Oxidation of Commercial Petronas Diesel with Tert-Butyl Hydroperoxide Over Poly molybdate Alumina Supported Catalyst Modified With Alkaline Earth Metals

International Nuclear Information System (INIS)

Wan Nazwanie Wan Abdullah; Rusmidah Ali; Wan Azlee Wan Abu Bakar

2016-01-01

Due to strict environmental legislation for ultra-low sulfur diesel fuels, increasing technical and operational challenges are imposed to conventional hydrodesulfurization (HDS) technology. Therefore, catalytic oxidative desulfurization (Cat-ODS) has been suggested to be an alternative method to replace a conventional method which is hydrodesulfurization. In this study, catalytic oxidation of commercial diesel was performed using an oil-soluble oxidant, tert-butyl hydroperoxide (TBHP), over poly molybdate supported on alumina MoO_3-PO_4/ Al_2O_3 catalyst. A commercial Petronas diesel with 440 ppm of total sulfur was employed to evaluate the elimination of sulfur compounds. Besides, the percentage of sulfur removal was measured by (GC-FPD). Alkaline earth metals, such as Calcium (Ca), Barium (Ba) and Strontium (Sr) were introduced on the surface of MoO_3-PO_4/ Al_2O_3. The results showed that the catalytic activity decreased in the order, Ca/ MoO_3-PO_4/ Al_2O_3>Sr/ MoO_3-PO_4/ Al_2O_3> Ba/ MoO_3-PO_4/ Al_2O_3. The Ca/ MoO_3-PO_4/ Al_2O_3 catalyst was characterized by XRD and FESEM. XRD results showed that the best catalyst was highly amorphous while FESEM micrograph illustrated an aggregation and agglomeration of various particle sizes. The catalytic activity of Ca/ MoO_3-PO_4/ Al_2O_3 catalyst with various Ca/ Mo ratios were also studied. When the Ca/ Mo ratio was 15:85, the sulfur removal was the highest (79 %) at 45 degree Celsius, 30 min and O/ S molar ratio 3.0 with solvent = dimethylformamide (DMF), diesel/ solvent ratio = 1.0. (author)

Protective Effects of Rooibos (Aspalathus linearis and/or Red Palm Oil (Elaeis guineensis Supplementation on tert-Butyl Hydroperoxide-Induced Oxidative Hepatotoxicity in Wistar Rats

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Olawale R. Ajuwon

2013-01-01

Full Text Available The possible protective effects of an aqueous rooibos extract (Aspalathus linearis, red palm oil (RPO (Elaeis guineensis, or their combination on tert-butyl-hydroperoxide-(t-BHP-induced oxidative hepatotoxicity in Wistar rats were investigated. tert-butyl hydroperoxide caused a significant (P<0.05 elevation in conjugated dienes (CD and malondialdehyde (MDA levels, significantly (P<0.05 decreased reduced glutathione (GSH and GSH : GSSG ratio, and induced varying changes in activities of catalase, superoxide dismutase, glutathione peroxidase, and glutathione reductase in the blood and liver. This apparent oxidative injury was associated with histopathological changes in liver architecture and elevated levels of serum alanine aminotransferase (ALT, aspartate aminotransferase (AST, and lactate dehydrogenase (LDH. Supplementation with rooibos, RPO, or their combination significantly (P<0.05 decreased CD and MDA levels in the liver and reduced serum level of ALT, AST, and LDH. Likewise, changes observed in the activities of antioxidant enzymes and impairment in redox status in the erythrocytes and liver were reversed. The observed protective effects when rooibos and RPO were supplemented concomitantly were neither additive nor synergistic. Our results suggested that rooibos and RPO, either supplemented alone or combined, are capable of alleviating t-BHP-induced oxidative hepatotoxicity, and the mechanism of this protection may involve inhibition of lipid peroxidation and modulation of antioxidants enzymes and glutathione status.

Biomarkers derived from heterolytic and homolytic cleavage of allylic hydroperoxides resulting from alkenone autoxidation

Digital Repository Service at National Institute of Oceanography (India)

Rontania, J.F.; Harji, R.; Volkmanc, J.K.

Laboratory incubation of alkenone mixtures with tert-butyl hydroperoxide and di-tert-butyl nitroxide (radical initiator) in hexane, as a means to simulate alkenone autoxidation processes, rapidly led to the formation of allylic hydroperoxides, whose...

Protective effects of hesperidin against oxidative stress of tert-butyl hydroperoxide in human hepatocytes.

Science.gov (United States)

Chen, Mingcang; Gu, Honggang; Ye, Yiyi; Lin, Bing; Sun, Lijuan; Deng, Weiping; Zhang, Jingzhe; Liu, Jianwen

2010-10-01

Increasing evidence regarding free radical generating agents and the inflammatory process suggest that accumulation of reactive oxygen species (ROS) could involve hepatotoxicity. Hesperidin, a naturally occurring flavonoid presents in fruits and vegetables, has been reported to exert a wide range of pharmacological effects that include antioxidant, anti-inflammatory, antihypercholesterolemic, and anticarcinogenic actions. However, the cytoprotection and mechanism of hesperidin to neutralize oxidative stress in human hepatic L02 cells remain unclear. In this work, we assessed the capability of hesperidin to prevent tert-butyl hydroperoxide (t-BuOOH)-induced cell damage by augmenting cellular antioxidant defense. Hesperidin significantly protected hepatocytes against t-BuOOH-induced cell cytotoxicity, such as mitochondrial membrane potential (MMP) deplete and lactate dehydrogenase (LDH) release. Hesperidin also remarkably prevented indicators of oxidative stress, such as the ROS and lipid peroxidation level in a dose-dependent manner. Western blot showed that hesperidin facilitated ERK/MAPK phosphorylation which appeared to be responsible for nuclear translocation of Nrf2, thereby inducing cytoprotective heme oxygenase-1 (HO-1) expression. Based on the results described above, it suggested that hesperidin has potential as a therapeutic agent in the treatment of oxidative stress-related hepatocytes injury and liver dysfunctions. Copyright © 2010 Elsevier Ltd. All rights reserved.

An efficient and highly selective ortho-tert-butylation of p-cresol with methyl tert-butyl ether catalyzed by sulfonated ionic liquids

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Alamdari Reza Fareghi

2014-01-01

Full Text Available A novel series of sulfonic acid-functionalized ionic liquids (SFILs was found to act as efficient catalysts for ortho-tert-butylation of p-cresol with methyl tert-butyl ether (MTBE as the tert-butylating agent without an added solvent. The mono o-tert-butylated product was obtained in up to 80.4% isolated yield and 95.2% selectivity under such green conditions. No O-tert-butylated byproducts were formed.

Mentha pulegium crude extracts induce thiol oxidation and potentiate hemolysis when associated to t-butyl hydroperoxide in human’s erythrocytes

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MATHEUS C. BIANCHINI

2017-12-01

Full Text Available ABSTRACT Mentha pulegium (Lamiaceae tea has been used as a traditional medicine; however, the modulatory effect of M. pulegium extracts on damage to human erythrocytes associated to t-butyl hydroperoxide (t-BHP exposure remains to be investigated. Accordingly, we perform this study in order to test the hypothesis that aqueous and ethanolic extracts of M. pulegium could modulate the hemolysis associated to t-BHP exposure, non-protein thiol (NPSH oxidation and lipid peroxidation (measured as thiobarbituric acid reactive substances - TBARS in human erythrocytes. Samples were co-incubated with t-BHP (4 mmol/L and/or aqueous or ethanolic extracts (10-1000 mg/mL during 120 min to further analysis. We found that both extracts, when associated to t-BHP, potentiate NPSH oxidation and hemolysis. Moreover, both extracts significantly prevents against t-BHP-induced TBARS production. A significant correlation among hemolysis and NPSH levels was found. Taking together, our data points that the association of M. pulegium extracts with t-BHP culminates in toxic effect to exposed erythrocytes, besides its protective effect against t-BHP-induced TBARS production. So, we infer that the use of this extract may exert negative effect during painful crisis in sickle cell anemia. However, more studies are still necessary to better investigate/understand the mechanism(s involved in the toxic effect resultant from this association.

Base-oxidant promoted metal-free N-demethylation of arylamines

Indian Academy of Sciences (India)

A metal-free oxidative N-demethylation of arylamines with triethylamine as a base and tert-butyl hydroperoxide (TBHP) as oxidant is reported in this paper. The reaction is general, practical, inexpensive, non-toxic, and the method followed is environmentally benign, with moderate to good yields.

The performance of Ti-MCM-41 in aqueous media and after mechanical treatment studied by in situ XANES, UV/Vis and test reactions

DEFF Research Database (Denmark)

Hagen, Anke; Schueler, K.; Roessner, F.

2002-01-01

The influence of water on the epoxidation of cyclohexene with H2O2 and tert-butyl hydroperoxide (tbhp) on Ti-MCM-41 molecular sieves prepared by post-synthetic modification of the support with titanium alkoxides was investigated. The catalytic performance depends on the hydrophilicity/hydrophobic...

Catalytic Activity of μ-Carbido-Dimeric Iron(IV) Octapropylporphyrazinate in the 3,5,7,2',4'-Pentahydroxyflavone Oxidation Reaction with tert-Butyl Hydroperoxide

Science.gov (United States)

Tyurin, D. V.; Zaitseva, S. V.; Kudrik, E. V.

2018-05-01

It is found for the first time that μ-carbido-dimeric iron(IV) octapropylporphyrazinate displays catalytic activity in the oxidation reaction of natural flavonol morin with tert-butyl hydroperoxide, with the catalyst being stable under conditions of the reaction. The kinetics of this reaction are studied. It is shown the reaction proceeds via tentative formation of a complex between the catalyst and the oxidant, followed by O‒O bond homolytic cleavage. The kinetics of the reaction is described in the coordinates of the Michaelis-Menten equation. A linear dependence of the apparent reaction rate constant on the concentration of the catalyst is observed, testifying to its participation in the limiting reaction step. The equilibrium constants and rates of interaction are found. A mechanism is proposed for the reaction on the basis of the experimental data.

Gymnaster koraiensis and its major components, 3,5-di-O-caffeoylquinic acid and gymnasterkoreayne B, reduce oxidative damage induced by tert-butyl hydroperoxide or acetaminophen in HepG2 cells

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Eun Hye Jho

2013-10-01

Full Text Available We investigated the protective effects of Gymnaster koraiensisagainst oxidative stress-induced hepatic cell damage. We usedtwo different cytotoxicity models, i.e., the administration oftert-butyl hydroperoxide (t-BHP and acetaminophen, in HepG2cells to evaluate the protective effects of G. koraiensis. The ethylacetate (EA fraction of G. koraiensis and its major compound,3,5-di-O-caffeoylquinic acid (DCQA, exerted protective effectsin the t-BHP-induced liver cytotoxicity model. The EA fractionand DCQA ameliorated t-BHP-induced reductions in GSHlevels and exhibited free radical scavenging activity. The EAfraction and DCQA also significantly reduced t-BHP-inducedDNA damage in HepG2 cells. Furthermore, the hexane fractionof G. koraiensis and its major compound, gymnasterkoreayne B(GKB, exerted strong hepatoprotection in the acetaminopheninducedcytotoxicity model. CYP 3A4 enzyme activity wasstrongly inhibited by the extract, hexane fraction, and GKB. Thehexane fraction and GKB ameliorated acetaminophen-inducedreductions in GSH levels and protected against cell death. [BMBReports 2013; 46(10: 513-518

Simultaneous analysis of tert-butylhydroquinone, tert-butylquinone, butylated hydroxytoluene, 2-tert-butyl-4-hydroxyanisole, 3-tert-butyl-4-hydroxyanisole, α-tocopherol, γ-tocopherol, and δ-tocopherol in edible oils by normal-phase high performance liquid chromatography.

Science.gov (United States)

Li, Jun; Bi, Yanlan; Sun, Shangde; Peng, Dan

2017-11-01

A normal-phase high performance liquid chromatography method for the simultaneous determination of tert-butylhydroquinone, tert-butylquinone, butylated hydroxytoluene, 2-tert-butyl-4-hydroxyanisole, 3-tert-butyl-4-hydroxyanisole, α-tocopherol, γ-tocopherol, and δ-tocopherol in edible oils was investigated. A silica column was used to separate the analytes with the gradient elution. An ultraviolet-visible detector was set at dual wavelengths mode (280 and 310nm). The column temperature was 30°C. The analytes were directly extracted with methanol. Results showed that the normal-phase high performance liquid chromatography method performed well with wide liner ranges (0.10∼500.00μg/mL, R 2 >0.9998), low limits of detection and quantitation (below 0.40 and 1.21μg/mL, respectively), and good recoveries (81.38∼102.34% in soybean oils and 83.03∼100.79% in lard, respectively). The reduction of tert-butylquinone caused by the reverse-phase high performance liquid chromatography during the injection was avoided with the current normal-phase method. The two isomers of butylated hydroxyanisole can also be separated with good resolution. Copyright © 2017 Elsevier Ltd. All rights reserved.

Organic Semiconductors and Conductors with tert-Butyl Substituents

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Toshiki Higashino

2012-08-01

Full Text Available Tetrathiafulvalene (TTF, pentacene, and quarterthiophene with tert-butyl substituents are synthesized, and the crystal structures and the transistor properties are investigated. The tetracyanoquinodimethane (TCNQ complex of tert-butyl TTF constructs highly one-dimensional segregated columns with tetragonal crystal symmetry.

Synthesis of 4-tert-butyl-1,1-dimethylindan and 7-tert-Butyl-3,3-dimethyl-1-indanone and a comparison of isomers

International Nuclear Information System (INIS)

Eisenbraun, E.J.; Harms, W.M.; Paraniswamy, V.A.; Chen, H.H.; Porcaro, P.J.; Wood, T.F.; Chien, M.

1982-01-01

4-tert-Butyl-1,1-dimethylindan was synthesized to help establish the identity of products (5- and 6-tert-butyl-1,1-dimethylindan as minor and major products, respectively) from the sulfuric acid catalyzed condensation of tert-butylbenzene and isoprene. NMR ( 1 H and 13 C) studies of these hydrocarbons and their corresponding indanones, obtained through chromic acid oxidation, provided structural proof. Gated decoupling experiments were crucial to complete assignment

Ultrasound-assisted oxidative desulfurization of bunker-C oil using tert-butyl hydroperoxide.

Science.gov (United States)

Tang, Qiong; Lin, Song; Cheng, Ying; Liu, Sujun; Xiong, Jun-Ru

2013-09-01

This work investigated the ultrasonic assisted oxidative desulfurization of bunker-C oil with TBHP/MoO3 system. The operational parameters for the desulfurization procedure such as ultrasonic irradiation time, ultrasonic wave amplitude, catalyst initial concentration and oxidation agent initial concentration were studied. The experimental results show that the present oxidation system was very efficient for the desulfurization of bunker-C oil and ~35% sulfur was removed which was dependent on operational parameters. The application of ultrasonic irradiation allowed sulfur removal in a shorter time. The stronger the solvent polarity is, the higher the sulfur removal rate, but the recovery rate of oil is lower. The sulfur compounds in bunker-C oil reacted with TBHP to produce corresponding sulfoxide, and further oxidation produced the corresponding sulfone. Copyright © 2013 Elsevier B.V. All rights reserved.

(R-N-{2-tert-Butyl-2-[(R-tert-butylsulfonamido]ethylidene}-tert-butanesulfonamide

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Cong-Bin Fan

2008-10-01

Full Text Available The title compound, C14H30N2O2S2, is the product of the monoaddition reaction of tert-butyl magnesium chloride with bis-[(R-N-tert-butanesulfinyl]ethanediimine. There are two almost identical molecules in the asymmetric unit, the molecular conformation of which is stabilized by an intramolecular N—H...N hydrogen bond.

IRIS Toxicological Review of Tert-Butyl Alcohol (Tert-Butanol) (External Review Draft)

Science.gov (United States)

The IRIS Toxicological Review of tert-Butyl Alcohol (tert-Butanol) was released for external peer review in June 2017. EPA’s Science Advisory Board’s (SAB) Chemical Assessment Advisory Committee (CAAC) will conduct a peer review of the scientific basis supporting ...

IRIS Toxicological Review of Tert-Butyl Alcohol (Tert-Butanol) (Public Comment Draft)

Science.gov (United States)

EPA is developing an Integrated Risk Information System (IRIS) assessment of tert-butyl Alcohol (tert-butanol) and has released the public comment draft assessment for public comment and external peer review. When final, the assessment will appear on the IRIS databa...

APPLICATION OF PHOTOCATALYTIC PROCESS FOR REMOVAL OF METHYL TERT-BUTYL ETHER FROM HIGHLYCONTAMINATED WATER

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A. Mesdaghinia

2007-09-01

Full Text Available The oxygenate methyl tert-butyl ether is added to gasoline to increase the octane level and to reduce carbon monoxide and hydrocarbon emissions by vehicles. The high mobility, water solubility, and resistance to natural attenuation associated with methyl tert-butyl ether may result in contamination of ground and surface waters. In this research the degradation of aqueous methyl tert-butyl ether at relatively high concentrations was investigated by UV-vis/TiO2/H2O2 photocatalytic process. The effect of important operational parameters such as pH, amount of H2O2, catalyst loading, and irradiation time were also studied. Concentrations of methyl tert-butyl ether and intermediates such as tert-butyl formate and tert-butyl alcohol were measured over a 180 min period using a gas chromatograph equipped with flame ionization detector and combined with headspace sampler. Results showed that the time required for complete degradation increased from 30 to 180min, when the initial concentration was increased from 10 to 500mg/L. The first order rate constant for degradation of methyl tert-butyl ether from the hydroxyl radical was estimated to be 0.177 to 0.022 1/min as the concentration increased from 10 to 500mg/L. Study on the overall mineralization monitored by total organic carbon (TOC analysis showed that in the initial concentration of 100mg/L methyl tert-butyl ether, complete mineralization was obtained after 110min under UV-vis/TiO2/H2O2 photocatalytic process.

Hepatoprotective properties of kombucha tea against TBHP-induced oxidative stress via suppression of mitochondria dependent apoptosis.

Science.gov (United States)

Bhattacharya, Semantee; Gachhui, Ratan; Sil, Parames C

2011-06-01

Kombucha, a fermented tea (KT) is claimed to possess many beneficial properties. Recent studies have suggested that KT prevents paracetamol and carbon tetrachloride-induced hepatotoxicity. We investigated the beneficial role of KT was against tertiary butyl hydroperoxide (TBHP) induced cytotoxicity and cell death in murine hepatocytes. TBHP is a well known reactive oxygen species (ROS) inducer, and it induces oxidative stress in organ pathophysiology. In our experiments, TBHP caused a reduction in cell viability, enhanced the membrane leakage and disturbed the intra-cellular antioxidant machineries while simultaneous treatment of the cells with KT and this ROS inducer maintained membrane integrity and prevented the alterations in the cellular antioxidant status. These findings led us to explore the detailed molecular mechanisms involved in the protective effect of KT. TBHP introduced apoptosis as the primary phenomena of cell death as evidenced by flow cytometric analyses. In addition, ROS generation, changes in the mitochondrial membrane potential, cytochrome c release, activation of caspases (3 and 9) and Apaf-1 were detected confirming involvement of mitochondrial pathway in this pathophysiology. Simultaneous treatment of KT with TBHP, on the other hand, protected the cells against oxidative injury and maintained their normal physiology. In conclusion, KT was found to modulate the oxidative stress induced apoptosis in murine hepatocytes probably due to its antioxidant activity and functioning via mitochondria dependent pathways and could be beneficial against liver diseases, where oxidative stress is known to play a crucial role. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Biomimetic Oxidation Studies. 11. Alkane Functionalization in Aqueous Solution Utilizing in Situ Formed [Fe(2)O(eta(1)-H(2)O)(eta(1)-OAc)(TPA)(2)](3+), as an MMO Model Precatalyst, Embedded in Surface-Derivatized Silica and Contained in Micelles.

Science.gov (United States)

Neimann, Karine; Neumann, Ronny; Rabion, Alain; Buchanan, Robert M.; Fish, Richard H.

1999-07-26

The biomimetic, methane monooxygenase enzyme (MMO) precatalyst, [Fe(2)O(eta(1)-H(2)O)(eta(1)-OAc)(TPA)(2)](3+) (TPA = tris[(2-pyridyl)methyl]amine), 1, formed in situ at pH 4.2 from [Fe(2)O(&mgr;-OAc)(TPA)(2)](3+), 2, was embedded in an amorphous silicate surface modified by a combination of hydrophilic poly(ethylene oxide) and hydrophobic poly(propylene oxide). The resulting catalytic assembly was found to be a biomimetic model for the MMO active site within a hydrophobic macroenvironment, allowing alkane functionalization with tert-butyl hydroperoxide (TBHP)/O(2) in an aqueous reaction medium (pH 4.2). For example, cyclohexane was oxidized to a mixture of cyclohexanone, cyclohexanol, and cyclohexyl-tert-butyl peroxide, in a ratio of approximately 3:1:2. The balance between poly(ethylene oxide) and poly(propylene oxide), tethered on the silica surface, was crucial for maximizing the catalytic activity. The silica-based catalytic assembly showed reactivity somewhat higher in comparison to an aqueous micelle system utilizing the surfactant, cetyltrimethylammonium hydrogen sulfate at its critical micelle concentration, in which functionalization of cyclohexane with TBHP/O(2) in the presence of 1 was also studied at pH 4.2 and was found to provide similar products: cyclohexanol, cyclohexanone, and cyclohexyl-tert-butyl peroxide, in a ratio of approximately 2:3:1. Moreover, the mechanism for both the silica-based catalytic assembly and the aqueous micelle system was found to occur via the Haber-Weiss process, in which redox chemistry between 1 and TBHP provides both the t-BuO(*)() and t-BuOO(*)()( )()radicals. The t-BuO(*)()( )()radical initiates the C-H functionalization reaction to form the carbon radical, followed by O(2) trapping, to provide cyclohexyl hydroperoxide, which produces the cyclohexanol and cyclohexanone in the presence of 1, whereas the coupling product emanates from t-BuOO(*)() and cyclohexyl radicals. A discussion concerning both approaches for

Synthesis of 4-tert-Butyltoluene by Vapor Phase tert-Butylation of Toluene with tert-Butylalcohol over USY Zeolite

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Yan Ming Shen

2015-03-01

Full Text Available Vapour phase tert-butylation of toluene with tert-butylalcohol was studied over ultra-stable Y zeolite (USY catalyst. The effects of reaction temperature, toluene/TBA molar ratio and liquid space velocity on conversion of toluene and selectivity for 4-tert-butyltoluene were studied. The deactivation and regeneration of the catalyst was also investigated. The results showed that the USY zeolite catalyst offered better toluene conversion of about 30 % and 4-tert-butyltoluene selectivity of about 89 % at the suitable reaction condition as follows: reaction temperature of 120 oC, toluene/TBA ratio of 2:1 and liquid space velocity of 2 ml/g·h. The clogging of mocropores by the formed carbon or oligomers was the main reason for the deactivation of the catalyst. By combustion at 550 oC, the catalyst just lost about 5 % in toluene conversion and about 2 % in PTBT selectivity. © 2015 BCREC UNDIP. All rights reservedReceived: 17th July 2014; Revised: 31st August 2014; Accepted: 3rd September 2014How to Cite: Shen, Y.M., Yuan, S., Fan, L., Liu, D.B., Li, S.F. (2015. Synthesis of 4-tert-Butyltoluene by Vapor Phase tert-Butylation of Toluene with tert-Butylalcohol over USY Zeolite. Bulletin of Chemical Reaction Engineering & Catalysis, 10 (1: 1-7. (doi:10.9767/bcrec.10.1.7140.1-7Permalink/DOI: http://dx.doi.org/10.9767/bcrec.10.1.7140.1-7

Method for determination of methyl tert-butyl ether and its degradation products in water

Science.gov (United States)

Church, C.D.; Isabelle, L.M.; Pankow, J.F.; Rose, D.L.; Tratnyek, P.G.

1997-01-01

An analytical method is described that can detect the major alkyl ether compounds that are used as gasoline oxygenates (methyl tert-butyl ether, MTBE; ethyl tert-butyl ether, ETBE; and tert-amyl methyl ether, TAME) and their most characteristic degradation products (tert-butyl alcohol, TBA; tert-butyl formate, TBF; and tert-amyl alcohol, TAA) in water at sub-ppb concentrations. The new method involves gas chromatography (GC) with direct aqueous injection (DAI) onto a polar column via a splitless injector, coupled with detection by mass spectrometry (MS). DAI-GC/MS gives excellent agreement with conventional purge-and-trap methods for MTBE over a wide range of environmentally relevant concentrations. The new method can also give simultaneous identification of polar compounds that might occur as degradation products of gasoline oxygenates, such as TBA, TBF, TAA, methyl acetate, and acetone. When the method was applied to effluent from a column microcosm prepared with core material from an urban site in New Jersey, conversion of MTBE to TBA was observed after a lag period of 35 days. However, to date, analyses of water samples from six field sites using the DAI-GC/MS method have not produced evidence for the expected products of in situ degradation of MTBE.An analytical method is described that can detect the major alkyl ether compounds that are used as gasoline oxygenates (methyl tert-butyl ether, MTBE; ethyl tert-butyl ether, ETBE; and tert-amyl methyl ether, TAME) and their most characteristic degradation products (tert-butyl alcohol, TBA; tert-butyl formate, TBF; and tert-amyl alcohol, TAA) in water at sub-ppb concentrations. The new method involves gas chromatography (GC) with direct aqueous injection (DAI) onto a polar column via a splitless injector, coupled with detection by mass spectrometry (MS). DAI-GC/MS gives excellent agreement with conventional purge-and-trap methods for MTBE over a wide range of environmentally relevant concentrations. The new method

Thermodynamic properties of 4-tert-butyl-diphenyl oxide

International Nuclear Information System (INIS)

Druzhinina, A.I.; Pimenova, S.M.; Tarazanov, S.V.; Nesterova, T.N.; Varushchenko, R.M.

2015-01-01

Highlights: • The sample of the 4-tert-butyl-diphenyl oxide was synthesized and purified. • Heat capacities, energy of combustion, saturation vapor pressures were measured. • The temperature, the enthalpy and the entropy of fusion were determined. • The enthalpy of sublimation at T = 298.15 K was derived. • The main thermodynamic functions and functions of formation were computed. - Abstract: The main thermodynamic functions (changes of the entropy, enthalpy, and Gibbs free energy) and functions of formation at T = 298.15 K of 4-tert-butyl-diphenyl oxide in condensed and ideal gas states were computed on the basis of experimental results obtained. The heat capacities of 4-tert-butyl-diphenyl oxide was measured by vacuum adiabatic calorimetry over the temperature range (8 to 371) K. The temperature, the enthalpy and the entropy of fusion were determined. The energy of combustion of the sample was determined by static-bomb combustion calorimetry. The saturation vapor pressures of the substance were measured by dynamic transpiration method over the temperature and pressure intervals (298 to 325) K and (0.05 to 1.2) Pa. The enthalpy of sublimation at T = 298.15 K was derived. The contribution of O-(2C b ) group (where C b is the carbon atom in a benzene ring) into the absolute entropies of diphenyl oxide derivatives was assessed

and triorganotin(IV) complexes of 2-tert-butyl-4-methyl phenol

Indian Academy of Sciences (India)

TECS

-2-Me-4) have been synthesized by the reactions of di-n-butyl and dimethyltin dichlorides and tri-n-butyltin(IV) chloride with 2-tert-butyl-4-methylphenol and triethylamine in tetrahydrofuran. The reaction of triphenyltin chloride with trimethylsilyl-2-t-butyl-4- methylphenoxide in the same solvent however, gives a complex of ...

27 CFR 21.101 - tert-Butyl alcohol.

Science.gov (United States)

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false tert-Butyl alcohol. 21.101 Section 21.101 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS FORMULAS FOR DENATURED ALCOHOL AND RUM Specifications for Denaturants § 21...

Anaerobic degradation of methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA).

Science.gov (United States)

Finneran, K T; Lovley, D R

2001-05-01

The potential for anaerobic degradation of methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA) was investigated in laboratory incubations of sediments from a petroleum-contaminated aquifer and in aquatic sediments. The addition of humic substances (HS) stimulated the anaerobic degradation of MTBE in aquifer sediments in which Fe(III) was available as an electron acceptor. This is attributed to the fact that HS and other extracellular quinones can stimulate the activity of Fe(III)-reducing microorganisms by acting as an electron shuttle between Fe(III)-reducing microorganisms and insoluble Fe(III) oxides. MTBE was not degraded in aquifer sediments without Fe(III) and HS. [14C]-MTBE added to aquatic sediments adapted for anaerobic MTBE degradation was converted to 14CO2 in the presence or absence of HS or the HS analog, anthraquione-2,6-disulfonate. Unamended aquatic sediments produced 14CH4 as well as 14CO2 from [14C]-MTBE. The aquatic sediments also rapidly consumed TBA under anaerobic conditions and converted [14C]-TBA to 14CH4 and 14CO2. An adaptation period of ca. 250-300 days was required prior to the most rapid anaerobic MTBE degradation in both sediment types, whereas TBA was metabolized in the aquatic sediments without a lag. These results demonstrate that, under the appropriate conditions, MTBE and TBA can be degraded in the absence of oxygen. This suggests that it may be possible to design strategies for the anaerobic remediation of MTBE in petroleum-contaminated subsurface environments.

EFFECTS OF STIMULATOR SUBSTANCES ON AEROBIC METHYL TERT-BUTYL ETHER BIODEGRADATION BY MICROBIAL CONSORTIUM

Directory of Open Access Journals (Sweden)

M. Farrokhi ، S. Ahmadizad

2009-04-01

Full Text Available In this study dissolved humic substances and yeast extract were tested in different concentrations for enhancing methyl tert-butyl ether mineralization by isolated microorganisms from a variety of sources. All experiments were conducted at a constant temperature of 25ºC. Vials of 50 mL and 125 mL volume sealed with Teflon-lined Mini-Nert caps was used for microcosm experiments. In all experiments 1% sodium azide were used as control. Samples of bacterial cultures that metabolize methyl tert-butyl ether have been analysed by direct GC analysis using flame ionization detector. Cultures able to metabolize have been found in activated sludge and soils. These microorganisms weregram-positive bacterium. An aerobic microbial consortium was enriched in laboratory for four months. Methyl tert-butyl ether has been shown to biodegrade under aerobic and co-metabolic conditions. A microbial consortium isolated from activated sludges was identified as Cocobacillus. The concentration of the initial attached biomass was about 0.11 g/L of dry weight. The maximum mineralization rate and beneficial effects of stimulator substances on aerobic biodegradation of methyl tert-butyl ether occurred with the culture by combined concentrations of 500 mg/L of yeast extract and 20 mg/L of peat humic growth support of microbial consortium within 216 h and in presence of high oxygen levels and well mixing conditions. It was shown that adding, peat humic and yeast extract together, had better stimulatory effect on methyl tert-butyl ether biodegradation. Results clearly showed a stimulatory effect on methyl tert-butyl ether consumption higher than 20%. Consortium was capable of degrading concentrations of ≤1000 mg/L, whereas concentrations of >1000 mg/L, were not degraded.

Influence of different chemical agents (H2O2, t-BHP and MMS) on the activity of antioxidant enzymes in human HepG2 and hamster V79 cells; relationship to cytotoxicity and genotoxicity.

Science.gov (United States)

Slamenova, D; Kozics, K; Melusova, M; Horvathova, E

2015-01-01

We investigated activities of antioxidant enzymes (AEs), superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) in human HepG2 and hamster V79 cells treated with a scale of concentrations of hydrogen peroxide (H2O2), tert-butyl hydroperoxide (t-BHP) and methyl methanesulfonate (MMS). Cytotoxicity and genotoxicity of these substances were evaluated simultaneously. We have found out that H2O2, t-BHP and MMS predictably induce significant concentration-dependent increase of DNA lesions in both cell lines. Cytotoxicity detected in V79 cells with help of PE test was in a good conformity with the level of DNA damage. MTT test has proved unsuitable, except for MMS-treated V79 cells. Compared with human cells HepG2, hamster cells V79 manifested approximately similar levels of SOD and CAT but ten times higher activity of GPx. Across all concentrations tested the most significant increase of activity of the enzyme CAT was found in H2O2- and t-BHP-treated HepG2 cells, of the enzyme SOD in t-BHP- and MMS-treated V79 cells, and of the enzyme GPx in H2O2-treated V79 cells. We suggest that stimulation of enzyme activity by the relevant chemical compounds may result from transcriptional or post-transcriptional regulation of the expression of the genes CAT, SOD and GPx. Several authors suggest that moderate levels of toxic reactants can induce increase of AEs activities, while very high levels of reactants can induce their decrease, as a consequence of damage of the molecular machinery required to induce AEs. Based on a great amount of experiments, which were done and described within this paper, we can say that the above mentioned principle does not apply in general. Only the reactions of t-BHP affected HepG2 cells were consistent with this idea.

Synthesis of Highly Porous Poly(tert-butyl acrylate)-b-polysulfone-b-poly(tert-butyl acrylate) Asymmetric Membranes

KAUST Repository

Xie, Yihui; Moreno Chaparro, Nicolas; Calo, Victor M.; Cheng, Hong; Hong, Pei-Ying; Sougrat, Rachid; Behzad, Ali Reza; Tayouo Djinsu, Russell; Nunes, Suzana Pereira

2016-01-01

For the first time, self-assembly and non-solvent induced phase separation was applied to polysulfone-based linear block copolymers, reaching mechanical stability much higher than other block copolymers membranes used in this method, which were mainly based on polystyrene blocks. Poly(tert-butyl acrylate)-b-polysulfone-b-poly(tert-butyl acrylate) (PtBA30k-b-PSU14k-b-PtBA30k) with a low polydispersity of 1.4 was synthesized by combining step-growth condensation and RAFT polymerization. Various advanced electron microscopies revealed that PtBA30k-b-PSU14k-b-PtBA30k assembles into worm-like cylindrical micelles in DMAc and adopts a “flower-like” arrangement with the PSU central block forming the shell. Computational modeling described the mechanism of micelle formation and morphological transition. Asymmetric nanostructured membranes were obtained with a highly porous interconnected skin layer and a sublayer with finger-like macrovoids. Ultrafiltration tests confirmed a water permeance of 555 L m-2 h-1 bar-1 with molecular weight cut-off of 28 kg/mol. PtBA segments on the membrane surface were then hydrolyzed and complexed with metals, leading to cross-linking and enhancement of antibacterial capability.

Synthesis of Highly Porous Poly(tert-butyl acrylate)-b-polysulfone-b-poly(tert-butyl acrylate) Asymmetric Membranes

KAUST Repository

Xie, Yihui

2016-03-24

For the first time, self-assembly and non-solvent induced phase separation was applied to polysulfone-based linear block copolymers, reaching mechanical stability much higher than other block copolymers membranes used in this method, which were mainly based on polystyrene blocks. Poly(tert-butyl acrylate)-b-polysulfone-b-poly(tert-butyl acrylate) (PtBA30k-b-PSU14k-b-PtBA30k) with a low polydispersity of 1.4 was synthesized by combining step-growth condensation and RAFT polymerization. Various advanced electron microscopies revealed that PtBA30k-b-PSU14k-b-PtBA30k assembles into worm-like cylindrical micelles in DMAc and adopts a “flower-like” arrangement with the PSU central block forming the shell. Computational modeling described the mechanism of micelle formation and morphological transition. Asymmetric nanostructured membranes were obtained with a highly porous interconnected skin layer and a sublayer with finger-like macrovoids. Ultrafiltration tests confirmed a water permeance of 555 L m-2 h-1 bar-1 with molecular weight cut-off of 28 kg/mol. PtBA segments on the membrane surface were then hydrolyzed and complexed with metals, leading to cross-linking and enhancement of antibacterial capability.

Novel synthesis of manganese and vanadium mixed oxide (V2O5/OMS-2) as an efficient and selective catalyst for the oxidation of alcohols in liquid phase

International Nuclear Information System (INIS)

Mahdavi, Vahid; Soleimani, Shima

2014-01-01

Graphical abstract: Oxidation of various alcohols is studied in the liquid phase over new composite mixed oxide (V 2 O 5 /OMS-2) catalyst using tert-butyl hydroperoxide (TBHP). The activity of V 2 O 5 /OMS-2 samples was considerably increased with respect to OMS-2 catalyst and these samples are found to be suitable for the selective oxidation of alcohols. - Highlights: • V 2 O 5 /K-OMS-2 with different V/Mn molar ratios prepared by the impregnation method. • Oxidation of alcohols was studied in the liquid phase over V 2 O 5 /K-OMS-2 catalyst. • V 2 O 5 /K-OMS-2 catalyst had excellent activity for alcohol oxidation. • Benzyl alcohol oxidation using excess TBHP followed a pseudo-first order kinetic. • The selected catalyst was reused without significant loss of activity. - Abstract: This work reports the synthesis and characterization of mixed oxide vanadium–manganese V 2 O 5 /K-OMS-2 at various V/Mn molar ratios and prepared by the impregnation method. Characterization of these new composite materials was made by elemental analysis, BET, XRD, FT-IR, SEM and TEM techniques. Results of these analyses showed that vanadium impregnated samples contained mixed phases of cryptomelane and crystalline V 2 O 5 species. Oxidation of various alcohols was studied in the liquid phase over the V 2 O 5 /K-OMS-2 catalyst using tert-butyl hydroperoxide (TBHP) and H 2 O 2 as the oxidant. Activity of the V 2 O 5 /K-OMS-2 samples was increased considerably with respect to K-OMS-2 catalyst due to the interaction of manganese oxide and V 2 O 5 . The kinetic of benzyl alcohol oxidation using excess TBHP over V 2 O 5 /K-OMS-2 catalyst was investigated at different temperatures and a pseudo-first order reaction was determined with respect to benzyl alcohol. The effects of reaction time, oxidant/alcohol molar ratio, reaction temperature, solvents, catalyst recycling potential and leaching were investigated

2-tert-Butyl-5,6,7,8,9,10-hexahydrocyclohepta[b]indole

Directory of Open Access Journals (Sweden)

Janina Wobbe

2011-09-01

Full Text Available 2-tert-Butyl-5,6,7,8,9,10-hexahydrocyclohepta[b]indole was synthesized by reaction of cycloheptanone and (4-tert-butylphenylhydrazine hydrochloride in the presence of sodium acetate and sulfuric acid in glacial acetic acid via Fischer indole synthesis.

Atomic Force Microscopy Based Thermal Lithography of Poly(tert-butyl acrylate) Block Copolymer Films for Bioconjugation

NARCIS (Netherlands)

Duvigneau, Joost; Schönherr, Holger; Vancso, Gyula J.

2008-01-01

In this paper, we report on the local thermal activation of thin polymer films for area-selective surface chemical modification on micrometer and nanometer length scales. The thermally induced activation of tert-butyl ester moieties in polystyrene-block-poly(tert-butyl acrylate) (PS-b-PtBA) block

Temperature effect on tert-butyl alcohol (TBA) biodegradation kinetics in hyporheic zone soils.

Science.gov (United States)

Greenwood, Mark H; Sims, Ronald C; McLean, Joan E; Doucette, William J

2007-09-19

Remediation of tert-butyl alcohol (TBA) in subsurface waters should be taken into consideration at reformulated gasoline contaminated sites since it is a biodegradation intermediate of methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), and tert-butyl formate (TBF). The effect of temperature on TBA biodegradation has not been not been published in the literature. Biodegradation of [U 14C] TBA was determined using hyporheic zone soil microcosms. First order mineralization rate constants of TBA at 5 degrees C, 15 degrees C and 25 degrees C were 7.84 +/- 0.14 x 10-3, 9.07 +/- 0.09 x 10-3, and 15.3 +/- 0.3 x 10-3 days-1, respectively (or 2.86 +/- 0.05, 3.31 +/- 0.03, 5.60 +/- 0.14 years-1, respectively). Temperature had a statistically significant effect on the mineralization rates and was modelled using the Arrhenius equation with frequency factor (A) and activation energy (Ea) of 154 day-1 and 23,006 mol/J, respectively. Results of this study are the first to determine mineralization rates of TBA for different temperatures. The kinetic rates determined in this study can be used in groundwater fate and transport modelling of TBA at the Ronan, MT site and provide an estimate for TBA removal at other similar shallow aquifer sites and hyporheic zones as a function of seasonal change in temperature.

Estimation of the fraction of biologically active methyl tert-butyl ether degraders in a heterogeneous biomass sample

DEFF Research Database (Denmark)

Waul, Christopher Kevin; Arvin, Erik; Schmidt, Jens Ejbye

2008-01-01

The fraction of biologically active methyl tert-butyl ether degraders in reactors is just as important for prediction of removal rates as knowledge of the kinetic parameters. The fraction of biologically active methyl tert-butyl ether degraders in a heterogeneous biomass sample, taken from a packed...... bed reactor, was determined using a batch kinetic based approach. The procedure involved modeling of methyl tert-butyl ether removal rates from batch experiments followed by parameter estimations. It was estimated to be 5-14% (w/w) of the measured volatile suspended solids concentration in the reactor....

Temperature influence on mixing properties of {ethyl tert-butyl ether (ETBE) + gasoline additives}

International Nuclear Information System (INIS)

Gonzalez-Olmos, R.; Iglesias, M.

2007-01-01

The densities and ultrasonic velocity of {ethyl tert-butyl ether (ETBE) + (benzene, toluene, ethylbenzene, isooctane, tert-butyl alcohol, and ethanol)} over the temperature range (288.15 to 323.15) K and atmospheric pressure, have been measured over the whole concentration range. The experimental excess volumes and deviation of isentropic compressibilities data have been analysed in terms of different theoretical models. The gathered data improve open literature related to gasoline additives, and help to understand the ETBE volumetric and acoustic trend into different chemical environment

Temperature effect on tert-butyl alcohol (TBA biodegradation kinetics in hyporheic zone soils

Directory of Open Access Journals (Sweden)

Sims Ronald C

2007-09-01

Full Text Available Abstract Background Remediation of tert-butyl alcohol (TBA in subsurface waters should be taken into consideration at reformulated gasoline contaminated sites since it is a biodegradation intermediate of methyl tert-butyl ether (MTBE, ethyl tert-butyl ether (ETBE, and tert-butyl formate (TBF. The effect of temperature on TBA biodegradation has not been not been published in the literature. Methods Biodegradation of [U 14C] TBA was determined using hyporheic zone soil microcosms. Results First order mineralization rate constants of TBA at 5°C, 15°C and 25°C were 7.84 ± 0.14 × 10-3, 9.07 ± 0.09 × 10-3, and 15.3 ± 0.3 × 10-3 days-1, respectively (or 2.86 ± 0.05, 3.31 ± 0.03, 5.60 ± 0.14 years-1, respectively. Temperature had a statistically significant effect on the mineralization rates and was modelled using the Arrhenius equation with frequency factor (A and activation energy (Ea of 154 day-1 and 23,006 mol/J, respectively. Conclusion Results of this study are the first to determine mineralization rates of TBA for different temperatures. The kinetic rates determined in this study can be used in groundwater fate and transport modelling of TBA at the Ronan, MT site and provide an estimate for TBA removal at other similar shallow aquifer sites and hyporheic zones as a function of seasonal change in temperature.

Degradation of a recalcitrant xenobiotic compound: methyl tert-butyl ether (MTBE) metabolism by mycobacterium austroafricanum; Degradation d'un compose xenobiotique recalcitrant: metabolisme du methyl tert-butyl ether (MTBE) par mycobacterium austroafricanum IFP 2012

Energy Technology Data Exchange (ETDEWEB)

Francois, A

2002-11-01

Methyl tert-butyl ether (MTBE) is introduced up to 15% (vol/vol) in gasoline in order to obtain a good octane number and to prevent carbon monoxide emissions. However, as a consequence of storage tanks leakage, MTBE became one of the major pollutants of aquifers because of its very low biodegradability. The present study aimed at investigating the biodegradation of MTBE by Mycobacterium austroafricanum IFP 2012. The MTBE metabolic pathway was partially elucidated owing to the identification of some intermediates (tert-butyl formate (TBF), tert-butyl alcohol (TBA), a-hydroxy-isobutyric acid and acetone) and some enzymatic activities (MTBE/TBA monooxygenase (non hemic and inducible), TBF esterase, 2-propanol: NDMA oxidoreductase and another monooxygenase involved in acetone degradation). The involvement of TBF and the requirement of cobalt could be explanations for the low natural attenuation of MTBE; whereas the methoxy group does not seem to be implicated. (author)

Sorption of methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA) to synthetic resins.

Science.gov (United States)

Bi, Erping; Haderlein, Stefan B; Schmidt, Torsten C

2005-10-01

Methyl tert-butyl ether (MTBE) is a widely used gasoline oxygenate. Contamination of MTBE and its major degradation product tert-butyl alcohol (TBA) in groundwater and surface water has received great attention. However, sorption affinity and sorption mechanisms of MTBE and TBA to synthetic resins, which can be potentially used in removal of these contaminants from water, in passive sampling, or in enrichment of bacteria, have not been studied systemically. In this study, kinetic and equilibrium sorption experiments (single solute and binary mixtures) on four synthetic resins were conducted. The sorption affinity of the investigated sorbents for MTBE and TBA decreases in the order Ambersorb 563>Optipore L493>Amberlite XAD4>Amberlite XAD7, and all show higher sorption affinity for MTBE than for TBA. Binary experiments with o-xylene, a major compound of gasoline as co-contaminant, imply that all resins preferentially sorb o-xylene over MTBE or TBA, i.e., there is sorption competition. In the equilibrium aqueous concentration (Ceq) range (0.1-139.0 mg/L for MTBE, and 0.01-48.4 mg/L for TBA), experimental and modeling results as well as sorbent characteristics indicate that micropore filling and/or some other type of adsorption process (e.g., adsorption to specific sites of high sorption potential at low concentrations) rather than partitioning were the dominant sorption mechanisms. Optipore L493 has favourable sorption and desorption characteristics, and is a suitable sorbent, e.g., in bacteria enrichment or passive sampling for moderately polar compounds. However, for highly polar compounds such as TBA, Ambersorb 563 might be a better choice, especially in water treatment.

Polyvinylpolypyrrolidone-Supported Boron Trifluoride; Highly Efficient Catalyst for the Synthesis of N-tert-Butyl Amides

Directory of Open Access Journals (Sweden)

Masoud Mokhtary

2012-01-01

Full Text Available Highly efficient method for the preparation of N-tert-butyl amides by reaction of nitriles with tert-butyl acetate is described using polyvinylpolypyrrolidone-supported boron trifluoride (PVPP-BF3 at 70°C in good to excellent yields. Selective amidation of benzonitrile in the presence of acetonitrile was also achieved. polyvinylpolypyrrolidone-boron trifluoride complex shows non-corrosive and stable solid catalyst elevated Lewis acid property.

Isolation of major phenolics from Launaea spinosa and their protective effect on HepG2 cells damaged with t-BHP.

Science.gov (United States)

Abdallah, Hossam; Farag, Mohamed; Osman, Samir; Kim, Da hye; Kang, Kyungsu; Pan, Cheol-Ho; Abdel-Sattar, Essam

2016-01-01

Some Launaea species (Asteraceae) are used traditionally to treat liver oxidative stress. The present study investigates the protective effects of isolated compounds from Launaea spinosa Sch. Bip. (Asteraceae) against oxidative stress on t-BHP-induced HepG2 cells. Major phenolic content from flowering aerial parts of L. spinosa was isolated and identified. The protective effects of isolated compounds (10 and 20 μM) against oxidative stress induced by tert-butyl hydroperoxide (t-BHP) in HepG2 cells were investigated through the measurement of aspartate aminotransferase (AST), alanine transaminase (ALT), and superoxide dismutase (SOD) levels. A new phenolic compound identified as 2,3-diferulyl R,R-(+) methyl tartrate (6), in addition to five known metabolites, esculetin (1), esculetin-7-O-d-glucoside (cichoriin) (2), fertaric acid (3), acacetin-7-O-d-glucoside (4), and acacetin-7-O-d-glucuronic acid (5), were isolated. Oxidant-induced damage by 200 μM t-BHP in HepG2 cells was inhibited by compounds 1, 4, and 5 (10 and 20 μM), or quercetin (10 μM; positive control). The protective effects of compounds 1, 4, and 5 were associated with decreasing in AST, ALT, and SOD levels. Compound 4 (20 μM) decreased the AST level from 128.5 ± 13.9 to 7.9 ±1.8 U/mL. Meanwhile, compound 1 (20 μM) decreased ALT activity from 20.3 ± 7.0 to 7.6 ± 2.4 U/mL, while compound 5 decreased SOD levels from 41.6 ± 9.0 to 28.3 ± 3.4 mU/mg. The major phenolic compounds isolated from L. spinosa displayed a significant cytoprotective effect against oxidative stress, leading to maintenance of the normal redox status of the cell.

Synthesis and characterization of new magnetically recoverable molybdenum nanocatalyst for epoxidation of olefins

Energy Technology Data Exchange (ETDEWEB)

Masteri-Farahani, M., E-mail: mfarahany@yahoo.com [Faculty of Chemistry, University of Tarbiat Moallem, Tehran (Iran, Islamic Republic of); Kashef, Z. [Faculty of Chemistry, University of Tarbiat Moallem, Tehran (Iran, Islamic Republic of)

2012-04-15

New heterogeneous molybdenum catalyst was prepared through covalent attachment of a Schiff base ligand on the surface of silica coated magnetite nanoparticles via aminopropyl spacer and subsequent complexation with MoO{sub 2}(acac){sub 2}. The prepared nanocatalyst was characterized with Fourier transform infrared spectroscopy, X-ray diffraction, scanning and transmission electron microscopies and vibrating sample magnetometry. Catalytic epoxidation of some olefins and allylic alcohols by prepared nanocatalyst using tert-butyl hydroperoxide and cumene hydroperoxide as oxidants was achieved with good activities and selectivities. - Highlights: Black-Right-Pointing-Pointer Silica coated magnetite nanoparticles were modified with a Schiff base ligand. Black-Right-Pointing-Pointer Next reaction with MoO{sub 2}(acac){sub 2} afforded magnetically recoverable nanocatalyst. Black-Right-Pointing-Pointer The prepared nanocatalyst catalyzed the epoxidation of olefins with TBHP.

Degradation of a recalcitrant xenobiotic compound: methyl tert-butyl ether (MTBE) metabolism by mycobacterium austroafricanum; Degradation d'un compose xenobiotique recalcitrant: metabolisme du methyl tert-butyl ether (MTBE) par mycobacterium austroafricanum IFP 2012

Energy Technology Data Exchange (ETDEWEB)

Francois, A.

2002-11-01

Methyl tert-butyl ether (MTBE) is introduced up to 15% (vol/vol) in gasoline in order to obtain a good octane number and to prevent carbon monoxide emissions. However, as a consequence of storage tanks leakage, MTBE became one of the major pollutants of aquifers because of its very low biodegradability. The present study aimed at investigating the biodegradation of MTBE by Mycobacterium austroafricanum IFP 2012. The MTBE metabolic pathway was partially elucidated owing to the identification of some intermediates (tert-butyl formate (TBF), tert-butyl alcohol (TBA), a-hydroxy-isobutyric acid and acetone) and some enzymatic activities (MTBE/TBA monooxygenase (non hemic and inducible), TBF esterase, 2-propanol: NDMA oxidoreductase and another monooxygenase involved in acetone degradation). The involvement of TBF and the requirement of cobalt could be explanations for the low natural attenuation of MTBE; whereas the methoxy group does not seem to be implicated. (author)

Hydrophobic hydration and anomalous excess partial molar volume of tert-butyl alcohol-water mixture studied by quasielastic neutron scattering

International Nuclear Information System (INIS)

Nakada, Masaru; Maruyama, Kenji; Misawa, Masakatsu; Yamamuro, Osamu

2007-01-01

Quasielastic neutron scattering has been used to investigate the hydration of alcohol clusters in tert-butyl alcohol-water mixture. The measurements were made in a range of alcohol concentration, x TBA , from 0.0 to 0.17 in mole fraction at 25degC. Fraction, α, of water molecules hydrated to fractal-surface of alcohol clusters in tert-butyl alcohol-water mixture was obtained as a function of alcohol concentration. Average hydration number N WS of tert-butyl alcohol molecule was derived from the value of α as a function of alcohol concentration. The value of N WS for an isolated alcohol molecule in water was 19-21. The anomalous excess partial molar volume of tert-butyl alcohol-water mixture was interpreted successfully by applying the same model with the same values of volume parameter as used for 1-propanol-water mixture, δ 1 (=-0.36 cm 3 ·mol -1 ) and δ 2 (=0.60 cm 3 ·mol -1 ). (author)

On the interaction of molybdenum cyanide complexes with hydroperoxide of tertiary butyl

International Nuclear Information System (INIS)

Vretsena, N.B.; Nikipanchuk, M.V.; Chernyak, B.I.

1979-01-01

Conducted is investigation of interaction of potassium dioxotetracyanomolybdate (4) K 4 [MoO 2 (CN) 4 ], potassium oxotetracyanomolybdate (2) K 4 [MoO(CN) 4 ] and potassium tetracyanomolybdate K 4 [Mo(CN) 4 ] in CCl 4 and hydroperoxide of tertiary butyl medium, (HPTB). Shown is the process complex mechanism which leads to molybdenum oxidation in complexes and also to coordination and HPTB decomposition. Calculated are parameters of complex formation process of molybdenum with HPTB cyanide complexes

Standard thermochemical characteristics of combustion and formation of 3,5-di-tert-butyl-o-benzoquinone and 3,6-di-tert-butyl-o-benzoquinone at T = 298.15 K

International Nuclear Information System (INIS)

Pashanova, Kira I.; Abakumov, Gleb A.; Markin, Alexey V.; Piskunov, Alexander V.; Smirnova, Natalia N.

2016-01-01

Highlights: • We report the results of thermochemical study for benzoquinone derivatives. • Optimal conditions for determination of combustion energy for benzoquinone were done. • The formation enthalpies for crystalline benzoquinone have been detected at T = 298.15 K. • The formation enthalpy of isomeric quinones were compared. - Abstract: Optimal conditions for investigations of thermodynamic properties have been determined experimentally by the method of combustion calorimetry for compounds of the o-benzoquinone series. In the present work, the energies of combustion in oxygen were measured at T = 298.15 K by static bomb combustion calorimetry for 3,5-di-tert-butyl-o-benzoquinone and 3,6-di-tert-butyl-o-benzoquinone. The experimental values have been used to calculate the standard (p° = 0.1 MPa) molar enthalpy of combustion Δ_cH"o_m and formation Δ_fH"o_m for the examined compounds in the crystalline phase.

The oxidation of limonene at raised pressure and over the various titanium-silicate catalysts

Directory of Open Access Journals (Sweden)

Wróblewska Agnieszka

2015-12-01

Full Text Available This work presents the studies on the oxidation of limonene with hydrogen peroxide and tert-butyl hydroperoxide (TBHP in the presence of : TS-2, Ti-Beta, Ti-MCM-41 and Ti-MWW catalysts, at the autogenic pressure and atmospheric pressure. The examination were performed at the following conditions: the temperature of 140°C (studies in the autoclave and 80°C (studies in glass reactor, the molar ratio of limonene/oxidant (H2O2 or WNTB = 1:1, the methanol concentration 80 wt%, the catalyst content 3 wt%, the reaction time 3 h and the intensity of stirring 500 rpm. The analysis of the results showed that in process not only 1,2-epoxylimonene was formed but also: 1,2-epoxylimonene diol, carveol, carvone and perillyl alcohol but for 1,2-epoxylimonene obtaining the better method was the method at the autogenic pressure and in the presence of TBHP.

Linear free energy relationships in heterogeneous catalysis--13. The dehydration of aliphatic alcohols over silica-alumina. [N-butyl alcohol, sec. -butyl or isopropyl alcohol, tert. -butyl alcolol

Energy Technology Data Exchange (ETDEWEB)

Take, J; Matsumoto, T; Yoneda, Y

1978-01-01

The dehydration of n-butyl alcohol at 120/sup 0/-166/sup 0/C, sec.-butyl or isopropyl alcohol at 100/sup 0/-145/sup 0/C, and tert.-butyl alcohol at 54/sup 0/-80/sup 0/C, over silica/alumina catalyst was zero order in alcohol at 0.01-0.1 atm, and the activation energies were 35.3, 31.7, 32.0, and 29.9 kcal/mol, respectively. The zero-order rate constants were mainly affected by the activation energies since the preexponential factors varied little except for tert.-butyl alcohol. A linear relationship was found between the activation energy or the logarithm of the zero-order rate constant and the heterolytic bond dissociation energy for the carbon-oxygen bond in alcohols D(R/sup +/OH/sup -/). The activation energy increased and the rate constant decreased with increasing D(R/sup +/OH/sup -/). The results indicate that dehydration is E1 over this catalyst, but a similar correlation was observed based on published data for dehydration over alumina, which follows an E2 mechanism, indicating that heterolytic cleavage of the C-O bond is rate-determining in both mechanisms.

Actinide-carbon bonds: insertion reactions of carbon monoxide, tert-butyl isocyanide, and tert-butyl cyanide into [(Me3Si)2N]2MCH2Si(Me)2NSiMe3

International Nuclear Information System (INIS)

Simpson, S.J.; Andersen, R.A.

1981-01-01

The thorium or uranium metallacycles [(Me 2 Si) 2 N] 2 MCH 2 Si(Me) 2 NSiMe 3 (I) react with tert-butyl cyanide to give the six-membered ring compounds [(Me 3 Si) 2 N] 2 MN = C(t-Bu)CH 2 Si(Me) 2 NSiMe 3 . The metallacycles (I) also react with the isoelectronic molecules tert-butyl isocyanide and carbon monoxide to give the unique five-membered ring compounds with exocyclic carbon-carbon double bonds, [(Me 3 Si) 2 N] 2 MXC(=CH 2 )Si(Me) 2 NSiMe 3 , where X is t-BuN or oxygen. The four-membered ring metallacycles (I) give simple coordination complexes of the type [(Me 3 Si) 2 N] 2 MCH 2 Si-(Me) 2 NSiMe 3 (N 3 SiMe 3 ) with trimethylsilyl azide

Synthesis, characterization and application of a nano-manganese-catalyst as an efficient solid catalyst for solvent free selective oxidation of ethylbenzene, cyclohexene, and benzylalcohol

Science.gov (United States)

Habibi, Davood; Faraji, Ali Reza

2013-07-01

The object of this study is to synthesize the heterogeneous Mn-nano-catalyst (MNC) which has been covalently anchored on a modified nanoscaleSiO2/Al2O3, and characterized by FT-IR, UV-Vis, CHN elemental analysis, EDS, TEM, and EDX. The method is efficient for the highly selective oxidation of ethylbenzene, cyclohexene, and benzylalcohol without the need to any solvents, using tert-butyl hydroperoxide (TBHP) as an oxidant. Oxidation of ethylbenzene, cyclohexene, and benzylalcohol gave acetophenone, 2-cyclohexene-1-one and benzaldehyde, respectively, as major products. Reaction conditions have been optimized by considering the effect of various factors such as reaction time, amounts of substrates and oxidant, Mn-nano-catalyst and application of various solvents.

Inhibition of Palmityl Carnitine Oxidation in Rat Liver Mitochondria by Tert-Butyl Hydroperoxide

Czech Academy of Sciences Publication Activity Database

Červinková, Z.; Rauchová, Hana; Křiváková, P.; Drahota, Zdeněk

2008-01-01

Roč. 57, č. 1 (2008), s. 133-136 ISSN 0862-8408 R&D Projects: GA ČR(CZ) GD303/03/H065; GA ČR(CZ) GA305/04/0500; GA MŠk(CZ) 1M0520 Institutional research plan: CEZ:AV0Z50110509 Keywords : liver mitochondria * palmityl carnitine oxidation * tert-butylhydroperoxide Subject RIV: ED - Physiology Impact factor: 1.653, year: 2008

{2,6-Bis[(di-tert-butyl-phosphino)-methyl]-phenyl}chloridonickel(II).

Science.gov (United States)

Boro, Brian J; Dickie, Diane A; Goldberg, Karen I; Kemp, Richard A

2008-09-20

In the title compound, [Ni(C(24)H(43)P(2))Cl], the Ni atom adopts a distorted square-planar geometry, with the P atoms of the 2,6-bis-[(di-tert-butyl-phosphino)meth-yl]phenyl ligand trans to one another. The P-Ni-P plane is twisted out of the plane of the aromatic ring by 21.97 (6)°.

5,11,17,23-Tetra-tert-butyl-25,26,27,28-tetrapropynyloxy-2,8,14,20-tetrathiacalix[4]arene

Directory of Open Access Journals (Sweden)

Xiang-Gao Meng

2009-12-01

Full Text Available The title compound [systematic name: 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetrapropynyloxy-2,8,14,20-tetrathiacalix[4]arene], C52H56O4S4, is an alkylated product bearing four propyne groups at the lower rim of a 5,11,17,23-tetra-tert-butyl-tetrathiacalix[4]arene. The molecule is located on a crystallographic twofold rotation axis, running through two S atoms and perpendicular to the long axis of the molecule. The four propyne groups, located in an alternate fashion above and below the mean plane of the four S atoms, are almost parallel to the calixarene long axis. The dihedral angle between the two crystallographically independent benzene rings is 86.77 (14°. Two tert-butyl groups are disordered over two positions with site occupancies of 0.59 (2 and 0.41 (2.

Effect of tert-Butyl Functionalization on the Photoexcited Decay of a Fe(II)-N-Heterocyclic Carbene Complex

DEFF Research Database (Denmark)

Pápai, Mátyás Imre; Penfold, Thomas J.; Møller, Klaus Braagaard

2016-01-01

-vibronic quantum dynamics simulations on the Fe-N-heterocyclic carbene complex, [Fe(btbip)2]2+ (btbip = 2,6-bis(3-tert-butyl-imidazole-1-ylidene)pyridine). The results demonstrate that a relatively minor structural change compared to its parent complex, [Fe(bmip)2]2+ (bmip = 2,6-bis(3-methyl-imidazole-1-ylidene....... This occurs because the tert-butyl functionalization stabilizes the 1MC states, enabling the 1,3MLCT → 1MC population transfer to occur close to the Franck-Condon geometry, making the conversion very efficient. Subsequently, a spin cascade occurs within the MC manifold, leading to the population of triplet...

Contact allergy to 2-hydroxy-5-tert-butyl benzylalcohol and 2,6-bis(hydroxymethyl)-4-tert-butylphenol, components of a phenolic resin used in marking pens

DEFF Research Database (Denmark)

Hagdrup, H; Egsgaard, H; Carlsen, L

1994-01-01

2-hydroxy-5-tert-butyl benzylalcohol and 2,6-bis(hydroxymethyl)-4-tert-butylphenol were identified as contact allergens in a phenolic resin used as a tackifier in the ink of a marking pen, which, after being used directly on the skin, caused an acute contact dermatitis on the hand of a 13-year...

Protective Effect of Theaflavin on Erythrocytes Subjected to In Vitro Oxidative Stress

Directory of Open Access Journals (Sweden)

Mahejabeen Fatima

2013-01-01

Full Text Available Antioxidant and free radical scavenging effect of black tea theaflavins has been shown in many epidemiological studies. In the present work we report the protective mechanism of tea theaflavins on biomarkers of oxidative stress, which are elevated during stress conditions. We hereby report the in vitro effect of theaflavins on erythrocyte malondialdehyde (MDA, intracellular reduced glutathione (GSH, and plasma membrane redox system (PMRS of rats. The effect of theaflavin on PMRS has also been validated through an in silico docking simulation study using Molegro Virtual Docker (MVD. We report that theaflavins show significant protection to erythrocyte against oxidative stress induced by tert-butyl hydroperoxide (t-BHP. The findings suggest a possible protective role of theaflavins as antioxidant.

Metabolism of the fungicide Denmert (S-n-butyl S'-p-tert-butyl-benzyl N-3-pyridyldithiocarbonimidate, S-1358) and Denmert sulfoxides in liver enzyme systems

International Nuclear Information System (INIS)

Ohkawa, Hideo; Okihara, Yukiko; Miyamoto, Junshi

1976-01-01

On incubation with rat liver microsomes plus MADPH, Denmert (S-n-butyl S'-p-tert-butylbenzyl N-3-pyridyldithiocarbonimidate) underwent at least two different types of oxidation; hydroxylation and sulfoxidation. Hydroxylation of Denmert at the tert-butyl group was one of the major metabolic attacks in mammalian metabolism. Sulfoxidation of Denmert gave two isomers of Denmert sulfoxides which were intermediates in the metabolism and readily transformed into 2-(3'-pyridylimino)-4-carboxylthiazolidine (HM) in the presence of L-cysteine without enzymatic mediation. This type of conjugation with cysteine appears to be a new class of metabolic reactions in mammals. Denmert S-oxide showed increased fungicidal activity when assayed in liquid cultures, but not on plant leaves. (auth.)

A new efficient synthesis of isothiocyanates from amines using di-tert-butyl dicarbonate

DEFF Research Database (Denmark)

Munch, Henrik; Hansen, Jon S.; Pittelkow, Michael

2008-01-01

Alkyl and aryl amines are converted smoothly to the corresponding isothiocyanates via the dithiocarbamates in good to excellent yields using di-tert-butyl dicarbonate (Boc(2)O) and 1-3 mol% of DMAP or DABCO as catalyst. As most of the byproducts are volatile, the work-up involves simple evaporation...

n-Alkane assimilation and tert-butyl alcohol (TBA) oxidation capacity in Mycobacterium austroafricanum strains.

Science.gov (United States)

Lopes Ferreira, Nicolas; Mathis, Hugues; Labbé, Diane; Monot, Frédéric; Greer, Charles W; Fayolle-Guichard, Françoise

2007-06-01

Mycobacterium austroafricanum IFP 2012, which grows on methyl tert-butyl ether (MTBE) and on tert-butyl alcohol (TBA), the main intermediate of MTBE degradation, also grows on a broad range of n-alkanes (C2 to C16). A single alkB gene copy, encoding a non-heme alkane monooxygenase, was partially amplified from the genome of this bacterium. Its expression was induced after growth on n-propane, n-hexane, n-hexadecane and on TBA but not after growth on LB. The capacity of other fast-growing mycobacteria to grow on n-alkanes (C1 to C16) and to degrade TBA after growth on n-alkanes was compared to that of M. austroafricanum IFP 2012. We studied M. austroafricanum IFP 2012 and IFP 2015 able to grow on MTBE, M. austroafricanum IFP 2173 able to grow on isooctane, Mycobacterium sp. IFP 2009 able to grow on ethyl tert-butyl ether (ETBE), M. vaccae JOB5 (M. austroaafricanum ATCC 29678) able to degrade MTBE and TBA and M. smegmatis mc2 155 with no known degradation capacity towards fuel oxygenates. The M. austroafricanum strains grew on a broad range of n-alkanes and three were able to degrade TBA after growth on propane, hexane and hexadecane. An alkB gene was partially amplified from the genome of all mycobacteria and a sequence comparison demonstrated a close relationship among the M. austroafricanum strains. This is the first report suggesting the involvement of an alkane hydroxylase in TBA oxidation, a key step during MTBE metabolism.

Black rice extract protected HepG2 cells from oxidative stress-induced cell death via ERK1/2 and Akt activation

Science.gov (United States)

Yoon, Jaemin; Ham, Hyeonmi; Sung, Jeehye; Kim, Younghwa; Choi, Youngmin; Lee, Jeom-Sig; Jeong, Heon-Sang; Lee, Junsoo

2014-01-01

BACKGROUND/OBJECTIVES The objective of this study was to evaluate the protective effect of black rice extract (BRE) on tert-butyl hydroperoxide (TBHP)-induced oxidative injury in HepG2 cells. MATERIALS/METHODS Methanolic extract from black rice was evaluated for the protective effect on TBHP-induced oxidative injury in HepG2 cells. Several biomarkers that modulate cell survival and death including reactive oxygen species (ROS), caspase-3 activity, and related cellular kinases were determined. RESULTS TBHP induced cell death and apoptosis by a rapid increase in ROS generation and caspase-3 activity. Moreover, TBHP-induced oxidative stress resulted in a transient ERK1/2 activation and a sustained increase of JNK1/2 activation. While, BRE pretreatment protects the cells against oxidative stress by reducing cell death, caspase-3 activity, and ROS generation and also by preventing ERKs deactivation and the prolonged JNKs activation. Moreover, pretreatment of BRE increased the activation of ERKs and Akt which are pro-survival signal proteins. However, this effect was blunted in the presence of ERKs and Akt inhibitors. CONCLUSIONS These results suggest that activation of ERKs and Akt pathway might be involved in the cytoprotective effect of BRE against oxidative stress. Our findings provide new insights into the cytoprotective effects and its possible mechanism of black rice against oxidative stress. PMID:24741394

Isothermal (vapor + liquid) equilibria and excess enthalpy data of {1-hexene + methyl butyl ether (MBE)} and {1-hexene + methyl tert-butyl ether (MTBE)} binary systems at several temperatures

International Nuclear Information System (INIS)

Hani, Rachida; Solimando, Roland; Negadi, Latifa; Jose, Jacques; Ait Kaci, Ahmed

2012-01-01

Highlights: ► Vapor pressures of (1-hexene + methyl butyl ether) or (1-hexene + methyl tert-butyl ether) are reported between (263 and 363) K. ► The two mixtures exhibit positive G E . ► Additionally, molar excess enthalpies, H E , for the two binary systems have been measured at 303.15. - Abstract: The vapor pressures of {1-hexene + methyl butyl ether (MBE)} and {1-hexene + methyl tert-butyl ether (MTBE)} binary mixtures and of the three pure components were measured by means of a static device at temperatures between (263 and 333) K. The data were correlated with the Antoine equation. From these data, excess Gibbs functions were calculated for several constant temperatures and fitted to a third-order Redlich–Kister equation using the Barker’s method. Additionally, molar excess enthalpies, H E , for the two binary systems have been measured at 303.15 K using an isothermal flow calorimeter.

Di-tert-butyl-chlorido(N,N-dibenzyl-dithio-carbamato)tin(IV).

Science.gov (United States)

Abdul Muthalib, Amirah Faizah; Baba, Ibrahim; Mohamed Tahir, Mohamed Ibrahim; Tiekink, Edward R T

2011-02-26

The Sn(IV) atom in the title diorganotin dithio-carbamate, [Sn(C(4)H(9))(2)(C(15)H(14)NS(2))Cl], is penta-coordinated by an asymmetrically coordinating dithio-carbamate ligand, a Cl atom and two C atoms of the Sn-bound tert-butyl groups. The resulting C(2)ClS(2) donor set defines a coordination geometry inter-mediate between square pyramidal and trigonal bipyramidal with a slight tendency towards the former.

N-tert-Butyl-3-hydroxy-5-androstene-17-carboxamide monohydrate

Directory of Open Access Journals (Sweden)

Jiang-Sheng Li

2009-07-01

Full Text Available In the title compound, C24H39NO2·H2O, the A and C rings of the pregnolene derivative sterol adopt chair conformations, with the B ring in a flattened chair conformation and the five-membered ring in an envelope conformation twisted about the C/D ring junction. The N-tert-butylcarboxamide substituent is equatorial. The 3β-hydroxy H atom and one H atom of the water molecule are disordered over two positions with equal occupancies. In the crystal structure, O—H...O hydrogen bonds between the 3β-hydroxy groups of neighbouring molecules form dimers in the bc plane and these dimers are stacked along the a axis by additional O—H...O hydrogen bonds involving the water molecules. The steric effect of the bulky tert-butyl substituent in the carboxamide chain precludes hydrogen-bond formation by the N—H group.

Crystal structure of 2-tert-butyl-1,3-thiazolo[4,5-b]pyridine

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Gamal A. El-Hiti

2014-09-01

Full Text Available The title compound, C10H12N2S, does not contain any strong hydrogen-bond donors but two long C—H...N contacts are observed in the crystal structure, with the most linear interaction linking molecules along [010]. The ellipsoids of the tert-butyl group indicate large librational motion.

Use of experimental design for the purge-and-trap-gas chromatography-mass spectrometry determination of methyl tert.-butyl ether, tert.-butyl alcohol and BTEX in groundwater at trace level.

Science.gov (United States)

Bianchi, F; Careri, M; Marengo, E; Musci, M

2002-10-25

An efficient method for the simultaneous determination of methyl tert.-butyl ether, tert.-butyl alcohol, benzene, toluene, ethylbenzene and xylene isomers in groundwater by purge-and-trap-gas chromatography-mass spectrometry was developed and validated. Experimental design was used to investigate the effects of temperature of extraction, time of extraction and percentage of salt added to the water samples. Regression models and desirability functions were applied to find the experimental conditions providing the highest global extraction yield. Validation was carried out in terms of limits of detection (LOD), limits of quantitation (LOQ), linearity and precision. LOD values ranging from 2.6 to 23 ng l(-1) were achieved, whereas linearity was statistically verified over two orders of magnitude for each compound. Precision was evaluated testing two concentration levels. Good results were obtained both in terms of intra-day repeatability and intermediate precision: RSD% lower than 4.5% at the highest concentration and lower than 13% at the lowest one were calculated for intra-day repeatability. A groundwater sample suspected of contamination by leaking underground petroleum storage tanks was analysed and some of the analytes were detected and quantitated.

Di-tert-butyl 2,2′-[(biphenyl-4,4′-diyldioxy]diacetate

Directory of Open Access Journals (Sweden)

Qamar Ali

2010-07-01

Full Text Available The complete molecule of the title compound, C24H30O6, is generated by a crystallographic inversion centre. In the unique part of the molecule, the four-atom –O–CH2–C(= O–O– chain between the benzene ring and the tert-butyl group assumes a zigzag conformation [O—C—C—O torsion angle = −162.3 (1°].

Synthesis of nanostructured NiO/Co3O4 through thermal decomposition of a bimetallic (Ni/Co) metal-organic framework as catalyst for cyclooctene epoxidation

Science.gov (United States)

Abbasi, Alireza; Soleimani, Mohammad; Najafi, Mahnaz; Geranmayeh, Shokoofeh

2017-04-01

Hydrothermal approach has led to the formation of a three-dimensional metal-organic framework (MOF), [NiCo(μ2-tp)(μ4-tp)(4,4‧-bpy)2]n (1) (tp = terephthalic acid and 4,4‧-bpy = 4,4‧-bipyridine) which was characterized by means of single-crystal X-ray diffraction analysis, powder X-ray diffraction (PXRD), FT-IR spectroscopy, scanning electron microscopy (SEM) and inductive coupled plasma optical emission spectroscopy (ICP-OES). Thermal decomposition of the MOF afforded nanostructured mixed metal oxide, namely NiO/Co3O4. The XRD and SEM analysis confirm the formation of the mixed metal oxide. The nanostructured NiO/Co3O4 demonstrated good catalytic activity and selectivity in the epoxidation of cyclooctene in the presence of tert-butyl hydroperoxide (TBHP) as oxidant.

An octanuclear molybdenum(VI) complex containing coordinatively bound 4,4'-di-tert-butyl-2,2'-bipyridine, [Mo8O22(OH)4(di-tBu-bipy)4]: synthesis, structure, and catalytic epoxidation of bio-derived olefins.

Science.gov (United States)

Amarante, Tatiana R; Neves, Patrícia; Tomé, Cátia; Abrantes, Marta; Valente, Anabela A; Paz, Filipe A Almeida; Pillinger, Martyn; Gonçalves, Isabel S

2012-03-19

The reaction of [MoO(2)Cl(2)(di-tBu-bipy)] (1) (di-tBu-bipy = 4,4'-di-tert-butyl-2,2'-bipyridine) with water at 100-120 °C in a Teflon-lined stainless steel autoclave, in an open reflux system, or in a microwave synthesis system gave the octanuclear complex [Mo(8)O(22)(OH)(4)(di-tBu-bipy)(4)] (2) as a microcrystalline powder in good yields. Single crystals of 2 suitable for X-ray diffraction were obtained by the reaction of MoO(3) and di-tBu-bipy in water at 160 °C for 3 days. The molecular structure of 2 comprises a purely inorganic core, Mo(4)O(8)(μ(3)-OH)(2)(μ(2)-O)(2), attached to two peripheral oxo-bridged binuclear units, Mo(2)O(4)(μ(2)-O)(2)(OH)(di-tBu-bipy)(2). The inorganic core is composed of a unique assembly of four {MoO(5)} distorted square pyramids connected to each other via edge-sharing. Overall, the octanuclear complex adopts a highly distorted form strongly resembling an "S"-shaped molecular unit. Complex 2 was applied in the catalytic epoxidation of the biorenewable olefins DL-limonene (Lim) and methyl oleate (Ole), using tert-butylhydroperoxide (TBHP) as an oxygen donor, under mild reaction conditions (55 °C, air). The reactions of Lim and Ole gave the respective epoxide monomers in fairly high selectivities at high conversions (89% 1,2-epoxy-p-menth-8-ene selectivity at 96% Lim conversion; 99% methyl 9,10-epoxystearate selectivity at 94% Ole conversion, reached within 24 h reaction). Iodometric titrations revealed no measurable "non-productive" decomposition of TBHP. © 2012 American Chemical Society

INHALATION EXPOSURE TO METHYL TERT-BUTYL ETHER (MTBE) AND DIBROMOCHLOROMETHANE (DBCM) USING CONTINUOUS BREATH ANALYSIS

Science.gov (United States)

The oxygenate methyl tert-butyl ether (MTBE) has been added to gasoline to help meet national ambient air quality standards in those parts of the U.S. that are non-compliant for carbon monoxide. Although MTBE has provided important health benefits in terms of reduced haza...

