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We investigated the microscopic mineral characteristics of modern eolian dust particulates and the trace-element compositions of the siliciclastic fractions of these samples, collected from the Philippine Sea in 2014 and 2015, and conducted an air mass backwards trajectory analysis of dust particulates in the spring and winter of 2015, to better constrain the provenances and transport dynamics of dust delivered to this region. The microscopic minerals show obvious signatures of dust deposition and physical abrasion, indicating long-distance wind transport from the Asian deserts. The trace-element compositions (Zr–Th–Sc) display a binary mixture of eolian materials derived from the eastern Asian deserts and the central Asian deserts, which is similar to the result of the Sr–Nd isotopic compositions of modern sediment trap sediments collected on the Benham Rise in 2015. We demonstrate that modern dust sediments in the Philippine Sea primarily originate from the Ordos Desert (generally > 80%), while the contributions of the Taklimakan Desert and the Badain Jaran Desert are small. Eolian dust particulates raised from source regions are predominantly transported to the Philippine Sea by the East Asian winter monsoon, but not by the westerlies. In addition, our results indicate that increased precipitation in the source regions can result in relatively low dust fluxes in the Philippine Sea, and there is a period of 6–7 days for eolian dust originating from source areas to be delivered to the Philippine Sea.
China has confirmed its ambition to join the global competition for international business dispute resolution services by establishing the China International Commercial Court (CICC). The CICC has now begun operation following a judicial interpretation issued by the Supreme People's Court. By examining the trial process of the CICC as set out by the Supreme People's Court and comparing the rules with other international commercial courts, this article provides a detailed overview and critical analysis of the issues surrounding cases brought to the CICC. Overall, compared with the approaches adopted by other international commercial courts, the approach adopted by the CICC is conservative. Without bold innovations to China's existing judicial system, the competitiveness of the CICC is likely to be limited. This article argues that it is desirable for the Court to be more actively reformed. Such reforms might also promote judicial reform in China generally and increase China's institutional competitiveness in the global business world. This article also aims to outline the challenges that parties (in particular those from overseas) may face in litigation before the CICC and provide the international community with a critical analysis of the operation and framework of the CICC.
Bearded sprangletop [Diplachne fusca (L.) P. Beauv. ex Roem. & Schult. ssp. fascicularis (Lam.) P. M. Peterson & N. Snow] is a noxious annual grass weed of paddy fields, distributed in coastal regions of the Jiangsu and Hebei provinces in China. Cyhalofop-butyl has been widely used to control grass weeds since 2006 in China. Overreliance on cyhalofop-butyl has led to the evolution of resistant weeds. In this study, the resistance level and cyhalofop-butyl resistance mechanisms were investigated in the putative resistant (JSHH) population. The dose–response experiments showed that the JSHH D. fusca population had evolved 8.9-fold resistance to cyhalofop-butyl. Acetyl-CoA carboxylase (ACCase) sequencing revealed a point mutation (GGC to GCC) at amino acid position 2096, resulting in a Gly-2096-Ala substitution in the resistant population. To our knowledge, this is the first case of cyhalofop-butyl resistance in D. fusca and the first report of a target-site mutation conferring resistance to ACCase-inhibiting herbicides in D. fusca. In addition, the resistant D. fusca population (JSHH) with the Gly-2096-Ala mutation was cross-resistant to the aryloxyphenoxypropionate herbicide metamifop, the cyclohexanedione herbicide sethoxydim, and the phenylpyrazolin herbicide pinoxaden.
