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Sample records for acid isomers present

  1. Determination of the D and L isomers of some protein amino acids present in soils

    NASA Technical Reports Server (NTRS)

    Pollock, G. E.; Cheng, C.-N.; Cronin, S. E.

    1977-01-01

    The D and L isomers of some protein amino acids present in soils were measured by using a gas chromatographic technique. The results of two processing procedures were compared to determine the better method. Results of the comparison indicated that the determination of D and L percentages requires amino acid purification if one is to obtain accurate data. It was found that very significant amounts of D-alanine, D-aspartic acid, and D-glutamic acid were present in the contemporary soils studied. Valine, isoleucine, leucine, proline, and phenylalanine generally contained only a trace to very small amounts of the D isomer. It is probable that the D-amino acids from the alanine, aspartic, and glutamic acids are contributed to the soil primarily via microorganisms. The finding of very significant quantities of some D-amino acids (about 5-16%) in present-day soils may alert some investigators of geological sediments to a possible problem in using amino acid racemization as an age-dating technique.

  2. Structure, dynamics, and energetics of lysobisphosphatidic acid (LBPA) isomers.

    PubMed

    Goursot, A; Mineva, T; Bissig, C; Gruenberg, J; Salahub, D R

    2010-12-01

    Lysobisphosphatidic acid (LBPA), or bis(monoacylglycerol)phosphate, is a very interesting lipid, that is mainly found in late endosomes. It has several intriguing characteristics, which differ from those of other animal glycerophospholipids, that may be related to its specific functions, particularly in the metabolism of cholesterol. Its phosphodiester group is bonded at the sn-1 (sn-1') positions of the glycerols rather than at sn-3 (sn-3'); the position of the two fatty acid chains is still under debate but, increasingly, arguments favor the sn-2, sn-2' position in the native molecule, whereas isolation procedures or acidic conditions lead to the thermodynamically more stable sn-3, sn-3' structure. Because of these peculiar features, it can be expected that LBPA shape and interactions with membrane lipids and proteins are related to its structure at the molecular level. We applied quantum mechanical methods to study the structures and stabilities of the 2,2' and 3,3' LBPA isomers, using a step-by-step procedure from glycerol to precursors (in vitro syntheses) and to the final isoforms. The structures of the two positional LBPA isomers are substantially different, showing that the binding positions of the fatty acid chains on the glycerol backbone determine the shape of the LBPA molecule and thus, possibly, its functions. The 3,3' LBPA structures obtained are more stable with respect to the 2,2' form, as expected from experiment. If one argues that the in vivo synthesis starts from the present glycerol conformers and considering the most stable bis(glycero)phosphate structures, the 2,2' isoform should be the most probable isomer. PMID:21053942

  3. Conjugated Linoleic Acids and Inflammation: Isomer and Tissue Specific Responses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Conjugated linoleic acids (CLAs) are a series of geometric and positional isomers of linoleic acid that have been studied for their effects against diabetes, cancer, and atherosclerosis, all conditions with an inflammatory component. Despite the continued interest in CLA, there are many controversi...

  4. Anaerobic biodegradability of phthalic acid isomers and related compounds.

    PubMed

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

    1999-02-01

    All three phthalic acid isomers (ortho, meta and para benzene dicarboxylic acid) are produced in massive amounts, and used in the chemical industry as plasticizers or for the production of polyester. Wastestreams generated during the production of phthalate isomers generally contain high concentrations of aromatic acids. To study the potential biodegradability of these primarily anthropogenic compounds in anaerobic bioreactors, biodegradability studies were performed. Compounds tested were benzoate, ortho-phthalate, isophthalate, terephthalate, dimethyl phthalate, dimethyl terephthalate, para-toluate and para-xylene. Seed materials tested were two types of granular sludge and digested sewage sludge. It was found that all phthalate isomers and their corresponding dimethyl-esters, could be completely mineralized by all seed materials studied. Lag phases required for 50% degradation of these compounds, ranged from 17 to 156 days. The observed degradation curves could be explained by growth of an initially small amount of organisms in the inoculum with the specific ability to degrade one phthalate isomer. The observed order in the length of the lag phases for the phthalate isomers is: phthalate < terephthalate < isophthalate. This order appears to be related to the environmental abundancy of the different phthalate isomers. The initial step in the degradation pathway of both dimethyl phthalate esters was hydrolysis of the ester sidechain, resulting in the formation of the corresponding mono-methyl-phthalate isomer and phthalate isomer. The rate limiting step in mineralization of both dimethyl phthalate and dimethyl terephthalate was found to be fermentation of the phthalate isomer. Para-toluate was degraded only by digested sewage sludge after a lag phase of 425 days. The observed degradation rates of this compound were very low. No mineralization of para-xylene was observed. In general, the differences in the lag phases between different seed materials were relatively

  5. Lipase-catalyzed fractionation of conjugated linoleic acid isomers.

    PubMed

    Haas, M J; Kramer, J K; McNeill, G; Scott, K; Foglia, T A; Sehat, N; Fritsche, J; Mossoba, M M; Yurawecz, M P

    1999-09-01

    The abilities of lipases produced by the fungus Geotrichum candidum to selectively fractionate mixtures of conjugated linoleic acid (CLA) isomers during esterification of mixed CLA free fatty acids and during hydrolysis of mixed CLA methyl esters were examined. The enzymes were highly selective for cis-9,trans-11-18:2. A commercial CLA methyl ester preparation, containing at least 12 species representing four positional CLA isomers, was incubated in aqueous solution with either a commercial G. candidum lipase preparation (Amano GC-4) or lipase produced from a cloned high-selectivity G. candidum lipase B gene. In both instances selective hydrolysis of the cis-9,trans-11-18:2 methyl ester occurred, with negligible hydrolysis of other CLA isomers. The content of cis-9, trans-11-18:2 in the resulting free fatty acid fraction was between 94 (lipase B reaction) and 77% (GC-4 reaction). The commercial CLA mixture contained only trace amounts of trans-9,cis-11-18:2, and there was no evidence that this isomer was hydrolyzed by the enzyme. Analogous results were obtained with these enzymes in the esterification in organic solvent of a commercial preparation of CLA free fatty acids containing at least 12 CLA isomers. In this case, G. candidum lipase B generated a methyl ester fraction that contained >98% cis-9,trans-11-18:2. Geotrichum candidum lipases B and GC-4 also demonstrated high selectivity in the esterification of CLA with ethanol, generating ethyl ester fractions containing 96 and 80%, respectively, of the cis-9,trans-11 isomer. In a second set of experiments, CLA synthesized from pure linoleic acid, composed essentially of two isomers, cis-9,trans-11 and trans-10,cis-12, was utilized. This was subjected to esterification with octanol in an aqueous reaction system using Amano GC-4 lipase as catalyst. The resulting ester fraction contained up to 97% of the cis-9,trans-11 isomer. After adjustment of the reaction conditions, a concentration of 85% trans-10,cis-12

  6. The Immunomodulatory Activity of Jacaric Acid, a Conjugated Linolenic Acid Isomer, on Murine Peritoneal Macrophages

    PubMed Central

    Liu, Wai Nam; Leung, Kwok Nam

    2015-01-01

    This study aims at demonstrating the immunomodulatory property of jacaric acid, a conjugated linolenic acid (CLNA) isomer that is present in jacaranda seed oil, on murine peritoneal macrophages. Our results showed that jacaric acid exhibited no significant cytotoxicity on the thioglycollate-elicited murine peritoneal macrophages as revealed by the neutral red uptake assay, but markedly increased their cytostatic activity on the T-cell lymphoma MBL-2 cells as measured by the fluorometric CyQuant® NF Cell Proliferation Assay Kit. Flow cytometric analysis indicated that jacaric acid could enhance the endocytic activity of macrophages and elevated their intracellular production of superoxide anion. Moreover, jacaric acid-treated macrophages showed an increase in the production of nitric oxide which was accompanied by an increase in the expression level of inducible nitric oxide synthase protein. In addition, the secretion of several pro-inflammatory cytokines, including interferon-γ, interleukin-1β and tumor necrosis factor-α, was up-regulated. Collectively, our results indicated that the naturally-occurring CLNA isomer, jacaric acid, could exhibit immunomodulating activity on the murine peritoneal macrophages in vitro, suggesting that this CLNA isomer may act as an immunopotentiator which can be exploited for the treatment of some immunological disorders with minimal toxicity and fewer side effects. PMID:26629697

  7. Hydroxybenzoic acid isomers and the cardiovascular system

    PubMed Central

    2014-01-01

    Today we are beginning to understand how phytochemicals can influence metabolism, cellular signaling and gene expression. The hydroxybenzoic acids are related to salicylic acid and salicin, the first compounds isolated that have a pharmacological activity. In this review we examine how a number of hydroxyphenolics have the potential to ameliorate cardiovascular problems related to aging such as hypertension, atherosclerosis and dyslipidemia. The compounds focused upon include 2,3-dihydroxybenzoic acid (Pyrocatechuic acid), 2,5-dihydroxybenzoic acid (Gentisic acid), 3,4-dihydroxybenzoic acid (Protocatechuic acid), 3,5-dihydroxybenzoic acid (α-Resorcylic acid) and 3-monohydroxybenzoic acid. The latter two compounds activate the hydroxycarboxylic acid receptors with a consequence there is a reduction in adipocyte lipolysis with potential improvements of blood lipid profiles. Several of the other compounds can activate the Nrf2 signaling pathway that increases the expression of antioxidant enzymes, thereby decreasing oxidative stress and associated problems such as endothelial dysfunction that leads to hypertension as well as decreasing generalized inflammation that can lead to problems such as atherosclerosis. It has been known for many years that increased consumption of fruits and vegetables promotes health. We are beginning to understand how specific phytochemicals are responsible for such therapeutic effects. Hippocrates’ dictum of ‘Let food be your medicine and medicine your food’ can now be experimentally tested and the results of such experiments will enhance the ability of nutritionists to devise specific health-promoting diets. PMID:24943896

  8. Analysis of eicosapentaenoic and docosahexaenoic acid geometrical isomers formed during fish oil deodorization.

    PubMed

    Fournier, Véronique; Juanéda, Pierre; Destaillats, Frédéric; Dionisi, Fabiola; Lambelet, Pierre; Sébédio, Jean-Louis; Berdeaux, Olivier

    2006-09-29

    Addition of long-chain polyunsaturated fatty acids (LC-PUFAs) from marine oil into food products implies preliminary refining procedures of the oil which thermal process affects the integrity of LC-PUFAs. Deodorization, the major step involving high temperatures, is a common process used for the refining of edible fats and oils. The present study evaluates the effect of deodorization temperature on the formation of LC-PUFA geometrical isomers. Chemically isomerized eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were used as reference samples. Fish oil samples have been deodorized at 180, 220 and 250 degrees C for 3 h and pure EPA and DHA fatty acid methyl esters (FAMEs) were chemically isomerized using p-toluenesulfinic acid as catalyst. FAMEs prepared from fish oil were fractionated by reversed-phase high-performance liquid chromatography (RP-HPLC). Geometrical isomers produced by both processes were fractionated by silver-ion thin-layer chromatography (Ag-TLC) and silver-ion high-performance liquid chromatography (Ag-HPLC). The FAME fractions were subsequently analyzed by gas chromatography (GC) on a 100 m highly polar cyanopropylpolysiloxane coated capillary column, CP-Sil 88. Our results show that thermally induced geometrical isomerization appears to be a directed reaction and some ethylenic double bond positions on the hydrocarbon chain are more prone to stereomutation. Only minor changes were observed in the EPA and DHA trans isomers content and distribution after deodorization at 180 degrees C. The analyses of EPA and DHA isomer fractions revealed that it is possible to quantify EPA geometrical isomers by GC using the described conditions. However, we notice that a mono-trans isomer of DHA, formed during both chemical and thermal treatments, co-elute with all-cis DHA. This feature should be taken into consideration for the quantification of DHA geometrical isomers. PMID:16893549

  9. Formation of Meteoritic Amino Acids: Isovaline and its Isomers

    NASA Astrophysics Data System (ADS)

    Hudson, Reggie; Moore, Marla; Dworkin, Jason

    It has been known for several decades that amino acids, and other complex organics, are found in meteorites. In particular, Murchison (CM) samples contain over seventy amino acids, these being identified by high-level chromatographic methods. Among Murchison's amino acids, isovaline stands out as being both non-biological (non-protein) and having a relatively high abundance. While approximately equal amounts of D- and L- isovaline have been reported in Murchison and other CM meteorites, this molecule's structure appears to prohibit its racemization in aqueous solutions. We recently have investigated the low-temperature solid-phase chemistry of both isovaline and valine with an eye toward each molecule's formation, stability, and possible interconversions of their D and L enantiomers. Ion-irradiated isovalineand valine-containing ices were examined by IR spectroscopy and highly-sensitive liquid chromatography/time-of-flight mass spectral methods to assess both amino-acid destruction and racemization. Samples were studied in the presence and in the absence of water-ice, and the destruction of both isovaline and valine was measured as a function of radiation dose. In addition, we have synthesized isovaline, valine, and their amino acid isomers by solid-phase radiation-chemical pathways other than the oft-invoked Strecker process. This presentation will review and summarize some of our recent findings and place them in a context of related work. - Our work has been supported by a grant to the Goddard Center for Astrobiology through the NASA Astrobiology Institute. Experiments were performed in the Cosmic Ice Laboratory (RLH, MHM) and the Astrobiology Analytical Laboratory (JPD) at the NASA Goddard Space Flight Center.

  10. Differential intestinal absorption of two fatty acid isomers: Elaidic and oleic acids

    SciTech Connect

    Bernard, A.; Echinard, B.; Carlier, H. )

    1987-12-01

    The absorption of {sup 14}C-labeled oleic acid and {sup 14}C-labeled elaidic acid was studied in bile- and pancreatic juice-diverted adult rats. In some cases these acids were compared with {sup 14}C-labeled palmitic acid absorption. Sodium taurocholate-emulsified test infusates containing an equimolar mixture of monopalmitin and two fatty acids (oleic and elaidic or palmitic), one of which was {sup 14}C labeled, were infused through a duodenal canula. The chyle was collected from the mesenteric lymphatic vessel by plastic tubing. Among the three fatty acids studied, oleic acid exhibited the highest lymphatic recovery rate. Elaidic and palmitic acids appeared more slowly and in lesser amounts. Simultaneously, the highest amount of chylomicrons was observed when the lipid emulsion contained oleic acid alone; the lowest was observed when elaidic acid was the only unsaturated fatty acid. Experimental data have also shown that compared with elaidic acid, oleic acid is preferentially incorporated into the lymph triglycerides. The authors conclude from the data presented that the enterocytic enzymes involved in the absorption of lipids show a high degree of specificity related to the fatty acid isomery, since the absorption of elaidic acid differs markedly from its isomer oleic acid.

  11. [Determination of dimethylbenzoic acid isomers in urine by gas chromatography].

    PubMed

    Kostrzewski, P; Wiaderna-Brycht, A; Czerski, B

    1994-01-01

    Trimethylobenzene (TMB) is a main ingredient of many organic solvents used in industry. In Farbasol (Polish trade name of the solvent) TMB occurs as a mixture of three isomers: pseudocumene (1, 2, 4-TMB) 30%; mesitylene (1, 3, 5-TMB) 15%; hemimellitene (1,2,3-TMB) 5%. As it is known in human organism, TMB is metabolized mainly to dimethylbenzoic (DMBA) and dimethylhippuric (DMHA) acids, and some authors suggest, that the acids excreted in urine can be biological indicators of exposure to TMB. This study was aimed at developing the method of determination of DMBA isomers in urine. Biological material was hydrolyzed with sodium hydroxide and next extracted with diethyl ether. DMBA concentration in urine was determined by gas chromatography using a variant of quantitative analysis with internal standard (5-methyl-2-isopropylphenol, thymol). Analytical parameters of the developed method of determination of DMBA isomers in urine such as linearity, precision, reproducibility, stability (192 days, when urine samples stored at-18 degrees C), detectability limit (400 micrograms/dm3) have been fully compatible with the requirements of biological monitoring. In order to confirm the presence of DMBA isomers in urine, four volunteers were exposed (8 hours) to Farbasol in toxicological chamber. The TMB concentration in the air, determined by means of gas chromatograph (HP 5890), amounted to 100 mg/m3 (MAC value in Poland). In urine samples collected 2,3-; 2,4-; 2,5-; 2,6-; 3,4-; 3,5-dimethylbenzoic acids were identified by means of GC/MSD.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8170375

  12. Fuel properties of heptadecene isomers prepared via tandem isomerization-decarboxylation of oleic acid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Heptadecene isomers were prepared via tandem isomerization-decarboxylation of oleic acid using catalytic triruthenium dodecacarbonyl [Ru3(CO)12]. Chromatographic and spectroscopic characterization of the isolated heptadecene mixture indicated that it consisted of 96% internal isomers and 4% aromatic...

  13. Are conjugated linolenic acid isomers an alternative to conjugated linoleic acid isomers in obesity prevention?

    PubMed

    Miranda, Jonatan; Arias, Noemi; Fernández-Quintela, Alfredo; del Puy Portillo, María

    2014-04-01

    Despite its benefits, conjugated linoleic acid (CLA) may cause side effects after long-term administration. Because of this and the controversial efficacy of CLA in humans, alternative biomolecules that may be used as functional ingredients have been studied in recent years. Thus, conjugated linolenic acid (CLNA) has been reported to be a potential anti-obesity molecule which may have additional positive effects related to obesity. According to the results reported in obesity, CLNA needs to be given at higher doses than CLA to be effective. However, because of the few studies conducted so far, it is still difficult to reach clear conclusions about the potential use of these CLNAs in obesity and its related changes (insulin resistance, dyslipidemia, or inflammation). PMID:24029409

  14. Preferential polymerization and adsorption of L-optical isomers of amino acids relative to D-optical isomers on kaolinite templates.

    NASA Technical Reports Server (NTRS)

    Jackson, T. A.

    1971-01-01

    Experiments on the polymerization of the L- and D-optical isomers of aspartic acid and serine using kaolinite as a catalyst showed that the L-optical isomers were polymerized at a much higher rate than the D-optical isomers; racemic (DL-) mixtures were polymerized at an intermediate rate. The peptides formed from the L-monomers were preferentially adsorbed by the clay. In the absence of kaolinite, no significant or consistent difference in the behavior of the L- and D-optical isomers was observed. In experiments on the adsorption of L- and D-phenylalanine by kaolinite, the L-optical isomer was preferentially adsorbed.

  15. Antioxidant and anti-inflammatory effect of conjugated linolenic acid isomers against streptozotocin-induced diabetes.

    PubMed

    Saha, Siddhartha S; Ghosh, Mahua

    2012-09-28

    The present study was undertaken to evaluate the effect of α-eleostearic acid and punicic acid, two isomers of conjugated linolenic acid (CLnA) present in bitter gourd (Momordica charantia) and snake gourd oil (Trichosanthes anguina), respectively, against oxidative stress, inflammatory challenge and aberration in erythrocyte morphology due to streptozotocin (STZ)-induced diabetes. Male albino rats were divided into four groups consisting of eight animals in each group. The first group served as control and diabetes was induced in rats in groups 2-4 by a single intraperitoneal injection of STZ. Moreover, rats in groups 3 and 4 were treated with 0·5 % of α-eleostearic acid and 0·5 % of punicic acid of the total lipid given, respectively, by oral administration once per d. After administration, CLnA isomers had significantly reduced oxidative stress, lipid peroxidation and restored antioxidant and pro-inflammatory enzymes such as superoxide dismutase, catalase, and glutathione peroxidase, reduced glutathione, NO synthase level in pancreas, blood and erythrocyte lysate. The ferric reducing antioxidant power (FRAP) assay of plasma showed that CLnA treatment caused improvement in the FRAP value which was altered after STZ treatment due to an increased level of free radicals. Expression of inflammatory cytokines such as TNF-α and IL-6 in blood and expression of hepatic NF-κB (p65) increased significantly after STZ treatment due to increased inflammation which was restored with the administration of CLnA isomers. From the obtained results, it could be concluded that α-eleostearic acid and punicic acid showed potent antioxidant and anti-inflammatory activity with varying effectivity. PMID:22182422

  16. Fuel properties of heptadecene isomers prepared via tandem isomerization-decarboxylation of oleic acid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Heptadecene isomers were prepared via tandem isomerization-decarboxylation of oleic acid using catalytic triruthenium dodecacarbonyl [Ru3(CO)12]. Chromatographic and spectroscopic characterization of the isolated heptadecene mixture indicated that it consisted of 96% internal trans isomers and 4% ar...

  17. Diet supplementation with the cis-9,trans-11 conjugated linoleic acid isomer affects the size of adipocytes in Wistar rats.

    PubMed

    Lopes, Paula A; Martins, Susana V; Pinho, Mário S; Alfaia, Cristina M; Fontes, Carlos M G A; Rodrigues, Pedro O; Morais, Graça S L; Castro, Matilde F; Pinto, Rui; Prates, José A M

    2008-07-01

    Previous reports have demonstrated that conjugated linoleic acid (CLA) acts on body fat accumulation in a variety of animal models. The aim of the present study was to investigate the effect of cis (c)-9,trans (t)-11 and t10,c12 CLA isomers on the number and size of adipocytes from the inguinal and retroperitoneal fats in Wistar male rats. A 5.1% palm oil-based diet was supplemented with CLA isomers as follows: 0.6% of c9,t11, 0.6% of t10,c12, 1.3% of c9,t11 and t10,c12 isomers in mixture, and a control nonsupplemented group for comparative purposes. Fat tissues were prepared on microscope slides for histologic examination using an image-analysis software to count the number of adipocytes and measure cell sizes. The results showed that CLA isomers did not affect (P > .05) either final body and fat depot weights or serum lipids (with the exception of triacylglycerols) and adipocytokines (leptin and adiponectin). Animals fed the c9,t11 CLA isomer diet showed larger adipocytes when compared to other groups. Independently of the CLA dietary treatment, retroperitoneal fat showed larger adipocytes (3319 microm(2)) and therefore a smaller number of adipocytes per unit of area, compared to inguinal fat (3055 microm(2)). Taken together, the data suggest that a palm oil-based diet supplemented with the c9,t11 CLA isomer in Wistar rats, in contrast to the t10,c12 isomer and the mixture of both isomers, increases adipocyte dimensions in inguinal and retroperitoneal fat depots, while having a minor effect in serum lipids and adipocytokines. PMID:19083449

  18. C18-unsaturated branched-chain fatty acid isomers: characterization and physical properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Iso-oleic acid is a mixture of C18-unsaturated branched-chain fatty acid isomers with a methyl group on various positions of the alkyl chain, which is the product of the skeletal isomerization reaction of oleic acid and is the intermediate used to make isostearic acid (C18-saturated branched-chain f...

  19. Separation of the isomers of benzene poly(carboxylic acid)s by quaternary ammonium salt via formation of deep eutectic solvents.

    PubMed

    Hou, Yucui; Li, Jian; Ren, Shuhang; Niu, Muge; Wu, Weize

    2014-11-26

    Because of similar properties and very low volatility, isomers of benzene poly(carboxylic acid)s (BPCAs) are very difficult to separate. In this work, we found that isomers of BPCAs could be separated efficiently by quaternary ammonium salts (QASs) via formation of deep eutectic solvents (DESs). Three kinds of QASs were used to separate the isomers of BPCAs, including the isomers of benzene tricarboxylic acids (trimellitic acid, trimesic acid, and hemimellitic acid) and the isomers of benzene dicarboxylic acids (phthalic acid and isophthalic acid). Among the QASs, tetraethylammonium chloride was found to have the best performance, which could completely separate BPCA isomers in methyl ethyl ketone solutions. It was found that the hydrogen bond forming between QAS and BPCA results in the selective separation of BPCA isomers. QAS in DES was regenerated effectively by the antisolvent method, and the regenerated QAS was reused four times with the same high efficiency. PMID:25351281

  20. In vitro interaction study of retinoic acid isomers with telmisartan and amlodipine by equilibrium dialysis method using UV spectroscopy

    NASA Astrophysics Data System (ADS)

    Varghese, Susheel John; Johny, Sojimol K.; Paul, David; Ravi, Thengungal Kochupappy

    2011-07-01

    The in vitro protein binding of retinoic acid isomers (isotretinoin and tretinoin) and the antihypertensive drugs (amlodipine and telmisartan) was studied by equilibrium dialysis method. In this study, free fraction of drugs and the % of binding of drugs in the mixture to bovine serum albumin (BSA) were calculated. The influence of retinoic acid isomers on the % of protein binding of telmisartan and amlodipine at physiological pH (7.4) and temperature (37 ± 0.5 °C) was also evaluated. The in vitro displacement interaction study of drugs telmisartan and amlodipine on retinoic acid isomers and also interaction of retinoic acid isomers on telmisartan and amlodipine were carried out.

  1. Osmoprotection by Pipecolic Acid in Sinorhizobium meliloti: Specific Effects of d and l Isomers

    PubMed Central

    Gouffi, Kamila; Bernard, Théophile; Blanco, Carlos

    2000-01-01

    dl-Pipecolic acid (dl-PIP) promotes growth restoration of Sinorhizobium meliloti cells facing inhibitory hyperosmolarity. Surprisingly, d and l isomers of this imino acid supplied separately were not effective. The uptake of l-PIP was significantly favored in the presence of the d isomer and by a hyperosmotic stress. Chromatographic analysis of the intracellular solutes showed that stressed cells did not accumulate radiolabeled l-PIP. Rather, it participates in the synthesis of the main endogenous osmolytes (glutamate and the dipeptide N-acetylglutaminylglutamine amide) during the lag phase, thus providing a means for the stressed cells to recover the osmotic balance. 13C nuclear magnetic resonance analysis was used to determine the fate of d-PIP taken into the cells. In the absence of l-PIP, the imported d isomer was readily degraded. Supplied together with its l isomer, d-PIP was accumulated temporarily and thus might contribute together with the endogenous osmolytes to enhance the internal osmotic strength. Furthermore, it started to disappear from the cytosol when the l isomer was no longer available in the culture medium (during the late exponential phase of growth). Together, these results show an uncommon mechanism of protection of osmotically stressed cells of S. meliloti. It was proved, for the first time, that the presence of the two isomers of the same molecule is necessary for it to manifest an osmoprotective activity. Indeed, d-PIP seems to play a major role in cellular osmoadaptation through both its own accumulation and improvement of the utilization of the l isomer as an immediate precursor of endogenous osmolytes. PMID:10831411

  2. Improved synthesis and characterization of saturated branched-chain fatty acid isomers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The development of viable technologies for producing green products from renewable fats and oils is highly desirable since such materials can serve as replacements for non-renewable and poorly biodegradable petroleum-based products. Mixtures of saturated branched-chain fatty acid isomers (sbc-FAs),...

  3. Methyl-branched poly(hydroxyalkanoate) biosynthesis from 13- methyltetradecanoic acid and mixed isostearic acid isomer substrates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pseudomonas resinovorans, a known medium-chain-length (mcl-) poly(hydroxyalkanoate) (PHA) producer, was grown on 13-methyltetradecanoic acid (13-MTDA) and a mixture of isostearic acid (IA) isomers to produce methyl-branched mcl-PHA polymers. Shake flask experiments revealed polymer productivities (...

  4. Screening of multicomponent crystals of L-tryptophan with three isomers of pyridinedicarboxylic acids

    NASA Astrophysics Data System (ADS)

    Das, Babulal

    2016-08-01

    Multicomponent crystallization of L-tryptophan with three different isomers of pyridinedicarboxylic acids, namely, 2,3-pyridinedicarboxylic acid (2,3-PDA), 2,5-pyridinedicarboxylic acid (2,5-PDA) and 2,6-pyridinedicarboxylic acid (2,6-PDA), were screened using conventional solution cocrystallization technique. Whereas the new phases derived from the amino acid with 2,3-PDA or 2,5-PDA were analyzed using powder X-ray diffraction and thermal analysis techniques, the crystalline phase synthesized from 2,6-substituted isomer was further characterized by single crystal X-ray diffraction. Structural analysis revealed that the amino acid exists in the zwitterionic form interacting with the neutral 2,6-PDA by strong intermolecular hydrogen bonding. The components in the co-crystal self-assemble leading to a three dimensional hydrogen bonded closed packed network structure. Isothermal calorimetric titration showed that among the three isomers, 2,6-PDA showed relatively strong binding interaction towards the amino acid in water at 298 K. All the crystals exhibit marginal quenching of fluorescence properties of L-tryptophan in the solid state.

  5. Effect of exogenous amylolytic enzymes on the accumulation of chlorogenic acid isomers in wounded potato tubers.

    PubMed

    Torres-Contreras, Ana Mariel; Nair, Vimal; Cisneros-Zevallos, Luis; Jacobo-Velázquez, Daniel A

    2014-08-01

    Potato tubers under wounding stress synthesize chlorogenic acid isomers, which are phenolic compounds that prevent chronic diseases. The biosynthesis of phenolic compounds in plants requires aromatic amino acids that are produced from sugars. Therefore, in this study, we hypothesized that the wound-induced accumulation of chlorogenic acid isomers in potatoes could be enhanced if the availability of sugars is increased by exogenous amylolytic enzymes applied to the surface of the site of wounding. To test this hypothesis, wounded potatoes stored at 20 °C were treated with amylolytic enzymes (pullulanase and amyloglucosidase, 282 units/mL, 10 mL/kg) after being stored for 0 (E0h), 48 (E48h), or 96 h (E96h). The highest level of accumulation of total chlorogenic acid isomers (∼210% higher than that of time 0 h samples) was observed after storage for 120 h for the E96h treatment. The results suggest that increasing the availability of carbon sources needed for the biosynthesis of phenolic compounds would trigger their accumulation in wounded plants. PMID:25032895

  6. Differential developmental toxicity of naphthoic acid isomers in medaka (Oryzias latipes) embryos.

    PubMed

    Carney, Michael W; Erwin, Kyle; Hardman, Ron; Yuen, Bonny; Volz, David C; Hinton, David E; Kullman, Seth W

    2008-01-01

    Polycyclic aromatic hydrocarbons (PAHs) are widespread persistent pollutants that readily undergo biotic and abiotic conversion to numerous transformation products in rivers, lakes and estuarine sediments. Here we characterize the developmental toxicity of four PAH transformation products each structural isomers of hydroxynaphthoic acid: 1H2NA, 2H1NA, 2H3NA, and 6H2NA. Medaka fish (Oryzias latipes) embryos and eleutheroembryos were used to determine toxicity. A 96-well micro-plate format was used to establish a robust, statistically significant platform for assessment of early life stages. Individual naphthoic acid isomers demonstrated a rank order of toxicity with 1H2NA>2H1NA>2H3NA>6H2NA being more toxic. Abnormalities of circulatory system were most pronounced including pericardial edema and tube heart. To determine if HNA isomers were AhR ligands, spatial-temporal expression and activity of CYP1A was measured via in vivo EROD assessments. qPCR measurement of CYP1A induction proved different between isomers dosed at respective concentrations affecting 50% of exposed individuals (EC50s). In vitro, all ANH isomers transactivated mouse AhR using a medaka CYP1A promoter specific reporter assay. Circulatory abnormalities followed P450 induction and response was consistent with PAH toxicity. A 96-well micro-plates proved suitable as exposure chambers and provided statistically sound evaluations as well as efficient toxicity screens. Our results demonstrate the use of medaka embryos for toxicity analysis thereby achieving REACH objectives for the reduction of adult animal testing in toxicity evaluations. PMID:18433798

  7. Formation of isomers of anionic hemiesters of sugars and carbonic acid in aqueous medium.

    PubMed

    Dos Santos, Vagner B; Vidal, Denis T R; Francisco, Kelliton J M; Ducati, Lucas C; do Lago, Claudimir L

    2016-06-16

    Hemiesters of carbonic acid can be freely formed in aqueous media containing HCO3(-)/CO2 and mono- or poly-hydroxy compounds. Herein, (13)C NMR spectroscopy was used to identify isomers formed in aqueous solutions of glycerol (a prototype compound) and seven carbohydrates, as well as to estimate the equilibrium constant of formation (Keq). Although both isomers are formed, glycerol 1-carbonate corresponds to 90% of the product. While fructose and ribose form an indistinct mixture of isomers, the anomers of d-glucopyranose 6-carbonate correspond to 74% of the eight isomers of glucose carbonate that were detected. The values of Keq for the disaccharides sucrose (4.3) and maltose (4.2) are about twice the values for the monosaccharides glucose (2.0) and fructose (2.3). Ribose (Keq = 0.89)-the only sugar without a significant concentration of a species containing a -CH2OH group in an aqueous solution-resulted in the smallest Keq. On the basis of the Keq value and the concentrations of HCO3(-) and glucose in blood, one can anticipate a concentration of 2-4 µmol L(-1) for glucose 6-carbonate, which corresponds to ca. of 10% of its phosphate counterpart (glucose 6-phosphate). PMID:27111726

  8. Differential effects of conjugated linoleic acid isomers on the biophysical and biochemical properties of model membranes

    PubMed Central

    Subbaiah, Papasani V.; Sircar, Debajit; Aizezi, Buzulagu; Mintzer, Evan

    2010-01-01

    Conjugated linoleic acids (CLA) are known to exert several isomer-specific biological effects, but their mechanisms of action are unclear. In order to determine whether the physicochemical effects of CLA on membranes play a role in their isomer-specific effects, we synthesized phosphatidylcholines (PCs) with 16:0 at sn-1 position and one of four CLA isomers (trans10 cis12 (A), trans9 trans11 (B), cis9 trans11 (C), and cis9 cis11 (D)) at sn-2, and determined their biophysical properties in monolayers and bilayers. The surface areas of the PCs with the two natural CLA (A and C) were similar at all pressures, but they differed significantly in presence of cholesterol, with PC-A condensing more than PC-C. Liposomes of PC-A similarly showed increased binding of cholesterol compared to PC-C liposomes. PC-A liposomes were less permeable to carboxyfluorescein compared to PC-C liposomes. The PC with two trans double bonds (B) showed the highest affinity to cholesterol and lowest permeability. The two natural CLA PCs (A and C) stimulated lecithin-cholesterol acyltransferase activity by 2-fold, whereas the unnatural CLA PCs (B and D) were inhibitory. These results suggest that the differences in the biophysical properties of CLA isomers A and C may partly contribute to the known differences in their biological effects. PMID:20004173

  9. Synthesis of phosphoramidites of isoGNA, an isomer of glycerol nucleic acid

    PubMed Central

    Kim, Keunsoo; Punna, Venkateshwarlu; Karri, Phaneendrasai

    2014-01-01

    Summary IsoGNA, an isomer of glycerol nucleic acid GNA, is a flexible (acyclic) nucleic acid with bases directly attached to its linear backbone. IsoGNA exhibits (limited) base-pairing properties which are unique compared to other known flexible nucleic acids. Herein, we report on the details of the preparation of isoGNA phosphoramidites and an alternative route for the synthesis of the adenine derivative. The synthetic improvements described here enable an easy access to isoGNA and allows for the further exploration of this structural unit in oligonucleotide chemistry thereby spurring investigations of its usefulness and applicability. PMID:25246971

  10. Distribution of trans and cis 18:1 fatty acid isomers in chicks fed different fats.

    PubMed

    al-Athari, A K; Watkins, B A

    1988-05-01

    The effects of dietary trans isomers of 18:1 (t-18:1) were studied in chicks by feeding purified diets containing soybean oil (SBO) as the control lipid source, saturated fat (SF), hydrogenated soybean oil (HSBO), or spent restaurant grease (SRG) for three weeks. Argentation thin-layer chromatography and gas-liquid chromatography were used to separate trans and cis (c) isomers of 18:1 and to determine the fatty acid composition in chick tissues. Chicks fed HSBO (34% t-18:1 of total 18:1) had weight gains similar to those of chicks fed SF but significantly (P less than .05) lower gains than those of chicks fed SBO or SRG. No differences were observed in feed conversion ratios (total feed:total gain) across treatments. Trans-18:1 was incorporated into liver, heart, lung, and abdominal fat pad of chicks fed HSBO. Chicks fed HSBO had higher levels of c-16:1 omega 7 and 18:1 and lower levels of linoleate and arachidonate in tissue lipids. Similar changes were observed in liver microsomal fatty acids of chicks fed SRG that was adequate in linoleate, but which contained low levels of t-18:1 (4% of total 18:1). Positional and geometrical isomers of 18:1 appear to impair essential fatty acid metabolism in the chick. PMID:3405954

  11. Micellar and sub-micellar ultra-high performance liquid chromatography of hydroxybenzoic acid and phthalic acid positional isomers.

    PubMed

    Fasciano, Jennifer M; Danielson, Neil D

    2016-03-18

    Micellar liquid chromatography (MLC) has been used primarily for the separation of neutral analytes of varying polarities, most commonly phenols and polyaromatic hydrocarbons, but does not seem to have been used to study aromatic hydroxy acids in detail. We have studied the separation of hydroxybenzoic acid mixtures, including monohydroxybenzoic and dihydroxybenzoic acid positional isomers by MLC. Sodium dodecylsulfate (SDS) is investigated as the modifying surfactant on a C18 ultra-high performance liquid chromatography (UHPLC) column (100×2.1mm, 1.8μm). The addition of only SDS (no organic solvent) to the mobile phase reduced the influence of hydrophobic interactions while improving the retention times, resolution, and peak shapes, even at concentrations below the critical micellization concentration (CMC). The UHPLC separation of 7 hydroxybenzoic acids, including 6 dihydroxybenzoic acid positional isomers and one trihydroxybenzoic acid, is achieved with high efficiency using 0.1% SDS in 1.84mM sulfuric acid (pH 2.43) mobile phase, in less than 6min with a flow rate of 0.3mLmin(-1), and in less than four min with a flow rate of 0.7mLmin(-1). Six monohydroxybenzoic acid isomers are also effectively separated by MLC, using a 0.5% SDS mobile phase modifier, in less than 20min with a flow rate of 0.3mLmin(-1), and in less than 14min with a flow rate of 0.7mLmin(-1). The 3 phthalic acid isomers could be separated using a similar mobile phase and flow rates in less than 6 and 4min. Solute-micelle equilibrium constants and partition coefficients are calculated for 6 monohydroxybenzoic acids based on a plot of MLC retention factor vs. mobile phase micelle concentration. All aromatic acid isomers studied can be classified as binding solutes in the MLC retention mechanism. Less effective separations are observed with shorter chain surfactants, leading to higher retention times and poor peak shapes. It is concluded that increasing chain length led to more efficient MLC

  12. Interactions between major chlorogenic acid isomers and chemical changes in coffee brew that affect antioxidant activities.

    PubMed

    Liang, Ningjian; Xue, Wei; Kennepohl, Pierre; Kitts, David D

    2016-12-15

    Coffee bean source and roasting conditions significantly (p<0.05) affected the content of chlorogenic acid (CGA) isomers, several indices of browning and subsequent antioxidant values. Principal component analysis was used to interpret the correlations between physiochemical and antioxidant parameters of coffee. CGA isomer content was positively correlated (p<0.001) to capacity of coffee to reduce nitric oxide and scavenge Frémy's salt. Indices of browning in roasted coffee were positively correlated (p<0.001) to ABTS and TEMPO radical scavenging capacity, respectively. Only the CGA content of coffee corresponded to intracellular antioxidant capacity measured in Caco-2 intestinal cells. This study concluded that the intracellular antioxidant capacity that best describes potential health benefits of coffee positively corresponds best with CGA content. PMID:27451179

  13. Site-Specific Mapping of Sialic Acid Linkage Isomers by Ion Mobility Spectrometry.

    PubMed

    Guttman, Miklos; Lee, Kelly K

    2016-05-17

    Detailed structural elucidation of protein glycosylation is a tedious process often involving several techniques. Glycomics and glycoproteomics approaches with mass spectrometry offer a rapid platform for glycan profiling but are limited by the inability to resolve isobaric species such as linkage and positional isomers. Recently, ion mobility spectrometry (IMS) has been shown to effectively resolve isobaric oligosaccharides, but the utility of IMS to obtain glycan structural information on a site-specific level with proteomic analyses has yet to be investigated. Here, we report that the addition of IMS to conventional glycoproteomics platforms adds additional information regarding glycan structure and is particularly useful for differentiation of sialic acid linkage isomers on both N- and O-linked glycopeptides. With further development IMS may hold the potential for rapid and complete structural elucidation of glycan chains at a site-specific level. PMID:27089023

  14. Differential accumulation and elimination behavior of perfluoroalkyl Acid isomers in occupational workers in a manufactory in China.

    PubMed

    Gao, Yan; Fu, Jianjie; Cao, Huiming; Wang, Yawei; Zhang, Aiqian; Liang, Yong; Wang, Thanh; Zhao, Chunyan; Jiang, Guibin

    2015-06-01

    In this study, serum and urine samples were collected from 36 occupational workers in a fluorochemical manufacturing plant in China from 2008 to 2012 to evaluate the body burden and possible elimination of linear and branched perfluoroalkyl acids (PFAAs). Indoor dust, total suspended particles (TSP), diet, and drinking water samples were also collected to trace the occupational exposure pathway to PFAA isomers. The geometric mean concentrations of perfluorooctanesulfonate (PFOS), perfluorooctanoate (PFOA), and perfluorohexanesulfonate (PFHxS) isomers in the serum were 1386, 371, and 863 ng mL(-1), respectively. The linear isomer of PFOS, PFOA, and PFHxS was the most predominant PFAA in the serum, with mean proportions of 63.3, 91.1, and 92.7% respectively, which were higher than the proportions in urine. The most important exposure routes to PFAA isomers in the occupational workers were considered to be the intake of indoor dust and TSP. A renal clearance estimation indicated that branched PFAA isomers had a higher renal clearance rate than did the corresponding linear isomers. Molecular docking modeling implied that linear PFOS (n-PFOS) had a stronger interaction with human serum albumin (HSA) than branched isomers did, which could decrease the proportion of n-PFOS in the blood of humans via the transport of HSA. PMID:25927957

  15. Cyclodextrin and its complexation for resolution of isomers using diffusion ordered spectroscopy

    NASA Astrophysics Data System (ADS)

    Chaudhari, Sachin R.; Srinivasa; Suryaprakash, N.

    2013-02-01

    Diffusion ordered spectroscopy (DOSY) generally fails to separate the peaks pertaining to isomeric species possessing identical molecular weights and similar hydrodynamic radii. The present study demonstrates the resolution of isomers using α/β-cyclodextrin as a co-solute by Matrix Assisted Diffusion Ordered Spectroscopy. The resolution of isomers has been achieved by measuring the significant differences in the diffusion rates between the positional isomers of aminobenzoic acids, benzenedicarboxylic acids and between the cis, trans isomers, fumaric acid and maleic acid.

  16. Novel characterisation of minor α-linolenic acid isomers in linseed oil by gas chromatography and covalent adduct chemical ionisation tandem mass spectrometry.

    PubMed

    Gómez-Cortés, P; Brenna, J T; Lawrence, P; de la Fuente, M A

    2016-06-01

    Discrimination between polyunsaturated fatty acid isomers with three double bonds is a great challenge, due to structural similarities and similar polarities. In this study, we report the identification of four minor geometrical isomers of α-linolenic acid (ALA) present in linseed oil samples: (9E,12Z,15E)-, (9Z,12Z,15E)-, (9Z,12E,15Z)- and (9E,12Z,15Z)-octadeca-9,12,15-trienoic acids, chromatographically resolved by gas chromatography (GC) using a new and highly polar ionic phase column (SLB-IL111). Gas chromatography-electron ionisation mass spectrometry (GC-EIMS) determined that the four unknown compounds were C18:3 n-3 isomers. The positional 9-12-15 C18:3 configuration was achieved by covalent adduct chemical ionisation tandem mass spectrometry (CACI-MS/MS) while geometrical configuration was established with analytical standards based on relative retention. We hypothesised that these isomers are formed during linseed oil deodorisation and postulate preferred and unfavoured isomerisation pathways of ALA. PMID:26830571

  17. Gene characterized for membrane desaturase that produces (E)-11 isomers of mono- and diunsaturated fatty acids.

    PubMed

    Liu, Weitian; Jiao, Hongmei; Murray, Nancy C; O'Connor, Marion; Roelofs, Wendell L

    2002-01-22

    Moth species have evolved integral membrane desaturases that exhibit a wide diversity in substrate specificity, as well as in regiospecificity and stereospecificity of the unsaturated products. We report here the cloning and expression of a single desaturase from the sex pheromone gland of the light brown apple moth, Epiphyas postvittana, that makes E11 isomers of monounsaturated (E11-16 and E11-14) fatty acids and a diunsaturated (E9,E11-14) fatty acid. In the pheromone gland, the monoene precursor is made available by beta oxidation of E11-16 acid with a subsequent two-carbon loss to E9-14 acid. A functional assay using a baculovirus expression system required addition of myristic acid and E9-14 acid precursors to demonstrate the unusual regiospecificity and stereospecificity of this desaturase. The amino acid sequence of this desaturase has approximately 61% identity to that of Z11-desaturases from two other insect species, and only approximately 48% identity to the metabolic Z9-desaturases in those species. A pheromone-gland Z9-desaturase gene also was found with the light brown apple moth that differed in its deduced amino acid sequence (66% identity) with the metabolic Z9-desaturase from fat body in this species. PMID:11805319

  18. Beef conjugated linoleic acid isomers reduce human cancer cell growth even when associated with other beef fatty acids.

    PubMed

    De La Torre, Anne; Debiton, Eric; Juanéda, Pierre; Durand, Denys; Chardigny, Jean-Michel; Barthomeuf, Chantal; Bauchart, Dominique; Gruffat, Dominique

    2006-02-01

    Although many data are available concerning anticarcinogenic effects of industrial conjugated linoleic acid (CLA), few studies have reported the antitumour properties of CLA mixtures originating from ruminant products. The aim of the present study was to investigate the in vitro antiproliferative effects of beef CLA mixtures on breast, lung, colon, melanoma and ovarian human cancer cell lines. For this purpose, four fatty acid (FA) extracts prepared from beef lipid and varying in their CLA composition, their corresponding purified CLA-enriched fractions, and mixtures of pure synthetic CLA, the composition of which reproduced that of the four selected beef samples, were tested on cancer cell lines. Cancer cells were exposed for 48 h to medium containing 100 microm-FA and their proliferation was determined by quantifying cellular DNA content (Hoechst 33342 dye). Compared with cells incubated without FA, the number of cancer cells was reduced from 25 to 67 % (P<0.0001) following FA treatment. Antiproliferative effects of CLA mixtures varied in magnitude according to the source of FA, the CLA composition and the cell lines. CLA mixtures naturally present in beef inhibited the proliferation of human cancer cell lines, a high content in cis-trans isomers allowing the most important antiproliferative effect. Beef total FA exhibited a greater growth-inhibitory activity than their corresponding CLA-enriched fractions. These results suggested that either beef FA other than beef CLA could possess antiproliferative properties and/or the existence of complementary effects of non-conjugated FA and CLA, which could favour the antiproliferative properties of beef total FA. PMID:16469152

  19. Multispectroscopic and docking studies on the binding of chlorogenic acid isomers to human serum albumin: Effects of esteryl position on affinity.

    PubMed

    Tang, Bin; Huang, Yanmei; Ma, Xiangling; Liao, Xiaoxiang; Wang, Qing; Xiong, Xinnuo; Li, Hui

    2016-12-01

    Structural differences among various dietary polyphenols affect their absorption, metabolism, and bioactivities. In this work, chlorogenic acid (CA) and its two positional isomers, neochlorogenic acid (NCA) and cryptochlorogenic acid (CCA), were investigated for their binding reactions with human serum albumin (HSA) using fluorescence, ultraviolet-visible, Fourier transform infrared and circular dichroism spectroscopies, as well as molecular docking. All three isomers were bound to HSA at Sudlow's site I and affected the protein secondary structure. CCA presented the strongest ability of hydrogen-bond formation, and both CA and NCA generated more electrostatic interactions with HSA. The albumin-binding capacity of these compounds decreased in the order CCA>NCA>CA. The compound with 4-esteryl structure showed higher binding affinity and larger conformational changes to HSA than that with 3- or 5-esteryl structures. These comparative studies on structure-affinity relationship contributed to the structural modification and design of phenolic food additives or new polyphenol-like drugs. PMID:27374553

  20. Analysis of a series of chlorogenic acid isomers using differential ion mobility and tandem mass spectrometry.

    PubMed

    Willems, Jamie L; Khamis, Mona M; Mohammed Saeid, Waleed; Purves, Randy W; Katselis, George; Low, Nicholas H; El-Aneed, Anas

    2016-08-24

    Chlorogenic acids are among the most abundant phenolics found in the human diet. Of these, the mono-caffeoylquinic acids are the predominant phenolics found in fruits, such as apples and pears, and products derived from them. In this research, a comprehensive study of the electrospray ionization (ESI) tandem mass spectrometric (MS/MS) dissociation behavior of the three most common mono-caffeoylquinic acids, namely 5-O-caffeoylquinic acid (5-CQA), 3-O-caffeoylquinic acid (3-CQA) and 4-O-caffeoylquinic acid (4-CQA), were determined using both positive and negative ionization. All proposed structures of the observed product ions were confirmed with second-generation MS(3) experiments. Similarities and differences between the dissociation pathways in the positive and negative ion modes are discussed, confirming the proposed structures and the established MS/MS fingerprints. MS/MS dissociation was primarily driven via the cleavage of the ester bond linking the quinic acid moiety to the caffeic acid moiety within tested molecules. Despite being structural isomers with the same m/z values and dissociation behaviors, the MS/MS data in the negative ion mode was able to differentiate the three isomers based on ion intensity for the major product ions, observed at m/z 191, 179 and 173. This differentiation was consistent among various MS instruments. In addition, ESI coupled with high-field asymmetric waveform ion mobility spectrometry-mass spectrometry (ESI-FAIMS-MS) was employed for the separation of these compounds for the first time. By combining MS/MS data and differential ion mobility, a method for the separation and identification of mono-caffeoylquinic in apple/pear juice samples was developed with a run time of less than 1 min. It is envisaged that this methodology could be used to identify pure juices based on their chlorogenic acid profile (i.e., metabolomics), and could also be used to detect juice-to-juice adulteration (e.g., apple juice addition to pear juice

  1. Biological and Chemical Properties of the Epidioxide Isomer of Abscisic Acid and its Rearrangement Products

    PubMed Central

    Sondheimer, Ernest; Michniewicz, Barbara M.; Powell, Loyd E.

    1969-01-01

    The growth inhibitory activity of the epidioxide (II), a precursor in the synthesis of abscisic acid (ABA), has been confirmed with additional assay systems. Under physiological conditions the epidioxide is rearranged to give ABA and an isomer of ABA which has probably the structure V. This major product has very low, if any, biological activity. The biological activity of the epidioxide is explained by its partial conversion (about 20%) to ABA. The reaction rate was enhanced by heavy metal ions and decreased by EDTA. At pH 12.5, the decomposition of the epidioxide is slower than it is near neutrality and ABA is the predominant product. In the biological systems studied the activity of the epidioxide can be accounted for by nonenzymatic conversion to ABA. PMID:16657047

  2. Comment on: MALDI ionization mechanisms investigated by comparison of isomers of dihydroxybenzoic acid.

    PubMed

    Chen, Jien-Lian; Ni, Chi-Kung

    2016-06-01

    Ionization mechanism of matrix-assisted laser desorption/ionization was recently investigated by Kirmess et al. (J. Mass Spectrom. 2016, 51, 79). The authors compared the ion yields of dihydroxybenzoic acid isomers between experimental measurements and theoretical models and claimed that the predictions of chemical and physical dynamics model are in good agreement with experimental data, but the predictions of thermal model are not. Here, we show that wrong S1-S1 energy pooling rate constants and absorption cross sections were used in the aforementioned article. In addition, we suggest the authors to list the values of many parameters used in their calculations and describe how they obtained these values because these values are completely unknown. PMID:27270870

  3. Radiochemically pure (1-/sup 14/C)valproic acid--a mixture of labeled structural isomers

    SciTech Connect

    Dickinson, R.G.; Wood, B.T.; Kluck, R.M.; Hooper, W.D.

    1986-01-01

    Ongoing studies of the disposition of valproic acid (VPA) and its glucuronide conjugate required the radiolabeled drug for greater sensitivity and tracing of oxidation metabolites. (1-/sup 14/C)VPA hereinafter called LABEL (radiochemical purity greater than 98% as determined by paper and thin layer chromatography) was purchased from Amersham International, U.K. Quantitative analysis of VPA and VPA-glucuronide in bile and urine samples from rats given VPA and tracer LABEL by our standard gas chromatographic assay showed gross discrepancies with the results obtained by liquid scintillation counting of the same extracts. Examination of the purity of LABEL was therefore undertaken. Equilibration of LABEL between various organic-aqueous solvent pairs was identical to that of authentic VPA. However, gas chromatographic-mass spectrometric analysis of the trimethylsilyl derivative of LABEL revealed it to be a mixture of labeled 2-methylheptanoic acid (approximately 60%), 2-ethylhexanoic acid (approximately 30%), and 2-propylpentanoic acid (i.e., VPA, 5-10%). The origin of the isomers of VPA in LABEL was logically traced to the synthetic procedure--coupling of the Grignard reagent of (an isomeric mixture of 2-, 3-, and 4-) chloroheptane(s) with (/sup 14/C)carbon dioxide. This result highlights the inadequacy of the quality control procedures used and reinforces the necessity for caution in accepting the quoted purity of radiolabeled drugs.

  4. Interstellar isomers

    NASA Technical Reports Server (NTRS)

    Defrees, D.; Mclean, D.; Herbst, E.

    1986-01-01

    Both observational and theoretical studies of molecular clouds are hindered by many difficulties. One way to partially circumvent the difficulties of characterizing the chemistry within these objects is to study the relative abundances of isomers which are synthesized from a common set of precursors. Unfortunately, only one such system has been confirmed, the HCN/HNC pair of isomers. While the basic outlines of its chemistry have been known for some years, there are still many aspects of the chemistry which are unclear. Another potential pair of isomers is HCO+/HOC+; HCO+ is an abundant instellar molecule and a tentative identification of HOC+ has been made in Sgr B2. This identification is being challenged, however, based on theoretical and laboratory evidence that HOC+ reacts with H2. Another potential pair of interstellar isomers is methyl cyanide (CH3CN, acetonitrile) and methyl isocyanide (CH3NC). The cyanide is well known, however the isocyanide has yet to be observed despite theoretical predictions that appreciable quantities should be present.

  5. Regiospecific Distribution of trans-Octadecenoic Acid Positional Isomers in Triacylglycerols of Partially Hydrogenated Vegetable Oil and Ruminant Fat.

    PubMed

    Yoshinaga, Kazuaki; Kawamura, Yoshinori; Kitayama, Takashi; Nagai, Toshiharu; Mizobe, Hoyo; Kojima, Koichi; Watanabe, Yomi; Sato, Shinichi; Beppu, Fumiaki; Gotoh, Naohiro

    2015-01-01

    It is revealed that binding position of fatty acid in triacylglycerol (TAG) deeply relates to the expression of its function. Therefore, we investigated the binding positions of individual trans-octadecenoic acid (trans-C18:1) positional isomers, known as unhealthy fatty acids, on TAG in partially hydrogenated canola oil (PHCO), milk fat (MF), and beef tallow (BT). The analysis was carried out by the sn-1(3)-selective transesterification of Candida antarctica Lipase B and by using a highly polar ionic liquid capillary column for gas chromatography-flame ionization detection. Trans-9-C18:1, the major trans-C18:1 positional isomer, was selectively located at the sn-2 position of TAG in PHCO, although considerable amounts of trans-9-C18:1 were also esterified at the sn-1(3) position. Meanwhile, trans-11-C18:1, the major isomer in MF and BT, was preferentially located at the sn-1(3) position. These results revealed that the binding position of trans-C18:1 positional isomer varies between various fats and oils. PMID:26028327

  6. Effect of dietary conjugated linoleic acid isomers on lipid metabolism in hamsters fed high-carbohydrate and high- fat diets

    PubMed Central

    Tarling, Elizabeth J.; Ryan, Kevin J.P.; Bennett, Andrew J.; Salter, Andrew M.

    2008-01-01

    Dietary conjugated linoleic acids (CLA), have been reported to have a number of isomer-dependent effects on lipid metabolism including reduction in adipose tissue deposition, changes in plasma lipoprotein concentrations and hepatic lipid accumulation. The aim of this study was to compare the effect of individual CLA isomers against lipogenic and high “Western” fat background diets. Golden Syrian hamsters were fed a high-carbohydrate rodent chow or chow supplemented with 17.25% fat formulated to represent the type and amount of fatty acids found in a typical “Western” diet (including 0.2% cholesterol). Diets were further supplemented with 0.25% (w/w) rapeseed oil, cis9, trans11 (c9,t11)-CLA or trans10, cis12 (t10,c12)-CLA. Neither isomer had a significant impact on plasma lipid or lipoprotein concentrations. The t10,c12-CLA isomer significantly reduced perirenal adipose tissue depot mass. While adipose tissue acetyl coenzyme A carboxylase and fatty acid synthase mRNA concentrations (as measured by quantitative PCR) were unaffected by CLA, lipoprotein lipase mRNA was specifically reduced by t10,c12-CLA, on both background diets (p<0.001). This was associated with a specific reduction of SREBP1c expression in perirenal adipose tissue (p=0.018). The isomers appear to have divergent effects on liver triacylglycerol content with c9,t11-CLA producing lower concentrations than t10,c12-CLA. We conclude that t10,c12-CLA modestly reduces adipose tissue deposition in the Golden Syrian hamster independently of background diet and this may possibly result from reduced uptake of lipoprotein fatty acids, as a consequence of reduced LPL gene expression. PMID:18983716

  7. Hydroxyalkylation of phenol to bisphenol F over heteropolyacid catalysts: The effect of catalyst acid strength on isomer distribution and kinetics.

    PubMed

    Wu, Xianzhang; Liu, Yutang; Liu, Ran; Wang, Longlu; Lu, Yanbing; Xia, Xinnian

    2016-11-01

    Hydroxyalkylation of phenol with formaldehyde to bisphenol F over heteropolyacid impregnated on clay was investigated. These catalysts displayed excellent catalytic performance for this reaction, especially that the effects of acid sites on the isomer distribution are obvious. Various solid catalysts were prepared by impregnating heteropolyacid on different kind of clay matrices, and their chemical compositions, textural properties, and acid strength of the heteropolyacid catalysts were characterized by EDX, BET, NH3-TPD, XRD, and FT-IR. Moreover, the effects of acid sites and reaction temperature on the yield and 4,4'-isomer distribution were launched by comparing the data obtained from the two kinds of catalysts. Furthermore, the kinetics of the hydroxyalkylation of phenol to BPF was established. PMID:27451037

  8. Analysis of histidine and urocanic acid isomers by reversed-phase high-performance liquid chromatography.

    PubMed

    Hermann, K; Abeck, D

    2001-01-01

    The qualitative separation performance of a C18, C8 and C4 reversed-phase column was investigated for the separation of histidine and its metabolites histamine, 1-methyihistamine and trans- and cis-urocanic acid. Trans- and cis-urocanic acid were baseline separated from their precursor histidine on all three columns using isocratic elution with a mobile phase composed of 0.01 M aqueous TEAP pH 3.0 and acetonitrile at a ratio of 98:2 (v/v). However, histidine was not separated from histamine and 1-methyihistamine. Selecting the C8 column and introducing 0.005 M of the ion pairing reagent 1-octanesulfonic acid sodium salt into the aqueous solution and acetonitrile at a ratio of 90:10 (v/v), significantly improved the separation. The separation was also followed by a change in the retention times and the order of elution. The sequence of elution was histidine, cis-urocanic acid, trans-urocanic acid, histamine and 1-methylhistamine with retention times of 5.58 +/- 0.07, 7.03 +/- 0.15, 7.92 +/- 0.18, 18.77 +/- 0.24 and 20.79 +/- 0.21 min (mean +/- SD; n=5). The separation on the C8 column in the presence of the ion-pairing reagent was further improved with gradient elution that resulted in a reduction in the retention times and elution volumes of histamine and 1-methylhistamine. The detection limits of histidine and trans-urocanic acid at a wavelength of 210 nm and an injection volume of 0.05 ml were 5 x 10(-8) mol l(-1) (n=3). The kinetic of the in-vitro conversion of trans- into the cis-isomer after UV irradiation was depending on the time of exposure and the energy of the light source. UVB light induced a significantly faster conversion than UVA light. TUCA and cUCA samples kept at -25 degrees C were stable for up to 50 weeks. Samples, eluted from human skin showed various concentrations of histidine and trans- and cis-urocanic acid with an average of 1.69 +/- 0.33 x 10(-5) mol l(-1), 1.17 +/- 0.43 x 10(-5) mol l(-1) and 1.67 +/- 0.33 x 10(-5) mol l(-1), respectively

  9. Estimated pKa values for the environmentally relevant C1 through C8 perfluorinated sulfonic acid isomers.

    PubMed

    Rayne, Sierra; Forest, Kaya

    2016-10-14

    In order to estimate isomer-specific acidity constants (pKa) for the perfluorinated sulfonic acid (PFSA) environmental contaminants, the parameterization method 6 (PM6) pKa prediction method was extensively validated against a wide range of carbon oxyacids and related sulfonic/sulfinic acids. Excellent pKa prediction performance was observed for the carbon oxyacids using the PM6 method, but this approach was found to have a severe positive bias for sulfonic/sulfinic acids. To overcome this obstacle, a correlation was developed between non-adjusted PM6 pKa values and the corresponding experimentally obtained/estimated acidity constants for a range of representative alkyl, aryl and halogen-substituted sulfonic acids. Application of this correction to the PM6 values allows for extension of this computational method to a new acid functional group. When used to estimate isomer-specific pKa values for the C1 through C8 PFSAs, the modified PM6 approach suggests an adjusted pKa range from -5.3 to -9.0, indicating that all members of this class of well-known environmental contaminants will be effectively completely dissociated in aquatic systems. PMID:27389973

  10. Isomers of various species of 1-hydroxy-2-pyridinone-6-carboxylic acid, their proton dissociation and complexes with Cr(III) and Zn(II)

    NASA Astrophysics Data System (ADS)

    Thipyapong, Khajadpai; Ruangpornvisuti, Vithaya

    2008-11-01

    Isomers of 1-hydroxy-2-pyridinone-6-carboxylic acid (6-carboxy-1,2-HOPO), their deprotonated species and complexes with chromium and zinc were theoretically investigated by density functional theory calculations. Free energy of activation, energetics, thermodynamic properties and equilibrium constants of interconversion reactions of their isomers were determined. Measured acid-dissociation constants of the 6-carboxy-1,2-HOPO obtained from potentiometric titration method were compared with the computed constants which were derived from the density functional theory method. Two isomers of each 6-carboxy-1,2-HOPO complexes with chromium and with zinc were found.

  11. Power optimization in logic isomers

    NASA Technical Reports Server (NTRS)

    Panwar, Ramesh; Rennels, David; Alkalaj, Leon

    1993-01-01

    Logic isomers are labeled, 2-isomorphic graphs that implement the same logic function. Logic isomers may have significantly different power requirements even though they have the same number of transistors in the implementation. The power requirements of the isomers depend on the transition activity of the input signals. The power requirements of isomorphic graph isomers of n-input NAND and NOR gates are shown. Choosing the less power-consuming isomer instead of the others can yield significant power savings. Experimental results on a ripple-carry adder are presented to show that the implementation using the least power-consuming isomers requires approximately 10 percent less power than the implementation using the most power-consuming isomers. Simulations of other random logic designs also confirm that designs using less power-consuming isomers can reduce the logic power demand by approximately 10 percent as compared to designs using more power-consuming isomers.

  12. Hexadecenoic Fatty Acid Isomers in Human Blood Lipids and Their Relevance for the Interpretation of Lipidomic Profiles

    PubMed Central

    Sansone, Anna; Tolika, Evanthia; Louka, Maria; Sunda, Valentina; Deplano, Simone; Melchiorre, Michele; Anagnostopoulos, Dimitrios; Chatgilialoglu, Chryssostomos; Formisano, Cesare; Di Micco, Rosa; Faraone Mennella, Maria Rosaria; Ferreri, Carla

    2016-01-01

    Monounsaturated fatty acids (MUFA) are emerging health biomarkers, and in particular the ratio between palmitoleic acid (9cis-16:1) and palmitic acid (16:0) affords the delta-9 desaturase index that is increased in obesity. Recently, other positional and geometrical MUFA isomers belonging to the hexadecenoic family (C16 MUFA) were found in circulating lipids, such as sapienic acid (6cis-16:1), palmitelaidic acid (9trans-16:1) and 6trans-16:1. In this work we report: i) the identification of sapienic acid as component of human erythrocyte membrane phospholipids with significant increase in morbidly obese patients (n = 50) compared with age-matched lean controls (n = 50); and ii) the first comparison of erythrocyte membrane phospholipids (PL) and plasma cholesteryl esters (CE) in morbidly obese patients highlighting that some of their fatty acid levels have opposite trends: increases of both palmitic and sapienic acids with the decrease of linoleic acid (9cis,12cis-18:2, omega-6) in red blood cell (RBC) membrane PL were reversed in plasma CE, whereas the increase of palmitoleic acid was similar in both lipid species. Consequentially, desaturase enzymatic indexes gave different results, depending on the lipid class used for the fatty acid content. The fatty acid profile of morbidly obese subjects also showed significant increases of stearic acid (C18:0) and C20 omega-6, as well as decreases of oleic acid (9cis-18:1) and docosahexaenoic acid (C22:6 omega-3) as compared with lean healthy controls. Trans monounsaturated and polyunsaturated fatty acids were also measured and found significantly increased in both lipid classes of morbidly obese subjects. These results highlight the C16 MUFA isomers as emerging metabolic marker provided that the assignment of the double bond position and geometry is correctly performed, thus identifying the corresponding lipidomic pathway. Since RBC membrane PL and plasma CE have different fatty acid trends, caution must also be used in the

  13. Hexadecenoic Fatty Acid Isomers in Human Blood Lipids and Their Relevance for the Interpretation of Lipidomic Profiles.

    PubMed

    Sansone, Anna; Tolika, Evanthia; Louka, Maria; Sunda, Valentina; Deplano, Simone; Melchiorre, Michele; Anagnostopoulos, Dimitrios; Chatgilialoglu, Chryssostomos; Formisano, Cesare; Di Micco, Rosa; Faraone Mennella, Maria Rosaria; Ferreri, Carla

    2016-01-01

    Monounsaturated fatty acids (MUFA) are emerging health biomarkers, and in particular the ratio between palmitoleic acid (9cis-16:1) and palmitic acid (16:0) affords the delta-9 desaturase index that is increased in obesity. Recently, other positional and geometrical MUFA isomers belonging to the hexadecenoic family (C16 MUFA) were found in circulating lipids, such as sapienic acid (6cis-16:1), palmitelaidic acid (9trans-16:1) and 6trans-16:1. In this work we report: i) the identification of sapienic acid as component of human erythrocyte membrane phospholipids with significant increase in morbidly obese patients (n = 50) compared with age-matched lean controls (n = 50); and ii) the first comparison of erythrocyte membrane phospholipids (PL) and plasma cholesteryl esters (CE) in morbidly obese patients highlighting that some of their fatty acid levels have opposite trends: increases of both palmitic and sapienic acids with the decrease of linoleic acid (9cis,12cis-18:2, omega-6) in red blood cell (RBC) membrane PL were reversed in plasma CE, whereas the increase of palmitoleic acid was similar in both lipid species. Consequentially, desaturase enzymatic indexes gave different results, depending on the lipid class used for the fatty acid content. The fatty acid profile of morbidly obese subjects also showed significant increases of stearic acid (C18:0) and C20 omega-6, as well as decreases of oleic acid (9cis-18:1) and docosahexaenoic acid (C22:6 omega-3) as compared with lean healthy controls. Trans monounsaturated and polyunsaturated fatty acids were also measured and found significantly increased in both lipid classes of morbidly obese subjects. These results highlight the C16 MUFA isomers as emerging metabolic marker provided that the assignment of the double bond position and geometry is correctly performed, thus identifying the corresponding lipidomic pathway. Since RBC membrane PL and plasma CE have different fatty acid trends, caution must also be used in the

  14. Screening of urocanic acid isomers in human basal and squamous cell carcinoma tumors compared with tumor periphery and healthy skin.

    PubMed

    Decara, Juan Manuel; Aguilera, José; Abdala, Roberto; Sánchez, Purificación; Figueroa, Félix L; Herrera, Enrique

    2008-10-01

    Trans-urocanic acid is a major chromophore for ultraviolet (UV) radiation in human epidermis. The UV induces photoisomerization of trans-urocanic acid (tUCA) form to cis-urocanic acid (cUCA) and has been reported as an important mediator in the immunosuppression induced by UV. This immunomodulation has been recognized as an important factor related to skin cancer development. This is the first time that UCA isomers have been measured in epidermis of skin biopsies from patients with squamous cell carcinoma (SCC) and with basal cell carcinoma (BCC) and compared with the tumor periphery and biopsies of healthy photoexposed and non-photoexposed skin as controls. The UCA isomers were separated and quantified by high performance liquid chromatography. Analysis of UCA in healthy skin showed significant increase in total UCA content in non-photoexposed body sites compared with highly exposed skins. In contrast, the percentage of cUCA was higher in photoexposed body sites. Maximal levels of cUCA were found in cheek, forehead and forearm and lower levels in abdomen and thigh. No differences were found in total UCA concentration between the tumor samples and healthy photoexposed skin. However, differences were found in relation between isomers. Higher levels of cUCA were detected in SCC biopsies (44% of total UCA) compared with samples of BCC and that of healthy photoexposed skin (30%). These results suggest that the UV radiation exposure, a main factor in development of SCC can be mediated, apart from direct effect to cells (DNA damage), by immunosuppression pathways mediated by high production of cUCA. PMID:18312386

  15. Isolation of isochlorogenic acid isomers in flower buds of Lonicera japonica by high-speed counter-current chromatography and preparative high performance liquid chromatography.

    PubMed

    Guo, Wei; Wang, Liang; Gao, Yan; Zhao, Bonian; Wang, Daijie; Duan, Wenjuan; Yu, Zongyuan

    2015-02-15

    An efficient method was established by HSCCC combined with prep-HPLC for separating isochlorogenic acid isomers from flower buds of Lonicera japonica. The partially purified sample from the methanol extract of flower buds of L. japonica by silica gel column was separated by HSCCC to result in a fraction containing two isochlorogenic acid isomers. The fraction was further isolated by prep-HPLC to yield isochlorogenic acid A and isochlorogenic acid C with purities of 98% and 96%, and the total recoveries at 80.1% and 79.8%, respectively. The chemical structures of isochlorogenic acid isomers were confirmed by electrospray ionization mass spectrometry (ESI-MS) and (1)H nuclear magnetic resonance (NMR). PMID:25596381

  16. Application of Attenuated Total Reflectance-Fourier Transformed Infrared (ATR-FTIR) Spectroscopy To Determine the Chlorogenic Acid Isomer Profile and Antioxidant Capacity of Coffee Beans.

    PubMed

    Liang, Ningjian; Lu, Xiaonan; Hu, Yaxi; Kitts, David D

    2016-01-27

    The chlorogenic acid isomer profile and antioxidant activity of both green and roasted coffee beans are reported herein using ATR-FTIR spectroscopy combined with chemometric analyses. High-performance liquid chromatography (HPLC) quantified different chlorogenic acid isomer contents for reference, whereas ORAC, ABTS, and DPPH were used to determine the antioxidant activity of the same coffee bean extracts. FTIR spectral data and reference data of 42 coffee bean samples were processed to build optimized PLSR models, and 18 samples were used for external validation of constructed PLSR models. In total, six PLSR models were constructed for six chlorogenic acid isomers to predict content, with three PLSR models constructed to forecast the free radical scavenging activities, obtained using different chemical assays. In conclusion, FTIR spectroscopy, coupled with PLSR, serves as a reliable, nondestructive, and rapid analytical method to quantify chlorogenic acids and to assess different free radical-scavenging capacities in coffee beans. PMID:26725502

  17. Reaction between peroxynitrite and triphenylphosphonium-substituted arylboronic acid isomers: identification of diagnostic marker products and biological implications.

    PubMed

    Sikora, Adam; Zielonka, Jacek; Adamus, Jan; Debski, Dawid; Dybala-Defratyka, Agnieszka; Michalowski, Bartosz; Joseph, Joy; Hartley, Richard C; Murphy, Michael P; Kalyanaraman, Balaraman

    2013-06-17

    Aromatic boronic acids react rapidly with peroxynitrite (ONOO(-)) to yield phenols as major products. This reaction was used to monitor ONOO(-) formation in cellular systems. Previously, we proposed that the reaction between ONOO(-) and arylboronates (PhB(OH)2) yields a phenolic product (major pathway) and a radical pair PhB(OH)2O(•-)···(•)NO2 (minor pathway). [Sikora, A. et al. (2011) Chem. Res. Toxicol. 24, 687-697]. In this study, we investigated the influence of a bulky triphenylphosphonium (TPP) group on the reaction between ONOO(-) and mitochondria-targeted arylboronate isomers (o-, m-, and p-MitoPhB(OH)2). Results from the electron paramagnetic resonance (EPR) spin-trapping experiments unequivocally showed the presence of a phenyl radical intermediate from meta and para isomers, and not from the ortho isomer. The yield of o-MitoPhNO2 formed from the reaction between o-MitoPhB(OH)2 and ONOO(-) was not diminished by phenyl radical scavengers, suggesting a rapid fragmentation of the o-MitoPhB(OH)2O(•-) radical anion with subsequent reaction of the resulting phenyl radical with (•)NO2 in the solvent cage. The DFT quantum mechanical calculations showed that the energy barrier for the dissociation of the o-MitoPhB(OH)2O(•-) radical anion is significantly lower than that of m-MitoPhB(OH)2O(•-) and p-MitoPhB(OH)2O(•-) radical anions. The nitrated product, o-MitoPhNO2, is not formed by the nitrogen dioxide radical generated by myeloperoxidase in the presence of the nitrite anion and hydrogen peroxide, indicating that this specific nitrated product may be used as a diagnostic marker product for ONOO(-). Incubation of o-MitoPhB(OH)2 with RAW 264.7 macrophages activated to produce ONOO(-) yielded the corresponding phenol o-MitoPhOH as well as the diagnostic nitrated product, o-MitoPhNO2. We conclude that the ortho isomer probe reported here is most suitable for specific detection of ONOO(-) in biological systems. PMID:23611338

  18. Determination of Exposure to the Alternaria Mycotoxin Tenuazonic Acid and Its Isomer allo-Tenuazonic Acid in a German Population by Stable Isotope Dilution HPLC-MS(3).

