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Sample records for acid oxidation defects

  1. Mitochondrial fatty acid oxidation defects--remaining challenges

    DEFF Research Database (Denmark)

    Gregersen, Niels; Andresen, Brage S; Pedersen, Christina B;

    2008-01-01

    Mitochondrial fatty acid oxidation defects have been recognized since the early 1970s. The discovery rate has been rather constant, with 3-4 'new' disorders identified every decade and with the most recent example, ACAD9 deficiency, reported in 2007. In this presentation we will focus on three...... of different mitochondrial dehydrogenases as well as deficiency of FAD and coenzyme Q(10). With SCAD deficiency, the challenge is to elucidate whether ACADS gene variations are disease-associated, especially when combined with other genetic/cellular/environmental factors, which may act synergistically....

  2. Defects at oxide surfaces

    CERN Document Server

    Thornton, Geoff

    2015-01-01

    This book presents the basics and characterization of defects at oxide surfaces. It provides a state-of-the-art review of the field, containing information to the various types of surface defects, describes analytical methods to study defects, their chemical activity and the catalytic reactivity of oxides. Numerical simulations of defective structures complete the picture developed. Defects on planar surfaces form the focus of much of the book, although the investigation of powder samples also form an important part. The experimental study of planar surfaces opens the possibility of applying the large armoury of techniques that have been developed over the last half-century to study surfaces in ultra-high vacuum. This enables the acquisition of atomic level data under well-controlled conditions, providing a stringent test of theoretical methods. The latter can then be more reliably applied to systems such as nanoparticles for which accurate methods of characterization of structure and electronic properties ha...

  3. Refsum disease: a defect in the alpha-oxidation of phytanic acid in peroxisomes.

    Science.gov (United States)

    Singh, I; Pahan, K; Singh, A K; Barbosa, E

    1993-10-01

    The oxidation of phytanic acid to pristanic acid was previously demonstrated to be deficient in monolayer cultures of skin fibroblasts (Herndon et al. 1969. J. Clin. Invest. 48: 1017-1032). However, identification of subcellular organelle with deficient enzyme activity has not been established. To define the subcellular organelle with deficient enzyme activity in the catabolism of phytanic acid, we measured the oxidation of [1-14C] phytanic acid to 14CO2 and pristanic acid in different subcellular organelles isolated from cultured skin fibroblasts from control and Refsum patients. The rates of oxidation of phytanic acid in peroxisomes, mitochondria, and endoplasmic reticulum were 37.1 +/- 2.65, 1.9 +/- 0.3, and 0.4 +/- 0.07 pmol/h per mg protein, respectively, from control fibroblasts. The phytanic acid oxidation activity in mitochondria (2.04 +/- 0.7 pmol/h per mg protein) and endoplasmic reticulum (0.43 +/- 0.2 pmol/h per mg protein) from Refsum fibroblasts was similar to control fibroblasts. However, phytanic acid oxidation in peroxisomes from Refsum fibroblasts was not detected at all the protein concentrations tested. On the other hand, the peroxisomes from Refsum fibroblasts had normal rates of activation and oxidation of palmitic and lignoceric acids, suggesting that the peroxisomes isolated from Refsum fibroblasts were metabolically active. The phytanoyl-CoA ligase, the first enzyme in the alpha-oxidation pathway, had activity similar to that in peroxisomes from control (9.86 +/- 0.09 nmol/h per mg protein) and Refsum (10.25 +/- 0.31 nmol/h per mg protein) fibroblasts. The data described here clearly demonstrate that pathognomonic accumulation of phytanic acid in patients with Refsum disease is due to the deficient activity of peroxisomal alpha-oxidation enzyme system.

  4. Phytanic acid oxidation: normal activation and transport yet defective alpha-hydroxylation of phytanic acid in peroxisomes from Refsum disease and rhizomelic chondrodysplasia punctata.

    Science.gov (United States)

    Pahan, K; Khan, M; Singh, I

    1996-05-01

    In humans the oxidation of phytanic acid is a peroxisomal function. To understand the possible mechanisms for the pathognomic accumulation of phytanic acid in plasma and body fluids of Refsum disease (RD) and rhizomelic chondrodysplasia punctata (RCDP), we investigated activities of various steps (activation, transport, and oxidation) in the metabolism of phytanic acid in peroxisomes isolated from cultured skin fibroblasts from control, RD, and RCDP subjects. Activation of phytanic acid was normal in peroxisomes from both RD and RCDP. Transport of phytanic acid or phytanoyl-CoA in the absence or presence of fatty acid activating cofactors (ATP, MgCl2, and CoASH) into peroxisomes isolated from RD and RCDP skin fibroblasts was also similar to that of peroxisomes from control fibroblasts. Defective oxidation of [(2,3)-3H]- or [1-14C]phytanic acid, or [1-14C]phytanoyl-CoA (substrate for the first step of alpha-oxidation) but normal oxidation of [1-14C] alpha-hydroxyphytanic acid (substrate for the second step of the alpha-oxidation pathway) in peroxisomes from RD clearly demonstrates that excessive accumulation of phytanic acid in plasma and body fluids of RD is due to the deficiency of phytanic acid alpha-hydroxylase in peroxisomes. However, in RCDP peroxisomes, in addition to deficient oxidation of [1-14C]phytanic acid or phytanoyl-CoA or [(2,3)-3H]phytanic acid, the oxidation of [1-14C] alpha-hydroxyphytanic acid was also deficient, indicating that in RCDP the activities both of alpha-hydroxylation of phytanic acid and decarboxylation of alpha-hydroxyphytanic acid are deficient. These observations indicate that peroxisomal membrane functions (phytanic acid activation and transport) in phytanic acid metabolism are normal in both RD and RCDP. The defect in RD is in the alpha-hydroxylation of phytanic acid; whereas in RCDP both alpha-hydroxylation of phytanic acid as well as decarboxylation of alpha-hydroxyphytanic acid are deficient.

  5. Thyroid hormone reverses aging-induced myocardial fatty acid oxidation defects and improves the response to acutely increased afterload.

    Directory of Open Access Journals (Sweden)

    Dolena Ledee

    Full Text Available BACKGROUND: Subclinical hypothyroidism occurs during aging in humans and mice and may contribute to the development of heart failure. Aging also impairs myocardial fatty acid oxidation, causing increased reliance on flux through pyruvate dehydrogenase (PDH to maintain function. We hypothesize that the metabolic changes in aged hearts make them less tolerant to acutely increased work and that thyroid hormone supplementation reverses these defects. METHODS: Studies were performed on young (Young, 4-6 months and aged (Old, 22-24 months C57/BL6 mice at standard (50 mmHg and high afterload (80 mmHg. Another aged group received thyroid hormone for 3 weeks (Old-TH, high afterload only. Function was measured in isolated working hearts along with substrate fractional contributions (Fc to the citric acid cycle (CAC using perfusate with (13C labeled lactate, pyruvate, glucose and unlabeled palmitate and insulin. RESULTS: Old mice maintained cardiac function under standard workload conditions, despite a marked decrease in unlabeled (presumably palmitate Fc and relatively similar individual carbohydrate contributions. However, old mice exhibited reduced palmitate oxidation with diastolic dysfunction exemplified by lower -dP/dT. Thyroid hormone abrogated the functional and substrate flux abnormalities in aged mice. CONCLUSION: The aged heart shows diminished ability to increase cardiac work due to substrate limitations, primarily impaired fatty acid oxidation. The heart accommodates slightly by increasing efficiency through oxidation of carbohydrate substrates. Thyroid hormone supplementation in aged mice significantly improves cardiac function potentially through restoration of fatty acid oxidation.

  6. Metabolic encephalopathy and lipid storage myopathy associated with a presumptive mitochondrial fatty acid oxidation defect in a dog

    Directory of Open Access Journals (Sweden)

    Vanessa R Biegen

    2015-11-01

    Full Text Available A 1-year-old spayed female Shih Tzu presented for episodic abnormalities of posture and mentation. Neurologic examination was consistent with a bilaterally symmetric multifocal encephalopathy. The dog had a waxing-and-waning hyperlactemia and hypoglycemia. Magnetic resonance imaging revealed bilaterally symmetric cavitated lesions of the caudate nuclei with less severe abnormalities in the cerebellar nuclei. Empirical therapy was unsuccessful and the patient was euthanized. Post-mortem histopathology revealed bilaterally symmetric necrotic lesions of the caudate and cerebellar nuclei and multi-organ lipid accumulation, including a lipid storage myopathy. Malonic aciduria and ketonuria were found on urinary organic acid screen. Plasma acylcarnitine analysis suggested a fatty acid oxidation defect. Fatty acid oxidation disorders are inborn errors of metabolism documented in humans, but poorly described in dogs. Although neurologic signs have been described in humans with this group of diseases, descriptions of advanced imaging and histopathology are severely lacking. This report suggests that abnormalities of fatty acid metabolism may cause severe, bilateral gray matter necrosis and lipid accumulation in multiple organs including the skeletal muscles, liver, and kidneys. Veterinarians should be aware that fatty acid oxidation disorders, although potentially fatal, may be treatable. A timely definitive diagnosis is essential in guiding therapy.

  7. Defects in muscle branched-chain amino acid oxidation contribute to impaired lipid metabolism

    DEFF Research Database (Denmark)

    Lerin, Carles; Goldfine, Allison B; Boes, Tanner;

    2016-01-01

    OBJECTIVE: Plasma levels of branched-chain amino acids (BCAA) are consistently elevated in obesity and type 2 diabetes (T2D) and can also prospectively predict T2D. However, the role of BCAA in the pathogenesis of insulin resistance and T2D remains unclear. METHODS: To identify pathways related t...... catabolism may contribute to the development of insulin resistance by perturbing both amino acid and fatty acid metabolism and suggest that targeting BCAA metabolism may hold promise for prevention or treatment of T2D....... methylmalonyl-CoA mutase (Mut) and assessed the effects of altered BCAA flux on lipid and glucose homeostasis. RESULTS: Our data demonstrate perturbed BCAA metabolism and fatty acid oxidation in muscle from insulin resistant humans. Experimental alterations in BCAA flux in cultured cells similarly modulate...... fatty acid oxidation. Mut heterozygosity in mice alters muscle lipid metabolism in vivo, resulting in increased muscle triglyceride accumulation, increased plasma glucose, hyperinsulinemia, and increased body weight after high-fat feeding. CONCLUSIONS: Our data indicate that impaired muscle BCAA...

  8. A Comprehensive Study of Formic Acid Oxidation on Palladium Nanocrystals with Different Types of Facets and Twin Defects

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Sang; Herron, Jeffrey A.; Scaranto, Jessica; Huang, Hongwen; Wang, Yi; Xia, Xiaohu; Lv, Tian; Park, Jinho; Peng, Hsin-Chieh; Mavrikakis, Manos; Xia, Younan

    2015-07-13

    Palladium has been recognized as the best anodic, monometallic electrocatalyst for the formic acid oxidation (FAO) reaction in a direct formic acid fuel cell. Here we report a systematic study of FAO on a variety of Pd nanocrystals, including cubes, right bipyramids, octahedra, tetrahedra, decahedra, and icosahedra. These nanocrystals were synthesized with approximately the same size, but different types of facets and twin defects on their surfaces. Our measurements indicate that the Pd nanocrystals enclosed by {1 0 0} facets have higher specific activities than those enclosed by {1 1 1} facets, in agreement with prior observations for Pd single-crystal substrates. If comparing nanocrystals predominantly enclosed by a specific type of facet, {1 0 0} or {1 1 1}, those with twin defects displayed greatly enhanced FAO activities compared to their single-crystal counterparts. To rationalize these experimental results, we performed periodic, self-consistent DFT calculations on model single-crystal substrates of Pd, representing the active sites present in the nanocrystals used in the experiments. The calculation results suggest that the enhancement of FAO activity on defect regions, represented by Pd(2 1 1) sites, compared to the activity of both Pd(1 0 0) and Pd(1 1 1) surfaces, could be attributed to an increased flux through the HCOO-mediated pathway rather than the COOH-mediated pathway on Pd(2 1 1). Since COOH has been identified as a precursor to CO, a site-poisoning species, a lower coverage of CO at the defect regions will lead to a higher activity for the corresponding nanocrystal catalysts, containing those defect regions.

  9. THYROID HORMONE REVERSES AGING-INDUCED MYOCARDIAL FATTY ACID OXIDATION DEFECTS AND IMPROVES THE RESPONSE TO ACUTELY INCREASED AFTERLOAD

    Energy Technology Data Exchange (ETDEWEB)

    Ledee, Dolena; Portman, Michael A.; Kajimoto, Masaki; Isern, Nancy G.; Olson, Aaron

    2013-06-07

    Background: Subclinical hypothyroidism occurs during aging in humans and mice and may contribute to development of heart failure. Aging also impairs myocardial fatty acid oxidation, causing increased reliance on flux through pyruvate dehydrogenase (PDH) to maintain function. We hypothesize that the metabolic changes in aged hearts make them less tolerant to acutely increased work and that thyroid hormone reverses these defects. Methods: Studies were performed on young (Young, 4-6 months) and aged (Old, 22-24 months) C57/BL6 mice at standard (50 mmHg) and high afterload (80 mmHg). Another aged group received thyroid hormone for 3 weeks (Old-TH, high afterload only). Function was measured in isolated working hearts along with substrate fractional contributions (Fc) to the citric acid cycle (CAC) using perfusate with 13C labeled lactate, pyruvate, glucose and unlabeled palmitate and insulin. Results: Cardiac function was similar between Young and Old mice at standard afterload. Palmitate Fc was reduced but no individual carbohydrate contributions differed. CAC and individual substrate fluxes decreased in aged. At high afterload, -dP/dT was decreased in Old versus Young. Similar to low afterload, palmitate Fc was decreased in Old. Thyroid hormone reversed aging-induced changes in palmitate Fc and flux while significantly improving cardiac function. Conclusion: The aged heart shows diminished ability to increase cardiac work due to substrate limitations, primarily impaired fatty acid oxidation. The heart accommodates slightly by increasing efficiency through oxidation of carbohydrate substrates. Thyroid hormone supplementation in aged mice significantly improves cardiac function potentially through restoration of fatty acid oxidation.

  10. Genetic defects in fatty acid beta-oxidation and acyl-CoA dehydrogenases. Molecular pathogenesis and genotype-phenotype relationships

    DEFF Research Database (Denmark)

    Gregersen, Niels; Bross, Peter; Andresen, Brage S

    2004-01-01

    Mitochondrial fatty acid oxidation deficiencies are due to genetic defects in enzymes of fatty acid beta-oxidation and transport proteins. Genetic defects have been identified in most of the genes where nearly all types of sequence variations (mutation types) have been associated with disease......, stability and kinetic properties for this variant enzyme will be discussed in detail and used as a paradigm for the study of other mis-sense variant proteins. We conclude that the total effect of mis-sense sequence variations may comprise an invariable--sequence variation specific--effect on the catalytic...

  11. Defects in muscle branched-chain amino acid oxidation contribute to impaired lipid metabolism

    Directory of Open Access Journals (Sweden)

    Carles Lerin

    2016-10-01

    Conclusions: Our data indicate that impaired muscle BCAA catabolism may contribute to the development of insulin resistance by perturbing both amino acid and fatty acid metabolism and suggest that targeting BCAA metabolism may hold promise for prevention or treatment of T2D.

  12. Atomistic stimulation of defective oxides

    CERN Document Server

    Minervini, L

    2000-01-01

    defect processes. The predominant intrinsic disorder reaction and the mechanism by which excess oxygen is accommodated are established. Furthermore, the most favourable migration mechanism and pathway for oxygen ions is predicted. Chapters 7 and 8 investigate pyrochlore oxides. These materials are candidates for solid oxide fuel cell components and as actinide host phases. Such applications require a detailed understanding of the defect processes. The defect energies, displayed as contour maps, are able to account for structure stability and, given an appropriate partial charge potential model, to accurately determine the oxygen positional parameter. In particular, the dependence of the positional parameter on intrinsic disorder is predicted. It is demonstrated, by radiation damage experiments, that these results are able to predict the radiation performance of pyrochlore oxides. Atomistic simulation calculations based on energy minimization techniques and classical pair potentials are used to study several i...

  13. Impurity-defect structure of anodic aluminum oxide produced by two-sided anodizing in tartaric acid

    Science.gov (United States)

    Chernyakova, K. V.; Vrublevsky, I. A.; Ivanovskaya, M. I.; Kotsikau, D. A.

    2012-03-01

    Porous aluminum oxide is prepared in a 0.4 M aqueous solution of tartaric acid by two-sided anodizing. Fourier Transform IR spectroscopy (FTIR) data reveal the presence, in the alumina, of unoxidized tartarate ions, as well as products of their partial (radical organic products and CO) and complete (CO2) oxidation. Carboxylate ions and elemental carbon contained in the anodic oxide impart a gray color to the films.

  14. Mutation analysis in mitochondrial fatty acid oxidation defects: Exemplified by acyl-CoA dehydrogenase deficiencies, with special focus on genotype-phenotype relationship

    DEFF Research Database (Denmark)

    Gregersen, N; Andresen, B S; Corydon, M J;

    2001-01-01

    Mutation analysis of metabolic disorders, such as the fatty acid oxidation defects, offers an additional, and often superior, tool for specific diagnosis compared to traditional enzymatic assays. With the advancement of the structural part of the Human Genome Project and the creation of mutation...... these practical uses emerges the possibility to study genotype-phenotype relationships and investigate the molecular pathogenesis resulting from specific mutations or groups of mutations. In the present review we summarize current knowledge regarding genotype-phenotype relationships in three disorders...... systems may help to assess the balance between genetic and environmental factors in the clinical expression of a given mutation. The realization that the effect of the monogene, such as disease-causing mutations in the VLCAD, MCAD, and SCAD genes, may be modified by variations in other genes presages...

  15. Fatty Acid Oxidation Disorders

    Science.gov (United States)

    ... acid oxidation disorders are tested for in newborn screening? The March of Dimes recommends that all babies ... in behavior Diarrhea, nausea (feeling sick to your stomach) and throwing up Drowsiness Fever Fussiness Little appetite ...

  16. Neonatal cardiomyopathies and metabolic crises due to oxidative phosphorylation defects.

    Science.gov (United States)

    Schiff, Manuel; Ogier de Baulny, Hélène; Lombès, Anne

    2011-08-01

    Neonatal cardiomyopathies due to mitochondrial oxidative phosphorylation (OXPHOS) defects are extremely severe conditions which can be either isolated or included in a multi-organ disease, with or without metabolic crises, of which profound lactic acidosis is the prominent feature. Cardiomyopathy is more often hypertrophic than dilated. Antenatal manifestations such as fetal cardiomyopathy, arrhythmia and/or hydrops have been reported. Pathophysiological mechanisms are complex, going beyond ATP deficiency of the high-energy-consuming neonatal myocardium. Birth is a key metabolic period when the myocardium switches ATP production from anaerobic glycolysis to mitochondrial fatty acid oxidation and OXPHOS. Heart-specificity of the defect may be related to the specific localization of the defect, to the high myocardium dependency on OXPHOS, and/or to interaction between the primary genetic alteration and other factors such as modifier genes. Therapeutic options are limited but standardized diagnostic procedures are mandatory to confirm the OXPHOS defect and to identify its causal mutation, allowing genetic counseling and potential prenatal diagnosis.

  17. Neural tube defect and folic acid.

    Science.gov (United States)

    Wani, M A

    2000-01-01

    Neural tube defect (NTD) is a group of congenital anomalies, which include anencephaly, encephalocele, iniencephaly, meningocele, myelomeningocele, myeloschisis, lipomeningocele, and rashischisis. Congenital malformations of the central nervous system constitute more than half of all congenital malformations with an incidence of 1-2/1000 births. The condition is thought to arise from multifactorial etiology with a distinct genetic predisposition. This paper discusses the pathogenesis of NTD and explores the use of folic acid for the prevention of this serious congenital malformation. Two studies, which have shown a significant protective effect of folic acid use on NTD prevention in high-risk mothers, are cited. In considering the effectiveness of folic acid supplementation on NTD prevention, obstetricians, pediatricians, neonatologists, and family doctors are called to initiate a collective effort to increase awareness among women in the childbearing age on the need of daily multivitamin intake with folic acid prior to pregnancy.

  18. Neural Tube Defects, Folic Acid and Methylation

    Directory of Open Access Journals (Sweden)

    Henk J. Blom

    2013-09-01

    Full Text Available Neural tube defects (NTDs are common complex congenital malformations resulting from failure of the neural tube closure during embryogenesis. It is established that folic acid supplementation decreases the prevalence of NTDs, which has led to national public health policies regarding folic acid. To date, animal studies have not provided sufficient information to establish the metabolic and/or genomic mechanism(s underlying human folic acid responsiveness in NTDs. However, several lines of evidence suggest that not only folates but also choline, B12 and methylation metabolisms are involved in NTDs. Decreased B12 vitamin and increased total choline or homocysteine in maternal blood have been shown to be associated with increased NTDs risk. Several polymorphisms of genes involved in these pathways have also been implicated in risk of development of NTDs. This raises the question whether supplementation with B12 vitamin, betaine or other methylation donors in addition to folic acid periconceptional supplementation will further reduce NTD risk. The objective of this article is to review the role of methylation metabolism in the onset of neural tube defects.

  19. Tissue-specific strategies of the very-long chain acyl-CoA dehydrogenase-deficient (VLCAD-/- mouse to compensate a defective fatty acid β-oxidation.

    Directory of Open Access Journals (Sweden)

    Sara Tucci

    Full Text Available Very long-chain acyl-CoA dehydrogenase (VLCAD-deficiency is the most common long-chain fatty acid oxidation disorder presenting with heterogeneous phenotypes. Similar to many patients with VLCADD, VLCAD-deficient mice (VLCAD(-/- remain asymptomatic over a long period of time. In order to identify the involved compensatory mechanisms, wild-type and VLCAD(-/- mice were fed one year either with a normal diet or with a diet in which medium-chain triglycerides (MCT replaced long-chain triglycerides, as approved intervention in VLCADD. The expression of the mitochondrial long-chain acyl-CoA dehydrogenase (LCAD and medium-chain acyl-CoA dehydrogenase (MCAD was quantified at mRNA and protein level in heart, liver and skeletal muscle. The oxidation capacity of the different tissues was measured by LC-MS/MS using acyl-CoA substrates with a chain length of 8 to 20 carbons. Moreover, in white skeletal muscle the role of glycolysis and concomitant muscle fibre adaptation was investigated. In one year old VLCAD(-/- mice MCAD and LCAD play an important role in order to compensate deficiency of VLCAD especially in the heart and in the liver. However, the white gastrocnemius muscle develops alternative compensatory mechanism based on a different substrate selection and increased glucose oxidation. Finally, the application of an MCT diet over one year has no effects on LCAD or MCAD expression. MCT results in the VLCAD(-/- mice only in a very modest improvement of medium-chain acyl-CoA oxidation capacity restricted to cardiac tissue. In conclusion, VLCAD(-/- mice develop tissue-specific strategies to compensate deficiency of VLCAD either by induction of other mitochondrial acyl-CoA dehydrogenases or by enhancement of glucose oxidation. In the muscle, there is evidence of a muscle fibre type adaptation with a predominance of glycolytic muscle fibres. Dietary modification as represented by an MCT-diet does not improve these strategies long-term.

  20. Dopants and defects in conductive oxide spinels

    Science.gov (United States)

    Zakutayev, Andriy; Perkins, John; Parilla, Phillip; Paudel, Tula; Lany, Staphan; Ginely, David; Zunger, Alex

    2011-03-01

    We will discuss the effects of extrinsic and intrinsic imperfections (dopants and defects) in a group of conductive oxide materials related to Co3O4. Co3O4 is a spinel with Co2+ and Co3+ on tetrahedral and octahedral sites, respectively. Doping of Co3O4 with Zn and Ni represent two limiting cases: Zn2+ ions have a preference to occupy tetrahedral (Co2+) sites and are predicted to be unable to dope effectively; Ni2+ ions have a preference to occupy octahedral (Co3+) sites, so these atoms are expected to be efficient dopants. We found that substitution of Co3O4 spinel with up to 33 percent of Zn and Ni results in formation of ZnCo2O4 normal spinel and NiCo2O4 inverse spinel, and causes 100-fold and 1000-fold increases in conductivity, respectively, matching the predicted trend. Increase in Zn and Ni concentraion up to 40 percent cause phase separation of ZnO and NiO and leveling out of the conductivity. The conductivity decreases sharply above 50-60 percent Zn and Ni substitution level. Small differences with the theoretical predictions may be explained by non-equilibrium character of the thin film deposition process. This work was supported by the ``Center for Inverse Design'' EFRC of the Department of Energy.

  1. Delay Testing Viability of Gate Oxide Short Defects

    Institute of Scientific and Technical Information of China (English)

    J. M. Gallière; M. Renovell; F.Aza(i)s; Y. Bertrand

    2005-01-01

    Gate Oxide Short (GOS) defects are becoming predominant as technology is scaling down. Boolean and IDDQ testing of this defect has been widely studied but there is no paper dedicated to delay testing of this defect. So, this paper studies the delay behavior of Gate Oxide Short faults due to pinhole in the gate oxide. The objective of this paper is to give a detailed analysis of the behavior of the GOS defect taking into account the random parameter of the defect such as the GOS resistance and the GOS location. Because an accurate analysis is desired, the bi-dimensional array will be used.Because a complete analysis is desired, we derive the dynamic characteristic of the GOS as a function of the GOS resistance and location. It is demonstrated that i) GOS has a significant impact on gate delay, ii) GOS located close to the source of the transistor and with small resistance has very high impact.

  2. Defect centers in chemical-mechanical polished MOS oxides

    Energy Technology Data Exchange (ETDEWEB)

    Shaneyfelt, M.R.; Warren, W.L.; Hetherington, D.L.; Timon, R.P.; Resnick, P.J.; Winokur, P.S.

    1994-12-31

    Defect centers generated in vacuum-ultraviolet irradiated chemical-mechanical polished oxides have been characterized using electron paramagnetic resonance and C-V analysis. Both oxide trap E{sub {gamma}} and interface trap P{sub b0} centers were detected in unpolished and polished oxides. In addition, another interface defect center known as the P{sub b1} center was only identified in the polished oxides, suggesting that the polishing process altered the SiO{sub 2}/Si interface.

  3. Defects and oxidation resilience in InSe

    Science.gov (United States)

    Xiao, K. J.; Carvalho, A.; Castro Neto, A. H.

    2017-08-01

    We use density functional theory to study intrinsic defects and oxygen related defects in indium selenide. We find that InSe is prone to oxidation, but however not reacting with oxygen as strongly as phosphorene. The dominant intrinsic defects in In-rich material are the In interstitial, a shallow donor, and the Se vacancy, which introduces deep traps. The latter can be passivated by oxygen, which is isoelectronic with Se. The dominant intrinsic defects in Se-rich material have comparatively higher formation energies.

  4. Cation Defects and Conductivity in Transparent Oxides

    Energy Technology Data Exchange (ETDEWEB)

    Exarhos, Gregory J.; Windisch, Charles F.; Ferris, Kim F.; Owings, Robert R.

    2007-10-24

    High quality doped zinc oxide and mixed transition metal spinel oxide films have been deposited by means of sputter deposition from metal and metal oxide targets, and by spin casting from aqueous or alcoholic precursor solutions. Deposition conditions and post-deposition processing are found to alter cation oxidation states and their distributions in both oxide materials resulting in marked changes to both optical transmission and electrical response. For ZnO, partial reduction of the neat or doped material by hydrogen treatment of the heated film or by electrochemical processing renders the oxide n-type conducting. Continued reduction was found to diminish conductivity. In contrast, oxidation of the infrared transparent p-type spinel conductors typified by NiCo2O4 was found to increase conductivity. The disparate behavior of these two materials is caused in part by the sign of the charge carrier and by the existence of two different charge transport mechanisms that are identified as free carrier conduction and polaron hopping. While much work has been reported concerning structure/property relationships in the free carrier conducting oxides, there is a significantly smaller body of information on transparent polaron conductors. In this paper, we identify key parameters that promote conductivity in mixed metal spinel oxides and compare their behavior with that of the free carrier TCO’s.

  5. Evaluation of defects in cuprous oxide through exciton luminescence imaging

    Energy Technology Data Exchange (ETDEWEB)

    Frazer, Laszlo, E-mail: jl@laszlofrazer.com [Department of Physics, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Lenferink, Erik J. [Department of Physics, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Chang, Kelvin B. [Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Poeppelmeier, Kenneth R. [Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Stern, Nathaniel P. [Department of Physics, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Ketterson, John B. [Department of Physics, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Department of Electrical Engineering and Computer Science, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States)

    2015-03-15

    The various decay mechanisms of excitons in cuprous oxide (Cu{sub 2}O) are highly sensitive to defects which can relax selection rules. Here we report cryogenic hyperspectral imaging of exciton luminescence from cuprous oxide crystals grown via the floating zone method showing that the samples have few defects. Some locations, however, show strain splitting of the 1s orthoexciton triplet polariton luminescence. Strain is reduced by annealing. In addition, annealing causes annihilation of oxygen and copper vacancies, which leads to a negative correlation between luminescence of unlike vacancies. - Highlights: • We use luminescence to observe defects in high quality cuprous oxide crystals. • Strain is reduced by annealing. • Annealing causes annihilation of oxygen and copper vacancies.

  6. New Guidelines Reaffirm Prenatal Folic Acid to Curb Birth Defects

    Science.gov (United States)

    ... https://medlineplus.gov/news/fullstory_162970.html New Guidelines Reaffirm Prenatal Folic Acid to Curb Birth Defects ... HealthDay News) -- In a recommendation that reaffirms previous guidelines, the U.S. Preventive Services Task Force said that ...

  7. The primary prevention of birth defects: Multivitamins or folic acid?

    Directory of Open Access Journals (Sweden)

    2004-03-01

    Full Text Available Periconceptional use of folic acid alone or in multivitamin supplements is effective for the primary prevention of neural-tube defects. The Hungarian randomized and two-cohort controlled trials showed that periconceptional multivitamin supplementation can reduce the occurrence of some other structural birth defects, i.e. congenital abnormalities. These findings were supported by many, but not all observational studies. Recently there have been two main debated questions. The first one is whether the use of folic acid alone or folic acid-containing multivitamins is better. The second one is connected with the dilemma of whether high dose of folic acid (e.g. 5 mg might be better than a daily multivitamin with 0.4 – 0.8 mg of folic acid. Comparison of the pooled data of two Hungarian trials using a multivitamin containing 0.8 mg folic acid and the data of the Hungarian Case-Control Surveillance of Congenital Abnormalities using high dose of folic acid seemed to be appropriate to answer these questions. Multivitamins containing 0.4 – 0.8 mg of folic acid were more effective for the reduction of neural-tube defects than high dose of folic acid. Both multivitamins and folic acid can prevent some part of congenital cardiovascular malformations. Only multivitamins were able to reduce the prevalence at birth of obstructive defects of urinary tract, limb deficiencies and congenital pyloric stenosis. However, folic acid was effective in preventing some part of rectal/anal stenosis/atresia, and high dose of folic acid had effect in preventing some orofacial clefts. The findings are consistent that periconceptional multivitamin and folic acid supplementation reduce the overall occurrence of congenital abnormalities in addition to the demonstrated effect on neural-tube defects.

  8. Differential diagnosis in patients with suspected bile acid synthesis defects

    Institute of Scientific and Technical Information of China (English)

    Dorothea Haas; Hongying Gan-Schreier; Claus-Dieter Langhans; Tilman Rohrer; Guido Engelmann; Maura Heverin; David W Russell

    2012-01-01

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

  9. Effects of oxidation on the defect of reduced graphene oxides in graphene preparation.

    Science.gov (United States)

    Hu, Yang; Song, Shaoxian; Lopez-Valdivieso, Alejandro

    2015-07-15

    The relationship between the defects of reduced graphene oxide (RGO) and the oxidation degree of graphite in the preparation of graphene with chemical conversion method has been studied in this work. This study was performed on an artificial graphite through the measurements of X ray diffraction, Raman spectroscopy and particle size analysis. The experimental results have shown that there indeed was a close relationship between the defects and the oxidation degree, which appeared in the form of S-type curve. Also, it was found that a low KMnO4 addition would lead to a partial oxidation of graphite, leaving defects mainly on the edges of RGO; with a high KMnO4 addition, the defects on RGO mostly appeared on the surfaces.

  10. Implications of impaired ketogenesis in fatty acid oxidation disorders.

    Science.gov (United States)

    Olpin, Simon Edward

    2004-03-01

    Long-chain fatty acids are important sources of respiratory fuel for many tissues and during fasting the rate of hepatic production of ketone bodies is markedly increased. Many extra hepatic tissues utilize ketone bodies in the fasted state with the advantage that glucose is "spared" for more vital tissues like the brain. This glucose sparing effect of ketones is especially important in infants where there is a high proportional glucose utilization in cerebral tissue. The first reported inherited defect affecting fatty acid oxidation was described in 1973 and to date about 15 separate disorders have been described. Although individually rare, cumulatively fatty acid oxidation defects are relatively common, have major consequences for affected individuals and their families, and carry significant health care implications. The major biochemical consequence of fatty acid oxidation defects is an inability of extra hepatic tissues to utilize fatty acids as an energy source with absent or limited hepatic capacity to generate ketones. Clinically patients usually present in infancy with acute life-threatening hypoketotic hypoglycaemia, liver disease, hyperammonaemia and cerebral oedema, with or without cardiac involvement, usually following a period of catabolic stress. Chronically there may be muscle involvement with hypotonia or exercise intolerance with or without cardiomyopathy. Treatment is generally by the avoidance of fasting, frequent carbohydrate rich feeds and for long-chain defects, the replacement of long-chain dietary fats with medium-chain formulae. Novel approaches to treatment include the use of d,l-3-hydoxybutyrate or heptanoate as an alternative energy source.

  11. [Folic acid: Primary prevention of neural tube defects. Literature Review].

    Science.gov (United States)

    Llamas Centeno, M J; Miguélez Lago, C

    2016-03-01

    Neural tube defects (NTD) are the most common congenital malformations of the nervous system, they have a multifactorial etiology, are caused by exposure to chemical, physical or biological toxic agents, factors deficiency, diabetes, obesity, hyperthermia, genetic alterations and unknown causes. Some of these factors are associated with malnutrition by interfering with the folic acid metabolic pathway, the vitamin responsible for neural tube closure. Its deficit produce anomalies that can cause abortions, stillbirths or newborn serious injuries that cause disability, impaired quality of life and require expensive treatments to try to alleviate in some way the alterations produced in the embryo. Folic acid deficiency is considered the ultimate cause of the production of neural tube defects, it is clear the reduction in the incidence of Espina Bifida after administration of folic acid before conception, this leads us to want to further study the action of folic acid and its application in the primary prevention of neural tube defects. More than 40 countries have made the fortification of flour with folate, achieving encouraging data of decrease in the prevalence of neural tube defects. This paper attempts to make a literature review, which clarify the current situation and future of the prevention of neural tube defects.

  12. Defects and defect generation in oxide layer of ion implanted silicon-silicon dioxide structures

    CERN Document Server

    Baraban, A P

    2002-01-01

    One studies mechanism of generation of defects in Si-SiO sub 2 structure oxide layer as a result of implantation of argon ions with 130 keV energy and 10 sup 1 sup 3 - 3.2 x 10 sup 1 sup 7 cm sup - sup 2 doses. Si-SiO sub 2 structures are produced by thermal oxidation of silicon under 950 deg C temperature. Investigations were based on electroluminescence technique and on measuring of high-frequency volt-farad characteristics. Increase of implantation dose was determined to result in spreading of luminosity centres and in its maximum shifting closer to boundary with silicon. Ion implantation was shown, as well, to result in increase of density of surface states at Si-SiO sub 2 interface. One proposed model of defect generation resulting from Ar ion implantation into Si-SiO sub 2

  13. The inborn errors of mitochondrial fatty acid oxidation.

    Science.gov (United States)

    Vianey-Liaud, C; Divry, P; Gregersen, N; Mathieu, M

    1987-01-01

    To date, seven inborn errors of mitochondrial fatty acid oxidation have been identified. A total of about 100 patients in the world have been reported. Clinically the beta-oxidation defects are more often characterized by episodic hypoglycaemia leading to a coma mimicking Reye's syndrome. The hypoglycaemia is non-ketotic since the synthesis of ketone bodies is deficient. Periods of decompensation occur when carbohydrate supply is poor, e.g. prolonged fasting, vomiting, or increased caloric requirements, as and when lipid stores are used. Defects in beta-oxidation have also been reported to be one cause of sudden infant death syndrome. The diagnosis of these inborn errors is by biochemical investigation since where symptoms suggest such a defect, the precise aetiology cannot be assessed. The biochemical diagnosis is based firstly on identification of abnormal plasma and of urinary metabolites during acute attacks. Derivatives of the omega-oxidation and omega-1-oxidation of medium chain fatty acids have been identified, as well as acylglycine and acylcarnitine conjugates. These metabolites are nearly always absent when patients are in good clinical condition. Secondly, the diagnosis must be based on the identification of the enzymatic defects: this involves global assays which allow a localization of the 'level' of the defect (i.e. the oxidation of long, medium or short chain fatty acids) and specific measurement of enzyme activities (acyl-CoA dehydrogenases and electron carriers: ETF and ETF-DH). The diagnosis of these disorders is of prime importance because of the severity of the clinical symptoms. These can be prevented, in some cases, by an appropriate diet (a high carbohydrate, low fat diet, sometimes supplemented with L-carnitine). In other cases, genetic counselling can be offered.

  14. Towards precise defect control in layered oxide structures by using oxide molecular beam epitaxy

    Directory of Open Access Journals (Sweden)

    Federico Baiutti

    2014-05-01

    Full Text Available In this paper we present the atomic-layer-by-layer oxide molecular beam epitaxy (ALL-oxide MBE which has been recently installed in the Max-Planck Institute for Solid State Research and we report on its present status, providing some examples that demonstrate its successful application in the synthesis of different layered oxides, with particular reference to superconducting La2CuO4 and insulator-to-metal La2−xSrxNiO4. We briefly review the ALL-oxide MBE technique and its unique capabilities in the deposition of atomically smooth single-crystal thin films of various complex oxides, artificial compounds and heterostructures, introducing our goal of pursuing a deep investigation of such systems with particular emphasis on structural defects, with the aim of tailoring their functional properties by precise defects control.

  15. Towards precise defect control in layered oxide structures by using oxide molecular beam epitaxy.

    Science.gov (United States)

    Baiutti, Federico; Christiani, Georg; Logvenov, Gennady

    2014-01-01

    In this paper we present the atomic-layer-by-layer oxide molecular beam epitaxy (ALL-oxide MBE) which has been recently installed in the Max-Planck Institute for Solid State Research and we report on its present status, providing some examples that demonstrate its successful application in the synthesis of different layered oxides, with particular reference to superconducting La2CuO4 and insulator-to-metal La2- x Sr x NiO4. We briefly review the ALL-oxide MBE technique and its unique capabilities in the deposition of atomically smooth single-crystal thin films of various complex oxides, artificial compounds and heterostructures, introducing our goal of pursuing a deep investigation of such systems with particular emphasis on structural defects, with the aim of tailoring their functional properties by precise defects control.

  16. Neuropsychological Outcomes in Fatty Acid Oxidation Disorders: 85 Cases Detected by Newborn Screening

    Science.gov (United States)

    Waisbren, Susan E.; Landau, Yuval; Wilson, Jenna; Vockley, Jerry

    2013-01-01

    Mitochondrial fatty acid oxidation disorders include conditions in which the transport of activated acyl-Coenzyme A (CoA) into the mitochondria or utilization of these substrates is disrupted or blocked. This results in a deficit in the conversion of fat into energy. Most patients with fatty acid oxidation defects are now identified through…

  17. Folic Acid and Birth Defects: A Case Study (Iran

    Directory of Open Access Journals (Sweden)

    Mohammad Bager Hosseini

    2011-01-01

    Full Text Available The aim of this study was to evaluate the impact of folic acid use in pregnancy for the reduction of neural tube defects (NTDs in the northwest region of Iran. We studied 243 women with pregnancies complicated by some forms of birth defect(s. These patients were identified by medical diagnostic tests as having a fetus with some types of congenital anomalies. The prevalence of NTDs among pregnant women who were referred for therapeutic termination of pregnancy was 24.7 percent. Consumption of folic acid prevented NTDs by 79 percent (Odds Ratio = 0.21, CI 95%: 0.12–0.40 and 94 percent (Odds Ratio = 0.06, CI 95%: 0.03–0.15 compared to pregnancies complicated by other anomalies and normal pregnancies, respectively. Hydrops fetalis, hydrocephaly, Down syndrome, and limb anomalies did not have any significant association with the folic acid use. Along with the advice for the consumption of folic acid for pregnant women, they should be offered prenatal screening or diagnostic tests to identify fetal abnormalities for possible termination of pregnancy.

  18. Defective acid hydrolase secretion in RUNX1 haplodeficiency: Evidence for a global platelet secretory defect.

    Science.gov (United States)

    Rao, A K; Poncz, M

    2017-06-29

    RUNX1 haplodeficiency is associated with thrombocytopenia, platelet dysfunction and a predisposition to acute leukaemia. Platelets possess three distinct types of granules and secretory processes involving dense granules (DG), α-granules and vesicles or lysosomes containing acid hydrolases (AH). Dense granules and granule deficiencies have been reported in patients with RUNX1 mutations. Little is known regarding the secretion from AH-containing vesicles. We studied two related patients with a RUNX1 mutation, easy bruising, and mild thrombocytopenia. Platelet aggregation and (14) C serotonin in platelet-rich plasma (PRP) were impaired in response to ADP, epinephrine, collagen and arachidonic acid. Contents of DG (ATP, ADP), α-granules (β-thromboglobulin) and AH-containing vesicles (β-glucuronidase, β-hexosaminidase, α-mannosidase) were normal or minimally decreased. Dense granules secretion on stimulation of gel-filtered platelets with thrombin and divalent ionophore A23187 (4-12 μmol L(-1) ) were diminished. β-thromboglobulin and AH secretion was impaired in response to thrombin or A23187. We studied thromboxane-related pathways. The incorporation of (14) C -arachidonic acid into phospholipids and subsequent arachidonic acid release on thrombin activation was normal. Platelet thromboxane A2 production in whole blood serum and on thrombin stimulation of PRP was normal, suggesting that the defective secretion was not due to impaired thromboxane production. These studies provide the first evidence in patients with a RUNX1 mutation for a defect in AH (lysosomal) secretion, and for a global defect in secretion involving all three types of platelet granules that is unrelated to a granule content deficiency. They highlight the pleiotropic effects and multiple platelet defects associated with RUNX1 mutations. © 2017 John Wiley & Sons Ltd.

  19. Defect Engineering and Interface Phenomena in Tin Oxide

    KAUST Repository

    Albar, Arwa

    2017-04-05

    The advance in transparent electronics requires high-performance transparent conducting oxide materials. The microscopic properties of these materials are sensitive to the presence of defects and interfaces and thus fundamental understanding is required for materials engineering. In this thesis, first principles density functional theory is used to investigate the possibility of tuning the structural, electronic and magnetic properties of tin oxide by means of defects and interfaces. Our aim is to reveal unique properties and the parameters to control them as well as to explain the origin of unique phenomena in oxide materials. The stability of native defect in tin monoxide (SnO) under strain is investigated using formation energy calculations. We find that the conductivity (which is controlled by native defects) can be switched from p-type to either n-type or undoped semiconducting by means of applied pressure. We then target inducing magnetism in SnO by 3d transition metal doping. We propose that V doping is efficient to realize spin polarization at high temperature. We discuss different tin oxide interfaces. Metallic states are found to form at the SnO/SnO2 interface with electronic properties that depend on the interface terminations. The origin of these states is explained in terms of charge transfer caused by chemical bonding and band alignment. For the SnO/SnO2 heterostructure, we observe the formation of a two dimensional hole gas at the interface, which is surprising as it cannot be explained by the standard polar catastrophe model. Thus, we propose a charge density discontinuity model to explain our results. The model can be generalized to other polar-polar interfaces. Motivated by technological applications, the electronic and structural properties of the MgO (100)/SnO2 (110) interface are investigated. Depending on the interface termination, we observe the formation of a two dimensional electron gas or spin polarized hole gas. Aiming to identify further

  20. Refsum disease, peroxisomes and phytanic acid oxidation: a review.

    Science.gov (United States)

    Wanders, R J; Jansen, G A; Skjeldal, O H

    2001-11-01

    Refsum disease was first recognized as a distinct disease entity by Sigvald Refsum in the 1940s. The discovery of markedly elevated levels of the branched-chain fatty acid phytanic acid in certain patients marked Refsum disease as a disorder of lipid metabolism. Although it was immediately recognized that the accumulation of phytanic acid is due to its deficient breakdown in Refsum disease patients, the true enzymatic defect remained mysterious until recently. A major breakthrough in this respect was the resolution of the mechanism of phytanic acid alpha-oxidation in humans. In this review we describe the many aspects of Refsum disease from the clinical signs and symptoms to the enzyme and molecular defect plus the recent identification of genetic heterogeneity in Refsum disease.

  1. Radiation induced defects and thermoluminescence mechanism in aluminum oxide

    Energy Technology Data Exchange (ETDEWEB)

    Atobe, K.; Kobayashi, T.; Awata, T. [Naruto Univ. of Education, Tokushima (Japan); Okada, M. [Kyoto Univ., Kumatori, Osaka (Japan). Research Reactor Inst; Nakagawa, M. [Kagawa Univ., Faculty of Education, Takamatsu, Kagawa (Japan)

    2001-01-01

    The thermoluminescence of the irradiated aluminum oxides were measured to study the radiation induced defects and their behaviors. Neutron and {gamma}-ray irradiation were performed for a shingle crystal of the high purity aluminum oxide. The thermoluminescence glow curve and its activation energy were measured. The spectroscopy measurement on the thermoluminescence and the absorption are also carried out. The observed 430 and 340 nm peaks are discussed relating to the F{sup +} and F centers, respectively. Activation state of the F center transits to 3P state through 1P state by emitting phonons. Trapped electron on 3P state emits phonon of 2.9 eV (430 nm) during transition to the ground state. The above reaction can be written by the equation. F{sup +} + e {yields} (F){sup *} {yields} F + h{nu}(2.9 eV, 470 nm). (Katsuta, H.)

  2. Thermal oxidation of Ge-implanted Si: Role of defects

    Science.gov (United States)

    Dedyulin, S. N.; Goncharova, L. V.

    2012-02-01

    Thermal oxidation of Ge-implanted Si (SiGe) was carried out in dry O at 1073, 1173, and 1273 K for various times. Rutherford backscattering spectrometry in random and channeling geometry was used to characterize the SiO thickness and composition of the Si (dry oxidation) [3,4,8,9,13-17] or by bubbling N/O through HO (wet oxidation) [5-7,9-12,18]. In these studies SiGe thin films were obtained by different growth techniques such as chemical vapor deposition (CVD) [4-6,19,12], molecular beam epitaxy (MBE) [7,8,14,19,21-23], physical evaporation [3,18] as well as Ge ion implantation in Si [9-11,13,15-17]. Despite the great differences in the preparation of SiGe samples and oxidation procedures, the main features of SiGe thermal oxidation may be summarized by the following: Pure SiO was formed during oxidation: Ge atoms that were rejected from the growing silicon oxide piled up at the interface. This was observed in all cases, unless the temperature was low enough (⩽973 K)[24], or the oxidation pressure was high [6,19], or the Ge concentration, x, in the alloy satisfied x⩾0.5[7,8], or the oxidation time was very short [22,23]. All these conditions prevent Ge diffusion away from the reacting interface. The oxidation rate of SiGe in a wet atmosphere was enhanced in comparison to pure Si [4,5,9-12,18,25], while there was no enhancement in the dry O[9,16,22,25] (unless the sample was first pre-enriched with Ge to form approximately one monolayer of Ge at the interface [9]). Oxidation rate enhancement occurs during an initial linear regime of oxide growth [10]. SiGe oxidation rate enhancement has been explained by: (i) the weaker Si-Ge bond [11], (ii) Ge catalytic role for oxidation reaction [12], and (iii) changes in defect generation at the reacting interface [12]. It was shown for Ge ion implanted samples that the Deal and Grove model (DG model) for Si oxidation can still be applied with the linear B/ A constant modified to take into account enhanced oxidation

  3. Controlled Defects of Zinc Oxide Nanorods for Efficient Visible Light Photocatalytic Degradation of Phenol

    Directory of Open Access Journals (Sweden)

    Jamal Al-Sabahi

    2016-03-01

    Full Text Available Environmental pollution from human and industrial activities has received much attention as it adversely affects human health and bio-diversity. In this work we report efficient visible light photocatalytic degradation of phenol using supported zinc oxide (ZnO nanorods and explore the role of surface defects in ZnO on the visible light photocatalytic activity. ZnO nanorods were synthesized on glass substrates using a microwave-assisted hydrothermal process, while the surface defect states were controlled by annealing the nanorods at various temperatures and were characterized by photoluminescence and X-ray photoelectron spectroscopy. High performance liquid chromatography (HPLC was used for the evaluation of phenol photocatalytic degradation. ZnO nanorods with high surface defects exhibited maximum visible light photocatalytic activity, showing 50% degradation of 10 ppm phenol aqueous solution within 2.5 h, with a degradation rate almost four times higher than that of nanorods with lower surface defects. The mineralization process of phenol during degradation was also investigated, and it showed the evolution of different photocatalytic byproducts, such as benzoquinone, catechol, resorcinol and carboxylic acids, at different stages. The results from this study suggest that the presence of surface defects in ZnO nanorods is crucial for its efficient visible light photocatalytic activity, which is otherwise only active in the ultraviolet region.

  4. Aspirin increases mitochondrial fatty acid oxidation.

    Science.gov (United States)

    Uppala, Radha; Dudiak, Brianne; Beck, Megan E; Bharathi, Sivakama S; Zhang, Yuxun; Stolz, Donna B; Goetzman, Eric S

    2017-01-08

    The metabolic effects of salicylates are poorly understood. This study investigated the effects of aspirin on fatty acid oxidation. Aspirin increased mitochondrial long-chain fatty acid oxidation, but inhibited peroxisomal fatty acid oxidation, in two different cell lines. Aspirin increased mitochondrial protein acetylation and was found to be a stronger acetylating agent in vitro than acetyl-CoA. However, aspirin-induced acetylation did not alter the activity of fatty acid oxidation proteins, and knocking out the mitochondrial deacetylase SIRT3 did not affect the induction of long-chain fatty acid oxidation by aspirin. Aspirin did not change oxidation of medium-chain fatty acids, which can freely traverse the mitochondrial membrane. Together, these data indicate that aspirin does not directly alter mitochondrial matrix fatty acid oxidation enzymes, but most likely exerts its effects at the level of long-chain fatty acid transport into mitochondria. The drive on mitochondrial fatty acid oxidation may be a compensatory response to altered mitochondrial morphology and inhibited electron transport chain function, both of which were observed after 24 h incubation of cells with aspirin. These studies provide insight into the pathophysiology of Reye Syndrome, which is known to be triggered by aspirin ingestion in patients with fatty acid oxidation disorders. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. Folic acid supplementation during pregnancy protects against lipopolysaccharide-induced neural tube defects in mice.

    Science.gov (United States)

    Zhao, Mei; Chen, Yuan-Hua; Chen, Xue; Dong, Xu-Ting; Zhou, Jun; Wang, Hua; Wu, Shu-Xian; Zhang, Cheng; Xu, De-Xiang

    2014-01-13

    Folic acid is a water-soluble B-complex vitamin. Increasing evidence demonstrates that physiological supply of folic acid during pregnancy prevents folic acid deficiency-related neural tube defects (NTDs). Previous studies showed that maternal lipopolysaccharide (LPS) exposure caused NTDs in rodents. The aim of this study was to investigate the effects of high-dose folic acid supplementation during pregnancy on LPS-induced NTDs. Pregnant mice were intraperitoneally injected with LPS (20 μg/kg/d) from gestational day (GD) 8 to GD12. As expected, a five-day LPS injection resulted in 19.96% of fetuses with NTDs. Interestingly, supplementation with folic acid (3mg/kg/d) during pregnancy significantly alleviated LPS-induced NTDs. Additionally, folic acid significantly attenuated LPS-induced fetal growth restriction and skeletal malformations. Additional experiment showed that folic acid attenuated LPS-induced glutathione (GSH) depletion in maternal liver and placentas. Moreover, folic acid significantly attenuated LPS-induced expression of placental MyD88. Additionally, folic acid inhibited LPS-induced c-Jun NH2-terminal kinase (JNK) phosphorylation and nuclear factor kappa B (NF-κB) activation in placentas. Correspondingly, folic acid significantly attenuated LPS-induced tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6 in placentas, maternal serum and amniotic fluid. In conclusion, supplementation with high-dose folic acid during pregnancy protects against LPS-induced NTDs through its anti-inflammatory and anti-oxidative effects.

  6. Mitochondrial accumulation under oxidative stress is due to defects in autophagy.

    Science.gov (United States)

    Luo, Cheng; Li, Yan; Wang, Hui; Feng, Zhihui; Li, Yuan; Long, Jiangang; Liu, Jiankang

    2013-01-01

    Mitochondrial dynamics maintains normal mitochondrial function by degrading damaged mitochondria and generating newborn mitochondria. The accumulation of damaged mitochondria influences the intracellular environment by promoting mitochondrial dysfunction, and thus initiating a vicious cycle. Oxidative stress induces mitochondrial malfunction, which is involved in many cardiovascular diseases. However, the mechanism of mitochondrial accumulation in cardiac myoblasts remains unclear. We observed mitochondrial dysfunction and an increase in mitochondrial mass under the oxidative conditions produced by tert-butyl hydroperoxide (tBHP) in cardiac myoblast H9c2 cells. However, in contrast to the increase in mitochondrial mass, mitochondrial DNA (mtDNA) decreased, suggesting that enhanced mitochondrial biogenesis may be not the primary cause of the mitochondrial accumulation. Therefore, we investigated changes in a number of proteins involved in autophagy. Beclin1, Atg12-Atg5 conjugate, Atg7 contents decreased but LC3-II accumulated in tBHP-treated H9c2 cells. Moreover, the capacity for acid hydrolysis decreased in H9c2 cells. We also demonstrated a decrease in DJ-1 protein under the oxidative conditions that deregulate mitochondrial dynamics. These results reveal that autophagy became defective under oxidative stress. We therefore suggest that defects in autophagy mediate mitochondrial accumulation under these conditions.

  7. Defective intestinal amino acid absorption in Ace2 null mice.

    Science.gov (United States)

    Singer, Dustin; Camargo, Simone M R; Ramadan, Tamara; Schäfer, Matthias; Mariotta, Luca; Herzog, Brigitte; Huggel, Katja; Wolfer, David; Werner, Sabine; Penninger, Josef M; Verrey, François

    2012-09-15

    Mutations in the main intestinal and kidney luminal neutral amino acid transporter B(0)AT1 (Slc6a19) lead to Hartnup disorder, a condition that is characterized by neutral aminoaciduria and in some cases pellagra-like symptoms. These latter symptoms caused by low-niacin are thought to result from defective intestinal absorption of its precursor L-tryptophan. Since Ace2 is necessary for intestinal B(0)AT1 expression, we tested the impact of intestinal B(0)AT1 absence in ace2 null mice. Their weight gain following weaning was decreased, and Na(+)-dependent uptake of B(0)AT1 substrates measured in everted intestinal rings was defective. Additionally, high-affinity Na(+)-dependent transport of L-proline, presumably via SIT1 (Slc6a20), was absent, whereas glucose uptake via SGLT1 (Slc5a1) was not affected. Measurements of small intestine luminal amino acid content following gavage showed that more L-tryptophan than other B(0)AT1 substrates reach the ileum in wild-type mice, which is in line with its known lower apparent affinity. In ace2 null mice, the absorption defect was confirmed by a severalfold increase of L-tryptophan and of other neutral amino acids reaching the ileum lumen. Furthermore, plasma and muscle levels of glycine and L-tryptophan were significantly decreased in ace2 null mice, with other neutral amino acids displaying a similar trend. A low-protein/low-niacin diet challenge led to differential changes in plasma amino acid levels in both wild-type and ace2 null mice, but only in ace2 null mice to a stop in weight gain. Despite the combination of low-niacin with a low-protein diet, plasma niacin concentrations remained normal in ace2 null mice and no pellagra symptoms, such as photosensitive skin rash or ataxia, were observed. In summary, mice lacking Ace2-dependent intestinal amino acid transport display no total niacin deficiency nor clear pellagra symptoms, even under a low-protein and low-niacin diet, despite gross amino acid homeostasis alterations.

  8. Hybrid functional studies of defects and hole polarons in oxides

    Science.gov (United States)

    Varley, Joel

    Transparent conducting oxides (TCOs) are ubiquitous, appearing in windows, flat-panel displays, solar cells, solid-state lighting, and transistors that all exploit TCOs' combination of high electrical conductivity and optical transparency. Thanks to this large and growing list of applications, there has been a surge of interest in the science of these materials, focusing on the fundamental properties and doping opportunities in traditional TCOs as well as the exploration of promising new candidate materials. Hybrid density functional theory has proven instrumental in elucidating the physics of TCOs. One example is the study of dopants and defects that determine the conductivity. Accurate formation energies and charge-state transition levels can now be obtained thanks to the accurate electronic structure provided by a hybrid functional. This allows us to address the origins of unintentional conductivity: for SnO2, In2O3, and Ga2O3, we demonstrate that this is not due to native defects such as oxygen vacancies, but must be attributed to unintentional incorporation of impurities. We can also provide guidelines for achieving higher doping levels, suggesting several impurities as candidate donors with high solubility. Limitations on doping due to the formation or incorporation of compensating centers are addressed as well. Hybrid functional calculations also overcome the shortcomings associated with traditional local or semi-local functionals, which do not properly describe charge localization. Hybrid functionals accurately describe polaron formation, i.e., the self-trapping of holes when p - type doping of the oxide materials is attempted. Consequences of polaron formation for optical characterization of the material will be discussed. This work was performed in collaboration with Anderson Janotti and Chris G. Van de Walle, and was in part under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  9. Nickel inhibits mitochondrial fatty acid oxidation.

    Science.gov (United States)

    Uppala, Radha; McKinney, Richard W; Brant, Kelly A; Fabisiak, James P; Goetzman, Eric S

    2015-08-07

    Nickel exposure is associated with changes in cellular energy metabolism which may contribute to its carcinogenic properties. Here, we demonstrate that nickel strongly represses mitochondrial fatty acid oxidation-the pathway by which fatty acids are catabolized for energy-in both primary human lung fibroblasts and mouse embryonic fibroblasts. At the concentrations used, nickel suppresses fatty acid oxidation without globally suppressing mitochondrial function as evidenced by increased glucose oxidation to CO2. Pre-treatment with l-carnitine, previously shown to prevent nickel-induced mitochondrial dysfunction in neuroblastoma cells, did not prevent the inhibition of fatty acid oxidation. The effect of nickel on fatty acid oxidation occurred only with prolonged exposure (>5 h), suggesting that direct inhibition of the active sites of metabolic enzymes is not the mechanism of action. Nickel is a known hypoxia-mimetic that activates hypoxia inducible factor-1α (HIF1α). Nickel-induced inhibition of fatty acid oxidation was blunted in HIF1α knockout fibroblasts, implicating HIF1α as one contributor to the mechanism. Additionally, nickel down-regulated the protein levels of the key fatty acid oxidation enzyme very long-chain acyl-CoA dehydrogenase (VLCAD) in a dose-dependent fashion. In conclusion, inhibition of fatty acid oxidation by nickel, concurrent with increased glucose metabolism, represents a form of metabolic reprogramming that may contribute to nickel-induced carcinogenesis.

  10. Ursodeoxycholic acid improves gastrointestinal motility defects in gallstone patients

    Institute of Scientific and Technical Information of China (English)

    A Colecchia; G Mazzella; L Sandri; F Azzaroli; M Magliuolo; P Simoni; ML Bacchi-Reggiani; E Roda; D Festi

    2006-01-01

    AIM: To simultaneously evaluate the presence of defects in gallbladder and gastric emptying, as well as in intestinal transit in gallstone patients (GS) and the effect of chronic ursodeoxycholic acid (UDCA) administration on these parameters and on serum bile acids and clinical outcome in GS and controls (CTR).METHODS: After a standard liquid test meal, gallbladder and gastric emptying (by ultrasound), oroileal transit time (OI∏) (by an immunoenzymatic technique)and serum bile acids (by HPLC) were evaluated before and after 3 mo of UDCA (12 mg/kg bw/d) or placebo administration in 10 symptomatic GS and 10 matched healthy CTR.RESULTS: OI∏ was longer in GS than in CTR (P <0.0001); UDCA significantly reduced OI∏ in GS (P <0.0001), but not in CTR. GS had longer gastric halfemptying time (t1/2) than CTR (P < 0.0044) at baseline;after UDCA, t1/2 significantly decreased (P < 0.006) in GS but not in CTR. Placebo administration had no effect on gastric emptying and intestinal transit in both GS and CTR.CONCLUSION: The gallstone patient has simultaneous multiple impairments of gallbladder and gastric emptying, as well as of intestinal transit. UDCA administration restores these defects in GS, without any effect in CTR. These results confirm the pathogenetic role of gastrointestinal motility in gallstone disease and suggest an additional mechanism of action for UDCA in reducing bile cholesterol supersaturation.

  11. Defects in mitochondrial and peroxisomal β-oxidation influence virulence in the maize pathogen Ustilago maydis.

    Science.gov (United States)

    Kretschmer, Matthias; Klose, Jana; Kronstad, James W

    2012-08-01

    An understanding of metabolic adaptation during the colonization of plants by phytopathogenic fungi is critical for developing strategies to protect crops. Lipids are abundant in plant tissues, and fungal phytopathogens in the phylum basidiomycota possess both peroxisomal and mitochondrial β-oxidation pathways to utilize this potential carbon source. Previously, we demonstrated a role for the peroxisomal β-oxidation enzyme Mfe2 in the filamentous growth, virulence, and sporulation of the maize pathogen Ustilago maydis. However, mfe2 mutants still caused disease symptoms, thus prompting a more detailed investigation of β-oxidation. We now demonstrate that a defect in the had1 gene encoding hydroxyacyl coenzyme A dehydrogenase for mitochondrial β-oxidation also influences virulence, although its paralog, had2, makes only a minor contribution. Additionally, we identified a gene encoding a polypeptide with similarity to the C terminus of Mfe2 and designated it Mfe2b; this gene makes a contribution to virulence only in the background of an mfe2Δ mutant. We also show that short-chain fatty acids induce cell death in U. maydis and that a block in β-oxidation leads to toxicity, likely because of the accumulation of toxic intermediates. Overall, this study reveals that β-oxidation has a complex influence on the formation of disease symptoms by U. maydis that includes potential metabolic contributions to proliferation in planta and an effect on virulence-related morphogenesis.

  12. Kinetics of wet oxidation of formic acid and acetic acid

    Energy Technology Data Exchange (ETDEWEB)

    Shende, R.V.; Mahajani, V.V. [Univ. of Mumbai (India). Dept. of Chemical Technology

    1997-11-01

    Oxidation of lower molecular weight carboxylic acids such as formic, acetic, glyoxalic, and oxalic acids is often the rate-controlling step during wet oxidation (WO) of an aqueous waste stream exhibiting very high chemical oxygen demand (COD). The kinetics of WO of formic acid was studied in the absence and presence of a cupric sulfate as catalyst in the temperature range 150--240 C and oxygen partial pressure range 0.345--1.380 MPa. Wet oxidation of acetic acid was carried out in the presence of cupric sulfate in the temperature range 215--235 C. Homogeneous copper sulfate was found to be a very good catalyst for oxidation of formic acid and acetic acid.

  13. The defect-centric perspective of device and circuit reliability—From gate oxide defects to circuits

    Science.gov (United States)

    Kaczer, B.; Franco, J.; Weckx, P.; Roussel, Ph. J.; Simicic, M.; Putcha, V.; Bury, E.; Cho, M.; Degraeve, R.; Linten, D.; Groeseneken, G.; Debacker, P.; Parvais, B.; Raghavan, P.; Catthoor, F.; Rzepa, G.; Waltl, M.; Goes, W.; Grasser, T.

    2016-11-01

    As-fabricated (time-zero) variability and mean device aging are nowadays routinely considered in circuit simulations and design. Time-dependent variability (reliability-related variability) is an emerging concern that needs to be considered in circuit design as well. This phenomenon in deeply scaled devices can be best understood within the so-called defect-centric picture in terms of an ensemble of individual defects. The properties of gate oxide defects are discussed. It is further shown how in particular the electrical properties can be used to construct time-dependent variability distributions and can be propagated up to transistor-level circuits.

  14. Folate Deficiency and Folic Acid Supplementation: The Prevention of Neural-Tube Defects and Congenital Heart Defects

    Directory of Open Access Journals (Sweden)

    Andrew E. Czeizel

    2013-11-01

    Full Text Available Diet, particularly vitamin deficiency, is associated with the risk of birth defects. The aim of this review paper is to show the characteristics of common and severe neural-tube defects together with congenital heart defects (CHD as vitamin deficiencies play a role in their origin. The findings of the Hungarian intervention (randomized double-blind and cohort controlled trials indicated that periconceptional folic acid (FA-containing multivitamin supplementation prevented the major proportion (about 90% of neural-tube defects (NTD as well as a certain proportion (about 40% of congenital heart defects. Finally the benefits and drawbacks of three main practical applications of folic acid/multivitamin treatment such as (i dietary intake; (ii periconceptional supplementation; and (iii flour fortification are discussed. The conclusion arrived at is indeed confirmation of Benjamin Franklin’s statement: “An ounce of prevention is better than a pound of care”.

  15. Folic Acid and Birth Defects: A Case Study (Iran

    Directory of Open Access Journals (Sweden)

    Saeid Dastgiri

    2015-07-01

    Full Text Available Background and Objectives : The aim of this study was to evaluate the impact of using folic acid during pregnancy for the reduction of neural tube defects (NTDs in the northwest region of Iran. Material and Methods : In this study, 243 pregnant women that were identified by medical diagnostic tests as having a fetus with some types of congenital anomalies were evaluated. They were referred to Legal Medicine Organization of East Azarbaijan province to get permission for therapeutic termination of pregnancy. Results : The prevalence of NTDs among pregnant women who were referred for therapeutic termination of pregnancy was 24.7%. Consumption of folic acid prevented NTDs by 79% (Odds Ratio = 0.21, CI 95%: 0.12–0.40 and 94% (Odds Ratio = 0.06, CI 95%: 0.03–0.15 compared to pregnancies complicated by other anomalies and normal pregnancies, respectively. Hydrops fetalis, hydrocephaly, Down syndrome and limb anomalies did not have any significant association with use folic acid. Conclusion : Along with the advice for the consumption of folic acid for pregnant women, they should be offered prenatal screening or diagnostic tests to identify fetal abnormalities for possible termination of pregnancy for maternal and child health promotion. ​

  16. Replacement of amino acid sequence features of a- and c-subunits of ATP synthases of Alkaliphilic Bacillus with the Bacillus consensus sequence results in defective oxidative phosphorylation and non-fermentative growth at pH 10.5.

    Science.gov (United States)

    Wang, ZhenXiong; Hicks, David B; Guffanti, Arthur A; Baldwin, Katisha; Krulwich, Terry Ann

    2004-06-18

    Mitchell's (Mitchell, P. (1961) Nature 191, 144-148) chemiosmotic model of energy coupling posits a bulk electrochemical proton gradient (Deltap) as the sole driving force for proton-coupled ATP synthesis via oxidative phosphorylation (OXPHOS) and for other bioenergetic work. Two properties of proton-coupled OXPHOS by alkaliphilic Bacillus species pose a challenge to this tenet: robust ATP synthesis at pH 10.5 that does not correlate with the magnitude of the Deltap and the failure of artificially imposed potentials to substitute for respiration-generated potentials in energizing ATP synthesis at high pH (Krulwich, T. (1995) Mol. Microbiol. 15, 403-410). Here we show that these properties, in alkaliphilic Bacillus pseudofirmus OF4, depend upon alkaliphile-specific features in the proton pathway through the a- and c-subunits of ATP synthase. Site-directed changes were made in six such features to the corresponding sequence in Bacillus megaterium, which reflects the consensus sequence for non-alkaliphilic Bacillus. Five of the six single mutants assembled an active ATPase/ATP synthase, and four of these mutants exhibited a specific defect in non-fermentative growth at high pH. Most of these mutants lost the ability to generate the high phosphorylation potentials at low bulk Deltap that are characteristic of alkaliphiles. The aLys(180) and aGly(212) residues that are predicted to be in the proton uptake pathway of the a-subunit were specifically implicated in pH-dependent restriction of proton flux through the ATP synthase to and from the bulk phase. The evidence included greatly enhanced ATP synthesis in response to an artificially imposed potential at high pH. The findings demonstrate that the ATP synthase of extreme alkaliphiles has special features that are required for non-fermentative growth and OXPHOS at high pH.

  17. The Arabidopsis male-sterile mutant dde2-2 is defective in the ALLENE OXIDE SYNTHASE gene encoding one of the key enzymes of the jasmonic acid biosynthesis pathway

    DEFF Research Database (Denmark)

    von Malek, Bernadette; van der Graaff, Eric; Schneitz, Kay

    2002-01-01

    The Arabidopsis thaliana (L.) Heynh. mutant delayed-dehiscence2-2 (dde2-2) was identified in an En1/Spm1 transposon-induced mutant population screened for plants showing defects in fertility. The dde2-2 mutant allele is defective in the anther dehiscence process and filament elongation and thus...

  18. Retinoic Acid Excess Impairs Amelogenesis Inducing Enamel Defects

    Science.gov (United States)

    Morkmued, Supawich; Laugel-Haushalter, Virginie; Mathieu, Eric; Schuhbaur, Brigitte; Hemmerlé, Joseph; Dollé, Pascal; Bloch-Zupan, Agnès; Niederreither, Karen

    2017-01-01

    Abnormalities of enamel matrix proteins deposition, mineralization, or degradation during tooth development are responsible for a spectrum of either genetic diseases termed Amelogenesis imperfecta or acquired enamel defects. To assess if environmental/nutritional factors can exacerbate enamel defects, we investigated the role of the active form of vitamin A, retinoic acid (RA). Robust expression of RA-degrading enzymes Cyp26b1 and Cyp26c1 in developing murine teeth suggested RA excess would reduce tooth hard tissue mineralization, adversely affecting enamel. We employed a protocol where RA was supplied to pregnant mice as a food supplement, at a concentration estimated to result in moderate elevations in serum RA levels. This supplementation led to severe enamel defects in adult mice born from pregnant dams, with most severe alterations observed for treatments from embryonic day (E)12.5 to E16.5. We identified the enamel matrix proteins enamelin (Enam), ameloblastin (Ambn), and odontogenic ameloblast-associated protein (Odam) as target genes affected by excess RA, exhibiting mRNA reductions of over 20-fold in lower incisors at E16.5. RA treatments also affected bone formation, reducing mineralization. Accordingly, craniofacial ossification was drastically reduced after 2 days of treatment (E14.5). Massive RNA-sequencing (RNA-seq) was performed on E14.5 and E16.5 lower incisors. Reductions in Runx2 (a key transcriptional regulator of bone and enamel differentiation) and its targets were observed at E14.5 in RA-exposed embryos. RNA-seq analysis further indicated that bone growth factors, extracellular matrix, and calcium homeostasis were perturbed. Genes mutated in human AI (ENAM, AMBN, AMELX, AMTN, KLK4) were reduced in expression at E16.5. Our observations support a model in which elevated RA signaling at fetal stages affects dental cell lineages. Thereafter enamel protein production is impaired, leading to permanent enamel alterations. PMID:28111553

  19. Wet oxidation of salicylic acid solutions.

    Science.gov (United States)

    Collado, Sergio; Garrido, Laura; Laca, Adriana; Diaz, Mario

    2010-11-15

    Salicylic acid is a frequent pollutant in several industrial wastewaters. Uncatalyzed wet air oxidation, which is a promising technique for the treatment of phenolic effluents, has not been analyzed yet for the removal of salicylic acid. The effect of different conditions of pH (1.3-12.3), pressure (1.0-4.1 MPa), temperature (413-443 K), and initial concentrations (1.45-14.50 mM) on the wet oxidation of salicylate/salicylic acid solutions have here been investigated. The pH value of the reaction media was found to be a key parameter for the rate of the oxidation process with an optimum at pH 3.1, when the concentrations of salicylic acid and salicylate were similar. The oxidation reaction followed pseudofirst-order kinetics with respect to salicylic acid and 0.82 order with respect to dissolved oxygen. Additionally, the evolution of the color during the wet oxidation was analyzed and discussed in relation with the formation of intermediate compounds. Then, a reaction pathway for the noncatalytic wet oxidation of the salicylic acid was proposed.

  20. Defect-induced selective oxidation of graphene: A first-principles study

    Science.gov (United States)

    Xing, Yu-heng; Lu, Peng-fei; Wang, Jian; Yang, Jin-peng; Chen, Yong-ping

    2017-02-01

    Controlled oxidation of graphene is extremely important for nanopatterning and chemical functionalization. It is generally assumed in experiments that the oxidizing agent in the liquid-phase oxidation first attacks the defective sites in carbon lattices. To explore how the oxidation in the graphene sheet first begins, we have investigated the oxidization process with the structural defect using the density functional theory. Ten reaction pathways in the frame of the transition state theory are considered. We find that the most preferential reaction locus is located at the center of defect. It has also been observed that the preexistence of hydroxyl functional group on the graphene surface substantially decrease energy barrier for oxidization. Such facilitation of oxidation due to hydroxyl can explain how the oxidation process continues after its first oxidation around defects. The uneven redistributions of electron density caused both by defect and by the hydroxyl functional group account for the mechanism of the oxidization process on graphene sheet. Our calculation fully verifies the experimental assumption and is consistent with the recent experimental observations.

