Triplexers are designed based on SOl flattop arrayed waveguide gratings （AWGs）. Three wavelengths （1310, 1490,and 1550nm） operate at three diffraction orders of AWGs. Simulation shows that the 3dB bandwidth,crosst...Triplexers are designed based on SOl flattop arrayed waveguide gratings （AWGs）. Three wavelengths （1310, 1490,and 1550nm） operate at three diffraction orders of AWGs. Simulation shows that the 3dB bandwidth,crosstalk, and loss are 6nm,less than -40dB, and 5dB, respectively. The output optical fields of the device fabricated in our laboratory are clear and show a good triplexing function.展开更多
We investigate an optical compact triplexer based on two photonic crystal waveguides and resonant cavities. For performing wavelength selection, we use three core-shell rods as the resonant cavities. The core rods are...We investigate an optical compact triplexer based on two photonic crystal waveguides and resonant cavities. For performing wavelength selection, we use three core-shell rods as the resonant cavities. The core rods are created by introducing air holes in the center of the silicon rods. By varying the radii of the air holes, three specific wavelengths 1.31, 1.49 and 1.55μm can be obtained. This structure is designed and its performance is verified by the finite-difference time-domain method, which is highly suitable for photonic integrated circuits （PICs）. The average output transmission efficiency and quality factor are more than 98.85% and 560, respectively. The mean value of the crosstalk between output channels is about -36.49 dB. The present device is extremely compact with total size 96.24μm2, which is suitable for PICs and can be utilized in the fiber-to-the-home system.展开更多
In this work, we propose a new design of all-optical triplexer based on of metal–insulator–metal（MIM） plasmonic waveguide structures and ring resonators. By adjusting the radii of ring resonators and the gap dista...In this work, we propose a new design of all-optical triplexer based on of metal–insulator–metal（MIM） plasmonic waveguide structures and ring resonators. By adjusting the radii of ring resonators and the gap distance, certain wavelengths can be filtered out and the crosstalk of each channel can also be reduced. The numerical results show that the proposed MIM plasmonic waveguide structure can really function as an optical triplexer with respect to the three wavelengths, that is, 1310, 1490, and 1550 nm, respectively. It can be widely used as the fiber access network element for multiplexer–demultiplexer wavelength selective in fiber-to-the-home communication systems with transmission efficiency higher than 90%. It can also be a potential key component in the applications of the biosensing systems.展开更多
Strand displacement reaction is a crucial component in the assembly of diverse DNA-based nanodevices,with the toehold-mediated strand displacement reaction representing the prevailing strategy.However,the single-stran...Strand displacement reaction is a crucial component in the assembly of diverse DNA-based nanodevices,with the toehold-mediated strand displacement reaction representing the prevailing strategy.However,the single-stranded Watson-Crick sticky region that serves as the trigger for strand displacement can also cause leakage reactions by introducing crosstalk in complex DNA circuits.Here,we proposed the toeless and reversible DNA strand displacement reaction based on the Hoogsteen-bond triplex,which is compatible with most of the existing DNA circuits.We demonstrated that our proposed reaction can occur at pH 5 and can be reversed at pH 9.We also observed an approximately linear relationship between the degree of reaction and pH within the range of pH 5-6,providing the potential for precise regulation of the reaction.Meanwhile,by altering the sequence orientation,we have demonstrated that our proposed reaction can be initiated or regulated through the same toeless mechanism without the requirement for protonation in low pH conditions.Based on the proposed reaction principle,we further constructed a variety of DNA nanodevices,including two types of DNA logic gates that rely on pH 5/pH 9 changes for initiating and reversing:the AND gate and the OR gate.We also successfully constructed a DNA Walker based on our proposed reaction modes,which can move along a given track after the introduction of a programmable DNA sequence and complete a cycle after 4 steps.Our findings suggest that this innovative approach will have broad utility in the development of DNA circuits,molecular sensors,and other complex biological systems.展开更多
