British Library Electronic Table of Contents (United Kingdom)

Uragogin and blepharodin were isolated from Crossopetalum uragoga and Maytenus magellanica, respectively. They represent the first examples of a triterpene-neolignan ester and a heptacyclic arylpropanoid-nor-triterpenephenol, hetero-Diels-Alder adducts built with dioxane bridges. Their proposed biosynthetic route is discussed.

International Nuclear Information System (INIS)

The purpose of work is systematical studying of benzo (B) of thiophene-1,1-dioxides and their 2,3-di-hydro derivatives behaviour in the reactions of electrophflic, radical, nucleophilic nitration, reduction of nitro group, embodiment of synthesis of N-amino derivatives, investigation of sulfur containing hetero-cyclic compounds, including of residues of some steroids

International Nuclear Information System (INIS)

This thesis dealt with the metal-organic gas phase epitaxy with nitrogen as carrier gas. For this first by means of three-dimensional modelings of the epitaxy process the influence of the carrier gas on the processes was explained. The optimization of the growth parameter for the whole light-emitting-diode structure in double-hetero arrangement resulted that an a temperature of 770 C and a V/ III-ratio of 150 layers with a high crystal quality could be reached.

British Library Electronic Table of Contents (United Kingdom)

SummaryPermeable pavement functions as a porous infrastructure interface allowing the infiltration and evaporation of rainfall-runoff while functioning as a relatively smooth load-bearing surface for vehicular transport. Hydraulic conductivity (k) of permeable pavement is an important hydraulic property and is a function of the pore structure. This study examines k for a cementitious permeable pavement (CPP) through a series of pore-structure models. Measurements utilized include hydraulic head as well as total porosity, (t), effective porosity (e), tortuosity (Le/L) and pore size distribution (PSD) indices generated through X-ray tomography (XRT). XRT results indicate that the permeable pavement pore matrix is hetero-disperse, with high tortuosity and t!=e. Power law models of k-t and k-e...

Energy Technology Data Exchange (ETDEWEB)

Described herein are the results of the FY1994 research program for analysis and evaluation for thin film solar cells. The study on quantitative analysis of hydrogen atoms in a plasma determines quantity of hydrogen atoms in the plasma of monosilane diluted with hydrogen. It is found, contrary to expectation, that quantity of hydrogen atoms in the plasma decreases as it is more diluted with hydrogen. The study on light-induced degradation of the thin chlorine-base amorphous silicon films confirms that the plasma CVD method with 20% of dichlorosilane gas added to monosilane gas produces the thin amorphous silicon film 3 times faster than the conventional method. The thin film has essentially the same defect density as the one prepared by the conventional method, showing good photoelectric characteristics. The thin film of chlorinated amorphous silicon has a 1 digit lower defect density than the conventional one of amorphous silicon, as revealed by the accelerated degradation test with ...

Energy Technology Data Exchange (ETDEWEB)

One of our research objectives is to develop chemistry of transition metal chalcogenides which are relevant to new inorganic materials, environmental catalysts, metalloenzymes. In this context, this research project has been aimed at rational syntheses of chalcogenide complexes of electron-deficient transition metals, construction of hetero metallic clusters with high nuclearity, and elucidation of chemical properties characteristic of these metal chalcogenide compounds. We were successful in synthesizing a series of sulfide (selenide)/thiolate complexes of group 4,5 and 6 transition metal elements by making use of C-S bond cleaving reactions and anhydrous chalcogenide reagents. We also achieved construction of unprecedented large chalcogenide clusters of mixed metal systems such as [Cu{sub 4}(dppm){sub 4}MS{sub 4}] [PF{sub 6}]{sub 2} (M=Mo, W), [(Cp*WS{sub 3}Ag{sub 2}){sub 2}({mu}-Br){sub 2}]{sub {infinity}}, and [Cp*{sub 2}Mo{sub 2}Fe{sub 2}S{sub 4}]{sub ...

Energy Technology Data Exchange (ETDEWEB)

A number of fragment ion onsets from the photoionization of CH/sub 3/SCCSCH/sub 3/ and CH/sub 3/SSSCH/sub 3/ have been measured. In addition, our experiment has been converted to a molecular beam source which will increase the precision of our measurements. Exhaustive oxidation of the divalent sulfur to sulfonic acids serves to quench the effects of quadrupolar broadening and thereby allowing for quantitative evaluation of structurally similar sulfonic acids. W/sub 1/2/ are reduced to < 25 Hz at 19 MHz (57,500 Gauss). Electronegative substituents shield the /sup 33/S nucleus perhaps imploying more efficient 2p-3d..pi.. backbonding between sulfur and oxygen. ..cap alpha..-Hetero substituents of sulfonyl groups do not influence the shift of the /sup 33/S to a dramatic extent. The exception is the dianion of thiosulfate compared to the dianion of sulfate. Lanthanide shift reagents, (Eu(fod)/sub 3/), are potentially useful in distinguishing sulfonyl /sup 17/O shifts ...

Energy Technology Data Exchange (ETDEWEB)

The scope of the present study was upgrading a set of heavy aromatic hydrocarbons mixtures whose commercial value ranks close to fuel oil and should become even lower in the next future because of the introduction of more stringent regulations on fuels, through hydro-conversion to a synthetic feed for steam-cracking. The resulting process provides an opportunity to improve the economic return of a steamcracking plant, offering the chance of converting low-value mixtures produced by the plant itself, such as fuel oil of cracking (FOK), saving an equivalent amount of naphtha. The method can also be used for converting pyrolysis gasoline (pygas). Although pygas has at present a fair commercial value, it could suffer a significant penalization in the future due to further limitations on total aromatic content in gasoline. Pygas hydro-conversion to a synthetic steam-cracking feedstock has been recently reported. Fractions from refinery, such as heavy distillates (e.g. Heavy Vacuum Gas Oil, ...