Switchable polymerization is emerging as a powerful tool to construct block copolymers directly from mixtures of monomers.However,current achievements typically iterate between two polymerization cycles to afford prod...Switchable polymerization is emerging as a powerful tool to construct block copolymers directly from mixtures of monomers.However,current achievements typically iterate between two polymerization cycles to afford products with fixed sequences and compositions.Herein,we report the triethylborane/1,8-diazabicyclo[5.4.0]undec-7-ene(Et_3B/DBU)pair-mediated four-component switchable polymerization of propylene oxide(PO),CO_(2),phthalic anhydride(PA),and racemic lactide(rac-LA),which enables the on-demand synthesis of four different block copolymers,i.e.,poly(propylene phthalate)-b-polylactide(PPE-b-PLA),PPE-b-PLA-b-poly(propylene carbonate)(PPC),PPE-b-PPC-b-PLA,and PPE-b-PPCb-poly(propylene oxide)(PPO),through rationally modulating the Lewis pair(LP)ratio.Core to this protocol is that increasing the loading of Et_(3)B accelerates the ring-opening of PO while impeding the reactivity of rac-LA,thus allowing for fine-tuning of the thermodynamic and kinetic of the switchable polymerization.Therefore,the four polymerization cycles involving PO/PA ring-opening copolymerization(ROCOP),PO/CO_(2) ROCOP,rac-LA ring-opening polymerization(ROP),and PO ROP can be connected and discriminated in precisely programmed manners.展开更多
Octopuses,due to their flexible arms,marvelous adaptability,and powerful suckers,are able to effortlessly grasp and disengage various objects in the marine surrounding without causing devastation.However,manipulating ...Octopuses,due to their flexible arms,marvelous adaptability,and powerful suckers,are able to effortlessly grasp and disengage various objects in the marine surrounding without causing devastation.However,manipulating delicate objects such as soft and fragile foods underwater require gentle contact and stable adhesion,which poses a serious challenge to now available soft grippers.Inspired by the sucker infundibulum structure and flexible tentacles of octopus,herein we developed a hydraulically actuated hydrogel soft gripper with adaptive maneuverability by coupling multiple hydrogen bond-mediated supramolecular hydrogels and vat polymerization three-dimensional printing,in which hydrogel bionic sucker is composed of a tunable curvature membrane,a negative pressure cavity,and a pneumatic chamber.The design of the sucker structure with the alterable curvature membrane is conducive to realize the reliable and gentle switchable adhesion of the hydrogel soft gripper.As a proof-of-concept,the adaptive hydrogel soft gripper is capable of implement diversified underwater tasks,including gingerly grasping fragile foods like egg yolks and tofu,as well as underwater robots and vehicles that station-keeping and crawling based on switchable adhesion.This study therefore provides a transformative strategy for the design of novel soft grippers that will render promising utilities for underwater exploration soft robotics.展开更多
The synthesis of carbon supporter/nanoscale high-entropy alloys(HEAs)electromagnetic response composites by carbothermal shock method has been identified as an advanced strategy for the collaborative competition engin...The synthesis of carbon supporter/nanoscale high-entropy alloys(HEAs)electromagnetic response composites by carbothermal shock method has been identified as an advanced strategy for the collaborative competition engineering of conductive/dielectric genes.Electron migration modes within HEAs as manipulated by the electronegativity,valence electron configurations and molar proportions of constituent elements determine the steady state and efficiency of equivalent dipoles.Herein,enlightened by skin-like effect,a reformative carbothermal shock method using carbonized cellulose paper(CCP)as carbon supporter is used to preserve the oxygencontaining functional groups(O·)of carbonized cellulose fibers(CCF).Nucleation of HEAs and construction of emblematic shell-core CCF/HEAs heterointerfaces are inextricably linked to carbon metabolism induced by O·.Meanwhile,the electron migration mode of switchable electronrich sites promotes the orientation polarization of anisotropic equivalent dipoles.By virtue of the reinforcement strategy,CCP/HEAs composite prepared by 35%molar ratio of Mn element(CCP/HEAs-Mn_(2.15))achieves efficient electromagnetic wave(EMW)absorption of−51.35 dB at an ultra-thin thickness of 1.03 mm.The mechanisms of the resulting dielectric properties of HEAs-based EMW absorbing materials are elucidated by combining theoretical calculations with experimental characterizations,which provide theoretical bases and feasible strategies for the simulation and practical application of electromagnetic functional devices(e.g.,ultra-wideband bandpass filter).展开更多
Smart windows(SWs)garner significant potential in green buildings owing to their capability of on-demand tuning the solar gains.Apart from solar regulation,people always desire a type of slippery SW which can repel th...Smart windows(SWs)garner significant potential in green buildings owing to their capability of on-demand tuning the solar gains.Apart from solar regulation,people always desire a type of slippery SW which can repel the surface hydrous contaminants for anti-fouling application.Unfortunately,the up-to-date slippery SWs that respond to electrical/thermal stimuli have drawbacks of inferior durability and high energy-consumption,which greatly constrain their practical usability.This article presents our current work on an ultra-robust and energy-efficient near-infrared-responsive smart window(NIR-SW)which can regulate the optical transmittance and droplet’s adhesion in synergy.Significantly,laser-printing strategy enables us to seed the shape-memory photothermal microwalls on a transparent substrate,which can promote daylighting while maintaining privacy by near-infrared(NIR)switching between being transparent and opaque.As a light manipulator,it turns transparent with NIR-activated erect microwalls like an open louver;however,it turns opaque with the pressure-fixed bent microwalls akin to a closed louver.Simultaneously,the droplets can easily slip on the surface of erect microwalls similar to a classical lotus effect;by contrast,the droplets will tightly pin on the surface of bent microwalls analogous to the prevalent rose effect.Owing to shape-memory effect,this optical/wettability regulation is thus reversible and reconfigurable in response to the alternate NIR/pressure trigger.Moreover,NIR-SW unfolds a superior longevity despite suffering from the raindrop’s impacting more than 10000 cycles.Remarkably,such a new-type SW is competent for thermal management,anti-icing system,peep-proof screen,and programmable optics.This work renders impetus for the researchers striving for self-cleaning intelligent windows,energy-efficient greenhouse,and so forth.展开更多
Green extraction of bioactive components from natural sources has been a hot topic in the field of chemistry and biology.As a kind of green solvents,deep eutectic solvents(DESs)have unique advantages in the extraction...Green extraction of bioactive components from natural sources has been a hot topic in the field of chemistry and biology.As a kind of green solvents,deep eutectic solvents(DESs)have unique advantages in the extraction of bioactive substances.In recent years,as a new subgroup of DESs,the switchable deep eutectic solvents(SDESs)can realize reversible phase switching between hydrophobic and hydrophilic by external driving forces(CO_(2)/p H/temperature),allowing for the extraction of different polar components while avoiding the problem of difficult recovery of DESs.The application of SDESs reduces the consumption of large amounts of organic solvents during the extraction process,thereby promoting sustainability.In the meanwhile,it presents an advantage over traditional extraction methods in preserving product activity.Based on the recent researches on SDESs,this work summarized the composition,driving factors,and conversion mechanism of SDESs.The applications of SDESs in the extraction of natural products were primarily highlighted to provide a reference for future research.展开更多
