization (WHO), Sb species concentration lower than 20 ppb are acceptable for drinking water. According to a recent study, in 14 brands of bottled water from Canada, Sb concentrations increased on average 19% during 6 months storage at room temperature, but 48 brands of water from 11 European countries increased on average 90% under identical conditions. Therefore, a very important challenge for polyester catalysis is to come-up with a new Sb-free catalysts with low environmental impact. Intensive efforts have been made to find other stable and more environmental friendly non-antimony catalysts, such as those based on titanium. Titanium-based catalysts have been known for many years and actually are used for polybutylene terephthalate (PBT) and polypropylene terephthalate (PPT) production, however, polycondensation (PC) of PET manufacture is not well studied in literature. To date, only few esterification processes have been applied for the synthesis of PET by titanium catalysts. Herein, we report an efficient synthesis characterization and polymerization of PET for a series of new nontoxic organotitanium catalyst. Titanium metal has strong activity in polyesterification and forms stable complex with heteroatom-containing ligands (Scheme 1). These properties of titanium have been used advantageously in simple methods of syntheses and production of inexpensive metal catalyst. The high activity and selectivity of titanium-containing catalysts, their good solubility, and the absence of acidic effluent, which causes corrosion, are the reasons why these catalysts are frequently used in industry

22

A New Esterase from Thermobifida halotolerans Hydrolyses Polyethylene Terephthalate (PET) and Polylactic Acid (PLA)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A new esterase from Thermobifida halotolerans (Thh_Est) was cloned and expressed in E. coli and investigated for surface hydrolysis of polylactic acid (PLA) and polyethylene terephthalate (PET). Thh_Est is a member of the serine hydrolases superfamily containing the -GxSxG- motif with 85–87% homology to an esterase from T. alba, to an acetylxylan esterase from T. fusca and to various Thermobifida cutinases. Thh_Est hydrolyzed the PET model substrate bis(benzoyloxyethyl)terephthalate and PET...

Georg Steinkellner; Karl Gruber; Helmut Schwab; Guebitz, Georg M.; Rosario Diaz Rodriguez; Annemarie Marold; Sabine Zitzenbacher; Anita Dellacher; Katrin Greimel; Doris Ribitsch; Enrique Herrero Acero

2012-01-01

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A New Esterase from Thermobifida halotolerans Hydrolyses Polyethylene Terephthalate (PET and Polylactic Acid (PLA  

Directory of Open Access Journals (Sweden)

Full Text Available A new esterase from Thermobifida halotolerans (Thh_Est was cloned and expressed in E. coli and investigated for surface hydrolysis of polylactic acid (PLA and polyethylene terephthalate (PET. Thh_Est is a member of the serine hydrolases superfamily containing the -GxSxG- motif with 85–87% homology to an esterase from T. alba, to an acetylxylan esterase from T. fusca and to various Thermobifida cutinases. Thh_Est hydrolyzed the PET model substrate bis(benzoyloxyethylterephthalate and PET releasing terephthalic acid and mono-(2-hydroxyethyl terephthalate in comparable amounts (19.8 and 21.5 mmol/mol of enzyme while no higher oligomers like bis-(2-hydroxyethyl terephthalate were detected. Similarly, PLA was hydrolyzed as indicated by the release of lactic acid. Enzymatic surface hydrolysis of PET and PLA led to a strong hydrophilicity increase, as quantified with a WCA decrease from 90.8° and 75.5° to 50.4° and to a complete spread of the water drop on the surface, respectively.

Georg Steinkellner

2012-02-01

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Rapid determination of terephthalic acid in the hydrothermal decomposition product of poly(ethylene terephthalate) by thermochemolysis-gas chromatography in the presence of tetramethylammonium acetate.  

Science.gov (United States)

Thermochemolysis-gas chromatography in the presence of tetramethylammonium acetate was applied to the direct determination of terephthalic acid (TPA) contained in solid decomposition products obtained from the hydrothermal recycling process of poly(ethylene terephthalate) (PET). On the chromatograms of the hydrothermal decomposition products of PET, a sharp peak of the TPA component was clearly observed as its corresponding dimethyl ester formed through the thermochemolysis reaction. Based on the peak intensities, the contents of TPA in the decomposition products were determined precisely and rapidly without using any cumbersome sample pretreatments. PMID:21985932

Ishida, Yasuyuki; Ohsugi, Kei; Taniguchi, Kohei; Ohtani, Hajime

2011-01-01

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The Glycolysis of Poly(ethylene terephthalate Waste: Lewis Acidic Ionic Liquids as High Efficient Catalysts  

Directory of Open Access Journals (Sweden)

Full Text Available Poly(ethlyene terephthalate waste from a local market was depolymerized by ethylene glycol (EG in the presence of Lewis acidic ionic liquids [Bmim]ZnCl3 and the qualitative analysis showed that bis(hydroxyethyl terephthalate was the main product. Compared with ionic liquid [Bmim]Cl, the Lewis acidic ionic liquids showed highly catalytic activity in the glycolysis of poly(ethylene terephthalate PET. Significantly, the conversion of PET and the yield of bis(hydroxyethyl terephthalate were achieved at 100% and 83.8% with low catalyst ([Bmim]ZnCl3 loading (0.16 wt %. Investigation also showed that the catalytic activity of [Bmim]ZnCl3 was higher than that of [Bmim]MnCl3. Catalyst [Bmim]ZnCl3 can be reused up to five times and 1H-NMR results show that the recovered catalyst is similar to the fresh one. A mechanism of the glycolysis of PET catalyzed by [Bmim]ZnCl3 was proposed.

Mi Lin Zhang

2013-11-01

26

Discovery and evaluation of terephthalic acid derivatives as potent alpha4beta1 integrin antagonists.  

Science.gov (United States)

Terephthalic acid based derivatives containing beta- and gamma-amino acid residues were prepared as antagonists of the leukocyte cell adhesion process that is mediated through the interaction of the very late antigen 4 (VLA-4) and the vascular cell adhesion molecule 1 (VCAM-1). The compounds 2, 10-12, 14, and 16-17 inhibited the adhesion in a cell based assay in the low and sub micromolar range. PMID:14567545

Müller, Gerhard; Albers, Markus; Hessler, Gerhard; Lehmann, Thomas E; Okigami, Hiromi; Tajimi, Masaomi; Bacon, Kevin; Rölle, Thomas

2003-08-01

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Polyesters production from the mixture of phthalic acid, terephthalic and glycerol  

International Nuclear Information System (INIS)

Glycerin, a byproduct of biodiesel is currently an environmental and economic problem for producers of this renewable fuel in Brazil and in others parts of the world. In order to offer new proposals for recovery, it is used for the manufacture of polyesters used in applications in diverse areas such as construction and automobile industry. This work reports the production of polymer from the mixture of terephthalic and phthalic acid in three different proportions. The polyesters showed good thermal stability, analyzed by TGA and DSC, with an increase proportional to the terephthalic acid content. The X-ray diffraction patterns show that the samples are semi crystalline polymers. The micrographs indicated the presence of a smoother surface in the polyester that has a larger amount of phthalic acid, as reported in the literature. Therefore, the materials showed good thermal properties and morphological characteristics, so it consists in a new alternative to use glycerin. (author)

28

Corrosion resistance of structural materials in solutions of dichloranhydrides of isophthalic and terephthalic acids  

International Nuclear Information System (INIS)

The production of promising thermally stable polymer materials, i.e., aromatic polyamides of Terlom, Phenylone, and polyarylates is associated with the application of solutions and melts of dichloranhydrides of isophthalic and terephthalic acids. Investigations were carried out on the corrosion resistance, in the melts of the dichloranhydrides of the isophthalic and terephthalic acids, of corrosion-resiting austenitic (12Kh18N10T, 10Kh17N13M2T, 08Kh17N15M3T, 06KhN28MDT), austenitic-ferritic (08Kh22N6T, 08Kh18G2N2T, 08Kh21N6M2T), ferritic (08Kh17T, 15Kh25T) steels and alloys, titanium VT1-0, titanium VT5-1 alloy, and welded joints in these materials. The specimens of the corrosion-resisting steels were welded by the electric arc method using the standard filler materials, and titanium and the titanium alloys were welded by argon-arc welding. On the basis of the experimental results, 08Kh21N6M2T steel and 06KhN28MDT alloy are recommended for the construction of equipment working in the melts of the dichloranhydride of the isophthalic acid, whereas equipment working in the melts of the dichloranhydride of the terephthalic acid at 90 C should be constructed from 08Kh21N6M2T steel

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Preparation of polymer blends from glycerol, fumaric acid and of poly(ethylene terephthalate) (PET) recycled  

International Nuclear Information System (INIS)

Polymer blends based on recycled poly(ethylene terephthalate) (PET) and poly(glycerol fumarate) polyesters were prepared in different PET concentrations. The PET powder was dispersed during the poly(glycerol fumarate) synthesis at 260 deg C. The resulting blends were characterized by X-ray diffraction. The thermal stability of the materials was evaluated by thermogravimetric analysis and differential scanning calorimetry. The morphology was studies by scanning electron microscopy. The blends were clearly immiscible. The possibility of (interfacial) compatibilization of the PET domains, caused by transesterification reactions between PET and glycerol were discussed. (author)

30

The influence of Copolimers Acrylic Acid onto Poli(Etilene Terephthalate)woven fabric  

International Nuclear Information System (INIS)

To improve suitability of wearing poli etilene terephthalate (PET) wovenfabric, it need to enhance the ability in absorbing of water vapour. For theabove reason acrylic acid (AA) has been grafted onto PET wovenfabric(PET-g-AA). Fourier Transform Infrared (FT-IR) data show that poly(acrylic acid) have grafted onto PET woven fabric. Thermal propertiesobtained from DSC (Differential Scanning Calorimeter) measurements of PET-g-AA show that the grafting does not affect bulk properties of PET. Thedecrease of the tensile strength had occurred to PET-g-MMA, however it ratherinfluenced by the reaction time than the initial concentration of acrylicacid. (author)

31

Biodegradability enhancement of purified terephthalic acid wastewater by coagulation-flocculation process as pretreatment.  

Science.gov (United States)

In this work, the coagulation-flocculation process was used as pretreatment for purified terephthalic acid (PTA) wastewater with the objective of improving its overall biodegradability. PTA production generates wastewaters with toxicants p-xylene [1,4-dimethyl-benzene (C8H10)], a major raw material used in the production process, along with some of the intermediates, viz., p-toluic acid, benzoic acid, 4-carboxybenzaldehyde, phthalic acid and terephthalic acid. These compounds affect the bio-oxidation process of wastewater treatment; hence removal of these constituents is necessary, prior to conventional aerobic treatment. This paper addresses the application of coagulation-flocculation process using chemical coagulants, viz., aluminium sulphate (alum), polyaluminium chloride (PAC), ferrous sulphate and ferric chloride in combination with anionic polyelectrolyte. Polyaluminium chloride (PAC) in conjunction with lime and polyelectrolyte removed about 63.1% chemical oxygen demand (COD) and 45.2% biochemical oxygen demand (BOD) from PTA wastewater. Coagulation-flocculation process coupled with aerobic bio-oxidation treatment of PTA wastewater achieved, COD & BOD removals of 97.4% and 99.4%, respectively. The biodegradability enhancement evaluated in terms of the BOD5/COD ratio, increased from 0.45 to 0.67 at the optimum conditions. The results obtained from these studies indicate that the coagulation-flocculation process could be a suitable pretreatment method in reducing toxicity of PTA wastewater whilst enhancing biodegradability for aerobic biological treatment scheme. PMID:18054427

Karthik, Manikavasagam; Dafale, Nishant; Pathe, Pradyumna; Nandy, Tapas

2008-06-15

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Application of several advanced oxidation processes for the destruction of terephthalic acid (TPA).  

Science.gov (United States)

Terephthalic acid (TPA) is widely applied as a raw material in making polyester fiber, polyethylene terephthalate (PET) bottles, polyester films, etc. TPA is toxic and is known to act as endocrine disruptor. TPA wastewater is traditionally treated by biological process and this study aims to evaluate the effectiveness of several advanced oxidation processes on TPA removal. The oxidation processes studied were: UV-TiO(2), UV-H(2)O(2), UV-H(2)O(2)-Fe, O(3), O(3)/Fe, O(3)/TiO(2), UV-O(3)-H(2)O(2)-Fe and UV-O(3)-H(2)O(2)-Fe-TiO(2). The results indicate that the time required for the complete destruction of 50 ppm of TPA can be minimized from 10h using UV-TiO(2) system, to less than 10 min by UV-H(2)O(2)-Fe-O(3) system. Some of the likely organic intermediates identified during TPA destruction include, benzoquinone, benzene, maleic acid and oxalic acid. Possible destruction pathway of TPA has been proposed. TPA degradation by various systems was also analyzed based on the reaction kinetics and operating costs. PMID:17023113

Thiruvenkatachari, Ramesh; Kwon, Tae Ouk; Jun, Jung Chul; Balaji, Subramanian; Matheswaran, Manickam; Moon, Il Shik

2007-04-01

33

Application of several advanced oxidation processes for the destruction of terephthalic acid (TPA)  

Energy Technology Data Exchange (ETDEWEB)

Terephthalic acid (TPA) is widely applied as a raw material in making polyester fiber, polyethylene terephthalate (PET) bottles, polyester films, etc. TPA is toxic and is known to act as endocrine disruptor. TPA wastewater is traditionally treated by biological process and this study aims to evaluate the effectiveness of several advanced oxidation processes on TPA removal. The oxidation processes studied were: UV-TiO{sub 2}, UV-H{sub 2}O{sub 2}, UV-H{sub 2}O{sub 2}-Fe, O{sub 3}, O{sub 3}/Fe, O{sub 3}/TiO{sub 2}, UV-O{sub 3}-H{sub 2}O{sub 2}-Fe and UV-O{sub 3}-H{sub 2}O{sub 2}-Fe-TiO{sub 2}. The results indicate that the time required for the complete destruction of 50 ppm of TPA can be minimized from 10 h using UV-TiO{sub 2} system, to less than 10 min by UV-H{sub 2}O{sub 2}-Fe-O{sub 3} system. Some of the likely organic intermediates identified during TPA destruction include, benzoquinone, benzene, maleic acid and oxalic acid. Possible destruction pathway of TPA has been proposed. TPA degradation by various systems was also analyzed based on the reaction kinetics and operating costs.

Thiruvenkatachari, Ramesh [Department of Chemical Engineering, Sunchon National University, 315 Maegok Dong, Suncheon 540-742, Chonnam (Korea, Republic of); Kwon, Tae Ouk [Department of Chemical Engineering, Sunchon National University, 315 Maegok Dong, Suncheon 540-742, Chonnam (Korea, Republic of); Jun, Jung Chul [Department of Chemical Engineering, Sunchon National University, 315 Maegok Dong, Suncheon 540-742, Chonnam (Korea, Republic of); Balaji, Subramanian [Department of Chemical Engineering, Sunchon National University, 315 Maegok Dong, Suncheon 540-742, Chonnam (Korea, Republic of); Matheswaran, Manickam [Department of Chemical Engineering, Sunchon National University, 315 Maegok Dong, Suncheon 540-742, Chonnam (Korea, Republic of); Moon, Il Shik [Department of Chemical Engineering, Sunchon National University, 315 Maegok Dong, Suncheon 540-742, Chonnam (Korea, Republic of)]. E-mail: ismoon@sunchon.ac.kr

2007-04-02

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Catalytic Synthesis Lactobionic Acid  

Directory of Open Access Journals (Sweden)

Full Text Available Gold nanoparticles are obtained, characterized and deposited on the carrier. Conducted catalytic synthesis of lactobionic acid from lactose. Received lactobionic acid identify on the IR spectrum.

V.G. Borodina

2014-07-01

35

Effect of heat and solvent treatment on radiation grafting of acrylic acid to poly(ethylene terephthalate)  

International Nuclear Information System (INIS)

Direct radiation graft polymerization of acrylic acid onto oriented poly(ethylene terephthalate) films and fibers subjected to thermal treatment and treated with structure-active solvents, such as dichloroethane and dioxane, was studied. Poly(ethylene terephthalate) films and fibers treated with the solvents were irradiated on a 60Co ?-source with doses 10-20 kGy, at dose rates 1-4 kGy/h. Based on the results of thermomechanical analysis, X-ray diffraction, sorption, and acrylic acid grafting, conclusions were drawn concerning the character of structural changes in poly(ethylene terephthalate) exposed to structure-active solvents. The physicochemical properties of the graft copolymers obtained were examined, including the resistance to ?-radiation

36

Effect of oral administration of terephthalic acid on testicular functions of rats  

International Nuclear Information System (INIS)

To investigate the toxic effect of terephthalic acid (TPA) on testicular functions of rats, male Sprague-Dawley rats were orally administered TPA in diet at the levels 0 (control), 0.2, 1 and 5% for 90 days. Testicular functions were assessed by histopathology, testicular sperm head counts, daily sperm production, sperm motility (measured by computer-assisted sperm analysis, CASA), biochemical indices (marker testicular enzymes), and serum testosterone. Oral feeding with terephthalic acid did not cause body and testes weight loss in TPA-treated groups. Histopathologically, damages of spermatogenic cells and Sertoli cells were observed by electron microscope, testicular sperm head counts, daily sperm production, and activities of sorbitol dehydrogenase (SDH) were decreased significantly in the 5% TPA group. The motility of spermatozoa was reduced significantly in all treated groups, which was correlated with administration doses. Serum testosterone concentrations were not declined in treated groups. In conclusion, TPA can cause impairment of testicular functions. The primary sites of action may be spermatogenic cells and Sertoli cells. The results of the present study provide first information of TPA on testicular functions in male rats

37

Bimodal electricity generation and aromatic compounds removal from purified terephthalic acid plant wastewater in a microbial fuel cell.  

Science.gov (United States)

Wastewater of purified terephthalic acid (PTA) from a petrochemical plant was examined in a membrane-less single chamber microbial fuel cell for the first time. Time course of voltage during the cell operation cycle had two steady phases, which refers to the fact that metabolism of microorganisms was shifted from highly to less biodegradable carbon sources. The produced power density was 31.8 mW m(-2) (normalized per cathode area) and the calculated coulombic efficiency was 2.05 % for a COD removal of 74 % during 21 days. The total removal rate of different pollutants in the PTA wastewater was observed in the following order: (acetic acid) > (benzoic acid) > (phthalic acid) > (terephthalic acid) > (p-toluic acid). The cyclic voltammetry results revealed that the electron transfer mechanism was dominated by mediators which were produced by bacteria. PMID:23076363

Marashi, Seyed Kamran Foad; Kariminia, Hamid-Reza; Savizi, Iman Shahidi Pour

2013-02-01

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Modification of N-Methyl-N-Nitrosourea initiated bladder carcinogenesis in Wistar rats by terephthalic acid  

International Nuclear Information System (INIS)

The effect of terephthalic acid (TPA) on urinary bladder carcinogenesis was examined. Male Wistar rats were initiated by injection of N-Methyl-N-Nitrosourea (MNU) (20 mg/kg b.w. ip) twice a week for 4 weeks, then given basal diet containing 5% TPA, 5% TPA plus 4% Sodium bicarbonate (NaHCO3) or 1% TPA for the next 22 weeks, and then euthanized. 5% TPA treatment induced a high incidence of urinary bladder calculi and a large amount of precipitate. Though 5% TPA plus 4% Sodium bicarbonate (NaHCO3) and 1% TPA treatment did not induce urinary bladder calculi formation, they resulted in a moderate increase in urinary precipitate. Histological examination of urinary bladder revealed that MNU-5% TPA treatment resulted in a higher incidence of simple hyperplasia, papillary or nodular hyperplasia (PN hyperplasia), papilloma and cancer than MNU control. MNU-5% TPA plus 4% Sodium bicarbonate (NaHCO3) and 1% TPA treatment increased slightly the incidence of simple hyperplasia and PN hyperplasia (not statistically significant). The major elements of the precipitate are phosphorus, potassium, sulfur, chloride, calcium and TPA. The present study indicated that the calculi induced by TPA had a strong promoting activity on urinary bladder carcinogenesis and the precipitate containing calcium terephthalate (CaTPA) may also have weak promoting activity on urinary bladder carcinogenesis

39

?-radiation-induced graft copolymerization of acrylic acid onto poly (ethylene terephthalate) films: A study by thermal analysis  

International Nuclear Information System (INIS)

The grafting of acrylic acid onto poly (ethylene terephthalate) films with ? radiation was carried out. The effects of different parameters, such as the monomer concentration, inhibitor concentration, and irradiation dose, on the grafting yield were investigated. The grafting yield depended on these parameters, and its maximum value was obtained at a 1.5% inhibitor concentration and a 40%, monomer concentration. The obtained grafting films were characterized with water swelling measurements, differential scanning, calorimetry, and thermogravimetric analysis. The results of differential scanning calorimetry showed decreases in the heat capacity step and the glass-transition temperature with increasing grafting yield. The ability of poly (ethylene terephthalate) to crystallize and the size of the crystalline domains were affected by the grafting. The grafted poly(ethylene terephthalate) that was obtained was tested as an ion exchanger for copper, nickel, cobalt, and lead. The capacity of the grafted films for ion recovery was dependent on the grafting yield. (author)

40

Biosynthesis of terephthalic acid, isophthalic acid and their derivatives from the corresponding dinitriles by tetrachloroterephthalonitrile-induced Rhodococcus sp.  

Science.gov (United States)

The nitrilase from Rhodococcus sp. CCZU10-1 catalyses the hydrolysis of dinitriles to acids without the formation of amides and cyanocarboxylic acids. It was induced by benzonitrile and its analogues (tetrachloroterephthalonitrile > ?-caprolactam > benzonitrile > phenylacetonitrile), and had activity towards aromatic nitriles (terephthalonitrile > tetrachloroterephthalonitrile > isophthalonitrile > tetrachloroisophthalonitrile > tetrafluoroterephthalonitrile > benzonitrile). After the optimization, the highest nitrilase induction [311 U/(g DCW)] was achieved with tetrachloroterephthalonitrile (1 mM) in the medium after 24 h at 30 °C after optimum enzyme activity was at pH 6.8 and at 30 °C. Efficient biocatalyst recycling was achieved by cell immobilization in calcium alginate, with a product-to-biocatalyst ratios of 776 g terephthalic acid/g DCW and 630 g isophthalic acid/g DCW. PMID:24101250

He, Yu-Cai; Wu, Ya-Dong; Pan, Xue-He; Ma, Cui-Luan

2014-02-01

 
 
 
 
41

Biodegradability of terephthalic acid in terylene artificial silk printing and dyeing wastewater.  

Science.gov (United States)

As the characteristic pollutant, terephthalic acid (TA) was in charge of 40%-78% of the total COD of terylene artificial silk printing and dyeing wastewater (TPW-water). The studies on biodegradability of TA were conducted in a serial of activated sludge reactors with TPW-water. TA appeared to be readily biodegradable with removal efficiency over 96.5% under aerobic conditions, hardly biodegradable with removal efficiency below 10% under anoxic conditions and slowly biodegradable with a turnover between 31.4% and 56.0% under anaerobic conditions. TA also accounted for the majority of BOD in TPW-water. The process combined by anoxic, anaerobic and aerobic activated sludge reactor was suitable for TA degradation and TPW-water treatment, Further, the aerobic process was essentially much more effective than the anaerobic or anoxic one to degrade TA in TPW-water. PMID:12938976

Guan, Bao-Hong; Wu, Zhong-Biao; Wu, Zu-Ceng; Xu, Gen-Liang; Tan, Tian-En

2003-05-01

42

Preparation and characterization of polymer blends based on recycled PET and polyester derived by terephthalic acid  

International Nuclear Information System (INIS)

Environmentally friendly materials, made from industrial waste, are being increasingly used as a solution to the growing amount of waste generated by society, but also as a cheaper alternative to replace conventional materials for use in construction. In this work were investigated the properties of polymer blends based on recycled PET and a polyester derived from terephthalic acid and glycerin, a co-product of biodiesel. The samples were characterized by XRD, TGA, DSC, FTIR and SEM. The polyester synthesized showed a degradation event near 300 deg C. The blends with higher ratio of PET showed thermal behavior similar to pure PET. The X-ray diffraction showed that the polymer blends are semicrystalline materials. The micrographs presents the presence of a smooth surface, indicating the possibility of miscibility between the arrays. Therefore, the blending makes possible the fabrication of low-cost materials with applications in several areas. (author)

43

Assessing human exposure to phthalic acid and phthalate esters from mineral water stored in polyethylene terephthalate and glass bottles  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract Abstract. Phthalic acid and phthalates esters present a growing interest due to a large use and to their potential toxicity. Polyethylene terephthalate (PET) and glass are both widely used materials for the bottling of drinking water. In this study, phthalic acid (PhA), bis(2-ethylhexyl) phthalate (DEHP), dimethyl phthalate (DMP), diethyl phthalate (DEP), diisobutyl phthalate (DiisoBP) and dibutyl phthalate (DBP) were analyzed in a large pool of Italian bottled water sampl...

Montuori, Paolo; Jover, Eric; Morgantini, Marcello; Bayona, Josep Maria; Triassi, Maria

2008-01-01

44

Analysis of impurities in crude and highly-purified terephthalic acid by capillary electrophoresis  

Directory of Open Access Journals (Sweden)

Full Text Available In this work, a simple and fast capillary electrophoresis method for the simultaneous analysis of 4-carboxybenzaldehyde (4-CBA, p-toluic acid (pTOL and benzoic acid (BZ in industrial batches of crude (CTA and highly-purified (PTA terephthalic acid was developed. The electrophoretic conditions comprise: 20 mmol L-1 tetraborate buffer at pH 9, hydrodynamic injection (5 s/17 kPa, applied voltage of +30 kV and direct UV detection at 200 nm. The concentrations of 4-CBA and pTOL in five batches of CTA and four batches of PTA as determined by the proposed CE methodology were in agreement with the results from gas chromatography and polarography methods in current use in Tereftalatos Mexicanos S.A. (TEMEX. Levels of BZ were determined only by the CE methodology and ranged from 60 - 300 ppm in CTA and 5 - 7 ppm in PTA. Several impurities deriving from the incomplete oxidation of p-xylene were investigated. So far the positive identification of 4-hydroxymethylbenzoic acid was accomplished by comparison with pure standards.

Moraes Maria de Lourdes L.

2004-01-01

45

The induction of bladder stones by terephthalic acid, dimethyl terephthalate, and melamine (2,4,6-triamino-s-triazine) and its relevance to risk assessment.  

Science.gov (United States)

Terephthalic acid (TPA), dimethyl terephthalate (DMT), and melamine (MA) induced calculi and transitional cell hyperplasia in urinary bladders of rats. A high incidence of calculi was induced in weanling rats, but the incidence was much lower in adult rats ingesting the same dietary concentration of the chemical. The dose-response curves for the induction of urolithiasis in weanling rats were extremely steep, consistent with the fact that the formation calculi can occur in urine that is supersaturated, but not in urine that is undersaturated with respect to the stone components. In the cases of TPA and DMT, stones were composed primarily of calcium terephthalate (CaTPA). By determining the solubility of CaTPA, the concentration of TPA that would be required to achieve urinary saturation was calculated, and a conservative estimate of the amount of TPA or DMT that would have to be absorbed in order to induce calculi was derived. TPA and MA induced bladder tumors in rats in chronic feeding studies. However, it is likely that these tumors were secondary to the development of calculi. TPA and MA are apparently nongenotoxic, and they do not appear to be metabolized. Increased cell replication in the urothelium of the bladder caused by chronic physical injury was probably a major factor in the mechanism of induction of bladder tumors by bladder stones. Bladder neoplasms occurred primarily in the high dose groups, and they were usually, although not invariably, associated with stones. The possibility that stones were passed or were lost during processing of tissues for histopathologic examination could explain the absence of calculi from some of the neoplastic bladders. The formation of bladder calculi is an example of a threshold effect. Although there is strong evidence linking bladder stones with the induction of tumors, the existence of thresholds in chemical carcinogenesis continues to be controversial. A decision by the U.S. Environmental Protection Agency concerning the levels of MA allowed to occur in the food chain indicates that data regarding thresholds, even in the case of urolithiasis, are not being utilized in the risk assessment process. PMID:3903881

Heck, H D; Tyl, R W

1985-09-01

46

Chemical recycling of poly(ethylene terephthalate). Application to the synthesis of multiblock copolyesters  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The chemical recycling of the poly(ethylene terephthalate), (PET), has been successfully carried out by glycolysis in the presence of bis (2-hydroxyethyl) terephthalate (BHET) resulting in the formation of hydroxytelechelic oligomers. These oligomers were then treated with carboxytelechelic poly(?-caprolactone) oligomers of Mn = 2300 and Mn = 730 g•mol–1 molecular weight, in the absence or presence of the titanium tetrabutyloxide (Ti(OBu)4) as a catalyst to get multiblock copolyesters. T...

Malek, F.; El Mejjatti, A.; Harit, T.; Riahi, A.; Khiari, R.; Bouabdallah, I.

2014-01-01

47

Synthesis and properties of poly(hexamethylene terephthalate)/multiwall carbon nanotubes nanocomposites  

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Poly(hexamethylene terephthalate) (PHT)/carbon nanotubes (CNT) nanocomposites containing 1% and 3% (w/w) of filler were prepared by two procedures: in situ ring-opening polymerization of hexamethylene terephthalate cyclic oligomers in the presence of CNT and melt blending of PHT/CNT mixtures. Arc discharge multiwalled carbon nanotubes, both pristine (MWCNT) and hydroxyl functionalized (MWCNT-OH), were used. The objective was to evaluate the effect of preparation procedure, n...

Gonza?lez Vidal, Nathalie; Marti?nez Ilarduya Sa?ez Asteasu, Domingo Antxon; Mun?oz Guerra, Sebastia?n; Castell, Pere; Marti?nez, Maria Teresa

2010-01-01

48

0.5 wt.% Pd/C catalyst for purification of terephthalic acid: Irreversible deactivation in industrial plants  

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A systematic study on several spent catalysts, withdrawn from different terephthalic acid purification reactors loaded with the same fresh catalyst (0.5 wt.% Pd/C, type D3065, supplied by Chimet SpA), has been carried out. Spent catalysts characterized by different lifetimes, position in the catalytic bed, sintering degree, and types of contaminant (mainly S, Pb, and Mo) have been investigated by TEM coupled with EDS detection, XRPD, EXAFS spectroscopy, and CO chemisorption. The Pd sinteri...

Lamberti, Carlo; Agostini, Giovanni; Piovano, Andrea; Groppo, Elena Clara; Pellegrini, Riccardo

2011-01-01

49

The selective recycling of mixed plastic waste of polylactic acid and polyethylene terephthalate by control of process conditions  

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The glycolysis of postconsumer polyethylene terephthalate (PET) waste was evaluated with catalysts of zinc acetate, zinc stearate and zinc sulfate, showing that zinc acetate was the most soluble and effective. The chemical recycling by solvolysis of polylactic acid (PLA) and PET waste in either methanol or ethanol was investigated. Zinc acetate as a catalyst was found to be necessary to yield an effective depolymerization of waste PLA giving lactate esters, while with the same reaction condit...

Carne? Sa?nchez, Arnau; Collinson, Simon R.

2011-01-01

50

In situ energy-dispersive X-ray diffraction for the synthesis optimization and scale-up of the porous zirconium terephthalate UiO-66.  

Science.gov (United States)

The synthesis optimization and scale-up of the benchmarked microporous zirconium terephthalate UiO-66(Zr) were investigated by evaluating the impact of several parameters (zirconium precursors, acidic conditions, addition of water, and temperature) over the kinetics of crystallization by time-resolved in situ energy-dispersive X-ray diffraction. Both the addition of hydrochloric acid and water were found to speed up the reaction. The use of the less acidic ZrOCl2·8H2O as the precursor seemed to be a suitable alternative to ZrCl4·xH2O, avoiding possible reproducibility issues as a consequence of the high hygroscopic character of ZrCl4. ZrOCl2·8H2O allowed the formation of smaller good quality UiO-66(Zr) submicronic particles, paving the way for their use within the nanotechnology domain, in addition to higher reaction yields, which makes this synthesis route suitable for the preparation of UiO-66(Zr) at a larger scale. In a final step, UiO-66(Zr) was prepared using conventional reflux conditions at the 0.5 kg scale, leading to a rather high space-time yield of 490 kg m(-3) day(-1), while keeping physicochemical properties similar to those obtained from smaller scale solvothermally prepared batches. PMID:24527942

Ragon, Florence; Horcajada, Patricia; Chevreau, Hubert; Hwang, Young Kyu; Lee, U-Hwang; Miller, Stuart R; Devic, Thomas; Chang, Jong-San; Serre, Christian

2014-03-01

51

Study on biodegradability of terephthalic acid in polyester fabric alkali-peeling process wastewater.  

Science.gov (United States)

Terephthalic acid (TA) and ethylene glycol (EG) are the main pollutants in polyester fabric alkali-peeling process wastewater (PAP-wastewater). The biodegradability of TA is crucial to the deep treatment of PAP-wastewater. Batch and continuous experiments were adopted to study the biodegradation of TA in synthetic wastewater. In anoxic batch experiments TA began to degrade gradually after EG was depleted completely. However, in aerobic batch experiments the biodegradation curves of TA in the presence of EG were almost identical to those of TA in the absence of EG. The combined process of anoxic hydrolysis-acidification bioreactor (HABR) and aerobic hybrid membrane bioreactor (HMBR) was employed to treat synthetic PAP-wastewater in continuous experiments. When TA was fed as sole substrate, about 6.1% was removed in the anoxic HABR and 92.1% was biodegraded in the aerobic HMBR. When TA and EG were fed as substrate, only 1.9% of TA was biodegraded in the anoxic HABR and 96.6% of TA was removed in the aerobic HMBR. By contrast, most EG was removed in the anoxic HABR. The experimental results revealed that the combined process of anoxic HABR and aerobic HMBR was an attractive alternative for the treatment of PAP-wastewater and other similar wastewater. PMID:24473302

Yang, Qiyong; Wu, Zhongwei; Tao, Chunyuan

2014-01-01

52

Lewis acid/base character and crystallisation properties of poly(butylene terephthalate).  

Science.gov (United States)

Two grades of poly(butylene terephthalate) were analysed by means of inverse gas chromatography (IGC) and the results correlated with the respective crystallisation properties. The following parameters were determined by IGC: the dispersive component of the surface tension, the enthalpy and the entropy of adsorption of selected polar and apolar probes, and the Lewis acidity and basicity constants, Ka and Kb respectively. The interpretation of the values determined for Ka and Kb is in agreement with the FTIR spectra relating to the carboxyl end-group and the hydroxyl end-group concentrations in these polymers. The differences in the molecular weight values and in the end-group type and concentration, between the two grades of PBT, do not cause differences in the crystallisation activation energy. This observation suggests that there is a leading contribution of the Lewis basic sites to the crystallisation activation energy of the grades of PBT that were analysed. However, the lower value of Ka and the greater molar mass of one of the PBT grades lead to a corresponding lower crystallisation degree. PMID:25576040

Santos, José M R C A; Guthrie, James T

2015-01-30

53

Influences of organic loading disturbances on the performance of anaerobic filter process to treat purified terephthalic acid wastewater.  

Science.gov (United States)

A lab-scale anaerobic filter process was operated for the treatment of purified terephthalic acid (PTA) wastewater, and the influences of organic loading disturbances on the process performance were investigated. After about 15 month operation, the COD removal efficiency was maintained at 79% under the volumetric loading rate of 5.05 kg-COD/m3/d and the hydraulic retention time (HRT) of 50 h. Interestingly, this performance could be further enhanced over 85% by applying a step-increase/decrease of the HRT, which was mainly due to the increased p-toluate degradation. In the shock loading tests of four major pollutants (benzoate, acetate, terephthalate and p-toluate), it was found that the overall process performance was adversely affected by all the shock loadings, indicating that the syntrophic microbial consortium involved in the PTA wastewater treatment is highly sensitive to the organic loading disturbances. The complex inhibition effects of the benzoate and acetate on the terephthalate and p-toluate degradations were mainly responsible for this sensitivity. PMID:19128962

Joung, Jea Youl; Lee, Hae Woo; Choi, Hyeoksun; Lee, Min Woo; Park, Jong Moon

2009-04-01

54

Pembuatan Kristal Polyethylene Terephthalate Dengan Reaksi Esterifikasi Langsung Terephthalate Acid Dan Ethylene Glycol Dengan Kapasitas Produksi 175.000 Ton/Tahun  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Pembuatan polyethylene terephthalate secara umum dikenal dengan menggunakan proses esterifikasi langsung. Pabrik polyethylene terephthalate ini direncanakan akan berproduksi dengan kapasitas 175.000 ton/tahun dan beroperasi selama 330 hari dalam setahun. Pabrik ini diharapkan dapat mengurangi ketergantungan Indonesia terhadap produk impor. Lokasi pabrik direncanakan di daerah Karawang, Jawa Barat dengan luas areal 27.738 m2, tenaga kerja yang dibutuhkan berjumlah 167 orang dengan bentuk ba...

Leman Sihotang

2009-01-01

55

Pembuatan Kristal Polyethylene Terephthalate Dengan Reaksi Esterifikasi Langsung Terephthalate Acid Dan Ethylene Glycol Dengan Kapasitas Produksi 200.000 Ton/Tahun  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Pembuatan polyethylene terephthalate secara umum dikenal dengan menggunakan proses esterifikasi langsung. Pabrik polyethylene terephthalate ini direncanakan akan berproduksi dengan kapasitas 200.000 ton/tahun dan beroperasi selama 330 hari dalam setahun. Pabrik ini diharapkan dapat mengurangi ketergantungan Indonesia terhadap produk impor. Lokasi pabrik direncanakan di daerah Karawang, Jawa Barat dengan luas areal 27.738 m2, tenaga kerja yang dibutuhkan berjumlah 167 orang dengan bentuk ba...

Edi Sinaga

2009-01-01

56

Analysis of impurities in crude and highly-purified terephthalic acid by capillary electrophoresis  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Neste trabalho, foi desenvolvido um método simples e rápido, utilizando eletroforese capilar (CE), para a análise simultânea de 4-carboxibenzaldeído (4-CBA), ácido p-toluóico (pTOL) e ácido benzóico (BZ), em lotes industriais de ácido tereftálico cru (CTA) e purificado (PTA). As condições eletroforé [...] ticas de análise foram: tampão tetraborato a 20 mmol L-1 (pH 9), injeção hidrodinâmica (5 s, 17 kPa), tensão aplicada de +30 kV e detecção direta em 200 nm. Foram analisados cinco lotes de CTA e quatro lotes de PTA nos teores de 4-CBA e pTOL pela metodologia proposta e as metodologias utilizadas na empresa Tereftalatos Mexicanos S.A. (TEMEX), que são cromatografia gasosa para pTOL e polarografia para 4-CBA, mostrando concordância entre os valores encontrados. Os níveis de BZ foram determinados apenas pela metodologia CE, apresentando no CTA, valores compreendidos entre 60 e 300 ppm, enquanto que no PTA, 5 a 7 ppm. Várias impurezas derivadas da oxidação incompleta do p-xileno foram investigadas, constatando-se a presença do ácido 4-hidroximetilbenzóico por comparação com padrões. Abstract in english In this work, a simple and fast capillary electrophoresis method for the simultaneous analysis of 4-carboxybenzaldehyde (4-CBA), p-toluic acid (pTOL) and benzoic acid (BZ) in industrial batches of crude (CTA) and highly-purified (PTA) terephthalic acid was developed. The electrophoretic conditions c [...] omprise: 20 mmol L-1 tetraborate buffer at pH 9, hydrodynamic injection (5 s/17 kPa), applied voltage of +30 kV and direct UV detection at 200 nm. The concentrations of 4-CBA and pTOL in five batches of CTA and four batches of PTA as determined by the proposed CE methodology were in agreement with the results from gas chromatography and polarography methods in current use in Tereftalatos Mexicanos S.A. (TEMEX). Levels of BZ were determined only by the CE methodology and ranged from 60 - 300 ppm in CTA and 5 - 7 ppm in PTA. Several impurities deriving from the incomplete oxidation of p-xylene were investigated. So far the positive identification of 4-hydroxymethylbenzoic acid was accomplished by comparison with pure standards.

Maria de Lourdes L., Moraes; Joel C., Rubim; Rene R., Realpozo; Marina F. M., Tavares.

2004-06-01

57

Biohydrogen production from purified terephthalic acid (PTA) processing wastewater by anaerobic fermentation using mixed microbial communities  

Energy Technology Data Exchange (ETDEWEB)

Purified terephthalic acid (PTA) processing wastewater was evaluated as a fermentable substrate for hydrogen (H{sub 2}) production with simultaneous wastewater treatment by dark-fermentation process in a continuous stirred-tank reactor (CSTR) with selectively enriched acidogenic mixed consortia under continuous flow condition in this paper. The inoculated sludge used in the reactor was excess sludge taken from a second settling tank in a local wastewater treatment plant. Under the conditions of the inoculants not less than 6.3 gVSS/L, the organic loading rate (OLR) of 16 kgCOD/m{sup 3} d, hydraulic retention time (HRT) of 6 h and temperature of (35 {+-} 1) C, when the pH value, alkalinity and oxidation-reduction potential (ORP) of the effluent ranged from 4.2 to 4.4, 280 to 350 mg CaCO{sub 3}/L, and -220 to -250 mV respectively, soluble metabolites were predominated by acetate and ethanol, with smaller quantities of propionate, butyrate and valerate. Stable ethanol-type fermentation was formed with the sum of ethanol and acetate concentration ratio of 70.31% to the total liquid products after 25 days operation. The H{sub 2} volume content was estimated to be 48-53% of the total biogas and the biogas was free of methane throughout the study. The average biomass concentration was estimated to be 10.82 gVSS/L, which favored H{sub 2} production efficiently. The rate of chemical oxygen demand (COD) removal reached at about 45% and a specific H{sub 2} production rate achieved 0.073 L/gMLVSS d in the study. This CSTR system showed a promising high-efficient bioprocess for H{sub 2} production from high-strength chemical wastewater. (author)

Zhu, Ge-Fu; Wu, Peng; Wei, Qun-Shan; Lin, Jian-yi; Liu, Hai-Ning [Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Gao, Yan-Li [China University of Geosciences, Wuhan 430074 (China)

2010-08-15

58

A new strategy for preparation of terephthalic acid by oxidation of p-xylene in aqueous medium  

Energy Technology Data Exchange (ETDEWEB)

Terephthalic acid (TPA) is an important bulk chemical for fibre industry. Commercially, most of TPA is produced by the homogenous liquid-phase oxidation of p-Xylene (pX) with air or O{sub 2} in acetic acid (HAC) in the temperature range of 180-250 C and 25-35 bar in presence of cobalt acetate and manganese acetate catalyst with bromide promoters. In the quest for an ecofriendly, safe and cost effective process to produce TPA a new strategy for the preparation of TPA by oxidation of pX in liquid phase through a two step process is explored. The first step involves the aerobic oxidation of pX in aqueous medium in the presence of Cobalt based homogeneous catalyst. Effects of various reaction parameters like pressure, temperature, catalyst, concentration etc. have been studied. The product composition could be varied with respect to p-toluic acid (p-TA), TPA and 4-carboxy benzaldehyde (4-CBA) by adjusting the operating conditions. Incorporation of co-catalysts like Mn, Ce affects the composition of reaction products. Oxidation of pX at 130 C yielded a product consisting of p-TA 81%, TPA-16%, 4-CBA 3%, at 80% conversion of pX. The reaction product obtained in the first step was further oxidized at 130-150 C in acetic acid medium in the presence of Co based catalyst to give TPA as a major product. Typical product composition ex-oxidation reactor was Terephthalic acid (86%) with p-Toluic acid (12%) and 4-CBA (2%). (orig.)

Saxena, M.P.; Sharma, S.K.; Gupta, A.K.; Kumar, K.; Bangwal, D.P. [Indian Inst. of Petroleum, Dehradun (India)

2005-07-01

59

Total synthesis of (+/-)-pentacycloanammoxic acid.  

Science.gov (United States)

The first total synthesis of (+/-)-pentacycloanammoxic acid/methyl ester (1), an unusual naturally occurring fatty acid from Candidatus Brocadia anammoxidans, has been accomplished by the sequence of reactions shown in Scheme 1. The C20-structure of 1 was assembled with stereocontrol from three building blocks: cyclooctatetraene, 2-cyclopentenone, and 7-bromoheptanoic acid. The synthesis of 1 confirms the proposed structure of 1. The mode of biosynthesis and absolute configuration have yet to be clarified. PMID:15571387

Mascitti, Vincent; Corey, E J

2004-12-01

60

Morphology, melting behavior, and non-isothermal crystallization of poly(butylene terephthalate)/poly(ethylene-co-methacrylic acid) blends  

Energy Technology Data Exchange (ETDEWEB)

The morphology, melting behavior, and non-isothermal crystallization of poly(butylene terephthalate) (PBT) and poly(ethylene-co-methacrylic acid) (PEMA) blends were studied with scanning electron microscopy, X-ray diffraction and differential scanning calorimetry (DSC). PEMA forms immiscible, yet compatible, blends with PBT. Subsequent DSC scans on melt-crystallized samples exhibited two melting endotherms (T{sub mI} and T{sub mII}). The presence of PEMA would facilitate the recrystallization during heating scan and retard PBT molecular chains to form a perfect crystal in cooling crystallization. The dispersion phases of molten PEMA acts as nucleating agents to enhance the crystallization rate of PBT. The solidified PBT could act as nucleating agents to enhance the crystallization of PEMA, but also retard the molecular mobility to reduce crystallization rate. The U* and K{sub g} of Hoffman-Lauritzen theory were also determined by Vyazovkin's methods to support the interpretation.

Huang, J.-W. [Department of Styling and Cosmetology, Tainan University of Technology, 529 Chung Cheng Rd., Yung Kang City 710, Taiwan (China)], E-mail: jw.huang@msa.hinet.net; Wen, Y.-L. [Department of Nursing, Meiho Institute of Technology, 23 Ping Kuang Rd., Neipu Hsiang, Pingtung 912, Taiwan (China); Department of Resources Engineering, National Cheng Kung University, No. 1, University Rd., Tainan City 701, Taiwan (China); Kang, C.-C. [R and D Center, Hi-End Polymer Film Co., Ltd. 15-1 Sin Jhong Rd., Sin Ying City 730, Taiwan (China); Yeh, M.-Y. [Department of Chemistry, National Cheng Kung University, No. 1, University Rd., Tainan City 701, Taiwan (China); Sustainable Environment Research Centre, National Cheng Kung University, Taiwan (China); Wen, S.-B. [Department of Nursing, Meiho Institute of Technology, 23 Ping Kuang Rd., Neipu Hsiang, Pingtung 912, Taiwan (China); Department of Resources Engineering, National Cheng Kung University, No. 1, University Rd., Tainan City 701, Taiwan (China)

2007-12-15

 
 
 
 
61

Morphology, melting behavior, and non-isothermal crystallization of poly(butylene terephthalate)/poly(ethylene-co-methacrylic acid) blends  

International Nuclear Information System (INIS)

The morphology, melting behavior, and non-isothermal crystallization of poly(butylene terephthalate) (PBT) and poly(ethylene-co-methacrylic acid) (PEMA) blends were studied with scanning electron microscopy, X-ray diffraction and differential scanning calorimetry (DSC). PEMA forms immiscible, yet compatible, blends with PBT. Subsequent DSC scans on melt-crystallized samples exhibited two melting endotherms (TmI and TmII). The presence of PEMA would facilitate the recrystallization during heating scan and retard PBT molecular chains to form a perfect crystal in cooling crystallization. The dispersion phases of molten PEMA acts as nucleating agents to enhance the crystallization rate of PBT. The solidified PBT could act as nucleating agents to enhance the crystallization of PEMA, but also retard the molecular mobility to reduce crystallization rate. The U* and Kg of Hoffman-Lauritzen theory were also determined by Vyazovkin's methods to support the interpretation

62

Bile acids: regulation of synthesis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Bile acids are physiological detergents that generate bile flow and facilitate intestinal absorption and transport of lipids, nutrients, and vitamins. Bile acids also are signaling molecules and inflammatory agents that rapidly activate nuclear receptors and cell signaling pathways that regulate lipid, glucose, and energy metabolism. The enterohepatic circulation of bile acids exerts important physiological functions not only in feedback inhibition of bile acid synthesis but also in control o...

Chiang, John Y. L.