  1. Oxidation of phenolic acids by soil iron and manganese oxides

    Energy Technology Data Exchange (ETDEWEB)

    Lehmann, R.G.; Cheng, H.H.; Harsh, J.B.

    Phenolic acids are intermediary metabolites of many aromatic chemicals and may be involved in humus formation, allelopathy, and nutrient availability. Depending on their structures, six phenolic acids were shown to react at different rates with oxidized forms of Fe and Mn in a Palouse soil (fine-silty, mixed, mesic Pachic Ultic Haploxeroll). Increasing methoxy substitution on the aromatic ring of phenolic acids increased the reaction rate. Reaction rate was also increased for longer carboxyl-containing side chains. After 4 h reaction, little of the applied (10 mg kg/sup -1/ soil) p-hydroxybenzoic or p-coumaric acids had reacted, while 0 to 5, 70, 90, and 100% of the vanillic, ferulic, syringic, and sinapic acids, respectively, had reacted. After 72 h under conditions limiting microbial growth, none of the p-hydroxybenzoic, 30% of the p-coumaric, and 50% of the vanillic acids had reacted. The reaction was shown to be predominantly chemical, and not biological, since phenolic acid extractabilities were similar for Palouse soil and for Palouse soil pretreated with LiOBr to remove organic matter. When the Palouse soil was pretreated with a sodium dithionite-citrate solution to remove Fe and Mn oxides, none of the phenolic acids reacted after 1 h. The reaction of sinapic acid with Palouse soil was shown to produce Fe(II) and soluble Mn as reaction products. The reaction of phenolic acids with soil was thus shown to be an oxidation of the phenolic acids, coupled with a reduction of soil Fe and Mn oxides.

  2. Study of bulk and interface defects in silicon oxide with X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Tallarida, Massimo [Brandenburgische Technische Universitaet, Konrad Wachsmann Allee 17, 03046 Cottbus (Germany)], E-mail: tallamas@tu-cottbus.de; Schmeisser, Dieter [Brandenburgische Technische Universitaet, Konrad Wachsmann Allee 17, 03046 Cottbus (Germany)

    2007-11-25

    We show in this work a detailed study of the SiO{sub 2}/Si interface by means of X-ray absorption spectroscopy (XAS). The Si2p absorption edge was measured for both a thick (50 nm) oxide layer and a native (1.5 nm) oxide. From the comparison between these two spectra we can address XAS features to bulk defects in SiO{sub 2} and to interface defects in the native oxide. We demonstrate the capability of XAS of achieving information about interface defects and suggest its use in more complex systems.

  3. Acid monolayer functionalized iron oxide nanoparticle catalysts

    Science.gov (United States)

    Ikenberry, Myles

    Superparamagnetic iron oxide nanoparticle functionalization is an area of intensely active research, with applications across disciplines such as biomedical science and heterogeneous catalysis. This work demonstrates the functionalization of iron oxide nanoparticles with a quasi-monolayer of 11-sulfoundecanoic acid, 10-phosphono-1-decanesulfonic acid, and 11-aminoundecanoic acid. The carboxylic and phosphonic moieties form bonds to the iron oxide particle core, while the sulfonic acid groups face outward where they are available for catalysis. The particles were characterized by thermogravimetric analysis (TGA), transmission electron microscopy (TEM), potentiometric titration, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), inductively coupled plasma optical emission spectrometry (ICP-OES), X-ray photoelectron spectrometry (XPS), and dynamic light scattering (DLS). The sulfonic acid functionalized particles were used to catalyze the hydrolysis of sucrose at 80° and starch at 130°, showing a higher activity per acid site than the traditional solid acid catalyst Amberlyst-15, and comparing well against results reported in the literature for sulfonic acid functionalized mesoporous silicas. In sucrose catalysis reactions, the phosphonic-sulfonic nanoparticles (PSNPs) were seen to be incompletely recovered by an external magnetic field, while the carboxylic-sulfonic nanoparticles (CSNPs) showed a trend of increasing activity over the first four recycle runs. Between the two sulfonic ligands, the phosphonates produced a more tightly packed monolayer, which corresponded to a higher sulfonic acid loading, lower agglomeration, lower recoverability through application of an external magnetic field, and higher activity per acid site for the hydrolysis of starch. Functionalizations with 11-aminoundecanoic acid resulted in some amine groups binding to the surfaces of iron oxide nanoparticles. This amine binding is commonly ignored in iron oxide

  4. Direct Oxidation of Ethene to Acetic Acid

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Direct oxidation of ethene to acetic acid over Pd-SiW12/SiO2 catalysts prepared by several methods was studied. A better method for reducing palladium composition of the catalysts was found. Acetic acid was obtained with selectivity of 82.7% and once-through space time yield (STY) of 257.4 g/h×L.

  5. Mycophenolic Acid-Induced Developmental Defects in Zebrafish Embryos.

    Science.gov (United States)

    Jiang, Ling-Ling; Liu, Mei-Hui; Li, Jian-Ying; He, Zhi-Heng; Li, Huan; Shen, Ning; Wei, Ping; He, Ming-Fang

    2016-11-01

    With the increasing use of mycophenolic acid (MPA) in solid organ transplantation, some clinical studies indicate that it is also a human teratogen. However, it is unknown by which mechanism MPA acts as a teratogen. Mycophenolic acid was a selective blocker of de novo purine synthesis, and its immunosuppressive effect is mediated by the inhibition of inosine monophosphate dehydrogenase, which could be a target for MPA-induced toxicity as well. The aim of our study was to examine the direct influence of MPA exposure on zebrafish (Danio rerio) embryos. Morphological defects including tail curvature and severe pericardial edema in zebrafish embryos caused by MPA (3.7-11.1 µmol/L) were found in a dose-dependent manner. The teratogenic index (25% lethal concentration value (LC25)/no observed adverse effect level ratio) was 16, which indicated MPA as a teratogen. Quantitative polymerase chain reaction analysis revealed that the expression level of impdh1b and impdh2 was significantly reduced by MPA treatment at 8 µmol/L (equals to LC25 level). All the toxic effects could be partially reversed by the addition of 33.3 µmol/L guanosine. Our results indicated that MPA impairs the development of zebrafish embryos via inhibition of impdh activity, which subsequently caused a guanosine nucleotide depletion in vivo.

  6. Fatty acid oxidation and ketogenesis in astrocytes

    Energy Technology Data Exchange (ETDEWEB)

    Auestad, N.

    1988-01-01

    Astrocytes were derived from cortex of two-day-old rat brain and grown in primary culture to confluence. The metabolism of the fatty acids, octanoate and palmitate, to CO{sub 2} in oxidative respiration and to the formation of ketone bodies was examined by radiolabeled tracer methodology. The net production of acetoacetate was also determined by measurement of its mass. The enzymes in the ketogenic pathway were examined by measuring enzymic activity and/or by immunoblot analyses. Labeled CO{sub 2} and labeled ketone bodies were produced from the oxidation of fatty acids labeled at carboxy- and {omega}-terminal carbons, indicating that fatty acids were oxidized by {beta}-oxidation. The results from the radiolabeled tracer studies also indicated that a substantial proportion of the {omega}-terminal 4-carbon unit of the fatty acids bypassed the {beta}-ketothiolase step of the {beta}-oxidation pathway. The ({sup 14}C)acetoacetate formed from the (1-{sup 14}C)labeled fatty acids, obligated to pass through the acetyl-CoA pool, contained 50% of the label at carbon 3 and 50% at carbon 1. In contrast, the ({sup 14}C)acetoacetate formed from the ({omega}-1)labeled fatty acids contained 90% of the label at carbon 3 and 10% at carbon 1.

  7. Folic acid and primary prevention of birth defects.

    Science.gov (United States)

    Taruscio, Domenica; Carbone, Pietro; Granata, Orietta; Baldi, Francesca; Mantovani, Alberto

    2011-01-01

    Birth defects (BDs) are an important public health problem, due to their overall incidence, occurring in 2-3% of live births in European Union. Neural tube defects (NTDs) are among major NTDs, due to their severity and relatively high incidence; in the meanwhile NTDs are also the most effectively preventable BDs to date. In particular, an adequate folic acid (FA) intake reduces both the occurrence and the recurrence of NTDs; FA is the synthetic form of folates, naturally occurring vitamins in a number of foods, especially vegetables. The daily intake of 0.4 mg of FA should be recommended to all women of childbearing age who plan to become pregnant. The Italian Network for Primary Prevention of BDs through FA Promotion has achieved a significant improvement in FA awareness and use in the periconceptional period. Nevertheless, primary prevention of BDs needs to make further progress; the Italian National Centre for Rare Diseases participates in european sureveillance of congenital anomalies (EUROCAT) Joint Action as coordinator of activities on the effectiveness of BDs prevention. Mandatory food fortification with FA has not been introduced in any European country. The health benefits of FA in reducing the risk of NTDs are undisputed; however mechanistic and animal studies suggest a relationship between high FA intakes and increased cancer promotion, while human studies are still inconsistent and inconclusive. A Working Group organized by the European Food Safety Authority pointed out significant uncertainties about fortification safety and the need for more studies; currently, FA intake from fortified foods and supplements should not exceed 1 mg/day in adults. In conclusion, based on up-to-date scientific evidence, the Italian Network strategy pivots on periconceptional supplementation integrated with promotion of healthy eating habits, support to health education, enhancing the role of women in managing life choices about their health and pregnancy and increasing

  8. Defect engineering of the electronic transport through cuprous oxide interlayers

    KAUST Repository

    Fadlallah, Mohamed M.

    2016-06-03

    The electronic transport through Au–(Cu2O)n–Au junctions is investigated using first-principles calculations and the nonequilibrium Green’s function method. The effect of varying the thickness (i.e., n) is studied as well as that of point defects and anion substitution. For all Cu2O thicknesses the conductance is more enhanced by bulk-like (in contrast to near-interface) defects, with the exception of O vacancies and Cl substitutional defects. A similar transmission behavior results from Cu deficiency and N substitution, as well as from Cl substitution and N interstitials for thick Cu2O junctions. In agreement with recent experimental observations, it is found that N and Cl doping enhances the conductance. A Frenkel defect, i.e., a superposition of an O interstitial and O substitutional defect, leads to a remarkably high conductance. From the analysis of the defect formation energies, Cu vacancies are found to be particularly stable, in agreement with earlier experimental and theoretical work.

  9. Prevalent mutations in fatty acid oxidation disorders

    DEFF Research Database (Denmark)

    Gregersen, N; Andresen, B S; Bross, P

    2000-01-01

    UNLABELLED: The mutational spectrum in a given disease-associated gene is often comprised of a large number of different mutations, of which a single or a few are present in a large proportion of diseased individuals. Such prevalent mutations are known in four genes of the fatty acid oxidation: t...... of the disease in question and determination of the carrier frequency in the general population may help in elucidating the penetrance of the genotype. This is exemplified in disorders of mitochondrial fatty acid oxidation....

  10. The influence of initial defects on mechanical stress and deformation distribution in oxidized silicon

    Directory of Open Access Journals (Sweden)

    Kulinich O. A.

    2008-10-01

    Full Text Available The near-surface silicon layers in silicon – dioxide silicon systems with modern methods of research are investigated. It is shown that these layers have compound structure and their parameters depend on oxidation and initial silicon parameters. It is shown the influence of initial defects on mechanical stress and deformation distribution in oxidized silicon.

  11. Neural tube defects in Costa Rica, 1987-2012: origins and development of birth defect surveillance and folic acid fortification.

    Science.gov (United States)

    Barboza-Argüello, María de la Paz; Umaña-Solís, Lila M; Azofeifa, Alejandro; Valencia, Diana; Flores, Alina L; Rodríguez-Aguilar, Sara; Alfaro-Calvo, Thelma; Mulinare, Joseph

    2015-03-01

    Our aim was to provide a descriptive overview of how the birth defects surveillance and folic acid fortification programs were implemented in Costa Rica-through the establishment of the Registry Center for Congenital Anomalies (Centro de Registro de Enfermedades Congénitas-CREC), and fortification legislation mandates. We estimated the overall prevalence of neural tube defects (i.e., spina bifida, anencephaly and encephalocele) before and after fortification captured by CREC. Prevalence was calculated by dividing the total number of infants born with neural tube defects by the total number of live births in the country (1987-2012).A total of 1,170 newborns with neural tube defects were identified from 1987 to 2012 (1992-1995 data excluded); 628 were identified during the baseline pre-fortification period (1987-1991; 1996-1998); 191 during the fortification period (1999-2002); and 351 during the post-fortification time period (2003-2012). The overall prevalence of neural tube defects decreased from 9.8 per 10,000 live-births (95 % CI 9.1-10.5) for the pre-fortification period to 4.8 per 10,000 live births (95 % CI 4.3-5.3) for the post-fortification period. Results indicate a statistically significant (P neural tube defects from the pre-fortification period to the post-fortification period. Folic acid fortification via several basic food sources has shown to be a successful public health intervention for Costa Rica. Costa Rica's experience can serve as an example for other countries seeking to develop and strengthen both their birth defects surveillance and fortification programs.

  12. The prevention of neural tube defects by folic acid supplementation

    Directory of Open Access Journals (Sweden)

    H. W. Hitzeroth

    1993-05-01

    Full Text Available Neural tube defects, in particular spina bifida and anencephaly, are serious and relatively common congenital abnormalities worldwide. They also occur in South Africa and affect all population groups to varying degrees. The overall incidence in South Africa is approximately 1-2 per 1000 newborns. Higher incidences, up to 6 per 1000 newborns have been recorded in certain parts, especially in some rural areas of the country. In total as many as 1500 newborns could be affected by a neural tube defect each year. The precise aetiology of neural tube defects is still unknown.

  13. Prevention of valproic acid-induced neural tube defects by sildenafil citrate.

    Science.gov (United States)

    Tiboni, Gian Mario; Ponzano, Adalisa

    2015-08-15

    This study was undertaken to test the effects of sildenafil citrate (SC), a type 5 phosphodiesterase inhibitor, on valproic acid (VPA)-induced teratogenesis. On gestation day (GD) 8, ICR (CD-1) mice were treated by gastric intubation with SC at 0 (vehicle), 1.0, 2.5, 5.0 or 10mg/kg. One hour later, animals received a teratogenic dose of VPA (600mg/kg) or vehicle. Developmental endpoints were evaluated near the end of gestation. Twenty-eighth percent of fetuses exposed to VPA had neural tube defects (exencephaly). Pretreatment with SC at 2.5, 5.0 or 10mg/kg significantly reduced the rate of VPA-induced exencephaly to 15.9%, 13.7%, and 10.0%, respectively. Axial skeletal defects were observed in 75.8% of VPA-exposed fetuses. Pre-treatment with SC at 10mg/kg, but not at lower doses, significantly decreased the rate of skeletally affected fetuses to 61.6%. These results show that SC, which prolongs nitric oxide (NO) signaling action protects from VPA-induced teratogenesis.

  14. Valproic acid increases conservative homologous recombination frequency and reactive oxygen species formation: a potential mechanism for valproic acid-induced neural tube defects.

    Science.gov (United States)

    Defoort, Ericka N; Kim, Perry M; Winn, Louise M

    2006-04-01

    Valproic acid, a commonly used antiepileptic agent, is associated with a 1 to 2% incidence of neural tube defects when taken during pregnancy; however, the molecular mechanism by which this occurs has not been elucidated. Previous research suggests that valproic acid exposure leads to an increase in reactive oxygen species (ROS). DNA damage due to ROS can result in DNA double-strand breaks, which can be repaired through homologous recombination (HR), a process that is not error-free and can result in detrimental genetic changes. Because the developing embryo requires tight regulation of gene expression to develop properly, we propose that the loss or dysfunction of genes involved in embryonic development through aberrant HR may ultimately cause neural tube defects. To determine whether valproic acid induces HR, Chinese hamster ovary 3-6 cells, containing a neomycin direct repeat recombination substrate, were exposed to valproic acid for 4 or 24 h. A significant increase in HR after exposure to valproic acid (5 and 10 mM) for 24 h was observed, which seems to occur through a conservative HR mechanism. We also demonstrated that exposure to valproic acid (5 and 10 mM) significantly increased intracellular ROS levels, which were attenuated by preincubation with polyethylene glycol-conjugated (PEG)-catalase. A significant change in the ratio of 8-hydroxy-2'-deoxyguanosine/2'-de-oxyguanosine, a measure of DNA oxidation, was not observed after valproic acid exposure; however, preincubation with PEG-catalase significantly blocked the increase in HR. These data demonstrate that valproic acid increases HR frequency and provides a possible mechanism for valproic acid-induced neural tube defects.

  15. Defects and ferromagnetism in transition metal doped zinc oxide

    Science.gov (United States)

    Thapa, Sunil

    Transition metal doped zinc oxide has been studied recently due to its potential application in spintronic devices. The magnetic semiconductor, often called Diluted Magnetic Semiconductors (DMS), has the ability to incorporate both charge and spin into a single formalism. Despite a large number of studies on ferromagnetism in ZnO based DMS and the realization of its room temperature ferromagnetism, there is still a debate about the origin of the ferromagnetism. In this work, the synthesis and characterization of transition metal doped zinc oxide have been carried out. The sol-gel method was used to synthesize thin films, and they were subsequently annealed in air. Characterization of doped zinc oxide films was carried out using the UV-visible range spectrometer, scanning electron microscopy, superconducting quantum interference device (SQUID), x-ray diffraction(XRD) and positron annihilation spectroscopy. Hysteresis loops were obtained for copper and manganese doped zinc oxide, but a reversed hysteresis loop was observed for 2% Al 3% Co doped zinc oxide. The reversed hysteresis loop has been explained using a two-layer model.

  16. Hypochlorous and peracetic acid induced oxidation of dairy proteins.

    Science.gov (United States)

    Kerkaert, Barbara; Mestdagh, Frédéric; Cucu, Tatiana; Aedo, Philip Roger; Ling, Shen Yan; De Meulenaer, Bruno

    2011-02-09

    Hypochlorous and peracetic acids, both known disinfectants in the food industry, were compared for their oxidative capacity toward dairy proteins. Whey proteins and caseins were oxidized under well controlled conditions at pH 8 as a function of the sanitizing concentration. Different markers for protein oxidation were monitored. The results established that the protein carbonyl content was a rather unspecific marker for protein oxidation, which did not allow one to differentiate the oxidant used especially at the lower concentrations. Cysteine, tryptophan, and methionine were proven to be the most vulnerable amino acids for degradation upon hypochlorous and peracetic acid treatment, while tyrosine was only prone to degradation in the presence of hypochlorous acid. Hypochlorous acid induced oxidation gave rise to protein aggregation, while during peracetic acid induced oxidation, no high molecular weight aggregates were observed. Protein aggregation upon hypochlorous acid oxidation could primarily be linked to tryptophan and tyrosine degradation.

  17. Genetic defects in the oxidative phosphorylation (OXPHOS) system.

    NARCIS (Netherlands)

    Janssen, R.J.R.J.; Heuvel, L.P.W.J. van den; Smeitink, J.A.M.

    2004-01-01

    The oxidative phosphorylation (OXPHOS) system consists of five multiprotein complexes and two mobile electron carriers embedded in the lipid bilayer of the mitochondrial inner membrane. With the exception of complex II and the mobile carriers, the other parts of the OXPHOS system are under dual gene

  18. Genetic defects in the oxidative phosphorylation (OXPHOS) system.

    NARCIS (Netherlands)

    Janssen, R.J.R.J.; Heuvel, L.P.W.J. van den; Smeitink, J.A.M.

    2004-01-01

    The oxidative phosphorylation (OXPHOS) system consists of five multiprotein complexes and two mobile electron carriers embedded in the lipid bilayer of the mitochondrial inner membrane. With the exception of complex II and the mobile carriers, the other parts of the OXPHOS system are under dual

  19. [Fortification of food with folic acid diminishes the number of neural tube defects].

    Science.gov (United States)

    Brouwer, I A

    2008-01-26

    A recent study from a research group from Quebec showed a strong decrease in the number of births affected by a neural tube defect since folic acid fortification was introduced in Canada. The prevalence decreased from 1.58 neural tube defects per 1000 births before the introduction of folic acid fortification to 0.86 per 1000 births in the period of complete fortification. Although folic acid fortification of staple food is probably the most effective way to decrease the incidence of neural tube defects, more knowledge about possible health risks should be obtained before fortification is introduced. More research is needed to determine which population groups are at risk of possible negative effects of folic acid fortification and at which level of fortification. Until then, it is important to generate more attention and publicity in order to increase awareness and knowledge concerning folic acid and to promote its use before and after conception.

  20. Slow Replication Fork Velocity of Homologous Recombination-Defective Cells Results from Endogenous Oxidative Stress.

    Science.gov (United States)

    Wilhelm, Therese; Ragu, Sandrine; Magdalou, Indiana; Machon, Christelle; Dardillac, Elodie; Técher, Hervé; Guitton, Jérôme; Debatisse, Michelle; Lopez, Bernard S

    2016-05-01

    Replications forks are routinely hindered by different endogenous stresses. Because homologous recombination plays a pivotal role in the reactivation of arrested replication forks, defects in homologous recombination reveal the initial endogenous stress(es). Homologous recombination-defective cells consistently exhibit a spontaneously reduced replication speed, leading to mitotic extra centrosomes. Here, we identify oxidative stress as a major endogenous source of replication speed deceleration in homologous recombination-defective cells. The treatment of homologous recombination-defective cells with the antioxidant N-acetyl-cysteine or the maintenance of the cells at low O2 levels (3%) rescues both the replication fork speed, as monitored by single-molecule analysis (molecular combing), and the associated mitotic extra centrosome frequency. Reciprocally, the exposure of wild-type cells to H2O2 reduces the replication fork speed and generates mitotic extra centrosomes. Supplying deoxynucleotide precursors to H2O2-exposed cells rescued the replication speed. Remarkably, treatment with N-acetyl-cysteine strongly expanded the nucleotide pool, accounting for the replication speed rescue. Remarkably, homologous recombination-defective cells exhibit a high level of endogenous reactive oxygen species. Consistently, homologous recombination-defective cells accumulate spontaneous γH2AX or XRCC1 foci that are abolished by treatment with N-acetyl-cysteine or maintenance at 3% O2. Finally, oxidative stress stimulated homologous recombination, which is suppressed by supplying deoxynucleotide precursors. Therefore, the cellular redox status strongly impacts genome duplication and transmission. Oxidative stress should generate replication stress through different mechanisms, including DNA damage and nucleotide pool imbalance. These data highlight the intricacy of endogenous replication and oxidative stresses, which are both evoked during tumorigenesis and senescence initiation

  1. International retrospective cohort study of neural tube defects in relation to folic acid recommendations : are the recommendations working?

    NARCIS (Netherlands)

    Botto, LD; Lisi, A; Robert-Gnansia, E; Erickson, JD; Vollset, SE; Mastroiacovo, P; Botting, B; Cocchi, G; de Vigan, C; de Walle, H; Feijoo, M; Irgens, LM; McDonnell, B; Merlob, P; Ritvanen, A; Scarano, G; Siffel, C; Metneki, J; Stoll, C; Smithells, R; Goujard, J

    2005-01-01

    Objective To evaluate the effectiveness of policies and recommendations on folic acid aimed at reducing the occurrence of neural tube defects. Design Retrospective cohort study of births monitored by birth defect registries. Setting 13 birth defects registries monitoring rates of neural tube defects

  2. International retrospective cohort study of neural tube defects in relation to folic acid recommendations : are the recommendations working?

    NARCIS (Netherlands)

    Botto, LD; Lisi, A; Robert-Gnansia, E; Erickson, JD; Vollset, SE; Mastroiacovo, P; Botting, B; Cocchi, G; de Vigan, C; de Walle, H; Feijoo, M; Irgens, LM; McDonnell, B; Merlob, P; Ritvanen, A; Scarano, G; Siffel, C; Metneki, J; Stoll, C; Smithells, R; Goujard, J

    2005-01-01

    Objective To evaluate the effectiveness of policies and recommendations on folic acid aimed at reducing the occurrence of neural tube defects. Design Retrospective cohort study of births monitored by birth defect registries. Setting 13 birth defects registries monitoring rates of neural tube defects

  3. CATALYTIC HYDROGENATION AND OXIDATION OF BIOMASS-DERIVED LEVULINIC ACID

    Directory of Open Access Journals (Sweden)

    Yan Gong

    2011-02-01

    Full Text Available Levulinic acid (LA, 4-oxo-pentanoic acid, is a new platform chemical with various potential uses. In this paper, catalytic hydrogenation and oxidation of levulinic acid were studied. It was shown from experiments that levulinic acid can be hydrogenated to γ-valerolactone (GVL over transition metal catalysts and oxidative-decarboxylated to 2-butanone (methyl-ethyl-ketone, MEK and methyl-vinyl-ketone (MVK by cupric oxide (CuO, cupric oxide/cerium oxide (CuO/CeO2, cupric oxide/ alumina (CuO/ Al2O3, and silver(I/ peroxydisulfate (Ag(I/S2O82-.

  4. Nucleotide precursors prevent folic acid-resistant neural tube defects in the mouse.

    Science.gov (United States)

    Leung, Kit-Yi; De Castro, Sandra C P; Savery, Dawn; Copp, Andrew J; Greene, Nicholas D E

    2013-09-01

    Closure of the neural tube during embryogenesis is a crucial step in development of the central nervous system. Failure of this process results in neural tube defects, including spina bifida and anencephaly, which are among the most common birth defects worldwide. Maternal use of folic acid supplements reduces risk of neural tube defects but a proportion of cases are not preventable. Folic acid is thought to act through folate one-carbon metabolism, which transfers one-carbon units for methylation reactions and nucleotide biosynthesis. Hence suboptimal performance of the intervening reactions could limit the efficacy of folic acid. We hypothesized that direct supplementation with nucleotides, downstream of folate metabolism, has the potential to support neural tube closure. Therefore, in a mouse model that exhibits folic acid-resistant neural tube defects, we tested the effect of specific combinations of pyrimidine and purine nucleotide precursors and observed a significant protective effect. Labelling in whole embryo culture showed that nucleotides are taken up by the neurulating embryo and incorporated into genomic DNA. Furthermore, the mitotic index was elevated in neural folds and hindgut of treated embryos, consistent with a proposed mechanism of neural tube defect prevention through stimulation of cellular proliferation. These findings may provide an impetus for future investigations of supplemental nucleotides as a means to prevent a greater proportion of human neural tube defects than can be achieved by folic acid alone.

  5. Regulating infrared photoresponses in reduced graphene oxide phototransistors by defect and atomic structure control.

    Science.gov (United States)

    Chang, Haixin; Sun, Zhenhua; Saito, Mitsuhiro; Yuan, Qinghong; Zhang, Han; Li, Jinhua; Wang, Zhongchang; Fujita, Takeshi; Ding, Feng; Zheng, Zijian; Yan, Feng; Wu, Hongkai; Chen, Mingwei; Ikuhara, Yuichi

    2013-07-23

    Defects play significant roles in properties of graphene and related device performances. Most studies of defects in graphene focus on their influences on electronic or luminescent optical properties, while controlling infrared optoelectronic performance of graphene by defect engineering remains a challenge. In the meantime, pristine graphene has very low infrared photoresponses of ~0.01 A/W due to fast photocarrier dynamics. Here we report regulating infrared photoresponses in reduced graphene oxide phototransistors by defect and atomic structure control for the first time. The infrared optoelectronic transport and photocurrent generation are significantly influenced and well controlled by oxygenous defects and structures in reduced graphene oxide. Moreover, remarkable infrared photoresponses are observed in photoconductor devices based on reduced graphene oxide with an external responsivity of ~0.7 A/W, at least over one order of magnitude higher than that from pristine graphene. External quantum efficiencies of infrared devices reach ultrahigh values of ~97%, which to our knowledge is one of the best efficiencies for infrared photoresponses from nonhybrid, pure graphene or graphene-based derivatives. The flexible infrared photoconductor devices demonstrate no photoresponse degradation even after 1000 bending tests. The results open up new routes to control optoelectronic behaviors of graphene for high-performance devices.

  6. Defects in oxide surfaces studied by atomic force and scanning tunneling microscopy

    Directory of Open Access Journals (Sweden)

    Thomas König

    2011-01-01

    Full Text Available Surfaces of thin oxide films were investigated by means of a dual mode NC-AFM/STM. Apart from imaging the surface termination by NC-AFM with atomic resolution, point defects in magnesium oxide on Ag(001 and line defects in aluminum oxide on NiAl(110, respectively, were thoroughly studied. The contact potential was determined by Kelvin probe force microscopy (KPFM and the electronic structure by scanning tunneling spectroscopy (STS. On magnesium oxide, different color centers, i.e., F0, F+, F2+ and divacancies, have different effects on the contact potential. These differences enabled classification and unambiguous differentiation by KPFM. True atomic resolution shows the topography at line defects in aluminum oxide. At these domain boundaries, STS and KPFM verify F2+-like centers, which have been predicted by density functional theory calculations. Thus, by determining the contact potential and the electronic structure with a spatial resolution in the nanometer range, NC-AFM and STM can be successfully applied on thin oxide films beyond imaging the topography of the surface atoms.

  7. Synthesis and structural characterization of defect spinels in the Lithium-Manganese-Oxide system

    CSIR Research Space (South Africa)

    Thackeray, MM

    1993-10-01

    Full Text Available Lithium-manganese-oxides prepared at moderate temperatures are under investigation as insertion electrodes for rechargeable lithium batteries. The structures of two defect-spinel compounds synthesised by the reaction of MnCO3 and Li2CO3 at 400...

  8. Synthesis and structural characterization of defect spinels in the lithium-manganese-oxide system

    CSIR Research Space (South Africa)

    Thackeray, MM

    1993-10-01

    Full Text Available Lithium-manganese-oxides prepared at moderate temperatures are under investigation as insertion electrodes for rechargeable lithium batteries. The structures of two defect-spinel compounds synthesized by the reaction of MnCO3 and Li2CO3 at 400°C...

  9. Multivitamins, Folic Acid and Birth Defects: Knowledge, Beliefs and Behaviors of Hispanic Women in North Carolina

    Science.gov (United States)

    deRosset, Leslie; Mullenix, Amy; Zhang, Lei

    2009-01-01

    Background: Consumption of folic acid prior to conception can prevent up to 70% of neural tube defect (NTD)-affected pregnancies. In 1992, the U.S. Public Health Service (USPHS) issued a recommendation that all women of childbearing age capable of becoming pregnant consume 400 [mu]g of folic acid daily to reduce their risk for a NTD-affected…

  10. The nature of paramagnetic defects in tin (IV) oxide

    Energy Technology Data Exchange (ETDEWEB)

    Ivanovskaya, M., E-mail: ivanovskaya@bsu.by [Research Institute for Physical Chemical Problems, Belarusian State University, Leningradskaya Str., 14, 220030 Minsk (Belarus); Ovodok, E., E-mail: ovodokea@gmail.com [Research Institute for Physical Chemical Problems, Belarusian State University, Leningradskaya Str., 14, 220030 Minsk (Belarus); Golovanov, V. [South-Ukrainian University, Staroportofrankovskaya Str., 26, 65008 Odessa (Ukraine)

    2015-08-18

    Highlights: • EPR signal at g = 1.8–1.9 (D) was studied in SnO{sub 2} prepared under different conditions. • Conditions appropriate for detection of D signal and parameters of them were defined. • Structure of paramagnetic center (PC) attributed to the D signal was proposed. • The PC is a complex of oxygen vacancies with entrapped electrons near SnO{sub 2} surface. - Abstract: The nature of paramagnetic centers which are responsible for the EPR signal at g = 1.8–1.9 in tin (IV) oxide was studied. Polycrystalline SnO{sub 2} samples were obtained by sol–gel method and by thermal treatment of the precursors containing tin atoms in different oxidation states. The parameters of the EPR spectra recorded after heat treatment of the samples in air, oxygen and hydrogen atmospheres, and in vacuum were analyzed. The observed parameters of the EPR spectra do not allow to assign the paramagnetic center with g = 1.8–1.9 to Sn{sup 3+} center. The structure of the paramagnetic center attributed to the EPR signal at g = 1.8–1.9 was proposed. The proposed structure of the paramagnetic center includes a complex of oxygen vacancies at (1 0 1) plane of rutile-type SnO{sub 2} lattice.

  11. [Neural tube defects and folic acid: a historical overview of a highly successful preventive intervention].

    Science.gov (United States)

    Vásquez, Adriana Ordoñez; Suarez-Obando, Fernando

    2015-12-01

    This article gives a broad overview of part of the historical evolution of medical knowledge about neural tube defects (NTD) and the discovery of vitamin B9 or folic acid, as well as some relevant research events that, over the course of several centuries, defined the relationships between the understanding of central nervous system embryology, the discovery of the vitamin, the correlation between folic acid and cell proliferation and lastly the development of preventive measures for this type of defects. This narrative allows us to examine historically relevant concepts underlying clinical actions with a populational impact that prevent NTDs via folic acid consumption prior to conception.

  12. Interfacial strain and defects in asymmetric Fe-Mn oxide hybrid nanoparticles

    Science.gov (United States)

    Mayence, Arnaud; Wéry, Madeleine; Tran, Dung Trung; Wetterskog, Erik; Svedlindh, Peter; Tai, Cheuk-Wai; Bergström, Lennart

    2016-07-01

    Asymmetric Fe-Mn oxide hybrid nanoparticles have been obtained by a seed-mediated thermal decomposition-based synthesis route. The use of benzyl ether as the solvent was found to promote the orientational growth of Mn1-xO onto the iron oxide nanocube seeds yielding mainly dimers and trimers whereas 1-octadecene yields large nanoparticles. HRTEM imaging and HAADF-STEM tomography performed on dimers show that the growth of Mn1-xO occurs preferentially along the edges of iron oxide nanocubes where both oxides share a common crystallographic orientation. Fourier filtering and geometric phase analysis of dimers reveal a lattice mismatch of 5% and a large interfacial strain together with a significant concentration of defects. The saturation magnetization is lower and the coercivity is higher for the Fe-Mn oxide hybrid nanoparticles compared to the iron oxide nanocube seeds.Asymmetric Fe-Mn oxide hybrid nanoparticles have been obtained by a seed-mediated thermal decomposition-based synthesis route. The use of benzyl ether as the solvent was found to promote the orientational growth of Mn1-xO onto the iron oxide nanocube seeds yielding mainly dimers and trimers whereas 1-octadecene yields large nanoparticles. HRTEM imaging and HAADF-STEM tomography performed on dimers show that the growth of Mn1-xO occurs preferentially along the edges of iron oxide nanocubes where both oxides share a common crystallographic orientation. Fourier filtering and geometric phase analysis of dimers reveal a lattice mismatch of 5% and a large interfacial strain together with a significant concentration of defects. The saturation magnetization is lower and the coercivity is higher for the Fe-Mn oxide hybrid nanoparticles compared to the iron oxide nanocube seeds. Electronic supplementary information (ESI) available: Materials characterization, powder X-ray diffraction, EFTEM images, EELS spectra, HAADF-STEM. See DOI: 10.1039/c6nr01373b

  13. Oxide Defect Engineering Enables to Couple Solar Energy into Oxygen Activation.

    Science.gov (United States)

    Zhang, Ning; Li, Xiyu; Ye, Huacheng; Chen, Shuangming; Ju, Huanxin; Liu, Daobin; Lin, Yue; Ye, Wei; Wang, Chengming; Xu, Qian; Zhu, Junfa; Song, Li; Jiang, Jun; Xiong, Yujie

    2016-07-20

    Modern development of chemical manufacturing requires a substantial reduction in energy consumption and catalyst cost. Sunlight-driven chemical transformation by metal oxides holds great promise for this goal; however, it remains a grand challenge to efficiently couple solar energy into many catalytic reactions. Here we report that defect engineering on oxide catalyst can serve as a versatile approach to bridge light harvesting with surface reactions by ensuring species chemisorption. The chemisorption not only spatially enables the transfer of photoexcited electrons to reaction species, but also alters the form of active species to lower the photon energy requirement for reactions. In a proof of concept, oxygen molecules are activated into superoxide radicals on defect-rich tungsten oxide through visible-near-infrared illumination to trigger organic aerobic couplings of amines to corresponding imines. The excellent efficiency and durability for such a highly important process in chemical transformation can otherwise be virtually impossible to attain by counterpart materials.

  14. Kinetics of wet air oxidation of glyoxalic acid and oxalic acid

    Energy Technology Data Exchange (ETDEWEB)

    Shende, R.V.; Mahajani, V.V. (Univ. of Bombay (India). Dept. of Chemical Technology)

    1994-12-01

    Oxidation of lower molecular weight monobasic and dibasic acids such as formic acid, acetic acid, glyoxalic acid, and oxalic acid is often the rate-controlling step during wet air oxidation (WAO) of an aqueous waste stream exhibiting very high chemical oxygen demand (COD). The kinetics of WAO of glyoxalic acid and oxalic acid was studied in absence and presence of a cupric sulfate catalyst in the temperature range of 120--245 C and oxygen partial pressure of 0.345--1.380 MPa. The wet oxidation of oxalic acid was found to require more severe conditions as compared to glyoxalic acid. The reaction mechanism and kinetic model have been discussed.

  15. Modulating fatty acid oxidation in heart failure.

    Science.gov (United States)

    Lionetti, Vincenzo; Stanley, William C; Recchia, Fabio A

    2011-05-01

    In the advanced stages of heart failure, many key enzymes involved in myocardial energy substrate metabolism display various degrees of down-regulation. The net effect of the altered metabolic phenotype consists of reduced cardiac fatty oxidation, increased glycolysis and glucose oxidation, and rigidity of the metabolic response to changes in workload. Is this metabolic shift an adaptive mechanism that protects the heart or a maladaptive process that accelerates structural and functional derangement? The question remains open; however, the metabolic remodelling of the failing heart has induced a number of investigators to test the hypothesis that pharmacological modulation of myocardial substrate utilization might prove therapeutically advantageous. The present review addresses the effects of indirect and direct modulators of fatty acid (FA) oxidation, which are the best pharmacological agents available to date for 'metabolic therapy' of failing hearts. Evidence for the efficacy of therapeutic strategies based on modulators of FA metabolism is mixed, pointing to the possibility that the molecular/biochemical alterations induced by these pharmacological agents are more complex than originally thought. Much remains to be understood; however, the beneficial effects of molecules such as perhexiline and trimetazidine in small clinical trials indicate that this promising therapeutic strategy is worthy of further pursuit.

  16. Photoluminescence emission of nanoporous anodic aluminum oxide films prepared in phosphoric acid

    Science.gov (United States)

    Nourmohammadi, Abolghasem; Asadabadi, Saeid Jalali; Yousefi, Mohammad Hasan; Ghasemzadeh, Majid

    2012-12-01

    The photoluminescence emission of nanoporous anodic aluminum oxide films formed in phosphoric acid is studied in order to explore their defect-based subband electronic structure. Different excitation wavelengths are used to identify most of the details of the subband states. The films are produced under different anodizing conditions to optimize their emission in the visible range. Scanning electron microscopy investigations confirm pore formation in the produced layers. Gaussian analysis of the emission data indicates that subband states change with anodizing parameters, and various point defects can be formed both in the bulk and on the surface of these nanoporous layers during anodizing.

  17. Cold-storage defects in butter and their relation to the autoxidation of unsaturated fatty acids

    NARCIS (Netherlands)

    Badings, H.T.

    1970-01-01

    In this thesis investigations are described of the identification of aroma compounds which are formed as a result of oxidative deterioration of butter during cold storage, producing a typical trainy (fishy) off-flavour. As these flavour defects are caused chiefly by autoxidative breakdown of

  18. wet oxidation of maleic acid by a pumice supported copper

    African Journals Online (AJOL)

    Mgina

    materials were tested in a wet oxidation of maleic acid using air or hydrogen peroxide as an oxidant. Results ... textile, pharmaceuticals, paper and pulp .... Fourier Transform Infrared (FTIR). The ... to analysis and then run at room temperature.

  19. Advanced oxidation of acid and reactive dyes

    DEFF Research Database (Denmark)

    Arslan-Alaton, I.; Gursoy, B.H.; Schmidt, Jens Ejbye

    2008-01-01

    M) for 10:hsp sp="0.25" min Fenton treatment at pH 3, resulting in reduced chemical oxygen demand and dissolved organic carbon removal efficiencies; only acetate was detected as a stable dye oxidation end product. During anaerobic digestion, 100, 29% and no inhibition in methane production was observed...... for the untreated blue, red and orange dyes, respectively. The inhibitory effect of the blue reactive dye on methane production was ∼21% after Fenton treatment. Neither untreated nor treated dyes exhibited an inhibitory effect on denitrification. Aerobic glucose degradation was inhibited by 23-29% by untreated dyes......The effect of untreated and Fenton-treated acid dyes (C.I. Acid Red 183 and C.I. Acid Orange 51) and a reactive dye (C.I. Reactive Blue 4) on aerobic, anoxic and anaerobic processes was investigated. The optimum Fe2+:H2O2 molar ratio was selected as 1:5 (4:hsp sp="0.25" mM:20:hsp sp="0.25"m...

  20. Spectroscopic properties of doped and defective semiconducting oxides from hybrid density functional calculations.

    Science.gov (United States)

    Di Valentin, Cristiana; Pacchioni, Gianfranco

    2014-11-18

    CONSPECTUS: Very rarely do researchers use metal oxides in their pure and fully stoichiometric form. In most of the countless applications of these compounds, ranging from catalysis to electronic devices, metal oxides are either doped or defective because the most interesting chemical, electronic, optical, and magnetic properties arise when foreign components or defects are introduced in the lattice. Similarly, many metal oxides are diamagnetic materials and do not show a response to specific spectroscopies such as electron paramagnetic resonance (EPR) spectroscopy. However, doped or defective oxides may exhibit an interesting and informative paramagnetic behavior. Doped and defective metal oxides offer an expanding range of applications in contemporary condensed matter science; therefore researchers have devoted enormous effort to the understanding their physical and chemical properties. The interplay between experiment and computation is particularly useful in this field, and contemporary simulation techniques have achieved high accuracies with these materials. In this Account, we show how the direct comparison between spectroscopic experimental and computational data for some selected and relevant materials provides ways to understand and control these complex systems. We focus on the EPR properties and electronic transitions that arise from the presence of dopants and defects in bulk metal oxide materials. We analyze and compare the effect of nitrogen doping in TiO2 and ZnO (two semiconducting oxides) and MgO (a wide gap insulator) and examine the effect of oxygen deficiency in the semiconducting properties of TiO2-x, ZnO1-x, and WO3-x materials. We chose these systems because of their relevance in applications including photocatalysis, touch screens, electrodes in magnetic random access memories, and smart glasses. Density functional theory (DFT) provides the general computational framework used to illustrate the electronic structure of these systems. However

  1. Oxidized alginate hydrogels for bone morphogenetic protein-2 delivery in long bone defects.

    Science.gov (United States)

    Priddy, Lauren B; Chaudhuri, Ovijit; Stevens, Hazel Y; Krishnan, Laxminarayanan; Uhrig, Brent A; Willett, Nick J; Guldberg, Robert E

    2014-10-01

    Autograft treatment of large bone defects and fracture non-unions is complicated by limited tissue availability and donor site morbidity. Polymeric biomaterials such as alginate hydrogels provide an attractive tissue engineering alternative due to their biocompatibility, injectability, and tunable degradation rates. Irradiated RGD-alginate hydrogels have been used to deliver proteins such as bone morphogenetic protein-2 (BMP-2), to promote bone regeneration and restoration of function in a critically sized rat femoral defect model. However, slow degradation of irradiated alginate hydrogels may impede integration and remodeling of the regenerated bone to its native architecture. Oxidation of alginate has been used to promote degradation of alginate matrices. The objective of this study was to evaluate the effects of alginate oxidation on BMP-2 release and bone regeneration. We hypothesized that oxidized-irradiated alginate hydrogels would elicit an accelerated release of BMP-2, but degrade faster in vivo, facilitating the formation of higher quality, more mature bone compared to irradiated alginate. Indeed, oxidation of irradiated alginate did accelerate in vitro BMP-2 release. Notably, the BMP-2 retained within both constructs was bioactive at 26days, as observed by induction of alkaline phosphatase activity and positive Alizarin Red S staining of MC3T3-E1 cells. From the in vivo study, robust bone regeneration was observed in both groups through 12weeks by radiography, micro-computed tomography analyses, and biomechanical testing. Bone mineral density was significantly greater for the oxidized-irradiated alginate group at 8weeks. Histological analyses of bone defects revealed enhanced degradation of oxidized-irradiated alginate and suggested the presence of more mature bone after 12weeks of healing.

  2. Oxidized alginate hydrogels for BMP-2 delivery in long bone defects

    Science.gov (United States)

    Priddy, Lauren B; Chaudhuri, Ovijit; Stevens, Hazel Y; Krishnan, Laxminarayanan; Uhrig, Brent A; Willett, Nick J; Guldberg, Robert E

    2014-01-01

    Autograft treatment of large bone defects and fracture non-unions is complicated by limited tissue availability and donor site morbidity. Polymeric biomaterials such as alginate hydrogels provide an attractive tissue engineering alternative due to their biocompatibility, injectability, and tunable degradation rates. Irradiated RGD-alginate hydrogels have been used to deliver proteins such as bone morphogenetic protein-2 (BMP-2), to promote bone regeneration and restoration of function in a critically sized rat femoral defect model. However, slow degradation of irradiated alginate hydrogels may impede integration and remodeling of the regenerated bone to its native architecture. Oxidation of alginate has been used to promote degradation of alginate matrices. The objective of this study was to evaluate the effects of alginate oxidation on BMP-2 release and bone regeneration. We hypothesized that oxidized-irradiated alginate hydrogels would elicit an accelerated release of BMP-2, but degrade faster in vivo, facilitating the formation of higher quality, more mature bone compared to irradiated alginate. Indeed, oxidation of irradiated alginate did accelerate in vitro BMP-2 release. Notably, the BMP-2 retained within both constructs was bioactive at 26 days, as observed by induction of alkaline phosphatase activity and positive Alizarin Red S staining of MC3T3-E1 cells. From the in vivo study, robust bone regeneration was observed in both groups through 12 weeks by radiography, micro-CT analyses, and biomechanical testing. Bone mineral density (BMD) was significantly greater for the oxidized-irradiated alginate group at 8 weeks. Histological analyses of bone defects revealed enhanced degradation of oxidized-irradiated alginate and suggested the presence of more mature bone after 12 weeks of healing. PMID:24954001

  3. Reduced coupling of oxidative phosphorylation in vivo precedes electron transport chain defects due to mild oxidative stress in mice.

    Directory of Open Access Journals (Sweden)

    Michael P Siegel

    Full Text Available Oxidative stress and mitochondrial function are at the core of many degenerative conditions. However, the interaction between oxidative stress and in vivo mitochondrial function is unclear. We used both pharmacological (2 week paraquat (PQ treatment of wild type mice and transgenic (mice lacking Cu, Zn-superoxide dismutase (SOD1(-/- models to test the effect of oxidative stress on in vivo mitochondrial function in skeletal muscle. Magnetic resonance and optical spectroscopy were used to measure mitochondrial ATP and oxygen fluxes and cell energetic state. In both models of oxidative stress, coupling of oxidative phosphorylation was significantly lower (lower P/O at rest in vivo in skeletal muscle and was dose-dependent in the PQ model. Despite this reduction in efficiency, in vivo mitochondrial phosphorylation capacity (ATPmax was maintained in both models, and ex vivo mitochondrial respiration in permeabilized muscle fibers was unchanged following PQ treatment. In association with the reduced P/O, PQ treatment led to a dose-dependent reduction in PCr/ATP ratio and increased phosphorylation of AMPK. These results indicate that oxidative stress uncouples oxidative phosphorylation in vivo and results in energetic stress in the absence of defects in the mitochondrial electron transport chain.

  4. Physical defect formation in few layer graphene-like carbon on metals: influence of temperature, acidity, and chemical functionalization.

    Science.gov (United States)

    Schumacher, Christoph M; Grass, Robert N; Rossier, Michael; Athanassiou, Evagelos K; Stark, Wendelin J

    2012-03-06

    A systematical examination of the chemical stability of cobalt metal nanomagnets with a graphene-like carbon coating is used to study the otherwise rather elusive formation of nanometer-sized physical defects in few layer graphene as a result of acid treatments. We therefore first exposed the core-shell nanomaterial to well-controlled solutions of altering acidity and temperature. The release of cobalt into these solutions over time offered a simple tool to monitor the progress of particle degradation. The results suggested that the oxidative damage of the graphene-like coatings was the rate-limiting step during particle degradation since only fully intact or entirely emptied carbon shells were found after the experiments. If ionic noble metal species were additionally present in the acidic solutions, the noble metal was found to reduce on the surface of specific, defective particles. The altered electrochemical gradients across the carbon shells were however not found to lead to a faster release of cobalt from the particles. The suggested mechanistic insight was further confirmed by the covalent chemical functionalization of the particle surface with chemically inert aryl species, which leads to an additional thickening of the shells. This leads to reduced cobalt release rates as well as slower noble metal reduction rates depending on the augmentation of the shell thickness.

  5. Role of masking oxide on silicon in processes of defect generation at formation of SIMOX structures

    CERN Document Server

    Askinazi, A Y; Miloglyadova, L V

    2002-01-01

    One investigated into Si-SiO sub 2 structures formed by implantation of oxygen ions into silicon (SIMOX-technology) by means of techniques based on measuring of high-frequency volt-farad characteristics and by means of electroluminescence. One determined existence of electrically active centres and of luminescence centres in the formed oxide layer near boundary with silicon. One clarified the role SiO sub 2 masking layer in silicon in defect generation under formation of the masked oxide layer. One established dependence of concentration of electrically active and luminescence centres on thickness of masking layer

  6. Band alignment and defects of the diamond zinc oxide heterojunction; Bandstruktur und Defekte der Diamant-Zinkoxid-Heterostruktur

    Energy Technology Data Exchange (ETDEWEB)

    Geithner, Peter

    2008-09-12

    Zinc oxide films were grown on diamond single crystals by rf sputtering of zinc oxide. The valence and conduction band offset was determined by photoelectron spectroscopy. A deep defect occurring in the zinc oxide films on diamond was characterized by cathodoluminescence spectroscopy. (orig.)

  7. Advanced Multi-Component Defect Cluster Oxide Doped Zirconia-Yttria Thermal Barrier Coatings

    Science.gov (United States)

    Zhu, Dongming; Miller, Robert A.

    2003-01-01

    The advantages of using ceramic thermal barrier coatings in gas turbine engine hot sections include increased fuel efficiency and improved engine reliability. However, current thermal barrier coatings will not have the low thermal conductivity and necessary sintering resistance under higher operating temperatures and thermal gradients required by future advanced ultra efficient and low emission aircraft engines. In this paper, a novel oxide defect cluster design approach is described for achieving low thermal conductivity and excellent thermal stability of the thermal barrier coating systems. This approach utilizes multi-component rare earth and other metal cluster oxide dopants that are incorporated in the zirconia-yttna based systems, thus significantly reducing coating thermal conductivity and sintering resistance by effectively promoting the formation of thermodynamically stable, essentially immobile defect clusters and/or nanoscale phases. The performance of selected plasma-sprayed cluster oxide thermal barrier coating systems has been evaluated. The advanced multi-component thermal barrier coating systems were found to have significantly lower initial and long-term thermal conductivities, and better high temperature stability. The effect of oxide cluster dopants on coating thermal conductivity, sintering resistance, oxide grain growth behavior and durability will be discussed.

  8. Final Technical Report for DE-SC0001878 [Theory and Simulation of Defects in Oxide Materials

    Energy Technology Data Exchange (ETDEWEB)

    Chelikowsky, James R. [University of Texas at Austin

    2014-04-14

    We explored a wide variety of oxide materials and related problems, including materials at the nanoscale and generic problems associated with oxide materials such as the development of more efficient computational tools to examine these materials. We developed and implemented methods to understand the optical and structural properties of oxides. For ground state properties, our work is predominantly based on pseudopotentials and density functional theory (DFT), including new functionals and going beyond the local density approximation (LDA): LDA+U. To study excited state properties (quasiparticle and optical excitations), we use time dependent density functional theory, the GW approach, and GW plus Bethe-Salpeter equation (GW-BSE) methods based on a many-body Green function approaches. Our work focused on the structural, electronic, optical and magnetic properties of defects (such as oxygen vacancies) in hafnium oxide, titanium oxide (both bulk and clusters) and related materials. We calculated the quasiparticle defect states and charge transition levels of oxygen vacancies in monoclinic hafnia. we presented a milestone G0W0 study of two of the crystalline phases of dye-sensitized TiO{sub 2} clusters. We employed hybrid density functional theory to examine the electronic structure of sexithiophene/ZnO interfaces. To identify the possible effect of epitaxial strain on stabilization of the ferromagnetic state of LaCoO{sub 3} (LCO), we compare the total energy of the magnetic and nonmagnetic states of the strained theoretical bulk structure.

  9. Chemically derived defects in zinc oxide nanocrystals and their enhanced photo-electrocatalytic activities.

    Science.gov (United States)

    Prakash, Anand; Bahadur, D

    2014-10-21

    This paper reports the influence of surface defects on the photocatalytic degradation of methylene blue (MB) for zinc oxide (ZnO) nanocrystals (NCs) synthesized in different organic solvents. A simple chemical approach has been adopted for the promotion of oxygen vacancies in pristine ZnO using solvents namely dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP) and dimethylsulfoxide (DMSO). This alters the growth of NCs through the promotion of oxygen vacancies depending on the fact that the solvent with minimum viscosity supports faster nucleation and growth exhibiting maximum surface defects. DMF with minimum viscosity results in largest particle size and superior photocatalytic activity. Further, X-ray diffraction, UV-visible reflectance spectroscopy and transmission electron microscopy confirm that the DMF supports the faster growth of NCs as compared to NMP and DMSO. Electron paramagnetic resonance, Raman, X-ray photoelectron, and photoluminescence spectroscopies confirm different states of oxygen vacancies in the NCs and their dependence on the nature of solvents. The photocatalytic activities of these NCs were investigated against the degradation of MB as a model dye. The results show that the oxygen defects at the surface of NCs are more responsible for higher photocatalytic activity than the specific surface area of NCs. The electrochemical investigations of MB degradation suggest that these defects upon interaction with MB influence the storage capacity and charge-discharge profiles of NCs. During degradation, MB passivates these defects, which has been explained in terms of increased charge-discharge time and storage capacity.

  10. A defect in amino acid transport of filamentous Escherichia coli induced by penicillin.

    OpenAIRE

    内藤, 伸明; 友近, 健一; 口分田,晃; 塩出,純二; 金政, 泰弘

    1983-01-01

    This paper describes a new type of penicillin action on the cytoplasmic membrane of Escherichia coli. The ability of filamentous cells to uptake amino acids induced by low concentrations of penicillin increased with cell elongation. This defect in amino acid transport was mostly observed on the substrate of the osmotic shock resistant transport system. Penicillin treatment, however, did not disturb the other membrane functions such as the uptake of α-D-methyl glucopyranoside and triphenylmeth...

  11. Folic acid supplementation influences the distribution of neural tube defect subtypes : A registry-based study

    NARCIS (Netherlands)

    Bergman, J. E. H.; Otten, E.; Verheij, J. B. G. M.; de Walle, H. E. K.

    2016-01-01

    Periconceptional folic acid (FA) reduces neural tube defect (NTD) risk, but seems to have a varying effect per NTD subtype. We aimed to study the effect of FA supplementation on NTD subtype distribution using data from EUROCAT Northern Netherlands. We included all birth types with non-syndromal NTDs

  12. Folic Acid for the Prevention of Neural Tube Defects : US Preventive Services Task Force Recommendation Statement

    NARCIS (Netherlands)

    Calonge, Ned; Petitti, Diana B.; DeWitt, Thomas G.; Dietrich, Allen J.; Gregory, Kimberly D.; Grossman, David; Isham, George; LeFevre, Michael L.; Leipzig, Rosanne M.; Marion, Lucy N.; Melnyk, Bernadette; Moyer, Virginia A.; Ockene, Judith K.; Sawaya, George F.; Schwartz, J. Sanford; Wilt, Timothy

    2009-01-01

    Description: In 1996, the U. S. Preventive Services Task Force (USPSTF) recommended that all women planning or capable of pregnancy take a multivitamin supplement containing folic acid for the prevention of neural tube defects. This recommendation is an update of the 1996 USPSTF recommendation. Meth

  13. Living on the edge : substrate competition explains loss of robustness in mitochondrial fatty-acid oxidation disorders

    NARCIS (Netherlands)

    van Eunen, Karen; Volker-Touw, Catharina M L; Gerding, Albert; Bleeker, Aycha; Wolters, Justina C; Rijt, van Willemijn; Martines, Anne-Claire M F; Niezen-Koning, Klary E.; Heiner, Rebecca M.; Permentier, Hjalmar; Groen, Albert K; Reijngoud, Dirk-Jan; Derks, Terry G J; Bakker, Barbara M

    2016-01-01

    BACKGROUND: Defects in genes involved in mitochondrial fatty-acid oxidation (mFAO) reduce the ability of patients to cope with metabolic challenges. mFAO enzymes accept multiple substrates of different chain length, leading to molecular competition among the substrates. Here, we combined computation

  14. Living on the edge : Substrate competition explains loss of robustness in mitochondrial fatty-acid oxidation disorders

    NARCIS (Netherlands)

    van Eunen, Karen; Volker-Touw, Catharina M L; Gerding, Albert; Bleeker, Aycha; Wolters, Justina C.; van Rijt, Willemijn J.; Martines, Anne Claire M F; Niezen-Koning, Klary E.; Heiner, Rebecca M.; Permentier, Hjalmar; Groen, Albert K.; Reijngoud, Dirk Jan; Derks, Terry G J; Bakker, Barbara M.

    2016-01-01

    Background: Defects in genes involved in mitochondrial fatty-acid oxidation (mFAO) reduce the ability of patients to cope with metabolic challenges. mFAO enzymes accept multiple substrates of different chain length, leading to molecular competition among the substrates. Here, we combined computation

  15. Kinetics of wet oxidation of propionic and 3-hydroxypropionic acids

    Energy Technology Data Exchange (ETDEWEB)

    Shende, R.V.; Levec, J. [National Inst. of Chemistry, Ljubljana (Slovenia). Lab. for Catalysis and Chemical Reaction Engineering]|[Univ. of Ljubljana (Slovenia). Dept. of Chemical Engineering

    1999-07-01

    Oxidation of aqueous solutions of 3-hydroxypropionic (3-HPA) and propionic acids (PA) was studied in a titanium high-pressure reactor at 280--310 C using oxygen partial pressures between 10 and 45 bar. Oxidation of both acids was found to obey first-order kinetic with respect to their concentrations as well as to their lumped TOC concentrations. Oxidation rate revealed a half order dependence with respect to oxygen for oxidation of both acids. In the case of 3-HPA oxidation, the activation energy was found to be 135 kJ/mol, and it was 140 kJ/mol when lumped concentration TOC was used. The activation energy for PA oxidation is 150 kJ/mol, and it is slightly higher, 158 kJ/mol, for TOC reduction. Almost complete conversion of 3-HPA was achieved at 300 C after 1 h, whereas 95% conversion of PA acid was obtained at 310 C after 3 h. During oxidation of 3-HPA, 3-oxopropionic and acetic acids were identified as intermediate products. Oxidation of PA yielded acetic and formic acids as intermediates; at oxygen partial pressures above 25 bar and 310 C, the formation of acetic acid was appreciably reduced. In both cases, however, direct oxidation to carbon dioxide and water was found to be the main reaction route.

  16. The effect of valinomycin in fibroblasts from patients with fatty acid oxidation disorders

    Energy Technology Data Exchange (ETDEWEB)

    Ndukwe Erlingsson, Uzochi Chimdinma [Division of Medical Genetics, Department of Pediatrics, University of Utah, 2C412 SOM, 50 North Mario Capecchi Drive, Salt Lake City, UT 84132 (United States); Iacobazzi, Francesco [Division of Medical Genetics, Department of Pediatrics, University of Utah, 2C412 SOM, 50 North Mario Capecchi Drive, Salt Lake City, UT 84132 (United States); Department of Basic Medical Sciences, University of Bari, Piazza Giulio Cesare 11, Policlinico, I-70124 Bari (Italy); Liu, Aiping [ARUP Institute for Clinical and Experimental Pathology, ARUP Laboratories, 500 Chipeta Way, Salt Lake City, UT 84108 (United States); Ardon, Orly; Pasquali, Marzia [Division of Medical Genetics, Department of Pediatrics, University of Utah, 2C412 SOM, 50 North Mario Capecchi Drive, Salt Lake City, UT 84132 (United States); ARUP Institute for Clinical and Experimental Pathology, ARUP Laboratories, 500 Chipeta Way, Salt Lake City, UT 84108 (United States); Department of Pathology, University of Utah, Salt Lake City, UT 84132 (United States); Longo, Nicola, E-mail: Nicola.Longo@hsc.utah.edu [Division of Medical Genetics, Department of Pediatrics, University of Utah, 2C412 SOM, 50 North Mario Capecchi Drive, Salt Lake City, UT 84132 (United States); ARUP Institute for Clinical and Experimental Pathology, ARUP Laboratories, 500 Chipeta Way, Salt Lake City, UT 84108 (United States); Department of Pathology, University of Utah, Salt Lake City, UT 84132 (United States)

    2013-08-09

    Highlights: •Valinomycin can cause mitochondrial stress and stimulate fatty acid oxidation. •Cells with VLCAD deficiency fail to increase fatty acid oxidation in response to valinomycin. •Response to valinomycin can help in the diagnosis of VLCAD deficiency. -- Abstract: Disorders of the carnitine cycle and of the beta oxidation spiral impair the ability to obtain energy from fats at time of fasting and stress. This can result in hypoketotic hypoglycemia, cardiomyopathy, cardiac arrhythmia and other chronic medical problems. The in vitro study of fibroblasts from patients with these conditions is impaired by their limited oxidative capacity. Here we evaluate the capacity of valinomycin, a potassium ionophore that increases mitochondrial respiration, to increase the oxidation of fatty acids in cells from patients with inherited fatty acid oxidation defects. The addition of valinomycin to fibroblasts decreased the accumulation of the lipophilic cation tetraphenylphosphonium (TPP{sup +}) at low concentrations due to the dissipation of the mitochondrial membrane potential. At higher doses, valinomycin increased TPP{sup +} accumulation due to the increased potassium permeability of the plasma membrane and subsequent cellular hyperpolarization. The incubation of normal fibroblasts with valinomycin increased [{sup 14}C]-palmitate oxidation (measured as [{sup 14}C]O{sub 2} release) in a dose-dependent manner. By contrast, valinomycin failed to increase palmitate oxidation in fibroblasts from patients with very long chain acyl CoA dehydrogenase (VLCAD) deficiency. This was not observed in fibroblasts from patients heterozygous for this condition. These results indicate that valinomycin can increase fatty acid oxidation in normal fibroblasts and could be useful to differentiate heterozygotes from patients affected with VLCAD deficiency.

  17. Non-destructive functionalisation for atomic layer deposition of metal oxides on carbon nanotubes: effect of linking agents and defects

    Science.gov (United States)

    Kemnade, N.; Shearer, C. J.; Dieterle, D. J.; Cherevan, A. S.; Gebhardt, P.; Wilde, G.; Eder, D.

    2015-02-01

    The hybridisation of metal oxides and nanocarbons has created a promising new class of functional materials for environmental and sustainable energy applications. The performance of such hybrids can be further improved by rationally designing interfaces and morphologies. Atomic layer deposition (ALD) is among the most powerful techniques for the controlled deposition of inorganic compounds, due to its ability to form conformal coatings on porous substrates at low temperatures with high surface sensitivity and atomic control of film thickness. The hydrophobic nature of the nanocarbon surface has so far limited the applicability of ALD on CNTs. Herein we investigate the role of structural defects in CNTs, both intrinsic and induced by acid treatment, on coverage, uniformity and crystallinity of ZnO coatings. Furthermore, we demonstrate the potential of small aromatic molecules, including benzyl alcohol (BA), naphthalene carboxylic acid (NA) and pyrene carboxylic acid (PCA), as active nucleation sites and linking agents. Importantly, only PCA exhibits sufficiently strong interactions with the pristine CNT surface to withstand desorption under reaction conditions. Thus, PCA enables a versatile and non-destructive alternative route for the deposition of highly uniform metal oxide coatings onto pristine CNTs via ALD over a wide temperature range and without the typical surface corrosion induced by covalent functionalisation. Importantly, preliminary tests demonstrated that the improved morphology obtained with PCA has indeed considerably increased the hybrid's photocatalytic activity towards hydrogen evolution via sacrificial water splitting. The concept demonstrated in this work is transferable to a wide range of other inorganic compounds including metal oxides, metal (oxy)nitrides and metal chalcogenides on a variety of nanocarbons.The hybridisation of metal oxides and nanocarbons has created a promising new class of functional materials for environmental and

  18. Mutant Huntingtin and Elusive Defects in Oxidative Metabolism and Mitochondrial Calcium Handling.

    Science.gov (United States)

    Brustovetsky, Nickolay

    2016-07-01

    Elongation of a polyglutamine (polyQ) stretch in huntingtin protein (Htt) is linked to Huntington's disease (HD) pathogenesis. The mutation in Htt correlates with neuronal dysfunction in the striatum and cerebral cortex and eventually leads to neuronal cell death. The exact mechanisms of the injurious effect of mutant Htt (mHtt) on neurons are not completely understood but might include aberrant gene transcription, defective autophagy, abnormal mitochondrial biogenesis, anomalous mitochondrial dynamics, and trafficking. In addition, deficiency in oxidative metabolism and defects in mitochondrial Ca(2+) handling are considered essential contributing factors to neuronal dysfunction in HD and, consequently, in HD pathogenesis. Since the discovery of the mutation in Htt, the questions whether mHtt affects oxidative metabolism and mitochondrial Ca(2+) handling and, if it does, what mechanisms could be involved were in focus of numerous investigations. However, despite significant research efforts, the detrimental effect of mHtt and the mechanisms by which mHtt might impair oxidative metabolism and mitochondrial Ca(2+) handling remain elusive. In this paper, I will briefly review studies aimed at clarifying the consequences of mHtt interaction with mitochondria and discuss experimental results supporting or arguing against the mHtt effects on oxidative metabolism and mitochondrial Ca(2+) handling.

  19. Kinetics and Mechanism of Oxidation of Phenyl Acetic Acid and Dl-Mandelic Acid by Permanganate in Acid Medium

    Directory of Open Access Journals (Sweden)

    B.Syama Sundar

    2014-06-01

    Full Text Available Kinetics of oxidation of phenyl acetic acid and DL- Mandelic acid by potassium permanganate in aqueous acetic acid and perchloric acid mixture reveals that the kinetic orders are first order in oxidant, first order in H+ and zero order in substrate for phenyl acetic acid. DL-Mandelic acid exhibits first order in oxidant and zero order in substrate. The results are rationalised by a mechanism involving intermediate formation of mandelic acid in case of Phenyl acetic acid and ester formation with Mn (VII in case of DL-Mandelic acid. The following order of reactivity is observed: DL-Mandelic acid > Phenyl acetic acid. The high reactivity of DL-Mandelic acid over phenyl acetic acid may be due to different mechanisms operating with the two substrates and benzaldehyde is the final product in both the cases.

  20. Identifying environmental risk factors for human neural tube defects before and after folic acid supplementation

    Directory of Open Access Journals (Sweden)

    Li Xinhu

    2009-10-01

    Full Text Available Abstract Background Birth defects are a major cause of infant mortality and disability in many parts of the world. Neural tube defects (NTDs are one of the most common types of birth defects. In 2001, the Chinese population and family planning commission initiated a national intervention program for the prevention of birth defects. A key step in the program was the introduction of folic acid supplementation. Of interest in the present study was to determine whether folic acid supplementation has the same protective effect on NTDs under various geographical and socioeconomic conditions within the Chinese population and the nature in which the influence of environmental factors varied after folic acid supplementation. Methods In this study, Heshun was selected as the region of interest as a surrogate for helping to answer some of the questions raised in this study on the impact of the intervention program. Spatial filtering in combination with GIS software was used to detect annual potential clusters from 1998 to 2005 in Heshun, and Kruskal-wallis test and multivariate regression were applied to identify the environmental risk factors for NTDs among various regions. Results In 1998, a significant (p Conclusion This suggests that the government needs to adapt the intervention measures according to local conditions. More attention needs to be paid to the poor and to people living in areas near coal mines.

  1. Intrinsic point defects in zinc oxide. Modeling of structural, electronic, thermodynamic and kinetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Erhart, P.

    2006-07-01

    The present dissertation deals with the modeling of zinc oxide on the atomic scale employing both quantum mechanical as well as atomistic methods. The first part describes quantum mechanical calculations based on density functional theory of intrinsic point defects in ZnO. To begin with, the geometric and electronic structure of vacancies and oxygen interstitials is explored. In equilibrium oxygen interstitials are found to adopt dumbbell and split interstitial configurations in positive and negative charge states, respectively. Semi-empirical self-interaction corrections allow to improve the agreement between the experimental and the calculated band structure significantly; errors due to the limited size of the supercells can be corrected by employing finite-size scaling. The effect of both band structure corrections and finite-size scaling on defect formation enthalpies and transition levels is explored. Finally, transition paths and barriers for the migration of zinc as well as oxygen vacancies and interstitials are determined. The results allow to interpret diffusion experiments and provide a consistent basis for developing models for device simulation. In the second part an interatomic potential for zinc oxide is derived. To this end, the Pontifix computer code is developed which allows to fit analytic bond-order potentials. The code is subsequently employed to obtain interatomic potentials for Zn-O, Zn-Zn, and O-O interactions. To demonstrate the applicability of the potentials, simulations on defect production by ion irradiation are carried out. (orig.)

  2. A polarity-induced defect mechanism for conductivity and magnetism at polar-nonpolar oxide interfaces.

    Science.gov (United States)

    Yu, Liping; Zunger, Alex

    2014-10-13

    The discovery of conductivity and magnetism at the polar-nonpolar interfaces of insulating nonmagnetic oxides such as LaAlO3 and SrTiO3 has raised prospects for attaining interfacial functionalities absent in the component materials. Yet, the microscopic origin of such emergent phenomena remains unclear, posing obstacles to design of improved functionalities. Here we present first principles calculations of electronic and defect properties of LaAlO3/SrTiO3 interfaces and reveal a unifying mechanism for the origins of both conductivity and magnetism. We demonstrate that the polar discontinuity across the interface triggers thermodynamically the spontaneous formation of certain defects that in turn cancel the polar field induced by the polar discontinuity. The ionization of the spontaneously formed surface oxygen vacancy defects leads to interface conductivity, whereas the unionized Ti-on-Al antisite defects lead to interface magnetism. The proposed mechanism suggests practical design principles for inducing and controlling both conductivity and magnetism at general polar-nonpolar interfaces.

  3. Tuning the reactivity of Ru nanoparticles by defect engineering of the reduced graphene oxide support

    KAUST Repository

    Liu, Xin

    2014-01-01

    We systematically investigated the electronic structure of Ru nanoparticles supported on various local structures on reduced graphene oxide (rGO) by first-principles-based calculations. We showed that Ru nanoparticles prefer to nucleate at these localized defect structures on rGO, which act as strong trapping sites for Ru nanoparticles and inhibit their aggregation. The binding of Ru nanoparticles to rGO, which is dependent on these local defect structures and correlates with the interfacial charge transfer, determines the electronic structure of the composites. Further study reveals that the performance of these composites against oxygen adsorption changes proportionally with the shift of the d-band center of the nanoparticles. The correlation between the defect structures on rGO and the reactivity of the composites suggests that controlled modification of the graphenic support by defect engineering would be an efficient way to fabricate new transition metal/rGO composites with high stability and desired reactivity. This journal is © the Partner Organisations 2014.

  4. Room-temperature single-photon emission from zinc oxide nanoparticle defects and their in vitro photostable intrinsic fluorescence

    Directory of Open Access Journals (Sweden)

    Chung Kelvin

    2017-01-01

    Full Text Available Zinc oxide (ZnO is a promising semiconductor that is suitable for bioimaging applications due to its intrinsic defect fluorescence. However, ZnO generally suffers from poor photostability. We report room-temperature single-photon emission from optical defects found in ZnO nanoparticles (NPs formed by ion implantation followed by thermal oxidation in a silica substrate. We conduct a thorough investigation into the photophysics of a particularly bright defect and identify other single emitters within the NPs. Photostability was observed when the NPs were removed from the growth substrate and taken up by skin cells for in vitro imaging.

  5. Room-temperature single-photon emission from zinc oxide nanoparticle defects and their in vitro photostable intrinsic fluorescence

    Science.gov (United States)

    Chung, Kelvin; Karle, Timothy J.; Khalid, Asma; Abraham, Amanda N.; Shukla, Ravi; Gibson, Brant C.; Simpson, David A.; Djurišic, Aleksandra B.; Amekura, Hiroshi; Tomljenovic-Hanic, Snjezana

    2017-01-01

    Zinc oxide (ZnO) is a promising semiconductor that is suitable for bioimaging applications due to its intrinsic defect fluorescence. However, ZnO generally suffers from poor photostability. We report room-temperature single-photon emission from optical defects found in ZnO nanoparticles (NPs) formed by ion implantation followed by thermal oxidation in a silica substrate. We conduct a thorough investigation into the photophysics of a particularly bright defect and identify other single emitters within the NPs. Photostability was observed when the NPs were removed from the growth substrate and taken up by skin cells for in vitro imaging.

  6. Intrinsic Defect Engineering of Cuprous Oxide to Enhance Electrical Transport Properties for Photovoltaic Applications

    Energy Technology Data Exchange (ETDEWEB)

    Lloyd, Michael A.; Siah, Sin-Cheng; Brandt, Riley E.; Serdy, James; Johnston, Steve W.; Lee, Yun Seog; Buonassisi, Tonio

    2014-06-08

    Intrinsic point-defect species in cuprous oxide films are manipulated based on their thermodynamic properties via the implementation of a controlled annealing process. A wide range of electrical properties is demonstrated, with a window suitable for high-quality solar cell devices. A variation of carrier concentration over two orders of magnitude is demonstrated. Minority carrier lifetime is investigated by means of microwave photoconductance decay measurements, demonstrating a strong correlation with carrier concentration. Spectrally resolved photoluminescence yields are analyzed to provide insight into lifetime limiting mechanisms as a function of Cu2O processing parameters. Hall measurements of carrier mobility and concentration are taken at room temperature to provide insight into the effect of these processing conditions on net ionized defect concentration.