    PubMed

    Hövelmann, Yannick; Hickert, Sebastian; Cramer, Benedikt; Humpf, Hans-Ulrich

    2016-08-31

    The content of the Alternaria toxin tenuazonic acid and its isomer allo-tenuazonic acid was quantitated in urine of a German cohort (n = 48) using a newly developed and successfully validated solid phase extraction based stable isotope dilution HPLC-MS(3) method. Tenuazonic acid was detected in all of the samples and quantifiable in 97.9% of these samples in a range of 0.16-44.4 ng/mL (average = 6.58 ng/mL) or 0.07-63.8 ng/mg creatinine (average = 8.13 ng/mg creatinine). allo-Tenuazonic acid was for the first time detected in human urine (95.8% of the samples positive) and quantitated in 68.8% of the samples in a range of 0.11-5.72 ng/mL (average = 1.25 ng/mL) or 0.08-10.1 ng/mg creatinine (average = 1.52 ng/mg creatinine), representing 3.40-25.0% of the sum of both isomers (average = 12.4%). Food-frequency questionnaires were used to document food consumption of study participants to correlate mycotoxin exposure to nutritional habits. Although no statistically significant correlation between consumption of a specific food and urinary excretion of tenuazonic acid could be determined, a trend regarding elevated intake of cereal products and higher excretion of tenuazonic acid was evident. On the basis of these results, a provisional mean daily intake (PDI) for both tenuazonic acid and allo-tenuazonic acid was calculated, being 0.183 and 0.025 μg/kg body weight, respectively. A combined mean PDI for both isomers amounts to 0.208 μg/kg body weight with the highest individual PDI for one of the participants (1.582 μg/kg body weight) slightly exceeding the threshold of toxicological concern assumed for tenuazonic acid by the European Food Safety Authority of 1.500 μg/kg body weight. This is the first study to investigate the tenuazonic acid content in human urine of a larger sample cohort enabling the calculation of PDIs for tenuazonic acid and allo-tenuazonic acid. PMID:27452834

  19. Zeolite-Catalyzed Isomerization of Oleic Acid to Branched-Chain Isomers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Branched-chain saturated fatty acids have potential as oleochemical intermediates since they have better oxidative stability than linear unsaturated fatty acids and have better low-temperature properties than linear saturated fatty acids. Previous studies in converting unsaturated fatty acids to br...

  20. Synthesis of framework isomer MOFs containing zinc and 4-tetrazolyl benzenecarboxylic acid via a structure directing solvothermal approach

    SciTech Connect

    Ordonez, Carlos; Kinnibrugh, Tiffany L.; Xu, Hongwu; Lindline, Jennifer; Timofeeva, Tatiana; Wei, Qiang

    2015-04-02

    The solvothermal synthesis of framework isomers was carried out using the hybrid carboxylate and tetrazolate functional ligand, 4-tetrazolyl benzenecarboxylic acid (H₂TBC, TBC = 4-tetrazolyl benzenecarboxylate) and zinc. H₂TBC was also synthesized with the solvothermal approach, and is referred herein as structure 1. Using single-crystal X-ray diffraction, we found that the tetrazolate groups of TBC show an unusual “opposite-on” coordination mode with zinc. Three previously characterized metal-organic frameworks (MOFs) were obtained by systematically changing the solvents of the H₂TBC-Zn reaction, (1) ZnTBC, 2, which has a non-porous structure; (2) Zn₂(TBC)₂(H2O), 3, which has an amphiphilic pore structure and (3) Zn₂(TBC)₂{guest}, 4, which is porous and has channels containing uncoordinated N heteroatoms. Fluorescence spectra of 4 reveal a strong blue emission mainly from the TBC ligands.

  1. Synthesis of framework isomer MOFs containing zinc and 4-tetrazolyl benzenecarboxylic acid via a structure directing solvothermal approach

    DOE PAGESBeta

    Ordonez, Carlos; Kinnibrugh, Tiffany L.; Xu, Hongwu; Lindline, Jennifer; Timofeeva, Tatiana; Wei, Qiang

    2015-04-02

    The solvothermal synthesis of framework isomers was carried out using the hybrid carboxylate and tetrazolate functional ligand, 4-tetrazolyl benzenecarboxylic acid (H₂TBC, TBC = 4-tetrazolyl benzenecarboxylate) and zinc. H₂TBC was also synthesized with the solvothermal approach, and is referred herein as structure 1. Using single-crystal X-ray diffraction, we found that the tetrazolate groups of TBC show an unusual “opposite-on” coordination mode with zinc. Three previously characterized metal-organic frameworks (MOFs) were obtained by systematically changing the solvents of the H₂TBC-Zn reaction, (1) ZnTBC, 2, which has a non-porous structure; (2) Zn₂(TBC)₂(H2O), 3, which has an amphiphilic pore structure and (3) Zn₂(TBC)₂{guest}, 4,more » which is porous and has channels containing uncoordinated N heteroatoms. Fluorescence spectra of 4 reveal a strong blue emission mainly from the TBC ligands.« less

  2. Conjugated linoleic acid isomers, t10c12 and c9t11, are differentially incorporated into adipose tissue and skeletal muscle in humans.

    PubMed

    Goedecke, Julia H; Rae, Dale E; Smuts, Cornelius M; Lambert, Estelle V; O'Shea, Marianne

    2009-11-01

    Conjugated linoleic acid (CLA) is a popular supplement believed to enhance immune function, body composition and insulin sensitivity, but results of scientific studies investigating its effects are conflicting. The isomer- and tissue-specific effects of CLA may explain these conflicting results. Therefore, this study quantified the incorporation of the c9t11 and t10c12 CLA isomers into adipose tissue and skeletal muscle in response to supplementation in healthy, regularly-exercising, non-obese persons. The CLA group (n = 14) ingested 3.9 g per day CLA (50:50 t9c11:c10t12) and the placebo group (n = 11) 3.9 g per day high-oleic-acid sunflower oil for 12 weeks. Following supplementation, the t10c12 isomer was incorporated into adipose tissue triacylglycerol (P < 0.001), and the c9t11 isomer tended to increase in skeletal muscle phospholipids (P = 0.056). Therefore, human adipose tissue and skeletal muscle are enriched with CLA in an isomer-specific manner. PMID:19851798

  3. The conjugated linoleic acid isomer trans-9,trans-11 is a dietary occurring agonist of liver X receptor {alpha}

    SciTech Connect

    Ecker, Josef; Liebisch, Gerhard; Patsch, Wolfgang; Schmitz, Gerd

    2009-10-30

    Conjugated linoleic acid (CLA) isomers are dietary fatty acids that modulate gene expression in many cell types. We have previously reported that specifically trans-9,trans-11 (t9,t11)-CLA induces expression of genes involved in lipid metabolism of human macrophages. To elucidate the molecular mechanism underlying this transcriptional activation, we asked whether t9,t11-CLA affects activity of liver X receptor (LXR) {alpha}, a major regulator of macrophage lipid metabolism. Here we show that t9,t11-CLA is a regulator of LXR{alpha}. We further demonstrate that the CLA isomer induces expression of direct LXR{alpha} target genes in human primary macrophages. Knockdown of LXR{alpha} with RNA interference in THP-1 cells inhibited t9,t11-CLA mediated activation of LXR{alpha} including its target genes. To evaluate the effective concentration range of t9,t11-CLA, human primary macrophages were treated with various doses of CLA and well known natural and synthetic LXR agonists and mRNA expression of ABCA1 and ABCG1 was analyzed. Incubation of human macrophages with 10 {mu}M t9,t11-CLA led to a significant modulation of ABCA1 and ABCG1 transcription and caused enhanced cholesterol efflux to high density lipoproteins and apolipoprotein AI. In summary, these data show that t9,t11-CLA is an agonist of LXR{alpha} in human macrophages and that its effects on macrophage lipid metabolism can be attributed to transcriptional regulations associated with this nuclear receptor.

  4. Identification of a dicaffeoylquinic acid isomer from Arctium lappa with a potent anti-ulcer activity.

    PubMed

    Carlotto, Juliane; da Silva, Luisa M; Dartora, Nessana; Maria-Ferreira, Daniele; Sabry, Diego de A; Filho, Arquimedes P S; de Paula Werner, Maria F; Sassaki, Guilherme L; Gorin, Philip A J; Iacomini, Marcello; Cipriani, Thales R; de Souza, Lauro M

    2015-04-01

    Leaves of Arctium lappa contain several mono- and dicaffeoylquinic acids, as evaluated by liquid chromatography-mass spectrometry. In order to investigate the protection on gastric mucosa against ulcers, rats were treated with fractions from leaf extract prior to ethanol-induced ulcers. The original fraction obtained as ethanol soluble fraction from hot aqueous extract was able to protect de gastric mucosa, and this effect was retained in the ethyl acetate fraction, obtained from liquid/liquid fractionation. The main compound in this fraction was isolated and chemically characterized by nuclear magnetic resonance and mass spectrometry, assisted by isopropylidene derivatization which gave rise a mass increment of 40 units. Therefore, the underivatized compound that had m/z 515.119 [M-H](-) was shifted to m/z 555.151, being confirmed as 1,3-O-dicaffeoylquinic acid, which presented an ED50 of 57 µg kg(-1) on gastric protection, lesser than the therapeutic concentration of omeprazole (40 mg kg(-1)). PMID:25640125

  5. Selective microbial degradation of saturated methyl branched chain fatty acid isomers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Three strains of Pseudomonas bacteria were screened for their capabilities of degrading chemically synthesized saturated branched-chain fatty acids (sbc-FAs). Mixtures of sbc-FAs with the methyl-branch located at various locales along the fatty acid were used as a carbon feedstock in shake-flask cu...

  6. Two new antioxidant malonated caffeoylquinic acid isomers in fruits of wild eggplant relatives

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fruits of both the cultivated eggplant species Solanum melongena and its wild relative Solanum incanum have a high content of hydroxycinnamic acid conjugates, which along with other phenylpropanoids are implicated in the human health benefits of various fruits and vegetables. Monocaffeoylquinic acid...

  7. Characterization of polyesters prepared from three different phthalic acid isomers by CID-ESI-FT-ICR and PSD-MALDI-TOF mass spectrometry.

    PubMed

    Laine, Olli; Laitinen, Tuomo; Vainiotalo, Pirjo

    2002-08-15

    Polyesters prepared from the same diol, 2-butyl-2-ethyl-1,3-propanediol, but different phthalic acid isomers, phthalic, isophthalic, and terephthalic acid, were characterized by collision-induced dissociation electrospray ionization Fourier transform ion cyclotron resonance (CID-ESI-FT-ICR) and postsource-decay matrix-assisted laser desorption/ionization time-of-flight (PSD-MALDI-TOF) mass spectrometry. Sodiated dihydroxyl-terminated polyester oligomers containing five repeating units at m/z 1634 were selected as precursor ions for dissociation studies. Two main mechanisms occurred in the fragmentation of all of the polyesters, since dissociation of the oligomers was initiated by hydrogen rearrangement or transesterification reactions. Polyesters prepared from different phthalic acid isomers could be distinguished by their fragmentation behavior. Polyester prepared from phthalic acid was easily identified by using both CID-ESI-FT-ICR and PSD-MALDI-TOF mass spectrometry. However, distinguishing between the polyesters prepared from isophthalic and terephthalic acid succeeded marginally only with CID-ESI-FT-ICR mass spectrometry. Molecular dynamics calculations were used to obtain an idea of the fragmentation behavior of the polyesters. The low-energy structures of the precursor ions were determined, and the coordination of the oxygen atoms of the polyester oligomers to the sodium cation was examined more closely. Both the experimental and the theoretical studies showed that the sodium ion affinity of polyester changed with the phthalic acid isomer. PMID:12199599

  8. Isomers/enantiomers of perfluorocarboxylic acids: Method development and detection in environmental samples

    EPA Science Inventory

    Perfluoroalkyl substances are globally distributed in both urban and remote settings, and routinely are detected in wildlife, humans, and the environment. One of the most prominent and routinely detected perfluoroalkyl substances is perfluorooctanoic acid (PFOA), which has been s...

  9. Isomer-sensitive deboronation in reductive aminations of aryl boronic acids

    SciTech Connect

    Jones, Brad Howard; Wheeler, David R.; Wheeler, Jill S.; Miller, Lance Lee; Alam, Todd M.; Spoerke, Erik David

    2015-09-05

    Deboronation is observed during the reductive amination of formylphenylboronic acid (FPBA) to the amine termini and side chains of peptides. This deboronation is sensitive to the isomerism of the boronic acid (BA), with ortho-FPBA yielding complete deboronation in the preparation of an N-terminally-modified dipeptide. The observed behavior is also clearly mediated by the chemical identity of the amine substrate. These results reveal a previously undocumented subtlety of BA functionalization and highlight the importance of thorough spectroscopic characterization in the preparation of peptide and small molecule BAs.

  10. Isomer-sensitive deboronation in reductive aminations of aryl boronic acids

    DOE PAGESBeta

    Jones, Brad Howard; Wheeler, David R.; Wheeler, Jill S.; Miller, Lance Lee; Alam, Todd M.; Spoerke, Erik David

    2015-09-05

    Deboronation is observed during the reductive amination of formylphenylboronic acid (FPBA) to the amine termini and side chains of peptides. This deboronation is sensitive to the isomerism of the boronic acid (BA), with ortho-FPBA yielding complete deboronation in the preparation of an N-terminally-modified dipeptide. The observed behavior is also clearly mediated by the chemical identity of the amine substrate. These results reveal a previously undocumented subtlety of BA functionalization and highlight the importance of thorough spectroscopic characterization in the preparation of peptide and small molecule BAs.

  11. Determination of 15 isomers of chlorobenzoic acid in soil samples using accelerated sample extraction followed by liquid chromatography.

    PubMed

    Křesinová, Zdena; Muzikář, Milan; Olšovská, Jana; Cajthaml, Tomáš

    2011-05-30

    A study was conducted to elaborate a fast, simple and efficient method for determination of 15 isomers chlorobenzoic acids (CBAs) in soil using HPLC-UV. Artificially contaminated soil samples were extracted using accelerated solvent extraction (ASE) with 1% acetic acid in a mixture of hexane and acetone (1:1, V/V) under a pressure of 10.34 MPa and temperature of 150°C. The recovery of the ASE method was above 82%. The extracts were concentrated; dimethyl sulfoxide was used to prevent CBA volatilization and the final analysis was performed with a C18 XBridge HPLC column employing a mobile phase consisting of acetonitrile and 0.1% trifluoracetic acid in water. A HPLC procedure with gradient elution and UV detection was developed and validated. The method exhibited a linear range for 2-CBA; 2,6-CBA; 3-CBA; 4-CBA; 2,3-CBA; 2,3,6-CBA; 2,5-CBA; and 2,4-CBA from 5 to 120 μg/mL with a limit of quantification (LOQ) of 5 μg/mL, RSD from 2.42 to 9.42% and accuracy from 82 ± 2 to 103 ± 3%. The linear range of determination of 2,4,6-CBA, 3,4-CBA, 2,3,5,6-CBA, 3,5-CBA, 2,3,5-CBA, 2,3,4,5,6-CBA and 2,3,4,5-CBA was 10-120 μg/mL with LOQ 10 μg/mL, RSD from 0.74 to 5.84% and accuracy from 94 ± 1 to 114 ± 1%. The optimized analytical procedure was finally applied on two historically PCB contaminated soils and 9 CBAs were quantified in the samples. PMID:21530790

  12. Effect of cis-9,trans-11 and trans-10,cis-12 isomers of conjugated linoleic acid on the integrity and functionality of cryopreserved bovine spermatozoa.

    PubMed

    Soares, Marcio Pereira; Brandelli, Adriano; Celeghini, Eneiva Carla Carvalho; de Arruda, Rubens Paes; Rodriguez, Shirley Andrea Florez

    2013-08-01

    Plasma membranes of sperm subjected to low temperatures undergo changes in their structure and permeability. The addition of fatty acids in semen cryopreservation media may influence the sperm motility after thawing, possibly by maintaining the membrane fluidity due to their incorporation in lipid bilayers. In this work, different concentrations of the isomers cis-9,trans-11 and trans-10,cis-12 of conjugated linoleic acid (CLA) were added in the cryopreservation medium of bovine sperm. Four Jersey bulls were used, and the ejaculates were processed as a pool. The Tris-based extender (Dilutris®) was supplemented with 20% egg yolk (MB). The treatments with CLA (Luta-CLA®), which had oily presentation, were prepared from MB with addition of 1% sodium lauryl sulfate, and denominated MBL. The concentrations of CLA tested were 50, 100, and 150 μM. The motility characteristics of the post-thaw semen were analyzed by computerized analysis system (CASA), and plasma membrane integrity and acrosomal and mitochondrial function assessed by the association of the fluorescent probes propidium iodide, fluorescein isothiocyanate-conjugated Pisum sativum agglutinin (FITC-PSA), JC-1 and Hoechst 33342. No significant differences were observed among treatments, excepting for a decreased mitochondrial potential of cells treated with 150 μM CLA. The addition of CLA, at the concentrations used, showed no advantages on the integrity and functionality of bovine sperm submitted to cryopreservation. PMID:23721967

  13. Atlas of Nuclear Isomers

    NASA Astrophysics Data System (ADS)

    Jain, Ashok Kumar; Maheshwari, Bhoomika; Garg, Swati; Patial, Monika; Singh, Balraj

    2015-09-01

    We present an atlas of nuclear isomers containing the experimental data for the isomers with a half-life ≥ 10 ns together with their various properties such as excitation-energy, half-life, decay mode(s), spin-parity, energies and multipolarities of emitted gamma transitions, etc. The ENSDF database complemented by the XUNDL database has been extensively used in extracting the relevant data. Recent literature from primary nuclear physics journals, and the NSR bibliographic database have been searched to ensure that the compiled data Table is as complete and current as possible. The data from NUBASE-12 have also been checked for completeness, but as far as possible original references have been cited. Many interesting systematic features of nuclear isomers emerge, some of them new; these are discussed and presented in various graphs and figures. The cutoff date for the extraction of data from the literature is August 15, 2015.

  14. Atlas of Nuclear Isomers

    SciTech Connect

    Jain, Ashok Kumar; Maheshwari, Bhoomika; Garg, Swati; Patial, Monika; Singh, Balraj

    2015-09-15

    We present an atlas of nuclear isomers containing the experimental data for the isomers with a half-life ≥ 10 ns together with their various properties such as excitation-energy, half-life, decay mode(s), spin-parity, energies and multipolarities of emitted gamma transitions, etc. The ENSDF database complemented by the XUNDL database has been extensively used in extracting the relevant data. Recent literature from primary nuclear physics journals, and the NSR bibliographic database have been searched to ensure that the compiled data Table is as complete and current as possible. The data from NUBASE-12 have also been checked for completeness, but as far as possible original references have been cited. Many interesting systematic features of nuclear isomers emerge, some of them new; these are discussed and presented in various graphs and figures. The cutoff date for the extraction of data from the literature is August 15, 2015.

  15. Synthesis of an Isomer of the Decalinoyltetramic Acid Methiosetin by a Stereocontrolled IMDA Reaction of a Metal-Chelated 3-Trienoyltetramate.

    PubMed

    Winterer, Markus; Kempf, Karl; Schobert, Rainer

    2016-09-01

    An isomer of the 3-decalinoyltetramic acid methiosetin was synthesized for the first time. The decalin moiety was established by a late-stage intramolecular Diels-Alder cyclization catalyzed by Me2AlCl or La(OTf)3. Its high diastereoselectivity arose from stereoinduction by a well-defined metal O,O-chelate complex of the 3-acyltetramic acid moiety. The nature of the metal and the bulkiness of the residues at the tetramic acid chelator are decisive for the stereochemical outcome. PMID:27551958

  16. Gas-Phase Formation Rates of Nitric Acid and Its Isomers Under Urban Conditions

    NASA Technical Reports Server (NTRS)

    Okumura, M.; Mollner, A. K.; Fry, J. L.; Feng, L.

    2005-01-01

    Ozone formation in urban smog is controlled by a complex set of reactions which includes radical production from photochemical processes, catalytic cycles which convert NO to NO2, and termination steps that tie up reactive intermediates in long-lived reservoirs. The reaction OH + NO2 + M -4 HONO2 + M (la) is a key termination step because it transforms two short-lived reactive intermediates, OH and NO2, into relatively long-lived nitric acid. Under certain conditions (low VOC/NOx), ozone production in polluted urban airsheds can be highly sensitive to this reaction, but the rate parameters are not well constrained. This report summarizes the results of new laboratory studies of the OH + NO2 + M reaction including direct determination of the overall rate constant and branching ratio for the two reaction channels under atmospherically relevant conditions.

  17. Retinoic acid isomers facilitate apolipoprotein E production and lipidation in astrocytes through the retinoid X receptor/retinoic acid receptor pathway.

    PubMed

    Zhao, Jing; Fu, Yuan; Liu, Chia-Chen; Shinohara, Mitsuru; Nielsen, Henrietta M; Dong, Qiang; Kanekiyo, Takahisa; Bu, Guojun

    2014-04-18

    Apolipoprotein E (apoE) is the major cholesterol transport protein in the brain. Among the three human APOE alleles (APOE2, APOE3, and APOE4), APOE4 is the strongest genetic risk factor for late-onset Alzheimer disease (AD). The accumulation of amyloid-β (Aβ) is a central event in AD pathogenesis. Increasing evidence demonstrates that apoE isoforms differentially regulate AD-related pathways through both Aβ-dependent and -independent mechanisms; therefore, modulating apoE secretion, lipidation, and function might be an attractive approach for AD therapy. We performed a drug screen for compounds that modulate apoE production in immortalized astrocytes derived from apoE3-targeted replacement mice. Here, we report that retinoic acid (RA) isomers, including all-trans-RA, 9-cis-RA, and 13-cis-RA, significantly increase apoE secretion to ~4-fold of control through retinoid X receptor (RXR) and RA receptor. These effects on modulating apoE are comparable with the effects recently reported for the RXR agonist bexarotene. Furthermore, all of these compounds increased the expression of the cholesterol transporter ABCA1 and ABCG1 levels and decreased cellular uptake of Aβ in an apoE-dependent manner. Both bexarotene and 9-cis-RA promote the lipidation status of apoE, in which 9-cis-RA promotes a stronger effect and exhibits less cytotoxicity compared with bexarotene. Importantly, we showed that oral administration of bexarotene and 9-cis-RA significantly increases apoE, ABCA1, and ABCG1 levels in mouse brains. Taken together, our results demonstrate that RXR/RA receptor agonists, including several RA isomers, are effective modulators of apoE secretion and lipidation and may be explored as potential drugs for AD therapy. PMID:24599963

  18. Isolation and Characterization of Two Geometric Allene Oxide Isomers Synthesized from 9S-Hydroperoxylinoleic Acid by Cytochrome P450 CYP74C3

    PubMed Central

    Brash, Alan R.; Boeglin, William E.; Stec, Donald F.; Voehler, Markus; Schneider, Claus; Cha, Jin K.

    2013-01-01

    Specialized cytochromes P450 or catalase-related hemoproteins transform fatty acid hydroperoxides to allene oxides, highly reactive epoxides leading to cyclopentenones and other products. The stereochemistry of the natural allene oxides is incompletely defined, as are the structural features required for their cyclization. We investigated the transformation of 9S-hydroperoxylinoleic acid with the allene oxide synthase CYP74C3, a reported reaction that unexpectedly produces an allene oxide-derived cyclopentenone. Using biphasic reaction conditions at 0 °C, we isolated the initial products and separated two allene oxide isomers by HPLC at −15 °C. One matched previously described allene oxides in its UV spectrum (λmax 236 nm) and NMR spectrum (defining a 9,10-epoxy-octadec-10,12Z-dienoate). The second was a novel stereoisomer (UV λmax 239 nm) with distinctive NMR chemical shifts. Comparison of NOE interactions of the epoxy proton at C9 in the two allene oxides (and the equivalent NOE experiment in 12,13-epoxy allene oxides) allowed assignment at the isomeric C10 epoxy-ene carbon as Z in the new isomer and the E configuration in all previously characterized allene oxides. The novel 10Z isomer spontaneously formed a cis-cyclopentenone at room temperature in hexane. These results explain the origin of the cyclopentenone, provide insights into the mechanisms of allene oxide cyclization, and define the double bond geometry in naturally occurring allene oxides. PMID:23709224

  19. Formation of the syn isomer of [Fe(IV)(Oanti)(TMC)(NCMe)](2+) in the reaction of Lewis acids with the side-on bound peroxo ligand in [Fe(III)(η(2)-O2)(TMC)](.).

    PubMed

    Prakash, Jai; Que, Lawrence

    2016-06-21

    We demonstrate that the reactions of [Fe(III)(η(2)-O2)(TMC)](+) (TMC = tetramethylcyclam) with Lewis acids (H(+) and NO(+)) afford the recently described syn isomer of [Fe(IV)(O)(TMC)(NCMe)](2+) (and not the anti isomer as had been tacitly assumed). This outcome is a logical consequence of the fact that the side-on peroxo ligand is bound to the syn face of the Fe(TMC) unit in the precursor. PMID:27273175

  20. Abundances of Triacylglycerol Positional Isomers and Enantiomers Comprised of a Dipalmitoylglycerol Backbone and Short- or Medium-chain Fatty Acids in Bovine Milk Fat.

    PubMed

    Nagai, Toshiharu; Watanabe, Natsuko; Yoshinaga, Kazuaki; Mizobe, Hoyo; Kojima, Koichi; Kuroda, Ikuma; Odanaka, Yuki; Saito, Tadao; Beppu, Fumiaki; Gotoh, Naohiro

    2015-01-01

    Bovine milk fat (BMF) is composed of triacylglycerols (TAG) rich in palmitic acid (P), oleic acid (O), and short-chain or medium-chain fatty acids (SCFAs or MCFAs). The composition and binding positions of the fatty acids on the glycerol backbone determine their physical and nutritional properties. SCFAs and MCFAs are known to characteristically bind to the sn-3 position of the TAGs in BMF; however, there are very few non-destructive analyses of TAG enantiomers binding the fatty acids at this position. We previously reported a method to resolve the enantiomers of TAGs, binding both long-chain saturated fatty acid and unsaturated fatty acid at the sn-1 and 3 positions, in palm oil, fish oil, and marine mammal oil using chiral HPLC. Here, we further developed a method to resolve several TAG enantiomers containing a dipalmitoyl (PP) glycerol backbone and one SCFA (or MCFA) in BMF. We revealed that the predominant TAG structure in BMF was homochiral, such as 1,2-dipalmitoyl-3-butyroyl-sn-glycerol. This is the first quantitative determination of many TAG enantiomers, which bind to a SCFA or MCFA, in BMF was evaluated simultaneously. Furthermore, the results indicated that the amount ratios of the positional isomers and enantiomers of TAGs consisting of a dipalmitoyl (PP) glycerol backbone and SCFA (or MCFA), resembled the whole TAG structures containing the other diacylglycerol backbones consisting of P, O, myristic acid, and/or stearic acid in BMF. PMID:26329769

  1. High-Throughput Analysis of Methylmalonic Acid in Serum, Plasma, and Urine by LC-MS/MS. Method for Analyzing Isomers Without Chromatographic Separation.

    PubMed

    Kushnir, Mark M; Nelson, Gordon J; Frank, Elizabeth L; Rockwood, Alan L

    2016-01-01

    Measurement of methylmalonic acid (MMA) plays an important role in the diagnosis of vitamin B12 deficiency. Vitamin B12 is an essential cofactor for the enzymatic carbon rearrangement of methylmalonyl-CoA (MMA-CoA) to succinyl-CoA (SA-CoA), and the lack of vitamin B12 leads to elevated concentrations of MMA. Presence of succinic acid (SA) complicates the analysis because mass spectra of MMA and SA are indistinguishable, when analyzed in negative ion mode and the peaks are difficult to resolve chromatographically. We developed a method for the selective analysis of MMA that exploits the significant difference in fragmentation patterns of di-butyl derivatives of the isomers MMA and SA in a tandem mass spectrometer when analyzed in positive ion mode. Tandem mass spectra of di-butyl derivatives of MMA and SA are very distinct; this allows selective analysis of MMA in the presence of SA. The instrumental analysis is performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) in positive ion mode, which is, in combination with selective extraction of acidic compounds, is highly selective for organic acids with multiple carboxyl groups (dicarboxylic, tricarboxylic, etc.). In this method organic acids with a single carboxyl group are virtually undetectable in the mass spectrometer; the only organic acid, other than MMA, that is detected by this method is its isomer, SA. Quantitative measurement of MMA in this method is performed using a deconvolution algorithm, which mathematically resolves the signal corresponding to MMA and does not require chromatographic resolution of the MMA and SA peaks. Because of its high selectivity, the method utilizes isocratic chromatographic separation; reconditioning and re-equilibration of the chromatographic column between injections is unnecessary. The above features of the method allow high-throughput analysis of MMA with analysis cycle time of 1 min. PMID:26602128

  2. Moderate doses of conjugated linoleic acid isomers mix contribute to lowering body fat content maintaining insulin sensitivity and a noninflammatory pattern in adipose tissue in mice.

    PubMed

    Parra, Pilar; Serra, Francisca; Palou, Andreu

    2010-02-01

    Conjugated linoleic acid (CLA) modulates body composition, especially by reducing adipose tissue. However, despite the increasing knowledge about CLA's beneficial effects on obesity management, the mechanism of action is not yet fully understood. Furthermore, in some human studies fat loss is accompanied by impairment in insulin sensitivity, especially when using the trans-10,cis-12 isomer. The aim of this work was to study the effects of moderate doses of CLA on body fat deposition, cytokine profile and inflammatory markers in mice. Mice were orally treated with a mixture of CLA isomers, cis-9,trans-11 and trans-10,cis-12 (50:50), for 35 days with doses of CLA1 (0.15 g CLA/kg body weight) and CLA2 (0.5 g CLA/kg body weight). CLA had discrete effects on body weight but caused a clear reduction in fat mass (retroperitoneal and mesenteric as the most sensitive depots), although no other tissue weights were affected. Glucose and insulin were not altered by CLA treatment, and maintenance of glucose homeostasis was observed even under insulin overload. The study of gene expression (Emr1, MCP-1, IL-6, TNFalpha, PPARgamma2 and iNOS) either in adipocytes and/or in the stromal vascular fraction indicated that CLA does not lead to the infiltration of macrophages in adipose tissue or to the induction of expression of pro-inflammatory cytokines. The use of a mixture of both isomers, as well as moderate doses of CLA, is able to induce a reduction of fat gain without an impairment of adipose tissue function while preserving insulin sensitivity. PMID:19195867

  3. New CE-ESI-MS analytical method for the separation, identification and quantification of seven phenolic acids including three isomer compounds in virgin olive oil.

    PubMed

    Nevado, Juan José Berzas; Peñalvo, Gregorio Castañeda; Robledo, Virginia Rodríguez; Martínez, Gabriela Vargas

    2009-10-15

    A sensitive and expeditious CE-ESI-MS analytical method for the separation, identification and determination of seven selected antioxidants (cinnamic and benzoic acids), including three isomers of coumaric acid (ortho-, meta- and para-) has been developed. In order to obtain the analytical separation, capillary electrophoresis and CE-MS interface parameters (e.g., buffer pH and composition, sheath liquid and gas flow rates, sheath liquid composition, electrospray voltage, etc.) were carefully optimized. The polar fraction containing the selected phenolic acids was obtained using a previously optimized SPE pretreatment. An MS detector in order to extract structural information about the target compounds and facilitate their qualitative analysis was used in the negative ion mode. The proposed off-line SPE CE-ESI-MS method was validated by assessing its precision, LODs and LOQs, linearity range and accuracy. The optimized and validated method was used in order to quantify the selected antioxidants in various samples of virgin olive oil and extra-virgin olive oil obtained from the main olive varieties cropped in Castilla-La Mancha, Spain. Salicylic acid was used as internal standard throughout in order to ensure reproducibility in the quantitative analysis of the oil samples. The results confirmed the presence of hydroxyphenyl acetic, p-coumaric, ferulic and vanillic acids in substantial amounts (microg g(-1) level) in all samples. PMID:19635353

  4. Dachtal Isomers and Acidic Herbicides and Pesticides in Eggs of Osprey (Pandion haliaetus) from the Seattle and Everett Areas, Washington, U.S.A

    USGS Publications Warehouse

    Chu, S.; Henny, Charles J.; Kaiser, James L.; Drouillard, K.G.; Haffner, G.D.; Letcher, R.J.

    2007-01-01

    Current-use chlorophenoxy herbicides including 2,4-dichlorophenoxyacetic acid, dicamba, triclopyr, dicamba, dimethyl tetrachloroterephthalate (DCPA or dacthal), and the metabolite of pyrethroids, 3-phenoxybenzoic acid (3-PBA), and the fungicide, chlorothalonil, were investigated in the eggs of osprey (Pandion haliaetus) that were collected from 15 sites from five study areas Puget Sound/Seattle area of Washington State, USA. DCPA differs from acidic chlorophenoxy herbicides, and is not readily hydrolyzed to free acid or acid metabolites, and thus we developed a new method. Of the 12 chlorophenoxy herbicides and chlorothalonil analyzed only DCPA could be quantified at six of these sites (2.0 to 10.3 pg/g fresh weight). However, higher levels (6.9 to 85.5 pg/g fresh weight) of the unexpected DCPA structural isomer, dimethyl tetrachlorophthalate (diMe-TCP) were quantified in eggs from all sites. diMe-TCP concentrations tended to be higher in eggs from the Everett Harbor area. As diMe-TCP is not an industrial product, and not commercially available, the source of diMe-TCP is unclear. Regardless, these findings indicate that DCPA and diMe-TCP can be accumulated in the food chain of fish-eating osprey, and transferred in ovo to eggs, and thus may be of concern to the health of the developing chick and the general reproductive health of this osprey population.

  5. Influence of Vaginal Bacteria and d- and l-Lactic Acid Isomers on Vaginal Extracellular Matrix Metalloproteinase Inducer: Implications for Protection against Upper Genital Tract Infections

    PubMed Central

    Witkin, Steven S.; Mendes-Soares, Helena; Linhares, Iara M.; Jayaram, Aswathi; Ledger, William J.; Forney, Larry J.

    2013-01-01

    ABSTRACT We evaluated levels of vaginal extracellular matrix metalloproteinase inducer (EMMPRIN) and matrix metalloproteinase (MMP-8) in vaginal secretions in relation to the composition of vaginal bacterial communities and d- and l-lactic acid levels. The composition of vaginal bacterial communities in 46 women was determined by pyrosequencing the V1 to V3 region of 16S rRNA genes. Lactobacilli were dominant in 71.3% of the women, followed by Gardnerella (17.4%), Streptococcus (8.7%), and Enterococcus (2.2%). Of the lactobacillus-dominated communities, 51.5% were dominated by Lactobacillus crispatus, 36.4% by Lactobacillus iners, and 6.1% each by Lactobacillus gasseri and Lactobacillus jensenii. Concentrations of l-lactic acid were slightly higher in lactobacillus-dominated vaginal samples, but most differences were not statistically significant. d-Lactic acid levels were higher in samples containing L. crispatus than in those with L. iners (P < 0.0001) or Gardnerella (P = 0.0002). The relative proportion of d-lactic acid in vaginal communities dominated by species of lactobacilli was in concordance with the proportions found in axenic cultures of the various species grown in vitro. Levels of l-lactic acid (P < 0.0001) and the ratio of l-lactic acid to d-lactic acid (P = 0.0060), but not concentrations of d-lactic acid, were also correlated with EMMPRIN concentrations. Moreover, vaginal concentrations of EMMPRIN and MMP-8 levels were highly correlated (P < 0.0001). Taken together, the data suggest the relative proportion of l- to d-lactic acid isomers in the vagina may influence the extent of local EMMPRIN production and subsequent induction of MMP-8. The expression of these proteins may help determine the ability of bacteria to transverse the cervix and initiate upper genital tract infections. PMID:23919998

  6. Identification of the oleic acid ethanolamide (OEA) isomer cis-vaccenic acid ethanolamide (VEA) as a highly abundant 18:1 fatty acid ethanolamide in blood plasma from rats and humans.

    PubMed

    Röhrig, Waldemar; Waibel, Reiner; Perlwitz, Christopher; Pischetsrieder, Monika; Hoch, Tobias

    2016-09-01

    The endocannabinoid system is important in various physiological pathways, especially the regulation of food intake. It consists of endocannabinoids like 2-arachidonoyl-glycerol (2-AG) or the fatty acid ethanolamide archachidonoyl-ethanolamide (AEA) with binding affinity to cannabinoid receptors. Further, fatty acid ethanolamides (FAEAs) influence the endocannabinoid system without affecting cannabinoid receptors by using independent physiological pathways. Among FAEAs, oleic acid ethanolamide (OEA) gained importance because of its promising ability to reduce food intake. By ultrahigh-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UHPLC-ESI-MS/MS), we detected a chromatographically separated molecule in plasma samples from rats and humans with identical mass and fragmentation patterns as those of OEA. Via synthesis and extensive analysis of ethanolamides of different cis/trans- and position isomers of oleic acid (cis9-18:1), we could identify the unknown molecule as vaccenic acid (cis11-18:1) ethanolamide (VEA). In this study we identified VEA as the most abundant 18:1 FAEA in rat plasma and the second most abundant 18:1 FAEA in human plasma. PMID:27334716

  7. Comparative Evaluation of a New Endodontic Irrigant - Mixture of a Tetracycline Isomer, an Acid, and a Detergent to Remove the Intracanal Smear Layer: A Scanning Electron Microscopic Study

    PubMed Central

    Gupta, Poonam K; Mahajan, Uma Patil; Gupta, Kapil; Sheela, N V

    2015-01-01

    Background: The most important and demanding aspect of endodontic therapy is considered to be cleaning and shaping. Irrigation is considered a vital adjunct to instrumentation of the root canal for canal debridement. Until date, there is no single solution that simultaneously removes the smear layer and disinfects the entire root canal system. Thus, this in vitro study was designed to evaluate the efficiency of a new irrigation solution mixture of a tetracycline isomer, an acid, and a detergent (MTAD) (BioPure, Dentsply) containing a mixture of tetracycline (doxycycline hydrochloride), an acid (citric acid) and a detergent (Tween 80) in comparison with normal saline, 5% NaOCl and 17% ethylenediaminetetraacetic acid (EDTA) to remove intracanal smear layer. Materials and Methods: A total of 60 single rooted teeth were irrigated with Saline (Group A), 5% NaOCl (Group B), 17% EDTA (Group C) and MTDA (Group D). The extent of removal of smear layer and erosion was assessed using scanning electron microscope. Results: Irrigation with 5% NaOCl and MTAD as a final flush produced the cleanest surface with all the dentinal tubules open. No conjugation or erosion of dentinal tubules was noted (P > 0.05). Conclusion: MTAD flush was the most effective debridement regimen in all the three thirds of the canal showing its ability to reach the apex with no conjugation and erosion of dentinal tubules. PMID:25954062

  8. Development and Optimization of an UPLC-QTOF-MS/MS Method Based on an In-Source Collision Induced Dissociation Approach for Comprehensive Discrimination of Chlorogenic Acids Isomers from Momordica Plant Species

    PubMed Central

    Madala, N. E.; Tugizimana, F.; Steenkamp, P. A.

    2014-01-01

    Chlorogenic acids (CGA) have been profiled in the leaves of Momordica balsamina, Momordica charantia, and Momordica foetida. All three species were found to contain the trans and cis isomers of 4-acyl para-coumaroylquinic acid (pCoQA), caffeoylquinic acid (CQA), and feruloylquinic acid (FQA). To the best of our knowledge, this is the first report of pCoQA and FQA and their cis isomers in these Momordica species. These profiles were obtained by a newly developed UPLC-qTOF-MS method based on the in-source collision induced dissociation (ISCID) method optimized to mimic the MS2 and MS3 fragmentation of an ion trap-based MS. The presence of the cis isomers is believed to be due to high UV exposure of these plants. Furthermore, the absence of the 3-acyl and 5-acyl CGA molecules points to a metabolic mark that is unusual and represents a very interesting biochemical phenotype of these species. Our optimized ISCID method was also shown to be able to distinguish between the geometrical isomers of all three forms of CGA, a phenomenon previously deemed impossible with other common mass spectrometry systems used for CGA analyses. PMID:25295221

  9. High spin isomer beam line at RIKEN

    SciTech Connect

    Kishida, T.; Ideguchi, E.; Wu, H.Y.

    1996-12-31

    Nuclear high spin states have been the subject of extensive experimental and theoretical studies. For the production of high spin states, fusion reactions are usually used. The orbital angular momentum brought in the reaction is changed into the nuclear spin of the compound nucleus. However, the maximum induced angular momentum is limited in this mechanism by the maximum impact parameter of the fusion reaction and by the competition with fission reactions. It is, therefore, difficult to populate very high spin states, and as a result, large {gamma}-detector arrays have been developed in order to detect subtle signals from such very high spin states. The use of high spin isomers in the fusion reactions can break this limitation because the high spin isomers have their intrinsic angular momentum, which can bring the additional angular momentum without increasing the excitation energy. There are two methods to use the high spin isomers for secondary reactions: the use of the high spin isomers as a target and that as a beam. A high spin isomer target has already been developed and used for several experiments. But this method has an inevitable shortcoming that only {open_quotes}long-lived{close_quotes} isomers can be used for a target: {sup 178}Hf{sup m2} (16{sup +}) with a half-life of 31 years in the present case. By developing a high spin isomer beam, the authors can utilize various short-lived isomers with a short half-life around 1 {mu}s. The high spin isomer beam line of RIKEN Accelerator Facility is a unique apparatus in the world which provides a high spin isomer as a secondary beam. The combination of fusion-evaporation reaction and inverse kinematics are used to produce high spin isomer beams; in particular, the adoption of `inverse kinematics` is essential to use short-lived isomers as a beam.

  10. Analysis and Characterization of Trans Isomers by Silver-Ion HPLC

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Produced by the partial hydrogenation of vegetable oils and present in animal fats and selected seed oils, trans fatty acids [both configurational (cis vs trans) and positional (double bond location may vary from the delta-4 to the delta-16 position on the fatty acid carbon chain) isomers continue t...

  11. A tandem mass spectrometric study of bile acids: interpretation of fragmentation pathways and differentiation of steroid isomers.

    PubMed

    Qiao, Xue; Ye, Min; Liu, Chun-fang; Yang, Wen-zhi; Miao, Wen-juan; Dong, Jing; Guo, De-an

    2012-02-01

    Bile acids are steroids with a pentanoic acid substituent at C-17. They are the terminal products of cholesterol excretion, and play critical physiological roles in human and animals. Bile acids are easy to detect but difficult to identify by using mass spectrometry due to their poly-ring structure and various hydroxylation patterns. In this study, fragmentation pathways of 18 free and conjugated bile acids were interpreted by using tandem mass spectrometry. The analyses were conducted on ion trap and triple quadrupole mass spectrometers. Upon collision-induced dissociation, the conjugated bile acids could cleave into glycine or taurine related fragments, together with the steroid skeleton. Fragmentations of free bile acids were further elucidated, especially by atmospheric pressure chemical ionization mass spectrometry in positive ion mode. Aside from universally observed neutral losses, eliminations occurred on bile acid carbon rings were proposed for the first time. Moreover, four isomeric 5β-cholanic acid hydroxyl derivatives (3α,6α-, 3α,7β-, 3α,7α-, and 3α,12α-) were differentiated using electrospray ionization in negative ion mode: 3α,7β-OH substituent inclined to eliminate H(2)O and CH(2)O(2) groups; 3α,6α-OH substituent preferred neutral loss of two H(2)O molecules; 3α,12α-OH substituent apt to lose the carboxyl in the form of CO(2) molecule; and 3α,7α-OH substituent exhibited no further fragmentation after dehydration. This study provided specific interpretation for mass spectra of bile acids. The results could contribute to bile acid analyses, especially in clinical assays and metabonomic studies. PMID:22133544

  12. Effect of trans fatty acid isomers from ruminant sources on risk factors of cardiovascular disease: study design and rationale

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Substantial evidence clearly demonstrates the deleterious effects of industrially-produced trans fatty acids (TFA); however, data are lacking from large, well-controlled human feeding studies that directly compare the effects of industrially-produced and naturally-occurring TFA. The purpose of the c...

  13. EFFECT OF DIETARY CLA ON METABOLISM OF ISOTOPE-LABELED OLEIC, LINOLEIC AND CONJUGATED LINOLEIC ACID ISOMERS IN WOMEN

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Animal studies suggest that conjugated linoleic acid (CLA) has potential health benefits, but no definitive metabolic data are available to support the possibility that it has physiological activity in humans. The purpose of this study was to determine the effect of dietary CLA on oleic, linoleic, ...

  14. E/Z Isomers and Isomerization

    NASA Astrophysics Data System (ADS)

    Liaaen-Jensen, Synnøve; Lutnœes, Bjart Frode

    The natural occurrence of several carotenoid cis isomers and their biological significance were not anticipated in 1962, when the classical monograph on cis-trans isomeric carotenoids [1] was published. More recent research has demonstrated that various cis isomers occur naturally in bacteria plants, algae and invertebrate animals, and are present in human blood and tissues. The participation of cis isomers in the biosynthethic route to coloured carotenoids is well established (Volume 3, Chapter 2). Important biological functions of (15Z)-carotenoids in photosynthesis have been revealed [2]. In relation to health aspects of carotenoids, the bioavailability of cis isomers may be higher than that of the all-trans isomer [3], and accumulated evidence suggests that cis/trans isomerization may occur in biological tissues, particularly of lycopene (31) in human serum [4] (Volume 5, Chapter 7).

  15. Impact of additives on thermally-induced trans isomers in 9c,12c linoleic acid triacylglycerol.

    PubMed

    Guo, Qin; Ha, Yiming; Li, Qingpeng; Jin, Jing; Deng, Zhaoxuan; Li, Yongfu; Zhang, Songshan

    2015-05-01

    Trilinolein, with or without additives, was placed in glass ampoules and subjected to thermal treatment at 180 °C or 240 °C for 8h. Thermal treatment of trilinolein at 180 °C and 240 °C produced twice the amount of trans nonconjugated linoleic acids (NLAs) compared to conjugated linoleic acids (CLAs), and nitrogen stream reduced the amount of both trans NLA and CLA products. The presence of additives resulted in the suppression or induction of trans NLAs and CLAs, depending on the type of additive, the concentration of the additive, and the heating temperature. Our analysis indicates that TBHQ is an effective additive for reducing trans NLA formation and inducing trans CLA formation in frying oil. Glutathione and L-cysteine at 0.1% may also be used as additives for frying oil. At suitable concentrations, Fe(3+) and Al(3+) ions derived from oils can reduce trans NLAs and induce trans CLAs during frying. PMID:25529684

  16. Synthesis of cationic single-isomer cyclodextrins for the chiral separation of amino acids and anionic pharmaceuticals.

    PubMed

    Tang, Weihua; Ng, Siu-Choon

    2007-01-01

    We describe a protocol for the synthesis of mono-6(A)-(1-butyl-3-imidazolium)-6(A)-deoxy-beta-cyclodextrin chloride (BIMCD), a cationic, water-soluble cyclodextrin used in the chiral separation of amino acids and anionic pharmaceuticals by capillary electrophoresis. Starting from commercially available chemicals, BIMCD is synthesized in five steps. The first step involves a nucleophilic substitution between p-toluenesulfonyl chloride and imidazole to afford 1-(p-toluenesulfonyl)imidazole (A). In the second step, a nucleophilic substitution between beta-cyclodextrin and A affords mono-6(A)-(p-toluenesulfonyl)-6(A)-deoxy-beta-cyclodextrin (B). In the third step, a nucleophilic substitution between 1-bromobutane and imidazole affords 1-butylimidazole (C). In the fourth step, a nucleophilic addition between A and C affords BIMCD tosylate. In the final step, anion exchange using an ion-exchange resin yields BIMCD as a highly water-soluble solid. Each step takes up to 2 d, including the time required for product purification. The overall protocol requires approximately 6 d. PMID:18079719

  17. A UV-light activated cinnamic acid isomer regulates plant growth and gravitropism via an ethylene receptor-independent pathway.

    PubMed

    Yang, X X; Choi, H W; Yang, S F; Li, N

    1999-01-01

    Naturally occurring cinnamic acids (CA) exist in both trans- and cis-isoforms. UV-light irradiation of trans-CA is able to produce cis-CA. cis-CA was found to possess auxin-like activity before. In contrast, the vapor of cis-CA induced an epinastic response in tomato plants just as ethylene does. Given the existence of a double bond in and the gaseous nature of cis-CA, we suspected that cis-CA might also function as an ethylene-like compound. To distinguish between these possibilities, we selected an ethylene perception-deficient tomato plant, Never-ripe (Nr), and an ethylene biosynthesis-deficient tomato plant, A11. Not only did the vapor of cis-CA fail to trigger A11 tomato fruit ripening but it also delayed the ripening of banana fruit. Moreover, the vapor of cis-CA induced epinasty and the 'triple response' in both the wild type and Nr tomato plants, indicating that the vapor of cis-CA does not act via an ethylene receptor-dependent pathway. Furthermore, the vapor of cis-CA inhibited the negative gravitropic response of stems of both etiolated Nr seedlings and young plants, whereas ethylene had little effect on the negative gravitropism of the Nr plants. These results support the conclusion that the action sites of the vapor of cis-CA and ethylene are fundamentally different. PMID:11542914

  18. [Ni(PPh2NBn2)2(CH3CN)]2+ as an Electrocatalyst for H2 Production: Dependence on Acid Strength and Isomer Distribution

    SciTech Connect

    Appel, Aaron M.; Pool, Douglas H.; O'Hagan, Molly J.; Shaw, Wendy J.; Yang, Jenny Y.; Rakowski DuBois, Mary; DuBois, Daniel L.; Bullock, R. Morris

    2011-07-01

    [Ni(PPh2NBz2)2(CH3CN)](BF4)2, Ni(PPh2NBz2)22+ (where PPh2NBz2 is 1,5-dibenzyl-3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane) has been studied as an electrocatalyst for the production of hydrogen in acetonitrile. Using strong acids, such as p cyanoanilinium, Ni(PPh2NBz2)22+ has been shown to be protonated under catalytic conditions prior to reduction, with an effective pKa of 6.7±0.4. Through multinuclear NMR spectroscopy studies, the nickel(II) complex was found to be doubly protonated without any observed singly protonated species. In the doubly protonated complex, both protons are positioned exo with respect to the metal center and are stabilized by an N-H-N hydrogen bond. The formation of exo protonated isomers is proposed to limit the rate of hydrogen production because the protons are unable to gain suitable proximity to the reduced metal center to generate dihydrogen. Pre-protonation of Ni(PPh2NBz2)22+ has been found to shift the catalytic operating potential to more positive potentials by up to 440 mV, depending upon the conditions. The catalytic rate was found to increase by an order of magnitude by increasing the solution pH or through the addition of water. This material is based upon work supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences.

  19. Ultrasensitive analysis of lysergic acid diethylamide and its C-8 isomer in hair by capillary zone electrophoresis in combination with a stacking technique and laser induced fluorescence detection.

    PubMed

    Airado-Rodríguez, Diego; Cruces-Blanco, Carmen; García-Campaña, Ana M

    2015-03-25

    This article deals with the development and validation of a novel capillary zone electrophoresis (CZE) with laser induced fluorescence detection method for the analysis of lysergic acid diethylamide (LSD) and its isomer iso-LSD in hair samples. The separation of both analytes has been achieved in less than 13 min in a 72-cm effective length capillary with 75-μm internal diameter. As running buffer 25 mM citrate, pH 6.0 has been employed and separation temperature and voltage of 20 °C and 13 kV respectively, were applied. Field amplified sample injection (FASI) has been employed for on-line sample preconcentration, using ultrapure water containing 117 μM H3PO4 as optimum injection medium. Injection voltage and time have been optimized by means of experimental design, obtaining values of 7 kV and 15s, respectively. Methylergonovine has been employed as internal standard in order to compensate irreproducibility from electrokinetic injection. The analytical method has been applied to hair samples, previous extraction of the target analytes by ultrasound assisted solid-liquid extraction at 40 °C for 2.5 h, employing acetonitrile as extracting solvent. Linear responses were found for LSD and iso-LSD in matrix-matched calibrations from around 0.400 up to 50.0 pg mg(-1). LODs (3 S/N) in the order of 0.100 pg mg(-1) were calculated for both analytes, obtaining satisfactory recovery percentages for this kind of sample. PMID:25732697

  20. The antiproliferative activity of all-trans-retinoic acid catabolites and isomers is differentially modulated by liarozole-fumarate in MCF-7 human breast cancer cells.

    PubMed Central

    Van heusden, J.; Wouters, W.; Ramaekers, F. C.; Krekels, M. D.; Dillen, L.; Borgers, M.; Smets, G.

    1998-01-01

    The clinical use of all-trans-retinoic acid (ATRA) in the treatment of cancer is significantly hampered by the prompt emergence of resistance, believed to be caused by increased ATRA catabolism. Inhibitors of ATRA catabolism may therefore prove valuable for cancer therapy. Liarozole-fumarate is an anti-tumour drug that inhibits the cytochrome P450-dependent catabolism of ATRA. ATRA, but also its naturally occurring catabolites, 4-oxo-ATRA and 5,6-epoxy-ATRA, as well as its stereoisomers, 9-cis-RA and 13-cis-RA, show significant antiproliferative activity in MCF-7 human breast cancer cells. To further elucidate its mechanism of action, we investigated whether liarozole-fumarate was able to enhance the antiproliferative activity of ATRA catabolites and isomers. Liarozole-fumarate alone up to a concentration of 10(-6) M had no effect on MCF-7 cell proliferation. However, in combination with ATRA or the ATRA catabolites, liarozole-fumarate (10(-6) M) significantly enhanced their antiproliferative activity. On the contrary, liarozole-fumarate (10(-6) M) was not able to potentiate the antiproliferative activity of the ATRA stereoisomers, most probably because of the absence of cytochrome P450-dependent catabolism. Together, these findings show that liarozole-fumarate acts as a versatile inhibitor of retinoid catabolism in that it not only blocks the breakdown of ATRA, but also inhibits the catabolic pathway of 4-oxo-ATRA and 5,6-epoxy-ATRA, thereby enhancing their antiproliferative activity. PMID:9579827

  1. Using One's Hands for Naming Optical Isomers and Other Stereochemical Positions.

    ERIC Educational Resources Information Center

    Mezl, Vasek A.

    1996-01-01

    Presents a method that allows students to use their hands to obtain the stereochemistry of chiral centers without redrawing the structure. Discusses the use of the model in: determining the configurations of amino acids, determining if sugars are D or L isomers, the sequence rule procedure, prochirality, naming the sides of trigonal carbons, and…

  2. Rapeseed or linseed in grass-based diets: effects on conjugated linoleic and conjugated linolenic acid isomers in milk fat from Holstein cows over 2 consecutive lactations.

    PubMed

    Lerch, S; Shingfield, K J; Ferlay, A; Vanhatalo, A; Chilliard, Y

    2012-12-01

    Changes in the distribution of conjugated linoleic (CLA) and conjugated linolenic (CLnA) acid isomers in milk from Holstein cows in response to 4 different oilseed supplements rich in either cis-9 18:1 or 18:3n-3 were determined over 2 consecutive lactations in 58 and 35 cows during the first and second years, respectively. For the first 5 wk of the first lactation, all cows were fed the same diet. Thereafter, cows received 1 of 5 treatments for 2 consecutive lactations, including the prepartum period. Treatments comprised the basal diet with no additional lipid, or supplements of extruded linseeds (EL), extruded rapeseeds (ER), cold-pressed fat-rich rapeseed meal, or whole unprocessed rapeseeds to provide 2.5 to 3.0% of additional oil in diet dry matter. During indoor periods, cows were housed and received a mixture (3:1, wt/wt) of grass silage and hay, whereas cows were at pasture during outdoor periods. Over the entire study, EL resulted in the enrichment of ∆11,13 CLA, ∆12,14 CLA, trans-9,trans-11 CLA, trans-13,trans-15 CLA, ∆9,11,15 CLnA, and cis-9,trans-11,trans-13 CLnA (identified for the first time in bovine milk fat) in milk fat, whereas ER and cold-pressed fat-rich rapeseed meal in particular, increased milk fat trans-7,cis-9 CLA concentration. With the exception of the first indoor period, whole unprocessed rapeseeds decreased cis-9,trans-11 CLA, trans-9,cis-11 CLA, and trans-10,trans-12 CLA abundance. During the second indoor period, EL increased milk trans-9,cis-11 CLA and trans-10,cis-12 CLA concentrations, but the increases in cis-9,trans-11 CLA, cis-12,trans-14 CLA, trans-11,cis-13 CLA, and cis-9,trans-11,cis-15 CLnA concentrations to EL and ER were lower for the second than first indoor period. In contrast to the indoor periods, EL and ER decreased milk cis-9,trans-11 CLA, trans-9,cis-11 CLA, and trans-10,cis-12 CLA concentrations at pasture. The extent of changes in the relative distribution and abundance of CLA and CLnA isomers in milk fat

  3. Dietary trans fatty acid isomers differ in their effects on mammary lipid metabolism as well as lipogenic gene expression in lactating mice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objectives were to examine the effects of several individual trans-18:1 isomers and t10c12-CLA on fat synthesis, and expression of lipogenic genes and transcription factors in liver and mammary tissues in lactating mice. Thirty lactating C57Bl6J mice were randomly assigned to 6 diets supplement...

  4. Preparation of 3R- and 3S-methyl isomers of the myocardial imaging agent 15-(p-IODOPHENYL)-3-methylpentadecanoic acid ({open_quotes}BMIPP{close_quotes})

    SciTech Connect

    Lin, Q. |; Luo, J.; Mokler, F.

    1996-10-01

    Iodine-123-labeled racemic BMIPP is used for clinical evaluation of heart disease. To evaluate the expected importance of configuration of the asymmetric C-3 center, we have synthesized the 3R-isomer. 6-Phenylhexanoyl chloride was condensed with thiophene (Friedel-Crafts), followed by Wolff-Kishner reduction and subsequent acylation with the ethyl-3-R-methylglutaroyl chloride, Wolff-Kishner reduction and Raney-Ni ring opening. Para Thallation (TTFA)/KI provided 3R-BMIPP, m.p. 51-52{degrees}C, [{alpha}{sub D}] = +0.74{degrees}. The diastereomeric amide mixture was prepared by reaction of racemic 3-R,S-BMIPP with (S)-(-)-{alpha}-methylbenzylamine. Chromatographic separation and HCl hydrolysis (at 175{degrees}C) provided the 3R- and 3S- (m.p. 45-46{degrees}C, [{alpha}{sub D}] = -1.67{degrees}) BMIPP isomers. The more polar amide (m.p. 93-94{degrees}C) was identical with the amide from the synthetic 3R-BMIPP (m.p., HPLC, NMR). Availability of the 3R- and 3S-BMIPP isomers will permit preparation of the radioiodinated isomers and animal evaluation to determine the effects of the methyl group configuration on myocardial uptake and metabolism.

  5. Vaccenic acid and trans fatty acid isomers from partially hydrogenated oil both adversely affect LDL cholesterol: a double-blind, randomized controlled trial

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Evidence of the adverse effects of industrially-produced trans fatty acids (iTFA) on risk of cardiovascular disease is consistent and well documented in the scientific literature; however, the cardiovascular effects of naturally-occurring TFA synthesized in ruminant animals (rTFA), such as vaccenic ...

  6. Energetic and Structural Study of Diphenylpyridine Isomers

    NASA Astrophysics Data System (ADS)

    Rocha, Marisa A. A.; Gomes, Lígia R.; Low, John N.; Santos, Luís M. N. B. F.

    2009-09-01

    The energetic and structural study of three diphenylpyridine isomers is presented in detail. The three isomers, 2,6-, 2,5-, and 3,5-diphenylpyridines, were synthesized via Suzuki-Miyaura methodology based on palladium catalysis, and the crystal structures of the isomers were obtained by X-ray diffraction. The relative energetic stabilities in the condensed and gaseous phases as well as volatilities and structures of the three studied isomers were evaluated, regarding the position of the phenyl groups relative to the nitrogen atom of the pyridine ring. The temperature, standard molar enthalpies, and entropies of fusion were measured and derived by differential scanning calorimetry. The vapor pressures of the considered isomers were determined by a static apparatus based on a MKS capacitance diaphragm manometer. The standard molar enthalpies, entropies, and Gibbs energies of sublimation, at T = 298.15 K, were derived, and the phase diagram near the triple point coordinates were determined for all isomers. The standard (p° = 0.1 MPa) molar enthalpies of combustion of all crystalline isomers were determined, at T = 298.15 K, by static bomb combustion calorimetry. The standard molar enthalpies of formation, in the crystalline and gaseous phases, at T = 298.15 K, were derived. The experimental results for the energetics in the gaseous phase of the three compounds were compared and assessed with the values obtained by ab initio calculations at different levels of theory (DFT and MP2) showing that, at this level of theory, the computational methods underestimate the energetic stability, in the gaseous phase, for these molecules. In order to understand the aromaticity in the central ring of each isomer, calculations of NICS (B3LYP/6-311G++(d,p) level of theory) values on the pyridine ring were also performed.

  7. The interstellar chemistry of H2C3O isomers

    NASA Astrophysics Data System (ADS)

    Loison, Jean-Christophe; Agúndez, Marcelino; Marcelino, Núria; Wakelam, Valentine; Hickson, Kevin M.; Cernicharo, José; Gerin, Maryvonne; Roueff, Evelyne; Guélin, Michel

    2016-03-01

    We present the detection of two H2C3O isomers, propynal and cyclopropenone, toward various starless cores and molecular clouds, together with upper limits for the third isomer propadienone. We review the processes controlling the abundances of H2C3O isomers in interstellar media showing that the reactions involved are gas-phase ones. We show that the abundances of these species are controlled by kinetic rather than thermodynamic effects.

  8. The interstellar chemistry of H2C3O isomers

    PubMed Central

    Loison, Jean-Christophe; Agúndez, Marcelino; Marcelino, Núria; Wakelam, Valentine; Hickson, Kevin M.; Cernicharo, José; Gerin, Maryvonne; Roueff, Evelyne; Guélin, Michel

    2016-01-01

    We present the detection of two H2C3O isomers, propynal and cyclopropenone, toward various starless cores and molecular clouds, together with upper limits for the third isomer propadienone. We review the processes controlling the abundances of H2C3O isomers in interstellar media showing that the reactions involved are gas-phase ones. We show that the abundances of these species are controlled by kinetic rather than thermodynamic effects. PMID:27013768

  9. Simultaneous ozonation kinetics of phenolic acids present in wastewaters

    SciTech Connect

    Benitez, F.J.; Beltran-Heredia, J.; Acero, J.L.; Pinilla, M.L.

    1996-12-31

    Among the several chemical processes conducted for the removal of organic matter present in wastewaters coming from some agro-industrial plants (wine distilleries, olive oil mills, etc), the oxidation by ozone has shown a great effectiveness in the destruction of specially refractory pollutants: it is demonstrated that the biodegradability of those wastewaters increases aflcer an ozonation pretreatment. Their great pollutant character is imputed to the presence of some organic compounds, like phenols and polyphenols, which are toxic and inhibit the latter biological treatments. In this research, a competitive kinetic procedure reported by Clurol and Nekouinaini is applied to determine the degradation rate constants by ozone of several phenolic acids which are present in the wastewaters from the olive oil obtaining process. The resulting kinetic expressions for the ozonation reactions are useful for the successful design and operation of ozone reactors in water and wastewaters treatment plants.

  10. Arachidonic acid needed in infant formula when docosahexaenoic acid is present.

    PubMed

    Brenna, J Thomas

    2016-05-01

    Recently, the European Food Safety Authority asserted that arachidonic acid (ARA) is an optional nutrient for the term infant even when docosahexaenoic acid (DHA) is present. The brief rationale is based on an explicit, widespread misapplication of the concept of "essential fatty acids" to linoleic acid that implies it is uniquely required as a nutrient per se. Linoleic acid prevents acute clinical symptoms caused by polyunsaturated fatty acid-deficient diets and is the major precursor for ARA in most human diets. Experimental diets with ARA as the sole n-6 similarly prevent symptoms but at a lower energy percentage than linoleic acid and show ARA is a precursor for linoleic acid. The absence of consistent evidence of ARA benefit from randomized controlled trials is apparently an issue as well. This review highlights basic and clinical research relevant to ARA requirements as an adjunct to DHA in infancy. ARA is a major structural central nervous system component, where it rapidly accumulates perinatally and is required for signaling. Tracer studies show that ARA-fed infants derive about half of their total body ARA from dietary preformed ARA. Clinically, of the 3 cohorts of term infants studied with designs isolating the effects of ARA (DHA-only vs DHA+ARA), none considered ARA-specific outcomes such as vascular or immune function; the study with the highest ARA level showed significant neurocognitive benefit. All breastfed term infants of adequately nourished mothers consume both DHA and ARA. The burden of proof to substantially deviate from the composition of breastmilk is greater than that available from inherently empirical human randomized controlled trial evidence. Infant formulas with DHA but without ARA risk harm from suppression of ARA-mediated metabolism manifest among the many unstudied functions of ARA. PMID:27013482

  11. Stereospecific Synthesis of the Geometrical Isomers of a Natural Product

    ERIC Educational Resources Information Center

    Grove, T.; DiLella, D.; Volker, E.

    2006-01-01

    Stereospecific synthesis of a geometrical isomer is not a common topic for the introductory organic chemistry laboratory. We have developed and tested an experiment for the synthesis of (Z) and (E) isomers that has been performed successfully by undergraduate students. The experiment is presented to the students as a puzzle in which they must…

  12. Diagnostic fragment-ion-based and extension strategy coupled to DFIs intensity analysis for identification of chlorogenic acids isomers in Flos Lonicerae Japonicae by HPLC-ESI-MS(n).

    PubMed

    Zhang, Jia-Yu; Zhang, Qian; Li, Ning; Wang, Zi-Jian; Lu, Jian-Qiu; Qiao, Yan-Jiang

    2013-01-30

    A method of modified diagnostic fragment-ion-based extension strategy (DFIBES) coupled to DFIs (diagnostic fragmentation ions) intensity analysis was successfully established to simultaneously screen and identify the chlorogenic acids (CGAs) in Flos Lonicerae Japonicae (FLJ) by HPLC-ESI-MS(n). DFIs, such as m/z 191 [quinic acid-H](-), m/z 179 [caffeic acid-H](-) and m/z 173 [quinic acid-H-H2O](-) were determined or proposed from the fragmentation patterns analysis of corresponding reference substances for every chemical family of CGAs. A "structure extension" method was then proposed based on the well-demonstrated fragmentation patterns and was successively applied into the rapid screening of CGAs in FLJ. Considering that substitution isomerism is a common phenomenon, a full ESI-MS(n) fragmentation analysis according to the intensity of DFIs has been performed to identify the CGA isomers. Based on the DFIs and intensity analysis, 41 peaks attributed to CGAs including 4 caffeoylquinic acids (CQA), 7 CQA glycosides, 6 dicaffeoylquinic acids (DiCQA), 10 DiCQA glycosides, 1 tricaffeoylquinic acids (TriCQA), 4p-coumaroylquinic acids (pCoQA), 3 feruloylquinic acids (FQA) and 6 caffeoylferuloylquinic acids (CFQA) were identified preliminarily in a 65-min chromatographic run. It was the first time to systematically report the presence of CGAs in FLJ, especially for CQA glycosides, DiCQA glycosides, TriCQA, pCoQA and CFQA. All the results indicated that the method of developed DFIBES coupled to DFIs analysis was feasible, reliable and universal for screening and identifying the constituents with the same carbon skeletons especially the isomeric compounds from the complex extract of TCMs. PMID:23597880

  13. Separation of glyceride positional isomers by silver ion chromatography.

    PubMed

    Févrie, P; Bine, A; Dufossé, L; Grée, R; Yvergnaux, F

    2001-07-20

    Separation of triglyceride and diglyceride positional isomers by silver ion high-performance liquid chromatography coupled with an evaporative light-scattering detector is described. The triglyceride isomers had a fatty acid composition of CLC and CCL, where C and L were caprylic acid and linoleic acid, respectively. Diglyceride isomers, 1,2(2,3)-diglyceride and 1,3-diglyceride, which contained caprylic acid were separated too. A solvent system based on n-hexane, 2-propanol, ethyl acetate, and acetonitrile with a flow-rate of 0.8 ml/min was developed. Calibration curves of CLC and CCL were achieved with triolein as internal standard. Using this method, the incorporation of linoleic acid onto specific a position of glycerol backbone can be monitored. PMID:11510559

  14. Polymerization of the E and Z Isomers of Bis-(Triethoxysilyl)-2-Butene

    SciTech Connect

    Carpenter, J.P. Dorhout, K.; Loy, D.A.; Shaltout, R.M.; Shea, K.J.

    1999-05-11

    We have synthesized the Z and E isomers of 1,4-bis(triethoxysilyl)-2- butene and polymerized them under acid and base catalyzed sol-gel conditions. As expected the E system formed crosslinked, insoluble gels. The Z isomer, by nature of its geometry, formed high molecular weight, soluble polymeric products under acidic conditions. We were able to prepare and isolate both the cyclic disilsesquioxane monomer, and its dimer. Comparison of their spectral characterization with that of the soluble polymers suggests that the cyclics are present within the polymers. lle synthesis of a dimer likely present at some early stage of the polymerization suggests that we may be able to control the reaction and form rigid polymers with controllable tacticity. In addition, most of the gels were found to be non-porous indicating that the gels were, in fact, more compliant than ethenylene-bridged polysilsesquioxanes leading to collapse of pores during drying.

  15. Comparison of suppression of mutagenicity of benzo(a)pyrene among methylsulfonyl polychlorinated biphenyl isomers

    SciTech Connect

    Kiyohara, Chikako; Hirohata, Tomio; Omura, Minoru; Masuda, Yoshito

    1992-06-01

    Methylsulfonyl (MSF) derivatives of polychlorinated biphenyls (PCBs) were first identified in fat from seals in the Baltic. Since then, a number of these substances have been demonstrated in animals. They were also isolated from the excreta of mice and rats treated with tri-, tetra-, penta- or hexachlorobiphenyls. Studies on the metabolic fates of several structurally defined chlorobiphenyls in mice showed that, in addition to the hydroxy species that were considered to be major metabolites of PCBs, sulfur-containing compounds were formed by the mercapturic acid pathway from PCB arene oxide. The accumulations of some MSF-PCB isomers have been evidenced not only in the mice experimentally ingested with certain PCBs but also in a human being accidentally exposed to PCBs. Even health people were found to have MSF-PCB isomers at concentrations as high as those of PCBs. It is noteworthy that some MSF-PCB isomers have been demonstrated to be toxic for rats and mice. Moreover, our preliminary study indicated that some MSF-PCB isomers have an inhibitory potency against the aryl hydrocarbon hydroxylase (AHH) activity, a well-known drug-metabolizing enzyme, in cultured human lymphoblastoid cells. These effects of MSF-PCB isomers seemed comparable to those of the well known 7,8-benzoflavone (7,8-BF), which inhibits chemical carcinogenesis. In the present study, we studied the effect of 11 MSF-PCB isomers and 7,8-BF on the mutagenicity of benzo(a)pyrene (BP) using Salmonella strains TA98 and TA100 in the Ames assay. In addition, the relationship between the results of Ames assay and the AHH assay was investigated. 17 refs., 3 tabs.

  16. Lewis acid adducts (BH sub 3 , Me sup + , and Et sup + ) of the. eta. sup 4 and. eta. sup 2 isomers of Cp sup * Ir(thiophene)

    SciTech Connect

    Chen, Jiabi; Angelici, R.J. )

    1990-03-01

    The {eta}{sup 4}-thiophene complex Cp{sup *}Ir({eta}{sup 4}-2,5-Me{sub 2}T) (2), where 2,5-Me{sub 2} is 2,5-dimethylthiophene, reacts with Me{sub 2}S{center dot}BH{sub 3} to give the BH{sub 3} adduct Cp{sup *}Ir({eta}{sup 4}-2,5-Me{sub 2}T{center dot}BH{sub 3}) (6), demonstrating the unusually high basicity of the sulfur in 2 as compared with that in Me{sub 2}S. Basic amines remove the BH{sub 3} in 6 to give 2. Surprisingly, the isomer Cp{sup *}Ir({eta}{sup 2}-2,5-Me{sub 2}T) (4) also reacts with Me{sub 2}S{center dot}BH to give 6. The 2-methylthiophene analogues of 2 and 4 react similarly to give Cp{sup *}Ir({eta}{sup 4}-2-MeT{center dot}BH{sub 3}) (5), whose structure was determined by X-ray diffraction. Complex 2 also reacts with R{sub 3}O{sup +} (R = Me, Et) to give the S-alkylated thiophene complexes Cp{sup *}Ir({eta}{sup 4}-2,5-Me{sub 2}T-R){sup +}.

  17. A glycoprotein binding retinoids and fatty acids is present in Drosophila.

    PubMed

    Duncan, T; Kutty, G; Chader, G J; Wiggert, B

    1994-07-01

    In the search for a possible Drosophila melanogaster homolog of interphotoreceptor retinoid-binding protein (IRBP), a approximately 140-kDa retinoid- and fatty acid-binding glycoprotein found in vertebrates, the 110,000 g supernatant fraction prepared from homogenates of fly heads was analyzed for the presence of proteins capable of binding radiolabeled retinol and palmitic acid. A soluble protein, which binds concanavalin A and has a retention time on size-exclusion high-performance liquid chromatography identical to that of purified bovine IRBP, was identified as binding both ligands. As assessed by fluorescence titration, the protein fraction obtained by concanavalin A-Sepharose affinity chromatography and size-exclusion chromatography of fly head supernatant had apparent dissociation constants of 2.9 x 10(-7) +/- 0.6 M for all-trans retinol, with the number (n) of independent ligand binding sites per protein molecule = 2, and 3.5 x 10(-7) +/- 0.1 M for 16-[9-anthroyloxy] palmitic acid with n = 7. High-performance liquid chromatography of hexane extracts of this protein fraction resolved several peaks with polarity and relative retention times similar, but not identical to all-trans retinol and retinal and their 9-, 11-, and 13-cis isomers. Gas chromatography/mass spectrometry analysis of fatty acid methyl esters prepared following lipid extraction of the protein identified lauric, myristic, palmitic, palmitoleic, and oleic acids as being covalently bound. Laurate, myristate, palmitate, and stearate were noncovalently bound. The apparent molecular mass of the Drosophila protein as assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and silver staining of the retinoid- and fatty acid-binding peak obtained by hydrophobic interaction chromatography of the size-exclusion fraction was approximately 70 kDa. PMID:8031123

  18. Aristolochic acid nephropathy: epidemiology, clinical presentation, and treatment.

    PubMed

    Luciano, Randy L; Perazella, Mark A

    2015-01-01

    Aristolochic acid (AA) is a compound extracted from the Aristolochia species of herbs. It has been used for centuries as a remedy for various illnesses and diseases. However, in the early 1990s in the setting of a weight loss herbal remedy, AA exposure was associated with a syndrome of kidney injury, termed aristolochic acid nephropathy (AAN). This entity is marked by elevated serum creatinine, significant anemia, and histopathologic changes demonstrating a hypocellular interstitial infiltrate with severe fibrosis. Progression towards end-stage renal disease (ESRD) is rapid, with most patients having chronic kidney disease for less than 2 years. In addition, AAN is associated with a 40-45 % prevalence of urothelial carcinomas. Treatment of AAN is limited to glucocorticoids that have been shown to delay progression in non-randomized trials. As most patients progress to ESRD, need for renal replacement therapy, as either dialysis or kidney transplant, usually ensues. However, given the high malignant potential, care must be taken to minimize future development of upper urinary tract cancers by performing prophylactic bilateral nephroureterectomies and aggressive cancer surveillance. PMID:25446374

  19. Fatty acid composition, including CLA's isomers and cholesterol content of m. longissimus lumborum and m. semimebranosus of Katahdin, Suffolk, Katahdin x Suffolk, and Suffolk x Katahdin lambs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Lipids in meat products have important human health implications. Muscle tissues from Katahdin (KK), Suffolk (SS), Katahdin x Suffolk (KS), and Suffolk x Katahdin (SS) lambs were analyzed to determine the effect of breed-type on muscle fatty acid composition, including conjugated linoleic acid (CLA)...

