Traffic congestion plays a significant role in intelligent transportation systems(ITS)due to rapid urbanization and increased vehicle concentration.The congestion is dependent on multiple factors,such as limited road ...Traffic congestion plays a significant role in intelligent transportation systems(ITS)due to rapid urbanization and increased vehicle concentration.The congestion is dependent on multiple factors,such as limited road occupancy and vehicle density.Therefore,the transportation system requires an effective prediction model to reduce congestion issues in a dynamic environment.Conventional prediction systems face difficulties in identifying highly congested areas,which leads to reduced prediction accuracy.The problem is addressed by integrating Graph Neural Networks(GNN)with the Lion Swarm Optimization(LSO)framework to tackle the congestion prediction problem.Initially,the traffic information is collected and processed through a normalization process to scale the data and mitigate issues of overfitting and high dimensionality.Then,the traffic flow and temporal characteristic features are extracted to identify the connectivity of the road segment.From the connectivity and node relationship graph,modeling improves the overall prediction accuracy.During the analysis,the lion swarm optimization process utilizes the concepts of exploration and exploitation to understand the complex traffic dependencies,which helps predict high congestion on roads with minimal deviation errors.There are three core optimization phases:roaming,hunting,and migration,which enable the framework to make dynamic adjustments to enhance the predictions.The framework’s efficacy is evaluated using benchmark datasets,where the proposed work achieves 99.2%accuracy and minimizes the prediction deviation value by up to 2.5%compared to other methods.With the new framework,there was a more accurate prediction of realtime congestion,lower computational cost,and improved regulation of traffic flow.This system is easily implemented in intelligent transportation systems,smart cities,and self-driving cars,providing a robust and scalable solution for future traffic management.展开更多
Acetone,as widely used reagents in industry and laboratories,are extremely harmful to the human.So the detection of acetone gas concentrations and leaks in special environments at room temperature is essential.Herein,...Acetone,as widely used reagents in industry and laboratories,are extremely harmful to the human.So the detection of acetone gas concentrations and leaks in special environments at room temperature is essential.Herein,the nanocomposite combining SnO-SnO_(2)(p-n junction)and Ti_(3)C_(2)T_(x) MXene was successfully synthesized by a one-step hydrothermal method.Because of the existence of a small amount of oxygen during the hydrothermal conditions,part of the p-type SnO was oxidized to n-type SnO_(2),forming in-situ p-n junctions on the surface of Sn O.The hamburger-like SnO-SnO_(2)/Ti_(3)C_(2)T_(x) sensor exhibited improved acetone gas sensing response of 12.1(R_(g)/R_(a))at room temperature,which were nearly 11 and 4 times higher than those of pristine Ti_(3)C_(2)T_(x) and pristine SnO-SnO_(2),respectively.Moreover,it expressed a short recovery time(9 s)and outstanding reproducibility.Because of the different work functions,the Schottky barrier was formed between the SnO and the Ti_(3)C_(2)T_(x) nanosheets,acting as a hole accumulation layer(HALs)between Ti_(3)C_(2)T_(x) and tin oxides.Herein,the sensing mechanism based on the formation of hetero-junctions and high conductivity of the metallic phase of Ti_(3)C_(2)T_(x) MXene in SnO-SnO_(2)/Ti_(3)C_(2)T_(x) sensors was discussed in detail.展开更多
With the development in next-generation semiconductor power devices,the power devices based on silicon carbide(SiC)and gallium nitride(GaN)are expected to replace the traditional Si-based power devices[1–6].However,t...With the development in next-generation semiconductor power devices,the power devices based on silicon carbide(SiC)and gallium nitride(GaN)are expected to replace the traditional Si-based power devices[1–6].However,the foreseeable harsh operating environment such as heavy thermal-load or extremely temperature cycle required more reliable interconnection technology[4,7-9].展开更多
Syzygium campanulatum Korth is a plant, which is a rich source of secondary metabolites （especially flavanones, chalcone, and triterpenoids）. In our present study, three conventional solvent extraction （CSE） techn...Syzygium campanulatum Korth is a plant, which is a rich source of secondary metabolites （especially flavanones, chalcone, and triterpenoids）. In our present study, three conventional solvent extraction （CSE） techniques and supercritical fluid extraction （SFE） techniques were performed to achieve a maximum recovery of two flavanones, chalcone, and two triterpenoids from S. campanulatum leaves. Furthermore, a Box-Behnken design was constructed for the SFE technique using pressure, temperature, and particle size as independent variables, and yields of crude extract, individual and total secondary metabolites as the dependent variables. In the CSE procedure, twenty extracts were produced using ten different solvents and three techniques （maceration, soxhletion, and reflux）. An enriched extract of five secondary metabolites was collected using n-hexane：methanol （1：1） soxhletion. Using food-grade ethanol as a modifier, the SFE methods produced a higher recovery （25.5%-84.9%） of selected secondary metabo- lites as compared to the CSE techniques （0.92%-66.00%）.展开更多