  7. Correlating defect induced ferromagnetism and gas sensing properties of undoped tin oxide sensors

    Science.gov (United States)

    Kamble, Vinayak B.; Umarji, Arun M.

    2014-06-01

    A correlation between gas sensing properties and defect induced Room Temperature Ferromagnetism (RTFM) is demonstrated in non-stoichiometric SnO2 prepared by solution combustion method. The presence of oxygen vacancies (VO), confirmed by RTFM is identified as the primary factor for enhanced gas sensing effect. The as-prepared SnO2 shows high saturation magnetization of ˜0.018 emu/g as compared to ˜0.002 and ˜0.0005 emu/g in annealed samples and SnO2 prepared by precipitation respectively. The SnO2 prepared by precipitation which is an equilibrium method of synthesis shows lesser defects compared to the combustion product and hence exhibits lesser sensitivity in spite of smaller crystallite size. The study utilizes RTFM as a potential tool to characterize metal oxide gas sensors and recognizes the significance of oxygen vacancies in sensing mechanism over the microstructure.

  8. Folic acid and neural tube defects: are Jordanian pregnant women aware?

    Science.gov (United States)

    Alebous, H D; Ma'aita, M E; Alkhazaleh, F A

    2014-01-01

    To assess Jordanian pregnant women's awareness of folic acid and its contribution to neural tube defects (NTDs) prevention and to their folic acid intake. One thousand pregnant women were interviewed about their knowledge of folic acid for NTDs prevention and their folic acid intake using a questionnaire. Of 1,000 women surveyed, 93.4% reported hearing of folic acid and 30.3% of NTDs. Only 16.2% knew that folic acid can reduce NTDs risk; 42.0% of those aware of folic acid believed it should be taken periconceptionally but only 16.9% did so. The most common information sources on folic acid were physicians (82.8%). Whereas a large percentage of pregnant Jordanian women were aware of folic acid, only a small proportion are aware that it prevents NTDs and should be taken periconceptionally. Also, there was a gap between awareness, knowledge, and intake of folic acid. Awareness and knowledge of NTDs was less prevalent among Jordanian women. Despite the efforts that have been undertaken, further effort is required to educate Jordanian women about folic acid contribution to NTDs prevention.

  9. Lipids and lipoteichoic acid of autolysis-defective Streptococcus faecium strains.

    Science.gov (United States)

    Shungu, D L; Cornett, J B; Shockman, G D

    1980-06-01

    Two of four previously isolated autolysis-defective mutants of Streptococcus faecium (Streptococcus faecalis ATCC 9790) incorporated substantially more [14C]glycerol into lipids and lipoteichoic acid than did the parent strain. Consistent with increased accumulation of lipids and lipoteichoic acid, significantly higher levels of phosphorus were found in the corresponding fractions of the two mutant strains than in the wild type. Although the autolysis-defective mutant strains contained the same assortment of lipids as the wild type, the relative amount of [14C]glycerol incorporated into diphosphatidylglycerol increased, accompanied by a decreased fraction of phosphatidylglycerol. These results suggested that increased cellular content of two types of substances, acylated lipoteichoic acid and lipids (notably diphosphatidylglycerol), which previously had been shown to be potent inhibitors of the N-acetylmuramoylhydrolase of this species, contributed to the autolysis-defective phenotype of these mutants. Consistent with this interpretation are observations that (i) cerulenin inhibition of fatty acid synthesis increased the rates of benzylpenicillin-induced cellular lysis and that (ii) Triton X-100 or Zwittergent 3-14 treatment could reveal the presence of otherwise cryptic but substantial levels of the active form of the autolysin in cells of three of four mutants and of the proteinase-activable latent form in all four mutants.

  10. [Folic acid use by pregnant women in Israel for preventing neural tube defects].

    Science.gov (United States)

    Gil, Z; Aran, A; Friedman, O; Beni-Adani, L; Constantini, S

    2000-12-01

    Spina bifida and anencephaly are the most common, serious malformations in neural tube defects (NTD). Randomized trials in the last 2 decades have demonstrated that folic acid, 0.4 mg/d, reduces the incidence of NTD by more than 50%. We investigated the use of folic acid and multivitamins containing folic acid in childbearing women. Of 221 women interviewed, 67 (30%) regularly took pills containing 0.4 mg folic acid. Women with higher educational levels were more likely to take multivitamins with folic acid than were the less educated (p = 0.05). Of the women who took folic acid, only 5 (7.5%) used separate folic acid tablets, before and during their pregnancy. The rest used multivitamins containing folic acid. The 5 women who took folic acid separately were college-educated and nonreligious, and they took multivitamins in addition (p > 0.05). Of the women interviewed, 58 (26.2%) were Bedouin of the Negev. 24 (41.4%) of them took pills containing folic acid on a regular basis. This percentage is higher than that in the Jewish women in the study who took folic acid for prevention of NTD (17%; p = 0.038). Most of the women took folic acid after the first trimester. Only a minority took daily periconceptional folic acid. Multivitamins containing 0.4 mg of folic acid were more popular than folic acid tablets alone. This study emphasizes the need for continuing efforts to increase consumption of folic acid and awareness of its benefits among women of childbearing age.

  11. Selenium dioxide catalysed oxidation of acetic acid hydrazide by bromate in aqueous hydrochloric acid medium

    Indian Academy of Sciences (India)

    R S Yalgudre; G S Gokavi

    2012-07-01

    Selenium dioxide catalysed acetic acid hydrazide oxidation by bromate was studied in hydrochloric acid medium. The order in oxidant concentration, substrate and catalyst were found to be unity. Increasing hydrogen ion concentration increases the rate of the reaction due to protonation equilibria of the oxidant. The mechanism of the reaction involves prior complex formation between the catalyst and substrate, hydrazide, followed by its oxidation by diprotonated bromate in a slow step. Acetic acid was found to be the oxidation product. Other kinetic data like effect of solvent polarity and ionic strength on the reaction support the proposed mechanism.

  12. Oxidative stress and nucleic acid oxidation in patients with chronic kidney disease.

    Science.gov (United States)

    Sung, Chih-Chien; Hsu, Yu-Chuan; Chen, Chun-Chi; Lin, Yuh-Feng; Wu, Chia-Chao

    2013-01-01

    Patients with chronic kidney disease (CKD) have high cardiovascular mortality and morbidity and a high risk for developing malignancy. Excessive oxidative stress is thought to play a major role in elevating these risks by increasing oxidative nucleic acid damage. Oxidative stress results from an imbalance between reactive oxygen/nitrogen species (RONS) production and antioxidant defense mechanisms and can cause vascular and tissue injuries as well as nucleic acid damage in CKD patients. The increased production of RONS, impaired nonenzymatic or enzymatic antioxidant defense mechanisms, and other risk factors including gene polymorphisms, uremic toxins (indoxyl sulfate), deficiency of arylesterase/paraoxonase, hyperhomocysteinemia, dialysis-associated membrane bioincompatibility, and endotoxin in patients with CKD can inhibit normal cell function by damaging cell lipids, arachidonic acid derivatives, carbohydrates, proteins, amino acids, and nucleic acids. Several clinical biomarkers and techniques have been used to detect the antioxidant status and oxidative stress/oxidative nucleic acid damage associated with long-term complications such as inflammation, atherosclerosis, amyloidosis, and malignancy in CKD patients. Antioxidant therapies have been studied to reduce the oxidative stress and nucleic acid oxidation in patients with CKD, including alpha-tocopherol, N-acetylcysteine, ascorbic acid, glutathione, folic acid, bardoxolone methyl, angiotensin-converting enzyme inhibitor, and providing better dialysis strategies. This paper provides an overview of radical production, antioxidant defence, pathogenesis and biomarkers of oxidative stress in patients with CKD, and possible antioxidant therapies.

  13. Oxidative Stress and Nucleic Acid Oxidation in Patients with Chronic Kidney Disease

    Directory of Open Access Journals (Sweden)

    Chih-Chien Sung

    2013-01-01

    Full Text Available Patients with chronic kidney disease (CKD have high cardiovascular mortality and morbidity and a high risk for developing malignancy. Excessive oxidative stress is thought to play a major role in elevating these risks by increasing oxidative nucleic acid damage. Oxidative stress results from an imbalance between reactive oxygen/nitrogen species (RONS production and antioxidant defense mechanisms and can cause vascular and tissue injuries as well as nucleic acid damage in CKD patients. The increased production of RONS, impaired nonenzymatic or enzymatic antioxidant defense mechanisms, and other risk factors including gene polymorphisms, uremic toxins (indoxyl sulfate, deficiency of arylesterase/paraoxonase, hyperhomocysteinemia, dialysis-associated membrane bioincompatibility, and endotoxin in patients with CKD can inhibit normal cell function by damaging cell lipids, arachidonic acid derivatives, carbohydrates, proteins, amino acids, and nucleic acids. Several clinical biomarkers and techniques have been used to detect the antioxidant status and oxidative stress/oxidative nucleic acid damage associated with long-term complications such as inflammation, atherosclerosis, amyloidosis, and malignancy in CKD patients. Antioxidant therapies have been studied to reduce the oxidative stress and nucleic acid oxidation in patients with CKD, including alpha-tocopherol, N-acetylcysteine, ascorbic acid, glutathione, folic acid, bardoxolone methyl, angiotensin-converting enzyme inhibitor, and providing better dialysis strategies. This paper provides an overview of radical production, antioxidant defence, pathogenesis and biomarkers of oxidative stress in patients with CKD, and possible antioxidant therapies.

  14. Wet oxidation kinetics of refractory low molecular mass carboxylic acids

    Energy Technology Data Exchange (ETDEWEB)

    Shende, R.V.; Levec, J.

    1999-10-01

    Wet oxidation kinetics of aqueous solutions of formic, acetic, oxalic, and glyoxalic acids was studied in a titanium autoclave at a temperature range of 150--320 C and oxygen partial pressures between 8 and 60 bar. Oxidation reactions obeyed a first-order kinetics with respect to concentration of all substrates. On the basis of acid concentration decay, the activation energy for acetic, oxalic, and glyoxalic acid oxidation was 178, 137, and 97 kJ/mol, respectively; whereas on the total organic carbon (TOC) conversion basis, these values were slightly higher, namely 182, 141, and 104 kJ/mol. The activation energy for formic acid took a unique value of 149 kJ/mol regardless of the type of concentration used. The rate of oxidation was proportional to a square root of oxygen concentration (partial pressure) for acetic, formic, and oxalic acids, whereas it was linearly proportional for glyoxalic acid. When sufficiently high oxygen partial pressure was applied ({ge}22 bar), the individual acid conversion in a mixture of these acids was well predicted by the rate expression derived for that acid. The lumped TOC concentration of mixtures did not obey a first-order kinetic behavior, although underlying TOC kinetics for each individual acid was linear. The oxidation results are also discussed in a view of speculated reaction pathways and the reactor material.

  15. Evidence for oxidative stress and defective antioxidant response in guinea pigs with tuberculosis.

    Directory of Open Access Journals (Sweden)

    Gopinath S Palanisamy

    Full Text Available The development of granulomatous inflammation with caseous necrosis is an important but poorly understood manifestation of tuberculosis in humans and some animal models. In this study we measured the byproducts of oxidative stress in granulomatous lesions as well as the systemic antioxidant capacity of BCG vaccinated and non-vaccinated guinea pigs experimentally infected with Mycobacterium tuberculosis. In non-vaccinated guinea pigs, oxidative stress was evident within 2 weeks of infection as measured by a decrease in the serum total antioxidant capacity and blood glutathione levels accompanied by an increase in malondialdehyde, a byproduct of lipid peroxidation, within lesions. Despite a decrease in total and reduced blood glutathione concentrations, there was an increase in lesion glutathione by immunohistochemistry in response to localized oxidative stress. In addition there was an increase in the expression of the host transcription factor nuclear erythroid 2 p45-related factor 2 (Nrf2, which regulates several protein and non-proteins antioxidants, including glutathione. Despite the increase in cytoplasmic expression of Nrf2, immunohistochemical staining revealed a defect in Nrf2 nuclear translocation within granulomatous lesions as well as a decrease in the expression of the Nrf2-regulated antioxidant protein NQO1. Treating M. tuberculosis-infected guinea pigs with the antioxidant drug N-acetyl cysteine (NAC partially restored blood glutathione concentrations and the serum total antioxidant capacity. Treatment with NAC also decreased spleen bacterial counts, as well as decreased the lung and spleen lesion burden and the severity of lesion necrosis. These data suggest that the progressive oxidative stress during experimental tuberculosis in guinea pigs is due in part to a defect in host antioxidant defenses, which, we show here, can be partially restored with antioxidant treatment. These data suggest that the therapeutic strategies that

  16. Folic acid and the decline in neural tube defects in Arkansas.

    Science.gov (United States)

    Mosley, Bridget S; Hobbs, Charlotte A; Flowers, Bettye S; Smith, Veronica; Robbins, James M

    2007-04-01

    Folic acid has been shown to reduce the risk of pregnancies affected by neural tube defects (NTDs) by as much as 70%. Cereal grains sold in the U.S. have been fortified with folic acid since 1998. The Arkansas Reproductive Health Monitoring System and the Arkansas Folic Acid Coalition have encouraged use of folic acid and monitored the impact of increased consumption of folic acid among Arkansans. NTDs in Arkansas have declined 40% since intervention programs were implemented. The greatest decline has been observed among white and Hispanic women. Efforts to encourage folic acid consumption should continue to target Arkansas women. NTDs include anencephaly and spina bifida. These birth defects result from incomplete closure of the fetal neural tube during the first month of pregnancy. Infants with anencephaly are born without all or most of their brain and die within a few days of life. Infants with spina bifida have varying degrees of impairment ranging from little noticeable disability to severe, lifelong disability. Folic acid, when taken in supplement form has been shown to reduce the risk of a pregnancy affected by a neural tube defect by as much as 70%. As a result of this finding, the U.S. Federal Drug Administration mandated that cereal grains sold in this country be fortified with at least 140 mcg of folic acid per 100 grams of grain by January 1, 1998. Prior to mandatory fortification, the March of Dimes and the U.S. Public Health Service released statements encouraging all women of reproductive age who are capable of becoming pregnant to take 400 mcg 'of synthetic folic acid daily. The Arkansas Reproductive Health Monitoring System (ARHMS) has monitored rates of NTDs in Arkansas since 1980. ARHMS is the lead agency of the Arkansas Folic Acid Coalition whose mission is to encourage folic acid use among all Arkansas women of reproductive age. In this report, we summarize efforts by ARHMS and the Arkansas Folic Acid Coalition to increase the awareness and

  17. Acetic Acid bacteria: physiology and carbon sources oxidation.

    Science.gov (United States)

    Mamlouk, Dhouha; Gullo, Maria

    2013-12-01

    Acetic acid bacteria (AAB) are obligately aerobic bacteria within the family Acetobacteraceae, widespread in sugary, acidic and alcoholic niches. They are known for their ability to partially oxidise a variety of carbohydrates and to release the corresponding metabolites (aldehydes, ketones and organic acids) into the media. Since a long time they are used to perform specific oxidation reactions through processes called "oxidative fermentations", especially in vinegar production. In the last decades physiology of AAB have been widely studied because of their role in food production, where they act as beneficial or spoiling organisms, and in biotechnological industry, where their oxidation machinery is exploited to produce a number of compounds such as l-ascorbic acid, dihydroxyacetone, gluconic acid and cellulose. The present review aims to provide an overview of AAB physiology focusing carbon sources oxidation and main products of their metabolism.

  18. Economic burden of neural tube defects and impact of prevention with folic acid: a literature review.

    Science.gov (United States)

    Yi, Yunni; Lindemann, Marion; Colligs, Antje; Snowball, Claire

    2011-11-01

    Neural tube defects (NTDs) are the second most common group of serious birth defects. Although folic acid has been shown to reduce effectively the risk of NTDs and measures have been taken to increase the awareness, knowledge, and consumption of folic acid, the full potential of folic acid to reduce the risk of NTDs has not been realized in most countries. To understand the economic burden of NTDs and the economic impact of preventing NTDs with folic acid, a systematic review was performed on relevant studies. A total of 14 cost of illness studies and 10 economic evaluations on prevention of NTDs with folic acid were identified. Consistent findings were reported across all of the cost of illness studies. The lifetime direct medical cost for patients with NTDs is significant, with the majority of cost being for inpatient care, for treatment at initial diagnosis in childhood, and for comorbidities in adult life. The lifetime indirect cost for patients with spina bifida is even greater due to increased morbidity and premature mortality. Caregiver time costs are also significant. The results from the economic evaluations demonstrate that folic acid fortification in food and preconception folic acid consumption are cost-effective ways to reduce the incidence and prevalence of NTDs. This review highlights the significant cost burden that NTDs pose to healthcare systems, various healthcare payers, and society and concludes that the benefits of prevention of NTDs with folic acid far outweigh the cost. Further intervention with folic acid is justified in countries where the full potential of folic acid to reduce the risk of NTDs has not been realized.

  19. Sensitivity of Saccharomyces cerevisiae defective in TOR signaling pathway to carbonyl/oxidative stress

    Directory of Open Access Journals (Sweden)

    Valishkevych B. V.

    2014-09-01

    Full Text Available Aim. To investigate the influence of carbonyl/oxidative stress induced by glyoxal, methylglyoxal and hydrogen peroxide on the survival of Saccharomyces cerevisiae, defective for different parts of TOR- signaling pathway, grown on glucose or fructose. Methods. The assessment of number of colony-forming units to determine the yeast reproductive ability. Results. It was shown that at certain concentrations the mentioned above toxicants caused an increase in yeast survival, indicating the hormetic effect. Conclusions. The TOR signaling pathway is involved in the hormetic effect, but it is specific for each strain and depends on the type of carbohydrate in the incubation medium.

  20. Hypotrophy of conduit artery walls of the offspring of nitric oxide-defective rats

    OpenAIRE

    Kristek F.; Gerová M.

    2004-01-01

    The objective of the present study was to investigate the structure of the arterial walls of the offspring stemming from nitric oxide (NO)-defective hypertensive parents. The parents were treated with N G-nitro-L-arginine methyl ester (40 mg kg-1 day-1) for 5 weeks. Blood pressure was measured noninvasively in six 30-day-old rats and nine age-matched controls. The cardiovascular system was perfused with glutaraldehyde at 120 mmHg. The thoracic aorta and carotid artery were processed for elect...

  1. Polyaniline: Aniline oxidation with strong and weak oxidants under various acidity

    Energy Technology Data Exchange (ETDEWEB)

    Bláha, Michal, E-mail: blaha@imc.cas.cz [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, 162 06 Prague 6 (Czech Republic); Trchová, Miroslava; Bober, Patrycja; Morávková, Zuzana [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, 162 06 Prague 6 (Czech Republic); Prokeš, Jan [Charles University, Faculty of Mathematics and Physics, 180 00 Prague 8 (Czech Republic); Stejskal, Jaroslav [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, 162 06 Prague 6 (Czech Republic)

    2017-06-15

    Aniline was oxidized with three strong inorganic oxidants (ammonium peroxydisulfate, cerium(IV) sulfate, potassium dichromate), two weak inorganic oxidants (iron(III) chloride, silver nitrate), and one organic oxidant (p-benzoquinone) in aqueous solutions of methanesulfonic acid (MSA) of various concentration. Whereas oxidation of aniline with ammonium peroxydisulfate yielded high-molecular-weight conducting polyaniline (PANI) in the whole acidity range, the oxidation with cerium(IV) sulfate led also to a single product close to PANI with considerably lower molecular weight and lower conductivity. Potassium dichromate gave PANI only at high concentration of MSA. The use of iron(III) chloride yielded composite mixtures of PANI and low-molecular-weight aniline oligomers. The oxidation of aniline with silver nitrate led to composites of silver and an organic part, which was constituted either by aniline oligomers or conducting polyaniline or both. p-Benzoquinone as oxidant produced mainly aniline oligomers with poor conductivity and 2,5-dianilino-p-benzoquinone-like structure detected in FTIR and Raman spectra when oxidation proceeded with weak oxidants. A general model of oxidation with strong and weak oxidants was formulated. - Highlights: • Comparison of aniline oxidation with oxidants of different redox potential. • UV–vis, FTIR and Raman spectroscopies combined with size-exclusion chromatography. • The contents of polymer and oligomers were analyzed and discussed. • General model of aniline oxidation with strong and weak oxidants was formulated.

  2. Puerto Rican primary physicians' knowledge about folic acid supplementation for the prevention of neural tube defects.

    Science.gov (United States)

    Miranda, Ana; Dávila Torres, René R; Gorrín Peralta, José J; Montes de Longo, Idalina

    2003-12-01

    We conducted a study of a group of primary physicians in Puerto Rico to evaluate their knowledge about folic acid supplementation to prevent neural tube defects. The study design was transverse-correlational. A total of 66 primary physicians in two hospitals (public and private) participated in the study. The sample was nonrandom and opportunistic, and only those physicians present in the hospitals at the moment of distribution of the questionnaires participated. A self-administered and anonymous questionnaire was used. Descriptive statistics and cross-tabular analysis were used to describe the results of this study. Inferential statistics were also used, including Chi square and t-tests to establish the associations/differences between physician knowledge and the independent variables. Of the participants, 87.9% demonstrated an inadequate knowledge about folic acid supplementation for the prevention of neural tube defects as part of preconception care and only 12.1% demonstrated adequate knowledge. Older physicians had greater knowledge about folic acid. Also, women demonstrated greater knowledge about folic acid than did men. Most of the physicians who always recommend supplementation to their patients demonstrated a greater knowledge about folic acid, and all participants with adequate knowledge came from the public hospital. Despite a concerted effort by the Health Department of Puerto Rico to provide education in the importance of folic acid supplementation to reduce the incidence of neural tube defects, primary physicians in two Puerto Rican hospitals generally have not availed themselves of this training and showed a lack of knowledge on this important clinical issue. Copyright 2003 Wiley-Liss, Inc.

  3. Macrokinetics of magnesium sulfite oxidation inhibited by ascorbic acid

    Energy Technology Data Exchange (ETDEWEB)

    Lidong, Wang, E-mail: wld@tsinghua.edu.cn [School of Environmental Science and Engineering, North China Electric Power University, Baoding 071003 (China); Department of Environmental Science and Engineering, Tsinghua University, Beijing 100054 (China); Yongliang, Ma, E-mail: liang@tsinghua.edu.cn [Department of Environmental Science and Engineering, Tsinghua University, Beijing 100054 (China); Wendi, Zhang; Qiangwei, Li; Yi, Zhao [School of Environmental Science and Engineering, North China Electric Power University, Baoding 071003 (China); Zhanchao, Zhang [Jinan Environmental Monitoring Center, Jinan 250014 (China)

    2013-08-15

    Graphical abstract: Ascorbic acid is used as an inhibitor to retard the oxidation rate of magnesium sulfite. It shows that the oxidation rate would decrease greatly with the rise of initial ascorbic acid concentration, which provides a useful reference for sulfite recovery in magnesia desulfurization. -- Highlights: • We studied the kinetics of magnesium sulfite oxidation inhibited by ascorbic acid. • The oxidation process was simulated by a three-phase model and proved by HPLC–MS. • We calculated the kinetic parameters of intrinsic oxidation of magnesium sulfite. -- Abstract: Magnesia flue gas desulfurization is a promising process for small to medium scale industrial coal-fired boilers in order to reduce sulfur dioxide emissions, in which oxidation control of magnesium sulfite is of great importance for the recycling of products. Effects of four inhibitors were compared by kinetic experiments indicating that ascorbic acid is the best additive, which retards the oxidation process of magnesium sulfite in trace presence. The macrokinetics of magnesium sulfite oxidation inhibited by ascorbic acid were studied. Effects of the factors, including ascorbic acid concentration, magnesium sulfite concentration, oxygen partial pressure, pH, and temperature, were investigated in a stirred reactor with bubbling. The results show that the reaction rate is −0.55 order in ascorbic acid, 0.77 in oxygen partial pressure, and zero in magnesium sulfite concentration, respectively. The apparent activation energy is 88.0 kJ mol{sup −1}. Integrated with the kinetic model, it is concluded that the oxidation rate of magnesium sulfite inhibited by ascorbic acid is controlled by the intrinsic chemical reaction. The result provides a useful reference for sulfite recovery in magnesia desulfurization.

  4. Circumvention of defective neutral amino acid transport in Hartnup disease using tryptophan ethyl ester.

    Science.gov (United States)

    Jonas, A J; Butler, I J

    1989-07-01

    Tryptophan ethyl ester, a lipid-soluble tryptophan derivative, was used to bypass defective gastrointestinal neutral amino acid transport in a child with Hartnup disease. The child's baseline tryptophan concentrations in serum (20 +/- 6 microM) and cerebrospinal fluid (1.0 +/- 0.2 microM) were persistently less than 50% of normal values. Cerebrospinal fluid 5-hydroxyindoleacetic acid (5-HIAA), a serotonin metabolite, was also less than 50% of normal (21 +/- 2 ng/ml). Serum tryptophan concentrations increased only modestly and briefly after an oral challenge with 200 mg/kg of oral L-tryptophan, reflecting the absorptive defect. An oral challenge with 200 mg/kg of tryptophan ethyl ester resulted in a prompt increase in serum tryptophan to a peak of 555 microM. Sustained treatment with 20 mg/kg q6h resulted in normalization of serum (66 +/- 15 microM) and cerebrospinal fluid tryptophan concentrations (mean = 2.3 microM). Cerebrospinal fluid 5-HIAA increased to more normal concentrations (mean = 33 ng/ml). No toxicity was observed over an 8-mo period of treatment, chronic diarrhea resolved, and body weight, which had remained unchanged for 7 mo before ester therapy, increased by approximately 26%. We concluded that tryptophan ethyl ester is effective at circumventing defective gastrointestinal neutral amino acid transport and may be useful in the treatment of Hartnup disease.

  5. Folic acid supplement use in the prevention of neural tube defects.

    Science.gov (United States)

    Delany, C; McDonnell, R; Robson, M; Corcoran, S; Fitzpatrick, C; De La Harpe, D

    2011-01-01

    In 2008, planned folic acid fortification for the prevention of Neural Tube Defects (NTD) was postponed. Concurrently, the economic recession may have affected dietary folic acid intake, placing increased emphasis on supplement use. This study examined folic acid supplement use in 2009. A cross-sectional survey of 300 ante-natal women was undertaken to assess folic acid knowledge and use. Associations between demographic, obstetric variables and folic acid knowledge and use were examined. A majority, 284/297 (96%), had heard of folic acid, and 178/297 (60%) knew that it could prevent NTD. Most, 270/297 (91%) had taken it during their pregnancy, but only 107/297 (36%) had used it periconceptionally. Being older, married, planned pregnancy and better socioeconomic status were associated with periconceptional use. Periconceptional folic acid use in 2009 was very low, little changed from economic status were associated with periconceptional use. Periconceptional folic acid use in 2009 was very low, little changed from earlier years. Continuous promotion efforts are necessary. Close monitoring of folic acid intake and NTD rates is essential, particularly in the absence of fortification.

  6. Folic acid for the prevention of neural tube defects: the Danish experience.

    Science.gov (United States)

    Olsen, Sjurdur F; Knudsen, Vibeke Kildegaard

    2008-06-01

    Evidence from controlled trials suggests that ingestion of 0.4 mg of folic acid per day in the periconceptional period is effective in preventing neural tube defects (NTD). For this reason, most countries recommend that women planning pregnancy take folic acid supplements in the periconceptional period, and some countries even fortify stable foods with folic acid. Denmark exemplifies a country with a relatively conservative attitude with respect to taking action in these matters. In 1999, a national information campaign was launched that recommended women planning pregnancy take 0.4 mg of folic acid periconceptionally, but with the moderation that women who eat a healthy diet do not need to take folic acid supplement. The campaign was repeated during 2001. The results of the latter campaign were evaluated by using data from a national survey among pregnant women conducted simultaneously with the campaign by the Danish National Birth Cohort. An increase in the proportion of folic acid users took place concomitantly with the launching of the information events, but the increase was limited. Among women who did not plan their pregnancy, a small proportion had taken folic acid supplements periconceptionally, and this proportion did not change concomitantly with the campaign. Young age and low education were factors associated with low likelihood of taking folic acid. It seems that different and more efficient actions are needed if a more substantial proportion of Danish women and their fetuses are going to benefit from the knowledge that folic acid supplementation in the periconceptional period can prevent NTD.

  7. Folic acid supplement use in the prevention of neural tube defects.

    LENUS (Irish Health Repository)

    Delany, C

    2011-01-01

    In 2008, planned folic acid fortification for the prevention of Neural Tube Defects (NTD) was postponed. Concurrently, the economic recession may have affected dietary folic acid intake, placing increased emphasis on supplement use. This study examined folic acid supplement use in 2009. A cross-sectional survey of 300 ante-natal women was undertaken to assess folic acid knowledge and use. Associations between demographic, obstetric variables and folic acid knowledge and use were examined. A majority, 284\\/297 (96%), had heard of folic acid, and 178\\/297 (60%) knew that it could prevent NTD. Most, 270\\/297 (91%) had taken it during their pregnancy, but only 107\\/297 (36%) had used it periconceptionally. Being older, married, planned pregnancy and better socioeconomic status were associated with periconceptional use. Periconceptional folic acid use in 2009 was very low, little changed from economic status were associated with periconceptional use. Periconceptional folic acid use in 2009 was very low, little changed from earlier years. Continuous promotion efforts are necessary. Close monitoring of folic acid intake and NTD rates is essential, particularly in the absence of fortification.

  8. Oxidation of Alpha-Ketoglutarate Is Required for Reductive Carboxylation in Cancer Cells with Mitochondrial Defects

    Directory of Open Access Journals (Sweden)

    Andrew R. Mullen

    2014-06-01

    Full Text Available Mammalian cells generate citrate by decarboxylating pyruvate in the mitochondria to supply the tricarboxylic acid (TCA cycle. In contrast, hypoxia and other impairments of mitochondrial function induce an alternative pathway that produces citrate by reductively carboxylating α-ketoglutarate (AKG via NADPH-dependent isocitrate dehydrogenase (IDH. It is unknown how cells generate reducing equivalents necessary to supply reductive carboxylation in the setting of mitochondrial impairment. Here, we identified shared metabolic features in cells using reductive carboxylation. Paradoxically, reductive carboxylation was accompanied by concomitant AKG oxidation in the TCA cycle. Inhibiting AKG oxidation decreased reducing equivalent availability and suppressed reductive carboxylation. Interrupting transfer of reducing equivalents from NADH to NADPH by nicotinamide nucleotide transhydrogenase increased NADH abundance and decreased NADPH abundance while suppressing reductive carboxylation. The data demonstrate that reductive carboxylation requires bidirectional AKG metabolism along oxidative and reductive pathways, with the oxidative pathway producing reducing equivalents used to operate IDH in reverse.

  9. Targets for modulation of fatty acid oxidation in the heart.

    Science.gov (United States)

    Lopaschuk, Gary D

    2004-03-01

    Fatty acids are a major source of fuel used by the heart to provide large amounts of energy necessary to sustain contractile function. In the healthy heart, a balance between fatty acid and carbohydrate use ensures that energy supply to the heart matches demand. However, myocardial ischemia causes profound changes in metabolism, including alterations in glucose and fatty acid metabolism that can lead to excessive myocardial fatty acid oxidation, which occurs at the expense of glucose oxidation. This contributes to cellular acidosis, a decrease in cardiac efficiency and contractile dysfunction in the ischemic heart. Inhibition of fatty acid oxidation has recently emerged as a promising approach to the prevention of these adverse effects of fatty acids. As a result, a number of key enzymes involved in the metabolism of fatty acids are potential targets for therapeutic intervention in myocardial ischemia. This includes inhibition of fatty acid uptake into the myocyte, inhibition of mitochondrial fatty acid uptake and direct inhibition of fatty acid beta-oxidation. This review describes these potential targets for modulation of energy metabolism in the heart.

  10. Investigation of defects in In–Ga–Zn oxide thin film using electron spin resonance signals

    Energy Technology Data Exchange (ETDEWEB)

    Nonaka, Yusuke; Kurosawa, Yoichi; Komatsu, Yoshihiro; Ishihara, Noritaka; Oota, Masashi; Nakashima, Motoki; Hirohashi, Takuya; Takahashi, Masahiro; Yamazaki, Shunpei [Semiconductor Energy Laboratory Co., Ltd., 398 Hase, Atsugi, Kanagawa 243-0036 (Japan); Obonai, Toshimitsu; Hosaka, Yasuharu; Koezuka, Junichi [Advanced Film Device, Inc., 161-2 Masuzuka, Tsuga-machi, Tochigi, Tochigi 328-0114 (Japan); Yamauchi, Jun [Semiconductor Energy Laboratory Co., Ltd., 398 Hase, Atsugi, Kanagawa 243-0036 (Japan); Emeritus Professor of Kyoto University, Oiwake-cho, Kitashirakawa, Kyoto 606-8502 (Japan)

    2014-04-28

    In–Ga–Zn oxide (IGZO) is a next-generation semiconductor material seen as an alternative to silicon. Despite the importance of the controllability of characteristics and the reliability of devices, defects in IGZO have not been fully understood. We investigated defects in IGZO thin films using electron spin resonance (ESR) spectroscopy. In as-sputtered IGZO thin films, we observed an ESR signal which had a g-value of g = 2.010, and the signal was found to disappear under thermal treatment. Annealing in a reductive atmosphere, such as N{sub 2} atmosphere, generated an ESR signal with g = 1.932 in IGZO thin films. The temperature dependence of the latter signal suggests that the signal is induced by delocalized unpaired electrons (i.e., conduction electrons). In fact, a comparison between the conductivity and ESR signal intensity revealed that the signal's intensity is related to the number of conduction electrons in the IGZO thin film. The signal's intensity did not increase with oxygen vacancy alone but also with increases in both oxygen vacancy and hydrogen concentration. In addition, first-principle calculation suggests that the conduction electrons in IGZO may be generated by defects that occur when hydrogen atoms are inserted into oxygen vacancies.

  11. The influence of chemisorption on the defect equilibrium of metal oxide thin films

    Science.gov (United States)

    Geistlinger, H.

    1996-08-01

    Using the exact charge density of intrinsic point defects of metal oxides (MOs), the phenomenological electron theory of chemisorption, developed by Volkenstein, is applied to acceptorlike and donorlike chemisorption on MO thin films for the whole ξ region (where ξ=D/LD, D is the film thickness, and LD is Debye length). The experimental temperature and oxygen partial pressure dependence of the averaged electron concentration (pO2,T)∝e-EA/kTpO2-m(T) for polycrystalline ZnO films are discussed on the bases of three different models: the Schottky-defect model, the Volkenstein model for electronic equilibrium, and the comprehensive model for complete equilibrium. It turns out that a Schottky-defect model that uses single-crystal-mass action constants will not yield the experimental high temperature limit (T=1000 K: EA=1.6 eV, m=0.26). This limit is obtained using a higher averaged concentration of oxygen vacancies for polycrystalline films (due to the presence of grain boundaries). The comparison between the electronic and complete equilibrium shows that the screening of the surface charge through mobile positively charged oxygen vacancies has a tremendous reducing effect of about 30% of the surface potential in the temperature range considered.

  12. Charged defects during alpha-irradiation of actinide oxides as revealed by Raman and luminescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Mohun, R.; Desgranges, L.; Léchelle, J. [CEA/DEN/DEC/SESC, Centre de Cadarache, 13108 Saint-Paul-lez-Durance (France); Simon, P.; Guimbretière, G.; Canizarès, A.; Duval, F. [CNRS, UPR 3079 CEMHTI, et Université d’Orléans, 1D avenue de la Recherche Scientifique, 45071 Orléans (France); Jegou, C.; Magnin, M. [CEA/DEN/DTCD, Centre de Marcoule, BP 17171, 30207 Bagnols sur Cèze (France); Clavier, N.; Dacheux, N. [ICSM, UMR 5257 CEA/CNRS/UM2/ENSCM, Site de Marcoule, BP 17171, 30207 Bagnols sur Cèze (France); Valot, C. [CEA/DEN/DTEC/SECA/LCC, BP 17171, 30207 Bagnols sur Cèze (France); Vauchy, R. [CEA/DEN/DEC/SPUA, Centre de Cadarache, 13108 Saint-Paul-lez-Durance (France)

    2016-05-01

    We have recently evidenced an original Raman signature of alpha irradiation-induced defects in UO{sub 2}. In this study, we aim to determine whether the same signature also exists in different actinide oxides, namely ThO{sub 2} and PuO{sub 2}. Sintered UO{sub 2} and ThO{sub 2} were initially irradiated with 21 MeV He{sup 2+} ions using a cyclotron device and were subjected to an in situ luminescence experiment followed by Raman analysis. In addition, a PuO{sub 2} sample which had accumulated self-irradiation damage due to alpha particles was investigated only by Raman measurement. Results obtained for the initially white ThO{sub 2} showed that a blue color appeared in the irradiated areas as well as luminescence signals during irradiation. However, Raman spectroscopic analysis showed the absence of Raman signature in ThO{sub 2}. In contrast, the irradiated UO{sub 2} and PuO{sub 2} confirmed the presence of the Raman signature but no luminescence peaks were observed. The proposed mechanism involves electronic defects in ThO{sub 2}, while a coupling between electronic defects and phonons is required to explain the Raman spectra for UO{sub 2} and PuO{sub 2}.

  13. Formic acid oxidation at platinum-bismuth catalysts

    National Research Council Canada - National Science Library

    Popović Ksenija Đ; Lović Jelena D

    2015-01-01

    ..., activity, and stability. The oxidation of formic acid is of permanent interest as a model reaction for the mechanistic understanding of the electrooxidation of small organic molecules and because of its technical relevance...

  14. Sodium Picosulfate, Magnesium Oxide, and Anhydrous Citric Acid

    Science.gov (United States)

    Sodium picosulfate, magnesium oxide, and anhydrous citric acid combination powder is used to empty the colon (large ... clear view of the walls of the colon. Sodium picosulfate is in a class of medications called ...

  15. AMPK-independent pathways regulate skeletal muscle fatty acid oxidation

    DEFF Research Database (Denmark)

    Dzamko, Nicolas; Schertzer, Jonathan D.; Ryall, James G.

    2008-01-01

    , malonyl-CoA levels were reduced and rates of fatty acid oxidation were comparable between genotypes. During treadmill exercise both KD and WT mice had similar values of respiratory exchange ratio. These studies suggested the presence of an alternative ACC2 kinase(s). Using a phosphoproteomics......The activation of AMP-activated protein kinase (AMPK) and phosphorylation/inhibition of acetyl-CoA carboxylase 2 (ACC2) is believed to be the principal pathway regulating fatty acid oxidation. However, during exercise AMPK activity and ACC Ser-221 phosphorylation does not always correlate...... with rates of fatty acid oxidation. To address this issue we have investigated the requirement for skeletal muscle AMPK in controlling aminoimidazole-4-carboxymide-1-beta-d-ribofuranoside (AICAR) and contraction-stimulated fatty acid oxidation utilizing transgenic mice expressing a muscle-specific kinase...

  16. The enzymology of mitochondrial fatty acid beta-oxidation and its application to follow-up analysis of positive neonatal screening results.

    Science.gov (United States)

    Wanders, Ronald J A; Ruiter, Jos P N; IJLst, Lodewijk; Waterham, Hans R; Houten, Sander M

    2010-10-01

    Oxidation of fatty acids in mitochondria is a key physiological process in higher eukaryotes including humans. The importance of the mitochondrial beta-oxidation system in humans is exemplified by the existence of a group of genetic diseases in man caused by an impairment in the mitochondrial oxidation of fatty acids. Identification of patients with a defect in mitochondrial beta-oxidation has long remained notoriously difficult, but the introduction of tandem-mass spectrometry in laboratories for genetic metabolic diseases has revolutionalized the field by allowing the rapid and sensitive analysis of acylcarnitines. Equally important is that much progress has been made with respect to the development of specific enzyme assays to identify the enzyme defect in patients subsequently followed by genetic analysis. In this review, we will describe the current state of knowledge in the field of fatty acid oxidation enzymology and its application to the follow-up analysis of positive neonatal screening results.

  17. The use of folic acid for the prevention of neural tube defects and other congenital anomalies.

    Science.gov (United States)

    Wilson, R Douglas; Davies, Gregory; Désilets, Valérie; Reid, Gregory J; Summers, Anne; Wyatt, Philip; Young, David

    2003-11-01

    To provide information regarding the use of folic acid for the prevention of neural tube defects (NTDs) and other congenital anomalies, in order that physicians, midwives, nurses, and other health-care workers can assist in the education of women in the preconception phase of their health care. OPTION: Folic acid supplementation is problematic, since 50% of pregnancies are unplanned and the health status of women may not be optimal. Folic acid supplementation has been proven to decrease or minimize specific birth defects. A systematic review of the literature, including review and peer-reviewed articles, government publications, the previous Society of Obstetricians and Gynaecologists of Canada (SOGC) Policy Statement of March 1993, and statements from the American College of Obstetrics and Gynecology, was used to develop a new clinical practice guideline for the SOGC. Peer-review process within the committee structure. The benefit is reduced lethal and severe morbidity birth defects and the harm is minimal. The personal cost is of vitamin supplementation on a daily basis and eating a healthy diet. 1. Women in the reproductive age group should be advised about the benefits of folic acid supplementation during wellness visits (birth control renewal, Pap testing, yearly examination), especially if pregnancy is contemplated. (III-A) 2. Women should be advised to maintain a healthy nutritional diet, as recommended in Canada's Food Guide to Healthy Eating (good or excellent sources of folic acid: broccoli, spinach, peas, Brussels sprouts, corn, beans, lentils, oranges). (III-A) 3. Women who could become pregnant should be advised to take a multivitamin containing 0.4 mg to 1.0 mg of folic acid daily. (II-1A) 4. Women taking a multivitamin with folic acid supplement should be advised not to take more than 1 daily dose of vitamin supplement, as indicated on the product label. (II-2A) 5. Women in intermediate- to high-risk categories for NTDs (NTD-affected previous

  18. Folic acid supplements to prevent neural tube defects: trends in East of Ireland 1996-2002.

    Science.gov (United States)

    Ward, M; Hutton, J; Mc Donnell, R; Bachir, N; Scallan, E; O'Leary, M; Hoey, J; Doyle, A; Delany, V; Sayers, G

    2004-10-01

    Promotion of folic acid to prevent neural Tube Defects (NTD) has been ongoing for ten years in Ireland, without a concomitant reduction in the total birth prevalence of NTD. The effectiveness of folic acid promotion as the sole means of primary prevention of NTD is therefore questionable. We examined trends in folic acid knowledge and peri-conceptional use from 1996-2002 with the aim of assessing the value of this approach. From 1996-2002, 300 women attending ante-natal clinics in Dublin hospitals annually were surveyed regarding their knowledge and use of folic acid. During the period the proportion who had heard of folic acid rose from 54% to 94% between 1996 and 2002 (c2 test for trend: pfolic acid can prevent NTD also rose from 21% to 66% (c2 test for trend: pfolic acid during pregnancy increased from 14% to 83% from 1996 to 2002 (c2 test for trend: pawareness of folic acid and its relation to NTD, which is not matched by peri-conceptional uptake. The main barrier to peri-conceptional uptake is the lack of pregnancy planning. To date promotional campaigns appear to have been ineffective in reducing the prevalence of NTD in Ireland. Consequently, fortification of staple foodstuffs is the only practical and reliable means of primary prevention of NTD.

  19. Induction of omega-oxidation of monocarboxylic acids in rats by acetylsalicylic acid.

    Science.gov (United States)

    Kundu, R K; Tonsgard, J H; Getz, G S

    1991-12-01

    The accumulation of dicarboxylic acids, particularly long chain, is a prominent feature of Reye's syndrome and diseases of peroxisomal metabolism. We assessed the omega-oxidation of a spectrum of fatty acids in rats and asked whether pretreatment of rats with aspirin, which is known to predispose children to Reye's syndrome, would affect omega-oxidation of long chain fatty acids. We found that aspirin increased liver free fatty acids and increased the capacity for omega-oxidation three- to sevenfold. Omega-oxidation of long chain substrate was stimulated to a greater degree than medium chain substrate and was apparent within one day of treatment, at serum aspirin concentrations below the therapeutic range in humans. The apparent Km for lauric acid was 0.9 microM and 12 microM for palmitate. We also found a difference in the storage stability of activity toward medium and long chain substrate. Saturating concentrations of palmitate had no effect on the formation of dodecanedioic acid, whereas laurate decreased but never eliminated the omega-oxidation of palmitate. 97% of the total laurate omega-oxidative activity recovered was found in the microsomes, but 32% of palmitate omega-oxidative activity was present in the cytosol. These results demonstrate that aspirin is a potent stimulator of omega-oxidation and suggest that there may be multiple enzymes for omega-oxidation with overlapping substrate specificity.

  20. Prevention of neural tube defects by folic acid - awareness among women of childbearing age in Slovakia.

    Science.gov (United States)

    Horn, F; Sabova, L; Pinterova, E; Hornova, J; Trnka, J

    2014-01-01

    Folic acid deficiency plays a central role in the aetiology of many congenital anomalies including neural tube defects. Protective effect of folic acid on embryo may be acquired only if taken periconceptionally. The aim of the study was to investigate the awareness about folic acid among women of childbearing age in Bratislava, Slovakia. There were 130 respondents involved in the research (106 pregnant women, 24 female students of medical faculty). Using questionnaire we acquired following data: pregnancy details, interest in diet before and during pregnancy, recommendations regarding nutrition and supplementation pre- and post-conception, knowledge about folic and other acid in 2004 and 2009. More than half of the respondents knew the sources of folic acid. The interest in the nutrition facts of the food dropped from 91 % to 58.5 %. The number of pregnant women advised about correct nutrition and folic acid supplementation before and during pregnancy increased from 16 % to 37 %. Planning the next gravidity with folic acid supplementation became greater than 21 % (38 % in 2009). Nevertheless, only 46 % of these women believed that proper food content with folic acid may prevent congenital anomalies. In a group of students planning to take folic acid periconceptionally the number raised up to 62.5 %. The results revealed low knowledge about the effect of folic acid on developing embryo among women of childbearing age. Effective intervention programs are needed with the aim to improve periconceptional intake of folic acid in 2004 and 2009. The results in both periods show low knowledge about this essential vitamin (Tab. 1, Fig. 8, Ref. 31).

  1. The Oxidation of Hydrazine by Nitric Acid

    Energy Technology Data Exchange (ETDEWEB)

    Karraker, D.G.

    2001-07-02

    Hydrazine nitrate-nitric acid solutions are used in the ion exchange process for separating Pu-238 and Np-237 and have been found to dissolve plutonium metal in a manner advantageous to SRP metal recovery operations. Laboratory tests on the stability of hydrazine in nitric acid solutions were performed to obtain accurate data, and the results of these tests are reported here. These tests provide sufficient information to specify temperature control for hydrazine-nitric acid solutions in plant processes.

  2. Platinum nanoparticles–manganese oxide nanorods as novel binary catalysts for formic acid oxidation

    Directory of Open Access Journals (Sweden)

    Mohamed S. El-Deab

    2012-01-01

    Full Text Available The current study proposes a novel binary catalyst system (composed of metal/metal oxide nanoparticles as a promising electrocatalyst in formic acid oxidation. The electro-catalytic oxidation of formic acid is carried out with binary catalysts of Pt nanoparticles (nano-Pt and manganese oxide nanorods (nano-MnOx electrodeposited onto glassy carbon (GC electrodes. Cyclic voltammetric (CV measurements showed that unmodified GC and nano-MnOx/GC electrodes have no catalytic activity. While two oxidation peaks were observed at nano-Pt/GC electrode at ca. 0.2 and 0.55 V (corresponding to the direct oxidation of formic acid and the oxidation of the poisoning CO intermediate, respectively. The combined use of nano-MnOx and nano-Pt results in superb enhancement of the direct oxidation pathway. Nano-MnOx is shown to facilitate the oxidation of CO (to CO2 by providing oxygen at low over-potential. This leads to retrieval of Pt active sites necessary for the direct oxidation of formic acid. The higher catalytic activity of nano-MnOx/nano-Pt/GC electrode (with Pt firstly deposited compared to its mirror image electrode (i.e., with MnOx firstly deposited, nano-Pt/nano-MnOx/GC reveals that the order of the electrodeposition is an essential parameter.

  3. Assessment of Turkish women's knowledge concerning folic acid and prevention of birth defects.

    Science.gov (United States)

    Unusan, Nurhan

    2004-10-01

    In Turkey, the incidence of neural tube defects (NTDs) is 30.1 per 10,000 births. For this reason it seems an important problem for women of childbearing age. Adequate periconceptional consumption of folic acid could prevent NTDs. Most women are unaware of this recommendation. The objectives of this study were to evaluate women' knowledge and beliefs with regard to folic acid, and to estimate the consumption frequency of vitamin supplements periconceptionally and during the first trimester of pregnancy. Eight hundred and eighteen married women who had delivered a live-born infant within the previous 12 months completed the questionnaire. Each subject participated in a 20-minute interview, with the questionnaire comprising multiple-choice statements. A random sample of 10 public health centres was drawn from 27 in three districts in Konya where about 50% of the population lives. Only 22% of subjects had heard or read about folic acid. Thirteen per cent of women indicated knowledge of the direct link between folic acid supplementation and NTD prevention. The knowledge was greatest among 26- to 35-year-olds. Women with a university degree were more likely to have heard about folic acid than were less-educated women. The results indicate that further government efforts are needed to inform the population and promote the optimal use of folic acid supplements and folate-enriched foods. It is the responsibility of national authorities to increase health education concerning folic acid and the prevention of NTDs in their countries.

  4. Isoniazid cocrystals with anti-oxidant hydroxy benzoic acids

    Science.gov (United States)

    Mashhadi, Syed Muddassir Ali; Yunus, Uzma; Bhatti, Moazzam Hussain; Tahir, Muhammad Nawaz

    2014-11-01

    Isoniazid is the primary constituent of “triple therapy” used to effectively treat tuberculosis. In tuberculosis and other diseases, tissue inflammation and free radical burst from macrophages results in oxidative stress. These free radicals cause pulmonary inflammation if not countered by anti-oxidants. Therefore, in the present study cocrystals of isoniazid with four anti-oxidant hydroxy benzoic acids have been reported. Gallic acid, 2,3-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, and 3-hydroxybenzoic acid resulted in the formation of cocrystals when reacted with isoniazid. Cocrystal structure analysis confirmed the existence of pyridine-carboxylic acid synthon in the cocrystals of isoniazid with Gallic acid, 2,3-dihydroxybenzoic acid and 3-hydroxybenzoic acid. While cocrystal of 3,5-dihydroxybenzoic acid formed the pyridine-hydroxy group synthon. Other synthons of different graph sets are formed between hydrazide group of isoniazid and coformers involving Nsbnd H⋯O and Osbnd H⋯N bonds. All the cocrystals were in 1:1 stoichiometric ratio.

  5. Engineering the defect state and reducibility of ceria based nanoparticles for improved anti-oxidation performance

    Science.gov (United States)

    Wang, Yan-Jie; Dong, Hao; Lyu, Guang-Ming; Zhang, Huai-Yuan; Ke, Jun; Kang, Li-Qun; Teng, Jia-Li; Sun, Ling-Dong; Si, Rui; Zhang, Jing; Liu, Yan-Jun; Zhang, Ya-Wen; Huang, Yun-Hui; Yan, Chun-Hua

    2015-08-01

    Due to their excellent anti-oxidation performance, CeO2 nanoparticles receive wide attention in pharmacological application. Deep understanding of the anti-oxidation mechanism of CeO2 nanoparticles is extremely important to develop potent CeO2 nanomaterials for anti-oxidation application. Here, we report a detailed study on the anti-oxidation process of CeO2 nanoparticles. The valence state and coordination structure of Ce are characterized before and after the addition of H2O2 to understand the anti-oxidation mechanism of CeO2 nanoparticles. Adsorbed peroxide species are detected during the anti-oxidation process, which are responsible for the red-shifted UV-vis absorption spectra of CeO2 nanoparticles. Furthermore, the coordination number of Ce in the first coordination shell slightly increased after the addition of H2O2. On the basis of these experimental results, the reactivity of coordination sites for peroxide species is considered to play a key role in the anti-oxidation performance of CeO2 nanoparticles. Furthermore, we present a robust method to engineer the anti-oxidation performance of CeO2 nanoparticles through the modification of the defect state and reducibility by doping with Gd3+. Improved anti-oxidation performance is also observed in cell culture, where the biocompatible CeO2-based nanoparticles can protect INS-1 cells from oxidative stress induced by H2O2, suggesting the potential application of CeO2 nanoparticles in the treatment of diabetes.Due to their excellent anti-oxidation performance, CeO2 nanoparticles receive wide attention in pharmacological application. Deep understanding of the anti-oxidation mechanism of CeO2 nanoparticles is extremely important to develop potent CeO2 nanomaterials for anti-oxidation application. Here, we report a detailed study on the anti-oxidation process of CeO2 nanoparticles. The valence state and coordination structure of Ce are characterized before and after the addition of H2O2 to understand the anti-oxidation

  6. Photocatalytic Oxidation of Sulfurous Acid in an Aqueous Medium

    Science.gov (United States)

    Romero, Alicia; Hernandez, Willie; Suarez, Marco F.

    2005-01-01

    The effect of some parameters on sulfurous acid and sulfur oxidation kinetics such as initial concentration of sulfurous acid, oxygen, TiO[2] crystalline concentration, the power of black light, and quantity of TiO[2] is investigated. The experiments can be performed in an undergraduate physical chemistry laboratory with an inexpensive…

  7. Photocatalytic Oxidation of Sulfurous Acid in an Aqueous Medium

    Science.gov (United States)

    Romero, Alicia; Hernandez, Willie; Suarez, Marco F.

    2005-01-01

    The effect of some parameters on sulfurous acid and sulfur oxidation kinetics such as initial concentration of sulfurous acid, oxygen, TiO[2] crystalline concentration, the power of black light, and quantity of TiO[2] is investigated. The experiments can be performed in an undergraduate physical chemistry laboratory with an inexpensive…

  8. Control of food intake by fatty acid oxidation and ketogenesis.

    Science.gov (United States)

    Scharrer, E

    1999-09-01

    Fatty acid oxidation seems to provide an important stimulus for metabolic control of food intake, because various inhibitors of fatty acid oxidation (mercaptoacetate, methyl palmoxirate, R-3-amino-4-trimethylaminobutyric acid) stimulated feeding in rats and/or mice, in particular when fed a fat-enriched diet, and long-term intravascular infusion of lipids reduced voluntary food intake in various species, including humans. The feeding response to decreased fatty acid oxidation was due to a shortening of the intermeal interval with meal size remaining unaffected. Thus, energy derived from fatty acid oxidation seems to contribute to control of the duration of postmeal satiety and meal onset. Since inhibition of glucose metabolism by 2-deoxy-D-glucose affects feeding pattern similarly, and spontaneous meals were shown to be preceded by a transient decline in blood glucose in rats and humans, a decrease in energy availability from glucose and fatty acid oxidation seems to be instrumental in eliciting eating. Since the feeding response of rats to inhibition of fatty acid oxidation was abolished by total abdominal vagotomy and pretreatment with capsaicin destroying non-myelinated afferents and attenuated by hepatic branch vagotomy, fatty acid oxidation in abdominal tissues, especially in the liver, apparently is signalled to the brain by vagal afferents to affect eating. Brain lesions and Fos immunohistochemistry were employed to identify pathways within the brain mediating eating in response to decreased fatty acid oxidation. According to these studies, the nucleus tractus solitarii (NTS) of the medulla oblongata represents the gate for central processing of vagally mediated afferent information related to fatty acid oxidation. The lateral parabrachial nucleus of the pons seems to be a major relay for pertinent ascending input from the NTS. In particular the central nucleus of the amygdala, a projection area of the parabrachial nucleus, appears to be crucial for eating

  9. Genetic examination of initial amino acid oxidation and glutamate catabolism in the hyperthermophilic archaeon Thermococcus kodakarensis.

    Science.gov (United States)

    Yokooji, Yuusuke; Sato, Takaaki; Fujiwara, Shinsuke; Imanaka, Tadayuki; Atomi, Haruyuki

    2013-05-01

    Amino acid catabolism in Thermococcales is presumed to proceed via three steps: oxidative deamination of amino acids by glutamate dehydrogenase (GDH) or aminotransferases, oxidative decarboxylation by 2-oxoacid:ferredoxin oxidoreductases (KOR), and hydrolysis of acyl-coenzyme A (CoA) by ADP-forming acyl-CoA synthetases (ACS). Here, we performed a genetic examination of enzymes involved in Glu catabolism in Thermococcus kodakarensis. Examination of amino acid dehydrogenase activities in cell extracts of T. kodakarensis KUW1 (ΔpyrF ΔtrpE) revealed high NADP-dependent GDH activity, along with lower levels of NAD-dependent activity. NADP-dependent activities toward Gln/Ala/Val/Cys and an NAD-dependent threonine dehydrogenase activity were also detected. In KGDH1, a gene disruption strain of T. kodakarensis GDH (Tk-GDH), only threonine dehydrogenase activity was detected, indicating that all other activities were dependent on Tk-GDH. KGDH1 could not grow in a medium in which growth was dependent on amino acid catabolism, implying that Tk-GDH is the only enzyme that can discharge the electrons (to NADP(+)/NAD(+)) released from amino acids in their oxidation to 2-oxoacids. In a medium containing excess pyruvate, KGDH1 displayed normal growth, but higher degrees of amino acid catabolism were observed compared to those for KUW1, suggesting that Tk-GDH functions to suppress amino acid oxidation and plays an anabolic role under this condition. We further constructed disruption strains of 2-oxoglutarate:ferredoxin oxidoreductase and succinyl-CoA synthetase. The two strains displayed growth defects in both media compared to KUW1. Succinate generation was not observed in these strains, indicating that the two enzymes are solely responsible for Glu catabolism among the multiple KOR and ACS enzymes in T. kodakarensis.

  10. Assessment of student pharmacists' knowledge concerning folic acid and prevention of birth defects demonstrates a need for further education.

    Science.gov (United States)

    Lynch, Sean M

    2002-03-01

    Adequate periconceptional consumption of folic acid can prevent neural tube birth defects, and all women capable of becoming pregnant are recommended to consume 400 microg/d. Most women, however, are unaware of this recommendation and do not consume adequate amounts of folic acid. It is important, therefore, that healthcare professionals, such as pharmacists, be capable of educating women regarding folic acid. The aim of this study was to assess knowledge regarding prevention of birth defects by folic acid among student (future) pharmacists in the final year of a professional degree program. Over a 3-y period (1998-2000), students (n = 98) enrolled in a PharmD program completed a survey consisting of five multiple-choice questions concerning folic acid and birth defects. Almost all students (93.9%) correctly identified folic acid as preventing birth defects. Of these students, many also knew that supplementation should begin before pregnancy (73.9%). Fewer, however, were able to correctly identify either the recommended level of intake (55.4%) or good sources of folic acid (57.6-65.2%). These results show that although student (future) pharmacists are aware of folic acid's ability to prevent birth defects, many lack the specific knowledge needed to effectively counsel women in future clinical practice.

  11. [Folic acid and prevention of neural tube closure defects: the question is not solved yet].

    Science.gov (United States)

    Vidailhet, M; Bocquet, A; Bresson, J-L; Briend, A; Chouraqui, J-P; Dupont, C; Darmaun, D; Frelut, M-L; Ghisolfi, J; Girardet, J-P; Goulet, O; Putet, G; Rieu, D; Rigo, J; Turck, D

    2008-07-01

    Between 1981 and 1996, several interventional studies proved the efficacy of periconceptional folic acid supplementation in the prevention of neural tube closure defects (NTCD), first in women at risk (with a previous case of NTCD) and also in women of the general population in age to become pregnant. The poor observance of this supplementation led several countries (USA, Canada, Chile...) to decide mandatory folic acid fortification of cereals, which permitted a 30% (USA) to 46% (Canada) reduction in the incidence of NTCD. Moreover, this benefit was accompanied by a diminished incidence of several other malformations and of stroke and coronary accidents in elderly people. However, several papers drew attention to an increased risk of colorectal and breast cancer in relation with high blood folate levels and the use of folic acid supplements. A controlled interventional study showed a higher rate of recurrence of colic adenomas and a higher percentage of advanced adenomas in subjects receiving 1mg/day of folic acid. A recent study demonstrated an abrupt reversal of the downward trend in colorectal cancer 1 year after the beginning of cereal folic acid fortification in the USA and Canada. Two studies also reported impaired cognitive functions in elder persons with defective vitamin B(12) status. Taken in aggregate, these studies question the wisdom of a nationwide, mandatory, folic acid fortification of cereals. As of today, despite their limited preventive efficacy, a safe approach is to keep our current French recommendations and to increase the awareness of all caregivers, so as to improve the observance of these recommendations.

  12. Kinetics of Oxidation of 3-Benzoylpropionic Acid by N-Chlorobenzamide in Aqueous Acetic Acid Medium

    Directory of Open Access Journals (Sweden)

    N. A. Mohamed Farook

    2011-01-01

    Full Text Available The kinetics of oxidation of 3-benzoylpropionic acid (KA by N-chlorobenzamide (NCB in aqueous acetic acid medium in the presence of perchloric acid have been investigated. The observed rate of oxidation is first order dependence each in [KA], [NCB] and [H+]. The main product of the oxidation is the corresponding carboxylic acid. The rate decreases with the addition of benzamide, one of the products of the reaction. Variation in ionic strength of the reaction medium has no significant effect on the rate of oxidation. But the rate of the reaction is enhanced by lowering the dielectric constant of the reaction medium. Hypochlorous acidium ion (H2O+Cl, has been postulated as the reactive oxidizing species. A mechanism consistent with observed results have been proposed and the related rate law deduced. The activation parameters have been computed with respect to slow step of the mechanism.

  13. Candida cloacae oxidation of long-chain fatty acids to dioic acids.

    Science.gov (United States)

    Green; Turner; Woodley

    2000-08-01

    Candida cloacae cells oxidize long-chain fatty acids to their corresponding dicarboxylic acids (dioic acids) at rates dependent on their chain length and degree of saturation. This is despite the well-known toxicity of the fatty acids. Among the saturated substrates, the oxidation is limited to lauric acid (C12). The addition of pristane (5% v/v), which acts as an inert carrier for the poorly water-soluble substrate, boosts the oxidation of lauric acid to a rate that is comparable to that of dodecane. When dissolved in pristane, myristic (C14) and palmitic (C16) acids are effective carbon sources for C. cloacae, but dioic acid production is very low. Media glucose concentration and pH also influence cell growth and productivity. After the glucose is depleted, oxidation is optimal at a low pH. A two-phase (pristane/water) reaction was tested in a 2-l stirred tank bioreactor in which growth and oxidation were separated. A 50% w/w conversion of lauric acid (10 g/l) to dodecanedioic acid was achieved. The bioreactor also alleviated poor mass transfer characteristics experienced in shake flasks.

  14. HELLP Syndrome: Altered Hypoxic Response of the Fatty Acid Oxidation Regulator SIRT 4.

    Science.gov (United States)

    Sandvoß, Mareike; Potthast, Arne Björn; von Versen-Höynck, Frauke; Das, Anibh Martin

    2016-09-20

    The hemolysis, elevated liver enzymes, and low platelet count (HELLP) syndrome is frequently observed in mothers whose offspring have long-chain fatty acid oxidation defects. We previously found that fatty acid oxidation is compromised not only in these inborn errors of metabolism but also in human umbilical vein endothelial cells (HUVECs) from all pregnancies complicated by the HELLP syndrome. Sirtuins are oxidized nicotinamide adenine dinucleotide (NAD(+))dependent deacetylases linked to the metabolic status of the cell. SIRT 4 is known to have regulatory functions in fatty acid oxidation. The HELLP syndrome is often associated with short-term hypoxia. We studied sirtuins (SIRT 1, SIRT 3, and SIRT 4) in HUVECs from pregnancies complicated by the HELLP syndrome and uncomplicated pregnancies exposed to hypoxia (n = 7 controls, 7 HELLP; 0, 10, 60, or 120 minutes of 2% O2). Protein levels of SIRT 4 were significantly higher in HUVECs from HELLP compared to control after 60 and 120 minutes of hypoxia. The NAD(+) levels increased in a time-dependent manner.

  15. Gene expression in retinoic acid-induced neural tube defects A cDNA mieroarray analysis

    Institute of Scientific and Technical Information of China (English)

    Xiaodong Long; Zhong Yang; Yi Zeng; Hongli Li; Yangyun Han; Chao You

    2009-01-01

    BACKGROUND: Neural tube defects can be induced by abnormal factors in vivo or in vitro during development. However, the molecular mechanisms of neural tube defect induction, and the related gene expression and regulation are still unknown.OBJECTIVE: To compare the differences in gene expression between normal embryos and those with neural tube defects.DESIGN, TIME AND SETTING: A neural development study was performed at the Department of Neurobiology, Third Military Medical University of Chinese PLA between January 2006 and October 2007.MATERIALS: Among 120 adult Kunming mice, 60 pregnant mice were randomly and evenly divided into a retinoic acid group (n = 30) and a normal control group (n =30). The retinoic acid was produced by Sigma, USA, the gene microarray by the Amersham Pharmacia Company, Hong Kong, and the gene sequence was provided by the Incyte database, USA.METHODS: Retinoic acid was administered to prepare models of neural tube defects, and corn oil was similady administered to the normal control group. Total RNA was extracted from embryonic tissue of the two groups using a Trizol kit, and a cDNA microarray containing 1 100 known genes was used to compare differences in gene expression between the normal control group and the retinoic acid group on embryonic (E) clay 10.5 and 11.5. Several differentially expressed genes were randomly selected from the two groups for Northern blotting, to verify the results of the cDNA microarray.MAIN OUTCOME MEASURES: Morphological changes and differential gene expression between the normal control group and the retinoic acid group.RESULTS: Anatomical microscopy demonstrated that an intact closure of the brain was formed in the normal mouse embryos by days E10.5 and E11.5. The cerebral appearance was full and smooth, and the surface of the spine was intact. However, in the retinoic acid group on days E10.5 and E11.5, there were more dead embryos. Morphological malformations typically included non-closure at the top of

  16. The role of folic acid fortification in neural tube defects: a review.

    Science.gov (United States)

    Osterhues, Anja; Ali, Nyima S; Michels, Karin B

    2013-01-01

    The worldwide prevalence of neural tube defects (NTDs) has fallen noticeably during the past 30 years, but the specific etiology and causative mechanism of NTDs remain unknown. Since introduction of mandatory fortification of grains with folic acid, a further decrease in NTD prevalence has been reported in North America and other countries with large variations among ethnic subgroups. However, a significant portion of NTDs still persists. Population data suggest that women of childbearing age may not yet be adequately targeted, while the general population may be overfortified with folic acid. While an excessive folate intake may be associated with adverse effects, there remains uncertainty about the minimum effective folate intake and status required for NTD prevention, and the safe upper folate level. Besides folate, several other lifestyle and environmental factors as well as genetic variations may influence NTD development, possibly by affecting one-carbon metabolism and thus epigenetic events. In conclusion, mandatory folic acid fortification plays a significant part in the reduction of NTD prevalence, but possibly at a cost and with a portion of NTDs remaining. More effective preventive strategies require better understanding of the etiology of this group of birth defects.

  17. Role of folic acid supplementation in prevention of neural tube defects: physicians yet unaware!

    Science.gov (United States)

    Aggarwal, A; Kumhar, G Das; Harit, D; Faridi, M M A

    2010-09-01

    Folic acid supplementation is important in the prevention of Neural Tube Defects (NTD). The study was conducted to assess the awareness amongst physicians regarding the role of Folic Acid (FA) in the prevention of NTD. Physicians were interviewed regarding the awareness of FA dose, timing of supplementation and knowledge about its role in prevention of neural tube defects using a semistructured questionnaire. Among 202 physicians interviewed (48 pediatricians, 54 obstetricians, 100 recently qualified medical graduates) overall awareness about FA was present in 92.07%, similar in three groups (P > 0.05). Only 47.52% were aware of preconception administration, 61.38% about dose of supplementation and 11.88% about recurrence rate of NTD. Only 15 (7.4%) knew all these. Regarding the etiology of NTDs only 26.7% said both FA and genetic factors are involved. Though majority were aware that folic acid has a role in prevention of NTDs, their knowledge about timing and dose of supplementation was lacking. Hence attempts should be made to increase the awareness regarding prevention of NTD's by FA supplementation at a proper time.

  18. Kinetics of Oxidation of Some Amino Acids by N-Chlorosaccharin in Aqueous Acetic Acid Medium

    Directory of Open Access Journals (Sweden)

    N. A. Mohamed Farook

    2004-01-01

    Full Text Available The kinetics of oxidation of some amino acids namely, glycine, alanine, aspartic acid, arginine, and histidine, (AA by N-chlorosaccharin (NCSA in aqueous acetic acid medium in the presence of perchloric acid have been investigated. The observed rate of oxidation is first order in [AA], [NCSA] and of inverse fractional order in [H+]. The main product of the oxidation is the corresponding aldehyde. The ionic strength on the reaction rate has no significant effect. The effect of changing the dielectric constant of the medium on the rate indicates the reaction to be of dipole-dipole type. Hypochlorous acid has been postulated as the reactive oxidizing species. The reaction constants involved in the mechanism are derived. The activation parameters are computed with respect to slow step of the mechanism.

  19. Lack of periconceptional vitamins or supplements that contain folic acid and diabetes mellitus–associated birth defects

    Science.gov (United States)

    Correa, Adolfo; Gilboa, Suzanne M.; Botto, Lorenzo D.; Moore, Cynthia A.; Hobbs, Charlotte A.; Cleves, Mario A.; Riehle-Colarusso, Tiffany J.; Waller, D. Kim; Reece, E. Albert

    2016-01-01

    OBJECTIVE The purpose of this study was to examine the risk of birth defects in relation to diabetes mellitus and the lack of use of periconceptional vitamins or supplements that contain folic acid. STUDY DESIGN The National Birth Defects Prevention Study (1997-2004) is a multicenter, population-based case-control study of birth defects (14,721 cases and 5437 control infants). Cases were categorized into 18 types of heart defects and 26 noncardiac birth defects. We estimated odds ratios for independent and joint effects of preexisting diabetes mellitus and a lack of periconceptional use of vitamins or supplements that contain folic acid. RESULTS The pattern of odds ratios suggested an increased risk of defects that are associated with diabetes mellitus in the absence vs the presence of the periconceptional use of vitamins or supplements that contain folic acid. CONCLUSION The lack of periconceptional use of vitamins or supplements that contain folic acid may be associated with an excess risk for birth defects due to diabetes mellitus. PMID:22284962

  20. The comparison of gamma-radiation and electrical stress influences on oxide and interface defects in power VDMOSFET

    Directory of Open Access Journals (Sweden)

    Đorić-Veljković Snežana M.

    2013-01-01

    Full Text Available The behaviour of oxide and interface defects in n-channel power vertical double-diffused metal-oxide-semiconductor field-effect transistors, firstly degraded by the gamma-irradiation and electric field and subsequently recovered and annealed, is presented. By analyzing the transfer characteristic shifts, the changes of threshold voltage and underlying changes of gate oxide and interface trap densities during the stress (recovery, annealing of investigated devices, it is shown that these two types of stress influence differently on the gate oxide and the SiO2-Si interface. [Projekat Ministarstva nauke Republike Srbije, br. OI171026

  1. Chikusetsu saponin IVa regulates glucose uptake and fatty acid oxidation: implications in antihyperglycemic and hypolipidemic effects.

    Science.gov (United States)

    Li, Yuwen; Zhang, Tiejun; Cui, Jia; Jia, Na; Wu, Yin; Xi, Miaomiao; Wen, Aidong

    2015-07-01

    The aim of this study is to investigate antidiabetic effects and molecular mechanisms of the chemical Chikusetsu saponin IVa (CHS) that isolated from root bark of Aralia taibaiensis, which has multiple pharmacological activity, such as relieving rheumatism, promoting blood circulation to arrest pain and antidiabetic action. Rats with streptozotocin/nicotinamide-induced type 2 diabetes mellitus (T2DM) and insulin-resistant myocytes were used. Adenosine monophosphate (AMP)-activated protein kinase (AMPK) and acetyl-CoA carboxylase were quantified by immunoblotting. Assays of glucose uptake, fatty acid oxidation, glucose transporter 4 (GLUT4) translocation and carnitine palmitoyl transferase-1 (CPT-1) activity were performed. Chronic oral administration of CHS effectively decreases blood glucose, triglyceride, free fatty acid (FFA) and low density lipoprotein-cholesterol levels in T2DM rats. In both normal and insulin-resistant C2C12 myocytes, CHS activates AMPK, and increases glucose uptake or fatty acid oxidation through enhancing membrane translocation of GLUT4 or CPT-1 activity respectively. Knockdown of AMPK significantly diminishes the effects of CHS on glucose uptake and fatty acid oxidation. CHS is a novel AMPK activator that is capable of bypassing defective insulin signalling and could be useful for the treatment of T2DM or other metabolic disorders. © 2015 Royal Pharmaceutical Society.

