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1

Synthesis of terephthalic acid by isomerization of coal acid  

Energy Technology Data Exchange (ETDEWEB)

Terephthalic acid can be obtained in the presence of a catalyst Cd{sub 3} by isomerixation of potassium salt of coal acid produced from coal oxidation. Effects of the amount of catalyst, initial pressure of CO{sub 2}, reaction temperature and reaction time were investigated. It was confirmed that WSA can be converted to terephthalic acid in the presence of a catalyst. In case of isomerizing the potassium salt of coal acids alone, the optimum conditions of isomerization were as: temperature 430 to 450{sup o}C, initial pressure of CO{sub 2} 4.0 MPa, catalyst CdCO{sub 3} 4% and reaction time 2 h. Such optimum conditions were similar to those of The isomerization by a mixture of potassium coal acids (WSA) which was equivalent to 75% of BPCA and was the effective composition of WSA. It has shown that the selectivity was good. The yield of crude TPA was about 68% if isomerization was carried out with a mixture of potassium salts of coal acid and benzoic acid at its optimum conditions. The yield of TPA was as high as 70% after being deducted from the theoretical yield of BNA dismutation, and about two times of WSA isomerization alone. The purity of the refined TPA was {le} 99%.

Zhang, Q.; Guan, J.; Zhao, S.; Guo, S. [Dalian University of Technology, Dalian (China). Inst. of Coal Chemical Engineering

2003-10-01

2

Mechanochemical synthesis of compounds of terbium and europium with phthalic and terephthalic acids  

International Nuclear Information System (INIS)

Mechanochemical synthesis of Ln2L3·3H2O composition compounds, where Ln = Eu3+, Tb3+, L - phthalic and terephthalic acids is conducted. It is ascertained that the compound yield depends on the molar ratio of reagents, additions, time of mechanical activation. The complex individuality is confirmed by element chemical analysis, IR- and luminescent spectroscopy methods. (author)

1997-09-01

3

Determining organic impurities in mother liquors from oxidative terephthalic acid synthesis by microemulsion electrokinetic chromatography.  

Science.gov (United States)

In this study, a microemulsion electrokinetic chromatography (MEEKC) method was developed to analyze and detect several aromatic acids (benzoic acid (BA), isophthalic acid (IPA), terephthalic acid (TPA), p-toluic acid (p-TA), 4-carboxylbenzaldehyde (4-CBA), trimesic acid (TSA), trimellitic acid (TMA), o-phthalic acid (OPA), and hemimellitic acid (HMA)), which are common organic impurities produced by liquid-phase catalytic oxidation of p-xylene to TPA. The effects of microemulsion composition, column temperature, column length and applied voltage were examined in order to optimize the aromatic acid separations. This work demonstrated that variation in the concentration of surfactant (sodium dodecyl sulfate (SDS)) and oil phase (octane) had a pronounced effect on separation of the nine aromatic acids. It was also found that a decrease in column length had the greatest effect on shortening separation time and improving separation resolution for these aromatic acids when compared to that of an increase in column temperature or applied voltage. However, the nature and concentration of cosurfactants and organic modifiers were found to play only minor roles in the separation mechanism. Thus, a separation with baseline resolution was achieved within 14 min by using a microemulsion solution of pH 2.0 containing 3.7% SDS, 0.975% octane, and 5.0% cyclohexanol; and a 50-cm capillary column (effective length of 40-cm) at 26 degrees C. As a result, the developed MEEKC method successfully determined eight impurities of aromatic acids in the mother liquors produced from the oxidation synthesis of TPA. PMID:19167001

Huang, Hsi-Ya; Wei, Mercury; Lin, Yu-Ru; Lu, Pin-Hsuan

2009-03-20

4

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

5

Effects of synthesis conditions on chemical structures and physical properties of copolyesters from lactic acid, ethylene glycol and dimethyl terephthalate  

Directory of Open Access Journals (Sweden)

Full Text Available Lactic acid/ethylene terephthalate copolyesters were synthesized by the standard melt polycondensation of lactic acid (L, ethylene glycol (EG and dimethyl-terephthalate (DMT. Effects of reaction temperatures and types of catalysts on the structures and properties of the copolymers were examined. In addition, feasibility of promoting the copolymerization process by a novel synthesis step of using thermo-stabilizers was investigated. The results show that a reaction temperature of higher than 180°C is necessary to produce copolymers with appreciable molecular weight. However, degradation was observed when the reaction temperature is higher than 220°C. Triphenyl phosphate (TPP shows promising results as a potential thermo-stabilizer to minimize this problem. It was found that Sb2O3 and Tin(II octoate are most effective among 4 types of catalysts employed in this study. 1H-NMR results indicate that copolymers have a random microstructure composed mainly of single L units alternately linked with ET blocks at various sequential lengths. The longer ET sequence in the chain structure leads to the increase in melting temperature of the copolymer. TGA results show that the resulting copolymers possessed greater thermal stability than commercially-available aliphatic PLA, as a result of the inclusion of T (terephthalate units in the chain structure.

2009-07-01

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Catalytic and Mechanistic Studies of Polyethylene Terephthalate Synthesis  

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Polyethylene terephthalate synthesis by polycondensation of its monomer bis-hydroxy ethylene terephthalate was investigated. Two catalysts were studied; a homogenous one based on antimony and a heterogeneous one based on hydrotalcite. Two methods were applied to monitor the reaction progress; thermogravimetry and calorimetry. The reaction was performed in bulk under non-isothermal conditions in the melt phase. 10 mg of monomer/catalyst mixtures were heated at a constant heating rate in the ra...

Toufaili, Faissal-ali El-

2006-01-01

7

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

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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

8

Poly (ethylene terephthalate synthesis with catalysts derived from chrysotile asbestos  

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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

9

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 ...

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

2013-01-01

10

Sequential pyrolysis of plastic to recover polystyrene HCL and terephthalic acid  

Energy Technology Data Exchange (ETDEWEB)

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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Sequential pyrolysis of plastic to recover polystyrene, HCl and terephthalic acid  

Energy Technology Data Exchange (ETDEWEB)

A process is described for 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. 83 figs.

Evans, R.J.; Chum, H.L.

1995-11-07

12

[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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High rate treatment of terephthalic acid production wastewater in a two-stage anaerobic bioreactor.  

Science.gov (United States)

The feasibility was studied of anaerobic treatment of wastewater generated during purified terephthalic acid (PTA) production in two-stage upflow anaerobic sludge blanket (UASB) reactor system. The artificial influent of the system contained the main organic substrates of PTA-wastewater: acetate, benzoate, and terephthalate. Three parallel operated reactors were used for the second stage, and seeded with a suspended terephthalate degrading culture, with and without additional methanogenic granular sludge (two different types). The first stage UASB-reactor was seeded with methanogenic granular sludge. Reactors were operated at 37 degrees C and pH 7. During the first 300 days of operation a clear distinction between the biomass grown in both reactor stages was obtained. In the first stage, acetate and benzoate were degraded at a volumetric loading rate of 40 g-COD/L . day at a COD-removal efficiency of 95% within the first 25 days of operation. No degradation of terephthalate was obtained in the first stage during the first 300 days of operation despite operation of the reactor at a decreased volumetric loading rate with acetate and benzoate of 9 g-COD/L . day from day 150. Batch incubation of biomass from the reactor with terephthalate showed that the lag-phase prior to terephthalate degradation remained largely unchanged, indicating that no net growth of terephthalate degrading biomass occurred in the first stage reactor. From day 300, however, terephthalate degradation was observed in the first stage, and the biomass in this reactor could successfully be enriched with terephthalate degrading biomass, resulting in terephthalate removal capacities of 15 g-COD/L . day. Even though no single reason could be identified why (suddenly) terephthalate degradation was obtained after such a long period of operation, it is suggested that the solid retention time as well the prevailing reactor concentrations acetate and benzoate may have played an important role. From day 1 of operation, terephthalate was degraded in the second stage. In presence of methanogenic granular biomass, high terephthalate removal capacities were obtained in these reactors (15 g-COD/L . day) after approximately 125 days of operation. From the results obtained it is concluded that terephthalate degradation is the bottleneck during anaerobic treatment of PTA-wastewater. Pre-removal of acetate and benzoate in staged bioreactor reduces the lag-phase prior to terephthalate degradation in latter stages, and enables high rate treatment of PTA-wastewater. PMID:15889396

Kleerebezem, Robbert; Beckers, Judith; Hulshoff Pol, Look W; Lettinga, Gatze

2005-07-20

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

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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...

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

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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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

17

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)

2010-11-21

18

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)

2011-10-16

19

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)

2000-07-25

20

Direct electrospray ionization mass spectrometry quantitative analysis of sebacic and terephthalic acids in biodegradable polymers.  

Science.gov (United States)

A direct, rapid, and easy electrospray ionization mass spectrometry (ESI-MS) method to determine concentrations of sebacic acid (SA) and terephthalic acid (TA) residues in biodegradable copolymers was developed. Copolyester samples were synthesized from 1,4-butanediol and sebacic and terephthalic acids by melt polymerization. Extraction of monomers was performed in methanol. Their concentrations were determined by direct infusion ESI-MS, without chromatographic separation, using 1,12-dodecanedioic acid (DDA) as an internal standard. Calibration curves were obtained by plotting the ratio of the areas of the peaks relative to monomers and DDA standard as a function of their concentration ratio. We validated the method by determining the concentration of TA residue using both the ESI-MS protocol and high-performance liquid chromatography (HPLC) analysis with UV detection. The linearity range and the detection limit of this assay were 0.1-5.0 and 0.01 ppm for SA and 0.1-6.0 and 0.03 ppm for TA. This assay represents a useful alternative to conventional methods currently employed for acid quantification, resulting advantageous for its speed and high sensitivity. PMID:21204561

Rizzarelli, Paola; Zampino, Daniela; Ferreri, Loredana; Impallomeni, Giuseppe

2011-02-01

 
 
 
 
21

4-[(E)-2-(Pyridin-2-yl)ethenyl]pyridine–terephthalic acid (2/1)  

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The title 2:1 co-crystal, 2C12H10N2·C8H6O4, crystallizes with one molecule of 4-[(E)-2-(pyridin-2-yl)ethenyl]pyridine (A) and one half-molecule of terephthalic acid (B) in the asymmetric unit. In the crystal, the components are linked through heterodimeric COOH...Npyridine synthons, forming linear aggregates of composition –A–B–A–B–. Further linkage through weak C—H...O and C—H...? interactions gives two-dimensional hydrogen-bonded undulatin...

2012-01-01

22

4-[(E)-2-(Pyridin-2-yl)ethen­yl]pyridine–terephthalic acid (2/1)  

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The title 2:1 co-crystal, 2C12H10N2·C8H6O4, crystallizes with one mol­ecule of 4-[(E)-2-(pyridin-2-yl)ethen­yl]pyridine (A) and one half-mol­ecule of terephthalic acid (B) in the asymmetric unit. In the crystal, the components are linked through heterodimeric COOH?Npyridine synthons, forming linear aggregates of composition –A–B–A–B–. Further linkage through weak C—H?O and C—H?? inter­actions gives two-dimensional hydrogen-bonded undulating sheets propagating in the ...

2012-01-01

23

Surface-mediated nucleation in the solid-state polymorph transformation of terephthalic acid.  

Science.gov (United States)

A molecular mechanism for nucleation for the solid-state polymorph transformation of terephthalic acid is presented. New methods recently developed in our group, aimless shooting and likelihood maximization, are employed to construct a model for the reaction coordinate for the two system sizes studied. The reaction coordinate approximation is validated using the committor probability analysis. The transformation proceeds via a localized, elongated nucleus along the crystal edge formed by fluctuations in the supramolecular synthons, suggesting a nucleation and growth mechanism in the macroscopic system. PMID:17385859

Beckham, Gregg T; Peters, Baron; Starbuck, Cindy; Variankaval, Narayan; Trout, Bernhardt L

2007-04-18

24

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

2004-09-01

25

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

2006-01-01

26

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

27

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

28

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)

2010-11-21

29

Ultrafiltration membranes from waste polyethylene terephthalate and additives: synthesis and characterization  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english The synthesis and characterization of asymmetric ultrafiltration membranes from recycled polyethylene terephthalate (PET) and polyvinylpyrrolidone (PVP) is reported. PET is currently used in many applications, including the manufacture of bottles and tableware. Monomer extraction from waste PET is e [...] xpensive, and this process has not yet been successfully demonstrated on a viable scale. Hence, any method to recycle or regenerate PET once it has been used is of significant importance from scientific and environmental research viewpoints. Such a process would be a green alternative due to reduced raw monomer consumption and the additional benefit of reduced manufacturing costs. The membranes described here were prepared by a phase-inversion process, which involved casting a solution containing PET, m-cresol as solvent, and polyethylene glycol (PEG) of different molecular weights as additives. The membranes were characterized in terms of pure water permeability (PWP), molecular weight cut-off (MWCO), and flux and membrane morphology. The results show that the addition of PEG with high molecular weights leads to membranes with higher PWP. The presence of additives affects surface roughness and membrane morphology.

Smitha, Rajesh; Zagabathuni Venkata Panchakshari, Murthy.

30

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...

2008-01-01

31

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

32

Kinetic evaluation and process performance of an upflow anaerobic filter reactor degrading terephthalic acid.  

Science.gov (United States)

The anaerobic degradation of terephthalic acid (TA) as the sole organic carbon source was studied in an upflow anaerobic filter (UAF) reactor. The reactor was seeded with biomass obtained from a full-scale upflow anaerobic sludge bed (UASB) reactor and was used to treat wastewater from a petrochemical facility producing dimethyl terephthalate. The UAF reactor was operated for 252 d with a constant hydraulic retention time of 24 h, and the organic loading rate (OLR) was gradually increased from 1 to 10 g-chemical oxygen demand (COD)/L d. After a lag period of approximately 40 d, the COD removal efficiency increased exponentially and high removal rate values (?90%) were obtained, except for at highest OLR (10 g-COD/L d). The high removal rates and the robustness of the reactor performance could be attributed to the formation of biofilm as well as granular sludge. The methane production rates (0.22 to 2.15 L/d) correlated well with the removed OLRs (0.3 to 6.8 g-COD/L d) during the various phases of treatment, indicating that the main mechanism of TA degradation occurs via methanogenic reactions. The average methane content of the produced biogas was 70.3%. The modified Stover-Kincannon model was found to be applicable for the anaerobic degradation of TA in UAFs (Umax = 64.5, KB = 69.1 g-COD/L d and Ymax = 0.27 L-CH4/g-CODremoved). These results suggest that UAF reactors are among the most effective reactor configurations for the anaerobic degradation of TA. PMID:24960022

Davutluoglu, Orkun I; Seckin, Galip

2014-01-01

33

Pitting corrosion on 316L pipes in terephthalic acid (TA) dryer  

Energy Technology Data Exchange (ETDEWEB)

Grade 316L is a type of austenitic stainless steel with ultra-low carbon content and it exhibits superior corrosion resistance. However, pitting is always observed in 316L steel when it is exposed to media containing halide ions. In the present study, we found that in the presence of acetate acid (HAc) containing chloride or bromide ions, pitting occurred on the surface of the rotary steam pipes with the matrix material of 316L steel in terephthalic acid (TA) dryer. In order to identify the causes of the failure, metallographic structures and chemical compositions of the matrix material were inspected by an optical microscope (OM) and a photoelectric direct reading spectrometer. Beside these, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) as well as ion chromatography (IC) were used to analyze the micromorphologies of the corrosion pits and the chemical compositions of the corrosion deposits within them. Analysis of the results revealed the sources of halide ions and the factors accelerating the corrosion rate. Beside these, detailed mechanisms of pitting were discussed and six out of all the seven theoretical morphologies of pitting features were obtained in practice. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

Gong, Y.; Cao, J.; Meng, X.H.; Yang, Z.G. [Department of Materials Science, Fudan University, Shanghai (China)

2009-11-15

34

Investigation of hydrogen bonds properties in the terephthalic acid crystal, using molecular dynamics method.  

Science.gov (United States)

The aim of this study was to perform calculations using the method of Car-Parrinello molecular dynamics, leading to the optimized geometry of the molecules of 1,4-benzenedicarboxylic acid (terephthalic acid) in crystals, for the hydrogen form and three variants of substitution of deuterium atoms inside a carboxyl group. Based on the results, trajectories and dipole moments were calculated, what makes possible to simulate vibrations in different systems, and to make calculation of theoretical infrared spectra and atomic power spectra. Theoretical results were compared with the experimental spectra, which verifies the correctness of the method and also was compared with the results obtained by quantum-mechanical calculations using DFT for the isolated dimer. Comparison of the spectra of different forms, allowed for in-depth analysis of the effect of isotopic substitution on the frequency of vibrations and shapes of bands, and confirm the presence of possible coupling effects and intra- and intermolecular interactions. Comparison with the DFT results for the dimer show influence of the crystal structure on the spectra. PMID:24813277

Wierzbicka, Ewa; Boczar, Marek; Wójcik, Marek J

2014-09-15

35

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

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Synthesis, crystal structure, and porosity estimation of hydrated erbium terephthalate coordination polymers.  

Science.gov (United States)

The reaction of the Er3+ ion with polycarboxylate ligands in gel media leads to coordination polymers exhibiting various structural types and dimensionalities. Five Er3+/1,4-benzenedicarboxylate-based coordination polymers have been obtained in such conditions. Four out of the five are new. Their crystal structures are reported and compared herein. Compound 1, namely, Er2Ter3(H2O)6, where H2Ter symbolizes the terephthalic acid, crystallizes in the space group P1 (No. 2) with a = 7.8373(10) A, b = 9.5854(2) A, c = 10.6931(2) A, alpha = 68.7770(8) degrees, beta = 70.8710(8) degrees, and gamma = 75.3330(12) degrees. It has already been reported elsewhere. The last four compounds are new. Compound 2, namely, Er2Ter3(H2O)6 x 2 H2O, crystallizes in the space group P121/a1 (No. 14) with a = 6.7429(2) A, b = 22.4913(7) A, c = 9.6575(3) A, and beta = 91.6400(18) degrees. Compound 3, namely Er2Ter3(H2O)8 x 2 H2O crystallizes in the space group P1 (No. 2) with a = 7.5391(2) A, b = 10.0533(3) A, c = 10.4578(3) A, alpha = 87.7870(10) degrees, beta = 82.5510(11) degrees, and gamma = 86.2800(16) degrees. Compound 4, namely, Er2Ter3(H2O)6 x 2 H2O crystallizes in the space group C2/c (No. 15) with a = 38.5123(13) A, b = 11.1241(4) A, c = 7.0122(2) A, and beta = 98.634(2) degrees. Compound 5, namely, Er2Ter3(H2O)6 x H2O, crystallizes in the space group P1 (No. 2) with a = 6.8776(10) A, b = 11.0420(2) A, c = 18.5675(3) A, alpha = 84.7240(6) degrees, beta = 81.8380(6) degrees, and gamma = 84.1770(8) degrees. A computational method has also been developed to evaluate the potential porosity of the coordination polymers. This method is described and then applied to the different Er2Ter3(H2O)n coordination polymers previously described. PMID:16813403

Daiguebonne, Carole; Kerbellec, Nicolas; Bernot, Kevin; Gérault, Yves; Deluzet, André; Guillou, Olivier

2006-07-10

37

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

38

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

Directory of Open Access Journals (Sweden)

Full Text Available 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(OBu4 as a catalyst to get multiblock copolyesters. The chemical structure of the synthesized copolyesters was investigated by size exclusion chromatography (SEC and proton Nuclear Magnetic Resonance (1H NMR spectroscopy. Moreover the differential scanning calorimetry (DSC was used to explore their thermal properties. The ester-ester interchange reaction was observed between the two oligopolyesters, was studied and discussed in detail.

F. Malek

2014-08-01

39

Synthesis and characterization of azo acrylates grafted onto polyethylene terephthalate by gamma irradiation  

Energy Technology Data Exchange (ETDEWEB)

Polyethylene terephthalate (PET) films were grafted with acryloyl chloride by gamma irradiation, and the grafted films were reacted with Disperse Red 1 or 4-phenylazophenol. The films where characterized by atomic force microscopy, differential scanning calorimetry, FTIR-ATR, light polarized microscopy, elemental analysis and UV spectroscopy. The surface of the films was homogeneous, and the dye underwent trans to cis photoreaction, whereby the red films became colorless by the irradiation of UV light at room temperature.

Bucio, Emilio [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Circuito Exterior, Ciudad Universitaria, Mexico DF 04510 (Mexico)]. E-mail: ebucio@nucelares.unam.mx; Skewes, Phill [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Circuito Exterior, Ciudad Universitaria, Mexico DF 04510 (Mexico); Burillo, Guillermina [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Circuito Exterior, Ciudad Universitaria, Mexico DF 04510 (Mexico)

2005-07-01

40

Synthesis and characterization of azo acrylates grafted onto polyethylene terephthalate by gamma irradiation  

International Nuclear Information System (INIS)

Polyethylene terephthalate (PET) films were grafted with acryloyl chloride by gamma irradiation, and the grafted films were reacted with Disperse Red 1 or 4-phenylazophenol. The films where characterized by atomic force microscopy, differential scanning calorimetry, FTIR-ATR, light polarized microscopy, elemental analysis and UV spectroscopy. The surface of the films was homogeneous, and the dye underwent trans to cis photoreaction, whereby the red films became colorless by the irradiation of UV light at room temperature

2005-07-01

 
 
 
 
41

Design and synthesis of comonomers to enhance the optical, physical, and thermal properties of poly(ethylene terephthalate)  

Science.gov (United States)

Poly(ethylene terephthalate) (PET) is one of the world's most important commodity plastics. The largest volume applications of PET include textile fiber, tire cord, and packaging materials. There are many opportunities for improving the properties of PET that are associated with its various applications. We address three of the major application driven issues in PET: Increasing the optical brightness, increasing the crystallization rate, and enhancing the optical clarity through inhibition of crystallization. Each of the projects is summarized below. A new class of monomeric fused aromatic fluorescent brightening agents based on pyrene and anthracene have been designed and synthesized. The monomers: dimethyl 1,6-pyrene dicarboxylate, dimethyl 1,8-pyrenedicarboxylate, dimethyl 2,7-pyrenedicarboxylate, 1,9-bis(2-carboxybenzoyl)pyrene dimethyl ester, dimethyl 2,6-anthracenedicarboxylate, dimethyl 2,7-anthracenedicarboxylate and dimethyl 9,10-anthracenedicarboxylate were copolymerized with poly(ethylene terephthalate) and their optical properties were assessed. All of the polymers gave blue fluorescence with the copolymer containing dimethyl 1,6-pyrenedicarboxylate being the brightest. The synthesis of 2,7-substituted pyrene derivatives needed for the optical brightening project and for the crystallization rate enhancement project posed unique challenges. Optimized synthetic procedures for these compounds were developed. Pyrenes derivatized in the 2- and 7-positions were prepared by reduction of pyrene to 4,5,9,10-tetrahydropyrene followed by electrophilic aromatic substitution and re-aromatization. An optimized procedure is presented for hydrogenation of pyrene to provide 4,5,9,10-tetrahydropyene in high yield, which facilitates a convenient synthesis of dimethyl 2,7-pyrenedicarboxylate.

Connor, Daniel Martin

42

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

43

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.

2012-06-15

44

In situ synthesis of TiO{sub 2}/polyethylene terephthalate hybrid nanocomposites at low temperature  

Energy Technology Data Exchange (ETDEWEB)

TiO{sub 2} nanoflowers were in situ grown on polyethylene terephthalate (PET) non-woven fabric by hydrolysis of TiCl{sub 4} in aqueous solution in the presence of nanocrystal cellulose grafted PET fabric (NCC-g-PET) at a low temperature of 70 Degree-Sign 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 TiO{sub 2}. 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 TiO{sub 2} 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 TiO{sub 2}/PET hybrid nanocomposites exhibit excellent self-cleaning performance which is expected to have a good potential for commercialization.

Peng Xinyan [College of Materials Science and Engineering, South China University of Technology, Guangzhou, Guangdong 510640 (China); Ding Enyong, E-mail: eyding@scut.edu.cn [College of Materials Science and Engineering, South China University of Technology, Guangzhou, Guangdong 510640 (China); Xue Feng [College of Materials Science and Engineering, South China University of Technology, Guangzhou, Guangdong 510640 (China)

2012-06-15

45

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

46

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

47

Total synthesis of lysergic acid.  

Science.gov (United States)

A total synthesis of lysergic acid was accomplished. Key features of our synthesis include stereoselective construction of the stereogenic centers at the allylic positions by using the Evans aldol reaction, and a sequential process with a ring-closing metathesis and an intramolecular Heck reaction to construct the C and D rings. PMID:23919892

Umezaki, Satoshi; Yokoshima, Satoshi; Fukuyama, Tohru

2013-08-16

48

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...

2009-01-01

49

Gaseous species as reaction tracers in the solvothermal synthesis of the zinc oxide terephthalate MOF-5.  

Science.gov (United States)

Gaseous species emitted during the zinc oxide/zinc hydroxide 1,4-benzenedicarboxylate metal organic framework synthesis (MOF-5, MOF-69c) have been used to investigate the reaction scheme that leads to the framework creation. Changes of the gas-phase composition over time indicate that the decomposition of the solvent diethylformamide occurs at least via two competing reaction pathways that can be linked to the reaction's overall water and pH management. From isotope exchange experiments, we deduce that one of the decomposition pathways leads to the removal of water from the reaction mixture, which sets the conditions when the synthesis of an oxide-based (MOF-5) instead of an hydroxide-based MOF (MOF-69c) occurs. A quantitative account of most reactants and byproducts before and after the MOF-5/MOF-69c synthesis is presented. From the investigation of the reaction intermediates and byproducts, we derive a proposal of a basic reaction scheme for the standard synthesis zinc oxide carboxylate MOFs. PMID:17455926

Hausdorf, Steffen; Baitalow, Felix; Seidel, Jürgen; Mertens, Florian O R L

2007-05-24

50

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

51

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.

52

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

1995-01-01

53

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

54

Total synthesis of (+)-lysergic acid.  

Science.gov (United States)

We report the enantioselective total synthesis of (+)-lysergic acid using two different strategies, which featured three metal-catalyzed reactions for the construction of the BCD three rings, involving Pd-catalyzed indole synthesis for the construction of the B ring, a ring-closing metathesis reaction for the formation of the D ring, and an intramolecular Heck reaction to forge the C ring. In synthetic strategy I, the synthesis was achieved in 20 steps following the ring construction sequence of BDC. In synthetic strategy II, the synthetic route was shortened to only 12 steps by following the ring construction sequence of DBC and using a 4-chlorotryptophan derivative for the intramolecular Heck reaction. Moreover, we also discussed an unsuccessful synthetic strategy. PMID:24111583

Liu, Qiang; Zhang, Yu-An; Xu, Ping; Jia, Yanxing

2013-11-01

55

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

56

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

57

A Novel and Highly Regioselective Synthesis of New Carbamoylcarboxylic Acids from Dianhydrides  

Science.gov (United States)

A regioselective synthesis has been developed for the preparation of a series of N,N?-disubstituted 4,4?-carbonylbis(carbamoylbenzoic) acids and N,N?-disubstituted bis(carbamoyl) terephthalic acids by treatment of 3,3?,4,4?-benzophenonetetracarboxylic dianhydride (1) and 1,2,4,5-benzenetetracarboxylic dianhydride (2) with arylalkyl primary amines (A-N). The carbamoylcarboxylic acid derivatives were synthesized with good yield and high purity. The specific reaction conditions were established to obtain carbamoyl and carboxylic acid functionalities over the thermodynamically most favored imide group. Products derived from both anhydrides 1 and 2 were isolated as pure regioisomeric compounds under innovative experimental conditions. The chemo- and regioselectivity of products derived from dianhydrides were determined by NMR spectroscopy and confirmed by density functional theory (DFT). All products were characterized by NMR, FTIR, and MS.