The laser induced plasma dynamics of graphite material are investigated by optical emission spectroscopy. Abla- tion and excitation of the graphite material is performed by using an 1064nm Nd：YAG laser in different a...The laser induced plasma dynamics of graphite material are investigated by optical emission spectroscopy. Abla- tion and excitation of the graphite material is performed by using an 1064nm Nd：YAG laser in different ambient pressures. Characteristics of graphite spectra as line intensity variations and signal-to-noise ratio are presented with a main focus on the influence of the ambient pressure on the interaction of laser-induced graphite plasma with an ambient environment. Atomic emission lines are utilized to investigate the dynamical behavior of plasma, such as the excitation temperature and electron density, to describe emission differences under different ambient conditions. The excitation temperature and plasma electron density are the primary factors which contribute to the differences among the atomic carbon emission at different ambient pressures. Reactions between the plasma species and ambient gas, and the total molecular number are the main factors influencing molecular carbon emis- sion. The influence of laser energy on the plasma interaction with environment is also investigated to demonstrate the dynamical behavior of carbon species so that it can be utilized to optimize plasma fluctuations.展开更多
The complexation behaviors of anthracenecarboxylic acid and water-soluble cationic pillararenes have been investigated by 1H NMR,UV-vis and ITC methods.The cationic pillar[6]arene was found to stepwise form 1：1 and 1...The complexation behaviors of anthracenecarboxylic acid and water-soluble cationic pillararenes have been investigated by 1H NMR,UV-vis and ITC methods.The cationic pillar[6]arene was found to stepwise form 1：1 and 1：2 complexes,having a large K1 and a relatively small K2 values.Photocyclodimerization of AC within the pillar[6]arene improved the yield of the head-to-head photodimers.Up to 4.97 HH/HT ratio has been reached by optimizing the reaction conditions.展开更多
Photochromic diarylethenes were deemed to be one of the most promising molecular building blocks tot photoresponsive materials. This review gives a brief summary to the recent progress of studies of diarylethenes in s...Photochromic diarylethenes were deemed to be one of the most promising molecular building blocks tot photoresponsive materials. This review gives a brief summary to the recent progress of studies of diarylethenes in supramolecular systems, focusing on their applications in biological systems, photoresponsive mechanical materials and photoresponsive chemosensors. ~ 2015 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.展开更多
Phenol is considered as pollutant due to its toxicity and carcinogenic effect.Thus,variety of innovative methods for separation and recovery of phenolic compounds is developed in order to remove the unwanted phenol fr...Phenol is considered as pollutant due to its toxicity and carcinogenic effect.Thus,variety of innovative methods for separation and recovery of phenolic compounds is developed in order to remove the unwanted phenol from wastewater and obtain valuable phenolic compound.One of potential method is extraction using green based liquid organic solvent.Therefore,the feasibility of using palm oil was investigated.In this research,palm oil based organic phase was used as diluents to treat a simulated wastewater containing 300×10^(-6) of phenol solution using emulsion liquid membrane process(ELM).The stability of water-in-oil(W/O) emulsion on diluent composition and the parameters affecting the phenol removal efficiency and stability of the emulsion;such as emulsification speed,emulsification time,agitation speed,surfactant concentration,pH of external phase,contact time,stripping agent concentration and treat ratio were carried out.The results of ELM study showed that at ratio7 to 3 of palm oil to kerosene,5 min and 1300 r·min^(-1) of emulsification process the stabile primary emulsion were formed.Also,no carrier is needed to facilitate the phenol extraction.In experimental conditions of500 r·min^(-1) of agitation speed,3%Span 80,pH 8 of external phase,5 min of contact time,0.1 mol·L^(-1) NaOH as stripping agent and 1:10 of treat ratio,the ELM process was very promising for removing the phenol from the wastewater.The extraction performance at about 83%of phenol was removed for simulated wastewater and an enrichment of phenol in recovery phase as phenolate compound was around 11 times.展开更多
