Titanium monocarbide(TiC),which is the most stable titanium-based carbide,has attracted considerable interest in the fields of energy,catalysis,and structural materials due to its excellent properties.Synthesis of hig...Titanium monocarbide(TiC),which is the most stable titanium-based carbide,has attracted considerable interest in the fields of energy,catalysis,and structural materials due to its excellent properties.Synthesis of high-quality TiC powders with low cost and high efficiency is crucial for industrial applications;however major challenges face its realization.Herein,the methods for synthesizing TiC powders based on a reaction system are reviewed.This analysis is focused on the underlying mechanisms by which synthesis methods affect the quality of powders.Notably,strategies for improving the synthesis of highquality powders are analyzed from the perspective of enhancing heat and mass transfer processes.Furthermore,the critical issues,challenges,and development trends of the synthesis technology and application of high-quality TiC powder are discussed.展开更多
The component synthesis active vibration suppression method (CSVS) can be applied to suppress the vibration of flexible systems. By this method, several same or similar time-varying components are arranged according...The component synthesis active vibration suppression method (CSVS) can be applied to suppress the vibration of flexible systems. By this method, several same or similar time-varying components are arranged according to certain rules along the time axis. The synthesized command can suppress the arbitrary unwanted vibration harmonic while achieving the desired rigid body motion. The number of the components increases rapidly when the number of harmonic vibration is growing. In this article, the CSVS based on zero-placement technique is used to construct the synthesized command to suppress the multi-harmonics simultaneously in the discrete domain. The nature of zero-placement method is to put enough zeros to cancel system poles at necessary points. The designed synthesized command has equal time intervals between each component and which is much easier to be implemented. Using this method, the number of components increases linearly with the increasing of the number of being suppressed harmonics. For the spacecraft with flexible appendages, CSVS based on zero-placement is used to design the time optimal large angle maneuver control strategy. Simulations have verified the validity and superiority of the proposed approach.展开更多
Wastewater contamination by heavy metals and synthetic dyes presents a significant environmental challenge,necessitating effective and sustainable separation techniques.This review article provides a detailed examinat...Wastewater contamination by heavy metals and synthetic dyes presents a significant environmental challenge,necessitating effective and sustainable separation techniques.This review article provides a detailed examination of magnesium oxide(MgO)nanoparticles as an innovative nanoadsorbent for wastewater treatment,with a specific focus on heavy metal and dye removal.The review comprehensively explores various aspects of MgO nanoparticles,including their structural characteristics and synthesis techniques.The article delves into the morphology and crystallographic arrangement of MgO nanoparticles,offering insights into their structural attributes.Given the complexity of adsorption processes,the review identifies and analyzes parameters influencing the adsorption efficiency of MgO nanoparticles,such as temperature,pH,contact time,initial concentration,and co-existing ions.The interplay between these parameters and the adsorption capability of MgO nanoparticles emphasizes the importance of optimizing operational conditions.Furthermore,the review assesses various synthesis methods for MgO nanoparticles,including sol-gel,hydrothermal,precipitation,green synthesis,solvothermal,and template-assisted techniques.It discusses the advantages,limitations,and resulting nanoparticle characteristics of each method,enabling readers to grasp the implications of synthesis processes on adsorption efficiency.This comprehensive review consolidates current insights into the effectiveness of MgO nanoparticles as a potent nanoadsorbent for removing heavy metals and dyes from wastewater covering a wide spectrum of aspects related to MgO nanoparticles.Moreover,there is a need to investigate the use of MgO in the treatment of actual wastewater or river water,in order to leverage its cost-effectiveness and high efficiency for practical water treatment applications in real-time.展开更多
Efficiency of calculating a dynamic response is an important point of the compliant mechanism for posture adjustment.Dynamic modeling with low orders of a 2R1T compliant parallel mechanism is studied in the paper.The ...Efficiency of calculating a dynamic response is an important point of the compliant mechanism for posture adjustment.Dynamic modeling with low orders of a 2R1T compliant parallel mechanism is studied in the paper.The mechanism with two out-of-plane rotational and one lifting degrees of freedom(DoFs)plays an important role in posture adjustment.Based on elastic beam theory,the stiffness matrix and mass matrix of the beam element are established where the moment of inertia is considered.To improve solving efficiency,a dynamic model with low orders of the mechanism is established based on a modified modal synthesis method.Firstly,each branch of the RPR type mechanism is divided into a substructure.Subsequently,a set of hypothetical modes of each substructure is obtained based on the C-B method.Finally,dynamic equation of the whole mechanism is established by the substructure assembly.A dynamic experiment is conducted to verify the dynamic characteristics of the compliant mechanism.展开更多
