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"Yang, Dan"
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A flexible ultrasensitive optoelectronic sensor array for neuromorphic vision systems
The challenges of developing neuromorphic vision systems inspired by the human eye come not only from how to recreate the flexibility, sophistication, and adaptability of animal systems, but also how to do so with computational efficiency and elegance. Similar to biological systems, these neuromorphic circuits integrate functions of image sensing, memory and processing into the device, and process continuous analog brightness signal in real-time. High-integration, flexibility and ultra-sensitivity are essential for practical artificial vision systems that attempt to emulate biological processing. Here, we present a flexible optoelectronic sensor array of 1024 pixels using a combination of carbon nanotubes and perovskite quantum dots as active materials for an efficient neuromorphic vision system. The device has an extraordinary sensitivity to light with a responsivity of 5.1 × 10
7
A/W and a specific detectivity of 2 × 10
16
Jones, and demonstrates neuromorphic reinforcement learning by training the sensor array with a weak light pulse of 1 μW/cm
2
.
To emulate nature biological processing, highly-integrated ultra-sensitive artificial neuromorphic system is highly desirable. Here, the authors report flexible sensor array of 1024 pixels using combination of carbon nanotubes and perovskite QDs as active matetials, achieving highly responsive device for reinforcement learning.
Journal Article
الصين، دولة أقرب
يتناول كتاب (الصين، دولة أقرب) في حوالي (154) صفحة من القطع المتوسط أبرز المحتويات التالية : السكك الحديدية عالية السرعة الوجه الجديد لصنع في الصين، السكك الحديدية الأفريقية صنع في الصين، عيد الميلاد من دون صنع في الصين، المعجزة الصينية تقدم حلا لمساعي تخفيف الفقر في العالم، الصين تفي بالتزاماتها لمكافحة التصحر، الصين تحظر تجارة العاج كهدية للعام الجديد للبشرية.
Book
Chlorine disinfection promotes the exchange of antibiotic resistance genes across bacterial genera by natural transformation
Chlorine disinfection to drinking water plays an important role in preventing and controlling waterborne disease outbreaks globally. Nevertheless, little is known about why it enriches the antibiotic resistance genes (ARGs) in bacteria after chlorination. Here, ARGs released from killed antibiotic-resistant bacteria (ARB), and culturable chlorine-injured bacteria produced in the chlorination process as the recipient, were investigated to determine their contribution to the horizontal transfer of ARGs during disinfection treatment. We discovered
Esch
e
richia coli
,
Salmonella aberdeen
,
Pseudomonas aeruginosa
and
Enterococcus faecalis
showed diverse resistance to sodium hypochlorite, and transferable RP4 could be released from killed sensitive donor consistently. Meanwhile, the survival of chlorine-tolerant injured bacteria with enhanced cell membrane permeabilisation and a strong oxidative stress-response demonstrated that a physiologically competent cell could be transferred by RP4 with an improved transformation frequency of up to 550 times compared with the corresponding untreated bacteria. Furthermore, the water quality factors involving chemical oxygen demand (COD
Mn
), ammonium nitrogen and metal ions (Ca
2+
and K
+
) could significantly promote above transformation frequency of released RP4 into injured
E. faecalis
. Our findings demonstrated that the chlorination process promoted the horizontal transfer of plasmids by natural transformation, which resulted in the exchange of ARGs across bacterial genera and the emergence of new ARB, as well as the transfer of chlorine-injured opportunistic pathogen from non-ARB to ARB. Considering that the transfer elements were quite resistant to degradation through disinfection, this situation poses a potential risk to public health.
Journal Article
Circuit-based interrogation of sleep control
Sleep is a fundamental biological process observed widely in the animal kingdom, but the neural circuits generating sleep remain poorly understood. Understanding the brain mechanisms controlling sleep requires the identification of key neurons in the control circuits and mapping of their synaptic connections. Technical innovations over the past decade have greatly facilitated dissection of the sleep circuits. This has set the stage for understanding how a variety of environmental and physiological factors influence sleep. The ability to initiate and terminate sleep on command will also help us to elucidate its functions within and beyond the brain.
Weber and Dan review our understanding of the neural circuits controlling sleep, focusing on the advances in measurement and manipulation of neuronal activity and circuit tracing from genetically defined cell types.
Taking control of the sleep–wake cycle
Our understanding of the neural circuits controlling sleep cycles is still incomplete. The availability of new techniques in optogenetics, pharmacogenetics, microendoscopic calcium imaging and virus-mediated circuit tracing—together with mouse genetics—raise the possibility that many of the mysteries of sleep can be tackled. In a Review in this issue of
Nature
, Franz Weber and Yang Dan explore the current state of sleep circuit research and plot a course directed towards an ambitious goal: a comprehensive circuit diagram of the sleep–wake control network detailing the functional role of each cell type and the interactions between them.
Journal Article
ICOS + Tregs: A Functional Subset of Tregs in Immune Diseases
Recent studies have reported the pathological effect of ICOS
T cells, but ICOS signals also widely participate in anti-inflammatory responses, particularly ICOS
regulatory T (Treg) cells. The ICOS signaling pathway endows Tregs with increased generation, proliferation, and survival abilities. Furthermore, there is enough evidence to suggest a superior capacity of ICOS
Tregs, which is partly attributable to IL-10 induced by ICOS, yet the associated mechanism needs further investigation. In this review, we discuss the complicated role of ICOS
Tregs in several classical autoimmune diseases, allergic diseases, and cancers and investigate the related therapeutic applications in these diseases. Moreover, we identify ICOS as a potential biomarker for disease treatment and prognostic prediction. In addition, we believe that anti-ICOS/ICOSL monoclonal antibodies exhibit excellent clinical application potential. A thorough understanding of the effect of ICOS
Tregs and the holistic role of ICOS toward the immune system will help to improve the therapeutic schedule of diseases.