2009-01-01

63

Polyesters production from the mixture of phthalic acid, terephthalic and glycerol; Producao de poliesteres a partir da mistura de acido ftalico, tereftalico e glicerol  

Energy Technology Data Exchange (ETDEWEB)

Glycerin, a byproduct of biodiesel is currently an environmental and economic problem for producers of this renewable fuel in Brazil and in others parts of the world. In order to offer new proposals for recovery, it is used for the manufacture of polyesters used in applications in diverse areas such as construction and automobile industry. This work reports the production of polymer from the mixture of terephthalic and phthalic acid in three different proportions. The polyesters showed good thermal stability, analyzed by TGA and DSC, with an increase proportional to the terephthalic acid content. The X-ray diffraction patterns show that the samples are semi crystalline polymers. The micrographs indicated the presence of a smoother surface in the polyester that has a larger amount of phthalic acid, as reported in the literature. Therefore, the materials showed good thermal properties and morphological characteristics, so it consists in a new alternative to use glycerin. (author)

Carvalho, A.L.S.; Oliveira, J.C.; Miranda, C.S.; Boaventura, J.S.; Jose, N.M., E-mail: adrianaequfba@gmail.co [Universidade Federal da Bahia (GECIM/UFBA), Salvador, BA (Brazil). Inst. de Quimica. Grupo de Energia e Ciencias dos Materiais; Carvalho, R.F. [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil). Escola Politecnica. Curso de Mestrado em Engenharia Ambiental Urbana

2010-07-01

64

In situ synthesis of TiO2/polyethylene terephthalate hybrid nanocomposites at low temperature  

Science.gov (United States)

TiO2 nanoflowers were in situ grown on polyethylene terephthalate (PET) non-woven fabric by hydrolysis of TiCl4 in aqueous solution in the presence of nanocrystal cellulose grafted PET fabric (NCC-g-PET) at a low temperature of 70 °C. Nanocrystal cellulose (NCC) pre-grafted on PET fabric acted as hydrophilic substrate and morphology inducing agent to promote the nucleation and crystal growth of TiO2. Detailed information on the synthetic process was presented. The resulting samples were characterized using FE-SEM, EDS, ATR-IR, Raman microscopy, XRD and TG analysis. The photocatalytic activity of the samples was evaluated by the degradation of orange methyl under solar light. Characteristic results indicate that rutile TiO2 nanoflowers have grown abundantly on PET non-woven fabric, and the established hydrogen bonding strengthens the interfacial interaction between the inorganic particles and the polymeric substrates. The methyl orange decoloration test under natural solar light demonstrates that this TiO2/PET hybrid nanocomposites exhibit excellent self-cleaning performance which is expected to have a good potential for commercialization.

Peng, Xinyan; Ding, Enyong; Xue, Feng

2012-06-01

65

In situ synthesis of TiO2/polyethylene terephthalate hybrid nanocomposites at low temperature  

International Nuclear Information System (INIS)

TiO2 nanoflowers were in situ grown on polyethylene terephthalate (PET) non-woven fabric by hydrolysis of TiCl4 in aqueous solution in the presence of nanocrystal cellulose grafted PET fabric (NCC-g-PET) at a low temperature of 70 °C. Nanocrystal cellulose (NCC) pre-grafted on PET fabric acted as hydrophilic substrate and morphology inducing agent to promote the nucleation and crystal growth of TiO2. Detailed information on the synthetic process was presented. The resulting samples were characterized using FE-SEM, EDS, ATR-IR, Raman microscopy, XRD and TG analysis. The photocatalytic activity of the samples was evaluated by the degradation of orange methyl under solar light. Characteristic results indicate that rutile TiO2 nanoflowers have grown abundantly on PET non-woven fabric, and the established hydrogen bonding strengthens the interfacial interaction between the inorganic particles and the polymeric substrates. The methyl orange decoloration test under natural solar light demonstrates that this TiO2/PET hybrid nanocomposites exhibit excellent self-cleaning performance which is expected to have a good potential for commercialization.

66

Atmospheric pressure synthesis of photoluminescent hybrid materials by sequential organometallic vapor infiltration into polyethylene terephthalate fibers  

Science.gov (United States)

Exposing a polymer to sequential organometallic vapor infiltration (SVI) under low pressure conditions can significantly modify the polymer's chemical, mechanical, and optical properties. We demonstrate that SVI of trimethylaluminum into polyethylene terephthalate (PET) can also proceed readily at atmospheric pressure, and at 60 °C the extent of reaction determined by mass uptake is independent of pressure between 2.5 Torr and 760 Torr. At 120 °C, however, the mass gain is 50% larger at 2.5 Torr relative to that at 760 Torr, indicating that the precursor diffusion in the chamber and fiber matrix decreases at higher source pressure. Mass gain decreases, in general, as the SVI process temperature increases both at 2.5 Torr and 760 Torr attributed to the faster reaction kinetics forming a barrier layer, which prevents further diffusion of the reactive species. The resulting PET/Al-Ox product shows high photoluminescence compared to untreated fibers. A physical mask on the polymer during infiltration at 760 Torr is replicated in the underlying polymer, producing an image in the polymer that is visible under UV illumination. Because of the reduced precursor diffusivity during exposure at 760 Torr, the image shows improved resolution compared to SVI performed under typical 2.5 Torr conditions.

Akyildiz, Halil I.; Mousa, Moataz Bellah M.; Jur, Jesse S.

2015-01-01

67

Assessing human exposure to phthalic acid and phthalate esters from mineral water stored in polyethylene terephthalate and glass bottles.  

Science.gov (United States)

Phthalic acid and phthalate esters are of growing interest due to their significant usage and potential toxicity. Polyethylene terephthalate (PET) and glass are both widely used materials for bottled drinking water. In this study, phthalic acid (PhA), bis(2-ethylhexyl) phthalate (DEHP), dimethyl phthalate (DMP), diethyl phthalate (DEP), diisobutyl phthalate (DiisoBP) and dibutyl phthalate (DBP) were analysed in a large number of Italian bottled water samples. These samples showed different concentrations of phthalates are nearly 20 times higher in samples bottled in PET than those from glass bottles with total levels of phthalates of 3.52 and 0.19 microg l(-1), respectively. However, the observed levels do not represent a significant exposure pathway when considering the US Environmental Protection Agency (USEPA) reference dose (an estimate of a daily oral exposure to the human population, including sensitive subgroups, that is likely to be without an appreciable risk of deleterious effects during a lifetime). In addition, no significant correlation was found between the phthalate concentrations and the physicochemical properties of the different water samples, apart from the still/sparkling water parameter for the PET samples. In this instance, slightly higher concentrations were observed for the PET bottled still water samples than for the sparkling water samples, although no explanation has been found yet. PMID:18348049

Montuori, P; Jover, E; Morgantini, M; Bayona, J M; Triassi, M

2008-04-01

68

Development of a bioprocess to convert PET derived terephthalic acid and biodiesel derived glycerol to medium chain length polyhydroxyalkanoate  

Energy Technology Data Exchange (ETDEWEB)

Sodium terephthalate (TA) produced from a PET pyrolysis product and waste glycerol (WG) from biodiesel manufacture were supplied to Pseudomonas putida GO16 in a fed-batch bioreactor. Six feeding strategies were employed by altering the sequence of TA and WG feeding. P. putida GO16 reached 8.70 g/l cell dry weight (CDW) and 2.61 g/l PHA in 48 h when grown on TA alone. When TA and WG were supplied in combination, biomass productivity (g/l/h) was increased between 1.3- and 1.7-fold and PHA productivity (g/l/h) was increased 1.8- to 2.2-fold compared to TA supplied alone. The monomer composition of the PHA accumulated from TA or WG was predominantly composed of 3-hydroxydecanoic acid. PHA monomers 3-hydroxytetradeeanoic acid and 3-hydroxytetradecenoic acid were not present in PHA accumulated from TA alone but were present when WG was supplied to the fermentation. When WG was either the sole carbon source or the predominant carbon source supplied to the fermentation the molecular weight of PHA accumulated was lower compared to PHA accumulated when TA was supplied as the sole substrate. Despite similarities in data for the properties of the polymers, PHAs produced with WG present in the PHA accumulation phase were tacky while PHA produced where TA was the sole carbon substrate in the polymer accumulation phase exhibited little or no tackiness at room temperature. The co-feeding of WG to fermentations allows for increased utilisation of TA. The order of feeding of WG and TA has an effect on TA utilisation and polymer properties. (orig.)

Kenny, Shane T.; Nikodinovic Runic, Jasmina; O' Connor, Kevin E. [University College Dublin (Ireland). School of Biomolecular and Biomedical Sciences; Kaminsky, Walter [Hamburg Univ. (Germany). Inst. of Technical and Macromolecular Chemistry; Woods, Trevor; Babu, Ramesh P. [Dublin Univ. (Ireland). Materials Ireland Polymer Research Center

2012-08-15

69

Inhibitors of Fatty Acid Synthesis and Elongation  

Science.gov (United States)

Fatty acid synthesis and fatty acid elongation are two parts of a critically important pathway in plants. The endproducts are essential components of cell membranes, waxes, and suberin. Two chemical families of herbicide (groups that share similar chemical structures) inhibit fatty acid synthesis, while fatty acid elongation is inhibited by two other families. This lesson will provide an overview of fatty acid synthesis and elongation, and explain where herbicides inhibit the pathway. Mechanisms of resistance to these herbicides will be described.

70

Dibutylphosphoric acid synthesis  

International Nuclear Information System (INIS)

This work consists on the synthesis of dibutylphosphoric acis (DBP) by reaction of butanol with phosphorus pentoxid and on its separation by liquid-liquid extraction. It also deals with the characterization of DBP by some physicochemical analysis methods such as : chromatography, pH-metry and infrared and ultraviolet spectrophotometries. this study showed essentialy, that DBP can be formed in an appreciable amount (55%) when the reaction is realised with butanol/pentoxid molar ratio upper than 3 at temperature of 95 C

71

Session 6: Purification of off-gases from terephthalic acid plants by new precious and base metal catalysts  

Energy Technology Data Exchange (ETDEWEB)

Catalysts have become essential to clean up the off-gases from automobiles as well as industrial plants. Large volumes of contaminated gas are generated during the production of terephthalic acid, an important raw material e.g. for the manufacture of PET. The emission streams from purified terephthalic acid (PTA) plants commonly contain carbon monoxide, methyl bromide (originating from the homogeneous catalyst system), and various volatile organic compounds (VOCs). Before the vent gas is exhausted to the atmosphere, these contaminants (often regulated) must be converted by catalytic oxidation. Due to the presence of bromide and sometimes high amounts of water special catalysts are required. Especially bromide suppresses catalytic activity by blocking sites. Furthermore, poly-bromo-benzenes (PBBs) can form due to interaction of released bromide with benzene in the feed stream. These PBBs are difficult to convert and can cause plugging or blockage in process lines. Currently, most commercially available catalysts are used at an inlet temperature higher than 350 C. The improvement of the catalyst activity is desired to increase the catalyst life-time by using lower temperatures or to be able to use lower catalyst volumes. Degussa has developed several catalyst solutions for this problem. Bead and monolithic catalysts were prepared and tested. With precious metal catalysts Pt shows the highest activity and resistance against bromide. The activity can be further boosted using an optimised wash-coat with oxygen storage components. The formation of poly-bromo-benzenes is associated with the relative position of the conversion curves of methyl bromide and benzene. Such by-products can be avoided if the benzene conversion is shifted to lower temperatures. This can be achieved by using acidic dopants, which both affect benzene and methyl bromide conversion. The behaviour of the catalyst can be controlled by varying the amount of the dopant. As some plants tolerate only rather low pressure drops, a catalyst with a lower cell density was tested. Significant improvement in pressure drop is achieved with only minor losses in conversion. Base metal catalysts may pose an economically interesting alternative to those based on precious metal. Both bead and monolithic type catalysts were prepared and tested against platinum catalysts. At moderate space velocities they show a comparable or sometimes even better performance. Only at high space velocities precious metal catalysts show a significant advantage. Ageing tests were performed using both precious metal and base metal catalysts at severe conditions. After more than 4000 hours on stream the performance was still stable for all catalysts tested. Based on these results Degussa has developed HDC-25, a new monolithic platinum catalyst with significantly improved activity which can be used at space velocities {>=} 15000 h{sup -1}. Excellent base metal catalysts by Degussa in bead or monolithic shape are a good choice for moderate space velocities. Some catalysts show an interesting behaviour at very high space velocities in the high temperature region of the conversion curve of benzene (see figure). While 100% conversion can be reached at lower temperatures, the conversion curve suddenly drops and finally comes up again. The effect is associated with the presence of methyl bromide in the feed gas. A thermal activation of the Deacon equilibrium could account for it. According to this equilibrium the formation of elemental bromine by oxidation of hydrogen bromide is favoured throughout the whole temperature range, so that at some temperature a shift from kinetically favoured hydrogen bromide to bromine as a more potent poison does proceed. At very high temperatures bromine desorbs from the catalyst surface. (authors)

Geisselmann, A.; Baoshu, Chen; Hausmann, R.; Viandt, M.; Panster, P.; Renneke, R.; Reisinger, M.; Stochniol, G. [Degussa AG, Hanau (Germany)

2004-07-01

72

Synthesis of aminoaldonic acids  

DEFF Research Database (Denmark)

With the aim of synthesising aminoaldonic acids, two 2-acetamido-2-deoxyaldonolactones with D-galacto (6) and D-arabino (11) configuration were prepared from acetylated sugar formazans in analogy with a known procedure. Empolying the same procedure to acetylated sugar phenylhydrazones gave mixtures of 2,5-anhydrides and not the expected 2-acetamido-2-deoxy aldose phenylhydrazones. The acetylated phenylhydrazones were found to eliminate acetic acid when heated in aqueous ethanol and 1-phenylazoalkenes could be isolated by crystallisation. By this method the 17, 20, 23 and 25 were prepared from the phenylhydrazones of D-galactose, D-mannose, L-rhamnose and D-arabinose, respectively. The phenylazoalkenes were selectively reduced with sodium borohydride to give 2-deoxy aldose phenylhydrazones, which were hydrolysed to the corresponding 2-deoxy aldoses. Thus, 2-deoxy-D-lyxo-hexose (33), 2-deoxy-D-arabino-hexose (35), 2,6-dideoxy-L-arabino-hexose (37) and 2-deoxy-D-erythro-hexose (39) were prepared by this new method.Three new 2,3-aziridino-2,3-dideoxyhexonamides 43, 51 and 64 were prepared by a three step procedure from the readily available D-glucono-1,5-lactone, D-gulono-1,4-lactone and L-rhamnono-1,4-lactone, respectively. A 2,3-aziridino-2,3-dideoxypentonamide 70 was also prepared from D-glucono-1,5-lactone. The lactones were converted into methyl 3,4-O-isopropylidene-2-O-sulfonyl esters 42, 50, 62 and 68, which upon treatment with concentrated aqueous ammonia yielded the aziridino compounds. The aziridino amides 43 and 51 were reductively cleaved with hydrazine to give 3-amino-2,3-dideoxyhexonhydrazides 83 and 85, which were easily converted into the corresponding lactone 84 and acid 86. The aziridine ring of 43 and 51 was also opened with acetic acid to give the 3-amino-3-deoxyhexonic acids 79 and 82, respectively. The aminolactone 84 was converted into the corresponding amino sugar 89.With the aim of synthesising substrates for the Pictet-Spengler reaction three 4-aldehydo acetamidodideoxytetronolactones 92, 97and 103 were prepared by periodate cleavage of the corresponding hexonolactones. These compounds did not react with 2-(3,4-dimethoxyphenyl)ethyl amine 105. Instead the commercially available unsubstituted 4-carboxyl tetronolactone 108 was converted into the 2-(3,4-dimethoxyphenyl)ethyl amides 110 and 111 in two steps. These amides were cyclised by the Bischler-Napieralski cyclisation to give the dihydroisoquinoline lactones 113 and 114, which were reduced to give the target tetrahydroisoquinoline lactones 115, 117 and 118.

JØrgensen, Christel Thea

1997-01-01

73

Total synthesis of (+/-)-martinellic acid.  

Science.gov (United States)

A 14-step synthesis of martinellic acid (1) that proceeds in 3% overall yield has been completed using the reaction of aniline 11 with Meldrum's acid-activated vinylcyclopropane 4 to give vinyl pyrrolidinone 12, condensation of aldehyde 13 with N-benzylglycine to form an azomethine ylide that cyclizes to give 14, selective reduction of 14 to amino alcohol 16 with LiBH(4) and MeOH, and guanidine formation by reaction of a cyanamide with 3-methyl-2-buten-1-amine in hexafluoro-2-propanol at 120 degrees C as key steps. [structure: see text] PMID:11784181

Snider, B B; Ahn, Y; O'Hare, S M

2001-12-27

74

Coexistence of one- and two-dimensional supramolecular assemblies of terephthalic acid on Pd(111) due to self-limiting deprotonation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The adsorption of terephthalic acid [C6H4(COOH)(2), TPA] on a Pd(111) surface has been investigated by means of scanning tunneling microscopy (STM), x-ray photoelectron spectroscopy, and near-edge x-ray absorption fine structure spectroscopy under ultrahigh vacuum conditions at room temperature. We find the coexistence of one- (1D) and two-dimensional (2D) molecular ordering. Our analysis indicates that the 1D phase consists of intact TPA chains stabilized by a dimerization of the self-comple...

Canas-ventura, M. E.; Klappenberger, F.; Clair, S.; Pons, S.; Kern, K.; Brune, H.; Strunskus, T.; Woll, C.; Fasel, R.; Barth, J. V.

2006-01-01

75

Chemical recycling of industrial poly(ethylene terephthalate) waste: synthesis of aromatic polyester polyols, their properties and use  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this study, the generation points, reasons and properties of industrial PET waste were examined in detail. Different chemical recycling ways were suggested for each kind of industrial PET waste. Under glycolysis of industrial PET waste by ethylene glycol, the yield of the main product bis(2-hidroxyethylene) terephthalate was higher than 85 %. Several series of aromatic polyester polyols (APP) were synthesized by transesterification of industrial PET waste using diethyleneglycol (DEG) in th...

Vitkauskiene?, Irena

2011-01-01

76

A metal-organic framework assembled from Y(III), Li(I), and terephthalate: hydrothermal synthesis, crystal structure, thermal decomposition and topological studies.  

Science.gov (United States)

A novel metal-organic framework assembled from Y(iii), Li(i), and terephthalate ligand, formulated as [LiY(BDC)2(H2O)·2(H2O)] (1) (H2BDC = terephthalic acid), has been obtained as single phase under hydrothermal conditions. The crystal structure was solved by single-crystal X-ray diffraction and the bulk was characterized by powder X-ray diffraction (PXRD), thermal analyses (TG-MS and DSC), vibrational spectroscopy (FTIR), scanning/transmission electron microscopy (SEM-EDX, TEM, SAED, and BF-STEM-EDX), and powder X-ray thermodiffractometry (HT-XRD). 1 crystallizes in monoclinic space group (P21/c, with a = 11.6415(7) Å, b = 16.0920(4) Å, c = 13.2243(8) Å and ? = 132.23(1)°) and possesses a 3D framework with 1D trigonal channels running along the [101] direction containing water molecules. The structure of 1 is made up of unusual four-membered rings formed by edge- and vertex-shared {YO8} and {LiO4} polyhedra. The four-membered rings are isolated and connected to each other via carboxylate groups. HT-XRD reveals that 1 undergoes phase transformation upon the dehydration process which is a reversible process involving a spontaneous rehydration characterized by fast kinetics. Topological studies were also performed revealing that 1 has a new 2-nodal net. PMID:24562753

Abdelbaky, Mohammed S M; Amghouz, Zakariae; García-Granda, Santiago; García, José R

2014-04-21

77

Fatty acid synthesis enzyme clans.  

Science.gov (United States)

Ketoacyl reductases (KRs), hydroxyacyl dehydratases (HDs), and enoyl reductases (ERs) are part of the fatty acid/polyketide synthesis cycle. They are known as acyl dehydrogenases, enoyl hydratases, and hydroxyacyl dehydrogenases, respectively, when catalyzing their reverse reactions. Earlier, we classified these enzymes into four KR, eight HD, and five ER families by statistical criteria. Members of all four KR families and three ER families have Rossmann folds, while five HD family members have HotDog folds. This suggests that those proteins with the same folds in different families may be distantly related, and therefore in clans, even though their amino acid sequences may not be homologous. We have now defined two clans containing three of the four KR families and two of the eight HD families, using manual and statistical tests. One of the ER families is related to the KR clan. PMID:25257602

Phan, Ngoc N; Lee, Yuen Keong; Reilly, Peter J

2014-09-26

78

Control of abscisic acid synthesis.  

Science.gov (United States)

The abscisic acid (ABA) biosynthetic pathway involves the formation of a 9-cis-epoxycarotenoid precursor. Oxidative cleavage then results in the formation of xanthoxin, which is subsequently converted to ABA. A number of steps in the pathway may control ABA synthesis, but particular attention has been given to the enzyme involved in the oxidative cleavage reaction, i.e. 9-cis-epoxycarotenoid dioxygenase (NCED). Cloning of a gene encoding this enzyme in maize was first reported in 1997. Mapping and DNA sequencing studies indicated that a wilty tomato mutant was due to a deletion in the gene encoding an enzyme with a very similar amino acid sequence to this maize NCED. The potential use of this gene in altering ABA content will be discussed together with other genes encoding ABA biosynthetic enzymes. PMID:11006307

Taylor, I B; Burbidge, A; Thompson, A J

2000-09-01

79

Morphology and thermal properties of electrospun fatty acids/polyethylene terephthalate composite fibers as novel form-stable phase change materials  

Energy Technology Data Exchange (ETDEWEB)

The ultrafine fibers based on the composites of polyethylene terephthalate (PET) and a series of fatty acids, lauric acid (LA), myristic acid (MA), palmitic acid (PA), and stearic acid (SA), were prepared successfully via electrospinning as form-stable phase change materials (PCMs). The morphology and thermal properties of the composite fibers were studied by field emission scanning electron microscopy (FE-SEM) and differential scanning calorimetry (DSC), respectively. It was found that the average fiber diameter increased generally with the content of fatty acid (LA) in the LA/PET composite fibers. The fibers with the low mass ratio maintained cylindrical shape with smooth surface while the quality became worse when the mass ratio is too high (more than 100/100). Moreover, the latent heat of the composite fibers increased with the increase of LA content and the phase transition temperature of the fibers have no obvious variations compared with LA. In contrast, both the latent heat and phase transition temperature of the fatty acid/PET composite fibers varied with the type of the fatty acids, and could be well maintained after 100 heating-cooling thermal cycles, which demonstrated that the composite fibers had good thermal stability and reliability. (author)

Chen, Changzhong [Key Laboratory of Cellulose and Lignocellulosics Chemistry, Guangzhou Institute of Chemistry, Chinese Academy of Sciences, Guangzhou 510650 (China); Graduate School of Chinese Academy of Sciences, Beijing 100049 (China); Wang, Linge [Key Laboratory of Cellulose and Lignocellulosics Chemistry, Guangzhou Institute of Chemistry, Chinese Academy of Sciences, Guangzhou 510650 (China); Department of Chemistry, University of Sheffield, Sheffield S3 7HF (United Kingdom); Huang, Yong [Key Laboratory of Cellulose and Lignocellulosics Chemistry, Guangzhou Institute of Chemistry, Chinese Academy of Sciences, Guangzhou 510650 (China); State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China)

2008-11-15

80

Coexistence of one- and two-dimensional supramolecular assemblies of terephthalic acid on Pd(111) due to self-limiting deprotonation.  

Science.gov (United States)

The adsorption of terephthalic acid [C(6)H(4)(COOH)(2), TPA] on a Pd(111) surface has been investigated by means of scanning tunneling microscopy (STM), x-ray photoelectron spectroscopy, and near-edge x-ray absorption fine structure spectroscopy under ultrahigh vacuum conditions at room temperature. We find the coexistence of one- (1D) and two-dimensional (2D) molecular ordering. Our analysis indicates that the 1D phase consists of intact TPA chains stabilized by a dimerization of the self-complementary carboxyl groups, whereas in the 2D phase, consisting of deprotonated entities, the molecules form lateral ionic hydrogen bonds. The supramolecular growth dynamics and the resulting structures are explained by a self-limiting deprotonation process mediated by the catalytic activity of the Pd surface. Our models for the molecular ordering are supported by molecular mechanics calculations and a simulation of high resolution STM images. PMID:17115782

Cañas-Ventura, M E; Klappenberger, F; Clair, S; Pons, S; Kern, K; Brune, H; Strunskus, T; Wöll, Ch; Fasel, R; Barth, J V

2006-11-14

 
 
 
 
81

Mechanical properties and morphology of biodegradable poly(lactic acid)/poly(butylene adipate-co-terephthalate) blends compatibilized by transesterification  

International Nuclear Information System (INIS)

Highlights: ? Compatibility between PLA and PBAT is improved through transesterification. ? Elongation at break of PLA was up to almost 300%. ? Both toughness and stiffness of PLA/PBAT blends are improved significantly after the incorporation of TBT. -- Abstract: Biodegradable poly(lactic acid) (PLA)/poly(butylene adipate-co-terephthalate) (PBAT) blends with various tetrabutyl titanate (TBT) concentration were prepared through melt-extrusion. Mechanical properties and morphology were characterized in terms of tensile and impact testing, dynamical mechanical analysis and scanning electron micrograph (SEM). The results indicated that the overall mechanical properties (including tensile strength, elongation at break, toughness and stiffness) of PLA/PBAT blends can be improved significantly after the incorporation of TBT. The SEM micrographs demonstrated that the compatibility and strong interaction between PLA and PBAT was improved via transesterification during melt-extrusion. The interfacial debonding, pullout of PBAT, yielding deformation were the most important mechanisms to improve toughness.

82

1,4-Bis(4,5-dihydro-1H-imidazol-2-ylbenzene–terephthalic acid–water (1/1/4  

Directory of Open Access Journals (Sweden)

Full Text Available The asymmetric unit of the title compound, C12H14N4·C8H6O4·4H2O, consists of one half of the 1,4-bis(4,5-dihydro-1H-imidazol-2-ylbenzene (bib molecule, one half of the terephthalic acid (TA molecule and two water molecules. Both the bib and the TA molecules reside on crystallographic inversion centers, which coincide with the centroids of the respective benzene rings. The bib and the TA, together with the water molecules, are linked through intermolecular O—H...O, O—H...N and N—H...O hydrogen bonds, forming a three-dimensional network of stacked layers. Weak intermolecular C—H...O contacts support the stability of the crystal structure.

Shao-Ming Shang

2009-11-01

83

Coexistence of one- and two-dimensional supramolecular assemblies of terephthalic acid on Pd(111) due to self-limiting deprotonation  

International Nuclear Information System (INIS)

The adsorption of terephthalic acid [C6H4(COOH)2, TPA] on a Pd(111) surface has been investigated by means of scanning tunneling microscopy (STM), x-ray photoelectron spectroscopy, and near-edge x-ray absorption fine structure spectroscopy under ultrahigh vacuum conditions at room temperature. We find the coexistence of one- (1D) and two-dimensional (2D) molecular ordering. Our analysis indicates that the 1D phase consists of intact TPA chains stabilized by a dimerization of the self-complementary carboxyl groups, whereas in the 2D phase, consisting of deprotonated entities, the molecules form lateral ionic hydrogen bonds. The supramolecular growth dynamics and the resulting structures are explained by a self-limiting deprotonation process mediated by the catalytic activity of the Pd surface. Our models for the molecular ordering are supported by molecular mechanics calculations and a simulation of high resolution STM images

84

Surface modification of poly(ethylene terephthalate) (PET) film by gamma-ray induced grafting of poly(acrylic acid) and its application in antibacterial hybrid film  

International Nuclear Information System (INIS)

Acrylic acid (AA) was facilely grafted onto poly(ethylene terephthalate) (PET) film through gamma-ray induced graft copolymerization. Silver nanoparticles produced by the chemical reduction of silver ions were then immobilized by carboxylic anions and embedded on the surface of PET-g-PAA film. It was found that the DG of PAA on PET film increases with the absorbed dose and would finally control the amount of loaded silver nanoparticles. The prepared PET-g-PAA/Ag hybrid films were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). The bactericidal activity of the PET-g-PAA/Ag hybrid film was evaluated by the efficiency of killing Escherichia coli. The results showed that the PET-g-PAA/Ag hybrid film has a strong and stable antibacterial activity.

85

Protein synthesis inhibitors and gastric acid secretion.  

Science.gov (United States)

The involvement of de novo protein synthesis in acid secretion by the in vitro bullfrog gastric mucosa was examined using the inhibitors cycloheximide and puromycin. Both inhibitors reduced [3H]leucine incorporation by more than 90%. The inhibition of protein synthesis had no influence on spontaneous acid secretion nor did it effect secretory stimulation by histamine, carbachol, pentagastrin, or theophylline. Oxygen consumption by nonstimulated and theophyllinestimulated tissues was shown to be independent of protein synthesis. The dramatic morphological changes observed in oxyntic cells during a transition from rest to active secretion persisted in cycloheximide-and puromycin-treated tissues. Stereological analysis of the apical membrane surface area density failed to demonstrate any quantitative influence of protein synthesis inhibition. These studies quantitatively confirm that protein synthesis is not required for the biochemical and morphological events involved in acid secretion by the in vitro frog gastric mucosa. PMID:305378

Carlisle, K S; Reagan, C R; Hersey, S J

1978-03-01

86

Regulation of ascorbic acid synthesis in plants  

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Ascorbic acid (AsA) is a major antioxidant and plays an important role in plant growth and development. There are two aspects to improve AsA content, including de novo synthesis and recycling from its oxidized form. However, the knowledge of regulatory mechanisms of AsA synthesis pathways and metabolism still remains limited. We have determined that AsA synthesis process was modulated on both transcriptional and post-transcriptional levels in Arabidopsis. GDP-mannose pyrophosphorylase (VTC1) ...

Wang, Juan; Zhang, Zhijin; Huang, Rongfeng

2013-01-01

87

Aldehyde-alcohol reactions catalyzed under mild conditions by chromium(III) terephthalate metal organic framework (MIL-101) and phosphotungstic acid composites.  

Science.gov (United States)

Porous materials based on chromium(III) terephthalate metal organic frameworks (MIL-101) and their composites with phosphotungstic acid (PTA) were studied as heterogeneous acid catalysts in aldehyde-alcohol reactions exemplified by acetaldehyde-phenol (A-P) condensation and dimethylacetal formation from benzaldehyde and methanol (B-M reaction). The MIL-101 was synthesized solvothermically in water, and the MIL101/PTA composite materials were obtained by either impregnation of the already prepared MIL-101 porous matrix with phosphotungstic acid solution or by solvothermic treatment of aqueous mixtures of Cr(NO(3))(3), and terephthalic and phosphotungstic acids. The MIL101/PTA materials appeared to be effective catalysts for both A-P and B-M reactions occurring at room temperature, with half-lives ranging from 0.5 h (A-P) to 1.5-2 h (B-M) and turnover numbers over 600 for A-P and over 2900 for the B-M reaction, respectively. A synergistic effect of the strong acidic moieties (PTA) addition to mildly acidic Brønsted and Lewis acid cites of the MIL-101 was observed with the MIL101/PTA composites. The ability of the PTA and MIL101/PTA materials to strongly absorb and condense acetaldehyde vapors was discovered, with the MIL101/PTA absorbing over 10-fold its dry weight of acetaldehyde condensate at room temperature. The acetaldehyde was converted rapidly to crotonaldehyde and higher-molecular-weight compounds while in contact with MIL-101 and MIL101/PTA materials. The stability of the MIL-101 and MIL101/PTA catalysts was assessed within four cycles of the 1-day alcohol-aldehyde reactions in terms of the overall catalyst recovery, PTA or Cr content, and reaction rate constants in each cycle. The loss of the catalyst over 4 cycles was approximately 10 wt % for all tested catalysts due to the incomplete recovery and minute dissolution of the components. The reaction rates in all cycles remained unchanged and the catalyst losses stopped after the third cycle. The developed MIL101/PTA composites appear to be feasible for industrial catalytic applications. PMID:22091761

Bromberg, Lev; Hatton, T Alan

2011-12-01

88

Tetramethylammonium hydrogen terephthalate  

Directory of Open Access Journals (Sweden)

Full Text Available The asymmetric unit of the title salt, C4H12N+·C8H5O4?, contains one half of a tetramethylammonium cation and one half of a hydrogen terephthalate monoanion. The N atom of the ammonium cation lies on a twofold rotation axis and the centre of mass of the terephthalate anion is on a centre of inversion. In the crystal, the centrosymmetric terephthalate ions are linked by a very short symmetric O—H...O hydrogen bond [O...O = 2.4610?(19?Å] into a one-dimensional polymeric chain along [1-12]. The tetramethylammonium cations and terephthalate anions are then connected through a pair of bifurcated acceptor C—H...O hydrogen bonds, generating a three-dimensional supramolecular network. The carboxylate groups at both ends of the terephthalate anion are charge-shared with an equal probability of 0.5.

Leila Dolatyari

2012-10-01

89

Exposure to the polyester PET precursor-terephthalic acid induces and perpetuates DNA damage-harboring non-malignant human breast cells.  

Science.gov (United States)

Identification of early perturbations induced in cells from non-cancerous breast tissue is critical for understanding possible breast cancer risk from chemical exposure. We have demonstrated previously that exposure to the ubiquitous xenoestrogens, bisphenol A (BPA) and methyl paraben, promotes the hallmarks of cancer in non-malignant human high-risk donor breast epithelial cells (HRBECs) isolated from several donors. Here we show that terephthalic acid (TPA), a major chemical precursor of polyethylene terephthalate (PET) containers used for the storage of food and beverages, increased the ER?: ER? ratio in multiple HRBEC samples, suggesting an estrogenic effect. Although, like BPA and methyl paraben, TPA also promoted resistance to tamoxifen-induced apoptosis, unlike these chemicals instead of inducing an increased S-phase fraction, TPA treatment arrested cell proliferation. DNA-PK, ATM and members of the MRN complex, known to be involved in DNA damage sensor and effector proteins, were elevated indicating induction of DNA strand breaks. Early DNA damage checkpoint response, mediated through p53/p21, led to G1 arrest in TPA-exposed cells. Removal of TPA from the growth medium resulted in the rapid induction of BCL2, increasing the ratio of anti-: pro-apoptotic proteins, together with overexpression of Cyclin A/CDK2 proteins. Consequently, despite elevated p53(pSer15) and H2AX(pSer139), indicating sustained DNA damage, TPA exposed cells resumed robust growth rates seen prior to TPA exposure. The propensity for the perpetuation of DNA aberrations that activate DNA damage pathways in non-malignant breast cells justifies careful consideration of human exposure to TPA, particularly at vulnerable life stages. PMID:25411358

Luciani-Torres, Maria Gloria; Moore, Dan H; Goodson, William H; Dairkee, Shanaz H

2015-01-01

90

Synthesis of a metal-organic framework material, iron terephthalate, by ultrasound, microwave, and conventional electric heating: a kinetic study.  

Science.gov (United States)

A metal-organic framework material named MIL-53(Fe), iron terephthalate, has been synthesized sovothermally at a relatively low temperature by not only conventional electric (CE) heating, but also by irradiation under ultrasound (US) and microwave (MW) conditions to gain an understanding of the accelerated syntheses induced by US and MW. The kinetics for nucleation and crystal growth were analyzed by measuring the crystallinity of MIL-53(Fe) under various conditions. The nucleation and crystal growth rates were estimated from crystallization curves of the change in crystallinity with reaction time. The activation energies and pre-exponential factors were calculated from Arrhenius plots. It was confirmed that the rate of crystallization (both nucleation and crystal growth) decreases in the order US>MW>CE, and that the accelerated syntheses under US and MW conditions are due to increased pre-exponential factors rather than decreased activation energies. It is suggested that physical effects such as hot spots are more important than chemical effects in the accelerated syntheses induced by US and MW irradiation. The syntheses were also conducted in two steps to understand quantitatively the acceleration induced by MW and it was found that the acceleration in crystal growth is more important than the acceleration in nucleation, even though both processes are accelerated by MW irradiation. PMID:20014080

Haque, Enamul; Khan, Nazmul Abedin; Park, Jung Hwa; Jhung, Sung Hwa

2010-01-18

91

Synthesis of derivatives of tetronic acid and pulvinic acid. Total synthesis of norbadione A  

International Nuclear Information System (INIS)

When vegetables like mushrooms are contaminated by radioactive caesium 137, this radioactive caesium is associated to norbadione A, a natural pigment present in two mushroom species and which can be used as a caesium decorporation agent or maybe as protection agent against ionizing radiations. Within this perspective, this research report describes the biosynthesis and the structure and properties of the norbadione A and of pulvinic acids (physicochemical properties, anti-oxidizing properties). Then, it presents the various tetronic acids (3-acyl-, 3-alkyl-, 3-alkoxy-, 3-aryl-tetronic acids and non 3-substituted tetronic acids), their synthesis path as they are described in the literature, and presents a new synthesis approach using a tandem reaction (with different esters or hydroxy esters) and the synthesis of tetronic acids. The author also proposes a new synthesis way for methyl pulvinates, and finally reports the work on the development of a total synthesis of the norbadione A

92

Synthesis and properties of reduced molybdogermanic acid  

International Nuclear Information System (INIS)

By the reduction of ?-molybdogermanic acid (?-MGA) by ascorbic acid in the presence of diethyl ether the reduced molybdogermanic acid (MGA) is obtained in a crystalline form. The data of spectroscopic and voltamperometric investigation of MGA show that in case of NGA synthesis by etheric method ?-isomer transforms into ?-isomer-product of 4-electrons addition. In case of chemical or electrochemical ?-MGA reduction in aqueous solutions isomerization does not occur

93

A new approach of synthesis and morphological control of poly(ethylene terephthalate)-g-polyacrylonitrile composite film with a porous surface  

Science.gov (United States)

Poly(ethylene terephthalate)-g-polyacrylonitrile (PET-g-PAN) composite film with a porous surface was fabricated via gamma-ray-radiation-induced graft polymerization on PET film in an aqueous solution system. The original PET film was first irradiated by gamma ray in the aqueous solution of acrylic acid. Next, the graft polymerization of acrylonitrile (AN) was induced by gamma ray on the surface of the above modified PET film in an aqueous solution of AN. The prepared PET-g-PAN composite film has a smaller static water contact angle than the original PET film. The SEM and AFM images show that the grafted PAN layer on the surface of PET-g-PAN composite film is composed of closely-arranged spherical PAN microspheres with an average diameter of 30 nm. The gaps between the PAN microspheres form fine pores (less than 30 nm) on the surface. The gas barrier property of the PET-g-PAN composite film is much better than that of the original PET film. This work provides a facile and green method to prepare PET-g-PAN composite film with a controllable porous surface morphology by taking advantage of the radiation-induced graft polymerization technique in an aqueous solution system.

Xu, Yongfei; Wang, Yunlong; Wang, Mozhen; Wu, Qichao; Zhou, Xiao; Ge, Xuewu

2015-01-01

94

The effect of layer-by-layer chitosan-hyaluronic acid coating on graft-to-bone healing of a poly(ethylene terephthalate) artificial ligament.  

Science.gov (United States)

Surface coating with an organic layer-by-layer self-assembled template of chitosan and hyaluronic acid on a poly(ethylene terephthalate) (PET) artificial ligament was designed for the promotion and enhancement of graft-to-bone healing after artificial ligament implantation in a bone tunnel. The results of in vitro culturing of MC3T3-E1 mouse osteoblastic cells supported the hypothesis that the layer-by-layer coating of chitosan and hyaluronic acid could promote the cell compatibility of grafts and could promote osteoblast proliferation. A rabbit extra-articular tendon-to-bone healing model was used to evaluate the effect of this kind of surface-modified stainless artificial ligament in vivo. The final results proved that this organic compound coating could significantly promote and enhance new bone formation at the graft-bone interface histologically and, correspondingly, the experimental group with coating had significantly higher biomechanical properties compared with controls at 8 weeks (P < 0.05). PMID:21255485

Li, Hong; Ge, Yunsheng; Zhang, Pengyun; Wu, Lingxiang; Chen, Shiyi

2012-01-01

95

Deregulation of the p16-cyclin D1/cyclin-dependent kinase 4-retinoblastoma pathway involved in the rat bladder carcinogenesis induced by terephthalic acid-calculi.  

Science.gov (United States)

Prolonged cell proliferation in response to irritation by calculi may itself evoke malignant transformation of the urothelium. However, the molecular mechanisms underlying this process are still unknown. The aim of the present study was to investigate cell cycle regulatory mechanisms in bladder carcinogenesis induced by bladder calculi. Six-week-old Wistar rats were consecutively fed a diet containing 5% terephthalic acid (TPA), 5% TPA plus 4% sodium bicarbonate (NaHCO(3)), 4% NaHCO(3), or basal diet for 48 weeks. Animals were killed at weeks 12, 24, and 48. Treatment with 5% TPA caused high incidences of bladder calculi, preneoplastic lesions, and neoplastic lesions. Immunohistochemical examination revealed overexpression of cyclin D1, cyclin-dependent kinase 4 (Cdk4), retinoblastoma (Rb), and proliferating cell nuclear antigen (PCNA) in bladder preneoplastic and neoplastic lesions. In contrast, p16 expression was reduced or absent. These results were confirmed by immunoblotting analysis. Quantitation of mRNA by real-time reverse transcription-polymerase chain reaction (RT-PCR) showed a significant increase in cyclin D1 and PCNA mRNA in tumor cells. None of the 16 transitional cell carcinomas (TCCs) had ras mutations as examined by PCR-single strand conformational polymorphism (PCR-SSCP) analysis. These results suggested that deregulation of p16-cyclin D1/Cdk4-Rb pathway, but not oncogenic activation of ras, plays a crucial role in bladder tumorigenesis induced by bladder calculi. PMID:16896691

Cui, Lunbiao; Shi, Yuan; Qian, Jie; Dai, Guidong; Wang, Yubang; Xia, Yankai; Chen, Jianfeng; Song, Ling; Wang, Shouling; Wang, Xinru

2006-10-01

96

Potential method for reducing emissions of polycyclic aromatic hydrocarbons from the incineration of biological sludge for the terephthalic acid manufacturing industry.  

Science.gov (United States)

This study illustrates a potential method for reducing PAH emissions from the incineration of biological sludge by adding a suitable and available waste as a co-fuel. The whole study was conducted on a full-scale fluidized-bed incinerator operated by a terephthalic acid (TPA) manufacturing plant for disposing of biological sludge. Two incinerating conditions were studied, one directly incinerating biological sludge (the normal incinerating condition), and the other adding the waste TPA as a co-fuel during the biological sludge incineration process (the trial incinerating condition). Both incinerating conditions used heavy oil as auxiliary fuel. Although the former had a higher heavy oil consumption rate than the latter, both had comparable combustion efficiencies. Results show that the total PAH input mass rate for the former was only 2.35 times higher than the latter, but the total PAH emission factor for the former was 6.52 times higher than the latter. Total PAH output/input mass ratios for both incinerating conditions were lower than unity, but the value for the normal incinerating condition was approximately 2.91 times higher than the trial condition. In conclusion, the use of waste TPA as a co-fuel not only saved the consumption of heavy oil but also reduced PAH emissions during the combustion process. PMID:12188374

Wang, Lin-Chi; Lee, Wen-Jhy; Tsai, Perng-Jy; Chen, Shui-Jen

2002-08-01

97

Synthesis of excitatory amino acid analogues  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A general route to excitatory amino acid analogues has been developed as exemplified by the synthesis of A-1 and A-2. The key reactions involved were a Negishi coupling of Jackson's organozinc reagent with vinyl bromide 8 and subsequent ring closure of 15 and 16 using the Mitsunobu reaction. © Georg Thieme Verlag Stuttgart.

Goundry, Wrf; Lee, V.; Baldwin, Je

2006-01-01

98

Preparation of polymer blends from glycerol, fumaric acid and of poly(ethylene terephthalate) (PET) recycled; Preparacao de blendas polimericas a partir do glicerol, acido fumarico e do politereftalato de etileno (PET) pos consumo  

Energy Technology Data Exchange (ETDEWEB)

Polymer blends based on recycled poly(ethylene terephthalate) (PET) and poly(glycerol fumarate) polyesters were prepared in different PET concentrations. The PET powder was dispersed during the poly(glycerol fumarate) synthesis at 260 deg C. The resulting blends were characterized by X-ray diffraction. The thermal stability of the materials was evaluated by thermogravimetric analysis and differential scanning calorimetry. The morphology was studies by scanning electron microscopy. The blends were clearly immiscible. The possibility of (interfacial) compatibilization of the PET domains, caused by transesterification reactions between PET and glycerol were discussed. (author)

Medeiros, Marina A.O.; Guimaraes, Danilo H.; Brioude, Michel M.; Jose, Nadia M. [Instituto de Quimica, Universidade Federal da Bahia, Salvador, BA (Brazil); Prado, Luis A.S. de A. [Institut fuer Kunststoffe und Verbundwerkstoffe - Technische Universitaet Hamburg-Harburg, Hamburg (Germany)

2011-07-01

99

Preparation, morphology and thermal properties of electrospun fatty acid eutectics/polyethylene terephthalate form-stable phase change ultrafine composite fibers for thermal energy storage  

International Nuclear Information System (INIS)

Highlights: ? Electrospun binary fatty acid eutectics/PET ultrafine composite fibers were prepared. ? Fatty acid eutectics had appropriate phase transition temperature and heat enthalpy. ? Their morphological structures and thermal properties were different from each other. ? Composite fibers could be innovative form-stable PCMs for thermal energy storage. - Abstract: The ultrafine composite fibers based on the composites of binary fatty acid eutectics and polyethylene terephthalate (PET) with varied fatty acid eutectics/PET mass ratios (50/100, 70/100, 100/100 and 120/100) were fabricated using the technique of electrospinning as form-stable phase change materials (PCMs). The five binary fatty acid eutectics including LA–MA, LA–PA, MA–PA, MA–SA and PA–SA were prepared according to Schrader equation, and then were selected as an innovative type of solid–liquid PCMs. The results characterized by differential scanning calorimeter (DSC) indicated that the prepared binary fatty acid eutectics with low phase transition temperatures and high heat enthalpies for climatic requirements were more suitable for applications in building energy storage. The structural morphologies, thermal energy storage and thermal stability properties of the ultrafine composite fibers were investigated by scanning electron microscope (SEM), DSC and thermogravimetric analysis (TGA), respectively. SEM images revealed that the electrospun binary fatty acid eutectics/PET ultrafineutectics/PET ultrafine composite fibers possessed the wrinkled surfaces morphologies compared with the neat PET fibers with cylindrical shape and smooth surfaces; the grooves or ridges on the corrugated surface of the ultrafine composite fibers became more and more prominent with increasing fatty acid eutectics amount in the composite fibers. The fibers with the low mass ratio maintained good structural morphologies while the quality became worse when the mass ratio is too high (more than 100/100). DSC measurements suggested that the heat enthalpies of melting and crystallization of the ultrafine composite fibers increased gradually with increasing fatty acid eutectics amounts, but their phase transition temperatures had almost no obvious variation as relative to the corresponding fatty acid eutectics. Meanwhile, the characteristic temperatures and heat enthalpies of the ultrafine composite fibers varied with the different types of binary fatty acid eutectics. TGA results indicated that the degradation of electrospun binary fatty acid eutectics/PET ultrafine composite fibers with representative mass ratio of 100/100 had two steps and corresponded respectively to the degradations of binary fatty acid eutectics and PET polymer chains; and the charred residue at 700 °C of the composite fibers was lower than that of the neat PET fibers. It could be envisioned that the electrospun binary fatty acid eutectics/PET composite fibers would be extensively used for latent heat storage in the field of building energy conservation.

100

Electronic [UV-Visible] and vibrational [FT-IR, FT-Raman] investigation and NMR-mass spectroscopic analysis of terephthalic acid using quantum Gaussian calculations.  

Science.gov (United States)

In this research work, the vibrational IR, polarization Raman, NMR and mass spectra of terephthalic acid (TA) were recorded. The observed fundamental peaks (IR, Raman) were assigned according to their distinctiveness region. The hybrid computational calculations were carried out for calculating geometrical and vibrational parameters by DFT (B3LYP and B3PW91) methods with 6-31++G(d,p) and 6-311++G(d,p) basis sets and the corresponding results were tabulated. The molecular mass spectral data related to base molecule and substitutional group of the compound was analyzed. The modification of the chemical property by the reaction mechanism of the injection of dicarboxylic group in the base molecule was investigated. The (13)C and (1)H NMR spectra were simulated by using the gauge independent atomic orbital (GIAO) method and the absolute chemical shifts related to TMS were compared with experimental spectra. The study on the electronic and optical properties; absorption wavelengths, excitation energy, dipole moment and frontier molecular orbital energies, were performed by hybrid Gaussian calculation methods. The orbital energies of different levels of HOMO and LUMO were calculated and the molecular orbital lobe overlapping showed the inter charge transformation between the base molecule and ligand group. From the frontier molecular orbitals (FMO), the possibility of electrophilic and nucleophilic hit also analyzed. The NLO activity of the title compound related to Polarizability and hyperpolarizability were also discussed. The present molecule was fragmented with respect to atomic mass and the mass variation depends on the substitutions have also been studied. PMID:25561302

Karthikeyan, N; Joseph Prince, J; Ramalingam, S; Periandy, S

2015-03-15

 
 
 
 
101

Anaerobic-aerobic treatment of purified terephthalic acid (PTA) effluent; a techno-economic alternative to two-stage aerobic process.  