  20. Analysis of Triacylglycerol and Fatty Acid Isomers by Low-Temperature Silver-Ion High Performance Liquid Chromatography with Acetonitrile in Hexane as Solvent: Limitations of the Methodology

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Silver ion HPLC (Ag HPLC), utilizing columns containing silver ions bonded to a silica substrate and acetonitrile in hexane as solvent, has proven to be a powerful technology for the analysis of geometric (cis or trans) or positional fatty acids, fatty acid ester (primarily methyl ester; FAME), or t...

  1. Biodegradation of cresol isomers in anoxic aquifers.

    PubMed Central

    Smolenski, W J; Suflita, J M

    1987-01-01

    The biodegradation of o-, m-, and p-cresol was examined in material obtained from a shallow anaerobic alluvial sand aquifer. The cresol isomers were preferentially metabolized, with p-cresol being the most easily degraded. m-Cresol was more persistent than the para-isomer, and o-cresol persisted for over 90 days. Biodegradation of cresol isomers was favored under sulfate-reducing conditions (SRC) compared with that under methanogenic conditions (MC). Slurries that were acclimated to p-cresol metabolism transformed this substrate at 18 and 330 nmol/h per g (dry weight) for MC and SRC, respectively. Inhibition of electron flow to sulfate reduction with 2.0 mM molybdate reduced p-cresol metabolism in incubations containing sulfate. When methanogenesis was blocked with 5 mM bromoethanesulfonic acid in incubations lacking sulfate, p-cresol catabolism was retarded. Under SRC 3.4 mol of sulfate was consumed per mol of p-cresol metabolized. The addition of sulfate to methanogenic incubations stimulated p-cresol degradation. Simultaneous adaptation studies in combination with spectrophotometric and chromatographic analysis of metabolites indicated that p-cresol was oxidized under SRC to p-hydroxybenzoate via the corresponding alcohol and aldehyde. This series of reactions was inhibited under sulfate-limited or aerobic conditions. Therefore, the primary catabolic event for p-cresol decomposition under SRC appears to involve the hydroxylation of the aryl methyl group. PMID:3579279

  2. How are the Concepts and Theories of Acid Base Reactions Presented? Chemistry in Textbooks and as Presented by Teachers

    NASA Astrophysics Data System (ADS)

    Furió-Más, Carlos; Calatayud, María Luisa; Guisasola, Jenaro; Furió-Gómez, Cristina

    2005-09-01

    This paper investigates the views of science and scientific activity that can be found in chemistry textbooks and heard from teachers when acid base reactions are introduced to grade 12 and university chemistry students. First, the main macroscopic and microscopic conceptual models are developed. Second, we attempt to show how the existence of views of science in textbooks and of chemistry teachers contributes to an impoverished image of chemistry. A varied design has been elaborated to analyse some epistemological deficiencies in teaching acid base reactions. Textbooks have been analysed and teachers have been interviewed. The results obtained show that the teaching process does not emphasize the macroscopic presentation of acids and bases. Macroscopic and microscopic conceptual models involved in the explanation of acid base processes are mixed in textbooks and by teachers. Furthermore, the non-problematic introduction of concepts, such as the hydrolysis concept, and the linear, cumulative view of acid base theories (Arrhenius and Brönsted) were detected.

  3. Liquid Chromatography-Selected Reaction Monitoring (LC-SRM) Approach for the Separation and Quantitation of Sialylated N-Glycans Linkage Isomers

    PubMed Central

    2015-01-01

    The study of N-linked glycans is among the most challenging bioanalytical tasks because of their complexity and variety. The presence of glycoform families that differ only in branching and/or linkage position makes the identification and quantitation of individual glycans exceedingly difficult. Quantitation of these individual glycans is important because changes in the abundance of these isomers are often associated with significant biomedical events. For instance, previous studies have shown that the ratio of α2-3 to α2-6 linked sialic acid (SA) plays an important role in cancer biology. Consequently, quantitative methods to detect alterations in the ratios of glycans based on their SA linkages could serve as a diagnostic tool in oncology, yet traditional glycomic profiling cannot readily differentiate between these linkage isomers. Here, we present a liquid chromatography-selected reaction monitoring (LC-SRM) approach that we demonstrate is capable of quantitating the individual SA linkage isomers. The LC method is capable of separating sialylated N-glycan isomers differing in α2-3 and α2-6 linkages using a novel superficially porous particle (Fused-Core) Penta-HILIC (hydrophilic interaction liquid chromatography) column. SRM detection provides the relative quantitation of each SA linkage isomer, and minimizes interferences from coeluting glycans that are problematic for UV/Fluorescence based quantitation. With our approach, the relative quantitation of each SA linkage isomer is obtained from a straightforward liquid chromatography-mass spectrometry (LC-MS) experiment. PMID:25299151

  4. Liquid chromatography-selected reaction monitoring (LC-SRM) approach for the separation and quantitation of sialylated N-glycans linkage isomers.

    PubMed

    Tao, Shujuan; Huang, Yining; Boyes, Barry E; Orlando, Ron

    2014-11-01

    The study of N-linked glycans is among the most challenging bioanalytical tasks because of their complexity and variety. The presence of glycoform families that differ only in branching and/or linkage position makes the identification and quantitation of individual glycans exceedingly difficult. Quantitation of these individual glycans is important because changes in the abundance of these isomers are often associated with significant biomedical events. For instance, previous studies have shown that the ratio of α2-3 to α2-6 linked sialic acid (SA) plays an important role in cancer biology. Consequently, quantitative methods to detect alterations in the ratios of glycans based on their SA linkages could serve as a diagnostic tool in oncology, yet traditional glycomic profiling cannot readily differentiate between these linkage isomers. Here, we present a liquid chromatography-selected reaction monitoring (LC-SRM) approach that we demonstrate is capable of quantitating the individual SA linkage isomers. The LC method is capable of separating sialylated N-glycan isomers differing in α2-3 and α2-6 linkages using a novel superficially porous particle (Fused-Core) Penta-HILIC (hydrophilic interaction liquid chromatography) column. SRM detection provides the relative quantitation of each SA linkage isomer, and minimizes interferences from coeluting glycans that are problematic for UV/Fluorescence based quantitation. With our approach, the relative quantitation of each SA linkage isomer is obtained from a straightforward liquid chromatography-mass spectrometry (LC-MS) experiment. PMID:25299151

  5. Chemical Simulations of Prebiotic Molecules: Interstellar Ethanimine Isomers

    NASA Astrophysics Data System (ADS)

    Quan, Donghui; Herbst, Eric; Corby, Joanna F.; Durr, Allison; Hassel, George

    2016-06-01

    The E- and Z-isomers of ethanimine (CH3CHNH) were recently detected toward the star-forming region Sagittarius (Sgr) B2(N) using the Green Bank Telescope PRIMOS cm-wave spectral data, and imaged by the Australia Telescope Compact Array. Ethanimine is not reported in the hot cores of Sgr B2, but only in gas that absorbs at +64 and +82 km s‑1 in the foreground of continuum emission generated by H ii regions. The ethanimine isomers can serve as precursors of the amino acid alanine and may play important roles in forming biological molecules in the interstellar medium. Here we present a study of the chemistry of ethanimine using a gas-grain simulation based on rate equations, with both isothermal and warm-up conditions. In addition, the density, kinetic temperature, and cosmic ray ionization rate have been varied. For a variety of physical conditions in the warm-up models for Sgr B2(N) and environs, the simulations show reasonable agreement with observationally obtained abundances. Isothermal models of translucent clouds along the same line of sight yield much lower abundances, so that ethanimine would be much more difficult to detect in these sources despite the fact that other complex molecules have been detected there.

  6. Polymerization of the cis- and trans-isomers of bis(triethoxysilyl)-2-butene and comparison of their structural properties

    SciTech Connect

    Shaltout, R.M.; Loy, D.A.; Carpenter, J.P.; Dorhout, K.; Shea, K.J.

    1998-09-01

    The cis and trans isomers of bis-(triethoxysilyl)-2-butene were polymerized by the sol-gel method under various conditions. The trans isomer formed gels under all conditions. The cis isomer formed gels only under basic conditions. Under acidic conditions it formed soluble resins of molecular weight ranging from 88,000 to 180,000 Daltons. Solid state and solution {sup 29}Si NMR revealed that the trans isomer formed condensed gels, and that the resins formed by the cis isomer contained cyclic monomers and/or ordered oligomers.

  7. An α-acetoxy-tirucallic acid isomer inhibits Akt/mTOR signaling and induces oxidative stress in prostate cancer cells.

    PubMed

    El Gaafary, Menna; Büchele, Berthold; Syrovets, Tatiana; Agnolet, Sara; Schneider, Bernd; Schmidt, Christoph Q; Simmet, Thomas

    2015-01-01

    Here we provide evidence that αATA(8,24) (3α-acetyloxy-tir-8,24-dien-21-oic acid) inhibits Akt/mammalian target of rapamycin (mTOR) signaling. αATA(8,24) and other tirucallic acids were isolated from the acetylated extract of the oleo gum resin of Boswellia serrata to chemical homogeneity. Compared with related tirucallic acids, αATA(8,24) was the most potent inhibitor of the proliferation of androgen-insensitive prostate cancer cells in vitro and in vivo, in prostate cancer xenografted onto chick chorioallantoic membranes. αATA(8,24) induced loss of cell membrane asymmetry, caspase-3 activation, and DNA fragmentation in vitro and in vivo. These effects were selective for cancer cells, because αATA(8,24) exerted no overt toxic effects on peripheral blood mononuclear cells or the chick embryo. At the molecular level, αATA(8,24) inhibited the Akt1 kinase activity. Prior to all biochemical signs of cellular dysfunction, αATA(8,24) induced inhibition of the Akt downstream target mTOR as indicated by dephosphorylation of S6K1. This event was followed by decreased expression of cell cycle regulators, such as cyclin D1, cyclin E, and cyclin B1, as well as cyclin-dependent kinases CDK4 and CDK2 and phosphoretinoblastoma protein, which led to inhibition of the cell-cycle progression. In agreement with the mTOR inhibition, αATA(8,24) and rapamycin increased the volume of acidic vesicular organelles. In contrast to rapamycin, αATA(8,24) destabilized lysosomal and mitochondrial membranes and induced reactive oxygen species production in cancer cells. The ability of αATA(8,24) to inhibit Akt/mTOR signaling and to induce simultaneously oxidative stress could be exploited for the development of novel antitumor therapeutics with a lower profile of toxic side effects. PMID:25316122

  8. LC/MS/MS determination and pharmacokinetic study of iridoid glycosides monotropein and deacetylasperulosidic acid isomers in rat plasma after oral administration of Morinda officinalis extract.

    PubMed

    Li, Chunmin; Dong, Jian; Tian, Jingchang; Deng, Zhipeng; Song, Xiujing

    2016-02-01

    Morinda officinalis is a famous traditional Chinese medicine containing iridoid glycoside compounds, such as monotropein and deacetylasperulosidic acid. The aim of the study was to develop a novel and sensitive liquid chromatography-tandem mass spectrometry (LC/MS/MS) method for the simultaneous determination of the two isomeric iridoid glycosides and then evaluate their pharmacokinetic properties in rats. Selected-reaction monitoring mode was employed for quantification of two analytes in rat plasma. The calibration curves were linear over their respective concentration range with correlation coefficient >0.995 for both analytes. Precision for monotropein and deacetylasperulosidic acid ranged from 2.5 to 11.9% relative standard deviation, and the accuracy of two analytes was -2.0-3.7 and -6.4-10.7% relative error, respectively. This method was successfully applied in pharmacokinetic study after oral administration of M. officinalis extract in rats. The results provided a basis for further research on the bioactivity of M. officinalis. PMID:26053360

  9. Past and Present Insights on Alpha-linolenic Acid and the Omega-3 Fatty Acid Family.

    PubMed

    Stark, Aliza H; Reifen, Ram; Crawford, Michael A

    2016-10-25

    Alpha-linolenic acid (ALA) is the parent essential fatty acid of the omega-3 family. This family includes docosahexaenoic acid (DHA), which has been conserved in neural signaling systems in the cephalopods, fish, amphibian, reptiles, birds, mammals, primates, and humans. This extreme conservation, in spite of wide genomic changes of over 500 million years, testifies to the uniqueness of this molecule in the brain and affirms the importance of omega-3 fatty acids. While DHA and its close precursor, eicosapentaenoic acids (EPA), have received much attention by the research community, ALA, as the precursor of both, has been considered of little interest. There are many papers on ALA requirements in experimental animals. Unlike humans, rats and mice can readily convert ALA to EPA and DHA, so it is unclear whether the effect is solely due to the conversion products or to ALA itself. The intrinsic role of ALA has yet to be defined. This paper will discuss both recent and historical findings related to this distinctive group of fatty acids, and will highlight the physiological significance of the omega-3 family. PMID:25774650

  10. Characterization of diacylglycerol isomers in edible oils using gas chromatography-ion trap electron ionization mass spectrometry.

    PubMed

    Zhu, Hanjiang; Clegg, Michael S; Shoemaker, Charles F; Wang, Selina C

    2013-08-23

    Verifying the authenticity of edible oils is of international concern. A new quality control standard for olive oil has been proposed that relates the ratio of 1,2-diacylglycerol (DAG) to 1,3-DAG to sensory aspects of olive oil. DAGs and their isomers are difficult to quantitate and characterize by Flame Ionization Gas Chromatography (GC-FID) due to the lack of suitable standards. Mass detectors offer the advantage of providing structural detail to the eluding DAG(s), thus removing ambiguity to the identification of both resolved and unresolved DAGs in GC chromatograms. In this study, a GC Electron Ionization Mass Spectrometry (GC-EI-MS) method was developed to determine the fatty acid composition and molecular structure of trimethylsilyl (TMS) derivatized DAGs present in edible oils. Twenty-two species of DAG isomers were identified in refined coconut oil and unrefined olive oil utilizing signature fragment ions, [M-15](+), [M-89](+), [M-RCO2](+), [RCO2+58](+) and [M-RCO2CH2](+). The [M-RCO2CH2](+) ion is considered the key diagnostic ion to distinguish between DAG positional isomers. MS/MS spectra of [M-RCO2](+) and [M-15](+) ions obtained from commercial standards containing both 1,2- and 1,3-DAG isomers were used as a model system to confirm the identification of DAG isomers in natural products. Furthermore, a number of reaction mechanisms are proposed to explain the formation of the most abundant mass fragments of DAGs and their isomers. PMID:23880469

  11. Retinoic acid isomers up-regulate ATP binding cassette A1 and G1 and cholesterol efflux in rat astrocytes: implications for their therapeutic and teratogenic effects.

    PubMed

    Chen, Jing; Costa, Lucio G; Guizzetti, Marina

    2011-09-01

    Recent studies suggest that retinoids may be effective in the treatment of Alzheimer's disease, although exposure to an excess of retinoids during gestation causes teratogenesis. Cholesterol is essential for brain development, but high levels of cholesterol have been associated with Alzheimer's disease. We hypothesized that retinoic acid may affect cholesterol homeostasis in rat astrocytes, which regulate cholesterol distribution in the brain, through the up-regulation of cholesterol transporters ATP binding cassette (Abc)a1 and Abcg1. Tretinoin, 13-cis retinoic acid (13-cis-RA), 9-cis-RA, and the selective retinoid X receptor (RXR) agonist methoprene significantly increased cholesterol efflux induced by cholesterol acceptors and protein levels of Abca1 by 2.3- (± 0.25), 3.6- (± 0.42), 4.1- (± 0.5), and 1.75- (± 0.43) fold, respectively, and Abcg1 by 2.1- (± 0.26), 2.2- (± 0.33), 2.5- (± 0.23), and 2.2- (± 0.21) fold, respectively. 13-cis-RA and 9-cis-RA also significantly increased mRNA levels of Abca1 (maximal induction 7.3 ± 0.42 and 2.7 ± 0.17, respectively) and Abcg1 (maximal induction 2.0 ± 0.18 and 1.8 ± 0.09, respectively), and the levels of membrane-bound Abca1 (2.5 ± 0.3 and 2.5 ± 0.40-fold increase, respectively), whereas they significantly decreased intracellular cholesterol content without affecting cholesterol synthesis. The effect of 9-cis-RA on cholesterol homeostasis in astrocytes can be ascribed to the activation of RXR, whereas the effects of 13-cis-RA and tretinoin were independent of either RXRs or retinoic acid receptors. These findings suggest that retinoids affect cholesterol homeostasis in astrocytes and that this effect may be involved in both their therapeutic and teratogenic actions. PMID:21628419

  12. Suzuki-Miyaura coupling of halophenols and phenol boronic acids: systematic investigation of positional isomer effects and conclusions for the synthesis of phytoalexins from pyrinae.

    PubMed

    Schmidt, Bernd; Riemer, Martin

    2014-05-01

    The Suzuki-Miyaura couplings of o-, m-, and p-halophenols with o-, m-, and p-phenol boronic acids were investigated for all combinations under standardized conditions, using Pd/C as a heterogeneous catalyst and water as a solvent. In the case of iodophenols, conventional heating was used, while for bromophenols significantly better results could be obtained using microwave irradiation. This systematic study revealed that 2,4'-biphenol is particularly difficult to access, irrespective of the starting materials used, but that these difficulties can be overcome by using different additives. The conclusions drawn from this investigation allowed us to identify conditions for the protecting group-free or minimized total synthesis of biaryl-type phytoalexins. These compounds possess antibacterial activity and are produced by fruit trees as a response to microbial infection. PMID:24724893

  13. HPLC study of the impurities present in different ursodeoxycholic acid preparations: comparative evaluation of four detectors.

    PubMed

    Roda, A; Gatti, R; Cavrini, V; Cerrè, C; Simoni, P

    1993-08-01

    The use of HPLC with different detectors has been investigated for the analysis of bile acid impurities present in four different commercially available ursodeoxycholic acid preparations. The bile acids were efficiently separated by C18 reversed-phase HPLC using methanol-water (3:2, v/v) as the mobile phase. The detectors used for bile acid detection were: UV at 200 nm refractive index (RI) and an evaporative light scattering mass detector (ELSD II). A prederivatization method with the formation of a fluorescent naphthacyl ester has also been used. GC-MS analysis of Me-TMS bile acid derivatives was included as a reference method. The four ursodeoxycholic acid samples were 98-99% pure. The main impurities present in the samples were chenodeoxycholic acid and to a lesser extent lithocholic acid. Only one sample was found to be almost 100% pure using all the detectors. Significant agreement of the data was found between RI, ELSD II detectors and the fluorescent method; the UV detector was unsuitable for use in this method. The analytical performances of the four detectors for bile acid analysis are reported and discussed. When the four-detector data were compared with the GC-MS method, reasonable agreement resulted. Discordant results were found in the quantitation of trace impurities like lithocholic acid and/or other minor bile acids present in amounts less than 0.1%. PMID:8257741

  14. Process for recovering 4,4 prime dihydroxydiphenyl sulfone from an isomer mixture

    SciTech Connect

    Zemlanicky, F.; Cooker, B.

    1991-03-19

    This patent describes a process for the recovery of 4,4{prime}-bisphenol sulfone from an isomer mixture comprising 4,4{prime}-bisphenol sulfone and 2,4{prime}-bisphenol sulfone. It comprises dissolving the isomer mixture in a basic aqueous solution comprising about one mole of base per mole of the mixture of 4,4{prime}-bisphenol sulfone and 2,4{prime}-bisphenol sulfone to form a basic isomer solution and adding acid to the isomer solution in an amount of from about 0.85 to 0.95 mole per mole of the 4,4{prime}-bisphenol sulfone wherein the acid is added in an amount sufficient to cause selective precipitation of crystals of 4,4{prime}-bisphenol sulfone yet in an amount less than sufficient to neutralize the isomer solution and removing the crystals of 4,4{prime}-bisphenol from the aqueous solution.

  15. Nuclear isomers: stepping stones to the unknown

    SciTech Connect

    Walker, P. M.

    2006-03-13

    The utility of isomers for exploring the nuclear landscape is discussed, including their role in superheavy-element research, and the possibility of observing neutron radioactivity. Emphasis is given to K isomers in deformed nuclei. Transition rates are examined in the NpNn scheme for 2- and 3-quasiparticle K-isomer decays, and in connection with level densities for higher quasiparticle numbers.

  16. Evidence for two interconverting protein isomers in the methotrexate complex of dihydrofolate reductase from Escherichia coli

    SciTech Connect

    Falzone, C.J.; Benkovic, S.J. ); Wright, P.E. )

    1991-02-26

    Two-dimensional {sup 1}H NMR methods and a knowledge of the X-ray crystal structure have been used to make resonance assignments for the amino acid side chains of dihydrofolate reductase from Escherichia coli complexed with methotrexate. The H7 proton on the pteridine ring of methotrexate was found to have NOEs to the methyl protons of Leu-28 which were assigned by using the L28F mutant. These NOEs indicated that the orientation of the methotrexate pteridine ring is similar in both solution and crystal structures. During the initial assignment process, it became evident that many of the resonances in this complex, unlike those of the folate complex, are severally broadened or doubled. The observation of two distinct sets of resonances in a ratio of approximately 2:1 was attributed to the presence of two protein isomers. Many of the side chains with clearly doubled resonances were located in the {beta}-sheet and the active site. Preliminary studies on the apoprotein also revealed doubled resonances in the absence of the inhibitor, indicating the existence of the protein isomers prior to methotrexate binding. In contrast to the methotrexate complex, the binary complex with folate and the ternary MTX-NADPH-DHFR complex presented a single enzyme form. These results are proposed to reflect the ability of folate and NADPH to bind predominantly to one protein isomer.

  17. Preferential hydrophobic interactions are responsible for a preference of D-amino acids in the aminoacylation of 5'-AMP with hydrophobic amino acids

    NASA Technical Reports Server (NTRS)

    Lacey, J. C. Jr; Wickramasinghe, N. S.; Sabatini, R. S.

    1992-01-01

    We have studied the chemistry of aminoacyl AMP to model reactions at the 3' terminus of aminoacyl tRNA for the purpose of understanding the origin of protein synthesis. The present studies relate to the D, L preference in the esterification of 5'-AMP. All N-acetyl amino acids we studied showed faster reaction of the D-isomer, with a generally decreasing preference for D-isomer as the hydrophobicity of the amino acid decreased. The beta-branched amino acids, Ile and Val, showed an extreme preference for D-isomer. Ac-Leu, the gamma-branched amino acid, showed a slightly low D/L ratio relative to its hydrophobicity. The molecular basis for these preferences for D-isomer is understandable in the light of our previous studies and seems to be due to preferential hydrophobic interaction of the D-isomer with adenine. The preference for hydrophobic D-amino acids can be decreased by addition of an organic solvent to the reaction medium. Conversely, peptidylation with Ac-PhePhe shows a preference for the LL isomer over the DD isomer.

  18. Characterization of the Azirinyl Cation and Its Isomers.

    PubMed

    Kokkila Schumacher, Sara I L; Bera, Partha P; Lee, Timothy J

    2016-03-01

    The azirinyl cation (C2H2N(+)) and its geometrical isomers could be present in the interstellar medium. The C2H2N(+) isomers are, however, difficult to identify in interstellar chemistry because of the lack of high-resolution spectroscopic data from laboratory experiments. Ab initio quantum chemical methods were used to characterize the structures, relative energies, and spectroscopic and physical properties of the low energy isomers of the azirinyl cation. We have employed second-order Møller-Plesset perturbation theory (MP2), second-order Z-averaged perturbation theory (ZAPT2), and coupled cluster theory with singles and doubles with perturbative triples CCSD(T) methods along with large correlation consistent basis sets such as cc-pVTZ, cc-pCVTZ, cc-pVQZ, cc-pCVQZ, and cc-pV5Z. Harmonic vibrational frequencies, dipole moments, rotational constants, and proton affinities for the lowest energy isomers were calculated using the CCSD(T) method. Azirinyl cation, a cyclic isomer, is lowest in energy at all levels of theory employed. Azirinyl cation is followed by the cyanomethyl cation (H2CCN)(+), isocyanomethyl cation (H2CNC)(+), and a quasilinear HCCNH(+) cation, which are 13.8, 17.3, and 21.5 kcal mol(-1) above the cyclic isomer, respectively, at the CCSD(T)/cc-pV5Z level of theory. The lowest three isomers all have C2v symmetry and (1)A1 ground electronic states. The quasilinear HCCNH(+) cation has a Cs symmetry planar structure, and a (3)A″ electronic ground state, unlike what some previous work suggested. PMID:26840658

  19. Differential Effects of a Saturated and a Monounsaturated Fatty Acid on MHC Class I Antigen Presentation

    PubMed Central

    Shaikh, S. R.; Mitchell, D.; Carroll, E.; Li, M.; Schneck, J.; Edidin, M.

    2009-01-01

    Lipid overload, associated with metabolic disorders, occurs when fatty acids accumulate in non-adipose tissues. Cells of these tissues use major histocompatibility complex (MHC) class I molecules to present antigen to T cells in order to eliminate pathogens. As obesity is associated with impaired immune responses, we tested the hypothesis that the early stages of lipid overload with saturated fatty acids (SFA) alters MHC class I antigen presentation. Antigen presenting cells (APC) were treated with either the saturated palmitic acid (PA), abundant in the high fat Western diet, or the monounsaturated oleic acid (OA), a component of the Mediterranean diet. PA-treatment lowered APC lysis by activated cytotoxic T lymphocytes and inhibited APC ability to stimulate naïve T cells. Inhibition of immune responses with PA was due to a significant reduction in MHC class I surface expression, inhibition in the rate of APC–T-cell conjugation, and lowering of plasma membrane F-actin levels. OA-treatment had no effect on antigen presentation and upon exposure with PA, prevented the phenotypic effects of PA. OA-treatment conferred protection against changes in antigen presentation by accumulating fatty acids into triglyceride-rich lipid droplets of APC. Our findings establish for the first time a link between the early stages of lipid overload and antigen presentation and suggest that dietary SFA could impair immunity by affecting MHC I-mediated antigen presentation; this could be prevented, paradoxically, by accumulation of triglycerides rich in monounsaturated fatty acids. PMID:18533931

  20. Differential effects of a saturated and a monounsaturated fatty acid on MHC class I antigen presentation.

    PubMed

    Shaikh, S R; Mitchell, D; Carroll, E; Li, M; Schneck, J; Edidin, M

    2008-07-01

    Lipid overload, associated with metabolic disorders, occurs when fatty acids accumulate in non-adipose tissues. Cells of these tissues use major histocompatibility complex (MHC) class I molecules to present antigen to T cells in order to eliminate pathogens. As obesity is associated with impaired immune responses, we tested the hypothesis that the early stages of lipid overload with saturated fatty acids (SFA) alters MHC class I antigen presentation. Antigen presenting cells (APC) were treated with either the saturated palmitic acid (PA), abundant in the high fat Western diet, or the monounsaturated oleic acid (OA), a component of the Mediterranean diet. PA-treatment lowered APC lysis by activated cytotoxic T lymphocytes and inhibited APC ability to stimulate naïve T cells. Inhibition of immune responses with PA was due to a significant reduction in MHC class I surface expression, inhibition in the rate of APC-T-cell conjugation, and lowering of plasma membrane F-actin levels. OA-treatment had no effect on antigen presentation and upon exposure with PA, prevented the phenotypic effects of PA. OA-treatment conferred protection against changes in antigen presentation by accumulating fatty acids into triglyceride-rich lipid droplets of APC. Our findings establish for the first time a link between the early stages of lipid overload and antigen presentation and suggest that dietary SFA could impair immunity by affecting MHC I-mediated antigen presentation; this could be prevented, paradoxically, by accumulation of triglycerides rich in monounsaturated fatty acids. PMID:18533931

  1. Plasma F2-isoprostane class VI isomers at 12-18 weeks of pregnancy are associated with later occurrence of preeclampsia.

    PubMed

    Bilodeau, Jean-François; Qin Wei, Shu; Larose, Jessica; Greffard, Karine; Moisan, Vanessa; Audibert, Francois; Fraser, William D; Julien, Pierre

    2015-08-01

    Preeclampsia (PE) has long been associated with early oxidative stress, although the symptoms occur later in pregnancy. We have hypothesized that the oxidative stress in PE, as characterized by the presence of F2-isoprostane (F2-isoP) isomers in late pregnancy, should already be present in plasma at the first regular visit of the obstetrical follow-up. There are 64 possible isomers of F2-isoPs derived from the oxidation of arachidonic acid (AA), but only one of these isomers has been investigated so far in PE, the classical 8-iso-PGF2α. Here, we have investigated two regioisomers of class III (8-iso-15(R)-PGF2α and 8-iso-PGF2α) and a mix of two isomers of class VI ((±)5-iPF2α-VI) in plasma samples collected prospectively at 12-18 weeks from normotensive controls (n = 60) and pregnant mothers who developed PE later in pregnancy (n = 33). The plasma samples were subjected to alkaline hydrolysis followed by liquid-liquid extraction to extract total F2-isoPs for later quantification by HPLC-MS/MS. The F2-isoPs were normalized to either plasma volume or polyunsaturated fatty acid (PUFA) levels measured by GC-FID in plasma phospholipids. Early in pregnancy, only the class VI F2-isoP isomers were found at concentrations significantly higher in women developing PE later in pregnancy (+13%; p = 0.0074). Normalization of F2-isoPs to their substrate, AA, or the omega-3 to omega-6 ratio improved the predictability of PE as determined by receiver operating characteristic (from area under the curve of 0.67 to 0.68 and 0.70 respectively). Interestingly, omega-3 fatty acids were 25% higher in the control group than in the PE group (P = 0.0225). Omega-6 PUFAs correlated with F2-Isop isomers only in cases of PE (r > 0.377; P >0.03, Spearman correlation). In sum, this study indicates that specific isomers of class VI are significant predictors of PE. This work also suggests that F2-isoP isomers are not all generated and eliminated to the same extent and are influenced by the

  2. Plasma F2-isoprostane class VI isomers at 12–18 weeks of pregnancy are associated with later occurrence of preeclampsia

    PubMed Central

    Bilodeau, Jean-François; Wei, Shu Qin; Larose, Jessica; Greffard, Karine; Moisan, Vanessa; Audibert, Francois; Fraser, William D.; Julien, Pierre

    2016-01-01

    Preeclampsia (PE) has long been associated with early oxidative stress whereas the symptoms occur later in pregnancy. We have hypothesized that the oxidative stress in PE, as characterized by the presence of F2-isoprostanes (F2-isoPs) isomers in late pregnancy, should already be present in plasma at the first regular visit of the obstetrical follow-up. There are 64 possible isomers of F2-isoPs derived from the oxidation of arachidonic acid (AA) but only one of these isomers has been investigated so far in PE, the classical 8-iso-PGF2α. Here, we have investigated two regioisomers of class III (8-iso-15(R)-PGF2α and 8-iso-PGF2α) and a mix of two isomers of class VI (±)5-iPF2α-VI in plasma samples collected prospectively at 12–18 weeks from normotensive controls (n=60) and pregnant mothers who developed PE later in pregnancy (n=33). The plasma samples were subjected to alkaline hydrolysis followed by liquid-liquid extraction to extract total F2-isoPs for later quantification by HPLC-MS/MS. The F2-isoPs were normalized to either plasma volume or polyunsaturated fatty acids (PUFAs) levels measured by GC-FID in plasma phospholipids. Early in pregnancy, only the class VI F2-isoPs isomers were found in concentrations significantly higher in women developing PE later in pregnancy (+ 13%; p=0.0074). Normalisation of F2-isoPs to their substrate, AA, or the omega-3 to omega-6 ratio improved the predictability of PE as determined by receiver operating characteristic (from area under the curve of 0.67 to 0.68 and 0.70 respectively). Interestingly, omega-3 fatty acids were 25% higher in the control group than the PE group (P = 0.0225). Total omega-6 PUFAs correlated to F2-Isop isomers only in cases of PE (r > 0.377; P >0.03, Spearman correlation). In sum, this study indicates that specific isomers of class VI are significant predictors of PE. This work also suggests that F2-isoPs isomers are not all generated and eliminated at the same extent and are influence by the PUFA

  3. Identification of the isomers using principal component analysis (PCA) method

    NASA Astrophysics Data System (ADS)

    Kepceoǧlu, Abdullah; Gündoǧdu, Yasemin; Ledingham, Kenneth William David; Kilic, Hamdi Sukur

    2016-03-01

    In this work, we have carried out a detailed statistical analysis for experimental data of mass spectra from xylene isomers. Principle Component Analysis (PCA) was used to identify the isomers which cannot be distinguished using conventional statistical methods for interpretation of their mass spectra. Experiments have been carried out using a linear TOF-MS coupled to a femtosecond laser system as an energy source for the ionisation processes. We have performed experiments and collected data which has been analysed and interpreted using PCA as a multivariate analysis of these spectra. This demonstrates the strength of the method to get an insight for distinguishing the isomers which cannot be identified using conventional mass analysis obtained through dissociative ionisation processes on these molecules. The PCA results dependending on the laser pulse energy and the background pressure in the spectrometers have been presented in this work.

  4. Metastable isomers - A new class of interstellar molecules

    NASA Technical Reports Server (NTRS)

    Green, S.; Herbst, E.

    1979-01-01

    The abundances of a variety of metastable isomers of small organic molecules, analogous to HNC/HCN, in dense interstellar clouds are considered. These metastable species, some of which are thought to exist as intermediates in laboratory organic chemical reactions, are of considerable interest to chemists. Current ideas of gas-phase, ion-molecule chemistry are utilized to demonstrate that such metastable species should often be present in dense clouds in sufficient abundance to be observed. Unfortunately, the spectral constants of metastable isomers have rarely been determined in the laboratory, and quantum chemical calculations of a varying degree of accuracy must be utilized; results are included of some new quantum chemical calculations. The interstellar chemistry and expected microwave spectra of a representative sample of possibly important interstellar metastable isomers are discussed.

  5. PBPK modeling of the cis- and trans-permethrin isomers and their major urinary metabolites in rats.

    PubMed

    Willemin, Marie-Emilie; Desmots, Sophie; Le Grand, Rozenn; Lestremau, François; Zeman, Florence A; Leclerc, Eric; Moesch, Christian; Brochot, Céline

    2016-03-01

    Permethrin, a pyrethroid insecticide, is suspected to induce neuronal and hormonal disturbances in humans. The widespread exposure of the populations has been confirmed by the detection of the urinary metabolites of permethrin in biomonitoring studies. Permethrin is a chiral molecule presenting two forms, the cis and the trans isomers. Because in vitro studies indicated a metabolic interaction between the trans and cis isomers of permethrin, we adapted and calibrated a PBPK model for trans- and cis-permethrin separately in rats. The model also describes the toxicokinetics of three urinary metabolites, cis- and trans-3-(2,2 dichlorovinyl)-2,2-dimethyl-(1-cyclopropane) carboxylic acid (cis- and trans-DCCA), 3-phenoxybenzoic acid (3-PBA) and 4'OH-phenoxybenzoic acid (4'-OH-PBA). In vivo experiments performed in Sprague-Dawley rats were used to calibrate the PBPK model in a Bayesian framework. The model captured well the toxicokinetics of permethrin isomers and their metabolites including the rapid absorption, the accumulation in fat, the extensive metabolism of the parent compounds, and the rapid elimination of metabolites in urine. Average hepatic clearances in rats were estimated to be 2.4 and 5.7 L/h/kg for cis- and trans-permethrin, respectively. High concentrations of the metabolite 4'-OH-PBA were measured in urine compared to cis- and trans-DCCA and 3-PBA. The confidence in the extended PBPK model was then confirmed by good predictions of published experimental data obtained using the isomers mixture. The extended PBPK model could be extrapolated to humans to predict the internal dose of exposure to permethrin from biomonitoring data in urine. PMID:26802525

  6. Isomer Triggering via Nuclear Excitation by Electron Capture

    SciTech Connect

    Palffy, Adriana; Evers, Joerg; Keitel, Christoph H.

    2007-10-26

    Triggering of long-lived nuclear isomeric states via coupling to the atomic shells in the process of nuclear excitation by electron capture (NEEC) is studied. NEEC occurring in highly charged ions can excite the isomeric state to a triggering level that subsequently decays to the ground state. We present total cross sections for NEEC isomer triggering considering experimentally confirmed low-lying triggering levels and reaction rates based on realistic experimental parameters in ion storage rings. A comparison with other isomer triggering mechanisms shows that, among these, NEEC is the most efficient.

  7. New high spin isomers obtained in thermal fission

    SciTech Connect

    Fogelberg, B.; Mach, H.; Gausemel, H.; Omtvedt, J. P.; Mezilev, K. A.

    1998-10-26

    The product nuclei following fission often are initially highly excited and have high angular momenta. As a consequence, there is a substantial probability for the population of isomeric yrast traps in the vicinity of closed shells. The excitation energies and decay properties of such isomers give important formation regarding the shell structure and interaction energies. Recent experiments at the OSIRIS mass separator have revealed a number of isomers in the {sup 132}Sn region having angular momenta exceeding 10 units. A brief presentation is given of some experimental results and their interpretation.

  8. Isomer-Specific Distribution of Perfluoroalkyl Substances in Blood.

    PubMed

    Jin, Hangbiao; Zhang, Yifeng; Jiang, Weiwei; Zhu, Lingyan; Martin, Jonathan W

    2016-07-19

    Perfluoroalkyl substances (PFASs) such as perfluorohexanesulfonate (PFHxS), perfluorooctanoate (PFOA), perfluorooctanesulfonate (PFOS) and PFOS-precursors are routinely measured in human plasma and serum, but their relative abundance in the blood cell fraction has not been carefully examined, particularly at the isomer-specific level. Human plasma and whole blood were collected and partitioning behaviors of PFASs and their isomers between plasma and blood cells were investigated. In human samples, mass fraction in plasma (Fp) for PFASs increased among perfluoroalkyl carboxylates as the carbon chain length increased from C6 (mean 0.24) to C11 (0.87), indicating preference for the plasma fraction with increasing chain length. However, among perfluoroalkyl sulfonates, PFHxS (mean 0.87) had a slightly higher Fp than PFOS (0.85). In vitro assays with spiked Sprague-Dawley rat blood were also conducted, and the results showed that PFOS-precursors had lower Fp values than perfluoroalkyl acids, with perfluoroctanesulfonamide having the lowest Fp (mean 0.24). Consistently, linear isomers of PFOS and PFOS-precursors had lower mean Fp than their corresponding total branched isomers. Multiplying by a factor of 2 is not a reasonable method to convert from whole blood to plasma PFAS concentrations, and current ratios could be used as more accurate conversion factors. PMID:27295125

  9. Synthesis of a volatile compound of the (2 minus ) Ho-160 nuclear isomer

    SciTech Connect

    Hartmann, F.X.; Naumann, R.A. )

    1988-10-01

    The synthesis of volatile compounds of radioactive holmium atoms are described and the gamma-ray spectra following the decay of the longest-lived isomer (Ho-160) presented. This latter isomer has an ultra-low energy transition of potential interest in laser driven nuclear inter-level transfer studies.

  10. Interconversion of diborane(4) isomers

    NASA Technical Reports Server (NTRS)

    Stanton, John F.; Gauss, Juergen; Bartlett, Rodney J.; Helgaker, Trygve; Jorgensen, Poul; Jensen, Hans J. A.; Taylor, Peter R.

    1992-01-01

    Highly correlated electronic structure computations using many-body perturbation theory and coupled-cluster gradient techniques are used to study the reaction pathway that links the two forms (C2u and D2d) of diborane(4). The results obtained indicate that a low-energy pathway exists for interconversion of the two low-lying isomers of diborane(4). The proposed mechanism consists of a single concerted but nonsynchronous rotation of the BH2 groups. The pathway first follows an idealized reaction coordinate which preserves C2 symmetry, but then bifurcates at a branch point, leading to two equivalent transition states which lack nontrivial elements of symmetry.

  11. Spectroscopic and computational study of a new isomer of salinomycin

    NASA Astrophysics Data System (ADS)

    Pankiewicz, Radosław

    2013-09-01

    A new derivative of polyether ionophore salinomycin was obtained as a result of a rearrangement catalysed by sulphuric acid in two-phase medium of water/methylene chloride solution. The new isomer was fully characterized by multinuclear 2D NMR, NOESY and MALDI-TOF. The properties of the new compound were additionally study by semiempirical (PM5) and DFT (B3LYP) methods. A potential mechanism of the rearrangement was also proposed.

  12. Anomalous Reactivity and Selectivity in the Intermolecular Diels-Alder Reactions of Multisubstituted Acyclic Dienes with Geometrical Isomers of Enals.

    PubMed

    Zhou, Jia-Hui; Cai, Sai-Hu; Xu, Yun-He; Loh, Teck-Peng

    2016-05-20

    A Lewis-acid catalyzed intermolecular Diels-Alder reaction between multisubstituted acyclic dienes and the E and Z isomers of α,β-enals was studied. It was found that the diene reacted selectively with the Z-isomer of the α,β-enal. PMID:27132468

  13. Ozonation kinetics of phenolic acids present in wastewaters from olive oil mills

    SciTech Connect

    Benitez, F.J.; Beltran-Heredia, J.; Acero, J.L.; Pinilla, M.L.

    1997-03-01

    A kinetic study of the degradation by ozone of eight phenolic acids present in wastewaters from olive oil mills has been performed by using a competition kinetic method. The selected phenolic acids are: caffeic, p-coumaric, syringic, vanillic, 3,4,5-trimethoxybenzoic, veratric, p-hydroxy-benzoic, and protocatechuic. The influence of the operating variables (temperature, pH, and ozone partial pressure in the gas stream) is established, and the stoichiometric ratios for the individual direct reactions between ozone and each acid are determined. Once the reaction rate constants are evaluated, they are correlated as a function of temperature and pH into kinetic expressions which are provided for every phenolic acid. The global process occurs in the fast and pseudo-first-order kinetic regime of absorption, a condition required by the competition model to be used.

  14. Complete Hexose Isomer Identification with Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Nagy, Gabe; Pohl, Nicola L. B.

    2015-04-01

    The first analytical method is presented for the identification and absolute configuration determination of all 24 aldohexose and 2-ketohexose isomers, including the D and L enantiomers for allose, altrose, galactose, glucose, gulose, idose, mannose, talose, fructose, psicose, sorbose, and tagatose. Two unique fixed ligand kinetic method combinations were discovered to create significant enough energetic differences to achieve chiral discrimination among all 24 hexoses. Each of these 24 hexoses yields unique ratios of a specific pair of fragment ions that allows for simultaneous determination of identification and absolute configuration. This mass spectrometric-based methodology can be readily employed for accurate identification of any isolated monosaccharide from an unknown biological source. This work provides a key step towards the goal of complete de novo carbohydrate analysis.

  15. Reversed Phase High-Performance Liquid Chromatographic Ultra-violet (Photo Diode Array) Quantification of Oleanolic Acid and its Isomer Ursolic Acid for Phytochemical Comparison and Pharmacological Evaluation of Four Leucas Species Used in Ayurveda

    PubMed Central

    Shukla, Pushpendra Kumar; Misra, Ankita; Srivastava, Sharad; Rawat, Ajay K. S.

    2016-01-01

    Content: Different Leucas species are well known as “Dronpushpi,” a well-known herb of Ayurveda, used in the treatment of various ailments. Objective: Evaluation of four industrially important Leucas species for their in vitro antidiabetic potential and radical scavenging effect along with high-performance liquid chromatographic quantification of the bioactive triterpenes. Materials and Methods: The quantification of triterpenes was carried out on C-18 column with acetonitrile and water (90:10) as the solvent system at a detection wavelength of 210 nm. In vitro antidiabetic activity was evaluated by α-amylase inhibition assay based on starch–iodine and 3,5 dinitrosalicylic acid (DNS) method. Antioxidant activity was calculated by five different models, namely total phenolic and total flavonoid content, free radical scavenging activity by 1-1-diphenyl-2-pic-rylhydrazyl (DPPH), ferric-reducing power assay, and the total antioxidant capacity. Results: Maximum concentration of oleanolic acid was found in Leucas cristata, followed by Leucas mollissima, Leucas Aspera, and Leucas biflora. Ursolic acid was highest in L. mollissima and then in L. biflora, L. cristata, and L. aspera, respectively. In in vitro antidiabetic activity, IC50 of L. aspera (1.56 ± 0.01 mg/ml) and L. mollissima (0.75 ± 0.005 mg/ml) were found to be highest in DNS and iodine starch assay. IC50 in DPPH assay ranges from 0.6 ± 0.011 to 1.68 ± 0.011 mg/ml. Antioxidant capacity follows the order; L. aspera > L. mollissima > L. biflora > L. cristata. Conclusion: Promising activities were observed in targeted species, thus L. mollissima, L. biflora, and L. cristata can be used alternatively as a substitute to L. aspera. SUMMARY Physicochemical parameters are within the limit as per the Ayurvedic Pharmacopoeia of IndiaMaximum concentration of oleanolic acid was found in Leucas cristata; however, ursolic acid was highest in Leucas mollissimaIn vitro antidiabetic activity of Leucas aspera and L

  16. Comparative pharmacological activity of optical isomers of phenibut.

    PubMed

    Dambrova, Maija; Zvejniece, Liga; Liepinsh, Edgars; Cirule, Helena; Zharkova, Olga; Veinberg, Grigory; Kalvinsh, Ivars

    2008-03-31

    Phenibut (3-phenyl-4-aminobutyric acid) is a GABA (gamma-aminobutyric acid)-mimetic psychotropic drug which is clinically used in its racemic form. The aim of the present study was to compare the effects of racemic phenibut and its optical isomers in pharmacological tests and GABAB receptor binding studies. In pharmacological tests of locomotor activity, antidepressant and pain effects, S-phenibut was inactive in doses up to 500 mg/kg. In contrast, R-phenibut turned out to be two times more potent than racemic phenibut in most of the tests. In the forced swimming test, at a dose of 100 mg/kg only R-phenibut significantly decreased immobility time. Both R-phenibut and racemic phenibut showed analgesic activity in the tail-flick test with R-phenibut being slightly more active. An GABAB receptor-selective antagonist (3-aminopropyl)(diethoxymethyl)phosphinic acid (CGP35348) inhibited the antidepressant and antinociceptive effects of R-phenibut, as well as locomotor depressing activity of R-phenibut in open field test in vivo. The radioligand binding experiments using a selective GABAB receptor antagonist [3H]CGP54626 revealed that affinity constants for racemic phenibut, R-phenibut and reference GABA-mimetic baclofen were 177+/-2, 92+/-3, 6.0+/-1 microM, respectively. We conclude that the pharmacological activity of racemic phenibut relies on R-phenibut and this correlates to the binding affinity of enantiomers of phenibut to the GABAB receptor. PMID:18275958

  17. The optical nature of methylsuccinic acid in human urine

    NASA Technical Reports Server (NTRS)

    Zeitman, B.; Lawless, J. G.

    1975-01-01

    Methylsuccinic acid was isolated from human urine, derivatized as the di-S-(+)-2-butyl ester, and analyzed using a gas chromatographic system capable of separating the enantiomers of the derivative. The R-(+)-isomer was found to be present. Methylsuccinic acid is potentially important as a criterion for abiogenicity, having been obtained as a racemic mixture from sources known to be abiotic.

  18. How are the Concepts and Theories of Acid-Base Reactions Presented? Chemistry in Textbooks and as Presented by Teachers

    ERIC Educational Resources Information Center

    Furio-Mas, Carlos; Calatayud, Maria Luisa; Guisasola, Jenaro; Furio-Gomez, Cristina

    2005-01-01

    This paper investigates the views of science and scientific activity that can be found in chemistry textbooks and heard from teachers when acid-base reactions are introduced to grade 12 and university chemistry students. First, the main macroscopic and microscopic conceptual models are developed. Second, we attempt to show how the existence of…

  19. Utilization of Lactate Isomers by Propionibacterium freudenreichii subsp. shermanii: Regulatory Role for Intracellular Pyruvate

    PubMed Central

    Crow, Vaughan L.

    1986-01-01

    Five strains of Propionibacterium freudenreichii subsp. shermanii utilized the l-(+) isomer of lactate at a faster rate than they did the d-(−) isomer when grown with a mixture of lactate isomers under a variety of conditions. ATCC 9614, grown anaerobically in defined medium containing 160 mM dl-lactate, utilized only 4 and 15% of the d-(−)-lactate by the time 50 and 90%, respectively, of the l-(+)-lactate was used. The intracellular pyruvate concentration was high (>100 mM) in the initial stages of lactate utilization, when either dl-lactate or the l-(+) isomer was the starting substrate. The concentration of this intermediate dropped during dl-lactate fermentation such that when only d-(−)-lactate remained, the concentration was <20 mM. When only the d-(−) isomer was initially present, a similar relatively low concentration of intracellular pyruvate was present, even at the start of lactate utilization. The NAD+-independent lactate dehydrogenase activities in extracts showed different kinetic properties with regard to pyruvate inhibition, depending upon the lactate isomer present. Pyruvate gave a competitive inhibitor pattern with l-(+)-lactate and a mixed-type inhibitor pattern with d-(−)-lactate. It is suggested that these properties of the lactate dehydrogenases and the intracellular pyruvate concentrations explain the preferential use of the l-(+) isomer. PMID:16347134

  20. Kinetics of Non-Catalytic Esterification of Free Fatty Acids Present in Jatropha Oil.

    PubMed

    Prasanna Rani, Karna Narayana; Ramana Neeharika, Tulasi Sri Venkata; Kumar, Thella Prathap; Satyavathi, Bankupalli; Sailu, Chintha

    2016-05-01

    Non-catalytic esterfication of free fatty acids (FFA) present in vegetable oils is an alternative pretreatment process for the biodiesel production. Biodiesel, consists of long-chain fatty acid methyl esters (FAME) and is obtained from renewable sources such as vegetable oils or animal fat. This study presents kinetics of thermal esterification of free fatty acids present in jatropha oil with methanol. The effect of process parameters like reaction time (1-5 h), temperature (170-190°C) and oil to methanol ratio (1:3-1:5) at constant pressure was investigated. The optimal conditions were found to be oil to methanol ratio of 1:4, 190°C, at 27.1 bar and 5 h which gave a maximum conversion of 95.1%. A second order kinetic model for both forward and backward reactions was proposed to study the reaction system. A good agreement was observed between the experimental data and the model values. The activation energy for forward reaction and the heat of reaction were found to be 36.364 Kcal/mol and 1.74 Kcal/mol respectively. PMID:27086997

  1. Introduction of a single isomer beta agonist.

    PubMed

    Rau, J L

    2000-08-01

    The release of levalbuterol offers the first approved single-isomer beta agonist for oral inhalation. Data from in vitro studies support the concept that S albuterol is not inactive and may have properties antagonistic to bronchodilation. There is some variability in the results of clinical studies with the separate isomers of albuterol, which suggests the need for further study. The introduction of levalbuterol into general clinical use in managing asthma and chronic obstructive disease should begin to offer additional information on the effects of a single isomer beta agonist in comparison to previous racemic mixtures. PMID:10963321

  2. Trans isomers of EPA and DHA in omega-3 products on the European market.

    PubMed

    Sciotto, Caterina; Mjøs, Svein A

    2012-07-01

    The levels of trans isomers of eicosapentaenoic (EPA) acid and docosahexaenoic acid (DHA) in 77 omega-3 products on the European market have been studied. Fatty acids were analyzed as fatty acid methyl esters by gas chromatography with a flame ionization detector, using a cyanopropyl coated stationary phase. The amount of mono-trans EPA isomers relative to the corresponding all-cis isomer ranged from 0.19 to 4.5 %. The corresponding values for mono-trans DHA relative to the all-cis isomer ranged from 0.25 to 5.9 %. There was a strong correlation between the degree of isomerization of EPA and DHA, showing that DHA was 1.26 times more isomerized than EPA. Division of the samples into different product groups showed that samples with a low degree of isomerization were found in all groups, except one. This shows that a high degree of isomerization is avoidable, and also points to deodorization of the oils as the main source of trans isomers. PMID:22566205

  3. Isomer-specific combustion chemistry in allene and propyne flames

    SciTech Connect

    Hansen, Nils; Miller, James A.; Westmoreland, Phillip R.; Kasper, Tina; Kohse-Hoeinghaus, Katharina; Wang, Juan; Cool, Terrill A.

    2009-11-15

    A combined experimental and modeling study is performed to clarify the isomer-specific combustion chemistry in flames fueled by the C{sub 3}H{sub 4} isomers allene and propyne. To this end, mole fraction profiles of several flame species in stoichiometric allene (propyne)/O{sub 2}/Ar flames are analyzed by means of a chemical kinetic model. The premixed flames are stabilized on a flat-flame burner under a reduced pressure of 25 Torr (=33.3 mbar). Quantitative species profiles are determined by flame-sampling molecular-beam mass spectrometry, and the isomer-specific flame compositions are unraveled by employing photoionization with tunable vacuum-ultraviolet synchrotron radiation. The temperature profiles are measured by OH laser-induced fluorescence. Experimental and modeled mole fraction profiles of selected flame species are discussed with respect to the isomer-specific combustion chemistry in both flames. The emphasis is put on main reaction pathways of fuel consumption, of allene and propyne isomerization, and of isomer-specific formation of C{sub 6} aromatic species. The present model includes the latest theoretical rate coefficients for reactions on a C{sub 3}H{sub 5} potential [J.A. Miller, J.P. Senosiain, S.J. Klippenstein, Y. Georgievskii, J. Phys. Chem. A 112 (2008) 9429-9438] and for the propargyl recombination reactions [Y. Georgievskii, S.J. Klippenstein, J.A. Miller, Phys. Chem. Chem. Phys. 9 (2007) 4259-4268]. Larger peak mole fractions of propargyl, allyl, and benzene are observed in the allene flame than in the propyne flame. In these flames virtually all of the benzene is formed by the propargyl recombination reaction. (author)

  4. The sealed lead-acid battery: performance and present aircraft applications

    NASA Astrophysics Data System (ADS)

    Timmons, John; Kurian, Raju; Goodman, Alan; Johnson, William R.

    The United States Navy has flown valve-regulated lead-acid batteries (VRLA) for approximately 22 years. The first VRLA aircraft batteries were of a cylindrical cell design and these evolved to a prismatic design to save weight, volume, and to increase rate capability. This paper discusses the evolution of the VRLA aircraft battery designs, present VRLA battery performance, and battery size availability along with their aircraft applications (both military and commercial). The paper provides some of the reliability data from present applications. Finally, the paper discusses what future evolution of the VRLA technology is required to improve performance and to remain the technology of choice over other sealed aircraft battery designs.

  5. Differential adsorption of CHON isomers at interstellar grain surfaces

    NASA Astrophysics Data System (ADS)

    Lattelais, M.; Pauzat, F.; Ellinger, Y.; Ceccarelli, C.

    2015-06-01

    Context. The CHON generic chemical formula covers different isomers such as isocyanic acid (HNCO), cyanic acid (HOCN), fulminic acid (HCNO), and isofulminic acid (HONC); the first three have been identified in a large variety of environments in the interstellar medium (ISM). Several phenomena could be at the origin of the observed abundances, such as different pathways of formation and destruction involving gas phase reactions with different possible activation barriers and/or surface processes depending on the local temperature and the nature of the support. Aims: The scope of this article is to shed some light on the interaction of the CHON isomers with interstellar grains as a function of the nature of the surface and to determine the corresponding adsorption energies in order to find whether this phenomenon could play a role in the abundances observed in the ISM. Methods: The question was addressed by means of numerical simulations using first principle periodic density functional theory (DFT) to represent the grain support as a solid of infinite dimension. Results: Regardless of the nature of the model surface (water ice, graphene, silica), two different classes of isomers were identified: weakly bound (HNCO and HCNO) and strongly bound (HOCN and HONC), with the adsorption energies of the latter group being about twice those of the former. The range of the adsorption energies is (from highest to lowest) HOCN > HONC > HNCO > HCNO. They are totally disconnected from the relative stabilities, which range from HNCO > HOCN > HCNO > HONC. Conclusions: The possibility of hydrogen bonding is the discriminating factor in the trapping of CHON species on grain surfaces. Whatever the environment, differential adsorption is effective and its contribution to the molecular abundances should not be ignored. The theoretical adsorption energies provided here could be profitably used for a more realistic modeling of molecule-surfaces interactions.

  6. Subthreshold kaons would reveal density isomers

    SciTech Connect

    Hartnack, C.; Aichelin, J.; Stoecker, H.; Greiner, W. Gesellschaft fuer Schwerionenforschung, D-64220 Darmstadt Institut fuer Theoretische Physik, Universitaet Frankfurt, D-60065 Frankfurt )

    1994-06-13

    If density isomers exist they can be detected by measuring the excitation function of subthreshold kaon production. When the system reaches the density where the density isomer has influence on the equation of state (which depends on the beam energy and on the optical potential), we observe a jump in the cross section of the kaons whereas other observables change little. Above threshold [bar [Lambda

  7. Isomer effects on polyimide properties

    NASA Technical Reports Server (NTRS)

    Stump, B. L.

    1974-01-01

    The polymerization of 2,4'-methylene-dianiline with benzophenone tetracarboxylic acid dianhydride yields high molecular weight polyamic acid. Polyimide is formed when films of the polyamic acid are cured between 200 - 300 C. A lower molecular weight polyamic acid is obtained from 2,2'-MDA with BTDA, but it appears that a lowering of the reaction temperature will yield high molecular weight polymer. Evaluation of these polymers is underway. Continued efforts to synthesize 2,3'- MDA and 2,3'-diaminobenzophenone have met with little success.

  8. Search for the isomers of C2H3NO and C2H3NS in the Interstellar Medium

    NASA Astrophysics Data System (ADS)

    Etim, Emmanuel; Chakrabarti, Sandip Kumar; Das, Ankan; Gorai, Prasanta; Arunan, Elangannan

    2016-07-01

    With about 40% of all the known interstellar and circumstellar molecules having their isomeric analogues as known astromolecules, isomerism remains one of the leading themes in interstellar chemistry. In this regard, the recent detection of methyl isocyanate (with a number of isomeric analogues) in the Sgr B2(N) giant molecular cloud opens a new window for the possible astronomical detection of other C_2H_3NO isomers. The present work looks at the possibility of detecting other isomers of methyl isocyanate by considering different factors such as thermodynamic stability of the different isomers with respect to the Energy, Stability and Abundance (ESA) relationship, effect of interstellar hydrogen bonding with respect to the formation these isomers on the surface of the interstellar dust grains, possible formation routes for these isomers, spectroscopic parameters for potential astromolecules among these isomers, chemical modeling among other studies. The same studies are repeated for the C_2H_3NS isomers which are the isoelectroninc analogues of the C_2H_3NO isomers taking into account the unique chemistry of S and O-containing interstellar molecular species. Among the C_2H_3NS isomers, methyl isothiocyanate remains the most potential candidate for astronomical observation.

  9. Structural isomers of C2N(+) - A selected-ion flow tube study

    NASA Technical Reports Server (NTRS)

    Knight, J. S.; Petrie, S. A. H.; Freeman, C. G.; Mcewan, M. J.; Mclean, A. D.

    1988-01-01

    Reactivities of the structural isomers CCN(+) and CNC(+) were examined in a selected-ion flow tube at 300 + or - 5 K. The less reactive CNC(+) isomer was identified as the product of the reactions of C(+) + HCN and C(+) + C2N2; in these reactions only CNC(+) can be produced because of energy constraints. Rate coefficients and branching ratios are reported for the reactions of each isomer with H2, CH4, NH3, H2O, C2H2, HCN, N2, O2, N2O, and CO2. Ab initio calculations are presented for CCN(+) and CNC(+); a saddle point for the reaction CCN(+) yielding CNC(+) is calculated to be 195 kJ/mol above CNC(+). The results provide evidence that the more reactive CCN(+) isomer is unlikely to be present in measurable densities in interstellar clouds.

  10. High-harmonic spectroscopy of molecular isomers

    SciTech Connect

    Wong, M. C. H.; Brichta, J.-P.; Bhardwaj, V. R.; Spanner, M.; Patchkovskii, S.

    2011-11-15

    We demonstrate that high-order-harmonic generation (HHG) spectroscopy can be used to probe stereoisomers of randomly oriented 1,2-dichloroethylene (C{sub 2}H{sub 2}Cl{sub 2}) and 2-butene (C{sub 4}H{sub 8}). The high-harmonic spectra of these isomers are distinguishable over a range of laser intensities and wavelengths. Time-dependent numerical calculations of angle-dependent ionization yields for 1,2-dichloroethylene suggest that the harmonic spectra of molecular isomers reflect differences in their strong-field ionization. The subcycle ionization yields for the cis isomer are an order of magnitude higher than those for the trans isomer. The sensitivity in discrimination of the harmonic spectra of cis- and trans- isomers is greater than 8 and 5 for 1,2-dichloroethylene and 2-butene, respectively. We show that HHG spectroscopy cannot differentiate the harmonic spectra of the two enantiomers of the chiral molecule propylene oxide (C{sub 3}H{sub 6}O).

  11. Comparison of isomers of ketamine on catalepsy in the rat and electrical activity of the brain and behavior in the cat.

    PubMed

    Benthuysen, J L; Hance, A J; Quam, D D; Winters, W D

    1989-10-01

    The present study compared the relative potency and efficacy of the two isomers of ketamine on the duration of catalepsy (loss of righting reflex) in female rats and on the behavior and electroencephalogram of cats. In the rat, at small doses, the S(+) isomer was more potent than the R(-) isomer or racemic ketamine, while at larger doses, the S(+) isomer and the racemate were equipotent and the R(-) isomer was significantly less potent. Tolerance developed rapidly to the effects of either isomer and both were equally cross-tolerant to racemic ketamine. Sub-effective doses of morphine significantly increased the potency of S(+), R(-) and racemic ketamine on the duration of catalepsy. Sub-effective doses of either isomer augmented the duration of catalepsy, induced by small doses of morphine, but reduced that of large doses. In cats, there was a parallel time course and progression of behavioral and electroencephalographic states in response to equal total doses of either racemic ketamine, an artificial 50:50 mixture of S(+) and R(-) isomers, or the S(+) isomer alone; approximately equivalent effects required twice the dose of the R(-) isomer. It is concluded that there is a common site of action for the two isomers, but there is also a stereospecific difference in potency, as regards the induction of catalepsy in the rat and behavioral and electroencephalographic effects in the cat. Stereospecificity was not apparent in the development of tolerance, cross-tolerance or the augmentation of the response to morphine. PMID:2812279

  12. Isomer Energy Differences for the C4H3 and C4H5 Isomers UsingDiffusion Monte Carlo

    SciTech Connect

    Domin, D.; Lester Jr., W.A.; Whitesides, R.; Frenklach, M.

    2007-12-01

    A new diffusion Monte Carlo study is performed on the isomers of C{sub 4}H{sub 3} and C{sub 4}H{sub 5} emulating the methodology of a previous study [Int. J. Chem. Kinetics 33, 808 (2001)]. Using the same trial wave function form of the previous study, substantially different isomerization energies were found owing to the use of larger walker populations in the present work. The energy differences between the E and I isomers of C{sub 4}H{sub 3} were found to be 10.5 {+-} 0.5 kcal/mol and for C{sub 4}H{sub 5}, 9.7 {+-} 0.6 kcal/mol. These results are in reasonable accord with recent MRCI and CCSD(T) findings.

  13. A Novel Method for Presenting the Amino Acids in an Introductory Biochemistry Course.

    ERIC Educational Resources Information Center

    Kuehl, LeRoy

    1978-01-01

    Introduces an approach to teaching amino acids that employs the use of a poem containing information on the structure and properties of amino acids, and of slides illustrating the poem. Student response to the method was positive. (MA)

  14. Removal of persistent organic pollutant hexachlorocyclohexane isomers by advanced oxidation process.

    PubMed

    2012-04-01

    Organochlorine insecticide Lindane (gamma-Hexachlorocyclohexane) and its isomers (alpha, beta, delta-HCH) are recalcitrant and toxic compounds. They were progressively banished in most of the countries, because of their persistence and toxicity. Due to their nonselective production process and widespread use, they are still occurring in the environment. These insecticides and isomers were detected in all media like soil, ground water, sediments, vegetables and even in human tissues. In this study, UV, H2O2, UV+H2O2, Fenton's reagent, UV+Fenton's reagent, Advanced Oxidation Process (AOP) have been applied for degradation of HCH isomers (a, beta, gamma and delta-HCH). The results revealed that the UV+H2O2 treatment was most effective, which could do 99% degradation of all isomers of HCH within 75 minutes. The results in detail are presented and discussed in this paper. PMID:24749381

  15. An isomer-specific high-energy collision-induced dissociation MS/MS database for forensic applications: a proof-of-concept on chemical warfare agent markers.

    PubMed

    Subramaniam, Raja; Östin, Anders; Nygren, Yvonne; Juhlin, Lars; Nilsson, Calle; Åstot, Crister

    2011-09-01

    Spectra database search has become the most popular technique for the identification of unknown chemicals, minimizing the need for authentic reference chemicals. In the present study, an isomer-specific high-energy collision-induced dissociation (CID) MS/MS spectra database of 12 isomeric O-hexyl methylphosphonic acids (degradation markers of nerve agents) was created. Phosphonate anions were produced by the electrospray ionization of phosphonic acids or negative-ion chemical ionization of their fluorinated derivatives and were analysed in a hybrid magnetic-sector-time-of-flight tandem mass spectrometer. A centre-of-mass energy (E(com)) of 65 eV led to an optimal sequential carbon-carbon bond breakage, which was interpreted in terms of charge remote fragmentation. The proposed mechanism is discussed in comparison with the routinely used low-energy CID MS/MS. Even-mass (odd-electron) charge remote fragmentation ion series were diagnostic of the O-alkyl chain structure and can be used to interpret unknown spectra. Together with the odd-mass ion series, they formed highly reproducible, isomer-specific spectra that gave significantly higher database matches and probability factors (by 1.5 times) than did the EI MS spectra of the trimethylsilyl derivatives of the same isomers. In addition, ionization by negative-ion chemical ionization and electrospray ionization resulted in similar spectra, which further highlights the general potential of the high-energy CID MS/MS technique. PMID:21915956

  16. Nuclear isomer suitable for gamma ray laser

    NASA Technical Reports Server (NTRS)

    Jha, S.

    1979-01-01

    The operation of gamma ray lasers (gasers) are studied. It is assumed that the nuclear isomers mentioned in previously published papers have inherent limitations. It is further assumed that the judicious use of Bormann effect or the application of the total external reflection of low energy gamma radiation at grazing angle of incidence may permit the use of a gaser crystal sufficiently long to achieve observable stimulated emission. It is suggested that a long lived 0(+) isomer decaying by low energy gamma ray emission to a short lived 2(+) excited nuclear state would be an attractive gaser candidate. It is also suggested that the nuclear isomer be incorporated in a matrix of refractory material having an electrostatic field gradient whose principal axis lies along the length of the medium. This results in the preferential transmission of electric quadrupole radiation along the length of the medium.

  17. K isomers as probes of nuclear structure

    SciTech Connect

    Tandel, S. K.

    2014-08-14

    K isomers are studied in Pu and Cm isotopes, and also in Hf and W nuclei. Many high-K states, several of which are isomeric, are identified. Lifetime measurements spanning the ns-s range have been performed, and decay paths of isomers established. Rotational bands built on high-K states are also identified in many cases. Isomer decays are considerably hindered in many instances, both in the A≈180 and 250 regions indicating that K is an approximately conserved quantum number. High-K states become the favored excitation mode at high spins in the A≈180 region. The energies of the 2-quasiparticle high-K states in Cm isotopes suggest the presence of a deformed subshell gap at N=152.

  18. An Assessment of Nuclear Isomers as an Energy Storage Medium

    SciTech Connect

    Hartouni, Edward P.

    2009-03-16

    Nuclear Isomers have been suggested as a potential high energy density medium that might be used to store energy. This talk assesses the state of the science supporting key elements of using nuclear isomers in energy storage applications. The focus is on the nuclear isomer {sup 178m2}Hf which has been most widely suggested for energy storage applications. However, the science issues apply to all nuclear isomer. The assessment addresses the production of the nuclear isomer, and inducing the release of the isomer. Also discussed are novel speculations on photon and/or neutron chain reactions, both as a 'pure' material as well as mixed with other materials.

  19. An Assessment of Nuclear Isomers as an Energy Storage Medium

    SciTech Connect

    Hartouni, E P

    2008-12-08

    Nuclear Isomers have been suggested as a potential high energy density medium that might be used to store energy. This talk assesses the state of the science supporting key elements of using nuclear isomers in energy storage applications. The focus is on the nuclear isomer {sup 178m2}Hf which has been most widely suggested for energy storage applications. However, the science issues apply to all nuclear isomer. The assessment addresses the production of the nuclear isomer, and inducing the release of the isomer. Also discussed are novel speculations on photon and/or neutron chain reactions, both as a 'pure' material as well as mixed with other materials.

  20. A conjugated fatty acid present at high levels in bitter melon seed favorably affects lipid metabolism in hepatocytes by increasing NAD(+)/NADH ratio and activating PPARα, AMPK and SIRT1 signaling pathway.

    PubMed

    Chen, Gou-Chun; Su, Hui-Min; Lin, Yu-Shun; Tsou, Po-Yen; Chyuan, Jong-Ho; Chao, Pei-Min

    2016-07-01

    α-Eleostearic acid (α-ESA), or the cis-9, trans-11, trans-13 isomer of conjugated linolenic acid, is a special fatty acid present at high levels in bitter melon seed oil. The aim of this study was to examine the effect of α-ESA on hepatic lipid metabolism. Using H4IIEC3 hepatoma cell line, we showed that α-ESA significantly lowered intracellular triglyceride accumulation compared to α-linolenic acid (LN), used as a fatty acid control, in a dose- and time-dependent manner. The effects of α-ESA on enzyme activities and mRNA profiles in H4IIEC3 cells suggested that enhanced fatty acid oxidation and lowered lipogenesis were involved in α-ESA-mediated triglyceride lowering effects. In addition, α-ESA triggered AMP-activated protein kinase (AMPK) activation without altering sirtuin 1 (SIRT1) protein levels. When cells were treated with vehicle control (VC), LN alone (LN; 100μmol/L) or in combination with α-ESA (LN+α-ESA; 75+25μmol/L) for 24h, acetylation of forkhead box protein O1 was decreased, while the NAD(+)/NADH ratio, mRNA levels of NAMPT and PTGR1 and enzyme activity of nicotinamide phosphoribosyltransferase were increased by LN+α-ESA treatment compared to treatment with LN alone, suggesting that α-ESA activates SIRT1 by increasing NAD(+) synthesis and NAD(P)H consumption. The antisteatosis effect of α-ESA was confirmed in mice treated with a high-sucrose diet supplemented with 1% α-ESA for 5weeks. We conclude that α-ESA favorably affects hepatic lipid metabolism by increasing cellular NAD(+)/NADH ratio and activating PPARα, AMPK and SIRT1 signaling pathways. PMID:27260465

  1. New Millisecond Isomer Lifetime Measurements at LANSCE

    SciTech Connect

    Devlin, M. Nelson, R.O.; Fotiades, N.; O'Donnell, J.M.

    2014-06-15

    New half-life measurements have been made of the millisecond isomers {sup 71m}Ge, {sup 114m2}I, {sup 208m}Bi, {sup 88m1}Y, {sup 88m2}Y, and {sup 75m}As populated in neutron-induced reactions. These measurements were made using the unique time structure of the LANSCE/WNR neutron source, by observing the γ-ray decays of the isomers during the time between the LANSCE proton macropulses. Two different LANSCE proton beam time structures were used. The GEANIE array of HPGe detectors was used to detect the γ-ray decays.

  2. 'Melatonin isomer' in wine is not an isomer of the melatonin but tryptophan-ethylester.

    PubMed

    Gardana, Claudio; Iriti, Marcello; Stuknytė, Milda; De Noni, Ivano; Simonetti, Paolo

    2014-11-01

    Melatonin is a neurohormone, chronobiotic, and antioxidant compound found in wine and deriving directly from grapes and/or synthesized by yeast during alcoholic fermentation. In addition, a melatonin isomer has been detected in different foods, wine among them. The special interest for melatonin isomer related to the fact that it was found in greater quantities than melatonin and probably shares some of its biological properties. Despite this, its chemical structure has not yet been defined; although some researchers hypothesize, it could be melatonin with the ethylacetamide group shifted into position N1. Thus, the aim of our study was to identify the structures of the melatonin isomer. For this purpose, melatonin and melatonin isomer in Syrah wine were separated chromatographically by a sub-2 μm particle column and detected by tandem mass spectrometry. The sample was then purified and concentrated by solid-phase extraction, hydrolyzed with alkali or esterase, and substrates and products quantified by UPLC-MS/MS. Moreover, melatonin, melatonin isomer, and their product ions were evaluated by high-resolution mass spectrometry. The amount of melatonin isomer and melatonin in the wine was 84 ± 4 and 3 ± 0 ng/mL, respectively. In the solutions, containing diluted alkali or esterase, melatonin isomer was hydrolyzed in about 8 min. Correspondingly, tryptophan was detected, and its amount increased and reached the maximum concentration in about 8 min. Melatonin concentration was not affected by diluted alkali or esterase. The fragmentation pattern of melatonin isomer was different from that of melatonin but comparable to that of tryptophan-ethylester. Finally, the so-called melatonin isomer identity was verified by cochromatography with authentic standard of tryptophan-ethylester. PMID:25251161

  3. Isomer Studies for Nuclei near the Proton Drip Line in the Mass 130-160 Region

    SciTech Connect

    Cullen, D. M.; Mason, P. J. R.; Khan, S.; Kishada, A. M.; Varley, B. J.; Rigby, S. V.; Scholey, C.; Greenlees, P.; Rahkila, P.; Jones, P. M.; Julin, R.; Juutinen, S.; Leino, M.; Leppaenen, A. P.; Nyman, M.; Uusitalo, J.; Grahn, T.; Nieminen, P.; Pakarinen, J.

    2007-11-30

    This report details the status of an experimental research programme which has studied isomeric states in the mass 130-160 region of the nuclear chart. Several new isomers have been established and characterised near the proton drip line using a recoil isomer tagging technique at the University of Jyvaeskylae, Finland. The latest experiments have been performed with a modified setup where the standard GREAT focal-plane double-sided silicon-strip detector was changed to a dual multi-wire proportional-counter arrangement. This new setup has improved capability for short-lived isomer studies where high focal-plane rates can be tolerated. The results of key recent experiments for nuclei situated above ({sup 153}Yb,{sup 152}Tm) and below ({sup 136}Pm,{sup 142}Tb) the N = 82 shell gap were presented along with an interpretation for the isomers. Finally, the future prospects of the technique, using an isomer-tagged differential-plunger setup, were discussed. This technique will be capable of establishing the deformation of the states above the isomers and will aid in the process of assigning underlying single-particle configurations to the isomeric states.

  4. FT-Raman spectroscopy of structural isomers of Pt(II) complex PtCl2(PEt3)2

    NASA Astrophysics Data System (ADS)

    Bhatt, Himal; Deo, M. N.; Vishwakarma, S. R.; Bajaj, Naini; Sharma, Surinder M.

