Manipulating 2D Materials through Strain Engineering.

This review explores the growing interest in 2D layered materials, such as graphene, h-BN, transition metal dichalcogenides (TMDs), and black phosphorus (BP), with a specific focus on recent advances in strain engineering. Both experimental and theoretical results are delved into, highlighting the potential of strain to modulate physical properties, thereby enhancing device performance. Various strain engineering methods are summarized, and the impact of strain on the electrical, optical, magnetic, thermal, and valleytronic properties of 2D materials is thoroughly examined. Finally, the review concludes by addressing potential applications and challenges in utilizing strain engineering for functional devices, offering valuable insights for further research and applications in optoelectronics, thermionics, and spintronics.

2D van der Waals Vertical Heterojunction Transistors for Ternary Neural Networks.

Compared with binary systems, ternary computing systems can utilize fewer devices to realize the same information density. However, most ternary computing systems based on binary CMOS circuits require additional devices to bridge binary processing and ternary computing. Exploring new device architectures for direct ternary processing and computing becomes the key to promoting ternary computing systems. Here, we demonstrated a 2D van der Waals vertical heterojunction transistor (V-HTR) with three flat conductance states, which can be the basic cell in ternary circuits to perform ternary processing and computing, without additional devices. A ternary neural network (TNN) and a ternary inverter were demonstrated based on the V-HTRs. The TNN can eliminate fuzzy data and output only clear data by building a ternary quantization function. By demonstrating both ternary logic and a TNN on the same device architecture, the 2D V-HTR shows potential as a basic hardware unit for future ternary computing systems.

Towards Optical Information Recording: A Robust Visible-Light-Driven Molecular Photoswitch with the Ring-Closure Reaction Yield Exceeding 96.3 .

Diarylethene molecular photoswitches hold great fascination as optical information materials due to their unique bistability and exceptional reversible photoswitching properties. Conventional diarylethenes, however, rely on UV light for ring-closure reactions, typically with modest yields. For practical application, diarylethenes driven by visible lights are preferred but achieving high ring-closure reaction yield remains a significant challenge. Herein, we synthesized a novel all-visible-light-driven photoswitch, TPAP-DTE, by facilely endcapping the dithienylethene (DTE) core with triphenylamine phenyl (TPAP) groups. Owing to the electron-donating conjugation effect of TPAP, the open-form TPAP-DTE responds strongly to short-wavelength visible lights with considerable photocyclization quantum yields and molar absorption coefficient. Upon 405 nm visible-light irradiation, TPAP-DTE achieves a ring-closure reaction yield exceeding 96.3 % (confirmed by both nuclear magnetic resonance spectroscopy and high-performance liquid chromatography). Its ring-opening reaction yield is 100 % upon irradiation with long-wavelength visible light. TPAP-DTE could be regarded as a bidirectional "quasi"-quantitative conversion molecular switch. Furthermore, TPAP-DTE exhibits robust fatigue resistance over 100 full photoswitching cycles and great anti-aging property under 85 °C and 85 % humidity for at least 1000 h. Consequently, its rewritable QR-code, multilevel data storage, and anti-counterfeiting/encryption applications are successfully demonstrated exclusively using visible lights, positioning TPAP-DTE as a highly promising medium for information recording.

Fast near-infrared photodetectors from p-type SnSe nanoribbons.

Low-dimensional tin selenide nanoribbons (SnSe NRs) show a wide range of applications in optoelectronics fields such as optical switches, photodetectors, and photovoltaic devices due to the suitable band gap, strong light-matter interaction, and high carrier mobility. However, it is still challenging to grow high-quality SnSe NRs for high-performance photodetectors so far. In this work, we successfully synthesized high-quality p-type SnSe NRs by chemical vapor deposition and then fabricated near-infrared photodetectors. The SnSe NR photodetectors show a high responsivity of 376.71 A W-1, external quantum efficiency of 5.65 × 104%, and detectivity of 8.66 × 1011Jones. In addition, the devices show a fast response time with rise and fall time of up to 43µs and 57µs, respectively. Furthermore, the spatially resolved scanning photocurrent mapping shows very strong photocurrent at the metal-semiconductor contact regions, as well as fast generation-recombination photocurrent signals. This work demonstrated that p-type SnSe NRs are promising material candidates for broad-spectrum and fast-response optoelectronic devices.

