We report the unified constitutive law of vibroconvective turbulence in microgravity, i.e. $Nu \sim a^{-1} Re_{os}^\beta$ where the Nusselt number $Nu$ measures the global heat transport, $a$ is the dimensionless vibration amplitude, $Re_{os}$ is the oscillational Reynolds number and $\beta$ is the universal exponent. We find that the dynamics of boundary layers plays an essential role in vibroconvective heat transport and the $Nu$-scaling exponent $\beta$ is determined by the competition between the thermal boundary layer (TBL) and vibration-induced oscillating boundary layer (OBL). Then a physical model is proposed to explain the change of scaling exponent from $\beta =2$ in the TBL-dominant regime to $\beta = 4/3$ in the OBL-dominant regime. Our finding elucidates the emergence of universal constitutive laws in vibroconvective turbulence, and opens up a new avenue for generating a controllable effective heat transport under microgravity or even microfluidic environment in which the gravity effect is nearly absent.

Montmorillonite (Mnt)-based solid acids have a wide range of applications in catalysis and adsorption of pollutants. For such solid acids, the acidic characteristic often plays a significant role in these applications. The objective of the current study was to examine the effects of H3PO4-activation and supporting WO3 on the textural structure and surface acidic properties of Mnt. The Mnt-based solid acid materials were prepared by H3PO4 treatment and an impregnation method with a solution of ammonium metatungstate (AMT) and were examined as catalysts in the dehydration of glycerol to acrolein. The catalysts were characterized by nitrogen adsorption-desorption, powder X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, scanning electronic microscopy (SEM), X-ray photoelectron spectroscopy (XPS), diffuse reflectance ultraviolet-visible (DR UV-Vis) spectroscopy, temperature programmed desorption of NH3 (NH3-TPD), diffuse reflectance Fourier-transform infrared (DR FTIR) spectroscopy of adsorbed pyridine, and thermogravimetric (TG) analyses. The phosphoric acid treatment of Mnt created Brönsted and Lewis acid sites and led to increases in specific surface areas, porosity, and acidity. WO3 species influenced total acidity, acid strength, the numbers of Brönsted and Lewis acid sites, and catalytic performances. A high turnover frequency (TOF) value (31.2 h−1) based on a maximal 60.7% yield of acrolein was reached. The correlation of acrolein yield with acidic properties indicated that the cooperative role of Brönsted and Lewis acid sites was beneficial to the formation of acrolein and a little coke deposition (<3.3 wt.%). This work provides a new idea for the design of solid acid catalysts with cooperative Brönsted and Lewis acidity for the dehydration of glycerol.

Fast neutron absorption spectroscopy is widely used in the study of nuclear structure and element analysis. However, due to the traditional neutron source pulse duration being of the order of nanoseconds, it is difficult to obtain a high-resolution absorption spectrum. Thus, we present a method of ultrahigh energy-resolution absorption spectroscopy via a high repetition rate, picosecond duration pulsed neutron source driven by a terawatt laser. The technology of single neutron count is used, which results in easily distinguishing the width of approximately 20 keV at 2 MeV and an asymmetric shape of the neutron absorption peak. The absorption spectroscopy based on a laser neutron source has one order of magnitude higher energy-resolution power than the state-of-the-art traditional neutron sources, which could be of benefit for precisely measuring nuclear structure data.

Late Paleozoic strata in the southeastern Ordos Basin comprise targeted reservoirs for tight gas exploration. As a typical intracratonic basin, the Ordos Basin is characterized by low-accommodation space and a complex sediment infilling process, which attracts much attention. During the early Permian, the southeast area was fed by sediments from multiple sediment sources, which makes it difficult to identify the pinch-out of the sand bodies and reconstruct the sediment routing system. In this study, we reconstruct the paleo-topography of the late Paleozoic setting using high-resolution 2D and 3D seismic data. Thus, we identify two types of topography: the eastern block is presented as a semiclosed depression, and the western block is observed as a flat platform. Based on detrital zircon U–Pb data and heavy mineral assemblages, we reconstruct the provenance area and show that early Permian sediments originate from the northern margin of the Ordos Basin and from the northern Qinling orogenic belt in the south. By integrating the trace element contents, carbon and oxygen isotope data and sedimentary structure from core samples, we can observe the paleoenvironment and the corresponding facies associations in these blocks. The eastern block was infilled by a prograding delta; the western block was infilled by a tide-dominated delta or a wavy-dominated delta. By using stratigraphic forward modelling, we find that most sediments in the semiclosed setting are progradational and intensely interacted. In contrast, the sediments in the western block present an open setting, infilled and gently interacted. The fine-grained deposits were not easily preserved due to tidal or wave reworking processes in the shallow-water marine setting, and they were transported into deep-water areas. Furthermore, to explore the dominant factors in a pattern of fluvial–deltaic sand bodies formed in the low-accommodation basin, we rebuild the sediment routing system parameters and plot them on a bubble chart. According to the fitness between the depositional volume and the above parameters, we determine the key factors in the routing systems that formed. The results show that the sediment supply has a high relevance to the depositional volume in a semiclosed setting, such as the eastern block, while the terrain height may drive sedimentation in an open marine setting, such as the western block. We demonstrate that two different infill patterns and different sand-body stacking patterns with multiple sediment sources in a low-accommodation basin may serve as a model for similar settings.