Science.gov (United States)

This paper addresses the treatment of purified terephthalic acid (PTA) effluent using anaerobic and aerobic processes. Laboratory studies were carried out on flow proportionate composite wastewater generated from the manufacturing of PTA. An activated sludge process (ASP-two stage and single stage) and an upflow anaerobic fixed film fixed bed reactor (AFFFBR) were used, individually and in combination. The performance of a full-scale ETP under existing operating conditions was also studied. Full scale ETP studies revealed that the treatment of PTA effluent using a two-stage ASP alone does not meet treated effluent quality within the prescribed Indian Standards. The biomass produced in the two stage ASP was very viscous and fluffy and the sludge volume index (SVI) was very high (200-450 ml/g). However, pretreatment of PTA effluent using an upflow AFFFBR ensured substantial reduction in BOD (63%) and COD (62%) with recovery of biogas at 1.8-1.96 l/l effluent treated at a volumetric loading rate (VLR) 4-5 kg COD/m(3) d. The methane content in the biogas varied between 55% and 60%. The pretreated effluent from the upflow AFFFBR was then treated through a single stage ASP. The biomass produced in the ASP after anaerobic treatment had very good settlability (SVI: 75-90 ml/g) as compared to the two stage ASP and the treated effluent quality with respect to BOD, COD and SS was within the prescribed Indian Standards. The alternative treatment process comprising an upflow AFFFBR and a single stage ASP ensured net power saving of 257 kW and in addition generated 442 kW of power through the AFFFBR. PMID:17223249

Pophali, G R; Khan, R; Dhodapkar, R S; Nandy, T; Devotta, S

2007-12-01

102

Corrosion of an amorphous indium tin oxide film on polyethylene terephthalate at low concentrations of acrylic acid  

International Nuclear Information System (INIS)

Highlights: ? Corrosion of ITO film on polymer substrate. ? Removal of In from ITO in acrylic acid. ? Degradation of conductivity of ITO film with acrylic adhesives. - Abstract: The corrosion behavior of ITO film deposited at low temperature on a polymer substrate by DC magnetron sputtering is studied in 0.05 M acrylic acid to investigate possible corrosion in contact with acrylic adhesives, which are employed in the fabrication of flexible optoelectronic devices. The shift in steady state open circuit potential (OCP) to negative values in electrochemical measurements suggests the increase in dissolution of ITO film with increasing immersion time. The potentiodynamic polarization results show an increase in Ecorr and a decrease in Icorr to lower values with time. This suggests that the electro-activity of ITO film decreases with increasing immersion time. Scanning electron microscopy shows corrosion of the ITO film. X-ray photoelectron spectroscopy analysis indicates a gradual removal of indium from the ITO layer. Electrochemical impedance spectroscopy analysis reveals two time constants and an increase in the charge transfer resistance of the Nyquist plot which suggests a decrease in the conductivity of ITO film with increasing immersion time. Both the electrochemical and surface characterization studies suggest a degradation of the conductivity of ITO film with increasing immersion time in 0.05 M acrylic acid.c acid.

103

Synthesis of bis-(?-trifluoromethylphenyl) dithiophosphinic acid  

International Nuclear Information System (INIS)

The synthetic method of bis-(?-trifluoromethylphenyl) dithiophosphinic acid has been improved during the synthetic research of various dithiophosphinic acids. The optimized synthesis has been realized with PCl3 and (?-F3CC6H4) MgBr as starting materials and via a continuous three-step method including Grignard reaction, sulfuration and substitution reaction. The FTIR spectrum of product shows the presence of substituted aromatic ring, C-F bond, P-S single bond and P=S double bond. The interpretation result f 31P NMR, 1H NMR and 13C NMR of the product, as well as MS, is completely in line with the structure of the targeted compound bis-(?-trifluoromethylphenyl) dithiophosphinic acid. (authors)

104

Effects of ursodeoxycholic acid on synthesis of cholesterol and bile acids in healthy subjects  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Background/Aims: Ursodeoxycholic acid ( UDCA) decreases biliary secretion of cholesterol and is therefore used for the dissolution of cholesterol gallstones. It remains unclear whether these changes in biliary cholesterol excretion are associated with changes in cholesterol synthesis and bile acid synthesis. We therefore studied the activities of rate-limiting enzymes of cholesterol synthesis and bile acid synthesis, 3-hydroxy-3-methyl-glutarylcoenzyme A reductase and cholesterol 7alpha-hydro...

Sauter, G. H.; Thiessen, K.; Parhofer, K. G.; Jungst, C.; Fischer, S.; Jungst, D.

2004-01-01

105

Regulation of ascorbic acid synthesis in plants.  

Science.gov (United States)

Ascorbic acid (AsA) is a major antioxidant and plays an important role in plant growth and development. There are two aspects to improve AsA content, including de novo synthesis and recycling from its oxidized form. However, the knowledge of regulatory mechanisms of AsA synthesis pathways and metabolism still remains limited. We have determined that AsA synthesis process was modulated on both transcriptional and post-transcriptional levels in Arabidopsis. GDP-mannose pyrophosphorylase (VTC1) is the initial AsA biosynthetic enzyme in L-galactose pathway, we previously showed that Arabidopsis ERF98 transcriptionally activates gene expression of VTC1 to improve AsA content and respond salt stress; recent discovery of the interaction between photomorphogenic factor COP9 signalosome (CSN) subunit CSN5B and VTC1 indicates that CSN5B promotes VTC1 degradation in the dark, which keeps the change of AsA content from day to night. This mini-review integrates previous reports and recent evidence to better understand the regulatory mechanisms involved in AsA synthesis. PMID:23603957

Wang, Juan; Zhang, Zhijin; Huang, Rongfeng

2013-06-01

106

Synthesis and NMR characterization of aliphatic-aromatic copolyesters by reaction of poly(ethylene terephthalate) post-consumer and poly(ethylene adipate)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

An aliphatic-aromatic copolyester of poly(ethylene terephthalate), PET, and poly(ethylene adipate), PEA, PET-co-PEA, was synthesized by the high temperature melt reaction of post-consumer PET and PEA. As observed by NMR spectroscopy, the reaction yielded random copolyesters in a few minutes through ester-interchange reactions, even without added catalyst. The copolyesters obtained in the presence of a catalyst presented higher intrinsic viscosity than that obtained without the addition of cat...

Baldissera, Alessandra F.; Vale?rio, Carlos E. S.; Basso, Nara R. S.; Fernando Guaragna; Sandra Einloft; Martine Tessier; Alain Fradet

2005-01-01

107

Free volume and microstructural investigation of poly(ethylene terephthalate)-g -acrylic acid (PET-g-AA) copolymer films  

Science.gov (United States)

Acrylic acid (AA) was grafted onto PET films by preirradiation method using a 60Co ?-radiation source. Microstructural investigation of the PET-g-AA copolymers has been carried out by wide angle X-ray diffraction (WAXD), dynamic mechanical analysis (DMA) and positron annihilation lifetime spectroscopy (PALS) techniques. The WAXD results showed only marginal variation in the crystallinity of the graft copolymers. Dynamic mechanical analysis showed an increase in the temperature of the ?-relaxation and the tan ? value of subroom temperature secondary relaxations. From the PALS results, a complex variation of the free volume parameters, i.e. the o-positronium lifetime ( ?3), its intensity ( I3), fractional free volume ( fv) and the intermediate lifetime component was observed for the graft copolymers. Multiple phenomena of the effect of secondary relaxations, additive behavior of the individual polymer free volume parameters and effects from interfacial defects have been invoked to understand the fluctuational nature of the free volume properties in the graft copolymers.

Rath, S. K.; Patri, M.; Sharma, S. K.; Sudarshan, K.; Pujari, P. K.

2010-07-01

108

Free volume and microstructural investigation of poly(ethylene terephthalate)-g-acrylic acid (PET-g-AA) copolymer films  

International Nuclear Information System (INIS)

Acrylic acid (AA) was grafted onto PET films by preirradiation method using a 60Co ?-radiation source. Microstructural investigation of the PET-g-AA copolymers has been carried out by wide angle X-ray diffraction (WAXD), dynamic mechanical analysis (DMA) and positron annihilation lifetime spectroscopy (PALS) techniques. The WAXD results showed only marginal variation in the crystallinity of the graft copolymers. Dynamic mechanical analysis showed an increase in the temperature of the ?-relaxation and the tan ? value of subroom temperature secondary relaxations. From the PALS results, a complex variation of the free volume parameters, i.e. the o-positronium lifetime (?3), its intensity (I3), fractional free volume (fv) and the intermediate lifetime component was observed for the graft copolymers. Multiple phenomena of the effect of secondary relaxations, additive behavior of the individual polymer free volume parameters and effects from interfacial defects have been invoked to understand the fluctuational nature of the free volume properties in the graft copolymers.

109

Protein synthesis in the presence of carbamoyl-amino acids  

International Nuclear Information System (INIS)

The role of exogenous carbamoyl-amino acids in protein biosynthesis has been examined in vitro using a mixture of 14C amino acids to label newly synthesized protein in human reticulocyte rich (8-18%) peripheral blood. Aliquots of the radiolabeled newly synthesized protein were acid precipitated, washed and the radioactivity measured. Control samples which measured the synthetic capacity of the blood were aliquots of the same blood-14C amino acid mixture without added carbamoyl-amino acids or cyanate. N-carbamoyl leucine alone or a 3 N-carbamoyl amino acid mixture of leucine, aspartic acid and tyrosine were used to test inhibition of protein synthesis. Also carbamoyl-amino acids were synthesized using cyanate and Pierce hydrolyzate amino acid calibration standards or the mixture of 14C amino acids. In this system the carbamoylation of endogenous amino acids by cyanate up to 8 ?mol/100?l showed a linear decrease in protein synthesis with time which is inversely related to the cyanate concentration. At greater cyanate levels the inhibition of protein synthesis reaches a plateau. When N-carbamoyl-amino acids only are present there is about a 50% decrease in the 14C protein at 30 minutes as compared to the synthesis of 14C protein without N-carbamoyl-amino acids. These results indicate that the presence of carbamoyl-amino acids interferes with protein synthesis

110

Hyaluronic acid lipoate: synthesis and physicochemical properties.  

Science.gov (United States)

The synthesis and physicochemical characterisation of mixed lipoic and formic esters of hyaluronan (Lipohyal) are presented in this paper. The synthesis was conducted by activating lipoic acid with 1,1'-carbonyldiimidazole to obtain lipoyl imidazolide, which reacted with hyaluronan (HA) in formamide under basic conditions. This procedure allows researchers to modulate easily the degree of substitution over a range of 0.05-1.8. Radical scavenger properties were analysed by UV-vis spectroscopy, where improved performance was demonstrated for Lipohyal with respect to the HA row material and lipoic acid. The chemical modification also causes HA to show an improved resistance to hyaluronidase digestion. These findings show that Lipohyal is a highly interesting derivative for applications in the tricological and dermo-cosmetic field and as an anti-aging ingredient. Moreover, Lipohyal can be easily crosslinked by UV irradiation, resulting in an innovative hydrogel with distinctive viscoelastic properties that is suitable as both a dermal-filler and as an intra-articular medical device. PMID:23465930

Picotti, Fabrizio; Fabbian, Matteo; Gianni, Rita; Sechi, Alessandra; Stucchi, Luca; Bosco, Marco

2013-03-01

111

21 CFR 177.1315 - Ethylene-1, 4-cyclohexylene dimethylene terephthalate copolymers.  

Science.gov (United States)

...terephthalate or terephthalic acid with a mixture containing 99 to 66 mole percent of ethylene glycol and 1 to 34 mole percent of 1,4-cyclo-hexanedimethanol (70 percent trans isomer, 30 percent cls isomer) Inherent viscosity of a 0.50 percent...

2010-04-01

112

Synthesis and NMR characterization of aliphatic-aromatic co polyesters by reaction of poly(ethylene terephthalate) post-consumer and poly(ethylene adipate)  

Energy Technology Data Exchange (ETDEWEB)

An aliphatic-aromatic copolyester of poly(ethylene terephthalate), PET, and poly(ethylene adipate), PEA, PET-co-PEA, was synthesized by the high temperature melt reaction of post-consumer PET and PEA. As observed by NMR spectroscopy, the reaction yielded random copolyesters in a few minutes through ester-interchange reactions, even without added catalyst. The copolyesters obtained in the presence of a catalyst presented higher intrinsic viscosity than that obtained without the addition of catalyst, due to simultaneous polycondensation and ester-interchange reactions. The structure of the aliphatic-aromatic copolyesters obtained in different PET/PEA ratio is random as observed by NMR analysis. (author)

Baldissera, Alessandra F.; Valerio, Carlos E.S.; Basso, Nara R. de S.; Guaragna, Fernando; Einloft, Sandra [Pontificia Univ. Catolica do Rio Grande do Sul, Porto Alegre, RS (Brazil). Faculdade de Quimica; Tessier, Martine; Fradet, Alain [Universite Pierre et Marie Curie, Paris (France). Chimie des Polymeres. Lab. de Synthese Macromoleculaire

2005-04-01

113

Synthesis and NMR characterization of aliphatic-aromatic co polyesters by reaction of poly(ethylene terephthalate) post-consumer and poly(ethylene adipate)  

International Nuclear Information System (INIS)

An aliphatic-aromatic copolyester of poly(ethylene terephthalate), PET, and poly(ethylene adipate), PEA, PET-co-PEA, was synthesized by the high temperature melt reaction of post-consumer PET and PEA. As observed by NMR spectroscopy, the reaction yielded random copolyesters in a few minutes through ester-interchange reactions, even without added catalyst. The copolyesters obtained in the presence of a catalyst presented higher intrinsic viscosity than that obtained without the addition of catalyst, due to simultaneous polycondensation and ester-interchange reactions. The structure of the aliphatic-aromatic copolyesters obtained in different PET/PEA ratio is random as observed by NMR analysis. (author)

114

Microbial synthesis of triacetic acid lactone.  

Science.gov (United States)

Native g2ps1-encoded 2-pyrone synthase (2-PS) from Gerbera hybrida, a mutant Brevibacterium ammoniagenes fatty acid synthase B (FAS-B) and two different mutants of Penicillium patulum 6-methylsalycilic acid synthase (6-MSAS) are examined to identify the best enzyme to recruit for the microbial synthesis of triacetic acid lactone (TAL). To identify the best microbial host for these evaluations, the native TAL-synthesizing activity of g2ps1-encoded 2-PS is expressed in recombinant Escherichia coli and Saccharomyces cerevisiae constructs. Five-fold higher expression levels of 2-PS are observed in S. cerevisiae. Consequently, microbial synthesis of TAL focuses on S. cerevisiae constructs. Comparison of different promoters for the expression of g2ps1 in S. cerevisiae indicates that the alcohol dehydrogenase II promoter (P(ADH2)) affords the highest expression levels of 2-PS. As a result, the genes encoding the various TAL-synthesizing enzyme activities are expressed in S. cerevisiae from a P(ADH2) promoter. To extend TAL-synthesizing activity beyond g2ps1-encoded 2-PS, the ketoreductase domains of fasB-encoded FAS-B and 6-MSAS-encoded 6-MSAS are modified using a single mutation. Modification of the nicotinamide cofactor-binding site of 6-MSAS with a triple mutation is also examined. Separate S. cerevisiae constructs expressing native g2ps1, mutant Y2226F fasB, mutant Y1572F 6-MSAS, and mutant G1419A-G1421P-G1424A 6-MSAS are cultured under the same fermentor-controlled conditions. The highest concentration (1.8 g/L) and yield (6%) of TAL are synthesized from glucose by S. cerevisiae expressing the Y1572F mutant of 6-MSAS. PMID:16245348

Xie, Dongming; Shao, Zengyi; Achkar, Jihane; Zha, Wenjuan; Frost, John W; Zhao, Huimin

2006-03-01

115

Fatty Acid Synthesis by Indonesian Marine Diatom, Chaetoceros gracilis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Since the primary storage nutrients in diatoms consist of lipid, they are potential for the industrial fatty acid production. High value fatty acids include arachidonic acid, eicosapentaenoic acid and docosahexaenoic acid. This study aimed to analyze fatty acid synthesis by Chaetoceros gracilis diatom during growth. There was a large increase in lipid yield from 4pg cell-1 mass of lipid per cell at the exponential phase to 283pg cell-1 at stationary phase. The lipid concentrations also increa...

ALBERTA RIKA PRATIWI; DAHRUL SYAH; LINAWATI HARDJITO; LILY MARIA GORETTI PANGGABEAN; MAGGY THENAWIDJAJA SUHARTONO

2009-01-01

116

Synthesis of 3C–SiC nanowires by reaction of poly(ethylene terephthalate) waste with SiO{sub 2} microspheres  

Energy Technology Data Exchange (ETDEWEB)

Highlights: •The 3C–SiC nanowires have been synthesized by reaction of poly(ethylene terephthalate) (PET) waste and SiO{sub 2} microspheres as primary reactant. •The recycling of PET wastes are fulfilled, and it is beneficial to the environment protection. •Increasing information will decrease quality if hospital costs are very different. •The prepared 3C–SiC nanowires have a good morphology. •Other polymer wastes, such as PE, PP, PVC, and PS, can also be managed with this method. -- Abstract: 3C–SiC nanowires have been synthesized by reaction of poly(ethylene terephthalate) (PET) waste with SiO{sub 2} microspheres in supercritical carbon dioxide system at 650 °C for 3 h, followed by vacuum annealing at 1500 °C for 4 h. The product was characterized by X-ray diffraction, Raman spectroscopic, Field Emission Scanning Electron Microscopy, and High-resolution Electron Microscopy. The 3C–SiC nanowires are tens of microns in length and 30–150 nm in diameter. It is found that the reaction forming 3C–SiC nanowires take place in the inner of the carbon microspheres generated from PET. The formation mechanism of the 3C–SiC nanowires was discussed.

Gao, Lei; Zhong, Hao; Chen, Qianwang, E-mail: cqw@ustc.edu.cn

2013-07-25

117

Synthesis of 3C–SiC nanowires by reaction of poly(ethylene terephthalate) waste with SiO2 microspheres  

International Nuclear Information System (INIS)

Highlights: •The 3C–SiC nanowires have been synthesized by reaction of poly(ethylene terephthalate) (PET) waste and SiO2 microspheres as primary reactant. •The recycling of PET wastes are fulfilled, and it is beneficial to the environment protection. •Increasing information will decrease quality if hospital costs are very different. •The prepared 3C–SiC nanowires have a good morphology. •Other polymer wastes, such as PE, PP, PVC, and PS, can also be managed with this method. -- Abstract: 3C–SiC nanowires have been synthesized by reaction of poly(ethylene terephthalate) (PET) waste with SiO2 microspheres in supercritical carbon dioxide system at 650 °C for 3 h, followed by vacuum annealing at 1500 °C for 4 h. The product was characterized by X-ray diffraction, Raman spectroscopic, Field Emission Scanning Electron Microscopy, and High-resolution Electron Microscopy. The 3C–SiC nanowires are tens of microns in length and 30–150 nm in diameter. It is found that the reaction forming 3C–SiC nanowires take place in the inner of the carbon microspheres generated from PET. The formation mechanism of the 3C–SiC nanowires was discussed

118

Synthesis of Diaminopimelic Acid, Lysine and Pipecolic Acid from Spartic Acid by Rumen Microorganisms  

Directory of Open Access Journals (Sweden)

Full Text Available The current study was examined the formation of the three Stereoisomers (SI of 2, 6-Diaminopimelic Acid (DAP, lysine and pipecolic acid from aspartic acid by mixed rumen bacteria and protozoa. Mixed rumen bacteria and protozoa were isolated from the rumen of sheep given concentrate mixture and hay and incubated with and without aspartic acid (5 mM. The microbial suspensions were anaerobically incubated at 39°C for 12 h. The results showed that mixed rumen bacteria produced meso-DAP by 0.221 mM, LL-DAP by 0.013 mM, lysine by 0.211 mM during the 12 h incubation periods. This is the first finding to show the synthesis of DAP-SI and lysine from aspartic acid by rumen bacteria. Mixed rumen protozoa produced meso-DAP by 0.231 mM, lysine by 0.443 mM and pipecolic acid by 0.042 mM during the 12 h incubation periods. DD-DAP was not detected during the incubation periods of mixed rumen bacteria and protozoa and also LL-DAP was not detected by mixed rumen protozoa. The synthesis meso-DAP from aspartic acid by rumen protozoa was demonstrated for the first time. The results indicated that mixed rumen bacteria have the ability to synthesis meso-DAP, LL-DAP and lysine from aspartic acid meanwhile, the mixed rumen protozoa have the ability to produced meso-DAP, lysine and pipecolic acid from aspartic acid.

A.M. El-Waziry

2012-01-01

119

Motualevic Acids and Analogs: Synthesis and Antimicrobial Structure Activity Relationships  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Synthesis of the marine natural products motualevic acids A, E, and analogs in which modifications have been made to the ?-brominated lipid (E)-14,14-dibromotetra-deca-2,13-dienoic acid or amino acid unit are reported, together with antimicrobial activities against Staphylococcus aureus, methicillin-resistant S. aureus, Enterococcus faecium, and vancomycin-resistant Enterococcus.

Cheruku, Pradeep; Keffer, Jessica L.; Dogo-isonagie, Cajetan; Bewley, Carole A.

2010-01-01

120

Synthesis and NMR characterization of aliphatic-aromatic copolyesters by reaction of poly(ethylene terephthalate) post-consumer and poly(ethylene adipate)  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english An aliphatic-aromatic copolyester of poly(ethylene terephthalate), PET, and poly(ethylene adipate), PEA, PET-co-PEA, was synthesized by the high temperature melt reaction of post-consumer PET and PEA. As observed by NMR spectroscopy, the reaction yielded random copolyesters in a few minutes through [...] ester-interchange reactions, even without added catalyst. The copolyesters obtained in the presence of a catalyst presented higher intrinsic viscosity than that obtained without the addition of catalyst, due to simultaneous polycondensation and ester-interchange reactions. The structure of the aliphatic-aromatic copolyesters obtained in different PET/PEA ratio is random as observed by NMR analysis.

Alessandra F., Baldissera; Carlos E. S., Valério; Nara. R. de S., Basso; Fernando, Guaragna; Sandra, Einloft; Martine, Tessier; Alain, Fradet.

2005-03-01

 
 
 
 
121

Synthesis and NMR characterization of aliphatic-aromatic copolyesters by reaction of poly(ethylene terephthalate post-consumer and poly(ethylene adipate  

Directory of Open Access Journals (Sweden)

Full Text Available An aliphatic-aromatic copolyester of poly(ethylene terephthalate, PET, and poly(ethylene adipate, PEA, PET-co-PEA, was synthesized by the high temperature melt reaction of post-consumer PET and PEA. As observed by NMR spectroscopy, the reaction yielded random copolyesters in a few minutes through ester-interchange reactions, even without added catalyst. The copolyesters obtained in the presence of a catalyst presented higher intrinsic viscosity than that obtained without the addition of catalyst, due to simultaneous polycondensation and ester-interchange reactions. The structure of the aliphatic-aromatic copolyesters obtained in different PET/PEA ratio is random as observed by NMR analysis.

Alessandra F. Baldissera

2005-03-01

122

Preparation and characterization of polymer blends based on recycled PET and polyester derived by terephthalic acid; Preparacao e caracterizacao de blendas polimericas a base de PET reciclado e poliester derivado do acido tereftalico  

Energy Technology Data Exchange (ETDEWEB)

Environmentally friendly materials, made from industrial waste, are being increasingly used as a solution to the growing amount of waste generated by society, but also as a cheaper alternative to replace conventional materials for use in construction. In this work were investigated the properties of polymer blends based on recycled PET and a polyester derived from terephthalic acid and glycerin, a co-product of biodiesel. The samples were characterized by XRD, TGA, DSC, FTIR and SEM. The polyester synthesized showed a degradation event near 300 deg C. The blends with higher ratio of PET showed thermal behavior similar to pure PET. The X-ray diffraction showed that the polymer blends are semicrystalline materials. The micrographs presents the presence of a smooth surface, indicating the possibility of miscibility between the arrays. Therefore, the blending makes possible the fabrication of low-cost materials with applications in several areas. (author)

Ohara, L.; Miranda, C.S.; Fiuza, R.P.; Luporini, S.; Carvalho, R.F.; Jose, N.M., E-mail: leandro.ohara@gmail.co [Universidade Federal da Bahia (GECIM/UFBA), Salvador, BA (Brazil). Inst. de Quimica. Grupo de Energia e Ciencias dos Materiais

2010-07-01

123

Synthesis of 14C-labelled 1-naphthaleneacetic acid  

International Nuclear Information System (INIS)

A convenient approach to the synthesis of 14C-side chain labelled 1-naphthaleneacetic acids was developed through the reaction of naphthalene with glycolic acid in the presence of ferric oxide and aqueous hydrobromic acid. The various 14C-labelled glycolic acids are readily available intermediates or are easily prepared. The effects of some of the variables on the product yield, such as amounts of naphthalene, ferric oxide, aqueous hydrobromic acid, rate of heating etc. were briefly examined. The product is obtained in 25-30 percent yield (based on glycolic acid), when naphthalene (6 mmol), glycolic acid (1 mmol), ferric oxide (0.6 mg) and aqueous hydrobromic acid (Sp. gr. 1.48, 100 ?l) are heated together to 220 deg C in a sealed tube over an 8 hour period. The synthesis of 14C-carboxyl labelled 1-naphthaleneacetic acid is described. (author). 2 refs.; 3 tabs

124

Synthesis of dimethyl-tartaric acid from aqueous solutions of pyruvic acid induced by ?-rays  

International Nuclear Information System (INIS)

The synthesis of 2,3 dimethyl-tartaric acid (DMTA) can be achieved in one step using pyruvic acid as raw material and ionizing radiation as an energy source. The reaction may have synthetic applications because the reduction product was nearly exclusively DMTA (? 73%) which easily can be isolated and purified. Other products were carbon dioxide, acetic acid and some polycarboxylic acids. (author)

125

Vibrational analysis of polyethylene terephthalate and its deuterated derivatives  

International Nuclear Information System (INIS)

The vibrational analysis of polyethylene terephthalate, polyethylene-d4 terephthalate, and polyethylene terephthalate-d4 was carried out using a valence force field calculated from the infrared and Raman spectra of a series of low molecular weight aromatic esters. The Raman spectra for polyethylene-d4 terephthalate and polyethylene terephthalate-d4 are presented and band assignments for these compounds and polyethylene terephthalate are discussed

126

Synthesis of the isofatty acid 13-methyl-tetradecanoic acid and its triglyceride  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A new and more convenient synthesis of the isofatty acid 13-methyl-tetradecanoic acid and its triglyceride is described here. This isofatty acid is prepared through elongation of the undecanoic acid chain with isobutyraldehyde according to Wittig by the reaction between bromo-undecanoic acid ethyl ester-triphenylphosphonium salt and sodium methoxide followed by the addition of isobutyraldehyde. Its triglyceride is formed by the esterification of the free isofatty acid with glycerin without ca...

Zlatanos, S.; Laskaridis, K.; Koliokota, E.; Sagredos, A.

2011-01-01

127

Prebiotic Amino Acid Thioester Synthesis: Thiol-Dependent Amino Acid Synthesis from Formose substrates (Formaldehyde and Glycolaldehyde) and Ammonia  

Science.gov (United States)

Formaldehyde and glycolaldehyde (substrates of the formose autocatalytic cycle) were shown to react with ammonia yielding alanine and homoserine under mild aqueous conditions in the presence of thiol catalysts. Since similar reactions carried out without ammonia yielded alpha-hydroxy acid thioesters, the thiol-dependent synthesis of alanine and homoserine is presumed to occur via amino acid thioesters-intermediates capable of forming peptides. A pH 5.2 solution of 20 mM formaldehyde, 20 mM glycolaldehyde, 20 mM ammonium chloride, 23 mM 3-mercaptopropionic acid, and 23 mM acetic acid that reacted for 35 days at 40 C yielded (based on initial formaldehyde) 1.8% alanine and 0.08% homoserine. In the absence of thiol catalyst, the synthesis of alanine and homoserine was negligible. Alanine synthesis required both formaldehyde and glycolaldehyde, but homoserine synthesis required only glycolaldehyde. At 25 days the efficiency of alanine synthesis calculated from the ratio of alanine synthesized to formaldehyde reacted was 2.1%, and the yield (based on initial formaldehyde) of triose and tetrose intermediates involved in alanine and homoserine synthesis was 0.3 and 2.1%, respectively. Alanine synthesis was also seen in similar reactions containing only 10 mM each of aldehyde substrates, ammonia, and thiol. The prebiotic significance of these reactions that use the formose reaction to generate sugar intermediates that are converted to reactive amino acid thioesters is discussed.

Weber, Arthur L.

1998-01-01

128

The synthesis and some properties of nylon 4,T  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The synthesis of nylon 4,T from tetramethylenediamine and a terephthalic acid derivative was studied in a two step-process: prepolymerization, followed by postcondensation in the solid state (4 h, 290°C). The prepolymers were prepared by the nylon salt method, ester polymerization method, interfacial method, and a low temperature solution method. A maximum ?inh of 1.52 was obtained. From a solution in trifluoroacetic acid, films were cast and on these films we studied its IR spectrum, WAXS,...

Gaymans, R. J.

1985-01-01

129

Enzymatic synthesis of chiral ?-amino acids using ?-transaminase.  

Science.gov (United States)

In this study, we successfully synthesized enantiomerically pure (R)- and (S)-?-amino acids (>99% ee) using ?-transaminase (?-TA) through kinetic resolution and asymmetric synthesis respectively. The present study demonstrates the high potentiality of ?-TA reaction for the production of chiral ?-amino acids. PMID:25207334

Shon, Minsu; Shanmugavel, Ramachandran; Shin, Giyoung; Mathew, Sam; Lee, Sang-Hyeup; Yun, Hyungdon

2014-10-28

130

Oleochemical synthesis of an acid cleavable hydrophobe for surfactant use  

Science.gov (United States)

The synthesis of a series of branched hydroxy stearates from commercially available methyl oleate and common organic acids is reported. A variety of different acids, with 3 to 8 carbon atoms, and also varying in their branching and functionality, were used. The kinetics of the ring opening reactio...

131

An alternative convenient synthesis of piperidazine-3-carboxylic acid derivatives.  

Science.gov (United States)

The short-step synthesis of the unsubstituted, 5-hydroxy- and 5-chloropiperidazine-3-carboxylic acids using an aza Diels-Alder reaction between the 1,3-diene and azodicarboxylate was described. This synthetic methodology could be used for the preparation of the optically active piperazic acid in a 35% overall yield. PMID:19122315

Kaname, Mamoru; Yamada, Masae; Yoshifuji, Shigeyuki; Sashida, Haruki

2009-01-01

132

Synthesis of sulfate esters of lithocholic acid, glycolithocholic acid, and taurolithocholic acid with sulfur trioxide-triethylamine.  

Science.gov (United States)

The facile synthesis of lithocholic acids sulfates by a procedure that produced the desired products in over 90% yield is described. Lithocholic acid sulfate and glycolithocholic acid sulfate were synthesized by reacting lithocholic acid or glycolithocholic acid with sulfur trioxide-triethylamine complex in dimethylformamide for 0.5-1 hr. Taurolithocholic acid sulfate was obtained by conjugating lithocholic acid sulfate with taurine in dimethylformamide at 90 degrees C for 0.5 hr. The one-pot synthesis of taurolithocholic acid sulfate starting from lithocholic acid is also described. This procedure, which generated lithocholic acid sulfate in situ, produced taurolithocholic acid sulfate in 98% yield, compared to an overall yield of less than 10% obtained by previously published procedures. PMID:894140

Tserng, K Y; Klein, P D

1977-07-01

133

The synthesis of glutamic acid in the absence of enzymes: Implications for biogenesis  

Science.gov (United States)

This paper reports on the non-enzymatic aqueous phase synthesis of amino acids from keto acids, ammonia and reducing agents. The facile synthesis of key metabolic intermediates, particularly in the glycolytic pathway, the citric acid cycle, and the first step of amino acid synthesis, lead to new ways of looking at the problem of biogenesis.

Morowitz, Harold; Peterson, Eta; Chang, Sherwood

1995-01-01

134

Acetylsalicylic acid: Incoming 150 years of the first synthesis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Acetylsalicylic acid is one of the most fascinating and versatile drugs known to medicine, as well as one of the oldest. Acetylsalicylic acid is a drug which is safe, with analgetic, antirheumatic, anti-inflammatory antiplatelet and antithrombotic action. It may be applied not only in clinical practice, but also as prevention. The first known use of an acetylsalicylic acid-like preparation can be traced to ancient Greece. In 1853 Charles Gerhardt published the first synthesis of acetylsalicyl...

Z?, Mijin Dus?an; Stankovi? Milena; Petrovi? Slobodan D.; Blagojevi? Milorad

2002-01-01

135

Differential diagnosis in patients with suspected bile acid synthesis defects  

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AIM: To investigate the clinical presentations associated with bile acid synthesis defects and to describe identification of individual disorders and diagnostic pitfalls. METHODS: Authors describe semiquantitative determination of 16 urinary bile acid metabolites by electrospray ionization-tandem mass spectrometry. Sample preparation was performed by solid-phase extraction. The total analysis time was 2 min per sample. Authors determined bile acid metabolites in 363 patients with suspected de...

Dorothea Haas; Hongying Gan-Schreier; Claus-Dieter Langhans; Tilman Rohrer; Guido Engelmann; Maura Heverin; Russell, David W.; Clayton, Peter T.; Hoffmann, Georg F.; Okun, J. Xfc Rgen G.

2012-01-01

136

Effects of bile acid administration on bile acid synthesis and its circadian rhythm in man  

International Nuclear Information System (INIS)

In man bile acid synthesis has a distinct circadian rhythm but the relationship of this rhythm to feedback inhibition by bile acid is unknown. We measured bile acid synthesis as release of 14CO2 from [26-14C]cholesterol every 2 hr in three normal volunteers during five separate 24-hr periods. Data were fitted by computer to a cosine curve to estimate amplitude and acrophase of the circadian rhythm. In an additional six volunteers, we measured synthesis every 2 hr from 8:00 a.m. to 4:00 p.m. only. During the control period, amplitude (expressed as percentage of mean synthesis) averaged 52% and acrophase averaged 6:49 a.m. During administration of ursodeoxycholic acid (15 mg per kg per day), synthesis averaged 126% of baseline (p less than 0.1), amplitude averaged 43% and acrophase averaged 6:20 a.m. During administration of chenodeoxycholic acid (15 mg per kg per day), synthesis averaged 43% of baseline (p less than 0.001), amplitude averaged 53% and acrophase averaged 9:04 a.m. Addition of prednisone to this regimen of chenodeoxycholic acid to eliminate release of 14CO2 from corticosteroid hormone synthesis resulted in a mean amplitude of 62% and a mean acrophase of 6:50 a.m., values very similar to those in the baseline period. Administration of prednisone alone also did not significantly alter the baseline amplitude (40%) or acrophase (6:28 a.m.). We conclude that neither chenodeoxycholic acid nor ursodeoxycholic acid significantly alters the circadian rhythm of bilicantly alters the circadian rhythm of bile acid synthesis in man

137

Effects of bile acid administration on bile acid synthesis and its circadian rhythm in man  

Energy Technology Data Exchange (ETDEWEB)

In man bile acid synthesis has a distinct circadian rhythm but the relationship of this rhythm to feedback inhibition by bile acid is unknown. We measured bile acid synthesis as release of 14CO2 from (26-14C)cholesterol every 2 hr in three normal volunteers during five separate 24-hr periods. Data were fitted by computer to a cosine curve to estimate amplitude and acrophase of the circadian rhythm. In an additional six volunteers, we measured synthesis every 2 hr from 8:00 a.m. to 4:00 p.m. only. During the control period, amplitude (expressed as percentage of mean synthesis) averaged 52% and acrophase averaged 6:49 a.m. During administration of ursodeoxycholic acid (15 mg per kg per day), synthesis averaged 126% of baseline (p less than 0.1), amplitude averaged 43% and acrophase averaged 6:20 a.m. During administration of chenodeoxycholic acid (15 mg per kg per day), synthesis averaged 43% of baseline (p less than 0.001), amplitude averaged 53% and acrophase averaged 9:04 a.m. Addition of prednisone to this regimen of chenodeoxycholic acid to eliminate release of 14CO2 from corticosteroid hormone synthesis resulted in a mean amplitude of 62% and a mean acrophase of 6:50 a.m., values very similar to those in the baseline period. Administration of prednisone alone also did not significantly alter the baseline amplitude (40%) or acrophase (6:28 a.m.). We conclude that neither chenodeoxycholic acid nor ursodeoxycholic acid significantly alters the circadian rhythm of bile acid synthesis in man.

Pooler, P.A.; Duane, W.C.

1988-09-01

138

Scientific Opinion on the safety evaluation of the active substances, terephthalic acid, dimethyl ester , polymer with 1,4-butanediol, cyclized, polymers with glycidyl methacrylate, hydroxyl-terminated polybutadiene, methyl methacrylate and styrene, and cobalt stearate for use in food contact materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This scientific opinion of EFSA deals with the safety evaluation of the oxygen absorber (terephthalic acid, dimethyl ester, polymer with 1,4-butanediol, cyclized, polymers with glycidyl methacrylate, hydroxyl-terminated polybutadiene, methyl methacrylate and styrene) copolymer (CAS No 1223402-34-3, FCM substance No 1005) and the oxidation catalyst cobalt stearate (CAS No 1002-88-6 and FCM Substance No 1004), intended to be used up to a maximum percentage of 1% in polyethylene terepht...

Efsa Panel On Food Contact Materials, Enzymes

2012-01-01

139

Synthesis of anti and syn hydroxy-iso-evoninic acids.  

Science.gov (United States)

The first synthesis of hydroxy-iso-evoninic acid (2), a pyridyl diacid found as a macrodilactone bridging ligand in bioactive Celastraceae sesquiterpenoid-based natural products, has been achieved in 9 steps and an overall yield of 26%. The synthesis utilizes a benzilic ester rearrangement (BER) and a late stage benzylic oxidation to give access to all four stereoisomers whose absolute stereochemistry was assigned following chromatographic separation and anomalous dispersion X-ray crystallography. PMID:22592593

Warren, Sarah A; Stokes, Stephen; Frampton, Christopher S; White, Andrew J P; Spivey, Alan C

2012-06-28

140

Involvement of plasmid deoxyribonucleic acid in indoleacetic acid synthesis in Pseudomonas savastanoi.  

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Olive (or oleander) knot is a plant disease incited by Pseudomonas savastanoi. Disease symptoms consist of tumorous outgrowths induced in the plant by bacterial production of indole-3-acetic acid (IAA). Synthesis of IAA occurs by the following reactions: L-tryptophan leads to indoleacetamide leads to indoleacetic acid, catalyzed by tryptophan 2-monooxygenase and indoleacetamide hydrolase, respectively. Whereas the enzymology of IAA synthesis is well characterized, nothing is known about the g...

Comai, L.; Kosuge, T.

1980-01-01

 
 
 
 
141

Synthesis of new fatty acids amides from aminolysis of fatty acid methyl esters (FAMEs)  

International Nuclear Information System (INIS)

Recent biochemical and pharmacological studies have led to the characterization of different fatty acid amides as a new family of biologically active lipids. Here, we describe the synthesis of new amides from C16:0, 18:0, 18:1 and 18:1, OH fatty acids (FFA) families with cyclic and acyclic amines and demonstrate for the first time that these compounds produce cytotoxic effects. Application of this method to the synthesis of fatty acid amides was performed using the esters aminolysis as a key step and various carboxylic amides were prepared in good yield from fatty acid methyl esters (FAMEs). (author)

142

Differential diagnosis in patients with suspected bile acid synthesis defects  

Directory of Open Access Journals (Sweden)

Full Text Available AIM: To investigate the clinical presentations associated with bile acid synthesis defects and to describe identification of individual disorders and diagnostic pitfalls. METHODS: Authors describe semiquantitative determination of 16 urinary bile acid metabolites by electrospray ionization-tandem mass spectrometry. Sample preparation was performed by solid-phase extraction. The total analysis time was 2 min per sample. Authors determined bile acid metabolites in 363 patients with suspected defects in bile acid metabolism. RESULTS: Abnormal bile acid metabolites were found in 36 patients. Two patients had bile acid synthesis defects but presented with atypical presentations. In 2 other patients who were later shown to be affected by biliary atresia and cystic fibrosis the profile of bile acid metabolites was initially suggestive of a bile acid synthesis defect. Three adult patients suffered from cerebrotendinous xanthomatosis. Nineteen patients had peroxisomal disorders, and 10 patients had cholestatic hepatopathy of other cause. CONCLUSION: Screening for urinary cholanoids should be done in every infant with cholestatic hepatopathy as well as in children with progressive neurological disease to provide specific therapy.

Dorothea Haas

2012-01-01

143

Regulation of collagen synthesis by ascorbic acid.  

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After prolonged exposure to ascorbate, collagen synthesis in cultured human skin fibroblasts increased approximately 8-fold with no significant change in synthesis of noncollagen protein. This effect of ascorbate appears to be unrelated to its cofactor function in collagen hydroxylation. The collagenous protein secreted in the absence of added ascorbate was normal in hydroxylysine but was mildly deficient in hydroxyproline. In parallel experiments, lysine hydroxylase (peptidyllysine, 2-oxoglu...

Murad, S.; Grove, D.; Lindberg, K. A.; Reynolds, G.; Sivarajah, A.; Pinnell, S. R.

1981-01-01

144

Synthesis of imidazol-1-yl-acetic acid hydrochloride: A key intermediate for zoledronic acid  

Directory of Open Access Journals (Sweden)

Full Text Available A convenient and practical synthesis of imidazol-1-yl-acetic acid hydrochloride was achieved via N-alkylation of imidazole using tert-butyl chloroacetate followed by a non-aqueous ester cleavage of the resulting imidazol-1-yl-acetic acid tert-butyl ester in the presence of titanium tetrachloride. The synthesized imidazol-1-yl-acetic acid hydrochloride was then utilized to prepare zoledronic acid.

2008-11-01

145

Biobased synthesis of acrylonitrile from glutamic acid  

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Glutamic acid was transformed into acrylonitrile in a two step procedure involving an oxidative decarboxylation in water to 3-cyanopropanoic acid followed by a decarbonylation-elimination reaction using a palladium catalyst

Le Notre, J. E. L.; Scott, E. L.; Franssen, M. C. R.; Sanders, J. P. M.

2011-01-01

146

Comparison of bile acid synthesis determined by isotope dilution versus fecal acidic sterol output in human subjects  

International Nuclear Information System (INIS)

Fecal acidic sterol output has been found to be much lower than bile acid synthesis determined by isotope dilution. Because of this confusing discrepancy, we compared these 2 measurements done simultaneously on 13 occasions in 5 normal volunteers. In contrast to previous findings, bile acid synthesis by the Lindstedt isotope dilution method averaged 16.3% lower than synthesis simultaneously determined by fecal acidic sterol output (95% confidence limit for the difference - 22.2 to -10.4%). When one-sample determinations of bile acid pools were substituted for Lindstedt pools, bile acid synthesis by isotope dilution averaged 5.6% higher than synthesis by fecal acidic sterol output (95% confidence limits -4.9 to 16.1%). These data indicate that the 2 methods yield values in reasonably close agreement with one another. If anything, fecal acidic sterol outputs are slightly higher than synthesis by isotope dilution

147

Catalytic synthesis and decomposition of peroxycarboxylic acids  

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The purpose of this thesis was to find a way to produce peroxycarboxylic acid from hydrogen peroxide and carboylic acid in a continuous reactor by using heterogeneous catalysts. In the first step the stability of peroxyde species xas studied by using an online analytic method (Mass spectrometer). One of the main challenge was to find a suitable solid acid catalyst, wich does no decompose the peroxyde species and can catalyze the reaction as sulfuric acid. A continuous fixed bed reactor was bu...

Leveneur, Se?bastien

2009-01-01

148

Enzymatic synthesis of [3-14C] cinnamic acid  

International Nuclear Information System (INIS)

Convenient and efficient route of the synthesis of [3-14C] cinnamic acid is reported. [1-14C] Benzoic acid, prepared by carbonation of Grignard reagent with [14C] carbon dioxide, was reduced to [1-14C] benzyl alcohol. In the enzymatic step this alcohol was selectively oxidised to [1-14C] benzaldehyde using enzyme YADH (Ec. 1.1.1.1) and immediately condensed with malonic acid. This combined chemical and enzymatic approach allows to obtain [3-14C] cinnamic acid with radiochemical yield higher than 50% in respect to the starting alcohol. (author)

149

Synthesis of itaconic acid from the irradiation of aconitic acid-clay suspensions  

International Nuclear Information System (INIS)

The radiolysis of aconitic acid in aqueous solution and in water-clay suspensions was studied. Among the radiolytic products, itaconic acid (HO2C-C(=CH2)-CH2CO2H) was formed. Itaconic acid is a valuable monomer in the formulation of polymers. The synthesis of itaconic acid can be achieved in one step using aqueous solutions of aconitic acid and in water-clay suspensions exposed to ionizing radiation. The yield of formation does not compete with fermentation procedures for the synthesis of itaconic acid, but for laboratory purposes is a very simple method to prepare it. Other products of the radiolysis were carbon dioxide, tricarballylic and citric/isocitric acids. (Author)

150

The Strecker synthesis as a source of amino acids in carbonaceous chondrites: deuterium retention during synthesis.  

Science.gov (United States)

Deuterium-enriched amino acids occur in the Murchison carbonaceous chondrite. Synthesis from D-enriched interstellar precursors by Strecker reactions during aqueous alteration of the parent body has been proposed. To test this hypothesis, we have measured the retention of deuterium in amino acids produced from HCN, NH3, and formaldehyde-D2, acetaldehyde-D4, and acetone-D6 in H2O. The isotopic label is 50% to 98% retained, with variations in retentivity depending on the amino acid and the reaction conditions. If amino acids, once formed on the parent body by the Strecker synthesis, lose no deuterium by subsequent exchange with water or H-bearing minerals, then the observed deuterium isotopic composition of Murchison amino acids represents as much as 50% or more of the enrichments inherited from their interstellar precursors. Imino diacids are prominent side products of the Strecker synthesis which have not been reported in carbonaceous chondrites. Under the conditions of the Strecker reaction using deuterium labeled aldehydes and ketones, unlabeled amino acids are also formed by an HCN polymerization route indicating multiple pathways for the synthesis of amino acids in meteorites. PMID:11539581

Lerner, N R; Peterson, E; Chang, S

1993-10-01

151

Synthesis of biobased succinonitrile from glutamic acid and glutamine.  

Science.gov (United States)

Succinonitrile is the precursor of 1,4-diaminobutane, which is used for the industrial production of polyamides. This paper describes the synthesis of biobased succinonitrile from glutamic acid and glutamine, amino acids that are abundantly present in many plant proteins. Synthesis of the intermediate 3-cyanopropanoic amide was achieved from glutamic acid 5-methyl ester in an 86 mol% yield and from glutamine in a 56 mol?% yield. 3-Cyanopropanoic acid can be converted into succinonitrile, with a selectivity close to 100% and a 62% conversion, by making use of a palladium(II)-catalyzed equilibrium reaction with acetonitrile. Thus, a new route to produce biobased 1,4-diaminobutane has been discovered. PMID:21557494

Lammens, Tijs M; Le Nôtre, Jérôme; Franssen, Maurice C R; Scott, Elinor L; Sanders, Johan P M

2011-06-20

152

Cyclic phosphatidic acid and lysophosphatidic acid induce hyaluronic acid synthesis via CREB transcription factor regulation in human skin fibroblasts.  

Science.gov (United States)

Cyclic phosphatidic acid (cPA) is a naturally occurring phospholipid mediator and an analog of the growth factor-like phospholipid lysophosphatidic acid (LPA). cPA has a unique cyclic phosphate ring at the sn-2 and sn-3 positions of its glycerol backbone. We showed before that a metabolically stabilized cPA derivative, 2-carba-cPA, relieved osteoarthritis pathogenesis in vivo and induced hyaluronic acid synthesis in human osteoarthritis synoviocytes in vitro. This study focused on hyaluronic acid synthesis in human fibroblasts, which retain moisture and maintain health in the dermis. We investigated the effects of cPA and LPA on hyaluronic acid synthesis in human fibroblasts (NB1RGB cells). Using particle exclusion and enzyme-linked immunosorbent assays, we found that both cPA and LPA dose-dependently induced hyaluronic acid synthesis. We revealed that the expression of hyaluronan synthase 2 messenger RNA and protein is up-regulated by cPA and LPA treatment time dependently. We then characterized the signaling pathways up-regulating hyaluronic acid synthesis mediated by cPA and LPA in NB1RGB cells. Pharmacological inhibition and reporter gene assays revealed that the activation of the LPA receptor LPAR1, Gi/o protein, phosphatidylinositol-3 kinase (PI3K), extracellular-signal-regulated kinase (ERK), and cyclic adenosine monophosphate response element-binding protein (CREB) but not nuclear factor ?B induced hyaluronic acid synthesis by the treatment with cPA and LPA in NB1RGB cells. These results demonstrate for the first time that cPA and LPA induce hyaluronic acid synthesis in human skin fibroblasts mainly through the activation of LPAR1-Gi/o followed by the PI3K, ERK, and CREB signaling pathway. PMID:24845645

Maeda-Sano, Katsura; Gotoh, Mari; Morohoshi, Toshiro; Someya, Takao; Murofushi, Hiromu; Murakami-Murofushi, Kimiko

2014-09-01

153

New catalytic processes for the synthesis of adipic acid  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The aim of my Ph.D. research was to study the new synthetic ways for the production of adipic acid. Three different pathways were studied: i) oxidation of cyclohexanone with molecular oxygen using Keggin – heteropolycompounds as the catalyst, ii) Baeyer – Villiger oxidation of cyclohexanone with hydrogen peroxide in the presence of two different heterogeneous catalysts, titanium silicalite and silica grafted decatungstate, iii) two step synthesis of adipic acid starting from cyclohex...

