The effects of gradient nanostructures induced by supersonic fine particle bombardment(SFPB)on the surface integrity,microstructural evolution,and mechanical properties of a Ni-W-Co-Ta medium-heavy alloy(MHA)were syst...The effects of gradient nanostructures induced by supersonic fine particle bombardment(SFPB)on the surface integrity,microstructural evolution,and mechanical properties of a Ni-W-Co-Ta medium-heavy alloy(MHA)were systematically investigated.The results show that gradient nanostructures are formed on the surface of Ni-W-Co-Ta MHA after SFPB treatment.At a gas pressure of 1.0 MPa and an impact time of 60 s,the ultimate tensile strength and yield strength of the alloy reached the maximum values of 1236 MPa and 758 MPa,respectively,which are 22.5%and 38.8%higher than those of the solid solution treated alloy,and the elongation(46.3%)is close to that of the solid solution treated alloy,achieving the optimal strength–ductility synergy.However,microcracks appear on the surface with excessive gas pressure and impact time,generating the relaxed residual stress and decreased strength.With the increase of the impact time and gas pressure,the depth of the deformation layer and the surface microhardness gradually increase,reaching the maximum values(29μm and HV 451)at 1.0 MPa and 120 s.The surface grain size is refined to a minimum of 11.67 nm.Notably,SFPB treatment has no obvious effect on elongation,and the fracture mode changes from the ductile fracture before treatment to ductile–brittle mixed fracture after treatment.展开更多
In this paper,a white organic light-emitting device(WOLEDs) with multiple-emissive-layer structure has been fabricated.The device has a simple structure of indium tin oxide(ITO)/NPB(20 nm)//DPVBi(20 nm)/CDBP:x Ir(btp)...In this paper,a white organic light-emitting device(WOLEDs) with multiple-emissive-layer structure has been fabricated.The device has a simple structure of indium tin oxide(ITO)/NPB(20 nm)//DPVBi(20 nm)/CDBP:x Ir(btp)2acac(10 nm)/Alq3(25 nm)/BCP(5 nm)/Cs F(1 nm)/Al(150 nm)(x= 0.15,2.5 and 3.0 wt%),where NPB and BCP are used as the hole-injecting layer,electron transporting and hole blocking layer,respectively.White light emission was realized in an OLED with 2.5% Ir(btp)2acac doping concentration.The device exhibits peak efficiency of 1.93 cd/A at 9 V and maximum brightness of 7005 cd/m^2 at 14 V.The Commission International de I'Eclairage(CIE)(1931) coordinates of white emission are well within the white zone,which moves from(0.35,0.33) to(0.26,0.30) when the applied voltage is varied from 5 V to 14 V.展开更多
Three different types of TiO2 nano powders were synthesized by a solution combustion synthesis （SCS） method using three different fuels and for comparison, another type of Ti2 nano powder was synthesized by calcinat...Three different types of TiO2 nano powders were synthesized by a solution combustion synthesis （SCS） method using three different fuels and for comparison, another type of Ti2 nano powder was synthesized by calcination of titanyl hydroxide. These TiO2 nano powders were used to fabricate photoelectrodes for the dye-sensitized solar cell （DSSC） and their performance was compared to that of the DSSC fabricated with Degussa P25 TiO2. The results showed that the SCS TiO2 could work well as photoelectrode for DSSC. The SCS TiO2 contained impurities of C and/or S, thus exhibiting visible light absorption and reduced band gap. The open circuit voltage and the fill factor both varied little among the various TiO2 and thus both had little effect on the photoelectrical conversion efficiency （η）. However, the variation of r/was seen to be in quite a good agreement with that of the short circuit current （Isc）, suggesting that r/was dominated by Isc. lsc was found to be enhanced by light scattering effect due to the presence of large particles but reduced by high impurity content due to an increase in electron transfer resistance. In addition, the specific surface area of the powders was found to be an important factor affecting the Isc and thus the η.展开更多
The performance of polymer light emitting devices(PLEDs)based on polyvinyl carbazole(PVK)is improved by introducing a nanoscale interfacial thin layer,made of poly(ethylene oxide)(PEO),between the calcium cathode and ...The performance of polymer light emitting devices(PLEDs)based on polyvinyl carbazole(PVK)is improved by introducing a nanoscale interfacial thin layer,made of poly(ethylene oxide)(PEO),between the calcium cathode and the PVK emissive layer.It is believed that the PEO layer plays a key role in enhancing the device performance.In comparison to the device with Ca/Al as the cathode,the performance of the PLED with PEO/Ca/Al cathode,including the driving voltage,luminance efficiency is significantly improved.These improvements are attributed to the introduction of a thin layer of PEO that can lower the interfacial barrier and facilitate electron injection.展开更多