Catchweed bedstraw (Galium aparine L.) is a problematic dicot weed that occurs in major winter wheat (Triticum aestivum L.) fields in China. Tribenuron-methyl has been widely used to control broadleaf weeds since 1988 in China. However, overuse has led to the resistance evolution of G. aparine to tribenuron-methyl. In this study, 20 G. aparine populations collected from Shandong and Henan provinces were used to determine tribenuron-methyl resistance and target-site resistance mechanisms. In dose–response experiments, 12 G. aparine populations showed different resistance levels (2.92 to 842.41-fold) to tribenuron-methyl compared with the susceptible population. Five different acetolactate synthase (ALS) mutations (Pro-197-Leu, Pro-197-Ser, Pro-197-His, Asp-376-Glu, and Trp-574-Leu) were detected in different resistant populations. Individuals heterozygous for Pro-197-Ser and Trp-574-Leu mutations were also observed in a resistant population (HN6). In addition, pHB4 (Pro-197-Ser), pHB7 (Pro-197-His), pHB8 (Pro-197-Leu), pHB5 (Asp-376-Glu), and pHB3 (Trp-574-Leu) subpopulations individually homozygous for specific ALS mutations were generated to evaluate the cross-resistance to ALS-inhibiting herbicides. The pHB4, pHB7, pHB8, pHB5, and pHB3 subpopulations all were resistant to sulfonylurea, pyrazosulfuron-ethyl, triazolopyrimidine, flumetsulam, sulfonylamino-carbonyl-triazolinone, flucarbazone-sodium, pyrimidinyl thiobenzoate, pyribenzoxim, and the imidazolinone imazethapyr. These results indicated the diversity of the resistance-conferring ALS mutations in G. aparine, and all these mutations resulted in broad cross-resistance to five kinds of ALS-inhibiting herbicides.
In high power laser facility for inertial confinement fusion research, final optics assembly (FOA) plays a critical role in the frequency conversion, beam focusing, color separation, beam sampling and debris shielding. The design and performance of FOA in SG-II Upgrade laser facility are mainly introduced here. Due to the limited space and short focal length, a coaxial aspheric wedged focus lens is designed and applied in the FOA configuration. Then the ghost image analysis, the focus characteristic analysis, the B integral control design and the optomechanical design are carried out in the FOA design phase. In order to ensure the FOA performance, two key technologies are developed including measurement and adjustment technique of the wedged focus lens and the stray light management technique based on ground glass. Experimental results show that the design specifications including laser fluence, frequency conversion efficiency and perforation efficiency of the focus spot have been achieved, which meet the requirements of physical experiments well.
The Shen-Guang II Upgrade (SG-II-U) laser facility consists of eight high-power nanosecond laser beams and one short-pulse picosecond petawatt laser. It is designed for the study of inertial confinement fusion (ICF), especially for conducting fast ignition (FI) research in China and other basic science experiments. To perform FI successfully with hohlraum targets containing a golden cone, the long-pulse beam and cylindrical hohlraum as well as the short-pulse beam and cone target alignment must satisfy tight specifications (30 and
rms for each case). To explore new ICF ignition targets with six laser entrance holes (LEHs), a rotation sensor was adapted to meet the requirements of a three-dimensional target and correct beam alignment. In this paper, the strategy for aligning the nanosecond beam based on target alignment sensor (TAS) is introduced and improved to meet requirements of the picosecond lasers and the new six LEHs hohlraum targets in the SG-II-U facility. The expected performance of the alignment system is presented, and the alignment error is also discussed.
We describe an integrated navigation system based on Global Navigation Satellite Systems (GNSS), an Inertial Navigation System (INS) and terrestrial ranging technologies that can support accurate and seamless indoor-outdoor positioning. To overcome severe multipath disturbance in indoor environments, Locata technology is used in this navigation system. Such a “Locata-augmented” navigation system can operate in different positioning modes in both indoor and outdoor environments. In environments where GNSS is unavailable, e.g. indoors, the proposed system is designed to operate in the Locata/INS “loosely-integrated” mode. On the other hand, in outdoor environments, all GNSS, Locata and INS measurements are available, and all useful information can be fused via a decentralised Federated Kalman filter. To evaluate the proposed system for seamless indoor-outdoor positioning, an indoor-outdoor test was conducted at a metal-clad warehouse. The test results confirmed that the proposed navigation system can provide continuous and reliable position and attitude solutions, with the positioning accuracy being better than five centimetres.
