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Multidimensional instabilities always develop with time during the process of radiation pressure acceleration, and are detrimental to the generation of monoenergetic proton beams. In this paper, a sharp-front laser is proposed to irradiate a triple-layer target (the proton layer is set between two carbon ion layers) and studied in theory and simulations. It is found that the thin proton layer can be accelerated once to hundreds of MeV with monoenergetic spectra only during the hole-boring (HB) stage. The carbon ions move behind the proton layer in the light-sail (LS) stage, which can shield any further interaction between the rear part of the laser and the proton layer. In this way, proton beam instabilities can be reduced to a certain extent during the entire acceleration process. It is hoped such a mechanism can provide a feasible way to improve the beam quality for proton therapy and other applications.
We present a study on the interaction between wind and water waves with a broad-band spectrum using wave-phase-resolved simulation with long-term wave field evolution. The wind turbulence is computed using large-eddy simulation and the wave field is simulated using a high-order spectral method. Numerical experiments are carried out for turbulent wind blowing over a wave field initialised using the Joint North Sea Wave Project spectrum, with various wind speeds considered. The results show that the waves, together with the mean wind flow and large turbulent eddies, have a significant impact on the wavenumber–frequency spectrum of the wind turbulence. It is found that the shear stress contributed by sweep events in turbulent wind is greatly enhanced as a result of the waves. The dependence of the wave growth rate on the wave age is consistent with the results in the literature. The probability density function and high-order statistics of the wave surface elevation deviate from the Gaussian distribution, manifesting the nonlinearity of the wave field. The shape of the change in the spectrum of wind-waves resembles that of the nonlinear wave–wave interactions, indicating the dominant role played by the nonlinear interactions in the evolution of the wave spectrum. The frequency downshift phenomenon is captured in our simulations wherein the wind-forced wave field evolves for
peak wave periods. Using the numerical result, we compute the universal constant in a wave-growth law proposed in the literature, and substantiate the scaling of wind–wave growth based on intrinsic wave properties.
As rarely large flake graphite (9 mesh) was recently exploited in China, it was innovatively developed as the raw material to prepare a novel wound dressing based on large expanded graphite (EG) in this work. The EG worms were prepared in an easy oxidative intercalation and thermal expansion method. Afterward, chitosan was grafted onto the surface of EG by chemical modification, forming CS-EG worms. CS-EG sponge dressings were then obtained by pressing a number of CS-EG worms together by external force. Due to the porous structure and large specific surface area, the produced CS-EG sponges exhibited outstanding adsorption capacity for wound exudate. They could also promote blood coagulation by adsorbing the blood cells and proteins quickly and effectively, showing excellent hemostatic performance. The eminent performances and the simple preparation process ensure the great application potential of CS-EG as a dressing material. This is also the first time to report the application of the traditional carbon material, EG, to act as a dressing material after chemical modification.
Combining density functional theory calculations and temperature programmed desorption (TPD) experiments, the adsorption behavior of various sulfur containing compounds, including C2H5SH, CH3SCH3, tetrahydrothiophene, thiophene, benzothiophene, dibenzothiophene, and their derivatives on the coordinately unsaturated sites of Mo27Sx model nanoparticles, are studied systematically. Sulfur molecules with aromaticity prefer flat adsorption than perpendicular adsorption. The adsorption of nonaromatic molecules is stronger than the perpendicular adsorption of aromatic molecules, but weaker than the flat adsorption of them. With gradual hydrogenation (HYD), the binding affinity in the perpendicular adsorption modes increases, while in flat adsorption modes it increases first, then decreases. Significant steric effects on the adsorption of dimethyldibenzothiophene were revealed in perpendicular adsorption modes. The steric effect, besides weakening adsorption, could also activate the S–C bonds through a compensation effect. Finally, by comparing the theoretical adsorption energies with the TPD results, we suggest that HYD and direct-desulfurization path may happen simultaneously, but on different active sites.
Given the global water challenges, solar-driven steam generation has become a renewed topic recently as an energy-efficient way for clean water production. Here, a hybrid plasmonic structure consisting of a top layer of TiN nanoparticles (NPs) and a bottom layer of mesoporous anodized alumina membrane (AAM) was rationally designed and fabricated. The top TiN NPs with broadband light absorption acted as a plasmonic heating layer, which converted the absorbed light to heat efficiently for interfacial water heating. The AAM acted as the mechanical support layer, guaranteeing the heat isolation and continuous water replenishment. With optimized thickness of the TiN top layer, a solar steam generation efficiency of 87.7% was achieved in this study. This efficiency is comparable or even higher than prior studies. The current work proves the capability of the TiN NPs as an alternative photothermal material.
