Hitchhiking of Cas9 with nucleus-localized proteins impairs its controllability and leads to efficient genome editing of NLS-free Cas9.

CRISPR-Cas9 is the most commonly used genome-editing tool in eukaryotic cells. To modulate Cas9 entry into the nucleus to enable control of genome editing, we constructed a light-controlled CRISPR-Cas9 system to control exposure of the Cas9 protein nuclear localization signal (NLS). Although blue-light irradiation was found to effectively control the entry of Cas9 protein into the nucleus with confocal microscopy observation, effective gene editing occurred in controls with next-generation sequencing analysis. To further clarify this phenomenon, a CRISPR-Cas9 editing system without the NLS and a CRISPR-Cas9 editing system containing a nuclear export signal were also constructed. Interestingly, both Cas9 proteins could achieve effective editing of target sites with significantly reduced off-target effects. Thus, we speculated that other factors might mediate Cas9 entry into the nucleus. However, NLS-free Cas9 was found to produce effective target gene editing even following inhibition of cell mitosis to prevent nuclear import caused by nuclear membrane disassembly. Furthermore, multiple nucleus-localized proteins were found to interact with Cas9, which could mediate the "hitchhiking" of NLS-free Cas9 into the nucleus. These findings will inform future attempts to construct controllable gene-editing systems and provide new insights into the evolution of the nucleus and compatible protein functions.

Copper Modulated Lead-Free Cs4 MnSb2 Cl12 Double Perovskite Microcrystals for Photocatalytic Reduction of CO2.

In order to deal with the global energy crisis and environmental problems, reducing carbon dioxide through artificial photosynthesis has become a hot topic. Lead halide perovskite is attracted people's attention because of its excellent photoelectric properties, but the toxicity and long-term instability prompt people to search for new photocatalysts. Herein, a series of <111> inorganic double perovskites Cs4 Mn1-x Cux Sb2 Cl12 microcrystals (x = 0, 0.1, 0.2, 0.3, 0.4, and 0.5) are synthesized and characterized. Among them, Cs4 Mn0.7 Cu0.3 Sb2 Cl12 microcrystals have the best photocatalytic performance, and the yields of CO and CH4 are 503.86 and 68.35 µmol g-1 , respectively, after 3 h irradiation, which are the highest among pure phase perovskites reported so far. In addition, in situ Fourier transform infrared (FT-IR) spectroscopy and electron spin resonance (ESR) spectroscopy are used to explore the mechanism of the photocatalytic reaction. The results highlight the potential of this class of materials for photocatalytic reduction reactions.

Novelty All-Inorganic Titanium-Based Halide Perovskite for Highly Efficient Photocatalytic CO2 Conversion.

Lead halide perovskite materials have great potential for photocatalytic reaction due to their low fabrication cost, unique optical absorption coefficient, and suitable band structures. However, the main problems are the toxicity and instability of the lead halide perovskite materials. Therefore, a facile synthetic method is used to prepare lead-free environmentally friendly Cs2 TiX6 (X = Cl, Cl0.5 Br0.5 , Br) perovskite materials. Their structural and optical characteristics are systematically investigated. The band gaps of the produced samples are illustrated to be from 1.87 to 2.73 eV. Moreover, these materials can keep high stability in harsh environments such as illumination and heating, and the Cs2 Ti(Cl0.5 Br0.5 )6 microcrystals demonstrate the yields of 176 µmol g-1 for CO and 78.9 µmol g-1 for CH4 after light irradiation for 3 h, which is of the first report of Ti-based perovskite photocatalysts. This finding demonstrates that the Ti-based perovskites will create opportunities for photocatalytic applications, which may offer a new idea to construct low-cost, eco-friendly, and bio-friendly photocatalysts.

Advances in Off-Target Detection for CRISPR-Based Genome Editing.

The CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)-based genome editing system exhibits marked potential for both gene editing and gene therapy, and its continuous improvement contributes to its great clinical potential. However, the largest hindrance to its application in clinical practice is the presence of off-target effects (OTEs). Thus, in addition to continuous optimization of the CRISPR system to reduce and eventually eliminate OTEs, further development of unbiased genome-wide detection of OTEs is key for its successful clinical application. This article summarizes detection strategies for OTEs of different CRISPR systems, to provide detailed guidance for the detection of OTEs in CRISPR-based genome editing.

Solidification/stabilization of heavy metals and its efficiency in lead-zinc tailings using different chemical agents.

