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tert-Butanol

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Journal Article
Journal Article

Simultaneous multiagent hyperpolarized (13) C perfusion imaging

Authors: von Morze, C; Bok, RA; Reed, GD; Ardenkjaer-Larsen, JH; Kurhanewicz, J; Vigneron, DB (In Press) HERO ID: 2325070

[Less] PURPOSE: To demonstrate simultaneous hyperpolarization and imaging of three (13) C-labeled . . . [More] PURPOSE: To demonstrate simultaneous hyperpolarization and imaging of three (13) C-labeled perfusion MRI contrast agents with dissimilar molecular structures ([(13) C]urea, [(13) C]hydroxymethyl cyclopropane, and [(13) C]t-butanol) and correspondingly variable chemical shifts and physiological characteristics, and to exploit their varying diffusibility for simultaneous measurement of vascular permeability and perfusion in initial preclinical studies.

METHODS: Rapid and efficient dynamic multislice imaging was enabled by a novel pulse sequence incorporating balanced steady state free precession excitation and spectral-spatial readout by multiband frequency encoding, designed for the wide, regular spectral separation of these compounds. We exploited the varying bilayer permeability of these tracers to quantify vascular permeability and perfusion parameters simultaneously, using perfusion modeling methods that were investigated in simulations. "Tripolarized" perfusion MRI methods were applied to initial preclinical studies with differential conditions of vascular permeability, in normal mouse tissues and advanced transgenic mouse prostate tumors.

RESULTS: Dynamic imaging revealed clear differences among the individual tracer distributions. Computed permeability maps demonstrated differential permeability of brain tissue among the tracers, and tumor perfusion and permeability were both elevated over values expected for normal tissues.

CONCLUSION: Tripolarized perfusion MRI provides new molecular imaging measures for specifically monitoring permeability, perfusion, and transport simultaneously in vivo. Magn Reson Med, 2013. © 2013 Wiley Periodicals, Inc.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Antioxidant and antifungal activities of Smilax campestris Griseb. (Smilacaceae)

Authors: Morais, MI; Pinto, ME; Araújo, SG; Castro, AH; Duarte-Almeida, JM; Rosa, LH; Rosa, CA; Johann, S; Lima, LA (In Press) HERO ID: 2325014

[Less] Ethanol extract and fractions obtained from aerial parts of Smilax campestris were examined in order . . . [More] Ethanol extract and fractions obtained from aerial parts of Smilax campestris were examined in order to determine their phenolic composition, antioxidant capacity and antifungal activities. High-performance liquid chromatography coupled with DAD analysis indicated that quercetin and rutin were the main phenolic compounds present in butanol fraction and ethanol extract, respectively. The antioxidant activity assessed by the scavenging ability on 1,1-diphenyl-2-picrylhydrazyl radical was significantly more pronounced for the ethanol extract and butanol fraction than that of the commercial antioxidant 2,6-di-tert-butyl-4-methylphenol. The antifungal activity of extract and fractions was investigated by using microdilution method against five Candida and two Cryptococcus yeast strains. Ethanol extract and fractions exhibited antifungal activities against Candida albicans, Candida glabrata, Candida krusei, Candida parapsilosis, Candida tropicalis and Cryptococcus gattii. This work provides the knowledge of profile and content of flavonoids and their antioxidant and antifungal activities in the extract and fractions of aerial parts of S. campestris.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Asymmetric Allylation of Ketones and Subsequent Tandem Reactions Catalyzed by a Novel Polymer-Supported Titanium-BINOLate Complex

Authors: Yadav, J; Stanton, GR; Fan, X; Robinson, JR; Schelter, EJ; Walsh, PJ; Pericas, MA (In Press) HERO ID: 2325016