Tsangpoite, ideally Ca5(PO4)2(SiO4), the hexagonal polymorph of silicocarnotite, and matyhite, ideally Ca9(Ca0.5□0.5)Fe(PO4)7, the Fe-analogue of Ca-merrillite, were identified from the D'Orbigny angrite meteorite by electron probe microanalysis, electron microscopy and micro-Raman spectroscopy. On the basis of electron diffraction, the symmetry of tsangpoite was shown to be hexagonal, P63/m or P63, with a = 9.489(4) Å, c = 6.991(6) Å, V = 545.1(6) Å3 and Z = 2 for 12 oxygen atoms per formula unit, and that of matyhite was shown to be trigonal, R3c, with a = 10.456 (7) Å, c = 37.408(34) Å, V = 3541.6 (4.8) Å3 and Z = 6 for 28 oxygen atoms per formula unit. On the basis of their constant association with the grain-boundary assemblage: Fe sulfide + ulvöspinel + Al–Ti-bearing hedenbergite + fayalite–kirschsteinite intergrowth, the formation of tsangpoite and matyhite, along with kuratite (the Fe-analogue of rhönite), can be readily rationalised as crystallisation from residue magmas at the final stage of the D'Orbigny meteorite formation. Alternatively, the close petrographic relations between tsangpoite/matyhite and the resorbed Fe sulfide rimmed by fayalite + kirschsteinite symplectite, such as the nucleation of tsangpoite in association with magnetite ± other phases within Fe sulfide and the common outward growth of needle-like tsangpoite or plate-like matyhite from the fayalite–kirschsteinite symplectic rim of Fe sulfide into hedenbergite, infer that these new minerals and the grain-boundary assemblage might represent metasomatic products resulting from reactions between an intruding metasomatic agent and the porous olivine–plagioclase plate + fayalite-kirschsteinite overgrowth + augite + Fe sulfide aggregates. Still further thermochemical and kinetics evidence is required to clarify the exact formation mechanisms/conditions of the euhedral tsangpoite, matyhite and kuratite at the grain boundary of the D'Orbigny angrite.
Sexual offenses cause harm to the victims’ physical and psychological functions. This study was conducted to evaluate the risk of incident psychiatric disorders in sexual assault victims. Taiwan’s National Health Insurance Research Database was used to conduct a nationwide population-based cohort study to assess the risk of incident psychiatric disorders in sexual assault victims and to further evaluate the respective risk estimates on the basis of diagnostic patterns. A total of 81 sexual assault victims and 324 controls matched by sex, age and residential area were included. The mean age of the sexual assault victims was 18.39 (sd 10.23) years, and 93.83% (76/81) of the sample were females. Sexual assault victims had a higher incidence density of psychiatric disorders than did the control group (9.2% per year, 95% confidence interval [CI] 1.1–33.2% per year v. 1.1% per year, 95% CI .4–15.7% per year; p=.037). Sexual assault was an independent risk factor for incident psychiatric disorders, with an incidence rate ratio of 3.40 (95% CI 1.04–26.41) after adjustment for potential confounding factors. Assessment of psychiatric disorders should be implemented in the integrative care of sexual assault victims. Physicians providing clinical care to the sexual assault victims should receive more all-round training to understand and manage this type of violence.
A 336-cm-long sediment core spanning the last 130 ka was recovered from Lake Xingkai on the northeastern margin of the East Asian summer monsoon domain to reveal the linkage between lacustrine depositional processes and environmental changes. Bayesian end member modeling analysis was conducted to partition and interpret the grain-size distributions of Lake Xingkai sediments. Our results suggest that the sedimentary system is characterized by three end members (EMs). EM1 and EM2, with a modal value of 13 and 10 μm, respectively, indicate the variation of local hydraulic conditions. EM3, with a modal value of 5 μm, reflects the background atmospheric dust loading. High atmospheric dust concentration generally occurred during Marine Isotope Stage (MIS) 5d, MIS 4, and early MIS 3, when the climate in the Asian dust source region was cold and dry. In contrast, low dust concentration prevailed during MIS 2, likely due to the southward shift of the westerlies driven by maximum ice volume in the high latitudes.
The microstructural evolution of precipitation in two model alloys, Fe–NiAl and Fe–NiAl–Cu, was investigated during aging at 500°C for different times using atom probe tomography (APT). The APT results reveal that the addition of Cu effectively increases the number density of NiAl precipitates. This is attributed to Cu promoting the nucleation of NiAl particles by increasing the chemical driving force and decreasing the interfacial energy. The NiAl precipitates of the Fe–NiAl–Cu alloy grow and coarsen at a slower rate than that of the Fe–NiAl alloy, mainly due to the slower diffusion rate of the Cu atoms. The mechanical properties of the two alloys were characterized by Vickers hardness and tension tests. It was found that the addition of Cu results in the formation of core–shell precipitates with a Cu-rich core and a NiAl shell, leading to a dramatic improvement of peak hardness and strength. The effect of Cu on precipitation strengthening is discussed in terms of chemical strength and coherency strength.
