Soil mercury spatial variations in the fault zone and corresponding influence factors

Field measurements were performed using a LUMEX RA-915+ mercury vapour analyser to determine the gaseous mercury (Hg) concentrations in the soils of the North China plain, Loess Plateau, Changping District, Haiyuan fault zone, and north Beiluntai (BLT) fault at the edge of south Tianshan. The factors affecting the soil gas Hg concentration, such as the sampler type, test hole depth, soil characteristics, fault characteristics, and the mechanisms of their influence are discussed in terms of a gas diffusion equation. The results show that (1) the soil gas Hg concentration is affected mainly by the time lapse between the hole drilling and measurement, test hole depth and sampler shape; (2) the measured soil gas Hg concentration agrees well with the gas diffusion equation analytical solution, and the curve shape is closely related to the degree of Hg enrichment in the soil and the soil density; and (3) the soil gas concentration in the fracture zone is largely affected by the rock type, tectonics, the fault slip rate, the degree of fault locking, the development degree of fractures between the hanging wall and footwall, and the degree of fracture locking because these factors can alter the Hg upward transport channels and degree of surface enrichment. The effects of these factors on the diffusion coefficient in shallow soil layers are insignificant. The diffusion coefficient D depends on the particle size, density and porosity of the soil materials

Bifurcation of pressurized functionally graded elastomeric hollow cylinders

Various bifurcation behaviors, including asymmetric axial buckling induced by end thrust, bifurcation under external pressure, and eversion without any loading, of a soft circular hollow cylinder (or cylindrical shell) composed of functionally graded incompressible elastomeric material are considered in a unified way. Based on the nonlinear elasticity theory of a deformable continuous body undergoing large deformation and the linearized incremental theory for a superimposed infinitesimal deformation, an efficient approach for buckling analysis is developed and applied to the cylinder subjected to a combination of axial end thrust and internal/external pressure. It is based on the state-space formalism, which naturally avoids the derivatives of instantaneous material constants, enabling a convenient and accurate numerical implementation. Along with the layerwise method, an analytical characteristic equation (i.e. the bifurcation criterion) governing the general asymmetric buckling of the cylinder is derived. Detailed parametric studies are then carried out for a pressurized soft functionally graded hollow cylinder using an incompressible Mooney-Rivlin material model. The effects of material gradient on bifurcation induced either by end thrust or external pressure are discussed through numerical examples. Not only does this study provide an efficient tool for buckling analysis of soft cylinders, some findings that are unique to a functionally graded material are also highlighted. All in all, it is found highly possible to tune the bifurcation behavior of soft elastomeric cylindrical shells by tailoring material composition and/or adjusting the pressures acting on the surfaces of the cylinder

Three-dimensional buckling and free vibration analyses of initially stressed functionally graded graphene reinforced composite cylindrical shell

The buckling and free vibration of initially stressed functionally graded cylindrical shell reinforced with non-uniformly distributed graphene platelets (GPLs) are investigated using the state-space formulation based on three-dimensional elasticity theory. The shell is under an axial initial stress and composed of multilayers with GPLs uniformly dispersed in each individual layer but its weight fraction changing layer-by-layer along the thickness direction. The modified Halpin-Tsai model and rule of mixtures are employed to evaluate the effective elastic properties of the GPL-reinforced shell. Analytical buckling and frequency solutions are obtained for simply supported shells. Numerical results are presented for functionally graded GPL-reinforced cylindrical shells with five GPL dispersion patterns (GPL-UD, GPL-V, GPL-A, GPL-X, and GPL-O). The effects of GPL weight fraction, dispersion pattern, geometry, and size as well as the influence of initial stress on the buckling and free vibration characteristics of the shell are discussed in detail. It is found that the addition of a small amount of GPLs significantly increases the critical buckling stress and natural frequencies. The GPL-X pattern outperforms other patterns for thin composite shells while the uniform pattern GPL-UD works better for thick composite shells

Review of Associations between Built Environment Characteristics and Severe Acute Respiratory Syndrome Coronavirus 2 Infection Risk.

The coronavirus disease 2019 pandemic has stimulated intensive research interest in its transmission pathways and infection factors, e.g., socioeconomic and demographic characteristics, climatology, baseline health conditions or pre-existing diseases, and government policies. Meanwhile, some empirical studies suggested that built environment attributes may be associated with the transmission mechanism and infection risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, no review has been conducted to explore the effect of built environment characteristics on the infection risk. This research gap prevents government officials and urban planners from creating effective urban design guidelines to contain SARS-CoV-2 infections and face future pandemic challenges. This review summarizes evidence from 25 empirical studies and provides an overview of the effect of built environment on SARS-CoV-2 infection risk. Virus infection risk was positively associated with the density of commercial facilities, roads, and schools and with public transit accessibility, whereas it was negatively associated with the availability of green spaces. This review recommends several directions for future studies, namely using longitudinal research design and individual-level data, considering multilevel factors and extending to diversified geographic areas

Wetting and deposition characteristics of air-assisted spray droplet on large broad-leaved crop canopy

