脂肪组织DNA甲基化与糖尿病和肥胖的发生发展

糖尿病和肥胖是经常一起出现的复杂性代谢疾病,均受遗传因素和环境因素双重影响。越来越多的研究表明,DNA甲基化的变化会导致糖尿病和肥胖的发生。脂肪组织是糖尿病和肥胖主要的受累组织,同时作为内分泌器官参与多种病理生理过程,调节机体代谢平衡。脂肪组织相关基因的DNA甲基化变化会影响脂肪组织功能,从而与糖尿病和肥胖的发生密切相关。本文主要阐述糖尿病患者和肥胖患者不同类型脂肪组织DNA甲基化变化,以期深入了解糖尿病和肥胖发生发展的可能机制和探寻可能的防治途径。

Superior performance of iridium supported on rutile titania for the catalytic decomposition of N_2O propellants

N2O is a promising green propellant and exhibits great potential for satellite propulsion systems. It is difficult for catalytic decomposition, which is an important way to initiate the propulsion process, to occur at temperatures below 600 °C due to the high activation energy of N2O. In this work, we report an Ir supported on rutile TiO2（Ir/r-TiO2） catalyst which exhibits a fairly high activity for high-concentration N2O decomposition. HAADF-STEM, H2-TPR, and XPS results indicate that highly dispersed Ir particles and improved oxygen mobility on the Ir/r-TiO2 could facilitate the decompo-sition of N2O and desorption of the adsorbed oxygen. Bridge-bonded peroxide intermediates were observed with in-situ DRIFT and herein, a detailed decomposition route is proposed.

A palladium single-atom catalyst toward efficient activation of molecular oxygen for cinnamyl alcohol oxidation

Selective aerobic oxidation of alcohols under mild conditions is of great importance yet challenging,with the activation of molecular oxygen(O2)as a crucial capability of the catalysts.Herein,we demonstrate that an Al2O3-supported Pd single-atom catalyst leads to higher activity and selectivity compared to Pd nanoparticles for the oxidation of cinnamyl alcohol.The Al2O3 support used in this study is rich in coordinately unsaturated Al3+sites,which are apt for binding to Pd atoms through oxygen bridges and present a distinct metal-support interaction(MSI).The suitable MSI then leads to a unique electronic characteristic of the Pd single atoms,which can be confirmed via X-ray photoelectron spectroscopy,normalized X-ray absorption near-edge structure,and diffuse reflectance Fourier transform infrared spectroscopy.Moreover,this unique electronic state is proposed to be responsible for its high catalytic activity.With the help of in-situ UV-vis spectra and electron spin resonance spectra,a specific alcohol oxidation route with O2 activation mechanism is then identified.Active oxygen species behaving chemically like singlet-O2 are generated from the interaction of O2 with Pd1/Al2O3,and then oxidize the partially dehydrogenated intermediates produced by the adsorbed allylic alcohols and Pd atoms to the desired alkenyl aldehyde.This work provides a promising path for the design and development of high-activity catalysts for aerobic oxidation reactions.

Delayed detached eddy simulations of fighter aircraft at high angle of attack

The massively separated flows over a realistic aircraft configuration at 40？, 50？, and 60？angles of attack are studied using the delayed detached eddy simulation（DDES）.The calculations are carried out at experimental conditions corresponding to a mean aerodynamic chord-based Reynolds number of 8.93 × 10~5 and Mach number of 0.088. The influence of the grid size is investigated using two grids, 20.0×10~6cells and 31.0 × 10~6 cells. At the selected conditions, the lift,drag, and pitching moment from DDES predictions agree with the experimental data better than that from the Reynoldsaveraged Navier–Stokes. The effect of angle of attack on the flow structure over the general aircraft is also studied, and it is found that the dominated frequency associated with the vortex shedding process decreases with increasing angle of attack.