Formation of Germa-ketenimine on the Ge(100) Surface by Adsorption of tert-Butyl Isocyanide.

Science.gov (United States)

Shong, Bonggeun; Yoo, Jong Suk; Sandoval, Tania E; Bent, Stacey F

2017-06-28

Reactions of the (100) surfaces of Ge and Si with organic molecules have been generally understood within the concept of "dimers" formed by the 2 × 1 surface reconstruction. In this work, the adsorption of tert-butyl isocyanide on the Ge(100)-2 × 1 surface at large exposures is investigated under ultrahigh vacuum conditions. A combination of infrared spectroscopy, X-ray photoelectron spectroscopy, and temperature-programmed desorption experiments along with dispersion-corrected density functional theory calculations is used to determine the surface products. Upon adsorption of a dense monolayer of tert-butyl isocyanide, a product whose structure resembles a germa-ketenimine (N=C=Ge) with σ donation toward and π back-donation from the Ge(100) surface appears. Formation of this structure involves divalent-type surface Ge atoms that arise from cleavage of the Ge(100)-2 × 1 surface dimers. Our results reveal an unprecedented class of reactions of organic molecules at the Ge(100) surface.

Nanosized ruthenium particles decorated carbon nanofibers as active catalysts for the oxidation of p-cymene by molecular oxygen

CSIR Research Space (South Africa)

Makgwane, PR

2013-07-01

Full Text Available demonstrated that the direct participation of the catalyst in p-cymene C-H bond activation occurred via catalytic decomposition of tertiary-butyl hydroperoxide (TBHP), which was added as an initiator, into a free-radical chain initiator rather than the direct H...

Sulfuric acid functional zirconium (or aluminum) incorporated mesoporous MCM-48 solid acid catalysts for alkylation of phenol with tert-butyl alcohol

International Nuclear Information System (INIS)

Jiang, Tingshun; Cheng, Jinlian; Liu, Wangping; Fu, Lie; Zhou, Xuping; Zhao, Qian; Yin, Hengbo

2014-01-01

Several zirconium (or aluminum) incorporated mesoporous MCM-48 solid acid catalysts (SO 4 2− /Zr-MCM-48 and SO 4 2− /Al-MCM-48) were prepared by the impregnation method and their physicochemical properties were characterized by means of XRD, FT-IR, TEM, NH 3 -TPD and N 2 physical adsorption. Also, the catalytic activities of these solid acid catalysts were evaluated by the alkylation of phenol with tert-butyl alcohol. The effect of weight hour space velocity (WHSV), reaction time and reaction temperature on catalytic properties was also studied. The results show that the SO 4 2− /Zr-MCM-48 and SO 4 2− /Al-MCM-48 still have good mesoporous structure and long range ordering. Compared with the Zr (or Al)–MCM-48 samples, SO 4 2− /Zr-MCM-48 and SO 4 2− /Al-MCM-48 solid acid catalysts have strong acidity and exhibit high activities in alkylation reaction of phenol with tert-butyl alcohol. The SO 4 2− /Zr-MCM-48-25 (molar ratio of Si/Zr=0.04) catalyst was found to be the most promising and gave the highest phenol conversion among all catalysts. A maximum phenol conversion of 91.6% with 4-tert-butyl phenol (4-TBP) selectivity of 81.8% was achieved when the molar ratio of tert-butyl alcohol:phenol is 2:1, reaction time is 2 h, the WHSV is 2 h −1 and the reaction temperature is 140 °C. - Highlights: • Sulfuric acid functional mesoporous solid acid catalysts were prepared via impregnation method. • The alkylation of phenol with tert-butyl alcohol was carried out over these solid acid catalysts. • The catalytic activity of SO 4 2− /Zr-MCM-48-25 catalyst is much higher than that of the others. • A maximum phenol conversion of 91.6% was achieved under optimum reaction conditions for SO 4 2− /Zr-MCM-48-25

Gene mdpC plays a regulatory role in the methyl-tert-butyl ether degradation pathway of Methylibium petroleiphilum strain PM1.

Science.gov (United States)

Joshi, Geetika; Schmidt, Radomir; Scow, Kate M; Denison, Michael S; Hristova, Krassimira R

2015-04-01

Among the few bacteria known to utilize methyl tert-butyl ether (MTBE) as a sole carbon source, Methylibium petroleiphilum PM1 is a well-characterized organism with a sequenced genome; however, knowledge of the genetic regulation of its MTBE degradation pathway is limited. We investigated the role of a putative transcriptional activator gene, mdpC, in the induction of MTBE-degradation genes mdpA (encoding MTBE monooxygenase) and mdpJ (encoding tert-butyl alcohol hydroxylase) of strain PM1 in a gene-knockout mutant mdpC(-). We also utilized quantitative reverse transcriptase PCR assays targeting genes mdpA, mdpJ and mdpC to determine the effects of the mutation on transcription of these genes. Our results indicate that gene mdpC is involved in the induction of both mdpA and mdpJ in response to MTBE and tert-butyl alcohol (TBA) exposure in PM1. An additional independent mechanism may be involved in the induction of mdpJ in the presence of TBA. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Synchrotron Photoionization Investigation of the Oxidation of Ethyl tert-Butyl Ether.

Science.gov (United States)

Winfough, Matthew; Yao, Rong; Ng, Martin; Catani, Katherine; Meloni, Giovanni

2017-02-23

The oxidation of ethyl tert-butyl ether (ETBE), a widely used fuel oxygenated additive, is investigated using Cl atoms as initiators in the presence of oxygen. The reaction is carried out at 293, 550, and 700 K. Reaction products are probed by a multiplexed chemical kinetics photoionization mass spectrometer coupled with the synchrotron radiation produced at the Advanced Light Source (ALS) of the Lawrence Berkeley National Laboratory. Products are identified on the basis of mass-to-charge ratio, ionization energies, and shape of photoionization spectra. Reaction pathways are proposed together with detected primary products.

(N-Benzyl-N-ethyl-dithio-carbamato)di-tert-butyl-chloridotin(IV).

Science.gov (United States)

Abdul Muthalib, Amirah Faizah; Baba, Ibrahim; Mohamed Tahir, Mohamed Ibrahim; Tiekink, Edward R T

2011-02-26

The Sn(IV) atom in the title diorganotin dithio-carbamate, [Sn(C(4)H(9))(2)Cl(C(10)H(12)NS(2))], is penta-coordinated by an asymmetrically coordinating dithio-carbamate ligand, a Cl and two C atoms of the Sn-bound tert-butyl groups. The resulting C(2)ClS(2) donor set defines a coordination geometry inter-mediate between square pyramidal and trigonal bipyramidal with a slight tendency towards the former. In the crystal structure, C-H⋯π contacts link centrosymmetrically related mol-ecules into dimeric aggregates.

Pulse radiolysis study of reactions of alkyl and alkylperoxy radicals originating from methyl tert-butyl ether in the gas phase

DEFF Research Database (Denmark)

Langer, S.; Ljungström, E.; Ellermann, T.

1995-01-01

UV spectra and kinetics for the reactions of alkyl and alkylperoxy radicals from methyl tert-butyl ether (MTBE) were studied in 1 atm of SF6 by the pulse radiolysis-UV absorption technique. UV spectra for the radical mixtures were quantified from 215 to 340 nm. At 240 nm, sigma(R) = (2.6 +/- 0.4) X...... and the alkylperoxy radicals with NO and NO2 are (9.1 +/- 1.5) X 10(-13), (4.3 +/- 1.6) X 10(-12) and (1.2 +/- 0.3) X 10(-11) cm(3) molecule(-1) s(-1), respectively. The rate constants given above refer to reaction at the tert-butyl side of the molecule....

1-[(E-2-(5-tert-Butyl-2-hydroxyphenyldiazen-1-yl]naphthalen-2-ol

Directory of Open Access Journals (Sweden)

Hassiba Bougueria

2014-02-01

Full Text Available The non-H atoms of the title compound, C20H20N2O2, is located on a mirror plane except two methyl groups of the tert-butyl group. Intramolecular N—H...O hydrogen bonds exist between the hydroxy and diazenyl groups. In the crystal, molecules are linked by weak C—H...O hydrogen bonds into supramolecular chains running along the a-axis direction.

Facile reactions of gold(i) complexes with tri(tert-butyl)azadiboriridine.

Science.gov (United States)

Shang, Rong; Saito, Souta; Jimenez-Halla, J Oscar C; Yamamoto, Yohsuke

2018-04-17

Direct structural evidence for group 11 metal-mediated B-B bond activation was obtained from reactions of tri(tert-butyl)azadiboriridine (1) with AuCl(L) complexes. The AuCl(SMe2) reaction afforded [η2-B,B-B(tBu)N(tBu)B(tBu)]AuCl (2) by ligand displacement. More donating phosphines as co-ligands led to B-B bond cleavage accompanied by either halide or L migration to form boron-gold complexes 3 (L = PPh3) and 4 (L = PMe3). A similar product 5, which is isostructural to 4, was obtained by the addition of dimethylaminopyridine (DMAP) to 2-4. Complexes 2-5 constitute rare examples of metal complexes bearing two Lewis acidic centres. The effect of the boryl ligand was demonstrated in the formation of a gold(i) complex 6 bearing a 5-membered heterocycle from 3 and tert-butylisonitrile. Plausible reaction mechanisms that led to these complexes and their bonding situation were explored computationally at the DFT level.

Substituted 2,2'-bipyridines by nickel-catalysis: 4,4'-di-tert-butyl-2,2'-bipyridine.

Science.gov (United States)

Buonomo, Joseph A; Everson, Daniel A; Weix, Daniel J

2013-11-01

A simple, ligand-free synthesis of the important bipyridyl ligand 4,4'-di- tert -butyl-2,2'-bipyridine is presented. 5,5'-bis(trifluoromethyl)-2,2'-bipyridine is also synthesized by the same protocol. The syntheses efficiently couple the parent 2-chlorpyridies by a nickel-catalyzed dimerization with manganese powder as the terminal reductant.

Biodegradation of Methyl tert-Butyl Ether by Co-Metabolism with a Pseudomonas sp. Strain

Directory of Open Access Journals (Sweden)

Shanshan Li

2016-09-01

Full Text Available Co-metabolic bioremediation is supposed to be an impressive and promising approach in the elimination technology of methyl tert-butyl ether (MTBE, which was found to be a common pollutant worldwide in the ground or underground water in recent years. In this paper, bacterial strain DZ13 (which can co-metabolically degrade MTBE was isolated and named as Pseudomonas sp. DZ13 based on the result of 16S rRNA gene sequencing analysis. Strain DZ13 could grow on n-alkanes (C5-C8, accompanied with the co-metabolic degradation of MTBE. Diverse n-alkanes with different carbon number showed a significant influence on the degradation rate of MTBE and accumulation of tert-butyl alcohol (TBA. When Pseudomonas sp. DZ13 co-metabolically degraded MTBE with n-pentane as the growth substrate, a higher MTBE-degrading rate (Vmax = 38.1 nmol/min/mgprotein, Ks = 6.8 mmol/L and lower TBA-accumulation was observed. In the continuous degradation experiment, the removal efficiency of MTBE by Pseudomonas sp. Strain DZ13 did not show an obvious decrease after five times of continuous addition.

Sulfuric acid functional zirconium (or aluminum) incorporated mesoporous MCM-48 solid acid catalysts for alkylation of phenol with tert-butyl alcohol

Energy Technology Data Exchange (ETDEWEB)

Jiang, Tingshun, E-mail: tshjiang@mail.ujs.edu.cn; Cheng, Jinlian; Liu, Wangping; Fu, Lie; Zhou, Xuping; Zhao, Qian; Yin, Hengbo

2014-10-15

Several zirconium (or aluminum) incorporated mesoporous MCM-48 solid acid catalysts (SO{sub 4}{sup 2−}/Zr-MCM-48 and SO{sub 4}{sup 2−}/Al-MCM-48) were prepared by the impregnation method and their physicochemical properties were characterized by means of XRD, FT-IR, TEM, NH{sub 3}-TPD and N{sub 2} physical adsorption. Also, the catalytic activities of these solid acid catalysts were evaluated by the alkylation of phenol with tert-butyl alcohol. The effect of weight hour space velocity (WHSV), reaction time and reaction temperature on catalytic properties was also studied. The results show that the SO{sub 4}{sup 2−}/Zr-MCM-48 and SO{sub 4}{sup 2−}/Al-MCM-48 still have good mesoporous structure and long range ordering. Compared with the Zr (or Al)–MCM-48 samples, SO{sub 4}{sup 2−}/Zr-MCM-48 and SO{sub 4}{sup 2−}/Al-MCM-48 solid acid catalysts have strong acidity and exhibit high activities in alkylation reaction of phenol with tert-butyl alcohol. The SO{sub 4}{sup 2−}/Zr-MCM-48-25 (molar ratio of Si/Zr=0.04) catalyst was found to be the most promising and gave the highest phenol conversion among all catalysts. A maximum phenol conversion of 91.6% with 4-tert-butyl phenol (4-TBP) selectivity of 81.8% was achieved when the molar ratio of tert-butyl alcohol:phenol is 2:1, reaction time is 2 h, the WHSV is 2 h{sup −1} and the reaction temperature is 140 °C. - Highlights: • Sulfuric acid functional mesoporous solid acid catalysts were prepared via impregnation method. • The alkylation of phenol with tert-butyl alcohol was carried out over these solid acid catalysts. • The catalytic activity of SO{sub 4}{sup 2−}/Zr-MCM-48-25 catalyst is much higher than that of the others. • A maximum phenol conversion of 91.6% was achieved under optimum reaction conditions for SO{sub 4}{sup 2−}/Zr-MCM-48-25.

Thermochemical studies on two alkyl-bulky substituted xanthene derivatives: 9,9-dimethylxanthene and 2,7-di-tert-butyl-9,9-dimethylxanthene

International Nuclear Information System (INIS)

Freitas, Vera L.S.; Gomes, José R.B.; Ribeiro da Silva, Maria D.M.C.

2017-01-01

Highlights: • Energetic characterization of two alkyl-bulky substituted xanthene derivatives. • Massic energies of combustion of xanthene derivatives. • Enthalpies of sublimation determined by vacuum drop microcalorimetry technique. • Temperature-vapour pressure dependence by mass-loss Knudsen effusion method. • Gas-phase enthalpies of formation of alkyl xanthene derivatives. - Abstract: Thermodynamic properties of 9,9-dimethylxanthene and 2,7-di-tert-butyl-9,9-dimethylxanthene for the condensed and gas states were derived from experimental and computational studies. Static-bomb combustion calorimetry, vacuum drop microcalorimetry and the Knudsen effusion techniques were used. Computational calculations of the enthalpies of hypothetical reactions in the gaseous phase, using the G3(MP2)//B3LYP composite method, were performed for the two xanthene derivatives. Natural bond orbital (NBO) calculations were also performed to ascertain the structure and reactivity of these compounds. The energetic effects caused by replacing hydrogen atoms in the xanthene moiety by methyl and tert-butyl groups yielding 9,9-dimethylxanthene and 2,7-di-tert-butyl-9,9-dimethylxanthene species were determined from direct comparison of their standard (p o = 0.1 MPa) molar enthalpies of formation in the gaseous phase, at T = 298.15 K.

Transcriptomic profiling of chemical exposure reveals roles of Yap1 in protecting yeast cells from oxidative and other types of stresses.

Science.gov (United States)

Zhang, Chao; Li, Zhouquan; Zhang, Xiaohua; Yuan, Li; Dai, Heping; Xiao, Wei

2016-01-01

Transcriptomic profiles are generated by comparing wild-type and the yeast yap1 mutant to various chemicals in an attempt to establish a correlation between this gene mutation and chemical exposure. Test chemicals include ClonNAT as a non-genotoxic agent, methyl methanesulphonate (MMS) as an alkylating agent, tert-butyl hydroperoxide (t-BHP) as an oxidative agent and the mixture of t-BHP and MMS to reflect complex natural exposure. Differentially expressed genes (DEGs) were identified and specific DEGs were obtained by excluding overlapping DEGs with the control group. In the MMS exposure group, deoxyribonucleotide biosynthetic processes were upregulated, while oxidation-reduction processes were downregulated. In the t-BHP exposure group, metabolic processes were upregulated while peroxisome and ion transport pathways were downregulated. In the mixture exposure group, the proteasome pathway was upregulated, while the aerobic respiration was downregulated. Homologue analysis of DEGs related to human diseases showed that many of DEGs were linked to cancer, ageing and neuronal degeneration. These observations confirm that the yap1 mutant is more sensitive to chemicals than wild-type cells and that the susceptible individuals carrying the YAP1-like gene defect may enhance risk to chemical exposure. Hence, this study offers a novel approach to environmental risk assessment, based on the genetic backgrounds of susceptible individuals. Copyright © 2015 John Wiley & Sons, Ltd.

Voltammetric Determination of Nitro Derivative of Synthetic Antioxidant 2,6-di-tert-butyl-4-methyl-phenol

Czech Academy of Sciences Publication Activity Database

Chýlková, J.; Machalický, O.; Tomášková, M.; Šelešovská, R.; Navrátil, Tomáš

2016-01-01

Roč. 49, č. 1 (2016), s. 92-106 ISSN 0003-2719 R&D Projects: GA ČR(CZ) GAP208/12/1645 Institutional support: RVO:61388955 Keywords : 2,6-di-tert-butyl-4-methyl-phenol * handing drop mercury electrode * nitration Subject RIV: CG - Electrochemistry Impact factor: 1.150, year: 2016

Cuscuta chinensis seeds water extraction protecting murine osteoblastic MC3T3-E1 cells against tertiary butyl hydroperoxide induced injury.

Science.gov (United States)

Gao, Jian-mei; Li, Ran; Zhang, Lei; Jia, Li-long; Ying, Xi-xiang; Dou, De-qiang; Li, Jian-chun; Li, Hai-bo

2013-07-09

Cuscuta chinensis (C. chinensis) is a well-known traditional Chinese herb that has been used to treat heart disease, diabetes, liver injury, cancer, and aging. Murine osteoblastic MC3T3-E1 cells were treated with various concentrations of C. chinensis water extraction at different time intervals. The antioxidant effect of C. chinensis on MC3T3-E1 cells was evaluated using MTT and TUNEL assays. The effect of C. chinensis on cell cycle was analyzed by flow cytometry with propidium iodide. Lipid peroxidation was measured by the HPLC method. The cellular redox status was determined from the reduced glutathione to oxidized glutathione ratio (GSH/GSSG) and the enzymes involved in glutathione metabolism, including glutathione reductase (GR), Glutathione S-transferase (GST), and Glucose-6-phosphate dehydrogenase (G6PD). The changes in relative mitochondrial transmembrane potential (ΔΨm) in the MC3T3-E1 cells were analyzed with rhodamine 123 staining. Western blot analysis was used to evaluate the levels of cytochrome c (cyto c), Bax, Bcl-2, caspase 3, Sirt3, and IDH2 expressions. The C. chinensis water extraction protects tertiary butyl hydroperoxide (TBHP)-treated MC3T3-E1 cells from death in a dose-dependent manner. C. chinensis treatment significantly inhibited the reactive oxygen species (ROS) generation, malondialdehyde (MDA) production, and increased the activity of superoxide dismutase (SOD), GR, GST, and G6PD. The release of cyto c from mitochondria was reduced by C. chinensis, which increased the expression of antiapoptotic IDH2, Sirt3, and Bcl-2 and decreased the expression of Bax, cyto c, and caspase 3. C. chinensis modulated the oxidative stress-induced apoptosis in MC3T3-E1 cells, probably due to its antioxidant activity and functioning via mitochondria-dependent pathways. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Structure of methylene chloride addition product to zirconium tetrachloride complex with 1-tert.-butyl-2,4,4-trimethyl-2-thio-trimethylsilyl-1,3,2,4-diazaphosphasilatedine

International Nuclear Information System (INIS)

Brusilovets, A.I.; Rusanov, Eh.B.; Chernega, A.N.

1995-01-01

Complex of zirconium tetrachloride with 1-tert.-butyl-2,4,4-trimethyl--2-thio-3-trimethyl-silyl-1,3,2,4-diazaphosphasilatedine interacts with methylene chloride with formation of bis[3-tert.-butyl-2,4,4-trimethyl-1--trimethylsilyl-2-chloremethylthio-1,3,2,4-diazaphosphasilatedinium] decachlorodizirconate. Specific features of crystal and molecular structure of the compound prepared have been studied by X-ray diffraction method. 21 refs.; 2 figs.; 2 tabs

U.S. Geological Survey laboratory method for methyl tert-Butyl ether and other fuel oxygenates

Science.gov (United States)

Raese, Jon W.; Rose, Donna L.; Sandstrom, Mark W.

1995-01-01

Methyl tert-butyl ether (MTBE) was found in shallow ground-water samples in a study of 8 urban and 20 agricultural areas throughout the United States in 1993 and 1994 (Squillace and others, 1995, p. 1). The compound is added to gasoline either seasonally or year round in many parts of the United States to increase the octane level and to reduce carbon monoxide and ozone levels in the air. The U.S. Geological Survey (USGS) National Water Quality Laboratory (NWQL), near Denver, uses state-of-the-art technology to analyze samples for MTBE as part of the USGS water-quality studies. In addition, the NWQL offers custom analyses to determine two other fuel oxygenates--ethyl tert-butyl ether (ETBE) and tert-amyl methyl ether (TAME). The NWQL was not able to obtain a reference standard for tert-amyl ethyl ether (TAEE), another possible fuel oxygenate (Shelley and Fouhy, 1994, p. 63). The shallow ground-water samples were collected as part of the USGS National Water-Quality Assessment Program. These samples were collected from 211 urban wells or springs and 562 agricultural wells sampled by the USGS in 1993 and 1994. The wells were keyed to specific land-use areas to assess the effects of different uses on ground-water quality (Squillace and others, 1995, p. 2). Ground-water samples were preserved on site to pH less than or equal to 2 with a solution of 1:1 hydrochloric acid. All samples were analyzed at the NWQL within 2 weeks after collection. The purpose of this fact sheet is to explain briefly the analytical method implemented by the USGS for determining MTBE and other fuel oxygenates. The scope is necessarily limited to an overview of the analytical method (instrumentation, sample preparation, calibration and quantitation, identification, and preservation of samples) and method performance (reagent blanks, accuracy, and precision).

Sensitivity of photoelectron diffraction to conformational changes of adsorbed molecules: Tetra-tert-butyl-azobenzene/Au(111

Directory of Open Access Journals (Sweden)

A. Schuler

2017-01-01

Full Text Available Electron diffraction is a standard tool to investigate the atomic structure of surfaces, interfaces, and adsorbate systems. In particular, photoelectron diffraction is a promising candidate for real-time studies of structural dynamics combining the ultimate time resolution of optical pulses and the high scattering cross-sections for electrons. In view of future time-resolved experiments from molecular layers, we studied the sensitivity of photoelectron diffraction to conformational changes of only a small fraction of molecules in a monolayer adsorbed on a metallic substrate. 3,3′,5,5′-tetra-tert-butyl-azobenzene served as test case. This molecule can be switched between two isomers, trans and cis, by absorption of ultraviolet light. X-ray photoelectron diffraction patterns were recorded from tetra-tert-butyl-azobenzene/Au(111 in thermal equilibrium at room temperature and compared to patterns taken in the photostationary state obtained by exposing the surface to radiation from a high-intensity helium discharge lamp. Difference patterns were simulated by means of multiple-scattering calculations, which allowed us to determine the fraction of molecules that underwent isomerization.

SYNTHESIS OF METHYL TERT-BUTYL ETHER CATALYZED BY ACIDIC ION-EXCHANGE RESINS - INFLUENCE OF THE PROTON ACTIVITY

NARCIS (Netherlands)

PANNEMAN, HJ; BEENACKERS, AACM

1995-01-01

The catalytic activity of various strong acid ion-exchange resins on the synthesis of methyl tert-butyl ether (MtBE) from methanol and isobutene has been investigated. Relative to Amberlyst 15, Kastel CS 381 and Amberlyst CSP have similar rate constants, whereas Duolite ES 276 and Amberlyst XE 307

Interaction between t-butyl hydroperoxide (I) and positive halogen compounds. part I. Intermediates in the reaction between I and CI2O

NARCIS (Netherlands)

Ham, J. van; Schors, A.; Kooyman, E.C.

1973-01-01

“positive halogen” compounds were found to induce the decomposition of t-butyl hydroperoxide (I) in the dark. In this Cl2O proved to be particularly effective, liberating oxygen from I instantaneously at 0°. At temperature between −80° and −30°, two oxygen-rich intermediates could be observed with

Reactive Imprint Lithography: Combined Topographical Patterning and Chemical Surface Functionalization of Polystyrene-block-poly(tert-butyl acrylate) Films

NARCIS (Netherlands)

Duvigneau, Joost; Cornelissen, Stijn; Bardajı´Valls, Nuria; Schönherr, Holger; Vancso, Gyula J.

2009-01-01

Here, reactive imprint lithography (RIL) is introduced as a new, one-step lithographic tool for the fabrication of large-area topographically patterned, chemically activated polymer platforms. Films of polystyrene-block-poly(tert-butyl acrylate) (PS-b-PtBA) are imprinted with PDMS master stamps at

Volumetric Behaviour of the Ternary System (Methyl Tert-butyl ether + Methylbenzene + Butan-1-ol) and Its Binary sub-System (Methyl Tert-Butyl Ether + Butan-1-ol) within the Temperature Range (298.15–328.15) K

Czech Academy of Sciences Publication Activity Database

Morávková, Lenka; Troncoso, J.; Škvorová, M.; Havlica, Jaromír; Petrus, P.; Sedláková, Zuzana

2015-01-01

Roč. 90, NOV 2015 (2015), s. 59-70 ISSN 0021-9614 R&D Projects: GA ČR(CZ) GAP105/12/0664; GA MŠk(CZ) LD14094 Grant - others:GNIL(IT) 408 REGALIs (CN2012/120) Institutional support: RVO:67985858 Keywords : methylbenzene * density * methyl-tert-butyl ether Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.196, year: 2015

INTERACTION OF METHYL-TERT BUTYL ETHER AND WATER STRESS ON SEED GERMINATION AND SEEDLING GROWTH IN SOIL MICROCOSMS

Science.gov (United States)

Methyl tert-butyl ether (MTBE) is a widespread contaminant in surface and ground water in the United States. Frequently irrigation is used to water fields to germinate planted seeds and sustain plant growth. A likely possibility exists that water used may have some MTBE. Our s...

Impact of organic hydroperoxides on rat testicular tissue and ...

African Journals Online (AJOL)

The effects of hydroperoxides on testicular tissue and epididymal sperm were investigated. Male Wistar rats aged 10 - 12 weeks were randomly placed in groups and received standard rat chow and water ad libitum. Animals were injected intraperitoneally with saline (0.5 ml), t-butyl hydroperoxide (5, 10, 20 and 40 ìM; 0.5 ...

Involvement of a novel enzyme, MdpA, in methyl tert-butyl ether degradation in Methylibium petroleiphilum PM1.

Science.gov (United States)

Schmidt, Radomir; Battaglia, Vince; Scow, Kate; Kane, Staci; Hristova, Krassimira R

2008-11-01

Methylibium petroleiphilum PM1 is a well-characterized environmental strain capable of complete metabolism of the fuel oxygenate methyl tert-butyl ether (MTBE). Using a molecular genetic system which we established to study MTBE metabolism by PM1, we demonstrated that the enzyme MdpA is involved in MTBE removal, based on insertional inactivation and complementation studies. MdpA is constitutively expressed at low levels but is strongly induced by MTBE. MdpA is also involved in the regulation of tert-butyl alcohol (TBA) removal under certain conditions but is not directly responsible for TBA degradation. Phylogenetic comparison of MdpA to related enzymes indicates close homology to the short-chain hydrolyzing alkane hydroxylases (AH1), a group that appears to be a distinct subfamily of the AHs. The unique, substrate-size-determining residue Thr(59) distinguishes MdpA from the AH1 subfamily as well as from AlkB enzymes linked to MTBE degradation in Mycobacterium austroafricanum.

An investigation into the Ti-grafting structure on MCM-41 and epoxidation catalysis

DEFF Research Database (Denmark)

Yuan, Q.C.; Hagen, A.; Roessner, F.

2006-01-01

The structure of titanium species grafted on a purely siliceous MCM-41 and their catalysis in the epoxidation of cyclohexene with tert-butyl hydroperoxide (TBHP) were investigated. FT-IR, XANES and UV-vis were used for the examination of the Ti-grafted MCM-41. The results indicated...... that the titanium atoms are grafted on the wall surface of the MCM-41 by four-fold coordination. The four-fold coordinated titanium species are mainly grafted by two or one -O-Si-O- bridges on the MCM-41, resulting in so-called bipodal or monopodal titanium centres in partially polymerised states. The ratio...... of monopodal to bipodal titanium increases with the increase in Ti-content. These partially polymerised titanium species considered as catalytic active centres have high activity and selectivity in the epoxidation reaction. The used Ti-grafted MCM-41 samples were regenerated by heating in nitrogen or air...

In vitro and in vivo hepatoprotective effect of ganodermanontriol against t-BHP-induced oxidative stress

DEFF Research Database (Denmark)

Ha, Do Thi; Oh, Joonseok; Khoi, Nguyen Minh

2013-01-01

the evaluation of hepatoprotective activity of ganodermanontriol, a sterol isolated from Ganoderma lucidum, and the investigation of its mechanism of action in Hepa1c1c7 and murine liver cells upon tert-butyl hydroperoxide (t-BHP)-induced inflammation. t-BHP was utilized to stimulate an anti...... were monitored to assess whether GDT protected the cells from the t-BHP-mediated oxidative stimuli. RESULTS: GDT induced HO-1 expression via the activation of Nrf-2 nuclear translocation and the subsequent transcription of the HO-1 gene in vitro and in vivo, which seemed to be regulated...... the ethnopharmacological application of Ganoderma lucidum as a treatment for hepatic disorders. GDT induced in vitro and in vivo anti-inflammatory activity in t-BHP-damaged hepatic cells through the expression of HO-1, and in which PI3K/Akt and p38 kinases are involved. Our study motivates further research...

Overview of technologies for removal of methyl tert-butyl ether (MTBE) from water.

Science.gov (United States)

Levchuk, Irina; Bhatnagar, Amit; Sillanpää, Mika

2014-04-01

Wide use of methyl tert-butyl ether (MTBE) as fuel oxygenates leads to worldwide environment contamination with this compound basically due to fuel leaks from storage or pipelines. Presence of MTBE in drinking water is of high environmental and social concern. Existing methods for MTBE removal from water have a number of limitations which can be possibly overcome in the future with use of emerging technologies. This work aims to provide an updated overview of recent developments in technologies for MTBE removal from water. Copyright © 2014. Published by Elsevier B.V.

Di-tert-butyl 2,2′-(biphenyl-2,2′-diyldioxydiacetate

Directory of Open Access Journals (Sweden)

Qamar Ali

2008-08-01

Full Text Available The title compound, C24H30O6, does not exhibit π–π interactions due to the steric effect of the bulky tert-butyl groups present in the molecule. The presence of these groups at the 2 and 2′ positions hinders the free motion of the benzene rings relative to each other, causing them to adopt an antiperiplanar arrangement. The benzene rings are twisted by just under 50.96 (17° with respect to each other. The carbonyl groups within the molecule are directed in different directions, one towards the biphenyl group and the other away from it. The molecules are linked together by C=O...H—C hydrogen bonds.

Enhancement of methyl tert-butyl ether degradation by the addition of readily metabolizable organic substrates

International Nuclear Information System (INIS)

Chen Dongzhi; Chen Jianmeng; Zhong Weihong

2009-01-01

Supplements with readily metabolizable organic substrates were investigated to increase the biomass and enhance degradation of methyl tert-butyl ether (MTBE) due to the low biomass yield of MTBE which has been one of the factors for low-rate MTBE degradation. The influence of various organic substrates on the rate of aerobic degradation of methyl tert-butyl ether (MTBE) by Methylibium petroleiphilum PM1 was investigated, and only yeast extract (YE), beef extract and tryptone exhibited stimulatory effect. With the concentration of each substrate being 100 mg/L, the average MTBE removal rate could increase to 1.29, 1.20 and 1.04 mg/(L h), respectively, in comparison with 0.71 mg/(L h) when carried out in medium without addition. The stimulatory effects of YE addition, as well as induction period required by MTBE degradation, varied dramatically with the storage conditions, pre-culture medium and concentrations of the inoculums. The extent of stimulatory effects of YE might be closely related to the proportion of induction period in the total time of MTBE-degradation. The removal efficiency increased from about 50% to 90.5% with the addition of YE in a packed-bed reactor loaded with calcium alginate immobilized cells.

Di-tert-butyl­chlorido(N,N-dibenzyl­dithio­carbamato)tin(IV)

Science.gov (United States)

Abdul Muthalib, Amirah Faizah; Baba, Ibrahim; Mohamed Tahir, Mohamed Ibrahim; Tiekink, Edward R. T.

2011-01-01

The SnIV atom in the title diorganotin dithio­carbamate, [Sn(C4H9)2(C15H14NS2)Cl], is penta­coordinated by an asymmetrically coordinating dithio­carbamate ligand, a Cl atom and two C atoms of the Sn-bound tert-butyl groups. The resulting C2ClS2 donor set defines a coordination geometry inter­mediate between square pyramidal and trigonal bipyramidal with a slight tendency towards the former. PMID:21522304

Novel process window for the safe and continuous synthesis of tert.-butyl peroxy pivalate in a micro reactor

NARCIS (Netherlands)

Illg, T.; Hessel, V.; Löb, P.; Schouten, J.C.

2011-01-01

In this paper, the two step synthesis of tert.-butyl peroxy pivalate using two different flow regimes is introduced, in particular the use of "segmented flow" and the concept of "dispersed flow". The use of the segmented flow process, in this case, is challenging due to the very low interfacial

Antioxidant action of 3-mercapto-5H-1,2,4-triazino[5,6-b]indole-5-acetic acid, an efficient aldose reductase inhibitor, in a 1,1'-diphenyl-2-picrylhydrazyl assay and in the cellular system of isolated erythrocytes exposed to tert-butyl hydroperoxide.

Science.gov (United States)

Prnova, Marta Soltesova; Ballekova, Jana; Majekova, Magdalena; Stefek, Milan

2015-01-01

The subject of this study was 3-mercapto-5H-1,2,4-triazino[5,6-b]indole-5-acetic acid (compound 1), an efficient aldose reductase inhibitor of high selectivity. The antioxidant action of 1 was investigated in greater detail by employing a 1,1'-diphenyl-2-picrylhydrazyl (DPPH) test and in the system of isolated rat erythrocytes. First, the compound was subjected to the DPPH test. Second, the overall antioxidant action of the compound was studied in the cellular system of isolated rat erythrocytes oxidatively stressed by free radicals derived from the lipophilic tert-butyl hydroperoxide. The uptake kinetics of 1 was studied and osmotic fragility of the erythrocytes was evaluated. The DPPH test revealed significant antiradical activity of 1. One molecule of 1 was found to quench 1.48 ± 0.06 DPPH radicals. In the system of isolated erythrocytes, the compound was readily taken up by the cells followed by their protection against free radical-initiated hemolysis. Osmotic fragility of the erythrocytes was not affected by 1. The results demonstrated the ability of 1 to scavenge DPPH and to protect intact erythrocytes against oxidative damage induced by peroxyl radicals. By affecting both the polyol pathway and oxidative stress, the compound represents an example of a promising agent for multi-target pharmacology of diabetic complications.

Involvement of a Novel Enzyme, MdpA, in Methyl tert-Butyl Ether Degradation in Methylibium petroleiphilum PM1 ▿

Science.gov (United States)

Schmidt, Radomir; Battaglia, Vince; Scow, Kate; Kane, Staci; Hristova, Krassimira R.

2008-01-01

Methylibium petroleiphilum PM1 is a well-characterized environmental strain capable of complete metabolism of the fuel oxygenate methyl tert-butyl ether (MTBE). Using a molecular genetic system which we established to study MTBE metabolism by PM1, we demonstrated that the enzyme MdpA is involved in MTBE removal, based on insertional inactivation and complementation studies. MdpA is constitutively expressed at low levels but is strongly induced by MTBE. MdpA is also involved in the regulation of tert-butyl alcohol (TBA) removal under certain conditions but is not directly responsible for TBA degradation. Phylogenetic comparison of MdpA to related enzymes indicates close homology to the short-chain hydrolyzing alkane hydroxylases (AH1), a group that appears to be a distinct subfamily of the AHs. The unique, substrate-size-determining residue Thr59 distinguishes MdpA from the AH1 subfamily as well as from AlkB enzymes linked to MTBE degradation in Mycobacterium austroafricanum. PMID:18791002

Redox Active Transition Metal ions Make Melanin Susceptible to Chemical Degradation Induced by Organic Peroxide.

Science.gov (United States)

Zadlo, Andrzej; Pilat, Anna; Sarna, Michal; Pawlak, Anna; Sarna, Tadeusz

2017-12-01

With aging, retinal pigment epithelium melanosomes, by fusion with the age pigment lipofuscin, form complex granules called melanolipofuscin. Lipofuscin granules may contain oxidized proteins and lipid hydroperoxides, which in melanolipofuscin could chemically modify melanin polymer, while transition metal ions present in melanin can accelerate such oxidative modifications. The aim of this research was to examine the effect of selected transition metal ions on melanin susceptibility to chemical modification induced by the water-soluble tert-butyl hydroperoxide used as an oxidizing agent. Synthetic melanin obtained by DOPA autooxidation and melanosomes isolated from bovine retinal pigment epithelium were analyzed. To monitor tert-butyl hydroperoxide-induced oxidative changes of DMa and BMs, electron paramagnetic resonance spectroscopy, UV-vis absorption spectroscopy, dynamic light scattering, atomic force microscopy and electron paramagnetic resonance oximetry were employed. These measurements revealed that both copper and iron ions accelerated chemical degradation induced by tert-butyl hydroperoxide, while zinc ions had no effect. Strong prooxidant action was detected only in the case of melanosomes and melanin degraded in the presence of iron. It can be postulated that similar chemical processes, if they occur in situ in melanolipofuscin granules of the human retinal pigment epithelium, would modify antioxidant properties of melanin and its reactivity.

UV absorption spectra and kinetics for alkyl and alkyl peroxy radicals originating from di-tert-butyl ether

DEFF Research Database (Denmark)

Nielsen, O.J.; Sehested, J.; Langer, S.

1995-01-01

Alkyl, (CH3)(3)COC(CH3)(2)CH2, and alkyl peroxy, (CH3)(3)COC(CH3)(2)CH2O2, radicals from di-tert-butyl ether (DTBE), have been studied in the gas phase at 296 K. A pulse radiolysis UV absorption technique was used to measure the spectra and kinetics. Absorption cross sections were quantified over...

Effect of benzene, toluene, ethylbenzene, and p-xylene (BTEX) mixture on biodegradation of methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA) by pure culture UC1.

Science.gov (United States)

Pruden, Amy; Suidan, Makram

2004-08-01

The effect of a BTEX mixture on the biodegradation of methyl tert-butyl ether (MTBE) and its degradation intermediate, tert-butyl alcohol (TBA) was investigated in the pure bacterial culture UC1, which has been identified to be a strain of the known MTBE-degrader PM1 based on greater than 99% 16S rDNA similarity. Several degradation studies were carried out on UC1 at three initial concentration levels of MTBE or TBA: 6-7; 15-17; and 40-45 mg/l, both with and without BTEX present cumulatively at about half of the MTBE or TBA molar mass in the system. The BTEX mixture was observed not to affect either the rate or the degradation lag period of MTBE or TBA degradation, except that the TBA degradation rate actually increased when BTEX was present initially in the highest concentration studies. When serving as the sole substrate, the MTBE degradation rate ranged from 48 +/- 1.2 to 200 +/- 7.0 mg(MTBE)/g(dw) h, and the TBA degradation rate from 140 +/- 18 to 530 +/- 70 mg(TBA)/g(dw) h. When present with BTEX, MTBE and TBA rates ranged from 46 +/- 2.2 to 210 +/- 14 and 170 +/- 28 to 780 +/- 43 mg(TBA)/g(dw) h, respectively. In studies where varying concentrations of TBA were present with 5 mg/l MTBE, both compounds were degraded simultaneously with no obvious preference for either substrate. In the highest concentration study of TBA with 5 mg/l MTBE, BTEX was also observed to increase the ultimate rate of TBA degradation. In addition to exploring the affect of BTEX, this study also provides general insight into the metabolism of MTBE and TBA by pure culture UC1.

Screening SIRT1 Activators from Medicinal Plants as Bioactive Compounds against Oxidative Damage in Mitochondrial Function

Directory of Open Access Journals (Sweden)

Yi Wang

2016-01-01

Full Text Available Sirtuin type 1 (SIRT1 belongs to the family of NAD+ dependent histone deacetylases and plays a critical role in cellular metabolism and response to oxidative stress. Traditional Chinese medicines (TCMs, as an important part of natural products, have been reported to exert protective effect against oxidative stress in mitochondria. In this study, we screened SIRT1 activators from TCMs and investigated their activities against mitochondrial damage. 19 activators were found in total by in vitro SIRT1 activity assay. Among those active compounds, four compounds, ginsenoside Rb2, ginsenoside F1, ginsenoside Rc, and schisandrin A, were further studied to validate the SIRT1-activation effects by liquid chromatography-mass spectrometry and confirm their activities against oxidative damage in H9c2 cardiomyocytes exposed to tert-butyl hydroperoxide (t-BHP. The results showed that those compounds enhanced the deacetylated activity of SIRT1, increased ATP content, and inhibited intracellular ROS formation as well as regulating the activity of Mn-SOD. These SIRT1 activators also showed moderate protective effects on mitochondrial function in t-BHP cells by recovering oxygen consumption and increasing mitochondrial DNA content. Our results suggested that those compounds from TCMs attenuated oxidative stress-induced mitochondrial damage in cardiomyocytes through activation of SIRT1.

Biodegradation of methyl tert-butyl ether by Kocuria sp.

Directory of Open Access Journals (Sweden)

Kiković Dragan D.

2012-01-01

Full Text Available Methyl tert-butyl ether (MTBE has been used to replace the toxic compounds from gasoline and to reduce emission of air pollutants. Due to its intensive use, MTBE has become one of the most important environment pollutants. The aim of this paper is isolation and identification of the bacteria from wastewater sample of “HIP Petrohemija” Pančevo (Serbia, capable of MTBE biodegradation. The results of the investigation showed that only the bacterial isolate 27/1 was capable of growth on MTBE. The result of sequence analyzes of 16S rDNA showed that this bacterial isolate belongs to the Kocuria sp. After the incubation period of 86 days, the degradation rates of initial MTBE concentration of 25 and 125 μg/ml were 55 and 36%, respectively. These results indicated that bacteria Kocuria sp. is successfully adapted on MTBE and can be potentially used in bioremediation of soils and waters contaminated with MTBE.

Design and Control of Glycerol-tert-Butyl Alcohol Etherification Process

Directory of Open Access Journals (Sweden)

Elena Vlad

2012-01-01

Full Text Available Design, economics, and plantwide control of a glycerol-tert-butyl alcohol (TBA etherification plant are presented. The reaction takes place in liquid phase, in a plug flow reactor, using Amberlyst 15 as a catalyst. The products' separation is achieved by two distillation columns where high-purity ethers are obtained and a section involving extractive distillation with 1,4-butanediol as solvent, which separates TBA from the TBA/water azeotrope. Details of design performed in AspenPlus and an economic evaluation of the process are given. Three plantwide control structures are examined using a mass balance model of the plant. The preferred control structure fixes the fresh glycerol flow rate and the ratio glycerol + monoether : TBA at reactor-inlet. The stability and robustness in the operation are checked by rigorous dynamic simulation in AspenDynamics.

Substituted 2,2′-bipyridines by nickel-catalysis: 4,4′-di-tert-butyl-2,2′-bipyridine

OpenAIRE

Buonomo, Joseph A.; Everson, Daniel A.; Weix, Daniel J.

2013-01-01

A simple, ligand-free synthesis of the important bipyridyl ligand 4,4′-di-tert-butyl-2,2′-bipyridine is presented. 5,5′-bis(trifluoromethyl)-2,2′-bipyridine is also synthesized by the same protocol. The syntheses efficiently couple the parent 2-chlorpyridies by a nickel-catalyzed dimerization with manganese powder as the terminal reductant.

(N-Benzyl-N-ethyl­dithio­carbamato)di-tert-butyl­chloridotin(IV)

OpenAIRE

Abdul Muthalib, Amirah Faizah; Baba, Ibrahim; Mohamed Tahir, Mohamed Ibrahim; Tiekink, Edward R. T.

2011-01-01

The SnIV atom in the title diorganotin dithio­carbamate, [Sn(C4H9)2Cl(C10H12NS2)], is penta­coordinated by an asymmetrically coordinating dithio­carbamate ligand, a Cl and two C atoms of the Sn-bound tert-butyl groups. The resulting C2ClS2 donor set defines a coordination geometry inter­mediate between square pyramidal and trigonal bipyramidal with a slight tendency towards the former. In the crystal structure, C—H⋯π contacts link centrosymmetrically related mol­ecules into dimeric aggregates...

NecroX-7 prevents oxidative stress-induced cardiomyopathy by inhibition of NADPH oxidase activity in rats

Energy Technology Data Exchange (ETDEWEB)

Park, Joonghoon; Park, Eok; Ahn, Bong-Hyun; Kim, Hyoung Jin [LG Life Sciences Ltd., R and D Park, Daejeon, 305-380 (Korea, Republic of); Park, Ji-hoon [Department of Biochemistry, School of Medicine, Chungnam National University, Daejeon, 301-747 (Korea, Republic of); Koo, Sun Young; Kwak, Hyo-Shin; Park, Heui Sul; Kim, Dong Wook; Song, Myoungsub; Yim, Hyeon Joo; Seo, Dong Ook [LG Life Sciences Ltd., R and D Park, Daejeon, 305-380 (Korea, Republic of); Kim, Soon Ha, E-mail: shakim@lgls.com [LG Life Sciences Ltd., R and D Park, Daejeon, 305-380 (Korea, Republic of)

2012-08-15

Oxidative stress is one of the causes of cardiomyopathy. In the present study, NecroXs, novel class of mitochondrial ROS/RNS scavengers, were evaluated for cardioprotection in in vitro and in vivo model, and the putative mechanism of the cardioprotection of NecroX-7 was investigated by global gene expression profiling and subsequent biochemical analysis. NecroX-7 prevented tert-butyl hydroperoxide (tBHP)-induced death of H9C2 rat cardiomyocytes at EC{sub 50} = 0.057 μM. In doxorubicin (DOX)-induced cardiomyopathy in rats, NecroX-7 significantly reduced the plasma levels of creatine kinase (CK-MB) and lactate dehydrogenase (LDH) which were increased by DOX treatment (p < 0.05). Microarray analysis revealed that 21 genes differentially expressed in tBHP-treated H9C2 cells were involved in ‘Production of reactive oxygen species’ (p = 0.022), and they were resolved by concurrent NecroX-7 treatment. Gene-to-gene networking also identified that NecroX-7 relieved cell death through Ncf1/p47phox and Rac2 modulation. In subsequent biochemical analysis, NecroX-7 inhibited NADPH oxidase (NOX) activity by 53.3% (p < 0.001). These findings demonstrate that NecroX-7, in part, provides substantial protection of cardiomyopathy induced by tBHP or DOX via NOX-mediated cell death. -- Highlights: ► NecroX-7 prevented tert-butyl hydroperoxide-induced in vitro cardiac cell death. ► NecroX-7 ameliorated doxorubicin-induced in vivo cardiomyopathy. ► NecroX-7 prevented oxidative stress and necrosis-enriched transcriptional changes. ► NecroX-7 effectively inhibited NADPH oxidase activation. ► Cardioprotection of Necro-7 was brought on by modulation of NADPH oxidase activity.

Sulindac enhances the killing of cancer cells exposed to oxidative stress.

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Maria Marchetti

2009-06-01

Full Text Available Sulindac is an FDA-approved non-steroidal anti-inflammatory drug (NSAID that affects prostaglandin production by inhibiting cyclooxygenases (COX 1 and 2. Sulindac has also been of interest for more than decade as a chemopreventive for adenomatous colorectal polyps and colon cancer.Pretreatment of human colon and lung cancer cells with sulindac enhances killing by an oxidizing agent such as tert-butyl hydroperoxide (TBHP or hydrogen peroxide. This effect does not involve cyclooxygenase (COX inhibition. However, under the conditions used, there is a significant increase in reactive oxygen species (ROS within the cancer cells and a loss of mitochondrial membrane potential, suggesting that cell death is due to apoptosis, which was confirmed by Tunel assay. In contrast, this enhanced killing was not observed with normal lung or colon cells.These results indicate that normal and cancer cells handle oxidative stress in different ways and sulindac can enhance this difference. The combination of sulindac and an oxidizing agent could have therapeutic value.

Antioxidant Effects of Sheep Whey Protein on Endothelial Cells

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Efthalia Kerasioti

2016-01-01

Full Text Available Excessive production of reactive oxygen species (ROS may cause endothelial dysfunction and consequently vascular disease. In the present study, the possible protective effects of sheep whey protein (SWP from tert-butyl hydroperoxide- (tBHP- induced oxidative stress in endothelial cells (EA.hy926 were assessed using oxidative stress biomarkers. These oxidative stress biomarkers were glutathione (GSH and ROS levels determined by flow cytometry. Moreover, thiobarbituric acid-reactive substances (TBARS, protein carbonyls (CARB, and oxidized glutathione (GSSG were determined spectrophotometrically. The results showed that SWP at 0.78, 1.56, 3.12, and 6.24 mg of protein mL−1 increased GSH up to 141%, while it decreased GSSG to 46.7%, ROS to 58.5%, TBARS to 52.5%, and CARB to 49.0%. In conclusion, the present study demonstrated for the first time that SWP protected endothelial cells from oxidative stress. Thus, SWP may be used for developing food supplements or biofunctional foods to attenuate vascular disturbances associated with oxidative stress.

Photoelectric conversion and electrochromic properties of lutetium tetrakis(tert-butyl)bisphthalocyaninate

International Nuclear Information System (INIS)

Hu, Andrew Teh; Hu Tenyi; Liu Lungchang

2003-01-01

Both photoelectric and electrochromic effects on lutetium tetrakis(tert-butyl)bisphthalocyaninate (Lu(TBPc) 2 ) have been carried out in this study. Lu(TBPc) 2 is known for its electrochromic performance, but its photoelectric effect has not mentioned in the literature. The electrochromic properties of Lu(TBPc) 2 have been measured by cyclic voltammetry (CV) and UV-Vis spectrometer at the same time. It takes less than 1.5 s for the color to change from red to green under 0.9 V. Its cycle life is at least over 500 times. Furthermore, we also investigate its photoelectric conversion properties. Its photoelectric cell exhibits a positive photo-electricity conversion effect with a short-circuit photocurrent (46.4 μA/cm 2 ) under illumination of white light (1.201 mW/cm 2 )

Substituted 2,2′-bipyridines by nickel-catalysis: 4,4′-di-tert-butyl-2,2′-bipyridine

Science.gov (United States)

Buonomo, Joseph A.; Everson, Daniel A.; Weix, Daniel J.

2014-01-01

A simple, ligand-free synthesis of the important bipyridyl ligand 4,4′-di-tert-butyl-2,2′-bipyridine is presented. 5,5′-bis(trifluoromethyl)-2,2′-bipyridine is also synthesized by the same protocol. The syntheses efficiently couple the parent 2-chlorpyridies by a nickel-catalyzed dimerization with manganese powder as the terminal reductant. PMID:25221358

Influence Of Initiator Types And Emulsion Polymerization Techniques To Particle Size Of Copolymerization Styrene-Butyl Acrylate-Methyl Methacrylate

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Ariyanti Sarwono

2008-11-01

Full Text Available Influence of initiator types and emulsion polymerization techniques to particle size of copolymerization styrene-butyl acrylate-methyl methacrylate. Copoly(styrene/butyl acrylic/methyl methacrylic was prepared by emulsion polymerization method. This paper describes effect of insiator types i.e. ammonium persulfate (APS, hydrogen peroxide, ters-butyl peroxide (TBHP, initiator redox (H2O2/ascorbic acid and polymerization techniques i.e. batch and semicontinue to particle size distribution of copoly(styrene/butyl acrylic/methyl methacrylic. Initiator TBHP and H2O2 could not initiate copolymerization properly, but initiator APS and redox initiate copolymerization with batch and semi continue techniques could well perform. The higher concentration of APS, the greater particle size of the copolymer, but the copolymer is polymodal. Initiator redox (H2O2/ascorbic acid produced greater particle size than initiator redox (ascorbic acid/ H2O2.

(N-Benzyl-N-ethyl­dithio­carbamato)di-tert-butyl­chloridotin(IV)

Science.gov (United States)

Abdul Muthalib, Amirah Faizah; Baba, Ibrahim; Mohamed Tahir, Mohamed Ibrahim; Tiekink, Edward R. T.

2011-01-01

The SnIV atom in the title diorganotin dithio­carbamate, [Sn(C4H9)2Cl(C10H12NS2)], is penta­coordinated by an asymmetrically coordinating dithio­carbamate ligand, a Cl and two C atoms of the Sn-bound tert-butyl groups. The resulting C2ClS2 donor set defines a coordination geometry inter­mediate between square pyramidal and trigonal bipyramidal with a slight tendency towards the former. In the crystal structure, C—H⋯π contacts link centrosymmetrically related mol­ecules into dimeric aggregates. PMID:21522295

Microbial community composition during anaerobic mineralization of tert-butyl alcohol (TBA) in fuel-contaminated aquifer material.

Science.gov (United States)

Wei, Na; Finneran, Kevin T

2011-04-01

Anaerobic mineralization of tert-butyl alcohol (TBA) and methyl tert-butyl ether (MTBE) were studied in sediment incubations prepared with fuel-contaminated aquifer material. Microbial community compositions in all incubations were characterized by amplified ribosomal DNA restriction analysis (ARDRA). The aquifer material mineralized 42.3±9.9% of [U-(14)C]-TBA to 14CO2 without electron acceptor amendment. Fe(III), sulfate, and Fe(III) plus anthraquinone-2,6-disulfonate addition also promoted U-[14C]-TBA mineralization at levels similar to those of the unamended controls. Nitrate actually inhibited TBA mineralization relative to unamended controls. In contrast to TBA, [U-(14)C]-MTBE was not significantly mineralized in 400 days regardless of electron acceptor amendment. Microbial community analysis indicated that the abundance of one dominant clone group correlated closely with anaerobic TBA mineralization. The clone was phylogenetically distinct from known aerobic TBA-degrading microorganisms, Fe(III)- or sulfate-reducing bacteria. It was most closely associated with organisms belonging to the alphaproteobacteria. Microbial communities were different in MTBE and TBA amended incubations. Shannon indices and Simpson indices (statistical community comparison tools) both demonstrated that microbial community diversity decreased in incubations actively mineralizing TBA, with distinct "dominant" clones developing. These data contribute to our understanding of anaerobic microbial transformation of fuel oxygenates in contaminated aquifer material and the organisms that may catalyze the reactions.

Degradation of the fungicide denmert (S-n-butyl S'-p-tert-butylbenzyl N-3-pyridyldithiocarbonimidate, S-1358) by plants, soils and light

International Nuclear Information System (INIS)

Ohkawa, Hideo; Shibaike, Reiko; Okihara, Yukiko; Morikawa, Michihide; Miyamoto, Junshi

1976-01-01

14 C-Denmert(S-n-butyl S'-p-tert-butylbenzyl N-3-pyridyldithiocarbonimidate, S-1358) labeled at the methylene of the benzyl group was gradually decomposed to yield a number of products, when exposed to sunlight on thin-layer plates or in water solution, applied to plant foliage or nutrient solution, and added to soils under upland conditions. The identified products were almost common to plants, soils and light. The primary reactions occurred: (1), oxidation of the sulfur atoms; (2), cleavage of the dithiocarbonimidate linkage, and (3), oxidation of the methylene of the benzyl group. Also, hydroxylation at the tert-butyl group attached to the benzyl moiety slightly took place in soils. Although radioactivity was absorbed by the plant through leaves or roots, translocation into other parts of the plant occurred to a very small extent. Denmert and its degradation products were hardly leached through the acidic soils tested. (auth.)

Bromine catalyzed conversion of S-tert-butyl groups into versatile and, for self-assembly processes accessible, acetyl-protected thiols.

Science.gov (United States)

Blaszczyk, Alfred; Elbing, Mark; Mayor, Marcel

2004-10-07

The facile and efficient conversion of a tert-butyl protecting group to an acetyl protecting group for thiols by catalytic amounts of bromine in acetyl chloride and the presence of acetic acid has been developed. The fairly mild reaction conditions are of particular interest for new protecting group strategies for sulfur functionalised target structures. Copyright 2004 The Royal Society of Chemistry

Azobenzene versus 3,3',5,5'-tetra-tert-butyl-azobenzene (TBA) at Au(111): characterizing the role of spacer groups.

Science.gov (United States)

McNellis, Erik R; Bronner, Christopher; Meyer, Jörg; Weinelt, Martin; Tegeder, Petra; Reuter, Karsten

2010-06-28

We present large-scale density-functional theory (DFT) calculations and temperature programmed desorption measurements to characterize the structural, energetic and vibrational properties of the functionalized molecular switch 3,3',5,5'-tetra-tert-butyl-azobenzene (TBA) adsorbed at Au(111). Particular emphasis is placed on exploring the accuracy of the semi-empirical dispersion correction approach to semi-local DFT (DFT-D) in accounting for the substantial van der Waals component in the surface bonding. In line with previous findings for benzene and pure azobenzene at coinage metal surfaces, DFT-D significantly overbinds the molecule, but seems to yield an accurate adsorption geometry as far as can be judged from the experimental data. Comparing the trans adsorption geometry of TBA and azobenzene at Au(111) reveals a remarkable insensitivity of the structural and vibrational properties of the -N[double bond, length as m-dash]N- moiety. This questions the established view of the role of the bulky tert-butyl-spacer groups for the switching of TBA in terms of a mere geometric decoupling of the photochemically active diazo-bridge from the gold substrate.

Dynamics in miscible blends of polyisoprene and poly(p-tert-butyl styrene): thermo–rheological behavior of components

OpenAIRE

Chen, Quan; Matsumiya, Yumi; Watanabe, Hiroshi

2011-01-01

For miscible blends of moderately entangled cis-polyisoprene (PI) and poly(p-tert-butyl styrene) (PtBS), viscoelastic and dielectric properties were examined over a wide range of temperature (T) to discuss the thermo–rheological behavior of respective components. Because PI has the type-A dipole, whereas PtBS does not, the slow dielectric response of the blends was exclusively attributed to the global motion of the PI chains therein. In most of the blends examined, the viscoelastic relaxation...

Thermochemical studies of 4-tert-butylbiphenyl and 4,4'-di-tert-butylbiphenyl

International Nuclear Information System (INIS)

Melkhanova, Svetlana V.; Pimenova, Svetlana M.; Chelovskaya, Nelly V.; Miroshnichenko, Eugenii A.; Pashchenko, Larisa L.; Nesterov, Igor A.; Naumkin, P.V.

2009-01-01

The standard massic energies of compounds of 4-tert-butylbiphenyl and 4,4'-di-tert-butylbiphenyl were measured at T = 298.15 K by static-bomb combustion calorimetry. The standard enthalpies of vaporization, fusion and sublimation were measured in a Calvet microcalorimeter, or by differential scanning calorimetry. The standard molar enthalpies of formation in the condensed and gaseous states were obtained from these data. The tert-butyl group increments for the substitution of one hydrogen atom in a position '4' in biphenyl molecule were calculated

A novel imidazopyridine derivative, X22, prevents the retinal ischemia-reperfusion injury via inhibition of MAPKs.

Science.gov (United States)

Bian, Yang; Ren, Luqing; Wang, Lei; Xu, Shanmei; Tao, Jianjian; Zhang, Xiuhua; Huang, Yi; Qian, Yuanyuan; Zhang, Xin; Song, Zongming; Wu, Wencan; Wang, Yi; Liang, Guang

2015-06-01

Inflammation is a pathological hallmark of ischemia reperfusion (I/R) injury. The present study was conducted to explore the ability of a new anti-inflammatory compound, X22, to attenuate retinal I/R injury via cytokine-inhibitory mechanism. For the in vitro experiment, ARPE-19 cells were pretreated with X22 (5 or 10 μM) or saline for 2 h, followed by stimulation with tert-butyl hydroperoxide (TBHP, 1000 μM) for an indicated amount of time. The expression of inflammatory mediators, cell viability, and cell apoptosis were evaluated. For the in vivo experiment, the rats were randomized to receive treatment with saline or X22 (0.1 μM/kg, 3 μL) before the induction of I/R injury. Histological evaluation, apoptosis of retinal cells, macrophage infiltration, and retina functional changes were further determined. Our data showed that pretreatment with X22 significantly inhibited TBHP-induced inflammatory cytokine expression in ARPE-19 cells. The anti-inflammatory activity of X22 may be associated with its inhibition on MAPKs, rather than NF-κB. Subsequently, our data proved that TBHP induced apoptosis in ARPE-19 cells, while pretreatment of X22 significantly suppressed TBHP-caused ARPE-19 apoptosis. Finally, the in vivo data revealed that X22 administration maintained better inner retinal layer structures, reduced apoptosis of retinal ganglion cell, and improved retinal function in retinal I/R rat models, which were accompanied with a remarkable decrease in retinal macrophage infiltration. These results suggest that the novel compound X22 is a potential agent for the treatment of retinal I/R-related diseases via the MAPKs-targeting anti-inflammatory mechanism and deserves the further development. Copyright © 2015 Elsevier Ltd. All rights reserved.

Tailored Interfaces for Biosensors and Cell-Surface Interaction Studies via Activation and Derivatization of Polystyrene-block-poly(tert-butyl acrylate) Thin Films

NARCIS (Netherlands)

Feng, C.L.; Embrechts, A.; Bredebusch, Ilona; Bouma, Anita; Schnekenburger, Jürgen; Garcia Parajo, M.F.; Domschke, Wolfram; Vancso, Gyula J.; Schönherr, Holger

2007-01-01

Thin spin-coated films of polystyrene-block-poly(tert-butyl acrylate) (PS690-b-PtBA1210) on various substrates are introduced as versatile, robust reactive platform for the immobilization of (bio)molecules for the fabrication of tailored biointerfaces. The films are characterized by high stability

Structure of the mercury(II mixed-halide (Br/Cl complex of 2,2′-(5-tert-butyl-1,3-phenylenebis(1-pentyl-1H-benzo[d]imidazole

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Varsha Rani

2017-03-01

Full Text Available The mercury(II complex of 2,2′-(5-tert-butyl-1,3-phenylenebis(1-pentyl-1H-benzimidazole, namely catena-poly[[dihalogenidomercury(II]-μ-2,2′-(5-tert-butyl-1,3-phenylenebis(1-pentyl-1H-benzimidazole-κ2N3:N3′], [HgBr1.52Cl0.48(C34H42N4], 2, has a polymeric structure bridging via the N atoms from the benzimidazole moieties of the ligand. The compound crystallizes in the orthorhombic space group Pca21 and is a racemic twin [BASF = 0.402 (9]. The geometry around the HgII atom is distorted tetrahedral, with the HgII atom coordinated to two N atoms, one Br atom, and a fourth coordination site is occupied by a mixed halide (Br/Cl. For the two ligands in the asymmetric unit, there is disorder with one of the two tert-butyl groups and benzimidazole moieties showing twofold disorder, with occupancy factors of 0.57 (2:0.43 (2 for the tert-butyl group and 0.73 (3:0.27 (3 for the benzimidazole group. In addition, there is threefold disorder for two of the four n-pentyl groups, with occupancy factors of 0.669 (4:0.177 (4:0.154 (4 and 0.662 (4:0.224 (4:0.154 (4, respectively. The molecules form a one-dimensional helical polymer propagating in the b-axis direction. The helices are held together by intra-strand C—H...Br and C—H...Cl interactions. Each strand is further linked by inter-strand C—H...Br and C—H...Cl interactions. In addition, there are weak C—H...N inter-strand interactions which further stabilize the structural arrangement.

6,6'-(1E,1'E-((1R,2R-1,2-Diphenylethane-1,2-diylbis(azan-1-yl-1-ylidenebis(methan-1-yl-1-ylidenebis(2-tert-butyl-4-((trimethylsilylethynylphenol

Directory of Open Access Journals (Sweden)

David Díaz Díaz

2013-03-01

Full Text Available Functionalizable salen derivative, 6,6'-(1E,1'E-((1R,2R-1,2-diphenylethane-1,2-diylbis(azan-1-yl-1-ylidenebis(methan-1-yl-1-ylidenebis(2-tert-butyl-4-((trimethylsilyl ethyn-ylphenol (3, was synthesized by condensation between (1R,2R-1,2-diphenylethane-1,2-diamine (2 and 3-tert-butyl-2-hydroxy-5-((trimethylsilylethynyl benzaldehyde (1 under refluxing conditions. The title compound was characterized by 1H-NMR, 13C-NMR, FT-IR, high-resolution mass spectrometry, optical rotation and melting point determination.

Detection and Quantification of Methyl tert-Butyl Ether-Degrading Strain PM1 by Real-Time TaqMan PCR

OpenAIRE

Hristova, Krassimira R.; Lutenegger, Christian M.; Scow, Kate M.

2001-01-01

The fuel oxygenate methyl tert-butyl ether (MTBE), a widely distributed groundwater contaminant, shows potential for treatment by in situ bioremediation. The bacterial strain PM1 rapidly mineralizes and grows on MTBE in laboratory cultures and can degrade the contaminant when inoculated into groundwater or soil microcosms. We applied the TaqMan quantitative PCR method to detect and quantify strain PM1 in laboratory and field samples. Specific primers and probes were designed for the 16S ribos...

A Suppressor of the Menadione-Hypersensitive Phenotype of a Xanthomonas campestris pv. phaseoli oxyR Mutant Reveals a Novel Mechanism of Toxicity and the Protective Role of Alkyl Hydroperoxide Reductase

Science.gov (United States)

Vattanaviboon, Paiboon; Whangsuk, Wirongrong; Mongkolsuk, Skorn

2003-01-01

We isolated menadione-resistant mutants of Xanthomonas campestris pv. phaseoli oxyR (oxyRXp). The oxyRR2Xp mutant was hyperresistant to the superoxide generators menadione and plumbagin and was moderately resistant to H2O2 and tert-butyl hydroperoxide. Analysis of enzymes involved in oxidative-stress protection in the oxyRR2Xp mutant revealed a >10-fold increase in AhpC and AhpF levels, while the levels of superoxide dismutase (SOD), catalase, and the organic hydroperoxide resistance protein (Ohr) were not significantly altered. Inactivation of ahpC in the oxyRR2Xp mutant resulted in increased sensitivity to menadione killing. Moreover, high levels of expression of cloned ahpC and ahpF in the oxyRXp mutant complemented the menadione hypersensitivity phenotype. High levels of other oxidant-scavenging enzymes such as catalase and SOD did not protect the cells from menadione toxicity. These data strongly suggest that the toxicity of superoxide generators could be mediated via organic peroxide production and that alkyl hydroperoxide reductase has an important novel function in the protection against the toxicity of these compounds in X. campestris. PMID:12591894

Thermochemical studies of 4-tert-butylbiphenyl and 4,4'-di-tert-butylbiphenyl

Energy Technology Data Exchange (ETDEWEB)

Melkhanova, Svetlana V. [Chemistry Department, Moscow State University, Leninskie Gory 1, Bl.3, Moscow 119992 (Russian Federation)], E-mail: melkhan@phys.chem.msu.ru; Pimenova, Svetlana M.; Chelovskaya, Nelly V. [Chemistry Department, Moscow State University, Leninskie Gory 1, Bl.3, Moscow 119992 (Russian Federation); Miroshnichenko, Eugenii A. [Institute of Chemical Physics RAS, Kosygina 4, Moscow 117977 (Russian Federation); Pashchenko, Larisa L. [Chemistry Department, Moscow State University, Leninskie Gory 1, Bl.3, Moscow 119992 (Russian Federation); Institute of Chemical Physics RAS, Kosygina 4, Moscow 117977 (Russian Federation); Nesterov, Igor A.; Naumkin, P.V. [Samara State Technical University, Galaktionovskaya 141, Samara 443010 (Russian Federation)

2009-05-15

The standard massic energies of compounds of 4-tert-butylbiphenyl and 4,4'-di-tert-butylbiphenyl were measured at T = 298.15 K by static-bomb combustion calorimetry. The standard enthalpies of vaporization, fusion and sublimation were measured in a Calvet microcalorimeter, or by differential scanning calorimetry. The standard molar enthalpies of formation in the condensed and gaseous states were obtained from these data. The tert-butyl group increments for the substitution of one hydrogen atom in a position '4' in biphenyl molecule were calculated.

Effects of the Macular Carotenoid Lutein in Human Retinal Pigment Epithelial Cells

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Xiaoming Gong

2017-12-01

Full Text Available Retinal pigment epithelial (RPE cells are central to retinal health and homoeostasis. Oxidative stress-induced damage to the RPE occurs as part of the pathogenesis of age-related macular degeneration and neovascular retinopathies (e.g., retinopathy of prematurity, diabetic retinopathy. The xanthophyll carotenoids, lutein and zeaxanthin, are selectively taken up by the RPE, preferentially accumulated in the human macula, and transferred to photoreceptors. These macular xanthophylls protect the macula (and the broader retina via their antioxidant and photo-protective activities. This study was designed to investigate effects of various carotenoids (β-carotene, lycopene, and lutein on RPE cells subjected to either hypoxia or oxidative stress, in order to determine if there is effect specificity for macular pigment carotenoids. Using human RPE-derived ARPE-19 cells as an in vitro model, we exposed RPE cells to various concentrations of the specific carotenoids, followed by either graded hypoxia or oxidative stress using tert-butyl hydroperoxide (tBHP. The results indicate that lutein and lycopene, but not β-carotene, inhibit cell growth in undifferentiated ARPE-19 cells. Moreover, cell viability was decreased under hypoxic conditions. Pre-incubation of ARPE-19 cells with lutein or lycopene protected against tBHP-induced cell loss and cell co-exposure of lutein or lycopene with tBHP essentially neutralized tBHP-dependent cell death at tBHP concentrations up to 500 μM. Our findings indicate that lutein and lycopene inhibit the growth of human RPE cells and protect the RPE against oxidative stress-induced cell loss. These findings contribute to the understanding of the protective mechanisms attributable to retinal xanthophylls in eye health and retinopathies.

Study of an aquifer contaminated by ethyl tert-butyl ether (ETBE): Site characterization and on-site bioremediation

International Nuclear Information System (INIS)

Fayolle-Guichard, Françoise; Durand, Jonathan; Cheucle, Mathilde; Rosell, Mònica; Michelland, Rory Julien; Tracol, Jean-Philippe; Le Roux, Françoise; Grundman, Geneviève; Atteia, Olivier; Richnow, Hans H.; Dumestre, Alain

2012-01-01

Highlights: ► Ethyl tert-butyl ether (ETBE) (>300 mg L −1 ) found in a groundwater (gas-station). ► No significant carbon or hydrogen isotopic fractionation of ETBE along the plume. ► MC-IFP culture degraded ETBE (0.91 mg L −1 h −1 ) and BTEX (0.64 mg L −1 h −1 ). ► A pilot plant (2 m 3 ) inoculated with MC-IFP degraded ETBE in groundwater (15 °C). ► ethB gene (ETBE biodegradation) amplified during bioaugmentation (5 × 10 6 ethB gene copies L −1 ). - Abstract: Ethyl tert-butyl ether (ETBE) was detected at high concentration (300 mg L −1 ) in the groundwater below a gas-station. No significant carbon neither hydrogen isotopic fractionation of ETBE was detected along the plume. ETBE and BTEX biodegradation capacities of the indigenous microflora Pz1-ETBE and of a culture (MC-IFP) composed of Rhodococcus wratislaviensis IFP 2016, Rhodococcus aetherivorans IFP 2017 and Aquincola tertiaricarbonis IFP 2003 showed that ETBE and BTEX degradation rates were in the same range (ETBE: 0.91 and 0.83 mg L −1 h −1 and BTEX: 0.64 and 0.82 mg L −1 h −1 , respectively) but tert-butanol (TBA) accumulated transiently at a high level using Pz1-ETBE (74 mg L −1 ). An on-site pilot plant (2 m 3 ) filled with polluted groundwater and inoculated by MC-IFP, successfully degraded four successive additions of ETBE and gasoline. However, an insignificant ETBE isotopic fractionation was also accompanying this decrease which suggested the involvement of low fractionating-strains using EthB enzymes, but required of additional proofs. The ethB gene encoding a cytochrome P450 involved in ETBE biodegradation (present in R. aetherivorans IFP 2017) was monitored by quantitative real-time polymerase chain reaction (q-PCR) on DNA extracted from water sampled in the pilot plant which yield up to 5 × 10 6 copies of ethB gene per L −1 .

Metabolism of tert-butylhydroquinone to S-substituted conjugates in the male fischer 344 rat

NARCIS (Netherlands)

Peters, M.M.C.G.; Lau, S.S.; Dulik, D.; Murphy, D.; Ommen, B. van; Bladeren, P.J. van; Monks, T.J.

1996-01-01

tert-Butyl-4-hydroxyanisole (BHA) and its demethylated analog, tert- butyl-hydroquinone (TBHQ), are antioxidants used in food. Both BHA and TBHQ have been shown to promote kidney and bladder carcinogenesis in the rat. We have previously demonstrated that glutathione (GSH) conjugates of a variety of

Synthesis of [[sup 123]I]tert-Butyl 8-iodo-5,6-dihydro-5-methyl-6-oxo-4H-imidazo[1,5-a][1,4]benzodiaze pine 3-carboxylate, a potential SPECT imaging agent for diazepam-intensive (DI) benzodiazepine receptors

Energy Technology Data Exchange (ETDEWEB)

He, Xiaoshu; Matecka, Dorota; Gu, Ziqiang; Rice, K C; Costa, B.R. de [National Inst. of Diabetes and Digestive and Kidney Diseases, Bethesda, MD (United States); Lee, K S [National Inst. of Mental Health, Washington, DC (United States); Wong, Garry; Skolnick, Phil [National Inst. of Diabetes and Digestive and Kidney Diseases, Bethesda, MD (United States). Lab. of Neuroscience

1994-01-01

[[sup 123]I]tert-Butyl 8-iodo-5,6-dihydro-5-methyl-6-oxo-4H-imidazo [1,5-a] [1,4]benzodiazepine 3-carboxylate ([[sup 123]I]3), a high affinity and selective radioligand for the diazepam insensitive (DI) benzodiazepine receptor was synthesized in 2 steps from tert-butyl 8-bromo-5,6-dihydro-5-methyl-6-oxo-4H-imidazo[1,5-a][1,4]benzodiaz epine 3-carboxylate. (Author).

Aerobic methylcyclohexane-promoted epoxidation of stilbene over gold nanoparticles supported on Gd-doped titania

KAUST Repository

Mendez, Violaine; Guillois, Kevin; Daniè le, Sté phane; Tuel, Alain; Caps, Valerie

2010-01-01

Aerobic partial oxidations of alkanes and alkenes are important processes of the petrochemical industry. The radical mechanisms involved can be catalyzed by soluble salts of transition metals (Co, Cu, Mn...). We show here that the model methylcyclohexane/stilbene co-oxidation reaction can be efficiently catalyzed at lower temperature by supported gold nanoparticles. The support has little influence on gold intrinsic activity but more on the apparent reaction rates which are a combination of catalytic activity and diffusion limitations. These are here minimized by using gadolinium-doped titania nanocrystallites as support for gold nanoparticles. This material is obtained by mild hydrolysis of a new Gd4TiO(OiPr)14 bimetallic oxoalkoxide. It leads to enhanced wettability of the < 3 nm gold particles in the tert-butyl hydroperoxide (TBHP)-initiated epoxidation of stilbene in methylcyclohexane; Au/TiO2:Gd3+ is in turn as active as the state-of-the-art hydrophobic Au/SiO2 catalyst. The rate-determining step of this reaction is identified as the gold-catalyzed homolytic decomposition of TBHP generating radicals and initiating the methylcyclohexane-mediated epoxidation of stilbene, yielding a methylcyclohexan-1-ol/trans-stilbene oxide mixture. Methylcyclohexan-1-ol can also be obtained in the absence of the alkene in the gold-catalyzed solvent-free autoxidation of methylcyclohexane, evidencing the catalytic potential of gold nanoparticles for low temperature C-H activation. © 2010 The Royal Society of Chemistry.