In this paper we design a new kind of sinc-sampled fiber Bragg grating which is fabricated in high birefringence fiber (HBF). The sampled grating has two sets of reflection spectra along two perpendicular polarization...In this paper we design a new kind of sinc-sampled fiber Bragg grating which is fabricated in high birefringence fiber (HBF). The sampled grating has two sets of reflection spectra along two perpendicular polarization directions. The grating's channel number can be doubled approximately by designing the refractive index difference between the fast and slow axes of the fiber, which enhances the utilization ratio and reduces the claim for photosensitivity of the fiber. The group delay characteristics are theoretically studied and side-lobes are depressed by apodization as well to get the optimized spectra. The results show that the comb-like spectra of the grating have promising applications in both multi-wavelength polarized fiber lasers and fiber sensing networks.展开更多
We report on a novel architecture to suppress the multi-pulse formation in an all-polarization-maintaining figure-9 erbium-doped fiber laser under high pump power. A 2×2 fiber coupler is introduced into the phase...We report on a novel architecture to suppress the multi-pulse formation in an all-polarization-maintaining figure-9 erbium-doped fiber laser under high pump power. A 2×2 fiber coupler is introduced into the phase-biased nonlinear amplifying loop mirror to extract part of intracavity laser power as a laser output, and the dependence of output couple ratio of fiber coupler on the mode-locking state is experimentally investigated. The intracavity nonlinear effect is mitigated by lowering the intracavity laser power, which is conducive to avoiding the multi-pulse formation. In the meantime, the loss-imbalance induced by fiber coupler is helpful in improving the self-starting ability. With the proposed laser structure,the multiple pulse formation can be suppressed and high power single pulse train can be obtained. The laser emits three pulse trains which is convenient for some applications. Finally, the output power values of three ports are 5.3 m W, 51.3 m W,and 13.2 m W, respectively. The total single pulse output power is 69.8 m W, which is more than 10 times the result without OC2. The total slope efficiency is about 10.1%. The repetition rate of three pulse trains is 21.17 MHz, and the pulse widths are 2.8 ps, 2.63 ps, and 6.66 ps, respectively.展开更多
Unraveling the mechanism underlying topological phases, notably the Chern insulators(Ch Is) in strong correlated systems at the microscopy scale, has captivated significant research interest. Nonetheless, Ch Is harbor...Unraveling the mechanism underlying topological phases, notably the Chern insulators(Ch Is) in strong correlated systems at the microscopy scale, has captivated significant research interest. Nonetheless, Ch Is harboring topological information have not always manifested themselves, owing to the constraints imposed by displacement fields in certain experimental configurations. In this study, we employ density-tuned scanning tunneling microscopy(DT-STM) to investigate the Ch Is in twisted monolayer–bilayer graphene(t MBG). At zero magnetic field, we observe correlated metallic states.While under a magnetic field, a metal–insulator transition happens and an integer Ch I is formed emanating from the filling index s = 3 with a Chern number C = 1. Our results underscore the pivotal role of magnetic fields as a powerful probe for elucidating topological phases in twisted Van der Waals heterostructures.展开更多
We investigated optically controllable gray-level diffraction from a body-centered tetragonal photonic crystal that was based on an azo-dye-doped holographic polymer dispersed liquid crystal. The sample is fabricated ...We investigated optically controllable gray-level diffraction from a body-centered tetragonal photonic crystal that was based on an azo-dye-doped holographic polymer dispersed liquid crystal. The sample is fabricated by use of two-beam interference with multi-exposure. Bichromatic pumping beams at various intensities were used to pump the sample to change the concentration of the cis isomer and, in turn, modulate the effective index of the photonic crystals as well as their diffraction intensity. Three pumping processes were utilized to produce gray-level switching of diffractive light. This study demonstrates the optimum gray-level to be 15-level of up-step and down-step. The simulation of the diffraction intensity under bichromatic pumping sources was also studied.展开更多
