Recent studies have indicated that the architectures of convolutional neural networks (CNNs) tailored for computer vision may not be best suited to image steganalysis. In this letter, we report a CNN ...architecture that takes into account knowledge of steganalysis. In the detailed architecture, we take absolute values of elements in the feature maps generated from the first convolutional layer to facilitate and improve statistical modeling in the subsequent layers; to prevent overfitting, we constrain the range of data values with the saturation regions of hyperbolic tangent (TanH) at early stages of the networks and reduce the strength of modeling using 1×1 convolutions in deeper layers. Although it learns from only one type of noise residual, the proposed CNN is competitive in terms of detection performance compared with the SRM with ensemble classifiers on the BOSSbase for detecting S-UNIWARD and HILL. The results have implied that well-designed CNNs have the potential to provide a better detection performance in the future.
Thermal conductivity is one of the most fundamental properties of solid materials. The thermal conductivity of ideal crystal materials has been widely studied over the past hundreds years. On the ...contrary, for amorphous materials that have valuable applications in flexible electronics, wearable electrics, artificial intelligence chips, thermal protection, advanced detectors, thermoelectrics, and other fields, their thermal properties are relatively rarely reported. Moreover, recent research indicates that the thermal conductivity of amorphous materials is quite different from that of ideal crystal materials. In this article, the authors systematically review the fundamental physical aspects of thermal conductivity in amorphous materials. They discuss the method to distinguish the different heat carriers (propagons, diffusons, and locons) and the relative contribution from them to thermal conductivity. In addition, various influencing factors, such as size, temperature, and interfaces, are addressed, and a series of interesting anomalies are presented. Finally, the authors discuss a number of open problems on thermal conductivity of amorphous materials and a brief summary is provided.
A systematic review of the fundamental physical aspects of thermal conductivity in amorphous materials, which have valuable applications in flexible electronics, artificial intelligence chips, thermal protection, and thermoelectrics, is presented. The contributions from different heat carriers, including propagons, diffusons, and locons, are comprehensively discussed. Various influencing factors are addressed, and a series of interesting anomalies are presented.
The demands for waste heat energy recovery from industrial production, solar energy, and electronic devices have resulted in increasing attention being focused on thermoelectric materials. Over the ...past two decades, significant progress is achieved in inorganic thermoelectric materials. In addition, with the proliferation of wireless mobile devices, economical, efficient, lightweight, and bio‐friendly organic thermoelectric (OTE) materials have gradually become promising candidates for thermoelectric devices used in room‐temperature environments. With the development of experimental measurement techniques, the manufacturing for nanoscale thermoelectric devices has become possible. A large number of studies have demonstrated the excellent performance of nanoscale thermoelectric devices, and further improvement of their thermoelectric conversion efficiency is expected to have a significant impact on global energy consumption. Here, the development of experimental measurement methods, theoretical models, and performance modulation for nanoscale OTE materials are summarized. Suggestions and prospects for the future development of these devices are also provided.
Organic thermoelectric (OTE) devices play an important role in developing novel thermoelectric devices. Here, the progresses of nanoscale OTE devices from the aspects of structural, materials, measurement, and theoretical methods, as well as some typical optimization strategies are reviewed, and an outlook is given to provide an inspiration for the future development of OTE devices.
Immunotherapy aiming at suppressing tumor development by relying on modifying or strengthening the immune system prevails among cancer treatments and points out a new direction for cancer therapy. B7 ...homolog 3 protein (B7-H3, also known as CD276), a newly identified immunoregulatory protein member of the B7 family, is an attractive and promising target for cancer immunotherapy because it is overexpressed in tumor tissues while showing limited expression in normal tissues and participating in tumor microenvironment (TME) shaping and development. Thus far, numerous B7-H3-based immunotherapy strategies have demonstrated potent antitumor activity and acceptable safety profiles in preclinical models. Herein, we present the expression and biological function of B7-H3 in distinct cancer and normal cells, as well as B7-H3-mediated signal pathways in cancer cells and B7-H3-based tumor immunotherapy strategies. This review provides a comprehensive overview that encompasses B7-H3's role in TME to its potential as a target in cancer immunotherapy.
Abstract
The lack of highly efficient, inexpensive catalysts severely hinders large-scale application of electrochemical hydrogen evolution reaction (HER) for producing hydrogen. MoS
2
as a low-cost ...candidate suffers from low catalytic performance. Herein, taking advantage of its tri-layer structure, we report a MoS
2
nanofoam catalyst co-confining selenium in surface and cobalt in inner layer, exhibiting an ultra-high large-current-density HER activity surpassing all previously reported heteroatom-doped MoS
2
. At a large current density of 1000 mA cm
−2
, a much lower overpotential of 382 mV than that of 671 mV over commercial Pt/C catalyst is achieved and stably maintained for 360 hours without decay. First-principles calculations demonstrate that inner layer-confined cobalt atoms stimulate neighbouring sulfur atoms while surface-confined selenium atoms stabilize the structure, which cooperatively enable the massive generation of both in-plane and edge active sites with optimized hydrogen adsorption activity. This strategy provides a viable route for developing MoS
2
-based catalysts for industrial HER applications.