Butylated caffeic acid: An efficient novel antioxidant

Directory of Open Access Journals (Sweden)

G. Shi

2017-09-01

Full Text Available A novel antioxidant, butylated caffeic acid (BCA was rationally designed by adding a tert-butyl group to caffeic acid, which was synthesized at a high yield (36.2% from 2-methoxy-4-methylphenol by a four-step reaction including Friedel-Crafts alkylation, bromine oxidation, ether bond hydrolysis and Knoevenagel condensation. Its antioxidant capacity was much stronger than common commercial antioxidant tert-butyl hydroquinone (TBHQ and its mother compound, caffeic acid, in both rancimat and deep frying tests. When investigated via the DPPH method, the antioxidant capacity of BCA was almost equal to TBHQ, but lower than caffeic acid. BCA could be a potentially strong antioxidant, especially for food processing at high temperatures such as deep frying and baking.

Butylated caffeic acid: An efficient novel antioxidant

International Nuclear Information System (INIS)

Shi, G.; Liao, X.; Olajide, T.M.; Liu, J.; Jiang, X.; Weng, X.

2017-01-01

A novel antioxidant, butylated caffeic acid (BCA) was rationally designed by adding a tert-butyl group to caffeic acid, which was synthesized at a high yield (36.2%) from 2-methoxy-4-methylphenol (1) by a four-step reaction including Friedel-Crafts alkylation, bromine oxidation, ether bond hydrolysis and Knoevenagel condensation. Its antioxidant capacity was much stronger than common commercial antioxidant tert-butyl hydroquinone (TBHQ) and its mother compound, caffeic acid, in both rancimat and deep frying tests. When investigated via the DPPH method, the antioxidant capacity of BCA was almost equal to TBHQ, but lower than caffeic acid. BCA could be a potentially strong antioxidant, especially for food processing at high temperatures such as deep frying and baking. [es

Influence of mass transport towards deactivation in tert-butyl-source driven isobutane/2-butene alkylation

Energy Technology Data Exchange (ETDEWEB)

Aschauer, S.J.; Jess, A. [Bayreuth Univ. (Germany). Dept. of Chemical Engineering

2011-07-01

The deactivation of i-butane/trans-2-butene alkylation using tert-butyl-halide promoted ionic liquid catalysts is studied.Here, the mass transport was modified by varying the feed rate and the type of promoter addition. The experimental data show that the deactivation increases with increasing feed rate. Moreover, a biliquid foam is formed when feed rates above 1 g/min are adjusted. As the results indicate a strong influence of the biliquid foam and its formation on deactivation, both aspects are also discussed.When the promoter is added to the feed mixture an increase of conversion with time on stream is observed. A deactivation in continuous promoter addition mode could not be noted in the investigated time-on-stream range. (orig.)

Determination of Methyl tert-Butyl Ether and tert-Butyl Alcohol in Water by Solid-Phase Microextraction/Head Space Analysis in Comparison to EPA Method 5030/8260B

Energy Technology Data Exchange (ETDEWEB)

Oh, Keun-Chan; Stringfellow, William T.

2003-10-02

Methyl tert-butyl ether (MTBE) is now one of the most common groundwater contaminants in the United States. Groundwater contaminated with MTBE is also likely to be contaminated with tert-butyl alcohol (TBA), because TBA is a component of commercial grade MTBE, TBA can also be used as a fuel oxygenate, and TBA is a biodegradation product of MTBE. In California, MTBE is subject to reporting at concentrations greater than 3 {micro}g/L. TBA is classified as a ''contaminant of current interest'' and has a drinking water action level of 12 {micro}g/L. In this paper, we describe the development and optimization of a simple, automated solid phase microextraction (SPME) method for the analysis of MTBE and TBA in water and demonstrate the applicability of this method for monitoring MTBE and TBA contamination in groundwater, drinking water, and surface water. In this method, the headspace (HS) of a water sample is extracted with a carboxen/polydimethylsiloxane SPME fiber, the MTBE and TBA are desorbed into a gas chromatograph (GC), and detected using mass spectrometry (MS). The method is optimized for the routine analysis of MTBE and TBA with a level of quantitation of 0.3 {micro}g/L and 4 {micro}g/L, respectively, in water. MTBE quantitation was linear for over two orders of concentration (0.3 {micro}g/L -80 {micro}g/L). TBA was found to be linear within the range of 4 {micro}g/L-7,900 {micro}g/L. The lower level of detection for MTBE is 0.03 {micro}g/L using this method. This SPME method using headspace extraction was found to be advantageous over SPME methods requiring immersion of the fiber into the water samples, because it prolonged the life of the fiber by up to 400 sample analyses. This is the first time headspace extraction SPME has been shown to be applicable to the measurement of both MTBE and TBA at concentrations below regulatory action levels. This method was compared with the certified EPA Method 5030/8260B (purge-and-trap/GC/MS) using split

Synthetic phenolic antioxidants, including butylated hydroxytoluene (BHT), in resin-based dental sealants

Energy Technology Data Exchange (ETDEWEB)

Wang, Wei; Kannan, Pranav; Xue, Jingchuan [Wadsworth Center, New York State Department of Health, and Department of Environmental Health Sciences, School of Public Health, State University of New York at Albany, Empire State Plaza, P.O. Box 509, Albany, NY 12201-0509 (United States); Kannan, Kurunthachalam, E-mail: Kurunthachalam.kannan@health.ny.gov [Wadsworth Center, New York State Department of Health, and Department of Environmental Health Sciences, School of Public Health, State University of New York at Albany, Empire State Plaza, P.O. Box 509, Albany, NY 12201-0509 (United States); Biochemistry Department, Faculty of Science, Experimental Biochemistry Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah (Saudi Arabia)

2016-11-15

Resin-based dental sealants (also referred to as pit-and-fissure sealants) have been studied for their contribution to bisphenol A (BPA) exposure in children. Nevertheless, little attention has been paid to the occurrence of other potentially toxic chemicals in dental sealants. In this study, the occurrence of six synthetic phenolic antioxidants (SPAs), including 2,6-di-tert-butyl-4-hydroxytoluene (BHT), 2,6-di-tert-butyl-4-(hydroxyethyl)phenol (BHT-OH), 3,5-di-tert-butyl-4-hydroxy-benzaldehyde (BHT-CHO), 2,6-di-tert-butylcyclohexa-2,5-diene-1,4-dione (BHT-Q), 3,5-di-tert-butyl-4-hydroxybenzoic acid (BHT-COOH) and 2-tert-butyl-4-methoxyphenol (BHA), was examined in 63 dental sealant products purchased from the U.S. market. BHT was found in all dental sealants at median and maximum concentrations of 56.8 and 1020 µg/g, respectively. The metabolites of BHT and BHA were detected in 39–67% of samples, at concentration ranges of tert-butyl-4-hydroxytoluene (BHT) concentration of up to 1020 µg/g was found. • Estimated daily intake of BHT after sealant placement was up to 9.52 µg/kg bw/d. • Daily intake of BHT through dental sealant application was below the acceptable daily intake.

Synthetic phenolic antioxidants, including butylated hydroxytoluene (BHT), in resin-based dental sealants

International Nuclear Information System (INIS)

Wang, Wei; Kannan, Pranav; Xue, Jingchuan; Kannan, Kurunthachalam

2016-01-01

Resin-based dental sealants (also referred to as pit-and-fissure sealants) have been studied for their contribution to bisphenol A (BPA) exposure in children. Nevertheless, little attention has been paid to the occurrence of other potentially toxic chemicals in dental sealants. In this study, the occurrence of six synthetic phenolic antioxidants (SPAs), including 2,6-di-tert-butyl-4-hydroxytoluene (BHT), 2,6-di-tert-butyl-4-(hydroxyethyl)phenol (BHT-OH), 3,5-di-tert-butyl-4-hydroxy-benzaldehyde (BHT-CHO), 2,6-di-tert-butylcyclohexa-2,5-diene-1,4-dione (BHT-Q), 3,5-di-tert-butyl-4-hydroxybenzoic acid (BHT-COOH) and 2-tert-butyl-4-methoxyphenol (BHA), was examined in 63 dental sealant products purchased from the U.S. market. BHT was found in all dental sealants at median and maximum concentrations of 56.8 and 1020 µg/g, respectively. The metabolites of BHT and BHA were detected in 39–67% of samples, at concentration ranges of tert-butyl-4-hydroxytoluene (BHT) concentration of up to 1020 µg/g was found. • Estimated daily intake of BHT after sealant placement was up to 9.52 µg/kg bw/d. • Daily intake of BHT through dental sealant application was below the acceptable daily intake.

Aerobic biodegradation of tert-butyl alcohol (TBA) by psychro- and thermo-tolerant cultures derived from granular activated carbon (GAC).

Science.gov (United States)

Reinauer, Kimberly M; Zhang, Yang; Yang, Xiaomin; Finneran, Kevin T

2008-04-01

Tert-butyl alcohol (TBA) is a metabolite of methyl tert-butyl ether and is itself possibly a fuel oxygenate. The goals of this study were to enrich and characterize TBA-degrading micro-organism(s) from a granular activated carbon (GAC) unit currently treating TBA. The results reported herein describe the first aerobic, TBA-degrading cultures derived from GAC. Strains KR1 and YZ1 were enriched from a GAC sample in a bicarbonate-buffered freshwater medium. TBA was degraded to 10% of the initial concentration (2-5 mM) within 5 days after initial inoculation and was continuously degraded within 1 day of each re-amendment. Resting cell suspensions mineralized 70 and 60% of the TBA within 24 h for KR1 and YZ1, respectively. Performance optimization with resting cells was conducted to investigate kinetics and the extent of TBA degradation as influenced by oxygen, pH and temperature. The most favorable temperature was 37 degrees C; however, TBA was degraded from 4 to 60 degrees C, indicating that the culture will sufficiently treat groundwater without heating. This is also the first report of psychrotolerant or thermotolerant TBA biodegradation. The pH range for TBA degradation ran from 5.0 to 9.0. Phylogenetic data using a partial 16S rRNA gene sequence (570 bases) suggest that the primary members of KR1 and YZ1 include uncharacterized organisms within the genera Hydrogenophaga, Caulobacter, and Pannonibacter.

Assessment of genotoxicity of methyl-tert-butyl ether, benzene, toluene, ethylbenzene, and xylene to human lymphocytes using comet assay

International Nuclear Information System (INIS)

Chen, Colin S.; Hseu, You C.; Liang, Shih H.; Kuo, J.-Y.; Chen, Ssu. C.

2008-01-01

Methyl-tert-butyl ether (MTBE) is a gasoline oxygenate and antiknock additive substituting for lead alkyls currently in use worldwide. Benzene, toluene, ethylbenzene, and xylene (BTEX) are volatile monoaromatic hydrocarbons which are commonly found together in crude petroleum and petroleum products such as gasoline. The aim of this study is to evaluate the genotoxic effects of these tested chemicals in human lymphocytes. Using the alkaline comet assay, we showed that all of the tested chemicals induce DNA damage in isolated human lymphocytes. This effect could follow from the induction of DNA strands breaks. The neutral version of the test revealed that MTBE, benzene, and xylenes induce DNA double-strand breaks at 200 μM. Apart from MTBE, the spin traps, 5,5-dimethyl-pyrroline-N-oxide (DMPO) and N-tert-butyl-α-phenylnitrone (PBN) can decrease the level of DNA damage in BTEX at 200 μM. This indicated that DNA damage could result from the participation of free radicals in DNA-damaging effect, which was further supported by the fact that post-treatment of formamidopyrimidine-DNA glycosylase (Fpg), enzyme recognizing oxidized DNA purines, gave rise to a significant increase in the extent of DNA damage in cells treated with benzene, and xylene at 200 μM. The results obtained suggested that MTBE and BTEX could induce a variety type of DNA damage such as single-strand breaks (SSBs), double-strand breaks (DSBs), and oxidative base modification

Calculation of carbon-14, chlorine-37, and deuterium kinetic isotope effects in the solvolysis of tert-butyl chloride

International Nuclear Information System (INIS)

Burton, G.W.; Sims, L.B.; Wilson, J.C.; Fry, A.

1977-01-01

In the solvolysis of tert-butyl chloride, satisfactory α-carbon-14, β-deuterium, and chlorine kinetic isotope effects (KIE) may be calculated for a productlike transition state characterized by bond orders n/sub C Cl/ = 0.2, n/sub C C/ = 1.18, and n/sub C H/ = 0.94, employing a diagonal valence force field, provided that allowance is made for hydrogen-bonded solvation of the developing chloride ion with n/sub Cl H/ approx. 0.05 (approx. 7 kcal/mole hydrogen bonds). The effect of the three solvating molecules appears to be to increase the ''effective'' mass of the incipient chloride ion and to decrease the loss of zero-point energy in going to the transition state. Reaction coordinates more complicated than a simple heterolysis of the carbon-chlorine bond appear to be unnecessary and there is no advantage in employing force fields more complex than a simple valence force field containing only diagonal elements for both the reactant and the transition state model. The structural and bonding features of the proposed transition state are in accord with earlier more qualitative conclusions concerning the polar nature and productlike character of the transition state, and provide a reasonable explanation of the kinetic and equilibrium isotope effects (EIE) for the reaction. An alternative transition state model involving weak solvent nucleophilic assistance provides reasonable calculated values for the KIE, but the EIE strongly suggest the importance of solvation of the leaving group which, together with the hyperconjugation of the β hydrogens, provides a preferred explanation of the tert-butyl solvolysis results

3,3′-Di-tert-butyl-1,1′-[1,3-phenylenebis(methylene]diurea

Directory of Open Access Journals (Sweden)

Md. Alamgir Hossain

2010-03-01

Full Text Available The title compound, C18H30N4O2, contains two tert-butyl urea groups, each connected to a benzene ring though a methylene group. One of the groups occupies a position almost normal to the aromatic plane with a C—N—C—C torsion angle of −94.4 (4°, while the other is considerably twisted from the ring with a C—N—C—C torsion angle of −136.1 (4°. In the crystal, pairs of molecules are connected to each other, forming centrosymmetric dimers in which two NH groups of one molecule act as hydrogen-bond donors to one carbonyl O atom of the other molecule. The dimers are linked into sheets parallel to (100 by N—H...O hydrogen bonds involving the remaining N—H and C=O groups.

Study of an aquifer contaminated by ethyl tert-butyl ether (ETBE): Site characterization and on-site bioremediation

Energy Technology Data Exchange (ETDEWEB)

Fayolle-Guichard, Francoise, E-mail: francoise.fayolle@ifpen.fr [IFP Energies nouvelles, 1 et 4 avenue de Bois-Preau, 92852 Rueil-Malmaison (France); Durand, Jonathan [Institut EGID Bordeaux 3, 1 Allee Daguin 33607 Pessac Cedex (France); SERPOL, 2 chemin du Genie, BP 80, 69633 Venissieux Cedex (France); Cheucle, Mathilde [SERPOL, 2 chemin du Genie, BP 80, 69633 Venissieux Cedex (France); Rosell, Monica [Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, 04318 Leipzig (Germany); Michelland, Rory Julien [Universite de Lyon, F-69622 Lyon (France); Universite Lyon 1, Villeurbanne (France); CNRS, UMR5557, Ecologie Microbienne (France); Tracol, Jean-Philippe [SERPOL, 2 chemin du Genie, BP 80, 69633 Venissieux Cedex (France); Le Roux, Francoise [IFP Energies nouvelles, 1 et 4 avenue de Bois-Preau, 92852 Rueil-Malmaison (France); Grundman, Genevieve [Universite de Lyon, F-69622 Lyon (France); Universite Lyon 1, Villeurbanne (France); CNRS, UMR5557, Ecologie Microbienne (France); Atteia, Olivier [Institut EGID Bordeaux 3, 1 Allee Daguin 33607 Pessac Cedex (France); Richnow, Hans H. [Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, 04318 Leipzig (Germany); Dumestre, Alain [SERPOL, 2 chemin du Genie, BP 80, 69633 Venissieux Cedex (France); and others

2012-01-30

Highlights: Black-Right-Pointing-Pointer Ethyl tert-butyl ether (ETBE) (>300 mg L{sup -1}) found in a groundwater (gas-station). Black-Right-Pointing-Pointer No significant carbon or hydrogen isotopic fractionation of ETBE along the plume. Black-Right-Pointing-Pointer MC-IFP culture degraded ETBE (0.91 mg L{sup -1} h{sup -1}) and BTEX (0.64 mg L{sup -1} h{sup -1}). Black-Right-Pointing-Pointer A pilot plant (2 m{sup 3}) inoculated with MC-IFP degraded ETBE in groundwater (15 Degree-Sign C). Black-Right-Pointing-Pointer ethB gene (ETBE biodegradation) amplified during bioaugmentation (5 Multiplication-Sign 10{sup 6}ethB gene copies L{sup -1}). - Abstract: Ethyl tert-butyl ether (ETBE) was detected at high concentration (300 mg L{sup -1}) in the groundwater below a gas-station. No significant carbon neither hydrogen isotopic fractionation of ETBE was detected along the plume. ETBE and BTEX biodegradation capacities of the indigenous microflora Pz1-ETBE and of a culture (MC-IFP) composed of Rhodococcus wratislaviensis IFP 2016, Rhodococcus aetherivorans IFP 2017 and Aquincola tertiaricarbonis IFP 2003 showed that ETBE and BTEX degradation rates were in the same range (ETBE: 0.91 and 0.83 mg L{sup -1} h{sup -1} and BTEX: 0.64 and 0.82 mg L{sup -1} h{sup -1}, respectively) but tert-butanol (TBA) accumulated transiently at a high level using Pz1-ETBE (74 mg L{sup -1}). An on-site pilot plant (2 m{sup 3}) filled with polluted groundwater and inoculated by MC-IFP, successfully degraded four successive additions of ETBE and gasoline. However, an insignificant ETBE isotopic fractionation was also accompanying this decrease which suggested the involvement of low fractionating-strains using EthB enzymes, but required of additional proofs. The ethB gene encoding a cytochrome P450 involved in ETBE biodegradation (present in R. aetherivorans IFP 2017) was monitored by quantitative real-time polymerase chain reaction (q-PCR) on DNA extracted from water sampled in the pilot plant

Effect of benzene and ethylbenzene on the transcription of methyl-tert-butyl ether degradation genes of Methylibium petroleiphilum PM1.

Science.gov (United States)

Joshi, Geetika; Schmidt, Radomir; Scow, Kate M; Denison, Michael S; Hristova, Krassimira R

2016-09-01

Methyl-tert-butyl ether (MTBE) and its degradation by-product, tert-butyl alcohol (TBA), are widespread contaminants detected frequently in groundwater in California. Since MTBE was used as a fuel oxygenate for almost two decades, leaking underground fuel storage tanks are an important source of contamination. Gasoline components such as BTEX (benzene, toluene, ethylbenzene and xylenes) are often present in mixtures with MTBE and TBA. Investigations of interactions between BTEX and MTBE degradation have not yielded consistent trends, and the molecular mechanisms of BTEX compounds' impact on MTBE degradation are not well understood. We investigated trends in transcription of biodegradation genes in the MTBE-degrading bacterium, Methylibium petroleiphilum PM1 upon exposure to MTBE, TBA, ethylbenzene and benzene as individual compounds or in mixtures. We designed real-time quantitative PCR assays to target functional genes of strain PM1 and provide evidence for induction of genes mdpA (MTBE monooxygenase), mdpJ (TBA hydroxylase) and bmoA (benzene monooxygenase) in response to MTBE, TBA and benzene, respectively. Delayed induction of mdpA and mdpJ transcription occurred with mixtures of benzene and MTBE or TBA, respectively. bmoA transcription was similar in the presence of MTBE or TBA with benzene as in their absence. Our results also indicate that ethylbenzene, previously proposed as an inhibitor of MTBE degradation in some bacteria, inhibits transcription of mdpA, mdpJ and bmoAgenes in strain PM1.

Complexation study of a tert-butyl-calix[4]arene-based 2-hydroxynaphthalene ligand with uranium(VI) in non-aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Bauer, Anne; Schmeide, Katja [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Surface Processes

2017-06-01

The actinide uranium, well known from nuclear power cycle, plays also a role in rare earth production as it is an undesired constituent of the respective ores. To facilitate the production of rare earth elements, uranium has to be removed. Due to their modifiable selectivity and solubility calix[n]arenes are interesting compounds for the extraction of actinides and lanthanides. The mechanism of uranium(VI) interaction with a tert-butyl-calix[4]arene-based 2-hydroxynaphthalene ligand (L1) was studied by TRLFS, UV-vis spectroscopy and isothermal calorimetry.

Syntheses and catalytic oxotransfer activities of oxo molybdenum(vi) complexes of a new aminoalcohol phenolate ligand.

Science.gov (United States)

Hossain, M K; Haukka, M; Sillanpää, R; Hrovat, D A; Richmond, M G; Nordlander, E; Lehtonen, A

2017-05-30

The new aminoalcohol phenol 2,4-di-tert-butyl-6-(((2-hydroxy-2-phenylethyl)amino)methyl)phenol (H2L) was prepared by a facile solvent-free synthesis and used as a tridentate ligand for new cis-dioxomolybdenum(vi)(L) complexes. In the presence of a coordinating solvent (DMSO, MeOH, pyridine), the complexes crystallise as monomeric solvent adducts while in the absence of such molecules, a trimer with asymmetric Mo[double bond, length as m-dash]O→Mo bridges crystallises. The complexes can catalyse epoxidation of cis-cyclooctene and sulfoxidation of methyl-p-tolylsulfide, using tert-butyl hydroperoxide as oxidant.

Application of confocal Raman micro-spectroscopy for label-free monitoring of oxidative stress in living bronchial cells

Science.gov (United States)

Surmacki, Jakub M.; Quirós Gonzalez, Isabel; Bohndiek, Sarah E.

2018-02-01

Oxidative stress in cancer is implicated in tumor progression, being associated with increased therapy resistance and metastasis. Conventional approaches for monitoring oxidative stress in tissue such as high-performance liquid chromatography and immunohistochemistry are bulk measurements and destroy the sample, meaning that longitudinal monitoring of cancer cell heterogeneity remains elusive. Raman spectroscopy has the potential to overcome this challenge, providing a chemically specific, label free readout from single living cells. Here, we applied a standardized protocol for label-free confocal Raman micro-spectroscopy in living cells to monitor oxidative stress in bronchial cells. We used a quartz substrate in a commercial cell chamber contained within a microscope incubator providing culture media for cell maintenance. We studied the effect of a potent reactive oxygen species inducer, tert-butyl hydroperoxide (TBHP), and antioxidant, N-acetyl-L-cysteine (NAC) on living cells from a human bronchial epithelial cells (HBEC). We found that the Raman bands corresponding to nucleic acids, proteins and lipids were significantly different (pmicro-spectroscopy may be able to monitor the biological impact of oxidative and reductive processes in cells, hence enabling longitudinal studies of oxidative stress in therapy resistance and metastasis at the single cell level.

Synthesis of a highly dispersed CuO catalyst on CoAl-HT for the epoxidation of styrene.

Science.gov (United States)

Hu, Rui; Yang, Pengfei; Pan, Yongning; Li, Yunpeng; He, Yufei; Feng, Junting; Li, Dianqing

2017-10-10

A highly dispersed CuO catalyst was prepared by the deposition-precipitation method and evaluated for the catalytic epoxidation of styrene with tert-butyl hydroperoxide (TBHP) as the oxidant under solvent acetonitrile conditions. Compared with MgAl hydrotalcite (MgAl-HT)-, MgO-, TiO 2 -, C-, and MCM-22-supported catalysts, CuO/CoAl-HT exhibited preferable activity and selectivity towards styrene oxide (72% selectivity at 99.5% styrene conversion) due to its high dispersion of CuO and surface area of Cu. The improved dispersion of CuO/CoAl-HT could be ascribed to the nature of HT support, especially the synergistic effect of acidic and basic sites on the surface, which facilitated the formation of highly dispersed CuO species. A structure-performance relationship study indicated that copper(ii) in CuO was the active site for the epoxidation and oxidation of styrene, and that Cu II of rich electronic density favored the improvement of selectivity of styrene oxide. Based on these results, a reaction mechanism was proposed. Moreover, the preferred catalytic performance of CuO/CoAl-HT could be maintained in five reused cycles.

Protective effects of flavonoids isolated from Korean milk thistle Cirsium japonicum var. maackii (Maxim.) Matsum on tert-butyl hydroperoxide-induced hepatotoxicity in HepG2 cells.

Science.gov (United States)

Jung, Hyun Ah; Abdul, Qudeer Ahmed; Byun, Jeong Su; Joung, Eun-Ji; Gwon, Wi-Gyeong; Lee, Min-Sup; Kim, Hyeung-Rak; Choi, Jae Sue

2017-09-14

Milk thistle leaves and flowers have been traditionally used as herbal remedy to alleviate liver diseases for decades. Korean milk thistle, Cirsium japonicum var. maackii (Maxim.) Matsum has been employed in traditional folk medicine as diuretic, antiphlogistic, hemostatic, and detoxifying agents. The aim of current investigation was to evaluate hepatoprotective properties of the MeOH extract of the roots, stems, leaves and flowers of Korean milk thistle as well as four isolated flavonoids, luteolin, luteolin 5-O-glucoside, apigenin and apigenin 7-O-glucuronide during t-BHP-induced oxidative stress in HepG2 cells. Hepatoprotective potential of the MeOH extracts and flavonoids derived from Korean milk thistle against t-BHP-induced oxidative stress in HepG2 cells were evaluated following MTT method. Incubating HepG2 cells with t-BHP markedly decreased the cell viability and increased the intracellular ROS generation accompanied by depleted GSH levels. Protein expression of heme oxygenase (HO-1) and nuclear factor-E2-related factor 2 (Nrf-2) was determined by Western blot. Our findings revealed that pretreating HepG2 cells with MeOH extracts and bioactive flavonoids significantly attenuated the t-BHP-induced oxidative damage, followed by increased cell viability in a dose-dependent manner. The results illustrate that excess ROS generation was reduced and GSH levels increased dose-dependently when HepG2 cells were pretreated with four flavonoids. Moreover, Western blotting analysis demonstrated that protein expressions of Nrf-2 and HO-1 were also up-regulated by flavonoids treatment. These results clearly demonstrate that the MeOH extracts and flavonoids from Korean milk thistle protected HepG2 cells against oxidative damage triggered by t-BHP principally by modulating ROS generation and restoring depleted GSH levels in addition to the increased Nrf-2/HO-1 signaling cascade. These flavonoids are potential natural antioxidative biomarkers against oxidative stress

Entanglement Dynamics in Miscible Polyisoprene / Poly(p-tert-butyl styrene) Blends

Science.gov (United States)

Watanabe, Hiroshi

2011-03-01

Viscoelastic and dielectric behavior was examined for well entangled, miscible blends of high- M cis-polyisoprene (PI) and poly(p-tert-butyl styrene) (PtBS). The dielectric data of the blends, reflecting the global motion of the PI chains having the type-A dipoles, indicated that PI and PtBS were the fast and slow components therein. At high temperatures T , the blends exhibited two-step entanglement plateau. The high frequency (ω) plateau height was well described by a simple mixing rule of the entanglement length based on the number fraction of the Kuhn segments. At low T , the blend exhibited the Rouse-like power-law behavior of storage and loss moduli, G ' = G ~ω0.5 , in the range of ω where the high- ω plateau was supposed to emerge. This lack of the high- ω plateau was attributed to retardation of the Rouse equilibration of the PI chain over the entanglement length due to the hindrance from the slow PtBS chains: The PI and PtBS chains were equilibrated cooperatively, and the retardation due to PtBS shortened the plateau for PI to a width not resolved experimentally. A simple model for this cooperative equilibration formulated on the basis of the dielectric data described the viscoelastic data surprisingly well.

Di-tert-butyl N-[2,6-bis(methoxymethoxyphenyl]iminodiacetate

Directory of Open Access Journals (Sweden)

Ben Capuano

2009-04-01

Full Text Available The title molecule, C20H31NO8, has pseudo-C2 symmetry about the C—N bond, with the bis(tert-butoxycarbonylamino group twisted from the benzene ring plane by ca 60° and the bulky tert-butoxycarbonyl (Boc groups are orientated away from the substituted aniline group. As part of an antibacterial drug discovery programme furnishing analogues of platensimycin, we unexpectedly synthesized the bis-Boc-protected aniline.

A Shock Tube Study of the CO + OH Reaction Near the Low-Pressure Limit

KAUST Repository

Nasir, Ehson Fawad; Farooq, Aamir

2016-01-01

Rate coefficients for the reaction between carbon monoxide and hydroxyl radical were measured behind reflected shock waves over 700 – 1230 K and 1.2 – 9.8 bar. The temperature/pressure conditions correspond to the predicted low-pressure limit of this reaction, where the channel leading to carbon dioxide formation is dominant. The reaction rate coefficients were inferred by measuring the formation of carbon dioxide using quantum cascade laser absorption near 4.2 µm. Experiments were performed under pseudo-first order conditions with tert-butyl hydroperoxide (TBHP) as the OH precursor. Using ultraviolet laser absorption by OH radicals, the TBHP decomposition rate was measured to quantify potential facility effects under extremely dilute conditions used here. The measured CO + OH rate coefficients are provided in Arrhenius form for three different pressure ranges: kCO+OH (1.2 – 1.6 bar) = 9.14 x 10-13 exp(-1265/T) cm3 molecule-1 s-1 kCO+OH (4.3 – 5.1 bar) = 8.70 x 10-13 exp(-1156/T) cm3 molecule-1 s-1 kCO+OH (9.6 – 9.8 bar) = 7.48 x 10-13 exp(-929/T) cm3 molecule-1 s-1 The measured rate coefficients are found to be lower than the master equation modeling results by Weston et al. [J. Phys. Chem. A, 117 (2013) 821] at 819 K and in closer agreement with the expression provided by Joshi and Wang [Int. J. Chem. Kinet., 38 (2006) 57].

Rate constant measurements for the overall reaction of OH + 1-butanol → products from 900 to 1200 K.

Science.gov (United States)

Pang, Genny A; Hanson, Ronald K; Golden, David M; Bowman, Craig T

2012-03-15

The rate constant for the overall reaction OH + 1-butanol → products was determined in the temperature range 900 to 1200 K from measurements of OH concentration time histories in reflected shock wave experiments of tert-butyl hydroperoxide (TBHP) as a fast source of OH radicals with 1-butanol in excess. Narrow-linewidth laser absorption was employed for the quantitative OH concentration measurement. A detailed kinetic mechanism was constructed that includes updated rate constants for 1-butanol and TBHP kinetics that influence the near-first-order OH concentration decay under the present experimental conditions, and this mechanism was used to facilitate the rate constant determination. The current work improves upon previous experimental studies of the title rate constant by utilizing a rigorously generated kinetic model to describe secondary reactions. Additionally, the current work extends the temperature range of experimental data in the literature for the title reaction under combustion-relevant conditions, presenting the first measurements from 900 to 1000 K. Over the entire temperature range studied, the overall rate constant can be expressed in Arrhenius form as 3.24 × 10(-10) exp(-2505/T [K]) cm(3) molecule(-1) s(-1). The influence of secondary reactions on the overall OH decay rate is discussed, and a detailed uncertainty analysis is performed yielding an overall uncertainty in the measured rate constant of ±20% at 1197 K and ±23% at 925 K. The results are compared with previous experimental and theoretical studies on the rate constant for the title reaction and reasonable agreement is found when the earlier experimental data were reinterpreted.

A Shock Tube Study of the CO + OH Reaction Near the Low-Pressure Limit

KAUST Repository

Nasir, Ehson Fawad

2016-05-16

Rate coefficients for the reaction between carbon monoxide and hydroxyl radical were measured behind reflected shock waves over 700 – 1230 K and 1.2 – 9.8 bar. The temperature/pressure conditions correspond to the predicted low-pressure limit of this reaction, where the channel leading to carbon dioxide formation is dominant. The reaction rate coefficients were inferred by measuring the formation of carbon dioxide using quantum cascade laser absorption near 4.2 µm. Experiments were performed under pseudo-first order conditions with tert-butyl hydroperoxide (TBHP) as the OH precursor. Using ultraviolet laser absorption by OH radicals, the TBHP decomposition rate was measured to quantify potential facility effects under extremely dilute conditions used here. The measured CO + OH rate coefficients are provided in Arrhenius form for three different pressure ranges: kCO+OH (1.2 – 1.6 bar) = 9.14 x 10-13 exp(-1265/T) cm3 molecule-1 s-1 kCO+OH (4.3 – 5.1 bar) = 8.70 x 10-13 exp(-1156/T) cm3 molecule-1 s-1 kCO+OH (9.6 – 9.8 bar) = 7.48 x 10-13 exp(-929/T) cm3 molecule-1 s-1 The measured rate coefficients are found to be lower than the master equation modeling results by Weston et al. [J. Phys. Chem. A, 117 (2013) 821] at 819 K and in closer agreement with the expression provided by Joshi and Wang [Int. J. Chem. Kinet., 38 (2006) 57].

Hepatoprotective Activity of Cichorium endivia L. Extract and Its Chemical Constituents

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Ai-Ping Wang

2011-10-01

Full Text Available The objective of the present study was to investigate the in vitro and in vivo hepatoprotective properties of Cichorium endivia L. extract (CEE, and to identify its chemical constituents. CEE significantly blocked the oxidative stress and cytotoxicity induced by tert-butyl hydroperoxide (t-BHP in HepG2 cells. Meanwhile, oral administration of CEE to mice before the treatment of t-BHP exhibited a markedly protective effect by lowering serum levels of ALT and AST, inhibiting the changes in liver biochemistry including MDA, SOD, GSH and GST, as well as ameliorating the liver injuries according to the histopathological observations. According to the acute oral toxicity test, the LD50 of CEE was greater than 5,000 mg/kg, which demonstrates that the CEE can be considered practically non-toxic. Phytochemical analysis of CEE showed the presence of five compounds identified as 2-furanmethanol-(5'→11-1,3-cyclopentadiene-[5,4-c]-1H-cinnoline, which is a new cinnoline derivative derived from a natural source but not synthesis, 2-phenylethyl-β-D-glucopyranoside, kaempferol-3-O-β-D-glucoside, kaempferol, and adenosine. In the ORAC assay, CEE and its constituents kaempferol and kaempferol-3-O-β-D-glucoside had considerable antioxidant potency. Taken together, CEE protects hepatic tissue from oxidative damage in vitro and in vivo, potentially due to its phenolic substances, and does not cause acute oral toxicity, which suggests that CEE may be a valid and safe remedy to cure liver disease.

Lipid oxidation. Part. 1. Effect of free carboxyl group on the decomposition of lipid hydroperoxide.

Science.gov (United States)

Pokorný, J; Rzepa, J; Janícek, G

1976-01-01

Hydroperoxido butyl oleate was decomposed by heating in excess palmitic acid at 60-120 degrees C. The decomposition followed the kinetics of a first order reaction with formation of both monomeric and oligomeric secondary products. The proportions of oligomers slightly increased with increasing reaction temperature and decreased with increasing concentration of hydroperoxide. The activation energy was 70.4 kJ/mol +/- 4.7 kJ/mol. The decomposition of hydroperoxides proceeded partially by monomolecular cleavage, partially by formation of esters with palmitic acid.

Biosynthesis of tert-butyl (3R,5S)-6-chloro-3,5-dihydroxyhexanoate by carbonyl reductase from Rhodosporidium toruloides in mono and biphasic media.

Science.gov (United States)

Liu, Zhi-Qiang; Wu, Lin; Zheng, Ling; Wang, Wen-Zhong; Zhang, Xiao-Jian; Jin, Li-Qun; Zheng, Yu-Guo

2018-02-01

tert-Butyl (3R,5S)-6-chloro-3,5-dihydroxyhexanoate ((3R,5S)-CDHH) is the key intermediate for synthesis of atorvastatin and rosuvastatin. Carbonyl reductase exhibits excellent activity toward tert-butyl (S)-6-chloro-5-hydroxy-3-oxohexanoate ((S)-CHOH) to synthesize (3R,5S)-CDHH. In this study, a whole cell biosynthesis reaction system to produce (3R,5S)-CDHH was constructed in organic solvents. A solution of 10% (v/v) Tween-80 was introduced to the reaction system as a co-solvent, which greatly enhanced biotransformation process, giving 98.9% yield, >99% ee and 1.8-fold higher space time yield in 5 h bioconversion of 1 M (S)-CHOH, compared with 98.7% yield and >99% ee in 9 h bioconversion of a purely aqueous reaction system. Moreover, a water-octanol biphasic reaction system was built and 20% of octanol was added as reservoir of substrate resulting in 98% yield, >99% ee and 4.08 mmol L -1  h -1  g -1 (wet cell weight) space time yield. This study paved a way for the whole cell biosynthesis of (3R,5S)-CDHH in mono and biphasic media. Copyright © 2017 Elsevier Ltd. All rights reserved.

Efficient epoxidation of propene using molecular catalysts

DEFF Research Database (Denmark)

Markovits, Iulius I. E.; Anthofer, Michael H.; Kolding, Helene

2014-01-01

The epoxidation of propene is performed in homogeneous phase using various molecular catalysts and H2O2 or tert-butyl hydroperoxide as oxidants. A comparison between some molybdenum catalysts and methyltrioxorhenium (MTO) shows that the well known Re catalyst is the best among the examined...

Directed Evolution of Carbonyl Reductase from Rhodosporidium toruloides and Its Application in Stereoselective Synthesis of tert-Butyl (3R,5S)-6-Chloro-3,5-dihydroxyhexanoate.

Science.gov (United States)

Liu, Zhi-Qiang; Wu, Lin; Zhang, Xiao-Jian; Xue, Ya-Ping; Zheng, Yu-Guo

2017-05-10

tert-Butyl (3R,5S)-6-chloro-3,5-dihydroxyhexanoate ((3R,5S)-CDHH) is a key intermediate of atorvastatin and rosuvastatin synthesis. Carbonyl reductase RtSCR9 from Rhodosporidium toruloides exhibited excellent activity toward tert-butyl (S)-6-chloro-5-hydroxy-3-oxohexanoate ((S)-CHOH). For the activity of RtSCR9 to be improved, random mutagenesis and site-saturation mutagenesis were performed. Three positive mutants were obtained (mut-Gln95Asp, mut-Ile144Lys, and mut-Phe156Gln). These mutants exhibited 1.94-, 3.03-, and 1.61-fold and 1.93-, 3.15-, and 1.97-fold improvement in the specific activity and k cat /K m , respectively. Asymmetric reduction of (S)-CHOH by mut-Ile144Lys coupled with glucose dehydrogenase was conducted. The yield and enantiomeric excess of (3R,5S)-CDHH reached 98 and 99%, respectively, after 8 h bioconversion in a single batch reaction with 1 M (S)-CHOH, and the space-time yield reached 542.83 mmol L -1 h -1 g -1 wet cell weight. This study presents a new carbonyl reductase for efficient synthesis of (3R,5S)-CDHH.

Thermodynamic properties of tert-butylbenzene and 1,4-di-tert-butylbenzene

International Nuclear Information System (INIS)

Chirico, Robert D.; Steele, William V.

2009-01-01

Heat capacities, enthalpies of phase transitions, and derived thermodynamic properties over the temperature range 5 < (T/K) < 442 were determined with adiabatic calorimetry for tert-butylbenzene (TBB) {Chemical Abstracts Service registry number (CASRN) [98-06-6]} and 1,4-di-tert-butylbenzene (DTBB) {CASRN [1012-72-2]}. A crystal to plastic crystal transition very near the triple-point temperature of DTBB was observed. New vapor pressures near the triple-point temperature are also reported for DTBB for the liquid and crystal states. These new measurements, when combined with published results, allow calculation of the thermodynamic properties for the ideal gas state for both compounds. The contribution of the tert-butyl group to the entropy of the ideal gas is determined quantitatively here for the first time based on the calorimetric results over the temperature range 298.15 < (T/K) < 600. Comparisons with literature values are shown for all measured and derived properties, including entropies for the ideal gas derived from quantum chemical calculations

n-BA/KOH/t-BHP behaviour in the natural rubber latex vulcanization by gamma rays

International Nuclear Information System (INIS)

Souza, A. de.

1994-01-01

Natural rubber latex was vulcanized in the absence and in the presence of sensitizer (S), with gamma ray from 60 Co source, panoramic type, at the dose rate range of 1,20-1,33 kGy/h. The components of used S were n-butyl acrylate (n-BA), the KOH as stabilizer and t-butyl hydroperoxide (t-BHP) as co-S. The purpose of this work was to study the efficiency and the behaviour of each component of S in the irradiated latex crosslinking by tensile strength (T b ), volume fraction and permanent set. In the absence of S occur straight crosslinking between macromolecular adjacent radicals. IN the presence of S, the n-BA participates in the crosslinking through acrylic bridges between macromolecules. (author)

Peroxidative damage of mitochondrial respiration is substrate-dependent

Czech Academy of Sciences Publication Activity Database

Endlicher, R.; Křiváková, P.; Rauchová, Hana; Nůsková, Hana; Červinková, Z.; Drahota, Zdeněk

2009-01-01

Roč. 58, č. 5 (2009), s. 685-692 ISSN 0862-8408 R&D Projects: GA ČR(CZ) GA303/06/1261 Institutional research plan: CEZ:AV0Z50110509 Keywords : mitochondrial enzymes * peroxidative damage * tert-butyl hydroperoxide Subject RIV: CE - Biochemistry Impact factor: 1.430, year: 2009

An experimental and theoretical kinetic study of the reaction of OH radicals with tetrahydrofuran

KAUST Repository

Giri, Binod; Khaled, Fathi; Szőri, Milá n; Viskolcz, Bé la; Farooq, Aamir

2016-01-01

by the rapid thermal decomposition of tert-butyl hydroperoxide, and a UV laser absorption technique was used to monitor the mole fraction of OH radicals. High-level CCSD(T)/cc-pV(D,T)Z//MP2/aug-cc-pVDZ quantum chemical calculations were performed to explore

Poly[[[diisothiocyanatocobalt(II]-bis[μ-4-tert-butyl-2,6-bis(1,2,4-triazol-1-ylmethylphenol

Directory of Open Access Journals (Sweden)

2009-03-01

Full Text Available In the title compound, {[Co(NCS2(C16H20N6O2]·2C3H7NO·2H2O}n, each CoII ion located on an inversion center is six-coordinated by four equatorial N atoms from four different 4-tert-butyl-2,6-bis(1,2,4-triazol-1-ylmethylphenol (L ligands, and by two N atoms from two axial thiocyanate anions [Co—N = 2.104 (3–2.144 (3 Å]. The metal centres are connected via the bidentate L ligands into two-dimensional polymeric layers parallel to bc plane. The dimethylformamide and solvent water molecules participate in intermolecular O—H...O and O—H...S hydrogen bonds, which consolidate the crystal packing.

5-tert-Butyl-2-(4'-[{sup 18}F]fluoropropynylphenyl)-1,3-dithiane oxides: potential new GABA{sub A} receptor radioligands

Energy Technology Data Exchange (ETDEWEB)

Li Xuehe; Jung, Yong-Woon; Snyder, Scott E.; Blair, Joseph; Sherman, Philip S.; Desmond, Timothy; Frey, Kirk A. [Department of Radiology, University of Michigan Medical School, Ann Arbor, MI 48109 (United States); Kilbourn, Michael R. [Department of Radiology, University of Michigan Medical School, Ann Arbor, MI 48109 (United States)], E-mail: mkilbour@umich.edu

2008-07-15

As potential new ligands targeting the binding site of {gamma}-aminobutyric acid (GABA) receptor ionophore, trans-5-tert-butyl-2-(4'-fluoropropynylphenyl)-2-methyl-1,1-dioxo-1, 3-dithiane (1) and cis/trans-5-tert-butyl-2-(4'-fluoropropynylphenyl)-2-methyl-1,1,3, 3-tetroxo-1,3-dithiane (2) were selected for radiolabeling and initial evaluation as in vivo imaging agents for positron emission tomography (PET). Both compounds exhibited identical high in vitro binding affinities (K{sub i}=6.5 nM). Appropriate tosylate-substituted ethynyl precursors were prepared by multistep syntheses involving stepwise sulfur oxidation and chromatographic isolation of desired trans isomers. Radiolabeling was accomplished in one step using nucleophilic [{sup 18}F]fluorination. In vivo biodistribution studies with trans-[{sup 18}F]1 and trans-[{sup 18}F]2 showed significant initial uptake into mouse brain and gradual washout, with heterogeneous regional brain distributions and higher retention in the cerebral cortex and cerebellum and lower retention in the striatum and pons-medulla. These regional distributions of the new radioligands correlated with in vitro and ex vivo measures of standard radioligands binding to the ionophore- and benzodiazepine-binding sites of GABA{sub A} receptor in rodent brain. A comparison of these results with previously prepared radiotracers for other neurochemical targets, including successes and failures as in vivo radioligands, suggests that higher-affinity compounds with increased retention in target brain tissues will likely be needed before a successful radiopharmaceutical for human PET imaging can be identified.

Solvent extraction of Ca2+, Ba2+, Cu2+, Zn2+, Cd2+, Pb2+, UO22+, Mn2+, Co2+ and Ni2+ into nitrobenzene using strontium dicarbol-lylcobaltate and tetra-tert-butyl p-tert-butylcalix[4]arene tetraacetate

Directory of Open Access Journals (Sweden)

E. MAKRLÍK

2008-12-01

Full Text Available The exchange extraction constants corresponding to the general equilibrium M2+(aq + SrL2+(nb D ML2+ (nb + Sr2+ (aq occurring in the two-phase water–nitrobenzene system (M2+ = Ca2+, Ba2+, Cu2+, Zn2+, Cd2+, Pb2+, UO22+, Mn2+, Co2+ or Ni2+; L = tetra-tert-butyl p-tert-butylcalix[4]arene tetraacetate; aq = aqueous phase; nb = nitrobenzene phase were evaluated from extraction experiments and -activity measurements. Furthermore, the stability constants of the ML2+ complexes in water saturated nitrobenzene were calculated; they were found to increase in the cation order Ba2+ < Mn2+ < Pb2+, Co2+ < Cu2+, Zn2+ < Cd2+, Ni2+ < UO22+ < Ca2+.

Degradation of methyl tert-butyl ether by gel immobilized Methylibium petroleiphilum PM1.

Science.gov (United States)

Chen, Dongzhi; Chen, Jianmeng; Zhong, Weihong; Cheng, Zhuowei

2008-07-01

Cells of Methylibium petroleiphilum PM1 were immobilized in gel beads to degrade methyl tert-butyl ether (MTBE). Calcium alginate, agar, polyacrylamide and polyvinvyl alcohol were screened as suitable immobilization matrices, with calcium alginate demonstrating the fastest MTBE-degradation rate. The rate was accelerated by 1.8-fold when the beads had been treated in physiological saline for 24h at 28 degrees C. MTBE degradation in mineral salts medium (MSM) was accompanied by the increase of biomass. The half-life of MTBE-degradation activity for the encapsulated cells stored at 28 degrees C was about 120 h, which was obviously longer than that of free cells (approximately 36 h). Efficient reusability of the beads up to 30 batches was achieved in poor nutrition solution as compared to only 6 batches in MSM. The immobilized cells could be operated in a packed-bed reactor for degradation of 10 mg L(-1) MTBE in groundwater with more than 99% removal efficiency at hydraulic retention time of 20 min. These results suggested that immobilized cells of PM1 in bioreactor might be applicable to a groundwater treatment system for the removal of MTBE.

Synthesis, spectroscopy, magnetic and redox behaviors of copper(II) complexes with tert-butylated salen type ligands bearing bis(4-aminophenyl)ethane and bis(4-aminophenyl)amide backbones.

Science.gov (United States)

Kasumov, Veli T; Yerli, Yusuf; Kutluay, Aysegul; Aslanoglu, Mehmet

2013-03-01

New salen type ligands, N,N'-bis(X-3-tert-butylsalicylidene)-4,4'-ethylenedianiline [(X=H (1), 5-tert-butyl (2)] and N,N'-bis(X-3-tert-butylsalicylidene)-4,4'-amidedianiline [X=H (3), 5-tert (4)] and their copper(II) complexes 5-8, have been synthesized. Their spectroscopic (IR, (1)H NMR, UV/vis, ESR) properties, as well as magnetic and redox-reactivity behavior are reported. IR spectra of 7 and 8 indicate the coordination of amide oxygen atoms of 3 and 4 ligands to Cu(II). The solid state ESR spectra of 5-8 exhibits less informative exchange narrowed isotropic or anisotropic signals with weak unresolved low field patterns. The magnetic moments of 5 (2.92 μ(B) per Cu(II)) and 6 (2.79 μ(B) per Cu(II)) are unusual for copper(II) complexes and considerably higher than those for complexes 7 and 8. Cryogenic measurements (300-10 K) show weak antiferromagnetic exchange interactions between the copper(II) centers in complexes 6 and 8. The results of electrochemical and chemical redox-reactivity studies are discussed. Copyright © 2012 Elsevier B.V. All rights reserved.

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

... B3LYP level of theory confirming the experimental data. Our results demonstrated well the efficiency, selectivity and stability of this new catalyst in the oxidation of alcohols in ethanol and tert-butyl hydroperoxide (tBuOOH) as a green solvent and oxidant, respectively. Turnover number and reusability have proven the high ...

Microwave-Assisted Synthesis and Crystal Structure of Oxo(diperoxo(4,4'-di-tert-butyl-2,2'-bipyridine-molybdenum(VI

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Alírio E. Rodrigues

2009-09-01

Full Text Available The oxodiperoxo complex MoO(O22(tbbpy (tbbpy = 4,4'-di-tert-butyl-2,2'- bipyridine was isolated from the reaction of MoO2Cl2(tbbpy in water under microwaveassisted heating at 120 ºC for 4 h. The structure of the oxodiperoxo complex was determined by single crystal X-ray diffraction. The MoVI centre is seven-coordinated with a geometry which strongly resembles a highly distorted bipyramid. Individual MoO(O22(tbbpy complexes are interdigitated along the [010] direction to form a column. The crystal structure is formed by the close packing of the columnar-stacked complexes. Interactions between neighbouring columns are essentially of van der Waals type mediated by the need to effectively fill the available space.

Characterization and photoconductivity study of well-defined C60 terminated poly(tert-butyl acrylate-b-styrene)

International Nuclear Information System (INIS)

Yang Dong; Li Lang; Wang Changchun

2004-01-01

Atom transfer radical polymerization (ATRP) catalyzed by N,N',N',N'',N''-pentamethyldiethylenetriamine (PMDETA)/CuBr was performed to synthesize poly (tert-butyl acrylate) (PtBA-Br) with predesigned molecular weight and narrow polydispersity. Using the PtBA-Br as macroinitiator, the PtBA-block-PS copolymer was prepared through ATRP. After terminated bromine atom was converted to end-functional azide group (P(tBA-b-St)-N 3 ), C 60 end-capped PtBA-PS block copolymers (P(tBA-b-St)-C 60 ) were synthesized by reacting C 60 with P(tBA-b-St)-N 3 . GPC characterizations showed that C 60 was chemically bonded to the end of P(tBA-b-St) chain and the products were mono-substituted. FT-IR, UV-Vis measurements confirmed that hydrolysis of P(tBA-b-St)-C 60 resulted in amphiphilic C 60 end-capped PAA-PS block copolymers. In additional, the photoconductivity of P(tBA-b-St)-C 60 was measured

Accelerated Aging during Chronic Oxidative Stress: A Role for PARP-1

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Daniëlle M. P. H. J. Boesten

2013-01-01

Full Text Available Oxidative stress plays a major role in the pathophysiology of chronic inflammatory disease and it has also been linked to accelerated telomere shortening. Telomeres are specialized structures at the ends of linear chromosomes that protect these ends from degradation and fusion. Telomeres shorten with each cell division eventually leading to cellular senescence. Research has shown that poly(ADP-ribose polymerase-1 (PARP-1 and subtelomeric methylation play a role in telomere stability. We hypothesized that PARP-1 plays a role in accelerated aging in chronic inflammatory diseases due to its role as coactivator of NF-κb and AP-1. Therefore we evaluated the effect of chronic PARP-1 inhibition (by fisetin and minocycline in human fibroblasts (HF cultured under normal conditions and under conditions of chronic oxidative stress, induced by tert-butyl hydroperoxide (t-BHP. Results showed that PARP-1 inhibition under normal culturing conditions accelerated the rate of telomere shortening. However, under conditions of chronic oxidative stress, PARP-1 inhibition did not show accelerated telomere shortening. We also observed a strong correlation between telomere length and subtelomeric methylation status of HF cells. We conclude that chronic PARP-1 inhibition appears to be beneficial in conditions of chronic oxidative stress but may be detrimental under relatively normal conditions.

Studies on bis(halogeno) dioxomolybdenum(VI)-bipyridine complexes: synthesis and catalytic activity.

Science.gov (United States)

Günyar, Alev; Zhou, Ming-Dong; Drees, Markus; Baxter, Paul N W; Bassioni, Ghada; Herdtweck, Eberhardt; Kühn, Fritz E

2009-10-28

Dioxomolybdenum(VI) complexes with the general formula [MoO2Cl2L2] (L2=3,3'-dimethyl-2,2'-bipyridine, 5,5'-dimethyl-2,2'-bipyridine, 6,6'-dimethyl-2,2'-bipyridine, 4,4'-dibromo-2,2'-bipyridine, 5,5'-dibromo-2,2'-bipyridine, 5,5'-diamino-2,2'-bipyridine; 5,5'-dinitro-2,2'-bipyridine; 5,5'-di-ethoxycarbonyl-2,2'-bipyridine; 6-phenyl-2,2'-bipyridine; 2,2':6',2''-terpyridine) have been prepared and characterised. [MoO2Cl2(5,5'-di-ethoxycarbonyl-2,2'-bipyridine)] has been examined by single crystal X-ray analysis. The complexes were applied as homogenous catalysts for the epoxidation of cyclooctene with tert-butyl hydroperoxide (TBHP) as oxidising agent. The new compounds show an overall high activity and are highly selective catalysts in the epoxidation of cyclooctene. The stability of the complexes and differences in the catalytic activity can be clearly attributed to electronic contributions of the functional groups on bipyridine ligands and to steric restrictions. DFT calculations have assisted in a better understanding of the stability of the complexes and are in agreement with experiment. The influence of the terminal oxo ligands and the Lewis base ligands on the Mo center keep the compounds on quite a stable level of electron density.

Active Fragment of Veronica ciliata Fisch. Attenuates t-BHP-Induced Oxidative Stress Injury in HepG2 Cells through Antioxidant and Antiapoptosis Activities

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Yiran Sun

2017-01-01

Full Text Available Excessive amounts of reactive oxygen species (ROS in the body are a key factor in the development of hepatopathies such as hepatitis. The aim of this study was to assess the antioxidation effect in vitro and hepatoprotective activity of the active fragment of Veronica ciliata Fisch. (VCAF. Antioxidant assays (DPPH, superoxide, and hydroxyl radicals scavenging were conducted, and hepatoprotective effects through the application of tert-butyl hydroperoxide- (t-BHP- induced oxidative stress injury in HepG2 cells were evaluated. VCAF had high phenolic and flavonoid contents and strong antioxidant activity. From the perspective of hepatoprotection, VCAF exhibited a significant protective effect on t-BHP-induced HepG2 cell injury, as indicated by reductions in cytotoxicity and the levels of ROS, 8-hydroxydeoxyguanosine (8-OHdG, and protein carbonyls. Further study demonstrated that VCAF attenuated the apoptosis of t-BHP-treated HepG2 cells by suppressing the activation of caspase-3 and caspase-8. Moreover, it significantly decreased the levels of ALT and AST, increased the activities of acetyl cholinesterase (AChE, glutathione (GSH, superoxide dismutase (SOD, and catalase (CAT, and increased total antioxidative capability (T-AOC. Collectively, we concluded that VCAF may be a considerable candidate for protecting against liver injury owing to its excellent antioxidant and antiapoptosis properties.

DNA Protecting Activities of Nymphaea nouchali (Burm. f Flower Extract Attenuate t-BHP-Induced Oxidative Stress Cell Death through Nrf2-Mediated Induction of Heme Oxygenase-1 Expression by Activating MAP-Kinases

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Md Badrul Alam

2017-09-01

Full Text Available This study was performed to investigate the antioxidant activities of Nymphaea nouchali flower (NNF extract and the underlying mechanism using RAW 264.7 cells. The presence of gallic acid, catechin, epicatechin, epigallocatechin, epicatechin gallate, caffeic acid, quercetin, and apigenin in the NNF was confirmed by high-performance liquid chromatography (HPLC. The extract had a very potent capacity to scavenge numerous free radicals. NNF extract was also able to prevent DNA damage and quench cellular reactive oxygen species (ROS generation induced by tert-Butyl hydroperoxide (t-BHP with no signs of toxicity. The NNF extract was able to augment the expression of both primary and phase II detoxifying enzyme, resulting in combat the oxidative stress. This is accomplished by phosphorylation of mitogen-activated protein kinase (MAP kinase (p38 kinase and extracellular signal-regulated kinase (ERK followed by enhancing the nuclear translocation of the nuclear factor erythroid 2-related factor 2 (Nrf2. This attenuates cellular ROS generation and confers protection from cell death. Altogether, the results of current study revealed that Nymphaea nouchali flower could be a source of natural phytochemicals that could lead to the development of new therapeutic agents for preventing oxidative stress associated diseases and attenuating disease progression.

Determination of organic peroxides by liquid chromatography with on-line post-column ultraviolet irradiation and peroxyoxalate chemiluminescence detection.

Science.gov (United States)

Wada, Mitsuhiro; Inoue, Keiyu; Thara, Ayuko; Kishikawa, Naoya; Nakashima, Kenichiro; Kuroda, Naotaka

2003-02-14

A HPLC method was developed for the simultaneous determination of organic peroxides and hydrogen peroxide with peroxyoxalate chemiluminescence (PO-CL) detection following on-line UV irradiation. Organic peroxides [i.e., benzoyl peroxide (BP), tert.-butyl hydroperoxide (BHP), tert.-butyl perbenzoate (BPB), cumene hydroperoxide (CHP)] were UV irradiated (254 nm, 15 W) to generate hydrogen peroxide, which was determined by PO-CL detection. The conditions for UV irradiation and PO-CL detection were optimized by a flow injection analysis (FIA) system. Generation of hydrogen peroxide from peroxides with on-line UV irradiation also was confirmed by the FIA system by incorporating an enzyme column reactor immobilized with catalase. The separation of four organic peroxides and hydrogen peroxide by HPLC was accomplished isocratically on an ODS column within 30 min. The detection limits (signal-to-noise ratio=3) were 1.1 microM for hydrogen peroxide, 6.8 microM for BP, 31.3 microM for BHP, 7.5 microM for BPB and 1.3 microM for CHP. The proposed method was applied to the determination of BP in wheat flour.

Synthesis, Crystal Growth, Spectroscopic and Electrical Properties of 5-tert-Butyl-1,2,3-trinitrobenzene

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S. Sahaya Jude Dhas

2013-01-01

Full Text Available 5-tert-Butyl-1,2,3-trinitrobenzene (TBTB was synthesized and characterized by NMR so as to confirm the structure. Single crystals were obtained from methanol by solvent evaporation technique at room temperature. Optically transparent single crystals with dimension up to 17×4×3 mm3 have been grown by submerged seed solution method within a period of 30 days. The modes of vibration of different molecular groups present in the title compound were identified by FTIR and FT-Raman spectral analyses, and it was found with the tabulation that both of the spectral vibrations are very close to each other confirming the existence of specific functional groups in the crystal. Optical behaviour of the crystal was analyzed by UV-Vis absorption studies, and the value of the optical band gap energy (Eg of the crystal has been determined using the optical absorption spectrum. The dielectric behaviour and AC conductivity of the grown crystals were also analyzed, and it is shown that both properties vary with respect to frequency and do not vary in accordance with temperature.

Two DSC Glass Transitions in Miscible Blends of Polyisoprene / Poly(4-tert-butyl styrene)

Science.gov (United States)

Zhao, Junshu; Sun, Ye; Yu, Lian; Ediger, Mark

2009-03-01

Conventional and temperature modulated differential scanning calorimetry experiments have been carried out on miscible blends of polyisoprene (PI) and poly(4-tert-butyl styrene) (P4tBS) over a broad composition range. This system is characterized by an extraordinarily large component Tg difference (˜215 K) between the two homopolymers. Two distinct calorimetric Tgs were observed in blends with an intermediate composition range (25%˜50% PI) by both conventional and temperature modulated DSC. Good agreement was found between the Tg values measured by the two methods. Fitting of the measured Tgs to the Lodge-McLeish model gives a φself of 0.62˜0.64 for PI in this blend and 0.02˜0.05 for P4tBS. The extracted φself for PIis comparable to reported values for PEO in blends with PMMA and is significantly larger than those reported for other PI blends with smaller component Tg differences. This observation suggests the presence of a confinement effect in PI/P4tBS blends, which results in enhanced fast component dynamics below the effective Tg of the slow component.

Artificial Neural Network Approach to Predict Biodiesel Production in Supercritical tert-Butyl Methyl Ether

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Obie Farobie

2016-05-01

Full Text Available In this study, for the first time artificial neural network was used to predict biodiesel yield in supercritical tert-butyl methyl ether (MTBE. The experimental data of biodiesel yield conducted by varying four input factors (i.e. temperature, pressure, oil-to-MTBE molar ratio, and reaction time were used to elucidate artificial neural network model in order to predict biodiesel yield. The main goal of this study was to assess how accurately this artificial neural network model to predict biodiesel yield conducted under supercritical MTBE condition. The result shows that artificial neural network is a powerful tool for modeling and predicting biodiesel yield conducted under supercritical MTBE condition that was proven by a high value of coefficient of determination (R of 0.9969, 0.9899, and 0.9658 for training, validation, and testing, respectively. Using this approach, the highest biodiesel yield was determined of 0.93 mol/mol (corresponding to the actual biodiesel yield of 0.94 mol/mol that was achieved at 400 °C, under the reactor pressure of 10 MPa, oil-to-MTBE molar ratio of 1:40 within 15 min of reaction time.

Metal-free oxidative olefination of primary amines with benzylic C-H bonds through direct deamination and C-H bond activation.

Science.gov (United States)

Gong, Liang; Xing, Li-Juan; Xu, Tong; Zhu, Xue-Ping; Zhou, Wen; Kang, Ning; Wang, Bin

2014-09-14

An oxidative olefination reaction between aliphatic primary amines and benzylic sp(3) C-H bonds has been achieved using N-bromosuccinimide as catalyst and tert-butyl hydroperoxide as oxidant. The olefination proceeds under mild metal-free conditions through direct deamination and benzylic C-H bond activation, and provides easy access to biologically active 2-styrylquinolines with (E)-configuration.

(1S,3S,4S-tert-Butyl N-[1-benzyl-3-hydroxy-5-phenyl-4-(picolinamidopentyl]carbamate

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Jian-Feng Zheng

2008-07-01

Full Text Available The title compound, C29H35N3O4, was obtained by the reaction of (2S,4S,5S-tert-butyl N-(4-amino-1-benzyl-3-hydroxy-5-phenylpentylcarbamate and picolinic acid using oxalyl chloride as a chlorinating reagent to activate the carboxyl group. In the crystal structure there are two molecules in the asymmetric unit, which are aligned edge-to-face. In one molecule, the pyridyl ring forms a dihedral angle of 22.0 (1° with the phenyl ring of the terminal benzyl group and 14.3 (1° with the other phenyl ring; in the other molecule, the corresponding angles are 12.1 (1 and 10.6 (1°, respectively. The packing is stabilized by intermolecular hydrogen bonds and C—H...π interactions.

Cytotoxic and DNA-damaging effects of methyl tert-butyl ether and its metabolites on HL-60 cells in vitro

Energy Technology Data Exchange (ETDEWEB)

Tang, G.H. [Xian Medical Univ. (China); Shen, Y.; Shen, H.M. [National Univ. of Singapore (Singapore)] [and others

1996-12-31

Methyl tert-butyl ether (MTBE) is a widely used oxygenate in unleaded gasoline; however, few studies have been conducted on the toxicity of this compound. This study evaluates the cytotoxic and DNA-damaging effects of MTBE and its metabolites in a human haemopoietic cell line, HL-60. The metabolites of MTBE studied include tertiary butyl alcohol (TBA), {alpha}-hydroxyisobutyric acid (HIBA), and formaldehyde. Comet assay is used to assess DNA damage, and the cytotoxicity is investigated by lactate dehydrogenease (LDH) release. The results show no significant cytotoxic effects of MTBE, TBA, and HIBA over a concentration ranging from 1 to 30 mM. Formaldehyde, in contrast, causes a substantial LDH release at a concentration of 5 {mu}M. Hydrogen peroxide, a known oxidative agent, at concentrations ranging from 10 to 100 {mu}M, produces a significant dose-related increase in DNA damage, whereas a much higher concentration of MTBE (1 to 30 mM) is required to produce a similar observation. The genotoxic effects of TBA and HIBA appear to be identical to that of MTBE. Conversely, DNA damage is observed for formaldehyde at a relatively low concentration range (5 to 100 {mu}M). These findings suggest that MTBE and its metabolites, except formaldehyde, have relatively low cytotoxic and genotoxic effects. 16 refs., 4 figs.

Temperature-Induced Desorption of Methyl tert-Butyl Ether Confined on ZSM-5: An In Situ Synchrotron XRD Powder Diffraction Study

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Elisa Rodeghero

2017-02-01

Full Text Available The temperature-induced desorption of methyl tert-butyl ether (MTBE from aqueous solutions onto hydrophobic ZSM-5 was studied by in situ synchrotron powder diffraction and chromatographic techniques. This kind of information is crucial for designing and optimizing the regeneration treatment of such zeolite. The evolution of the structural features monitored by full profile Rietveld refinements revealed that a monoclinic (P21/n to orthorhombic (Pnma phase transition occurred at about 100 °C. The MTBE desorption process caused a remarkable change in the unit-cell parameters. Complete MTBE desorption was achieved upon heating at about 250 °C. Rietveld analysis demonstrated that the desorption process occurred without any significant zeolite crystallinity loss, but with slight deformations in the channel apertures.

Synthesis and dynamic NMR study of ketenimines derived from tert-butyl isocyanide, alkyl 2-arylamino-2-oxo-acetates, and dialkyl acetylenedicarboxylates.

Science.gov (United States)

Yavari, Issa; Nasiri, Farough; Djahaniani, Horieh

2004-01-01

The adduct produced in the reaction between tert-butyl isocyanide and dialkyl acetylenedicarboxylates was trapped by alkyl 2-arylamino-2-oxo-acetates. When the aryl group is 2-methyl-6-nitrophenyl or 2,6-di-isopropylphenyl, the product exists as two stable rotamers at room temperature as a result of restricted rotation around the Ar-N single bond. When the aryl group is 1-naphthyl or 8-quinolinyl, dynamic NMR effects are observed in the 1H NMR spectra. The calculated free-energy of activation for interconversion of the rotational isomers in 1-naphthyl and 8-quinolinyl derivatives amounts to about 99+/-2 and 68.5+/-2 kJ mol(-1), respectively.

Interactions of poly(tert-butyl acrylate)-poly(styrene) diblock copolymers with lipids at the air-water interface.

Science.gov (United States)

Mudgil, Poonam; Dennis, Gary R; Millar, Thomas J

2006-08-29

Diblock copolymers with hydrophilic poly(tert-butyl acrylate) (PtBA) and hydrophobic poly(styrene) (PS) blocks were synthesized with a view to use them as a surfactant in tear film for increasing the ocular comfort in dry eye syndrome. Interactions of six PtBA-PS copolymers with four important lipids found in the tear film, namely cholesterol, cholesteryl palmitate, dipalmitoyl phosphatidylcholine, and phosphatidylinositol, were studied at the air-water interface using a Langmuir trough. Thermodynamics of mixing of the copolymers and the lipids in the mixed monolayers was determined by calculating excess free energy of mixing. The diblock copolymers showed repulsive interactions with cholesteol and cholesteryl palmitate, near neutral interactions with dipalmitoyl phosphatidylcholine, and attractive interactions with phosphatidylinositol. The lipids interacted with the PS component of the copolymer. The results indicate that a copolymer with a small hydrophilic group and a big hydrophobic group can be a likely candidate for forming stable interactions with the lipids present in the tear film and hence increase the ocular comfort.

Synthesis, characterization and gas separation properties of novel polyimides containing cardo and tert-butyl-m-terphenyl moieties

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L. A. Bermejo

2018-05-01

Full Text Available A series of aromatic polyimides has been obtained by the reaction of two dianhydrides, the commercial 2,2′-bis(3,4-dicarboxyphenylhexafluoropropane dianhydride (6FDA and another having a 5′-tert-butyl-m-terphenyl moiety (BTPDA, with several diamines, including two that have a cardo structure (derived from 9H-fluorene, one of them bearing methyl groups ortho to the amino functionalities (TMeCardo. The solubility, and also the thermal, mechanical, and gas separation properties of the corresponding polyimide membranes were evaluated and compared in order to explore the effect of the different groups in the polyimide backbone. The novel polyimides, which were derived from BTPDA and the cardo diamines, showed high thermal stability, excellent solubility in organic solvents and good gas separation properties, especially the polyimide that bore the ortho methyl substituents. The behavior was especially good for the pair O2/N2, where the TMeCardo polymer overpassed the Robeson upper bound.

Highly efficient enzymatic synthesis of tert-butyl (S)-6-chloro-5-hydroxy-3-oxohexanoate with a mutant alcohol dehydrogenase of Lactobacillus kefir.

Science.gov (United States)

He, Xiu-Juan; Chen, Shao-Yun; Wu, Jian-Ping; Yang, Li-Rong; Xu, Gang

2015-11-01

tert-Butyl (S)-6-chloro-5-hydroxy-3-oxohexanoate ((S)-CHOH) is a valuable chiral synthon, which is used for the synthesis of the cholesterol-lowering drugs atorvastatin and rosuvastatin. To date, only the alcohol dehydrogenases from Lactobacillus brevis (LbADH) and Lactobacillus kefir (LkADH) have demonstrated catalytic activity toward the asymmetric reduction of tert-butyl 6-chloro-3,5-dioxohexanoate (CDOH) to (S)-CHOH. Herein, a tetrad mutant of LkADH (LkTADH), A94T/F147L/L199H/A202L, was screened to be more efficient in this bioreduction process, exhibiting a 3.7- and 42-fold improvement in specific activity toward CDOH (1.27 U/mg) over LbADH (0.34 U/mg) and wild-type LkADH (0.03 U/mg), respectively. The molecular basis for the improved catalytic activity of LkTADH toward CDOH was investigated using homology modeling and docking analysis. Two major issues had a significant impact on the biocatalytic efficiency of this process, including (i) the poor aqueous stability of the substrate and (ii) partial substrate inhibition. A fed-batch strategy was successfully developed to address these issues and maintain a suitably low substrate concentration throughout the entire process. Several other parameters were also optimized, including the pH, temperature, NADP(+) concentration and cell loading. A final CDOH concentration of 427 mM (100 g/L) gave (S)-CHOH in 94 % yield and 99.5 % e.e. after a reaction time of 38 h with whole cells expressing LkTADH. The space-time yield and turnover number of NADP(+) in this process were 10.6 mmol/L/h and 16,060 mol/mol, respectively, which were the highest values ever reported. This new approach therefore represents a promising alternative for the efficient synthesis of (S)-CHOH.

Viscosities of binary mixtures of some n-ethoxyethanols with ethyl tert-butyl ether at T = (293.15, 298.15, and 303.15) K

International Nuclear Information System (INIS)

Cwiklinska, Aneta; Dzikowski, Tomasz; Szychowski, Dariusz; Kinart, Wojciech J.; Kinart, Cezary M.

2007-01-01

Viscosities at T = (293.15, 298.15, and 303.15) K in the binary mixtures of ethyl tert-butyl ether with 2-ethoxyethanol, 2-(2-ethoxyethoxy)ethanol, and 2-[2-(2-ethoxyethoxy)ethoxy]ethanol have been measured over the entire range of mixture compositions. From the experimental data, deviations in the viscosity (Δln η) and excess energies of activation for viscous flow (ΔG *E ) have been calculated. The viscosity data were correlated with equations of Hind et al., Grunberg and Nissan, Auslaender, and McAllister. The results for Δln η and ΔG *E are discussed in terms of intermolecular interactions and structure of studied binary mixtures

Bis(formylphenolatocobalt(II-Mediated Alternating Radical Copolymerization of tert-Butyl 2-Trifluoromethylacrylate with Vinyl Acetate

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Sanjib Banerjee

2017-12-01

Full Text Available The organometallic-mediated radical polymerization (OMRP of vinyl acetate (VAc and its OMR copolymerization (OMRcoP with tert-butyl 2-trifluoromethylacrylate (MAF-TBE mediated by Co(SAL2 (SAL = 2-formylphenolato or deprotonated salicylaldehyde produced relatively well-defined PVAc and poly(VAc-alt-MAF-TBE copolymers at moderate temperature (<40 °C in bulk. The resulting alternating copolymer was characterized by 1H-, 13C- and 19F-nuclear magnetic resonance (NMR spectroscopies, and by size exclusion chromatography. The linear first-order kinetic plot, the linear evolutions of the molar mass with total monomer conversion, and the relatively low dispersity (Đ~1.55 of the resulting copolymers suggest that this cobalt complex provides some degree of control over the copolymerization of VAc and MAF-TBE. Compared to the previously investigated cobalt complex OMRP mediators having a fully oxygen-based first coordination sphere, this study emphasizes a few peculiarities of Co(SAL2: a lower ability to trap radical chains as compared to Co(acac2 and the absence of catalytic chain transfer reactions, which dominates polymerizations carried in the presence of 9-oxyphenalenone cobalt derivative.

t-Butyl group-substituted triphenylamine-containing orange-red fluorescent emitters for organic light-emitting diodes

Energy Technology Data Exchange (ETDEWEB)

Lee, Kum Hee; Kim, Chi Sik [Department of Chemistry, Sungkyunkwan University, Suwon, 440-746 (Korea, Republic of); Kim, Young Kwan, E-mail: kimyk@hongik.ac.kr [Department of Information Display, Hongik University, Seoul 121-791 (Korea, Republic of); Yoon, Seung Soo, E-mail: ssyoon@skku.edu [Department of Chemistry, Sungkyunkwan University, Suwon, 440-746 (Korea, Republic of)

2012-03-30

Efficient orange-red fluorescent compounds, 4-(dicyanomethylene)-2-adamantyl-6-(4-(N-(4-tert-butylphenyl) -N-(3,5-di-tert-butylphenyl)amino)benzene)vinyl-4H-pyran (DCATP) and 2,6-bis[4-(N-(4-tert-butylphenyl)-N-(3,5-di-tert-butylphenyl)amino)benzene] vinyl-4-(dicyanomethylene)-4H-pyran (BDCTP) containing the tert-butylated triphenylamine in donor moieties, were synthesized and characterized. In these red emitters, bulky groups, such as t-butyl group and adamantane were introduced to increase the steric hindrance between the red emitters. In particular, an efficient orange-red device containing the emitter DCATP as a dopant showed a luminous and power efficiency of 6.87 cd/A and 2.70 lm/W, respectively, at 20 mA/cm{sup 2} with the CIE coordinates of (0.48, 0.50) at 7.0 V. In addition, an efficient red organic light-emitting diode using BDCTP as a dopant exhibited a luminous and power efficiency of 2.30 cd/A and 1.31 lm/W, respectively, at 20 mA/cm{sup 2} and CIE coordinates of (0.61, 0.39). - Highlights: Black-Right-Pointing-Pointer Two orange-red emitters with t-butylated triphenylamine derivatives were studied. Black-Right-Pointing-Pointer We examine changes in electron D-A and electron D-A-D type in the terminal groups. Black-Right-Pointing-Pointer Electron D-A-D type material shows improved color chromaticity.