Twisted graphene systems with flat bands have attracted much attention for they are excellent platforms to research novel quantum phases. Recently, transport measurements about twisted monolayer–bilayer graphene(t MB...Twisted graphene systems with flat bands have attracted much attention for they are excellent platforms to research novel quantum phases. Recently, transport measurements about twisted monolayer–bilayer graphene(t MBG) have shown the existence of correlated states and topological states in this system. However, the direct observations of the band structures and the corresponding spatial distributions are still not sufficient. Here we show that the distributions of flat bands in t MBG host two different modes by scanning tunneling microscopy and spectroscopy(STM/S). By tuning our t MBG device from the empty filling state to the full filling state through the back gate, we observe that the distributions of two flat bands develop from localized mode to delocalized mode. This gate-controlled flat band wavefunction polarization is unique to the t MBG system. Our work suggests that t MBG is promising to simulate both twisted bilayer graphene(TBG) and twisted double bilayer graphene(t DBG) and would be an ideal platform to explore novel moiré physics.展开更多
A simple, low cost method for mass production to enhance the light extraction efficiency of GaN-related LEDs was proposed. With appropriate process parameters, the nature lithography of nanosphere can be used to fabri...A simple, low cost method for mass production to enhance the light extraction efficiency of GaN-related LEDs was proposed. With appropriate process parameters, the nature lithography of nanosphere can be used to fabricate two-dimensional nanostructures, including the nanomesh ZnO layer, photonic crystal (PhC) patterned p-GaN, and patterned sapphire substrates. Based on preliminary results, the extraction efficiencies of LEDs with these nanostructures can thus be improved and the nature lithography is demonstrated to be a promising method to be widely exploited in the manufacture of all kinds of LED devices.展开更多
As immunotoxicity assessments of newly developed biomaterials are often restricted to use in assessment of local tissue response at the implantation site,they do not always show an immune response acceptable to qualif...As immunotoxicity assessments of newly developed biomaterials are often restricted to use in assessment of local tissue response at the implantation site,they do not always show an immune response acceptable to qualify them for clinical use.We tested a new method to assess systemic toxicity:counting the CD4^(+) and CD8^(+) cells in the spleen.Three different biomaterials were subcutaneously implanted in three groups of rats for the same time period.After 31 days,their spleens were harvested,and CD4^(+) and CD8^(+) cells were counted.The mean CD4^(+)/CD8^(+) cell counts were 24.563.6/19.864.0(porous collagen matrix group),25.567.1/21.663.8[synthetic collagen matrix(DuragenVR)group]and 28.164.1/19.663.7(porcine dermis group).Differences in cell counts were not significant.The immunotoxic response generated against porous collagen matrix was comparable to that produced by a similar biomaterial already used clinically.This is,to the best of our knowledge,the first study on cytotoxic lymphocytes in the spleen to quantify systemic immune response to a biomaterial;however,such studies have been conducted with bacterial and viral antigens,and with vaccines.We believe that the present study provides a viable method for larger studies to confirm our current findings.展开更多
