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Blockchain systems enable new applications, such as cryptocurrencies and smart contracts, using decentralized consensus without trusted authorities. A number of blockchain systems based on proof-of-stake techniques have been proposed, many of which use verifiable random functions (VRFs) as fundamental building blocks, such as Ouroboros, Algorand, and Dfinity, etc. The secret key of a VRF scheme is critical to the security of a VRF and the entire blockchain system built on it. To protect the secret keys of VRFs and maintain the efficiency of the proof-of-stake protocol, we extend the objective of cryptographic program obfuscation to VRFs and propose an obfuscatable VRF scheme. In particular, we propose an obfuscator that can transform the implementation of the scheme's random string generation algorithm and the given secret key into an unintelligible form. Obfuscated implementations of the random string generation algorithm are deployed on peers of a blockchain for supporting normal routines of the proof-of-stake protocol. Even if a hacker has controlled a peer's host, the owner's secret key will not be compromised because the key has been hardwired into the obfuscated implementation in an “encrypted manner”. We formally prove the correctness and the security of the proposed VRF and obfuscator. Since the proposed scheme supports the general semantics of verifiable random functions, it can be used as a building block for all blockchain systems that adopt proof-of-stake protocols based on VRFs. The experimental result indicated that the scheme performs well on various platforms, such as cloud servers, workstations, smartphones, and embedded devices.

It has been suggested that the function of sleep is to actively clear metabolites and toxins from the brain. Enhanced clearance is also said to occur during anesthesia. Here, we measure clearance and movement of fluorescent molecules in the brains of male mice and show that movement is, in fact, independent of sleep and wake or anesthesia. Moreover, we show that brain clearance is markedly reduced, not increased, during sleep and anesthesia.

SnO2is widely used as the electron transport layer (ETL) in n–i–p perovskite solar cells. However, the deep-level defects at the interface between SnO2and the perovskite film will lead to energy loss, reducing the open-circuit voltage. Therefore, the interface optimization is essential to raise the efficiency and enhance the stability of perovskite solar cells. In this work, we introduce NH4F into the SnO2electron transport layers, and the optimized SnO2films reduce the interface defect density, improve the charge extraction, and reveal a better energy-level arrangement. Compared to the conventional SnO2perovskite solar cell, the average Vocis improved by 70 mV with the champion efficiency up to 22.12%. Moreover, the unencapsulated F-doped SnO2perovskite solar cells show better thermal stability (maintained 86.2%) and humidity stability (maintained 80.8%) after 35 days.

The detection of broadband spectroscopy is a huge challenge for modern optoelectronics, especially for extremely high- or low-energy photons. For metal halide perovskites significant progress has been made in high-energy photons such as X-rays, but there is little exploration of the perovskites in the high-performance detection of low-energy photons, especially mid- or far-infrared photons. Most infrared photodetectors suffer large dark currents, and perovskite photodetectors’ performances are significantly limited by ion migration. Here, a facile solution evaporation method is developed to grow a centimeter-scale zero-dimensional (0D), lead-free perovskite Cs3Bi2I9single crystal for high-performance mid-infrared photodetectors with ultralow dark current drifts. The 0D Cs3Bi2I9perovskite single crystal (PSC) photodetector shows an ultralow dark current drift (1.67 × 10–17A cm–2V–1s–1, 9 orders of magnitude smaller than that of MAPbI3) and ultralow power consumption (smaller than 1 pA at 1 V bias) for greatly inhibited ion migration. The photodetector achieves effective photodetection from the ultraviolet to the mid-infrared (from 343 to 4000 nm) at room temperature based on the photoelectric and photobolometric effects with the best responsivity of 3.15 mA/W and detectivity of 8.7 × 108jones at the wavelength of 343 nm at 0.033 mW/cm2. This work opens a door for low-dimensional perovskite-based mid-infrared detectors and provides a new path for the development of infrared perovskite photonics.