Ochoa-Teran, Adrian; Estrada-Manjarrez, Jesus; Martinez-Quiroz, Marisela; Landey-Alvarez, Marco A.; Alcantar Zavala, Eleazar; Pina-Luis, Georgina; Santacruz Ortega, Hisila; Gomez-Pineda, Luis Enrique; Ramirez, Jose-Zeferino; Chavez, Daniel; Montes Avila, Julio; Labastida-Galvan, Victoria; Ordonez, Mario

2014-01-01

58

Low-cost, acid/alkaline-resistant, and fluorine-free superhydrophobic fabric coating from onionlike carbon microspheres converted from waste polyethylene terephthalate.  

Science.gov (United States)

Onionlike carbon microspheres composed of many nanoflakes have been prepared by pyrolyzing waste polyethylene terephthalate in supercritical carbon dioxide at 650 °C for 3 h followed by subsequent vacuum annealing at 1500 °C for 0.5 h. The obtained onionlike carbon microspheres have very high surface roughness and exhibit unique hydrophobic properties. Considering their structural similarities with a lotus leaf, we further developed a low-cost, acid/alkaline-resistant, and fluorine-free superhydrophobic coating strategy on fabrics by employing the onionlike carbon microspheres and polydimethylsiloxane as raw materials. This provides a novel technique to convert waste polyethylene terephthalate to valuable carbon materials. At the same time, we demonstrate a novel application direction of carbon materials by taking advantage of their unique structural properties. The combination of recycling waste solid materials as carbon feedstock for valuable carbon material production, with the generation of highly value-added products such as superhydrophobic fabrics, may provide a feasible solution for sustainable solid waste treatment. PMID:24502391

Hu, Haibo; Gao, Lei; Chen, Changle; Chen, Qianwang

2014-03-01

59

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

60

Hydroxamic acids in asymmetric synthesis.  

Science.gov (United States)

Metal-catalyzed stereoselective reactions are a central theme in organic chemistry research. In these reactions, the stereoselection is achieved predominantly by introducing chiral ligands at the metal catalyst's center. For decades, researchers have sought better chiral ligands for asymmetric catalysis and have made great progress. Nevertheless, to achieve optimal stereoselectivity and to catalyze new reactions, new chiral ligands are needed. Because of their high metal affinity, hydroxamic acids play major roles across a broad spectrum of fields from biochemistry to metal extraction. Dr. K. Barry Sharpless first revealed their potential as chiral ligands for asymmetric synthesis in 1977: He published the chiral vanadium-hydroxamic-acid-catalyzed, enantioselective epoxidation of allylic alcohols before his discovery of Sharpless asymmetric epoxidation, which uses the titanium-tartrate complex as the chiral reagent. However, researchers have reported few highly enantioselective reactions using metal-hydroxamic acid as catalysts since then. This Account summarizes our research on metal-catalyzed asymmetric epoxidation using hydroxamic acids as chiral ligands. We designed and synthesized a series of new hydroxamic acids, most notably the C2-symmetric bis-hydroxamic acid (BHA) family. V-BHA-catalyzed epoxidation of allylic and homoallylic alcohols achieved higher activity and stereoselectivity than Sharpless asymmetric epoxidation in many cases. Changing the metal species led to a series of unprecedented asymmetric epoxidation reactions, such as (i) single olefins and sulfides with Mo-BHA, (ii) homoallylic and bishomoallylic alcohols with Zr- and Hf-BHA, and (iii) N-alkenyl sulfonamides and N-sulfonyl imines with Hf-BHA. These reactions produce uniquely functionalized chiral epoxides with good yields and enantioselectivities. PMID:23157425

Li, Zhi; Yamamoto, Hisashi

2013-02-19

 
 
 
 
61

Modification of Poly(Ethylene Terephthalate) Fiber by Grafting of Acrylic Acid/Acrylamide for Removal of Pb+2 from Aqueous Solutions  

International Nuclear Information System (INIS)

A new fibrous adsorbent was prepared by grafting Acrylic Acid /Acryl Amide co-monomers onto Poly(Ethylene Terephthalate) fibers. The resulting sorbent has been characterized by Fourier Transform Infrared spectroscopy, Thermo Gravimetric Analysis, Scanning Electron Microscopy and elemental analysis and studied for the preconcentration and determination of trace Pb+2 ion from water sample. The effects of reaction conditions such as monomer mixture ratio, grafting yield, polymerization. The time and temperature on grafting were investigated. Batch adsorption method was used for the pre concentration studies. Recovery of Pb+2 was 100.2% at optimum conditions. The adsorption capacity of the adsorbent was found 44.1 mg/g for Pb+2.

2012-01-01

62

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.

2012-04-01

63

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

64

Performance and selectivity of the terephthalic acid probe for (OH)-O-center dot as a function of temperature, pH and composition of atmospherically relevant aqueous media  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In the present study, we investigated the performance and selectivity of terephthalic acid (TA) as a trapping molecule for the laboratory quantification of photogenerated (OH)-O-center dot in synthetic water (where the organic and inorganic concentration is perfectly controlled), adopted as a proxy of natural atmospheric water (i.e. cloud droplets). TA reacts with (OH)-O-center dot to yield 2-hydroxyterephthalic acid (TAOH). First, we focused our investigation on the reactivity of TA as a fun...

2011-01-01

65

An efficient total synthesis of trilepisiumic acid.  

Science.gov (United States)

Total synthesis of trilepisiumic acid (4-((3-(3,4-dihydroxyphenyl)acryloyl)oxy)-3-hydroxybenzoic acid) isolated from Trilepisium madagascariense was carried out. Doebner condensation of 3,4-dimethoxybenzaldehyde with malonic acid yielded 3,4-dimethoxycinnamic acid (2). Esterification of the latter with vanillin afforded 4-formyl-2-methoxyphenyl-3-(3,4-dimethoxy phenyl)acrylate (3) followed by permanganate oxidation in acidic medium provided the corresponding acid 4. Finally, demethylation of 4 was achieved by refluxing in hydrobromic acid to unveil the trilepisiumic acid (1). PMID:24841593

Saeed, Aamer; Qasim, Muhammad

2014-07-01

66

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 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.

2012-12-01

67

Fatty acid synthesis by spinach chloroplasts, 2  

International Nuclear Information System (INIS)

By incorporation of 3H2O into the fatty acid chain in the presence of unlabelled precursor, we showed that fatty acids are synthesized from PGA, PEP and pyruvate by intact spinach chloroplasts in the light. 13C-tracer experiments confirmed that 1-C of pyruvate is decarboxylated and 2-C is incorporated into fatty acids by the chloroplasts. The patterns of fatty acids synthesized from PGA and pyruvate were the same as that from acetate. The highest rate of fatty acid synthesis was reached at the physiological concentration of PGA (3 mM) and pyruvate (1 mM). These results indicate the operation of the following path in the chloroplasts in light: PGA?PEP?pyruvate?acetylCoA?fatty acids. Since citrate and OAA were much less active and malate and glyoxylate were inert as precursors for fatty acid synthesis, PEP or pyruvate carboxylation, citrate lyase reaction and malate synthetase reaction are not involved in the formation of acetylCoA and fatty acids. Since pyruvate was much more effective as a substrate for fatty acid synthesis than lactate, acetaldehyde or acetate, direct decarboxylation path is considered to be the primary path from pyruvate to acetylCoA. The insignificant effect of chloroplast-washing on fatty acid synthesis from PGA and pyruvate indicates that the glycolytic path from PGA to pyruvate is associated with the chloroplasts. Since pyruvate was more effectively incorporated into fatty acids than acetylCoA, it is unlikely that pyruvate decarboxylation to acetylCoA is due to mitochondria contaminating the chloroplast preparation. On the basis of measurements of 3H2O incorporation in the light and dark, the activity of fatty acid synthesis in spincah leaves appears to be shared by the activities in chloroplasts (87%) and other organelles (13%). (author)

1975-01-01

68

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

2008-01-01

69

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

70

Synthesis, crystal structures, and luminescence properties of carboxylate based rare-earth coordination polymers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Rare-earth coordination polymers or lanthanide-organic frameworks with hitherto unreported crystal structures have been obtained on the basis of the "light" lanthanides Pr, Nd, Sm, and Eu in combination with terephthalic acid and using a slightly altered literature synthesis procedure. Rietveld refinement has shown that powder XRD patterns of such compounds are largely dominated by the positions of the heavy elements, pointing to isostructural networks for all four terephthalate-based materia...

Decadt, Roel; Hecke, Kristof; Depla, Diederik; Leus, Karen; Weinberger, David; Driessche, Isabel; Voort, Pascal; Deun, Rik

2012-01-01

71

Synthesis of alpha-amino acids  

Science.gov (United States)

A method for synthesizing alpha amino acids proceding through novel intermediates of the formulas: R.sub.1 R.sub.2 C(OSOCl)CN, R.sub.1 R.sub.2 C(Cl)CN and [R.sub.1 R.sub.2 C(CN)O].sub.2 SO wherein R.sub.1 and R.sub.2 are each selected from hydrogen monovalent substituted and unsubstituted hydrocarbon radicals of 1 to 10 carbon atoms. The use of these intermediates allows the synthesis steps to be exothermic and results in an overall synthesis method which is faster than the snythesis methods of the prior art.

Davis, Jr., Jefferson W. (San Francisco, CA)

1983-01-01

72

Terephthalate salts: salts of monopositive cations  

Science.gov (United States)

The crystal structures of dilithium, disodium and diammonium terephthalate (1,4-benzenedicarboxylate) have been solved ab initio using Monte Carlo simulated annealing techniques, and refined using synchrotron powder data. The structures of dipotassium terephthalate, potassium hydrogen terephthalate and ammonium hydrogen terephthalate have been refined using single-crystal techniques. Li2C8H4O4 crystallizes in P2(1)/c, with a = 8.35921 (5), b = 5.13208 (2), c = 8.48490 (5) A, beta = 93.1552 (4) degrees, V = 363.451 (3) A3, Z = 2. The Li anions are tetrahedrally coordinated and the packing of the terephthalate anions resembles the gamma-packing of aromatic hydrocarbons. Na2C8H4O4 crystallizes in Pbc2(1), with a = 3.54804 (5), b = 10.81604 (16), c = 18.99430 (20) A, V = 728.92 (2) A3, Z = 4. The coordination of the two independent Na is trigonal prismatic and the terephthalate packing resembles the beta packing of hydrocarbons. (NH4)2C8H4O4 also crystallizes in Pbc2(1), with a = 4.0053 (5), b = 11.8136 (21), c = 20.1857 (24) A, V = 955.1 (2) A3, Z = 4. The cations and planar anions are linked by hydrogen bonds and the packing is a looser version of the beta packing. K2C8H4O2 crystallizes in P2(1)/c, with a = 10.561 (4), b = 3.9440 (12), c = 11.535 (5) A, beta = 113.08 (3) degrees, V = 442.0 (3) A3, Z = 2. The K is trigonal prismatic and the packing is also beta. Both KHC8H4O4 and (NH4)HC8H4O4 crystallize in C2/c, with a = 18.825 (4) and 18.924 (4), b = 3.770 (2) and 3.7967 (9), c = 11.179 (2) and 11.481 (2) A, beta = 98.04 (3) and 94.56 (5) degrees, V = 816.8 (3) and 790.9 (3) A3, respectively, and Z = 4. The packing in the hydrogen-bonded acid salts is also beta. Electrostatic interactions among the terephthalate anions appear to be important in determining the crystal packing. PMID:10877356

Kaduk

2000-06-01

73

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

74

Synthesis of alpha-amino acids  

Energy Technology Data Exchange (ETDEWEB)

A method is described for synthesizing alpha amino acids proceeding through novel intermediates of the formulas: R/sub 1/R/sub 2/C(OSOCl)C/sub n/, R/sub 1/R/sub 2/C(Cl)C/sub n/ and (R/sub 1/R/sub 2/C(C/sub n/)O)2SO wherein R/sub 1/ and R/sub 2/ are each selected from hydrogen monovalent substituted and unsubstituted hydrocarbon radicals of 1 to 12 carbon atoms. The use of these intermediates allows the synthesis steps to be exothermic and results in an overall synthesis method which is faster than the synthesis methods of the prior art.

Davis, J.W.

1983-03-01

75

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.

2012-02-15

76

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

77

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)

2005-01-01

78

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

79

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

2013-07-25

80

5-Aminolevulinic acid synthesis in Escherichia coli.  

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A hemA mutant of Escherichia coli containing a multicopy plasmid which complemented the mutation excreted 5-aminolevulinic acid (ALA) into the medium. [1-14C]glutamate was substantially incorporated into ALA by this strain, whereas [2-14C]glycine was not. Periodate degradation of labeled ALA showed that C-5 of ALA was derived from C-1 of glutamate. The synthesis of ALA by two sonicate fractions which had been processed by gel filtration and dialysis, respectively, was dependent on glutamate, ...

Li, J. M.; Brathwaite, O.; Cosloy, S. D.; Russell, C. S.

1989-01-01

 
 
 
 
81

Radiation chemistry of the terephthalate dosimeter  

International Nuclear Information System (INIS)

Cobalt-60 ?-irradiated aqueous sodium terephthalate solutions have been studied; in aerated 4 x 10-4 M sodium hydroxide solutions, the main products are hydroxyterephthalate (HTA) (G = 0.99 +- 0.01), carbonate (G = 1.31 +- 0.08), and peroxides (G = 2.84 +- 0.04). The HTA and carbonate species are formed by hydroxyl radical attack and account for approximately 90% of hydroxyl radical reactions. The ortho-, meta-, and para-hydroxybenzoic acids, if formed at all, cannot have G values greater than 0.03, 0.10, and 0.27, respectively; their formation in concentrations corresponding to the maximum yields will not contribute significantly to the fluorescence attributed to the HTA. Oxygen must be present for efficient conversion of the terephthalate-OH radical adduct to HTA, and oxygenation increases G(HTA) above the aerated solution value; but no evidence was found for HTA and CO2 formation from primary radiolytic species other than the hydroxyl radical. G(HTA) is unaffected by changes in terephthalate concentration between 1 x 10-4 and 1 x 10-2 M in sodium hydroxide solutions at pH 10, but it is affected in the solution pH is decreased. In phosphate-buffered solutions at pH 6.85, G(HTA) is 0.93 +- 0.01; a further decrease in solution pH yields lower values. The lowering of the G(HTA) value is attributed to recombination reactions between the terephthalate-OH radical products and reducing radical products. Support for the recombination postulate was obtained from measurement of a parallel decrease in the peroxide yield and the observation of a dose-rate efect on G(HTA). Competition kinetic studies with added solutes carbonate and bicarbonate gave the rate ratios k(OH + TA2-):k(OH + CO32-):k(OH + HCO3-) = 1:0.106:0.0036

1980-01-01

82

Microwave irradiated synthesis and characterization of 1, 4-phenylene bis-oxazoline form bis-(2-hydroxyethyl terephthalamide obtained by depolymerization of poly (ethylene terephthalate (PET bottle wastes  

Directory of Open Access Journals (Sweden)

Full Text Available The aminolytic depolymerization of PET bottle waste with ethanolamine by conventional heating and microwave irradiation heating method was attempted with heterogeneous, recyclable acid catalysts such as beta zeolite (SiO2/ AlO2= 15 Na- form and montmorillonite KSF. The pure product bis-(2-hydroxyethyl terephthalamide (BHETA of aminolysis was obtained in good yield (85- 88%. The BHETA, thus obtained, was subjected to cyclization reaction by heating with polyphosphoric acid as well as by chlorination (using phosphoryl chloride, bromination (using red phosphorous and liquid bromine and nitration (conc. HNO3 + conc. H2SO4 followed by conventional and microwave irradiation heating in N,N- dimethyl formamide/ potassium carbonate solution. The product so obtained was 2, 2’-(1,4-phenylene–bis-(2-oxazoline (PBO, which has applications in polymer synthesis as a chain extender/ chain coupling agent or a cross linker. The productswere analyzed by FTIR, DSC, Mass and NMR (1H and 13C NMR.

Yogesh S. Parab

2012-04-01

83

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 "1"4C 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-"1"4C 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 "1"4C 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 "1"4C protein at 30 minutes as compared to the synthesis of "1"4C protein without N-carbamoyl-amino acids. These results indicate that the presence of carbamoyl-amino acids interferes with protein synthesis

1987-05-01

84

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

85

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.

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

86

Catalysis of the Carbonylation of Alcohols to Carboxylic Acids Including Acetic Acid Synthesis from Methanol.  

Science.gov (United States)

Monsanto's highly successful synthesis of acetic acid from methanol and carbon monoxide illustrates use of new starting materials to replace pretroleum-derived ethylene. Outlines the fundamental aspects of the acetic acid process and suggests ways of extending the synthesis to higher carboxylic acids. (JN)

Forster, Denis; DeKleva, Thomas W.

1986-01-01

87

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

1976-01-01

88

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

89

On the Diels-Alder approach to solely biomass-derived polyethylene terephthalate (PET): conversion of 2,5-dimethylfuran and acrolein into p-xylene.  

Science.gov (United States)

Polyethylene terephthalate (PET) is a polymeric material with high global demand. Conventionally, PET is produced from fossil-fuel-based materials. Herein, we explored the feasibility of a sustainable method for PET production by using solely bio-renewable resources. Specifically, 2,5-dimethylfuran (derived from lignocellulosic biomass through 5-(hydroxymethyl)furfural) and acrolein (produced from glycerol, a side product of biodiesel production) were converted into the key intermediate p-xylene (a precursor of terephthalic acid). This synthesis consists of a sequential Diels-Alder reaction, oxidation, dehydration, and decarboxylation. In particular, the pivotal first step, the Diels-Alder reaction, was studied in detail to provide useful kinetic and thermodynamic data. Although it was found that this reaction requires low temperature to proceed efficiently, which presents a limitation on economic feasibility on an industrial scale, the concept was realized and bio-derived p-xylene was obtained in 34% overall yield over four steps. PMID:21922576

Shiramizu, Mika; Toste, F Dean

2011-10-24

90

Fatty acid synthesis by spinach chloroplasts, 1  

International Nuclear Information System (INIS)

Intact chloroplasts (about 70% Class I chloroplasts) isolated from spinach leaves incorporated 150 nmoles of [1-14C] acetate into fatty acids per mg chlorophyll in 1 hr at pH 8.3, 250C and 25,000 lux. On electron and phase-contrast microscopies combined with hypotonic treatment of chloroplasts, this synthetic activity was shown to be proportional to the percentage of Class I chloroplasts in the preparation. Light was necessary for the synthesis, the activity in the complete reaction mixture in the dark being only 2% of that in the light. The synthetic activity increased with increasing intensities of light to reach saturation at 6000 lux. CoA and ATP were most effective as cofactors, HCO3-, HPO42-, Mg2+ and Mn2+ were less effective. ATP could be replaced by ADP in the presence of Pi, suggesting possible supply of ATP by photophosphorylation. Omission of the NADPH-generation system and NADH did not affect the synthesis, indicating sufficient provision of endogenous NADPH and NADH in intact chloroplasts under light. Addition of DTE did not cause recovery of the synthetic activity of intact chloroplasts in the dark. (author)

1975-01-01

91

A simple synthesis of propionic-3-14C acid  

International Nuclear Information System (INIS)

Propionic-3-14C acid was prepared by methylation of tricarbethoxymethane and subsequent hydrolysis. This method avoids the problems of malonic ester synthesis. A pure monoalkyl derivative was obtained. (author)

1981-01-01

92

Proton and deuterium NMR experiments in zero field. [Perdeuterated p-demethoxybenzene, perdeuterated malonic acid, diethyl terephthalate-d4, nonadecane-2,2'-D2, sodium propionate-D2  

Energy Technology Data Exchange (ETDEWEB)

High field solid-state NMR lineshapes suffer from inhomogeneous broadening since resonance frequencies are a function of molecular orientation. Time domain zero field NMR is a two-dimensional field-cycling technique which removes this broadening by probing the evolution of the spin system under zero applied field. The simplest version, the sudden transition experiment, induces zero field evolution by the sudden removal of the applied magnetic field. Theory and experimental results of this experiment and several variations using pulsed dc magnetic fuelds to initiate zero field evolution are presented. In particular, the pulsed indirect detection method allows detection of the zero field spectrum of one nuclear spin species via another (usually protons) by utilizing the level crossings which occur upon adiabatic demagnetization to zero field. Experimental examples of proton/deuteron systems are presented which demonstrate the method results in enhanced sensitivity relative to that obtained in sudden transition experiments performed directly on deuterium. High resolution /sup 2/H NQR spectra of a series of benzoic acid derivatives are obtained using the sudden transition and indirect detection methods. Librational oscillations in the water molecules of barium chlorate monohydrate are studied using proton and deuterium ZF experiments. 177 refs., 88 figs., 2 tabs.

Millar, J.M.

1986-02-01

93

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

94

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

95

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...

2012-01-01

96

Poli(tereftalato de etileno), PET: uma revisão sobre os processos de síntese, mecanismos de degradação e sua reciclagem / Poly(ethylene terephthalate), PET: a review on the synthesis processes, degradation mechanisms and its recycling  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Apresentamos uma revisão sobre o poli(tereftalato de etileno) enfatizando os processos de síntese e os mecanismos de degradação. Atualmente o Brasil apresenta um dos maiores índices mundiais de reciclagem mecânica deste polímero, correspondendo a um percentual de 53%. O sucesso desse termoplástico n [...] a indústria de reciclagem deve-se à sua ampla diversidade de aplicações, desde a indústria têxtil (multifilamento) até as indústrias de alimentos, onde as embalagens recicladas grau alimentício poderão ser misturadas com a resina virgem em diversas proporções e reprocessadas para o uso. Uma abordagem sobre a atual legislação do uso de PET reciclado em contato com alimentos também é mostrada neste trabalho. No processo de síntese do PET realizado em duas ou três etapas, são usados comonômeros e aditivos para otimizar as condições de processamento do material. Entretanto, tanto durante a síntese como no processo de reciclagem, ocorrem reações de degradação (termomecânica e termo-oxidativa) e reações secundárias, formando acetaldeído, oligômeros, e o dietileno glicol. A presença desses "contaminantes" acelera o processo de degradação do polímero, afetando a qualidade do produto final. Abstract in english We present a review on poly(ethylene terephthalate), emphasizing the synthesis processes and the degradation mechanisms. Brazil is currently among the countries that most recycle PET, with 53% of this polymer being mechanically recycled. The success of this thermoplastic in the recycling industry is [...] due to its large diversity of applications, from the textile industry to food packaging, where the food grade recycled packages will be mixed with the pristine resin for reprocessing and use. We also discuss the present legal aspects concerning PET recycling and its use in contact with food. In the synthesis of PET, usually done in two or three steps, several co-monomers and additives are used to optimize the final properties and processing conditions. Additionally, during the synthesis, processing and recycling, several degradation (thermomechanical and thermo-oxidation) and secondary reactions occur, producing acetaldehydes, oligomers and diethyleneglicol. The presence of these "contaminants" accelerates the degradation process of the polymer affecting the final product characteristics.

Romão, Wanderson; Spinacé, Márcia A. S.; Paoli, Marco-A. De.

97

Poli(tereftalato de etileno, PET: uma revisão sobre os processos de síntese, mecanismos de degradação e sua reciclagem Poly(ethylene terephthalate, PET: a review on the synthesis processes, degradation mechanisms and its recycling  

Directory of Open Access Journals (Sweden)

Full Text Available Apresentamos uma revisão sobre o poli(tereftalato de etileno enfatizando os processos de síntese e os mecanismos de degradação. Atualmente o Brasil apresenta um dos maiores índices mundiais de reciclagem mecânica deste polímero, correspondendo a um percentual de 53%. O sucesso desse termoplástico na indústria de reciclagem deve-se à sua ampla diversidade de aplicações, desde a indústria têxtil (multifilamento até as indústrias de alimentos, onde as embalagens recicladas grau alimentício poderão ser misturadas com a resina virgem em diversas proporções e reprocessadas para o uso. Uma abordagem sobre a atual legislação do uso de PET reciclado em contato com alimentos também é mostrada neste trabalho. No processo de síntese do PET realizado em duas ou três etapas, são usados comonômeros e aditivos para otimizar as condições de processamento do material. Entretanto, tanto durante a síntese como no processo de reciclagem, ocorrem reações de degradação (termomecânica e termo-oxidativa e reações secundárias, formando acetaldeído, oligômeros, e o dietileno glicol. A presença desses "contaminantes" acelera o processo de degradação do polímero, afetando a qualidade do produto final.We present a review on poly(ethylene terephthalate, emphasizing the synthesis processes and the degradation mechanisms. Brazil is currently among the countries that most recycle PET, with 53% of this polymer being mechanically recycled. The success of this thermoplastic in the recycling industry is due to its large diversity of applications, from the textile industry to food packaging, where the food grade recycled packages will be mixed with the pristine resin for reprocessing and use. We also discuss the present legal aspects concerning PET recycling and its use in contact with food. In the synthesis of PET, usually done in two or three steps, several co-monomers and additives are used to optimize the final properties and processing conditions. Additionally, during the synthesis, processing and recycling, several degradation (thermomechanical and thermo-oxidation and secondary reactions occur, producing acetaldehydes, oligomers and diethyleneglicol. The presence of these "contaminants" accelerates the degradation process of the polymer affecting the final product characteristics.

Wanderson Romão

2009-06-01

98

Lysophosphatidic acid synthesis and phospholipid metabolism in rat mast cells  

Energy Technology Data Exchange (ETDEWEB)

The role of lysophosphatidic acid in mast cell response to antigen was investigated using an isolated rat serosal mast cell model. The cells were incubated with monoclonal murine immunoglobulin E to the dinitrophenyl hapten and prelabeled with /sup 32/P-orthophosphate or /sup 3/H-fatty acids. Lysophosphatidic acid was isolated form cell extracts by 2-dimensional thin-layer chromatography, and the incorporated radioactivity was assessed by liquid scintillation counting. Lysophosphatidic acid labeling with /sup 32/P was increased 2-4 fold within 5 minutes after the addition of antigen or three other mast cell agonists. Functional group analyses unequivocally showed that the labeled compound was lysophosphatidic acid. Lysophosphatidic acid synthesis was dependent on the activity of diacylglycerol lipase, suggesting formation from monoacylglycerol. In addition, the studies of lysophosphatidic acid synthesis suggest that the addition of antigen to mast cells may initiate more than one route of phospholipid degradation and resynthesis. Whatever the origin of lysophosphatidic acid, the results of this study demonstrated that lysophosphatidic acid synthesis is stimulated by a variety of mast cell agonists. Dose-response, kinetic, and pharmacologic studies showed close concordance between histamine release and lysophosphatidic acid labeling responses. These observations provide strong evidence that lysophosphatidic acid plays an important role in mast cell activation.

Fagan, D.L.

1986-01-01

99

Lysophosphatidic acid synthesis and phospholipid metabolism in rat mast cells  

International Nuclear Information System (INIS)

The role of lysophosphatidic acid in mast cell response to antigen was investigated using an isolated rat serosal mast cell model. The cells were incubated with monoclonal murine immunoglobulin E to the dinitrophenyl hapten and prelabeled with "3"2P-orthophosphate or "3H-fatty acids. Lysophosphatidic acid was isolated form cell extracts by 2-dimensional thin-layer chromatography, and the incorporated radioactivity was assessed by liquid scintillation counting. Lysophosphatidic acid labeling with "3"2P was increased 2-4 fold within 5 minutes after the addition of antigen or three other mast cell agonists. Functional group analyses unequivocally showed that the labeled compound was lysophosphatidic acid. Lysophosphatidic acid synthesis was dependent on the activity of diacylglycerol lipase, suggesting formation from monoacylglycerol. In addition, the studies of lysophosphatidic acid synthesis suggest that the addition of antigen to mast cells may initiate more than one route of phospholipid degradation and resynthesis. Whatever the origin of lysophosphatidic acid, the results of this study demonstrated that lysophosphatidic acid synthesis is stimulated by a variety of mast cell agonists. Dose-response, kinetic, and pharmacologic studies showed close concordance between histamine release and lysophosphatidic acid labeling responses. These observations provide strong evidence that lysophosphatidic acid plays an important role in mast cell activation

1986-01-01

100

Synthesis and antimicrobial activity of some anthranilic acid derivatives.  

