Abstract
Lithium-sulfur batteries show great potential to achieve high-energy-density storage, but their long-term stability is still limited due to the shuttle effect caused by the dissolution of ...polysulfides into electrolyte. Herein, we report a strategy of significantly improving the polysulfides adsorption capability of cobaltous oxide by amorphization-induced surface electronic states modulation. The amorphous cobaltous oxide nanosheets as the cathode additives for lithium-sulfur batteries demonstrates the rate capability and cycling stability with an initial capacity of 1248.2 mAh g
-1
at 1 C and a substantial capacity retention of 1037.3 mAh g
-1
after 500 cycles. X-ray absorption spectroscopy analysis reveal that the coordination structures and symmetry of ligand field around Co atoms of cobaltous oxide nanosheets are notably changed after amorphization. Moreover, DFT studies further indicate that amorphization-induced re-distribution of
d
orbital makes more electrons occupy high energy level, thereby resulting in a high binding energy with polysulfides for favorable adsorption.
Noble metal nanomaterials have been widely used as catalysts. Common techniques for the synthesis of noble metal often result in crystalline nanostructures. The synthesis of amorphous noble metal ...nanostructures remains a substantial challenge. We present a general route for preparing dozens of different amorphous noble metal nanosheets with thickness less than 10 nm by directly annealing the mixture of metal acetylacetonate and alkali salts. Tuning atom arrangement of the noble metals enables to optimize their catalytic properties. Amorphous Ir nanosheets exhibit a superior performance for oxygen evolution reaction under acidic media, achieving 2.5-fold, 17.6-fold improvement in mass activity (at 1.53 V vs. reversible hydrogen electrode) over crystalline Ir nanosheets and commercial IrO
catalyst, respectively. In situ X-ray absorption fine structure spectra indicate the valance state of Ir increased to less than + 4 during the oxygen evolution reaction process and recover to its initial state after the reaction.
The sintering of supported metal nanoparticles is a major route to the deactivation of industrial heterogeneous catalysts, which largely increase the cost and decrease the productivity. Here, we ...discover that supported palladium/gold/platinum nanoparticles distributed at the interface of oxide supports and nitrogen-doped carbon shells would undergo an unexpected nitrogen-doped carbon atomization process against the sintering at high temperatures, during which the nanoparticles can be transformed into more active atomic species. The in situ transmission electron microscopy images reveal the abundant nitrogen defects in carbon shells provide atomic diffusion sites for the mobile atomistic palladium species detached from the palladium nanoparticles. More important, the catalytic activity of sintered and deactivated palladium catalyst can be recovered by this unique N-doped carbon atomization process. Our findings open up a window to preparation of sintering-resistant single atoms catalysts and regeneration of deactivated industrial catalysts.
Vesicular neurotransmitter transporters (VNTs) mediate the selective uptake and enrichment of small-molecule neurotransmitters into synaptic vesicles (SVs) and are therefore a major determinant of ...the synaptic output of specific neurons. To identify novel VNTs expressed on SVs (thus identifying new neurotransmitters and/or neuromodulators), we conducted localization profiling of 361 solute carrier (SLC) transporters tagging with a fluorescent protein in neurons, which revealed 40 possible candidates through comparison with a known SV marker. We parallelly performed proteomics analysis of immunoisolated SVs and identified seven transporters in overlap. Ultrastructural analysis further supported that one of the transporters, SLC35D3, localized to SVs. Finally, by combining metabolite profiling with a radiolabeled substrate transport assay, we identified UDP-glucose as the principal substrate for SLC35D3. These results provide new insights into the functional role of SLC transporters in neurotransmission and improve our understanding of the molecular diversity of chemical transmitters.
The correct establishment and maintenance of unidirectional Notch signaling are critical for the homeostasis of various stem cell lineages. However, the molecular mechanisms that prevent ...cell-autonomous ectopic Notch signaling activation and deleterious cell fate decisions remain unclear. Here we show that the retromer complex directly and specifically regulates Notch receptor retrograde trafficking in
neuroblast lineages to ensure the unidirectional Notch signaling from neural progenitors to neuroblasts. Notch polyubiquitination mediated by E3 ubiquitin ligase Itch/Su(dx) is inherently inefficient within neural progenitors, relying on retromer-mediated trafficking to avoid aberrant endosomal accumulation of Notch and cell-autonomous signaling activation. Upon retromer dysfunction, hypo-ubiquitinated Notch accumulates in Rab7
enlarged endosomes, where it is ectopically processed and activated in a ligand-dependent manner, causing progenitor-originated tumorigenesis. Our results therefore unveil a safeguard mechanism whereby retromer retrieves potentially harmful Notch receptors in a timely manner to prevent aberrant Notch activation-induced neural progenitor dedifferentiation and brain tumor formation.