Designing a sparse array with reduced transmit/receive modules(TRMs)is vital for some applications where the antenna system’s size,weight,allowed operating space,and cost are limited.Sparse arrays exhibit distinct ar...Designing a sparse array with reduced transmit/receive modules(TRMs)is vital for some applications where the antenna system’s size,weight,allowed operating space,and cost are limited.Sparse arrays exhibit distinct architectures,roughly classified into three categories:Thinned arrays,nonuniformly spaced arrays,and clustered arrays.While numerous advanced synthesis methods have been presented for the three types of sparse arrays in recent years,a comprehensive review of the latest development in sparse array synthesis is lacking.This work aims to fill this gap by thoroughly summarizing these techniques.The study includes synthesis examples to facilitate a comparative analysis of different techniques in terms of both accuracy and efficiency.Thus,this review is intended to assist researchers and engineers in related fields,offering a clear understanding of the development and distinctions among sparse array synthesis techniques.展开更多
LiMn2O4 spinel cathode materials were modified with 2 wt.%Li-M-PO4(M=Co,Ni,Mn) by polyol synthesis method.The phosphate surface-modified LiMn2O4 cathode materials were physically characterized by X-ray diffraction(...LiMn2O4 spinel cathode materials were modified with 2 wt.%Li-M-PO4(M=Co,Ni,Mn) by polyol synthesis method.The phosphate surface-modified LiMn2O4 cathode materials were physically characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM) and energy dispersive X-ray spectroscopy(EDS).The charge-discharge test showed that the cycling and rate capacities of LiMn2O4 cathode materials were significantly enhanced by stabilizing the electrode surface with phosphate.展开更多
Three kinds of processes, high temperature solid state reaction, precipitation and solgel technique were used to synthsize spinel phase LiMn2O4. XRD, DTATG results show that phasepure spinel LiMn2O4 could be synthesiz...Three kinds of processes, high temperature solid state reaction, precipitation and solgel technique were used to synthsize spinel phase LiMn2O4. XRD, DTATG results show that phasepure spinel LiMn2O4 could be synthesized under the lowest calcined temperature by the solgel technique compared to the precipitation method and solid state reaction. BET, SEM and electrochemical measurements results demonstrate that the features of the powders affect directly the electrochemical capacities; large specific area and small homogeneous grain size are of advantage for the lithium ion insertion and extraction in the charge and discharge process.展开更多
With the recent advancement in nanotechnology,nanoparticles(NPs)offer an ample variety of smart functions than conventional materials in various aspects.As compared to larger particles,NPs possess unique characteristi...With the recent advancement in nanotechnology,nanoparticles(NPs)offer an ample variety of smart functions than conventional materials in various aspects.As compared to larger particles,NPs possess unique characteristics and excellent abilities,such as low toxicity,chemical stability,surface functionality,and biocompatibility.These advantageous properties allow them to be widely utilized in many applications,including biomedical applications,energy applications,IT applications,and industrial applications.In order to fulfill the increasing demands of NP applications,existing NP synthesis methods need to be improved based on the requirements of different applications to further their usage.A comprehensive understanding of the relationships between synthesis parameters and properties of NPs can help us better fine-tune them with designed properties and minimal toxicity.This review paper will discuss the commonly used synthesis methods of functionalized NPs,as well as future directions and challenges to develop various synthesis methods further.展开更多
Colloidal semiconductor nanocrystals have been proven to be promising candidates for applications in low‐cost and high‐performance photovoltaics,bioimaging,and photocatalysis due to their novel size‐and shape‐depe...Colloidal semiconductor nanocrystals have been proven to be promising candidates for applications in low‐cost and high‐performance photovoltaics,bioimaging,and photocatalysis due to their novel size‐and shape‐dependent properties.Among the colloidal systems,I‐III‐VI semiconductor nanocrystals(NCs)have drawn much attention in the past few decades.Compared to binary NCs,ternary I‐III‐VI NCs not only exhibit low toxicity,but also a high performance similar to that of binary NCs.In this review,we mainly focus on the synthesis,properties,and applications of I‐III‐VI NCs.We summarize the major synthesis methods,analyze their photophysical and electronic properties,and highlight some of the latest applications of I‐III‐VI NCs in solar cells,light‐emitting diodes,bioimaging,and photocatalysis.Finally,based on the information reviewed,we highlight the existing problems and challenges.展开更多
