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tert-Butanol

3,403 References Were Found:

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

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

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

Freeze-Drying From Organic Co-Solvent Systems, Part 2: Process Modifications to Reduce Residual Solvent Levels and Improve Product Quality Attributes

Authors: Kunz, C; Schuldt-Lieb, S; Gieseler, H (2019) HERO ID: 5078536

[Less] The use of co-solvent systems can benefit the freeze-drying process and product performance. In this . . . [More] The use of co-solvent systems can benefit the freeze-drying process and product performance. In this study, cycle designs were applied based on existing recommendations for water-based formulations. Modifications thereof and the influence on the process (e.g., drying times) and product quality attributes (e.g., product appearance, residual solvent) were tested for various cosolvent systems. It was found that fast freezing was associated with the formation of large crystals for 50 mg/g polyvinylpyrrolidone in 40% 1,4-dioxane (w/w), resulting in a 7% reduction of primary drying. The application of high shelf temperatures during primary drying for 50 mg/g polyvinylpyrrolidone in 70% tert-butanol was feasible, resulting in shorter primary drying times but high residual solvent levels (7.7%). Most notable was that the inclusion of an evaporation step after freezing improved the product appearance for low-melting co-solvents (10% ethanol and 10% acetone). No ice or solvent nucleation occurred in the case of 50 mg/g mannitol in 50% N,N-dimethylacetamide during the normal freezing stage. Instead, the solution viscosity significantly increased after cooling to low shelf temperatures, followed by product evaporation (rather than sublimation) during the drying phase and failure to form a product cake after drying. The application of annealing enabled nucleation and sublimation.

Archival Material
Archival Material

NTP pathology consult for ETBE and tBA

Author: NIEHS (2019) HERO ID: 5098230


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

Self-doped TiO2 nanotube arrays for electrochemical mineralization of phenols

Authors: Gan, L; Wu, Y; Song, H; Lu, C; Zhang, S; Li, A (2019) HERO ID: 5099354

[Less] Self-doped TiO2 nanotube arrays (DNTA) were prepared for the electrooxidation of resistant organics. . . . [More] Self-doped TiO2 nanotube arrays (DNTA) were prepared for the electrooxidation of resistant organics. The anatase TiO2 NTAs had an improved carrier density and conductivity from Ti3+ doping, and the oxygen-evolution potential remained at a high value of 2.48 V versus the standard hydrogen electrode, and thus, achieved a highly enhanced removal efficiency of phenol. The second anodization could stabilize Ti3+ and improve the performance by removing surface TiO2 particles. Improper preparation parameters (i.e., a short anodization time, a high calcination temperature and cathodization current density) harmed the electrooxidation activity. Although boron-doped diamond (BDD) anodes performed best in removing phenol, DNTA exhibited a higher mineralization of phenol than Pt/Ti and BDD at 120 min because intermediates were oxidized once they are produced with DNTA. Mechanism investigations using reagents such as tert-butanol, oxalic acid, terephthalic acid, and coumarin showed that the DNTA mineralization resulted mainly from surface-bound OH, and the DNTA produced more than twice the amount of OH compared with BDD. The free OH on the BDD electrode was more conducive to initial substrate oxidation, whereas the adsorbed OH on the DNTA electrode mineralized the organics in situ. The preferential removal of p-substituted phenols on DNTA was attributed mainly to their electromigration and the aromatic intermediates that are hydrophobic were beneficial to mineralization.

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 role of fluoroalcohols as counter anions for ion-pairing reversed-phase liquid chromatography/high-resolution electrospray ionization mass spectrometry analysis of oligonucleotides

Authors: Liu, R; Ruan, Y; Liu, Z; Gong, L (2019) Rapid Communications in Mass Spectrometry 33:697-709. HERO ID: 5099481

[Less] RATIONALE: Hexafluoroisopropanol (HFIP) has been widely used as a counter anion in . . . [More] RATIONALE: Hexafluoroisopropanol (HFIP) has been widely used as a counter anion in the mobile phase for ion-pairing reversed-phase liquid chromatography/mass spectrometry (IP-RP-LC/MS) analysis of oligonucleotides. However, researchers are still searching for improvements to counter anions for LC/MS analysis of oligonucleotides. This study aimed to find alternatives to HFIP for analyzing oligonucleotides.

METHODS: The study was performed using an Agilent 1290 ultra-high-performance liquid chromatography (UHPLC) system coupled to an Agilent 6540 mass spectrometer by using an oligonucleotide BEH C18 column (100 × 2.1 mm, 1.7 μm). Buffer systems containing ion-pairing reagents (triethylamine, tripropylamine, hexylamine, dimethylbutylamine, diisopropylethylamine, N,N-dimethylcyclohexylamine, and octylamine) and fluoroalcohols (HFIP and hexafluoro-2-methyl-2-propanol (HFTP)) were compared chromatographically and mass spectrometrically.

RESULTS: Results showed that HFTP has better desalting ability than HFIP, but both HFIP and HFTP have comparable effects on the separation of oligonucleotides sized from 10mer to 40mer for most of ion-pairing reagents, with the exception of triethylamine and N,N-dimethylcyclohexylamine, where HFIP performed better than HFTP.

CONCLUSIONS: The choice of fluoroalcohols in IP-RP-LC/MS analysis of oligonucleotides depends on the type of ion-pairing reagents used in the mobile phase. As a guideline, we would recommend to use either HA-HFIP or HA-HFTP for small oligonucleotides, but TPA-HFTP for large oligonucleotides for IP-RP-LC/MS analysis of synthetic oligonucleotides.