Science.gov (United States)

The synthesis of eight derivatives of anthranilic acid is described. Investigation of their antimicrobial activity showed that four of the compounds, viz; anthranilohydrazide, 3,4-dihydro-4-oxo-1,2,3-benzotriazine, triazine-beta-naphthol adduct and N-phenyl anthranilic acid showed significant antibacterial activity. None of the compounds showed any noticeable antifungal effect. PMID:7433494

Kar, A; Gugnani, H C; Madumere, U A

1980-08-01

 
 
 
 
101

Tunable acid-sensitive ester protecting groups in oligosaccharide synthesis.  

Science.gov (United States)

A series of acid-cleavable ester-type protecting groups, with acid-sensitivity profiles parallel to those of 2-naphthylmethyl (NAP) or p-methoxybenzyl (PMB) ether, were designed and TFA in toluene was identified as a technically simple and effective deblocking cocktail for their global removal in the context of oligosaccharide synthesis. PMID:24519721

Li, Yao; Liu, Xinyu

2014-03-25

102

Ferrocene-containing nucleic acids. Synthesis and electrochemical properties  

Energy Technology Data Exchange (ETDEWEB)

The published data on the synthesis of ferrocene-containing nucleic acid fragments are generalised. The known methods are systematised and their advantages and disadvantages are discussed. The use of nucleoside, nucleotide and oligonucleotide conjugates with ferrocene in the design of systems for electrochemical detection of nucleic acids is considered.

Zatsepin, Timofei S; Andreev, Sergei Yu; Oretskaya, Tat' yana S [Department of Chemistry, M.V. Lomonosov Moscow State University, Moscow (Russian Federation); Hianik, T [Comenius University (Slovakia)

2003-06-30

103

Synthesis of the ?, ?-Dicarboxylic Acid Precursor of Biotin by the Canonical Fatty Acid Biosynthetic Pathway  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Biotin synthesis requires the C7 ?, ?-dicarboxylic acid, pimelic acid. Although pimelic acid was known to be primarily synthesized by a head to tail incorporation of acetate units, the synthetic mechanism was unknown. It has recently been demonstrated that in most bacteria the biotin pimelate moiety is synthesized by a modified fatty acid synthetic pathway in which the biotin synthetic intermediates are O-methyl esters disguised to resemble the canonical intermediates of the fatty acid synt...

Cronan, John E.; Lin, Steven

2011-01-01

104

The Two Carboxylases of Corynebacterium glutamicum Essential for Fatty Acid and Mycolic Acid Synthesis? †  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The suborder Corynebacterianeae comprises bacteria like Mycobacterium tuberculosis and Corynebacterium glutamicum, and these bacteria contain in addition to the linear fatty acids, unique ?-branched ?-hydroxy fatty acids, called mycolic acids. Whereas acetyl-coenzyme A (CoA) carboxylase activity is required to provide malonyl-CoA for fatty acid synthesis, a new type of carboxylase is apparently additionally present in these bacteria. It activates the ?-carbon of a linear fatty acid by carb...

2007-01-01

105

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

Energy Technology Data Exchange (ETDEWEB)

The facile synthesis of lithocholic acid 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 to 1 hr. Taurolithocholic acid sulfate was obtained by conjugating lithcoholic acid sulfate with taurine in dimethylformamide at 90/sup 0/C for 0.5 hr. The one-pot synthesis of taurolithocholic acid sulfate starting from lithocholic acid is also described. This proceudre, 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.

Tserng, K.Y.; Klein, P.D.

1977-07-01

106

Synthesis of [1-14C] palmitic acid  

International Nuclear Information System (INIS)

The synthesis of [1-14C] palmitic acid via Grignard Reaction is reported. The carbon-C14 dioxide was liberated by dropping sulfuric acid onto barium carbonate-C14. The yield of [1-14C] palmitic acid was 44.8%. A radiochemical purity of more than 99.5% was determined by HPLC and the product was proved to be free of impurity by TLC

1997-09-01

107

Fatty acid synthesis is inhibited by inefficient utilization of unusual fatty acids for glycerolipid assembly.  

Science.gov (United States)

Degradation of unusual fatty acids through ?-oxidation within transgenic plants has long been hypothesized as a major factor limiting the production of industrially useful unusual fatty acids in seed oils. Arabidopsis seeds expressing the castor fatty acid hydroxylase accumulate hydroxylated fatty acids up to 17% of total fatty acids in seed triacylglycerols; however, total seed oil is also reduced up to 50%. Investigations into the cause of the reduced oil phenotype through in vivo [(14)C]acetate and [(3)H]2O metabolic labeling of developing seeds surprisingly revealed that the rate of de novo fatty acid synthesis within the transgenic seeds was approximately half that of control seeds. RNAseq analysis indicated no changes in expression of fatty acid synthesis genes in hydroxylase-expressing plants. However, differential [(14)C]acetate and [(14)C]malonate metabolic labeling of hydroxylase-expressing seeds indicated the in vivo acetyl-CoA carboxylase activity was reduced to approximately half that of control seeds. Therefore, the reduction of oil content in the transgenic seeds is consistent with reduced de novo fatty acid synthesis in the plastid rather than fatty acid degradation. Intriguingly, the coexpression of triacylglycerol synthesis isozymes from castor along with the fatty acid hydroxylase alleviated the reduced acetyl-CoA carboxylase activity, restored the rate of fatty acid synthesis, and the accumulation of seed oil was substantially recovered. Together these results suggest a previously unidentified mechanism that detects inefficient utilization of unusual fatty acids within the endoplasmic reticulum and activates an endogenous pathway for posttranslational reduction of fatty acid synthesis within the plastid. PMID:24398521

Bates, Philip D; Johnson, Sean R; Cao, Xia; Li, Jia; Nam, Jeong-Won; Jaworski, Jan G; Ohlrogge, John B; Browse, John

2014-01-21

108

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 bile acid synthesis in man

1988-01-01

109

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

110

Fatty Acid Synthesis by Indonesian Marine Diatom, Chaetoceros gracilis  

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Full Text Available 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 increased significantly from the stationary phase to the death phase, but not significantly from the end exponential phase to the stationary phase. The relative percentage of saturated fatty acid (SAFA of the total fatty acid was higher than that of monounsaturated fatty acid (MUFA and polyunsaturated fatty acid (PUFA at all of growth phase. The highest PUFA was found at stationary phase at the same time when SAFA was being the lowest. The majority of SAFA was palmitic acid (24.03-40.35%. MUFA contained significant proportion of oleic acid (19.6-20.9%. Oleic acid, linoleic acid and ?-linolenic acid were found at every stage growth. These fatty acids are considered as precursor for production of long chain PUFA-Docosahexaenoic acid (DHA/22:6?3 through series of desaturation and elongation step with all of desaturase enzyme (?8-D, ?9-D, ?12-D, ?15-D, ?17-D, ?6-D, ?5-D, and ?4-D and elongase enzyme (E.

ALBERTA RIKA PRATIWI

2009-12-01

111

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

112

Tuning Gold Nanorod Synthesis through Prereduction with Salicylic Acid  

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Successful synthesis of gold nanorods requires subtle combination of additives and reducing species. The latter are of major importance, as the reducing power determines the rate of metallic gold formation, which often defines the final shape and anisotropy. Ascorbic acid is a common reducing agent in the synthesis of gold nanorods, but its relatively strong reducing power limits the tunability of the final shape and optical response. We propose here a bimodal reducing agent system comprising...

2013-01-01

113

Improvement on synthesis of different alkyl-phenylboronic acid.  

Science.gov (United States)

Various alkyl-phenylboronic acids have been widely used in the fields of electronics, chemistry, medicine and biology, especially in glucose sensors and intermediates of medicines. In this paper, the syntheses of two or three different alkyl-phenylboronic acids and the improvement on synthesis processes were studied with Grignard reagent method in detail. The influencing factors such as temperature, reaction time, reactant molar ratio were analyzed with the orthogonal experiment; optimized processes for the preparation of different alkyl-phenylboronic acids were thus obtained using different alkylborates as original materials. Based on the analysis of the experiment results, a "one-pot" method was proposed and checked to synthesize several different alkyl-phenylboronic acids. It was shown that 2,6-dimethylphenylboronic acid could be synthesized with "one-pot" method while para-alkyl-phenylboronic acid could not. An optimized process for the synthesis of 2,6-dimethylphenylboronic acid was obtained by investigating the influence of the boronation reagent, reactant proportion and solvent on the yield. Meanwhile, the preliminary synthesis of 2-ethylphenylboric acid was investigated with "one-pot" method too. Each product was identified by mass spectrum, 1HNMR, IR and HPLC. PMID:20201431

Deng, Yan; Zhang, Yongqiang; Jiang, Huanmei; Xu, Lijian; Liu, Hongna; Li, Song; He, Nongyue

2009-10-01

114

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)

2010-01-01

115

Synthesis and Carbohydrate Binding Studies of Fluorescent ?-Amidoboronic Acids and the Corresponding Bisboronic Acids  

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Fluorescent boronic acids are very useful for the design and synthesis of carbohydrate sensors. In an earlier communication, we first described the effort of developing water soluble fluorescent ?-amidoboronic acids, which change fluorescence upon sugar binding. In this report, we describe a general method of functionalizing such boronic acids and their applications in the preparation of bis-?-amidoboronic acids with significantly enhanced binding for oligosaccharides as compared to their m...

Jin, Shan; Zhu, Chunyuan; Cheng, Yunfeng; Li, Minyong; Wang, Binghe

2010-01-01

116

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

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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

117

Catalytic methylenedianiline synthesis on porous solid acids  

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Methylenedianiline (MDA) is an important raw material for the production of polyurethanes, synthesized from aniline and formaldehyde by an acid catalyzed reaction. Currently HCl is applied as catalyst. Replacing mineral acids by solid acids is of considerable interest for transforming processes towards green chemistry. In this work the SN2-type reaction mechanism and the reaction network of the formation of MDA over solid acid catalysts has been elucidated. The influence of pore size and geom...

Salzinger, Michael

2010-01-01

118

Acetylsalicylic acid: Incoming 150 years of the first synthesis  

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Full Text Available 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 acetylsalicylic acid. Felix Hoffmann, a chemist for Friedrich Bayer, a German dye company obtained a patent on acetylsalicylic acid some 40 years later. Bayer coined the name Aspirin for the new product. The 20 in century was the century in which many researchers in many companies tried to improve the synthesis of acetylsalicylic acid not only in terms of yield but also purity. This paper describes the history, use, mechanism of action, synthesis and production as well as the purification and stability of acetylsalicylic acid.

Mijin Dušan Ž.

2002-01-01

119

Synthesis of novel tritium labeled oxamyristic acids  

International Nuclear Information System (INIS)

Syntheses of [3H]-labeled 13-oxa (5) and 6-oxa (9) myristic acids with specific activity of 137 Ci/mmol and 105 Ci/mmol respectively, starting from the corresponding acetylenic precursors, 12-methoxy-10-dodecynoic acid (4) and 5-(3-octynyloxy)pentanoic acid (8) are described. The precursor 4 is readily obtained in high yield by alkylation of the lithium salt of methyl propargyl ether with 9-iodononanoic acid, whereas 8 is obtained by alkylation of 3-octyn-1-ol with t-butyl-5-bromovalerate under phase transfer conditions, followed by acid catalysed removal of the t-butyl group. (author)

1991-01-01

120

Amino Acid Synthesis in a Supercritical Carbon Dioxide - Water System  

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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...

2009-01-01

 
 
 
 
121

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)

2009-10-13

122

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)

2002-10-15

123

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

124

Cancer chemotherapy: targeting folic acid synthesis  

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Antifolates are structural analogs of folates, essential one-carbon donors in the synthesis of DNA in mammalian cells. Antifolates are inhibitors of key enzymes in folate metabolism, namely dihydrofolate reductase, ?-glycinamide ribonucleotide transformylase, 5?-amino-4?-imidazolecarboxamide ribonucleotide transformylase, and thymidylate synthetase. Methotrexate is one of the earliest anticancer drugs and is extensively used in lymphoma, acute lymphoblastic leukemia, and osteosarcoma, am...

Hagner, Nicole; Joerger, Markus

2010-01-01

125

Inhibitory effect of novobiocin on ribonucleic acid synthesis during germination of Bacillus subtilis spores.  

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Novobiocin inhibited ribonculeic acid synthesis during germination of Bacillus subtilis spores. Transcription of certain kinds of genes probably required a preceding conformational change in deoxyribonucleic acid.

Matsuda, M.; Kameyama, T.

1980-01-01

126

An efficient synthesis of tetramic acid derivatives with extended conjugation from L-Ascorbic Acid  

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Full Text Available Abstract Background Tetramic acids with polyenyl substituents are an important class of compounds in medicinal chemistry. Both solid and solution phase syntheses of such molecules have been reported recently. Thiolactomycin, a clinical candidate for treatment of tuberculosis has led to further explorations in this class. We have recently developed an efficient synthesis of tetramic acids derivatives from L- ascorbic acid. In continuation of this work, we have synthesised dienyl tetramic acid derivatives. Results 5,6-O-Isopropylidene-ascorbic acid on reaction with DBU led to the formation of tetronolactonyl allyl alcohol, which on oxidation with pyridinium chlorochromate gave the respective tetranolactonyl allylic aldehydes. Wittig olefination followed by reaction of the resulting tetranolactonyl dienyl esters with different amines resulted in the respective 5-hydroxy lactams. Subsequent dehydration of the hydroxy lactams with p-toluene sulphonic acid afforded the dienyl tetramic acid derivatives. All reactions were performed at ambient temperature and the yields are good. Conclusion An efficient and practical method for the synthesis of dienyl tetramic acid derivatives from inexpensive and easily accessible ascorbic acid has been developed. The compounds bear structural similarities to the tetramic acid based polyenic antibiotics and thus this method offers a new and short route for the synthesis of tetramic acid derivatives of biological significance.

Bisht Surendra S

2006-12-01

127

A selective 3-acylation of tetramic acids and the first synthesis of ravenic acid.  

Science.gov (United States)

3-Acyltetramic acids, including delicate 3-oligoenoyl derivatives, such as the Penicillium metabolite ravenic acid, were prepared in two high-yielding steps. Reaction of tetramic acids with the ylide Ph(3)PCCO afforded exclusively the corresponding 3-acylylidenetetramic acids. These were amenable to Wittig olefinations with aliphatic, aromatic, saturated and unsaturated aldehydes after deprotonation with KOtBu. Due to its simplicity, selectivity and tolerance of pH-sensitive groups this method is superior to the established acylation protocols by Jones and Yoshii. It is also applicable to the synthesis of 3-acyltetronic acids. The new 3-oligoenoyl tetramic acids exhibited structure-dependent antimicrobial and cytotoxic activity. PMID:20066698

Schlenk, Andrea; Diestel, Randi; Sasse, Florenz; Schobert, Rainer

2010-02-22

128

Biotin Synthesis Begins by Hijacking the Fatty Acid Synthetic Pathway  

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Although biotin is an essential enzyme cofactor found in all three domains of life, our knowledge of its biosynthesis remains fragmentary. Most of the carbon atoms of biotin are derived from pimelic acid, a seven carbon dicarboxylic acid, but the mechanism whereby Escherichia coli assembles this intermediate remains unknown. Genetic analysis identified only two genes of unknown function required for pimelate synthesis, bioC and bioH. We report in vivo and in vitro evidence that the pimeloyl m...

Lin, Steven; Hanson, Ryan E.; Cronan, John E.

2010-01-01

129

Synthesis of new C?-tetrasubstituted ?-amino acids  

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C?-Tetrasubstituted ?-amino acids are important building blocks for the synthesis of peptidemimetics with stabilized secondary structure, because of their ability to rigidify the peptide backbone. Recently our group reported a new class of cyclic C?-tetrasubstituted tetrahydrofuran ?-amino acids prepared from methionine and aromatic aldehydes. We now report the extension of this methodology to aliphatic aldehydes. Although such aldehydes are prone to ...

Grauer, Andreas A.; Nig, Burkhard K.

2009-01-01

130

Methane-to-acetic acid synthesis matriculates at Penn State  

Energy Technology Data Exchange (ETDEWEB)

Direct conversion of methane to commercially valuable chemicals remains one of the grails of industrial chemistry. But scientists at Pennsylvania State University (University Park) appear to have made a significant step forward, reporting the direct catalytic conversion of methane into acetic acid under relatively mild conditions. Commercial acetic production involves a three-step process, including steam reforming of methane to synthesis gas (syngas) and the carbonylation of methanol of acetic acid.

Rotman, D.

1994-04-20

131

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

132

Synthesis of [14CO]ellagic acid  

International Nuclear Information System (INIS)

[14CO]Ellagic acid with a chemical purity of 98.9% and radiochemical purity of 99.9% was synthesized with an overall yield of 16% (both chemically and radiochemically). Reaction of 14CO2 with lithiated 3,4,5-trimethoxybenzene and demethylation of the resulting 3,4,5-trimethoxybenzoic acid was followed by esterification and coupling of methyl gallate into ellagic acid. Two efficient coupling methods were employed: direct aeration and aeration of methyl gallate in the presence of the phenolic oxidase, tyrosinase. The latter method produced the highest yield and purity. This preparation produced [14CO]ellagic acid with a specific activity of 20 mCi/mmol. The yields of labeled 3,4,5-trimethoxybenzoic acid and ellagic acid based on Ba14CO3 were 65% and 16%, respectively. (author)

1991-01-01

133

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

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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

134

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

135

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

2003-06-01

136

Health consequences of catabolic synthesis of hippuric acid in humans.  

Science.gov (United States)

Hippuric acid has been a major human metabolite for years. However, there is no well-known documented health benefit associated with it except for excretion of environmental-toxic exposures of aromatic compounds such as toluene, or from dietary protein degradation and re-synthesis by intestinal microflora metabolism of quinic acid via the shikimate pathway. Thus hippuric acid can appear in humans as an excretory product from natural or unnatural sources. It has been believed over the years that the major source of urinary hippuric acid levels in humans has come from environmental toxic solvent exposures. However, more recently it was been shown that approximately 1-2 mM hippuric acid is excreted daily in the urine, even in the absence of organic solvent exposure, signalling abundant metabolic dietary sources of hippuric acid are also apparent. One of these has been dietary proteins. The other is from the well-documented presence of quinic acid in healthy colored foodstuffs. Quinic acid is a key metabolite associated with the shikimate pathway existing only in plants, and it is responsible for essential amino acid biosynthesis such as tryptophan, phenylalanine and tyrosine. Here we review the evidence that the human gastrointestinal tract microflora are responsible for quinic acid metabolism not only to hippuric acid, but more importantly to efficacious antioxidant amino acids and vitamins. PMID:19891605

Pero, Ronald W

2010-02-01

137

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

138

Synthesis and chirality of amino acids under interstellar conditions.  

Science.gov (United States)

Amino acids are the fundamental building blocks of proteins, the biomolecules that provide cellular structure and function in all living organisms. A majority of amino acids utilized within living systems possess pre-specified orientation geometry (chirality); however the original source for this specific orientation remains uncertain. In order to trace the chemical evolution of life, an appreciation of the synthetic and evolutional origins of the first chiral amino acids must first be gained. Given that the amino acids in our universe are likely to have been synthesized in molecular clouds in interstellar space, it is necessary to understand where and how the first synthesis might have occurred. The asymmetry of the original amino acid synthesis was probably the result of exposure to chiral photons in the form of circularly polarized light (CPL), which has been detected in interstellar molecular clouds. This chirality transfer event, from photons to amino acids, has been successfully recreated experimentally and is likely a combination of both asymmetric synthesis and enantioselective photolysis. A series of innovative studies have reported successful simulation of these environments and afforded production of chiral amino acids under realistic circumstellar and interstellar conditions: irradiation of interstellar ice analogues (CO, CO2, NH3, CH3OH, and H2O) with circularly polarized ultraviolet photons at low temperatures does result in enantiomer enriched amino acid structures (up to 1.3% ee). This topical review summarizes current knowledge and recent discoveries about the simulated interstellar environments within which amino acids were probably formed. A synopsis of the COSAC experiment onboard the ESA cometary mission ROSETTA concludes this review: the ROSETTA mission will soft-land on the nucleus of the comet 67P/Churyumov-Gerasimenko in November 2014, anticipating the first in situ detection of asymmetric organic molecules in cometary ices. PMID:22976459

Giri, Chaitanya; Goesmann, Fred; Meinert, Cornelia; Evans, Amanda C; Meierhenrich, Uwe J

2013-01-01

139

Synthesis of new C?-tetrasubstituted ?-amino acids  

Directory of Open Access Journals (Sweden)

Full Text Available C?-Tetrasubstituted ?-amino acids are important building blocks for the synthesis of peptidemimetics with stabilized secondary structure, because of their ability to rigidify the peptide backbone. Recently our group reported a new class of cyclic C?-tetrasubstituted tetrahydrofuran ?-amino acids prepared from methionine and aromatic aldehydes. We now report the extension of this methodology to aliphatic aldehydes. Although such aldehydes are prone to give aldol products under the reaction conditions used, we were able to obtain the target cyclic amino acids in low to moderate yields and in some cases with good diastereoselectivity.

Andreas A. Grauer

2009-02-01

140

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,

 
 
 
 
141

Oxetane &-amido acids : synthesis and derivatisation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In the present work the potential of oxetane ?-amino acids as scaffolds was evaluated. While there is an ample precedence for the use of 6- and 5-membered carbohydrate-derived amino acids as scaffolds, there are no reports on oxetanebased libraries. The oxetane ring is an interesting source of rigidity and well-defined exit vectors, and this unit is present in some important naturally occurring bioactive molecules, such as taxol, oxetanocin or oxetin. Nevertheless, the intrinsic chemical and...

Lucas, Susana Dias

2009-01-01

142

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

143

Regulation of protein synthesis by amino acids in muscle of neonates  

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The marked increase in skeletal muscle mass during the neonatal period is largely due to a high rate of postprandial protein synthesis that is modulated by an enhanced sensitivity to insulin and amino acids. The amino acid signaling pathway leading to the stimulation of protein synthesis has not been fully elucidated. Among the amino acids, leucine is considered to be a principal anabolic agent that regulates protein synthesis. mTORC1, which controls protein synthesis, has been implicated as ...

Suryawan, Agus; Davis, Teresa A.

2011-01-01

144

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

1995-01-01

145

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

146

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

147

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

148

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

149

Synthesis of novel adamantyl and homoadamantyl-substituted ?-hydroxybutyric acids.  

Science.gov (United States)

Several new adamantyl and homoadamantyl-substituted [Formula: see text]-hydroxybutyric acids, 2-[2-(1-adamantyl)ethyl]-3-hydroxybutyric acid (2), 2-(3-homoadamantyl)-3-hydroxybutyric acid (3), and 2-(1-homoadamantyl)-3-hydroxybutyric acid (4), analogues of the 2-(1-adamantyl)-3-hydroxybutyric acid (1), have been prepared as mixtures of diastereoisomers using selective reduction of corresponding [Formula: see text]-keto esters or aldol condensation of the corresponding carboxylic acid and acetaldehyde. The rearrangement of adamantylmethyl and 3-homoadamantyl groups provided entry to both 3-homoadamantyl and 1-homoadamantyl-substituted hydroxy acids 3 and 4, respectively. The relative configurations of diastereoisomers 3 and 4 have been determined by NMR spectroscopy comparing the values of coupling constants. Adamantyl-substituted [Formula: see text]-hydroxybutyric acid 2 has also been prepared in enantiomerically pure form by Evan's asymmetric synthesis and the absolute configuration has been determined by X-ray crystallography. Contrary to the long-chain acid 2, the attempt to prepare short-chain hydroxy acids 1 and 4 by the same method failed indicating pronounced sensitivity of the used method to the vicinity of the bulky cage group. PMID:24043584

Matkovi?, Marija; Vukeli?, Stella; Cirimoti?, Ružica; Kragol, Goran; Mol?anov, Krešimir; Mlinari?-Majerski, Kata

2013-11-01

150

Inhibition of polyketide synthesis in Alternaria alternata by the fatty acid synthesis inhibitor cerulenin.  

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The fatty acid synthase inhibitor cerulenin (50 to 100 micrograms/ml) inhibited production of the polyketide mycotoxins alternariol (AOH) and alternariol monomethyl ether (AME) by the mold Alternaria alternata. The results suggested that AOH synthesis was inhibited by a direct mechanism by cerulenin, whereas production of AME was probably limited by a shortage of the precursor AOH.

1992-01-01

151

Fatty acid phytyl ester synthesis in chloroplasts of Arabidopsis.  

Science.gov (United States)

During stress or senescence, thylakoid membranes in chloroplasts are disintegrated, and chlorophyll and galactolipid are broken down, resulting in the accumulation of toxic intermediates, i.e., tetrapyrroles, free phytol, and free fatty acids. Chlorophyll degradation has been studied in detail, but the catabolic pathways for phytol and fatty acids remain unclear. A large proportion of phytol and fatty acids is converted into fatty acid phytyl esters and triacylglycerol during stress or senescence in chloroplasts. We isolated two genes (PHYTYL ESTER SYNTHASE1 [PES1] and PES2) of the esterase/lipase/thioesterase family of acyltransferases from Arabidopsis thaliana that are involved in fatty acid phytyl ester synthesis in chloroplasts. The two proteins are highly expressed during senescence and nitrogen deprivation. Heterologous expression in yeast revealed that PES1 and PES2 have phytyl ester synthesis and diacylglycerol acyltransferase activities. The enzymes show broad substrate specificities and can employ acyl-CoAs, acyl carrier proteins, and galactolipids as acyl donors. Double mutant plants (pes1 pes2) grow normally but show reduced phytyl ester and triacylglycerol accumulation. These results demonstrate that PES1 and PES2 are involved in the deposition of free phytol and free fatty acids in the form of phytyl esters in chloroplasts, a process involved in maintaining the integrity of the photosynthetic membrane during abiotic stress and senescence. PMID:22623494

Lippold, Felix; vom Dorp, Katharina; Abraham, Marion; Hölzl, Georg; Wewer, Vera; Yilmaz, Jenny Lindberg; Lager, Ida; Montandon, Cyrille; Besagni, Céline; Kessler, Felix; Stymne, Sten; Dörmann, Peter

2012-05-01

152

Fatty acid synthesis is a therapeutic target in human liposarcoma.  

Science.gov (United States)

Liposarcomas (LS) are mesenchymal tumors that can recur after surgical resection and often do not respond to presently available medical therapies. This study demonstrates the dependence of LS on de novo long-chain fatty acid synthesis for growth. Lipogenesis can be impaired by inhibiting the activities of lipogenic enzymes, including acetyl CoA-carboxylase (ACC) and fatty acid synthase (FASN), or by suppressing the expression of key genes involved in the pathway and its regulation. The FASN inhibitors cerulenin and orlistat reduced the growth of two LS cell lines (LiSa2, SW872), as did inhibition of ACC with soraphen A. CDDO-Me, a synthetic triterpenoid, suppressed expression of Spot 14 and FASN genes and likewise inhibited LS cell growth. Importantly, the anti-proliferative effect of each agent was prevented by the co-administration of palmitate, the major product of cellular long-chain fatty acid synthesis. In stark contrast to LS cells, these compounds had no effect on the growth of fibroblasts. Four biochemically distinct agents that target critical points in the fatty acid synthetic pathway exert anti-proliferative effects on LS cells, and rescue of cell growth by palmitic acid suggests that reduced tumor cell lipogenesis mediates the growth inhibition. These findings warrant further studies aimed at the clinical exploitation of the dependence of LS cell growth on fatty acids. PMID:20372807

Olsen, Arne M; Eisenberg, Burton L; Kuemmerle, Nancy B; Flanagan, Alison J; Morganelli, Peter M; Lombardo, Portia S; Swinnen, Johannes V; Kinlaw, William B

2010-05-01

153

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.