High coherence of the laser is indispensable light sources in modern long or short-distance imaging systems, because the high coherence leads to coherent artifacts such as speckle that corrupt image formation. To deliver low coherence pulses in fiber amplifiers, we utilize the superluminescent pulsed light with broad bandwidth, nonlongitudinal mode structure and chaotic mode phase as the seed source of the cascaded fiber amplifiers. The influence of fiber superluminescent pulse amplification (SPA) on the limitations of the performance is analyzed. A review of our research results for SPA in the fibers are present, including the nonlinear theories of this low coherent light sources, i.e., self-focusing (SF), stimulated Raman scattering (SRS) and self-phase modulation (SPM) effects, and the experiment results of the nanosecond pulses with peak power as high as 4.8 MW and pulse energy as much as 55 mJ. To improve the brightness of SPA light in the future work, we introduce our novel evaluation term and a more reasonable criterion, which is denoted by a new parameter of brightness factor for active large mode area fiber designs. A core-doped active large pitch fiber with a core diameter of
and a mode-field diameter of
is designed by this method. The designed fiber allows near diffracted limited beam quality operation, and it can achieve 100 mJ pulse energy and 540 W average power by analyzing the mode coupling effects induced by heat.
Environmental filtering and competitive interactions are important ecological processes in community assembly. The contribution of the two processes to community assembly can be evaluated by shifts in functional diversity patterns. We examined the correlations between functional diversity of six traits (leaf chlorophyll concentration, dry matter content, size, specific leaf area, thickness and wood density) and environmental gradients (topography and soil) for 92 species in the 20-ha Dinghushan forest plot in China. A partial Mantel test showed that most of the community-weighted mean trait values changed with terrain convexity and soil fertility, which implied that environmental filtering was occurring. Functional diversity of many traits significantly increased with increasing terrain convexity and soil fertility, which was associated with increased light and below-ground resources respectively. These results suggest that co-occurring species are functionally convergent in regions of strong abiotic stress under the environmental filtering, but functionally divergent in more benign environments due to resource partitioning and competitive interactions. Single-trait diversity and multivariate functional diversity had different relationships with environmental factors, indicating that traits were related to different niche axes, and associated with different ecological processes, which demonstrated the importance of focusing niche axes in traits selection. Between 9% and 41% of variation in functional diversity of different traits was explained by environmental factors in stepwise multiple regression models. Terrain convexity and soil fertility were the best predictors of functional diversity, which contributed 30.5% and 29.0% of total R2 to the model. These provided essential evidence that different environmental factors had distinguishing impacts on regulating diversity of traits.
With the 3D data of SDSS-IV MaNGA (Bundy et al. 2015) spectra and multi-wavelength SED modeling, we expect to have a better understanding of the distribution of dust, gas and star formation of galaxy mergers. For a case study of the merging galaxy Mrk848, we use both UV-to-IR broadband SED and the MaNGA integral field spectroscopy to obtain its star formation histories at the tail and core regions. From the SED fitting and full spectral fitting, we find that the star formation in the tail regions are affected by the interaction earlier than the core regions. The core regions show apparently two times of star formation and a strong burst within 500Myr, indicating the recent star formation is triggered by the interaction. The star formation histories derived from these two methods are basically consistent.
Recent progress on rare-earth doped polycrystalline YAG transparent ceramics has made them an alternative novel solid-state laser gain material. In this paper we present results of our research on polycrystalline RE:YAG transparent ceramics. High optical quality YAG ceramics doped with various rare-earth (RE) ions such as
have been successfully fabricated using the solid-state reactive sintering method. Highly efficient laser oscillations of the fabricated ceramics are demonstrated.
Quality control of the inertial confinement fusion (ICF) target in the laser fusion program is vital to ensure that energy deposition from the lasers results in uniform compression and minimization of Rayleigh–Taylor instabilities. The technique of nuclear microscopy with ion beam analysis is a powerful method to provide characterization of ICF targets. Distribution of elements, depth profile, and density image of ICF targets can be identified by particle-induced X-ray emission, Rutherford backscattering spectrometry, and scanning transmission ion microscopy. We present examples of ICF target characterization by nuclear microscopy at Fudan University in order to demonstrate their potential impact in assessing target fabrication processes.