经脐单孔腹腔镜治疗肾囊肿16例临床分析

目的探讨完全经脐单孔腹腔镜肾囊肿去顶术的临床疗效。方法2013年6月~2015年6月我院采用经脐单孔腹腔镜对16例单纯性肾囊肿患者行肾囊肿去顶术。结果16例手术均获成功,手术时间45~110min,平均时间66.25 min,术中出血5~40ml,平均15ml。均无中转开放手术及输血,术后随访6个月,均无并发症发生,术后疤痕不明显。结论经脐单孔腹腔镜下肾囊肿去顶术具有出血少、恢复快、美容效果好、术后并发症少等优点,是一种安全可行手术方式。

First principles study on geometric and electronic properties of two-dimensional Nb_(2)CT_(x) MXenes

MXenes are a new type of two-dimensional carbides with rich physical and chemical properties. The physics of MXenes, and thus the applications, are dominated by surface functional groups. Herein, the effects of different terminations(O,S, Se, Te) on the geometric and electronic properties of Nb_(2)C MXenes were studied via density functional theory(DFT)calculations. Three adsorption sites were examined to determine the most stable configurations. The results showed that both the types and the positions of surface functional groups influence the geometric stability and physical characters of Nb_(2)C. The S and Se terminations make the Nb_(2)C MXenes to be semiconductor, while Nb_(2)C MXenes with other terminations(O, Te) are conductor. The electron location function, density of states, Bader charge distribution, and the projected crystal orbital Hamilton population were conducted to explain the origin of adsorption stability and electronic nature difference. Our results provide a fundamental understanding about the effects of surface terminations on the intrinsic stability and electronic properties of Nb_(2)C MXenes.

CBX4 deletion promotes tumorigenesis under Kras^(G12D) background by inducing genomic instability

Chromobox protein homolog 4(CBX4)is a component of the Polycomb group(PcG)multiprotein Polycomb repressive complexes 1(PRC1),which is participated in several processes including growth,senescence,immunity,and tissue repair.CBX4 has been shown to have diverse,even opposite functions in different types of tissue and malignancy in previous studies.

Bird community comparisons of four plantations and conservation concerns in South China

Plantations of non-native,fast-growing trees are increasing in the tropics and subtropics,perhaps with negative consequences for the native avifauna.We studied bird diversity in 4 types of plantations in South China to deter-mine which plantation types are especially detrimental,and compared our findings with studies in nearby natu-ral forests to assess the magnitude of the negative impact.A total of 57 species was recorded.The mean capture rate of understory birds was 1.7 individuals 100-net-h-1.Bird richness and capture rate were lower in plantations than in nearby natural forests.Babblers(Timaliidae),primarily forest-dependent species in South China,were particularly under-represented in plantations.Species richness,composition and bird density,particularly of un-derstory birds,differed between plantation types.Plantations of Schima,which is native to South China,had the highest species richness according to point count data.Plantations of Acacia(non-native)supported the highest understory species richness and produced the highest capture rate of understory birds,probably because of their complex structure and high arthropod abundance.If bird diversity is to be considered,we strongly recommend that future re-afforestation projects in South China should,as far as possible,use mixed native tree species,and especially Schima,ahead of the other species.

Wall pressure beneath a transitional hypersonic boundary layer over an inclined straight circular cone

Properties of wall pressure beneath a transitional hypersonic boundary layer over a 7°half-angle blunt cone at angle of attack 6°are studied by Direct Numerical Simulation.The wall pressure has two distinct frequency peaks.The low-frequency peak with f≈10−50 kHz is very likely the unsteady crossflow mode based on its convection direction,i.e.along the axial direction and towards the windward symmetry ray.Highfrequency peaks are roughly proportional to the local boundary layer thickness.Along the trajectories of stationary crossflow vortices,the location of intense high-frequency wall pressure moves from the bottom of trough where the boundary layer is thin to the bottom of shoulder where the boundary layer is thick.By comparing the pressure field with that inside a high-speed transitional swept-wing boundary layer dominated by the z-type secondary crossflow mode,we found that the high-frequency signal originates from the Mack mode and evolves into the secondary crossflow instability.

A Four-Equation Eddy-Viscosity Approach for Modeling Bypass Transition

It is very important to predict the bypass transition in the simulation of flows through turbomachinery.This paper presents a four-equation eddy-viscosity turbulence transition model for prediction of bypass transition.It is based on the SST turbulence model and the laminar kinetic energy concept.A transport equation for the non-turbulent viscosity is proposed to predict the development of the laminar kinetic energy in the pre-transitional boundary layer flow which has been observed in experiments.The turbulence breakdown process is then captured with an intermittency transport equation in the transitional region.The performance of this new transition model is validated through the experimental cases of T3AM,T3A and T3B.Results in this paper show that the new transition model can reach good agreement in predicting bypass transition,and is compatible with modern CFD software by using local variables.