Four pillar[5]arene-based bicyclic compounds,so-called molecular universal joint(MUJ),were synthesized by incorporating a bisamide ring containing N,O,or S-heteroatom groups,which served as stimuli-responsive chiropti...Four pillar[5]arene-based bicyclic compounds,so-called molecular universal joint(MUJ),were synthesized by incorporating a bisamide ring containing N,O,or S-heteroatom groups,which served as stimuli-responsive chiroptical molecular devices.The structure of MUJ was confirmed by 1H NMR spectra and single-crystal X-ray diffraction analysis,and their planar-chiral enantiomers were successfully separated.Chiroptical inversion behaviors from in to out configurations triggered by temperature,solvent,and vip complexation were investigated by circular dichroism spectra.Chiroptical inversion could be realized in the presence of adiponitrile in certain solvents due to the solvation effects on the side ring and the threading of the vip into the pillar[5]arene cavity.However,the stronger self-included interactions between the cavity and the inside ring of certain MUJs led to inhibition of the switching.展开更多
Several cyclodextrin-cucurbit[6]uril-cowheeled [4]rotaxanes were synthesized through the cucurbit[6]uril-templated azide-alkyne 1,3-dipolar cycloaddition. The intramolecular interaction between the aromatic axle and t...Several cyclodextrin-cucurbit[6]uril-cowheeled [4]rotaxanes were synthesized through the cucurbit[6]uril-templated azide-alkyne 1,3-dipolar cycloaddition. The intramolecular interaction between the aromatic axle and the capping groups of cyclodextrin moieties was investigated by UV-vis, fluorescence,circular dichroism and NMR spectroscopic studies. The rotational kinetic of the wheel around the axle can be manipulated by adjusting the temperature. The capping group apparently slowed down the rotation of the wheel, playing a role of the brake, and lowering the temperature can stop the rotation of the wheel on the NMR timescale.展开更多
While extensive research has explored manipulating supramolecular chirality through internal and external factors,the specific solvation effect remains uncharted territory.This study synthesized ortho-functionalized p...While extensive research has explored manipulating supramolecular chirality through internal and external factors,the specific solvation effect remains uncharted territory.This study synthesized ortho-functionalized pillar[5]arene(P[5])derivatives Mn and Dn via thiol-Michael addition,characterizing them through spectroscopic and X-ray single-crystal analyses.Mn and Dn interacted with chiral amines,yielding significant circular dichroism(CD)responses.Intriguingly,the chiral induction exhibited pronounced specific solvation effects,where achiral alcohols either enhanced,attenuated,or reversed CD signals.Testing over 40 alcohols revealed correlations between the specific solvation effects and alcohol polarity and acidity.Molecular dynamics simulations unveiled that the alcohol interacted distinctly through hydrogen bonding,with one ion pair bonding up to four alcohol molecules.The Rp-and Sp-preference of the P[5]core could be altered by the number of bonded alcohols.This work uncovers the critical role of alcohol-specific solvation in ion pair-involved chiral assembly,pertinent for asymmetric ion-pairing catalysis and the use of alcohol additives in organic solvents.展开更多
Nonlinearity in parallel compliance can be exploited to improve the performance of locomotion systems in terms of(1)energy efficiency,(2)control robustness,and(3)gait optimality;that is,attaining energy efficiency acr...Nonlinearity in parallel compliance can be exploited to improve the performance of locomotion systems in terms of(1)energy efficiency,(2)control robustness,and(3)gait optimality;that is,attaining energy efficiency across a set of motions.Thus far,the literature has investigated and validated only the first two benefits.In this study,we present a new mathematical framework for designing nonlinear compliances in cyclic tasks encompassing all three benefits.We present an optimization-based formulation for each benefit to obtain the desired compliance profile.Furthermore,we analytically prove that,compared to linear compliance,using nonlinear compliance leads to(1)lower energy consumption,(2)better closed-loop performance,specifically in terms of tracking error,and(3)a higher diversity of natural frequencies.To compare the performance of linear and nonlinear compliance,we apply the proposed methods to a diverse set of robotic systems performing cyclic tasks,including a 2-DOF manipulator,a 3-DOF bipedal walker,and a hopper model.Compared to linear compliance,the nonlinear compliance leads to better performance in all aspects;for example,a 70%reduction in energy consumption and tracking error for the manipulator simulation.Regarding gait optimality,for all robotic simulation models,compared to linear compliance,the nonlinear compliance has lower energy consumption and tracking error over the considered set of motions.The proposed analytical studies and simulation results strongly support the idea that using nonlinear compliance significantly improves robotic system performance in terms of energy efficiency,control robustness,and gait optimality.展开更多