In recent decades,brain tumors have emerged as a serious neurological disorder that often leads to death.Hence,Brain Tumor Segmentation(BTS)is significant to enable the visualization,classification,and delineation of ...In recent decades,brain tumors have emerged as a serious neurological disorder that often leads to death.Hence,Brain Tumor Segmentation(BTS)is significant to enable the visualization,classification,and delineation of tumor regions in Magnetic Resonance Imaging(MRI).However,BTS remains a challenging task because of noise,non-uniform object texture,diverse image content and clustered objects.To address these challenges,a novel model is implemented in this research.The key objective of this research is to improve segmentation accuracy and generalization in BTS by incorporating Switchable Normalization into Faster R-CNN,which effectively captures the fine-grained tumor features to enhance segmentation precision.MRI images are initially acquired from three online datasets:Dataset 1—Brain Tumor Segmentation(BraTS)2018,Dataset 2—BraTS 2019,and Dataset 3—BraTS 2020.Subsequently,the Switchable Normalization-based Faster Regions with Convolutional Neural Networks(SNFRC)model is proposed for improved BTS in MRI images.In the proposed model,Switchable Normalization is integrated into the conventional architecture,enhancing generalization capability and reducing overfitting to unseen image data,which is essential due to the typically limited size of available datasets.The network depth is increased to obtain discriminative semantic features that improve segmentation performance.Specifically,Switchable Normalization captures the diverse feature representations from the brain images.The Faster R-CNN model develops end-to-end training and effective regional proposal generation,with an enhanced training stability using Switchable Normalization,to perform an effective segmentation in MRI images.From the experimental results,the proposed model attains segmentation accuracies of 99.41%,98.12%,and 96.71%on Datasets 1,2,and 3,respectively,outperforming conventional deep learning models used for BTS.展开更多
3D(three-dimensional)printing of soft/tough hydrogels has been widely used in flexible electronics,regenerative medicine,and other fields.However,due to their loose crosslinking,strong hydration and plasticizing effec...3D(three-dimensional)printing of soft/tough hydrogels has been widely used in flexible electronics,regenerative medicine,and other fields.However,due to their loose crosslinking,strong hydration and plasticizing effect of solvent(typically water)and susceptibility to swelling,the printed hydrogels always suffer from bearing compressive stress and shear stress.Here we report a 3D photo-printable hard/soft switchable hydrogel composite which is enabled by the phase transition(liquid/solid transition)of supercooled hydrated salt solution(solvents)within hydrogel.In hard status,it achieved a hardness of 86.5 Shore D(comparable to hard plastics),a compression strength of 81.7 MPa,and Young’s modulus of 1.2 GPa.These mechanical property parameters far exceed those of any currently 3D printed hydrogels.The most interesting thing is that the soft/hard states are easily switchable and this process can be repeated for many times.In the supercooled state,the random arrangement of liquid solvent molecules within hydrogels makes it as soft as conventional hydrogels.Upon artificial seeding of the crystal nucleus,the solvent in hydrogel undergoes rapid crystallization,resulting in the in-situ formation of numerous rigids,ordered rod-like nanoscale crystals uniformly embedded within the hydrogel matrix.This hierarchical structure remarkably enhances the Young’s modulus from kPa to GPa.Furthermore,the softness of hydrogel can be restored by heating and then cooling down to recover the supercooled state of the solvent.Taking advantage of soft/hard status switching,the hydrogel can conform to complex surface morphologies in its soft state and subsequently freeze that shape through crystallization,enabling rapid mold fabrication.Moreover,a shape fixation and recyclable smart hydrogel medical plaster bandage was also developed,capable of conforming the limb shapes and providing adequate support for the bone fracture patients after 10 min of crystallization.Our work suggests a bright future for the direct use of hard hydrogel as a robust industrial material.展开更多
As a highly energy-efficient and sensitive radiation source,narrowband thermal emitters provide an ideal solution for non-contact gas detection,enabling the widespread application of mid-infrared“molecular fingerprin...As a highly energy-efficient and sensitive radiation source,narrowband thermal emitters provide an ideal solution for non-contact gas detection,enabling the widespread application of mid-infrared“molecular fingerprint”technology.However,most narrowband thermal emitters lack reconfigurability,limiting their adaptability in practical applications.In this study,we propose a novel dual-band switchable narrowband thermal emitter in the mid-infrared region.The emitter consists of an aperiodic Ge/SiO_(2)/Ge/SiO_(2)(GSGS)structure and a phase change material In_(3)SbTe_(2)(IST).When IST is in the crystalline state,the emitter achieves narrowband emission peaks at wavelengths of 3.79μm and 6.12μm,corresponding to the“on”state.However,when IST transitions to the amorphous state,the dual-band high emission disappears and it features angle-and polarization-independent behavior,representing the“off”state.Furthermore,we verify the physical mechanism behind the high emission through phase and amplitude calculations as well as electric field distribution analysis.Notably,the introduction of the IST provides an additional degree of freedom for tunability.Furthermore,by adjusting the thickness of the spacer layer,the emitter can be precisely tuned to match the characteristic absorption peaks of various mid-infrared gases,such as CH_(4),CO_(2),CO,and NO,enabling multi-gas detection in mixed gas environments.The proposed thermal emitter serves as an effective and low-cost alternative for dual-band narrowband mid-infrared light sources,contributing to the advancement of multi-gas detection strategies.展开更多
We demonstrate that the sliding motion between two layers of the newly discovered ferroelectric and topologically trivial bismuth(Bi)monolayer[Nature 61767(2023)]can induce a sequence of topological phase transitions,...We demonstrate that the sliding motion between two layers of the newly discovered ferroelectric and topologically trivial bismuth(Bi)monolayer[Nature 61767(2023)]can induce a sequence of topological phase transitions,alternating between Z_(2)trivial and nontrivial states.The lateral shift,while preserving spatial symmetry,can switch the quantum spin Hall state on and of.The sliding-induced changes in out-of-plane atomic buckling,which are directly coupled to in-plane ferroelectricity,are shown to signifcantly modulate the band gap and drive the topological phase transitions.We map out the topological phase diagram and in-plane ferroelectricity with respect to sliding displacements.With appropriate sliding,the bismuth bilayer can transition into a nontrivial polar metal,exhibiting a pronounced shift current response arising from interband geometric quantities of electronic bands.Moreover,bilayer Bi supports a sliding-tunable nonlinear anomalous Hall response resulting from the geometric Berry curvature dipole.Confgurations that are Z_(2)nontrivial can generate drastically different transverse currents orthogonal to the external electric feld,as both the direction and magnitude of the Berry curvature dipole at the Fermi level are highly sensitive to the sliding displacement.Our results suggest that bilayer bismuth,with its ability to generate multiple types of geometric currents,ofers a versatile platform for power-efcient“Berry slidetronics”for multistate memory applications integrating both band topology and ferroelectricity.展开更多