[Less] By using a novel, simple, and convenient synthetic route, enantiopure 6-ethynyl-BINOL (BINOL=1,1-binaphthol) . . . [More] By using a novel, simple, and convenient synthetic route, enantiopure 6-ethynyl-BINOL (BINOL=1,1-binaphthol) was synthesized and anchored to an azidomethylpolystyrene resin through a copper-catalyzed alkyne-azide cycloaddition (CuAAC) reaction. The polystyrene (PS)-supported BINOL ligand was converted into its diisopropoxytitanium derivative in situ and used as a heterogeneous catalyst in the asymmetric allylation of ketones. The catalyst showed good activity and excellent enantioselectivity, typically matching the results obtained in the corresponding homogeneous reaction. The allylation reaction mixture could be submitted to epoxidation by simple treatment with tert-butyl hydroperoxide (TBHP), and the tandem asymmetric allylation epoxidation process led to a highly enantioenriched epoxy alcohol with two adjacent quaternary centers as a single diastereomer. A tandem asymmetric allylation/Pauson-Khand reaction was also performed, involving simple treatment of the allylation reaction mixture with Co2 (CO)8 /N-methyl morpholine N-oxide. This cascade process resulted in the formation of two diastereomeric tricyclic enones in high yields and enantioselectivities.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Regio- and Stereoselectivity in the Reactions of Organometallic Reagents with an Electron-Deficient and an Electron-Rich Vinyloxirane: Applications for Sequential Bis-Allylic Substitution Reactions in the Generation of Vicinal Stereogenic Centers

Authors: Dieter, RK; Huang, Y; Guo, F (In Press) Journal of Organic Chemistry. HERO ID: 1070851

[Less] Vinyloxiranes provide opportunities for bis-allylic substitution reactions and the generation of new . . . [More] Vinyloxiranes provide opportunities for bis-allylic substitution reactions and the generation of new vicinal stereogenic centers if regio- and stereocontrol can be achieved. Ethyl (E)-4,5-epoxy-2-hexenoate affords excellent S(N)2':S(N)2 regioselectivity and anti:syn product diastereoselectivity with dialkyzinc reagents in the presence of CuCN, and conversion of the resultant allylic alcohol to the acetate affords good syn:anti product diastereoselectivity in S(N)2'-selective allylic substitutions with alkylcyanocuprates in THF. (E)-1-(tert-Butyldimethylsilyloxy)-2,3-epoxy-4-hexenonate gives excellent S(N)2':S(N)2 regioselectivity and anti:syn product diastereoselectivity with dialkyzinc reagents in THF or DMF or Grignard reagents in Et(2)O/THF (10/1) in the presence of CuCN. Conversion of the product allylic alcohol into the allylic phosphate affords excellent S(N)2' regioselectivity and syn:anti product diastereoselectivity with lithium alkylcyanocuprates for primary and secondary alkyl transferable ligands, while S(N)2 regioselectivity is observed for the tert-butyl ligand. Reaction conditions have been developed for regio- and stereocontrolled bis-allylic substitution reactions on both electron-rich and electron-deficient alkenyloxiranes, providing a methodology for the generation of vicinal alkane stereogenic centers.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

The formation of amyloid-like fibrils of α-chymotrypsin in different aqueous organic solvents

Authors: Simona, LM; Laczkób, I; Demcsáka, A; Tótha, D; Kotormán, M; Fülöp, L (In Press) Protein and peptide letters. HERO ID: 1039177

[Less] The formation of amyloid-like fibrils of α-chymotrypsin was studied in aqueous ethanol, methanol, tert-butanol, . . . [More] The formation of amyloid-like fibrils of α-chymotrypsin was studied in aqueous ethanol, methanol, tert-butanol, dimethylformamide and acetonitrile. Thioflavin T (ThT), Congo red (CR) and 1-anilino-8-naphthalenesulfonic acid (ANS) binding, turbidity, intrinsic fluorescence and far-UV circular dichroism measurements were employed to characterize the amyloid fibril formation. The greatest extent of fibril formation after incubation for 24 h at pH 7.0 and at 24 °C was in ethanol at 55%, in methanol and dimethylformamide (DMF) at 60-70% and in tert-butanol at 60-80%. The ANS binding and intrinsic fluorescence results showed that the hydrophobic residues are more solvent-exposed in the aggregated form of α-chymotrypsin. The ThT, CR binding and far-UV CD measurements indicated that the formation of the cross- structure of α-chymotrypsin depends on the polarity of the organic solvent. To determine the role of surface charges in the aggregation, chemically modified forms of α-chymotrypsin were prepared. The citraconylated and succinylated enzymes exhibited a higher and the enzyme forms modified with aliphatic aldehydes a lower propensity for aggregation. These results suggest the important role of surface charges in the aggregation of α-chymotrypsin.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Photooxidation of arsenite under 254 nm irradiation with a quantum yield higher than unity

Authors: Ryu, J; Monllor-Satoca, D; Kim, D-H; Yeo, J; Choi, W (In Press) Environmental Science and Technology. HERO ID: 1797795