Silver nanowires （AgNWs） surrounded by insulating poly（vinylpyrrolidone） have been synthesized by a polyol process and employed as transparent electrodes. The AgNW transparent electrodes can be fabricated by heatt...Silver nanowires （AgNWs） surrounded by insulating poly（vinylpyrrolidone） have been synthesized by a polyol process and employed as transparent electrodes. The AgNW transparent electrodes can be fabricated by heattreatment at about 200 ℃ which forms connecting junctions between AgNWs. Such a heating process is, however, one of the drawbacks of the fabrication of AgNW electrodes on heat-sensitive substrates. Here it has been demonstrated that the electrical conductivity of AgNW electrodes can be improved by mechanical pressing at 25 MPa for 5 s at room temperature. This simple process results in a low sheet resistance of 8.6 Ω/square and a transparency of 80.0%, equivalent to the properties of the AgNW electrodes heated at 200 ℃. This technique makes it possible to fabricate AgNW transparent electrodes on heat-sensitive substrates. The AgNW electrodes on poly（ethylene terephthalate） films exhibited high stability of their electrical conductivities against the repeated bending test. In addition, the surface roughness of the pressed AgNW electrodes is one-third of that of the heat-treated electrode because the AgNW junctions are mechanically compressed. As a result, an organic solar cell fabricated on the pressed AgNW electrodes exhibited a power conversion as much as those fabricated on indium tin oxide electrodes. These findings enable continuous roll-to-roll processing at room temperature, resulting in relatively simple, inexpensive, and scalable processing that is suitable for forthcoming technologies such as organic solar cells, flexible displays, and touch screens.展开更多
Si3N4/BN nanocomposite powders with the mi-crostructure of the micro-sized a-Si3N4 particles coated with nano-sized BN particles were synthesized via the chemical reaction of boric acid, urea, and a-Si3N4 powder in a ...Si3N4/BN nanocomposite powders with the mi-crostructure of the micro-sized a-Si3N4 particles coated with nano-sized BN particles were synthesized via the chemical reaction of boric acid, urea, and a-Si3N4 powder in a hydro-gen gas. The results of XRD, TEM, and selected area elec-tron diffraction showed that amorphous BN and a little amount of turbostratic BN(t-BN) were coated on Si3N4 parti-cles as the second phase after reaction at 1100℃. After re-heating the composite powders at 1450℃ in a nitrogen gas, the amorphous and turbostratic BN is transformed into h-BN. These nanocomposite powders can be used to prepare Si3N4/BN ceramic composites by hot-pressing at 1800℃, which have perfect machinability and can be drilled with normal metal tools.展开更多
In this work, we have evaluated the biosensing capability of the porous silicon （PSi） based sidewall Bragg-grating resonator. The approximation of the quasi-TE mode full vector for the eigenmode calculation is perfo...In this work, we have evaluated the biosensing capability of the porous silicon （PSi） based sidewall Bragg-grating resonator. The approximation of the quasi-TE mode full vector for the eigenmode calculation is performed using a full vector mode solver. The transmission spectra of the device are evaluated using the transfer matrix method. We have observed a shift in the resonant band for a change in the refractive index of biomaterial in the upper cladding region. The theoretical value of the bulk sensitivity is calculated to be 387.48nm/RIU. The device is suitable for biosensing application due to its ability of interacting signal with the infiltrated analytes in the PSi waveguide core.展开更多
Several novel macrocyclic arenes that are composed of six indole subunits,so-called bisindole[3]arenes(BID[3]s),were conveniently synthesized by the aluminum trichloride-catalyzed one-pot condensation of bisindole der...Several novel macrocyclic arenes that are composed of six indole subunits,so-called bisindole[3]arenes(BID[3]s),were conveniently synthesized by the aluminum trichloride-catalyzed one-pot condensation of bisindole derivatives and paraformaldehyde in dichloromethane at room temperature.Their macrocyclic structures were demonstrated by X-ray single-crystal studies,and the presence of the macrocyclic cavities made it possible to accommodate specific small organic molecules.The BID[3]s have exceptionally high iodine adsorption ability due to the strong and synergic interaction of indole units toward iodine,exhibiting significant morphology changes upon adsorption and desorption of iodine.Iodine uptake capacity of up to 5.12 g·g^(−1) was found with MeBID[3],which is the highest value ever reported for macrocyclic arenes.展开更多
Purpose–The purpose of this paper is to propose a method to avoid hyperstaticity and eventually reduce the magnitude of undesired force/torques.The authors also study the influence of hyperstaticity on human motor co...Purpose–The purpose of this paper is to propose a method to avoid hyperstaticity and eventually reduce the magnitude of undesired force/torques.The authors also study the influence of hyperstaticity on human motor control during a redundant task.Design/methodology/approach–Increasing the level of transparency of robotic interfaces is critical to haptic investigations and applications.This issue is particularly important to robotic structures that mimic the human counterpart’s morphology and attach directly to the limb.Problems arise for complex joints such as the wrist,which cannot be accurately matched with a traditional mechanical joint.In such cases,mechanical differences between human and robotic joint cause hyperstaticity(i.e.over-constrained)which,coupled with kinematic misalignment,leads to