Switchable radiative cooling/heating holds great promise for mitigating the global energy and environmental crisis.Here,we reported a cost-effective,high-strength Janus film through surface optical engineering waste p...Switchable radiative cooling/heating holds great promise for mitigating the global energy and environmental crisis.Here,we reported a cost-effective,high-strength Janus film through surface optical engineering waste paper with one side decorated by a hydrophobic polymeric cooling coating consisting of micro/nanopore/particle hierarchical structure and the other side coated with hydrophilic MXene nanosheets for heating.The cooling surface demonstrates high solar reflectivity(96.3%)and infrared emissivity(95.5%),resulting in daytime/nighttime sub-ambient radiative cooling of 6℃/8℃with the theoretical cooling power of 100.6 and 138.5Wm^(−2),respectively.The heating surface exhibits high solar absorptivity(83.7%)and low infrared emissivity(15.2%),resulting in excellent radiative heating capacity for vehicle charging pile(~6.2℃)and solar heating performance.Impressively,the mechanical strength of Janus film increased greatly by 563%compared with that of pristine waste paper,which is helpful for its practical applications in various scenarios for switchable radiative thermal management through mechanical flipping.Energy-saving simulation results reveal that significant total energy savings of up to 32.4MJm^(−2) can be achieved annually(corresponding to the 12.4%saving ratio),showing the immense importance of reducing carbon footprint and promoting carbon neutrality.展开更多
This study presents the design of an erbium-doped fiber laser(EDFL) featuring switchable wavelength intervals achieved through the implementation of cascaded and parallel Lyot filters. The proposed laser system utiliz...This study presents the design of an erbium-doped fiber laser(EDFL) featuring switchable wavelength intervals achieved through the implementation of cascaded and parallel Lyot filters. The proposed laser system utilizes a cascaded and parallel configuration of three Lyot filters, facilitated by a polarization beam splitter(PBS) for branch switching. The transmission properties of the filter are analyzed through theoretical modeling and experimental validation using the transmission matrix method. The experimental results are found to be consistent with the theoretical predictions, demonstrating the effectiveness of the proposed design. By adjusting the polarization controllers(PCs), the proposed laser can switch between wavelength spacings of 0.46 nm, 0.27 nm, and 0.76 nm, with a maximum optical signal-to-noise ratio(OSNR) of 38 d B. However, the stability of the laser with a 0.27 nm spacing is not high due to wavelength competition. Power fluctuation for 0.46 nm and 0.76 nm intervals is less than 0.93 d B and 0.78 d B in 1 h, with wavelength fluctuation less than 0.068 nm and 0.19 nm, respectively. This EDFL has the advantages of simple structure, great flexibility, and switchability, which can be applied to fiber optic sensing, wavelength division multiplexing(WDM) networks, and other fields that require a very flexible light source.展开更多
Deep eutectic solvents(DESs)have drawn considerable attention as a new type of green solvent since they were reported.Subsequent studies have shown that DESs have the potential to be used as“designable”solvents,whic...Deep eutectic solvents(DESs)have drawn considerable attention as a new type of green solvent since they were reported.Subsequent studies have shown that DESs have the potential to be used as“designable”solvents,which means that the precursors of DESs with different structures and properties can be screened to customize DESs for specific functions.Researchers have found that during the sample preparation process involving DESs,the specific properties of some“smart”DESs can be switched by directing external driving forces,leading to a reversible phase transition of the target solution.These"smart"DESs are called switchable deep eutectic solvents(SDESs).The advent of SDES simplifies the sample pretreatment steps,reduces the use of organic solvents,and makes solvents easy to recycle,which matches the concept of green and sustainable chemistry.Compared with the number of previous experimental studies,the reviews and summaries on SDESs are rare.Therefore,this review made a summary of the concept and research progress of SDESs based on some related works in the past decade,including composition and type,characterization,switching mechanism,etc.It is expected to provide a certain reference and guidance for the subsequent in-depth research of SDESs in the analytical sample pretreatment.展开更多
The fifth generation(5G)network communication systems operate in the millimeter waves and are expected to provide a much higher data rate in the multi-gigabit range,which is impossible to achieve using current wireles...The fifth generation(5G)network communication systems operate in the millimeter waves and are expected to provide a much higher data rate in the multi-gigabit range,which is impossible to achieve using current wireless services,including the sub-6 GHz band.In this work,we briefly review several existing designs of millimeter-wave phased arrays for 5G applications,beginning with the low-profile antenna array designs that either are fixed beam or scan the beam only in one plane.We then move on to array systems that offer two-dimensional(2D)scan capability,which is highly desirable for a majority of 5G applications.Next,in the main body of the paper,we discuss two different strategies for designing scanning arrays,both of which circumvent the use of conventional phase shifters to achieve beam scanning.We note that it is highly desirable to search for alternatives to conventional phase shifters in the millimeter-wave range because legacy phase shifters are both lossy and costly;furthermore,alternatives such as active phase shifters,which include radio frequency amplifiers,are both expensive and power-hungry.Given this backdrop,we propose two different antenna systems with potential for the desired 2D scan performance in the millimeter-wave range.The first of these is a Luneburg lens,which is excited either by a 2D waveguide array or by a microstrip patch antenna array to realize 2D scan capability.Next,for second design,we turn to phased-array designs in which the conventional phase shifter is replaced by switchable PIN diodes or varactor diodes,inserted between radiating slots in a waveguide to provide the desired phase shifts for scanning.Finally,we discuss several approaches to enhance the gain of the array by modifying the conventional array configurations.We describe novel techniques for realizing both one-dimensional(1D)and 2D scans by using a reconfigurable metasurface type of panels.展开更多
Here we developed a novel wavelength-switchable visible continuous-wave(CW)Pr^(3+):YLF laser around 670 nm.In single-wavelength laser operations,the maximum output powers of 2.60 W,1.26 W,and 0.21 W,the maximum slope ...Here we developed a novel wavelength-switchable visible continuous-wave(CW)Pr^(3+):YLF laser around 670 nm.In single-wavelength laser operations,the maximum output powers of 2.60 W,1.26 W,and 0.21 W,the maximum slope efficiencies of 34.7%,27.3%,and 12.3%were achieved with good beam qualities(M^(2)<1.6)at 670.4 nm,674.2 nm,and 678.9 nm,respectively.Record-high output power(2.6 W)and record-high slope efficiency(34.7%)were achieved for the Pr^(3+):YLF laser operation at 670.4 nm.This is also the first demonstration of longer-wavelength peaks beyond 670 nm in the^(3)P_(1)→^(3)F_(3)transition of Pr^(3+):YLF.In multi-wavelength laser operations,the dual-wavelength lasings,including 670.1/674.8 nm,670.1/679.1 nm,and 675.0/679.4 nm,were obtained by fine adjustment of one/two etalons within the cavity.Furthermore,the triple-wavelength lasings,e.g.672.2/674.2/678.6 nm and 670.4/674.8/679.4 nm,were successfully demonstrated.Moreover,both the first-order vortex lasers(LG_(0)^(+1)and LG_(0)^(-1)modes)at 670.4 nm were obtained by off-axis pumping.展开更多
