Cancers are caused by mutations that may be inherited, induced by environmental factors, or result from DNA replication errors (R). We studied the relationship between the number of normal stem cell ...divisions and the risk of 17 cancer types in 69 countries throughout the world. The data revealed a strong correlation (median = 0.80) between cancer incidence and normal stem cell divisions in all countries, regardless of their environment. The major role of R mutations in cancer etiology was supported by an independent approach, based solely on cancer genome sequencing and epidemiological data, which suggested that R mutations are responsible for two-thirds of the mutations in human cancers. All of these results are consistent with epidemiological estimates of the fraction of cancers that can be prevented by changes in the environment. Moreover, they accentuate the importance of early detection and intervention to reduce deaths from the many cancers arising from unavoidable R mutations.
The reaction of precursors containing both nitrogen and oxygen atoms with NiII under 500 °C can generate a N/O mixing coordinated Ni‐N3O single‐atom catalyst (SAC) in which the oxygen atom can be ...gradually removed under high temperature due to the weaker Ni−O interaction, resulting in a vacancy‐defect Ni‐N3‐V SAC at Ni site under 800 °C. For the reaction of NiII with the precursor simply containing nitrogen atoms, only a no‐vacancy‐defect Ni‐N4 SAC was obtained. Experimental and DFT calculations reveal that the presence of a vacancy‐defect in Ni‐N3‐V SAC can dramatically boost the electrocatalytic activity for CO2 reduction, with extremely high CO2 reduction current density of 65 mA cm−2 and high Faradaic efficiency over 90 % at −0.9 V vs. RHE, as well as a record high turnover frequency of 1.35×105 h−1, much higher than those of Ni‐N4 SAC, and being one of the best reported electrocatalysts for CO2‐to‐CO conversion to date.
A vacancy defect was controllably constructed at the Ni site in a nickel single‐atom catalyst. It shows significantly enhanced electrocatalytic activity and selectivity for CO2‐to‐CO conversion compared with the Ni‐N4 catalyst.
This brief proposes a new neural-network (NN)-based adaptive output tracking control scheme for a class of disturbed multiple-input multiple-output uncertain nonlinear switched systems with input ...delays. By combining the universal approximation ability of radial basis function NNs and adaptive backstepping recursive design with an improved multiple Lyapunov function (MLF) scheme, a novel adaptive neural output tracking controller design method is presented for the switched system. The feature of the developed design is that different coordinate transformations are adopted to overcome the conservativeness caused by adopting a common coordinate transformation for all subsystems. It is shown that all the variables of the resulting closed-loop system are semiglobally uniformly ultimately bounded under a class of switching signals in the presence of MLF and that the system output can follow the desired reference signal. To demonstrate the practicability of the obtained result, an adaptive neural output tracking controller is designed for a mass-spring-damper system.
The catalytic activity of metal clusters is closely related with the support; however, knowledge on the influence of the support on the catalytic activity is scarce. We demonstrate that Pt ...nanoclusters (NCs) anchored on porous TiO2 nanosheets with rich oxygen vacancies (VO‐rich Pt/TiO2) and deficient oxygen vacancies (VO‐deficient Pt/TiO2), display significantly different catalytic activity for the hydrogen evolution reaction (HER), in which VO‐rich Pt/TiO2 shows a mass activity of 45.28 A mgPt−1 at −0.1 V vs. RHE, which is 16.7 and 58.8 times higher than those of VO‐deficient Pt/TiO2 and commercial Pt/C, respectively. DFT calculations and in situ Raman spectra suggest that porous TiO2 with rich oxygen vacancies can simultaneously achieve reversed charge transfer (electrons transfer from TiO2 to Pt NCs) and enhanced hydrogen spillover from Pt NCs to the TiO2 support, which leads to electron‐rich Pt NCs being amenable to proton reduction of absorbed H*, as well as the acceleration of hydrogen desorption at Pt catalytic sites—both promoting the HER. Our work provides a new strategy for rational design of highly efficient HER catalysts.
The formation of oxygen vacancies in VO‐rich Pt/TiO2 optimizes the Gibbs free energy for hydrogen intermediate adsorption on Pt clusters, and promotes the hydrogen spillover effect from Pt clusters to the TiO2 support, which boosts the electrocatalytic hydrogen evolution reaction.
Two Pt single‐atom catalysts (SACs) of Pt‐GDY1 and Pt‐GDY2 were prepared on graphdiyne (GDY)supports. The isolated Pt atoms are dispersed on GDY through the coordination interactions between Pt atoms ...and alkynyl C atoms in GDY, with the formation of five‐coordinated C1‐Pt‐Cl4 species in Pt‐GDY1 and four‐coordinated C2‐Pt‐Cl2 species in Pt‐GDY2. Pt‐GDY2 shows exceptionally high catalytic activity for the hydrogen evolution reaction (HER), with a mass activity up to 3.3 and 26.9 times more active than Pt‐GDY1 and the state‐of‐the‐art commercial Pt/C catalysts, respectively. Pt‐GDY2 possesses higher total unoccupied density of states of Pt 5d orbital and close to zero value of Gibbs free energy of the hydrogen adsorption (|ΔGPtH*
|) at the Pt active sites, which are responsible for its excellent catalytic performance. This work can help better understand the structure–catalytic activity relationship in Pt SACs.
