Local structure around Ga in ultrafine GaN/ZnO coaxial nanorod heterostructures

The structure of tubular GaN coaxially grown on ZnO nanorods with thickness of 6-12 nm was investigated using x-ray absorption fine structure (XAFS) at the Ga K edge. The XAFS measurements revealed that the GaN had a distorted-wurtzite structure, and that there were more distortions in the bond length of Ga-Ga pairs than in Ga-N pairs. However, no extra disorders were observed in any of the pairs. These results strongly suggest that Ga atoms first bonded to the ZnO template. Unlike other techniques, the XAFS determines structure around a selected species atom in nano-heterostructures. (c) 2006 American Institute of Physics.open1188sciescopu

Orientation-dependent x-ray absorption fine structure of ZnO nanorods

The local structure of two samples of vertically well-aligned ZnO nanorods with average diameters of 13 and 37 nm were studied using orientation-dependent x-ray absorption fine structure (XAFS) at the Zn K edge. The aligned ZnO nanorod samples were fabricated on sapphire (0001) substrates with a catalyst-free metalorganic vapor-phase epitaxy method. The XAFS measurements showed that both nanorod samples have a well-ordered wurtzite structure and that no vacancy was observed at either site of zinc or oxygen atoms. However, we found that in both samples the lattice constants of a and b were shrunken by similar to0.04 Angstrom while c was elongated by similar to0.1 Angstrom, compared with those of their bulk counterparts. Furthermore, there was a substantial amount of disorder in the bond length of the only Zn-O pairs located near the ab plane. This may suggest that the terminating atoms at the boundaries of the nanorods are oxygen atoms. (C) 2005 American Institute of Physics.open114545sciescopu

Social media use and impact during the holiday travel planning process

Through an empirical study among holiday travellers, residing in the Former Soviet Union Republics, this paper presents a comprehensive view of role and impact of social media on the whole holiday travel planning process: Before, during and after the trip, providing insights on usage levels, scope of use, level of influence and trust. Findings suggest that social media are predominantly used after holidays for experience sharing. It is also shown that there is a strong correlation between perceived level of influence from social media and changes made in holiday plans prior to final decisions. Moreover, it is revealed that user-generated content is perceived as more trustworthy when compared to official tourism websites, travel agents and mass media advertising

FIH-1, a novel interactor of mindbomb, functions as an essential anti-angiogenic factor during zebrafish vascular development

Objective: It has been shown that Mindbomb (Mib), an E3 Ubiquitin ligase, is an essential modulator of Notch signaling during development. However, its effects on vascular development remain largely unknown

Impact of visceral fat on skeletal muscle mass and vice versa in a prospective cohort study: The Korean Sarcopenic Obesity Study (KSOS)

Objectives: Sarcopenia and visceral obesity have been suggested to aggravate each other, resulting in a vicious cycle. However, evidence based on prospective study is very limited. Our purpose was to investigate whether visceral fat promotes a decrease in skeletal muscle mass and vice versa. Methods: We observed changes in anthropometric and body composition data during a follow-up period of 27.6±2.8 months in 379 Korean men and women (mean age 51.9±14.6 years) from the Korean Sarcopenic Obesity Study (KSOS). Appendicular lean soft tissue (ALST) mass was calculated using dual-energy X-ray absorptiometry, and visceral fat area (VFA) was measured using computed tomography at baseline and follow-up examination. Results: ALST mass significantly decreased, whereas trunk and total fat mass increased in both men and women despite no significant change in weight and body mass index. In particular, women with visceral obesity at baseline had a greater decrease in ALST mass than those without visceral obesity (P=0.001). In multiple linear regression analysis, baseline VFA was an independent negative predictor of the changes in ALST after adjusting for confounding factors including age, gender, life style and body composition parameters, insulin resistance, high sensitivity C-reactive protein and vitamin D levels (P=0.001), whereas the association between baseline ALST mass and changes in VFA was not statistically significant (P=0.555). Conclusions: This longitudinal study showed that visceral obesity was associated with future loss of skeletal muscle mass in Korean adults. These results may provide novel insight into sarcopenic obesity in an aging society

Chronic low-level expression of HIV-1 Tat promotes a neurodegenerative phenotype with aging

The widespread use of combinational antiretroviral therapies (cART) in developed countries has changed the course of Human Immunodeficiency Virus (HIV) infection from an almost universally fatal disease to a chronic infection for the majority of individuals. Although cART has reduced the severity of neurological damage in HIV-infected individuals, the likelihood of cognitive impairment increases with age, and duration of infection. As cART does not suppress the expression of HIV non-structural proteins, it has been proposed that a constitutive production of HIV regulatory proteins in infected brain cells may contribute to neurological damage. However, this assumption has never been experimentally tested. Here we take advantage of the leaky tetracycline promoter system in the Tat-transgenic mouse to show that a chronic very low-level expression of Tat is associated with astrocyte activation, inflammatory cytokine expression, ceramide accumulation, reductions in brain volume, synaptic, and axonal damage that occurs over a time frame of 1 year. These data suggest that a chronic low-level production of Tat may contribute to progressive neurological damage in virally suppressed HIV-infected individuals