Transfer printing based on switchable adhesive is essential for developing unconventional systems,including flexible electronics,stretchable electronics,and micro light-emitting diode(LED)displays.Here we report a des...Transfer printing based on switchable adhesive is essential for developing unconventional systems,including flexible electronics,stretchable electronics,and micro light-emitting diode(LED)displays.Here we report a design of switchable dry adhesive based on shape memory polymer(SMP)with hemispherical indenters,which offers a continuously tunable and reversible adhesion through the combination of the preloading effect and the thermal actuation of SMP.Experimental and numerical studies reveal the fundamental aspects of design,fabrication,and operation of the switchable dry adhesive.Demonstrations of this adhesive concept in transfer printing of flat objects(e.g.,silicon wafers),three-dimensional(3D)objects(e.g.,stainless steel balls),and rough objects(e.g.,frosted glasses)in two-dimensional(2D)or 3D layouts illustrate its unusual manipulation capabilities in heterogeneous material integration applications.展开更多
In this study, we developed a strategy for using the Scoggins procedure in the synthesis of acetamidines as novel C02-triggered switchable surfactants via acetimidates by effectively tuning the chemical equilibrium. T...In this study, we developed a strategy for using the Scoggins procedure in the synthesis of acetamidines as novel C02-triggered switchable surfactants via acetimidates by effectively tuning the chemical equilibrium. The as-synthesized N'-alkyl-N,Ndiethylacetamidines exhibit excellent CO_2/N_2 switchability and their bicarbonate salts have the ability to emulsify oil-water mixtures.展开更多
Reversible switching from a highly rough surface to another entirely smooth surface under external stimuli is crucial for intelligent materials applied in the fields of an ti-foggi ng,self-clea ning,oil-water separati...Reversible switching from a highly rough surface to another entirely smooth surface under external stimuli is crucial for intelligent materials applied in the fields of an ti-foggi ng,self-clea ning,oil-water separati on and biotech no logy.In this work,a thermal-responsive liquid crystal elastomer(LCE)surface covered with oriented micropillars is prepared via a facile two-step crosslinking method coupled with an extrusion molding program.The reversible change of topological structures of the LCE surface along with temperature is investigated by metallographic microscope,atomic force microscopy and optical con tact angle measuring system.At room temperature,the LCE sample is filled with plenty of micropillars with an average len gth of 8.76 pm,resulting in a super-hydrophobic surface with a water con tact angle(WCA)of 135°.When the temperature is in creased to above the cleari ng point,all the micropillars disappear,the LCE surface becomes entirely flat and presents a hydrophilic state with a WCA of 64°.The roughness-related wetting property of this microstructured LCE surface possesses good recyclability in several heating/cooling cycles.This work realizes a truly reversible transformation from a highly rough surface to an entirely smooth surface,and might promote the potential applications of this dynamic-responsive LCE surface in smart sensors and biomimetic control devices.展开更多
Responsive emulsions are the emulsions that can be reversibly switched on-demand between“stable”and“unstable”by environmental stimulus or trigger,which allows a simple and effective adjustment approach to achieve ...Responsive emulsions are the emulsions that can be reversibly switched on-demand between“stable”and“unstable”by environmental stimulus or trigger,which allows a simple and effective adjustment approach to achieve emulsification and demulsification.In recent years,stimuli-responsive emulsions acting as smart soft material are received considerable attention with the advantages of simple manipulation,good reversibility,low cost,easy treatment,and little effect on the system.In this paper,the recent research progress of emulsions that can respond to external stimuli,including pH,light,magnetic field,CO_(2)/N_(2) and dual responsive are reviewed.Also,the potential applications based on responsive emulsion are discussed,such as catalytic reactions,heavy oil recovery,polymer particles synthesis and optical sensor,aiming to summarize the latest achievements and put forward the possible development trends of responsive emulsions.展开更多
Designing a catalytic system that could convert cellulose to switchable C3 alcohols or esters with controllable selectivity is highly desired to meet the rapidly changing market demand.Herein,we develop RuSn catalysts...Designing a catalytic system that could convert cellulose to switchable C3 alcohols or esters with controllable selectivity is highly desired to meet the rapidly changing market demand.Herein,we develop RuSn catalysts with the altering Sn loadings that can achieve acetol formation from cellulose hydrogenation at240℃in presence of H_(2)or yield methyl lactate production from cellulose conversion in methanol and water mixture at 200℃in presence of N_(2).The increased Sn contents from 3%to 6%lead to form different surface sites from Ru_(3)Sn_(7),Ru,and SnO_(x)to Ru_(3)Sn_(7)and SnO_(x).The integrated Ru_(3)Sn_(7),Ru,and SnO_(x)species on 1.5%Ru-3%Sn/SiO_(2)catalyze isomerization,retro-aldol condensation,and hydrogenation individual steps with coordinated reaction rates,resulting in the acetol formation with a high yield of 53.7 C%.Furthermore,the optimum combination of Ru_(3)Sn_(7)and SnO_(x)on 1.5%Ru-6%Sn/SiO_(2)contributes to the isomerization,retro-aldol condensation,dehydration,and 1,2-hydride shift,giving rise to the preferential production of methyl lactate at a 25.1 C%yield.These results illustrate the feasibility of controlling the selective conversion of cellulose to C3 acetol or methyl lactate by devising a tunable catalytic system,which guides the rational design of catalysts for the selective conversion of cellulose.展开更多
This paper presents design and simulation of a switchable radiative cooler that exploits phase transition in vanadium di-oxide to turn on and off in response to temperature.The cooler consists of an emitter and a sola...This paper presents design and simulation of a switchable radiative cooler that exploits phase transition in vanadium di-oxide to turn on and off in response to temperature.The cooler consists of an emitter and a solar reflector separated by a spacer.The emitter and the reflector play a role of emitting energy in mid-infrared and blocking incoming solar energy in ultraviolet to near-infrared regime,respectively.Because of the phase transition of doped vanadium dioxide at room tem-perature,the emitter radiates its thermal energy only when the temperature is above the phase transition temperature.The feasibility of cooling is simulated using real outdoor conditions.We confirme that the switchable cooler can keep a desired temperature,despite change in environmental conditions.展开更多
基金financially supported by National Key R&D Program Young Scientists Project(No.2023YFC3903100)the National Natural Science Foundation of China(No.22322503)analytical and testing assistance from the Analysis and Testing Center of HUST。
文摘Switchable polymerization is emerging as a powerful tool to construct block copolymers directly from mixtures of monomers.However,current achievements typically iterate between two polymerization cycles to afford products with fixed sequences and compositions.Herein,we report the triethylborane/1,8-diazabicyclo[5.4.0]undec-7-ene(Et_3B/DBU)pair-mediated four-component switchable polymerization of propylene oxide(PO),CO_(2),phthalic anhydride(PA),and racemic lactide(rac-LA),which enables the on-demand synthesis of four different block copolymers,i.e.,poly(propylene phthalate)-b-polylactide(PPE-b-PLA),PPE-b-PLA-b-poly(propylene carbonate)(PPC),PPE-b-PPC-b-PLA,and PPE-b-PPCb-poly(propylene oxide)(PPO),through rationally modulating the Lewis pair(LP)ratio.Core to this protocol is that increasing the loading of Et_(3)B accelerates the ring-opening of PO while impeding the reactivity of rac-LA,thus allowing for fine-tuning of the thermodynamic and kinetic of the switchable polymerization.Therefore,the four polymerization cycles involving PO/PA ring-opening copolymerization(ROCOP),PO/CO_(2) ROCOP,rac-LA ring-opening polymerization(ROP),and PO ROP can be connected and discriminated in precisely programmed manners.
