The catalytic conversion of lignocellulosic biomass to aviation fuel is identified as a key strategy to alleviate high operating costs and serious environmental pollution caused by using ...petroleum-derived fuels. Aviation fuel with stringent end-use requirements consists of several specific hydrocarbon compositions, and the conversion of lignocellulose to aviation fuel is more challenging than that to other fuels. In this study, the latest cutting-edge innovations on the catalytic conversion of lignocellulose to aviation fuel was summarized. Promising routes for the catalytic conversion of cellulose, hemicellulose, lignin, and their derivatives were elaborated, with emphasis on those catalytic approaches including depolymerization of C–O bonds, formation/rearrangement of C–C bonds, and hydrodeoxygenation (HDO) removal of oxygen-containing functional groups. Innovations on reaction mechanism exploration, catalyst development, solvent screening, and reaction condition optimization were introduced. It revealed that a 100% biomass-derived aviation fuel could be produced by catalytic methods with the full utilization of all lignocellulosic compositions. Straight and branched paraffins in aviation-fuel range could be generated from cellulose and hemicellulose via various intermediates including 5-hydroxymethylfurfural (HMF), furfural, levulinic acid, and γ−valerolactone. The degradation and HDO conversion of lignin could yield aromatics and cycloparaffins in aviation range. The development of hydrothermal stable catalysts for the controllable formation of C–C bonds among platform chemicals from carbohydrates as well as for the efficient HDO conversion of fuel precursors is particularly important.
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•All compositions in lignocellulose can be catalytically converted to aviation fuel.•A 100% biomass-derived aviation fuel can be produced by catalytic methods.•Paraffins for aviation fuel can be produced from cellulose and hemicellulose.•Cycloalkanes and aromatics for aviation fuel can be generated from lignin.
Good interfacial compatibility is the key to realize the full potential of metal–organic framework-based mix matrix membranes for gas separation. Here we report a new approach that uses polyimide ...brushes covalently grafted on the MOF surface to engineer the MOF-polymer interface. Benefiting from the strong brush–brush interaction, polyimide grafted MOF particles can form a stand-alone membrane at 88 wt % MOF loading without the addition of polymeric matrix. Compared to traditional mixed-matrix membranes, the modified membranes exhibit improved ductility up to 472%, reduced interfacial tearing phenomenon under shear force, decreased matrix chain mobility, and improved plasticization resistance against CO2. Most importantly, with increasing MOF loading, only the modified membranes exhibit simultaneous increase of selectivity and permeability for CO2/N2 and CO2/CH4 separation, following the trend predicted by the modified Maxwell model.
The contradiction between the rising demands of optical chirality sensing and the failure in chiral detection of cryptochiral compounds encourages researchers to find new methods for chirality ...amplification. Inspired by planar chirality and the host–guest recognition of pillararenes, we establish a new concept for amplifying CD signals of cryptochiral molecules by pillararene host–guest complexation induced chirality amplification. The planar chirality of pillararenes is induced and stabilized in the presence of the chiral guest, which makes the cryptochiral molecule detectable by CD spectroscopy. Several chiral guests are selected in these experiments and the mechanism of chiral amplification is studied with a non‐rotatable pillararene derivative and density functional theory calculations. We believe this work affords deeper understanding of chirality and provides a new perspective for chiral sensing.
Intrinsic advantages and uniqueness in chirality amplification are exhibited by pillararenes. By combining high affinity for guests, detectable UV absorption, and inducible chirality they can be used for detecting cryptochiral compounds.
The control of surface properties of all inorganic cesium lead halide perovskite (CsPbX3; X = Cl, Br, or I) quantum dots (QDs) is essential to achieve excellent stability and high photoluminescence ...quantum yields (PLQYs). Herein, a facile method was performed to simultaneously enhance the stability and PLQYs of CsPbX3 QDs by a ZnX2/hexane solution post-treatment. We show that the halogen defect on the surface of CsPbX3 QDs can be treated in a controlled way, whereby the “black dots” that adhered on the surface as observed by transmission electron microscopy have be completely removed, resulting in enhanced stability and photoluminescence. The PLQYs of CsPbCl3, CsPbBr3, and CsPbI3 increased from 4, 58, and 63% to 86, 93, and 95%, respectively, and the origin of the “black dots” as well as their transformation mechanism has been demonstrated. As a result, the poly(dimethylsiloxane) composite films created by encapsulating stable and nearly defect-free green-emitting CsPbBr3, the red-emitting K2SiF6:Mn4+ phosphor, and a blue emission GaN chip were prepared and used to fabricate a remote-type white light-emitting diode device, which exhibits a high luminescence efficiency (≤98 lm/W) and a wide color gamut (∼130% of the National Television Standard Committee standard), suggesting the potential for liquid crystal display backlight application.
Laser keyhole welding of dissimilar metals has broad applications in various industrial fields. However, dissimilar metal mixing in the molten pool often causes the formation of detrimental ...intermetallic compounds that can undermine the performances of the dissimilar metal joints. In this study, the metal mixing process in laser keyhole welding of dissimilar metals is investigated with a combination of experimental and modeling approaches. The parametric experimental study is conducted to reveal the effects of laser power, welding speed, and heat input on the metal mixing in the fusion zone. Ex-situ energy-dispersive X-ray spectroscopy element mapping is used to characterize the metal mixing status in the fusion zone. To investigate the underlying physics of the welding process, a numerical model is developed to simulate the heat transfer, fluid flow, and metal mixing in the molten pool. It is found that the recoil pressure contributes to an upward flow that pushes copper to migrate from the bottom of the molten pool to the top. Meanwhile, the Marangoni force generates one backward flow and two side vortices that facilitate the metal mixing. An increase of laser power increases both the recoil pressure and the Marangoni stress, which drives more copper to migrate upward and mix with aluminum. An increase of welding speed reduces the molten pool lifetime, which reduces the metal mixing by the fluid flow. The investigation of dissimilar metal redistribution provides insights regarding the formation of intermetallic compounds in the joints, which is valuable for the design and optimization of the welding process in different industries.