Raabova?, Katerina

2011-01-01

154

Synthesis of p-(Di-n-propylsulphamyl Benzoic Acid  

Directory of Open Access Journals (Sweden)

Full Text Available A process for the synthesis of p-carboxybenzene sulphonylchloride by oxidation of toluene-p-sulphonylchloride as well as toluene-p-sulphonic acid has been developed. p-carboxybenzene sulphonylchloride on condensation with di-n-propylamine yield p-(di-n-propylsulphamyl -benzoic acid, an uricusuric agent employed in chronic gouty arthritis and used as an antiuric adjuvant known in trade as "Benemid, Probenecid".

S. K. Shukla

2014-05-01

155

Stereoselective synthesis of conformationally constrained omega-amino acid analogues from pyroglutamic acid.  

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Bicyclic lactams derived from pyroglutamic acid provide a useful scaffold for synthesis of conformationally restricted analogues of lysine, ornithine and glutamine, as well as an Ala-Ala dipeptide analogue. Amino alcohol and carboxylic acid derivatives are accessible from a common intermediate. In this strategy, the bicyclic lactam system not only controls, but also facilitates the determination of the stereochemistry of the synthetic intermediates.

Bentz, El; Goswami, R.; Moloney, Mg; Westaway, Sm

2005-01-01

156

Microwave-Assisted One-Step Synthesis of Fenamic Acid Hydrazides from the Corresponding Acids  

Directory of Open Access Journals (Sweden)

Full Text Available A facile and efficient method for synthesis of fenamic acid hydrazides from their acids in one-step reaction under microwave irradiation and solvent-free conditions was developed. Compared with the two-step conventional heating method, the process was simple, the reaction time was very short and the yields were almost quantitative.

Tilal Al-Samani

2011-04-01

157

Microwave-Assisted One-Step Synthesis of Fenamic Acid Hydrazides from the Corresponding Acids  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A facile and efficient method for synthesis of fenamic acid hydrazides from their acids in one-step reaction under microwave irradiation and solvent-free conditions was developed. Compared with the two-step conventional heating method, the process was simple, the reaction time was very short and the yields were almost quantitative.

Tilal Al-Samani; Pervez Ahmad; Ahmed Bari; Adnan Kadi; Abdel-aziz, Hatem A.; Tarek Aboul-Fadl; Seik Weng Ng

2011-01-01

158

Synthesis and characterization of polyamide and polyester, from glycerol and dicarboxylic acids, polymeric blends  

International Nuclear Information System (INIS)

In this work were prepared and characterized polyamide and polyester blends. The polyester, called PAT, was produced in a becker equipped with high-torque mechanical stirrer, thermometer and condenser Claisen, by adding of glycerol, adipic acid, terephthalic acid and catalyst. The blends films were prepared by physical mixture followed by thermal compression. The polymeric blends and the pure materials were characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that the blends are semi-crystalline and have good thermal behavior, besides, it evidences that the PAT and polyamide phases are immiscible. (author)

159

The synthesis and biological activity of some bile acid derivatives  

International Nuclear Information System (INIS)

In this monograph authors present the modified technologic scheme of receiving of 3?, 7?, 12?-three hydro xi cholanic acid with using of available raw materials for the synthesis products and for receiving on its base drugs diluent cholesterol gallstones of gall-bladder and bile-ducts

160

Asymmetric synthesis of \\alpha-methoxyarylacetic acid derivatives  

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Stereoselective synthesis of a series of 2-aryl-2-methoxyethanols was achieved from inexpensive chiral pool tartaric acid employing a diastereoselective reduction of a symmetrical 1,4-diaryldiketone as the key step. 2-Aryl-2-methoxyethanols were enantioselectively prepared in 80-90% yield.

Prasad, Kavirayani R.; Chandrakumar, Appayee

2005-01-01

 
 
 
 
161

Synthesis of Bosutinib from 3-Methoxy-4-hydroxybenzoic Acid  

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This paper reports a novel synthesis of bosutinib starting from 3-methoxy-4-hydroxybenzoic acid. The process starts with esterification of the starting material, followed by alkylation, nitration, reduction, cyclization, chlorination and two successive amination reactions. The intermediates and target molecule were characterized by 1H-NMR, 13C-NMR, MS and the purities of all the compounds were determined by HPLC.

Xiao Jia Yin; Guan Hong Xu; Xu Sun; Yan Peng; Xing Ji; Ke Jiang; Fei Li

2010-01-01

162

Synthesis and hypoglycemic evaluation of substituted pyrazole-4-carboxylic acids.  

Science.gov (United States)

The synthesis and in vivo activities of a series of substituted pyrazole-4-carboxylic acids as hypoglycemic agents are described. Modelization of some potent compounds, comparatively to the metformine, presents certain analogies permitting to predict the design of some novel antidiabetic drugs. PMID:12127514

Cottineau, Bertrand; Toto, Patrick; Marot, Christophe; Pipaud, Aline; Chenault, Jacques

2002-08-19

163

Enzymatic routes for the synthesis of ursodeoxycholic acid.  

Science.gov (United States)

Ursodeoxycholic acid, a secondary bile acid, is used as a drug for the treatment of various liver diseases, the optimal dose comprises the range of 8-10mg/kg/day. For industrial syntheses, the structural complexity of this bile acid requires the use of an appropriate starting material as well as the application of regio- and enantio-selective enzymes for its derivatization. Most strategies for the synthesis start from cholic acid or chenodeoxycholic acid. The latter requires the conversion of the hydroxyl group at C-7 from ?- into ?-position in order to obtain ursodeoxycholic acid. Cholic acid on the other hand does not only require the same epimerization reaction at C-7 but the removal of the hydroxyl group at C-12 as well. There are several bacterial regio- and enantio-selective hydroxysteroid dehydrogenases (HSDHs) to carry out the desired reactions, for example 7?-HSDHs from strains of Clostridium, Bacteroides or Xanthomonas, 7?-HSDHs from Clostridium, Collinsella, or Ruminococcus, or 12?-HSDH from Clostridium or from Eggerthella. However, all these bioconversion reactions need additional steps for the regeneration of the coenzymes. Selected multi-step reaction systems for the synthesis of ursodeoxycholic acid are presented in this review. PMID:25131646

Eggert, Thorsten; Bakonyi, Daniel; Hummel, Werner

2014-12-10

164

Selective Synthesis of Citric Acid from Molasses using Aspergillus Niger  

Directory of Open Access Journals (Sweden)

Full Text Available Selective synthesis of Citric Acid from local cane molasses using Aspergillus niger was studied. A local stain of A.niger isolated from lemon tree leaves & cultured. A.niger stain ATCC-595 were separately studied for the Bioconversion of local molasses into citric acid. The molasses fermentation was carried out at 30°C in a flask. The results showed increased efficiency for citric acid production when compared with wild type. It produced 210.12 gm/lit of citric acid as compared to wild stain 102.5 gm/lit. The maximum citric acid production is on the 9th day of fermentation by used stain and 11th day by the wild type. This investigation is one of the ecofriendly technology can be used for economic development & environmental protection in india. By recycling & reusing waste material from cane Industries Citric acid production can be easily done.

Jayant.K.Pohnerkar

2014-03-01

165

Amino Acid Synthesis in a Supercritical Carbon Dioxide - Water System  

Directory of Open Access Journals (Sweden)

Full Text Available Mars is a CO2-abundant planet, whereas early Earth is thought to be also CO2-abundant. In addition, water was also discovered on Mars in 2008. From the facts and theory, we assumed that soda fountains were present on both planets, and this affected amino acid synthesis. Here, using a supercritical CO2/liquid H2O (10:1 system which mimicked crust soda fountains, we demonstrate production of amino acids from hydroxylamine (nitrogen source and keto acids (oxylic acid sources. In this research, several amino acids were detected with an amino acid analyzer. Moreover, alanine polymers were detected with LC-MS. Our research lights up a new pathway in the study of life’s origin.

Akiyoshi Hoshino

2009-06-01

166

Stereoselective synthesis of stable-isotope-labeled amino acids  

Energy Technology Data Exchange (ETDEWEB)

For magnetic resonance and vibrational spectroscopies to reach their full potential, they must be used in combination with sophisticated site-specific stable isotope labeling of biological macromolecules. Labeled amino acids are required for the study of the structure and function of enzymes and proteins. Because there are 20 common amino acids, each with its own distinguishing chemistry, they remain a synthetic challenge. The Oppolzer chiral auxiliary provides a general tool with which to approach the synthesis of labeled amino acids. By using the Oppolzer auxiliary, amino acids can be constructed from several small molecules, which is ideal for stable isotope labeling. In addition to directing the stereochemistry at the {alpha}-carbon, the camphorsultam can be used for stereo-specific isotope labeling at prochiral centers in amino acids. By using the camphorsultam auxiliary we have the potential to synthesize virtually any isotopomer of all of the common amino acids.

Unkefer, C.J.; Martinez, R.A.; Silks, L.A. III [Los Alamos National Laboratory, NM (United States); Lodwig, S.N. [Centralia College, WA (United States)

1994-12-01

167

76 FR 54791 - Polyethylene Terephthalate (PET) Film From Korea  

Science.gov (United States)

...731-TA-459; Third Review] Polyethylene Terephthalate (PET) Film From Korea...antidumping duty order on polyethylene terephthalate (PET) film from Korea...August 2011), entitled Polyethylene Terephthalate (PET) Film from...

2011-09-02

168

Photolabile linker for the synthesis of hydroxamic acids  

DEFF Research Database (Denmark)

The present invention relates to a photolabile hydroxamate linker based on the o - nitroveratryl group and its application for multistep solid-phase synthesis and controlled photolytic release of hydroxamic acids. The invention provides a method for producing a solid support comprising a hydroxylamine - functionalized photolabile linker, and the so produced hydroxylamine - functionalized photolabile solid support. The invention further provides a method for synthesizing a one-bead-one compound library of hydroxamic acid derivatives on a photolabile linker, as well as a method for screening a library of hydroxamic acid derivatives.

Nielsen, Thomas Eiland Technical University of Denmark,

169

Synthesis and anticonvulsant activity of novel bicyclic acidic amino acids  

DEFF Research Database (Denmark)

Bicyclic acidic amino acids (+/-)-6 and (+/-)-7, which are conformationally constrained homologues of glutamic acid, were prepared via a strategy based on a 1,3-dipolar cycloaddition. The new amino acids were tested toward ionotropic and metabotropic glutamate receptor subtypes; both of them behaved as antagonists at mGluR1,5 and as agonists at mGluR2. Furthermore, whereas (+/-)-6 was inactive at all ionotropic glutamate receptors, (+/-)-7 displayed a quite potent antagonism at the NMDA receptors. In the in vivo tests on DBA/2 mice, the compounds displayed an anticonvulsant activity. The interesting pharmacological profile of (+/-)-7 qualifies it as a lead of novel neuroprotective agents.

Conti, Paola; De Amici, Marco

2003-01-01

170

Role of primary and secondary bile acids as feedback inhibitors of bile acid synthesis in the rat in vivo.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The effect of various primary and secondary bile acids on the rates of synthesis of all major bile acids was studied in the live rat with an extracorporal bile duct. Bile acid synthesis was determined using HPLC based on mass or by isotope dilution. Derepressed rates of bile acid synthesis (30-54 h) were inhibited by an infusion of taurocholic acid only at a supraphysiological dose of 500 mumol/kg per h, but not at 300 mumol/kg per h, which approximates the initial bile acid secretion (250 mu...

Stange, E. F.; Scheibner, J.; Ditschuneit, H.

1989-01-01

171

The optimisation study of tbp synthesis process by phosphoric acid  

International Nuclear Information System (INIS)

The present work deals with the optimisation study of TBP synthesis process by phosphoric acid. This way of synthesis is more advantageous than POCL3 or P2O5 as phosphatant agents. these latters are toxic and dangerous for the environnement. The optimisation study is based on a series of 16 experiences taking into account the range of variation of the following parameters : temperature, pressure, reagents mole ratio, promoter content. the yield calculation is based on the randomisation of an equation including all parameters. the resolution of this equation gave a 30% TBP molar ratio. this value is in agreement with that of experimental data

172

Synthesis of new ?(2,2)-amino acids with carbohydrate side chains: impact on the synthesis of peptides.  

Science.gov (United States)

The study describes the synthesis of new geminally disubstituted C-linked carbo-?(2,2)-amino acids (?(2,2)-Caas) with different carbohydrate side chains, and their use in the synthesis of ?(2,2)-peptides. The study infers that the side chain has an influence on the synthesis of peptides and their conformational behaviour. PMID:24594528

Sharma, Gangavaram V M; Rajender, Karnekanti; Sridhar, Gattu; Reddy, Post Sai; Kanakaraju, Marumudi

2014-03-31

173

Synthesis of Symmetric Dithiophosphinic Acids for "Minor Actinide" Extraction  

Energy Technology Data Exchange (ETDEWEB)

New dithiophosphinic acid (DPAH) derivatives were isolated using a synthetic pathway which provides the control of regiochemistry and/or stereochemistry of the products. The synthesis improves DPAH designs that can address the issues about the separation between trivalent actinides and lanthanides. The synthesis is straightforward and gives good yields via isolation of the DPAH as the ammonium salt. Multinuclear NMR spectroscopy and X-ray structure determination are used for the identification of both the ammonium salt and free acid of the dithiophosphinic derivatives. The DPAH products are stable when exposed to the atmosphere for long periods. In addition, the bis(o-trifluoromethylphenyl)dithiophosphinic acid showed very little degradation when contacted with water and nitric acid for prolonged periods. The most important finding is that bis(o-trifluoromethylphenyl)dithiophosphinic acid selectively extracts trivalent actinides from lanthanides at higher acidities with separation factors of over 125,000 at pH 2.8. Overall, these improvements will help enable the development of advanced reprocessing technologies that allow for complete actinide recycling and minimization of nuclear waste.

John R. Klaehn; Dean R. Peterman; Mason K. Harrup; Richard D. Tillotson; Thomas A. Luther; Jack D. Law; Lee M. Daniels

2008-06-01

174

Role of Ferrocyanides in the Prebiotic Synthesis of ?-Amino Acids  

Science.gov (United States)

We investigated the synthesis of ?-amino acids under possible prebiotic terrestrial conditions in the presence of dissolved iron (II) in a simulated prebiotic ocean. An aerosol-liquid cycle with a prebiotic atmosphere is shown to produce amino acids via Strecker synthesis with relatively high yields. However, in the presence of iron, the HCN was captured in the form of a ferrocyanide, partially inhibiting the formation of amino acids. We showed how HCN captured as Prussian Blue (or another complex compound) may, in turn, have served as the HCN source when exposed to UV radiation, allowing for the sustained production of amino acids in conjunction with the production of oxyhydroxides that precipitate as by-products. We conclude that ferrocyanides and related compounds may have played a significant role as intermediate products in the prebiotic formation of amino acids and oxyhydroxides, such as those that are found in iron-containing soils and that the aerosol cycle of the primitive ocean may have enhanced the yield of the amino acid production.

Ruiz-Bermejo, Marta; Osuna-Esteban, Susana; Zorzano, María-Paz

2013-06-01

175

Coordination polymers of uranium(iv) terephthalates.  

Science.gov (United States)

A series of tetravalent uranium terephthalates has been solvothermally synthesized in the solvent N,N-dimethylformamide (DMF) at temperature 100-150 °C with different water amounts. Composition diagrams have been determined for the U(4+) metallic cation in the presence of terephthalic acid, and their crystal structures revealed the occurrence of two- or three-dimensional coordination polymers. In the absence of water, a mixture of two polytypes T-U2Cl2(bdc)3(DMF)4 () and M-U2Cl2(bdc)3(DMF)4 () has been identified at low temperature (100-110 °C) for bdc/U = 1-4 (bdc = terephthalate linker). Their structures are built up from isolated uranium centers in nine-fold coordination, surrounded by 6 carboxyl oxygen atoms, 2 oxygen atoms coming from DMF molecules and one chlorine atom. The uranium cations are linked to each other through the bdc ligand in order to generate a 3D framework. By increasing the temperature (130-150 °C), a layered like compound has been isolated, U2(bdc)4(DMF)4 (). It is composed of discrete actinide centers in ten-fold coordination, with 8 carboxyl oxygen atoms and 2 oxygen atoms from DMF molecules. The connection of the UO10 units with the bdc linkers generates 2D sheets. When a controlled amount of water is added to the reaction medium, the crystallization of the UiO-66-like U6O4(OH)4(H2O)6(bdc)6·10DMF solid (containing a hexanuclear sub-unit) is observed for temperature 110-120 °C and the H2O/U molar ratio in the range of 2-10. At higher temperature (140-150 °C), a distinct phase appeared, U2O2(bdc)2(DMF) (), which consists of infinite chains of uranium centers, linked to each other via the bdc ligands. Higher water contents led to the formation of urania UO2. PMID:25428593

Falaise, Clément; Assen, Ayalew; Mihalcea, Ionut; Volkringer, Christophe; Mesbah, Adel; Dacheux, Nicolas; Loiseau, Thierry

2015-01-28

176

A New Process for Acrylic Acid Synthesis by Fermentative Process  

Science.gov (United States)

With the synthesis of chemical products through biotechnological processes, it is possible to discover and to explore innumerable routes that can be used to obtain products of high addes value. Each route may have particular advantages in obtaining a desired product, compared with others, especially in terms of yield, productivity, easiness to separate the product, economy, and environmental impact. The purpose of this work is the development of a deterministic model for the biochemical synthesis of acrylic acid in order to explore an alternative process. The model is built-up with the tubular reactor equations together with the kinetic representation based on the structured model. The proposed process makes possible to obtain acrylic acid continuously from the sugar cane fermentation.

Lunelli, B. H.; Duarte, E. R.; de Toledo, E. C. Vasco; Wolf Maciel, M. R.; Maciel Filho, R.

177

UV- and ?-sensitization of latent tracks in polyethylene terephthalate  

International Nuclear Information System (INIS)

Photosensitization of polymer polyethylene terephthalate (PET) bombarded with swift heavy ions (Xe) was studied. Ultraviolet (UV)- and ?-irradiation were used for sensitization. Infrared spectroscopy (IR) and reversed-phase high-performance liquid chromatography (HPLC) were used to study the radiolysis products in latent tracks (directly in the sample or in the etching solution). It was found that the exposure of the sample to ultraviolet light results in the transformation of the radiolysis products formed in the tracks into terephthalic acid. Surface defects, detected by AFM, were found to correspond to tracks; their form (cavities and hillocks) and size changing reflect the changing of latent track state. It was found that UV irradiation destroyed the cross-linked regions in the tracks. This process (photodecomposition) was shown to be the key stage of the UV sensitization and the main cause of etching rate increase. The ?-irradiation effect on track etching was found to be almost the same

178

Fatty acid effects on fibroblast cholesterol synthesis  

International Nuclear Information System (INIS)

Two cell lines of normal (CRL 1475, GM5565) and of familial hypercholesterolemia (FH) (CM 486,488) fibroblasts were preincubated with medium containing the growth factor ITS, 2.5 mg/ml fatty acid-free BSA, or 35.2 ?mol/ml of these fatty acids complexed with 2.5 mg BSA/ml: stearic (18:0), caprylic (8:0), oleic (18:1;9), linoleic (18:2;9,12), linolenic (18:3;9,12,15), docosahexaenoic (22:6;4,7,10,13,16,19)(DHA) or eicosapentaenoic (20:5;5,8,11,14,17)(EPA). After 20 h, cells were incubated for 2 h with 0.2 ?Ci [14C]acetate/ml. Cells were hydrolyzed; an aliquot was quantitated for radioactivity and protein. After saponification and extraction with hexane, radioactivity in the aqueous and organic phases was determined. The FH cells always incorporated 30-90% more acetate/mg protein than normal cells but the pattern of the fatty acid effects was similar in both types. When the values were normalized to 1 for the BSA-only group, cells with ITS had the greatest [14C]acetate incorporation (1.45) followed by the caprylic group (1.14). Cells incubated with 18:3, 20:6 or 22:6 incorporated about the same amount as BSA-only. Those preincubated with 18:2, 18:1, 18:0 showed the least acetate incorporation (0.87, 0.59 and 0.52, respectively). The percentage of total 14C counts which extracted into hexane was much greater in FH cells; however, these values varied with the fatty acid, e.g., 1.31(18:0) and 0.84(8:0) relative to 10) relative to 1

179

Synthesis of the putative structure of 15-oxopuupehenoic acid.  

Science.gov (United States)

Synthesis of the putative structure of the marine natural 15-oxopuupehenoic acid has been achieved starting from commercial (-)-sclareol. Key steps of the synthetic sequence are the Robinson annulation of a ?-ketoester and methyl vinyl ketone and an unprecedented cyclization of the resulting ?,?-enone, which is mediated by tin(IV) chloride in the presence of N-phenylselenophthalimide. The physical properties of the synthetic compound are somewhat different from those reported for the natural product. PMID:25275892

Boulifa, Ettahir; Fernández, Antonio; Alvarez, Esteban; Alvarez-Manzaneda, Ramón; Mansour, Ahmed I; Chahboun, Rachid; Alvarez-Manzaneda, Enrique

2014-11-01

180

Is acetylcarnitine a substrate for fatty acid synthesis in plants  

Energy Technology Data Exchange (ETDEWEB)

Long-chain fatty acid synthesis from [1-[sup 14]C]acetylcarnitine by chloroplasts isolated from spinach (Spinacia oleracea), pea (Pisum sativum), amaranthus (Amaranthus lividus), or maize (Zea mays) occurred at less than 2% of the rate of fatty acid synthesis from [1-[sup 14]C]acetate irrespective of the maturity of the leaves or whether the plastids were purified using sucrose or Percoll medium. [1-[sup 14]C]Acetylcarnitine was not significantly utilized by highly active chloroplasts rapidly prepared from pea and spinach using methods not involving density gradient centrifugation. [1-[sup 14]C]Acetylcarnitine was recovered quantitatively from chloroplast incubations following 10 min in the light. Unlabeled acetyl-L-carnitine (0.4 mM) did not compete with [1-[sup 14]C]acetate (0.2 mM) as a substrate for fatty acid synthesis by any of the more than 70 chloroplast preparations tested in this study. Carnitine acetyltransferase activity was not detected in any chloroplast preparation and was present in whole leaf homogenates at about 0.1% of the level of acetyl-coenzyme A synthetase activity. When supplied to detached pea shoots and detached spinach, amaranthus, and maize leaves via the transpiration stream, 1 to 4% of the [1-[sup 14]C]acetylcarnitine and 47 to 57% of the [1-[sup 14]C]acetate taken up was incorporated into lipids. Most (78--82%) of the [1-[sup 14]C]acetylcarnitine taken up was recovered intact. It is concluded that acetylcarnitine is not a major precursor for fatty acid synthesis in plants. 29 refs., 5 tabs.

Roughan, G. (Horticulture Research Inst., Auckland (New Zealand)); Post-Beittenmiller, D.; Ohlrogge, J. (Michigan State Univ., East Lansing (United States)); Browse, J. (Washington State Univ., Pullman (United States))

1993-04-01

 
 
 
 
181

Synthesis of Bosutinib from 3-Methoxy-4-hydroxybenzoic Acid  

Directory of Open Access Journals (Sweden)

Full Text Available This paper reports a novel synthesis of bosutinib starting from 3-methoxy-4-hydroxybenzoic acid. The process starts with esterification of the starting material, followed by alkylation, nitration, reduction, cyclization, chlorination and two successive amination reactions. The intermediates and target molecule were characterized by 1H-NMR, 13C-NMR, MS and the purities of all the compounds were determined by HPLC.

Xiao Jia Yin

2010-06-01

182

Synthesis of Nanoporous Iminodiacetic Acid Sorbents for Binding Transition Metals  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Iminodiacetic acid (IDAA) forms strong complexes with a wide variety of metal ions. Using self-assembled monolayers in mesoporous supports (SAMMS) to present the IDAA ligand potentially allows for multiple metal-ligand interactions to enhance the metal binding affinity relative to that of randomly oriented polymer-based supports. This manuscript describes the synthesis of a novel nanostructured sorbent material built using self-assembly of a IDAA ligand inside a nanoporous silica, and demonst...

Busche, Brad; Wiacek, Robert; Davidson, Joseph; Koonsiripaiboon, View; Yantasee, Wassana; Addleman, R. Shane; Fryxell, Glen E.

2009-01-01

183

Nordihydroguaiaretic acid analogues: their chemical synthesis and biological activities.  

Science.gov (United States)

Nordihydroguaiaretic acid is a natural occurring lignan mainly isolated and commercially produced from desert plant, creosote bush (Larrea divaricata Cav. Or Corillea tridentate), which can be widely found in the border zone of southern of USA and northern of Mexico. During past 100 years, extensive research has demonstrated that nordihydroguaiaretic acid and its synthetic analogues are potentially useful in treating diseases related to cancers, diabetes, viral, bacterial infections, and inflammation. Remarkably, terameprocol, a tetra-O-methyl derivative of nordihydroguaiaretic acid, is currently in Phase I/II clinical trials as an anticancer agent. This review deals with the chemical synthesis and bioactivities of nordihydroguaiaretic acid and its structurally-related derivatives, which possess anticancer, antioxidant, antimicrobial, anti-inflammatory and immunosuppressive activities. The review consists of the data reported in over 100 publications. PMID:19903157

Chen, Qingqi

2009-01-01

184

Optimized enzymatic synthesis of caffeic acid phenethyl ester by RSM.  

Science.gov (United States)

In this study, optimization of enzymatic synthesis of caffeic acid phenethyl ester (CAPE), catalyzed by immobilized lipase (Novozym 435) from Candida antarctica was investigated. Novozym 435 was used to catalyze caffeic acid and 2-phenylethanol in an isooctane system. Response surface methodology (RSM) and 5-level-4-factor central-composite rotatable design (CCRD) were employed to evaluate the effects of synthesis parameters, such as reaction temperature (30-70 degrees C), reaction time (24-72 hours), substrate molar ratio of caffeic acid to 2-phenylethanol (1:10-1:90) and enzyme amounts (100-500 PLU) on percentage conversion of CAPE by direct esterification. Reaction temperature and time had significant effects on percent conversion. On the basis of ridge max analysis, the optimum conditions for synthesis were: reaction time 59 hours, reaction temperature 69 degrees C, substrate molar ratio 1:72 and enzyme amount 351 PLU. The molar conversion of predicted values and actual experimental values were 91.86+/-5.35% and 91.65+/-0.66%, respectively. PMID:20018263

Chen, Hsiao-Ching; Ju, Hen-Yi; Twu, Yawo-Kuo; Chen, Jiann-Hwa; Chang, Chieh-Ming J; Liu, Yung-Chuan; Chang, Cheng; Shieh, Chwen-Jen

2010-02-28

185

Iminodiacetic acid derivatives of benzimidazole. Synthesis of N-(benzimidazol-2-ylmethyl)iminodiacetic acids  

Energy Technology Data Exchange (ETDEWEB)

Ten new N-(2-benzimidazolylmethyl)iminodiacetic acids (BIMIDA) have been synthesized from the corresponding o-phenylenediamines via intermediate 2-chloromethyl and 2-aminomethyl benzimidazoles as ligands for Tc-99m. Anomalies associated with the synthesis of the iodo-substituted compound are described.

Hunt, F.C.; Wilson, J.G. (Australian Atomic Energy Commission Research Establishment, Lucas Heights. Isotope Div.)

1983-01-01

186

Iminodiacetic acid derivatives of benzimidazole. Synthesis of N-(benzimidazol-2-ylmethyl)iminodiacetic acids  

International Nuclear Information System (INIS)

Ten new N-(2-benzimidazolylmethyl)iminodiacetic acids (BIMIDA) have been synthesized from the corresponding o-phenylenediamines via intermediate 2-chloromethyl and 2-aminomethyl benzimidazoles as ligands for Tc-99m. Anomalies associated with the synthesis of the iodo-substituted compound are described

187

Microbial synthesis of p-hydroxybenzoic acid from glucose.  

Science.gov (United States)

A series of recombinant Escherichia coli strains have been constructed and evaluated for their ability to synthesize p-hydroxybenzoic acid from glucose under fed-batch fermentor conditions. The maximum concentration of p-hydroxybenzoic acid synthesized was 12 g/L and corresponded to a yield of 13% (mol/mol). Synthesis of p-hydroxybenzoic acid began with direction of increased carbon flow into the common pathway of aromatic amino acid biosynthesis. This was accomplished in all constructs with overexpression of a feedback-insensitive isozyme of 3-deoxy-D-arabino-heptulosonic acid 7-phosphate synthase. Expression levels of enzymes in the common pathway of aromatic amino acid biosynthesis were also increased in all constructs to deliver increased carbon flow from the beginning to the end of the common pathway. A previously unreported inhibition of 3-dehydroquinate synthase by L-tyrosine was discovered to be a significant impediment to the flow of carbon through the common pathway. Chorismic acid, the last metabolite of the common pathway, was converted into p-hydroxybenzoic acid by ubiC-encoded chorismate lyase. Constructs differed in the strategy used for overexpression of chorismate lyase and also differed as to whether mutations were present in the host E. coli to inactivate other chorismate-utilizing enzymes. Use of overexpressed chorismate lyase to increase the rate of chorismic acid aromatization was mitigated by attendant decreases in the specific activity of DAHP synthase and feedback inhibition caused by p-hydroxybenzoic acid. The toxicity of p-hydroxybenzoic acid towards E. coli metabolism and growth was also evaluated. PMID:11745165

Barker, J L; Frost, J W

2001-12-01

188

Biphasic effect of oleic acid on hepatic cholesterol synthesis  

International Nuclear Information System (INIS)

The authors observed previously that oleic acid (OA) increased cholesterol (C) synthesis by the perfused liver as well as the activity of HMG-CoA reductase (HMGR) measured at the end of 4 hours. Other workers reported reduction in cholesterogenesis in experiments of shorter duration. To determine whether this effect of OA is biphasic, livers from fed male rats were perfused in vitro with a medium containing OA bound to BSA, glucose, and bovine erythrocytes. During the first hour, incorporation of 3H from 3H2O (23 mCi) into C was lower in the presence of OA (3,295±277 dpm/g) than in its absence (4,969±471 dpm/g), while over the 4 hour interval incorporation was elevated by OA (17,088±2,527 vs 10,278±1,288 dpm/g). Incorporation of 3H into fatty acid, was reduced by OA, the rate of C synthesis was sustained over 4 hours, while in its absence, C synthesis declined between the first and the fourth hour. The acute inhibition of C synthesis by OA does not appear to be due to increased phosphorylation of HMGR, since no difference in the activity of this enzyme (in microsomes prepared and incubated in the presence of 50 mM NaF) was apparent after 1 hour of perfusion (137±24 vs 112±34 pmol/minutes/mg for OA and control groups, respectively). The decline in the rate of C synthesis in the absence of OA was matched by a decline in HMGR activity (54±13 pmol/minute/mg after 4 hours), while in the presence of OA, HMGR activity was suresence of OA, HMGR activity was sustained (126±25 pmol/minute/mg). Total HMGR activity (measured in the absence of NaF) paralleled this change

189

Facile synthesis of glycosylated Fmoc amino acid building blocks assisted by microwave irradiation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The synthesis of glycosylated Fmoc amino acids by reaction of mono- and disaccharide peracetates with Fmoc amino acids having free carboxyl groups was rapidly promoted by Lewis acids (SnCl4, BF3·Et2O) under microwave irradiation. The products are useful building blocks for the synthesis of glycopeptides.

Yao, Nianhuan; Fung, Gabriel; Malken, Hamed; Ye, Long; Lam, Kit S.

2010-01-01

190

Photochemical Synthesis of the Bioconjugate Folic Acid-Gold Nanoparticles  

DEFF Research Database (Denmark)

In this paper we present a rapid and simple onepot method to obtain gold nanoparticles functionalized with folic acid using a photochemistry method. The bioconjugate folic acid-gold nanoparticle was generated in one step using a photo-reduction method, mixing hydrogen tetrachloroaurate with folic acid in different ratios and varying the illumination time of a mercury lamp (?= 255 nm). Scanning electron microscopy showed a particle size of around 40-50nm and dynamic light scattering exhibited that the zeta potential varies from -41 to -50mV with different illumination times. Storage in the dark at 4°C prolongs the stability of folic acid-gold nanoparticle suspensions to up to 26 days. Ultraviolet visible and Fourier transform infrared spectroscopy showed a surface plasmon band of around 534nm and fluorescence spectroscopy exhibited a quenching effect on gold nanoparticles in the fluorescence emission of folic acid and thus confirmed the conjugation of folic acid to the surface of gold nanoparticles. In this study we demonstrate the use of a photochemistry method to obtain folic acid-gold nanoparticles in a simple and rapid way without the use of surfactants and long reaction times. The photochemical synthesis of FA-AuNPs opens new perspectives for creating novel functional nanomaterials for biomedical applications.

León, John Jairo Castillo; Bertel, Linda

2013-01-01

191

76 FR 18519 - Polyethylene Terephthalate Film, Sheet, and Strip From Taiwan: Amended Final Results of...  

Science.gov (United States)

...Administration [A-583-837] Polyethylene Terephthalate Film, Sheet, and Strip...administrative review of polyethylene terephthalate film, sheet, and strip...1\\ See Polyethylene Terephthalate Film, Sheet, and...

2011-04-04

192

77 FR 14493 - Polyethylene Terephthalate Film, Sheet, and Strip From the People's Republic of China: Final...  

Science.gov (United States)

...Administration [A-570-924] Polyethylene Terephthalate Film, Sheet, and Strip...administrative review of polyethylene terephthalate film, sheet, and strip...1\\ See Polyethylene Terephthalate Film, Sheet, and...

2012-03-12

193

21 CFR 870.3470 - Intracardiac patch or pledget made of polypropylene, polyethylene terephthalate, or...  

Science.gov (United States)

...made of polypropylene, polyethylene terephthalate, or polytetrafluoroethylene...made of polypropylene, polyethylene terephthalate, or polytetrafluoroethylene...made of polypropylene, polyethylene terephthalate, or...

2010-04-01

194

Total synthesis of clavicipitic acid and aurantioclavine: stereochemistry of clavicipitic acid revisited.  

Science.gov (United States)

The stereocontrolled total synthesis of clavicipitic acid and aurantioclavine from a common azepino[5,4,3-cd]-indole intermediate is reported. This key azepinoindole nucleus was constructed via a one-pot Heck/Boc-deprotection/aminocyclization process from the 4-iodotryptophan derivative, which was assembled by a Pd-catalyzed indole synthesis procedure. After two or three additional deprotection steps from the azepinoindole intermediates, (-)-trans- and (-)-cis-clavicipitic acid were prepared. The syntheses of both (-)- and (+)-aurantioclavine were achieved with the same azepinoindole intermediates utilizing the Barton decarboxylation reaction as the key step to remove the stereohindered carboxylic acid. During the course of our synthesis, mis-assigned configurations of the synthesized clavicipitic acids and their derivatives in the literature were identified. Extensive studies including 2D-NMR study, X-ray diffraction analysis, titration experiment, and Rf value comparison unambiguously confirmed the new configuration assignment. The trans and cis configuration assignments of the synthesized clavicipitic acids and their derivatives in the past literature should be switched. PMID:20964278

Xu, Zhengren; Hu, Weimin; Liu, Qiang; Zhang, Lihe; Jia, Yanxing

2010-11-19

195

Profiles in garbage: Polyethylene terephthalate  

Energy Technology Data Exchange (ETDEWEB)

Polyethylene terephthalate (PET) is a plastic resin used primarily to make bottles. Soft drinks -- along with salad dressing, fruit juices, peanut butter, and other household and consumer products -- use PET bottles. PET also is used for film, sheeting for cups and food trays, oven-safe trays, and other uses. PET is a relatively new packaging resin, first commercialized in the early 1970s. Because it is an ``engineered`` resin, PET is more expensive than commodity resins such as high-density polyethylene (HDPE) and, for the same reason, it is usually the highest valued plastic recyclable.

Miller, C. [Environmental Industry Associations, Washington, DC (United States)

1997-11-01

196

Exogenous amino acids stimulate net muscle protein synthesis in the elderly.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We have investigated the response of amino acid transport and protein synthesis in healthy elderly individuals (age 71+/-2 yr) to the stimulatory effect of increased amino acid availability. Muscle protein synthesis and breakdown, and amino acid transport were measured in the postabsorptive state and during the intravenous infusion of an amino acid mixture. Muscle-free amino acid kinetics were calculated by means of a three compartment model using data obtained by femoral arterio-venous cathe...

Volpi, E.; Ferrando, A. A.; Yeckel, C. W.; Tipton, K. D.; Wolfe, R. R.

1998-01-01

197

Modificação química de poli(tereftalato de etileno) pós-consumo por reação com ácido sulfúrico: estrutura e propriedades / Chemical modification of post consumer poly(ethylene terephthalate) by sulfuric acid reaction: structure and properties  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese PET pós-consumo foi modificado quimicamente através de reação com ácido sulfúrico por diferentes tempos. O material modificado foi caracterizado por DSC e FTIR-PAS e XPS. Verificou-se que a intensidade relativa do isômero trans diminui enquanto do isômero gauche aumenta para tempos de reação entre 0 [...] e 60 minutos. Após 60 minutos de reação observou-se a presença de endotermas múltiplas que podem ser relacionadas com o desenvolvimento de estruturas intermediárias porque as intensidades relativas dos isômeros trans e gauche não apresentam variação significativa. O valor determinado de capacidade de troca iônica do PET pós-consumo modificado (PETS-pc) é comparável com os valores de resinas ácidas comerciais e não é afetado no intervalo de tempo de reação utilizado. Os valores da capacidade máxima de adsorção, qm, e do parâmetro de afinidade entre o adsorvente e o adsorvato, K, (111,18 ppm e 531,91 mg de corante/100g de adsorvente, respectivamente) para a adsorção do corante Remazol vermelho na amostra quimicamente modificada por 30 minutos foram calculados a partir da isoterma de adsorção de Langmuir. Os resultados indicam que esse material possui características adsorventes, podendo vir a ser utilizado para tratamento de efluente de indústria de tingimento têxtil. Abstract in english Chemical modification of post consumer PET was carried out by reaction with sulfuric acid. The modified material was characterized by DSC, XPS and FTIR-PAS measurements. The relative intensity of trans isomer increases while it decreases for gauche isomer for reaction times from 0 up to 60 min. Afte [...] r 60 minutes of reaction multiple endotherms were observed, which may be related to the development of an intermediated structure, since the relative intensities of the trans and gauche isomers do not change. The ionic exchange capacity of the modified post consumer poly(ethylene terephthalate), PETS-pc, is comparable to commercial acid resins and is not affected by the reaction time. The maximum adsorption capacity, qm, and the affinity parameter, K, (111.18 ppm and 531.91 mg dye/100g adsorvent, respectively) due to the adsorption of Remazol Red were calculated for PET samples chemically modified during 30 minutes from the Langmuir adsorption isotherms. The results indicate that PETS-pc has excellent adsorvent capacity, and can be applied to treatment of textile dye effluents.

Janaína G., Alonso; Elisabeth C., Molina; Edvani C., Muniz; Adley F., Rubira; Gizilene M. de, Carvalho.

2005-03-01

198

Modificação química de poli(tereftalato de etileno pós-consumo por reação com ácido sulfúrico: estrutura e propriedades Chemical modification of post consumer poly(ethylene terephthalate by sulfuric acid reaction: structure and properties  

Directory of Open Access Journals (Sweden)

Full Text Available PET pós-consumo foi modificado quimicamente através de reação com ácido sulfúrico por diferentes tempos. O material modificado foi caracterizado por DSC e FTIR-PAS e XPS. Verificou-se que a intensidade relativa do isômero trans diminui enquanto do isômero gauche aumenta para tempos de reação entre 0 e 60 minutos. Após 60 minutos de reação observou-se a presença de endotermas múltiplas que podem ser relacionadas com o desenvolvimento de estruturas intermediárias porque as intensidades relativas dos isômeros trans e gauche não apresentam variação significativa. O valor determinado de capacidade de troca iônica do PET pós-consumo modificado (PETS-pc é comparável com os valores de resinas ácidas comerciais e não é afetado no intervalo de tempo de reação utilizado. Os valores da capacidade máxima de adsorção, qm, e do parâmetro de afinidade entre o adsorvente e o adsorvato, K, (111,18 ppm e 531,91 mg de corante/100g de adsorvente, respectivamente para a adsorção do corante Remazol vermelho na amostra quimicamente modificada por 30 minutos foram calculados a partir da isoterma de adsorção de Langmuir. Os resultados indicam que esse material possui características adsorventes, podendo vir a ser utilizado para tratamento de efluente de indústria de tingimento têxtil.Chemical modification of post consumer PET was carried out by reaction with sulfuric acid. The modified material was characterized by DSC, XPS and FTIR-PAS measurements. The relative intensity of trans isomer increases while it decreases for gauche isomer for reaction times from 0 up to 60 min. After 60 minutes of reaction multiple endotherms were observed, which may be related to the development of an intermediated structure, since the relative intensities of the trans and gauche isomers do not change. The ionic exchange capacity of the modified post consumer poly(ethylene terephthalate, PETS-pc, is comparable to commercial acid resins and is not affected by the reaction time. The maximum adsorption capacity, qm, and the affinity parameter, K, (111.18 ppm and 531.91 mg dye/100g adsorvent, respectively due to the adsorption of Remazol Red were calculated for PET samples chemically modified during 30 minutes from the Langmuir adsorption isotherms. The results indicate that PETS-pc has excellent adsorvent capacity, and can be applied to treatment of textile dye effluents.

Janaína G. Alonso

2005-03-01

199

A facile synthesis of ethyl 2-acetamido-4-methylenehex-5-enoate, a versatile Diels-Alder synthon for the parallel synthesis of novel alpha-amino acid derivatives  

Digital Repository Infrastructure Vision for European Research (DRIVER)

An efficient synthesis of a diene-containing ?-amino acid via the use of Denmark's coupling reaction and its application to the synthesis of novel ?-amino acid via the Diels-Alder reaction are described. © Georg Thieme Verlag Stuttgart.

Chen, R.; Lee, V.; Adlington, Rm; Baldwin, Je

2007-01-01

200

SYNTHESIS AND SPECTROSCOPIC DIFFERENTIATION OF 2- AND 4-ALKOXYTHIOTETRONIC ACIDS  

Science.gov (United States)

O-Alkylation of thiotetronic acids gives a mixture of 2- and 4-position enol ether products. Comparison of the physical data revealed that UV spectroscopy was the most reliable method of distinguishing between these related ethers. We have determined that 4-position ethers have a distinct absorption between 235–240 nm, while 2-position ethers have two absorbance peaks, one between 205–220 nm and the other between 305–310 nm. This report describes the synthesis and unambiguous characterization of 2- and 4-methoxy-3,5-dimethylthiotetronic acids. The UV absorption properties of several other pairs of thiotetronic acid ethers confirm that these differences are general features that provide a simple method for distinguishing between 2- and 4-substituted isomers. PMID:16733529

Shenoy, Gautham; Kim, Pilho; Goodwin, Michael; Nguyen, Quynh-Anh; Barry, Clifton E.; Dowd*, Cynthia S.

2006-01-01

 
 
 
 
201

Synthesis and characterization of magnetite nanoparticles coated with lauric acid  

Energy Technology Data Exchange (ETDEWEB)

Understanding the process of synthesis of magnetic nanoparticles is important for its implementation in in vitro and in vivo studies. In this work we report the synthesis of magnetic nanoparticles made from ferrous oxide through coprecipitation chemical process. The nanostructured material was coated with lauric acid and dispersed in aqueous medium containing surfactant that yielded a stable colloidal suspension. The characterization of magnetic nanoparticles with distinct physico-chemical configurations is fundamental for biomedical applications. Therefore magnetic nanoparticles were characterized in terms of their morphology by means of TEM and DLS, which showed a polydispersed set of spherical nanoparticles (average diameter of ca. 9 nm) as a result of the protocol. The structural properties were characterized by using X-ray diffraction (XRD). XRD pattern showed the presence of peaks corresponding to the spinel phase of magnetite (Fe{sub 3}O{sub 4}). The relaxivities r{sub 2} and r{sub 2}* values were determined from the transverse relaxation times T{sub 2} and T{sub 2}* at 3 T. Magnetic characterization was performed using SQUID and FMR, which evidenced the superparamagnetic properties of the nanoparticles. Thermal characterization using DSC showed exothermic events associated with the oxidation of magnetite to maghemite. - Highlights: • Synthesis of magnetic nanoparticles coated with lauric acid • Characterization of magnetic nanoparticles • Morphological, structural, magnetic, calorimetric and relaxometric characterization.

Mamani, J.B., E-mail: javierbm@einstein.br [Instituto do Cérebro-InCe, Hospital Israelita Albert Einstein-HIAE, 05651-901 São Paulo (Brazil); Costa-Filho, A.J. [Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto (Brazil); Cornejo, D.R. [Instituto de Física Universidade de São Paulo, USP, São Paulo (Brazil); Vieira, E.D. [Instituto de Física, Universidade Federal de Goiás, Goiânia (Brazil); Gamarra, L.F. [Instituto do Cérebro-InCe, Hospital Israelita Albert Einstein-HIAE, 05651-901 São Paulo (Brazil)

2013-07-15

202

Terephthalate salts of dipositive cations.  

Science.gov (United States)

The crystal structures of M(C(8)H(4)O(4))(H(2)O)(2), M = Mg, Mn, Fe and Co, have been determined by applying Monte Carlo simulated annealing techniques to synchrotron powder diffraction data and refined by the Rietveld method using both synchrotron and laboratory powder data. These isostructural compounds crystallize in the monoclinic space group C2/c, with 18.2734 (9) CASTEP) were used to determine the H-atom positions and analyze the hydrogen bonding and the metal coordination. Both the atomic charges and the M-O bond-overlap populations indicate that, despite the fact that these compounds are isostructural, the metal-terephthalate bonding is different. The bonding in the Mg complex is essentially ionic, while the M-O bonds in the Mn, Fe and Co complexes have significant covalent character. Comparison of a new Rietveld refinement of the structure of copper(II) terephthalate trihydrate with the reported single-crystal structure provides an opportunity to assess the accuracy and precision that can be expected from structures of aromatic carboxylates determined using X-ray powder data. The average difference between the bond distances in the two structures is 0.03 A and the average difference in bond angles is only 1.1 degrees. PMID:12324694

Kaduk, James A

2002-10-01

203

[Synthesis of new mandelic acid derivatives with preservative action. Synthesis and acute toxicity study].  

Science.gov (United States)

Starting from the antiseptic action of DL mandelic acid, there were synthesized a series of esters of the mandelic acid, esters which could have preservative action. This study present the synthesis, structure validation and the acute toxicity study, for the new synthesized compounds. The esters were obtained by acylating 4-hydroxybenzoic acid propyl, ethyl, methyl esters and salicylic acid with the DL mandelic chloride (that was protected initially by the hydroxylic group). The structure of the synthesized compounds was confirmed by quantitative elemental analysis and RMN 1H spectral measurements. The acute toxicity was determined for two of the esters, who proved to had a preservative action (previously studied) and indicated that these esters have a small toxicity. PMID:15688782

Stan, C?t?lina; N?stase, V; Pavelescu, M; Vasile, Cornelia; Dumitrache, M; Gherase, Floren?a; N?stas?, Veronica

2004-01-01

204

Synthesis and characterization of copolyanhydrides of carbohydrate-based galactaric acid and adipic acid.  

Science.gov (United States)

A series of copolyanhydrides, consisting of 2,3,4,5-tetra-O-acetylgalactaric acid (AGA) and adipic acid (AA) as monomer units, was polymerized. Synthesis of AGA monomer consisted of two steps. First, O-acetylation of galactaric acid secondary hydroxyl groups was performed using acetic anhydride as a reagent. Acetic anhydride was then further used as a reagent in the synthesis of diacetyl mixed anhydride of AGA. Polymerizations were conducted as bulk condensation polymerization at 150°C. Thermal properties of the copolymers varied depending on monomer composition. Increase in the AGA content had a clear increasing effect on the Tg. A similar increasing effect was observed in Tm. The degree of crystallinity decreased as AGA content increased. There was a slightly lowering tendency in the molecular weights of the obtained polymers when the AGA content in the polymerization mixtures increased. The described synthesis route shows that bio-based aldaric acid monomers are potential candidates for the adjustment of thermal properties of polyanhydrides. PMID:25497340

Mehtiö, Tuomas; Nurmi, Leena; Rämö, Virpi; Mikkonen, Hannu; Harlin, Ali

2015-01-30

205

Synthesis of [11C-methyl]-?-aminoisobutyric acid (AIB)  

International Nuclear Information System (INIS)

Alpha-aminoisobutyric acid (AIB) labeled with the cyclotron-produced, positron-emitting radionuclide 11C has been synthesized with the label in the alpha-methyl group. Our previously published synthesis of [11C] AIB in the carboxyl position from [11C] HCN requires a rigorous quality assurance program to ensure that the concentration of cyanide in the final product is below certain levels. This can be avoided using the method described here with [11C] CH3. The radiochemical yield calculated to end of bombardment (EOB) was 45-55% from [11C] CO2 with radiochemical purity of [11C-methyl] AIB exceeding 99%. Synthesis times from [11C] CO2 were about 55 min. Specific activities of 1 Ci/?mol were achieved on average. It has been shown that [11C-carboxyl] AIB is a useful imaging agent in patients with soft tissue cancers and melanoma, and it demonstrates tumor uptake in a spectrum of other animal tumor models. Because AIB is a nonmetabolized amino acid, [11C-methyl] AIB should be equally as useful. Either agent can be employed for the quantification of the A-type amino acid transport system in vivo with PET

206

Effects of ethanol and pantothenic acid on brain acetylcholine synthesis.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

1. Measurements of brain acetylcholine (ACh) synthesis from precursor [14C]-pyruvate, pantothenic acid (PA) concentration in the brain, and blood ethanol (EtOH) concentration were made in rats treated with either ethanol (5-6 g kg-1 body wt daily) alone or ethanol with PA supplementation (100-200 mg kg-1 body wt daily). EtOH with or without PA was administered orally by either Lieber-Decarli liquid diet for 4 weeks and 4 months or by oral intubation for 1 and 4 days. Matched controls were giv...