基金the financial support from the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB0470303)the National Key Research and Development Program of China (2022YFB4600101)+5 种基金the National Natural Science Foundation of China (52175201)the Research Program of Science and Technology Department of Gansu Province (24JRRA059, 24JRRA044, and 24YFFA014)the Science Fund of Shandong Laboratory of Advanced Materials and Green Manufacturing at Yantai (AMGM2024F12)the Major Program (ZYFZFX-2) of the Lanzhou Institute of Chemical Physics, CASthe Special Research Assistant Project of the Chinese Academy of Sciencesthe Oasis Scholar of Shihezi University
文摘Octopuses,due to their flexible arms,marvelous adaptability,and powerful suckers,are able to effortlessly grasp and disengage various objects in the marine surrounding without causing devastation.However,manipulating delicate objects such as soft and fragile foods underwater require gentle contact and stable adhesion,which poses a serious challenge to now available soft grippers.Inspired by the sucker infundibulum structure and flexible tentacles of octopus,herein we developed a hydraulically actuated hydrogel soft gripper with adaptive maneuverability by coupling multiple hydrogen bond-mediated supramolecular hydrogels and vat polymerization three-dimensional printing,in which hydrogel bionic sucker is composed of a tunable curvature membrane,a negative pressure cavity,and a pneumatic chamber.The design of the sucker structure with the alterable curvature membrane is conducive to realize the reliable and gentle switchable adhesion of the hydrogel soft gripper.As a proof-of-concept,the adaptive hydrogel soft gripper is capable of implement diversified underwater tasks,including gingerly grasping fragile foods like egg yolks and tofu,as well as underwater robots and vehicles that station-keeping and crawling based on switchable adhesion.This study therefore provides a transformative strategy for the design of novel soft grippers that will render promising utilities for underwater exploration soft robotics.
基金Financial support from the National Natural Science Foundation of China(52372289,52102368,52231007,12327804,T2321003,22088101,22178037 and U22A20424)Regional Joint Fund for Basic Research and Applied Basic Research of Guangdong Province(No.2020A1515110905)+1 种基金Guangdong Special Fund for key Areas(20237DZX3042)Shenzhen Stable Support Project,Liaoning Revitalization Talents Program(XLYC2002114)are highly appreciated.
文摘The synthesis of carbon supporter/nanoscale high-entropy alloys(HEAs)electromagnetic response composites by carbothermal shock method has been identified as an advanced strategy for the collaborative competition engineering of conductive/dielectric genes.Electron migration modes within HEAs as manipulated by the electronegativity,valence electron configurations and molar proportions of constituent elements determine the steady state and efficiency of equivalent dipoles.Herein,enlightened by skin-like effect,a reformative carbothermal shock method using carbonized cellulose paper(CCP)as carbon supporter is used to preserve the oxygencontaining functional groups(O·)of carbonized cellulose fibers(CCF).Nucleation of HEAs and construction of emblematic shell-core CCF/HEAs heterointerfaces are inextricably linked to carbon metabolism induced by O·.Meanwhile,the electron migration mode of switchable electronrich sites promotes the orientation polarization of anisotropic equivalent dipoles.By virtue of the reinforcement strategy,CCP/HEAs composite prepared by 35%molar ratio of Mn element(CCP/HEAs-Mn_(2.15))achieves efficient electromagnetic wave(EMW)absorption of−51.35 dB at an ultra-thin thickness of 1.03 mm.The mechanisms of the resulting dielectric properties of HEAs-based EMW absorbing materials are elucidated by combining theoretical calculations with experimental characterizations,which provide theoretical bases and feasible strategies for the simulation and practical application of electromagnetic functional devices(e.g.,ultra-wideband bandpass filter).
基金supported by the National Natural Science Foundation of China(No.52005475,62305321)the Natural Science Foundation of Anhui Province(No.JZ2024AKZR0561,2308085QE167)Opening Project of the Key Laboratory of Bionic Engineering(Ministry of Education),Jilin University(K202204).
文摘Smart windows(SWs)garner significant potential in green buildings owing to their capability of on-demand tuning the solar gains.Apart from solar regulation,people always desire a type of slippery SW which can repel the surface hydrous contaminants for anti-fouling application.Unfortunately,the up-to-date slippery SWs that respond to electrical/thermal stimuli have drawbacks of inferior durability and high energy-consumption,which greatly constrain their practical usability.This article presents our current work on an ultra-robust and energy-efficient near-infrared-responsive smart window(NIR-SW)which can regulate the optical transmittance and droplet’s adhesion in synergy.Significantly,laser-printing strategy enables us to seed the shape-memory photothermal microwalls on a transparent substrate,which can promote daylighting while maintaining privacy by near-infrared(NIR)switching between being transparent and opaque.As a light manipulator,it turns transparent with NIR-activated erect microwalls like an open louver;however,it turns opaque with the pressure-fixed bent microwalls akin to a closed louver.Simultaneously,the droplets can easily slip on the surface of erect microwalls similar to a classical lotus effect;by contrast,the droplets will tightly pin on the surface of bent microwalls analogous to the prevalent rose effect.Owing to shape-memory effect,this optical/wettability regulation is thus reversible and reconfigurable in response to the alternate NIR/pressure trigger.Moreover,NIR-SW unfolds a superior longevity despite suffering from the raindrop’s impacting more than 10000 cycles.Remarkably,such a new-type SW is competent for thermal management,anti-icing system,peep-proof screen,and programmable optics.This work renders impetus for the researchers striving for self-cleaning intelligent windows,energy-efficient greenhouse,and so forth.
