So-yeon Kim

Conical intersection seam and bound resonances embedded in continuum observed in the photodissociation of thioanisole-d3

Herein, the multi-dimensional nature of the conical intersection seam has been experimentally revealed in the photodissociation reaction of thioanisole-d3 (C6H5SCD3) excited on S1, giving C6H5S·(Ã or X̃]) +·CD3 products. The translational energy distribution of the nascent·CD3 fragment, reflecting the relative yields of the C6H5S·(Ã) and C6H5S·(X̃) products, was measured at each S1 vibronic band using the velocity map ion imaging technique. Direct access of the reactant flux to the conical intersection seam leads to the increase of the nonadiabatic transition probability resulting in sharp resonances in the X̃/ÃC6H5S·product branching ratio at several distinct S1 vibronic bands. The nature of the S1 vibronic bands associated with such dynamic resonances was clarified by the mass-analyzed threshold ionization spectroscopy. The bound state embedded in continuum generated by the conical intersection is observed as a distinct dynamic resonance, revealing the nature of the nuclear motion responsible for the nonadiabatic coupling of two potential energy surfaces at the conical intersection. The multi-dimensional facets of the conical intersection seam in terms of its detailed structure and dynamic role are discussed with the aid of theoretical calculations.

Dynamic Role of the Intramolecular Hydrogen Bonding in Nonadiabatic Chemistry Revealed in the UV Photodissociation Reactions of 2-Fluorothiophenol and 2-Chlorothiophenol

The dynamic interplay between the intramolecular hydrogen bonding and intramolecular vibrational redistribution is found to be critical in nonadiabatic reaction dynamics. Herein, it has been demonstrated that the molecular planarity, directed by the intramolecular hydrogen bonding, plays an important role in the nonadiabatic passage of the reactive flux at the conical intersection in the photodissociation reactions of 2-fluorothiophenol and 2-chlorothiophenol. As the internal energy increases in the excited state, the intramolecular hydrogen bonding of 2-fluorothiophenol loosens. The floppiness brought into the molecular structure then modifies the dynamic path of the reactive flux, leading to the diminishment of the nonadiabatic transition probability at the conical intersection. On the contrary, for 2-chlorothiophenol having the relatively stronger intramolecular hydrogen bonding, the reactive flux seems to retain the molecular planarity even with the increase of the internal energy as manifested by the constant nonadiabatic transition probability over the wide range of the S1 internal energy. The effect of the intramolecular hydrogen bonding on the molecular structure and its relation to the nonadiabatic dynamics along the tunneling path has been experimentally demonstrated.

Spectroscopic Separation of the Methyl Internal-Rotational Isomers of Thioanisole Isotopomers (C6H5S-CH2D and C6H5S-CHD2)

Two distinct rotational isomers of thioanisole-d1 (C6H5S-CH2D) and thioanisole-d2 (C6H5S-CHD2) with respect to the internal rotation of the methyl moiety have been identified and characterized spectroscopically using the resonantly enhanced two photon ionization, UV-UV hole burning, and slow-electron velocity map imaging techniques. From the statistical weights, the definite assignment for the specific rotational isomer of each isotopomer has been successfully done, providing isomer-specific ionization energies and vibrational frequencies of S1/D0 states. Detailed molecular structures, the methyl internal-rotor barrier, and normal-mode descriptions for selective vibrations are discussed with the aid of density functional theory calculations.

The clonal origins of leukemic progression of myelodysplasia

The genetics behind the progression of myelodysplasia to secondary acute myeloid leukemia (sAML) is poorly understood. In this study, we profiled somatic mutations and their dynamics using next generation sequencing on serial samples from a total of 124 patients, consisting of a 31 patient discovery cohort and 93 patients from two validation cohorts. Whole-exome analysis on the discovery cohort revealed that 29 of 31 patients carry mutations related to at least one of eight commonly mutated pathways in AML. Mutations in genes related to DNA methylation and splicing machinery were found in T-cell samples, which expand at the initial diagnosis of the myelodysplasia, suggesting their importance as early disease events. On the other hand, somatic variants associated with signaling pathways arise or their allelic burdens expand significantly during progression. Our results indicate a strong association between mutations in activated signaling pathways and sAML progression. Overall, we demonstrate that distinct categories of genetic lesions play roles at different stages of sAML in a generally fixed order.