Oxygen anion redox chemistry in layered oxide cathodes for sodium-ion batteries has attracted great interest.However,the release of lattice oxygen caused by the irreversible anionic redox and Jahn–Teller effect accel...Oxygen anion redox chemistry in layered oxide cathodes for sodium-ion batteries has attracted great interest.However,the release of lattice oxygen caused by the irreversible anionic redox and Jahn–Teller effect accelerates the structural distortion and electrochemical degradation.Herein,we rationally construct a stable crystal lattice to enhance the reactivity and reversibility of oxygen redox and inhibit the Jahn–Teller effect by Sn doping.The stronger binding energy of Sn–O enhances the structural stability of the cathode,which is favorable to suppress the oxygen release and Jahn–Teller effect.Thus,the reversibility of oxygen redox and the stability of the layered structure are enhanced.The expansion of the interlayer spacing decreases the energy barriers for Na+ion intercalation,improving the rate performance of the electrode.Benefitting from the rational design,the electrode delivers an enhanced rate performance and cycling stability.This work offers some insights into tuning the oxygen anion redox chemistry as well as suppressing the Jahn–Teller effect by lattice modulation.展开更多
A convex aspheric surface using a computer-generated hologram （CGH） test plate fabricated with novel techniques and equipment is tested. However, the measurement result is not verified via comparison with other meth...A convex aspheric surface using a computer-generated hologram （CGH） test plate fabricated with novel techniques and equipment is tested. However, the measurement result is not verified via comparison with other methods. To verify the accuracy of the measurement, a perfect sphere surface is measured by the following. The measurement result is quantified into four parts： the figure error from the tested spherical surface; the figure error from the reference spherical surface; the error from the hologram; and the adjustment error from misalignment. The measurement result, removed from the later three errors, shows agreement to 4-nm RMS with the test by Zygo interfermeter of the same surface. Analysis of the CGH test showed the overall accuracy of the 4-nm RMS, with 3.9 nm from the test plate figure, 0.5 nm from the hologram, and 0.74 nm from other sources, such as random vibration, various second order effects, and so on. Thus, the measurement accuracy using the proposed CGH could be very high. CGH can therefore be used to measure aspheric surfaces accurately.展开更多
The effect of chalcogen heteroatom variation on donor materials has been systematically investigated. However, this effect on acceptors has rarely been explored. Herein, nonfullerene acceptors BFPSP and BFPTP were rep...The effect of chalcogen heteroatom variation on donor materials has been systematically investigated. However, this effect on acceptors has rarely been explored. Herein, nonfullerene acceptors BFPSP and BFPTP were reported by simply changing the chalcogen atoms from S to Te. The differences between BFPSP and BFPTP in light absorption, energy levels, excited-state lifetimes, energy loss, charge mobilities, morphology, and photovoltaic properties were systematically investigated to understand the heteroatom effects. More importantly, the electroluminescence spectra, external quantum efficiency of photovoltaics and TDDFTcalculations revealed that the triplet excited state(T1) in energy of BFPTP equals to the charge transfer(CT) state in PBDBT:BFPTP, which allows T1 excitons, generated by intersystem crossing, to split into free charges to contribute to the efficiency.This contribution provides a strategy for tuning the photophysical properties of nonfullerene acceptors and designing high performance triplet materials for OSCs.展开更多
K-ion batteries(KIBs)hold great promise for large-scale energy storage.However,the absence of suitable cathode materials limits their practical application.Meanwhile,rationally designing advanced cathode materials for...K-ion batteries(KIBs)hold great promise for large-scale energy storage.However,the absence of suitable cathode materials limits their practical application.Meanwhile,rationally designing advanced cathode materials for KIBs remains an open question.In this work,based on density functional theory calculations,we find that the bond stability of Fe–O is higher than that of Co–O in layered transitional metal(TM)oxides.Additionally,the K-ion migration in the Fe-based layered TM oxide has a significantly lower activation energy barrier than that in the Co-based one.Based on this theoretical prediction,we successfully synthesized a low-cost K_(0.45)Ni_(0.1)Fe_(0.1)Mn_(0.8)O_(2)cathode,which shows excellent structural stability and superior K-storage properties,including durable cycle life and high-rate capability.Moreover,the designed K_(0.45)Ni_(0.1)Fe_(0.1)Mn_(0.8)O_(2)cathode possesses a great full-cell performance with a discharge capacity of~75 mA h g^(-1) and capacity retention of~80%after 100 cycles.The results show that Fe has better structural stability and K-ion diffusion than high-cost Co in layered oxide cathodes,and this finding provides new insights into the design of low-cost and high-performance KIB layered cathodes.This work highlights the feasibility of a theory-guided experiment in screening promising battery materials.展开更多
