Product miniaturization is an emerging trend for facilitating product usage, enabling unique product functions to be implemented in micro-scaled geometries and features, and further reducing product ...weight and volume. Recently, a demand for microparts increased significantly in many industry clusters. Development of the advanced micromanufacturing technologies for fabrication of such microparts has thus become a critical issue. Microforming, which offers attractive characteristics including high productivity, low cost and good quality of the formed parts, provides a promising approach to fabricating metallic microparts. In the last two decades, a lot of effort has been made to the researches on size effect related deformation behaviors in microforming process and the development of the process. Having a panorama of these researches is necessary to support micropart design and development via microforming, and further advance this micromanufacturing process. In this paper, an intensive review on the latest development of microforming technologies is presented. First of all, the paper is focused on the review of the size effect-affected deformation behaviors and the mechanisms of the changes of flow stress, flow behavior, fracture behavior, elastic recovery, tooling–workpiece interfacial friction and the surface finish of the formed parts. The state-of-the-art microforming processes, including micro deep drawing, microembossing, micropunching, microcoining, microextrusion, microheading, and micro progressive forming are then presented. Finally, some research issues from the implementation of mass production perspective are also discussed.
The development of active, cost-effective and stable oxygen-evolving catalysts is one of the major challenges for solar-to-fuel conversion towards sustainable energy generation. Iridium oxide ...exhibits the best available compromise between catalytic activity and stability in acid media, but it is prohibitively expensive for large-scale applications. Therefore, preparing oxygen-evolving catalysts with lower amounts of the scarce but active and stable iridium is an attractive avenue to overcome this economical constraint. Here we report on a class of oxygen-evolving catalysts based on iridium double perovskites which contain 32 wt% less iridium than IrO2 and yet exhibit a more than threefold higher activity in acid media. According to recently suggested benchmarking criteria, the iridium double perovskites are the most active catalysts for oxygen evolution in acid media reported until now, to the best of our knowledge, and exhibit similar stability to IrO2.
China presently contributes the largest amount of anthropogenic mercury (Hg) emission into the atmosphere in the world. Over the past decade, numerous studies have been conducted to characterize the ...concentration and forms of atmospheric Hg in China, which provide insights into the spatial and temporal distributions of atmospheric Hg through ground-based measurements at widely diverse geographical locations and during cruise and flight campaigns. In this paper, we present a comprehensive review of the state of understanding in atmospheric Hg in China. Gaseous elemental mercury (GEM) and particulate-bound mercury (PBM) measured at the remote sites in China are substantially elevated compared to the background values in the Northern Hemisphere. In Chinese urban areas, the highly elevated GEM, PBM and gaseous oxidized mercury (GOM) were mainly derived from local anthropogenic Hg emissions, whereas regional anthropogenic emissions and long-range transport from domestic source regions are the primary causes of the elevated GEM and PBM concentrations at remote sites. Using 7-9 years of continuous observations at a remote site and an urban site, a slight increase in atmospheric GEM (2.4-2.5 % yr-1) was identified (paired samples test: p < 0.01), which is in agreement with the increasing domestic anthropogenic emissions. Anthropogenic GEM emission quantity in China estimated through the observed GEM / CO concentration ratios ranged from 632 to 1138 t annually over the past decade, 2-3 times larger than published values using emission activity data. Modeling results and filed measurements show dry deposition is the predominant process for removing Hg from the atmosphere, 2.5-9.0 times larger than wet deposition, due to the elevated atmospheric GEM and PBM concentrations that facilitate dry deposition to terrestrial landscapes. Further studies to reconcile the observed and simulated Hg concentrations, to understand the impact of domestic emission reduction on Hg concentration and deposition and to delineate the role of Hg emission and deposition of China in the global Hg biogeochemical cycle, are needed.
The electron butterfly distribution, characterized by pitch angles (PA) primarily at 45° and 135°, was rarely observed in Earth's magnetotail. Here using the high‐resolution measurements from ...Magnetospheric Multiscale mission, we present the observation of electron butterfly distribution in a contracting dipolarization front (DF), and propose a new physical mechanism to explain its formation. Specifically, we discover that the electron butterfly distribution only exhibited in the locally contracted DF and was observed above 1.7 keV. We infer that local contraction of the DF transformed its configuration from a magnetic bottle to an hourglass‐shaped magnetic structure, and the butterfly distribution was formed by the magnetic mirror effect of this magnetic hourglass. Additionally, the theoretically estimated loss cone of the magnetic hourglass fits well with the observations of electrons, validating our inference about the formation mechanism. These findings can improve our understanding of electron dynamics in Earth's magnetosphere.
Plain Language Summary
Examining the pitch‐angle (PA) distribution of electrons can help us understand the electron dynamic process in space. In this paper, we present the observation of electron butterfly distribution, characterized by PA primarily around 45° and 135°, in Earth's magnetotail. We find that the electron butterfly distribution was observed only above 1.7 keV, and exhibited in a locally contracting dipolarization front (DF). We propose a new formation mechanism for this distribution, and perform the theoretical calculations to validate it. Our findings can significantly improve the knowledge of electron dynamics in Earth's magnetosphere.