Rivera-calimlim, L.; Hartley, D.; Osterhout, D.

1988-01-01

207

Synthesis of Nanoporous Iminodiacetic Acid Sorbents for Binding Transition Metals  

Energy Technology Data Exchange (ETDEWEB)

Iminodiacetic acid (IDAA) forms strong complexes with a wide variety of metal ions. Using self-assembled monolayers in mesoporous supports (SAMMS) to present the IDAA ligand allows for multiple metal-ligand interactions to enhance the metal binding affinity relative to that of randomly oriented polymer-based supports. This manuscript describes the synthesis of a novel nanostructured sorbent material built using self-assembly of a IDAA ligand inside a nanoporous silica, and demonstrates its use for capturing transition metal cations, and anionic metal complexes, such as PdCl4-2.

Busche, Brad J.; Wiacek, Robert J.; Davidson, Joseph D.; Koonsiripaiboon, View; Yantasee, Wassana; Addleman, Raymond S.; Fryxell, Glen E.

2009-04-01

208

Synthesis of Nanoporous Iminodiacetic Acid Sorbents for Binding Transition Metals  

Science.gov (United States)

Iminodiacetic acid (IDAA) forms strong complexes with a wide variety of metal ions. Using self-assembled monolayers in mesoporous supports (SAMMS) to present the IDAA ligand potentially allows for multiple metal-ligand interactions to enhance the metal binding affinity relative to that of randomly oriented polymer-based supports. This manuscript describes the synthesis of a novel nanostructured sorbent material built using self-assembly of a IDAA ligand inside a nanoporous silica, and demonstrates its use for capturing transition metal cations, and anionic metal complexes, such as PdCl4?2. PMID:22068901

Busche, Brad; Wiacek, Robert; Davidson, Joseph; Koonsiripaiboon, View; Yantasee, Wassana; Addleman, R. Shane; Fryxell, Glen E.

2009-01-01

209

Optimization of Butylphosphate synthesis from O-Phosphoric Acid  

International Nuclear Information System (INIS)

This work was carried out in order to confirm results of previous work and to enhance the yield of TBP synthesis. This, many reactions have been realised under differents experimental condition (temperature, acid/ alcool molar ratio, pressure and the quantity of promoter agent 'POCL3'). the TBP yield variations as function the experimental parameters, has been expressed, using the 2n factorial plan mathematical model. The experimental results were compared to those given by the theoritical model, and the optimal conditions were then drawn out

210

Lewis Acidic Ionic Liquids As New Addition Catalyst For Oleic Acid To Monoestolide Synthesis  

Directory of Open Access Journals (Sweden)

Full Text Available Estolide compound has a large potential in many industrial applications such as biodegradable lubricants and in cosmetic formulation. In this study, monoestolide can be prepared by addition reaction of oleic acid under vacuum-reflux and solvent free condition for 10 hours at 85 °C in the presence of solid zinc chloride anhydrous (ZnCl2, choline chloride (ChCl and ionic liquids (IL ChCl-ZnCl2, ChCl-FeCl3, ChCl-SnCl2, ChCl-CuCl2 as homogenous acid catalysts. These reactions were compared with common homogenous catalyst namely sulfuric acid (H2SO4. The FTIR analysis show that addition reaction using the above catalysts showed the presence of three new peaks at 1732 cm-1 for C=O ester, 967.0 cm-1 for trans-CH=CH and 1176 cm-1 for C-O-C which confirmed the existence of monoestolide. The LC-MS results showed peak for the present of new monoestolides at retention time (tR 12.3 min corresponding to m/z 563.48. Among the IL, ChCl-ZnCl2 surprisingly exhibited higher activity which is 98 % acid oleic conversion and 80 % selective for the synthesis of monoestolides. As a result, this IL gave two potential functions as a solvent as well as a green catalyst for monoestolide synthesis from oleic acid.

Nadia Farhana Adnan

2011-09-01

211

Lipase catalyzed synthesis of organic acid esters of lactic acid in non-aqueous media.  

Science.gov (United States)

Lipases from Rhizomucor miehei (Lipozyme IM20) and porcine pancreas (PPL) were employed as catalysts for the esterification reaction between the hydroxyl group of lactic acid and the carboxyl group of organic acids. Reactions were carried out at both shake-flask and bench-scale levels. Various parameters, such as solvent, temperature, substrate and enzyme concentrations, effect of buffer volume, buffer pH and water volume, were investigated for optimization of yields. While ethylmethyl ketone (EMK) was found to be the best solvent for shake-flask reactions, chloroform gave higher yields at bench-scale level. Detailed studies were carried out with respect to the synthesis of palmitoyl and stearoyl lactic acids. At shake-flask level, maximum yields of 37.5 and 40% were observed in case of palmitoyl and stearoyl lactic acids, respectively, with Lipozyme IM20; at bench-scale level, the maximum yields were 85.1 and 99% respectively, when PPL was employed. Of all the organic acids employed (C(2)--C(18)), only lauric, palmitic and stearic acids gave yields above 50%. At bench-scale level, PPL could be reused for up to three cycles with yields above 40%. Esters prepared were found to conform to Food Chemical Codex (FCC) specifications in terms of acid value, ester value, sodium and lactic acid contents. PMID:11278035

Kiran, K R; Divakar, S

2001-05-01

212

Tetramethylammonium hemi(terephthalate dihydrate  

Directory of Open Access Journals (Sweden)

Full Text Available In the title compound, (CH34N+·0.5C8H4O42?·2H2O, the complete terephthalate dianion is completed by twofold symmetry and has a dihedral angle of 23.5?(2° between the carboxylate group and its parent ring. Two independent water molecules serve as both donors and acceptor in the construction of undulating hydrogen-bonded host layers with various O—H...O contacts ocurring between the anion and two water molecules. At the same time, the tetramethylammonium cations, as the sphere-like guest species, are arranged in two rows between neighboring host layers, with an approximate interlayer distance of 7.36?Å, forming a sandwich-like crystal structure.

Yunxia Yang

2011-07-01

213

A facile synthesis of 14C labelled pyruvic acid, suitable for 11C labelling  

International Nuclear Information System (INIS)

A simple pyrolytic procedure is described which is useful for the preparation of carbon-14 labelled pyruvic acid using labelled glyceric acid. The method is also suitable when the synthesis time needs to be short as for the synthesis with 11C isotope. (author)

214

Biodegradation of dimethyl terephthalate by Pasteurella multocida Sa follows an alternative biochemical pathway.  

Science.gov (United States)

Pasteurella multocida Sa, a bacterial strain isolated from mangrove sediment by enrichment technique, was capable of transforming dimethyl terephthalate (DMT). Biodegradation of DMT was shown to take place as a series of sequential steps involving the hydrolysis of two ester linkages between the carboxyl groups of the terephthalate and the methyl side-chain initially to produce mono-methyl terephthalate (MMT) and then terephthalic acid (TA), respectively. However, with ethanol as the carrying solvent, there was a formation of one metabolite previously not observed. The two metabolites were characterized by high performance-liquid chromatography-electron ionization mass spectrometry as MMT and mono-ethyl terephthalate (MET), suggesting the existence of an alternative biochemical pathway in the degradation of DMT by P. multocida Sa. Since the presence of MMT and ethanol in culture inoculated with P. multocida Sa was prerequisites for the formation of MET, biologically mediated trans-esterification was proposed as a mechanism for the novel biochemical process observed. PMID:16676217

Li, Jiaxi; Gu, Ji-Dong

2006-05-01

215

77 FR 46704 - Polyethylene Terephthalate Film, Sheet, and Strip From Taiwan: Preliminary Results of Antidumping...  

Science.gov (United States)

...attributable to the price volatility for purified terephthalic acid (PTA) and mono ethylene glycol (MEG),\\37\\ the main inputs consumed...to both Shinkong and Nan Ya. Thus, we used quarterly average PTA and EG costs and annual weighted-average fabrication...

2012-08-06

216

Synthesis and scavenging role of furan fatty acids.  

Science.gov (United States)

Fatty acids play important functional and protective roles in living systems. This paper reports on the synthesis of a previously unidentified 19 carbon furan-containing fatty acid, 10,13-epoxy-11-methyl-octadecadienoate (9-(3-methyl-5-pentylfuran-2-yl)nonanoic acid) (19Fu-FA), in phospholipids from Rhodobacter sphaeroides. We show that 19Fu-FA accumulation is increased in cells containing mutations that increase the transcriptional response of this bacterium to singlet oxygen ((1)O2), a reactive oxygen species generated by energy transfer from one or more light-excited donors to molecular oxygen. We identify a previously undescribed class of S-adenosylmethionine-dependent methylases that convert a phospholipid 18 carbon cis unsaturated fatty acyl chain to a 19 carbon methylated trans unsaturated fatty acyl chain (19M-UFA). We also identify genes required for the O2-dependent conversion of this 19M-UFA to 19Fu-FA. Finally, we show that the presence of (1)O2 leads to turnover of 19Fu-Fa in vivo. We propose that furan-containing fatty acids like 19Fu-FA can act as a membrane-bound scavenger of (1)O2, which is naturally produced by integral membrane enzymes of the R. sphaeroides photosynthetic apparatus. PMID:25092314

Lemke, Rachelle A S; Peterson, Amelia C; Ziegelhoffer, Eva C; Westphall, Michael S; Tjellström, Henrik; Coon, Joshua J; Donohue, Timothy J

2014-08-19

217

Role for deoxyribonucleic acid ligase in deoxyribonucleic acid polymerase I-dependent repair synthesis in toluene-treated Escherichia coli  

International Nuclear Information System (INIS)

In a toluene-treated mutant of Escherichia coli K-12 having a temperature-sensitive, conditionally lethal mutation in the structural gene for deoxyribonucleic acid (DNA) ligase, an extensive DNA repair synthesis occurred in x-irradiated cells at the nonpermissive temperature, 420C. At the permissive temperature, 300C, nearly normal semiconservative synthesis and limited repair synthesis were observed when DNA ligase was activated by the addition of nicotinamide adenine dinucleotide

218

Regulation of bile acid synthesis in rat hepatocyte monolayer cultures  

International Nuclear Information System (INIS)

Primary hepatocyte monolayer cultures (PHC) were prepared and incubated in serum free media. Cells from a cholestyramine fed rat converted exogenous [14C]-cholesterol into [14C]-bile acids at a 3-fold greater rate than rats fed a normal diet. PHC synthesize bile acids (BA) at a rate of approximately 0.06 ?g/mg protein/h. The major bile acid composition, as determined by GLC, was ?-muricholic acid (BMC) and cholic acid (CA) in a 3:1 ratio, respectively. PHC rapidly converted free BA and BA intermediates into taurine conjugated trihydroxy-BA up to 87h after plating. 3-Hydroxy-3-methylglutaryl-coenzyme A-reductase activity assayed in microsomes prepared from PHC, decreased during the initial 48h, then remained constant. Cholesterol 7?-hydroxylase activity decreased during the initial 48h, then increased during the next 48h. This occurred while whole cells produced BA at a linear rate. The effect of individual BA on bile acid synthesis (BAS) was also studied. Relative rates of BAS were measured as the conversion of [14C]-cholesterol into [14C]-BA. BA combinations were tested in order to simulate the composition of the enterohepatic circulation. The addition of TCA (525 ?M) plus TCDCA (80?M), in concentrations which greatly exceed the concentration of BA (60?M) in rate portal blood, failed to inhibit BAS. BA plus phospholipid and/or cholesterol also did not inhibit BAS. Surprisingly, crude rat bile with a final concentratioe rat bile with a final concentration comparable to those in the synthetic mix inhibited [14C]-cholesterol conversion into [14C]-BA

219

Synthesis under Microwave Irradiation, Characterization and Application of Alkyliminodimethylenediphosphonic Acids in Solvent Extraction of Iron (III)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The synthesis under microwave irradiation, characterization and application of new alkyliminodimethylenediphosphonic acids in solvent extraction of iron (III) has been investigated. The alkyliminodimethylenediphosphonic acids synthesized were: hexadecyliminodimethylenediphosphonic acid (HIDMP, H4L1) and decyliminodimethylenediphosphonic acid (DIDMP, H4L2). After purification, these products were charac...

Bouhoun Ali, M.; Badjah Hadj Ahmed, A. Y.; Attou, M.; Elias, A. H.; Didi, M. A.

2011-01-01

220

Synthesis under Microwave Irradiation, Characterization and Application of Alkyliminodimethylenediphosphonic Acids in Solvent Extraction of Uranium (VI)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The synthesis under microwave irradiation, characterization and application of new alkyliminodimethylenediphosphonic acids in solvent extraction of uranium (VI) have been investigated. The alkyliminodimethylenediphosphonic acids synthesized were: hexadecyliminodimethylenediphosphonic acid (HIDMP, H4L1) and decyliminodimethylenediphosphonic acid (DIDMP, H4L2). After purification, these products were cha...

Bouhoun Ali, M.; Badjah Hadj Ahmed, A. Y.; Attou, M.; Elias, A.; Didi, M. A.

2011-01-01

 
 
 
 
221

ETBE synthesis over silicotungstic acid and tungstophosphoric acid catalysts calcined at different temperatures  

Energy Technology Data Exchange (ETDEWEB)

Vapor phase ethyl tertiary butyl ether synthesis was investigated using heat treated heteropoly acid catalysts, namely silicotungtsic acid (STA) and tungstophosphoric acid-Keggin (TPA-K) and these results were compared with the results obtained with untreated catalysts. ETBE synthesis experiments showed that heat treatment of TPA-K at temperatures over 473 K had caused significant decrease of its catalytic activity. Activity of STA was more stable and deactivation of this catalyst was observed by heat treatment at 673 K and above. Heat treatment at high temperatures caused loss of constitutional water of STA and TPA-K, causing loss of protons, consequently the loss of acidity of the catalysts, resulting deactivation. FT-IR, TGA-DTA and DRIFTS analyses on pyridine-adsorbed catalysts supported the conclusions related to structural changes of STA and TPA-K with heat treatment. Highest ETBE yields were obtained at around 368 K, while at temperatures over 423 K formation of DEE and ethylene were observed due to dehydration of ethanol. (author)

Degirmenci, Levent; Oktar, Nuray; Dogu, Gulsen [Department of Chemical Engineering, Gazi University, 06570 Maltepe, Ankara (Turkey)

2010-07-15

222

Expression of fatty acid synthesis genes and fatty acid accumulation in haematococcus pluvialis under different stressors  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Biofuel has been the focus of intensive global research over the past few years. The development of 4th generation biofuel production (algae-to-biofuels based on metabolic engineering of algae is still in its infancy, one of the main barriers is our lacking of understanding of microalgal growth, metabolism and biofuel production. Although fatty acid (FA biosynthesis pathway genes have been all cloned and biosynthesis pathway was built up in some higher plants, the molecular mechanism for its regulation in microalgae is far away from elucidation. Results We cloned main key genes for FA biosynthesis in Haematococcus pluvialis, a green microalga as a potential biodiesel feedstock, and investigated the correlations between their expression alternation and FA composition and content detected by GC-MS under different stress treatments, such as nitrogen depletion, salinity, high or low temperature. Our results showed that high temperature, high salinity, and nitrogen depletion treatments played significant roles in promoting microalgal FA synthesis, while FA qualities were not changed much. Correlation analysis showed that acyl carrier protein (ACP, 3-ketoacyl-ACP-synthase (KAS, and acyl-ACP thioesterase (FATA gene expression had significant correlations with monounsaturated FA (MUFA synthesis and polyunsaturated FA (PUFA synthesis. Conclusions We proposed that ACP, KAS, and FATA in H. pluvialis may play an important role in FA synthesis and may be rate limiting genes, which probably could be modified for the further study of metabolic engineering to improve microalgal biofuel quality and production.

Lei Anping

2012-03-01

223

Injury-induced inhibition of small intestinal protein and nucleic acid synthesis  

Energy Technology Data Exchange (ETDEWEB)

Small intestinal mucosal weight and nutrient absorption are significantly diminished early after cutaneous thermal injuries. Because these intestinal properties are highly dependent on rates of nucleic acid and protein synthesis, in vivo incorporation of thymidine, uridine, and leucine into small intestinal deoxyribonucleic acid, ribonucleic acid, and proteins were measured. Deoxyribonucleic acid synthesis was markedly decreased with the lowest thymidine incorporation in the jejunum (p less than 0.01); these findings were confirmed by autoradiographic identification of radiolabeled nuclei in the intestinal crypts. Protein synthesis was decreased by 6 h postinjury (p less than 0.01) but had returned to normal by 48 h. Consistent with a decreased rate of protein synthesis, ribonucleic acid synthesis was also decreased 18 h postinjury (p less than 0.01). These decreased deoxyribonucleic acid, ribonucleic acid, and protein synthesis rates are not likely a result of ischemia because in other studies of this injury model, intestinal blood flow was not significantly changed by the burn injury. Potentially, factors initiating the acute inflammatory reaction may directly inhibit nucleic acid and protein synthesis and lead to alterations in nutrient absorption and intestinal barrier function after injury.

Carter, E.A.; Hatz, R.A.; Yarmush, M.L.; Tompkins, R.G. (Massachusetts General Hospital, Boston (USA))

1990-06-01

224

Injury-induced inhibition of small intestinal protein and nucleic acid synthesis  

International Nuclear Information System (INIS)

Small intestinal mucosal weight and nutrient absorption are significantly diminished early after cutaneous thermal injuries. Because these intestinal properties are highly dependent on rates of nucleic acid and protein synthesis, in vivo incorporation of thymidine, uridine, and leucine into small intestinal deoxyribonucleic acid, ribonucleic acid, and proteins were measured. Deoxyribonucleic acid synthesis was markedly decreased with the lowest thymidine incorporation in the jejunum (p less than 0.01); these findings were confirmed by autoradiographic identification of radiolabeled nuclei in the intestinal crypts. Protein synthesis was decreased by 6 h postinjury (p less than 0.01) but had returned to normal by 48 h. Consistent with a decreased rate of protein synthesis, ribonucleic acid synthesis was also decreased 18 h postinjury (p less than 0.01). These decreased deoxyribonucleic acid, ribonucleic acid, and protein synthesis rates are not likely a result of ischemia because in other studies of this injury model, intestinal blood flow was not significantly changed by the burn injury. Potentially, factors initiating the acute inflammatory reaction may directly inhibit nucleic acid and protein synthesis and lead to alterations in nutrient absorption and intestinal barrier function after injury

225

Synthesis of esters of 3 A, 7 A, 12 A-three ketocholanic acid  

International Nuclear Information System (INIS)

The synthesis of esters of 3 A, 7 A, 12 A-three ketocholanic acid was carried out. Their structure and purity were defined by means of infrared-spectroscopy and gas chromatography. The initial 3 A, 7 A, 12 A-three ketocholanic acid was the object of investigation. Methyl, ethyl, propyl, isopropyl, and butyl alcohols were used for synthesis of esters of 3 A, 7 A, 12 A-three ketocholanic acid.

226

Synthesis of 13C—O-labelled tertiary alkanoic acids by the Koch-haaf-reaction  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Good yields of tertiary alkanoic acids are obtained from the Koch-Haaf-synthesis even when only stoichiometric amounts of carbinol and HCOOH are used. This offers a new approach to 13CO-labelled tertiary alkanoic acids. - An excess of HCOOH is generally used in the Koch-Haaf-synthesis1) of carboxylic acids from carbinols and HCOOH in conc. H2SO4.

Langhals, Heinz; Mergelsberg, Ingrid; Ru?chardt, Christoph

1981-01-01

227

Kinetic resolution and stereoselective synthesis of 3-substituted aspartic acids by using engineered methylaspartate ammonia lyases.  

Science.gov (United States)

Enzymatic amino acid synthesis: Kinetic resolution and asymmetric synthesis of various valuable 3-substituted aspartic acids, which were obtained in fair to good yields with diastereomeric ratio values of up to >98:2 and enantiomeric excess values of up to >99?%, by using engineered methylaspartate ammonia lyases are described. These biocatalytic methodologies for the selective preparation of aspartic acid derivatives appear to be attractive alternatives for existing chemical methods. PMID:23852946

Raj, Hans; Szymanski, Wiktor; de Villiers, Jandré; Puthan Veetil, Vinod; Quax, Wim J; Shimamoto, Keiko; Janssen, Dick B; Feringa, Ben L; Poelarends, Gerrit J

2013-08-19

228

76 FR 8770 - Polyethylene Terephthalate (Pet) Film From Korea  

Science.gov (United States)

...Investigation No. 731-TA-459 (Third Review)] Polyethylene Terephthalate (Pet) Film From Korea AGENCY: United States...review concerning the antidumping duty order on polyethylene terephthalate (PET) film from...

2011-02-15

229

Induction of fatty acid synthesis is a key requirement for phagocytic differentiation of human monocytes.  

Science.gov (United States)

Monocytes are precursors of macrophages. Here we demonstrate that macrophage colony-stimulating factor (M-CSF)-dependent differentiation of primary human monocytes from healthy volunteers induces transcription of SREBP-1c target genes required for fatty acid (FA) biosynthesis and impairs transcription of SREBP-2 target genes required for cholesterol synthesis. Detailed lipid metabolic profiling showed that this transcriptional regulation leads to a dramatically increased fatty acid synthesis as driving force for enhanced phospholipid synthesis. During cell differentiation the major lipid class switches from cholesterol in monocytes to phosphatidylcholine in macrophages. Ultrastructural analysis revealed that this transcriptional and metabolic regulation is essential for development of macrophage filopodia and cellular organelles including primary lysosomes, endoplasmic reticulum, and Golgi network. Additional functional studies showed that suppression of fatty acid synthesis prevents phagocytosis representing a central macrophage function. Therefore induction of fatty acid synthesis is a key requirement for phagocyte development and function. PMID:20385828

Ecker, Josef; Liebisch, Gerhard; Englmaier, Marion; Grandl, Margot; Robenek, Horst; Schmitz, Gerd

2010-04-27

230

Indoleacetic Acid and the synthesis of glucanases and pectic enzymes.  

Science.gov (United States)

Indoleacetic acid (IAA) and/or inhibitors of DNA, RNA or protein synthesis were added to the apex of decapitated seedlings of Pisum sativum L. var. Alaska. At various times up to 4 days, enzymic protein was extracted from a segment of epicotyl immediately below the apex and assayed for its ability to hydrolyse polysaccharides or their derivatives. With the exception of amylase, the total amounts per segment of all of the tested enzymes increased due to IAA treatment. The development of beta-1,4-glucanase (cellulase) activity per unit of protein or fresh weight proceeded according to a typical sigmoid induction curve. Pectinase was formed for about 2 days in control segments and IAA treatment resulted in continued synthesis for at least another 2 days provided cell division took place. beta-1,3-glucanase and pectinesterase activities were only enhanced by IAA to the extent that total protein levels increased. Reaction mechanisms for these effects and functions for the enzymes during growth are discussed. PMID:16656834

Datko, A H; Maclachlan, G A

1968-05-01

231

Total Synthesis of Five Lipoteichoic acids of Clostridium difficile  

DEFF Research Database (Denmark)

The emergence of hypervirulent resistant strains have made Clostridium difficile a notorious nosocomial pathogen and has resulted in a renewed interest in preventive strategies, such as vaccines based on (synthetic) cell wall antigens. Recently, the structure of the lipoteichoic acid (LTA) of this species has been elucidated. Additionally, this LTA was found to induce the formation of protective antibodies against C. difficile in rabbits and mice. The LTA from C. difficile is isolated as a microheterogenous mixture, differing in size and composition, impeding any structure-activity relationship studies. To ensure reliable biological results, pure and well-defined synthetic samples are required. In this work the total synthesis of LTAs from C. difficile with defined chain length is described and the initial biological results are presented.

Hogendorf, Wouter Frederik Johan; Gisch, Nicolas

2014-01-01

232

Enzymatic synthesis and application of fatty acid ascorbyl esters  

Directory of Open Access Journals (Sweden)

Full Text Available Fatty acid ascorbyl esters are liposoluble substances that possess good antioxidative properties. These compounds could be synthesized by using various acyl donors for acylation of vitamin C in reaction catalyzed by chemical means or lipases. Enzymatic process is preferred since it is regioselective, performed under mild reaction conditions, with the obtained product being environmentally friendly. Polar organic solvents, ionic liquids, and supercritical fluids has been successfully used as a reaction medium, since commonly used solvents with high Log P values are inapplicable due to ascorbic acid high polarity. Acylation of vitamin C using fatty acids, their methyl-, ethyl-, and vinyl esters, as well as triglycerides has been performed, whereas application of the activated acyl donors enabled higher molar conversions. In each case, majority of authors reported that using excessive amount of the acyl donor had positive effect on yield of product. Furthermore, several strategies have been employed for shifting the equilibrium towards the product by water content control. These include adjusting the initial water activity by pre-equilibration of reaction mixture, enzyme preparation with water vapor of saturated salt solutions, and the removal of formed water by the addition of molecular sieves or salt hydrate pairs. The aim of this article is to provide a brief overview of the procedures described so far for the lipase-catalyzed synthesis of fatty acid ascorbyl esters with emphasis on the potential application in food, cosmetics, and pharmaceutics. Furthermore, it has been pointed out that the main obstacles for process commercialization are long reaction times, lack of adequate purification methods, and high costs of lipases. Thus, future challenges in this area are testing new catalysts, developing continuous processes for esters production, finding cheaper acyl donors and reaction mediums, as well as identifying standard procedures for purification of products which will not require consumption of large amounts of non-biocompatible organic solvents.

Stojanovi? Marija M.

2013-01-01

233

Role of Fatty-acid Synthesis in Dendritic Cell Generation and Function  

Science.gov (United States)

Dendritic cells (DC) are professional antigen presenting cells that regulate innate and adaptive immunity. The role of fatty-acid synthesis in DC development and function is uncertain. We found that blockade of fatty-acid synthesis markedly decreases dendropoiesis in the liver and in primary and secondary lymphoid organs in mice. Human DC development from PBMC precursors was also diminished by blockade of fatty-acid synthesis. This was associated with higher rates of apoptosis in precursor cells and increased expression of Cleaved Caspase 3 and BCL-xL, and down-regulation of Cyclin B1. Further, blockade of fatty-acid synthesis decreased DC expression of MHCII, ICAM-1, B7-1, B7-2 but increased their production of selected pro-inflammatory cytokines including IL-12 and MCP-1. Accordingly, inhibition of fatty-acid synthesis enhanced DC capacityto activate allogeneic as well as antigen-restricted CD4+ and CD8+ T cells and induce CTL responses. Further, blockade of fatty-acid synthesis increased DC expression of Notch ligands and enhanced their ability to activate NK cell immune-phenotype and IFN-? production. Since endoplasmic reticular (ER)-stress can augment the immunogenic function of APC, we postulated that this may account for the higher DC immunogenicity. We found that inhibition of fatty-acid synthesis resulted in elevated expression of numerous markers of ER stress in humans and mice and was associated with increased MAP kinase and Akt signaling. Further, lowering ER-stress by 4-phenylbutyrate mitigated the enhanced immune-stimulation associated with fatty-acid synthesis blockade. Our findings elucidate the role of fatty-acid synthesis in DC development and function and have implications to the design of DC vaccines for immunotherapy. PMID:23536633

Rehman, Adeel; Hemmert, Keith C.; Ochi, Atsuo; Jamal, Mohsin; Henning, Justin R.; Barilla, Rocky; Quesada, Juan P.; Zambirinis, Constantinos P.; Tang, Kerry; Ego-Osuala, Melvin; Rao, Raghavendra S.; Greco, Stephanie; Deutsch, Michael; Narayan, Suchithra; Pachter, H. Leon; Graffeo, Christopher S.; Acehan, Devrim; Miller, George

2013-01-01

234

Synthesis of cyclocaric acid A and comparison to material from Cyclocarya paliurus.  

Science.gov (United States)

Components previously reported from Cyclocarya paliurus include the oleananes cyclocaric acids A and B, with cyclocaric acid A possessing an oxetane ring. Isolation of cyclocaric acid A from the plant extract and comparison to the literature report show that the compound originally reported as cyclocaric acid A is, in fact, hederagenin. This was confirmed by independent synthesis of the oxetane and indicates that cyclocaric acid A may not actually be a natural product. PMID:25340252

Wright, Matthew E; Byrd, Jonathan; He, Chunnian; Dunlap, Norma

2014-11-26

235

Carbamate-directed hydroboration: Enantioselective synthesis of the excitatory amino acid 1-aminocyclopentane-1,3-dicarboxylic acid  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Carbamate-directed hydroboration (using BH3) of 1-substituted 3- cyclopentenes 2, 6 and 9 and an enantioselective synthesis of the excitatory amine acid 1-aminocyclopentane-1,3-dicarboxylic acid via carbamate-directed asymmetric hydroboration [90% de, 45% ee using (+)-IpcBH2] of cyclopentene 2 are described.

Hodgson, Dm; Thompson, AJ; Wadman, S.

1998-01-01

236

Synthesis and properties of carbohydrate-phosphate backbone-modified oligonucleotide analogues and nucleic acid mimetics  

Energy Technology Data Exchange (ETDEWEB)

Advances in the synthesis of oligo(deoxy)ribonucleotide analogues and nucleic acid mimetics made in the last decade are summarized. Attention is focused on new methods for the synthesis of derivatives with a modified ribose-phosphate backbone (phosphorothioate, boranophosphate, and nucleoside phosphonate derivatives) and derivatives devoid of the phosphate group. Among nucleic acid mimetics, conformationally restricted modified peptide nucleic acids, including those bearing a negative or positive charge, and morpholino oligomers are considered. Advantages and drawbacks of the main types of analogues as regards the complexity of the synthesis and the possibility of their application as antisense agents or reagents for hybridization analysis are compared.

Abramova, Tatyana V; Silnikov, Vladimir N [Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences (Russian Federation)

2011-05-31

237

Regulation of 5-Aminolevulinic Acid (ALA) Synthesis in Developing Chloroplasts 1  

Science.gov (United States)

Gabaculine and 4-amino-5-hexynoic acid (AHA) up to 3.0 millimolar concentration strongly inhibited 5-aminolevulinic acid (ALA) synthesis in developing cucumber (Cucumis sativus L. var Beit Alpha) chloroplasts, while they hardly affected protochlorophyllide (Pchlide) synthesis. Exogenous protoheme up to 1.0 micromolar had a similar effect. Exogenous glutathione also exhibited a strong inhibitory effect on ALA synthesis in organello but hardly inhibited Pchlide synthesis. Pchlide synthesis in organello was highly sensitive to inhibition by levulinic acid, both in the presence and in the absence of gabaculine, indicating that the Pchlide was indeed formed from precursor(s) before the ALA dehydratase step. The synthesis of Pchlide in the presence of saturating concentrations of glutamate was stimulated by exogenous ALA, confirming that Pchlide synthesis was limited at the formation of ALA. The gabaculine inhibition of ALA accumulation occurred whether levulinic acid or 4,6-dioxohepatonic acid was used in the ALA assay system. ALA overproduction was also observed in the absence of added glutamate and was noticeable after 10-minute incubation. These observations suggest that although Pchlide synthesis in organello is limited by ALA formation, it does not utilize all the ALA that is made in the in organello assay system. Gabaculine, AHA, and probably also protoheme, inhibit preferentially the formation of that portion of ALA that is not destined for Pchlide. A model proposing a heterogenous ALA pool is described. PMID:16667243

Huang, Laiqiang; Castelfranco, Paul A.

1990-01-01

238

Fatty Acid Biosynthesis IX. : Fatty Acid Synthesis from Enzymically and Chemically Acetylated Rabbit Mammary Gland Fatty Acid Synthetase.  

DEFF Research Database (Denmark)

# 1. I. [I-14C]Acetate was covalently bound to rabbit mammary gland fatty acid synthetase by enzymic transacylation from [I-14C]acetyl-CoA. Per mole of enzyme 2 moles of acetate were bound to thiol groups and up to I mole of acetate was bound to non-thiol groups. # 2. 2. The acetyl-fatty acid synthetase complex was isolated free from acetyl-CoA. It was rapidly hydrolysed at 30°C, but hydrolysis was greatly diminished at o°C and triacetic lactone synthesis occurred. In the presence of malonyl-CoA and NADPH, all the acetate bound to fatty acid synthetase was incorporated into long-chain fatty acids. Hydrolysis of bound acetate and incorporation of bound acetate into fatty acids were inhibited to the same extent by guanidine hydrochloride. # 3. 3. Acetate was also covalently bound to fatty acid synthetase by chemical acetylation with [I-14C]acetic anhydride in the absence of CoASH. A total of 60 moles of acetate were bound per mole of fatty acid synthetase, with 20–25 moles being bound to thiol groups per mole of enzyme. Acylation did not inhibit enzyme activity. The majority of the bound acetate was stable to hydrolysis at o °C. Out of the 60 moles of acetate bound per mole of acetylated enzyme, up to 20 moles were incorporated into fatty acids in the presence of malonyl-CoA and NADPH. # 4. 4. Due to the rapid hydrolysis of acetyl-fatty acid synthetase prepared from both acetyl-CoA and acetic anhydride, direct carboxylation of acetyl-fatty acid synthetase to form malonyl-fatty acid synthetase could not be demonstrated by CO2 fixation under the experimental conditions used. With acetic anhydride as acetyl donor, there was a low rate of incorporation of acetate into fatty acids in the presence of NADPH but absence of added malonyl-CoA. This could be due to direct carboxylation of the acetate bound to fatty acid synthetase or, if any CoA were associated with the fatty acid synthetase, to carboxylation of acetyl-CoA formed by chemical acetylation of this CoA.

Carey, E. M.; Hansen, Heinz Johs. Max

1972-01-01

239

Synthesis of new polyphosphonic acids, uranium extracting agents in a phosphoric medium  

International Nuclear Information System (INIS)

Synthesis of organic phosphorus compounds for liquid-liquid extraction of traces of uranium in concentrated phosphoric acid is studied in view of industrial applications. Diphosphonic acids and monoesters and also triphosphonic acids and related compounds are synthetized. Extraction tests show a better efficiency than OPPA

240

Synthesis of hyaluronic acid oligosaccharides and exploration of a fluorous-assisted approach  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The synthesis of hyaluronic acid oligomers (tri- and tetrasaccharide) is described. We have followed a pre-glycosylation oxidation strategy. Glucuronic acid units were directly employed in coupling reactions with suitably protected glucosamine derivatives. In order to simplify the puri?cation of synthetic intermediates, a ?uorous-assisted strategy has been also explored. Using this approach, a hyaluronic acid trisaccharide was prepared.

Macchione, Giuseppe; Paz, Jose? L.; Nieto, Pedro M.

2014-01-01

 
 
 
 
241

Thioacetic acid/NaSH-mediated synthesis of N-protected amino thioacids and their utility in peptide synthesis.  

Science.gov (United States)

Thioacids are recently gaining momentum due to their versatile reactivity. The reactivity of thioacids has been widely explored in the selective amide/peptide bond formation. Thioacids are generally synthesized from the reaction between activated carboxylic acids such as acid chlorides, active esters, etc., and Na2S, H2S, or NaSH. We sought to investigate whether the versatile reactivity of the thioacids can be tuned for the conversion of carboxylic acids into corresponding thioacids in the presence of NaSH. Herein, we report that thioacetic acid- and NaSH-mediated synthesis of N-protected amino thioacids from the corresponding N-protected amino acids, oxidative dimerization of thioacids, crystal conformations of thioacid oxidative dimers, and the utility of thioacids and oxidative dimers in peptide synthesis. Our results suggest that peptides can be synthesized without using standard coupling agents. PMID:24548175

Mali, Sachitanand M; Gopi, Hosahudya N

2014-03-21

242

Fatty Acids Induce Leukotriene C4 Synthesis in Macrophages in a Fatty Acid Binding Protein-Dependent Manner  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Obesity results in increased macrophage recruitment to adipose tissue that promotes a chronic low-grade inflammatory state linked to increased fatty acid efflux from adipocytes. Activated macrophages produce a variety of pro-inflammatory lipids such as leukotriene C4 (LTC4) and 5-, 12-, and 15-hydroxyeicosatetraenoic acid (HETE) suggesting the hypothesis that fatty acids may stimulate eicosanoid synthesis. To assess if eicosanoid production increases with obesity, adipose tissue of leptin def...

Long, Eric K.; Hellberg, Kristina; Foncea, Rocio; Hertzel, Ann V.; Suttles, Jill; Bernlohr, David A.

2013-01-01

243

Bile acid metabolism in cirrhosis. VIII. Quantitative evaluation of bile acid synthesis from [7 beta-3H]7 alpha-hydroxycholesterol and [G-3H]26-hydroxycholesterol  

International Nuclear Information System (INIS)

In order to evaluate more definitively the observed aberrations in the synthesis of cholic and chenodeoxycholic acids in patients with advanced cirrhosis, two bile acid biosynthesis pathways were examined by determining the efficiency of conversion of [3H]7 alpha-hydroxycholesterol and [3H] 26-hydroxycholesterol to primary bile acids. Bile acid kinetics were determined by administration of [14C]cholic and [14C]chenodeoxycholic acids. Cholic acid synthesis in cirrhotic patients was markedly depressed (170 vs 927 ?moles per day)( while chenodeoxycholic acid synthesis was reduced to a much lesser degree (227 vs 550 ?moles per day). The administration of [3H]7 alpha-hydroxycholesterol allowed for an evaluation of the major pathway of bile acid synthesis via the 7 alpha-hydroxylation of cholesterol. This compound was efficiently incorporated into primary bile acids by the two normal subjects (88 and 100%) and two cirrhotic patients (77 and 91%). However, the recovery of the label in cholic acid was slightly less in cirrhotic patients than in normal subjects. [3H]26-hydroxycholesterol was administered to ascertain the contribution of the 26-hydroxylation pathway to bile acid synthesis. All study subjects showed poor conversion (9 to 22%) of this intermediate into bile acids. The results of this study suggest that a major block in the bile acid synthesis pathway in cirrhosis is at the level of 7 alpha-hydroxrhosis is at the level of 7 alpha-hydroxylation of cholesterol (impairment of 7 alpha-hydroxylase) and/or in the feedback triggering mechanism regulating bile acid synthesis. The data also suggest that the 26-hydroxylation pathway in normal subjects and patients with cirrhosis is a minor contributor to synthesis of the primary bile acids. Therefore, the relative sparing of chenodeoxycholic acid synthesis observed in cirrhotic patients is not due to preferential synthesis of this bile acid via the 26-hydroxylation pathway

244

78 FR 9363 - Polyethylene Terephthalate Film, Sheet, and Strip From the People's Republic of China: Notice of...  

Science.gov (United States)

...Administration [A-570-924] Polyethylene Terephthalate Film, Sheet, and Strip...2\\ See Polyethylene Terephthalate Film, Sheet, and Strip...reconsider the SV for polyethylene terephthalate (``PET'')...

2013-02-08

245

Templated synthesis of nylon nucleic acids and characterization by nuclease digestion  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Nylon nucleic acids containing oligouridine nucleotides with pendent polyamide linkers and flanked by unmodified heteronucleotide sequences were prepared by DNA templated synthesis. Templation was more efficient than the single-stranded synthesis: Coupling step yields were as high as 99.2%, with up to 7 amide linkages formed in the synthesis of a molecule containing 8 modified nucleotides. Controlled digestion by calf spleen phosphodiesterase enabled the mapping of modified nucleotides in the...

Liu, Yu; Wang, Risheng; Ding, Liang; Sha, Roujie; Seeman, Nadrian C.; Canary, James W.

2012-01-01

246

Silicotungstic Acid Modified Bentonite: An Efficient Catalyst for Synthesis of Acetal Derivatives of Aldehydes and Ketones  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Acetals and ketals are among the important materials of organic synthesis and as protecting agent of carbonyl functionality. A milder, efficient and green synthesis of acetals and ketals has been developed using Silicotungstic acid modified Bentonite (STA-Ben) as a catalyst. STA-Ben has been synthesized and characterized by various analytical techniques. It has been found to be an efficient and reusable catalyst for the synthesis ...

Reshu Chaudhary; Monika Datta

2013-01-01

247

Bifunctional Role of Thiosalicylic Acid in the Synthesis of Silver Nanoparticles  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Conventional synthesis of silver nanoparticles employs a reducing agent and a capping agent. Surfactants are effec-tive capping agents as they prevent the aggregation of nanoparticles during storage and use. However, the biocompatibility of several of the surfactants is questionable. In this report, the use of thiosalicylic acid as both reducing and capping agent is reported. Compared to conventional synthesis, this methodology requires higher temperature for synthesis, which then is expected...

Ramasamy Indumathy; Kalarical Janardhanan Sreeram; Muralidharan Sriranjani; Cheravathoor Poulose Aby; Balachandran Unni Nair

2010-01-01

248

Alterations in growth and fatty acid profiles under stress conditions of Hansenula polymorpha defective in polyunsaturated fatty acid synthesis.  

Science.gov (United States)

Using chemical mutagenesis, mutants of Hansenula polymorpha that were defective in fatty acid synthesis were selected based on their growth requirements on saturated fatty acid mixtures. One mutant (S7) was incapable of synthesizing polyunsaturated fatty acids (PUFA), linoleic and ?-linolenic acids. A genetic analysis demonstrated that the S7 strain had a double lesion affecting fatty acid synthesis and ?(12)-desaturation. A segregant with a defect in PUFA synthesis (H69-2C) displayed normal growth characteristics in the temperature range of 20-42 °C through a modulation of the cellular fatty acid composition. Compared with the parental strain, this yeast mutant had increased sensitivity at low and high temperatures (15 and 48 °C, respectively) with an increased tolerance to oxidative stress. The responses to ethanol stress were similar for the parental and PUFA-defective strains. Myristic acid was also determined to play an essential role in the cell growth of H. polymorpha. These findings suggest that both the type of cellular fatty acids and the composition of fatty acids might be involved in the stress responsive mechanisms in this industrially important yeast. PMID:23645092

Sooksai, Sarintip; Chewchanlertfa, Pattsarun; Kaneko, Yoshinobu; Harashima, Satoshi; Laoteng, Kobkul

2013-08-01

249

The synthesis and investigation of some bile acids derivatives on the base of 3?, 7?, 12?-three hydro oxi cholane acids  

International Nuclear Information System (INIS)

In this chapter of book authors investigated the synthesis of some bile acids derivatives on the base of 3?, 7?, 12?-three hydro oxi cholane acids. As a result of this investigation worked up preparative methods of synthesis of glycerin ethers of chenodeoxycholic acid

250

Synthesis of 1-O-methylchlorogenic acid: reassignment of structure for MCGA3 isolated from bamboo (Phyllostachys edulis) leaves  

Science.gov (United States)

The first synthesis of 1-O-methylchlorogenic acid is described. The short and efficient synthesis of this compound provides laboratory-scale quantities of the material to investigate its biological properties. The synthesis involved C-1 alkylation of the known (-)-4,5-cyclohexylidenequinic acid lact...

251

An Easy microwave-assisted synthesis of sulfonamides directly from sulfonic acids  

Digital Repository Infrastructure Vision for European Research (DRIVER)

An easy and handy synthesis of sulfonamides directly from sulfonic acids or its sodium salts is reported. The reaction is performed under microwave irradiation, has shown a good functional group tolerance, and is high yielding.

Luca, Lidia Vera Giovanna; Giacomelli, Giampaolo

2008-01-01

252

The Synthesis of an Amino Acid Derivative and Spectroscopic Monitoring of Dipeptide Formation.  

Science.gov (United States)

Described are experiments to give students experience in the synthesis of peptides from amino acids and to use visible spectroscopy to measure a rate of reaction. The activities were designed for undergraduate courses. (RH)

Simmonds, Richard J.

1987-01-01

253

A Facile and Efficient Synthesis of N-aryl Imides Using Trifluoroacetic Acid  

Directory of Open Access Journals (Sweden)

Full Text Available An efficient protocol has been demonstrated for the synthesis of pthalimides, maleimides and succinimides in excellent yield using trifluoroacetic acid as the reaction medium and promoter.

Sunita B. Shinde

2011-04-01

254

Synthesis of Phosphatidylcholine Analogues Derived from Glyceric Acid: a New Class of Biologically Active Phospholipid Compounds  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Synthesis of a new class of phosphatidylcholine analogues derived from glyceric acid is reported for spectroscopic studies of phospholipases and conformation of phospholipid side-chains in biological membranes, using fluorescence resonance energy transfer (FRET) techniques.

Rosseto, Renato; Tcacenco, Celize M.; Ranganathan, Radha; Hajdu, Joseph

2008-01-01

255

Highly Efficient Procedure for the Synthesis of Fructone Fragrance Using a Novel Carbon based Acid  

Directory of Open Access Journals (Sweden)

Full Text Available The novel carbon based acid has been synthesized via one-step hydrothermal carbonization of furaldehyde and hydroxyethylsulfonic acid. A highly efficient procedure for the synthesis of fructone has been developed using the novel carbon based acid. The results showed that the catalyst possessed high activity for the reaction, giving a yield of over 95%. The advantages of high activity, stability, reusability and low cost for a simple synthesis procedure and wide applicability to various diols and ?-keto esters make this novel carbon based acid one of the best choices for the reaction.

Xuezheng Liang

2010-08-01

256

Poly(ethylene terephthalate-co-isophthalate) copolyesters obtained from ethylene terephthalate and isophthalate oligomers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A series of poly(ethylene terephthalate-co-isophthalate) copolyesters containing up to 50%-mole of isophthalic units were prepared by polycondensation from ethylene terephthalate and ethylene isophthalate fractions of linear oligomers containing from 5 to 6 repeating units in average. The polyesters were obtained in good yields and with high molecular weights. The microstructure of the copolyesters was studied as a function of reaction time by 13C-NMR showing that a random dist...

Ubach, Joan; Marti?nez Ilarduya Sa?ez Asteasu, Domingo Antxon; Quintana Vicente, Robert; Alla Bedahnane, Abdelilah; Mun?oz Guerra, Sebastia?n; Rude?, Elisabet

2010-01-01

257

Plasma-chemical modification of the structure and properties of poly(ethylene terephthalate) track membranes  

International Nuclear Information System (INIS)

A process of extraction of the low-molecular products of the synthesis from the poly(ethylene terephthalate) track membranes modified by plasma has been investigated. It is shown that the deposition of a thin polymeric hydrocarbon film by cyclohexane plasma on the membrane surface with preliminary treatment in a plasma of non-polymerizing gases, for example oxygen, allows one to produce membranes possessing a high productivity. Their advantages are much better hydrodynamic properties and a small amount of the low-molecular products of the synthesis extracted by organic solvents

258

Synthesis of L-glutamic acid stereospecifically labeled at C-4 with deuterium  

International Nuclear Information System (INIS)

4-[2H2]-L-glutamic acid was prepared in excellent yield by enzymatic reductive amination of 4-[2H2]-2-ketoglutaric acid. The synthesis of stereospecifically deuterated (4 R) and (4 S)-[4-2H2]-L-glutamic acids from (2 RS, 4 S) and (2 RS, 4 R)-4-hydroxyglutamic acids, involving a reduction step by sodium cyanoboro-deuteride, was shown to proceed with 75% inversion of configuration. (author)

259

High yield synthesis of some phosphonic acid derivatives as surface tethers for energy harvesting technologies  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Efficient synthesis of novel 6-(2-bromo-2-methyl propanoyloxy)hexyl phosphonic acid, dodecane di-phosphonic acid, 6-(thiophene-3-carbonyloxy)hexyl phosphonic acid, octadecyl phosphonic acid and such other derivatives are reported here. These derivatives have a potential application as tethers to nanoparticle surfaces that can promote efficient electron transfer process in solar energy conversion. DOI: http://dx.doi.org/10.4314/bcse.v28i1.17

Mungalimane, A.

2014-01-01

260

High yield synthesis of some phosphonic acid derivatives as surface tethers for energy harvesting technologies  

Directory of Open Access Journals (Sweden)

Full Text Available Efficient synthesis of novel 6-(2-bromo-2-methyl propanoyloxyhexyl phosphonic acid, dodecane di-phosphonic acid, 6-(thiophene-3-carbonyloxyhexyl phosphonic acid, octadecyl phosphonic acid and such other derivatives are reported here. These derivatives have a potential application as tethers to nanoparticle surfaces that can promote efficient electron transfer process in solar energy conversion. DOI: http://dx.doi.org/10.4314/bcse.v28i1.17

A. Mungalimane

2014-01-01

 
 
 
 
261

Activities of Heterogeneous Acid-Base Catalysts for Fragrances Synthesis: A Review  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper reviews various types of heterogeneous acid-base catalysts for fragrances preparation. Catalytic activities of various types of heterogeneous acid and base catalysts in fragrances preparation, i.e. non-zeolitic, zeolitic, and mesoporous molecular sieves have been reported. Generally, heterogeneous acid catalysts are commonly used in fragrance synthesis as compared to heterogeneous base catalysts. Heteropoly acids and hydrotalcites type catalysts are widely used as heterogeneous aci...