Journal Article
Electrosynthesis of 1,4-bis(diphenylphosphanyl) tetrasulfide via sulfur radical addition as cathode material for rechargeable lithium battery
Organic electrodes are promising as next generation energy storage materials originating from their enormous chemical diversity and electrochemical specificity. Although organic synthesis methods have been extended to a broad range, facile and selective methods are still needed to expose the corners of chemical space. Herein, we report the organopolysulfide, 1,4-bis(diphenylphosphanyl)tetrasulfide, which is synthesized by electrochemical oxidation of diphenyl dithiophosphinic acid featuring the cleavage of a P–S single bond and a sulfur radical addition reaction. Density functional theory proves that the external electric field triggers the intramolecular rearrangement of diphenyl dithiophosphinic acid through dehydrogenation and sulfur migration along the P–S bond axis. Impressively, the Li/bis(diphenylphosphanyl)tetrasulfide cell exhibits the high discharge voltage of 2.9 V and stable cycling performance of 500 cycles with the capacity retention of 74.8%. Detailed characterizations confirm the reversible lithiation/delithiation process. This work demonstrates that electrochemical synthesis offers the approach for the preparation of advanced functional materials.
Organic electrodes are promising energy storage materials owing to their chemical diversity and electrochemical specificity. Here, the authors report synthesis of phosphorous containing organopolysulfide 1,4-bis(diphenylphosphanyl)tetrasulfide material showing excellent performance in a rechargeable Li battery.
Journal Article
Delay activity of specific prefrontal interneuron subtypes modulates memory-guided behavior
Using calcium imaging and optogenetic manipulation in mice performing a working memory task, the authors show that delay activity in prefrontal cortex pyramidal neurons is crucial for task performance. Optogenetic activation of VIP interneurons enhances the neuronal representation of task-relevant information and improves the animal's memory retention.
Memory-guided behavior requires maintenance of task-relevant information without sensory input, but the underlying circuit mechanism remains unclear. Calcium imaging in mice performing a delayed Go or No-Go task revealed robust delay activity in dorsomedial prefrontal cortex, with different pyramidal neurons signaling Go and No-Go action plans. Inhibiting pyramidal neurons by optogenetically activating somatostatin- or parvalbumin-positive interneurons, even transiently during the delay, impaired task performance, primarily by increasing inappropriate Go responses. In contrast, activating vasoactive intestinal peptide (VIP)-positive interneurons enhanced behavioral performance and neuronal action plan representation. Furthermore, while endogenous activity of somatostatin and parvalbumin neurons was strongly biased toward Go trials, VIP neurons were similarly active in Go and No-Go trials. Somatostatin or VIP neuron activation also impaired or enhanced performance, respectively, in a delayed two-alternative forced-choice task. Thus, dorsomedial prefrontal cortex is a crucial component of the short-term memory network, and activation of its VIP neurons improves memory retention.
Journal Article
Study Partners Recommendation for xMOOCs Learners
Massive open online courses (MOOCs) provide an opportunity for people to access free courses offered by top universities in the world and therefore attracted great attention and engagement from college teachers and students. However, with contrast to large scale enrollment, the completion rate of these courses is really low. One of the reasons for students to quit learning process is problems which they face that could not be solved by discussing them with classmates. In order to keep them staying in the course, thereby further improving the completion rate, we address the task of study partner recommendation for students based on both content information and social network information. By analyzing the content of messages posted by learners in course discussion forum, we investigated the learners’ behavior features to classify the learners into three groups. Then we proposed a topic model to measure learners’ course knowledge awareness. Finally, a social network was constructed based on their activities in the course forum, and the relationship in the network was then employed to recommend study partners for target learner combined with their behavior features and course knowledge awareness. The experiment results show that our method achieves better performance than recommending method only based on content information.
Journal Article
Deep Insight of Design, Mechanism, and Cancer Theranostic Strategy of Nanozymes
HighlightsClassification and catalytic mechanism of nanozymes with different mimicking activities are dissertated.Activity prediction and rational design methods of nanozymes are highlighted, including density functional theory, machine learning, biomimetic and chemical design.The roles of nanozymes in different synergistic theranostic strategies for tumor are summarized and explained by representative examples in the past five years.Since the discovery of enzyme-like activity of Fe3O4 nanoparticles in 2007, nanozymes are becoming the promising substitutes for natural enzymes due to their advantages of high catalytic activity, low cost, mild reaction conditions, good stability, and suitable for large-scale production. Recently, with the cross fusion of nanomedicine and nanocatalysis, nanozyme-based theranostic strategies attract great attention, since the enzymatic reactions can be triggered in the tumor microenvironment to achieve good curative effect with substrate specificity and low side effects. Thus, various nanozymes have been developed and used for tumor therapy. In this review, more than 270 research articles are discussed systematically to present progress in the past five years. First, the discovery and development of nanozymes are summarized. Second, classification and catalytic mechanism of nanozymes are discussed. Third, activity prediction and rational design of nanozymes are focused by highlighting the methods of density functional theory, machine learning, biomimetic and chemical design. Then, synergistic theranostic strategy of nanozymes are introduced. Finally, current challenges and future prospects of nanozymes used for tumor theranostic are outlined, including selectivity, biosafety, repeatability and stability, in-depth catalytic mechanism, predicting and evaluating activities.
Journal Article