Calcium looping method has been considered as one of the efficient options to capture C02 in the combustion Ilue gas. CaO-based sorbent is the basis for application of calcium looping and should be subjected to the se...Calcium looping method has been considered as one of the efficient options to capture C02 in the combustion Ilue gas. CaO-based sorbent is the basis for application of calcium looping and should be subjected to the severe calcination condition so as to obtain the concentrated C02 stream. In this research, CaO/CaZrO3 sorbents were synthesized using the sol-gel combustion synthesis (SGCS) method with urea as fuel. The cyclic reaction performance of the synthesized sorbents was evaluated on a lab-scaled reactor system through calcination at 950 ℃ in a pure C02 atmosphere and carbonation at 650 ℃ in the 15% (by volume) C02. The mass ratio of CaO to CaZr03 as 8:2 (designated as CasZr2) was screened as the best option among all the synthesized CaO sorbents for its high CO2 capture capacity and carbonation conversion at the initial cycle. And then a gradual decay in the C02 capture capacity was observed at the following 10 successive cycles, but hereafter stabilized throughout the later cycles. Furthermore, structural evolution of the carbonated CasZr2 over the looping cycles was investigated. With increasing looping cycles, the pore peak and mean grain size of the carbonated CasZr2 sorbent shifted to the bigger direction but both the surface area (SA) ratio and surface fractal dimension Ds decreased. Finally, morphological transformation of the carbonated CasZr2 was observed. Agglomeration and edge rounding of the newly formed CaC03 grains were found as aggravated at the cyclic carbonation stage. As a result, carbonation of CasZr2 with C02 was observed only confined to the external active CaO by the fast formation of the CaC03 shell outside, which occluded the further carbonation of the unreacted CaO inside. Therefore, enough attention should be paid to the carbonation stage and more effective activation measures should be explored to ensure the unreacted active CaO fully carbonatPd river the extended Ioonin cycles.展开更多
Polyaniline doped with heteropolyacid was synthesized using solid-state synthesis method. XRD pattern showed that polyaniline molecule has highly ordered arrangement. Fluorescence property of the polyaniline materia...Polyaniline doped with heteropolyacid was synthesized using solid-state synthesis method. XRD pattern showed that polyaniline molecule has highly ordered arrangement. Fluorescence property of the polyaniline materials was found.展开更多
The emerging two-dimensional MXene-derived quantum dots(MQDs)have garnered considerable research interest owing to their abundant active edge atoms,excellent electrical conductivity,and remarkable optical properties.C...The emerging two-dimensional MXene-derived quantum dots(MQDs)have garnered considerable research interest owing to their abundant active edge atoms,excellent electrical conductivity,and remarkable optical properties.Compared with their two-dimensional(2D)counterpart MXene,MQDs with forceful size and quantum confinement effects exhibit more unparalleled properties and have considerably contributed to the advanced photocatalysis,detection,energy storage,and biomedicine fields.This critical review summarizes the fundamental properties of MQDs in terms of structure,electricity,and optics.The mechanism,characteristics,and comparisons of two typical synthesis strategies(traditional chemical method and novel fluorine-free or chemical-free method)are also presented.Furthermore,the similarities and differences between MQDs and 2D MXenes are introduced in terms of their functional groups,light absorption capacity,energy band structure,and other properties.Moreover,recent advances in the applications of MQD-based materials for energy conversion and storage(ECS)are discussed,including photocatalysis,batteries,and supercapacitors.Finally,current challenges and future opportunities for advancing MQD-based materials in the promising ECS field are presented.展开更多
A convenient method for synthesis of tetragonal FeS using iron powder as iron source, is reported. Nanocrystalline tetragonal FeS samples were successfully synthesized by reacting metallic iron powder with sodium sulf...A convenient method for synthesis of tetragonal FeS using iron powder as iron source, is reported. Nanocrystalline tetragonal FeS samples were successfully synthesized by reacting metallic iron powder with sodium sulfide in acetate buffer solution. The obtained sample is single-phase tetragonal FeS with lattice parameters a = 0.3767 nm and c = 0.5037 nm, as revealed by X-ray diffraction. The sample consists of fiat nanosheets with lateral dimensions from 20 nm up to 200 nm and average thickness of about 20 nm. We found that tetragonal FeS is a fairly good conductor from the electrical resistivity measurement on a pellet of the nanosheets. The temperature dependence of conductivity of the pellet was well fitted using an empirical equation wherein the effect of different grain boundaries was taken into consideration. This study provides a convenient, economic way to synthesize tetragonal FeS in a large scale and reports the first electrical conductivity data for tetragonal FeS down to liquid helium temperature.展开更多
A method for the conversion of α-acetamido-β-substituted phenyl acrylic acid (αtβSPAA)into substituted phenyl lactic acid(SPLA)is described and an improved Clemmensen reduction reagent is used.