uncontrolled force/torque at the joint.This paper focusses on the prono-supination(PS)degree of freedom of the forearm.The overall force and torque in the wrist PS rotation is quantified by means of a wrist robot.Findings–A practical solution to avoid hyperstaticity and reduce the level of undesired force/torque in the wrist is presented.This technique is shown to reduce 75 percent of the force and 68 percent of the torque.It is also shown an over-constrained mechanism could alter human motor strategies.Practical implications–The presented solution could be taken into account in the early phase of design of robots.It could also be applied to modify the fixation points of commercial robots in order to reduce the magnitude of reaction forces and avoid changes in motor strategy during the robotic therapy.Originality/value–In this paper for the first time the authors study the effect of hyperstaticity on both reaction forces and human motor strategies.展开更多
基金Deanship of Graduate Studies and Scientific Research at Jouf University under grant No.(DGSSR-2025-02-01641)。
文摘Traffic congestion plays a significant role in intelligent transportation systems(ITS)due to rapid urbanization and increased vehicle concentration.The congestion is dependent on multiple factors,such as limited road occupancy and vehicle density.Therefore,the transportation system requires an effective prediction model to reduce congestion issues in a dynamic environment.Conventional prediction systems face difficulties in identifying highly congested areas,which leads to reduced prediction accuracy.The problem is addressed by integrating Graph Neural Networks(GNN)with the Lion Swarm Optimization(LSO)framework to tackle the congestion prediction problem.Initially,the traffic information is collected and processed through a normalization process to scale the data and mitigate issues of overfitting and high dimensionality.Then,the traffic flow and temporal characteristic features are extracted to identify the connectivity of the road segment.From the connectivity and node relationship graph,modeling improves the overall prediction accuracy.During the analysis,the lion swarm optimization process utilizes the concepts of exploration and exploitation to understand the complex traffic dependencies,which helps predict high congestion on roads with minimal deviation errors.There are three core optimization phases:roaming,hunting,and migration,which enable the framework to make dynamic adjustments to enhance the predictions.The framework’s efficacy is evaluated using benchmark datasets,where the proposed work achieves 99.2%accuracy and minimizes the prediction deviation value by up to 2.5%compared to other methods.With the new framework,there was a more accurate prediction of realtime congestion,lower computational cost,and improved regulation of traffic flow.This system is easily implemented in intelligent transportation systems,smart cities,and self-driving cars,providing a robust and scalable solution for future traffic management.
基金supported financially by the National Natural Science Foundation of China(Nos.,51572158 and 51972200)the Graduate Innovation Fund of Shaanxi University of Science&Technology+2 种基金funded by the Japan Society for the Promotion of Science(JSPS)Grant-in-Aid for the Scientific Research(KAKENHI Nos.20H00297 and Innovative Area“Mixed Anion”(No.16H06439))the Nippon Sheet Glass Foundation for Materials Science and Engineeringby the Dynamic Alliance for Open Innovations Bridging Human,Environment and Materials,the Cooperative Research Program of“Network Joint Research Center for Materials and Devices”。
文摘Acetone,as widely used reagents in industry and laboratories,are extremely harmful to the human.So the detection of acetone gas concentrations and leaks in special environments at room temperature is essential.Herein,the nanocomposite combining SnO-SnO_(2)(p-n junction)and Ti_(3)C_(2)T_(x) MXene was successfully synthesized by a one-step hydrothermal method.Because of the existence of a small amount of oxygen during the hydrothermal conditions,part of the p-type SnO was oxidized to n-type SnO_(2),forming in-situ p-n junctions on the surface of Sn O.The hamburger-like SnO-SnO_(2)/Ti_(3)C_(2)T_(x) sensor exhibited improved acetone gas sensing response of 12.1(R_(g)/R_(a))at room temperature,which were nearly 11 and 4 times higher than those of pristine Ti_(3)C_(2)T_(x) and pristine SnO-SnO_(2),respectively.Moreover,it expressed a short recovery time(9 s)and outstanding reproducibility.Because of the different work functions,the Schottky barrier was formed between the SnO and the Ti_(3)C_(2)T_(x) nanosheets,acting as a hole accumulation layer(HALs)between Ti_(3)C_(2)T_(x) and tin oxides.Herein,the sensing mechanism based on the formation of hetero-junctions and high conductivity of the metallic phase of Ti_(3)C_(2)T_(x) MXene in SnO-SnO_(2)/Ti_(3)C_(2)T_(x) sensors was discussed in detail.
文摘With the development in next-generation semiconductor power devices,the power devices based on silicon carbide(SiC)and gallium nitride(GaN)are expected to replace the traditional Si-based power devices[1–6].However,the foreseeable harsh operating environment such as heavy thermal-load or extremely temperature cycle required more reliable interconnection technology[4,7-9].