基金supported by the National key Research and Development Program of China(No.2022YFB3705200)the National Natural Science Foundation of China(Nos.U1804146,51905153,52111530068)+1 种基金the Science and Technology Innovation Team Project of Henan University of Science and Technology,China(No.2015XTD006)the Major Science and Technology Project of Henan Province,China(No.221100230200)。
文摘The effects of gradient nanostructures induced by supersonic fine particle bombardment(SFPB)on the surface integrity,microstructural evolution,and mechanical properties of a Ni-W-Co-Ta medium-heavy alloy(MHA)were systematically investigated.The results show that gradient nanostructures are formed on the surface of Ni-W-Co-Ta MHA after SFPB treatment.At a gas pressure of 1.0 MPa and an impact time of 60 s,the ultimate tensile strength and yield strength of the alloy reached the maximum values of 1236 MPa and 758 MPa,respectively,which are 22.5%and 38.8%higher than those of the solid solution treated alloy,and the elongation(46.3%)is close to that of the solid solution treated alloy,achieving the optimal strength–ductility synergy.However,microcracks appear on the surface with excessive gas pressure and impact time,generating the relaxed residual stress and decreased strength.With the increase of the impact time and gas pressure,the depth of the deformation layer and the surface microhardness gradually increase,reaching the maximum values(29μm and HV 451)at 1.0 MPa and 120 s.The surface grain size is refined to a minimum of 11.67 nm.Notably,SFPB treatment has no obvious effect on elongation,and the fracture mode changes from the ductile fracture before treatment to ductile–brittle mixed fracture after treatment.
文摘In this paper,a white organic light-emitting device(WOLEDs) with multiple-emissive-layer structure has been fabricated.The device has a simple structure of indium tin oxide(ITO)/NPB(20 nm)//DPVBi(20 nm)/CDBP:x Ir(btp)2acac(10 nm)/Alq3(25 nm)/BCP(5 nm)/Cs F(1 nm)/Al(150 nm)(x= 0.15,2.5 and 3.0 wt%),where NPB and BCP are used as the hole-injecting layer,electron transporting and hole blocking layer,respectively.White light emission was realized in an OLED with 2.5% Ir(btp)2acac doping concentration.The device exhibits peak efficiency of 1.93 cd/A at 9 V and maximum brightness of 7005 cd/m^2 at 14 V.The Commission International de I'Eclairage(CIE)(1931) coordinates of white emission are well within the white zone,which moves from(0.35,0.33) to(0.26,0.30) when the applied voltage is varied from 5 V to 14 V.
基金Support of this research by the National Science Council of Taiwan under Grant No. NSC 100-2221-E-006-214partial support under Contract No. 101-D0204-6 by the Bureau of Energy, Ministry of Economic Affairs of Taiwanthe LED Lighting Research Center, NCKU
文摘Three different types of TiO2 nano powders were synthesized by a solution combustion synthesis （SCS） method using three different fuels and for comparison, another type of Ti2 nano powder was synthesized by calcination of titanyl hydroxide. These TiO2 nano powders were used to fabricate photoelectrodes for the dye-sensitized solar cell （DSSC） and their performance was compared to that of the DSSC fabricated with Degussa P25 TiO2. The results showed that the SCS TiO2 could work well as photoelectrode for DSSC. The SCS TiO2 contained impurities of C and/or S, thus exhibiting visible light absorption and reduced band gap. The open circuit voltage and the fill factor both varied little among the various TiO2 and thus both had little effect on the photoelectrical conversion efficiency （η）. However, the variation of r/was seen to be in quite a good agreement with that of the short circuit current （Isc）, suggesting that r/was dominated by Isc. lsc was found to be enhanced by light scattering effect due to the presence of large particles but reduced by high impurity content due to an increase in electron transfer resistance. In addition, the specific surface area of the powders was found to be an important factor affecting the Isc and thus the η.
