Organic afterglow materials are highly desirable for optoelectronic applications,but they usually suffer from complex preparation process,low quantum efficiency,and short lifetime due to the ultrafast deactivation of ...Organic afterglow materials are highly desirable for optoelectronic applications,but they usually suffer from complex preparation process,low quantum efficiency,and short lifetime due to the ultrafast deactivation of the highly active excited states involved.Here,we succeeded in achieving solventfree thermal syntheses of high-efficiency afterglow CDs@zeolite composite materials by simply grinding the solid raw materials of zeolite and precursor CDs at room temperature,followed by thermal crystallization.This method afforded maximum embedding of CDs into growing zeolite crystals,as well as strong host–guest interaction to surpass the nonradiative transition of CDs,thus producing composite materials with ultralong dual emission of thermally activated delayed fluorescence and room temperature phosphorescence with a record high lifetime of 1.7 and 2.1 s,respectively,and the quantum yield of 90.7%.Furthermore,in a preliminary experiment,we applied the composite materials in alternatingcurrent light-emitting diode supplementary lighting,which exhibited a promising potential in optoelectronic applications.展开更多
A new method for the determination of aniline in environmental water based on oscillopolarographic titration was presented in this paper. Several factors including the kind, concentration, and volume of acid, the dosa...A new method for the determination of aniline in environmental water based on oscillopolarographic titration was presented in this paper. Several factors including the kind, concentration, and volume of acid, the dosage of potassium bromide, the temperature and concentration of concomitant substances were investigated in detail. The experimental results indicated that this method was simple, rapid, and sensitive. The linear range was 8.367 × 10(?4) to 2.789 × 10(?2) mol L(?1), the relative standard deviation (R.S.D.) was lower than 0.96%, and the spiked recoveries of aniline in environmental water samples were in the range of 99.4–106.9% under the optimal conditions. The results indicated that the present method could be used as an alternative method for aniline determination in realworld water samples.展开更多
Dielectric barrier discharge(DBD)plasma excited by a high-frequency alternating-current(AC)power supply is widely employed for the degradation of volatile organic compounds(VOCs).However,the thermal effect generated d...Dielectric barrier discharge(DBD)plasma excited by a high-frequency alternating-current(AC)power supply is widely employed for the degradation of volatile organic compounds(VOCs).However,the thermal effect generated during the discharge process leads to energy waste and low energy utilization efficiency.In this work,an innovative DBD thermally-conducted catalysis(DBD-TCC)system,integrating high-frequency AC-DBD plasma and its generated thermal effects to activate the Co/SBA-15 catalyst,was employed for toluene removal.Specifically,Co/SBA-15 catalysts are closely positioned to the ground electrode of the plasma zone and can be heated and activated by the thermal effect when the voltage exceeds 10 k V.At12.4 k V,the temperature in the catalyst zone reached 261℃ in the DBD-TCC system,resulting in an increase in toluene degradation efficiency of 17%,CO_(2)selectivity of 21.2%,and energy efficiency of 27%,respectively,compared to the DBD system alone.In contrast,the DBD thermally-unconducted catalysis(DBD-TUC)system fails to enhance toluene degradation due to insufficient heat absorption and catalytic activation,highlighting the crucial role of AC-DBD generated heat in the activation of the catalyst.Furthermore,the degradation pathway and mechanism of toluene in the DBD-TCC system were hypothesized.This work is expected to provide an energy-efficient approach for high-frequency AC-DBD plasma removal of VOCs.展开更多
The perturbation method is used to study the localization of electric field distribution and the effective nonlinear response of graded composites under an external alternating-current（AC） and direct-current（DC） e...The perturbation method is used to study the localization of electric field distribution and the effective nonlinear response of graded composites under an external alternating-current（AC） and direct-current（DC） electric field E app = E 0（1 ＋ sin ωt）.The dielectric profile of the cylindrical inclusions is modeled by function ε i（r） = C k r k（r ≤ a）,where r is the radius of the cylindrical inclusion,and C k,k,a are parameters.In the dilute limit,the local potentials and the effective nonlinear responses at all harmonics are derived.Meanwhile,the general effective nonlinear responses are also derived and compared with the effective nonlinear responses at harmonics under the AC and DC external field.It is found that the effective nonlinear AC and DC responses at harmonics can be calculated by those of the general effective nonlinear of the graded composites under the external DC electric field.Moreover,the obtained local electrical fields show that the electrical field distribution in the cylindrical inclusions is controllable,and the maximum of the electric field inside the cylinder is at its center.展开更多
