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The COllaborative project of Development of Anthropometrical measures in Twins (CODATwins) project is a large international collaborative effort to analyze individual-level phenotype data from twins in multiple cohorts from different environments. The main objective is to study factors that modify genetic and environmental variation of height, body mass index (BMI, kg/m2) and size at birth, and additionally to address other research questions such as long-term consequences of birth size. The project started in 2013 and is open to all twin projects in the world having height and weight measures on twins with information on zygosity. Thus far, 54 twin projects from 24 countries have provided individual-level data. The CODATwins database includes 489,981 twin individuals (228,635 complete twin pairs). Since many twin cohorts have collected longitudinal data, there is a total of 1,049,785 height and weight observations. For many cohorts, we also have information on birth weight and length, own smoking behavior and own or parental education. We found that the heritability estimates of height and BMI systematically changed from infancy to old age. Remarkably, only minor differences in the heritability estimates were found across cultural–geographic regions, measurement time and birth cohort for height and BMI. In addition to genetic epidemiological studies, we looked at associations of height and BMI with education, birth weight and smoking status. Within-family analyses examined differences within same-sex and opposite-sex dizygotic twins in birth size and later development. The CODATwins project demonstrates the feasibility and value of international collaboration to address gene-by-exposure interactions that require large sample sizes and address the effects of different exposures across time, geographical regions and socioeconomic status.
Vessel flexure can be triggered naturally by surgical operation, heart pulsation and body movement. It may affect the mechanical behavior of the stent and the existence of a stent may in turn cause vessel injury. In the present study, the finite element method is employed to study the interaction between stent and vessel during vessel flexure. Two- and four-link stents made of stainless steel 316L and magnesium alloy WE43 are considered. Results indicate that longitudinal deformation of the stent can be caused by vessel flexure, and the higher levels of stress exist in the link struts. The existence of the stent could induce significant stress concentration and straightened deformation on vessel wall in the course of vessel flexure. Stents with more links or made of harder materials show greater anti-deformation capability, thus inducing a more severe stress concentration and straightened deformation on the vessel wall. The bending direction also affects the mechanical performance of the vessel-stent system. The results obtained could provide useful information for better stent designs and clinical decisions.
Phenoloxidase (PO) plays a key role in melanin biosynthesis during insect development. Here, we isolated the 2310-bp full-length cDNA of PPO1 from Zeugodacus tau, a destructive horticultural pest. qRT-polymerase chain reaction showed that the ZtPPO1 transcripts were highly expressed during larval–prepupal transition and in the haemolymph. When the larvae were fed a 1.66% kojic acid (KA)-containing diet, the levels of the ZtPPO1 transcripts significantly increased by 2.79- and 3.39-fold in the whole larvae and cuticles, respectively, while the corresponding PO activity was significantly reduced; in addition, the larval and pupal durations were significantly prolonged; pupal weights were lowered; and abnormal phenotypes were observed. An in vitro inhibition experiment indicated that KA was an effective competitive inhibitor of PO in Z. tau. Additionally, the functional analysis showed that 20E could significantly up-regulate the expression of ZtPPO1, induce lower pupal weight, and advance pupation. Knockdown of the ZtPPO1 gene by RNAi significantly decreased mRNA levels after 24 h and led to low pupation rates and incomplete pupae with abnormal phenotypes during the larval-pupal interim period. These results proved that PO is important for the normal growth of Z. tau and that KA can disrupt the development of this pest insect.
We present an overview of the performance of the Neutralized Drift Compression Experiment-II (NDCX-II) accelerator at Berkeley Lab, and report on recent target experiments on beam-driven melting and transmission ion energy loss measurements with nanosecond and millimeter-scale ion beam pulses and thin tin foils. Bunches with around 1011 ions, 1 mm radius, and 2–30 ns full width at half maximum duration have been created with corresponding fluences in the range of 0.1–0.7 J/cm2. To achieve these short pulse durations and mm-scale focal spot radii, the 1.1 MeV [megaelectronvolt (106 eV)] He+ ion beam is neutralized in a drift compression section, which removes the space charge defocusing effect during final compression and focusing. The beam space charge and drift compression techniques resemble necessary beam conditions and manipulations in heavy ion inertial fusion accelerators. Quantitative comparison of detailed particle-in-cell simulations with the experiment plays an important role in optimizing accelerator performance.