The clustered regularly interspersed short palindromic repeats/CRISPR-associated protein 9(CRISPR/Cas9)system is an RNA-guided platform for highly efficient and specific genome targeting in diverse organisms,which has...The clustered regularly interspersed short palindromic repeats/CRISPR-associated protein 9(CRISPR/Cas9)system is an RNA-guided platform for highly efficient and specific genome targeting in diverse organisms,which has been exploited for various applications in gene manipulation.Compared with the constantly active CRISPR/Cas9 function,conditional control of its activity can improve the performance of the system with reduced side effects and high spatiotemporal precision.The pH-responsive triplex RNA was successful used in CRISPR-derived RNA/trans-activating crRNA(crRNA/tracrRNA)of CRISPR/Cas9,thus affecting RNA/dead Cas9(dCas9)complex to target DNA in vitro and in vivo.This design of triplex RNA opens a new window towards the broad involvement of eukaryotic cells for conditional control of CRISPR/Cas9function.?2024 Published by Elsevier B.V.on behalf of Chinese Chemical Society and Institute of Materia Medica,Chinese Academy of Medical Sciences.展开更多
DNA circuits are powerful tools in various applications such as logical computation,molecular diagnosis and synthetic biology.Leakage is a major problem in constructing complex DNA circuits.It directly affects the out...DNA circuits are powerful tools in various applications such as logical computation,molecular diagnosis and synthetic biology.Leakage is a major problem in constructing complex DNA circuits.It directly affects the output signal and harms the circuit’s performance significantly.In the traditional DNA circuits,the gate complex is a duplex structure.There are insufficient energy barriers to prevent spontaneous detachment of strands,resulting in a leak prone.Herein,we have developed triplex-structure based DNA circuit with ultra-low leakage and high signal-to-noise ratio(SNR).The triplex structure improves the stability in the absence of input.At the same time,the driving force of the strand displacement cascades reduces the influence of the triplex structure on the desired reaction.The SNR of the DNA circuit was increased to 695,while the desired reaction rate remained 90%of the conventional translator circuit.The triplex-structure mediated leakage prevention strategy was further tested at different temperatures and in DNA translator and seesaw circuits.We also constructed modular basic logic gates with a high efficiency and low leakage.On this basis,we further constructed triplex-structure based tertiary DNA logic circuits,and the SNR reached 295,which,to the best of our knowledge,was among the highest of the field.We believe that our scheme provides a novel,valid,and general tool for reducing leakages,and we anticipate that it will be widely adopted in DNA nanotechnology.展开更多
A novel Si-Al alloyed press hardening steel(PHS)with the ferrite(α)-austenite(γ)-martensite(α')triplex microstructure was developed to have marginal oxidization after the hot forming in air,and the resultant ul...A novel Si-Al alloyed press hardening steel(PHS)with the ferrite(α)-austenite(γ)-martensite(α')triplex microstructure was developed to have marginal oxidization after the hot forming in air,and the resultant ultimate tensile strength(UTS)of 1620 MPa and total elongation(TE)of 14%were achieved simultaneously at reduced density.Both performances are superior to the existing PHSs.Particularly,the baking at 170°C leads to remarkable increases in both strength and ductility together with the transition of tensile fracture from the brittle interfacial cracking to the ductile one.This is because austenite and ferrite were hardened due to the segregation of C atoms into geometry necessary dislocations(GNDs)but martensite softened due to the loss of supersaturated C atoms during the baking.Atomic probe tomography examination reveals that some C atoms segregated to theα/α'interfaces during the baking for increased cohesive energy of the phase interface,thus hindering the interfacial cracking.In addition,the employed Al/Si alloying affords stronger oxidization resistance than both Al/Cr and Si/Cr because they are more rapidly oxidized than Cr to form the dense Al_(2) O_(3)/SiO_(2) layers for earlier protection.展开更多
In this paper, we report the influence of cooling processes on the yielding behavior of a medium Mn steel(MMS) with triplex microstructure, i.e. austenite(γ), ferrite(α) and as-quenched martensite(α’). After the i...In this paper, we report the influence of cooling processes on the yielding behavior of a medium Mn steel(MMS) with triplex microstructure, i.e. austenite(γ), ferrite(α) and as-quenched martensite(α’). After the intercritical annealing(IA) at both 725℃ and 750℃, the steel was subjected to the two cooling processes, i.e. air cooling(AC) and water quenching(WQ). It exhibits the discontinuous yielding after the AC following the IA at 750℃ while the continuous yielding after the WQ. Compared with WQ process,both the dilatometry and the