基金financially supported by National Natural Science Foundation of China(No.22174129)the Natural Science Foundation of Zhejiang Province(No.LZY21E030001)the Xin-Miao Talents Program of Zhejiang Province(No.2024R403B064)。
文摘Green extraction of bioactive components from natural sources has been a hot topic in the field of chemistry and biology.As a kind of green solvents,deep eutectic solvents(DESs)have unique advantages in the extraction of bioactive substances.In recent years,as a new subgroup of DESs,the switchable deep eutectic solvents(SDESs)can realize reversible phase switching between hydrophobic and hydrophilic by external driving forces(CO_(2)/p H/temperature),allowing for the extraction of different polar components while avoiding the problem of difficult recovery of DESs.The application of SDESs reduces the consumption of large amounts of organic solvents during the extraction process,thereby promoting sustainability.In the meanwhile,it presents an advantage over traditional extraction methods in preserving product activity.Based on the recent researches on SDESs,this work summarized the composition,driving factors,and conversion mechanism of SDESs.The applications of SDESs in the extraction of natural products were primarily highlighted to provide a reference for future research.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Science and ICT(NRF-2022R1A2C2012243).
文摘In recent decades,brain tumors have emerged as a serious neurological disorder that often leads to death.Hence,Brain Tumor Segmentation(BTS)is significant to enable the visualization,classification,and delineation of tumor regions in Magnetic Resonance Imaging(MRI).However,BTS remains a challenging task because of noise,non-uniform object texture,diverse image content and clustered objects.To address these challenges,a novel model is implemented in this research.The key objective of this research is to improve segmentation accuracy and generalization in BTS by incorporating Switchable Normalization into Faster R-CNN,which effectively captures the fine-grained tumor features to enhance segmentation precision.MRI images are initially acquired from three online datasets:Dataset 1—Brain Tumor Segmentation(BraTS)2018,Dataset 2—BraTS 2019,and Dataset 3—BraTS 2020.Subsequently,the Switchable Normalization-based Faster Regions with Convolutional Neural Networks(SNFRC)model is proposed for improved BTS in MRI images.In the proposed model,Switchable Normalization is integrated into the conventional architecture,enhancing generalization capability and reducing overfitting to unseen image data,which is essential due to the typically limited size of available datasets.The network depth is increased to obtain discriminative semantic features that improve segmentation performance.Specifically,Switchable Normalization captures the diverse feature representations from the brain images.The Faster R-CNN model develops end-to-end training and effective regional proposal generation,with an enhanced training stability using Switchable Normalization,to perform an effective segmentation in MRI images.From the experimental results,the proposed model attains segmentation accuracies of 99.41%,98.12%,and 96.71%on Datasets 1,2,and 3,respectively,outperforming conventional deep learning models used for BTS.
基金sponsored by the National Natural Science Foundation of China(Grant Nos.52235007,T2121004,and 52325504)Key R&D Program of Zhejiang(Grant No.2024SSYS0027)。
文摘3D(three-dimensional)printing of soft/tough hydrogels has been widely used in flexible electronics,regenerative medicine,and other fields.However,due to their loose crosslinking,strong hydration and plasticizing effect of solvent(typically water)and susceptibility to swelling,the printed hydrogels always suffer from bearing compressive stress and shear stress.Here we report a 3D photo-printable hard/soft switchable hydrogel composite which is enabled by the phase transition(liquid/solid transition)of supercooled hydrated salt solution(solvents)within hydrogel.In hard status,it achieved a hardness of 86.5 Shore D(comparable to hard plastics),a compression strength of 81.7 MPa,and Young’s modulus of 1.2 GPa.These mechanical property parameters far exceed those of any currently 3D printed hydrogels.The most interesting thing is that the soft/hard states are easily switchable and this process can be repeated for many times.In the supercooled state,the random arrangement of liquid solvent molecules within hydrogels makes it as soft as conventional hydrogels.Upon artificial seeding of the crystal nucleus,the solvent in hydrogel undergoes rapid crystallization,resulting in the in-situ formation of numerous rigids,ordered rod-like nanoscale crystals uniformly embedded within the hydrogel matrix.This hierarchical structure remarkably enhances the Young’s modulus from kPa to GPa.Furthermore,the softness of hydrogel can be restored by heating and then cooling down to recover the supercooled state of the solvent.Taking advantage of soft/hard status switching,the hydrogel can conform to complex surface morphologies in its soft state and subsequently freeze that shape through crystallization,enabling rapid mold fabrication.Moreover,a shape fixation and recyclable smart hydrogel medical plaster bandage was also developed,capable of conforming the limb shapes and providing adequate support for the bone fracture patients after 10 min of crystallization.Our work suggests a bright future for the direct use of hard hydrogel as a robust industrial material.
基金supported by the National Natural Science Foundation of China(Grant No.52106099)the Natural Science Foundation of Shandong Province(Grant No.ZR2022YQ57)the Taishan Scholars Program。
文摘As a highly energy-efficient and sensitive radiation source,narrowband thermal emitters provide an ideal solution for non-contact gas detection,enabling the widespread application of mid-infrared“molecular fingerprint”technology.However,most narrowband thermal emitters lack reconfigurability,limiting their adaptability in practical applications.In this study,we propose a novel dual-band switchable narrowband thermal emitter in the mid-infrared region.The emitter consists of an aperiodic Ge/SiO_(2)/Ge/SiO_(2)(GSGS)structure and a phase change material In_(3)SbTe_(2)(IST).When IST is in the crystalline state,the emitter achieves narrowband emission peaks at wavelengths of 3.79μm and 6.12μm,corresponding to the“on”state.However,when IST transitions to the amorphous state,the dual-band high emission disappears and it features angle-and polarization-independent behavior,representing the“off”state.Furthermore,we verify the physical mechanism behind the high emission through phase and amplitude calculations as well as electric field distribution analysis.Notably,the introduction of the IST provides an additional degree of freedom for tunability.Furthermore,by adjusting the thickness of the spacer layer,the emitter can be precisely tuned to match the characteristic absorption peaks of various mid-infrared gases,such as CH_(4),CO_(2),CO,and NO,enabling multi-gas detection in mixed gas environments.The proposed thermal emitter serves as an effective and low-cost alternative for dual-band narrowband mid-infrared light sources,contributing to the advancement of multi-gas detection strategies.
基金the supports from Westlake Education Foundationthe support provided by the National Natural Science Foundation of China(Grant No.12304049)。
文摘We demonstrate that the sliding motion between two layers of the newly discovered ferroelectric and topologically trivial bismuth(Bi)monolayer[Nature 61767(2023)]can induce a sequence of topological phase transitions,alternating between Z_(2)trivial and nontrivial states.The lateral shift,while preserving spatial symmetry,can switch the quantum spin Hall state on and of.The sliding-induced changes in out-of-plane atomic buckling,which are directly coupled to in-plane ferroelectricity,are shown to signifcantly modulate the band gap and drive the topological phase transitions.We map out the topological phase diagram and in-plane ferroelectricity with respect to sliding displacements.With appropriate sliding,the bismuth bilayer can transition into a nontrivial polar metal,exhibiting a pronounced shift current response arising from interband geometric quantities of electronic bands.Moreover,bilayer Bi supports a sliding-tunable nonlinear anomalous Hall response resulting from the geometric Berry curvature dipole.Confgurations that are Z_(2)nontrivial can generate drastically different transverse currents orthogonal to the external electric feld,as both the direction and magnitude of the Berry curvature dipole at the Fermi level are highly sensitive to the sliding displacement.Our results suggest that bilayer bismuth,with its ability to generate multiple types of geometric currents,ofers a versatile platform for power-efcient“Berry slidetronics”for multistate memory applications integrating both band topology and ferroelectricity.
