scholarly journals On the deletion of inverted repeated DNA in Escherichia coli: effects of length, thermal stability, and cruciform formation in vivo.

Genetics ◽  
1991 ◽  
Vol 129 (4) ◽  
pp. 991-1005 ◽  
Author(s):  
R R Sinden ◽  
G X Zheng ◽  
R G Brankamp ◽  
K N Allen
Keyword(s):  
Thermal Stability ◽  
Current Model ◽  
Chemical Properties ◽  
Inverted Repeats ◽  
Direct Repeats ◽  
Base Pairing ◽  
The Relationship ◽  
Thermal Stability Of ◽  
Deletion Frequency

Abstract We have studied the deletion of inverted repeats cloned into the EcoRI site within the CAT gene of plasmid pBR325. A cloned inverted repeat constitutes a palindrome that includes both EcoRI sites flanking the insert. In addition, the two EcoRI sites represent direct repeats flanking a region of palindromic symmetry. A current model for deletion between direct repeats involves the formation of DNA secondary structure which may stabilize the misalignment between the direct repeats during DNA replication. Our results are consistent with this model. We have analyzed deletion frequencies for several series of inverted repeats, ranging from 42 to 106 bp, that were designed to form cruciforms at low temperatures and at low superhelical densities. We demonstrate that length, thermal stability of base pairing in the hairpin stem, and ease of cruciform formation affect the frequency of deletion. In general, longer palindromes are less stable than shorter ones. The deletion frequency may be dependent on the thermal stability of base pairing involving approximately 16-20 bp from the base of the hairpin stem. The formation of cruciforms in vivo leads to a significant increase in the deletion frequency. A kinetic model is presented to describe the relationship between the physical-chemical properties of DNA structure and the deletion of inverted repeats in living cells.

Effect of Phenylene Diamine Antioxidant on Physico-Chemical Properties of Methyl Grafted Natural Rubber Polymer Electrolytes

2017 ◽  
Vol 864 ◽  
pp. 48-53
Author(s):  
Ahmad Fairoz Aziz ◽  
Khuzaimah Nazir ◽  
S.F. Ayub ◽  
N.I. Adam ◽  
Muhd Zu Azhan Yahya ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Natural Rubber ◽  
Polymer Electrolytes ◽  
Chemical Properties ◽  
Physico Chemical ◽  
Solution Cast ◽  
Deconvolution Techniques ◽  
Tga And Dsc ◽  
Thermal Stability Of ◽  
Aging Factor

0.5 wt.% of N-(1,3-dimethylbutyl)-N’-phenyl-p-phenylenediamine (6PPD) was introduced into polymer electrolytes based on 30% poly(methyl-methacrylate) grafted natural rubber (MG30) in order to reduce the aging factor of MG30. The polymer electrolyte without 6PPD was used as control. All samples were prepared by using solution cast techniques. The effect of 6PPD in the electrolytes was analysed by using TGA, DSC and FTIR. TGA and DSC results revealed the thermal stability of MG30 electrolytes with 6PPD have higher thermal stability but lower glass transition temperature value. FTIR studies confirmed the existence of LiTF in the sample and prove the occurrence of polymer-salt complexation. Deconvolution techniques analysis on FTIR spectra shows the electrolyte sample with 6PPD display more ion dissociation which reflects to higher ionic conductivity.

Synthese und Eigenschaften von Alkyloxi-und Aryloxi-substituierten Trithiadiborolanen / Synthesis and Properties of Alkoxi and Aryloxi Substituted Trithiadiborolanes

1981 ◽  
Vol 36 (11) ◽  
pp. 1444-1450 ◽  
Author(s):  
Max Schmidt ◽  
Erich Sametschek
Keyword(s):  
Thermal Stability ◽  
Nmr Spectra ◽  
Chemical Properties ◽  
Physical And Chemical Properties ◽  
H Nmr ◽  
New Compounds ◽  
Physical And Chemical ◽  
Thermal Stability Of ◽  
And Chemical Properties

Abstract The first examples of the hitherto unknown 1,2,4-Trithia-3,5-diborolanes with B-O-C-bonds have been synthesized and characterised. The diiodo substituted ring (2) reacts with 2,6-dimethylphenol, to form 3,5-bis-(2,6-dimethylphenyloxi)-1,2,4-trithia-3,5-di-borolane (3) and HI. 3,5-Diethoxi-1,2,4-trithia-3,5-diborolane, 5, and C2H5I are formed via the cleavage of diethylether by 2. From 2 and diisopropylether, the corresponding 3,5-diisopropyloxi-1,2,4-trithia-3,5-diborolane (6) is formed. The unsymmetrical ethers methyl-t-butylether and methylphenylether undergo reactions with 2 resulting in the formation of 3,5-dimethyloxi-1,2,4-trithia-3,5-diborolane (8) (besides t-C4H9I) and 3,5-diphenyloxi-1,2,4-trithia-3,5-diborolane (10) (besides CH3I). The thermal stability of the new compounds is increasing with increasing size of R in the -OR group and from aliphatic to aromatic R in this group. IR, Raman, 1H NMR and 11B NMR spectra of the compounds are reported as well as some physical and chemical properties.

