Despite high altitude was implicated in adverse birth outcomes, there remained a paucity of evidence on low-to-medium altitude effect. This study aimed to explore the association of low-to-medium altitude with birth outcomes. A population-based cross-sectional survey was performed using a stratified multistage random sampling method among women with their infants born during 2010–2013 in Northwestern China. Altitude was determined in meters based on the village or community of the mother’s living areas. Birth outcomes involved birth weight, gestational age, and small for gestational age (SGA). Generalized linear models were fitted to investigate the association of altitude with birth outcomes. Moreover, the dose–response relationship between altitude and birth outcomes was evaluated with a restricted cubic spline function. A total of 27 801 women with their infants were included. After adjusting for potential confounders, every 100-m increase in the altitude was associated with reduced birth weight by 6.4 (95% CI −8.1, −4.6) g, the slight increase of gestational age by 0.015 (95% CI 0.010, 0.020) week, and an increased risk of SGA birth (odds ratio 1.03, 95% CI 1.02, 1.04). Moreover, there was an inversely linear relationship between altitude and birth weight (P for overall < 0.001 and P for nonlinear = 0.312), and a positive linear relationship between altitude and SGA (P for overall < 0.001 and P for nonlinear = 0.194). However, a nonlinear relationship was observed between altitude and gestational age (P for overall < 0.001 and P for nonlinear = 0.010). The present results suggest that low-to-medium altitude is possibly associated with adverse birth outcomes.

From 21 January 2020 to 9 February 2020, three family clusters involving 31 patients with coronavirus disease 2019 were identified in Wenzhou, China. The epidemiological and clinical characteristics of the family cluster patients were analysed and compared with those of 43 contemporaneous sporadic cases. The three index cases transmitted the infection to 28 family members 2–10 days before illness onset. Overall, 28 of the 41 sporadic cases and three of 31 patients in the family clusters came back from Wuhan (65.12 vs. 9.68%, P< 0.001). In terms of epidemiological characters and clinical symptoms, no significant differences were observed between the family cluster and sporadic cases. However, the lymphocyte counts of sporadic cases were significantly lower than those of family cluster cases ((1.32 ± 0.55) × 109/l vs. (1.63 ± 0.70) × 109/l, P = 0.037), and the proportion of hypoalbuminaemia was higher in sporadic cases (18/43, 41.86%) than in the family clusters (6/31, 19.35%) (P < 0.05). Within the family cluster, the second- and third-generation cases had milder clinical manifestations, without severe conditions, compared with the index and first-generation cases, indicating that the virulence gradually decreased following passage through generations within the family clusters. Close surveillance, timely recognition and isolation of the suspected or latent patient is crucial in preventing family cluster infection.

The Wulian complex is located on the northern margin of the Sulu orogenic belt, and was formed by collision between the North China Craton (NCC) to the north and South China Craton (SCC) to the south. It consists of the metasedimentary Wulian Group, gneissic granite and meta-diorite. The U–Pb analyses for the detrital zircons from the Wulian Group exhibit one predominant age population of 2600–2400 Ma with a peak at c. 2.5 Ga and several secondary age populations of > 3000, 3000–2800, 2800–2600, 2200–2000, 1900–1800, 1500–1300 and 1250–950 Ma; some metamorphic zircons have metamorphic ages of c. 2.7, 2.55–2.45, 2.1–2.0 and 1.95–1.80 Ga, which are consistent with magmatic-metamorphic events in the SCC. Additionally, the Wulian Group was intruded by the gneissic granite and meta-diorite at c. 0.76 Ga, attributed to Neoproterozoic syn-rifting bimodal magmatic activity in the SCC and derived from partial melting of Archaean continental crust and depleted mantle, respectively. The Wulian Group therefore has tectonic affinity to the SCC and was mainly sourced from the SCC. The detrital zircons have positive and negative ϵHf(t) values, indicating that their source rocks were derived from reworking of both ancient and juvenile crustal rocks. The major early Precambrian crustal growth took place during c. 3.4–2.5 Ga with a dominant peak at 2.96 Ga and several secondary peaks at 3.27, 2.74 and 2.52 Ga. The two oldest zircons with ages of 3307 and 3347 Ma record the recycling of ancient continental crust (> 3.35 Ga) and crustal growth prior to c. 3.95 Ga in the SCC.

