Lewis acid-promoted direct synthesis of isoxazole derivatives.

Isoxazole derivatives were synthesized via a one-pot method utilizing 2-methylquinoline derivatives as template substrates, sodium nitrite as a nitrogen-oxygen source, and solely using aluminum trichloride as the additive. This approach circumvents the need for costly or highly toxic transition metals and presents a novel pathway for the synthesis of isoxazole derivatives.

A Bifunctional CdS/MoO2 /MoS2 Catalyst Enhances Photocatalytic H2 Evolution and Pyruvic Acid Synthesis.

The best use of photogenerated electrons and holes is crucial to boosting photocatalytic activity. Herein, a bifunctional dual-cocatalyst-modified photocatalyst is constructed based on CdS/MoO2 /MoS2 hollow spheres for hydrogen evolution coupled with selective pyruvic acid (PA) production from lactic acid (LA) oxidation. MoS2 and MoO2 are simultaneously obtained from the conversion of CdMoO4 in one step. In a photocatalytic process, the MoS2 and MoO2 function as the reduction and oxidation centers on which photogenerated electrons and holes accumulate and are used for hydrogen evolution reaction (HER) and PA synthesis, respectively. By monitoring the intermediates, a two-step single-electron route for PA production is proposed, initiated by the cleavage of the α-C(sp3 )-H bond in the LA. The conversion of LA and the selectivity of PA can reach ca. 29 % and 95 % after a five-hour reaction, respectively.

General Synthesis of Lead-Free Metal Halide Perovskite Colloidal Nanocrystals in 1-Dodecanol.

Lead halide perovskite nanocrystals (NCs) exhibit great application potential in optoelectronic devices because of their tunable band gaps and facile colloidal synthesis, but they suffer from serious lead toxicity and instability. It is highly desirable to substitute lead with other elements to acquire nontoxic and environmentally friendly lead-free perovskite NCs for optoelectronic devices. Here, we report a general method for the colloidal synthesis of a series of bismuth/antimony-based halide perovskite NCs with various constituents and optical band gaps from 1.97 to 3.15 eV. In our proposed synthetic system, 1-dodecanol is adopted as the solvent instead of the conventionally used 1-octadecene to realize size controllability of bismuth/antimony-based metal halide perovskite NCs. It is found that 1-dodecanol can act as a surfactant to tightly adsorb on the surface of bismuth/antimony-based halide perovskite NCs, enabling their small sizes (∼2 nm) and high dispersibility. Simultaneously, the band gaps of bismuth/antimony-based halide (A3B2X9, where A = CH3NH3, Cs, or Rb, B = Bi or Sb, and X = Cl, Br, or I) perovskite NCs can be systematically tuned by the atomic substitution of A, B, or X lattice sites. Moreover, to show the optoelectronic application potential of these lead-free halide perovskite NCs, a solar cell based on colloidal Cs3Bi2I9 perovskite NCs is demonstrated. The developed colloidal synthesis of bismuth/antimony-based halide NCs in 1-dodecanol will offer an alternative route to fabricating lead-free halide perovskite optoelectronic devices.

Distinct loci in the CHRNA5/CHRNA3/CHRNB4 gene cluster are associated with onset of regular smoking.

Neuronal nicotinic acetylcholine receptor (nAChR) genes (CHRNA5/CHRNA3/CHRNB4) have been reproducibly associated with nicotine dependence, smoking behaviors, and lung cancer risk. Of the few reports that have focused on early smoking behaviors, association results have been mixed. This meta-analysis examines early smoking phenotypes and SNPs in the gene cluster to determine: (1) whether the most robust association signal in this region (rs16969968) for other smoking behaviors is also associated with early behaviors, and/or (2) if additional statistically independent signals are important in early smoking. We focused on two phenotypes: age of tobacco initiation (AOI) and age of first regular tobacco use (AOS). This study included 56,034 subjects (41 groups) spanning nine countries and evaluated five SNPs including rs1948, rs16969968, rs578776, rs588765, and rs684513. Each dataset was analyzed using a centrally generated script. Meta-analyses were conducted from summary statistics. AOS yielded significant associations with SNPs rs578776 (beta = 0.02, P = 0.004), rs1948 (beta = 0.023, P = 0.018), and rs684513 (beta = 0.032, P = 0.017), indicating protective effects. There were no significant associations for the AOI phenotype. Importantly, rs16969968, the most replicated signal in this region for nicotine dependence, cigarettes per day, and cotinine levels, was not associated with AOI (P = 0.59) or AOS (P = 0.92). These results provide important insight into the complexity of smoking behavior phenotypes, and suggest that association signals in the CHRNA5/A3/B4 gene cluster affecting early smoking behaviors may be different from those affecting the mature nicotine dependence phenotype.