microstructural examinations show that the AC process leads to lower Ms temperature, larger retained austenite(RA) fraction and less martensite, the latter is always companied with geometry necessary dislocations(GNDs) generated near the α/α’ interfaces. Considering the complexity of nanosized tri-phases in this steel, the presence of martensite with key features in the resultant specimens was systematically examined by atom probe tomography(APT) on the samples prepared by the specific target lift-out method. The APT results directly revealed the C/Mn co-segregation at the α’/αinterfaces in the AC samples but not in WQ samples. The numerical simulation results further suggest that the segregation of C and Mn at the α’/α interfaces may be due to different mechanisms. We conclude that the yielding of triplex MMS is determined by both the quantity of GNDs generated near theα/α’ interfaces, which increases with martensite fraction, and the extent of their immobilization resulting from the interfacial segregation of solute atoms when the presence of martensite is sufficient. WQ tends to suppress the discontinuous yielding of MMS since the rapid cooling may promote more martensite formed with the increasing quantity of GNDs and prevent the interfacial segregation of both C and Mn.展开更多
Phase-field modelling of microstructural evolution in polycrystalline systems with phase-associated grains has largely been confined to continuum-field models.In this study,a multiphase-field approach,with a provision...Phase-field modelling of microstructural evolution in polycrystalline systems with phase-associated grains has largely been confined to continuum-field models.In this study,a multiphase-field approach,with a provision for introducing grain boundary and interphase diffusion,is extended to analyse concurrent grain growth and coarsening in multicomponent polycrystalline microstructures with chemically-distinct grains.The effect of the number of phases and components on the kinetics of evolution is investigated by considering binary and ternary systems of duplex and triplex microstructures,along with a single phase system.It is realised that the mere increase in the number of phases minimises the rate of concurrent grain growth and coarsening.However,the effect of components is substantially dependent on the respective kinetic coefficients.This work unravels that the disparity in the influence of phases and components is primarily due to the corresponding change introduced in the transformation mechanism.While the raise in number of phases convolutes the diffusion paths,the increase in number of component effects the rate of evolution through the interdiffusion,which introduces interdependency in the diffusing chemical-species.Additionally,the role of phase-fractions on the transformation rate of triplex microstructure is studied,and correspondingly,the interplay of interface-and diffusion-governed evolution is elucidated.A representative evolution of three-dimensional triplex microstructure with equal phase-fraction is comparatively analysed with the evolution of corresponding two-dimensional setup.展开更多
Saxitoxin(STX),one of the most toxic paralytic shellfish poisons discovered to date,is listed as a required item of aquatic product safety inspection worldwide.However,conventional detection methods for STX are limite...Saxitoxin(STX),one of the most toxic paralytic shellfish poisons discovered to date,is listed as a required item of aquatic product safety inspection worldwide.However,conventional detection methods for STX are limited by various issues,such as low sensitivity,complicated operations,and ethical considerations.In this study,an aptamer-triplex molecular switch(APT-TMS)and gold nanoparticle(AuNP)nanozyme were combined to develop a label-free colorimetric aptasensor for the rapid and highly sensitive de-tection of STX.An anti-STX aptamer designed with pyrimidine arms and a purine chain was fabricated to form an APT-TMS.Specific binding between the aptamer and STX triggered the opening of the switch,which causes the purine chains to adsorb onto the surface of the AuNPs and enhances the peroxidase-like activity of the AuNP nanozyme toward 3,3’,5,5’-tetramethylbenzidine.Under optimized conditions,the proposed aptasensor showed high sensitivity and selectivity for STX,with a limit of detection of 335.6 pmol L^(−1) and a linear range of 0.59-150 nmol L^(−1).Moreover,good recoveries of 82.70%-92.66%for shellfish and 88.97%-106.5%for seawater were obtained.The analysis could be completed within 1 h.The proposed design also offers a robust strategy to achieve detection of other marine toxin targets by altering the corresponding aptamers.展开更多