  2. Obstructive heart defects associated with candidate genes, maternal obesity, and folic acid supplementation.

    Science.gov (United States)

    Tang, Xinyu; Cleves, Mario A; Nick, Todd G; Li, Ming; MacLeod, Stewart L; Erickson, Stephen W; Li, Jingyun; Shaw, Gary M; Mosley, Bridget S; Hobbs, Charlotte A

    2015-06-01

    Right-sided and left-sided obstructive heart defects (OHDs) are subtypes of congenital heart defects, in which the heart valves, arteries, or veins are abnormally narrow or blocked. Previous studies have suggested that the development of OHDs involved a complex interplay between genetic variants and maternal factors. Using the data from 569 OHD case families and 1,644 control families enrolled in the National Birth Defects Prevention Study (NBDPS) between 1997 and 2008, we conducted an analysis to investigate the genetic effects of 877 single nucleotide polymorphisms (SNPs) in 60 candidate genes for association with the risk of OHDs, and their interactions with maternal use of folic acid supplements, and pre-pregnancy obesity. Applying log-linear models based on the hybrid design, we identified a SNP in methylenetetrahydrofolate reductase (MTHFR) gene (C677T polymorphism) with a main genetic effect on the occurrence of OHDs. In addition, multiple SNPs in betaine-homocysteine methyltransferase (BHMT and BHMT2) were also identified to be associated with the occurrence of OHDs through significant main infant genetic effects and interaction effects with maternal use of folic acid supplements. We also identified multiple SNPs in glutamate-cysteine ligase, catalytic subunit (GCLC) and DNA (cytosine-5-)-methyltransferase 3 beta (DNMT3B) that were associated with elevated risk of OHDs among obese women. Our findings suggested that the risk of OHDs was closely related to a combined effect of variations in genes in the folate, homocysteine, or glutathione/transsulfuration pathways, maternal use of folic acid supplements and pre-pregnancy obesity. © 2015 Wiley Periodicals, Inc.

  3. Assembly of the oxidative phosphorylation system in humans: what we have learned by studying its defects.

    Science.gov (United States)

    Fernández-Vizarra, Erika; Tiranti, Valeria; Zeviani, Massimo

    2009-01-01

    Assembly of the oxidative phosphorylation (OXPHOS) system in the mitochondrial inner membrane is an intricate process in which many factors must interact. The OXPHOS system is composed of four respiratory chain complexes, which are responsible for electron transport and generation of the proton gradient in the mitochondrial intermembrane space, and of the ATP synthase that uses this proton gradient to produce ATP. Mitochondrial human disorders are caused by dysfunction of the OXPHOS system, and many of them are associated with altered assembly of one or more components of the OXPHOS system. The study of assembly defects in patients has been useful in unraveling and/or gaining a complete understanding of the processes by which these large multimeric complexes are formed. We review here current knowledge of the biogenesis of OXPHOS complexes based on investigation of the corresponding disorders.

  4. Awareness of folic acid for neural tube defect prevention among Israeli women.

    Science.gov (United States)

    Ringel, S; Lahat, E; Elizov, T; Greenberg, R; Arieli, S; Afriat, R; Berkovitch, M

    1999-07-01

    The failure of neural tube closure during early embryogenesis results in a range of neural tube defects (NTD), the most common of which is spina bifida. The role of folic acid in reducing the rate of NTD has been well-established. Three recent cases of infants with NTD inspired this investigative study into the level of awareness and knowledge of folic acid and its function in the prevention of NTD among Israeli women. Of 920 women interviewed, only 51 (5.5%) had heard of folic acid, and 27 (2.8%) were reported to have taken it. The source of information and the motivation for self-medication were also explored with regard to socioeconomic and health profile. Awareness of folic acid was significant among women aged 17-29 years (P = 0.005) and those aged 30-39 years (P = 0.009), and among semireligious and nonreligious women (P = 0.008 and 0.01, respectively). Among women who were aware of folic acid, only nonreligious women tended to take it. No correlation was found between folic acid intake and age, religiosity, nationality, number of pregnancies, and health status among women who were aware of folic acid intake. The poor level of awareness, evident in our study, demands that the medical community broadcast the benefit of folic acid. Furthermore, government health initiatives, such as the addition of folic acid to flour preparations, may effectively ensure its appropriate daily intake. These improved education and prevention programs may forcibly reduce the rate of NTD-affected pregnancies.

  5. Silicon surface and bulk defect passivation by low temperature PECVD oxides and nitrides

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Z.; Rohatgi, A. [Georgia Institute of Technology, Atlanta, GA (United States). Univ. Center of Excellence for Photovoltaics Research and Education; Ruby, D. [Sandia National Labs., Albuquerque, NM (United States)

    1995-01-01

    The effectiveness of PECVD passivation of surface and bulk defects in Si, as well as phosphorous diffused emitters, Is investigated and quantified. Significant hydrogen incorporation coupled with high positive charge density in the PECVD SiN layer is found to play an important role in bulk and surface passivation. It is shown that photo-assisted anneal in a forming gas ambient after PECVD depositions significantly improves the passivation of emitter and bulk defects. PECVD passivation of phosphorous doped emitters and boron doped bare Si surfaces is found to be a strong function of doping concentration. Surface recombination velocity of less than 200 cm/s for 0.2 Ohm-cm and less than 1 cm/s for high resistivity substrates ({approximately} Ohm-cm) were achieved. PECVD passivation improved bulk lifetime in the range of 30% to 70% in multicrystalline Si materials. However, the degree of the passivation was found to be highly material specific. Depending upon the passivation scheme, emitter saturation current density (J{sub oe}) can be reduced by a factor of 3 to 9. Finally, the stability of PECVD oxide/nitride passivation under prolonged UV exposure is established.

  6. Acid-free co-operative self-assembly of graphene-ZnO nanocomposites and its defect mediated visible light photocatalytic activities

    Science.gov (United States)

    Parameshwari, R.; Jothivenkatachalam, K.; Banks, Craig E.; Jeganathan, K.

    2017-02-01

    We propose an acid-free and environmental friendly surfactant based approach to anchor zinc oxide (ZnO) nanoparticles on graphene. Herein, liquid-phase exfoliated graphene in water by ultrasonic waves has been used to prepare graphene-ZnO (G-ZnO) nanocomposites that circumvent the use of various toxic acids and chemicals which are generally used in the preparation of graphene-based nanocomposites. Oxygen vacancy related defect peaks observed by Raman and photoluminescence confirm the formation of C-O-Zn bond due to the synergistic interaction of carbon and zinc via oxygen atoms in G-ZnO nanocomposites. The enhanced photocatalytic behavior of G-ZnO under visible light as evaluated using the dye Rhodamine B holds its genesis from the intrinsic oxygen defects in G-ZnO. Furthermore, graphene acts as electron sink for accumulation of charges from defect levels of ZnO, which controls recombination of charge carriers. It is envisaged that the acid-free and facile strategy can be a potential route for the preparation of graphene-based hybrid materials using liquid-phase exfoliation methodology.

  7. Acid-free co-operative self-assembly of graphene-ZnO nanocomposites and its defect mediated visible light photocatalytic activities

    Energy Technology Data Exchange (ETDEWEB)

    Parameshwari, R. [Centre for Nanoscience and Nanotechnology, School of Physics, Bharathidasan University, Tiruchirappalli 620024, Tamil Nadu (India); Jothivenkatachalam, K. [Department of Chemistry, Anna University, Tiruchirappalli 620024, Tamil Nadu (India); Banks, Craig E. [Faculty of Science and Engineering, Manchester Metropolitan University, Chester Street, Manchester M1 5GD (United Kingdom); Jeganathan, K., E-mail: kjeganathan@yahoo.com [Centre for Nanoscience and Nanotechnology, School of Physics, Bharathidasan University, Tiruchirappalli 620024, Tamil Nadu (India)

    2017-02-01

    We propose an acid-free and environmental friendly surfactant based approach to anchor zinc oxide (ZnO) nanoparticles on graphene. Herein, liquid-phase exfoliated graphene in water by ultrasonic waves has been used to prepare graphene-ZnO (G-ZnO) nanocomposites that circumvent the use of various toxic acids and chemicals which are generally used in the preparation of graphene-based nanocomposites. Oxygen vacancy related defect peaks observed by Raman and photoluminescence confirm the formation of C–O–Zn bond due to the synergistic interaction of carbon and zinc via oxygen atoms in G-ZnO nanocomposites. The enhanced photocatalytic behavior of G-ZnO under visible light as evaluated using the dye Rhodamine B holds its genesis from the intrinsic oxygen defects in G-ZnO. Furthermore, graphene acts as electron sink for accumulation of charges from defect levels of ZnO, which controls recombination of charge carriers. It is envisaged that the acid-free and facile strategy can be a potential route for the preparation of graphene-based hybrid materials using liquid-phase exfoliation methodology.

  8. Formic Acid Oxidation at Platinum-Bismuth Clusters

    DEFF Research Database (Denmark)

    Lovic, J. D.; Stevanovic, S. I.; Tripkovic, D. V.

    2014-01-01

    Formic acid oxidation was studied on platinum-bismuth deposits on glassy carbon (GC) substrate. The catalysts of equimolar ratio were prepared by potentiostatic deposition using chronocoulometry. Bimetallic structures obtained by two-step process, comprising deposition of Bi followed by deposition...... of Pt, were characterized by AFM spectroscopy which indicated that Pt crystallizes preferentially onto previously formed Bi particles. The issue of Bi leaching (dissolution) from PtBi catalysts, and their catalytic effect alongside the HCOOH oxidation is rather unresolved. In order to control Bi...... dissolution, deposits were subjected to electrochemical oxidation, in the relevant potential range and supporting electrolyte, prior to use as catalysts for HCOOH oxidation. Anodic striping charges indicated that along oxidation procedure most of deposited Bi was oxidized. ICP mass spectroscopy analysis...

  9. Automated Quantification of the Impact of Defects on the Mechanical Behavior of Deoxyribonucleic acid Origami Nanoplates.

    Science.gov (United States)

    Liang, Bowen; Nagarajan, Anand; Hudoba, Michael W; Alvarez, Ricardo; Castro, Carlos E; Soghrati, Soheil

    2017-04-01

    Deoxyribonucleic acid (DNA) origami is a method for the bottom-up self-assembly of complex nanostructures for applications, such as biosensing, drug delivery, nanopore technologies, and nanomechanical devices. Effective design of such nanostructures requires a good understanding of their mechanical behavior. While a number of studies have focused on the mechanical properties of DNA origami structures, considering defects arising from molecular self-assembly is largely unexplored. In this paper, we present an automated computational framework to analyze the impact of such defects on the structural integrity of a model DNA origami nanoplate. The proposed computational approach relies on a noniterative conforming to interface-structured adaptive mesh refinement (CISAMR) algorithm, which enables the automated transformation of a binary image of the nanoplate into a high fidelity finite element model. We implement this technique to quantify the impact of defects on the mechanical behavior of the nanoplate by performing multiple simulations taking into account varying numbers and spatial arrangements of missing DNA strands. The analyses are carried out for two types of loading: uniform tensile displacement applied on all the DNA strands and asymmetric tensile displacement applied to strands at diagonal corners of the nanoplate.

  10. Folic acid supplements to prevent neural tube defects: trends in East of Ireland 1996-2002.

    LENUS (Irish Health Repository)

    Ward, M

    2004-10-01

    Promotion of folic acid to prevent neural Tube Defects (NTD) has been ongoing for ten years in Ireland, without a concomitant reduction in the total birth prevalence of NTD. The effectiveness of folic acid promotion as the sole means of primary prevention of NTD is therefore questionable. We examined trends in folic acid knowledge and peri-conceptional use from 1996-2002 with the aim of assessing the value of this approach. From 1996-2002, 300 women attending ante-natal clinics in Dublin hospitals annually were surveyed regarding their knowledge and use of folic acid. During the period the proportion who had heard of folic acid rose from 54% to 94% between 1996 and 2002 (c2 test for trend: p<0.001). Knowledge that folic acid can prevent NTD also rose from 21% to 66% (c2 test for trend: p<0.001). Although the proportion who took folic acid during pregnancy increased from 14% to 83% from 1996 to 2002 (c2 test for trend: p<0.001), peri-conceptional intake did not rise above 24% in any year. There is a high awareness of folic acid and its relation to NTD, which is not matched by peri-conceptional uptake. The main barrier to peri-conceptional uptake is the lack of pregnancy planning. To date promotional campaigns appear to have been ineffective in reducing the prevalence of NTD in Ireland. Consequently, fortification of staple foodstuffs is the only practical and reliable means of primary prevention of NTD.

  11. Free acetate production by rat hepatocytes during peroxisomal fatty acid and dicarboxylic acid oxidation.

    Science.gov (United States)

    Leighton, F; Bergseth, S; Rørtveit, T; Christiansen, E N; Bremer, J

    1989-06-25

    The fate of the acetyl-CoA units released during peroxisomal fatty acid oxidation was studied in isolated hepatocytes from normal and peroxisome-proliferated rats. Ketogenesis and hydrogen peroxide generation were employed as indicators of mitochondrial and peroxisomal fatty acid oxidation, respectively. Butyric and hexanoic acids were employed as mitochondrial substrates, 1, omega-dicarboxylic acids as predominantly peroxisomal substrates, and lauric acid as a substrate for both mitochondria and peroxisomes. Ketogenesis from dicarboxylic acids was either absent or very low in normal and peroxisome-proliferated hepatocytes, but free acetate release was detected at rates that could account for all the acetyl-CoA produced in peroxisomes by dicarboxylic and also by monocarboxylic acids. Mitochondrial fatty acid oxidation also led to free acetate generation but at low rates relative to ketogenesis. The origin of the acetate released was confirmed employing [1-14C]dodecanedioic acid. Thus, the activity of peroxisomes might contribute significantly to the free acetate generation known to occur during fatty acid oxidation in rats and possibly also in humans.

  12. Administration with Bushenkangshuai Tang alleviates UV irradiation- and oxidative stress-induced lifespan defects in nematode Caenorhabditis elegans

    Institute of Scientific and Technical Information of China (English)

    Qi RUI; Qin LU; Dayong WANG

    2009-01-01

    During normal metabolism, oxidative bypro-ducts will inevitably generate and damage molecules thereby impairing their biological functions, including the is a traditional Chinese medicine widely used for clini-cally treating premature ovarian failure. In the present study, BT administration at high concentrations signifi-cantly increased lifespan, slowed aging-related decline, and delayed accumulation of aging-related cellular damage in wild-type Caenorhabditis elegans. BT admin-istration could further largely alleviate the aging defects induced by UV and oxidative stresses, and BT administra-tion at different concentrations could largely rescue the aging defects in mev-1 mutant animals. The protective effects of BT administration on aging process were at least partially dependent on the Ins/IGF-like signaling pathway. Moreover, BT administration at different concentrations obviously altered the expression patterns of antioxidant genes and suppressed the severe stress responses induced by UV and oxidative stresses, suggesting that BT-induced tolerance to UV or oxidative stress might result from reactive oxygen species scavenging. BT administration during development was not necessarily a requirement for UV and oxidative stress resistance, and the concentrations of administrated BT examined were not toxic for nematodes. Therefore, BT administration could effectively retrieve the aging defects induced by UV irradiation and oxidative stress in Caenorhabditis elegans.

  13. Osteochondral defect repair using a polyvinyl alcohol-polyacrylic acid (PVA-PAAc) hydrogel.

    Science.gov (United States)

    Bichara, David A; Bodugoz-Sentruk, Hatice; Ling, Doris; Malchau, Erik; Bragdon, Charles R; Muratoglu, Orhun K

    2014-08-01

    Poly(vinyl alcohol) (PVA) hydrogels can be candidates for articular cartilage repair due to their high water content. We synthesized a PVA-poly(acrylic acid) (PAAc) hydrogel formulation and determined its ability to function as a treatment option for condylar osteochondral (OC) defects in a New Zealand white rabbit (NZWR) model for 12 weeks and 24 weeks. In addition to hydrogel OC implants, tensile bar-shaped hydrogels were also implanted subcutaneously to evaluate changes in mechanical properties as a function of in vivo duration. There were no statistically significant differences (p > 0.05) in the water content measured in the OC hydrogel implant that was harvested after 12 weeks and 24 weeks, and non-implanted controls. There were no statistically significant differences (p > 0.05) in the break stress, strain at break or modulus of the tensile bars either between groups. Histological analysis of the OC defect, synovial capsule and fibrous tissue around the tensile bars determined hydrogel biocompatibility. Twelve-week hydrogels were found to be in situ flush with the articular cartilage; meniscal tissue demonstrated an intact surface. Twenty-four week hydrogels protruded from the defect site due to lack of integration with subchondral tissue, causing fibrillation to the meniscal surface. Condylar micro-CT scans ruled out osteolysis and bone cysts of the subchondral bone, and no PVA-PAAc hydrogel contents were found in the synovial fluid. The PVA-PAAc hydrogel was determined to be fully biocompatible, maintained its properties over time, and performed well at the 12 week time point. Physical fixation of the PVA-PAAc hydrogel to the subchondral bone is required to ensure long-term performance of hydrogel plugs for OC defect repair.

  14. Modulation of electronic properties of tin oxide nanobelts via thermal control of surface oxygen defects

    Science.gov (United States)

    Keiper, Timothy D.; Barreda, Jorge L.; Zheng, Jim P.; Xiong, Peng

    2017-02-01

    Nanomaterials made from binary metal oxides are of increasing interest because of their versatility in applications from flexible electronics to portable chemical and biological sensors. Controlling the electrical properties of these materials is the first step in device implementation. Tin dioxide (SnO2) nanobelts (NB) synthesized by the vapor-liquid-solid mechanism have shown much promise in this regard. We explore the modification of devices prepared with single crystalline NBs by thermal annealing in vacuum and oxygen, resulting in a viable field-effect transistor (FET) for numerous applications at ambient temperature. An oxygen annealing step initially increases the device conductance by up to a factor of 105, likely through the modification of the surface defects of the NB, leading to Schottky barrier limited devices. A multi-step annealing procedure leads to further increase of the conductance by approximately 350% and optimization of the electronic properties. The effects of each step is investigated systematically on a single NB. The optimization of the electrical properties of the NBs makes possible the consistent production of channel-limited FETs and control of the device performance. Understanding these improvements on the electrical properties over the as-grown materials provides a pathway to enhance and tailor the functionalities of tin oxide nanostructures for a wide variety of optical, electronic, optoelectronic, and sensing applications that operate at room temperature.

  15. A method for measuring fatty acid oxidation in C. elegans

    DEFF Research Database (Denmark)

    Elle, Ida Coordt; Rødkær, Steven Vestergaard; Fredens, Julius;

    2012-01-01

    The nematode C. elegans has during the past decade proven to be a valuable model organism to identify and examine molecular mechanisms regulating lipid storage and metabolism. While the primary approach has been to identify genes and pathways conferring alterations in lipid accumulation, only a few...... recent studies have recognized the central role of fatty acid degradation in cellular lipid homeostasis. In the present study, we show how complete oxidation of fatty acids can be determined in live C. elegans by examining oxidation of tritium-labeled fatty acids to tritiated H2O that can be measured......, the present methodology can be used to delineate the role of specific genes and pathways in the regulation of β-oxidation in C. elegans....

  16. Zwitterionic versus canonical amino acids over the various defects in zeolites: a two-layer ONIOM calculation.

    Science.gov (United States)

    Yang, Gang; Zhou, Lijun

    2014-10-13

    Defects are often considered as the active sites for chemical reactions. Here a variety of defects in zeolites are used to stabilize zwitterionic glycine that is not self-stable in gas phase; in addition, effects of acidic strengths and zeolite channels on zwitterionic stabilization are demonstrated. Glycine zwitterions can be stabilized by all these defects and energetically prefer to canonical structures over Al and Ga Lewis acidic sites rather than Ti Lewis acidic site, silanol and titanol hydroxyls. For titanol (Ti-OH), glycine interacts with framework Ti and hydroxyl sites competitively, and the former with Lewis acidity predominates. The transformations from canonical to zwitterionic glycine are obviously more facile over Al and Ga Lewis acidic sites than over Ti Lewis acidic site, titanol and silanol hydroxyls. Charge transfers that generally increase with adsorption energies are found to largely decide the zwitterionic stabilization effects. Zeolite channels play a significant role during the stabilization process. In absence of zeolite channels, canonical structures predominate for all defects; glycine zwitterions remain stable over Al and Ga Lewis acidic sites and only with synergy of H-bonding interactions can exist over Ti Lewis acidic site, while automatically transform to canonical structures over silanol and titanol hydroxyls.

  17. Light Enhanced Hydrofluoric Acid Passivation: A Sensitive Technique for Detecting Bulk Silicon Defects.

    Science.gov (United States)

    Grant, Nicholas E

    2016-01-01

    A procedure to measure the bulk lifetime (>100 µsec) of silicon wafers by temporarily attaining a very high level of surface passivation when immersing the wafers in hydrofluoric acid (HF) is presented. By this procedure three critical steps are required to attain the bulk lifetime. Firstly, prior to immersing silicon wafers into HF, they are chemically cleaned and subsequently etched in 25% tetramethylammonium hydroxide. Secondly, the chemically treated wafers are then placed into a large plastic container filled with a mixture of HF and hydrochloric acid, and then centered over an inductive coil for photoconductance (PC) measurements. Thirdly, to inhibit surface recombination and measure the bulk lifetime, the wafers are illuminated at 0.2 suns for 1 min using a halogen lamp, the illumination is switched off, and a PC measurement is immediately taken. By this procedure, the characteristics of bulk silicon defects can be accurately determined. Furthermore, it is anticipated that a sensitive RT surface passivation technique will be imperative for examining bulk silicon defects when their concentration is low (<10(12) cm(-3)).

  18. Neural tube defect surveillance and folic acid intervention--Texas-Mexico border, 1993-1998.

    Science.gov (United States)

    2000-01-14

    Neural tube defects (NTDs) are common and serious malformations that originate early in pregnancy. In the United States, approximately 4000 pregnancies each year are affected by the two most common NTDs (spina bifida and anencephaly). In 1992, the Texas Department of Health (TDH), with support from a CDC cooperative agreement, implemented the Texas Neural Tube Defect Project (TNTDP), a program of NTD surveillance and risk-reduction activities in the 14 counties that border Mexico. The project was initiated in response to an anencephaly cluster identified during 1990-1991 in Brownsville (Cameron County), Texas (1). Whether the high anencephaly rate (19.7 per 10,000 live births) was unique to Cameron County or was characteristic of the entire border was unknown. This report summarizes NTD surveillance rates for the 14 Texas-Mexico border counties for 1993-1998 and presents preliminary results of TNTDP efforts to prevent the recurrence of NTDs by providing folic acid to high-risk women. Findings indicate that the baseline rate along the border is high (13.4 per 10,000 live births) and largely reflects the rate among Hispanics (13.8). Although a longer period is needed to obtain definitive results, folic acid appears to be effective for reducing the risk for NTD recurrence in Hispanics.

  19. Measurement and modelling of the defect chemistry and transport properties of ceramic oxide mixed ionic and electronic conductors

    NARCIS (Netherlands)

    Dalslet, Bjarke Thomas

    2008-01-01

    The mixed ionic and electronic conducting fluorite and perovskite materials examined in this thesis are all oxide ion conducting materials. The defect chemistry and transport properties of a number of these materials are measured using: 1) a measurement technique using an oxygen pump and an electrol

  20. Defect engineered d{sup 0} ferromagnetism in tin-doped indium oxide nanostructures and nanocrystalline thin-films

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Gobinda Gopal, E-mail: gobinda.gk@gmail.com, E-mail: sghoshphysics@gmail.com; Sarkar, Ayan [Centre for Research in Nanoscience and Nanotechnology, University of Calcutta, Technology Campus, Block JD-2, Sector III, Salt Lake City, Kolkata 700 098 (India); Ghosh, Shyamsundar, E-mail: gobinda.gk@gmail.com, E-mail: sghoshphysics@gmail.com [Department of Physics, Bejoy Narayan Mahavidyalaya, P.O. Itachuna, Hooghly 712 147 (India); Mandal, Guruprasad; Mukherjee, Goutam Dev [Department of Physical Sciences, Indian Institute of Science Education and Research, Kolkata, Mohanpur Campus, BCKV Campus Main Office, Nadia 741 252 (India); Manju, Unnikrishnan [Materials Characterization Division, CSIR-Central Glass and Ceramic Research Institute, 2A & 2B Raja S. C. Mullick Road, Jadavpur, Kolkata 700 032 (India); Banu, Nasrin; Dev, Bhupendra Nath [Department of Material Science, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Jadavpur, Kolkata 700 032 (India)

    2015-08-21

    Origin of unexpected defect engineered room-temperature ferromagnetism observed in tin-doped indium oxide (ITO) nanostructures (Nanowires, Nano-combs) and nanocrystalline thin films fabricated by pulsed laser deposition has been investigated. It is found that the ITO nanostructures prepared under argon environment exhibit strongest ferromagnetic signature as compared to that nanocrystalline thin films grown at oxygen. The evidence of singly ionized oxygen vacancy (V{sub 0}{sup +}) defects, obtained from various spectroscopic measurements, suggests that such V{sub 0}{sup +} defects are mainly responsible for the intrinsic ferromagnetic ordering. The exchange interaction of the defects provides extensive opportunity to tune the room-temperature d{sup 0} ferromagnetism and optical properties of ITOs.

  1. Role of tartaric and malic acids in wine oxidation.

    Science.gov (United States)

    Danilewicz, John C

    2014-06-04

    Tartaric acid determines the reduction potential of the Fe(III)/Fe(II) redox couple. Therefore, it is proposed that it determines the ability of Fe to catalyze wine oxidation. The importance of tartaric acid was demonstrated by comparing the aerial oxidation of 4-methylcatechol (4-MeC) in model wine made up with tartaric and acetic acids at pH 3.6. Acetic acid, as a weaker Fe(III) ligand, should raise the reduction potential of the Fe couple. 4-MeC was oxidized in both systems, but the mechanisms were found to differ. Fe(II) readily reduced oxygen in tartrate model wine, but Fe(III) alone failed to oxidize the catechol, requiring sulfite assistance. In acetate model wine the reverse was found to operate. These observations should have broad application to model systems designed to study the oxidative process in foods and other beverages. Consideration should be given to the reduction potential of metal couples by the inclusion of appropriate ligands.

  2. Loss of Adipose Fatty Acid Oxidation Does Not Potentiate Obesity at Thermoneutrality

    Directory of Open Access Journals (Sweden)

    Jieun Lee

    2016-02-01

    Full Text Available Ambient temperature affects energy intake and expenditure to maintain homeostasis in a continuously fluctuating environment. Here, mice with an adipose-specific defect in fatty acid oxidation (Cpt2A−/− were subjected to varying temperatures to determine the role of adipose bioenergetics in environmental adaptation and body weight regulation. Microarray analysis of mice acclimatized to thermoneutrality revealed that Cpt2A−/− interscapular brown adipose tissue (BAT failed to induce the expression of thermogenic genes such as Ucp1 and Pgc1α in response to adrenergic stimulation, and increasing ambient temperature exacerbated these defects. Furthermore, thermoneutral housing induced mtDNA stress in Cpt2A−/− BAT and ultimately resulted in a loss of interscapular BAT. Although the loss of adipose fatty acid oxidation resulted in clear molecular, cellular, and physiologic deficits in BAT, body weight gain and glucose tolerance were similar in control and Cpt2A−/− mice in response to a high-fat diet, even when mice were housed at thermoneutrality.

  3. Rare earth element partitioning between hydrous ferric oxides and acid mine water during iron oxidation

    Science.gov (United States)

    Verplanck, P.L.; Nordstrom, D.K.; Taylor, H.E.; Kimball, B.A.

    2004-01-01

    Ferrous iron rapidly oxidizes to Fe (III) and precipitates as hydrous Fe (III) oxides in acid mine waters. This study examines the effect of Fe precipitation on the rare earth element (REE) geochemistry of acid mine waters to determine the pH range over which REEs behave conservatively and the range over which attenuation and fractionation occur. Two field studies were designed to investigate REE attenuation during Fe oxidation in acidic, alpine surface waters. To complement these field studies, a suite of six acid mine waters with a pH range from 1.6 to 6.1 were collected and allowed to oxidize in the laboratory at ambient conditions to determine the partitioning of REEs during Fe oxidation and precipitation. Results from field experiments document that even with substantial Fe oxidation, the REEs remain dissolved in acid, sulfate waters with pH below 5.1. Between pH 5.1 and 6.6 the REEs partitioned to the solid phases in the water column, and heavy REEs were preferentially removed compared to light REEs. Laboratory experiments corroborated field data with the most solid-phase partitioning occurring in the waters with the highest pH. ?? 2004 Elsevier Ltd. All rights reserved.

  4. Oxidation in fish oil enriched mayonnaise: ascorbic acid and low pH increase oxidative deterioration.

    Science.gov (United States)

    Jacobsen, C; Timm, M; Meyer, A S

    2001-08-01

    The effect of ascorbic acid (0-4000 ppm) and pH (3.8-6.2) on oxidation and levels of iron and copper in various fractions of mayonnaise enriched with 16% fish oil was investigated. Ascorbic acid induced release of iron from the assumed oil-water interface into the aqueous phase at all pH levels, but this effect of ascorbic acid was strongest at low pH (pH 3.8-4.2). Ascorbic acid generally promoted formation of volatile oxidation compounds and reduced the peroxide value in mayonnaises. Peroxide values and total volatiles generally increased with decreasing pH values, suggesting that low pH promoted oxidation. It is proposed that iron bridges between the egg yolk proteins low-density lipoproteins, lipovitellin, and phosvitin at the oil-water interface are broken at low pH values, whereby iron ions become accessible as oxidation initiators. In the presence of ascorbic acid, oxidation is further enhanced due to the reduction of Fe(3+) to Fe(2+) that rapidly catalyzes lipid oxidation via lipid hydroperoxide decomposition at the oil-water interface in mayonnaise.

  5. [Acute fatty liver in pregnancy: revealing fetal fatty acid oxidation disorders].

    Science.gov (United States)

    Lamireau, D; Feghali, H; Redonnet-Vernhet, I; Mesli, S; Carles, D; Brissaud, O

    2012-03-01

    Acute fatty liver of pregnancy (AFLP) and hemolysis, elevated liver enzymes, and low platelet count (HELLP) syndrome are serious maternal illnesses occurring in the third trimester of pregnancy with significant perinatal and maternal mortality. AFLP may result from mitochondrial defects in the beta-oxidation of fatty acids, in particular a deficiency of the long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) in the fetus. Clinical findings in AFLP vary and its diagnosis is complicated by a significant overlap in clinical and biochemical features with HELLP syndrome. We report the case of 2 siblings who died, the first one in the neonatal period of asphyxia with multivisceral presentation and the second one from sudden death at 7 months. Autopsy of the latter infant revealed hepatic steatosis associated with cardiomyopathy, which led to suspicion of a fatty acid oxidation deficiency. Mutation analysis demonstrated that both children were homozygous for the common mutation c.1528G>C and the parents were heterozygous for this same mutation. This case demonstrates the importance of screening mothers with acute fatty liver disease of pregnancy and their children at birth for a metabolic disease. This article proposes several metabolic tests for mother and child suspected of having beta-oxidation of a fatty acid disorder.

  6. alpha-Lipoic acid and ascorbate prevent LDL oxidation and oxidant stress in endothelial cells.

    Science.gov (United States)

    Sabharwal, Anup K; May, James M

    2008-02-01

    Both alpha-lipoic acid (LA) and ascorbic acid (vitamin C) have been shown to improve endothelial dysfunction, a precursor of atherosclerosis. Since oxidant stress can cause endothelial dysfunction, we tested the interaction and efficacy of these antioxidants in preventing oxidant damage to lipids due to both intra- and extracellular oxidant stresses in EA.hy926 endothelial cells. LA spared intracellular ascorbate in culture and in response to an intracellular oxidant stress induced by the redox cycling agent menadione. Extracellular oxidant stress generated by incubating cells for 2 h in with 0.2 mg/ml LDL and 5 muM Cu2+ caused a time-dependent increase of the lipid peroxidation product malondialdehyde in both cells and LDL, preceded by rapid disappearance of; alpha-tocopherol in LDL. alpha-Lipoic acid at concentrations of 40-80 microM blunted these effects. Similarly, intracellular ascorbate concentrations of 1-2 mM also prevented Cu2+-induced lipid peroxidation in LDL and cells. Cu2+-dependent oxidation of LDL in the presence of ascorbate-loaded cells decreased intracellular ascorbate by 20%, but this decrease was not reversed by LA. Both LA and ascorbate protect endothelial cells and LDL from either intra- or extracellular oxidant stress, but that LA does not spare ascorbate in oxidatively stressed cells.

  7. Acetylsalicylic acid and acetaminophen protect against oxidative neurotoxicity.

    Science.gov (United States)

    Maharaj, H; Maharaj, D S; Daya, S

    2006-09-01

    Due to the implication of oxidative stress in neurodegenerative disorders we decided to investigate the antioxidant properties of acetylsalicylic acid and acetaminophen either alone or in combination. The thiobarbituric acid assay (TBA) and the nitroblue tetrazolium (NBT) assay were used to investigate quinolinic acid (QA)-induced: lipid peroxidation and superoxide anion generation in the rat hippocampus, in vivo. The study also shows, using cresyl violet staining, the preservation of structural integrity of neuronal cells following treatment with acetylsalicylic acid and acetaminophen in QA-lesioned rat hippocampus. Furthermore the study sought to determine whether these agents have any effect on endogenous (QA) formation. This study shows that acetylsalicylic acid and acetaminophen inhibit QA-induced superoxide anion generation, lipid peroxidation and cell damage, in vivo, in the rat hippocampus. In addition these agents inhibit the enzyme, 3-hydroxyanthranilic acid oxygenase (3-HAO), responsible for the synthesis of endogenous QA.

  8. Oxidation in fish oil enriched mayonnaise : Ascorbic acid and low pH increase oxidative deterioration

    DEFF Research Database (Denmark)

    Jacobsen, Charlotte; Timm Heinrich, Maike; Meyer, Anne S.

    2001-01-01

    The effect of ascorbic acid (0-4000 ppm) and pH (3.8-6.2) on oxidation and levels of iron and copper in various fractions of mayonnaise enriched with 16% fish oil was investigated. Ascorbic acid induced release of iron from the assumed oil- water interface into the aqueous phase at all pH levels......, but this effect of ascorbic acid was strongest at low pH (pH 3.8- 4.2). Ascorbic acid generally promoted formation of volatile oxidation compounds and reduced the peroxide value in mayonnaises. Peroxide values and total volatiles generally increased with decreasing pH values, suggesting that low pH promoted...... due to the reduction of Fe3+ to Fe2+ that rapidly catalyzes lipid oxidation via lipid hydroperoxide decomposition at the oil-water interface in mayonnaise...

  9. Synthesis and Defect Structure Analysis of Complex Oxides for Li-Ion Battery Electrodes

    Science.gov (United States)

    Hao, Xiaoguang

    Lithium-ion batteries have attracted increased attention for energy storage development due to the vast demand from portable electronics, (hybrid) electric vehicles and future power grids. The research in this dissertation is focused on the development of oxide electrodes for lithium-ion batteries with high power density and improved stability. One of the promising cathodes for lithium-ion batteries is lithium manganospinel (LiMn2O4). However, this compound suffers from manganese dissolution and a Jahn-Teller distortion due to Mn3+, especially in oxygen deficient LiMn2O4-delta. Hydrothermal based synthesis methods were developed to eliminate oxygen vacancies to enable high power in cathodes composed of nano-sized spinel particles. The relationship between oxygen defects and the capacity fading mechanism was demonstrated, and collapse of the mechanical structure was identified in defect-rich LiMn 2O4-delta. Next, the nickel substituted manganospinel, LiNi0.5Mn 1.5O4 shows unexpected high voltage side reactions. To overcome this drawback, a thin and chemically inert titanate was used as an artificial SEI (solid electrolyte interface) coating to prohibit transition-metal dissolution and parasitic side reactions, which led to a 200% improvement of the capacity retention at 55°C and negligible polarization losses. Finally, the spinel-structured lithium titanate (Li 4Ti5O12) is introduced as an anode material for lithium-ion batteries due to its higher operating potential and excellent structural stability compared to current graphite anodes. However, the poor electronic conductivity and low lithium diffusion coefficient hinder its wide application. Given these advantages, a facile, low-cost solution method is explored to synthesize nano-sized titanates. Rapid charge/ discharge was achieved up to rates of 100 C (36 second charge/ discharge) due to a shorter lithium mean-free path and better contact between the active material and conductive agents.

  10. Hypotrophy of conduit artery walls of the offspring of nitric oxide-defective rats.

    Science.gov (United States)

    Kristek, F; Gerová, M

    2004-04-01

    The objective of the present study was to investigate the structure of the arterial walls of the offspring stemming from nitric oxide (NO)-defective hypertensive parents. The parents were treated with NG-nitro-L-arginine methyl ester (40 mg kg-1 day-1) for 5 weeks. Blood pressure was measured noninvasively in six 30-day-old rats and nine age-matched controls. The cardiovascular system was perfused with glutaraldehyde at 120 mmHg. The thoracic aorta and carotid artery were processed for electron microscopy, and geometry was determined by light microscopy. Endothelial cells, smooth muscle cells (SMC) and extracellular matrix (ECM) were determined by the point counting method in electron micrographs of the carotid artery. The blood pressure of experimental offspring was 150.0 +/- 2.3 vs 104.6 +/- 2.1 mmHg (P hypotrophy. The wall thickness (tunica intima and media) of the thoracic aorta and carotid artery of experimental offspring was decreased to 78.9% (P < 0.01) and 83.8% (P < 0.01), respectively, compared to controls, as confirmed by a respective cross-sectional area of 85.3% (P < 0.01) and 84.1% (P < 0.01). The wall thickness/inner diameter ratio was reduced to 75% (P < 0.01) in the thoracic artery and to 81.5% (P < 0.01) in the carotid artery. No change in endothelial cell volume density or ECM was observed in the tunica intima of the carotid artery, and SMC volume density was lower in the tunica media (37.6 +/- 0.9 vs 44.7 +/- 1.1% for controls, P < 0.01), indicating compromised SMC development. Interference with arginine metabolism, a decrease in NO, and other factors are possible mechanisms underlying the structural alterations of the cardiovascular system of offspring from NO-defective hypertensive rats.

  11. Prevention of neural tube defects with folic acid: The Chinese experience.

    Science.gov (United States)

    Ren, Ai-Guo

    2015-08-08

    Neural tube defects (NTDs) are a group of congenital malformations of the central nervous system that are caused by the closure failure of the embryonic neural tube by the 28(th) day of conception. Anencephaly and spina bifida are the two major subtypes. Fetuses with anencephaly are often stillborn or electively aborted due to prenatal diagnosis, or they die shortly after birth. Most infants with spina bifida are live-born and, with proper surgical treatment, can survive into adulthood. However, these children often have life-long physical disabilities. China has one of the highest prevalence of NTDs in the world. Inadequate dietary folate intake is believed to be the main cause of the cluster. Unlike many other countries that use staple fortification with folic acid as the public health strategy to prevent NTDs, the Chinese government provides all women who have a rural household registration and who plan to become pregnant with folic acid supplements, free of charge, through a nation-wide program started in 2009. Two to three years after the initiation of the program, the folic acid supplementation rate increased to 85% in the areas of the highest NTD prevalence. The mean plasma folate level of women during early and mid-pregnancy doubled the level before the program was introduced. However, most women began taking folic acid supplements when they knew that they were pregnant. This is too late for the protection of the embryonic neural tube. In a post-program survey of the women who reported folic acid supplementation, less than a quarter of the women began taking supplements prior to pregnancy, indicating that the remaining three quarters of the fetuses remained unprotected during the time of neural tube formation. Therefore, staple food fortification with folic acid should be considered as a priority in the prevention of NTDs.

  12. Oxidative cleavage of erucic acid for the synthesis of brassylic acid

    Energy Technology Data Exchange (ETDEWEB)

    Mohammed J. Nasrullah; Pooja Thapliyal; Erica N. Pfarr; Nicholas S. Dusek; Kristofer L. Schiele; James A. Bahr

    2010-10-29

    The main focus of this work is to synthesize Brassylic Acid (BA) using oxidative cleavage of Erucic Acid (EA). Crambe (Crambe abyssinica) is an industrial oilseed grown in North Dakota. Crambe has potential as an industrial fatty acid feedstock as a source of Erucic acid (EA). It has approximately 50-60 % of EA, a C{sub 22} monounsaturated fatty acid. Oxidative cleavage of unsaturated fatty acids derived from oilseeds produces long chain (9, 11, and 13 carbon atoms) dibasic and monobasic acids. These acids are known commercial feedstocks for the preparation of nylons, polyesters, waxes, surfactants, and perfumes. Other sources of EA are Rapeseed seed oil which 50-60 % of EA. Rapeseed is grown outside USA. The oxidative cleavage of EA was done using a high throughput parallel pressure reactor system. Kinetics of the reaction shows that BA yields reach a saturation at 12 hours. H{sub 2}WO{sub 4} was found to be the best catalyst for the oxidative cleavage of EA. High yields of BA were obtained at 80 C with bubbling of O{sub 2} or 10 bar of O{sub 2} for 12 hours.

  13. Human placenta metabolizes fatty acids: implications for fetal fatty acid oxidation disorders and maternal liver diseases.

    Science.gov (United States)

    Shekhawat, Prem; Bennett, Michael J; Sadovsky, Yoel; Nelson, D Michael; Rakheja, Dinesh; Strauss, Arnold W

    2003-06-01

    The role of fat metabolism during human pregnancy and in placental growth and function is poorly understood. Mitochondrial fatty acid oxidation disorders in an affected fetus are associated with maternal diseases of pregnancy, including preeclampsia, acute fatty liver of pregnancy, and the hemolysis, elevated liver enzymes, and low platelets syndrome called HELLP. We have investigated the developmental expression and activity of six fatty acid beta-oxidation enzymes at various gestational-age human placentas. Placental specimens exhibited abundant expression of all six enzymes, as assessed by immunohistochemical and immunoblot analyses, with greater staining in syncytiotrophoblasts compared with other placental cell types. beta-Oxidation enzyme activities in placental tissues were higher early in gestation and lower near term. Trophoblast cells in culture oxidized tritium-labeled palmitate and myristate in substantial amounts, indicating that the human placenta utilizes fatty acids as a significant metabolic fuel. Thus human placenta derives energy from fatty acid oxidation, providing a potential explanation for the association of fetal fatty acid oxidation disorders with maternal liver diseases in pregnancy.

  14. Lewis acidity enhancement of triarylborane by appended phosphine oxide groups.

    Science.gov (United States)

    Kwak, Jaewoo; Nghia, Nguyen Van; Lee, Junseong; Kim, Hyoseok; Park, Myung Hwan; Lee, Min Hyung

    2015-03-14

    A series of mono-, di-, and tri-phosphine oxide substituted triarylboranes, Mes2BAr (1), MesBAr2 (2), and BAr3 (3) (Ar = 4-(Ph2PO)-2,6-Me2-C6H2) were prepared to investigate the effect of a phosphine oxide group (Ph2PO) on Lewis acidity enhancement of triarylboranes. The X-ray crystal structure of 3 revealed peripheral decoration of Ph2PO groups with a C3-axis perpendicular to the trigonal boron center. UV/Vis absorption and PL spectra indicated a significant contribution of π(Mes or phenylene) → pπ(B) charge transfer in the lower-energy electronic transition. The reduction potential measured by cyclic voltammetry showed apparent LUMO stabilization by introduction of phosphine oxide groups, the extent of which gradually increased with the increasing number of phosphine oxide groups. Lewis acidity enhancement was also supported by the gradual increase in fluoride ion affinity in the order 3 > 2 > 1. Theoretical calculations suggest that introduction of a Ph2PO group into a triarylborane significantly enhances the Lewis acidity of the boron center via an inductive electron-withdrawing effect and this effect is additive for multiple phosphine oxide groups.

  15. Assays for urinary biomarkers of oxidatively damaged nucleic acids

    DEFF Research Database (Denmark)

    Weimann, Allan; Broedbaek, Kasper; Henriksen, Trine;

    2012-01-01

    and skills requirement. The available ELISA methods present considerable specificity problems and cannot be recommended at present. The oxidized nucleic acid metabolites in urine are assumed to originate from the DNA and RNA. However, direct evidence is not available. A possible contribution from...

  16. The promiscuous enzyme medium-chain 3-keto-acyl-CoA thiolase triggers a vicious cycle in fatty-acid beta-oxidation

    NARCIS (Netherlands)

    Martines, Anne-Claire M. F.; van Eunen, Karen; Reijngoud, Dirk-Jan; Bakker, Barbara M.

    2017-01-01

    Mitochondrial fatty-acid beta-oxidation (mFAO) plays a central role in mammalian energy metabolism. Multiple severe diseases are associated with defects in this pathway. Its kinetic structure is characterized by a complex wiring of which the functional implications have hardly been explored. Repetit

  17. Chloramines and hypochlorous acid oxidize erythrocyte peroxiredoxin 2.

    Science.gov (United States)

    Stacey, Melissa M; Peskin, Alexander V; Vissers, Margreet C; Winterbourn, Christine C

    2009-11-15

    Peroxiredoxin 2 (Prx2) is an abundant thiol protein that is readily oxidized in erythrocytes exposed to hydrogen peroxide. We investigated its reactivity in human erythrocytes with hypochlorous acid (HOCl) and chloramines, relevant oxidants in inflammation. Prx2 was oxidized to a disulfide-linked dimer by HOCl, glycine chloramine (GlyCl), and monochloramine (NH(2)Cl) in a dose-dependent manner. In the absence of added glucose, Prx2 and GSH showed similar sensitivities. Second-order rate constants for the reactions of Prx2 with NH(2)Cl and GlyCl were 1.5 x 10(4) and 8 M(-1) s(-1), respectively. The NH(2)Cl value is approximately 10 times higher than that for GSH, whereas Prx2 is approximately 30 times less sensitive than GSH to GlyCl. Thus, the relative sensitivity of Prx2 to GlyCl is greater in the erythrocyte. Oxidation of erythrocyte Prx2 and GSH was less in the presence of glucose, probably because of recycling. High doses of NH(2)Cl resulted in incomplete regeneration of reduced Prx2, suggesting impairment of the recycling mechanism. Our results show that, although HOCl and chloramines are less selective than H(2)O(2), they nevertheless oxidize Prx2. Exposure to these inflammatory oxidants will result in Prx2 oxidation and could compromise the erythrocyte's ability to resist damaging oxidative insult.

  18. Oxidation in fish oil enriched mayonnaise : Ascorbic acid and low pH increase oxidative deterioration

    DEFF Research Database (Denmark)

    Jacobsen, Charlotte; Timm Heinrich, Maike; Meyer, Anne S.

    2001-01-01

    oxidation. It is proposed that iron bridges between the egg yolk proteins low-density lipoproteins, lipovitellin, and phosvitin at the oil-water interface are broken at low pH values, whereby iron ions become accessible as oxidation initiators. In the presence of ascorbic acid, oxidation is further enhanced......The effect of ascorbic acid (0-4000 ppm) and pH (3.8-6.2) on oxidation and levels of iron and copper in various fractions of mayonnaise enriched with 16% fish oil was investigated. Ascorbic acid induced release of iron from the assumed oil- water interface into the aqueous phase at all pH levels......, but this effect of ascorbic acid was strongest at low pH (pH 3.8- 4.2). Ascorbic acid generally promoted formation of volatile oxidation compounds and reduced the peroxide value in mayonnaises. Peroxide values and total volatiles generally increased with decreasing pH values, suggesting that low pH promoted...

  19. Irradiation temperature dependence of production efficiency of lattice defects in some neutron-irradiated oxides

    Energy Technology Data Exchange (ETDEWEB)

    Okada, Moritami [Research Reactor Institute, Kyoto University, Kumatori-cho, Sennan-gun, Osaka 5900494 (Japan)]. E-mail: okada@rri.kyoto-u.ac.jp; Atobe, Kozo [Faculty of Science, Naruto University of Education, Naruto, Tokushima 7728502 (Japan); Nakagawa, Masuo [Faculty of Education, Kagawa University, Takamatsu, Kagawa 7608522 (Japan)

    2004-11-01

    Temperature dependence of production efficiency of irradiation-induced defects in neutron-irradiated oxides has been investigated. Some oxide single crystals, MgO, {alpha}-Al{sub 2}O{sub 3} (sapphire) and TiO{sub 2} (rutile), were irradiated at several controlled temperatures, 10, 20, 50, 100, 150 and 200 K, using the low-temperature irradiation facility of Kyoto University Reactor (KUR-LTL), and at ambient temperature ({approx}370 K) in the same facility. Irradiation temperature dependence of production efficiency of a 1 {mu}m band in TiO{sub 2} differs greatly from that of anion vacancy (F-type centers) in MgO and {alpha}-Al{sub 2}O{sub 3}. Results for MgO and {alpha}-Al{sub 2}O{sub 3} show steep negative gradients from 10 to 370 K, whereas that for TiO{sub 2} includes a valley between 40 and 60 K and a hump at about 130 K, and then disappear at about 200 K. In MgO and {alpha}-Al{sub 2}O{sub 3}, this behavior can be explained by the recombination of Frenkel pairs, which is activated at higher temperature. In TiO{sub 2}, in addition to the recombination mechanism, a covalent bonding property is thought to be exerted strong influence, and it is suggested that a disappearance of the 1 {mu}m band at above 200 K is due to the recombination process of Frenkel pairs which is caused by the irradiation-induced crystallization.

  20. Reduction of birth prevalence rates of neural tube defects after folic acid fortification in Chile.

    Science.gov (United States)

    López-Camelo, Jorge S; Orioli, Iêda M; da Graça Dutra, Maria; Nazer-Herrera, Julio; Rivera, Nelson; Ojeda, María Elena; Canessa, Aurora; Wettig, Elisabeth; Fontannaz, Ana María; Mellado, Cecília; Castilla, Eduardo E

    2005-06-01

    To verify whether the decreasing neural tube defects birth prevalence rates in Chile are due to folic acid fortification or to pre-existing decreasing trends, we performed a population survey using a network of Estudio Colaborativo Latino Americano de Malformaciones Congenitas (ECLAMC, Latin American Collaborative Study of Congenital Malformations) maternity hospitals in Chile, between the years 1982 and 2002. Within each maternity hospital, birth prevalence rates of spina bifida and anencephaly were calculated from two pre-fortification periods (1982-1989 and 1990-2000), and from one fortified period (2001-2002). There was no historical trend for spina bifida birth prevalence rates before folic acid fortification, and there was a 51% (minimum 27%, maximum 66%) decrease in the birth prevalence rates of this anomaly in the fortified period. The relative risks of spina bifida were homogeneous among hospitals in the two period comparisons. There was no historical trend for the birth prevalence of anencephaly comparing the two pre-fortified periods, but the relative risks were heterogeneous among hospitals in this comparison. There was a 42% (minimum 10%, maximum 63%) decrease in the birth prevalence rate of anencephaly in the fortified period as compared with the immediately pre-fortified period, with homogeneous relative risks among hospitals. Within the methodological constraints of this study we conclude that the birth prevalence rates for both spina bifida and anencephaly decreased as a result of folic acid fortification, without interference of decreasing secular trends.

  1. [Folic acid supplementation as prophylaxis of neural tube defect in the Lower Silesia region: fact or fiction?].

    Science.gov (United States)

    Bagłaj, Maciej; Wojtyłko, Anna

    2011-01-01

    To assess the efficacy of nationwide programme of prophylaxis of neural tube defects in the Lower Silesia region. A questionnaire study was conducted among all mothers of infants admitted between 2001 and 2010 to the Department of Pediatric Surgery and Urology in Wroclaw Medical Academy. The data regarding pregnancy and delivery, newborn's medical condition, family history, parental health, profession and education, and finally folic acid supplementation by mothers were analysed. Among 1278 newborn infants, in 148 children (11.6%) central nervous system (CNS) defects were diagnosed. Among 894 mothers (69.9%) who took part in the study, 159 of them (17.8%) confirmed taking folic acid before becoming pregnant. The rate of supplementation with folic acid showed a rising trend in the study period and increased from 7.1% in 2001 to 35.8% in 2010. Folic acid was taken more frequently by the women living in urban areas (24.2%) than by those living in rural regions (9.2%). With regard to the educational level, the highest rate of supplementation with folic acid was noted among the women with high education (37.8%). Forty-eight percent of mothers were informed about prevention of neural tube defects by their physician, while in 32% of them the family or media were the source of information. Mothers of 255 infants confirmed that they knew about prevention of congenital defects by vitamin intake, but they had not taken folic acid before pregnancy. 1. Realization of the programme of prevention of neural tube defects in Lower Silesia region is highly unsatisfactory. 2. The actions undertaken on the national and local level and aimed to popularize the knowledge about prevention of CNS defects among women are assessed to be ineffective in the Lower Silesia region and need urgent verification.

  2. Ab initio and kinetic modeling studies of formic acid oxidation

    DEFF Research Database (Denmark)

    Marshall, Paul; Glarborg, Peter

    2015-01-01

    A detailed chemical kinetic model for oxidation of formic acid (HOCHO) in flames has been developed, based on theoretical work and data from literature. Ab initio calculations were used to obtain rate coefficients for reactions of HOCHO with H, O, and HO2. Modeling predictions with the mechanism...... as the fate of HOCO, determines the oxidation rate of formic acid. At lower temperatures HO2, formed from HOCO + O2, is an important chain carrier and modeling predictions become sensitive to the HOCHO + HO2 reaction. © 2014 The Combustion Institute....... on calculations with the kinetic model. Formic acid is consumed mainly by reaction with OH, yielding OCHO, which dissociates rapidly to CO2 + H, and HOCO, which may dissociate to CO + OH or CO2 + H, or react with H, OH, or O2 to form more stable products. The branching fraction of the HOCHO + OH reaction, as well...

  3. Folic acid supplementation influences the distribution of neural tube defect subtypes: A registry-based study.

    Science.gov (United States)

    Bergman, J E H; Otten, E; Verheij, J B G M; de Walle, H E K

    2016-01-01

    Periconceptional folic acid (FA) reduces neural tube defect (NTD) risk, but seems to have a varying effect per NTD subtype. We aimed to study the effect of FA supplementation on NTD subtype distribution using data from EUROCAT Northern Netherlands. We included all birth types with non-syndromal NTDs born in 1997-2012. By Fisher's exact test we analyzed possible differences in NTD subtype distribution between a correct FA supplementation group and incorrect FA supplementation group. We found proportionally fewer cervical/thoracic spina bifida cases and more lumbar/sacral spina bifida cases in the correct FA supplementation group, irrespective of the presence of the main NTD risk factors. The effect on NTD subtype distribution was only seen when FA supplementation was started before conception. We conclude that FA not only prevents the occurrence of a significant proportion of NTDs, but might also decrease the severity of NTDs, as long as supplementation is started before conception.

  4. Ag/Au/Pt trimetallic nanoparticles with defects: preparation, characterization, and electrocatalytic activity in methanol oxidation

    Science.gov (United States)

    Thongthai, Kontee; Pakawanit, Phakkhananan; Chanlek, Narong; Kim, Jun-Hyun; Ananta, Supon; Srisombat, Laongnuan

    2017-09-01

    Two series of Ag x /Au/Pt y trimetallic nanoparticles (Ag x Au1Pt2 with x ranging from 1-5 and Ag4Au1Pt y with y ranging from 1-3) were prepared by a sequential chemical reduction method that involved the deposition of Pt on preformed Ag/Au core-shell particles by systematically controlling the amount of Ag, Au, and Pt metal precursor solutions. The structural changes (the diameters and increased surface roughness from the defective features) and absorption patterns (the significant reduction of the peak intensities) of the nanoparticles examined with TEM and UV-vis spectroscopy indicated the selective incorporation of Pt on the Ag/Au nanoparticles regardless of their compositions. In addition, a combination of WDX, XRD, and XPS analyses quantitatively and qualitatively confirmed the successful formation of the Ag x Au1Pt2 and Ag4Au1Pt y trimetallic nanoparticles. Subsequently, these series of nanoparticles were deposited on multi-wall carbon nanotubes (MWCNTs) to evaluate their electrocatalytic property in the methanol oxidation reaction (MOR) as a function of their metal compositions. The results showed that the electrocatalytic activities of all Ag4/Au1/Pt y systems were higher than those of typical Pt on the MWCNTs. In particular, the Ag4Au1Pt2 nanoparticles exhibited the highest electrocatalytic property for the MOR, suggesting the importance of the proper combination of metal constituents and structures to regulate the activity in electrocatalytic systems.

  5. Control of morphology and defect density in zinc oxide for improved dye-sensitized solar cells.

    Science.gov (United States)

    Kim, Seul Ah; Abbas, Muhammad Awais; Lee, Lanlee; Kang, Byungwuk; Kim, Hahkjoon; Bang, Jin Ho

    2016-11-09

    While zinc oxide (ZnO) with a mesoporous network has long been explored for adsorption of dyes and as an electron-transporting medium in dye-sensitized solar cells (DSSCs), the performance of ZnO-based DSSCs remains unsatisfactory. Despite the importance of understanding the surface characteristics of ZnO in DSSC applications, most of the studies relevant to ZnO-based DSSCs are focused on the synthesis of unique nanostructures of ZnO. In this study, we not only introduce a novel disk-shaped ZnO nanostructure, but also provide insight into the distinctive surface properties of ZnO and its influence on DSSC performance. When utilized in DSSCs, the mesoporous ZnO nanodisk yields 60% better power conversion efficiency (PCE) compared to commercial ZnO nanoparticles, which is attributed to less surface and bulk trap densities as concluded by an in-depth open-circuit voltage decay (OCVD) analysis and electrochemical impedance spectroscopy (EIS). Another aspect that contributes to the higher PCE is the better connectivity of primary particles that join together to form secondary disk-shaped particles. Furthermore, a 40% improvement in the PCE was observed by coating the mesoporous ZnO nanodisk with TiO2, which results from the passivation of the surface defects that aid in suppressing the interfacial charge recombination.

  6. Pd oxides/hydrous oxides as highly efficient catalyst for formic acid electrooxidation

    Science.gov (United States)

    Yan, Liang; Yao, Shikui; Chang, Jinfa; Liu, Changpeng; Xing, Wei

    2014-03-01

    A novel Pd-based catalyst for formic acid electrooxidation (FAEO) was prepared by annealing commercial Pd/C catalyst under the O2 atmosphere at 100 °C, which exhibits excellent catalytic activity and stability for FAEO due to introduction of Pd oxides/hydrous oxides (POHOs). The catalytic activity of the as-prepared catalyst towards FAEO is 1.86 times of the commercial Pd/C catalyst in 0.5 M H2SO4 + 0.5 M HCOOH solution. Chronoamperometric curves show obvious improvement of the as-prepared catalyst electrocatalytic stability for FAEO. It is confirmed that POHOs can provide the required oxygen species for intermediate CO oxidation during the oxidation process of formic acid.

  7. Surface oxide growth on platinum electrode in aqueous trifluoromethanesulfonic acid

    Science.gov (United States)

    Furuya, Yoshihisa; Mashio, Tetsuya; Ohma, Atsushi; Dale, Nilesh; Oshihara, Kenzo; Jerkiewicz, Gregory

    2014-10-01

    Platinum in the form of nanoparticles is the key and most expensive component of polymer electrolyte membrane fuel cells, while trifluoromethanesulfonic acid (CF3SO3H) is the smallest fluorinated sulfonic acid. Nafion, which acts as both electrolyte and separator in fuel cells, contains -CF2SO3H groups. Consequently, research on the electrochemical behaviour of Pt in aqueous CF3SO3H solutions creates important background knowledge that can benefit fuel cell development. In this contribution, Pt electro-oxidation is studied in 0.1 M aqueous CF3SO3H as a function of the polarization potential (Ep, 1.10 ≤ Ep ≤ 1.50 V), polarization time (tp, 100 ≤ tp ≤ 104 s), and temperature (T, 278 ≤ T ≤ 333 K). The critical thicknesses (X1), which determines the applicability of oxide growth theories, is determined and related to the oxide thickness (dox). Because X1 > dox for the entire range of Ep, tp, and T values, the formation of Pt surface oxide follows the interfacial place-exchange or the metal cation escape mechanism. The mechanism of Pt electro-oxidation is revised and expanded by taking into account possible interactions of cations, anions, and water molecules with Pt. A modified kinetic equation for the interfacial place exchange is proposed. The application of the interfacial place-exchange and metal cation escape mechanisms leads to an estimation of the Ptδ+-Oδ- surface dipole (μPtO), and the potential drop (Vox) and electric field (Eox) within the oxide. The Pt-anion interactions affect the oxidation kinetics by indirectly influencing the electric field within the double layer and the surface oxide.

  8. Hydrophilic Graphene Preparation from Gallic Acid Modified Graphene Oxide in Magnesium Self-Propagating High Temperature Synthesis Process

    Science.gov (United States)

    Cao, Lei; Li, Zhenhuan; Su, Kunmei; Cheng, Bowen

    2016-10-01

    Hydrophilic graphene sheets were synthesized from a mixture of magnesium and gallic acid (GA) modified graphene oxide (GO) in a self-propagating high-temperature synthesis (SHS) process, and hydrophilic graphene sheets displayed the higher C/O ratio (16.36), outstanding conductivity (~88900 S/m) and excellent water-solubility. GO sheets were connected together by GA, and GA was captured to darn GO structure defects through the formation of hydrogen bonds and ester bonds. In SHS process, the most oxygen ions of GO reacted with magnesium to prevent the escape of carbon dioxide and carbon monoxide to from the structure defects associated with vacancies, and GA could take place the high-temperature carbonization, during which a large-area graphene sheets formed with a part of the structure defects being repaired. When only GO was reduced by magnesium in SHS process, and the reduced GO (rGO) exhibited the smaller sheets, the lower C/O ratio (15.26), the weaker conductivity (4200 S/m) and the poor water-solubility because rGO inevitably left behind carbon vacancies and topological defects. Therefore, the larger sheet, less edge defects and free structure defects associated with vacancies play a key role for graphene sheets good dispersion in water.

  9. Hydrophilic Graphene Preparation from Gallic Acid Modified Graphene Oxide in Magnesium Self-Propagating High Temperature Synthesis Process

    Science.gov (United States)

    Cao, Lei; Li, Zhenhuan; Su, Kunmei; Cheng, Bowen

    2016-01-01

    Hydrophilic graphene sheets were synthesized from a mixture of magnesium and gallic acid (GA) modified graphene oxide (GO) in a self-propagating high-temperature synthesis (SHS) process, and hydrophilic graphene sheets displayed the higher C/O ratio (16.36), outstanding conductivity (~88900 S/m) and excellent water-solubility. GO sheets were connected together by GA, and GA was captured to darn GO structure defects through the formation of hydrogen bonds and ester bonds. In SHS process, the most oxygen ions of GO reacted with magnesium to prevent the escape of carbon dioxide and carbon monoxide to from the structure defects associated with vacancies, and GA could take place the high-temperature carbonization, during which a large-area graphene sheets formed with a part of the structure defects being repaired. When only GO was reduced by magnesium in SHS process, and the reduced GO (rGO) exhibited the smaller sheets, the lower C/O ratio (15.26), the weaker conductivity (4200 S/m) and the poor water-solubility because rGO inevitably left behind carbon vacancies and topological defects. Therefore, the larger sheet, less edge defects and free structure defects associated with vacancies play a key role for graphene sheets good dispersion in water. PMID:27725757

  10. Effect of sulfonylureas on hepatic fatty acid oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Patel, T.B.

    1986-08-01

    In isolated rat livers perfused with oleic acid (0.1 mM), infusion of tolbutamide or glyburide decreased the rate of ketogenesis in a dose-dependent manner. The inhibition of fatty acid oxidation was maximal at 2.0 mM and 10 M concentrations of tolbutamide and glyburide, respectively. Neither tolbutamide nor glyburide inhibited ketogenesis in livers perfused with octanoate. The inhibition of hepatic ketogenesis by sulfonylureas was independent of perfusate oleic acid concentration. Additionally, in rat livers perfused with oleic acid in the presence of L-(-)-carnitine (10 mM), submaximal concentrations of tolbutamide and glyburide did not inhibit hepatic ketogenesis. Finally, glyburide infusion into livers perfused with (U- $C)oleic acid (0.1 mM) increased the rate of UC label incorporation into hepatic triglycerides by 2.5-fold. These data suggest that both tolbutamide and glyburide inhibit long-chain fatty acid oxidation by inhibition the key regulatory enzyme, carnitine palmitoyltransferase I, most probably by competing with L-(-)-carnitine.

  11. Ascorbate and dehydroascorbic acid as reliable biomarkers of oxidative stress

    DEFF Research Database (Denmark)

    Lykkesfeldt, Jens

    2007-01-01

    Lack of post-sampling stability of ascorbate and dehydroascorbic acid and failure to block their in vivo equilibrium have lowered their value as biomarkers of oxidative stress and limited the ability to further investigate their possible role in disease prevention. In the present paper, the analy......Lack of post-sampling stability of ascorbate and dehydroascorbic acid and failure to block their in vivo equilibrium have lowered their value as biomarkers of oxidative stress and limited the ability to further investigate their possible role in disease prevention. In the present paper......, the analytical reproducibility was tested by repeated analysis of plasma aliquots from one individual over four years. The plasma was subjected to acidic deproteinization with an equal volume of 10% meta-phosphoric acid containing 2 mM EDTA and analyzed for ascorbate and dehydroascorbic acid by high......-performance liquid chromatography with coulometric detection. In a parallel experiment, stability of human plasma samples treated as above and stored at -80°C for five years was tested in a cohort of 131 individuals. No degradation or shift in the equilibrium between ascorbate and dehydroascorbic acid was observed...

  12. Incidence of open neural tube defects in Nova Scotia after folic acid fortification

    Science.gov (United States)

    Persad, Vidia L.; Hof, Michiel; Dubé, Johanne M.; Zimmer, Pamela

    2002-01-01

    Background With the goal of preventing open neural tube defects (NTDs), recommendations for folic acid supplementation before conception were introduced in Canada in 1994, and by November 1998 Canadian grain products were being fortified with folic acid. We wished to determine whether the annual incidence of open NTDs in Nova Scotia, including those in stillbirths and terminated pregnancies, changed after the introduction of either folic acid supplementation or fortification. Methods For the 10-year period from Jan. 1, 1991, to Dec. 31, 2000, we retrospectively extracted the total number of births in Nova Scotia and the number of live births and stillbirths with open NTDs from the Nova Scotia Atlee Perinatal Database as well as the number of terminated pregnancies affected by NTDs from the Fetal Anomaly Database. We determined the total annual incidence of all open NTDs, and of the subgroups spina bifida and anencephaly, per 1000 births in the province during the periods before (1991–1994) and after (1995–1998) folic acid supplementation initiatives were begun but before folic acid fortification of grain products was implemented, and during the periods before (1991–1997) and after (1998–2000) fortification. Results In the period after supplementation initiatives were begun but before fortification was implemented, the incidence of open NTDs did not change significantly: the mean annual rate was 2.55 per 1000 births during 1991–1994 and 2.61 per 1000 births during 1995–1997 (relative risk [RR] 1.02, 95% confidence interval [CI] 0.77–1.35). After the fortification was implemented the incidence of open NTDs decreased by more than 50%: the mean annual rate was 2.58 per 1000 births during 1991–1997 and 1.17 per 1000 births during 1998–2000 (relative risk 0.46, 95% CI 0.32–0.66). Interpretation The recommendations for folic acid supplementation alone did not appear to succeed in reducing the incidence of open NTDs in Nova Scotia, whereas the

  13. Selective oxidation of propane to acrylic acid over mixed metal oxide catalysts

    Institute of Scientific and Technical Information of China (English)

    Wei Zheng; Zhenxing Yu; Ping Zhang; Yuhang Zhang; Hongying Fu; Xiaoli Zhang; Qiquan Sun; Xinguo Hu

    2008-01-01

    The effects of metal atomic ratio, water content, oxygen content, and calcination temperature on the catalytic perfor-mances of MoVTeNbO mixed oxide catalyst system for the selective oxidation of propane to acrylic acid have been investigated and discussed. Among the catalysts studied, it was found that the MoVTeNbO catalyst calcined at a temperature of 600 ℃ showed the best performance in terms of propane conversion and selectivity for acrylic acid under an atmosphere of nitrogen. An effective MoVTeNbO oxide catalyst for propane selective oxidation to acrylic acid was obtained with a combination of a preferred metal atomic ratio (Mo1 V0.31Te0.23Nb0.12). The optimum reaction condition for the selective oxidation of propane was the molar ratio of C3H81 :O2 : H2O : N1 = 4.4 : 12.8 : 15.3 : 36.9. Under such conditions, the conversion of propane and the maximum yield of acrylic acid reached about 50% and 21%, respectively.

  14. Temperature effects on the nitric acid oxidation of industrial grade multiwalled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Nadia F., E-mail: nadia@fisica.ufc.br [Universidade Federal do Ceara, Departamento de Fisica (Brazil); Martinez, Diego Stefani T., E-mail: diegostefani.br@gmail.com; Paula, Amauri J., E-mail: amaurijp@gmail.com [Universidade Estadual de Campinas (UNICAMP), Laboratorio de Quimica do Estado Solido (LQES), Instituto de Quimica (Brazil); Silveira, Jose V. [Universidade Federal do Ceara, Departamento de Fisica (Brazil); Alves, Oswaldo L., E-mail: oalves@iqm.unicamp.br [Universidade Estadual de Campinas (UNICAMP), Laboratorio de Quimica do Estado Solido (LQES), Instituto de Quimica (Brazil); Souza Filho, Antonio G., E-mail: agsf@fisica.ufc.br [Universidade Federal do Ceara, Departamento de Fisica (Brazil)

    2013-07-15

    In this study, we report an oxidative treatment of multiwalled carbon nanotubes (MWCNTs) by using nitric acid at different temperatures (25-175 Degree-Sign C). The analyzed materials have diameters varying from 10 to 40 nm and majority lengths between 3 and 6 {mu}m. The characterization results obtained by different techniques (e.g., field emission scanning electron microscopy, thermogravimetric analysis, energy-filtered transmission electron microscopy, Braunauer, Emmet and Teller method, {zeta}-potential and confocal Raman spectroscopy) allowed us to access the effects of temperature treatment on the relevant physico-chemical properties of the MWCNTs samples studied in view of an integrated perspective to use these samples in a bio-toxicological context. Analytical microbalance measurements were used to access the purity of samples (metallic residue) after thermogravimetric analysis. Confocal Raman spectroscopy measurements were used to evaluate the density of structural defects created on the surface of the tubes due to the oxidation process by using 2D Raman image. Finally, we have demonstrated that temperature is an important parameter in the generation of oxidation debris (a byproduct which has not been properly taken into account in the literature) in the industrial grade MWCNTs studied after nitric acid purification and functionalization.

  15. Electrochemical degradation of clofibric acid in water by anodic oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Sires, Ignasi [Laboratori de Ciencia i Tecnologia Electroquimica de Materials, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain); Cabot, Pere Lluis [Laboratori de Ciencia i Tecnologia Electroquimica de Materials, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain); Centellas, Francesc [Laboratori de Ciencia i Tecnologia Electroquimica de Materials, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain); Garrido, Jose Antonio [Laboratori de Ciencia i Tecnologia Electroquimica de Materials, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain); Rodriguez, Rosa Maria [Laboratori de Ciencia i Tecnologia Electroquimica de Materials, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain); Arias, Conchita [Laboratori de Ciencia i Tecnologia Electroquimica de Materials, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain); Brillas, Enric [Laboratori de Ciencia i Tecnologia Electroquimica de Materials, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain)]. E-mail: brillas@ub.edu

    2006-10-05

    Aqueous solutions containing the metabolite clofibric acid (2-(4-chlorophenoxy)-2-methylpropionic acid) up to close to saturation in the pH range 2.0-12.0 have been degraded by anodic oxidation with Pt and boron-doped diamond (BDD) as anodes. The use of BDD leads to total mineralization in all media due to the efficient production of oxidant hydroxyl radical ({center_dot}OH). This procedure is then viable for the treatment of wastewaters containing this compound. The effect of pH, apparent current density, temperature and metabolite concentration on the degradation rate, consumed specific charge and mineralization current efficiency has been investigated. Comparative treatment with Pt yields poor decontamination with complete release of stable chloride ion. When BDD is used, this ion is oxidized to Cl{sub 2}. Clofibric acid is more rapidly destroyed on Pt than on BDD, indicating that it is more strongly adsorbed on the Pt surface enhancing its reaction with {center_dot}OH. Its decay kinetics always follows a pseudo-first-order reaction and the rate constant for each anode increases with increasing apparent current density, being practically independent of pH and metabolite concentration. Aromatic products such as 4-chlorophenol, 4-chlorocatechol, 4-chlororesorcinol, hydroquinone, p-benzoquinone and 1,2,4-benzenetriol are detected by gas chromatography-mass spectrometry (GC-MS) and reversed-phase chromatography. Tartronic, maleic, fumaric, formic, 2-hydroxyisobutyric, pyruvic and oxalic acids are identified as generated carboxylic acids by ion-exclusion chromatography. These acids remain stable in solution using Pt, but they are completely converted into CO{sub 2} with BDD. A reaction pathway for clofibric acid degradation involving all these intermediates is proposed.

  16. Hepatic Fatty Acid Oxidation Restrains Systemic Catabolism during Starvation

    Directory of Open Access Journals (Sweden)

    Jieun Lee

    2016-06-01

    Full Text Available The liver is critical for maintaining systemic energy balance during starvation. To understand the role of hepatic fatty acid β-oxidation on this process, we generated mice with a liver-specific knockout of carnitine palmitoyltransferase 2 (Cpt2L−/−, an obligate step in mitochondrial long-chain fatty acid β-oxidation. Fasting induced hepatic steatosis and serum dyslipidemia with an absence of circulating ketones, while blood glucose remained normal. Systemic energy homeostasis was largely maintained in fasting Cpt2L−/− mice by adaptations in hepatic and systemic oxidative gene expression mediated in part by Pparα target genes including procatabolic hepatokines Fgf21, Gdf15, and Igfbp1. Feeding a ketogenic diet to Cpt2L−/− mice resulted in severe hepatomegaly, liver damage, and death with a complete absence of adipose triglyceride stores. These data show that hepatic fatty acid oxidation is not required for survival during acute food deprivation but essential for constraining adipocyte lipolysis and regulating systemic catabolism when glucose is limiting.

  17. Defective branched chain amino acid catabolism contributes to cardiac dysfunction and remodeling following myocardial infarction.