Dietary intake of PUFA has been associated with colorectal neoplasm risk; however, results from observational studies have been inconsistent. Most prior studies have utilised self-reported dietary measures to assess fatty acid exposure which might be more susceptible to measurement error and biases compared with biomarkers. The purpose of this study was to determine whether erythrocyte phospholipid membrane PUFA percentages are associated with colorectal adenoma risk. We included data from 904 adenoma cases and 835 polyp-free controls who participated in the Tennessee Colorectal Polyp Study, a large colonoscopy-based case–control study. Erythrocyte membrane PUFA percentages were measured using GC. Conditional logistic regression was used to calculate adjusted OR for risk of colorectal adenomas with erythrocyte membrane PUFA. Higher erythrocyte membrane percentages of arachidonic acid was associated with an increased risk of colorectal adenomas (adjusted OR 1·66; 95 % CI 1·05, 2·62, Ptrend=0·02) comparing the highest tertile to the lowest tertile. The effect size for arachidonic acid was more pronounced when restricting the analysis to advanced adenomas only. Higher erythrocyte membrane EPA percentages were associated with a trend towards a reduced risk of advanced colorectal adenomas (Ptrend=0·05). Erythrocyte membrane arachidonic acid percentages are associated with an increased risk of colorectal adenomas.
In this paper, we propose to use the interior functions of an hierarchical basis for high order BDMp elements to enforce the divergence-free condition of a magnetic field B approximated by the H(div)BDMp basis. The resulting constrained finite element method can be used to solve magnetic induction equation in MHD equations. The proposed procedure is based on the fact that the scalar (p–1)-th order polynomial space on each element can be decomposed as an orthogonal sum of the subspace defined by the divergence of the interior functions of the p-th order BDMp basis and the constant function. Therefore, the interior functions can be used to remove element-wise all higher order terms except the constant in the divergence error of the finite element solution of the B-field. The constant terms from each element can be then easily corrected using a first order H(div) basis globally. Numerical results for a 3-D magnetic induction equation show the effectiveness of the proposed method in enforcing divergence-free condition of the magnetic field.
The effect of fruit and vegetable intake on breast cancer prognosis is controversial. Thus, a meta-analysis was carried out to explore their associations. A comprehensive search was conducted in PubMed, Web of Science, OVID, ProQuest and Chinese databases from inception to April 2016. The summary hazard ratios (HR) and 95 % CI were estimated using a random effects model if substantial heterogeneity existed and using a fixed effects model if not. Subgroup analyses and sensitivity analyses were also performed. In total, twelve studies comprising 41 185 participants were included in the meta-analysis. Comparing the highest with the lowest, the summary HR for all-cause mortality were 1·01 (95 % CI 0·72, 1·42) for fruits and vegetables combined, 0·96 (95 % CI 0·83, 1·12) for total vegetable intake, 0·99 (95 % CI 0·89, 1·11) for cruciferous vegetable intake and 0·88 (95 % CI 0·74, 1·05) for fruit intake; those for breast cancer-specific mortality were 1·05 (95 % CI 0·77, 1·43) for total vegetable intake and 0·94 (95 % CI 0·69, 1·26) for fruit intake; and those for breast cancer recurrence were 0·89 (95 % CI 0·53, 1·50) for total vegetable intake and 0·98 (95 % CI 0·76, 1·26) for cruciferous vegetable intake. This meta-analysis found no significant associations between fruit and vegetable intake and breast cancer prognosis.