CRISPR/Cas9(clustered regularly interspaced short palindromic repeats(CRISPR)/CRISPR-associated protein 9)系统具有高效、简单、易编辑等特性,在基因工程方面具有巨大潜能。在果蝇(Drosophila melanogaster)基因功能研究中,CRIS...CRISPR/Cas9(clustered regularly interspaced short palindromic repeats(CRISPR)/CRISPR-associated protein 9)系统具有高效、简单、易编辑等特性,在基因工程方面具有巨大潜能。在果蝇(Drosophila melanogaster)基因功能研究中,CRISPR/Cas9系统也得到了广泛应用。然而利用传统的CRISPR/Cas9系统编辑果蝇基因时,Cas9与sgRNA表达元件往往分别存在于不同果蝇中,需要通过复杂的遗传杂交过程将Cas9与sgRNA整合到一个个体中,操作周期长且较为复杂。本研究在CRISPR/Cas9系统基础上引入tRNA-sgRNA系统和triplex元件,利用triplex元件连接Cas9和tRNA-sgRNA基因,稳定单转录本切割后Cas9 mRNA的末端,实现一个转录本可以同时表达Cas9蛋白和sgRNA,通过一次杂交即可得到相应表型的后代,简化了遗传操作过程。本研究利用这一新的条件性基因编辑系统,分别对果蝇眼部white(w)基因和翅成虫盘broad(br)基因进行条件性敲除,观察到与预期相符的对应表型。因此,该条件性基因编辑系统在高效性、可扩展性和易操作性等方面是对现有CRISPR/Cas9系统进行的重大改进。展开更多
文摘Triplexers are designed based on SOl flattop arrayed waveguide gratings （AWGs）. Three wavelengths （1310, 1490,and 1550nm） operate at three diffraction orders of AWGs. Simulation shows that the 3dB bandwidth,crosstalk, and loss are 6nm,less than -40dB, and 5dB, respectively. The output optical fields of the device fabricated in our laboratory are clear and show a good triplexing function.
文摘We investigate an optical compact triplexer based on two photonic crystal waveguides and resonant cavities. For performing wavelength selection, we use three core-shell rods as the resonant cavities. The core rods are created by introducing air holes in the center of the silicon rods. By varying the radii of the air holes, three specific wavelengths 1.31, 1.49 and 1.55μm can be obtained. This structure is designed and its performance is verified by the finite-difference time-domain method, which is highly suitable for photonic integrated circuits （PICs）. The average output transmission efficiency and quality factor are more than 98.85% and 560, respectively. The mean value of the crosstalk between output channels is about -36.49 dB. The present device is extremely compact with total size 96.24μm2, which is suitable for PICs and can be utilized in the fiber-to-the-home system.
文摘In this work, we propose a new design of all-optical triplexer based on of metal–insulator–metal（MIM） plasmonic waveguide structures and ring resonators. By adjusting the radii of ring resonators and the gap distance, certain wavelengths can be filtered out and the crosstalk of each channel can also be reduced. The numerical results show that the proposed MIM plasmonic waveguide structure can really function as an optical triplexer with respect to the three wavelengths, that is, 1310, 1490, and 1550 nm, respectively. It can be widely used as the fiber access network element for multiplexer–demultiplexer wavelength selective in fiber-to-the-home communication systems with transmission efficiency higher than 90%. It can also be a potential key component in the applications of the biosensing systems.
基金financially supported by the National Key Research and Development Program of China(No.2021YFC2701402)the Open Research Fund of State Key Laboratory of Bioelectronics,Southeast University(No.Sklb2021-k06)+1 种基金the Open Foundation of NHC Key Laboratory of Birth Defect for Research and Prevention(Hunan Provincial Maternal and Child Health Care Hospital)(No.KF2020007)the Open Foundation of Translational Medicine National Science and Technology Infrastructure(Shanghai)(No.TMSK-2021-141)。
文摘Strand displacement reaction is a crucial component in the assembly of diverse DNA-based nanodevices,with the toehold-mediated strand displacement reaction representing the prevailing strategy.However,the single-stranded Watson-Crick sticky region that serves as the trigger for strand displacement can also cause leakage reactions by introducing crosstalk in complex DNA circuits.Here,we proposed the toeless and reversible DNA strand displacement reaction based on the Hoogsteen-bond triplex,which is compatible with most of the existing DNA circuits.We demonstrated that our proposed reaction can occur at pH 5 and can be reversed at pH 9.We also observed an approximately linear relationship between the degree of reaction and pH within the range of pH 5-6,providing the potential for precise regulation of the reaction.Meanwhile,by altering the sequence orientation,we have demonstrated that our proposed reaction can be initiated or regulated through the same toeless mechanism without the requirement for protonation in low pH conditions.Based on the proposed reaction principle,we further constructed a variety of DNA nanodevices,including two types of DNA logic gates that rely on pH 5/pH 9 changes for initiating and reversing:the AND gate and the OR gate.We also successfully constructed a DNA Walker based on our proposed reaction modes,which can move along a given track after the introduction of a programmable DNA sequence and complete a cycle after 4 steps.Our findings suggest that this innovative approach will have broad utility in the development of DNA circuits,molecular sensors,and other complex biological systems.
