Y. B. Xu

Model calculation for the field enhancement factor of carbon nanotube

To estimate the apex field enhancement factor associated with carbon nanotube on a planar cathode surface, the simple model of floated sphere between parallel anode and cathode plates was studied. When the anode-cathode distance d is much larger than the height h of carbon nanotube, the field enhancement factor of carbon nanotube was given as the following expression β0=h∕ρ+3.5 with the image method, which is a little than the early work of Miller. Finally, the influence of the anode-cathode distance on the enhancement factor was also discussed and the expression of enhancement factor of carbon nanotube should be modified to be β=h∕ρ+3.5+A(h∕d)3, where A is the constant. This shows a much weaker influence of the relatively smaller anode-cathode distance on the field enhancement factor of carbon nanotube than that estimated earlier. Thus, we can lower the threshold voltage to some extent by the decrease of the anode-cathode distance. The higher aspect ratio of carbon nanotube and the lower anode-cathode di...

Increased risk of cancer in patients with type 2 diabetes mellitus: A retrospective cohort study in China

BackgroundPrevious studies indicated that type 2 diabetes mellitus (T2DM) might be associated with the risk of cancer. The aim of this study was to investigate the association between T2DM and the risk of developing common cancers in a Chinese population.MethodsA population-based retrospective cohort study was carried out in the Nan-Hu district of Jiaxing city, Zhejiang province, China. The incidence of cancer cases among type 2 diabetic patients were identified through record-linkage of the Diabetic Surveillance and Registry Database with the Cancer Database from January 2002 to June 2008. The standardized incidence ratio (SIR) and 95% confidence interval (CI) were estimated for the risk of cancer among the patients with type 2 diabetes.ResultsThe overall incidence of cancer was 1083.6 per 105 subjects in male T2DM patients and 870.2 per 105 in females. Increased risk of developing cancer was found in both male and female T2DM patients with an SIR of 1.331 (95% CI = 1.143-1.518) and 1.737 (1.478-1.997), respectively. As for cancer subtypes, both male and female T2DM patients had a significantly increased risk of pancreatic cancer with the SIRs of 2.973 (1.73-4.21) and 2.687 (1.445-3.928), respectively. Elevated risk of liver and kidney cancers was only found in male T2DM patients with SIRs of 1.538 (1.005-2.072) and 4.091 (1.418-6.764), respectively. Increased risks of developing breast cancer [2.209 (1.487-2.93)] and leukemia SIR: [4.167 (1.584- 6.749) ] were found in female patients.ConclusionsThese findings indicated that patients with T2DM have an increased risk of developing cancer. Additional cancer screening should be employed in the management of patients with T2DM.

Field-enhancement factor for carbon nanotube array

To estimate the apex field-enhancement factor associated with an array of carbon nanotubes (CNTs) on a planar cathode surface, the model of the floating spheres between parallel anode and cathode plates was proposed. An approximate formula for the enhancement factor was derived showing that the intertube distance of a CNT array critically affects the field emission. When the intertube distance is less than the height of the tube, the enhancement factor decreases rapidly with decreasing distance in qualitative agreement with the numerical simulation. Considering the field-emission current density, the field emission can be optimized when the intertube distance is comparable with the tube height, in accordance with the results from the experiments. Finally, the influence of the anode-cathode distance on the enhancement factor was also discussed, showing that the anode-cathode distance has little effect on the field emission from a CNT array. Thus, we can reduce the theshold voltage to some extent by decreas...

Susceptibility loci for metabolic syndrome and metabolic components identified in Han Chinese: a multi‐stage genome‐wide association study

Metabolic syndrome (MetS), a cluster of metabolic disturbances that increase the risk for cardiovascular disease and diabetes, was because of genetic susceptibility and environmental risk factors. To identify the genetic variants associated with MetS and metabolic components, we conducted a genome‐wide association study followed by replications in totally 12,720 participants from the north, north‐eastern and eastern China. In combined analyses, independent of the top known signal at rs651821 on APOA5, we newly identified a secondary triglyceride‐associated signal at rs180326 on BUD13 (Pcombined = 2.4 × 10−8). Notably, by an integrated analysis of the genotypes and the serum levels of APOA5, BUD13 and triglyceride, we observed that BUD13 was another potential mediator, besides APOA5, of the association between rs651821 and serum triglyceride. rs671 (ALDH2), an east Asian‐specific common variant, was found to be associated with MetS (Pcombined = 9.7 × 10−22) in Han Chinese. The effects of rs671 on metabolic components were more prominent in drinkers than in non‐drinkers. The replicated loci provided information on the genetic basis and mechanisms of MetS and metabolic components in Han Chinese.