    2015-06-01

    We report here the detailed spectroscopic aspects of the structural isomers of Pt(II) complex PtCl2(P(C2H5)3)2 using FT-Raman spectroscopy. A comparison of the structural contraction instigated by lowering the temperature up to liquid nitrogen temperature in the cis and trans isomers has been presented. The lattice region lying in the far infrared region upto 50cm-1 has been analyzed in detail to probe the structural modifications. It was found that the ambient temperature lower symmetry structure of the cis isomer is preserved at low temperatures. The trans isomer, stabilizing in a high symmetry structure at room temperature, transforms to a low symmetry structure on lowering the temperature, which can be attributed to a loss of inversion symmetry of the trans isomer.

  5. Ototoxicity of the three xylene isomers in the rat.

    PubMed

    Maguin, Katy; Lataye, Robert; Campo, Pierre; Cossec, Benoît; Burgart, Manuella; Waniusiow, Delphine

    2006-01-01

    Numerous experiments have shown that the aromatic solvents can affect the auditory system in the rat, the cochlea being targeted first. Solvents differ in cochleotoxic potency: for example, styrene is more ototoxic than toluene or xylenes. The goal of this study was to determine the relative ototoxicity of the three isomers of xylene (o-, m- or p-xylene). Moreover, by dosing with the two urinary metabolites of xylene, methylhippuric (MHAs) and mercapturic acids (MBAs), this study points toward a causal relationship between the cochleotoxic effects and potential reactive intermediates arising from the biotransformation of the parent molecules. Separate groups of rats were exposed by inhalation to one isomer following this schedule: 1800 ppm, 6 h/d, 5 d/wk for 3 wk. Auditory thresholds were determined with brainstem-auditory evoked potentials. Morphological analysis of the organ of Corti was performed by counting both sensory and spiral ganglion cells. Among the three isomers, only p-xylene was cochleotoxic. A 39-dB permanent threshold shift was obtained over the tested frequencies range from 8 to 20 kHz. Whereas outer hair cells were largely injured, no significant morphological change was observed within spiral ganglia. The concentrations of urinary p-, o- or m-MHA were greater (p-MHA: 33.2 g/g; o-MHA: 7.8 g/g; m-MHA: 20.4 g/g) than those obtained for MBAs (p-MBA: 0.04 g/g; o-MBA: 6.2 g/g; m-MBA: 0.03 g/g). Besides, there is a large difference between o-MBA (6.2 g/g) and p-MBA (0.04 g/g). As a result, since the cysteine conjugates are not determinant in the ototoxic process of xylenes, the location of the methyl groups around the benzene nucleus could play a key role. PMID:17045780

  6. Introduction of Branching Degrees of Octane Isomers.

    PubMed

    Perdih, Anton

    2016-01-01

    The concept of branching degrees is introduced. In the case of octane isomers it is derived from the values of a set of their physicochemical properties, calculating for each isomer the average of the normalized values and these averages are defined as branching degrees of octane isomers. The sequence of these branching degrees of octane isomers does not differ much from the »regular« one defined earlier. 2,2-Dimethylhexane appears to be less branched than 3,4-dimethylhexane and 3-ethyl, 2-methylpentane, whereas 2,3,4-trimethylpentane appears to be less branched than 3-ethyl, 3-methylpentane. While the increasing number of branches gives rise to increasing branching degrees, the peripheral position of branches and the separation between branches decreases the value of the branching degree. The central position of branches increases it. A bigger branch increases it more than a smaller one. The quantification of these structural features and their correlations with few indices is given as well. PMID:27333567

  7. Dietary Trans Fatty Acids and Cardiovascular Disease Risk: Past and Present

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dietary trans double bond fatty acids have been associated with increased risk of cardiovascular disease. There are two main sources of dietary trans fatty acids: meat and dairy fats, and partially-hydrogenated oils. Due to a number of factors, including changes in federal labeling requirements fo...

  8. Rapid progression and mortality of lysosomal acid lipase deficiency presenting in infants

    PubMed Central

    Jones, Simon A.; Valayannopoulos, Vassili; Schneider, Eugene; Eckert, Stephen; Banikazemi, Maryam; Bialer, Martin; Cederbaum, Stephen; Chan, Alicia; Dhawan, Anil; Di Rocco, Maja; Domm, Jennifer; Enns, Gregory M.; Finegold, David; Gargus, J. Jay; Guardamagna, Ornella; Hendriksz, Christian; Mahmoud, Iman G.; Raiman, Julian; Selim, Laila A.; Whitley, Chester B.; Zaki, Osama; Quinn, Anthony G.

    2016-01-01

    Purpose: The purpose of this study was to enhance understanding of lysosomal acid lipase deficiency (LALD) in infancy. Genet Med 18 5, 452–458. Methods: Investigators reviewed medical records of infants with LALD and summarized data for the overall population and for patients with and without early growth failure (GF). Kaplan–Meier survival analyses were conducted for the overall population and for treated and untreated patients. Genet Med 18 5, 452–458. Results: Records for 35 patients, 26 with early GF, were analyzed. Prominent symptom manifestations included vomiting, diarrhea, and steatorrhea. Median age at death was 3.7 months; estimated probability of survival past age 12 months was 0.114 (95% confidence interval (CI): 0.009-0.220). Among patients with early GF, median age at death was 3.5 months; estimated probability of survival past age 12 months was 0.038 (95% CI: 0.000-0.112). Treated patients (hematopoietic stem cell transplant (HSCT), n = 9; HSCT and liver transplant, n = 1) in the overall population and the early GF subset survived longer than untreated patients, but survival was still poor (median age at death, 8.6 months). Genet Med 18 5, 452–458. Conclusions: These data confirm and expand earlier insights on the progression and course of LALD presenting in infancy. Despite variations in the nature, onset, and severity of clinical manifestations, and treatment attempts, clinical outcome was poor. Genet Med 18 5, 452–458. PMID:26312827

  9. Diversity of acetic acid bacteria present in healthy grapes from the Canary Islands.

    PubMed

    Valera, Maria José; Laich, Federico; González, Sara S; Torija, Maria Jesús; Mateo, Estibaliz; Mas, Albert

    2011-11-15

    The identification of acetic acid bacteria (AAB) from sound grapes from the Canary Islands is reported in the present study. No direct recovery of bacteria was possible in the most commonly used medium, so microvinifications were performed on grapes from Tenerife, La Palma and Lanzarote islands. Up to 396 AAB were isolated from those microvinifications and identified by 16S rRNA gene sequencing and phylogenetic analysis. With this method, Acetobacter pasteurianus, Acetobacter tropicalis, Gluconobacter japonicus and Gluconacetobacter saccharivorans were identified. However, no discrimination between the closely related species Acetobacter malorum and Acetobacter cerevisiae was possible. As previously described, 16S-23S rRNA gene internal transcribed spacer (ITS) region phylogenetic analysis was required to classify isolates as one of those species. These two species were the most frequently occurring, accounting for more than 60% of the isolates. For typing the AAB isolates, both the Enterobacterial Repetitive Intergenic Consensus (ERIC)-PCR and (GTG)5-PCR techniques gave similar resolution. A total of 60 profiles were identified. Thirteen of these profiles were found in more than one vineyard, and only one profile was found on two different islands (Tenerife and La Palma). PMID:21903289

  10. Refractory status epilepticus and glutamic acid decarboxylase antibodies in adults: presentation, treatment and outcomes.

    PubMed

    Khawaja, Ayaz M; Vines, Brannon L; Miller, David W; Szaflarski, Jerzy P; Amara, Amy W

    2016-03-01

    Glutamic acid decarboxylase antibodies (GAD-Abs) have been implicated in refractory epilepsy. The association with refractory status epilepticus in adults has been rarely described. We discuss our experience in managing three adult patients who presented with refractory status epilepticus associated with GAD-Abs. Case series with retrospective chart and literature review. Three patients without pre-existing epilepsy who presented to our institution with generalized seizures between 2013 and 2014 were identified. Seizures proved refractory to first and second-line therapies and persisted beyond 24 hours. Patient 1 was a 22-year-old female who had elevated serum GAD-Ab titres at 0.49 mmol/l (normal: <0.02) and was treated with multiple immuno- and chemotherapies, with eventual partial seizure control. Patient 2 was a 61-year-old black female whose serum GAD-Ab titre was 0.08 mmol/l. EEG showed persistent generalized periodic discharges despite maximized therapy with anticonvulsants but no immunotherapy, resulting in withdrawal of care and discharge to nursing home. Patient 3 was a 50-year-old black female whose serum GAD-Ab titre was 0.08 mmol/l, and was discovered to have pulmonary sarcoidosis. Treatment with steroids and intravenous immunoglobulin resulted in seizure resolution. Due to the responsiveness to immunotherapy, there may be an association between GAD-Abs and refractory seizures, including refractory status epilepticus. Causation cannot be established since GAD-Abs may be elevated secondary to concurrent autoimmune diseases or formed de novo in response to GAD antigen exposure by neuronal injury. Based on this report and available literature, there may be a role for immuno- and chemotherapy in the management of refractory status epilepticus associated with GAD-Abs. PMID:26878120

  11. Photodynamics of potent antioxidants: ferulic and caffeic acids.

    PubMed

    Horbury, Michael D; Baker, Lewis A; Quan, Wen-Dong; Greenough, Simon E; Stavros, Vasilios G

    2016-07-14

    The dynamics of ferulic acid (3-(4-hydroxy-3-methoxyphenyl)-2-propenoic acid) and caffeic acid (3-(3,4-dihydroxyphenyl)-2-propenoic acid) in acetonitrile, dioxane and water at pH 2.2 following photoexcitation to the first excited singlet state are reported. These hydroxycinnamic acids display both strong ultraviolet absorption and potent antioxidant activity, making them promising sunscreen components. Ferulic and caffeic acids have previously been shown to undergo trans-cis photoisomerization via irradiation studies, yet time-resolved measurements were unable to observe formation of the cis-isomer. In the present study, we are able to observe the formation of the cis-isomer as well as provide timescales of relaxation following initial photoexcitation. PMID:27310931

  12. The combustion kinetics of octane isomers

    SciTech Connect

    Burcat, A.; Pitz, W.J.; Westbrook, C.K.

    1990-03-29

    Shock tube experiments provide conditions for testing kinetic models that are unique, since this is the only common environment in which initiation reactions, primarily the unimolecular decompositions of the fuel, play an important role. At least two factors are known to be very important, the fuel molecule size and its precise structure. Iso-octane has an octane number of 100, which reflects the relative difficulty with which iso-octanes/air mixtures ignite. Conversely, C{sub 8}H{sub 18}, the straight chain n-octane, ignites very easily, with an octane number of approximately zero. The present work addresses the importance of fuel structure for large hydrocarbon fuels, by comparing the ignition of isomers of octane under shock tube conditions. Ignition delay times were performed with n-octane, a linear chain molecular with only primary and secondary C-H bonds, 2-3-4-trimethyl-pentane has a highly branched molecule and contains only primary and tertiary C-H bonds, and iso-octane a molecule which includes a mixture of primary, secondary, and tertiary C-H bonds. Also 1-octene, a simple straight chain alkene was included. The experiments were run in a single pulse stainless steel shock tube. 475 shocks were performed. They were spread as follows: (1) 164 experiments with 1-octene (C{sub 8}H{sub 16}). (2) 137 experiments with 2,2,4 tri-methyl pentane. (3) 30 experiments with 2,3,4 tri-methyl pentane. (4) 144 experiments with n-octane. 3 refs.

  13. Excitation of nuclear isomers by X rays from laser plasma

    SciTech Connect

    Andreev, Aleksandr A; Karpeshin, F; Trzhaskovskaya, M B; Platonov, Konstantin Yu; Rozhdestvenskii, Yu V

    2010-06-23

    The possibility of obtaining isomer nuclei is studied by the example of the molybdenum isomer {sup 93}Mo upon irradiation of a niobium {sup 93}Nb target by {approx}50-J, 100-fs laser pulses. It is shown that the modern laser technique allows production of isomer nuclei by accelerated protons and radiative de-excitation of isomer nuclear states by thermal or line X-rays from laser plasma. (interaction of laser radiation with matter. laser plasma)

  14. Positional Isomers of Aspirin Are Equally Potent in Inhibiting Colon Cancer Cell Growth: Differences in Mode of Cyclooxygenase Inhibition

    PubMed Central

    Kodela, Ravinder; Chattopadhyay, Mitali; Goswami, Satindra; Gan, Zong Yuan; Rao, Praveen P. N.; Nia, Kamran V.; Velázquez-Martínez, Carlos A.

    2013-01-01

    We compared the differential effects of positional isomers of acetylsalicylic acid (o-ASA, m-ASA, and p-ASA) on cyclooxygenase (COX) inhibition, gastric prostaglandin E2 (PGE2), malondialdehyde, tumor necrosis factor-alpha (TNF-α) levels, superoxide dismutase (SOD) activity, human adenocarcinoma colon cancer cell growth inhibition, cell proliferation, apoptosis, and cell-cycle progression. We also evaluated the gastric toxicity exerted by ASA isomers. All ASA isomers inhibit COX enzymes, but only the o-ASA exerted an irreversible inhibitory profile. We did not observe a significant difference between ASA isomers in their ability to decrease the in vivo synthesis of PGE2 and SOD activity. Furthermore, all isomers increased the levels of gastric and TNF-α when administered orally at equimolar doses. We observed a dose-dependent cell growth inhibitory effect; the order of potency was p-ASA > m-ASA ≈ o-ASA. There was a dose-dependent decrease in cell proliferation and an increase in apoptosis, with a concomitant Go/G1 arrest. The ulcerogenic profile of the three ASA isomers showed a significant difference between o-ASA (aspirin) and its two positional isomers when administered orally at equimolar doses (1 mmol/kg); the ulcer index (UI) for o-ASA indicated extensive mucosal injury (UI = 38), whereas m-ASA and p-ASA produced a significantly decreased toxic response (UI = 12 and 8, respectively) under the same experimental conditions. These results suggest that the three positional isomers of ASA exert practically the same biologic profile in vitro and in vivo but showed different safety profiles. The mechanism of gastric ulcer formation exerted by aspirin and its two isomers warrants a more detailed and thorough investigation. PMID:23349335

  15. Elongated shape isomers in the Ar36 nucleus

    NASA Astrophysics Data System (ADS)

    Cseh, József; Darai, Judit; Sciani, Wagner; Otani, Yul; Lépine-Szily, Alinka; Benjamim, Elisangela A.; Chamon, Luiz Carlos; Filho, Rubens Lichtenthäler

    2009-09-01

    A recent analysis of the C12+Mg24 scattering [W. Sciani , Phys. Rev. C 80, 034319 (2009)] suggests the existence of a hyperdeformed band in the Ar36 nucleus, completely in line with the predictions of α [W. D. M. Rae and A. C. Merchant, Phys. Lett. B279, 207 (1992)] and binary cluster calculations [J. Cseh , Phys. Rev. C 70, 034311 (2004)]. Here we review the structural understanding of the superdeformed and the hyperdeformed states of Ar36 and present new results on the shape isomers as well. Special attention is paid to the clusterization of these states, which indicates the appropriate reaction channels for their formation.

  16. Fatty acid composition of lipids present in selected lichenized fungi: a chemotyping study.

    PubMed

    Sassaki, G L; Cruz, L M; Gorin, P A; Lacomini, M

    2001-02-01

    The total-lipid composition of 21 lichens of the ascomycetous genera Cladonia (11) and Cladina (1) of the family Cladoniacea, Cladia (1), Parmotrema (3), Ramalina (2), Leptogium (1), Cetraria (1), and the basidiomycetous genus Dictyonema (1) was determined. Analyses of those of Dictyonema glabratum were carried out with a total extract and those obtained after successive extractions with various solvents. Each extract was partitioned between n-heptane/isopropanol and 1 M sulfuric acid, giving triglycerides (TG) in the upper phase. Extracts were methanolyzed and the resulting methyl esters were analyzed by gas chromatography-mass spectrometry. Methanolyzates of TG unexpectedly contained esters of 9-oxodecanoic, 9-methyl-tetradecanoic, 6-methyl-tetradecanoic, 3-hydroxy-decanoic, nonanedioic, and decanedioic acids, as well as common fatty acids. Fatty acid methyl ester profiles from the lichens were submitted to cluster analysis, and the resulting dendogram showed a cluster consistent with Cladonia spp., suggesting an efficient aid to lichen taxonomy. The total carbohydrate content of each lipid extract was determined by a modified phenol-sulfuric acid method, which compensated for the presence of pigments. PMID:11269697

  17. Investigating the Minimum Energy Principle in Searches for New Molecular Species—The Case of H2C3O Isomers

    NASA Astrophysics Data System (ADS)

    Loomis, Ryan A.; McGuire, Brett A.; Shingledecker, Christopher; Johnson, Chelen H.; Blair, Samantha; Robertson, Amy; Remijan, Anthony J.

    2015-01-01

    Recently, Lattelais et al. have interpreted aggregated observations of molecular isomers to suggest that there exists a "minimum energy principle," such that molecular formation will favor more stable molecular isomers for thermodynamic reasons. To test the predictive power of this principle, we have fully characterized the spectra of the three isomers of C3H2O toward the well-known molecular region Sgr B2(N). Evidence for the detection of the isomers cyclopropenone (c-C3H2O) and propynal (HCCCHO) is presented, along with evidence for the non-detection of the lowest zero-point energy isomer, propadienone (CH2CCO). We interpret these observations as evidence that chemical formation pathways, which may be under kinetic control, have a more pronounced effect on final isomer abundances than thermodynamic effects such as the minimum energy principle.

  18. INVESTIGATING THE MINIMUM ENERGY PRINCIPLE IN SEARCHES FOR NEW MOLECULAR SPECIES—THE CASE OF H{sub 2}C{sub 3}O ISOMERS

    SciTech Connect

    Loomis, Ryan A.; McGuire, Brett A.; Remijan, Anthony J.; Shingledecker, Christopher; Johnson, Chelen H.; Blair, Samantha; Robertson, Amy

    2015-01-20

    Recently, Lattelais et al. have interpreted aggregated observations of molecular isomers to suggest that there exists a ''minimum energy principle'', such that molecular formation will favor more stable molecular isomers for thermodynamic reasons. To test the predictive power of this principle, we have fully characterized the spectra of the three isomers of C{sub 3}H{sub 2}O toward the well-known molecular region Sgr B2(N). Evidence for the detection of the isomers cyclopropenone (c-C{sub 3}H{sub 2}O) and propynal (HCCCHO) is presented, along with evidence for the non-detection of the lowest zero-point energy isomer, propadienone (CH{sub 2}CCO). We interpret these observations as evidence that chemical formation pathways, which may be under kinetic control, have a more pronounced effect on final isomer abundances than thermodynamic effects such as the minimum energy principle.

  19. Search for a ''3.5-eV isomer'' in {sup 229}Th in a hollow-cathode electric discharge

    SciTech Connect

    Inamura, T. T.; Haba, H.

    2009-03-15

    A hollow-cathode electric discharge, a well-established source in optical spectroscopy, was used to populate the ''3.5-eV isomer'' in {sup 229}Th with use of nuclear excitation by electron transition (NEET). The radiochemically purest {sup 229}Th sample was loaded into the hollow cathode in which the electric discharge excited the {sup 229}Th to atomic states some of which could be expected to lie close to the excitation energy of the sought isomer. Although there remain some uncertainties, our experiments indicate that the isomer was populated by NEET and its {alpha} decay observed after switching off the electric discharge with a corresponding isomer half-life 1 min < or approx. T{sub 1/2}{sup m} < or approx. 3 min. From the present NEET condition, the isomer appears to lie between 3 eV and 7 eV. The probability of the isomer population by NEET is discussed.

  20. Accurate ab initio Quartic Force Fields of Cyclic and Bent HC2N Isomers

    NASA Technical Reports Server (NTRS)

    Inostroza, Natalia; Huang, Xinchuan; Lee, Timothy J.

    2012-01-01

    Highly correlated ab initio quartic force field (QFFs) are used to calculate the equilibrium structures and predict the spectroscopic parameters of three HC2N isomers. Specifically, the ground state quasilinear triplet and the lowest cyclic and bent singlet isomers are included in the present study. Extensive treatment of correlation effects were included using the singles and doubles coupled-cluster method that includes a perturbational estimate of the effects of connected triple excitations, denoted CCSD(T). Dunning s correlation-consistent basis sets cc-pVXZ, X=3,4,5, were used, and a three-point formula for extrapolation to the one-particle basis set limit was used. Core-correlation and scalar relativistic corrections were also included to yield highly accurate QFFs. The QFFs were used together with second-order perturbation theory (with proper treatment of Fermi resonances) and variational methods to solve the nuclear Schr dinger equation. The quasilinear nature of the triplet isomer is problematic, and it is concluded that a QFF is not adequate to describe properly all of the fundamental vibrational frequencies and spectroscopic constants (though some constants not dependent on the bending motion are well reproduced by perturbation theory). On the other hand, this procedure (a QFF together with either perturbation theory or variational methods) leads to highly accurate fundamental vibrational frequencies and spectroscopic constants for the cyclic and bent singlet isomers of HC2N. All three isomers possess significant dipole moments, 3.05D, 3.06D, and 1.71D, for the quasilinear triplet, the cyclic singlet, and the bent singlet isomers, respectively. It is concluded that the spectroscopic constants determined for the cyclic and bent singlet isomers are the most accurate available, and it is hoped that these will be useful in the interpretation of high-resolution astronomical observations or laboratory experiments.

  1. Idiopathic bile acid malabsorption--a review of clinical presentation, diagnosis, and response to treatment.

    PubMed Central

    Williams, A J; Merrick, M V; Eastwood, M A

    1991-01-01

    Between 1982 and 1989, the seven day retention of 75SeHCAT was measured in 181 patients with chronic diarrhoea that remained unexplained after full investigation. Altogether 121 of the 181 had a seven day 75SeHCAT retention greater than or equal to 15% and thus had no evidence of abnormal bile acid turnover. Twenty one had a seven day 75SeHCAT retention greater than or equal to 10% but less than 15%. Their clinical features were typical of the irritable bowel syndrome, and none of eight treated with cholestyramine showed symptomatic improvement. Sixteen patients had a seven day retention greater than or equal to 5% and less than 10%, six of whom had improved symptoms after treatment with bile acid chelating agents. The remaining 23 patients had a 75SeHCAT retention of less than 5% at seven days and responded to bile acid chelators. This group had a characteristic illness with intermittent watery diarrhoea, but no constitutional upset. It was not possible to distinguish the patients with bile acid malabsorption exclusively on the basis of the clinical symptoms and investigations, other than 75SeHCAT retention. We conclude that the measurement of 75SeHCAT retention is useful, appropriate, and necessary in patients with unexplained chronic diarrhoea. PMID:1916479

  2. Label-free direct surface-enhanced Raman scattering (SERS) of nucleic acids (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Guerrini, Luca; Morla-Folch, Judit; Gisbert-Quilis, Patricia; Xie, Hainan; Alvarez-Puebla, Ramon

    2016-03-01

    Recently, plasmonic-based biosensing has experienced an unprecedented level of attention, with a particular focus on the nucleic acid detection, offering efficient solutions to engineer simple, fast, highly sensitive sensing platforms while overcoming important limitations of PCR and microarray techniques. In the broad field of plasmonics, surface-enhanced Raman scattering (SERS) spectroscopy has arisen as a powerful analytical tool for detection and structural characterization of biomolecules. Today applications of SERS to nucleic acid analysis largely rely on indirect strategies, which have been demonstrated very effective for pure sensing purposes but completely dismiss the exquisite structural information provided by the direct acquisition of the biomolecular vibrational fingerprint. Contrarily, direct label-free SERS of nucleic acid shows an outstanding potential in terms of chemical-specific information which, however, remained largely unexpressed mainly because of the inherent poor spectral reproducibility and/or limited sensitivity. To address these limitations, we developed a fast and affordable high-throughput screening direct SERS method for gaining detailed genomic information on nucleic acids (DNA and RNA) and for the characterization and quantitative recognition of DNA interactions with exogenous agents. The simple strategy relies on the electrostatic adhesion of DNA/RNA onto positively-charged silver colloids that promotes the nanoparticle aggregation into stable clusters yielding intense and reproducible SERS spectra at picogram level (i.e. the analysis can be performed without the necessity of amplification steps thus providing realistic direct information of the nucleic acid in its native state). We anticipate this method to gain a vast impact and set of applications in different fields, including medical diagnostics, genomic screening, drug discovery, forensic science and even molecular electronics.

  3. Isomer effects on polyimide properties

    NASA Technical Reports Server (NTRS)

    Stump, B. L.

    1978-01-01

    Thermally stable polyimide polymers were prepared. Parameters explored include asymmetry of substitution, addition of alkyl substituents to an aromatic ring, and an increase in the number of aromatic rings present in the diamine monomer. It is shown that the use of an asymmetrical diamine in the preparation of a polyimide produces a polymer with a markedly lowered glass transition temperature. This is achieved with little or no sacrifice of thermal stability. An alternate approach taken was to prepare imide monomers which are capable of addition-type polymerization.

  4. Isomer Shifts in Solid State Chemistry

    NASA Astrophysics Data System (ADS)

    Wagner, F. E.; Stievano, L.

    The isomer shift of the Mössbauer resonance is a rather unique quantity that cannot be obtained by any of the other techniques used for measuring hyperfine interactions in solids, such as NMR or perturbed angular correlations (TDPAC). It shifts the resonance pattern as a whole without affecting the magnetic dipole and electric quadrupole hyperfine splittings. Methods that measure only these hyperfine splittings are insensitive to the isomer shift. The magnitude of the observed shift is proportional to the product of a nuclear parameter, the change Δ⟨r 2⟩ of the nuclear radius that goes along with the Mössbauer transition, and to an electronic property of the material, the electron density ρ(0) at the Mössbauer nucleus or, more precisely, to the difference Δρ(0) of the electron densities at the Mössbauer nuclei in the materials of which the source and the absorber are made. The electron density at the nucleus is due to s-electrons and, to a lesser extent and mainly in heavy nuclei, to relativistic p1 / 2-electrons. All the other electrons have a vanishing density inside the nucleus and do not contribute. Thus, to a very good accuracy, the Mössbauer isomer shift enables one to obtain information on the s-electron density at the Mössbauer nuclei in solids.

  5. 21 CFR 184.1061 - Lactic acid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ....1061 Lactic acid. (a) Lactic acid (C3H6O3, CAS Reg. Nos.: dl mixture, 598-82-3; l-isomer, 79-33-4; d-isomer, 10326-41-7), the chemical 2-hydroxypropanoic acid, occurs naturally in several foods. It...

  6. Silica sol assisted chromatographic NMR spectroscopy for resolution of trans- and cis-isomers.

    PubMed

    Yang, Ying; Wu, Rui; Huang, Shaohua; Bai, Zhengwu

    2016-04-01

    Chromatographic NMR spectroscopy can separate the mixtures of species with significantly different molecular size, but generally fails for isomeric species. Herein, we reported the resolution of trans- and cis-isomers and their structural analogue, which are different in molecular shapes, but similar in mass, were greatly enhanced in the presence of silica sol. The mixtures of maleic acid, fumaric acid and succinic acid, and the mixtures of trans- and cis-1,2-cyclohexanedicarboxylic acids, were distinguished by virtue of their different degrees of interaction with silica sol. Moreover, we found mixed solvents could improve the spectral resolution of DOSY spectra of mixtures. PMID:26942864

  7. Silica sol assisted chromatographic NMR spectroscopy for resolution of trans- and cis-isomers

    NASA Astrophysics Data System (ADS)

    Yang, Ying; Wu, Rui; Huang, Shaohua; Bai, Zhengwu

    2016-04-01

    Chromatographic NMR spectroscopy can separate the mixtures of species with significantly different molecular size, but generally fails for isomeric species. Herein, we reported the resolution of trans- and cis-isomers and their structural analogue, which are different in molecular shapes, but similar in mass, were greatly enhanced in the presence of silica sol. The mixtures of maleic acid, fumaric acid and succinic acid, and the mixtures of trans- and cis-1,2-cyclohexanedicarboxylic acids, were distinguished by virtue of their different degrees of interaction with silica sol. Moreover, we found mixed solvents could improve the spectral resolution of DOSY spectra of mixtures.

  8. Interstellar Isomers: The Importance of Bonding Energy Differences

    NASA Technical Reports Server (NTRS)

    Remijan, Anthony J.; Hollis, J. M.; Lovas, F. J.; Plusquellic, D. F.; Jewell, P. R.

    2005-01-01

    We present strong detections of methyl cyanide (CH3CN), vinyl cyanide (CH2CHCN), ethyl cyanide (CH3CH2CN) and cyanodiacetylene (HC4CN) molecules with the Green Bank Telescope (GBT) toward the Sgr B2(N) molecular cloud. Attempts to detect the corresponding isocyanide isomers were only successful in the case of methyl isocyanide (CH3NC) for its J(sub K) = 1(sub 0) - 0(sub 0) transition, which is the first interstellar report of this line. To determine the spatial distribution of CH3NC, we used archival Berkeley-Illinois-Maryland Association (BIMA) array data for the J(sub K) = 1(sub 0) - 0(sub 0) transitions but no emission was detected. From ab initio calculations, the bonding energy difference between the cyanide and isocyanide molecules is greater than 8500 per centimeter (greater than 12,000 K). Thus, cyanides are the more stable isomers and would likely be formed more preferentially over their isocyanide counterparts. That we detect CH3NC emission with a single antenna (Gaussian beamsize(omega(sub B))=1723 arcsec(sup 2)) but not with an interferometer (omega(sub b)=192 arcsec(sup 2)), strongly suggests that CH3NC has a widespread spatial distribution toward the Sgr B2(N) region. Other investigators have shown that CH3CN is present both in the LMH hot core of Sgr B2(N) and in the surrounding medium, while we have shown that CH3NC appears to be deficient in the LMH hot core. Thus, largescale, non-thermal processes in the surrounding medium may account for the conversion of CH3CN to CH3NC while the LMH hot core, which is dominated by thermal processes, does not produce a significant amount of CH3NC. Ice analog experiments by other investigators have shown that radiation bombardment of CH3CN can produce CH3NC, thus supporting our observations. We conclude that isomers separated by such large bonding energy differences are distributed in different interstellar environments, making the evaluation of column density ratios between such isomers irrelevant unless it can

  9. Application of Roof-Shape Amines as Chiral Solvating Agents for Discrimination of Optically Active Acids by NMR Spectroscopy: Study of Match-Mismatch Effect and Crystal Structure of the Diastereomeric Salts.

    PubMed

    Gupta, Riddhi; Gonnade, Rajesh G; Bedekar, Ashutosh V

    2016-09-01

    Optically active roof-shape amines were prepared and scanned as chiral solvating agents to study molecular recognition of acids by NMR analysis. Three types of amines were studied to establish a match-mismatch effect for structurally diverse acid analytes. Single-crystal X-ray diffraction analysis was performed on the diastereomeric salts of roof-shape amines and both isomers of mandelic acid to establish molecular conformation and correlate the absolute configuration with the observed NMR shift. The present system also recognizes the two isomers of weakly acidic BINOL and its derivatives. PMID:27484455

  10. Production of organic acids by periplasmic enzymes present in free and immobilized cells of Zymomonas mobilis.

    PubMed

    Malvessi, Eloane; Carra, Sabrina; Pasquali, Flávia Cristina; Kern, Denise Bizarro; da Silveira, Mauricio Moura; Ayub, Marco Antônio Záchia

    2013-01-01

    In this work the periplasmic enzymatic complex glucose-fructose oxidoreductase (GFOR)/glucono-δ-lactonase (GL) of permeabilized free or immobilized cells of Zymomonas mobilis was evaluated for the bioconversion of mixtures of fructose and different aldoses into organic acids. For all tested pairs of substrates with permeabilized free-cells, the best enzymatic activities were obtained in reactions with pH around 6.4 and temperatures ranging from 39 to 45 °C. Decreasing enzyme/substrate affinities were observed when fructose was in the mixture with glucose, maltose, galactose, and lactose, in this order. In bioconversion runs with 0.7 mol l(-1) of fructose and with aldose, with permeabilized free-cells of Z. mobilis, maximal concentrations of the respective aldonic acids of 0.64, 0.57, 0.51, and 0.51 mol l(-1) were achieved, with conversion yields of 95, 88, 78, and 78 %, respectively. Due to the important applications of lactobionic acid, the formation of this substance by the enzymatic GFOR/GL complex in Ca-alginate-immobilized cells was assessed. The highest GFOR/GL activities were found at pH 7.0-8.0 and temperatures of 47-50 °C. However, when a 24 h bioconversion run was carried out, it was observed that a combination of pH 6.4 and temperature of 47 °C led to the best results. In this case, despite the fact that Ca-alginate acts as a barrier for the diffusion of substrates and products, maximal lactobionic acid concentration, conversion yields and specific productivity similar to those obtained with permeabilized free-cells were achieved. PMID:23053345

  11. Survey of perfluoroalkyl acids (PFAAs) and their precursors present in Japanese consumer products.

    PubMed

    Ye, Feng; Zushi, Yasuyuki; Masunaga, Shigeki

    2015-05-01

    Perfluoroalkyl acids (PFAAs) and their precursors have been used in various consumer products. However, limited information regarding their occurrence and concentration levels in products is available. In this study, we investigated 18 PFAAs and 14 PFAA precursors in various categories of consumer products purchased in Japan. Relatively high total concentrations of PFAAs and their precursors were found in sprays for fabrics and textiles (acid (PFOS), N-methyl perfluorooctane sulfonamidoethanol (MeFOSE) was detected in a higher frequency (8%) and in greater concentrations (acids (PFCAs) (carbon chain length⩾7) were also detected in greater concentrations than short chain PFCAs (⩽6). This result suggests that consumer products are one of the important sources of long-chain PFCAs in the environment. PMID:25753850

  12. CuCl2 for the isolation of a broad array of endohedral fullerenes containing metallic, metallic carbide, metallic nitride, and metallic oxide clusters, and separation of their structural isomers.

    PubMed

    Stevenson, Steven; Rottinger, Khristina A

    2013-08-19

    A typical arc-synthesis generates many types of fullerenes and endohedrals. Resulting soot extracts contain a complex mixture of >50 types of fullerenes, metallofullerenes, and their structural isomers. Prior to application development, novel separation methods are required to fractionate this rich array of metallic, metallic carbide, metallic nitride, and metallic oxide endohedrals, all of which can be present in a single, soot extract. Herein, we report the discovery of CuCl2 as a Lewis acid that will selectively precipitate only the more reactive members of each of these endohedral families. The more reactive Sc4O2@Ih-C80, Sc3C2@Ih-C80, and Sc3N@D3h-C78 endohedrals are quickly removed from extracts to greatly decrease the number of endohedrals present in a sample. Experiments indicate that enrichment factors of several orders of magnitude can be achieved within minutes of reaction time. CuCl2 also has sufficient selectivity to resolve and separate structural isomers, as demonstrated with Er2@C82 (isomer I, Cs(6)-C82 versus isomer III). The selective complexation of CuCl2 with fullerenes can be correlated to their first oxidation potential. We estimate a significantly lower threshold of precipitation for CuCl2 (<0.19 V) compared to stronger Lewis acids. Fullerenes and metallofullerenes having first oxidation potentials above 0.19 V tend to remain unreacted in solution. In contrast, species with first oxidation potentials below 0.19 V (vs Fc/Fc(+)) precipitate via complexation, and are easily decomplexed. CuCl2 is compared to Lewis acids having higher precipitation thresholds (e.g., FeCl3) in our goal to predict a priori which endohedrals would remain in solution versus which endohedral species would complex and precipitate. The ability to predict endohedral precipitation a priori is beneficial to the design of purification strategies for metallofullerenes. PMID:23952569

  13. Experimental and theoretical cross sections for positron scattering from the pentane isomers

    NASA Astrophysics Data System (ADS)

    Chiari, L.; Zecca, A.; Blanco, F.; García, G.; Brunger, M. J.

    2016-02-01

    Isomerism is ubiquitous in chemistry, physics, and biology. In atomic and molecular physics, in particular, isomer effects are well known in electron-impact phenomena; however, very little is known for positron collisions. Here we report on a set of experimental and theoretical cross sections for low-energy positron scattering from the three structural isomers of pentane: normal-pentane, isopentane, and neopentane. Total cross sections for positron scattering from normal-pentane and isopentane were measured at the University of Trento at incident energies between 0.1 and 50 eV. Calculations of the total cross sections, integral cross sections for elastic scattering, positronium formation, and electronic excitations plus direct ionization, as well as elastic differential cross sections were computed for all three isomers between 1 and 1000 eV using the independent atom model with screening corrected additivity rule. No definitive evidence of a significant isomer effect in positron scattering from the pentane isomers appears to be present.

  14. Elucidation of Drug Metabolite Structural Isomers Using Molecular Modeling Coupled with Ion Mobility Mass Spectrometry.

    PubMed

    Reading, Eamonn; Munoz-Muriedas, Jordi; Roberts, Andrew D; Dear, Gordon J; Robinson, Carol V; Beaumont, Claire

    2016-02-16

    Ion mobility-mass spectrometry (IM-MS) in combination with molecular modeling offers the potential for small molecule structural isomer identification by measurement of their gas phase collision cross sections (CCSs). Successful application of this approach to drug metabolite identification would facilitate resource reduction, including animal usage, and may benefit other areas of pharmaceutical structural characterization including impurity profiling and degradation chemistry. However, the conformational behavior of drug molecules and their metabolites in the gas phase is poorly understood. Here the gas phase conformational space of drug and drug-like molecules has been investigated as well as the influence of protonation and adduct formation on the conformations of drug metabolite structural isomers. The use of CCSs, measured from IM-MS and molecular modeling information, for the structural identification of drug metabolites has also been critically assessed. Detection of structural isomers of drug metabolites using IM-MS is demonstrated and, in addition, a molecular modeling approach has been developed offering rapid conformational searching and energy assessment of candidate structures which agree with experimental CCSs. Here it is illustrated that isomers must possess markedly dissimilar CCS values for structural differentiation, the existence and extent of CCS differences being ionization state and molecule dependent. The results present that IM-MS and molecular modeling can inform on the identity of drug metabolites and highlight the limitations of this approach in differentiating structural isomers. PMID:26752623

  15. Assessment of the in vivo genotoxicity of isomers of dinitrotoluene using the alkaline Comet and peripheral blood micronucleus assays.

    PubMed

    Lent, Emily May; Crouse, Lee C B; Quinn, Michael J; Wallace, Shannon M

    2012-02-18

    Dinitrotoluene (DNT) is a nitroaromatic explosive that exists as six isomers; two major isomers (2,4- and 2,6-DNT) and four minor isomers (2,3-, 2,5-, 3,4-, and 3,5-DNT). DNT has been found in soil, surface water, and groundwater near ammunition production plants. The major isomers of DNT are classified as "likely to cause cancer in humans."In vitro studies have provided conflicting data regarding the genotoxicity of the minor isomers. Studies indicate that metabolism in the gut and liver are necessary to convert DNT to genotoxic compounds. As such, in the present study the genotoxicity of isomers of DNT was assessed using two in vivo genotoxicity assays. The Comet assay was used to detect DNA damage in liver cells from male Sprague-Dawley rats following oral exposure (14-day) to individual isomers of DNT. The micronucleus assay was conducted using flow cytometric analysis to detect chromosomal damage in peripheral blood. Treatment with 2,3-, 3,4-, 2,4-, 2,5- and 3,5-DNT did not induce DNA damage in liver cells or increase the frequency of micronucleated reticulocytes (MN-RET) in peripheral blood at the doses tested. Treatment with 2,6-DNT induced DNA damage in liver tissue at all doses tested, but did not increase the frequency of micronucleated reticulocytes (MN-RET) in peripheral blood. Thus, 2,4-DNT and the minor isomers were not genotoxic under these test conditions, while 2,6-DNT was genotoxic in the target tissue, the liver. These results support previous research which indicated that the hepatocarcinogenicity of technical grade DNT (TG-DNT) could be attributed to the 2,6-DNT isomer. PMID:22155124

  16. Acid rain monitoring in East-Central Florida from 1977 to present

    NASA Technical Reports Server (NTRS)

    Madsen, B. C.; Kheoh, T.; Hinkle, C. R.; Dreschel, T. W.

    1990-01-01

    Rainfall has been collected on the University of Central Florida campus and at the Kennedy Space Center over a 12 year period. The chemical composition has been determined and summarized by monthly, annual periods, and for the entire 12 year period at both locations. The weighted average pH at each site is 4.58; however, annual weighted average pH has been equal to or above the 12 year average during six of the past eight years. Nitrate concentrations have increased slightly during recent years while excess sulfate concentrations have remained below the 12 year weighted average during six of the past seven years. Stepwise regression suggests that sulfate, nitrate, ammonium ion and calcium play major roles in the description of rainwater acidity. Annual acid deposition and annual rainfall have varied from 20 to 50 meg/(m(exp 2) year) and 100 to 180 cm/year, respectively. Sea salt comprises at least 25 percent of the total ionic composition.

  17. Portable, Battery Operated Capillary Electrophoresis with Optical Isomer Resolution Integrated with Ionization Source for Mass Spectrometry.

    PubMed

    Moini, Mehdi; Rollman, Christopher M

    2016-03-01

    We introduce a battery operated capillary electrophoresis electrospray ionization (CE/ESI) source for mass spectrometry with optical isomer separation capability. The source fits in front of low or high resolution mass spectrometers similar to a nanospray source with about the same weight and size. The source has two high voltage power supplies (±25 kV HVPS) capable of operating in forward or reverse polarity modes and powered by a 12 V rechargeable lithium ion battery with operation time of ~10 h. In ultrafast CE mode, in which short narrow capillaries (≤15 μm i.d., 15-25 cm long) and field gradients ≥1000 V/cm are used, peak widths at the base are <1 s wide. Under these conditions, the source provides high resolution separation, including optical isomer resolution in ~1 min. Using a low resolution mass spectrometer (LTQ Velos) with a scan time of 0.07 s/scan, baseline separation of amino acids and their optical isomers were achieved in ~1 min. Moreover, bovine serum albumin (BSA) was analyzed in ~1 min with 56% coverage using the data-dependent MS/MS. Using a high resolution mass spectrometer (Thermo Orbitrap Elite) with 15,000 resolution, the fastest scan time achieved was 0.15 s, which was adequate for CE-MS analysis when optical isomer separation is not required or when the optical isomers were well separated. Figures of merit including a detection limit of 2 fmol and linear dynamic range of two orders of magnitude were achieved for amino acids. PMID:26644308

  18. Conformational preferences and synthesis of isomers Z and E of oxazole-dehydrophenylalanine.

    PubMed

    Staś, Monika; Bujak, Maciej; Broda, Małgorzata A; Siodłak, Dawid

    2016-05-01

    Dehydrophenylalanine, ΔPhe, is the most commonly studied α,β-dehydroamino acid. In nature, further modifications of the α,β-dehydroamino acids were found, for example, replacement of the C-terminal amide group by oxazole ring. The conformational properties of oxazole-dehydrophenylalanine residue (ΔPhe-Ozl), both isomers Z and E, were investigated. To determine all possible conformations, theoretical calculations were performed using Ac-(Z/E)-ΔPhe-Ozl(4-Me) model compounds at M06-2X/6-31++G(d,p) level of theory. Ac-(Z/E)-ΔPhe-Ozl-4-COOEt compounds were synthesized and the conformational preferences of each isomer, Z and E, were investigated using FTIR and NMR-NOE in solutions of increasing polarity (CHCl3 , DMSO-d6). The solid-state low-temperature structures of Ac-(Z)-ΔPhe-Ozl-4-COOEt and its intermediate analog Ac-(Z)-ΔPhe-Ozn(4-OH)-4-COOEt were also determined. In a weakly polar environment, the ΔPhe-Ozl residue has a tendency to adopt the conformation β2 with the calculated φ and ψ angles of -127° and 0° for the isomer Z and -170° and 26° for the isomer E. The increase of environment polarity favors the helical conformation α and the beta-turn like conformation β, but the conformation β2 seems to be still accessible. The (E)-ΔPhe-Ozl residue can be obtained from the isomer Z in photoisomerization reaction. However, hydroxyl-oxazoline-dehydrophenylalanine ΔPhe-Ozn(4-OH) decomposes in such conditions. Alternatively, (E)-ΔPhe-NH2 can be applied as a substrate in the Hantzsch reaction. © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 283-294, 2016. PMID:27061820

  19. Portable, Battery Operated Capillary Electrophoresis with Optical Isomer Resolution Integrated with Ionization Source for Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Moini, Mehdi; Rollman, Christopher M.

    2016-03-01

    We introduce a battery operated capillary electrophoresis electrospray ionization (CE/ESI) source for mass spectrometry with optical isomer separation capability. The source fits in front of low or high resolution mass spectrometers similar to a nanospray source with about the same weight and size. The source has two high voltage power supplies (±25 kV HVPS) capable of operating in forward or reverse polarity modes and powered by a 12 V rechargeable lithium ion battery with operation time of ~10 h. In ultrafast CE mode, in which short narrow capillaries (≤15 μm i.d., 15-25 cm long) and field gradients ≥1000 V/cm are used, peak widths at the base are <1 s wide. Under these conditions, the source provides high resolution separation, including optical isomer resolution in ~1 min. Using a low resolution mass spectrometer (LTQ Velos) with a scan time of 0.07 s/scan, baseline separation of amino acids and their optical isomers were achieved in ~1 min. Moreover, bovine serum albumin (BSA) was analyzed in ~1 min with 56% coverage using the data-dependent MS/MS. Using a high resolution mass spectrometer (Thermo Orbitrap Elite) with 15,000 resolution, the fastest scan time achieved was 0.15 s, which was adequate for CE-MS analysis when optical isomer separation is not required or when the optical isomers were well separated. Figures of merit including a detection limit of 2 fmol and linear dynamic range of two orders of magnitude were achieved for amino acids.

  20. Unequivocal glycyrrhizin isomer determination and comparative in vitro bioactivities of root extracts in four Glycyrrhiza species

    PubMed Central

    Farag, Mohamed A.; Porzel, Andrea; Wessjohann, Ludger A.

    2014-01-01

    Glycyrrhiza glabra, commonly known as licorice, is a popular herbal supplement used for the treatment of chronic inflammatory conditions and as sweetener in the food industry. This species contains a myriad of phytochemicals including the major saponin glycoside glycyrrhizin (G) of Glycyrrhetinic acid (GA) aglycone. In this study, 2D-ROESY NMR technique was successfully applied for distinguishing 18α and 18β glycyrrhetinic acid (GA). ROESY spectra acquired from G. glabra, Glycyrrhiza uralensis and Glycyrrhiza inflata crude extracts revealed the presence of G in its β-form. Anti-inflammatory activity of four Glycyrrhiza species, G, glabra, G. uralensis, G. inflata, and G. echinata roots was assessed against COX-1 inhibition revealing that phenolics rather than glycyrrhizin are biologically active in this assay. G. inflata exhibits a strong cytotoxic effect against PC3 and HT29 cells lines, whereas other species are inactive. This study presents an effective NMR method for G isomer assignment in licorice extracts that does not require any preliminary chromatography or any other purification step. PMID:25685548

  1. Identification of L-Methionine-S-Sulfoximine as the Convulsant Isomer of Methionine Sulfoximine*

    PubMed Central

    Rowe, W. Bruce; Meister, Alton

    1970-01-01

    The convulsant agent methionine sulfoximine inhibits brain glutamine synthetase irreversibly and the inhibitor becomes bound to the active site of the enzyme as methionine sulfoximine phosphate. Only one of the four isomers of methionine sulfoximine, L-methionine-S-sulfoximine, inhibits glutamine synthetase. In the present work, D-methionine-SR-sulfoximine, and highly purified preparations of L-methionine-S-sulfoximine and L-methionine-R-sulfoximine were tested in mice for convulsant activity; only L-methionine-S-sulfoximine produced convulsions. The finding that only one of the four optical isomers of methionine sulfoximine induces convulsions, and that only this same isomer inhibits glutamine synthetase, lends support to the conclusion that these two effects of methionine sulfoximine are closely connected. PMID:4393740

  2. Reduction of MTT to Purple Formazan by Vitamin E Isomers in the Absence of Cells

    PubMed Central

    Lim, Su-Wen; Loh, Hwei-San; Ting, Kang-Nee; Bradshaw, Tracey Dawn; Allaudin, Zeenathul Nazariah

    2015-01-01

    The yellow tetrazolium salt 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) is widely used to determine cell viability in cell proliferation and cytotoxic assays. MTT is reduced by metabolically active cells to form an insoluble purple formazan product that is quantifiable by spectrophotometry. It is the most common and direct assay for cell viability. However, in this present study, we demonstrated that the vitamin E isomers α-β-γ-δ-tocotrienols and α-tocopherol were able to reduce MTT into a formazan product, despite the absence of living cells. For comparison, a second method for determining cell viability, which is the neutral red uptake assay, was used in parallel with the MTT assay. The results showed that neutral red did not interact with the vitamin E isomers. Our findings suggest that the MTT assay is not suitable for studying the proliferative effects of vitamin E isomers on cell growth. PMID:26868595

  3. In vivo formation of polyphosphoinositide isomers and association with progression of murine polycystic kidney disease.

    PubMed

    Aukema, H M; Chapkin, R S; Tomobe, K; Takahashi, H; Holub, B J

    1992-08-01

    Polyphosphoinositide isomers have been demonstrated to be important mediators of cell proliferation in vitro. The present study demonstrates, for the first time, the in vivo formation of the novel isomer, phosphatidylinositol(3)phosphate, in the kidney and liver of intact animals following intraperitoneal administration of [3H]myo-inositol. The formation of renal [3H]phosphatidylinositol(3)phosphate relative to total [3H]phosphatidylinositol-phosphate was positively correlated with cyst proliferation and renal enlargement in a murine model of polycystic kidney disease. Furthermore, despite no difference in the formation of renal [3H]phosphatidylinositol(4)phosphate, a markedly lower accumulation (by 48%) of [3H]phosphatidylinositol(4,5)bisphosphate was observed in the diseased animals as compared to controls. These results indicate that further studies on the in vivo formation of specific polyphosphoinositide isomers in disease states characterized by abnormal growth and oncogene expression are warranted. PMID:1327862

  4. Glycolaldehyde, methyl formate and acetic acid adsorption and thermal desorption from interstellar ices

    NASA Astrophysics Data System (ADS)

    Burke, Daren J.; Puletti, Fabrizio; Brown, Wendy A.; Woods, Paul M.; Viti, Serena; Slater, Ben

    2015-02-01

    We have undertaken a detailed investigation of the adsorption, desorption and thermal processing of the astrobiologically significant isomers glycolaldehyde, acetic acid and methyl formate. Here, we present the results of laboratory infrared and temperature programmed desorption (TPD) studies of the three isomers from model interstellar ices adsorbed on a carbonaceous dust grain analogue surface. Laboratory infrared data show that the isomers can be clearly distinguished on the basis of their infrared spectra, which has implications for observations of interstellar ice spectra. Laboratory TPD data also show that the three isomers can be distinguished on the basis of their thermal desorption behaviour. In particular, TPD data show that the isomers cannot be treated the same way in astrophysical models of desorption. The desorption of glycolaldehyde and acetic acid from water-dominated ices is very similar, with desorption being mainly dictated by water ice. However, methyl formate also desorbs from the surface of the ice, as a pure desorption feature, and therefore desorbs at a lower temperature than the other two isomers. This is more clearly indicated by models of the desorption on astrophysical time-scales corresponding to the heating rate of 25 and 5 M⊙ stars. For a 25 M⊙ star, our model shows that a proportion of the methyl formate can be found in the gas phase at earlier times compared to glycolaldehyde and acetic acid. This has implications for the observation and detection of these molecules, and potentially explains why methyl formate has been observed in a wider range of astrophysical environments than the other two isomers.

  5. Gamma-ray spectroscopy of the ^238U shape isomer.

    NASA Astrophysics Data System (ADS)

    Hauschild, K.; Bauer, R. W.; Becker, J. A.; Bernstein, L. A.; Britt, H. C.; Younes, W.; Fotiades, N.

    1997-04-01

    The γ--rays de--exciting the fission isomers ^236U and ^238U are very different despite similar excitation energies, lifetimes and low--lying yrast structures. The predominant γ--ray decay branch for ^236U^m is a 1.783 MeV E1 transition (J. Schirmer, et al., Phys. Rev. Lett. 63), 2196 (1989); and Refs. therein., while ^238U^m is depopulated by a 2.513 MeV E2 γ-ray (J. Kantele, et al., Phys. Rev. C 29), 1693 (1984); and Refs. therein.. Approximately 65% of the γ--branch de-exciting ^238U^m remains to be identified. To determine the multipolarity of the remaining γ-branch out of ^238U^m we used the Gammasphere array at LBNL and the ^238U(d,pn) reaction at Ed = 20 MeV. A search for excited states in the 2^nd well has also been conducted. Preliminary results will be presented, and the γ--decay of the shape isomers discussed in context with the recent A ~190 SD decay--out results (T. L. Khoo, et al., Phys. Rev. Lett. 76), 1583 (1996); A. Lopez-Martens, et al., Phys. Lett. B380, 18 (1996); K. Hauschild, et al., submitted to Phys. Rev. C (1996)..

  6. Isom's thickness noise for axial and centrifugal subsonic fans

    NASA Astrophysics Data System (ADS)

    Khelladi, S.; Kouidri, S.; Rey, R.

    2008-06-01

    The thickness noise predicted by the Ffowcs Williams and Hawkings (FW&H) equation depends on the normal velocity vn which is very sensitive to the meshing size. Isom showed that in a far field a monopolar source is equivalent to a dipolar source induced by a uniform distribution of the load on the entire moving surface. Consequently, the calculation of the thickness noise becomes completely independent of the normal velocity vn. Its expression, as suggested by Farassat, is for any moving surface. The main objective of this work is to determine a specific expression of Isom's thickness noise in time and frequency domains for axial and centrifugal subsonic fans. The proposed form of the thickness noise enables to highlight the effect of each geometrical parameter of the fan on the overall thickness noise, on the one hand, and presents a fast computational mean and low memory storage capability since the acoustic pressure in the frequency domain is calculated for only one blade, on the other.

  7. Isomer ratio measurements as a probe of the dynamics of breakup and incomplete fusion

    SciTech Connect

    Gasques, L. R.; Dasgupta, M.; Hinde, D. J.; Peatey, T.; Diaz-Torres, A.; Newton, J. O.

    2006-12-15

    The incomplete fusion mechanism following breakup of {sup 6,7}Li and {sup 9}Be projectiles incident on targets of {sup 209}Bi and {sup 208}Pb is investigated through isomer ratio measurements for the {sup 212}At and {sup 211}Po products. The phenomenological analysis presented in this paper indicates that incomplete fusion brings relatively more angular momentum into the system than equivalent reactions with a direct beam of the fused fragment. This is attributed to the trajectories of breakup fragments. Calculations with a 3D classical trajectory model support this. Isomer ratio measurements for incomplete fusion reactions can provide a test of new theoretical models of breakup and fusion.

  8. CD1c bypasses lysosomes to present a lipopeptide antigen with 12 amino acids

    PubMed Central

    Young, David C.; De Jong, Annemieke; Vazquez, Jenny; Cheng, Tan-Yun; Talekar, Rahul; Barral, Duarte C.; León, Luis; Brenner, Michael B.; Katz, Joel T.; Riese, Richard; Ruprecht, Ruth M.; O'Connor, Peter B.; Costello, Catherine E.; Porcelli, Steven A.; Briken, Volker

    2009-01-01

    The recent discovery of dideoxymycobactin (DDM) as a ligand for CD1a demonstrates how a nonribosomal lipopeptide antigen is presented to T cells. DDM contains an unusual acylation motif and a peptide sequence present only in mycobacteria, but its discovery raises the possibility that ribosomally produced viral or mammalian proteins that commonly undergo lipidation might also function as antigens. To test this, we measured T cell responses to synthetic acylpeptides that mimic lipoproteins produced by cells and viruses. CD1c presented an N-acyl glycine dodecamer peptide (lipo-12) to human T cells, and the response was specific for the acyl linkage as well as the peptide length and sequence. Thus, CD1c represents the second member of the CD1 family to present lipopeptides. lipo-12 was efficiently recognized when presented by intact cells, and unlike DDM, it was inactivated by proteases and augmented by protease inhibitors. Although lysosomes often promote antigen presentation by CD1, rerouting CD1c to lysosomes by mutating CD1 tail sequences caused reduction in lipo-12 presentation. Thus, although certain antigens require antigen processing in lysosomes, others are destroyed there, providing a hypothesis for the evolutionary conservation of large CD1 families containing isoforms that survey early endosomal pathways. PMID:19468063

  9. Separation of steroid isomers by ion mobility mass spectrometry.

    PubMed

    Ahonen, Linda; Fasciotti, Maíra; Gennäs, Gustav Boije Af; Kotiaho, Tapio; Daroda, Romeu J; Eberlin, Marcos; Kostiainen, Risto

    2013-10-01

    Ion mobility mass spectrometry performed in a compact traveling wave cell (TWIM-MS) is shown to provide a reliable, fast and repeatable method to separate derivatized steroid isomers. Three steroid isomer pairs were analyzed in their native form and as their p-toluenesulfonyl isocyanate derivatives. The native steroids were separated from each other, but no separation could be attained for the isomers. The derivatized steroid isomers were, however, properly separated by TWIM-MS with peak-to-peak resolutions close to or as high as baseline resolution (Rp-p=0.77-1.08). PMID:23992881

  10. A practical guide to the isolation, analysis and identification of conjugated linoleic acid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural and synthetic conjugated linoleic acids (CLA) are reputed to have therapeutic properties that are specific to particular geometrical and positional isomers. Analysis of these has presented unique problems that have brought forward distinctive solutions, especially the use of gas chromatogra...

  11. Retinoic Acid-Treated Pluripotent Stem Cells Undergoing Neurogenesis Present Increased Aneuploidy and Micronuclei Formation

    PubMed Central

    Sartore, Rafaela C.; Campos, Priscila B.; Trujillo, Cleber A.; Ramalho, Bia L.; Negraes, Priscilla D.; Paulsen, Bruna S.; Meletti, Tamara; Costa, Elaine S.; Chicaybam, Leonardo; Bonamino, Martin H.; Ulrich, Henning; Rehen, Stevens K.

    2011-01-01

    The existence of loss and gain of chromosomes, known as aneuploidy, has been previously described within the central nervous system. During development, at least one-third of neural progenitor cells (NPCs) are aneuploid. Notably, aneuploid NPCs may survive and functionally integrate into the mature neural circuitry. Given the unanswered significance of this phenomenon, we tested the hypothesis that neural differentiation induced by all-trans retinoic acid (RA) in pluripotent stem cells is accompanied by increased levels of aneuploidy, as previously described for cortical NPCs in vivo. In this work we used embryonal carcinoma (EC) cells, embryonic stem (ES) cells and induced pluripotent stem (iPS) cells undergoing differentiation into NPCs. Ploidy analysis revealed a 2-fold increase in the rate of aneuploidy, with the prevalence of chromosome loss in RA primed stem cells when compared to naïve cells. In an attempt to understand the basis of neurogenic aneuploidy, micronuclei formation and survivin expression was assessed in pluripotent stem cells exposed to RA. RA increased micronuclei occurrence by almost 2-fold while decreased survivin expression by 50%, indicating possible mechanisms by which stem cells lose their chromosomes during neural differentiation. DNA fragmentation analysis demonstrated no increase in apoptosis on embryoid bodies treated with RA, indicating that cell death is not the mandatory fate of aneuploid NPCs derived from pluripotent cells. In order to exclude that the increase in aneuploidy was a spurious consequence of RA treatment, not related to neurogenesis, mouse embryonic fibroblasts were treated with RA under the same conditions and no alterations in chromosome gain or loss were observed. These findings indicate a correlation amongst neural differentiation, aneuploidy, micronuclei formation and survivin downregulation in pluripotent stem cells exposed to RA, providing evidence that somatically generated chromosomal variation accompanies

  12. Isoaspartic acid is present at specific sites in myelin basic protein from multiple sclerosis patients: could this represent a trigger for disease onset?

    PubMed

    Friedrich, Michael G; Hancock, Sarah E; Raftery, Mark J; Truscott, Roger J W

    2016-01-01

    Multiple sclerosis (MS) is associated with breakdown of the myelin sheath that coats neurons in the central nervous system. The cause of MS is not known, although the pathogenesis involves destruction of myelin by the immune system. It was the aim of this study to examine the abundant myelin protein, myelin basic protein (MBP), to determine if there are sites of modification that may be characteristic for MS. MBP from the cerebellum was examined from controls and MS patients across the age range using mass spectrometry and amino acid analysis. Amino acid racemization data indicated that myelin basic protein is long-lived and proteomic analysis of MBP showed it to be highly modified. A common modification of MBP was racemization of Asp and this was significantly greater in MS patients. In long-lived proteins, L-Asp and L-Asn can racemize to three other isomers, D-isoAsp, L-isoAsp and D-Asp and this is significant because isoAsp formation in peptides renders them immunogenic.Proteomic analysis revealed widespread modifications of MBP with two surface regions that are altered in MS. In particular, isoAsp was significantly elevated at these sites in MS patients. The generation of isoAsp could be responsible for eliciting an immune response to modified MBP and therefore be implicated in the etiology of MS. PMID:27519525

  13. Fundamental Issues Related to the Origin of Melatonin and Melatonin Isomers during Evolution: Relation to Their Biological Functions

    PubMed Central

    Tan, Dun-Xian; Zheng, Xiaodong; Kong, Jin; Manchester, Lucien C.; Hardeland, Ruediger; Kim, Seok Joong; Xu, Xiaoying; Reiter, Russel J.

    2014-01-01

    Melatonin and melatonin isomers exist and/or coexist in living organisms including yeasts, bacteria and plants. The levels of melatonin isomers are significantly higher than that of melatonin in some plants and in several fermented products such as in wine and bread. Currently, there are no reports documenting the presence of melatonin isomers in vertebrates. From an evolutionary point of view, it is unlikely that melatonin isomers do not exist in vertebrates. On the other hand, large quantities of the microbial flora exist in the gut of the vertebrates. These microorganisms frequently exchange materials with the host. Melatonin isomers, which are produced by these organisms inevitably enter the host’s system. The origins of melatonin and its isomers can be traced back to photosynthetic bacteria and other primitive unicellular organisms. Since some of these bacteria are believed to be the precursors of mitochondria and chloroplasts these cellular organelles may be the primary sites of melatonin production in animals or in plants, respectively. Phylogenic analysis based on its rate-limiting synthetic enzyme, serotonin N-acetyltransferase (SNAT), indicates its multiple origins during evolution. Therefore, it is likely that melatonin and its isomer are also present in the domain of archaea, which perhaps require these molecules to protect them against hostile environments including extremely high or low temperature. Evidence indicates that the initial and primary function of melatonin and its isomers was to serve as the first-line of defence against oxidative stress and all other functions were acquired during evolution either by the process of adoption or by the extension of its antioxidative capacity. PMID:25207599

  14. 27 CFR 21.120 - Nitropropane, mixed isomers of.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Nitropropane, mixed isomers of. 21.120 Section 21.120 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE... Denaturants § 21.120 Nitropropane, mixed isomers of. (a) Nitropropane content. A minimum of 94 percent...

  15. 27 CFR 21.120 - Nitropropane, mixed isomers of.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Nitropropane, mixed isomers of. 21.120 Section 21.120 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE... Denaturants § 21.120 Nitropropane, mixed isomers of. (a) Nitropropane content. A minimum of 94 percent...

  16. 27 CFR 21.120 - Nitropropane, mixed isomers of.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Nitropropane, mixed isomers of. 21.120 Section 21.120 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE... Denaturants § 21.120 Nitropropane, mixed isomers of. (a) Nitropropane content. A minimum of 94 percent...

  17. 27 CFR 21.120 - Nitropropane, mixed isomers of.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Nitropropane, mixed isomers of. 21.120 Section 21.120 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE... Denaturants § 21.120 Nitropropane, mixed isomers of. (a) Nitropropane content. A minimum of 94 percent...

  18. 27 CFR 21.120 - Nitropropane, mixed isomers of.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Nitropropane, mixed isomers of. 21.120 Section 21.120 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE... Denaturants § 21.120 Nitropropane, mixed isomers of. (a) Nitropropane content. A minimum of 94 percent...

  19. Pseudo-discontinuities in the isomer shift near magnetic transitions

    NASA Astrophysics Data System (ADS)

    Kolk, B.; Hall, D. B.; Zheng, Y.; Lumetta, J. T.

    1983-12-01

    It is shown that a relatively small non-linear behavior of the velocity drive system used in Mössbauer effect studies yields pseudo-discontinuities in the isomer shift near the critical temperature T c of a magnetic-paramagnetic transition. The anomaly of the57Fe isomer shift in iron is attributed to this effect.

  20. Acid, basic, and neutral peptidases present different profiles in chromophobe renal cell carcinoma and in oncocytoma.

    PubMed

    Blanco, Lorena; Larrinaga, Gorka; Pérez, Itxaro; López, José I; Gil, Javier; Agirregoitia, Ekaitz; Varona, Adolfo

    2008-04-01

    Renal cell carcinomas (RCCs) are neoplasias with high prevalence and mortality. We previously reported that several peptidases may be involved in the pathophysiology of clear cell renal cell carcinoma (CCRCC). Now, to gain insight into the reasons that lead the various RCC types to behave very differently with regard to aggressiveness and response to anticancer treatments, we analyzed subsets of chromophobe renal cell carcinoma (ChRCC), and renal oncocytoma (RO), a benign tumor; as well as different grades and stages of CCRCCs. Particulate APN, APB, and APA activities were decreased in both ChRCC and RO (tumor vs. nontumor tissues). Interestingly, activities were downregulated in a tumor-type specific way and the intensities of the decreases were stronger in the benign tumor than in the malignant type. Moreover, when two key histopathological parameters for tumor prognosis (high vs. low stage and grade) were analyzed, increases of activity were also observed in several of these cell surface peptidases (APN, APB). Some soluble activities (APB, Asp-AP) were also downregulated in the RCCs. With respect to genetic expression, PSA and APN were in a positive correlation related to their activities in both ChRCC and RO; but not APB, Asp-AP, APA, and PGI. These results may suggest an involvement of several peptidases in the pathophysiology of renal cancer, since they presented different patterns of activity and expression in tumors with different behaviors. PMID:18216146

  1. Lutein and Zeaxanthin Isomers in Eye Health and Disease.

    PubMed

    Mares, Julie

    2016-07-17

    Current evidence suggests lutein and its isomers play important roles in ocular development in utero and throughout the life span, in vision performance in young and later adulthood, and in lowering risk for the development of common age-related eye diseases in older age. These xanthophyll (oxygen-containing) carotenoids are found in a wide variety of vegetables and fruits, and they are present in especially high concentrations in leafy green vegetables. Additionally, egg yolks and human milk appear to be bioavailable sources. The prevalence of lutein, zeaxanthin, and meso-zeaxanthin in supplements is increasing. Setting optimal and safe ranges of intake requires additional research, particularly in pregnant and lactating women. Accumulating evidence about variable interindividual response to dietary intake of these carotenoids, based on genetic or metabolic influences, suggests that there may be subgroups that benefit from higher levels of intake and/or alternate strategies to improve lutein and zeaxanthin status. PMID:27431371

  2. Elongated shape isomers in the {sup 36}Ar nucleus

    SciTech Connect

    Cseh, Jozsef; Darai, Judit; Sciani, Wagner; Otani, Yul; Lepine-Szily, Alinka; Benjamim, Elisangela A.; Chamon, Luiz Carlos; Filho, Rubens Lichtenthaeler

    2009-09-15

    A recent analysis of the {sup 12}C+{sup 24}Mg scattering [W. Sciani et al., Phys. Rev. C 80, 034319 (2009)] suggests the existence of a hyperdeformed band in the {sup 36}Ar nucleus, completely in line with the predictions of {alpha}[W. D. M. Rae and A. C. Merchant, Phys. Lett. B279, 207 (1992)] and binary cluster calculations [J. Cseh et al., Phys. Rev. C 70, 034311 (2004)]. Here we review the structural understanding of the superdeformed and the hyperdeformed states of {sup 36}Ar and present new results on the shape isomers as well. Special attention is paid to the clusterization of these states, which indicates the appropriate reaction channels for their formation.

  3. Remotely Controlled Isomer Selective Molecular Switching.

    PubMed

    Schendel, Verena; Borca, Bogdana; Pentegov, Ivan; Michnowicz, Tomasz; Kraft, Ulrike; Klauk, Hagen; Wahl, Peter; Schlickum, Uta; Kern, Klaus

    2016-01-13

    Nonlocal addressing-the "remote control"-of molecular switches promises more efficient processing for information technology, where fast speed of switching is essential. The surface state of the (111) facets of noble metals, a confined two-dimensional electron gas, provides a medium that enables transport of signals over large distances and hence can be used to address an entire ensemble of molecules simultaneously with a single stimulus. In this study we employ this characteristic to trigger a conformational switch in anthradithiophene (ADT) molecules by injection of hot carriers from a scanning tunneling microscope (STM) tip into the surface state of Cu(111). The carriers propagate laterally and trigger the switch in molecules at distances as far as 100 nm from the tip location. The switching process is shown to be long-ranged, fully reversible, and isomer selective, discriminating between cis and trans diastereomers, enabling maximum control. PMID:26619213

  4. Isomer ratio calculations using modeled discrete levels

    SciTech Connect

    Gardner, M.A.; Gardner, D.G.; Hoff, R.W.

    1984-10-16

    Isomer ratio calculations were made for the reactions: /sup 175/Lu(n,..gamma..)/sup 176m,g/Lu, /sup 175/Lu(n,2n)/sup 174m,g/Lu, /sup 237/Np(n,2n)/sup 236m,g/Np, /sup 241/Am(n,..gamma..)/sup 242m,g/Am, and /sup 243/Am(n,..gamma..)/sup 244m,g/Am using modeled level structures in the deformed, odd-odd product nuclei. The hundreds of discrete levels and their gamma-ray branching ratios provided by the modeling are necessary to achieve agreement with experiment. Many rotational bands must be included in order to obtain a sufficiently representative selection of K quantum numbers. The levels of each band must be extended to appropriately high values of angular momentum.

  5. Laboratory detection of the elusive HSCO+ isomer.

    PubMed

    McCarthy, M C; Thaddeus, P

    2007-12-14

    The rotational spectrum of protonated carbonyl sulfide, HSCO(+), has now been detected in the centimeter-wave band in a molecular beam by Fourier transform microwave spectroscopy. Rotational and centrifugal distortion constants have been determined from transitions in the K(a)=0 ladder of the normal isotopic species, and DSCO(+) and H(34)SCO(+). HSCO(+) is systematically more abundant by a factor of three than HOCS(+), the isomer obtained by attaching the H(+) to the other end of the molecule, which ab initio calculations long predicted to be higher in energy by 4-5 kcalmol. Because HSCO(+) is comparable in polarity to HOCS(+) and is apparently more stable and because OCS is widely distributed in astronomical sources, HSCO(+) is a good candidate for detection with radio telescopes. PMID:18081381

  6. Nuclear structure and depletion of nuclear isomers using electron linacs

    SciTech Connect

    Carroll, J. J.; Litz, M. S.; Henriquez, S. L.; Burns, D. A.; Netherton, K. A.; Pereira, N. R.; Karamian, S. A.

    2013-04-19

    Long-lived nuclear excited states (isomers) have proven important to understanding nuclear structure. With some isomers having half-lives of decades or longer, and intrinsic energy densities reaching 10{sup 12} J/kg, they have also been suggested for a wide range of applications. The ability to effectively transfer a population of nuclei from an isomer to shorter-lived levels will determine the feasibility of any applications. Here is described a first demonstration of the induced depletion of a population of the 438 year isomer of {sup 108}Ag to its 2.38 min ground state, using 6 MeV bremsstrahlung from a modified medical electron linac. The experiment suggests refinements to be implemented in the future and how a similar approach might be applied to study induced depletion of the 1200 year isomer of {sup 166}Ho.

  7. Experimental and computational investigation of the thermochemistry of the six isomers of dichloroaniline.

    PubMed

    Ribeiro da Silva, Manuel A V; Amaral, Luísa M P F; Gomes, José R B

    2006-07-27

    The standard (p(o) = 0.1 MPa) molar enthalpies of formation of 2,3-, 2,4-, 2,5-, 2,6-, 3,4- and 3,5-dichloroanilines were derived from the standard molar energies of combustion, in oxygen, to yield CO(2)(g), N(2)(g) and HCl.600H(2)O(l), at T = 298.15 K, measured by rotating bomb combustion calorimetry. The Calvet high-temperature vacuum sublimation technique was used to measure the enthalpies of sublimation of the six isomers. These two thermodynamic parameters yielded the standard molar enthalpies of formation of the six isomers of dichloroaniline, in the gaseous phase, at T = 298.15 K. The gas-phase enthalpies of formation were also estimated by G3MP2B3 calculations, which were further extended to the computation of gas-phase acidities, proton affinities, and ionization enthalpies. PMID:16854047

  8. Enhancement in fecal excretion of dioxin isomer in mice by several dietary fibers.

    PubMed

    Aozasa, O; Ohta, S; Nakao, T; Miyata, H; Nomura, T

    2001-10-01

    The effect of increased nutrients (protein, lipid, vitamins and minerals) on dioxin-induced toxic manifestations such as immune suppression, hepatic hypertrophy, splenic atrophy and enzyme induction was investigated in mice after oral administration of 1,2,3,4,7,8-HxCDD (HxCDD) as one of a representative compound of dioxin isomers. Consequently, it appeared that increased minerals and vitamins in the diet prevented immune suppression by HxCDD. In addition, to clarify the additive effect of nutrients and the ability to hasten the excretion of dioxins by dietary fiber, the adsorbing of dioxins by 16 dietary fibers was investigated by in vitro experiment. Among 16 dietary fibers, locust bean gum, pectin, alginic acid, guar gum, chitin and cellulose were effective in binding dioxin isomers. These dietary fibers also enhanced the fecal excretion of HxCDD in mice. PMID:11572611

  9. Toward the laboratory identification of [O,N,S,S] isomers: Implications for biological NO chemistry

    NASA Astrophysics Data System (ADS)

    Ayari, Tarek; Jaidane, Nejm-Eddine; Al Mogren, Muneerah Mogren; Francisco, Joseph S.; Hochlaf, Majdi

    2016-06-01

    Benchmark ab initio calculations are performed to investigate the stable isomers of [O,N,S,S]. These computations are carried out using coupled cluster (RCCSD(T)) and explicitly correlated coupled cluster methods (RCCSD(T)-F12). In addition to the already known cis isomer of SSNO, nine other stable forms are predicted. The most stable isomer is cis-OSNS. Nine structures are chain bent-bent with relatively large dipole moments which make them detectable, as cis-SSNO, by infrared, far-infrared, and microwave spectroscopies. We found also a C2v isomer (NS2O). Since these species are strongly suggested to play an important role as intermediates during the bioactive reaction products of the NO/H2S interaction, the rotational and vibrational spectroscopic parameters are presented to help aid the in vivo identification and assignment of these spectra. Results from this work show that [O,N,S,S] may play key roles during nitric oxide transport and deliver in biological media, as well as, provide an explanation for the weak characteristic of disulfide bridges within proteins.

  10. Infrared spectroscopy of the acetyl cation and its protonated ketene isomer

    NASA Astrophysics Data System (ADS)

    Mosley, J. D.; Young, J. W.; Duncan, M. A.