基金the Office of R&D,National Cheng Kung University,Taiwan
文摘The performance of polymer light emitting devices(PLEDs)based on polyvinyl carbazole(PVK)is improved by introducing a nanoscale interfacial thin layer,made of poly(ethylene oxide)(PEO),between the calcium cathode and the PVK emissive layer.It is believed that the PEO layer plays a key role in enhancing the device performance.In comparison to the device with Ca/Al as the cathode,the performance of the PLED with PEO/Ca/Al cathode,including the driving voltage,luminance efficiency is significantly improved.These improvements are attributed to the introduction of a thin layer of PEO that can lower the interfacial barrier and facilitate electron injection.
基金supported by the Natural Science Funds of Shandong Province (No.Q2007G03)the Independent Innovation Fund of Shandong University (No.2010TS014)the Open Fund of Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), Ministry of Education
文摘In this paper we design a new kind of sinc-sampled fiber Bragg grating which is fabricated in high birefringence fiber (HBF). The sampled grating has two sets of reflection spectra along two perpendicular polarization directions. The grating's channel number can be doubled approximately by designing the refractive index difference between the fast and slow axes of the fiber, which enhances the utilization ratio and reduces the claim for photosensitivity of the fiber. The group delay characteristics are theoretically studied and side-lobes are depressed by apodization as well to get the optimized spectra. The results show that the comb-like spectra of the grating have promising applications in both multi-wavelength polarized fiber lasers and fiber sensing networks.
基金Project supported by the National Natural Science Foundation of China(Grant No.51905528)the Key Research Project of Bureau of Frontier Sciences and Education+1 种基金Chinese Academy of Sciences(Grant No.QYZDY-SSW-JSC008)the National Key Research and Development Project,China(Grant Nos.2019YFB2005600 and 2018YFB2003403)。
文摘We report on a novel architecture to suppress the multi-pulse formation in an all-polarization-maintaining figure-9 erbium-doped fiber laser under high pump power. A 2×2 fiber coupler is introduced into the phase-biased nonlinear amplifying loop mirror to extract part of intracavity laser power as a laser output, and the dependence of output couple ratio of fiber coupler on the mode-locking state is experimentally investigated. The intracavity nonlinear effect is mitigated by lowering the intracavity laser power, which is conducive to avoiding the multi-pulse formation. In the meantime, the loss-imbalance induced by fiber coupler is helpful in improving the self-starting ability. With the proposed laser structure,the multiple pulse formation can be suppressed and high power single pulse train can be obtained. The laser emits three pulse trains which is convenient for some applications. Finally, the output power values of three ports are 5.3 m W, 51.3 m W,and 13.2 m W, respectively. The total single pulse output power is 69.8 m W, which is more than 10 times the result without OC2. The total slope efficiency is about 10.1%. The repetition rate of three pulse trains is 21.17 MHz, and the pulse widths are 2.8 ps, 2.63 ps, and 6.66 ps, respectively.
文摘Unraveling the mechanism underlying topological phases, notably the Chern insulators(Ch Is) in strong correlated systems at the microscopy scale, has captivated significant research interest. Nonetheless, Ch Is harboring topological information have not always manifested themselves, owing to the constraints imposed by displacement fields in certain experimental configurations. In this study, we employ density-tuned scanning tunneling microscopy(DT-STM) to investigate the Ch Is in twisted monolayer–bilayer graphene(t MBG). At zero magnetic field, we observe correlated metallic states.While under a magnetic field, a metal–insulator transition happens and an integer Ch I is formed emanating from the filling index s = 3 with a Chern number C = 1. Our results underscore the pivotal role of magnetic fields as a powerful probe for elucidating topological phases in twisted Van der Waals heterostructures.
文摘We investigated optically controllable gray-level diffraction from a body-centered tetragonal photonic crystal that was based on an azo-dye-doped holographic polymer dispersed liquid crystal. The sample is fabricated by use of two-beam interference with multi-exposure. Bichromatic pumping beams at various intensities were used to pump the sample to change the concentration of the cis isomer and, in turn, modulate the effective index of the photonic crystals as well as their diffraction intensity. Three pumping processes were utilized to produce gray-level switching of diffractive light. This study demonstrates the optimum gray-level to be 15-level of up-step and down-step. The simulation of the diffraction intensity under bichromatic pumping sources was also studied.