Key Points
The electron butterfly distribution was observed above 1.7 keV and only exhibited in the contracted dipolarization front (DF)
The local contraction of the DF transformed its configuration from a magnetic bottle to an hourglass‐shaped magnetic structure
The butterfly distribution is formed by the magnetic mirror effect of the hourglass‐shaped structure
Despite the great progress in the treatment of colorectal cancer (CRC), the current standard treatment protocols still have many limitations, and there is an urgent need for more effective biomarkers ...for personalized patient treatment. Circulating tumor DNA (ctDNA), as a dynamic, non-invasive liquid biopsy approach, overcomes the limitations of tissue biopsy in detecting tumor heterogeneity and molecular evolution. Current evidence from several studies suggests that ctDNA shows great promise in stratifying recurrence risk, guiding treatment decisions, and monitoring early recurrence. In addition, ctDNA can improve the efficiency of clinical research and drug development. However, the lack of standardisation of pre-ctDNA test variables and analysis procedures and the high technical costs limit its promotion and development. In this review, we summarize the available evidence on ctDNA in the clinical management of CRC and present its limitations and strategies for improvement.
Spatial pattern information of carbon density in forest ecosystem including forest litter carbon (FLC) plays an important role in evaluating carbon sequestration potentials. The spatial variation of ...FLC density in the typical subtropical forests in southeastern China was investigated using Moran's I, geostatistics and a geographical information system (GIS). A total of 839 forest litter samples were collected based on a 12 km (south–north) × 6 km (east–west) grid system in Zhejiang province. Forest litter carbon density values were very variable, ranging from 10.2 kg ha−1 to 8841.3 kg ha−1, with an average of 1786.7 kg ha−1. The aboveground biomass had the strongest positive correlation with FLC density, followed by forest age and elevation. Global Moran's I revealed that FLC density had significant positive spatial autocorrelation. Clear spatial patterns were observed using local Moran's I. A spherical model was chosen to fit the experimental semivariogram. The moderate "nugget-to-sill" (0.536) value revealed that both natural and anthropogenic factors played a key role in spatial heterogeneity of FLC density. High FLC density values were mainly distributed in northwestern and western part of Zhejiang province, which were related to adopting long-term policy of forest conservation in these areas, while Hang-Jia-Hu (HJH) Plain, Jin-Qu (JQ) Basin and coastal areas had low FLC density due to low forest coverage and intensive management of economic forests. These spatial patterns were in line with the spatial-cluster map described by local Moran's I. Therefore, Moran's I, combined with geostatistics and GIS, could be used to study spatial patterns of environmental variables related to forest ecosystem.
Summary
Recent studies found that hepatitis C virus (HCV) may invade the central nervous system, and both HCV and Parkinson's disease (PD) have in common the overexpression of inflammatory ...biomarkers. We analysed data from a community‐based integrated screening programme based on a total of 62 276 subjects. We used logistic regression models to investigate association between HCV infection and PD. The neurotoxicity of HCV was evaluated in the midbrain neuron–glia coculture system in rats. The cytokine/chemokine array was performed to measure the differences of amounts of cytokines released from midbrain in the presence and absence of HCV. The crude odds ratios (ORs) for having PD were 0.62 95% confidence interval (CI), 0.48–0.81 and 1.91 (95% CI, 1.48–2.47) for hepatitis B virus (HBV) and HCV. After controlling for potential confounders, the association between HCV and PD remained statistically significant (adjusted OR = 1.39; 95% CI, 1.07–1.80), but not significantly different between HBV and PD. The HCV induced 60% dopaminergic neuron death in the midbrain neuron–glia coculture system in rats, similar to that of 1‐methyl‐4‐phenylpyridinium (MPP+) but not caused by HBV. This link was further supported by the finding that HCV infection may release the inflammatory cytokines, which may play a role in the pathogenesis of PD. In conclusion, our study demonstrated a significantly positive epidemiological association between HCV infection and PD and corroborated the dopaminergic toxicity of HCV similar to that of MPP+.
Calls have been made for water and ecological planning and design to tackle the ongoing environmental degradation, yet the gaps are not clear where the implemented water (blue) and ecological (green) ...infrastructure might help to improve the ecosystem services. We selected mega-city Beijing, the pioneer of the “Ecological Priority” strategy, as the study area. We evaluated the conformance and performance of Beijing's water-related ecological planning implementation on ecological effectiveness from 2000 to 2015. The morphological spatial pattern analysis (MSPA) method was used to extract the blue-green ecological source areas to conform with blue-green plannings. Support, regulation and supply ecosystem services were simulated to integrate ecological effectiveness and its temporal-spatial dynamics. The results show a gradual increase in the proportion of spatial conformance, which remained higher than that of spatial low conformance. The trend of the performance of the implementation based on the analysis of ecosystem services decreased. Our results will help inform upcoming actions related to blue-green planning and management in mega-cities.
In this article, the optimal configuration of the stator for the dual-permanent-magnet vernier machine (DPMVM) is investigated. A novel numerical model used to perform the optimization and compare ...the performances between different permanent magnet (PM) arrangements on the stator part is first presented in this article. According to the proposed numerical model, the effects of the location of PMs at different positions of the stator are studied in terms of output torque, torque ripple, efficiency, and power factor (PF). It is found that the PMs at stator slots contribute more to the output torque than PMs on stator teeth. Moreover, it is found that the stator PMs will add extra cogging torque to the machine compared with the rotor-PM machine. The PF of the dual-PM machine with the combination of the selected stator slots and rotor poles can be higher than 0.9, which is relatively higher compared with both the rotor-PM machine and stator-PM machine.
Vernier permanent-magnet (VPM) machines which have high torque density and high efficiency have been extensively used in direct drive. This article attempts to propose a new winding form and compare ...it with a traditional winding form as a part of fractional slot winding in the VPM machines to provide a design guideline in the aspect. Different winding forms are compared with the same copper loss and the same design. The design guideline of winding forms is provided by multiobjective generation algorithm (GA) optimization. Maximum torque value and minimum torque ripple are the optimization objectives in the GA optimization process. In addition, several models of the modularized motor with the new winding form based on the fractional-slot windings are compared, and the suitable application range of these models are discussed.
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