    2014-07-01

    [C2,H3,O]+ ions are generated with a pulsed discharge in a supersonic expansion containing methyl acetate or acetone. These ions are mass selected and their infrared spectra are recorded via laser photodissociation and the method of argon tagging. Computational chemistry is employed to investigate structural isomers and their spectra. The acetyl cation (CH3CO+) is the global minimum and protonated ketene (CH2COH+) is the next lowest energy isomer (+176.2 kJ/mol). When methyl acetate is employed as the precursor, the infrared spectrum reveals that only the acetyl cation is formed. Partially resolved rotational structure reveals rotation about the C3 axis. When acetone is used as the precursor, acetyl is still the most abundant cation, but there is also a minor component of protonated ketene. Computations reveal a significant barrier to interconversion between the two isomers (+221 kJ/mol), indicating that protonated ketene must be obtained via kinetic trapping. Both isomers may be present in interstellar environments, and their implications for astrochemistry are discussed.

  11. The sim operon facilitates the transport and metabolism of sucrose isomers in Lactobacillus casei ATCC 334.

    PubMed

    Thompson, John; Jakubovics, Nicholas; Abraham, Bindu; Hess, Sonja; Pikis, Andreas

    2008-05-01

    Inspection of the genome sequence of Lactobacillus casei ATCC 334 revealed two operons that might dissimilate the five isomers of sucrose. To test this hypothesis, cells of L. casei ATCC 334 were grown in a defined medium supplemented with various sugars, including each of the five isomeric disaccharides. Extracts prepared from cells grown on the sucrose isomers contained high levels of two polypeptides with M(r)s of approximately 50,000 and approximately 17,500. Neither protein was present in cells grown on glucose, maltose or sucrose. Proteomic, enzymatic, and Western blot analyses identified the approximately 50-kDa protein as an NAD(+)- and metal ion-dependent phospho-alpha-glucosidase. The oligomeric enzyme was purified, and a catalytic mechanism is proposed. The smaller polypeptide represented an EIIA component of the phosphoenolpyruvate-dependent sugar phosphotransferase system. Phospho-alpha-glucosidase and EIIA are encoded by genes at the LSEI_0369 (simA) and LSEI_0374 (simF) loci, respectively, in a block of seven genes comprising the sucrose isomer metabolism (sim) operon. Northern blot analyses provided evidence that three mRNA transcripts were up-regulated during logarithmic growth of L. casei ATCC 334 on sucrose isomers. Internal simA and simF gene probes hybridized to approximately 1.5- and approximately 1.3-kb transcripts, respectively. A 6.8-kb mRNA transcript was detected by both probes, which was indicative of cotranscription of the entire sim operon. PMID:18310337

  12. Toward the laboratory identification of [O,N,S,S] isomers: Implications for biological NO chemistry.

    PubMed

    Ayari, Tarek; Jaidane, Nejm-Eddine; Al Mogren, Muneerah Mogren; Francisco, Joseph S; Hochlaf, Majdi

    2016-06-21

    Benchmark ab initio calculations are performed to investigate the stable isomers of [O,N,S,S]. These computations are carried out using coupled cluster (RCCSD(T)) and explicitly correlated coupled cluster methods (RCCSD(T)-F12). In addition to the already known cis isomer of SSNO, nine other stable forms are predicted. The most stable isomer is cis-OSNS. Nine structures are chain bent-bent with relatively large dipole moments which make them detectable, as cis-SSNO, by infrared, far-infrared, and microwave spectroscopies. We found also a C2v isomer (NS2O). Since these species are strongly suggested to play an important role as intermediates during the bioactive reaction products of the NO/H2S interaction, the rotational and vibrational spectroscopic parameters are presented to help aid the in vivo identification and assignment of these spectra. Results from this work show that [O,N,S,S] may play key roles during nitric oxide transport and deliver in biological media, as well as, provide an explanation for the weak characteristic of disulfide bridges within proteins. PMID:27334171

  13. Infrared spectroscopy of the acetyl cation and its protonated ketene isomer

    SciTech Connect

    Mosley, J. D.; Young, J. W.; Duncan, M. A.

    2014-07-14

    [C{sub 2},H{sub 3},O]{sup +} ions are generated with a pulsed discharge in a supersonic expansion containing methyl acetate or acetone. These ions are mass selected and their infrared spectra are recorded via laser photodissociation and the method of argon tagging. Computational chemistry is employed to investigate structural isomers and their spectra. The acetyl cation (CH{sub 3}CO{sup +}) is the global minimum and protonated ketene (CH{sub 2}COH{sup +}) is the next lowest energy isomer (+176.2 kJ/mol). When methyl acetate is employed as the precursor, the infrared spectrum reveals that only the acetyl cation is formed. Partially resolved rotational structure reveals rotation about the C{sub 3} axis. When acetone is used as the precursor, acetyl is still the most abundant cation, but there is also a minor component of protonated ketene. Computations reveal a significant barrier to interconversion between the two isomers (+221 kJ/mol), indicating that protonated ketene must be obtained via kinetic trapping. Both isomers may be present in interstellar environments, and their implications for astrochemistry are discussed.

  14. Vitamin E and cancer: An insight into the anticancer activities of vitamin E isomers and analogs.

    PubMed

    Constantinou, Constantina; Papas, Andreas; Constantinou, Andreas I

    2008-08-15

    Current observations in the literature suggest that vitamin E may be a suitable candidate for the adjuvant treatment of cancer. Even though historically most research focused on alpha-tocopherol, more recent evidence suggests that the other isomers of vitamin E (beta-, gamma- and delta-tocopherols and alpha-, beta-, gamma- and delta-tocotrienols) differ in their proapoptotic potencies. The main focus of this communication is the current understanding of the molecular mechanisms regulated by vitamin E isomers and their analogs during the induction of apoptosis. This review highlights that the mitochondria are the major target for the induction of apoptosis by vitamin E isomers and analogs and that the various signaling pathways regulated by these agents are likely to contribute towards maximizing the intrinsic pathway of apoptosis triggered initially by the mitochondria. Overall, the presentation of recent studies from the literature in this communication allows the drawing of the following important conclusions: (i) no direct link exists between the antioxidant activity of each isomer/derivative and proapoptotic potency, (ii) tocotrienols are more effective proapoptotic agents than tocopherols, (iii) synthetic modifications of the naturally occurring compounds may improve their apoptotic potency and (iv) vitamin E isomers and derivatives regulate caspase-independent pathways of apoptosis. The latter combined with the evidence presented in this review regarding the additive or synergistic anticarcinogenic effects obtained when vitamin E analogs are used in combination with other cancer chemotherapeutic agents, supports further research to design the most promising vitamin E derivatives and clinically test them in adjuvant chemotherapeutic treatments. PMID:18512238

  15. Removal of co-present chromate and arsenate by zero-valent iron in groundwater with humic acid and bicarbonate.

    PubMed

    Liu, Tongzhou; Rao, Pinhua; Mak, Mark S H; Wang, Peng; Lo, Irene M C

    2009-05-01

    The interactions of co-present Cr(VI) and As(V), and the influences of humic acid and bicarbonate in the process of Cr(VI) and As(V) removal by Fe(0) were investigated in a batch setting using simulated groundwater with 5 mM NaCl, 1 mM Na(2)SO(4), and 0.8 mM CaCl(2) as background electrolytes at an initial pH value of 7. Cr(VI) and As(V) were observed to be subject to different impacts induced by co-existing As(V) or Cr(VI), humic acid and bicarbonate, originating from their distinct removal mechanisms by Fe(0). Cr(VI) removal is a reduction-dominated process, whereas As(V) removal principally involves adsorption onto iron corrosion products. Experimental results showed that Cr(VI) removal was not affected by the presence of As(V) and humic acid. However, As(V) removal appeared to be inhibited by co-present Cr(VI). When the Cr(VI) concentration was 2, 5, and 10 mg/L, in the absence of humic acid and bicarbonate, As(V) removal rate constants were decreased by 27.9%, 49.0%, and 61.2%, respectively, which probably resulted from competition between Cr(VI) and As(V) for adsorption sites of the iron corrosion products. Furthermore, the presence of humic acid significantly varied As(V) removal kinetics by delaying the formation and aggregation of iron hydroxides due to the formation of soluble Fe-humate complexes and stably dispersed fine iron hydroxides colloids. In the presence of bicarbonate, both Cr(VI) and As(V) removal was increased and the inhibitory effect of Cr(VI) on As(V) removal was suppressed, resulting from the buffering effects and the promoted iron corrosion induced by bicarbonate, and the formation of CaCO(3) in solution, which enhanced As(V) adsorption. PMID:19321187

  16. Influence of levels of information as presented by different technologies on students' understanding of acid, base, and ph concepts

    NASA Astrophysics Data System (ADS)

    Nakhleh, Mary B.; Krajcik, Joseph S.

    We investigated how different levels of information presented by various technologies affected secondary students' understanding of acid, base, and pH concepts. Secondary students who were selected for the study had just completed their study of acid-base chemistry. No attempt was made to provide further instruction. We analyzed changes in the understanding of individual students by constructing concept maps from the propositions that the students used in interviews conducted before and after a series of acid-base titrations. After the initial interview, students were divided into three groups. Within each group, students individually performed the same set of titrations using different technologies: chemical indicators, pH meters, and microcomputer-based laboratories (MBL). After the titrations were completed, all students were interviewed again. We found that students using MBL exhibited a larger positive shift in their concept map scores, which indicates a greater differentiation and integration of their knowledge of acids and bases. The chemical indicator students exhibited a more moderate positive shift in their concept map scores, and the pH meter students exhibited a smaller positive shift. We also found that the MBL students constructed more inappropriate links in their concept maps than the chemical indicator or pH meter students. However, we speculate that this increased number of inappropriate links indicates a high level of involvement with the technology. We therefore argue that the level of information offered by the technology affected students' understanding of the chemical concepts.Received: 24 February 1993; Revised: 21 February 1994;

  17. Adsorption of hexane isomers on ion-exchanged mordenite

    SciTech Connect

    Huddersman, K.

    1996-10-01

    To remove lead from petrol and thereby promote a cleaner environment, other means must be found to keep the octane number or anti-knock qualities of the petrol high. It is found that this can be accomplished by increasing the proportion of highly branched chain hydrocarbon isomers in the fuel. This in turn promotes processes for the separation of the hydrocarbon isomers and in the case of hexane, it is an easy matter to separate out n-hexane from the more substituted isomers but it is difficult to separate out the mono- from the di-branched isomers. This work addresses itself to such challenging separations using modified zeolites as the separating agent, and by studying the heats of sorption of these isomers on zeolites using gas chromatographic techniques to find a trend in the potential abilities of these modified zeolites to effect a good separation. In this work mordenite zeolite was modified by a range of double cation exchanges and the resulting modified zeolites were investigated for their ability to sorb the hexane isomers 3-methylpentane and 2,3-dimethylbutane. These two isomers are closely related in size as they both have the same kinetic diameter of 0.56 nm. In this work only heats of sorption have been investigated and measurement of the diffusion coefficients, which also affect the ability of the modified zeolites to act as good separating agents, is currently under investigation.

  18. Comparison of the repeated dose toxicity of isomers of dinitrotoluene.

    PubMed

    Lent, Emily May; Crouse, Lee C B; Quinn, Michael J; Wallace, Shannon M

    2012-03-01

    Dinitrotoluene (DNT) is a nitroaromatic explosive used in propellant mixtures and in the production of plastics. Isomers of DNT were administered daily via oral gavage to male Sprague-Dawley rats for 14 days to determine the subacute toxicity of individual isomers of DNT. The 3,5-DNT isomer was the most toxic isomer, inducing weight loss and mortality within 3 days. Cyanosis and anemia were observed for all isomers. Exposure to 2,4-, 2,6-, and 3,5-DNT resulted in decreased testes mass and degenerative histopathological changes. Increased splenic mass was observed for 2,4-, 2,6-, and 2,5-DNT. Extramedullary hematopoiesis of the spleen was noted for all isomers, while lymphoid hyperplasia of the spleen was noted for all isomers except 2,5-DNT. Increased liver mass was observed for 2,3-DNT and 3,4-DNT. Hepatocellular lesions were observed for 2,6-DNT and 2,4-DNT. Neurotoxic effects were noted for 3,4-DNT, 2,4-DNT, and 3,5-DNT. PMID:22422434

  19. Quantification of the ratio of positional isomer dilinoleoyl-oleoyl glycerols in vegetable oils.

    PubMed

    Jakab, A; Jablonkai, I; Forgács, E

    2003-01-01

    The distribution of fatty acids in a triacylglycerol is of great importance from nutritional, biochemical, quality and technological points of view. The ratio of triacylglycerol positional isomers containing two linoleic acid (18:2) and one oleic acid (18:1) moieties--namely, 1(3),2-dilinoleoyl-3(1)-oleoyl glycerol (LLO) and 1,3-dilinoleoyl-2-oleoyl glycerol (LOL)--were quantified in grape seed, olive, pumpkin seed, soybean, sunflower and wheat germ oils by high-performance liquid chromatography/atmospheric pressure chemical ionization mass spectrometry (HPLC/APCI-MS) in selected ion monitoring (SIM) mode. Relative LOL contents (LOL/(LLO+LOL)) of the oils were calculated from the mass abundances of the [LL]+ and [LO]+ diacylglycerol fragment ions ([M+H-RCOOH]+) using a calibration curve. The calibration curve of the relative diacylglycerol mass abundances was measured in SIM mode. The relative LOL contents were found to be relatively consistent for each oil variety. The relative LOL content in grape seed, sunflower, pumpkin seed, soybean and wheat germ oils accounted for 44.2 +/- 2.6, 26.8 +/- 3.2, 16.7 +/- 4.6, 15.9 +/- 2.9 and 13.9 +/- 4.3%, respectively. Only olive oils contained practically 100% of the LLO isomer. These results indicate that the unsaturated fatty acids such as linoleic and oleic acids have 'non-random' distribution patterns in various oils. PMID:14558129

  20. The impact of technical cashew nut shell liquid on thermally-induced trans isomers in edible oils.

    PubMed

    Guo, Qin; Wang, Feng; He, Fan; Ha, Yi-Ming; Li, Qing-Peng; Jin, Jing; Deng, Zhao-Xuan

    2016-03-01

    The effects of technical cashew nut shell liquid (TCNSL) on the trans isomerization of edible oils during heating are investigated. Edible oils were subjected to thermal treatment at various heating times and temperatures. Our results show that the addition of TCNSL to edible oils at the appropriate concentration during heating suppresses trans fatty acid formation and induces formation of conjugated linoleic acid (CLA) isomers. A concentration of 0.2 % TCNSL demonstrates the best ability to inhibit formation of trans-oleic acid, trans-linoleic acid, and trans-linolenic acid isomers as well as increase the formation of 9 t,11 t-CLA and 10 t,12 t-CLA isomers. Our analysis indicates that the presence of 0.2 % TCNSL in corn oil does not significantly reduce the acid value, but may significantly lower the peroxide value. TCNSL is also observed to have better function compared to Vitamin E (VE) and tertiary butylhydroquinone (TBHQ), indicating that it may be considered an effective additive in edible oils. PMID:27570273

  1. High-spin torus isomers and their precession motions

    NASA Astrophysics Data System (ADS)

    Ichikawa, T.; Matsuyanagi, K.; Maruhn, J. A.; Itagaki, N.

    2014-09-01

    Background: In our previous study, we found that an exotic isomer with a torus shape may exist in the high-spin, highly excited states of Ca40. The z component of the total angular momentum, Jz=60ℏ, of this torus isomer is constructed by totally aligning 12 single-particle angular momenta in the direction of the symmetry axis of the density distribution. The torus isomer executes precession motion with the rigid-body moments of inertia about an axis perpendicular to the symmetry axis. The investigation, however, has been focused only on Ca40. Purpose: We systematically investigate the existence of exotic torus isomers and their precession motions for a series of N =Z even-even nuclei from Si28 to Ni56. We analyze the microscopic shell structure of the torus isomer and discuss why the torus shape is generated beyond the limit of large oblate deformation. Method: We use the cranked three-dimensional Hartree-Fock method with various Skyrme interactions in a systematic search for high-spin torus isomers. We use the three-dimensional time-dependent Hartree-Fock method for describing the precession motion of the torus isomer. Results: We obtain high-spin torus isomers in Ar36,Ca40,Ti44,Cr48, and Fe52. The emergence of the torus isomers is associated with the alignments of single-particle angular momenta, which is the same mechanism as found in Ca40. It is found that all the obtained torus isomers execute the precession motion at least two rotational periods. The moment of inertia about a perpendicular axis, which characterizes the precession motion, is found to be close to the classical rigid-body value. Conclusions: The high-spin torus isomer of Ca40 is not an exceptional case. Similar torus isomers exist widely in nuclei from Ar36 to Fe52 and they execute the precession motion. The torus shape is generated beyond the limit of large oblate deformation by eliminating the 0s components from all the deformed single-particle wave functions to maximize their mutual

  2. Raman spectroscopic analysis of isomers of biliverdin dimethyl ester.

    PubMed

    Matysik, J; Hildebrandt, P; Smit, K; Mark, F; Gärtner, W; Braslavsky, S E; Schaffner, K; Schrader, B

    1997-06-01

    The constitutional isomers of biliverdin dimethyl ester, IX alpha and XIII alpha, were studied by resonance Raman spectroscopy. The far-reaching spectral similarities suggest that despite the different substitution patterns, the compositions of the normal modes are closely related. This conclusion does not hold only for the parent state (ZZZ, sss configuration) but also for the configurational isomers which were obtained upon double-bond photoisomerization. Based on a comparison of the resonance Raman spectra, a EZZ configuration is proposed for one of the two photoisomers of biliverdin dimethyl ester IX alpha, while a ZZE, ssa configuration has been assigned previously to the second isomer. PMID:9226559

  3. Separation and identification of indene–C70 bisadduct isomers

    PubMed Central

    Zhang, Bolong; Subbiah, Jegadesan; Jones, David J

    2016-01-01

    Summary Following an initial work on the isolation of a single geometric isomer from an indene–C70 bisadduct (IC70BA) mixture, we report the full fractionation and identification of the bisadduct species in the material. Eleven fractions of IC70BA isomers were separated by high-performance liquid chromatography. A number of fractions contained relatively pure isomer species and their configuration were deduced using a variety of analytical techniques including 1H and 13C NMR and UV–vis spectroscopy. The electrochemical properties and the organic solar cell device performance were investigated for fractions where a reasonable quantity of sample could be isolated. PMID:27340480

  4. Detection of Actinides via Nuclear Isomer De-Excitation

    SciTech Connect

    Francy, Christopher J.

    2009-07-01

    This dissertation discusses a data collection experiment within the Actinide Isomer Identification project (AID). The AID project is the investigation of an active interrogation technique that utilizes nuclear isomer production, with the goal of assisting in the interdiction of illicit nuclear materials. In an attempt to find and characterize isomers belonging to 235U and its fission fragments, a 232Th target was bombarded with a monoenergetic 6Li ion beam, operating at 45 MeV.

  5. 21 CFR 184.1061 - Lactic acid.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Lactic acid. 184.1061 Section 184.1061 Food and... Substances Affirmed as GRAS § 184.1061 Lactic acid. (a) Lactic acid (C3H6O3, CAS Reg. Nos.: dl mixture, 598-82-3; l-isomer, 79-33-4; d-isomer, 10326-41-7), the chemical 2-hydroxypropanoic acid,...

  6. 21 CFR 184.1061 - Lactic acid.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Lactic acid. 184.1061 Section 184.1061 Food and... Substances Affirmed as GRAS § 184.1061 Lactic acid. (a) Lactic acid (C3H6O3, CAS Reg. Nos.: dl mixture, 598-82-3; l-isomer, 79-33-4; d-isomer, 10326-41-7), the chemical 2-hydroxypropanoic acid,...

  7. 21 CFR 184.1061 - Lactic acid.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Lactic acid. 184.1061 Section 184.1061 Food and... Substances Affirmed as GRAS § 184.1061 Lactic acid. (a) Lactic acid (C3H6O3, CAS Reg. Nos.: dl mixture, 598-82-3; l-isomer, 79-33-4; d-isomer, 10326-41-7), the chemical 2-hydroxypropanoic acid,...

  8. 21 CFR 184.1061 - Lactic acid.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Lactic acid. 184.1061 Section 184.1061 Food and... Substances Affirmed as GRAS § 184.1061 Lactic acid. (a) Lactic acid (C3H6O3, CAS Reg. Nos.: dl mixture, 598-82-3; l-isomer, 79-33-4; d-isomer, 10326-41-7), the chemical 2-hydroxypropanoic acid,...

  9. Probing ground and low-lying excited states for HIO2 isomers

    NASA Astrophysics Data System (ADS)

    de Souza, Gabriel L. C.; Brown, Alex

    2014-12-01

    We present a computational study on HIO2 molecules. Ground state properties such as equilibrium structures, relative energetics, vibrational frequencies, and infrared intensities were obtained for all the isomers at the coupled-cluster with single and double excitations as well as perturbative inclusion of triples (CCSD(T)) level of theory with the aug-cc-pVTZ-PP basis set and ECP-28-PP effective core potential for iodine and the aug-cc-pVTZ basis set for hydrogen and oxygen atoms. The HOIO structure is confirmed as the lowest energy isomer. The relative energies are shown to be HOIO < HOOI < HI(O)O. The HO(O)I isomer is only stable at the density functional theory (DFT) level of theory. The transition states determined show interconversion of the isomers is possible. In order to facilitate future experimental identification, vibrational frequencies are also determined for all corresponding deuterated species. Vertical excitation energies for the three lowest-lying singlet and triplet excited states were determined using the configuration interaction singles, time-dependent density functional theory (TD-DFT)/B3LYP, TD-DFT/G96PW91, and equation of motion-CCSD approaches with the LANL2DZ basis set plus effective core potential for iodine and the aug-cc-pVTZ basis set for hydrogen and oxygen atoms. It is shown that HOIO and HOOI isomers have excited states accessible at solar wavelengths (<4.0 eV) but these states have very small oscillator strengths (<2 × 10-3).

  10. Probing ground and low-lying excited states for HIO2 isomers.

    PubMed

    de Souza, Gabriel L C; Brown, Alex

    2014-12-21

    We present a computational study on HIO2 molecules. Ground state properties such as equilibrium structures, relative energetics, vibrational frequencies, and infrared intensities were obtained for all the isomers at the coupled-cluster with single and double excitations as well as perturbative inclusion of triples (CCSD(T)) level of theory with the aug-cc-pVTZ-PP basis set and ECP-28-PP effective core potential for iodine and the aug-cc-pVTZ basis set for hydrogen and oxygen atoms. The HOIO structure is confirmed as the lowest energy isomer. The relative energies are shown to be HOIO < HOOI < HI(O)O. The HO(O)I isomer is only stable at the density functional theory (DFT) level of theory. The transition states determined show interconversion of the isomers is possible. In order to facilitate future experimental identification, vibrational frequencies are also determined for all corresponding deuterated species. Vertical excitation energies for the three lowest-lying singlet and triplet excited states were determined using the configuration interaction singles, time-dependent density functional theory (TD-DFT)/B3LYP, TD-DFT/G96PW91, and equation of motion-CCSD approaches with the LANL2DZ basis set plus effective core potential for iodine and the aug-cc-pVTZ basis set for hydrogen and oxygen atoms. It is shown that HOIO and HOOI isomers have excited states accessible at solar wavelengths (<4.0 eV) but these states have very small oscillator strengths (<2 × 10(-3)). PMID:25527931

  11. Probing ground and low-lying excited states for HIO{sub 2} isomers

    SciTech Connect

    Souza, Gabriel L. C. de; Brown, Alex

    2014-12-21

    We present a computational study on HIO{sub 2} molecules. Ground state properties such as equilibrium structures, relative energetics, vibrational frequencies, and infrared intensities were obtained for all the isomers at the coupled-cluster with single and double excitations as well as perturbative inclusion of triples (CCSD(T)) level of theory with the aug-cc-pVTZ-PP basis set and ECP-28-PP effective core potential for iodine and the aug-cc-pVTZ basis set for hydrogen and oxygen atoms. The HOIO structure is confirmed as the lowest energy isomer. The relative energies are shown to be HOIO < HOOI < HI(O)O. The HO(O)I isomer is only stable at the density functional theory (DFT) level of theory. The transition states determined show interconversion of the isomers is possible. In order to facilitate future experimental identification, vibrational frequencies are also determined for all corresponding deuterated species. Vertical excitation energies for the three lowest-lying singlet and triplet excited states were determined using the configuration interaction singles, time-dependent density functional theory (TD-DFT)/B3LYP, TD-DFT/G96PW91, and equation of motion-CCSD approaches with the LANL2DZ basis set plus effective core potential for iodine and the aug-cc-pVTZ basis set for hydrogen and oxygen atoms. It is shown that HOIO and HOOI isomers have excited states accessible at solar wavelengths (<4.0 eV) but these states have very small oscillator strengths (<2 × 10{sup −3})

  12. Cyanomethanimine Isomers in Cold Interstellar Clouds: Insights from Electronic Structure and Kinetic Calculations

    NASA Astrophysics Data System (ADS)

    Vazart, Fanny; Latouche, Camille; Skouteris, Dimitrios; Balucani, Nadia; Barone, Vincenzo

    2015-09-01

    New insights into the formation of interstellar cyanomethanimine, a species of great relevance in prebiotic chemistry, are provided by electronic structure and kinetic calculations for the reaction CN + CH2 = NH. This reaction is a facile formation route of Z,E-C-cyanomethanimine, even under the extreme conditions of density and temperature typical of cold interstellar clouds. E-C-cyanomethanimine has been recently identified in Sgr B2(N) in the Green Bank Telescope (GBT) PRIMOS survey by P. Zaleski et al. and no efficient formation routes have been envisaged so far. The rate coefficient expression for the reaction channel leading to the observed isomer E-C-cyanomethanimine is 3.15 × 10-10 × (T/300)0.152 × e(-0.0948/T). According to the present study, the more stable Z-C-cyanomethanimine isomer is formed with a slightly larger yield (4.59 × 10-10 × (T/300)0.153 × e(-0.0871/T). As the detection of E-isomer is favored due to its larger dipole moment, the missing detection of the Z-isomer can be due to the sensitivity limit of the GBT PRIMOS survey and the detection of the Z-isomer should be attempted with more sensitive instrumentation. The CN + CH2 = NH reaction can also play a role in the chemistry of the upper atmosphere of Titan where the cyanomethanimine products can contribute to the buildup of the observed nitrogen-rich organic aerosols that cover the moon.

  13. Acute Generalized Exanthematous Pustulosis Induced by Amoxicillin/Clavulanic Acid: Report of a Case Presenting With Generalized Lymphadenopathy.

    PubMed

    Syrigou, Ekaterini; Grapsa, Dimitra; Charpidou, Andriani; Syrigos, Konstantinos

    2015-01-01

    Drug-induced acute generalized exanthematous pustulosis is a rare pustular skin reaction, most commonly triggered by antibiotics. Although its diagnosis is based primarily on the presence of specific clinical and histopathologic features, additional in vivo (patch testing) or in vitro testing may be required, especially in atypical cases, to more accurately determine the causative agent. The authors report a histologically confirmed case of acute generalized exanthematous pustulosis that was induced by amoxicillin/clavulanic acid, as documented by subsequent patch testing, and presented with generalized painful lymphadenopathy, mimicking an acute infectious process. This is a very rare and diagnostically challenging clinical presentation of acute generalized exanthematous pustulosis, which has been reported, to the best of our knowledge, only once previously. PMID:25997755

  14. Differential adsorption of complex organic molecules isomers at interstellar ice surfaces

    NASA Astrophysics Data System (ADS)

    Lattelais, M.; Bertin, M.; Mokrane, H.; Romanzin, C.; Michaut, X.; Jeseck, P.; Fillion, J.-H.; Chaabouni, H.; Congiu, E.; Dulieu, F.; Baouche, S.; Lemaire, J.-L.; Pauzat, , F.; Pilmé, J.; Minot, C.; Ellinger, Y.

    2011-08-01

    Context. Over 20 of the ~150 different species detected in the interstellar and circumstellar media have also been identified in icy environments. For most of the species observed so far in the interstellar medium (ISM), the most abundant isomer of a given generic chemical formula is the most stable one (minimum energy principle - MEP) with few exceptions such as, for example, CH3COOH/HCOOCH3 and CH3CH2OH/CH3OCH3, whose formation is thought to occur on the icy mantles of interstellar grains. Aims: We investigate whether differences found in the compositions of molecular ices and the surrounding gas phase could originate from differences between the adsorption of one isomer from that of another at the ice surface. Methods: We performed a coherent and concerted theoretical/experimental study of the adsorption energies of the four molecules mentioned above, i.e. acetic acid (AA)/methyl formate (MF) and ethanol (EtOH)/dimethyl ether (DME) on the surface of water ice at low temperature. The question was first addressed theoretically at LCT using solid state periodic density functional theory (DFT) to represent the organized solid support. The experimental determination of the ice/molecule interaction energies was then carried out independently by two teams at LPMAA and LERMA/LAMAp using temperature programmed desorption (TPD) under an ultra-high vacuum (UHV) between 70 and 160 K. Results: For each pair of isomers, theory and experiments both agree that the most stable isomer (AA or EtOH) interacts more efficiently with the water ice than the higher energy isomer (MF or DME). This differential adsorption can be clearly seen in the different desorption temperatures of the isomers. It is not related to their intrinsic stability but instead to both AA and EtOH producing more and stronger hydrogen bonds with the ice surface. Conclusions: We show that hydrogen bonding may play an important role in the release of organic species from grains and propose that, depending on the

  15. Biocatalysis of linoleic acid to conjugated linoleic acid.

    PubMed

    Irmak, Sibel; Dunford, Nurhan Turgut; Gilliland, Stanley E; Banskalieva, Veneta; Eisenmenger, Michael

    2006-08-01

    CLA refers to a group of geometrical and positional isomers of linoleic acid (LA) with conjugated double bonds. CLA has been reported to have diverse health benefits and biological properties. Traditional organic synthesis is highly capital-intensive and results in an isomeric mixture of CLA isomers. Biotechnology presents new alternatives to traditional lipid manufacturing methods. The objective of this study was to examine the effect of protein isolation procedures on linoleate isomerase (LAI) recovery from microbial cells and biocatalysis of LA to CLA. Protein isolation experiments were carried out using Lactobacillus acidophilus L1 and two strains of Lactobacillus reuteri (ATCC 23272 and ATCC 55739). Under the same assay conditions, ATCC 55739 had the highest LAI activity among the microbial cultures examined in this study. Efficiency of cell lysis methods, which included various combinations of lysozyme and mutanolysin treatments in combination with sonication and osmotic rupture of cells with liquid nitrogen, was very low. Although treatment of cell material with a detergent (octylthioglucoyranoside) freed a significant amount of LAI activity into the solution, it was not sufficient to recover all the LAI activity from the residual cells. Crude LAI preparations produced mainly the cis-9,trans-11 CLA isomer. Time and substrate/protein ratio had a significant effect on biocatalysis of LA to CLA. It appears that the mechanism and kinetics of enzymatic conversion of LA to CLA are quite complex and requires further research using pure LAI preparations. PMID:17120931

  16. Isomer spectroscopy of {sup 127}Cd

    SciTech Connect

    Naqvi, F.; Gorska, M.; Grawe, H.; Beck, T.; Doornenbal, P.; Geissel, H.; Gerl, J.; Kojouharov, I.; Kurz, N.; Montes, F.; Prokopowicz, W.; Schaffner, H.; Tashenov, S.; Wollersheim, H. J.; Caceres, L.; Jungclaus, A.; Pfuetzner, M.; Werner-Malento, E.; Nowacki, F.; Sieja, K.

    2010-09-15

    The spin and configurational structure of excited states of {sup 127}Cd, the two-proton and three-neutron hole neighbor of {sup 132}Sn, has been studied. An isomeric state with a half-life of 17.5(3) {mu}s was populated in the fragmentation of a {sup 136}Xe beam on a {sup 9}Be target at a beam energy of 750 MeV/u. Time distributions of the delayed {gamma} transitions and {gamma}{gamma} coincidence relations were exploited to construct a decay scheme. The observed yrast (19/2){sup +} isomer is proposed to have dominant configurations of {nu}(h{sub 11/2}{sup -3}){pi}(g{sub 9/2}{sup -1},p{sub 1/2}{sup -1}), {nu}(h{sub 11/2}{sup -2}d{sub 3/2}{sup -1}){pi}(g{sub 9/2}{sup -2}), and {nu}(h{sub 11/2}{sup -2},s{sub 1/2}{sup -1}){pi}(g{sub 9/2}{sup -2}) and to decay by two competing stretched M2 and E3 transitions. Experimental results are compared with the isotone {sup 129}Sn. The new information provides input for the proton-neutron interaction and the evolution of neutron hole energies in nuclei around the doubly magic {sup 132}Sn core.

  17. Diastereomeric Ellagitannin Isomers from Penthorum chinense.

    PubMed

    Era, Manami; Matsuo, Yosuke; Shii, Takuya; Saito, Yoshinori; Tanaka, Takashi; Jiang, Zhi-Hong

    2015-08-28

    From the dried stem of Penthorum chinense (Penthoraceae), 1-O-galloyl-4,6-(R)-hexahydroxydiphenoyl (HHDP)-β-D-glucose and 2',4',6'-trihydroxyacetophenone 4'-O-[4,6-(R)-HHDP]-β-D-glucoside were isolated together with their (S)-HHDP isomers. Ellagitannins with a 4,6-(S)-HHDP-glucose moiety are widely distributed in the plant kingdom; however, 4,6-(R)-HHDP glucoses are extremely rare. Lowest-energy conformers of 1-O-galloyl-(S)- and (R)-HHDP-glucopyranoses were derived by density functional theory calculations, and the calculated (1)H and (13)C NMR chemical shifts and the (1)H-(1)H coupling constants were in agreement with the experimental values. The results revealed a conformational difference of the diastereomeric macrocyclic ester rings. In addition, a new compound, 1',3',5'-trihydroxybenzene 1'-O-[4,6-(S)-HHDP]-β-D-glucoside, was also isolated. PMID:26218585

  18. 227 Views of RNA: Is RNA Unique in Its Chemical Isomer Space?

    PubMed

    Cleaves, H James; Meringer, Markus; Goodwin, Jay

    2015-07-01

    Ribonucleic acid (RNA) is one of the two nucleic acids used by extant biochemistry and plays a central role as the intermediary carrier of genetic information in transcription and translation. If RNA was involved in the origin of life, it should have a facile prebiotic synthesis. A wide variety of such syntheses have been explored. However, to date no one-pot reaction has been shown capable of yielding RNA monomers from likely prebiotically abundant starting materials, though this does not rule out the possibility that simpler, more easily prebiotically accessible nucleic acids may have preceded RNA. Given structural constraints, such as the ability to form complementary base pairs and a linear covalent polymer, a variety of structural isomers of RNA could potentially function as genetic platforms. By using structure-generation software, all the potential structural isomers of the ribosides (BC5H9O4, where B is nucleobase), as well as a set of simpler minimal analogues derived from them, that can potentially serve as monomeric building blocks of nucleic acid-like molecules are enumerated. Molecules are selected based on their likely stability under biochemically relevant conditions (e.g., moderate pH and temperature) and the presence of at least two functional groups allowing the monomers to be incorporated into linear polymers. The resulting structures are then evaluated by using molecular descriptors typically applied in quantitative structure-property relationship (QSPR) studies and predicted physicochemical properties. Several databases have been queried to determine whether any of the computed isomers had been synthesized previously. Very few of the molecules that emerge from this structure set have been previously described. We conclude that ribonucleosides may have competed with a multitude of alternative structures whose potential proto-biochemical roles and abiotic syntheses remain to be explored. PMID:26200431

  19. Levofloxacin, an optical isomer of ofloxacin, has attenuated epileptogenic activity in mice and inhibitory potency in GABA receptor binding.

    PubMed

    Akahane, K; Tsutomi, Y; Kimura, Y; Kitano, Y

    1994-01-01

    The combination of some new quinolone antibacterials with 4-biphenylacetic acid (BPAA) functionally inhibits the gamma-amino-butyric acid (GABA) receptors and thereby induces clonic convulsions. We examined the effects of ofloxacin and its optical isomers on this quinolone-induced neurotoxicity. Norfloxacin at 10(-5) M alone or at 10(-7) M in combination with BPAA (10(-4) M) inhibited [3H]muscimol binding to rat brain synaptic membranes. Ofloxacin and its optical isomers did not affect muscimol binding by themselves. While they slightly reduced muscimol binding at 10(-4) M in combination with BPAA, the inhibitory activity of the l-isomer levofloxacin (DR-3355) on muscimol binding was slightly, but significantly, weaker than that of the d-isomer DR-3354 and ofloxacin. Intracisternal injection of norfloxacin (5 micrograms), ofloxacin, levofloxacin or DR-3354 (50 micrograms each) induced clonic convulsions in mice. The incidence of these convulsions was enhanced by the combination with BPAA (50 micrograms). The epileptogenic activity of levofloxacin was also weaker than that of DR-3354 or ofloxacin when quinolones were given alone or in combination with BPAA. These results suggest that epileptogenic activity of quinolones is closely related to the inhibitory potency in GABA receptor binding and that levofloxacin may have lower neurotoxicity than ofloxacin and DR-3354. PMID:7842825

  20. Crystal Structure of the 11-cis Isomer of Pharaonis Halorhodopsin: Structural Constraints on Interconversions among Different Isomeric States.

    PubMed

    Chan, Siu Kit; Kawaguchi, Haruki; Kubo, Hiroki; Murakami, Midori; Ihara, Kunio; Maki, Kosuke; Kouyama, Tsutomu

    2016-07-26

    Like other microbial rhodopsins, the light driven chloride pump halorhodopsin from Natronomonas pharaonis (pHR) contains a mixture of all-trans/15-anti and 13-cis/15-syn isomers in the dark adapted state. A recent crystallographic study of the reaction states of pHR has shown that reaction states with 13-cis/15-syn retinal occur in the anion pumping cycle that is initiated by excitation of the all-trans isomer. In this study, we investigated interconversions among different isomeric states of pHR in the absence of chloride ions. The illumination of chloride free pHR with red light caused a large blue shift in the absorption maximum of the retinal visible band. During this "red adaptation", the content of the 11-cis isomer increased significantly, while the molar ratio of the 13-cis isomer to the all-trans isomer remained unchanged. The results suggest that the thermally activated interconversion between the 13-cis and the all-trans isomers is very rapid. Diffraction data from red adapted crystals showed that accommodation of the retinal chromophore with the 11-cis/15-syn configuration was achieved without a large change in the retinal binding pocket. The measurement of absorption kinetics under illumination showed that the 11-cis isomer, with a λmax at 565 nm, was generated upon excitation of a red-shifted species (λmax = 625 nm) that was present as a minor component in the dark adapted state. It is possible that this red-shifted species mimics an O-like reaction state with 13-cis/15-syn retinal, which was hypothesized to occur at a late stage of the anion pumping cycle. PMID:27352034

  1. Simple Nuclear Structure in Cd-129111 from Atomic Isomer Shifts

    NASA Astrophysics Data System (ADS)

    Yordanov, D. T.; Balabanski, D. L.; Bissell, M. L.; Blaum, K.; Budinčević, I.; Cheal, B.; Flanagan, K.; Frömmgen, N.; Georgiev, G.; Geppert, Ch.; Hammen, M.; Kowalska, M.; Kreim, K.; Krieger, A.; Meng, J.; Neugart, R.; Neyens, G.; Nörtershäuser, W.; Rajabali, M. M.; Papuga, J.; Schmidt, S.; Zhao, P. W.

    2016-01-01

    Isomer shifts have been determined in 111-129>Cd by high-resolution laser spectroscopy at CERN-ISOLDE. The corresponding mean square charge-radii changes, from the 1 /2+ and the 3 /2+ ground states to the 11 /2- isomers, have been found to follow a distinct parabolic dependence as a function of the atomic mass number. Since the isomers have been previously associated with simplicity due to the linear mass dependence of their quadrupole moments, the regularity of the isomer shifts suggests a higher order of symmetry affecting the ground states in addition. A comprehensive description assuming nuclear deformation is found to accurately reproduce the radii differences in conjunction with the known quadrupole moments. This intuitive interpretation is supported by covariant density functional theory.

  2. Molecular structure of uranium carbides: Isomers of UC3

    NASA Astrophysics Data System (ADS)

    Zalazar, M. Fernanda; Rayón, Víctor M.; Largo, Antonio

    2013-03-01

    In this article, the most relevant isomers of uranium tricarbide are studied through quantum chemical methods. It is found that the most stable isomer has a fan geometry in which the uranium atom is bonded to a quasilinear C3 unit. Both, a rhombic and a ring CU(C2) structures are found about 104-125 kJ/mol higher in energy. Other possible isomers including linear geometries are located even higher. For each structure, we provide predictions for those molecular properties (vibrational frequencies, IR intensities, dipole moments) that could eventually help in their experimental detection. We also discuss the possible routes for the formation of the different UC3 isomers as well as the bonding situation by means of a topological analysis of the electron density.

  3. ORAL TOXICOLOGY STUDIES WITH XYLENE ISOMERS AND MIXED XYLENES

    EPA Science Inventory

    Xylene isomers and mixed xylenes were administered to male and female Sprague-Dawley rats to evaluate their effects on standard toxicological parameters rnhich included body and organ weights, hematology, serum chemistries, urinalysis and histopathological examination. n the init...

  4. Molecular structure of uranium carbides: isomers of UC3.

    PubMed

    Zalazar, M Fernanda; Rayón, Víctor M; Largo, Antonio

    2013-03-21

    In this article, the most relevant isomers of uranium tricarbide are studied through quantum chemical methods. It is found that the most stable isomer has a fan geometry in which the uranium atom is bonded to a quasilinear C3 unit. Both, a rhombic and a ring CU(C2) structures are found about 104-125 kJ/mol higher in energy. Other possible isomers including linear geometries are located even higher. For each structure, we provide predictions for those molecular properties (vibrational frequencies, IR intensities, dipole moments) that could eventually help in their experimental detection. We also discuss the possible routes for the formation of the different UC3 isomers as well as the bonding situation by means of a topological analysis of the electron density. PMID:23534639

  5. Enhanced Raman spectroscopic study of rotational isomers on metal surfaces

    NASA Technical Reports Server (NTRS)

    Loo, B. H.; Lee, Y. G.; Frazier, D. O.

    1986-01-01

    Surfaced-enhanced Raman spectroscopy has been used to study rotational isomers of succinonitrile and N-methyl-thioacetamide on Cu and Ag surfaces. Both the gauche and trans conformers of succinonitrile are found to chemisorb on the metal surface. The doubly degenerate nu(C-triple bond-N) in the free molecules is removed when succinonitrile adsorbs on copper, which indicates that the two (C-triple bond-N) groups are no longer chemically equivalent. Both conformers are found to coordinate to the copper surface through the pi system of one of the two (C-triple bond-N) groups. In the case of N-methyl-thioacetamide, the population of the cis isomer is greatly increased on Cu and Ag surfaces. This is probably due to surface-induced cis-trans isomerization, in which the predominant trans isomer is converted to the cis isomer.

  6. Measurements of single nucleotide electronic states as nanoelectronic fingerprints for identification of DNA nucleobases, their protonated and unprotonated states, isomers, and tautomers.

    PubMed

    Ribot, Josep Casamada; Chatterjee, Anushree; Nagpal, Prashant

    2015-04-16

    Several nanoelectronic techniques have been explored to distinguish the sequence of nucleic acids in DNA macromolecules. Identification of unique electronic signatures using nanopore conductance, tunneling spectroscopy, or other nanoelectronic techniques depends on electronic states of the DNA nucleotides. While several experimental and computational studies have focused on interaction of nucleobases with different substrates, the effect of nucleic acid biochemistry on its electronic properties has been largely unexplored. Here, we present correlated measurements of frontier molecular orbitals and higher-order electronic states for four DNA nucleobases (adenine, cytosine, thymine, and guanine), and first-principle quantum chemical density functional theoretical (DFT) computations. Using different pH conditions in our experiments, we show that small changes in the biochemical state of these nucleic acids strongly affect the intrinsic electronic structure, measured using scanning tunneling spectroscopy (STS). In our experimental measurements and computations, significant differences were observed between the position of frontier orbitals and higher-energy states between protonated and unprotonated nucleic acids, isomers, and different keto-enol tautomer's formed in these nucleotides, leading to their facile identification. Furthermore, we show unique "electronic fingerprints" for all nucleotides (A, G, T, C) using STS, with most distinct states identified at acidic pH. These results can have important implications for identification of nucleic acid sequences in DNA molecules using a high-throughput nanoelectronic identification technique. PMID:25793310

  7. Synthesis of dibenzylamino-1-methylcyclohexanol and dibenzylamino-1-trifluoromethylcyclohexanol isomers.

    PubMed

    Jones, D Heulyn; Bresciani, Stefano; Tellam, James P; Wojno, Justyna; Cooper, Anthony W J; Kennedy, Alan R; Tomkinson, Nicholas C O

    2016-01-01

    The isomers of dibenzylamino-1-methylcyclohexan-1-ol and dibenzylamino-1-trifluoromethylcyclohexan-1-ol have been prepared. The stereochemistry of these compounds was unequivocally assigned through a combination of NMR spectroscopy and single crystal X-ray analysis. The cis-isomer of 3-N,N-dibenzylamino-1-trifluoromethylcyclohexanol and its derivatives display an unusual conformational behaviour in both solution-phase and the solid-state, where the amino group usually adopts an axial conformation. PMID:26468867

  8. Differential Degradation of Nonylphenol Isomers by Sphingomonas xenophaga Bayram

    PubMed Central

    Gabriel, Frédéric L. P.; Giger, Walter; Guenther, Klaus; Kohler, Hans-Peter E.

    2005-01-01

    Sphingomonas xenophaga Bayram, isolated from the activated sludge of a municipal wastewater treatment plant, was able to utilize 4-(1-ethyl-1,4-dimethylpentyl)phenol, one of the main isomers of technical nonylphenol mixtures, as a sole carbon and energy source. The isolate degraded 1 mg of 4-(1-ethyl-1,4-dimethylpentyl)phenol/ml in minimal medium within 1 week. Growth experiments with five nonylphenol isomers showed that the three isomers with quaternary benzylic carbon atoms [(1,1,2,4-tetramethylpentyl)phenol, 4-(1-ethyl-1,4-dimethylpentyl)phenol, and 4-(1,1-dimethylheptyl)phenol] served as growth substrates, whereas the isomers containing one or two hydrogen atoms in the benzylic position [4-(1-methyloctyl)phenol and 4-n-nonylphenol] did not. However, when the isomers were incubated as a mixture, all were degraded to a certain degree. Differential degradation was clearly evident, as isomers with more highly branched alkyl side chains were degraded much faster than the others. Furthermore, the C9 alcohols 2,3,5-trimethylhexan-2-ol, 3,6-dimethylheptan-3-ol, and 2-methyloctan-2-ol, derived from the three nonylphenol isomers with quaternary benzylic carbon atoms, were detected in the culture fluid by gas chromatography-mass spectrometry, but no analogous metabolites could be found originating from 4-(1-methyloctyl)phenol and 4-n-nonylphenol. We propose that 4-(1-methyloctyl)phenol and 4-n-nonylphenol were cometabolically transformed in the growth experiments with the mixture but that, unlike the other isomers, they did not participate in the reactions leading to the detachment of the alkyl moiety. This hypothesis was corroborated by the observed accumulation in the culture fluid of an as yet unidentified metabolite derived from 4-(1-methyloctyl)phenol. PMID:15746308

  9. Existence of Exotic Torus Isomer States and Their Precession Motions

    NASA Astrophysics Data System (ADS)

    Ichikawa, Takatoshi; Matsuyanagi, Kenichi; Maruhn, Joachim A.; Itagaki, Naoyuki

    We systematically investigate the existence of exotic high-spin torus isomers and their precession motions for a series of N = Z even-even nuclei from 28Si to 56Ni. For this purpose, we use the cranked three-dimensional Hatree-Fock (HF) method in a systematic search for high-spin torus isomers and the three-dimensional time-dependent Hatree-Fock (TDHF) method for describing the precession motion of the torus isomer. We obtain high-spin torus isomers in 36Ar, 40Ca, 44Ti, 48Cr, and 52Fe. The emergence of the torus isomers is associated with the alignments of single-particle angular momenta, which is the same mechanism as found in 40Ca. We find that all the obtained torus isomers execute the precession motion at least two rotational periods. The moment of inertia about a perpendicular axis, which characterizes the precession motion, is found to be close to the classical rigid-body value.

  10. Frequency Patterns of T-Cell Exposed Amino Acid Motifs in Immunoglobulin Heavy Chain Peptides Presented by MHCs.

    PubMed

    Bremel, Robert D; Homan, E Jane

    2014-01-01

    Immunoglobulins are highly diverse protein sequences that are processed and presented to T-cells by B-cells and other antigen presenting cells. We examined a large dataset of immunoglobulin heavy chain variable regions (IGHV) to assess the diversity of T-cell exposed motifs (TCEMs). TCEM comprise those amino acids in a MHC-bound peptide, which face outwards, surrounded by the MHC histotope, and which engage the T-cell receptor. Within IGHV there is a distinct pattern of predicted MHC class II binding and a very high frequency of re-use of the TCEMs. The re-use frequency indicates that only a limited number of different cognate T-cells are required to engage many different clonal B-cells. The amino acids in each outward-facing TCEM are intercalated with the amino acids of inward-facing MHC groove-exposed motifs (GEM). Different GEM may have differing, allele-specific, MHC binding affinities. The intercalation of TCEM and GEM in a peptide allows for a vast combinatorial repertoire of epitopes, each eliciting a different response. Outcome of T-cell receptor binding is determined by overall signal strength, which is a function of the number of responding T-cells and the duration of engagement. Hence, the frequency of TCEM re-use appears to be an important determinant of whether a T-cell response is stimulatory or suppressive. The frequency distribution of TCEMs implies that somatic hypermutation is followed by T-cell clonal expansion that develops along repeated pathways. The observations of TCEM and GEM derived from immunoglobulins suggest a relatively simple, yet powerful, mechanism to correlate T-cell polyspecificity, through re-use of TCEMs, with a very high degree of specificity achieved by combination with a diversity of GEMs. The frequency profile of TCEMs also points to an economical mechanism for maintaining T-cell memory, recall, and self-discrimination based on an endogenously generated profile of motifs. PMID:25389426

  11. 241Am (n,gamma) isomer ratio measurement

    SciTech Connect

    Bond, Evelyn M; Vieira, David J; Moody, Walter A; Slemmons, Alice K

    2011-01-05

    The objective of this project is to improve the accuracy of the {sup 242}Cm/{sup 241}Am radiochemistry ratio. We have performed an activation experiment to measure the {sup 241}Am(n,{gamma}) cross section leading to either the ground state of {sup 242g}Am (t{sub 1/2} = 16 hr) which decays to {sup 242}Cm (t{sub 1/2} = 163 d) or the long-lived isomer {sup 242m}Am (t{sub 1/2} = 141 yr). This experiment will develop a new set of americium cross section evaluations that can be used with a measured {sup 242}Cm/{sup 241}Am radiochemical measurement for nuclear forensic purposes. This measurement is necessary to interpret the {sup 242}Cm/{sup 241}Am ratio because a good measurement of this neutron capture isomer ratio for {sup 241}Am does not exist. The targets were prepared in 2007 from {sup 241}Am purified from LANL stocks. Gold was added to the purified {sup 241}Am as an internal neutron fluence monitor. These targets were placed into a holder, packaged, and shipped to Forschungszentrum Karlsruhe, where they were irradiated at their Van de Graff facility in February 2008. One target was irradiated with {approx}25 keV quasimonoenergetic neutrons produced by the {sup 7}Li(p,n) reaction for 3 days and a second target was also irradiated for 3 days with {approx}500 keV neutrons. Because it will be necessary to separate the {sup 242}Cm from the {sup 241}Am in order to measure the amount of {sup 242}Cm by alpha spectrometry, research into methods for americium/curium separations were conducted concurrently. We found that anion exchange chromatography in methanol/nitric acid solutions produced good separations that could be completed in one day resulting in a sample with no residue. The samples were returned from Germany in July 2009 and were counted by gamma spectrometry. Chemical separations have commenced on the blank sample. Each sample will be spiked with {sup 244}Cm, dissolved and digested in nitric acid solutions. One third of each sample will be processed at a time

  12. 227 Views of RNA: Is RNA Unique in Its Chemical Isomer Space?

    PubMed Central

    Meringer, Markus; Goodwin, Jay

    2015-01-01

    Abstract Ribonucleic acid (RNA) is one of the two nucleic acids used by extant biochemistry and plays a central role as the intermediary carrier of genetic information in transcription and translation. If RNA was involved in the origin of life, it should have a facile prebiotic synthesis. A wide variety of such syntheses have been explored. However, to date no one-pot reaction has been shown capable of yielding RNA monomers from likely prebiotically abundant starting materials, though this does not rule out the possibility that simpler, more easily prebiotically accessible nucleic acids may have preceded RNA. Given structural constraints, such as the ability to form complementary base pairs and a linear covalent polymer, a variety of structural isomers of RNA could potentially function as genetic platforms. By using structure-generation software, all the potential structural isomers of the ribosides (BC5H9O4, where B is nucleobase), as well as a set of simpler minimal analogues derived from them, that can potentially serve as monomeric building blocks of nucleic acid–like molecules are enumerated. Molecules are selected based on their likely stability under biochemically relevant conditions (e.g., moderate pH and temperature) and the presence of at least two functional groups allowing the monomers to be incorporated into linear polymers. The resulting structures are then evaluated by using molecular descriptors typically applied in quantitative structure–property relationship (QSPR) studies and predicted physicochemical properties. Several databases have been queried to determine whether any of the computed isomers had been synthesized previously. Very few of the molecules that emerge from this structure set have been previously described. We conclude that ribonucleosides may have competed with a multitude of alternative structures whose potential proto-biochemical roles and abiotic syntheses remain to be explored. Key Words: Evolution—Chemical evolution

  13. Up- and down-regulation of beta-adrenoreceptors in rat cerebral cortex following exposure to isomers of hexachlorocyclohexane

    SciTech Connect

    Stark, L.; Hollinger, M.; Joy, R.

    1986-03-01

    The authors have shown that the gamma (lindane) and beta isomers of hexachlorocyclohexane (HCH) have opposite effects on the kindling model of epilepsy (gamma facilitates, beta retards kindling acquisition). In the present study the authors determined the effects of these two isomers on ..beta..-adrenoreceptors in rat brain using /sup 3/H-dihydroalprenolol as the ligand following 10 days treatment with 10 mg/kg p.o. of isomers or corn oil. Results showed a statistically significant decrease in the number of ..beta..-adrenoreceptors in cortical tissue taken from lindane treated rats. In contrast, there was a significant increase in the number of ..beta..-adreno receptors in cortical tissue taken from beta-HCH treated rats. Neither treatment caused a significant change in Kd. It is concluded that the ..beta..-adrenoreceptor system in rat brain is differentially affected by the isomers of HCH. Since the kindling model of epilepsy is sensitive to modulation in adrenergic function, this system may be involved in the pro- and anticonvulsant effects of these HCH isomers on kindling acquisition.

  14. Tautomeric conversion, vibrational spectra, and density functional studies on peripheral sulfur derivatives of benzothiazole and benzothiazoline isomers

    NASA Astrophysics Data System (ADS)

    Altun, Ahmet; Kuliyev, Eziz; Aghatabay, Naz M.

    2016-01-01

    The room temperature structural (tautomerism, dimerization, conformational preference, geometry parameters) and vibrational spectral (IR and Raman) analyses have been performed on benzothiazoline (benzothiazoline-2-thione, 3-methyl-benzothiazoline-2-thione) and benzothiazole [2-mercaptobenzothiazole, 2-methylthiobenzothiazole, and bis(benzothiazole-2-ylthio)ethane] derivatives at the B3LYP/6-311++G∗∗ level of theory. Although the keto to enol transition barriers are too high over the most stable benzothiazoline isomers, vibrational spectral analyses reveal some major bands of benzothiazole isomers in the present room temperature experimental FT-IR and FT-Raman specta. Therefore, benzothiazole isomers exist at rare amounts in the powdered samples that are mainly composed of benzothiazoline isomers. The benzothiazole isomers have two stable conformations due to the orientation of their SH and SCH3 moieties. The energetic and vibrational spectral analyses suggest that the benzothiazoline-2-thione molecules can be stabilized further through the NH⋯S intermolecular hydrogen bonds in solid phase. All observed fundamental vibrational bands of the molecules have been assigned based on the calculated mode frequencies and IR/Raman intensities. The mode assignments have been expressed in terms of internal coordinates and their percent potential energy distributions. The effects of substitution at the nitrogen and peripheral sulfur atoms have been analyzed for the geometries and vibrational bands of the molecules.

  15. Ion-neutral collisional cross sections of carbohydrate isomers as divalent cation adducts and their electron transfer products.

    PubMed

    Huang, Yuting; Dodds, Eric D

    2015-10-21

    As the gravity of glycoscience continues to amass, a commensurate demand for rapid, sensitive, and structurally comprehensive glycoanalytical tools has arisen. Among the most elusive but desirable analytical capabilities is the ability to expeditiously and unambiguously detect, distinguish, and resolve carbohydrates that differ only in their constitutional isomerism and/or stereoisomerism. While ion mobility spectrometry (IMS) has proven a highly promising tool for such analyses, the facility of this method to discriminate larger oligosaccharides is still somewhat limited. In an effort to expand the capabilities of IMS to discriminate among carbohydrate isomers, the present investigation was focused on IMS studies of four trisaccharide isomers, four pentasaccharide isomers, and two hexasaccharide isomers, each as group II metal ion adducts and their corresponding gas-phase electron transfer (ET) products. These studies were also evaluated in the context of previously investigated group I metal ion adducts of the same saccharides. The orientationally averaged ion-neutral collisional cross sections (CCSs) of the various carbohydrate/metal ion adducts were found to be dependent on the structures of specific carbohydrate isomers, sensitive to the electronic characteristics of the bound cation, and responsive to the attachment of an additional electron (in the case of divalent metal ion adducts). Overall, these results underscore the utility of metal ions for probing carbohydrate structure in concert with IMS, and the capacity of gas-phase ion chemistry to expand the menu of such probes. PMID:26225371

  16. The biosynthesis of cyanogenic glucosides in higher plants. The (E)- and (Z)-isomers of p-hydroxyphenylacetaldehyde oxime as intermediates in the biosynthesis of dhurrin in Sorghum bicolor (L. ) Moench

    SciTech Connect

    Halkier, B.A.; Olsen, C.E.; Moller, B.L. )

    1989-11-25

    The biosynthesis of the tyrosine-derived cyanogenic glucoside dhurrin has been studied with a microsomal preparation obtained from etiolated seedlings of sorghum. The biosynthetic pathway involves tyrosine, N-hydroxytyrosine, and p-hydroxyphenylacetaldehyde oxime as early intermediates. The use of deuterium-labeled tyrosine and mass spectrometric analyses demonstrate that the alpha-hydrogen atom of tyrosine is retained in the conversion of tyrosine to p-hydroxyphenylacetaldehyde oxime. This excludes p-hydroxyphenylpyruvic acid oxime as intermediate in the pathway. A high pressure liquid chromatography method was developed to separate the (E)- and (Z)-isomers of p-hydroxyphenylacetaldehyde oxime. The microsomal enzyme system was found to produce initially the (E)-isomer of p-hydroxyphenylacetaldehyde oxime. An isomerase then converts the (E)-isomer to the (Z)-isomer, which is the isomer preferentially utilized by the microsomal enzyme system in the subsequent biosynthetic reactions. The (E)-isomer produced in situ is more efficiently converted to the (Z)-isomer than exogenously added (E)-isomer and may thus be metabolically channeled.

  17. High-K isomers in {sup 176}W and mechanisms of K-violation

    SciTech Connect

    Crowell, B.; Janssens, R.V.F.; Blumenthal, D.J.

    1995-08-01

    K-isomers are states in deformed nuclei whose {gamma}-decay is hindered by selection rules involving K, the projection of the angular momentum along the axis of symmetry of the nucleus. Previous work with the Argonne Notre Dame BGO Array delineated the existence of two K-isomers in {sup 176}W, one of which had a very unusual pattern of decay. A short description of this work was published as a letter, and a more complete account is being readied for submission. These results provided evidence that quantum-mechanical fluctuations in the nuclear shape may be responsible for some of the observed K-violating transitions. In addition, hints were present in the data of the existence of another K-isomer with an even higher in. An experiment was performed in September 1994 to observe this isomer, using the reaction {sup 50}Ti({sup 130}Te,4n), and a technique in which recoiling {sup 176}W nuclei were created 17-cm upstream of the center of the array and caught on a Pb catcher foil at the center. Intense ({approximately} 3 pnA) beams of {sup 130}Te were supplied by the ECR source using a new sputtering technique. The recoil-shadow geometry was highly successful at removing the background from non-isomeric decays, allowing the weakly populated K-isomers to be detected cleanly. In addition, the availability of pulsed beams from ATLAS and the timing data from the BGO array provided a second technique for isolating the decays of interest, by selecting events in which a given number of BGO detectors fired between beam pulses. This method was used in the previous experiment, and was also applied in this experiment as a second level of selection. As a result, gamma-ray transitions were detected in the present experiment with intensities as small as {approximately} 0.02 % of the {sup 176}W reaction channel. The existence of the new isomer was confirmed, and a partial level-scheme was constructed.

  18. PARTICLE-HOLE NATURE OF THE LIGHT HIGH-SPIN TOROIDAL ISOMERS

    SciTech Connect

    Staszczak, A.; Wong, Cheuk-Yin

    2015-01-01

    Nuclei under non-collective rotation with a large angular momentum above some threshold can assume a toroidal shape. In our previous work, we showed by using cranked Skyrme Hartree Fock approach that even even, N = Z, high-K, toroidal isomeric states may have general occurrences for light nuclei with 28 < A < 52. We present here some additional results and systematics on the particle-hole nature of these high-spin toroidal isomers.

  19. Metal-Organic Framework Isomers with Diamondoid Networks Constructed of a Semi-Rigid Tetrahedral Linker

    SciTech Connect

    Tian, Jian; Motkuri, Radha K.; Thallapally, Praveen K.; McGrail, B. Peter

    2010-10-19

    Solvothermal assembly of a semi-rigid tetrahedral carboxylate ligand tetrakis[4-(carboxyphenyl)oxamethyl]methane acid (H4X) with Cd(II) ion in different solvent systems yields three novel metal-organic framework isomers (1-3) based on different secondary building units (SBUs). Although all three frameworks have the same dia (diamondoid) topology, complex 1 and 3 are chiral and complex 2 is achiral. One of the networks, 3 shows cross-linked three-fold interpenetration of the single dia net and exhibits permanent porosities, as confirmed by BET and selective CO2 adsorption.

  20. Quantitative analysis of positional isomers of triacylglycerols via electrospray ionization tandem mass spectrometry of sodiated adducts.

    PubMed

    Herrera, Lisandra Cubero; Potvin, Michael A; Melanson, Jeremy E

    2010-09-01

    Herein we report a reversed-phase high-performance liquid chromatography tandem mass spectrometry (RP-HPLC/MS/MS) method for the analysis of positional isomers of triacylglycerols (TAGs) in vegetable oils. The fragmentation behavior of [M + X](+) ions (X = NH(4), Li, Na or Ag) was studied on a quadrupole-time-of-flight (Q-TOF) mass spectrometer under low-energy collision-induced dissociation (CID) conditions. Mass spectra that were dependent on the X(+) ion and the nature and position of the acyl substituents were observed for four pairs of 'AAB/ABA'-type TAGs, namely PPO/POP, OOP/OPO, LLO/LOL and OOL/OLO (where P is 16:0, palmitic acid; O is 18:1, oleic acid; and L is 18:2, linoleic acid). For the majority of [M + X](+) adducts, the loss of the fatty acid in the outer positions (sn-1 or sn-3) was favored over the loss in the central position (sn-2), which enabled the determination of the fractional abundance of the isomers. Ratios of the intensity of fragment ions at various AAB/ABA compositions produced linear calibration curves with positive slopes, comparable to those obtained traditionally by ESI-MS/MS of [M + NH(4)](+) adducts. The only exceptions were the [M + Ag](+) adducts of the PPO/POP system, which produced calibration curves with negative slopes. Sodium adducts provided the most consistent level of isomeric discrimination for the TAGs studied and also offered the most convenience in that they required no additive to the mobile phase. Therefore, calibration curve data derived from [M + Na](+) adducts were applied to the quantification of TAG regioisomers in sunflower and olive oils. The regiospecific analysis showed that palmitic acid was typically located at positions sn-1 or sn-3, whereas unsaturated fatty acids, oleic and linoleic acids were mostly found at the sn-2 position. PMID:20814981

  1. Ab initio molecular orbital studies of low-energy, metastable isomers of the ubiquitous cyclopropenylidene. [in interstellar space

    NASA Technical Reports Server (NTRS)

    Defrees, D. J.; Mclean, A. D.

    1986-01-01

    The discovery of cyclopropenylidene in space suggests that other C3H2 isomers may be present, and a tentative detection of one such isomer, propargylene (HCCCH), has been reported. Ab initio molecular orbital theory has been used to characterize five low-lying, metastable isomers of cyclopropenylidene. Extended calculations including the electron correlation energy, show that the lowest in energy is singlet propadienylidene, followed by propargylene; the singlet and triplet of the latter are too close in energy to allow an assignment of the ground state; triplet propadienylidene is at a significantly higher energy. Rotational frequencies computed to an expected accuracy of + or - 1 -2 percent do not confirm the tentative detection of propargylene in space, although the discrepancy between theory and the observation is not so great as to unequivocally rule out this possibility.

  2. Computations of 36 tautomer/isomer equilibria of different lactams.

    PubMed

    Galstyan, Gegham; Knapp, Ernst-Walter

    2012-06-28

    Gas-phase energies of 36 tautomer/isomer pairs of 18 six-membered N-heterocyclic compounds were computed quantum chemically. Among the considered B3LYP, BH&HLYP, BH&HLYP(G), and PW6B95 DFT functionals, the latter two provide accurate tautomer/isomer pair energies with root-mean-square deviations (rmsd) relative to experiments of 0.2 and 0.3 kcal/mol, respectively. Since only few (namely five) experimental data are available, 15 tautomer/isomer pair energies were computed with the very precise QCISD(T)(quadruple-ζ) method serving as reference. Relative to this reference the PW6B95 DFT functional is slightly superior to the BH&HLYP(G) functional, yielding an rmsd of 0.7 and 0.8 kcal/mol, respectively. In contrast to BH&HLYP(G), the PW6B95 DFT functional yields also accurate tautomer/isomer pair energies if zwitterionic structures are involved. The tautomer/isomer pair states possess different amounts of aromaticity. This is characterized by nucleus-independent chemical shift (NICS) values. The tautomer/isomer pair reference energies, from which the energies computed with PW6B95 are subtracted, correlate linearly with the corresponding differences in the NICS values. This correlation is used to construct a correction term for the pair energies computed with PW6B95, yielding tautomer/isomer pair energies with rmsd of 0.3 kcal/mol with respect to the more CPU time demanding QCISD(T)(quadruple-ζ) method. PMID:22646903

  3. Mass spectrometry and decay spectroscopy of isomers across the Z=82 shell closure

    NASA Astrophysics Data System (ADS)

    Stanja, J.; Borgmann, Ch.; Agramunt, J.; Algora, A.; Beck, D.; Blaum, K.; Böhm, Ch.; Breitenfeldt, M.; Cocolios, T. E.; Fraile, L. M.; Herfurth, F.; Herlert, A.; Kowalska, M.; Kreim, S.; Lunney, D.; Manea, V.; Minaya Ramirez, E.; Naimi, S.; Neidherr, D.; Rosenbusch, M.; Schweikhard, L.; Simpson, G.; Wienholtz, F.; Wolf, R. N.; Zuber, K.

    2013-11-01

    Recent results from a measurement campaign studying the isomerism in neutron-deficient Tl isotopes are presented. The measurements make use of a nuclear spectroscopy setup coupled to the high-resolution Penning-trap mass spectrometer ISOLTRAP at CERN's radioactive ion-beam facility ISOLDE. The mass values of 190,194Tl are improved and a mass-spin-state assignment is carried out. An additional mass measurement of the grandparent nuclide 198At allows the deduction of the spin-state ordering in 190Tl. As a result, the excitation energies of the isomers in both Tl isotopes are determined for the first time to Eex(194Tl)=260(15) keV and Eex(190Tl)=89(12) keV. Furthermore, this allows anchoring of the ground-state and isomer masses of 194Bi, 202Fr, and 206Ac, which are linked by two independent α-decay chains.

  4. Identification of an {alpha}-decaying (9{sup -}) isomer in {sup 216}Fr

    SciTech Connect

    Kurcewicz, J.; Karny, M.; Korgul, A.; Kurcewicz, W.; Kurpeta, J.; Lewandowski, S.; Majorkiewicz, P.; Plochocki, A.; Wojtasiewicz, A.; Czarnacki, W.; Kasztelan, M.; Kisielinski, M.; Penttilae, H.; Roussiere, B.; Steczkiewicz, O.

    2007-11-15

    The {alpha} decay of the trans-lead isotopes {sup 212}At, {sup 216}Fr, and {sup 220}Ac was investigated by using mass-separated sources and analog as well as digital signal processing. By measuring {alpha}-{alpha} time correlations evidence was obtained for the occurrence of an {alpha}-decaying (9{sup -}) isomer in {sup 216}Fr. The {alpha}-decay energy and half-life amount to 9000(5) keV and 850(30) ns, respectively. The excitation energy of the isomer is compared with shell-model predictions for the high-spin members of the {pi}(h{sub 9/2}){nu}(g{sub 9/2}) multiplet, and the relevance of the new data concerning the search for reflection asymmetry is presented.

  5. High-K isomers in transactinide nuclei close to N = 162

    SciTech Connect

    Prassa, V. Nikšić, T.; Vretenar, D.; Lu, Bing-Nan; Ackermann, D.

    2015-10-15

    Transactinide nuclei around neutron number N = 162 display axially deformed equilibrium shapes, as shown in our previous analysis [1] of constrained mean-field energy surfaces and collective excitation spectra. In the present study we are particularly interested in the occurrence of high-K isomers in the axially deformed isotopes of Rf (Z = 104), Sg (Z = 106), Hs (Z = 108), and Ds (Z = 110), with neutron number N = 160 − 166 and the effect of the N=162 closure on the structure and distribution of two-quasiparticle (2qp) states. The evolution of high-K isomers is analysed in a self-consistent axially-symmetric relativistic Hartree-Bogoliubov calculation using the blocking approximation with time-reversal symmetry breaking.

  6. A maize death acid, 10-oxo-11-phytoenoic acid, is the predominant cyclopentenone signal present during multiple stress and developmental conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Recently we investigated the function of the 9-lipoxygenase (LOX) derived cyclopentenones 10-oxo-11-phytoenoic acid (10-OPEA) and 10-oxo-11-phytodienoic acid (10-OPDA) and identified their C-14 and C-12 derivatives. 10-OPEA accumulation is elicited by fungal and insect attack and acts as a strong in...

  7. Unstable Isomer of C90 Fullerene Isolated as Chloro Derivatives, C90 (1)Cl10/12.

    PubMed

    Chilingarov, Norbert S; Troyanov, Sergey I

    2016-07-01

    High-temperature chlorination of C90 -containing fullerene fraction resulted in the isolation and X-ray structural characterization of C90 (1)Cl10/12 , the first derivatives of a relatively unstable isomer D5h -C90 (1) with a nanotubular shape. In the crystal structure, three isomers of both C90 (1)Cl10 and C90 (1)Cl12 with similar chlorination patterns co-crystallize in the same crystallographic site. Thus, in contrast to the previous reports, D5h -C90 (1) is present, though with a low abundance, in the fullerene soot produced by arc-discharge method with undoped graphite rods. PMID:27311795

  8. Incorporation mechanisms of a branched nonylphenol isomer in soil-derived organo-clay complexes during a 180-day experiment.

    PubMed

    Riefer, Patrick; Klausmeyer, Timm; Adams, Alina; Schmidt, Burkhard; Schäffer, Andreas; Schwarzbauer, Jan

    2013-07-01

    The incorporation process of a defined (13)C- and (14)C-labeled nonylphenol isomer (4-(3,5-dimethylhept-3-yl)phenol) into soil-derived organo-clay complexes was investigated. Isolated organo-clay complexes were separated into humic subfractions. Noninvasive ((13)C-CP/MAS NMR) and invasive methods (sequential chemical degradation, pyrolysis) were applied to obtain detailed information about the mode of incorporation, chemical structure, and change of the incorporation character of nonextractable residues in course of incubation. (13)C-CP/MAS NMR measurements of humic acids revealed an increasing incorporation of phenolic compounds during the experimental time which was referred to residues of the introduced (13)C-labeled NP isomer. Detailed investigations by means of sequential chemical degradation indicated a predominant incorporation of nonextractable NP isomer residues via reversible ester (amide) bonds. In course of time, the amount of releasable compounds decreased, pointing to altering processes which affected the mode of incorporation. BBr3-treatment, RuO4 oxidation, and thermochemolysis released only low portions of nonextractable radioactivity giving evidence of strongly incorporated residues. With the comprehensive application of complementary methods (e.g., humic matter fractionation, (13)C-CP/MAS NMR, sequential chemical degradation) it was possible to provide a comparatively detailed insight into the incorporation behavior of the applied NP isomer. PMID:23713749

  9. 2-Methyl-aspartic acid monohydrate.

    PubMed

    Brewer, Greg; Burton, Aaron S; Dworkin, Jason P; Butcher, Ray J

    2013-11-30

    The title compound, C5H9NO4·H2O, is an isomer of the α-amino acid glutamic acid that crystallizes from water in its zwitterionic form as a monohydrate. It is not one of the 20 proteinogenic α-amino acids that are used in living systems and differs from the natural amino acids in that it has an α-methyl group rather than an α-H atom. In the crystal, an O-H⋯O hydrogen bond is present between the acid and water mol-ecules while extensive N-H⋯O and O-H⋯O hydrogen bonds link the components into a three-dimensional array. PMID:24454270

  10. Stacking and separation of coproporphyrin isomers by acetonitrile-salt mixtures in micellar electrokinetic chromatography.

    PubMed

    So, T S; Jia, L; Huie, C W

    2001-07-01

    The effectiveness of the addition of salt and acetonitrile in the sample matrix to induce narrowing of the analyte zones is demonstrated for the first time in micellar electrokinetic chromatography (MEKC). Using coproporphyrin (CP) I and III isomers as test compounds, the use of sodium cholate (SC) as the micelle in the separation buffer and a high concentration of sodium chloride in the aqueous sample solution (without the presence of an organic solvent) were found to provide enhancement in peak heights for both CP I and III, but yielded very poor resolution of these two positional isomers at sample size of 10% capillary volume or larger. With the addition of acetonitrile as the organic solvent in the aqueous sample solution (acetonitrile-salt mixtures), baseline/partial resolution of CP I and III was obtained even at large injection volumes, along with significant increase in peak heights for both isomers. Possible mechanisms responsible for the narrowing of analyte zones are briefly discussed. The effects of experimental parameters, such as concentrations of salt and acetonitrile, on peak heights and resolution of the test compounds were studied. Importantly, the usefulness of the present method was demonstrated for the MEKC determination of endogenous CP I and III present in normal urine samples with good separation and detection performances. PMID:11504047

  11. Precursor anion states in dissociative electron attachment to chlorophenol isomers

    NASA Astrophysics Data System (ADS)

    Kossoski, F.; Varella, M. T. do N.