    Science.gov (United States)

    Wang, Wei; Zhang, Fuyang; Xia, Yunlong; Zhao, Shihao; Yan, Wenjun; Wang, Helin; Lee, Yan; Li, Congye; Zhang, Ling; Lian, Kun; Gao, Erhe; Cheng, Hexiang; Tao, Ling

    2016-11-01

    Cardiac metabolic remodeling is a central event during heart failure (HF) development following myocardial infarction (MI). It is well known that myocardial glucose and fatty acid dysmetabolism contribute to post-MI cardiac dysfunction and remodeling. However, the role of amino acid metabolism in post-MI HF remains elusive. Branched chain amino acids (BCAAs) are an important group of essential amino acids and function as crucial nutrient signaling in mammalian animals. The present study aimed to determine the role of cardiac BCAA metabolism in post-MI HF progression. Utilizing coronary artery ligation-induced murine MI models, we found that myocardial BCAA catabolism was significantly impaired in response to permanent MI, therefore leading to an obvious elevation of myocardial BCAA abundance. In MI-operated mice, oral BCAA administration further increased cardiac BCAA levels, activated the mammalian target of rapamycin (mTOR) signaling, and exacerbated cardiac dysfunction and remodeling. These data demonstrate that BCAAs act as a direct contributor to post-MI cardiac pathologies. Furthermore, these BCAA-mediated deleterious effects were improved by rapamycin cotreatment, revealing an indispensable role of mTOR in BCAA-mediated adverse effects on cardiac function/structure post-MI. Of note, pharmacological inhibition of branched chain ketoacid dehydrogenase kinase (BDK), a negative regulator of myocardial BCAA catabolism, significantly improved cardiac BCAA catabolic disorders, reduced myocardial BCAA levels, and ameliorated post-MI cardiac dysfunction and remodeling. In conclusion, our data provide the evidence that impaired cardiac BCAA catabolism directly contributes to post-MI cardiac dysfunction and remodeling. Moreover, improving cardiac BCAA catabolic defects may be a promising therapeutic strategy against post-MI HF.

  18. DLTS study of annihilation of oxidation induced deep-level defects in Ni/SiO2/-Si MOS structures

    Indian Academy of Sciences (India)

    N Shashank; Sanjeev K Gupta; K V Madhu; J Akhtar; R Damle

    2011-12-01

    This paper describes the fabrication of MOS capacitor and DLTS study of annihilation of deeplevel defects upon thermal annealing. Ni/SiO2/-Si MOS structures fabricated on -type Si wafers were investigated for process-induced deep-level defects. The deep-level traps in Si substrates induced during the processing of Ni/SiO2/-Si have been investigated using deep-level transient spectroscopy (DLTS). A characteristic deep-level defect at C = 0.49 eV which was introduced during high-temperature thermal oxidation process was detected. The trap position was found to shift to different energy levels (C = 0.43, 0.46 and 0.34 eV) during thermal annealing process. The deep-level trap completely anneals at 350°C. Significant reduction in trap density with an increase in recombination life time and substrate doping concentration as a function of isochronal annealing were observed.

  19. Type 2 diabetes mellitus induces congenital heart defects in murine embryos by increasing oxidative stress, endoplasmic reticulum stress, and apoptosis

    Science.gov (United States)

    Wu, Yanqing; Reece, E. Albert; Zhong, Jianxiang; Dong, Daoyin; Shen, Wei-Bin; Harman, Christopher R.; Yang, Peixin

    2017-01-01

    BACKGROUND Maternal type 1 and 2 diabetes mellitus are strongly associated with high rates of severe structural birth defects, including congenital heart defects. Studies in type 1 diabetic embryopathy animal models have demonstrated that cellular stress-induced apoptosis mediates the teratogenicity of maternal diabetes leading to congenital heart defect formation. However, the mechanisms underlying maternal type 2 diabetes mellitus–induced congenital heart defects remain largely unknown. OBJECTIVE We aim to determine whether oxidative stress, endoplasmic reticulum stress, and excessive apoptosis are the intracellular molecular mechanisms underlying maternal type 2 diabetes mellitus–induced congenital heart defects. STUDY DESIGN A mouse model of maternal type 2 diabetes mellitus was established by feeding female mice a high-fat diet (60% fat). After 15 weeks on the high-fat diet, the mice showed characteristics of maternal type 2 diabetes mellitus. Control dams were either fed a normal diet (10% fat) or the high-fat diet during pregnancy only. Female mice from the high-fat diet group and the 2 control groups were mated with male mice that were fed a normal diet. At E12.5, embryonic hearts were harvested to determine the levels of lipid peroxides and superoxide, endoplasmic reticulum stress markers, cleaved caspase 3 and 8, and apoptosis. E17.5 embryonic hearts were harvested for the detection of congenital heart defect formation using India ink vessel patterning and histological examination. RESULTS Maternal type 2 diabetes mellitus significantly induced ventricular septal defects and persistent truncus arteriosus in the developing heart, along with increasing oxidative stress markers, including superoxide and lipid peroxidation; endoplasmic reticulum stress markers, including protein levels of phosphorylated-protein kinase RNA-like endoplasmic reticulum kinase, phosphorylated-IRE1α, phosphorylated-eIF2α, C/EBP homologous protein, and binding immunoglobulin

  20. Folate deficiency-induced oxidative stress contributes to neuropathy in young and aged zebrafish--implication in neural tube defects and Alzheimer's diseases.

    Science.gov (United States)

    Kao, Tseng-Ting; Chu, Chia-Yi; Lee, Gang-Hui; Hsiao, Tsun-Hsien; Cheng, Nai-Wei; Chang, Nan-Shan; Chen, Bing-Hung; Fu, Tzu-Fun

    2014-11-01

    Folate is a nutrient essential for the development, function and regeneration of nervous systems. Folate deficiency has been linked to many neurological disorders including neural tube defects in fetus and Alzheimer's diseases in the elderly. However, the etiology underlying these folate deficiency-associated diseases is not completely understood. In this study, zebrafish transgenic lines with timing and duration-controllable folate deficiency were developed by ectopically overexpressing a recombinant EGFP-γ-glutamyl hydrolase (γGH). Impeded neural crest cell migration was observed in the transgenic embryos when folate deficiency was induced in early stages, leading to defective neural tube closure and hematopoiesis. Adding reduced folate or N-acetylcysteine reversed the phenotypic anomalies, supporting the causal link between the increased oxidative stress and the folate deficiency-induced abnormalities. When folate deficiency was induced in aged fish accumulation of beta-amyloid and phosphorylated Tau protein were found in the fish brain cryo-sections. Increased autophagy and accumulation of acidic autolysosome were apparent in folate deficient neuroblastoma cells, which were reversed by reduced folate or N-acetylcysteine supplementation. Decreased expression of cathepsin B, a lysosomal protease, was also observed in cells and tissue with folate deficiency. We concluded that folate deficiency-induced oxidative stress contributed to the folate deficiency-associated neuropathogenesis in both early and late stages of life.

  1. Hypotrophy of conduit artery walls of the offspring of nitric oxide-defective rats

    Directory of Open Access Journals (Sweden)

    Kristek F.

    2004-01-01

    Full Text Available The objective of the present study was to investigate the structure of the arterial walls of the offspring stemming from nitric oxide (NO-defective hypertensive parents. The parents were treated with N G-nitro-L-arginine methyl ester (40 mg kg-1 day-1 for 5 weeks. Blood pressure was measured noninvasively in six 30-day-old rats and nine age-matched controls. The cardiovascular system was perfused with glutaraldehyde at 120 mmHg. The thoracic aorta and carotid artery were processed for electron microscopy, and geometry was determined by light microscopy. Endothelial cells, smooth muscle cells (SMC and extracellular matrix (ECM were determined by the point counting method in electron micrographs of the carotid artery. The blood pressure of experimental offspring was 150.0 ± 2.3 vs 104.6 ± 2.1 mmHg (P < 0.01 for the controls and their heart/body weight ratio of 3.9 ± 0.1 vs 4.4 ± 0.2 (P < 0.05 for the controls indicated cardiac hypotrophy. The wall thickness (tunica intima and media of the thoracic aorta and carotid artery of experimental offspring was decreased to 78.9% (P < 0.01 and 83.8% (P < 0.01, respectively, compared to controls, as confirmed by a respective cross-sectional area of 85.3% (P < 0.01 and 84.1% (P < 0.01. The wall thickness/inner diameter ratio was reduced to 75% (P < 0.01 in the thoracic artery and to 81.5% (P < 0.01 in the carotid artery. No change in endothelial cell volume density or ECM was observed in the tunica intima of the carotid artery, and SMC volume density was lower in the tunica media (37.6 ± 0.9 vs 44.7 ± 1.1% for controls, P < 0.01, indicating compromised SMC development. Interference with arginine metabolism, a decrease in NO, and other factors are possible mechanisms underlying the structural alterations of the cardiovascular system of offspring from NO-defective hypertensive rats.

  2. Formic acid oxidation at platinum-bismuth catalysts

    Directory of Open Access Journals (Sweden)

    Popović Ksenija Đ.

    2015-01-01

    Full Text Available The field of heterogeneous catalysis, specifically catalysis on bimetallic surfaces, has seen many advances over the past few decades. Bimetallic catalysts, which often show electronic and chemical properties that are distinct from those of their parent metals, offer the opportunity to obtain new catalysts with enhanced selectivity, activity, and stability. The oxidation of formic acid is of permanent interest as a model reaction for the mechanistic understanding of the electrooxidation of small organic molecules and because of its technical relevance for fuel cell applications. Platinum is one of the most commonly used catalysts for this reaction, despite the fact that it shows a few significant disadvantages: high cost and extreme susceptibility to poisoning by CO. To solve this problem, several approaches have been used, but generally, they all consist in the modification of platinum with a second element. Especially, bismuth has received significant attention as Pt modifier. According to the results presented in this survey dealing with the effects influencing the formic acid oxidation it was found that two types of Pt-Bi bimetallic catalysts (bulk and low loading deposits on GC showed superior catalytic activity in terms of the lower onset potential and oxidation current density, as well as exceptional stability compared to Pt. The findings in this report are important for the understanding of mechanism of formic acid electrooxidation on a bulk alloy and decorated surface, for the development of advanced anode catalysts for direct formic acid fuel cells, as well as for the synthesis of novel low-loading bimetallic catalysts. The use of bimetallic compounds as the anode catalysts is an effective solution to overcoming the problems of the formic acid oxidation current stability for long term applications. In the future, the tolerance of both CO poisoning and electrochemical leaching should be considered as the key factors in the development

  3. Influence of defect luminescence and structural modification on the electrical properties of Magnesium Doped Zinc Oxide Nanorods

    Science.gov (United States)

    Santoshkumar, B.; Biswas, Amrita; Kalyanaraman, S.; Thangavel, R.; Udayabhanu, G.; Annadurai, G.; Velumani, S.

    2017-06-01

    Magnesium doped zinc oxide nanorod arrays on zinc oxide seed layers were grown by hydrothermal method. X-ray diffraction (XRD) patterns revealed the growth orientation along the preferential (002) direction. The hexagonal morphology was revealed from the field emission scanning electron microscope (FESEM) images. The elemental composition of the samples was confirmed by energy dispersive x-ray analysis spectra (EDS) and mapping dots. Carrier concentration, resistivity and mobility of the samples were obtained by Hall measurements. I-V characteristic curve confirmed the increase in resistivity upon doping. Photoluminescence (PL) spectra exposed the characteristic of UV emission along with defect mediated visible emission in the samples. Electrochemical impedance spectroscopy and cyclic voltammetry were undertaken to study the charge transport property. Owing to the change in the structural parameters and defect concentration the electrical properties of the doped samples were altered.

  4. Significant enhancement of formic acid oxidation using rhodium nanostructures.

    Science.gov (United States)

    Balan, Beena K; Sathe, Bhaskar R

    2012-12-01

    The electrocatalytic activity of as-synthesized shape selective Rh nanostructures has been demonstrated using cyclic voltammetry, revealing unique shape-dependant performance towards HCOOH oxidation. Interestingly, the enhancement factor (R) for different shapes of Rh with respect to that of commercial Rh towards formic acid oxidation ranges up to 20,000% for cubes as compared to 17,500% for pyramids and 11,000% for hexagons respectively. Mechanistic pathway for comparatively better sensitivity of cubes as compared to other shapes has been correlated with the results of X-ray diffraction.

  5. Efficiency of mitochondrially targeted gallic acid in reducing brain mitochondrial oxidative damage.

    Science.gov (United States)

    Parihar, P; Jat, D; Ghafourifar, P; Parihar, M S

    2014-07-03

    Oxidative stress is associated with mitochondrial impairments. Supplying mitochondria with potent antioxidants can reduce oxidative stress—induced mitochondrial impairment. Gallic acid can be used to reduce oxidative burden in mitochondria. In order to increase the bioavailability of gallic acid inside the mitochondria we synthesized mitochondrially targeted gallic acid and explored its preventive effects against sodium nitroprusside induced oxidative stress in isolated mitochondria. Our observations revealed an increase in oxidative stress,decrease in reduced glutathione in mitochondria and increase in the mitochondrial permeability pore transition due to sodium nitroprusside treatment. Pre—treatment of gallic acid and mitochondrially targeted gallic acid to sodium nitroprusside treated mitochondria not only significantly reduced the oxidative stress but also prevented mitochondrial permeability pore transition to a significant difference. Mitochondrially targeted gallic acid was found more effective in reducing oxidative stress and mitochondrial permeability pore transition than gallic acid. We conclude that mitochondrially targeted gallic acid can be used for preventing mitochondrial impairment caused by oxidative stress.

  6. Oxidative stability of Liposomes composed of docosahexaenoic acid-containing phospholipids

    DEFF Research Database (Denmark)

    Vikbjerg, Anders Falk; Andresen, Thomas Lars; Jørgensen, Kent

    2007-01-01

    Oxidative stability of liposomes made of (Docosahexaenoic acid) DHA-containing phosphatidylcholine (PC) was examined during preparation and storage. After preparation of the liposomes, the concentration of primary (conjugated dienes) and secondary oxidation products (Thiobarbituric acid...

  7. Kinetics and mechanism of the oxidation of some neutral and acidic -amino acids by tetrabutylammonium tribromide

    Indian Academy of Sciences (India)

    Raghvendra Shukla; Pradeep K Sharma; Kalyan K Banerji

    2004-03-01

    The oxidation of eleven amino acids by tetrabutylammonium tribromide (TBATB) in aqueous acetic acid results in the formation of the corresponding carbonyl compounds and ammonia. The reaction is first order with respect to TBATB. Michaelis-Menten type kinetics is observed with some of the amino acids while others exhibit second-order dependence. It failed to induce polymerization of acrylonitrile. The effect of solvent composition indicate that the rate of reaction increases with increase in the polarity of the medium. Addition of tetrabutylammonium chloride has no effect on the rate of oxidation. Addition of bromide ion causes decrease in the oxidation rate but only to a limiting value. The reaction is susceptible to both polar and steric effects of the substituents. A suitable mechanism has been proposed.

  8. Kinetics of Oxidation of 3-Benzoylpropionic Acid by N-Bromoacetamide in Aqueous Acetic Acid Medium

    Directory of Open Access Journals (Sweden)

    N. A. Mohamed Farook

    2011-01-01

    Full Text Available The kinetics of oxidation of 3-benzoylpropionic acid (KA with N-bromoacetamide (NBA have been studied potentiometrically in 50:50 (v/v aqueous acetic acid medium at 298 K The reaction was first order each with respect to [KA], [NBA] and [H+]. The main product of the oxidation is the corresponding carboxylic acid. The rate decreases with the addition of acetamide, one of the products of the reaction. Variation in ionic strength of the reaction medium has no significant effect on the rate of oxidation. But the rate of the reaction is enhanced by lowering the dielectric constant of the reaction medium. A mechanism consistent with observed results have been proposed and the related rate law was deduced.

  9. Bond energies in polyunsaturated acids and kinetics of co-oxidation of protiated and deuterated acids

    Science.gov (United States)

    Andrianova, Z. S.; Breslavskaya, N. N.; Pliss, E. M.; Buchachenko, A. L.

    2016-10-01

    A computational program specially designed to analyze co-oxidation of substances in mixtures is suggested. The rigorous kinetic scheme of 32 reactions describing co-oxidation of isotope differing polyunsaturated fatty acids was computed to enlighten experimentally detected enormously large H/D isotope effects. The latter were shown to depend on the kinetic chain length and exhibit two extreme regimes of short and long chains which characterize isotope effects on the initiation and propagation chain reactions of hydrogen (deuterium) atom abstraction. No protective effect of deuterated polyunsaturated acids on the oxidation of protiated acids was detected. Protective effect of the deuterated compounds on the biologically important processes seems to be induced by the low yield of products formed in the chain termination reactions due to the low rate of initiation by deuterated compounds.

  10. Reversal of hyperactive Wnt signaling-dependent adipocyte defects by peptide boronic acids.

    Science.gov (United States)

    Zhang, Tianyi; Hsu, Fu-Ning; Xie, Xiao-Jun; Li, Xiao; Liu, Mengmeng; Gao, Xinsheng; Pei, Xun; Liao, Yang; Du, Wei; Ji, Jun-Yuan

    2017-08-21

    Deregulated Wnt signaling and altered lipid metabolism have been linked to obesity, diabetes, and various cancers, highlighting the importance of identifying inhibitors that can modulate Wnt signaling and aberrant lipid metabolism. We have established a Drosophila model with hyperactivated Wnt signaling caused by partial loss of axin, a key component of the Wnt cascade. The Axin mutant larvae are transparent and have severe adipocyte defects caused by up-regulation of β-catenin transcriptional activities. We demonstrate pharmacologic mitigation of these phenotypes in Axin mutants by identifying bortezomib and additional peptide boronic acids. We show that the suppressive effect of peptide boronic acids on hyperactive Wnt signaling is dependent on α-catenin; the rescue effect is completely abolished with the depletion of α-catenin in adipocytes. These results indicate that rather than targeting the canonical Wnt signaling pathway directly, pharmacologic modulation of β-catenin activity through α-catenin is a potentially attractive approach to attenuating Wnt signaling in vivo.

  11. Amino Acid and Peptide Immobilization on Oxidized Nanocellulose: Spectroscopic Characterization

    Directory of Open Access Journals (Sweden)

    Claude Daneault

    2012-06-01

    Full Text Available In this work, oxidized nanocellulose (ONC was synthesized and chemically coupled with amino acids and peptides using a two step coupling method at room temperature. First, ONC was activated by N-ethyl-N’-(3-dimethylaminopropyl carbodiimide hydrochloride, forming a stable active ester in the presence of N-hydroxysuccinimide. Second, the active ester was reacted with the amino group of the amino acid or peptide, forming an amide bond between ONC and the grafted molecule. Using this method, the intermolecular interaction of amino acids and peptides was avoided and uniform coupling of these molecules on ONC was achieved. The coupling reaction was very fast in mild conditions and without alteration of the polysaccharide. The coupling products (ONC-amino acids and ONC-peptides were characterized by transmission electron microscopy and by the absorption, emission, Fourier transform infrared spectroscopy (FTIR and X-ray photoelectron spectroscopy (XPS spectroscopic techniques.

  12. Microstructural characterization of oxide film formed on NiTi by anodization in acetic acid

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, F.T. [Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong)]. E-mail: apaftche@polyu.edu.hk; Shi, P. [Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong); Department of Materials and Chemical Engineering, Liaoning Institute of Technology, Jinzhou, Liaoning (China); Pang, G.K.H. [Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong); Wong, M.H. [Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong); Man, H.C. [Department of Industrial and Systems Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong)

    2007-07-12

    NiTi was galvanostatically anodized in acetic acid aiming at forming an anodic film for improving corrosion resistance. While the corrosion behavior of anodized NiTi in Hanks' solution was reported elsewhere [P. Shi, F.T. Cheng, H.C. Man, Mater. Lett., submitted for publication], the present work reports the microstructural characterization of the anodic film formed. Bright-field image of the sample cross-section captured by transmission electron microscopy (TEM) revealed an oxide film of about 20 nm thick, which was smooth and free of defects. The surface roughness R {sub a} of the film, determined by atomic force microscopy (AFM), was about 1.45 nm. Analysis by X-ray photoelectron spectroscopy (XPS) along the depth of the anodic film indicated that the oxidation state of Ti varied from +4 (corresponding to TiO{sub 2}) at the surface to lower oxidation states (corresponding to Ti suboxides) beneath. A small amount of Ni in the metallic and oxidized states was also present. The Ni/Ti atomic ratio was about 0.04 at the surface of the anodic film, which was much lower than the corresponding value of 0.30 for the mechanically polished samples. Selected-area diffraction (SAD) patterns and high-resolution TEM image of the anodic film showed that the film was amorphous.

  13. Downscaled anodic oxidation process for aluminium in oxalic acid

    Science.gov (United States)

    Sieber, M.; Morgenstern, R.; Kuhn, D.; Hackert-Oschätzchen, M.; Schubert, A.; Lampke, T.

    2017-03-01

    The increasing multi-functionality of parts and assemblies in several fields of engineering demands, amongst others, highly functionalised surfaces. For the different applications, on the one hand, there is a need to scale up surface modification processes originating in the nano- and micro-scale. On the other hand, conventional macro-scale surface refinement methods offer a huge potential for application in the said nano- and micro-scale. The anodic oxidation process, which is established especially for aluminium and its alloys, allows the formation of oxide ceramic layers on the surface. The build-up of an oxide ceramic coating comes along with altered chemical, tribological and electrical surface properties. As a basis for further investigations regarding the use of the anodic oxidation process for micro-scale-manufacturing, the scale effects of oxalic acid anodising on commercially pure aluminium as well as on the AlZn5.5MgCu alloy are addressed in the present work. The focus is on the amount of oxide formed during a potentiostatic process in relation to the exchanged amount of charge. Further, the hardness of the coating as an integral measure to assess the porous oxide structure is approached by nano-indentation technique.

  14. Oxidized fatty acids as inter-kingdom signaling molecules.

    Science.gov (United States)

    Pohl, Carolina H; Kock, Johan L F

    2014-01-20

    Oxylipins or oxidized fatty acids are a group of molecules found to play a role in signaling in many different cell types. These fatty acid derivatives have ancient evolutionary origins as signaling molecules and are ideal candidates for inter-kingdom communication. This review discusses examples of the ability of organisms from different kingdoms to "listen" and respond to oxylipin signals during interactions. The interactions that will be looked at are signaling between animals and plants; between animals and fungi; between animals and bacteria and between plants and fungi. This will aid in understanding these interactions, which often have implications in ecology, agriculture as well as human and animal health.

  15. Enhanced formic acid oxidation on Cu-Pd nanoparticles

    Science.gov (United States)

    Dai, Lin; Zou, Shouzhong

    Developing catalysts with high activity and high resistance to surface poisoning remains a challenge in direct formic acid fuel cell research. In this work, copper-palladium nanoparticles were formed through a galvanic replacement process. After electrochemically selective dissolution of surface Cu, Pd-enriched Cu-Pd nanoparticles were formed. These particles exhibit much higher formic acid oxidation activities than that on pure Pd nanoparticles, and they are much more resistant to the surface poisoning. Possible mechanisms of catalytic activity enhancement are briefly discussed.

  16. Synthesis of docosahexaenoic acid from eicosapentaenoic acid in retina neurons protects photoreceptors from oxidative stress.

    Science.gov (United States)

    Simón, María Victoria; Agnolazza, Daniela L; German, Olga Lorena; Garelli, Andrés; Politi, Luis E; Agbaga, Martin-Paul; Anderson, Robert E; Rotstein, Nora P

    2016-03-01

    Oxidative stress is involved in activating photoreceptor death in several retinal degenerations. Docosahexaenoic acid (DHA), the major polyunsaturated fatty acid in the retina, protects cultured retina photoreceptors from apoptosis induced by oxidative stress and promotes photoreceptor differentiation. Here, we investigated whether eicosapentaenoic acid (EPA), a metabolic precursor to DHA, had similar effects and whether retinal neurons could metabolize EPA to DHA. Adding EPA to rat retina neuronal cultures increased opsin expression and protected photoreceptors from apoptosis induced by the oxidants paraquat and hydrogen peroxide (H2 O2 ). Palmitic, oleic, and arachidonic acids had no protective effect, showing the specificity for DHA. We found that EPA supplementation significantly increased DHA percentage in retinal neurons, but not EPA percentage. Photoreceptors and glial cells expressed Δ6 desaturase (FADS2), which introduces the last double bond in DHA biosynthetic pathway. Pre-treatment of neuronal cultures with CP-24879 hydrochloride, a Δ5/Δ6 desaturase inhibitor, prevented EPA-induced increase in DHA percentage and completely blocked EPA protection and its effect on photoreceptor differentiation. These results suggest that EPA promoted photoreceptor differentiation and rescued photoreceptors from oxidative stress-induced apoptosis through its elongation and desaturation to DHA. Our data show, for the first time, that isolated retinal neurons can synthesize DHA in culture. Docosahexaenoic acid (DHA), the major polyunsaturated fatty acid in retina photoreceptors, and its precursor, eicosapentaenoic acid (EPA) have multiple beneficial effects. Here, we show that retina neurons in vitro express the desaturase FADS2 and can synthesize DHA from EPA. Moreover, addition of EPA to these cultures protects photoreceptors from oxidative stress and promotes their differentiation through its metabolization to DHA.

  17. Will Increasing Folic Acid in Fortified Grain Products Further Reduce Neural Tube Defects without Causing Harm?: Consideration of the Evidence

    Science.gov (United States)

    Will Increasing Folic Acid in Fortified Grain Products Further Reduce Neural Tube Defects without Causing Harm?: Consideration of the Evidence. In the January issue of this journal, Johnston (1) includes our group’s recent analysis of data from the 1999-2002 National Health and Nutrition Examination...

  18. Not all cases of neural-tube defect can be prevented by increasing the intake of folic acid

    Science.gov (United States)

    The objective of this study was to evaluate the beneficial effects of different levels of folic acid administration on the prevalence of neural tube defects, with a concurrent assessment of other potential benefits or adverse effects. The evaluation was based on a systematic review of the published ...

  19. Craniosynostosis and Multiple Skeletal Anomalies in Humans and Zebrafish Result from a Defect in the Localized Degradation of Retinoic Acid

    NARCIS (Netherlands)

    Laue, Kathrin; Pogoda, Hans-Martin; Daniel, Philip B.; van Haeringen, Arie; Alanay, Yasemin; von Ameln, Simon; Rachwalski, Martin; Morgan, Tim; Gray, Mary J.; Breuning, Martijn H.; Sawyer, Gregory M.; Sutherland-Smith, Andrew J.; Nikkels, Peter G.; Kubisch, Christian; Bloch, Wilhelm; Wollnik, Bernd; Hammerschmidt, Matthias; Robertson, Stephen P.

    2011-01-01

    Excess exogenous retinoic acid (RA) has been well documented to have teratogenic effects in the limb and craniofacial skeleton. Malformations that have been observed in this context include craniosynostosis, a common developmental defect of the skull that occurs in 1 in 2500 individuals and results

  20. Prevalence of neural tube defects and folic acid knowledge and consumption--Puerto Rico, 1996-2006.

    Science.gov (United States)

    2008-01-11

    Birth defects are one of the leading causes of infant mortality in both the mainland United States and Puerto Rico. Neural tube defects (NTDs) are serious birth defects of the spine and brain; two of the most common NTDs are spina bifida and anencephaly. In the United States, NTD prevalence is higher among Hispanic women than among non-Hispanic white or non-Hispanic black women. In Puerto Rico, where most residents are Hispanic, the prevalence of NTDs (8.68 per 10,000 live births) is higher than in the mainland United States (5.59). Consumption of folic acid before and during early pregnancy can prevent NTDs. To assess trends in NTD prevalence and prevalence of knowledge and consumption of folic acid supplements in Puerto Rico, data were analyzed from the Birth Defects Surveillance System (BDSS) for 1996-2005 and the Behavioral Risk Factor Surveillance System (BRFSS) for 1997-2006. This report describes the results of those analyses, which indicated that prevalence of folic acid knowledge and consumption among women of childbearing age increased from 1997 to 2003 but decreased from 2003 to 2006. During similar periods, NTD prevalence declined from 1996 to 2003 but did not change significantly from 2003 to 2005. To resume the decline in prevalence of NTDs, additional measures might be needed to increase folic acid supplement use among Puerto Rican women of childbearing age.

  1. Evaluation of effectiveness of hyaluronic acid in combination with bioresorbable membrane (poly lactic acid-poly glycolic acid) for the treatment of infrabony defects in humans: A clinical and radiographic study

    OpenAIRE

    Bhumika Sehdev; Manohar Laxmanrao Bhongade; Kiran Kumar Ganji

    2016-01-01

    Background: The combination of biomaterials, bone graft substitutes along with guided tissue regeneration (GTR) has been shown to be an effective modality of periodontal regenerative therapy for infrabony defects. Therefore, the present randomized controlled clinical study was undertaken to evaluate the effectiveness of hyaluronic acid (HA) in combination with bioresorbable membrane for the treatment of human infrabony defects. Materials and Methods: Twenty four infrabony defects in 20 system...

  2. Reduced Graphene Oxides: Influence of the Reduction Method on the Electrocatalytic Effect towards Nucleic Acid Oxidation

    Science.gov (United States)

    Báez, Daniela F.; Pardo, Helena; Laborda, Ignacio; Marco, José F.; Yáñez, Claudia; Bollo, Soledad

    2017-01-01

    For the first time a critical analysis of the influence that four different graphene oxide reduction methods have on the electrochemical properties of the resulting reduced graphene oxides (RGOs) is reported. Starting from the same graphene oxide, chemical (CRGO), hydrothermal (hTRGO), electrochemical (ERGO), and thermal (TRGO) reduced graphene oxide were produced. The materials were fully characterized and the topography and electroactivity of the resulting glassy carbon modified electrodes were also evaluated. An oligonucleotide molecule was used as a model of DNA electrochemical biosensing. The results allow for the conclusion that TRGO produced the RGOs with the best electrochemical performance for oligonucleotide electroanalysis. A clear shift in the guanine oxidation peak potential to lower values (~0.100 V) and an almost two-fold increase in the current intensity were observed compared with the other RGOs. The electrocatalytic effect has a multifactorial explanation because the TRGO was the material that presented a higher polydispersity and lower sheet size, thus exposing a larger quantity of defects to the electrode surface, which produces larger physical and electrochemical areas. PMID:28677654

  3. The role of functionally defective rare germline variants of sialic acid acetylesterase in autoimmune Addison's disease

    Science.gov (United States)

    Gan, Earn H; MacArthur, Katie; Mitchell, Anna L; Pearce, Simon H S

    2012-01-01

    Background Autoimmune Addison's disease (AAD) is a rare condition with a complex genetic basis. A panel of rare and functionally defective genetic variants in the sialic acid acetylesterase (SIAE) gene has recently been implicated in several common autoimmune conditions. We performed a case–control study to determine whether these rare variants are associated with a rarer condition, AAD. Method We analysed nine SIAE gene variants (W48X, M89V, C196F, C226G, R230W, T312M, Y349C, F404S and R479C) in a United Kingdom cohort of 378 AAD subjects and 387 healthy controls. All samples were genotyped using Sequenom iPlex chemistry to characterise primer extension products. Results A heterozygous rare allele at codon 312 (312*M) was found in one AAD patient (0.13%) but was not detected in the healthy controls. The commoner, functionally recessive variant at codon 89 (89*V) was found to be homozygous in two AAD patients but was only found in the heterozygous state in controls. Taking into account all nine alleles examined, 4/378 (1.06%) AAD patients and 1/387 (0.25%) healthy controls carried the defective SIAE alleles, with a calculated odds ratio of 4.13 (95% CI 0.44–97.45, two-tailed P value 0.212, NS). Conclusion We demonstrated the presence of 89*V homozygotes and the 312*M rare allele in the AAD cohort, but overall, our analysis does not support a role for rare variants in SIAE in the pathogenesis of AAD. However, the relatively small collection of AAD patients limits the power to exclude a small effect. PMID:23011869

  4. Free fatty acid oxidation in insulin resistance and obesity

    OpenAIRE

    Abel, E. Dale

    2010-01-01

    The growing worldwide epidemic of obesity and diabetes portends a significant increase in cardiovascular disease. Obesity is associated with insulin resistance, and there is growing evidence that these conditions independently increase the risk of heart failure. Changes in myocardial substrate utilization develop in obesity and insulin resistance, and are characterized by increased fatty acid oxidation and utilization, and decreased glucose utilization. This paper will review the evidence for...

  5. Glycolic acid production using ethylene glycol-oxidizing microorganisms.

    Science.gov (United States)

    Kataoka, M; Sasaki, M; Hidalgo, A R; Nakano, M; Shimizu, S

    2001-10-01

    Screening for microorganisms oxidizing ethylene glycol to glycolic acid was carried out. Among stock cultures, several yeasts and acetic acid bacteria showed high glycolic acid producing activity. Pichia naganishii AKU 4267 formed the highest concentration of glycolic acid, 35.3 g/l, from 10% (v/v) ethylene glycol (molar conversion yield, 26.0%). Among soil isolates, Rhodotorula sp. 3Pr-126, isolated using propylene glycol as a sole carbon source, formed the highest concentration of glycolic acid, 25.1 g/l, from 10% (v/v) ethylene glycol (molar conversion yield, 18.5%). Rhodotorula sp. 3Pr-126 showed higher activity toward 20% (v/v) ethylene glycol than P. naganishii AKU 4267. Optimization of the conditions for glycolic acid production was investigated using P. naganishii AKU 4267 and Rhodotorula sp. 3Pr-126. Under the optimized conditions, P. naganishii AKU 4267 and Rhodotorula sp. 3Pr-126 formed 105 and 110 g/l of glycolic acid (corrected molar conversion yields, 88.0 and 92.2%) during 120 h of reaction, respectively.

  6. Stearic acid protects primary cultured cortical neurons against oxidative stress

    Institute of Scientific and Technical Information of China (English)

    Ze-jian WANG; Cui-ling LIANG; Guang-mei LI; Cai-yi YU; Ming YIN

    2007-01-01

    Aim: To observe the effects of stearic acid against oxidative stress in primary cultured cortical neurons. Methods: Cortical neurons were exposed to glutamate,hydrogen peroxide (H202), or NaN3 insult in the presence or absence of stearic acid. Cell viability of cortical neurons was determined by MTT assay and LDH release. Endogenous antioxidant enzymes activity[superoxide dismutases (SOD),glutathione peroxidase (GSH-Px), and catalase (CAT)] and lipid peroxidation in cultured cortical neurons were evaluated using commercial kits. {3-[1(p-chloro-benzyl)-5-(isopropyl)-3-t-butylthiondol-2-yl]-2,2-dimethylpropanoic acid, Na}[MK886; 5 pmol/L; a noncompetitive inhibitor of proliferator-activated receptor(PPAR)α], bisphenol A diglycidyl ether (BADGE; 100 μmol/L; an antagonist of PPARγ), and cycloheximide (CHX; 30 μmol/L, an inhibitor of protein synthesis)were tested for their effects on the neuroprotection afforded by stearic acid.Western blotting was used to determine the PPARγ protein level in cortical neurons.Results: Stearic acid dose-dependently protected cortical neurons against glutamate or H202 injury and increased glutamate uptake in cultured neurons.This protection was concomitant to the inhibition of lipid peroxidation and to the promotion activity of Cu/Zn SOD and CAT in cultured cortical neurons. Its neuroprotective effects were completely blocked by BADGE and CHX. After incubation with H2O2 for 24 h, the expression of the PPARγ protein decreased significantly (P<0.05), and the inhibitory effect of H2O2 on the expression of PPARγ can be attenuated by stearic acid. Conclusion: Stearic acid can protect cortical neurons against oxidative stress by boosting the internal antioxidant enzymes.Its neuroprotective effect may be mainly mediated by the activation of PPARγ and new protein synthesis in cortical neurons.

  7. Effects of caffeic acid phenethyl ester on palatal mucosal defects and tooth extraction sockets

    Directory of Open Access Journals (Sweden)

    Günay A

    2014-10-01

    Full Text Available Ahmet Günay,1 Osman Fatih Arpağ,2 Serhat Atilgan,3 Ferhan Yaman,3 Yusuf Atalay,4 İzzet Acikan3 1Department of Periodontology, Faculty of Dentistry, Dicle University, Diyarbakir, Turkey; 2Department of Periodontology, Faculty of Dentistry, Mustafa Kemal University, Hatay, Turkey; 3Department of Maxillofacial Surgery, Faculty of Dentistry, Dicle University, Diyarbakir, Turkey; 4Department of Maxillofacial Surgery, Faculty of Dentistry, Kocatepe University, Afyon, Turkey Aim: The purpose of this study was to evaluate the effects of caffeic acid phenethyl ester (CAPE on palatal mucosal defects and tooth extraction sockets in an experimental model.Materials and methods: Forty-two male Sprague-Dawley rats with a mean age of 7 weeks and weighing 280–490 g were used in this study. The rats were randomly divided into two groups: group A (the control group, n=21 and group B (the experimental group, n=21. Under anesthesia with ketamine (8 mg/100 g, intraperitoneally, palatal mucosal defects were created and tooth extraction was performed in the rats in groups A and B. Group A received no treatment, whereas group B received CAPE. CAPE was injected daily (10 µmol/kg, intraperitoneally. The rats were killed on days 7, 14, and 30 after the procedures. Palatal mucosa healing and changes in bone tissue and fibrous tissue were evaluated histopathologically.Result: Pairwise comparisons showed no statistically significant difference between days 7 and 14 in either group (P>0.05. At day 30, bone healing was significantly better in group B (CAPE than in group A (control (P<0.05. Fibrinogen levels at day 30 were significantly higher in group A (control than in group B (CAPE (P<0.05. Pairwise comparisons showed no statistically significant difference in palatal mucosa healing levels between days 7 and 14 in both groups (P>0.05.Conclusion: In conclusion, the findings of this study suggest that CAPE can significantly improve tooth socket healing. Keywords: caffeic

  8. Repair of radius defect with bone-morphogenetic-protein loaded hydroxyapatite/collagen-poly(L-lactic acid) composite

    Institute of Scientific and Technical Information of China (English)

    胡蕴玉; 张超; 吕荣; 徐建强; 李丹

    2003-01-01

    Objective: To explore the method to repair bone defect with bone-morphogenetic-protein loaded hydroxyapatite/collagen-poly(L-lactic acid) composite. Methods: 18 adult beagle dogs were randomly divided into 3 groups. In Group A, bone-morphogenetic-protein (BMP) loaded hydroxyapatite/collagen-poly(L-lactic acid) (HAC-PLA) scaffold was implanted in a 2 cm diaphyseal defect in the radius. In Group B, unloaded pure HAC-PLA scaffold was implanted in the defects. No material was implanted in Group C (control group). The dogs were sacrificed 6 months postoperatively. Features of biocompatibility, biodegradability and osteoinduction were evaluated with histological, radiological examinations and bone mineral density (BMD) measurements.Results: In Group A, the radius defect healed after the treatment with BMP loaded HAC-PLA. BMD at the site of the defect was higher than that of the contralateral radius. Fibrous union developed in the animals of the control group. Conclusions: BMP not only promotes osteogenesis but also accelerates degradation of the biomaterials. Optimized design parameters of a three-dimensional porous biomaterial would give full scope to the role of BMP as an osteoinductive growth factor.

  9. IDH1 mutations alter citric acid cycle metabolism and increase dependence on oxidative mitochondrial metabolism.

    Science.gov (United States)

    Grassian, Alexandra R; Parker, Seth J; Davidson, Shawn M; Divakaruni, Ajit S; Green, Courtney R; Zhang, Xiamei; Slocum, Kelly L; Pu, Minying; Lin, Fallon; Vickers, Chad; Joud-Caldwell, Carol; Chung, Franklin; Yin, Hong; Handly, Erika D; Straub, Christopher; Growney, Joseph D; Vander Heiden, Matthew G; Murphy, Anne N; Pagliarini, Raymond; Metallo, Christian M

    2014-06-15

    Oncogenic mutations in isocitrate dehydrogenase 1 and 2 (IDH1/2) occur in several types of cancer, but the metabolic consequences of these genetic changes are not fully understood. In this study, we performed (13)C metabolic flux analysis on a panel of isogenic cell lines containing heterozygous IDH1/2 mutations. We observed that under hypoxic conditions, IDH1-mutant cells exhibited increased oxidative tricarboxylic acid metabolism along with decreased reductive glutamine metabolism, but not IDH2-mutant cells. However, selective inhibition of mutant IDH1 enzyme function could not reverse the defect in reductive carboxylation activity. Furthermore, this metabolic reprogramming increased the sensitivity of IDH1-mutant cells to hypoxia or electron transport chain inhibition in vitro. Lastly, IDH1-mutant cells also grew poorly as subcutaneous xenografts within a hypoxic in vivo microenvironment. Together, our results suggest therapeutic opportunities to exploit the metabolic vulnerabilities specific to IDH1 mutation. ©2014 American Association for Cancer Research.

  10. Physiological effects of γ-linolenic acid and sesamin on hepatic fatty acid synthesis and oxidation.

    Science.gov (United States)

    Ide, Takashi; Iwase, Haruka; Amano, Saaya; Sunahara, Saki; Tachihara, Ayuka; Yagi, Minako; Watanabe, Tsuyoshi

    2017-03-01

    Interrelated effects of γ-linolenic acid (GLA) and sesamin, a sesame lignan, on hepatic fatty acid synthesis and oxidation were examined. Rats were fed experimental diets supplemented with 0 or 2 g/kg sesamin (1:1 mixture of sesamin and episesamin) and containing 100 g/kg of palm oil (saturated fat), safflower oil rich in linoleic acid, or oil of evening primrose origin containing 43% GLA (GLA oil) for 18 days. In rats fed sesamin-free diets, GLA oil, compared with other oils, increased the activity and mRNA levels of various enzymes involved in fatty acid oxidation, except for some instances. Sesamin greatly increased these parameters, and the enhancing effects of sesamin on peroxisomal fatty acid oxidation rate and acyl-CoA oxidase, enoyl-CoA hydratase and acyl-CoA thioesterase activities were more exaggerated in rats fed GLA oil than in the animals fed other oils. The combination of sesamin and GLA oil also synergistically increased the mRNA levels of some peroxisomal fatty acid oxidation enzymes and of several enzymes involved in fatty acid metabolism located in other cell organelles. In the groups fed sesamin-free diets, GLA oil, compared with other oils, markedly reduced the activity and mRNA levels of various lipogenic enzymes. Sesamin reduced all these parameters, except for malic enzyme, in rats fed palm and safflower oils, but the effects were attenuated in the animals fed GLA oil. These changes by sesamin and fat type accompanied profound alterations in serum lipid levels. This may be ascribable to the changes in apolipoprotein-B-containing lipoproteins.

  11. The kinetics of oxidation of bilirubin and ascorbic acid in solution

    Science.gov (United States)

    Solomonov, A. V.; Rumyantsev, E. V.; Kochergin, B. A.; Antina, E. V.

    2012-07-01

    The results of a comparative study of the oxidation of bilirubin, ascorbic acid, and their mixture in aqueous solutions under the action of air oxygen and hydrogen peroxide are presented. The observed and true rate constants for the oxidation reactions were determined. It was shown that the oxidation of tetrapyrrole pigment occurred under these conditions bypassing the stage of biliverdin formation to monopyrrole products. Simultaneous oxidation of bilirubin and ascorbic acid was shown to be accompanied by the inhibition of ascorbic acid oxidation by bilirubin, whereas ascorbic acid itself activated the oxidation of bilirubin.

  12. Regulation and limitations to fatty acid oxidation during exercise

    DEFF Research Database (Denmark)

    Jeppesen, Jacob; Kiens, Bente

    2012-01-01

    Fatty acids (FA) as fuel for energy utilization during exercise originate from different sources: FA transported in the circulation either bound to albumin or as triacylglycerol (TG) carried by very low density lipoproteins (VLDL) and FA from lipolysis of muscle TG stores (IMTG). Despite a high...... rate of energy expenditure during high intensity exercise the total fatty acid oxidation is suppressed to below that observed during moderate intensity exercise. Although this has been known for many years, the mechanisms behind this phenomenon are still not fully elucidated. A failure of adipose...... tissue to deliver sufficient fatty acids to exercising muscle has been proposed, but evidence is emerging that factors within the muscle might be of more importance. The high rate of glycolysis during high intensity exercise might be the "driving force" via the increased production of acetyl CoA which...

  13. Kinetics and Mechanism of Oxidation of Glutamic Acid by N-Bromophthalimide in Aqueous Acidic Medium

    OpenAIRE

    2011-01-01

    The kinetics of oxidation of glutamic acid (Glu) with N-bromophthalimide (NBP) was studied in perchloric acid medium at 30 °C by potentiometric method. The reaction is first order each in NBP and glutamic acid and is negative fractional order in [H+]. Addition of KBr or the reaction product, phthalimide had no effect on the rate. Similarly variation of ionic strength of the medium did not affect the rate of the reaction. Also the rate increased with decrease in dielectric constant of the reac...

  14. Effects of a chitosan membrane coated with polylactic and polyglycolic acid on bone regeneration in a rat calvarial defect

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Ui-Won [Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-752l (Korea, Republic of); Song, Kun-Young [Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-752l (Korea, Republic of); Kim, Chang-Sung [Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-752l (Korea, Republic of); Lee, Yong-Keun [Department and Research Institute of Dental Biomaterials and Bioengineering, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-750 (Korea, Republic of); Cho, Kyoo-Sung [Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-752l (Korea, Republic of); Kim, Chong-Kwan [Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-752l (Korea, Republic of); Choi, Seong-Ho [Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-752l (Korea, Republic of)

    2007-09-15

    The purpose of this study was to evaluate the effects of a chitosan membrane coated with polylactic and polyglycolic acid (PLGA) on bone regeneration in a rat calvarial defect. Surgical implantation of chitosan membranes resulted in enhanced local bone formation at both 2 and 8 weeks. In conclusion, the chitosan membrane coated with PLGA had a significant potential to induce bone formation in the rat calvarial defect model. Within the selected PLGA dose range and observation intervals, there appeared to be no meaningful differences in bone formation.

  15. A microwave molecular solution based approach towards high-κ-tantalum(V)oxide nanoparticles: synthesis, dielectric properties and electron paramagnetic resonance spectroscopic studies of their defect chemistry.

    Science.gov (United States)

    Hoffmann, R C; Kaloumenos, M; Spiehl, D; Erdem, E; Repp, S; Weber, S; Schneider, J J

    2015-12-21

    Stable dispersions of tantalum oxide nanoparticles are accessible from solutions of tantalum(V) complexes with a mixed malonato and alkanolato ligand sphere in ethoxyethanol by microwave processing. The malonato ligand is cleaved during decomposition and acetic acid or acetic acid esters are formed as derived from in situ spectroscopic studies. The solubility of the tantalum precursor and the obtained particle size therefrom depend strongly on the type of alkanolato ligand moiety. Dispersions of the molecular complexes possess good film forming properties. Films with low surface roughness can be obtained by spincoating. These exhibited a dielectric constant of about 15 and disruptive strengths above 1.5 MV cm(-1). The electrical measurements indicate that the presence of moisture is detrimental with respect to the dielectric performance of the films. After removal of the solvent from the suspensions of the nanoparticles, the residue can be redispersed in aprotic solvents. The particles can be isolated therefrom by precipitation with pentane. XRD and HRTEM indicate that the material remains amorphous up to temperatures of 750 °C. XPS proved that only Ta2O5 is formed as lower oxidation states of Ta cannot be detected. A detailed EPR study allows us to gain insight into the surface defect chemistry. Multiple types of oxygen vacancies exist at the surface of the Ta2O5 particles which are influenced by additional calcination and annealing in a vacuum.

  16. A point defect model for the general and pitting corrosion on iron-oxide-electrolyte interface deduced from current oscillations

    CERN Document Server

    Pagitsas, M; Sazou, D

    2003-01-01

    Analysis of the passive-active oscillatory region of the Fe-0.75 M H sub 2 SO sub 4 system, perturbed by adding small amounts of halide species, allow the distinction between pitting and general corrosion. Complex periodic and aperiodic current oscillations characterize pitting corrosion whereas monoperiodic oscillations of a relaxation type indicate general corrosion. A point defect model (PDM) is considered for the microscopic description of the growth and breakdown of the iron oxide film. The physicochemical processes leading to different types of corrosion can be clarified in terms of the PDM. Occupation of an anion vacancy by a halide ion results in the localized attack of the passive oxide and pitting corrosion. On the other hand, the formation of surface soluble iron complexes is related to the uniform dissolution of the passive oxide and general corrosion.

  17. Methylmalonic Acid in Amniotic Fluid and Maternal Urine as a Marker for Neural Tube Defects

    Institute of Scientific and Technical Information of China (English)

    罗小平; 张炼; 魏虹; 刘皖君; 王慕逖; 宁琴

    2004-01-01

    To evaluate the implication of methymalonic acid (MMA) in the early diagnosis of neural tube defects (NTD), a quantitative assay for MMA was established by using gas chromatographymass spectrometry with stable isotope of MMA as an internal standard. Amniotic fluid and maternal urine MMA concentration, maternal serum folate, red blood cell folate and vitamin B12 levels were measured in the middle term of NTD-affected and normal pregnancies. Amniotic fluid and maternal urine MMA concentrations in the middle term of NTD affected pregnancies (1.4 ± 0.9 μmol/L, and 22.1 ± 12.6 nmol/μmol creatinine) were significantly higher than that of normal pregnancies (1.0±0.4μ mol/L, and 2.5± 1.1 nmol/μmol creatinine). There was no significant difference between normal and NTD pregnancies for serum folate, red blood cell folate and vitamin B12 levels.The results suggested that MMAs in amniotic fluid and maternal urine are sensitive markers for early diagnosis of NTD. Vitamin B12 is an active cofactor involved in the remethylation of homocycteine and its deficiency is an independent risk factor for NTD. MMA is a specific and sensitive marker for intracellular vitamin B12 deficiency. This study suggests that it is necessary to monitor the vitamin B12 deficiency and advocates vitamin B12 supplementation with folate prevention program.

  18. Acetic acid enhances endurance capacity of exercise-trained mice by increasing skeletal muscle oxidative properties.

    Science.gov (United States)

    Pan, Jeong Hoon; Kim, Jun Ho; Kim, Hyung Min; Lee, Eui Seop; Shin, Dong-Hoon; Kim, Seongpil; Shin, Minkyeong; Kim, Sang Ho; Lee, Jin Hyup; Kim, Young Jun

    2015-01-01

    Acetic acid has been shown to promote glycogen replenishment in skeletal muscle during exercise training. In this study, we investigated the effects of acetic acid on endurance capacity and muscle oxidative metabolism in the exercise training using in vivo mice model. In exercised mice, acetic acid induced a significant increase in endurance capacity accompanying a reduction in visceral adipose depots. Serum levels of non-esterified fatty acid and urea nitrogen were significantly lower in acetic acid-fed mice in the exercised mice. Importantly, in the mice, acetic acid significantly increased the muscle expression of key enzymes involved in fatty acid oxidation and glycolytic-to-oxidative fiber-type transformation. Taken together, these findings suggest that acetic acid improves endurance exercise capacity by promoting muscle oxidative properties, in part through the AMPK-mediated fatty acid oxidation and provide an important basis for the application of acetic acid as a major component of novel ergogenic aids.

  19. Advanced oxidation processes of decomposing dichloroacetic acid and trichloroacetic acid in water

    Institute of Scientific and Technical Information of China (English)

    WANG Kun-ping; GUO Jin-song; YANG Min; JUNJI Hirotsuji; DENG Rong-sen; LIU Wei

    2008-01-01

    We studied the decomposition of two haloacetic acids (HAAs), dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA), in water by single oxidants ozone (O3) and ultraviolet radiation (UV) and the advanced oxidation processes (AOPs) constituted by the combinations of O3/UV, H2O2/UV, O3 /H2O2, and O3/H2O2/UV. The concentrations of HAAs were analyzed at specified time intervals to track their decomposition. Except for O3 and UV, the four combined oxidation processes remarkably enhance the decomposition of DCAA and TCAA owing to the generated very reactive hydroxyl radicals. The fastest decomposition process is O3/H2O2/UV, closely followed by O3/UV. DCAA is much easier to decompose than TCAA. The kinetics of HAA decomposition by O3/UV can be described well by a pseudo first-order reaction model under a constant initial dissolved O3 concentration and fixed UV radiation. Humic acids and HCO3- in the reaction system both decrease the decomposition rate constants for DCAA and TCAA. The amount of H2O2 accumulates in the presence of humic acids in the O3/UV process.

  20. Importance of acid-base equilibrium in electrocatalytic oxidation of formic acid on platinum.

    Science.gov (United States)

    Joo, Jiyong; Uchida, Taro; Cuesta, Angel; Koper, Marc T M; Osawa, Masatoshi

    2013-07-10

    Electro-oxidation of formic acid on Pt in acid is one of the most fundamental model reactions in electrocatalysis. However, its reaction mechanism is still a matter of strong debate. Two different mechanisms, bridge-bonded adsorbed formate mechanism and direct HCOOH oxidation mechanism, have been proposed by assuming a priori that formic acid is the major reactant. Through systematic examination of the reaction over a wide pH range (0-12) by cyclic voltammetry and surface-enhanced infrared spectroscopy, we show that the formate ion is the major reactant over the whole pH range examined, even in strong acid. The performance of the reaction is maximal at a pH close to the pKa of formic acid. The experimental results are reasonably explained by a new mechanism in which formate ion is directly oxidized via a weakly adsorbed formate precursor. The reaction serves as a generic example illustrating the importance of pH variation in catalytic proton-coupled electron-transfer reactions.

  1. Reduction Rates for Higher Americium Oxidation States in Nitric Acid

    Energy Technology Data Exchange (ETDEWEB)

    Grimes, Travis Shane [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mincher, Bruce Jay [Idaho National Lab. (INL), Idaho Falls, ID (United States); Schmitt, Nicholas C [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-09-30

    The stability of hexavalent americium was measured using multiple americium concentrations and nitric acid concentrations after contact with the strong oxidant sodium bismuthate. Contrary to our hypotheses Am(VI) was not reduced faster at higher americium concentrations, and the reduction was only zero-order at short time scales. Attempts to model the reduction kinetics using zero order kinetic models showed Am(VI) reduction in nitric acid is more complex than the autoreduction processes reported by others in perchloric acid. The classical zero-order reduction of Am(VI) was found here only for short times on the order of a few hours. We did show that the rate of Am(V) production was less than the rate of Am(VI) reduction, indicating that some Am(VI) undergoes two electron-reduction to Am(IV). We also monitored the Am(VI) reduction in contact with the organic diluent dodecane. A direct comparison of these results with those in the absence of the organic diluent showed the reduction rates for Am(VI) were not statistically different for both systems. Additional americium oxidations conducted in the presence of Ce(IV)/Ce(III) ions showed that Am(VI) is reduced without the typical growth of Am(V) observed in the systems sans Ce ion. This was an interesting result which suggests a potential new reduction/oxidation pathway for Am in the presence of Ce; however, these results were very preliminary, and will require additional experiments to understand the mechanism by which this occurs. Overall, these studies have shown that hexavalent americium is fundamentally stable enough in nitric acid to run a separations process. However, the complicated nature of the reduction pathways based on the system components is far from being rigorously understood.

  2. 'Low-acid' sulfide oxidation using nitrate-enriched groundwater

    Science.gov (United States)

    Donn, Michael; Boxall, Naomi; Reid, Nathan; Meakin, Rebecca; Gray, David; Kaksonen, Anna; Robson, Thomas; Shiers, Denis

    2016-04-01

    Acid drainage (AMD/ARD) is undoubtedly one of the largest environmental, legislative and economic challenges facing the mining industry. In Australia alone, at least 60m is spent on AMD related issues annually, and the global cost is estimated to be in the order of tens of billions US. Furthermore, the challenge of safely and economically storing or treating sulfidic wastes will likely intensify because of the trend towards larger mines that process increasingly higher volumes of lower grade ores and the associated sulfidic wastes and lower profit margins. While the challenge of managing potentially acid forming (PAF) wastes will likely intensify, the industrial approaches to preventing acid production or ameliorating the effects has stagnated for decades. Conventionally, PAF waste is segregated and encapsulated in non-PAF tips to limit access to atmospheric oxygen. Two key limitations of the 'cap and cover' approach are: 1) the hazard (PAF) is not actually removed; only the pollutant linkage is severed; and, 2) these engineered structures are susceptible to physical failure in short-to-medium term, potentially re-establishing that pollutant linkage. In an effort to address these concerns, CSIRO is investigating a passive, 'low-acid' oxidation mechanism for sulfide treatment, which can potentially produce one quarter as much acidity compared with pyrite oxidation under atmospheric oxygen. This 'low-acid' mechanism relies on nitrate, rather than oxygen, as the primary electron accepter and the activity of specifically cultured chemolithoautotrophic bacteria and archaea communities. This research was prompted by the observation that, in deeply weathered terrains of Australia, shallow (oxic to sub-oxic) groundwater contacting weathering sulfides are commonly inconsistent with the geochemical conditions produced by ARD. One key characteristic of these aquifers is the natural abundance of nitrate on a regional scale, which becomes depleted around the sulfide bodies, and

  3. Knowledge and practice of urban Iranian pregnant women towards folic acid intake for neural tube defect prevention.

    Science.gov (United States)

    Nosrat, Sepideh Bakhshande; Sedehi, Maliheh; Golalipour, Mohammad Jafar

    2012-08-01

    To assess the knowledge and practice of urban Iranian pregnant women regarding periconceptional folic acid intake for neural tube defect (NTD) prevention. The population-based study was done on 676 primiparous women in an urban area in Golestan province in northern Iran from June to November, 2008. A questionnaire was completed by the subjects regarding their knowledge of folic acid. Questionnaires were administered to women who were seeking routine antenatal care at health centres, private gynaecological clinic and the Dezyani Gynaecologic and Obstetric Hospital. Questions covered knowledge and use of folic acid supplements and demographic and socioeconomic characteristics. Out of the 676 women surveyed, 96.2% reported that they heard of folate. Of these, only 27.6% knew that folate was something important in the prevention of neural tube defects. Overall, 20.12% of the total women took folic acid during periconceptional period. The most common information sources on folate were healthcare service (54.5%). Besides, 37.6% of the subjects who heard about folate were aware that green leafy vegetables were fortified with folic acid. In univariate analysis, knowledge and intake of folic acid was not associated with education and the age of women. A healthcare plan for intervention to increase the knowledge and intake of folic acid by pregnant women during the protective period is required.

  4. Influence of Atomic Hydrogen, Band Bending, and Defects in the Top Few Nanometers of Hydrothermally Prepared Zinc Oxide Nanorods

    Science.gov (United States)

    Al-Saadi, Mubarak J.; Al-Harthi, Salim H.; Kyaw, Htet H.; Myint, Myo T. Z.; Bora, Tanujjal; Laxman, Karthik; Al-Hinai, Ashraf; Dutta, Joydeep

    2017-01-01

    We report on the surface, sub-surface (top few nanometers) and bulk properties of hydrothermally grown zinc oxide (ZnO) nanorods (NRs) prior to and after hydrogen treatment. Upon treating with atomic hydrogen (H*), upward and downward band bending is observed depending on the availability of molecular H2O within the structure of the NRs. In the absence of H2O, the H* treatment demonstrated a cleaning effect of the nanorods, leading to a 0.51 eV upward band bending. In addition, enhancement in the intensity of room temperature photoluminescence (PL) signals due to the creation of new surface defects could be observed. The defects enhanced the visible light activity of the ZnO NRs which were subsequently used to photocatalytically degrade aqueous phenol under simulated sunlight. On the contrary, in the presence of H2O, H* treatment created an electronic accumulation layer inducing downward band bending of 0.45 eV ( 1/7th of the bulk ZnO band gap) along with the weakening of the defect signals as observed from room temperature photoluminescence spectra. The results suggest a plausible way of tailoring the band bending and defects of the ZnO NRs through control of H2O/H* species.

  5. Lipotoxic Palmitate Impairs the Rate of β-Oxidation and Citric Acid Cycle Flux in Rat Neonatal Cardiomyocytes.

    Science.gov (United States)

    Haffar, Taha; Akoumi, Ali; Bousette, Nicolas

    2016-01-01

    Diabetic hearts exhibit intracellular lipid accumulation. This suggests that the degree of fatty acid oxidation (FAO) in these hearts is insufficient to handle the elevated lipid uptake. We previously showed that palmitate impaired the rate of FAO in primary rat neonatal cardiomyocytes. Here we were interested in characterizing the site of FAO impairment induced by palmitate since it may shed light on the metabolic dysfunction that leads to lipid accumulation in diabetic hearts. We measured fatty acid oxidation, acetyl-CoA oxidation, and carnitine palmitoyl transferase (Cpt1b) activity. We measured both forward and reverse aconitase activity, as well as NAD+ dependent isocitrate dehydrogenase activity. We also measured reactive oxygen species using the 2', 7'-Dichlorofluorescin Diacetate (DCFDA) assay. Finally we used thin layer chromatography to assess diacylglycerol (DAG) levels. We found that palmitate significantly impaired mitochondrial β-oxidation as well as citric acid cycle flux, but not Cpt1b activity. Palmitate negatively affected net aconitase activity and isocitrate dehydrogenase activity. The impaired enzyme activities were not due to oxidative stress but may be due to DAG mediated PKC activation. This work demonstrates that palmitate, a highly abundant fatty acid in human diets, causes impaired β-oxidation and citric acid cycle flux in primary neonatal cardiomyocytes. This metabolic defect occurs prior to cell death suggesting that it is a cause, rather than a consequence of palmitate mediated lipotoxicity. This impaired mitochondrial metabolism can have important implications for metabolic diseases such as diabetes and obesity. © 2016 The Author(s) Published by S. Karger AG, Basel.

  6. Lipotoxic Palmitate Impairs the Rate of β-Oxidation and Citric Acid Cycle Flux in Rat Neonatal Cardiomyocytes

    Directory of Open Access Journals (Sweden)

    Taha Haffar

    2016-12-01

    Full Text Available Background/Aims: Diabetic hearts exhibit intracellular lipid accumulation. This suggests that the degree of fatty acid oxidation (FAO in these hearts is insufficient to handle the elevated lipid uptake. We previously showed that palmitate impaired the rate of FAO in primary rat neonatal cardiomyocytes. Here we were interested in characterizing the site of FAO impairment induced by palmitate since it may shed light on the metabolic dysfunction that leads to lipid accumulation in diabetic hearts. Methods: We measured fatty acid oxidation, acetyl-CoA oxidation, and carnitine palmitoyl transferase (Cpt1b activity. We measured both forward and reverse aconitase activity, as well as NAD+ dependent isocitrate dehydrogenase activity. We also measured reactive oxygen species using the 2', 7'-Dichlorofluorescin Diacetate (DCFDA assay. Finally we used thin layer chromatography to assess diacylglycerol (DAG levels. Results: We found that palmitate significantly impaired mitochondrial β-oxidation as well as citric acid cycle flux, but not Cpt1b activity. Palmitate negatively affected net aconitase activity and isocitrate dehydrogenase activity. The impaired enzyme activities were not due to oxidative stress but may be due to DAG mediated PKC activation. Conclusion: This work demonstrates that palmitate, a highly abundant fatty acid in human diets, causes impaired β-oxidation and citric acid cycle flux in primary neonatal cardiomyocytes. This metabolic defect occurs prior to cell death suggesting that it is a cause, rather than a consequence of palmitate mediated lipotoxicity. This impaired mitochondrial metabolism can have important implications for metabolic diseases such as diabetes and obesity.

  7. Mitochondrial free fatty acid β-oxidation supports oxidative phosphorylation and proliferation in cancer cells.

    Science.gov (United States)

    Rodríguez-Enríquez, Sara; Hernández-Esquivel, Luz; Marín-Hernández, Alvaro; El Hafidi, Mohammed; Gallardo-Pérez, Juan Carlos; Hernández-Reséndiz, Ileana; Rodríguez-Zavala, José S; Pacheco-Velázquez, Silvia C; Moreno-Sánchez, Rafael

    2015-08-01

    Oxidative phosphorylation (OxPhos) is functional and sustains tumor proliferation in several cancer cell types. To establish whether mitochondrial β-oxidation of free fatty acids (FFAs) contributes to cancer OxPhos functioning, its protein contents and enzyme activities, as well as respiratory rates and electrical membrane potential (ΔΨm) driven by FFA oxidation were assessed in rat AS-30D hepatoma and liver (RLM) mitochondria. Higher protein contents (1.4-3 times) of β-oxidation (CPT1, SCAD) as well as proteins and enzyme activities (1.7-13-times) of Krebs cycle (KC: ICD, 2OGDH, PDH, ME, GA), and respiratory chain (RC: COX) were determined in hepatoma mitochondria vs. RLM. Although increased cholesterol content (9-times vs. RLM) was determined in the hepatoma mitochondrial membranes, FFAs and other NAD-linked substrates were oxidized faster (1.6-6.6 times) by hepatoma mitochondria than RLM, maintaining similar ΔΨm values. The contents of β-oxidation, KC and RC enzymes were also assessed in cells. The mitochondrial enzyme levels in human cervix cancer HeLa and AS-30D cells were higher than those observed in rat hepatocytes whereas in human breast cancer biopsies, CPT1 and SCAD contents were lower than in human breast normal tissue. The presence of CPT1 and SCAD in AS-30D mitochondria and HeLa cells correlated with an active FFA utilization in HeLa cells. Furthermore, the β-oxidation inhibitor perhexiline blocked FFA utilization, OxPhos and proliferation in HeLa and other cancer cells. In conclusion, functional mitochondria supported by FFA β-oxidation are essential for the accelerated cancer cell proliferation and hence anti-β-oxidation therapeutics appears as an alternative promising approach to deter malignant tumor growth.

  8. Kinetics and mechanism of the oxidation of some -hydroxy acids by hexamethylenetetramine-bromine

    Indian Academy of Sciences (India)

    Dimple Garg; Seema Kothari

    2004-11-01

    The oxidation of lactic acid, mandelic acid and ten monosubstituted mandelic acids by hexamethylenetetramine-bromine (HABR) in glacial acetic acid, leads to the formation of the corresponding oxoacid. The reaction is first order with respect to each of the hydroxy acids and HABR. It is proposed that HABR itself is the reactive oxidizing species. The oxidation of -deuteriomandelic acid exhibits the presence of a substantial kinetic isotope effect (/ = 5.91 at 298 K). The rates of oxidation of the substituted mandelic acids show excellent correlation with Brown’s + values. The reaction constants are negative. The oxidation exhibits an extensive cross conjugation between the electron-donating substituent and the reaction centre in the transition state. A mechanism involving transfer of a hydride ion from the acid to the oxidant is postulated.

  9. Relationship between Photocatalytic Activity and Ti{sup 3+} Defects in Acid-Leached Titanium Dioxide / Hydroxyapatite Composite

    Energy Technology Data Exchange (ETDEWEB)

    Ono, Y; Rachi, T; Okuda, T; Yokouchi, M; Kamimoto, Y [Mechanical and Material Engineering Division, Kanagawa Industrial Technology Center, 705-1 Shimo-imaizumi, Ebina, Kanagawa 243-0435 (Japan); Nakajima, A [Department of Metallurgy and Ceramics Science, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552 (Japan); Okada, K, E-mail: ono-y@kanagawa-iri.go.jp [Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuda, Midori-ku, Yokohama 226-8503 (Japan)

    2011-10-29

    Effect of Ti{sup 3+} defect density on the photocatalytic activity was investigated using electron spin resonance (ESR) spectroscopy under UV irradiation at 103K. The Ti{sup 3+} signal intensity decreased with increasing heating temperature for the TiO{sub 2} powders prepared by hydroxyapatite (HAp) precipitation, heating and acid leaching process. The Ti{sup 3+} defect density of the TiO{sub 2} powder heat-treated at 700 deg. C was found to be about half that of the starting material, P25, without anatase-to-rutile phase transformation based on the results of X-ray diffraction. The photocatalytic activity of the TiO{sub 2} powder determined from the change of methylene blue concentration under UV irradiation became higher with decreasing of the Ti{sup 3+} defects without a significant change in the anatase ratio and specific surface area during the heat treatment.

  10. Quinolinic acid induces oxidative stress in rat brain synaptosomes.

    Science.gov (United States)

    Santamaría, A; Galván-Arzate, S; Lisý, V; Ali, S F; Duhart, H M; Osorio-Rico, L; Ríos, C; St'astný, F

    2001-03-26

    The oxidative action of quinolinic acid (QUIN), and the protective effects of glutathione (GSH), and 2-amino-5-phosphonovaleric acid (APV), were tested in rat brain synaptosomes, Reactive oxygen species (ROS) formation was quantified after the exposure of synaptosomes to increasing concentrations of QUIN (25-500 microM). The potency of QUIN to induce lipid peroxidation (LP) was tested as a regional index of thiobarbituric acid-reactive substances (TBARS) production, and the antioxidant actions of both GSH (50 microM) and APV (250 microM) on QUIN-induced LP were evaluated in synaptosomes prepared from different brain regions. QUIN induced concentration-dependent increases in ROS formation and TBARS in all regions analyzed, but increased production of fluorescent peroxidized lipids only in the striatum and the hippocampus, whereas both GSH and APV decreased this index. These results suggest that the excitotoxic action of QUIN involves regional selectivity in the oxidative status of brain synaptosomes, and may be prevented by substances exhibiting antagonism at the NMDA receptor.

  11. Fatty acids and oxidative stress in psychiatric disorders

    Directory of Open Access Journals (Sweden)

    Tonello Lucio

    2008-04-01

    Full Text Available Abstract Background The aim of this study was to determine whether there is published evidence for increased oxidative stress in neuropsychiatric disorders. Methods A PubMed search was carried out using the MeSH search term 'oxidative stress' in conjunction with each of the DSM-IV-TR diagnostic categories of the American Psychiatric Association in order to identify potential studies. Results There was published evidence of increased oxidative stress in the following DSM-IV-TR diagnostic categories: mental retardation; autistic disorder; Rett's disorder; attention-deficit hyperactivity disorder; delirium; dementia; amnestic disorders; alcohol-related disorders; amphetamine (or amphetamine-like-related disorders; hallucinogen-related disorders; nicotine-related disorders; opioid-related disorders; schizophrenia and other psychotic disorders; mood disorders; anxiety disorders; sexual dysfunctions; eating disorders; and sleep disorders. Conclusion Most psychiatric disorders are associated with increased oxidative stress. Patients suffering from that subgroup of these psychiatric disorders in which there is increased lipid peroxidation might therefore benefit from fatty acid supplementation (preferably with the inclusion of an antioxidant-rich diet while patients suffering from all these psychiatric disorders might benefit from a change to a whole-food plant-based diet devoid of refined carbohydrate products.

  12. Phosphonic Acids for Interfacial Engineering of Transparent Conductive Oxides

    KAUST Repository

    Paniagua, Sergio A.

    2016-05-26

    Transparent conducting oxides (TCOs), such as indium tin oxide and zinc oxide, play an important role as electrode materials in organic-semiconductor devices. The properties of the inorganic-organic interface - the offset between the TCO Fermi level and the relevant transport level, the extent to which the organic semiconductor can wet the oxide surface, and the influence of the surface on semiconductor morphology - significantly affect device performance. This review surveys the literature on TCO modification with phosphonic acids (PAs), which has increasingly been used to engineer these interfacial properties. The first part outlines the relevance of TCO surface modification to organic electronics, surveys methods for the synthesis of PAs, discusses the modes by which they can bind to TCO surfaces, and compares PAs to alternative organic surface modifiers. The next section discusses methods of PA monolayer deposition, the kinetics of monolayer formation, and structural evidence regarding molecular orientation on TCOs. The next sections discuss TCO work-function modification using PAs, tuning of TCO surface energy using PAs, and initiation of polymerizations from TCO-tethered PAs. Finally, studies that examine the use of PA-modified TCOs in organic light-emitting diodes and organic photovoltaics are compared. © 2016 American Chemical Society.

  13. Oxidation of cumene in an aprotic medium in the presence of ascorbic acid

    Science.gov (United States)

    Smirnova, O. V.; Efimova, I. V.; Opeida, I. A.

    2015-06-01

    The process of the initiated oxidation of cumene (IPB) with oxygen under homophase conditions in the presence of ascorbic acid (AA) used over a wide range of concentrations is studied. It is shown that in this system, ascorbic acid is consumed in two ways: the auto-oxidation and the inhibition of the oxidation of cumene. The amount of ascorbic acid that participates in inhibiting the oxidation of cumene falls from 28.5 to 16.6% with a rise in the concentration of ascorbic acid in the range of 0.003-0.3 mol/L. The contribution from the rate of the oxidation of ascorbic acid to the total rate of the oxidation of the IPB-AA-DMSO-AIBN system grows from 67.2 to 92.5% with a rise in the concentration of ascorbic acid in the range of 0.01-0.3 mol/L. It is established that the most effective inhibition of the oxidation of cumene with ascorbic acid in aprotic media occurs at concentrations of ascorbic acid of up to 0.01 mol/L. A scheme for the initiated radical-chain oxidation of cumene with ascorbic acid in the aprotic medium that considers the inhibition of the oxidation of cumene with ascorbic acid and the auto-oxidation of ascorbic acid is proposed.

  14. Single-crystalline Pd square nanoplates enclosed by {100} facets on reduced graphene oxide for formic acid electro-oxidation.

    Science.gov (United States)

    Jiang, Yi; Yan, Yucong; Chen, Wenlong; Khan, Yousaf; Wu, Jianbo; Zhang, Hui; Yang, Deren

    2016-12-06

    Single-crystalline Pd square nanoplates enclosed by {100} facets were generated on reduced graphene oxide and exhibited the substantially enhanced properties for the formic acid oxidation reaction. The combination of carbonyl groups formed on the surface of annealed graphene oxide and Br(-) ions played important roles in this synthesis.

  15. [Attitudes of pregnant Japanese women and folic acid intake for the prevention of neural tube defects: a nationwide Internet survey].