Small-diameter p-type SnS nanowire photodetectors and phototransistors with low-noise and high-performance.

P-type nanostructured photodetectors and phototransistors have been widely used in the field of photodetection due to their excellent electrical and optoelectronic characteristics. However, the large dark current of p-type photodetectors will limit the detectivity. Herein, we synthesized small-diameter single-crystalline p-type SnS nanowires (NWs) and then fabricated single SnS NW photodetectors and phototransistors. The device exhibits low noise and low dark current, and its noise current power is as low as 2.4 × 10-28A2. Under 830 nm illumination and low power density of 0.12 mW cm-2, the photoconductive gain, responsivity and detectivity of the photodetector are as high as 3.9 × 102, 2.6 × 102A W-1and 1.8 × 1013Jones, respectively, at zero gate voltage. The rise and fall time of response are about 9.6 and 14 ms. The experimental results show that the small-diameter p-type SnS NWs have broad application prospects in high-performance and low-power photodetectors with high sensitivity, fast response speed and wide spectrum detection in the future.

Piezoelectric potential enhanced photocatalytic performance based on ZnO with different nanostructures.

In this paper, two novel nanostructures with ZnO nanowire and nanosheet arrays vertically growing on the FTO and Al foil have been synthesized by a hydrothermal method, which exhibit both the piezoelectric and photocatalytic properties. These nanostructures have typical wurtzite structures based on the XRD results. From the SEM results, the average diameter and length of nanowire have been measured to be about 150 nm and 4.5 µm, the thickness of ZnO nanosheet is about 50 nm and the width is about 5 µm. In the photocatalytic test, the photodegradation of RhB under 365 nm illumination for nanowire and nanosheet is about 25% and 37% in 80 min reaction. With stirring, the degradation rate is increased to 61% and 85%. Finally, the photocurrent test and finite element method were used to analyze the piezo-photodegradation mechanism.

In vivo phenotypic and molecular characterization of retinal degeneration in mouse models of three ciliopathies.

Cilia are highly conserved and ubiquitously expressed organelles. Ciliary defects of genetic origins lead to ciliopathies, in which retinal degeneration (RD) is one cardinal clinical feature. In order to efficiently find and design new therapeutic strategies the underlying mechanism of retinal degeneration of three murine model was compared. The rodent models correspond to three emblematic ciliopathies, namely: Bardet-Biedl Syndrome (BBS), Alström Syndrome (ALMS) and CEP290-mediated Leber Congenital Amaurosis (LCA). Scotopic rodent electroretinography (ERG) was used to test the retinal function of mice, Transmitted Electron microscopy (T.E.M) was performed to assess retinal structural defects and real-time PCR for targeted genes was used to monitor the expression levels of the major apoptotic Caspase-related pathways in retinal extracts to identify pathological pathways driving the RD in order to identify potential therapeutic targets. We found that BBS and CEP290-mediated LCA mouse models exhibit perinatal retinal degeneration associated with rhodopsin mislocalization in the photoreceptor and the induction of an Endoplasmic Reticulum (ER) stress. On the other hand, the tested ALMS mouse model, displayed a slower degeneration phenotype, with no Rhodopsin mislocalization nor ER-stress activity. Our data points out that behind the general phenotype of vision loss associated with these ciliopathies, the mechanisms and kinetics of disease progression are different.

Fabrication of a cost effective and broadband self-powered photodetector based on Sb2Te3 and silicon.

The excellent conductive surface electronic states of topological insulators make them suitable candidates for the next generation optoelectronic devices. Moreover, their unique semiconducting properties are favorable for building heterojunctions with other semiconductors. Here, we fabricated a low cost and broadband self-powered photodetector based on Sb2Te3 and Si. The photolithography and thermal evaporation technique were combined to fabricate a series of asymmetric planar Sb2Te3 electrodes on the surface of an n-type silicon substrate. An obvious asymmetrical current voltage curve occurred under dark conditions, which is ascribed to the asymmetry of each electrode. During the photodetection test, self-powered photodetection was obtained upon 940 nm light irradiation. Moreover, the photodetector exhibited fast and broadband photodetection from 365 nm to 940 nm with a response time less than 40 ms.

Nonlinear optical and multi-photon absorption properties in graphene-ZnO nanocomposites.