xLi2MnO3·(1-x)Li(Ni1/3Co1/3Mn1/3)O2 (x=0.25, 0.40, 0.55) compounds were prepared by low-heating solid state reaction. In the voltage range of 2.70-4.35 V, the discharge capacity of the electrode decreased w...xLi2MnO3·(1-x)Li(Ni1/3Co1/3Mn1/3)O2 (x=0.25, 0.40, 0.55) compounds were prepared by low-heating solid state reaction. In the voltage range of 2.70-4.35 V, the discharge capacity of the electrode decreased with the increase of x, with a better cyclability. However, when cycled between 2.7 and 4.6 V, the cathodes delivered much larger capacities and their capacities increased with the introduction of Li2MnO3. Moreover, it was found that the discharge capacity gradually increased with the cycle number. The reason for this phenomenon was discussed. It was found that the relatively low cut-off potential made the activation of the Li2MnO3 component in the compound a gradual process, which caused the increasing capacity.展开更多
PEDOT nanotubes were prepared by a template synthesis method. Based on our template, it was deduced that there are two successive processes in the formation of nanotubes. The first step is soakage of the porous templa...PEDOT nanotubes were prepared by a template synthesis method. Based on our template, it was deduced that there are two successive processes in the formation of nanotubes. The first step is soakage of the porous templates by a polymer solution, and the second step is adsorption of free charged cationic groups and doped PEDOT onto the template surface with negative charges. XRD results showed that well orientated PEDOT chains were formed during the synthesis, moreover the arrange conductivity of molecular chains strongly affect the structures of PEDOT nanotubes. The nanotubes were measured to be about 5.5-17.6 S/cm, which is higher than that of nanotube pellet due to the high contact resistance between the adjacent nanotubes.展开更多
The title compound was synthesized by a one pot synthesis method with ethanolamine ,ketone and dichloroacetyl chloride. The product was characterization by IR, 1 HNMR,UV, and elementary analysis.
The subsystem synthesis method has been developed in order to improve computational efficiency for a multibody vehicle dynamics model. Using the subsystem synthesis method, equations of motion of the base body and eac...The subsystem synthesis method has been developed in order to improve computational efficiency for a multibody vehicle dynamics model. Using the subsystem synthesis method, equations of motion of the base body and each subsystem can be solved separately. In the subsystem synthesis method, various coordinate systems can be used and various integration methods can be applied in each subsystem, as long as the effective mass matrix and the effective force vector are properly produced. In this paper, comparative study has been carried out for the subsystem synthesis method with Cartesian coordinates and with joint relative coordinates. Two different integration methods such as an explicit integrator and an explicit implicit integrator are employed. In order to see the accuracy and computational efficiency from the different models based on the different coordinate systems and different integration methods, a rough terrain run simulations has been carried out with a 6 × 6 off-road multibody vehicle model.展开更多
Systematic effort dedicated to the exploration of feasible ways how to permanently come up with even more space-efficient implementation of digital circuits based on conventional CMOS technology node may soon reach th...Systematic effort dedicated to the exploration of feasible ways how to permanently come up with even more space-efficient implementation of digital circuits based on conventional CMOS technology node may soon reach the ultimate point, which is mostly given by the constraints associated with physical scaling of fundamental electronic components. One of the possible ways of how to mitigate this problem can be recognized in deployment of multifunctional circuit elements. In addition, the polymorphic electronics paradigm, with its considerable independence on a parti- cular technology, opens a way how to fulfil this objective through the adoption of emerging semiconductor materials and advanced synthesis methods. In this paper, main attention is focused on the introduction of polymorphic operators (i.e. digital logic gates) that would allow to further increase the efficiency of multifunctional circuit synthesis techniques. Key aspect depicting the novelty of the proposed approach is primarily based on the intrinsic exploitation of components with ambi- polar conduction property. Finally, relevant models of the polymorphic operators are presented in conjunction with the experimental results.展开更多