All by their selves: Two Pt single‐atom catalysts, anchored on the support of graphdiyne with tuned coordination environments, were developed. Their structure–catalytic performance relationship for hydrogen evolution were investigated.
This study investigated the relationships among specific technostress inhibitors (literacy facilitation, technical support provision, and involvement facilitation) and creators (techno-overload, ...techno-complexity, techno-insecurity, and techno-uncertainty) and their impacts on university teachers’ work performance in higher education. Data from 312 university teachers were analyzed through partial least squares structural equation modelling. The findings indicate that involvement facilitation, in particular, and technical support provision might have significantly curbing effects on three technostress creators (techno-overload, techno-complexity, and techno-insecurity). However, literacy facilitation as one technostress inhibitor might stimulate the development of technostress creators. As to the effect of technostress on university teachers’ work performance, techno-complexity and techno-insecurity had significant negative influence on their work performance. Nevertheless, techno-overload as one technostress creator was positively associated with their work performance. Meanwhile, literacy facilitation and involvement facilitation demonstrated positive effects on university teachers’ work performance. Additionally, the group comparison between young and senior university teachers suggested that literacy facilitation might more greatly boost two technostress creators (techno-overload and techno-complexity) for senior teachers than young teachers. Nonetheless, no gender difference was observed among university teachers in suffering from technostress. This study’s findings provide evidence-based support for policymakers and information and communication technology (ICT) providers in higher education to develop strategies for effective ICT integration in learning and teaching by accounting for university teachers’ technostress in the use of ICT in their work.
Accurate whole-body multi-person pose estimation and tracking is an important yet challenging topic in computer vision. To capture the subtle actions of humans for complex behavior analysis, ...whole-body pose estimation including the face, body, hand and foot is essential over conventional body-only pose estimation. In this article, we present AlphaPose, a system that can perform accurate whole-body pose estimation and tracking jointly while running in realtime. To this end, we propose several new techniques: Symmetric Integral Keypoint Regression (SIKR) for fast and fine localization, Parametric Pose Non-Maximum-Suppression (P-NMS) for eliminating redundant human detections and Pose Aware Identity Embedding for jointly pose estimation and tracking. During training, we resort to Part-Guided Proposal Generator (PGPG) and multi-domain knowledge distillation to further improve the accuracy. Our method is able to localize whole-body keypoints accurately and tracks humans simultaneously given inaccurate bounding boxes and redundant detections. We show a significant improvement over current state-of-the-art methods in both speed and accuracy on COCO-wholebody, COCO, PoseTrack, and our proposed Halpe-FullBody pose estimation dataset. Our model, source codes and dataset are made publicly available at https://github.com/MVIG-SJTU/AlphaPose .
Ternary transition metal chalcogenides (TTMDCs), a novel type of two-dimensional (2D) three-element materials, possess multiple physical and chemical properties and have promising potentials in basic ...physics and devices. Herein, the usage of WxNb(1−x)Se2 nanosheets as a rising ultrafast photonic device to generate high power mode-locked and Q-switched pulses in a fiber laser is demonstrated. The WxNb(1−x)Se2 nanosheets were successfully prepared by the liquid exfoliation method with thickness less than 3 nm. The nonlinear optical absorption of the WxNb(1−x)Se2-based device was investigated with the saturable intensity of 40.93 MW cm−2 and modulation depth of 5.43%. After integrating the WxNb(1−x)Se2-based device into an Er-doped fiber (EDF) laser cavity, mode-locking and Q-switching laser pulses were formed. In the mode-locked mechanism output, the pulse width is as narrow as 131 fs and the output power is 52.93 mW. In Q-switched operation, the shortest pulse duration is 1.47 μs with the largest pulse energy of 257 nJ. Compared to recent studies, our results showed some improvements. This study suggests that 2D TTMDC-based devices could be developed as efficient ultrafast photonics candidates and widely used in nonlinear optical applications.
Filterless narrowband photodetectors can realize color discrimination without filter or bulk spectrometer, thus greatly reducing the system volume and cost for many imaging applications. Charge ...collection narrowing has been demonstrated to be a successful approach to achieve filterless narrowband photodetections; nevertheless, it sacrifices the sensitivity of the photodetectors. Here we show a highly tunable narrowband photodetector based on two-dimensional perovskite single crystals with high external quantum efficiency (200%), ultralow dark current (10
A), and high on-off ratio (10
). The spectral response of the narrowband photodetectors can be continuously tuned from red to blue with all full-width at half-maximum < 60 nm and especially < 20 nm in blue wavelength range. The excellent performance can be ascribed to self-trapped states within bandgap and extremely low electrical conductivity in the out-of-plane direction. Our findings open the exciting potential of 2D perovskites for next-generation optoelectronics.
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