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

154

Identification and Isolation of Anaerobic, Syntrophic Phthalate Isomer-Degrading Microbes from Methanogenic Sludges Treating Wastewater from Terephthalate Manufacturing  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The microbial populations responsible for anaerobic degradation of phthalate isomers were investigated by enrichment and isolation of those microbes from anaerobic sludge treating wastewater from the manufacturing of terephthalic acid. Primary enrichments were made with each of three phthalate isomers (ortho-, iso-, and terephthalate) as the sole energy source at 37°C with two sources of anaerobic sludge (both had been used to treat wastewater containing high concentrations of phthalate isom...

2004-01-01

155

Synthesis of nervonic acid 14C-24  

International Nuclear Information System (INIS)

Methyl iodide-14C was condensed with 2-(1-lithio-hept-1-yn-6-yl) 1,3-dioxolanne in presence of HMPT and benzene to give 2-(oct-2-yn-8-yl-1-14C) 1,3-dioxolanne. Catalytic reduction, followed by acid hydrolysis led to pelargonic aldehyde 9-14C. Condensation of this aldehyde with an excess of ?-carbomethoxy-tetradecylidene, triphenyl phosphorane produced methyl nervonate 24-14C. The latter was isolated from its trans isomer by chromatography on a silver nitrate impregnated silicagel column. Finally, nervonic acid 24-14C was obtained by alkaline hydrolysis (specific activity : 52 mCi/mMole) with an overall yield of 7% based on methyl iodide-14C. (author)

1981-01-01

156

Synthesis of azido derivatives of mucobromic acid  

Directory of Open Access Journals (Sweden)

Full Text Available Mucobromic acid is a highly reactive multicentered molecule. It was converted to its corresponding but unstable diazido derivative by reaction with two equivalents of sodium azide. The resultant 3,4-diazido-5-hydroxyfuran-2(5H-one was obtained in moderate yield (42% but decomposed readily even at low temperatures. Its more stable analogue 3,4-diazido-5-methoxyfuran-2(5H-one was obtained in excellent yield after reacting 5-methoxy-3,4-dibromofuranone with two equivalents of sodium azide. The 4,5-dibromopyridazinones which are in effect masked mucobromic acid derivatives, underwent nucleophilic substitution reactions with various nucleophiles, including azides and afforded corresponding azidopyridazinones in good yields. The synthesized azido-furanone and pyridazinone derivatives are earmarked for click reactions.DOI: http://dx.doi.org/10.4314/bcse.v27i1.17

N. Mbebe

2013-04-01

157

Phosphatidic acid synthesis in castor bean endosperm  

Energy Technology Data Exchange (ETDEWEB)

Enzyme assays on organelles isolated from the endosperm of castor bean (Ricinus communis var. Hale) by sucrose density gradient centrifugation showed that palmitoyl-CoA:sn-glycerol 3-phosphate acyltransferase (EC 2.3.1.15) was localized in the membranes of the endoplasmic reticulum. Mn/sup 2 +/ was required for activity, but Ca/sup 2 +/ and Mg/sup 2 +/ could substitute for Mn/sup 2 +/ at higher concentrations. The apparent Km was 170 ..mu..M for sn-glycerol 3-phosphate and approximately 8 ..mu..M for palmitoyl-CoA. The optimum pH range was 7 to 7.5 and the principal reaction product was diacyl-sn-glycerol 3-phosphate (phosphatidic acid). Monoacyl-sn-glycerol 3-phosphate (lysophosphatidic acid) was not released as a free intermediate in the reaction. The maximum activity of the enzyme occurred immediately after imbibition, preceding the development of mitochondria and glyoxysomes.

Vick, B.; Beevers, H.

1977-03-01

158

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 1

1987-05-01

159

Oligoglyceric acid synthesis by autocondensation of glyceroyl thioester  

Science.gov (United States)

The autocondensation of the glyceroyl thioester, S-glyceroyl-ethane-thiol, yielded olioglyceric acid. The rates of autocondensation and hydrolysis of the thioester increased from pH 6.5 to pH 7.5 in 2,6-lutidine and imidazole buffers. Autocondensation and hydrolysis were much more rapid in imidazole buffers as compared to 2,6-lutidine and phosphate buffers. The efficiency of ester bond synthesis was about 20 percent for 40 mM S-glyceroyl-ethane-thiol in 2,6-lutidine and imidazole buffers near neutral pH. The size and yield of the olioglyceric acid products increased when the concentration of the thioester was increased. The relationship of these results to prebiotic polymer synthesis is discussed.

Weber, Arthur L.

1987-01-01

160

SYNTHESIS AND ANTIBACTERIAL ACTIVITY OF AMIDE DERIVATIVES FROM ACRYLOPIMARIC ACID  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper reports on the synthesis of a series of amide derivatives from acrylopimaric acid (APA). The derivatives contained aromatic groups and were characterized by IR, 1HNMR, MS, and elemental analysis. The antibacterial activity of the derivatives against Gram-negative bacteria and Gram-positive bacteria were also investigated. When compared with the other derivatives, compounds 3a and 3f showed much higher activity against Escherichia coli (Gram-negative bacteria) with inhibition zones ...

2012-01-01

 
 
 
 
161

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

162

Cancer chemotherapy: targeting folic acid synthesis  

Directory of Open Access Journals (Sweden)

Full Text Available Nicole Hagner, Markus JoergerDepartment of Medical Oncology, Cantonal Hospital, St Gallen, SwitzerlandAbstract: Antifolates are structural analogs of folates, essential one-carbon donors in the synthesis of DNA in mammalian cells. Antifolates are inhibitors of key enzymes in folate metabolism, namely dihydrofolate reductase, ?-glycinamide ribonucleotide transformylase, 5'-amino-4'-imidazolecarboxamide ribonucleotide transformylase, and thymidylate synthetase. Methotrexate is one of the earliest anticancer drugs and is extensively used in lymphoma, acute lymphoblastic leukemia, and osteosarcoma, among others. Pemetrexed has been approved in combination with cisplatin as first-line treatment for advanced non-squamous-cell lung cancer, as a single agent for relapsed non-small-cell lung cancer after platinum-containing chemotherapy, and in combination with cisplatin for the treatment of pleural mesothelioma. Raltitrexed is approved in many countries (except in the United States for advanced colorectal cancer, but its utilization is mainly limited to patients intolerant to 5-fluorouracil. Pralatrexate has recently been approved in the United States for relapsed or refractory peripheral T-cell lymphoma. This article gives an overview of the cellular mechanism, pharmacology, and clinical use of classical and newer antifolates and discusses some of the main resistance mechanisms to antifolate drugs.Keywords: antifolates, cancer, molecular pharmacology, pemetrexed, methotrexate, folate metabolism

Nicole Hagner

2010-11-01

163

Cancer chemotherapy: targeting folic acid synthesis.  

Science.gov (United States)

Antifolates are structural analogs of folates, essential one-carbon donors in the synthesis of DNA in mammalian cells. Antifolates are inhibitors of key enzymes in folate metabolism, namely dihydrofolate reductase, ?-glycinamide ribonucleotide transformylase, 5'-amino-4'-imidazolecarboxamide ribonucleotide transformylase, and thymidylate synthetase. Methotrexate is one of the earliest anticancer drugs and is extensively used in lymphoma, acute lymphoblastic leukemia, and osteosarcoma, among others. Pemetrexed has been approved in combination with cisplatin as first-line treatment for advanced non-squamous-cell lung cancer, as a single agent for relapsed non-small-cell lung cancer after platinum-containing chemotherapy, and in combination with cisplatin for the treatment of pleural mesothelioma. Raltitrexed is approved in many countries (except in the United States) for advanced colorectal cancer, but its utilization is mainly limited to patients intolerant to 5-fluorouracil. Pralatrexate has recently been approved in the United States for relapsed or refractory peripheral T-cell lymphoma. This article gives an overview of the cellular mechanism, pharmacology, and clinical use of classical and newer antifolates and discusses some of the main resistance mechanisms to antifolate drugs. PMID:21301589

Hagner, Nicole; Joerger, Markus

2010-01-01

164

Cyclic diguanylic acid and cellulose synthesis in Agrobacterium tumefaciens.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The occurrence of the novel regulatory nucleotide bis(3',5')-cyclic diguanylic acid (c-di-GMP) and its relation to cellulose biogenesis in the plant pathogen Agrobacterium tumefaciens was studied. c-di-GMP was detected in acid extracts of 32P-labeled cells grown in various media, and an enzyme responsible for its formation from GTP was found to be present in cell-free preparations. Cellulose synthesis in vivo was quantitatively assessed with [14C]glucose as a tracer. The organism produced cel...

Amikam, D.; Benziman, M.

1989-01-01

165

Synthesis of Rosin Acid Starch Catalyzed by Lipase  

Science.gov (United States)

Rosin, an abundant raw material from pine trees, was used as a starting material directly for the synthesis of rosin acid starch. The esterification reaction was catalyzed by lipase (Novozym 435) under mild conditions. Based on single factor experimentation, the optimal esterification conditions were obtained as follows: rosin acid/anhydrous glucose unit in the molar ratio 2?:?1, reaction time 4?h at 45°C, and 15% of lipase dosage. The degree of substitution (DS) reaches 0.098. Product from esterification of cassava starch with rosin acid was confirmed by FTIR spectroscopy and iodine coloration analysis. Scanning electron microscopy and X-ray diffraction analysis showed that the morphology and crystallinity of the cassava starch were largely destroyed. Thermogravimetric analysis indicated that thermal stability of rosin acid starch decreased compared with native starch.

Lin, Rihui; Li, He; Long, Han; Su, Jiating; Huang, Wenqin

2014-01-01

166

Facile Synthesis of Oleanolic Acid Monoglycosides and Diglycosides  

Directory of Open Access Journals (Sweden)

Full Text Available Oleanolic acid and its glycosides are important natural products, possessing various attractive biological activities such as antitumor, antivirus and anti-inflammatory properties. In the present work, fifteen oleanolic acid saponins bearing various saccharide moieties, including 3-monoglycoside, 28-monoglycoside and 3,28-diglycoside, were easily synthesized in high yields. Benzyl was chosen as the protective group for the COOH(28 group, instead of commonly used methyl and allyl, to avoid difficulties in the final deprotection. Alkali-promoted condensation of the carboxylic acid with bromoglycosides was found to be more efficient in the synthesis of 28-glycosides. Two approaches were investigated and proved practicable in the preparation of 3,28- diglycosides. This method is suitable for preparing oleanolic acid glycosides with structural diversity for extensive biological evaluation and structure-activity relationship study, and it also apply new idea for the corresponding synthetic methods to the glycoside derivatives of other triterpenoid.

Mao-Sheng Cheng

2008-07-01

167

Synthesis of rosin Acid starch catalyzed by lipase.  

Science.gov (United States)

Rosin, an abundant raw material from pine trees, was used as a starting material directly for the synthesis of rosin acid starch. The esterification reaction was catalyzed by lipase (Novozym 435) under mild conditions. Based on single factor experimentation, the optimal esterification conditions were obtained as follows: rosin acid/anhydrous glucose unit in the molar ratio 2?:?1, reaction time 4?h at 45°C, and 15% of lipase dosage. The degree of substitution (DS) reaches 0.098. Product from esterification of cassava starch with rosin acid was confirmed by FTIR spectroscopy and iodine coloration analysis. Scanning electron microscopy and X-ray diffraction analysis showed that the morphology and crystallinity of the cassava starch were largely destroyed. Thermogravimetric analysis indicated that thermal stability of rosin acid starch decreased compared with native starch. PMID:24977156

Lin, Rihui; Li, He; Long, Han; Su, Jiating; Huang, Wenqin

2014-01-01

168

Design and Synthesis of a Dual Linker for Solid Phase Synthesis of Oleanolic Acid Derivatives  

Directory of Open Access Journals (Sweden)

Full Text Available A hydrophilic amino-terminated poly(ethylene glycol-type dual linker for solid phase synthesis of oleanolic acid derivatives using trityl chloride resin was designed and synthesized for the first time. Model reactions in both liquid and solid phase were performed to show the feasibility of its selective cleavage at two different sites. The biological assay results indicated that the long and flexible alkyl ether functionality in the linker is less likely to be critical for the binding event. Following the successful solid-phase synthesis of model compounds, the potential of this dual linker in reaction monitoring and target identification is deemed worthy of further study.

Shaorong Wang

2011-06-01

169

Induction of phytic acid synthesis by abscisic acid in suspension-cultured cells of rice.  

Science.gov (United States)

A pathway of phytic acid (PA) synthesis in plants has been revealed via investigations of low phytic acid mutants. However, the regulation of this pathway is not well understood because it is difficult to control the environments of cells in the seeds, where PA is mainly synthesized. We modified a rice suspension culture system in order to study the regulation of PA synthesis. Rice cells cultured with abscisic acid (ABA) accumulate PA at higher levels than cells cultured without ABA, and PA accumulation levels increase with ABA concentration. On the other hand, higher concentrations of sucrose or inorganic phosphorus do not affect PA accumulation. Mutations in the genes RINO1, OsMIK, OsIPK1 and OsLPA1 have each been reported to confer low phytic acid phenotypes in seeds. Each of these genes is upregulated in cells cultured with ABA. OsITPK4 and OsITPK6 are upregulated in cells cultured with ABA and in developing seeds. These results suggest that the regulation of PA synthesis is similar between developing seeds and cells in this suspension culture system. This system will be a powerful tool for elucidating the regulation of PA synthesis. PMID:24467907

Matsuno, Koya; Fujimura, Tatsuhito

2014-03-01

170

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

1983-01-01

171

Biphasic effect of oleic acid on hepatic cholesterol synthesis  

Energy Technology Data Exchange (ETDEWEB)

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 {sup 3}H from {sup 3}H{sub 2}O (23 mCi) into C was lower in the presence of OA (3,295{plus minus}277 dpm/g) than in its absence (4,969{plus minus}471 dpm/g), while over the 4 hour interval incorporation was elevated by OA (17,088{plus minus}2,527 vs 10,278{plus minus}1,288 dpm/g). Incorporation of {sup 3}H 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{plus minus}24 vs 112{plus minus}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{plus minus}13 pmol/minute/mg after 4 hours), while in the presence of OA, HMGR activity was sustained (126{plus minus}25 pmol/minute/mg). Total HMGR activity (measured in the absence of NaF) paralleled this change.

Fungwe, T.V.; Cagen, L.M.; Wilcox, H.G.; Heimberg, M. (Univ. of Tennessee, Memphis (United States))

1990-02-26

172

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 sustained (126±25 pmol/minute/mg). Total HMGR activity (measured in the absence of NaF) paralleled this change

1990-02-26

173

Synthesis and crystal structure of maleopimaric acid.  

Science.gov (United States)

The title compound maleopimaric acid was synthesized by a Diels-Alder reaction between maleic anhydride and Pinus elliottii engelm oleoresin at room temperature and it was characterized by single crystal X-ray diffraction. The white crystals crystallized in the orthorhombic system, space group P2(12121) with cell dimensions: a = 7.6960 (15) A, b = 11.851 (2) A, c = 24.577 (5) A, alpha = 90 degrees, beta = 90 degrees, gamma = 90 degrees, V = 2241.6(8) A(3), and R(1) = 0.0716, wR(2) = 0.1975. The two fused and unbridged cyclohexane rings form a trans ring junction with chair conformation with two methyl groups in axis positions, the anhydride ring is planar. Crystal water existed in the molecular and stabilized the structure through intermolecular hydrogen bonds. PMID:18626819

Rao, Xiaoping; Song, Zhanqian; Yao, Xujie; Han, Chunrui; Shang, Shibin

2008-01-01

174

Waste product profile: Polyethylene terephthalate  

Energy Technology Data Exchange (ETDEWEB)

Polyethylene terephthalate (PET) is a plastic resin used primarily to make bottles. Soft drinks are the primary product packaged in PET. Salad dressing, peanut butter, and other household and consumer products also use PET bottles. PET is also used for film, sheeting for cups and food trays, ovenable trays, and other uses. PET is a relatively new packaging resin, first commercialized in the early `70s. Because it is an ``engineered`` resin, it is more expensive than commodity resins such as high-density polyethylene (HDPE). The primary market for recycled PET is the fiber industry, which uses PET for carpet fiber, sweaters and other clothing, and for other uses. Recycled PET can also be used for food and beverage containers. Export markets, particularly Asian countries, are becoming increasingly important.

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

1996-02-01

175

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 (λ= 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

176

Enantioselective synthesis of H-phosphinic acids bearing natural amino acid residues.  

Science.gov (United States)

The first systematic study on the asymmetric synthesis of H-phosphinic acids bearing natural protein amino acid residues was reported on the basis of the asymmetric addition of ethyl diethoxymethylphosphinate to N-tert-butanesulfinyl imines. Good yields and moderate to high enantioselectivities were obtained. Reliable methods were developed for the elucidation of the stereochemistry of these phosphinic acids and derivatives thereof. The transformation of the side chains of these analogues was studied. Methods for the conversion of the ?-aminophosphinates to oligopetides were reported. PMID:23772951

Yao, Qiuli; Yuan, Chengye

2013-07-19

177

Lipase-catalyzed synthesis of fattythioic acids from palm oil.  

Science.gov (United States)

The present work focuses on the synthesis of fattythioic acids (FTAs) by a one-step lipase catalyzed reaction of palm oil with carbonothioic S,S-acid using Lipozyme. The product was characterized using Fourier transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance ((1)H NMR) technique and elemental analysis. The effects of various reaction parameters such as reaction time, temperature, amount of enzyme, molar ratio of substrates, and various organic solvents of the reaction system were investigated. The optimum conditions to produce FTAs were respectively, incubation time, 20 h, temperature, 40°C, amount of enzyme, 0.05 g and molar ratio of carbonothioic S,S-acid to palm oil, 5.0:1.0. Hexane was the best solvent for this reaction. The conversion of the products at optimum conditions was around 91%. PMID:21178316

Al-Mulla, Emad A Jaffar

2011-01-01

178

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

179

Bioorganic Synthesis; Monosodium Glutamate and Other Amino Acids  

Science.gov (United States)

The March featured molecules are discussed in the article "The Monosodium Glutamate Story: The Commercial Production of MSG and Other Amino Acids". This paper provides a number of opportunities for introducing students to the importance of stereochemistry in bioorganic synthesis. The collection here includes all of the relevant molecules in the synthesis of ?-amino-?-aminocaprolactam (ACL). The introduction of two chiral centers in the reaction of cyclohexene with NOCl results in four diastereomers, and it is instructive to ask students to predict the relative abundance of those isomers and the dependence of that distribution on the extent to which the reaction is syn- or anti-addition, and to account for the fact that the resultant oxime, and the ACL, are obtained as racemates.

180

Design and Synthesis of a Dual Linker for Solid Phase Synthesis of Oleanolic Acid Derivatives  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A hydrophilic amino-terminated poly(ethylene glycol)-type dual linker for solid phase synthesis of oleanolic acid derivatives using trityl chloride resin was designed and synthesized for the first time. Model reactions in both liquid and solid phase were performed to show the feasibility of its selective cleavage at two different sites. The biological assay results indicated that the long and flexible alkyl ether functionality in the linker is less likely to be critical for the binding event....

2011-01-01

 
 
 
 
181

Recovery of monomers from polyethylene terephthalate by hydrolysis under pressure; Koon koatsusui ni yoru PET no kasui bunkai monomer ka  

Energy Technology Data Exchange (ETDEWEB)

For the purpose of recycling of polyethylene terephthalate (PET), experiments of hydrolysis at high temperature under high pressure were conducted to recover monomers. For the experiments, the PET and water were charged in the reactor after the displacement by Ar gas. Results obtained are as follows. The effect of pressure can be almost neglected. When PET was hydrolyzed at temperature below its melting point of 245 centigrade, the PET pellets remained unreacted. At 250 centigrade, the pellets did not remain and the liquid/liquid reaction proceeded to recover the terephthalic acid with a rate of more than 80%. The non-reacted PET oligomers remained. At 300 centigrade, more than 90% of terephthalic acid was recovered. Another 10% contained oligomers and by-products. Above 300 centigrade, the recovery rate decreased due to the conversion of terephthalic acid into benzoic acid through the decarboxylation reaction. The maximum recovery rate of ethylene glycol existed between 250 and 300 centigrade, and at higher temperatures, it converted into acetaldehyde. No catalyst was required. Under the optimum condition, 90% of terephthalic acid and 70% of ethylene glycol were recovered. 6 refs., 9 figs., 1 tab.

Yamamoto, S.; Aoki, M.; Yamagata, M. [Kobe Steel, Ltd., Kobe (Japan)

1996-05-01

182

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

1995-01-01

183

An improved synthesis of [15N] 16-Doxyl stearic acid  

International Nuclear Information System (INIS)

An improved method for the synthesis of [15N] 16-Doxyl stearate, a fatty-acid spin label, is reported. The method requires only one mole of [15N] 2-amino-2-methyl propanol per mole of methyl keto stearate with an overall yield of about 50%. In contrast, the previous method produced only 1-3% yield. The great improvement in yield was achieved mainly through the reduction of reaction volume which increases the reaction rate by the law of mass action. (author)

1987-01-01

184

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

185

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 PdCl(4) (-2). PMID:22068901

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

2009-04-01

186

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

187

Solid-phase synthesis of peptide nucleic acids.  

Science.gov (United States)

Peptide nucleic acids (PNA) were synthesized by a modified Merrifield method using several improvements. Activation by O-[benzotriazol-1-yl]-1,1,3,3-tetramethyluronium hexafluorophosphate in combination with in situ neutralization of the resin allowed efficient coupling of all four Boc-protected PNA monomers within 30 min. HPLC analysis of the crude product obtained from a fully automated synthesis of the model PNA oligomer H-CGGACTAAGTCCATTGC-Gly-NH2, indicated an average yield per synthetic cycle of 97.1%. N1-benzyloxycarbonyl-N6(3)-methylimidazole triflate substantially outperformed acetic anhydride as a capping reagent. The resin-bound PNAs were successfully cleaved by the 'low-high' trifluoromethanesulphonic acid procedure. PMID:9222994

Christensen, L; Fitzpatrick, R; Gildea, B; Petersen, K H; Hansen, H F; Koch, T; Egholm, M; Buchardt, O; Nielsen, P E; Coull, J; Berg, R H

1995-01-01

188

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

189

Cyclic diguanylic acid and cellulose synthesis in Agrobacterium tumefaciens  

International Nuclear Information System (INIS)

The occurrence of the novel regulatory nucleotide bis(3',5')-cyclic diguanylic acid (c-di-GMP) and its relation to cellulose biogenesis in the plant pathogen Agrobacterium tumefaciens was studied. c-di-GMP was detected in acid extracts of 32P-labeled cells grown in various media, and an enzyme responsible for its formation from GTP was found to be present in cell-free preparations. Cellulose synthesis in vivo was quantitatively assessed with [14C]glucose as a tracer. The organism produced cellulose during growth in the absence of plant cells, and this capacity was retained in resting cells. Synthesis of a cellulosic product from UDP-glucose in vitro with membrane preparations was markedly stimulated by c-di-GMP and its precursor GTP and was further enhanced by Ca2+. The calcium effect was attributed to inhibition of a c-di-GMP-degrading enzyme shown to be present in the cellulose synthase-containing membranes

1989-01-01

190

recA gene product is responsible for inhibition of deoxyribonucleic acid synthesis after ultraviolet irradiation  

International Nuclear Information System (INIS)

Deoxyribonucleic acid synthesis after ultraviolet irradiation was studied in wild-type, uvrA, recB, recA, recB, and recA Escherichia coli strains. Inhibition of deoxyribonucleic acid synthesis, which occurs almost immediately after exposing the cells to ultraviolet radiation, depends on the functional gene recA

1980-01-01

191

Induction of fatty acid synthesis by pravastatin sodium in rat liver and primary hepatocytes.  

Science.gov (United States)

We examined the effect of pravastatin sodium (pravastatin), a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, on fatty acid synthesis in rat liver. The repeated administration of pravastatin to rats at 250 mg/kg for 7 days led to a 2.8-fold increase in fatty acid synthesis in the liver. The diurnal change of fatty acid synthesis was not affected by the treatment. Hepatic fatty acid synthase activity was increased 3.2-fold, while acetyl-CoA carboxylase activity was not changed by the repeated administration of pravastatin. In rat hepatocytes, the incubation with 2 microg/ml pravastatin for 24 h increased fatty acid synthase activity 1.5-fold, as well as HMG-CoA reductase activity 2.8-fold. These results suggest that HMG-CoA reductase inhibitors might increase fatty acid synthesis in vivo through the induction of hepatic fatty acid synthase. PMID:9218706

Fujioka, T; Tsujita, Y; Shimotsu, H

1997-06-11

192

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

193

Synthesis of acid addition salt of delta-aminolevulinic acid from 5-bromo levulinic acid esters  

Energy Technology Data Exchange (ETDEWEB)

A process of preparing an acid addition salt of delta-aminolevulinc acid comprising: a) dissolving a lower alkyl 5-bromolevulinate and hexamethylenetetramine in a solvent selected from the group consisting of water, ethyl acetate, chloroform, acetone, ethanol, tetrahydrofuran and acetonitrile, to form a quaternary ammonium salt of the lower alkyl 5-bromolevulinate; and b) hydrolyzing the quaternary ammonium salt with an inorganic acid to form an acid addition salt of delta-aminolevulinic acid.

Moens, Luc (Lakewood, CO)

2003-06-24

194

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

195

Malonic ester and acetoacetic ester synthesis of 2-[11,14C]methyl-fatty acids  

International Nuclear Information System (INIS)

Suitable conditions were sought for the synthesis of various 2-[11,14C]methyl-fatty acids by malonic ester synthesis and acetoacetic ester synthesis, both involving radio-methylation with [11,14C]CH3I. The malonic ester synthesis gave 2-[11C]methyl-fatty acids with over 60% decay-corrected yields in about 40 min and the [14C]products with somewhat higher yields at a longer time. In the acetoacetic ester synthesis, several 2-[14C]methyl-fatty acids were synthesized in 50-70% yields by the hydrolysis of the radio-methylated acetoacetates with a concentrated potassium hydroxide solution, together with by-product ketones. This hydrolysis was completed in 5 min at 70oC, whereas rather drastic conditions or a longer time were needed for the thermal decarboxylation in the malonic ester synthesis. (author)

1997-05-01

196

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

197

Impaired negative feedback suppression of bile acid synthesis in mice lacking ?Klotho  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We have generated a line of mutant mouse that lacks ?Klotho, a protein that structurally resembles Klotho. The synthesis and excretion of bile acids were found to be dramatically elevated in these mutants, and the expression of 2 key bile acid synthase genes, cholesterol 7?-hydroxylase (Cyp7a1) and sterol 12?-hydroxylase (Cyp8b1), was strongly upregulated. Nuclear receptor pathways and the enterohepatic circulation, which regulates bile acid synthesis, seemed to be largely intact; however,...

