A rhodium(III)‐catalyzed carboxylic acid directed decarboxylative CH/CH cross‐coupling of carboxylic acids with thiophenes has been developed. With a slight adjustment of the reaction conditions ...based on the nature of the substrates, aryl carboxylic acids with a variety of substituents could serve as suitable coupling partners, and a broad variety of functional groups were tolerated. This method provides straightforward access to biaryl scaffolds with diverse substitution patterns, many of which have conventionally been synthesized through lengthy synthetic sequences. An illustrative example is the one‐step gram‐scale synthesis of a biologically active 3,5‐substituted 2‐arylthiophene by way of the current method.
Who was in control? A rhodium(III)‐catalyzed carboxylic acid directed decarboxylative CH/CH cross‐coupling of benzoic acids with thiophenes has been developed. This method provides straightforward access to biaryl scaffolds with diverse substitution patterns, many of which previously required lengthy synthetic sequences.
The effects of nano-silica (NS) on setting time and early strengths of high volume slag mortar and concrete have been experimentally studied. Effects of NS dosages, size and dispersion methods on ...strength development of high volume slag mortars were also investigated. A constant water-to-cementitious materials ratio (w/cm) 0.45 was used for all mixtures. The results indicate that the incorporation of a small amount of NS reduced setting times, and increased 3- and 7-day compressive strengths of high-volume slag concrete, significantly, in comparison to the reference slag concrete with no silica inclusion. Compressive strength of the slag mortars were increased with the increase in NS dosages from 0.5% to 2.0% by mass of cementitious materials at various ages up to 91days. The strengths of the slag mortars were generally increased with the decrease in the particles size of silica inclusions at early age. Ultra-sonication of nano-silica with water is probably a better method for proper dispersion of nano-silica than mechanical mixing method.
Grain size is an important component trait of grain yield, which is frequently threatened by abiotic stress. However, little is known about how grain yield and abiotic stress tolerance are regulated. ...Here, we characterize GSA1, a quantitative trait locus (QTL) regulating grain size and abiotic stress tolerance associated with metabolic flux redirection. GSA1 encodes a UDP-glucosyltransferase, which exhibits glucosyltransferase activity toward flavonoids and monolignols. GSA1 regulates grain size by modulating cell proliferation and expansion, which are regulated by flavonoid-mediated auxin levels and related gene expression. GSA1 is required for the redirection of metabolic flux from lignin biosynthesis to flavonoid biosynthesis under abiotic stress and the accumulation of flavonoid glycosides, which protect rice against abiotic stress. GSA1 overexpression results in larger grains and enhanced abiotic stress tolerance. Our findings provide insights into the regulation of grain size and abiotic stress tolerance associated with metabolic flux redirection and a potential means to improve crops.
Improving the stability of lead halide perovskite quantum dots (QDs) in a system containing water is the key for their practical application in artificial photosynthesis. Herein, we encapsulate ...low‐cost CH3NH3PbI3 (MAPbI3) perovskite QDs in the pores of earth‐abundant Fe‐porphyrin based metal organic framework (MOF) PCN‐221(Fex) by a sequential deposition route, to construct a series of composite photocatalysts of MAPbI3@PCN‐221(Fex) (x=0–1). Protected by the MOF the composite photocatalysts exhibit much improved stability in reaction systems containing water. The close contact of QDs to the Fe catalytic site in the MOF, allows the photogenerated electrons in the QDs to transfer rapidly the Fe catalytic sites to enhance the photocatalytic activity for CO2 reduction. Using water as an electron source, MAPbI3@PCN‐221(Fe0.2) exhibits a record‐high total yield of 1559 μmol g−1 for photocatalytic CO2 reduction to CO (34 %) and CH4 (66 %), 38 times higher than that of PCN‐221(Fe0.2) in the absence of perovskite QDs.
Pores and dots: CH3NH3PbI3 (MAPbI3) perovskite quantum dots were encapsulated in the pores of iron‐porphyrin derived metal–organic frameworks (MOFs) of PCN‐221(Fex) to give an efficient photocatalytic system, which has significantly enhanced catalytic efficiency and stability for visible‐light‐driven CO2 reduction using water as an electron source.
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•The g-C3N4-TiO2 composites were obtained by simple solid state sintering.•The composites were direct contact Z-scheme without an electron mediator.•TiO2 with large amount of SETOV ...was obtained by dehydration of NTA.
Direct contact Z-scheme g-C3N4-TiO2 nanocomposites without an electron mediator are prepared via simple annealing the mixture of bulk g-C3N4 and nanotube titanic acid (NTA) in air at 600°C for 2h. In the process of annealing, the bulk g-C3N4 transformed to ultra-thin g-C3N4 nanosheets, and NTA converted to a novel anatase TiO2, then the two components formed a close interaction. The XPS result reveals that some amount of nitrogen is doped into this novel-TiO2, and g-C3N4 nanosheets exist in the composites. The results of XRD, TEM and TG indicate that the thickness of g-C3N4 nanosheets is very thin. The ESR spectrum shows the existence of Ti3+ and single-electron-trapped oxygen vacancy in the 30%g-C3N4-TiO2 composites. In photocatalytic activity test, the 30%g-C3N4-TiO2 nanocomposites showed an excellent photo-oxidation activity of propylene under visible light irradiation (λ≥420nm), and the removal efficiency of propylene reached as high as 56.6%, and the activity kept nearly 82% after four consecutive recycles. Photoluminescence (PL) result using terephthalic acid (TA) as a probe molecule indicated that the g-C3N4-TiO2 nanocomposites displayed a Z-sheme photocatalytic reaction system and this should be the main reason for the high photocatalytic activity. A possible photocatalytic mechanism was proposed on the basis of PL result and transient photocurrent-time curves.