Represented by reactive security defense mechanisms, cyber defense possesses a static, reactive, and deterministic nature, with overwhelmingly high costs to defend against ever-changing attackers. To ...change this situation, researchers have proposed moving target defense (MTD), which introduces the concept of an attack surface to define cyber defense in a brand-new manner, aiming to provide a dynamic, continuous, and proactive defense mechanism. With the increasing use of machine learning in networking, researchers have discovered that MTD techniques based on machine learning can provide omni-bearing defense capabilities and reduce defense costs at multiple levels. However, research in this area remains incomplete and fragmented, and significant progress is yet to be made in constructing a defense mechanism that is both robust and available. Therefore, we conducted a comprehensive survey on MTD research, summarizing the background, design mechanisms, and shortcomings of MTD, as well as relevant features of intelligent MTD that are designed to overcome these limitations. We aim to provide researchers seeking the future development of MTD with insight into building an intelligently affordable, optimized, and self-adaptive defense mechanism.
Two-dimensional noble metal nanomaterials(2D NMNs) are widely used as electrocatalyst. In recent years, the researchers have focused on the synthesis of 2D NMNs at the atomic scale, and realize the ...improvement of electrocatalytic performance through further structural modification to reduce the usage of noble metals. Herein, we systematically introduce the synthesis methods of 2D NMNs categorized by element type. Subsequently, the catalytic applications toward a variety of electrocatalytic reactions are described in detail including the hydrogen evolution reaction(HER), oxygen reduction reaction(ORR), oxygen evolution reaction(OER) and CO
2
reduction reaction (CO
2
RR). Finally, the potential opportunities and remaining challenges in this emerging research area are proposed.
API calls are programming interfaces used by applications. When it is difficult for an analyst to perform a direct reverse analysis of a program, the API provides an important basis for analyzing the ...behavior and functionality of the program. API address spaces are essential for analysts to identify API call information, and therefore API call obfuscation is used as a protection strategy to prevent analysts from obtaining call information from API address spaces. API call obfuscation avoids direct API calls and aims to create a more complex API calling process. Unfortunately, current API call obfuscation methods are not effective in preventing analysts from obtaining usable information from the API address space. To solve this issue, in this paper, we propose an API call obfuscation model based on address space obscurity. The key functions within the API are encrypted and moved to the user code space for execution. This breaks the relationship between the API and its address space, making it impossible for analysts to obtain address information about a known API from the API address space. In our experiments, we developed an archetypical compiler-level API call obfuscation system to automate the obfuscation of input source code into an obfuscated file. The results show that our approach can thwart existing API deobfuscation techniques and is highly resistant to various open-source dynamic analysis platforms. Compared to other obfuscation techniques, our scheme improves API address space obscurity by more than two times, the detection rate of deobfuscation techniques such as Scylla, etc. is zero, and the increase in obfuscation overhead is not more than 20%. The above results show that APIASO has better obfuscation effect and practicability.
Background The temporal sequence between serum calcium and insulin resistance (IR) and their effects on hypertension are unclear. We studied the association between serum calcium and IR, with risk of ...hypertension events in a longitudinal cohort conducted in China. Methods and Results Data from 8653 subjects aged 20 to 74 years with an average follow-up of 5.3 years were analyzed. Serum calcium, and fasting and 2-hour serum glucose and insulin were measured at baseline and follow-up. Cross-lagged panel and mediation analysis were used to examine the temporal relationship between serum calcium and IR and its impact on hypertension incidence. The conjoint effects of serum calcium and IR at baseline on hypertension at follow-up were observed ( P=0.029 for HOMA_IR hepatic IR and P=0.009 for Gutt index peripheral IR). The cross-lagged path coefficient (β
) from baseline serum calcium to follow-up peripheral IR were significantly greater than path coefficient (β
) from baseline peripheral insulin resistance to follow-up serum calcium (β
=-0.354 versus β
=-0.005; P=0.027). However, no directional relationships were observed in the serum calcium↔hepatic IR analysis. The mediation effect of peripheral IR on the association of serum calcium at baseline with hypertension at follow-up was estimated at 16.4% ( P<0.001). Conclusions Our findings demonstrate that higher serum calcium levels probably precede peripheral IR, and this 1-directional relation plays a role in the development of hypertension.
Achieving high selectivity and activity with the oxygen reduction reaction (ORR) is significant for developing efficient energy conversion techniques and chemical production. Here, we report that ...selective ORRs can be achieved by tuning short-range order in amorphous and crystalline NiO nanosheets (a-NiO NSs and c-NiO NSs, respectively). X-ray absorption spectroscopy analysis reveals that the short-range order of a-NiO NSs and c-NiO NSs mainly adopt the NiO5 pyramidal and NiO6 octahedral structures, respectively. The a-NiO NSs for electrochemical H2O2 production in 0.1 M KOH exhibits both high selectivity over 90% and high activity (1 mA cm−2 at 0.66 V versus RHE), while c-NiO NSs tends to catalyze ORRs through 4-electron pathways to generate H2O. Theoretical calculations indicate that the changed short-range order of a-NiO NSs leads to alteration of Ni d-orbital states, which can regulate the adsorption orientation and strength of ∗OOH intermediates to achieve high selectivity and activity of 2-electron ORRs.
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•A facile method for preparing low-cost electrocatalyst for H2O2 production•Achieve selective 2-electron and 4-electron ORRs by tuning short-range order•Insights on structure-property relationship of the ORR
Controlling the selectivity and activity of the oxygen reduction reaction (ORR) is essential to improve the efficiency of energy conversion and chemical production. Li et al. report that highly selective and active ORR catalysts can be prepared by tuning short-range order in amorphous and crystalline NiO nanosheets.
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