    Science.gov (United States)

    Sato, Yoko; Nakanishi, Tomoko; Chiba, Tsuyoshi; Umegaki, Keizo

    2014-01-01

    Folic acid intake is recommended for pregnant women because it significantly reduces the risk of neural tube defects (NTD) in the fetus. However, the risk of NTD remains medium in Japan. In this study, the attitudes of pregnant Japanese women and factors related to folic acid intake for the prevention of NTD were evaluated using a nationwide survey. An Internet-based questionnaire was conducted on 2,367 pregnant Japanese women who were registrants of a Japanese social research company in January 2012; 1,236 of these women responded. In the questionnaires, the knowledge regarding the folate intake (i.e., name of folic acid, the risk of NTD, recommended doses, and timing), actual intake of folic acid, demographic factors (i.e., age, geographical area, gestational age, and birth order), and intake of dietary supplements were surveyed. Eighty-five percent of respondents consumed folate, which was mostly obtained through dietary folic acid supplements during the first month of pregnancy or after. Factors associated with loss of folic acid intake until 3 months of pregnancy included lack of knowledge, failure to consume dietary supplements, younger age, and multigravida. Many pregnant women in Japan consumed folic acid. However, most of them started supplementation after pregnancy recognition, which is too late to reduce the risk of NTD. Alternative strategies to increase the efficacy of folic acid intake, such as recommending folic acid-enriched foods, promoting folic acid fortification efforts, and providing access to practical information, are necessary.

  16. Electro-oxidation of methanol and formic acid on platinum nanoparticles with different oxidation levels

    Energy Technology Data Exchange (ETDEWEB)

    Hsieh, Chien-Te, E-mail: cthsieh@saturn.yzu.edu.tw [Department of Chemical Engineering and Materials Science, Yuan Ze University, Taoyuan 320, Taiwan (China); Hsiao, Han-Tsung; Tzou, Dong-Ying; Yu, Po-Yuan [Department of Chemical Engineering and Materials Science, Yuan Ze University, Taoyuan 320, Taiwan (China); Chen, Po-Yen; Jang, Bi-Sheng [Materials and Electro-Optics Research Division, National Chung-Shan Institute of Science and Technology, Taoyuan 325, Taiwan (China)

    2015-01-15

    Herein reported is an atomic layer deposition (ALD) process of platinum (Pt) from (methylcyclopentadienyl) trimethylplatinum (MeCpPtMe{sub 3}) and oxygen (O{sub 2}) for synthesizing the Pt electrocatalysts toward methanol and formic acid oxidation. The as-synthesized Pt catalysts are thermally reduced in 5 vol% H{sub 2} within temperature window of 150–450 °C. The reduction treatment induces a decrease in amount of Pt oxide (Pt–O) species, e.g., PtO and PtO{sub 2}. The presence of Pt–O species not only enhances catalytic activity but also improves anti-poisoning ability toward the oxidation of methanol and formic acid. The improved activity originates from the fact that the Pt–O species, formed by the ALD route, creates a large number of active sites (e.g., Pt–O{sub ads} and Pt–(OH){sub ads}) to strip the CO-adsorbed sites, leading to a high-level of CO tolerance. This work also proposes a stepwise reaction steps to shed some lights on how the Pt–O species promote the catalytic activity. - Highlights: • This study adopts atomic layer deposition (ALD) to grow metallic Pt nanoparticles. • The Pt catalysts show catalytic activity toward methanol and formic acid oxidation. • The reduction treatment induces a decrease in amount of Pt oxide (Pt–O) species. • The Pt–O species creates a number of active sites to strip the CO-adsorbed sites. • A stepwise reaction step concerning the promoted catalytic activity is proposed.

  17. Iron photoreduction and oxidation in an acidic mountain stream.

    Science.gov (United States)

    McKnight, D M; Kimball, B A; Bencala, K E

    1988-04-29

    In a small mountain stream in Colorado that receives acidic mine drainage, photoreduction of ferric iron results in a well-defined increase in dissolved ferrous iron during the day. To quantify this process, an instream injection of a conservative tracer was used to measure discharge at the time that each sample was collected. Daytime production of ferrous iron by photoreduction was almost four times as great as nighttime oxidation of ferrous iron. The photoreduction process probably involves dissolved or colloidal ferric iron species and limited interaction with organic species because concentrations of organic carbon are low in this stream.

  18. Electronic properties and native point defects of high efficient NO oxidation catalysts SmMn2O5

    Science.gov (United States)

    Li, Hao-Bo; Yang, Zhi; Liu, Jieyu; Yao, Xiaolong; Xiong, Ka; Liu, Hui; Wang, Wei-Hua; Lu, Feng; Wang, Weichao

    2016-11-01

    Mn-based oxide SmMn2O5 exhibits great catalytic performance in NO oxidation [Wang et al., Science 337, 832 (2012)]. Nevertheless, the fundamental understanding of SmMn2O5 properties is so far not fully accessible. Here, the SmMn2O5 nanoparticles are synthesized through hydrothermal methods, and the pure phase of triclinic SmMn2O5 is characterized by high-resolution tunneling electron microscope and X-ray diffraction. Furthermore, the X-ray photoelectron spectroscopy, absorption, photoluminescence spectra (PL), and density functional theory based first-principles calculations are employed to explore the fundamental electronic structures of pristine and defective SmMn2O5. Combined with band structure calculations, light absorption, and PL spectra, we first show that SmMn2O5 presents an insulating behavior with an indirect band gap of ˜1.0 eV. Between the two types of crystal fields, i.e., octahedral and tetrahedral, the later one contributes to the dz2 of the valence band edge, resulting in superior catalytic performance of NO oxidation. Furthermore, the native point defects in SmMn2O5 are first reported. Among the various native point defects, we demonstrate that oxygen vacancy (VO) shows the lowest formation energy in oxygen poor conditions, while the oxygen interstitial (Oi) and Mn vacancies are energetically favorable in oxygen rich situations. In other words, SmMn2O5 could be potentially utilized as an oxygen storage material.

  19. Trends in neural tube defect prevalence, folic acid fortification, and vitamin supplement use.

    Science.gov (United States)

    Olney, Richard S; Mulinare, Joseph

    2002-08-01

    In this review, the authors analyze international trends in rates of neural tube defects (NTDs) during the past three decades. Population-based data sources include the Metropolitan Atlanta Congenital Defects Program and other US birth defects surveillance programs in the National Birth Defects Prevention Network, the International Clearinghouse for Birth Defects Monitoring Systems, and US and Canadian vital records. To analyze trends in vitamin consumption, we review data from the US National Health and Nutrition Examination Surveys and international surveys of multivitamin use. We discuss the role of factors associated with historic and continuing declines in NTD rates in most countries. These factors include the introduction and increased utilization of prenatal diagnosis, recommendations for multivitamin use in women of childbearing age, and population-wide increases in blood folate levels that have occurred since food fortification was mandated. We also discuss research needs for further NTD prevention. This is a US government work. There are no restrictions on its use.

  20. Effects of phenformin and alpha-bromopalmitate on fatty acid and glucose oxidation in muscle.

    Science.gov (United States)

    Tutwiler, G F

    1978-03-01

    Hemidiaphragms removed from fasted rats which were treated with the fatty acid oxidation inhibitor, alpha-bromopalmitate (125-250 mg/kg, i.p.) oxidized less glucose to CO2 than vehicle-treated rats. Hypoglycemia was noted and was preceded by reduction of muscle palmitate oxidation and by increased plasma free fatty acids (FFA). However, phenformin (100 mg/kg, i.p.) lowered plasma FFA and diaphragm oxidation of both palmitic acid and glucose, without altering glucose levels. These results fail to support the hypothesis that phenformin lowers blood glucose secondary to inhibiton of fatty acid oxidation.

  1. Oxidized Fatty Acids as Inter-Kingdom Signaling Molecules

    Directory of Open Access Journals (Sweden)

    Carolina H. Pohl

    2014-01-01

    Full Text Available Oxylipins or oxidized fatty acids are a group of molecules found to play a role in signaling in many different cell types. These fatty acid derivatives have ancient evolutionary origins as signaling molecules and are ideal candidates for inter-kingdom communication. This review discusses examples of the ability of organisms from different kingdoms to “listen” and respond to oxylipin signals during interactions. The interactions that will be looked at are signaling between animals and plants; between animals and fungi; between animals and bacteria and between plants and fungi. This will aid in understanding these interactions, which often have implications in ecology, agriculture as well as human and animal health.

  2. The Study of Nitric Oxide Effects in Control of Mouse Preimplantation Embryonic Defects in High Glucosis Media

    Directory of Open Access Journals (Sweden)

    I. Amiri

    2003-10-01

    Full Text Available Pregnancy in diabetic females causes delay in early stages of embryonic growth and development and higher incidence of congenital malformations and spontaneous miscarriage compared with those of non- diabetic conditions. High glucosis tratogenicity seems to be related to reduction of Nitric Oxide production (NO in hyperglycemic condition. The goal of present work was study of nitric oxid role in control of mouse preimplantation embryonic defects in high glucosis media. In order to test above hypothesis, 2-cell stage embryos of normal mice were cultured with high concentration of glucose (30mM and different concentrations of L-arginine (5,10,20 mM or L-NAME (An antagonist of L- arginine. After 96h culture, the morphology of embryos was assessed by an inverted microscope then blastocysts were stained by TUNEL. After TUNEL the total cell number and apoptotic cells were counted by use a Fluorescence microscope. Finally the amount of nitrite in the media was assayed by Greiss method. The results indicated that high glucose decreases the blastocyst formation and Nitric Oxide production and increases their apoptotic index, but 10-20mM L-arginine significantly increases the developmental potential and nitric oxide production and significantly decreases apoptosis. On the contrary L-NAME significantly inhibits the development of pre-implantation embryos . It seems that during pregnancy supplementation of high glucose media with L-arginine increases Nitric Oxide production and prevents high glucosis embryotoxicity.

  3. Electronic Structure of the Perylene / Zinc Oxide Interface: A Computational Study of Photoinduced Electron Transfer and Impact of Surface Defects

    KAUST Repository

    Li, Jingrui

    2015-07-29

    The electronic properties of dye-sensitized semiconductor surfaces consisting of pery- lene chromophores chemisorbed on zinc oxide via different spacer-anchor groups, have been studied at the density-functional-theory level. The energy distributions of the donor states and the rates of photoinduced electron transfer from dye to surface are predicted. We evaluate in particular the impact of saturated versus unsaturated aliphatic spacer groups inserted between the perylene chromophore and the semiconductor as well as the influence of surface defects on the electron-injection rates.

  4. Hepatic fatty acid oxidation : activity, localization and function of some enzymes involved

    NARCIS (Netherlands)

    A. van Tol (Arie)

    1971-01-01

    textabstractFatty acid oxidation is an important pathway for energy production in mammals and birds. In animal tissues the enzymes of fatty acid oxidation are located in the mitochondrion. Recent reports suggest that this is not the case in Castor bean endosperm. In this tissue the enzymes of B-oxid

  5. Hepatic fatty acid oxidation : activity, localization and function of some enzymes involved

    NARCIS (Netherlands)

    A. van Tol (Arie)

    1971-01-01

    textabstractFatty acid oxidation is an important pathway for energy production in mammals and birds. In animal tissues the enzymes of fatty acid oxidation are located in the mitochondrion. Recent reports suggest that this is not the case in Castor bean endosperm. In this tissue the enzymes of B-oxid

  6. Mitochondrial fatty acid oxidation alterations in heart failure, ischaemic heart disease and diabetic cardiomyopathy.

    Science.gov (United States)

    Fillmore, N; Mori, J; Lopaschuk, G D

    2014-04-01

    Heart disease is a leading cause of death worldwide. In many forms of heart disease, including heart failure, ischaemic heart disease and diabetic cardiomyopathies, changes in cardiac mitochondrial energy metabolism contribute to contractile dysfunction and to a decrease in cardiac efficiency. Specific metabolic changes include a relative increase in cardiac fatty acid oxidation rates and an uncoupling of glycolysis from glucose oxidation. In heart failure, overall mitochondrial oxidative metabolism can be impaired while, in ischaemic heart disease, energy production is impaired due to a limitation of oxygen supply. In both of these conditions, residual mitochondrial fatty acid oxidation dominates over mitochondrial glucose oxidation. In diabetes, the ratio of cardiac fatty acid oxidation to glucose oxidation also increases, although primarily due to an increase in fatty acid oxidation and an inhibition of glucose oxidation. Recent evidence suggests that therapeutically regulating cardiac energy metabolism by reducing fatty acid oxidation and/or increasing glucose oxidation can improve cardiac function of the ischaemic heart, the failing heart and in diabetic cardiomyopathies. In this article, we review the cardiac mitochondrial energy metabolic changes that occur in these forms of heart disease, what role alterations in mitochondrial fatty acid oxidation have in contributing to cardiac dysfunction and the potential for targeting fatty acid oxidation to treat these forms of heart disease.

  7. Common 894G>T single nucleotide polymorphism in the gene coding for endothelial nitric oxide synthase (eNOS) and risk of congenital heart defects

    NARCIS (Netherlands)

    Beynum, van I.M.; Mooij, C.; Kapusta, L.; Heil, S.G.; Heijer, den M.

    2008-01-01

    BACKGROUND: Endothelial nitric oxide synthase (eNOS) produces nitric oxide, which plays a role in vasodilatation and in the regulation of cell growth and apoptosis. eNOS-deficient mice have impaired cardiac development resulting in congenital heart defects (CHDs). In humans, a single nucleotide

  8. ANTIOXIDANT AND PRO-OXIDANT EFFECT OF ASCORBIC ACID

    Directory of Open Access Journals (Sweden)

    Goran Rankovic

    2005-01-01

    Full Text Available Free radicals attack proteins, lipids, enzymes and DNA causing pathological changes in organism. There are many mechanisms that organism uses to fight against free radicals. Ascorbic acid is one of the strongest reducers and eliminators of free radicals. It reduces stable oxygenic, azoth and thyol radicals and acts as a primary defense against water radicals in blood. When radicals are dissolved in water suspensions of erythrocytes and low density lipoproteins (LDL, ascorbic acid catches and eliminates free radicals before they arrive to the membrane and LDL molecules. Even though ascorbic acid is not capable of eliminating free radicals out of fluid medium, it acts as synergist to alpha-tocopherol in lipid section, contributes to the lessening of lipid tocoperoxil radicals, and above all, regenerates alpha-tocopherol. Ascorbic acid may act as pro-oxidant under in vitro conditions in the presence of metals; however, this effect is probably not important under in vivo conditions where metal ions, being sequestered, become second reducers.

  9. The stress-regulatory transcription factors Msn2 and Msn4 regulate fatty acid oxidation in budding yeast.

    Science.gov (United States)

    Rajvanshi, Praveen Kumar; Arya, Madhuri; Rajasekharan, Ram

    2017-09-18

    The transcription factors multicopy suppressor of SNF1 mutation (Msn) Msn2 and Msn4 bind the stress-response element in gene promoters in the yeast Saccharomyces cerevisiae. However, the roles of Msn2/4 in primary metabolic pathways such as fatty acid β-oxidation are unclear. Here, in silico analysis revealed that the promoters of most genes involved in the biogenesis, function, and regulation of the peroxisome contain Msn2/4 binding sites. We also found that transcript levels of MSN2/MSN4 are increased in glucose-depletion conditions and that during growth in nonpreferred carbon sources, Msn2 is constantly localized to the nucleus in wildtype cells. Of note, the double mutant msn2Δmsn4Δ exhibited a severe growth defect when grown with oleic acid as the sole carbon source and had reduced transcript levels of major β-oxidation genes. ChIP indicated that Msn2 has increased occupancy on the promoters of β-oxidation genes in glucose-depleted conditions, and in vivo reporter genes analysis indicated reduced expression of these genes in msn2Δmsn4Δ cells. Moreover, mobility shift assays revealed that Msn4 binds β-oxidation gene promoters. Immunofluorescence microscopy with anti-peroxisome membrane protein antibodies disclosed that the msn2Δmsn4Δ strain had fewer peroxisomes than the wildtype, and lipid analysis indicated that the msn2Δmsn4Δ strain had increased triacylglycerol and steryl ester levels. Collectively, our data suggest that Msn2/Msn4 transcription factors activate expression of the genes involved in fatty acid oxidation. As glucose sensing, signaling, and fatty acid β-oxidation pathways are evolutionarily conserved throughout eukaryotes, the msn2Δmsn4Δ strain could therefore be a good model system for further study of these critical processes. Copyright © 2017, The American Society for Biochemistry and Molecular Biology.

  10. Awareness and intake of folic acid for the prevention of neural tube defects among Lebanese women of childbearing age.

    Science.gov (United States)

    Nasr Hage, Claudine; Jalloul, Maya; Sabbah, Mohamad; Adib, Salim M

    2012-01-01

    Since the early 1990s, international recommendations have promoted folic acid supplementation during the periconception period as an effective way of preventing neural tube defects (NTDs). However, the adoption of this recommendation remains insufficient. To assess the awareness and actual intake of folic acid among married Lebanese women aged 18-45 years, a cross-sectional study was conducted among 600 women selected from all five administrative districts in Lebanon, using a multistage cluster sampling procedure. An anonymous questionnaire was completed which covered measures of knowledge and use of folate supplements, as well as demographic, socioeconomic and obstetrical factors. Sixty percent of surveyed women (60%; n = 360) had heard about folic acid. Doctors were the most frequent source of information (61.1%) but only 24.7% of women have been told of the correct period during which folic acid supplementation was useful. Overall, only 6.2% had taken folic acid tablets during the adequate period. Younger age, higher education level and stability/sufficiency of income appeared to be significant predictors of awareness among Lebanese women. Actual folic acid intake was significantly associated with younger age, higher number of pregnancies, planning the last pregnancy and having had that last one after 1990. In Lebanon, the level of folic acid awareness and adequate intake remain relatively low. Several approaches should be used to promote folic acid intake including awareness campaigns, and routine counseling by primary health care physicians on folic acid during preconception visits.

  11. The study of neural tube defects after the Human Genome Project and folic acid fortification of foods.

    Science.gov (United States)

    Graf, W D; Oleinik, O E

    2000-12-01

    The implementation of folic acid fortification will eliminate a proportion of neural tube defects (NTD). As a result, the etiologic and clinical profiles of the developmental disorder may both change. In the assessment of NTD as it evolves, the bioinformatics structure and content of the Human Genome Project will find vital application. One important development will be an enhanced understanding of the role of folic acid in global regulation of gene expression through epigenetic processes. In addition, bioinformatics will facilitate coordination of research in the basic sciences with clinical investigations to better define remaining etiologic factors.

  12. Ammonia-oxidizing archaea have more important role than ammonia-oxidizing bacteria in ammonia oxidation of strongly acidic soils.

    Science.gov (United States)

    Zhang, Li-Mei; Hu, Hang-Wei; Shen, Ju-Pei; He, Ji-Zheng

    2012-05-01

    Increasing evidence demonstrated the involvement of ammonia-oxidizing archaea (AOA) in the global nitrogen cycle, but the relative contributions of AOA and ammonia-oxidizing bacteria (AOB) to ammonia oxidation are still in debate. Previous studies suggest that AOA would be more adapted to ammonia-limited oligotrophic conditions, which seems to be favored by protonation of ammonia, turning into ammonium in low-pH environments. Here, we investigated the autotrophic nitrification activity of AOA and AOB in five strongly acidic soils (pHnitrification inhibitor dicyandiamide (DCD) completely inhibited the nitrification activity and CO(2) fixation by AOA, accompanied by decreasing thaumarchaeal amoA gene abundance. Bacterial amoA gene abundance decreased in all microcosms irrespective of DCD addition, and mostly showed no correlation with nitrate concentrations. Phylogenetic analysis of thaumarchaeal amoA gene and 16S rRNA gene revealed active (13)CO(2)-labeled AOA belonged to groups 1.1a-associated and 1.1b. Taken together, these results provided strong evidence that AOA have a more important role than AOB in autotrophic ammonia oxidation in strongly acidic soils.

  13. Evolution of insoluble eutectic Si particles in anodic oxidation films during adipic-sulfuric acid anodizing processes of ZL114A aluminum alloys

    Science.gov (United States)

    Hua, Lei; Liu, Jian-hua; Li, Song-mei; Yu, Mei; Wang, Lei; Cui, Yong-xin

    2015-03-01

    The effects of insoluble eutectic Si particles on the growth of anodic oxide films on ZL114A aluminum alloy substrates were investigated by optical microscopy (OM) and scanning electron microscopy (SEM). The anodic oxidation was performed at 25°C and a constant voltage of 15 V in a solution containing 50 g/L sulfuric acid and 10 g/L adipic acid. The thickness of the formed anodic oxidation film was approximately 7.13 μm. The interpore distance and the diameters of the major pores in the porous layer of the film were within the approximate ranges of 10-20 nm and 5-10 nm, respectively. Insoluble eutectic Si particles strongly influenced the morphology of the anodic oxidation films. The anodic oxidation films exhibited minimal defects and a uniform thickness on the ZL114A substrates; in contrast, when the front of the oxide oxidation films encountered eutectic Si particles, defects such as pits and non-uniform thickness were observed, and pits were observed in the films.

  14. Ruthenium-catalyzed aerobic oxidative decarboxylation of amino acids: a green, zero-waste route to biobased nitriles.

    Science.gov (United States)

    Claes, Laurens; Verduyckt, Jasper; Stassen, Ivo; Lagrain, Bert; De Vos, Dirk E

    2015-04-18

    Oxidative decarboxylation of amino acids into nitriles was performed using molecular oxygen as terminal oxidant and a heterogeneous ruthenium hydroxide-based catalyst. A range of amino acids was oxidized in very good yield, using water as the solvent.

  15. Folic acid in the prevention of neural tube defects: awareness among laywomen and healthcare providers in Japan.

    Science.gov (United States)

    Kondo, Atsuo; Yamamoto, Shin-ichi; Inoue, Hiromi; Watanabe, Junichiro; Tada, Katsuhiko; Yoshimoto, Nobuko

    2009-09-01

    It is known that neural tube defects are folic acid preventable congenital anomalies. We investigated to what extent this information was disseminated among laywomen and healthcare providers. Questionnaire studies were conducted twice, in 2002 and 2007, for four groups of laywomen and seven groups of healthcare providers in Japan regarding awareness, folic acid supplements and healthy diets. Awareness among laywomen was less than 20%, except for families who had experience with spina bifida in 2002, and 5 years later only pregnant women showed a significant increase in awareness. Awareness among healthcare providers varied from 12 to 76%, depending on their profession, and this proportion increased in five of the seven groups in 2007. The majority of laywomen obtained their information from mass media, while the majority of healthcare providers received information through media for professionals. Laywomen who used folate supplements and healthcare providers who recommended them were initially fewer than 25 and 37%, respectively. Five years later, however, pregnant women who used folic acid supplements increased from 9.1 to 43.1%. As awareness among non-pregnant laywomen and some healthcare providers is considerably low, information should be presented repeatedly to these groups. The difficulty in getting women to consume folic acid supplements is an argument for the government to require folic acid fortification of grains so that the prevention of neural tube defects can be maximized.

  16. Cyanide-insensitive and clofibrate enhanced beta-oxidation of dodecanedioic acid in rat liver. An indication of peroxisomal beta-oxidation of N-dicarboxylic acids.

    Science.gov (United States)

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

    1982-11-12

    The beta-oxidation rate of dodecanedioic acid in rat liver homogenates (600 X g supernatant fraction) was determined by simultaneous measurements of the C6-C12-dicarboxylic acids, i.e., adipic, suberic, sebacic and dodecanedioic acids, in relation to time in assays incubated with dodecanedioic acid. Measurements were performed by a combined gas chromatographic-mass spectrometric technique, i.e., selected ion-monitoring. The beta-oxidation rate was registered as the consumption rate of dodecanedioic acid and as the initial rise in the concentrations of C6-C10-dicarboxylic acids. The beta-oxidation rate of C8-C12-dicarboxylic acids was increased many times in homogenates from clofibrate-treated rats. Moreover, it was unexpectedly found that 2.0 mM cyanide was unable to inhibit the beta-oxidation rate of the dicarboxylic acids in vitro, but in fact caused a minor increase in the rate of beta-oxidation in homogenates from both normal and clofibrate-treated rats. It was concluded that the present results strongly indicate the existence of a peroxisomal beta-oxidation of dicarboxylic acids.

  17. Lewis acid catalysis and Green oxidations: sequential tandem oxidation processes induced by Mn-hyperaccumulating plants.

    Science.gov (United States)

    Escande, Vincent; Renard, Brice-Loïc; Grison, Claude

    2015-04-01

    Among the phytotechnologies used for the reclamation of degraded mining sites, phytoextraction aims to diminish the concentration of polluting elements in contaminated soils. However, the biomass resulting from the phytoextraction processes (highly enriched in polluting elements) is too often considered as a problematic waste. The manganese-enriched biomass derived from native Mn-hyperaccumulating plants of New Caledonia was presented here as a valuable source of metallic elements of high interest in chemical catalysis. The preparation of the catalyst Eco-Mn1 and reagent Eco-Mn2 derived from Grevillea exul exul and Grevillea exul rubiginosa was investigated. Their unusual polymetallic compositions allowed to explore new reactivity of low oxidative state of manganese-Mn(II) for Eco-Mn1 and Mn(IV) for Eco-Mn2. Eco-Mn1 was used as a Lewis acid to catalyze the acetalization/elimination of aldehydes into enol ethers with high yields; a new green and stereoselective synthesis of (-)-isopulegol via the carbonyl-ene cyclization of (+)-citronellal was also performed with Eco-Mn1. Eco-Mn2 was used as a mild oxidative reagent and controlled the oxidation of aliphatic alcohols into aldehydes with quantitative yields. Oxidative cleavage was interestingly noticed when Eco-Mn2 was used in the presence of a polyol. Eco-Mn2 allowed direct oxidative iodination of ketones without using iodine, which is strongly discouraged by new environmental legislations. Finally, the combination of the properties in the Eco-Mn catalysts and reagents gave them an unprecedented potential to perform sequential tandem oxidation processes through new green syntheses of p-cymene from (-)-isopulegol and (+)-citronellal; and a new green synthesis of functionalized pyridines by in situ oxidation of 1,4-dihydropyridines.

  18. Role of silver doping on the defects related photoluminescence and antibacterial behaviour of zinc oxide nanoparticles.

    Science.gov (United States)

    Kumar, Vinod; Prakash, Jai; Singh, Jitendra Pal; Chae, Keun Hwa; Swart, C; Ntwaeaborwa, O M; Swart, H C; Dutta, Viresh

    2017-07-29

    The Ag doped ZnO (ZnO:Ag) NPs with a hexagonal wurtzite structure were synthesized by a solution combustion method. X-ray absorption near edge structure (XANES) and X-ray photoelectron spectroscopy (XPS) were used to study the defects, local electronic and atomic structures before and after Ag doping. XPS and XANES studies confirmed the deficiency of concentration of defects in ZnO after Ag doping. The photoluminescence study showed the deep level emission in the orange-red region in addition to the band to band emission. It was also found that the defect related emission of ZnO was decreased with an increasing in Ag concentration. The antibacterial behaviour of ZnO and ZnO:Ag NPs was studied against the gram positive and gram negative bacteria. The role of Ag doping and defects in the ZnO NPs were discussed for the observed antibacterial and photoluminescence behaviour. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. ω-Alkynyl lipid surrogates for polyunsaturated fatty acids: free radical and enzymatic oxidations.

    Science.gov (United States)

    Beavers, William N; Serwa, Remigiusz; Shimozu, Yuki; Tallman, Keri A; Vaught, Melissa; Dalvie, Esha D; Marnett, Lawrence J; Porter, Ned A

    2014-08-13

    Lipid and lipid metabolite profiling are important parameters in understanding the pathogenesis of many diseases. Alkynylated polyunsaturated fatty acids are potentially useful probes for tracking the fate of fatty acid metabolites. The nonenzymatic and enzymatic oxidations of ω-alkynyl linoleic acid and ω-alkynyl arachidonic acid were compared to that of linoleic and arachidonic acid. There was no detectable difference in the primary products of nonenzymatic oxidation, which comprised cis,trans-hydroxy fatty acids. Similar hydroxy fatty acid products were formed when ω-alkynyl linoleic acid and ω-alkynyl arachidonic acid were reacted with lipoxygenase enzymes that introduce oxygen at different positions in the carbon chains. The rates of oxidation of ω-alkynylated fatty acids were reduced compared to those of the natural fatty acids. Cyclooxygenase-1 and -2 did not oxidize alkynyl linoleic but efficiently oxidized alkynyl arachidonic acid. The products were identified as alkynyl 11-hydroxy-eicosatetraenoic acid, alkynyl 11-hydroxy-8,9-epoxy-eicosatrienoic acid, and alkynyl prostaglandins. This deviation from the metabolic profile of arachidonic acid may limit the utility of alkynyl arachidonic acid in the tracking of cyclooxygenase-based lipid oxidation. The formation of alkynyl 11-hydroxy-8,9-epoxy-eicosatrienoic acid compared to alkynyl prostaglandins suggests that the ω-alkyne group causes a conformational change in the fatty acid bound to the enzyme, which reduces the efficiency of cyclization of dioxalanyl intermediates to endoperoxide intermediates. Overall, ω-alkynyl linoleic acid and ω-alkynyl arachidonic acid appear to be metabolically competent surrogates for tracking the fate of polyunsaturated fatty acids when looking at models involving autoxidation and oxidation by lipoxygenases.

  20. [Experimental study of poly-DL-lactic acid membrane guided bone regeneration in rabbit radii bone defects].

    Science.gov (United States)

    Duan, Hong; Fan, Yubo; Dou, Jun; Pei, Fuxing

    2004-10-01

    This study was conducted to observe bone regeneration guided by poly-DL-latic acid (PDLLA) membrane in rabbit radii bone defects and to explore the mechanism of the membrane guided bone regeneration (MGBR). The animal models of bony and periosteous defects were established in both radii of 40 adult New Zealand white rabbits. The left defect as the experimental side was bridged with PDLLA membrane tube, the right side as the controlled side was untreated. The specimens were collected at 2, 4, 8 and 12 weeks postoperatively. General observation, X-ray, histological observation and biomechanical examination were applied to the repair of the models of MGBR in both groups. Two weeks after operation, with much new bony callus formed outside the tube at both fragments, the membrane tube covered with connective tissues was filled with haematoma and fibrous callus. Twelve weeks after operation, the PDLLA membrane became white and its tube shape was still maintained. However, new bone callus outside the tube almost completely disappeared, and inside the tubes all radii bone defects were successfully repaired with bony union. On the controlled sides, bone defects were filled with connective tissues 2 weeks postoperatively. And 12 weeks after operation, the typical nonunion that had been formed after bone marrow canals were sealed with cortical bone. On the experimental side, the strength of the newly formed bone at the 12th week was higher than that at the 8th week (Pregeneration could be successfully guided by PDLLA membrane, and this MGBR technique might be generally used in the treatment of bone defects and nonunion.

  1. Arabidopsis thaliana cdd1 mutant uncouples the constitutive activation of salicylic acid signalling from growth defects

    NARCIS (Netherlands)

    Swain, S.; Roy, S.; Shah, J.; Wees, S.C.M. van; Pieterse, C.M.J.; Nandi, A.K.

    2011-01-01

    Arabidopsis genotypes with a hyperactive salicylic acidmediated signalling pathway exhibit enhanced disease resistance, which is often coupled with growth and developmental defects, such as dwarfing and spontaneous necrotic lesions on the leaves, resulting in reduced biomass yield. In this article,

  2. Electrocatalysis by nanoparticles: Oxidation of formic acid at manganese oxide nanorods-modified Pt planar and nanohole-arrays

    Directory of Open Access Journals (Sweden)

    Mohamed S. El-Deab

    2010-01-01

    Full Text Available The electro-oxidation of formic acid (an essential reaction in direct formic acid fuel cells is a challenging process because of the deactivation of anodes by the adsorption of the poisoning intermediate carbon monoxide (CO. Pt electrodes in two geometries (planar and nanohole-array were modified by the electrodeposition of manganese oxide nanorods (nano-MnOx. The modified Pt electrodes were then tested for their electrocatalytic activity through the electro-oxidation of formic acid in a solution of pH 3.45. Two oxidation peaks (Ipd and Ipind were observed at 0.2 and 0.55 V, respectively; these were assigned to the direct and indirect oxidative pathways. A significant enhancement of the direct oxidation of formic acid to CO2 was observed at the modified electrodes, while the formation of the poisoning intermediate CO was suppressed. Ipd increases with surface coverage (θ of nano-MnOx with a concurrent depression of Ipind. An increase in the ratio Ipd/ν1/2 with decreasing potential scan rate (ν indicates that the oxidation process proceeds via a catalytic mechanism. The modification of Pt anodes with manganese oxide nanorods results in a significant improvement of the electrocatalytic activity along with a higher tolerance to CO. Thus nano-MnOx plays a crucial role as a catalytic mediator which facilitates the charge transfer during the direct oxidation of formic acid to CO2.

  3. Oxidative aromatization of Hantzsch 1,4-dihydropyridines by aqueous hydrogen peroxide-acetic acid

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A simple method for the oxidative aromatization of Hantzsch 1,4-dihydropyridines to the corresponding pyridines is achieved by using hydrogen peroxide as green oxidant and acetic acid as catalyst in aqueous solution.

  4. The association between low-grade inflammation, iron status and nucleic acid oxidation in the elderly

    DEFF Research Database (Denmark)

    Broedbaek, Kasper; Siersma, Volkert Dirk; Andersen, Jon T

    2011-01-01

    This study applied a case-control approach to investigate the association between low-grade inflammation, defined by high values within the normal range of C-reactive protein (CRP) and interleukin-6 (IL-6), and urinary markers of nucleic acid oxidation. No differences in excretion of urinary...... markers of nucleic acid oxidation between cases and controls were found and multivariable linear regression analysis showed no association between urinary markers of nucleic acid oxidation and inflammatory markers. Post-hoc multivariable linear regression analysis showed significant associations between...... nucleic acid oxidation and various iron status markers and especially a close relationship between nucleic acid oxidation and ferritin. This study shows no association between low-grade inflammation and urinary markers of nucleic acid oxidation in a population of elderly Italian people. The results...

  5. Defect-induced loading of Pt nanoparticles on carbon nanotubes

    Science.gov (United States)

    Kim, Sung Jin; Park, Yong Jin; Ra, Eun Ju; Kim, Ki Kang; An, Kay Hyeok; Lee, Young Hee; Choi, Jae Young; Park, Chan Ho; Doo, Seok Kwang; Park, Min Ho; Yang, Cheol Woong

    2007-01-01

    Carbon nanotubes-supported Pt nanoparticles were loaded using a microwave oven on the defective carbon nanotubes generated by an additional oxidant during acid treatment. The authors' Raman spectra and x-ray diffraction analysis demonstrated that defects created during oxidation and microwave treatment acted as nucleation seeds for Pt adsorption. The generated Pt nanoparticles had the size distributions of 2-3nm and were uniformly distributed on the defects of carbon nanotubes. The authors' density functional calculations showed that the adsorption of Pt atom on the vacancy of nanotube was significantly stronger by s-p hybridization with carbon atoms near the defect site.

  6. Measurement of fatty acid oxidation: validation of isotopic equilibrium extrapolation

    Energy Technology Data Exchange (ETDEWEB)

    Robin, A.P.; Jeevanandam, M.; Elwyn, D.H.; Askanazi, J.; Kinney, J.M.

    1989-01-01

    Measurement of whole body substrate oxidation requires prolonged isotope infusion to attain plateau specific activity (SA) of expired CO/sub 2/. We have investigated in 13 hospitalized patients a technique whereby plateau /sup 14/CO/sub 2/ SA is extrapolated using computer curve fitting based upon the early exponential rise. A primed-constant infusion of albumin-bound 1-/sup 14/C-palmitate was continued for 260 minutes with isotope priming of the secondary bicarbonate pool at 70 minutes. Plasma free fatty acid (FFA) SA reached steady state by 40 minutes and was 91% +/- 4% (SE) of values obtained at 190 to 260 minutes. At 70 minutes /sup 14/CO/sub 2/ SA reached only 44% +/- 1% of the 190 to 260 minute values, which were consistently at plateau. The predicted steady state /sup 14/CO/sub 2/ SA from the 40 to 70 minute curves and the FFA oxidation rates calculated from those values were 94% +/- 2% and 102% +/- 4%, respectively, of values measured at steady state (190 to 260 minutes). The relationship between predicted and measured values approximated the line of identity for /sup 14/CO/sub 2/ SA (y = 0.90x + 0.14, r = .98, P less than .001) and FFA oxidation (y = 1.02x, r = .98, P less than .001). The results suggest that FFA oxidation can be accurately calculated using a short infusion of labeled FFA without bicarbonate pool priming, thus avoiding overpriming or underpriming and possibly allowing multiple studies and diminished radioisotope exposure.

  7. In vitro targeted magnetic delivery and tracking of superparamagnetic iron oxide particles labeled stem cells for articular cartilage defect repair.

    Science.gov (United States)

    Feng, Yong; Jin, Xuhong; Dai, Gang; Liu, Jun; Chen, Jiarong; Yang, Liu

    2011-04-01

    To assess a novel cell manipulation technique of tissue engineering with respect to its ability to augment superparamagnetic iron oxide particles (SPIO) labeled mesenchymal stem cells (MSCs) density at a localized cartilage defect site in an in vitro phantom by applying magnetic force. Meanwhile, non-invasive imaging techniques were use to track SPIO-labeled MSCs by magnetic resonance imaging (MRI). Human bone marrow MSCs were cultured and labeled with SPIO. Fresh degenerated human osteochondral fragments were obtained during total knee arthroplasty and a cartilage defect was created at the center. Then, the osteochondral fragments were attached to the sidewalls of culture flasks filled with phosphate-buffered saline (PBS) to mimic the human joint cavity. The SPIO-labeled MSCs were injected into the culture flasks in the presence of a 0.57 Tesla (T) magnetic force. Before and 90 min after cell targeting, the specimens underwent T2-weighted turbo spin-echo (SET2WI) sequence of 3.0 T MRI. MRI results were compared with histological findings. Macroscopic observation showed that SPIO-labeled MSCs were steered to the target region of cartilage defect. MRI revealed significant changes in signal intensity (P<0.01). HE staining exibited that a great number of MSCs formed a three-dimensional (3D) cell "sheet" structure at the chondral defect site. It was concluded that 0.57 T magnetic force permits spatial delivery of magnetically labeled MSCs to the target region in vitro. High-field MRI can serve as an very sensitive non-invasive technique for the visualization of SPIO-labeled MSCs.

  8. The rationale for preventing cancer cachexia: targeting excessive fatty acid oxidation

    OpenAIRE

    2016-01-01

    Cachexia commonly occurs at the terminal stage of cancer and has largely unclear molecular mechanisms. A recent study published in Nature Medicine, entitled “Excessive fatty acid oxidation induces muscle atrophy in cancer cachexia,” reveals that cachectic cancer cells can secrete multiple cytokines that induce excessive fatty acid oxidation, which is responsible for muscle loss in cancer cachexia. Inhibition of fatty acid oxidation using etomoxir can increase muscle mass and body weight in ca...

  9. Kinetics and mechanism of the oxidation of formic and oxalic acids by benzyltrimethylammonium dichloroiodate

    Indian Academy of Sciences (India)

    Poonam Gupta; Seema Kothari

    2001-04-01

    The oxidation of formic and oxalic acids by benzyltrimethylammonium dichloroiodate (BTMACI), in the presence of zinc chloride, leads to the formation of carbon dioxide. The reaction is first order with respect to BTMACI, zinc chloride and organic acid. Oxidation of deuteriated formic acid indicates the presence of a kinetic isotope effect. Addition of benzyltrimethylammonium chloride enhances the rate. It is proposed that the reactive oxidizing species is [(PhCH2Me3N)+ (IZn2Cl6)−]. Suitablemechanisms have been proposed.

  10. Protective effect of periconceptional folic acid supplements on the risk of congenital heart defects: a registry-based case-control study in the northern Netherlands.

    NARCIS (Netherlands)

    Beijnum, I.M. van; Kapusta, L.; Bakker, M.K.; Heijer, M. den; Blom, H.J.; Walle, H.E. de

    2010-01-01

    AIMS: To investigate the potentially protective of periconceptional folic acid use on the risk of congenital heart defects (CHDs) relative to other non-folate related malformations. METHODS AND RESULTS: We analysed data from a large regional register of birth defects (EUROCAT-Northern Netherlands),

  11. Protective effect of periconceptional folic acid supplements on the risk of congenital heart defects : a registry-based case-control study in the northern Netherlands

    NARCIS (Netherlands)

    van Beynum, Ingrid M.; Kapusta, Livia; Bakker, Marian K.; den Heijer, Martin; Blom, Henk J.; de Walle, Hermien E. K.

    2010-01-01

    To investigate the potentially protective of periconceptional folic acid use on the risk of congenital heart defects (CHDs) relative to other non-folate related malformations. We analysed data from a large regional register of birth defects (EUROCAT-Northern Netherlands), over a 10 year period (1996

  12. Protective effect of periconceptional folic acid supplements on the risk of congenital heart defects: a registry-based case-control study in the northern Netherlands.

    NARCIS (Netherlands)

    Beijnum, I.M. van; Kapusta, L.; Bakker, M.K.; Heijer, M. den; Blom, H.J.; Walle, H.E. de

    2010-01-01

    AIMS: To investigate the potentially protective of periconceptional folic acid use on the risk of congenital heart defects (CHDs) relative to other non-folate related malformations. METHODS AND RESULTS: We analysed data from a large regional register of birth defects (EUROCAT-Northern Netherlands),

  13. Protective effect of periconceptional folic acid supplements on the risk of congenital heart defects : a registry-based case-control study in the northern Netherlands

    NARCIS (Netherlands)

    van Beynum, Ingrid M.; Kapusta, Livia; Bakker, Marian K.; den Heijer, Martin; Blom, Henk J.; de Walle, Hermien E. K.

    To investigate the potentially protective of periconceptional folic acid use on the risk of congenital heart defects (CHDs) relative to other non-folate related malformations. We analysed data from a large regional register of birth defects (EUROCAT-Northern Netherlands), over a 10 year period

  14. THE INFLUENCE OF NIOBIUM ON THE ACIDITY AND STRUCTURE OF GAMMA-ALUMINA-SUPPORTED VANADIUM OXIDES

    Directory of Open Access Journals (Sweden)

    M.N.B. Sathler

    1998-06-01

    Full Text Available Gamma-alumina-supported niobium oxide was used as a support for vanadium oxides. The influence of the addition of niobium oxide was studied by looking for changes in the structure and acid-base character of superficial species. Vanadium oxide was deposited using the continuous adsorption method; niobium oxide was impregnated using the incipient wetness method. The catalysts were characterized by XPS, UV-visible and IR spectroscopy. Catalytic tests were performed using propane oxidation reaction at 400oC. For coverage below the monolayer, both vanadium and niobium oxides were observed in slightly condensed superficial species. The presence of vanadium oxide on the support was found to increase the Lewis acidity and create some Bronsted acidity. Higher catalytic activity and selectivity for propene were associated with vanadium oxides. The presence of niobium did not contribute to the modification of the chemical properties of superficial vanadium but did decrease the adsorption of vanadium on the alumina.

  15. Kinetics of oxidation of acidic amino acids by sodium N-bromobenzenesulphonamide in acid medium: A mechanistic approach

    Indian Academy of Sciences (India)

    Puttaswamy; Nirmala Vaz

    2001-08-01

    Kinetics of oxidation of acidic amino acids (glutamic acid (Glu) and aspartic acid (Asp)) by sodium N-bromobenzenesulphonamide (bromamine-B or BAB) has been carried out in aqueous HClO4 medium at 30°C. The rate shows firstorder dependence each on [BAB]o and [amino acid]o and inverse first-order on [H+]. At [H+] > 0 60 mol dm-3, the rate levelled off indicating zero-order dependence on [H+] and, under these conditions, the rate has fractional order dependence on [amino acid]. Succinic and malonic acids have been identified as the products. Variation of ionic strength and addition of the reaction product benzenesulphonamide or halide ions had no significant effect on the reaction rate. There is positive effect of dielectric constant of the solvent. Proton inventory studies in H2O-D2O mixtures showed the involvement of a single exchangeable proton of the OH- ion in the transition state. Kinetic investigations have revealed that the order of reactivity is Asp > Glu. The rate laws proposed and derived in agreement with experimental results are discussed.

  16. IDH1 mutations alter citric acid cycle metabolism and increase dependence on oxidative mitochondrial metabolism

    National Research Council Canada - National Science Library

    Grassian, Alexandra R; Parker, Seth J; Davidson, Shawn M; Divakaruni, Ajit S; Green, Courtney R; Zhang, Xiamei; Slocum, Kelly L; Pu, Minying; Lin, Fallon; Vickers, Chad; Joud-Caldwell, Carol; Chung, Franklin; Yin, Hong; Handly, Erika D; Straub, Christopher; Growney, Joseph D; Vander Heiden, Matthew G; Murphy, Anne N; Pagliarini, Raymond; Metallo, Christian M

    2014-01-01

    .... We observed that under hypoxic conditions, IDH1-mutant cells exhibited increased oxidative tricarboxylic acid metabolism along with decreased reductive glutamine metabolism, but not IDH2-mutant cells...

  17. Inhibition of oxidative metabolism by propionic acid and its reversal by carnitine in isolated rat hepatocytes.

    Science.gov (United States)

    Brass, E P; Fennessey, P V; Miller, L V

    1986-01-01

    The present study was designed to study the interaction of propionic acid and carnitine on oxidative metabolism by isolated rat hepatocytes. Propionic acid (10 mM) inhibited hepatocyte oxidation of [1-14C]-pyruvate (10 mM) by 60%. This inhibition was not the result of substrate competition, as butyric acid had minimal effects on pyruvate oxidation. Carnitine had a small inhibitory effect on pyruvate oxidation in the hepatocyte system (210 +/- 19 and 184 +/- 18 nmol of pyruvate/60 min per mg of protein in the absence and presence of 10 mM-carnitine respectively; means +/- S.E.M., n = 10). However, in the presence of propionic acid (10 mM), carnitine (10 mM) increased the rate of pyruvate oxidation by 19%. Under conditions where carnitine partially reversed the inhibitory effect of propionic acid on pyruvate oxidation, formation of propionylcarnitine was documented by using fast-atom-bombardment mass spectroscopy. Propionic acid also inhibited oxidation of [1-14C]palmitic acid (0.8 mM) by hepatocytes isolated from fed rats. The degree of inhibition caused by propionic acid was decreased in the presence of 10 mM-carnitine (41% inhibition in the absence of carnitine, 22% inhibition in the presence of carnitine). Propionic acid did not inhibit [1-14C]palmitic acid oxidation by hepatocytes isolated from 48 h-starved rats. These results demonstrate that propionic acid interferes with oxidative metabolism in intact hepatocytes. Carnitine partially reverses the inhibition of pyruvate and palmitic acid oxidation by propionic acid, and this reversal is associated with increased propionylcarnitine formation. The present study provides a metabolic basis for the efficacy of carnitine in patients with abnormal organic acid accumulation, and the observation that such patients appear to have increased carnitine requirements ('carnitine insufficiency'). PMID:3790065

  18. Defect mediated reversible ferromagnetism in Co and Mn doped zinc oxide epitaxial films

    Energy Technology Data Exchange (ETDEWEB)

    Mal, Siddhartha; Nori, Sudhakar; Narayan, J. [Department of Material Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Mula, Suhrit [Department of Material Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Department of Metallurgical and Materials Engineering, National Institute of Technology, Rourkela 769008 (India); Prater, J. T. [Materials Science Division, Army Research Office, Research Triangle Park, North Carolina 27709 (United States)

    2012-12-01

    We have introduced defects in ZnO (undoped and doped with Co and Mn) epitaxial thin films using laser irradiation from nanosecond laser pulses and thermal annealing in oxygen ambient. In contrast to the as grown samples, the laser irradiated films show a significant increase in conductivity, enhancement in UV emission, while maintaining the same wurtzite crystal structure. Room-temperature ferromagnetism (RTFM) is observed in laser-irradiated samples, which increased with the number of laser pulses up to a certain value where magnetic moment saturates. The induced ferromagnetism as well as the enhanced electrical conductivity can be reversed with thermal annealing in oxygen ambient. The magnetization in Co and Mn doped films was found to be strong function of growth conditions and defect concentration. X-ray diffraction and optical absorption experiments suggested a 2+ valance state and tetrahedral coordination for both Co and Mn ions. There is a simultaneous increase in n-type electrical conductivity with the number of laser pulses and continue to exhibit semiconducting behavior in both undoped and doped films. The saturation magnetization was found to be 0.08 {mu}{sub B}/Co and 0.05 {mu}{sub B}/Mn, much lower than 3.0 {mu}{sub B}/Co and 5.0 {mu}{sub B}/Mn, indicating the prominent role of intrinsic defects in RTFM with some contribution from Co{sup 2+}-oxygen vacancy complexes. We propose a unified mechanism based upon introduction of intrinsic defects to explain RTFM and n-type conductivity enhancements during pulsed laser and thermal annealing.

  19. Oxidation states of molybdenum in oxide films formed in sulphuric acid and sodium hydroxide

    Energy Technology Data Exchange (ETDEWEB)

    Okonkwo, I.A.; Doff, J.; Baron-Wiechec, A. [Corrosion and Protection Centre, School of Materials, The University of Manchester, Manchester M13 9PL (United Kingdom); Jones, G. [Waters Corporation, Floats Rd, Roundthorn Ind. Est., Manchester M23 9LZ (United Kingdom); Koroleva, E.V. [Corrosion and Protection Centre, School of Materials, The University of Manchester, Manchester M13 9PL (United Kingdom); Skeldon, P., E-mail: p.skeldon@manchester.ac.uk [Corrosion and Protection Centre, School of Materials, The University of Manchester, Manchester M13 9PL (United Kingdom); Thompson, G.E. [Corrosion and Protection Centre, School of Materials, The University of Manchester, Manchester M13 9PL (United Kingdom)

    2012-07-31

    X-ray photoelectron spectroscopy is used to investigate the oxidation states of molybdenum in thin films formed potentiostatically, over a range of potentials, in either 1 mol dm{sup -3} H{sub 2}SO{sub 4} or 10 mol dm{sup -3} NaOH at 20 Degree-Sign C. Mo 3d spectra suggested that MoO{sub 2} and Mo(OH){sub 2} were the main components of the films, with smaller amounts of MoO{sub 3} and possibly Mo{sub 2}O{sub 5}. O 1s spectra indicated the presence of oxygen as oxide and hydroxide species and as bound water. Ion beam analysis revealed the formation of thin films at all potentials, with significant losses of oxidized molybdenum to the electrolyte. - Highlights: Black-Right-Pointing-Pointer Oxides are formed on molybdenum in sulphuric acid and sodium hydroxide solutions. Black-Right-Pointing-Pointer Molybdenum IV and VI are identified by XPS, with MoO2 species dominating. Black-Right-Pointing-Pointer Thicknesses of films are determined by ion beam analysis for a range of potentials. Black-Right-Pointing-Pointer Films form at low efficiency due to loss of molybdenum species to electrolyte.

  20. Repair of rat cranial bone defect by using bone morphogenetic protein-2-related peptide combined with microspheres composed of polylactic acid/polyglycolic acid copolymer and chitosan.

    Science.gov (United States)

    Li, Jingfeng; Jin, Lin; Wang, Mingbo; Zhu, Shaobo; Xu, Shuyun

    2015-07-08

    The effects of the transplanted bone morphogenetic protein-2 (BMP2) -related peptide P24 and rhBMP2 combined with poly(lactic-co-glycolic acid) (PLGA)/chitosan (CS) microspheres were investigated in promoting the repair of rat cranial bone defect. Forty white rats were selected and equally divided into four groups (group A: 1 μg of rhBMP2/PLGA/CS composite; group B: 3 mg of P24/PLGA/CS composite; group C: 0.5 μg of rhBMP2 + 1.5 mg of P24/PLGA/CS composite; group D: blank PLGA/CS material), and rat cranial bone defect models with a diameter of 5 mm were established. The materials were transplanted to the cranial bone defects. The animals were sacrificed on weeks 6 and 12 post-operation. Radiographic examinations (x-ray imaging and 3D CT scanning) and histological evaluations were performed. The repaired areas of cranial bone defects were measured, and the osteogenetic abilities of various materials were compared. Cranial histology, imaging, and repaired area measurements showed that the osteogenetic effects at two time points (weeks 6 and 12) in group C were better than those in groups A and B. The effects in groups A and B were similar. Group D achieved the worst repair effect of cranial bone defects, where a large number of fibrous connective tissues were observed. The PLGA/CS composite microspheres loaded with rhBMP2 and P24 had optimal concrescence and could mutually increase their osteogenesis capability. rhBMP2 + P24/PLGA/CS composite is a novel material for bone defect repair with stable activity to induce bone formation.

  1. Structural and optical investigations of oxygen defects in zinc oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Sahai, Anshuman; Goswami, Navendu, E-mail: navendugoswami@gmail.com [Department of Physics and Materials Science and Engineering, Jaypee Institute of Information Technology, A-10, Sec. 62, Noida. (U.P.)-201307 (India)

    2015-06-24

    ZnO nanoparticles (NPs) were prepared implementing chemical precipitation method. Structural and optical characterizations of synthesized ZnO NPs were thoroughly probed applying X-ray diffraction (XRD), transmission electron microscope (TEM), energy dispersive X-ray (EDX) analysis, X-ray photoelectron spectroscopy (XPS), UV- Visible absorption and fluorescence (FL) spectroscopy. The XRD and TEM analyses revealed hexagonal wurtzite phase with 25-30 nm size. EDX analysis indicated oxygen (O) rich composition of nanoparticles. In accordance with EDX, XPS analysis verifies O{sub i} rich stoichiometry of prepared NPs. Furthermore, concurrence of lattice oxygen (O{sub L}), interstitial oxygen (O{sub i}) and oxygen vacancy (V{sub O}) in ZnO NPs was demonstrated through XPS analysis. Size quantization of nanoparticles is evident by blue shift of UV-Visible absorption energy. The FL spectroscopic investigations ascertain the existence of several discrete and defect states and radiative transitions occurring therein. Display of visible emission from oxygen defect states and most importantly, excess of O{sub i} defects in prepared ZnO nanoparticles, was well established through FL study.

  2. Structural and optical investigations of oxygen defects in zinc oxide nanoparticles

    Science.gov (United States)

    Sahai, Anshuman; Goswami, Navendu

    2015-06-01

    ZnO nanoparticles (NPs) were prepared implementing chemical precipitation method. Structural and optical characterizations of synthesized ZnO NPs were thoroughly probed applying X-ray diffraction (XRD), transmission electron microscope (TEM), energy dispersive X-ray (EDX) analysis, X-ray photoelectron spectroscopy (XPS), UV- Visible absorption and fluorescence (FL) spectroscopy. The XRD and TEM analyses revealed hexagonal wurtzite phase with 25-30 nm size. EDX analysis indicated oxygen (O) rich composition of nanoparticles. In accordance with EDX, XPS analysis verifies Oi rich stoichiometry of prepared NPs. Furthermore, concurrence of lattice oxygen (OL), interstitial oxygen (Oi) and oxygen vacancy (VO) in ZnO NPs was demonstrated through XPS analysis. Size quantization of nanoparticles is evident by blue shift of UV-Visible absorption energy. The FL spectroscopic investigations ascertain the existence of several discrete and defect states and radiative transitions occurring therein. Display of visible emission from oxygen defect states and most importantly, excess of Oi defects in prepared ZnO nanoparticles, was well established through FL study.

  3. Awareness of folic acid for prevention of neural tube defects in a community with high prevalence of consanguineous marriages.

    Science.gov (United States)

    Jaber, Lutfi; Karim, Igbaria A; Jawdat, Abu Moch; Fausi, Mawasi; Merlob, Paul

    2004-01-01

    Neural tube defects (NTDs) are severe congenital malformations and can be fatal. Intake of 0.4 mg folic in the periconceptional period reduces the risk of NTD by 50-70%. Consanguinity in the Arab population in Israel is a prevalent custom. The aim of this study was to assess the level of awareness regarding folic acid and its effect in the prevention of NTD among Arab Israeli women of childbearing age. We conducted a cross-sectional study. Of the 653 women (18-45 years) who were randomly selected for interview while visiting their family physician or well-baby clinic, 624 women completed the questionnaire. Fifty-three percent (n = 333) of the respondents had heard of folic acid; 14% (n = 89) were familiar with the protective effect of NTD and 3% (n = 18) had taken folic acid in the first months of pregnancy whereas none of them had used it in the preconception period. Highly educated women, women with one or two children, paramedics, and women of high socioeconomic status were more knowledgeable about the protective effects of folic acid (P awareness of this population to the protective effect of folic acid. Daily supplementation and fertification of food with folic acid should be considered as the best way to improve the balance of folic acid in women of childbearing age of this special population (high prevalence of consanguinity).

  4. Folic acid and prevention of neural tube defects in 2000 improved awareness--low peri-conceptional uptake.

    Science.gov (United States)

    Oleary, M; Donnell, R M; Johnson, H

    2001-06-01

    Eight years have passed since recommendations were made by the Irish Department of Health on the importance of folic acid in the prevention of neural tube defects (NTD). There is currently no mandatory fortification of foodstuffs with folic acid in Ireland, with reliance placed on campaigns promoting increased dietary folate intake and supplements. We assessed knowledge and use of folic acid among 300 women attending ante-natal clinics in Dublin maternity hospitals in the year 2000 using an interviewer administered questionnaire. Qualitative information was obtained through means of a focus group. Ninety two percent of respondents had heard of folic acid and 67% knew it could prevent NTD. Thirty per cent were advised to take it peri-conceptionally but overall only 18% did so; 39% of women had planned their pregnancy. The focus group indicated that folic acid was not 'visible' enough and that fortification of food was more realistic. This study shows that improved folic acid awareness has not been accompanied by corresponding peri-conceptional uptake in 2000. Folic acid promotional campaigns should be continuous and targeted. Mandatory food fortification should be strongly considered.

  5. [Folic acid reduces the risk of neural tube defects: awareness and folate intake among pregnant women in 2006].

    Science.gov (United States)

    Kondo, Atsuo; Shimosuga, Yoichi; Oguchi, Hidenori; Shibata, Kanemitsu; Kurauchi, Osamu; Ichiko, Satoshi; Inoue, Hiromi; Tada, Katsuhiko; Yamada, Manshou; Kaseki, Nariaki; Narita, Osamu; Kusanishi, Hiroshi; Yamada, Yoshitaka; Yamamoto, Shin-Ichi; Ooura, Kuniaki; Takemura, Masahiko; Watanabe, Takanori; Ishihara, Osamu; Takeda, Akihiro; Watanabe, Junichiro; Wakita, Katsuji; Itoh, Kunihiko; Katoh, Sentoyo; Koyama, Masayasu; Oota, Shunji; Ninomiya, Keiu; Matsuzawa, Katsuji; Hujishima, Yoshiko; Ishida, Shoutarou; Okai, Ikuyo; Hayakawa, Chisa; Gotoh, Tohru

    2008-08-01

    Folic acid plays an important role in proliferating cells and tissues of the fetus. A randomized control trial demonstrated in 1991 that 4 mg of folic acid supplements successfully prevented 72% of recurrence of neural tube defects (NTDs) in women who had had afflicted pregnancy. In 2000, the Japanese Government recommended women of childbearing age to take 400 microgram of folate supplements per day from 4 weeks prior to and 12 weeks after conception. A questionnaire study was performed in pregnant women by post on their awareness of the role folic acid plays, their life style, and folate intake by dietary consumption. Thirty-five percent of 1,251 pregnant women were aware of the important role of folic acid in the critical stage of fetal development and 31% actually took the supplement. Information on folic acid was obtained through mass media in 47% of the women, through the internet in 17%, through healthcare providers in 13% and so forth. The food record analysis revealed that the dietary intake of folic acid averaged 341 microg/day that was 60 microg less than what was recommended by the Government and that 33 of 86 women took the supplement. Overall, a half of pregnant women are required to take 400 microg folate supplement per day. It is to be stressed that primary prevention of NTDs by periconceptional intake of folic acid is a major public health opportunity and that prevention is more important than cure in the management of NTDs.

  6. Nucleic acid-based approaches to investigate microbial-related cheese quality defects.

    Science.gov (United States)

    O'Sullivan, Daniel J; Giblin, Linda; McSweeney, Paul L H; Sheehan, Jeremiah J; Cotter, Paul D

    2013-01-01

    The microbial profile of cheese is a primary determinant of cheese quality. Microorganisms can contribute to aroma and taste defects, form biogenic amines, cause gas and secondary fermentation defects, and can contribute to cheese pinking and mineral deposition issues. These defects may be as a result of seasonality and the variability in the composition of the milk supplied, variations in cheese processing parameters, as well as the nature and number of the non-starter microorganisms which come from the milk or other environmental sources. Such defects can be responsible for production and product recall costs and thus represent a significant economic burden for the dairy industry worldwide. Traditional non-molecular approaches are often considered biased and have inherently slow turnaround times. Molecular techniques can provide early and rapid detection of defects that result from the presence of specific spoilage microbes and, ultimately, assist in enhancing cheese quality and reducing costs. Here we review the DNA-based methods that are available to detect/quantify spoilage bacteria, and relevant metabolic pathways in cheeses and, in the process, highlight how these strategies can be employed to improve cheese quality and reduce the associated economic burden on cheese processors.

  7. Nucleic acid-based approaches to investigate microbial-related cheese quality defects

    Directory of Open Access Journals (Sweden)

    Daniel eO Sullivan

    2013-01-01

    Full Text Available AbstractThe microbial profile of cheese is a primary determinant of cheese quality. Microorganisms can contribute to aroma and taste defects, form biogenic amines, cause gas and secondary fermentation defects, and can contribute to cheese pinking and mineral deposition issues. These defects may be as a result of seasonality and the variability in the composition of the milk supplied, variations in cheese processing parameters, as well as the nature and number of the non-starter microorganisms which come from the milk or other environmental sources. Such defects can be responsible for production and product recall costs and thus represent a significant economic burden for the dairy industry worldwide. Traditional non-molecular approaches are often considered biased and have inherently slow turnaround times. Molecular techniques can provide early and rapid detection of defects that result from the presence of specific spoilage microbes and, ultimately, assist in enhancing cheese quality and reducing costs. Here we review the DNA-based methods that are available to detect/quantify spoilage bacteria, and relevant metabolic pathways, in cheeses and, in the process, highlight how these strategies can be employed to improve cheese quality and reduce the associated economic burden on cheese processors.

  8. Triiodothyronine activates lactate oxidation without impairing fatty acid oxidation and improves weaning from extracorporeal membrane oxygenation

    Energy Technology Data Exchange (ETDEWEB)

    Kajimoto, Masaki; Ledee, Dolena R.; Xu, Chun; Kajimoto, Hidemi; Isern, Nancy G.; Portman, Michael A.

    2014-01-01

    Background: Extracorporeal membrane oxygenation (ECMO) provides a rescue for children with severe cardiac failure. We previously showed that triiodothyronine (T3) improves cardiac function by modulating pyruvate oxidation during weaning. This study was focused on fatty acid (FA) metabolism modulated by T3 for weaning from ECMO after cardiac injury. Methods: Nineteen immature piglets (9.1-15.3 kg) were separated into 3 groups with ECMO (6.5 hours) and wean: normal circulation (Group-C);transient coronary occlusion (10 minutes) followed by ECMO (Group-IR); and IR with T3 supplementation (Group-IR-T3). 13-Carbon labeled lactate, medium-chain and long-chain FAs were infused as oxidative substrates. Substrate fractional contribution to the citric acid cycle (FC) was analyzed by 13-Carbon nuclear magnetic resonance. Results: ECMO depressed circulating T3 levels to 40% baseline at 4 hours and were restored in Group-IR-T3. Group-IR decreased cardiac power, which was not fully restorable and 2 pigs were lost because of weaning failure. Group-IR also depressed FC-lactate, while the excellent contractile function and energy efficiency in Group-IR-T3 occurred along with a marked FC-lactate increase and [ATP]/[ADP] without either decreasing FC-FAs or elevating myocardial oxygen consumption over Group-C or -IR. Conclusions: T3 releases inhibition of lactate oxidation following ischemia-reperfusion injury without impairing FA oxidation. These findings indicate that T3 depression during ECMO is maladaptive, and that restoring levels improves metabolic flux and enhances contractile function during weaning.

  9. Effects of a tetracycline blended polylactic and polyglycolic acid membrane on the healing of one-wall intrabony defects in beagle dogs

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Il-Young [Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-752l (Korea, Republic of); Jung, Ui-Won [Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-752l (Korea, Republic of); Kim, Chang-Sung [Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-752l (Korea, Republic of); Lee, Yong-Keun [Department and Research Institute of Dental Biomaterials and Bioengineering, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-750 (Korea, Republic of); Cho, Kyoo-Sung [Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-752l (Korea, Republic of); Chai, Jung-Kiu [Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-752l (Korea, Republic of); Kim, Chong-Kwan [Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-752l (Korea, Republic of); Choi, Seong-Ho [Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-752l (Korea, Republic of)

    2007-09-15

    The purpose of this study was to evaluate the regenerative effects of a tetracycline blended polylactic and polyglycolic acid (TC-PLGA) and non-blended polylactic and polyglycolic acid (PLGA) barrier membrane on one-wall intrabony defects in beagle dogs. It can be concluded that when used for guided tissue regeneration TC-PLGA membranes show a beneficial effect on one-wall intrabony defects in beagle dogs.

  10. Rotational spectroscopy of the atmospheric photo-oxidation product o-toluic acid and its monohydrate.

    Science.gov (United States)

    Schnitzler, Elijah G; Zenchyzen, Brandi L M; Jäger, Wolfgang

    2016-01-07

    o-Toluic acid, a photo-oxidation product in the atmosphere, and its monohydrate were characterized in the gas phase by pure rotational spectroscopy. High-resolution spectra were measured in the range of 5-14 Hz using a cavity-based molecular beam Fourier-transform microwave spectrometer. Possible conformers were identified computationally, at the MP2/6-311++G(2df,2pd) level of theory. For both species, one conformer was identified experimentally, and no methyl internal rotation splittings were observed, indicative of relatively high barriers to rotation. In the monomer, rocking of the carboxylic acid group is a large amplitude motion, characterized by a symmetrical double-well potential. This and other low-lying out-of-plane vibrations contribute to a significant (methyl top-corrected) inertial defect (-1.09 amu Å(2)). In the monohydrate, wagging of the free hydrogen atom of water is a second large amplitude motion, so the average structure is planar. As a result, no c-type transitions were observed. Water tunneling splittings were not observed, because the water rotation coordinate is characterized by an asymmetrical double-well potential. Since the minima are not degenerate, tunneling is precluded. Furthermore, a concerted tunneling path involving simultaneous rotation of the water moiety and rocking of the carboxylic acid group is precluded, because the hilltop along this coordinate is a virtual, rather than a real, saddle-point. Inter- and intramolecular non-covalent bonding is discussed in terms of the quantum theory of atoms in molecules. The percentage of o-toluic acid hydrated in the atmosphere is estimated to be about 0.1% using statistical thermodynamics.

  11. Oxygen Point Defect Chemistry in Ruddlesden-Popper Oxides (La1-xSrx)2MO4±δ (M = Co, Ni, Cu).

    Science.gov (United States)

    Xie, Wei; Lee, Yueh-Lin; Shao-Horn, Yang; Morgan, Dane

    2016-05-19

    Stability of oxygen point defects in Ruddlesden-Popper oxides (La1-xSrx)2MO4±δ (M = Co, Ni, Cu) is studied with density functional theory calculations to determine their stable sites, charge states, and energetics as functions of Sr content (x), transition metal (M), and defect concentration (δ). We demonstrate that the dominant O point defects can change between oxide interstitials, peroxide interstitials, and vacancies. In general, increasing x and atomic number of M stabilizes peroxide over oxide interstitials as well as vacancies over both peroxide and oxide interstitials; increasing δ destabilizes both oxide interstitials and vacancies but barely affects peroxide interstitials. We also demonstrate that the O 2p-band center is a powerful descriptor for these materials and correlates linearly with the formation energy of all defects. The trends of formation energy versus x, M, and δ and the correlation with O 2p-band center are explained in terms of oxidation chemistry and electronic structure.

  12. Nondestructive covalent functionalization of carbon nanotubes by selective oxidation of the original defects with K{sub 2}FeO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhao-yang; Xu, Xue-cheng, E-mail: xcxu@phy.ecnu.edu.cn

    2015-08-15

    Graphical abstract: - Highlights: • Nondestructive covalent CNT functionalization is realized by defect oxidation. • A green oxidant K{sub 2}Fe{sup VI}O{sub 4} is used for CNT oxidation for the first time. • Effective CNT oxidation can be achieved at 60 °C in 3 h. • Oxidized CNTs are obtained in yields of above 100 wt%. • FeO{sub 3}, an unusual Fe (VI) specie, is produced when K{sub 2}FeO{sub 4} is dissolved in H{sub 2}SO{sub 4}. - Abstract: Chemical oxidation is still the major approach to the covalent functionalization of carbon nanotubes (CNTs). Theoretically, the defects on CNTs are more reactive than skeletal hexagons and should be preferentially oxidized, but conventional oxidation methods, e.g., HNO{sub 3}/H{sub 2}SO{sub 4} treatment, have poor reaction selectivity and inevitably consume the C=C bonds in the hexagonal lattices, leading to structural damage, π-electrons loss and weight decrease. In this work, we realized the nondestructive covalent functionalization of CNTs by selective oxidation of the defects. In our method, potassium ferrate K{sub 2}Fe{sup VI}O{sub 4} was employed as an oxidant for CNTs in H{sub 2}SO{sub 4} medium. The CNT samples, before and after K{sub 2}FeO{sub 4}/H{sub 2}SO{sub 4} treatment, were characterized with colloid dispersibility, IR, Raman spectroscopy, FESEM and XPS. The results indicated that (i) CNTs could be effectively oxidized by Fe (VI) under mild condition (60 °C, 3 h), and hydrophilic CNTs with abundant surface −COOH groups were produced; and (ii) Fe (VI) oxidation of CNTs followed a defect-specific oxidation process, that is, only the sp{sup 3}-hybridized carbon atoms on CNT surface were oxidized while the C=C bonds remained unaffected. This selective/nondestructive oxidation afforded oxidized CNTs in yields of above 100 wt%. This paper shows that K{sub 2}FeO{sub 4}/H{sub 2}SO{sub 4} is an effective, nondestructive and green oxidation system for oxidative functionalization of CNTs and probably other

  13. Graphene Oxide-Gallic Acid Nanodelivery System for Cancer Therapy

    Science.gov (United States)

    Dorniani, Dena; Saifullah, Bullo; Barahuie, Farahnaz; Arulselvan, Palanisamy; Hussein, Mohd Zobir Bin; Fakurazi, Sharida; Twyman, Lance J.

    2016-11-01

    Despite the technological advancement in the biomedical science, cancer remains a life-threatening disease. In this study, we designed an anticancer nanodelivery system using graphene oxide (GO) as nanocarrier for an active anticancer agent gallic acid (GA). The successful formation nanocomposite (GOGA) was characterized using XRD, FTIR, HRTEM, Raman, and UV/Vis spectroscopy. The release study shows that the release of GA from the designed anticancer nanocomposite (GOGA) occurs in a sustained manner in phosphate-buffered saline (PBS) solution at pH 7.4. In in vitro biological studies, normal fibroblast (3T3) and liver cancer cells (HepG2) were treated with different concentrations of GO, GOGA, and GA for 72 h. The GOGA nanocomposite showed the inhibitory effect to cancer cell growth without affecting normal cell growth. The results of this research are highly encouraging to go further for in vivo studies.

  14. Kinetic study of formic acid oxidation on carbon supported Pd electrocatalyst

    Science.gov (United States)

    Wang, Yujiao; Wu, Bing; Gao, Ying; Tang, Yawen; Lu, Tianhong; Xing, Wei; Liu, Changpeng

    The oxidation of formic acid at the Pd/C catalyst electrode is a completely irreversible kinetic process with the reaction order of 1.0. The oxidation rate of formic acid is increased with increasing the concentration of formic acid and is decreased with increasing H + concentration. The apparent negative reaction order with respect to H + is about -0.18 or -0.04 in H 2SO 4 or HClO 4 solution respectively, because bisulfate anions would inhibit formic acid oxidation at some extent. The kinetic parameters, charge transfer coefficient and the diffusion coefficient of formic acid were obtained under the quasi steady-state conditions.

  15. Supercritical water oxidation of acrylic acid production wastewater.

    Science.gov (United States)

    Gong, Y M; Wang, S Z; Tang, X Y; Xu, D H; Ma, H H

    2014-01-01

    Supercritical water oxidation (SCWO) of wastewater from an acrylic acid manufacturing plant has been studied on a continuous flow experimental system, whose reactor was made of Hastelloy C-276. Experimental conditions included a reaction temperature (T) ranging from 673 to 773K, a residence time (t) ranging from 72.7 to 339s, a constant pressure (P) of 25 MPa and a fixed oxidation coefficient (alpha) of 2.0. Experimental results indicated that reaction temperature and residence time had significant influences on the oxidation reaction, and increasing the two operation parameters could improve both degradation of chemical oxygen demand (COD) and ammonia nitrogen (NH3-N). The COD removal efficiency could reach up to 98.73% at 25 MPa, 773 K and 180.1 s, whereas the destruction efficiency of NH3-N was only 43.71%. We further carried out a kinetic analysis considering the induction period through free radical chain mechanism. It confirms that the power-law rate equation for COD removal was 345 exp(-52200/RT)[COD]1.98[O2]0.17 and for NH3-N removal was 500 exp(-64492.19/RT)[NH3-N]1.87 [O2]0.03. Moreover, the induction time formulations for COD and NH3-N were suspected to be exp(38250/RT)/173 and exp(55690/RT)/15231, respectively. Correspondingly, induction time changed from 2.22 to 5.38 s for COD and 0.38 to 1.38 s for NH3-N. Owing to the catalysis of reactor inner wall surface, more than 97% COD removal was achieved in all samples.

  16. Properties of nanocellulose isolated from corncob residue using sulfuric acid, formic acid, oxidative and mechanical methods.

