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Miniaturized spectrometers are of considerable interest for their portability. Most designs to date employ a photodetector array with distinct spectral responses or require elaborated integration of micro & nano optic modules, typically with a centimeter-scale footprint. Here, we report a design of a micron-sized near-infrared ultra-miniaturized spectrometer based on two-dimensional van der Waals heterostructure (2D-vdWH). By introducing heavy metal atoms with delocalized electronic orbitals between 2D-vdWHs, we greatly enhance the interlayer coupling and realize electrically tunable infrared photoresponse (1.15 to 1.47 μm). Combining the gate-tunable photoresponse and regression algorithm, we achieve spectral reconstruction and spectral imaging in a device with an active footprint < 10 μm. Considering the ultra-small footprint and simple fabrication process, the 2D-vdWHs with designable bandgap energy and enhanced photoresponse offer an attractive solution for on-chip infrared spectroscopy.

Self-powered photodetectors with broadband and polarization-sensitive photoresponse are desirable for many important applications such as wearable electronic devices and wireless communication systems. Recently, two-dimensional (2D) materials have been demonstrated as promising candidates for self-powered photodetectors owing to their advantages in light–matter interaction, transport, electronic properties, and so on. However, their performance in speed, broadband response, and multifunction is still limited. Here, we report a PdSe2 photodetector with asymmetric van der Waals (vdWs) contacts formed by using a homojunction configuration. This device achieves a high responsivity approaching 53 mA/W, a rise/decay time of about 0.72 ms/0.24 ms, and a detectivity of more than 5.17 × 1011 Jones in the visible-near infrared regime (532–1470 nm). In addition, a linear polarization-sensitive response can be observed with an anisotropy ratio of 1.11 at 532 nm and 1.62 at 1064 nm. Furthermore, a strong anisotropic response endows this photodetector with outstanding polarization imaging capabilities, realizing a contrast-enhanced degree of linear polarization imaging. Our proposed device architecture demonstrated the great potential of PdSe2-based asymmetric vdWs contacts for high-performance photodetectors operating without any external bias.

Graphs play a key role in data analytics. Graphs and the software systems used to work with them are highly diverse. Algorithms interact with hardware in different ways and which graph solution works best on a given platform changes with the structure of the graph. This makes it difficult to decide which graph programming framework is the best for a given situation. In this paper, we try to make sense of this diverse landscape. We evaluate five different frameworks for graph analytics: SuiteS-parse GraphBLAS, Galois, the NWGraph library, the Graph Kernel Collection, and GraphIt. We use the GAP Benchmark Suite to evaluate each framework. GAP consists of 30 tests: six graph algorithms (breadth-first search, single-source shortest path, PageRank, betweenness centrality, connected components, and triangle counting) on five graphs. The GAP Benchmark Suite includes high-performance reference implementations to provide a performance baseline for comparison. Our results show the relative strengths of each framework, but also serve as a case study for the challenges of establishing objective measures for comparing graph frameworks.

Finding connected components is one of the most widely used operations on a graph. Optimal serial algorithms for the problem have been known for half a century, and many competing parallel algorithms have been proposed over the last several decades under various different models of parallel computation. This paper presents a class of parallel connected-component algorithms designed using linear-algebraic primitives. These algorithms are based on a PRAM algorithm by Shiloach and Vishkin and can be designed using standard GraphBLAS operations. We demonstrate two algorithms of this class, one named LACC for Linear Algebraic Connected Components, and the other named FastSV which can be regarded as LACC's simplification. With the support of the highly-scalable Combinatorial BLAS library, LACC and FastSV outperform the previous state-of-the-art algorithm by a factor of up to 12x for small to medium scale graphs. For large graphs with more than 50B edges, LACC and FastSV scale to 4K nodes (262K cores) of a Cray XC40 supercomputer and outperform previous algorithms by a significant margin. This remarkable performance is accomplished by (1) exploiting sparsity that was not present in the original PRAM algorithm formulation, (2) using high-performance primitives of Combinatorial BLAS, and (3) identifying hot spots and optimizing them away by exploiting algorithmic insights.