ABSTRACTTreatment of central nervous system (CNS) demyelination is greatly hindered by lack of the knowledge regarding to underlying molecular mechanisms as well as therapeutic agents. Here, we report a novel small molecule agent, gastrodin (GAS), which can significantly promote CNS myelination in in vivomice models. By using high-throughput sequencing analysis, we discover a key long non-coding RNA Gm7237 that can enhance CNS myelination and is up-regulated by GAS. Through using bioinformatic analysis and experimental validations, we further unravel that microRNA-142a (miR-142a) and its target myelin gene regulatory factor (MRF) is under the direct regulation by Gm7237. Finally, we demonstrate that Gm7237/miR-142a/MRF axis is the key pathway involved in CNS myelination mediated by GAS. Overall, our results provide not only a novel agent for therapeutic treatment of CNS demyelination but also a molecular basis responsible for GAS-promoted CNS myelination.

Purpose: The purpose of this paper is to investigate the impact of employer-provided health benefits (EPHBs) on labor supply decisions of documented and undocumented farm workers. By establishing a significant linkage between EPHB and farm work decisions, this study provides important implications for farm employment retention and the financial sustainability of farm businesses. Design/methodology/approach: Using data from the National Agricultural Workers Survey, objective (actual) and subjective (expected) employment data are used as outcome variables analyzed under an ordered probit model, with the data pre-processed using the coarsened exact matching method to reduce endogeneity issues within the estimation. Findings: Results confirm the influence of EPHB on farm workers’ decisions to remain employed on the farm as well as on the duration of their farm employment. Comparatively, EPHB significantly influences undocumented farm workers’ decisions on actual employment duration and subjective working expectations while documented workers seem to ascribe less importance to EPHB in their farm employment decisions. Practical implications: This study provides important financial and business viability implications as the value of farm labor services retained through EPHB can translate to high opportunity losses, if ineffective. Alternative labor-saving strategies, such as mechanization, can only potentially lead to serious financial challenges for agribusiness firms, especially small-scale farm operations. This study emphasizes the need for more effective employment retention incentives for the sake of sustaining farm business viability. Originality/value: This study presents empirical evidence on the important influence of EPHB on farm employment decisions, especially those made by undocumented farm workers, that have not been extensively explored in literature.

This article investigates the time allocation choices of US workers between farm work and other job alternatives. Results indicate that green card farm workers tend to allocate fewer workweeks to farm employment than citizens and undocumented workers, in favour of better opportunities in the non-farm sector. There is evidence of an assimilation effect, whereby undocumented workers also tend to re-allocate their time from farm to non-farm employment as their residence tenure increases, even though they experience constrained mobility and visibility during periods of strict immigration control. In the context of employers’ violations of the existing labour laws that currently protect even the rights of undocumented workers, such turnover decisions seem justified. The findings raise concerns about whether any governmental effort to legalise the immigration status of such workers would reduce farm job turnover rates and increase farm employment retention, so long as labour standards are not enforced. Moreover, external economic shocks could more easily induce citizen and green card farm workers to abandon farm employment, whereas undocumented workers tend to remain in their farm jobs during such difficult times.

Using monthly data from January 1998 to May 2021, this study investigates the asymmetric impact of global economic policy uncertainty (GEPU) on international grain prices by using nonlinear autoregressive distribution lag (NARDL). We find that there is a positive, asymmetric relationship between GEPU and international grain prices. Specifically, GEPU has a greater negative than positive impact on wheat and maize prices, and the positive impact on soybean price is more pronounced than the negative one. We have also observed that the asymmetric impact of GEPU on rice price is not significant in the long run. The findings have important implications to formulate targeted and differentiated international grain price regulatory policies.

The fabrication of α-FAPbI3perovskite films usually requires high temperature annealing above 150 °C, and the residual tensile strain in the films seriously affects the stability of α-FAPbI3by converting to δ-phase FAPbI3. Here, we use MASCN surface treatment of FAPbI3films to induce a rotation of the coplanar octahedron [PbI6]4-to the metric octahedron for the strong interaction of SCN–with Pb2+, converting δ-FAPbI3into α-FAPbI3highly crystalline films at room temperature. The optimized FAPbI3films have high stability due to releasing residual tensile strains after MASCN treatment. The efficiency of the MASCN-treated unannealed FAPbI3PSC is 19.03%, while the optimized FAPbI3annealed at 100 °C shows a maximum PCE of 21.95% on a small area. The solar cell stability for humidity, light, and thermal stability are significantly improved. The MASCN treated FAPbI3achieves a PCE of 15.32% on a PSC module with an effective area of 9.6 cm2and maintains an initial efficiency of 94.1% after 100 days of ageing at 85 °C and 85% humidity.