Controlling ferromagnetic easy axis in a layered MoS2 single crystal

We report the effective methods to induce weak ferromagnetism in pristine MoS2 persisting up to room temperature with the improved transport property, which would lead to new spintronics devices. The hydrogenation of MoS2 by heating at 300 degrees C for 1 h leads to the easy axis out of plane, while the irradiation of proton with a dose of 1 x 10(13) P/cm(2) leads to the easy axis in plane. The theoretical modeling supports such magnetic easy axes.open116160Nsciescopu

The Cell Shape-determining Csd6 Protein from Helicobacter pylori Constitutes a New Family of L,D-Carboxypeptidase

Helicobacter pylori causes gastrointestinal diseases, including gastric cancer. Its high motility in the viscous gastric mucosa facilitates colonization of the human stomach and depends on the helical cell shape and the flagella. In H. pylori, Csd6 is one of the cell shape-determining proteins that play key roles in alteration of cross-linking or by trimming of peptidoglycan muropeptides. Csd6 is also involved in deglycosylation of the flagellar protein FlaA. To better understand its function, biochemical, biophysical, and structural characterizations were carried out. We show that Csd6 has a three-domain architecture and exists as a dimer in solution. The N-terminal domain plays a key role in dimerization. The middle catalytic domain resembles those of L,D-transpeptidases, but its pocket-shaped active site is uniquely defined by the four loops I to IV, among which loops I and III show the most distinct variations from the known L,D-transpeptidases. Mass analyses confirm that Csd6 functions only as an L,D-carboxypeptidase and not as an L,D-transpeptidase. The D-Ala-complexed structure suggests possible binding modes of both the substrate and product to the catalytic domain. The C-terminal nuclear transport factor 2-like domain possesses a deep pocket for possible binding of pseudaminic acid, and in silico docking supports its role in deglycosylation of flagellin. On the basis of these findings, it is proposed that H. pylori Csd6 and its homologs constitute a new family of L,D-carboxypeptidase. This work provides insights into the function of Csd6 in regulating the helical cell shape and motility of H. pylori.1165Ysciescopu

Increasing uptake of colorectal cancer screening in Korea: a population-based study

<p>Abstract</p> <p>Background</p> <p>Colorectal cancer (CRC) screening rates are low in most Asian countries and remain largely unknown. This study examined trends in CRC screening rates after the introduction of the Korean National Cancer Screening Programme (NCSP) and determined the factors associated with uptake of CRC screening by test modality over time.</p> <p>Methods</p> <p>An annual population-based survey conducted through nationally representative random sampling from 2005-2008. In total, 3,699 participants from the 2005-2008 surveys were selected as study subjects. Face-to-face interviews were performed to assess the utilization rate of CRC screening by each screening modality.</p> <p>Results</p> <p>Overall, CRC screening within the recommended time interval increased significantly from 22.9% in 2005 to 36.6% in 2008 (<it>p </it>< 0.001). The proportion of subjects receiving a fecal occult blood test (FOBT) test within the previous year increased significantly from 7.2% in 2005 to 21.3% in 2008 (<it>p </it>< 0.001). Increases in FOBT testing were highest among those who had a lower income status (relative difference = 511.9%) and women (relative difference = 266.1%). Endoscopy use also increased from 18.0% in 2005 to 20.5% in 2008, albeit not significant. Overall, those who were male, non-smokers, 60-69 years old, and had a higher income status were more likely to have undergone up-to-date endoscopy and CRC screening.</p> <p>Conclusions</p> <p>This study revealed a substantial increase in up-to-date CRC screening in the general population from 2005 to 2008. However, more than half of adults in Korea are still not up-to-date with their CRC tests. It will be important to continue to investigate factors associated with up-to-date CRC screening by each modality.</p

Pathophysiology and pathogenesis of circadian rhythm sleep disorders

Metabolic, physiological and behavioral processes exhibit 24-hour rhythms in most organisms, including humans. These rhythms are driven by a system of self-sustained clocks and are entrained by environmental cues such as light-dark cycles as well as food intake. In mammals, the circadian clock system is hierarchically organized such that the master clock in the suprachiasmatic nuclei of the hypothalamus integrates environmental information and synchronizes the phase of oscillators in peripheral tissues. The transcription and translation feedback loops of multiple clock genes are involved in the molecular mechanism of the circadian system. Disturbed circadian rhythms are known to be closely related to many diseases, including sleep disorders. Advanced sleep phase type, delayed sleep phase type and nonentrained type of circadian rhythm sleep disorders (CRSDs) are thought to result from disorganization of the circadian system. Evaluation of circadian phenotypes is indispensable to understanding the pathophysiology of CRSD. It is laborious and costly to assess an individual's circadian properties precisely, however, because the subject is usually required to stay in a laboratory environment free from external cues and masking effects for a minimum of several weeks. More convenient measurements of circadian rhythms are therefore needed to reduce patients' burden. In this review, we discuss the pathophysiology and pathogenesis of CRSD as well as surrogate measurements for assessing an individual's circadian phenotype