Precision and efficient pesticide spraying is an important part of precision agriculture, banana is a large broad-leaved plant, with pests and diseases, has a high demand for spraying and pest control. The purpose of this study was to clarify the wettability of different pesticides on the banana leaf surface, and the effects of nozzle type and working parameters on the deposition distribution performance under air-assisted spray conditions. The wettability test results of different pesticides on banana leaf surfaces showed that the wettability of the adaxial side was always stronger than that of the abaxial side, the smaller the surface tension of the droplets, the better the wettability on the surface. The spray experiment was carried out on the previously developed air-assisted sprayer with the latest developed intelligent variable spray control system. Three types of nozzles were used to spray with different combinations of working parameters. The deposition distribution performance on the banana leaf surface was obtained by image processing using a self-compiled program. The experimental results show that the nozzle type, wind speed, and spray pressure have significant effects on the deposition distribution performance. Through the study of the interaction and coupling effect of nozzle type and working parameters on the spray droplet deposition distribution on both sides of banana leaves, the results show that under the conditions of hollow cone nozzle, 0.5Mpa spray pressure and 3-5 m/s wind speed, the spray coverage and droplet density are in the optimal state. This is mainly due to the low spray pressure and/or wind speed is not enough to make the banana leaves vibrate and improve the performance of pesticide deposition. excessive spray pressure and/or wind speed will cause large deformation of banana leaves and make them airfoil stable, which reduces the surface deposition performance. It is of great significance for promoting sustainable and intelligent phytoprotection

AANAT transgenic sheep generated via OPS vitrified-microinjected pronuclear embryos and reproduction efficiency of the transgenic offspring

Background The open pulled straw (OPS) vitrification method has been successfully applied in mouse, pig, and goat embryos as well as in buffalo oocytes, but it has not yet been applied to the microinjected embryos. This study examined the effects of OPS vitrification on embryo development and the reproductive capacity of the transgenic offspring in order to establish a method for preservation of microinjected embryos. Methods Ovine pronuclear embryos were microinjected with the exogenous aralkylamine N-acetyltransferase gene (AANAT), frozen by the OPS method, and subsequently thawed for embryo transplantation. Pregnancy rate, lambing rate, survival rate, average birth weight and transgenic positive rate as well as reproduction efficiency and hormone level of the transgenic offspring were investigated to analyze the effect of OPS vitrification on microinjectd pronuclear embryos. Results No significant differences were observed in the birth rate, lamb survival rate and transgenic positive rate between the frozen and non-frozen AANAT-microinjected pronuclear embryos. The average birth weight of the frozen embryos offspring was greater than that of the non-frozen embryos. Importantly, the transgenic offspring that overexpressed the AANAT gene showed improved ovulation efficiency and lambing rate by regulating their hormone levels. Conclusions The OPS vitrification approach may be a valuable method in microinjected- embryo transfer technology, which could reserve embryos and result in fewer unnecessary animal sacrifices. In addition, the AANAT+ transgenic offspring exhibited improved reproductive capacity on account of regulation effect of melatonin on reproductive hormone. These data may provide available references for human-assisted reproduction

Associations between maternal complications during pregnancy and childhood asthma: a retrospective cohort study

© 2023 The Authors. Published by the European Respiratory Society. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://openres.ersjournals.com/content/9/2/00548-2022Background Studies on the associations between maternal complications during pregnancy and childhood asthma are exclusively conducted in Western countries. The findings are mixed and may not be translated to other populations. We aimed to investigate the associations among the Chinese population and to determine whether the associations were mediated through pre-term birth, caesarean delivery, low birthweight and not breastfeeding in the first 6 months. Methods We conducted a retrospective cohort study of 166 772 children in Guangzhou, China. Information on maternal gestational hypertension, gestational diabetes and gestational anaemia during pregnancy was extracted from medical records. Ever-diagnosis of asthma in children aged 6–12 years was obtained by questionnaire. Logistic regression models and mediation analyses were used to estimate the adjusted odds ratios (aORs) and 95% confidence intervals for childhood asthma. Results Gestational hypertension, gestational diabetes and gestational anaemia during pregnancy were associated with an increased risk of ever-diagnosed childhood asthma: aOR 1.48 (95% CI 1.37–1.60), 1.71 (95% CI 1.65–1.78) and 1.34 (95% CI 1.26–1.45), respectively. A stronger association was observed for two or three gestational complications (aOR 2.02 (95% CI 1.93–2.16)) than one gestational complication (aOR 1.64 (95% CI 1.52–1.77)). The aOR for the three gestational complications was 1.35 (95% CI 1.26–1.45), 1.63 (95% CI 1.58–1.70) and 1.32 (95% CI 1.24–1.43), respectively, after controlling for the mediators, including pre-term birth, caesarean delivery, low birthweight and not breastfeeding in the first 6 months. Conclusions Gestational hypertension, gestational diabetes and gestational anaemia were associated with childhood asthma, and the associations were partially explained by the mediation effects.This study was supported by National Natural Science Foundation of China (82073571 and 81773457 to J. Tang).Published versio

Purification and Characterization of Two New Allergens from the Venom of Vespa magnifica

Due to poor diagnostic facilities and a lack of medical alertness, allergy to Vespa wasps may be underestimated. Few allergens have been identified from Vespa wasps