[Less] Arsenite (As(III)) in water was demonstrated to be efficiently oxidized to arsenate (As(V)) under 254 . . . [More] Arsenite (As(III)) in water was demonstrated to be efficiently oxidized to arsenate (As(V)) under 254 nm UV irradiation without needing any chemical reagents. Although the molar absorption coefficient of As(III) at 254 nm is very low (2.49±0.1 M(-1)cm(-1)), the photooxidation proceeded with a quantum yield over 1.0, which implies a chain of propagating oxidation cycles. The rate of As(III) photooxidation was highly enhanced in the presence of dissolved oxygen, which can be ascribed to its dual role as an electron acceptor of photo-excited As(III) and a precursor of oxidizing radicals. The in-situ production of H2O2 was observed during the photooxidation of As(III) and its subsequent photolysis under UV irradiation produced OH radicals. The addition of tert-butyl alcohol as OH radical scavengers significantly reduced (but not completely inhibited) the oxidation rate, which indicates that OH radicals as well as superoxide serve as an oxidant of As(III). Superoxide, H2O2, and OH radicals were all in situ generated from the irradiated solution of As(III) in the presence of dissolved O2 and their subsequent reactions with As(III) induce the regeneration of some oxidants, which makes the overall quantum yield higher than 1. The homogeneous photolysis of arsenite under 254 nm irradiation can be also proposed as a new method of generating OH radicals.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Halide-specific enhancement of photodegradation for sulfadiazine in estuarine waters: Roles of halogen radicals and main water constituents

Authors: Zhao, Q; Fang, Q; Liu, H; Li, Y; Cui, H; Zhang, B; Tian, S (2019) HERO ID: 5343827

[Less] Although photochemical transformation is a major degradation pathway for antibiotics in surface freshwaters, . . . [More] Although photochemical transformation is a major degradation pathway for antibiotics in surface freshwaters, the photodegradation of antibiotics from freshwaters downstream into seawater is largely unknown. Herein, sulfadiazine was adopted as a representative antibiotic to probe the alteration of photolytic kinetics along freshwater to seawater sampled from Qinzhou Bay, China. The results showed that the photodegradation rate constants of sulfadiazine significantly increased in estuarine waters along freshwaters to seawaters. Experiments in synthetic water samples with isolated local dissolved organic matter (IL-DOM) indicated that the increased photodegradation of sulfadiazine is attributed to the integrative effect of both IL-DOM and halide ions. Radical quenching experiments with tert-butanol (quenching of ·OH) and isopropanol (quenching of both ·OH and reactive halogen species, RHS) demonstrated that RHS are largely responsible for the halide-specific enhancement in the photodegradation of sulfadiazine, rather than other reactive species, such as triplet-excited IL-DOM and ·OH. However, triplet-excited IL-DOM was involved in the production of RHS by the oxidation of halide ions by the triplet-excited states. Experiments conducted with DOM analogues verified DOM-sensitized RHS formation, and the degradation induced by RHS is positively correlated with the triplet-excited reduction potentials of DOM analogues. These findings are helpful in deeply understanding the transformation of antibiotics, and demonstrate the importance of RHS-induced degradation in antibiotics fate models in estuarine water systems.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Social microbial inocula confer functional stability in a methyl tert-butyl ether extractive membrane biofilm bioreactor

Authors: Purswani, J; Guisado, IM; Coello-Cabezas, J; González-López, J; Pozo, C (2019) HERO ID: 5348648

[Less] Methyl tert-butyl ether (MTBE) degradation technologies based on two-phase partitioning systems such . . . [More] Methyl tert-butyl ether (MTBE) degradation technologies based on two-phase partitioning systems such as extractive membrane biofilm reactors (EMBFR) permit separation of biological and contaminant compartments, thus allowing optimization of the biological section. In this study, we set-up an EMBFR with three MTBE-degrading and cooperating strains (termed social biofilm: Agrobacterium sp. MS2, Paenibacillus etheri SH7T and Rhodococcus ruber EE6). The removal efficiency of the social-biofilm EMBFR was 80%, and functional stability was observed in the reactor, i.e. more efficient than previous studies (single-strain inoculated EMBFR, <50% removal efficiency and unstable function). Metabolite tert-butyl alcohol was not observed, and the EC50 values were higher than those observed in single-strain EMBFRs. Comparative analysis of the MTBE enzymatic pathway and the social-biofilm was performed, where the mechanism of cooperation observed within the social-biofilm is likely due to enzymatic redundancy. Functional outcomes were equal to previous batch tests, hence 100% scalability was obtained. Overall, higher functional and stability outcomes are obtained with the use of the social-biofilm in an MTBE-EMBFR.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Histopathology re-examination of the NTP toxicity/carcinogenicity studies of tert-butyl alcohol to identify renal tumor and toxicity modes of action