基金supported by the National Key R&D Program of China(Nos.2022YFC2804101,2020YFA0211200)National Natural Science Foundation of China(Nos.22377056,22222706,21977122)。
文摘The clustered regularly interspersed short palindromic repeats/CRISPR-associated protein 9(CRISPR/Cas9)system is an RNA-guided platform for highly efficient and specific genome targeting in diverse organisms,which has been exploited for various applications in gene manipulation.Compared with the constantly active CRISPR/Cas9 function,conditional control of its activity can improve the performance of the system with reduced side effects and high spatiotemporal precision.The pH-responsive triplex RNA was successful used in CRISPR-derived RNA/trans-activating crRNA(crRNA/tracrRNA)of CRISPR/Cas9,thus affecting RNA/dead Cas9(dCas9)complex to target DNA in vitro and in vivo.This design of triplex RNA opens a new window towards the broad involvement of eukaryotic cells for conditional control of CRISPR/Cas9function.?2024 Published by Elsevier B.V.on behalf of Chinese Chemical Society and Institute of Materia Medica,Chinese Academy of Medical Sciences.
基金the National Natural Science Foundation of China(No.81871732)the National Key Research and Development Program of China(No.2021YFC2701402)+4 种基金the Open Research Fund of State Key Laboratory of Bioelectronics,southeast University(No.Sklb2021-k06)the Open Foundation of NHC Key Laboratory of Birth Defect for Research and Prevention(Hunan Provincial Maternal and Child Health Care Hospital)(No.KF2020007)the Open Foundation of Translational Medicine National Science and Technology Infrastructure(Shanghai)(No.TMSK-2021-141)the Open Fund from Key Laboratory of Cellular Physiology(Shanxi Medical University)Ministry of Education,China(No.CPOF202103).
文摘DNA circuits are powerful tools in various applications such as logical computation,molecular diagnosis and synthetic biology.Leakage is a major problem in constructing complex DNA circuits.It directly affects the output signal and harms the circuit’s performance significantly.In the traditional DNA circuits,the gate complex is a duplex structure.There are insufficient energy barriers to prevent spontaneous detachment of strands,resulting in a leak prone.Herein,we have developed triplex-structure based DNA circuit with ultra-low leakage and high signal-to-noise ratio(SNR).The triplex structure improves the stability in the absence of input.At the same time,the driving force of the strand displacement cascades reduces the influence of the triplex structure on the desired reaction.The SNR of the DNA circuit was increased to 695,while the desired reaction rate remained 90%of the conventional translator circuit.The triplex-structure mediated leakage prevention strategy was further tested at different temperatures and in DNA translator and seesaw circuits.We also constructed modular basic logic gates with a high efficiency and low leakage.On this basis,we further constructed triplex-structure based tertiary DNA logic circuits,and the SNR reached 295,which,to the best of our knowledge,was among the highest of the field.We believe that our scheme provides a novel,valid,and general tool for reducing leakages,and we anticipate that it will be widely adopted in DNA nanotechnology.