o-Carboxybenzaldehyde (1)and acetone gave the Claisen-Schmidt condensation product, which readily cyclizes on acidification to give 1-oxo-3-acetonyl-dihydrobenzo [c]furan(4)in 68% yield. Other methyl ketones behaved s...o-Carboxybenzaldehyde (1)and acetone gave the Claisen-Schmidt condensation product, which readily cyclizes on acidification to give 1-oxo-3-acetonyl-dihydrobenzo [c]furan(4)in 68% yield. Other methyl ketones behaved similarly.展开更多
基金supported by Basic Frontier Scientific Research of the Chinese Academy of Sciences(ZDBS-LY-JSC041)the National Natural Science Foundation of China(22178348)+1 种基金the open research fund of the State Key Laboratory of Mesoscience and Engineering(MESO-23-D06)the Youth Innovation Promotion Association CAS(292021000085)。
文摘Titanium monocarbide(TiC),which is the most stable titanium-based carbide,has attracted considerable interest in the fields of energy,catalysis,and structural materials due to its excellent properties.Synthesis of high-quality TiC powders with low cost and high efficiency is crucial for industrial applications;however major challenges face its realization.Herein,the methods for synthesizing TiC powders based on a reaction system are reviewed.This analysis is focused on the underlying mechanisms by which synthesis methods affect the quality of powders.Notably,strategies for improving the synthesis of highquality powders are analyzed from the perspective of enhancing heat and mass transfer processes.Furthermore,the critical issues,challenges,and development trends of the synthesis technology and application of high-quality TiC powder are discussed.
文摘The component synthesis active vibration suppression method (CSVS) can be applied to suppress the vibration of flexible systems. By this method, several same or similar time-varying components are arranged according to certain rules along the time axis. The synthesized command can suppress the arbitrary unwanted vibration harmonic while achieving the desired rigid body motion. The number of the components increases rapidly when the number of harmonic vibration is growing. In this article, the CSVS based on zero-placement technique is used to construct the synthesized command to suppress the multi-harmonics simultaneously in the discrete domain. The nature of zero-placement method is to put enough zeros to cancel system poles at necessary points. The designed synthesized command has equal time intervals between each component and which is much easier to be implemented. Using this method, the number of components increases linearly with the increasing of the number of being suppressed harmonics. For the spacecraft with flexible appendages, CSVS based on zero-placement is used to design the time optimal large angle maneuver control strategy. Simulations have verified the validity and superiority of the proposed approach.
基金the support of the Khalifa University internal funding CIRA-2021-071(8474000416),Khalifa University,UAEthe financial support from the Science batch of 1976-1980 of the University of Peradeniya,Sri Lanka。
文摘Wastewater contamination by heavy metals and synthetic dyes presents a significant environmental challenge,necessitating effective and sustainable separation techniques.This review article provides a detailed examination of magnesium oxide(MgO)nanoparticles as an innovative nanoadsorbent for wastewater treatment,with a specific focus on heavy metal and dye removal.The review comprehensively explores various aspects of MgO nanoparticles,including their structural characteristics and synthesis techniques.The article delves into the morphology and crystallographic arrangement of MgO nanoparticles,offering insights into their structural attributes.Given the complexity of adsorption processes,the review identifies and analyzes parameters influencing the adsorption efficiency of MgO nanoparticles,such as temperature,pH,contact time,initial concentration,and co-existing ions.The interplay between these parameters and the adsorption capability of MgO nanoparticles emphasizes the importance of optimizing operational conditions.Furthermore,the review assesses various synthesis methods for MgO nanoparticles,including sol-gel,hydrothermal,precipitation,green synthesis,solvothermal,and template-assisted techniques.It discusses the advantages,limitations,and resulting nanoparticle characteristics of each method,enabling readers to grasp the implications of synthesis processes on adsorption efficiency.This comprehensive review consolidates current insights into the effectiveness of MgO nanoparticles as a potent nanoadsorbent for removing heavy metals and dyes from wastewater covering a wide spectrum of aspects related to MgO nanoparticles.Moreover,there is a need to investigate the use of MgO in the treatment of actual wastewater or river water,in order to leverage its cost-effectiveness and high efficiency for practical water treatment applications in real-time.
