The safety of human-collaborative operations with robots depends on monitoring the external torque of the robot, in which there are toque sensor-based and torque sensor-free methods. Economically, the classic method for estimating joint external torque is the first-order momentum observer (MOB) based on a physic model without torque sensors. However, uncertainties in the dynamic model, which encompasses parameters identification error and joint friction, affect the torque estimation accuracy. To address this issue, this paper proposes using the backpropagation neural network (BPNN) method to estimate joint external torque without the delicate physical model by utilizing the powerful machine learning ability to handle the uncertainties of the MOB method and improve the accuracy of torque estimation. Using data obtained from the torque sensor to train the BPNN to build up a digital torque model, the trained BPNN can perceive force in practical applications without relying on the torque sensor. In the end, by contrast to the classic first-order MOB, the result demonstrates that BPNN achieves higher estimation accuracy compared to the MOB.

Paranosema locustae is an environmentally friendly parasitic predator with promising applications in locust control. In this study, transcriptome sequencing was conducted on gonadal tissues of Locusta migratoria males and females infected and uninfected with P. locustae at different developmental stages. A total of 18,635 differentially expressed genes (DEGs) were identified in female ovary tissue transcriptomes, with the highest number of DEGs observed at 1 day post-eclosion (7141). In male testis tissue transcriptomes, a total of 32,954 DEGs were identified, with the highest number observed at 9 days post-eclosion (11,245). Venn analysis revealed 25 common DEGs among female groups and 205 common DEGs among male groups. Gene ontology and Kyoto Encyclopaedia of Genes and Genome analyses indicated that DEGs were mainly enriched in basic metabolism such as amino acid metabolism, carbohydrate metabolism, lipid metabolism, and immune response processes. Protein–protein interaction analysis results indicated that L. migratoria regulates the expression of immune- and reproductive-related genes to meet the body's demands in different developmental stages after P. locustae infection. Immune- and reproductive-related genes in L. migratoria gonadal tissue were screened based on database annotation information and relevant literature. Genes such as Tsf, Hex1, Apolp-III, Serpin, Defense, Hsp70, Hsp90, JHBP, JHE, JHEH1, JHAMT, and VgR play important roles in the balance between immune response and reproduction in gonadal tissues. For transcriptome validation, Tsf, Hex1, and ApoLp-III were selected and verified by quantitative real-time polymerase chain reaction (qRT-PCR). Correlation analysis revealed that the qRT-PCR expression patterns were consistent with the RNA-Seq results. These findings contribute to further understanding the interaction mechanisms between locusts and P. locustae.

In this study, the excretory–secretory products (ESP) of the daughter sporocysts of Vesicocoelium solenophagum (Trematoda) and plasma proteins of its host, Sinonovacula constricta were characterized by sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS–PAGE) and gelatin-substrate gel analyses, and the relationships between them were analysed using immunoblotting. Proteinase activity was detected in the ESP from daughter sporocysts of V. solenophagum. Some polypeptides of the ESP were found to be recognized by antiserum, raised against plasma from non-infected S. constricta, suggesting that the ESP may mimic host molecules (molecular mimicry). In contrast, neither the obvious proteinase activity nor the binding to the antisera was observed for the soluble proteins of daughter sporocyst, indicating that the ESP may play a important role in the parasite–host relationship. Although the plasma of infected S. constricta contained polypeptides that were similar to the plasma of non-infected bivalves, increased quantities of proteins at >170 kDa, 15 kDa and decreased quantities at 60 kDa were observed in the plasma of infected bivalves. Immunoblotting analysis revealed that the plasma of infected bivalves had a faint reaction with both anti-non-infected plasma antisera and anti-sporocyst antisera. These results indicated that the structure and quantity of some polypeptides from the plasma of infected bivalves had changed because of the infection with V. solenophagum. The polypeptides between the plasma of bivalves from a non-epidemic area and that from an epidemic area were similar, but the former had more polypeptides of 170–220 kDa and much greater proteinase activity than the latter, suggesting that the increased polypeptides of 170–220 kDa and the high proteinase activity in plasma may be favourable for protecting the host from being invaded by the parasites.