Synthesis and characterization of inorganic solid electrolytes of Li2O-SiO2-P2O5 and Li2O-TiO2-SiO2-P2O5 systems

The lithium-ion-conducting inorganic solid electrolytes in the oxide systems Li2O-SiO2-P2O5 and Li2O-TiO2-SiO2-P2O5 were prepared by the solid-state reaction, and the electrolyte pellet made by cold-pressing method had diameter of 13 mm and was about 1 mm thick. Phase identification and surface morphology of the products were carried out by X-ray diffraction and scanning electron microscopy. Ionic conductivity of the pellets was investigated through ac impedance. The results show that the adding of other cations can improve the ionic conductivity of the solid electrolyte, and the sintering temperature and duration can influence the ionic conductivity. The maximum ionic conductivity in the samples is 9.9 × 10−4 S/cm in the Li2O-TiO2-SiO2-P2O5 system.

The influence of ethanol on the growth and structure of carbon nanotubes

Using chemical vapor deposition to decompose ethanol at high temperature with Fe2+/zeolite as catalyst, we synthesized carbon nanotubes (CNTs) with thinner walls and open ends. Compared with CNTs synthesized from methane (CH4), the CNTs synthesized here are straighter and have larger inner diameters and fewer defects when the experimental parameters are well controlled. CNTs of such structures will have greater potential applications.

The polymorphism rs671 at ALDH2 associated with serum uric acid levels in Chinese Han males: A genome-wide association study

Serum uric acid (SUA) levels are highly heritable and an increased SUA level is one of important risk factors for gout, diabetes, metabolic syndrome, and cardiovascular diseases. The genetic variants underlying SUA remains largely unexplored. The aim was to explore new genetic variants underlying SUA in Chinese Han. We performed a genome-wide association study of SUA levels in Han Chinese. The discovery set contained 1634 samples and subsequent replication was comprised of 1649 females and 1169 males. 2620 subjects were recruited in the detailed analysis of rs671, alcohol drinking and SUA. We found a genome-wide significant association between SUA level and the SNP rs671 at ALDH2 (P = 1.2 × 10-10) in the merged data. In addition, we also replicated the signal from rs3733590 at SLC2A9 (P = 1.0 × 10-10). In males, about 0.21% to 1.95% of the total variance for SUA can be explained by rs671 using linear regression models in four independent cohorts. Of those, 56.75% to 93.51% might be explained by altering alcohol consumption due to rs671. No statistical association of rs671 and SUA was observed in females (P = 0.409). Furthermore, we observed a causal relationship between alcohol consumption and SUA in males using rs671 as an instrumental variable (P = 5.1 × 10-4). We replicated the previous findings in SLC2A9. Our evidence supported that rs671 was associated with SUA by affecting alcohol consumption in males. This finding strongly suggests a role for alcohol consumption in the development of hyperuricaemia and uric acid related traits.

The orbital symmetry of carbon monoxide on a Cs-precovered Ru(1010) surface

The molecular orbitals of CO are rearranged under the strong influence of coadsorbed Cs atoms. The peak for CO on the clean surface, at 7.5 eV BE attributed to the and orbits, is split into two peaks; one is at 6.3 eV BE and the other 7.8 eV BE. The peak at 6.3 eV BE shows an anti-symmetry character about the plane parallel to the crystallographic direction in the surface.

High-resolution electron energy loss spectroscopy and angle-resolved ultra-violet photoemission spectroscopy studies of carbon monoxide on a Cs-precovered surface

There are two molecular adsorption states of CO in the system. One is , with lower C - O frequency, and the other is , with higher C - O frequency. The latter is similar to that on a clean surface. The two states of CO are occupied sequentially during the exposure to CO. The C - O stretch frequency of both states shifts to a higher value with the exposure to CO and to a lower value with higher Cs precoverage. The electronic structure of the molecule is different from that of the molecule and is of the same character as CO in a tilted mode.