A new, modified version of the cable-suspended Ice and Bedrock Electromechanical Drill (IBED) was designed for drilling in firn, ice, debris-rich ice and rock. The upper part of the drill is almost the same for all drill variants and comprises four sections: cable termination, a slip-ring section, an antitorque system and an electronic pressure chamber. The lower part of the IBED comprises an auger core barrel, reamers, a core barrel for ice/debris-ice drilling and a conventional geological single-tube core barrel or custom-made double-tube core barrel. First, the short and full-scale field versions of the IBED were tested at an outdoor testing stand and a testing facility with a 12.5 m-deep ice well. Then, in the 2018–2019 summer season, the IBED was tested in the field at a site ~12 km south of Zhongshan Station, East Antarctica, and a ~6 cm bedrock core was recovered from a 198 m-deep borehole. A total of 18 d was required to penetrate the ice sheet. The retrieved core samples of blue ice, basal ice and bedrock provided valuable information regarding the Earth's paleo-environment.

Double-layer absorbers have recently been extensively studied because single-layer absorbers can hardly meet the requirements of advanced absorbing materials. However, determining how to couple the matching and absorption layers remains a challenge. In the present work, we applied the hydrothermal method to prepare an ultrasmall Fe3O4 nanoparticle and a hierarchical MXene/Fe3O4 composite and then studied the microwave attenuation capabilities of single- and double-layer absorbers containing these two materials with different thicknesses. Absorbers with well-coupled layers showed improved absorption performance on account of the excellent impedance matching behavior of the Fe3O4 layer and the high microwave attenuation capability of the MXene/Fe3O4 layer. When the thickness of the matching layer filled with Fe3O4 was 0.1 mm and that of the absorption layer filled with MXene/Fe3O4 was 1.9 mm, a maximum reflection loss of −48.7 dB was achieved at 9.9 GHz. More importantly, when the thicknesses of the matching and absorption layers were 0.9 and 1.1 mm, respectively, the effective bandwidth was nearly 3.9 GHz. The double-layer absorbers with enhanced absorption properties may be regarded as a new generation of materials for electromagnetic wave absorption.

Hypertension is a common comorbidity in COVID-19 patients. However, the association of hypertension with the severity and fatality of COVID-19 remain unclear. In the present meta-analysis, relevant studies reported the impacts of hypertension on SARS-CoV-2 infection were identified by searching PubMed, Elsevier Science Direct, Web of Science, Wiley Online Library, Embase and CNKI up to 20 March 2020. As the results shown, 12 publications with 2389 COVID-19 patients (674 severe cases) were included for the analysis of disease severity. The severity rate of COVID-19 in hypertensive patients was much higher than in non-hypertensive cases (37.58% vs 19.73%, pooled OR: 2.27, 95% CI: 1.80–2.86). Moreover, the pooled ORs of COVID-19 severity for hypertension vs. non-hypertension was 2.21 (95% CI: 1.58–3.10) and 2.32 (95% CI: 1.70–3.17) in age <50 years and ⩾50 years patients, respectively. Additionally, six studies with 151 deaths of 2116 COVID-19 cases were included for the analysis of disease fatality. The results showed that hypertensive patients carried a nearly 3.48-fold higher risk of dying from COVID-19 (95% CI: 1.72–7.08). Meanwhile, the pooled ORs of COVID-19 fatality for hypertension vs. non-hypertension was 6.43 (95% CI: 3.40–12.17) and 2.66 (95% CI: 1.27–5.57) in age <50 years and ⩾50 years patients, respectively. Neither considerable heterogeneity nor publication bias was observed in the present analysis. Therefore, our present results provided further evidence that hypertension could significantly increase the risks of severity and fatality of SARS-CoV-2 infection.

