267 research outputs found
Evidence of local superconductivity in granular Bi nanowires fabricated by electrodeposition
An unusual enhancement of resistance (i.e., superresistivity) below a certain
characteristic temperature Tsr was observed in granular Bi nanowires. This
superresistive state was found to be dependent on the applied magnetic field
(H) as well as the excitation current (I). The suppression of Tsr by magnetic
field resembles that of a superconductor. The observed superresistivity appears
to be related to the nucleation of local superconductivity inside the granular
nanowire without long-range phase coherence. The phenomenon is reminiscent of
the Bose-insulator observed previously in ultra thin two-dimensional (2D)
superconducting films and 3D percolative superconducting films.Comment: 11 pages, 5 figures. submitted to PR
Metal-free photo-induced sulfidation of aryl iodide and other chalcogenation
A photo-induced C-S radical cross-coupling of aryl iodides and disulfides under transition-metal and external photosensitizer free conditions for the synthesis of aryl sulfides at room temperature has been presented, which features mild reaction conditions, broad substrate scope, high efficiency, and good functional group compatibility. The developed methodology could be readily applied to forge C-S bond in the field of pharmaceutical and material science
Doublade: Unknown Vulnerability Detection in Smart Contracts Via Abstract Signature Matching and Refined Detection Rules
With the prosperity of smart contracts and the blockchain technology, various
security analyzers have been proposed from both the academia and industry to
address the associated risks. Yet, there does not exist a high-quality
benchmark of smart contract vulnerability for security research. In this study,
we propose an approach towards building a high-quality vulnerability benchmark.
Our approach consists of two parts. First, to improve recall, we propose to
search for similar vulnerabilities in an automated way by leveraging the
abstract vulnerability signature (AVS). Second, to remove the false positives
(FPs) due to AVS-based matching, we summarize the detection rules of existing
tools and apply the refined rules by considering various defense mechanisms
(DMs). By integrating AVS-based code matching and the refined detection rules
(RDR), our approach achieves higher precision and recall. On the collected
76,354 contracts, we build a benchmark consisting of 1,219 vulnerabilities
covering five different vulnerability types identified together by our tool
(DOUBLADE) and other three scanners. Additionally, we conduct a comparison
between DOUBLADE and the others, on an additional 17,770 contracts. Results
show that DOUBLADE can yield a better detection accuracy with similar execution
time
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Pancreatic β cells control glucose homeostasis via the secretion of exosomal miR-29 family.
Secreted microRNAs (miRNAs) are novel endocrine factors that play essential pathological and physiological roles. Here, we report that pancreatic β cell-released exosomal miR-29 family members (miR-29s) regulate hepatic insulin sensitivity and control glucose homeostasis. Cultured pancreatic islets were shown to secrete miR-29s in response to high levels of free fatty acids (FFAs) in vitro. In vivo, high levels of FFAs, promoted by either high-fat diet (HFD) feeding (physiopathological) or fasting (physiological), increased the secretion of miR-29s into plasma. Intravenous administration of exosomal miR-29s attenuated insulin sensitivity. The overexpression of miR-29s in the β cells of transgenic (TG) mice promoted the secretion of miR-29s and inhibited the insulin-mediated suppression of glucose output in the liver. We used selective overexpression of traceable heterogenous mutant miR-29s in β cells to confirm that islet-derived exosomal miR-29s target insulin signalling in the liver and blunt hepatic insulin sensitivity. Moreover, in vivo disruption of miR-29s expression in β cells reversed HFD-induced insulin resistance. In vitro experiments demonstrated that isolated exosomes enriched in miR-29s inhibited insulin signalling in the liver and increased hepatic glucose production. These results unveil a novel β cell-derived secretory signal-exosomal miR-29s-and provide insight into the roles of miR-29s in manipulating glucose homeostasis.MRC MD
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