Graphene-ZnO (GZO) nanocomposites were synthesized by a modified solvothermal method, and characterized by transmission electron microscopy, x-ray diffraction, Raman spectra, and UV-vis absorption spectra. The controllable nonlinear optical (NLO) properties of as-prepared GZO nanocomposites were tested by an open-aperture Z-scan method with 1030 nm fs laser pulses; the tested results showed that there were five-photon absorption (5PA) at 46.8 GW cm-2, 3PA at 28.1 GW cm-2, 2PA at 18.7 GW cm-2, and a vital change from saturable absorption (SA) to reverse SA (RSA) with the increase of incident intensity. This was the first time that 5PA was found in GZO nanocomposites at such a low intensity, 46.8 GW cm-2. The tunable NLO property from SA to RSA and controllable multi-photon absorption provided a facile approach for their applications in optical, optoelectronic devices, and information storage.

2D Lead Dihalides for High-Performance Ultraviolet Photodetectors and their Detection Mechanism Investigation.

2D halide semiconductors, a new family of 2D materials in addition to transition metal dichalcogenides, present ultralow dark current and high light conversion yield, which hold great potential in photoconductive detectors. Herein, a facile aqueous solution method is developed for the preparation of large-scale 2D lead dihalide nanosheets (PbF2-x Ix ). High-performance UV photodetectors are successfully implemented based on 2D PbF2-x Ix nanosheets. By modulating the components of halogens, the bandgap of PbF2-x Ix nanosheets can be tuned to meet varied detection spectra. The photoresponse dependence on incident power density, wavelength, detection environment, and temperature are systematically studied to investigate their detection mechanism. For PbI2 photodetectors, they are dominantly driven by a photoconduction mechanism and show a fast response speed and a low noise current density. A high normalized detectivity of 1.5 × 1012 Jones and an ION /IOFF ratio up to 103 are reached. On the other hand, PbFI photodetectors demonstrate a photogating mechanism mediated by trap states showing high responsivity. The novel 2D halide materials with wide bandgaps, superior detection performance, and facile synthesis process can enrich the Van der Waals solids family and hold great potential for a wide variety of applications in advanced optoelectronics.

Measurement of nonlinear optical refraction of composite material based on sapphire with silver by Kerr-lens autocorrelation method.

Silver nanoparticles synthesized in a synthetic sapphire matrix were fabricated by ion implantation using the metal vapor vacuum arc ion source. The optical absorption spectrum of the Ag: Al2O3 composite material has been measured. The analysis of the supercontinuum spectrum displayed the nonlinear refractive property of this kind of sample. Nonlinear optical refraction index was identified at 800 nm excitation using the Kerr-lens autocorrelation (KLAC) technique. The spectrum showed that the material possessed self-defocusing property (n(2) = -1.1 × 10(-15) cm(2)W). The mechanism of nonlinear refraction has been discussed.

Multifunctional human visual pathway-replicated hardware based on 2D materials.

Artificial visual system empowered by 2D materials-based hardware simulates the functionalities of the human visual system, leading the forefront of artificial intelligence vision. However, retina-mimicked hardware that has not yet fully emulated the neural circuits of visual pathways is restricted from realizing more complex and special functions. In this work, we proposed a human visual pathway-replicated hardware that consists of crossbar arrays with split floating gate 2D tungsten diselenide (WSe2) unit devices that simulate the retina and visual cortex, and related connective peripheral circuits that replicate connectomics between the retina and visual cortex. This hardware experimentally displays advanced multi-functions of red-green color-blindness processing, low-power shape recognition, and self-driven motion tracking, promoting the development of machine vision, driverless technology, brain-computer interfaces, and intelligent robotics.

Photo-production of dissolved inorganic carbon from dissolved organic matter in contrasting coastal waters in the southwestern Taiwan Strait, China.