Ultra-High Sensitivity Anisotropic Piezoelectric Sensors for Structural Health Monitoring and Robotic Perception.

Monitoring minuscule mechanical signals, both in magnitude and direction, is imperative in many application scenarios, e.g., structural health monitoring and robotic sensing systems. However, the piezoelectric sensor struggles to satisfy the requirements for directional recognition due to the limited piezoelectric coefficient matrix, and achieving sensitivity for detecting micrometer-scale deformations is also challenging. Herein, we develop a vector sensor composed of lead zirconate titanate-electronic grade glass fiber composite filaments with oriented arrangement, capable of detecting minute anisotropic deformations. The as-prepared vector sensor can identify the deformation directions even when subjected to an unprecedented nominal strain of 0.06%, thereby enabling its utility in accurately discerning the 5 µm-height wrinkles in thin films and in monitoring human pulse waves. The ultra-high sensitivity is attributed to the formation of porous ferroelectret and the efficient load transfer efficiency of continuous lead zirconate titanate phase. Additionally, when integrated with machine learning techniques, the sensor's capability to recognize multi-signals enables it to differentiate between 10 types of fine textures with 100% accuracy. The structural design in piezoelectric devices enables a more comprehensive perception of mechanical stimuli, offering a novel perspective for enhancing recognition accuracy.

Remote Functionalization of Inert C(sp3)-H Bonds via Dual Catalysis Driven by Alkene Hydrofluoroalkylation Using Industrial Feedstocks.

We have developed a dual-catalytic system capable of site-selective azidation of inert C(sp3)-H bonds with concomitant and modular anti-Markovnikov alkene fluoroalkylation. The protocol leverages the synergetic cooperation of both the photocatalyst and earth-abundant iron catalyst to deliver two radical species in succession to minimally functionalized alkenes. This powerful catalyst system exhibits broad scope, mild conditions, and excellent regioselectivity for a variety of substrates and fluoroalkyl fragments. The key to this C-centered radical relay is the matched rate of both photocatalytic and iron catalytic cycles, ensuring selective azidofluoroalkylation with a broad array of fluoroalkyl sources from trivial reagents.

Matrix Measure-Based Projective Synchronization on Coupled Neural Networks With Clustering Trees.

This article mainly studies the projective quasisynchronization for an array of nonlinear heterogeneous-coupled neural networks with mixed time-varying delays and a cluster-tree topology structure. For the sake of the mismatched parameters and the mutual influence among distinct clusters, the exponential and global quasisynchronization within a prescribed error bound instead of complete synchronization for the coupled neural networks with clustering trees is investigated. A kind of pinning impulsive controllers is designed, which will be imposed on the selected neural networks with some largest norms of error states at each impulsive instant in different clusters. By employing the concept of the average impulsive interval, the matrix measure method, and the Lyapunov stability theorem, sufficient conditions for the realization of the cluster projective quasisynchronization are derived. Meanwhile, in terms of the formula of variation of parameters and the comparison principle for the impulsive systems with mixed time-varying delays, the convergence rate and the synchronization error bound are precisely estimated. Furthermore, the synchronization error bound is efficiently optimized based on different functions of the impulsive effects. Finally, a numerical experiment is given to prove the results of theoretical analysis.

The Influence of Fly Ash on the Tensile Creep Prediction of High-Strength Concrete at Early Ages.