文摘Syzygium campanulatum Korth is a plant, which is a rich source of secondary metabolites （especially flavanones, chalcone, and triterpenoids）. In our present study, three conventional solvent extraction （CSE） techniques and supercritical fluid extraction （SFE） techniques were performed to achieve a maximum recovery of two flavanones, chalcone, and two triterpenoids from S. campanulatum leaves. Furthermore, a Box-Behnken design was constructed for the SFE technique using pressure, temperature, and particle size as independent variables, and yields of crude extract, individual and total secondary metabolites as the dependent variables. In the CSE procedure, twenty extracts were produced using ten different solvents and three techniques （maceration, soxhletion, and reflux）. An enriched extract of five secondary metabolites was collected using n-hexane：methanol （1：1） soxhletion. Using food-grade ethanol as a modifier, the SFE methods produced a higher recovery （25.5%-84.9%） of selected secondary metabo- lites as compared to the CSE techniques （0.92%-66.00%）.
基金Supported by the FRGS under Grant No R.J130000.7809.4F519
文摘The laser induced plasma dynamics of graphite material are investigated by optical emission spectroscopy. Abla- tion and excitation of the graphite material is performed by using an 1064nm Nd：YAG laser in different ambient pressures. Characteristics of graphite spectra as line intensity variations and signal-to-noise ratio are presented with a main focus on the influence of the ambient pressure on the interaction of laser-induced graphite plasma with an ambient environment. Atomic emission lines are utilized to investigate the dynamical behavior of plasma, such as the excitation temperature and electron density, to describe emission differences under different ambient conditions. The excitation temperature and plasma electron density are the primary factors which contribute to the differences among the atomic carbon emission at different ambient pressures. Reactions between the plasma species and ambient gas, and the total molecular number are the main factors influencing molecular carbon emis- sion. The influence of laser energy on the plasma interaction with environment is also investigated to demonstrate the dynamical behavior of carbon species so that it can be utilized to optimize plasma fluctuations.
基金supported by the grants from National Natural Science Foundation of China (Nos. 21372165, 21321061 and 21572142 for CY, No. 21402129 for WW)State Key Laboratory of Polymer Materials Engineering (No. sklpme2014-2-06)
文摘The complexation behaviors of anthracenecarboxylic acid and water-soluble cationic pillararenes have been investigated by 1H NMR,UV-vis and ITC methods.The cationic pillar[6]arene was found to stepwise form 1：1 and 1：2 complexes,having a large K1 and a relatively small K2 values.Photocyclodimerization of AC within the pillar[6]arene improved the yield of the head-to-head photodimers.Up to 4.97 HH/HT ratio has been reached by optimizing the reaction conditions.
基金the National Natural Science Foundation of China (Nos. 21372165, 21321061 and 21402129)State Key Laboratory of Polymer Materials Engineering (No. sklpme20142-06)Comprehensive Training Platform of Specialized Laboratory, College of Chemistry, Sichuan University for financial support
文摘Photochromic diarylethenes were deemed to be one of the most promising molecular building blocks tot photoresponsive materials. This review gives a brief summary to the recent progress of studies of diarylethenes in supramolecular systems, focusing on their applications in biological systems, photoresponsive mechanical materials and photoresponsive chemosensors. ~ 2015 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.
基金Supported by the Ministry of Higher Education(MOHE)Universiti Teknologi Malaysia(RU Research GrantGUP:Q.J130000.2546.12H50)
文摘Phenol is considered as pollutant due to its toxicity and carcinogenic effect.Thus,variety of innovative methods for separation and recovery of phenolic compounds is developed in order to remove the unwanted phenol from wastewater and obtain valuable phenolic compound.One of potential method is extraction using green based liquid organic solvent.Therefore,the feasibility of using palm oil was investigated.In this research,palm oil based organic phase was used as diluents to treat a simulated wastewater containing 300×10^(-6) of phenol solution using emulsion liquid membrane process(ELM).The stability of water-in-oil(W/O) emulsion on diluent composition and the parameters affecting the phenol removal efficiency and stability of the emulsion;such as emulsification speed,emulsification time,agitation speed,surfactant concentration,pH of external phase,contact time,stripping agent concentration and treat ratio were carried out.The results of ELM study showed that at ratio7 to 3 of palm oil to kerosene,5 min and 1300 r·min^(-1) of emulsification process the stabile primary emulsion were formed.Also,no carrier is needed to facilitate the phenol extraction.In experimental conditions of500 r·min^(-1) of agitation speed,3%Span 80,pH 8 of external phase,5 min of contact time,0.1 mol·L^(-1) NaOH as stripping agent and 1:10 of treat ratio,the ELM process was very promising for removing the phenol from the wastewater.The extraction performance at about 83%of phenol was removed for simulated wastewater and an enrichment of phenol in recovery phase as phenolate compound was around 11 times.
基金the National Natural Science Foundation of China(Nos.92056116,21871194,21971169)National Key Research and Development Program of China(No.2017YFA0505903).