基金Supported by National Natural Science Foundation of China (Grant No.51975007)。
文摘Efficiency of calculating a dynamic response is an important point of the compliant mechanism for posture adjustment.Dynamic modeling with low orders of a 2R1T compliant parallel mechanism is studied in the paper.The mechanism with two out-of-plane rotational and one lifting degrees of freedom(DoFs)plays an important role in posture adjustment.Based on elastic beam theory,the stiffness matrix and mass matrix of the beam element are established where the moment of inertia is considered.To improve solving efficiency,a dynamic model with low orders of the mechanism is established based on a modified modal synthesis method.Firstly,each branch of the RPR type mechanism is divided into a substructure.Subsequently,a set of hypothetical modes of each substructure is obtained based on the C-B method.Finally,dynamic equation of the whole mechanism is established by the substructure assembly.A dynamic experiment is conducted to verify the dynamic characteristics of the compliant mechanism.
基金supported by the National Natural Science Foundation of China under Grant No.U2341208.
文摘Designing a sparse array with reduced transmit/receive modules(TRMs)is vital for some applications where the antenna system’s size,weight,allowed operating space,and cost are limited.Sparse arrays exhibit distinct architectures,roughly classified into three categories:Thinned arrays,nonuniformly spaced arrays,and clustered arrays.While numerous advanced synthesis methods have been presented for the three types of sparse arrays in recent years,a comprehensive review of the latest development in sparse array synthesis is lacking.This work aims to fill this gap by thoroughly summarizing these techniques.The study includes synthesis examples to facilitate a comparative analysis of different techniques in terms of both accuracy and efficiency.Thus,this review is intended to assist researchers and engineers in related fields,offering a clear understanding of the development and distinctions among sparse array synthesis techniques.
基金financially supported by the National High-Tech Research and Development(863) Program of China(No.2006AA11A160)the National Natural Science Foundation of China(No.50604018)
文摘LiMn2O4 spinel cathode materials were modified with 2 wt.%Li-M-PO4(M=Co,Ni,Mn) by polyol synthesis method.The phosphate surface-modified LiMn2O4 cathode materials were physically characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM) and energy dispersive X-ray spectroscopy(EDS).The charge-discharge test showed that the cycling and rate capacities of LiMn2O4 cathode materials were significantly enhanced by stabilizing the electrode surface with phosphate.
文摘Three kinds of processes, high temperature solid state reaction, precipitation and solgel technique were used to synthsize spinel phase LiMn2O4. XRD, DTATG results show that phasepure spinel LiMn2O4 could be synthesized under the lowest calcined temperature by the solgel technique compared to the precipitation method and solid state reaction. BET, SEM and electrochemical measurements results demonstrate that the features of the powders affect directly the electrochemical capacities; large specific area and small homogeneous grain size are of advantage for the lithium ion insertion and extraction in the charge and discharge process.
文摘With the recent advancement in nanotechnology,nanoparticles(NPs)offer an ample variety of smart functions than conventional materials in various aspects.As compared to larger particles,NPs possess unique characteristics and excellent abilities,such as low toxicity,chemical stability,surface functionality,and biocompatibility.These advantageous properties allow them to be widely utilized in many applications,including biomedical applications,energy applications,IT applications,and industrial applications.In order to fulfill the increasing demands of NP applications,existing NP synthesis methods need to be improved based on the requirements of different applications to further their usage.A comprehensive understanding of the relationships between synthesis parameters and properties of NPs can help us better fine-tune them with designed properties and minimal toxicity.This review paper will discuss the commonly used synthesis methods of functionalized NPs,as well as future directions and challenges to develop various synthesis methods further.