基金National Natural Science Foundation of China,Grant/Award Number:52003248Henan Province Youth Health Science and Technology Innovation Talent Training Program,Grant/Award Number:YQRC2023007+1 种基金Henan Province Excellent Youth Science Fund,Grant/Award Number:242300421064Joint Fund Predominant Discipline Cultivation Project of Henan Province,Grant/Award Number:232301420036.
文摘Switchable radiative cooling/heating holds great promise for mitigating the global energy and environmental crisis.Here,we reported a cost-effective,high-strength Janus film through surface optical engineering waste paper with one side decorated by a hydrophobic polymeric cooling coating consisting of micro/nanopore/particle hierarchical structure and the other side coated with hydrophilic MXene nanosheets for heating.The cooling surface demonstrates high solar reflectivity(96.3%)and infrared emissivity(95.5%),resulting in daytime/nighttime sub-ambient radiative cooling of 6℃/8℃with the theoretical cooling power of 100.6 and 138.5Wm^(−2),respectively.The heating surface exhibits high solar absorptivity(83.7%)and low infrared emissivity(15.2%),resulting in excellent radiative heating capacity for vehicle charging pile(~6.2℃)and solar heating performance.Impressively,the mechanical strength of Janus film increased greatly by 563%compared with that of pristine waste paper,which is helpful for its practical applications in various scenarios for switchable radiative thermal management through mechanical flipping.Energy-saving simulation results reveal that significant total energy savings of up to 32.4MJm^(−2) can be achieved annually(corresponding to the 12.4%saving ratio),showing the immense importance of reducing carbon footprint and promoting carbon neutrality.
基金supported by the Primary Research and Development Plan of Zhejiang Province (No.2023C03014)the Key Research and Development Program of Zhejiang Province (No.2022C03037)。
文摘This study presents the design of an erbium-doped fiber laser(EDFL) featuring switchable wavelength intervals achieved through the implementation of cascaded and parallel Lyot filters. The proposed laser system utilizes a cascaded and parallel configuration of three Lyot filters, facilitated by a polarization beam splitter(PBS) for branch switching. The transmission properties of the filter are analyzed through theoretical modeling and experimental validation using the transmission matrix method. The experimental results are found to be consistent with the theoretical predictions, demonstrating the effectiveness of the proposed design. By adjusting the polarization controllers(PCs), the proposed laser can switch between wavelength spacings of 0.46 nm, 0.27 nm, and 0.76 nm, with a maximum optical signal-to-noise ratio(OSNR) of 38 d B. However, the stability of the laser with a 0.27 nm spacing is not high due to wavelength competition. Power fluctuation for 0.46 nm and 0.76 nm intervals is less than 0.93 d B and 0.78 d B in 1 h, with wavelength fluctuation less than 0.068 nm and 0.19 nm, respectively. This EDFL has the advantages of simple structure, great flexibility, and switchability, which can be applied to fiber optic sensing, wavelength division multiplexing(WDM) networks, and other fields that require a very flexible light source.
基金financially supported by the National Natural Science Foundation of China(No.22174129)the Natural Science Foundation of Zhejiang Province(No.LZY21E030001)。
文摘Deep eutectic solvents(DESs)have drawn considerable attention as a new type of green solvent since they were reported.Subsequent studies have shown that DESs have the potential to be used as“designable”solvents,which means that the precursors of DESs with different structures and properties can be screened to customize DESs for specific functions.Researchers have found that during the sample preparation process involving DESs,the specific properties of some“smart”DESs can be switched by directing external driving forces,leading to a reversible phase transition of the target solution.These"smart"DESs are called switchable deep eutectic solvents(SDESs).The advent of SDES simplifies the sample pretreatment steps,reduces the use of organic solvents,and makes solvents easy to recycle,which matches the concept of green and sustainable chemistry.Compared with the number of previous experimental studies,the reviews and summaries on SDESs are rare.Therefore,this review made a summary of the concept and research progress of SDESs based on some related works in the past decade,including composition and type,characterization,switching mechanism,etc.It is expected to provide a certain reference and guidance for the subsequent in-depth research of SDESs in the analytical sample pretreatment.
文摘The fifth generation(5G)network communication systems operate in the millimeter waves and are expected to provide a much higher data rate in the multi-gigabit range,which is impossible to achieve using current wireless services,including the sub-6 GHz band.In this work,we briefly review several existing designs of millimeter-wave phased arrays for 5G applications,beginning with the low-profile antenna array designs that either are fixed beam or scan the beam only in one plane.We then move on to array systems that offer two-dimensional(2D)scan capability,which is highly desirable for a majority of 5G applications.Next,in the main body of the paper,we discuss two different strategies for designing scanning arrays,both of which circumvent the use of conventional phase shifters to achieve beam scanning.We note that it is highly desirable to search for alternatives to conventional phase shifters in the millimeter-wave range because legacy phase shifters are both lossy and costly;furthermore,alternatives such as active phase shifters,which include radio frequency amplifiers,are both expensive and power-hungry.Given this backdrop,we propose two different antenna systems with potential for the desired 2D scan performance in the millimeter-wave range.The first of these is a Luneburg lens,which is excited either by a 2D waveguide array or by a microstrip patch antenna array to realize 2D scan capability.Next,for second design,we turn to phased-array designs in which the conventional phase shifter is replaced by switchable PIN diodes or varactor diodes,inserted between radiating slots in a waveguide to provide the desired phase shifts for scanning.Finally,we discuss several approaches to enhance the gain of the array by modifying the conventional array configurations.We describe novel techniques for realizing both one-dimensional(1D)and 2D scans by using a reconfigurable metasurface type of panels.
基金supported by the National Natural Science Foundation of China(Nos.11674269,61975168).
文摘Here we developed a novel wavelength-switchable visible continuous-wave(CW)Pr^(3+):YLF laser around 670 nm.In single-wavelength laser operations,the maximum output powers of 2.60 W,1.26 W,and 0.21 W,the maximum slope efficiencies of 34.7%,27.3%,and 12.3%were achieved with good beam qualities(M^(2)<1.6)at 670.4 nm,674.2 nm,and 678.9 nm,respectively.Record-high output power(2.6 W)and record-high slope efficiency(34.7%)were achieved for the Pr^(3+):YLF laser operation at 670.4 nm.This is also the first demonstration of longer-wavelength peaks beyond 670 nm in the^(3)P_(1)→^(3)F_(3)transition of Pr^(3+):YLF.In multi-wavelength laser operations,the dual-wavelength lasings,including 670.1/674.8 nm,670.1/679.1 nm,and 675.0/679.4 nm,were obtained by fine adjustment of one/two etalons within the cavity.Furthermore,the triple-wavelength lasings,e.g.672.2/674.2/678.6 nm and 670.4/674.8/679.4 nm,were successfully demonstrated.Moreover,both the first-order vortex lasers(LG_(0)^(+1)and LG_(0)^(-1)modes)at 670.4 nm were obtained by off-axis pumping.