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•The underlying physics of metal mixing in laser welding of dissimilar metals are investigated.•The chemical concentration field and metal mixing pattern are characterized by EDS element mapping.•The effects of recoil pressure and Marangoni force on fluid flow and metal mixing are studied.•The effects of welding parameters on the metal mixing are studied.
This paper summarizes the current knowledge regarding the possible modes of action and nutritional factors involved in the use of essential oils （EOs） for swine and poultry. EOs have recently ...attracted increased interest as feed additives to be fed to swine and poultry, possibly replacing the use of antibiotic growth promoters which have been prohibited in the European Union since 2006. In general, EOs enhance the production of digestive secretions and nutrient absorption, reduce pathogenic stress in the gut, exert antioxidant properties and reinforce the animal＇s immune status, which help to explain the enhanced performance observed in swine and poultry. However, the mechanisms involved in causing this growth promotion are far from being elucidated, since data on the complex gut ecosystem, gut function, in vivo oxidative status and immune system are still lacking. In addition, limited information is available regarding the interaction between EOs and feed ingredients or other feed additives （especially pro- or prebiotics and organic acids）. This knowledge may help feed formulators to better utilize EOs when they formulate diets for poultry and swine.
...the infection control experts conducted standardized pre-job training. ...the infection control experts monitored the entire process before and after the medical staff entering the isolation ...wards. ...the COVID-19 outbreak is a significant threat to international health and a big challenge for all of us.
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•The tectonic evolution of the ECSSB is well-regulated in three stages geologically.•The ECSSB tectonically migrated eastward in response to the westward subduction of the Pacific ...Plate.•75 mm/a is a key value of the Pacific Plate subduction to the ECSSB evolution.
The East China Sea Shelf Basin is one of the Mesozoic-Cenozoic basins located in the edge of eastern China continent whose formation and evolution are closely related to the subduction of the Pacific Plate. However, the underlying correlations between the tectonic evolution of the East China Sea Shelf Basin and the Pacific Plate subduction (65 Ma to present) remain poorly understood. In this paper, the basin is divided into western and eastern depression groups to further study its tectonic evolution. In combination with the characteristics of Pacific Plate subduction, this paper performs a coupling analysis of the basin evolution regarding its migration direction and evolution rate. The results of balanced section and deformation rate analyses reveal that the East China Sea Shelf Basin experienced different regional activities during the Cenozoic, which could be summarized as four geologic periods and three tectonic evolution stages. In this interpretation, it is recognized that tectonic activity occurred in the western depression group and then shifted to depocenters of the eastern group. In contrast, the Pacific Plate subducted westwards beneath the Eurasian Plate over the same geologic time span. Surprisingly, a slightly negative correlation between the intensity of the tectonic deformation of the East China Sea Shelf Basin and the subduction rate of the Pacific Plate is demonstrated when the subduction rate is no more than 75 mm/a. However, the basin deformation intensity increases with the plate subduction rate after 75 mm/a. The results of this work have implications for explaining the major role that the subduction of the Pacific Plate played in the formation and evolution of the eastern China basins.
We report a new class of porous liquids (PLs) using internally functionalized metal–organic framework (MOF) particles as pore carriers and poly(dimethylsiloxane) as bulky solvents. Using a ...generalizable noncovalent surface-initiated controlled radical polymerization technique, a series of isoreticular UiO-66 particles were dispersed in a liquid PDMS matrix with excellent homogeneity and colloidal stability. Benefiting from the inherent properties of PDMS, the PLs exhibit low vapor pressure, high thermal stability, and fluidity down to −35 °C. Attributed to the bulkiness of PDMS and its inherent high permeability, the sorption properties of the MOF fillers can be largely retained in their respective PLs as confirmed by low-pressure CO2, N2, Xe, and H2O sorption isotherms. The permanent porosity of the PLs can also be largely preserved even after 15 months of storage. Finally, we demonstrate that by tuning the molecular weight and polymer chain architecture of PDMS, it is possible to preserve the permanent porosity of a mesoporous MOF, MIL-101(Cr), within a PL.
Multilevel inverters are one of the preferred solutions for medium-voltage and high-power applications and have found successful industrial applications. Five-level active neutral point clamped ...inverter (5L-ANPC) is one of the most popular topologies among five-level inverters. A six-switch 5L-ANPC (6S-5L-ANPC) topology is proposed. Compared to the conventional 5L-ANPC inverters, the 6S-5L-ANPC reduces two active switches and has lower conduction loss. The proposed modulation enables the 6S-5L-ANPC inverter to operate under both active and reactive power conditions. The flying-capacitor capacitance is designed under both active and reactive power conditions. The analysis shows the proposed topology is suitable for photovoltaic grid-connected applications. A 1 KVA single-phase experimental prototype is built to verify the validity and flexibility of the proposed topology and modulation method.
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