The manner in which technological capability and marketing capability can be successfully leveraged is an important research issue. Based on the resource-management model, this study aims to answer two research questions: (1) whether technological capability and marketing capability are complementary or supplementary capabilities; and (2) how technological capability and marketing capability can be used appropriately to respond to environmental turbulence. Based on a face-to-face interview survey of 212 Chinese firms, we find that technological capability and marketing capability have synergistic effects. We also find that technological turbulence enhances the performance effect of technological capability, but impedes that of marketing capability; whereas market turbulence advances the performance effect of marketing capability, but impedes that of technological capability. Thus, the appropriate way to leverage technological capability and marketing capability is to integrate them and to deploy technological capability to respond to technological turbulence and marketing capability to respond to market turbulence.
Phase structures and electrical properties of lead-free piezoelectric (1−x)(Bi0.5Na0.5)TiO3–x(K0.5Na0.5)NbO3 (BNT–xKNN) ceramics with 0.08 ≤ x ≤ 0.19 were systematically investigated. Results showed that a phase transition from a tetragonal to a pseudocubic phase occurred in this system, as KNN content increases. The addition of KNN shifted both the depolarization temperature Td and rhombohedral–tetragonal phase transition temperature TR-T to lower temperatures and tended to enhance the relaxor behavior of the ceramics, which was well explained by the microdomain–macrodomain transition theory with calculating criterion K. At x = 0.10–0.11, Td reached room temperature (RT), which accordingly induced an enhancement of the unipolar strain that peaks at a value of 0.22% was obtained. Furthermore, as the compositions (x = 0.12–0.15) have Td below RT, samples exhibited high electrostrictive response with large electrostrictive coefficient Q33 (0.017–0.019 m4/C2) and good thermostability comparable with that of traditional Pb-based electrostrictors.
Tracheobronchial compression of cardiovascular origin is an uncommon and frequently unrecognised cause of respiratory distress in children. The compression may be due to encircling vessels or dilated neighbouring cardiovascular structures. Bronchoscopy and detailed radiography, especially computed tomography and magnetic resonance imaging, are among the most powerful diagnostic tools. Few previous reports have addressed the relationship between bronchoscopic findings and underlying cardiovascular anomalies. The objective of this study was to correlate bronchoscopic and radiographic findings in children with cardiovascular-associated airway obstruction. A total of 41 patients were recruited for the study. Patients with airway obstruction were stratified on the basis of the aetiology of the cardiovascular structures and haemodynamics into an anatomy-associated group and a haemodynamics-associated group. In the anatomy-associated group, stenosis and malacia were found with comparable frequency on bronchoscopy, and the airway obstructions were mostly found in the trachea (71% of patients). In the haemodynamics-associated group, malacia was the most common bronchoscopic finding (85% of patients), and nearly all locations of airway involvement were in the airway below the carina (90% of patients). The tracheal compression was usually caused by aberrant systemic branching arteries in the anatomy-associated group. In the haemodynamics-associated group, the causal relationships varied. Tracheal compression was often caused by lesions of the main pulmonary artery and aorta, whereas obstruction of the right main bronchus was caused by lesions of the main pulmonary artery and right pulmonary artery. The causes of left main bronchus compression were more diverse. In summary, the bronchoscopic presentations and locations are quite different between these two groups.
More than forty years ago, Erdős conjectured that for any , every k-uniform hypergraph on n vertices without t disjoint edges has at most max edges. Although this appears to be a basic instance of the hypergraph Turán problem (with a t-edge matching as the excluded hypergraph), progress on this question has remained elusive. In this paper, we verify this conjecture for all . This improves upon the best previously known range , which dates back to the 1970s.
Treatment with a combination of four nutrients, i.e. R-α-lipoic acid, acetyl-l-carnitine, nicotinamide and biotin, just as with pioglitazone, significantly improves glucose tolerance, insulin release, plasma NEFA, skeletal muscle mitochondrial biogenesis and oxidative stress in Goto–Kakizaki (GK) rats. However, it is not known whether treatment with these nutrients can improve mitochondrial function and reduce oxidative stress in GK rats. The effects of a combination of these four nutrients on mitochondrial function, oxidative stress and apoptosis in GK rat liver were investigated. Livers of untreated GK rats showed (1) abnormal changes in the activities of mitochondrial complexes (decreases in I, III and IV and increases in II and V), (2) increases in protein oxidation, (3) decreases in antioxidant enzymes (superoxide dismutase, glutathione S-transferase, NADH-quinone oxidoreductase-1), (4) a decrease in total antioxidant capacity but increases in reduced glutathione level and glyceraldehyde 3-phosphate dehydrogenase expression and (5) significant increases in apoptosis biomarkers, including expression of p21 and p53. A 3-month treatment with the four nutrients significantly improved most of these abnormalities in GK rats, and the effects of the nutrient combination were greater than those of pioglitazone for most of these indices. These results suggest that dietary supplementation with nutrients that are thought to influence mitochondrial function may be an effective strategy for improving liver dysfunction in GK diabetic rats.