基金financially supported by the National Natu-ral Science Foundation of China(Nos.52233018 and 51831002)。
文摘A novel Si-Al alloyed press hardening steel(PHS)with the ferrite(α)-austenite(γ)-martensite(α')triplex microstructure was developed to have marginal oxidization after the hot forming in air,and the resultant ultimate tensile strength(UTS)of 1620 MPa and total elongation(TE)of 14%were achieved simultaneously at reduced density.Both performances are superior to the existing PHSs.Particularly,the baking at 170°C leads to remarkable increases in both strength and ductility together with the transition of tensile fracture from the brittle interfacial cracking to the ductile one.This is because austenite and ferrite were hardened due to the segregation of C atoms into geometry necessary dislocations(GNDs)but martensite softened due to the loss of supersaturated C atoms during the baking.Atomic probe tomography examination reveals that some C atoms segregated to theα/α'interfaces during the baking for increased cohesive energy of the phase interface,thus hindering the interfacial cracking.In addition,the employed Al/Si alloying affords stronger oxidization resistance than both Al/Cr and Si/Cr because they are more rapidly oxidized than Cr to form the dense Al_(2) O_(3)/SiO_(2) layers for earlier protection.
文摘甲烷(CH4)是大气中最丰富的碳氢化合物,是仅次于二氧化碳(CO2)的温室气体。湿地是甲烷的重要来源,在全球碳循环中发挥着重要作用,其排放的甲烷占所有天然甲烷排放源的70%,占全球甲烷排放总量的24.8%。青藏高原平均海拔4000 m以上,占有中国约三分之一的湿地。近几十年来,由于全球气候变暖和降水增加,该地区甲烷排放率和湿地面积都发生着巨大变化,因此,青藏高原湿地CH4排放的长期变化在很大程度上仍存在较大的不确定性。利用TRIPLEX⁃GHG模型模拟了青藏高原湿地1978—2008年CH4排放的动态特征,研究结果表明:(1)1978—2008年青藏高原湿地CH4排放速率呈逐渐增加趋势。(2)青藏高原大多数湿地区域CH4排放速率为0—6.13 g CH4 m^-2a^-1;东北部分湿地区域CH4排放速率为6.14—20.19 g CH4 m^-2 a^-1;较高的CH4排放速率分布于青藏高原南部湿地区域,为56.14—74.97 g CH4 m^-2a^-1。(3)青藏高原湿地CH4排放量在1978、1990、2000年和2008年分别为0.21、0.23、0.27和0.32 Tg CH4 a^-1。在1978—1990年,尽管CH4排放速率增加,但湿地面积减少,因此这一时期青藏高原湿地CH4排放量并未发生明显变化。随后由于降水增加和冰川融化,使得湿地面积逐渐增加,青藏高原湿地CH4排放量也呈现增加趋势。
基金financial support from National Natural Science Foundation of China (Nos. 51861135302 and 51831002)the National Natural Science Foundation (No. 51904028)+2 种基金Fundamental Research Funds for the Central Universities (No. 06600019, 06500151)the Deutsche Forschungsgemeinschaft (DFG) for funding the research work (grant number BL 402/49–1, “Characterizing and modeling on microstructural evolution during intercritical annealing of high performance medium Mn steel”)the Powder Diffraction and Total Scattering Beamline P02.1 of PETRA III at DESY (Proposal No.: I-20191416)
文摘In this paper, we report the influence of cooling processes on the yielding behavior of a medium Mn steel(MMS) with triplex microstructure, i.e. austenite(γ), ferrite(α) and as-quenched martensite(α’). After the intercritical annealing(IA) at both 725℃ and 750℃, the steel was subjected to the two cooling processes, i.e. air cooling(AC) and water quenching(WQ). It exhibits the discontinuous yielding after the AC following the IA at 750℃ while the continuous yielding after the WQ. Compared with WQ process,both the dilatometry and the microstructural examinations show that the AC process leads to lower Ms temperature, larger retained austenite(RA) fraction and less martensite, the latter is always companied with geometry necessary dislocations(GNDs) generated near the α/α’ interfaces. Considering the complexity of nanosized tri-phases in this steel, the presence of martensite with key features in the resultant specimens was systematically examined by atom probe tomography(APT) on the samples prepared by the specific target lift-out method. The APT results directly revealed the C/Mn co-segregation at the α’/αinterfaces in the AC samples but not in WQ samples. The numerical simulation results further suggest that the segregation of C and Mn at the α’/α interfaces may be due to different mechanisms. We conclude that the yielding of triplex MMS is determined by both the quantity of GNDs generated near theα/α’ interfaces, which increases with martensite fraction, and the extent of their immobilization resulting from the interfacial segregation of solute atoms when the presence of martensite is sufficient. WQ tends to suppress the discontinuous yielding of MMS since the rapid cooling may promote more martensite formed with the increasing quantity of GNDs and prevent the interfacial segregation of both C and Mn.