We present a high-order discontinuous Galerkin (DG) method for the time domain Maxwell's equations in three-dimensional heterogeneous media. New hierarchical orthonormal basis functions on unstructured tetrahedral meshes are used for spatial discretization while Runge-Kutta methods for time discretization. A uniaxial perfectly matched layer (UPML) is employed to terminate the computational domain. Exponential convergence with respect to the order of the basis functions is observed and large parallel speedup is obtained for a plane-wave scattering model. The rapid decay of the out-going wave in the UPML is shown in a dipole radiation simulation. Moreover, the low frequency electromagnetic fields excited by a horizontal electric dipole (HED) and a vertical magnetic dipole (VMD) over a layered conductive half-space and a high frequency ground penetrating radar (GPR) detection for an underground structure are investigated, showing the high accuracy and broadband simulation capability of the proposed method.
Petroleum coke (PC) is a low-cost and potential carbon source for electrochemical energy storage. To expand the utilization of PC in supercapacitor, PC-based activated carbons (PCACs) with heteroatoms-doped were prepared from PC by KOH chemical activation. The as-prepared carbon exhibited a high surface area (2326.4 m2/g) and hierarchical micro-mesoporous structure, resulting in a high specific capacitance (421 F/g at 1 A/g) and excellent rate performance in KOH electrolyte (217 F/g at 50 A/g). Meanwhile, to improve the high-rate capacitive performance of PCACs in H2SO4 electrolyte, functionalized activated carbon (HQ/PCAC-4) was prepared by physically adsorbing the hydroquinone (HQ) on PCACs. The HQ/PCAC-4 showed an unprecedented capacitance value of 300.2 F/g even at an ultrahigh current density of 50 A/g. In addition, the energy density of HQ/PCAC-4 in H2SO4 electrolyte reached 19.5 W h/kg. The high energy density and excellent rate performance ensured their prosperous application in high-power energy storage system.
In this paper, we present accurate and economic integration quadratures for hypersingular functions over three simple geometric shapes in ℝ3 (spheres, cubes, and cylinders). The quadrature nodes are made of the tensor-product of 1-D Gauss nodes on [–1,1] for non-periodic variables or uniform nodes on [0,2π] or [0,π] for periodic ones. The quadrature weights are converted from a brute-force integration of the hypersingular function through interpolating the smooth component of the integrand. Numerical results are presented to validate the accuracy and efficiency of computing hypersingular integrals, as in the computations of Cauchy principal values, with a minimum number of quadrature nodes. The pre-calculated quadrature tables can be then readily used to implement Nyström collocation methods of hypersingular volume integral equations such as the one for Maxwell equations.
A diode-pumped alkali vapor laser (DPAL) is one of the most promising candidates of the next-generation high-powered laser source. As the saturated number density of alkali vapor is highly dependent on the temperature inside a vapor cell, the temperature distribution in the cross-section of a cell will greatly affect the homogeneity of a laser medium and the output characteristics of a DPAL. In this paper, we developed an algorithm based on the regime concluding quasi-Hilbert transform to evaluate the phase aberration of a wavefront when the probe beam passes through the vapor cell placed in one arm of a Mach–Zehnder interference setup. According to the theoretical algorithm, we deduced the temperature distribution of a cesium vapor cell for different heating conditions. The study is thought to be useful for development of a high-powered laser.
A diode-pumped alkali laser (DPAL) provides the significant promise for high-powered performances. In this paper, a mathematical model is introduced for examination of the kinetic processes of a diode-pumped cesium vapor hollow-core photonic-crystal fiber (HC-PCF) laser, in which the cesium vapor is filled in the center hole of a photonic-bandgap fiber instead of a glass cell. The influence of deleterious processes including energy pooling, photo-ionization, and Penning ionization on the physical features of a fiber DPAL is studied in this report. It has been theoretically demonstrated that the deleterious processes cannot be ignored in a high-powered fiber-DPAL system.
