Life on Earth is dependent on sunlight. In the process known as photosynthesis, plants,
algae and certain bacterias are capable of using this source of energy to drive the synthesis
of organic compounds. The oxygenic photosynthesis results in the release of molecular
oxygen and the removal of carbon dioxide from the atmosphere that is used to synthesize
Regioregular polythiophene-based conductive copolymers with highly crystalline nanostructures are shown to hold considerable promise as
the active layer in volatile organic compound (VOC) chemresistor sensors. While the regioregular polythiophene polymer chain provides a
charge conduction path, its chemical sensing selectivity and sensitivity can be altered either by incorporating a second polymer to form a
block copolymer or by making a random copolymer of polythiophene with different alkyl side chains.
The benzoacronycine derivative, S23906-1, was character-ized recently as a novel potent antitumor agent through
alkylation of theN2 positionof guanines inDNA.We show
here that its reactivity towards DNA can be modulated
by glutathione (GSH). The formation of covalent adducts
between GSH and S23906-1 was evidenced by EI-MS, and
the use of different GSH derivatives, amino acids and
dipeptides revealed that the cysteine thiol group is absolutely
required for complex formation because glutathione disul-fide (GSSG) and other S-blocked derivatives failed to react
covalently with S23906-1. ...
Petroleum refining operations can be separated into five basic areas: 1. Fractionation (distillation) is the separation of crude oil in atmospheric and vacuum distillation towers into different "fractions" or "cuts." 2. Conversion processes change the size and/or structure of hydrocarbon molecules. These processes include: − Decomposition by thermal and catalytic cracking; − Unification through alkylation and polymerization; − Alteration with isomerization and catalytic reforming. ...
VOC concentrations in the belly space were measured during four sampling events.
Adjusted belly concentrations were compared to average adjusted indoor concentrations (Table
3). Here the fractional differences were positive for all compounds. For a number of VOCs,
these differences were substantial (2-butanone, less volatile aldehydes, alkane hyrdrocarbons,
and aromatic hydrocarbons except styrene).
Na+-Montmorillonite (Na+-MMT) minerals were organically modified by adding different amounts of surfactant octadecylamine corresponding to the cation exchange capacity (CEC) of the pristine montmorillonites. The characteristic of the organo-MMT were obtained by X-ray diffraction, FT-IR spectroscopy. The amount of added surfactant has direct effect on the interlayer separation and the organophicility-hydrophicility balance of MMT. An optimal surfactant/CEC ratio about 1.0 leads to two distinct distance of 15.5 Å and 32.
Ketol-acid reductoisomerase (EC 220.127.116.11) is involved in the biosynthesis
of the branched-chain amino acids. It is a bifunctional enzyme that cata-lyzes two quite different reactions at a common active site; an isomeriza-tion consisting of an alkyl migration, followed by an NADPH-dependent
reduction of a 2-ketoacid. The 2-ketoacid formed by the alkyl migration
is not released. Using the pure recombinant Escherichia colienzyme, we
show that the isomerization reaction has a highly unfavourable equili-brium constant....
The binding of several alkyl- and aryl-guanidines andN-hydroxyguanidines
to the oxygenase domain of inducible NO-synthase (iNOSoxy) was studied
by UV⁄Vis difference spectroscopy. In a very general manner, monosubsti-tuted guanidines exhibited affinities for iNOSoxy that were very close to
those of the corresponding N-hydroxyguanidines. The highest affinities
were observed for the natural substrates,l-arginine and N
-hydroxy-l-arginine (Kd at thelmlevel).