文摘Four pillar[5]arene-based bicyclic compounds,so-called molecular universal joint(MUJ),were synthesized by incorporating a bisamide ring containing N,O,or S-heteroatom groups,which served as stimuli-responsive chiroptical molecular devices.The structure of MUJ was confirmed by 1H NMR spectra and single-crystal X-ray diffraction analysis,and their planar-chiral enantiomers were successfully separated.Chiroptical inversion behaviors from in to out configurations triggered by temperature,solvent,and vip complexation were investigated by circular dichroism spectra.Chiroptical inversion could be realized in the presence of adiponitrile in certain solvents due to the solvation effects on the side ring and the threading of the vip into the pillar[5]arene cavity.However,the stronger self-included interactions between the cavity and the inside ring of certain MUJs led to inhibition of the switching.
基金support of this work by the National Natural Science Foundation of China (Nos. 21871194, 21572142, 21372165, 21402129 and 21402110)National Key Research and Development Program of China(No. 2017YFA0505903)+1 种基金Science & Technology Department of Sichuan Province(No. 2017SZ0021)Comprehensive Training Platform of Specialized Laboratory, College of Chemistry, Sichuan university
文摘Several cyclodextrin-cucurbit[6]uril-cowheeled [4]rotaxanes were synthesized through the cucurbit[6]uril-templated azide-alkyne 1,3-dipolar cycloaddition. The intramolecular interaction between the aromatic axle and the capping groups of cyclodextrin moieties was investigated by UV-vis, fluorescence,circular dichroism and NMR spectroscopic studies. The rotational kinetic of the wheel around the axle can be manipulated by adjusting the temperature. The capping group apparently slowed down the rotation of the wheel, playing a role of the brake, and lowering the temperature can stop the rotation of the wheel on the NMR timescale.
基金supported by the National Natural Science Foundation of China(22471182,22271201,92056116,22422108,22171194,22201194)the Fundamental Research Funds for the Central Universities(20826041D4117).
文摘While extensive research has explored manipulating supramolecular chirality through internal and external factors,the specific solvation effect remains uncharted territory.This study synthesized ortho-functionalized pillar[5]arene(P[5])derivatives Mn and Dn via thiol-Michael addition,characterizing them through spectroscopic and X-ray single-crystal analyses.Mn and Dn interacted with chiral amines,yielding significant circular dichroism(CD)responses.Intriguingly,the chiral induction exhibited pronounced specific solvation effects,where achiral alcohols either enhanced,attenuated,or reversed CD signals.Testing over 40 alcohols revealed correlations between the specific solvation effects and alcohol polarity and acidity.Molecular dynamics simulations unveiled that the alcohol interacted distinctly through hydrogen bonding,with one ion pair bonding up to four alcohol molecules.The Rp-and Sp-preference of the P[5]core could be altered by the number of bonded alcohols.This work uncovers the critical role of alcohol-specific solvation in ion pair-involved chiral assembly,pertinent for asymmetric ion-pairing catalysis and the use of alcohol additives in organic solvents.
文摘Nonlinearity in parallel compliance can be exploited to improve the performance of locomotion systems in terms of(1)energy efficiency,(2)control robustness,and(3)gait optimality;that is,attaining energy efficiency across a set of motions.Thus far,the literature has investigated and validated only the first two benefits.In this study,we present a new mathematical framework for designing nonlinear compliances in cyclic tasks encompassing all three benefits.We present an optimization-based formulation for each benefit to obtain the desired compliance profile.Furthermore,we analytically prove that,compared to linear compliance,using nonlinear compliance leads to(1)lower energy consumption,(2)better closed-loop performance,specifically in terms of tracking error,and(3)a higher diversity of natural frequencies.To compare the performance of linear and nonlinear compliance,we apply the proposed methods to a diverse set of robotic systems performing cyclic tasks,including a 2-DOF manipulator,a 3-DOF bipedal walker,and a hopper model.Compared to linear compliance,the nonlinear compliance leads to better performance in all aspects;for example,a 70%reduction in energy consumption and tracking error for the manipulator simulation.Regarding gait optimality,for all robotic simulation models,compared to linear compliance,the nonlinear compliance has lower energy consumption and tracking error over the considered set of motions.The proposed analytical studies and simulation results strongly support the idea that using nonlinear compliance significantly improves robotic system performance in terms of energy efficiency,control robustness,and gait optimality.
