Quantitative polymerase chain reaction using capillary electrophoresis with laser-induced fluorescence detection: Analysis of duck hepatitis B

We report an accurate and reproducible DNA quantitation method using the polymerase chain reaction (PCR). The amount of PCR product is monitored after each PCR cycle by capillary electrophoresis. To ensure accurate quantitation, a non-amplified internal standard is added to each PCR-amplified electrophoresis sample to correct for variations in injection volume. Quantitation of the sample is based on the number of cycles necessary to generate a predetermined amount of PCR product. Duck hepatitis B virus genome was used as a model in this study. The genome was quantified with a linear relationship between cycle number and logarithm of sample DNA for amounts of sample DNA between 30 and 3.1 x 10(8) copies ( r(2)>0.999). The relative standard deviation for the corrected capillary electrophoresis signal was 2.7%, while the relative standard deviation for the overall assay was 3.0%. Results from a single-blind study generated a relative error of 1.3%.     

Automerizations in benzenoid hydrocarbons. New mechanistic insights from the thermal rearrangement of benz[a]anthracene-5-13C.

Scrambling of the carbon atoms in benz[a]anthracene between positions 5 and 6 has been shown to occur at high temperatures; a mechanism involving thermal generation of a carbene is proposed.     

Thermal stability of primary amines

Tertiary-amyl amine has been decomposed in single-pulse shock-tube experiments. Rate expressions for several of the important primary steps are This leads to D(CH₃? H) – D(NH₂? H) = ?10.5 kJ and D[(CH₃)₃C? H] – D[(CH₃)₂NH₂C? H] = + 6 kJ. The present and earlier comparative rate single-pulse shock-tube data when combined with high-pressure hydrazine decomposition results-(after correcting for fall off effects through RRKM calculations) gives where k_r(…) is the recombination rate involving the appropriate radicals. This suggests that in this context amino radical behavior is analogous to that of alkyl radicals. If this agreement is exact, then Rate expressions for the primary step in the decomposition of a variety of primary amines have been computed. In the case of benzyl amine where data exist the agreement is satisfactory. The following differences in bond energies have been estimated:      

Thermal decomposition of cyclopentane and related compounds

Cyclopentane has been decomposed in comparative-rate single-pulse shock-tube experiments. The pyrolytic mechanism involves isomerization to 1-pentene and also a minor pathway leading to cyclopropane and ethylene. This is followed by the decomposition of 1-pentene and cyclopropane. The rate expressions over the temperature range of 1000°–1200° K are Details of the cyclopentane decomposition processes are considered, and it appears that if the trimethylene radical is an intermediate, then ΔH_f(trimethylene) ≤ 280 kJ/mol at 300°K.     

Tensile properties and partial alignment of polyacetylene, (CH)x,films

The tensile properties of both cis- and trans-polyacetylene, (CH)_x, were investigated in order to determine the variables that influence that ultimate extension ratio (l/l₀) of polyacetylene films. It was found that when cis-films of polyacetylene were extended in an inert (argon) atmosphere, ultimate extension ratios as high as 3.3 were obtained and with subsequent isomerization at 160–200°C under stress, a final l/l₀, of about 4 was obtained. The extension ratio is extremely sensitive to exposure to oxygen and decreases markedly after periods as short as 1 min. It appears as though crosslinking may occur in the polymer when it is exposed to air and this produces brittleness in the specimen. When (CH)_x was isomerized from cis to trans, it became brittle, even in the absence of air.     

Evidence for strongly temperature-dependent A factors in alkane decomposition and high heats of formation for alkyl radicals

The experimental data on alkane decomposition from shock-tube and radical buffer studies and radical combination from very-low-pressure pyrolysis and modulation spectroscopy are shown to be consistent. They lead to experimental A factors which decrease by factors of 10–2000 from 300° to 1100°K. Heats of formation for ethyl, isopropyl, and t-butyl radicals have been found to be 10, 10 and 20 kJ higher than currently accepted numbers from metathesis reactions.     

A simplified approach to kinetic theory of dense fluids

Time correlation functions may be related to the fluctuating force correlation function in the sub-ensemble with fixed initial particle velocity. The latter may be evaluated by following the trajectories of particle pairs in the fluid.     

Low temperature heat capacity of electrotransported scandium

The heat capacity of two scandium samples containing 1.6 and <5 ppm atomic Fe was measured from 1 to 20 K. The weighted values for γ and θ_D are: 10.340 ± 0.018 mJ/g-at. K² and 346.1 ± 0.9 K, respectively. This is the first time anyone has obtained the same heat capacity results on two different scandium samples. The iron impurity concentration appears to be critical.