Egyptian Pancratium maritimum L. flowers as a source of anti-Alzheimer’s agents

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Maha Mohamed Soltan

2015-06-01

Full Text Available Elevation of acetylcholinesterase enzyme (AChE has been reported to be implicated in the etiology of Alzheimer disease (AD. One of the encouraged strategies to fight AD is the plant-derived inhibitors. Amaryllidaceae species are enriched source of alkaloids. The inhibitory properties of roots and bulbs of Pancratium maritimum L. against AChE have been previously reported. In the present study, the flowers of the wild Egyptian P. maritimum were subjected to screening assays to evaluate its potency as inhibitor to AChE. Besides, its antioxidant and cytotoxic properties were also addressed. The acetylcholinesterase inhibitory properties of P. maritimum; total extract and its alkaloid mixture were examined using Ellman’s assay. The direct antioxidant examination was carried out using DPPH assay whereas the indirect was monitored by the ability to protect Hepa1c1c7 cells against the induced cytotoxicity produced by tert-butyl hydroperoxide (TBHP. The cytotoxic effect of the total extract and crude alkaloid mixture was evaluated against the human liver hepatoma cell line (HepG2. P. maritimum flowers showed significant inhibitory activity against AChE. The potency of the alkaloid mixture, representing 5.0% of the flowers weight (IC50; 22.02 ± 0.59 μg/ml was about fourfold of its total extract (IC50; 97.67 ± 4.06 μg/ml. The total extract was able to protect about 33.4% of Hepa1c1c7 against the induced intoxication that carried by TBHP rather than the alkaloid mixture. Weak antioxidant and cytotoxic activities were recorded by both examined samples. Flowers of the Egyptian P. maritimum L. could be an enriched source of AChE inhibitors.

Inhibition of Suicidal Erythrocyte Death by Indirubin-3’-Monoxime

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Chunqiu Liu

2018-02-01

Full Text Available Background/Aims: Qing Dai is a prized traditional Chinese medicine whose major component, indirubin, and its derivative, indirubin-3’-monoxime (IDM, have inhibitory effects on the growth of many human tumor cells and pronounced anti-leukemic activities. However, the effects of IDM on mature human erythrocytes are unclear. This study aimed to evaluate the potential impact of IDM on erythrocytes and the mechanisms underlying that impact. Methods: Utilizing flow cytometry and confocal laser scanning microscopy, phosphatidylserine exposure at the cell surface was estimated by annexin V-fluorescein isothiocyanate (FITC. The relative cell size, expressed in arbitrary units, was evaluated by forward scatter in a flow cytometer. Fluo-3 fluorescence was used to bewrite changes in cytosolic Ca2+ activity, reactive oxygen species (ROS formation was assessed by 2,7-dichlorodihydrofluorescein diacetate (DCFH-DA fluorescence, and ceramide abundance was evaluated by FITC-conjugated specific antibodies. Results: The 24-h exposure of human erythrocytes to IDM (12 µM significantly decreased the percentage of annexin V-binding erythrocytes and the intracellular calcium concentration ([Ca2+]i. IDM (3-12 µM did not significantly modify the ceramide level or DCFH-DA fluorescence. Energy depletion (removal of glucose for 24 hours significantly increased annexin V binding and Fluo-3 fluorescence and diminished forward scatter, and these effects were significantly mitigated by IDM (12 µM. Moreover, the Ca2+ ionophore ionomycin (1 µM, 60 min and oxidative stress (30 min exposure to 0.05 mM tert-butyl hydroperoxide, t-BHP similarly triggered eryptosis, which was also significantly suppressed by IDM. Conclusions: IDM is a novel inhibitor of suicidal erythrocyte death following ionomycin treatment, t-BHP treatment and energy depletion. Thus, IDM may counteract anemia and impairment of microcirculation, at least in part, by inhibition of Ca2+ entry into erythrocytes.

Ground-State Distortion in N-Acyl-tert-butyl-carbamates (Boc) and N-Acyl-tosylamides (Ts): Twisted Amides of Relevance to Amide N-C Cross-Coupling.

Science.gov (United States)

Szostak, Roman; Shi, Shicheng; Meng, Guangrong; Lalancette, Roger; Szostak, Michal

2016-09-02

Amide N-C(O) bonds are generally unreactive in cross-coupling reactions employing low-valent transition metals due to nN → π*C═O resonance. Herein we demonstrate that N-acyl-tert-butyl-carbamates (Boc) and N-acyl-tosylamides (Ts), two classes of acyclic amides that have recently enabled the development of elusive amide bond N-C cross-coupling reactions with organometallic reagents, are intrinsically twisted around the N-C(O) axis. The data have important implications for the design of new amide cross-coupling reactions with the N-C(O) amide bond cleavage as a key step.

(tert-Butylimidobis(η5-cyclopentadienylpyridinezirconium(IV

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Katharina Kaleta

2010-09-01

Full Text Available The title compound, [Zr(C5H52(C4H9N(C5H5N], was obtained from the reaction of (C5H52Zr(py(η2-Me3SiC2SiMe3 (py is pyridine and tBuN=C=NtBu alongside the formation of (C5H52Zr(CNtBu(η2-Me3SiC2SiMe3. The zirconium atom is coordinated in a distorted tetrahedral geometry by two cyclopentadienyl ligands, a pyridine ligand, and a tert-butylimido ligand via a Zr=N double bond. The tert-butyl group is disordered over two positions in a 0.634 (5:0.366 (5 ratio.

Effect of Brewing Duration on the Antioxidant and Hepatoprotective Abilities of Tea Phenolic and Alkaloid Compounds in a t-BHP Oxidative Stress-Induced Rat Hepatocyte Model

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Laura Braud

2015-08-01

Full Text Available Tea is an interesting source of antioxidants capable of counteracting the oxidative stress implicated in liver diseases. We investigated the impact of antioxidant molecules provided by a mixture of teas’ leaves (green, oolong, pu-erh after different infusion durations in the prevention of oxidative stress in isolated rat hepatocytes, by comparison with pure epigallocatechin-3-gallate (EGCG, the main representative of tea catechins. Dried aqueous tea extracts (ATE obtained after 5, 15 and 30 min infusion time were characterized for total polyphenols (gallic acid equivalent, catechins, gallic acid and caffeine (HPLC-DAD/ESI-MS contents, and for scavenging ability against 2,2-diphenyl-1-picrylhydrazyl free radical. Hepatoprotection was evaluated through hepatocyte viability tests using tert-butyl hydroperoxide as a stress inducer, (3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide, neutral red uptake, real-time cellular impedance and mitochondrial function tests. We showed that a 5-min incubation time is sufficient for an optimal bioaccessibility of tea compounds with the highest antioxidative ability, which decreases for longer durations. A 4-h pretreatment of cells with ATE significantly prevented cell death by regulating reactive oxygen species production and maintaining mitochondrial integrity. Pure EGCG, at doses similar in ATE (5–12 µM, was inefficient, suggesting a plausible synergy of several water-soluble tea compounds to explain the ATE beneficial effects.

In situ 1H NMR studies of high-temperature nitroxide-mediated polymerization of n-butyl acrylate

NARCIS (Netherlands)

Hlalele, L.; Klumperman, L.

2011-01-01

This paper presents results on the independence of the rate of polymerization of n-butyl acrylate (n-BA) toward initial concentration of the alkoxyamine initiator. The alkoxyamine, 2-methyl-2-[N-tert-butyl-N-(1-diethoxyphosphoryl-2,2-dimethylpropyl)aminooxy]propionic acid (MAMA-DEPN), was used to

Electrochemical and Spin-Trapping Properties of para-substituted α-Phenyl-N-tert-butyl Nitrones

International Nuclear Information System (INIS)

Rosselin, Marie; Tuccio, Béatrice; Pério, Pierre; Villamena, Frederick A.; Fabre, Paul-Louis; Durand, Grégory

2016-01-01

Nitrones are known both as therapeutic antioxidants and efficient spin-traps. In this work, the redox behavior of various para-substituted α-phenyl-N-tert-butyl nitrones (PBN) was studied by cyclic voltammetry. The polar effect of the substituents was found to correlate with the electrochemical properties of the nitronyl function. Compounds bearing an electron-withdrawing group were more easily reduced than those having an electron-donating group and an opposite trend was observed for the oxidation. Ease of oxidation was also computationally rationalized using DFT approach showing increased ease of oxidation with electron donating functionalities. Since electrochemical properties of nitrones are known to correlate with biological properties, this work provides insights in the design of potent nitrone antioxidants. Using cyclic voltammetry the relative rate of superoxide trapping by nitrones was investigated and compared to the classical antioxidant BHT. The determination of the relative rate of phenyl radical trapping was also carried out but showed no clear correlation with the nature of the substituents. This indicates the absence of a polar effect in agreement with previous data and further supports the intermediate nature, that is, non- or weakly nucleophile, of phenyl radical. On the contrary kinetics of hydroxymethyl radical trapping was found to correlate with the nature of the substituents, demonstrating the nucleophilic nature of its addition onto nitrones.

Solvent extraction of technetium from alkaline waste media using bis-4,4'(5')[(tert-butyl)cyclohexano]-18-crown-6

International Nuclear Information System (INIS)

Bonnesen, P.V.; Presley, D.J.; Moyer, B.A.

1995-01-01

The crown ether bis-4,4'(5')[(tert-butyl)cyclohexano]-18-crown-6 can be utilized in a solvent-extraction process for the removal of technetium as pertechnetate ion, TcO 4 - from solutions simulating highly radioactive alkaline defense wastes (''tank wastes'') stored at several sites in the United States. The process employs non-halogenated and non-volatile diluents and modifiers and includes an efficient stripping procedure using only water. More than 95% of the pertechnetate present at 6 x 10 -5 M in Melton Valley (Oak Ridge, TN) and Hanford (Washington) tank-waste simulants was removed following two cross-current extraction contacts using 0.02 M bis-4,4'(5')[(tertbutyl)cyclohexano]- 18-crown-6 in 2:1 vol/vol TBP/Isopar reg-sign M diluent at 25 C. Similarly, for both simulants, more than 98% of the pertechnetate contained in the solvent was back-extracted following two cross-current stripping contacts using deionized water

Free radicals in an Adamantane matrix. XI. Electron paramagnetic resonance study of conformations in the β-halo-tert-butyl radicals

International Nuclear Information System (INIS)

Lloyd, R.V.; Wood, D.E.

1975-01-01

The β-halo-tert-butyl radicals were prepared by x-irradiation of the corresponding isobutyl halides in an adamantane matrix at 77 0 K and their conformations were determined by analysis of their EPR spectra. The radicals are nonplanar at the radical site, the fluoro and chloro radicals trans eclipsed and the bromo and iodo radicals gauche staggered with respect to the relative orientation of the carbon halogen bond and the direction of the singly occupied orbital. Vibration-rotation motions about the favored conformation are much larger for the fluoro radical than for the others. The rate of interconversion of the inequivalent methylene protons is approximately 1.5 x 10 9 sec -1 for the bromo radical at 202 0 K while it is too slow to measure for the iodo radical at the same temperature. The barrier to interconversion has a lower limit of 3 kcal/mol for the bromo radical and higher than that for the iodo radical. The halogen and proton hfsc in gauss and the g values for the XCH 2 C(CH 3 ) 2 radicals are: 19 F = 103.7, CH 2 = 10.4, CH 3 = 23.3, g = 2.0030 at 214 K; 35 Cl = 19.5, CH 2 = 6.3, CH 3 = 21.1, g = 2.0042 at 215 K; 81 Br = 6.7, CH 2 = 21.4, 42.7, CH 3 = 21.4, g = 2.0010 at 202 K; 127 I = 7.0, CH 2 = 21.9, 43.8, CH 3 = 21.9, g = 2.0009 at 208 K. The fluoro radical decays to nonradical products above 318 0 K, the chloro radical converts to 2-methyl allyl radical above 306 0 K, the bromo radical converts to tert-butyl radical by exchange with a matrix proton (or deuteron) at 209 0 K as does the iodo radical above 225 0 K. Photolysis with a Xe lamp converts the bromo and iodo radicals to nonradical products in less than the experimental time constant of 0.3 sec. The hypothesis is put forward that the nonplanarity and high barrier to rotation observed explain the retention of stereochemical configuration in reactions involving β-chloro, β-bromo, and β-iodo alkyl radicals. (auth)

Side-by-Side Comparison of Hydroperoxide and Corresponding Alcohol as Hydrogen-Bond Donors

DEFF Research Database (Denmark)

Møller, Kristian Holten; Tram, Camilla Mia; Kjærgaard, Henrik Grum

2017-01-01

tert-butanol (t-BuOH), with dimethyl ether (DME) as the hydrogen-bond acceptor. Using a combination of Fourier-transform infrared spectroscopy and quantum chemical calculations, we compare the strength of the OH-O hydrogen bond and the total strength of complexation. We find that, both in terms...... results, we find that the hydroperoxide complex is stabilized by ∼4 kJ/mol (Gibbs free energy) more than the alcohol complex. Measured red shifts show the same trend in hydrogen-bond strength with trimethylamine (N acceptor atom) and dimethyl sulfide (S acceptor atom) as the hydrogen-bond acceptors....

Methyl tert-butyl ether biodegradation by indigenous aquifer microorganisms under natural and artificial oxic conditions

Science.gov (United States)

Landmeyer, J.E.; Chapelle, F.H.; Herlong, H.H.; Bradley, P.M.

2001-01-01

Microbial communities indigenous to a shallow groundwater system near Beaufort, SC, degraded milligram per liter concentrations of methyl tert-butyl ether (MTBE) under natural and artificial oxic conditions. Significant MTBE biodegradation was observed where anoxic, MTBE-contaminated groundwater discharged to a concrete-lined ditch. In the anoxic groundwater adjacent to the ditch, concentrations of MTBE were > 1 mg/L. Where groundwater discharge occurs, dissolved oxygen (DO) concentrations beneath the ditch exceeded 1.0 mg/L to a depth of 1.5 m, and MTBE concentrations decreased to CO2 in laboratory liquid culture studies, with no accumulation of intermediate compounds. Upgradient of the ditch in the anoxic, MTBE and BTEX-contaminated aquifer, addition of a soluble oxygen release compound resulted in oxic conditions and rapid MTBE biodegradation by indigenous microorganisms. In an observation well located closest to the oxygen addition area, DO concentrations increased from 0.4 to 12 mg/L in <60 days and MTBE concentrations decreased from 20 to 3 mg/L. In the same time period at a downgradient observation well, DO increased from <0.2 to 2 mg/L and MTBE concentrations decreased from 30 to <5 mg/L. These results indicate that microorganisms indigenous to the groundwater system at this site can degrade milligram per liter concentrations of MTBE under natural and artificial oxic conditions.

Crystal structure of trans-N,N′-bis(3,5-di-tert-butyl-2-hydroxyphenyloxamide methanol monosolvate

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Miguel-Ángel Velázquez-Carmona

2016-07-01

Full Text Available The here crystallized oxamide was previously characterized as an unsolvated species [Jímenez-Pérez et al. (2000. J. Organomet. Chem. 614–615, 283–293], and is now reported with methanol as a solvent of crystallization, C30H44N2O4·CH3OH, in a different space group. The introduction of the solvent influences neither the molecular symmetry of the oxamide, which remains centrosymmetric, nor the molecular conformation. However, the unsolvated molecule crystallized as an ordered system, while many parts of the solvated crystal are disordered. The hydroxy group in the oxamide is disordered over two chemically equivalent positions, with occupancies 0.696 (4:0.304 (4; one tert-butyl group is disordered by rotation about the C—C bond, and was modelled with three sites for each methyl group, each one with occupancy 1/3. Finally, the methanol solvent, which lies on a twofold axis, is disordered by symmetry. The disorder affecting hydroxy groups and the solvent of crystallization allows the formation of numerous supramolecular motifs using four hydrogen bonds, with N—H and O—H groups as donors and the oxamide and methanol molecule as acceptors.

Plasma antioxidant capacity, sexual and thyroid hormones levels, sperm quantity and quality parameters in stressed male rats received nano-particle of selenium

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M Rezaeian-Tabrizi

2017-01-01

Full Text Available Objective: To evaluate the effects of nano-particle of selenium (nSe on plasma antioxidant capacity, sexual and thyroid hormones and spermatogenesis in male rats exposed to oxidative stress.Methods: Forty rats were randomly divided into four treatments with ten replicates. Treatment groups were: C, the control group received normal saline as gavage and injection (i.p.; OS, received tert-butyl hydroperoxide (0.2 mmol/kg body weight for inducing oxidative stress; nSe, received nSe (0.3 mg/kg body weight as gavage, and OS+nSe, received tert-butyl hydroperoxide and nSe. All groups were treated for 28 d and administrations were done each 48 h.Results: Oxidative stress decreased and gavage of nSe to stressed rats increased the antioxidant capacity and activities (P0.05 between rats exposed to oxidative stress and those in the control group for sperm quantity and quality. Gavage of nSe to stressed rats had no effect (P>0.05 on the sperm parameters, except increased viability and progressive percentages.Conclusions: Nano-particle of Selenium administration in stressed rats could ameliorate the negative effects of oxidative stress on the antioxidant capacity and activities, but not on the quantity and quality parameters of sperm.

Improving the Safety of Lithium-Ion Battery via a Redox Shuttle Additive 2,5-Di- tert-butyl-1,4-bis(2-methoxyethoxy)benzene (DBBB).

Science.gov (United States)

Leonet, Olatz; Colmenares, Luis C; Kvasha, Andriy; Oyarbide, Mikel; Mainar, Aroa R; Glossmann, Tobias; Blázquez, J Alberto; Zhang, Zhengcheng

2018-03-21

2,5-Di- tert-butyl-1,4-bis(2-methoxyethoxy)benzene (DBBB) is studied as a redox shuttle additive for overcharge protection for a 1.5 Ah graphite/C-LFP lithium-ion pouch cell for the first time. The electrochemical performance demonstrated that the protecting additive remains inert during the extended standard cycling for 4000 cycles. When a 100% overcharge is introduced in the charging protocol, the baseline cell fails rapidly during the first abusive event, whereas the cell containing DBBB additive withstands 700 overcharge cycles with 87% capacity retention and no gas evolution or cell swelling was observed. It is the first time the effectiveness of the DBBB as overcharge protection additive in a large pouch cell format is demonstrated.

Sulfated polyborate: A mild, efficient catalyst for synthesis of N-tert ...

Indian Academy of Sciences (India)

Rapid, efficient and inexpensive method for synthesis of N-tert-butyl/N-trityl protected amides via Ritter reaction of nitriles with tertiary alcohols in the presence of a sulfated polyborate catalyst under solvent-free conditions is described. The catalyst has the advantage of Lewis as well as Bronsted acidity and recyclability ...

Spin-crossover in an iron(III)-bispidine-alkylperoxide system.

Science.gov (United States)

Bautz, Jochen; Comba, Peter; Que, Lawrence

2006-09-04

The iron(II) complex of a tetradentate bispidine ligand with two tertiary amines and two pyridine groups (L = dimethyl [3,7-dimethyl-9,9'-dihydroxy-2,4-di-(2-pyridyl)-3,7-diazabicyclo nonan-1,5-dicaboxylate]) is oxidized with tert-butyl hydroperoxide to the corresponding end-on tert-butylperoxo complex [Fe(III)(L)(OOtBu)(X)]n+ (X = solvent, anion). UV-vis, resonance Raman, and EPR spectroscopy, as a function of the solvent, show that this is a spin-crossover compound. The experimentally observed Raman vibrations for both low-spin and high-spin isomers are in good agreement with those computed by DFT.

[Biodegradation of methyl tert-butyl ether by stabilized immobilized Methylibium petroleiphilum PM1 cells and its biodegradation kinetics analysis].

Science.gov (United States)

Cheng, Zhuo-wei; Fu, Ling-xiao; Jiang, Yi-feng; Chen, Jian-meng; Zhang, Rong

2011-05-01

Methylibium petroleiphilum PM1, which is capable of degrading methyl tert-butyl ether (MTBE) , was immobilized in calcium alginate gel beads. Several methods were explored to increase the strength of these gel beads. The central composite design analysis indicated that the introduction of 0.2 mol x L(-1) Ca2+ into the crosslinking solution, 1.38 mmol x L(-1) Ca2+ into the growth medium and 0.1% polyethyleneimine (PEI) as the chemical crosslinking agent could increase the stability of the Ca-alginate gel beads with no loss of biodegradation activity. The stabilized immobilized cells could be used 400 h continuously with no breakage and no bioactivity loss. Examination of scanning electron microscope demonstrated that a membrane surrounding the gel beads was formed and the cells could grow and breed well in the stabilized calcium alginate gel beads. Kinetic analysis of the gel bead-degradation indicated that the rate-limiting step was biochemical process instead of intraparticle diffusion process. The diameter of 3 mm affected the biodegradability less while high concentration of PEI induced much more serious mass transfer restraint.

Adiabatic compressibility of pseudo-binary aqueous solutions of tert-butyl alcohol and dimethylsulfoxide as a result of ultrasonic investigations

International Nuclear Information System (INIS)

Miecznik, Piotr; Kaczmarek, Milena

2006-01-01

The tert-butyl alcohol (TBA) and dimethyl sulfoxide (DMSO) are two small molecules geometrically very similar, but having different polar groups. Taking into account the intermolecular interactions in the TBA/H 2 O and DMSO/H 2 O systems, especially in the water-rich region of concentration, the ultrasonic speeds (high accuracy resonance method at the frequency 7.5 MHz) and densities in pseudo-binary mixtures of the system: (TBA + H 2 O + DMSO) with the ratio (TBA + DMSO)/H 2 O = 1/25 have been measured. From these data, various thermodynamical parameters such as adiabatic compressibility, molar volume, thermal expansivity, and the deviation from reference system have been calculated. In addition, the isobaric molar heat capacity to convert adiabatic compressibility to the isothermal one has been measured. All these parameters have been discussed to explain solute-solvent and solute-solute interactions, especially the effect of the complexation process between TBA and DMSO molecules. The composition dependence of these deviations functions was interpreted in the light of the mixing schemes in the aqueous solutions of TBA and DMSO

Adiabatic compressibility of pseudo-binary aqueous solutions of tert-butyl alcohol and dimethylsulfoxide as a result of ultrasonic investigations

Energy Technology Data Exchange (ETDEWEB)

Miecznik, Piotr [Institute of Acoustics, Adam Mickiewicz University, Umultowska 85, PL-61-614 Poznan (Poland)]. E-mail: miecznik@main.amu.edu.pl; Kaczmarek, Milena [Institute of Acoustics, Adam Mickiewicz University, Umultowska 85, PL-61-614 Poznan (Poland)

2006-11-15

The tert-butyl alcohol (TBA) and dimethyl sulfoxide (DMSO) are two small molecules geometrically very similar, but having different polar groups. Taking into account the intermolecular interactions in the TBA/H{sub 2}O and DMSO/H{sub 2}O systems, especially in the water-rich region of concentration, the ultrasonic speeds (high accuracy resonance method at the frequency 7.5 MHz) and densities in pseudo-binary mixtures of the system: (TBA + H{sub 2}O + DMSO) with the ratio (TBA + DMSO)/H{sub 2}O = 1/25 have been measured. From these data, various thermodynamical parameters such as adiabatic compressibility, molar volume, thermal expansivity, and the deviation from reference system have been calculated. In addition, the isobaric molar heat capacity to convert adiabatic compressibility to the isothermal one has been measured. All these parameters have been discussed to explain solute-solvent and solute-solute interactions, especially the effect of the complexation process between TBA and DMSO molecules. The composition dependence of these deviations functions was interpreted in the light of the mixing schemes in the aqueous solutions of TBA and DMSO.

Synthesis, structural characterization and theoretical studies of a new Schiff base 4-(((3-(tert-Butyl)-(1-phenyl)pyrazol-5-yl) imino)methyl)phenol

Science.gov (United States)

Cuenú, Fernando; Londoño-Salazar, Jennifer; Torres, John Eduard; Abonia, Rodrigo; D'Vries, Richard F.

2018-01-01

4-(((3-(tert-Butyl)-(1-phenyl)pyrazol-5-yl)imino)methyl)phenol (4-OHFPz) was synthesized and characterized by FT-IR, MS, NMR, and single-crystal X-ray diffraction. Optimization of molecular geometry, vibrational frequencies, and chemical shifts were calculated by using the methods of density functional theory (DFT) with B3LYP and B3PW91 as functionals and Hartree-Fock with 6-311G++(d,p) as basis set using the GAUSSIAN 09 program package. With the VEDA 4 software, the vibrational frequencies were assigned in terms of the potential energy distribution (PED). The equilibrium geometries calculated by all methods were compared with X-ray diffraction results, indicating that the theoretical results matches well with the experimental ones. The data obtained from the vibrational analysis and the calculated NMR are consistent with the experimental spectra.

Lico A Enhances Nrf2-Mediated Defense Mechanisms against t-BHP-Induced Oxidative Stress and Cell Death via Akt and ERK Activation in RAW 264.7 Cells

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Hongming Lv

2015-01-01

Full Text Available Licochalcone A (Lico A exhibits various biological properties, including anti-inflammatory and antioxidant activities. In this study, we investigated the antioxidative potential and mechanisms of Lico A against tert-butyl hydroperoxide- (t-BHP- induced oxidative damage in RAW 264.7 cells. Our results indicated that Lico A significantly inhibited t-BHP-induced cytotoxicity, apoptosis, and reactive oxygen species (ROS generation and reduced glutathione (GSH depletion but increased the glutamate-cysteine ligase modifier (GCLM subunit and the glutamate-cysteine ligase catalytic (GCLC subunit genes expression. Additionally, Lico A dramatically upregulated the antioxidant enzyme heme oxygenase 1 (HO-1 and nuclear factor erythroid 2-related factor 2 (Nrf2, which were associated with inducing Nrf2 nuclear translocation, decreasing Keap1 protein expression and increasing antioxidant response element (ARE promoter activity. Lico A also obviously induced the activation of serine/threonine kinase (Akt and extracellular signal-regulated kinase (ERK, but PI3K/Akt and ERK inhibitors treatment displayed clearly decreased levels of LicoA-induced Nrf2 nuclear translocation and HO-1 expression, respectively. Furthermore, Lico A treatment markedly attenuated t-BHP-induced oxidative damage, which was reduced by treatment with PI3K/Akt, ERK, and HO-1 inhibitors. Therefore, Lico A might have a protective role against t-BHP-induced cytotoxicity by modulating HO-1 and by scavenging ROS via the activation of the PI3K/Akt and ERK/Nrf2 signaling pathways.

Enhancement of the Biodegradability of Methyl tert- Butyl Ether (MTBE by Advanced Oxidation

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Mehraban Sadeghi

2006-06-01

Full Text Available The effectiveness of ozone treatment for improving the biodegradability of recalcitrant pollutants has been proved by investigating the ozonation reaction of Methyl tert-Butyl Ether (MTBE as a bioresistant gasoline oxygenate. Laboratory scale experiments have been carried out at room temperature by bubbling for 120 minutes ozonated air (3.4 ppm/min into 3 liter of an alkaline (pH=11.5 aqueous solution (100 mg/L of MTBE. The experimental results indicated that during the ozonation, complete MTBE degradation occurs in 100 minutes and after this time, ozone consumption goes on very slowly. At the end of the ozonation, after 100 minutes, the initial value of COD (256 mg O2/L is 98 and corresponds to a relative removal of about 62%. As for MTBE solution biodegradability expressed as (BOD5 / (COD ratio, during the first 90 minutes, its value regularly increases from lowest 0.01 up to a maximum of 0.68 that corresponds to an ozone consumption of 1.25 mg per each mg of COD initially present in the solution. The research showed that partial degradation of MTBE in the advanced oxidation processes results an increase in its biological degradation. But more oxidation results lower  (BOD5 / (COD ratio. Also the research showed that for idealization of the chemical oxidation conditions of MTBE, it needs to decrease COD to 46-68% before the biological degradation. The experimental results for determining the rate of MTBE removal due to stripping showed that about 14% of MTBE strips out after an hour of sparging with oxygen gas. The fraction of MTBE oxidized and/or striped increases to about 28% (in pH=7 and 70% (in pH=11.5 with ozonation over the same time period.

tert-Butyl 4-carbamoyl-3-methoxyimino-4-methylpiperidine-1-carboxylate

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Yucheng Wang

2008-12-01

Full Text Available The title compound, C13H23N3O4, was prepared starting from ethyl N-benzyl-3-oxopiperidine-4-carboxylate through a nine-step reaction, including hydrogenation, Boc (tert-butoxycarbonyl protection, methylation, oximation, hydrolysis, esterification and ammonolysis. In the crystal structure, molecules are linked by intermolecular N—H...O hydrogen bonds to form a porous three-dimensional network with solvent-free hydrophobic channels extending along the c axis.

Vibrational frequency analysis, FT-IR, DFT and M06-2X studies on tert-Butyl N-(thiophen-2yl)carbamate

Science.gov (United States)

Sert, Yusuf; Singer, L. M.; Findlater, M.; Doğan, Hatice; Çırak, Ç.

2014-07-01

In this study, the experimental and theoretical vibrational frequencies of a newly synthesized tert-Butyl N-(thiophen-2yl)carbamate have been investigated. The experimental FT-IR (4000-400 cm-1) spectrum of the molecule in the solid phase have been recorded. The theoretical vibrational frequencies and optimized geometric parameters (bond lengths and bond angles) have been calculated by using density functional theory (DFT/B3LYP: Becke, 3-parameter, Lee-Yang-Parr) and DFT/M06-2X (the highly parametrized, empirical exchange correlation function) quantum chemical methods with the 6-311++G(d,p) basis set by Gaussian 09W software, for the first time. The vibrational frequencies have been assigned using potential energy distribution (PED) analysis by using VEDA 4 software. The computational optimized geometric parameters and vibrational frequencies have been found to be in good agreement with the corresponding experimental data, and with related literature results. In addition, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energies and the other related molecular energy values have been calculated and are depicted.

Electrochemical oxidation of 3,5-di-tert-butylcatechol: Synthesis and characterization of the formed ortho-benzoquinhydrone derivative

International Nuclear Information System (INIS)

Nematollahi, D.; Shayani-Jam, H.

2006-01-01

Electrochemical oxidation of 3,5-di-tert-butylcatechol (1) has been studied in ethanol/water mixtures by means of cyclic voltammetry and controlled-potential coulometry. The results revealed that 3,5-di-tert-butyl-1,2-benenzoquinone (2) derived from oxidation of 3,5-di-tert-butylcatechol participate in noncovalently linked interactions with 1 converted to an ortho-benzoquinhydrone (3). The structure of 3 was characterized by MS, IR, 1 H NMR and 13 C NMR. The 1 H NMR studies reveal that the benzoquinhydrone complex 3 is stabilized by one H-bonding interaction. In this work we derived a novel ortho-bezoquinhydrone type complex (3) based on electrochemical oxidation of 3,5-di-tert-butylcatechol at carbon electrode in an undivided cell

High turnover catalysis of water oxidation by Mn(II) complexes of monoanionic pentadentate ligands

DEFF Research Database (Denmark)

Seidler-Egdal, Rune Kirk; Nielsen, Anne; Bond, Andrew

2011-01-01

-pyridylmethyl)ethane-1,2-diamine (bcbpen(-)), show the presence of a mixture of closely related Mn(II) species, assigned to the mono, di-, tri- and poly-cationic complexes [Mn(II)(L)(H(2)O)](n)(n+), L = mcbpen(-) or bcbpen(-) with n = 1, 2, 3, etc. In solution, these complexes are reversibly oxidized by tert......:1 reaction of TBHP with [Mn] is rate determining and the resultant species is proposed to be the mononuclear, catalytically competent, [Mn(IV)(O)(mcbpen)](+). At very close m/z values [Mn(III)(OH)(mcbpen)](+), [Mn(2)(III/IV)(O)(2)(mcbpen)(2)](+) and [Mn(IV)(2)(O)(2)(mcbpen)(2)](2+) are detected by ESI MS......-butyl hydrogen peroxide (TBHP), (NH(4))(2)[Ce(NO(3))(6)], Ce(ClO(4))(4), oxone and [Ru(bipy)(3)](3+) to form metastable (t(½) = min to h) higher valent (hydr)oxide species, showing a collective maximum absorbance at 430 nm. The same species can be produced by [Ru(bipy)(3)](2+)-mediated photooxidization...

High Turnover Catalysis of Water Oxidation by Mn(II) complexes of Monoanionic Pentadentate Ligands

DEFF Research Database (Denmark)

Seidler-Egdal, Rune Kirk; Nielsen, Anne; Bond, Andrew

2011-01-01

-pyridylmethyl)ethane-1,2-diamine (bcbpen−), show the presence of a mixture of closely related Mn(II) species, assigned to the mono, di-, tri- and poly-cationic complexes [MnII(L)(H2O)]nn+, L = mcbpen− or bcbpen− with n = 1, 2, 3, etc. In solution, these complexes are reversibly oxidized by tert-butyl hydrogen...... determining and the resultant species is proposed to be the mononuclear, catalytically competent, [MnIV(O)(mcbpen)]+. At very close m/z values [MnIII(OH)(mcbpen)]+, [Mn2III/IV(O)2(mcbpen)2]+ and [MnIV2(O)2(mcbpen)2]2+are detected by ESI MS and CE when the concentration of TBHP is comparable to or lower than...... peroxide (TBHP), (NH4)2[Ce(NO3)6], Ce(ClO4)4, oxone and [Ru(bipy)3]3+ to form metastable (t½ = min to h) higher valent (hydr)oxide species, showing a collective maximum absorbance at 430 nm. The same species can be produced by [Ru(bipy)3]2+-mediated photooxidization in the presence of an electron acceptor...

Development of natural rubber membranes for separation of methyl tert-butyl ether and methanol

International Nuclear Information System (INIS)

Nur Azrini Ramlee; Ghazali Mohd Nawawi; Khairul Zaman Dahlan

2010-01-01

As a new commercial process, membrane separation raises significant expectations in the process plant of the future and therefore this research was being initiated to develop and characterize pervaporation membrane based on natural rubber (NR). Natural Rubber SMR-L grade which was supplied by Malaysia Rubber Research Institute (MRRI) was used for the development of the membranes via interpenetrating polymer network (IPN) techniques. Polystyrene (PS) was used to modify the natural rubber to further improve their mechanical and chemical properties. The membranes were prepared with various blend ratios of natural rubber, polystyrene and divinyl benzene as cross linker with constant 1 % of dicumyl peroxide as the initiator. The developed membranes were then characterized to study the functional group presence, membranes morphology, crosslink density, tear strength, adsorption of the membranes and pervaporation separation of Methyl-Tert-Butyl-Ether (MTBE) and Methanol. Pervaporation process was conducted by using varies of MTBE concentration 10, 30, 50 and 70 wt % and at differ operation temperature, 25 degree Celsius and 55 degree Celsius. Separation performance of IPN NR/ PS membranes were based on the presented permeation flux and separation factor. Examination through Fourier Transform Infrared Spectroscopy (FTIR), determined crosslink density and tear strength, 6 series of IPN NR/ PS membranes were successfully developed using natural rubber. Observation from Scanning Electron Microscopy (SEM) showed that the membranes were dense and appropriated for the pervaporation process application. From the pervaporation of MTBE and Methanol, IPN NR/ PS membranes of series D4N30 shown low permeation flux of MTBE but high separation factor while D2N70 membranes was vice versa for both temperature of 25 degree Celsius and 55 degree Celsius. (author)

Method detection limit determination and application of a convenient headspace analysis method for methyl tert-butyl ether in water.

Science.gov (United States)

O'Neill, Dennis T; Rochette, Elizabeth A; Ramsey, Philip J

2002-11-15

Methyl tert-butyl ether (MTBE) is a common groundwater contaminant, introduced to the environment by leaking petroleum storage tanks, urban runoff, and motorized watercraft. In this study. a simplified (static) headspace analysis method was adapted for determination of MTBE in water samples and soil water extracts. The MDL of the headspace method was calculated to be 2.0 microg L(-1) by the EPA single-concentration design method(1) and 1.2 microg L(-1) by a calibration method developed by Hubaux and Vos (Hubaux, A.; Vos, G. Anal. Chem. 1970,42, 849-855). The MDL calculated with the Hubaux and Vos method was favored because it considers both a true positive and a false positive. The static headspace method was applied to analysis of a tap water sample and a monitoring well sample from a gasoline service station, a river sample, and aqueous extracts from soil excavated during removal of a leaking underground storage tank (LUST). The water samples examined in this study had MTTBE concentrations ranging from 6 to 19 microg L(-1). Aqueous extracts of a soil sample taken from the LUST site had 8 microg L(-1) MTBE.

Assessing soil ecotoxicity of methyl tert-butyl ether using earthworm bioassay; closed soil microcosm test for volatile organic compounds

International Nuclear Information System (INIS)

An, Youn-Joo

2005-01-01

An earthworm bioassay was conducted to assess ecotoxicity in methyl tert-butyl ether (MTBE)-amended soils. Ecotoxicity of MTBE to earthworms was evaluated by a paper contact method, natural field soil test, and an OECD artificial soil test. All tests were conducted in closed systems to prevent volatilization of MTBE out of test units. Test earthworm species were Perionyx excavatus and Eisenia andrei. Mortality and abnormal morphology of earthworms exposed to different concentrations of MTBE were examined. MTBE was toxic to both earthworm species and the severity of response increased with increasing MTBE concentrations. Perionyx excavatus was more sensitive to MTBE than Eisenia andrei in filter papers and two different types of soils. MTBE toxicity was more severe in OECD artificial soils than in field soils, possibly due to the burrowing behavior of earthworms into artificial soils. The present study demonstrated that ecotoxicity of volatile organic compounds such as MTBE can be assessed using an earthworm bioassay in closed soil microcosm with short-term exposure duration. - Earthworm bioassay can be a good protocol to assess soil ecotoxicity of volatile organic compounds such as MTBE

A Study of the Curing and Flammability Properties of Bisphenol A Epoxy Diacrylate Resin Utilizing a Novel Flame Retardant Monomer, bis[di-acryloyloxyethyl]-p-tert-butyl-phenyl Phosphate

Directory of Open Access Journals (Sweden)

Syang-Peng Rwei

2017-02-01

Full Text Available A UV-curable, flame-retardant monomer, DAPP (bis[di-acryloyloxyethyl]-p-tert-butyl-phenyl-phosphate, was synthesized based on BPDCP (4-tert-butylphenyl-dichloro phosphate and HEA (2-hydroxy ethyl acrylate. DAPP was blended with regular bisphenol A epoxy acrylate (BAEA in various ratios to yield various phosphorus contents. The TGA-IR (thermogravimetric analyzer interface with an infrared spectrometer results demonstrate that compounding 30 mol % DAPP with BAEA significantly reduced the amount of released CO gas. In contrast, the peak intensity of CO2 is independent of phosphorus content. The limiting oxygen index (LOI, reaching the saturated value of 26, and the heat release rate (HRR measured using a cone-calorimeter, 156.43 KW/m2, confirm the saturation point when 30 mol % DAPP was compounded into BAEA. A study of the kinetics of pyrolysis reveals that Ea decreases as the phosphorus content increases. Both the TGA-IR and pyrolysis results reveal that the phosphorus compound DAPP is easily decomposed during the initial stage of burning to form an insulating layer, which inhibits further burning of the resin and the consequent release of other flammable gases.

Isolation of an oxomanganese(V) porphyrin intermediate in the reaction of a manganese(III) porphyrin complex and H2O2 in aqueous solution.

Science.gov (United States)

Nam, Wonwoo; Kim, Inwoo; Lim, Mi Hee; Choi, Hye Jin; Lee, Je Seung; Jang, Ho G

2002-05-03

The reaction of [Mn(TF(4)TMAP)](CF(3)SO(3))(5) (TF(4)TMAP=meso-tetrakis(2,3,5,6-tetrafluoro-N,N,N-trimethyl-4-aniliniumyl)porphinato dianion) with H(2)O(2) (2 equiv) at pH 10.5 and 0 degrees C yielded an oxomanganese(V) porphyrin complex 1 in aqueous solution, whereas an oxomanganese(IV) porphyrin complex 2 was generated in the reactions of tert-alkyl hydroperoxides such as tert-butyl hydroperoxide and 2-methyl-1-phenyl-2-propyl hydroperoxide. Complex 1 was capable of epoxidizing olefins and exchanging its oxygen with H(2) (18)O, whereas 2 did not epoxidize olefins. From the reactions of [Mn(TF(4)TMAP)](5+) with various oxidants in the pH range 3-11, the O-O bond cleavage of hydroperoxides was found to be sensitive to the hydroperoxide substituent and the pH of the reaction solution. Whereas the O-O bond of hydroperoxides containing an electron-donating tert-alkyl group is cleaved homolytically, an electron-withdrawing substituent such as an acyl group in m-chloroperoxybenzoic acid (m-CPBA) facilitates O-O bond heterolysis. The mechanism of the O-O bond cleavage of H(2)O(2) depends on the pH of the reaction solution: O-O bond homolysis prevails at low pH and O-O bond heterolysis becomes a predominant pathway at high pH. The effect of pH on (18)O incorporation from H(2) (18)O into oxygenated products was examined over a wide pH range, by carrying out the epoxidation of carbamazepine (CBZ) with [Mn(TF(4)TMAP)](5+) and KHSO(5) in buffered H(2) (18)O solutions. A high proportion of (18)O was incorporated into the CBZ-10,11-oxide product at all pH values but this proportion was not affected significantly by the pH of the reaction solution.

STUDIES ON RADICAL POLYMERIZATION OF METHYL METHACRYLATE INITIATED WITH ORGANIC PEROXIDE-AMINE SYSTEMS

Institute of Scientific and Technical Information of China (English)

QIU Kunyuan; SHUI Li; FENG Xinde

1984-01-01

Radical polymerization of methyl methacrylate (MMA) initiated with various diacyl peroxideamine systems was studied. Benzoyl peroxide (BPO) and lauroyl peroxide (LPO) were used as diacyl peroxide component, N,N-dimethyl aniline (DMA) and its para substituted derivatives, i.e., N,N-dimethyl-p-toluidine (DMT), p-hydroxymethyl-N,N-dimethyl aniline (HDMA), p-nitro-N,N-dimethyl aniline (NDMA) and p-dimethylamino benzaldehyde (DMAB) were used as amine components. It was found that the peroxide-DMT systems give higher rates of bulk polymerization Rp of MMA than the organic hydroperoxide-DMT systems with the following descending order BPO-DMT＞LPO-DMT＞CHP (cumene hydroperoxide)-DMT＞TBH (tert-butyl hydroperoxide)-DMT.The aromatic tertiary amines possess obvious structural effect on the Rp values in the diacyl peroxideamine system. The overall activation energy of MMA polymerization was determined and the kinetics of polymerization of MMA initiated with BPO-DMT system was investigated.

Limonene hydroperoxide analogues show specific patch test reactions.

Science.gov (United States)

Christensson, Johanna Bråred; Hellsén, Staffan; Börje, Anna; Karlberg, Ann-Therese

2014-05-01

The fragrance terpene R-limonene is a very weak sensitizer, but forms allergenic oxidation products upon contact with air. The primary oxidation products of oxidized limonene, the hydroperoxides, have an important impact on the sensitizing potency of the oxidation mixture. One analogue, limonene-1-hydroperoxide, was experimentally shown to be a significantly more potent sensitizer than limonene-2-hydroperoxide in the local lymph node assay with non-pooled lymph nodes. To investigate the pattern of reactivity among consecutive dermatitis patients to two structurally closely related limonene hydroperoxides, limonene-1-hydroperoxide and limonene-2-hydroperoxide. Limonene-1-hydroperoxide, limonene-2-hydroperoxide, at 0.5% in petrolatum, and oxidized limonene 3.0% pet. were tested in 763 consecutive dermatitis patients. Of the tested materials, limonene-1-hydroperoxide gave most reactions, with 2.4% of the patients showing positive patch test reactions. Limonene-2-hydroperoxide and oxidized R-limonene gave 1.7% and 1.2% positive patch test reactions, respectively. Concomitant positive patch test reactions to other fragrance markers in the baseline series were frequently noted. The results are in accordance with the experimental studies, as limonene-1-hydroperoxide gave more positive patch test reactions in the tested patients than limonene-2-hydroperoxide. Furthermore, the results support the specificity of the allergenic activity of the limonene hydroperoxide analogues and the importance of oxidized limonene as a cause of contact allergy. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

A new automated colorimetric method for measuring total oxidant status.

Science.gov (United States)

Erel, Ozcan

2005-12-01

To develop a new, colorimetric and automated method for measuring total oxidation status (TOS). The assay is based on the oxidation of ferrous ion to ferric ion in the presence of various oxidant species in acidic medium and the measurement of the ferric ion by xylenol orange. The oxidation reaction of the assay was enhanced and precipitation of proteins was prevented. In addition, autoxidation of ferrous ion present in the reagent was prevented during storage. The method was applied to an automated analyzer, which was calibrated with hydrogen peroxide and the analytical performance characteristics of the assay were determined. There were important correlations with hydrogen peroxide, tert-butyl hydroperoxide and cumene hydroperoxide solutions (r=0.99, Ptotal antioxidant capacity (TAC) (r=-0.66 Ptotal oxidant status.

Preparation of Langmuir–Blodgett thin films of calix[6]arenes and p-tert butyl group effect on their gas sensing properties

Energy Technology Data Exchange (ETDEWEB)

Ozmen, Mustafa, E-mail: musozmen@gmail.com [Department of Chemistry, University of Selcuk, 42075 Konya (Turkey); Ozbek, Zikriye, E-mail: zikriye@comu.edu.tr [Department of Bioengineering, University of Canakkale Onsekiz Mart, 17100 Canakkale (Turkey); Bayrakci, Mevlut [Department of Bioengineering, University of Karamanoglu Mehmetbey, 70200 Karaman (Turkey); Ertul, Seref; Ersoz, Mustafa [Department of Chemistry, University of Selcuk, 42075 Konya (Turkey); Capan, Rifat [Department of Physics, University of Balikesir, 10145 Balikesir (Turkey)

2015-12-30

Graphical abstract: - Highlights: • In this work, we prepared Langmuir–Blodgett films of calix[6]arene derivatives. • Then LB films of calixarene compounds were characterized. • Organic vapor sensing properties of prepared LB films were investigated. - Abstract: Organic vapor sensing properties of Langmuir–Blodgett (LB) thin films of p-tert-butyl calix[6]arene and calix[6]arene, and their certain characterization are reported in this work. LB films of these calixarenes have been characterized by contact angle measurement, quartz crystal microbalance (QCM), scanning electron microscopy (SEM) and atomic force microscopy (AFM). QCM system was used for the measurement of sensor response against chloroform, benzene, toluene and ethanol vapors. Forming of stable monolayers was observed at the water surface using surface pressure–area isotherm graph. The results indicate that good quality, uniform LB films can be prepared with a transfer ratio of over 0.95. Due to the adsorption of vapors into the LB film structures; they yield a response to all vapors as of large, fast, and reproducible.

FT-IR, FT-Raman spectra, density functional computations of the vibrational spectra and molecular conformational analysis of 2,5-di-tert-butyl-hydroquinone

Science.gov (United States)

Subramanian, N.; Sundaraganesan, N.; Dereli, Ö.; Türkkan, E.

2011-12-01

The purpose of finding conformer among six different possible conformers of 2,5-di-tert-butyl-hydroquinone (DTBHQ), its equilibrium geometry and harmonic wavenumbers were calculated by the B3LYP/6-31G(d,p) method. The infrared and Raman spectra of DTBHQ were recorded in the region 400-4000 cm -1 and 50-3500 cm -1, respectively. In addition, the IR spectra in CCl 4 at various concentrations of DTBHQ are also recorded. The computed vibrational wavenumbers were compared with the IR and Raman experimental data. Computational calculations at B3LYP level with two different basis sets 6-31G(d,p) and 6-311++G(d,p) are also employed in the study of the possible conformer of DTBHQ. The complete assignments were performed on the basis of the potential energy distribution (PED) of the vibrational modes, calculated using VEDA 4 program. The general agreement between the observed and calculated frequencies was established.

Polypyrrole-Grafted Coconut Shell Biological Carbon as a Potential Adsorbent for Methyl Tert-Butyl Ether Removal: Characterization and Adsorption Capability

Directory of Open Access Journals (Sweden)

Shanshan Li

2017-01-01

Full Text Available Methyl tert-butyl ether (MTBE has been used as a common gasoline additive worldwide since the late twentieth century, and it has become the most frequently detected groundwater pollutant in many countries. This study aimed to synthesize a novel microbial carrier to improve its adsorptive capacity for MTBE and biofilm formation, compared to the traditional granular activated carbon (GAC. A polypyrrole (PPy-modified GAC composite (PPy/GAC was synthesized, and characterized by Fourier transform infrared spectroscopy (FT-IR and Brunauer-Emmett-Teller (BET surface area analysis. The adsorption behaviors of MTBE were well described by the pseudo-second-order and Langmuir isotherm models. Furthermore, three biofilm reactors were established with PPy/GAC, PPy, and GAC as the carriers, respectively, and the degradation of MTBE under continuous flow was investigated. Compared to the biofilm reactors with PPy or GAC (which both broke after a period of operation, the PPy/GAC biofilm column produced stable effluents under variable treatment conditions with a long-term effluent MTBE concentration <20 μg/L. Pseudomonas aeruginosa and Acinetobacter pittii may be the predominant bacteria responsible for MTBE degradation in these biofilm reactors.

Equilibrium surface tension and the interaction energy of DMSO with tert-butyl alcohol or iso-amyl alcohol at various temperatures

International Nuclear Information System (INIS)

Bagheri, Ahmad; Moradian, Zohreh

2014-01-01

Highlights: • Surface tension of non-ideal binary systems of alcohol/DMSO determined. • The surface tension data of binary mixtures were correlated with five equations. • The interaction energy values were calculated by using LWW model. • The U 12 value shows different behavior for two systems with increasing temperature. - Abstract: Surface tension of binary mixtures of tert-butyl alcohol (TBA) and iso-amyl alcohol (IAA) with DMSO (dimethyl sulfoxide) were measured over the entire concentration range at pressure of 82.5 kPa at temperatures between (298.15 and 328.15) K. Correlating the surface tension and surface tension deviation of the above mentioned binary systems was performed with empirical and thermodynamic based models. The average relative error obtained from the comparison of experimental and calculated surface tension values for the two binary systems with five models at various temperatures is less than 2%. The effect of temperature on the interaction energy values in binary mixtures has been used to obtain information about solute structural effects on DMSO. Also, the experimental data were used to evaluate the nature and type of intermolecular interactions in binary mixtures

TOXICITY OF METHYL-TERT BYTYL ETHER (MTBE) TO PLANTS (AVENA SATIVA, ZEA MAYS, TRITICUM AESTIVUM, AND LACTUCA SATIVA)

Science.gov (United States)

Effects of Methyl tert-butyl ether (MTBE) on the germination of seeds and growth of the plant were studied in some laboratory experiments. Test plants were wild oat (Avena sative), sweet corn (Zea mays), wheat (Triticum aestivum), and lettuce (Lactuca sativa). Seed germination,...

Absorption, Distribution, and Clearanace o f2,6-Di-tert-Butyl-4-nitrophenol (DBNP)

National Research Council Canada - National Science Library

Still, K

2002-01-01

.... DBNP is produced when oil mist from synthetic steam turbine lubricants containing the antioxidant 2,6-Di-tert-butylphenol is nitrated during passage through the submarine air filtration system...

Poly (ethylene oxide)-block-poly (n-butyl acrylate)-blockpoly (acrylic acid) triblock terpolymers with highly asymmetric hydrophilic blocks: synthesis and aqueous solution properties

OpenAIRE

Petrov, P. (Petar); Yoncheva, K. (Krassimira); Mokreva, P. (Pavlina); Konstantinov, S. (Spiro); Irache, J.M. (Juan Manuel); Müller, A.H.E. (Axel H.E.)

2013-01-01

The synthesis and aggregation behaviour in aqueous media of novel amphiphilic poly(ethylene oxide)- block-poly(n-butyl acrylate)-block-poly(acrylic acid) (PEO–PnBA–PAA) triblock terpolymers were studied. Terpolymers composed of two highly asymmetric hydrophilic PEO (113 monomer units) and PAA (10–17 units) blocks, and a longer soft hydrophobic PnBA block (163 or 223 units) were synthesized by atom transfer radical polymerisation (ATRP) of n-butyl acrylate and tert-butyl acrylate ...

Synthesis and Structure Determination of Di-tert-butyltin (IV) Dithiocarbamate)

International Nuclear Information System (INIS)

Amirah Faizah Abdul Muthalib; Ibrahim Baba; Yang Farina Abdul Aziz; Mohd Wahid Samsudin

2013-01-01

New diorganotin (IV) dithiocarbamate complexes have been synthesized from di-tert-butyltin (IV) dichloride, N-dialkylamine and carbon disulphide. Elemental and gravimetric analysis confirmed the general formula of these complexes as (t- C 4 H 9 ) 2 Sn[S 2 CNR 1 R 2 ] 2 (R 1 = CH 3 , C 2 H 5 , C 7 H 7 dan R 2 = C 2 H 5 , C 6 H 11 , iC 3 H 7 , CH 3 , C 2 H 5 , C 4 H 9 , C 7 H 7 ). The structures of these complexes have been elucidated on the basis of infrared, ultraviolet, 1 H, 13 C and 119 Sn NMR spectroscopy and X-ray crystallography. The infrared spectra of these complexes showed three main peaks for v(C-N), v(C-S) and v(Sn-S) bands that appeared in the region of 1447-1496, 947-988 and 352-370 cm -1 , respectively. The 13 C NMR spectrum showed the chemical shift for ?(N 13 CS 2 ) in the range of 199.1-201.8 ppm. X-ray single crystal structure (C 4 H 9 ) 2 Sn[S 2 CN(CH 3 )(iC 3 H 7 )] 2 demonstrated a six-coordination geometry around the tin atom adopting a monoclinic system with a space group of P2/n with a = 11.2934(11) Angstrom, b = 7.0175(7) Angstrom, c = 15.6894(15) Angstrom; β = 95.016(1) degree. The (N-benzyl-N-ethyl dithiocarbamato)chloride di-tert-butyltin(IV) and (N,N-dibenzyl dithiocarbamato)chloride-di-(tert-butyl)tin(IV) formed a different geometry with one dithiocarbamate ligand and one chlorine atom attached to the tin centre to form a five-coordinate structure. Crystal of (N-benzyl-N-ethyl dithiocarbamato)chloride di-tert-butyltin(IV) adopts a triclinic system with space group of P1 and cell parameter of a = 8.6140 (2) Angstrom, b = 10.9604 (3) Angstrom, c = 11.4765 (3) Angstrom; α = 91.858 (2) degree, β = 96.193 (2) degree, γ = 96.011 (2) degree, while (N,N-dibenzyl dithiocarbamato)chloride-di-(tert-butyl)tin(IV) adopts a monoclinic system with space group of P2 i with cell parameter a = 9.0600 (2) Angstrom, b = 10.9238 (2) Angstrom, c = 12.7845 (3) Angstrom; β= 102.759 (2) degree. (author)

Cobalt(II Complexes with N,N,N-Scorpionates and Bidentate Ligands: Comparison of Hydrotris(3,5-dimethylpyrazol-1-ylborate Tp* vs. Phenyltris(4,4-dimethyloxazolin-2-ylborate ToM to Control the Structural Properties and Reactivities of Cobalt Centers

Directory of Open Access Journals (Sweden)

Toshiki Nishiura

2018-06-01

Full Text Available Scorpionate ligands Tp* (hydrotris(3,5-dimethylpyrazol-1-ylborate and ToM (tris(4,4-dimethyloxazolin-2-ylphenylborate complexes of cobalt(II with bidentate ligands were synthesized. Both Tp* and ToM coordinate to cobalt(II in a tridentate fashion when the bidentate ligand is the less hindered acetylacetonate. In crystal structures, the geometry of cobalt(II supported by the N3O2 donor set in the Tp* complex is a square-pyramid, whereas that in the ToM complex is close to a trigonal-bipyramid. Both Tp*- and ToM-acac complexes exhibit solvatochromic behavior, although the changing structural equilibria of these complexes in MeCN are quite different. In the bis(1-methylimidazol-2-ylmethylphenylborate (LPh complexes, Tp* retains the tridentate (к3 mode, whereas ToM functions as the bidentate (к2 ligand, giving the tetrahedral cobalt(II complex. The bowl-shaped cavity derived from the six methyl groups on ToM lead to susceptibility to the bulkiness of the opposite bidentate ligand. The entitled scorpionate compounds mediate hydrocarbon oxidation with organic peroxides. Allylic oxidation of cyclohexene occurs mainly on the reaction with tert-butyl hydroperoxide (TBHP, although the catalytic efficiency of the scorpionate ligand complexes is lower than that of Co(OAc2 and Co(acac2. On cyclohexane oxidation with meta-chloroperbenzoic acid (mCPBA, both ToM and Tp* complexes function as catalysts for hydroxylation. The higher electron-donating ToM complexes show faster initial reaction rates compared to the corresponding Tp* complexes.

Two related lithium calixarene complexes, [p-tert-butylcalix[4]arene(OMe)(OH)2(OLi)](2).4MeCN and {p-tert-butylcalix[4]arene(OH)2(OLi)[OLi(NCMe)2]}(2).8MeCN, determined using synchrotron radiation.

Science.gov (United States)

Lee, Darren S; Elsegood, Mark R J; Redshaw, Carl; Zhan, Shuzhong

2009-08-01

The crystal structures of acetonitrile solvates of two related lithium calixarene complexes have been determined by low-temperature single-crystal X-ray diffraction using synchrotron radiation. Bis(mu-5,11,17,23-tetra-tert-butyl-26,28-dihydroxy-25-methoxy-27-oxidocalix[4]arene)dilithium(I) acetonitrile tetrasolvate, [Li2(C45H57O4)2].4C2H3N or [p-tert-butylcalix[4]arene(OMe)(OH)2(OLi)](2).4MeCN, (I), crystallizes with the complex across a centre of symmetry and with four molecules of unbound acetonitrile of crystallization per complex. Tetraacetonitrilebis(mu-5,11,17,23-tetra-tert-butyl-26,28-dihydroxy-25,27-dioxidocalix[4]arene)tetralithium(I) acetonitrile octasolvate, [Li4(C44H54O4)2(C2H3N)4].8C2H3N or {p-tert-butylcalix[4]arene(OH)2(OLi)[OLi(NCMe)2]}(2).8MeCN, (II), also crystallizes with the complex lying across a centre of symmetry and contains eight molecules of unbound acetonitrile per complex plus four more directly bound to two of the lithium ions, two on each ion. The cores of both complexes are partially supported by O-H...O hydrogen bonds. The methoxy methyl groups in (I) prevent the binding of any more than two Li+ ions, while the corresponding two O-atom sites in (II) bind an extra Li(+) ion each, making four in total. The calixarene cone adopts an undistorted cone conformation in (I), but an elliptical one in (II).

Asymmetric oxidation of 1,3-dithianes to 1,3-dithiane 1-oxides

OpenAIRE

Yoshihiko, Watanabe; Yojiro, Ono; Yoshio, Ueno; Takeshi, Toru

1998-01-01

Oxidation of 2-(1-hydroxy-1-methylethyl)-1,3-dithiane with the Sharpless reagent has been examined under various reaction conditions. Oxidation of 2-(1-hydroxy-1-methylethyl)-1,3-dithiane with Ti(OPri)4-diethyl L-(+)-tartrate-tert-butyl hydroperoxide (1:2:1.5) in CH2Cl2 in the presence of 4 A molecular sieves gives (1S,2S)-2-(1-hydroxy-1-methylethyl)-1,3-dithiane 1-oxide with high trans selectivity and with moderate enantioselectivity. The enantioselectivity depends upon the substituent at t...

Magnetocaloric properties of manganese(III) porphyrins bearing 2,6-di-tert-butylphenol groups

Energy Technology Data Exchange (ETDEWEB)

Korolev, V.V., E-mail: vvk@isc-ras.ru [G. A. Krestov Institute of Solution Chemistry of the Russian Academy of Sciences, Akademicheskaya str., 1, Ivanovo 153045 (Russian Federation); Lomova, T.N.; Maslennikova, A.N.; Korolev, D.V. [G. A. Krestov Institute of Solution Chemistry of the Russian Academy of Sciences, Akademicheskaya str., 1, Ivanovo 153045 (Russian Federation); Shpakovsky, D.B.; Zhang, Jianwei; Milaeva, E.R. [Lomonosov Moscow State University, Department of Medicinal Chemistry and Fine Organic Synthesis, Moscow 119991 (Russian Federation)

2016-03-01

Magnetocaloric effect (MCE) and heat capacity during the magnetization of (5,10,15,20-tetrakis(3,5-di-tert-butyl-4-hydroxyphenyl)porphynato) manganese (III) chloride (1), (5-(4-hydroxyphenyl)-10,15,20-tris(3,5-di-tert-butyl-4-hydroxyphenyl) porphynato) manganese (III) chloride (2), and (5-(4-palmitoyloxyphenyl)-10,15,20-tris(3,5-di-tert-butyl-4-hydroxyphenyl) porphynato) manganese (III) chloride (3) in their aqueous suspensions were determined by the microcalorimetric method over the temperature range of 278–320 K and in magnetic fields from 0 to 1 T. MCE was positive for all complexes studied, i.e. the magnetic field impression under adiabatic conditions led to an increase in temperature of the complexes suspensions. MCE increased with an increase in the magnetic field induction at all temperatures studied. Dependences of MCE on temperature had weak maxima at 298 K at all magnetic induction values. The disturbance of the intermolecular hydrogen-bonding of hydroxyl groups is one of probable reasons for such dependences type. MCE values increased under the palmitoyl substituent incorporation into one of the phenol groups at all temperatures. The heat capacity of the studied complexes rose slightly with temperature growth. Dependences of the heat capacity on temperature showed that the magnetic component of the heat capacity did not appear due to the presence of the manganese atom acting as a paramagnetic center in complexes 1, 2, and 3. The relation between the complexes structure and their magnetothermal properties was analyzed. It was justified that the changes of magnetothermal properties were caused by electronic substitution effects and, to an even greater degree, by the conditions of intermolecular hydrogen bonds formation in the paramagnetic materials. - Highlights: • The magnetocaloric effect and heat capacity of 3 manganese porphyrin were determined. • Temperature dependences of magnetocaloric effect has been studied. • The relation between the

Whole-genome analysis of the methyl tert-butyl ether-degrading beta-proteobacterium Methylibium petroleiphilum PM1.

Science.gov (United States)

Kane, Staci R; Chakicherla, Anu Y; Chain, Patrick S G; Schmidt, Radomir; Shin, Maria W; Legler, Tina C; Scow, Kate M; Larimer, Frank W; Lucas, Susan M; Richardson, Paul M; Hristova, Krassimira R

2007-03-01

Methylibium petroleiphilum PM1 is a methylotroph distinguished by its ability to completely metabolize the fuel oxygenate methyl tert-butyl ether (MTBE). Strain PM1 also degrades aromatic (benzene, toluene, and xylene) and straight-chain (C(5) to C(12)) hydrocarbons present in petroleum products. Whole-genome analysis of PM1 revealed an approximately 4-Mb circular chromosome and an approximately 600-kb megaplasmid, containing 3,831 and 646 genes, respectively. Aromatic hydrocarbon and alkane degradation, metal resistance, and methylotrophy are encoded on the chromosome. The megaplasmid contains an unusual t-RNA island, numerous insertion sequences, and large repeated elements, including a 40-kb region also present on the chromosome and a 29-kb tandem repeat encoding phosphonate transport and cobalamin biosynthesis. The megaplasmid also codes for alkane degradation and was shown to play an essential role in MTBE degradation through plasmid-curing experiments. Discrepancies between the insertion sequence element distribution patterns, the distributions of best BLASTP hits among major phylogenetic groups, and the G+C contents of the chromosome (69.2%) and plasmid (66%), together with comparative genome hybridization experiments, suggest that the plasmid was recently acquired and apparently carries the genetic information responsible for PM1's ability to degrade MTBE. Comparative genomic hybridization analysis with two PM1-like MTBE-degrading environmental isolates (approximately 99% identical 16S rRNA gene sequences) showed that the plasmid was highly conserved (ca. 99% identical), whereas the chromosomes were too diverse to conduct resequencing analysis. PM1's genome sequence provides a foundation for investigating MTBE biodegradation and exploring the genetic regulation of multiple biodegradation pathways in M. petroleiphilum and other MTBE-degrading beta-proteobacteria.

Comparison of stabilization by Vitamin E and 2,6-di-tert-butylphenols during polyethylene radio-thermal-oxidation

Science.gov (United States)

Richaud, Emmanuel

2014-10-01

This paper reports a compilation of data for PE+Vitamin E and 2,6-di-tert-butylphenols oxidation in radio-thermal ageing. Data unambiguously show that Vitamin E reacts with Prad and POOrad whereas 2,6-di-tert-butyl phenols only react with POOrad. Kinetic parameters of the stabilization reactions for both kinds of antioxidants were tentatively extracted from phenol depletion curves, and discussed regarding the structure of the stabilizer. They were also used for completing an existing kinetic model used for predicting the stabilization by antioxidants. This one permits to compare the efficiency of stabilizer with dose rate or sample thickness.

Comparison of stabilization by Vitamin E and 2,6-di-tert-butylphenols during polyethylene radio-thermal-oxidation

International Nuclear Information System (INIS)

Richaud, Emmanuel

2014-01-01

This paper reports a compilation of data for PE+Vitamin E and 2,6-di-tert-butylphenols oxidation in radio-thermal ageing. Data unambiguously show that Vitamin E reacts with P · and POO · whereas 2,6-di-tert-butyl phenols only react with POO · . Kinetic parameters of the stabilization reactions for both kinds of antioxidants were tentatively extracted from phenol depletion curves, and discussed regarding the structure of the stabilizer. They were also used for completing an existing kinetic model used for predicting the stabilization by antioxidants. This one permits to compare the efficiency of stabilizer with dose rate or sample thickness. - Highlights: • Radio-thermal oxidation of PE+phenolic antioxidants. • Comparison of Vitamin E and 2,6-di-tert-butylphenols. • Kinetic modeling for predicting practical cases

Biofiltration and inhibitory interactions of gaseous benzene, toluene, xylene, and methyl tert-butyl ether.

Science.gov (United States)

Shim, Eun-Hwa; Kim, Jaisoo; Cho, Kyung-Suk; Ryu, Hee Wook

2006-05-01

This study evaluated the individual and combined removal capacities of benzene, toluene, and xylene (B, T, and X) in the presence and absence of methyl tert-butyl ether (MTBE) in a polyurethane biofilter inoculated with a BTX-degrading microbial consortium, and further examined their interactive effects in various mixtures. In addition, Polymerase chain reaction-denaturing gradient gel electrophoresis and phylogenetic analysis of 16S rRNA gene sequences were used to compare the microbial community structures found in biofilters exposed to the various gases and gas mixtures. The maximum individual elimination capacities (MECs) of B, T, and X were 200, 238, and 400 g m(-3) h(-1), respectively. There was no significant elimination of MTBE alone. Addition of MTBE decreased the MECs of B,T, and X to 75, 100, and 300 g m(-3) h(-1), respectively, indicating that benzene was most strongly inhibited by MTBE. When the three gases were mixed (B + T + X), the removal capacities of individual B, T, and X were 50, 90, and 200 g m(-3) h(-1), respectively. These capacities decreased to 40, 50, and 100 g m(-3) h(-1) when MTBE was added to the mix. The MEC of the three-gas mixture (B + T + X) was 340 g m(-3) h(-1), and that of the four-gas mixture was 200 g m(-3) h(-1). Although MTBE alone was not degraded by the biofilter, it could be co-metabolically degraded in the presence of toluene, benzene, or xylene with the MECs of 34, 23, and 14 g m(-3) h(-1), respectively. The microbial community structure analysis revealed that two large groups could be distinguished based on the presence or absence of MTBE, and many of the dominant bacteria in the consortia were closely related to bacteria isolated from aromatic hydrocarbon-contaminated sites and/ or oil wastewaters. These findings provide important new insights into biofiltration and may be used to improve the rational design of biofilters for remediation of petroleum gas-contaminated airstreams according to composition types of mixed

Electrorheological Properties of Suspensions Prepared from Poly(Li-tert-butyl methacrylate) Ionomer

OpenAIRE

YAVUZ, Mustafa

2014-01-01

The synthesis, characterisation and partial hydrolysis of poly(tert-butylmethacrylate), (PTBMA), and the electrorheological (ER) properties of its suspensions were investigated. The polymer was synthesised by radical polymerisation and partially hydrolysed by para-toluenesulphonic acid monohydrate (PTSA.H2O), and then converted to a lithium salt (PTBMA-Li) by washing with a LiOH(aq) solution. From particle size measurements, the average particle size of PTBMA-Li was determined to be ...

Matrix isolation spectroscopy and molecular dynamics simulations for 2,7,12,17-tetra-tert-butylporphycene in argon and xenon

International Nuclear Information System (INIS)

Kyrychenko, Alexander; Gawinkowski, Sylwester; Urbanska, Natalia; Pietraszkiewicz, Marek; Waluk, Jacek

2007-01-01

Electronic absorption spectra of 2,7,12,17-tetra-tert-butylporphycene (TTPC) have been recorded in low-temperature argon and xenon matrices for various deposition conditions. In the region of the S 0 -S 1 electronic transition, the spectra of TTPC in argon reveal a rich site structure, characterized by a series of more than 30 absorption peaks. Studies of the temperature dependence of the electronic spectra in solid argon demonstrated remarkable spectral changes, resulting in the broadening of all bands with increasing temperature. These temperature-induced spectral changes are, to a large degree, reversible, so lowering of temperature is accompanied by the recovery of the original fine-line spectrum. The absorption spectra in xenon reveal broad bands, on which a rich pattern of lines becomes superimposed at low temperatures. Trapping site distribution and the structure of the microenvironment around the TTPC chromophore, embedded in argon and xenon hosts, have been analyzed using molecular dynamics (MD) simulations. The MD results show that the trapping of TTPC in rare-gas solids is influenced by favorable embedding of the bulky tert-butyl groups inside the matrix cage. The crucial role of the tert-butyl groups for the thermodynamics and kinetics of matrix deposition is demonstrated by comparing the results with those obtained for the parent, unsubstituted porphycene

Stable carbon and hydrogen isotope analysis of methyl tert-butyl ether and tert-amyl methyl ether by purge and trap-gas chromatography-isotope ratio mass spectrometry: method evaluation and application.

Science.gov (United States)

Kujawinski, Dorothea M; Stephan, Manuel; Jochmann, Maik A; Krajenke, Karen; Haas, Joe; Schmidt, Torsten C

2010-01-01

In order to monitor the behaviour of contaminants in the aqueous environment effective enrichment techniques often have to be employed due to their low concentrations. In this work a robust and sensitive purge and trap-gas chromatography-isotope ratio mass spectrometry method for carbon and hydrogen isotope analysis of fuel oxygenates in water is presented. The method evaluation included the determination of method detection limits, accuracy and reproducibility of deltaD and delta(13)C values. Lowest concentrations at which reliable delta(13)C values could be determined were 5 microg L(-1) and 28 microg L(-1) for TAME and MTBE, respectively. Stable deltaD values for MTBE and TAME could be achieved for concentrations as low as 25 and 50 microg L(-1). Good long-term reproducibility of delta(13)C and deltaD values was obtained for all target compounds. But deltaD values varying more than 5 per thousand were observed using different thermal conversion tubes. Thus, a correction of deltaD values in the analysis of groundwater samples was necessary to guarantee comparability of the results. The applicability of this method was shown by the analysis of groundwater samples from a gasoline contaminated site. By two dimensional isotope analysis two locations within this site were identified at which anaerobic and aerobic degradation of methyl tert-butyl ether occurred.

Thermally Activated Paramagnets from Diamagnetic Polymers of Biphenyl-3,5-diyl Bis(tert-butyl Nitroxides Carrying Methyl and Fluoro Groups at the 2’- and 5’-Positions

Directory of Open Access Journals (Sweden)

Toru Yoshitake

2016-03-01

Full Text Available Three new biradicals—2’,5’-dimethyl-, 2’-fluoro-5’-methyl-, and 5’-fluoro-2’-methyl- biphenyl-3,5-diyl bis(tert-butyl nitroxides—were synthesized. The magnetic susceptibility measurements revealed their diamagnetism below and around room temperature. The nitroxide groups are located close to each other in an intermolecular fashion to form a weakly covalent head-to-tail (NO2 ring. Biradical molecules are connected on both radical sites, constructing a diamagnetic chain. The dimethyl derivative underwent a structural phase transition at 83 °C, clarified via differential scanning calorimetry and powder X-ray diffraction, and a paramagnetic solid phase with S = 1 irreversibly appeared. The other analogues exhibited a similar irreversible upsurge of the magnetic susceptibility on heating, but the transition was characterized as the melting.

Highly Diastereoselective Synthesis of 2-(1-N-Boc-aminoalkyl)thiazole-5-carboxylates by Reduction of tert-Butylsulfinyl Ketimines.

Science.gov (United States)

Magata, Takuji; Hirokawa, Yoshimi; Furokawa, Aya; Takeuchi, Kazuhisa; Ohtomo, Yoshiaki; Kino, Toshitaka; Kominami, Jun; Nakai, Yuto; Kitamura, Maria; Maezaki, Naoyoshi

2018-01-01

Positional isomers of naturally occurring peptide subunits were synthesized via highly diastereoselective reduction of tert-butylsulfinyl ketimines as a key reaction. While NaBH 4 reduction of ketimines derived from 2-thiazolyl ketones afforded the (R S ,R)-isomer with moderate diastereoselectivity, L-Selectride ® reduction afforded the (R S ,S)-isomer as the sole product. In contrast, ketimines derived from tert-butyl 2-thiazolyl ketone afforded the (R S ,R)-isomer with low diastereoselectivity by both NaBH 4 and L-Selectride ® reduction. Stereochemistry of the reaction was discussed based on calculation of the conformational energies for ketimines.

3,6-Dibromo-9-(4-tert-butylbenzyl-9H-carbazole

Directory of Open Access Journals (Sweden)

Duan-Lin Cao

2008-08-01

Full Text Available In the title compound, C23H21Br2N, which was synthesized by the N-alkylation of 1-tert-butyl-4-(chloromethylbenzene with 3,6-dibromo-9H-carbazole, the asymmetric unit contains two unique molecules. Each carbazole ring system is essentially planar, with mean deviations of 0.0077 and 0.0089 Å for the two molecules. The carbazole planes make dihedral angles of 78.9 (2 and 81.8 (2° with the planes of the respective benzene rings.

Ablation of the mitochondrial complex IV assembly protein Surf1 leads to increased expression of the UPRMT and increased resistance to oxidative stress in primary cultures of fibroblasts

Directory of Open Access Journals (Sweden)

Gavin Pharaoh

2016-08-01

Full Text Available Mice deficient in the electron transport chain (ETC complex IV assembly protein SURF1 have reduced assembly and activity of cytochrome c oxidase that is associated with an upregulation of components of the mitochondrial unfolded protein response (UPRMT and increased mitochondrial number. We hypothesized that the upregulation of proteins associated with the UPRMT in response to reduced cytochrome c oxidase activity in Surf1−/− mice might contribute to increased stress resistance. To test this hypothesis we asked whether primary cultures of fibroblasts from Surf1−/− mice exhibit enhanced resistance to stressors compared to wild-type fibroblasts. Here we show that primary dermal fibroblasts isolated from Surf1−/− mice have increased expression of UPRMT components ClpP and Hsp60, and increased expression of Lon protease. Fibroblasts from Surf1−/− mice are significantly more resistant to cell death caused by oxidative stress induced by paraquat or tert-Butyl hydroperoxide compared to cells from wild-type mice. In contrast, Surf1−/− fibroblasts show no difference in sensitivity to hydrogen peroxide stress. The enhanced cell survival in response to paraquat or tert-Butyl hydroperoxide in Surf1−/− fibroblasts compared to wild-type fibroblasts is associated with induced expression of Lon, ClpP, and Hsp60, increased maximal respiration, and increased reserve capacity as measured using the Seahorse Extracellular Flux Analyzer. Overall these data support a protective role for the activation of the UPRMT in cell survival.

Contrasting protective effects of cannabinoids against oxidative stress and amyloid-β evoked neurotoxicity in vitro.

Science.gov (United States)

Harvey, Benjamin S; Ohlsson, Katharina S; Mååg, Jesper L V; Musgrave, Ian F; Smid, Scott D

2012-01-01

Cannabinoids have been widely reported to have neuroprotective properties in vitro and in vivo. In this study we compared the effects of CB1 and CB2 receptor-selective ligands, the endocannabinoid anandamide and the phytocannabinoid cannabidiol, against oxidative stress and the toxic hallmark Alzheimer's protein, β-amyloid (Aβ) in neuronal cell lines. PC12 or SH-SY5Y cells were selectively exposed to either hydrogen peroxide, tert-butyl hydroperoxide or Aβ, alone or in the presence of the CB1 specific agonist arachidonyl-2'-chloroethylamide (ACEA), CB2 specific agonist JWH-015, anandamide or cannabidiol. Cannabidiol improved cell viability in response to tert-butyl hydroperoxide in PC12 and SH-SY5Y cells, while hydrogen peroxide-mediated toxicity was unaffected by cannabidiol pretreatment. Aβ exposure evoked a loss of cell viability in PC12 cells. Of the cannabinoids tested, only anandamide was able to inhibit Aβ-evoked neurotoxicity. ACEA had no effect on Aβ-evoked neurotoxicity, suggesting a CB1 receptor-independent effect of anandamide. JWH-015 pretreatment was also without protective influence on PC12 cells from either pro-oxidant or Aβ exposure. None of the cannabinoids directly inhibited or disrupted preformed Aβ fibrils and aggregates. In conclusion, the endocannabinoid anandamide protects neuronal cells from Aβ exposure via a pathway unrelated to CB1 or CB2 receptor activation. The protective effect of cannabidiol against oxidative stress does not confer protection against Aβ exposure, suggesting divergent pathways for neuroprotection of these two cannabinoids. Copyright © 2011 Elsevier Inc. All rights reserved.