Hartati Hartati; Mardi Santoso; Sugeng Triwahyono; Didik Prasetyoko

2013-01-01

262

Synthesis and characterization of mesoporous titanium modified with tungstosilicic acid  

International Nuclear Information System (INIS)

The synthesis of titania uses urea to form pores, with sol-gel type reactions catalyzed by HCI. During the gelation process an alcoholic solution of tungstosilicic acid (TSA) is added. The amount of acid varied in order to obtain TSA contents of 0%, 10%, 20% and 30 % in weight in the material (TiTSA00, TiTSA10, TiTSA20 and TiTSA30, respectively). The urea was extracted with water and the solid thus obtained was treated at 100, 200, 300, 400, 500 y 600oC. The solids obtained were determined to be mesoporous with a pore diameter (Dp) greater than 3.0 nm. The specific area (SBET) decreases and the Dp increases when the TSA content is increased. When the calcination temperature increases SBET decreases and this reduction is less when the TSA content in the solids increases. The XRD diagrams of the samples modified with TSA only display the characteristic peaks of the anatase phase. The crystal size (DC) of the solids treated at 100oC, does not depend on the content of TSA and they are about 5.0 nm. While the crystallinity and DC increase with the increase in the temperature of calcination. According to the FT-IR spectrum the [SiW12O40]4- type is mostly present in the solids. The DRS spectrums of the samples TiTSA00T100, TiTSA10T100, TiTSA20T100 and TiTSA30T100 show continuous shift to the network of the threshtinuous shift to the network of the threshold at the beginning of the absorption band as a result of the addition of TSA. The band gap values obtained from the DRS UV-VIS spectrums are slightly less than those reported for the anatase (au)

263

Synthesis of carboranyl amino acids, hydantoins, and barbiturates  

Energy Technology Data Exchange (ETDEWEB)

The syntheses of three novel boronated hydantoins, 5-(o-carboran-1-ylmethyl)hydantoin, 14, the tetraphenylphosphonium salt of 7-(hydantoin-5-ylmethyl)dodecahydro-7,8-dicarba-nido-undecaborate, 15, 5-(o-carboran-1-ylmethyl)-2-thiohydantoin, 16, and two new barbiturates, 5,5-bis(but-2-ynyl)barbiturate, 18, and 5,5-bis[(2-methyl-0-carboran-1-yl)methyl]barbiturate, 20, are described. Hydantoins 14-16 were synthesized from o-carboranylalanine (Car, 13). The detailed synthesis of Car and two other carborane-containing amino acids, O-(o-carboran-1-ylmethyl)tyrosine (CBT, 5a) and p-(o-carboran-1-yl)phenylalanine (CBPA, 5b), presented earlier as a communication, {sup 16} are also described. Hydantoin 14 and barbiturates 18 and 20 were tested for their potential anticonvulsant activity. Initial qualitative screening showed moderate activities for hydantoin 14 and barbiturate 18. Barbiturate 20 had no activity. Compound 14 appeared to be nontoxic at doses of 300 mg/kg (mice, ip) and 50 mg/kg (rats, oral). However, 18 was very toxic under similar conditions.

Wyzlic, I.M.; Tjarks, W.; Soloway, A.H. [Ohio State Univ., Columbus, OH (United States)] [and others

1996-07-31

264

Synthesis of carboranyl amino acids, hydantoins, and barbiturates  

International Nuclear Information System (INIS)

The syntheses of three novel boronated hydantoins, 5-(o-carboran-1-ylmethyl)hydantoin, 14, the tetraphenylphosphonium salt of 7-(hydantoin-5-ylmethyl)dodecahydro-7,8-dicarba-nido-undecaborate, 15, 5-(o-carboran-1-ylmethyl)-2-thiohydantoin, 16, and two new barbiturates, 5,5-bis(but-2-ynyl)barbiturate, 18, and 5,5-bis[(2-methyl-0-carboran-1-yl)methyl]barbiturate, 20, are described. Hydantoins 14-16 were synthesized from o-carboranylalanine (Car, 13). The detailed synthesis of Car and two other carborane-containing amino acids, O-(o-carboran-1-ylmethyl)tyrosine (CBT, 5a) and p-(o-carboran-1-yl)phenylalanine (CBPA, 5b), presented earlier as a communication, 16 are also described. Hydantoin 14 and barbiturates 18 and 20 were tested for their potential anticonvulsant activity. Initial qualitative screening showed moderate activities for hydantoin 14 and barbiturate 18. Barbiturate 20 had no activity. Compound 14 appeared to be nontoxic at doses of 300 mg/kg (mice, ip) and 50 mg/kg (rats, oral). However, 18 was very toxic under similar conditions

265

Distribution, synthesis, and absorption of kynurenic acid in plants.  

Science.gov (United States)

Kynurenic acid (KYNA) is an endogenous antagonist of the ionotropic glutamate receptors and the ?7 nicotinic acetylcholine receptor as well as an agonist of the G-protein-coupled receptor GPR35. In this study, KYNA distribution and synthesis in plants as well as its absorption was researched. KYNA level was determined by means of the high-performance liquid chromatography with fluorescence detection. KYNA was found in leaves, flowers, and roots of tested medicinal herbs: dandelion (Taraxacum officinale), common nettle (Urtica dioica), and greater celandine (Chelidoniummajus). The highest concentration of this compound was detected in leaves of dandelion--a mean value of 0.49 µg/g wet weight. It was shown that KYNA can be synthesized enzymatically in plants from its precursor, L-kynurenine, or absorbed by plants from the soil. Finally, the content of KYNA was investigated in 21 herbal tablets, herbal tea, herbs in sachets, and single herbs in bags. The highest content of KYNA in a maximum daily dose of herbal medicines appeared in St. John's wort--33.75 µg (tablets) or 32.60 µg (sachets). The pharmacological properties of KYNA and its presence in high concentrations in medicinal herbs may suggest that it possesses therapeutic potential, especially in the digestive system and should be considered a new valuable dietary supplement. PMID:21157681

Turski, Michal P; Turska, Monika; Zgrajka, Wojciech; Bartnik, Magdalena; Kocki, Tomasz; Turski, Waldemar A

2011-05-01

266

Synthesis and Characterization of Fatty Acid/Amino Acid Self-Assemblies  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, we discuss the synthesis and self-assembling behavior of new copolymers derived from fatty acid/amino acid components, namely dimers of linoleic acid (DLA and tyrosine derived diphenols containing alkyl ester pendent chains, designated as “R” (DTR. Specific pendent chains were ethyl (E and hexyl (H. These poly(aliphatic/aromatic-ester-amides were further reacted with poly(ethylene glycol (PEG and poly(ethylene glycol methyl ether of different molecular masses, thus resulting in ABA type (hydrophilic-hydrophobic-hydrophilic triblock copolymers. We used Fourier transform infrared (FTIR and nuclear magnetic resonance (NMR spectroscopies to evaluate the chemical structure of the final materials. The molecular masses were estimated by gel permeation chromatography (GPC measurements. The self-organization of these new polymeric systems into micellar/nanospheric structures in aqueous environment was evaluated using ultraviolet/visible (UV-VIS spectroscopy, dynamic light scattering (DLS and transmission electron microscopy (TEM. The polymers were found to spontaneously self-assemble into nanoparticles with sizes in the range 196–239 nm and critical micelle concentration (CMC of 0.125–0.250 mg/mL. The results are quite promising and these materials are capable of self-organizing into well-defined micelles/nanospheres encapsulating bioactive molecules, e.g., vitamins or antibacterial peptides for antibacterial coatings on medical devices.

Joanna Gajowy

2014-10-01

267

Synthesis and Characterization of Fatty Acid/Amino Acid Self-Assemblies  

Science.gov (United States)

In this paper, we discuss the synthesis and self-assembling behavior of new copolymers derived from fatty acid/amino acid components, namely dimers of linoleic acid (DLA) and tyrosine derived diphenols containing alkyl ester pendent chains, designated as “R” (DTR). Specific pendent chains were ethyl (E) and hexyl (H). These poly(aliphatic/aromatic-ester-amide)s were further reacted with poly(ethylene glycol) (PEG) and poly(ethylene glycol methyl ether) of different molecular masses, thus resulting in ABA type (hydrophilic-hydrophobic-hydrophilic) triblock copolymers. We used Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopies to evaluate the chemical structure of the final materials. The molecular masses were estimated by gel permeation chromatography (GPC) measurements. The self-organization of these new polymeric systems into micellar/nanospheric structures in aqueous environment was evaluated using ultraviolet/visible (UV-VIS) spectroscopy, dynamic light scattering (DLS) and transmission electron microscopy (TEM). The polymers were found to spontaneously self-assemble into nanoparticles with sizes in the range 196–239 nm and critical micelle concentration (CMC) of 0.125–0.250 mg/mL. The results are quite promising and these materials are capable of self-organizing into well-defined micelles/nanospheres encapsulating bioactive molecules, e.g., vitamins or antibacterial peptides for antibacterial coatings on medical devices. PMID:25347356

Gajowy, Joanna; Bolikal, Durgadas; Kohn, Joachim; El Fray, Miroslawa

2014-01-01

268

Aqueous Microwave-Assisted Solid-Phase Synthesis Using Boc-Amino Acid Nanoparticles  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We have previously developed water-based microwave (MW)-assisted peptide synthesis using Fmoc-amino acid nanopaticles. It is an organic solvent-free, environmentally friendly method for peptide synthesis. Here we describe water-based MW-assisted solid-phase synthesis using Boc-amino acid nanoparticles. The microwave irradiation allowed rapid solid-phase reaction of nanoparticle reactants on the resin in water. We also demonstrated the syntheses of Leu-enkephalin, Tyr-Gly-Gly-Phe-Leu-OH, and d...

Yoshinobu Fukumori; Hideki Ichikawa; Yoshimi Nozawa; Natsuki Shinozaki; Keiko Hojo

2013-01-01

269

[Effect of 2-ketogluconic acid synthesis on the exopolysaccharide production in a Rhizobium meliloti strain].  

Science.gov (United States)

Two categories of carbon substrates are defined for Rhizobium meliloti: the first favours the synthesis of exopolysaccharides (fructose belongs to this category) while the other is not suitable (glucose belongs to this category). With fructose, resting cells synthesize polysaccharides during more than 100 h and this synthesis is at its best in aerobic conditions at 30 degrees C. With glucose, 2-ketogluconic acid accumulates and rapidly stops the synthesis. The method used to stop this acidification allows with glucose a synthesis which can be compared to the one obtained with fructose. PMID:43767

Courtois, B; Hornez, J P; Derieux, J C

1979-10-01

270

Suppression of glycosaminoglycan synthesis by articular cartilage, but not of hyaluronic acid synthesis by synovium, after exposure to radiation  

International Nuclear Information System (INIS)

We recently found that injection of 2 mCi of yttrium 90 (90Y; approximately 23,000 rads) into normal canine knees stimulated glycosaminoglycan (GAG) synthesis by femoral condylar cartilage. The present investigation was conducted to determine whether radiation affects cartilage metabolism directly. Rates of GAG synthesis and degradation in normal canine articular cartilage were studied following irradiation. Cultured synovium from the same knees was treated similarly, to determine the effects of irradiation on hyaluronic acid synthesis. Twenty-four hours after exposure to 1,000 rads, 10,000 rads, or 50,000 rads, 35S-GAG synthesis by the cartilage was 93%, 69%, and 37%, respectively, of that in control, nonirradiated cartilage. The effect was not rapidly reversible: 120 hours after exposure to 50,000 rads, GAG synthesis remained at only 28% of the control level. Autoradiography showed marked suppression of 35S uptake by chondrocytes after irradiation. Cartilage GAG degradation was also increased following irradiation: 4 hours and 8 hours after exposure to 50,000 rads, the cartilage GAG concentration was only 66% and 54%, respectively, of that at time 0, while corresponding values for control, nonirradiated cartilage were 90% and 87%. In contrast to its effects on cartilage GAG metabolism, radiation at these levels had no effect on synovial hyaluronic acid synthesis

271

Linkages between deoxyribonucleic acid synthesis and cell division in Myxococcus xanthus.  

Science.gov (United States)

Addition of chloramphenicol or 0.5 M glycerol to growing Myxococcus xanthus resulted in an immediate cessation of cell division and 40% net increase in deoxyribonucleic acid (DNA). Although the chloramphenicol-treated cells divided in the presence of nalidixic acid after chloramphenicol was removed, glycerol-induced myxospores required DNA synthesis for subsequent cell division. Myxospores prepared from chloramphenicol-treated cells lost this potential to divide in the presence of nalidixic acid. The "critical period" of DNA synthesis necessary for cell division after germination overlapped in time (3 to 5 h) with initiation of net DNA synthesis. The length of the critical period of DNA synthesis was estimated at 12 min, or 5% of the M. xanthus chromosome. The requirement for cell division during germination also involved ribonucleic acid and protein synthesis after DNA synthesis. The data suggest that replication at or near the origin of the chromosome triggers the formation of a protein product that is necessary but not sufficient for subsequent cell division; DNA termination is also required. During myxospore formation, the postulated protein is destroyed, thereby reestablishing and making apparent this linkage between early DNA synthesis and cell division. PMID:824278

Kimchi, A; Rosenberg, E

1976-10-01

272

Two modifications of layered cobaltous terephthalate: Crystal structures and magnetic properties  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The synthesis, characterization, crystal structure, and magnetic properties of Co2(OH)2BDC and Co(H2O)2BDC (BDC is benzene 1,4-dicarboxylate or terephthalate, O2CC6H4CO2) are reported. Co2(OH)2BDC (C2/m, a=19.952, b=3.286, c=6.295 Å, ?=95.84°, Z=2, V=410.6 Å3) consists of two types of edge-sharing CoO6 chains that are connected to each other by OH (Co-O-Co bridges) to form layers that are further joined together through terephthalate. It exhibits unusual magnetic properties: above 48 K it...

Kurmoo, M.; Kumagai, H.; Green, Ma; Lovett, Bw; Blundell, Sj; Ardavan, A.; Singleton, J.

2001-01-01

273

Crystal structure of Spot 14, a modulator of fatty acid synthesis  

Energy Technology Data Exchange (ETDEWEB)

Spot 14 (S14) is a protein that is abundantly expressed in lipogenic tissues and is regulated in a manner similar to other enzymes involved in fatty acid synthesis. Deletion of S14 in mice decreased lipid synthesis in lactating mammary tissue, but the mechanism of S14's action is unknown. Here we present the crystal structure of S14 to 2.65 {angstrom} and biochemical data showing that S14 can form heterodimers with MIG12. MIG12 modulates fatty acid synthesis by inducing the polymerization and activity of acetyl-CoA carboxylase, the first committed enzymatic reaction in the fatty acid synthesis pathway. Coexpression of S14 and MIG12 leads to heterodimers and reduced acetyl-CoA carboxylase polymerization and activity. The structure of S14 suggests a mechanism whereby heterodimer formation with MIG12 attenuates the ability of MIG12 to activate ACC.

Colbert, Christopher L.; Kim, Chai-Wan; Moon, Young-Ah; Henry, Lisa; Palnitkar, Maya; McKean, William B.; Fitzgerald, Kevin; Deisenhofer, Johann; Horton, Jay D.; Kwon, Hyock Joo (Alnylam Pharm.); (UTSMC)

2011-09-06

274

The effect of nalidixic acid, rifampicin and chloramphenicol on the synthesis of phospholipase C in Bacillus cereus  

International Nuclear Information System (INIS)

The effect of nalidixic acid, rifampicin and chloramphenicol on the synthesis of phospholipase C (EC 3.1.4.3) has been studied in washed Bacillus cereus cells resuspended in nutrient broth. In the absence of inhibitors, the synthesis showed a biphasic pattern. No synthesis or release of enzyme was found in the presence of chloramphenicol. When rifampicin was added, phospholipase C synthesis for 10-15 min. Nalidixic acid, at concentrations which inhibited DNA synthesis completely, permitted the synthesis of phospholipase C at the same rate and for a similar length of time as rifampicin. (author)

275

A new synthesis of double labeled [7,9-13C2] folic acid  

International Nuclear Information System (INIS)

A convenient small scale chemical synthesis of double labeled folic acid with 13C at positions C-7 and C-9 is reported. [1,3-13C2] acetone was converted into folic acid in two steps, with [1, 1, 3]-trichloroacetone as the labeled intermediate. (Author)

276

A Three Step Synthesis of 11-Cycloheptylundecanoic Acid, a Component of the Thermoacidophile Alicyclobacillus cycloheptanicus  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A simple synthesis of the methyl ester of 11-cycloheptylundecanoic acid (1), isolated from the lipid fraction of the thermoacidofile, Alicyclobacillus cycloheptanicus has been developed. This involved regioselective Grignard coupling between cycloheptylmagnesium bromide and methyl 11-bromoundecanoate (2), prepared from 10- undecanoic acid.

Mamdapur, Vasant R.; Hassarajani, Sham A.

1998-01-01

277

A Three Step Synthesis of 11-Cycloheptylundecanoic Acid, a Component of the Thermoacidophile Alicyclobacillus cycloheptanicus  

Directory of Open Access Journals (Sweden)

Full Text Available A simple synthesis of the methyl ester of 11-cycloheptylundecanoic acid (1, isolated from the lipid fraction of the thermoacidofile, Alicyclobacillus cycloheptanicus has been developed. This involved regioselective Grignard coupling between cycloheptylmagnesium bromide and methyl 11-bromoundecanoate (2, prepared from 10- undecanoic acid.

Vasant R. Mamdapur

1998-02-01

278

INFLUENCE OF THE SYNTHESIS PARAMETERS ON SOME TEXTURAL PROPERTIES OF ROMANIAN ACID ACTIVATED BENTONITE  

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This paper presents the influence of synthesis parameters (concentration of acid solution and the solid: liquid ratio) on textural characteristics of bentonite activated clays: nitrogen adsorption/desorption isotherms, surface and pore size distribution. Acid activated clays present higher specific surface area than the natural bentonite used as feed stock and a better adsorption capacity.

URSU ALINA VIOLETA; JINESCU GHEORGHITA; NISTOR ILEANA DENISA; GEORGESCU ANA MARIA; MUNTIANU GHIMICIU GABRIELA; SILION MIHAELA

2010-01-01

279

INFLUENCE OF THE SYNTHESIS PARAMETERS ON SOME TEXTURAL PROPERTIES OF ROMANIAN ACID ACTIVATED BENTONITE  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents the influence of synthesis parameters (concentration of acid solution and the solid: liquid ratio on textural characteristics of bentonite activated clays: nitrogen adsorption/desorption isotherms, surface and pore size distribution. Acid activated clays present higher specific surface area than the natural bentonite used as feed stock and a better adsorption capacity.

URSU ALINA VIOLETA

2010-08-01

280

Pyrazinoic Acid Decreases the Proton Motive Force, Respiratory ATP Synthesis Activity, and Cellular ATP Levels?†  

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Pyrazinoic acid, the active form of the first-line antituberculosis drug pyrazinamide, decreased the proton motive force and respiratory ATP synthesis rates in subcellular mycobacterial membrane assays. Pyrazinoic acid also significantly lowered cellular ATP levels in Mycobacterium bovis BCG. These results indicate that the predominant mechanism of killing by this drug may operate by depletion of cellular ATP reserves.

Lu, P.; Haagsma, A. C.; Pham, H.; Maaskant, J. J.; Mol, S.; Lill, H.; Bald, D.

2011-01-01

 
 
 
 
281

Exogenous fatty acids affect CDP-choline pathway to increase phosphatidylcholine synthesis in granular pneumocytes  

International Nuclear Information System (INIS)

Regulation of phosphatidylcholine (PC) synthesis in rat granular pneumocytes isolated by tryptic digestion of lungs and maintained in primary culture for 24 h was investigated by following effects of exogenous fatty acids on [3H-methyl]choline incorporation into PC and disaturated PC (DSPC). At 0.1 mM choline, the rate of choline incorporation into PC and DSPC was 440 +/- and 380 +/- 50 pmol/h/ug Pi (mean +/- SE, n=3-5), respectively, and was linear for up to 3 h. PC synthesis was significantly increased by 0.1 mM each of palmitic, oleic, linoleic, or linolenic acid. However, synthesis of DSPC was increased only by palmitic acid and this increase was prevented by addition of oleic acid suggesting lack of effect on the remodeling pathway. Pulse-chase experiments with choline in absence or presence of palmitic or oleic acid showed that the label declined in choline phosphate and increased in PC more rapidly in presence of either of the fatty acids, suggesting rapid conversion of choline phosphate to PC. Microsomal choline phosphate cytidyltransferase activity in cells preincubated without or with palmitic acid for 3 h was 0.81 +/- 0.07 and 1.81 +/- 0.09 nmol choline phosphate converted/min/mg protein (n=4). These results suggest that in granular pneumocytes, exogenous fatty acids modulate PC synthesis by increasing choline phosphate cytidyltransferase activity

282

Potency of individual bile acids to regulate bile acid synthesis and transport genes in primary human hepatocyte cultures.  

Science.gov (United States)

Bile acids (BAs) are known to regulate their own homeostasis, but the potency of individual bile acids is not known. This study examined the effects of cholic acid (CA), chenodeoxycholic acid (CDCA), deoxycholic acid (DCA), lithocholic acid (LCA) and ursodeoxycholic acid (UDCA) on expression of BA synthesis and transport genes in human primary hepatocyte cultures. Hepatocytes were treated with the individual BAs at 10, 30, and 100?M for 48 h, and RNA was extracted for real-time PCR analysis. For the classic pathway of BA synthesis, BAs except for UDCA markedly suppressed CYP7A1 (70-95%), the rate-limiting enzyme of bile acid synthesis, but only moderately (35%) down-regulated CYP8B1 at a high concentration of 100?M. BAs had minimal effects on mRNA of two enzymes of the alternative pathway of BA synthesis, namely CYP27A1 and CYP7B1. BAs increased the two major target genes of the farnesoid X receptor (FXR), namely the small heterodimer partner (SHP) by fourfold, and markedly induced fibroblast growth factor 19 (FGF19) over 100-fold. The BA uptake transporter Na(+)-taurocholate co-transporting polypeptide was unaffected, whereas the efflux transporter bile salt export pump was increased 15-fold and OST?/? were increased 10-100-fold by BAs. The expression of the organic anion transporting polypeptide 1B3 (OATP1B3; sixfold), ATP-binding cassette (ABC) transporter G5 (ABCG5; sixfold), multidrug associated protein-2 (MRP2; twofold), and MRP3 (threefold) were also increased, albeit to lesser degrees. In general, CDCA was the most potent and effective BA in regulating these genes important for BA homeostasis, whereas DCA and CA were intermediate, LCA the least, and UDCA ineffective. PMID:25055961

Liu, Jie; Lu, Hong; Lu, Yuan-Fu; Lei, Xiaohong; Cui, Julia Yue; Ellis, Ewa; Strom, Stephen C; Klaassen, Curtis D

2014-10-01

283

Synthesis of deuterium-labelled methylphenidate, p-hydroxy-methylphenidate, ritalinic acid and p-hydroxyritalinic acid  

Energy Technology Data Exchange (ETDEWEB)

The synthesis of threo-dl-methylphenidate (Ritalin 1), threo-dl-p-hydroxy-methylphenidate (3), threo-dl-ritalinic acid (2), and threo-dl-p-hydroxyritalinic acid (4) with deuterium incorporated in the piperidine ring is described. These compounds were synthesized for use as internal standards for mass fragmentographic assays of methylphenidate and its metabolites. The synthetic scheme described resulted in less than 0.05% /sup 2/H/sub 0/ in the piperidine ring in any of the preparations.

Patrick, K.; Kilts, C.; Breese, G. (North Carolina Univ., Chapel Hill (USA). School of Medicine)

1982-04-01

284

Synthesis of deuterium-labelled methylphenidate, p-hydroxy-methylphenidate, ritalinic acid and p-hydroxyritalinic acid  

International Nuclear Information System (INIS)

The synthesis of threo-dl-methylphenidate (Ritalin 1), threo-dl-p-hydroxy-methylphenidate (3), threo-dl-ritalinic acid (2), and threo-dl-p-hydroxyritalinic acid (4) with deuterium incorporated in the piperidine ring is described. These compounds were synthesized for use as internal standards for mass fragmentographic assays of methylphenidate and its metabolites. The synthetic scheme described resulted in less than 0.05% 2H0 in the piperidine ring in any of the preparations. (author)

285

Selective inhibition of leukotriene C4 synthesis in human neutrophils by ethacrynic acid  

International Nuclear Information System (INIS)

Addition of glutathione S-transferase inhibitors, ethyacrynic acid (ET), caffeic acid (CA), and ferulic acid (FA) to human neutrophils led to inhibition of leukotriene C4 (LTC4) synthesis induced by calcium ionophore A23187. ET is the most specific of these inhibitors for it had little effect on LTB4, PGE2, and 5-HETE synthesis. The inhibition of LTC4 was irreversible and time dependent. ET also had little effect on 3H-AA release from A23187-stimulated neutrophils

286

Radiotracer studies on the synthesis of prorennin and rennin using 14C-amino acids  

International Nuclear Information System (INIS)

In vivo incorporation of 14C-amino acids into the prorennin and rennin fractions of the abomasal tissue of the intact animal (i.e. calf) has been investigated by : (1) intravenous injection of the label and subsequent isolation of rennin and prorennin fractions from the excised abomasum and (2) feeding. of milk whey fortified with the label to a fistulated kid and subsequent processing of the abomasal juice for rennet extraction. Prorennin incorporates more radioactivity than rennin. This indicates that abomasal tissue uses blood amino acids for prorennin synthesis, but amino acids fed through dietary channels may not be used for rennin synthesis. (M.G.B.)

287

75 FR 10758 - Polyethylene Terephthalate Film, Sheet and Strip from India: Initiation of Antidumping Duty and...  

Science.gov (United States)

...A-533-824, C-533-825] Polyethylene Terephthalate Film, Sheet and Strip...duty (CVD) orders on Polyethylene Terephthalate Film, Sheet and Strip...Antidumping Duty Order: Polyethylene Terephthalate Film, Sheet, and...

2010-03-09

288

77 FR 14501 - Polyethylene Terephthalate Film, Sheet and Strip From India: Extension of Time Limit for...  

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...Administration [A-533-824] Polyethylene Terephthalate Film, Sheet and Strip...duty (AD) order on polyethylene terephthalate film, sheet and strip...September 20, 2011. See Polyethylene Terephthalate Film, Sheet and...

2012-03-12

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76 FR 30910 - Polyethylene Terephthalate Film, Sheet, and Strip From India: Final Results of Countervailing...  

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...Administration [C-533-825] Polyethylene Terephthalate Film, Sheet, and Strip...new shipper review of polyethylene terephthalate film, sheet and strip...Since the issuance of Polyethylene Terephthalate Film, Sheet, and...

2011-05-27

290

75 FR 69629 - Polyethylene Terephthalate Film, Sheet, and Strip From the People's Republic of China: Extension...  

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...Administration [A-570-924] Polyethylene Terephthalate Film, Sheet, and Strip...administrative review on polyethylene terephthalate film, sheet, and strip...of this review. See Polyethylene Terephthalate Film, Sheet, and...

2010-11-15

291

76 FR 76943 - Polyethylene Terephthalate Film, Sheet, and Strip From India: Final Results of Antidumping Duty...  

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...Administration [A-533-824] Polyethylene Terephthalate Film, Sheet, and Strip...antidumping duty order on polyethylene terephthalate film (PET Film) from...1\\ See Polyethylene Terephthalate Film, Sheet, and...

2011-12-09

292

78 FR 9670 - Polyethylene Terephthalate Film, Sheet, and Strip From India: Final Results of Administrative...  

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...Administration [A-533-824] Polyethylene Terephthalate Film, Sheet, and Strip...antidumping duty order on polyethylene terephthalate film (PET Film) from...1\\ See Polyethylene Terephthalate Film, Sheet, and...

2013-02-11

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78 FR 35245 - Polyethylene Terephthalate Film, Sheet, and Strip From the People's Republic of China: Final...  

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...Administration [A-570-924] Polyethylene Terephthalate Film, Sheet, and Strip...antidumping duty order on polyethylene terephthalate film, sheet, and strip...1\\ See Polyethylene Terephthalate Film, Sheet, and...

2013-06-12

294

76 FR 30908 - Polyethylene Terephthalate Film, Sheet, and Strip From India: Final Results of Antidumping Duty...  

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...Administration [A-533-824] Polyethylene Terephthalate Film, Sheet, and Strip...new shipper review of polyethylene terephthalate film, sheet and strip...Since the issuance of Polyethylene Terephthalate Film, Sheet, and...

2011-05-27

295

78 FR 78333 - Polyethylene Terephthalate Film, Sheet, and Strip From the People's Republic of China...  

Science.gov (United States)

...Administration [A-570-924] Polyethylene Terephthalate Film, Sheet, and Strip...antidumping duty order on polyethylene terephthalate film, sheet, and strip...Administrative Review: Polyethylene Terephthalate Film, Sheet, and...

2013-12-26

296

75 FR 81570 - Polyethylene Terephthalate Film, Sheet, and Strip From India: Preliminary Results of Antidumping...  

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...Administration [A-533-824] Polyethylene Terephthalate Film, Sheet, and Strip...antidumping duty order on polyethylene terephthalate film, sheet, and strip...Antidumping Duty Order: Polyethylene Terephthalate Film, Sheet, and...

2010-12-28

297

77 FR 1668 - Polyethylene Terephthalate Film, Sheet and Strip From India: Rescission, in Part, of...  

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...Administration [C-533-825] Polyethylene Terephthalate Film, Sheet and Strip...duty (CVD) order on polyethylene terephthalate film, sheet and strip...September 20, 2011. See Polyethylene Terephthalate Film, Sheet and...

2012-01-11

298

76 FR 9753 - Polyethylene Terephthalate Film, Sheet, and Strip From the People's Republic of China: Final...  

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...Administration [A-570-924] Polyethylene Terephthalate Film, Sheet, and Strip...antidumping duty order on polyethylene terephthalate film, sheet, and strip...1\\ See Polyethylene Terephthalate Film, Sheet, and...

2011-02-22

299

78 FR 9668 - Polyethylene Terephthalate Film, Sheet, and Strip From Taiwan: Final Results of Antidumping Duty...  

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...Administration [A-533-824] Polyethylene Terephthalate Film, Sheet, and Strip...antidumping duty order on polyethylene terephthalate film (PET Film) from...1\\ See Polyethylene Terephthalate Film, Sheet, and...

2013-02-11

300

78 FR 2365 - Polyethylene Terephthalate Film, Sheet and Strip From India: Partial Rescission of Antidumping...  

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...Administration [A-533-824] Polyethylene Terephthalate Film, Sheet and Strip...duty (AD) order on polyethylene terephthalate film, sheet and strip...America), Inc. \\3\\ See Polyethylene Terephthalate (PET) Film,...

2013-01-11

 
 
 
 
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78 FR 50029 - Polyethylene Terephthalate Film, Sheet and Strip From Brazil: Preliminary Results of Antidumping...  

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...Administration [A-351-841] Polyethylene Terephthalate Film, Sheet and Strip...antidumping duty order on polyethylene terephthalate film, sheet and strip...Administrative Review of Polyethylene Terephthalate Film, Sheet and...

2013-08-16

302

75 FR 80457 - Polyethylene Terephthalate Film, Sheet and Strip From India: Extension of Time Limit for...  

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...Administration [A-533-824] Polyethylene Terephthalate Film, Sheet and Strip...antidumping duty order on polyethylene terephthalate film, sheet and strip...December 31, 2009. See Polyethylene Terephthalate Film, Sheet and...

2010-12-22

303

75 FR 69400 - Polyethylene Terephthalate Film, Sheet and Strip From India: Extension of Time Limit for...  

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...Administration [C-533-825] Polyethylene Terephthalate Film, Sheet and Strip...countervailing duty order on polyethylene terephthalate film, sheet and strip...December 31, 2009. See Polyethylene Terephthalate Film, Sheet and...

2010-11-12

304

76 FR 40325 - Polyethylene Terephthalate Film, Sheet, and Strip From the Republic of Korea: Preliminary Results...  

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...Administration [A-580-807] Polyethylene Terephthalate Film, Sheet, and Strip...antidumping duty order on polyethylene terephthalate film, sheet and strip...June 30, 2011. See Polyethylene Terephthalate Film, Sheet, and...

2011-07-08

305

77 FR 46687 - Polyethylene Terephthalate Film, Sheet, and Strip From India: Preliminary Results of Antidumping...  

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...Administration [A-533-824] Polyethylene Terephthalate Film, Sheet, and Strip...antidumping duty order on polyethylene terephthalate film, sheet, and strip...Antidumping Duty Order: Polyethylene Terephthalate Film, Sheet, and...

2012-08-06

306

75 FR 79336 - Polyethylene Terephthalate Film, Sheet and Strip From India: Extension of Time Limit for...  

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...Administration [C-533-825] Polyethylene Terephthalate Film, Sheet and Strip...countervailing duty order on polyethylene terephthalate film, sheet and strip...December 31, 2009. See Polyethylene Terephthalate Film, Sheet and...

2010-12-20

307

77 FR 9892 - Polyethylene Terephthalate Film, Sheet and Strip from India: Preliminary Intent to Rescind...  

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...Administration [C-533-825] Polyethylene Terephthalate Film, Sheet and Strip...duty (CVD) order on polyethylene terephthalate film, sheet and strip...Vacmet and Polypacks. See Polyethylene Terephthalate Film, Sheet and...

2012-02-21

308

78 FR 48147 - Polyethylene Terephthalate Film, Sheet, and Strip From India: Preliminary Results of...  

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...Administration [C-533-825] Polyethylene Terephthalate Film, Sheet, and Strip...duty (CVD) order on polyethylene terephthalate film, sheet and strip...pretreated, or primed polyethylene terephthalate film, sheet and...

2013-08-07

309

78 FR 79400 - Polyethylene Terephthalate Film, Sheet, and Strip From the People's Republic of China: Initiation...  

Science.gov (United States)

...Administration [A-570-924] Polyethylene Terephthalate Film, Sheet, and Strip...antidumping duty order on polyethylene terephthalate film, sheet, and strip...antidumping duty order on polyethylene terephthalate film, sheet, and...

2013-12-30

310

78 FR 48651 - Polyethylene Terephthalate Film, Sheet, and Strip From Taiwan; Preliminary Results of Antidumping...  

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...Administration [A-583-837] Polyethylene Terephthalate Film, Sheet, and Strip...antidumping duty order on polyethylene terephthalate film, sheet, and strip...1\\ See Polyethylene Terephthalate Film, Sheet and...

2013-08-09

311

78 FR 47276 - Polyethylene Terephthalate (PET) Film, Sheet, and Strip From India: Final Results of the...  

Science.gov (United States)

...Administration [C-533-825] Polyethylene Terephthalate (PET) Film, Sheet...countervailing duty order on polyethylene terephthalate (PET) film, sheet...Countervailing Duty Order: Polyethylene Terephthalate Film, Sheet, and...

2013-08-05

312

75 FR 75172 - Polyethylene Terephthalate Film, Sheet, and Strip From Brazil: Final Results of Antidumping Duty...  

Science.gov (United States)

...Administration [A-351-841] Polyethylene Terephthalate Film, Sheet, and Strip...antidumping duty order on polyethylene terephthalate film, sheet, and strip...parties to comment. See Polyethylene Terephthalate Film, Sheet, and...

2010-12-02

313

75 FR 49902 - Polyethylene Terephthalate Film, Sheet, and Strip From Taiwan: Preliminary Results of Antidumping...  

Science.gov (United States)

...Administration [A-583-837] Polyethylene Terephthalate Film, Sheet, and Strip...antidumping duty order on polyethylene terephthalate film, sheet, and strip...Antidumping Duty Order: Polyethylene Terephthalate Film, Sheet, and...

2010-08-16

314

76 FR 75870 - Polyethylene Terephthalate Film, Sheet, and Strip From Korea: Notice of Rescission of Antidumping...  

Science.gov (United States)

...Administration [A-580-807] Polyethylene Terephthalate Film, Sheet, and Strip...antidumping duty order on polyethylene terephthalate film, sheet, [[Page...antidumping duty order on polyethylene terephthalate film, sheet, and...

2011-12-05

315

76 FR 76941 - Polyethylene Terephthalate Film, Sheet, and Strip From Taiwan: Final Results of Antidumping Duty...  

Science.gov (United States)

...Administration [A-583-837] Polyethylene Terephthalate Film, Sheet, and Strip...antidumping duty order on polyethylene terephthalate film, sheet and strip...1\\ See Polyethylene Terephthalate Film, Sheet, and...

2011-12-09

316

78 FR 45512 - Polyethylene Terephthalate Film from India and Taiwan: Extension of Time Limits for Preliminary...  

Science.gov (United States)

...A-533-824, A-583-837] Polyethylene Terephthalate Film from India and Taiwan...duty (AD) orders on polyethylene terephthalate film (PET Film) from...Antidumping Duty Orders on Polyethylene Terephthalate Film from India and...

2013-07-29

317

76 FR 48122 - Polyethylene Terephthalate Film, Sheet, and Strip From Brazil: Preliminary Results of Antidumping...  

Science.gov (United States)

...Administration [A-351-841] Polyethylene Terephthalate Film, Sheet, and Strip...antidumping duty order on polyethylene terephthalate film, sheet, and strip...film from Brazil. See Polyethylene Terephthalate Film, Sheet, and...

2011-08-08

318

75 FR 52717 - Polyethylene Terephthalate Film, Sheet and Strip From India: Extension of Time Limit for...  

Science.gov (United States)

...Administration [A-533-824] Polyethylene Terephthalate Film, Sheet and Strip...antidumping duty order on polyethylene terephthalate film, sheet and strip...December 31, 2009. See Polyethylene Terephthalate Film, Sheet and...

2010-08-27

319

76 FR 71512 - Polyethylene Terephthalate Film, Sheet, and Strip From Korea: Final Results of Antidumping Duty...  

Science.gov (United States)

...Administration [A-580-807] Polyethylene Terephthalate Film, Sheet, and Strip...antidumping duty order on polyethylene terephthalate film, sheet, and strip...1\\ See Polyethylene Terephthalate Film, Sheet, and...

2011-11-18

320

76 FR 47546 - Polyethylene Terephthalate Film, Sheet, and Strip From India: Preliminary Results of Antidumping...  

Science.gov (United States)

...Administration [A-533-824] Polyethylene Terephthalate Film, Sheet, and Strip...antidumping duty order on polyethylene terephthalate film, sheet, and strip...Antidumping Duty Order: Polyethylene Terephthalate Film, Sheet, and...

2011-08-05

 
 
 
 
321

76 FR 72676 - Polyethylene Terephthalate Film, Sheet, and Strip From Brazil: Final Results of Antidumping Duty...  

Science.gov (United States)

...Administration [A-351-841] Polyethylene Terephthalate Film, Sheet, and Strip...antidumping duty order on polyethylene terephthalate film, sheet, and strip...parties to comment. See Polyethylene Terephthalate Film, Sheet, and...

2011-11-25

322

77 FR 3730 - Polyethylene Terephthalate Film, Sheet and Strip From India: Rescission, in Part, of Antidumping...  

Science.gov (United States)

...Administration [A-533-824] Polyethylene Terephthalate Film, Sheet and Strip...duty (AD) order on polyethylene terephthalate film, sheet and strip...September 20, 2011. See Polyethylene Terephthalate Film, Sheet and...

2012-01-25

323

77 FR 73428 - Polyethylene Terephthalate Film, Sheet, and Strip From the People's Republic of China...  

Science.gov (United States)

...Administration [A-570-924] Polyethylene Terephthalate Film, Sheet, and Strip...antidumping duty order on polyethylene terephthalate film, sheet, and strip...Administrative Review: Polyethylene Terephthalate Film, Sheet, and...

2012-12-10

324

78 FR 48143 - Polyethylene Terephthalate Film, Sheet, and Strip From India: Preliminary Results of Antidumping...  

Science.gov (United States)

...Administration [A-533-824] Polyethylene Terephthalate Film, Sheet, and Strip...antidumping duty order on polyethylene terephthalate film, sheet, and strip...Administrative Review: Polyethylene Terephthalate Film, Sheet, and...

2013-08-07

325

75 FR 14423 - Polyethylene Terephthalate Film, Sheet and Strip from Taiwan: Extension of Time Limit for...  

Science.gov (United States)

...Administration [A-583-837] Polyethylene Terephthalate Film, Sheet and Strip...antidumping duty order on polyethylene terephthalate film, sheet and strip...antidumping order on polyethylene terephthalate film, sheet and...

2010-03-25

326

78 FR 67113 - Polyethylene Terephthalate Film, Sheet and Strip From India and Taiwan: Preliminary Results of...  

Science.gov (United States)

...A-533-824, A-583-837] Polyethylene Terephthalate Film, Sheet and Strip...antidumping duty orders on Polyethylene Terephthalate Film, Sheet and Strip...Antidumping Duty Order: Polyethylene Terephthalate Film, Sheet, and...

2013-11-08

327

77 FR 19634 - Polyethylene Terephthalate Film, Sheet and Strip From India: Rescission of Countervailing Duty...  

Science.gov (United States)

...Administration [C-533-825] Polyethylene Terephthalate Film, Sheet and Strip...duty (CVD) order on polyethylene terephthalate film, sheet and strip...Vacmet and Polypacks. See Polyethylene Terephthalate Film, Sheet and...

2012-04-02

328

75 FR 40784 - Polyethylene Terephthalate Film, Sheet, and Strip from the Republic of Korea: Preliminary Results...  

Science.gov (United States)

...Administration [A-580-807] Polyethylene Terephthalate Film, Sheet, and Strip...antidumping duty order on polyethylene terephthalate film, sheet and strip...than July 7, 2010. See Polyethylene Terephthalate Film, Sheet and...

2010-07-14

329

75 FR 49900 - Polyethylene Terephthalate Film, Sheet, and Strip From Brazil: Preliminary Results of Antidumping...  

Science.gov (United States)

...Administration [A-351-841] Polyethylene Terephthalate Film, Sheet, and Strip...antidumping duty order on polyethylene terephthalate film, sheet, and strip...film from Brazil. See Polyethylene Terephthalate Film, Sheet, and...

2010-08-16

330

75 FR 6634 - Polyethylene Terephthalate Film, Sheet, and Strip from India: Final Results of Countervailing...  

Science.gov (United States)

...Administration [C-533-825] Polyethylene Terephthalate Film, Sheet, and Strip...countervailing duty order on polyethylene terephthalate film, sheet, and strip...December 31, 2007. See Polyethylene Terephthalate Film, Sheet, and...

2010-02-10

331

76 FR 76948 - Polyethylene Terephthalate Film, Sheet, and Strip From India: Final Results of Countervailing...  

Science.gov (United States)

...Administration [C-533-825] Polyethylene Terephthalate Film, Sheet, and Strip...administrative review of polyethylene terephthalate film, sheet and strip...Since the issuance of Polyethylene Terephthalate Film, Sheet, and...

2011-12-09

332

76 FR 61085 - Polyethylene Terephthalate Film, Sheet, and Strip From the People's Republic of China: Extension...  

Science.gov (United States)

...Administration [A-570-924] Polyethylene Terephthalate Film, Sheet, and Strip...administrative review of polyethylene terephthalate film, sheet, and strip...review by 60 days. See Polyethylene Terephthalate Film, Sheet, and...

2011-10-03

333

76 FR 57715 - Polyethylene Terephthalate Film, Sheet, and Strip From the Republic of Korea: Revocation of...  

Science.gov (United States)

...Administration [A-580-807] Polyethylene Terephthalate Film, Sheet, and Strip...antidumping duty order on polyethylene terephthalate film, sheet, and strip...antidumping duty order on polyethylene terephthalate film, sheet, and...

2011-09-16

334

75 FR 65450 - Polyethylene Terephthalate Film, Sheet and Strip From India: Extension of Time Limit for...  

Science.gov (United States)

...Administration [A-533-824] Polyethylene Terephthalate Film, Sheet and Strip...antidumping duty order on polyethylene terephthalate film, sheet and strip...December 31, 2009. See Polyethylene Terephthalate Film, Sheet and...

2010-10-25

335

76 FR 9745 - Polyethylene Terephthalate Film, Sheet, and Strip From Taiwan: Final Results of Antidumping Duty...  

Science.gov (United States)

...Administration [A-583-837] Polyethylene Terephthalate Film, Sheet, and Strip...antidumping duty order on polyethylene terephthalate film (PET Film) from Taiwan. See Polyethylene Terephthalate Film, Sheet, and...

2011-02-22

336

The Prebiotic Synthesis of Ethylenediamine Monoacetic Acid, The Repeating Unit of Peptide Nucleic Acids  

Science.gov (United States)

The polymerization of ribonucleic acids or their precursors constitutes an important event in prebiotic chemistry. The various problems using ribonucleotides to make RNA suggest that there may have been a precursor. An attractive possibility are the peptide nucleic acids (PNA). PNAs are nucleotide analogs that make use of a polymer of ethylenediamine monoacetic acid (EDMA or 2-amninoethyl glycine) with the bases attached by an acetic acid. EDMA is an especially attractive alternative to the ribose phosphate or deoxyribose phosphate backbone because it contains no chiral centers and is potentially prebiotic, but there is no reported prebiotic synthesis. We have synthesized both EDMA and ethylenediamine diacetic acid (EDDA) from the prebiotic compounds ethylenediamine, formaldehyde, and hydrogen cyanide. The yields of EDMA range from 11 to 79% along with some sEDDA and uEDDA. These reactions work with concentrations of 10(exp -1)M and as low as 10(exp -4)M, and the reaction is likely to be effective at even lower concentrations. Ethylenediamine is a likely prebiotic compound, but it has not yet been demonstrated, although compounds such as ethanolamine and cysteamine have been proven to be prebiotic. Under neutral pH and heating at l00 C, EDMA is converted to the lactam, monoketopiperazine (MKP). The cyclization occurs and has an approximate ratio of MKP/EDMA = 3 at equilibrium. We have measured the solubilities of EDMA center dot H20 as 6.4 m, EDMA center dot HCl center dot H20 as 13.7 m, and EDMA center dot 2HCl center dot H20 as 3.4 m. These syntheses together with the high solubility of EDMA suggest that EDMA would concentrate in drying lagoons and might efficiently form polymers. Given the instability of ribose and the poor polymerizability of nucleotides, the prebiotic presence of EDMA and the possibility of its polymerization raises the possibility that PNAs are the progenitors of present day nucleic acids. A pre-RNA world may have existed in which PNAs or polymers with related peptide backbones were the dominant information macromolecules.

Nelson, Kevin E.; Miller, Stanley L.

1992-01-01

337

Controlled change of transport properties of poly(ethylene terephthalate) track membranes by plasma method  

International Nuclear Information System (INIS)

A process of plasma polymerization of dimethylaniline and acrylic acid vapours on the surface of poly(ethylene terephthalate) track membranes has been investigated. The surface and hydrodynamic properties of the composite membranes produced in this case have been studied. It is shown that the water permeability of the obtained polymeric membranes can be controlled by changing the filtrate pH. Membranes with such properties can be used for controllable drug delivery and in sensor control

338

Electron beam induced modification of poly(ethylene terephthalate) films  

International Nuclear Information System (INIS)

Electron beam processing of poly(ethylene terephthalate) (PET) films is found to promote significant changes in the melting heat, intrinsic viscosity and polymer film-liquid (water, isooctane and toluene) boundary surface tension. These properties are featured with several maximums depending on the absorbed dose and correlating with the modification of PET surface functionality. Studies using adsorption of acid-base indicators and IR-spectroscopy revealed that the increase of PET surface hydrophilicity is determined by the oxidation of methylene and methyne groups. Electron beam treatment of PET films on the surface of N-vinylpyrrolidone aqueous solution provided graft copolymerization with this comonomer at optimum process parameters (energy 700 keV, current 1 mA, absorbed dose 50 kGy)

339

Theoretical investigations on the synthesis mechanism of cyanuric acid from NH? and CO?.  