Lead-zinc tailings are generated during the mining process which is considered as hazardous solid waste due to its high heavy metal content and leachability in the natural state. At present, the most effective technology for disposing heavy metals in solid wastes is the solidification/stabilization (S/S) technique. In terms of S/S technology, chemical stabilization is one of the most potential and practical method. This paper aims to investigate the S/S property of four typical chemical agents (Na2S, NaH2PO4, TMT and Na2EDTA) on the heavy metals in lead-zinc tailings. The results reveal that the heavy metals lead and zinc in tailings are stabilized more effectively by using chelating agents TMT than by using inorganic chemical agents Na2S and NaH2PO4. When the dosage of TMT reaches 4%, the leaching concentration of lead and zinc is 0.18 and 14.60 mg/L according to toxicity characteristic leaching procedure (TCLP), and the stabilization efficiency of lead and zinc is 99.31% and 80.92%, respectively, while the leaching concentration of lead and zinc just drops to 0.41 and 16.00 mg/L with addition of 10% NaH2PO4. Furthermore, the leaching concentration of heavy metal lead in tailings treated by 4% Na2EDTA increases to 53.44 mg/L which far exceeds the standard of pollution control. Therefore, considering stabilization efficiency and dosage, TMT is the preferred agent for solidifying heavy metals in lead-zinc tailings.

Strategies for Optimization of the Clustered Regularly Interspaced Short Palindromic Repeat-Based Genome Editing System for Enhanced Editing Specificity.

The clustered regularly interspaced short palindromic repeats (CRISPR) system is inarguably the most valuable gene editing tool ever discovered. Currently, three classes of CRISPR-based genome editing systems have been developed for gene editing, including CRISPR/CRISPR associate system (Cas) nucleases, base editors, and prime editors. Ever-evolving CRISPR technology plays an important role in medicine; however, the biggest obstacle to its use in clinical practice is the induction of off-target effects (OTEs) during targeted editing. Therefore, continuous improvement and optimization of the CRISPR system for reduction of OTEs is a major focus in the field of CRISPR research. This review aims to provide a comprehensive guide for optimization of the CRISPR-based genome editing system.

Impact of Hydroiodic Acid on Resistive Switching Performance of Lead-Free Cs3Cu2I5 Perovskite Memory.

Herein, we employed lead-free Cs3Cu2I5 perovskite films as the functional layers to construct Al/Cs3Cu2I5/ITO memory devices and systematically investigated the impact on the corresponding resistive switching (RS) performance via adding different amounts of hydroiodic acid (HI) in Cs3Cu2I5 precursor solution. The results demonstrated that the crystallinity and morphology of the Cs3Cu2I5 films can be improved and the resistive switching performance can be modulated by adding an appropriate amount of HI. The obtained Cs3Cu2I5 films by adding 5 µL HI exhibit the fewest lattice defects and flattest surface (RMS = 13.3 nm). Besides, the memory device, utilizing the optimized films, has a low electroforming voltage (1.44 V), a large on/off ratio (∼65), and a long retention time (104 s). The RS performance impacted by adding HI, providing a scientific strategy for improving the RS performance of iodine halide perovskite-based memories.

Utilization of Carbide Slag by Wet Grinding as an Accelerator in Calcium Sulfoaluminate Cement.

In this study, wet-ground carbide slag (i.e., WGCS) was utilized as an accelerator in calcium sulfoaluminate cement (CSA) for obtaining considerably faster setting processes for some special engineering processes such as plugging projects and rapid repair engineering. The WGCS-CSA system was designed, in which the replacement ratio of CSA by carbide slag was chosen as 4%, 8% and 12%. The setting time and compressive strength were measured, and the mechanism of the system hydration was studied in detail by means of calorimetry, XRD, thermogravimetry (TG) and SEM. The results showed that WGCS shortened the setting time of cement and significantly augmented the early strength. The addition of 8% of WGCS contributed to increasing the 2-h compressive strength from 4.2 MPa to 32.9 MPa. The decrease in the setting time and the increase in the initial strength were mainly attributed to the high initial pH value of the liquid phase and the high content of calcium ions in WGCS. Both these factors contributed to the ettringite formation and, at the same time, to the transformation of the morphology at a later time. Such results testify that WGCS can be used as an accelerator in the CSA system and also that it provides a novel approach to the reutilization of carbide slag.

Effect of TIPA on mechanical properties and hydration properties of cement-lithium slag system.