Disposition of 2,6-di-tert-butyl-4-nitrophenol (DBNP), a submarine atmosphere contaminant, in male Sprague-Dawley rats

International Nuclear Information System (INIS)

Still, Kenneth R.; Jung, Anne E.; Ritchie, Glenn D.; Jederberg, Warren W.; Wilfong, Erin R.; Briggs, G. Bruce; Arfsten, Darryl P.

2005-01-01

The phenol 2,6-di-tert-butyl-4-nitrophenol (DBNP) is a contaminant found onboard submarines and is formed by the nitration of an antioxidant present in turbine lubricating oil TEP 2190. DBNP has been found on submarine interior surfaces, on eating utensils and dishes, and on the skin of submariners. DBNP exposure is a potential health concern because it is an uncoupler of mitochondrial oxidative phosphorylation. Adult male rats were dosed once by oral gavage with 15 or 40 mg/kg DBNP mixed with 14 C-DBNP in kanola oil and 0.8% v/v DMSO (n=16/group). The distribution of 14 C in major tissues was measured over time for up to 240 h post-dose. Unexpectedly, 6/16 (40%) of the rats gavaged with 40 mg/kg DBNP died within 24 h of dosing. Prostration, no auditory startle response, reduced locomotor activity, and muscular rigidity persisted in survivors for up to 8 days after dosing. For animals dosed with 15 mg/kg DBNP, radioactivity levels were significantly elevated in the following tissues 24 h after dosing: fat>>>liver>kidneys>heart>lungs>brain>striated muscle>spleen. Radioactivity levels were elevated for fat, liver, kidney, heart, and lungs of animals euthanized 144 h post-dosing and in the liver of animals euthanized 240 h post-dosing. These findings suggest that DBNP may accumulate in the body as a result of continuous or repeat exposures of short interval to DBNP

Synthesis, Anti-HCV, Antioxidant and Reduction of Intracellular Reactive Oxygen Species Generation of a Chlorogenic Acid Analogue with an Amide Bond Replacing the Ester Bond.

Science.gov (United States)

Wang, Ling-Na; Wang, Wei; Hattori, Masao; Daneshtalab, Mohsen; Ma, Chao-Mei

2016-06-08

Chlorogenic acid is a well known natural product with important bioactivities. It contains an ester bond formed between the COOH of caffeic acid and the 3-OH of quinic acid. We synthesized a chlorogenic acid analogue, 3α-caffeoylquinic acid amide, using caffeic and quinic acids as starting materials. The caffeoylquinc acid amide was found to be much more stable than chlorogenic acid and showed anti-Hepatitis C virus (anti-HCV) activity with a potency similar to chlorogenic acid. The caffeoylquinc acid amide potently protected HepG2 cells against oxidative stress induced by tert-butyl hydroperoxide.

Low-temperature CVD of iron, cobalt, and nickel nitride thin films from bis[di(tert-butyl)amido]metal(II) precursors and ammonia

International Nuclear Information System (INIS)

Cloud, Andrew N.; Abelson, John R.; Davis, Luke M.; Girolami, Gregory S.

2014-01-01

Thin films of late transition metal nitrides (where the metal is iron, cobalt, or nickel) are grown by low-pressure metalorganic chemical vapor deposition from bis[di(tert-butyl)amido]metal(II) precursors and ammonia. These metal nitrides are known to have useful mechanical and magnetic properties, but there are few thin film growth techniques to produce them based on a single precursor family. The authors report the deposition of metal nitride thin films below 300 °C from three recently synthesized M[N(t-Bu) 2 ] 2 precursors, where M = Fe, Co, and Ni, with growth onset as low as room temperature. Metal-rich phases are obtained with constant nitrogen content from growth onset to 200 °C over a range of feedstock partial pressures. Carbon contamination in the films is minimal for iron and cobalt nitride, but similar to the nitrogen concentration for nickel nitride. X-ray photoelectron spectroscopy indicates that the incorporated nitrogen is present as metal nitride, even for films grown at the reaction onset temperature. Deposition rates of up to 18 nm/min are observed. The film morphologies, growth rates, and compositions are consistent with a gas-phase transamination reaction that produces precursor species with high sticking coefficients and low surface mobilities

Selective oxidation of cyclohexene through gold functionalized silica monolith microreactors

Science.gov (United States)

Alotaibi, Mohammed T.; Taylor, Martin J.; Liu, Dan; Beaumont, Simon K.; Kyriakou, Georgios

2016-04-01

Two simple, reproducible methods of preparing evenly distributed Au nanoparticle containing mesoporous silica monoliths are investigated. These Au nanoparticle containing monoliths are subsequently investigated as flow reactors for the selective oxidation of cyclohexene. In the first strategy, the silica monolith was directly impregnated with Au nanoparticles during the formation of the monolith. The second approach was to pre-functionalize the monolith with thiol groups tethered within the silica mesostructure. These can act as evenly distributed anchors for the Au nanoparticles to be incorporated by flowing a Au nanoparticle solution through the thiol functionalized monolith. Both methods led to successfully achieving even distribution of Au nanoparticles along the length of the monolith as demonstrated by ICP-OES. However, the impregnation method led to strong agglomeration of the Au nanoparticles during subsequent heating steps while the thiol anchoring procedure maintained the nanoparticles in the range of 6.8 ± 1.4 nm. Both Au nanoparticle containing monoliths as well as samples with no Au incorporated were tested for the selective oxidation of cyclohexene under constant flow at 30 °C. The Au free materials were found to be catalytically inactive with Au being the minimum necessary requirement for the reaction to proceed. The impregnated Au-containing monolith was found to be less active than the thiol functionalized Au-containing material, attributable to the low metal surface area of the Au nanoparticles. The reaction on the thiol functionalized Au-containing monolith was found to depend strongly on the type of oxidant used: tert-butyl hydroperoxide (TBHP) was more active than H2O2, likely due to the thiol induced hydrophobicity in the monolith.

Protective Effects of Maillard Reaction Products of Whey Protein Concentrate against Oxidative Stress through an Nrf2-Dependent Pathway in HepG2 Cells.

Science.gov (United States)

Pyo, Min Cheol; Yang, Sung-Yong; Chun, Su-Hyun; Oh, Nam Su; Lee, Kwang-Won

2016-09-01

Whey protein concentrate (WPC), which contains α-lactalbumin and β-lactoglobulin, is utilized widely in the food industry. The Maillard reaction is a complex reaction that produces Maillard reaction products (MRPs), which are associated with the formation of antioxidant compounds. In this study, the hepatoprotection activity of MRPs of WPC against oxidative stress through the nuclear factor-E2-related factor 2 (Nrf2)-dependent antioxidant pathway in HepG2 cells was examined. Glucose-whey protein concentrate conjugate (Glc-WPC) was obtained from Maillard reaction between WPC and glucose. The fluorescence intensity of Glc-WPC increased after 7 d compared to native WPC, and resulted in loss of 48% of the free amino groups of WPC. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) patterns of Glc-WPC showed the presence of a high-molecular-weight portion. Treatment of HepG2 cells with Glc-WPC increased cell viability in the presence of oxidative stress, inhibited the generation of intracellular reactive oxygen species by tert-butyl hydroperoxide (t-BHP), and increased the glutathione level. Nrf2 translocation and Nrf2, reduced nicotinamide adenine dinucleotide phosphate (NAD(P)H)-quinone oxidoreductase 1 (NOQ1), heme oxygenase-1 (HO-1), glutamate-L-cysteine ligase (GCL)M and GCLC mRNA levels were increased by Glc-WPC. Also, Glc-WPC increased the phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 and c-Jun N-terminal kinase (JNK). The results of this study demonstrate that Glc-WPC activates the Nrf2-dependent pathway through the phosphorylation of ERK1/2 and JNK in HepG2 cells, and induces production of antioxidant enzymes and phase II enzymes.

Enterococcus faecalis Infection and Reactive Oxygen Species Down-Regulates the miR-17-92 Cluster in Gastric Adenocarcinoma Cell Culture

Directory of Open Access Journals (Sweden)

Jesper A. B. Strickertsson

2014-08-01

Full Text Available Chronic inflammation due to bacterial overgrowth of the stomach predisposes to the development of gastric cancer and is also associated with high levels of reactive oxygen species (ROS. In recent years increasing attention has been drawn to microRNAs (miRNAs due to their role in the pathogenesis of many human diseases including gastric cancer. Here we studied the impact of infection by the gram-positive bacteria Enterococcus faecalis (E. faecalis on global miRNA expression as well as the effect of ROS on selected miRNAs. Human gastric adenocarcinoma cell line MKN74 was infected with living E. faecalis for 24 h or for 5 days or with E. faecalis lysate for 5 days. The miRNA expression was examined by microarray analysis using Affymetrix GeneChip miRNA Arrays. To test the effect of ROS, MKN74 cells were treated with 100 mM tert-Butyl hydroperoxide (TBHP. Following 5 days of E. faecalis infection we found 91 differentially expressed miRNAs in response to living bacteria and 2 miRNAs responded to E. faecalis lysate. We verified the down-regulation of the miR-17-92 and miR-106-363 clusters and of other miRNAs involved in the oxidative stress-response by qRT-PCR. We conclude that only infection by living E. faecalis bacteria caused a significant global response in miRNA expression in the MKN74 cell culture. E. faecalis infection as well as ROS stimulation down-regulated the expression of the miR-17-92 cluster. We believe that these changes could reflect a general response of gastric epithelial cells to bacterial infections.

Requirements for superoxide-dependent tyrosine hydroperoxide formation in peptides

DEFF Research Database (Denmark)

Winterbourn, Christine C; Parsons-Mair, Helena N; Gebicki, Silvia

2004-01-01

Superoxide reacts rapidly with other radicals, but these reactions have received little attention in the context of oxidative stress. For tyrosyl radicals, reaction with superoxide is 3-fold faster than dimerization, and forms the addition product tyrosine hydroperoxide. We have explored structural...... requirements for hydroperoxide formation using tyrosine analogues and di- and tri-peptides. Superoxide and phenoxyl radicals were generated using xanthine oxidase, peroxidase and the respective tyrosine derivative, or by gamma-radiation. Peroxides were measured using FeSO4/Xylenol Orange. Tyrosine and tyramine...... formed stable hydroperoxides, but N-acetyltyrosine and p-hydroxyphenylacetic acid did not, demonstrating a requirement for a free amino group. Using [14C]tyrosine, the hydroperoxide and dityrosine were formed at a molar ratio of 1.8:1. Studies with pre-formed hydroperoxides, and measurements of substrate...

Vapor-liquid equilibrium data for five binary systems of methanol, tert-butylalcohol, tert-butylmethylether and water, and quaternary reactive system producing tert-butylmethylether from methanol and tert-butylalcohol; Metanoru, tert-buchiruarukoru, tert-buchirumechirueteru oyobi mizu wo kumiawaseta 5shu no niseibunkei to metanoru to tert-buchiruarukoru ni yoru eteruka hannokei no taikiatsuka ni okeru kieki heiko deta

Energy Technology Data Exchange (ETDEWEB)

Komatsu, H.; Nakamura, M.; Yamashita, Y.; Hirai, C. [Toyohashi Univ. of Technology (Japan)

1997-11-01

At atmospheric pressure, vapor-liquid equilibrium relationships for five binary systems of methanol-tert-butylalcohol, methanol-tert-butylmethylether, tert-butylalcohol-tert-butylmethylether, water-tert-butylalcohol and water-tert-butylmethylether are observed. The Wilson parameters for the binary systems have been obtained. Comparisons between the Wilson method, The ASOG method and the UNIFAC method are made. Vapor-liquid equilibrium relationships of the quaternary reactive system producing tert-butylmethylether by use of methanol and tert-butylalcohol are also observed, and it is confirmed that the Wilson parameters resulting from the data of binary systems can be used to estimate the vapor-liquid equilibrium data for the quaternary reactive system of methanol-tert-butylalcohol-tert-butylmethylether-water. 6 refs., 7 figs., 5 tabs.

Solid binary mixtures of neopentanol with tert-Butyl chloride and carbon tetrachloride studied by thermal, X-ray and dielectric techniques

Energy Technology Data Exchange (ETDEWEB)

Chandra, Girish; Murthy, S.S.N., E-mail: ssnm0700@gmail.com

2016-05-10

Highlights: • DSC, dielectric and X-ray measurements have been done on TBC-NPOH and CTC-NPOH. • The results show the formation of solid solution for concentrations 0.7 ≤ x{sub m} ≤ 0.9. • A primary α-process and two sub-T{sub g} processes are found for TBC-NPOH. • For CTC-NPOH only one sub-T{sub g} process is found. • All the three sub-T{sub g} processes are Johari–Goldstein type. - Abstract: The binary mixtures of Neopentanol (NPOH) with tert-Butyl chloride (TBC) and Carbon tetrachloride (CTC), have been studied using Differential Scanning Calorimetry, Dielectric spectroscopy and X-ray diffraction techniques. The results indicate the formation of the solid solutions. The crystalline solid thus formed is found to be orientationally disordered and supercools easily to form glassy crystal for mole fraction of NPOH in the range of 0.7–0.9. The T{sub g} values are in the range of 140–147 K. In the dielectric study, a primary α-process and two sub-T{sub g} processes are found for TBC-NPOH, whereas for CTC-NPOH only one sub-T{sub g} process is found. The dielectric spectra of α- process follows the Havriliak–Negami equation. The sub-T{sub g} processes follow the Cole–Cole equation, and are found to be of Johari–Goldstein type, indicating intermolecular nature.

Whole-Genome Analysis of the Methyl tert-Butyl Ether-Degrading Beta-Proteobacterium Methylibium petroleiphilum PM1▿ †

Science.gov (United States)

Kane, Staci R.; Chakicherla, Anu Y.; Chain, Patrick S. G.; Schmidt, Radomir; Shin, Maria W.; Legler, Tina C.; Scow, Kate M.; Larimer, Frank W.; Lucas, Susan M.; Richardson, Paul M.; Hristova, Krassimira R.

2007-01-01

Methylibium petroleiphilum PM1 is a methylotroph distinguished by its ability to completely metabolize the fuel oxygenate methyl tert-butyl ether (MTBE). Strain PM1 also degrades aromatic (benzene, toluene, and xylene) and straight-chain (C5 to C12) hydrocarbons present in petroleum products. Whole-genome analysis of PM1 revealed an ∼4-Mb circular chromosome and an ∼600-kb megaplasmid, containing 3,831 and 646 genes, respectively. Aromatic hydrocarbon and alkane degradation, metal resistance, and methylotrophy are encoded on the chromosome. The megaplasmid contains an unusual t-RNA island, numerous insertion sequences, and large repeated elements, including a 40-kb region also present on the chromosome and a 29-kb tandem repeat encoding phosphonate transport and cobalamin biosynthesis. The megaplasmid also codes for alkane degradation and was shown to play an essential role in MTBE degradation through plasmid-curing experiments. Discrepancies between the insertion sequence element distribution patterns, the distributions of best BLASTP hits among major phylogenetic groups, and the G+C contents of the chromosome (69.2%) and plasmid (66%), together with comparative genome hybridization experiments, suggest that the plasmid was recently acquired and apparently carries the genetic information responsible for PM1's ability to degrade MTBE. Comparative genomic hybridization analysis with two PM1-like MTBE-degrading environmental isolates (∼99% identical 16S rRNA gene sequences) showed that the plasmid was highly conserved (ca. 99% identical), whereas the chromosomes were too diverse to conduct resequencing analysis. PM1's genome sequence provides a foundation for investigating MTBE biodegradation and exploring the genetic regulation of multiple biodegradation pathways in M. petroleiphilum and other MTBE-degrading beta-proteobacteria. PMID:17158667

Fatty acid methyl esters synthesis from non-edible vegetable oils using supercritical methanol and methyl tert-butyl ether

International Nuclear Information System (INIS)

Lamba, Neha; Modak, Jayant M.; Madras, Giridhar

2017-01-01

Highlights: • FAMEs were synthesized from non-edible oils using supercritical MeOH and MTBE. • Effect of time, temperature, pressure and molar ratio on conversions was studied. • Rate constants of reaction with methanol and MTBE differ by an order of magnitude. • Non-catalytic supercritical reactions are one order faster than acid catalyzed synthesis. - Abstract: Fatty acid methyl esters (FAMEs) are useful as biodiesel and have environmental benefits compared to conventional diesel. In this study, these esters were synthesized non-catalytically from non-edible vegetable oils: neem oil and mahua oil with two different methylating agents: methanol and methyl tert-butyl ether (MTBE). The effects of temperature, pressure, time and molar ratio on the conversion of triglycerides were studied. The temperature was varied in the range of 523–723 K with molar ratios upto 50:1 and a reaction time of upto 150 min. Conversion of neem and mahua oil to FAMEs with supercritical methanol was found to be 83% in 15 min and 99% in 10 min, respectively at 698 K. Further, a conversion of 46% of mahua oil and 59% of neem oil was obtained in 15 min at 723 K using supercritical MTBE. The rate constants evaluated using pseudo first order reaction kinetics were in the range of 4.7 × 10"−"6 to 1.0 × 10"−"3 s"−"1 for the investigated range of temperatures. The activation energies obtained were in the range of 62–113 kJ/mol for the reaction systems investigated. The supercritical synthesis was found to be superior to the catalytic synthesis of the corresponding FAMEs.

Development of an efficient process for radiation vulcanization of natural rubber latex using hydroperoxide with sensitizer

International Nuclear Information System (INIS)

Siri-upathum, C.; Sonsuk, M.

1996-01-01

An attempt was made to reduce irradiation dose for radiation vulcanization of natural rubber latex. A promising method was to partially crosslink the latex by radiation vulcanization using n-butyl acrylate (n-BA) as sensitizer and t-butyl hydroperoxide (BHPO) as a co-sensitizer followed by redox vulcanization using residual BHPO as an oxidant and either fructose or tetra ethylene penta mine as reducing agents. It was found that the irradiation dose was reduced to 4 kGy with 5 phr n-BA as sensitizer and 0.1 phr BHPO as co-sensitizer. Successive crosslinking to full vulcanization was done by redox vulcanization using either 4 phr fructose at 60 degree C for 3 hours of 0.4 phr tetra-ethylene penta mine at room temperature for 1 hour. The rubber films obtained had tensile strength of about 25 MPa, modulus 300% of 0.9 MPa and crosslink density of about 1.5 x 10 19 crosslink/cm 3 . It was noted that the rubber film from the co-vulcanization was the average value of the values obtained by radiation vulcanization and redox vulcanization

Structures of butyl ions formed by electron impact ionization of isomeric butyl halides and alkanes

International Nuclear Information System (INIS)

Shold, D.M.; Ausloos, P.

1978-01-01

Using a pulsed ion cyclotron resonance (ICR) spectrometer, it is demonstrated that at pressures of about 10 -6 Torr and at observation times ranging from 10 -3 to 0.5 s, isobutane, neopentane, 2,2-dimethylbutane, isobutyl halides, and tert-butyl halides form C 4 H 9 + ions having the tertiary structure. In n-alkanes, 2-methylbutane, 3-methylpentane, n-butyl halides, and sec-butyl halides, both sec-C 4 H 9 + and t-C 4 H 9 + ions are observed, the sec-C 4 H 9 + ions surviving without rearrangement for at least 0.1 s. However, in the case of the halides, a collision-induced isomerization of the sec-C 4 H 9 + to the t-C 4 H 9 + ions occurs. The efficiency of this process increases with the basicity of the alkyl halide. Radiolysis experiments carried out at atmospheric pressures indicate, in agreement with ICR and solution experiments, that at times as short as 10 -10 s the majority of the i-C 4 H 9 + ions from isobutyl bromide rearrange to the t-C 4 H 9 + structure. On the other hand, in the radiolysis of both n-hexane and 3-methylpentane, the abundance of t-C 4 H 9 + relative to sec-C 4 H 9 + is substantially smaller than that observed in the ICR experiments, and decreases with decreasing collision interval. It is suggested that about 90% of the i-C 4 H 9 + can rearrange to t-C 4 H 9 + by simple 1,2-hydride shift without involving secondary or protonated methylcyclopropane structures as intermediates. 4 figures, 2 tables

Oxidative and proteolysis-related parameters of skeletal muscle from hamsters with experimental pulmonary emphysema: a comparison between papain and elastase induction.

Science.gov (United States)

Brunnquell, Cláudia R; Vieira, Nichelle A; Sábio, Laís R; Sczepanski, Felipe; Cecchini, Alessandra L; Cecchini, Rubens; Guarnier, Flávia A

2015-06-01

The objective of this study was to investigate whether emphysema induced by elastase or papain triggers the same effects on skeletal muscle, related to oxidative stress and proteolysis, in hamsters. For this purpose, we evaluated pulmonary lesions, body weight, muscle loss, oxidative stress (thiobarbituric acid-reactive substances, total and oxidized glutathiones, chemiluminescence stimulated by tert-butyl hydroperoxide and carbonyl proteins), chymotrypsin-like and calpain-like proteolytic activities and muscle fibre cross-sectional area in the gastrocnemius muscles of emphysemic hamsters. Two groups of animals received different intratracheal inductions of experimental emphysema: by 40 mg/ml papain (EP) or 5.2 IU/100 g animal (EE) elastase (n = 10 animals/group). The control group received intratracheal instillation of 300 μl sterile NaCl 0.9%. Compared with the control group, the EP group had reduced muscle weight (18.34%) and the EE group had increased muscle weight (8.37%). Additionally, tert-butyl hydroperoxide-initiated chemiluminescence, carbonylated proteins and chymotrypsin-like proteolytic activity were all elevated in the EP group compared to the CS group, while total glutathione was decreased compared to the EE group. The EE group showed more fibres with increased cross-sectional areas and increased calpain-like activity. Together, these data show that elastase and papain, when used to induce experimental models of emphysema, lead to different speeds and types of adaptation. These findings provide more information on choosing a suitable experimental model for studying skeletal muscle adaptations in emphysema. © 2015 The Authors. International Journal of Experimental Pathology © 2015 International Journal of Experimental Pathology.

Recommendation to test limonene hydroperoxides 0·3% and linalool hydroperoxides 1·0% in the British baseline patch test series.

Science.gov (United States)

Wlodek, C; Penfold, C M; Bourke, J F; Chowdhury, M M U; Cooper, S M; Ghaffar, S; Green, C; Holden, C R; Johnston, G A; Mughal, A A; Reckling, C; Sabroe, R A; Stone, N M; Thompson, D; Wilkinson, S M; Buckley, D A

2017-12-01

There is a significant rate of sensitization worldwide to the oxidized fragrance terpenes limonene and linalool. Patch testing to oxidized terpenes is not routinely carried out; the ideal patch test concentration is unknown. To determine the best test concentrations for limonene and linalool hydroperoxides, added to the British baseline patch test series, to optimize detection of true allergy and to minimize irritant reactions. During 2013-2014, 4563 consecutive patients in 12 U.K. centres were tested to hydroperoxides of limonene in petrolatum (pet.) 0·3%, 0·2% and 0·1%, and hydroperoxides of linalool 1·0%, 0·5% and 0·25% pet. Irritant reactions were recorded separately from doubtful reactions. Concomitant reactions to other fragrance markers and clinical relevance were documented. Limonene hydroperoxide 0·3% gave positive reactions in 241 (5·3%) patients, irritant reactions in 93 (2·0%) and doubtful reactions in 110 (2·4%). Linalool hydroperoxide 1·0% gave positive reactions in 352 (7·7%), irritant reactions in 178 (3·9%) and doubtful reactions in 132 (2·9%). A total of 119 patients with crescendo reactions to 0·3% limonene would have been missed if only tested with 0·1% and 131 patients with crescendo reactions to 1·0% linalool would have been missed if only tested with 0·25%. In almost two-thirds of patients with positive patch tests to limonene and linalool the reaction was clinically relevant. The majority of patients did not react to any fragrance marker in the baseline series. We recommend that limonene hydroperoxides be tested at 0·3% and linalool hydroperoxides at 1·0% in the British baseline patch test series. © 2017 British Association of Dermatologists.

40 CFR 704.33 - P-tert-butylbenzoic acid (P-TBBA), p-tert-butyltoluene (P-TBT) and p-tert-butylbenzaldehyde (P-TBB).

Science.gov (United States)

2010-07-01

...-tert-butyltoluene (P-TBT) and p-tert-butylbenzaldehyde (P-TBB). 704.33 Section 704.33 Protection of... (P-TBBA), p-tert-butyltoluene (P-TBT) and p-tert-butylbenzaldehyde (P-TBB). (a) Definitions. (1) P..., CAS No. 98-73-7. (2) P-TBT means the substance p-tert-butyltoluene, also identified as 1-(1,1...

How Alan Hirsig plans to play Arco chemical's strong hand

International Nuclear Information System (INIS)

Hunter, D.

1993-01-01

With 1992 net income up 4%, to $195 million. Arco Chemical (Newtown Square, PA) held its own in a year when many of its petrochemical industry peers were mauled again. Arco Chemical president and CEO Alan R. Hirsig talked recently with CW about his growth strategies for the company, and about progress with his Manufacturing Excellence initiative, lauched in the wake of the 1990 Channelview, TX tragedy. Riding on faster growth in the Asia region, Hirsig expects to see Arco's regional sales mix shift in the next three years and sales to grow from 1992's $3.1 billion to $4 billion/year. The foundation for that growth continues to be Arco's core proprietary technology competence for making propylene oxide (PO) with coproduction and tert-butyl alcohol (TBA) - the key methyl tert-butyl ether (MTBE) feedstock, or styrene monomer. Arco claims a 28% share of world MTBE capacity, its 78,500-bbl/day capacity. He cites Jakarta, Bangkok, Mexico City, Milan, Turin, and Athens as examples of major cities where MTBE use in reformulated fuels is getting interest. Given what he views as Europe's traditional 10-year lag on the US in areas like catalytic mufflers and unleaded gasoline, he sees significant prospects in reformulated gasoline in that region in the coming years. Arco is also testing a proprietary TBA-based hydroperoxide in diesel fuels, which improves the cetane number and cleans up exhaust emissions, winning great interest in Tokyo. Also in the fuels area, Hirsig notes interest in ethyl tert-butyl ether production - which Arco launched in the US in December on a commercial scale - in France

Protective Effects of Cultivated Ginseng, Cultivated Wild Ginseng of Korean and Chinese Against CCl4 and t-BHP Induced Acute Hepatotoxicity in ICR Mice

Directory of Open Access Journals (Sweden)

Kim, Young-Jin

2007-02-01

Full Text Available Objectives : This study was aimed at investigating live protection mechanism of Cultivated Ginseng and Cultivated Wild Ginseng of Korean and Chinese by inducing liver toxicity through and t-BHP in mice and evaluated serological findings. Methods : Experiment groups was categorized into untreated normal group, treated control group, and orally administered Cultivated Ginseng and Cultivated Wild Ginseng of Korean and Chinese experimental groups. At the termination of experiment, gross examination of the liver as well as Total bilirubin, AST, and ALT contents in the serum were evaluated. Results : 1. In the induced acute hepatotoxicity test, total bilirubin, AST and ALT didn't show significant differences between the control and experimental groups. 2. In the t-BHP induced acute hepatotoxicity test, total bilirubin, AST and ALT didn't show significant differences between the control and experimental groups. Conclusion : Taken together, Cultivated Ginseng and Cultivated Wild Ginseng of Korean and Chinese cannot be effectively used for recovering the liver functions in acute hepatotoxicity tests using and t-BHP. Further researches, for example treated long period, must be tried to verify the efficacies.

Molecular structure, vibrational, UV, NMR, HOMO-LUMO, MEP, NLO, NBO analysis of 3,5 di tert butyl 4 hydroxy benzoic acid

Science.gov (United States)

Mathammal, R.; Sangeetha, K.; Sangeetha, M.; Mekala, R.; Gadheeja, S.

2016-09-01

In this study, we report a combined experimental and theoretical study on molecular structure and vibrational spectra of 3,5 di tert butyl 4 hydroxy benzoic acid. The properties of title compound have been evaluated by quantum chemical calculation (DFT) using B3LYP functional and 6-31 + G (d, p) as basis set. IR Spectra has been recorded using Fourier transform infrared spectroscopy (FT-IR) in the region 4000-400 cm-1. The vibrational assignment of the calculated normal modes has been made on the basis set. The isotropic chemical shifts computed by 13C and 1H NMR (Nuclear Magnetic Resonance) analyses also show good agreement with experimental observations. The theoretical UV-Vis spectrum of the compound are used to study the visible absorption maxima (λ max). The structure activity relationship have been interpreted by mapping electrostatic potential surface (MEP), which is valuable information for the quality control of medicines and drug receptor interactions. The Mullikan charges, HOMO (Highest Occupied Molecular Orbital) - LUMO (Lowest Unoccupied Molecular Orbital) energy are analyzed. HOMO-LUMO energy gap and other related molecular properties are also calculated. The Natural Bond Orbital (NBO) analysis is carried out to investigate the various intra and inter molecular interactions of molecular system. The Non-linear optical properties such as dipole moment (μ), polarizability (αtot) and molecular first order hyperpolarizability (β) of the title compound are computed with B3LYP/6-31 + G (d,p) level of theory.

FT-IR and Raman vibrational analysis, B3LYP and M06-2X simulations of 4-bromomethyl-6-tert-butyl-2H-chromen-2-one

Science.gov (United States)

Sert, Yusuf; Puttaraju, K. B.; Keskinoğlu, Sema; Shivashankar, K.; Ucun, Fatih

2015-01-01

In this study, the experimental and theoretical vibrational frequencies of a newly synthesized bacteriostatic and anti-tumor molecule namely, 4-bromomethyl-6-tert-butyl-2H-chromen-2-one have been investigated. The experimental FT-IR (4000-400 cm-1) and Raman spectra (4000-100 cm-1) of the compound in solid phase have been recorded. The theoretical vibrational frequencies and optimized geometric parameters have been calculated using density functional theory (DFT/B3LYP: Becke, 3-parameter, Lee-Yang-Parr and DFT/M06-2X: highly parametrized, empirical exchange correlation function) with 6-311++G(d, p) basis set by Gaussian 03 software, for the first time. The assignments of the vibrational frequencies have been done by potential energy distribution (PED) analysis using VEDA 4 software. The theoretical optimized geometric parameters and vibrational frequencies have been found to be in good agreement with the corresponding experimental data and results in the literature. In addition, the highest occupied molecular orbital (HOMO) energy, the lowest unoccupied molecular orbital (LUMO) energy and the other related molecular energy values of the compound have been investigated using the same theoretical calculations.

γ-aminobutyric acidA (GABAA) receptor regulates ERK1/2 phosphorylation in rat hippocampus in high doses of Methyl Tert-Butyl Ether (MTBE)-induced impairment of spatial memory

International Nuclear Information System (INIS)

Zheng Gang; Zhang Wenbin; Zhang Yun; Chen Yaoming; Liu Mingchao; Yao Ting; Yang Yanxia; Zhao Fang; Li Jingxia; Huang Chuanshu; Luo Wenjing; Chen Jingyuan

2009-01-01

Experimental and occupational exposure to Methyl Tert-Butyl Ether (MTBE) has been reported to induce neurotoxicological and neurobehavioral effects, such as headache, nausea, dizziness, and disorientation, etc. However, the molecular mechanisms involved in MTBE-induced neurotoxicity are still not well understood. In the present study, we investigated the effects of MTBE on spatial memory and the expression and function of GABA A receptor in the hippocampus. Our results demonstrated that intraventricular injection of MTBE impaired the performance of the rats in a Morris water maze task, and significantly increased the expression of GABA A receptor α1 subunit in the hippocampus. The phosphorylation of ERK1/2 decreased after the MTBE injection. Furthermore, the decreased ability of learning and the reduction of phosphorylated ERK1/2 level of the MTBE-treated rats was partly reversed by bicuculline injected 30 min before the training. These results suggested that MTBE exposure could result in impaired spatial memory. GABA A receptor may play an important role in the MTBE-induced impairment of learning and memory by regulating the phosphorylation of ERK in the hippocampus.

Discovery, Synthesis, And Structure-Based Optimization of a Series of N-(tert-Butyl)-2-(N-arylamido)-2-(pyridin-3-yl) Acetamides (ML188) as Potent Noncovalent Small Molecule Inhibitors of the Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) 3CL Protease

Energy Technology Data Exchange (ETDEWEB)

Jacobs, Jon [Vanderbilt Univ., Nashville, TN (United States); Vanderbilt Specialized Chemistry Center for Probe Development (MLPCN), Nashville, TN (United States); Grum-Tokars, Valerie [Northwestern Univ., Chicago, IL (United States); Zhou, Ya [Vanderbilt Univ., Nashville, TN (United States); Vanderbilt Specialized Chemistry Center for Probe Development (MLPCN), Nashville, TN (United States); Turlington, Mark [Vanderbilt Univ., Nashville, TN (United States); Vanderbilt Specialized Chemistry Center for Probe Development (MLPCN), Nashville, TN (United States); Saldanha, S. Adrian [Sripps Research Inst. Molecular Screening Center, Jupiter, FL (United States); Chase, Peter [Sripps Research Inst. Molecular Screening Center, Jupiter, FL (United States); Eggler, Aimee [Purdue Univ., West Lafayette, IN (United States); Dawson, Eric S. [Vanderbilt Univ., Nashville, TN (United States); Vanderbilt Specialized Chemistry Center for Probe Development (MLPCN), Nashville, TN (United States); Baez-Santos, Yahira M. [Purdue Univ., West Lafayette, IN (United States); Tomar, Sakshi [Purdue Univ., West Lafayette, IN (United States); Mielech, Anna M. [Loyola Univ. Medical Center, Maywood, IL (United States); Baker, Susan C. [Loyola Univ. Medical Center, Maywood, IL (United States); Lindsley, Craig W. [Vanderbilt Univ., Nashville, TN (United States); Vanderbilt Specialized Chemistry Center for Probe Development (MLPCN), Nashville, TN (United States); Hodder, Peter [Sripps Research Inst. Molecular Screening Center, Jupiter, FL (United States); Mesecar, Andrew [Purdue Univ., West Lafayette, IN (United States); Stauffer, Shaun R. [Vanderbilt Univ., Nashville, TN (United States); Vanderbilt Specialized Chemistry Center for Probe Development (MLPCN), Nashville, TN (United States)

2012-12-11

A high-throughput screen of the NIH molecular libraries sample collection and subsequent optimization of a lead dipeptide-like series of severe acute respiratory syndrome (SARS) main protease (3CLpro) inhibitors led to the identification of probe compound ML188 (16-(R), (R)-N-(4-(tert-butyl)phenyl)-N-(2-(tert-butylamino)-2-oxo-1-(pyridin-3-yl)ethyl)furan-2-carboxamide, Pubchem CID: 46897844). But, unlike the majority of reported coronavirus 3CLpro inhibitors that act via covalent modification of the enzyme, 16-(R) is a noncovalent SARS-CoV 3CLpro inhibitor with moderate MW and good enzyme and antiviral inhibitory activity. A multicomponent Ugi reaction was utilized to rapidly explore structure–activity relationships within S1', S1, and S2enzyme binding pockets. Moreover, the X-ray structure of SARS-CoV 3CLpro bound with 16-(R) was instrumental in guiding subsequent rounds of chemistry optimization. 16-(R) provides an excellent starting point for the further design and refinement of 3CLpro inhibitors that act by a noncovalent mechanism of action.

Exposure to methyl tert-butyl ether, benzene, and total hydrocarbons at the Singapore-Malaysia causeway immigration checkpoint

Energy Technology Data Exchange (ETDEWEB)

Tan, C.; Ong, H.Y.; Kok, P.W. [and others

1996-12-31

The primary aim of this study was to determine the extent and levels of exposure to volatile organic compounds (VOCs) from automobile emissions in a group of immigration officers at a busy cross-border checkpoint. A majority (80%) of the workers monitored were exposed to benzene at levels between 0.01 and 0.5 ppm, with only 1.2% exceeding the current Occupational Safety and Health Administration occupational exposure limit of 1 ppm. The geometric mean (GM) concentrations of 8-hr time-weighted average exposure were 0.03 ppm, 0.9 ppm, and 2.46 ppm for methyl-tert-butyl ether (MTBE), benzene, and total hydrocarbons (THC), respectively. The highest time-weighted average concentrations measured were 1.05 ppm for MTBE, 2.01 ppm for benzene, and 34 ppm for THC. It was found that motorbikes emitted a more significant amount of pollutants compared with motor cars. On average, officers at the motorcycle booths were exposed to four to five times higher levels of VOCs (GMs of 0.07 ppm, 0.23 ppm, and 4.7 ppm for MTBE, benzene, and THC) than their counterparts at the motor car booths (GMs of 0.01 ppm, 0.05 ppm, and 1.5 ppm). The airborne concentrations of all three pollutants correlated with the flow of vehicle traffic. Close correlations were also noted for the concentrations in ambient air for the three pollutants measured. Benzene and MTBE had a correlation coefficient of 0.97. The overall findings showed that the concentrations of various VOCs were closely related to the traffic density, suggesting that they were from a common source, such as exhaust emissions from the vehicles. The results also indicated that although benzene, MTBE, and THC are known to be volatile, a significant amount could still be detected in the ambient environment, thus contributing to our exposure to these compounds. 4 refs., 6 figs.

The beneficial effects of mixing spiro-OMeTAD with n-butyl-substituted copper phthalocyanine for perovskite solar cells

International Nuclear Information System (INIS)

Nouri, Esmaiel; Wang, Yu-Long; Chen, Qian; Xu, Jia-Ju; Dracopoulos, Vassilios; Sygellou, Lamprini; Xu, Zong-Xiang; Mohammadi, Mohammad Reza; Lianos, Panagiotis

2016-01-01

Highlights: • Soluble n-butyl substituted copper phthalocyanine. • Mixture with spiro-OMeTAD and employment in perovskite solar cells. • Impressive improvement of perovskite solar cell efficiency. • n-Butyl derivative gives better results than tert-butyl derivative - Abstract: Perovskite solar cells have been constructed under ambient conditions by using 2,2',7,7'-Tetrakis-(N,N-di-4-methoxyphenylamino)-9,9'-spirobifluorene (spiro-OMeTAD) mixed with a small quantity of soluble tetra-n-butyl substituted copper phthalocyanine as hole transporting material. The introduction of the phthalocyanine derivative resulted in an impressive increase of cell efficiency, which changed from 10.4% in the absence to 15.4% in the presence of phthalocyanine. This effect is related to the creation of deep traps in the hole transporting phase which block back-travelling electrons as well as to the improvement of the structural quality of the spiro-OMeTAD film in the presence of phthalocyanine. Both functionalities decrease shunt paths within the hole transporting phase resulting in increasing the fill factor and the open-circuit voltage of the cell.

Licochalcone A Upregulates Nrf2 Antioxidant Pathway and Thereby Alleviates Acetaminophen-Induced Hepatotoxicity

Directory of Open Access Journals (Sweden)

Hongming Lv

2018-03-01

Full Text Available Acetaminophen (APAP overdose-induced fatal hepatotoxicity is majorly characterized by overwhelmingly increased oxidative stress while enhanced nuclear factor-erythroid 2-related factor 2 (Nrf2 is involved in prevention of hepatotoxicity. Although Licochalcone A (Lico A upregulates Nrf2 signaling pathway against oxidative stress-triggered cell injury, whether it could protect from APAP-induced hepatotoxicity by directly inducing Nrf2 activation is still poorly elucidated. This study aims to explore the protective effect of Lico A against APAP-induced hepatotoxicity and its underlying molecular mechanisms. Our findings indicated that Lico A effectively decreased tert-butyl hydroperoxide (t-BHP- and APAP-stimulated cell apoptosis, mitochondrial dysfunction and reactive oxygen species generation and increased various anti-oxidative enzymes expression, which is largely dependent on upregulating Nrf2 nuclear translocation, reducing the Keap1 protein expression, and strengthening the antioxidant response element promoter activity. Meanwhile, Lico A dramatically protected against APAP-induced acute liver failure by lessening the lethality; alleviating histopathological liver changes; decreasing the alanine transaminase and aspartate aminotransferase levels, malondialdehyde formation, myeloperoxidase level and superoxide dismutase depletion, and increasing the GSH-to-GSSG ratio. Furthermore, Lico A not only significantly modulated apoptosis-related protein by increasing Bcl-2 expression, and decreasing Bax and caspase-3 cleavage expression, but also efficiently alleviated mitochondrial dysfunction by reducing c-jun N-terminal kinase phosphorylation and translocation, inhibiting Bax mitochondrial translocation, apoptosis-inducing factor and cytochrome c release. However, Lico A-inhibited APAP-induced the lethality, histopathological changes, hepatic apoptosis, and mitochondrial dysfunction in WT mice were evidently abrogated in Nrf2-/- mice. These

Cyclopentadienyl molybdenum(II/VI) N-heterocyclic carbene complexes: Synthesis, structure, and reactivity under oxidative conditions

KAUST Repository

Li, Shenyu

2010-04-26

A series of N-heterocyclic carbene (NHC) complexes CpMo(CO) 2(NHC)X (NHC = IMe = 1,3-dimethylimidazol-2-ylidene, X = Br, 1; NHC = 1,3-dipropylimidazol-2-ylidene, X = Br, 2; NHC = IMes = 1,3-bis(2,4,6- trimethylphenyl)imidazol-2-ylidene, X = Br, 3; NHC = IBz = 1,3-dibenzylimidazol- 2-ylidene, X = Br, 4a, and X = Cl, 4b; NHC = 1-methyl-3-propylimidazol-2- ylidene, X = Br, 5) and [CpMo(CO)2(IMes)(CH3CN)][BF 4] (6) have been synthesized and fully characterized. The stability of metal-NHC ligand bonds in these compounds under oxidative conditions has been investigated. The thermally stable Mo(VI) dioxo NHC complex [CpMoO 2(IMes)][BF4] (9) has been isolated by the oxidation of the ionic complex 6 by TBHP (tert-butyl hydrogen peroxide). Complex 6 can be applied as a very active (TOFs up to 3400 h-1) and selective olefin epoxidation catalyst. While under oxidative conditions (in the presence of TBHP), compounds 1-5 decompose into imidazolium bromide and imidazolium polyoxomolybdate. The formation of polyoxomolybdate as oxidation products had not been observed in a similar epoxidation catalyzed by Mo(II) and Mo(VI) complexes. DFT studies suggest that the presence of Br- destabilizes the CpMo(VI) oxo NHC carbene species, consistent with the experimental observations. © 2010 American Chemical Society.

SIRT1 exhibits antioxidative effects in HT22 cells induced by tert-butyl alcohol.

Science.gov (United States)

Ma, Junxiang; Song, Dongmei; Zhang, Yuanyuan; Chen, Li; Zhang, Shixuan; Jia, Jiaxin; Chen, Tian; Guo, Caixia; Tian, Lin; Gao, Ai; Niu, Piye

2018-02-01

Tertiary butyl alcohol (TBA) is a principal metabolite of methyl tertiary-butyl ether (MTBE), a common pollutant worldwide in the ground or underground water, which is found to produce nervous system damage. Nevertheless, few data regarding the effects of TBA has been reported. Studies indicated that oxidative stress plays a pivotal role in MTBE neurotoxic mechanism. Sirtuin 1 (SIRT1) has been reported to exert a neuroprotective effect on various neurologic diseases via resistance to oxidative stress by deacetylating its substrates. In this study, we examined levels of oxidative stress after exposure to TBA for 6 h in HT22 cells and HT22 cells with SIRT1 silencing (transfected with SIRT1 siRNA) or high expression (preconditioned with agonists SRT1720). We found that TBA activated oxidative stress by increasing generation of intracellular reactive oxygen species (ROS), malondialdehyde (MDA) and Oxidized glutathione (GSSG), and decreasing contents of superoxide dismutase (SOD) and glutathione reductase (GSH). In additional, levels of TBA-induced oxidative stress were aggravated when SIRT1 silenced but alleviated when SIRT1 enhanced. Our study indicated that SIRT1 mitigated oxidative stress induced by TBA. © 2017 Wiley Periodicals, Inc.

Evaluation of ethyl tert-butyl ether biodegradation in a contaminated aquifer by compound-specific isotope analysis and in situ microcosms

Energy Technology Data Exchange (ETDEWEB)

Bombach, Petra, E-mail: petra.bombach@ufz.de [UFZ – Helmholtz Centre for Environmental Research, Department of Isotope Biogeochemistry, Permoserstrasse 15, D-04318 Leipzig (Germany); Isodetect GmbH Leipzig, Deutscher Platz 5b, D-04103 Leipzig (Germany); Nägele, Norbert [Kuvier the Biotech Company S.L., Ctra. N-I, p.k. 234–P.E. INBISA 23" a, E-09001 Burgos (Spain); Rosell, Mònica [UFZ – Helmholtz Centre for Environmental Research, Department of Isotope Biogeochemistry, Permoserstrasse 15, D-04318 Leipzig (Germany); Grup de Mineralogia Aplicada i Medi Ambient, Departament de Cristallografia, Mineralogia i Dipòsits Minerals, Facultat de Geologia, Universitat de Barcelona (UB), C/Martí i Franquès s/n, 08028 Barcelona (Spain); Richnow, Hans H. [UFZ – Helmholtz Centre for Environmental Research, Department of Isotope Biogeochemistry, Permoserstrasse 15, D-04318 Leipzig (Germany); Fischer, Anko [Isodetect GmbH Leipzig, Deutscher Platz 5b, D-04103 Leipzig (Germany)

2015-04-09

Highlights: • In situ biodegradation of ETBE was investigated in a fuel contaminated aquifer. • Degradation was studied by CSIA and in situ microcosms in combination with TLFA-SIP. • ETBE was degraded when ETBE was the main groundwater contaminant. • ETBE was also degraded in the presence of BTEX and MTBE. • Hydrochemical analysis indicated aerobic and anaerobic ETBE biodegradation. - Abstract: Ethyl tert-butyl ether (ETBE) is an upcoming groundwater pollutant in Europe whose environmental fate has been less investigated, thus far. In the present study, we investigated the in situ biodegradation of ETBE in a fuel-contaminated aquifer using compound-specific stable isotope analysis (CSIA), and in situ microcosms in combination with total lipid fatty acid (TLFA)-stable isotope probing (SIP). In a first field investigation, CSIA revealed insignificant carbon isotope fractionation, but low hydrogen isotope fractionation of up to +14‰ along the prevailing anoxic ETBE plume suggesting biodegradation of ETBE. Ten months later, oxygen injection was conducted to enhance the biodegradation of petroleum hydrocarbons (PH) at the field site. Within the framework of this remediation measure, in situ microcosms loaded with [{sup 13}C{sub 6}]-ETBE (BACTRAP{sup ®}s) were exposed for 119 days in selected groundwater wells to assess the biodegradation of ETBE by TLFA-SIP under the following conditions: (i) ETBE as main contaminant; (ii) ETBE as main contaminant subjected to oxygen injection; (iii) ETBE plus other PH; (iv) ETBE plus other PH subjected to oxygen injection. Under all conditions investigated, significant {sup 13}C-incorporation into microbial total lipid fatty acids extracted from the in situ microcosms was found, providing clear evidence of ETBE biodegradation.

Electronic structure and electron dynamics at an organic molecule/metal interface: interface states of tetra-tert-butyl-imine/Au(111)

International Nuclear Information System (INIS)

Hagen, Sebastian; Wolf, Martin; Tegeder, Petra; Luo Ying; Haag, Rainer

2010-01-01

Time- and angle-resolved two-photon photoemission (2PPE) spectroscopies have been used to investigated the electronic structure, electron dynamics and localization at the interface between tetra-tert-butyl imine (TBI) and Au(111). At a TBI coverage of one monolayer (ML), the two highest occupied molecular orbitals, HOMO and HOMO-1, are observed at an energy of -1.9 and -2.6 eV below the Fermi level (E F ), respectively, and coincide with the d-band features of the Au substrate. In the unoccupied electronic structure, the lowest unoccupied molecular orbital (LUMO) has been observed at 1.6 eV with respect to E F . In addition, two delocalized states that arise from the modified image potential at the TBI/metal interface have been identified. Their binding energies depend strongly on the adsorption structure of the TBI adlayer, which is coverage dependent in the submonolayer (≤1 ML) regime. Thus the binding energy of the lower interface state (IS) shifts from 3.5 eV at 1.0 ML to 4.0 eV at 0.5 ML, which is accompanied by a pronounced decrease in its lifetime from 100 fs to below 10 fs. This is a result of differences in the wave function overlap with electronic states of the Au(111) substrate at different binding energies. This study shows that in order to fully understand the electronic structure of organic adsorbates at metal surfaces, not only adsorbate- and substrate-induced electronic states have to be considered but also ISs, which are the result of a potential formed by the interaction between the adsorbate and the substrate.

Evaluation of ethyl tert-butyl ether biodegradation in a contaminated aquifer by compound-specific isotope analysis and in situ microcosms

International Nuclear Information System (INIS)

Bombach, Petra; a, E-09001 Burgos (Spain))" data-affiliation=" (Kuvier the Biotech Company S.L., Ctra. N-I, p.k. 234–P.E. INBISA 23a, E-09001 Burgos (Spain))" >Nägele, Norbert; Rosell, Mònica; Richnow, Hans H.; Fischer, Anko

2015-01-01

Highlights: • In situ biodegradation of ETBE was investigated in a fuel contaminated aquifer. • Degradation was studied by CSIA and in situ microcosms in combination with TLFA-SIP. • ETBE was degraded when ETBE was the main groundwater contaminant. • ETBE was also degraded in the presence of BTEX and MTBE. • Hydrochemical analysis indicated aerobic and anaerobic ETBE biodegradation. - Abstract: Ethyl tert-butyl ether (ETBE) is an upcoming groundwater pollutant in Europe whose environmental fate has been less investigated, thus far. In the present study, we investigated the in situ biodegradation of ETBE in a fuel-contaminated aquifer using compound-specific stable isotope analysis (CSIA), and in situ microcosms in combination with total lipid fatty acid (TLFA)-stable isotope probing (SIP). In a first field investigation, CSIA revealed insignificant carbon isotope fractionation, but low hydrogen isotope fractionation of up to +14‰ along the prevailing anoxic ETBE plume suggesting biodegradation of ETBE. Ten months later, oxygen injection was conducted to enhance the biodegradation of petroleum hydrocarbons (PH) at the field site. Within the framework of this remediation measure, in situ microcosms loaded with [ 13 C 6 ]-ETBE (BACTRAP ® s) were exposed for 119 days in selected groundwater wells to assess the biodegradation of ETBE by TLFA-SIP under the following conditions: (i) ETBE as main contaminant; (ii) ETBE as main contaminant subjected to oxygen injection; (iii) ETBE plus other PH; (iv) ETBE plus other PH subjected to oxygen injection. Under all conditions investigated, significant 13 C-incorporation into microbial total lipid fatty acids extracted from the in situ microcosms was found, providing clear evidence of ETBE biodegradation

tert-Butyl 6-bromo-1,4-dimethyl-9H-carbazole-9-carboxylate

Directory of Open Access Journals (Sweden)

Jean-François Lohier

2010-08-01

Full Text Available The title compound, C19H20BrNO2, consists of a carbazole skeleton with methyl groups at positions 1 and 4, a protecting group located at the N atom and a Br atom at position 6. The pyrrole ring is oriented at dihedral angles of 1.27 (7 and 4.86 (7° with respect to the adjacent benzene rings. The dihedral angle between the benzene rings is 5.11 (7. The crystal structure is determined mainly by intramolecular C—H...O and intermolecular π–π interactions. π-stacking between adjacent molecules forms columns with a parallel arrangement of the carbazole ring systems. The presence of the tert-butoxycarbonyl group on the carbazole N atom and the intramolecular hydrogen bond induce a particular conformation of the exocyclic N—C bond within the molecule.

Antioxidant effect of bisphosphonates and simvastatin on chondrocyte lipid peroxidation

International Nuclear Information System (INIS)

Dombrecht, E.J.; De Tollenaere, C.B.; Aerts, K.; Cos, P.; Schuerwegh, A.J.; Bridts, C.H.; Van Offel, J.F.; Ebo, D.G.; Stevens, W.J.; De Clerck, L.S.

2006-01-01

The objective of this study was to evaluate the effect of bisphosphonates (BPs) and simvastatin on chondrocyte lipid peroxidation. For this purpose, a flow cytometrical method using C11-BODIPY 581/591 was developed to detect hydroperoxide-induced lipid peroxidation in chondrocytes. Tertiary butylhydroperoxide (t-BHP) induced a time and concentration dependent increase in chondrocyte lipid peroxidation. Addition of a Fe 2+ /EDTA complex to t-BHP or hydrogen peroxide (H 2 O 2 ) clearly enhanced lipid peroxidation. The lipophilic simvastatin demonstrated a small inhibition in the chondrocyte lipid peroxidation. None of three tested BPs (clodronate, pamidronate, and risedronate) had an effect on chondrocyte lipid peroxidation induced by t-BHP. However, when Fe 2+ /EDTA complex was added to t-BHP or H 2 O 2 , BPs inhibited the lipid peroxidation process varying from 25% to 58%. This study demonstrates that BPs have antioxidant properties as iron chelators, thereby inhibiting the chondrocyte lipid peroxidation. These findings add evidence to the therapeutic potential of bisphosphonates and statins in rheumatoid arthritis

Synthesis and complexation properties towards uranyl cation of carboxylic acid derivatives of p-tert-butyl-calix[6]arene; Synthese et proprietes complexantes vis-a-vis de l'ion uranyle de derives carboxyliques du p-tert-butyl-calix[6]arene

Energy Technology Data Exchange (ETDEWEB)

Souane, R

2005-03-15

In the fuel reprocessing plants radioactive metals, and more particularly, uranium in UO{sub 2}{sup 2+} form in the various installations, have many varied physico-chemical forms and there is a risk of exposure and internal contamination in the nuclear industry. It is necessary to exert a medical control to ensure the protection of the health of the workers. This medical control is done by dosing uranyl cation in the urine of the exposed people. This work forms part of this context. Indeed, we prepared a ligand able to complex the ion uranyl and which is also to be grafted on a solid support. In the family of calixarenes, the calix[6]arenes functionalized by three or four carboxylic functions were selected like chelating molecules of the ion uranyl. The properties of complexation of these calixarenes were studied by potentiometry in methanol, under these conditions balances of protonation and complexation were determined and the constant partners were obtained using the Hyperquad program. We synthesized tri-carboxylic calix[6]arenes comprising of the groupings nitro (NO{sub 2}) in para position of phenol in order to see the influence of a substitution in para position on the complexation. We also synthesized calix[6]arenes tetra-carboxylic in order to show the role of an additional carboxylic acid grouping. The potentiometric study determined thermodynamic parameters of protonation and complexation of carboxylic calix[6]arenes. The results of the complexation highlighted which complex UO{sub 2}L corresponding to the ligand para-tert-butyl-calix[6]arene tetra-acid is more stable than that corresponding to the ligand mono-nitro calix[6]arene tri-acid ({delta}log{beta}110 = 4.3), and than the effect of the groupings nitro in para position has low influence on the complexation of UO{sub 2}{sup 2+}. This makes it possible to consider as possible the grafting of the calix[6]arenes which one knows the behaviour of trapping. To this end we synthesized the ligand 23

Ternary catalyst-olefin-hydroperoxide complexes and their contribution to epoxidation

International Nuclear Information System (INIS)

Svitych, R.B.; Rzhevskaya, N.N.; Buchachenko, A.L.; Yablonskij, O.P.; Petukhov, A.A.; Belyaev, V.A.

1976-01-01

Electron and NMR spectroscopy have been used for studying the complex formation of catalysts (Mo 5+ , Mn 2+ , Co 2+ ) in double and triple systems: metal-olefin and metal-olefin-hydroperoxide. It has been established that ions of metals form complexes with olefins in the first sphere. The formation has been proved of ternary complexes metal-olefin-hydroperoxide. The structure of the complexes has been proposed with olefins in the first and hydroperoxide in the second sphere of the metal ion. The structure explains known kinetic regularities of epoxydation and the mechanism of the formation of final products, oxide and alcohol. It has been shown that the best catalysts for epoxydation of olefins with hydroperoxides must be the compounds of the metals with an electron state of ion d 0 [ru

Relation between photochromic properties and molecular structures in salicylideneaniline crystals.

Science.gov (United States)

Johmoto, Kohei; Ishida, Takashi; Sekine, Akiko; Uekusa, Hidehiro; Ohashi, Yuji

2012-06-01

The crystal structures of the salicylideneaniline derivatives N-salicylidene-4-tert-butyl-aniline (1), N-3,5-di-tert-butyl-salicylidene-3-methoxyaniline (2), N-3,5-di-tert-butyl-salicylidene-3-bromoaniline (3), N-3,5-di-tert-butyl-salicylidene-3-chloroaniline (4), N-3,5-di-tert-butyl-salicylidene-4-bromoaniline (5), N-3,5-di-tert-butyl-salicylidene-aniline (6), N-3,5-di-tert-butyl-salicylidene-4-carboxyaniline (7) and N-salicylidene-2-chloroaniline (8) were analyzed by X-ray diffraction analysis at ambient temperature to investigate the relationship between their photochromic properties and molecular structures. A clear correlation between photochromism and the dihedral angle of the two benzene rings in the salicylideneaniline derivatives was observed. Crystals with dihedral angles less than 20° were non-photochromic, whereas those with dihedral angles greater than 30° were photochromic. Crystals with dihedral angles between 20 and 30° could be either photochromic or non-photochromic. Inhibition of the pedal motion by intra- or intermolecular steric hindrance, however, can result in non-photochromic behaviour even if the dihedral angle is larger than 30°.

Polyisoprene Nanoparticles Prepared by Polymerization in Microemulsion

Directory of Open Access Journals (Sweden)

Y. Apolinar

2010-01-01

Full Text Available Batch polymerization of isoprene was carried out at 25∘C in a normal microemulsion stabilized with sodium dodecyl sulfate and initiated with the redox couple tert-butyl hydroperoxide/tetraethylene-pentamine. Characterization by transmission electronic microscopy showed that polyisoprene nanoparticles with number-average diameter close to 20 nm were obtained. The low molecular weights obtained, as determined by gel permeation chromatography, were probably due to chain scission as inferred from the oxidative ambient at which polymerization was carried out. Microstructure calculated from infrared spectroscopy data indicates that the obtained polyisoprene contains around 80% total 1,4 units, which is in accordance with its glass transition temperature (-60.8∘C determined by differential scanning calorimetry.

Aerobic degradation of methyl tert-butyl ether in a closed symbiotic system containing a mixed culture of Chlorella ellipsoidea and Methylibium petroleiphilum PM1.

Science.gov (United States)

Zhong, Weihong; Li, Yixiao; Sun, Kedan; Jin, Jing; Li, Xuanzhen; Zhang, Fuming; Chen, Jianmeng

2011-01-30

The contamination of groundwater by methyl tert-butyl ether (MTBE) is one of the most serious environmental problems around the world. MTBE degradation in a closed algal-bacterial symbiotic system, containing a mixed culture of Methylibium petroleiphilum PM1 and Chlorella ellipsoidea, was investigated. The algal-bacterial symbiotic system showed increased MTBE degradation. The MTBE-degradation rate in the mixed culture (8.808 ± 0.007 mg l(-1) d(-1)) was higher than that in the pure bacterial culture (5.664 ± 0.017 mg l(-1) d(-1)). The level of dissolved oxygen was also higher in the mixed culture than that in the pure bacterial culture. However, the improved efficiency of MTBE degradation was not in proportional to the biomass of the alga. The optimal ratio of initial cell population of bacteria to algae was 100:1. An immobilized culture of mixed bacteria and algae also showed higher MTBE degradation rate than the immobilized pure bacterial culture. A mixed culture with algae and PM1 immobilized separately in different gel beads showed higher degradation rate (8.496 ± 0.636 mg l(-1) d(-1)) than that obtained with algae and PM1 immobilized in the same gel beads (5.424 ± 0.010 mg l(-1) d(-1)). Copyright © 2010 Elsevier B.V. All rights reserved.

Anaerobic degradation of a mixture of MtBE, EtBE, TBA, and benzene under different redox conditions

NARCIS (Netherlands)

Waals, van der Marcelle J.; Pijls, Charles; Sinke, Anja J.C.; Langenhoff, Alette A.M.; Smidt, Hauke; Gerritse, Jan

2018-01-01

The increasing use of biobased fuels and fuel additives can potentially change the typical fuel-related contamination in soil and groundwater. Anaerobic biotransformation of the biofuel additive ethyl tert-butyl ether (EtBE), as well as of methyl tert-butyl ether (MtBE), benzene, and tert-butyl

Fatty acid hydroperoxides pathways in plants. A review.

Directory of Open Access Journals (Sweden)

Fauconnier, M. L.

1997-02-01

Full Text Available The present paper focusses on the fatty acid hydroperoxides pathways, mainly hydroperoxide lyase and hydroperoxide dehydrase. For each enzyme, the definition, occurrence and subcellular localization is presented. Particular attention is given to reaction mecanisms and to substrate specificity. Physiological roles of reaction products are also discussed.

El presente artículo se centra en las rutas de los hidroperóxidos de ácidos grasos, principalmente la hidroperóxido liasa y la hidroperóxido dehidrasa. Se presenta para cada enzima, la definición, distribución y localización subcelular. Se da atención particular a los mecanismos de reacción y a la especificidad de sustrato. También se discuten los papeles fisiológicos de los productos de reacción.

Resistance to organic hydroperoxides requires ohr and ohrR genes in Sinorhizobium meliloti

Directory of Open Access Journals (Sweden)

Dufour Virginie

2011-05-01

Full Text Available Abstract Background Sinorhizobium meliloti is a symbiotic nitrogen-fixing bacterium that elicits nodules on roots of host plants Medicago sativa. During nodule formation bacteria have to withstand oxygen radicals produced by the plant. Resistance to H2O2 and superoxides has been extensively studied in S. meliloti. In contrast resistance to organic peroxides has not been investigated while S. meliloti genome encodes putative organic peroxidases. Organic peroxides are produced by plants and are highly toxic. The resistance to these oxygen radicals has been studied in various bacteria but never in plant nodulating bacteria. Results In this study we report the characterisation of organic hydroperoxide resistance gene ohr and its regulator ohrR in S. meliloti. The inactivation of ohr affects resistance to cumene and ter-butyl hydroperoxides but not to hydrogen peroxide or menadione in vitro. The expression of ohr and ohrR genes is specifically induced by organic peroxides. OhrR binds to the intergenic region between the divergent genes ohr and ohrR. Two binding sites were characterised. Binding to the operator is prevented by OhrR oxidation that promotes OhrR dimerisation. The inactivation of ohr did not affect symbiosis and nitrogen fixation, suggesting that redundant enzymatic activity exists in this strain. Both ohr and ohrR are expressed in nodules suggesting that they play a role during nitrogen fixation. Conclusions This report demonstrates the significant role Ohr and OhrR proteins play in bacterial stress resistance against organic peroxides in S. meliloti. The ohr and ohrR genes are expressed in nodule-inhabiting bacteroids suggesting a role during nodulation.

Radicals derived from histone hydroperoxides damage nucleobases in RNA and DNA

DEFF Research Database (Denmark)

Luxford, C; Dean, R T; Davies, Michael Jonathan

2000-01-01

Exposure of individual histone proteins (H1, H2A, H2B, H3, or H4) and histone octamers (consisting of two molecules each of H2A, H2B, H3, and H4) to hydroxyl radicals, generated by gamma-irradiation, in the presence of O(2) generates protein-bound hydroperoxides in a dose-dependent fashion......; this is in accord with previous studies with other proteins. These histone hydroperoxides are stable in the absence of exogenous catalysts (e.g., heat, light, and transition metal ions), but in the presence of these agents decompose rapidly to give a variety of radicals which have been identified by EPR spin...... trapping. Histone hydroperoxide-derived radicals generated on decomposition of the hydroperoxides with Cu(+) react with both pyrimidine and purine nucleobases. Thus, with uridine the histone hydroperoxide-derived radicals undergo addition across the C(5)-C(6) double bond of the pyrimidine ring to give...

Contact Allergy to Hydroperoxides of Linalool and D-Limonene in a US Population.

Science.gov (United States)

Nath, Neel Som; Liu, Beiyu; Green, Cynthia; Atwater, Amber Reck

Linalool and D-limonene are common fragrance ingredients that readily oxidize on exposure to air. The resulting hydroperoxides of linalool and D-limonene have been shown to have high frequencies of positive patch test reactions in several European and international studies. The aim of the study was to investigate the prevalence of contact allergy to the hydroperoxides of linalool and D-limonene in a US population. In this retrospective study, 103 patients with suspected fragrance allergy were patch tested to linalool 10% petrolatum (pet), hydroperoxides of linalool 1% pet, D-limonene 10% pet, and/or the hydroperoxides of D-limonene 0.3% pet between July 9, 2014, and October 25, 2016. In this study, the frequency of positive patch test reactions to the hydroperoxides of linalool is 20% (19/96), and the frequency of positive reactions to the hydroperoxides of D-limonene is 8% (7/90). These high frequencies suggest that patch testing to the hydroperoxides of linalool and limonene should be performed in all patients with suspected fragrance allergy.

Synthesis and complexation properties towards uranyl cation of carboxylic acid derivatives of p-tert-butyl-calix[6]arene

International Nuclear Information System (INIS)

Souane, R.

2005-03-01

In the fuel reprocessing plants radioactive metals, and more particularly, uranium in UO 2 2+ form in the various installations, have many varied physico-chemical forms and there is a risk of exposure and internal contamination in the nuclear industry. It is necessary to exert a medical control to ensure the protection of the health of the workers. This medical control is done by dosing uranyl cation in the urine of the exposed people. This work forms part of this context. Indeed, we prepared a ligand able to complex the ion uranyl and which is also to be grafted on a solid support. In the family of calixarenes, the calix[6]arenes functionalized by three or four carboxylic functions were selected like chelating molecules of the ion uranyl. The properties of complexation of these calixarenes were studied by potentiometry in methanol, under these conditions balances of protonation and complexation were determined and the constant partners were obtained using the Hyperquad program. We synthesized tri-carboxylic calix[6]arenes comprising of the groupings nitro (NO 2 ) in para position of phenol in order to see the influence of a substitution in para position on the complexation. We also synthesized calix[6]arenes tetra-carboxylic in order to show the role of an additional carboxylic acid grouping. The potentiometric study determined thermodynamic parameters of protonation and complexation of carboxylic calix[6]arenes. The results of the complexation highlighted which complex UO 2 L corresponding to the ligand para-tert-butyl-calix[6]arene tetra-acid is more stable than that corresponding to the ligand mono-nitro calix[6]arene tri-acid (ΔlogΒ110 = 4.3), and than the effect of the groupings nitro in para position has low influence on the complexation of UO 2 2+ . This makes it possible to consider as possible the grafting of the calix[6]arenes which one knows the behaviour of trapping. To this end we synthesized the ligand 23. (author)

Isolate PM1 populations are dominant and novel methyl tert-butyl ether-degrading bacterial in compost biofilter enrichments.

Science.gov (United States)

Bruns, M A; Hanson, J R; Mefford, J; Scow, K M

2001-03-01

The gasoline additive MTBE, methyl tert-butyl ether, is a widespread and persistent groundwater contaminant. MTBE undergoes rapid mineralization as the sole carbon and energy source of bacterial strain PM1, isolated from an enrichment culture of compost biofilter material. In this report, we describe the results of microbial community DNA profiling to assess the relative dominance of isolate PM1 and other bacterial strains cultured from the compost enrichment. Three polymerase chain reaction (PCR)-based profiling approaches were evaluated: denaturing gradient gel electrophoresis (DGGE) analysis of 230 bp 16S rDNA fragments; thermal gradient gel electrophoresis (TGGE) analysis of 575 bp 16S rDNA fragments; and non-denaturing polyacrylamide gel electrophoresis of 300-1,500 bp fragments containing 16S/23S ribosomal intergenic transcribed spacer (ITS) regions. Whereas all three DNA profiling approaches indicated that PM1-like bands predominated in mixtures from MTBE-grown enrichments, ITS profiling provided the most abundant and specific sequence data to confirm strain PM1's presence in the enrichment. Moreover, ITS profiling did not produce non-specific PCR products that were observed with T/DGGE. A further advantage of ITS community profiling over other methods requiring restriction digestion (e.g. terminal restriction fragment length polymorphisms) was that it did not require an additional digestion step or the use of automated sequencing equipment. ITS bands, excised from similar locations in profiles of the enrichment and PM1 pure culture, were 99.9% identical across 750 16S rDNA positions and 100% identical across 691 spacer positions. BLAST comparisons of nearly full-length 16S rDNA sequences showed 96% similarity between isolate PM1 and representatives of at least four different genera in the Leptothrix subgroup of the beta-Proteobacteria (Aquabacterium, Leptothrix, Rubrivivax and Ideonella). Maximum likelihood and parsimony analyses of 1,249 nucleotide

Vibrational spectra and ab initio analysis of tert-butyl, trimethylsilyl, and trimethylgermyl derivatives of 3,3-dimethylcyclopropene II. 3,3-Dimethyl-1,2-bis(trimethylsilyl)cyclopropene

Science.gov (United States)

Panchenko, Yu. N.; De Maré, G. R.; Abramenkov, A. V.; Baird, M. S.; Tverezovsky, V. V.; Nizovtsev, A. V.; Bolesov, I. G.

2003-07-01

The IR and Raman spectra of 3,3-dimethyl-1,2-bis(trimethylsilyl)cyclopropene (I) (synthesised using standard procedures) were measured in the liquid phase. Total geometry optimisation was performed at the HF/6-31G* level. The HF/6-31G*//HF/6-31G* quantum mechanical force field (QMFF) was calculated and used to determine the theoretical fundamental vibrational frequencies, their predicted IR intensities, Raman activities, and Raman depolarisation ratios. Using Pulay's scaling method and the theoretical molecular geometry, the QMFF of I was scaled by a set of scaling factors used previously for 3,3-dimethyl-1,2-bis(tert-butyl)cyclopropene (17 scale factors for a 105-dimensional problem). The scaled QMFF obtained was used to solve the vibrational problem. The quantum mechanical values of the Raman activities were converted to differential Raman cross sections. The figures for the experimental and theoretical Raman and IR spectra are presented. Assignments of the experimental vibrational spectra of I are given. They take into account the calculated potential energy distribution and the correlation between the estimations of the experimental IR and Raman intensities and Raman depolarisation ratios and the corresponding theoretical values (including Raman cross sections) calculated using the unscaled QMFF.

Vibrational Spectroscopy Investigation Using Ab Initio and Density Functional Theory Analysis on the Structure of tert-Butyl 3a-Chloroperhydro-2,6a-epoxyoxireno[e]isoindole-5-carboxylate

Directory of Open Access Journals (Sweden)

Hakan Arslan

2013-01-01

Full Text Available The molecular structure, vibrational frequencies, and infrared intensities of the tert-butyl 3a-chloroperhydro-2,6a-epoxyoxireno[e]isoindole-5-carboxylate were calculated by the HF and DFT (BLYP and B3LYP methods using 6-31G(d and 6-31G(d,p basis sets. The FT infrared spectrum of the solid sample was measured under standard condition. We obtained two stable conformers for the title compound; however Conformer 1 is approximately 0.2 kcal/mol more stable than the Conformer 2. The comparison of the theoretical and experimental geometry of the title compound shows that the X-ray parameters fairly well reproduce the geometry of Conformer 2. Comparison of the observed fundamental vibrational frequencies of the title molecule and calculated results by HF and DFT methods indicates that B3LYP is superior for molecular vibrational problems. The harmonic vibrations computed by the B3LYP/6-31G(d,p method are in a good agreement with the observed IR spectral data. Theoretical vibrational spectra of the title compound were interpreted by means of potential energy distributions (PEDs using VEDA 4 program.

Investigating the Antioxidant and Acetylcholinesterase Inhibition Activities of Gossypium herbaceam

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Haji Akber Aisa

2013-01-01

Full Text Available Our previous research showed that standardized extract from the flowers of the Gossypium herbaceam labeled GHE had been used in clinical trials for its beneficial effects on brain functions, particularly in connection with age-related dementia and Alzheimer’s disease (AD. The aim of this work was to determine the components of this herb and the individual constituents of GHE. In order to better understand this herb for AD treatment, we investigated the acetylcholinesterase (AChE inhibition and antioxidant activity of GHE as well as the protective effects to PC12 cells against cytotoxicity induced by tertiary butyl hydroperoxide (tBHP using in vitro assays. The antioxidant activities were assessed by measuring their capabilities for scavenging 1,1-diphenyl-2-picylhydrazyl (DPPH and 2-2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS free radical as well as in inhibiting lipid peroxidation. Our data showed that GHE exhibited certain activities against AChE and also is an efficient free radical scavenger, which may be helpful in preventing or alleviating patients suffering from AD.

Anti-Inflammatory Activities of Licorice Extract and Its Active Compounds, Glycyrrhizic Acid, Liquiritin and Liquiritigenin, in BV2 Cells and Mice Liver

Directory of Open Access Journals (Sweden)

Ji-Yeon Yu

2015-07-01

Full Text Available This study provides the scientific basis for the anti-inflammatory effects of licorice extract in a t-BHP (tert-butyl hydrogen peroxide-induced liver damage model and the effects of its ingredients, glycyrrhizic acid (GA, liquiritin (LQ and liquiritigenin (LG, in a lipopolysaccharide (LPS-stimulated microglial cell model. The GA, LQ and LG inhibited the LPS-stimulated elevation of pro-inflammatory mediators, such as inducible nitric oxide synthase (iNOS, cyclooxygenase-2 (COX-2, tumor necrosis factor (TNF-alpha, interleukin (IL-1beta and interleukin (IL-6 in BV2 (mouse brain microglia cells. Furthermore, licorice extract inhibited the expression levels of pro-inflammatory cytokines (TNF-α, IL-1β and IL-6 in the livers of t-BHP-treated mice models. This result suggested that mechanistic-based evidence substantiating the traditional claims of licorice extract and its three bioactive components can be applied for the treatment of inflammation-related disorders, such as oxidative liver damage and inflammation diseases.

Catabolism of methyl ter-butyl ether (MTBE): characterization of the enzymes of Mycobacterium austroafricanum IFP 2012 involved in MTBE degradation; Catabolisme du methyl tert-butyl ether (MTBE): caracterisation des enzymes impliquees dans la degradation du MTBE chez Mycobacterium austroafricanum IFP 2012

Energy Technology Data Exchange (ETDEWEB)

Lopes Ferreira, N

2005-11-15

Methyl tert-butyl ether (MTBE) is added to gasoline to meet the octane index requirement. its solubility in water and its poor biodegradability made the use of MTBE a great environmental concern, particularly regarding aquifers. We previously isolated M austroafricanum IFP 2012 able to use MTBE as a sole source of carbon and energy and the MTBE pathway was partially characterized. In the present study, which aimed at isolating the genes involved in MTBE biodegradation in order to use them for estimation of MTBE biodegradation capacities in contaminated environment, we isolated a new M. austroafricanum strain, IFP 2015. A new degradation intermediate, the 2-methyl 1,2-propane-diol (2-M1,2-PD), the product of tert-butanol (TBA) oxidation, was identified. We also determined the enzymes induced during growth of M. austroafricanum IFP 2012 on MTBF. Then, using the tools of protein analysis and of molecular biology, we isolated and cloned the mpd genes cluster in the plasmid pCL4D. Heterologous expression of the recombinant plasmid in M smegmatis tmc2 155, showed the involvement of an 2-M1,2-PD dehydrogenase (MpdB) and a hydroxy-iso-butyr-aldehyde dehydrogenase (MpdC), encoded by mpdB and mpdC, respectively. Both enzymes were responsible for the conversion of 2-M 1,2-PD to hydroxy-isobutyric acid (HIBA). A further survey of different M austroafricanum strains, including IFP 2012, IFP 2015 and JOBS (ex-M vaccae) showed the link between the ability to grow on C{sub 2} to C{sub 16} n-alkanes and the MTBE and TBA degradation capacities. The alkB gene was partially sequenced in all these strains. Expression of alkB was demonstrated in M. austroafricanum IFP 2012 after growth on propane, hexane, hexadecane and TBA. Finally, we identified 2-propanol as the intermediate of HIBA degradation. The gene encoding the 2-propanol:p-N,N'-dimethyl-4-nitroso-aniline (NDMA) oxidoreductase was detected M austroafricanum IFP 2012. (author)

Catabolism of methyl ter-butyl ether (MTBE): characterization of the enzymes of Mycobacterium austroafricanum IFP 2012 involved in MTBE degradation; Catabolisme du methyl tert-butyl ether (MTBE): caracterisation des enzymes impliquees dans la degradation du MTBE chez Mycobacterium austroafricanum IFP 2012

Energy Technology Data Exchange (ETDEWEB)

Lopes Ferreira, N.