    2016-07-01

    We report a theoretical study on low-energy (<10 eV) elastic electron scattering from chlorophenol isomers, namely, para-chlorophenol (pCP), meta-chlorophenol (mCP), and ortho-chlorophenol (oCP). The calculations were performed with the Schwinger multichannel method with pseudopotentials, and analysis of the computed integral cross sections and virtual orbitals revealed one σCCl ∗ , one σOH ∗ , and three π∗ shape resonances. We show that electron capture into the two lower lying π∗ orbitals initiates dissociative processes that lead to the elimination of the chloride ion, accounting for the two overlapping peaks where this fragment was observed. Despite the relatively small differences on the energetics of the π∗ resonances, a major isomeric effect was found on their corresponding autodetachment lifetimes, which accounts for the observed increasing cross sections in the progression pCP < mCP < oCP. In particular, dissociation from the π1 ∗ anion of pCP is largely suppressed because of the unfavorable mixing with the σCCl ∗ state. We found the intramolecular hydrogen bond present in oCP to have the opposite effects of stabilizing the σCCl ∗ resonance and destabilizing the σOH ∗ resonance. We also suggest that the hydrogen abstraction observed in chlorophenols and phenol actually takes place by a mechanism in which the incoming electron is directly attached to the dissociative σOH ∗ orbital.

  12. A new high-spin isomer in 195Bi

    NASA Astrophysics Data System (ADS)

    Roy, T.; Mukherjee, G.; Madhavan, N.; Rana, T. K.; Bhattacharya, Soumik; Asgar, Md. A.; Bala, I.; Basu, K.; Bhattacharjee, S. S.; Bhattacharya, C.; Bhattacharya, S.; Bhattacharyya, S.; Gehlot, J.; Ghugre, S. S.; Gurjar, R. K.; Jhingan, A.; Kumar, R.; Muralithar, S.; Nath, S.; Pai, H.; Palit, R.; Raut, R.; Singh, R. P.; Sinha, A. K.; Varughese, T.

    2015-11-01

    A new high-spin isomer has been identified in 195Bi at the focal plane of the HYbrid Recoil mass Analyser (HYRA) used in the gas-filled mode. The fusion evaporation reactions 169Tm (30Si, x n) 193, 195Bi were used with the beam energies on targets of 168 and 146MeV for 6n and 4n channels, respectively. The evaporation residues, separated from the fission fragments, and their decays were detected at the focal plane of HYRA using MWPC, Si-Pad and clover HPGe detectors. The half-life of the new isomer in 195Bi has been measured to be 1.6(1)μs. The configuration of the new isomer has been proposed and compared with the other isomers in this region. The Total Routhian Surface (TRS) calculations for the three-quasiparticle configurations corresponding to the new isomer suggest an oblate deformation for this isomeric state. The same calculations for different configurations in 195Bi and for the even-even 194Pb core indicate that the proton i 13/2 orbital has a large shape driving effect towards oblate shape in these nuclei.

  13. Behavioral and electrophysiological responses of Aedes albopictus to certain acids and alcohols present in human skin emanations.

    PubMed

    Guha, Lopamudra; Seenivasagan, T; Iqbal, S Thanvir; Agrawal, O P; Parashar, B D

    2014-10-01

    Human skin emanations attract hungry female mosquitoes toward their host for blood feeding. In this study, we report the flight orientation and electroantennogram response of Aedes albopictus females to certain unsaturated acids and alcohols found in human skin. In the Y-tube olfactometer, odors of lactic acid and 2-methyl-3-pentanol attracted 54-65% of Ae. albopictus females at all doses in a dose-dependent manner. However, at the highest dose (10(-2) g), the acids repelled 40-45% females. Attractancy (ca. 62-68%) at lower doses and repellency (ca. 30-45%) at higher doses were recorded for 3-methyl-3-pentanol and 1-octen-3-ol, while 5-hexen-1-ol, cis-2-hexen-1-ol, and trans 2-hexen-1-ol odor repelled ca. 55-65% of Ae. albopictus females at all doses. Antenna of female Ae. albopictus exhibited a dose-dependent EAG response up to 10(-3) g of L-lactic acid, trans-2-methyl-2-pentenoic acid, 2-octenoic acid, trans-2-hexen-1-ol and 1-octen-3-ol stimulations; however, the highest dose (10(-2) g) caused a little decline in the EAG response. EAG response of 9-10-fold was elicited by lactic acid, 2-octenoic acid, trans-2-hexenoic acid, and 3-methyl-3-pentanol, while cis-2-hexen-1-ol and trans-2-methyl pentenoic acid elicited 1-5-fold responses compared to solvent control. A blend of attractive compounds could be utilized in odor-baited trap for surveillance and repellent molecules with suitable formulation could be used to reduce the biting menace of mosquitoes. PMID:25049052

  14. Reaction kinetics in dehydrochlorination of. cap alpha. -isomer of hexachlorocyclohexane in the presence of a phase transfer catalyst

    SciTech Connect

    Sirovskii, F.S.; Chimishkyan, A.L.; Panova, M.V.; Treger, Y.A.; Velichko, S.M.

    1986-01-01

    This paper presents a kinetic study of the reaction of aqueous caustic dehydrochlorination of the alpha-isomer of hexachlorocyclohexane (alpha-HCCH) with catalysis by tetrabutyl-ammonium hydroxide. It has been shown that the process is described by a scheme of phase transfer catalysis.

  15. Retinal isomer composition in some bacteriorhodopsin mutants under light and dark adaptation conditions

    SciTech Connect

    Song, L.; Yang, D.; El-Sayed, M.A.; Lanyi, J.K.

    1995-06-15

    The isomeric composition of retinal was measured in a number of bacteriorhodopsin (bR) mutants (D85N, D212N, R82A, Y185F, and D115N) under various conditions, using a rapid retinal extraction technique followed by HPLC analysis. Besides the 13-cis and the all-trans retinal isomers observed in wild type (wt) bR under physiological conditions, the 11-cis and 9-cis retinal isomers were observed in variable but minor amounts in the bR mutants. In addition, the values of the equilibrium constant at two temperatures and the enthalpy change for the all-trans to 13-cis isomerization process in the dark-adapted state of D212N, D85N, deionized blue bR, and wt bR were determined. We find that perturbation of the retinal cavity (pocket) by residue replacement changes the relative thermal stability of the different retinal isomers, allowing for thermal-and/or photoisomerization of the retinal chromophore along C{sub 9}-C{sub 10} and C{sub 11}-C{sub 12} bonds to moderately compete with the isomerization around the C{sub 13}-C{sub 14} bond. The bR mutants expressed in Halobacterium salinarium studied in the present work showed normal 13-cis to all-trans light adaptation, in contrast with abnormal all-trans to 13-cis light adaptation observed for D212E, D212A, and D212N expressed in Escherichia coli, suggesting an influence of the purple membrane lattice and/or the lipids on the stability of the different retinal isomers within the protein. 38 refs., 2 tabs.

  16. Low and High Temperature Combustion Chemistry of Butanol Isomers in Premixed Flames and Autoignition Systems

    SciTech Connect

    Sarathy, S M; Pitz, W J; Westbrook, C K; Mehl, M; Yasunaga, K; Curran, H J; Tsujimura, T; Osswald, P; Kohse-Hoinghaus, K

    2010-12-12

    Butanol is a fuel that has been proposed as a bio-derived alternative to conventional petroleum derived fuels. The structural isomer in traditional 'bio-butanol' fuel is n-butanol, but newer conversion technologies produce iso-butanol as a fuel. In order to better understand the combustion chemistry of bio-butanol, this study presents a comprehensive chemical kinetic model for all the four isomers of butanol (e.g., 1-, 2-, iso- and tert-butanol). The proposed model includes detailed high temperature and low temperature reaction pathways. In this study, the primary experimental validation target for the model is premixed flat low-pressure flame species profiles obtained using molecular beam mass spectrometry (MBMS). The model is also validated against previously published data for premixed flame velocity and n-butanol rapid compression machine and shock tube ignition delay. The agreement with these data sets is reasonably good. The dominant reaction pathways at the various pressures and temperatures studied are elucidated. At low temperature conditions, we found that the reaction of alphahydroxybutyl with O{sub 2} was important in controlling the reactivity of the system, and for correctly predicting C{sub 4} aldehyde profiles in low pressure premixed flames. Enol-keto isomerization reactions assisted by HO{sub 2} were also found to be important in converting enols to aldehydes and ketones in the low pressure premixed flames. In the paper, we describe how the structural features of the four different butanol isomers lead to differences in the combustion properties of each isomer.

  17. Separation of branched hexane isomers using zeolite molecular sieves

    SciTech Connect

    Huddersman, K.; Klimczyk, M.

    1996-02-01

    A range of small, medium and large pore zeolite, and their modified forms are studied for their ability to separate di- from monobranched isomers of hexane. The separation studies are carried out using high-temperature (250--350 C) gas chromatography. Beta(H,Ba) is found to be the most effective separator of 2,3-dimethylbutane and 3-methyl-pentane and is therefore studied for its sorption capacities toward the two hexane isomers. This work is directed to the improvement of the quality of petrol by separating hydrocarbon mixtures using zeolites. Since maximum hydrocarbon branching is desirable in petrol (hydrocarbons with a branching structure burn more efficiently and thus have a higher octane rating), catalytic isomerization is used to isomerize straight-chain hydrocarbons to their mono- or dibranched isomers.

  18. FY2010 Annual Report for the Actinide Isomer Detection Project

    SciTech Connect

    Warren, Glen A.; Francy, Christopher J.; Ressler, Jennifer J.; Erikson, Luke E.; Miller, Erin A.; Hatarik, R.

    2011-01-01

    This project seeks to identify a new signature for actinide element detection in active interrogation. This technique works by exciting and identifying long-lived nuclear excited states (isomers) in the actinide isotopes and/or primary fission products. Observation of isomers in the fission products will provide a signature for fissile material. For the actinide isomers, the decay time and energy of the isomeric state is unique to a particular isotope, providing an unambiguous signature for Special Nuclear Materials (SNM). Future work will include a follow-up measurement scheduled for December 2010 at LBNL. Lessons learned from the July 2010 measurements will be incorporated into these new measurements. Analysis of both the July and December experiments will be completed in a few months. A research paper to be submitted to a peer-reviewed journal will be drafted if the conclusions from the measurements warrant publication.

  19. Spectroscopy of {sup 144}Ho using recoil-isomer tagging

    SciTech Connect

    Mason, P. J. R; Cullen, D. M.; Scholey, C.; Greenlees, P. T.; Jakobsson, U.; Jones, P. M.; Julin, R.; Juutinen, S.; Ketelhut, S.; Leino, M.; Nyman, M.; Peura, P.; Puurunen, A.; Rahkila, P.; Ruotsalainen, P.; Sorri, J.; Saren, J.; Uusitalo, J.; Xu, F. R.

    2010-02-15

    Excited states in the proton-unbound odd-odd nucleus {sup 144}Ho have been populated using the {sup 92}Mo({sup 54}Fe,pn){sup 144}Ho reaction and studied using the recoil-isomer-tagging technique. The alignment properties and signature splitting of the rotational band above the I{sup p}i=(8{sup +}){sup 144m}Ho isomer have been analyzed and the isomer confirmed to have a pih{sub 11/2} x nuh{sub 11/2} two-quasiparticle configuration. The configuration-constrained blocking method has been used to calculate the shapes of the ground and isomeric states, which are both predicted to have triaxial nuclear shapes with |gamma|approx =24 deg.

  20. Oxidation and combustion of the n-hexene isomers: a wide range kinetic modeling study

    SciTech Connect

    Mehl, M; Vanhove, G; Pitz, W J; Ranzi, E

    2008-03-12

    A detailed chemical kinetic mechanism has been developed to study the oxidation of the straight-chain isomers of hexene over a wide range of operating conditions. The main features of this detailed kinetic mechanism, which includes both high and low temperature reaction pathways, are presented and discussed with special emphasis on the main classes of reactions involved in alkene oxidation. Simulation results have been compared with experimental data over a wide range of operating conditions including shock tube, jet stirred reactor and rapid compression machine. The different reactivities of the three isomers have been successfully predicted by the model. Isomerization reactions of the hexenyl radicals were found to play a significant role in the chemistry and interactions of the three n-hexene isomers. A comparative reaction flux analysis is used to verify and discuss the fundamental role of the double bond position in the isomerization reactions of alkenyl radicals, as well as the impact of the allylic site in the low and high temperature mechanism of fuel oxidation.

  1. Investigation of a recently detected 11-nor-9-carboxy-Δ(9)-tetrahydrocannabinol isomer: Studies on the degradation of 11-nor-9-carboxy-Δ(9)-tetrahydrocannabinol glucuronide.

    PubMed

    Hanisch, Stephanie; Paulke, Alexander; Toennes, Stefan W

    2016-09-10

    An isomer of the tetrahydrocannabinol (THC) metabolite 11-nor-9-carboxy-Δ(9)-THC (THCCOOH) had been detected in blood of cannabis users. The present study was initiated to elucidate whether the labile metabolite THCCOOH-glucuronide could be the precursor. THCCOOH-glucuronide was incubated in human serum and albumin (HSA) solution at various temperatures (-18, 4.5, 22 and 37°C) and pH values (pH 7.4 and 8.3) for seven days in the presence or absence of the esterase inhibitor sodium fluoride. Analysis of incubation samples was performed using LC-MS/MS. Marked degradation of THCCOOH-glucuronide was observed at 37°C. It was found that not only THCCOOH, but also the isomer is a degradation product of THCCOOH-glucuronide and its in-vivo production is assumed. Degradation to THCCOOH and the isomer occurred at alkaline pH, in the presence of fluoride-sensitive esterases and of HSA alone. To inhibit isomer formation during sample storage, refrigeration and controlling of the pH are recommended. However, THCCOOH and the isomer exhibit similar properties during incubations in serum, but differ in their interaction with HSA. The present study confirmed the nature of the isomer as degradation product of the abundant THC metabolite THCCOOH-glucuronide. Serum albumin and esterases are obviously involved. The isomer is formed not only during storage, but also under physiological conditions, suggesting that it can be considered an in-vivo metabolite. However, the chemical structure of the isomer remains unknown and further research is necessary. PMID:27448313

  2. Isomers of glucosaminylphosphatidylglycerol in Bacillus megaterium

    PubMed Central

    MacDougall, J. C.; Phizackerley, P. J. R.

    1969-01-01

    1. The lipids of Bacillus megaterium were extracted and three lipids containing glucosamine were identified. One of these is not a phospholipid, but the other two, which differ in their chromatographic behaviour, contain phosphorus, glycerol, fatty acid and d-glucosamine in the molar proportions 1:2:2:1. 2. In both phosphoglycolipids, the fatty acids are bound in ester linkage, and both yield 2,5-anhydromannose and 3-sn-phosphatidyl-1′-sn-glycerol on treatment with sodium nitrite. 3. Both phosphoglycolipids were N-acetylated and, after removal of fatty acids by mild alkaline hydrolysis, in both cases N-acetylglucosamine was quantitatively released by β-N-acetylhexosaminidase. 4. The glucosaminylglycerols derived from the two phosphoglycolipids by partial acid hydrolysis differ in their behaviour towards periodate. In one case 1 mole of periodate is rapidly consumed/mole of glucosaminylglycerol, but in the other case under identical conditions the consumption of periodate is negligible. 5. The phosphoglycolipids were identified as 1′-(1,2-diacyl-sn-glycero-3-phosphoryl)-3′-O-β-(2-amino-2-deoxy-d-glucopyranosyl)-sn-glycerol and as 1′-(1,2-diacyl-sn-glycero-3-phosphoryl)-2′-O-β-(2-amino-2-deoxy-d-glucopyranosyl)-sn-glycerol. 6. Both phosphoglycolipids are good substrates for phospholipase A: neither is a substrate for phospholipase C from Clostridium perfringens, and only the 3′-glucosaminide is a substrate for phospholipase D. PMID:4309309

  3. Anaerobic degradation of phthalate isomers by methanogenic consortia

    SciTech Connect

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

    1999-03-01

    Three methanogenic enrichment cultures, grown on ortho-phthalate, iso-phthalate, or terephthalate were obtained from digested sewage sludge or methanogenic granular sludge. Cultures grown on one of the phthalate isomers were not capable of degrading the other phthalate isomers. All three cultures had the ability to degrade benzoate. Maximum specific growth rates ({mu}{sub S}{sup max}) and biomass yields (Y{sub X{sub tot}S}) of the mixed cultures were determined by using both the phthalate isomers and benzoate as substrates. Comparable values for these parameters were found for all three cultures. Values for {mu}{sub X}{sup max} and Y{sub X{sub tot}S} were higher for growth on benzoate compared to the phthalate isomers. Based on measured and estimated values for the microbial yield of the methanogens in the mixed culture, specific yields for the phthalate and benzoate fermenting organisms were calculated. A kinetic model, involving three microbial species, was developed to predict intermediate acetate and hydrogen accumulation and the final production of methane. Values for the ratio of the concentrations of methanogenic organisms, versus the phthalate isomer and benzoate fermenting organisms, and apparent half-saturation constants (K{sub S}) for the methanogens were calculated. By using this combination of measured and estimated parameter values, a reasonable description of intermediate accumulation and methane formation was obtained, with the initial concentration of phthalate fermenting organisms being the only variable. The energetic efficiency for growth of the fermenting organisms on the phthalate isomers was calculated to be significantly smaller than for growth on benzoate.

  4. Exotic SiO2H2 Isomers: Theory and Experiment Working in Harmony.

    PubMed

    McCarthy, Michael C; Gauss, Jürgen

    2016-05-19

    Replacing carbon with silicon can result in dramatic and unanticipated changes in isomeric stability, as the well-studied CO2H2 and the essentially unknown SiO2H2 systems illustrate. Guided by coupled-cluster calculations, three SiO2H2 isomers have been detected and spectroscopically characterized in a molecular beam discharge source using rotational spectroscopy. The cis,trans conformer of dihydroxysilylene HOSiOH, the ground-state isomer, and the high-energy, metastable dioxasilirane c-H2SiO2 are abundantly produced in a dilute SiH4/O2 electrical discharge, enabling precise structural determinations of both by a combination of isotopic measurements and calculated vibrational corrections. The isotopic studies also provide insight into their formation route, suggesting that c-H2SiO2 is formed promptly in the expansion but that cis,trans-HOSiOH is likely formed by secondary reactions following formation of the most stable dissociation pair, SiO + H2O. Although less abundant, the rotational spectrum of trans-silanoic acid, the silicon analogue of formic acid, HSi(O)OH, has also been observed. PMID:27139016

  5. Characterization of epoxydecenal isomers as potent odorants in black tea (Dimbula) infusion.

    PubMed

    Kumazawa, Kenji; Wada, Yoshiyuki; Masuda, Hideki

    2006-06-28

    In a black tea (Dimbula) infusion, the potent "sweet and/or juicy" odorants were identified as the cis- and trans-4,5-epoxy-(E)-2-decenals by comparison of their gas chromatography retention indices, mass spectra, and odor quality to those of the actual synthetic compounds. Of the two odorants, cis-4,5-epoxy-(E)-2-decenal has been identified for the first time in the black tea. On the basis of the aroma extract dilution analysis on the flavor distillate obtained using the solvent-assisted flavor evaporation technique from the black tea infusion, these isomers showed higher flavor dilution (FD) factors. The FD factors and concentrations of these odorants in the black tea infusion were observed to be much higher than those from Japanese green tea. In addition, the model studies showed that these odorants were generated from linoleic acid and its hydroperoxides by heating, but the generated amounts of these odorants from linoleic acid were much less than those of its hydroperoxides. It can be assumed from these results that the withering and fermentation, which are characteristic processes during the manufacturing of the black tea, which includes the enzymatic reaction such as lipoxygenase, is one of the most important factors for the formation of the epoxydecenal isomers. PMID:16787030

  6. Multifunctional Hyaluronic Acid and Chondroitin Sulfate Nanoparticles: Impact of Glycosaminoglycan Presentation on Receptor Mediated Cellular Uptake and Immune Activation.

    PubMed

    Oommen, Oommen P; Duehrkop, Claudia; Nilsson, Bo; Hilborn, Jöns; Varghese, Oommen P

    2016-08-17

    Hyaluronic acid (HA) and chondroitin sulfate (CS) polymers are extensively used for various biomedical applications, such as for tissue engineering, drug delivery, and gene delivery. Although both these biopolymers are known to target cell surface CD44 receptors, their relative cellular targeting properties and immune activation potential have never been evaluated. In this article, we present the synthesis and characterization of novel self-assembled supramolecular HA and CS nanoparticles (NPs). These NPs were developed using fluorescein as a hydrophobic component that induced amphiphilicity in biopolymers and also efficiently stabilized anticancer drug doxorubicin (DOX) promoting a near zero-order drug release. The cellular uptake and cytotoxicity studies of these NPs in different human cancer lines, namely, human colorectal carcinoma cell line HCT116 and human breast cancer cell line MCF-7 demonstrated dose dependent cytotoxicity. Interestingly, both NPs showed CD44 dependent cellular uptake with the CS-DOX NP displaying higher dose-dependent cytotoxicity than the HA-DOX NP in different mammalian cells tested. Immunological evaluation of these nanocarriers in an ex vivo human whole blood model revealed that unlike unmodified polymers, the HA NP and CS NP surprisingly showed platelet aggregation and thrombin-antithrombin complex formation at high concentrations (0.8 mg/mL). We also observed a clear difference in early- and late-stage complement activation (C3a and sC5b-9) with CS and CS NP triggering significant complement activation at high concentrations (0.08-0.8 mg/mL), unlike HA and HA NP. These results offer new insight into designing glycosaminoglycan-based NPs and understanding their hematological responses and targeting ability. PMID:27468113

  7. Computation of Mössbauer isomer shifts from first principles

    NASA Astrophysics Data System (ADS)

    Zwanziger, J. W.

    2009-05-01

    Computation of the observables of a Mössbauer spectrum, primarily the isomer shift, from a first-principles approach is described. The framework used is density functional theory using the projector augmented wave formalism (DFT PAW), which enables efficient computation even of many-electron solids such as SnCl2. The proper PAW version of the isomer shift is derived and shown to be correct through comparison of computed shifts and experiment in a variety of compounds based on tin, germanium and zinc. The effects of pressure are considered as well as motional effects including the Lamb-Mössbauer factor and the second-order Doppler shift.

  8. Synthesis and characterization of tetrakis-silylated C60 isomers.

    PubMed

    Maeda, Yutaka; Rahman, G M Aminur; Wakahara, Takatsugu; Kako, Masahiro; Okamura, Mutsuo; Sato, Soichi; Akasaka, Takeshi; Kobayashi, Kaoru; Nagase, Shigeru

    2003-08-22

    A photochemical reaction of C(60) with disilane in a 2:3 ratio affords the isomer mixture of the tetrakis-adduct of C(60)((t)BuPh(2)Si)(4) as the major product. The use of a three-stage HPLC separation system isolated three of their isomers. Their structural assignments were based on FAB mass, UV-vis, NMR, and cyclic voltammetry (CV) measurements. The CV analysis showed that the terakis-adduct has lower oxidation and higher reduction potentials than the bis-adduct C(60)((t)BuPh(2)Si)(2) and the parent C(60). PMID:12919050

  9. Differentiation of optical isomers through enhanced weak-field interactions

    NASA Technical Reports Server (NTRS)

    Aronowitz, S.

    1980-01-01

    The influence of weak field interaction terms due to the cooperative effects which arise from a macroscopic assemblage of interacting sites is studied. Differential adsorption of optical isomers onto an achiral surface is predicted to occur if the surface was continuous and sufficiently large. However, the quantity of discontinuous crystal surfaces did not enhance the percentage of differentiation and thus the procedure of using large quantities of small particles was not a viable technique for obtaining a detectable differentiation of optical isomers on an achiral surface.

  10. The bioaccumulation and fate of a branched 14C-p-nonylphenol isomer in Lymnaea stagnalis L.

    PubMed

    Lalah, Joseph O; Behechti, Akbar; Severin, Gabriele F; Lenoir, Dieter; Günther, Klaus; Kettrup, Antonius; Schramm, Karl-Werner

    2003-07-01

    A single branched isomer of p-nonylphenol, 4(3',6'-dimethyl-3'-heptyl)-phenol, previously identified by gas chromatography-mass spectrometry as one of the major constituent isomers in p-nonylphenol (constituting approximately 10% of all its isomers), was synthesized and used in studies of its bioaccumulation and excretion in the hermophroditic pond snail Lymnaea stagnalis L. Branched isomers of nonylphenol are perceived to have more estrogenlike toxicity than the straight-chain isomers in addition to being more resistant to biodegradation in the environment. With an average static exposure concentration of 104 microg/L (range: 92-116 microg/L) in water at 19 degrees C for 8 d, the uptake of the compound was found to be fairly rapid, reaching a peak concentration of 23,548 microg/kg of whole tissue wet weight after 5 d and a peak bioaccumulation factor (BAFw) of 242 (5,562, based on lipid weight) after 3 d. The uptake data fitted into a logarithmic expression C(t) = 5,231 ln(t) + 11,956, where C(t) is the amount of residues accumulated in whole tissue in micrograms per kilogram tissue wet weight after a period of time, t, and t is the period of exposure in days. By determination of the excretion of 14C-residues released in water and in feces, an average loss of 96% of the accumulated residues was achieved after 22 d of continuous exposure to clean water. By first-order kinetics analysis of the excretion data, an average half-life of excretion of 4.9 d was obtained. By high-performance liquid chromatography and gas-liquid chromatography-mass spectrometry, a catechol metabolite, 4(3',6'-dimethyl-3'-heptyl)-catechol, was detected in tissue extracts (after hydrolysis with beta-glucuronidase) and in feces, in addition to the parent isomer, suggesting that the isomer may have been metabolized by glucuronic acid conjugation and hydroxylation at the ortho position of its phenolic ring. PMID:12836966

  11. A maize death acid, 10-oxo-11-phytoenoic acid, is the predominant cyclopentenone signal present during multiple stress and developmental conditions

    PubMed Central

    Christensen, Shawn A.; Huffaker, Alisa; Hunter, Charles T.; Alborn, Hans T.; Schmelz, Eric A.

    2016-01-01

    abstract Recently we investigated the function of the 9-lipoxygenase (LOX) derived cyclopentenones 10-oxo-11-phytoenoic acid (10-OPEA) and 10-oxo-11,15-phytodienoic acid (10-OPDA) and identified their C-14 and C-12 derivatives. 10-OPEA accumulation is elicited by fungal and insect attack and acts as a strong inhibitor of microbial and herbivore growth. Although structurally similar, comparative analyses between 10-OPEA and its 13-LOX analog 12-oxo-phytodienoic acid (12-OPDA) demonstrate specificity in transcript accumulation linked to detoxification, secondary metabolism, jasmonate regulation, and protease inhibition. As a potent cell death signal, 10-OPEA activates cysteine protease activity leading to ion leakage and apoptotic-like DNA fragmentation. In this study we further elucidate the distribution, abundance, and functional roles of 10-OPEA, 10-OPDA, and 12-OPDA, in diverse organs under pathogen- and insect-related stress. PMID:26669723

  12. Acidic deposition and its effects on forest productivity: a review of the present state of knowledge, research activities, and information needs

    SciTech Connect

    Pinkerton, J.E.

    1981-01-01

    The present state of knowledge with regard to acid deposition is reviewed. Sources include the literature and direct contact with persons responsible for carrying out all completed, ongoing, and planned research activities, national and international, related to acidic deposition and its effects, with emphasis on forest productivity. In addition, a list of information needs in seven areas was developed, these include: a characterization of forest soils to define their sensitivity to acidic deposition; effects on forest soil chemical and biological processes; development of improved dry deposition measurement methods; changes in precipitation composition due to forest canopies; more extensive monitoring of acidic deposition in industry owned forest lands; expansion of long-term greenhouse and controlled field experiments; and the relationship of acidic deposition and intensive forestry management practices. 85 references. (MDF)

  13. The spectroscopy and photochemistry of quinioline structural isomers: (E)- and (Z)-phenylvinylnitrile

    NASA Astrophysics Data System (ADS)

    Mehta-Hurt, Deepali N.; Korn, Joseph A.; Navotnaya, Polina; Parobek, Alexander P.; Clayton, Rachel M.; Zwier, Timothy S.

    2015-08-01

    In Titan's atmosphere, photochemical pathways that lead to nitrogen heteroaromatics may incorporate photoisomerization of their structural isomers as a final step. (E)- and (Z)-phenylvinylnitrile ((E)- and (Z)-PVN, C6H5 —CH=CHCN) are structural isomers of quinoline that themselves possess extensive absorptions in the ultraviolet, and thus may engage in such photoisomerization pathways. The present study explores the vibronic spectroscopy and photo-induced isomerization of gas-phase (E)- and (Z)-PVN in the 33,600-35,850 cm-1 region under jet-cooled conditions. The S0-S1 origins for (E)- and (Z)-PVN have been identified at 33 827 cm-1 and 33 707 cm-1, respectively. Isomer-specific UV-UV hole-burning and UV depletion spectra reveal sharp vibronic structure that extends over almost 2000 cm-1, with thresholds for fast non-radiative decay identified by a comparison between hole-burning and UV depletion spectra. Dispersed fluorescence spectra of the two isomers enable the assignment of many low frequency transitions in both molecules, aided by harmonic frequency calculations (B3LYP/6-311++G(d,p)) and a comparison with the established spectroscopy of phenylvinylacetylene, the ethynyl counterpart to PVN. Both isomers are proven to be planar in both the S0 ground and S1 electronic excited states. (E)-PVN exhibits extensive Duschinsky mixing involving out-of-plane modes whose frequencies and character change significantly in the ππ∗ transition, which modulates the degree of single- and double-bond character along the vinylnitrile substituent. This same mixing is much less evident in (Z)-PVN. The spectroscopic characterization of (E)- and (Z)-PVN served as the basis for photoisomerization experiments using ultraviolet hole-filling spectroscopy carried out in a reaction tube affixed to the pulsed valve. Successful interconversion between (E) and (Z)-PVN was demonstrated via ultraviolet hole-filling experiments. Photoexcitation of (E)- and (Z)-PVN at their respective S0-S1

  14. The spectroscopy and photochemistry of quinioline structural isomers: (E)- and (Z)-phenylvinylnitrile.

    PubMed

    Mehta-Hurt, Deepali N; Korn, Joseph A; Navotnaya, Polina; Parobek, Alexander P; Clayton, Rachel M; Zwier, Timothy S

    2015-08-21

    In Titan's atmosphere, photochemical pathways that lead to nitrogen heteroaromatics may incorporate photoisomerization of their structural isomers as a final step. (E)- and (Z)-phenylvinylnitrile ((E)- and (Z)-PVN, C6H5-CH=CHCN) are structural isomers of quinoline that themselves possess extensive absorptions in the ultraviolet, and thus may engage in such photoisomerization pathways. The present study explores the vibronic spectroscopy and photo-induced isomerization of gas-phase (E)- and (Z)-PVN in the 33,600-35,850 cm(-1) region under jet-cooled conditions. The S0-S1 origins for (E)- and (Z)-PVN have been identified at 33 827 cm(-1) and 33 707 cm(-1), respectively. Isomer-specific UV-UV hole-burning and UV depletion spectra reveal sharp vibronic structure that extends over almost 2000 cm(-1), with thresholds for fast non-radiative decay identified by a comparison between hole-burning and UV depletion spectra. Dispersed fluorescence spectra of the two isomers enable the assignment of many low frequency transitions in both molecules, aided by harmonic frequency calculations (B3LYP/6-311++G(d,p)) and a comparison with the established spectroscopy of phenylvinylacetylene, the ethynyl counterpart to PVN. Both isomers are proven to be planar in both the S0 ground and S1 electronic excited states. (E)-PVN exhibits extensive Duschinsky mixing involving out-of-plane modes whose frequencies and character change significantly in the ππ* transition, which modulates the degree of single- and double-bond character along the vinylnitrile substituent. This same mixing is much less evident in (Z)-PVN. The spectroscopic characterization of (E)- and (Z)-PVN served as the basis for photoisomerization experiments using ultraviolet hole-filling spectroscopy carried out in a reaction tube affixed to the pulsed valve. Successful interconversion between (E) and (Z)-PVN was demonstrated via ultraviolet hole-filling experiments. Photoexcitation of (E)- and (Z)-PVN at their respective S0

  15. The spectroscopy and photochemistry of quinioline structural isomers: (E)- and (Z)-phenylvinylnitrile

    SciTech Connect

    Mehta-Hurt, Deepali N.; Korn, Joseph A.; Navotnaya, Polina; Parobek, Alexander P.; Clayton, Rachel M.; Zwier, Timothy S.

    2015-08-21

    In Titan’s atmosphere, photochemical pathways that lead to nitrogen heteroaromatics may incorporate photoisomerization of their structural isomers as a final step. (E)- and (Z)-phenylvinylnitrile ((E)- and (Z)-PVN, C{sub 6}H{sub 5} —CH=CHCN) are structural isomers of quinoline that themselves possess extensive absorptions in the ultraviolet, and thus may engage in such photoisomerization pathways. The present study explores the vibronic spectroscopy and photo-induced isomerization of gas-phase (E)- and (Z)-PVN in the 33,600-35,850 cm{sup −1} region under jet-cooled conditions. The S{sub 0}-S{sub 1} origins for (E)- and (Z)-PVN have been identified at 33 827 cm{sup −1} and 33 707 cm{sup −1}, respectively. Isomer-specific UV-UV hole-burning and UV depletion spectra reveal sharp vibronic structure that extends over almost 2000 cm{sup −1}, with thresholds for fast non-radiative decay identified by a comparison between hole-burning and UV depletion spectra. Dispersed fluorescence spectra of the two isomers enable the assignment of many low frequency transitions in both molecules, aided by harmonic frequency calculations (B3LYP/6-311++G(d,p)) and a comparison with the established spectroscopy of phenylvinylacetylene, the ethynyl counterpart to PVN. Both isomers are proven to be planar in both the S{sub 0} ground and S{sub 1} electronic excited states. (E)-PVN exhibits extensive Duschinsky mixing involving out-of-plane modes whose frequencies and character change significantly in the ππ{sup ∗} transition, which modulates the degree of single- and double-bond character along the vinylnitrile substituent. This same mixing is much less evident in (Z)-PVN. The spectroscopic characterization of (E)- and (Z)-PVN served as the basis for photoisomerization experiments using ultraviolet hole-filling spectroscopy carried out in a reaction tube affixed to the pulsed valve. Successful interconversion between (E) and (Z)-PVN was demonstrated via ultraviolet hole

  16. DNA-decorated carbon nanotube-based FETs as ultrasensitive chemical sensors: Discrimination of homologues, structural isomers, and optical isomers

    NASA Astrophysics Data System (ADS)

    Khamis, S. M.; Jones, R. A.; Johnson, A. T. C.; Preti, G.; Kwak, J.; Gelperin, A.

    2012-06-01

    We have explored the abilities of all-electronic DNA-carbon nanotube (DNA-NT) vapor sensors to discriminate very similar classes of molecules. We screened hundreds of DNA-NT devices against a panel of compounds chosen because of their similarities. We demonstrated that DNA-NT vapor sensors readily discriminate between series of chemical homologues that differ by single methyl groups. DNA-NT devices also discriminate among structural isomers and optical isomers, a trait common in biological olfactory systems, but only recently demonstrated for electronic FET based chemical sensors.

  17. Crystal and electronic structures of tris[4,4,4-Trifluoro-1-(2-X)-1,3-butanedionato]iron(III) isomers (X = thienyl or furyl): An X-ray and computational study

    NASA Astrophysics Data System (ADS)

    Conradie, Marrigje M.; van Rooyen, Petrus H.; Conradie, Jeanet

    2013-12-01

    DFT calculations showed that [Fe(acac)3] (where acac = acetylacetonato) is high-spin, with a negative D3 distortion from the octahedral ligand field. Calculations further showed that, although both the fac and mer isomers of complexes [Fe(CF3COCHCOR)3], where R = C4H3S or C4H3O, can exist, the mer isomers are energetically favoured in both complexes. The structure of the major mer isomer of [Fe(CF3COCHCOC4H3S)3] has been published previously, while the crystal structure of the minor fac isomer of [Fe(CF3COCHCOC4H3S)3] is presented in this study. The structure of the mer isomer of [Fe(CF3COCHCOC4H3O)3], in agreement with DFT calculations, showed that the furyl substituent pointed towards the CF3 group in a syn orientation.

  18. Diffusion ordered spectroscopy for resolution of double bonded cis, trans-isomers

    NASA Astrophysics Data System (ADS)

    Chaudhari, Sachin Rama; Suryaprakash, N.

    2012-06-01

    NMR spectroscopic separation of double bonded cis- and trans-isomers, that have different molecular shapes but identical mass have been carried out using Diffusion Ordered Spectroscopy (DOSY). The mixtures of fumaric acid and maleic acid, that have similar hydrodynamic radii, have resolved been 'on the basis of their diffusion coefficients arising due to their different tendencies to associate with micelles or reverse micelles. Sodium dodecyl sulfate (SDS) and Dioctyl sulfosuccinate sodium salt (AOT) have been used as the media to mimic the chromatographic conditions, modify the average mobility and to achieve differential diffusion rates. The best separation of the components has been achieved by Dioctyl sulfosuccinate sodium salt (AOT) in D2O solution.

  19. Enantioselective separation of defined endocrine-disrupting nonylphenol isomers.

    PubMed

    Acir, Ismail-Hakki; Wüst, Matthias; Guenther, Klaus

    2016-08-01

    Nonylphenol is in the focus of worldwide endocrine-disrupter research and accounted for as a priority hazardous substance of the Water Framework Directive of the European Union. Technical nonylphenol consists of a very complex mixture of isomers and enantiomers. As estrogenic effect and degradation behavior in environmental processes of single nonylphenols are heavily dependent on the structure of the nonyl side chain, it is absolutely necessary to consider the nonylphenol problem from an isomer and enantiomer-specific viewpoint. In this study, an enantiomer-specific separation of eight defined synthesized nonylphenol isomers by five different special chiral cyclodextrin columns was performed underivatized and after methylation, silylation, and acylation. This work demonstrates that three columns out of the investigated five show an excellent separation behavior for the studied different nonylphenol isomers and can be used for the enantiomer-specific determination of nonylphenols in food, other biological matrices, and environmental samples in the future. Graphical abstract Enantiomeric pair of 4-NP170 (4-[1-ethyl-1,3,3-trimethylbutyl]phenol). PMID:27236316

  20. Flexible metal–organic supramolecular isomers for gas separation

    SciTech Connect

    Motkuri, Radha K.; Tian, Jian; Thallapally, Praveen K.; Fernandez, Carlos A.; Dalgarno, Scott J.; Warren, John E.; McGrail, B. Peter; Atwood, Jerry L.

    2010-01-01

    Here in we report three porous metal-organic supramolecular isomers (PtS, Diamondoid and Lonsdaleite networks) generated from a single building block (tetrakis[4-(carboxyphenyl)oxamethyl]methane, 1), with the differences in solid-state packing, amount of gas uptake and selectivity towards other gases and so on

  1. Identification of position isomers by energy-resolved mass spectrometry.

    PubMed

    Menachery, Sunil Paul M; Laprévote, Olivier; Nguyen, Thao P; Aravind, Usha K; Gopinathan, Pramod; Aravindakumar, Charuvila T

    2015-07-01

    This study reports an energy-resolved mass spectrometric (ERMS) strategy for the characterization of position isomers derived from the reaction of hydroxyl radicals ((●)OH) with diphenhydramine (DPH) that are usually hard to differentiate by other methods. The isomer analogues formed by (●)OH attack on the side chain of DPH are identified with the help of a specific fragment ion peak (m/z 88) in the collision-induced dissociation (CID) spectrum of the protonated molecule. In the negative ion mode, the breakdown curves of the deprotonated molecules show an order of stability (supported by density functional theory (DFT) calculations) ortho > meta > para of the positional isomers formed by the hydroxylation of the aromatic ring. The gas phase stability of the deprotonated molecules [M - H](-) towards the benzylic cleavage depends mainly on the formation of intramolecular hydrogen bonds and of the mesomeric effect of the phenol hydroxyl. The [M - H](-) molecules of ortho and meta isomers result a peak at m/z 183 with notably different intensities because of the presence/absence of an intramolecular hydrogen bonding between the OH group and C9 protons. The ERMS approach discussed in this report might be an effective replacement for the conventional methods that requires very costly and time-consuming separation/purification methods along with the use of multi-spectroscopic methods. PMID:26349650

  2. Short-lived isomers in 192Po and 194Po

    NASA Astrophysics Data System (ADS)

    Andel, B.; Andreyev, A. N.; Antalic, S.; Heßberger, F. P.; Ackermann, D.; Hofmann, S.; Huyse, M.; Kalaninová, Z.; Kindler, B.; Kojouharov, I.; Kuusiniemi, P.; Lommel, B.; Nishio, K.; Page, R. D.; Sulignano, B.; Van Duppen, P.

    2016-06-01

    Isomeric states in 194Po and 192Po were studied at the velocity filter SHIP. The isotopes were produced in the fusion-evaporation reactions 141Pr(56Fe, p 2 n )194Po and 144Sm(51V, p 2 n )192Po . Several new γ -ray transitions were attributed to the isomers and γ -γ coincidences for both isomers were studied for the first time. The 459-keV transition earlier, tentatively proposed as de-exciting the isomeric level in 194Po, was replaced by a new 248-keV transition, and the spin of this isomer was reassigned from (11-) to (10-). The de-excitation of the (11-) isomeric level in 192Po by the 154-keV transition was confirmed and a parallel de-excitation by a 733-keV (E 3 ) transition to (8+) level of the ground-state band was suggested. Moreover, side feeding to the (4+) level of the ground-state band was proposed. The paper also discusses strengths of transitions de-exciting 11- isomers in neighboring Po and Pb isotopes.

  3. Electronic Structure Mediated Vibrational Coherence in Methyl Acetophenone Isomers

    NASA Astrophysics Data System (ADS)

    Konar, Arkaprabha; Shu, Yinan; Lozovoy, Vadim; Levine, Benjamin; Dantus, Marcos

    2014-05-01

    The role of ground and excited state electronic structures in influencing the vibrational coherences in gas phase polyatomic molecules has been a hot topic for quite some time. Here we explore the time resolved dynamics of acetophenone and its methyl substituted isomer when excited by intense 800nm femtosecond pump and probe pulses. The parent ion yield show 500 fs modulations that die down within 3ps. Similar modulations having the same timescales in the parent ion yield are also observed for the p-methyl isomer. The o-methyl isomer however shows longer 1ps modulations. Interestingly enough no oscillations are observed for the meta isomer. Quantum chemical calculations at the CASSCF/6-311G level of theory predicts that upon excitation the neutral ground state is planar and the energy spacing between the levels is very small. Preliminary calculations also predict torsional motion coupled to electronic modulations on the D0 state and further calculations are being performed to ascertain the involvement of the D1 and D2 states. This could help us better understand the electronic effect of substitution on a benzene ring.

  4. Electronic Structure Mediated Vibrational Coherence in Methyl Acetophenone Isomers

    NASA Astrophysics Data System (ADS)

    Konar, Arkaprabha; Shu, Yinan; Levine, Benjamin; Lozovoy, Vadim; Dantus, Marcos

    2014-03-01

    The role of ground and excited state electronic structures in influencing the vibrational coherences in gas phase polyatomic molecules has been a hot topic for quite some time. Here we explore the time resolved dynamics of acetophenone and its methyl substituted isomer when excited by intense 800nm femtosecond pump and probe pulses. The parent ion yield show 500 fs modulations that die down within 3ps. Similar modulations having the same timescales in the parent ion yield are also observed for the p-methyl isomer. The o-methyl isomer however shows longer 1ps modulations. Interestingly enough no oscillations are observed for the meta isomer. Quantum chemical calculations at the CASSCF/6-311G level of theory predicts that upon excitation the neutral ground state is planar and the energy spacing between the levels is very small. Preliminary calculations also predict torsional motion coupled to electronic modulations on the D0 state and further calculations are being performed to ascertain the involvement of the D1 and D2 states. This could help us better understand the electronic effect of substitution on a benzene ring.

  5. Identification of a shape isomer in 235U.

    PubMed

    Oberstedt, A; Oberstedt, S; Gawrys, M; Kornilov, N

    2007-07-27

    The shape isomer in 235U has been searched for in a neutron-induced fission experiment on 234U, which was performed at the isomer spectrometer NEPTUNE of the EC-JRC IRMM. A neutron source, with a tunable pulse frequency in the Hz to kHz range and its individually adjustable neutron pulse width in connection with an appropriate detector system turned out to be the ideal instrument to perform an isomer search, when decay half-lives above 100 micros are expected. From the delayed fission events observed for two different NEPTUNE settings and at mean incident neutron energies En=0.95 and 1.27 MeV the isomeric fission half-life could be determined to be T1/2=(3.6+/-1.8) ms. The corresponding cross section was determined to sigmaif=(10+/-8) microb. With these results an experimental confirmation for the existence of a superdeformed shape isomer in odd-uranium isotopes is given for the first time. PMID:17678355

  6. Computational Docking of the Isomers of Nonylphenol to the Ligand Binding Domain of the Estrogen Receptor

    EPA Science Inventory

    Nonylphenols are environmentally persistent endocrine disrupting chemicals. They exist in the environment as complex mixtures containing many nonylphenol isomers. Environmental mixtures of nonylphenols, along with a few single isomers have been tested for their capacity to inte...

  7. FY2011 Annual Report for the Actinide Isomer Detection Project

    SciTech Connect

    Warren, Glen A.; Francy, Christopher J.; Ressler, Jennifer J.; Erikson, Luke E.; Tatishvili, Gocha; Hatarik, R.

    2011-10-01

    This project seeks to identify a new signature for actinide element detection in active interrogation. This technique works by exciting and identifying long-lived nuclear excited states (isomers) in the actinide isotopes and/or primary fission products. Observation of isomers in the fission products will provide a signature for fissile material. For the actinide isomers, the decay time and energy of the isomeric state is unique to a particular isotope, providing an unambiguous signature for SNM. This project entails isomer identification and characterization and neutron population studies. This document summarizes activities from its third year - completion of the isomer identification characterization experiments and initialization of the neutron population experiments. The population and decay of the isomeric state in 235U remain elusive, although a number of candidate gamma rays have been identified. In the course of the experiments, a number of fission fragment isomers were populated and measured [Ressler 2010]. The decays from these isomers may also provide a suitable signature for the presence of fissile material. Several measurements were conducted throughout this project. This report focuses on the results of an experiment conducted collaboratively by PNNL, LLNL and LBNL in December 2010 at LBNL. The measurement involved measuring the gamma-rays emitted from an HEU target when bombarded with 11 MeV neutrons. This report discussed the analysis and resulting conclusions from those measurements. There was one strong candidate, at 1204 keV, of an isomeric signature of 235U. The half-life of the state is estimated to be 9.3 {mu}s. The measured time dependence fits the decay time structure very well. Other possible explanations for the 1204-keV state were investigated, but they could not explain the gamma ray. Unfortunately, the relatively limited statistics of the measurement limit, and the lack of understanding of some of the systematic of the experiment, limit

  8. Vibronic Spectroscopy of a Structural Isomer of Quinoline: -

    NASA Astrophysics Data System (ADS)

    Mehta-Hurt, Deepali N.; Korn, Joseph A.; Zwier, Timothy S.

    2013-06-01

    This talk will present results of a gas phase, jet-cooled vibronic spectroscopy study of (Z)-phenylvinylnitrile ((Z)-C_6H_5-CH=CH-C=N, (Z)-PVN). With a substituent locked into a cis conformation with respect to the aromatic ring, (Z)-PVN is postulated to be a molecule with an ideal functionality to isomerize to quinoline upon photoexcitation. As such, (Z)-PVN is particularly relevant to Titan's nitrile-containing atmosphere, where much of the chemistry is photochemically driven. As a first step towards such photochemical studies, a fluorescence excitation spectrum of a mixture of (E)- and (Z)-PVN was collected spanning the range 33,300-35,580 cm^{-1} (300.0-281.0 nm). Previous investigations in the Zwier group pertaining to the vibronic spectroscopy of (E)-PVN allowed for the identification of peaks in the (E)- and (Z)-PVN composite spectrum that were solely due to (Z)-PVN, and the S_0-S_1 origin of (Z)-PVN was identified as a dominant band that occurs at 33,706 cm^{-1}. For additional confirmation, ultraviolet depletion spectroscopy (UVD) was used to obtain an isomer specific spectrum of (Z)-PVN as well as search for non-radiative transitions. Dispersed fluorescence spectra that characterize the vibronic activity have also been acquired. A comparison between the vibronic spectroscopy of (Z)-PVN with both (E)-PVN and (Z)-phenylvinylacetylene ((Z)-PVA), the hydrocarbon analog of (Z)-PVN, will be made in this talk.

  9. Precursor anion states in dissociative electron attachment to chlorophenol isomers.

    PubMed

    Kossoski, F; Varella, M T do N

    2016-07-28

    We report a theoretical study on low-energy (<10 eV) elastic electron scattering from chlorophenol isomers, namely, para-chlorophenol (pCP), meta-chlorophenol (mCP), and ortho-chlorophenol (oCP). The calculations were performed with the Schwinger multichannel method with pseudopotentials, and analysis of the computed integral cross sections and virtual orbitals revealed one σCCl (∗), one σOH (∗), and three π(∗) shape resonances. We show that electron capture into the two lower lying π(∗) orbitals initiates dissociative processes that lead to the elimination of the chloride ion, accounting for the two overlapping peaks where this fragment was observed. Despite the relatively small differences on the energetics of the π(∗) resonances, a major isomeric effect was found on their corresponding autodetachment lifetimes, which accounts for the observed increasing cross sections in the progression pCP < mCP < oCP. In particular, dissociation from the π1 (∗) anion of pCP is largely suppressed because of the unfavorable mixing with the σCCl (∗) state. We found the intramolecular hydrogen bond present in oCP to have the opposite effects of stabilizing the σCCl (∗) resonance and destabilizing the σOH (∗) resonance. We also suggest that the hydrogen abstraction observed in chlorophenols and phenol actually takes place by a mechanism in which the incoming electron is directly attached to the dissociative σOH (∗) orbital. PMID:27475364

  10. Production of long-lived hafnium isomers in reactor irradiations

    NASA Astrophysics Data System (ADS)

    Karamian, S. A.; Carroll, J. J.; Adam, J.; Kulagin, E. N.; Shabalin, E. P.

    2006-06-01

    Experiments on production of long-lived Hf178m isomer in reactor irradiations are described. Properties of this nuclide are promising for its potential application as a relatively safe power source characterized by high density of accumulated energy. Metal natHf samples were activated in the Dubna IBR-2 reactor at positions corresponding to different neutron fluxes. Samples were bare or shielded by Cd and B 4C layers. The gamma activity of the samples was analyzed with Ge gamma spectrometers during a two-year period following their irradiation. In the presence of dominant activation products 175Hf and 181Hf, the high-spin isomers Hf178m and Hf179m were also detected despite relatively low levels. The isomer-to-ground state ratios and cross-sections were determined from the measured yields. For Hf178m, the cross-section for burnup (destruction) by neutron capture after its production was also estimated, clarifying the results from earlier experiments. In the context of suggestions for use of Hf178m for applications, the results confirm that large-scale production of this isomer by reactor irradiations is not feasible. In contrast, the efficiency of production of Hf179m is much higher and an amount of about 10 16 atoms may be produced in standard reactor irradiations. For Hf178m, more productive methods are known, in particular fast neutron irradiations at E n ≥ 14 MeV and spallation reactions at intermediate energies. Neutron cross-sections for isomers may also be significant in astrophysics.

  11. Oleanolic Acid, a Compound Present in Grapes and Olives, Protects against Genotoxicity in Human Mammary Epithelial Cells.

    PubMed

    Sánchez-Quesada, Cristina; López-Biedma, Alicia; Gaforio, José J

    2015-01-01

    Oleanolic acid (AO) and maslinic acid (MA) are constituents of the skins of different fruits, including olives and white or red grapes. Although both compounds are known to have beneficial properties against different types of cancers, thus far, there are no studies about their chemopreventive effects in human breast cancer. Thus, we sought to elucidate whether both compounds possess chemopreventive activity. Two cell lines of human breast cancer cells and one noncancerous human mammary epithelial cells were used to determine the effects of OA and MA. The results showed that OA inhibited the proliferation and increased the oxidative stress of highly invasive cells. Additionally, OA decreased oxidative stress and oxidative damage to the DNA in human mammary epithelial cells. These results suggest that OA could act as a chemopreventive agent in human breast cancer and could inhibit the proliferation of highly invasive breast cancer cells. PMID:26225949

  12. Present and future of lead/acid battery manufacturer in the Commonwealth of Independent States (formerly the USSR)

    NASA Astrophysics Data System (ADS)

    Rusin, A. I.; Leonov, V. N.; Gerasimov, A. G.; Volinkin, V. T.

    The production of lead/acid batteries in the former USSR, and now in the CIS, is concentrated in eight manufacturing plants (seven in Russia, one in Kazakhstan). The batteries that are manufactured include: automotive, aircraft, stationary, traction, diesel locomotive, railway car, boat, motorcycle, low-capacity sealed, and submersible designs. These activities involve the annual processing of 230 000 tonnes of lead. A brief review is given of the technology used in each of the battery designs.

  13. Isomer-specific biodegradation of nonylphenol in an activated sludge bioreactor and structure-biodegradability relationship.

    PubMed

    Lu, Zhijiang; Reif, Rubén; Gan, Jay

    2015-01-01

    Nonylphenol (NP), one of the priority hazardous substances, is in fact a mixture of numerous isomers. It is inconclusive whether or not biodegradation during wastewater treatment process is isomer-specific, leading to the environmental release of NP in different isomer profiles. In this study, we evaluated the isomer selectivity of 19 NP isomers in a laboratory-scale continuous flow conventional activated sludge bioreactor under various operational conditions. The removal efficiency of NP isomers ranged from 90 to 99%, depending on the operational conditions and isomer structures. Isomer selective biodegradation resulted in the increase of composition of recalcitrant isomers, such as, NP₁₉₃a/b, NP₁₁₀a and NP₁₉₄ in the effluent. Moreover, biodegradability was related to the bulkiness of α-substituents and followed α-dimethyl > α-ethyl-α-methyl > α-methyl-α-n-propyl > α-iso-propyl-α-methyl. Steric effect index, a quantitative descriptor of steric hindrance, was linearly correlated with residues of NP isomers in the effluent (R² = 0.76). Decrease of temperature to 10 °C decreased the overall biodegradability and also enhanced the relative enrichment of recalcitrant isomers. These findings suggest that isomer compositions of NP entering the environment may be different from those in technical mixtures and that isomeric selectivity should be taken into account to better understand the occurrence, fate, and ecological risks of NP. PMID:25462736

  14. 40 CFR 180.418 - Cypermethrin and an isomer zeta-cypermethrin; tolerances for residues.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Cypermethrin and an isomer zeta... FOOD Specific Tolerances § 180.418 Cypermethrin and an isomer zeta-cypermethrin; tolerances for... (±))(cis-trans 3-(2,2-dichloroethenyl)-2,2 dimethylcyclopropanecarboxylate and its inactive R-isomers in...

  15. 40 CFR 180.418 - Cypermethrin and an isomer zeta-cypermethrin; tolerances for residues.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 25 2012-07-01 2012-07-01 false Cypermethrin and an isomer zeta... FOOD Specific Tolerances § 180.418 Cypermethrin and an isomer zeta-cypermethrin; tolerances for... (±))(cis-trans 3-(2,2-dichloroethenyl)-2,2 dimethylcyclopropanecarboxylate and its inactive R-isomers in...

  16. 40 CFR 721.10564 - Mixed amino diaryl sulfone isomers (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Mixed amino diaryl sulfone isomers... Specific Chemical Substances § 721.10564 Mixed amino diaryl sulfone isomers (generic). (a) Chemical... as mixed amino diaryl sulfone isomers (PMN P-08-39) is subject to reporting under this section...

  17. 40 CFR 721.10564 - Mixed amino diaryl sulfone isomers (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Mixed amino diaryl sulfone isomers... Specific Chemical Substances § 721.10564 Mixed amino diaryl sulfone isomers (generic). (a) Chemical... as mixed amino diaryl sulfone isomers (PMN P-08-39) is subject to reporting under this section...

  18. 40 CFR 180.418 - Cypermethrin and an isomer zeta-cypermethrin; tolerances for residues.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Cypermethrin and an isomer zeta... FOOD Specific Tolerances § 180.418 Cypermethrin and an isomer zeta-cypermethrin; tolerances for... (±))(cis-trans 3-(2,2-dichloroethenyl)-2,2 dimethylcyclopropanecarboxylate and its inactive R-isomers in...

  19. Syntheses of the sulfoconjugated isomers of norepinephrine and dopamine, controlled by HPLC with ultraviolet detection.

    PubMed

    Strobel, G; Werle, E; Helfinger, H; Griebel, D; Weicker, H

    1988-09-15

    The physiological significance of sulfoconjugated catecholamines and their involvement in clinical disorders, e.g. hypertension and Parkinsonism, is poorly investigated. For this reason, the sulfoconjugated isomers of dopamine as well as of norepinephrine were synthesized by modified methods. All isomers and their intermediates could be detected by a reversed-phase high-performance liquid chromatography with ultraviolet detection (HPLC-UV) with short retention times and a good reproducibility. Ion-exchange chromatography with an extended column length improved the separation of the reaction products, and the immediate control by HPLC-UV enabled precise cutting of the fractions. The selection of the fractions with the optimum ratios of product/by-product resulted in improved yields and highest purity. All by-products, e.g. dopamine sulfonic acids, were less than 0.04%, as detected by HPLC-UV and, in addition, the contamination by free catecholamines was only 41 x 10(-4)-87 x 10(-4)%, as measured by HPLC with electrochemical detection (HPLC-ED). The purity was further demonstrated in two highly sensitive biological assays: cAMP production in human mononuclear leukocytes and aggregation of human platelets. The sulfoconjugated catecholamines were characterized by melting point, thin-layer chromatography, infrared spectrum, HPLC-UV, elemental analysis, and unequivocally identified by 1H-NMR. PMID:3416878

  20. Olfaction Presentation System Using Odor Scanner and Odor-Emitting Apparatus Coupled with Chemical Capsules of Alginic Acid Polymer

    NASA Astrophysics Data System (ADS)

    Sakairi, Minoru; Nishimura, Ayako; Suzuki, Daisuke

    For the purpose of the application of odor to information technology, we have developed an odor-emitting apparatus coupled with chemical capsules made of alginic acid polymer. This apparatus consists of a chemical capsule cartridge including chemical capsules of odor ingredients, valves to control odor emission, and a temperature control unit. Different odors can be easily emitted by using the apparatus. We have developed an integrated system of vision, audio and olfactory information in which odor strength can be controlled coinciding with on-screen moving images based on analytical results from the odor scanner.

  1. Changes in PCDD/PCDF formation processes during instationary phases of combustor operation--exemplified by the use of Cl4DD isomer patterns.

    PubMed

    Neuer-Etscheidt, K; Orasche, J; Nordsieck, H; Streibel, T; Zimmermann, R; Kettrup, A

    2007-04-01

    In this paper results of various measurement campaigns at different municipal waste incineration (MWI) plants concerning the change of the PCDD/PCDF isomer distribution in the crude gas during transiently impaired combustion conditions are presented. The focus is on the Cl4DD isomer distributions exemplarily for all other homologue groups to demonstrate the change in PCDD/PCDF formation mechanism at transient combustion conditions. Additionally to crude gas samples, at one plant filter and boiler ash were investigated simultaneously to determine if there is any difference in the isomer distribution between the matrices. For the ash from an electrostatic precipitator (ESP ash), the boiler ash and the corresponding crude gas sample, nearly identical changes in the Cl4DD isomer distribution under transient combustion conditions in relation to the normal operation process could be detected. By comparing the Cl4DD isomer distributions from different incineration plants (two municipal waste incinerators and one little incinerator burning wood chips for heating domestic household) under transient combustion conditions, in all cases the 1,3,6,8- and 1,3,7,9-Cl4DD were dominating the isomer distribution, whereas under normal operation other isomers were predominant. Obviously PCDD/PCDF formation mechanisms under transient combustion conditions are independent from the type of incinerator and of the burned fuel, respectively. Data sets were analyzed with respect to the possible reaction mechanism via chlorophenols and a good correlation of 2,4,6-trichlorophenol during the second phase of a start-up process and during a CO experiment was found. To get more detailed information about possible formation mechanisms, at one plant the dependence of the PCDD/PCDF isomer distribution on the different matrices was studied. Separate analysis of fly ash collected at the boiler exit, subsequent gas phase, ESP ash and boiler ash under normal operation conditions showed that, apart from

  2. Calculated yield of isomer depletion due to NEEC for {sup 93m}Mo recoils

    SciTech Connect

    Karamian, S. A.; Carroll, J. J.

    2012-11-15

    In the present work, quantitative calculations were carried out for production and depletion of the {sup 93m}Mo isomer in a relatively simple experiment using {sup 91}Zr beam ions. Such studies could be arranged at existing and operating accelerator facilities, e.g. at GSI or in JINR. The {sup 93m}Mo nuclei produced in a He gas target due to the {sup 4}He({sup 91}Zr, 2n) reaction will recoil into a gas stopper with a high velocity, being then depleted due to NEEC in highly-ionized species.

  3. Positron emission tomographic investigations of central muscarinic cholinergic receptors with three isomers of [76Br]BrQNP.

    PubMed

    Strijckmans, V; Bottlaender, M; Luo, H; Ottaviani, M; McPherson, D W; Loc'h, C; Fuseau, C; Knapp, F F; Mazière, B

    1997-05-01

    We studied the potential of three radiobrominated isomers of BrQNP, (Z(-,-)-[76Br]BrQNP, E(-,-)-[76Br]BrQNP and E(-,+)-[76Br]BrQNP), as suitable radioligands for imaging of central muscarinic cholinergic receptors in the human brain. These radioligands were stereospecifically prepared by electrophilic radiobromodestannylation of the respective tributylstannyl precursors using no-carrier-added [76Br]BrNH4 and peracetic acid. Preliminary pharmacological characterizations were determined by biodistribution, autoradiography, competition, displacement and metabolite studies in rats. The (-,-)-configuration presented important specific uptakes in brain muscarinic cholinergic receptor (mAChR)-rich structures and in heart, low metabolization rates and an apparent M2 selectivity. The (-,+)-configuration revealed more rapid clearance, lower uptake, a higher metabolization rate and an apparent M1 selectivity. Reversibility of the binding was confirmed for the three radiotracers. Positron emission tomography in the living baboon brain revealed high and rapid uptake in the brain and accumulation in the mAChR-rich structures studied. At 30 min p.i., the E(-,-)-radiotracer reached a plateau in cortex, pons and thalamus with concentrations of 29%, 24% and 19% ID/l, respectively. Z(-,-)-[76Br]BrQNP also accumulated in these structures, reaching a maximal uptake (27% ID/l) in the cortex 2 h p.i. At 5 min p.i. a plateau (17% ID/l) was only observed in the cortex for the E(-, +)-[76Br]BrQNP; by contrast, the other structures showed slow washout. After 3 weeks, the (-,-)-radiotracers were studied in the same baboon pretreated with dexetimide (1 mg/kg), a well-known muscarinic antagonist. In all the mAChR structures, the highly reduced uptake observed after this preloading step indicates that these radiotracers specifically bind to muscarinic receptors. Z(-, -)-[76Br]BrQNP, which is displaced in higher amounts from M2 mAChR-enriched structures, reveals an M2 affinity. The two isomers

  4. Isomer-specific determination of 4-nonylphenols using comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry.

    PubMed

    Eganhouse, Robert P; Pontolillo, James; Gaines, Richard B; Frysinger, Glenn S; Gabriel, Frédéric L P; Kohler, Hans-Peter E; Giger, Walter; Barber, Larry B

    2009-12-15

    Technical nonylphenol (tNP), used for industrial production of nonylphenol polyethoxylate surfactants, is a complex mixture of C(3-10)-phenols. The major components, 4-nonylphenols, are weak endocrine disruptors whose estrogenicities vary according to the structure of the branched nonyl group. Thus, accurate risk assessment requires isomer-specific determination of 4-NPs. Comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC x GC/ToFMS) was used to characterize tNP samples obtained from seven commercial suppliers. Under optimal chromatographic conditions, 153-204 alkylphenol peaks, 59-66 of which were identified as 4-NPs, were detected. The 4-NPs comprised approximately 86-94% of tNP, with 2-NPs and decylphenols making up approximately 2-9% and approximately 2-5%, respectively. The tNP products were analyzed for eight synthetic 4-NP isomers, and results were compared with published data based on GC/MS analysis. Significant differences were found among the products and between two samples from a single supplier. The enhanced resolution of GC x GC coupled with fast mass spectral data acquisition by ToFMS facilitated identification of all major 4-NP isomers and a number of previously unrecognized components. Analysis of tNP altered by the bacterium, Sphingobium xenophagum Bayram, revealed several persistent 4-NPs whose structures and estrogenicities are presently unknown. The potential of this technology for isomer-specific determination of 4-NP isomers in environmental matrices is demonstrated using samples of wastewater-contaminated groundwater and municipal wastewater. PMID:19924899

  5. Isomer-specific determination of 4-nonylphenols using comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry

    USGS Publications Warehouse

    Eganhouse, R.P.; Pontolillo, J.; Gaines, R.B.; Frysinger, G.S.; Gabriel, F.L.P.; Kohler, H.-P.E.; Giger, W.; Barber, L.B.

    2009-01-01

    Technical nonylphenol (tNP), used for industrial production of nonylphenol polyethoxylate surfactants, is a complex mixture of C3-10-phenols. The major components, 4-nonylphenols, are weak endocrine disruptors whose estrogenicities vary according to the structure of the branched nonyl group. Thus, accurate risk assessment requires isomer-specific determination of 4-NPs. Comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC x GC/ ToFMS) was used to characterize tNP samples obtained from seven commercial suppliers. Under optimal chromatographic conditions, 153-204 alkylphenol peaks, 59-66 of which were identified as 4-NPs, were detected. The 4-NPs comprised ???86-94% of tNP, with 2-NPs and decylphenols making up???2-9%and???2-5%, respectively. The tNP products were analyzed for eight synthetic 4-NP isomers, and results were compared with published data based on GC/ MS analysis. Significant differences were found among the products and between two samples from a single supplier. The enhanced resolution of GC x GC coupled with fast mass spectral data acquisition by ToFMS facilitated identification of all major 4-NP isomers and a number of previously unrecognized components. Analysis of tNP altered by the bacterium, Sphingobium xenophagum Bayram, revealed several persistent 4-NPs whose structures and estrogenicities are presently unknown. The potential of this technology for isomer-specific determination of 4-NP isomers in environmental matrices is demonstrated using samples of wastewatercontaminated groundwater and municipal wastewater. ?? 2009 American Chemical Society.

  6. Cis and Trans Isomers of Cycloalkenes

    ERIC Educational Resources Information Center

    Barrows, Susan E.; Eberlein, Thomas H.

    2005-01-01

    A study investigates the strain in medium-sized cycloalkenes and the geometric and electronic distortions through which alkenes can relieve that strain. Literature data is summarized and results are presented with the aim of providing a concise reference for those interested in addressing the topic in an introductory organic chemistry curriculum.

  7. Distribution of Polyunsaturated Fatty Acids in Bacteria Present in Intestines of Deep-Sea Fish and Shallow-Sea Poikilothermic Animals

    PubMed Central

    Yano, Y.; Nakayama, A.; Yoshida, K.

    1997-01-01

    The lipid and fatty acid compositions in nine obligate and facultative barophilic bacteria isolated from the intestinal contents of seven deep-sea fish were determined. Phospholipid compositions were simple, with phosphatidylethanolamine and phosphatidylglycerol predominating in all strains. Docosahexaenoic acid (DHA; 22:6n-3), which has not been reported in procaryotes except for deep-sea bacteria, was found to be present in eight strains at a level of 8.1 to 21.5% of total fatty acids. In the other strain, eicosapentaenoic acid (EPA; 20:5n-3) was present at a level of 31.5% of total fatty acids. Other fatty acids observed in all strains were typical of marine gram-negative bacteria. Subcultures from pouches prepared from intestinal contents of five deep-sea fish by the most-probable-number (MPN) method were analyzed for fatty acids, and all subcultures contained DHA and/or EPA. Accordingly, viable cell counts of bacteria containing DHA and EPA were estimated at a maximum of 1.3 x 10(sup8) and 2.4 x 10(sup8) cells per ml, respectively, and accounted for 14 and 30%, respectively, of the total cell counts in the intestinal contents of the deep-sea fish. In the case of 10 shallow-sea poikilothermic animals having bacterial populations of 1.1 x 10(sup6) to 1.9 x 10(sup9) CFU per ml in intestinal contents, no DHA was found in the 112 isolates examined, while production of EPA was found in 40 isolates from cold- and temperate-sea samples. These results suggest that DHA and EPA are involved in some adaptations of bacteria to low temperature and high pressure. PMID:16535638

  8. Nalidixic Acid-Resistant Salmonella enterica Serotype Typhi Presenting as a Primary Psoas Abscess: Case Report and Review of the Literature

    PubMed Central

    Shakespeare, William A.; Davie, Daniel; Tonnerre, Claude; Rubin, Michael A.; Strong, Michael; Petti, Cathy A.

    2005-01-01

    We report an unusual case of Salmonella enterica serotype Typhi presenting as a primary psoas abscess. The isolate tested susceptible to ciprofloxacin but resistant to nalidixic acid in vitro, a pattern associated with fluoroquinolone therapeutic failures. We review the literature for serovar Typhi psoas abscess in the absence of bacteremia and discuss the importance of identifying isolates with reduced susceptibility to fluoroquinolones. PMID:15695728

  9. Influence on Levels of Information as Presented by Different Technologies on Students' Understanding of Acid, Base, and pH Concepts.

    ERIC Educational Resources Information Center

    Nakhleh, Mary B.; Krajcik, Joseph S.

    1994-01-01

    Involves secondary students in a study designed to allow investigation into how different levels of information presented by various technologies (chemical indicators, pH meters, and microcomputer-based laboratories-MBLs) affected students' understanding of acid, base, and pH concepts. Results showed that students using MBLs exhibited a greater…

  10. The origin and structures of dimeric fatty acids from the anaerobic reaction between soya-bean lipoxygenase, linoleic acid and its hydroperoxide

    PubMed Central

    Garssen, G. J.; Vliegenthart, J. F. G.; Boldingh, J.

    1972-01-01

    In an anaerobic system soya-bean lipoxygenase catalyses in the presence of linoleic acid and l-13-hydroperoxyoctadeca-cis-9-trans-11-dienoic acid the formation of dimeric fatty acids and of carbonyl compounds. The analogous reaction does not take place when d-9-hydroperoxyoctadeca-trans-10-cis-12-dienoic acid is used instead of the 13-hydroperoxy isomer. Non-oxygenated dimers stem directly from linoleic acid and have C(11)–C(13′) or –C(9′) and C(13)–C(13′) or –C(9′) linkages. Dimers that contain oxygen originate from linoleic acid and linoleic acid hydroperoxide. It is most likely that the oxygen is present in epoxy groups. PMID:4677139

  11. Spectroscopic Studies of the Several Isomers of UO3

    SciTech Connect

    Sweet, Lucas E.; Reilly, Dallas D.; Abrecht, David G.; Buck, Edgar C.; Meier, David E.; Su, Yin-Fong; Brauer, Carolyn S.; Schwantes, Jon M.; Tonkyn, Russell G.; Szecsody, James E.; Blake, Thomas A.; Johnson, Timothy J.

    2013-09-26

    Uranium trioxide is known to adopt seven different structural forms. While these structural forms have been well characterized using x-ray or neutron diffraction techniques, little work has been done to characterize their spectroscopic properties, particularly of the pure phases. Since the structural isomers of UO3 all have similar thermodynamic stabilities and most tend to hydrolyze under open atmospheric conditions, mixtures of UO3 phases and the hydrolysis products are common. Much effort went into isolating pure phases of UO3. Utilizing x-ray diffraction as a sample identification check, UV/Vis/NIR spectroscopic signatures of α-UO3, β-UO3, γ-UO3 and UO2(OH)2 products were obtained. The spectra of the pure phases can now be used to characterize typical samples of UO3, which are often mixtures of isomers.

  12. DNA interaction with cis- and trans- isomers of photosensitive surfactant

    NASA Astrophysics Data System (ADS)

    Unksov, I. N.; Kasyanenko, N. A.

    2014-12-01

    Interaction between DNA and photosensitive cationic surfactant in a solution is studied. Studies were conducted to examine the impact of the surfactant in its cis- conformation on the size of DNA molecule and also to investigate the phase behavior of the system depending on DNA and surfactant concentration. We conclude that trans- isomer of surfactant requires its smaller concentration to reach the DNA compaction compared with cis- isomer received by UV radiation of solutions. Studies of DNA-surfactant systems were performed by means of spectrophotometry and viscometry. Variation of surfactant concentration enables us to determine the precipitation zone on phase diagram. From the viscosity study it can be indicated that precipitation zone is narrower for UV-radiated surfactant and it shifts to higher surfactant concentration. Also we examine the reversibility of DNA compaction in systems with the surfactant in its trans- form.

  13. Density Functional Exploration of C4H3N Isomers.

    PubMed

    Custer, Thomas; Szczepaniak, Urszula; Gronowski, Marcin; Fabisiewicz, Emilia; Couturier-Tamburelli, Isabelle; Kołos, Robert

    2016-07-28

    Molecules having C4H3N stoichiometry are of astrophysical interest. Two of these, methylcyanoacetylene (CH3C3N) and its structural isomer allenyl cyanide (H2CCCHN), have been observed in interstellar space, while several more have been examined in laboratories. Here we describe, for a broad range of C4H3N isomers, density functional calculations (B3LYP/aug-cc-pVTZ) of molecular parameters including the energetics, geometries, rotational constants, electric dipole moments, polarizabilities, vibrational IR frequencies, IR absorption intensities, and Raman activities. Singlet-triplet splittings as well as singlet vertical electronic excitation energies are given for selected species. The identification of less stable C4H3N molecules, generated in ongoing spectroscopic experiments, relies heavily on these quantum chemical predictions. PMID:27341606

  14. The structural and dynamical variables of pentane isomers

    NASA Astrophysics Data System (ADS)

    Patel, Tarika K.; Vaghela, M. V.; Gajjar, P. N.

    2016-05-01

    We derived structural and dynamical properties of pentane isomers: normal pentane, iso-pentane and neo pentane for liquid and gaseous state. We use molecular dynamics simulation to calculate the dynamical properties of pentane isomers for number of particles 729 using the intermolecular potential and force due to Lenard Jones potential. The computations also include mean square displacement and self diffusion co-efficient using Einstein relation. In structural properties, structure factor and phonon frequency are obtaining from P Y Method and Hubbard and Beeby Approach respectively. The Intermolecular potential and self diffusion co-efficient depend on the branching in the structure. The pair correlation function and phonon dispersion curves revels the complex structure of neo-pentane with respect to iso-pentane and n-pentane.

