Rotational dynamics of solvated carbon dioxide studied by infrared, Raman, and time-resolved infrared spectroscopies and a molecular dynamics simulation

Rotational dynamics of solvated carbon dioxide (CO(2)) has been studied. The infrared absorption band of the antisymmetric stretch mode in acetonitrile is found to show a non-Lorentzian band shape, suggesting a non-exponential decay of the vibrational and/or rotational correlation functions. A combined method of a molecular dynamics (MD) simulation and a quantum chemical calculation well reproduces the observed band shape. The analysis suggests that the band broadening is almost purely rotational, while the contribution from the vibrational dephasing is negligibly small. The non-exponential rotational correlation decay can be explained by a simple rotor model simulation, which can treat large angle rotations of a relatively small molecule. A polarized Raman study of the symmetric stretch mode in acetonitrile gives a rotational bandwidth consistent with that obtained from the infrared analysis. A sub-picosecond time-resolved infrared absorption anisotropy measurement of the antisymmetric stretch mode in ethanol also gives a decay rate that is consistent with the observed rotational bandwidths.     

A novel total synthesis of isocryptolepine based on a microwave-assisted tandem Curtius rearrangement and aza-electrocyclic reaction

A new entry to the total synthesis of isocryptolepine (cryptosanguinolentine), isolated from Cryptolepis sanguinolenta, was achieved by constructing a tetracyclic ring system through a microwave-assisted tandem Curtius rearrangement and electrocyclic reaction of an aza 6π-electron system. The tetracyclic lactam was converted to isocryptolepine in a four-step sequence.     

Monocular viewing prolongs reversal interval of perceptual rival figure

The authors examined whether the perceptual reversal rate changes under monocular versus binocular viewing conditions. Our results suggest that the perceptual reversal interval increases during monocular viewing. The ratio of the reversal rate (1/interval) for the two viewing conditions (binocular/monocular) was 1.28 over a wide range of pattern luminance levels. The quoted ratio was 1.40 when the luminance was high. Such a ratio parallels the value of a well-known binocular summation index $(\sqrt 2 )$ , which was derived from the signal detection theory. The binocular summation index shows that the strength of an input signal is enhanced by binocular viewing. However, how the binocular summation shortens the perceptual reversal interval is unclear. This issue can be resolved if the perceptual reversal is derived by integrating the strength of an unconscious image signal. Thus, we discussed the mechanism of perceptual switch by associating two classical, well-studied phenomena, binocular summation and perceptual switch.     

The graph grabbing game on Km,n-trees

The graph grabbing game is a two-player game on weighted connected graphs where all weights are non-negative. Two players, Alice and Bob, alternately remove a non-cut vertex from the graph (i.e., the resulting graph is still connected) and get the weight assigned to the vertex, where the starting player is Alice. Each player’s aim is to maximize his/her outcome when all vertices have been taken, and Alice wins the game if she gathered at least half of the total weight. Seacrest and Seacrest (2017) proved that Alice has a winning strategy for every weighted tree with even order, and conjectured that the same statement holds for every weighted connected bipartite graph with even order. In this paper, we prove that Alice wins the game on a type of a connected bipartite graph with even order called a $K_{m,n}$-tree.     

Synthesis of PEO/4Hb-TaS2 layered nanocomposite

Single-phase layered nanocomposite containing 4Hb-TaS₂ and poly(ethylene oxide) [PEO] has been first synthesized by using the exfoliation-adsorption technique. It has been characterized by powder X-ray diffraction (XRD) and electrical dc resistivity measurements. As the product exhibited lattice expansions along the stacking direction, PEO was intercalated into 4Hb-TaS₂ galleries.     

Relationship between human IgG structure and retention time in hydroxyapatite chromatography with sodium chloride gradient elution

Accurate prediction of the elution tendency of monoclonal antibodies in column chromatography would be beneficial for the efficient setup of purification procedures. Hydroxyapatite chromatography experiments using 37 recombinant human monoclonal antibodies were performed by sodium chloride gradient elution with 5 mM sodium phosphate to correlate the retention times with antibody structures (subclass and light‐chain isotypes). The contribution of metal affinity interactions in the interaction of antibodies with hydroxyapatite was investigated by (i) eliminating 5 mM sodium phosphate in buffers, (ii) comparing sodium chloride versus sodium phosphate gradient elutions, and (iii) using IgG₄ antibodies with a leucine→glutamate mutation. By using antibodies of different subclasses but with identical Fab regions, the elution behavior in sodium chloride elution could be classified by subclass and type of light chain. It is considered that the retention of monoclonal antibodies to hydroxyapatite is affected by the cooperation of phosphoryl cation exchange and metal affinity interactions. The contribution of the metal affinity interactions is greater in the sodium chloride gradient elution method than in the sodium phosphate gradient elution method.     

Genetic and expression analysis of all non‐synonymous single nucleotide polymorphisms in the human deoxyribonuclease I‐like 1 and 2 genes

Members of the human DNase I family, DNase I‐like 1 and 2 (DNases 1L1 and 1L2), with physiological role(s) other than those of DNase I, possess three and one non‐synonymous SNPs in the genes, respectively. However, only limited population data are available, and the effect of these SNPs on the catalytic activity of the enzyme remains unknown. Genotyping of all the non‐synonymous SNPs was performed in three ethnic groups including six different populations using the PCR‐RFLP method newly developed. Asian and African groups including Japanese, Koreans, Ghanaians and Ovambos were typed as a single genotype at each SNP, but polymorphism at only SNP V122I in DNase 1L1 was found in Caucasian groups including Germans and Turks; thus a Caucasian‐specific allele was identified. The DNase 1L1 and 1L2 genes show relatively low genetic diversity with regard to these non‐synonymous SNPs. The level of activity derived from the V122I, Q170H and D227A substituted DNase 1L1 corresponding to SNPs was similar to that of the wild‐type, whereas replacement of the Asp residue at position 197 in the DNase 1L2 protein with Ala, corresponding to SNP D197A, reduced its activity greatly. Thus, SNP V122I in DNase 1L1 exhibiting polymorphism exerts no effect on the catalytic activity, and furthermore SNP D197A in DNase 1L2, affecting its catalytic activity, shows no polymorphism. These findings permit us to postulate that the non‐synonymous SNPs identified in the DNase 1L1 and 1L2 genes may exert no influence on the activity levels of DNases 1L1 and 1L2 in human populations.     

The linear arboricity of some regular graphs

We prove that the linear arboricity of every 5-regular graph is 3. That is, the edges of any 5-regular graph are covered by three linear forests. We also determine the linear arboricity of 6-regular graphs and 8-regular graphs. These results improve the known upper bounds for the linear arboricity of graphs with given maximum degree.