Ito, Shinji; Fujimori, Toshihiko; Furuya, Akiko; Satoh, Junko; Nabeshima, Yoko; Nabeshima, Yo-ichi

2005-01-01

198

Synthesis and properties of 1-aminocyclopropane-1,2-dicarboxylic acid and compounds incorporating it  

Energy Technology Data Exchange (ETDEWEB)

Methods for the synthesis of 1-aminocyclopropane-1,2-dicarboxylic acid derivatives including carbo- and heterocyclic compounds and peptides are analysed. Special attention is given to methods for the synthesis of individual stereoisomers of 1-aminocyclopropane-1,2-dicarboxylic acid derivatives based on the use of diastereoselective processes or enantiomerically pure starting compounds. The transformations of 1-aminocyclopropane-1,2-dicarboxylic acid derivatives which yield compounds with potential biological activities are considered.

Krasnov, Victor P; Korolyova, Marina A; Levit, Galina L [I. Ya. Postovsky Institute of Organic Synthesis, Urals Branch of the Russian Academy of Sciences, Ekaterinburg (Russian Federation)

2003-04-30

199

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 catalyst. Its purity was over 99% after high refining over activated silica gel. Total yield was estimated to be 22,8%.

Una nueva y práctica síntesis del ácido graso iso-13-metil- tetradecanoico y sus triglicéridos se describe aquí. Este iso- ácido graso se prepara a través de la elongación de la cadena del ácido undecanoico con isobutiraldehido según Wittig por reacción entre la sal de bromuro de undecanoico etil-éster trifenilfosfonio y metilato sódio seguido de la adición de isobutiraldehido. Su triglicérido está formado por la esterificación del iso ácido graso libre con glicerina sin catalizador. Su pureza es superior al 99%, después de una alta refinación sobre gel de sílice activado. El rendimiento total se estimó en el 22,8%.

Zlatanos, S.

2011-12-01

200

SYNTHESIS AND ANTIBACTERIAL ACTIVITY OF AMIDE DERIVATIVES FROM ACRYLOPIMARIC ACID  

Directory of Open Access Journals (Sweden)

Full Text Available This paper reports on the synthesis of a series of amide derivatives from acrylopimaric acid (APA. The derivatives contained aromatic groups and were characterized by IR, 1HNMR, MS, and elemental analysis. The antibacterial activity of the derivatives against Gram-negative bacteria and Gram-positive bacteria were also investigated. When compared with the other derivatives, compounds 3a and 3f showed much higher activity against Escherichia coli (Gram-negative bacteria with inhibition zones of 5 mm and 5.5 mm, respectively. Structure-activity relationship analysis revealed that ortho-substituted phenyl derivatives and meta-substituted phenyl derivatives exhibited higher activity than the para-substituted derivatives. Meanwhile, the halogen-substituted compounds did not show visible antibacterial activity compared with other compounds, which may have been caused by the lower electron density of the halogen-substituted phenyl rings.

Jian Li,

2012-02-01

 
 
 
 
201

Track regression in polyethylene terephthalate after sensitization  

International Nuclear Information System (INIS)

The influence of sensitization on track conservation in a polyethylene terephthalate film irradiated by xenon ions with energies of ?1 MeV/amu is investigated by various methods (ultraviolet irradiation and treatment with a solvent). It was found that after treatment by a solvent, the tracks rapidly regress, whereas after ultraviolet irradiation the tracks remain stable for ten years

1993-03-01

202

Infrared properties of polyethylene terephthalate films  

Energy Technology Data Exchange (ETDEWEB)

The infrared radiation properties of polyethylene terephthalate films are calculated from the optical constants. Hemispherical total transmittance and emittance are given as functions of thickness. The difference between these properties and those of glass will significantly affect the thermal conductance of windows or solar collector covers.

Rubin, M.

1982-03-01

203

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

204

Ceramide synthesis from free fatty acids in rat brain: function of NADPH and substrate specificity  

Energy Technology Data Exchange (ETDEWEB)

At the subcellular level, the synthesis of ceramide from free lignoceric acid and sphingosine in brain required reconstituted enzyme system (particulate fraction, heat-stable and heat-labile factors) and pyridine nucleotide (NADPH). The mitochondrial electron transfer inhibitors (KCN and antimycin A), energy uncouplers (oligomycin and 2,4-dinitrophenol), and carboxyatractyloside, which prevents the transport of ATP and ADP through the mitochondrial wall, inhibit the synthesis of ceramide in the presence of NADPH but have very little effect in the presence of ATP. Similar to the synthesis of ceramide, the synthesis of ATP from NADPH and NADH by the particulate fraction also required cytoplasmic factors (heat-stable and heat-labile factors). Moreover, ATP, but not its analog (AMP-CH2-P-O-P), can replace NADPH, thus suggesting that the function of the pyridine nucleotide is to provide ATP for the synthesis of ceramide. The cytoplasmic factors were not required for the synthesis of ceramide in the presence of ATP. The maximum velocity for synthesis of ceramide from free fatty acids of different chain lengths (C16-C26) was bimodal, with maxima around stearic acid (C18) and behenic acid (C22). The relative rate of synthesis of ceramide parallels the relative distribution of these fatty acids in brain cerebrosides and sulfatides.

Singh, I.

1983-06-01

205

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

206

Regulation of protein synthesis by amino acids in muscle of neonates.  

Science.gov (United States)

The marked increase in skeletal muscle mass during the neonatal period is largely due to a high rate of postprandial protein synthesis that is modulated by an enhanced sensitivity to insulin and amino acids. The amino acid signaling pathway leading to the stimulation of protein synthesis has not been fully elucidated. Among the amino acids, leucine is considered to be a principal anabolic agent that regulates protein synthesis. mTORC1, which controls protein synthesis, has been implicated as a target for leucine. Until recently, there have been few studies exploring the role of amino acids in enhancing muscle protein synthesis in vivo. In this review, we discuss amino acid-induced protein synthesis in muscle in the neonate, focusing on current knowledge of the role of amino acids in the activation of mTORC1 leading to mRNA translation. The role of the amino acid transporters, SNAT2, LAT1, and PAT, in the modulation of mTORC1 activation and the role of amino acids in the activation of putative regulators of mTORC1, i.e., raptor, Rheb, MAP4K3, Vps34, and Rag GTPases, are discussed. PMID:21196241

Suryawan, Agus; Davis, Teresa A

2011-01-01

207

The selective generation of acetic acid directly from synthesis gas  

International Nuclear Information System (INIS)

The authors conclude that each of the ruthenium, cobalt and iodide-containing catalyst components have very specific roles to play in the ''melt'' catalyzed conversion of synthesis gas to acetic acid. C_1-Oxygenate formation is only observed in the presence of ruthenium carbonyls - [Ru(CO)_3I_3]"- is here the dominant species - and there is a direct relationship between liquid yield, ?OAc"-productivity and [Ru(CO)_3I_3]"- content. Controlled quantities of iodide ensure that initially formed MeOH is rapidly converted to the more reactive methyl iodide. Subsequent cobalt-catalyzed carbonylation to acetic acid may be preparatively attractive (>80% selectivity, good yields) relative to competing syntheses, where the [Co(CO)_4]"- concentration is maximized that is, where the Co/Ru ratio is >1, the syngas feedstock is rich in CO, and the initial iodide/cobalt ratios are ca. unity. Formation of cobalt-iodide species appears to be a competing, inhibitory step in this catalysis

1986-03-01

208

Synthesis and testing of partially lipophilic polyaminocarboxylic acids  

International Nuclear Information System (INIS)

Polyaminocarboxylic acids derived from diethylenetriamine and triethylenetetramine containing a lipophilic group have been synthesized. Compounds derived from triethylenetetramine were more effective in removing Pu in vitro from liver constituents labeled in vivo than those derived from diethylenetriamine. Alkylated acids showed a greater efficacy than their nonsubstituted counterparts. The greater efficacy was confirmed in a pilot experiment in rats with aged burdens of 241Am. The relative effectiveness of a number of structurally related chelons as well as combinations of chelating agents for the removal of 239Pu and 241Am from high molecular weight liver proteins has been reported earlier. The efficacy of a chelating agent for the decorporation of potentially harmful metal ions is dependent on three factors: the affinity of the chelon for the respective metal ion, the ability of the chelon to reach the site of metal deposition in vivo and the toxicity of the agent itself. Present experiments are directed towards the synthesis and testing of agents which have balanced hydrophilic and lipophilic properties

1977-03-31

209

Synthesis and conductivity of heptadecatungstovanadodiphosphoric heteropoly acid with Dawson structure  

Energy Technology Data Exchange (ETDEWEB)

A new solid high-proton conductor, heptadecatungstovanadodiphosphoric heteropoly acid H{sub 7}P{sub 2}W{sub 17}VO{sub 62}.28H{sub 2}O with Dawson structure was synthesized by the stepwise acidification and the stepwise addition of element solutions. The optimal proportion of component compounds in the synthesis reaction was given. The product was characterized by chemical analysis, potentiometric titration, IR, UV, XRD, {sup 31}P NMR, TG-DTA and electrochemical impedance spectroscopy (EIS). The results indicate that H{sub 7}P{sub 2}W{sub 17}VO{sub 62}.28H{sub 2}O possesses the Dawson structure. EIS measurements show a high conductivity (3.10 x 10{sup -2} S cm{sup -1} at 26 deg. C and 75% relative humidity), with an activation energy of 32.23 kJ mol{sup -1} for proton conduction. The mechanism of proton conduction for this heteropoly acid is Vehicle mechanism.

Tong Xia; Zhu Weiming [Department of Chemistry, Zhejiang University, Hangzhou 310027 (China); Wu Qingyin, E-mail: qywu@zju.edu.cn [Department of Chemistry, Zhejiang University, Hangzhou 310027 (China); Qian Xueyu; Liu Zhen [Department of Chemistry, Zhejiang University, Hangzhou 310027 (China); Yan Wenfu [State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, Jilin University, Changchun 130012 (China); Gong Jian [Key Lab of Polyoxometalate Science, the Ministry of Education, Northeast Normal University, Changchun 130024 (China)

2011-07-21

210

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 acid and base catalysts, respectively. © 2013 BCREC UNDIP. All rights reserved

Hartati, Hartati

2013-06-01

211

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 0.2...

El-waziry, A. M.

2012-01-01

212

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

Science.gov (United States)

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 purification of synthetic intermediates, a fluorous-assisted strategy has been also explored. Using this approach, a hyaluronic acid trisaccharide was prepared. PMID:24930061

Macchione, Giuseppe; de Paz, José L; Nieto, Pedro M

2014-07-23

213

Isolation, structure, and synthesis of viridic acid, a new tetrapeptide mycotoxin of Penicillium viridicatum Westling  

International Nuclear Information System (INIS)

The isolation of a new toxic metabolite, viridic acid, from Penicillium viridicatum Westling is described. The chemical and spectroscopic properties of the compound are interpreted in terms of the tetrapeptide structure (N,N-dimethyl-o-aminobenzoyl)-glycyl-(N'-methyl-L-valyl)-o-aminobenzoic acid. The structure and chirality of viridic acid were confirmed by total synthesis

1986-01-01

214

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

1981-01-01

215

A biomimetic approach to the synthesis of a mycolic acid motif  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A new method for the stereoselective synthesis of the (R,R)-b-hydroxy-a-alkyl fatty acid fragment of mycolic acids, via an asymmetric anti-aldol reaction is reported. The ‘mycolic acid motif’ fragment was prepared in three steps and >98% ee.

Driver, Kathy; Balogun, Mohammed O.; Toschi, Gianna; Verschoor, J. A.; Baird, Mark S.; Pilcher, Lynne A.

2010-01-01

216

DFT study of the Lewis acid mediated synthesis of 3-acyltetramic acids.  

Science.gov (United States)

The synthesis of 3-acyltetramic acids by C-acylation of pyrrolidine-2,4-diones was studied by density functional theory (DFT). DFT was applied to the mycotoxin tenuazonic acid (TeA), an important representative of these bioactive natural compounds. Lewis acid mediated C-acylation in combination with previous pH-neutral domino N-acylation-Wittig cyclization can be used for the efficient preparation of 3-acyltetramic acids. Nevertheless, quite harsh conditions are still required to carry out this synthetic step, leading to unwanted isomerization of stereogenic centers in some cases. In the presented study, the reaction pathway for the C-acetylation of (5S,6S-5-s-butylpyrrolidine-2,4-dione was studied in terms of mechanism, solvent effects, and Lewis acid activation, in order to obtain an appropriate theoretical model for further investigations. Crucial steps were identified that showed rather high activation barriers and rationalized previously reported experimental discoveries. After in silico optimization, aluminum chlorides were found to be promising Lewis acids that promote the C-acylation of pyrrolidine-2,4-diones, whereas calculations performed in various organic solvents showed that the solvent had only a minor effect on the energy profiles of the considered mechanisms. This clearly indicates that further synthetic studies should focus on the Lewis-acidic mediator rather than other reaction parameters. Additionally, given the results obtained for different reaction routes, the stereochemistry of this C-acylation is discussed. It is assumed that the formation of Z-configured TeA is favored, in good agreement with our previous studies. PMID:24794137

Mikula, Hannes; Svatunek, Dennis; Skrinjar, Philipp; Horkel, Ernst; Hametner, Christian; Fröhlich, Johannes

2014-05-01

217

Tailored fatty acid synthesis via dynamic control of fatty acid elongation  

Science.gov (United States)

Medium-chain fatty acids (MCFAs, 4–12 carbons) are valuable as precursors to industrial chemicals and biofuels, but are not canonical products of microbial fatty acid synthesis. We engineered microbial production of the full range of even- and odd-chain–length MCFAs and found that MCFA production is limited by rapid, irreversible elongation of their acyl-ACP precursors. To address this limitation, we programmed an essential ketoacyl synthase to degrade in response to a chemical inducer, thereby slowing acyl-ACP elongation and redirecting flux from phospholipid synthesis to MCFA production. Our results show that induced protein degradation can be used to dynamically alter metabolic flux, and thereby increase the yield of a desired compound. The strategy reported herein should be widely useful in a range of metabolic engineering applications in which essential enzymes divert flux away from a desired product, as well as in the production of polyketides, bioplastics, and other recursively synthesized hydrocarbons for which chain-length control is desired.

Torella, Joseph P.; Ford, Tyler J.; Kim, Scott N.; Chen, Amanda M.; Way, Jeffrey C.; Silver, Pamela A.

2013-01-01

218

Tailored fatty acid synthesis via dynamic control of fatty acid elongation.  

Science.gov (United States)

Medium-chain fatty acids (MCFAs, 4-12 carbons) are valuable as precursors to industrial chemicals and biofuels, but are not canonical products of microbial fatty acid synthesis. We engineered microbial production of the full range of even- and odd-chain-length MCFAs and found that MCFA production is limited by rapid, irreversible elongation of their acyl-ACP precursors. To address this limitation, we programmed an essential ketoacyl synthase to degrade in response to a chemical inducer, thereby slowing acyl-ACP elongation and redirecting flux from phospholipid synthesis to MCFA production. Our results show that induced protein degradation can be used to dynamically alter metabolic flux, and thereby increase the yield of a desired compound. The strategy reported herein should be widely useful in a range of metabolic engineering applications in which essential enzymes divert flux away from a desired product, as well as in the production of polyketides, bioplastics, and other recursively synthesized hydrocarbons for which chain-length control is desired. PMID:23798438

Torella, Joseph P; Ford, Tyler J; Kim, Scott N; Chen, Amanda M; Way, Jeffrey C; Silver, Pamela A

2013-07-01

219

Synthesis of L-ascorbic acid in the phloem  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Although plants are the main source of vitamin C in the human diet, we still have a limited understanding of how plants synthesise L-ascorbic acid (AsA and what regulates its concentration in different plant tissues. In particular, the enormous variability in the vitamin C content of storage organs from different plants remains unexplained. Possible sources of AsA in plant storage organs include in situ synthesis and long-distance transport of AsA synthesised in other tissues via the phloem. In this paper we examine a third possibility, that of synthesis within the phloem. Results We provide evidence for the presence of AsA in the phloem sap of a wide range of crop species using aphid stylectomy and histochemical approaches. The activity of almost all the enzymes of the primary AsA biosynthetic pathway were detected in phloem-rich vascular exudates from Cucurbita pepo fruits and AsA biosynthesis was demonstrated in isolated phloem strands from Apium graveolens petioles incubated with a range of precursors (D-glucose, D-mannose, L-galactose and L-galactono-1,4-lactone. Phloem uptake of D-[U-14C]mannose and L-[1-14C]galactose (intermediates of the AsA biosynthetic pathway as well as L-[1-14C]AsA and L-[1-14C]DHA, was observed in Nicotiana benthamiana leaf discs. Conclusions We present the novel finding that active AsA biosynthesis occurs in the phloem. This process must now be considered in the context of mechanisms implicated in whole plant AsA distribution. This work should provoke studies aimed at elucidation of the in vivo substrates for phloem AsA biosynthesis and its contribution to AsA accumulation in plant storage organs.

Haupt Sophie

2003-11-01

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76 FR 47558 - 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...Countervailing Duty Order: Polyethylene Terephthalate Film, Sheet, and...

2011-08-05

 
 
 
 
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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

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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

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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

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

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2013-08-16

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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

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

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2010-12-28

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

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2010-10-25

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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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77 FR 73010 - Polyethylene Terephthalate Film, Sheet, and Strip From the United Arab Emirates; Preliminary...  

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2012-12-07

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75 FR 78968 - Polyethylene Terephthalate Film, Sheet, and Strip From the United Arab Emirates: Preliminary...  

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...Administration [A-520-803] Polyethylene Terephthalate Film, Sheet, and Strip...antidumping duty order on polyethylene terephthalate film, sheet, and strip...Film from the UAE. See Polyethylene Terephthalate Film, Sheet, and...

2010-12-17

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

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2011-02-22

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76 FR 47546 - 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...

2011-08-05

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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

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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

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78 FR 48143 - 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...Administrative Review: Polyethylene Terephthalate Film, Sheet, and...

2013-08-07

237

75 FR 49900 - 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...film from Brazil. See Polyethylene Terephthalate Film, Sheet, and...

2010-08-16

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

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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...

2012-04-02

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2013-12-26

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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

 
 
 
 
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2013-12-24

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

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2010-08-16

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

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2011-07-08

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

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2010-03-09

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

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2011-05-27

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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

247

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

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2010-12-02

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76 FR 27005 - Polyethylene Terephthalate Film, Sheet, and Strip From the Republic of Korea: Initiation and...  

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2011-05-10

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2013-08-07

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

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2012-12-10

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2011-11-25

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

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2010-07-14

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

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2011-08-08

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

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2012-08-06

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

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...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

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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

257

76 FR 76365 - Polyethylene Terephthalate Film, Sheet, and Strip From the United Arab Emirates: Preliminary...  

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...Administration [A-520-803] Polyethylene Terephthalate Film, Sheet, and Strip...antidumping duty order on polyethylene terephthalate film, sheet, and strip...Film from the UAE. See Polyethylene Terephthalate Film, Sheet, and...

2011-12-07

258

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

259

75 FR 52717 - 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...

2010-08-27

260

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

 
 
 
 
261

76 FR 47540 - 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...Antidumping Duty Order: Polyethylene Terephthalate Film, Sheet, and...

2011-08-05

262

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

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...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

263

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

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...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

264

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

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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...

2011-12-09

265

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

266

76 FR 61085 - 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 of polyethylene terephthalate film, sheet, and strip...review by 60 days. See Polyethylene Terephthalate Film, Sheet, and...

2011-10-03

267

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

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...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

268

77 FR 3730 - Polyethylene Terephthalate Film, Sheet and Strip From India: Rescission, in Part, 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...September 20, 2011. See Polyethylene Terephthalate Film, Sheet and...

2012-01-25

269

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

270

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

271

75 FR 81574 - 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...Countervailing Duty Order: Polyethylene Terephthalate Film, Sheet and...

2010-12-28

272

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

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...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

273

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

274

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

275

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

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...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

276

75 FR 6634 - 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...countervailing duty order on polyethylene terephthalate film, sheet, and strip...December 31, 2007. See Polyethylene Terephthalate Film, Sheet, and...

2010-02-10

277

75 FR 49893 - Polyethylene Terephthalate Film, Sheet, and Strip From the People's Republic of China...  

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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 also Polyethylene Terephthalate Film, Sheet, and...

2010-08-16

278

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

279

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

Science.gov (United States)

...Intracardiac patch or pledget made of polypropylene, polyethylene terephthalate, or polytetrafluoroethylene...Intracardiac patch or pledget made of polypropylene, polyethylene terephthalate, or polytetrafluoroethylene...intracardiac patch or pledget made of polypropylene, polyethylene terephthalate,...

2010-04-01

280

Synthesis and cytotoxic activity of new betulin and betulinic acid esters with conjugated linoleic acid (CLA).  

Science.gov (United States)

The synthesis of new ester derivatives of betulin (3a-c) and betulinic acid (4) with conjugated linoleic acid isomers (CLA; in a mixture of 43.4% 9c, 11t; 49.5% 10t, 12c; 7.1% other isomers) is presented. Esterification was carried out with N,N'-dicyclohexylcarbodiimide (DCC) as the coupling agent in the presence of 4-dimethylamino-pyridine (DMAP) in dichloromethane (or pyridine). The in vitro cytotoxic effect of betulin (1), betulinic acid (2), a mixture of CLA isomers and their derivatives (3a-c, 4) was examined using the MTT assay against four cancer cell lines (P388, CEM/C2, CCRF/CEM and HL-60) and the SRB assay on the HT-29 cell line. Ester 4 was the most active among the esters synthesized against the CEM/C2 cell line with an ID50 value 16.9 +/- 6.5 microg/mL. Betulin (1), betulinic acid (2) and CLA were the most active agents against the cancer cell lines studied. PMID:23738445

Tubek, Barbara; Mitu?a, Pawe?; Niezgoda, Natalia; Kempi?ska, Katarzyna; Wietrzyk, Joanna; Wawrze?czyk, Czes?aw

2013-04-01

 
 
 
 
281

Convergent approach to complex spirocyclic pyrans: practical synthesis of the oxa-pinnaic acid core.  

Science.gov (United States)

The enantioselective synthesis of the oxa-pinnaic acid framework has been achieved through internal asymmetric induction. The synthetic strategy pursued illustrates the adaptability of the Achmatowicz oxidative rearrangement for the synthesis of complex spirocyclic pyrans starting from tertiary alcohols. PMID:23589153

Ferrari, Frank D; Pasqua, Adele E; Ledgard, Andrew J; Marquez, Rodolfo

2013-06-01

282

Synthesis of D-(-)-[1,7-13C2]shikimic acid  

International Nuclear Information System (INIS)

The chemical synthesis of 99% enriched D(-)-[1,7-13C2]shikimic acid from [1,2-13C2]acetate in 25% overall yield is described. A two-carbon phosphonate synthon was prepared from [1,2-13C2]acetate and used in the shikimate synthesis of Fleet et al. (author)

1992-08-01

283

Effect of fatty acids on the synthesis and secretion of apolipoprotein B by rat hepatocytes  

International Nuclear Information System (INIS)

The modulation of apolipoprotein B synthesis and secretion by fatty acids in rat hepatocytes was studied. Maximum apolipoprotein B production was obtained in the case of oleic acid followed by linoleic, stearic and palmitic/linolenic acid when compared to control which was not supplemented with any fatty acids. Oleic acid was found to exert a concentration dependent increase in the secretion of [3H] apolipoprotein B into the medium while that associated with the cell layer was not affected. Pulse chase experiments in the presence of oleic acid showed that it caused an increase in the secretion of apolipoprotein B into the medium. 14C-acetate incorporation into cholesterol and cholesteryl ester associated with the cell layer and secreted very low density lipoproteins also showed an increase in the presence of oleic acid indicating an increase in cholesterogenesis. The effect of oleic acid on [3H] apolipoprotein B and very low density lipoprotein secretion appeared to be mediated through cholesterol as (i)ketoconazole, an inhibitor of cholesterol synthesis caused significant reduction in the stimulatory effect of oleic acid on apolipoprotein secretion and (ii) mevinolin, another inhibitor of cholesterol synthesis also reversed the stimulatory effect of oleic acid on apolipoprotein B secretion. These results indicated that oleic acid may influence apolipoprotein B synthesis and secretion in hepatocytes probably by affecting cholesterol/cholesteryl ester formation which may be a critical component in the secretion of apolipoprotein B as lipoproteins. (author). 21 refs., 4 figs., 2 tabs

1992-12-01

284

Orotic acid: its influence on nuclear RNA and microsomal protein synthesis in brain cells of undernourished rat pups.  

Science.gov (United States)

Malnourished rat pups were supplemented with orotic acid. RNA-synthesizing activity of isolated brain cell nuclei and microsomal protein synthesis was measured in vitro. A marked increase was found in the activity of nuclear RNA synthesis but not in microsomal protein synthesis after orotic acid treatment for 7 days. PMID:656522

Lipp, K; van der Meulen, N; Wenske, G; Linneweh, F

1978-01-01

285

An approach to the synthesis of C18 tri-insaturated fatty acids.  

Science.gov (United States)

New approaches for the synthesis of cis, trans, trans, octadeca-9,11,13-trienoic acid (I) and its trans, trans, cis isomer (II), starting from the easily available propargyl alcohol are described. PMID:902757

Petragnani, N; Brocksom, T J; Gato, A R

1977-09-01

286

Synthesis of benzannulated heterocycles by twofold Suzuki-Miyaura couplings of cyclic diarylborinic acids.  

Science.gov (United States)

Two-fold Suzuki-Miyaura cross-couplings of cyclic diarylborinic acids are described. This novel annulation method enables the synthesis of benzo-fused heterocycles from dihaloarenes or gem-dibromoolefins. PMID:24473678

Dimitrijevi?, Elena; Cusimano, Madeline; Taylor, Mark S

2014-03-01

287

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)

2006-10-15

288

Effect of amino acid deprivation on initiation of protein synthesis in rat hepatocytes  

Energy Technology Data Exchange (ETDEWEB)

Conditions were defined for maintaining optimal protein synthetic activity in suspensions of freshly isolated rat hepatocytes. Under these conditions, isolated hepatocytes exhibited rates of protein synthesis and levels of polysomal aggregation equivalent to those observed in vivo and in perfused liver. Deprivation of total amino acids or single, essential amino acids resulted in a rapid decrease in the rate of protein synthesis, which was readily reversed by readdition of the deficient amino acid(s). The decrease was accompanied by a disaggregation of polysomes and an inhibition of 43S initiation complex formation, which was indicative of a limitation in the rate of initiation of protein synthesis. Extracts prepared from perfused liver deprived of amino acids were inhibitory to initiation of protein synthesis in reticulocyte lysate. The inhibition in reticulocyte lysate was accompanied by an increase in phosphorylation of the alpha-subunit of eukaryotic initiation factor 2 (eIF-2), suggesting activation of an eIF-2 alpha kinase or inhibition of a phosphatase in amino acid-deprived hepatocytes. This suggestion was confirmed by prelabeling hepatocytes with /sup 32/Pi before amino acid deprivation. Incorporation of /sup 32/Pi into eIF-2 alpha was two- to threefold higher in lysine-deprived cells than in hepatocytes incubated in fully supplemented medium. Overall, the results indicated that an increase in eIF-2 alpha phosphorylation was responsible for the defect in initiation of protein synthesis caused by amino acid deprivation.

Everson, W.V.; Flaim, K.E.; Susco, D.M.; Kimball, S.R.; Jefferson, L.S.