  15. Characterization of geometric isomers of Norbornene end-capped imides

    NASA Technical Reports Server (NTRS)

    Young, P. R.; Chang, A. C.

    1983-01-01

    Three geometric isomers from the thermal isomerization of methylene-4,4' bis(endo-N-phenylbicyclo/2.2.1/hept-2-ene-5,6-di carboximide) (I) were chromatographically separated and isolated in order to investigate the thermal cure of norbornene end-capped imide oligomers, which display considerable promise for use in various aerospace adhesive and composite applications. Endo-endo (I), endo-exo (II), and exo-exo (III) configurations were assigned to each compound based on the results of NMR spectroscopy. Several chromatographic, spectroscopic, and thermal techniques were then used to characterize these three isomers which serve as model compounds for norbornene end-capped polyimides. It was found that each compound thermally isomerized to an equilibrium mixture of all three compounds prior to cure. It is proposed that these compounds react by different mechanisms in air and nitrogen.

  16. Magnesium lithospermate B and rosmarinic acid, two compounds present in Salvia miltiorrhiza, have potent antiviral activity against enterovirus 71 infections.

    PubMed

    Chung, Yi-Ching; Hsieh, Feng-Chia; Lin, Ying-Ju; Wu, Tzong-Yuan; Lin, Cheng-Wen; Lin, Ching-Ting; Tang, Nou-Ying; Jinn, Tzyy-Rong

    2015-05-15

    The aim of this study was to identify the active ingredients responsible for the anti-EV71 activity produced by Salvia miltiorrhiza extracts. A pGS-EV71 IRES-based bicistronic reporter assay platform was used for rapid analysis of compounds that could specifically inhibit EV71 viral IRES-mediated translation. The analysis identified 2 caffeic acid derivatives, magnesium lithospermate B (MLB) and rosmarinic acid (RA), which suppressed EV71 IRES-mediated translation at concentrations of 30μg/ml. We also found that MLB and RA inhibited EV71 infection when they were added to RD cells during the viral absorption stage. MLB had a low IC50 value of 0.09mM and a high TI value of 10.52. In contrast, RA had an IC50 value of 0.50mM with a TI value of 2.97. MLB and RA (100µg/ml) also reduced EV71 viral particle production and significantly decreased VP1 protein production. We propose that these two derivatives inhibit EV71 viral entry into cells and viral IRES activity, thereby reducing viral particle production and viral RNA expression and blocking viral VP1 protein translation. This study provides useful information for the development of anti-EV71 assays and reagents by demonstrating a convenient EV71 IRES-based bicistronic assay platform to screen for anti-EV71 IRES activity, and also reports 2 compounds, MLB and RA, which are responsible for the anti-EV71 activity of S. miltiorrhiza. PMID:25773498

  17. Condensations of single DNA molecules induced by heptaplatin and its chiral isomer

    SciTech Connect

    Zhang, Hong-Yan; Liu, Yu-Ru; Li, Wei; Li, Hui; Dou, Shuo-Xing; Xie, Ping; Wang, Wei-Chi; Wang, Peng-Ye

    2014-08-15

    Heptaplatin is a third-generation platinum antitumor drug. It has a chiral isomer. We studied the interactions between the two isomers and DNA by using magnetic tweezers and atomic force microscopy (AFM) to investigate the effect of chiralities of the isomers on the interactions. We found that the extension curves and average condensation rates of DNA molecules incubated with heptaplatin were nearly the same as those incubated with its chiral isomer. In addition, the structures of DNA molecules incubated with heptaplatin were also similar to those incubated with its chiral isomer. These results indicate the difference in chirality of the two isomers does not induce different interactions of the isomers with DNA. Our study may facilitate the understanding of interactions of platinum complexes with DNA and the design of new antitumor platinum complexes.

  18. In vitro human metabolism of permethrin isomers alone or as a mixture and the formation of the major metabolites in cryopreserved primary hepatocytes.

    PubMed

    Willemin, M-E; Kadar, A; de Sousa, G; Leclerc, E; Rahmani, R; Brochot, C

    2015-06-01

    In vitro metabolism of permethrin, a pyrethroid insecticide, was assessed in primary human hepatocytes. In vitro kinetic experiments were performed to estimate the Michaelis-Menten parameters and the clearances or formation rates of the permethrin isomers (cis- and trans-) and three metabolites, cis- and trans-3-(2,2 dichlorovinyl)-2,2-dimethyl-(1-cyclopropane) carboxylic acid (cis- and trans-DCCA) and 3-phenoxybenzoic acid (3-PBA). Non-specific binding and the activity of the enzymes involved in permethrin's metabolism (cytochromes P450 and carboxylesterases) were quantified. Trans-permethrin was cleared more rapidly than cis-permethrin with a 2.6-factor (25.7±0.6 and 10.1±0.3 μL/min/10(6) cells respectively). A 3-factor was observed between the formation rates of DCCA and 3-PBA obtained from trans- and cis-permethrin. For both isomers, the rate of formation of DCCA was higher than the one of 3-PBA. The metabolism of the isomers in mixture was also quantified. The co-incubation of isomers at different ratios showed the low inhibitory potential of cis- and trans-permethrin on each other. The estimates of the clearances and the formation rates in the co-incubation condition did not differ from the estimates obtained with a separate incubation. These metabolic parameters may be integrated in physiologically based pharmacokinetic (PBPK) models to predict the fate of permethrin and metabolites in the human body. PMID:25765475

  19. HPLC separation and FT-IR isomer differentiation of the 1,2,4,7/1,2,4,8-tetrachlorodibenzodioxin isomer pair: A theoretical/empirical approach to dibenzodioxin isomer assignmentt

    SciTech Connect

    Grainger, J.; Barnhart, E.; Patterson D.G. Jr.; Presser, D.

    1988-02-01

    The 1,2,4,7-and 1,2,4,8-tetrachlorodibenzodioxin (TCDD) isomers were separated by reversed-phase high-performance liquid chromatography (HPLC) with the use of a pyrene column. Fourier transform infrared (FT-IR) matrix isolation and vapor-phase spectra of the individual isomers were recorded. The spectra of the HPLC-seprated isomers correlate well with spectral subtraction results and were found to be distinct in three spectral regions: one of which allows for isomer structural assignment. Ambiguities and differences in published TCDD isomer FT-IR assignments are discussed in terms of a qualitative valence-bond approach and empirically derived estimates of ether linkage asymmetric stretching frequencies.

  20. Nuclear States with Abnormally Large Radii (size Isomers)

    NASA Astrophysics Data System (ADS)

    Ogloblin, A. A.; Demyanova, A. S.; Danilov, A. N.; Belyaeva, T. L.; Goncharov, S. A.

    2015-06-01

    Application of the methods of measuring the radii of the short-lived excited states (Modified diffraction model MDM, Inelastic nuclear rainbow scattering method INRS, Asymptotic normalization coefficients method ANC) to the analysis of some nuclear reactions provide evidence of existing in 9Be, 11B, 12C, 13C the excited states whose radii exceed those of the corresponding ground states by ~ 30%. Two types of structure of these "size isomers" were identified: neutron halo an α-clusters.

  1. Flame Propagation of Butanol Isomers/Air Mixtures

    SciTech Connect

    Veloo, Peter S.; Egolfopoulos, Fokion N.

    2011-01-01

    An experimental and computational study was conducted on the propagation of flames of saturated butanol isomers. The experiments were performed in the counterflow configuration under atmospheric pressure, unburned mixture temperature of 343 K, and for a wide range of equivalence ratios. The experiments were simulated using a recent kinetic model for the four isomers of butanol. Results indicate that n-butanol/air flames propagate somewhat faster than both sec-butanol/air and iso-butanol/air flames, and that tert-butanol/air flames propagate notably slower compared to the other three isomers. Reaction path analysis of tert-butanol/air flames revealed that iso-butene is a major intermediate, which subsequently reacts to form the resonantly stable iso-butenyl radical retarding thus the overall reactivity of tert-butanol/air flames relatively to the other three isomers. Through sensitivity analysis, it was determined that the mass burning rates of sec-butanol/air and iso-butanol/air flames are sensitive largely to hydrogen, carbon monoxide, and C{sub 1}–C{sub 2} hydrocarbon kinetics and not to fuel-specific reactions similarly to n-butanol/air flames. However, for tert-butanol/air flames notable sensitivity to fuel-specific reactions exists. While the numerical results predicted closely the experimental data for n-butanol/air and sec-butanol/air flames, they overpredicted and underpredicted the laminar flame speeds for iso-butanol/air and tert-butanol/air flames respectively. It was demonstrated further that the underprediction of the laminar flame speeds of tert-butanol/air flames by the model was most likely due to deficiencies of the C{sub 4}-alkene kinetics.

  2. Perfluorinated carboxylic acids in directly fluorinated high-density polyethylene material.

    PubMed

    Rand, Amy A; Mabury, Scott A

    2011-10-01

    Perfluorinated carboxylic acids (PFCAs) are ubiquitous in the environment and have been detected in human blood worldwide. One potential route is direct exposure to PFCAs through contact with polymers that have been fluorinated through a process referred to as direct fluorination. PFCAs are hypothesized to be reaction byproducts of direct fluorination when trace amounts of oxygen are present. The objective of this research was to investigate whether PFCAs could be measured in directly fluorinated high-density polyethylene (HDPE) bottles. PFCAs were quantified using Soxhlet extraction with methanol, followed by LC-MS/MS analysis. Total concentrations of PFCAs ranged from 8.5 ± 0.53 to 113 ± 2.5 ng/bottle (1 L), with the short-chain PFCAs, perfluoropropanoic, perfluorobutanoic, perfluoropentanoic, and perfluorohexanoic acids, being the dominant congeners observed. Relative PFCA concentrations varied depending on fluorination level. Structural isomers were detected using (19)F NMR and are hypothesized to have formed during the fluorination process; NMR data revealed the linear isomer typically comprised 55% of the examined sample. Internally branched, isopropyl branched, and t-butyl PFCA isomers of varying chain length were also identified. Electrochemical fluorination was previously thought to be the only source of branched PFCA isomers. The observation here of branched isomers suggests direct fluorination may be an additional source of exposure to these chemicals. The purpose of this study was to measure PFCAs in directly fluorinated material, serving as a previously unidentified source contributing to the environmental load of PFCAs, with potential for human exposure. PMID:21688793

  3. Determination of nonylphenol isomers in landfill leachate and municipal wastewater using steam distillation extraction coupled with comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry

    USGS Publications Warehouse

    Zhang, Caixiang; Eganhouse, Robert P.; Pontolillo, James; Cozzarelli, Isabelle M.; Wang, Yanxin

    2012-01-01

    4-Nonylphenols (4-NPs) are known endocrine disruptors and by-products of the microbial degradation of nonylphenol polyethoxylate surfactants. One of the challenges to understanding the toxic effects of nonylphenols is the large number of isomers that may exist in environmental samples. In order to attribute toxic effects to specific compounds, a method is needed for the separation and quantitation of individual nonylphenol isomers. The pre-concentration methods of solvent sublimation, solid-phase extraction or liquid–liquid extraction prior to chromatographic analysis can be problematic because of co-extraction of thousands of compounds typically found in complex matrices such as municipal wastewater or landfill leachate. In the present study, steam distillation extraction (SDE) was found to be an effective pre-concentration method for extraction of 4-NPs from leachate and wastewater, and comprehensive two-dimensional gas chromatography (GC × GC) coupled with fast mass spectral data acquisition by time-of-flight mass spectrometry (ToFMS) enhanced the resolution and identification of 4-NP isomers. Concentrations of eight 4-NP isomers were determined in leachate from landfill cells of different age and wastewater influent and effluent samples. 4-NP isomers were about 3 times more abundant in leachate from the younger cell than the older one, whereas concentrations in wastewater effluent were either below detection limits or <1% of influent concentrations. 4-NP isomer distribution patterns were found to have been altered following release to the environment. This is believed to reflect isomer-specific degradation and accumulation of 4-NPs in the aquatic environment.

  4. Analysis of the isomer ratios of polymethylated-DOTA complexes and the implications on protein structural studies.

    PubMed

    Opina, Ana Christina L; Strickland, Madeleine; Lee, Yong-Sok; Tjandra, Nico; Andrew Byrd, R; Swenson, Rolf E; Vasalatiy, Olga

    2016-03-21

    A rigidified and symmetrical polymethylated 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) ligand bearing four SSSS methyl groups in both the tetraaza ring and the acetate arms (SSSS-SSSS-M4DOTMA) was prepared. The isomer ratio of SSSS-SSSS-M4DOTMA complexed with a series of lanthanide ions was carefully investigated using RP-HPLC and NMR. A square antiprismatic (SAP) configuration was exclusively observed for the early lanthanides, while the twisted square antiprismatic (TSAP) geometry was preferred as the lanthanide ion size decreases. The late lanthanides preferentially adopted the TSAP geometry. One of the pendant arms was modified with a pyridyl disulfide group (SSSS-SSSS-M8SPy) for cysteine attachment and displayed a similar isomer trend as the parent compound, Ln-SSSS-SSSS-M4DOTMA. Covalent attachment to the ubiquitin S57C mutant showed resonances whose intensities are in agreement with the isomeric population observed by RP-HPLC. Furthermore, the NOE experiments combined with quantum chemical calculations have unequivocally demonstrated that the SAP of Pr-SSSS-SSSS-M4DOTMA and Pr-SSSS-SSSS-M8SPy, as well as the TSAP of Yb-SSSS-SSSS-M8SPy are more stable than their corresponding isomers. PMID:26857249

  5. Analysis of the isomer ratios of polymethylated-DOTA complexes and the implications on protein structural studies

    PubMed Central

    Opina, Ana Christina L.; Strickland, Madeleine; Lee, Yong-Sok; Tjandra, Nico; Byrd, R. Andrew; Swenson, Rolf E.; Vasalatiy, Olga

    2016-01-01

    A rigidified and symmetrical polymethylated 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) ligand bearing four SSSS methyl groups in both the tetraaza ring and the acetate arms (SSSS-SSSS-M4DOTMA) was prepared. The isomer ratio of SSSS-SSSS-M4DOTMA complexed with a series of lanthanide ions was carefully investigated using RP-HPLC and NMR. A square antiprismatic (SAP) configuration was exclusively observed for the early lanthanides, while the twisted square antiprismatic (TSAP) geometry was preferred as the lanthanide ion size decreases. The late lanthanides preferentially adopted the TSAP geometry. One of the pendant arms was modified with a pyridyl disulfide group (SSSS-SSSS-M8SPy) for cysteine attachment and displayed a similar isomer trend as the parent compound, Ln-SSSS-SSSS-M4DOTMA. Covalent attachment to the ubiquitin S57C mutant showed resonances whose intensities are in agreement with the isomeric population observed by HPLC. Furthermore, the NOE experiments combined with quantum chemical calculations have unequivocally demonstrated that the SAP of Pr-SSSS-SSSS-M4DOTMA and Pr-SSSS-SSSS-M8SPy, as well as the TSAP of Yb-SSSS-SSSS-M8SPy are more stable than their corresponding isomers. PMID:26857249

  6. Determination of the ^229Th isomer half-life

    NASA Astrophysics Data System (ADS)

    Burke, Jason; Beck, Bret; Becker, John; Haydell, Michael; Norman, Rick; Scielzo, Nicholas; Sheets, Steven; Swanberg, Erik

    2009-10-01

    Recently there has been renewed interest in studying the nuclear properties of the ^229Th isomer. ^229Th has the lowest known isomer at 7.6 eV [1]. Direct laser manipulation of the ground and first excited states could lead to the realization of the world's first nuclear clock. To understand the linewidth of the isomeric state we are conducting experiments to directly observe the half-life of the isomer decay. We use a novel ``hot-atom'' technique in which we catch the recoiling ^229Th nuclei following the alpha decay of ^233U -> ^229Th + α. On average 2% of the ^229Th populate the isomeric 3/2+ state compared to the 5/2+ ground state. Recoils are collected on various catcher plate materials, rotated in vacuum in front of an einzel lense and multi-channel plate detector. The internal conversion electrons are counted as a function of time to determine the half-life. Varying the catcher plate material we can investigate the effect that the materials have on the half-life. Determination of the half-life we will provide valuable guidance to Th trapping research [2]. 1) Beck et al., PRL 98, 142501 (2007) 2) Campbell et al., PRL 102, 233004 (2009) This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  7. Distinct carbon isotope fractionation during anaerobic degradation of dichlorobenzene isomers.

    PubMed

    Liang, Xiaoming; Mundle, Scott O C; Nelson, Jennifer L; Passeport, Elodie; Chan, Calvin C H; Lacrampe-Couloume, Georges; Zinder, Stephen H; Sherwood Lollar, Barbara

    2014-05-01

    Chlorinated benzenes are ubiquitous organic contaminants found in groundwater and soils. Compound specific isotope analysis (CSIA) has been increasingly used to assess natural attenuation of chlorinated contaminants, in which anaerobic reductive dechlorination plays an essential role. In this work, carbon isotope fractionation of the three dichlorobenzene (DCB) isomers was investigated during anaerobic reductive dehalogenation in methanogenic laboratory microcosms. Large isotope fractionation of 1,3-DCB and 1,4-DCB was observed while only a small isotope effect occurred for 1,2-DCB. Bulk enrichment factors (εbulk) were determined from a Rayleigh model: -0.8 ± 0.1 ‰ for 1,2-DCB, -5.4 ± 0.4 ‰ for 1,3-DCB, and -6.3 ± 0.2 ‰ for 1,4-DCB. εbulk values were converted to apparent kinetic isotope effects for carbon (AKIE) in order to characterize the carbon isotope effect at the reactive positions for the DCB isomers. AKIE values are 1.005 ± 0.001, 1.034 ± 0.003, and 1.039 ± 0.001 for 1,2-DCB, 1,3-DCB, and 1,4-DCB, respectively. The large difference in AKIE values between 1,2-DCB and 1,3-DCB (or 1,4-DCB) suggests distinct reaction pathways may be involved for different DCB isomers during microbial reductive dechlorination by the methanogenic cultures. PMID:24758692

  8. Six-quasiparticle isomer in {sup 140}Nd

    SciTech Connect

    Petrache, C. M.; Fantuzi, M.; Mengoni, D.; Petrache, D.; Bark, R. A.; Murray, S. T. H.; Lawrie, E. A.; Lawrie, J. J.; Mullins, S. M.; Lang, S.; Maliage, S. M.; Ramashidzha, T. M.; Ntshangase, S. S.; Ragnarsson, I.

    2006-09-15

    A search for isomeric states was performed in the nucleus {sub 60}{sup 140}Nd{sub 80} using in-beam {gamma}-ray spectroscopy and the {sup 126}Te({sup 18}O,4n) reaction. Prompt and delayed {gamma}-ray coincidences were measured with the AFRODITE spectrometer using the pulsed beam delivered by the Separated Sector Cyclotron of iThemba LABS. One new isomer was identified, with spin-parity I{sup {pi}}=20{sup +} and lifetime T{sub 1/2}{>=}400 ns, at an excitation energy E{sub x}=7430 keV. The lifetime of the 10{sup +} isomer at E{sub x}=3619 keV was determined to be 32.9(1.8) ns, confirming the previously reported value. The configuration of the I{sup {pi}}=20{sup +} isomer is assigned based on configuration-dependent cranked Nilsson-Strutinsky (CNS) calculations as a state {pi}(d{sub 5/2}g{sub 7/2}){sub 10{sup +}}{sup -4}x{nu}(h{sub 11/2}{sup -2}){sub 10{sup +}}, with the spin vectors of the six holes in the {sub 64}{sup 146}Gd{sub 82} core fully aligned.

  9. Oxidative Transformation of Aminodinitrotoluene Isomers by Multicomponent Dioxygenases

    PubMed Central

    Johnson, Glenn R.; Smets, Barth F.; Spain, Jim C.

    2001-01-01

    The electron-withdrawing nitro substituents of 2,4,6-trinitrotoluene (TNT) make the aromatic ring highly resistant to oxidative transformation. The typical biological transformation of TNT involves reduction of one or more of the nitro groups of the ring to produce the corresponding amine. Reduction of a single nitro substituent of TNT to an amino substituent increases the electron density of the aromatic nucleus considerably. The comparatively electron-dense nuclei of the aminodinitrotoluene (ADNT) isomers would be expected to be more susceptible to oxygenase attack than TNT. The hypothesis was tested by evaluating three nitroarene dioxygenases for the ability to hydroxylate the ADNT isomers. The predominant reaction was dioxygenation of the ring to yield nitrite and the corresponding aminomethylnitrocatechol. A secondary reaction was benzylic monooxygenation to form aminodinitrobenzyl alcohol. The substrate preferences and catalytic specificities of the three enzymes differed considerably. The discovery that the ADNT isomers are substrates for the nitroarene dioxygenases reveals the potential for extensive bacterial transformation of TNT under aerobic conditions. PMID:11722893

  10. Inner-shell and double ionization potentials of aminophenol isomers.

    SciTech Connect

    Kryzhevoi, N. V.; Santra, R.; Cederbaum, L. S.

    2011-01-01

    A comprehensive study of single and double core ionization potentials of the aminophenol molecule is reported. The role of relaxation, correlation, relativistic, and basis set effects in these potentials is clarified. Special attention is paid to the isomer dependence of the single and double core ionization potentials. Some of them are also compared with the respective values of the phenol and aniline molecules. It is shown that the core level single ionization potentials of the para-, meta-, and ortho-aminophenol molecules differ only slightly from each other, rendering these structural isomers challenging to distinguish for conventional x-ray photoelectron spectroscopy. In contrast, the energy needed to remove two core electrons from different atoms depends noticeably on the mutual arrangement and even on the relative orientations of the hydroxyl and amine groups. Together with the electrostatic repulsion between the two core holes, relaxation effects accompanying double core ionization play a crucial role here. The pronounced sensitivity of the double ionization potentials, therefore, enables a spectroscopic characterization of the electronic structure of aminophenol isomers by means of x-ray two-photon photoelectron spectroscopy.

  11. Cyclic Versus Linear Isomers Produced by Reaction of the Methylidyne Radical (CH) with Small Unsaturated Hydrocarbons

    SciTech Connect

    Goulay, Fabien; Trevitt, Adam J.; Meloni, Giovanni; Selby, Talitha M.; Osborn, David L.; Taatjes, Craig A.; Vereecken, Luc; Leone, Stephen R.

    2008-12-05

    The reactions of the methylidyne radical (CH) with ethylene, acetylene, allene, and methylacetylene are studied at room temperature using tunable vacuum ultraviolet (VUV) photoionization and time-resolved mass spectrometry. The CH radicals are prepared by 248 nm multiphoton photolysis of CHBr3 at 298 K and react with the selected hydrocarbon in a helium gas flow. Analysis of photoionization efficiency versus VUV photon wavelength permits isomer-specific detection of the reaction products and allows estimation of the reaction product branching ratios. The reactions proceed by either CH insertion or addition followed by H atom elimination from the intermediate adduct. In the CH + C2H4 reaction the C3H5 intermediate decays by H atom loss to yield 70(+-8)percent allene, 30(+-8)percent methylacetylene and less than 10percent cyclopropene, in agreement with previous RRKM results. In the CH + acetylene reaction, detection of mainly the cyclic C3H2 isomer is contrary to a previous RRKM calculation that predicted linear triplet propargylene to be 90percent of the total H-atom co-products. High-level CBS-APNO quantum calculations and RRKM calculation for the CH + C2H2 reaction presented in this manuscript predict a higher contribution of the cyclic C3H2 (27.0percent) versus triplet propargylene (63.5percent) than these earlier predictions. Extensive calculations on the C3H3 and C3H2D system combined with experimental isotope ratios for the CD + C2H2 reaction indicate that H-atom assisted isomerization in the present experiments is responsible for the discrepancy between the RRKM calculations and the experimental results. Cyclic isomers are also found to represent 30(+-6)percent of the detected products in the case of CH + methylacetylene, together with 33(+-6)percent 1,2,3-butatriene and 37(+-6)percent vinylacetylene. The CH + allene reaction gives 23(+-5)percent 1,2,3-butatriene and 77(+-5)percent vinylacetylene, whereas cyclic isomers are produced below the detection limit

  12. Feeding of the 1 1/2- isomers in stable Ir and Au isotopes

    SciTech Connect

    Fotiadis, Nikolaos; Nelson, Ronald O; Devlin, Matthew; Holloway, Shannon T; Kawano, Toshihiko; Talou, Patrick; Chadwick, Mark B; Becker, John A; Garrett, Paul E

    2008-01-01

    Excited states were studied and absolute partial {gamma}-ray cross sections were measured using the ({eta}, {eta}'{gamma}) reaction in {sup 191}Ir, {sup 193}Ir and {sup 197}Au. A Compton-suppressed germanium-detector array (GEANIE) for {gamma}-ray spectroscopy and the broad-spectrum pulsed neutron source of the Los Alamos Neutron Science Center's WNR facility were used for the measurement. The energy of the incident neutrons was determined using the time-of-flight technique. Absolute partial {gamma}-ray cross sections were measured up to incident neutron energy of 20 MeV for several transitions feeding directly the 1 1/2- isomers and ground states in {sup 191}Ir, {sup 193}Ir and {sup 197}Au. The feeding of the 1 1/2- isomers, which originate from the odd proton occupying the h{sub 1 1/2} orbital, was found for the three targets to be very similar and increasing relative to the feeding of the corresponding ground state with increasing neutron energy up to E{sub n} {approx} 10 MeV. Above this neutron energy the opening of the (n, 2{sub n}) reaction channel strongly affects the population of the isomers and leads to a decrease of their relative population compared to the population of the ground states. The experimental results are compared with theoretical predictions from the GNASH reaction model calculation implementing a version of the spin distribution for the pre-equilibrium reaction piece with either a compound nucleus spin distribution (CN-GNASH) or a Feshbach-Kerman-Koonin (FKK-GNASH) quantum mechanical spin distribution. The effects of the spin cutoff parameter values on the population of states are examined. Evidence is presented that FKK-GNASH provides a description of the experimental data that mitigates the need for adjustment of the level density parameter to fit the data.

  13. Clinical vampirism. A presentation of 3 cases and a re-evaluation of Haigh, the 'acid-bath murderer'.

    PubMed

    Hemphill, R E; Zabow, T

    1983-02-19

    Clinical vampirism is named after the mythical vampire, and is a recognizable, although rare, clinical entity characterized by periodic compulsive blood-drinking, affinity with the dead and uncertain identity. It is hypothetically the expression of an inherited archaic myth, the act of taking blood being a ritual that gives temporary relief. From ancient times vampirists have given substance to belief in the existence of supernatural vampires. Four vampirists, including Haigh, the 'acid-bath murderer', are described. From childhood they cut themselves, drank their own, exogenous human or animal blood to relieve a craving, dreamed of blood-shed, associated with the dead, and had a changing identity. They were intelligent, with no family mental or social pathology. Some self-cutters are auto-vampirists; females are not likely to assault others for blood, but males are potentially dangerous. Vampirism may be a cause of unpredictable repeated assault and murder, and should be looked for in violent criminals who are self-mutilators. No specific treatment is known. PMID:6823646

  14. Trace analysis of total naphthenic acids in aqueous environmental matrices by liquid chromatography/mass spectrometry-quadrupole time of flight mass spectrometry direct injection.

    PubMed

    Brunswick, Pamela; Shang, Dayue; van Aggelen, Graham; Hindle, Ralph; Hewitt, L Mark; Frank, Richard A; Haberl, Maxine; Kim, Marcus

    2015-07-31

    A rapid and sensitive liquid chromatography quadrupole time of flight method has been established for the determination of total naphthenic acid concentrations in aqueous samples. This is the first methodology that has been adopted for routine, high resolution, high throughput analysis of total naphthenic acids at trace levels in unprocessed samples. A calibration range from 0.02 to 1.0μgmL(-1) total Merichem naphthenic acids was validated and demonstrated excellent accuracy (97-111% recovery) and precision (1.9% RSD at 0.02μgmL(-1)). Quantitative validation was also demonstrated in a non-commercial oil sands process water (OSPW) acid extractable organics (AEOs) fraction containing a higher percentage of polycarboxylic acid isomers than the Merichem technical mix. The chromatographic method showed good calibration linearity of ≥0.999 RSQ to 0.005μgmL(-1) total naphthenic acids with a precision <3.1% RSD and a calculated detection limit of 0.0004μgmL(-1) employing Merichem technical mix reference material. The method is well suited to monitoring naturally occurring and industrially derived naphthenic acids (and other AEOs) present in surface and ground waters in the vicinity of mining developments. The advantage of the current method is its direct application to unprocessed environmental samples and to examine natural naphthenic acid isomer profiles. It is noted that where the isomer profile of samples differs from that of the reference material, results should be considered semi-quantitative due to the lack of matching isomer content. The fingerprint profile of naphthenic acids is known to be transitory during aging and the present method has the ability to adapt to monitoring of these changes in naphthenic acid content. The method's total ion scan approach allows for data previously collected to be examined retrospectively for specific analyte mass ions of interest. A list of potential naphthenic acid isomers that decrease in response with aging is proposed

  15. Relationship between Menthiafolic Acid and Wine Lactone in Wine.

    PubMed

    Giaccio, Joanne; Curtin, Chris D; Sefton, Mark A; Taylor, Dennis K

    2015-09-23

    Menthiafolic acid (6-hydroxy-2,6-dimethylocta-2,7-dienoic acid, 2a) was quantified by GC-MS in 28 white wines, 4 Shiraz wines, and for the first time in 6 white grape juice samples. Menthiafolic acid was detected in all but one of the wine samples at concentrations ranging from 26 to 342 μg/L and in the juice samples from 16 to 236 μg/L. Various model fermentation experiments showed that some menthiafolic acid in wine could be generated from the grape-derived menthiafolic acid glucose ester (2b) during alcoholic and malolactic fermentation. Samples containing high concentrations of menthiafolic acid were also analyzed by enantioselective GC-MS and were shown to contain this compound in predominantly the (S)-configuration. Enantioselective analysis of wine lactone (1) in one of these samples, a four-year-old Chardonnay wine showed, for the first time, the presence of the 3R,3aR,7aS isomer of wine lactone (1b), which is the enantiomer of the form previously reported as the sole isomer present in young wine samples. The weakly odorous 3R,3aR,7aS 1b form comprised 69% of the total wine lactone in the sample. On the basis of the enantioselectivity of the hydrolytic conversion of menthiafolic acid to wine lactone at pH 3.0 determined previously and the relative proportions of (R)- and (S)-menthiafolic acid in the Chardonnay wine, the predicted ratio of wine lactone enantiomers that would be formed from hydrolysis at ambient temperature of the menthiafolic acid present in this wine was close to the ratio measured, which was consistent with menthiafolic acid being the major or sole precursor to wine lactone in this sample. PMID:26321591

  16. Association between Human Plasma Chondroitin Sulfate Isomers and Carotid Atherosclerotic Plaques.

    PubMed

    Zinellu, Elisabetta; Lepedda, Antonio Junior; Cigliano, Antonio; Pisanu, Salvatore; Zinellu, Angelo; Carru, Ciriaco; Bacciu, Pietro Paolo; Piredda, Franco; Guarino, Anna; Spirito, Rita; Formato, Marilena

    2012-01-01

    Several studies have evidenced variations in plasma glycosaminoglycans content in physiological and pathological conditions. In normal human plasma GAGs are present mainly as undersulfated chondroitin sulfate (CS). The aim of the present study was to evaluate possible correlations between plasma CS level/structure and the presence/typology of carotid atherosclerotic lesion. Plasma CS was purified from 46 control subjects and 47 patients undergoing carotid endarterectomy showing either a soft or a hard plaque. The concentration and structural characteristics of plasma CS were assessed by capillary electrophoresis of constituent unsaturated fluorophore-labeled disaccharides. Results showed that the concentration of total CS isomers was increased by 21.4% (P < 0.01) in plasma of patients, due to a significant increase of undersulfated CS. Consequently, in patients the plasma CS charge density was significantly reduced with respect to that of controls. After sorting for plaque typology, we found that patients with soft plaques and those with hard ones differently contribute to the observed changes. In plasma from patients with soft plaques, the increase in CS content was not associated with modifications of its sulfation pattern. On the contrary, the presence of hard plaques was associated with CS sulfation pattern modifications in presence of quite normal total CS isomers levels. These results suggest that the plasma CS content and structure could be related to the presence and the typology of atherosclerotic plaque and could provide a useful diagnostic tool, as well as information on the molecular mechanisms responsible for plaque instability. PMID:22216412

  17. Stereospecificity of amino acid hydroxamate inhibition of aminopeptidases.

    PubMed

    Wilkes, S H; Prescott, J M

    1983-11-25

    Hydroxamates of amino acids and aliphatic acids are effective inhibitors of Aeromonas proteolytica amino-peptidase (EC 3.4.11.10) and of both the cytosolic (EC 3.4.11.1) and microsomal (EC 3.4.11.2) aminopeptidases of swine kidney. Cytosolic leucine aminopeptidase and the Aeromonas enzyme were inhibited to a greater extent by D isomers than by the L enantiomorphs, manganese-activated kidney cytosolic leucine aminopeptidase being inhibited 10 times more effectively by D-leucine and D-valine hydroxamic acids than by the L isomers. The D isomers of these two compounds inhibited Aeromonas aminopeptidase to an even greater extent with Ki values of 2 X 10(-9) and 5 X 10(-9), respectively, whereas the corresponding L isomers were bound 150 times less tightly. With the Aeromonas enzyme, a comparison of inhibition by racemic mixtures with that of the corresponding L isomers indicated that in all cases the contribution of the D isomer was predominant. Isocaproic hydroxamic acid inhibited this enzyme equally well as L-leucine hydroxamic acid, indicating that the amino group orientation in the D isomer contributes to the binding efficacy. Swine kidney microsomal aminopeptidase was also inhibited by D isomers of leucine and valine hydroxamic acids but in contrast to the other two enzymes, the inhibition was 10-fold less than that observed for the corresponding L isomers. Cytosolic leucine aminopeptidase with either 6 g atoms of zinc per mol or 12 g atoms of zinc per mol was inhibited only slightly by any of the hydroxamic acid compounds; evidently enzyme-bound manganese (or magnesium) is specific for hydroxamate binding to this aminopeptidase. PMID:6643439

  18. Distribution of perfluorooctane sulfonate isomers and predicted risk of thyroid hormonal perturbation in drinking water.

    PubMed

    Yu, Nanyang; Wang, Xiaoxiang; Zhang, Beibei; Yang, Jingping; Li, Meiying; Li, Jun; Shi, Wei; Wei, Si; Yu, Hongxia

    2015-06-01

    We documented the distribution of seven perfluorooctane sulfonate (PFOS) isomers in drinking water in Jiangsu Province, China. Compared to the 30% proportion of branched PFOS in technical PFOS, the levels of branched PFOS in drinking water increased to 31.8%-44.6% of total PFOS. Because of previous risk assessment without considering the PFOS isomer profile and the toxicity of individual PFOS isomers, here we performed a new health risk assessment of PFOS for thyroid hormonal perturbation in drinking water with the contribution from individual PFOS isomers. The risk quotients (RQs) of individual PFOS isomers indicated that linear PFOS contributed most to the risk among all the target PFOS isomers (83.0%-90.2% of the total PFOS RQ), and that risk from 6m-PFOS (5.2%-11.9% of the total PFOS RQ) was higher than that from other branched PFOS isomers. We found that the risks associated with PFOS in drinking water would be overestimated by 10.0%-91.7% if contributions from individual PFOS isomers were not considered. The results revealed that the PFOS isomer profile and the toxicity of individual PFOS isomers were important factors in health risk assessment of PFOS and should be considered in the future risk assessments. PMID:25813491

  19. Parity nonconservation in the {gamma} decay of polarized 17/2{sup -} isomers in {sup 93}Tc

    SciTech Connect

    Singh, B.S. Nara; Hass, M.; Goldring, G.; Ackermann, D.; Sulignano, B.; Gerl, J.; Hessberger, F.P.; Hofmann, S.; Kojouharov, I.; Kuusiniemi, P.; Schaffner, H.; Brown, B.A.

    2005-08-01

    The determination of the 0 deg. - 180 deg. asymmetry (A{sub {gamma}}), which arises because of the parity nonconserving matrix element, in the 751-keV {gamma} decay of polarized 17/2{sup -} isomers in {sup 93}Tc with respect to the direction of polarization is reported. A combined analysis of the present results together with those from our earlier work yields an effect of two standard deviations.

  20. Experimental study of the excitation of rhodium isomer in a plasma produced by a picosecond laser pulse

    SciTech Connect

    Afonin, V. I.; Kakshin, A. G.; Mazunin, A. V.

    2010-03-15

    Estimates and first experimental results on the excitation of a long-lived isomer state (E{sub m} = 39.756 keV, J{sup p} = 9/2{sup -}, and T{sub 1/2} = 56.114 min) of Rh{sup 103} nuclei under the action of X radiation in a hot solid-state-density rhodium plasma produced by a picosecond laser pulse in the SOKOL-P laser facility are presented.

  1. Determination of benzoic acid, chlorobenzoic acids and chlorendic acid in water

    SciTech Connect

    Dietz, E.A.; Cortellucci, N.J.; Singley, K.F. )

    1993-01-01

    To characterize and conduct treatment studies of a landfill leachate an analysis procedure was required to determine concentrations of benzoic acid, the three isomers of chlorobenzoic acid and chlorendic acid. The title compounds were isolated from acidified (pH 1) water by extraction with methyl t-butyl ether. Analytes were concentrated by back-extracting the ether with 0.1 N sodium hydroxide which was separated and acidified. This solution was analyzed by C[sub 18] reversed-phase HPLC with water/acetonitrile/acetic acid eluent and UV detection at 222 nm. The method has detection limits of 200 [mu]g/L for chlorendic acid and 100 [mu]g/L for benzoic acid and each isomer of chlorobenzoic acid. Validation studies with water which was fortified with the analytes at concentrations ranging from one to ten times detection limits resulted in average recoveries of >95%.

  2. Infrared detection of (H2O)20 isomers of exceptional stability: A drop-like and a face-sharing pentagonal prism cluster

    DOE PAGESBeta

    Pradzynski, Christoph C.; Dierking, Christoph W.; Zurheide, Florian; Forck, Richard M.; Buck, Udo; Zeuch, Thomas; Xantheas, Sotiris S.

    2014-09-01

    Water clusters containing fully coordinated water molecules are model systems that mimic the local environment of the condensed phase. Present knowledge about the water cluster size regime in which the transition from the allsurface to the fully solvated water molecules occurs is mainly based on theoretical predictions in lieu of the absence of precisely size resolved experimental measurements. Here, we report size and isomer selective infrared (IR) spectra of (H2O)20 clusters tagged with a sodium atom by employing IR excitation modulated photoionization spectroscopy. The observed absorption patterns in the OH stretching ”fingerprint” region are consistent with the theoretically predicted spectramore » of two structurally distinct isomers: A drop-like cluster with a fully coordinated (interior) water and an edge-sharing pentagonal prism cluster in which all atoms are on the surface. The observed isomers show exceptional stability and are predicted to be nearly isoenergetic.« less

  3. Performance of some DFT functionals with dispersion on modeling of the translational isomers of a solvent-switchable [2]rotaxane

    NASA Astrophysics Data System (ADS)

    Ivanov, Petko

    2016-03-01

    presented qualitatively correct behavior for the relative stability of the two translational isomers, namely, slight preference of station II for the isolated molecule and higher relative energy of the same isomer with the model solvent DMSO. The electrostatic interactions in 2 have the decisive contribution both when the macroring is positioned at the dipeptide residue for the neutral form, and at the N-benzylalanine fragment after protonation, and the observed behavior of the [2]rotaxane is correctly reproduced by the methods used.

  4. Gastroprotective effect and cytotoxicity of labdeneamides with amino acids.

    PubMed

    Schmeda-Hirschmann, Guillermo; Rodríguez, Jaime A; Theoduloz, Cristina; Valderrama, Jaime A

    2011-03-01

    Semisynthetic aromatic amides from ARAUCARIA ARAUCANA diterpene acids have been shown to display a relevant gastroprotective effect with low cytotoxicity. The aim of this work was to assess the gastroprotective effect of amino acid amides from imbricatolic acid and its 8(9)-en isomer in the ethanol/HCl-induced gastric lesions model in mice as well as to determine the cytotoxicity of the obtained compounds on the following human cell lines: normal lung fibroblasts (MRC-5), gastric adenocarcinoma (AGS), and liver hepatocellular carcinoma (Hep G2). The diterpenes 15-acetoxyimbricatolic acid, its 8(9)-en isomer, 15-hydroxyimbricatolic acid, and the 8(9)-en derivative, bearing a COOH function at C-19, were used as starting compounds. New amides with C-protected amino acids were prepared. The study reports the effect of a single oral administration of either compound 50 min before the induction of gastric lesions by ethanol/HCl. Some 20 amino acid monoamides were obtained. Dose-response experiments on the glycyl derivatives showed that at a single oral dose of 100 mg/kg, the compounds presented an effect comparable to the reference drug lansoprazole at 20 mg/kg and at 50 mg/kg reduced gastric lesions by about 50%. All derivatives obtained in amounts > 30 mg were compared at a single oral dose of 50 mg/kg. The best gastroprotective effect was observed for the exomethylene derivatives bearing a valine residue at C-19 either with an acetoxy or free hydroxy group at C-15. The tryptophanyl derivative from the acetate belonging to the 8,9-en series presented selective cytotoxicity against hepatocytes. The glycyl amide of 15-acetoxyimbricatolic acid was the most cytotoxic and less selective compound with IC₅₀ values between 47 and 103 µM for the studied cell lines. This is the first report on the obtention of semisynthetic amino acid amides from labdane diterpenes. PMID:20862639

  5. Accurate thermochemistry and spectroscopy of the oxygen-protonated sulfur dioxide isomers.

    PubMed

    Puzzarini, Cristina

    2011-12-28

    Despite the promising relevance of protonated sulfur dioxide in astrophysical and atmospheric fields, its thermochemical and spectroscopic characterization is very limited. High-level quantum-chemical calculations have shown that the most stable isomer is the cis oxygen-protonated sulfur dioxide, HOSO(+), while the trans form is about 2 kcal mol(-1) less stable; even less stable (by about 42 kcal mol(-1)) is the S-protonated isomer [V. Lattanzi et al., J. Chem. Phys., 2010, 133, 194305]. The enthalpy of formation for the cis- and trans-HOSO(+) is presented, based on the well tested HEAT protocol [A. Tajti et al., J. Chem. Phys., 2004, 121, 11599]. Systematically extrapolated ab initio energies, accounting for electron correlation through coupled cluster theory, including up to single, double, triple and quadruple excitations, have been corrected for core-electron correlation, anharmonic zero-point vibrational energy, diagonal Born-Oppenheimer and scalar relativistic effects. As a byproduct, proton affinity of sulfur dioxide and atomization energies have also been obtained at the same levels of theory. Vibrational and rotational spectroscopic properties have been investigated by means of composite schemes that allow us to account for truncation of basis set as well as core correlation. Where available, for both thermochemistry and spectroscopy, very good agreement with experimental data has been observed. PMID:22033629

  6. First- and second-electron affinities of C{sub 60} and C{sub 70} isomers

    SciTech Connect

    Zettergren, Henning; Alcami, Manuel; Martin, Fernando

    2007-10-15

    We present density functional theory calculations of C{sub 60}{sup q-} and C{sub 70}{sup q-} (q=0-2) isomers that contain zero to three pairs of adjacent pentagons. The first- and second-electron affinities for the archetype structures of C{sub 60} and C{sub 70} are close to the experimental results, while isomers with pentagon adjacencies have significantly higher values. The results are rationalized in view of the numbers and locations of pentagon adjacencies in the fullerene cages and the spherical aromaticity for the magic number C{sub 70}{sup 2-} with a closed (l=5) electronic shell in the spherical gas model.

  7. In vitro comparison of hepatic metabolism of 9cis-11 trans and 10trans-12cis isomers of CLA in the rat.

    PubMed

    Gruffat, Dominique; De La Torre, Anne; Chardigny, Jean-Michel; Durand, Denys; Loreau, Olivier; Sébédio, Jean-Louis; Bauchart, Dominique

    2003-02-01

    Hepatic metabolism of the two main isomers of CLA (9cis-11trans, 10trans-12cis C18:2) was compared to that of oleic acid (representative of the main plasma FA) in 16 rats by using the in vitro method of incubated liver slices. Liver tissue samples were incubated at 37 degrees C for 17 h under an atmosphere of 95% O2/5% CO2 in a medium supplemented with 0.75 mM of FA mixture (representative of circulating nonesterified FA) and with 55 microM [1-(14)C]9cis-11trans C18:2,11-(14)C]10trans-12cis C18:2, or 11-(14)C]oleate. The uptake of CLA by hepatocytes was similar for both isomers (9%) and was three times higher (P < 0.01) than for oleate (2.6%). The rate of CLA isomer oxidation was two times higher (49 and 40% of incorporated amounts of 9cis-11 trans and 10trans-12cis, respectively) than that of oleate (P < 0.01). Total oxidation of oleate and CLA isomers into [14CO2] was low (2 to 7% of total oxidized FA) compared to the partial oxidation (93 to 98%) leading to the production of [14C] acid-soluble products. CLA isomers escaping from catabolism were both highly desaturated (26.7 and 26.8%) into conjugated 18:3. Oleate and CLA isomers were mainly esterified into neutral lipids (70% of esterifled FA) and, to a lesser extent, into polar lipids (30%). They were slowly secreted as parts of VLDL particles (< 0.4% of FA incorporated into cells), the extent of secretion of oleate and of 10trans-12cis being 2.2-fold higher than that of 9cis-11trans (P < 0.02). In conclusion, this study clearly showed that both CLA isomers were highly catabolized by hepatocytes, reducing their availability for peripheral tissues. Moreover, more than 25% of CLA escaping from catabolism was converted into conjugated 18:3, the biological properties of which remain to be elucidated. PMID:12733748

  8. A strategy for the separation of diterpenoid isomers from the root of Aralia continentalis by countercurrent chromatography: The distribution ratio as a substitute for the partition coefficient and a three-phase solvent system.

    PubMed

    Lee, Kyoung Jin; Song, Kwang Ho; Choi, Wonmin; Kim, Yeong Shik

    2015-08-01

    Aralia continentalis (Araliaceae) is widely used as a medicinal plant in East Asia. Previous studies have indicated that diterpenoid isomers (kaurenoic acid, continentalic acid, and ent-continentalic acid) are the major bioactive compounds of this plant. A new strategy was developed to alleviate difficulties in the separation of these isomers from this plant. A three-phase solvent system was applied to separate the isomers, and furthermore, the distribution ratio (Kc) was introduced as a substitute for the partition coefficient (KD). For compounds exhibiting a single equilibrium, their distributions in two immiscible phases were only affected by the partition coefficient of each solute. However, compounds that have a dissociating functional group (e.g., -COOH) are involved in two types of equilibrium in the two-phase system. In this case, the partitioning behaviors of the solutes are greatly affected by the pH of the solution. A mathematical prediction was applied for adjusting the solutions to the proper pH values. To prevent non-used phase (medium phase) waste, both the stationary phase (upper phase) and mobile phase (lower phase) were prepared on-demand without pre-saturation with the application of (1)H NMR. Each fraction obtained was collected and dried, yielding the following diterpenoid isomers from the 50mg injected sample: kaurenoic acid (19.7mg, yield: 39%) and ent-continentalic acid (21.3mg, yield: 42%). PMID:26138601

  9. Individual CLA Isomers, c9t11 and t10c12, Prevent Excess Liver Glycogen Storage and Inhibit Lipogenic Genes Expression Induced by High-Fructose Diet in Rats

    PubMed Central

    Maslak, Edyta; Buczek, Elzbieta; Szumny, Antoni; Szczepnski, Wojciech; Franczyk-Zarow, Magdalena; Kopec, Aneta; Chlopicki, Stefan; Leszczynska, Teresa; Kostogrys, Renata B.

    2015-01-01

    This study assessed the effects of individual conjugated linoleic acid isomers, c9t11-CLA and t10c12-CLA, on nonalcoholic fatty liver disease (NAFLD) and systemic endothelial dysfunction in rats fed for four weeks with control or high-fructose diet. The high-fructose diet hampered body weight gain (without influencing food intake), increased liver weight and glycogen storage in hepatocytes, upregulated expression of fatty acid synthase (FAS) and stearoyl-CoA desaturase-1 (SCD-1), and increased saturated fatty acid (SFA) content in the liver. Both CLA isomers prevented excessive accumulation of glycogen in the liver. Specifically, t10c12-CLA decreased concentration of serum triacylglycerols and LDL + VLDL cholesterol, increased HDL cholesterol, and affected liver lipid content and fatty acid composition by downregulation of liver SCD-1 and FAS expression. In turn, the c9t11-CLA decreased LDL+VLDL cholesterol in the control group and downregulated liver expression of FAS without significant effects on liver weight, lipid content, and fatty acid composition. In summary, feeding rats with a high-fructose diet resulted in increased liver glycogen storage, indicating the induction of gluconeogenesis despite simultaneous upregulation of genes involved in de novo lipogenesis. Although both CLA isomers (c9t11 and t10c12) display hepatoprotective activity, the hypolipemic action of the t10c12-CLA isomer proved to be more pronounced than that of c9t11-CLA. PMID:26090419

  10. Keto-acids in Carbonaceous Meteorites

    NASA Technical Reports Server (NTRS)

    Cooper, G.; Chang, P. M.; Dugas, A.; Byrd, A.; Chang, P. M.; Washington, N.

    2005-01-01

    The Murchison and Murray meteorites are the best-characterized carbonaceous meteorites with respect to organic chemistry and are generally used as references for organic compounds in extraterrestrial material. Among the classes of organic compounds found in these meteorites are amino acids, carboxylic acids, hydroxy acids, purines, and pyrimidines. Such compounds, important in contemporary biochemistry, are thought to have been delivered to the early Earth in asteroids and comets and may have played a role in early life and/or the origin of life. Absent among (today's) critically important biological compounds reported in carbonaceous meteorites are keto acids, i.e., pyruvic acid, acetoacetic acid, and higher homologs. These compounds are key intermediates in such critical processes as glycolysis and the citric acid cycle. In this study several individual meteoritic keto acids were identified by gas chromatography-mass spectrometry (GC-MS) (see figure below). All compounds were identified as their trimethylsilyl (TMS), isopropyl ester (ISP), and tert-butyldimethylsilyl (tBDMS) derivatives. In general, the compounds follow the abiotic synthesis pattern of other known meteorite classes of organic compounds [1,2]: a general decrease in abundance with increasing carbon number within a class of compounds and many, if not all, possible isomers present at a given carbon number. The majority of the shown compounds was positively identified by comparison of their mass spectra to commercially available standards or synthesized standards.

  11. Sources and Bioactive Properties of Conjugated Dietary Fatty Acids.

    PubMed

    Hennessy, Alan A; Ross, Paul R; Fitzgerald, Gerald F; Stanton, Catherine

    2016-04-01

    The group of conjugated fatty acids known as conjugated linoleic acid (CLA) isomers have been extensively studied with regard to their bioactive potential in treating some of the most prominent human health malignancies. However, CLA isomers are not the only group of potentially bioactive conjugated fatty acids currently undergoing study. In this regard, isomers of conjugated α-linolenic acid, conjugated nonadecadienoic acid and conjugated eicosapentaenoic acid, to name but a few, have undergone experimental assessment. These studies have indicated many of these conjugated fatty acid isomers commonly possess anti-carcinogenic, anti-adipogenic, anti-inflammatory and immune modulating properties, a number of which will be discussed in this review. The mechanisms through which these bioactivities are mediated have not yet been fully elucidated. However, existing evidence indicates that these fatty acids may play a role in modulating the expression of several oncogenes, cell cycle regulators, and genes associated with energy metabolism. Despite such bioactive potential, interest in these conjugated fatty acids has remained low relative to the CLA isomers. This may be partly attributed to the relatively recent emergence of these fatty acids as bioactives, but also due to a lack of awareness regarding sources from which they can be produced. In this review, we will also highlight the common sources of these conjugated fatty acids, including plants, algae, microbes and chemosynthesis. PMID:26968402

  12. Role of Tyrosine Isomers in Acute and Chronic Diseases Leading to Oxidative Stress - A Review.

    PubMed

    Molnár, Gergő A; Kun, Szilárd; Sélley, Eszter; Kertész, Melinda; Szélig, Lívia; Csontos, Csaba; Böddi, Katalin; Bogár, Lajos; Miseta, Attila; Wittmann, István

    2016-01-01

    Oxidative stress plays a major role in the pathogenesis of a variety of acute and chronic diseases. Measurement of the oxidative stress-related end products may be performed, e.g. that of structural isomers of the physiological para-tyrosine, namely meta- and ortho-tyrosine, that are oxidized derivatives of phenylalanine. Recent data suggest that in sepsis, serum level of meta-tyrosine increases, which peaks on the 2(nd) and 3(rd) days (p<0.05 vs. controls), and the kinetics follows the intensity of the systemic inflammation correlating with serum procalcitonin levels. In a similar study subset, urinary meta-tyrosine excretion correlated with both need of daily insulin dose and the insulin-glucose product in non-diabetic septic cases (p<0.01 for both). Using linear regression model, meta-tyrosine excretion, urinary meta-tyrosine/para-tyrosine, urinary ortho-tyrosine/para-tyrosine and urinary (meta- + orthotyrosine)/ para-tyrosine proved to be markers of carbohydrate homeostasis. In a chronic rodent model, we tried to compensate the abnormal tyrosine isomers using para-tyrosine, the physiological amino acid. Rats were fed a standard high cholesterol-diet, and were given para-tyrosine or vehicle orally. High-cholesterol feeding lead to a significant increase in aortic wall meta-tyrosine content and a decreased vasorelaxation of the aorta to insulin and the glucagon-like peptide-1 analogue, liraglutide, that both could be prevented by administration of para-tyrosine. Concluding, these data suggest that meta- and ortho-tyrosine are potential markers of oxidative stress in acute diseases related to oxidative stress, and may also interfere with insulin action in septic humans. Competition of meta- and ortho-tyrosine by supplementation of para-tyrosine may exert a protective role in oxidative stress-related diseases. PMID:26785996

  13. Role of Tyrosine Isomers in Acute and Chronic Diseases Leading to Oxidative Stress - A Review

    PubMed Central

    Molnár, Gergő A.; Kun, Szilárd; Sélley, Eszter; Kertész, Melinda; Szélig, Lívia; Csontos, Csaba; Böddi, Katalin; Bogár, Lajos; Miseta, Attila; Wittmann, István

    2016-01-01

    Oxidative stress plays a major role in the pathogenesis of a variety of acute and chronic diseases. Measurement of the oxidative stress-related end products may be performed, e.g. that of structural isomers of the physiological para-tyrosine, namely meta- and ortho-tyrosine, that are oxidized derivatives of phenylalanine. Recent data suggest that in sepsis, serum level of meta-tyrosine increases, which peaks on the 2nd and 3rd days (p<0.05 vs. controls), and the kinetics follows the intensity of the systemic inflammation correlating with serum procalcitonin levels. In a similar study subset, urinary meta-tyrosine excretion correlated with both need of daily insulin dose and the insulin-glucose product in non-diabetic septic cases (p<0.01 for both). Using linear regression model, meta-tyrosine excretion, urinary meta-tyrosine/para-tyrosine, urinary ortho-tyrosine/para-tyrosine and urinary (meta- + ortho-tyrosine)/para-tyrosine proved to be markers of carbohydrate homeostasis. In a chronic rodent model, we tried to compensate the abnormal tyrosine isomers using para-tyrosine, the physiological amino acid. Rats were fed a standard high cholesterol-diet, and were given para-tyrosine or vehicle orally. High-cholesterol feeding lead to a significant increase in aortic wall meta-tyrosine content and a decreased vasorelaxation of the aorta to insulin and the glucagon-like peptide-1 analogue, liraglutide, that both could be prevented by administration of para-tyrosine. Concluding, these data suggest that meta- and ortho-tyrosine are potential markers of oxidative stress in acute diseases related to oxidative stress, and may also interfere with insulin action in septic humans. Competition of meta- and ortho-tyrosine by supplementation of para-tyrosine may exert a protective role in oxidative stress-related diseases. PMID:26785996

  14. Pentachlorodibenzo-p-dioxin isomer differentiation by capillary gas chromatography Fourier transform infrared spectroscopy

    SciTech Connect

    Grainger, J.; Reddy, V.V.; Patterson D.G. Jr.

    1988-07-01

    Reference infrared vapor-phase spectra of the 14 pentachlorodibenzo-p-dioxin (PnCDD) isomers were recorded at low microgram concentrations. A unique infrared spectrum corresponding to each chromatographically separated or spectrally subtracted mixture component was observed. The structures for individual isomers in each isomer pair were assigned by qualitative valence-bond evaluations and empirically derived quantitative estimations of ether linkage asymmetric stretching frequencies (..nu../sub =/). Correlations between calculated ether linkage (C-O-C) bond angles and ..nu../sub COC(asym)/ indicate the existence of buttressed 1,6 and 1,9 nonbonded interactions not observed in tetrachlorodibenzo-p-dioxin (TCDD) isomers.

  15. The Acetyl Bromide Method Is Faster, Simpler and Presents Best Recovery of Lignin in Different Herbaceous Tissues than Klason and Thioglycolic Acid Methods

    PubMed Central

    Moreira-Vilar, Flavia Carolina; Siqueira-Soares, Rita de Cássia; Finger-Teixeira, Aline; de Oliveira, Dyoni Matias; Ferro, Ana Paula; da Rocha, George Jackson; Ferrarese, Maria de Lourdes L.; dos Santos, Wanderley Dantas; Ferrarese-Filho, Osvaldo

    2014-01-01

    We compared the amount of lignin as determined by the three most traditional methods for lignin measurement in three tissues (sugarcane bagasse, soybean roots and soybean seed coat) contrasting for lignin amount and composition. Although all methods presented high reproducibility, major inconsistencies among them were found. The amount of lignin determined by thioglycolic acid method was severely lower than that provided by the other methods (up to 95%) in all tissues analyzed. Klason method was quite similar to acetyl bromide in tissues containing higher amounts of lignin, but presented lower recovery of lignin in the less lignified tissue. To investigate the causes of the inconsistencies observed, we determined the monomer composition of all plant materials, but found no correlation. We found that the low recovery of lignin presented by the thioglycolic acid method were due losses of lignin in the residues disposed throughout the procedures. The production of furfurals by acetyl bromide method does not explain the differences observed. The acetyl bromide method is the simplest and fastest among the methods evaluated presenting similar or best recovery of lignin in all the tissues assessed. PMID:25330077

  16. Determination of astaxanthin and astaxanthin esters in the microalgae Haematococcus pluvialis by LC-(APCI)MS and characterization of predominant carotenoid isomers by NMR spectroscopy.

    PubMed

    Holtin, Karsten; Kuehnle, Maximilian; Rehbein, Jens; Schuler, Paul; Nicholson, Graeme; Albert, Klaus

    2009-11-01

    The oily product ZANTHIN consists of natural astaxanthin, which is manufactured from the microalgae Haematococcus pluvialis by supercritical CO(2) extraction. An HPLC method was developed to separate all of the components of the complex astaxanthin extract using a C(30) column. The separation resulted in different isomers of astaxanthin accompanied by two other carotenoids. The main component consisted of astaxanthin singly esterified with several different fatty acids. C18:3, C18:2, C18:1 and C16:0 were identified as the most commonly occurring fatty acids. Doubly esterified astaxanthin was also found, although in lower concentrations compared to singly esterified astaxanthin. After performing a detailed fatty acid analysis by GC-MS, the peaks from the extract were assigned via HPLC-MS. A trans to cis transmutation of the all-trans compound was performed by thermal treatment in order to obtain an enrichment of cis isomers as the basis for unambiguous identification via NMR experiments. The all-trans as well as the 9- and 13-cis isomers of astaxanthin were characterized in detail by UV/Vis, (1)H, and (1)H,(1)H COSY NMR spectroscopy. PMID:19466394

  17. The prenucleosome, a stable conformational isomer of the nucleosome

    PubMed Central

    Fei, Jia; Torigoe, Sharon E.; Brown, Christopher R.; Khuong, Mai T.; Kassavetis, George A.; Boeger, Hinrich; Kadonaga, James T.

    2015-01-01

    Chromatin comprises nucleosomes as well as nonnucleosomal histone–DNA particles. Prenucleosomes are rapidly formed histone–DNA particles that can be converted into canonical nucleosomes by a motor protein such as ACF. Here we show that the prenucleosome is a stable conformational isomer of the nucleosome. It consists of a histone octamer associated with ∼80 base pair (bp) of DNA, which is located at a position that corresponds to the central 80 bp of a nucleosome core particle. Monomeric prenucleosomes with free flanking DNA do not spontaneously fold into nucleosomes but can be converted into canonical nucleosomes by an ATP-driven motor protein such as ACF or Chd1. In addition, histone H3K56, which is located at the DNA entry and exit points of a canonical nucleosome, is specifically acetylated by p300 in prenucleosomes relative to nucleosomes. Prenucleosomes assembled in vitro exhibit properties that are strikingly similar to those of nonnucleosomal histone–DNA particles in the upstream region of active promoters in vivo. These findings suggest that the prenucleosome, the only known stable conformational isomer of the nucleosome, is related to nonnucleosomal histone–DNA species in the cell. PMID:26680301

  18. A [10]Annulene isomer may be aromatic, after all

    SciTech Connect

    Sulzbach, H.M.; Schleyer, P.R. von Univ. Erlangen-Nuernberg ); Jiao, H. ); Xie, Y.; Schaefer, H.F. III )

    1995-02-01

    Despite its adherence to Huckel's rule, $LB 10$RB annulene is thought to prefer nonaromatic, nonplanar structures. This seemingly reasonable conclusion is based on experimental studies carried out a quarter century ago, but the detailed nature of the [10]annulene isomers has not been fully elucidated. A new, nearly planar aromatic monotrans [10]annulene configuration has now been characterized at the second-order perturbation (MP2) and density functional (B3LYP) levels of theory. The structure, with a symmetry plane that bisects the molecule, is not a stationary point at uncorrelated levels, but it is the most stable [10]annulene isomer at MP2(fc)/DZd and at higher levels. The inner hydrogen is only bent out of the approximate carbon plane by about 20[degree]. The estimated aromatic stabilization energy (17.7 kcal/mol, after correction for strain), the diamagnetic susceptibility exaltation ([Lambda] = -66.9 ppm cgs, [Lambda][sub Naphtalene] = -28.2), and the upfield NMR chemical shift of the inner hydrogen ([delta] = -6.1 ppm) confirm the aromaticity of this new C[sub s] [10]annulene conformation. 23 refs., 3 figs., 5 tabs.

  19. Observation of new K isomers among neutron-rich rare earth nuclei produced by in-flight fission of 345 MeV/nucleon 238U

    NASA Astrophysics Data System (ADS)

    Kameda, Daisuke; Kubo, Toshiyuki; BigRIPS new isotope Collaboration

    2014-09-01

    We have performed search for new K isomers for a wide range of neutron-rich rare earth nuclei using the BigRIPS separator at RIKEN RIBF. The rare earth nuclei were produced by in-flight fission of a 238U beam at 345 MeV/nucleon, and isomeric gamma rays were detected using four clover-type germanium detectors. As a result, we have observed a total of 25 new microsecond isomers: 158 m , 159 m , 160 mNd, 158 m , 159 m , 161 mPm, 160 m , 161 m , 162 mSm, 163 m , 164 mEu, 162 m , 164 m , 165 m , 166 mGd, 164 m , 165 m , 166 m , 167 m , 168 mTb, 167 m , 168 m , 169 m , 170 mDy, and 171mHo, and obtained a wealth of spectroscopic information on these nuclei. The nuclei in this region are predicted to be well deformed with a prolate shape, and Kisomers are expected to appear due to the K hindrance. In the present measurement, as anticipated, many of the observed new isomers have been interpreted as a K isomer, because we could identify some gamma rays which belong to the grand-state rotational band being fed by isomeric transitions. The systematics of known K isomers, such as those in neighboring higher- Zisotones, also help and support the interpretation of isomerism. Here we will report on the details of the experimental results and discuss the possible configurations of deformed orbits for the observed new K isomers.

  20. Isomer-specific product detection of gas-phase xylyl radical rearrangement and decomposition using VUV synchrotron photoionization.

    PubMed

    Hemberger, Patrick; Trevitt, Adam J; Gerber, Thomas; Ross, Edward; da Silva, Gabriel

    2014-05-22

    Xylyl radicals are intermediates in combustion processes since their parent molecules, xylenes, are present as fuel additives. In this study we report on the photoelectron spectra of the three isomeric xylyl radicals and the subsequent decomposition reactions of the o-xylyl radical, generated in a tubular reactor and probed by mass selected threshold photoelectron spectroscopy and VUV synchrotron radiation. Franck-Condon simulations are applied to augment the assignment of elusive species. Below 1000 K, o-xylyl radicals decompose by hydrogen atom loss to form closed-shell o-xylylene, which equilibrates with benzocyclobutene. At higher temperatures relevant to combustion engines, o-xylylene generates styrene in a multistep rearrangement, whereas the p-xylylene isomer is thermally stable, a key point of difference in the combustion of these two isomeric fuels. Another striking result is that all three xylyl isomers can generate p-xylylene upon decomposition. In addition to C8H8 isomers, phenylacetylene and traces of benzocyclobutadiene are observed and identified as further reaction products of o-xylylene, while there is also some preliminary evidence for benzene and benzyne formation. The experimental results reported here are complemented by a comprehensive theoretical C8H8 potential energy surface, which together with the spectroscopic assignments can explain the complex high-temperature chemistry of o-xylyl radicals. PMID:24679132

  1. Determination of unsaturation grade and trans isomers generated during thermal oxidation of edible oils and fats by FTIR

    NASA Astrophysics Data System (ADS)

    Moya Moreno, M. C. M.; Mendoza Olivares, D.; Amézquita López, F. J.; Gimeno Adelantado, J. V.; Bosch Reig, F.

    1999-05-01

    The oxidative deterioration of culinary oils and fats during episodes of heating associated with normal usage (80°C-300°C, 20-40 min) was monitored by FTIR spectroscopy. The thermal oxidation of polyunsaturated fatty acids during heating was studied by the determination of unsaturation percentage and trans isomers at various temperatures and heating times. Oils frequently used in food frying such as olive oil, sunflower oil, corn oil and seeds oil (sunflower, safflower and canola seed), and lard were studied. The Absorbance Correction Method is proposed to correct the spectral interference and allows the analytic use of signal which would not be initially valid for quantitative analysis. The results show that there is a decrease in unsaturation and an increase in trans isomers starting at 150°C and becomes more pronounced at temperatures around 250°C. This variation in unsaturation grade and conformation provides evidence of the transformation of essential polyunsaturated fatty acids and subsequent decrease in the oils' nutritional value.

  2. Processing Tangerine Tomatoes: Effects on Lycopene-Isomer Concentrations and Profile

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Because lycopene is a powerful biological antioxidant, its delivery to humans is of major concern. Cis-Lycopene isomers are more bioavailable than the all-trans isomer and thus more efficiently absorbed. Tangerine tomatoes, whose lycopene isomeric content is almost all tetra-cis, provide a useful ...

  3. PROCESSING TANGERINE TOMATOES: EFFECTS ON LYCOPENE-ISOMER CONCENTRATION AND PROFILE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Because lycopene is a powerful biological antioxidant, its delivery to humans is of major concern. cis-lycopene isomers are more bioavailable than the all-trans isomers and thus more efficiently absorbed. Tangerine tomatoes, whose lycopene isomeric content is almost all tetra-cis, provide a useful f...

  4. A Highly Sensitive Diketopyrrolopyrrole-Based Ambipolar Transistor for Selective Detection and Discrimination of Xylene Isomers.

    PubMed

    Wang, Bin; Huynh, Tan-Phat; Wu, Weiwei; Hayek, Naseem; Do, Thu Trang; Cancilla, John C; Torrecilla, Jose S; Nahid, Masrur Morshed; Colwell, John M; Gazit, Oz M; Puniredd, Sreenivasa Reddy; McNeill, Christopher R; Sonar, Prashant; Haick, Hossam

    2016-06-01

    An ambipolar poly(diketopyrrolopyrrole-terthiophene)-based field-effect transistor (FET) sensitively detects xylene isomers at low ppm levels with multiple sensing features. Combined with pattern-recognition algorithms, a sole ambipolar FET sensor, rather than arrays of sensors, can discriminate highly similar xylene structural isomers from one another. PMID:26996398

  5. Comparison of some specific polychlorinated biphenyl isomers in human and monkey milk

    SciTech Connect

    Mes, J.; Marchand, L.

    1987-11-01

    The presence and levels of polychlorinated biphenyls (PCBs) in monkey milk have been reported earlier as part of studies which investigated the overall toxicity of PCBs in commercial Aroclors. Some of this information has served as a basis for an estimation of the potential health hazard of PCB contaminated breast milk to human infants. To further support such extrapolation from one primate situation to another, it would be desirable to know not only the levels of PCBs in the milk of these primates, but also the isomeric distribution in order to better evaluate the contribution of each isomer to the overall toxicity. A large concentration in breast milk of an isomer of relatively low toxicity may have the same effect on an infant as a smaller concentration of a highly toxic isomer. This paper compares the relative amounts of 29 selected PCB isomers in human milk and monkey milk samples. The selection of isomers was based on the most prevalent PCB isomers in human milk and represented approximately 80% of all reported isomers. In addition, Aroclor 1254, whose toxicity in monkeys has been investigated recently by several investigators, was analyzed for the same 29 selected PCB isomers.

  6. TETRACHLORODIBENZODIOXIN ISOMER DIFFERENTIATION BY MICRO DIFFUSE REFLECTANCE FOURIER TRANSFORM INFRARED SPECTROMETRY AT THE LOW NANOGRAM LEVEL

    EPA Science Inventory

    Infrared diffuse reflectance spectra were recorded for the 22 tetrachlorodibenzodioxin isomers (TCDDs). By use of micro-DRIFT techniques and signal averaging, identifiable spectra for each of the isomers were achieved at low nanogram levels. Spectral features in the 1200/cm to 16...

  7. 40 CFR 180.436 - Cyfluthrin and the isomer beta-cyfluthrin; tolerances for residues.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... § 180.436, see the List of CFR Sections Affected, which appears in the Finding Aids section of the... 40 Protection of Environment 25 2012-07-01 2012-07-01 false Cyfluthrin and the isomer beta... FOOD Specific Tolerances § 180.436 Cyfluthrin and the isomer beta-cyfluthrin; tolerances for...

  8. 40 CFR 180.418 - Cypermethrin and an isomer zeta-cypermethrin; tolerances for residues.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 25 2013-07-01 2013-07-01 false Cypermethrin and an isomer zeta-cypermethrin; tolerances for residues. 180.418 Section 180.418 Protection of Environment ENVIRONMENTAL... FOOD Specific Tolerances § 180.418 Cypermethrin and an isomer zeta-cypermethrin; tolerances...

  9. 40 CFR 180.436 - Cyfluthrin and the isomer beta-cyfluthrin; tolerances for residues.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... § 180.436, see the List of CFR Sections Affected, which appears in the Finding Aids section of the... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Cyfluthrin and the isomer beta... FOOD Specific Tolerances § 180.436 Cyfluthrin and the isomer beta-cyfluthrin; tolerances for...

  10. 40 CFR 180.418 - Cypermethrin and an isomer zeta-cypermethrin; tolerances for residues.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Cypermethrin and an isomer zeta-cypermethrin; tolerances for residues. 180.418 Section 180.418 Protection of Environment ENVIRONMENTAL... FOOD Specific Tolerances § 180.418 Cypermethrin and an isomer zeta-cypermethrin; tolerances...

  11. 40 CFR 180.436 - Cyfluthrin and the isomer beta-cyfluthrin; tolerances for residues.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... § 180.436, see the List of CFR Sections Affected, which appears in the Finding Aids section of the... 40 Protection of Environment 25 2013-07-01 2013-07-01 false Cyfluthrin and the isomer beta... FOOD Specific Tolerances § 180.436 Cyfluthrin and the isomer beta-cyfluthrin; tolerances for...

  12. 40 CFR 180.436 - Cyfluthrin and the isomer beta-cyfluthrin; tolerances for residues.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... § 180.436, see the List of CFR Sections Affected, which appears in the Finding Aids section of the... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Cyfluthrin and the isomer beta... FOOD Specific Tolerances § 180.436 Cyfluthrin and the isomer beta-cyfluthrin; tolerances for...

  13. 40 CFR 180.436 - Cyfluthrin and the isomer beta-cyfluthrin; tolerances for residues.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... § 180.436, see the List of CFR Sections Affected, which appears in the Finding Aids section of the... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Cyfluthrin and the isomer beta... FOOD Specific Tolerances § 180.436 Cyfluthrin and the isomer beta-cyfluthrin; tolerances for...

  14. Cellular fatty acid composition of cyanobacteria assigned to subsection II, order Pleurocapsales.

    PubMed

    Caudales, R; Wells, J M; Butterfield, J E

    2000-05-01

    The cellular fatty acid composition of five of the six genera of unicellular cyanobacteria in subsection II, Pleurocapsales (Dermocarpa, Xenococcus, Dermocarpella, Myxosarcina and the Pleurocapsa assemblage) contained high proportions of saturated straight-chain fatty acids (26-41% of the total) and unsaturated straight chains (40-67%). Isomers of 16:1 were the main monounsaturated acid component (11-59%). Polyunsaturated acids were present at trace levels (0-1% or less) in Xenococcus and Myxosarcina, at concentrations of less than 7% in Dermocarpa, Dermocarpella, Pleurocapsa and CCMP 1489, and at high concentrations (35% or more) in Chroococcidiopsis. Chroococcidiopsis was also different in terms of the percentage of 16:1 isomers (10-12%) compared to other genera (30-59%), and in terms of total 16-carbon and 18-carbon fatty acids. In general, the composition and heterogeneity of fatty acids in the order Pleurocapsales was similar to that reported for the unicellular cyanobacteria of subsection I, order Chroococcales. PMID:10843042

  15. The Effect of Ursolic Acid on Leishmania (Leishmania) amazonensis Is Related to Programed Cell Death and Presents Therapeutic Potential in Experimental Cutaneous Leishmaniasis

    PubMed Central

    Yamamoto, Eduardo S.; Campos, Bruno L. S.; Jesus, Jéssica A.; Laurenti, Márcia D.; Ribeiro, Susan P.; Kallás, Esper G.; Rafael-Fernandes, Mariana; Santos-Gomes, Gabriela; Silva, Marcelo S.; Sessa, Deborah P.; Lago, João H. G.; Levy, Débora; Passero, Luiz F. D.

