Transition state of guanine N7 methylation site by Me2SO4.
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•Methylation of DNA bases.•Density functional theory and SM8 universal solvation model.•Dimethyl sulfate and SN2 ...mechanism.•Solvent effects and steric interference.•Activation energies and hydrogen bonding.
The SN2 transition states of the methylation reaction of DNA bases with dimethyl sulfate were examined employing DFT/ M06-2X/6-31+G∗ and DFT/B3LYP-D3/6-311+G (2df, 2p) levels of theory. Solvation effects were examined using the conductor-like polarizable continuum model (CPCM). Calculation results and feedback from electrostatic potential maps show that in water, charge separation lowers the activation barriers relative to the gas phase for the reactions at N7 of guanine, N3 of adenine and cytosine. Also, the reaction at the O6 site of guanine is governed by steric interference and exhibits a higher activation barrier in water.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
To provide additional normative data for the OculoMotor Assessment Tool (OMAT) for horizontal and vertical saccades and vergence jumps and to compare the results of children to adults.
Participants ...with visual acuity of logMAR ≥0.0 (6/6) and Randot stereopsis of at least 250 sec of arc without binocular disorders were recruited. Horizontal and vertical saccades, near point of convergence (NPC), accommodation and vergence jumps were evaluated using the OMAT. Means and standard deviations were reported for all parameters in children and adults.
A total of 52 participants (ages 9-34, mean age 17.5 ± 7.2 years) participated in this study. Statistically significant differences were found for horizontal and vertical saccades with lower mean results in children, aged 9-18 (111.5 ± 20.9 and 112.5 ± 22.7, respectively) compared to adults, aged 19-34 (131.6 ± 23.9 and 126.2 ± 24.2, respectively) (P = 0.002 and 0.04, respectively). The mean of the last 30 seconds of both horizontal and vertical saccades were statistically significantly lower in the children's group (52.5 ± 10.6 and 52.1 ± 11.3, respectively) compared to the adults (63.2 ± 10.2 and 59.3 ± 13.4, respectively) (P = 0.001 and 0.04, respectively). The normative values for horizontal and vertical saccades were 119.6 ± 23.9 and 118.1 ± 24.1 saccades per minute, respectively. NPC break and recovery were 2.3 ± 2.3cm and 3.0 ± 3.3cm, respectively. The vergence jumps assessment was 79.3 ± 21.19 movements per minute.
Normative values for the OMAT test were found in this study for children and adults. Assessment of endurance found children norms significantly lower for horizontal and vertical saccades compared to adults.
A set of optimized deposition conditions for the inner wall coating of fused silica tubes with amorphous selenium was elaborated. The method is based on the vapor transport deposition of pure ...elemental selenium on a cooled substrate held at liquid nitrogen temperatures. Morphological and structural examination of the deposited layer was performed by optical microscopy and X-ray diffraction studies. Neutron activated selenium was used to monitor the deposition pattern and its stability under high gas flows. Monte Carlo simulations allowed the estimation of the different Se species composing the amorphous phase, at the given experimental deposition conditions. The versatility of the coating method presented in this work allows for the coating of tubes of different lengths and diameters, opening the way for several applications of amorphous selenium films in various fields.
•A method for the amorphous selenium deposition on quartz tubes is proposed.•The deposition method was optimized to prevent crystallization of the amorphous phase.•The proposed technique can be applied to tubes with different radii and lengths.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Indication for a volatile element 114 Eichler, Robert; Aksenov, N. V.; Albin, Yu. V. ...
Radiochimica acta,
01/2010, Volume:
98, Issue:
3
Journal Article
The adsorption interactions of thallium and its compounds with gold and quartz surfaces were investigated. Carrier-free amounts of thallium were produced in nuclear fusion reactions of alpha ...particles with thick gold targets. The method chosen for the studies was gas thermochromatography and varying the redox potential of the carrier gases. It was observed that thallium is extremely sensitive to trace amounts of oxygen and water, and can even be oxidized by the hydroxyl groups located on the quartz surface. The experiments on a quartz surface with O
, He, H
gas in addition with water revealed the formation and deposition of only one thallium species – TlOH. The adsorption enthalpy was determined to be Δ
(TlOH) = −134 ± 5 kJ mol
. A series of experiments using gold as stationary surface and different carrier gases resulted in the detection of two thallium species – metallic Tl (H
as carrier gas) and TlOH (O
, O
+H
O and H
+H
O as pure carrier gas or carrier gas mixture) with Δ
(Tl) = −270 ± 10 kJ mol
and Δ
(TlOH) = −146 ± 3 kJ mol
. These data demonstrate a weak interaction of TlOH with both quartz and gold surfaces. The data represent important information for the design of future experiments with the heavier homologue of Tl in group 13 of the periodic table – element 113 (E113).
Lassa virus glycoprotein is synthesized as precursor GP-C into the lumen of the endoplasmic reticulum and cleaved posttranslationally into the N-terminal subunit GP-1 and the C-terminal subunit GP-2 ...by subtilase SKI-1/S1P. The N-terminal portion of the primary translation product preGP-C contains a signal peptide of unknown length. In order to demonstrate the signal peptide cleavage site, purified viral GP-1 isolated from Lassa virus particles was N-terminally sequenced as TSLYKGV, identical to amino acids 59–65 of GP-C. Mutational analysis of the amino acid residues flanking the putative cleavage site led to non-cleavable preGP-C indicating that no other signal peptide cleavage site exists. Interestingly, GP-C mutants with a non-cleavable signal peptide were not further processed by SKI-1/S1P. This observation suggests that the signal peptide cleavage is necessary for GP-C maturation and hence for Lassa virus replication.
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BFBNIB, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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