This paper presents a systematic study of structure and mechanical behavior of Ti/Fe explosive-bonded interfaces. The transient fluid-like behavior at the bonding zone is simulated using Smoothed ...Particle Hydrodynamic (SPH) numerical method. The interface is featured by a wave structure, resulted from heavy plastic deformation during the explosive welding. Melted zone resulted from the trapped jetting is surrounded by strongly deformed bulk materials. Fe2Ti intermetallic compounds with a mixture of FeTi+Fe phases are observed in the melted zone. A reaction layer (~700nm) consisted of nano-sized FeTi grains is formed at Ti/Fe material boundary. Nanoindentation tests and fracture observation confirm the brittle nature of Fe-Ti intermetallics formed in the explosive-bonded joint. Extremely temperature accumulated near the interface leads to recovery and recrystallization in deformed grains, which can accommodate relatively large strain near the interface.
3D food printing is an emerging technology with a potential to influence the food manufacturing sector. Rheological properties of food inks are critical for their successful 3D printing. However, the ...relationships between rheological properties and 3D printability have not been clearly defined in food systems. In this work, a gel model system composed of carrageenan-xanthan-starch was prepared for an extrusion-based 3D food printer. The 3D printing process was divided into three stages and the corresponding rheological properties of inks for each stage were determined, namely extrusion stage (yield stress, viscosity and shear-thinning behaviour), recovery stage (shear recovery and temperature recovery properties) and self-supporting stage (complex modulus G* and yield stress at room temperature). Finally, 3D printability of the model inks was systematically studied starting with printing lines/pentagram (one dimensional, 1D structure) to printing lattice scaffold (two dimensional, 2D structure) and finally printing cylinders (three dimensional, 3D structure). Results demonstrated that addition of starch and xanthan gum in k-carrageenan based inks increased inks' gelation temperature (Tgelation), viscosity (within shear rate of 0.01–100 1/s), yield stress, G*, enhanced shear-thinning (thixotropic) behaviour and reduced time-dependence of modulus (temperature recovery). Rheological responses of yield stress (cross-over point where G′ (elastic modulus) equals to G′′ (viscous modulus) in the stress sweep tests) and shear-thinning behaviour (viscosity decreased when shear rate increased) were closely related to ink's extrudability. Inks' gelation temperature (Tgelation) and time-dependent behaviour (gelation time, tgel) significantly affected their printability and shape retention performance. The mechanical strength of the ink is important to be self-supporting, especially for 3D structures. Insights achieved from this study could provide guidance on improving 3D printability of foods that use hydrocolloids as a printing aid.
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•Thixotropic and thermo-reversible gel system was used as a model in 3D printing.•Ink's rheology and 3D printability was correlated in the whole printing process.•1D, 2D, 3D structures were fabricated and correlated with ink's rheology.
Change detection based on remote sensing (RS) data is an important method of detecting changes on the Earth’s surface and has a wide range of applications in urban planning, environmental monitoring, ...agriculture investigation, disaster assessment, and map revision. In recent years, integrated artificial intelligence (AI) technology has become a research focus in developing new change detection methods. Although some researchers claim that AI-based change detection approaches outperform traditional change detection approaches, it is not immediately obvious how and to what extent AI can improve the performance of change detection. This review focuses on the state-of-the-art methods, applications, and challenges of AI for change detection. Specifically, the implementation process of AI-based change detection is first introduced. Then, the data from different sensors used for change detection, including optical RS data, synthetic aperture radar (SAR) data, street view images, and combined heterogeneous data, are presented, and the available open datasets are also listed. The general frameworks of AI-based change detection methods are reviewed and analyzed systematically, and the unsupervised schemes used in AI-based change detection are further analyzed. Subsequently, the commonly used networks in AI for change detection are described. From a practical point of view, the application domains of AI-based change detection methods are classified based on their applicability. Finally, the major challenges and prospects of AI for change detection are discussed and delineated, including (a) heterogeneous big data processing, (b) unsupervised AI, and (c) the reliability of AI. This review will be beneficial for researchers in understanding this field.
3D printing technology and its extension 4D printing technology have been extensively developed since it was proposed and applied to many industries, including aerospace, biomedical, and food fields. ...However, there are material limitations for 3D/4D food printing, as some natural food gels cannot be directly applied to 3D/4D food printing, and most natural food gels tend to have poor printing characteristics, which are difficult or impossible to print. Additives in food have a long history of application, which can change some properties of natural food gels. Suitable rheological property is the primary condition of 3D/4D food printing, most of the research is about improving the rheological property of ink, while the research on improving the thermal property, electrostatic property, nutritional property and sensory quality of ink (especially electrostatic property and nutritional property) is still insufficient. This article discusses the printing characteristics (rheological properties, thermal properties, electrostatic properties, nutritional properties, and sensory qualities) of natural food gels that are improved by additives in 3D/4D food printing, mainly from three types of additives: lipids, hydrocolloids, and carbohydrates.
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•Commonly used 3D/4D food printing inks and novel additives are outlined.•Printed inks are classified according to their printing characteristics.•Methods for improving printing properties of natural food gels by novel additives were proposed.•Novel additives were used to enhance the nutrition of 3D/4D printed food.•Novel additives in enhancing rheological, electrostatic and thermal properties of natural food gels were introduced.
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