1989-01-01

289

Effect of amino acid deprivation on initiation of protein synthesis in rat hepatocytes  

International Nuclear Information System (INIS)

Conditions were defined for maintaining optimal protein synthetic activity in suspensions of freshly isolated rat hepatocytes. Under these conditions, isolated hepatocytes exhibited rates of protein synthesis and levels of polysomal aggregation equivalent to those observed in vivo and in perfused liver. Deprivation of total amino acids or single, essential amino acids resulted in a rapid decrease in the rate of protein synthesis, which was readily reversed by readdition of the deficient amino acid(s). The decrease was accompanied by a disaggregation of polysomes and an inhibition of 43S initiation complex formation, which was indicative of a limitation in the rate of initiation of protein synthesis. Extracts prepared from perfused liver deprived of amino acids were inhibitory to initiation of protein synthesis in reticulocyte lysate. The inhibition in reticulocyte lysate was accompanied by an increase in phosphorylation of the alpha-subunit of eukaryotic initiation factor 2 (eIF-2), suggesting activation of an eIF-2 alpha kinase or inhibition of a phosphatase in amino acid-deprived hepatocytes. This suggestion was confirmed by prelabeling hepatocytes with 32Pi before amino acid deprivation. Incorporation of 32Pi into eIF-2 alpha was two- to threefold higher in lysine-deprived cells than in hepatocytes incubated in fully supplemented medium. Overall, the results indicated that an increase in eIF-2 alpha phosphorylation was responsible for the defect in initiation of protein synthesis caused by amino acid deprivation

1989-01-01

290

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

291

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.

2010-01-01

292

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-"1"4C]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-"1"4C]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 "3H_2O 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 of cholesteryl ester in the hepatic microsomes

1985-01-01

293

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 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)

2008-10-01

294

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

295

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

1996-07-31

296

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

297

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

298

The involvement of amino acids in latex lipid synthesis in Euphorbia lathyris seedlings  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The breakdown of triglycerides and proteins in the endosperm of Euphorbia lathyris was assayed in a 14 day germination period. Six days after germination, the average daily production was 2.7 ?mol of amino acids. Arginine, glutamine, asparagine and glutamic acid accounted for 53% of the total amino acids. Excised cotyledons with 1 cm hypocotyls were used for amino acid uptake and their involvement in terpenoid synthesis was studied. Glutamine and aspartate were hardly involved in apolar lipi...

Groeneveld, H. W.; Elings, J.

1984-01-01

299

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...

2013-01-01

300

Abc Amino Acids: Design, Synthesis, and Properties of New Photoelastic Amino Acids  

Energy Technology Data Exchange (ETDEWEB)

Photoisomerizable amino acids provide a direct avenue to the experimental manipulation of bioactive polypeptides, potentially allowing real-time, remote control of biological systems and enabling useful applications in nanobiotechnology. Herein, we report a new class of photoisomerizable amino acids intended to cause pronounced expansion and contraction in the polypeptide backbone, i.e., to be photoelastic. These compounds, termed Abc amino acids, employ a photoisomerizable azobiphenyl chromophore to control the relative disposition of aminomethyl and carboxyl substituents. Molecular modeling of nine Abc isomers led to the identification of one with particularly attractive properties, including the ability to induce contractions up to 13A in the backbone upon transa?cis photoisomerization. This isomer, designated mpAbc, has substituents at meta and para positions on the inner (azo-linked) and outer rings, respectively. An efficient synthesis of Fmoc-protected mpAbc was executed in which the biaryl components were formed via Suzuki couplings and the azo linkage was formed via amine/nitroso condensation; protected forms of three other Abc isomers were prepared similarly. A decapeptide incorporating mpAbc was synthesized by conventional solid-phase methods and displayed characteristic azobenzene photochemical behavior with optimal conversion to the cis isomer at 360 nm and a thermal cisa?trans half life of 100 min. at 80 AoC.

Standaert, Robert F [ORNL; Park, Dr Seung Bum [Seoul National University

2006-01-01

 
 
 
 
301

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 synthesi [...] zed by using 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.

Rafiee, Ezzat; Kahrizi, Masoud.

302

Thermal synthesis and hydrolysis of polyglyceric acid. [in orgin of life studying  

Science.gov (United States)

Polyglyceric acid was synthesized by thermal condensation of glyceric acid at 80 C in the presence and absence of two mole percent of sulfuric acid catalyst. The acid catalyst accelerated the polymerization over 100-fold and made possible the synthesis of insoluble polymers of both L- and DL-glyceric acid by heating for less than 1 day. Racemization of L-glyceric acid yielded less than 1 percent D-glyceric acid in condensations carried out at 80 C with catalyst for 1 day and without catalyst for 12 days. The condensation of L-glyceric acid yielded an insoluble polymer much more readily than condensation of DL-glyceric acid. Studies of the hydrolysis of poly-DL-glyceric acid revealed that it was considerably more stable under mild acidic conditions compared to neutral pH. The relationship of this study to the origin of life is discussed.

Weber, Arthur L.

1989-01-01

303

[Abiogenic photochemical synthesis of amino acids in an aqueous medium containing carbohydrates and nitrates].  

Science.gov (United States)

Ultraviolet light (PRK-2) induces the formation of various amino acids (lysine, asparaginic, as well as traces of some other acids) in mannose, glucose and arabinose solutions containing various nitrates. K+, Co2+, Ni2+ and Fe3+ significantly sensitize the formation of amino acids. In the atmosphere of N2, synthesis of appreciable amounts of glutamic acid takes place, wherease in the atmosphere of O2 or CO2 the latter is produced only in traces. Photolysis of glucose and mannose in nitrate-free solutions in the atmosphere of N2 results in the formation of lysine and glutamic acid. The data obtained show that in pre-biologic conditions in the hydrosphere of Earth (possibly, of other planets as well), abiogenically formed organic substances, e. g. carbohydrates, unter the influence of UV irradiation could be transformed into amino acids. Nitrates present in the water milieu could serve as a source of nitrogen in the amino acids synthesis. PMID:868388

Khenokh, M A; Nikolaeva, M V

1977-01-01

304

Synthesis of the Demospongic Compounds, (6Z, 11Z-Octadecadienoic Acid and (6Z, 11Z-Eicosadienoic Acid  

Directory of Open Access Journals (Sweden)

Full Text Available A stereoselective synthesis of (6Z, 11Z-octadecadienoic acid (1 and (6Z, 11Z-eicosadienoic acid (2 from easily accessible pentane-1,5-diol (3 is described. Thus, compound 3 on pyranylation and oxidation gave the aldehyde 5 which was converted to the acid 7 by Wittig reaction with a suitable phosphorane. Its depyranylation and oxidation furnished the key aldehyde 9 which upon Wittig reaction with n-heptylidene and n-nonylidene phosphoranes, respectively followed by alkaline hydrolysis afforded the title acids.

V. R. Mamdapur

1997-01-01

305

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

1987-05-01

306

Zinc mediated allylations of chlorosilanes promoted by ultrasound: Synthesis of novel constrained sila amino acids.  

Science.gov (United States)

A simple, fast and efficient method for allylation and propargylation of chlorosilanes through zinc mediation and ultrasound promotion is reported. As a direct application of the resulting bis-allylsilanes, three novel, constrained sila amino acids are prepared for the first time. The design and synthesis of the constrained sila analogue of GABA (?-amino butyric acid) is a highlight of this work. PMID:24827151

Ramesh, Remya; Reddy, D Srinivasa

2014-05-28

307

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

308

One-Flow, Multi-Step Synthesis of Nucleosides via Brønsted Acid- Catalyzed Glycosylation  

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Nucleosides in flow: A general, scalable method of Brønsted acid-catalyzed nucleoside formation is described. Because of the high reaction temperatures readily available to the flow reaction format, mild Brønsted acids, particularly pyridinium triflates, can be used. A one-flow multistep synthesis of unprotected nucleosides is also reported (see scheme).

Sniady, Adam; Bedore, Matthew W.; Jamison, Timothy F.

2010-01-01

309

Enhancing effect of 2-O-alpha-D-glucopyranosyl-L-ascorbic acid, a stable ascorbic acid derivative, on collagen synthesis.  

Science.gov (United States)

The objective of the present study was to compare 2-O-alpha-D-glucopyranosyl-L-ascorbic acid (AA-2G) with ascorbic acid (AA) and ascorbic acid 2-phosphate (AA-2P) concerning the promotion of collagen production in human skin fibroblasts. Though AA-2G was still observed to be promoting collagen synthesis at the same level on the 8th day of the culture, collagen synthesis was seen to decrease on the fifth day of culturing with AA and AA-2P. This sustained collagen synthesis-promoting action is considered to be a major feature of the novel vitamin C derivative, AA-2G by conducting an experiment in which an alpha-glucosidase inhibitor was present, it was shown that AA-2G exerts its collagen synthesis-promoting action after being decomposed to AA by alpha-glucosidase. Further, we observed that for AA-2G, even on the 8th day of the culture, the amount of AA in the fibroblasts was virtually unchanged from the beginning of the experiment, whereas, in the case of adding AA and AA-2P, virtually no AA was detectable in the culture medium on the fifth day. These findings suggests that AA-2G is decomposed to AA by alpha-glucosidase in the cells. This AA promotes collagen synthesis, which is prolonged through AA-2G's sustained decomposition. PMID:9703245

Kumano, Y; Sakamoto, T; Egawa, M; Tanaka, M; Yamamoto, I

1998-07-01

310

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

1986-05-29

311

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

312

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

313

Effects of cyanide on rates and products of fatty acid synthesis by chloroplasts isolated from Spinacia oleracea  

Energy Technology Data Exchange (ETDEWEB)

Cyanide inhibited unesterified fatty acid synthesis but stimulated glyceride synthesis from (1-/sup 14/C) acetate when Spinacia oleracea chloroplasts were incubated in basal media. Both unesterified fatty acid and glyceride accumulation were inhibited when chloroplasts were incubated in a diacylglycerol mode. Stimulation of chloroplast fatty acid synthesis by either exogenous coenzyme A or Triton X-100 was almost completely abolished in the presence of cyanide. Stearoyl-ACP desaturation is considered to be inhibited to a greater extent than is fatty acid synthesis de novo.

Roughan, P.G.; Beevers, H.

1981-05-01

314

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%.

2011-03-31

315

Prebiotic Synthesis of Hydrophobic and Protein Amino Acids  

Science.gov (United States)

The formation of amino acids by the action of electric discharges on a mixture of methane, nitrogen, and water with traces of ammonia was studied in detail. The presence of glycine, alanine, ?-amino-n-butyric acid, ?-aminoisobutyric acid, valine, norvaline, isovaline, leucine, isoleucine, alloisoleucine, norleucine, proline, aspartic acid, glutamic acid, serine, threonine, allothreonine, ?-hydroxy-?-aminobutyric acid, and ?,?-diaminobutyric acid was confirmed by ion-exchange chromatography and gas chromatography-mass spectrometry. All of the primary ?-amino acids found in the Murchison Meteorite have been synthesized by this electric discharge experiment.

Ring, David; Wolman, Yecheskel; Friedmann, Nadav; Miller, Stanley L.

1972-01-01

316

Synthesis of a diastereomeric mixture of deuterium-labeled lovastatin and its acid ammonium salt  

International Nuclear Information System (INIS)

In this communication, a facile synthesis for (2S/2R)-[2H3]lovastatin and (2S/2R)-[2H3]lovastatin acid ammonium salt was described. The stable isotope-labeled (2S/2R)-lovastatin and its acid ammonium salt were prepared from butyric acid via several reaction steps with 11.1 and 6.3 % overall yield, respectively. (author)

2014-05-01

317

Metabolic basis for the differential susceptibility of Gram-positive pathogens to fatty acid synthesis inhibitors  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The rationale for the pursuit of bacterial type 2 fatty acid synthesis (FASII) as a target for antibacterial drug discovery in Gram-positive organisms is being debated vigorously based on their ability to incorporate extracellular fatty acids. The regulation of FASII by extracellular fatty acids was examined in Staphylococcus aureus and Streptococcus pneumoniae, representing two important groups of pathogens. Both bacteria use the same enzymatic tool kit for the conversion of extracellular fa...

Parsons, Joshua B.; Frank, Matthew W.; Subramanian, Chitra; Saenkham, Panatda; Rock, Charles O.

2011-01-01

318

Synthesis of conformationally constrained hydroxy-alpha-amino acids by intramolecular conjugate addition.  

Science.gov (United States)

An efficient and easily applicable method for the synthesis of a variety of hydroxy-alpha-amino acids analogues of serine and phenylalanine has been established. The method involves the stereoselective intramolecular conjugate addition of the benzamide group to cyclohexenone promoted by Lewis acid. Subsequent transformations of functional groups provide the conformationally constrained 2-hydroxy- and 2,4-dihydroxy-6-phenylcyclohexane-alpha-amino acids. PMID:10817404

Avenoza, A; Busto, J H; Cativiela, C; Peregrina, J M

2000-01-01

319

Effects of acanthoic acid on TNF-alpha gene expression and haptoglobin synthesis.  

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Tumour necrosis factor-alpha (TNF-alpha) is a major pro-inflammatory cytokine inducing the synthesis and release of many inflammatory mediators. It is involved in immune regulation, autoimmune diseases, and inflammation. Our previous study demonstrated that acanthoic acid, (-)-pimara-9(11), 15-dien-19-oic acid, a pimaradiene diterpene isolated from Acanthopanax koreanum, inhibited TNF-alpha production. To extend our understanding of inhibitory effects of acanthoic acid on TNF-alpha production...

Kang, H. S.; Song, H. K.; Lee, J. J.; Pyun, K. H.; Choi, I.

1998-01-01

320

Dependence of Arbuscular-Mycorrhizal Fungi on Their Plant Host for Palmitic Acid Synthesis  

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Lipids are the major form of carbon storage in arbuscular-mycorrhizal fungi. We studied fatty acid synthesis by Glomus intraradices and Gigaspora rosea. [14C]Acetate and [14C]sucrose were incorporated into a synthetic culture medium to test fatty acid synthetic ability in germinating spores (G. intraradices and G. rosea), mycorrhized carrot roots, and extraradical fungal mycelium (G. intraradices). Germinating spores and extraradical hyphae could not synthesize 16-carbon fatty acids but could...

Tre?panier, Martin; Be?card, Guillaume; Moutoglis, Peter; Willemot, Claude; Gagne?, Serge; Avis, Tyler J.; Rioux, Jacques-andre?

2005-01-01

 
 
 
 
321

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

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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

322

Synthesis of 9-cis-retinoic acid and C-20-[3H3C]-9-cis-retinoic acid with high specific activity  

International Nuclear Information System (INIS)

The synthesis of 9-cis-retinoic acid starting from 2,2,6-tri methylcyclohexanone is described. The same methodology was extended for the synthesis of deuterium and tritium labeled 9-cis-retinoic acid with high specific activity (73 Ci/mmol). In this methodology, a Grignard reaction was utilized for introducing three tritium atoms simultaneously in the final synthetic steps. (Author)

1997-01-01

323

Xenograft Studies of Fatty Acid Synthesis Inhibition as Novel Therapy for Breast Cancer.  

Canada Institute for Scientific and Technical Information (Canada)

Many common human cancers express high levels of fatty acid synthase (FAS), the primary enzyme responsible for the synthesis of fatty acids. Compared to cancer, fatty acid synthesis is highly down- regulated in normal tissues by dietary fat leading to a potential therapeutic index. Inhibition of FAS with cerulenin, a suicide inhibitor of FAS, induced apoptosis in cancer cells in vitro, demonstrating that cancer cells are dependent upon active fatty acid synthesis. To test the systemic effect of FAS inhibition on human cancer xenografts, synthesis of a chemically stable inhibitor was required. Based on the probable mechanism of action of cerulenin and the theoretical transition-state of the of the Beta-ketoacyl synthase reaction, we synthesized the first chemically stable inhibitor of FAS, C75. C75 is a slow-binding inhibitor of Type I mammalian FAS. In addition to its in vitro activity against cancer cells, C75 demonstrated significant anti-cancer activity in the MDA435/LCC6 and MCF-7 human breast cancer xenografts. C75 induced transient inanition which led to weight loss reversible with nutritional support. No other significant toxicity was identified. These data illustrates C75 anti-tumor activity, and demonstrate that the fatty acid synthesis pathway and FAS in particular are novel targets for breast cancer therapy.

1998-01-01

324

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

1994-01-01

325

Synthesis of 18F-FDG using improved single-pot acid hydrolysis process  

International Nuclear Information System (INIS)

In order to explore an optimum condition to increase the synthesis yield of 2-18F-2-deoxy-?-D-glucose (18F-FDG) by using improved single-pot acid hydrolysis Chemistry Process Control Unit (CPCU), various production conditions such as the reaction temperature, the time of acid hydrolysis and others were tested. The results showed that the determinant factor which affects the synthesis yield was the quantities of water present in reaction media. The total 18F-FDG synthesis time could be minimized by effective dehydration step and regulating the amount of hydrogen chloride. The synthesis yield could be increased by improving the production conditions of 18F-FDG. (authors)

2007-12-01

326

Uric acid synthesis by rat liver supernatants from purine bases, nucleosides and nucleotides. Effect of allopurinol.  

Science.gov (United States)

The synthesis of uric acid from purine bases, nucleosides and nucleotides has been measured in reaction mixtures containing rat liver supernatant and each one of the following compounds at 1 mM concentration (except xanthine, 0.5 mM and guanosine and guanine, 0.1 mM). The rates of the reaction, expressed as nanomoles of uric acid synthesized g-1 of wet liver min-1 were: ATP, 10; ADP, 37; AMP, 62; adenosine, 108; adenine 6; adenylosuccinate, 9; IMP 32; inosine, 112; hypoxanthine, 50; GTP, 19; GDP, 19; GMP, 27; guanosine, 34; guanine, 72; XMP, 10; xanthosine, 24; xanthine, 144. These figures divided by 55 correspond to nanomoles of uric acid synthesized min-1 per mg-1 of protein. The rate of synthesis of uric acid obtained with each one of those compounds at 0.1 and 0.05 mM concentrations was also determined. ATP (1 mM) strongly inhibited uric acid synthesis from 0.05 mM AMP (91 per cent) and from 0.05 mM ADP (88 per cent), but not from adenosine. CTP or UTP (1 mM) also inhibited (by more than 90 per cent) the synthesis of uric acid from 0.05 mM AMP. Xanthine oxidase was inhibited by concentrations of hypoxanthine higher than 0.012 mM. The results favour the view that the level of uric acid in plasma may be an index of the energetic state of the organism. Allopurinol, besides inhibiting uric acid synthesis, reduced the rate of degradation of AMP. The ability of crude extracts to catabolize purine nucleotides to uric acid is an important factor to be considered when some enzymes related to purine nucleotide metabolism, particularly CTP synthase, are measured in crude liver extracts. PMID:7834812

Bleisch, S; Sillero, M A; Torrecilla, A; Sillero, A

1994-12-01

327

Molecular dimensions in polyethylene terephthalate by SANS  

International Nuclear Information System (INIS)

In this communication the authors report measurements of molecular dimensions in polyethylene terephthalate (PET) from samples where the background scattering has been reduced to an acceptably small fraction of the scattering due to the labeled molecules. This has been accomplished by improvements in the sample preparation technique to reduce the concentration of heterogeneities that give rise to background scattering and also by use of high concentrations of labeled polymers. It has been shown earlier that both the radius of gyration and molecular weight can be obtained from a single concentration measurement, provided the molecular weights of the labeled and unlabeled molecules are matched

1985-03-01

328

Rates of synthesis and degradation of ribosomal ribonucleic acid during differentiation of Dictyostelium discoideum.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Synthesis of ribosomes and ribosomal ribonucleic acid (RNA) continued during differentiation of Dictyostelium discoideum concurrently with extensive turnover of ribosomes synthesized during both growth and developmental stages. We show here that the rate of synthesis of 26S and 17S ribosomal RNA during differentiation was less than 15% of that in growing cells, and by the time of sorocarp formation only about 25% of the cellular ribosomes had been synthesized during differentiation. Ribosomes...

Mangiarotti, G.; Altruda, F.; Lodish, H. F.

1981-01-01

329

A flexible light-directed DNA chip synthesis gated by deprotection using solution photogenerated acids  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Oligonucleotide microarrays or oDNA chips are effective decoding and analytical tools for genomic sequences and are useful for a broad range of applications. Therefore, it is desirable to have synthesis methods of DNA chips that are highly flexible in sequence design and provide high quality and general adoptability. We report herein, DNA microarray synthesis based on a flexible biochip method. Our method simply uses photogenerated acid (PGA) in solution to trigger deprotection of the 5?-OH...

Gao, Xiaolian; Leproust, Eric; Zhang, Hua; Srivannavit, Onnop; Gulari, Erdogan; Yu, Peilin; Nishiguchi, Ciro; Xiang, Qin; Zhou, Xiaochuan

2001-01-01

330

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 synthesized via reaction between boric acid and various carbon precursors, e.g. phenol-formaldehyde resin, sucrose, 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 diffraction (XRD) and scanning electron microscopy. Possible boron carbide yields up to 95 % ...

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

2013-01-01

331

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

332

Malonic ester synthesis of various ?-(11,14C-methyl)-carboxylic acids and related compounds  

International Nuclear Information System (INIS)

In this paper, the authors continue the study of the malonic ester synthesis mainly of alpha-(11, 14C-methyl)-carboxylic acids and their behavior in mice. Preparation of (2-11, 14C-ethyl)-ketones is also delineated. This synthesis consists of three steps: methylation, hydrolysis, and decarboxylation. Various conditions in them were examined to find out suitable procedures for carbon-11 labelling. Labelled products were injected into mice and the organ distribution determined

1990-06-24

333

Development of an automated synthesis apparatus for L-[3-11C] labeled aromatic amino acids  

International Nuclear Information System (INIS)

We have developed an automated synthesis apparatus for L-[3-11C]-labeled aromatic amino acids by improved multi-enzymatic reactions. Use of a specially designed reaction vessel and of CH2Cl2 as a solvent has greatly simplified the overall operation, proving to be suitable for automated synthesis, and also has given better yields and higher specific activities than formerly reported values

2000-04-01

334

The synthesis of (2R)- and (2S)-[2-3H]-propionic acid  

International Nuclear Information System (INIS)

A practical synthesis of (2R)- and (2S)-[2-3H]-propionic acid is described. The key steps in the synthesis are the reduction of [formyl-3H]-3-methoxy-4-mesyloxybenzaldehyde with R- or S-Alpine Borane to (7S)- and (7R)-[7-3H]-3-methoxy-4-mesyloxybenzyl alcohol and the use of the vanillyl moiety as a masked carboxyl group. (Author)

1990-03-01

335

Synthesis of (±)-cis-clavicipitic acid by a Rh(I)-catalyzed intramolecular imine reaction.  

Science.gov (United States)

A new and short synthesis of racemic cis-clavicipitic acid was achieved by taking advantage of the double nucleophilic character of indole-4-pinacolboronic ester. Key to the success of the synthesis were an efficient and selective C-3 indole Friedel-Crafts alkylation and the development of an unprecedented intramolecular rhodium-catalyzed 1,2-addition of an aryl pinacolboronic ester to an unactivated imine. PMID:24605802

Bartoccini, Francesca; Casoli, Mariangela; Mari, Michele; Piersanti, Giovanni

2014-04-01

336

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

337

Synthesis of the Demospongic Compounds, (6Z, 11Z)-Octadecadienoic Acid and (6Z, 11Z)-Eicosadienoic Acid  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A stereoselective synthesis of (6Z, 11Z)-octadecadienoic acid (1) and (6Z, 11Z)-eicosadienoic acid (2) from easily accessible pentane-1,5-diol (3) is described. Thus, compound 3 on pyranylation and oxidation gave the aldehyde 5 which was converted to the acid 7 by Wittig reaction with a suitable phosphorane. Its depyranylation and oxidation furnished the key aldehyde 9 which upon Wittig reaction with n-heptylidene and n-nonylidene phosphoranes, respectively followed by alkaline hydrolysis aff...

Kulkarni, B. A.; Chattopadhyay, S.; Chattopadhyay, A.; Mamdapur, V. R.

1997-01-01

338

Monocyclic and monoaromatic naphthenic acids: synthesis and characterisation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Characterisation of the complex mixtures of carboxylic acids (naphthenic acids) occurring in crude oils and in degraded oil sands is environmentally important. Indeed some acids in waters from oil platforms are apparently hormonally active, and the oil sands acids are said to be toxic to a wide range of biota. Previous attempts to identify monocyclic and monoaromatic naphthenic acids have been hampered by the lack of authenticated synthetic reference compounds. Some studies have indicated tha...

2011-01-01

339

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

340

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 of LDL by the liver is intimately linked to processes activating bile acid synthesis

1989-01-01

 
 
 
 
341

Effect of testosterone on nucleic acid synthesis in spermatogenous epithelium cells of irradiated animals  

International Nuclear Information System (INIS)

A study was made of changes in nuclei acid synthesis in proliferating germ cell populations of animals irradiated with doses of 2 and 4 Gy. the administration of exogenous testosterone was shown to stimulate DNA synthesis, inhibited by the effect of radiation, in spermatogonium populations of Asub(1-4), intermediate, and B types, and in preleptotene primary spermatocytes; RNA synthesis was increased in the same populations of spermatogonia and pachytene primary spermatocytes. The obtained results indicate that exogenous testosterone exerts a benefitial effect on spermatogenesis damaged by ionizing radiation

1986-01-01

342

Enantioselective synthesis of triarylmethanes by chiral imidodiphosphoric acids catalyzed Friedel-Crafts reactions.  

Science.gov (United States)

The first enantioselective synthesis of pyrrolyl-substituted triarylmethanes has been accomplished using a novel imidodiphosphoric acid catalyst, which is derived from two (R)-BINOL frameworks with different 3,3'-substituents. This strategy was also expanded to the synthesis of bis(indolyl)-substituted triarylmethanes with high enantioselectivities, which could only be obtained with moderate ee values in previous reports. These two efficient Friedel-Crafts alkylation processes feature low catalyst loading, broad functional group compatibilities, and the potential to provide practical pathways for the synthesis of enantioenriched bioactive triarylmethanes. PMID:24490630

Zhuo, Ming-Hua; Jiang, Yi-Jun; Fan, Yan-Sen; Gao, Yang; Liu, Song; Zhang, Suoqin

2014-02-21

343

5-Aminolevulinic acid synthesis in Escherichia coli requires expression of hemA.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

hemA and hemM, which are 213 bp apart and divergently transcribed, were separately cloned. We found that hemA is required for 5-aminolevulinic acid (ALA) synthesis in two ALA- auxotrophs. Overexpression of hemM alone did not produce ALA. More ALA was produced by strains harboring a plasmid with both hemA and hemM than by those with hemA alone. We conclude that hemA alone is required for ALA synthesis but hemA and hemM are required for maximal ALA synthesis.

Chen, W.; Russell, C. S.; Murooka, Y.; Cosloy, S. D.

1994-01-01

344

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.

2002-01-31

345

Applications of propargyl esters of amino acids in solution-phase Peptide synthesis.  

Science.gov (United States)

Propargyl esters are employed as effective protecting groups for the carboxyl group during solution-phase peptide synthesis. The propargyl ester groups can be introduced onto free amino acids by treating them with propargyl alcohol saturated with HCl. The reaction between propargyl groups and tetrathiomolybdate is exploited to deblock the propargyl esters. The removal of the propargyl group with the neutral reagent tetrathiomolybdate ensures that most of the other protecting groups used in peptide synthesis are untouched. Both acid labile and base labile protecting groups can be removed in the presence of a propargyl ester. Amino acids protected as propargyl esters are employed to synthesize di- to tetrapeptides in solution-phase demonstrating the possible synthetic utilities of the methodology. The methodology described here could be a valuable addition to currently available strategies for peptide synthesis. PMID:21760822

Ramapanicker, Ramesh; Gupta, Rohit; Megha, Rajendran; Chandrasekaran, Srinivasan

2011-01-01

346

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

347

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

348

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

349

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

350

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.

351

Synthesis of (2,3-[sup 13]C[sub 2]) erucic acid  

Energy Technology Data Exchange (ETDEWEB)

The synthesis of ([sup 13]C) erucic acid, for use in metabolic studies, is reported. The synthesis employs a repeated 3 step reaction sequence using [sup 13]C labeled triethylphosphonoacetate to extend C[sub 18:1], oleyl alcohol, by 4 carbons. The ([sup 13]C) erucic acid, obtained by hydrolysis with alcoholic KOH, gave [sup 13]C NMR signals of [delta] 24.6 and 34.1 ppm for C-3 and C-2 respectively with a J = 34.9 Hz. The overall yield was 5.5%. (author).