The transport phenomena of dust particles have been widely observed in fusion plasmas. In this article, we report the observations of dust fragmentations in the Experimental Advanced Superconducting Tokamak (EAST). A dust particle splits into two daughter particles and their motions are recorded before and after the breakup with a fast video camera. The trajectories of the daughter particles in the experiment are consistent with equation-of-motion simulations. The stability of a rotating charged particle in the plasma is briefly discussed.

We report that vertical vibration with small amplitude and high frequency can tame convective heat transport in Rayleigh–Bénard convection in a turbulent regime. When vertical vibration is applied, a dynamically averaged ‘anti-gravity’ results that stabilizes the thermal boundary layer and inhibits the eruption of thermal plumes. This eventually leads to the attenuation of the intensity of large-scale mean flow and a significant suppression of turbulent heat transport. Accounting for both the thermally led buoyancy and the vibration-induced anti-gravitational effects, we propose an effective Rayleigh number that helps to extend the Grossmann–Lohse theory to thermal vibrational turbulence. The prediction of the reduction on both the Nusselt and Reynolds numbers obtained by the extended model is found to agree well with the numerical data. In addition, vibrational influences on the mean flow structure and the temporal evolution of Nusselt and Reynolds numbers are investigated. The non-uniform characteristic of vibration-induced ‘anti-gravity’ is discussed. The present findings provide a powerful basis for studying thermal vibrational turbulence and put forward a novel strategy for actively controlling thermal turbulence.

In this paper, we report that reversals of the large-scale circulation in two-dimensional Rayleigh–Bénard (RB) convection can be suppressed by imposing sinusoidally distributed heating to the bottom plate. We examine how the frequency of flow reversals depends on the dimensionless wavenumber $k$ of the spatial temperature modulation with various modulation amplitude $A$. For sufficiently large $k$, the flow reversal frequency is close to that in the standard RB convection under uniform heating. However, when $k$ decreases, the frequency of flow reversal gradually becomes lower and can even be largely reduced. Furthermore, we examine the growth of the corner roll and the global flow structure based on Fourier mode decomposition, and reveal that the size of the corner roll diminishes as the wavenumber decreases. The reason is that the regions occupied by the cold phase can absorb heat from the hot plumes and thus lower their temperature, which reduces the corner roll's kinetic energy input provided by the buoyancy force, and weakens the feeding process of the corner rolls. This results in the locking of the corner roll into a smaller region near the corner, making it harder for a reversal to occur. Using the concept of horizontal convection caused by non-uniform heating, we find a relevant parameter $k/A$ to describe briefly how the reversal frequency depends on wavenumber and modulation amplitude. The present work provides a new way to control the flow reversals in RB convection through modifying temperature boundary conditions.

The thermal expansion coefficient (CTE) is a vital design parameter for reducing the thermal-stress-induced structural failure of electronic chips/devices. At the micro- and nano-scale, the typical size range of the components in chips/devices, the CTEs are probably different from that of the bulk materials, but an easy and accurate measurement method is still lacking. In this paper, we present a simple but effective method for determining linear CTEs of micro-scale materials only using the prevalent nanoindentation system equipped with a heating stage for precise temperature control. By holding a constant force on the sample surface, while heating the sample at a constant rate, we measure two height–temperature curves at two positions, respectively, which are close to each other but at different heights. The linear CTE is obtained by analyzing the difference of height change during heating. This method can be applied to study the size effect or surface effect of CTE of embedded micro-scale structures, aiding the failure analysis and structural design in the semiconductor industry.