文摘Colloidal semiconductor nanocrystals have been proven to be promising candidates for applications in low‐cost and high‐performance photovoltaics,bioimaging,and photocatalysis due to their novel size‐and shape‐dependent properties.Among the colloidal systems,I‐III‐VI semiconductor nanocrystals(NCs)have drawn much attention in the past few decades.Compared to binary NCs,ternary I‐III‐VI NCs not only exhibit low toxicity,but also a high performance similar to that of binary NCs.In this review,we mainly focus on the synthesis,properties,and applications of I‐III‐VI NCs.We summarize the major synthesis methods,analyze their photophysical and electronic properties,and highlight some of the latest applications of I‐III‐VI NCs in solar cells,light‐emitting diodes,bioimaging,and photocatalysis.Finally,based on the information reviewed,we highlight the existing problems and challenges.
基金Supported by the National Natural Science Foundation of China(51276210,50906030,31301586)the Partial Financial Grant of North China University of Water Resources and Electric Power(201012)the National Basic Research Program of China(2011CB707301)
文摘Calcium looping method has been considered as one of the efficient options to capture C02 in the combustion Ilue gas. CaO-based sorbent is the basis for application of calcium looping and should be subjected to the severe calcination condition so as to obtain the concentrated C02 stream. In this research, CaO/CaZrO3 sorbents were synthesized using the sol-gel combustion synthesis (SGCS) method with urea as fuel. The cyclic reaction performance of the synthesized sorbents was evaluated on a lab-scaled reactor system through calcination at 950 ℃ in a pure C02 atmosphere and carbonation at 650 ℃ in the 15% (by volume) C02. The mass ratio of CaO to CaZr03 as 8:2 (designated as CasZr2) was screened as the best option among all the synthesized CaO sorbents for its high CO2 capture capacity and carbonation conversion at the initial cycle. And then a gradual decay in the C02 capture capacity was observed at the following 10 successive cycles, but hereafter stabilized throughout the later cycles. Furthermore, structural evolution of the carbonated CasZr2 over the looping cycles was investigated. With increasing looping cycles, the pore peak and mean grain size of the carbonated CasZr2 sorbent shifted to the bigger direction but both the surface area (SA) ratio and surface fractal dimension Ds decreased. Finally, morphological transformation of the carbonated CasZr2 was observed. Agglomeration and edge rounding of the newly formed CaC03 grains were found as aggravated at the cyclic carbonation stage. As a result, carbonation of CasZr2 with C02 was observed only confined to the external active CaO by the fast formation of the CaC03 shell outside, which occluded the further carbonation of the unreacted CaO inside. Therefore, enough attention should be paid to the carbonation stage and more effective activation measures should be explored to ensure the unreacted active CaO fully carbonatPd river the extended Ioonin cycles.
文摘Polyaniline doped with heteropolyacid was synthesized using solid-state synthesis method. XRD pattern showed that polyaniline molecule has highly ordered arrangement. Fluorescence property of the polyaniline materials was found.
文摘The emerging two-dimensional MXene-derived quantum dots(MQDs)have garnered considerable research interest owing to their abundant active edge atoms,excellent electrical conductivity,and remarkable optical properties.Compared with their two-dimensional(2D)counterpart MXene,MQDs with forceful size and quantum confinement effects exhibit more unparalleled properties and have considerably contributed to the advanced photocatalysis,detection,energy storage,and biomedicine fields.This critical review summarizes the fundamental properties of MQDs in terms of structure,electricity,and optics.The mechanism,characteristics,and comparisons of two typical synthesis strategies(traditional chemical method and novel fluorine-free or chemical-free method)are also presented.Furthermore,the similarities and differences between MQDs and 2D MXenes are introduced in terms of their functional groups,light absorption capacity,energy band structure,and other properties.Moreover,recent advances in the applications of MQD-based materials for energy conversion and storage(ECS)are discussed,including photocatalysis,batteries,and supercapacitors.Finally,current challenges and future opportunities for advancing MQD-based materials in the promising ECS field are presented.
基金Project supported by the National Natural Science Foundation of China(Grant No.21271183)the National Basic Research Program of China(Grant Nos.2011CBA00112 and 2011CB808202)
文摘A convenient method for synthesis of tetragonal FeS using iron powder as iron source, is reported. Nanocrystalline tetragonal FeS samples were successfully synthesized by reacting metallic iron powder with sodium sulfide in acetate buffer solution. The obtained sample is single-phase tetragonal FeS with lattice parameters a = 0.3767 nm and c = 0.5037 nm, as revealed by X-ray diffraction. The sample consists of fiat nanosheets with lateral dimensions from 20 nm up to 200 nm and average thickness of about 20 nm. We found that tetragonal FeS is a fairly good conductor from the electrical resistivity measurement on a pellet of the nanosheets. The temperature dependence of conductivity of the pellet was well fitted using an empirical equation wherein the effect of different grain boundaries was taken into consideration. This study provides a convenient, economic way to synthesize tetragonal FeS in a large scale and reports the first electrical conductivity data for tetragonal FeS down to liquid helium temperature.