Effect of Mg Content on Thermal Stability of β-Tricalcium Phosphate Ceramics

2014 ◽  
Vol 604 ◽  
pp. 192-195 ◽  
Author(s):  
Kristine Salma-Ancane ◽  
Liga Stipniece ◽  
Zilgma Irbe ◽  
Marina Sokolova ◽  
Guna Krieke ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Chemical Composition ◽  
Tricalcium Phosphate ◽  
Chemical Properties ◽  
Precipitation Method ◽  
Sintering Behavior ◽  
Remarkable Effect ◽  
Mg Content ◽  
Thermal Stability Of

β-Tricalcium phosphate bioceramics with small, close to bone-like amounts of Mg were obtained by modified precipitation method and following sintering. The effect of small amounts of Mg on the thermal stability, microstructure and sintering behavior of β-tricalcium phosphate bioceramics was evaluated. Addition of small amounts of Mg, can induce a remarkable effect on the physic-chemical properties of β-TCP and therefore the chemical composition of the starting materials should be controlled.

scholarly journals Investigation of the Relationship between the Residual Moisture and Thermal Stability of Lyophilized MMR Vaccine

2009 ◽  
Vol 3 (1) ◽  
pp. 25-28 ◽  
Author(s):  
MK Shahkarami ◽  
M Taqavian ◽  
A Shafyi ◽  
B Alirezaie ◽  
F Esna-ashari ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Mmr Vaccine ◽  
Residual Moisture ◽  
The Relationship ◽  
Thermal Stability Of

scholarly journals Fuel Deposit Characteristics at Low Velocity

1985 ◽  
Author(s):  
E. J. Szetela ◽  
A. J. Giovanetti ◽  
S. Cohen
Keyword(s):  
Thermal Stability ◽  
Operating Time ◽  
Test Tube ◽  
Experimental Program ◽  
Fuel System ◽  
Low Velocity ◽  
Steel Tubes ◽  
The Relationship ◽  
Thermal Stability Of

An experimental program has been carried out to characterize the relationship between deposit mass, operating time and temperature in studies of the thermal stability of aviation gas turbine fuel. This information is required by fuel system designers to prevent deposit build-up in fuel system components, thus allowing for more efficient designs. The program has included the design, fabrication, and operation of a novel thermal stability test apparatus for the determination of deposition rates over a range of temperatures and test durations up to several hundred hours. Experiments were run to determine the rate of deposit formation as a function of temperature in heated stainless steel tubes at low velocity using Jet A fuel. The test tube had an inside diameter of 0.22 cm, a length of 0.91 m, and a flow rate of 0.73 kg/hr. Deposits obtained were often characterized as thick, porous, and non-uniform in nature. Deposit density, based on carbon content was 0.08 g/cm3. Deposit rates of 0.1 to 100 μgC/hr-cm2 were observed at surface temperatures between 400 and 600 K.

Effects of glycine betaine and glycerophosphocholine on thermal stability of ribonuclease

1998 ◽  
Vol 274 (4) ◽  
pp. F762-F765 ◽  
Author(s):  
Maurice B. Burg ◽  
Eugenia M. Peters
Keyword(s):  
Thermal Stability ◽  
Tissue Culture ◽  
Glycine Betaine ◽  
Metabolic Cost ◽  
Rnase A ◽  
Renal Cells ◽  
And Function ◽  
Thermal Stability Of

Urea in renal medullas is sufficiently high to perturb macromolecules, yet the cells survive and function. The counteracting osmolytes hypothesis holds that methylamines, such as glycine betaine (betaine) and glycerophosphocholine (GPC) in renal medullas, stabilize macromolecules and oppose the effects of urea. Although betaine counteracts effects of urea on macromolecules in vitro and protects renal cells from urea in tissue culture, renal cells accumulate GPC rather than betaine in response to high urea both in vivo and in tissue culture. A proposed explanation is that GPC counteracts urea more effectively than betaine. However, we previously found GPC slightly less effective than betaine in counteracting inhibition of pyruvate kinase activity by urea. To test another macromolecule, we now compare GPC and betaine in counteracting reduction of the thermal stability of RNase A by urea. We find that urea decreases the thermal transition temperature and that betaine and GPC increase it, counteracting urea approximately equally. Therefore, the preference for GPC in response to high urea presumably has some other basis, such as a lower metabolic cost of GPC accumulation.

Sign in / Sign up

Export Citation Format

Share Document