In this study, a toroidal quartz ($20\overline{2}3$) crystal is designed for monochromatic X-ray imaging at 72.3°. The designed crystal produces excellent images of a laser-produced plasma emitting He-like Ti X-rays at 4.75 keV. Based on the simulations, the imaging resolutions of the spherical and toroidal crystals in the sagittal direction are found to be 15 and 5 μm, respectively. Moreover, the simulation results show that a higher resolution image of the source can be obtained by using a toroidal crystal. An X-ray backlight imaging experiment is conducted using 4.75 keV He-like Ti X-rays, a 3 × 3 metal grid, an imaging plate and a toroidal quartz crystal with a lattice constant of 2d = 0.2749 nm. The meridional and sagittal radii of the toroidal α-quartz crystal are 295.6 and 268.5 mm, respectively. A highly resolved image of the microgrid, with a spatial resolution of 10 μm, is obtained in the experiment. By using similar toroidal crystal designs, the application of a spatially resolved spectrometer with high-resolution X-ray imaging ability is capable of providing imaging data with the same magnification ratio in the sagittal and meridional planes.

Thermal convection of fluid is a more efficient way than diffusion to carry heat from hot sources to cold places. Here, we experimentally study the Rayleigh–Bénard convection of aqueous glycerol solution in a cubic cell with suspensions of rod-like particles made of polydimethylsiloxane. The particles are inertial due to their large thermal expansion coefficient and finite sizes. The thermal expansion coefficient of the particles is three times larger than that of the background fluid. This contrast makes the suspended particles lighter than the local fluid in hot regions and heavier in cold regions. The heat transport is enhanced at relatively large Rayleigh number ($\textit {Ra}$) but reduced at small $\textit {Ra}$. We demonstrate that the increase of Nusselt number arises from the particle–boundary layer interactions: the particles act as ‘active’ mixers of the flow and temperature fields across the boundary layers.

Polycarboxylate superplasticizer (PCE) is sensitive to the clay present in concrete aggregates. In particular, Montmorillonite (Mnt), an impurity inevitably contained in the aggregate, can significantly influence the performance of concrete. In an effort to improve the compatibility of PCE, a zwitterionic PCE with cationic amide groups and shorter side-chain lengths was synthesized via free radical copolymerization. The optimal synthesis condition was verified via Box-Behnken design. In addition to characterizing the PCE, the performance of PCE in cement pastes with or without Na-Mnt was examined and the underlying mechanism was explored. The results show that, compared with commercially available PCE, the required dosage of PCE for cements containing Na-Mnt decreased. Unlike commercially available PCE, no intercalation occured on the newly manufactured clay-tolerant PCE within the layers of Mnt, resulting in a greater sorption thickness and improved dispersion of the cements containing Na-Mnt.

The mortality of coronavirus disease 2019 (COVID-19) differs between countries and regions. This study aimed to clarify the clinical characteristics of imported and second-generation cases in Shaanxi. This study included 134 COVID-19 cases in Shaanxi outside Wuhan. Clinical data were compared between severe and non-severe cases. We further profiled the dynamic laboratory findings of some patients. In total, 34.3% of the 134 patients were severe cases, 11.2% had complications. As of 7 March 2020, 91.8% patients were discharged and one patient (0.7%) died. Age, lymphocyte count, C-reactive protein, erythrocyte sedimentation rate, direct bilirubin, lactate dehydrogenase and hydroxybutyrate dehydrogenase showed difference between severe and no-severe cases (all P < 0.05). Baseline lymphocyte count was higher in survived patients than in non-survivor case, and it increased as the condition improved, but declined sharply when death occurred. The interleukin-6 (IL-6) level displayed a downtrend in survivors, but rose very high in the death case. Pulmonary fibrosis was found on later chest computed tomography images in 51.5% of the pneumonia cases. Imported and second-generation cases outside Wuhan had a better prognosis than initial cases in Wuhan. Lymphocyte count and IL-6 level could be used for evaluating prognosis. Pulmonary fibrosis as the sequelae of COVID-19 should be taken into account.