基金support from the National Key R&D Program of China (Grant No. 2019YFA0307800)Beijing Natural Science Foundation (Grant No. Z190011)+1 种基金the National Natural Science Foundation of China (Grant No. 11974347)Fundamental Research Funds for the Central Universities。
文摘Twisted graphene systems with flat bands have attracted much attention for they are excellent platforms to research novel quantum phases. Recently, transport measurements about twisted monolayer–bilayer graphene(t MBG) have shown the existence of correlated states and topological states in this system. However, the direct observations of the band structures and the corresponding spatial distributions are still not sufficient. Here we show that the distributions of flat bands in t MBG host two different modes by scanning tunneling microscopy and spectroscopy(STM/S). By tuning our t MBG device from the empty filling state to the full filling state through the back gate, we observe that the distributions of two flat bands develop from localized mode to delocalized mode. This gate-controlled flat band wavefunction polarization is unique to the t MBG system. Our work suggests that t MBG is promising to simulate both twisted bilayer graphene(TBG) and twisted double bilayer graphene(t DBG) and would be an ideal platform to explore novel moiré physics.
基金the "National" Science Council for finan-cially supporting this research under contract No. NSC 96-2221-E-006-079-MY3 and NSC 98-2218-E-006-005-MY2supported by TDPA program (Grant No. TDPA 97-EC-17-A-07-S1-105)
文摘A simple, low cost method for mass production to enhance the light extraction efficiency of GaN-related LEDs was proposed. With appropriate process parameters, the nature lithography of nanosphere can be used to fabricate two-dimensional nanostructures, including the nanomesh ZnO layer, photonic crystal (PhC) patterned p-GaN, and patterned sapphire substrates. Based on preliminary results, the extraction efficiencies of LEDs with these nanostructures can thus be improved and the nature lithography is demonstrated to be a promising method to be widely exploited in the manufacture of all kinds of LED devices.
文摘As immunotoxicity assessments of newly developed biomaterials are often restricted to use in assessment of local tissue response at the implantation site,they do not always show an immune response acceptable to qualify them for clinical use.We tested a new method to assess systemic toxicity:counting the CD4^(+) and CD8^(+) cells in the spleen.Three different biomaterials were subcutaneously implanted in three groups of rats for the same time period.After 31 days,their spleens were harvested,and CD4^(+) and CD8^(+) cells were counted.The mean CD4^(+)/CD8^(+) cell counts were 24.563.6/19.864.0(porous collagen matrix group),25.567.1/21.663.8[synthetic collagen matrix(DuragenVR)group]and 28.164.1/19.663.7(porcine dermis group).Differences in cell counts were not significant.The immunotoxic response generated against porous collagen matrix was comparable to that produced by a similar biomaterial already used clinically.This is,to the best of our knowledge,the first study on cytotoxic lymphocytes in the spleen to quantify systemic immune response to a biomaterial;however,such studies have been conducted with bacterial and viral antigens,and with vaccines.We believe that the present study provides a viable method for larger studies to confirm our current findings.
基金the National Natural Science Foundation of China(grant nos.11975238 and 11575192)the Chinese Academy of Sciences(grant nos.ZDKYYQ20170001,211211KYSB20170060,and 211211KYSB20180020)the Natural Science Foundation of Beijing Municipality(grant no.2182082).
文摘Oxygen anion redox chemistry in layered oxide cathodes for sodium-ion batteries has attracted great interest.However,the release of lattice oxygen caused by the irreversible anionic redox and Jahn–Teller effect accelerates the structural distortion and electrochemical degradation.Herein,we rationally construct a stable crystal lattice to enhance the reactivity and reversibility of oxygen redox and inhibit the Jahn–Teller effect by Sn doping.The stronger binding energy of Sn–O enhances the structural stability of the cathode,which is favorable to suppress the oxygen release and Jahn–Teller effect.Thus,the reversibility of oxygen redox and the stability of the layered structure are enhanced.The expansion of the interlayer spacing decreases the energy barriers for Na+ion intercalation,improving the rate performance of the electrode.Benefitting from the rational design,the electrode delivers an enhanced rate performance and cycling stability.This work offers some insights into tuning the oxygen anion redox chemistry as well as suppressing the Jahn–Teller effect by lattice modulation.