Science.gov (United States)

In the synthesis of cyanuric acid from NH3 and CO2, urea and isocyanic acid OCNH are two pivotal intermediates. Based on density functional theory (DFT) calculations, the synthesis mechanism of cyanuric acid from NH3 + CO2 was investigated systematically. Urea can be synthesized from NH3 and CO2, and cyanuric acid can be obtained from urea or NH3 + CO2. In the stepwise mechanism of cyanuric acid from urea or NH3 + CO2, the energy barriers are relatively high, and the condition of high pressure and temperature does not decrease the energy barriers. Our theoretical model shows that cyanuric acid is actually acquired from OCNH via a one-step cycloaddition reaction. PMID:24077837

Cheng, Xueli; Zhao, Yanyun; Zhu, Weiqun; Liu, Yongjun

2013-11-01

340

Decreased hepatotoxic bile acid composition and altered synthesis in progressive human nonalcoholic fatty liver disease  

Energy Technology Data Exchange (ETDEWEB)

Bile acids (BAs) have many physiological roles and exhibit both toxic and protective influences within the liver. Alterations in the BA profile may be the result of disease induced liver injury. Nonalcoholic fatty liver disease (NAFLD) is a prevalent form of chronic liver disease characterized by the pathophysiological progression from simple steatosis to nonalcoholic steatohepatitis (NASH). The hypothesis of this study is that the ‘classical’ (neutral) and ‘alternative’ (acidic) BA synthesis pathways are altered together with hepatic BA composition during progression of human NAFLD. This study employed the use of transcriptomic and metabolomic assays to study the hepatic toxicologic BA profile in progressive human NAFLD. Individual human liver samples diagnosed as normal, steatosis, and NASH were utilized in the assays. The transcriptomic analysis of 70 BA genes revealed an enrichment of downregulated BA metabolism and transcription factor/receptor genes in livers diagnosed as NASH. Increased mRNA expression of BAAT and CYP7B1 was observed in contrast to decreased CYP8B1 expression in NASH samples. The BA metabolomic profile of NASH livers exhibited an increase in taurine together with elevated levels of conjugated BA species, taurocholic acid (TCA) and taurodeoxycholic acid (TDCA). Conversely, cholic acid (CA) and glycodeoxycholic acid (GDCA) were decreased in NASH liver. These findings reveal a potential shift toward the alternative pathway of BA synthesis during NASH, mediated by increased mRNA and protein expression of CYP7B1. Overall, the transcriptomic changes of BA synthesis pathway enzymes together with altered hepatic BA composition signify an attempt by the liver to reduce hepatotoxicity during disease progression to NASH. - Highlights: ? Altered hepatic bile acid composition is observed in progressive NAFLD. ? Bile acid synthesis enzymes are transcriptionally altered in NASH livers. ? Increased levels of taurine and conjugated bile acids are observed in NASH. ? Hepatic bile acid synthesis shifts toward the alternative pathway in NASH.

Lake, April D. [University of Arizona, Department of Pharmacology and Toxicology, Tucson, AZ 85721 (United States); Novak, Petr [Biology Centre ASCR, Institute of Plant Molecular Biology, Ceske Budejovice 37001 (Czech Republic); Shipkova, Petia; Aranibar, Nelly; Robertson, Donald; Reily, Michael D. [Pharmaceutical Candidate Optimization, Bristol-Myers Squibb Co., Princeton, NJ 08543 (United States); Lu, Zhenqiang [The Arizona Statistical Consulting Laboratory, University of Arizona, Tucson, AZ 85721 (United States); Lehman-McKeeman, Lois D. [Pharmaceutical Candidate Optimization, Bristol-Myers Squibb Co., Princeton, NJ 08543 (United States); Cherrington, Nathan J., E-mail: cherrington@pharmacy.arizona.edu [University of Arizona, Department of Pharmacology and Toxicology, Tucson, AZ 85721 (United States)

2013-04-15

 
 
 
 
341

Decreased hepatotoxic bile acid composition and altered synthesis in progressive human nonalcoholic fatty liver disease  

International Nuclear Information System (INIS)

Bile acids (BAs) have many physiological roles and exhibit both toxic and protective influences within the liver. Alterations in the BA profile may be the result of disease induced liver injury. Nonalcoholic fatty liver disease (NAFLD) is a prevalent form of chronic liver disease characterized by the pathophysiological progression from simple steatosis to nonalcoholic steatohepatitis (NASH). The hypothesis of this study is that the ‘classical’ (neutral) and ‘alternative’ (acidic) BA synthesis pathways are altered together with hepatic BA composition during progression of human NAFLD. This study employed the use of transcriptomic and metabolomic assays to study the hepatic toxicologic BA profile in progressive human NAFLD. Individual human liver samples diagnosed as normal, steatosis, and NASH were utilized in the assays. The transcriptomic analysis of 70 BA genes revealed an enrichment of downregulated BA metabolism and transcription factor/receptor genes in livers diagnosed as NASH. Increased mRNA expression of BAAT and CYP7B1 was observed in contrast to decreased CYP8B1 expression in NASH samples. The BA metabolomic profile of NASH livers exhibited an increase in taurine together with elevated levels of conjugated BA species, taurocholic acid (TCA) and taurodeoxycholic acid (TDCA). Conversely, cholic acid (CA) and glycodeoxycholic acid (GDCA) were decreased in NASH liver. These findings reveal a potential shift toward the alternative pathway of BA synthesis during NASH, mediated by increased mRNA and protein expression of CYP7B1. Overall, the transcriptomic changes of BA synthesis pathway enzymes together with altered hepatic BA composition signify an attempt by the liver to reduce hepatotoxicity during disease progression to NASH. - Highlights: ? Altered hepatic bile acid composition is observed in progressive NAFLD. ? Bile acid synthesis enzymes are transcriptionally altered in NASH livers. ? Increased levels of taurine and conjugated bile acids are observed in NASH. ? Hepatic bile acid synthesis shifts toward the alternative pathway in NASH

342

SYNTHESIS AND ANTIBACTERIAL ACTIVITY OF SCHIFF BASE DERIVATIVES OF 4-CHLORO-3-NITROBENZOIC ACID  

Digital Repository Infrastructure Vision for European Research (DRIVER)

4-chloro-3-nitrobenzoic acid was selected as nucleus structure having good antibacterial property. It was thought worthwhile to synthesize Schiff base derivatives of 4-chloro-3-nitrobenzoic acid in search of better antibacterial agents. The compounds were synthesized by first reducing nitro group in presence of Sn/HCl to 3-amino-4-chlorobenzoic acid, which on treatment with substituted benzaldehyde afforded the synthesis of the envisaged compounds. The synthesized compounds were purified and ...

Kumari Santosh; Singh Dharmchand Prasad

2012-01-01

343

Phenolic acids in the wild mushroom Ganoderma lucidum and synthesis of some possible metabolites.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Ganoderma lucidum is one of the most extensive!) studied mushrooms due to its medicinal properties, p-Hydroxybenzoic acid was the most abundant phenolic acid found in this mushroom. after HPLC-DAD-MS analysis. In the present work we describe the synthesis of glucuronide and methyl derivatives of p-hydroxybenzoic acid, which arc two of the main circulating metabolites found in humans. Their biological activity is going to be evaluated and compared to the parent compound in order...

Heleno, Sandrina A.; Ferreira, Isabel C. F. R.; Martins, Anabela; Esteves, Ana P.; Queiroz, Maria Joa?o R. P.

2012-01-01

344

Parallel Chemoenzymatic Synthesis of Sialosides Containing a C5-Diversified Sialic Acid  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A convenient chemoenzymatic strategy for synthesizing sialosides containing a C5-diversified sialic acid was developed. The ?2,3- and ?2,6-linked sialosides containing a 5-azido neuraminic acid synthesized by a highly efficient one-pot three-enzyme approach were converted to C5?-amino sialosides, which were used as common intermediates for chemical parallel synthesis to quickly generate a series of sialosides containing various sialic acid forms.

Cao, Hongzhi; Muthana, Saddam; Li, Yanhong; Cheng, Jiansong; Chen, Xi

2009-01-01

345

The Role of Benzoate in Anaerobic Degradation of Terephthalate  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The effects of acetate, benzoate, and periods without substrate on the anaerobic degradation of terephthalate (1,4-benzene-dicarboxylate) by a syntrophic methanogenic culture were studied. The culture had been enriched on terephthalate and was capable of benzoate degradation without a lag phase. When incubated with a mixture of benzoate and terephthalate, subsequent degradation with preference for benzoate was observed. Both benzoate and acetate inhibited the anaerobic degradation of terephth...

Kleerebezem, R.; Hulshoff Pol, L. W.; Lettinga, G.

1999-01-01

346

Synthesis and tissue biodistribution of [?-11C]palmitic acid. A novel PET imagining agent for cardiac fatty acid metabolism  

International Nuclear Information System (INIS)

In order to diagnose patients with medium-chain acyl-CoA dehydrogenase deficiency with a noninvasive diagnostic technique such as positron emission tomography, they have developed a synthesis of [?-11C]palmitic acid. The radiochemical synthesis was achieved by coupling an alkylfuran Grignard reagent (7) with [11C]methyl iodide, followed by rapid oxidative cleavage of the furan ring to the carboxylate using ruthenium tetraoxide. Tissue biodistribution studies in rags comparing [?-11C]palmitic acid and [1-11C]palmitic acid show that the %ID/g and %ID/organ in the heart tissue after administration of [?-11C]palmitic acid is approximately 50% greater than after administration of [1-11C]palmitic acid, due to the diminished metabolism of the [?-11C]palmitic acid. These studies show as well, low uptake in nontarget tissues (blood, lung, kidney, and muscle). PET images of a dog heart obtained after administration of [?-11C]- and [1-11C]palmitic acid show virtually identical uptake and distribution in the myocardium. The differing cardiac washout of labeled palmitates measured by dynamic PET studies may allow diagnosis of disorders in cardiac fatty acid metabolism

347

Current dependence on electrical field intensity and temperature in polyethylene terephthalate  

International Nuclear Information System (INIS)

This article is devoted to current dependence on electrical field intensity and temperature in polyethylene terephthalate. The processes of current passage in polyethylene terephthalate are described.

348

75 FR 53711 - Polyethylene Terephthalate (PET) Film From Korea  

Science.gov (United States)

...INTERNATIONAL TRADE COMMISSION [Investigation No. 731-TA-459 (Third Review)] Polyethylene Terephthalate (PET) Film From Korea AGENCY: United States International Trade Commission. ACTION: Institution of a...

2010-09-01

349

Depolymerization of polyethylene terephthalate in supercritical methanol  

Science.gov (United States)

The degradation of polyethylene terephthalate (PET) in supercritical methanol was investigated with the aim of developing a process for chemical recycling of waste plastics. A batch reactor was used at temperatures of 573-623 K under an estimated pressure of 20 MPa for a reaction time of 2-120 min. PET was decomposed to its monomers, dimethyl terephthalate and ethylene glycol, by methanolysis in supercritical methanol. The reaction products were analysed using size-exclusion chromatography, gas chromatography-mass spectrometry, and reversed-phase liquid chromatography. The molecular weight distribution of the products was obtained as a function of reaction time. The yields of monomer components of the decomposition products including by-products were measured. Continuous kinetics analysis was performed on the experimental data.

Goto, Motonobu; Koyamoto, Hiroshi; Kodama, Akio; Hirose, Tsutomu; Nagaoka, Shoji

2002-11-01

350

Synthesis and characterization of humic acids with distinct redox capacities  

International Nuclear Information System (INIS)

Various humic acids with distinct redox capacities were synthesized, based on the oxidation of hydroquinone in alkaline solution in the presence or absence of amino acids. The synthesized humic acids show Fe(III) redox capacities which are up to 10 times higher than that of natural humic acid from Aldrich. (orig.)

351

Immobilization of silver nanoparticles on polyethylene terephthalate  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Two different procedures of grafting with silver nanoparticles (AgNP) of polyethylene terephthalate (PET), activated by plasma treatment, are studied. In the first procedure, the PET foil was grafted with biphenyl-4,4?-dithiol and subsequently with silver nanoparticles. In the second one, the PET foil was grafted with silver nanoparticles previously coated with the same dithiol. X-ray photoelectron spectroscopy and electrokinetic analysis were used for characterization of the polymer surfac...

Reznickova, Alena; Novotna, Zdenka; Kolska, Zdenka; Svorcik, Vaclav

2014-01-01

352

Speciation of antimony in polyethylene terephthalate bottles  

International Nuclear Information System (INIS)

Antimony contamination has been reported in drinking water from polyethylene terephthalate (PET) bottles. Micro-X-ray fluorescence (XRF) analysis has been used to identify the distribution and chemical form of residual antimony used as a catalyst in the manufacture of PET bottles. The results are consistent with clusters of Sb(III) having dimensions of the order of tens of micrometers, clearly showing the ability of synchrotron radiation analyses to both map elemental distribution and determine oxidation state.

353

Speciation of antimony in polyethylene terephthalate bottles  

Energy Technology Data Exchange (ETDEWEB)

Antimony contamination has been reported in drinking water from polyethylene terephthalate (PET) bottles. Micro-X-ray fluorescence (XRF) analysis has been used to identify the distribution and chemical form of residual antimony used as a catalyst in the manufacture of PET bottles. The results are consistent with clusters of Sb(III) having dimensions of the order of tens of micrometers, clearly showing the ability of synchrotron radiation analyses to both map elemental distribution and determine oxidation state.

Martin, R.R.; Ablett, J.; Shotyk, W.S.; Naftel, S.; Northrup, P.

2009-12-18

354

Synthesis and Hydrolytic Degradation of Substituted Poly(DL-Lactic Acid)s  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Non-substituted racemic poly(DL-lactic acid) (PLA) and substituted racemic poly(DL-lactic acid)s or poly(DL-2-hydroxyalkanoic acid)s with different side-chain lengths, i.e., poly(DL-2-hydroxybutanoic acid) (PBA), poly(DL-2-hydroxyhexanoic acid) (PHA), and poly(DL-2-hydroxydecanoic acid) (PDA) were synthesized by acid-catalyzed polycondensation of DL-lactic acid (LA), DL-2-hydroxybutanoic acid (BA), DL-2-hydroxyhexanoic acid (HA), and DL-2-hydroxydecanoic acid (DA), respectively. The hydrolyti...

Hideto Tsuji; Takehiko Eto; Yuzuru Sakamoto

2011-01-01

355

Furan fatty acids: occurrence, synthesis, and reactions. Are furan fatty acids responsible for the cardioprotective effects of a fish diet?  

Science.gov (United States)

Furan FA (F-acids) are tri- or tetrasubstituted furan derivatives characterized by either a propyl or pentyl side chain in one of the alpha-positions; the other is substituted by a straight long-chain saturated acid with a carboxylic group at its end. F-acids are generated in large amounts in algae, but they are also produced by plants and microorganisms. Fish and other marine organisms as well as mammals consume F-acids in their food and incorporate them into phospholipids and cholesterol esters. F-acids are catabolized to dibasic urofuran acids, which are excreted in the urine. The biogenetic precursor of the most abundant F-acid, F6, is linoleic acid. Methyl groups in the beta-position are derived from adenosylmethionine. Owing to the different alkyl substituents, synthesis of F-acids requires multistep reactions. F-acids react readily with peroxyl radicals to generate dioxoenes. The radical-scavenging ability of F-acids may contribute to the protective properties of fish and fish oil diets against mortality from heart disease. PMID:16296395

Spiteller, Gerhard

2005-08-01

356

Regulation of Polyglutamic Acid Synthesis by Glutamate in Bacillus licheniformis and Bacillus subtilis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The synthesis of polyglutamic acid (PGA) was repressed by exogenous glutamate in strains of Bacillus licheniformis but not in strains of Bacillus subtilis, indicating a clear difference in the regulation of synthesis of capsular slime in these two species. Although extracellular ?-glutamyltranspeptidase (GGT) activity was always present in PGA-producing cultures of B. licheniformis under various growth conditions, there was no correlation between the quantity of PGA and enzyme activity. More...

Kambourova, Margarita; Tangney, Martin; Priest, Fergus G.

2001-01-01

357

Synthesis of Boron Carbide from Boric Acid and Carbon-Containing Precursors  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The paper compares low-temperature techniques for boron carbide synthesis. Boron carbide was syn-thesized via reaction between boric acid and various carbon precursors, e.g. phenol-formaldehyde resin, su-crose, carbon black, and potato starch. Initial compositions and carbon precursor preparation techniques were selected for synthesis. The resulting products were characterized by IR spectrometry, X-ray diffrac-tion (XRD) and scanning electron microscopy. Possible boron carbide yields up to 95...

Genusova T.N.; Zakharova K.; Mednikova A.; Rumyantsev V.

2013-01-01

358

Synthesis and proteasome inhibition of lithocholic acid derivatives.  

Science.gov (United States)

A new class of proteasome inhibitors was synthesized using lithocholic acid as a scaffold. Modification at the C-3 position of lithocholic acid with a series of acid acyl groups yielded compounds with a range of potency on proteasome inhibition. Among them, the phenylene diacetic acid hemiester derivative (13) displayed the most potent proteasome inhibition with IC(50) = 1.9 ?M. Enzyme kinetic analysis indicates that these lithocholic acid derivatives are noncompetitive inhibitors of the proteasome. PMID:21388808

Dang, Zhao; Lin, Andrew; Ho, Phong; Soroka, Dominique; Lee, Kuo-Hsiung; Huang, Li; Chen, Chin-Ho

2011-04-01

359

Synthesis and proteasome inhibition of lithocholic acid derivatives  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A new class of proteasome inhibitors was synthesized using lithocholic acid as a scaffold. Modification at the C-3 position of lithocholic acid with a series of acid acyl groups yielded compounds with a range of potency on proteasome inhibition. Among them, the phenylene diacetic acid hemiester derivative (13) displayed the most potent proteasome inhibition with IC50 = 1.9 ?M. Enzyme kinetic analysis indicates that these lithocholic acid derivatives are non-competitive inhibitors of the prot...

Dang, Zhao; Lin, Andrew; Ho, Phong; Soroka, Dominique; Lee, Kuo-hsiung; Huang, Li; Chen, Chin-ho

2011-01-01

360

Solvent-free lipase-catalyzed synthesis of a novel hydroxyl-fatty acid derivative of kojic acid.  

Science.gov (United States)

The aim of this work was the synthesis of a novel hydroxyl-fatty acid derivative of kojic acid rich in kojic acid monoricinoleate (KMR) which can be widely used in the cosmetic and food industry. The synthesis of KMR was carried out by lipase-catalysed esterification of ricinoleic and kojic acids in solvent-free system. Three immobilized lipases were tested and the best KMR yields were attained with Lipozyme TL IM and Novozym 435. Since Lipozyme TL IM is the cheapest, it was selected to optimize the reaction conditions. The optimal reaction conditions were 80 °C for the temperature, 1:1 for the alcohol/acid molar ratio, 600 rpm for stirring speed and 7.8% for the catalyst concentration. Under these conditions, the reaction was scaled up in a 5×10?³ m³ stirred tank reactor. ¹H-¹³C HMBC-NMR showed that the primary hydroxyl group of kojic acid was regioselectively esterified. The KMR has more lipophilicity than kojic acid and showed antioxidant activity that improves the oxidation stability of biodiesel. PMID:24411455

El-Boulifi, Noureddin; Ashari, Siti Efliza; Serrano, Marta; Aracil, Jose; Martínez, Mercedes

2014-02-01

 
 
 
 
361

New hydroxamic acid derivatives of fluoroquinolones: synthesis and evaluation of antibacterial and anticancer properties.  

Science.gov (United States)

A series of new hydroxamic acid derivatives (6a-f) at C-3 position of fluoroquinolones were designed and synthesized through multistep synthesis. The design concept involved replacement of the 3-carboxylic acid in fluoquinolones with hydroxamic acid as an acid mimicking group. The synthetic work employed in this work provides a good example for the synthesis of pure hydroxamic acid based fluoroquinolones. The synthesized compounds were characterized by (1)H-NMR, electrospray ionization (ESI)-MS and IR. The new compounds were tested for their in vitro antimicrobial and anti-proliferative activity. Out of the six derivatives, compound 6e exhibited moderate antibacterial activity by inhibiting the growth of Escherichia coli and Klebsiella pneumoniae (MIC: 4.00-8.00 µg/mL). Compounds 6b and 6f displayed good growth inhibition against A549 Lung adenocarcinoma and HCT-116 Colon carcinoma cell lines. PMID:24270473

Rajulu, Gavara Govinda; Bhojya Naik, Halehatty Seephya; Viswanadhan, Abhilash; Thiruvengadam, Jayaraman; Rajesh, Kondodiyil; Ganesh, Sambasivam; Jagadheshan, Hiriyan; Kesavan, Poonimangadu Koppolu

2014-01-01

362

Receptor-mediated uptake of low density lipoprotein stimulates bile acid synthesis by cultured rat hepatocytes  

International Nuclear Information System (INIS)

The cellular mechanisms responsible for the lipoprotein-mediated stimulation of bile acid synthesis in cultured rat hepatocytes were investigated. Adding 280 micrograms/ml of cholesterol in the form of human or rat low density lipoprotein (LDL) to the culture medium increased bile acid synthesis by 1.8- and 1.6-fold, respectively. As a result of the uptake of LDL, the synthesis of [14C]cholesterol from [2-14C]acetate was decreased and cellular cholesteryl ester mass was increased. Further studies demonstrated that rat apoE-free LDL and apoE-rich high density lipoprotein (HDL) both stimulated bile acid synthesis 1.5-fold, as well as inhibited the formation of [14C]cholesterol from [2-14C]acetate. Reductive methylation of LDL blocked the inhibition of cholesterol synthesis, as well as the stimulation of bile acid synthesis, suggesting that these processes require receptor-mediated uptake. To identify the receptors responsible, competitive binding studies using 125I-labeled apoE-free LDL and 125I-labeled apoE-rich HDL were performed. Both apoE-free LDL and apoE-rich HDL displayed an equal ability to compete for binding of the other, suggesting that a receptor or a group of receptors that recognizes both apolipoproteins is involved. Additional studies show that hepatocytes from cholestyramine-treated rats displayed 2.2- and 3.4-fold increases in the binding of apoE-free LDL and apoE-rich HDL, respectively. These data show for the first time that receptor-mediated uptake ofirst time that receptor-mediated uptake of LDL by the liver is intimately linked to processes activating bile acid synthesis

363

Aqueous Microwave-Assisted Solid-Phase Synthesis Using Boc-Amino Acid Nanoparticles  

Directory of Open Access Journals (Sweden)

Full Text Available We have previously developed water-based microwave (MW-assisted peptide synthesis using Fmoc-amino acid nanopaticles. It is an organic solvent-free, environmentally friendly method for peptide synthesis. Here we describe water-based MW-assisted solid-phase synthesis using Boc-amino acid nanoparticles. The microwave irradiation allowed rapid solid-phase reaction of nanoparticle reactants on the resin in water. We also demonstrated the syntheses of Leu-enkephalin, Tyr-Gly-Gly-Phe-Leu-OH, and difficult sequence model peptide, Val-Ala-Val-Ala-Gly-OH, using our water-based MW-assisted protocol with Boc-amino acid nanoparticles.

Yoshinobu Fukumori

2013-07-01

364

Synthesis of [18-14C]octatriacontane from [1-14C]stearic acid  

International Nuclear Information System (INIS)

A method was developed to synthesize 14C-labelled n-alkanes for use in cigarette smoke studies. Specifically, n-[18-14C]-octatriacontane was synthesized from 1 mCi [1-14C]stearic acid in a radiochemical yield of 20%. The key features of this synthesis were two consecutive alkylations of tosylmethyl isocyanide followed by acid hydrolysis to [18-14C]-19-octatriacontanone and modified Wolff-Kishner reduction to the n-alkane. After purification on silica gel 25 mg of [18-14C]octatriacontane was obtained with a total radioactivity of 200 ?Ci, a specific activity of 4.3 mCi/mmol, and a radiochemical purity in excess of 98% by thin layer radiochromatography. The method has also been applied to the synthesis of unlabeled n-pentatriacontane and is considered to be generally applicable to the synthesis of radiolabeled alkanes from radiolabeled fatty acids. (author)

365

Peptide nucleic acids: structure, properties, applications, strategies and practice of chemical synthesis  

International Nuclear Information System (INIS)

The information on the structure and properties of peptide nucleic acids (PNA) is generalised. The use of PNA oligomers in biomolecular studies and biotechnology is exemplified. The published data on the most important methods for the chemical synthesis of PNA oligomers with the main emphasis on the efficiency of condensation reactions are considered. The methods for PNA synthesis are systematised; their advantages and disadvantages are discussed. Some recommendations for optimisation of the condensation procedure and synthesis of PNA are presented. The bibliography includes 153 references.

366

Early effects of dietary orotic acid upon liver lipid synthesis and bile cholesterol secretion in rats  

International Nuclear Information System (INIS)

Dietary orotic acid is known to cause impaired fatty acid synthesis and increased cholesterol synthesis in rats. The authors found that the impaired fatty acid synthesis occurs during the first day of orotic acid feeding and, in studies with albumin-bound [1-14C]palmitic acid, an associated decrease in the rate of esterification of this fatty acid into triacylglycerol, phospholipid, and cholesteryl ester was observed. These changes may result from the known decreases in liver levels of adenine nucleotides or, as reported here, from decreased liver CoASH levels in orotic acid-fed rats. The increase in hepatic cholesterol synthesis occurred during the second day of orotic acid feeding. It was detected by increased incorporation of [1,2-14C]acetate into cholesterol by liver slices and by a 7-fold increase in HMG-CoA reductase activity. At the same time the biliary output of cholesterol was increased 2-fold and studies using 3H2O revealed that the output of newly synthesized cholesterol in bile was increased 5-fold. The content of cholesteryl ester in hepatic microsomes decreased during orotic acid feeding but free cholesterol was unchanged. The findings are interpreted to suggest that the increased bile cholesterol secretion caused by orotic acid is a result of impaired hepatic cholesterol esterification and that the increase in HMG-CoA reductase activity is a result of diminished negative feedback due to the depleted content oive feedback due to the depleted content of cholesteryl ester in the hepatic microsomes

367

Water stress and protein synthesis. II. Interaction between water stress, hydrostatic pressure, and abscisic acid on the pattern of protein synthesis in Avena coleoptiles  

Energy Technology Data Exchange (ETDEWEB)

Water stress causes a reduction in hydrostatic pressure and can cause an increase in abscisic acid in plant tissues. To assess the possible role of abscisic acid and hydrostatic pressure in water stress effects, we have compared the effects of water stress, abscisic acid, and an imposed hydrostatic pressure on the rate and pattern of protein synthesis in Avena coleoptiles. Water stress reduces the rate and changes the pattern of protein synthesis as judged by a double labeling ratio technique. Abscisic acid reduces the rate but does not alter the pattern of protein synthesis. Gibberellic acid reverses the abscisic acid-induced but not the stress-induced inhibition of protein synthesis. The effect of hydrostatic pressure depends on the gas used. With a 19:1 N/sub 2/-air mixture, the rate of protein synthesis is increased in stressed but not in turgid tissues. An imposed hydrostatic pressure alters the pattern of synthesis in stressed tissues, but does not restore the pattern to that found in turgid tissues. Because of the differences in response, we conclude that water stress does not affect protein synthesis via abscisic acid or reduced hydrostatic pressure. (auth)

Dhindsa, R.S.; Cleland, R.E.

1975-04-01

368

Biotin-functionalized poly(ethylene terephthalate) capillary-channeled polymer fibers as HPLC stationary phase for affinity chromatography.  

Science.gov (United States)

Native poly(ethylene terephthalate) (PET) capillary-channeled polymer (C-CP) fibers have been used as the stationary phase for high-performance liquid chromatography (HPLC) of proteins via reversed-phase and ion-exchange processes. Functionalization can be used to bring about greater selectivity through surface modification. PET fibers were treated with ethylenediamine to generate primary amine groups on the fiber surface, enabling subsequent covalent attachment of ligands. The ninhydrin test for primary amines revealed surface densities of 13.9-60.0 ?mol m(-2) for PET fibers exposed for periods of 3-12 min. Here, 8-amino-3,6-dioxaoctanoic acid was linked to the EDA-treated PET fiber surface as a hydrophilic spacer, and then D-biotin was attached on the end of the spacer as an affinity ligand. The streptavidin binding capacity and binding homogeneity were studied on the biotin-functionalized PET C-CP fiber microbore column. The selectivity of the biotin surface functionalization was assessed by spiking lysate with Texas Red-labeled streptavidin and enhanced green fluorescent protein. Greater than 99 % selectivity was realized. This ligand-coupling strategy from standard solid-phase peptide synthesis used in stationary phase functionalization creates great potential for PET C-CP fiber-packed HPLC columns to perform a variety of chromatographic separations. PMID:25410640

Jiang, Liuwei; Marcus, R Kenneth

2014-11-20

369

Camphor Sulfonic Acid-hydrochloric Acid Codoped Polyaniline/polyvinyl Alcohol Composite: Synthesis and Characterization  

Scientific Electronic Library Online (English)

Full Text Available SciELO Mexico | Language: English Abstract in spanish Se utilizó un sistema de dopaje complementario formado por ácido clorhídrico y ácido canforsulfónico (ACS) en la síntesis in-situ de un material compuesto polianilina (PANI)/alcohol polivi-nílico (APV). Las mediciones de conductividad mostraron que el uso de ACS ya sea como dopante o codopante resul [...] tó en un decremento en la conductividad total de hasta 2 órdenes de magnitud así como una mejora en la estabilidad térmica. Los compósitos PANi/APV fueron caracterizados mediante análisis térmicos y espectroscópicos. La formación de la sal esmeraldina conductora fue confirmada por espectroscopia UV-Visible e Infrarroja de Transformada de Fourier. El análisis microestructural se llevó a cabo por MEB. Abstract in english A complementary dopant system formed by hydrochloric and camphor sulfonic (CSA) acids was used in the in-situ synthesis of a polyaniline (PANi)/polyvinyl alcohol (PVA) composite. The conductivity measurements showed that the use of CSA either as single dopant or codopant caused a decrement up to 2 o [...] rders of magnitude on the overall conductivity as well as an improvement on thermal stability. The PANi/PVA composites were characterized by spectro-scopic and thermal analysis. Conducting emeraldine salt formation was confirmed by UV-VIS and FTIR spectroscopy. Microstructure analysis was performed by SEM imaging.

Jorge Enrique, Osorio-Fuente; Carlos, Gómez-Yáñez; María de los Ángeles, Hernández-Pérez; Fidel, Pérez-Moreno.

2014-03-01

370

Communic Acids: Occurrence, Properties and Use as Chirons for the Synthesis of Bioactive Compounds  

Directory of Open Access Journals (Sweden)

Full Text Available Communic acids are diterpenes with labdane skeletons found in many plant species, mainly conifers, predominating in the genus Juniperus (fam. Cupresaceae. In this review we briefly describe their distribution and different biological activities (anti- bacterial, antitumoral, hypolipidemic, relaxing smooth muscle, etc.. This paper also includes a detailed explanation of their use as chiral building blocks for the synthesis of bioactive natural products. Among other uses, communic acids have proven useful as chirons for the synthesis of quassinoids (formal, abietane antioxidants, ambrox and other perfume fixatives, podolactone herbicides, etc., featuring shorter and more efficient processes.

Alejandro F. Arteaga

2012-02-01

371

A convenient procedure for the solid-phase synthesis of hydroxamic acids on PEGA resins  

DEFF Research Database (Denmark)

An efficient method for the solid-phase synthesis of hydroxamic acids is described. The method comprises the nucleophilic displacement of esters immobilized on PEGA resins with hydroxylamine/sodium hydroxide in isopropanol. The hydroxyaminolysis protocol is compatible with a broad range of PEGA-supported peptide and peptidomimetic esters. The methodology was found to be compatible with two new strategies for the synthesis of solid-supported lactams and diketopiperazines, respectively, both relying on the high inter- and intramolecular reactivity of cyclic N-acyliminium ions with electron-rich aromatics and heteroaromatics, ultimately affording hydroxamic acid derivatives in high purities.

Nandurkar, Nitin Subhash; Petersen, Rico

2011-01-01

372

Amino-acid-assisted synthesis and size-dependent magnetic behaviors of hematite nanocubes  

Science.gov (United States)

This article reports the amino-acid-assisted synthesis and size-dependent magnetic properties of hematite nanocubes. The products were characterized using x-ray diffraction, Raman spectroscopy, transmission electron microscopy (TEM), and high-resolution TEM. The magnetic behavior of hematite nanocubes was studied using a vibrating sample magnetometer at room temperature. The sizes of hematite nanocubes were controlled by tuning the reaction parameters. The amino acid has double-hydrophilic functional groups, -NH2 and -COOH, which are utilized to control the growth and final size of hematite nanocubes. We show that utilizing biomolecules in chemical synthesis is a useful method for tailoring the physical properties of nanomaterials.

Cao, Huaqiang; Wang, Guozhi; Warner, Jamie H.; Watt, Andrew A. R.

2008-01-01

373

Communic acids: occurrence, properties and use as chirons for the synthesis of bioactive compounds.  

Science.gov (United States)

Communic acids are diterpenes with labdane skeletons found in many plant species, mainly conifers, predominating in the genus Juniperus (fam. Cupresaceae). In this review we briefly describe their distribution and different biological activities (anti- bacterial, antitumoral, hypolipidemic, relaxing smooth muscle, etc.). This paper also includes a detailed explanation of their use as chiral building blocks for the synthesis of bioactive natural products. Among other uses, communic acids have proven useful as chirons for the synthesis of quassinoids (formal), abietane antioxidants, ambrox and other perfume fixatives, podolactone herbicides, etc., featuring shorter and more efficient processes. PMID:22310167

Barrero, Alejandro F; Herrador, M Mar; Arteaga, Pilar; Arteaga, Jesús F; Arteaga, Alejandro F

2012-01-01

374

Amino acids augment muscle protein synthesis in neonatal pigs during acute endotoxemia by stimulating mTOR-dependent translation initiation  

Science.gov (United States)

In skeletal muscle of adults, sepsis reduces protein synthesis by depressing translation initiation and induces resistance to branched-chain amino acid stimulation. Normal neonates maintain a high basal muscle protein synthesis rate that is sensitive to amino acid stimulation. In the present study...

375

UV- and {gamma}-sensitization of latent tracks in polyethylene terephthalate  

Energy Technology Data Exchange (ETDEWEB)

Photosensitization of polymer polyethylene terephthalate (PET) bombarded with swift heavy ions (Xe) was studied. Ultraviolet (UV)- and {gamma}-irradiation were used for sensitization. Infrared spectroscopy (IR) and reversed-phase high-performance liquid chromatography (HPLC) were used to study the radiolysis products in latent tracks (directly in the sample or in the etching solution). It was found that the exposure of the sample to ultraviolet light results in the transformation of the radiolysis products formed in the tracks into terephthalic acid. Surface defects, detected by AFM, were found to correspond to tracks; their form (cavities and hillocks) and size changing reflect the changing of latent track state. It was found that UV irradiation destroyed the cross-linked regions in the tracks. This process (photodecomposition) was shown to be the key stage of the UV sensitization and the main cause of etching rate increase. The {gamma}-irradiation effect on track etching was found to be almost the same.

Vilensky, A.I.; Zagorski, D.L. E-mail: mic@eimb.ru; Kabanov, V.Ya.; Mchedlishvili, B.V

2003-06-01

376

Synthesis of novel C4-modified sialic acid analogues  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Sialic acids are a family of structurally-unique 9-carbon ?-keto acid sugars that are often found on the termini of oligosaccharide chains on glycoproteins and cell surfaces. These sugars can be removed through sialidases-catalyzed hydrolysis and play a number of roles in biological recognition events, serving as receptor sites for sialic acid-recognizing proteins and masking other antigenic oligosaccharides. The influenza virus recognizes sialic acids on cell surfaces of the upper respi...

Hemeon, Ivan William

2007-01-01

377

MAFG Is a Transcriptional Repressor of Bile Acid Synthesis and Metabolism.  

Science.gov (United States)

Specific bile acids are potent signaling molecules that modulate metabolic pathways affecting lipid, glucose and bile acid homeostasis, and the microbiota. Bile acids are synthesized from cholesterol in the liver, and the key enzymes involved in bile acid synthesis (Cyp7a1, Cyp8b1) are regulated transcriptionally by the nuclear receptor FXR. We have identified an FXR-regulated pathway upstream of a transcriptional repressor that controls multiple bile acid metabolism genes. We identify MafG as an FXR target gene and show that hepatic MAFG overexpression represses genes of the bile acid synthetic pathway and modifies the biliary bile acid composition. In contrast, loss-of-function studies using MafG(+/-) mice causes de-repression of the same genes with concordant changes in biliary bile acid levels. Finally, we identify functional MafG response elements in bile acid metabolism genes using ChIP-seq analysis. Our studies identify a molecular mechanism for the complex feedback regulation of bile acid synthesis controlled by FXR. PMID:25651182

de Aguiar Vallim, Thomas Q; Tarling, Elizabeth J; Ahn, Hannah; Hagey, Lee R; Romanoski, Casey E; Lee, Richard G; Graham, Mark J; Motohashi, Hozumi; Yamamoto, Masayuki; Edwards, Peter A

2015-02-01

378

Synthesis of alpha-hydroxyphosphonic acids from Lesquerella oil  

Science.gov (United States)

Lesquerella oil has been a substance of growing chemical interest, due to the ease with which it is produced and its similarity in structure to castor oil. The primary fatty acid in Lesquerella oil, lesquerolic acid, is very similar to the principal component of castor oil, ricinoleic acid, and may ...

379

Kinetics of Ethyl Acetate Synthesis Catalyzed by Acidic Resins  

Science.gov (United States)

A low-cost experiment to carry out the second-order reversible reaction of acetic acid esterification with ethanol to produce ethyl acetate is presented to illustrate concepts of kinetics and reactor modeling. The reaction is performed in a batch reactor, and the acetic acid concentration is measured by acid-base titration versus time. The…

Antunes, Bruno M.; Cardoso, Simao P.; Silva, Carlos M.; Portugal, Ines

2011-01-01

380

Racemic synthesis and solid phase peptide synthesis application of the chimeric valine/leucine derivative 2-amino-3,3,4-trimethyl-pentanoic acid.  

Science.gov (United States)

The synthesis of non natural amino acid 2-amino-3,3,4-trimethyl-pentanoic acid (Ipv) ready for solid phase peptide synthesis has been developed. Copper (I) chloride Michael addition, followed by a Curtius rearrangement are the key steps for the lpv synthesis. The racemic valine/leucine chimeric amino acid was then successfully inserted in position 5 of neuropeptide S (NPS) and the diastereomeric mixture separated by reverse phase HPLC. The two diastereomeric NPS derivatives were tested for intracellular calcium mobilization using HEK293 cells stably expressing the mouse NPS receptor where they behaved as partial agonist and pure antagonist. PMID:25073393

Pelà, M; Del Zoppo, L; Allegri, L; Marzola, E; Ruzza, C; Calo, G; Perissutti, E; Frecentese, F; Salvadori, S; Guerrini, R

2014-07-01

 
 
 
 
381

Effects of acetylsalicylic acid and paracetamol alone and in combination on prostanoid synthesis in man.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

1. The present study was designed to investigate the effects of acetylsalicylic acid and paracetamol given separately and in combination on total body and renal PGE2 synthesis in healthy volunteers. 2. In a randomized four-way cross-over study eleven female volunteers received for two consecutive days 3 g day-1 acetylsalicylic acid or 3 g day-1 paracetamol or a combination of 1.5 g day-1 acetylsalicylic acid and 1.5 g day-1 paracetamol, or 1.5 g day-1 acetylsalicylic acid separated by washout...

Bippi, H.; Fro?lich, J. C.

1990-01-01

382

Synthesis of aliphatic polyesters by polycondensation using inorganic acid as catalyst  

Digital Repository Infrastructure Vision for European Research (DRIVER)

An effective route for the synthesis of aliphatic polyesters made from adipic or sebacic acid and alkanediols, using inorganic acid as a catalyst is reported. The monomer composition, reaction time, catalyst type, and reaction conditions were optimized to yield polyesters with weight average molecular weights of 23,000 for adipic acid and 85,000 for sebacic acid-based polyesters. The polymers melt at temperatures of 52–65°C and possess melt viscosity in the range of 5600–19,400cP. This r...

Sokolsky-papkov, Marina; Langer, Robert; Domb, Abraham J.

2009-01-01

383

Synthesis and antimycobacterial evaluation of new trans-cinnamic acid hydrazide derivatives.  

Science.gov (United States)

In this work, we report the synthesis and the antimycobacterial evaluation of new trans-cinnamic acid derivatives of isonicotinic acid series (5) and benzoic acid series (6), designed by exploring the molecular hybridization approach between isoniazid (1) and trans-cinnamic acid derivative (3). The minimum inhibitory concentration (MIC) of the compounds 5a-d and 6c exhibited activity between 3.12 and 12.5 microg/mL and could be a good start point to find new lead compounds against multi-drug resistant tuberculosis. PMID:18068364

Carvalho, Samir A; da Silva, Edson F; de Souza, Marcus V N; Lourenço, Maria C S; Vicente, Felipe R

2008-01-15

384

Relationship of lipogenic enzyme activities to the rate of rat liver fatty acid synthesis  

International Nuclear Information System (INIS)

The mechanism by which diet regulates liver lipogenesis is unclear. Here the authors report how dietary alterations effect the activities of key enzymes of fatty acid (FA) synthesis. Male Sprague-Dawley rats, 400-500 g, were fasted for 48h and then refed a fat-free, high carbohydrate (HC) diet (75% cal. from sucrose) for 0,3,9,24 and 48h, or refed a HC diet for 48h, then fed a high-fat (HF) diet (44% cal. from corn oil) for 3,9,24 and 48h. The FA synthesis rate and the activities of acetyl CoA carboxylase (AC), fatty acid synthase (FAS), ATP citrate lyase (CL), and glucose 6-phosphate dehydrogenase (G6PDH) were determined in the livers. FA synthesis was assayed with 3H2O, enzyme activities were measured spectrophotometrically except for AC which was assayed with 14C-bicarbonate. There was no change in the activity of AC during fasting or on the HC diet. Fasting decreased the rate of FA synthesis by 25% and the activities of FAS and CL by 50%; refeeding the HC diet induced parallel changes in FA synthesis and the activities of FAS, CL, and G6PDH. After 9h on the HF diet, FA synthesis had decreased sharply, AC activity increased significantly while no changes were detected in the other activities. Subsequently FA synthesis did not change while the activities of the enzymes decreased slowly. These enzymes did not appear to regulate FA synthesis during inhibition of lipogenesis, but FAS, CL or G6PDH may be rate limiting in the induction phase. Other key factors may regulate FA synthesis during dietary alterations

385

Relationship of lipogenic enzyme activities to the rate of rat liver fatty acid synthesis  

Energy Technology Data Exchange (ETDEWEB)

The mechanism by which diet regulates liver lipogenesis is unclear. Here the authors report how dietary alterations effect the activities of key enzymes of fatty acid (FA) synthesis. Male Sprague-Dawley rats, 400-500 g, were fasted for 48h and then refed a fat-free, high carbohydrate (HC) diet (75% cal. from sucrose) for 0,3,9,24 and 48h, or refed a HC diet for 48h, then fed a high-fat (HF) diet (44% cal. from corn oil) for 3,9,24 and 48h. The FA synthesis rate and the activities of acetyl CoA carboxylase (AC), fatty acid synthase (FAS), ATP citrate lyase (CL), and glucose 6-phosphate dehydrogenase (G6PDH) were determined in the livers. FA synthesis was assayed with /sup 3/H/sub 2/O, enzyme activities were measured spectrophotometrically except for AC which was assayed with /sup 14/C-bicarbonate. There was no change in the activity of AC during fasting or on the HC diet. Fasting decreased the rate of FA synthesis by 25% and the activities of FAS and CL by 50%; refeeding the HC diet induced parallel changes in FA synthesis and the activities of FAS, CL, and G6PDH. After 9h on the HF diet, FA synthesis had decreased sharply, AC activity increased significantly while no changes were detected in the other activities. Subsequently FA synthesis did not change while the activities of the enzymes decreased slowly. These enzymes did not appear to regulate FA synthesis during inhibition of lipogenesis, but FAS, CL or G6PDH may be rate limiting in the induction phase. Other key factors may regulate FA synthesis during dietary alterations.

Nelson, G.; Kelley, D.; Schmidt, P.; Virk, S.; Serrato, C.

1986-05-01

386

Single-layered porous silica films on polyethylene terephthalate substrates for antireflection coatings  

International Nuclear Information System (INIS)

Single-layered porous silica films were prepared on polyethylene terephthalate (PET) substrates as antireflection coatings for efficient, large-scale flexible optoelectronic devices. Cetyltrimethylammonium bromide (CTAB)-templated synthesis was employed to form porous silica films. Without using high temperature treatment, CTAB was removed by washing in water to create a porous structure in the films. To spin-coat on PET substrates, contact angle between silica sol and PET surface was measured to optimize the molar ratio of the solution. Pore size and surface sharpness were estimated using atomic force microscope data. The average reflectance of as-prepared AR coatings on PET substrates was ? 2%.

387

Scientific Opinion on the safety evaluation of the active substances, terephthalic acid, dimethyl ester , polymer with 1,4-butanediol, cyclized, polymers with glycidyl methacrylate, hydroxyl-terminated polybutadiene, methyl methacrylate and styrene, and cobalt stearate for use in food contact materials  

Directory of Open Access Journals (Sweden)

Full Text Available

This scientific opinion of EFSA deals with the safety evaluation of the oxygen absorber (terephthalic acid, dimethyl ester, polymer with 1,4-butanediol, cyclized, polymers with glycidyl methacrylate, hydroxyl-terminated polybutadiene, methyl methacrylate and styrene copolymer (CAS No 1223402-34-3, FCM substance No 1005 and the oxidation catalyst cobalt stearate (CAS No 1002-88-6 and FCM Substance No 1004, intended to be used up to a maximum percentage of 1% in polyethylene terephtalate (PET for absorbing oxygen from the food environment. All starting substances of the oxygen absorber formulation and cobalt stearate have been evaluated and approved for use as additives in plastic food contact materials. Methyl methacrylate, glycidyl methacrylate and cobalt stearate were not detected at the detection limits of 0.6, 0.006 and 0.0005 mg/kg food simulant, respectively. Butadiene was not detected in the PET bottles at a detection limit of 0.33 mg/kg plastic. For PET formulated with the maximum 1% of the active copoymer, the migration of the low molecular weight fraction (LMWF of the copolymer was estimated to be less than 35 µg/kg food. The CEF Panel concluded that the use of the copolymer up to 1% w/w in PET for contact with all types of foods at temperature up to 95°C and the use of cobalt stearate as oxidation catalyst in PET, is not of safety concern for the consumer.

EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (CEF

2012-10-01

388

Communic Acids: Occurrence, Properties and Use as Chirons for the Synthesis of Bioactive Compounds  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Communic acids are diterpenes with labdane skeletons found in many plant species, mainly conifers, predominating in the genus Juniperus (fam. Cupresaceae). In this review we briefly describe their distribution and different biological activities (anti- bacterial, antitumoral, hypolipidemic, relaxing smooth muscle, etc.). This paper also includes a detailed explanation of their use as chiral building blocks for the synthesis of bioactive natural products. Among other uses, communic acids have ...

Arteaga, Alejandro F.; Pilar Arteaga; Arteaga, Jesu?s F.; Barrero, Alejandro F.; Mar Herrador, M.

2012-01-01

389

Synthesis of the A,B,C-ring system of hexacyclinic acid.  

Science.gov (United States)

[structure: see text] The synthesis of the A,B,C-ring system (2) of hexacyclinic acid (1) is achieved starting from a selective Diels-Alder reaction followed by vinyl cuprate addition. The diastereoselective reduction of the ketone carbonyl at C16 could be achieved with LiAlH(4). An intramolecular Michael addition established the ring system stereoselectively, providing access to the selective generation of 9 out of the 14 stereocenters of hexacyclinic acid. PMID:15496056

Stellfeld, Timo; Bhatt, Ulhas; Kalesse, Markus

2004-10-28

390

Enantioselective total synthesis of isishippuric acid B via intramolecular Michael reaction.  

Science.gov (United States)

The first enantioselective total synthesis of isishippuric acid B bearing a novel 4,5-seco-6-norquadrane skeleton was accomplished from (R)-citronellal with use of a Diels-Alder cycloaddition and an intramolecular Michael addition as the ring-forming steps. Comparison of the optical rotation of the synthetic material with that of the natural product confirmed the absolute configuration of isishippuric acid B to be 1R, 2R, 8R, and 11R. PMID:17539655

Torihata, Munefumi; Nakahata, Takashi; Kuwahara, Shigefumi

2007-06-21

391

Synthesis and biological evaluation of ambradiolic acid as an inhibitor of glycogen phosphorylase.  

Science.gov (United States)

Ambradiolic acid (3) with oleanane skeleton is a natural pentacyclictriterpene. The first synthesis of 3 starting from 23-hydroxybetulinic acid (2) has been accomplished in 12-steps with a total yield of 18.1% in our study. Compound 3 was further biologically evaluated and found to exhibit significant inhibitory activity against rabbit muscle glycogen phosphorylase (GP) with an IC50 value of 12.4?M, suggesting it could be a potential lead compound for the development of hypoglycemic drugs. PMID:25447165

Liu, Jie; Zhang, Hengyuan; Zhu, Peiqing; Wu, Xiaoming; Yao, Hequan; Ye, Wencai; Jiang, Jieyun; Xu, Jinyi

2015-01-01

392

Synthesis and HIV-1 integrase inhibitory activities of caffeic acid dimers derived from Salvia officinalis.  

Science.gov (United States)

The synthesis of two caffeoyl-coumarin conjugates, derived from sagecoumarin, has been accomplished, starting from ferulic acid, isoferulic acid and sesamol. Both compounds exhibited potent inhibitory activities at micromolar concentrations against HIV-1 integrase in 3'-end processing reaction but were less effective against HIV-1 replication in a single-round infection assay of HeLa-beta-gal-CD4+ cells. PMID:16183277

Bailly, Fabrice; Queffelec, Clémence; Mbemba, Gladys; Mouscadet, Jean-François; Cotelle, Philippe

2005-11-15

393

Synthesis of 2-[11C]cyano-isonicotinic acid hydrazide  

International Nuclear Information System (INIS)

Isonicotinic acid hydrazide (isoniazid), a drug used in treating tuberculosis has been labelled with carbon-11 at the 2-position. The labelling synthesis starts with methyl isonicotinate treated with dimethyl sulfate. The resulting salt solution is loaded onto silica gel and dried, followed by treatment with carbon-11 labelled hydrocyanic acid. Work-up gave the labelled compound with an average 32% radiochemical yield. Subsequent treatment with hydrazine hydrate yielded isoniazid

394

Amino-acid-assisted synthesis and size-dependent magnetic behaviors of hematite nanocubes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This article reports the amino-acid-assisted synthesis and size-dependent magnetic properties of hematite nanocubes. The products were characterized using x-ray diffraction, Raman spectroscopy, transmission electron microscopy (TEM), and high-resolution TEM. The magnetic behavior of hematite nanocubes was studied using a vibrating sample magnetometer at room temperature. The sizes of hematite nanocubes were controlled by tuning the reaction parameters. The amino acid has double-hydrophilic fu...