2005-11-15

Methyl tert-butyl ether (MTBE) is added to gasoline to meet the octane index requirement. its solubility in water and its poor biodegradability made the use of MTBE a great environmental concern, particularly regarding aquifers. We previously isolated M austroafricanum IFP 2012 able to use MTBE as a sole source of carbon and energy and the MTBE pathway was partially characterized. In the present study, which aimed at isolating the genes involved in MTBE biodegradation in order to use them for estimation of MTBE biodegradation capacities in contaminated environment, we isolated a new M. austroafricanum strain, IFP 2015. A new degradation intermediate, the 2-methyl 1,2-propane-diol (2-M1,2-PD), the product of tert-butanol (TBA) oxidation, was identified. We also determined the enzymes induced during growth of M. austroafricanum IFP 2012 on MTBF. Then, using the tools of protein analysis and of molecular biology, we isolated and cloned the mpd genes cluster in the plasmid pCL4D. Heterologous expression of the recombinant plasmid in M smegmatis tmc2 155, showed the involvement of an 2-M1,2-PD dehydrogenase (MpdB) and a hydroxy-iso-butyr-aldehyde dehydrogenase (MpdC), encoded by mpdB and mpdC, respectively. Both enzymes were responsible for the conversion of 2-M 1,2-PD to hydroxy-isobutyric acid (HIBA). A further survey of different M austroafricanum strains, including IFP 2012, IFP 2015 and JOBS (ex-M vaccae) showed the link between the ability to grow on C{sub 2} to C{sub 16} n-alkanes and the MTBE and TBA degradation capacities. The alkB gene was partially sequenced in all these strains. Expression of alkB was demonstrated in M. austroafricanum IFP 2012 after growth on propane, hexane, hexadecane and TBA. Finally, we identified 2-propanol as the intermediate of HIBA degradation. The gene encoding the 2-propanol:p-N,N'-dimethyl-4-nitroso-aniline (NDMA) oxidoreductase was detected M austroafricanum IFP 2012. (author)

Radiation induced peroxidation of polyunsaturated fatty acids: recent results on formation of hydroperoxides

Energy Technology Data Exchange (ETDEWEB)

Hauville, C.; Remita, S. [Lab. de Chimie Physique, Univ. Rene Descartes, Paris (France); Therond, P. [Lab. de Biochimie, Hopital de Bicetre, Le Kremlin Bicetre (France); Jore, D.; Gardes-Albert, M. [Lab. de Chimie Physique, Univ. Rene Descartes, Paris (France)

2001-02-01

Aqueous solutions of linoleic acid were irradiated in air with {gamma}-rays of {sup 137}Cs. High pressure liquid chromatography (HPLC) was been used to separate and measure the production of hydroperoxides. The results obtained after reverse phase chromatography, associated with a microperoxydase for hydroperoxide detection, indicate the presence of two different hydroperoxides. One type of hydroperoxide was the major product obtained when the initial linoleic concentrations were below the critical micellar concentration (2 mM), and the second type was produced when the concentrations were above 2 mM. A further separation carried out on the second hydroperoxide by direct phase HPLC showed that it contains three compounds, mainly HPODE 9 and 13. (author)

Radiation induced peroxidation of polyunsaturated fatty acids: recent results on formation of hydroperoxides

International Nuclear Information System (INIS)

Hauville, C.; Remita, S.; Therond, P.; Jore, D.; Gardes-Albert, M.

2001-01-01

Aqueous solutions of linoleic acid were irradiated in air with γ-rays of 137 Cs. High pressure liquid chromatography (HPLC) was been used to separate and measure the production of hydroperoxides. The results obtained after reverse phase chromatography, associated with a microperoxydase for hydroperoxide detection, indicate the presence of two different hydroperoxides. One type of hydroperoxide was the major product obtained when the initial linoleic concentrations were below the critical micellar concentration (2 mM), and the second type was produced when the concentrations were above 2 mM. A further separation carried out on the second hydroperoxide by direct phase HPLC showed that it contains three compounds, mainly HPODE 9 and 13. (author)

Effects of intraperitoneal administration of the GABAB receptor positive allosteric modulator 2,6-di tert-butyl-4-(2-hydroxy-2,2-dimethyl-propyl)-phenol (CGP7930) on food intake in non-deprived rats.

Science.gov (United States)

Ebenezer, Ivor S

2012-09-05

γ-Aminobutyric acid-(B) (GABA(B)) receptor positive allosteric modulators (PAMs) act on an allosteric site on the GABA(B) receptor to potentiate the effects of GABA and GABA(B) receptor agonists. It has previously been demonstrated that the GABA(B) receptor agonist baclofen increases food intake in non-deprived rats. The aim of this study was to investigate whether the GABA(B) receptor PAM 2,6-di tert-butyl-4-(2-hydroxy-2,2-dimethyl-propyl)-phenol (CGP7930) would (i) increase food intake, and (ii) potentiate the hyperphagic effects of baclofen in rats. In Experiment 1, the effects of intraperitoneal (i.p.) administration of CGP7930 (1, 6 and 12 mg/kg) was investigated on food intake in non-deprived male Wistar rats. The 12 mg/kg dose of CGP7930 significantly increased cumulative food intake 30, 60 and 120 min (PGABA and GABA(B) receptor agonists by allosteric modulation of the GABA(B) receptor. Copyright © 2012 Elsevier B.V. All rights reserved.

Butylated caffeic acid: An efficient novel antioxidant; Ácido cafeico butilado: un nuevo y eficaz antioxidante.

Energy Technology Data Exchange (ETDEWEB)

Shi, G.; Liao, X.; Olajide, T.M.; Liu, J.; Jiang, X.; Weng, X.

2017-07-01

A novel antioxidant, butylated caffeic acid (BCA) was rationally designed by adding a tert-butyl group to caffeic acid, which was synthesized at a high yield (36.2%) from 2-methoxy-4-methylphenol (1) by a four-step reaction including Friedel-Crafts alkylation, bromine oxidation, ether bond hydrolysis and Knoevenagel condensation. Its antioxidant capacity was much stronger than common commercial antioxidant tert-butyl hydroquinone (TBHQ) and its mother compound, caffeic acid, in both rancimat and deep frying tests. When investigated via the DPPH method, the antioxidant capacity of BCA was almost equal to TBHQ, but lower than caffeic acid. BCA could be a potentially strong antioxidant, especially for food processing at high temperatures such as deep frying and baking. [Spanish] Se diseñó razonadamente un nuevo antioxidante, el ácido cafeico butilado (BCA) mediante la adición de un grupo terc-butilo al ácido cafeico, que se sintetizó con un alto rendimiento (36,2%) a partir de 2-metoxi-4-metilfenol, reacción de Friedel-Crafts, oxidación de bromo, hidrólisis del enlace éter y condensación de Knoevenagel. Su capacidad antioxidante fué mucho más fuerte que la del antioxidante comercial mas común el terc-butil hidroquinona (TBHQ) y la de su compuesto madre el ácido cafeico, tanto en rancimat como en pruebas de fritura. Cuando se investigó mediante el método DPPH, la capacidad antioxidante de BCA fue casi igual a TBHQ, pero menor que la del ácido cafeico. BCA podría ser un fuerte antioxidante potencial, especialmente para el procesamiento de alimentos a alta temperatura, tales como freír y hornear.

Bidentate urea derivatives of p-tert-butyldihomooxacalix[4]arene: neutral receptors for anion complexation.

Science.gov (United States)

Marcos, Paula M; Teixeira, Filipa A; Segurado, Manuel A P; Ascenso, José R; Bernardino, Raul J; Michel, Sylvia; Hubscher-Bruder, Véronique

2014-01-17

Three new bidentate ureidodihomooxacalix[4]arene derivatives (phenyl 5a, n-propyl 5b, and tert-butyl 5c) were synthesized in four steps from the parent compound p-tert-butyldihomooxacalix[4]arene and obtained in the cone conformation, as shown by NMR studies. The binding ability of these neutral receptors toward spherical, linear, trigonal planar, and tetrahedrical anions was assessed by (1)H NMR and UV-vis titrations. The structures and complexation energies of some complexes were also studied by DFT methods. The data showed that the association constants are strongly dependent on the nature of the substituent (aryl/alkyl) at the urea moiety. In general, for all the receptors, the association constants decrease with decrease of anion basicity. Ph-urea 5a is the best anion receptor, showing the strongest complexation for F(-) (log K(assoc) = 3.10 in CDCl3) and also high binding affinity for the carboxylates AcO(-) and BzO(-). Similar results were obtained by UV-vis studies and were also corroborated by DFT calculations.

1H chemically induced dynamic nuclear polarization in the photodecomposition of uranyl carboxylates

International Nuclear Information System (INIS)

Rykov, S.V.; Khudyakov, I.V.; Skakovsky, E.D.; Burrows, H.D.; Formosinho, S.J.; Miguel, M. da G.M.

1991-01-01

Chemically induced dynamic nuclear polarization ( 1 H CIDNP) has been observed during photolysis of uranyl salts of pivalic, propionic, and acetic acids in D 2 O solution, [ 2 H 6 ]acetone, [ 2 H 4 ]methanol, or in some other solvent. The multiplet polarization of isobutene and isobutane protons has been found under photolysis of deoxygenated pivalate solution. The polarized compounds are formed in the triplet pairs of tert-butyl free radicals. 1 H Emission of the tert-butylperoxyl group and emission of 1 H from isobutene have been recorded under photolysis of air-saturated pivalate solutions. The CIDNP of butane protons stays as a multiplet. Such changes in the presence of air/oxygen have arisen apparently because of the formation of tert-butylperoxyl free radical and its reaction with tert-butyl radical products, i.e. hydroperoxide (peroxide) and isobutene. Isobutene probably forms a complex with molecular oxygen which has a very short proton relaxation time. During the photolysis of uranyl pivalate in the presence of p-benzoquinone (5 x 10 -2 -0.1 mol dm -3 ) we have not observed any CIDNP, whereas under p-benzoquinone concentrations of 10 -3 -10 -2 mol dm -3 the CIDNP from both hydroquinone and p-benzoquinone has been followed. Photolysis of uranyl propionate has led to CIDNP from butane protons. An emission from methyl group protons of a compound with an ethylperoxyl fragment in the presence of air/oxygen has been observed. The same polarization picture has arisen under interaction of photoexcited uranyl with propionic acid. During the photolysis of uranyl acetate at relatively low concentrations (10 -2 mol dm -3 ) a CIDNP very similar to that registered for uranyl propionate was recorded. The ethyl fragment is probably obtained in reactions for two methyl radicals formed from acetate with the parent uranyl acetate, namely hydrogen-atom abstraction and addition reactions. (author)

Anionic polymerization of acrylates. XII. Polymerization of methyl methacrylate and tert-butyl acrylate initiated with alkyllithiums or methyl 2-lithioisobutyrate in the presence of lithium tert-butoxide

Czech Academy of Sciences Publication Activity Database

Vlček, Petr; Otoupalová, Jaroslava; Janata, Miroslav; Látalová, Petra; Masař, Bohumil; Toman, Luděk

2002-01-01

Roč. 43, č. 25 (2002), s. 7179-7184 ISSN 0032-3861 R&D Projects: GA ČR GA203/01/0513; GA MŠk OC P1.10 Institutional research plan: CEZ:AV0Z4050913 Keywords : ligated anionic polymerization * (meth)acrylates * lithium tert-butoxide Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.838, year: 2002

Method for producing redox shuttles

Science.gov (United States)

Pupek, Krzysztof Z.; Dzwiniel, Trevor L.; Krumdick, Gregory K.

2015-03-03

A single step method for producing a redox shuttle having the formula 2,5-di-tert-butyl-1,4-phenylene tetraethyl bis(phosphate) is provided, the method comprising phosphorylating tert butyl hydroquinone with a phosphate-containing reagent. Also provided is method for producing 2,5-di-tert-butyl-1,4-phenylene tetraethyl bis(phosphate), the method comprising solubilizing tert-butyl hydroquinone and tetrabutylammonium bromide with methyltetrahydrofuran to create a mixture; heating the mixture while adding base to the mixture in an amount to turn the mixture orange; and adding diethyl chlorophosphate to the orange mixture in an amount to phosphorylate the hydroquinone.

Fluctuating micro-heterogeneity in water–tert-butyl alcohol mixtures and lambda-type divergence of the mean cluster size with phase transition-like multiple anomalies

International Nuclear Information System (INIS)

Banerjee, Saikat; Furtado, Jonathan; Bagchi, Biman

2014-01-01

Water–tert-butyl alcohol (TBA) binary mixture exhibits a large number of thermodynamic and dynamic anomalies. These anomalies are observed at surprisingly low TBA mole fraction, with x TBA ≈ 0.03–0.07. We demonstrate here that the origin of the anomalies lies in the local structural changes that occur due to self-aggregation of TBA molecules. We observe a percolation transition of the TBA molecules at x TBA ≈ 0.05. We note that “islands” of TBA clusters form even below this mole fraction, while a large spanning cluster emerges above that mole fraction. At this percolation threshold, we observe a lambda-type divergence in the fluctuation of the size of the largest TBA cluster, reminiscent of a critical point. Alongside, the structure of water is also perturbed, albeit weakly, by the aggregation of TBA molecules. There is a monotonic decrease in the tetrahedral order parameter of water, while the dipole moment correlation shows a weak nonlinearity. Interestingly, water molecules themselves exhibit a reverse percolation transition at higher TBA concentration, x TBA ≈ 0.45, where large spanning water clusters now break-up into small clusters. This is accompanied by significant divergence of the fluctuations in the size of largest water cluster. This second transition gives rise to another set of anomalies around. Both the percolation transitions can be regarded as manifestations of Janus effect at small molecular level

Photoinduced azidohydroperoxidation of myrtenyl hydroperoxide with semiconductor particles and lucigenin as PET-catalysts.

Science.gov (United States)

Griesbeck, Axel G; Reckenthäler, Melissa; Uhlig, Johannes

2010-06-01

The allylic hydroperoxide 2 (myrtenyl hydroperoxide), available from singlet oxygen photooxygenation of beta-pinene (1), is converted into the azido bis-hydroperoxide 3 by an electron-transfer induced azidyl radical formation and trapping of the initial tertiary carbon radical by triplet oxygen. The azido bis-hydroperoxide 3 is reduced to the azido 1,2-diol 4 or the amino diol 5, respectively. Beside classical fluorescent PET sensitizers such as rhodamines, also nanosized semiconductor particles as well as lucigenin were applied as catalysts. The electron transfer rate of azide oxidation was determined for lucigenin by fluorescence quenching analysis.

Development and application of a rat PBPK model to elucidate kidney and liver effects induced by ETBE and tert-butanol

International Nuclear Information System (INIS)

Salazar, Keith D.; Brinkerhoff, Christopher J.; Lee, Janice S.; Chiu, Weihsueh A.

2015-01-01

Subchronic and chronic studies in rats of the gasoline oxygenates ethyl tert-butyl ether (ETBE) and tert-butanol (TBA) report similar noncancer kidney and liver effects but differing results with respect to kidney and liver tumors. Because TBA is a major metabolite of ETBE, it is possible that TBA is the active toxic moiety in all these studies, with reported differences due simply to differences in the internal dose. To test this hypothesis, a physiologically-based pharmacokinetic (PBPK) model was developed for ETBE and TBA to calculate internal dosimetrics of TBA following either TBA or ETBE exposure. This model, based on earlier PBPK models of methyl tert-butyl ether (MTBE), was used to evaluate whether kidney and liver effects are consistent across routes of exposure, as well as between ETBE and TBA studies, on the basis of estimated internal dose. The results demonstrate that noncancer kidney effects, including kidney weight changes, urothelial hyperplasia, and chronic progressive nephropathy (CPN), yielded consistent dose–response relationships across routes of exposure and across ETBE and TBA studies using TBA blood concentration as the dose metric. Relative liver weights were also consistent across studies on the basis of TBA metabolism, which is proportional to TBA liver concentrations. However, kidney and liver tumors were not consistent using any dose metric. These results support the hypothesis that TBA mediates the noncancer kidney and liver effects following ETBE administration; however, additional factors besides internal dose are necessary to explain the induction of liver and kidney tumors. - Highlights: • We model two metabolically-related fuel oxygenates to address toxicity data gaps. • Kidney and liver effects are compared on an internal dose basis. • Noncancer kidney effects are consistent using TBA blood concentration. • Liver weight changes are consistent using TBA metabolic rate. • Kidney and liver tumors are not consistent using

Development and application of a rat PBPK model to elucidate kidney and liver effects induced by ETBE and tert-butanol

Energy Technology Data Exchange (ETDEWEB)

Salazar, Keith D., E-mail: Salazar.keith@epa.gov [Toxicity Pathways Branch, IRIS Division, NCEA, ORD, US EPA, Washington, DC 20460 (United States); Brinkerhoff, Christopher J., E-mail: Brinkerhoff.Chris@epa.gov [Risk Assessment Division, OPPT, OCSPP, US EPA, Washington, DC 20460 (United States); Lee, Janice S., E-mail: Lee.JaniceS@epa.gov [Toxicity Pathways Branch, IRIS Division, NCEA, ORD, US EPA, Washington, DC 20460 (United States); Chiu, Weihsueh A., E-mail: wchiu@cvm.tamu.edu [Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A& M University, College Station, TX 77843 (United States)

2015-11-01

Subchronic and chronic studies in rats of the gasoline oxygenates ethyl tert-butyl ether (ETBE) and tert-butanol (TBA) report similar noncancer kidney and liver effects but differing results with respect to kidney and liver tumors. Because TBA is a major metabolite of ETBE, it is possible that TBA is the active toxic moiety in all these studies, with reported differences due simply to differences in the internal dose. To test this hypothesis, a physiologically-based pharmacokinetic (PBPK) model was developed for ETBE and TBA to calculate internal dosimetrics of TBA following either TBA or ETBE exposure. This model, based on earlier PBPK models of methyl tert-butyl ether (MTBE), was used to evaluate whether kidney and liver effects are consistent across routes of exposure, as well as between ETBE and TBA studies, on the basis of estimated internal dose. The results demonstrate that noncancer kidney effects, including kidney weight changes, urothelial hyperplasia, and chronic progressive nephropathy (CPN), yielded consistent dose–response relationships across routes of exposure and across ETBE and TBA studies using TBA blood concentration as the dose metric. Relative liver weights were also consistent across studies on the basis of TBA metabolism, which is proportional to TBA liver concentrations. However, kidney and liver tumors were not consistent using any dose metric. These results support the hypothesis that TBA mediates the noncancer kidney and liver effects following ETBE administration; however, additional factors besides internal dose are necessary to explain the induction of liver and kidney tumors. - Highlights: • We model two metabolically-related fuel oxygenates to address toxicity data gaps. • Kidney and liver effects are compared on an internal dose basis. • Noncancer kidney effects are consistent using TBA blood concentration. • Liver weight changes are consistent using TBA metabolic rate. • Kidney and liver tumors are not consistent using

Analysis of Hydroperoxides in solid Polyethylene by NMR and EPR Spectroscopy

International Nuclear Information System (INIS)

Assink, Roger A.; Celina, Mathias C.; Dunbar, Timothy D.; Alam, Todd M.; Clough, Roger Lee; Gillen, Kenneth T.

2000-01-01

The authors have shown that the hydroperoxide species in γ-irradiated 13 C-polyethylene can be directly observed by 13 C MAS NMR spectroscopy. The experiment was performed without the need for special sample preparation such as chemical derivatization or dissolution. Annealing experiments were employed to study the thermal decomposition of the hydroperoxide species and to measure an activation energy of 98 kJ/mol. EPR spectroscopy suggests that residual polyenyl and alkylperoxy radicals are predominantly trapped in interracial or crystalline regions, while the peroxy radicals observed after UV-photolysis of hydroperoxides are in amorphous regions

Biochemical Abnormalities in Batten's Syndrome

DEFF Research Database (Denmark)

Clausen, Jytte Lene; Nielsen, Gunnar Gissel; Jensen, Gunde Egeskov

1978-01-01

The present data indicate that a group of ten patients with Batten's syndrome showed reduced activity of erythrocyte glutathione (GSH) peroxidase (Px) (glutathione: H2O2 oxidoreductase, EC 1.1.1.9.) using H2O2 as peroxide donor. Assay of erythrocyte GSHPx using H2O2, cumene hydroperoxide and t......-butyl hydroperoxide as donors also makes it possible biochemically to divide Batten's syndrome into two types: (1) one type with decreased values when H2O2 and cumene hydroperoxide are used, and (2) one type with increased values when t-butyl hydroperoxide is used. Furthermore an increased content of palmitic, oleic...

Analysis of Hydroperoxides in Solid Polyethylene by MAS (13)C NMR and EPR

International Nuclear Information System (INIS)

ASSINK, ROGER A.; CELINA, MATHIAS C.; DUNBAR, TIMOTHY D.; ALAM, TODD M.; CLOUGH, ROGER LEE; GILLEN, KENNETH T.

1999-01-01

13 C-enriched polyethylene was subjected to γ-irradiation in the presence of air at 25 and 80 C for total doses ranging from 71 to 355 kGy. Significant quantities of hydroperoxides were detected in the 25 C irradiated sample by 13 C magic angle spinning NMR spectroscopy. This method of detection was performed on the solid polymer and required no chemical derivatization or addition of solvent. The chemical stability and subsequent products of the hydroperoxide species were studied by annealing the irradiated samples in air at temperatures ranging from 22 to 110 C. A time-temperature superposition analysis provided an activation energy of 108 kJ/mol for the hydroperoxide decomposition process. The primary products of hydroperoxide decomposition were ketones and secondary alcohols with lesser amounts of acids and esters. EPR measurements suggest that the reactive hydroperoxide species reside in the amorphous phase of polyethylene, consistent with degradation occurring in the amorphous phase

General regularities of olefin epoxidation by hydroperoxide catalyzed by V, W and Ti compounds

International Nuclear Information System (INIS)

Sapunov, V.N.; Sharykin, V.G.; Logvinov, A.S.; Litvintsev, I.Yu.; Lebedev, N.N.

1983-01-01

The kinetic analysis of cyclohexane epoxidation by ethylbenzene hydroperoxide when catalyzed by titanium- and tungsten cyclohexandiolates has shown that the reaction follows the main regularities of hydroperoxide epoxidation previously established for catalysis by molybdenum- and vanadiUm compounds. The catalyst activity varies depending on the metal nature and forms the following series: Mo>V>W>Ti, which agrees with their π-acceptor capacity. During the cyclohexane epoxidation on all catalysts the hydroperoxide activities vary according to the following series: ethylbenzene hydroperoxide>cumene>tertiarybutyl>tertiaryamyl. Correlation relationships between the olefine structure, characterized by th constants, and the reactivity of olefines are foUnd. The reaction sensitivity during catalysis by WV, and Ti cyclohexandiolates is -1.2, -1.0- and -1.3, respectively. The mechanism of hydroperoxide epoxidation of olefine is discussed

Bis({tris[2-(3,5-di-tert-butyl-2-oxidobenzylideneaminoethyl]amine}cerium(III diethyl ether solvate

Directory of Open Access Journals (Sweden)

Peter Dröse

2010-11-01

Full Text Available The title compound, 2[Ce(C51H75N4O3]·C4H10O, was obtained in high yield (92% by reduction of (TRENDSALCeIVCl [TRENDSAL is N,N′,N′′-tris(3,5-di-tert-butylsalicylidenatoaminotriethylamine] with potassium in THF. The bulky tripodal TRENDSAL ligand effectively encapsulates the central CeIII cation with a Ce—N(imine distance of 2.860 (2 Å and an average C—N(amine distance of 2.619 Å within a distorted monocapped octahedral coordination.

Formation of zinc-peptide spherical microparticles during lyophilization from tert-butyl alcohol/water co-solvent system.

Science.gov (United States)

Qian, Feng; Ni, Nina; Chen, Jia-Wen; Desikan, Sridhar; Naringrekar, Vijay; Hussain, Munir A; Barbour, Nancy P; Smith, Ronald L

2008-12-01

To understand the mechanism of spherical microparticle formation during lyophilizing a tert-Butyl alcohol (TBA)/water solution of a zinc peptide adduct. A small peptide, PC-1, as well as zinc PC-1 at (3:2) and (3:1) ratios, were dissolved in 44% (wt.%) of TBA/water, gradually frozen to -50 degrees C over 2 h ("typical freezing step"), annealed at -20 degrees C for 6 h ("annealing step"), and subsequently lyophilized with primary and secondary drying. Zinc peptide (3:1) lyophile was also prepared with quench cooling instead of the typical freezing step, or without the annealing step. Other TBA concentrations, i.e., 25%, 35%, 54% and 65%, were used to make the zinc peptide (3:1) adduct lyophile with the typical freezing and annealing steps. The obtained lyophile was analyzed by Scanning Electron Microscopy (SEM). The zinc peptide solutions in TBA/water were analyzed by Differential Scanning Calorimeter (DSC). The surface tension of the TBA/water co-solvent system was measured by a pendant drop shape method. With typical freezing and annealing steps, the free peptide lyophile showed porous network-like structure that is commonly seen in lyophilized products. However, with increasing the zinc to peptide ratio, uniform particles were gradually evolved. Zinc peptide (3:1) adduct lyophiles obtained from 25%, 35% and 44% TBA exhibit a distinctive morphology of uniform and spherical microparticles with diameters of approximately 3-4 microm, and the spherical zinc peptide particles are more predominant when the TBA level approaches 20%. Adopting quench cooling in the lyophilization cycle leads to irregular shape fine powders, and eliminating the annealing step causes rough particles surface. When TBA concentration increases above 54%, the lyophiles demonstrate primarily irregular shape particles. A proposed mechanism of spherical particle formation of the 3:1 zinc peptide encompasses the freezing of a TBA/water solution (20-70% TBA) causing the formation of a TBA hydrate

Detection Identification and Quantification of Keto-Hydroperoxides in Low-Temperature Oxidation.

Energy Technology Data Exchange (ETDEWEB)

Hansen, Nils; Moshammer, Kai; Jasper, Ahren W.

2017-07-01

Keto-hydroperoxides are reactive partially oxidized intermediates that play a central role in chain-branching reactions during the low-temperature oxidation of hydrocarbons. In this Perspective, we outline how these short lived species can be detected, identified, and quantified using integrated experimental and theoretical approaches. The procedures are based on direct molecular-beam sampling from reactive environments, followed by mass spectrometry with single-photon ionization, identification of fragmentation patterns, and theoretical calculations of ionization thresholds, fragment appearance energies, and photoionization cross sections. Using the oxidation of neo-pentane and tetrahydrofuran as examples, the individual steps of the experimental approaches are described in depth together with a detailed description of the theoretical efforts. For neo-pentane, the experimental data are consistent with the calculated ionization and fragment appearance energies of the keto-hydroperoxide, thus adding confidence to the analysis routines and the employed levels of theory. For tetrahydrofuran, multiple keto-hydroperoxide isomers are possible due to the presence of nonequivalent O₂ addition sites. Despite this additional complexity, the experimental data allow for the identification of two to four keto-hydroperoxides. Mole fraction profiles of the keto-hydroperoxides, which are quantified using calculated photoionization cross sections, are provided together with estimated uncertainties as function of the temperature of the reactive mixture and can serve as validation targets for chemically detailed mechanisms.

Alfalfa contains substantial 9-hydroperoxide lyase activity and a 3Z:2E-enal isomerase

NARCIS (Netherlands)

Vliegenthart, J.F.G.; Noordermeer, M.A.; Veldink, G.A.

1999-01-01

Fatty acid hydroperoxides formed by lipoxygenase can be cleaved by hydroperoxide lyase resulting in the formation of short-chain aldehydes and omega-oxo acids. Plant hydroperoxide lyases use 13- or 9-hydroperoxy linoleic and linolenic acid as substrates. Alfalfa (Medicago sativa L.) has been

Solution processable 2-(trityloxy)ethyl and tert-butyl group containing amorphous molecular glasses of pyranylidene derivatives with light-emitting and amplified spontaneous emission properties

Science.gov (United States)

Zarins, Elmars; Vembris, Aivars; Misina, Elina; Narels, Martins; Grzibovskis, Raitis; Kokars, Valdis

2015-11-01

Small organic molecules with incorporated 4H-pyran-4-ylidene (pyranylidene) fragment as the π-conjugation system which bonds the electron acceptor fragment (A) with electron donor part (D) in the molecule - also well known as derivatives of 4-(dicyano-methylene)-2-methyl-6-[p-(dimethylamino)styryl]-4H-pyran (DCM) laser dye-have attracted considerable attention of scientists as potential new generation materials for organic photonics and molecular electronics due to their low-cost fabrication possibility, flexibility and low-weight. Six glassy derivatives of 4H-pyran-4-ylidene (pyranylidene) with attached bulky 2-(trityloxy)ethyl and tert-butyl groups are described in this report. Almost all of the synthesized compounds form good optical quality transparent amorphous films from volatile organic solvents and could be obtained in good yields up to 75%. Their light emission in solution and thin solid films is in the range of 600-700 nm, they are thermally stable and show glass transition in the range of 108-158 °C. The amplified spontaneous emission threshold values of the neat films of the glassy pyranylidene derivatives vary from 155 to 450 μJ/cm2 and their HOMO and LUMO energy levels are between of those of tris(8-hydroxy quinolinato) aluminum (Alq3). The photoluminescence quantum yields of the glassy compounds are in the range from 1% to about 7.7% and their electroluminescence properties have been investigated. Therefore, glassy pyranylidene derivatives could be a very potential low-cost solution processable materials for Alq3 hosted light-amplification and light-emitting application studies.

Synthesis, characterization, and properties of peroxo-based oxygen-rich compounds for potential use as greener high energy density materials

Science.gov (United States)

Gamage, Nipuni-Dhanesha Horadugoda

One main aspect of high energy density material (HEDM) design is to obtain greener alternatives for HEDMs that produce toxic byproducts. Primary explosives lead azide, lead styphnate, and mercury fulminate contain heavy metals that cause heavy metal poisoning. Leaching of the widely used tertiary explosive NH4ClO4 into groundwater has resulted in human exposure to ClO4-- ions, which cause disruptions of thyroid related metabolic pathways and even thyroid cancer. Many research efforts to find replacements have gained little success. Thus, there is a need for greener HEDMs. Peroxo-based oxygen-rich compounds are proposed as a potential new class of greener HEDMs due to the evolution of CO2 and/or CO, H2O, and O 2 as the main decomposition products. Currently, triacetone triperoxide (TATP), diacetone diperoxide (DADP), hexamethylene triperoxide diamine (HMTD), and methyl ethyl ketone peroxide (MEKP) are the only well-studied highly energetic peroxides. However, due to their high impact and friction sensitivities, low thermal stabilities, and low detonation velocities they have not found any civil or military HEDM applications. In this dissertation research, we have synthesized and fully characterized four categories of peroxo-based compounds: tert-butyl peroxides, tert-butyl peroxy esters, hydroperoxides, and peroxy acids to perform a systematic study of their sensitivities and the energetic properties for potential use as greener HEDMs. tert-Butyl peroxides were not sensitive to impact, friction, or electrostatic spark. Hence, tert-butyl peroxides can be described as fairly safe peroxo-based compounds to handle. tert-Butyl peroxy esters were all surprisingly energetic (4896--6003 m/s), despite the low oxygen and nitrogen contents. Aromatic tert -butyl peroxy esters were much lower in impact and friction sensitivities with respect to the known peroxo-based explosives. These are among the first low sensitivity peroxo-based compounds that can be categorized as secondary

Measurement of critical temperatures and critical pressures for binary mixtures of methyl tert-butyl ether (MTBE) + alcohol and MTBE + alkane

International Nuclear Information System (INIS)

Han, Kewei; Xia, Shuqian; Ma, Peisheng; Yan, Fangyou; Liu, Tao

2013-01-01

Highlights: • The critical properties of seven binary mixtures related to gasoline were measured. • The critical properties of the five systems containing MTBE were reported for the first time. • Binary interaction parameters were fitted by experimental data using PR EOS with Wong–Sandler mixing rule. • Redlich–Kister equation was used to correlate the experimental data. -- Abstract: A set of high-pressure view apparatus was designed for determining the critical properties of chemicals. In order to check the reliability of the apparatus, the critical temperatures (T c ) and critical pressures (P c ) of pure n-heptane, cyclohexane, methanol, ethanol, 1-propanol, methyl tert-butyl ether (MTBE), and binary mixture n-hexane + ethanol were measured. The experimental data were in good agreement with the literature data, which proves the reliability of the apparatus used in the work. The critical temperatures and critical pressures of five binary mixtures containing gasoline additive (MTBE + n-heptane, MTBE + cyclohexane, MTBE + methanol, MTBE + ethanol, MTBE + 1-propanol) were measured using the high-pressure view cell with visual observation. The critical temperatures and critical pressures for the five binary mixtures were all reported for the first time. In addition, the critical temperatures and critical pressures of the binary mixture n-heptane + cyclohexane (two of main components in gasoline) were also measured. All the critical lines for the mixtures studied are continuous which connect the critical points of the two pure components, indicating their phase diagrams belong to type I proposed by Scott and van Konynenburg. The critical points of these systems were calculated by the Peng–Robinson equation of state with the Wong–Sandler mixing rule. This model could calculate the critical properties of the mixtures well with the binary interaction parameter k ij obtained by fitting the experimental critical data. And the experimental data were all

Constitutive expression of tert in thymocytes leads to increased incidence and dissemination of T-cell lymphoma in Lck-Tert mice.

Science.gov (United States)

Canela, Andrés; Martín-Caballero, Juan; Flores, Juana M; Blasco, María A

2004-05-01

Here we describe a new mouse model with constitutive expression of the catalytic subunit of telomerase (Tert) targeted to thymocytes and peripheral T cells (Lck-Tert mice). Two independent Lck-Tert mouse lines showed higher incidences of spontaneous T-cell lymphoma than the corresponding age-matched wild-type controls, indicating that constitutive expression of Tert promotes lymphoma. Interestingly, T-cell lymphomas in Lck-Tert mice were more disseminated than those in wild-type controls and affected both lymphoid and nonlymphoid tissues, while nonlymphoid tissues were never affected with lymphoma in age-matched wild-type controls. Importantly, these roles of Tert constitutive expression in promoting tumor progression and dissemination were independent of the role of telomerase in telomere length maintenance, since telomere length distributions on a single-cell basis were identical in Lck-Tert and wild-type thymocytes. Finally, Tert constitutive expression did not interfere with telomere capping in Lck-Tert primary thymocytes, although it resulted in greater chromosomal instability upon gamma irradiation in Lck-Tert primary lymphocytes than in controls, suggesting that Tert overexpression may interfere with the cellular response to DNA damage.

Selective oxidation of benzyl alcohol with tert-butylhydroperoxide ...

Indian Academy of Sciences (India)

the solvent and in this case, acetonitrile gives the best conversion results. The kinetic of ... Experimental. 2.1 Materials ... Subsequently, the products were filtered, washed thoroughly ..... mesh; benzyl alcohol 30 mmol; TBHP 30 mmol; 15 ml ace- tonitrile ... vent was changed for each run while the other condi- tions, (0.2 g of ...

Hydroperoxide-dependent oxygenation of polycyclic aromatic hydrocarbons and their metabolites

International Nuclear Information System (INIS)

Marnett, L.J.

1985-01-01

Fatty acid hydroperoxides in the presence of heme complexes and heme proteins oxidize benzo(a)pyrene and 7,8-dihydroxy-7, 8-dihydrobenzo(a)pyrene to quinones and diol epoxides, respectively. The oxidizing agent is a peroxyl radical derived from the fatty acid hydroperoxide but not a higher oxidation state of a mammalian peroxidase. The stereochemistry of (+-)-BP-dihydrodiol epoxidation is distinct from that catalyzed by mixed-function oxidases, which provides a convenient method for discriminating the contributions of the two systems to BP-7,8-dihydrodiol metabolism in cell homogenates, cell or organ culture. Using this method, epoxidation of BP-7,89-dihydroodiol has been detected during prostaglandin biosynthesis, lipid peroxidation, and xenobiotic oxygenation. Fatty acid hydroperoxide-dependent oxidation constitutes a novel pathway for metabolic activation of polycyclic hydrocarbons and other carcinogens which has widespread potential in vivo significance

Vibrational spectra and ab initio analysis of tert-butyl, trimethylsilyl, and trimethylgermyl derivatives of 3,3-dimethylcyclopropene IV. 3,3-Dimethyl-1,2-bis(trimethylgermyl)cyclopropene

Science.gov (United States)

Panchenko, Yu. N.; De Maré, G. R.; Abramenkov, A. V.; Baird, M. S.; Tverezovsky, V. V.; Nizovtsev, A. V.; Bolesov, I. G.

2003-06-01

The infrared (IR) and Raman spectra of 3,3-dimethyl-1,2-bis(trimethylgermyl)cyclopropene (I) were measured in the liquid phase. Total geometry optimisation was performed at the HF/6-31G* level. The HF/6-31G*//HF6-31G* quantum mechanical force field (QMFF) was calculated and used to determine the theoretical fundamental vibrational frequencies, their predicted IR intensities, Raman activities, and Raman depolarisation ratios. Using Pulay's scaling method and the theoretical molecular geometry, the QMFF of I was scaled by a set of scaling factors comprised of elements transferred from the sets used to correct the QMFF's of 3,3-dimethylbutene-1, and 1-methyl-, 1,2-dimethyl-, and 3,3-dimethylcyclopropene (17 scale factors for a 105-dimensional problem). This set of scale factors was used previously to correct the QMFF of 3,3-dimethyl-1,2-bis(tert-butyl)cyclopropene and 3,3-dimethyl-1,2-bis(trimethylsilyl)cyclopropene. The scaled QMFF obtained was used to solve the vibrational problem. Differential Raman cross-sections were calculated using the quantum mechanical values of the Raman activities. The appropriate theoretical spectrograms for the Raman and IR spectra of I were constructed. Assignments of the experimental vibrational spectra of I are given. They take into account the calculated potential energy distributions and the correlation between the estimations of the experimental IR and Raman intensities and Raman depolarisation ratios and the corresponding theoretical values calculated using the unscaled QMFF.

Formation of protein hydroperoxides in mouse myeloma cell line Sp2/0-Ag14

International Nuclear Information System (INIS)

Du, J.; Gebicki, J.

2000-01-01

Full text: Free radicals generated by normal cell metabolism or from environmental sources can cause damage to DNA, proteins and lipids-the important components of mammalian cells. As function molecules and cell constituent, the abundant and easily available nature of proteins make them the prime target of free radicals. Previous research in our lab have shown protein hydroperoxides in turn can react with other proteins, result in the lose of enzymatic function of the later, or crosslink with DNA, which may interfere gene transcription if not repaired. The formation of protein hydroperoxides in Sp2/0-Ag14 cells was induced by exposing them to peroxyl radical or gamma radiation. Cells were then washed and precipitated by tichloroacetic acid. Concentration of protein and lipid hydroperoxides were measured by FOX assay. No significant amount of lipid peroxides were detected. The effects of reducing agents dithiothreitol, glutathione, sodium borohydride identified the nature of protein hydroperoxides. The life time of cell protein hydroperoxides is about 2 hours

μ-Carbonato-κ(4) O,O':O',O''-bis-{[2'-(di-tert-butyl-phosphan-yl)biphenyl-2-yl-κ(2) P,C (1)]palladium(II)} dichloro-methane monosolvate.

Science.gov (United States)

Muller, Alfred; Holzapfel, Cedric W

2012-12-01

The title compound, [(μ2-CO3){Pd(P(t-C4H9)2(C12H8)}2]·CH2Cl2, the first CO3-bridged palladium dimer complex reported to date, was obtained while preparing the Pd(0) complex with (2-biphen-yl)P( (t) Bu)2. In the crystal, each palladium dimer is accompanied by a dichloro-methane solvent mol-ecule. Coordination of the carbonate and chelated phosphane ligands gives distorted square-planar environments at the Pd atoms. Important geometrical parameters include Pd-P(av.) = 2.2135 (4) Å, Pd-C(av.) = 1.9648 (16) Å and P-Pd-C = 84.05 (5) and 87.98 (5)°, and O-Pd-O' = 60.56 (4) and 61.13 (4)°. Bonding with the carbonate O atoms shows values of 2.1616 (11) and 2.1452 (11) Å for the Pd-O-Pd bridge, whereas other Pd-O distances are slightly longer at 2.2136 (11) and 2.1946 (11) Å. One of the tert-butyl groups is disordered over two set of sites with an occupancy ratio of 0.723 (6):0.277 (6). Weak C-H⋯O interactions are observed propagating the molecules along the [100] direction.

Microglial phagocytosis induced by fibrillar β-amyloid is attenuated by oligomeric β-amyloid: implications for Alzheimer's disease

Directory of Open Access Journals (Sweden)

Lin Nan

2011-06-01

Full Text Available Abstract Background Reactive microglia are associated with β-amyloid (Aβ deposit and clearance in Alzhiemer's Disease (AD. Paradoxically, entocranial resident microglia fail to trigger an effective phagocytic response to clear Aβ deposits although they mainly exist in an "activated" state. Oligomeric Aβ (oAβ, a recent target in the pathogenesis of AD, can induce more potent neurotoxicity when compared with fibrillar Aβ (fAβ. However, the role of the different Aβ forms in microglial phagocytosis, induction of inflammation and oxidation, and subsequent regulation of phagocytic receptor system, remain unclear. Results We demonstrated that Aβ(1-42 fibrils, not Aβ(1-42 oligomers, increased the microglial phagocytosis. Intriguingly, the pretreatment of microglia with oAβ(1-42 not only attenuated fAβ(1-42-triggered classical phagocytic response to fluorescent microspheres but also significantly inhibited phagocytosis of fluorescent labeled fAβ(1-42. Compared with the fAβ(1-42 treatment, the oAβ(1-42 treatment resulted in a rapid and transient increase in interleukin 1β (IL-1β level and produced higher levels of tumor necrosis factor-α (TNF-α, nitric oxide (NO, prostaglandin E2 (PGE2 and intracellular superoxide anion (SOA. The further results demonstrated that microglial phagocytosis was negatively correlated with inflammatory mediators in this process and that the capacity of phagocytosis in fAβ(1-42-induced microglia was decreased by IL-1β, lippolysaccharide (LPS and tert-butyl hydroperoxide (t-BHP. The decreased phagocytosis could be relieved by pyrrolidone dithiocarbamate (PDTC, a nuclear factor-κB (NF-κB inhibitor, and N-acetyl-L-cysteine (NAC, a free radical scavenger. These results suggest that the oAβ-impaired phagocytosis is mediated through inflammation and oxidative stress-mediated mechanism in microglial cells. Furthermore, oAβ(1-42 stimulation reduced the mRNA expression of CD36, integrin β1 (Itgb1, and Ig

Transcriptomic responses of European flounder (Platichthys flesus) to model toxicants

Energy Technology Data Exchange (ETDEWEB)

Williams, Tim D. [School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)], E-mail: t.d.williams@bham.ac.uk; Diab, Amer [Institute of Aquaculture, University of Stirling, Stirling, Scotland FK9 4LA (United Kingdom); Ortega, Fernando [School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Sabine, Victoria S. [Institute of Aquaculture, University of Stirling, Stirling, Scotland FK9 4LA (United Kingdom); Godfrey, Rita E.; Falciani, Francesco; Chipman, J. Kevin [School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); George, Stephen G. [Institute of Aquaculture, University of Stirling, Stirling, Scotland FK9 4LA (United Kingdom)

2008-11-11

The temporal transcriptomic responses in liver of Platichthys flesus to model environmental pollutants were studied over a 16-day time span after intraperitoneal injection with cadmium chloride (50 {mu}g/kg in saline), 3-methylcholanthrene (25 mg/kg in olive oil), Aroclor 1254 (50 mg/kg in olive oil), tert-butyl-hydroperoxide (5 mg/kg in saline), Lindane (25 mg/kg in olive oil), perfluoro-octanoic acid (100 mg/kg in olive oil) and their vehicles, olive oil (1 ml/kg) or saline (0.9%). Statistical, gene ontology and supervised analysis clearly demonstrated the progression from acute effects, biological responses to and recovery from the treatments. Key biological processes disturbed by the individual treatments were characterised by gene ontology analyses and individual toxicant-responsive genes and pathways were identified by supervised analyses. Responses to the polyaromatic and chlorinated aromatic compounds showed a degree of commonality but were distinguishable and they were clearly segregated from the responses to the pro-oxidants cadmium and the organic hydroperoxide, as well as from the peroxisomal proliferator, perfluoro-octanoic acid. This study demonstrated the utility of the microarray technique in the identification of toxicant-responsive genes and in discrimination between modes of toxicant action.

Transcriptomic responses of European flounder (Platichthys flesus) to model toxicants

International Nuclear Information System (INIS)

Williams, Tim D.; Diab, Amer; Ortega, Fernando; Sabine, Victoria S.; Godfrey, Rita E.; Falciani, Francesco; Chipman, J. Kevin; George, Stephen G.

2008-01-01

The temporal transcriptomic responses in liver of Platichthys flesus to model environmental pollutants were studied over a 16-day time span after intraperitoneal injection with cadmium chloride (50 μg/kg in saline), 3-methylcholanthrene (25 mg/kg in olive oil), Aroclor 1254 (50 mg/kg in olive oil), tert-butyl-hydroperoxide (5 mg/kg in saline), Lindane (25 mg/kg in olive oil), perfluoro-octanoic acid (100 mg/kg in olive oil) and their vehicles, olive oil (1 ml/kg) or saline (0.9%). Statistical, gene ontology and supervised analysis clearly demonstrated the progression from acute effects, biological responses to and recovery from the treatments. Key biological processes disturbed by the individual treatments were characterised by gene ontology analyses and individual toxicant-responsive genes and pathways were identified by supervised analyses. Responses to the polyaromatic and chlorinated aromatic compounds showed a degree of commonality but were distinguishable and they were clearly segregated from the responses to the pro-oxidants cadmium and the organic hydroperoxide, as well as from the peroxisomal proliferator, perfluoro-octanoic acid. This study demonstrated the utility of the microarray technique in the identification of toxicant-responsive genes and in discrimination between modes of toxicant action

Four coordination polymers based on 5-tert-butyl isophthalic acid and rigid bis(imidazol-1yl)benzene linkers: Synthesis, luminescence detection of acetone and optical properties

International Nuclear Information System (INIS)

Arıcı, Mürsel; Zafer Yeşilel, Okan; Büyükgüngör, Orhan

2017-01-01

detection of acetone. Moreover, thermal and optical properties of the complexes were also studied. - Highlights: • Four new 2D and 3D coordination polymers with 5-tert-butyl isophthalic acid and rigid bis(imidazol-1yl)benzene linkers. • The structural diversity depending on ligands and coordination number of metal centers. • Fluorescent sensor for the detection of acetone.

Two wheat glutathione peroxidase genes whose products are located in chloroplasts improve salt and H2O2 tolerances in Arabidopsis.

Directory of Open Access Journals (Sweden)

Chao-Zeng Zhai

Full Text Available Oxidative stress caused by accumulation of reactive oxygen species (ROS is capable of damaging effects on numerous cellular components. Glutathione peroxidases (GPXs, EC 1.11.1.9 are key enzymes of the antioxidant network in plants. In this study, W69 and W106, two putative GPX genes, were obtained by de novo transcriptome sequencing of salt-treated wheat (Triticum aestivum seedlings. The purified His-tag fusion proteins of W69 and W106 reduced H2O2 and t-butyl hydroperoxide (t-BHP using glutathione (GSH or thioredoxin (Trx as an electron donor in vitro, showing their peroxidase activity toward H2O2 and toxic organic hydroperoxide. GFP fluorescence assays revealed that W69 and W106 are localized in chloroplasts. Quantitative real-time PCR (Q-RT-PCR analysis showed that two GPXs were differentially responsive to salt, drought, H2O2, or ABA. Isolation of the W69 and W106 promoters revealed some cis-acting elements responding to abiotic stresses. Overexpression of W69 and W106 conferred strong tolerance to salt, H2O2, and ABA treatment in Arabidopsis. Moreover, the expression levels of key regulator genes (SOS1, RbohD and ABI1/ABI2 involved in salt, H2O2 and ABA signaling were altered in the transgenic plants. These findings suggest that W69 and W106 not only act as scavengers of H2O2 in controlling abiotic stress responses, but also play important roles in salt and ABA signaling.

Atomic layer deposition of GeO{sub 2} thin films on Si(100) using Ge(N,N'-R,R-en)(NMe{sub 2}){sub 2} (where R = Isopropyl and t-Butyl) precursors

Energy Technology Data Exchange (ETDEWEB)

Kim, Dae Hyun; Shin, Jin Ho [Soulbrain Sigma-Aldrich Co., Ltd., Gongju (Korea, Republic of); Jung, Jae Sun; Kang, Jun Gill [Chungnam National University, Daejeon (Korea, Republic of)

2015-08-15

In this study, we introduced bis(dimethylamino)(N,N'-diisopropyl-ethylenediamine) germanium (1) and bis (dimethyl-amino)(N,N'-di-tert-butyl-ethylenediamine) germanium (2) as novel ALD precursors and analyzed the ALD growth characteristics to obtain the best possible film properties. A 5-L three-neck flask was charged with 2.5 L of toluene, GeCl{sub 4} (60 g, 0.28 mol) was added and then cooled to -15 to -20 .deg. C. the two precursors produced good-quality GeO{sub 2} thin films via the ALD process. The ALD windows of bis(dimethylamino)(N,N'-di-isopropyl-ethylenediamine) germanium and bis(dimethylamino)(N,N'-di-tert -butyl-ethylene-diamine) germanium were established at 200–330 .deg. C with a growth rate of about 0.40 and 0.31 Å/cycle, respectively. ALD-type growth mode was verified by increasing the precursor pulsing time. Growth rate was saturated from 3.0 s. These films have considerable potential for industrial applications.

Hydroperoxide Measurements During Low-Temperature Gas-Phase Oxidation of n-Heptane and n-Decane

KAUST Repository

Rodriguez, Anne

2017-02-13

A wide range of hydroperoxides (C-C alkyl hydroperoxides, C-C alkenyl hydroperoxides, C ketohydroperoxides, and hydrogen peroxide (HO)), as well as ketene and diones, have been quantified during the gas-phase oxidation of n-heptane. Some of these species, as well as C alkenyl hydroperoxides and ketohydroperoxides, were also measured during the oxidation of n-decane. These experiments were performed using an atmospheric-pressure jet-stirred reactor at temperatures from 500 to 1100 K and one of three analytical methods, time-of-flight mass spectrometry combined with tunable synchrotron photoionization with a molecular beam sampling: time-of-flight mass spectrometry combined with laser photoionization with a capillary tube sampling, continuous wave cavity ring-down spectroscopy with sonic probe sampling. The experimental temperature at which the maximum mole fraction is observed increases significantly for alkyl hydroperoxides, alkenyl hydroperoxides, and then more so again for hydrogen peroxide, compared to ketohydroperoxides. The influence of the equivalence ratio from 0.25 to 4 on the formation of these peroxides has been studied during n-heptane oxidation. The up-to-date detailed kinetic oxidation models for n-heptane and for n-decane found in the literature have been used to discuss the possible pathways by which these peroxides, ketene, and diones are formed. In general, the model predicts well the reactivity of the two fuels, as well as the formation of major intermediates. (Figure Presented).

Hydroperoxide Measurements During Low-Temperature Gas-Phase Oxidation of n-Heptane and n-Decane

KAUST Repository

Rodriguez, Anne; Herbinet, Olivier; Meng, Xiangzan; Fittschen, Christa; Wang, Zhandong; Xing, Lili; Zhang, Lidong; Battin-Leclerc, Fré dé rique

2017-01-01

A wide range of hydroperoxides (C-C alkyl hydroperoxides, C-C alkenyl hydroperoxides, C ketohydroperoxides, and hydrogen peroxide (HO)), as well as ketene and diones, have been quantified during the gas-phase oxidation of n-heptane. Some of these species, as well as C alkenyl hydroperoxides and ketohydroperoxides, were also measured during the oxidation of n-decane. These experiments were performed using an atmospheric-pressure jet-stirred reactor at temperatures from 500 to 1100 K and one of three analytical methods, time-of-flight mass spectrometry combined with tunable synchrotron photoionization with a molecular beam sampling: time-of-flight mass spectrometry combined with laser photoionization with a capillary tube sampling, continuous wave cavity ring-down spectroscopy with sonic probe sampling. The experimental temperature at which the maximum mole fraction is observed increases significantly for alkyl hydroperoxides, alkenyl hydroperoxides, and then more so again for hydrogen peroxide, compared to ketohydroperoxides. The influence of the equivalence ratio from 0.25 to 4 on the formation of these peroxides has been studied during n-heptane oxidation. The up-to-date detailed kinetic oxidation models for n-heptane and for n-decane found in the literature have been used to discuss the possible pathways by which these peroxides, ketene, and diones are formed. In general, the model predicts well the reactivity of the two fuels, as well as the formation of major intermediates. (Figure Presented).

Synthesis and characterization of novel bioactive 1,2,4-oxadiazole natural product analogs bearing the N-phenylmaleimide and N-phenylsuccinimide moieties

Directory of Open Access Journals (Sweden)

Catalin V. Maftei

2013-10-01

Full Text Available Taking into consideration the biological activity of the only natural products containing a 1,2,4-oxadiazole ring in their structure (quisqualic acid and phidianidines A and B, the natural product analogs 1-(4-(3-tert-butyl-1,2,4-oxadiazol-5-ylphenylpyrrolidine-2,5-dione (4 and 1-(4-(3-tert-butyl-1,2,4-oxadiazol-5-ylphenyl-1H-pyrrole-2,5-dione (7 were synthesized starting from 4-(3-tert-butyl-1,2,4-oxadiazol-5-ylaniline (1 in two steps by isolating the intermediates 4-(4-(3-tert-butyl-1,2,4-oxadiazol-5-ylphenylamino-4-oxobutanoic acid (3 and (Z-4-(4-(3-tert-butyl-1,2,4-oxadiazol-5-ylphenylamino-4-oxobut-2-enoic acid (6. The two natural product analogs 4 and 7 were then tested for antitumor activity toward a panel of 11 cell lines in vitro by using a monolayer cell-survival and proliferation assay. Compound 7 was the most potent and exhibited a mean IC50 value of approximately 9.4 µM. Aniline 1 was synthesized by two routes in one-pot reactions starting from tert-butylamidoxime and 4-aminobenzoic acid or 4-nitrobenzonitrile. The structures of compounds 1, 2, 4, 5 and 6 were confirmed by X-ray crystallography.

Histone H1- and other protein- and amino acid-hydroperoxides can give rise to free radicals which oxidize DNA

DEFF Research Database (Denmark)

Luxford, C; Morin, B; Dean, R T

1999-01-01

analysis has demonstrated that radicals from histone H1-hydroperoxides, and other protein and amino acid hydroperoxides, can also oxidize both free 2'-deoxyguanosine and intact calf thymus DNA to give the mutagenic oxidized base 7, 8-dihydro-8-oxo-2'-deoxyguanosine (8-hydroxy-2'-deoxyguanosine, 8-oxod......Exposure of amino acids, peptides and proteins to radicals, in the presence of oxygen, gives high yields of hydroperoxides. These materials are readily decomposed by transition metal ions to give further radicals. We hypothesized that hydroperoxide formation on nuclear proteins, and subsequent...... decomposition of these hydroperoxides to radicals, might result in oxidative damage to associated DNA. We demonstrate here that exposure of histone H1 and model compounds to gamma-radiation in the presence of oxygen gives hydroperoxides in a dose-dependent manner. These hydroperoxides decompose to oxygen...

Formation of singlet oxygen by decomposition of protein hydroperoxide in photosystem II.

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Vinay Pathak

Full Text Available Singlet oxygen (1O2 is formed by triplet-triplet energy transfer from triplet chlorophyll to O2 via Type II photosensitization reaction in photosystem II (PSII. Formation of triplet chlorophyll is associated with the change in spin state of the excited electron and recombination of triplet radical pair in the PSII antenna complex and reaction center, respectively. Here, we have provided evidence for the formation of 1O2 by decomposition of protein hydroperoxide in PSII membranes deprived of Mn4O5Ca complex. Protein hydroperoxide is formed by protein oxidation initiated by highly oxidizing chlorophyll cation radical and hydroxyl radical formed by Type I photosensitization reaction. Under highly oxidizing conditions, protein hydroperoxide is oxidized to protein peroxyl radical which either cyclizes to dioxetane or recombines with another protein peroxyl radical to tetroxide. These highly unstable intermediates decompose to triplet carbonyls which transfer energy to O2 forming 1O2. Data presented in this study show for the first time that 1O2 is formed by decomposition of protein hydroperoxide in PSII membranes deprived of Mn4O5Ca complex.

Monitoring of BHT-quinone and BHT-CHO in the gas of capsules of Asclepias physocarpa.

Science.gov (United States)

Ma, Bing-Ji; Peng, Hua; Liu, Ji-Kai

2006-01-01

Three volatile components, namely benzoic acid ethyl ester (1), 2,6-di-tert-butyl-p-benzoquinone (BHT-quinone) (2), and 3,5-di-tert-butyl-4-hydroxybenzaldehyde (BHT-CHO) (3), were detected from the gas in the capsules of Asclepias physocarpa by means of GC/MS analysis. BHT-quinone and BHT-CHO as organic pollutants are the degradation products of the antioxidant 2,6-di-tert-butyl-4-methylphenol (BHT). Ground water, lake water and/or rain water are a source of BHT metabolites in the plant Asclepias physocarpa.

Aromatic oligoamides with a rare ortho-connectivity

DEFF Research Database (Denmark)

Hjelmgaard, T.; Nielsen, John

2013-01-01

studies indicated a more restricted rotation about the amide bonds in ortho-arylopeptoids, presumably due to a more congested backbone structure resulting from the ortho-connectivity pattern. Intriguingly, tert-butyl and phenyl side chains offer complete control over the amide conformations; whereas...... arylopeptoid residues with tert-butyl side chains adopt a 100 % cis amide conformation, the opposite 100 % trans amide conformation was observed in arylopeptoids with phenyl side chains. The tert-butyl moiety can furthermore serve as a protecting group during synthesis, which can later be removed to allow...

Atmospheric measurements of hydroperoxides and aldehydes during field campaigns : new results due to improvement of measurements techniques

Science.gov (United States)

François, S.; Sowka, I.; Poulain, L.; Monod, A.; Wortham, H.

2003-04-01

Hydroperoxides and aldehydes are considered as atmospheric reservoirs of OH, HO_2 and RO_2 radicals and can reflect the oxidizing levels of the atmosphere. They are considered as important gas phase photo-oxidants present in the atmosphere. However, the atmospheric role of these compounds can vary from one species to another, therefore it is essential to investigate their measurement and speciation in the atmosphere. Atmospheric measurements were realized during two different field campaigns in the Marseilles area (France). Hydroperoxides were trapped in aqueous phase, with a glass coil and analyzed by HPLC/fluorescence detector with post column derivatization. Aldehydes were trapped in a liquid phase containing 2-4 DNPH, with a mist chamber and analyzed by HPLC/UV. The analytical techniques provided individual separation and quantification of seven hydroperoxides (hydrogen peroxide, hydroxymethyl hydroperoxide, bis(hydroxymethyl) peroxide, 1-hydroxyethyl hydroperoxide, methyl hydroperoxide, ethyl hydroperoxide and peroxyacetic acid) and eleven volatile aldehydes (formaldehyde, acetaldehyde, acrolein, acetone, propionaldehyde, crotonaldehyde, butyraldehyde, benzaldehyde, glyoxal, valeraldehyde and methylglyoxal). The first field campaign was part of the ESCOMPTE project (June 4th to July 16th 2001). During this campaign five different sampling sites, at low altitudes (<= 285 m), were investigated (maritime, urban, sub-industrial, biogenic and rural sites) and atmospheric measurements were realized during photochemical air pollution events. The second field campaign was part of the BOND project (July 2nd to July 14th 2002). Atmospheric measurements of hydroperoxides were carried out on one biogenic site, at altitude 690 m. The measurement system was improved allowing online sampling and analysis. During these field campaigns collection efficiencies were better than 96% for hydroperoxides, and from 78% to 96% for aldehydes. Detection limits were between 7,3× 10-3 �

Steric/π-electronic insulation of the carbo-benzene ring: dramatic effects of tert-butyl vs phenyl crowns on geometric, chromophoric, redox and magnetic properties.

Science.gov (United States)

Listunov, Dymytrii; Duhayon, Carine; Poater, Albert; Mazères, Serge; Saquet, Alix; Maraval, Valérie; Chauvin, Remi

2018-04-13

Hexa-tert-butyl-carbo-benzene C18tBu6 and three phenylated counterparts C18tBumPh6-m (m = 4, 2) have been synthesized. The peralkylated version (m = 6) provides experimental access to intrinsic features of the insulated C18 core independently from the influence of π-conjugated substituent. Over the series, structural, spectroscopical and electrochemical properties are compared with those of the hexaphenylated reference (m = 0). Anchoring tBu substituents at the C18 macrocycle is shown to enhance stability and solubility, and to dramatically modify UV-vis absorption and redox properties. Whereas all the carbo-benzenes reported hitherto were obtained as dark-reddish/greenish solids, crystals and solutions of C18tBu6 happen to be yellow (max = 379 nm vs 472 nm for C18Ph6). By comparison to C18Ph6, reduction of C18tBu6 remains reversible but occurs at a twice higher absolute potential (E1/2 = -1.36 V vs -0.72 V). Systematic X-ray diffraction analyses and DFT calculations show that the C18 ring symmetry is the nearest to D6h for m = 6, indicating a maximum geometrical aromaticity. According to calculated nucleus independent chemical shifts, the macrocyclic magnetic aromaticity is also found to be maximum for C18tBu6: NICS(0)=-17.2 ppm, vs -18.0±0.1 ppm for the theoretical references C18H6 and C18F6, and -13.5 ppm for C18Ph6. Accurate correlations of NICS(0) with experimental or calculated maximum UV-vis absorption wavelength max and chemical hardness =ELUMO-EHOMO are evidenced. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Recovering/recycling of butyl and halogenated butyl rubber via ionizing radiation

International Nuclear Information System (INIS)

Martin, Sandra Regina Scagliusi

2013-01-01

Polymeric materials (plastics and rubbers) attain a continuous and raising proportion of urban and industrial scraps discarded in landfills; their impact on environment are more and more concerning. The implementation of new technologies in order to reduce impacts of plastic waste on the environment, at an effective cost, proved to be a great problem, due to inherent complexity for polymers re-using. Ionizing radiation is capable to modify structure and properties of polymeric material. Butyl and halobutyl rubbers have been used within a comprehensive scale, applications such as tires spare parts and diverse artifacts. The major high energy photon effect, as gamma-rays in butyl and halo butyl rubbers consists in free-radicals generation along changes in mechanical properties.This work aims to the development of controlled degradation processes (devulcanization) of butyl and halo butyl (chlorine and bromine) rubbers, in order to characterize their availability for transformation and modification of properties. Experimental results obtained showed that butyl and halobutyl rubbers,irradiated at 25 kGy and further sheared, are able to be used as an initial point for mixtures with pristine. (author)

Preparation, Characterization and Efficacy Evaluation of Synthetic Biocompatible Polymers Linking Natural Antioxidants

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Nevio Picci

2012-10-01

Full Text Available The purpose of this work was the synthesis, characterization and efficacy evaluation of new biocompatible antioxidant polymers linking trans-ferulic acid or a-lipoic acid. In particular, ferulic or lipoic acid were introduced in the preformed polymeric backbone. The new antioxidant biopolymers were characterized by Fourier transform infrared spectroscopy and gel permeation chromatography. The degree of functionalization (moles of antioxidant per gram of polymer was determined by the Gaur-Gupta method for free amino group determination and by the Folin method for the phenolic groups. Their ability to inhibit lipid peroxidation were estimated in rat liver microsomal membranes induced in vitro by tert-BOOH (tert-butyl hydroperoxide, as a source of free radicals. The DPPH (1,1-diphenyl-2-picrylhydrazyl radical-scavenging effect was also evaluated. The obtained systems, with different solubility, showed strong antioxidant and antiradical activities, suggesting potential use as packaging materials for foods, cosmetics, pharmaceuticals and personal care products. Moreover, the cytotoxicity of the synthesized polymers was also evaluated on Caco-2 cell cultures in order to verify their biocompatibility when exposed to an absorptive epithelial cell line.

Metal halide-phosphorus halide-alkyl halide complexes: reaction with niobium and tantalum pentachlorides

International Nuclear Information System (INIS)

Puri, D.M.; Saini, M.S.

1978-01-01

The reactions of niobium and tantalum pentachlorides with trichlorophosphine and phenyldichlorophosphine have been studied in presence of alkylating agents such as sec-butyl chloride, iso-butyl chloride, tert-butyl chloride, tert-anylchloride, cyclohexyl chloride and triphenylmethyl chloride. Solid products have been isolated and characterised by vibrational spectroscopy as ionic complexes of alkyl- and/or aryl-phosphonium cations with hexachloroniobate and hexachlorotantalate anions. (author)

A dioxygenase of Pleurotus sapidus transforms (+)-valencene regio-specifically to (+)-nootkatone via a stereo-specific allylic hydroperoxidation.

Science.gov (United States)

Krügener, Sven; Krings, Ulrich; Zorn, Holger; Berger, Ralf G

2010-01-01

A selective and highly efficient allylic oxidation of the sesquiterpene (+)-valencene to the grapefruit flavour compound (+)-nootkatone was achieved with lyophilisate of the edible mushroom Pleurotus sapidus. The catalytic reaction sequence was elucidated through the identification of intermediate, (+)-valencene derived hydroperoxides. A specific staining of hydroperoxides allowed the semi-preparative isolation of two secondary (+)-valencene hydroperoxides, 6(R)-Isopropenyl-4(R),4a(S)-dimethyl-2,3,4,4a,5,6,7,8-octahydro-naphthalen-4(S)-yl-hydroperoxide and 6(R)-Isopropenyl-4(R),4a(S)-dimethyl-2,3,4,4a,5,6,7,8-octahydro-naphthalen-2(R)-yl-hydroperoxide. Chemical reduction of the biotransformation products yielded a tertiary alcohol identified as 2(R)-Isopropenyl-8(R),8a(S)-dimethyl-1,3,4,7,8,8a-hexahydro-2H-naphthalen-4a(R)-ol. This suggested a lipoxygenase-type oxidation of (+)-valencene via secondary and tertiary hydroperoxides and confirmed homology data of the key enzyme obtained previously from amino acid sequencing.

Induction of peroxide and superoxide protective enzymes and physiological cross-protection against peroxide killing by a superoxide generator in Vibrio harveyi.

Science.gov (United States)

Vattanaviboon, Paiboon; Panmanee, Warunya; Mongkolsuk, Skorn

2003-04-11

Vibrio harveyi is a causative agent of destructive luminous vibriosis in farmed black tiger prawn (Penaeus monodon). V. harveyi peroxide and superoxide stress responses toward elevated levels of a superoxide generated by menadione were investigated. Exposure of V. harveyi to sub-lethal concentrations of menadione induced high expression of genes in both the OxyR regulon (e.g., a monofunctional catalase or KatA and an alkyl hydroperoxide reductase subunit C or AhpC), and the SoxRS regulon (e.g., a superoxide dismutase (SOD) and a glucose-6-phosphate dehydrogenase). V. harveyi expressed two detectable, differentially regulated SOD isozymes, [Mn]-SOD and [Fe]-SOD. [Fe]-SOD was expressed constitutively throughout the growth phase while [Mn]-SOD was expressed at the stationary phase and could be induced by a superoxide generator. Physiologically, pre-treatment of V. harveyi with menadione induced cross-protection against subsequent exposure to killing concentrations of H(2)O(2). This induced cross-protection required newly synthesized proteins. However, the treatment did not induce significant protection against exposures to killing concentrations of menadione itself or cross-protect against an organic hydroperoxide (tert-butyl hydroperoxide). Unexpectedly, growing V. harveyi in high-salinity media induced protection against menadione killing. This protection was independent of SOD induction. Stationary-phase cells were more resistant to menadione killing than exponential-phase cells. The induction of oxidative stress protective enzymes and stress-altered physiological responses could play a role in the survival of this bacterium in the host marine crustaceans.

FEATURES OF INITIATION OF STYRENE POLYMERIZATION BY CUMENE HYDROPEROXIDE IN PRESENCE OF ACETULACETONATE OF COPPER(II

Directory of Open Access Journals (Sweden)

A. V. Grekova

2016-04-01

Full Text Available Kinetics of sectional styrene polymerization initiated by cumene hydroperoxide, acetylacetonate of copper(II and by the system of cumene hydroperoxide — acetylacetonate of copper(II in a temperature range 333-363 K is studied. Kinetic parameters of polymerization process are determined. It is shown, that system of cumene hydroperoxide — acetylacetonate of copper(II is in 5-6 times more effective on the initiating ability comparatively to application of its individual components. From findings ensues that decline of energy of activating of initiation from 110 kdzh/mol’ to 87 kdzh/mol’ for cumene hydroperoxide at the use of the studied system is caused with participating of monomer in preliminary complexation facilitating formation of free radicals.

Four coordination polymers based on 5-tert-butyl isophthalic acid and rigid bis(imidazol-1yl)benzene linkers: Synthesis, luminescence detection of acetone and optical properties

Energy Technology Data Exchange (ETDEWEB)

Arıcı, Mürsel, E-mail: marici@ogu.edu.tr [Department of Chemistry, Faculty of Arts and Sciences, Eskişehir Osmangazi University, 26480 Eskişehir (Turkey); Zafer Yeşilel, Okan [Department of Chemistry, Faculty of Arts and Sciences, Eskişehir Osmangazi University, 26480 Eskişehir (Turkey); Büyükgüngör, Orhan [Department of Physics, Faculty of Arts and Sciences, Ondokuz Mayıs University, 55139 Samsun (Turkey)

2017-05-15

methanol could be used as a fluorescent sensor for the detection of acetone. Moreover, thermal and optical properties of the complexes were also studied. - Highlights: • Four new 2D and 3D coordination polymers with 5-tert-butyl isophthalic acid and rigid bis(imidazol-1yl)benzene linkers. • The structural diversity depending on ligands and coordination number of metal centers. • Fluorescent sensor for the detection of acetone.

Catalytic hydrolysis of Metil Teret Botil Eter in under ground contaminated water

International Nuclear Information System (INIS)

Nikpey, A.; Mortazavi, B.; Asilian, H.; Khavanin, A.; Rezaee, A.; Soleimanian, A.; Kazemian, H.

2005-01-01

The behavior of ZSM-5 and Mordenite catalyst in the hydrolysis at room temperature of methyl tert-butyl ether was studied with reference to the possibility of its conversion to more biodegradable products in underground water contaminated by methyl tert-butyl ether. Hydrolysis products were determined using a gas chromatograph equipped with a flame ionization detector. The results indicate that acid ZSM-5 catalyst are effective in both adsorption and hydrolysis of methyl tert-butyl ether and may be applied for both in situ underground water remediation and as protection barrier for wells or leaking tanks. However, acid mordenite catalyst completely inactive

Synthesis, characterization and computational studies of (E-2-{[(2-aminopyridin-3-ylimino]-methyl}-4,6-di-tert-butylphenol

Directory of Open Access Journals (Sweden)

Alexander Carreño

2014-01-01

Full Text Available (E-2-{[(2-Aminopyridin-3-ylimino]-methyl}-4,6-di-tert-butyl-phenol ( 3: , a ligand containing an intramolecular hydrogen bond, was prepared according to a previous literature report, with modifications, and was characterized by UV-vis, FTIR, ¹H-NMR, 13C-NMR, HHCOSY, TOCSY and cyclic voltammetry. Computational analyses at the level of DFT and TD-DFT were performed to study its electronic and molecular structures. The results of these analyses elucidated the behaviors of the UV-vis and electrochemical data. Analysis of the transitions in the computed spectrum showed that the most important band is primarily composed of a HOMO→LUMO transition, designated as an intraligand (IL charge transfer.

The organic air pollutant cumene hydroperoxide interferes with NO antioxidant role in rehydrating lichen

International Nuclear Information System (INIS)

Catalá, M.; Gasulla, F.; Pradas del Real, A.E.; García-Breijo, F.; Reig-Armiñana, J.; Barreno, E.

2013-01-01

Organic pollutants effects on lichens have not been addressed. Rehydration is critical for lichens, a burst of free radicals involving NO occurs. Repeated dehydrations with organic pollutants could increase oxidative damage. Our aim is to learn the effects of cumene hydroperoxide (CP) during lichen rehydration using Ramalina farinacea (L.) Ach., its photobiont Trebouxia spp. and Asterochloris erici. Confocal imaging shows intracellular ROS and NO production within myco and phycobionts, being the chloroplast the main source of free radicals. CP increases ROS, NO and lipid peroxidation and reduces chlorophyll autofluorescence, although photosynthesis remains unaffected. Concomitant NO inhibition provokes a generalized increase of ROS and a decrease in photosynthesis. Our results suggest that CP induces a compensatory hormetic response in Ramalina farinacea that could reduce the lichen's antioxidant resources after repeated desiccation-rehydration cycles. NO is important in the protection from CP. -- Highlights: •Organic pollutants could be involved in lichen decline but effects are unknown. •Cumene hydroperoxide induces a compensatory response in rehydration (hormesis). •Cumene hydroperoxide induces a delayed lipid peroxidation. •NO is involved in rehydration oxidative stress regulation under cumene hydroperoxide. •Symbionts display specific responses probably involving communication along time. -- The organic air pollutant cumene hydroperoxide induces oxidative membrane damage in the lichen Ramalina farinacea during rehydration. Nitric oxide (NO) is involved in lichen response

Crystal structure of (1R,4R-tert-butyl 3-oxo-2-oxa-5-azabicyclo[2.2.2]octane-5-carboxylate

Directory of Open Access Journals (Sweden)

Suvratha Krishnamurthy

2015-07-01

Full Text Available In the title compound, C11H17NO4, commonly known as N-tert-butoxycarbonyl-5-hydroxy-d-pipecolic acid lactone, the absolute configuration is (1R,4R due to the enantiomeric purity of the starting material which remains unchanged during the course of the reaction. In the crystal there no intermolecular hydrogen bonds.

Hydroperoxide production from linoleic acid by heterologous Gaeumannomyces graminis tritici lipoxygenase: Optimization and scale-up

NARCIS (Netherlands)

Villaverde, J.J.; Vlist, van der V.; Santos, S.A.O.; Haarmann, T.; Langfelder, K.; Pirttimaa, M.; Nyyssola, A.; Jylhä, S.; Tamminen, T.; Kruus, K.; Graaff, de L.H.; Pascoal Neto, C.; Simoes, M.M.Q.; Domingues, M.R.M.; Silvestre, A.J.D.; Eidner, J.; Buchert, J.

2013-01-01

Linoleic acid was converted into hydroperoxides by a Gaeumannomyces graminis tritici lipoxygenase produced recombinantly in Trichoderma reesei. Hydroperoxide production was optimized using a face-centred experimental design in order to study the effects of pH, temperature and time on the conversion

STABLE ISOTOPE ANALYSIS OF MTBE TO EVALUATE THE SOURCE OF TBA IN GROUND WATER

Science.gov (United States)

Although tert-butyl alcohol (TBA) has not been used as a fuel oxygenate in Orange County, California, the concentrations of TBA in ground water at gasoline spill sites are high compared those of the conventional fuel oxygenate methyl tert-butyl ether (MTBE). In the year 2002, th...

ANAEROBIC DEGRADATION OF MTBE TO TBA IN GROUND WATER AT GASOLINE SPILL SITES IN ORANGE COUNTY, CALIFORNIA

Science.gov (United States)

Although tert-Butyl Alcohol (TBA) has not been used as a fuel oxygenate in Orange County, California, the concentrations of TBA in ground water at gasoline spill sites are high compared to the concentrations of the conventional fuel oxygenate Methyl tert-Butyl Ether (MTBE). In t...

Encapsulation and release by star-shaped block copolymers as unimolecular nanocontainers

NARCIS (Netherlands)

Kul, D.; Renterghem, van L.M.; Meier, M.A.R.; Strandman, S.; Tenhu, H.; Yilmaz, S.S.; Schubert, U.S.; Du Prez, F.E.

2008-01-01

Five-arm star-shaped poly(ethylene oxide) (PEO) with terminal bromide groups was used as a macroinitiator for the atom transfer radical polymerization of tert-butyl acrylate (tBA), resulting in five-arm star-shaped poly(ethylene oxide)-block-poly(tert-butyl acrylate) block copolymers. The

Adduction of DNA with MTBE and TBA in mice studied by accelerator mass spectrometry.