In this study, the tensile creep (TC) of high-strength concrete (HSC) containing 30 wt% fly ash was measured at early ages to investigate the applicability of creep prediction models for concrete containing FA, and to provide ideas to study the prediction model of concrete creep containing other SCMs in the future. The TC values obtained from the experiment were compared with the predicted values of six TC models. Then the accuracy of different models was evaluated by the ratio of predicted values to experimental values. Finally, the applicability of these models to the TC of HSC with fly ash was discussed at an early age. By comparison, it was found that when the loading age was 1d, 2d, and 3d, the ZC model (ZC are the initials for the word "Self-developed" in Chinese), which is a rheology-based model for TC, proposed by Yang.Y et al. agreed with the experimental values. The predicted values of the other five models deviated significantly from the tested ones. When the loading age was 5d and 7d, the calculated results of the ACI 2009R model were more accurate. Compared with the other five models, the time dependency of the paste with fly ash was considered in the ZC model, and parameter q of the ZC model was introduced in order to characterize the influence of fly ash on the paste at early ages. Therefore, this paper demonstrated both theoretically and experimentally that the ZC model can better predict the early-age TC of HSC with fly ash.

An ultracompact multimode interference wavelength splitter employing asymmetrical multi-section structures.

By using the film mode matching method, a novel design for asymmetrical multi-section 1.55/1.31 µm wavelength splitter based on multimode interference has been proposed and simulated, which can be effectively applied to wavelength multiplexer, self-biased photodiode, and other optical devices. Compared with the conventional wavelength splitter design, the length of the novel structure has been reduced to at least 1/5, showing better performance. The presented structure is also adequate for splitting other wavelengths and more tolerable fabrications.

Matrix Measure-Based Event-Triggered Impulsive Quasi-Synchronization on Coupled Neural Networks.

In this article, the quasi-synchronization for a kind of coupled neural networks with time-varying delays is investigated via a novel event-triggered impulsive control approach. In view of the randomly occurring uncertainties (ROUs) in the communication channels, the global quasi-synchronization for the coupled neural networks within a given error bound is considered instead of discussing the complete synchronization. A kind of distributed event-triggered impulsive controllers is presented with considering the Bernoulli stochastic variables based on ROUs, which works at each event-triggered impulsive instant. According to the matrix measure method and the Lyapunov stability theorem, several sufficient conditions for the realization of the quasi-synchronization are successfully derived. Combining with the mathematical methodology with the formula of variation of parameters and the comparison principle for the impulsive systems with time-varying delays, the convergence rate and the synchronization error bound are precisely estimated. Meanwhile, the Zeno behaviors could be eliminated in the coupled neural network with the proposed event-triggered function. Finally, a numerical example is presented to prove the results of theoretical analysis.

Direct Transformation of Nitrogen-Containing Methylheteroarenes to Heteroaryl Nitrile by Sodium Nitrite.

The cyanation reaction of methylheteroarenes with acetyl chloride and sodium nitrite via the radical process in high yields is reported. According to the control experiments, the reaction mechanism underwent radical progress. It is very useful in the pharmacy industry due to its metal-free and easy treatment conditions.

Dopant-free hole-transporting materials for stable Sb2(S,Se)3 solar cells.

Herein, we demonstrate that a thiophene-modified quinoxaline core small molecule can be applied in Sb2(S,Se)3 solar cells. We reveal that the interaction between thiophene and Sb2(S,Se)3 through the Sb-S bond essentially improves the interfacial hole-extraction ability. This study provides a cost-effective dopant-free hole-transporting material for inorganic thin film solar cell applications with excellent stability.

CsPbBr3 Nanocrystal Induced Bilateral Interface Modification for Efficient Planar Perovskite Solar Cells.