Cao, H.; Wang, G.; Warner, Jh; Watt, Aar

2008-01-01

395

The synthesis of hydroxy-iso-evoninic acid via a benzilic ester rearrangement  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Hydroxy-iso-evoninic acid is a pyridine diacid alkaloid present in nine natural products belonging to the Celastraceae plant family. The relative and absolute stereochemistry of the two stereocentres in this compound, which invariably occurs as a macrocyclic esterifying ligand between the C-3 and C-13 alcohols of ?-dihydroagarofuran sesquiterpenes, were not assigned during isolation and no synthesis has yet been reported. The natural products containing hydroxy-iso-evoninic acid are of medic...

Warren, Sarah Ann

2012-01-01

396

Cesium salts of phosphotungstic acid: Comparison of surface acidity, leaching stability and catalytic activity for the synthesis of ?-ketoenol ethers  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english Catalytic activity of Cs xH3-xPW12O40 catalysts were investigated in the synthesis of ?-ketoenol ethers. It was found that activity; acidity, solubility and consequently, recoverability of these catalysts are related to cesium content. A series of ?-ketoenol ether derivatives were synthesized by usi [...] ng Cs25H0.5PW12O40 catalyst in high to excellent yields. This catalyst showed highest surface acidity and lowest solubility in reaction media in comparison with the other cesium content salts.

Ezzat, Rafiee; Masoud, Kahrizi.

2013-08-01

397

Synthesis of homo and hetero metal-phosphonate frameworks from bi-functional aminomethylphosphonic acid  

International Nuclear Information System (INIS)

The reaction between aminomethylphosphonic acid (ampa) and the metal salts of Zn, Cd, Hg, Pb, Ag, and Cu afforded seven metal-phosphonate polymers with unique structural features and includes the synthesis of a bimetallic metal-organic framework (Cu/Ag). The characterization of these metal phosphonates is reported by means of infrared spectroscopy, 1H-NMR, 31P-NMR, X-ray crystallography, energy dispersive X-ray (EDX), and thermogravimetric analysis (TGA). Individual structural features are compared based on the preferred coordination mode of ampa and the geometrical requirements for each metallic center that manipulates the structural motif. - Graphical abstract: The synthesis and characterization of polymeric metal phosphonates featuring zinc, cadmium, mercury, lead, and silver phosphonate are described from the reactions of the bi-funtional aminomethylphosphonic acid with the metal precursor in aqueous conditions. These previously undescribed polymers display unusual structural features and include the synthesis of a bimetallic metal-organic framework (Cu/Ag)

398

Easy synthesis of graphene sheets from alfalfa plants by treatment of nitric acid  

Energy Technology Data Exchange (ETDEWEB)

Highlights: ? An easy method for synthesis of graphene sheets using alfalfa plants was introduced. ? An novelty formation mechanism of graphene sheets using alfalfa plants was proposed. ? This method exploits a new carbon source and provides a novel idea to synthesize graphene sheets. -- Abstract: This letter focuses on synthesis of graphene sheets from alfalfa plants by treatment of nitric acid. The transmission electron microscopy image (TEM) demonstrates that the graphene sheets are agglomerated and overlapped, the energy dispersive spectrum (EDS) indicates that the products are pure, and the Raman spectrum shows the graphene sheets are well graphitized. In addition, the formation mechanism of the graphene sheets from alfalfa plants by treatment nitric acid is discussed. These findings inspire the search for a new strategy for synthesis of graphene sheets from renewable natural products, and the lower cost of this new process and carbon source may facilitate industrial production.

Qu, Jiao, E-mail: qujiao@bhu.edu.cn [School of Chemistry and Chemical Engineering, Bohai University, Jinzhou 121013 (China); School of Urban and Environmental Sciences, Northeast Normal University, Changchun 130024 (China); Luo, Chunqiu, E-mail: fplj_lcq@163.com [School of Chemistry and Chemical Engineering, Bohai University, Jinzhou 121013 (China); Zhang, Qian; Cong, Qiao [School of Chemistry and Chemical Engineering, Bohai University, Jinzhou 121013 (China); Yuan, Xing [School of Urban and Environmental Sciences, Northeast Normal University, Changchun 130024 (China)

2013-04-01

399

Easy synthesis of graphene sheets from alfalfa plants by treatment of nitric acid  

International Nuclear Information System (INIS)

Highlights: ? An easy method for synthesis of graphene sheets using alfalfa plants was introduced. ? An novelty formation mechanism of graphene sheets using alfalfa plants was proposed. ? This method exploits a new carbon source and provides a novel idea to synthesize graphene sheets. -- Abstract: This letter focuses on synthesis of graphene sheets from alfalfa plants by treatment of nitric acid. The transmission electron microscopy image (TEM) demonstrates that the graphene sheets are agglomerated and overlapped, the energy dispersive spectrum (EDS) indicates that the products are pure, and the Raman spectrum shows the graphene sheets are well graphitized. In addition, the formation mechanism of the graphene sheets from alfalfa plants by treatment nitric acid is discussed. These findings inspire the search for a new strategy for synthesis of graphene sheets from renewable natural products, and the lower cost of this new process and carbon source may facilitate industrial production

400

Synthesis and Characterization of Molecularly Imprinted Polymers for Phenoxyacetic Acids  

Directory of Open Access Journals (Sweden)

Full Text Available 2-methylphenoxyacetic acid (2-MPA, 2-methyl-4-chlorophenxyacetic acid (MCPA and 4-chlorophenoxyacetic acid (4-CPA were imprinted to investigate the cross-selectivities of molecularly imprinted polymers (MIPs. The result indicates that 2-MPA, which is similar in shape, size and functionality with phenoxyacetic herbicides, are suitable to be used as a suitable template to prepare the MIPs for retaining phenoxyacetic herbicides. To study the ion-pair interactions between template molecules and functional monomer 4-vinylpiridine (4-VP, computational molecular modeling was employed. The data indicate that the cross-selectivities of MIPs for phenoxyacetic acid herbicides depend on the binding energies of complexes.

Canping Pan

2008-01-01

 
 
 
 
401

Bifunctional Role of Thiosalicylic Acid in the Synthesis of Silver Nanoparticles  

Directory of Open Access Journals (Sweden)

Full Text Available Conventional synthesis of silver nanoparticles employs a reducing agent and a capping agent. Surfactants are effec-tive capping agents as they prevent the aggregation of nanoparticles during storage and use. However, the biocompatibility of several of the surfactants is questionable. In this report, the use of thiosalicylic acid as both reducing and capping agent is reported. Compared to conventional synthesis, this methodology requires higher temperature for synthesis, which then is expected to result in aggregates of larger size. The ability of three different synthesis methodologies – direct heating, photochemical and microwave dielectric treatment were evaluated and assessed on the basis of the size, size distribution and stability of the particles. Microwave irradiation was found to be most suitable for achieving particles with a hydrodynamic diameter of 10 nm. Our studies indicate that -COO- group is involved in the reduction of Ag+ and –SH group of TSA is involved in the capping of the nanoparticles.

Ramasamy Indumathy

2010-12-01

402

A novel PEG-based solid support enables the synthesis of > 50 amino acids peptide thioesters and the total synthesis of a functional SUMO-1 peptide conjugate  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A bis(2-sulfanylethyl)amino PEG-based resin enabled the synthesis of large (~50 Aa) SEA or thioester peptides using Fmoc-SPPS. These peptide segments permitted the first total synthesis of a 97 amino acids long SUMO-1-SEA peptide thioester surrogate and of a functional and reversible SUMO-1 peptide conjugate.

Boll, Emmanuelle; Drobecq, Herve?; Ollivier, Nathalie; Raibaut, Laurent; Desmet, Re?mi; Vicogne, Je?rome; Melnyk, Oleg

2014-01-01

403

Role of ribonucleic acid synthesis in conjugational transfer of chromosomal and plasmid deoxyribonucleic acids.  

Science.gov (United States)

A strain of Escherichia coli K-12 containing mutations that allow for the experimental control of RNA and DNA syntheses was constructed to investigate the role that RNA synthesis plays in conjugational DNA transfer when DNA replication is inhibited. The mutations possessed by this strain and its donor derivatives include: (i) thyA, which blocks synthesis of dTMP, causing a requirement for thymine; (ii) deoC, which blocks breakdown of deoxyribose 5-phosphate, permitting growth with low levels of thymine; (iii) pyrF, which blocks synthesis of UMP from OMP, imposing a requirement for uridine; (iv) cdd and pyrG, which block the deamination of cytidine to uridine and the synthesis of CTP from UTP, respectively, causing a requirement for cytidine; (v) codA and codB, which block the deamination of cytosine to uracil and cytosine transport, respectively, preventing the substitution of cytosine for cytidine; and (vi) dnaB, which blocks vegetative but not conjugational DNA replication at 42 degrees C. DNA synthesis can be blocked in the donor strains by the addition of excess uridine when exogenous thymine is not present. We found that RNA synthesis can also be blocked by addition of excess uridine when exogenous cytidine is not present. Blocking RNA synthesis prior to mating, under conditions in which DNA synthesis either is or is not inhibited, depresses DNA transfer. However, under conditions in which DNA synthesis is inhibited, the blocking of RNA synthesis immediately after mating has commenced had no effect on continued conjugational transfer of DNA. Thus, RNA synthesis is needed to initiate but not to continue conjugational DNA transfer. PMID:6163764

Maturin, L J; Curtiss, R

1981-05-01

404

N-azamonobactams. 2. Synthesis of some N-iminoacetic acid and N-glycyl analogues.  

Science.gov (United States)

The synthesis of the title compounds has been accomplished. The N-iminoacetic acid analogues (12a and 12b) containing the aminothiazole type side chain exhibited good in vitro antibacterial activity against Gram-negative organisms. The corresponding N-glycyl derivative (17) was not active. PMID:2754701

Curran, W V; Lenhard, R H

1989-08-01

405

Synthesis of D,L-[2-15N,5-13C]glutamic acid  

International Nuclear Information System (INIS)

A one-pot procedure is described for the synthesis of D,L-[15N,13C]glutamic acid from 2-bromo-4-butyrolactone utilizing potassium 15N-phthalimide and potassium 13C-cyanide as label sources. Following a two column purification procedure, the final product is obtained in 38% yield based on the equimolar label sources. (author)

406

Formic acid electro-synthesis from carbon dioxide in a room temperature ionic liquid.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The novel synthesis of formic acid has been achieved in a room temperature ionic liquid via the reaction of electro-activated carbon dioxide and protons on pre-anodised platinum. Only mild reaction conditions of room temperature and 1 atm CO(2) were used. This work highlights the effect of pre-anodisation on Pt surfaces.

Martindale, Bc; Compton, Rg

2012-01-01

407

Phosphotungstic Acid: An Efficient, Cost-effective and Recyclable Catalyst for the Synthesis of Polysubstituted Quinolines  

Directory of Open Access Journals (Sweden)

Full Text Available Phosphotungstic acid (H3PW12O40 was used as an efficient and recyclable catalyst for the synthesis of polysubstituted quinolines through the Friedländer condensation of 2-aminoarylketone with carbonyl compounds, which was achieved by conventional heating under solvent-free conditions.

Sahareh Bashiribod

2009-03-01

408

Synthesis, Characterization, and Saccharide Binding Studies of Bile Acid − Porphyrin Conjugates  

Directory of Open Access Journals (Sweden)

Full Text Available Synthesis and characterization of bile acid-porphyrin conjugates (BAPs are reported. Binding of saccharides with BAPs in aqueous methanol was studied by monitoring changes in the visible absorption spectral of the porphyrin-moieties. Although these studies clearly showed absorbance changes, suggesting quite high if non-selective binding, the mass spectral studies do not unambiguously support these results.

Vladimír Král

2007-01-01

409

Synthesis and biological evaluation of caffeic acid 3,4-dihydroxyphenethyl ester.  

Science.gov (United States)

A high-yield synthesis of caffeic acid 3,4-dihydroxyphenethyl ester (1) has been achieved through Knoevenagel condensation of 3,4-dihydroxybenzaldehyde and 3,4-dihydroxyphenethyl monomalonate as the key step. Compound 1 was tested against a 56-cell-line cytotoxicity panel and for its free-radical-scavenging activity in the DPPH test. PMID:20092326

Zhang, Zhizhen; Xiao, Binghua; Chen, Qi; Lian, Xiao-Yuan

2010-02-26

410

Synthesis and bioactivity of novel caffeic acid esters from Zuccagnia punctata.  

Science.gov (United States)

Synthesis of novel caffeic acid esters (1 and 2) was accomplished starting from appropriately substituted benzaldehydes (3 and 9). While compound 2 exhibited potent anti-oxidative activity in both the nitroblue tetrazolium and 1,1-diphenyl-2-picrylhydrazyl radical-scavenging models, compound 1 showed moderate 5-lipoxygenase inhibitory activity. PMID:17145655

Ramachandra, M S; Subbaraju, G V

2006-12-01

411

Silica sulfuric acid catalyzed one-pot synthesis of Biginelli reaction in water  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Silica Sulphuric Acid-catalyzed, simple, one-pot, cost effective and environmentally benign process for the synthesis of dihydropyrimidones is described. The novel compuounds were tested for antibacterial activity and was found to be effective against some gram positive and gram negative bacteria..

Mazahar Farooqui*,2

2013-01-01

412

Asymmetric Total Synthesis of (-)-Leuconoxine via Chiral Phosphoric Acid Catalyzed Desymmetrization of a Prochiral Diester.  

Science.gov (United States)

The asymmetric total synthesis of (-)-leuconoxine has been achieved. The desymmetrization of a prochiral diester using a chiral phosphoric acid catalyst produced a highly enantioenriched lactam with excellent yield. The ring construction featuring an intramolecular N-acyliminium cyclization and the one-step pyrrolidone formation using Bestmann's ylide was successfully accomplished. PMID:25522825

Higuchi, Kazuhiro; Suzuki, Shin; Ueda, Reeko; Oshima, Norifumi; Kobayashi, Emiko; Tayu, Masanori; Kawasaki, Tomomi

2015-01-01

413

Recent Progress on the Stereoselective Synthesis of Cyclic Quaternary ?-Amino Acids  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The most recent papers describing the stereoselective synthesis of cyclic quaternary ?-amino acids are collected in this review. The diverse synthetic approaches are classified according to the size of the ring and taking into account the bond that is formed to complete the quaternary skeleton.

Cativiela, Carlos; Ordo?n?ez, Mario

2009-01-01

414

Templated synthesis of nylon nucleic acids and characterization by nuclease digestion.  

Science.gov (United States)

Nylon nucleic acids containing oligouridine nucleotides with pendent polyamide linkers and flanked by unmodified heteronucleotide sequences were prepared by DNA templated synthesis. Templation was more efficient than the single-stranded synthesis: Coupling step yields were as high as 99.2%, with up to 7 amide linkages formed in the synthesis of a molecule containing 8 modified nucleotides. Controlled digestion by calf spleen phosphodiesterase enabled the mapping of modified nucleotides in the sequences. A combination of complete degradation of nylon nucleic acids by snake venom phosphodiesterase and dephosphorylation of the resulting nucleotide fragments by bacterial alkaline phosphatase, followed by LCMS analysis, clarified the linear structure of the oligo-amide linkages. The templated synthesis strategy afforded nylon nucleic acids in the target structure and was compatible with the presence heteronucleotides. The complete digestion procedure produced a new species of DNA analogues, nylon ribonucleosides, which display nucleosides attached via a 2'-alkylthio linkage to each diamine and dicarboxylate repeat unit of the original nylon nucleic acids. The binding affinity of a nylon ribonucleoside octamer to the complementary DNA was evaluated by thermal denaturing experiments. The octamer was found to form stable duplexes with an inverse dependence on salt concentration, in contrast to the salt-dependent DNA control. PMID:23125913

Liu, Yu; Wang, Risheng; Ding, Liang; Sha, Roujie; Seeman, Nadrian C; Canary, James W

2012-01-01

415

Oxidative allylic rearrangement of cycloalkenols: Formal total synthesis of enantiomerically pure trisporic acid B  

Directory of Open Access Journals (Sweden)

Full Text Available Enantiomerically highly enriched unsaturated ?-ketoesters bearing a quaternary stereocenter can be utilized as building blocks for the synthesis of natural occurring terpenes, i. a., trisporic acid and its derivatives. An advanced building block has been synthesized in a short reaction sequence, which involves an oxidative allylic rearrangement initiated by pyridinium dichromate (PDC as the key step.

Bernhard Westermann

2011-04-01

416

Synthesis of 2-(alkylamino-1-phenylethane-1-thiosulfuric acids, potential schistosomicides  

Directory of Open Access Journals (Sweden)

Full Text Available The total synthesis of seven here-to-fore unreported aromatic aminoalkanethiosulfuric acids, their physical properties and those of the aminoalcohol and bromoalkanamine intermediates are reported. All structures were established by including ¹H and 13C NMR, IR and MS spectroscopy and elemental analysis.

Liliani Salum Alves Moreira

2000-08-01

417

A stereoselective synthesis of (R)-(-)-rolipram from L-glutamic acid  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A stereoselective synthesis of (R)-(-)-rolipram from L-glutamic acid is described. The key step is a stereoselective Michael addition of an arylcuprate to a modified pyroglutamic derivative which acts as the template to induce the stereoselectivity. Facile manipulation of the enantiomerically pure Michael product afforded the expected therapeutic agent.

Di?az Marti?nez, Adolfo; Siro Herrero, Jorge G.; Garci?a Navi?o, Jose? Luis; Vaquero Lo?pez, Juan Jose?; A?lvarez-builla Go?mez, Julio

1997-01-01

418

Tannic acid Catalyzed an Efficient Synthesis of 2,4,5-Triaryl-1H-Imidazole  

Directory of Open Access Journals (Sweden)

Full Text Available Tannic acid (C76H52O46 has been found to be an efficient catalyst for one-pot synthesis of 2,4,5-triaryl substituted imidazoles by the reaction of an arylaldehyde, benzyl/benzoin and an ammonium acetate. The short reaction time and excellent yields making this protocol practical and economically attractive.

Shitole Nana Vikram

2013-05-01

419

Synthesis and biological evaluation of new salicylate macrolactones from anacardic acids  

International Nuclear Information System (INIS)

In connection with our ongoing investigation in the search for new bioactive compounds using non-isoprenoid phenolic lipids from Anacardium occidentale as starting material, we describe the synthesis and cytotoxicity screening of some novel salicylate macrolactones prepared from anacardic acids, the major constituents of natural cashew nut-shell liquid (CNSL). (author)

420

Synthesis of deuterated [D32 ]oleic acid and its phospholipid derivative [D64 ]dioleoyl-sn-glycero-3-phosphocholine.  

Science.gov (United States)

Oleic acid and its phospholipid derivatives are fundamental to the structure and function of cellular membranes. As a result, there has been increasing interest in the availability of their deuterated forms for many nuclear magnetic resonance, infrared, mass spectroscopy and neutron scattering studies. Here, we present for the first time a straightforward, large-scale (gram quantities) synthesis of highly deuterated [D32 ]oleic acid by using multiple, yet simple and high yielding reactions. The precursors for the synthesis of [D32 ]oleic acid are [D14 ]azelaic acid and [D17 ]nonanoic acid, which were obtained by complete deuteration (>98% D) of their (1) H forms by using metal catalysed hydrothermal H/D exchange reactions. The oleic acid was produced with ca. 94% D isotopic purity and with no contamination by the trans-isomer (elaidic acid). The subsequent synthesis of [D64 ]dioleoyl-sn-glycero-3-phosphocholine from [D32 ]oleic acid is also described. PMID:24285531

Darwish, Tamim A; Luks, Emily; Moraes, Greta; Yepuri, Nageshwar R; Holden, Peter J; James, Michael

2013-01-01

 
 
 
 
421

Effect of Whole-Body X-Irradiation of the Synthesis of Individual Fatty Acids in Liver Slices from Normal and Fasted Rats  

DEFF Research Database (Denmark)

(1) Using (2-14C) acetate and (1-14C) butyrate as precursors, rat-liver fatty acids were synthesized in vitro and assayed by paper chromatography. (2) Whole-body x-irradiation induced a change in the synthetic pattern of hepatic fatty acids towards a relatively enhanced synthesis of palmitic acid. (3) X-irradiation and fasting seem to have opposite effects on fatty-acid synthesis. X-irradiation counteracts the drop in total synthesis and the relatively enhanced synthesis of palmitoleic acid induced by fasting. The relative enhancement of palmitic-acid synthesis mentioned under (2) stands in contrast to the effect of fasting, which specifically decreases the hepatic synthesis of palmitic acid. (4) There is a general similarity between corresponding fatty-acid patterns based on synthesis from (2-14C) acetate and (1-14C) butyrate, respectively.

Hansen, Heinz Johs. Max; Hansen, Lisbeth Grænge

1965-01-01

422

EFFECT OF LEAD ON GAMMA AMINO BUTYRIC ACID SYNTHESIS  

Science.gov (United States)

The project studies the inhibitory effect of lead on the enzymatic activity of brain glutamic amino acid decarboxylase (GADC). The enzyme is responsible for the catalytic formation of gamma amino butyric acid (GABA) inhibitory neurons which is believed to be involved with the tra...

423

Synthesis and evaluation of caffeic acid amides as antioxidants.  

Science.gov (United States)

A series of amides of caffeic acid has been synthesised and their antioxidant properties evaluated as lipid peroxidation inhibitors. Anilides of caffeic acid were found to be very efficient antioxidants with IC50's of 0.3 microM. PMID:11206462

Rajan, P; Vedernikova, I; Cos, P; Berghe, D V; Augustyns, K; Haemers, A

2001-01-22

424

Synthesis and biological evaluation of abietic acid derivatives.  

Science.gov (United States)

A series of C18-oxygenated derivatives of abietic acid were synthesized and evaluated for their cytotoxic, antimycotic, and antiviral activities. In general, the introduction of an aldehyde group at C18 did improve the resultant bioactivity, while the presence of an acid or alcohol led to less active compounds. PMID:19217699

González, Miguel A; Correa-Royero, Julieth; Agudelo, Lee; Mesa, Ana; Betancur-Galvis, Liliana

2009-06-01

425

EFFECTS OF ETHYLENE CHLOROHYDRIN ON FATTY ACID SYNTHESIS  

Science.gov (United States)

Male chicks weighing 700 to 900 g. received an acute or eight doses IG of 60 or 40 mg/kg ethylene chlorohydrin (ECH) respectively and were sacrificed eighteen hours after the last dose. Mitochondrial elongation of fatty acids was decreased significantly while fatty acid synthetas...

426

Inhibition of FASN reduces the synthesis of medium-chain fatty acids in goat mammary gland.  

Science.gov (United States)

Fatty acid synthase (FASN) is known as a crucial enzyme of cellular de novo fatty acid synthesis in mammary gland which has been proved as the main source of short and medium-chain fatty acids of milk. However, the regulatory role of FASN in goat-specific milk fatty acids composition remains unclear. We cloned and analyzed the full-length of FASN gene from the mammary gland of Capra hircus (Xinong Saanen dairy goat) (DQ 915966). Comparative gene expression analysis suggested that FASN is predominantly expressed in fat, small intestine and mammary gland tissues, and expresses higher level at lactation period. Inhibition of FASN activity by different concentrations (0, 5, 15, 25 and 35 ?M) of orlistat, a natural inhibitor of FASN, resulted in decreased expression of acetyl-CoA carboxylase ? (ACC?), lipoprotein lipase and heart-type fatty acid binding protein (H-FABP) in a concentration-dependent manner in goat mammary gland epithelial cells (GMEC). Similar results were also obtained by silencing of FASN. Additionally, reduction of FASN expression also led to apparent decline of the relative content of decanoic acid (C10:0) and lauric acid (C12:0) in GMEC. Our study provides a direct evidence for inhibition of FASN reduces cellular medium-chain fatty acids synthesis in GMEC. PMID:24909980

Zhu, J J; Luo, J; Wang, W; Yu, K; Wang, H B; Shi, H B; Sun, Y T; Lin, X Z; Li, J

2014-09-01

427

The synthesis of barbituric acid and some of its derivatives isotopically labelled with 15N  

International Nuclear Information System (INIS)

Full text: Barbituric acid is the parent compound of a large class of barbiturates that have central nervous system depressant properties, although barbituric acid itself is not pharmacologically active. In recent years, barbituric acid derivatives have been studied as antitumor, anticancer and anti-osteoporosis agents. The aim of this paper is to present the synthesis of barbituric acid-15N, 5,5-diethylbarbituric acid-15N (Veronal-15N) and 5-ethyl-5-phenylbarbituric acid- 15N (Phenobarbitone-15N) . As isotopically labelled material we used urea-15N2, 99 at.% 15N produced at National Institute for Research and Development of Isotopic and Molecular Technologies, Cluj-Napoca, Romania. All compounds were fully characterized by Mass Spectrometry analyses, by FT-IR Spectroscopy and RX Diffraction, and the isotopic label was determined by MS on the molecular compounds. (author)

428

New synthesis of (11C)labeled fatty acid from H11CN  

International Nuclear Information System (INIS)

(11C)labeled palmitic acid has been used for the quantitative measurement of both regional myocardial perfusion and regional fatty acid metabolism with a PET imaging system. 3-Methyl-(1-11C)heptadecanoic acid, a fatty acid analog designed to inhibit the ?-oxidation process by preventing the formation of corresponding ?-ketoacyl SCoA has also been a useful myocardial metabolic tracer for PET. These (11C)labeled fatty acids have been synthesized by the use of the Grignard reaction. However this method has disadvantages such as the need for absolutely anhydrous solvent and the requirement for a lot of starting material (alkyl bromide). Therefore we proposed a new synthesis of (11C)labeled fatty acid by the use of H11CN which resulted in a better radiochemical yield and reproducibility. (author)

429

[Arachidonoyl amino acids and arachidonoyl peptides: synthesis and properties].  

Science.gov (United States)

N-Arachidonoyl (AA) derivatives of amino acids (glycine, phenylalanine, proline, valine, gamma-amino butyric acid (GABA), dihydroxyphenylalanine, tyrosine, tryptophan, and alanine) and peptides (Semax, MEHFPGP, and PGP) were synthesized in order to study the biological properties of acylamino acids. The mass spectra of all the compounds at atmospheric pressure electrospray ionization display the most intense peaks of protonated molecular ions; the detection limits for these compounds are 10 fmol per sample. AA-Gly showed the highest inhibitory activity toward fatty acid amide hydrolase from rat brain (IC50 6.5 microM) among all the acylamino acids studied. AA-Phe, AA-Tyr, and AA-GABA exhibited a weak but detectable inhibitory effect (IC50 55, 60, and 50 microM, respectively). The acylated amino acids themselves, except for AA-Gly, were stable to the hydrolysis by this enzyme. All the arachidonoylamino acids inhibited cabbage phospholipase D to various degrees; AA-GABA and AA-Phe proved to be the most active (IC50 20 and 27 microM, respectively). Attempts to detect the biosynthesis of AA-Tyr in homogenates of rat liver and nerve tissue showed no formation in vitro of either this acylamino acid or AA-dopamine and AA-Phe, the products of its metabolism. The highest contents of these metabolites were detected in liver homogenate and in the brain homogenate, respectively. Acylamino acids exert no cytotoxic effect toward the glioma C6 cells. It was shown that N-acylation of Semax with arachidonic acid results in enhancement of its hydrolytic stability and increases its affinity for the sites of specific binding in rat cerebellum membranes. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2006, vol. 32, no. 3; see also http://www.maik.ru. PMID:16808168

Bezuglov, V V; Gretskaia, N M; Blazhenova, A V; Adrianova, E L; Akimov, A V; Bobrov, M Iu; Nazimov, I V; Kisel', M I; Sharko, O L; Novikov, A V; Krasnov, N V; Shevchenko, V P; V'iunova, T V; Miasoedova, N F

2006-01-01

430

Synthesis of N,N-Bis(nonaflyl) Squaric Acid Diamide and its Application to Organic Reactions  

Energy Technology Data Exchange (ETDEWEB)

We have developed a new strong Br?nsted acid bearing two nonaflyl groups based on the squaric acid scaffold. The Br?nsted acid 2 showed the almost same reactivity as bistriflyl squaramide 1 in Mukaiyama aldol and Michael reactions of benzaldehyde with silyl enol ether. Moreover, the utility of Br?nsted acid 2 could be expanded to carbonyl ene reaction of rac-citronellal. Further application of this new Br?nsted acid to organic reactions and to flow system reactors is currently underway in our laboratory. Br?nsted acid catalysis is one of the growing fields in modern organic synthesis.1 Although several Br?nsted acids, such as urea/thiourea, TADDOL, and phosphoric acid, have been applied to a variety of organic reactions, other Br?nsted acid scaffolds have been much less explored. Recently, Rawal et al have developed a Br?nsted acid catalyst based on squaric acid moiety and successfully applied it as a catalyst for conjugate addition of 1,3-dicarbonyl compounds to nitroolefins. More recently, we have developed a strong Br?nsted acid derived from squaric acid by introducing a strong electron withdrawing trifluoromethanesulfonyl (Tf) group and applied it to Mukaiyama aldol and Michael reaction of a variety of aldehydes, ketones, and ?,?-unsaturated ketones. As a continuing effort to develop strong Br?nsted acids based on the squaric acid scaffold, it was expected that replacement of Tf group with a longer perfluoro-alkanesulfonyl group would be able to tune the physical properties, such as solubilities in organic solvents and fluoro-philicity, without loss of reactivity. Herein, we report the development of a new Br?nsted acid based on the squaric acid scaffold carrying two nonafluorobutanesulfonyl (Nf) groups and the preliminary results of its reactivity to various organic reactions.

Cheon, Cheol Hong; Yamamoto, Hisashi [The Univ. of Chicago, Chicago (United States)

2010-03-15

431

Synthesis of N,N-Bis(nonaflyl) Squaric Acid Diamide and its Application to Organic Reactions  

International Nuclear Information System (INIS)

We have developed a new strong Br?nsted acid bearing two nonaflyl groups based on the squaric acid scaffold. The Br?nsted acid 2 showed the almost same reactivity as bistriflyl squaramide 1 in Mukaiyama aldol and Michael reactions of benzaldehyde with silyl enol ether. Moreover, the utility of Br?nsted acid 2 could be expanded to carbonyl ene reaction of rac-citronellal. Further application of this new Br?nsted acid to organic reactions and to flow system reactors is currently underway in our laboratory. Br?nsted acid catalysis is one of the growing fields in modern organic synthesis.1 Although several Br?nsted acids, such as urea/thiourea, TADDOL, and phosphoric acid, have been applied to a variety of organic reactions, other Br?nsted acid scaffolds have been much less explored. Recently, Rawal et al have developed a Br?nsted acid catalyst based on squaric acid moiety and successfully applied it as a catalyst for conjugate addition of 1,3-dicarbonyl compounds to nitroolefins. More recently, we have developed a strong Br?nsted acid derived from squaric acid by introducing a strong electron withdrawing trifluoromethanesulfonyl (Tf) group and applied it to Mukaiyama aldol and Michael reaction of a variety of aldehydes, ketones, and ?,?-unsaturated ketones. As a continuing effort to develop strong Br?nsted acids based on the squaric acid scaffold, it was expected that replacement of Tf group with a longer perfluoro-alkanesulfonyl group would be able to tune the physical properties, such as solubilities in organic solvents and fluoro-philicity, without loss of reactivity. Herein, we report the development of a new Br?nsted acid based on the squaric acid scaffold carrying two nonafluorobutanesulfonyl (Nf) groups and the preliminary results of its reactivity to various organic reactions

432

Synthesis and characterization of hydrogen-bond acidic functionalized graphene  

Science.gov (United States)

Hexafluoroisopropanol phenyl group functionalized materials have great potential in the application of gas-sensitive materials for nerve agent detection, due to the formation of strong hydrogen-bonding interactions between the group and the analytes. In this paper, take full advantage of ultra-large specific surface area and plenty of carbon-carbon double bonds and hexafluoroisopropanol phenyl functionalized graphene was synthesized through in situ diazonium reaction between -C=C- and p-hexafluoroisopropanol aniline. The identity of the as-synthesis material was confirmed by transmission electron microscopy, Raman spectroscopy, ultraviolet visible spectroscopy, X-ray photoelectron spectroscopy and thermo gravimetric analysis. The synthesis method is simply which retained the excellent physical properties of original graphene. In addition, the novel material can be assigned as an potential candidate for gas sensitive materials towards organophosphorus nerve agent detection.

Yang, Liu; Han, Qiang; Pan, Yong; Cao, Shuya; Ding, Mingyu

2014-05-01

433

Synthesis of amino acid derivatives via vinylalumination and hydroboration  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The addition of a vinylaluminum species across aldehydes or imines to afford the corresponding allylic alcohols or amines is termed as vinylalumination. This reaction allows the inclusion of several functional groups on the vinyl moiety for the convenient synthesis of functionalized allyl alcohols and amines. For example, vinylalumination has been used for the preparation of ?-alkylidene-?-hydroxy esters. Due to its shorter reaction time, compatibility with fluorocarbonyls, and accommodatio...

Bland, Layla D.

2006-01-01

434

Glutathione deficiency increases hepatic ascorbic acid synthesis in adult mice.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Glutathione deficiency, induced in adult mice by administering buthionine sulfoximine (an inhibitor of glutathione synthesis), led to a rapid and substantial increase in ascorbate in the liver. This effect was apparent 2-4 hr after giving the inhibitor; subsequently, the level of ascorbate decreased and that of dehydroascorbate increased markedly, supporting the conclusion that glutathione functions physiologically to keep ascorbate in its reduced form. In kidney and lung also, ascorbate leve...

Ma?rtensson, J.; Meister, A.

1992-01-01

435

Synthesis of 2-(N-Benzylpyrrolyl)-benzimidazoles Using Polyphosphoric Acid Prompted Cyclocondensation  

Science.gov (United States)

Synthesis of a series of 2-substituted benzimidazoles was carried out for screening anti-inflammatory activities. 2-(N-benzylpyrrolyl)-benzimidazoles 9a–k were synthesized from N-benzyl-2-pyrrole carboxylic acids 8a–d and 4-substituted-1,2-phenylenediamines by cyclocondensation utilizing polyphosphoric acid (PPA) as condensing agent. The N-benzyl-2-pyrrole carboxylic acids were prepared by standard method of N-benzylation of 2-pyrrole carboxylate using NaH/DMF and appropriately substituted benzyl halides followed by alkaline hydrolysis. PMID:21423826

Mochona, Bereket; Le, Laine; Gangapuram, Madhavi; Mateeva, Nelly; Ardley, Tiffany; Redda, Kinfe K.

2011-01-01

436

Stereoselective synthesis of 1-aminoalkanephosphonic acids with two chiral centers and their activity towards leucine aminopeptidase.  

Science.gov (United States)

The stereoselective synthesis of 1-amino-2-alkylalkanephosphonic acids, namely, compounds bearing two chiral centers, was achieved by the condensation of hypophosphorous acid salts of (R)(+) or (S)(-)-N-alpha-methylbenzylamine with the appropriate aldehydes in isopropanol. Simultaneous deprotection and oxidation by the action of bromine water provided equimolar mixtures of the RS:RR and SR:SS diastereomers of desired acids. They appeared to act as moderate inhibitors of kidney leucine aminopeptidase with potency dependent on the absolute configuration of both centers of chirality. PMID:12884381

Drag, Marcin; Pawelczak, Malgorzata; Kafarski, Pawel

2003-01-01

437

One pot, rapid and efficient synthesis of water dispersible gold nanoparticles using alpha-amino acids  

Science.gov (United States)

A detailed study on the synthesis of spherical and monodispersed gold nanoparticles (AuNPs) using all of the 20 naturally occurring ?-amino acids has been reported. The synthesized nanoparticles have been further characterized using various techniques such as absorbance spectroscopy, transmission electron microscopy, dynamic light scattering and nuclear magnetic resonance. Size control of the nanoparticles has been achieved by varying the ratio of the gold ion to the amino acid. These monodispersed water soluble AuNPs synthesized using non-toxic, naturally occurring ?-amino acids as reducing and capping/stabilizing agents serve as a remarkable example of green chemistry.

Wangoo, Nishima; Kaur, Sarabjit; Bajaj, Manish; Jain, D. V. S.; Sharma, Rohit K.

2014-10-01

438

Synthesis and characterisation of fatty acid bearing technetium complexes and their precursor stages  

International Nuclear Information System (INIS)

Over the past 25 years numerous research groups have studied the synthesis of 99mTc-coordinated fatty acids as a means of assessing the metabolic state of individual areas of the heart. Diverse chelate groups have been used for binding the radiometal to a fatty acid skeleton. As yet, however, the use of such 99mTc preparations in nuclear medicine has not been possible due to insufficient accumulation rates and poor substrate recognition during ? oxidation. The present study is therefore intended as a contribution to the study of new developments in technetium coordination chemistry and their suitability for the biocompatible marking of fatty acids. The focal areas of the present study were therefore as follows: synthesis and characterisation of ? functionalised fatty acid derivatives, which according to various coordination concepts should be suitable for binding to technetium; synthesis and structural characterisation of the relevant metal complexes using rhenium, an element similar to technetium in terms of its coordination chemistry which allows experimentation without radioactivity; and transfer of the coordination chemistry of the nonradioactive rhenium reference compound to the no-carrier-added 99mTc complex and provision of suitable 99mTc marked fatty acid preparations for a first assessment in the Langendorff perfused heart model

439

Retinoic acid synthesis and functions in early embryonic development  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Retinoic acid (RA is a morphogen derived from retinol (vitamin A that plays important roles in cell growth, differentiation, and organogenesis. The production of RA from retinol requires two consecutive enzymatic reactions catalyzed by different sets of dehydrogenases. The retinol is first oxidized into retinal, which is then oxidized into RA. The RA interacts with retinoic acid receptor (RAR and retinoic acid X receptor (RXR which then regulate the target gene expression. In this review, we have discussed the metabolism of RA and the important components of RA signaling pathway, and highlighted current understanding of the functions of RA during early embryonic development.

Kam Richard Kin Ting

2012-03-01

440

A unified strategy for the synthesis of the C1-C14 fragment of marinolic acids, mupirocins, pseudomonic acids and thiomarinols: total synthesis of pseudomonic acid methyl monate C.  

Science.gov (United States)

A flexible stereoselective approach to the common C1-C14 skeleton present in natural products of the pseudomonic acid family is described. The strategy has been extended and the total synthesis of pseudomonic acid methyl monate C was achieved. The key synthetic reactions utilized include Achmatowicz rearrangement, Johnson-Claisen rearrangement, Julia-Kocienski olefination, and Horner-Wadsworth-Emmons olefination reaction. PMID:24691713

Sridhar, Y; Srihari, P

2014-05-14

 
 
 
 
441

[Synthesis of hydroxamic acids and study of their complexes with iron (II) and (III) ions].  

Science.gov (United States)

Hydroxamic acids are widespread in the tissues of plants, in metabolites of bacteria and fungi, including complex compounds with metal ions. These acids have wide spectrum of biological activity and therefore are perspective reagents for analysis of chemical elements. Fourteen aliphatic and aromatic derivatives of hydroxamic acids have been synthesized from esters of carboxylic acids. Photometric reactions of hydroxamic acids with iron (II) and (III) were investigated. Complex formation of iron (II) and (III) depending on pH was studied with series of synthesized hydroxamic acids: octanohydroxamic, maleic hydroxamic, 2-hydroxybenzoxydroxamic, benzoxydroxamic, phthalmonoxydroxamic and 3-metoxybenzohydroxamic acids. Composition of iron (III) complexes with 2-hydroxybenzohydroxamic, octanoxydroxamic, 3-metoxybenzohydroxamic acids and iron (II) with 2-hydroxybenzohydroxamic acid was studied by methods of mole ratio and isomolar solutions. Sensitivity of reagents was evaluated by values of absorption coefficients (epsilon). Stability of complexes in water and organic solvents was investigated. Interaction between iron (III) and hydroxamic acids (octanoxydroxamic, 2-hydroxybenzohydroxamic, 3-metoxybenzohydroxamic) have been applied for quantitative photometric analysis of iron (III) salts. Color reaction of iron (II) with 2-hydroxybenzohydroxamic acid was applied for quantitative photometric determination of iron (II) salts. 3-Metoxybenzohydroxamic acid was proposed as a new indicator for complexonometric analysis of iron (III). Chelatometric titration of iron (III) using this indicator is not influenced by copper, cobalt, zinc, manganese, so this methods is recommended for iron quantity detection in antianemic drugs, which are composed of latter microelements. Synthesis procedure of 2-benzoylamino-3-arylacrylhydroxamic acids from saturated azlactones was created. Color and precipitate reactions of iron (II) and (III), copper (II), nickel (II) and cobalt (II) ions with four newly synthesized acids (with and without substitutes in aromatic ring) were studied. Sensitivities of reactions between 2-benzoylamino-3-arylacrylhydroxamic acids and iron (II) and (III) were evaluated and compared with 2-hydroxybenzohydroxamic acid. PMID:12474660

Nenortiene, Palma; Sapragoniene, Marija; Stankevicius, Antanas

2002-01-01

442

Synthesis and catalytic application of amino acid based dendritic macromolecules  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The use of amino acid based dendrimers as molecular scaffolds for the attachment of catalytically active organometallic Ni ''pincer'' complexes, via a urea functionality, is described; the dendrimer catalysts have comparable activity to their mononuclear (NCN)NiX analogues.

Koten, G.; Gossage, R. A.; Jastrzebski, J. T. B. H.; Ameijde, J.; Mulders, S. J. E.; Brouwer, Arwin J.; Liskamp, R. M. J.

1999-01-01

443

Synthesis and scavenging role of furan fatty acids  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Fatty acids comprise a large class of compounds that serve broad roles in cells and society. These hydrophobic compounds provide integrity for biological membranes, make them impermeable to solutes and toxins, and modulate the cellular response to signals or stresses. Fatty acids, or the products derived from them, are also important as dietary supplements, lubricants, specialty chemicals, and fuels. Their potential utility in biology or industry could be increased by producing novel classes ...

Lemke, Rachelle A. S.; Peterson, Amelia C.; Ziegelhoffer, Eva C.; Westphall, Michael S.; Tjellstro?m, Henrik; Coon, Joshua J.; Donohue, Timothy J.

2014-01-01

444

An inproved synthesis of 24- 13C-labeled bile acids using formyl esters and a modified lead tetraacetate procedure  

International Nuclear Information System (INIS)

An improved synthesis of 24-13C-labeled bile acids has been achieved using formyl derivatives of bile acids and a modified lead tetraacetate procedure. The formylated bile acids were degraded by lead tetraacetate and lithium chloride to formylated 23-chloronorcholanes in 72 to 83% yield. Formylated 23-chloronorcholanes were converted to nitriles in dimethylformamide, which were then hydrolyzed to obtain C-24 labeled bile acids in yield of 80 to 90% of labeled sodium cyanide used. This method results in a higher yield and a purer product with less manipulation than previously reported procedures for synthesis of labeled bile acids

445

Regulation of bile acid synthesis in humans: studies on cholesterol 7 alpha-hydroxylation in vivo.  

Science.gov (United States)

Over the last few years important progress has been made on the quantitation of cholesterol 7 alpha-hydroxylation, the rate-limiting step of bile acid synthesis. The use of a technique based on the determination of body water tritium enrichment after i.v. administration of [7 alpha-3H] cholesterol has allowed in vivo investigation of this step in humans in different experimental conditions. The cholesterol 7 alpha-hydroxylation rate was not affected by the administration of the hydrophilic bile acid ursodeoxycholic acid (UDCA) whereas it was significantly reduced by the more hydrophobic chenodeoxycholic acid (CDCA) and even more so by the strongly hydrophobic deoxycholic acid (DCA). The administration of cholestyramine induced a significant dose-related increase of 7 alpha-hydroxylation along with a correspondent decrease in plasma cholesterol. The administration of simvastatin exerted no effect on cholesterol 7 alpha-hydroxylation despite a marked decrease in serum cholesterol. Treatment with fibrates reduced plasma lipid levels and 7 alpha-hydroxylation rates. Hydroxylation rates were unchanged in familial hypercholesterolaemia and increased in familial combined hyperlipidaemia. These data suggest that in humans bile acid synthesis can be affected by quantitative and qualitative alterations of the enterohepatic circulation of bile acids. Changes in cholesterol 7 alpha-hydroxylation rates may be associated with alterations in plasma lipid levels, but such a relationship is ill-defined and seems to vary with the different experimental models. PMID:8775473

Bertolotti, M; Abate, N; Loria, P; Concari, M; Guicciardi, M E; Dilengite, M A; Bozzoli, M; Carubbi, F; Carulli, N

1995-01-01

446

Synthesis and Quantitative Structure-Property Relationships of Side Chain-Modified Hyodeoxycholic Acid Derivatives  

Directory of Open Access Journals (Sweden)

Full Text Available Bile acids have emerged as versatile signalling compounds of a complex network of nuclear and membrane receptors regulating various endocrine and paracrine functions. The elucidation of the interconnection between the biological pathways under the bile acid control and manifestations of hepatic and metabolic diseases have extended the scope of this class of steroids for in vivo investigations. In this framework, the design and synthesis of novel biliary derivatives able to modulate a specific receptor requires a deep understanding of both structure-activity and structure-property relationships of bile acids. In this paper, we report the preparation and the critical micellization concentration evaluation of a series of hyodeoxycholic acid derivatives characterized by a diverse side chain length and by the presence of a methyl group at the alpha position with respect to the terminal carboxylic acid moiety. The data collected are instrumental to extend on a quantitative basis, the knowledge of the current structure-property relationships of bile acids and will be fruitful, in combination with models of receptor activity, to design and prioritize the synthesis of novel pharmacokinetically suitable ligands useful in the validation of bile acid-responsive receptors as therapeutic targets.

Antimo Gioiello

2013-08-01

447

Enhanced Synthesis of Alkyl Amino Acids in Miller's 1958 H2S Experiment  

Science.gov (United States)

Stanley Miller's 1958 H2S-containing experiment, which included a simulated prebiotic atmosphere of methane (CH4), ammonia (NH3), carbon dioxide (CO2), and hydrogen sulfide (H2S) produced several alkyl amino acids, including the alpha-, beta-, and gamma-isomers of aminobutyric acid (ABA) in greater relative yields than had previously been reported from his spark discharge experiments. In the presence of H2S, aspariic and glutamic acids could yield alkyl amino acids via the formation of thioimide intermediates. Radical chemistry initiated by passing H2S through a spark discharge could have also enhanced alkyl amino acid synthesis by generating alkyl radicals that can help form the aldehyde and ketone precursors to these amino acids. We propose mechanisms that may have influenced the synthesis of certain amino acids in localized environments rich in H2S and lightning discharges, similar to conditions near volcanic systems on the early Earth, thus contributing to the prebiotic chemical inventory of the primordial Earth.

Parker, Eric T.; Cleaves, H. James; Callahan, Michael P.; Dworkin, James P.; Glavin, Daniel P.; Lazcano, Antonio; Bada, Jeffrey L.

2011-01-01

448

Synthesis, structure, and biological applications of ?-fluorinated ?-amino acids and derivatives.  

Science.gov (United States)

This review gives a broad overview of the state of play with respect to the synthesis, conformational properties, and biological activity of ?-fluorinated ?-amino acids and derivatives. General methods are described for the preparation of monosubstituted ?-fluoro-?-amino acids (Scheme 1). Nucleophilic methods for the introduction of fluorine predominantly involve the reaction of DAST with alcohols derived from ?-amino acids, whereas electrophilic sources of fluorine such as NFSI have been used in conjunction with Arndt-Eistert homologation, conjugate addition or organocatalyzed Mannich reactions. ?,?-Difluoro-?-amino acids have also been prepared using DAST; however, this area of synthesis is largely dominated by the use of difluorinated Reformatsky reagents to introduce the difluoro ester functionality (Scheme 9). ?-Fluoro-?-amino acids and derivatives analyzed by X-ray crystal and NMR solution techniques are found to adopt preferred conformations which are thought to result from stereoelectronic effects associated with F located close to amines, amides, and esters (Figs. 2-6). ?-Fluoro amide and ?-fluoro ethylamide/amine effects can influence the secondary structure of ?-fluoro-?-amino acid-containing derivatives including peptides and peptidomimetics (Figs. 7-9). ?-Fluoro-?-amino acids are also components of a diverse range of bioactive anticancer (e.g., 5-fluorouracil), antifungal, and antiinsomnia agents as well as protease inhibitors where such fluorinated analogs have shown increased potency and spectrum of activity. PMID:23161626

March, Taryn L; Johnston, Martin R; Duggan, Peter J; Gardiner, James

2012-11-01

449