Photo-production of dissolved inorganic carbon (DIC) from chromophoric dissolved organic matter (CDOM) is an important transformation process in marine carbon cycle, but little is known about this process in Chinese coastal systems. This study investigated an estuarine water sample and a coastal seawater sample from the subtropical waters in southeast of China. Water samples were exposed to natural sunlight and the absorption and fluorescence of CDOM as well as the DIC concentration were measured in the summer of 2009. The estuarine water had higher CDOM level, molecular weight and proportion of humic-like fluorescent components than the seawater that exhibited abundant tryptophan-like fluorescent component. After a 3-day irradiation, the CDOM level decreased by 45% in the estuarine water and 20% in the seawater, accompanied with a decrease in the molecular weight and aromaticity of DOM which was inferred from an increase in the absorption spectral slope parameter. The photo-degradation rates of all the five fluorescent components were also notable, in particular two humic-like components (C4 and C5) were removed by 78% and 69% in the estuarine water and by 69% and 56% in the seawater. The estuarine water had a higher photo-production rate of DIC than the seawater (4.4 vs. 2.5 micromol/(L x day)), in part due to its higher CDOM abundance. The differences in CDOM compositions between the two types of waters might be responsible for the higher susceptibility of the estuarine water to photo-degradation and hence could also affect the photo-production process of DIC.

Design of Sb2Te3 nanoblades serialized by Te nanowires for a low-temperature near-infrared photodetector.

The dangling bond on the surface of bulk materials makes it difficult for a physically contacted heterojunction to form an ideal contact. Thus, periodic epitaxial junctions based on Sb2Te3 nanoblades serialized by Te nanowires (Sb2Te3/Te) were fabricated using a one-step hydrothermal epitaxial growth method. X-ray diffraction and electron microscopy reveal that the as-prepared product has a good crystal shape and heterojunction construction, which are beneficial for a fast photoresponse due to the efficient separation of photogenerated carriers. When the Sb2Te3/Te composite is denoted as a photodetector, it shows superior light response performance. Electrical analysis showed that the photocurrent of the as-fabricated device declined with temperatures rising from 10K to 300K at 980 nm. The responsivity and detectivity were 9.5 × 1011 µA W-1 and 1.22 × 1011 Jones at 50 K, respectively, which shows better detection performance than those of other Te-based photodetector devices. Results suggest that the as-constructed near-infrared photodetector may exhibit prospective application in low-temperature photodetector devices.

Pyro-phototronic effect enhanced broadband photodetection based on CdS nanorod arrays by magnetron sputtering.

In this work, self-powered photodetectors (PDs) based on RF magnetron sputtering-fabricated CdS nanorod arrays and polished Si substrates were prepared for the first time. By introducing the pyro-phototronic effect of wurtzite CdS, the self-powered PDs exhibit a broadband response range from UV (365 nm) to IR (1310 nm) at zero bias, even beyond the bandgap limit of the material. Both the photoresponsivity and specific detectivity are also enhanced by 23.3 times compared with those only based on the photovoltaic effect. In addition, the rise and fall times of self-powered PDs are 70 µs and 90 µs under 980 nm laser illumination. This research not only expands the application of CdS nanostructures in the field of pyro-phototronics, but also greatly enriches the preparation methods of CdS based pyro-phototronics materials.

An investigation of the effects of ZnO inverse opal pore size in the composite of ZnO nanorods/ZnO inverse opal on the performance of quantum dot-sensitized solar cells.

A semiconductor oxide composite consisting of ZnO nanorods (NRs) and ZnO inverse opal (IO) was fabricated and used in the photoanode of quantum dot-sensitized solar cells (QDSSCs). Using polystyrene spheres 500, 800, 1000, and 1500 nm in diameter as the IO template, ZnO composites and corresponding QDSSCs with ZnO IOs of different pore sizes were fabricated. The oxide composite prepared with ZnO IOs of different pore sizes showed similar micro-morphologies; however, the photovoltaic performance of the QDSSCs based on these composites varied greatly. The QDSSCs based on the ZnO composite achieved high power conversion efficiencies (PCEs) of more than 6%, and the maximum PCE was 7.26% when the ZnO IO pore diameter in the composite was 800 nm. This resulted in very high PCE values for the QDSSCs using CdS/CdSe quantum dot sensitizers. With further interface modifications of NH4F and ZnS, the QDSSC achieved an even higher PCE value of 11.38%. Subsequently, the effects of ZnO IO pore size in the composite on QDSSC performance were investigated.

Genetic diversity of Chinese rabies viruses: evidence for the presence of two distinct clades in China.