Rosa x odorata (sect. Chinenses, Rosaceae) is an important species distributed only in Yunnan Province, China. There is an abundance of wild variation within the species. Using 22 germplasm resources collected from the wild, as well as R. chinensis var. spontanea, R. chinensis ‘Old Blush’ and R. lucidissima, this study involved morphological variation analysis, inter-trait correlation analysis, principal component analysis and clustering analysis based on 16 morphological traits. This study identified a high degree of morphological diversity in R. x odorata germplasm resources and the variation coefficients had a distribution range from 18.00 to 184.04%. The flower colour had the highest degree of variation, while leaflet length/width had the lowest degree of variation. Inter-trait correlation analysis revealed that there was an extremely significant positive correlation between leaflet length and leaflet width. There was also a significant positive correlation between the number of petals and duration of blooming, and the L* and a* values of flower colour were significantly negatively correlated. Principal component analysis screened five principal components with the highest cumulative contribution rate (81.679%) to population variance. Among the 16 morphological traits, style length, sepal width, flower diameter, flower colour, leaflet length and leaflet width were important indices that influenced the morphology of R. x odorata. This study offers guidance for the further development and utilization of R. x odorata germplasm resources.

Findings of epidemiological studies regarding the association between carrot consumption and lung cancer risk remain inconsistent. The present study aimed to summarise the current epidemiological evidence concerning carrot intake and lung cancer risk with a meta-analysis. We conducted a meta-analysis of case–control and prospective cohort studies, and searched PubMed and Embase databases from their inception to April 2018 without restriction by language. We also reviewed reference lists from included articles. Prospective cohort or case–control studies reporting OR or relative risk with the corresponding 95 % CI of the risk lung cancer for the highest compared with the lowest category of carrot intake. A total of eighteen eligible studies (seventeen case–control studies and one prospective cohort study) were included, involving 202 969 individuals and 5517 patients with lung cancer. The pooled OR of eighteen studies for lung cancer was 0·58 (95 % CI 0·45, 0·74) by comparing the highest category with the lowest category of carrot consumption. Based on subgroup analyses for the types of lung cancer, we pooled that squamous cell carcinoma (OR 0·52, 95 % CI 0·19, 1·45), small-cell carcinoma (OR 0·43, 95 % CI 0·12, 1·59), adenocarcinoma (OR 0·34, 95 % CI 0·15, 0·79), large-cell carcinoma (OR 0·40, 95 % CI 0·10, 1·57), squamous and small-cell carcinoma (OR 0·85, 95 % CI 0·45, 1·62), adenocarcinoma and large-cell carcinoma (OR 0·20, 95 % CI 0·02, 1·70) and mixed types (OR 0·61, 95 % CI 0·46, 0·81). Exclusion of any single study did not materially alter the pooled OR. Integrated epidemiological evidence from observational studies supported the hypothesis that carrot consumption may decrease the risk of lung cancer, especially for adenocarcinoma.

Underground Nuclear Astrophysics in China (JUNA) will take the advantage of the ultra-low background in Jinping underground lab. High current accelerator with an ECR source and detectors were commissioned. JUNA plans to study directly a number of nuclear reactions important to hydrostatic stellar evolution at their relevant stellar energies. At the first period, JUNA aims at the direct measurements of 25Mg(p,γ)26 Al, 19F(p,α) 16 O, 13C(α, n) 16O and 12C(α,γ) 16O near the Gamow window. The current progress of JUNA will be given.

