Hymenobacter endophyticus sp. nov., isolated from wheat leaf tissue.

A bacterium, designated strain ZK17L-C2T, was isolated from the leaf tissues of wheat (Triticum aestivum) collected in Chengdu, Sichuan Province, PR China. It is aerobic, non-motile, Gram-negative, rod-shaped and red-to-pink in colour. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain ZK17L-C2T belonged to the genus Hymenobacter and was most closely related to Hymenobacter rigui KCTC 12533T (98.68 %) and Hymenobacter metallilatus 9PBR-2T (98.19 %). Digital DNA-DNA hybridization (dDDH) values between strain ZK17L-C2T and these two type strains were 26.6 and 26.5 %, and average nucleotide identity (ANI) values were 84.9 and 84.8 %, respectively; these values are lower than the proposed and generally accepted species boundaries for dDDH and ANI. The genomic DNA G+C content of strain ZK17L-C2T was 59.4 mol%. It can grow at pH 5.5-7.5 and 15-30 °C, which is different from the closely related type strains. The major fatty acids of strain ZK17L-C2T were iso-C15 : 0, C16 : 0 and C18 : 0. Overall, the results from biochemical, chemical taxonomy and phylogenetic analyses indicate that strain ZK17L-C2T (=CGMCC 1.19373T=KCTC 92184 T) represents a new species of the genus Hymenobacter, for which the name Hymenobacter endophyticus sp. nov. is proposed.

Theoretical mechanistic study on the reaction of CN radical with HNCN.

The mechanism for the reaction of the cyanogen radical (CN) with the cyanomidyl radical (HNCN) has been investigated theoretically. The electronic structure information of the singlet and triplet potential energy surfaces (PESs) is obtained at the B3LYP/6-311+G(3df,2p) level, and the single-point energies are refined at the CCSD(T)/6-311+G(3df,2p) level as well as by multilevel MCG3-MPWB method. The calculations show that the C atom of CN additions to middle- and end-N atoms of HNCN are two barrierless association processes leading to the energy-rich intermediates IM1 HN(CN)CN and IM2 HNCNCN, respectively, on the singlet PES. The higher barriers of the subsequent isomerization and dissociation channels from IM1 and IM2 indicate that these two intermediates, which have considerably thermodynamic and kinetic stability, are the dominant product at high pressure. While at low pressure, the most favorable product is P(2) H + NCNCN, which will be formed from both IM1 and IM2 via direct dissociation processes by the H-N bond rupture, and the secondary feasible product is P(4) HCN + (1) NCN, while P(5) HCCN + N(2) and P(6) HCNC + N(2) are the least competitive products. On the triplet PES, P(14) NCNC + HN may be a comparable competitive product at high temperature. In addition, the comparison between the mechanisms of the CN + HNCN and OH + HNCN reactions is made. The present results will enrich our understanding of the chemistry of the HNCN radical in combustion processes and interstellar space.

Self-assembled monolayers of oligosilane on the silicon (001) surface: molecular dynamics simulations.

Atomistic molecular dynamics simulations have been used to investigate the adsorption of permethyldecasilane (MS10) on the silicon (001) surface. The condition under which the self-assembled monolayer forms is examined. The properties of the well-ordered structures, including the packing patterns, the equilibrium distances between two neighboring chains, and the tilt angles, are calculated to characterize the structure of the self-assembled monolayer. The results are comparable with those obtained experimentally.

[Structure and expression analysis of cbp gene in different natural colored-cocoon strains of Bombyx mori].

Carotenoid-binding protein (CBP) is the only key protein that has been characterized to be involved in yellow cocoon coloration of the domesticated silkworm (Bombyx mori). Gene structure and mRNA expression profiles of cbp along with UV-Vis spectrum profiles of carotenoids in silk glands were investigated among twelve strains to disclose their relationship with cocoon color. Yellow cocoon strains of B. mori contained two or three cbp gene types, which had different mRNA products with a longer form acting functionally to code CBP protein and the smaller one without exon 2. The structures of cbp were different among the green cocoon strains with the mRNA product lacking exon 2. Only one cbp gene structure existed in white cocoon strains of B. mori, which produced the mRNA product free of exon 2. A newly identified intron 1 sequence of cbp gene in this study may have cocoon color-specificity among strains. The UV-Vis spectrum profiles of carotenoids in the yellow cocoon strains' silk glands were significantly different from those in the green cocoon strains and white cocoon strains.Together, it can be concluded that the gene structure and expression profile of cbp was closely linked to cocoon colors of B. mori.

A CASSCF and CASPT2 study on the excited states of s-trans-formaldazine.

The low-lying excited states of s-trans-formaldazine (H2CN-NCH2) have been investigated using the complete active space self-consistent field (CASSCF) and the multiconfigurational second-order perturbation (CASPT2) methods. The vertical excitation energies have been calculated at the state-average CASSCF and multistate CASPT2 levels employing the cc-pVTZ basis set. The photodissociation mechanisms starting from the S1 state have been determined. The lowest energy points along the seams of surface intersections have been located in both the Franck-Condon region and the N-N dissociation pathway in the S1 state. Once the system populates the S1 state, in the viewpoint of energy, the radiationless decay via S1/S0(3) conical intersection followed by the N-N bond fission in the ground-state is more favorable in comparison with the N-N dissociation process in the S1 state. A three-surface crossing region (S1/T1/T2), where the S1, T1, and T2 states intersect, was also found. However, the intersystem crossing process via S1/T1/T2 is not energetically competitive with the internal conversion via S1/S0(3).

Accurate prediction of heat of formation by combining Hartree-Fock/density functional theory calculation with linear regression correction approach.

A linear regression correction approach has been developed successfully to account for the electron correlation energy missing in Hartree-Fock calculation and to reduce the calculation errors of density functional theory. The numbers of lone-pair electrons, bonding electrons and inner layer electrons in molecules, and the number of unpaired electrons in the composing atoms in their ground states are chosen to be the most important physical descriptors to determine the correlation energy unaccounted by Hartree-Fock method or to improve the results calculated by B3LYP density functional theory method. As a demonstration, this proposed linear regression correction approach has been applied to evaluate the standard heats of formation DeltaH(f) (Theta) of 180 small-sized to medium-sized organic molecules at 298.15 K. Upon correction, the mean absolute deviation for the 150 molecules in the training set decreases from 351.0 to 4.6 kcal/mol and 360.9 to 4.6 kcal/mol for HF/6-31G(d) and HF/6-311+G(d,p) methods, respectively. For B3LYP method, the mean absolute deviations are reduced from 9.2 and 18.2 kcal/mol to 2.7 and 2.4 kcal/mol for 6-31G(d) and 6-311+G(d,p) basis sets, respectively.