Olsen, J.A.; Bukata, P.A. (Wabash Coll., Crawfordsville, IN (United States). Dept. of Chemistry)

1993-10-01

352

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

353

Palladium-Catalyzed Multicomponent Synthesis of 2-Imidazolines from Imines and Acid Chlorides  

Directory of Open Access Journals (Sweden)

Full Text Available We describe the palladium-catalyzed multicomponent synthesis of 2-imidazolines. This reaction proceeds via the coupling of imines, acid chlorides and carbon monoxide to form imidazolinium carboxylates, followed by a decarboxylation. Decarboxylation in CHCl3 is found to result in a mixture of imidazolinium and imidazolium salts. However, the addition of benzoic acid suppresses aromatization, and generates the trans-disubstituted imidazolines in good yield. Combining this reaction with subsequent nitrogen deprotection provides an overall synthesis of imidazolines from multiple available building blocks.

Boran Xu

2012-11-01

354

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

355

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...

2007-01-01

356

Absence of unsaturated fatty acid synthesis in murine T lymphocytes.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Stearic acid is toxic for T lymphocytes in vitro but has little effect on B lymphocytes. To investigate the molecular basis for this difference, purified murine T and B lymphocytes were compared for their abilities to incorporate and metabolize stearic acid. Unstimulated T and B cells incorporated identical amounts of stearic acid into six different phospholipids and four neutral lipids. After mitogen stimulation, fatty acid uptake was increased in both lymphocyte types, but cell-specific dif...

Buttke, T. M.; Cleave, S.; Steelman, L.; Mccubrey, J. A.

1989-01-01

357

Effects of Acid on Synthesis of Mesoporous Titania  

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The mesoporous titania was prepared via Sol-Gel process from Ti(n-C4H9O)4(TBOT) without surfactant templates. Using sulfuric acid or acetic acid as acidity regulator, the TBOT was hydrolyzed in an acidic system, and then its hydrolysate was treated by hydrothermal method. The products were characterized by XRD, N2 adsorption-desorption isotherm and TG-DSC. The results indicate that mesoporous TiO2 can be synthesized thro...

He Jing-ping, Zhang Zhao

2009-01-01

358

Chemo-Enzymatic Synthesis of Each Enantiomer of Orthogonally-Protected 4,4-Difluoroglutamic Acid – A Candidate Monomer for Chiral Brønsted-Acid Peptide-Based Catalysts  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We have accomplished an asymmetric synthesis of each enantiomer of 4,4-difluoroglutamic acid. This ?-amino acid has been of interest in medicinal chemistry circles. Key features of the synthesis include highly scalable procedures, a Reformatsky-based coupling reaction, and straightforward functional group manipulations to make the parent amino acid. Enantioenrichment derives from an enzymatic resolution of the synthetic material. Conversion of the optically enriched compounds to orthogonally...

Li, Yang; Miller, Scott J.

2011-01-01

359

The synthesis of astaxanthin esters, independent of the formation of cysts, highly correlates with the synthesis of fatty acids in Haematococcus pluvialis.  

Science.gov (United States)

The compositions and contents of astaxanthin esters and fatty acids in four types of Haematococcus pluvialis cells were studied by HPLC and GC-MS. Results showed that the synthesis and accumulation of astaxanthin was independent of the formation of cysts, but was highly correlated with the synthesis and accumulation of fatty acids, though it is an well known phenomenon that the accumulation of astaxanthin is usually accompanied by the formation of cyst. The red cysts contain more than 30% of fatty acids, with 81% of the unsaturated fatty acids. Taken together, besides a resource of astaxanthin, H. pluvialis would be a good resource of valuable fatty acids. PMID:19093083

Miao, FengPing; Lu, Da Yan; Zhang, ChengWu; Zuo, JinCheng; Geng, YaHong; Hu, HongJun; Li, YeGuang

2008-12-01

360

A Convenient Synthesis of Amino Acid Methyl Esters  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A series of amino acid methyl ester hydrochlorides were prepared in good toexcellent yields by the room temperature reaction of amino acids with methanol in thepresence of trimethylchlorosilane. This method is not only compatible with natural aminoacids, but also with other aromatic and aliphatic amino acids.

Jiabo Li; Yaowu Sha

2008-01-01

 
 
 
 
361

High transepidermal water loss induces fatty acid synthesis and cutaneous fatty acid-binding protein expression in rat skin.  

Science.gov (United States)

Stratum corneum lipids (SCLs) are responsible for the water barrier function (WBF) of the skin in mammals. Recent studies have indicated that epidermal lipid synthesis might be regulated by WBF of stratum corneum and that cutaneous fatty acid-binding protein (C-FABP) plays an important role in fatty acid metabolism in epidermis. To clarify the regulatory mechanism of lipid synthesis, we assessed the effects of barrier disruption induced by either acetone treatment or linoleic acid deficiency on epidermal lipid synthesis in rat. Transepidermal water loss (TEWL) was measured with an evaporimeter before and after treatment. The time course of re-establishing SCLs was examined biochemically and histochemically and the expression of C-FABP in the epidermis was immunohistochemically examined. When the rat skin was covered with a vapor-impermeable membrane after the acetone treatment removing SCLs and inducing WBF disruption, the usual recovery of SCLs was blocked and TEWL was kept high by 24 h. In the uncovered area, rapid redeposition of SCLs within 24 h was found and associated with normal compositions of epidermal lipids including sphingolipids, free fatty acids and sterol and, immunohistochemically, C-FABP was very weakly expressed in epidermis at 0.5 and 2 h, and then strongly in the whole layers at 4 h, and returned to a normal pattern by 8 h. The epidermis of the covered rat skin was kept weak in C-FABP expression by 24 h. In the linoleic acid-deficient rats, TEWL did not increase and the expression pattern of C-FABP showed no notable change until 28 weeks after initiation of the diets, indicating that C-FABP expression may not be affected by altered essential fatty acid metabolism. These results suggest that increase of TEWL itself stimulates C-FABP expression, leading to activation of fatty acid metabolism. PMID:9697049

Yamaguchi, H; Yamamoto, A; Watanabe, R; Uchiyama, N; Fujii, H; Ono, T; Ito, M

1998-07-01

362

Roles of insulin and amino acids in the regulation of protein synthesis in the neonate.  

Science.gov (United States)

Neonates deposit protein at a very high rate and efficiently utilize dietary amino acids for protein deposition. This high efficiency is associated with an elevated stimulation of tissue protein synthesis by feeding. Our recent studies have focused on identification of the factors that mediate this response in the neonate. A positive curvilinear relationship between skeletal muscle protein synthesis and plasma insulin concentration was identified in fasted and fed suckling pigs; the relationship changes with development. To test the specific effects of insulin on protein metabolism in the neonate, a procedure to clamp amino acids, under hyperinsulinemic conditions, was developed. By using this technique, we showed that insulin-stimulated whole-body amino acid disposal is elevated in the neonate, and this response may account for the efficient use of dietary amino acids for protein accretion. More recent studies suggest that the enhanced stimulation of skeletal muscle protein synthesis by feeding in the neonate is primarily insulin mediated; however, the stimulation of liver protein synthesis by feeding seems to be largely a function of amino acid concentration. PMID:9478022

Davis, T A; Burrin, D G; Fiorotto, M L; Reeds, P J; Jahoor, F

1998-02-01

363

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

1986-05-01

364

Amino Acid Starvation Has Opposite Effects on Mitochondrial and Cytosolic Protein Synthesis  

Science.gov (United States)

Amino acids are essential for cell growth and proliferation for they can serve as precursors of protein synthesis, be remodelled for nucleotide and fat biosynthesis, or be burnt as fuel. Mitochondria are energy producing organelles that additionally play a central role in amino acid homeostasis. One might expect mitochondrial metabolism to be geared towards the production and preservation of amino acids when cells are deprived of an exogenous supply. On the contrary, we find that human cells respond to amino acid starvation by upregulating the amino acid-consuming processes of respiration, protein synthesis, and amino acid catabolism in the mitochondria. The increased utilization of these nutrients in the organelle is not driven primarily by energy demand, as it occurs when glucose is plentiful. Instead it is proposed that the changes in the mitochondrial metabolism complement the repression of cytosolic protein synthesis to restrict cell growth and proliferation when amino acids are limiting. Therefore, stimulating mitochondrial function might offer a means of inhibiting nutrient-demanding anabolism that drives cellular proliferation.

Pearce, Sarah F.; Rorbach, Joanna; He, Jiuya; Brea-Calvo, Gloria; Minczuk, Michal; Reyes, Aurelio; Holt, Ian J.; Spinazzola, Antonella

2014-01-01

365

Chemical Synthesis Pharmaceutical Wastewater Containing Sulfadiazine (SD and Ketoprofen(KP Treatment by Acid Separating  

Directory of Open Access Journals (Sweden)

Full Text Available Containing sulfadiazine (SD and ketoprofen (KP on the synthesis of pharmaceutical wastewater has a stronger effect on treatment of microbes. It is not used to be dealt with by wastewater treatment. This study shows that acid separation can improve bio-chemistry catabolism of the synthesis of pharmaceutical wastewater clearly. The acid separation to increase the biodegradability of waste water is conducive to aerobic and anaerobic bacteria domesticated, screened and compound treatment. Aerobic and anaerobic wastewater treatment can be done well after acid separated. Analysis of experimentation has proved that COD (chemical oxygen demand of original wastewater falls below 150 mg·L-1 from 2 52 5 mg·L-1, at last reaches to 145 mg·L-1 finally. The total removal rate of COD is about 94%. According to test it can be gotten that acid separation of the best conditions is :pH=2, acid sparating process time is 40 minut. Tests show that pretreatment of acid separation to high concentration of chemical synthesis is the key to pharmaceutical wastewater which is done by aerobic and anaerobic bacteria after acid separation.

CHEN Xi

2009-06-01

366

Síntese de glicoaminoácidos de interesse biológico Synthesis of glycosyl-amino acids of biological interest  

Directory of Open Access Journals (Sweden)

Full Text Available This work describes the synthesis of the glycosylated amino acids ?GlcNAc-Thr, ?GlcNAc-Thr and ?LacNAc-Thr by the glycosylation reaction of the amino acid threonine with the corresponding glycosyl donors ?GlcNAcCl and ?LacN3Cl. The glycosylated amino acids containing the sugar units ?-D-GlcNAc and ?-D-LacNAc O-linked to threonine amino acids are related to O-glycans found in mucins of the parasite Trypanosoma cruzi, while the corresponding ?-D-GlcNAc isomer is involved in cellular signaling events.

Vanessa Leiria Campo

2008-01-01

367

The Use of Ascorbate as an Oxidation Inhibitor in Prebiotic Amino Acid Synthesis: A Cautionary Note  

Science.gov (United States)

It is generally thought that the terrestrial atmosphere at the time of the origin of life was CO2-rich and that organic compounds such as amino acids would not have been efficiently formed abiotically under such conditions. It has been pointed out, however, that the previously reported low yields of amino acids may have been partially due to oxidation by nitrite/nitrate during acid hydrolysis. Specifically, the yield of amino acids was found to have increased significantly (by a factor of several hundred) after acid hydrolysis with ascorbic acid as an oxidation inhibitor. However, it has not been shown that CO2 was the carbon source for the formation of the amino acids detected after acid hydrolysis with ascorbic acid. We therefore reinvestigated the prebiotic synthesis of amino acids in a CO2-rich atmosphere using an isotope labeling experiment. Herein, we report that ascorbic acid does not behave as an appropriate oxidation inhibitor, because it contributes amino acid contaminants as a consequence of its reactions with the nitrogen containing species and formic acid produced during the spark discharge experiment. Thus, amino acids are not efficiently formed from a CO2-rich atmosphere under the conditions studied.

Kuwahara, Hideharu; Eto, Midori; Kawamoto, Yukinori; Kurihara, Hironari; Kaneko, Takeo; Obayashi, Yumiko; Kobayashi, Kensei

2012-12-01

368

Inhibitory effects of gentamicin and ethacrynic acid on mammalian microsomal protein synthesis.  

Science.gov (United States)

The ototoxic antibiotic gentamicin, and the ototoxic diuretic ethacrynic acid, both produce inhibitory effects on protein synthesis in microsomes isolated from rat brain. Inhibitory effects appear to be essentially independent of each other. The inhibitory dose-response curve for gentamicin is logarithmic, while that for ethacrynic acid is linear. The dose-response curves make gentamicin the predominant inhibitor when the drugs are combined at low concentrations and ethacrynic acid the predominant inhibitor when the drugs are combined at high concentrations. Accumulation of aminoglycoside by tissues of the inner ear may result in inhibition of protein synthesis in spite of low and transient plasma levels of the drug. Further inhibition of translation by ethacrynic acid could account, in part, for the ototoxic interaction of aminoglycosides and high ceiling diuretics. PMID:3972753

Buss, W C; Kauten, R; Piatt, M K

1985-01-01

369

Increased Production of Fatty Acids and Triglycerides in Aspergillus oryzae by Enhancing Expressions of Fatty Acid Synthesis-Related Genes  

Energy Technology Data Exchange (ETDEWEB)

Microbial production of fats and oils is being developedas a means of converting biomass to biofuels. Here we investigate enhancing expression of enzymes involved in the production of fatty acids and triglycerides as a means to increase production of these compounds in Aspergillusoryzae. Examination of the A.oryzaegenome demonstrates that it contains twofatty acid synthases and several other genes that are predicted to be part of this biosynthetic pathway. We enhancedthe expressionof fatty acid synthesis-related genes by replacing their promoters with thepromoter fromthe constitutively highly expressedgene tef1. We demonstrate that by simply increasing the expression of the fatty acid synthasegenes we successfullyincreasedtheproduction of fatty acids and triglyceridesby more than two fold. Enhancement of expression of the fatty acid pathway genes ATP-citrate lyase and palmitoyl-ACP thioesteraseincreasedproductivity to a lesser extent.Increasing expression ofacetyl-CoA carboxylase caused no detectable change in fatty acid levels. Increases in message level for each gene were monitored usingquantitative real-time RT-PCR. Our data demonstrates that a simple increase in the abundance of fatty acid synthase genes can increase the detectable amount of fatty acids.

Tamano, Koichi; Bruno, Kenneth S.; Karagiosis, Sue A.; Culley, David E.; Deng, Shuang; Collett, James R.; Umemura, Myco; Koike, Hideaki; Baker, Scott E.; Machida, Masa

2013-01-01

370

THE SYNTHESIS OF SALICYLATE PROMPTED BY BR0NSTED ACIDIC IONIC LIQUIDS  

Directory of Open Access Journals (Sweden)

Full Text Available Brønsted acidic ionic liquids based on imidazolium cation were employed as a series of efficient and environmentally benign catalysts and solvents for the synthesis of salicylate, the yields could reach 76%-96%. The optimal reaction conditions were determined. The results showed that Brønsted acidic ionic liquids were efficient catalysts and solvents which could be recycled easily without obvious decline in catalytic activities.

DONG JIANG

2009-01-01

371

THE SYNTHESIS OF SALICYLATE PROMPTED BY BR0NSTED ACIDIC IONIC LIQUIDS  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: English Abstract in english Brønsted acidic ionic liquids based on imidazolium cation were employed as a series of efficient and environmentally benign catalysts and solvents for the synthesis of salicylate, the yields could reach 76%-96%. The optimal reaction conditions were determined. The results showed that Brønsted acidic [...] ionic liquids were efficient catalysts and solvents which could be recycled easily without obvious decline in catalytic activities.

JIANG, DONG; LIU, JIE; YUAN WANG, YUAN; DAI, LI YI.

372

Synthesis and Pro-Apoptotic Activity of Novel Glycyrrhetinic Acid Derivatives  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Triterpenoids are used for medicinal purposes in many countries. Some, such as oleanolic and glycyrrhetinic acids, are known to be anti-inflammatory and anticarcinogenic. However, the biological activities of these naturally occurring molecules against their particular targets are weak, so the synthesis of new synthetic analogues with enhanced potency is needed. By combining modifications to both the A and C rings of 18?H-glycyrrhetinic acid, the novel synthetic derivative methyl 2-cyano-3,1...

2011-01-01

373

5'to 3' nucleic acid synthesis using 3'-photoremovable protecting group  

Energy Technology Data Exchange (ETDEWEB)

The present invention relates, in general, to a method of synthesizing a nucleic acid, and, in particular, to a method of effecting 5' to 3' nucleic acid synthesis. The method can be used to prepare arrays of oligomers bound to a support via their 5' end. The invention also relates to a method of effecting mutation analysis using such arrays. The invention further relates to compounds and compositions suitable for use in such methods.

Pirrung, Michael C. (Houston, TX); Shuey, Steven W. (Durham, NC); Bradley, Jean-Claude (Durham, NC)

1999-01-01

374

Palladium-Catalyzed Multicomponent Synthesis of 2-Imidazolines from Imines and Acid Chlorides  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We describe the palladium-catalyzed multicomponent synthesis of 2-imidazolines. This reaction proceeds via the coupling of imines, acid chlorides and carbon monoxide to form imidazolinium carboxylates, followed by a decarboxylation. Decarboxylation in CHCl3 is found to result in a mixture of imidazolinium and imidazolium salts. However, the addition of benzoic acid suppresses aromatization, and generates the trans-disubstituted imidazolines in good yield. Combining this reaction with subseque...

Boran Xu; Kraig Worrall; Arndtsen, Bruce A.

2012-01-01

375

Endosymbiotic Actinidic Archaeal Synthesis of Bile Acids from Cholesterol Regulates Cellular Function  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Aims and Objectives: Endomyocardial fibrosis along with the root wilt disease of coconut is endemic to Kerala with its radioactive actinide beach sands. Actinides like rutile as well as organisms like phytoplasmas and viroids have been implicated in the etiology of these diseases. Bile acids has been related to the pathogenesis of schizophrenia, malignancy, metabolic syndrome x, autoimmune disease and neuronal degeneration. The possibility of endogenous bile acid synthesis by actinid...

Ravikumar Kurup A.; Parameswara Achutha Kurup

2012-01-01

376

Synthesis and Quantitative Structure-Property Relationships of Side Chain-Modified Hyodeoxycholic Acid Derivatives  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Paola Sabbatini; Paolo Filipponi; Roccaldo Sardella; Benedetto Natalini; Roberto Nuti; Antonio Macchiarulo; Roberto Pellicciari; Antimo Gioiello

2013-01-01

377

Synthesis, discovery, and quantitation of Dihomo-Isofurans : Biomarkers for In Vivo Adrenic Acid Peroxidation  

DEFF Research Database (Denmark)

The growing importance of lipidomics, and the interest of non-enzymatic metabolites of polyunsaturated fatty acids (PUFAs) prompted us to initiate the synthesis of novel dihomo-IsoF compounds. Such metabolites of adrenic acid, the main PUFA in white matter, were synthesized using a divergent approach based on an orthoester cyclization. LC-MS/MS investigation on pig brains showed the potential of this novel biomarker for the first time, as a powerful new tool for brain lipid peroxidation assessment.

de La Torre, Aurélien; Lee, Yiu Yiu

2014-01-01

378

Editing of errors in selection of amino acids for protein synthesis.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

All living cells must conduct protein synthesis with a high degree of accuracy maintained in the transmission and flow of information from gene to finished protein product. One crucial "quality control" point in maintaining a high level of accuracy is the selectivity by which aminoacyl-tRNA synthetases furnish correctly activated amino acids, attached to tRNA species, as the building blocks for growing protein chains. During selection of amino acids, synthetases very often have to distinguish...

Jakubowski, H.; Goldman, E.

1992-01-01

379

Design, Synthesis, and Biological Evaluation of Potent Dual Agonists of Nuclear and Membrane Bile Acid Receptors  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Bile acids exert genomic and nongenomic effects by interacting with membrane G-protein-coupled receptors, including the bile acid receptor GP-BAR1, and nuclear receptors, such as the farnesoid X receptor (FXR). These receptors regulate overlapping metabolic functions; thus, GP-BAR1/FXR dual agonists, by enhancing the biological response, represent an innovative strategy for the treatment of enteroendocrine disorders. Here, we report the design, total synthesis, and in vitro/in vivo pharmacolo...

2014-01-01

380

Synthesis and pharmacological evaluation of cyclodextrin conjugate prodrug of mefenamic acid  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In the present investigation mefenamic acid prodrug of ?-cyclodextrins was synthesized. The primary hydroxy group of ?-cyclodextrins was used to block the acid group. The synthesis involved a series of protection and deprotection reaction. The ester was evaluated for stability in simulated gastric and intestinal fluid. The hydrolysis of cyclodextrin conjugate in colon is confirmed by the hydrolysis kinetics studies in rat faecal material. The ester was also evaluated for ulcerogenic...

2007-01-01

 
 
 
 
381

Synthesis of 14C-labeled halogen substituted indole-3-acetic acids  

International Nuclear Information System (INIS)

A general method for microscale synthesis of 14C-labeled indole-3-acetic acids with halogen substitutions in the benzene ring is described. The method utilizes halogen substituted phenylhydrazines reacted with [14C]-2-oxoglutarate to generate the halogenated indole-3-acetic acid. 3-Chlorophenyl-hydrazine yielded a mixture of the 4 and 6 chloro compounds that was resolved by C18-reverse phase high performance liquid chromatography. (author)

1985-01-01

382

Effects of Acid on Synthesis of Mesoporous Titania  

Directory of Open Access Journals (Sweden)

Full Text Available The mesoporous titania was prepared via Sol-Gel process from Ti(n-C4H9O4(TBOT without surfactant templates. Using sulfuric acid or acetic acid as acidity regulator, the TBOT was hydrolyzed in an acidic system, and then its hydrolysate was treated by hydrothermal method. The products were characterized by XRD, N2 adsorption-desorption isotherm and TG-DSC. The results indicate that mesoporous TiO2 can be synthesized through selecting acid, controlling acid concentration and supplementing TEA which can reduce the hydrolysis rate of TBOT. The mesoporous TiO2, prepared with the mole ratio of H2SO4/TBOT/TEA£½1/1/1, shows a surface area of 176m2/g, pore volume of 0.222cm3/g, mean pore size of 5nm, and narrow pore size distribution, and its thermal stability is excellent.ª¤

HE Jing-Ping,ZHANG Zhao,SHEN Jun,ZHANG Yu-Ting,CHEN Yao-Han

2009-01-01

383

Retinoic acid synthesis and functions in early embryonic development  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 expressi...

2012-01-01

384

Retinoic acid synthesis and functions in early embryonic development  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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,...

2012-01-01

385

Photochemical Synthesis of the Bioconjugate Folic Acid-Gold Nanoparticles  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

2013-01-01

386

Methylamine synthesis over solid acid catalysts: Microcalorimetric and infrared spectroscopic studies of adsorbed species  

Energy Technology Data Exchange (ETDEWEB)

Microcalorimetry was used to determine the differential enthalpy changes of adsorption versus coverage on H-ZSM-5 and H-mordenite of reactants and products of methylamine synthesis. The enthalpy changes of adsorption of dimethylether, ammonia, monomethylamine, and dimethylamine on Bronsted acid sites vary linearly from -90 to -250 kJ/mol with the gaseous proton affinities of these basic molecules. The enthalpy changes of adsorption of water and methanol vary from -60 to -90 kJ/mol. In situ infrared spectroscopy indicates that methoxyl species are present on the catalyst in flowing methanol at temperatures near 600 K; however, adsorbed ammonia and methylamines are associated with the Bronsted acid sites in gas mixtures of methanol and ammonia typically used for methylamine synthesis at these temperatures. These results suggest that dimethylether formation from methanol may occur through surface methoxyl species, while methylamine synthesis most likely involves adsorbed ammonium cations. 41 refs., 10 figs., 1 tab.

Chen, D.T.; Zhang, L.; Dumesic, J.A. (Univ. of Wisconsin, Madison (United States)); Chen Yi (Nanjing Univ. (China))

1994-03-01

387

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

2013-04-01

388

Efficient Microwave-Assisted Synthesis of Ionic Esterified Amino Acids  

Directory of Open Access Journals (Sweden)

Full Text Available In this work, an efficient microwave-assisted methodology for the esterification of unprotected ?-amino acids is described. Ionic esterified amino acids were synthesized in satisfactory yields in a facile one-pot solventless protocol from unprotected amino acids and alcohols under acid catalysis (MsOH or p-TsOH to afford the pure products after a simple work-up procedure. This procedure can also be extended to the preparation of long and short chain alkyl and benzyl esters.

Frisia Cuellar

2011-10-01

389

Synthesis of hyper branched polyol from palm oil oleic acid  

International Nuclear Information System (INIS)

Hyper branched polyol from oleic acid of palm oil has been synthesized by a two-step reaction. Dipentaerythritol was initially reacted with 2, 2-bis (hydroxymethyl) propionic acid in a solution medium aided by p-toluene sulfonic acid as a catalyst. This mixture was then used as core and reacted with the oleic acid. Optimization parameters such as processing temperature and reaction time, and chemical analysis (for example OHV, AV, FTIR, NMR and GPC) of the macromolecule synthesized is presented in this paper. (author)

2010-10-12

390

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

391

Synthesis of medium-chain fatty acids and their incorporation into triacylglycerols by cell-free fractions from Cuphea embryos.  

Science.gov (United States)

During their rapid maturation period, seeds of Cuphea wrightii A. Gray mainly accumulate medium-chain fatty acids (C8 to C14) in their storage lipids. The rate of lipid deposition (40-50 mg·d(-1)·(g fresh weight)(-1)) is fourfold higher than in seeds of Cuphea racemosa (L. f.) Spreng, which accumulate long-chain fatty acids (C16 to C18). Measurements of the key enzymes of fatty-acid synthesis in cell-free extracts of seeds of different maturities from Cuphea wrightii show that malonyl-CoA synthesis may be a triggering factor for the observed high capacity for fatty-acid synthesis. Experiments on the incorporation of [1-(14)C]acetate into fatty acids by purified plastid preparations from embryos of Cuphea wrightii have demonstrated that the biosynthesis of medium-chain fatty acids (C8 to C14) is localized in the plastid. Thus, in the presence of cofactors for lipid synthesis (ATP, NADPH, NADH, acyl carrier protein, and sn-glycerol-3-phosphate), purified plastid fractions predominantly synthesized free fatty acids, 30% of which were of medium chain length. Transesterification of the freshly synthesized fatty acids to coenzyme A and recombination with the microsomal fraction of the embryo homogenate induced triacylglycerol synthesis. It also stimulated fatty-acid synthesis by a factor 2-3 and increased the relative amount of medium-chain fatty acids bound to triacylglycerols, which corresponded to about 60-80% in this lipid fraction. PMID:24202026

Deerberg, S; von Twickel, J; Förster, H H; Cole, T; Fuhrmann, J; Heise, K P

1990-02-01

392

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.

393

Polymers from fatty acids: poly(?-hydroxyl tetradecanoic acid) synthesis and physico-mechanical studies.  