The influence of the nozzle aspect ratio ($AR=1$, 2 and 4), stroke length ($L_{0}=1.85$, 3.7 and 5.55) and Reynolds number ($Re=79$, 158, 316 and 632) on the behaviour of elliptic synthetic jets is studied experimentally. Laser-induced fluorescence and two-dimensional and stereoscopic particle image velocimetry are used to analyse the vortex dynamics and evolution mechanism. It is found that the fluid elements around the major axis of an elliptic vortex ring move downstream faster and tend to approach the centreline, while the fluid elements around the minor axis move downstream at a slower speed and away from the centreline, thereby resulting in the occurrence of the well-known axis-switching phenomenon for elliptic synthetic jets. During this process, a pair of arc-like vortices forms ahead of the primary vortex ring, and they are constituted by streamwise vortices in the leg part and spanwise vortices in the head part; two pairs of streamwise vortices form from the inside of the primary vortex ring and develop in the tails. The streamwise vortices are pushed away progressively from the centreline by the synthetic jet vortex rings that are formed during the subsequent periods. These additional vortical structures for non-circular synthetic jets show regular and periodic characteristics, which are quite different from the previous findings for non-circular jets. Their mutual interaction with the vortex ring causes significant changes in the topology of elliptic synthetic jets, which further results in the variation of the statistical characteristics. Increasing the aspect ratio, stroke length and Reynolds number will make the evolution of the synthetic jet become more unstable and complex. In addition, the entrainment rate of an elliptical synthetic jet is larger than that of a circular synthetic jet and it increases with the nozzle aspect ratio ($AR\leqslant 4$) and Reynolds number. It is indicated that the formation of streamwise vortices could enhance the entrainment rate. This finding provides substantial evidence for the potential application of elliptic synthetic jets for effective flow control.

Leucine plays an important role in promoting muscle protein synthesis and muscle remodelling. However, what percentage of leucine is appropriate in creep feed and what proteome profile alterations are caused by dietary leucine in the skeletal muscle of piglets remain elusive. In this case, we applied isobaric tags for relative and absolute quantitation to analyse the proteome profile of the longissimus dorsi muscles of weanling piglets fed a normal leucine diet (NL; 1·66 % leucine) and a high-leucine diet (HL; 2·1 % leucine). We identified 157 differentially expressed proteins between these two groups. Bioinformatics analysis of these proteins exhibited the suppression of oxidative phosphorylation and fatty acid β-oxidation, as well as the activation of glycolysis, in the HL group. For further confirmation, we identified that SDHB, ATP5F1, ACADM and HADHB were significantly down-regulated (P<0·01, except ATP5F1, P<0·05), whereas the glycolytic enzyme pyruvate kinase was significantly up-regulated (P<0·05) in the HL group. We also show that enhanced muscle protein synthesis and the transition from slow-to-fast fibres are altered by leucine. Together, these results indicate that leucine may alter energy metabolism and promote slow-to-fast transitions in the skeletal muscle of weanling piglets.

In this paper, the recent studies of laboratory astrophysics with strong magnetic fields in China have been reviewed. On the Shenguang-II laser facility of the National Laboratory on High-Power Lasers and Physics, a laser-driven strong magnetic field up to 200 T has been achieved. The experiment was performed to model the interaction of solar wind with dayside magnetosphere. Also the low beta plasma magnetic reconnection (MR) has been studied. Theoretically, the model has been developed to deal with the atomic structures and processes in strong magnetic field. Also the study of shock wave generation in the magnetized counter-streaming plasmas is introduced.

Little is known about the status of the snow leopard Panthera uncia in Qomolangma National Nature Reserve, located on the northern aspect of Mount Everest in Tibet. To address this, during May–September 2014 we conducted line transects, camera trapping, household interviews, and socioeconomic statistics analysis. We surveyed 14 transects and located 287 putative snow leopard signs, with a mean density of 1.9 sign sites km–1, 3.8 signs km–1, and 1.4 scrapes km–1. We set 41 camera traps and recorded a minimum of seven individual snow leopards. Our results were comparable to snow leopard abundance estimates for neighbouring protected areas in Nepal. Semi-structured interviews with 46 (59%) households found that local people were generally supportive of snow leopard conservation, for a variety of economic, legislative, and religious reasons. The socio-economic situation in the Reserve underwent dramatic changes between 2000 and 2014. The human population increased by 28.9%, the livestock population decreased by 9.9%, the number of tourists in 2014 was 6.8 times greater than in 2005, and the local gross domestic product underwent an annual increase of 15%. We discuss the current threats to snow leopards, and recommend that more rigorous, comprehensive, and interdisciplinary research be undertaken to provide an evidential basis for the formulation of effective conservation policies and programmes.

Analyses of morphological, anatomical, chemical and DNA sequences led to the recognition of ten species of Anzia in the Hengduan Mountains, which harbour all species known from China, including A. pseudocolpota sp. nov. and A. hypomelaena comb. & stat. nov. Furthermore, populations similar to A. hypoleucoides but with narrow lobes and a yellow-orange pigmented medulla may be a phylogenetically distinct species tentatively recognized as A. aff. hypoleucoides. The species are primarily distinguished by the presence or absence of a central axis, the colour and shape of the spongy cushion and the nature of the secondary compounds. A key to all known species of Anzia from China is presented.