Organic-inorganic halide perovskite solar cells (PSCs) have drawn tremendous attention owing to their remarkable photovoltaic performance and simple preparation process. However, conventional wet-chemical synthesis methods inevitably create defects both in the bulk and at the interfaces of perovskites, leading to recombination of charge carriers and reduced stability. Herein, a bilateral interface modification to perovskites by doping room-temperature synthesized CsPbBr3 nanocrystals (CN) is reported. The ultrafast transient absorption measurement reveals that CN effectively suppresses the defect at the SnO2 /perovskite interface and boosts the interfacial electron transport. Meanwhile, the in situ Kelvin probe force microscopy and contact potential difference characterizations verify that the CN within the upper part of the perovskites enhances the built-in electric field, facilitating oriented migration of the carriers within the perovskite. Combining the superiorities of CN modifiers on both sides, the bilaterally modified CH3 NH3 PbI3 -based planar PSCs exhibit optimal power conversion efficiency exceeding 20% and improved device stability.

Direct Hydrothermal Deposition of Antimony Triselenide Films for Efficient Planar Heterojunction Solar Cells.

Antimony selenide (Sb2Se3) has attracted increasing attention in photovoltaic applications due to its unique quasi-one-dimensional crystal structure, suitable optical band gap with a high extinction coefficient, and excellent stability. As a promising light-harvesting material, the available synthetic methods for the fabrication of a high-quality film have been quite limited and seriously impeded both the fundamental study and the efficiency improvement. Here, we developed a facile and low-cost hydrothermal method for in situ deposition of Sb2Se3 films for solar cell applications. In this process, we apply KSbC4H4O7 and Na2SeSO3 as the antimony and selenium sources, respectively, in which thiourea (TU) serves as an additive to suppress the formation of Sb2O3 impurities. As a result, improved phase purity and enhanced crystallinity of the Sb2Se3 film are thus obtained, along with decreased trap states. Finally, the planar heterojunction Sb2Se3 solar cell delivered a power conversion efficiency of 7.9%, which is thus far the highest reported efficiency among solution-processed Sb2Se3 solar cells. This simple procedure and efficiency achievement demonstrate the great potential of the hydrothermal deposition process for the fabrication of high-efficiency Sb2Se3 solar cells.

Revealing composition and structure dependent deep-level defect in antimony trisulfide photovoltaics.

Antimony trisulfide (Sb2S3) is a kind of emerging light-harvesting material with excellent stability and abundant elemental storage. Due to the quasi-one-dimensional symmetry, theoretical investigations have pointed out that there exist complicated defect properties. However, there is no experimental verification on the defect property. Here, we conduct optical deep-level transient spectroscopy to investigate defect properties in Sb2S3 and show that there are maximum three kinds of deep-level defects observed, depending on the composition of Sb2S3. We also find that the Sb-interstitial (Sbi) defect does not show critical influence on the carrier lifetime, indicating the high tolerance of the one-dimensional crystal structure where the space of (Sb4S6)n ribbons is able to accommodate impurities to certain extent. This study provides basic understanding on the defect properties of quasi-one-dimensional materials and a guidance for the efficiency improvement of Sb2S3 solar cells.

Sequential Coevaporation and Deposition of Antimony Selenosulfide Thin Film for Efficient Solar Cells.

Antimony selenosulfide (Sb2 (S,Se)3 ) is an emerging low-cost, nontoxic solar material with suitable bandgap and high absorption coefficient. Developing effective methods for fabricating high-quality films would benefit the device efficiency improvement and deepen the fundamental understanding on the optoelectronic properties. Herein, equipment is developed that allows online introduction of precursor vapor during the reaction process, enabling sequential coevaporation of Sb2 Se3 and S powders for the deposition of Sb2 (S,Se)3 thin films. With this unique ability, it is revealed that the deposition sequence manipulates both the interfacial properties and optoelectronic properties of the absorber film. A power conversion efficiency of 8.0% is achieved, which is the largest value in vapor-deposition-derived Sb2 (S,Se)3 solar cells. The research demonstrates that multi-source sequential coevaporation is an efficient technique to fabricate high-efficiency Sb2 (S,Se)3 solar cells.

Protective Geopolymer Coatings Containing Multi-Componential Precursors: Preparation and Basic Properties Characterization.

