Complex formation of small rings with chlorine at low temperatures

1974 ◽  
Vol 15 (3) ◽  
pp. 384-387
Author(s):  
V. T. Aleksanyan ◽  
B. Z. Gevorkyan
Keyword(s):  
Complex Formation ◽  
Low Temperatures

scholarly journals Temperature-dependence of open-complex formation at two Escherichia coli promoters with extended −10 sequences

1996 ◽  
Vol 317 (1) ◽  
pp. 305-311 ◽  
Author(s):  
Helen D. BURNS ◽  
Tamara A. BELYAEVA ◽  
Stephen J. W. BUSBY ◽  
Stephen D. MINCHIN
Keyword(s):  
Escherichia Coli ◽  
Low Temperature ◽  
Complex Formation ◽  
Temperature Dependence ◽  
Low Temperatures ◽  
Dna Fragments ◽  
Promoter Sequences ◽  
E Coli ◽  
Base Sequences ◽  
Open Complex Formation

We have studied the formation of open complexes between purified RNA polymerase from Escherichia coli and DNA fragments carrying the galP1 promoter, a promoter with an extended -10 region. Unusually, these complexes are formed readily at low temperatures. This low-temperature opening is unaffected by deletions of either upstream or downstream promoter sequences. We conclude that low-temperature open-complex formation is due to specific base sequences in and just upstream of the extended -10 region. In contrast, open complexes are not formed at low temperatures with DNA fragments carrying the E. coli cysG promoter, which also has an extended -10 region. This demonstrates that an extended -10 sequence alone is not sufficient for low-temperature opening. Additionally, we report the temperature dependence of a hybrid galP1–cysG promoter, the related galP2 and galP3 promoters and a derivative of galP1 with an improved -10 hexamer sequence.

The Reaction of 2,4,6-Trinitrotoluene and 2,4,6-Trinitrotoluene-d3 with Sodium Isopropoxide in Isopropyl Alcohol

1974 ◽  
Vol 52 (9) ◽  
pp. 1750-1759 ◽  
Author(s):  
E. Buncel ◽  
A. R. Norris ◽  
K. E. Russell ◽  
P. Sheridan ◽  
H. Wilson
Keyword(s):  
Complex Formation ◽  
Low Temperatures ◽  
Isopropyl Alcohol ◽  
Initial Rate ◽  
Ion Pairs ◽  
Stopped Flow ◽  
Rate Data ◽  
Methyl Group ◽  
Free Ions ◽  
Deuteron Transfer

The reaction of sodium isopropoxide with 2,4,6-trinitrotoluene (TNT) and TNT-d3 (deuterated methyl group) in isopropanol has been investigated using stopped-flow techniques. Two absorbing species, identified as a σ-complex and the TNT anion (TNT−) are formed in this reaction. The formation of TNT− involves a rate determining proton transfer as shown by the observation of an isotope effect[Formula: see text] A spectrum of the σ-complex was calculated from initial rate data and was observed experimentally at low temperatures (λmax = 435, 495 nm). The effects of added salts on rates and equilibria of σ-complex and TNT− formation have been determined.In this study the possible involvement of free alkoxide ions and ion-pairs in the reactions has been evaluated. The free alkoxide ion is the more reactive species in deuteron transfer whilst in σ-complex formation the free ions and ion-pairs have comparable reactivity. A rationale of this behavior is presented.The kinetic parameters are, for deuteron transfer: kiD = 850 ± 100 M−1s−1 at 30 °C, ΔH≠ = 14.9 ± 1.1 kcal mol−1, ΔS≠ = 5.1 ± 2.9 cal deg−1 mol−1; for σ-complex formation: k′ = 1870 ± 150 M−1 s−1 at 30 °C, ΔHσ≠ = 10.2 ± 0.3 kcal mol−1, ΔSσ≠ = −9.8 ± 1.1 cal deg−1 mol−1.

Kinetic Competition During Solid Phase Crystallization in Ion–Implanted Silicon

1983 ◽  
Vol 23 ◽  
Author(s):  
G.L. Olson ◽  
J.A. Roth ◽  
L.D. Hess ◽  
J. Narayan
Keyword(s):  
Complex Formation ◽  
Low Temperatures ◽  
Solid Phase ◽  
Solid Phase Epitaxy ◽  
Solid Phase Crystallization ◽  
Competing Interactions ◽  
Cross Sectional ◽  
Time Resolved ◽  
Vacancy Model ◽  
Dominant Process

ABSTRACTWe report on an investigation of the temperature and concentration dependent kinetic competition between solid phase epitaxy and complex formation and precipitation in arsenic–implanted Si(100). Crystallization kinetics were monitored using time–resolved reflectivity during cw laser irradiation or furnace heating; microstructural changes were evaluated using cross–sectional TEM. At low temperatures and high As concentrations, complex formation and precipitation substantially alter the SPE kinetics. At higher temperatures competing interactions are less significant, and SPE becomes the dominant process. The kinetic competition between these processes is discussed with respect to the vacancy model for SPE.

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