Phosphorene is a new-emerging two-dimensional material with many fascinating electronic and thermal properties. Using nonequilibrium Green's function technique, we investigate the thermoelectric transport properties of phosphorene in the ballistic transport regime. We find that while the electronic conductance and thermal conductance of phosphorene are highly anisotropic, the Seebeck coefficient is isotropic. The maximum predicted thermopower reaches 2500 μV/K. We also find that the Wiedemann–Franz law is valid only when the chemical potential is inside valence band or conduction band. When the chemical potential is near the valence band maximum or conduction band minimum; however, the Wiedemann–Franz law becomes invalid, and interestingly, the figure of merit ZT reaches its maximum value. We also find that figure of merit ZT increases with the increase of temperature, and ZT in the armchair direction is much higher than that in the zigzag direction. By analyzing the various effects on ZT, we discuss the possible routines to enhance figure of merit ZT.
Point defects are imperfections in a crystal that are confined to atomic dimensions in all three directions. Depending on the chemical species involved, point defects can be considered as either intrinsic or extrinsic. Intrinsic point defects include vacancies, i.e. missing atoms, and self-interstitials, i.e. extra atoms having the same chemical species as the host crystal. Extrinsic point defects, on the other hand, are atoms having a different chemical species from the host crystal that they enter. Such point defects are often called impurity or solute atoms. Impurities usually refer to “unwanted” foreign atoms in a crystal, while solute atoms are often intentionally introduced into the crystal to alter its properties.
Point defects have a profound effect on the properties of engineering crystalline materials, either by themselves, or through their interactions with dislocations (line defects) and grain boundaries (planar defects). An example of the former situation is the semiconductor industry, whose success hinges on their ability to control the electronic properties of silicon by selective doping, through which transistors and integrated circuits can be made. An example of the latter situation is solid solution hardening, in which the elastic distortion around point defects allow them to interact with dislocations and alter the mechanical strength of the crystalline material.
In the following four chapters, we focus on the fundamental mechanics and thermodynamic principles that are needed to understand how point defects influence material properties. In Chapter 4, we study the stress and strain fields around point defects, using the elasticity theory introduced in Chapter 2. These results lead to an estimate of the energy cost of introducing point defects, as well as how point defects interact with each other and with other types of defects (e.g. dislocations) to be introduced later. In Chapter 5, the energy cost of introducing point defects is combined with the statistical thermodynamic principles of Chapter 3, to predict the concentration of point defects in a crystal at thermal equilibrium. It will be seen that, due to the entropic gain in allowing point defects, the equilibrium concentration of point defects in a crystal at finite temperature is never zero.
The perfect crystal structure is an idealization of the atomic arrangements in real crystalline materials. After a brief introduction of several common perfect crystal structures, we start our study of imperfections in crystals with some remarks about why so much attention is focused on these defects. The central reason is that perfect crystals, without imperfections, would be relatively uninteresting materials, without most of the useful properties with which we are all familiar.We consider some of the physical properties that crystals would have or not have if they were perfect. Through this thought experiment, we show that most of the useful engineering properties of crystalline materials are defect controlled and thus depend on the properties and behavior of imperfections.
Perfect crystal structures
Single crystals and polycrystals
The word “crystal” usually brings to mind large mineral (e.g. quartz) blocks on display in museums, or the shiny diamond on a wedding ring. Their faceted surfaces and often distinct geometric shape give rise to a sense of beauty not found in other more “common” materials. As an example, Fig. 1.1a shows a photograph of a ruby crystal. However, crystalline materials are easily found in our everyday life. In fact, most engineering materials are crystalline. Metals, semiconductors, and ceramics are all crystalline materials, even though they may not have faceted surfaces.
The distinction between a large ruby crystal and an engineering metallic alloy is that the former is a single crystal and the latter is usually a polycrystal. A polycrystal is an aggregate of many small single crystals (called grains), each with a different orientation. As an example, Fig. 1.1b shows a micrograph of a nickel-based superalloy (where the word “super” refers to its superior mechanical properties). The size of each single crystal grain in this superalloy is on the order of 10 to 100 micrometers (μm), too small to be seen by the naked eye. That is why the shape of a piece of metal does not seem faceted to the eye; the facets can be observed with the aid of a microscope.