基金financial support of the German Research Foundation(DFG)under the project AN 1245/1the support of the BMBF project‘Ker Solife100’the Helmholtz programme‘Renewable energies’(35.14.01)。
文摘Phase-field modelling of microstructural evolution in polycrystalline systems with phase-associated grains has largely been confined to continuum-field models.In this study,a multiphase-field approach,with a provision for introducing grain boundary and interphase diffusion,is extended to analyse concurrent grain growth and coarsening in multicomponent polycrystalline microstructures with chemically-distinct grains.The effect of the number of phases and components on the kinetics of evolution is investigated by considering binary and ternary systems of duplex and triplex microstructures,along with a single phase system.It is realised that the mere increase in the number of phases minimises the rate of concurrent grain growth and coarsening.However,the effect of components is substantially dependent on the respective kinetic coefficients.This work unravels that the disparity in the influence of phases and components is primarily due to the corresponding change introduced in the transformation mechanism.While the raise in number of phases convolutes the diffusion paths,the increase in number of component effects the rate of evolution through the interdiffusion,which introduces interdependency in the diffusing chemical-species.Additionally,the role of phase-fractions on the transformation rate of triplex microstructure is studied,and correspondingly,the interplay of interface-and diffusion-governed evolution is elucidated.A representative evolution of three-dimensional triplex microstructure with equal phase-fraction is comparatively analysed with the evolution of corresponding two-dimensional setup.
基金funded by the National Natural Science Foundation of China(No.31801620).
文摘Saxitoxin(STX),one of the most toxic paralytic shellfish poisons discovered to date,is listed as a required item of aquatic product safety inspection worldwide.However,conventional detection methods for STX are limited by various issues,such as low sensitivity,complicated operations,and ethical considerations.In this study,an aptamer-triplex molecular switch(APT-TMS)and gold nanoparticle(AuNP)nanozyme were combined to develop a label-free colorimetric aptasensor for the rapid and highly sensitive de-tection of STX.An anti-STX aptamer designed with pyrimidine arms and a purine chain was fabricated to form an APT-TMS.Specific binding between the aptamer and STX triggered the opening of the switch,which causes the purine chains to adsorb onto the surface of the AuNPs and enhances the peroxidase-like activity of the AuNP nanozyme toward 3,3’,5,5’-tetramethylbenzidine.Under optimized conditions,the proposed aptasensor showed high sensitivity and selectivity for STX,with a limit of detection of 335.6 pmol L^(−1) and a linear range of 0.59-150 nmol L^(−1).Moreover,good recoveries of 82.70%-92.66%for shellfish and 88.97%-106.5%for seawater were obtained.The analysis could be completed within 1 h.The proposed design also offers a robust strategy to achieve detection of other marine toxin targets by altering the corresponding aptamers.
文摘CRISPR/Cas9(clustered regularly interspaced short palindromic repeats(CRISPR)/CRISPR-associated protein 9)系统具有高效、简单、易编辑等特性,在基因工程方面具有巨大潜能。在果蝇(Drosophila melanogaster)基因功能研究中,CRISPR/Cas9系统也得到了广泛应用。然而利用传统的CRISPR/Cas9系统编辑果蝇基因时,Cas9与sgRNA表达元件往往分别存在于不同果蝇中,需要通过复杂的遗传杂交过程将Cas9与sgRNA整合到一个个体中,操作周期长且较为复杂。本研究在CRISPR/Cas9系统基础上引入tRNA-sgRNA系统和triplex元件,利用triplex元件连接Cas9和tRNA-sgRNA基因,稳定单转录本切割后Cas9 mRNA的末端,实现一个转录本可以同时表达Cas9蛋白和sgRNA,通过一次杂交即可得到相应表型的后代,简化了遗传操作过程。本研究利用这一新的条件性基因编辑系统,分别对果蝇眼部white(w)基因和翅成虫盘broad(br)基因进行条件性敲除,观察到与预期相符的对应表型。因此,该条件性基因编辑系统在高效性、可扩展性和易操作性等方面是对现有CRISPR/Cas9系统进行的重大改进。