文摘A method for the conversion of α-acetamido-β-substituted phenyl acrylic acid (αtβSPAA)into substituted phenyl lactic acid(SPLA)is described and an improved Clemmensen reduction reagent is used.
基金supported by the National Natural Science Foundation of China(No.50472093,50702007)
文摘xLi2MnO3·(1-x)Li(Ni1/3Co1/3Mn1/3)O2 (x=0.25, 0.40, 0.55) compounds were prepared by low-heating solid state reaction. In the voltage range of 2.70-4.35 V, the discharge capacity of the electrode decreased with the increase of x, with a better cyclability. However, when cycled between 2.7 and 4.6 V, the cathodes delivered much larger capacities and their capacities increased with the introduction of Li2MnO3. Moreover, it was found that the discharge capacity gradually increased with the cycle number. The reason for this phenomenon was discussed. It was found that the relatively low cut-off potential made the activation of the Li2MnO3 component in the compound a gradual process, which caused the increasing capacity.
基金Funded National Natural Science Foundation of China(No.: 60372002)
文摘PEDOT nanotubes were prepared by a template synthesis method. Based on our template, it was deduced that there are two successive processes in the formation of nanotubes. The first step is soakage of the porous templates by a polymer solution, and the second step is adsorption of free charged cationic groups and doped PEDOT onto the template surface with negative charges. XRD results showed that well orientated PEDOT chains were formed during the synthesis, moreover the arrange conductivity of molecular chains strongly affect the structures of PEDOT nanotubes. The nanotubes were measured to be about 5.5-17.6 S/cm, which is higher than that of nanotube pellet due to the high contact resistance between the adjacent nanotubes.
文摘The title compound was synthesized by a one pot synthesis method with ethanolamine ,ketone and dichloroacetyl chloride. The product was characterization by IR, 1 HNMR,UV, and elementary analysis.
基金supported from by Unmanned Technology Research Center (UTRC) at Korea Advanced Institute of Science and Technology (KAIST),originally funded by DAPA,ADD
文摘The subsystem synthesis method has been developed in order to improve computational efficiency for a multibody vehicle dynamics model. Using the subsystem synthesis method, equations of motion of the base body and each subsystem can be solved separately. In the subsystem synthesis method, various coordinate systems can be used and various integration methods can be applied in each subsystem, as long as the effective mass matrix and the effective force vector are properly produced. In this paper, comparative study has been carried out for the subsystem synthesis method with Cartesian coordinates and with joint relative coordinates. Two different integration methods such as an explicit integrator and an explicit implicit integrator are employed. In order to see the accuracy and computational efficiency from the different models based on the different coordinate systems and different integration methods, a rough terrain run simulations has been carried out with a 6 × 6 off-road multibody vehicle model.
文摘Systematic effort dedicated to the exploration of feasible ways how to permanently come up with even more space-efficient implementation of digital circuits based on conventional CMOS technology node may soon reach the ultimate point, which is mostly given by the constraints associated with physical scaling of fundamental electronic components. One of the possible ways of how to mitigate this problem can be recognized in deployment of multifunctional circuit elements. In addition, the polymorphic electronics paradigm, with its considerable independence on a parti- cular technology, opens a way how to fulfil this objective through the adoption of emerging semiconductor materials and advanced synthesis methods. In this paper, main attention is focused on the introduction of polymorphic operators (i.e. digital logic gates) that would allow to further increase the efficiency of multifunctional circuit synthesis techniques. Key aspect depicting the novelty of the proposed approach is primarily based on the intrinsic exploitation of components with ambi- polar conduction property. Finally, relevant models of the polymorphic operators are presented in conjunction with the experimental results.
文摘o-Carboxybenzaldehyde (1)and acetone gave the Claisen-Schmidt condensation product, which readily cyclizes on acidification to give 1-oxo-3-acetonyl-dihydrobenzo [c]furan(4)in 68% yield. Other methyl ketones behaved similarly.