Search results for "version"

Photovoltaic Properties of a Porphyrin-Containing Polymer as Donor in Bulk Heterojunction Solar Cells With Low Energy Loss

2017

Formation, phase composition, and transformations of Langmuir-Blodgett multi- and monolayers containing Fe

1992

Mono- and multilayers of ferric stearate were formed by the Langmuir-Blodgett technique. Thermodesorption of the hydrocarbon chains results in well defined thin oxidic films. Their reduction to Fe2+ and α-Fe was followed by conversion electron Mossbauer spectroscopy. Resonance lines can be observed even if the Fe coverage is less than one monolayer.

High‐Efficiency Perovskite Solar Cells Using Molecularly Engineered, Thiophene‐Rich, Hole‐Transporting Materials: Influence of Alkyl Chain Length on …

2016

The synthesis and characterization of a series of novel small-molecule hole-transporting materials (HTMs) based on an anthra[1,2-b:4,3-b′:5,6-b′′:8,7-b′′′]tetrathiophene (ATT) core are reported. The new compounds follow an easy synthetic route and have no need of expensive purification steps. The novel HTMs are tested in perovskite solar cells and power conversion efficiencies (PCE) of up to 18.1% under 1 sun irradiation are measured. This value is comparable with the 17.8% efficiency obtained using 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene as a reference compound. Similarly, a significant quenching of the photoluminescence in the first nanosecond is observed, ind…

Experimental and DFT study of the conversion of ephedrine derivatives into oxazolidinones. Double SN2 mechanism against SN1 mechanism

2010

Sulfonation of the N-Boc derivatives of 1,2-aminoalcohols, such as ephedrine, pseudoephedrine, norephedrine, norpseudoephedrine, thiomicamine, and chloramphenicol yields a mixture of the corresponding oxazolidinones with inversion (erythro derivatives) and/or retention of configuration (threo derivatives)at C5. We suggest a competition between two mechanisms: an intramolecular SN2 process initiated by attack of the carbonyl oxygen of the Boc group to the benzylic carbon and the other one through a double SN2 process. In the erythro derivatives the first mechanism is predominant, while in the threo derivatives both mechanisms have similar energy. This hypothesis is supported by theoretical c…

Synthesis of (+)-Isoalantolactone and (+)-Isoalloalantolactone from (−)-Santonin

1992

Abstract This paper reports on the chemical conversion of (−)-santonin into (+)-isoalantolactone and (+)-isoalloalantolactone involving functionality transfer from C 6 to C 8 , refunctionalization of the ring A and the formation of the α-methylene-8 β,12-olide moiety.

On the use of multi-parameter free energy relationships: the rearrangement of (Z)-arylhydrazones of 5-amino-3-benzoyl-1,2,4-oxadiazole into (2-aryl-5…

2010

Abstract By using a multi-parameter approach (a combination of Hammett/Ingold-Yukawa-Tsuno/Fujita-Nishioka free energy relationships) the mononuclear rearrangements of heterocycles (MRH) rates for five new ortho-substituted and ten new di-, tri-, or tetra-substituted (Z)-arylhydrazones of 5-amino-3-benzoyl-1,2,4-oxadiazole into the relevant (2-aryl-5-phenyl-2H-1,2,3-triazol-4-yl)ureas (in dioxane/water and in a large range of pS+ values) have been related to the electronic and proximity effects exerted by the present substituents, also considering previous results on some mono meta- and para-substituted (Z)-arylhydrazones. In every case, excellent correlation coefficients have been calculat…

Conditioned taste aversion in rats for a threonine-deficient diet

2000

Rats avoid a diet that is deficient in one or more essential amino acids (EAAs). This phenomenon is thought to involve the development of a "learned aversion" for the sensory properties or spatial placement associated with the deficient diet. The dietary self-selection technique has been widely used to show this avoidance of the deficient diet. Because avoidance does not necessarily imply taste aversion, we used the Taste Reactivity Test initially created by Grill and Norgren (1978) to analyze the affective reactivity pattern of rats that ingested a threonine-deficient diet. The results showed that there was an increase in the aversive responses when ingesting the threonine-deficient (Thr-D…

Unsaturated fatty acid bioconversion by apple pomace enzyme system. Factors influencing the production of aroma compounds

1996

Productions of volatile compounds (hexanal and 2,4-decadienal) obtained from polyunsaturated fatty acids by action of specific apple pomace enzyme system were quantitatively improved by increasing substrate and enzyme concentrations in the reaction medium. The importance of an exogenous supply of oxygen during bioconversion was also shown. Some physico-chemical factors involved in the pomace enzyme system expression were screened. A temperature of 25°C was favourable to the bioconversion. The control of alkaline or acidic conditions in the reaction medium may orientate the reaction preferentially to the production of one or other aldehyde.

Apple pomace: An enzyme system for producing aroma compounds from polyunsaturated fatty acids

1991

This paper reports on the possibility of obtaining C-6 (hexanal) and C-10 (2,4-dedadienal) volatile aldehydes by degradation of linoleic acid (C18∶2 Δ 9–12) under the action of the intrinsic enzyme systems found in apple pomace. More aroma compounds are produced by micronization of the pomace and by adding SO2 (60 ppm) and vitamin C (500 ppm), thereby synergistically counteracting oxidation of phenolic compounds, which is a limiting factor in bioconversion.

DRUG-DRUG INTERACTIONS VIA INHIBITION OF MICROSOMAL ENZYMES INVOLVED IN METABOLISM OF EPOXIDES PRODUCED BY MICROSOMAL MONOOXYGENASE

1977

SUMMARY Benzo(a)pyrene was activated by liver microsomes to mutagens detected by the reversion of histidine dependent Salmonella typhimurium TA 1537. Using pure epoxide hydratase or epoxide hydratase inhibitors, comparing animal species with high and low epoxide hydratase activity, or inducing monooxygenase activity, it was shown that epoxide hydratase was a critical enzyme for the inactivation of these mutagens. Many clinically used drugs are metabolized to epoxides. Epoxides are not necessarily mutagenic, but since epoxide hydratase has a very low substrate specificity, such epoxides may competitively inhibit the hydration of mutagenic epoxides, as demonstrated in the present study for th…