Alternating-current losses in a two-layer superconducting cable, each layer being composed of 15 closely-spaced rectangular wires made up of second-generation superconductors when the ends of wires are coated by eithe...Alternating-current losses in a two-layer superconducting cable, each layer being composed of 15 closely-spaced rectangular wires made up of second-generation superconductors when the ends of wires are coated by either a non-magnetic or strong ferromagnetic material having a U profile is numerically investigated. Computations are carried out through the finite-element method. The alternating-current losses do not increase significantly if the relative permeability of the coating is increased three orders of magnitude, provided that the current amplitude is less than half of the critical current in a superconducting wire. However, the losses are much higher for ferromagnetic coating if the amplitude of the applied current oscillating at 50 Hz is close to the critical current. The ferromagnetic coating is seen to accumulate the magnetic field lines normally on its surfaces, while the field lines are parallel to the long axes of the wires, leading to more significant flux penetration in the coated regions. This facilitates a uniform low-loss current flow in the uncoated regions of the wires. In contrast, coating with a non-magnetic material gives rise to a considerably smaller current flow in the uncoated regions, whereas the low-loss flow is maintained in the coated regions. Moreover, the current flows in opposite directions in the coated and uncoated regions, where the direction in each region is converse for the two materials.展开更多
The anchoring property of the substrate surface of liquid crystal cells plays an important role in display and nondisplay fields. This property directly affects the deformation of liquid crystal molecules to change th...The anchoring property of the substrate surface of liquid crystal cells plays an important role in display and nondisplay fields. This property directly affects the deformation of liquid crystal molecules to change the phase difference through liquid crystal cells. In this paper, a test method based on the alternating-current bridge is proposed to determine the capacitance of liquid crystal cells and thus measure the anchoring energy of the substrate surface. The anchoring energy can be obtained by comparing the capacitance-voltage curves of twisted nematic liquid crystal cells with different anchoring properties in experimental and theoretical results simulated on the basis of Frank elastic theory. Compared with the other methods to determine the anchoring energy, our proposed method requires a simple treatment of liquid crystal cells and allows easy and high-accuracy measurements, thereby expanding the test ideas on the performance parameters of liquid crystal devices.展开更多
A rapid, simple and sensitive method was demonstrated for the determination of phenolic compounds in water samples by alternating-current oscillopolarographic titration. With the presence of sulfuric acid, phenol coul...A rapid, simple and sensitive method was demonstrated for the determination of phenolic compounds in water samples by alternating-current oscillopolarographic titration. With the presence of sulfuric acid, phenol could be transferred into a nitroso-compound by reacting with NaNO2. The titration end-point was obtained by the formation of a sharp cut in the oscillopolarographic with infinitesimal NaNO2 on double platinum electrodes. The results showed that phenol had an excellent linear relationship over the range of 4.82×10^-6 -9.65×10^-3 mol/L, the RSD of the proposed method was lower than 1.5%, and the spiked recoveries of three real water samples were in the range of 95.6%-106.9%.展开更多
In this article, an organic thin-film field-effect transistor （OTFFET） with top-gate and bottom-contact geometry based on pentacene as the active layer is fabricated. The experimental data of the I-V are obtained fr...In this article, an organic thin-film field-effect transistor （OTFFET） with top-gate and bottom-contact geometry based on pentacene as the active layer is fabricated. The experimental data of the I-V are obtained from the OTFFET device. The alternating-current （AC） resistance value of the OTFFET device is calculated using the derivation method from the experimental data, and the AC resistance trend curves of the OTFFET device are obtained with the region fitting method. We analyse the characteristics of the OTFFET device with an AC resistance trend curve. To discover whether it has a high resistance, it is proposed to judge the region of the source/drain voltage （VDs） less than the transition voltage, thereby determining whether the contact between the metal electrode and the organic semiconductor layer of the OTFFET device is Ohmic or non-Ohmic. The theoretical analysis shows that the field-effect mobility and the AC resistance are in reverse proportion. Therefore, we point out that reducing AC resistance is necessary if field-effect mobility is to be improved.展开更多
A new dimmer using a mental-oxide-semiconductor field-effect transistor (MOSFET) for alternating-current (AC) directly driven light-emitting-diode (LED) lamp was presented. The control method of proposed dimmer is pul...A new dimmer using a mental-oxide-semiconductor field-effect transistor (MOSFET) for alternating-current (AC) directly driven light-emitting-diode (LED) lamp was presented. The control method of proposed dimmer is pulse width control (PWM) method. Compared with the conventional phase-controlled dimmer, the proposed PWM dimmer can produce sine wave and did not cause harmonics problem. Furthermore, the proposed control method did not amplify the light flicker due to the independence of input voltage. Therefore, the PWM dimmer can be used as the dimmer of the AC LED lamp instead of the conventional phase-controlled dimmer. The experimental result shows that the proposed PWM dimmer has good performances.展开更多