The strain gradient elasticity theory including only three independent material length scale parameters has been proposed by Zhou et al. to explain the size effect phenomena in micro scales. In this paper, the general formulations of strain gradient elasticity theory in orthogonal curvilinear coordinates are derived, and then are specified for the cylindrical and spherical coordinates for the convenience of applications in cases where orthogonal curvilinear coordinates are suitable. Two basic problems, one is the twist of a cylindrical bar and the other is the radial deformation of a solid sphere, are analyzed under the cylindrical and spherical coordinates, respectively. The results reveal that only the material length scale parameter l2 enters the torsion problem, while completely disappears in the problem of radial deformation of a sphere. The size effect of radial deformation of a solid sphere is controlled by the material length scale parameters l1 and l2. In addition, for the incompressible solid sphere especially, only the material length scale parameter l1 enters this radial deformation problem by neglecting the strain gradient terms associated with hydrostatic strains. Predictably, the present paper offers an alternative avenue for measuring the three independent material length scale parameters from bar twisting and sphere expansion tests.
Flexoelectricity, the coupling of strain gradient to polarization, enhances the properties of piezoelectric response desirable for advanced MEMS dramatically even in centrosymmetric dielectrics. In this paper, the general formulations of the flexoelectric couple stress theory presented by Hadjesfandiari in orthogonal curvilinear coordinate system are derived, and are then specified for the case of cylindrical coordinates. A size-dependent flexoelectric model of circular plate is established based on the current formulations in cylindrical coordinates. The governing equations, boundary conditions and initial conditions are derived by applying Hamilton's principle. The static bending and free vibration problems of a simply supported axisymmetric circular plate are carried out to illustrate the applicability of the present model. Numerical results reveal that a homogeneous electric field between the up and down surfaces of the circular plate is induced indeed. The generated deflection, induced voltage and natural frequency show obvious size effect, but the size effect is almost diminishing as the thickness of the plate is far greater than the material length scale parameter. As the increase of the flexoelectric coefficient, the induced voltage increases evidently and the generated deflection and the natural frequency increase weakly.
A scheme for the improvement of proton beam quality by the optimized dragging field from the interaction of ultraintense laser pulse with a complex double-layer target is proposed and demonstrated by one-dimensional particle-in-cell (Opic1D) simulations. The complex double-layer target consists of an overdense proton thin foil followed by a mixed hydrocarbon (CH) underdense plasma. Because of the existence of carbon ions, the dragging field in the mixed CH underdense plasma becomes stronger and flatter in the location of the proton beam than that in a pure hydrogen (H) underdense plasma. The optimized dragging field can keep trapping and accelerating protons in the mixed CH underdense target to high quality. Consequently, the energy spread of the proton beam in the mixed CH underdense plasma can be greatly reduced down to 2.6% and average energy of protons can reach to 9 GeV with circularly polarized lasers at intensities 2.74 × 1022 W/cm2.
We report our preliminary results on the role of starbursts in LINERS by use of Wolf-Rayet galaxies as a tool. The essence of this approach lies in the different FIR-radio relation of WR galaxies from the pure AGN's.
We report the discovery of two new Wolf-Rayet galaxies: Mrk 1039, and F8208+2816. Two broad WR bumps at 5808Å and 4650Å indicate the presence of WCE and WNL star populations in these two sources. Comparison of the observed EW(HeII λ4686) and EW(CIV λ5808) with recent models of WR populations in young starbursts provide an indication that the stellar initial mass function in some WR galaxies might not be Salpeter-like.
On 23 September 1998 there was a 3B/M7.1 flare event starting at 06:40 UT with more than 100 minute duration radio bursts of 1134 sfu peak flux at 2840 MHz and accompanying a CME. In this paper, the event is analyzed with the data observed by Beijing Astronomical Observatory (BAO), OSRA-Tremsdorf (AIP) and SSRT-ISTP. In particular, we compare the fine structures (FS) during the triggering phase revealed in different regimes and discuss their implications.