Binary-ternary transition metal chalcogenides interlayer coupling in van der Waals type-II heterostructure for visible-infrared photodetector with efficient suppression dark currents

Ternary two-dimentional(2D)materials exhibit diverse physical properties depending on their composition,structure,and thickness.Through forming heterostructures with other binary materials that show similar structure,there can be numerous potential applications of these ternary 2D materials.In this work,we reported the structure of few-layer CrPS_(4)by X-ray diffraction,transmission electron microscope,and electron-density distribution calculation.We also demonstrated a new application of the CrPS_(4)/MoS_(2)heterobilayer:visible-infrared photodetectors with type-II staggered band alignment at room temperature.The response of the heterostructure to infrared light results from a strong interlayer coupling that reduces the energy interval in the junction area.Since the intrinsic bandgap of individual components determines wavelengths,the decrease in energy interval allows better detection of light that has a longer wavelength.We used photoluminescence(PL)spectroscopy,Kelvin probe force microscopy(KPFM)under illumination,and electrical transport measurements to verify the photoinduced charge separation between the CrPS_(4)/MoS_(2)heterostructures.At forward bias,the device functioned as a highly sensitive photodetector,as the wavelength-dependent photocurrent measurement achieved the observation of optical excitation from 532 to 1,450 nm wavelength.Moreover,the photocurrent caused by interlayer exciton reached around 1.2 nA at 1,095 nm wavelength.Our demonstration of the strong interlayer coupling in the CrPS_(4)/MoS_(2)heterostructure may further the understanding of the essential physics behind binary-ternary transition metal chalcogenides heterostructure and pave a way for their potential applications in visible-infrared devices.

INVERSION OF ELECTRON TOMOGRAPHY IMAGES USING L^2-GRADIENT FLOWS -- COMPUTATIONAL METHODS

In this paper, we present a stable, reliable and robust method for reconstructing a three dimensional density function from a set of two dimensional electric tomographic images. By minimizing an energy functional consisting of a fidelity term and a regularization term, an L^2-gradient flow is derived. The flow is integrated by a finite element method in the spatial direction and an explicit Euler scheme in temporal direction. The experimental results show that the proposed method is efficient and effective.

CONSTRUCTION OF GEOMETRIC PARTIAL DIFFERENTIAL EQUATIONS FOR LEVEL SETS

Geometric partial differential equations of level-set form are usually constructed by a variational method using either Dirac delta function or co-area formula in the energy functional to be minimized. However, the equations derived by these two approaches are not consistent. In this paper, we present a third approach for constructing the level-set form equations. By representing various differential geometry quantities and differential geometry operators in terms of the implicit surface, we are able to reformulate three classes of parametric geometric partial differential equations （second-order, fourth-order and sixth- order） into the level-set forms. The reformulation of the equations is generic and simple, and the resulting equations are consistent with their parametric form counterparts. We further prove that the equations derived using co-area formula are also consistent with the parametric forms. However, these equations are of much complicated forms than these given by the equations we derived.

Effects of acid deposition on the avoidance behavior of Folsomia candida (Collembola, Isotomidae)

Excessive acid deposition causes soil acidification,and changes the soil microhabitat,thus affecting the survival and reproduction of soil organisms.Folsomia candida(Collembola,Isotomidae),as a model organism,is widely used to assess the chemical toxicity in soil,and its avoidance response can indicate the environmental changes.In this study,we used Folsomia candida to assess the risks of acid deposition on soil ecosystems.Different pH(3.0,3.5,4.0,4.5,5.0,and 5.5)treatments were set up in petri dish experiments,and the avoidance behavior of Folsomia candida was measured after 12,24,and 48 h exposure to the pH conditions.The results indicated that(1)both the exposure duration and pH level influenced avoidance behavior of collembolan.(2)After 12 h exposure,most of the individuals showed avoidance behavior but without significant differences among the treatments.(3)After 24 h exposure,significant avoidance behavior was observed at pH 3.0,3.5,and 4.0.(4)After 48 h exposure,avoidance behavior was found in all treatment conditions except for pH 5.5.This study clarified the direct responses of soil fauna to acid deposition,and indicated that both pH and length of exposure influenced the avoidance behavior of Folsomia candida.During the experimental period,the collembolan reacted negatively and showed consistent avoidance behavior at pH 3.0,3.5,and 4.0.Reversed avoidance behavior was apparent between pH 4.5 and 5.0 and not observed at pH 5.5,indicating that the latter was the preferred pH environment.