    Science.gov (United States)

    Liu, Chao; Li, Bin; Du, Haishun; Lv, Dong; Zhang, Yuedong; Yu, Guang; Mu, Xindong; Peng, Hui

    2016-10-20

    In this work, nanocellulose was extracted from bleached corncob residue (CCR), an underutilized lignocellulose waste from furfural industry, using four different methods (i.e. sulfuric acid hydrolysis, formic acid (FA) hydrolysis, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation, and pulp refining, respectively). The self-assembled structure, morphology, dimension, crystallinity, chemical structure and thermal stability of prepared nanocellulose were investigated. FA hydrolysis produced longer cellulose nanocrystals (CNCs) than the one obtained by sulfuric acid hydrolysis, and resulted in high crystallinity and thermal stability due to its preferential degradation of amorphous cellulose and lignin. The cellulose nanofibrils (CNFs) with fine and individualized structure could be isolated by TEMPO-mediated oxidation. In comparison with other nanocellulose products, the intensive pulp refining led to the CNFs with the longest length and the thickest diameter. This comparative study can help to provide an insight into the utilization of CCR as a potential source for nanocellulose production. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Palladium-catalyzed air-based oxidative coupling of arylboronic acids with H-phosphine oxides leading to aryl phosphine oxides.

    Science.gov (United States)

    Fu, Tingting; Qiao, Hongwei; Peng, Zhimin; Hu, Gaobo; Wu, Xueji; Gao, Yuxing; Zhao, Yufen

    2014-05-14

    We present a novel and highly efficient methodology that allows for the construction of C-P bonds via the palladium-catalyzed air-based oxidative coupling of various commercially available arylboronic acids with easily oxidized H-phosphine oxides leading to valuable aryl phosphine oxides, particularly triarylphosphine oxides, with the use of air as the green oxidant, broad substrate applicability and good to excellent yields. The described catalytic system should be an efficient complement to the Chan-Lam type reaction and be useful in synthetic programs.

  18. Defective iron-oxide nanoparticles synthesised by high temperature plasma processing: a magnetic characterisation versus temperature

    Science.gov (United States)

    Balasubramanian, C.; Joseph, B.; Orpe, PB; Saini, NL; Mukherjee, S.; Dziedzic-Kocurek, K.; Stanek, J.; Di Gioacchino, D.; Marcelli, A.

    2016-11-01

    Magnetic properties and phase compositions of iron-oxide nanoparticles synthesised by a high temperature arc plasma route have been investigated by Mössbauer spectroscopy and high harmonic magnetic AC susceptibility measurements, and correlated with morphological and structural properties for different synthesis conditions. The Mössbauer spectra precisely determined the presence of different iron-oxide fractions in the investigated nanoparticles, while the high harmonic magnetic susceptibility measurements revealed the occurrence of metastable magnetic phases evolving in temperature and time. This study illustrates magnetic properties and dynamics of the magnetic configurations of iron-oxide nanoparticles grown by high temperature plasma, a process less explored so far but extremely useful for synthesising large numbers of nanoparticles for industrial applications.

  19. Fatty Acid Incubation of Myotubues from Humans with Type 2 Diabetes Leads to Enhanced Release of Beta Oxidation Products Due to Impaired Fatty Acid Oxidation

    DEFF Research Database (Denmark)

    Wensaas, Andreas J; Rustan, Arild C; Just, Marlene

    2008-01-01

    Objective: Increased availability of fatty acids is important for accumulation of intracellular lipids and development of insulin resistance in human myotubes. It is unknown whether different types of fatty acids like eicosapentaenoic acid (EPA) or tetradecylthioacetic acid (TTA) influence...... these processes. Research Design and Methods: We examined fatty acid and glucose metabolism, and gene expression in cultured human skeletal muscle cells from control and T2D individuals after four days preincubation with EPA or TTA. Results: T2D myotubes exhibited reduced formation of CO(2) from palmitic acid (PA....... EPA markedly enhanced TAG accumulation in myotubes, more pronounced in T2D cells. TAG accumulation and fatty acid oxidation were inversely correlated only after EPA preincubation, and total level of acyl-CoA was reduced. Glucose oxidation (CO(2) formation) was enhanced and lactate production decreased...

  20. Graphene oxide induces plasma membrane damage, reactive oxygen species accumulation and fatty acid profiles change in Pichia pastoris.

    Science.gov (United States)

    Zhang, Meng; Yu, Qilin; Liang, Chen; Liu, Zhe; Zhang, Biao; Li, Mingchun

    2016-10-01

    During the past couple of years, graphene nanomaterials were extremely popular among the scientists due to the promising properties in many aspects. Before the materials being well applied, we should first focus on their biosafety and toxicity. In this study, we investigated the toxicity of synthesized graphene oxide (GO) against the model industrial organism Pichia pastoris. We found that the synthesized GO showed dose-dependent toxicity to P. pastoris, through cell membrane damage and intracellular reactive oxygen species (ROS) accumulation. In response to these cell stresses, cells had normal unsaturated fatty acid (UFA) levels but increased contents of polyunsaturated fatty acid (PUFA) with up-regulation of UFA synthesis-related genes on the transcriptional level, which made it overcome the stress under GO attack. Two UFA defective strains (spt23Δ and fad12Δ) were used to demonstrate the results above. Hence, this study suggested a close connection between PUFAs and cell survival against GO.

  1. Oxidation of indole-3-acetic acid to oxindole-3-acetic acid by an enzyme preparation from Zea mays

    Science.gov (United States)

    Reinecke, D. M.; Bandurski, R. S.

    1988-01-01

    Indole-3-acetic acid is oxidized to oxindole-3-acetic acid by Zea mays tissue extracts. Shoot, root, and endosperm tissues have enzyme activities of 1 to 10 picomoles per hour per milligram protein. The enzyme is heat labile, is soluble, and requires oxygen for activity. Cofactors of mixed function oxygenase, peroxidase, and intermolecular dioxygenase are not stimulatory to enzymic activity. A heat-stable, detergent-extractable component from corn enhances enzyme activity 6- to 10-fold. This is the first demonstration of the in vitro enzymic oxidation of indole-3-acetic acid to oxindole-3-acetic acid in higher plants.

  2. Oxidation of indole-3-acetic acid to oxindole-3-acetic acid by an enzyme preparation from Zea mays

    Science.gov (United States)

    Reinecke, D. M.; Bandurski, R. S.

    1988-01-01

    Indole-3-acetic acid is oxidized to oxindole-3-acetic acid by Zea mays tissue extracts. Shoot, root, and endosperm tissues have enzyme activities of 1 to 10 picomoles per hour per milligram protein. The enzyme is heat labile, is soluble, and requires oxygen for activity. Cofactors of mixed function oxygenase, peroxidase, and intermolecular dioxygenase are not stimulatory to enzymic activity. A heat-stable, detergent-extractable component from corn enhances enzyme activity 6- to 10-fold. This is the first demonstration of the in vitro enzymic oxidation of indole-3-acetic acid to oxindole-3-acetic acid in higher plants.

  3. Comparison of defects in crystalline oxide semiconductor materials by electron spin resonance

    Energy Technology Data Exchange (ETDEWEB)

    Matsuda, Tokiyoshi, E-mail: toki@rins.ryukoku.ac.jp; Kimura, Mutsumi [Department of Electronics and Informatics, Faculty of Science and Technology, Ryukoku University, 1-438, 1-5 Yokotani, Seta Oe-Cho, Otsu, Shiga 520-2194, Japan and Joint Research Center for Science and Technology, Ryukoku University, 1-5 Yokotani, Seta Oe-Cho, Otsu, Shiga 520-2194 (Japan)

    2015-03-15

    Defects in crystalline InGaZnO{sub 4} (IGZO) induced by plasma were investigated using electron spin resonance (ESR). Thermal stabilities and g factors of two ESR signals (A and B observed at g = 1.939 and 2.003, respectively) in IGZO were different from those of the ESR signals observed in component materials such as Ga{sub 2}O{sub 3} (signal observed at g = 1.969), In{sub 2}O{sub 3} (no signal), and ZnO (signal observed at g = 1.957). Signal A in IGZO increased upon annealing at 300 °C for 1 h, but decreased when annealing was continued for more than 2 h. On the other hand, signal B decreased upon annealing at 300 °C for 1 h. The ESR signal in ZnO decayed in accordance with a second-order decay model with a rate constant of 2.1 × 10{sup −4} s{sup −1}; however, this phenomenon was not observed in other materials. This difference might have been due to randomly formed IGZO lattices such as asymmetrical (Ga, Zn)O and In-O layers. Defects in signals A and B in IGZO were formed in trap states (at the deep level) and tail states, respectively.

  4. Identification of defective illegitimate recombinational repair of oxidatively-induced DNA double-strand breaks in ataxia-telangiectasia cells

    Science.gov (United States)

    Dar, M. E.; Winters, T. A.; Jorgensen, T. J.

    1997-01-01

    Ataxia-telangiectasia (A-T) is an autosomal-recessive lethal human disease. Homozygotes suffer from a number of neurological disorders, as well as very high cancer incidence. Heterozygotes may also have a higher than normal risk of cancer, particularly for the breast. The gene responsible for the disease (ATM) has been cloned, but its role in mechanisms of the disease remain unknown. Cellular A-T phenotypes, such as radiosensitivity and genomic instability, suggest that a deficiency in the repair of DNA double-strand breaks (DSBs) may be the primary defect; however, overall levels of DSB rejoining appear normal. We used the shuttle vector, pZ189, containing an oxidatively-induced DSB, to compare the integrity of DSB rejoining in one normal and two A-T fibroblast cells lines. Mutation frequencies were two-fold higher in A-T cells, and the mutational spectrum was different. The majority of the mutations found in all three cell lines were deletions (44-63%). The DNA sequence analysis indicated that 17 of the 17 plasmids with deletion mutations in normal cells occurred between short direct-repeat sequences (removing one of the repeats plus the intervening sequences), implicating illegitimate recombination in DSB rejoining. The combined data from both A-T cell lines showed that 21 of 24 deletions did not involve direct-repeats sequences, implicating a defect in the illegitimate recombination pathway. These findings suggest that the A-T gene product may either directly participate in illegitimate recombination or modulate the pathway. Regardless, this defect is likely to be important to a mechanistic understanding of this lethal disease.

  5. An RMND1 Mutation causes encephalopathy associated with multiple oxidative phosphorylation complex deficiencies and a mitochondrial translation defect.

    Science.gov (United States)

    Janer, Alexandre; Antonicka, Hana; Lalonde, Emilie; Nishimura, Tamiko; Sasarman, Florin; Brown, Garry K; Brown, Ruth M; Majewski, Jacek; Shoubridge, Eric A

    2012-10-05

    Mutations in the genes composing the mitochondrial translation apparatus are an important cause of a heterogeneous group of oxidative phosphorylation (OXPHOS) disorders. We studied the index case in a consanguineous family in which two children presented with severe encephalopathy, lactic acidosis, and intractable seizures leading to an early fatal outcome. Blue native polyacrylamide gel electrophoretic (BN-PAGE) analysis showed assembly defects in all of the OXPHOS complexes with mtDNA-encoded structural subunits, and these defects were associated with a severe deficiency in mitochondrial translation. Immunoblot analysis showed reductions in the steady-state levels of several structural subunits of the mitochondrial ribosome. Whole-exome sequencing identified a homozygous missense mutation (c.1250G>A) in an uncharacterized gene, RMND1 (required for meiotic nuclear division 1). RMND1 localizes to mitochondria and behaves as an integral membrane protein. Retroviral expression of the wild-type RMND1 cDNA rescued the biochemical phenotype in subject cells, and siRNA-mediated knockdown of the protein recapitulated the defect. BN-PAGE, gel filtration, and mass spectrometry analyses showed that RMND1 forms a high-molecular-weight and most likely homopolymeric complex (∼240 kDa) that does not assemble in subject fibroblasts but that is rescued by expression of RMND1 cDNA. The p.Arg417Gln substitution, predicted to be in a coiled-coil domain, which is juxtaposed to a transmembrane domain at the extreme C terminus of the protein, does not alter the steady-state level of RMND1 but might prevent protein-protein interactions in this complex. Our results demonstrate that the RMND1 complex is necessary for mitochondrial translation, possibly by coordinating the assembly or maintenance of the mitochondrial ribosome. Copyright © 2012 The American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.

  6. Integrating nitric oxide into salicylic acid and jasmonic acid/ethylene plant defense pathways

    DEFF Research Database (Denmark)

    Mur, Luis A J; Prats, Elena; Pierre, Sandra

    2013-01-01

    Plant defence against pests and pathogens is known to be conferred by either salicylic acid (SA) or jasmonic acid (JA)/ethylene (ET) pathways, depending on infection or herbivore-grazing strategy. It is well attested that SA and JA/ET pathways are mutually antagonistic allowing defence responses...... to be tailored to particular biotic stresses. Nitric oxide (NO) has emerged as a major signal influencing resistance mediated by both signalling pathways but no attempt has been made to integrate NO into established SA/JA/ET interactions. NO has been shown to act as an inducer or suppressor of signalling along...... the cytoplasm to reduce TGA activation. In JA biosynthesis, NO will initiate the expression of JA biosynthetic enzymes, presumably to over-come any antagonistic effects of SA on JA-mediated transcription. NO will also initiate the expression of ET biosynthetic genes but a suppressive role is also observed...

  7. Ab initio Defect Energetics in LaBO3 Perovskite Solid Oxide Fuel Cell Materials

    DEFF Research Database (Denmark)

    Lee, Yueh-Lin; Morgan, Dane; Kleis, Jesper;

    2009-01-01

    Perovskite materials of the form ABO3 are a promising family of compounds for use in solid oxide fuel cell (SOFC) cathodes. Study of the physics of these compounds under SOFC conditions with ab initio methods is particularly challenging due to high temperatures, exchange of oxygen with O2 gas...

  8. Mitochondrial defects and oxidative stress in Alzheimer disease and Parkinson disease.

    Science.gov (United States)

    Yan, Michael H; Wang, Xinglong; Zhu, Xiongwei

    2013-09-01

    Alzheimer disease (AD) and Parkinson disease (PD) are the two most common age-related neurodegenerative diseases characterized by prominent neurodegeneration in selective neural systems. Although a small fraction of AD and PD cases exhibit evidence of heritability, among which many genes have been identified, the majority are sporadic without known causes. Molecular mechanisms underlying neurodegeneration and pathogenesis of these diseases remain elusive. Convincing evidence demonstrates oxidative stress as a prominent feature in AD and PD and links oxidative stress to the development of neuronal death and neural dysfunction, which suggests a key pathogenic role for oxidative stress in both AD and PD. Notably, mitochondrial dysfunction is also a prominent feature in these diseases, which is likely to be of critical importance in the genesis and amplification of reactive oxygen species and the pathophysiology of these diseases. In this review, we focus on changes in mitochondrial DNA and mitochondrial dynamics, two aspects critical to the maintenance of mitochondrial homeostasis and function, in relationship with oxidative stress in the pathogenesis of AD and PD.

  9. Aerobic bacterial pyrite oxidation and acid rock drainage during the Great Oxidation Event.

    Science.gov (United States)

    Konhauser, Kurt O; Lalonde, Stefan V; Planavsky, Noah J; Pecoits, Ernesto; Lyons, Timothy W; Mojzsis, Stephen J; Rouxel, Olivier J; Barley, Mark E; Rosìere, Carlos; Fralick, Phillip W; Kump, Lee R; Bekker, Andrey

    2011-10-19

    The enrichment of redox-sensitive trace metals in ancient marine sedimentary rocks has been used to determine the timing of the oxidation of the Earth's land surface. Chromium (Cr) is among the emerging proxies for tracking the effects of atmospheric oxygenation on continental weathering; this is because its supply to the oceans is dominated by terrestrial processes that can be recorded in the Cr isotope composition of Precambrian iron formations. However, the factors controlling past and present seawater Cr isotope composition are poorly understood. Here we provide an independent and complementary record of marine Cr supply, in the form of Cr concentrations and authigenic enrichment in iron-rich sedimentary rocks. Our data suggest that Cr was largely immobile on land until around 2.48 Gyr ago, but within the 160 Myr that followed--and synchronous with independent evidence for oxygenation associated with the Great Oxidation Event (see, for example, refs 4-6)--marked excursions in Cr content and Cr/Ti ratios indicate that Cr was solubilized at a scale unrivalled in history. As Cr isotope fractionations at that time were muted, Cr must have been mobilized predominantly in reduced, Cr(III), form. We demonstrate that only the oxidation of an abundant and previously stable crustal pyrite reservoir by aerobic-respiring, chemolithoautotrophic bacteria could have generated the degree of acidity required to solubilize Cr(III) from ultramafic source rocks and residual soils. This profound shift in weathering regimes beginning at 2.48 Gyr ago constitutes the earliest known geochemical evidence for acidophilic aerobes and the resulting acid rock drainage, and accounts for independent evidence of an increased supply of dissolved sulphate and sulphide-hosted trace elements to the oceans around that time. Our model adds to amassing evidence that the Archaean-Palaeoproterozoic boundary was marked by a substantial shift in terrestrial geochemistry and biology.

  10. Influence of defects and processing parameters on the properties of indium tin oxide films on polyethylene napthalate substrate

    Science.gov (United States)

    Han, H.; Zoo, Yeongseok; Bhagat, S. K.; Lewis, J. S.; Alford, T. L.

    2007-09-01

    Indium tin oxide (ITO) thin films were deposited on polyethylene napthalate (PEN) by rf sputtering using different rf powers (60 and 120W) and at different substrate temperatures (room temperature and 100°C). Selected PEN substrates were pretreated using an Ar plasma before ITO sputter deposition. Rutherford backscattering spectrometry was used to determine the oxygen content in the films. Hall effect measurements were used to evaluate the electrical properties. In this paper the influence of defect structure, sputtering conditions, and the effect of annealing on the electrical and optical properties of ITO on PEN have been investigated. Electrical properties such as carrier concentration, mobility, and resistivity of the ITO films varied with rf power and substrate temperature. The electrical and optical properties of the films changed after annealing in air. This study also describes how the as-deposited amorphous ITO changes from amorphous to crystalline as a result of heat treatment, and investigates the effects of Sn defect clustering on electrical and optical properties of the ITO films.

  11. 40 CFR 721.3680 - Ethylene oxide adduct of fatty acid ester with pentaerythritol.

    Science.gov (United States)

    2010-07-01

    ... ester with pentaerythritol. 721.3680 Section 721.3680 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.3680 Ethylene oxide adduct of fatty acid ester with... identified generically as ethylene oxide adduct of fatty acid ester with pentaerythritol (PMN P-91-442)...

  12. Study of Oxidation of Glutathione Treated with Hypochlorous Acid by Capillary Electrophoresis

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Capillary electrophoresis (CE) method was developed for the separation and quantification of reduced glutathione (GSH), oxidized glutathione (GSSG) and glutathione sulphonic acid (GSO3H). Baseline separation was obtained within five minutes. The effects of reaction time and molar ratio of hypochlorous acid (HOCI) to GSH on the oxidation of GSH were investigated.

  13. Hepatic fatty acid oxidation : activity, localization and function of some enzymes involved

    NARCIS (Netherlands)

    A. van Tol (Arie)

    1971-01-01

    textabstractFatty acid oxidation is an important pathway for energy production in mammals and birds. In animal tissues the enzymes of fatty acid oxidation are located in the mitochondrion. Recent reports suggest that this is not the case in Castor bean endosperm. In this tissue the enzymes of

  14. Modeling of Semiconductors and Correlated Oxides with Point Defects by First Principles Methods

    KAUST Repository

    Wang, Hao

    2014-06-15

    Point defects in silicon, vanadium dioxide, and doped ceria are investigated by density functional theory. Defects involving vacancies and interstitial oxygen and carbon in silicon are after formed in outer space and significantly affect device performances. The screened hybrid functional by Heyd-Scuseria-Ernzerhof is used to calculate formation energies, binding energies, and electronic structures of the defective systems because standard density functional theory underestimates the bang gap of silicon. The results indicate for the A-center a −2 charge state. Tin is proposed to be an effective dopant to suppress the formation of A-centers. For the total energy difference between the A- and B-type carbon related G-centers we find close agreement with the experiment. The results indicate that the C-type G-center is more stable than both the A- and B-types. The electronic structures of the monoclinic and rutile phases of vanadium dioxide are also studied using the Heyd-Scuseria-Ernzerhof functional. The ground states of the pure phases obtained by calculations including spin polarization disagree with the experimental observations that the monoclinic phase should not be magnetic, the rutile phase should be metallic, and the monoclinic phase should have a lower total energy than the rutile phase. By tuning the Hartree-Fock fraction α to 10% the agreement with experiments is improved in terms of band gaps and relative energies of the phases. A calculation scheme is proposed to simulate the relationship between the transition temperature of the metal-insulator transition and the dopant concentration in tungsten doped vanadium dioxide. We achieve good agreement with the experimental situation. 18.75% and 25% yttrium, lanthanum, praseodymium, samarium, and gadolinium doped ceria supercells generated by the special quasirandom structure approach are employed to investigate the impact of doping on the O diffusion. The experimental behavior of the conductivity for the

  15. [Treatment of acute full-thickness chondral defects with high molecular weight hyaluronic acid; an experimental model].

    Science.gov (United States)

    Figueroa, D; Espinosa, M; Calvo, R; Scheu, M; Valderrama, J J; Gallegos, M; Conget, P

    2014-01-01

    To evaluate the effect of 2 different protocols of intra-articular hyaluronic acid (HA, hylan G-F20) to articular cartilage regeneration in acute full-thickness chondral defects. Full-thickness chondral defects of 3 x 6 mm were performed into the lateral femoral condyles of New Zealand rabbits, treated with a single or three doses of HA. The animals were sacrified at 12 weeks and the regenerated tissue was evaluated by direct observation and histology with the ICRS scale. Macroscopically, in both groups treated with HA the defects were filled with irregular tissue with areas similar to hyaline cartilage and others in which depressed areas with exposed subchondral bone were observed. Histological analysis showed in both groups treated with HA a hyaline-like cartilage compared to control group. However, the score of the International Cartilage Repair Society (ICRS) scale did not show differences between the groups treated with HA. The use of single dose or 3 doses of AH in acute chondral lesions has a limited and similar benefit in articular cartilage regeneration. Copyright © 2014 SECOT. Published by Elsevier Espana. All rights reserved.

  16. Stimulation of polyunsaturated fatty acid oxidation in myocytes by regulating its cellular uptake

    Energy Technology Data Exchange (ETDEWEB)

    Abdel-aleem, S.; Frangakis, C. (Glaxo Inc., Research Triangle Park, NC (USA)); Badr, M. (Univ. of Missouri-Kansas City, MO (USA))

    1991-01-01

    In order to investigate the regulation of polyunsaturated fatty acid oxidation in the heart, the effect of the phosphodiesterase inhibitor enoximone on the oxidation of (1-{sup 14}C) arachidonic acid, and (1-{sup 14}C) arachidonyl-CoA, were studied in adult rat myocytes, and isolated rat heart mitochondria. Enoximone stimulated arachidonate oxidation by 94%, at a concentration of 0.25 mM. The apparent Vmax value of archidonate oxidation in the presence of enoximone was approximately 75% higher than the value observed with the control in isolated myocytes. Also, enoximone stimulated arachidonate uptake by 27% at a concentration of 0.25 mM. On the other hand, enoximone had no effect on the oxidation of (1-{sup 14}C) arachidonyl-CoA in isolated rat heart mitochondria. These results suggest that the oxidation of polyunsaturated fatty acids in myocytes is regulated by the rate of uptake of these acids across sarcolemmal membranes.

  17. Point defects and transport in binary and ternary, non-stoichiometric oxides

    Energy Technology Data Exchange (ETDEWEB)

    Aggarwal, Sanjeev; Toepfer, Joerg; Tsai, Tse-Lun; Dieckmann, Ruediger [Department of Materials Science and Engineering, Bard Hall, Cornell University, Ithaca (United States)

    1997-09-29

    Discussed are: (1) experimental results for the variation of the oxygen content, the electrical conductivity and the iron tracer diffusion in fayalite, Fe{sub 2}SiO{sub 4}, (2) the relationship between point defects, the deviation from stoichiometry, {delta}, in Fe{sub 3-{delta}}O{sub 4} and the iron tracer diffusion, (3) the deviation from stoichiometry and the cation tracer diffusion in iron-based spinels of the type (Me{sub x}Fe{sub 1-x}){sub 3-{delta}}O{sub 4} and (4) the influence of near-boundary regions in polycrystalline Fe{sub 3-{delta}}O{sub 4} and Cu{sub 2-{delta}}O on the overall variation of the oxygen content as a function of the oxygen partial pressure

  18. Defects and their origin in thin films of (001) alkaline earth oxides

    Energy Technology Data Exchange (ETDEWEB)

    Walker, F.J. [Oak Ridge National Lab., TN (United States)]|[Tennessee Univ., Knoxville, TN (United States). Dept. of Materials Science and Engineering; McKee, R.A.; Pennycook, S.J.; Thundat, T.G. [Oak Ridge National Lab., TN (United States)

    1995-12-31

    MgO is used as an optical isolation layer for waveguides epitaxially grown on Si. Crystalline perfection of MgO is critical because it serves as a substrate for the single crytal, perovskite guiding layer. Imperfections in the MgO will result in imperfections in the guiding layer and lead to large optical losses for the planar waveguide structure. It is shown that the most common defect to form in thin MgO films are twin boundaries between {l_brace}111{r_brace}-type planes. Highest density of twins is observed when (001) MgO is grown directly on silicon/MgO interlayers containing Ba. Twinning is shown to accommodate the large size of Ba impurities incorporated in the MgO films through formation of internal grain boundaries and oper surface other than the growing (001) of MgO.

  19. Enzymology of the branched-chain amino acid oxidation disorders: the valine pathway.

    Science.gov (United States)

    Wanders, Ronald J A; Duran, Marinus; Loupatty, Ference J

    2012-01-01

    Valine is one of the three branched-chain amino acids which undergoes oxidation within mitochondria. In this paper, we describe the current state of knowledge with respect to the enzymology of the valine oxidation pathway and the different disorders affecting oxidation.

  20. Reduction reaction analysis of nanoparticle copper oxide for copper direct bonding using formic acid

    Science.gov (United States)

    Fujino, Masahisa; Akaike, Masatake; Matsuoka, Naoya; Suga, Tadatomo

    2017-04-01

    Copper direct bonding is required for electronics devices, especially power devices, and copper direct bonding using formic acid is expected to lower the bonding temperature. In this research, we analyzed the reduction reaction of copper oxide using formic acid with a Pt catalyst by electron spin resonance analysis and thermal gravimetry analysis. It was found that formic acid was decomposed and radicals were generated under 200 °C. The amount of radicals generated was increased by adding the Pt catalyst. Because of these radicals, both copper(I) oxide and copper(II) oxide start to be decomposed below 200 °C, and the reduction of copper oxide is accelerated by reactants such as H2 and CO from the decomposition of formic acid above 200 °C. The Pt catalyst also accelerates the reaction of copper oxide reduction. Herewith, it is considered that the copper surface can be controlled more precisely by using formic acid to induce direct bonding.

  1. Enhancing the crystalline degree of carbon nanotubes by acid treatment, air oxidization and heat treatment

    Institute of Scientific and Technical Information of China (English)

    Chensha Li; Baoyou Zhang; Xingjuan Chen; Xiaoqing Hu; Ji Liang

    2005-01-01

    Three approaches of treating carbon nanotubes (CNTs) including acid treatment, air oxidization and heat treatment at high temperature were studied to enhance the crystalline degree of carbon nanotubes. High temperature heat-treatment elevates the crystalline degree of carbon nanotubes. Acid treatment removes parts of amorphous carbonaceous matter through its oxidization effect.Air oxidization disperses carbon nanotubes and amorphous carbonaceous matter. The treatment of combining acid treatment with heat-treatment further elevates the crystalline degree of carbon nanotubes comparing with acid treatment or heat-treatment. The combination of the three treatments creates the thorough effects of enhancing the crystalline degree of carbon nanotubes.

  2. Manoyl oxide alpha-arabinopyranoside and grindelic acid diterpenoids from Grindelia integrifolia.

    Science.gov (United States)

    Ahmed, A A; Mahmoud, A A; Ahmed, U M; El-Bassuony, A A; Abd El-Razk, M H; Pare, P W; Karchesy, J

    2001-10-01

    Two new manoyl oxide-alpha-arabinopyranoside diterpenoids, 15-hydroxy-13-epi-manoyl oxide-14-O-alpha-L-arabinopyranoside (tarapacol-14-O-alpha-L-arabinopyranoside) (1) and 15-acetoxy-13-epi-manoyl oxide-14-O-alpha-L-arabinopyranoside (tarapacol-15-acetate-14-O-alpha-L-arabinopyranoside) (2), as well as a new grindelic acid derivative, 19-hydroxygrindelic acid (3), together with five known diterpenoids (tarapacol, tarapacanol A, grindelic acid, methyl grindeloate, 3beta-hydroxygrindelic acid, 4) were isolated from the aerial parts of Grindelia integrifolia. The structures of 1-3 were elucidated by spectral data analysis.

  3. High Performance Nano-Crystalline Oxide Fuel Cell Materials. Defects, Structures, Interfaces, Transport, and Electrochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Barnett, Scott [Northwestern Univ., Evanston, IL (United States); Poeppelmeier, Ken [Northwestern Univ., Evanston, IL (United States); Mason, Tom [Northwestern Univ., Evanston, IL (United States); Marks, Lawrence [Northwestern Univ., Evanston, IL (United States); Voorhees, Peter [Northwestern Univ., Evanston, IL (United States)

    2016-09-07

    This project addresses fundamental materials challenges in solid oxide electrochemical cells, devices that have a broad range of important energy applications. Although nano-scale mixed ionically and electronically conducting (MIEC) materials provide an important opportunity to improve performance and reduce device operating temperature, durability issues threaten to limit their utility and have remained largely unexplored. Our work has focused on both (1) understanding the fundamental processes related to oxygen transport and surface-vapor reactions in nano-scale MIEC materials, and (2) determining and understanding the key factors that control their long-term stability. Furthermore, materials stability has been explored under the “extreme” conditions encountered in many solid oxide cell applications, i.e, very high or very low effective oxygen pressures, and high current density.

  4. Humic acids as electron acceptors for anaerobic microbial oxidation of vinyl chloride and dichloroethene

    Science.gov (United States)

    Bradley, P.M.; Chapelle, F.H.; Lovley, D.R.

    1998-01-01

    Anaerobic oxidation of [1,2-14C]vinyl chloride and [1,2- 14C]dichloroethene to 14CO2 under humic acid-reducing conditions was demonstrated. The results indicate that waterborne contaminants can be oxidized by using humic acid compounds as electron acceptors and suggest that natural aquatic systems have a much larger capacity for contaminant oxidation than previously thought.

  5. Densification of Highly Defective Ceria by High Temperature Controlled Re-Oxidation

    DEFF Research Database (Denmark)

    Ni, De Wei; Glasscock, Julie; Pons, Aénor;

    2014-01-01

    Highly enhanced densification and grain growth of Ce0.9Gd0.1O1.95-δ (CGO, gadolinium-doped ceria, with 10 mol% Gd) is achieved in low oxygen activity atmospheres. However, the material can suffer mechanical failures during cooling when the re-oxidation process is not controlled due to the large v...... by the chemical history of the material. © 2014 The Electrochemical Society....

  6. Application of layered poly (L-lactic acid cell free scaffold in a rabbit rotator cuff defect model

    Directory of Open Access Journals (Sweden)

    Inui Atsuyuki

    2011-12-01

    Full Text Available Abstract Background This study evaluated the application of a layered cell free poly (L-lactic acid (PLLA scaffold to regenerate an infraspinatus tendon defect in a rabbit model. We hypothesized that PLLA scaffold without cultivated cells would lead to regeneration of tissue with mechanical properties similar to reattached infraspinatus without tendon defects. Methods Layered PLLA fabric with a smooth surface on one side and a pile-finished surface on the other side was used. Novel form of layered PLLA scaffold was created by superimposing 2 PLLA fabrics. Defects of the infraspinatus tendon were created in 32 rabbits and the PLLA scaffolds were transplanted, four rabbits were used as normal control. Contralateral infraspinatus tendons were reattached to humeral head without scaffold implantation. Histological and mechanical evaluations were performed at 4, 8, and 16 weeks after operation. Results At 4 weeks postoperatively, cell migration was observed in the interstice of the PLLA fibers. Regenerated tissue was directly connected to the bone composed mainly of type III collagen, at 16 weeks postoperatively. The ultimate failure load increased in a time-dependent manner and no statistical difference was seen between normal infraspinatus tendon and scaffold group at 8 and 16 weeks postoperatively. There were no differences between scaffold group and reattach group at each time of point. The stiffness did not improve significantly in both groups. Conclusions A novel form of layered PLLA scaffold has the potential to induce cell migration into the scaffold and to bridge the tendon defect with mechanical properties similar to reattached infraspinatus tendon model.

  7. Folic acid fortification and prevalences of neural tube defects, orofacial clefts, and gastroschisis in California, 1989 to 2010.

    Science.gov (United States)

    Yang, Wei; Carmichael, Suzan L; Shaw, Gary M

    2016-12-01

    We examined whether prevalences of neural tube defects (NTDs), orofacial clefts, and gastroschisis changed more rapidly after than before folic acid fortification in California. This population-based study used vital statistics and birth defects registry data. The study population included all live births and stillbirths delivered in central California counties from 1989 to 2010. Cases included deliveries with NTDs, orofacial clefts, and gastroschisis. Weighted least squares regression was used to estimate slopes during prefortification (before 1997) and postfortification (after 1998), respectively. The difference of the two slopes with the 95% confidence interval (CI) was calculated. For all NTDs combined, slopes indicated that NTD prevalence was decreasing by 8.7 (slope: -8.7; 95% CI, -13.5--3.9) cases per 100,000 deliveries per year before fortification and by 1.7 (slope: -1.7; 95% CI, -3.7-0.3) after fortification; thus the decline had slowed by 7.0 (95% CI, 2.7-11.3) cases per 100,000 deliveries per year. For orofacial clefts, slopes for cleft lip with/without palate as well as for cleft palate alone indicated that the postfortification slope was lower than the prefortification slope suggesting a more accelerated decrease in the postfortification time period. For gastroschisis, the slope after fortification was lower compared with prefortification, indicating a less accelerated prevalence increase in the postfortification time period. Stratification by race/ethnicity did not substantially alter results. We observed a slower decline in prevalence of NTDs, an emergence of a decline in orofacial clefts, and a slower increase in gastroschisis, during the postfortification period in central California, relative to the prefortification period. Birth Defects Research (Part A), 2016. © 2016 Wiley Periodicals, Inc. Birth Defects Research (Part A) 106:1032-1041, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  8. Birth Defects: Cerebral Palsy

    Science.gov (United States)

    ... defects, premature birth and infant mortality. Solving premature birth Featured articles Accomplishments and lessons learned since the ... and pregnancy Folic acid Medicine safety and pregnancy Birth defects prevention Learn how to help reduce your ...

  9. Point defects and irradiation in oxides: simulations at the atomic scale; Defauts ponctuels et irradiation dans les oxydes: simulation a l'echelle atomique

    Energy Technology Data Exchange (ETDEWEB)

    Crocombette, J.P

    2005-12-15

    The studies done by Jean-Paul Crocombette between 1996 and 2005 in the Service de Recherches de Metallurgie Physique of the Direction de l'Energie Nucleaire in Saclay are presented in this Habilitation thesis. These works were part of the material science researches on the ageing, especially under irradiation, of oxides of interest for the nuclear industry. In this context simulation studies at the atomic scale were performed on two elementary components of ageing under irradiation : point defects and displacement cascades ; using two complementary simulation techniques : ab initio electronic structure calculations and empirical potential molecular dynamics. The first part deals with point defects : self defects (vacancies or interstitials) or hetero-atomic dopants. One first recalls the energetics of such defects in oxides, the specific features of defects calculations and the expected accuracy of these calculations. Then one presents the results obtained on uranium dioxide, oxygen in silver and amorphous silica. The second part tackles the modelling of disintegration recoil nuclei in various?displacement cascades created by crystalline matrices for actinide waste disposal. Cascade calculations give access to the amorphization mechanisms under irradiation of these materials. One thus predicts that the amorphization in zircon takes place directly in the tracks whereas in lanthanum zirconate, the amorphization proceeds through the accumulation of point defects. Finally the prospects of these studies are discussed. (author)

  10. Chronic exposure to perfluorooctane sulfonate induces behavior defects and neurotoxicity through oxidative damages, in vivo and in vitro.

    Directory of Open Access Journals (Sweden)

    Na Chen

    Full Text Available Perfluorooctane sulfonate (PFOS is an emerging persistent pollutant which shows multiple adverse health effects. However, the neurotoxicity of PFOS and its mechanisms have not been fully elucidated. Using a combination of in vivo and in vitro methods, the present study provides a detailed description of PFOS-induced neurotoxicity. Results showed that the median lethal concentration of PFOS was 2.03 mM in Caenorhabditis elegans for 48 h exposure. 20 µM PFOS caused decrease of locomotor behaviors including forward movement, body bend and head thrash. Additionally, PFOS exposure reduced chemotaxis index of C. elegans, which indicates the decline of chemotaxis learning ability. Using green fluorescent protein (GFP labelled transgenic strains, we found that PFOS caused down-regulated expression of a chemoreceptor gene, gcy-5, in ASE chemosensory neurons, but did not affect cholinergic neurons and dopaminergic neurons. In SH-SY5Y cells, 48 h exposure to 25 µM and 50 µM PFOS induced cell damage, apoptosis and the reactive oxygen species (ROS generation. PFOS caused significant increases of lipid peroxidation and superoxide dismutase activity, but an actual decrease of glutathione peroxidase activity. Furthermore, antioxidant N-acetylcysteine rescued cells from PFOS-induced apoptosis via blocking ROS. Our results demonstrate that chronic exposure to PFOS can cause obvious neurotoxicity and behavior defects. Oxidative damage and anti-oxidative deficit are crucial mechanisms in neurotoxicity of PFOS.

  11. Structure, Raman spectra and defect chemistry modelling of conductive pyrochlore oxides

    DEFF Research Database (Denmark)

    Poulsen, F.W.; Glerup, M.; Holtappels, P.

    2000-01-01

    Mixed ionic-electronic conducting pyrochlore structure oxides, with Pr and Gd on the A site and Zr, Mn, Ce, Sn, In, Mo, and Ti on the B site, were characterised by X-ray powder diffraction and Raman spectroscopy. Mn and In have a solubility around x = 0.1-0.2 in Pr2Zr2-xMnxO7 and Pr2Sn2-xInxO7, r...... for the four equilibrium constants, leading to cases of pure p-type, p- to n-type and pure electrolytic behaviour of doped pyrochlores. (C) 2000 Elsevier Science B.V. All rights reserved....

  12. Generation of highly N-type, defect passivated transition metal oxides using plasma fluorine insertion

    Energy Technology Data Exchange (ETDEWEB)

    Baker, L. Robert; Seo, Hyungtak; Hervier, Antoine; Somorjai, Gabor A.

    2016-04-12

    A new composition of matter is disclosed wherein oxygen vacancies in a semiconducting transition metal oxide such as titanium dioxide are filled with a halogen such as Fluorine, whereby the conductivity of the composition is greatly enhanced, while at the same time the chemical stability of the composition is greatly improved. Stoichiometric titanium dioxide having less than 3 % oxygen vacancies is subject to fluorine insertion such that oxygen vacancies are filled, limited amounts of fluorine replace additional oxygen atoms and fluorine interstitially inserts into the body of the TiO.sub.2 composition.

  13. Oxygen nonstoichiometry, the defect equilibrium model and thermodynamic quantities of the Ruddlesden-Popper oxide Sr3Fe2O(7-δ).

    Science.gov (United States)

    Ling, Yihan; Wang, Fang; Budiman, Riyan Achmad; Nakamura, Takashi; Amezawa, Koji

    2015-03-21

    Oxygen nonstoichiometry of the Ruddlesden-Popper oxide Sr3Fe2O7-δ was measured at intermediate temperatures (773-1073 K) by coulometric titration and high temperature gravimetry. The oxygen nonstoichiometric behavior was analyzed using the defect equilibrium model with localized electrons. From the defect chemical analysis, estimated oxygen vacancy concentration at the O3 sites increases and at the O1 sites decreases with the increasing temperature. This characteristic behavior is considered to be caused by the redistribution of oxygen and vacancies between the O1 and O3 sites. The obtained thermodynamic quantities of the partial molar enthalpy of oxygen, h(O) - h°(O), and the partial molar entropy of oxygen, s(O) - s°(O), calculated from the Gibbs-Helmholtz equation are in good agreement with those from the statistical thermodynamic calculation based on the defect equilibrium model, indicating that the proposed defect equilibrium model is reasonable.

  14. Hepatic oleate regulates adipose tissue lipogenesis and fatty acid oxidation.

    Science.gov (United States)

    Burhans, Maggie S; Flowers, Matthew T; Harrington, Kristin R; Bond, Laura M; Guo, Chang-An; Anderson, Rozalyn M; Ntambi, James M

    2015-02-01

    Hepatic steatosis is associated with detrimental metabolic phenotypes including enhanced risk for diabetes. Stearoyl-CoA desaturases (SCDs) catalyze the synthesis of MUFAs. In mice, genetic ablation of SCDs reduces hepatic de novo lipogenesis (DNL) and protects against diet-induced hepatic steatosis and adiposity. To understand the mechanism by which hepatic MUFA production influences adipose tissue stores, we created two liver-specific transgenic mouse models in the SCD1 knockout that express either human SCD5 or mouse SCD3, that synthesize oleate and palmitoleate, respectively. We demonstrate that hepatic de novo synthesized oleate, but not palmitoleate, stimulate hepatic lipid accumulation and adiposity, reversing the protective effect of the global SCD1 knockout under lipogenic conditions. Unexpectedly, the accumulation of hepatic lipid occurred without induction of the hepatic DNL program. Changes in hepatic lipid composition were reflected in plasma and in adipose tissue. Importantly, endogenously synthesized hepatic oleate was associated with suppressed DNL and fatty acid oxidation in white adipose tissue. Regression analysis revealed a strong correlation between adipose tissue lipid fuel utilization and hepatic and adipose tissue lipid storage. These data suggest an extrahepatic mechanism where endogenous hepatic oleate regulates lipid homeostasis in adipose tissues.

  15. Hydrogen oxidation on gold electrode in perchloric acid solution

    Energy Technology Data Exchange (ETDEWEB)

    Sustersic, M.G.; Almeida, N.V.; Von Mengershausen, A.E. [Facultad de Ingenieria y Ciencias Economico Sociales, Universidad Nacional de San Luis, 25 de Mayo N 384, 5730 Villa Mercedes, San Luis (Argentina)

    2010-06-15

    The aim of this research is to study the interface gold/perchloric acid solution in presence of hydrogen. The reactive is generated by H{sup +} ion reduction and by saturating the electrolyte with the gaseous H{sub 2}. No evidence of H{sub 2} dissociative adsorption is found. In special conditions, a strongly adsorbed layer is formed from the atoms diffusing from inside of the metal. The mass transport occurs in three ways: the diffusion of H atoms inwards, the diffusion of H atoms back to the surface and the dissolved H{sub 2} diffusion from the bulk electrolyte to the surface. When dissolved H{sub 2} reacts, the reaction is kinetically controlled when the H{sub 2} partial pressure is high, and it is diffusionally controlled when the reactive partial pressure is low. Above 0.7 V, (measured vs. RHE), the (100) plane surface reconstruction lifts, and the rate determining step is the H diffusion towards inside of the metal, and the current suddenly falls. The Hydrogen redox reaction on gold shows reversibility with respect to the potential when the reactives are the H diffusing outwards of the metal and the H{sup +} ion present in the electrolyte. However, the absolute current values of oxidation and reduction are different because the reactive sources are different. (author)

  16. Controlled synthesis of nanosized palladium icosahedra and their catalytic activity towards formic-acid oxidation.

    Science.gov (United States)

    Lv, Tian; Wang, Yi; Choi, Sang-Il; Chi, Miaofang; Tao, Jing; Pan, Likun; Huang, Cheng Zhi; Zhu, Yimei; Xia, Younan

    2013-10-01

    Pd icosahedra with sizes controlled in the range of 5-35 nm were synthesized in high purity through a combination of polyol reduction and seed-mediated growth. The Pd icosahedra were obtained with purity >94 % and uniform sizes controlled in the range of 5-17 nm by using ethylene glycol as both the reductant and solvent. The studies indicate that the formation of Pd nanocrystals with an icosahedral shape was very sensitive to the reaction kinetics. The success of this synthesis relies on the use of HCl to manipulate the reaction kinetics and thus control the twin structure and shape of the resultant nanocrystals. The size of the Pd icosahedra could be further increased up to 35 nm by seed-mediated growth, with 17 nm Pd icosahedra serving as seeds. The multiply twinned Pd icosahedra could grow into larger sizes, and their shape and multiply twinned structure were preserved. Thanks to the presence of twin defects, the Pd icosahedra showed a catalytic current density towards formic-acid oxidation that was 1.9 and 11.6 times higher than that of single-crystal Pd octahedra, which were also fully covered by {111} facets, and commercial Pd/C, respectively. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Fasting rapidly increases fatty acid oxidation in white adipose tissue of young broiler chickens.

    Science.gov (United States)

    Torchon, Emmanuelle; Ray, Rodney; Hulver, Matthew W; McMillan, Ryan P; Voy, Brynn H

    2017-01-02

    Upregulating the fatty acid oxidation capacity of white adipose tissue in mice protects against diet-induced obesity, inflammation and insulin resistance. Part of this capacity results from induction of brown-like adipocytes within classical white depots, making it difficult to determine the oxidative contribution of the more abundant white adipocytes. Avian genomes lack a gene for uncoupling protein 1 and are devoid of brown adipose cells, making them a useful model in which to study white adipocyte metabolism in vivo. We recently reported that a brief (5 hour) period of fasting significantly upregulated many genes involved in mitochondrial and peroxisomal fatty acid oxidation pathways in white adipose tissue of young broiler chickens. The objective of this study was to determine if the effects on gene expression manifested in increased rates of fatty acid oxidation. Abdominal adipose tissue was collected from 21 day-old broiler chicks that were fasted for 3, 5 or 7 hours or fed ad libitum (controls). Fatty acid oxidation was determined by measuring and summing (14)CO2 production and (14)C-labeled acid-soluble metabolites from the oxidation of [1-(14)C] palmitic acid. Fasting induced a progressive increase in complete fatty acid oxidation and citrate synthase activity relative to controls. These results confirm that fatty acid oxidation in white adipose tissue is dynamically controlled by nutritional status. Identifying the underlying mechanism may provide new therapeutic targets through which to increase fatty acid oxidation in situ and protect against the detrimental effects of excess free fatty acids on adipocyte insulin sensitivity.

  18. Lack of the P2X7 receptor protects against AMD-like defects and microparticle accumulation in a chronic oxidative stress-induced mouse model of AMD.

    Science.gov (United States)

    Carver, Kyle A; Lin, C M; Bowes Rickman, Catherine; Yang, Dongli

    2017-01-01

    The P2X7 receptor (P2X7R) is an ATP-gated ion channel that is a key player in oxidative stress under pathological conditions. The P2X7R is expressed in the retinal pigmented epithelium (RPE) and neural retina. Chronic oxidative stress contributes to the pathogenesis of age-related macular degeneration (AMD). Mice lacking Cu, Zn superoxide dismutase (Sod1) developed chronic oxidative stress as well as AMD-like features, but whether the P2X7R plays a causative role in oxidative stress-induced AMD is unknown. Thus, the main purpose of this study was to test if concurrent knockout (KO) of P2X7R could block AMD-like defects seen in Sod1 KO mice. Using multiple approaches, we demonstrate that Sod1 KO causes AMD-like defects, including positive staining for oxidative stress markers, 3-nitrotyrosine and carboxymethyl lysine, thinning of the RPE and retina, thickening of Bruch's membrane, presence of basal laminar and linear deposits, RPE barrier disruption and accumulation of microglia/macrophages. Moreover, we find that Sod1 KO mice accumulate more microparticles (MPs) within RPE/choroid tissues. Concurrent KO of the P2X7R protects against AMD-like defects and MP accumulation in Sod1 KO mice. Together, we show for the first time, that deficiency of P2X7R prevents in vivo oxidative stress-induced accumulation of MPs and AMD-like defects. This work could potentially lead to novel therapies for AMD and other oxidative stress-driven diseases.

  19. Neurodegeneration in Friedreich’s Ataxia: From Defective Frataxin to Oxidative Stress

    Directory of Open Access Journals (Sweden)

    Cláudio M. Gomes

    2013-01-01

    Full Text Available Friedreich’s ataxia is the most common inherited autosomal recessive ataxia and is characterized by progressive degeneration of the peripheral and central nervous systems and cardiomyopathy. This disease is caused by the silencing of the FXN gene and reduced levels of the encoded protein, frataxin. Frataxin is a mitochondrial protein that functions primarily in iron-sulfur cluster synthesis. This small protein with an α/β sandwich fold undergoes complex processing and imports into the mitochondria, generating isoforms with distinct N-terminal lengths which may underlie different functionalities, also in respect to oligomerization. Missense mutations in the FXN coding region, which compromise protein folding, stability, and function, are found in 4% of FRDA heterozygous patients and are useful to understand how loss of functional frataxin impacts on FRDA physiopathology. In cells, frataxin deficiency leads to pleiotropic phenotypes, including deregulation of iron homeostasis and increased oxidative stress. Increasing amount of data suggest that oxidative stress contributes to neurodegeneration in Friedreich’s ataxia.

  20. Transformation of Unsaturated Fatty Acids/Esters to Corresponding Keto Fatty Acids/Esters by Aerobic Oxidation with Pd(II)/Lewis Acid Catalyst.

    Science.gov (United States)

    Senan, Ahmed M; Zhang, Sicheng; Zeng, Miao; Chen, Zhuqi; Yin, Guochuan

    2017-08-16

    Utilization of renewable biomass to partly replace the fossil resources in industrial applications has attracted attention due to the limited fossil feedstock with the increased environmental concerns. This work introduced a modified Wacker-type oxidation for transformation of unsaturated fatty acids/esters to the corresponding keto fatty acids/esters, in which Cu(2+) cation was replaced with common nonredox metal ions, that is, a novel Pd(II)/Lewis acid (LA) catalyst. It was found that adding nonredox metal ions can effectively promote Pd(II)-catalyzed oxidation of unsaturated fatty acids/esters to the corresponding keto fatty acids/esters, even much better than Cu(2+), and the promotional effect is highly dependent on the Lewis acidity of added nonredox metal ions. The improved catalytic efficiency is attributed to the formation of heterobimetallic Pd(II)/LA species, and the oxidation mechanism of this Pd(II)/LA catalyst is also briefly discussed.

  1. Comparative Evaluation of Diagnostic Tools for Oxidative Deterioration of Polyunsaturated Fatty Acid-Enriched Infant Formulas during Storage

    Directory of Open Access Journals (Sweden)

    Caroline Siefarth

    2013-12-01

    Full Text Available The challenge in the development of infant formulas enriched with polyunsaturated fatty acids (PUFAs is to meet the consumers’ expectations with regard to high nutritional and sensory value. In particular, PUFAs may be prone to fatty acid oxidation that can generate potential rancid, metallic and/or fishy off-flavors. Although such off-flavors pose no health risk, they can nevertheless lead to rejection of products by consumers. Thus, monitoring autoxidation at its early stages is of great importance and finding a suitable analytical tool to perform these evaluations is therefore of high interest in quality monitoring. Two formulations of infant formulas were varied systematically in their mineral composition and their presence of antioxidants to produce 18 model formulas. All models were aged under controlled conditions and their oxidative deterioration was monitored. A quantitative study was performed on seven characteristic odor-active secondary oxidation products in the formulations via two-dimensional high resolution gas chromatography-mass spectrometry/olfactometry (2D-HRGC-MS/O. The sensitivity of the multi-dimensional GC-MS/O analysis was supported by two additional analytical tools for monitoring autoxidation, namely the analysis of lipid hydroperoxides and conjugated dienes. Furthermore, an aroma profile analysis (APA was performed to reveal the presence and intensities of typical odor qualities generated in the course of fatty acid oxidation. The photometrical analyses of lipid hydroperoxides and conjugated dienes were found to be too insensitive for early indication of the development of sensory defects. By comparison, the 2D-HRGC-MS/O was capable of monitoring peroxidation of PUFAs at low ppb-level in its early stages. Thereby, it was possible to screen oxidative variances on the basis of such volatile markers already within eight weeks after production of the products, which is an earlier indication of oxidative deterioration

  2. Photocatalytic oxidation of humic acid and its effect on haloacetic acid formation potential: a fluorescence spectrometry study.

    Science.gov (United States)

    Xiaoju, Yan; Ruiling, Bao; Shuili, Yu; Qiongfang, Li; Wei, Chen

    2012-01-01

    By fluorescence spectrometry method, molecular conformation changes of humic acid (HA) during the photocatalytic oxidation process were studied. Haloacetic acids formation potential (HAAFP) changes during the oxidation process were also measured. The results indicated that aromatic rings of HA decreased and conjugated double bonds were destroyed at the beginning of the process. Meanwhile, organic matter with large molecular weight decomposed into intermediates with smaller molecular weight, such as tryptophan and tyrosine. HA can be degraded almost completely, but not be mineralized thoroughly. Structures of the intermediates were changing during the oxidation process. Molecular structure transformation of HA led to the fluctuation tendency of the HAAFP changes during the photocatalytic oxidation process. HAAFP increased to 1.22 times that in raw water after 30 min of ultraviolet (UV) radiation, and decreased to 0.66 times that in raw water after 60 min of photocatalytic oxidation.

  3. Evaluation of effectiveness of hyaluronic acid in combination with bioresorbable membrane (poly lactic acid-poly glycolic acid for the treatment of infrabony defects in humans: A clinical and radiographic study

    Directory of Open Access Journals (Sweden)

    Bhumika Sehdev

    2016-01-01

    Full Text Available Background: The combination of biomaterials, bone graft substitutes along with guided tissue regeneration (GTR has been shown to be an effective modality of periodontal regenerative therapy for infrabony defects. Therefore, the present randomized controlled clinical study was undertaken to evaluate the effectiveness of hyaluronic acid (HA in combination with bioresorbable membrane for the treatment of human infrabony defects. Materials and Methods: Twenty four infrabony defects in 20 systemically healthy patients were randomly assigned to test (HA in combination with bioresorbable membrane and control (bioresorbable membrane alone treatment groups. Probing pocket depth (PPD, relative attachment level, and relative gingival margin level were measured with a computerized Florida disc probe at baseline and at 6 months follow-up. Radiographic measurements were also evaluated at baseline and at 6 months of postsurgery. Results: At 6 months, the mean reduction in PPD in test group and control group was 4.52 mm and 2.97 mm, respectively. Significantly higher clinical attachment level with a gain of 2.20 mm was found in the test group as compared to control group. In addition, statistically significant greater reduction of radiographic defect depth was observed in the test group. Conclusion: Regenerative approach using hyaloss in combination with GTR for the treatment of human infrabony defects resulted in a significant added benefit in terms of CAL gains, PPD reductions and radiographic defect fill, as well as LBG, compared to the GTR alone.

  4. Ascorbic acid protects lipids in human plasma and low-density lipoprotein against oxidative damage

    Energy Technology Data Exchange (ETDEWEB)

    Frei, B. (Department of Nutrition, Harvard School of Public Health, Boston, MA (Unites States))

    1991-12-01

    The authors exposed human blood plasma and low-density lipoprotein (LDL) to many different oxidative challenges and followed the temporal consumption of endogenous antioxidants in relation to the initiation of oxidative damage. Under all types of oxidizing conditions, ascorbic acid completely protects lipids in plasma and LDL against detectable peroxidative damage as assessed by a specific and highly sensitive assay for lipid peroxidation. Ascorbic acid proved to be superior to the other water-soluble plasma antioxidants bilirubin, uric acid, and protein thiols as well as to the lipoprotein-associated antioxidants alpha-tocopherol, ubiquinol-10, lycopene, and beta-carotene. Although these antioxidants can lower the rate of detectable lipid peroxidation, they are not able to prevent its initiation. Only ascorbic acid is reactive enough to effectively intercept oxidants in the aqueous phase before they can attack and cause detectable oxidative damage to lipids.

  5. Micelle-assisted signaling of peracetic acid by the oxidation of pyreneboronic acid via monomer-excimer switching.

    Science.gov (United States)

    Choi, Jiyoung; Lee, Hyo Jin; Cho, Min Jeoung; Chang, Suk-Kyu

    2015-08-15

    A simple fluorescent probe for the industrial oxidant peracetic acid (PAA) was investigated. PAA-assisted oxidative conversion of pyrene-1-boronic acid into 1-hydroxypyrene was used as the signaling tool. Pyreneboronic acid was found to display selective signaling behavior, being more responsive to PAA than to other commonly used practical oxidants such as H2O2 and HOCl. The changes in pyrene monomer fluorescence to excimer were used in the quantitative analysis of PAA. When using the surfactant hexadecyltrimethylammonium bromide as a micellar additive, the signaling of PAA was markedly enhanced. Selective fluorescence signaling of PAA by pyrene-1-boronic acid with a detection limit of 1.5×10(-6)M in aqueous environment was successfully achieved.

  6. In vitro studies on the oxidation of medium-chain dicarboxylic acids in rat liver.

    Science.gov (United States)

    Kølvraa, S; Gregersen, N

    1986-05-21

    The degradation of medium-chained dicarboxylic (DC) acids was investigated on purified mitochondria and peroxisomes. Intact organelles were incubated with dodecanedioic acid (DC12), suberic acid (DC8) and adipic acid (DC6), and the production of lower-chained DC-acids and of acetyl-CoA + acetyl-carnitine was monitored. It was shown, that intact peroxisomes could beta-oxidize DC12, DC10, and DC8 at least as far as DC6, while intact mitochondria readily beta-oxidized DC12, and DC10 as far as succinic acid. DC8 and DC6 were not oxidized by intact mitochondria when these two acids were presented externally to the intact organelle. When they were formed intramitochondrially from DC12 and DC10, both DC8 and DC6 were, however, to a great extent beta-oxidized as far as succinic acid. The major reason for this difference between mitochondrial oxidation of externally and internally located DC8 and DC6 seems to be an inability to transport these two acids through the mitochondrial membrane. For DC12 and DC10, the mitochondrial transport systems, which were indicated to be identical to the systems used by the corresponding monocarboxylic acids, were found to be rate-limiting in the beta-oxidation of these acids. A contributing factor to the undetectable beta-oxidation of externally located DC8 and DC6 may also be, that the Km values of DC8-CoA (460 +/- 70 mumol/l) and DC6-CoA (980 +/- 90 mumol/l) towards the acyl-CoA dehydrogenases are very high. These results imply that very high concentrations of intermediates are created intramitochondrially during beta-oxidation, concentrations which are probably only formed through formation of DC8-CoA and DC6-CoA from longer DC-acids and not by transport from outside the mitochondria. The data presented thus for the first time give evidence to a pathway for medium-chained monocarboxylic acids (especially lauric acid and decanoic acid) through cytosolic omega-oxidation followed by activation, transport over the mitochondrial membrane and

  7. The effects of L-carnitine and alpha-tocopherol on acid excretion defect during the acute ureteral obstruction in anaesthetized rats

    Directory of Open Access Journals (Sweden)

    Ashtiyani SC

    2010-01-01

    Full Text Available "n Normal 0 false false false EN-US X-NONE AR-SA MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Arial; mso-bidi-theme-font:minor-bidi;} Background: Ureteral obstruction has been shown to induce renal oxidative stress, suppressed energy metabolism and defected acid excretion. This study was aimed to examine the improving effects of L-carnitine, a facilitating cofactor for mitochondrial oxidation of fatty-acids as well as a scavenger of free-radicals, and a-tocopherol as the most potent antioxidant on these renal disorders at early hours following release of unilateral ureteral obstruction. "n"nMethods: The left ureter was ligated in 60 anaesthetised rats, L-carnitine, a-tocopherol, or their vehicles (normal saline and olive oil, respectively were injected (i.p. in four groups. Each rat was re-anesthetized and cannulated, and ureteral legation was released at exactly 24h after UUO-induction. A 30-min clearance period performed to separately collect urine from both kidneys. The collected urine and arterial blood samples were given to pH-gas analyzer and autoanalyzer, and malondialdehyde (MDA, ATP and ADP levels were assessed in preserved kidneys. There were also sham and control groups (n=8-10 in each."n"nResults: In the post-obstructed kidney of vehicle-treated groups with respect to the equivalent kidney of sham group, there were increases in MDA (p<0

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

    Science.gov (United States)

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

    2012-12-01

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

  9. The use of ascorbate as an oxidation inhibitor in prebiotic amino acid synthesis: a cautionary note.

    Science.gov (United States)

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

    2012-12-01

    It is generally thought that the terrestrial atmosphere at the time of the origin of life was CO(2)-rich and that organic compounds such as amino acids would not have been efficiently formed abiotically under such conditions. It has been pointed out, however, that the previously reported low yields of amino acids may have been partially due to oxidation by nitrite/nitrate during acid hydrolysis. Specifically, the yield of amino acids was found to have increased significantly (by a factor of several hundred) after acid hydrolysis with ascorbic acid as an oxidation inhibitor. However, it has not been shown that CO(2) was the carbon source for the formation of the amino acids detected after acid hydrolysis with ascorbic acid. We therefore reinvestigated the prebiotic synthesis of amino acids in a CO(2)-rich atmosphere using an isotope labeling experiment. Herein, we report that ascorbic acid does not behave as an appropriate oxidation inhibitor, because it contributes amino acid contaminants as a consequence of its reactions with the nitrogen containing species and formic acid produced during the spark discharge experiment. Thus, amino acids are not efficiently formed from a CO(2)-rich atmosphere under the conditions studied.

  10. Knowledge and use of folic acid for prevention of birth defects amongst Honduran women.

    Science.gov (United States)

    Wu, D Ying; Brat, Gabriel; Milla, Gayle; Kim, Jae

    2007-06-01

    To characterize determinants of folic acid (FA) use among women of reproductive age and patient education practices of health care professionals in one region of Honduras. 508 female outpatients and 128 health workers were interviewed in six primary care clinics in Honduras. Results were analyzed using univariate and multivariate regression models. The survey showed that 45% patients were familiar with FA. Of that number, 30% knew appropriate timing of consumption and 25% reported proper pre-natal supplementation. Increasing education was strongly correlated with knowledge of folic acid function (OR=252.52, Pknowledge of proper timing of FA usage (OR=3.94, Pfolic acid with their patients, particularly those of low education and at the extremes of reproductive age. While long-term efforts to develop fortification programs continue, interim Honduran health campaigns to increase proper consumption of folic acid should target these particularly vulnerable populations.

  11. Overexpression of Fatty-Acid-β-Oxidation-Related Genes Extends the Lifespan of Drosophila melanogaster

    Directory of Open Access Journals (Sweden)

    Shin-Hae Lee

    2012-01-01

    Full Text Available A better understanding of the aging process is necessary to ensure that the healthcare needs of an aging population are met. With the trend toward increased human life expectancies, identification of candidate genes affecting the regulation of lifespan and its relationship to environmental factors is essential. Through misexpression screening of EP mutant lines, we previously isolated several genes extending lifespan when ubiquitously overexpressed, including the two genes encoding the fatty-acid-binding protein and dodecenoyl-CoA delta-isomerase involved in fatty-acid β-oxidation, which is the main energy resource pathway in eukaryotic cells. In this study, we analyzed flies overexpressing the two main components of fatty-acid β-oxidation, and found that overexpression of fatty-acid-β-oxidation-related genes extended the Drosophila lifespan. Furthermore, we found that the ability of dietary restriction to extend lifespan was reduced by the overexpression of fatty-acid-β-oxidation-related genes. Moreover, the overexpression of fatty-acid-β-oxidation-related genes enhanced stress tolerance to oxidative and starvation stresses and activated the dFOXO signal, indicating translocation to the nucleus and transcriptional activation of the dFOXO target genes. Overall, the results of this study suggest that overexpression of fatty-acid-β-oxidation-related genes extends lifespan in a dietary-restriction-related manner, and that the mechanism of this process may be related to FOXO activation.

  12. Knowledge and peri-conceptional use of folic acid in ethnic communities in the UK for the prevention of Neural Tube Defects

    OpenAIRE

    Peake, J; Copp, AJ; Shawe, J

    2013-01-01

    BACKGROUND: It is widely accepted that periconceptional supplementation with folic acid can prevent a significant proportion of neural tube defects (NTDs). The present study evaluated how folic acid knowledge and periconceptional use for NTD prevention varies by ethnicity in the United Kingdom (U.K.). METHODS: A literature search was conducted to identify studies that included assessment of folic acid knowledge or use in U.K. women of different ethnicities. Only research and referenced source...

  13. Fundamental Studies of Irradiation-Induced Defect Formation and Fission Product Dynamics in Oxide Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Stubbins, James

    2012-12-19

    The objective of this research program is to address major nuclear fuels performance issues for the design and use of oxide-type fuels in the current and advanced nuclear reactor applications. Fuel performance is a major issue for extending fuel burn-up which has the added advantage of reducing the used fuel waste stream. It will also be a significant issue with respect to developing advanced fuel cycle processes where it may be possible to incorporate minor actinides in various fuel forms so that they can be 'burned' rather than join the used fuel waste stream. The potential to fission or transmute minor actinides and certain long-lived fission product isotopes would transform the high level waste storage strategy by removing the need to consider fuel storage on the millennium time scale.

  14. Impact of acid and oxidative modifications, single or dual, of sorghum starch on biodegradable films.

    Science.gov (United States)

    Biduski, Bárbara; Silva, Francine Tavares da; Silva, Wyller Max da; Halal, Shanise Lisie de Mello El; Pinto, Vania Zanella; Dias, Alvaro Renato Guerra; Zavareze, Elessandra da Rosa

    2017-01-01

    The objective of this study was to evaluate the effects of acid and oxidation modifications on sorghum starch, as well as the effect of dual modification of starch on the physical, morphological, mechanical, and barrier properties of biodegradable films. The acid modification was performed with 3% lactic acid and the oxidation was performed with 1.5% active chlorine. For dual modification, the acid modification was performed first, followed by oxidation under the same conditions as above. Both films of the oxidized starches, single and dual, had increased stiffness, providing a higher tensile strength and lower elongation when compared to films based on native and single acid modified starches. However, the dual modification increased the water vapor permeability of the films without changing their solubility. The increase in sorghum starch concentration in the filmogenic solution increased the thickness, water vapor permeability, and elongation of the films.

  15. Oxidation of nonplasma fatty acids during exercise is increased in women with abdominal obesity.

    Science.gov (United States)

    Horowitz, J F; Klein, S

    2000-12-01

    We evaluated plasma fatty acid availability and plasma and whole body fatty acid oxidation during exercise in five lean and five abdominally obese women (body mass index = 21 +/- 1 vs. 38 +/- 1 kg/m(2)), who were matched on aerobic fitness, to test the hypothesis that obesity alters the relative contribution of plasma and nonplasma fatty acids to total energy production during exercise. Subjects exercised on a recumbent cycle ergometer for 90 min at 54% of their peak oxygen consumption. Stable isotope tracer methods ([(13)C]palmitate) were used to measure fatty acid rate of appearance in plasma and the rate of plasma fatty acid oxidation, and indirect calorimetry was used to measure whole body substrate oxidation. During exercise, palmitate rate of appearance increased progressively and was similar in obese and lean groups between 60 and 90 min of exercise [3.9 +/- 0.4 vs. 4.0 +/- 0.3 micromol. kg fat free mass (FFM)(-1). min(-1)]. The rate of plasma fatty acid oxidation was also similar in obese and lean subjects (12.8 +/- 1.7 vs. 14.5 +/- 1.8 micromol. kg FFM(-1). min(-1); P = not significant). However, whole body fatty acid oxidation during exercise was 25% greater in obese than in lean subjects (21.9 +/- 1.2 vs. 17.5 +/- 1.6 micromol. kg FFM(-1). min(-1); P obese women, women with abdominal obesity use more fat as a fuel by oxidizing more nonplasma fatty acids.

  16. Prolonged maternal amino acid infusion in late-gestation pregnant sheep increases fetal amino acid oxidation.

    Science.gov (United States)

    Rozance, Paul J; Crispo, Michelle M; Barry, James S; O'Meara, Meghan C; Frost, Mackenzie S; Hansen, Kent C; Hay, William W; Brown, Laura D

    2009-09-01

    Protein supplementation during human pregnancy does not improve fetal growth and may increase small-for-gestational-age birth rates and mortality. To define possible mechanisms, sheep with twin pregnancies were infused with amino acids (AA group, n = 7) or saline (C group, n = 4) for 4 days during late gestation. In the AA group, fetal plasma leucine, isoleucine, valine, and lysine concentrations were increased (P < 0.05), and threonine was decreased (P < 0.05). In the AA group, fetal arterial pH (7.365 +/- 0.007 day 0 vs. 7.336 +/- 0.012 day 4, P < 0.005), hemoglobin-oxygen saturation (46.2 +/- 2.6 vs. 37.8 +/- 3.6%, P < 0.005), and total oxygen content (3.17 +/- 0.17 vs. 2.49 +/- 0.20 mmol/l, P < 0.0001) were decreased on day 4 compared with day 0. Fetal leucine disposal did not change (9.22 +/- 0.73 vs. 8.09 +/- 0.63 micromol x min(-1) x kg(-1), AA vs. C), but the rate of leucine oxidation increased 43% in the AA group (2.63 +/- 0.16 vs. 1.84 +/- 0.24 micromol x min(-1) x kg(-1), P < 0.05). Fetal oxygen utilization tended to be increased in the AA group (327 +/- 23 vs. 250 +/- 29 micromol x min(-1) x kg(-1), P = 0.06). Rates of leucine incorporation into fetal protein (5.19 +/- 0.97 vs. 5.47 +/- 0.89 micromol x min(-1) x kg(-1), AA vs. C), release from protein breakdown (4.20 +/- 0.95 vs. 4.62 +/- 0.74 micromol x min(-1) x kg(-1)), and protein accretion (1.00 +/- 0.30 vs. 0.85 +/- 0.25 micromol x min(-1) x kg(-1)) did not change. Consistent with these data, there was no change in the fetal skeletal muscle ubiquitin ligases MaFBx1 or MuRF1 or in the protein synthesis regulators 4E-BP1, eEF2, eIF2alpha, and p70(S6K). Decreased concentrations of certain essential amino acids, increased amino acid oxidation, fetal acidosis, and fetal hypoxia are possible mechanisms to explain fetal toxicity during maternal amino acid supplementation.

  17. Increased hepatic fatty acids uptake and oxidation by LRPPRC-driven oxidative phosphorylation reduces blood lipid levels

    Directory of Open Access Journals (Sweden)

    Ping Zhou

    2016-07-01

    Full Text Available Hyperlipidemia is one of the major risk factors of atherosclerosis and other cardiovascular diseases. This study aimed to investigate the impact of leucine rich pentatricopeptide repeat containing protein (LRPPRC-driven hepatic oxidative phoshorylation on blood lipid levels. The hepatic LRPPRC level was modulated by liver-specific transgenic or adeno-associated virus 8 carried shRNA targeting Lrpprc (aav-shLrpprc. Mice were fed with a high fat diet to induce obesity. Gene expression was analyzed by quantitative real-time PCR and / or western blot. The hepatic ATP level, hepatic and serum lipids contents, and mitochondria oxidative phosphorylation complex activities were measured using specific assay kits. The uptake and oxidation of fatty acid by hepatocytes were assessed using 14C-palmitate. LRPPRC regulated the expression of genes encoded by mitochondrial genome but not those by nuclear genome involved in mitochondria biogenesis, oxidative phosphorylation, and lipid metabolism. Increased oxidative phosphorylation in liver mediated by LRPPRC resulted in the increase of hepatic ATP level. Lrpprc promoted palmitate uptake and oxidation by hypatocytes. The hepatic and serum triglyceride and total cholesterol levels were inversely associated with the hepatic LRPPRC level. These data demonstrated that LRPPRC-driven hepatic oxidative phosphorylation could promote fatty acids uptake and oxidation by hepatocytes and reduce both hepatic and circulating triglyceride and cholesterol levels.

  18. Time resolved study of hydroxyl radical oxidation of oleic acid at the air-water interface

    Science.gov (United States)

    Zhang, Xinxing; Barraza, Kevin M.; Upton, Kathleen T.; Beauchamp, J. L.

    2017-09-01

    The ubiquity of oleic acid (OA) renders it a poster child for laboratory investigations of environmental oxidation chemistry. In the current study, mechanistic details of the oxidation of OA by hydroxyl radicals at the air-water interface are investigated using field-induced droplet ionization mass spectrometry (FIDI-MS). Products from OH oxidation of both unsaturated and saturated carbon atoms are identified, and mechanisms for both types of oxidation processes are proposed. Uptake of oxygen in the interfacial layer increases linearly with time, consistent with Langmuir-Hinshelwood reaction kinetics. These results provide fundamental knowledge relating to OH initiated degradation of fatty acids in atmospheric aerosols.

  19. The rationale for preventing cancer cachexia: targeting excessive fatty acid oxidation.

    Science.gov (United States)

    Qian, Chao-Nan

    2016-07-21

    Cachexia commonly occurs at the terminal stage of cancer and has largely unclear molecular mechanisms. A recent study published in Nature Medicine, entitled "Excessive fatty acid oxidation induces muscle atrophy in cancer cachexia," reveals that cachectic cancer cells can secrete multiple cytokines that induce excessive fatty acid oxidation, which is responsible for muscle loss in cancer cachexia. Inhibition of fatty acid oxidation using etomoxir can increase muscle mass and body weight in cancer cachexia animal models. The usage of stable cachexia animal models is also discussed in this research highlight.