This paper presents an experimental investigation on geopolymer coatings (GPC) in terms of surface protection of civil structures. The GPC mixtures were prepared with a quadruple precursor simultaneously containing fly ash (FA), ground granulated blast-furnace slag (GBFS), metakaolin (MK), and Portland cement (OPC). Setting time, compressive along with adhesive strength and permeability, were tested and interpreted from a perspective of potential applications. The preferred GPC with favorable setting time (not shorter than 120 min) and desirable compressive strength (not lower than 35 MPa) was selected from 85 mixture formulations. The results indicate that balancing strength and setting behavior is viable with the aid of the multi-componential precursor and the mixture design based on total molar ratios of key oxides or chemical elements. Adhesive strength of the optimized GPC mixtures was ranged from 1.5 to 3.4 MPa. The induced charge passed based on a rapid test of coated concrete specimens with the preferred GPC was 30% lower than that of the uncoated ones. Setting time of GPC was positively correlated with η[Si/(Na+Al)]. An abrupt increase of setting time occurred when the molar ratio was greater than 1.1. Compressive strength of GPC was positively affected by mass contents of ground granulated blast furnace slag, metakaolin and ordinary Portland cement, and was negatively affected by mass content of fly ash, respectively. Sustained seawater immersion impaired the strength of GPC to a negligible extent. Overall, GPC potentially serves a double purpose of satisfying the usage requirements and achieving a cleaner future.

Metal chloride perovskite thin film based interfacial layer for shielding lithium metal from liquid electrolyte.

Fabricating a robust interfacial layer on the lithium metal anode to isolate it from liquid electrolyte is vital to restrain the rapid degradation of a lithium metal battery. Here, we report that the solution-processed metal chloride perovskite thin film can be coated onto the lithium metal surface as a robust interfacial layer to shield the lithium metal from liquid electrolyte. Via phase analysis and density functional theory calculations, we demonstrate that the perovskite layer can allow fast lithium ion shuttle under a low energy barrier of 0.45 eV without the collapse of framework. Such perovskite modification can realize stable cycling of LiCoO2|Li cells with an areal capacity of 2.8 mAh cm-2 using thin lithium metal foil (50 µm) and limited electrolyte (20 µl mAh-1) for over 100 cycles at 0.5 C. The metal chloride perovskite protection strategy could open a promising avenue for advanced lithium metal batteries.

Composition engineering of Sb2S3 film enabling high performance solar cells.

Sb2S3 is a kind of stable light absorption materials with suitable band gap, promising for practical applications. Here we demonstrate that the engineering on the composition ratio enables significant improvement in the device performance. We found that the co-evaporation of sulfur or antimony with Sb2S3 is able to generate sulfur- or antimony-rich Sb2S3. This composition does not generate essential influence on the crystal structure, optical band and film formability, while the carrier concentration and transport dynamics are considerably changed. The device investigations show that sulfur-rich Sb2S3 film is favorable for efficient energy conversion, while antimony-rich Sb2S3 leads to greatly decreased device performance. With optimizations on the sulfur-rich Sb2S3 films, the final power conversion efficiency reaches 5.8%, which is the highest efficiency in thermal evaporation derived Sb2S3 solar cells.

Interfacial Engineering by Indium-Doped CdS for High Efficiency Solution Processed Sb2(S1- xSe x)3 Solar Cells.

Sb2(S1- xSe x)3 alloy material is a kind of encouraging material for realistically apposite solar cell because it benefits from high absorption coefficient, suitable bandgap, superior stability, and plentiful elemental storage. Interfacial engineering is vital for effective charge carrier transport in solar cells, which could upgrade the photoelectric conversion efficiency (PCE). Herein, as an interlayer, indium-doped CdS thin film fabricated by chemical bath deposition is found to remarkably enhance the photovoltaic performance of Sb2(S1- xSe x)3 solar cells. Mechanistic investigations show that the interlayer can both optically and electrically optimize the device quality. With that a PCE of 6.63% is obtained, which is the highest efficiency among the planar heterojunction solar cells and slightly higher than the reported record efficiency of mesoscopic Sb2(S1- xSe x)3-sensitized solar cells. This research provides an efficient interfacial engineering for high performance Sb2(S1- xSe x)3 solar cells.