This study focuses on the process of the circulation deposition in the Richtmyer–Meshkov instability (RMI). The growth rate of circulation and its sources are theoretically and numerically studied to reveal the physical mechanism of the viscosity in the circulation deposition process. We derive a predicting model of the circulation rate for RMI. More importantly, all the contributing sources are separately predicted. Particularly, the viscous source, which previously lacked theoretical or numerical investigations, is efficiently predicted. The RMI problems in a large range of initial conditions are simulated with the direct simulation Monte Carlo (DSMC) method to verify our predicting model and further reveal the circulation deposition mechanism. The DSMC simulations provide reliable quantification of the circulation deposition (especially viscous contribution) for RMI due to its molecular nature. Our model predicts the circulation rate, baroclinic and viscous sources accurately for all the cases in comparison with the simulations. A new physical insight into the mechanism of viscosity in RMI is provided. Unlike the previous understandings that nearly all circulation deposition in RMI comes from the baroclinic source, this study reveals the hidden positive contribution of the viscous source, especially for high Mach number conditions (up to 11 % of total circulation rate). For RMI, the large viscosity gradient inside the shock waves plays a crucial role in the circulation deposition even under high Reynolds number conditions. Our study also provides exciting opportunities to further understand the viscous contribution to the vorticity dynamics in the reshocked RMI and shock wave–turbulence interactions.

Fluorescent quantum dots (QDs) modified with polyethylene glycol (PEG) and albumin bovine serum (BSA) have profound application in the detection and treatment of hepatocellular carcinoma (HCC) cells. In the present study, the effects and mechanism of PEG and BSA modification on the cytotoxicity of QDs have been explored. It was found that the diameter of the as-prepared QDs, PEG@QDs, BSA@QDs is 3–5 nm, 4–5 nm, and 4–6 nm, respectively. With increase of the treatment time from 0 to 24 h, the HCC cell viability treated with QDs, PEG@QDs, and BSA@QDs obviously decreases, showing a certain time-dependent manner. When the concentration of several nanomaterials is increased from 10 to 90 nM, the cell viability decreases accordingly, exhibiting a certain concentration-dependent manner. Under the same concentration change conditions, the reactive oxygen species contents of cells treated by QDs, PEG@QDs, and BSA@QDs also rise from 7.9 × 103, 6.7 × 103, and 4.7 × 103 to 13.2 × 103, 14.3 × 103, and 12.3 × 103, respectively. In these processes, superoxide dismutase does not play a major role. This study provides strong foundation and useful guidance for QD applications in the diagnosis and treatment of HCC.

Chlamydia trachomatis (CT) infection has been a major public health threat globally. Monitoring and prediction of CT epidemic status and trends are important for programme planning, allocating resources and assessing impact; however, such activities are limited in China. In this study, we aimed to apply a seasonal autoregressive integrated moving average (SARIMA) model to predict the incidence of CT infection in Shenzhen city, China. The monthly incidence of CT between January 2008 and June 2019 in Shenzhen was used to fit and validate the SARIMA model. A seasonal fluctuation and a slightly increasing pattern of a long-term trend were revealed in the time series of CT incidence. The monthly CT incidence ranged from 4.80/100 000 to 21.56/100 000. The mean absolute percentage error value of the optimal model was 8.08%. The SARIMA model could be applied to effectively predict the short-term CT incidence in Shenzhen and provide support for the development of interventions for disease control and prevention.