    2015-01-01

    Among neglected tropical diseases, leishmaniasis is one of the most important ones, affecting more than 12 million people worldwide. The available treatments are not well tolerated, and present diverse side effects, justifying the search for new therapeutic compounds. In the present study, the activity of ursolic acid (UA) and oleanolic acid (OA) were assayed in experimental cutaneous leishmaniasis (in vitro and in vivo). Promastigote forms of L. amazonensis were incubated with OA and UA for 24h, and effective concentration 50% (EC50) was estimated. Ultraestructural alterations in Leishmania amazonensis promastigotes after UA treatment were evaluated by transmission electron microscopy, and the possible mode of action was assayed through Annexin V and propidium iodide staining, caspase 3/7 activity, DNA fragmentation and transmembrane mitochondrial potential. The UA potential was evaluated in intracellular amastigotes, and its therapeutic potential was evaluated in L. amazonensis infected BALB/c mice. UA eliminated L. amazonensis promastigotes with an EC50 of 6.4 μg/mL, comparable with miltefosine, while OA presented only a marginal effect on promastigote forms at 100 μg/mL. The possible mechanism by which promastigotes were eliminated by UA was programmed cell death, independent of caspase 3/7, but it was highly dependent on mitochondria activity. UA was not toxic for peritoneal macrophages from BALB/c mice, and it was able to eliminate intracellular amastigotes, associated with nitric oxide (NO) production. OA did not eliminate amastigotes nor trigger NO. L. amazonensis infected BALB/c mice submitted to UA treatment presented lesser lesion size and parasitism compared to control. This study showed, for the first time, that UA eliminate promastigote forms through a mechanism associated with programed cell death, and importantly, was effective in vivo. Therefore, UA can be considered an interesting candidate for future tests as a prototype drug for the treatment

  16. Disruption of HLA class II antigen presentation in Burkitt lymphoma: implication of a 47 000 MW acid labile protein in CD4+ T-cell recognition

    PubMed Central

    God, Jason M; Zhao, Dan; Cameron, Christine A; Amria, Shereen; Bethard, Jennifer R; Haque, Azizul

    2014-01-01

    While Burkitt lymphoma (BL) has a well-known defect in HLA class I-mediated antigen presentation, the exact role of BL-associated HLA class II in generating a poor CD4+ T-cell response remains unresolved. Here, we found that BL cells are deficient in their ability to optimally stimulate CD4+ T cells via the HLA class II pathway. This defect in CD4+ T-cell recognition was not associated with low levels of co-stimulatory molecules on BL cells, as addition of external co-stimulation failed to elicit CD4+ T-cell activation by BL. Further, the defect was not caused by faulty antigen/class II interaction, because antigenic peptides bound with measurable affinity to BL-associated class II molecules. Interestingly, functional class II–peptide complexes were formed at acidic pH 5·5, which restored immune recognition. Acidic buffer (pH 5·5) eluate from BL cells contained molecules that impaired class II-mediated antigen presentation and CD4+ T-cell recognition. Biochemical analysis showed that these molecules were greater than 30 000 molecular weight in size, and proteinaceous in nature. In addition, BL was found to have decreased expression of a 47 000 molecular weight enolase-like molecule that enhances class II-mediated antigen presentation in B cells, macrophages and dendritic cells, but not in BL cells. These findings demonstrate that BL likely has multiple defects in HLA class II-mediated antigen presentation and immune recognition, which may be exploited for future immunotherapies. PMID:24628049

  17. Uncovering biologically significant lipid isomers with liquid chromatography, ion mobility spectrometry and mass spectrometry.

    PubMed

    Kyle, Jennifer E; Zhang, Xing; Weitz, Karl K; Monroe, Matthew E; Ibrahim, Yehia M; Moore, Ronald J; Cha, Jeeyeon; Sun, Xiaofei; Lovelace, Erica S; Wagoner, Jessica; Polyak, Stephen J; Metz, Thomas O; Dey, Sudhansu K; Smith, Richard D; Burnum-Johnson, Kristin E; Baker, Erin S

    2016-02-15

    Understanding how biological molecules are generated, metabolized and eliminated in living systems is important for interpreting processes such as immune response and disease pathology. While genomic and proteomic studies have provided vast amounts of information over the last several decades, interest in lipidomics has also grown due to improved analytical technologies revealing altered lipid metabolism in type 2 diabetes, cancer, and lipid storage disease. Mass spectrometry (MS) measurements are currently the dominant approach for characterizing the lipidome by providing detailed information on the spatial and temporal composition of lipids. However, interpreting lipids' biological roles is challenging due to the existence of numerous structural and stereoisomers (i.e. distinct acyl chain and double-bond positions), which are often unresolvable using present approaches. Here we show that combining liquid chromatography (LC) and structurally-based ion mobility spectrometry (IMS) measurement with MS analyses distinguishes lipid isomers and allows insight into biological and disease processes. PMID:26734689

  18. Uncovering biologically significant lipid isomers with liquid chromatography, ion mobility spectrometry and mass spectrometry

    SciTech Connect

    Kyle, Jennifer E.; Zhang, Xing; Weitz, Karl K.; Monroe, Matthew E.; Ibrahim, Yehia M.; Moore, Ronald J.; Cha, Jeeyeon; Sun, Xiaofei; Lovelace, Erica S.; Wagoner, Jessica; Polyak, Stephen J.; Metz, Thomas O.; Dey, Sudhansu K.; Smith, Richard D.; Burnum-Johnson, Kristin E.; Baker, Erin S.

    2016-01-01

    Understanding how biological molecules are generated, metabolized and eliminated in living systems is important for interpreting processes such as immune response and disease pathology. While genomic and proteomic studies have provided vast amounts of information over the last several decades, interest in lipidomics has also grown due to improved analytical technologies revealing altered lipid metabolism in type 2 diabetes, cancer, and lipid storage disease. Liquid chromatography and mass spectrometry (LC-MS) measurements are currently the dominant approach for characterizing the lipidome by providing detailed information on the spatial and temporal composition of lipids. However, interpreting lipids’ biological roles is challenging due to the existence of numerous structural and stereoisomers (i.e. distinct acyl chain and double-bond positions), which are unresolvable using present LC-MS approaches. Here we show that combining structurally-based ion mobility spectrometry (IMS) with LC-MS measurements distinguishes lipid isomers and allows insight into biological and disease processes.

  19. Attractiveness of harlequin bug, Murgantia histrionica, aggregation pheromone: field response to isomers, ratios, and dose.

    PubMed

    Weber, Donald C; Cabrera Walsh, Guillermo; DiMeglio, Anthony S; Athanas, Michael M; Leskey, Tracy C; Khrimian, Ashot

    2014-12-01

    A two-component pheromone, (3S,6S,7R,10S)- and (3S,6S,7R,10R)-10,11-epoxy-1-bisabolen-3-ol (murgantiol), present in emissions from adult male harlequin bugs, Murgantia histrionica, is most attractive in field bioassays to adults and nymphs in the naturally occurring ratio of ca. 1.4:1. Each of the two individual synthetic stereoisomers is highly attractive to male and female adults and nymphs, but is more attractive in combination and when deployed with a harlequin bug host plant. Blends of 8 stereoisomers also are highly attractive, suggesting that isomers not found in the natural pheromone are not repellent. Deployment of an inexpensive non-stereospecific synthetic pheromone holds promise for efficient trapping and/or use in trap-crops for this important pest in North America. PMID:25380993

  20. Manifesting Subtle Differences of Neutral Hydrophilic Guest Isomers in a Molecular Container by Phase Transfer.

    PubMed

    Lee, Hyun Hee L; Lee, Jong Wha; Jang, Yoonjung; Ko, Young Ho; Kim, Kimoon; Kim, Hugh I

    2016-07-11

    Achieving strong host-guest interactions between synthetic hosts and hydrophilic guests in solution is challenging because solvation effects overwhelm other effects. To resolve this issue, we transferred complexes of cucurbit[7]uril (CB[7]) and monosaccharides to the gas phase and report here their intrinsic host-guest chemistry in the absence of solvation effects. It was observed that effective host-guest interactions in the gas phase mediated by ammonium cations allow the differentiation of the monosaccharide isomers in complex with CB[7] upon vibrational excitation. The potential of the unique observation was extended to a quantitative supramolecular analytical method for the monosaccharide guests. The combination of host-guest chemistry and phase transfer presented in this study is an effective approach to overcome current limitations in supramolecular chemistry. PMID:27192972

  1. Chiral separation of deprenyl-N-oxide isomers by capillary electrophoresis using various cyclodextrin derivatives.

    PubMed

    Tábi, Tamás; Halász, Attila Sándor; Pálfi, Melinda; Magyar, Kálmán; Szöko, Eva

    2004-01-01

    Chiral separation of deprenyl-N-oxide isomers is presented using capillary electrophoresis in the presence of various cyclodextrin (CD) derivatives. This recently identified metabolite of R-(-)-deprenyl may possess desirable pharmacological activities. The effect of the cavity size and the substituents of the CD are examined on the enantiomer resolution of the compound having an asymmetric center on a heteroatom. The importance of hydrophilic or hydrogen bonding interaction, as well as the position of the interacting groups is demonstrated. Outstanding selectivity and resolution values are achieved using the chargeable carboxymethyl-beta-CD. 2-Hydroxypropyl-beta-CD is also suitable for the enantiomer separation of the analyte. Native beta-CD and carboxyethyl-beta-CD provide only poor enantioselectivity, whereas heptakis-(2,6-di-O-methyl)-beta-CD is capable of separating only the diastereomers. No chiral resolution can be observed in the presence of gamma-CD. PMID:14965411

  2. Experimental Results from Oak Ridge Isomer Spectrometer and Separator (ORISS)

    NASA Astrophysics Data System (ADS)

    Piechaczek, A.; Batchelder, J. C.; Carter, H. K.; Goans, R. E.; Liu, S.; Shchepunov, V.; Zganjar, E. F.; Unirib Collaboration

    2013-10-01

    ORISS is a linear multi reflection time-of-flight mass analyzer developed by the University Radioactive Ion Beam Consortium. It will be used to separate any isobar and many isomers for decay spectroscopy experiments. The entire system's operation was demonstrated with a less than ideal multi-isotopic ion source and achieved a mass resolving power as high as 430,000. To better characterize the system we have installed a monoisotopic 133Cs ion source. The radiofrequency quadrupole ion cooler and buncher, which serves as the ion injector into ORISS, was tested in stand-alone mode and achieved a longitudinal emittance of 22 π eV × ns and transmission >40%. These very good results confirm our expectation that ORISS can achieve the design goals. Using the improved ion source, we expect, very soon, to demonstrate the complete system's design goals of 400,000 mass resolving power and 50% transmission.

  3. A new NMR approach for the assignment of symmetric isomers.

    PubMed

    Lunazzi, Lodovico; Mazzanti, Andrea

    2004-09-29

    Irradiation of the (13)C satellite (1% natural abundance) of the NMR (1)H signals yields NOE effects on the spatially close hydrogens of the same isotopomer but not on the hydrogens of the 99% isotopomer having only (12)C atoms. In a DPFGSE-NOE sequence, the latter signals are completely canceled, and it is possible, therefore, to detect NOE effects experienced by isochronous lines that would not be otherwise observable. This allows the structural assignments of symmetric isomers to be unambiguously obtained. Examples are reported for the cases of the cis and trans dimethylstilbene, cis and trans stilbeneoxide, 2,5- and 3,4-dimethylthiophene, 1,8- and 1,5-dimethylnaphthalene, syn and anti 1,2-bis(2-methyl-1-naphthyl)benzene, 1,3-cyclooctadiene, and cycloheptatriene. PMID:15382951

  4. Separation and conversion dynamics of nuclear-spin isomers of gaseous methanol

    PubMed Central

    Sun, Zhen-Dong; Ge, Meihua; Zheng, Yujun

    2015-01-01

    All symmetrical molecules with non-zero nuclear spin exist in nature as nuclear-spin isomers (NSIs). However, owing to the lack of experimental information, knowledge is rare about interconversions of NSIs of gaseous molecules with torsional symmetry. Here we report our separation and conversion observations on NSI-torsion-specific transition systems of gaseous methanol from a light-induced drift experiment involving partially spatial separation of the ortho and para isomers. We find that vibrationally excited molecules of the methanol spin isomer have a smaller collision cross-section than their ground-state counterparts. Interconversion of the enriched ortho isomer with the para isomer, which is generally considered improbable, has been quantitatively studied by sensitive detections of the spectral intensities. Rather counterintuitively, this reveals that the interconversion is inhibited with increasing pressure. Our results suggest that the spin conversion mechanism in methanol is via a quantum relaxation process with the quantum Zeno effect induced by molecular collisions. PMID:25880882

  5. Separation and conversion dynamics of nuclear-spin isomers of gaseous methanol

    NASA Astrophysics Data System (ADS)

    Sun, Zhen-Dong; Ge, Meihua; Zheng, Yujun

    2015-04-01

    All symmetrical molecules with non-zero nuclear spin exist in nature as nuclear-spin isomers (NSIs). However, owing to the lack of experimental information, knowledge is rare about interconversions of NSIs of gaseous molecules with torsional symmetry. Here we report our separation and conversion observations on NSI-torsion-specific transition systems of gaseous methanol from a light-induced drift experiment involving partially spatial separation of the ortho and para isomers. We find that vibrationally excited molecules of the methanol spin isomer have a smaller collision cross-section than their ground-state counterparts. Interconversion of the enriched ortho isomer with the para isomer, which is generally considered improbable, has been quantitatively studied by sensitive detections of the spectral intensities. Rather counterintuitively, this reveals that the interconversion is inhibited with increasing pressure. Our results suggest that the spin conversion mechanism in methanol is via a quantum relaxation process with the quantum Zeno effect induced by molecular collisions.

  6. Odd tensor electric transitions in high-spin Sn-isomers and generalized seniority

    NASA Astrophysics Data System (ADS)

    Maheshwari, Bhoomika; Jain, Ashok Kumar

    2016-02-01

    The similar behavior of the B (E 1) values of the recently observed 13- odd tensor E1 isomers and the B (E 2) values of the 10+ and 15- even tensor E2 isomers in the Sn-isotopes has been understood in terms of the generalized seniority for multi-j orbits by using the quasi-spin scheme. This simple approach proves to be quite successful in explaining the measured transition probabilities and the corresponding half-lives in the high-spin isomers of the semi-magic Sn-isotopes. Hence, we show for the first time the occurrence of seniority isomers in the 13- Sn-isomers, which decay by odd-tensor E1 transitions to the same seniority states.

  7. Thermodynamics and kinetics of guest-induced switching between "basket handle" porphyrin isomers.

    PubMed

    Deutman, Alexander B C; Woltinge, Tim; Smits, Jan M M; De Gelder, René; Elemans, Johannes A A W; Nolte, Roeland J M; Rowan, Alan E

    2014-01-01

    The synthesis and switching properties of two "basket handle" porphyrin isomers is described. The cis-oriented meso-phenyl groups of these porphyrins are linked at their ortho-positons via benzocrown-ether-based spacers, which as a result of slow atropisomerization are located either on the same side of the porphyrin plane (cis), or on opposite sides (trans). In solution, the cis-linked isomer slowly isomerizes in the direction of the thermodynamically more stable trans-isomer. In the presence of viologen (N,N'-dialkyl-4,4'-bipyridinium) derivatives, which have different affinities for the two isomers, the isomerization equilibrium could be significantly influenced. In addition, the presence of these guests was found to enhance the rate of the switching process, which was suggested to be caused by favorable interactions between the positively charged guest and the crown ethers of the receptor, stabilizing the transition state energies of the isomerization reaction between the two isomers. PMID:24762966

  8. Attenuated inhibition by levofloxacin, l-isomer of ofloxacin, on GABA response in the dissociated rat hippocampal neurons.

    PubMed

    Imanishi, T; Akahane, K; Akaike, N

    1995-06-30

    The effects of ofloxacin (OFLX) and its isomers, levofloxacin (LVFX) and DR-3354, on the gamma-aminobutyric acid (GABA)-induced Cl- current in acutely dissociated rat hippocampal CA1 neurons were investigated using nystatin perforated patch recording configuration under voltage-clamp conditions. At 10(-5) M these 3 compounds themselves did not affect the GABA response. Biphenylacetic acid (BPA) at 10(-5) M also had no effect on the GABA response, but BPA greatly suppressed the GABA response in combination with these 3 compounds without affecting the reversal potential of GABA response. The inhibitory effects of OFLX and DR-3354 on the GABA response were stronger than that of LVFX. LVFX inhibited the response in a competitive and voltage-independent manner. The results suggest that LVFX has lower CNS adverse effects, such as convulsions, compared to OFLX. PMID:7478164

  9. Table of superdeformed nuclear bands and fission isomers

    SciTech Connect

    Firestone, R.B.; Singh, B.

    1994-06-01

    A minimum in the second potential well of deformed nuclei was predicted and the associated shell gaps are illustrated in the harmonic oscillator potential shell energy surface calculations shown in this report. A strong superdeformed minimum in {sup 152}Dy was predicted for {beta}{sub 2}-0.65. Subsequently, a discrete set of {gamma}-ray transitions in {sup 152}DY was observed and, assigned to the predicted superdeformed band. Extensive research at several laboratories has since focused on searching for other mass regions of large deformation. A new generation of {gamma}-ray detector arrays is already producing a wealth of information about the mechanisms for feeding and deexciting superdeformed bands. These bands have been found in three distinct regions near A=l30, 150, and 190. This research extends upon previous work in the actinide region near A=240 where fission isomers were identified and also associated with the second potential well. Quadrupole moment measurements for selected cases in each mass region are consistent with assigning the bands to excitations in the second local minimum. As part of our committment to maintain nuclear structure data as current as possible in the Evaluated Nuclear Structure Reference File (ENSDF) and the Table of Isotopes, we have updated the information on superdeformed nuclear bands. As of April 1994, we have complied data from 86 superdeformed bands and 46 fission isomers identified in 73 nuclides for this report. For each nuclide there is a complete level table listing both normal and superdeformed band assignments; level energy, spin, parity, half-life, magneto moments, decay branchings; and the energies, final levels, relative intensities, multipolarities, and mixing ratios for transitions deexciting each level. Mass excess, decay energies, and proton and neutron separation energies are also provided from the evaluation of Audi and Wapstra.

  10. Structures, bonding and energies of N 6 isomers

    NASA Astrophysics Data System (ADS)

    Glukhovtsev, Mikhail N.; von Ragué Schleyer, Paul

    1992-10-01

    The most stable N 6 isomer, a twisted open-chain C 2 structure, is 188.3 kcal/mol (MP4SDTQ/6-31G(d)//MP2(full)/6-31 G(d) + ZPE(MP2/6-31 G(d))) higher in energy than three N 2 molecules. In contrast to benzene, hexazine, N 6, prefers a non-planar twist-boat D 2 structure, but this is 26.0 kcal/mol less stable than the C 2 form. The D 6h altenative is a second-order saddle point at MP2 (full)/6-31G(d) 2.1 kcal/mol higher in energy at MP4SDTQ/6-311 (+s)G(d)//MP2(full)/6-311 (+s)G(2d) + ZPE (MP2/6-31G(d)). The homodesmotic and hyperhomodesmotic reaction energies indicate that the D 6h structure is destabilized (-17.6 and -10.4 kcal/mol, respectively), in contrast to the stabilization of benzene (23.9 and 20.3 kcal/mol, respectively, MP4SDTQ/6-31 G(d, p)//MP2(full)/6-31 G(d, p)). NBO analysis shows that none of the N atoms in the N 6 open-chain structures forms more than four covalent bonds. The other N 6 valence isomers, hexaaza-Dewar-benzene, hexaazabicyclopropenyl, and hexaazaprismane are higher in energy than hexazine (33.9, 29.6 and 115.8 kcal/mol, respectively) at MP4SDTQ(fc)/6-31 G(d)/MP2(full)/6-31 G(d) + ZPE(HF/6-31 G(d)).

  11. Tetrachlorodibenzo-p-dioxin isomer differentiation by capillary gas chromatography fourier transform-infrared spectroscopy

    SciTech Connect

    Grainger, J.; Gelbaum, L.T.

    1987-07-01

    Reference infrared vapor-phase spectra of the 22 tetrachlorodibenzodioxin (TCDD) isomers were recorded at low microgram concentrations. These reference spectra of synthetic mixture components separated chromatographically or by spectra subtraction exhibit distinct infrared spectra for each isomer. The infrared frequencies are delineated in correlation tables and are interpreted in terms of substitution patterns which determine the strength of the ether linkage. Absorbance values in the 1330-1280 cm (C-O-C asymmetric stretch) region correlate with specific substitution patterns and molecular geometry. Relative electron-with-drawing capacities for chlorinated aromatic rings in TCDD isomers were estimated on the basis of relative capacities determined for model compounds. Qualitative correlations were established between electron-with-drawing capacities and the effects of resonance and field interactions on the ether linkage absorption frequencies of individual TCDD isomers. Gas chromatography Fourier transform infrared (GC/FT-IR) isomer assignments are generally consistent with those obtained by proton Fourier transform nuclear magnetic resonance ( H FT/NMR) and flame ionization gas chromatography (GC/FID). A chromatographically independent method of assigning TCDD isomer structures on the basis of ether linkage asymmetric stretching frequencies was established by utilization of valence-bond approximations. GC/FT-IR assignments for several TCDD isomers differ from isomer assignments in previously publised results. A user-generated, vapor-phase reference library, containing individual TCDD spectra and spectra of isomer pairs that are incompletely resolved on chromatographic columns, correctly identified each isomer in variety of mixtures by means of a software algorithm.

  12. The Development of a Specific and Sensitive LC-MS-Based Method for the Detection and Quantification of Hydroperoxy- and Hydroxydocosahexaenoic Acids as a Tool for Lipidomic Analysis

    PubMed Central

    Derogis, Priscilla B. M. C.; Freitas, Florêncio P.; Marques, Anna S. F.; Cunha, Daniela; Appolinário, Patricia P.; de Paula, Fernando; Lourenço, Tiago C.; Murgu, Michael; Di Mascio, Paolo; Medeiros, Marisa H. G.; Miyamoto, Sayuri

    2013-01-01

    Docosahexaenoic acid (DHA) is an n-3 polyunsaturated fatty acid that is highly enriched in the brain, and the oxidation products of DHA are present or increased during neurodegenerative disease progression. The characterization of the oxidation products of DHA is critical to understanding the roles that these products play in the development of such diseases. In this study, we developed a sensitive and specific analytical tool for the detection and quantification of twelve major DHA hydroperoxide (HpDoHE) and hydroxide (HDoHE) isomers (isomers at positions 4, 5, 7, 8, 10, 11, 13, 14, 16, 17, 19 and 20) in biological systems. In this study, HpDoHE were synthesized by photooxidation, and the corresponding hydroxides were obtained by reduction with NaBH4. The isolated isomers were characterized by LC-MS/MS, and unique and specific fragment ions were chosen to construct a selected reaction monitoring (SRM) method for the targeted quantitative analysis of each HpDoHE and HDoHE isomer. The detection limits for the LC-MS/MS-SRM assay were 1−670 pg for HpDoHE and 0.5−8.5 pg for HDoHE injected onto a column. Using this method, it was possible to detect the basal levels of HDoHE isomers in both rat plasma and brain samples. Therefore, the developed LC-MS/MS-SRM can be used as an important tool to identify and quantify the hydro(pero)xy derivatives of DHA in biological system and may be helpful for the oxidative lipidomic studies. PMID:24204871

  13. Antisickling properties of divanilloylquinic acids isolated from Fagara zanthoxyloides Lam. (Rutaceae).

    PubMed

    Ouattara, B; Jansen, O; Angenot, L; Guissou, I P; Frédérich, M; Fondu, P; Tits, M

    2009-03-01

    Fagara zanthoxyloides Lam. (syn. Zanthoxylum zanthoxyloides) (Rutaceae) is the most cited Fagara species for the treatment and the prevention of sickle cell disease crisis. Sickle cell anemia (SCA) is a public health problem in many countries particularly in Africa. The present study was designed to evaluate the antisickling properties of three isomeric divanilloylquinic acids (3,4-O-divanilloylquinic acid or burkinabin A; 3,5-O-divanilloylquinic acid or burkinabin B and 4,5-O-divanilloylquinic acid or burkinabin C) identified previously by LC/MS/NMR analysis in the root bark of F. zanthoxyloides [Ouattara et al., 2004. LC/MS/NMR analysis of isomeric divanilloylquinic acids from the root bark of Fagara zanthoxyloides Lam. Phytochemistry 65, 1145-1151]. The three isomers showed interesting antisickling properties which increased from burkinabins A to C. PMID:19110407

  14. β-N-methylamino-l-alanine (BMAA) and isomers: Distribution in different food web compartments of Thau lagoon, French Mediterranean Sea.

    PubMed

    Réveillon, Damien; Abadie, Eric; Séchet, Véronique; Masseret, Estelle; Hess, Philipp; Amzil, Zouher

    2015-09-01

    The neurotoxin BMAA (β-N-methylamino-l-alanine) and its isomer DAB (2,4-diaminobutyric acid) have been detected in seafood worldwide, including in Thau lagoon (French Mediterranean Sea). A cluster of amyotrophic lateral sclerosis (ALS), a neurodegenerative disease associated with BMAA, has also been observed in this region. Mussels, periphyton (i.e. biofilms attached to mussels) and plankton were sampled between July 2013 and October 2014, and analyzed using HILIC-MS/MS. BMAA, DAB and AEG (N-(2-aminoethyl)glycine) were found in almost all the samples of the lagoon. BMAA and DAB were present at 0.58 and 0.83, 2.6 and 3.3, 4.0 and 7.2 μg g(-1) dry weight in plankton collected with nets, periphyton and mussels, respectively. Synechococcus sp., Ostreococcus tauri, Alexandrium catenella and eight species of diatoms were cultured and screened for BMAA and analogs. While Synechococcus sp., O. tauri and A. catenella did not produce BMAA under our culture conditions, four diatoms species contained both BMAA and DAB. Hence, diatoms may be a source of BMAA for mussels. Unlike other toxins produced by microalgae, BMAA and DAB were detected in significant amounts in tissues other than digestive glands in mussels. PMID:26254582

  15. Lipids in the diet and the fatty acid profile in beef: a review and recent patents on the topic.

    PubMed

    Ladeira, Marcio M; Machado Neto, Otavio R; Chizzotti, Mario L; Oliveira, Dalton M; Chalfun Junior, Antonio

    2012-08-01

    The objective of this review is to report how the use of lipid sources in diets for ruminants can affect the fatty acid profile of beef. In addition, recent patents that can be utilized to alter the fatty acid profile in the meat, or which concern the synthesis of conjugated fatty acids will be reviewed. The industrial production of conjugated linoleic acid (CLA) has already started and the commercial products present isomers cis-9, trans-11; trans-9, cis-11; and trans-10, cis-12. Patents on the biological synthesis of isomer C18:2 cis-9, trans-11 from the linoleic acid have also been published. However, the economic production of CLA in industrial scale is a difficult process. Most of the patents published for CLA production utilize bacteria of the genera Bifidobacterium sp. and Propionibacterium sp. Lipid supplementation, with the objective to improve the fatty acid profile of beef, can be done through the use of patented products, such as genetically modified oilseeds and calcium soaps of fatty acids. PMID:22702746

  16. Graphene-ZIF8 composite material as stationary phase for high-resolution gas chromatographic separations of aliphatic and aromatic isomers.

    PubMed

    Yang, Xiaohong; Li, Changxia; Qi, Meiling; Qu, Liangti

    2016-08-19

    This work presents the separation performance of graphene-ZIF8 (G-Z) composite material as stationary phase for capillary gas chromatography (GC). The G-Z stationary phase achieved high column efficiency of 5000 plates/m determined by n-dodecane (k=1.22) at 120°C and showed weakly polar nature. Importantly, it exhibited high selectivity and resolving capability for branched alkane isomers and aromatic positional isomers, showing clear advantages over the reported neat graphene and ZIF8. In addition, it attained high resolution for geometric cis-/trans-isomers. The G-Z column exhibited good column thermal stability up to 300°C and column repeatability with RSD values of retention times in the range of 0.01-0.19% for intra-day, 0.05-0.88% for inter-day and 0.66-5.6% for between-column, respectively, Moreover, the G-Z column was employed for the determination of minor impurity isomers in real reagent samples, which demonstrates its promising potential in GC applications. PMID:27423773

  17. The use of fatty acid methyl ester analysis (FAME) for the identification of heterotrophic bacteria present on three mural paintings showing severe damage by microorganisms.

    PubMed

    Heyrman, J; Mergaert, J; Denys, R; Swings, J

    1999-12-01

    Mural paintings in Carmona (Spain), Herberstein (Austria) and Greene (Germany), showing visible deterioration by microorganisms, were sampled to investigate the biodiversity of the heterotrophic bacteria present. Four hundred twenty-eight bacterial strains were isolated from which 385 were characterized by fatty acid methyl ester analysis (FAME). The isolates were grouped into 41 clusters on the basis of their FAME profiles, 20 isolates remained ungrouped. The majority (94%) of the isolates comprised the gram-positive bacteria and the main clusters were identified as Bacillus sp., Paenibacillus sp., Micrococcus sp., Arthrobacter sp. and Staphylococcus sp. Other clusters contain nocardioform actinomycetes and gram-negative bacteria, respectively. A cluster of the latter contained extreme halotolerant bacteria isolated in Herberstein. The FAME profiles of this cluster showed a high similarity with Halomonas. PMID:10564789

  18. Rare Form of Erdheim-Chester Disease Presenting with Isolated Central Skeletal Lesions Treated with a Combination of Alfa-Interferon and Zoledronic Acid

    PubMed Central

    Bulycheva, E. N.; Baykov, V. V.; Zaraĭskiĭ, M. I.; Salogub, G. N.

    2015-01-01

    Erdheim-Chester disease (ECD) represents a clonal non-Langerhans histiocytosis, which manifests under an extensive variety of clinical symptoms. This creates a challenge for the physician, who is required to recognize and diagnose the disease in the early stages. Despite this considerable challenge, in the last decade there has been a dramatic increase in ECD diagnoses, in most part due to an increasing awareness of this rare disorder. Involvement of the axial skeleton is exclusively uncommon with no official recommendations for the treatment of the bone lesions. Here, we present a case report of a young male patient with isolated lesions of the spine, ribs, and pelvis, who was successfully treated with a combination therapy of alfa-interferon and zoledronic acid. PMID:25949835

  19. 40 CFR 180.438 - Lambda-cyhalothrin and an isomer gamma-cyhalothrin; tolerances for residues.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Lambda-cyhalothrin and an isomer gamma... FOOD Specific Tolerances § 180.438 Lambda-cyhalothrin and an isomer gamma-cyhalothrin; tolerances for... established for the combined residues of the pyrethroid [gamma-cyhalothrin (the isolated active isomer...

  20. 40 CFR 180.438 - Lambda-cyhalothrin and an isomer gamma-cyhalothrin; tolerances for residues.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Lambda-cyhalothrin and an isomer gamma... FOOD Specific Tolerances § 180.438 Lambda-cyhalothrin and an isomer gamma-cyhalothrin; tolerances for... established for the combined residues of the pyrethroid [gamma-cyhalothrin (the isolated active isomer...

  1. 40 CFR 180.438 - Lambda-cyhalothrin and an isomer gamma-cyhalothrin; tolerances for residues.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 25 2013-07-01 2013-07-01 false Lambda-cyhalothrin and an isomer gamma... FOOD Specific Tolerances § 180.438 Lambda-cyhalothrin and an isomer gamma-cyhalothrin; tolerances for... established for the combined residues of the pyrethroid [gamma-cyhalothrin (the isolated active isomer...

  2. 40 CFR 180.157 - Methyl 3-[(dimethoxyphos-phinyl) oxy]butenoate, alpha and beta isomers; tolerances for residues.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... isomers; tolerances for residues. 180.157 Section 180.157 Protection of Environment ENVIRONMENTAL... FOOD Specific Tolerances § 180.157 Methyl 3- butenoate, alpha and beta isomers; tolerances for residues... and beta isomers, in or on the following raw agricultural commodities: Commodity Parts per...

  3. 40 CFR 180.157 - Methyl 3-[(dimethoxyphos-phinyl) oxy]butenoate, alpha and beta isomers; tolerances for residues.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... isomers; tolerances for residues. 180.157 Section 180.157 Protection of Environment ENVIRONMENTAL... FOOD Specific Tolerances § 180.157 Methyl 3- butenoate, alpha and beta isomers; tolerances for residues... and beta isomers, in or on the following raw agricultural commodities: Commodity Parts per...

  4. 40 CFR 180.438 - Lambda-cyhalothrin and an isomer gamma-cyhalothrin; tolerances for residues.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Lambda-cyhalothrin and an isomer gamma... FOOD Specific Tolerances § 180.438 Lambda-cyhalothrin and an isomer gamma-cyhalothrin; tolerances for... established for the combined residues of the pyrethroid [gamma-cyhalothrin (the isolated active isomer...

  5. 40 CFR 180.438 - Lambda-cyhalothrin and an isomer gamma-cyhalothrin; tolerances for residues.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 25 2012-07-01 2012-07-01 false Lambda-cyhalothrin and an isomer gamma... FOOD Specific Tolerances § 180.438 Lambda-cyhalothrin and an isomer gamma-cyhalothrin; tolerances for... established for the combined residues of the pyrethroid [gamma-cyhalothrin (the isolated active isomer...

  6. Collision-Induced Dissociation of Fatty Acid [M - 2H + Na]- Ions: Charge-Directed Fragmentation and Assignment of Double Bond Position

    NASA Astrophysics Data System (ADS)

    Thomas, Michael C.; Altvater, Jens; Gallagher, Thomas J.; Nette, Geoffrey W.

    2014-08-01

    The collision-induced dissociation (CID) of cationic fatty acid-metal ion complexes has been extensively studied and, in general, provides rich structural information. In particular, charge-remote fragmentation processes are commonly observed allowing the assignment of double bond position. In a previous manuscript, we presented two methods to doubly deprotonate polyunsaturated fatty acids to form anionic fatty acid-sodium ion complexes, referred to as [M - 2H + Na] - ions. In the current manuscript, the CID behavior of these [M - 2H + Na] - ions is investigated for the first time. Significantly, we also present a deuterium-labeling experiment, which excludes the possibility that deprotonation occurs predominately at the α-carbon in the formation of fatty acid [M - H + NaF]- ions. This supports our original proposal where deprotonation occurs at the bis-allylic positions of polyunsaturated fatty acids. CID spectra of polyunsaturated fatty acid [M - 2H + Na]- ions display abundant product ions arising from acyl chain cleavages. Through the examination of fatty acid isomers, it is demonstrated that double bond position may be unequivocally determined for methylene-interrupted polyunsaturated fatty acids with three or more carbon-carbon double bonds. In addition, CID of [M - 2H + Na]- ions was applied to 18:3 isomers of Nannochloropsis oculata and three isomers were tentatively identified: ∆9,12,1518:3, ∆6,9,1218:3, and ∆5,8,1118:3. We propose that structurally-informative product ions are formed via charge-driven fragmentation processes at the site of the resonance-stabilized carbanion as opposed to charge-remote fragmentation processes, which could be inferred if deprotonation occurred predominately at the α-carbon.

  7. Decay and Fission Hindrance of Two- and Four-Quasiparticle K Isomers in 254Rf

    NASA Astrophysics Data System (ADS)

    David, H. M.; Chen, J.; Seweryniak, D.; Kondev, F. G.; Gates, J. M.; Gregorich, K. E.; Ahmad, I.; Albers, M.; Alcorta, M.; Back, B. B.; Baartman, B.; Bertone, P. F.; Bernstein, L. A.; Campbell, C. M.; Carpenter, M. P.; Chiara, C. J.; Clark, R. M.; Cromaz, M.; Doherty, D. T.; Dracoulis, G. D.; Esker, N. E.; Fallon, P.; Gothe, O. R.; Greene, J. P.; Greenlees, P. T.; Hartley, D. J.; Hauschild, K.; Hoffman, C. R.; Hota, S. S.; Janssens, R. V. F.; Khoo, T. L.; Konki, J.; Kwarsick, J. T.; Lauritsen, T.; Macchiavelli, A. O.; Mudder, P. R.; Nair, C.; Qiu, Y.; Rissanen, J.; Rogers, A. M.; Ruotsalainen, P.; Savard, G.; Stolze, S.; Wiens, A.; Zhu, S.

    2015-09-01

    Two isomers decaying by electromagnetic transitions with half-lives of 4.7(1.1) and 247 (73 ) μ s have been discovered in the heavy 254Rf nucleus. The observation of the shorter-lived isomer was made possible by a novel application of a digital data acquisition system. The isomers were interpreted as the Kπ=8- , ν2(7 /2+[624 ],9 /2-[734 ]) two-quasineutron and the Kπ=1 6+, 8-ν2(7 /2+[624 ],9 /2-[734 ])⊗8-π2(7 /2-[514 ],9 /2+[624 ]) four-quasiparticle configurations, respectively. Surprisingly, the lifetime of the two-quasiparticle isomer is more than 4 orders of magnitude shorter than what has been observed for analogous isomers in the lighter N =150 isotones. The four-quasiparticle isomer is longer lived than the 254Rf ground state that decays exclusively by spontaneous fission with a half-life of 23.2 (1.1 ) μ s . The absence of sizable fission branches from either of the isomers implies unprecedented fission hindrance relative to the ground state.

  8. Structural-based differences in ecotoxicity of benzoquinoline isomers to the zebra mussel (Dreissena polymorpha)

    SciTech Connect

    Kraak, M.H.S.; Wijnands, P.; Govers, H.A.J.; Admiraal, W.; Voogt, P. de

    1997-10-01

    Effects of four benzoquinoline isomers on the filtration rate of the zebra mussel (Dreissena polymorpha) were analyzed, to study the effect of minor differences in chemical structure on adverse biological effects. Filtration rates were measured after 48 h of exposure to different concentrations of acridine, phenanthridine, benzo[f]quinoline, and benzo[h]quinoline in the water. The 50% effective concentration (EC50) values for filtration rate of the four isomers differed significantly. Effects increased in the order benzo[f], -[h], -[b], and -[c]quinoline, and the difference between the most toxic isomer and the least toxic isomer amounted to a factor of 30. Attempts were made to relate these differences in toxicity to the structure of the isomers. Size- or topology-related molecular descriptors provided insufficient resolution to distinguish between the benzoquinoline isomers, and none of the electronic descriptors separately provided a significant correlation with the observed effects. In an alternative approach, molecular shape, accessibility, and minimum agent-macromolecule distance were used to represent repulsive and attractive forces between the benzoquinoline isomers and biological membranes. This approach could tentatively explain the observed effects and is supported by a high correlation between the EC50 data and the reversed-phase C18-HPLC behavior of the benzoquinolines (k{sub 0}), which is likely to be governed by similar processes.

  9. Gas-phase Ion Isomer Analysis Reveals the Mechanism of Peptide Sequence Scrambling

    PubMed Central

    Jia, Chenxi; Wu, Zhe; Lietz, Christopher B.; Liang, Zhidan; Cui, Qiang; Li, Lingjun

    2014-01-01

    Peptide sequence scrambling during mass spectrometry-based gas-phase fragmentation analysis causes misidentification of peptides and proteins. Thus, there is a need to develop an efficient approach to probing the gas-phase fragment ion isomers related to sequence scrambling and the underlying fragmentation mechanism, which will facilitate the development of bioinformatics algorithm for proteomics research. Herein, we report on the first use of electron transfer dissociation (ETD)-produced diagnostic fragment ions to probe the components of gas-phase peptide fragment ion isomers. In combination with ion mobility spectrometry (IMS) and formaldehyde labeling, this novel strategy enables qualitative and quantitative analysis of b-type fragment ion isomers. ETD fragmentation produced diagnostic fragment ions indicative of the precursor ion isomer components, and subsequent IMS analysis of b ion isomers provided their quantitative and structural information. The isomer components of three representative b ions (b9, b10, and b33 from three different peptides) were accurately profiled by this method. IMS analysis of the b9 ion isomers exhibited dynamic conversion among these structures. Furthermore, molecular dynamics simulation predicted theoretical drift time values which were in good agreement with experimentally measured values. Our results strongly support the mechanism of peptide sequence scrambling via b ion cyclization, and provide the first experimental evidence to support that the conversion from molecular precursor ion to cyclic b ion (M→cb) pathway is less energetically (or kinetically) favored. PMID:24313304

  10. Search for a 2-quasiparticle high-K isomer in {sup 256}Rf

    SciTech Connect

    Robinson, A. P.; Jenkins, D. G.; Marley, P.; Khoo, T. L.; Seweryniak, D.; Ahmad, I.; Back, B. B.; Carpenter, M. P.; Davids, C. N.; Greene, J.; Janssens, R. V. F.; Kondev, F. G.; Lauritsen, T.; Lister, C. J.; McCutchan, E.; Peterson, D.; Stefanescu, I.; Zhu, S.; Asai, M.; Chowdhury, P.

    2011-06-15

    The energies of 2-quasiparticle (2-qp) states in heavy shell-stabilized nuclei provide information on the single-particle states that are responsible for the stability of superheavy nuclei. We have calculated the energies of 2-qp states in {sup 256}Rf, which suggest that a long-lived, low-energy 8{sup -} isomer should exist. A search was conducted for this isomer through a calorimetric conversion electron signal, sandwiched in time between implantation of a {sup 256}Rf nucleus and its fission decay, all within the same pixel of a double-sided Si strip detector. A 17(5)-{mu}s isomer was identified. However, its low population, {approx}5(2)% that of the ground state instead of the expected {approx}30%, suggests that it is more likely a 4-qp isomer. Possible reasons for the absence of an electromagnetic signature of a 2-qp isomer decay are discussed. These include the favored possibility that the isomer decays by fission, with a half-life indistinguishably close to that of the ground state. Another possibility, that there is no 2-qp isomer at all, would imply an abrupt termination of axially symmetric deformed shapes at Z=104, which describes nuclei with Z=92-103 very well.

  11. Search for a 2-quasiparticle high-K isomer in {sup 256}Rf.

    SciTech Connect

    Robinson, A. P.; Khoo, T. L.; Seweryniak, D.; Ahmad, I.; Asai, M.; Back, B. B.; Carpenter, M. P.; Davids, C. N.; Greene, J.; Janssens, R. V. F.; Kondev, F. G.; Lauritsen, T.; Lister, C. J.; McCutchan, E.; Peterson, D.; Zhu, S.

    2011-06-13

    The energies of 2-quasiparticle (2-qp) states in heavy shell-stabilized nuclei provide information on the single-particle states that are responsible for the stability of superheavy nuclei. We have calculated the energies of 2-qp states in {sup 256}Rf, which suggest that a long-lived, low-energy 8{sup -} isomer should exist. A search was conducted for this isomer through a calorimetric conversion electron signal, sandwiched in time between implantation of a {sup 256}Rf nucleus and its fission decay, all within the same pixel of a double-sided Si strip detector. A 17(5)-{micro}s isomer was identified. However, its low population, {approx}5(2)% that of the ground state instead of the expected {approx}30%, suggests that it is more likely a 4-qp isomer. Possible reasons for the absence of an electromagnetic signature of a 2-qp isomer decay are discussed. These include the favored possibility that the isomer decays by fission, with a half-life indistinguishably close to that of the ground state. Another possibility, that there is no 2-qp isomer at all, would imply an abrupt termination of axially symmetric deformed shapes at Z = 104, which describes nuclei with Z = 92-103 very well.

  12. Isomer-specific investigation of PCDD/F mobility and other fate processes in deep soil cores.

    PubMed

    Grant, Sharon; Stevenson, Gavin; Malcolm, Don; Zennegg, Markus; Gaus, Caroline

    2015-10-01

    Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) are highly hydrophobic compounds with low migration potential in soil-water. Nevertheless, they have been occasionally reported in subsurface soils hypothesised as the result of facilitated transport processes with colloids or surfactants, or yet unidentified in-situ formation processes. To date, however, the prevalence of deep soil contamination, involved processes and their kinetics remain poorly understood. This study investigated PCDD/F concentrations and isomer profiles through deep soil cores (to 20 m) from agricultural, industrial and urban sites in Queensland, Australia. Based on isomer profiles, a unique source common to all core soils (regardless of depth) was identified, dominated by octachlorodibenzo-p-dioxin (OCDD). The source was consistent with contamination resulting from pesticide impurities. Elevated PCDD concentrations (μg/kg range) to depths up to ∼4-17 m and a continuous increase of peri-chlorinated (1,4,6,9-substituted) isomers through the cores suggested that vertical transport and lateral dechlorination were key post-depositional processes at these sites. The mobility of PCDDs in the present study is far greater than previously reported in soils in general. High estimated mass transport rates for OCDD in four agricultural cores (3.0-6.2% year(-1)) likely reflect significant levels of facilitating species, including surfactants, and intensive rainfall at these sites. The implications of such extensive subsurface transport of PCDD/Fs for groundwater contamination and load estimates may be significant. If the cores of the present study are assumed representative of the region, a total PCDD/F load in the order of 800 tonnes (1.6 tonnes TEQ) could be present in subsurface Queensland coastal soils. PMID:26025295

  13. Detailed Chemical Kinetic Reaction Mechanisms for Autoignition of Isomers of Heptane Under Rapid Compression

    SciTech Connect

    Westbrook, C K; Pitz, W J; Boercker, J E; Curran, H J; Griffiths, J F; Mohamed, C; Ribaucour, M

    2001-12-17

    Detailed chemical kinetic reaction mechanisms are developed for combustion of all nine isomers of heptane (C{sub 7}H{sub 16}), and these mechanisms are tested by simulating autoignition of each isomer under rapid compression machine conditions. The reaction mechanisms focus on the manner in which the molecular structure of each isomer determines the rates and product distributions of possible classes of reactions. The reaction pathways emphasize the importance of alkylperoxy radical isomerizations and addition reactions of molecular oxygen to alkyl and hydroperoxyalkyl radicals. A new reaction group has been added to past models, in which hydroperoxyalkyl radicals that originated with abstraction of an H atom from a tertiary site in the parent heptane molecule are assigned new reaction sequences involving additional internal H atom abstractions not previously allowed. This process accelerates autoignition in fuels with tertiary C-H bonds in the parent fuel. In addition, the rates of hydroperoxyalkylperoxy radical isomerization reactions have all been reduced so that they are now equal to rates of analogous alkylperoxy radical isomerizations, significantly improving agreement between computed and experimental ignition delay times in the rapid compression machine. Computed ignition delay times agree well with experimental results in the few cases where experiments have been carried out for specific heptane isomers, and predictive model calculations are reported for the remaining isomers. The computed results fall into three general groups; the first consists of the most reactive isomers, including n-heptane, 2-methyl hexane and 3-methyl hexane. The second group consists of the least reactive isomers, including 2,2-dimethyl pentane, 3,3-dimethyl pentane, 2,3-dimethyl pentane, 2,4-dimethyl pentane and 2,2,3-trimethyl butane. The remaining isomer, 3-ethyl pentane, was observed computationally to have an intermediate level of reactivity. These observations are generally

  14. Bacterial production of conjugated linoleic and linolenic Acid in foods: a technological challenge.

    PubMed

    Gorissen, Lara; Leroy, Frédéric; De Vuyst, Luc; De Smet, Stefaan; Raes, Katleen

    2015-01-01

    Conjugated linoleic acid (CLA) and conjugated linolenic acid (CLNA) isomers are present in foods derived from ruminants as a result of the respective linoleic acid (LA) and α-linolenic acid (LNA) metabolism by ruminal microorganisms and in animals' tissues. CLA and CLNA have isomer-specific, health-promoting properties, including anticarcinogenic, antiatherogenic, anti-inflammatory, and antidiabetic activity, as well as the ability to reduce body fat. Besides ruminal microorganisms, such as Butyrivibrio fibrisolvens, many food-grade bacteria, such as bifidobacteria, lactic acid bacteria (LAB), and propionibacteria, are able to convert LA and LNA to CLA and CLNA, respectively. Linoleate isomerase activity, responsible for this conversion, is strain-dependent and probably related to the ability of the producer strain to tolerate the toxic effects of LA and LNA. Since natural concentrations of CLA and CLNA in ruminal food products are relatively low to exert their health benefits, food-grade bacteria with linoleate isomerase activity could be used as starter or adjunct cultures to develop functional fermented dairy and meat products with increased levels of CLA and CLNA or included in fermented products as probiotic cultures. However, results obtained so far are below expectations due to technological bottlenecks. More research is needed to assess if bacterial production kinetics can be increased and can match food processing requirements. PMID:24915316

  15. Isomer Shift and Magnetic Moment of the Long-Lived 1 /2+ Isomer in 30,79Zn49: Signature of Shape Coexistence near 78Ni

    NASA Astrophysics Data System (ADS)

    Yang, X. F.; Wraith, C.; Xie, L.; Babcock, C.; Billowes, J.; Bissell, M. L.; Blaum, K.; Cheal, B.; Flanagan, K. T.; Garcia Ruiz, R. F.; Gins, W.; Gorges, C.; Grob, L. K.; Heylen, H.; Kaufmann, S.; Kowalska, M.; Kraemer, J.; Malbrunot-Ettenauer, S.; Neugart, R.; Neyens, G.; Nörtershäuser, W.; Papuga, J.; Sánchez, R.; Yordanov, D. T.

    2016-05-01

    Collinear laser spectroscopy is performed on the 30,79Zn49 isotope at ISOLDE-CERN. The existence of a long-lived isomer with a few hundred milliseconds half-life is confirmed, and the nuclear spins and moments of the ground and isomeric states in 79Zn as well as the isomer shift are measured. From the observed hyperfine structures, spins I =9 /2 and I =1 /2 are firmly assigned to the ground and isomeric states. The magnetic moment μ (79Zn)=-1.1866 (10 )μN , confirms the spin-parity 9 /2+ with a ν g9/2 -1 shell-model configuration, in excellent agreement with the prediction from large scale shell-model theories. The magnetic moment μ (Znm79)=-1.0180 (12 )μN supports a positive parity for the isomer, with a wave function dominated by a 2 h -1 p neutron excitation across the N =50 shell gap. The large isomer shift reveals an increase of the intruder isomer mean square charge radius with respect to that of the ground state, δ ⟨rc2⟩79 ,79 m=+0.204 (6 ) fm2 , providing first evidence of shape coexistence.

  16. Isomer Shift and Magnetic Moment of the Long-Lived 1/2^{+} Isomer in _{30}^{79}Zn_{49}: Signature of Shape Coexistence near ^{78}Ni.

    PubMed

    Yang, X F; Wraith, C; Xie, L; Babcock, C; Billowes, J; Bissell, M L; Blaum, K; Cheal, B; Flanagan, K T; Garcia Ruiz, R F; Gins, W; Gorges, C; Grob, L K; Heylen, H; Kaufmann, S; Kowalska, M; Kraemer, J; Malbrunot-Ettenauer, S; Neugart, R; Neyens, G; Nörtershäuser, W; Papuga, J; Sánchez, R; Yordanov, D T

    2016-05-01

    Collinear laser spectroscopy is performed on the _{30}^{79}Zn_{49} isotope at ISOLDE-CERN. The existence of a long-lived isomer with a few hundred milliseconds half-life is confirmed, and the nuclear spins and moments of the ground and isomeric states in ^{79}Zn as well as the isomer shift are measured. From the observed hyperfine structures, spins I=9/2 and I=1/2 are firmly assigned to the ground and isomeric states. The magnetic moment μ (^{79}Zn)=-1.1866(10)μ_{N}, confirms the spin-parity 9/2^{+} with a νg_{9/2}^{-1} shell-model configuration, in excellent agreement with the prediction from large scale shell-model theories. The magnetic moment μ (^{79m}Zn)=-1.0180(12)μ_{N} supports a positive parity for the isomer, with a wave function dominated by a 2h-1p neutron excitation across the N=50 shell gap. The large isomer shift reveals an increase of the intruder isomer mean square charge radius with respect to that of the ground state, δ⟨r_{c}^{2}⟩^{79,79m}=+0.204(6)  fm^{2}, providing first evidence of shape coexistence. PMID:27203317

  17. Physical chemistry and membrane properties of two phosphatidylinositol bisphosphate isomers.

    PubMed

    Slochower, David R; Wang, Yu-Hsiu; Radhakrishnan, Ravi; Janmey, Paul A

    2015-05-21

    The most highly charged phospholipids, polyphosphoinositides, are often involved in signaling pathways that originate at cell-cell and cell-matrix contacts, and different isomers of polyphosphoinositides have distinct biological functions that cannot be explained by separate highly specific protein ligand binding sites [Lemmon, Nat. Rev. Mol. Cell Biol., 2008, 9, 99-111]. PtdIns(3,5)P2 is a low abundance phosphoinositide localized to cytoplasmic-facing membrane surfaces, with relatively few known ligands, yet PtdIns(3,5)P2 plays a key role in controlling membrane trafficking events and cellular stress responses that cannot be duplicated by other phosphoinositides [Dove et al., Nature, 1997, 390, 187-192; Michell, FEBS J., 2013, 280, 6281-6294]. Here we show that PtdIns(3,5)P2 is structurally distinct from PtdIns(4,5)P2 and other more common phospholipids, with unique physical chemistry. Using multiscale molecular dynamics techniques on the quantum level, single molecule, and in bilayer settings, we found that the negative charge of PtdIns(3,5)P2 is spread over a larger area, compared to PtdIns(4,5)P2, leading to a decreased ability to bind divalent ions. Additionally, our results match well with experimental data characterizing the cluster forming potential of these isomers in the presence of Ca(2+) [Wang et al., J. Am. Chem. Soc., 2012, 134, 3387-3395; van den Bogaart et al., Nature, 2011, 479, 552-555]. Our results demonstrate that the different cellular roles of PtdIns(4,5)P2 and PtdIns(3,5)P2in vivo are not simply determined by their localization by enzymes that produce or degrade them, but also by their molecular size, ability to chelate ions, and the partial dehydration of those ions, which might affect the ability of PtdIns(3,5)P2 and PtdIns(4,5)P2 to form phosphoinositide-rich clusters in vitro and in vivo. PMID:25901568

  18. Interaction of Boron-Nitrogen Doped Benzene Isomers with Water.

    PubMed

    Yourdkhani, Sirous; Chojecki, Michał; Hapka, Michał; Korona, Tatiana

    2016-08-11

    The interaction of 1,2-dihydro-1,2-, 1,3-dihydro-1,3- and 1,4-dihydro-1,4-azaborine isomers with one and two water molecules has been studied using a variety of supermolecular (Møller-Plesset = MP, and coupled cluster = CC) as well as perturbational (symmetry-adapted perturbation theory = SAPT) electron-correlation methods in the complete basis-set limit. It has been found that the water molecule binds to azaborine isomers through O-H···π, π-H···O, and dihydrogen bonding linkages. The SAPT interaction energy decomposition shows that these complexes are mostly stabilized by dispersion followed closely by induction contributions. Pauli repulsion hinders water molecule to be polarized by azaborine in the O-H···π type of complexes. According to the interacting-quantum-atoms analysis, the structures with a primary binding of the O-H···π type benefit from an additional stabilization factor resulting from the interaction of the oxygen and the second hydrogen atom of water, i.e., the one which does not point toward the ring, while the interaction of hydrogens from water with azaborines plays a destabilizing role for the π-H···O type. The same method states that the intermolecular bindings between azaborines and the water molecule have a multicenter character with a small bond polarization, and they are classified as closed-shell (noncovalent) by quantum theory of atoms-in-molecules analysis at bond critical points. The complexes of azaborines with two water molecules tend to arrange in a circular fashion with a recognizable water dimer attached to the azaborine molecule. A comparison with the CCSD(T) benchmarks shows that the nonadditive contribution to the interaction energy of the trimers is negative and with a good accuracy can be accounted for by the MP2 method. A good agreement between Hartree-Fock (HF) and MP2 nonadditive energy, as well as the decomposition of HF nonadditive interaction energies divulge the importance of nonadditive induction

  19. Necessary conditions for the photogeneration of nitrosyl linkage isomers.

    PubMed

    Schaniel, Dominik; Woike, Theo

    2009-06-01

    We investigate the fundamental necessary conditions for optical generation of nitrosyl linkage isomers in ML(5)NO compounds (M = transition metal, L arbitrary ligand) on the examples of K(3)[Mn(CN)(5)NO].2H(2)O and Na(2)[Fe(CN)(5)NO].2H(2)O. We show that the NO linkage isomers of the side-on bonded type (SII, 90 degrees rotation of NO) and of the isonitrosyl type M-ON, where NO is O-bound to the metal M (SI, 180 degrees rotation of NO), can be generated if two conditions are fullfilled. First the optical excitation must lead to a change in the bond between the NO group and the central metal atom M, either by a metal-to-ligand charge transfer of type d -->pi*(NO) or by a d-->d(z(2)) transition, which changes the sigma bonding of the NO group to the metal, such that the vibrational deformation mode delta(M-N-O) can drive the system into the SII configuration. Second the excited state potential must posses a minimum close to the saddle point of the ground state surface between GS and SII, SI, or cross that surface, such that the relaxation from the excited state into the metastable minima can occur. The same is true for transfers between the two metastable states SII and SI. As a further constraint with respect to the amount of population, i.e. the number of complexes which can be transferred into SII or SI, the cross sections sigma(GS,SII,SI) of the states GS, SII, and SI must be considered. If sigma(GS) > sigma(SII) and sigma(SI) > sigma(SII) SII can be occupied while SI can be significantly occupied if sigma(GS) > sigma(SI) and sigma(SII) > sigma(SI). More simply speaking the depletion rate of the metastable state should be smaller than its population rate for a given wavelength. PMID:19458843

  20. Stereocontrolled synthesis of the four 16-hydroxymethyl-19-nortestosterone isomers and their antiproliferative activities.

    PubMed

    Schneider, Gyula; Kiss, Anita; Mernyák, Erzsébet; Benke, Zsanett; Wölfling, János; Frank, Éva; Bózsity, Noémi; Gyovai, András; Minorics, Renáta; Zupkó, István

    2016-01-01

    Novel 16-hydroxymethyl-19-nortestosterone diastereomers were prepared by Birch reduction from the corresponding 3-methoxy-16-hydroxymethylestra-1,3,5(10)-trien-17-ol isomers with known configurations. The synthesized compounds are 16α- and 16β-hydroxymethyl-substituted 19-nortestosterone and their 17α-epimers. To prepare 17α-19-nortestosterone, the Mitsunobu inversion reaction of 19-nortestosterone with different alkyl and aryl carboxylic acids was chosen. Deacylation of the new compounds by the Zemplén method yielded the required 17α-19-nortestosterone. The antiproliferative activities of the structurally related compounds were determined in vitro through microculture tetrazolium assays on a panel of human adherent cervical (HeLa, SiHa and C33A), breast (MCF-7, MDA-MB-231, MDA-MB-361 and T47D) and ovarian (A2780) cell lines. The 17α epimer of 19-nortestosterone demonstrated considerable activity, selectively for HeLa cells, with a calculated IC50 of 0.65 μM. The reference compound, cisplatin, displayed an order of magnitude higher IC50 (12.4 μM). The cancer selectivity of 17α-19-nortestosterone was tested by MTT assay performed with noncancerous human fibroblast cell line MRC-5. The results indicated that 17α-19-nortestosterone selectively disturbs the viability of HeLa cells without greatly affecting other cancer cell types and intact fibroblasts. PMID:26686898

  1. Ab initio quantum chemical investigation of several isomers of anionic Si 6

    NASA Astrophysics Data System (ADS)

    Takahashi, Masae; Kawazoe, Yoshiyuki

    2006-02-01

    Eight isomers (planar hexagon, benzvalene, Dewar benzene, triangular prismane, bicyclopropenyl, octahedron, chair form, and twist boat form) of Si 6, Si62-, Si64-, and Si66-, have been searched for by the MP2 and B3LYP electronic structure calculations. Totally 14 isomers were found: two Si 6, six Si62-, five Si64-, and one Si66-. Two of them are different from the eight isomers: deformed triangle Si62-; pentagonal pyramidal Si64-. We discovered that the predicted stable shapes of Si62-, Si64-, and Si66- are octahedral, pentagonal pyramidal, and hexagonal, respectively, which agrees well with Wade rule.

  2. Theoretical studies of possible toroidal high-spin isomers in the light-mass region

    DOE PAGESBeta

    Staszczak, A.; Wong, Cheuk-Yin

    2016-05-11

    We review our theoretical knowledge of possible toroidal high-spin isomers in the light mass region in 28 A 52 obtained previously in cranked Skyrme-Hartree-Fock calculations. We report additional toroidal high-spin isomers in 56Ni with I=114 and 140, which follow the same (multi-particle) (multi-hole) systematics as other toroidal high-spin isomers. We examine the production of these exotic nuclei by fusion of various projectiles on 20Ne or 28Si as an active target in time-projection-chamber (TPC) experiments.

  3. Effects of high-order deformation on high-K isomers in superheavy nuclei

    SciTech Connect

    Liu, H. L.; Bertulani, C. A.; Xu, F. R.; Walker, P. M.

    2011-01-15

    Using, for the first time, configuration-constrained potential-energy-surface calculations with the inclusion of {beta}{sub 6} deformation, we find remarkable effects of the high-order deformation on the high-K isomers in {sup 254}No, the focus of recent spectroscopy experiments on superheavy nuclei. For shapes with multipolarity six, the isomers are more tightly bound and, microscopically, have enhanced deformed shell gaps at N=152 and Z=100. The inclusion of {beta}{sub 6} deformation significantly improves the description of the very heavy high-K isomers.

  4. Controlling the Excited-State Dynamics of Nuclear Spin Isomers Using the Dynamic Stark Effect.

    PubMed

    Waldl, Maria; Oppel, Markus; González, Leticia

    2016-07-14

    Stark control of chemical reactions uses intense laser pulses to distort the potential energy surfaces of a molecule, thus opening new chemical pathways. We use the concept of Stark shifts to convert a local minimum into a local maximum of the potential energy surface, triggering constructive and destructive wave-packet interferences, which then induce different dynamics on nuclear spin isomers in the electronically excited state of a quinodimethane derivative. Model quantum-dynamical simulations on reduced dimensionality using optimized ultrashort laser pulses demonstrate a difference of the excited-state dynamics of two sets of nuclear spin isomers, which ultimately can be used to discriminate between these isomers. PMID:26840424

  5. Theoretical studies of possible toroidal high-spin isomers in the light-mass region

    NASA Astrophysics Data System (ADS)

    Staszczak, Andrzej; Wong, Cheuk-Yin

    2016-05-01

    We review our theoretical knowledge of possible toroidal high-spin isomers in the light mass region in 28≤A≤52 obtained previously in cranked Skyrme-Hartree-Fock calculations. We report additional toroidal high-spin isomers in 56Ni with I=114ħ and 140ħ, which follow the same (multi-particle)-(multi-hole) systematics as other toroidal high-spin isomers. We examine the production of these exotic nuclei by fusion of various projectiles on 20Ne or 28Si as an active target in time-projection-chamber (TPC) experiments.

  6. Identification/quantification of free and bound phenolic acids in peel and pulp of apples (Malus domestica) using high resolution mass spectrometry (HRMS).

    PubMed

    Lee, Jihyun; Chan, Bronte Lee Shan; Mitchell, Alyson E

    2017-01-15

    Free and bound phenolic acids were measured in the pulp and peel of four varieties of apples using high resolution mass spectrometry. Twenty-five phenolic acids were identified and included: 8 hydroxybenzoic acids, 11 hydroxycinnamic acids, 5 hydroxyphenylacetic acids, and 1 hydoxyphenylpropanoic acid. Several phenolics are tentatively identified for the first time in apples and include: methyl gallate, ethyl gallate, hydroxy phenyl acetic acid, three phenylacetic acid isomers, 3-(4-hydroxyphenyl)propionic acid, and homoveratric acid. With exception of chlorogenic and caffeic acid, most phenolic acids were quantified for the first time in apples. Significant varietal differences (p<0.05) were observed in both peel and pulp. The levels of total phenolic acids were higher in the pulp as compared to apple peel (dry weight) in all varieties. Coumaroylquinic, protocatechuic, 4-hydroxybenzoic, vanillic and t-ferulic acids were present in free forms. With exception of chlorogenic acid, all other phenolic acids were present only as bound forms. PMID:27542479

  7. Mannosylation Allows for Synergic (CD44/C-Type Lectin) Uptake of Hyaluronic Acid Nanoparticles in Dendritic Cells, but Only upon Correct Ligand Presentation.

    PubMed

    Gennari, Arianna; Pelliccia, Maria; Donno, Roberto; Kimber, Ian; Tirelli, Nicola

    2016-04-01

    The selective targeting of dendritic cells (DCs) can lead to more efficacious vaccines. Here, materials have been designed for a synergic DC targeting: interacting with CD44 through the use of hyaluronic acid (HA), and with mannose-binding lectins (typical DC pattern recognition receptors) through HA mannosylation. Negatively charged, HA-displaying nanoparticles are produced via polyelectrolyte complexation of (mannosylated) HA and high- or low- molecular-weight chitosan (CS, 36 and 656 kDa). Using CS36, HA is better exposed and the particles have a higher affinity for HA receptors; this means a higher number of receptors clustered around each particle and, due to the rather limited CD44 availability, an overall lower uptake per cell. Employing Langerhans-like XS106 cells, all particles show negligible toxicity or inflammatory activation. The cellular uptake kinetics are qualitatively similar to other leukocytic models and thus considered to be CD44-dominated; the uptake increases with increasing HA mannosylation and with the use of adjuvants (LPS, mannan) for CS36/HA but not for CS656//HA particles; this indicates that the interactions with mannose-binding receptors requires a correct ligand presentation, and only in that case can they be enhanced by appropriate adjuvants. In summary, mannose-binding receptors can be used to enhance the internalization of HA-based carriers, although this positive synergy depends on the mode of ligand presentation. PMID:26865006

  8. The quantitative spectrum of inositol phosphate metabolites in avian erythrocytes, analysed by proton n.m.r. and h.p.l.c. with direct isomer detection.

    PubMed Central

    Radenberg, T; Scholz, P; Bergmann, G; Mayr, G W

    1989-01-01

    The spectrum of inositol phosphate isomers present in avian erythrocytes was investigated in qualitative and quantitative terms. Inositol phosphates were isolated in micromolar quantities from turkey blood by anion-exchange chromatography on Q-Sepharose and subjected to proton n.m.r. and h.p.l.c. analysis. We employed a h.p.l.c. technique with a novel, recently described complexometric post-column detection system, called 'metal-dye detection' [Mayr (1988) Biochem. J. 254, 585-591], which enabled us to identify non-radioactively labelled inositol phosphate isomers and to determine their masses. The results indicate that avian erythrocytes contain the same inositol phosphate isomers as mammalian cells. Denoted by the 'lowest-locant rule' [NC-IUB Recommendations (1988) Biochem. J. 258, 1-2] irrespective of true enantiomerism, these are Ins(1,4)P2, Ins(1,6)P2, Ins(1,3,4)P3, Ins(1,4,5)P3, Ins(1,3,4,5)P4, Ins(1,3,4,6)P4, Ins(1,4,5,6)P4, Ins(1,3,4,5,6)P5, and InsP6. Furthermore, we identified two inositol trisphosphate isomers hitherto not described for mammalian cells, namely Ins(1,5,6)P3 and Ins(2,4,5)P3. The possible position of these two isomers in inositol phosphate metabolism and implications resulting from absolute abundances of inositol phosphates are discussed. PMID:2604720

  9. Ab initio SCF calculations on hydrogen bonded cresol isomers

    NASA Astrophysics Data System (ADS)

    Pohl, M.; Kleinermanns, K.

    1988-12-01

    Ab initio GAUSSIAN 80 calculations with two different basis sets (STO-3G and 4 31 G*) were performed on hydrogen bonded cresol isomers for comparison with experimental data from free jet fluorescence excitation spectroscopy. For m-cresol, the calculated barriers for hindered internal rotation of the OH-group and the CH3-group are in good agreement with experiment. The calculations show the trans-linear configuration of p-cresol· B-clusters ( B = H2O, CH3OH) to be more stable than the all-planar configuration. This agrees with CI calculations and microwave spectroscopic investigations of the water dimer. Calculations of both the intermolecular stretch and bend frequencies of p-cresol· B-clusters show little dependence on the all-planar or trans-linear configuration but a strong dependence on the choice of the basis set. With the minimal basis set STO-3G, the vibrational energies are generally too high. The agreement between the calculated vibrational frequencies from the 4 31 G* basis set and the experimental values is fair.

  10. Products from the Oxidation of Linear Isomers of Hexene

    PubMed Central

    Battin-Leclerc, Frédérique; Rodriguez, Anne; Husson, Benoit; Herbinet, Olivier; Glaude, Pierre-Alexandre; Wang, Zhandong; Cheng, Zhanjun; Qi, Fei

    2014-01-01

    The experimental study of the oxidation of the three linear isomers of hexene was performed in a quartz isothermal jet-stirred reactor (JSR) at temperatures ranging from 500 to 1100 K including the negative temperature coefficient (NTC) zone, at quasi-atmospheric pressure (1.07 bar), at a residence time of 2 s and with dilute stoichiometric mixtures. The fuel and reaction product mole fractions were measured using online gas chromatography. In the case of 1-hexene, the JSR has also been coupled through a molecular-beam sampling system to a reflectron time-of-flight mass spectrometer combined with tunable synchrotron vacuum ultraviolet photoionization. A difference of reactivity between the three fuels which varies with the temperature range has been observed and is discussed according to the changes in the possible reaction pathways when the double bond is displaced. An enhanced importance of the reactions via the Waddington mechanism and of those of allylic radicals with HO2 radicals can be noted for 2- and 3-hexenes compared to 1-hexene. PMID:24400665

  11. The nucleotide sequence of HLA-B{sup *}2704 reveals a new amino acid substitution in exon 4 which is also present in HLA-B{sup *}2706

    SciTech Connect

    Rudwaleit, M.; Bowness, P.; Wordsworth, P.

    1996-12-31

    The HLA-B27 subtype HLA-B{sup *}2704 is virtually absent in Caucasians but common in Orientals, where it is associated with ankylosing spondylitis. The amino acid sequence of HLA-B{sup *}2704 has been established by peptide mapping and was shown to differ by two amino acids from HLA-B{sup *}2705, HLA-B{sup *}2704 is characterized by a serine for aspartic acid substitution at position 77 and glutamic acid for valine at position 152. To date, however, no nucleotide sequence confirming these changes at the DNA level has been published. 13 refs., 2 figs.

  12. Voltammetric analysis with the use of a novel electro-polymerised graphene-nafion film modified glassy carbon electrode: simultaneous analysis of noxious nitroaniline isomers.

    PubMed

    Lin, Xiaoyun; Ni, Yongnian; Kokot, Serge

    2012-12-01

    A new modified electrode was constructed by the electro-polymerization of 7-[(2,4-dihydroxy-5-carboxybenzene)azo]-8-hydroxyquinoline-5-sulfonic acid (DHCBAQS) at a graphene-nafion modified glassy carbon electrode (GCE). The construction process was performed stepwise and at each step the electrochemical characteristics were investigated particularly with respect to the oxidation of the three noxious analytes, 2-nitroaniline (2-NA), 3-nitroaniline (3-NA), 4-nitroaniline (4-NA); the electrode treated with the fluorescence reagent DHCBAQS performed best. At this electrode, the differential pulse voltammetry peak currents of the three isomers increased linearly with their concentrations in the range of 0.05-0.60 μg mL(-1), respectively, and their corresponding limits of detection (LODs) were all about 0.022 μg mL(-1). Furthermore, satisfactory results were obtained when this electrode was applied for the simultaneous quantitative analysis of the nitroaniline isomer mixtures by Principal component regression (PCR) and Partial least squares (PLS) as calibration methods (relative prediction error (PRE(T)) - 9.04% and 9.23%) and average recoveries (101.0% and 101.7%), respectively. The above novel poly-DHCBAQS/graphene-nafion/GCE was successfully employed for the simultaneous analysis of the three noxious nitroaniline isomers in water and sewage samples. PMID:23142057

  13. Identification of Geometrical Isomers of the Cobalt(III)-Iminodiacetate System.

    ERIC Educational Resources Information Center

    Lawrance, Geoffrey A.; Rix, Colin J.

    1979-01-01

    In this experiment, students prepare, isolate, and characterize two geometrical isomers of a metal coordination compound. This experiment provides a good introduction to the techniques of modern coordination chemistry. (BB)

  14. 40 CFR 180.1103 - Isomate-C; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... moth pheromone (Isomate-C) E,E-8,10-dodecenyl alcohol, dodecanol, tetradecanol is exempt from the requirements of a tolerance in or on all raw agricultural commodities when formulated in polyethylene...

  15. 40 CFR 180.1103 - Isomate-C; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... moth pheromone (Isomate-C) E,E-8,10-dodecenyl alcohol, dodecanol, tetradecanol is exempt from the requirements of a tolerance in or on all raw agricultural commodities when formulated in polyethylene...

  16. 40 CFR 180.1103 - Isomate-C; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... moth pheromone (Isomate-C) E,E-8,10-dodecenyl alcohol, dodecanol, tetradecanol is exempt from the requirements of a tolerance in or on all raw agricultural commodities when formulated in polyethylene...

  17. 40 CFR 180.1103 - Isomate-C; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... moth pheromone (Isomate-C) E,E-8,10-dodecenyl alcohol, dodecanol, tetradecanol is exempt from the requirements of a tolerance in or on all raw agricultural commodities when formulated in polyethylene...

  18. 40 CFR 180.1103 - Isomate-C; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... moth pheromone (Isomate-C) E,E-8,10-dodecenyl alcohol, dodecanol, tetradecanol is exempt from the requirements of a tolerance in or on all raw agricultural commodities when formulated in polyethylene...

  19. Structure of three-quasiparticle isomers in {sup 169}Ho and {sup 171}Tm

    SciTech Connect

    Dracoulis, G. D.; Lane, G. J.; Hughes, R. O.; Kondev, F. G.; Chiara, C. J.; Watanabe, H.; Seweryniak, D.; Zhu, S.; Carpenter, M. P.; Janssens, R. V. F.; Lauritsen, T.; Lister, C. J.; McCutchan, E. A.; Stefanescu, I.; Chowdhury, P.

    2010-09-15

    A three-quasiparticle isomer with {tau}=170(8) {mu}s and K{sup {pi}=} (19/2{sup +}) has been identified in the neutron-rich isotope {sup 169}Ho. The isomer decays with K-forbidden transitions to members of a band associated with the 7/2{sup -}[523] proton configuration, whose structure is characterized through analysis of the in-band {gamma}-ray branching ratios. In the isotone {sup 171}Tm, the rotational band based on the known 19/2{sup +}, three-quasiparticle isomer has also been observed. Alternative one-proton two-neutron configurations for the isomer in {sup 169}Ho are discussed in terms of multiquasiparticle calculations and through a comparison with the structures observed in {sup 171}Tm.

  20. Simple Nuclear Structure in (111-129)Cd from Atomic Isomer Shifts.

    PubMed

    Yordanov, D T; Balabanski, D L; Bissell, M L; Blaum, K; Budinčević, I; Cheal, B; Flanagan, K; Frömmgen, N; Georgiev, G; Geppert, Ch; Hammen, M; Kowalska, M; Kreim, K; Krieger, A; Meng, J; Neugart, R; Neyens, G; Nörtershäuser, W; Rajabali, M M; Papuga, J; Schmidt, S; Zhao, P W

    2016-01-22

    Isomer shifts have been determined in ^{111-129}Cd by high-resolution laser spectroscopy at CERN-ISOLDE. The corresponding mean square charge-radii changes, from the 1/2^{+} and the 3/2^{+} ground states to the 11/2^{-} isomers, have been found to follow a distinct parabolic dependence as a function of the atomic mass number. Since the isomers have been previously associated with simplicity due to the linear mass dependence of their quadrupole moments, the regularity of the isomer shifts suggests a higher order of symmetry affecting the ground states in addition. A comprehensive description assuming nuclear deformation is found to accurately reproduce the radii differences in conjunction with the known quadrupole moments. This intuitive interpretation is supported by covariant density functional theory. PMID:26849588