The development of high-performance memory devices has played a key role in the innovation of modern electronics. Non-volatile memory devices have manifested high capacity and mechanical reliability ...as a mainstream technology; however, their performance has been hampered by low extinction ratio and slow operational speed. Despite substantial efforts to improve these characteristics, typical write times of hundreds of micro- or milliseconds remain a few orders of magnitude longer than that of their volatile counterparts. Here we demonstrate non-volatile, floating-gate memory devices based on van der Waals heterostructures with atomically sharp interfaces between different functional elements, achieving ultrahigh-speed programming/erasing operations in the range of nanoseconds with extinction ratio up to 10
. This enhanced performance enables new device capabilities such as multi-bit storage, thus opening up applications in the realm of modern nanoelectronics and offering future fabrication guidelines for device scale up.
The interest in mid-infrared technologies surrounds plenty of important optoelectronic applications ranging from optical communications, biomedical imaging to night vision cameras, and so on. ...Although narrow bandgap semiconductors, such as Mercury Cadmium Telluride and Indium Antimonide, and quantum superlattices based on inter-subband transitions in wide bandgap semiconductors, have been employed for mid-infrared applications, it remains a daunting challenge to search for other materials that possess suitable bandgaps in this wavelength range. Here, we demonstrate experimentally for the first time that two-dimensional (2D) atomically thin PtSe
has a variable bandgap in the mid-infrared via layer and defect engineering. Here, we show that bilayer PtSe
combined with defects modulation possesses strong light absorption in the mid-infrared region, and we realize a mid-infrared photoconductive detector operating in a broadband mid-infrared range. Our results pave the way for atomically thin 2D noble metal dichalcogenides to be employed in high-performance mid-infrared optoelectronic devices.
Abstract
The discovery of ferromagnetic two-dimensional van der Waals materials has opened up opportunities to explore intriguing physics and to develop innovative spintronic devices. However, ...controllable synthesis of these 2D ferromagnets and enhancing their stability under ambient conditions remain challenging. Here, we report chemical vapor deposition growth of air-stable 2D metallic 1T-CrTe
2
ultrathin crystals with controlled thickness. Their long-range ferromagnetic ordering is confirmed by a robust anomalous Hall effect, which has seldom been observed in other layered 2D materials grown by chemical vapor deposition. With reducing the thickness of 1T-CrTe
2
from tens of nanometers to several nanometers, the easy axis changes from in-plane to out-of-plane. Monotonic increase of Curie temperature with the thickness decreasing from ~130.0 to ~7.6 nm is observed. Theoretical calculations indicate that the weakening of the Coulomb screening in the two-dimensional limit plays a crucial role in the change of magnetic properties.
Formic acid (or formate) is suggested to be one of the most economically viable products from electrochemical carbon dioxide reduction. However, its commercial viability hinges on the development of ...highly active and selective electrocatalysts. Here we report that structural defects have a profound positive impact on the electrocatalytic performance of bismuth. Bismuth oxide double-walled nanotubes with fragmented surface are prepared as a template, and are cathodically converted to defective bismuth nanotubes. This converted electrocatalyst enables carbon dioxide reduction to formate with excellent activity, selectivity and stability. Most significantly, its current density reaches ~288 mA cm
at -0.61 V versus reversible hydrogen electrode within a flow cell reactor under ambient conditions. Using density functional theory calculations, the excellent activity and selectivity are rationalized as the outcome of abundant defective bismuth sites that stabilize the *OCHO intermediate. Furthermore, this electrocatalyst is coupled with silicon photocathodes and achieves high-performance photoelectrochemical carbon dioxide reduction.
Abstract
Uncovering the dynamics of active sites in the working conditions is crucial to realizing increased activity, enhanced stability and reduced cost of oxygen evolution reaction (OER) ...electrocatalysts in proton exchange membrane electrolytes. Herein, we identify at the atomic level potential-driven dynamic-coupling oxygen on atomically dispersed hetero-nitrogen-configured Ir sites (AD-HN-Ir) in the OER working conditions to successfully provide the atomically dispersed Ir electrocatalyst with ultrahigh electrochemical acidic OER activity. Using in-situ synchrotron radiation infrared and X-ray absorption spectroscopies, we directly observe that one oxygen atom is formed at the Ir active site with an O-hetero-Ir-N
4
structure as a more electrophilic active centre in the experiment, which effectively promotes the generation of key *OOH intermediates under working potentials; this process is favourable for the dissociation of H
2
O over Ir active sites and resistance to over-oxidation and dissolution of the active sites. The optimal AD-HN-Ir electrocatalyst delivers a large mass activity of 2860 A g
metal
−1
and a large turnover frequency of 5110 h
−1
at a low overpotential of 216 mV (10 mA cm
−2
), 480–510 times larger than those of the commercial IrO
2
. More importantly, the AD-HN-Ir electrocatalyst shows no evident deactivation after continuous 100 h OER operation in an acidic medium.
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