High-definition near-eye display technology has extremely close sight distance, placing a higher demand on the size, performance, and array of light-emitting pixel devices. Based on the excellent photoelectric performance of metal halide perovskite materials, perovskite light-emitting diodes (PeLEDs) have high photoelectric conversion efficiency, adjustable emission spectra, and excellent charge transfer characteristics, demonstrating great prospects as next-generation light sources. Despite their potential, the solubility of perovskite in photoresist presents a hurdle for conventional micro/nano processing techniques, resulting in device sizes typically exceeding 50 μm. This limitation impedes the further downsizing of perovskite-based components. Herein, we propose a plane-structured PeLED device that can achieve microscale light-emitting diodes with a single pixel device size < 2 μm and a luminescence lifetime of approximately 3 s. This is accomplished by fabricating a patterned substrate and regulating ion distribution in the perovskite through self-doping effects to form a PN junction. This breakthrough overcomes the technical challenge of perovskite–photoresist incompatibility, which has hindered the development of perovskite materials in micro/nano optoelectronic devices. The strides made in this study open up promising avenues for the advancement of PeLEDs within the realm of micro/nano optoelectronic devices. [ABSTRACT FROM AUTHOR]

Simple Summary: Classical swine fever is a highly contagious disease that severely affects the swine industry worldwide. The clinical symptoms of infected pigs are unusually complex, making it difficult to distinguish between wild-type and vaccinated pigs. In this study, a dual TaqMan-MGB RT-qPCR method for the identification of wild-type CSFV and attenuated vaccine strains was established. This newly developed method could specifically detect CSFV and HCLV with no cross-reactivity with other swine pathogens. The detection limit for the NS3 gene of CSFV and HCLV was 1.67 × 101 copies/μL, respectively. For precision testing, the repeatability and reproducibility of the relative standard deviation was less than 2%. This method was successfully used for rapid detection of 193 real samples. This dual TaqMan-MGB RT-qPCR technology meets the needs for early and rapid detection of CSFV, and can provide an efficient and rapid detection method for the investigation and analysis of CSFV field strain infections and vaccine immune status, thereby laying the foundation for better prevention and control of the occurrence and spread of CSF. To establish a rapid real-time RT-PCR method for differentiating wild-type classical swine fever virus (CSFV) strains from vaccine strains (HCLV), we designed a universal primer targeting the NS3 gene to detect wild-type CSFV strains and vaccine strains simultaneously, and two TaqMan-MGB probes were designed to differentiate between wild-type and vaccine strains. After optimizing the RT-qPCR conditions, a rapid dual TaqMan-MGB RT-qPCR method for the detection and identification of CSFV and HCLV was developed. The results showed that method could specifically detect CSFV and HCLV with no cross-reactivity with other swine pathogens. The analytic sensitivity for the NS3 gene of CSFV and HCLV were 1.67 × 101 copies/μL, respectively. For precision testing, the repeatability and reproducibility of the test was less than 2%. This method was successfully used for the rapid detection of 193 biological samples collected from CSFV-vaccinated pigs. This fast and accurate detection technology can be used for the detection of CSFV and is suitable for differentiating between wild-type CSFV strains and vaccine strains. [ABSTRACT FROM AUTHOR]

Two-dimensional materials with high anisotropic optical properties and high exciton binding energy offer great advantages for developing nanostructure electronic and optoelectronic devices. However, conduction electron scattering from surface defects caused by the short width and length of the channel layer in semiconductor devices blocks their application. In this research, NaP15 is considered as another kind of layered material with high anisotropic properties. Its anisotropic layered structure was revealed by its detailed crystal structure and electron-density distribution calculation, which showed two antiparallel rows of pentagonal P tubes interacting with weak Coulomb forces and four adjacent P tubes in one unit coordinated by Na atoms. The outstanding chemical stability, angle-resolved polarized and temperature-dependent Raman spectroscopy, and neutral exciton emission caused by surface state excitation in exfoliated NaP15 nanoribbons at room temperature clearly reveal its one-dimensional layered property. The distinctive structural characteristics and electronic properties render it with substantial potential for applications in the realm of polarimetric detectors. [ABSTRACT FROM AUTHOR]

Improving power conversion efficiency (PCE) in photovoltaics has driven innovative approaches in solar cell design and technology. Silicon heterojunction (SHJ) solar cells exhibit advantages in PCE due to their effective passivating contact structures. SHJ–interdigitated back contact (SHJ–IBC) solar cells have the potential to surpass traditional SHJ cells, attributed to their advantage in short‐circuit current (JSC). Herein, Silvaco Atlas technology computer‐aided design is used to create digital twins of high‐efficiency SHJ solar cells with amorphous silicon and nanocrystalline silicon hole selective contact (HSC) layers. Using parameters from digital twins of SHJ solar cells, the practical efficiency limit of SHJ–IBC solar cells is assessed. The results show that SHJ–IBC cells can achieve potential efficiencies of 27.01% with amorphous HSC and 27.38% with nanocrystalline HSC. Further efficiency augmentation to 27.51% can be achieved by narrowing the gap from 80 to 20 μm. This study not only advances comprehension of SHJ–IBC solar cells but also provides insights into optimizing geometrical configurations for improved performance. The utilization of digital twins provides a valuable tool for predicting and evaluating the performance of SHJ–IBC solar cells, contributing substantively to the ongoing development of high‐efficiency photovoltaic technology. [ABSTRACT FROM AUTHOR]