  20. The rationale forpreventing cancer cachexia:targeting excessive fatty acid oxidation

    Institute of Scientific and Technical Information of China (English)

    Chao-Nan Qian

    2016-01-01

    Cachexia commonly occurs at the terminal stage of cancer and has largely unclear molecular mechanisms. A recent study published inNature Medicine, entitled “Excessive fatty acid oxidation induces muscle atrophy in cancer cachexia,”reveals that cachectic cancer cells can secrete multiple cytokines that induce excessive fatty acid oxidation, which is responsible for muscle loss in cancer cachexia. Inhibition of fatty acid oxidation using etomoxir can increase muscle mass and body weight in cancer cachexia animal models. The usage of stable cachexia animal models is also dis‑cussed in this research highlight.

  1. Catalytic air oxidation of biomass-derived carbohydrates to formic acid.

    Science.gov (United States)

    Li, Jiang; Ding, Dao-Jun; Deng, Li; Guo, Qing-Xiang; Fu, Yao

    2012-07-01

    An efficient catalytic system for biomass oxidation to form formic acid was developed. The conversion of glucose to formic acid can reach up to 52% yield within 3 h when catalyzed by 5 mol% of H(5)PV(2)Mo(10)O(40) at only 373 K using air as the oxidant. Furthermore, the heteropolyacid can be used as a bifunctional catalyst in the conversion of cellulose to formic acid (yield=35%) with air as the oxidant. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Treatment of infectious skin defects or ulcers with electrolyzed strong acid aqueous solution.

    Science.gov (United States)

    Sekiya, S; Ohmori, K; Harii, K

    1997-01-01

    A chronic ulcer with an infection such as methicillin-resistant Staphylococcus aureus is hard to heal. Plastic and reconstructive surgeons often encounter such chronic ulcers that are resistant to surgical or various conservative treatments. We applied conservative treatment using an electrolyzed strong acid aqueous solution and obtained satisfactory results. The lesion was washed with the solution or soaked in a bowl of the solution for approximately 20 min twice a day. Fresh electrolyzed strong acid aqueous solution is unstable and should be stored in a cool, dark site in a sealed bottle. It should be used within a week after it has been produced. Here we report on 15 cases of infectious ulcers that were treated by electrolyzed strong acid aqueous solution. Of these cases, 7 patients were healed, 3 were granulated, and in 5, infection subsided. In most cases the lesion became less reddish and less edematous. Discharge or foul odor from the lesion was decreased. Electrolyzed strong acid aqueous solution was especially effective for treating a chronic refractory ulcer combined with diabetes melitus or peripheral circulatory insufficiency. This clinically applied therapy of electrolyzed strong acid aqueous solution was found to be effective so that this new therapeutic technique for ulcer treatment can now be conveniently utilized.

  3. Lipid oxidation in fish oil enriched mayonnaise: calcium disodium ethylenediaminetetraacetate, but not gallic acid, strongly inhibited oxidative deterioration.

    Science.gov (United States)

    Jacobsen, C; Hartvigsen, K; Thomsen, M K; Hansen, L F; Lund, P; Skibsted, L H; Hølmer, G; Adler-Nissen, J; Meyer, A S

    2001-02-01

    The antioxidative effects of gallic acid, EDTA, and extra emulsifier Panodan DATEM TR in mayonnaise enriched with 16% fish oil were investigated. EDTA reduced the formation of free radicals, lipid hydroperoxides, volatiles, and fishy and rancid off-flavors. The antioxidative effect of EDTA was attributed to its ability to chelate free metal ions and iron from egg yolk located at the oil-water interface. Gallic acid reduced the levels of both free radicals and lipid hydroperoxides but promoted slightly the oxidative flavor deterioration in mayonnaise and influenced the profile of volatiles. Gallic acid may therefore promote the decomposition of lipid hydroperoxides to volatile oxidation products. Addition of extra emulsifier reduced the lipid hydroperoxide levels but did not influence the level of free radicals or the oxidative flavor deterioration in mayonnaisse; however, it appeared to alter the profile of volatiles. The effect of the emulsifier on the physical structure and rheological properties depended on the presence of antioxidants.

  4. High glucose-induced oxidative stress represses sirtuin deacetylase expression and increases histone acetylation leading to neural tube defects.

    Science.gov (United States)

    Yu, Jingwen; Wu, Yanqing; Yang, Peixin

    2016-05-01

    Aberrant epigenetic modifications are implicated in maternal diabetes-induced neural tube defects (NTDs). Because cellular stress plays a causal role in diabetic embryopathy, we investigated the possible role of the stress-resistant sirtuin (SIRT) family histone deacetylases. Among the seven sirtuins (SIRT1-7), pre-gestational maternal diabetes in vivo or high glucose in vitro significantly reduced the expression of SIRT 2 and SIRT6 in the embryo or neural stem cells, respectively. The down-regulation of SIRT2 and SIRT6 was reversed by superoxide dismutase 1 (SOD1) over-expression in the in vivo mouse model of diabetic embryopathy and the SOD mimetic, tempol and cell permeable SOD, PEGSOD in neural stem cell cultures. 2,3-dimethoxy-1,4-naphthoquinone (DMNQ), a superoxide generating agent, mimicked high glucose-suppressed SIRT2 and SIRT6 expression. The acetylation of histone 3 at lysine residues 56 (H3K56), H3K14, H3K9, and H3K27, putative substrates of SIRT2 and SIRT6, was increased by maternal diabetes in vivo or high glucose in vitro, and these increases were blocked by SOD1 over-expression or tempol treatment. SIRT2 or SIRT6 over-expression abrogated high glucose-suppressed SIRT2 or SIRT6 expression, and prevented the increase in acetylation of their histone substrates. The potent sirtuin activator (SRT1720) blocked high glucose-increased histone acetylation and NTD formation, whereas the combination of a pharmacological SIRT2 inhibitor and a pan SIRT inhibitor mimicked the effect of high glucose on increased histone acetylation and NTD induction. Thus, diabetes in vivo or high glucose in vitro suppresses SIRT2 and SIRT6 expression through oxidative stress, and sirtuin down-regulation-induced histone acetylation may be involved in diabetes-induced NTDs. The mechanism underlying pre-gestational diabetes-induced neural tube defects (NTDs) is still elusive. Our study unravels a new epigenetic mechanism in which maternal diabetes-induced oxidative stress represses

  5. Pyrite oxidation under simulated acid rain weathering conditions.

    Science.gov (United States)

    Zheng, Kai; Li, Heping; Wang, Luying; Wen, Xiaoying; Liu, Qingyou

    2017-07-31

    We investigated the electrochemical corrosion behavior of pyrite in simulated acid rain with different acidities and at different temperatures. The cyclic voltammetry, polarization curve, and electrochemical impedance spectroscopy results showed that pyrite has the same electrochemical interaction mechanism under different simulated acid rain conditions, regardless of acidity or environmental temperature. Either stronger acid rain acidity or higher environmental temperature can accelerate pyrite corrosion. Compared with acid rain having a pH of 5.6 at 25 °C, the prompt efficiency of pyrite weathering reached 104.29% as the acid rain pH decreased to 3.6, and it reached 125.31% as environmental temperature increased to 45 °C. Increasing acidity dramatically decreases the charge transfer resistance, and increasing temperature dramatically decreases the passivation film resistance, when other conditions are held constant. Acid rain always causes lower acidity mine drainage, and stronger acidity or high environmental temperatures cause serious acid drainage. The natural parameters of latitude, elevation, and season have considerable influence on pyrite weathering, because temperature is an important influencing factor. These experimental results are of direct significance for the assessment and management of sulfide mineral acid drainage in regions receiving acid rain.

  6. A comparison between platelet-rich plasma (PRP and hyaluronate acid on the healing of cartilage defects.

    Directory of Open Access Journals (Sweden)

    Ji Liu

    Full Text Available Platelet-rich plasma (PRP has offered great promise for the treatment of cartilage degradation, and has been proved to have positive effects on the restoration of cartilage lesions. But no comparative work has been done between PRP and hyaluronate acid (HA concerning their restoring effect on cartilage defect, especially by means of animal experiments and histologic assessments. The purpose of the study was to compare the therapeutic effects of P-PRP and HA on osteoarthritis in rabbit knees. Thirty rabbits were used to establish the animal models by creating a cartilage defect of 5 mm in diameter on the condyles of the femurs, and were randomly divided into three groups: the P-PRP group, HA group and the control group. Then each group was treated with P-PRP, HA or saline solution, respectively. Six and twelve weeks later the rabbits were sacrificed and the samples were collected. The platelet number, the concentrations of growth factors of P-PRP and whole blood, and the IL-1β concentration in the joint fluid were investigated, and the histological assessment of the cartilage were performed according to Mankin's scoring system. Micro-CT was also used to evaluate the restoration of subchondral bone. The platelet concentration in P-PRP is 6.8 fold of that in the whole blood. The IL-1β level in the P-PRP group was lower than in the HA group (p<0.01 and in the control group (p<0.01. The restoration of the defected cartilage as well as the subchondral bone was better in the P-PRP group than in the HA group or the control group (P<0.05. Our data showed that P-PRP is better than HA in promoting the restoration of the cartilage and alleviating the arthritis caused by cartilage damage.

  7. Poly(ethylene oxide)-poly(butylene oxide)-poly(ethylene oxide)-templated synthesis of mesoporous alumina: effect of triblock copolymer and acid concentration.

    Science.gov (United States)

    Materna, Kelly L; Grant, Stacy M; Jaroniec, Mietek

    2012-07-25

    Mesoporous alumina was synthesized via a one-pot self-assembly of aluminum isopropoxide and poly(ethylene oxide)-poly(butylene oxide)-poly(ethylene oxide) triblock copolymer in an acidic ethanol solution. The effects of the polymer concentration and nitric acid concentration, independently, on the adsorption properties (such as surface area, pore volume, microporosity, mesoporosity, and pore width) were studied. An increase in the specific surface area and the pore volume was seen for the samples containing a polymer/aluminum isopropoxide wt. ratio up to 0.71 and a polymer/acid wt ratio of 0.88. Titania isopropoxide was also added to the synthesis to illustrate the extension of this approach to alumina-based mixed metal oxides.

  8. Perfluorooctanoic acid exposure triggers oxidative stress in the mouse pancreas

    Directory of Open Access Journals (Sweden)

    Lisa M. Kamendulis

    2014-01-01

    Full Text Available Perfluorooctanoic acid (PFOA is used in the manufacture of many industrial and commercial products. PFOA does not readily decompose in the environment, and is biologically persistent. Human epidemiologic and animal studies suggest that PFOA exposure elicits adverse effects on the pancreas. While multiple animal studies have examined PFOA-mediated toxicity in the liver, little is known about the potential adverse effects of PFOA on the pancreas. To address this, we treated C57Bl/6 mice with vehicle, or PFOA at doses of 0.5, 2.5 or 5.0 mg/kg BW/day for 7 days. Significant accumulation of PFOA was found in the serum, liver and pancreas of PFOA-treated animals. Histopathologic examination of the pancreas revealed focal ductal hyperplasia in mice treated with 2.5 and 5.0 mg/kg BW/day PFOA, while inflammation was observed only in the high dose group. Elevated serum levels of amylase and lipase were observed in the 2.5 mg/kg BW/day PFOA treatment group. In addition, PFOA exposure resulted in a dose-dependent increase in the level of the lipid peroxidation product 8-iso-PGF2α and induction of the antioxidant response genes Sod1, Sod2, Gpx2 and Nqo1. Our findings provide additional evidence that the pancreas is a target organ for PFOA-mediated toxicity and suggest that oxidative stress may be a mechanism through which PFOA induces histopathological changes in the pancreas.

  9. Formic-acid-induced depolymerization of oxidized lignin to aromatics.

    Science.gov (United States)

    Rahimi, Alireza; Ulbrich, Arne; Coon, Joshua J; Stahl, Shannon S

    2014-11-13

    Lignin is a heterogeneous aromatic biopolymer that accounts for nearly 30% of the organic carbon on Earth and is one of the few renewable sources of aromatic chemicals. As the most recalcitrant of the three components of lignocellulosic biomass (cellulose, hemicellulose and lignin), lignin has been treated as a waste product in the pulp and paper industry, where it is burned to supply energy and recover pulping chemicals in the operation of paper mills. Extraction of higher value from lignin is increasingly recognized as being crucial to the economic viability of integrated biorefineries. Depolymerization is an important starting point for many lignin valorization strategies, because it could generate valuable aromatic chemicals and/or provide a source of low-molecular-mass feedstocks suitable for downstream processing. Commercial precedents show that certain types of lignin (lignosulphonates) may be converted into vanillin and other marketable products, but new technologies are needed to enhance the lignin value chain. The complex, irregular structure of lignin complicates chemical conversion efforts, and known depolymerization methods typically afford ill-defined products in low yields (that is, less than 10-20wt%). Here we describe a method for the depolymerization of oxidized lignin under mild conditions in aqueous formic acid that results in more than 60wt% yield of low-molecular-mass aromatics. We present the discovery of this facile C-O cleavage method, its application to aspen lignin depolymerization, and mechanistic insights into the reaction. The broader implications of these results for lignin conversion and biomass refining are also considered.

  10. Formic-acid-induced depolymerization of oxidized lignin to aromatics

    Science.gov (United States)

    Rahimi, Alireza; Ulbrich, Arne; Coon, Joshua J.; Stahl, Shannon S.

    2014-11-01

    Lignin is a heterogeneous aromatic biopolymer that accounts for nearly 30% of the organic carbon on Earth and is one of the few renewable sources of aromatic chemicals. As the most recalcitrant of the three components of lignocellulosic biomass (cellulose, hemicellulose and lignin), lignin has been treated as a waste product in the pulp and paper industry, where it is burned to supply energy and recover pulping chemicals in the operation of paper mills. Extraction of higher value from lignin is increasingly recognized as being crucial to the economic viability of integrated biorefineries. Depolymerization is an important starting point for many lignin valorization strategies, because it could generate valuable aromatic chemicals and/or provide a source of low-molecular-mass feedstocks suitable for downstream processing. Commercial precedents show that certain types of lignin (lignosulphonates) may be converted into vanillin and other marketable products, but new technologies are needed to enhance the lignin value chain. The complex, irregular structure of lignin complicates chemical conversion efforts, and known depolymerization methods typically afford ill-defined products in low yields (that is, less than 10-20wt%). Here we describe a method for the depolymerization of oxidized lignin under mild conditions in aqueous formic acid that results in more than 60wt% yield of low-molecular-mass aromatics. We present the discovery of this facile C-O cleavage method, its application to aspen lignin depolymerization, and mechanistic insights into the reaction. The broader implications of these results for lignin conversion and biomass refining are also considered.

  11. Impact of an online educational program on pharmacy students' knowledge of folic acid and neural tube defects.

    Science.gov (United States)

    Bykhovsky, Margarita; Meier, Mary Frances K; Mager, Natalie A DiPietro

    2014-10-01

    Pharmacy students must receive adequate training regarding folic acid for the prevention of neural tube defects (NTDs). Pharmacy students' knowledge should be evaluated and effective methods utilized to improve it, if needed. The objective of this study was to assess baseline knowledge among third-year students in a 0-6 Doctor of Pharmacy program and to evaluate the impact of an online educational video. Baseline knowledge was assessed by a pretest adapted with permission from the March of Dimes (MOD). Students watched a 30-minute MOD video and completed a posttest. Nine months later, students completed a longitudinal posttest. Analysis of variance was used to assess differences in the percentage of correct responses to each question. A total of 133 (90.5%) students completed the educational program and 105 (78.9%) completed the longitudinal test. Statistically significant improvements in knowledge from baseline were seen for 9 of 10 questions on the posttest and for 6 of 10 questions on the longitudinal test. Online videos are tools to teach pharmacy students key information regarding folic acid and NTD; however, material should be reinforced in experiential education as well. Counseling women of childbearing potential about folic acid fulfills an important public health need. © The Author(s) 2014.

  12. Effectiveness of Folic Acid Fortified Flour for Prevention of Neural Tube Defects in a High Risk Region.

    Science.gov (United States)

    Wang, Haochen; De Steur, Hans; Chen, Gong; Zhang, Xiaotian; Pei, Lijun; Gellynck, Xavier; Zheng, Xiaoying

    2016-03-09

    Despite efforts to tackle folate deficiency and Neural Tube Defects (NTDs) through folic acid fortification, its implementation is still lacking where it is needed most, highlighting the need for studies that evaluate the effectiveness of folic acid fortified wheat flour in a poor, rural, high-risk, NTD region of China. One of the most affected regions, Shanxi Province, was selected as a case study. A community intervention was carried out in which 16,648 women of child-bearing age received fortified flour (eight villages) and a control group received ordinary flour (three villages). NTD birth prevalence and biological indicators were measured two years after program initiation at endline only. The effect on the NTD burden was calculated using the disability-adjusted life years (DALYs) method. In the intervention group, serum folate level was higher than in the control group. NTDs in the intervention group were 68.2% lower than in the control group (OR = 0.313, 95% CI = 0.207-0473, p < 0.001). In terms of DALYs, burden in intervention group was approximately 58.5% lower than in the control group. Flour fortification was associated with lower birth prevalence and burden of NTDs in economically developing regions with a high risk of NTDs. The positive findings confirm the potential of fortification when selecting an appropriate food vehicle and target region. As such, this study provides support for decision makers aiming for the implementation of (mandatory) folic acid fortification in China.

  13. Effectiveness of Folic Acid Fortified Flour for Prevention of Neural Tube Defects in a High Risk Region

    Directory of Open Access Journals (Sweden)

    Haochen Wang

    2016-03-01

    Full Text Available Despite efforts to tackle folate deficiency and Neural Tube Defects (NTDs through folic acid fortification, its implementation is still lacking where it is needed most, highlighting the need for studies that evaluate the effectiveness of folic acid fortified wheat flour in a poor, rural, high-risk, NTD region of China. One of the most affected regions, Shanxi Province, was selected as a case study. A community intervention was carried out in which 16,648 women of child-bearing age received fortified flour (eight villages and a control group received ordinary flour (three villages. NTD birth prevalence and biological indicators were measured two years after program initiation at endline only. The effect on the NTD burden was calculated using the disability-adjusted life years (DALYs method. In the intervention group, serum folate level was higher than in the control group. NTDs in the intervention group were 68.2% lower than in the control group (OR = 0.313, 95% CI = 0.207–0473, p < 0.001. In terms of DALYs, burden in intervention group was approximately 58.5% lower than in the control group. Flour fortification was associated with lower birth prevalence and burden of NTDs in economically developing regions with a high risk of NTDs. The positive findings confirm the potential of fortification when selecting an appropriate food vehicle and target region. As such, this study provides support for decision makers aiming for the implementation of (mandatory folic acid fortification in China.

  14. Photo-oxidation of Acetone to Formic Acid in Synthetic Air and Its Atmospheric Implication.

    Science.gov (United States)

    Chattopadhyay, Aparajeo; Chatterjee, Piyali; Chakraborty, Tapas

    2015-07-23

    Acetone photo-oxidation in synthetic air under exposure of 311 nm ultraviolet light has been studied, and the photo-oxidation products are identified by means of infrared spectroscopy. Analysis reveals that formic acid is one of the major products, although there have been debates in the past concerning the authenticity of formation of this acid in synthetic air via the photo-oxidation pathway. The quantum yield of formation of this acid is similar to that of other major photoproducts like methanol, formaldehyde, and carbon monoxide. The reaction yield, however, decreases with an increase in total air pressure in the reaction cell, but it is still significant at pressures relevant to tropospheric conditions. A kinetic model has been used to simulate the measured reaction kinetics, and the quantum yields predicted by the model are found to be consistent with the measured yields for different durations of light exposure. The same model has also been used to investigate the effect of atmospheric nitric oxide on the fate of formation of this acid in the troposphere. Although nitric oxide is known to be a quencher of peroxy radicals, the precursors of formaldehyde and formic acid in acetone photo-oxidation, but our model predicts that this oxide plays a positive role in the overall reaction kinetics for production of this acid in the troposphere.

  15. Integrating nitric oxide into salicylic acid and jasmonic acid/ ethylene plant defense pathways.

    Science.gov (United States)

    Mur, Luis A J; Prats, Elena; Pierre, Sandra; Hall, Michael A; Hebelstrup, Kim H

    2013-01-01

    Plant defense against pests and pathogens is known to be conferred by either salicylic acid (SA) or jasmonic acid (JA)/ethylene (ET) pathways, depending on infection or herbivore-grazing strategy. It is well attested that SA and JA/ET pathways are mutually antagonistic allowing defense responses to be tailored to particular biotic stresses. Nitric oxide (NO) has emerged as a major signal influencing resistance mediated by both signaling pathways but no attempt has been made to integrate NO into established SA/JA/ET interactions. NO has been shown to act as an inducer or suppressor of signaling along each pathway. NO will initiate SA biosynthesis and nitrosylate key cysteines on TGA-class transcription factors to aid in the initiation of SA-dependent gene expression. Against this, S-nitrosylation of NONEXPRESSOR OF PATHOGENESIS-RELATED PROTEINS1 (NPR1) will promote the NPR1 oligomerization within the cytoplasm to reduce TGA activation. In JA biosynthesis, NO will initiate the expression of JA biosynthetic enzymes, presumably to over-come any antagonistic effects of SA on JA-mediated transcription. NO will also initiate the expression of ET biosynthetic genes but a suppressive role is also observed in the S-nitrosylation and inhibition of S-adenosylmethionine transferases which provides methyl groups for ET production. Based on these data a model for NO action is proposed but we have also highlighted the need to understand when and how inductive and suppressive steps are used.

  16. Integrating nitric oxide into salicylic acid and jasmonic acid/ ethylene plant defence pathways.

    Directory of Open Access Journals (Sweden)

    Luis A.J. Mur

    2013-06-01

    Full Text Available Plant defence against pests and pathogens is known to be conferred by either salicylic acid (SA or jasmonic acid (JA/ethylene (ET pathways, depending on infection or herbivore-grazing strategy. It is well attested that SA and JA/ET pathways are mutually antagonistic allowing defence responses to be tailored to particular biotic stresses. Nitric oxide (NO has emerged as a major signal influencing resistance mediated by both signalling pathways but no attempt has been made to integrate NO into established SA/JA/ET interactions. NO has been shown to act as an inducer or suppressor of signalling along each pathway. NO will initiate SA biosynthesis and nitrosylate key cysteines on TGA-class transcription factors to aid in the initiation of SA—dependent gene expression. Against this, S-nitrosylation of NONEXPRESSOR OF PATHOGENESIS-RELATED PROTEINS1 (NPR1 will promote the NPR1 oligomerisation within the cytoplasm to reduce TGA activation. In JA biosynthesis, NO will initiate the expression of JA biosynthetic enzymes, presumably to over-come any antagonistic effects of SA on JA-mediated transcription. NO will also initiate the expression of ET biosynthetic genes but a suppressive role is also observed in the S –nitrosylation and inhibition of s-adenosylmethionine transferases which provides methyl groups for ethylene production. Based on these data a model for NO action is proposed but we have also highlighted the need to understand when and how inductive and suppressive steps are used.

  17. Lipid oxidation stability of omega-3- and conjugated linoleic acid-enriched sous vide chicken meat.

    Science.gov (United States)

    Narciso-Gaytán, C; Shin, D; Sams, A R; Keeton, J T; Miller, R K; Smith, S B; Sánchez-Plata, M X

    2011-02-01

    Lipid oxidation is known to occur rather rapidly in cooked chicken meat containing relatively high amounts of polyunsaturated fatty acids. To assess the lipid oxidation stability of sous vide chicken meat enriched with n-3 and conjugated linoleic acid (CLA) fatty acids, 624 Cobb × Ross broilers were raised during a 6-wk feeding period. The birds were fed diets containing CLA (50% cis-9, trans-11 and 50% trans-10, cis-12 isomers), flaxseed oil (FSO), or menhaden fish oil (MFO), each supplemented with 42 or 200 mg/kg of vitamin E (dl-α-tocopheryl acetate). Breast or thigh meat was vacuum-packed, cooked (74°C), cooled in ice water, and stored at 4.4°C for 0, 5, 10, 15, and 30 d. The lipid oxidation development of the meat was estimated by quantification of malonaldehyde (MDA) values, using the 2-thiobarbituric acid reactive substances analysis. Fatty acid, nonheme iron, moisture, and fat analyses were performed as well. Results showed that dietary CLA induced deposition of cis-9, trans-11 and trans-10, cis-12 CLA isomers, increased the proportion of saturated fatty acids, and decreased the proportions of monounsaturated and polyunsaturated fatty acids. Flaxseed oil induced higher deposition of C18:1, C18:2, C18:3, and C20:4 fatty acids, whereas MFO induced higher deposition of n-3 fatty acids, eicosapentaenoic acid (C20:5), and docosahexaenoic acid (C22:6; P 0.05) lipid oxidation development. In conclusion, dietary CLA, FSO, and MFO influenced the fatty acid composition of chicken muscle and the lipid oxidation stability of meat over the storage time. Supranutritional supplementation of vitamin E enhanced the lipid oxidation stability of sous vide chicken meat.

  18. A comprehensive evaluation of food fortification with folic acid for the primary prevention of neural tube defects

    Directory of Open Access Journals (Sweden)

    Lam Angeline

    2004-09-01

    Full Text Available Abstract Background Periconceptional use of vitamin supplements containing folic acid reduces the risk of a neural tube defect (NTD. In November 1998, food fortification with folic acid was mandated in Canada, as a public health strategy to increase the folic acid intake of all women of childbearing age. We undertook a comprehensive population based study in Newfoundland to assess the benefits and possible adverse effects of this intervention. Methods This study was carried out in women aged 19–44 years and in seniors from November 1997 to March 1998, and from November 2000 to March 2001. The evaluation was comprised of four components: I Determination of rates of NTDs; II Dietary assessment; III Blood analysis; IV Assessment of knowledge and use of folic acid supplements. Results The annual rates of NTDs in Newfoundland varied greatly between 1976 and 1997, with a mean rate of 3.40 per 1,000 births. There was no significant change in the average rates between 1991–93 and 1994–97 (relative risk [RR] 1.01, 95% confidence interval [CI] 0.76–1.34. The rates of NTDs fell by 78% (95% CI 65%–86% after the implementation of folic acid fortification, from an average of 4.36 per 1,000 births during 1991–1997 to 0.96 per 1,000 births during 1998–2001 (RR 0.22, 95% CI 0.14–0.35. The average dietary intake of folic acid due to fortification was 70 μg/day in women aged 19–44 years and 74 μg/day in seniors. There were significant increases in serum and RBC folate levels for women and seniors after mandatory fortification. Among seniors, there were no significant changes in indices typical of vitamin B12 deficiencies, and no evidence of improved folate status masking haematological manifestations of vitamin B12 deficiency. The proportion of women aged 19–44 years taking a vitamin supplement containing folic acid increased from 17% to 28%. Conclusions Based on these findings, mandatory food fortification in Canada should continue at the

  19. In vivo study of microarc oxidation coated biodegradable magnesium plate to heal bone fracture defect of 3mm width.

    Science.gov (United States)

    Wu, Y F; Wang, Y M; Jing, Y B; Zhuang, J P; Yan, J L; Shao, Z K; Jin, M S; Wu, C J; Zhou, Y

    2017-06-23

    Microarc oxidation (MAO) coated magnesium (Mg) with improved corrosion resistance appeal increasing interests as a revolutionary biodegradable metal for fractured bone fixing implants application. However, the in vivo corrosion degradation of the implants and bone healing response are not well understood, which is highly required in clinic. In the present work, 10μm and 20μm thick biocompatible MAO coatings mainly composed of MgO, Mg2SiO4, CaSiO3 and Mg3(PO4)2 phases were fabricated on AZ31 magnesium alloy. The electrochemical tests indicated an improved corrosion resistance of magnesium by the MAO coatings. The 10μm and 20μm coated and uncoated magnesium plates were separately implanted into the radius bone fracture site of adult New Zealand white rabbits using a 3mm width bone fracture defect model to investigate the magnesium implants degradation and uninhibited bone healing. Taking advantage of the good biocompatibility of the MAO coatings, no adverse effects were detected through the blood test and histological examination. The implantation groups of coated and uncoated magnesium plates were both observed the promoting effect of bone fracture healing compared with the simple fracture group without implant. The releasing Mg(2+) by the degradation of implants into the fracture site improved the bone fracture healing, which is attributed to the magnesium promoting CGRP-mediated osteogenic differentiation. Mg degradation and bone fracture healing promoting must be tailored by microarc oxidation coating with different thickness for potential clinic application. Copyright © 2017. Published by Elsevier B.V.

  20. Can folic acid protect against congenital heart defects in Down syndrome?

    NARCIS (Netherlands)

    Meijer, Willemijn M.; Werler, Martha M.; Louik, Carol; Hernandez-Diaz, Sonia; de Jong-van den Berg, Lolkje T. W.; Mitchell, Allen A.

    2006-01-01

    BACKGROUND: Several studies have suggested a protective effect of folic acid (FA) on congenital heart anomalies. Down syndrome (DS) infants are known to have a high frequency of heart anomalies. Not all children with DS suffer from heart anomalies, which raises the question whether maternal factors

  1. Activated Persulfate Oxidation of Perfluorooctanoic Acid (PFOA in Groundwater under Acidic Conditions

    Directory of Open Access Journals (Sweden)

    Penghua Yin

    2016-06-01

    Full Text Available Perfluorooctanoic acid (PFOA is an emerging contaminant of concern due to its toxicity for human health and ecosystems. However, successful degradation of PFOA in aqueous solutions with a cost-effective method remains a challenge, especially for groundwater. In this study, the degradation of PFOA using activated persulfate under mild conditions was investigated. The impact of different factors on persulfate activity, including pH, temperature (25 °C–50 °C, persulfate dosage and reaction time, was evaluated under different experimental conditions. Contrary to the traditional alkaline-activated persulfate oxidation, it was found that PFOA can be effectively degraded using activated persulfate under acidic conditions, with the degradation kinetics following the pseudo-first-order decay model. Higher temperature, higher persulfate dosage and increased reaction time generally result in higher PFOA degradation efficiency. Experimental results show that a PFOA degradation efficiency of 89.9% can be achieved by activated persulfate at pH of 2.0, with the reaction temperature of 50 °C, molar ratio of PFOA to persulfate as 1:100, and a reaction time of 100 h. The corresponding defluorination ratio under these conditions was 23.9%, indicating that not all PFOA decomposed via fluorine removal. The electron paramagnetic resonance spectrometer analysis results indicate that both SO4−• and •OH contribute to the decomposition of PFOA. It is proposed that PFOA degradation occurs via a decarboxylation reaction triggered by SO4−•, followed by a HF elimination process aided by •OH, which produces one-CF2-unit-shortened perfluoroalkyl carboxylic acids (PFCAs, Cn−1F2n−1COOH. The decarboxylation and HF elimination processes would repeat and eventually lead to the complete mineralization all PFCAs.

  2. Bio-based nitriles from the heterogeneously catalyzed oxidative decarboxylation of amino acids.

    Science.gov (United States)

    Claes, Laurens; Matthessen, Roman; Rombouts, Ine; Stassen, Ivo; De Baerdemaeker, Trees; Depla, Diederik; Delcour, Jan A; Lagrain, Bert; De Vos, Dirk E

    2015-01-01

    The oxidative decarboxylation of amino acids to nitriles was achieved in aqueous solution by in situ halide oxidation using catalytic amounts of tungstate exchanged on a [Ni,Al] layered double hydroxide (LDH), NH4 Br, and H2 O2 as the terminal oxidant. Both halide oxidation and oxidative decarboxylation were facilitated by proximity effects between the reactants and the LDH catalyst. A wide range of amino acids was converted with high yields, often >90 %. The nitrile selectivity was excellent, and the system is compatible with amide, alcohol, and in particular carboxylic acid, amine, and guanidine functional groups after appropriate neutralization. This heterogeneous catalytic system was applied successfully to convert a protein-rich byproduct from the starch industry into useful bio-based N-containing chemicals. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. DNA damage and oxidative stress induced by acetylsalicylic acid in Daphnia magna.

    Science.gov (United States)

    Gómez-Oliván, Leobardo Manuel; Galar-Martínez, Marcela; Islas-Flores, Hariz; García-Medina, Sandra; SanJuan-Reyes, Nely

    2014-08-01

    Acetylsalicylic acid is a nonsteroidal anti-inflammatory widely used due to its low cost and high effectiveness. This compound has been found in water bodies worldwide and is toxic to aquatic organisms; nevertheless its capacity to induce oxidative stress in bioindicators like Daphnia magna remains unknown. This study aimed to evaluate toxicity in D. magna induced by acetylsalicylic acid in water, using oxidative stress and DNA damage biomarkers. An acute toxicity test was conducted in order to determine the median lethal concentration (48-h LC50) and the concentrations to be used in the subsequent subacute toxicity test in which the following biomarkers were evaluated: lipid peroxidation, oxidized protein content, activity of the antioxidant enzymes superoxide dismutase, catalase, and glutathione peroxidase, and level of DNA damage. Lipid peroxidation level and oxidized protein content were significantly increased (pacetylsalicylic acid induces oxidative stress and DNA damage in D. magna.

  4. Effect of Oxygen Defects on the Catalytic Performance of VOx/CeO2 Catalysts for Oxidative Dehydrogenation of Methanol

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yan; Wei, Zhehao; Gao, Feng; Kovarik, Libor; Baylon, Rebecca A.; Peden, Charles HF; Wang, Yong

    2015-05-01

    In this work, CeO2 nanocubes with controlled particle size and dominating (100) facets are synthesized as supports for VOx catalysts. Combined TEM, SEM, XRD, and Raman study reveals that the oxygen vacancy density of CeO2 supports can be tuned by tailoring the particle sizes without altering the dominating facets, where smaller particle sizes result in larger oxygen vacancy densities. At the same vanadium coverage, the VOx catalysts supported on small-sized CeO2 supports with higher oxygen defect densities exhibit promoted redox property and lower activation energy for methoxyl group decomposition, as evidenced by H2-TPR and methanol TPD study. These results further confirm that the presence of oxygen vacancies plays an important role in promoting the activity of VOx species in methanol oxidation. We gratefully acknowledge financial support from the U.S. Department of Energy (DOE), Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. Part of this work was conducted in the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by DOE’s Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is a multiprogram national laboratory operated for the DOE by Battelle.

  5. Epididymis response partly compensates for spermatozoa oxidative defects in snGPx4 and GPx5 double mutant mice.

    Directory of Open Access Journals (Sweden)

    Anaïs Noblanc

    Full Text Available We report here that spermatozoa of mice lacking both the sperm nucleus glutathione peroxidase 4 (snGPx4 and the epididymal glutathione peroxidase 5 (GPx5 activities display sperm nucleus structural abnormalities including delayed and defective nuclear compaction, nuclear instability and DNA damage. We show that to counteract the GPx activity losses, the epididymis of the double KO animals mounted an antioxydant response resulting in a strong increase in the global H(2O(2-scavenger activity especially in the cauda epididymis. Quantitative RT-PCR data show that together with the up-regulation of epididymal scavengers (of the thioredoxin/peroxiredoxin system as well as glutathione-S-transferases the epididymis of double mutant animals increased the expression of several disulfide isomerases in an attempt to recover normal disulfide-bridging activity. Despite these compensatory mechanisms cauda-stored spermatozoa of double mutant animals show high levels of DNA oxidation, increased fragmentation and greater susceptibility to nuclear decondensation. Nevertheless, the enzymatic epididymal salvage response is sufficient to maintain full fertility of double KO males whatever their age, crossed with young WT female mice.

  6. Oxidation of resin acids in colophony (rosin) and its implications for patch testing.

    Science.gov (United States)

    Sadhra, S; Foulds, I S; Gray, C N

    1998-08-01

    Commercial preparations of colophony (rosin) used for patch testing are made from unmodified rosin in pet. and may be stored for some considerable time before being used. This would be satisfactory if the composition and dermatological activity of the preparations were both reproducible and stable, but investigations by the authors have shown that the resin acids undergo progressive and substantial oxidation and that the dermatological activity of the preparations increases significantly with time. This may be a cause of inconsistent patch test results unless the composition can be stabilized. Gas liquid chromatography (GLC) analysis of a raw rosin sample and its commercial patch test preparation has shown that they both contained the same resin acids, but the concentration of the abietic type resin acids was found to be lower in the patch test preparations. The degradation of resin acids is due to their atmospheric oxidation, which may occur during the preparation and storage of the commercial rosin patch test preparation. The susceptibility of individual resin acids to atmospheric oxidation was demonstrated by analysing a sample of raw Portuguese gum rosin, which was then left exposed to air and light. Most of the resin acids were found to undergo oxidation at a rate which gradually diminished. More importantly, it is presumed that the concentration of oxidized resin acids increased correspondingly, and these have been shown to be more dermatologically active than the unoxidised resin acids. The rate of decrease of resin acid concentration was found to be in the following order: neoabietic>levopimaric and palustric>abietic>dehydroabetic acid. The pimaric type resin acids were found to be relatively inert to atmospheric oxidation when compared with the abietic type resin acids. Patch testing with the resulting partly oxidized Portuguese rosin produced positive reactions at a 35% higher frequency than the raw Portuguese rosin. The study demonstrates that the

  7. Flavin-catalyzed aerobic oxidation of sulfides and thiols with formic acid/triethylamine.

    Science.gov (United States)

    Murahashi, Shun-Ichi; Zhang, Dazhi; Iida, Hiroki; Miyawaki, Toshio; Uenaka, Masaaki; Murano, Kenji; Meguro, Kanji

    2014-09-14

    An efficient and practical catalytic method for the aerobic oxidative transformation of sulfides into sulfoxides, and thiols into disulfides with formic acid/TEA in the presence of a new, readily available, and stable flavin catalyst 5d is described.

  8. High-efficiency palladium catalysts supported on ppy-modified C60 for formic acid oxidation.

    Science.gov (United States)

    Bai, Zhengyu; Yang, Lin; Guo, Yuming; Zheng, Zhi; Hu, Chuangang; Xu, Pengle

    2011-02-14

    A facile preparation of polypyrrole-modified fullerene supported Pd nanoparticles catalyst is introduced; electrochemical measurements demonstrate that the obtained Pd/ppy-C(60) catalyst shows a good electrocatalytic activity and stability for the oxidation of formic acid.

  9. Hydrogen peroxide and ferulic acid-mediated oxidative cross-linking ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-12-15

    Dec 15, 2009 ... Oxidative cross-linked casein mediated by hydrogen peroxide and ferulic acid was prepared at ... functional properties of food proteins treated (Motoki and. Seguro, 1998 ..... Team of Northeast Agricultural University (No.

  10. Insights into support wettability in tuning catalytic performance in the oxidation of aliphatic alcohols to acids.

    Science.gov (United States)

    Wang, Min; Wang, Feng; Ma, Jiping; Chen, Chen; Shi, Song; Xu, Jie

    2013-07-28

    A superhydrophobic catalyst was prepared by immobilizing Pt nanoparticles on superhydrophobic organic-inorganic hybrid silicas, which showed high activity and selectivity in the oxidation of aliphatic alcohols to carboxylic acids.

  11. Deranged Bioenergetics and Defective Redox Capacity in T Lymphocytes and Neutrophils Are Related to Cellular Dysfunction and Increased Oxidative Stress in Patients with Active Systemic Lupus Erythematosus

    Directory of Open Access Journals (Sweden)

    Ko-Jen Li

    2012-01-01

    Full Text Available Urinary excretion of N-benzoyl-glycyl-Nε-(hexanonyllysine, a biomarker of oxidative stress, was higher in 26 patients with active systemic lupus erythematosus (SLE than in 11 non-SLE patients with connective tissue diseases and in 14 healthy volunteers. We hypothesized that increased oxidative stress in active SLE might be attributable to deranged bioenergetics, defective reduction-oxidation (redox capacity, or other factors. We demonstrated that, compared to normal cells, T lymphocytes (T and polymorphonuclear neutrophils (PMN of active SLE showed defective expression of facilitative glucose transporters GLUT-3 and GLUT-6, which led to increased intracellular basal lactate and decreased ATP production. In addition, the redox capacity, including intracellular GSH levels and the enzyme activity of glutathione peroxidase (GSH-Px and γ-glutamyl-transpeptidase (GGT, was decreased in SLE-T. Compared to normal cells, SLE-PMN showed decreased intracellular GSH levels, and GGT enzyme activity was found in SLE-PMN and enhanced expression of CD53, a coprecipitating molecule for GGT. We conclude that deranged cellular bioenergetics and defective redox capacity in T and PMN are responsible for cellular immune dysfunction and are related to increased oxidative stress in active SLE patients.

  12. Ascorbate and dehydroascorbic acid as reliable biomarkers of oxidative stress

    DEFF Research Database (Denmark)

    Lykkesfeldt, Jens

    2007-01-01

    , the analytical reproducibility was tested by repeated analysis of plasma aliquots from one individual over four years. The plasma was subjected to acidic deproteinization with an equal volume of 10% meta-phosphoric acid containing 2 mM EDTA and analyzed for ascorbate and dehydroascorbic acid by high...

  13. Superiority of DFT+U with non-linear core correction for open-shell binary rare-earth metal oxides: a case study of native point defects in cerium oxides

    Science.gov (United States)

    Huang, Bolong

    2014-09-01

    We successfully proposed a newly corrected density functional theory plus Hubbard U parameter (DFT + U) based on partial core correction on the orbitals within norm-conserving lanthanide atomic pseudopotentials. A related and comprehensive investigation of native point defects in cerium oxides has also been performed as an examine by practice.

  14. A novel application of horseradish peroxidase: Oxidation of alcohol ethoxylate to alkylether carboxylic acid

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A novel application of horseradish peroxidase (HRP) in the oxidation of alcohol ethoxylate to alkylether carboxylie acid in the present of H2O2 was reported in this paper. We propose the mechanism for the catalytic oxidation reaction is that the hydrogen transfers from the substrate to the ferryl oxygen to form the a-hydroxy carbon radical intermediate. The reaction offers a new approach for further research structure and catalytic mechanism of HRP and production of alkylether carboxylic acid.

  15. Characterization of sulfur oxidizing bacteria related to biogenic sulfuric acid corrosion in sludge digesters

    OpenAIRE

    Huber, Bettina;Herzog, Bastian;Drewes, Jörg E.;Koch, Konrad;Müller, Elisabeth

    2017-01-01

    Background Biogenic sulfuric acid (BSA) corrosion damages sewerage and wastewater treatment facilities but is not well investigated in sludge digesters. Sulfur/sulfide oxidizing bacteria (SOB) oxidize sulfur compounds to sulfuric acid, inducing BSA corrosion. To obtain more information on BSA corrosion in sludge digesters, microbial communities from six different, BSA-damaged, digesters were analyzed using culture dependent methods and subsequent polymerase chain reaction denaturing gradient ...

  16. A phosphorylation defective retinoic acid receptor mutant mimics the effects of retinoic acid on EGFR mediated AP-1 expression and cancer cell proliferation

    Directory of Open Access Journals (Sweden)

    Kim Randie

    2002-10-01

    Full Text Available Abstract Background The effects of the vitamin A metabolite retinoic acid (RA are mediated at the transcriptional level by retinoic acid receptors (RAR. These proteins are part of a superfamily of transcription factors which activate target gene expression when bound to their respective ligands. In addition to ligand binding, heterodimerization with transcriptional cofactors and posttranslational modification such as phosphorylation are also critical for transactivation function. Previous studies have shown that phosphorylation of a serine residue at amino acid 77 in the RARα amino terminus was required for basal activation function of the transcription factor. Results We have determined that RA inhibits cyclin H and cdk7 expression thereby decreasing levels of phosphorylated RARα in human cancer cell lines. To determine the effects of decreased RARα phosphorylation in human cancer cells, we stably transfected a phosphorylation defective mutant RARα expression construct into SCC25 cultures. Cells expressing the mutant RARα proliferated more slowly than control clones. This decreased proliferation was associated with increased cyclin dependent kinase inhibitor expression and decreased S phase entry. In the absence of ligand, the RARα mutant inhibited AP-1 activity to an extent similar to that of RA treated control clones. Levels of some AP-1 proteins were inhibited due to decreased EGFR expression upstream in the signaling pathway. Conclusions These results indicate that hypophosphorylated RARα can mimic the anti-AP-1 effects of RA in the absence of ligand.

  17. Intra-articular injection of synovium-derived mesenchymal stem cells and hyaluronic acid promote regeneration of massive cartilage defects in rabbits

    Directory of Open Access Journals (Sweden)

    Vyacheslav Ogay

    2014-01-01

    Full Text Available Introduction: The purpose of this study was to investigate whether intra-articular injection of synovium-derived mesenchymal stem cells (SD MSCs with low molecular weight hyaluronic acid (HA could promote regeneration of massive cartilage in rabbits. Material and methods: The SD MSCs were harvested from the knees of 10 Flemish giant rabbits, expanded in culture, and characterized. A reproducible 4-mm cylindrical defect was created in the intercondylar groove area using a kit for the mosaic chondroplasty of femoral condyle COR (De Puy, Mitek. The defect was made within the cartilage layer without destruction of subchondral bone. Two weeks after the cartilage defect, SD MSCs (2 × 106 cell/0.15 ml were suspended in 0.5% low molecular weight HA (0.15 ml and injected into the left knee, and HA solution (0.30 ml alone was placed into the right knee. Cartilage regeneration in the experimental and control groups were evaluated by macroscopically and histologically at 10, 30, and 60 days. Results: On day 10, after intra-articular injection of SD MSCs, we observed an early process of cartilage regeneration in the defect area. Histological studies revealed that cartilage defect was covered by a thin layer of spindle-shaped undifferentiated cells and proliferated chodroblasts. In contrast, an injection of HA did not induce reparation of cartilage in the defect area. At 30 days, macroscopic observation showed that the size of cartilage defect after SD MSC injection was significantly smaller than after HA injection. Histological score was also better in the MSC- treated intercondylar defect. At 60 days after MSC treatment, cartilage defect was nearly nonexistent and looked similar to an intact cartilage. Conclusion: Thus, intra-articular injection of SD MSCs can adhere to the defect in the intercondylar area, and promote cartilage regeneration in rabbits.

  18. Phytoagents for Cancer Management: Regulation of Nucleic Acid Oxidation, ROS, and Related Mechanisms

    Directory of Open Access Journals (Sweden)

    Wai-Leng Lee

    2013-01-01

    Full Text Available Accumulation of oxidized nucleic acids causes genomic instability leading to senescence, apoptosis, and tumorigenesis. Phytoagents are known to reduce the risk of cancer development; whether such effects are through regulating the extent of nucleic acid oxidation remains unclear. Here, we outlined the role of reactive oxygen species in nucleic acid oxidation as a driving force in cancer progression. The consequential relationship between genome instability and cancer progression highlights the importance of modulation of cellular redox level in cancer management. Current epidemiological and experimental evidence demonstrate the effects and modes of action of phytoagents in nucleic acid oxidation and provide rationales for the use of phytoagents as chemopreventive or therapeutic agents. Vitamins and various phytoagents antagonize carcinogen-triggered oxidative stress by scavenging free radicals and/or activating endogenous defence systems such as Nrf2-regulated antioxidant genes or pathways. Moreover, metal ion chelation by phytoagents helps to attenuate oxidative DNA damage caused by transition metal ions. Besides, the prooxidant effects of some phytoagents pose selective cytotoxicity on cancer cells and shed light on a new strategy of cancer therapy. The “double-edged sword” role of phytoagents as redox regulators in nucleic acid oxidation and their possible roles in cancer prevention or therapy are discussed in this review.

  19. A novel glutathione-hydroxycinnamic acid product generated in oxidative wine conditions.

    Science.gov (United States)

    Bouzanquet, Quentin; Barril, Celia; Clark, Andrew C; Dias, Daniel A; Scollary, Geoffrey R

    2012-12-12

    This study characterizes a novel glutathione-substituted dihydroxyphenyl compound formed during the oxidation of white wine and model wine solutions, which may contribute to the synergistic role of glutathione and hydroxycinnamic acids in delaying oxidative coloration. The critical components for the formation of the compound were found to be hydroxycinnamic acids and glutathione, while ascorbic acid enabled the product to accumulate to higher concentrations. The presence of the wine components important in other wine oxidation mechanisms, (+)-catechin, ethanol and/or tartaric acid, was not essential for the formation of this new compound. Via LC-MS/MS, HR-MS and (1)H NMR (1D and 2D NMR) analyses, the major isomer of the compound formed from glutathione and caffeic acid was found to be 4-[(E)-2'-(S)-glutathionyl ethenyl]-catechol (GEC). Equivalent products were also confirmed via LC-MS/MS for other hydroxycinnamic acids (i.e., ferulic and coumaric acids). Only trace amounts of GEC were formed with the quinic ester of caffeic acid (i.e., chlorogenic acid), and no equivalent product was found for cinnamic acid. GEC was detected in a variety of white wines supplemented with glutathione and caffeic acid. A radical mechanism for the formation of the styrene-glutathione derivatives is proposed.

  20. β-Cyclodextrin promoted oxidation of aldehydes to carboxylic acids in water

    Institute of Scientific and Technical Information of China (English)

    Dong Po Shi; Hong Bing Ji

    2009-01-01

    A facile,efficient and substrate-selective oxidation of aldehydes to carboxylic acids with NaC10 catalyzed by β-cyclodextdn in water has been developed.A series of aldehydes which could form inclusion complex with β-cyclodextrin(β-CD)were oxidized selectively with excellent yields.

  1. Remediation of TCE-contaminated groundwater using acid/BOF slag enhanced chemical oxidation.

    Science.gov (United States)

    Tsai, T T; Kao, C M; Wang, J Y

    2011-04-01

    The objective of this study was to evaluate the potential of applying acid/H(2)O(2)/basic oxygen furnace slag (BOF slag) and acid/S(2)O(8)(2-)/BOF slag systems to enhance the chemical oxidation of trichloroethylene (TCE)-contaminated groundwater. Results from the bench-scale study indicate that TCE oxidation via the Fenton-like oxidation process can be enhanced with the addition of BOF slag at low pH (pH=2-5.2) and neutral (pH=7.1) conditions. Because the BOF slag has iron abundant properties (14% of FeO and 6% of Fe(2)O(3)), it can be sustainably reused for the supplement of iron minerals during the Fenton-like or persulfate oxidation processes. Results indicate that higher TCE removal efficiency (84%) was obtained with the addition of inorganic acid for the activation of Fenton-like reaction compared with the experiments with organic acids addition (with efficiency of 10-15% lower) (BOF slag=10gL(-1); initial pH=5.2). This could be due to the fact that organic acids would compete with TCE for available oxidants. Results also indicate that the pH value had a linear correlation with the observed first-order decay constant of TCE, and thus, lower pH caused a higher TCE oxidation rate.

  2. Catalytic Degradation of Methylphosphonic Acid Using Iron Powder/Iron Oxides

    Science.gov (United States)

    2005-11-01

    aluminium/ aluminium oxide on the degradation of methylphosphonic acid (MPA), the final hydrolysis product of most nerve agents. EGA-FTIR provides... ALUMINIUM OXIDE ) UNDER AIR (BOTTOM). .................. 37 DSTO-TR-1849 1 1. Introduction The Convention on the Prohibition of the...as well as aluminium/ aluminium oxide , using temperature programmed EGA-FTIR. Since MPA is a Schedule II chemical the above requirement can only be

  3. Nitrogen dioxide-dependent oxidation of uric acid in the human oral cavity under acidic conditions: implications for its occurrence in acidic dental plaque.

    Science.gov (United States)

    Takahama, Umeo; Hirota, Sachiko

    2010-06-21

    The pH in dental plaque falls to below 5 after the ingestion of foods, and it may remain low if acid-tolerant bacteria grow in the plaque. Certain nitrate-reducing bacteria in the oral cavity can proliferate in dental plaque at low pH, and nitrite is detected in such plaque. In acidic dental plaque, NO(2) can be produced by self-decomposition of nitrous acid and also by peroxidase-catalyzed oxidation of nitrite, and it may oxidize uric acid, a major antioxidant in the oral cavity. Under experimental conditions that simulate oral cavity, the oxidation of uric acid by nitrite and by nitrite/peroxidase systems was much more rapid at pH 5 than at pH 7, suggesting the more rapid production of NO(2) in dental plaque at lower pH. We propose that if the pH of plaque developed in a dental crevice decreased, NO(2) and other nitrogen oxides produced in the plaque would diffuse into the adjoining gingival tissues. The results of this study seem to contribute to the understanding of the induction of periodontal diseases in the context of nitrite-dependent production of nitrogen oxides in acidic dental plaque.

  4. Atomically Abrupt Liquid-Oxide Interface Stabilized by Self-Regulated Interfacial Defects: The Case of Al/Al2O3 Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kang, J.; Zhu, J. Y.; Curtis, C.; Blake, D.; Glatzmaier, G.; Kim, Y. H.; Wei, S. H.

    2012-06-01

    The atomic and electronic structures of the liquid Al/(0001) {alpha}-Al{sub 2}O{sub 3} interfaces are investigated by first-principles molecular dynamics simulations. Surprisingly, the formed liquid-solid interface is always atomically abrupt and is characterized by a transitional Al layer that contains a fixed concentration of Al vacancies ({approx}10 at.%). We find that the self-regulation of the defect density in the metal layer is due to the fact that the formation energy of the Al vacancies is readjusted in a way that opposes changes in the defect density. The negative-feedback effect stabilizes the defected transitional layer and maintains the atomic abruptness at the interface. The proposed mechanism is generally applicable to other liquid-metal/metal-oxide systems, and thus of significant importance in understanding the interface structures at high temperature.

  5. Effects of folic acid awareness on knowledge and consumption for the prevention of birth defects among Hispanic women in several U.S. Communities.

    Science.gov (United States)

    Prue, Christine E; Hamner, Heather C; Flores, Alina L

    2010-04-01

    The neural tube defects (NTDs) anencephaly and spina bifida, are serious birth defects of the brain and spine that affect about 3000 pregnancies per year in the United States. Research has found a strong link between periconceptional folic acid consumption and NTD prevention. Because Hispanic women have higher rates of NTD-affected births, targeted folic acid promotion efforts were conducted in several major cities from 1999 to 2002. Efforts included paid and unpaid placements of Spanish language public service announcements (PSAs) and community-level education through the use of promotoras. Analyses focused on whether or not women's reported awareness of folic acid, regardless of promotion type, impacted their knowledge or behavior. Women who reported awareness of folic acid had greater folic acid knowledge and use of vitamins containing folic acid than those not aware. Analyses also examined the use of vitamins containing folic acid by pregnancy intention among women who reported awareness of folic acid. The results were varied. Pregnancy wanters were most likely to use vitamins containing folic acid daily. For this group, however, awareness did not play as large a role in whether they reported consuming a vitamin containing folic acid or not, as it did for pregnancy waiters and avoiders.

  6. Folic acid and the prevention of neural tube defects: A survey of awareness among Latina women of childbearing age residing in southeast Michigan.

    Science.gov (United States)

    Kannan, Srimathi; Menotti, Elaine; Scherer, Holly K; Dickinson, Jennifer; Larson, Kimberly

    2007-01-01

    Periconceptional intake of folic acid is known to reduce the risk for neural tube defects (NTDs). To inform southeast Michigan Latina women of childbearing age about the benefits of food and supplemental sources of the micronutrient in the prevention of NTDs, Spanish-English bilingual health educators carried out 20 education events in supermarkets and community organizations serving Latina women. One hundred and sixty Latina women ages 19 to 50 years indicated their current folic acid awareness and stated their future intentions regarding folic acid. Of 160 women surveyed, 114 (71%) had heard of folic acid, 84 (74%) knew that folic acid prevents birth defects, 63 (55%) knew the critical time to take folic acid, and 76 (67%) identified at least one source of folic acid. After participating in the education events, 136 women (85%) reported planning to eat more folate and/or folic acid-rich foods. Although general folic acid awareness is fairly high, health promotion efforts must be coordinated at community locations serving Latina women to share folic acid's specific protective effects in the prevention of NTDs, the critical timing of intake, and its food and supplement sources.

  7. Preparation of nitric humic acid by catalytic oxidation from Guizhou coal with catalysts

    Institute of Scientific and Technical Information of China (English)

    Yang Zhiyuan; Gong Liang; Ran Pan

    2012-01-01

    Nitric humic acid was prepared by catalytic oxidation between nitric acid and Guizhou coal,with added catalysts.We investigated catalytic oxidation processes and the factors that affect the reactions.The effects of different catalysts,including NiSO4 support on active carbon (AC-NiSO4),NiSO4 support on silicon dioxide (SiO2-NiSO4),composites of SO42-/Fe2O3,Zr-iron and vanadium-iron composite were studied.As well.we investigated nitric humic acid yields and the chemical structure of products by element analysis,FT-IR and E4/E6 (an absorbance ratio at wavelengths of 465 and 665 nm of humic acid alkaline extraction solutions).The results show that the catalytic oxidation reaction with added catalysts can increase humic acid yields by 18.7%,16.36%,12.94%,5.61% and 8.59%,respectively.The highest yield of humic acid,i.e.,36.0%,was obtained with AC-NiSO4 as the catalyst.The amounts of C and H decreased with the amount of nitrogen.The increase in the E4/E6 ratio in catalytic oxidation of (Guizhou) coal shows that small molecular weights and high yields of nitric humic acid can be obtained by catalytic oxidation reactions.

  8. Comparison between conjugated linoleic acid and essential fatty acids in preventing oxidative stress in bovine mammary epithelial cells.

    Science.gov (United States)

    Basiricò, L; Morera, P; Dipasquale, D; Tröscher, A; Bernabucci, U

    2017-03-01

    Some in vitro and in vivo studies have demonstrated protective effects of conjugated linoleic acid (CLA) isomers against oxidative stress and lipid peroxidation. However, only a few and conflicting studies have been conducted showing the antioxidant potential of essential fatty acids. The objectives of the study were to compare the effects of CLA to other essential fatty acids on the thiol redox status of bovine mammary epithelia cells (BME-UV1) and their protective role against oxidative damage on the mammary gland by an in vitro study. The BME-UV1 cells were treated with complete medium containing 50 μM of cis-9,trans-11 CLA, trans-10,cis-12 CLA, α-linolenic acid, γ-linolenic acid, and linoleic acid. To assess the cellular antioxidant response, glutathione, NADPH, and γ-glutamyl-cysteine ligase activity were measured 48 h after addition of fatty acids (FA). Intracellular reactive oxygen species and malondialdehyde production were also assessed in cells supplemented with FA. Reactive oxygen species production after 3 h of H2O2 exposure was assessed to evaluate and to compare the potential protection of different FA against H2O2-induced oxidative stress. All FA treatments induced an intracellular GSH increase, matched by high concentrations of NADPH and an increase of γ-glutamyl-cysteine ligase activity. Cells supplemented with FA showed a reduction in intracellular malondialdehyde levels. In particular, CLA isomers and linoleic acid supplementation showed a better antioxidant cellular response against oxidative damage induced by H2O2 compared with other FA. The Authors. Published by the Federation of Animal Science Societies and Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

  9. Biologically relevant oxidants and terminology, classification and nomenclature of oxidatively generated damage to nucleobases and 2-deoxyribose in nucleic acids

    DEFF Research Database (Denmark)

    Cadet, Jean; Loft, Steffen; Olinski, Ryszard

    2012-01-01

    A broad scientific community is involved in investigations aimed at delineating the mechanisms of formation and cellular processing of oxidatively generated damage to nucleic acids. Perhaps as a consequence of this breadth of research expertise, there are nomenclature problems for several of the ...

  10. Measurement of the rates of oxindole-3-acetic acid turnover, and indole-3-acetic acid oxidation in Zea mays seedlings

    Science.gov (United States)

    Nonhebel, H. M.; Bandurski, R. S. (Principal Investigator)

    1986-01-01

    Oxindole-3-acetic acid is the principal catabolite of indole-3-acetic acid in Zea mays seedlings. In this paper measurements of the turnover of oxindole-3-acetic acid are presented and used to calculate the rate of indole-3-acetic acid oxidation. [3H]Oxindole-3-acetic acid was applied to the endosperm of Zea mays seedlings and allowed to equilibrate for 24 h before the start of the experiment. The subsequent decrease in its specific activity was used to calculate the turnover rate. The average half-life of oxindole-3-acetic acid in the shoots was found to be 30 h while that in the kernels had an average half-life of 35h. Using previously published values of the pool sizes of oxindole-3-acetic acid in shoots and kernels from seedlings of the same age and variety, and grown under the same conditions, the rate of indole-3-acetic acid oxidation was calculated to be 1.1 pmol plant-1 h-1 in the shoots and 7.1 pmol plant-1 h-1 in the kernels.

  11. Compromised mitochondrial fatty acid synthesis in transgenic mice results in defective protein lipoylation and energy disequilibrium.

    Directory of Open Access Journals (Sweden)

    Stuart Smith

    Full Text Available A mouse model with compromised mitochondrial fatty acid synthesis has been engineered in order to assess the role of this pathway in mitochondrial function and overall health. Reduction in the expression of mitochondrial malonyl CoA-acyl carrier protein transacylase, a key enzyme in the pathway encoded by the nuclear Mcat gene, was achieved to varying extents in all examined tissues employing tamoxifen-inducible Cre-lox technology. Although affected mice consumed more food than control animals, they failed to gain weight, were less physically active, suffered from loss of white adipose tissue, reduced muscle strength, kyphosis, alopecia, hypothermia and shortened lifespan. The Mcat-deficient phenotype is attributed primarily to reduced synthesis, in several tissues, of the octanoyl precursors required for the posttranslational lipoylation of pyruvate and α-ketoglutarate dehydrogenase complexes, resulting in diminished capacity of the citric acid cycle and disruption of energy metabolism. The presence of an alternative lipoylation pathway that utilizes exogenous free lipoate appears restricted to liver and alone is insufficient for preservation of normal energy metabolism. Thus, de novo synthesis of precursors for the protein lipoylation pathway plays a vital role in maintenance of mitochondrial function and overall vigor.

  12. Label-free amino acid detection based on nanocomposites of graphene oxide hybridized with gold nanoparticles.

    Science.gov (United States)

    Zhang, Qian; Zhang, Diming; Lu, Yanli; Xu, Gang; Yao, Yao; Li, Shuang; Liu, Qingjun

    2016-03-15

    Nanocomposites of graphene oxide and gold nanoparticles (GO/GNPs) were synthesized for label-free detections of amino acids. Interactions between the composites and amino acids were investigated by both naked-eye observation and optical absorption spectroscopy. The GO/GNPs composites displayed apparent color changes and absorption spectra changes in presences of amino acids including glutamate, aspartate, and cysteine. The interaction mechanisms of the composites and amino acids were discussed and explored with sulfhydryl groups and non-α-carboxylic groups on the amino acids. Sensing properties of the composites were tested, while pure gold particles were used as the control. The results suggested that the GO/GNPs composites had better linearity and stability in dose-dependent responses to the amino acids than those of the particles, especially in detections for acidic amino acids. Therefore, the nanocomposites platform can provide a convenient and efficient approach for label-free optical detections of important molecules such as amino acids.

  13. Effect of Sargassum thunbergii on ROS mediated oxidative damage and identification of polyunsaturated fatty acid components.

    Science.gov (United States)

    Kim, Jung-Ae; Kong, Chang-Suk; Kim, Se-Kwon

    2010-05-01

    In this study, we examined protective effect of Sargassum thunbergii on reactive oxygen species (ROS) mediated oxidative stress in cellular systems. In addition, polyunsaturated fatty acids from S. thunbergii were identified and quantified by gas chromatography mass spectroscopy. Intracellular ROS levels were measured using a oxidation sensitive dye, 2',7'-dichlorofluorescein diacetate (DCFH-DA). Treatment with S. thunbergii significantly reduced intracellular ROS mediated cell damage and inhibited myeloperoxidase (MPO) activity assessed in tumor necrosis factor-alpha (TNF-alpha) stimulated human monocytic leukemia in a concentration-dependent manner. Moreover, antioxidative mechanisms by S. thunbergii were evaluated by measuring the expression levels of antioxidative enzymes such as superoxide dismutase (SOD-1), catalase, glutathione peroxidase and glutathione reductase. SOD-1 and glutathione reductase were up-regulated by S. thunbergii. Furthermore, S. thunbergii contains polyunsaturated fatty acids such as arachidonic acid, arachidic acid, palmitic acid, elaidic acid, linoleic acid, stearic acid and cis-5,8,11,14,17-eicosanoic acid. Therefore, these results suggested that S. thunbergii has nutraceutical effectiveness in prevention of ROS-induced tissue damage and potential natural antioxidant related to oxidative stress, which can be traceable to polyunsaturated fatty acids contained in S. thunbergii.

  14. Identification of genes required for secretion of the Francisella oxidative burst-inhibiting acid phosphatase AcpA

    Directory of Open Access Journals (Sweden)

    John S Gunn

    2016-04-01

    Full Text Available Francisella tularensis is a Tier 1 bioterror threat and the intracellular pathogen responsible for tularemia in humans and animals. Upon entry into the host, Francisella uses multiple mechanisms to evade killing. Our previous studies have shown that after entering its primary cellular host, the macrophage, Francisella immediately suppresses the oxidative burst by secreting a series of acid phosphatases including AcpA-B-C and HapA, thereby evading the innate immune response of the macrophage and enhancing survival and further infection. However, the mechanism of acid phosphatase secretion by Francisella is still unknown. In this study, we screened for genes required for AcpA secretion in Francisella. We initially demonstrated that the known secretion systems, the putative Francisella-pathogenicity island (FPI-encoded Type VI secretion system and the Type IV pili, do not secrete AcpA. Using random transposon mutagenesis in conjunction with ELISA, Western blotting and acid phosphatase enzymatic assays, a transposon library of 5450 mutants was screened for strains with a minimum 1.5-fold decrease in secreted (culture supernatant AcpA, but no defect in cytosolic AcpA. Three mutants with decreased supernatant AcpA were identified. The transposon insertion sites of these mutants were revealed by direct genomic sequencing or inverse-PCR and sequencing. One of these mutants has a severe defect in AcpA secretion (at least 85% decrease and is a predicted hypothetical inner membrane protein. Interestingly, this mutant also affected the secretion of the FPI-encoded protein, VgrG. Thus, this screen identified novel protein secretion factors involved in the subversion of host defenses.

  15. Fe(II) Oxidation and Sources of Acidity on Mars

    Science.gov (United States)

    Niles, P. B.; Peretyazkho, T. S.; Sutter, B.

    2017-01-01

    There is an apparent paradox be-tween the evidence that aqueous environments on Mars were predominantly acidic, and the fact that Mars is predominantly a basaltic (and olivine-rich) planet. The problem being that basalt and olivine will act to neutralize acidic solutions they come into contact with, and that there is a lot more basaltic crust on Mars than water or acid. This is especially true if there is an appreciable amount of water available to bring the acid in contact with the basaltic crust. Several hypotheses for ancient mar-tian environments call on long lived groundwater and aqueous systems.

  16. Oxidative stability of milk drinks containing structured lipids produced from sunflower oil and caprylic acid

    DEFF Research Database (Denmark)

    Timm Heinrich, Maike; Xu, Xuebing; Nielsen, Nina Skall;

    2003-01-01

    of adding potential antioxidants EDTA or gallic acid to the milk drink based on SL was investigated. The lipid type significantly affected the oxidative stability of the milk drinks: Milk drink based on SL oxidized faster than milk drink based on RL or SO. The reduced oxidative stability in the SL milk...... drink could not be ascribed was most likely influenced by the structure of the lipid and to a single factor, differences in the process applied to produce and purify the lipids. EDTA was a strong antioxidant, while gallic acid did not exert a distinct antioxidative effect in the milk drink based on SL....

  17. Influence of Fluorine on the Conductivity and Oxidation of Silicon Nanomembranes after Hydrofluoric Acid Treatment

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xiang-Fu; HAN Ping; ZHANG Rong; ZHENG You-Dou

    2011-01-01

    @@ After immersion in hydrofluoric acid, the sheet resistance of a 220-nm-thick silicon nanomembrane, measured in dry air by van der Pauw method, drops around two orders of magnitude initially, then increases and reaches the level of a sample with a native oxide surface in about one month.The surface component and oxidation rate are also characterized by x-ray photo electronic spectroscopy measurement.Fluorine is found to play a significant role in improving conductivity and has no apparent influence on the oxidation rate after hydrofluoric acid treatment.

  18. Synthesis and characterization of poly acrylic acid/graphite oxide nanocomposite

    Institute of Scientific and Technical Information of China (English)

    胡源; 丁溶芳; 徐加艳; 王清安; 陈祖耀; 范维澄

    2003-01-01

    Acrylic acid-intercalated graphite oxide and poly acrylic acid (PAA)-intercalated graphite oxide were prepared and characterized by X-Ray diffraction (XRD), Fourier transform infrared spectra (FTIR) and high resolution electronic microscope (HREM). Results show that the intercalation process is not only a physical diffusion process but also mainly a chemical reaction process. The high resolution electronic microscope results also reveal that the Ic value of PAA-intercalated graphite oxide (GO) could change widely from 1.6nm to 4.0nm.

  19. Comparative reactivity of the myeloperoxidase-derived oxidants hypochlorous acid and hypothiocyanous acid with human coronary artery endothelial cells.

    Science.gov (United States)

    Lloyd, Mitchell M; Grima, Michael A; Rayner, Benjamin S; Hadfield, Katrina A; Davies, Michael J; Hawkins, Clare L

    2013-12-01

    In the immune response, hypohalous acids are generated by activated leukocytes via the release of myeloperoxidase and the formation of H2O2. Although these oxidants have important bactericidal properties, they have also been implicated in causing tissue damage in inflammatory diseases, including atherosclerosis. Hypochlorous acid (HOCl) and hypothiocyanous acid (HOSCN) are the major oxidants formed by myeloperoxidase under physiological conditions, with the ratio of these oxidants dependent on diet and smoking status. HOCl is highly reactive and causes marked cellular damage, but few data are available on the effects of HOSCN on mammalian cells. In this study, we have compared the actions of HOCl and HOSCN on human coronary artery endothelial cells (HCAEC). HOCl reacts rapidly with the cells, resulting in extensive cell death by both apoptosis and necrosis, with necrosis dominating at higher oxidant doses. In contrast, HOSCN is consumed more slowly, with cell death occurring only by apoptosis. Exposure of HCAEC to HOCl and HOSCN induces changes in mitochondrial membrane permeability, which, in the case of HOSCN, is associated with mitochondrial release of proapoptotic factors, including cytochrome c, apoptosis-inducing factor, and endonuclease G. With each oxidant, apoptosis appears to be caspase-independent, with the inactivation of caspases 3/7 observed, and pretreatment of the cells with the caspase inhibitor Z-VAD-fmk having no effect on the extent of cell death. Loss of cellular thiols, depletion of glutathione, and the inactivation of thiol-dependent enzymes, including glyceraldehyde-3-phosphate dehydrogenase, were seen with both oxidants, though to a much greater extent with HOCl. The ability of myeloperoxidase-derived oxidants to induce endothelial cell apoptosis may contribute to the formation of unstable lesions in atherosclerosis. The results with HOSCN may be particularly significant for smokers, who have elevated plasma levels of SCN(-), the precursor

  20. Biological iron(II) oxidation as pre-treatment to limestone neutralisation of acid water

    CSIR Research Space (South Africa)

    Maree, JP

    1998-01-01

    Full Text Available Iron (II) should be oxidised to iron (III) before the neutralisation of acid water with limestone, otherwise the oxidation will occur downstream of the neutralisation plant with the formation of acid (reactions 1 and 2). This study aimed...

  1. Selective Oxidative Decarboxylation of Amino Acids to Produce Industrially Relevant Nitriles by Vanadium Chloroperoxidase

    NARCIS (Netherlands)

    But, A.; Notre, le J.E.L.; Scott, E.L.; Wever, R.; Sanders, J.P.M.

    2012-01-01

    Industrial nitriles from biomass: Vanadium-chloroperoxidase is successfully used to transform selectively glutamic acid into 3-cyanopropanoic acid, a key intermediate for the synthesis of bio-succinonitrile and bio-acrylonitrile, by using a catalytic amount of a halide salt. This clean oxidative

  2. Natural and pyrogenic humic acids at goethite and natural oxide surfaces interacting with phosphate

    NARCIS (Netherlands)

    Hiemstra, T.; Mia, S.; Duhaut, P.B.; Molleman, B.

    2013-01-01

    Fulvic and humic acids have a large variability in binding to metal (hydr) oxide surfaces and interact differently with oxyanions, as examined here experimentally. Pyrogenic humic acid has been included in our study since it will be released to the environment in the case of large-scale application

  3. Serum uric acid levels and leukocyte nitric oxide production in multiple sclerosis patients outside relapses

    NARCIS (Netherlands)

    Mostert, JP; Ramsaransing, GSM; Heerserna, DJ; Heerings, M; Wilczak, N; De Keyser, J

    2005-01-01

    Background: A number of studies found that patients with multiple sclerosis (MS) have low serum levels of uric acid. It is unclear whether this represents a primary deficit or secondary effect. Uric acid is a scavenger of peroxynitrite, which is the product of nitric oxide (NO) and superoxide. Becau

  4. Selective Oxidative Decarboxylation of Amino Acids to Produce Industrially Relevant Nitriles by Vanadium Chloroperoxidase

    NARCIS (Netherlands)

    But, A.; Notre, le J.E.L.; Scott, E.L.; Wever, R.; Sanders, J.P.M.

    2012-01-01

    Industrial nitriles from biomass: Vanadium-chloroperoxidase is successfully used to transform selectively glutamic acid into 3-cyanopropanoic acid, a key intermediate for the synthesis of bio-succinonitrile and bio-acrylonitrile, by using a catalytic amount of a halide salt. This clean oxidative dec

  5. Primary oxidation and reduction products in x-irradiated aspartic acid

    Energy Technology Data Exchange (ETDEWEB)

    Adams, S.M.; Budzinski, E.E.; Box, H.C.

    1976-08-01

    The primary reduction products identified by ESR--ENDOR spectroscopy in single crystals of DL-aspartic acid hydrochloride irradiated at 4.2degreeK are anions formed by addition of an electron to the carbonyl oxygen atoms of the carboxylic acid groups. The main consequence of the oxidation process is to produce a hole centered mainly on atomic chlorine. (AIP)