Science.gov (United States)

This Article describes the synthesis and physicomechanical properties of bioplastics prepared from methyl ?-hydroxytetradecanoic acid (Me-?-OHC14), a new monomer available by a fermentation process using an engineered Candida tropicalis strain. Melt-condensation experiments were conducted using titanium tetraisopropoxide (Ti[OiPr](4)) as a catalyst in a two-stage polymerization (2 h at 200 °C under N(2), 4 h at 220 °C under 0.1 mmHg). Poly(?-hydroxytetradecanoate), P(?-OHC14), M(w), determined by SEC-MALLS, increased from 53K to 110K as the Ti(OiPr)(4) concentration increased from 50 to 300 ppm. By varying the polymerization conditions (catalyst concentration, reaction time, second-stage reaction temperature) a series of P(?-OHC14) samples were prepared with M(w) values from 53K to 140K. The synthesized polyesters with M(w) ranging from 53K to 140K were subjected to characterization by DSC, TGA, DMTA, and tensile testing. Influences of P(?-OHC14) molecular weight, melting point, and enthalpies of melting/crystallization on material tensile properties were explored. Cold-drawing tensile tests at room temperature for P(?-OHC14) with M(w) 53K-78K showed a brittle-to-ductile transition. In contrast, P(?-OHC14) with M(w) 53K undergoes brittle fracture. Increasing P(?-OHC14) M(w) above 78K resulted in a strain-hardening phenomena and tough properties with elongation at break ~700% and true tensile strength of ~50 MPa. Comparisons between high density polyethylene and P(?-OHC14) mechanical and thermal properties as a function of their respective molecular weights are discussed. PMID:21793591

Liu, Chen; Liu, Fei; Cai, Jiali; Xie, Wenchun; Long, Timothy E; Turner, S Richard; Lyons, Alan; Gross, Richard A

2011-09-12

394

Synthesis of Hydroxynaphthyl-Substituted alpha-Amino Acid Derivatives via a Modified Mannich Reaction  

Digital Repository Infrastructure Vision for European Research (DRIVER)

An efficient one-pot synthesis of hydroxynaphthyl-substituted glycine derivatives from 2- or 1-naphthol, glyoxylic acid, and benzyl carbamate via a modified Mannich reaction is described. The enantiomers were successfully separated on analytical and semipreparative HPLC columns. Their absolute configurations were determined by CD analysis supported by TDDFT CD calculations

Csu?to?rto?ki, Rena?ta; Szatma?ri, Istva?n; Ma?ndi, Attila; Kurta?n, Tibor; Fu?lo?p, Ferenc; Mándi Attila (1981-) (vegyész, német szakfordító); Kurtán Tibor (1973-) (vegyész, angol-magyar szakfordító)

2011-01-01

395

Synthesis of sterically hindered N-acylated amino acids from N-carboxyanhydrides.  

Science.gov (United States)

Sterically hindered N-acyl, gem-disubstituted amino acids are easily prepared via the addition of organometallic reagents to N-carboxyanhydrides (NCA). The process tolerates a wide variety of functional groups and allows the synthesis of amide products not readily accessible by traditional acylation chemistry. The existence of an isocyanate intermediate was established by in situ IR spectroscopy. PMID:24571309

Schäfer, Gabriel; Bode, Jeffrey W

2014-03-01

396

Synthesis of Fluorenones through Rhodium-Catalyzed Intramolecular Acylation of Biarylcarboxylic Acids.  

Science.gov (United States)

An efficient approach to the synthesis of fluorenones via the rhodium-catalyzed intramolecular acylation of biarylcarboxylic acids was developed. Using this procedure, fluorenones with various substituents can be synthesized in good to high yields. This work marks the first recorded use of catalytic intramolecular acylation to synthesize fluorenones. PMID:24911197

Fukuyama, Takahide; Maetani, Shinji; Miyagawa, Kazusa; Ryu, Ilhyong

2014-06-20

397

Process for Synthesis of alpha , omega -Alkanediphosphonic Acids (Triphenyl Phosphite; Trischloroalkyl Phosphite).  

Science.gov (United States)

Process for synthesis of alpha , omega -alkanediphosphonic acids is characterized by the fact that triphenyl phosphite and trischloroalkyl phosphite in a mole ratio of 2:1 are heated to temperatures of 210 to 300 exp 0 C, preferably 220 to 280 exp 0 C, an...

K. Sommer

1983-01-01

398

Essential role of ELOVL4 protein in very long chain fatty acid synthesis and retinal function.  

Science.gov (United States)

Very long chain polyunsaturated fatty acid (VLC-PUFA)-containing glycerophospholipids are highly enriched in the retina; however, details regarding the specific synthesis and function of these highly unusual retinal glycerophospholipids are lacking. Elongation of very long chain fatty acids-4 (ELOVL4) has been identified as a fatty acid elongase protein involved in the synthesis of VLC-PUFAs. Mutations in ELOVL4 have also been implicated in an autosomal dominant form of Stargardt disease (STGD3), a type of juvenile macular degeneration. We have generated photoreceptor-specific conditional knock-out mice and used high performance liquid chromatography-mass spectrometry (HPLC-MS) to examine and analyze the fatty acid composition of retinal membrane glycerophosphatidylcholine and glycerophosphatidylethanolamine species. We also used immunofluorescent staining and histology coupled with electrophysiological data to assess retinal morphology and visual response. The conditional knock-out mice showed a significant decrease in retinal glycerophospholipids containing VLC-PUFAs, specifically contained in the sn-1 position of glycerophosphatidylcholine, implicating the role of Elovl4 in their synthesis. Conditional knock-out mice were also found to have abnormal accumulation of lipid droplets and lipofuscin-like granules while demonstrating photoreceptor-specific abnormalities in visual response, indicating the critical role of Elovl4 for proper rod or cone photoreceptor function. Altogether, this study demonstrates the essential role of ELOVL4 in VLC-PUFA synthesis and retinal function. PMID:22199362

Harkewicz, Richard; Du, Hongjun; Tong, Zongzhong; Alkuraya, Hisham; Bedell, Matthew; Sun, Woong; Wang, Xiaolei; Hsu, Yuan-Hao; Esteve-Rudd, Julian; Hughes, Guy; Su, Zhiguang; Zhang, Ming; Lopes, Vanda S; Molday, Robert S; Williams, David S; Dennis, Edward A; Zhang, Kang

2012-03-30

399

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

400

Oxidative cross-coupling of allenyl ketones and organoboronic acids: expeditious synthesis of highly substituted furans.  

Science.gov (United States)

Allenyl ketones are employed as coupling partners in palladium-catalyzed oxidative cross-coupling reactions with organoboronic acids. This reaction constitutes an efficient methodology for the synthesis of highly substituted furan derivatives. Palladium-carbene migratory insertion is proposed as the key step in this transformation. PMID:24615951

Xia, Ying; Xia, Yamu; Ge, Rui; Liu, Zhen; Xiao, Qing; Zhang, Yan; Wang, Jianbo

2014-04-01

 
 
 
 
401

Silica supported phosphomolybdic acid: an efficient heterogeneous catalyst for Friedlander synthesis of quinolines.  

Science.gov (United States)

Silica supported phosphomolybdic acid, an eco-friendly heterogeneous catalyst, has been found to be highly efficient for Friedlander synthesis of quinolines in excellent yields. A variety of ketones afford the quinolines smoothly. The catalyst can be easily recovered and reused. PMID:18591832

Das, Biswanath; Krishnaiah, Martha; Laxminarayana, Keetha; Nandankumar, Duddukuri

2008-07-01

402

Hypervalent iodine mediated synthesis of C-2 deoxy glycosides and amino Acid glycoconjugates.  

Science.gov (United States)

A simple, efficient, and practical method for the synthesis of C-2 deoxy-2-iodo glycoconjugates in self-assembled structures was found using PhI(OCOR)2. 2-Iodo glycoserinyl esters were intramolecularly converted into 2-iodo serinyl glycosides which upon dehalogenation gave C-2 deoxy amino acid glycoconjugates. PMID:24754460

Islam, Maidul; Tirukoti, Nishanth D; Nandi, Shyamapada; Hotha, Srinivas

2014-05-16

403

One-pot synthesis of heterostructured Pt-Ru nanocrystals for catalytic formic acid oxidation.  

Science.gov (United States)

We demonstrate the synthesis of monodisperse, heterostructured Pt-Ru nanocrystals with a novel core-shell structure by a one-step method. The Pt-Ru nanocrystals show excellent electrocatalytic activity towards formic acid oxidation. Such core-shell structured Pt-Ru nanocrystals are potential candidates as anode catalysts in fuel cells. PMID:21225027

Lu, Yizhong; Chen, Wei

2011-03-01

404

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

405

The Solid-Phase Synthesis of PolyglutamateSS OF Folic Acid.  

Science.gov (United States)

Details of an unambiguous chemical synthesis by which pteroyl-(gamma-L-glutamyl)n-L-glutamic acid of any desired chain length (up to n = 6) may be prepared are reported. The procedures employed are modifications of the Merrifield solid-phase peptide synth...

C. L. Krumdieck C. M. Baugh

1968-01-01

406

Epoxy Resin and Polyurethane Compositions from Glycolized Poly (ethylene terephthalate Wastes  

Directory of Open Access Journals (Sweden)

Full Text Available The possibility to use poly(ethylene terephthalate (PET bottles production waste as raw material for compositions with high adhesion ability has been investigated. PET waste was glycolyzed with polypropylene glycol and three kinds of oligoesters were formed after depolymerization reaction. The polydispersity of product formed was 1.05. The possibilities to use PET glycolysis products – oligoesters for epoxy resin and polyurethanes were studied. Two-step reaction of oligoesters with epichlorohydrin was chosen for epoxy resin synthesis, while glycolyzed PET reaction with aliphatic isocyanate was used for polyurethane synthesis. The structure and properties of the obtained polymers were investigated. DOI: http://dx.doi.org/10.5755/j01.ms.19.3.5237

Gintaras MACIJAUSKAS

2013-09-01

407

76 FR 22867 - Polyethylene Terephthalate Film, Sheet, and Strip From the United Arab Emirates: Final Results of...  

Science.gov (United States)

...Administration [A-520-803] Polyethylene Terephthalate Film, Sheet, and Strip...antidumping duty order on polyethylene terephthalate film (PET Film) from...have taken place. See Polyethylene Terephthalate Film, Sheet, and...

2011-04-25

408

78 FR 52500 - 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...Int'l Trade 2013); Polyethylene Terephthalate Film, Sheet, and...

2013-08-23

409

76 FR 1135 - Polyethylene Terephthalate Film, Sheet, and Strip From the Republic of Korea: Final Results 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...

2011-01-07

410

76 FR 12938 - Polyethylene Terephthalate Film, Sheet and Strip From India: Extension of Time Limit for Final...  

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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...

2011-03-09

411

77 FR 20357 - Polyethylene Terephthalate Film, Sheet, and Strip From the United Arab Emirates: Final Results of...  

Science.gov (United States)

...Administration [A-520-803] Polyethylene Terephthalate Film, Sheet, and Strip...antidumping duty order on polyethylene terephthalate film (PET Film) from...1\\ See Polyethylene Terephthalate Film, Sheet, and...

2012-04-04

412

75 FR 70901 - Polyethylene Terephthalate Film, Sheet, and Strip From the Republic of Korea: Final Results of...  

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

2010-11-19

413

76 FR 12937 - Polyethylene Terephthalate Film, Sheet and Strip From India: Extension of Time Limit for Final...  

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...

2011-03-09

414

78 FR 29700 - Polyethylene Terephthalate Film, Sheet, and Strip From the United Arab Emirates: Final Results of...  

Science.gov (United States)

...Administration [A-520-803] Polyethylene Terephthalate Film, Sheet, and Strip...antidumping duty order on polyethylene terephthalate film (PET Film) from...1\\ See Polyethylene Terephthalate Film, Sheet, and...

2013-05-21

415

78 FR 14266 - Polyethylene Terephthalate Film, Sheet, and Strip From Taiwan: Notice of Correction to the Final...  

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...

2013-03-05

416

Bis(2-amino-4-methylpyridinium terephthalate tetrahydrate  

Directory of Open Access Journals (Sweden)

Full Text Available In the crystal structure of the title salt, 2C6H9N2+·C8H4O42?·4H2O, the terephthalate carboxylate groups interacts with the 2-amino-4-methylpyridinium cations via a pair of N—H...O hydrogen bonds, forming an R22(8 ring motif. The water molecules form an R66(12 ring motif through O—H...O hydrogen bonds and these motifs are fused, forming a supramolecular chain along the c axis. The R22(8 and R66(12 ring motifs are connected via O—H...O hydrogen bonds. In addition, ?–? stacking interactions are observed between the pyridinium rings [centroid–centroid distance = 3.522?(12?Å].

Madhukar Hemamalini

2010-08-01

417

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...

418

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...

419

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

420

Function of Heterologous Mycobacterium tuberculosis InhA, a Type 2 Fatty Acid Synthase Enzyme Involved in Extending C20 Fatty Acids to C60-to-C90 Mycolic Acids, during De Novo Lipoic Acid Synthesis in Saccharomyces cerevisiae?  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We describe the physiological function of heterologously expressed Mycobacterium tuberculosis InhA during de novo lipoic acid synthesis in yeast (Saccharomyces cerevisiae) mitochondria. InhA, representing 2-trans-enoyl-acyl carrier protein reductase and the target for the front-line antituberculous drug isoniazid, is involved in the activity of dissociative type 2 fatty acid synthase (FASII) that extends associative type 1 fatty acid synthase (FASI)-derived C20 fatty acids to form C60-to-C90 ...

2008-01-01

 
 
 
 
421

Glutathione deficiency increases hepatic ascorbic acid synthesis in adult mice.  

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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...

1992-01-01

422

Synthesis and properties of poly 5-methylthiouridylic acid.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In an effort to search for good methods for the enzymatic synthesis of polynucleotide analogs with antitemplate activity, 5-methylthiouridine-5'-diphosphate (ms5UDP) has been synthesized and investigated as a substrate for polynucleotide phosphorylase. While ms5UDP was polymerized at a very low rate to give a 6% yield of polynucleotides by the polynucleotide phosphorylase of Micrococcus luteus, it was utilized more efficiently by the corresponding enzyme of Escherichia coli resulting in a 15%...

Ho, Y. K.

1984-01-01

423

Efficient synthesis of fluorothiosparfosic acid analogues with potential antitumoral activity.  

Science.gov (United States)

In this paper, we describe a short synthesis of N-(phosphonoacetyl)-L-aspartate (PALA) analogues. The mono- and difluorinated thioacetamide precursors were prepared in one step from methyl (diethoxyphosphono)di- and monofluoromethyldithioacetates 8 and 11 as starting materials. Antiproliferating properties on a L1210 strain and ATCase inhibition of these new compounds are disclosed. ThioPALA(FF) 5c showed a remarkable cytotoxic activity towards murine leukemia L1210, when used as tetraester. PMID:15975800

Pfund, Emmanuel; Lequeux, Thierry; Masson, Serge; Vazeux, Michel; Cordi, Alex; Pierre, Alain; Serre, Valérie; Hervé, Guy

2005-08-15

424

Bispidine Derivatives : Synthesis and Interactions with Lewis Acids  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this thesis, the improved synthesis and investigations into the properties of some 3,7-diazabicyclo[3.3.1]nonane (bispidine) derivatives are described. These compounds are structurally related to the naturally occurring lupanine alkaloids, they are of interest because of their cardiac antiarrhythmic function as well as their use as bases or ligands in organic chemical reactions. Their chemical properties are related to the presence of a rigid molecular scaffold with two nitrogen atoms that...

Toom, Lauri

2006-01-01

425

Synthesis of quinoxalines in the presence of heteropoly acids  

Directory of Open Access Journals (Sweden)

Full Text Available Efficient synthesis of quinoxaline derivatives from the reaction of ?-diketones and o-phenylenediamines in the presence of Keggin-type heteropolyacids (HPA such as H3PMo12O40, H4SiW12O40, K7PMo2W9O40, H3PW12O40.SiO2 and H3PW12O40 in high yields and short reaction times, and at room temperature is introduced.

Fatemeh Hakimia

2013-04-01

426

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

427

Synthesis of acid-base bifunctional mesoporous materials by oxidation and thermolysis  

International Nuclear Information System (INIS)

Graphical abstract: A novel and efficient method has been developed for the synthesis of acid-base bifunctional catalyst. The obtained sample of SO3H-MCM-41-NH2 containing amine and sulfonic acids exhibits excellent catalytic activity in aldol condensation reaction. Research highlights: ? Synthesize acid-base bifunctional mesoporous materials SO3H-MCM-41-NH2. ? Oxidation and then thermolysis to generate acidic site and basic site. ? Exhibit good catalytic performance in aldol condensation reaction between acetone and various aldehydes. -- Abstract: A novel and efficient method has been developed for the synthesis of acid-base bifunctional catalyst SO3H-MCM-41-NH2. This method was achieved by co-condensation of tetraethylorthosilicate (TEOS), 3-mercaptopropyltrimethoxysilane (MPTMS) and (3-triethoxysilylpropyl) carbamicacid-1-methylcyclohexylester (3TAME) in the presence of cetyltrimethylammonium bromide (CTAB), followed by oxidation and then thermolysis to generate acidic site and basic site. X-ray diffraction (XRD) and transmission electron micrographs (TEM) show that the resultant materials keep mesoporous structure. Thermogravimetric analysis (TGA), X-ray photoelectron spectra (XPS), back titration, solid-state 13C CP/MAS NMR and solid-state 29Si MAS NMR confirm that the organosiloxanes were condensed as a part of the silica framework. The bifunctional sample (SO3H-MCM-41-NH2) containing amine and sulfonic acids exhibits excellent acid-basic properties, which make it possess high activity in aldol condensation reaction between acetone and various aldehydes.

2011-06-01

428

Hydrolysis, absorption and metabolism of di(2-ethylhexyl) terephthalate in the rat.  

Science.gov (United States)

1. The hydrolysis of di(2-ethylhexyl) terephthalate (DEHT) and di(2-ethylhexyl) phthalate (DEHP) were studied using rat gut homogenate fractions in vitro. Both isomers were hydrolysed by the intestinal fraction; however, DEHP was hydrolysed to 2-ethylhexanol (2-EH) and mono(2-ethylhexyl) phthalate (MEHP) in about equal proportions, whereas DEHT was hydrolysed to 2-EH and terephthalic acid (TPA). The half-lives for disappearance of the diesters were determined to be 12.6 min for DEHP and 53.3 min for DEHT. 2. The absorption and metabolism of DEHT were studied by administering [hexyl-2-14C]DEHT (in corn oil) by oral gavage at a dose level of 100 mg/kg to 10 adult male Sprague-Dawley rats. Urine, faeces and expired air were collected for 144 h and analysed for the presence of radioactivity, and faeces and urine were analysed for unlabelled metabolites. 3. Radioactivity was eliminated in faeces (56.5 +/- 12.1% of dose) primarily as unchanged DEHT, small amounts of MEHT and polar metabolites; excreted in urine (31.9 +/- 10.9% of dose) principally as MEHT and metabolic products of 2-EH; and expired as 14CO2 (3.6 +/- 0.9% of dose). Less than 2% of the administered radioactivity was found in the carcass. Small amounts of 14C were found in the tissues with the highest amounts found in liver and fat. 4. Metabolites identified in urine included terephthalic acid (equivalent to 51% of dose), oxidized metabolites of 2-EH and MEHT, and glucuronic and sulphuric acid conjugates (equivalent to about 10% of dose).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8079503

Barber, E D; Fox, J A; Giordano, C J

1994-05-01

429

Synthesis, biological distribution and radiation dosimetry of Te-123m analogues of hexadecenoic acid  

International Nuclear Information System (INIS)

The synthesis and biological distribution of four Te-123m analogues of hexadecenoic acid in rats, rabbits and dogs were described for use as possible myocardial imaging agents. The heart-to-blood ratios ranged from 0.13 for 3-telluranonadecenoic acid in rats at 5 mins to 6.25 for 18-methyl-17-tellura-9-nonadecenoic acid in dogs at 24 hrs. The biological half-life of the Te-123m labelled fatty acids ranged from 26 to 583 hrs in the hearts of the test animals. These Te-123m fatty acids were retained in the heart longer than radioiodinated fatty acids and have acceptable absorbed doses to the various target organs. (U.K.)

1982-01-01

430

Thermoelastic Expansion and Creep of Polyethylene Terephthalate and Polypyromelitimide Film and Polyethylene Terephthalate Fibers from 20 to 295K.  

Science.gov (United States)

A quartz tube dilatometer was used to measure the lineal thermal expansion and creep of single lengths of polyethylene terephthalate (PETP) film, polypyromelitimide (PPMI) film, and PETP multifiber yarn, while stressed under constant tension. Tensions bel...

P. M. McConnel D. E. Daney J. B. Kirgis

1970-01-01

431

Chemical modification and functionalisation of poly(ethylene terephthalate) fiber  

Energy Technology Data Exchange (ETDEWEB)

Poly(ethylene terephthalate ) (PET) fibers were modified by deep UV irradiation which was produced by a low pressure mercury lamp. FT-IR and XPS analyses were used to elucidate the surface chemical composition of PET fibers treated with UV. Relative O{sub 1s} intensity increased considerably and it was found that oxygen was incorporated in the form of COO on the fiber surface. FT-IR and XPS analyses proved the existence of carboxylic groups on the surfaces and the adsorption test of cationic compound further supported these results. The concentration of carboxylic acid group on the surface increased remarkably with increasing irradiation time. XPS analysis and adsorption experiments proved that the surface structure of the UV{sub i}rradiated PET fibers were stable for 12 months. Antibacterial property and the deodorization rate of UV-irradiated PET fibers adsorbed with the berberine compound were investigated. reduction rates of bacteria increased by about 21 to 99% compared to unradiated PET fiber. Deodorization rates of 23% for unradiated PET fiber increased to about 75% for 30 min irradiated samples. (author). 33 refs., 3 tabs., 11 figs.

Kim, I.H.; Kim, S.H. [Sungkyunkwan University, Suwon (Korea)

2002-05-01

432

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

2010-03-01

433

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

434

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

2003-11-01

435

Double-helical nucleic acids with cross-linked strands: synthesis and applications in molecular biology  

International Nuclear Information System (INIS)

Data on the methods employed for cross-linking of DNA strands and for the synthesis of oligonucleotide duplexes with cross-links between strands are summarised. Existing methods are systematised; their advantages and drawbacks are discussed. The examples of applications of DNA duplexes with covalently cross-linked chains for the study of protein-nucleic acid recognition and mechanisms of action of nucleic acid-binding proteins for gaining information about the spatial structure of nucleic acids, and for the solution of other problems of molecular biology are given. The bibliography includes 131 references.

1998-03-31

436

Synthesis and pharmacological evaluation of cyclodextrin conjugate prodrug of mefenamic acid  

Directory of Open Access Journals (Sweden)

Full Text Available In the present investigation mefenamic acid prodrug of ?-cyclodextrins was synthesized. The primary hydroxy group of ?-cyclodextrins was used to block the acid group. The synthesis involved a series of protection and deprotection reaction. The ester was evaluated for stability in simulated gastric and intestinal fluid. The hydrolysis of cyclodextrin conjugate in colon is confirmed by the hydrolysis kinetics studies in rat faecal material. The ester was also evaluated for ulcerogenicity. Results of these studies established the primary aim of masking the ulcerogenic potential of free drug, by using 12-fold dose of the normal dose of mefenamic acid and equivalent doses of the ester.

Dev S

2007-01-01

437

Stereocontrolled synthesis of syn-?-Hydroxy-?-amino acids by direct aldolization of pseudoephenamine glycinamide.  

Science.gov (United States)

?-Hydroxy-?-amino acids figure prominently as chiral building blocks in chemical synthesis and serve as precursors to numerous important medicines. Reported herein is a method for the synthesis of ?-hydroxy-?-amino acid derivatives by aldolization of pseudoephenamine glycinamide, which can be prepared from pseudoephenamine in a one-flask protocol. Enolization of (R,R)- or (S,S)-pseudoephenamine glycinamide with lithium hexamethyldisilazide in the presence of LiCl followed by addition of an aldehyde or ketone substrate affords aldol addition products that are stereochemically homologous with L- or D-threonine, respectively. These products, which are typically solids, can be obtained in stereoisomerically pure form in yields of 55-98?%, and are readily transformed into ?-hydroxy-?-amino acids by mild hydrolysis or into 2-amino-1,3-diols by reduction with sodium borohydride. This new chemistry greatly facilitates the construction of novel antibiotics of several different classes. PMID:24692320

Seiple, Ian B; Mercer, Jaron A M; Sussman, Robin J; Zhang, Ziyang; Myers, Andrew G

2014-04-25

438

Determination of potential migrants from commercial amber polyethylene terephthalate bottle wall  

Energy Technology Data Exchange (ETDEWEB)

Potential migrants were isolated from commercial polyethylene terephthalate (PET) bottles using Soxhlet extraction. The concentrated extract was then subjected to GC/MS analysis. A total of 19 migrants has been identified. The majority of compounds appeared to be intermediate reaction products or residual monomers of their dehydration and transesterification products. Several processing aids such as fatty acids and commonly used plasticizers were also identified. The amount of seven compounds present in the major portion of exhaustive extract of the PET bottle wall ranged from 800 micrograms/g polymer to as low as 0.6 microgram/g.

Kim, H.; Gilbert, S.G.; Johnson, J.B. (Rutgers Univ., New Brunswick, NJ (USA))

1990-02-01

439

5-Aminolevulinic acid stimulation of porphyrin and hemoglobin synthesis by uninduced Friend erythroleukemic cells.  

Science.gov (United States)

Porphyrin synthesis and iron accumulation was stimulated by exogenous 5-aminolevulinic acid (ALA) in uninduced Friend erythroleukemic cells (FELC). Uroporphyrin and protoporphyrin were the major intermediated precursors produced. All porphyrin types were conjugated to protein insoluble cellular components and could be extracted only by methanol sulfuric acid esterification. Heme content of the uninduced FELC was increased 6-fold in the presence of 5 x 10(-4) M ALA. As a consequence, the synthesis of the minor murine hemoglobin component was preferentially induced, an effect similar to that expressed by exogenous hemin. Addition of exogenous ALA to 0.5% DMSO-induced cells increased total hemoglobin synthesis with a higher efficiency of the minor hemoglobin. The endogenous synthesis of porphyrin from exogenous ALA was markedly reduced by hemin. Uroporphyrin, coproporphyrin, protoporphyrin and heme were equally repressed, indicating an inhibitory effect of hemin on ALA dehydrase and urosynthetase activities. In addition, hemin repressed [3H]leucine incorporation into protein by uninduced cells. Incubation of uninduced cells in culture medium without serum in the presence of hemin blocked their protein synthesis activity, whereas addition of serum exerted a protective effect on living FELC. PMID:288514

Malik, Z; Djaldetti, M

1979-06-01

440

Short-term regulation of fatty acid synthesis in isolated alveolar type II cells from adult rat lung. Effects of free fatty acids and hormones  

Energy Technology Data Exchange (ETDEWEB)

The total rate of fatty acid synthesis in alveolar type II cells freshly isolated from the lungs of adult rats was measured. The rate of incorporation of /sup 3/H from /sup 3/H2O into cellular fatty acids was linear during 3-hr incubations and was very brisk (18 ng-atoms /sup 3/H/10(6) cells/hr +/- 2 (mean +/- SD, n . 23)). When the nutrient medium (Minimum Essential Medium) was supplemented with various hormones or free fatty acids, the long-chain fatty acids (C/sub 14/-C/sub 20/) caused a decrease in the rate of /sup 3/H incorporation to a variable degree depending on the species of fatty acid. Stearate (10(-4) M) and palmitate (10(-4) M) caused the greatest inhibition of de novo cellular fatty acid synthesis, followed by myristate, arachidonate, and oleate. Insulin (10(-7) M), glucagon (10(-8) M), terbutaline (10(-5) M), 8-bromo-cyclic AMP (10(-3) M), the essential fatty acid linoleate (10(-4) M), and the medium-chain-free fatty acids laurate and octanoate (10(-4) M) did not alter the rate of fatty acid synthesis in type II cells. We demonstrated that the alveolar type II cell is a major lipogenic cell type in the rat. We also demonstrated that the availability of preformed fatty acids in the extracellular milieu is one factor regulating the rate of fatty acid synthesis in these cells.

Geppert, E.F.; Elstein, K.H.

1983-05-01