基金supported by the National Natural Science Foundation of China under Grand No.61137001
文摘A convex aspheric surface using a computer-generated hologram （CGH） test plate fabricated with novel techniques and equipment is tested. However, the measurement result is not verified via comparison with other methods. To verify the accuracy of the measurement, a perfect sphere surface is measured by the following. The measurement result is quantified into four parts： the figure error from the tested spherical surface; the figure error from the reference spherical surface; the error from the hologram; and the adjustment error from misalignment. The measurement result, removed from the later three errors, shows agreement to 4-nm RMS with the test by Zygo interfermeter of the same surface. Analysis of the CGH test showed the overall accuracy of the 4-nm RMS, with 3.9 nm from the test plate figure, 0.5 nm from the hologram, and 0.74 nm from other sources, such as random vibration, various second order effects, and so on. Thus, the measurement accuracy using the proposed CGH could be very high. CGH can therefore be used to measure aspheric surfaces accurately.
基金supported by the National Natural Science Foundation of China(21774130,21673054)the National Key Research and Development Program of China(2018FYA 0305800)+6 种基金the Key Research Program of Frontier Sciences,CAS(QYZDB-SSW-JSC046)Key Research Program of the Chinese Academy of Sciences(XDPB08-2)the Strategic Priority Research Program of Chinese Academy of Sciences(XDB28000000,XDB12020200)External Cooperation Programs of Chinese Academy of Sciences(211211KYSB20170014)Innovation Program of Aerospace Science and Technology,China Aerospace Science and Technology CorporationOne Hundred Talents Program of Chinese Academy of Sciences,and University of Chinese Academy of Sciences,the Ministry of Science and Technology(2017YFA0205004,2016YFA0200700)Beijing Natural Research Foundation(4182076)
文摘The effect of chalcogen heteroatom variation on donor materials has been systematically investigated. However, this effect on acceptors has rarely been explored. Herein, nonfullerene acceptors BFPSP and BFPTP were reported by simply changing the chalcogen atoms from S to Te. The differences between BFPSP and BFPTP in light absorption, energy levels, excited-state lifetimes, energy loss, charge mobilities, morphology, and photovoltaic properties were systematically investigated to understand the heteroatom effects. More importantly, the electroluminescence spectra, external quantum efficiency of photovoltaics and TDDFTcalculations revealed that the triplet excited state(T1) in energy of BFPTP equals to the charge transfer(CT) state in PBDBT:BFPTP, which allows T1 excitons, generated by intersystem crossing, to split into free charges to contribute to the efficiency.This contribution provides a strategy for tuning the photophysical properties of nonfullerene acceptors and designing high performance triplet materials for OSCs.
基金supported by the Fundamental Research Funds for the Central Universities and the Scientific Instrument Developing Project of the Chinese Academy of Sciences(ZDKYYQ20170001)。
文摘K-ion batteries(KIBs)hold great promise for large-scale energy storage.However,the absence of suitable cathode materials limits their practical application.Meanwhile,rationally designing advanced cathode materials for KIBs remains an open question.In this work,based on density functional theory calculations,we find that the bond stability of Fe–O is higher than that of Co–O in layered transitional metal(TM)oxides.Additionally,the K-ion migration in the Fe-based layered TM oxide has a significantly lower activation energy barrier than that in the Co-based one.Based on this theoretical prediction,we successfully synthesized a low-cost K_(0.45)Ni_(0.1)Fe_(0.1)Mn_(0.8)O_(2)cathode,which shows excellent structural stability and superior K-storage properties,including durable cycle life and high-rate capability.Moreover,the designed K_(0.45)Ni_(0.1)Fe_(0.1)Mn_(0.8)O_(2)cathode possesses a great full-cell performance with a discharge capacity of~75 mA h g^(-1) and capacity retention of~80%after 100 cycles.The results show that Fe has better structural stability and K-ion diffusion than high-cost Co in layered oxide cathodes,and this finding provides new insights into the design of low-cost and high-performance KIB layered cathodes.This work highlights the feasibility of a theory-guided experiment in screening promising battery materials.