Human infection with the emerging avian influenza A(H7N9) virus in China in 2013 has raised global concerns. We conducted a retrospective descriptive study of 27 confirmed human influenza A(H7N9) cases in Jiangsu Province, to elaborate poultry-related exposures and to provide a more precise estimate of the incubation periods of the illness. The median incubation period was 6 days (range 2–10 days) in cases with single known exposure and was 7·5 days (range 6·5–12·5 days) in cases with exposures on multiple days, difference between the two groups was not significant (Z = −1·895, P = 0·058). The overall median incubation period for all patients was estimated to be 7·5 days (range 2–12·5 days). Our findings further highlight the necessity for public health authorities to extend the period of medical surveillance from 7 days to 10 days.
In this work, we investigated the influence of N-polar wet etching on the properties of nitride-based hexagonal pyramids array (HPA) vertical-injection light emitting diodes (V-LEDs). The cathodeluminescence images showed the randomly distribution of hexagonal pyramids with isolated active regions. The transmission electron microscopy images demonstrated the reduced density of threading dislocations. The IQE was estimated by temperature dependence of photoluminescence, which showed 30% increase for HPA V-LEDs compared with broad area (BA) V-LEDs. The improved extraction efficiency was verified by finite difference time domain simulation, which was 20% higher than that of roughened BA V-LEDs. The electrical properties of HPA V-LEDs were measured by conductive atomic force microscopy (CAFM) measurements. HPA V-LEDs exhibited much lower leakage current due to the improved crystal quality.
Vanadium oxides thin films with variable oxidation states have attracted great attention due to their unique electrical, optical properties and many important applications in microelectronics, infrared optical devices, and energy harvest systems. However, to fabricate vanadium oxide thin films with controllable phases and desired transport properties is still a challenge by using a chemical solution deposition (CSD) technique. In this paper, we report that vanadium oxide thin films with well controlled phases such as rhombohedral V2O3 and monoclinic VO2 could be synthesized on Al2O3 (0001) substrates using a CSD technique ---- polymer assisted deposition (PAD). Both V2O3 and VO2 thin films can be well controlled with good epitaxial quality by optimizing the fabrication parameters. The electrical resistivity changes 3∼4 orders of magnitude at metal insulator transition for both epitaxial V2O3 and VO2 thin films. The correlation between the physical properties and the microstructures of the films will be discussed.
In the past two decades, the growing global demand for solar energy has spurred scientific interest in alternative technologies to conventional silicon. In particular, CuIn1-xGaxSe2 (CIGS) has emerged as a competitor. We have developed a scalable deposition technique using RF magnetron sputtering of quaternary CIGS. Notably, the resulting films do not require postselenization, reducing processing time and cost. We have fabricated devices above 10% efficiency using this approach, showing its promise as a production method for highperformance CIGS photovoltaics. However, the morphology of the sputtered CIGS layer is markedly different from conventional evaporated films; grain sizes vary through the thickness of the film, with numerous small grains dominating at the Mo/CIGS interface that then either terminate or grow in an inverted-pyramid fashion to form large, columnar grains at the CIGS/CdS interface.
To better understand the origin of this morphology, we have studied the growth behavior of the CIGS layer using a combination of atomic force microscopy and electron microscopy to observe initial nucleation and grain growth behavior of quaternary-sputtered CIGS. We also discuss the effects of interfacial layers at the Mo/CIGS interface, demonstrating a novel wetting layer that conformally coats the Mo surface.
We report fabrication of random nanometer-scale radial p-n junction solar cells (SCs). Nanoholes were fabricated on the Si wafer by combining silver film annealing and metal catalyzed electrochemical etching (MECC) of the material. The dimension of the holes can be adjusted by varying the annealing conditions and the thickness of the Ag film. Systematic investigations on the effects of the nanohole size and the doping conditions on the cell efficiency were performed.
Phase transformations by yttrium implantation into pure aluminum using 60kV ions and 3×1017 ions/cm2 dose have been studied by transmission electron microscopy (TEM). YAl3(12R) particles with an average size of 0.3μm were formed in the modified aluminum surface, which transformed into YFe3·5Alx (predominantly) and YAl3(8H) phase particles with 2 μm average diameter after being annealed at 600°C for one hour. The Fe ions were introduced by ion sputtering from the iron screws of the specimen holder, a previously unnoticed effect during heavy metal ion implantation for surface modification of materials. Electron diffraction experiments indicated that the YFe3·5Alx was a new phase and belongs to the orthorhombic system with a C-face-centered lattice (a=c=0.887nm, b=1.024nm). The reciprocal lattice of the YFe3·5Alx phase is related to that of the YFe4Al8 magnetic phase. The microstructure of the modified aluminum surface was also investigated by high-resolution TEM.