Barium-rich silicates were recently found in the lower Cambrian black shale sequence of Anhui Province, South China. The Ba silicates can be divided into Ba-poor K-feldspar, Ba-rich K-feldspar and cymrite, on the basis of occurrence and composition. The Ba-poor K-feldspar have low BaO contents (<1.00 wt.%) and occur as sporadic grains in mudstone. In contrast, the Ba-rich K-feldspar have higher BaO contents (1.36–20.51 wt.%) and occur mainly as rims around grains of Ba-poor K-feldspar in mudstone, as void fillings in dolostone, and as grains dispersed in chert. The cymrite is observed only in chert and occurs as dispersed euhedral tabular crystals. Analyses of the Ba-poor K-feldspar and Ba-rich K-feldspar provide compositions that total <100 wt.% and show non-stoichiometry characterized by (Na + K + Ba + Ca)apfu less than 1.00 and (Al + Si)apfu slightly higher than 4.00. Raman and infrared (IR) spectroscopy has revealed the presence of ${\rm NH}_{\rm 4}^{\rm +} $ and H2O in the Ba-rich K-feldspar, which accounts for the unusual composition of these feldspars. We suggest that the formation processes of the Ba-poor K-feldspar, Ba-rich K-feldspar and cymrite were closely associated with multi-stage hydrothermal fluids enriched in Ba and NH4, consistent with an extensional tectonic setting during the early Cambrian. The Ba-poor K-feldspars might have formed through interactions between pre-existing K-feldspars and hydrothermal fluids. The Ba-rich K-feldspars in mudstone and dolostone formed mainly by precipitation from hydrothermal fluids that infiltrated the sediments, and we suggest the Ba-rich K-feldspars and cymrite in the chert are of exhalative hydrothermal origin.

Variable stiffness can improve the capability of human–robot interacting. Based on the mechanism of a flexible rack and gear, a rotational joint actuator named vsaFGR is proposed to regulate the joint stiffness. The flexible gear rack can be regarded as a combination of a non-linear elastic element and a linear adjusting mechanism, providing benefits of compactness. The joint stiffness is in the range of 217–3527 N.m/rad, and it is inversely proportional to the 4th-order of the gear displacement, and nearly independent from the joint angular deflection, providing benefits of quick stiffness regulation in a short displacement of 20 mm. The gear displacement with respect to the flexible gear rack is perpendicular to the joint loading force, so the power required for stiffness regulating is as low as 14.4 W, providing benefits of energy saving. The working principles of vsaFGR are elaborated, followed by presentation on the mechanics model and the prototype. The high compactness, great stiffness range and low power cost of vsaFGR are proved by simulations and experiments.

The effect of soil moisture, temperature, and light intensity on the spray deposition of fenoxaprop and imazamethabenz applied to wild oat plants was examined by using fluorescent tracer dye. Based on either biomass or total leaf area, the apparent deposition of the two herbicides diminished in the following order: shading > low temperature ≥ drought ≥ “optimum” > high temperature. The enhanced phytotoxicity of both herbicides under shading could be associated with increased spray deposition; and reduced fenoxaprop phytotoxicity under high temperature stress could be related to reduced deposition. Changes in spray deposition were attributed mainly to differences in herbicide interception due to altered plant morphology. Reduced retention for both herbicides was exhibited only in the plants grown at high temperature. Under “optimum” conditions, fenoxaprop phytotoxicity was directly associated with leaf orientation and thus with the proportion of projected leaf area at the time of herbicide spraying. Given similar application conditions, spray deposition of fenoxaprop and imazamethabenz on wild oat could be estimated by determining the ratio of the projected leaf area, as measured by an image analyzer, to the total leaf area.

Imazamethabenz, an acetohydroxyacid synthase (AHAS)-inhibiting herbicide, was applied at a sublethal rate (200 g ai ha–1) to foliage of greenhouse-grown wild oat plants at the 2-leaf stage without tillers. Main shoot tissues were sampled 1 to 2 wk after imazamethabenz treatment and prepared for light microscopic examination. Histological observations showed that imazamethabenz treatment did not produce drastic changes on leaf structures but did affect chloroplast integrity of fully expanded 2nd leaf and inhibited differentiation of the young 3rd leaf 1 wk after application. The internode length and the number of cells in internodes of the herbicide-treated main stem were greatly reduced, presumably due to the inhibition by imazamethabenz of intercalary meristem cell division in early stages of internode elongation. One week after imazamethabenz application, histochemical studies revealed an increased accumulation of starch granules in chloroplasts of the 2nd leaf but reduced starch levels in the main stem. This confirmed the hypothesis that AHAS inhibitors affected phloem transport of photosynthates.

We consider the nonlinear and ill-posed inverse problem where the Robin coefficient in the Laplace equation is to be estimated using the measured data from the accessible part of the boundary. Two regularisation methods are considered — viz. L2 and H1 regularisation. The regularised problem is transformed to a nonlinear least squares problem; and a suitable regularisation parameter is chosen via the normalised cumulative periodogram (NCP) curve of the residual vector under the assumption of white noise, where information on the noise level is not required. Numerical results show that the proposed method is efficient and competitive.