Authors: Hard, GC; Cohen, SM; Ma, J; Yu, F; Arnold, LL; Banton, MI (2019) Regulatory Toxicology and Pharmacology 102:65-73. HERO ID: 5343805

[Less] Tert-butyl alcohol (TBA) targets the rat kidney following repeated exposures, including renal tubule . . . [More] Tert-butyl alcohol (TBA) targets the rat kidney following repeated exposures, including renal tubule tumors. The mode of action (MOA) of these tumors, concluded by a pathology working group, involves both alpha2u-globulin nephropathy (α2u-gN) and exacerbated chronic progressive nephropathy (CPN), but has been disputed and an undefined MOA proposed. This study further reviews the histology slides of male and female rat kidneys from the NTP drinking water 13-week toxicity and 2-year carcinogenicity studies, including the 15-month interim sacrifice group. The papillary epithelial lining alteration formerly referred to as "transitional cell hyperplasia" develops as part of advanced CPN and does not represent a separate toxicity. No changes were observed in the kidney pelvis urothelium. The only alterations in subchronic male rats involved α2u-gN and CPN, without test article-related alterations in females. Focused examination of areas of parenchyma unaffected by CPN in TBA-treated male and female rats of the chronic studies revealed no renal tubule abnormalities other than from the effects of α2u-gN and CPN. Unrelated to toxicity were spontaneous amphophilic or vacuolar tubule proliferative lesions. All observed TBA-associated non-neoplastic and neoplastic histopathological changes in the kidney can be explained by α2u-gN or enhanced CPN, neither of which are relevant to humans.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Ethyl tert-butyl ether (EtBE) degradation by an algal-bacterial culture obtained from contaminated groundwater

Authors: van der Waals, MJ; Plugge, C; Meima-Franke, M; de Waard, P; Bodelier, PLE; Smidt, H; Gerritse, J (2019) Water Research 148:314-323. HERO ID: 5343872

[Less] EtBE is a fuel oxygenate that is synthesized from (bio)ethanol and fossil-based isobutylene, and replaces . . . [More] EtBE is a fuel oxygenate that is synthesized from (bio)ethanol and fossil-based isobutylene, and replaces the fossil-based MtBE. Biodegradation of EtBE to harmless metabolites or end products can reduce the environmental and human health risks after accidental release. In this study, an algal-bacterial culture enriched from contaminated groundwater was used to (i) assess the potential for EtBE degradation, (ii) resolve the EtBE degradation pathway and (iii) characterize the phylogenetic composition of the bacterial community involved in EtBE degradation in contaminated groundwater. In an unamended microcosm, algal growth was observed after eight weeks when exposed to a day-night light cycle. In the fed-batch reactor, oxygen produced by the algae Scenedesmus and Chlorella was used by bacteria to degrade 50 μM EtBE replenishments with a cumulative total of 1250 μM in a day/night cycle (650 lux), over a period of 913 days. The microbial community in the fed-batch reactor degraded EtBE, using a P450 monooxygenase and 2-hydroxyisobutyryl-CoA mutase, to tert-butyl alcohol (TBA), ethanol and CO2 as determined using 13C nuclear magnetic resonance spectroscopy (NMR) and gas chromatography. Stable isotope probing (SIP) with 13C6 labeled EtBE in a fed-batch vessel showed no significant difference in community profiles of the 13C and 12C enriched DNA fractions, with representatives of the families Halomonadaceae, Shewanellaceae, Rhodocyclaceae, Oxalobacteraceae, Comamonadaceae, Sphingomonadaceae, Hyphomicrobiaceae, Candidatus Moranbacteria, Omnitrophica, Anaerolineaceae, Nocardiaceae, and Blastocatellaceae. This is the first study describing micro-oxic degradation of EtBE by an algal-bacterial culture. This algal-bacterial culture has advantages compared with conventional aerobic treatments: (i) a lower risk of EtBE evaporation and (ii) no need for external oxygen supply in the presence of light. This study provides novel leads towards future possibilities to implement algal-bacterial consortia in field-scale groundwater or wastewater treatment.