Science.gov (United States)

Yuan, Y; Wang, H F; Sun, H F; Du, H F; Xu, L H; Liu, Y F; Ding, X F; Fu, D P; Liu, K X

2007-12-01

Methyl tert-butyl ether (MTBE) is a currently worldwide used octane enhancer substituting for lead alkyls and gasoline oxygenate. Our previous study using doubly (14)C-labeled MTBE [(CH(3))(3) (14)CO(14)CH(3)] has shown that MTBE binds DNA to form DNA adducts at low dose levels in mice. To elucidate the mechanism of the binding reaction, in this study, the DNA adducts with singly (14)C-labeled MTBE, which was synthesized from (14)C-methanol and tert-butyl alcohol (TBA), or (14)C-labeled TBA in mice have been measured by ultra sensitive accelerator mass spectrometry. The results show that the methyl group of MTBE and tert-butyl alcohol definitely form adducts with DNA in mouse liver, lung, and kidney. The methyl group of MTBE is the predominant binding part in liver, while the methyl group and the tert-butyl group give comparable contributions to the adduct formation in lung and kidney.

Can contact allergy to p-phenylenediamine explain the high rates of terpene hydroperoxide allergy?

DEFF Research Database (Denmark)

Bennike, Niels Højsager; Lepoittevin, Jean Pierre; Johansen, Jeanne D.

2017-01-01

Background: Contact allergy to linalool hydroperoxides (Lin-OOHs) and limonene hydroperoxides (Lim-OOHs) is common. Similarly to what occurs with the terpene hydroperoxides, reactive intermediates formed from p-phenylenediamine (PPD) can cause oxidative modifications of tryptophan residues...... on proteins in mechanistic studies. Objectives: To test the hypothesis that patients sensitized to PPD are at increased risk of concomitant reactivity to either of the terpene hydroperoxides, owing to a ‘common pathway’ of skin protein oxidation. Methods: A database study of consecutively patch tested eczema...... patients (n = 3843) from 2012 to 2015, tested concomitantly with PPD, Lim-OOHs and Lin-OOHs, was performed. Associations were examined by level of concordance and odds ratios (ORs) adjusted for age, sex, and contact allergy to fragrance mix I and fragrance mix II. Results: Concomitant reactions to PPD were...

Solubilization of meso-carbon microbeads by potassium- or dibutylzinc-promoted butylation and structural analysis of the butylated products; Mesocarbon microbeads no butyl ka ni yoru kayoka to erareta butyl kabutsu no kozo kaiseki

Energy Technology Data Exchange (ETDEWEB)

Murata, S.; Zhang, Y.; Kidena, K.; Nomura, M. [Osaka University, Osaka (Japan). Faculty of Engineering

1996-10-28

Tetrahydrofuran (THF) solubility and structure of the butylated products of meso-carbon microbeads (MCMB) were studied experimentally. In experiment, MCMB-A and MCMB-B obtained from two kinds of coal-tar pitch were used as specimens. MCMBs were butylated by BZ method using dibutylzinc-butyl iodide and KT method using K-butyl iodide-THF, and the butylated products were successfully obtained. The butylated products were investigated through THF solubility test, {sup 13}C-NMR measurement and gel permeation chromatography (GPC) measurement. As the experimental result, a BZ method produced the butylated products at a yield of nearly 170%, while a KT method produced them at a yield of nearly 130%. The THF solubility was estimated to be 89-97%. As the study result of molecular weight distributions by GPC measurement of solvent solubles, the molecular weight of raw material MCMB was estimated to be 590-770 in terms of polystyrene. 6 refs., 2 figs., 1 tab.

Degradation of carbonyl hydroperoxides in the atmosphere and in combustion

KAUST Repository

Xing, Lili

2017-10-12

Oxygenates with carbonyl and hydroperoxy functional groups are important intermediates that are generated during the autooxidation of organic compounds in the atmosphere and during the autoignition of transport fuels. In the troposphere, the degradation of carbonyl hydroperoxides leads to low-vapor-pressure polyfunctional species that be taken into in cloud and fog droplets or to the formation of secondary organic aerosols (SOAs). In combustion, the fate of carbonyl hydroperoxides is important for the performance of advanced combustion engines, especially for autoignition. A key fate of the carbonyl hydroperoxides is reac-tion with OH radicals, for which kinetics data are experimentally unavailable. Here, we study 4-hydroperoxy-2-pentanone (CH3C(=O)CH2CH(OOH)CH3) as a model compound to clarify the kinetics of OH reactions with carbonyl hydroperoxides, in par-ticular H-atom abstraction and OH addition reactions. With a combination of electronic structure calculations, we determine previ-ously missing thermochemical data, and with multipath variational transition state theory (MP-VTST), a multidimensional tunnel-ing (MT) approximation, multiple-structure anharmonicity, and torsional potential anharmonicity we obtained much more accurate rate constants than the ones that can computed by conventional single-structure harmonic transition state theory (TST) and than the empirically estimated rate constants that are currently used in atmospheric and combustion modeling. The roles of various factors in determining the rates are elucidated. The pressure-dependent rate constants for the addition reaction are computed using system-specific quantum RRK theory. The calculated temperature range is 298-2400 K, and the pressure range is 0.01–100 atm. The accu-rate thermodynamic and kinetics data determined in this work are indispensable in the global modeling of SOAs in atmospheric science and in the detailed understanding and prediction of ignition properties of hydrocarbons

Multiple steady states detection in a packed-bed reactive distillation column using bifurcation analysis

DEFF Research Database (Denmark)

Ramzan, Naveed; Faheem, Muhammad; Gani, Rafiqul

2010-01-01

A packed reactive distillation column producing ethyl tert-butyl ether from tert-butyl alcohol and ethanol was simulated for detection of multiple steady states using Aspen Plus®. A rate-based approach was used to make the simulation model more realistic. A base-case was first developed and fine...

Synthesis, characterization and computational studies of (E)-2-{[(2-aminopyridine-3-yl)imino]-methyl}-4,6-di-tert-butylphenol

Energy Technology Data Exchange (ETDEWEB)

Carreno, Alexander; Vega, Andres, E-mail: ichavez@uc.cl [Departamento de Ciencias Quimicas, Facultad de Ciencias Exactas, Universidad Andres Bello, Santiago (Chile); Zarate, Ximena; Schott, Eduardo [Lab. Bionanotecnologia, Departamento de Ciencias Quimico-Biologicas, Universidad Bernardo O' Higgins, Santiago (Chile); Gacitua, Manuel; Valenzuela, Ninnette; Manriquez, Juan M.; Chavez, Ivonne [Departamento de Quimica Inorganica, Facultad de Quimica, Pontificia Universidad Catolica de Chile, Santiago (Chile); Preite, Marcelo [Departamento de Quimica Inorganica, Facultad de Quimica, Pontificia Universidad Catolica de Chile, Santiago (Chile)

2014-07-01

(E)-2-{[(2-Aminopyridine-3-yl)imino]-methyl}-4,6-di-tert-butyl-phenol ( 3: ), a ligand containing an intramolecular hydrogen bond, was prepared according to a previous literature report, with modifications, and was characterized by UV-vis, FTIR, {sup 1}H-NMR, {sup 13}C-NMR, HHCOSY, TOCSY and cyclic voltammetry. Computational analyses at the level of DFT and TD-DFT were performed to study its electronic and molecular structures. The results of these analyses elucidated the behaviors of the UV-vis and electrochemical data. Analysis of the transitions in the computed spectrum showed that the most important band is primarily composed of a HOMO→LUMO transition, designated as an intraligand (IL) charge transfer. (author)

Enterovirus inhibitory activity of C-8-tert-butyl substituted 4-aryl-6,7,8,9-tetrahydrobenzo[4,5]thieno[3,2-e][1,2,4]triazolo[4,3-a]pyrimidin-5(4H)-ones.

Science.gov (United States)

Kumar Biswas, Bishyajit; Malpani, Yashwardhan R; Ha, Neul; Kwon, Do-Hyun; Soo Shin, Jin; Kim, Hae-Soo; Kim, Chonsaeng; Bong Han, Soo; Lee, Chong-Kyo; Jung, Young-Sik

2017-08-01

Members of a series of 4-aryl-6,7,8,9-tetrahydrobenzo[4,5]thieno[3,2-e][1,2,4]triazolo[4,3-a]pyrimidin-5(4H)-ones (1, Fig. 2) were prepared and tested against representative enteroviruses including Human Coxsackievirus B1 (Cox B1), Human Coxsackievirus B3 (Cox B3), human Poliovirus 3 (PV3), human Rhinovirus 14 (HRV14), human Rhinovirus 21 (HRV 21) and human Rhinovirus 71 (HRV 71). The C-8-tert-butyl group on the tetrahydrobenzene ring in these substances was found to be crucial for their enterovirus activity. One member of this group, 1e, showed single digit micromolar activities (1.6-8.85μM) against a spectrum of viruses screened, and the highest selectivity index (SI) values for Cox B1 (>11.2), for Cox B3 (>11.5), and for PV3 (>51.2), respectively. In contrast, 1p, was the most active analog against the selected HRVs (1.8-2.6μM), and showed the highest selectivity indices among the group of compounds tested. The SI values for 1p were 11.5 for HRV14, 8.4 for HRV21, and 12.1 for HRV71, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

Influence of thermocleavable functionality on organic field-effect transistor performance of small molecules

Science.gov (United States)

Mahale, Rajashree Y.; Dharmapurikar, Satej S.; Chini, Mrinmoy Kumar; Venugopalan, Vijay

2017-06-01

Diketopyrrolopyrrole based donor-acceptor-donor conjugated small molecules using ethylene dioxythiophene as a donor was synthesized. Electron deficient diketopyrrolopyrrole unit was substituted with thermocleavable (tert-butyl acetate) side chains. The thermal treatment of the molecules at 160 °C eliminated the tert-butyl ester group results in the formation of corresponding acid. Optical and theoretical studies revealed that the molecules adopted a change in molecular arrangement after thermolysis. The conjugated small molecules possessed p-channel charge transport characteristics in organic field effect transistors. The charge carrier mobility was increased after thermolysis of tert-butyl ester group to 5.07 × 10-5 cm2/V s.

Recurrent TERT promoter mutations identified in a large-scale study of multiple tumor types are associated with increased TERT expression and telomerase activation

Science.gov (United States)

Huang, Dong-Sheng; Wang, Zhaohui; He, Xu-Jun; Diplas, Bill H.; Yang, Rui; Killela, Patrick J.; Liang, Junbo; Meng, Qun; Ye, Zai-Yuan; Wang, Wei; Jiang, Xiao-Ting; Xu, Li; He, Xiang-Lei; Zhao, Zhong-Sheng; Xu, Wen-Juan; Wang, Hui-Ju; Ma, Ying-Yu; Xia, Ying-Jie; Li, Li; Zhang, Ru-Xuan; Jin, Tao; Zhao, Zhong-Kuo; Xu, Ji; Yu, Sheng; Wu, Fang; Wang, Si-Zhen; Jiao, Yu-Chen; Yan, Hai; Tao, Hou-Quan

2015-01-01

Background Several somatic mutation hotspots were recently identified in the TERT promoter region in human cancers. Large scale studies of these mutations in multiple tumor types are limited, in particular in Asian populations. This study aimed to: analyze TERT promoter mutations in multiple tumor types in a large Chinese patient cohort, investigate novel tumor types and assess the functional significance of the mutations. Methods TERT promoter mutation status was assessed by Sanger sequencing for 13 different tumor types and 799 tumor tissues from Chinese cancer patients. Thymic epithelial tumors, gastrointestinal leiomyoma, and gastric schwannoma were included, for which the TERT promoter has not been previously sequenced. Functional studies included TERT expression by RT-qPCR, telomerase activity by the TRAP assay, and promoter activity by the luciferase reporter assay. Results TERT promoter mutations were highly frequent in glioblastoma (83.9%), urothelial carcinoma (64.5%), oligodendroglioma (70.0%), medulloblastoma (33.3%), and hepatocellular carcinoma (31.4%). C228T and C250T were the most common mutations. In urothelial carcinoma, several novel rare mutations were identified. TERT promoter mutations were absent in GIST, thymic epithelial tumors, gastrointestinal leiomyoma, gastric schwannoma, cholangiocarcinoma, gastric and pancreatic cancer. TERT promoter mutations highly correlated with upregulated TERT mRNA expression and telomerase activity in adult gliomas. These mutations differentially enhanced the transcriptional activity of the TERT core promoter. Conclusions TERT promoter mutations are frequent in multiple tumor types and have similar distributions in Chinese cancer patients. The functional significance of these mutations reflect the importance to telomere maintenance and hence tumorigenesis, making them potential therapeutic targets. PMID:25843513

In vitro and in vivo effect of 2,6-Di-tert-butyl-4-methylphenol as an antibiofilm agent against quorum sensing mediated biofilm formation of Vibrio spp.

Science.gov (United States)

Santhakumari, Sivasubramanian; Jayakumar, Rengarajan; Logalakshmi, Ravichandran; Prabhu, Narayanan Marimuthu; Abdul Nazar, Abdul Kuthus; Karutha Pandian, Shunmugiah; Veera Ravi, Arumugam

2018-05-25

This study unveils the in vitro and in vivo antibiofilm potential of 2,6-Di-tert-butyl-4-methylphenol (DTBMP) from Chroococcus turgidus against Vibrio spp. In the preliminary study, cell free culture supernatant (CFCS) of C. turgidus inhibited the violacein production in biomarker strain Chromobacterium violaceum and its mutant strain CV026 in a dose dependent manner. The effective biofilm inhibitory concentration (BIC) of pure compound DTBMP from C. turgidus was identified as 250 μg/ml concentration in tested Vibrio species. Furthermore, DTBMP proved to effectively inhibit the bioluminescence production in V. harveyi and other biofilm related virulence traits such as exopolysaccharides (EPS) production, hydrophobicity index, swimming and swarming motility at its BIC concentration in three major pathogenic vibrios: V. harveyi, V. parahaemolyticus and V. vulnificus. The antibiofilm potential of DTBMP was validated through light, confocal laser scanning and scanning electron microscopic analyses. In addition, the non-bactericidal effect of DTBMP was determined through growth curve and 2,3-bis (2-methyloxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) assay. Real-time PCR studies revealed the down-regulation of master quorum sensing (QS) regulator genes of V. harveyi such as luxR, luxS, luxP, luxQ and luxO on treatment with DTBMP. In vivo results confirmed that DTBMP augmented the survival rate of Litopenaeus vannamei larvae up to 75, 88 and 66% upon infection with V. harveyi, V. parahaemolyticus and V. vulnificus, respectively. The results of this study ascertain the promising effects of DTBMP as an antibiofilm agent, which could be positively explored to treat biofilm-associated vibrios infections in aquaculture. Copyright © 2018 Elsevier B.V. All rights reserved.

Estimating reaction rate constants from a two-step reaction: a comparison between two-way and three-way methods

NARCIS (Netherlands)

Bijlsma, S.; Smilde, A. K.

2000-01-01

In this paper, two different spectral datasets are used in order to estimate reaction rate constants using different algorithms. Dataset 1 consists of short-wavelength near-infrared (SW NIR) spectra taken in time of the two-step epoxidation of 2,5-di-tert-butyl-1,4-benzoquinone using tert-butyl

Optimized sampling of hydroperoxides and investigations of the water vapour dependence of hydroperoxide formation during ozonolysis of alkenes; Optimierung der Probenahme von Hydroperoxiden und Untersuchungen zur Wasserdampfabhaengigkeit der Bildung von Hydroperoxiden bei der Ozonolyse von Alkenen

Energy Technology Data Exchange (ETDEWEB)

Becker, K.H.; Plagens, H.

1997-06-01

There are several sampling methods for hydroperoxides none of which is particularly reliable. The authors therefore tested three new methods in order to optimize hydroperoxide sampling and, using the optimized sampling procedure, to investigate the water vapour dependence of hydroperoxide formation during ozonolysis of alkenes. (orig.) [Deutsch] Fuer die Probenahme von Hydroperoxiden existieren verschiedene Verfahren, von denen bisher keines als besonders zuverlaessig angesehen werden konnte. Daher wurden in dieser Arbeit drei Verfahren getestet, um die Probenahme von Hydroperoxiden zu optimieren und mit dem entsprechenden Verfahren die Wasserdampfabhaengigkeit der Bildung von Hydroperoxiden bei der Ozonolyse von Alkenen zu untersuchen. (orig.)

Product analyses and kinetic studies on gas phase oxidation of the fuel additive ethyl tert-butyl ether and its products; Produktanalysen und Kinetikuntersuchungen der Gasphasenoxidation des Kraftstoffadditivs Ethyl-tert-butylether und seiner Produkte

Energy Technology Data Exchange (ETDEWEB)

Becker, K H; Thuener, L

1997-04-01

The widespread use of the additive ETBE in gasoline leads to an increased release of this compound into the atmosphere via evaporation or exhaust fumes. In order to determine the influence of this additive on trace gas cycles it is first necessary to carry out studies on the degradation mechanisms and pertinent kinetic properties of this substance. The aim of the present study was to examine the degradation mechanisms of the fuel additive t-butyl ethyl ether under atmospheric conditions. The reactions of the main degradation products (t-butyl formiate and t-butyl acetate, together ca. 80%) were also studied in order to obtain as complete a picture of the degradation paths as possible. This was to permit an assessment of the influence of ETBE and its products on tropospheric trace gas cycles and ozone formation. [Deutsch] Bei haeufigem Zusatz von ETBE in Benzin wird diese Verbindung durch Verdampfung oder als Abgas verstaerkt in die Atmosphaere abgegeben. Um den Einfluss des Additivs auf die Spurengas-Kreislaeufe zu bestimmen, sind daher Untersuchungen noetig, um die Abbau-Mechanismen und die zugehoerigen kinetischen Daten zu ermitteln. Das Ziel dieser Arbeit ist die Untersuchung der Abbaumechanismen des Kraftstoffadditivs t-Butylethylether unter atmosphaerischen Bedingungen. Fuer eine moeglichst vollstaendige Analyse des Abbauweges werden auch die Reaktionen der Hauptabbauprodukte (t-Butylformiat und t-Butylacetat, zusammen etwa 80%) untersucht. Dadurch soll der Einfluss auf troposphaerische Spurengas-Kreislaeufe und auf die Ozonbildung von ETBE und seinen Produkten abgeschaetzt werden. (orig./SR)

TSA-induced DNMT1 down-regulation represses hTERT expression via recruiting CTCF into demethylated core promoter region of hTERT in HCT116.

Science.gov (United States)

Choi, Jee-Hye; Min, Na Young; Park, Jina; Kim, Jin Hong; Park, Soo Hyun; Ko, Young Jong; Kang, Yoonsung; Moon, Young Joon; Rhee, Sangmyung; Ham, Seung Wook; Park, Ae Ja; Lee, Kwang-Ho

2010-01-01

Trichostatin A (TSA), an inhibitor of histone deacetylase, is a well-known antitumor agent that effectively and selectively induces tumor growth arrest and apoptosis. Recently, it was reported that hTERT is one of the primary targets for TSA-induced apoptosis in cancer cells but the mechanism of which has not yet been elucidated. In the present study, to better understand the epigenetic regulation mechanism responsible for the repression of hTERT by TSA, we examined expression of hTERT in the HCT116 colon cancer cell line after treatment with TSA and performed site-specific CpG methylation analysis of the hTERT promoter. We found that TSA-induced the demethylation of site-specific CpGs on the promoter of hTERT, which was caused by down-regulation of DNA methyltransferase 1 (DNMT1). Among the demethylated region, the 31st-33rd CpGs contained a binding site for CTCF, an inhibitor of hTERT transcription. ChIP analysis revealed that TSA-induced demethylation of the 31st-33rd CpGs promoted CTCF binding on hTERT promoter, leading to repression of hTERT. Taken together, down-regulation of DNMT1 by TSA caused demethylation of a CTCF binding site on the hTERT promoter, the result of which was repression of hTERT via recruitment of CTCF to the promoter. Copyright 2009 Elsevier Inc. All rights reserved.

The thermal degradation of poly(iso-butyl methacrylate and poly(sec-butyl methacrylate

Directory of Open Access Journals (Sweden)

IVANKA G. POPOVIC

2000-12-01

Full Text Available The non-oxidative thermal degradation of poly(iso-butyl methacrylate and poly(sec-butyl methacrylate was investigated by studying changes in the polymer residue. Due to the different number of b-hydrogens in their ester substituents, these two polymeric isomers behave differently when subjected to elevated temperatures. Poly(iso-butyl methacrylate degrades quantitatively by depolymerisation with zip lengths of the same order of magnitude as those of poly(methyl methacrylate. Poly(sec-butyl methacrylate degrades by a combined degradation mechanism of depolymerisation and de-esterification. De-esterification becomes a significant thermolysis route at temperatures higher than 240°C.

Atmospheric hydrogen peroxide and organic hydroperoxides during PRIDE-PRD'06, China: their concentration, formation mechanism and contribution to secondary aerosols

Science.gov (United States)

Hua, W.; Chen, Z. M.; Jie, C. Y.; Kondo, Y.; Hofzumahaus, A.; Takegawa, N.; Chang, C. C.; Lu, K. D.; Miyazaki, Y.; Kita, K.; Wang, H. L.; Zhang, Y. H.; Hu, M.

2008-11-01

Atmospheric hydrogen peroxide (H2O2) and organic hydroperoxides were measured from 18 to 30 July in 2006 during the PRIDE-PRD'06 campaign at Backgarden, a rural site located 48 km north of Guangzhou, a mega-city in southern China. A ground-based instrument was used as a scrubbing coil collector to sample ambient air, followed by on-site analysis by high-performance liquid chromatography (HPLC) coupled with post-column derivatization and fluorescence detection. The H2O2 mixing ratio over the 13 days ranged from below the detection limit to a maximum of 4.6 ppbv, with a mean (and standard deviation) of (1.26±1.24) ppbv during the daytime (08:00 20:00 LT). Methyl hydroperoxide (MHP), with a maximum of 0.8 ppbv and a mean (and standard deviation) of (0.28±0.10) ppbv during the daytime, was the dominant organic hydroperoxide. Other organic peroxides, including bis-hydroxymethyl hydroperoxide (BHMP), peroxyacetic acid (PAA), hydroxymethyl hydroperoxide (HMHP), 1-hydroxy-ethyl hydroperoxide (1-HEHP) and ethyl hydroperoxide (EHP), were detected occasionally. The concentration of H2O2 exhibited a pronounced diurnal variation on sunny days, with a peak mixing ratio in the afternoon (12:00 18:00 LT), but lacked an explicit diurnal cycle on cloudy days. Sometimes a second peak mixing ratio of H2O2 was observed during the evening, suggesting that H2O2 was produced by the ozonolysis of alkenes. The diurnal variation profile of MHP was, in general, consistent with that of H2O2. The estimation indicated that in the morning the H2O2 detected was formed mostly through local photochemical activity, with the rest probably attributable to vertical transport. It is notable that relatively high levels of H2O2 and MHP were found in polluted air. The unexpectedly high level of HO2 radicals detected in this region can account for the production of hydroperoxides, while the moderate level of NOx suppressed the formation of hydroperoxides. High concentrations of hydroperoxides were detected

Epigallocatechin-3-Gallate Protects Erythrocyte Ca2+-ATPase and Na+/K+-ATPase Against Oxidative Induced Damage During Aging in Humans

Directory of Open Access Journals (Sweden)

Prabhanshu Kumar

2014-10-01

Full Text Available Purpose: The main purpose of this study was to investigate the protective role of epigallocatechin-3-gallate on tertiary butyl hydroperoxide induced oxidative damage in erythrocyte during aging in humans. Methods: Human erythrocyte membrane bound Ca2+-ATPase and Na+/K+-ATPase activities were determined as a function of human age. Protective role of epigallocatechin-3-gallate was evaluated by in vitro experiments by adding epigallocatechin-3-gallate in concentration dependent manner (final concentration range 10-7M to 10-4M to the enzyme assay medium. Oxidative stress was induced in vitro by incubating washed erythrocyte ghosts with tertiary butyl hydroperoxide (10-5 M final concentration. Results: We have reported concentration dependent effect of epigallocatechin-3-gallate on tertiary butyl hydroperoxide induced damage on activities of Ca2+-ATPase and Na+/K+-ATPase during aging in humans. We have detected a significant (p < 0.001 decreased activity of Ca2+-ATPase and Na+/K+ -ATPase as a function of human age. Epigallocatechin-3-gallate protected ATPases against tertiary butyl hydroperoxide induced damage in concentration dependent manner during aging in humans. Conclusion: Epigallocatechin-3-gallate is a powerful antioxidant that is capable of protecting erythrocyte Ca2+-ATPase and Na+/K+ -ATPase against oxidative stress during aging in humans. We may propose hypothesis that a high intake of catechin rich diet may provide some protection against development of aging and age related diseases.

Synthesis & Characterization of New bis-Symmetrical Adipoyl ...

African Journals Online (AJOL)

Full Title: Synthesis and Characterization of New bis-Symmetrical Adipoyl, Terepthaloyl, Chiral Diimido-di-L-alanine Diesters and Chiral Phthaloyl-L-alanine Ester of Tripropoxy p-tert-Butyl Calix[4]arene and Study of Their Hosting Ability for Alanine and Na+. Bis-symmetrical tripropoxy p-tert-butyl calix[4]arene esters were ...

Comparison of the effects of tert-butyl hydroperoxide and peroxynitrite on the oxidative damage to isolated beef heart mitochondria

Czech Academy of Sciences Publication Activity Database

Kohutiar, Matej; Ivica, Josko; Vytášek, R.; Skoumalová, A.; Illner, Jan; Šantorová, P.; Wilhelm, Jiří

2016-01-01

Roč. 65, č. 4 (2016), s. 617-626 ISSN 0862-8408 R&D Projects: GA ČR(CZ) GAP303/11/0298 Institutional support: RVO:67985823 Keywords : oxidative stress * free radicals * lipid peroxidation * lipofuscinlike pigments * nitrotyrosine Subject RIV: ED - Physiology Impact factor: 1.461, year: 2016

Isotope effects and the temperature dependences of the hyperfine coupling constants of muoniated sec-butyl radicals in condensed phases.

Science.gov (United States)

Fleming, Donald G; Bridges, Michael D; Arseneau, Donald J; Chen, Ya Kun; Wang, Yan Alexander

2011-04-07

Reported here is the first μSR study of the muon (A(μ)) and proton (A(p)) β-hyperfine coupling constants (Hfcc) of muoniated sec-butyl radicals, formed by muonium (Mu) addition to 1-butene and to cis- and trans-2-butene. The data are compared with in vacuo spin-unrestricted MP2 and hybrid DFT/B3YLP calculations reported in the previous paper (I), which played an important part in the interpretation of the data. The T-dependences of both the (reduced) muon, A(μ)′(T), and proton, A(p)(T), Hfcc are surprisingly well explained by a simple model, in which the calculated Hfcc from paper I at energy minima of 0 and near ±120° are thermally averaged, assuming an energy dependence given by a basic 2-fold torsional potential. Fitted torsional barriers to A(μ)′(T) from this model are similar (~3 kJ/mol) for all muoniated butyl radicals, suggesting that these are dominated by ZPE effects arising from the C−Mu bond, but for A(p)(T) exhibit wide variations depending on environment. For the cis- and trans-2-butyl radicals formed from 2-butene, A(μ)′(T) exhibits clear discontinuities at bulk butene melting points, evidence for molecular interactions enhancing these muon Hfcc in the environment of the solid state, similar to that found in earlier reports for muoniated tert-butyl. In contrast, for Mu−sec-butyl formed from 1-butene, there is no such discontinuity. The muon hfcc for the trans-2-butyl radical are seemingly very well predicted by B3LYP calculations in the solid phase, but for sec-butyl from 1-butene, showing the absence of further interactions, much better agreement is found with the MP2 calculations across the whole temperature range. Examples of large proton Hfcc near 0 K are also reported, due to eclipsed C−H bonds, in like manner to C−Mu, which then also exhibit clear discontinuities in A(p)(T) at bulk melting points. The data suggest that the good agreement found between theory and experiment from the B3LYP calculations for eclipsed bonds in

Natural and synthetic antioxidants: Influence on the oxidative stability of biodiesel synthesized from non-edible oil

Energy Technology Data Exchange (ETDEWEB)

Sarin, Amit [Department of Applied Sciences, Amritsar College of Engineering and Technology, Manawala, Amritsar-143001, Punjab (India); Singh, N.P. [Punjab Technical University, Jalandhar (India); Sarin, Rakesh; Malhotra, R.K. [Indian Oil Corporation Ltd., R and D Centre, Sector-13, Faridabad-121007 (India)

2010-12-15

According to the proposed National Mission on Biodiesel in India, we have undertaken studies on the oxidative stability of biodiesel synthesized from tree borne non-edible oil seeds jatropha. Neat jatropha biodiesel exhibited oxidation stability of 3.95 h and research was conducted to investigate the influence of natural and synthetic antioxidants on the oxidation stability of jatropha methyl ester. Antioxidants namely {alpha}-tocopherol, tert-butylated hydroxytoluene, tert-butylated phenol derivative, octylated butylated diphenyl amine, and tert-butylhydroxquinone were doped to improve the oxidation stability. It was found that both types of antioxidants showed beneficial effects in increasing the oxidation stability of jatropha methyl ester, but comparatively, the synthetic antioxidants were found to be more effective. (author)

Immunogenicity of the hTERT540-548 peptide in cancer

DEFF Research Database (Denmark)

Wenandy, L.; Sorensen, R.B.; Sengelov, L.

2008-01-01

Human telomerase reverse transcriptase (hTERT), the catalytic subunit of telomerase, is an attractive target antigen for cancer immunotherapy due to its expression in the vast majority of human tumors. The first immunogenic peptide described from hTERT was the HLA-A2-restricted peptide hTERT540...... in a peptide-specific, HLA-A2-restricted fashion. Furthermore, it was described that vaccination of cancer patients with hTERT540 introduced functional antitumor CD8(+) Tcells in patients. More recently, it was described that most patients with cancer have circulating hTERT540-specific CD8(+) T lymphocytes....... In contrast, several other studies have concluded that hTERT540 is not presented on the surface of tumor cells and that immunization of cancer patients with hTERT540 leads to the introduction of specificTcells that do not recognize tumor cells in vivo. In the present commentary, we summarize these highly...

Crystal structure of a supramolecular lithium complex of p-tert-butylcalix[4]arene

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Manabu Yamada

2018-05-01

Full Text Available Crystals of a supramolecular lithium complex with a calix[4]arene derivative, namely tetramethanollithium 5,11,17,23-tetra-tert-butyl-25,26,27-trihydroxy-28-oxidocalix[4]arene methanol monosolvate, [Li(CH3OH4](C44H55O4·CH3OH or [Li(CH3OH4]+·(calix[4]arene−]·CH3OH (where calix[4]arene− represents a mono-anion species because of deprotonation of one H atom of the calixarene hydroxy groups, were obtained from p-tert-butylcalix[4]arene reacted with LiH in tetrahydrofuran, followed by recrystallization from methanol. The asymmetric unit comprises one mono-anionic calixarene molecule, one Li+ cation coordinated to four methanol molecules, and one methanol molecule included in the calixarene cavity. The calixarene molecule maintains a cone conformation by intramolecular hydrogen bonding between one phenoxide (–O− and three pendent calixarene hydroxy groups (–OH. The coordinated methanol molecules around the metal cation play a significant role in forming the supramolecular assembly. The crystal structure of this assembly is stabilized by three sets of intermolecular interactions: (i hydrogen bonds involving the –OH and –O− moieties of the calixarene molecules, the –OH groups of the coordinated methanol molecules, and the –OH group of the methanol molecule included in the calixarene cavity; (ii C—H...π interactions between the calixarene molecules and/or the coordinated methanol molecules; (iii O—H...π interactions between the calixarene molecule and the included methanol molecule.

Three-dimensional structure of the ligand-binding core of GluR2 in complex with the agonist (S)-ATPA

DEFF Research Database (Denmark)

Lunn, Marie-Louise; Hogner, Anders; Stensbøl, Tine B

2003-01-01

Two X-ray structures of the GluR2 ligand-binding core in complex with (S)-2-amino-3-(5-tert-butyl-3-hydroxy-4-isoxazolyl)propionic acid ((S)-ATPA) have been determined with and without Zn(2+) ions. (S)-ATPA induces a domain closure of ca. 21 degrees compared to the apo form. The tert-butyl moiety...

Reaction of singlet-excited 2,3-diazabicyclo[2.2.2]oct-2-ene and tert-butoxyl radicals with aryl-substituted benzofuranones.

Science.gov (United States)

Lundgren, Cecilia Vannesjö; Koner, Apurba L; Tinkl, Michael; Pischel, Uwe; Nau, Werner M

2006-03-03

5,7-Di-tert-butyl-3-aryl-3H-benzofuran-2-ones are lactones with potential antioxidant activity, owing to their abstractable benzylic C-H hydrogens. The fluorescence quenching of the azoalkane 2,3-diazabicyclo[2.2.2]oct-2-ene (DBO), an established probe for the hydrogen-donor propensity of chain-breaking antioxidants, was investigated for 16 aryl-substituted benzofuranone derivatives [m,m-(CF3)2, p-CN, m-CN, p-CF3, p-COOCH3, m-CF3, p-Cl, p-F, H, m-CH3, p-CH3, m,p-(CH3)2, p-OCH3, o-CH3, o-CF3, o,m-(CH3)2]. Analysis of the rate data in terms of a linear free energy relationship yielded a reaction constant of rho = +0.35. This implies that n,pi*-excited DBO acts as nucleophilic species. In contrast, hydrogen abstraction of tert-butoxyl radicals from the benzofuranones was accelerated by electron-donating substituents (rho = -0.23), in conformity with the electrophilic character of oxygen-centered alkoxyl radicals. Possible implications for the optimization of the hydrogen-donor propensity of antioxidants through structural variation are discussed.

In vivo oxidative stress alters thiol redox status of peroxiredoxin 1 and 6 and impairs rat sperm quality

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Yannan Liu

2017-01-01

Full Text Available Oxidative stress, the imbalance between the production of reactive oxygen species (ROS and antioxidant activity is a major culprit of male infertility. Peroxiredoxins (PRDXs are major antioxidant enzymes of mammalian spermatozoa and are thiol oxidized and inactivated by ROS in a dose-dependent manner. Their deficiency and/or inactivation have been associated with men infertility. The aim of this study was to elucidate the impact of oxidative stress, generated by the in vivo tert-butyl hydroperoxide (tert-BHP treatment on rat epididymal spermatozoa during their maturation process. Adult Sprague-Dawley males were treated with 300 μmoles tert-BHP/kg or saline (control per day intraperitoneal for 15 days. Lipid peroxidation (2-thibarbituric acid reactive substances assay, total amount and thiol oxidation of PRDXs along with the total amount of superoxide dismutase (SOD, motility and DNA oxidation (8-hydroxy-deoxyguanosine were determined in epididymal spermatozoa. Total amount of PRDXs and catalase and thiol oxidation of PRDXs were determined in caput and cauda epididymis. While animals were not affected by treatment, their epididymal spermatozoa have decreased motility, increased levels of DNA oxidation and lipid peroxidation along with increased PRDXs (and not SOD amounts. Moreover, sperm PRDXs were highly thiol oxidized. There was a differential regulation in the expression of PRDX1 and PRDX6 in the epididymis that suggests a segment-specific role for PRDXs. In conclusion, PRDXs are increased in epididymal spermatozoa in an attempt to fight against the oxidative stress generated by tert-BHP in the epididymis. These findings highlight the role of PRDXs in the protection of sperm function and DNA integrity during epididymal maturation.

P. berghei telomerase subunit TERT is essential for parasite survival.

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Agnieszka A Religa

Full Text Available Telomeres define the ends of chromosomes protecting eukaryotic cells from chromosome instability and eventual cell death. The complex regulation of telomeres involves various proteins including telomerase, which is a specialized ribonucleoprotein responsible for telomere maintenance. Telomeres of chromosomes of malaria parasites are kept at a constant length during blood stage proliferation. The 7-bp telomere repeat sequence is universal across different Plasmodium species (GGGTTT/CA, though the average telomere length varies. The catalytic subunit of telomerase, telomerase reverse transcriptase (TERT, is present in all sequenced Plasmodium species and is approximately three times larger than other eukaryotic TERTs. The Plasmodium RNA component of TERT has recently been identified in silico. A strategy to delete the gene encoding TERT via double cross-over (DXO homologous recombination was undertaken to study the telomerase function in P. berghei. Expression of both TERT and the RNA component (TR in P. berghei blood stages was analysed by Western blotting and Northern analysis. Average telomere length was measured in several Plasmodium species using Telomere Restriction Fragment (TRF analysis. TERT and TR were detected in blood stages and an average telomere length of ∼ 950 bp established. Deletion of the tert gene was performed using standard transfection methodologies and we show the presence of tert- mutants in the transfected parasite populations. Cloning of tert- mutants has been attempted multiple times without success. Thorough analysis of the transfected parasite populations and the parasite obtained from extensive parasite cloning from these populations provide evidence for a so called delayed death phenotype as observed in different organisms lacking TERT. The findings indicate that TERT is essential for P. berghei cell survival. The study extends our current knowledge on telomere biology in malaria parasites and validates further

Two-year drinking water carcinogenicity study of methyl tertiary-butyl ether (MTBE) in Wistar rats.

Science.gov (United States)

Dodd, Darol; Willson, Gabrielle; Parkinson, Horace; Bermudez, Edilberto

2013-07-01

Methyl tertiary-butyl ether (MTBE) has been used as a gasoline additive to reduce tailpipe emissions and its use has been discontinued. There remains a concern that drinking water sources have been contaminated with MTBE. A two-year drinking water carcinogenicity study of MTBE was conducted in Wistar rats (males, 0, 0.5, 3, 7.5 mg ml(-1); and females, 0, 0.5, 3, and 15 mg ml(-1)). Body weights were unaffected and water consumption was reduced in MTBE-exposed males and females. Wet weights of male kidneys were increased at the end of two years of exposure to 7.5 mg ml(-1) MTBE. Chronic progressive nephropathy was observed in males and females, was more severe in males, and was exacerbated in the high MTBE exposure groups. Brain was the only tissue with a statistically significant finding of neoplasms. One astrocytoma (1/50) was found in a female rat (15 mg ml(-1)). The incidence of brain astrocytomas in male rats was 1/50, 1/50, 1/50 and 4/50 for the 0, 0.5, 3 and 7.5 mg ml(-1) exposure groups, respectively. This was a marginally significant statistical trend, but not statistically significant when pairwise comparisons were made or when multiple comparisons were taken into account. The incidence of astrocytoma fell within historical control ranges for Wistar rats, and the brain has not been identified as a target organ following chronic administration of MTBE, ethyl tert-butyl ether, or tertiary butyl alcohol (in drinking water) to mice and rats. We conclude that the astrocytomas observed in this study are not associated with exposure to MTBE. Copyright © 2011 John Wiley & Sons, Ltd.

Identification and characterization of N-tert-butoxycarbonyl-MDMA: a new MDMA precursor.

Science.gov (United States)

Collins, Michael; Donnelly, Christopher; Cameron, Shane; Tahtouh, Mark; Salouros, Helen

2017-03-01

In September 2015, 80 litres of a viscous, light-red liquid, described as hair product, was seized by the Australian Border Force (ABF). Initial testing by ABF indicated that the liquid was the 3,4-methylenedioxymethamphetamine (MDMA) precursor chemical safrole and custody of the material was transferred to the Australian Federal Police (AFP) who coordinated all subsequent investigations. Initial gas chromatography-mass spectrometry (GC-MS) analysis by the AFP indicated that the material was not safrole and samples of the liquid were transferred to the National Measurement Institute Australia (NMIA) for identification. Using a combination of nuclear magnetic resonance spectroscopy (NMR), GC-MS, infrared spectroscopy, and synthesis, the unknown substance was identified as N-tert.-butoxycarbonyl-MDMA (t-BOC-MDMA). The substance was also converted in high yield to MDMA (aqueous HCl, 80 °C, 30 min). The possibility that the t-BOC-MDMA may act as a pro-drug following ingestion was explored by exposure to simulated gastric juice (pH 1.5) and monitored by NMR (37 °C) at various intervals. The majority of t-BOC-MDMA was converted to MDMA after 305 min, which suggested that this derivatized form might serve as a pro-drug in vivo. An investigation into the chemistry of potential pro-drugs showed that t-BOC derivatives of methamphetamine, pseudoephedrine and 4-methylmethcahtinone (mephedrone) could also be prepared using di-tert.-butyl dicarbonate. The appearance of t-BOC-derivatives on the drug market requires further monitoring. © 2016 Commonwealth of Australia. Drug Testing and Analysis © 2016 John Wiley & Sons, Ltd. © 2016 Commonwealth of Australia. Drug Testing and Analysis © 2016 John Wiley & Sons, Ltd.

Determination of the extractive capacity of para-tert butyl calix[8]arene octa-phosphinoylated towards uranyl ions from an aqueous-acidic-salty medium

International Nuclear Information System (INIS)

Serrano V, E. C.

2011-01-01

The extraction properties of octa-phosphinoylated para-tert butyl calix[8]arene (prepared in the laboratory) in chloroform towards uranyl ions from an aqueous-acidic-salty medium (HNO 3 -3.5 NaNO 3 ) containing uranyl nitrate salt, was investigated. Two spectroscopic techniques UV/Vis and Luminescence were used for this study. The latter permitted analyze the fluorescence from the uranyl ions influenced by the surrounding medium. Both permitted to learn about the power of this calixarene as extractant towards the mentioned ions. Its extraction ability or capability using this calixarene at 5.91 x 10 -4 M towards the uranyl ions was 400% as determined by UV/Vis while fluorescence revealed 100% of uranyl ion extraction. A closed analysis of the results obtained by using these techniques revealed that the stoichiometry of the main extracted species was 1calixarene:2 uranyl ions. The loading capacity of the calixarene ligand towards the uranyl ions was also investigated using both techniques. UV/Vis resulted to be inadequate for quantifying exactly the loading capacity of the calixarene whereas luminescence was excellent indeed, using a 5.91 x 10 -4 M calixarene concentration, its loading capacity was 0.157 M of free uranyl ions from 0.161 M of uranyl ions present in the aqueous-acidic-salty medium. The extracts from the ability and capacity studies were concentrated to dryness, purified and the dried extracts were analyzed by infrared and neutron activation analysis. By these techniques it was demonstrated that during the extraction of the uranyl ions by the calixarene ligand they form thermodynamically and kinetically stable complexes, since in the solid state, the 1:2, calixarene; uranyl ions stoichiometry was kept with the minimum formula: (UO 2 ) 2 B 8 bL 8 (NO 3 ) 4 (H 2 O) 4 CHCl 3 (CH 3 OH) 3 the methanol molecules come from its purification. It is proposed that B 8 bL 8 calixarene in chloroform medium is a good extractant for the treatment of nuclear wastes or

μ-Carbonato-κ4 O,O′:O′,O′′-bis­{[2′-(di-tert-butyl­phosphan­yl)biphenyl-2-yl-κ2 P,C 1]palladium(II)} dichloro­methane monosolvate

Science.gov (United States)

Muller, Alfred; Holzapfel, Cedric W.

2012-01-01

The title compound, [(μ2-CO3){Pd(P(t-C4H9)2(C12H8)}2]·CH2Cl2, the first CO3-bridged palladium dimer complex reported to date, was obtained while preparing the Pd0 complex with (2-biphen­yl)P(tBu)2. In the crystal, each palladium dimer is accompanied by a dichloro­methane solvent mol­ecule. Coordination of the carbonate and chelated phosphane ligands gives distorted square-planar environments at the Pd atoms. Important geometrical parameters include Pd—P(av.) = 2.2135 (4) Å, Pd—C(av.) = 1.9648 (16) Å and P—Pd—C = 84.05 (5) and 87.98 (5)°, and O—Pd—O′ = 60.56 (4) and 61.13 (4)°. Bonding with the carbonate O atoms shows values of 2.1616 (11) and 2.1452 (11) Å for the Pd—O—Pd bridge, whereas other Pd—O distances are slightly longer at 2.2136 (11) and 2.1946 (11) Å. One of the tert-butyl groups is disordered over two set of sites with an occupancy ratio of 0.723 (6):0.277 (6). Weak C—H⋯O interactions are observed propagating the molecules along the [100] direction. PMID:23468771

Epoxidation of cyclohexene by ethyl-benzene hydroperoxide in the presence of molybdenum catalyst

International Nuclear Information System (INIS)

Sapunov, V.N.; Litvintsev, I.Yu.; Margitfal'vi, J.; Lebedev, N.N.

1977-01-01

A study has been made of the kinetic experimental pattern and mechanism of epoxidation of cyclohexene by ethylbenzene hydroperoxide during catalysis by Mo(CO) 6 in various solvents. A first order of reaction with respect to the catalyst and complex order of reaction with respect to the hydroperoxide and olefine have been established. Simple (square and cross) inhibition by reaction products, cyclohexene oxide and methylphenylcarbinol, have been found. An increase in the dielectric constant of the solvent diminishes the epoxidation rate. The mechanism scheme of the process is proposed and main kinetic parameters calculated

Serum paraoxonase activity and lipid hydroperoxide levels in adult ...

African Journals Online (AJOL)

EB

2013-09-03

Sep 3, 2013 ... Objectives: In this study, we aimed to investigate serum PON1 activity and lipid hydroperoxide (LOOH) levels in adult football players after three days ... oxidative stress after three days football tournament. In addition, physical activity for a ... polymorphism, gender, and exercise. Furthermore, it has been ...

Development of an online analyzer of atmospheric H 2O 2 and several organic hydroperoxides for field campaigns

Science.gov (United States)

François, S.; Sowka, I.; Monod, A.; Temime-Roussel, B.; Laugier, J. M.; Wortham, H.

2005-03-01

An online automated instrument was developed for atmospheric measurements of hydroperoxides with separation and quantification of H 2O 2 and several organic hydroperoxides. Samples were trapped in aqueous solutions in a scrubbing glass coil. Analyses were performed on an HPLC column followed by para-hydroxyphenylacetic acid (POPHA) acetic acid and peroxidase derivatization and fluorescence detection. Analytical and sampling tests were performed on different parameters to obtain optimum signal-to-noise ratios, high resolution and collection efficiencies higher than 95% for H 2O 2 and organic hydroperoxides. The obtained performances show large improvements compared to previous studies. The sampling and analytical devices can be coupled providing an online analyzer. The device was used during two field campaigns in the Marseilles area in June 2001 (offline analyzer) and in July 2002 (online analyzer) at rural sites at low and high altitudes, respectively, during the ESCOMPTE and BOND campaigns. During the ESCOMPTE campaign, H 2O 2 was detected occasionally, and no organic hydroperoxides was observed. During the BOND campaign, substantial amounts of H 2O 2 and 1-HEHP+MHP were often detected, and two other organic hydroperoxides were occasionally detected. These observations are discussed.

Comparison of wet-chemical methods for determination of lipid hydroperoxides

DEFF Research Database (Denmark)

Nielsen, Nina Skall; Timm Heinrich, Maike; Jacobsen, Charlotte

2003-01-01

Five methods for determination of lipid hydroperoxides were evaluated, including two iodometric procedures involving a titration and a spectrophotometric micro method, and three other spectrophotometric methods namely the ferro, International Dairy Federation (IDF) and FOX2 (ferrous oxidation...... in xylenol orange). Peroxide values determined in a range of food products by these five methods gave different results. The ferro method required large amounts of solvent (50 mL/sample); the FOX2 method had a low range (0.005-0.04 mumol hydroperoxide); the end point detection of the titration method...... was subjective and required a large amount of sample (1 g); and the micro method was sensitive to interruptions during execution. Therefore, only the modified IDF method was chosen for further testing and validation. Stability tests of the standard curve showed a variation coefficient of 4% and within runs...

Hepatoprotective Effect of Terminalia chebula against t-BHP-Induced Acute Liver Injury in C57/BL6 Mice

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Min-Kyung Choi

2015-01-01

Full Text Available We aimed to identify the hepatoprotective effects of Terminalia chebula water extract (TCW and its corresponding pharmacological actions using C57/BL6 mice model of tert-butylhydroperoxide-(t-BHP- induced acute liver injury. Mice were orally administered with TCW (0, 50, 100, or 200 mg/kg or gallic acid (100 mg/kg for 5 days before t-BHP (2.5 mM/kg injection. Liver enzymes, histopathology, oxidative stress parameters, antioxidant components, and inflammatory cytokines were examined 18 h after t-BHP injection. t-BHP injection caused dramatic elevation of serum AST, ALT, and LDH level, while TCW pretreatment notably attenuated these elevations. Inflammatory cytokines including TNF-α, IL-1β, and IL-6 were notably increased in hepatic tissues, and then these were efficiently attenuated by TCW pretreatment. t-BHP injection notably increased malondialdehyde, total reactive oxygen species, and nitric oxide in the liver tissue, while it markedly dropped the antioxidant activities including total antioxidant capacity, total glutathione contents, glutathione peroxidase, superoxide dismutase, and catalase. TCW pretreatment remarkably ameliorated these alterations, and these effects were relevant to gene expressions. Histopathological examinations supported the above findings. Collectively, these findings well prove that TCW beneficially prevents acute and severe liver injury and clarify its corresponding mechanisms involved in the inhibition of oxidative stress and inflammatory cytokines.

Synthesis and electrochemical properties of a new benzimidazole derivative as the acceptor unit in donor–acceptor–donor type polymers

International Nuclear Information System (INIS)

Ozelcaglayan, Ali Can; Sendur, Merve; Akbasoglu, Naime; Apaydin, Dogukan Hazar; Cirpan, Ali; Toppare, Levent

2012-01-01

A new benzimidazole unit, 4′-(tert-butyl)spiro[benzo[d]imidazole-2,1′-cyclohexane] was synthesized and coupled with different donor units like 3-hexylthiophene and 3,4-ethylenedioxythiophene (EDOT) via Stille coupling. The donor–acceptor–donor (D–A–D) type monomers, 4′-(tert-butyl)-4,7-bis(4-hexylthiophen-2-yl) spiro[benzo[d]imidazole-2,1′-cyclohexane] (BIHT) and 4′-(tert-butyl)-4,7-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl) spiro[benzo[d]imidazole-2,1′-cyclohexane] (BIED) were electrochemically polymerized, their electrochemical and optical properties were investigated by cyclic voltammetry, UV–vis-NIR spectroscopy techniques. Effect of donor groups on the optical and electronic properties of polymer was studied.

Chelating agent-free, vapor-assisted crystallization method to synthesize hierarchical microporous/mesoporous MIL-125 (Ti).

Science.gov (United States)

McNamara, Nicholas D; Hicks, Jason C

2015-03-11

Titanium-based microporous heterogeneous catalysts are widely studied but are often limited by the accessibility of reactants to active sites. Metal-organic frameworks (MOFs), such as MIL-125 (Ti), exhibit enhanced surface areas due to their high intrinsic microporosity, but the pore diameters of most microporous MOFs are often too small to allow for the diffusion of larger reactants (>7 Å) relevant to petroleum and biomass upgrading. In this work, hierarchical microporous MIL-125 exhibiting significantly enhanced interparticle mesoporosity was synthesized using a chelating-free, vapor-assisted crystallization method. The resulting hierarchical MOF was examined as an active catalyst for the oxidation of dibenzothiophene (DBT) with tert-butyl hydroperoxide and outperformed the solely microporous analogue. This was attributed to greater access of the substrate to surface active sites, as the pores in the microporous analogues were of inadequate size to accommodate DBT. Moreover, thiophene adsorption studies suggested the mesoporous MOF contained larger amounts of unsaturated metal sites that could enhance the observed catalytic activity.

The Protection of Hepatocyte Cells from the Effects of Oxidative Stress by Treatment with Vitamin E in Conjunction with DTT

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Jen-Hsiang Tsai

2010-01-01

Full Text Available We investigated the effect of vitamin E on membrane protein thiols under oxidative stress, which we induced by treating hepatocytes with tert-butyl hydroperoxide (TBH for 60 mins. Those cells which we pretreated with vitamin E formed fewer blebs (22.3% compared to 60.0% in nonvitamin E-treated cells and maintained cytosolic calcium concentration and the number of membrane protein thiols instead of showing the usual symptoms in cells undergoing oxidative stress. Dithiothreitol (DTT also commonly reduces bleb formation in hepatocytes affected by TBH. However, our experiments clearly demonstrate that DTT does not prevent the changes in cytosolic calcium and membrane protein thiols in the blebbing cells. Consequently, we decided to pretreat cells with both DTT and vitamin E and found that the influence of TBH was entirely prevented. These findings may provide us with a new aspect for investigating the mechanism of bleb formation under oxidative stress.

The synthesis and spectroscopic study of stable free radicals related to piperidine-n-oxyl, including a stable bi-radical

International Nuclear Information System (INIS)

Briere, R.

1965-07-01

A new synthesis of di-tert-butyl nitroxide using the reaction between tert-butyl magnesium chloride and nitro-tert-butane is presented in the first section. Synthesis and investigation of stable free piperidine-N-oxyl radicals are described in the second section. All these nitroxides have been characterised by their I. R., U. V. and E. P. R. absorption spectra. The final section contains a description of the synthesis of a stable bi-radical of the nitroxide type by condensation of 2,2, 6, 6-tetramethyl-piperid-4-one-l-oxyl with hydrazine. (author) [fr

Atmospheric hydrogen peroxide and organic hydroperoxides during PRIDE-PRD'06, China: their concentration, formation mechanism and contribution to secondary aerosols

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W. Hua

2008-11-01

Full Text Available Atmospheric hydrogen peroxide (H₂O₂ and organic hydroperoxides were measured from 18 to 30 July in 2006 during the PRIDE-PRD'06 campaign at Backgarden, a rural site located 48 km north of Guangzhou, a mega-city in southern China. A ground-based instrument was used as a scrubbing coil collector to sample ambient air, followed by on-site analysis by high-performance liquid chromatography (HPLC coupled with post-column derivatization and fluorescence detection. The H₂O₂ mixing ratio over the 13 days ranged from below the detection limit to a maximum of 4.6 ppbv, with a mean (and standard deviation of (1.26±1.24 ppbv during the daytime (08:00–20:00 LT. Methyl hydroperoxide (MHP, with a maximum of 0.8 ppbv and a mean (and standard deviation of (0.28±0.10 ppbv during the daytime, was the dominant organic hydroperoxide. Other organic peroxides, including bis-hydroxymethyl hydroperoxide (BHMP, peroxyacetic acid (PAA, hydroxymethyl hydroperoxide (HMHP, 1-hydroxy-ethyl hydroperoxide (1-HEHP and ethyl hydroperoxide (EHP, were detected occasionally. The concentration of H₂O₂ exhibited a pronounced diurnal variation on sunny days, with a peak mixing ratio in the afternoon (12:00–18:00 LT, but lacked an explicit diurnal cycle on cloudy days. Sometimes a second peak mixing ratio of H₂O₂ was observed during the evening, suggesting that H₂O₂ was produced by the ozonolysis of alkenes. The diurnal variation profile of MHP was, in general, consistent with that of H₂O₂. The estimation indicated that in the morning the H₂O₂ detected was formed mostly through local photochemical activity, with the rest probably attributable to vertical transport. It is notable that relatively high levels of H₂O₂ and MHP were found in polluted air. The unexpectedly high level of HO₂ radicals

``Living polymers'' in organic solvents : stress relaxation in bicopper tetracarboxylate/tert-butyl cyclohexane solutions

Science.gov (United States)

Terech, P.; Maldivi, P.; Dammer, C.

1994-10-01

Viscoelastic solutions of a bicopper tetracarboxylate complex in tert-butylcyclohexane have been studied by dynamic rheology in a wide range of concentrations (0.5-1.5 % volume fraction). The zero shear viscosity, the elastic modulus, the terminal stress relaxation time and the height of the high-frequency dip, in a Cole-Cole representation of the complex elastic modulus, follow scaling laws. The related exponents are discussed in the context of the physics of “living polymers” : a term used to describe worm-like species undergoing scission/recombination reactions competing mainly with the reptation motions of the chains. The current system, made up of molecular threads (17.5 Å diameter) of Cu2(O2C-CH(C2H5)C4H9)4 in the apolar solvent, is representative of a “living polymer” where, instead of mechanisms involving transient star polymeric crosslinks, a reversible scission mechanism prevails. The dynamics in the high-frequency range evolves from a regime where reptation is the dominant relaxation mechanism to a cross-over regime where “breathing” fluctuations and Rouse motions become important. Large modifications of the stress relaxation function occur for more concentrated systems. The binary system is the first example of a “living polymer” in an organic solvent and exhibits elastic moduli (G ≈ ca. 120 Pa à φ = 1 %) which are at least 20 times larger than those found for the aqueous “living polymer” systems. Les solutions viscoélastiques d'un tétracarboxylate binucléaire de cuivre dans le tert-butylcyclohexane sont étudiées par rhéologie en mode dynamique dans une gamme étendue de concentrations (0,5 %-15,5 %). La viscosité à gradient nul, le module élastique, le temps terminal de relaxation et la hauteur du puits à haute fréquence, dans une représentation Cole-Cole du module élastique complexe, suivent des lois d'échelles. Les exposants correspondants sont discutés dans le contexte de la physique des “polymères vivants

Substituted Pyrazinecarboxamides: Synthesis and Biological Evaluation

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Katarina Kralova

2006-03-01

Full Text Available Condensation of the corresponding chlorides of some substituted pyrazine-2-carboxylic acids (pyrazine-2-carboxylic acid, 6-chloropyrazine-2-carboxylic acid, 5-tert-butylpyrazine-2-carboxylic acid or 5-tert-butyl-6-chloropyrazine-2-carboxylic acid withvarious ring-substituted aminothiazoles or anilines yielded a series of amides. Thesyntheses, analytical and spectroscopic data of thirty newly prepared compounds arepresented. Structure-activity relationships between the chemical structures and the anti-mycobacterial, antifungal and photosynthesis-inhibiting activity of the evaluatedcompounds are discussed. 3,5-Bromo-4-hydroxyphenyl derivatives of substitutedpyrazinecarboxylic acid, 16-18, have shown the highest activity against Mycobacteriumtuberculosis H37Rv (54-72% inhibition. The highest antifungal effect againstTrichophyton mentagrophytes, the most susceptible fungal strain tested, was found for5-tert-butyl-6-chloro-N-(4-methyl-1,3-thiazol-2-ylpyrazine-2-carboxamide (8, MIC =31.25 μmol·mL-1. The most active inhibitors of oxygen evolution rate in spinachMolecules 2006, 11 243 chloroplasts were the compounds 5-tert-butyl-6-chloro-N-(5-bromo-2-hydroxyphenyl- pyrazine-2-carboxamide (27, IC50 = 41.9 μmol·L-1 and 5-tert-butyl-6-chloro-N-(1,3- thiazol-2-yl-pyrazine-2-carboxamide (4, IC50 = 49.5 μmol·L-1.

Intermolecular Hydrogen Transfer in Isobutane Hydrate

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Takeshi Sugahara

2012-05-01

Full Text Available Electron spin resonance (ESR spectra of butyl radicals induced with γ-ray irradiation in the simple isobutane (2-methylpropane hydrate (prepared with deuterated water were investigated. Isothermal annealing results of the γ-ray-irradiated isobutane hydrate reveal that the isobutyl radical in a large cage withdraws a hydrogen atom from the isobutane molecule through shared hexagonal-faces of adjacent large cages. During this “hydrogen picking” process, the isobutyl radical is apparently transformed into a tert-butyl radical, while the sum of isobutyl and tert-butyl radicals remains constant. The apparent transformation from isobutyl to tert-butyl radicals is an irreversible first-order reaction and the activation energy was estimated to be 35 ± 3 kJ/mol, which was in agreement with the activation energy (39 ± 5 kJ/mol of hydrogen picking in the γ-ray-irradiated propane hydrate with deuterated water.

The genome-wide early temporal response of Saccharomyces cerevisiae to oxidative stress induced by cumene hydroperoxide.

Directory of Open Access Journals (Sweden)

Wei Sha

Full Text Available Oxidative stress is a well-known biological process that occurs in all respiring cells and is involved in pathophysiological processes such as aging and apoptosis. Oxidative stress agents include peroxides such as hydrogen peroxide, cumene hydroperoxide, and linoleic acid hydroperoxide, the thiol oxidant diamide, and menadione, a generator of superoxide, amongst others. The present study analyzed the early temporal genome-wide transcriptional response of Saccharomyces cerevisiae to oxidative stress induced by the aromatic peroxide cumene hydroperoxide. The accurate dataset obtained, supported by the use of temporal controls, biological replicates and well controlled growth conditions, provided a detailed picture of the early dynamics of the process. We identified a set of genes previously not implicated in the oxidative stress response, including several transcriptional regulators showing a fast transient response, suggesting a coordinated process in the transcriptional reprogramming. We discuss the role of the glutathione, thioredoxin and reactive oxygen species-removing systems, the proteasome and the pentose phosphate pathway. A data-driven clustering of the expression patterns identified one specific cluster that mostly consisted of genes known to be regulated by the Yap1p and Skn7p transcription factors, emphasizing their mediator role in the transcriptional response to oxidants. Comparison of our results with data reported for hydrogen peroxide identified 664 genes that specifically respond to cumene hydroperoxide, suggesting distinct transcriptional responses to these two peroxides. Genes up-regulated only by cumene hydroperoxide are mainly related to the cell membrane and cell wall, and proteolysis process, while those down-regulated only by this aromatic peroxide are involved in mitochondrial function.

Rearrangement of Upstream Sequences of the hTERT Gene During Cellular Immortalization

Science.gov (United States)

Zhao, Yuanjun; Wang, Shuwen; Popova, Evgenya Y.; Grigoryev, Sergei A.; Zhu, Jiyue

2010-01-01

Telomerase expression, resulting from transcriptional activation of the hTERT gene, allows cells to acquire indefinite proliferative potential during cellular immortalization and tumorigenesis. However, mechanisms of hTERT gene activation in many immortal cell lines and cancer cells are poorly understood. Here, we report our studies on hTERT activation using genetically related pairs of telomerase-negative (Tel−) and -positive (Tel+) fibroblast lines. First, whereas transiently transfected plasmid reporters did not recapitulate the endogenous hTERT promoter, the promoter in chromosomally integrated bacterial artificial chromosome (BAC) reporters was activated in a subset of Tel+ cells, indicating that activation of the hTERT promoter required native chromatin context and/or distal regulatory elements. Second, the hTERT gene, located near the telomere of chromosome 5p, was translocated in all three Tel+ cell lines but not in their parental pre-crisis cells and Tel− immortal siblings. The breakage points were mapped to regions upstream of the hTERT promoter, indicating that the hTERT gene was the target of these chromosomal rearrangements. In two Tel+ cell lines, translocation of the endogenous hTERT gene appeared to be the major mechanism of its activation as the activity of hTERT promoter in many chromosomally integrated BAC reporters, with intact upstream and downstream neighboring loci, remained relatively low. Therefore, our results suggest that rearrangement of upstream sequences is an important new mechanism of hTERT promoter activation during cellular immortalization. The chromosomal rearrangements likely occurred during cellular crisis and facilitated by telomere dysfunction. Such translocations allowed the hTERT promoter to escape from the native condensed chromatin environment. PMID:19672873

Selective epoxidation of allylic alcohols with a titania-silica aerogel

Energy Technology Data Exchange (ETDEWEB)

Dusi, M.; Mallat, T.; Baiker, A. [Lab. of Technical Chemistry, Swiss Federal Inst. of Technology, ETH-Zentrum, Zuerich (Switzerland)

1998-12-31

An amorphous mesoporous titania-silica aerogel (20 wt%TiO{sub 2} - 80 wt% SiO{sub 2}) and tert.-butylhydroperoxide (TBHP) have been used for the epoxidation of various allylic alcohols. Allylic alcohols possessing an internal double bond were more reactive than those with a terminal C=C bond. Epoxide selectivities could be improved by addition of (basic) zeolite 4 A and NaHCO{sub 3} to the reaction mixture. (orig.)

Environmentally Compliant Vinyl Ester Resin (VER) Composite Matrix Resin Derived from Renewable Resources

Science.gov (United States)

2011-11-01

polycar- bonate and polyacrylate thermoplastic resins. Annual production of phenol in the United States (Dow) exceeds 650 million pounds with virtually...second method reacted glycidol with methyl methacrylate in the presence of 2, 4- dimethyl-6-tert.butyl phenol and potassium cyanide [24]. The mixture...presence of DCC and the second reacted glycidol with methyl methacrylate in the presence of potassium cyanide and 2, 4-dimethyl-6-tert.butyl phenol

Exploring the Reactivity of Thiocarbonyl S-(tert-Alkylimides)

DEFF Research Database (Denmark)

El-Essawy, Farag A. G.; Khattab, Ahmed F.; Yassin, Salah M.

1999-01-01

Three new alfa-oxo thione S-(tert-alkylimides) 3 have been prepared. Thiocarbonyl S- (tert-alkylimides) react with chlorine and bromine, but not with other halogens or pseudohalogens, to give the corresponding dihalomethylene compounds. The pyrolysis of 3 leads to the corresponding 1,2,4-trithiol...

Compound list: butylated hydroxyanisole [Open TG-GATEs

Lifescience Database Archive (English)

Full Text Available butylated hydroxyanisole BHA 00156 ftp://ftp.biosciencedbc.jp/archive/open-tggates/...LATEST/Human/in_vitro/butylated_hydroxyanisole.Human.in_vitro.Liver.zip ftp://ftp.biosciencedbc.jp/archive/o...pen-tggates/LATEST/Rat/in_vivo/Liver/Single/butylated_hydroxyanisole.Rat.in_vivo.Liver.Single.zip ftp://ftp....biosciencedbc.jp/archive/open-tggates/LATEST/Rat/in_vivo/Liver/Repeat/butylated_hydroxyanisole.Rat.in_vivo.Liver.Repeat.zip ...

tert-Butyl 2-(4-nitrophenoxyacetate

Directory of Open Access Journals (Sweden)

Qamar Ali

2011-02-01

Full Text Available In the title molecule, C12H15NO5, the nitrophenoxy portion is approximately planar (r.m.s. deviation = 0.034 Å and makes an angle of 84.8 (1° with respect to the –CH2–C(=O–O–C fragment. In the crystal, π–π stacking is observed between nearly parallel benzene rings of adjacent molecules, the centroid–centroid distance being 3.6806 (10 Å. Weak intermolecular C—H...O hydrogen bonding is present in the crystal structure.

Advances towards aromatic oligoamide foldamers

DEFF Research Database (Denmark)

Hjelmgaard, Thomas; Plesner, Malene; Dissing, Mette Marie

2014-01-01

We have efficiently synthesized 36 arylopeptoid dimers with ortho-, meta-, and para-substituted aromatic backbones and tert-butyl or phenyl side chains. The dimers were synthesized by using a "submonomer method" on solid phase, by applying a simplified common set of reaction conditions. X......-ray crystallographic analysis of two of these dimers disclosed that the tert-butyl side chain invokes a cis amide conformation with a comparatively more closely packed structure of the surrounding aromatic backbone while the phenyl side chain results in a trans amide conformation with a more open, extended structure...... of the surrounding aromatic backbone. Investigation of the X-ray structures of two arylopeptoid dimers disclosed that the tert-butyl side chain invokes a cis amide conformation with a closely packed structure of the surrounding aromatic backbone while the phenyl side chain results in a trans amide conformation...

Substituted Amides of Pyrazine-2-carboxylic acids: Synthesis and Biological Activity

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Katarina Kralova

2002-03-01

Full Text Available Condensation of 6-chloro-, 5-tert-butyl- or 6-chloro-5-tert-butylpyrazine-2-carboxylic acid chloride with ring substituted anilines yielded a series of amides, which were tested for their in vitro antimycobacterial, antifungal and photosynthesis-inhibiting activities. The highest antituberculotic activity (72% inhibition against Mycobacterium tuberculosis and the highest lipophilicity (log P = 6.85 were shown by the 3,5-bistrifluoromethylphenyl amide of 5-tert-butyl-6-chloropyrazine-2-carboxylic acid (2o. The 3-methylphenyl amides of 6-chloro- and 5-tert-butyl-6-chloro-pyrazine-2-carboxylic acid (2d and 2f exhibited only a poor in vitro antifungal effect (MIC = 31.25-500 μmol·dm-3 against all strains tested, although the latter was the most active antialgal compound (IC50 = 0.063 mmol·dm-3. The most active inhibitor of oxygen evolution rate in spinach chloroplasts was the (3,5-bis-trifluoromethylphenylamide of 6-chloropyrazine-2-carboxylic acid (2m, IC50 = 0.026 mmol·dm-3.

Synthesis and solution self-assembly of side-chain cobaltocenium-containing block copolymers.

Science.gov (United States)

Ren, Lixia; Hardy, Christopher G; Tang, Chuanbing

2010-07-07

The synthesis of side-chain cobaltocenium-containing block copolymers and their self-assembly in solution was studied. Highly pure monocarboxycobaltocenium was prepared and subsequently attached to side chains of poly(tert-butyl acrylate)-block-poly(2-hydroxyethyl acrylate), yielding poly(tert-butyl acrylate)-block-poly(2-acryloyloxyethyl cobaltoceniumcarboxylate). The cobaltocenium block copolymers exhibited vesicle morphology in the mixture of acetone and water, while micelles of nanotubes were formed in the mixture of acetone and chloroform.

Isotope-dilution gas chromatography-mass spectrometry coupled with injection-port butylation for the determination of 4-t-octylphenol, 4-nonylphenols and bisphenol A in human urine.

Science.gov (United States)

Chung, Shuang-Hung; Ding, Wang-Hsien

2018-02-05

An analytical method that utilizes isotope-dilution gas chromatography-mass spectrometry (ID-GC-MS) coupled with injection-port butylation was developed. The method was validated, and confirmed to be able to determine the presence of three commonly detected endocrine-disrupting chemicals (EDCs: 4-tert-octylphenol (4-t-OP), 4-nonylphenols (4-NPs) and bisphenol A (BPA)) in human urine with high precision and accuracy. After sample preparation by solid-phase extraction, the extract was introduced into GC-MS via injection-port butylation. The butylated target analytes were identified and quantified by using ion-trap mass spectrometry operating in the selected-ion-storage mode, and employing the measurement of peak area ratios of the butylated target analytes and labeled-analogues in the samples and calibration standards. The labeled-analogues were also used to correct the variations associated with the analysis and matrix effect. The limits of quantitation (LOQs) ranged from 0.1 to 0.3ng/mL. High precisions for both intra- and inter-day analysis ranged from 1 to 6%, and excellent accuracy (mean recovery) ranged from 92 to 105% on two concentration levels. In human urine, the total concentrations of three selected EDCs varied from 1.28 to 7.14ng/mL. 4-NPs were detected within all collected samples. The developed method allows accurate analysis of trace-level of EDCs in urine, and these target EDCs could act as useful biomarkers to assess exposure in biomonitoring studies and programs. Copyright © 2017 Elsevier B.V. All rights reserved.

Radiosynthesis of [18F]fluorophenyl-L-amino acids by isotopic exchange on carbonyl-activated precursors

International Nuclear Information System (INIS)

Castillo Melean, Johnny

2011-01-01

Aromatic [ 18 F]fluoroamino acids have earlier been developed as promising probes for diagnostics using PET. However, a wider use of these radiofluorinated compounds has been limited due to radiosynthetic constraints. The work here presents an amenable three-step radiosynthesis pathway for the preparation of 2-[ 18 F]fluoro-L-phenylalanine (2-[ 18 F]Fphe), 2-[ 18 F]fluoro-L-tyrosine (2-[ 18 F]Ftyr), 6-[ 18 F]fuoro-L-m-tyrosine (6-[ 18 F]Fmtyr) and 6-[ 18 F]fluoro-L-DOPA (6-[ 18 F]FDOPA). For this, corresponding precursors were 18 F-fluorinated by nucleophilic isotopic exchange, followed by either removal of an activating formyl group with Rh(PPh 3 ) 3 Cl or its conversion by Baeyer-Villiger oxidation, respectively, and subsequent hydrolysis of protecting groups in acidic medium. Two efficient synthetic approaches were developed for the preparation of highly functionalized fluoro-benzaldehydes and -ketones which were used as labeling precursors. The compounds (2S,5S)-tert-butyl 2-tert-butyl-5-(2-fluoro-5-formylbenzyl)-3-methyl-4-oxoimidazolidine-1 -carboxylate (1a), (2S,5S)-tert-butyl 5-(5-acetyl-2-fluorobenzyl)-2-tert-butyl-3-methyl-4-oxoimidazolidine-1 -carboxylate (1c), (2S,5S)-benzyl 2-tert-butyl-5-(2-fluoro-5-formylbenzyl)-3-methyl-4-oxoimidazolidine-1 -carbo-xylate (1d), 4-fluoro-3-(((2S,5R)-5-isopropyl-3,6-dimethoxy-2,5-dihydropyrazin-2-yl) me-thyl)b enzal-dehyde (1e) and 1-(4-fluoro-3-(((2S,5R)-5-isopropyl-3,6-dimethoxy-2,5-dihydropyrazin-2-yl) me-thy l)phenyl)ethanone (1f), could be prepared in six steps and overall yields of 41%, 48%, 37%, 27%, and 32%, respectively. (2S,5S)-tert-Butyl 5-(4-(benzyloxy)-2-fluoro-5-formylbenzyl)-2-tert-butyl-3-methyl-4 -oxoimidazolidi ne-1-carboxylate (1b) was prepared in ten steps with an overall yield of 19% while compounds (2S,5S)-tert-butyl 5-(5-(3,5-bis(trifluoromethyl)-benzoyl)-2-fluorobenzyl)-2-tert-butyl-3 -methyl-4-oxoimidazolidine-1-carboxylate (1g) and (2S,5S)-tert-butyl 2-tert-butyl-5-(2-fluoro-5

Mn(III)-initiated facile oxygenation of heterocyclic 1,3-dicarbonyl compounds.

Science.gov (United States)

Rahman, Md Taifur; Haque, Md Aminul; Igarashi, Hikaru; Nishino, Hiroshi

2011-11-16

The Mn(III)-initiated aerobic oxidation of heterocyclic 1,3-dicarbonyl compounds, such as 4-alkyl-1,2-diphenylpyrazolidine-3,5-diones, 1,3-dialkylpyrrolidine-2,4-diones, 3-alkyl-1,5-dimethylbarbituric acids, and 3-butyl-4-hydroxy-2-quinolinone gave excellent to good yields of the corresponding hydroperoxides, which were gradually degraded by exposure to the metal initiator after the reaction to afford the corresponding alcohols. The synthesis of 30 heterocyclic 1,3-dicarbonyl compounds, the corresponding hydroperoxides and the 10 alcohols, their characterization, and the limitations of the procedure are described. In addition, the mechanism of the hydroperoxidation and the redox decomposition of the hydroperoxides are discussed.

Radiochemical study of isomerization of free butyl cations

International Nuclear Information System (INIS)

Sinotova, E.N.; Nefedov, V.D.; Skorokhodov, S.S.; Arkhipov, Yu.M.

1987-01-01

Ion-molecular reactions of free butyl cations, generated by nuclear chemical method, with carbon monoxide containing small quantities of ethanol vapors are studied. Carbon monoxide was used to fix instable butyl cations in the form of corresponding acyl ions. Ester of α-methyl-butyric acid appears to be the only product of free butyl cation interaction with carbon monoxide in the presence of ethanol vapors. That means, that up to the moment of butyl cation reaction with carbon monoxide, the primary butyl cations are almost completely isomerized into secondary in agreement with results of previous investigations. This allows one to study free butyl cation isomerization process according to ion-molecular reaction product isomeric composition

Study of 2-methyl -2-oxo-3,5-di-tert.-butyl-Δ4-1,3,2-oxazaphospholine interaction with lanthanide shifting reagents

International Nuclear Information System (INIS)

Turov, A.V.; Povolotskij, M.I.; Balitskij, Yu.V.; Kornilov, M.Yu.; Boldeskul, I.E.

1983-01-01

2-methyl-2-oxo-3.5-di-tret.-butyl-Δ 4 -1, 3, 2-oxazaphospholine in CDCl 3 solution reacts with lanthanide shifting reagents-tris (dipivaloylmethanates) of europium (3) and praseodymium (3)-with the formation of adducts of constant composition. At that, in ( + H, 13 C) NMR spectra considerable pseudocontact induced shifts of substratum signals take place. Geometry of the adducts formed is calculated

Alkylation of 2,6-di-tert-butylphenol with methyl acrylate catalyzed by potassium-2,6-di-tert-butylphenoxide

OpenAIRE

Zaikov, Gennady; Volod’kin, Alexander

2010-01-01

The kinetics of catalytic alkylation of 2,6-ditert- butylphenol (ArOH) with methyl acrylate (MA) in the presence of potassium 2,6-di-tert-butylphenoxide (ArOK) depends on the method for the preparation of ArOK. The reaction ofArOH withKOHat temperatures > 453 Kaffords monomeric ArOK, which properties differ from those in the case of potassium 2,6-di-tert-butylphenoxide synthesized by the earliermethods.The regularities ofArOH alkylation depend ontheArOKconcentration, theArOH...