Aluminum nitride (AlN), a wide band gap semiconductor (Eg = 6.2eV), has potential applications in microelectronics due to its excellent insulating properties and compatibility with silicon [1,2]. More recently, the use of AlN thin films in high electron mobility transistors, light emitting diodes and UV sources is explored by altering the band gap of the material . The present work describes the combinatorial synthesis of (Al,Ti)N thin films via pulsed laser deposition (PLD) technique to obtain desirable compositional spreads and corresponding variations in the electrical properties. Films of AlN, TiN and (Al,Ti)N were deposited on 6H-SiC (0001) substrates held at a temperature of 680°C. The surface quality of the films examined using an AFM revealed island growth of SiO2 and other growth patterns possibly related to substrate defects.
X-ray diffraction studies indicated that the growth of AlN and TiN films occurred with corresponding habit planes of (0002) and (111) parallel to the substrate surface. Compositional investigations conducted using energy dispersive spectroscopy (EDS) and x-ray photoelectron spectroscopy (XPS) showed systematic changes in the Al and Ti composition across the thickness of the compositional spread film. Cross-sectional analysis of (Al,Ti)N films conducted in a high-resolution transmission electron microscope revealed that the films were multi-layered. Several orders of magnitude decrease in the measured resistivity across a 15 mm length (Al,Ti)N film was noted corresponding to a systematic increase in the Ti content. Further optimization of deposition conditions is essential for producing thicker films.
Mixed metal clusters (n-Bu4N)3[WCu3Br4S4] (I), (n-Bu4N)3[Wag3Br4S4] (II), (n-Bu4N)3[MoAg3BrCl3S4] (III) and (n-Bu4N)3[MoAg3BrI3S4] (IV) were synthesized by solid state reactions. The cluster anions assume cubic cage shaped structures and possess strong optical limiting capability. At very low fluences the molecules respond linearly to the incident light obeying Beer's law. As light fluence rises their molecular absorptivities increase rapidly exhibiting limiting effect with threshold and saturation fluence of 1.3 J/cm2 and 0.7 J/cm2 for compound I, 0.7 J/cm2 and 0.5 J/cm2 for compound II, 0.6 J/cm2 and 0.3 J/cm2 for compound III, and 0.5 J/cm2 and 0.3 J/cm2 for compound IV respectively. The threshold and saturation values of compound IV are about 3 and 2 times better than those of C60 measured under identical conditions. The optical limiting capability of the clusters is derived from excited state absorption, a process that turns on within nanoseconds and off over milliseconds.
Mixed metal clusters (n-Bu4N)2[MoCu3OS3X3] (X = SCN, Cl and Br) were synthesized by solid state reactions. X-ray single crystal diffraction data show that the anionic clusters assume nest shaped structures. The clusters exhibit large self-defocusing effect as demonstrated by their Z-scan traces. The effective third-order polarizability of |γ| = 4.8 × 10−29 esu was determined for (n-Bu4N)2[MoCu3OS3(SCN)3] by a degenerate four-wave mixing technique with 7-ns laser pulses of 532 nm wavelength. An irradiance-dependent transmission measurement was conducted to assess the contribution of nonlinear absorption to the γ-value. These results in combination with the self-defocusing property of the cluster yielded a negative value for the real part of γ, Reγ = − 4.8 × 10−29 esu. These numerical values are in good agreement with those obtained in a Z-scan experiment. Even though the clusters absorb laser light at 532 nm significantly, the results of temporal profile analysis on transmitted pulses show that the solvent thermal effect makes little contribution to the observed nonlinear optical phenomenon.
The oxygen plasma via resists strip process cause significant damage to organic SOP, thus limiting its inter-level dielectric application. A simple treatment technology using reactive ion is proposed to reform the SOP surface. The reactive ion modification of the SOP can improve the resistance towards oxygen plasma. This is owing to the carbon atom absence in the SOP's surface area. The measurements of Fourier transform infrared (FTIR) spectroscopy, x-ray photoelectron spectroscopy (XPS), stress, thickness variation, Scanning Electron Microscope (SEM) cross-sectional view for gap filling and dielectric constant show that SOP with reactive ion treatment (RIT) has better quality for non-etch-back process than SOP without RIT.