نتایج جستجو برای: fluorinated hydrocarbons
تعداد نتایج: 30992 فیلتر نتایج به سال:
A significant proportion of pharmaceuticals are fluorinated and selecting the site of fluorine incorporation can be an important beneficial part a drug development process. Here we describe initial experiments aimed at the development of a general method of selecting optimum sites on pro-drug molecules for fluorination, so that metabolic stability may be improved. Several model biphenyl derivat...
The mevalonate pathway is essential for the production of many important molecules in lipid biosynthesis. Inhibition of this pathway is the mechanism of statin cholesterol-lowering drugs, as well as the target of drugs to treat osteoporosis, to combat parasites, and to inhibit tumor cell growth. Unlike the human mevalonate pathway, the bacterial pathway appears to be regulated by diphosphomeval...
Substitution of leucine residues by 5,5,5-trifluoroleucine at the d-positions of the leucine zipper peptide GCN4-p1d increases the thermal stability of the coiled-coil structure. The midpoint thermal unfolding temperature of the fluorinated peptide is elevated by 13 degrees C at 30 microM peptide concentration. The modified peptide is more resistant to chaotropic denaturants, and the free energ...
Vapour thermolysis processes of copper(I1) bis-chelate complexes with different p-diketones in the 160640°C temperature range were studied by using the high-temperature source of a molecular beam with mass spectrometric recording of the gas phase composition directly at the outlet from the thermal reactor. Schemes of a heterogeneous decomposition of these compounds vapour were suggested on the ...
The incidence of congenital heart block (CHB) in the offspring of anti-Ro-positive women is approximately 1-2%, and the risk of recurrence is 10 times higher in the following pregnancies. Non-fluorinated steroids (prednisone, prednisolone and methylprednisolone) are recommended only for maternal indications, not for prevention of CHB in anti-Ro/SSA-positive women. Fluorinated steroids (dexameth...
The separation and characterization of octylphenol ethoxylate surfactants were carried out by reversed-phase high-performance liquid chromatography on branched fluorinated silica gel columns. For Triton X-100, simultaneous separation of octylphenol ethoxylate oligomers, positional isomers of octylphenyl group and butylphenol ethoxylate oligomers was achieved. These oligomers were completely sep...
The known procedures for the conversion of alkenylstannanes into the corresponding fluoroalkenes suffer from largely variable yields and a limited compatibility with functional groups; most notably, protodestannation becomes a serious issue whenever protic sites are present in the substrate. Outlined in this paper is a convenient alternative with a much improved application profile, which is la...
Property tuning by fluorination is very effective for a number of purposes, and currently increasingly investigated for aliphatic compounds. An important application is lipophilicity (log P) modulation. However, the determination of log P is cumbersome for non-UV-active compounds. A new variation of the shake-flask log P determination method is presented, enabling the measurement of log P for f...
Pellicles for Photolithography: Mechanistic Investigation of the Deep UV Photolysis of Fluorocarbons
The advance of 157 nm as the next photolithographic wavelength has created a need to for transparent and radiation durable polymers for the use as pellicles. The most promising materials for the pellicles are fluorinated polymers, but the currently available fluorinated polymers undergo photodegradation and/or photodarkening upon exposure to 157 nm irradiation. To understand the mechanism of th...
Pyrolysis and/or piranha treatment of fluorinated /ozonated single-walled carbon nanotubes (SWNTs) were found to have cut the nanotubes to short length (~100nm). Pyrolysis of partially fluorinated SWNTs (~C5F) at 700°C cut the nanotubes without causing significant crosslinking among the SWNTs. When pyrolyzed at lower temperatures, the fluorinated SWNTs need room temperature piranha treatment to...
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