There have been three major rabies epidemics in China since the 1950s. To gain more insights into the molecular epidemiology of rabies viruses (RVs) for the third (the current) epidemic, we isolated RV from dogs and humans in major endemic areas, and characterized these isolates genetically by sequencing the entire glycoprotein (G) gene and the G-L non-coding region. These sequences were also compared phylogenetically with RVs isolated in China during previous epidemics and those around the world. Comparison of the entire G genes among the Chinese isolates revealed up to 21.8% divergence at the nucleotide level and 17.8% at the amino acid level. The available Chinese isolates could be divided into two distinct clades, each of which could be further divided into six lineages. Viruses in clade I include most of the Chinese viruses as well as viruses from southeast Asian countries including Indonesia, Malaysia, the Philippines, Thailand, and Vietnam. The viruses in the other clade were found infrequently in China, but are closely related to viruses distributed worldwide among terrestrial animals. Interestingly, most of the viruses isolated during the past 10 years belong to lineage A viruses within clade I whereas most of the viruses isolated before 1996 belong to other lineages within clades I and II. Our results indicated that lineages A viruses have been predominant during the past 10 years and thus are largely responsible for the third and the current epidemic in China. Our results also suggested that the Chinese RV isolates in clade I share a common recent ancestor with those circulating in southeast Asia.

Increased power conversion efficiency of dye-sensitized solar cells with counter electrodes based on carbon materials.

The good catalytic activity, resistance to iodine corrosion, and stability of carbon materials make them ideally suited for the fabrication of counter electrodes used in dye-sensitized solar cells (DSSCs). Different carbon materials have been used to make counter electrodes, and each has its own advantages, such as good film formation or high electric conductivity. Herein, various carbon materials were mixed and employed for preparing counter electrodes in DSSCs. Both fine film morphology and improved charge-carrier transport were obtained, and the power conversion efficiency of the DSSCs was thus increased. Accordingly, a cell efficiency of 6.29% was obtained by the DSSC with a counter electrode composed of the optimum mixture of carbon nanotubes, graphite, conductive carbon black, and graphene. Furthermore, DSSCs with a flexible counter electrode were fabricated using the optimum carbon material mixture, and the corresponding DSSCs achieved a power conversion efficiency of 4.32%.

A digital memories based user authentication scheme with privacy preservation.

The traditional username/password or PIN based authentication scheme, which still remains the most popular form of authentication, has been proved insecure, unmemorable and vulnerable to guessing, dictionary attack, key-logger, shoulder-surfing and social engineering. Based on this, a large number of new alternative methods have recently been proposed. However, most of them rely on users being able to accurately recall complex and unmemorable information or using extra hardware (such as a USB Key), which makes authentication more difficult and confusing. In this paper, we propose a Digital Memories based user authentication scheme adopting homomorphic encryption and a public key encryption design which can protect users' privacy effectively, prevent tracking and provide multi-level security in an Internet & IoT environment. Also, we prove the superior reliability and security of our scheme compared to other schemes and present a performance analysis and promising evaluation results.

Comparing the Bbs10 complete knockout phenotype with a specific renal epithelial knockout one highlights the link between renal defects and systemic inactivation in mice.

BACKGROUND: Bardet-Biedl Syndrome (BBS) is a genetically heterogeneous ciliopathy with clinical cardinal features including retinal degeneration, obesity and renal dysfunction. To date, 20 BBS genes have been identified with BBS10 being a major BBS gene found to be mutated in almost 20 percent of all BBS patients worldwide. It codes for the BBS10 protein which forms part of a chaperone complex localized at the basal body of the primary cilium. Renal dysfunction in BBS patients is one of the major causes of morbidity in human patients and is associated initially with urinary concentration defects related to water reabsorption impairment in renal epithelial cells. The aim of this study was to study and compare the impact of a total Bbs10 inactivation (Bbs10 (-/-)) with that of a specific renal epithelial cells inactivation (Bbs10  (fl/fl) ; Cdh16-Cre (+/-)). RESULTS: We generated the Bbs10 (-/-) and Bbs10  (fl/fl) ; Cadh16-Cre (+/-) mouse model and characterized them. Bbs10 (-/-) mice developed obesity, retinal degeneration, structural defects in the glomeruli, polyuria associated with high circulating arginine vasopressin (AVP) concentrations, and vacuolated, yet ciliated, renal epithelial cells. On the other hand, the Bbs10  (fl/fl) ; Cadh16-Cre (+/-)mice displayed no detectable impairment. CONCLUSIONS: These data highlight the importance of a systemic Bbs10 inactivation to trigger averted renal dysfunction whereas a targeted absence of BBS10 in the renal epithelium is seemingly non-deleterious.