H/D substitution makes difference in photochemical studies: the case of dimethylamine

When the molecule in the excited state is subject to prompt predissociation, it is quite nontrivial to obtain vibrational structure of the excited state in general. This applies to the case of photochemistry of dimethylamine (DMA:(CH3)2NH). When DMA is excited to its first electronically excited state (S1), the N-H bond dissociation occurs promptly. Therefore, S1 vibronic bands are homogeneously broadened to give extremely small ionization cross sections and heavily-congested spectral features, making infeasible any reasonable spectral assignment. Here, we demonstrate that the predissociation rate of the excited state could be significantly reduced by the NH/ND substitution to give the much better-resolved S1 spectral feature, revealing the vibrational structure of the excited state of DMA-d1 ((CH3)2ND) for the first time.

A Basic Study on Performance Evaluation of Permanent Supplementary Artificial Lighting of Interior(PSALI) using a LED Light Source

Since the first lighting light source was invented, lighting has turned into superior-quality lighting considering the amenity of occupants, and the characteristics of a light source has developed rapidly. So this research confirmed the lighting performance of a dimmer control system and an ON-OFF control system via the existing light source, and analyzed the basic lighting environment of Permanent Supplementary Artificial Lighting of Interiors(PSALI) through the physical comparison and evaluation of a LED lamp substituted for a fluorescent lamp used in a dimmer control system, showing that the lighting physical quantity characteristics of an ON-OFF control system and a dimmer control system are similar to each other and that they are effective in terms of energy saving. Besides, it was shown that introducing a LED light source to a dimmer control system improves lighting environments and largely reduces energy consumption.

Verification of Significancebetween Experiment Devices and Scaled-down Model for the Study of PSALI

PSALI is referred to the supplementary lighting for the interior lighting under the daily lighting situation, and pursuant to the pertinent regulations in energy savings design standard and others in recent architecture works, the importance thereof has been increasing gradually coupled with the energy performance index (EPI), energy savings plan and the like as well as expansion of submittal and implementation policies. However, this type of PSALI studies indeed have a number of limitations since it has surrounding environmental conditions in direction, season, region, climate, time, opening rate, window area ratio, actual index, reflection rate of finishing materials and others in the architecture work as well as frequent changes in interior lighting environment for variables in daily light volume flowing into the interior, and others. Therefore, this study has analyzed existing advance research cases to produce the actual-sized model and scaled-down model, and installed the artificial lighting of LED light source possible to reproduce with same capability on both models. As a result of comparison and analysis of the artificial lighting with the key light, it has certain level of error rate from the scaled down lighting device in certain rate and actual model butit was noticeably significant within specific scope.

The Effect of the Keughachukeo-tang Extract on the Hepatocellular Carcinogenesis and Acute Liver Damage Induced by Diethylnitrosamine and CCl 4 in Rats

This study was performed to observe the effect of Keughachukeo-tang(KH) extract on the hepatocellular carcinogenesis and acute liver damage induced by Diethylnitrosamine(DENA) and in Rats. Experimental groups were divided into four; normal group(Nor), acute liver damage and hepatocellular cancer inducing control group(Con), KH extract 350㎎/㎏/day(KHA), and 700㎎/㎏/day(KHB) administered groups to Con. The results obtained are as follows: The body weight increased in KHA and KHB than Con from 7th week to the 8th week. The activities of Alanine aminotransferase(ALT) were the most increased in the Con among experimental group. The activities of aspartate aminotransferase(AST), alkaline phosphatase(ALP), and lactacte dehydrogenase(LDH) were significantly decreased(p

Effects of Auklandia Lappa on Dextran Sulfate Sodium-Induced Murine Colitis

in Rats.