基金The authors acknowledge the supports of the National Natural Science Foundation of China(Grant Nos.11872331 and U20A6001)Zhejiang University K.P.Chao’s High Technology Development Foundation.
文摘Transfer printing based on switchable adhesive is essential for developing unconventional systems,including flexible electronics,stretchable electronics,and micro light-emitting diode(LED)displays.Here we report a design of switchable dry adhesive based on shape memory polymer(SMP)with hemispherical indenters,which offers a continuously tunable and reversible adhesion through the combination of the preloading effect and the thermal actuation of SMP.Experimental and numerical studies reveal the fundamental aspects of design,fabrication,and operation of the switchable dry adhesive.Demonstrations of this adhesive concept in transfer printing of flat objects(e.g.,silicon wafers),three-dimensional(3D)objects(e.g.,stainless steel balls),and rough objects(e.g.,frosted glasses)in two-dimensional(2D)or 3D layouts illustrate its unusual manipulation capabilities in heterogeneous material integration applications.
基金supported by the China National Petroleum Corporation (RIPED-2017-JS-87)
文摘In this study, we developed a strategy for using the Scoggins procedure in the synthesis of acetamidines as novel C02-triggered switchable surfactants via acetimidates by effectively tuning the chemical equilibrium. The as-synthesized N'-alkyl-N,Ndiethylacetamidines exhibit excellent CO_2/N_2 switchability and their bicarbonate salts have the ability to emulsify oil-water mixtures.
基金by the National Natural Science Foundation of China(Nos.21971037 and 51903048)Jiangsu Provincial Natural Science Foundation of China(No.BK20180406).
文摘Reversible switching from a highly rough surface to another entirely smooth surface under external stimuli is crucial for intelligent materials applied in the fields of an ti-foggi ng,self-clea ning,oil-water separati on and biotech no logy.In this work,a thermal-responsive liquid crystal elastomer(LCE)surface covered with oriented micropillars is prepared via a facile two-step crosslinking method coupled with an extrusion molding program.The reversible change of topological structures of the LCE surface along with temperature is investigated by metallographic microscope,atomic force microscopy and optical con tact angle measuring system.At room temperature,the LCE sample is filled with plenty of micropillars with an average len gth of 8.76 pm,resulting in a super-hydrophobic surface with a water con tact angle(WCA)of 135°.When the temperature is in creased to above the cleari ng point,all the micropillars disappear,the LCE surface becomes entirely flat and presents a hydrophilic state with a WCA of 64°.The roughness-related wetting property of this microstructured LCE surface possesses good recyclability in several heating/cooling cycles.This work realizes a truly reversible transformation from a highly rough surface to an entirely smooth surface,and might promote the potential applications of this dynamic-responsive LCE surface in smart sensors and biomimetic control devices.
基金supported by the National Natural Science Foun-dation of China(21908026)the Fujian Province science and tech-nology guidance project(2021Y0007)Key Program of Qingyuan Innovation Laboratory(00221004).
文摘Responsive emulsions are the emulsions that can be reversibly switched on-demand between“stable”and“unstable”by environmental stimulus or trigger,which allows a simple and effective adjustment approach to achieve emulsification and demulsification.In recent years,stimuli-responsive emulsions acting as smart soft material are received considerable attention with the advantages of simple manipulation,good reversibility,low cost,easy treatment,and little effect on the system.In this paper,the recent research progress of emulsions that can respond to external stimuli,including pH,light,magnetic field,CO_(2)/N_(2) and dual responsive are reviewed.Also,the potential applications based on responsive emulsion are discussed,such as catalytic reactions,heavy oil recovery,polymer particles synthesis and optical sensor,aiming to summarize the latest achievements and put forward the possible development trends of responsive emulsions.
基金supported by“the Research Funds of Happiness Flower ECNU”(2019ST2101)。
文摘Designing a catalytic system that could convert cellulose to switchable C3 alcohols or esters with controllable selectivity is highly desired to meet the rapidly changing market demand.Herein,we develop RuSn catalysts with the altering Sn loadings that can achieve acetol formation from cellulose hydrogenation at240℃in presence of H_(2)or yield methyl lactate production from cellulose conversion in methanol and water mixture at 200℃in presence of N_(2).The increased Sn contents from 3%to 6%lead to form different surface sites from Ru_(3)Sn_(7),Ru,and SnO_(x)to Ru_(3)Sn_(7)and SnO_(x).The integrated Ru_(3)Sn_(7),Ru,and SnO_(x)species on 1.5%Ru-3%Sn/SiO_(2)catalyze isomerization,retro-aldol condensation,and hydrogenation individual steps with coordinated reaction rates,resulting in the acetol formation with a high yield of 53.7 C%.Furthermore,the optimum combination of Ru_(3)Sn_(7)and SnO_(x)on 1.5%Ru-6%Sn/SiO_(2)contributes to the isomerization,retro-aldol condensation,dehydration,and 1,2-hydride shift,giving rise to the preferential production of methyl lactate at a 25.1 C%yield.These results illustrate the feasibility of controlling the selective conversion of cellulose to C3 acetol or methyl lactate by devising a tunable catalytic system,which guides the rational design of catalysts for the selective conversion of cellulose.
基金financially supported by the Green Science program funded by POSCOthe National Research Foundation(NRF)grants(NRF2019R1A2C3003129,CAMM-2019M3A6B3030637,NRF-2019R1A5A8080290,and NRF-2018M3D1A1058997)funded by the Ministry of Science and ICT,Republic of Korea+2 种基金the Global Ph.D.fellowship(NRF-2017H1A2A1043204)from the Ministry of Education,Republic of Koreathe PIURI fellowship funded by POSTECHa fellowship from Hyundai Motor Chung Mong-Koo Foundation。
文摘This paper presents design and simulation of a switchable radiative cooler that exploits phase transition in vanadium di-oxide to turn on and off in response to temperature.The cooler consists of an emitter and a solar reflector separated by a spacer.The emitter and the reflector play a role of emitting energy in mid-infrared and blocking incoming solar energy in ultraviolet to near-infrared regime,respectively.Because of the phase transition of doped vanadium dioxide at room tem-perature,the emitter radiates its thermal energy only when the temperature is above the phase transition temperature.The feasibility of cooling is simulated using real outdoor conditions.We confirme that the switchable cooler can keep a desired temperature,despite change in environmental conditions.