Synthesis of deuterium-labeled analogs of the lipid hydroperoxide-derived bifunctional electrophile 4-oxo-2(E)-nonenal

OpenAIRE

Arora, Jasbir S.; Oe, Tomoyuki; Blair, Ian A.

2011-01-01

Lipid hydroperoxides undergo homolytic decomposition into the bifunctional 4-hydroxy-2(E)-nonenal and 4-oxo-2(E)-nonenal (ONE). These bifunctional electrophiles are highly reactive and can readily modify intracellular molecules including glutathione (GSH), deoxyribonucleic acid (DNA) and proteins. Lipid hydroperoxide-derived bifunctional electrophiles are thought to contribute to the pathogenesis of a number of diseases. ONE is an α,β-unsaturated aldehyde that can react in multiple ways and w...

Bis[O,O′-bis(4-tert-butylphenyl dithiophosphato-κ2S,S′]bis(pyridine-κNlead(II

Directory of Open Access Journals (Sweden)

Xiulan Zhang

2013-09-01

Full Text Available In the title compound, [Pb(C20H26O2PS22(C5H5N2], the PbII ion is coordinated by two S,S′-bidentate anions and two pyridine molecules. The PbN2S4 coordination geometry approximates to a pentagonal bipyramid with one equatorial site vacant. The N atoms occupy the axial sites. One of the pyridine molecules is disordered over two sets of sites in a 0.907 (7:0.093 (7 ratio and one of the tert-butyl groups is disordered over two sets of sites in a 0.534 (6:0.466 (6 ratio. An intramolecular C—H...O interaction occurs in one of the ligands. In the crystal, pairs of short Pb...S contacts [3.4018 (11 Å] generate a centrosymmetric dimeric assembly with the distant S atom lying in the region of the vacant coordination site of the metal atom. No directional packing interactions occur.

Quantum mechanical study and spectroscopic (FT-IR, FT-Raman, UV-Visible) study, potential energy surface scan, Fukui function analysis and HOMO-LUMO analysis of 3-tert-butyl-4-methoxyphenol by DFT methods.

Science.gov (United States)

Saravanan, S; Balachandran, V

2014-09-15

This study represents an integral approach towards understanding the electronic and structural aspects of 3-tert-butyl-4-methoxyphenol (TBMP). Fourier-transform Infrared (FT-IR) and Fourier-transform Raman (FT-Raman) spectra of TBMP was recorded in the region 4000-400 cm(-1) and 3500-100 cm(-1), respectively. The molecular structures, vibrational wavenumbers, infrared intensities and Raman activities were calculated using DFT (B3LYP and LSDA) methods using 6-311++G (d,p) basis set. The most stable conformer of TBMP was identified from the computational results. The assignments of vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) following the scaled quantum mechanical force field (SQMFF) methodology. The first order hyperpolarizability (β0) and related properties (β, α0 and Δα) of TBMP have been discussed. The stability and charge delocalization of the molecule was studied by Natural Bond Orbital (NBO) analysis. UV-Visible spectrum and effects of solvents have been discussed and the electronic properties such as HOMO and LUMO energies were determined by time-dependent TD-DFT approach with B3LYP/6-311++G (d,p) level of theory. The molecule orbital contributions are studied by density of energy states (DOSs). The reactivity sites are identified by mapping the electron density into electrostatic potential surface (MEP). Mulliken analysis of atomic charges is also calculated. The thermodynamic properties at different temperatures were calculated, revealing the correlations between standard heat capacities, standard entropy and standard enthalpy changes with temperatures. Global hardness, global softness, global electrophilicity and ionization potential of the title compound are determined. Copyright © 2014 Elsevier B.V. All rights reserved.

Development of Targeted Nanobubbles for Ultrasound Imaging and Ablation of Metastatic Prostate Cancer Lesions

Science.gov (United States)

2015-10-01

synthesized as anthracene functional poly(tert-butyl acrylate )-Br (Anth-PtBA-Br) which not only carries the functionality for DA “click” reaction...hydrophilic poly( acrylic acid) (PAA) from PtBA by simply hydrolysis of tert-butyl groups using trifluoroacetic acid (TFA). In order to investigate the...inside a degassed water tank at 37 o C (Figure 5, Panel A). A high- speed, 1 megapixel CCD camera (Phantom V210, Vision Research) was positioned to

Proteome alteration induced by hTERT transfection of human fibroblast cells.

Science.gov (United States)

Mazzucchelli, Gabriel D; Gabelica, Valérie; Smargiasso, Nicolas; Fléron, Maximilien; Ashimwe, Wilson; Rosu, Frédéric; De Pauw-Gillet, Marie-Claire; Riou, Jean-François; De Pauw, Edwin

2008-04-17

Telomerase confers cellular immortality by elongating telomeres, thereby circumventing the Hayflick limit. Extended-life-span cells have been generated by transfection with the human telomerase reverse transcriptase (hTERT) gene. hTERT transfected cell lines may be of outstanding interest to monitor the effect of drugs targeting the telomerase activity. The incidence of hTERT gene transfection at the proteome level is a prerequisite to that purpose. The effect of the transfection has been studied on the proteome of human fibroblast (WI38). Cytosolic and nuclear fractions of WI38 cells, empty vector transfected WI38 (WI38-HPV) and hTERT WI38 cells were submitted to a 2D-DIGE (Two-Dimensional Differential In-Gel Electrophoresis) analysis. Only spots that had a similar abundance in WI38 and WI38-HPV, but were differentially expressed in WI38 hTERT were selected for MS identification. This method directly points to the proteins linked with the hTERT expression. Number of false positive differentially expressed proteins has been excluded by using control WI38-HPV cells. The proteome alteration induced by hTERT WI38 transfection should be taken into account in subsequent use of the cell line for anti-telomerase drugs evaluation. 2D-DIGE experiment shows that 57 spots out of 2246 are significantly differentially expressed in the cytosolic fraction due to hTERT transfection, and 38 were confidently identified. In the nuclear fraction, 44 spots out of 2172 were selected in the differential proteome analysis, and 14 were identified. The results show that, in addition to elongating telomeres, hTERT gene transfection has other physiological roles, among which an enhanced ER capacity and a potent cell protection against apoptosis. We show that the methodology reduces the complexity of the proteome analysis and highlights proteins implicated in other processes than telomere elongation. hTERT induced proteome changes suggest that telomerase expression enhances natural cell repair

Proteome alteration induced by hTERT transfection of human fibroblast cells

Directory of Open Access Journals (Sweden)

Riou Jean-François

2008-04-01

Full Text Available Abstract Background Telomerase confers cellular immortality by elongating telomeres, thereby circumventing the Hayflick limit. Extended-life-span cells have been generated by transfection with the human telomerase reverse transcriptase (hTERT gene. hTERT transfected cell lines may be of outstanding interest to monitor the effect of drugs targeting the telomerase activity. The incidence of hTERT gene transfection at the proteome level is a prerequisite to that purpose. The effect of the transfection has been studied on the proteome of human fibroblast (WI38. Cytosolic and nuclear fractions of WI38 cells, empty vector transfected WI38 (WI38-HPV and hTERT WI38 cells were submitted to a 2D-DIGE (Two-Dimensional Differential In-Gel Electrophoresis analysis. Only spots that had a similar abundance in WI38 and WI38-HPV, but were differentially expressed in WI38 hTERT were selected for MS identification. This method directly points to the proteins linked with the hTERT expression. Number of false positive differentially expressed proteins has been excluded by using control WI38-HPV cells. The proteome alteration induced by hTERT WI38 transfection should be taken into account in subsequent use of the cell line for anti-telomerase drugs evaluation. Results 2D-DIGE experiment shows that 57 spots out of 2246 are significantly differentially expressed in the cytosolic fraction due to hTERT transfection, and 38 were confidently identified. In the nuclear fraction, 44 spots out of 2172 were selected in the differential proteome analysis, and 14 were identified. The results show that, in addition to elongating telomeres, hTERT gene transfection has other physiological roles, among which an enhanced ER capacity and a potent cell protection against apoptosis. Conclusion We show that the methodology reduces the complexity of the proteome analysis and highlights proteins implicated in other processes than telomere elongation. hTERT induced proteome changes suggest

Oxygen radicals in experimental shock: effects of spin-trapping nitrones in ameliorating shock pathophysiology (see comments)

Energy Technology Data Exchange (ETDEWEB)

Novelli, G.P. (Institute of Anesthesiology and Intensive Care, University of Florence, Careggi Hospital, (Italy))

1992-04-01

Circulatory shock is accepted as a consequence of an acute oxygen radical overgeneration. Spin-trapping nitrones inactivate free radicals by forming relatively stable adducts. Three spin-trapping nitrones (N-tert-phenyl-butyl-nitrone; alpha-4-pyridyl-oxide-N-tert-butyl-nitrone; 5-5,dimethyl,1,pyrroline-N-oxide) were tested regarding their role in the pathophysiology and evolution of circulatory shock in rats. A prospective, randomized, controlled trial of spin-trapping nitrones in rats experiencing three different models of circulatory shock was designed. In the first group, endotoxic, traumatic, and mesenteric artery occlusion shock (all 100% lethal in control experiments) was prevented by the ip administration of N-tert-phenyl-butyl-nitrone (150 mg/kg); alpha-4-pyridyl-oxide-N-tert-butyl-nitrone (100 mg/kg); or 5-5,dimethyl,1,pyrroline-N-oxide (100 mg/kg). However, the evolution of shock was unaffected by the same compounds when all three nitrones had been previously inactivated by exposure to light and air. In the second group, microcirculatory derangements that were provoked by endotoxin and were observed in the mesocecum of rats were completely prevented by pretreatment with either peritoneal administration of each of the three nitrones or by their topical application to the microscopic field. While the rats survived after systemic treatment, those rats receiving topical nitrones died from endotoxic shock. In the third group, cell-membrane stiffness (a sign of peroxidative damage) was measured by spin-probes and electron-spin resonance in mitochondrial and microsomal membranes. Cell membranes obtained from shocked rats were more rigid than those membranes of controls. However, the membranes obtained from rats that were submitted to trauma or endotoxin after pretreatment with N-tert-phenyl-butyl-nitrone had normal stiffness.

Butyl Rubber: Compound Development and Characterization

National Research Council Canada - National Science Library

Sloan, James

2000-01-01

...), to develop the standard butyl rubber compound. The strategy of this work was to compound- and compression-mold high-quality, uniform butyl rubber experimental sheets and to evaluate their cure properties, mechanical properties...

The study of DNA adduct 8-hydroxy-2‧deoxyguanosine (8-OHdG) formation of butylated hydroxyanisole (BHA) and its metabolite ter-butyl hydroquinone (TBHQ) through in vitro reaction with Calf Thymus DNA and 2‧deoxyguanosine

Science.gov (United States)

Budiawan; Purwaningsih, S. S.; Cahaya, D. I.

2017-04-01

Butylated Hydroxyanisole (BHA) and its metabolite Tert-Butyl Hydroquinone (TBHQ) are synthetic antioxidants, commonly used as food and beverage preservatives. Although WHO declared their safety, the use of these preservatives are still controversial because some studies showed that BHA induced proliferative effects in animal testing and TBHQ is considered as carcinogenic and causes DNA cleavage. This study is aimed to analyze the interaction between Calf Thymus DNA with BHA and TBHQ which are mediated with Copper (II) Chloride. The result of the study in spectrophotometric showed there was bathochromic shift as much as 2-3 nm in DNA treated with TBHQ. The next analysis used HPLC method in stationary phase of ODS, mobile phase of 10mM Natrium Hydrogen Phosphate Buffer and Methanol (85 : 15) for DNA adduct formation, 8-Hydroxy-2-Deoxyguanosine (8-OHDG) as biomarker of risk cancer. The resultof the study showed the formation of DNA adduct 8-OHDG in the interaction between DNA and 20-500 ppm of TBHQ. The 8-OHdG formation was greatly increased by the higher concentration of TBHQ. The relative amount of 8 OHDG which formed was reached 946/105 deoxyguanosine in DNA bases. Confirmation test by LCMS/MS was characterized with the detection of mother ion peak (m/z 284); fragment ion peaks at m/z 167.9, and 139.9; at retention time 3.52 min. Meanwhile the interaction between DNA and 50-250 ppm BHA did not induce 8-OHDG.

Cell-mediated reduction of protein and peptide hydroperoxides to reactive free radicals

DEFF Research Database (Denmark)

Headlam, Henrietta A; Davies, Michael Jonathan

2003-01-01

Radical attack on proteins in the presence of O(2) gives protein hydroperoxides in high yields. These peroxides are decomposed by transition metal ions, reducing agents, UV light and heat, with the formation of a range of reactive radicals that are capable of initiating further damage. Evidence has...... been presented for the formation of alcohols as stable products of peroxide decomposition, and these have been employed as markers of oxidative damage in vivo. The mechanism of formation of these alcohols is unclear, with both radical and nonradical pathways capable of generating these products....... In this study we have investigated the reduction of peptide and protein hydroperoxides by THP-1 (human monocyte-like) cells and it is shown that this process is accompanied by radical formation as detected by EPR spin trapping. The radicals detected, which are similar to those detected from metal-ion catalyzed...

Mn(III-Initiated Facile Oxygenation of Heterocyclic 1,3-Dicarbonyl Compounds

Directory of Open Access Journals (Sweden)

Md. Aminul Haque

2011-11-01

Full Text Available The Mn(III-initiated aerobic oxidation of heterocyclic 1,3-dicarbonyl compounds, such as 4-alkyl-1,2-diphenylpyrazolidine-3,5-diones, 1,3-dialkylpyrrolidine-2,4-diones, 3-alkyl-1,5-dimethylbarbituric acids, and 3-butyl-4-hydroxy-2-quinolinone gave excellent to good yields of the corresponding hydroperoxides, which were gradually degraded by exposure to the metal initiator after the reaction to afford the corresponding alcohols. The synthesis of 30 heterocyclic 1,3-dicarbonyl compounds, the corresponding hydroperoxides and the 10 alcohols, their characterization, and the limitations of the procedure are described. In addition, the mechanism of the hydroperoxidation and the redox decomposition of the hydroperoxides are discussed.

hTERT promoter mediating gene therapy in laryngeal squamous carcinomas cells in vitro

International Nuclear Information System (INIS)

Liao Zhengkai; Zhou Yunfeng; Zhou Fuxiang; Luo Zhiguo; Xiong Jie; Bao Jie; Xie Conghua; Liu Shiquan

2007-01-01

Objective: To investigate the relationship among hTERT promoter activity, hTERT mRNA expression, and telomerase activity (TA) in laryngeal squamous carcinomas cell lines, and to evaluate the usefulness of hTERT promoter mediated gene therapy. Methods: After plasmids pGL3-hTERTp were transfected, hTEBT promoter activity, hTERT mRNA expression and TA were determined by luciferase assay, RT-PCR and TRAP-PCR-ELISA, respectively. Plasmid phTERTp-HRP was constructed and transfected, HRP expression was determined by RT-PCR and competent peroxidase activity was confirmed by enzyme activity assay. The cytotoxicity and radiosensitivity of phTERTp-HRP/IAA were determined by clonogenic assay. Results: The relative levels of hTERT promoter activity, hTERT mRNA expression and TA in Hep2R cells were 1.37-fold, 1.43-fold and 1.81-fold compared with Hep2R cells, hTERT promoter activity was closely associated with hTERT mRNA expression and TA levels (P SF 2 ) was 1.24 (Hep2R cells) and 1.20 (Hep 2cells), the parameter a of with or without IAA incubation were 0.090, 0.020 (Hep2R)and 0.099, 0.042 (Hep2). Conclusions: hTERT promoter is applicable in mediating gene therapy in different radiosensitive laryngeal squamous carcinomas cells. hTERTp-HRP/IAA gene therapy may be a promising supplementary method for radiotherapy of laryngeal squamous-cell carcinomas. (authors)

Study of hTERT and Histone 3 Mutations in Medulloblastoma.

Science.gov (United States)

Viana-Pereira, Marta; Almeida, Gisele Caravina; Stavale, João Norberto; Malheiro, Susana; Clara, Carlos; Lobo, Patrícia; Pimentel, José; Reis, Rui Manuel

2017-01-01

Hotspot activating mutations of the telomerase reverse transcriptase (hTERT) promoter region were recently described in several tumor types. These mutations lead to enhanced expression of telomerase, being responsible for telomere maintenance and allowing continuous cell division. Additionally, there are alternative telomere maintenance mechanisms, associated with histone H3 mutations, responsible for disrupting the histone code and affecting the regulation of transcription. Here, we investigated the clinical relevance of these mechanistically related molecules in medulloblastoma. Sixty-nine medulloblastomas, formalin fixed and paraffin embedded, from a cohort of patients aged 1.5-70 years, were used to investigate the hotspot mutations of the hTERT promoter region, i.e. H3F3A and HIST1H3B, using Sanger sequencing. We successfully sequenced hTERT in all 69 medulloblastoma samples and identified a total of 19 mutated cases (27.5%). c.-124:G>A and c.-146:G>A mutations were detected, respectively, in 16 and 3 samples. Similar to previous reports, hTERT mutations were more frequent in older patients (p < 0.0001), being found only in 5 patients <20 years of age. In addition, hTERT-mutated tumors were more frequently recurrent (p = 0.026) and hTERT mutations were significantly enriched in tumors located in the right cerebellar hemisphere (p = 0.039). No mutations were found on the H3F3A or HIST1H3B genes. hTERT promoter mutations are frequent in medulloblastoma and are associated with older patients, prone to recurrence and located in the right cerebellar hemisphere. On the other hand, histone 3 mutations do not seem to be present in medulloblastoma. © 2016 S. Karger AG, Basel.

TERT promoter mutations are highly recurrent in SHH subgroup medulloblastoma

NARCIS (Netherlands)

M. Remke (Marc); E.A. Ramaswamy; M. Peacock (Munro); D.J.H. Shih (David J.); C. Koelsche (Christian); P.A. Northcott (Paul A.); N. Hill (Nadia); S. Cavalli (Silvia); M. Kool (Marcel); X. Wang (Xin); S. Mack (Stephen); M. Barszczyk (Mark); A.S. Morrissy (A. Sorana); X. Wu (Xiaochong); S. Agnihotri (Sameer); P. Luu (Phan); D. Jones (David); L. Garzia (Livia); A.M. Dubuc (Adrian); N. Zhukova (Nataliya); R. Vanner (Robert); J.M. Kros (Johan); P.J. French (Pim); E.G. van Meir (Erwin); R. Vibhakar (Rajeev); K. Zitterbart (Karel); J.A. Chan (Jennifer); L. Bognár (László); A. Klekner (Almos); B. Lach (Boleslaw); S. Jung (Shin); F. Saad (Fred); L.M. Liau (Linda); S. Albrecht (Steffen); M. Zollo (Maurizio); M.K. Cooper (Michael); R.C. Thompson (Reid); O. Delattre (Olivier); F. Bourdeaut (Franck); F.F. Doz (François); M. Garami (Miklós); P. Hauser (Peter); C.G. Carlotti (Carlos); T.E. Van Meter (Timothy); L. Massimi (Luca); D. Fults (Daniel); L.W. Pomeroy (Laura); T. Kumabe (Toshiro); Y.S. Ra (Young Shin); J.R. Leonard (Jeffrey); S.K. Elbabaa (Samer); J. Mora (Jaume); J.B. Rubin (Joshua); Y.-J. Cho (Yoon-Jae); R.E. McLendon (Roger); D.D. Bigner (Darell); C.G. Eberhart (Charles); M. Fouladi (Maryam); R.J. Wechsler-Reya (Robert); R. Faria (Rui); S.E. Croul (Sidney); A. Huang (Anding); E. Bouffet (Eric); C.E. Hawkins (Cynthia); M. Dirks (Maaike); W.A. Weiss (William); U. Schüller (Ulrich); A. Pollack (Aaron); P. Rutkowski (Piotr); D. Meyronet (David); A. Jouvet (Anne); M. Fèvre-Montange (Michelle); N. Jabado (Nada); M. Perek-Polnik (Marta); W.A. Grajkowska (Wieslawa); S.-K. Kim (Seung-Ki); J.T. Rutka (James); E. Malkin (Elissa); U. Tabori (Uri); S.M. Pfister (Stefan); A. Korshunov (Andrey); A. von Deimling (Andreas); M.D. Taylor (Michael)

2013-01-01

textabstractTelomerase reverse transcriptase (TERT) promoter mutations were recently shown to drive telomerase activity in various cancer types, including medulloblastoma. However, the clinical and biological implications of TERT mutations in medulloblastoma have not been described. Hence, we sought

Real time monitoring and quantification of reactive oxygen species in breast cancer cell line MCF-7 by 2',7'-dichlorofluorescin diacetate (DCFDA) assay.

Science.gov (United States)

Figueroa, Daniela; Asaduzzaman, Mohammad; Young, Fiona

2018-04-07

The detection of reactive oxygen species (ROS) using 2',7'-dichlorofluorescin diacetate (DCFDA) is commonly performed by a single measurement of fluorescence but this fails to capture a profile of ROS generation over time. This study aimed to develop a real-time monitoring method to increase the utility of the assay, to incorporate cytotoxicity screening and to describe the combined effects of DCFDA and the ROS generator, Ter-butyl hydrogen peroxide (TBHP). Breast cancer MCF-7 cells were loaded with DCFDA (0-50 μM) for 45 min, and then exposed to TBHP (0-50 μM). Fluorescence was recorded according to three different schedules: every hour for 6 h, or once after 6 h or 24 h. Viability was assessed in a crystal violet assay and cell morphology was examined by microscopy. TBHP caused a time and dose-dependent increase in ROS and the magnitude of the fluorescent signal was affected by the loading concentration of DCFDA. Reading the fluorescence every hour for 6 h did not diminish the emission signal. The most sensitive and reliable combination for this ROS assay was 10 μM DCFDA with 25 μM TBHP; since higher concentrations of DCFDA compromised cell viability. In conclusion we adapted a single point ROS assay to enable production of a profile of ROS generation over an extended 6 h period, and related this to cell viability and morphology. Published by Elsevier Inc.

The Inhibitory Effects of Aqueous Extract from Guava Twigs, Psidium guajava L., on Mutation and Oxidative Damage

Directory of Open Access Journals (Sweden)

Zhi-Chyang Kang

2013-01-01

Full Text Available This study examines the inhibitory effects of the aqueous extract from guava twigs (GTE, Psidium guajava L., on mutation and oxidative damage. The results show that GTE inhibits the mutagenicity of 4-nitroquinoline-N-oxide (4-NQO, a direct mutagen, and 2-aminoanthracene (2-AA, an indirect mutagen, toward Salmonella typhimurium TA 98 and TA 100. In addition, GTE shows radical scavenging, reducing activities, tyrosinase inhibition, and liposome protection effects. Meanwhile, GTE in the range of 0.1–0.4 mg/mL protects liver cells from tert-butyl-hydroperoxide-(t-BHP- induced cytotoxicity. Furthermore, the cytotoxicity inhibition of GTE in the t-BHP-treated cells was demonstrated in a dose-dependent manner. High-performance liquid chromatography analysis suggests that the major phenolic constituents in GTE are gallic acid, ferulic acid, and myricetin. These active phenolic components may contribute to the biological protective effects of GTE in different models. The data suggest that GTE exhibiting biological activities can be applied to antimutation, antityrosinase, and antioxidative damage.

On the Use of Potential Denaturing Agents for Ethanol in Direct Ethanol Fuel Cells

Directory of Open Access Journals (Sweden)

Domnik Bayer

2011-01-01

Full Text Available Acidic or alkaline direct ethanol fuel cells (DEFCs can be a sustainable alternative for power generation if they are fuelled with bio-ethanol. However, in order to keep the fuel cheap, ethanol has to be exempted from tax on spirits by denaturing. In this investigation the potential denaturing agents fusel oil, tert-butyl ethyl ether, and Bitrex were tested with regard to their compatibility with fuel cells. Experiments were carried out both in sulphuric acid and potassium hydroxide solution. Beside, basic electrochemical tests, differential electrochemical mass spectrometry (DEMS and fuel cell tests were conducted. It was found that fusel oil is not suitable as denaturing agent for DEFC. However, tert-butyl ethyl ether does not seem to hinder the ethanol conversion as much. Finally, a mixture of tert-butyl ethyl ether and Bitrex can be proposed as promising candidate as denaturing agent for use in acidic and alkaline DEFC.

Substituted N-Benzylpyrazine-2-carboxamides: Synthesis and Biological Evaluation

Directory of Open Access Journals (Sweden)

Katarína Kráľová

2012-11-01

Full Text Available A series of twelve amides was synthesized via aminolysis of substituted pyrazinecarboxylic acid chlorides with substituted benzylamines. Compounds were characterized with analytical data and assayed in vitro for their antimycobacterial, antifungal, antibacterial and photosynthesis-inhibiting activity. 5-tert-Butyl-6-chloro-N-(4-methoxybenzylpyrazine-2-carboxamide (12 has shown the highest antimycobacterial activity against Mycobacterium tuberculosis (MIC = 6.25 µg/mL, as well as against other mycobacterial strains. The highest antifungal activity against Trichophyton mentagrophytes, the most susceptible fungal strain tested, was found for 5-chloro-N-(3-trifluoromethylbenzyl-pyrazine-2-carboxamide (2, MIC = 15.62 µmol/L. None of the studied compounds exhibited any activity against the tested bacterial strains. Except for 5-tert-butyl-6-chloro-N-benzylpyrazine-2-carboxamide (9, IC50 = 7.4 µmol/L and 5-tert-butyl-6-chloro-N-(4-chlorobenzylpyrazine-2-carboxamide (11, IC50 = 13.4 µmol/L, only moderate or weak photosynthesis-inhibiting activity in spinach chloroplasts (Spinacia oleracea L. was detected.

Catalytic activity of metal borides in the reaction of decomposition

International Nuclear Information System (INIS)

Labodi, I.; Korablev, L.I.; Tavadyan, L.A.; Blyumberg, Eh.A.

1982-01-01

Catalytic effect of CoB, MoB 2 , ZrB 2 and NbB 2 , prepared by the method of self-propagating high-temperature synthesis, on decomposition of tertiary butyl hydroperoxide has been studied. A technigue of determination of action mechanism of heterogeneous catalysts in liquid-phase process is suggested. It is established that CoB in contrast to other metal borides catalyzes only hydroperoxide decomposition into radicals

The rapid detection of methyl tert-butyl ether (MtBE) in water using a prototype gas sensor system.

Science.gov (United States)

de Lacy Costello, B P J; Sivanand, P S; Ratcliffe, N M; Reynolds, D M

2005-01-01

The gasoline additive Methyl-tertiary-Butyl Ether (MtBE) is the second most common contaminant of groundwater in the USA and represents an important soil contaminant. This compound has been detected in the groundwater in at least 27 states as a result of leaking underground storage facilities (gasoline storage tanks and pipelines). Since the health effects of MtBE are unclear the potential threat to drinking water supplies is serious. Therefore, the ability to detect MtBE at low levels (ppb) and on-line at high-risk groundwater sites would be highly desirable. This paper reports the use of 'commercial' and metal oxide sensor arrays for the detection of MtBE in drinking and surface waters at low ppb level (microg.L(-1) range). The output responses from some of the sensors were found to correlate well with MtBE concentrations under laboratory conditions.

40 CFR 302.4 - Designation of hazardous substances.

Science.gov (United States)

2010-07-01

... 7803-55-6 4 P119 1000 (454) Amyl acetate 628-63-7 1 5000 (2270) iso-Amyl acetate 123-92-2 sec-Amyl... N.A. 2,3 ** Antimony Compounds N.A. 2,3 ** Antimony pentachloride 7647-18-9 1 1000 (454) Antimony... 5000 (2270) iso-Butyl acetate 110-19-0 sec-Butyl acetate 105-46-4 tert-Butyl acetate 540-88-5 n-Butyl...

Hydroperoxide Traces in Common Cyclic Ethers as Initiators for Controlled RAFT Polymerizations.

Science.gov (United States)

Eggers, Steffen; Abetz, Volker

2018-04-01

Herein, a reversible addition-fragmentation chain transfer (RAFT) polymerization is introduced for reactive monomers like N-acryloylpyrrolidine or N,N-dimethylacrylamide working without a conventional radical initiator. As a very straightforward proof of principle, the method takes advantage of the usually inconvenient radical-generating hydroperoxide contaminations in cyclic ethers like tetrahydrofuran or 1,4-dioxane, which are very common solvents in polymer sciences. The polymerizations are surprisingly well controlled and the polymers can be extended with a second block, indicating their high livingness. "Solvent-initiated" RAFT polymerizations hence prove to be a feasible access to tailored materials with minimal experimental effort and standard laboratory equipment, only requiring the following ingredients: hydroperoxide-contaminated solvent, monomer, and RAFT agent. In other respects, however, the potential coinitiating ability of the used solvent is to be considered when investigating the kinetics of RAFT polymerizations or aiming for the synthesis of high-livingness polymers, e.g., multiblock copolymers. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Role of hTERT in apoptosis of cervical cancer induced by histone deacetylase inhibitor

International Nuclear Information System (INIS)

Wu, Peng; Meng, Li; Wang, Hui; Zhou, Jianfeng; Xu, Gang; Wang, Shixuan; Xi, Ling; Chen, Gang; Wang, Beibei; Zhu, Tao; Lu, Yunping; Ma, Ding

2005-01-01

Human telomerase reverse transcriptase (hTERT) is the catalytic subunit of telomerase holoenzyme as well as the rate-limiting component of the telomerase enzyme complex. However, the role of the hTERT in apoptosis induced by histone deacetylase inhibitor has only been marginally addressed. For the first time, our study demonstrated that trichostatin A (TSA) briefly activated the proliferation of cervical cancer cell lines, HeLa and SiHa, within 12 h, but then inhibited cell growth after that time point. In response to TSA, hTERT expression, telomerase activity, and telomere length also underwent similar changes during the same time frame. Furthermore, the data in our study showed that cells transfected with dominant negative hTERT were more likely to undergo apoptosis induced by TSA than cells transfected with wild-type hTERT. The cyclin/cdk inhibitor p21 waf1 was down-regulated by hTERT without changing the expression of p53. Results from this study suggest that the hTERT might be a primary target of TSA and the anti-apoptosis effect of hTERT might be carried out through a p21 waf1 -dependent and p53-independent pathway

Functional and gene expression analysis of hTERT overexpressed endothelial cells

Directory of Open Access Journals (Sweden)

Haruna Takano

2008-09-01

Full Text Available Haruna Takano1, Satoshi Murasawa1,2, Takayuki Asahara1,2,31Institute of Biomedical Research and Innovation, Kobe, Japan; 2RIKEN Center for Developmental Biology, Kobe 650-0047, Japan; 3Tokai University of School of Medicine, Tokai, JapanAbstract: Telomerase dysfunction contributes to cellular senescence. Recent advances indicate the importance of senescence in maintaining vascular cell function in vitro. Human telomerase reverse transcriptase (hTERT overexpression is thought to lead to resistance to apoptosis and oxidative stress. However, the mechanism in endothelial lineage cells is unclear. We tried to generate an immortal endothelial cell line from human umbilical vein endothelial cells using a no-virus system and examine the functional mechanisms of hTERT overexpressed endothelial cell senescence in vitro. High levels of hTERT genes and endothelial cell-specific markers were expressed during long-term culture. Also, angiogenic responses were observed in hTERT overexpressed endothelial cell. These cells showed a delay in senescence and appeared more resistant to stressed conditions. PI3K/Akt-related gene levels were enhanced in hTERT overexpressed endothelial cells. An up-regulated PI3K/Akt pathway caused by hTERT overexpression might contribute to anti-apoptosis and survival effects in endothelial lineage cells.Keywords: endothelial, telomerase, senescence, oxidative stress, anti-apoptosis, PI3K/Akt pathway

Group 11 Metal Compounds with Tripodal Bis(imidazole Thioether Ligands. Applications as Catalysts in the Oxidation of Alkenes and as Antimicrobial Agents

Directory of Open Access Journals (Sweden)

Armando Varela-Ramírez

2011-08-01

Full Text Available New group 11 metal complexes have been prepared using the previously described tripodal bis(imidazole thioether ligand (N-methyl-4,5-diphenyl-2-imidazolyl2C(OMeC(CH32S(tert-Bu ({BITOMe,StBu}, 2. The pincer ligand offers a N2S donor atom set that can be used to coordinate the group 11 metals in different oxidation states [AuI, AuIII, AgI, CuI and CuII]. Thus the new compounds [Au{BITOMe,StBu}Cl][AuCl4]2 (3, [Au{BITOMe,StBu}Cl] (4, [Ag{BITOMe,StBu}X] (X = OSO2CF3- 5, PF6- 6 and [Cu{BITOMe,StBu}Cl2] (7 have been synthesized from reaction of 2 with the appropriate metal precursors, and characterized in solution. While attempting characterization in the solid state of 3, single crystals of the neutral dinuclear mixed AuIII-AuI species [Au2{BITOMe,S}Cl3] (8 were obtained and its crystal structure was determined by X-ray diffraction studies. The structure shows a AuIII center coordinated to the pincer ligand through one N and the S atom. The soft AuI center coordinates to the ligand through the same S atom that has lost the tert-butyl group, thus becoming a thiolate ligand. The short distance between the AuI-AuIII atoms (3.383 Å may indicate a weak metal-metal interaction. Complexes 2-7 and the previously described CuI compound [Cu{BITOMe,StBu}]PF6 (9 have been evaluated in the oxidation of biphenyl ethylene with tert-butyl hydrogen peroxide (TBHP as the oxidant. Results have shown that the AuI and AgI complexes 4 and 6 (at 10 mol % loading are the more active catalysts in this oxidative cleavage. The antimicrobial activity of compounds 2-5, 7 and 9 against Gram-positive and Gram-negative bacteria and yeast has also been evaluated. The new gold and silver compounds display moderate to high antibacterial activity, while the copper derivatives are mostly inactive. The gold and silver complexes were also potent against fungi. Their cytotoxic properties have been analyzed in vitro utilizing HeLa human cervical carcinoma cells. The compounds displayed a

Chemical kinetic study of a novel lignocellulosic biofuel: Di-n-butyl ether oxidation in a laminar flow reactor and flames

KAUST Repository

Cai, Liming; Sudholt, Alena; Lee, Dongjoon; Egolfopoulos, Fokion N.; Pitsch, Heinz G.; Westbrook, Charles K.; Sarathy, Mani

2014-01-01

The combustion characteristics of promising alternative fuels have been studied extensively in the recent years. Nevertheless, the pyrolysis and oxidation kinetics for many oxygenated fuels are not well characterized compared to those of hydrocarbons. In the present investigation, the first chemical kinetic study of a long-chain linear symmetric ether, di-n-butyl ether (DBE), is presented and a detailed reaction model is developed. DBE has been identified recently as a candidate biofuel produced from lignocellulosic biomass. The model includes both high temperature and low temperature reaction pathways with reaction rates generated using appropriate rate rules. In addition, experimental studies on fundamental combustion characteristics, such as ignition delay times and laminar flame speeds have been performed. A laminar flow reactor was used to determine the ignition delay times of lean and stoichiometric DBE/air mixtures. The laminar flame speeds of DBE/air mixtures were measured in the stagnation flame configuration for a wide rage of equivalence ratios at atmospheric pressure and an unburned reactant temperature of 373. K. All experimental data were modeled using the present kinetic model. The agreement between measured and computed results is satisfactory, and the model was used to elucidate the oxidation pathways of DBE. The dissociation of keto-hydroperoxides, leading to radical chain branching was found to dominate the ignition of DBE in the low temperature regime. The results of the present numerical and experimental study of the oxidation of di-n-butyl ether provide a good basis for further investigation of long chain linear and branched ethers. © 2013 The Combustion Institute.

Chemical kinetic study of a novel lignocellulosic biofuel: Di-n-butyl ether oxidation in a laminar flow reactor and flames

KAUST Repository

Cai, Liming

2014-03-01

The combustion characteristics of promising alternative fuels have been studied extensively in the recent years. Nevertheless, the pyrolysis and oxidation kinetics for many oxygenated fuels are not well characterized compared to those of hydrocarbons. In the present investigation, the first chemical kinetic study of a long-chain linear symmetric ether, di-n-butyl ether (DBE), is presented and a detailed reaction model is developed. DBE has been identified recently as a candidate biofuel produced from lignocellulosic biomass. The model includes both high temperature and low temperature reaction pathways with reaction rates generated using appropriate rate rules. In addition, experimental studies on fundamental combustion characteristics, such as ignition delay times and laminar flame speeds have been performed. A laminar flow reactor was used to determine the ignition delay times of lean and stoichiometric DBE/air mixtures. The laminar flame speeds of DBE/air mixtures were measured in the stagnation flame configuration for a wide rage of equivalence ratios at atmospheric pressure and an unburned reactant temperature of 373. K. All experimental data were modeled using the present kinetic model. The agreement between measured and computed results is satisfactory, and the model was used to elucidate the oxidation pathways of DBE. The dissociation of keto-hydroperoxides, leading to radical chain branching was found to dominate the ignition of DBE in the low temperature regime. The results of the present numerical and experimental study of the oxidation of di-n-butyl ether provide a good basis for further investigation of long chain linear and branched ethers. © 2013 The Combustion Institute.

The retro Grignard addition reaction revisited: the reversible addition of benzyl reagents to ketones

DEFF Research Database (Denmark)

Christensen, Stig Holden; Holm, Torkil; Madsen, Robert

2014-01-01

transformation. The retro benzyl reaction was shown by the addition of benzylmagnesium chloride to di-tert-butyl ketone followed by exchange of both the benzyl and the ketone moiety with another substrate. Similar experiments were performed with phenylmagnesium bromide and tert-butylmagnesium chloride...

[Effects of Astragali Radix combined with Angelicae Sinensis Radix on the proliferation of hematopoietic stem cells senescence model in mice].

Science.gov (United States)

Zhang, Ke-Sheng; Chen, Ling-Bo; Huang, Xiao-Ping; Deng, Chang-Qing

2017-11-01

The aim is to study the effect and its mechanism of Astragalus Radix combined with Angelicae Sinensis Radix on the proliferation of hematopoietic stem cells(HSCs) in senescence model. After drug-containing plasma of rats was prepared via intragastric administration, HSCs of mice were cultured in vitro, and then they were divided into blank control group, model group, blank plasma group, Astragalus Radix + Angelicae Sinensis Radix 1∶1 group and 10∶1 group, Angelicae Sinensis Radix plasma group, and Astragalus Radix plasma group. HSCs senescence model was induced by using tert-butyl hydrogen peroxide(t-BHP), and intervened by drug-containing plasma. Cells senescence rate was tested by SA-β-galactosidase staining method; cell cycle distribution was determined by flow cytometry; Cyclin D1, P21, and P53 mRNA were measured with RT-PCR, and Cyclin D1 protein expression was measured by Western blot. Results showed that after being induced by t-BHP, senescence rate of HSCs was increased; cell proliferation ability was decreased; count of G₀/G₁ phase cells was increased; count of G₂/M+S phase cells was reduced; Cyclin D1 expression was down-regulated while P53, P21 expression was up-regulated, which were reversed by Astragalus Radix + Angelicae Sinensis Radix 1∶1 and 10∶1, single Angelicae Sinensis Radix, and single Astragalus Radix plasma. Furthermore, the above effects were most obvious in Astragalus Radix+Angelicae Sinensis Radix 1∶1 group. These results suggested that t-BHP can promote HSCs senescence and reduce cell proliferation ability. Angelicae Sinensis Radix, Astragalus Radix and their combinations can inhibit HSCs senescence, promote HSCs proliferation as well as cell cycle conversion; moreover, the effects of 1∶1 Astragalus Radix+Angelicae Sinensis Radix were strongest. The mechanisms may be related to up-regulating the expression of cell cycle positive regulator, down-regulating the expression of cell cycle negative regulator, thus promoting

EFFECT OF BTEX ON THE DEGRADATION OF MTBE AND TBA BY MIXED BACTERIAL CONSORTIUM

Science.gov (United States)

Methyl tert-butyl ether (MTBE) contamination in groundwater often coexists with benzene, toluene, ethylbenzene, and xylene (BTEX) near the source of the plume. Tertiary butyl alcohol (TBA) is a prevalent intermediate of MTBE degradation. Therefore, there is a significant p...

The neuroprotective role and mechanisms of TERT in neurons with oxygen-glucose deprivation.

Science.gov (United States)

Li, J; Qu, Y; Chen, D; Zhang, L; Zhao, F; Luo, L; Pan, L; Hua, J; Mu, D

2013-11-12

Telomerase reverse transcriptase (TERT) is reported to protect neurons from apoptosis induced by various stresses including hypoxia-ischemia (HI). However, the mechanisms by which TERT exerts its anti-apoptotic role in neurons with HI injury remain unclear. In this study, we examined the protective role and explored the possible mechanisms of TERT in neurons with HI injury in vitro. Primary cultured neurons were exposed to oxygen and glucose deprivation (OGD) for 3h followed by reperfusion to mimic HI injury in vivo. Plasmids containing TERT antisense, sense nucleotides, or mock were transduced into neurons at 48h before OGD. Expression and distribution of TERT were measured by immunofluorescence labeling and western blot. The expression of cleaved caspase 3 (CC3), Bcl-2 and Bax were detected by western blot. Neuronal apoptosis was measured with terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL). The mitochondrial reactive oxygen species (ROS) were measured by MitoSOX Red staining. Fluorescent probe JC-1 was used to measure the mitochondrial membrane potential (ΔΨm). We found that TERT expression increased at 8h and peaked at 24h in neurons after OGD. CC3 expression and neuronal apoptosis were induced and peaked at 24h after OGD. TERT inhibition significantly increased CC3 expression and neuronal apoptosis after OGD treatment. Additionally, TERT inhibition decreased the expression ratio of Bcl-2/Bax, and enhanced ROS production and ΔΨm dissipation after OGD. These data suggest that TERT plays a neuroprotective role via anti-apoptosis in neurons after OGD. The underlying mechanisms may be associated with regulating Bcl-2/Bax expression ratio, attenuating ROS generation, and increasing mitochondrial membrane potential. Copyright © 2013 IBRO. Published by Elsevier Ltd. All rights reserved.

Regulation of hTERT by BCR-ABL at multiple levels in K562 cells

International Nuclear Information System (INIS)

Chai, Juin Hsien; Zhang, Yong; Tan, Wei Han; Chng, Wee Joo; Li, Baojie; Wang, Xueying

2011-01-01

The cytogenetic characteristic of Chronic Myeloid Leukemia (CML) is the formation of the Philadelphia chromosome gene product, BCR-ABL. Given that BCR-ABL is the specific target of Gleevec in CML treatment, we investigated the regulation of the catalytic component of telomerase, hTERT, by BCR-ABL at multiple levels in K562 cells. Molecular techniques such as over expression, knockdown, real-time PCR, immunoprecipitation, western blotting, reporter assay, confocal microscopy, telomerase assays and microarray were used to suggest that hTERT expression and activity is modulated by BCR-ABL at multiple levels. Our results suggest that BCR-ABL plays an important role in regulating hTERT in K562 (BCR-ABL positive human leukemia) cells. When Gleevec inhibited the tyrosine kinase activity of BCR-ABL, phosphorylation of hTERT was downregulated, therefore suggesting a positive correlation between BCR-ABL and hTERT. Gleevec treatment inhibited hTERT at mRNA level and significantly reduced telomerase activity (TA) in K562 cells, but not in HL60 or Jurkat cells (BCR-ABL negative cells). We also demonstrated that the transcription factor STAT5a plays a critical role in hTERT gene regulation in K562 cells. Knockdown of STAT5a, but not STAT5b, resulted in a marked downregulation of hTERT mRNA level, TA and hTERT protein level in K562 cells. Furthermore, translocation of hTERT from nucleoli to nucleoplasm was observed in K562 cells induced by Gleevec. Our data reveal that BCR-ABL can regulate TA at multiple levels, including transcription, post-translational level, and proper localization. Thus, suppression of cell growth and induction of apoptosis by Gleevec treatment may be partially due to TA inhibition. Additionally, we have identified STAT5a as critical mediator of the hTERT gene expression in BCR-ABL positive CML cells, suggesting that targeting STAT5a may be a promising therapeutic strategy for BCR-ABL positive CML patients

A Novel Strategy Towards the Asymmetric Synthesis of Orthogonally Funtionalised 2-N-Benzyl-N-α-methylbenzylamino- 5-carboxymethyl-cyclopentane-1-carboxylic acid.

Directory of Open Access Journals (Sweden)

Julio G. Urones

2004-04-01

Full Text Available The asymmetric synthesis of the orthogonally funtionalised compounds tert-butyl 2-N-benzyl-N-α-methylbenzylamino-5-methoxycarbonylmethylcyclopentane- 1-carboxylate and methyl 2-N-benzyl-N-α-methylbenzylamino-5–carboxymethylcyclo- pentane-1-carboxylate by a domino reaction of tert-butyl methyl (E,E-octa-2,6- diendioate with lithium N-α-methylbenzyl-N-benzylamide initiated by a Michael addition, subsequent 5-exo-trig intramolecular cyclisation and posterior selective hydrolysis with trifluoroacetic acid is reported.

Palladium-catalysed arylation of acetoacetate esters to yield 2-arylacetic acid esters

CSIR Research Space (South Africa)

Zeevaart, JG

2004-05-24

Full Text Available , was developed simultaneously by Hart- wig and Buchwald.5 Typically the tert-butyl ester of propionic acid is treated with an aryl halide (bromide or chloride) in the presence of a strong base, palladium and a bulky phosphine ligand or a bulky imidazolinium CO2t... novel palladium- catalysed conditions for the arylation of acetoacetate esters resulting in the formation of 2-arylacetic acid esters. When we attempted the arylation of tert-butyl aceto- acetate 1a with bromobenzene 2a using mild reaction conditions (K3...

The synthesis and spectroscopic study of stable free radicals related to piperidine-n-oxyl, including a stable bi-radical; Syntheses et etudes spectroscopiques de radicaux libres piperidiniques et d'un biradical stable, du type nitroxyde

Energy Technology Data Exchange (ETDEWEB)

Briere, R [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires, Laboratoire de chimie organique physique

1967-06-01

A new synthesis of di-tert-butyl nitroxide using the reaction between tert-butyl magnesium chloride and nitro-tert-butane is presented in the first section. Synthesis and investigation of stable free piperidine-N-oxyl radicals are described in the second section. All these nitroxides have been characterised by their I. R., U. V. and E. P. R. absorption spectra. The final section contains a description of the synthesis of a stable bi-radical of the nitroxide type by condensation of 2,2, 6, 6-tetramethyl-piperid-4-one-l-oxyl with hydrazine. (author) [French] La premiere partie expose une nouvelle methode de synthase du di-t-butyl nitroxyde, par action d'halogenures de t-butyl magnesium sur le nitro-t-butane (Rdt maximum 45 pour cert, purete 86 pour cent). Une etude de radicaux. libres stables pipericliniques est faite dans une seconde partie. Ces composes sont obtenus par oxydation de derives de la triacetonamine. Les caracteristiques spectroscopiques ultra-violette, infra-rouge, et paramagnetique electronique de ces radicaux sont donnees. La grande inertie chimique du groupement nitroxyde a permis la syn-these d'un biradical stable par formation d'azine d'une cetone radicalaire, ce qui fait 1'objet de la troisieme partie. (auteur)

Intake of butylated hydroxyanisole and butylated hydroxytoluene and stomach cancer risk : results from analyses in the Netherlands : cohort study

NARCIS (Netherlands)

Botterweck, A.A.M.; Verhagen, H.; Goldbohm, R.A.; Kleinjans, J.; Brandt, P.A. van den

2000-01-01

Both carcinogenic and anticarcinogenic properties have been reported for the synthetic antioxidants butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). The association between dietary intake of BHA and BHT and stomach cancer risk was investigated in the Netherlands Cohort Study (NLCS)

Deaminated zeolite, ITQ-6 as heterogeneous catalyst for Friedel crafts alkylation

International Nuclear Information System (INIS)

Zainab Ramli; Noor Ashikin Mohd Yusoff; Halimaton Hamdan

2007-01-01

The ability of ITQ-6, a kind of meso porous zeolitic material to replace microporous zeolite as catalyst has attracted particular attention. In this study, modification of a precursor of microporous ferrierite, PREFER to meso porous material, ITQ-6 was carried out by delamination technique. The XRD results show that the crystalline phase of PREFER diminished for the sample after delamination. Porosity study of the ITQ-6 sample shows formation of homogeneous meso pores in the size between 3.5-4.0 nm. The acidity study indicates that ITQ-6 still contains appreciable amounts of Bronsted and Lewis acidities. Catalytic evaluation of the resulting material, ITQ-6 was carried out in the alkylation of resorcinol with methyl tert-butyl ether which gave 4-tert-butyl resorcinol and 4, 6-di-tert-butyl resorcinol as main products. The conversion of resorcinol when using ITQ-6 was ten times higher than ferrierite, FER with similar selectivity of disubstituted product. It shows that the meso porosity of ITQ-6 was responsible for the higher activity of the catalyst in the reaction. (author)

Limitations in MTBE biodegradation; Etapes limitantes dans la biodegradation du MTBE

Energy Technology Data Exchange (ETDEWEB)

Fayolle, F.; Francois, A.; Garnier, L.; Godefroy, D.; Mathis, H.; Piveteau, P.; Monot, F. [Institut Francais du Petrole (IFP), Dept. Biotechnologie et Chimie de la Biomasse, 92 - Rueil-Malmaison (France)

2003-08-01

The methyl tert-butyl ether (MTBE) metabolic pathway was partially elucidated in Mycobacterium austroafricanum IFP 2012 by identifying the degradation intermediates. Several enzymatic activities were specifically induced during growth on MTBE. Among those required for the first steps of MTBE degradation to tert-butyl alcohol (TBA), the same monooxygenase was responsible for the oxidation of both MTBE and TBA, with a low affinity for TBA (Km = 1.1 mM). An esterase was involved in the hydrolysis of tert-butyl formate (TBF). The slowness of the degradation of MTBE by M. austroafricanum IFP 2012 was the result of complex interactions, especially the negative effect of TBF formed during MTBE oxidation on the MTBE/TBA mono-oxygenase and the absence of TBA oxidation in the presence of residual MTBE. Moreover, concerning the downstream steps of MTBE metabolism, Co{sup ++} ions were required for the degradation of 2-hydroxy-isobutyric acid (HIBA) formed by oxidation of TBA as shown by the low growth yield on HIBA in the absence of cobalt. (authors)

Novel non-symmetrical bifunctionally-substituted phthalonitriles and corresponding d-metal phthalocyaninates

Science.gov (United States)

Vashurin, Artur; Maizlish, Vladimir; Tikhomirova, Tatiyana; Nemtseva, Marina; Znoyko, Serafima; Aleksandriiskii, Viktor

2018-05-01

The work reports synthesis of 4-(2-tert-butyl-4,5-dicyanophenylsulfonyl)benzene and its analogue containing carboxyl group in phenyl fragment by nucleophilic substitution of nitro-group of 4-tert-butyl-5-nitrophthalonitrile. Unique structure of the obtained compounds is explained by presence of bulky tert-butyl substituent in combination with carboxyl group, which being part of phthalocyanine molecule impart it higher solubility within different solvents (organic and water mediums) and act as anchoring groups. Based on obtained nitriles phthalocyanine complexes of copper, nickel, cobalt and magnesium are synthesized with good yields. Demetallization of initial magnesium phthalocyanine by hydrochloric acid was performed in order to obtain ligand of phthalocyanine. Synthetic and purification techniques are described in detail. Obtained substances are of specific structure making them to be applied in sensorics for smart materials production, as sensitizers or part of molecular magnets. The structure, NMR and IR spectra are modeled using special software. Resulting experimental and theoretical data are compared. The results show sufficient correlation that confirms correctness of chosen methods and its applicability for theoretical studying compounds related to investigated ones.

Tailoring the Structure of Two-Dimensional Self-Assembled Nanoarchitectures Based on Ni^II–Salen Building Blocks

DEFF Research Database (Denmark)

Viciano-Chumillas, Marta; Li, Dongzhe; Smogunov, Alexander

2014-01-01

-butyl) is presented. Their electronic structure and self-assembly was studied. The organic ligands of the salen complexes are functionalized with peripheral carboxylic groups for driving molecular self-assembly through hydrogen bonding. In addition, other substituents, that is, tert-butyl and diamine bridges (2...

Germline TERT promoter mutations are rare in familial melanoma

DEFF Research Database (Denmark)

Harland, Mark; Petljak, Mia; Robles-Espinoza, Carla Daniela

2016-01-01

Germline CDKN2A mutations occur in 40 % of 3-or-more case melanoma families while mutations of CDK4, BAP1, and genes involved in telomere function (ACD, TERF2IP, POT1), have also been implicated in melanomagenesis. Mutation of the promoter of the telomerase reverse transcriptase (TERT) gene (c.-57...... T>G variant) has been reported in one family. We tested for the TERT promoter variant in 675 multicase families wild-type for the known high penetrance familial melanoma genes, 1863 UK population-based melanoma cases and 529 controls. Germline lymphocyte telomere length was estimated in carriers....... The c.-57 T>G TERT promoter variant was identified in one 7-case family with multiple primaries and early age of onset (earliest, 15 years) but not among population cases or controls. One family member had multiple primary melanomas, basal cell carcinomas and a bladder tumour. The blood leukocyte...

Allele-Specific DNA Methylation and Its Interplay with Repressive Histone Marks at Promoter-Mutant TERT Genes

Directory of Open Access Journals (Sweden)

Josh Lewis Stern

2017-12-01

Full Text Available A mutation in the promoter of the Telomerase Reverse Transcriptase (TERT gene is the most frequent noncoding mutation in cancer. The mutation drives unusual monoallelic expression of TERT, allowing immortalization. Here, we find that DNA methylation of the TERT CpG island (CGI is also allele-specific in multiple cancers. The expressed allele is hypomethylated, which is opposite to cancers without TERT promoter mutations. The continued presence of Polycomb repressive complex 2 (PRC2 on the inactive allele suggests that histone marks of repressed chromatin may be causally linked to high DNA methylation. Consistent with this hypothesis, TERT promoter DNA containing 5-methyl-CpG has much increased affinity for PRC2 in vitro. Thus, CpG methylation and histone marks appear to collaborate to maintain the two TERT alleles in different epigenetic states in TERT promoter mutant cancers. Finally, in several cancers, DNA methylation levels at the TERT CGI correlate with altered patient survival.

Studies on the separation of {sup 89}Sr(II) from irradiated yttria target using 4, 4{sup '}(5{sup '}) di-tert-butyl-cyclohexano-18-crown-6 (DtBuCH18C6) by solvent extraction technique

Energy Technology Data Exchange (ETDEWEB)

Saha, Debasish; Vithya, Jayagopal; Kumar, Ramalingam; Venkata Subramani, Canchipuram Ramamoorthy; Vasudeva Rao, Polur Ranga [Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam (India). Chemistry Group

2016-07-01

The radioisotope {sup 89}Sr as {sup 89}SrCl{sub 2} is medically useful for bone pain palliation and is produced in fast reactors using the {sup 89}Y(n, p){sup 89}Sr reaction. A procedure for isolation of the radionuclide {sup 89}Sr by chemical processing of the irradiated Y{sub 2}O{sub 3} target has been standardised and trial runs have been carried out at the Fast Breeder Test Reactor (FBTR), Kalpakkam. The chemical processing of the irradiated Y{sub 2}O{sub 3} target involves (i) the removal of target Y(III) by TBP extraction and (ii) further purification of the separated {sup 89}Sr fraction by cationic exchange chromatography. However a selective isolation of {sup 89}Sr by the Sr-specific crown ether makes the above chemical processing faster and relatively simple. This work presents a study on the selective removal of Sr from the irradiated target dissolver solution using the Sr-specific crown ether 4,4{sup '}(5{sup '}) di-tert-butyl-cyclohexano-18-crown-6 (DtBuCH18C6) in octanol medium. The separation behaviour of the other impurities such as Ce(IV), Y(III), Tb(III), Eu(III), Zn(II), Mn(II) and Rb(I) present along with Sr(II) in the irradiated sample was also investigated. The method of separation by using the crown ether DtBuCH18C6 is proved to be a potential tool for the purification of {sup 89}Sr(II) source produced from yttria target in fast reactors.

In vitro growth inhibition of mastitis causing bacteria by phenolics and metal chelators

Energy Technology Data Exchange (ETDEWEB)

Chew, B.P.; Tjoelker, L.W.; Tanaka, T.S.

1985-11-01

Antimicrobial activities of three phenolic compounds and four metal chelators were tested at 0, 250, 500, and 1000 ppm in vitro against four major mastitis-causing bacteria, Streptococcus agalactiae, Staphylococcus aureus, Klebsiella pnuemoniae, and Escherichia coli. Overall, butylated hydroxyanisole and tert-butylhydroquinone showed the greatest antimicrobial activity. These phenolics were bactericidal at 250 to 500 ppm against all four bacteria tested. The butylated hydroxytoluene was bactericidal against the gram-positive bacteria but was ineffective against the coliforms. At 250 ppm, disodium ethylenediaminetetraacetic acid was bactericidal against the gram-positive bacteria but much less effective against the gram-negatives. However, diethylene-triaminepentaacetic acid was more growth inhibitory than ethylenediaminetetraacetic acid against the gram-negative bacteria and especially against Escherichia coli. All other compounds were generally much less effective or ineffective against all four microorganisms. Therefore, butylated hydroxyanisole, butylated hydroxytoluene, tert-butylhydroquinone, ethylenediaminetetraacetic acid, and diethylenetriaminepentaacetic acid may have practical implications in the prevention or treatment of bovine mastitis.

The Thr-His Connection on the Distal Heme of Catalase-Related Hemoproteins: A Hallmark of Reaction with Fatty Acid Hydroperoxides.

Science.gov (United States)

Mashhadi, Zahra; Newcomer, Marcia E; Brash, Alan R

2016-11-03

This review focuses on a group of heme peroxidases that retain the catalase fold in structure, yet show little or no reaction with hydrogen peroxide. Instead of having a role in oxidative defense, these enzymes are involved in secondary metabolite biosynthesis. The prototypical enzyme is catalase-related allene oxide synthase, an enzyme that converts a specific fatty acid hydroperoxide to the corresponding allene oxide (epoxide). Other catalase-related enzymes form allylic epoxides, aldehydes, or a bicyclobutane fatty acid. In all catalases (including these relatives), a His residue on the distal face of the heme is absolutely required for activity. Its immediate neighbor in sequence as well as in 3 D space is conserved as Val in true catalases and Thr in the fatty acid hydroperoxide-metabolizing enzymes. Thr-His on the distal face of the heme is critical in switching the substrate specificity from H 2 O 2 to fatty acid hydroperoxide. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Macrophage replication screen identifies a novel Francisella hydroperoxide resistance protein involved in virulence.

Directory of Open Access Journals (Sweden)

Anna C Llewellyn

Full Text Available Francisella tularensis is a gram-negative facultative intracellular pathogen and the causative agent of tularemia. Recently, genome-wide screens have identified Francisella genes required for virulence in mice. However, the mechanisms by which most of the corresponding proteins contribute to pathogenesis are still largely unknown. To further elucidate the roles of these virulence determinants in Francisella pathogenesis, we tested whether each gene was required for replication of the model pathogen F. novicida within macrophages, an important virulence trait. Fifty-three of the 224 genes tested were involved in intracellular replication, including many of those within the Francisella pathogenicity island (FPI, validating our results. Interestingly, over one third of the genes identified are annotated as hypothetical, indicating that F. novicida likely utilizes novel virulence factors for intracellular replication. To further characterize these virulence determinants, we selected two hypothetical genes to study in more detail. As predicted by our screen, deletion mutants of FTN_0096 and FTN_1133 were attenuated for replication in macrophages. The mutants displayed differing levels of attenuation in vivo, with the FTN_1133 mutant being the most attenuated. FTN_1133 has sequence similarity to the organic hydroperoxide resistance protein Ohr, an enzyme involved in the bacterial response to oxidative stress. We show that FTN_1133 is required for F. novicida resistance to, and degradation of, organic hydroperoxides as well as resistance to the action of the NADPH oxidase both in macrophages and mice. Furthermore, we demonstrate that F. holarctica LVS, a strain derived from a highly virulent human pathogenic species of Francisella, also requires this protein for organic hydroperoxide resistance as well as replication in macrophages and mice. This study expands our knowledge of Francisella's largely uncharacterized intracellular lifecycle and

Allele-Specific DNA Methylation and Its Interplay with Repressive Histone Marks at Promoter-Mutant TERT Genes.

Science.gov (United States)

Stern, Josh Lewis; Paucek, Richard D; Huang, Franklin W; Ghandi, Mahmoud; Nwumeh, Ronald; Costello, James C; Cech, Thomas R

2017-12-26

A mutation in the promoter of the Telomerase Reverse Transcriptase (TERT) gene is the most frequent noncoding mutation in cancer. The mutation drives unusual monoallelic expression of TERT, allowing immortalization. Here, we find that DNA methylation of the TERT CpG island (CGI) is also allele-specific in multiple cancers. The expressed allele is hypomethylated, which is opposite to cancers without TERT promoter mutations. The continued presence of Polycomb repressive complex 2 (PRC2) on the inactive allele suggests that histone marks of repressed chromatin may be causally linked to high DNA methylation. Consistent with this hypothesis, TERT promoter DNA containing 5-methyl-CpG has much increased affinity for PRC2 in vitro. Thus, CpG methylation and histone marks appear to collaborate to maintain the two TERT alleles in different epigenetic states in TERT promoter mutant cancers. Finally, in several cancers, DNA methylation levels at the TERT CGI correlate with altered patient survival. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

Aircraft and ground-based measurements of hydroperoxides during the 2006 MILAGRO field campaign

Directory of Open Access Journals (Sweden)

L. J. Nunnermacker

2008-12-01

Full Text Available Mixing ratios of hydrogen peroxide and hydroxymethyl hydroperoxide were determined aboard the US Department of Energy G-1 Research Aircraft during the March, 2006 MILAGRO field campaign in Mexico. Ground measurements of total hydroperoxide were made at Tecámac University, about 35 km NW of Mexico City. In the air and on the ground, peroxide mixing ratios near the source region were generally near 1 ppbv. Strong southerly flow resulted in transport of pollutants from Mexico City to two downwind surface sites on several flight days. On these days, it was observed that peroxide concentrations slightly decreased as the G-1 flew progressively downwind. This observation is consistent with low or negative net peroxide production rates calculated for the source region and is due to the very high NO_x concentrations in the Mexico City plateau. However, relatively high values of peroxide were observed at takeoff and landing near Veracruz, a site with much higher humidity and lower NO_x concentrations.

Photoelectrochemical determination of tert-butylhydroquinone in edible oil samples employing CdSe/ZnS quantum dots and LiTCNE.

Science.gov (United States)

Monteiro, Thatyara Oliveira; Tanaka, Auro Atsushi; Damos, Flávio Santos; Luz, Rita de Cássia Silva

2017-07-15

A novel photoelectrochemical sensor was developed for determination of tert-butyl-hydroquinone (TBHQ) in edible vegetable oils, based on CdSe/ZnS core-shell quantum dots sensitized with lithium tetracyanoethylenide (LiTCNE). The CdSe/ZnS/LiTCNE photoelectrochemical sensor presented a TBHQ photocurrent about 13-fold higher and a charge transfer resistance 62-fold lower than observed for a CdSe/ZnS sensor. The photoelectrochemical sensor showed selectivity to TBHQ, with a high photocurrent for this antioxidant compared to the photocurrent responses for other phenolic antioxidants. The CdSe/ZnS/LiTCNE photoelectrochemical sensor presented a linear range from 0.6 to 250μmolL -1 , sensitivity of 0.012μALμmol -1 , and a limit of detection of 0.21μmolL -1 for TBHQ, under optimized experimental conditions. The sensor was successfully employed in the analysis of edible oil samples, with recoveries of between 98.25% and 99.83% achieved. Copyright © 2017 Elsevier Ltd. All rights reserved.

Evidence of extra-telomeric effects of hTERT and its regulation involving a feedback loop

International Nuclear Information System (INIS)

Lai, Serene R.; Cunningham, Amanda P.; Huynh, Vu Q.; Andrews, Lucy G.; Tollefsbol, Trygve O.

2007-01-01

The human telomerase reverse transcriptase (hTERT) is the catalytic subunit of the enzyme telomerase which is responsible for telomeric maintenance and extension. Using RNA interference to knock down hTERT mRNA expression, we provide evidence that hTERT exerts extra-telomeric effects on the cell cycle and on its own regulatory proteins, specifically: p53 and p21. We tested our hypothesis that hTERT regulates its own expression through effects on upstream regulatory genes using transformed human embryonic kidney (HEK 293) cells, p53 and p16 INK4a null human ovarian cancer SKOV-3 cells, and p53-null MDA-MB-157 human mammary cancer cells. In HEK 293 cells, hTERT knockdown resulted in elevated p53 and p21 transcription and a decrease in cellular proliferation. Similar results were observed in the MDA-MB-157 cell line where p21 was upregulated, correlating with cell growth inhibition. In contrast, we observed a decrease in expression of p21 in SKOV-3 cells with hTERT knockdown and cell growth appeared to be unaffected. These findings suggest that hTERT may be involved in a feedback loop system, thereby playing a role in its own regulation

An oxidative cross-coupling reaction of 4-hydroxydithiocoumarin and amines/thiols using a combination of I2 and TBHP: access to lead molecules for biomedical applications.

Science.gov (United States)

Mahato, Karuna; Arora, Neha; Ray Bagdi, Prasanta; Gattu, Radhakrishna; Ghosh, Siddhartha Sankar; Khan, Abu T

2018-02-06

A metal-free I 2 /TBHP induced highly atom economic and operationally simple oxidative cross-coupling reaction has been developed for the direct synthesis of sulfenamides/sulfanes/disulfides from the reaction of 4-hydroxydithiocoumarin and amines/thiols. The novelties of the present protocol are unprecedented S-C bond formation in addition to S-N and S-S bonds, shorter reaction time, mild and environmentally benign reaction conditions, functional group tolerance and moderate to excellent yields. Moreover, the four newly synthesized compounds namely 4q, 6d, 6e and 7a exhibit anti-proliferative activity against the breast cancer cell line MCF7, and may be lead molecules for future drug development.

Gamma-radiation effect on thermal ageing of butyl rubber compounds

Energy Technology Data Exchange (ETDEWEB)

Scagliusi, Sandra R.; Cardoso, Elizabeth C.L.; Lugao, Ademar B., E-mail: srscagliusi@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2015-07-01

Butyl rubber has a comprehensive use in sealing systems, especially in tires inner tubes, due to their low permeability to gases. So, it is required that butyl rubber compounds show a better performance, more and more. Butyl rubber is provided with excellent mechanical properties and oxidation resistance. Besides showing these properties, radiation exposures impart modifications in physical-chemical and morphological properties on butyl rubber materials. When exposed to gamma-radiation, rubbers suffer changes in their mechanical and physical properties, caused by material degradation. The major radiation effect in butyl rubbers is chain scission; besides, ageing promotes too the same effect with further build-up of free radicals. This work aims to the study of gamma-radiation in physical-chemical properties of butyl rubber subjected to thermal ageing. Doses used herein were: 25 kGy, 50 kGy, 100 kGy, 150 kGy and 200 KGy. Samples were evaluated before and after ageing according to traditional essays, such as: hardness, tensile strength and elongation at break. From accomplished assessments it is possible to affirm that at doses higher than 50 kGy it was observed a sharp decreasing in butyl rubber physical-chemical properties, before and after exposure to ageing. (author)

Gamma-radiation effect on thermal ageing of butyl rubber compounds

International Nuclear Information System (INIS)

Scagliusi, Sandra R.; Cardoso, Elizabeth C.L.; Lugao, Ademar B.

2015-01-01

Butyl rubber has a comprehensive use in sealing systems, especially in tires inner tubes, due to their low permeability to gases. So, it is required that butyl rubber compounds show a better performance, more and more. Butyl rubber is provided with excellent mechanical properties and oxidation resistance. Besides showing these properties, radiation exposures impart modifications in physical-chemical and morphological properties on butyl rubber materials. When exposed to gamma-radiation, rubbers suffer changes in their mechanical and physical properties, caused by material degradation. The major radiation effect in butyl rubbers is chain scission; besides, ageing promotes too the same effect with further build-up of free radicals. This work aims to the study of gamma-radiation in physical-chemical properties of butyl rubber subjected to thermal ageing. Doses used herein were: 25 kGy, 50 kGy, 100 kGy, 150 kGy and 200 KGy. Samples were evaluated before and after ageing according to traditional essays, such as: hardness, tensile strength and elongation at break. From accomplished assessments it is possible to affirm that at doses higher than 50 kGy it was observed a sharp decreasing in butyl rubber physical-chemical properties, before and after exposure to ageing. (author)

Repression of hTERT transcription by the introduction of chromosome 3 into human oral squamous cell carcinoma

Energy Technology Data Exchange (ETDEWEB)

Nishio, Sachiyo [Division of Oral and Maxillofacial Biopathological Surgery, Faculty of Medicine, Tottori University, 86 Nishi-cho, Yonago, Tottori, 683-8503 (Japan); Department of Biomedical Science, Institute of Regenerative Medicine and Biofunction, Graduate School of Medical Science, Tottori University, Yonago, Tottori, 683-8503 (Japan); Ohira, Takahito; Sunamura, Naohiro [Department of Biomedical Science, Institute of Regenerative Medicine and Biofunction, Graduate School of Medical Science, Tottori University, Yonago, Tottori, 683-8503 (Japan); Oshimura, Mitsuo [Chromosome Engineering Research Center, Tottori University, Yonago, Tottori, 683-8503 (Japan); Ryoke, Kazuo [Division of Oral and Maxillofacial Biopathological Surgery, Faculty of Medicine, Tottori University, 86 Nishi-cho, Yonago, Tottori, 683-8503 (Japan); Kugoh, Hiroyuki, E-mail: kugoh@med.tottori-u.ac.jp [Department of Biomedical Science, Institute of Regenerative Medicine and Biofunction, Graduate School of Medical Science, Tottori University, Yonago, Tottori, 683-8503 (Japan); Chromosome Engineering Research Center, Tottori University, Yonago, Tottori, 683-8503 (Japan)

2015-10-30

Telomerase is a ribonucleoprotein enzyme that maintains telomere length. Telomerase activity is primarily attributed to the expression of telomerase reverse transcriptase (TERT). It has been reported that introduction of an intact human chromosome 3 into the human oral squamous cell carcinoma cell line HSC3 suppresses the tumorigenicity of these cells. However, the mechanisms that regulate tumorigenicity have not been elucidated. To determine whether this reduction in tumorigenicity was accompanied by a reduction in telomerase activity, we investigated the transcriptional activation of TERT in HSC3 microcell hybrid clones with an introduced human chromosome 3 (HSC3#3). HSC#3 cells showed inhibition of hTERT transcription compared to that of the parental HSC3 cells. Furthermore, cell fusion experiments showed that hybrids of HSC3 cells and cells of the RCC23 renal carcinoma cell line, which also exhibits suppression of TERT transcription by the introduction of human chromosome 3, also displayed suppressed TERT transcription. These results suggested that human chromosome 3 may carry functionally distinct, additional TERT repressor genes. - Highlights: • hTERT mRNA expression level decreased in the chromosome 3 introduced HSC3 clones. • hTERT mRNA expression level was tend to suppressed in HSC3 and RCC23 hybrid cells. • We provide evidence that human chromosome 3 carries at least two distinct hTERT regulatory factors.

Repression of hTERT transcription by the introduction of chromosome 3 into human oral squamous cell carcinoma

International Nuclear Information System (INIS)

Nishio, Sachiyo; Ohira, Takahito; Sunamura, Naohiro; Oshimura, Mitsuo; Ryoke, Kazuo; Kugoh, Hiroyuki

2015-01-01

Telomerase is a ribonucleoprotein enzyme that maintains telomere length. Telomerase activity is primarily attributed to the expression of telomerase reverse transcriptase (TERT). It has been reported that introduction of an intact human chromosome 3 into the human oral squamous cell carcinoma cell line HSC3 suppresses the tumorigenicity of these cells. However, the mechanisms that regulate tumorigenicity have not been elucidated. To determine whether this reduction in tumorigenicity was accompanied by a reduction in telomerase activity, we investigated the transcriptional activation of TERT in HSC3 microcell hybrid clones with an introduced human chromosome 3 (HSC3#3). HSC#3 cells showed inhibition of hTERT transcription compared to that of the parental HSC3 cells. Furthermore, cell fusion experiments showed that hybrids of HSC3 cells and cells of the RCC23 renal carcinoma cell line, which also exhibits suppression of TERT transcription by the introduction of human chromosome 3, also displayed suppressed TERT transcription. These results suggested that human chromosome 3 may carry functionally distinct, additional TERT repressor genes. - Highlights: • hTERT mRNA expression level decreased in the chromosome 3 introduced HSC3 clones. • hTERT mRNA expression level was tend to suppressed in HSC3 and RCC23 hybrid cells. • We provide evidence that human chromosome 3 carries at least two distinct hTERT regulatory factors.

Chemiluminescent Diagnostics of Free-Radical Processes in an Abiotic System and in Liver Cells in the Presence of Nanoparticles Based on Rare-Earth Elements nReVO4:Eu3+ (Re = Gd, Y, La) and CeO2

Science.gov (United States)

Averchenko, E. A.; Kavok, N. S.; Klochkov, V. K.; Malyukin, Yu. V.

2014-11-01

We have used luminol-dependent chemiluminescence with Fenton's reagent to study the effect of nanoparticles based on rare-earth elements of different sizes and shapes on free-radical processes in abiotic and biotic cell-free systems, and also in isolated cells in vitro. We have estimated the effects of rare-earth orthovanadate nanoparticles of spherical (GdYVO4:Eu3+, 1-2 nm), spindle-shaped (GdVO4:Eu3+, 25 ×8 nm), and rod-shaped (LaVO4:Eu3+, 57 × (6-8) nm) nanoparticles and spherical CeO2 nanoparticles (sizes 1-2 nm and 8-10 nm). We have shown that in contrast to the abiotic system, in which all types of nanoparticles exhibit antiradical activity, in the presence of biological material, extra-small spherical (1-2 nm) nanoparticles of both types exhibit pro-oxidant activity, and also enhance pro-oxidant induced oxidative stress (for the pro-oxidants hydrogen peroxide and tert-butyl hydroperoxide). The effect of rare-earth orthovanadate spindle and rod shaped nanoparticles in this system was neutral; a moderate antioxidant effect was exhibited by 8-10 nm CeO2 nanoparticles.

Antinociceptive effects of fisetin against diabetic neuropathic pain in mice: Engagement of antioxidant mechanisms and spinal GABAA receptors.

Science.gov (United States)

Zhao, Xin; Li, Xin-Lin; Liu, Xin; Wang, Chuang; Zhou, Dong-Sheng; Ma, Qing; Zhou, Wen-Hua; Hu, Zhen-Yu

2015-12-01

Peripheral painful neuropathy is one of the most common complications in diabetes and necessitates improved treatment. Fisetin, a naturally occurring flavonoid, has been reported to exert antidepressant-like effect in previous studies. As antidepressant drugs are employed clinically to treat neuropathic pain, this work aimed to investigate whether fisetin possess beneficial effect on diabetic neuropathic pain and explore the mechanism(s). We subjected mice to diabetes by a single intraperitoneal (i.p.) injection of streptozotocin (200mg/kg), and von Frey test or Hargreaves test was used to assess mechanical allodynia or thermal hyperalgesia, respectively. Chronic treatment of diabetic mice with fisetin not only ameliorated the established symptoms of thermal hyperalgesia and mechanical allodynia, but also arrested the development of neuropathic pain when given at low doses. Although chronic fisetin administration did not impact on the symptom of hyperglycemia in diabetic mice, it reduced exacerbated oxidative stress in tissues of spinal cord, dorsal root ganglion (DRG) and sciatic verve. Furthermore, the analgesic actions of fisetin were abolished by repetitive co-treatment with the reactive oxygen species (ROS) donor tert-butyl hydroperoxide (t-BOOH), but potentiated by the ROS scavenger phenyl-N-tert-butylnitrone (PBN). Finally, acute blockade of spinal GABAA receptors by bicuculline totally counteracted such fisetin analgesia. These findings indicate that chronic fisetin treatment can delay or correct neuropathic hyperalgesia and allodynia in mice with type 1 diabetes. Mechanistically, the present fisetin analgesia may be associated with its antioxidant activity, and spinal GABAA receptors are likely rendered as downstream targets. Copyright © 2015 Elsevier Ltd. All rights reserved.