Effect of triisopropanolamine (TIPA) on compressive strength and hydration properties of cement-lithium slag (LS, 30%) paste was studied. The results demonstrated that the addition of TIPA is advantageous for compressive strength at 7 d, 28 d and 60 d. The reason was related to the pore complexity and hydration process of cement and LS. TIPA reduced the total porosity, and increased the fractal dimension, making the pore structure more complicated. In addition, TIPA promoted the pozzolanic reaction of LS and the hydration of cement, expediting the formation of C-S(A)-H gel. TIPA accelerated the dissolution of aluminate ions, silicate ions and ferric ions in the pore solution, thereby accelerating the pozzolanic reaction of LS. During the hydration of cement-LS paste, TIPA facilitated the conversion of ettringite to the AFm-like phase and produced more C-A-S-H gel by promoting the dissolution of aluminate ions.

High-Performance Deep Ultraviolet Photodetector Based on a One-Dimensional Lead-Free Halide Perovskite CsCu2I3 Film with High Stability.

Lead halide perovskites have received much attention in the field of optoelectronic devices. However, the environment-unfriendly nature and intrinsic instability of these perovskites hamper their commercial applications. In this work, one novel one-dimensional lead-free halide perovskite with high stability, CsCu2I3, was prepared via an antisolvent-assisted crystallization method. The prepared CsCu2I3 bears a high exciton binding energy of ∼105 meV and a high photoluminescence quantum yield of 12.3%. We fabricated a deep ultraviolet photodetector based on a CsCu2I3 film that is nearly blind to 405 nm visible light but is sensitive to 265 and 365 nm illumination. The device exhibits excellent reproducibility and a high Ilight/Idark ratio of 22 under 265 nm illumination. Furthermore, the responsivity, specific detectivity, and external quantum efficiency are as high as 22.1 mA/W, 1.2 × 1011 Jones, and 10.3% under a light density of 0.305 mW/cm2, respectively. These findings demonstrate that CsCu2I3 perovskites should have great potential for future optoelectronics.

Analysis of melting reconstruction treatment and cement solidification on ultra-risk municipal solid waste incinerator fly ash-blast furnace slag mixtures.

High temperature melting treatment and cement solidification are technologies currently used to reduce the leaching of heavy metals in municipal solid waste incinerator (MSWI) fly ash. In this paper, to ascertain the feasibility of melting MSWI fly ash with blast furnace (BF) slag, ultra-risk MSWI(U-MSWI) fly ash having high heavy metal (Zn, Pb, Cu, and Cr) contents were blended with BF slag, then melted and quenched into water to prepare reconstructed slag. The melting and solidification behaviors, phase composition and microstructure, and heavy metal leachability of reconstructed slag were studied. In addition, to study the further solidification and utilization of reconstructed slag in cement, the compressive strength and leaching concentration of cement composites with reconstructed slag were also investigated. The results indicate that the presence of heavy metals in the U-MSWI fly ash had a little influence on the microstructure and phase composition of reconstructed slag. The leaching concentration of heavy metals in the reconstructed slag increased with the increasing of U-MSWI fly ash content, and when the content of U-MSWI fly ash was less than 50 wt%, the reconstructed slag could meet the environmental requirements. The reconstructed slag further solidified by cement could be applied to landfill and construction materials. The technology of melting reconstruction treatment with cement solidification was a technical-economical choice for the industrial treatment of U-MSWI fly ash.

Molecular Beam Epitaxy Scalable Growth of Wafer-Scale Continuous Semiconducting Monolayer MoTe2 on Inert Amorphous Dielectrics.

Monolayer MoTe2 , with the narrowest direct bandgap of ≈1.1 eV among Mo- and W-based transition metal dichalcogenides, has attracted increasing attention as a promising candidate for applications in novel near-infrared electronics and optoelectronics. Realizing 2D lateral growth is an essential prerequisite for uniform thickness and property control over the large scale, while it is not successful yet. Here, layer-by-layer growth of 2 in. wafer-scale continuous monolayer 2H-MoTe2 films on inert SiO2 dielectrics by molecular beam epitaxy is reported. A single-step Mo-flux controlled nucleation and growth process is developed to suppress island growth. Atomically flat 2H-MoTe2 with 100% monolayer coverage is successfully grown on inert 2 in. SiO2 /Si wafer, which exhibits highly uniform in-plane structural continuity and excellent phonon-limited carrier transport behavior. The dynamics-controlled growth recipe is also extended to fabricate continuous monolayer 2H-MoTe2 on atomic-layer-deposited Al2 O3 dielectric. With the breakthrough in growth of wafer-scale continuous 2H-MoTe2 monolayers on device compatible dielectrics, batch fabrication of high-mobility monolayer 2H-MoTe2 field-effect transistors and the three-level integration of vertically stacked monolayer 2H-MoTe2 transistor arrays for 3D circuitry are successfully demonstrated. This work provides novel insights into the scalable synthesis of monolayer 2H-MoTe2 films on universal substrates and paves the way for the ultimate miniaturization of electronics.