B vitamins (including folate, vitamin B2, vitamin B6 and vitamin B12) and methionine are essential for methylation reactions, nucleotide synthesis, DNA stability and DNA repair. However, epidemiological evidence among Chinese populations is limited. The objective of this study was to evaluate B vitamins and methionine in relation to colorectal cancer risk in a Chinese population. A case–control study was conducted from July 2010 to April 2019. A total of 2502 patients with colorectal cancer were recruited along with 2538 age- (5-year interval) and sex-matched controls. Dietary data were collected using a validated FFQ. Multivariable logistic regression was used to assess OR and 95 % CI. The intake of folate, vitamin B2, vitamin B6 and vitamin B12 was inversely associated with colorectal cancer risk. The multivariable OR for the highest quartile v. the lowest quartile were 0·62 (95 % CI 0·51, 0·74; Ptrend < 0·001) for folate, 0·46 (95 % CI 0·38, 0·55; Ptrend < 0·001) for vitamin B2, 0·55 (95 % CI 0·46, 0·76; Ptrend < 0·001) for vitamin B6 and 0·72 (95 % CI 0·60, 0·86; Ptrend < 0·001) for vitamin B12. No statistically significant association was found between methionine intake and colorectal cancer risk. Stratified analysis by sex showed that the inverse associations between vitamin B12 and methionine intake and colorectal cancer risk were found only among women. This study indicated that higher intake of folate, vitamin B2, vitamin B6 and vitamin B12 was associated with decreased risk of colorectal cancer in a Chinese population.

This study presents monazite and rutile U–Pb and hornblende and biotite 40Ar/39Ar geochronological data for high-grade rocks of the eastern Grenville-aged Rayner orogen at Mount Brown in order to analyse the extent and degree of Pan-African-aged reworking. Monazite from paragneiss yields U–Pb ages of 910 Ma for larger granular grains and 670–630 Ma for smaller globular beads around garnet porphyroblasts or hosted by symplectites. Rutile from leucogneiss yields U–Pb ages of 520–515 Ma. Hornblende and biotite from different rock types yield 40Ar/39Ar plateau ages of 744 and 520–505 Ma, respectively. Combining these results with published zircon U–Pb age data suggests that granulite facies metamorphism occurred at 910 Ma, with a local low-temperature fluid flow event at 670–630 Ma and thermal reworking at 520–505 Ma. The older age of 744 Ma may reflect cooling or partial resetting of the hornblende 40Ar/39Ar system, indicating that Pan-African-aged reworking did not exceed temperatures much higher than the hornblende Ar closure temperature. These data also suggest that the complete isotopic resetting of some minerals may occur without the growth of new mineral phases, providing an example of the style of reworking that is likely to occur in polymetamorphic terranes.

A novel wall-climbing robot with multiple attachment modes is proposed. For uneven surfaces, the mechanical model of a spine wheel is brought out to grab the surfaces with its multi-spines. For smooth surfaces, an adhesive belt is obtained by the industrial synchronous belt and the polyurethane material to adhere to the surfaces. To avoid the robot overturning, an adsorption device with flexible skirt edge is presented. In addition, the normal force and motor torque are evaluated respectively. Finally, the prototype of the wall-climbing robot is manufactured and tested, and the experimental results show that the robot could climb the wall surface 0–360° with a maximum load of 0.5 kg.

Loyalty is a permanent concern to dictators. It is unclear, however, whether loyalty to a dictator assures the ruling group's cohesiveness. This study shows that authoritarian political elites under promotion pressure, while remaining loyal to their superior, also compete within factions to outrival their peers. Exploiting data on Chinese provincial leaders and local media reports on corruption investigations and industrial accidents (2000–2014), we find that Chinese elites promote negative news related to their co-faction peers as frequently as - or, depending on the measure, even more often than - they promote similar news regarding members of other factions. We also find that negative reports indeed reduce the promotion probability of reported cadres, while increasing that of reporting ones.

We conducted a survey of 16,914 patients to determine the point prevalence of healthcare-associated catheter-associated urinary tract infection (HA-CAUTI) and urinary catheter care in public hospitals in Hong Kong. Overall HA-CAUTI prevalence was 0.27%. Compliance was generally good, except for documenting the date of planned removal and securing the catheter properly.