文摘Silver nanowires （AgNWs） surrounded by insulating poly（vinylpyrrolidone） have been synthesized by a polyol process and employed as transparent electrodes. The AgNW transparent electrodes can be fabricated by heattreatment at about 200 ℃ which forms connecting junctions between AgNWs. Such a heating process is, however, one of the drawbacks of the fabrication of AgNW electrodes on heat-sensitive substrates. Here it has been demonstrated that the electrical conductivity of AgNW electrodes can be improved by mechanical pressing at 25 MPa for 5 s at room temperature. This simple process results in a low sheet resistance of 8.6 Ω/square and a transparency of 80.0%, equivalent to the properties of the AgNW electrodes heated at 200 ℃. This technique makes it possible to fabricate AgNW transparent electrodes on heat-sensitive substrates. The AgNW electrodes on poly（ethylene terephthalate） films exhibited high stability of their electrical conductivities against the repeated bending test. In addition, the surface roughness of the pressed AgNW electrodes is one-third of that of the heat-treated electrode because the AgNW junctions are mechanically compressed. As a result, an organic solar cell fabricated on the pressed AgNW electrodes exhibited a power conversion as much as those fabricated on indium tin oxide electrodes. These findings enable continuous roll-to-roll processing at room temperature, resulting in relatively simple, inexpensive, and scalable processing that is suitable for forthcoming technologies such as organic solar cells, flexible displays, and touch screens.
基金the National Natural Science Foundation of China (Grant No. 50072017)
文摘Si3N4/BN nanocomposite powders with the mi-crostructure of the micro-sized a-Si3N4 particles coated with nano-sized BN particles were synthesized via the chemical reaction of boric acid, urea, and a-Si3N4 powder in a hydro-gen gas. The results of XRD, TEM, and selected area elec-tron diffraction showed that amorphous BN and a little amount of turbostratic BN(t-BN) were coated on Si3N4 parti-cles as the second phase after reaction at 1100℃. After re-heating the composite powders at 1450℃ in a nitrogen gas, the amorphous and turbostratic BN is transformed into h-BN. These nanocomposite powders can be used to prepare Si3N4/BN ceramic composites by hot-pressing at 1800℃, which have perfect machinability and can be drilled with normal metal tools.
文摘In this work, we have evaluated the biosensing capability of the porous silicon （PSi） based sidewall Bragg-grating resonator. The approximation of the quasi-TE mode full vector for the eigenmode calculation is performed using a full vector mode solver. The transmission spectra of the device are evaluated using the transfer matrix method. We have observed a shift in the resonant band for a change in the refractive index of biomaterial in the upper cladding region. The theoretical value of the bulk sensitivity is calculated to be 387.48nm/RIU. The device is suitable for biosensing application due to its ability of interacting signal with the infiltrated analytes in the PSi waveguide core.
基金supported by the National Natural Science Foundation of China(nos.21871194,21971169,and 21572142)National Key Research and Development Program of China(no.2017YFA0505903).
文摘Several novel macrocyclic arenes that are composed of six indole subunits,so-called bisindole[3]arenes(BID[3]s),were conveniently synthesized by the aluminum trichloride-catalyzed one-pot condensation of bisindole derivatives and paraformaldehyde in dichloromethane at room temperature.Their macrocyclic structures were demonstrated by X-ray single-crystal studies,and the presence of the macrocyclic cavities made it possible to accommodate specific small organic molecules.The BID[3]s have exceptionally high iodine adsorption ability due to the strong and synergic interaction of indole units toward iodine,exhibiting significant morphology changes upon adsorption and desorption of iodine.Iodine uptake capacity of up to 5.12 g·g^(−1) was found with MeBID[3],which is the highest value ever reported for macrocyclic arenes.
基金the New Funding Initiative 2010(NTU)the Academic Research Fund(AcRF)Tier1(RG 50/11),Ministry of Education,Singapore.
文摘Purpose–The purpose of this paper is to propose a method to avoid hyperstaticity and eventually reduce the magnitude of undesired force/torques.The authors also study the influence of hyperstaticity on human motor control during a redundant task.Design/methodology/approach–Increasing the level of transparency of robotic interfaces is critical to haptic investigations and applications.This issue is particularly important to robotic structures that mimic the human counterpart’s morphology and attach directly to the limb.Problems arise for complex joints such as the wrist,which cannot be accurately matched with a traditional mechanical joint.In such cases,mechanical differences between human and robotic joint cause hyperstaticity(i.e.over-constrained)which,coupled with kinematic misalignment,leads to uncontrolled force/torque at the joint.This paper focusses on the prono-supination(PS)degree of freedom of the forearm.The overall force and torque in the wrist PS rotation is quantified by means of a wrist robot.Findings–A practical solution to avoid hyperstaticity and reduce the level of undesired force/torque in the wrist is presented.This technique is shown to reduce 75 percent of the force and 68 percent of the torque.It is also shown an over-constrained mechanism could alter human motor strategies.Practical implications–The presented solution could be taken into account in the early phase of design of robots.It could also be applied to modify the fixation points of commercial robots in order to reduce the magnitude of reaction forces and avoid changes in motor strategy during the robotic therapy.Originality/value–In this paper for the first time the authors study the effect of hyperstaticity on both reaction forces and human motor strategies.