In order to achieve the target of reducing oil consumption to zero for pulverized coal(PC)boiler in power plant,the paper developed a novel coal pulverized ignition approach,called as Alternating-Current plasma(AC pla...In order to achieve the target of reducing oil consumption to zero for pulverized coal(PC)boiler in power plant,the paper developed a novel coal pulverized ignition approach,called as Alternating-Current plasma(AC plasma)ignition,with the advantages of excellent PC combustion behavior and longer electrode life-span.The scientific principle of how to generate the AC plasma arc was elaborated in detail.First,the experiments on life-span of electrodes inside AC plasma generator had been conducted,finding a workable way to extend its life-span beyond 530 hours.Second,a new AC plasma burner specifically designed for lean coal according to the principle of PC staged combustion had been illustrated with diagrams and then used to ignite the PC-air stream under four kinds of conditions with a varying AC plasma power from 150 kW to 300 kW,focusing on analyses of the influence of AC plasma power on combustion behaver,such as combustion temperature,carbon burnout rate as well as PC combustion regime.The following results showed that in the case of the power of the AC plasma was P=300 kW,a satisfied PC combustion process could achieved,with the average PC combustion temperature of about 940°C,combustion flame length of 6.3 m,and the total carbon burnout rate of up to 52.2%.In addition,about 80%of the nozzle outlet section was filled with bright flame,while 81%of the PC was in zone of the cylindrical flame regime.The PC combustion modes were changed repeatedly during the process of combustion,which went from homogeneous combustion mode at initial ignition stage to combined combustion mode and heterogeneous combustion mode at middle stage,finally to combined combustion mode at later stage.The research conclusion in this paper has proved that the AC plasma ignition approach is feasible and effective to ignite low-rank coal without the present of fuel oil.展开更多
基金Foundation of China(grant nos.21621001,21920102005,21835002,and 21671075)the 111 Project of China(B17020)the financial supports.
文摘Organic afterglow materials are highly desirable for optoelectronic applications,but they usually suffer from complex preparation process,low quantum efficiency,and short lifetime due to the ultrafast deactivation of the highly active excited states involved.Here,we succeeded in achieving solventfree thermal syntheses of high-efficiency afterglow CDs@zeolite composite materials by simply grinding the solid raw materials of zeolite and precursor CDs at room temperature,followed by thermal crystallization.This method afforded maximum embedding of CDs into growing zeolite crystals,as well as strong host–guest interaction to surpass the nonradiative transition of CDs,thus producing composite materials with ultralong dual emission of thermally activated delayed fluorescence and room temperature phosphorescence with a record high lifetime of 1.7 and 2.1 s,respectively,and the quantum yield of 90.7%.Furthermore,in a preliminary experiment,we applied the composite materials in alternatingcurrent light-emitting diode supplementary lighting,which exhibited a promising potential in optoelectronic applications.
文摘A new method for the determination of aniline in environmental water based on oscillopolarographic titration was presented in this paper. Several factors including the kind, concentration, and volume of acid, the dosage of potassium bromide, the temperature and concentration of concomitant substances were investigated in detail. The experimental results indicated that this method was simple, rapid, and sensitive. The linear range was 8.367 × 10(?4) to 2.789 × 10(?2) mol L(?1), the relative standard deviation (R.S.D.) was lower than 0.96%, and the spiked recoveries of aniline in environmental water samples were in the range of 99.4–106.9% under the optimal conditions. The results indicated that the present method could be used as an alternative method for aniline determination in realworld water samples.
基金supported by National Natural Science Foundation of China(No.52177130)the Key Projects for Industrial Prospects and Core Technology Research in Suzhou City(No.SYC2022029)。
文摘Dielectric barrier discharge(DBD)plasma excited by a high-frequency alternating-current(AC)power supply is widely employed for the degradation of volatile organic compounds(VOCs).However,the thermal effect generated during the discharge process leads to energy waste and low energy utilization efficiency.In this work,an innovative DBD thermally-conducted catalysis(DBD-TCC)system,integrating high-frequency AC-DBD plasma and its generated thermal effects to activate the Co/SBA-15 catalyst,was employed for toluene removal.Specifically,Co/SBA-15 catalysts are closely positioned to the ground electrode of the plasma zone and can be heated and activated by the thermal effect when the voltage exceeds 10 k V.At12.4 k V,the temperature in the catalyst zone reached 261℃ in the DBD-TCC system,resulting in an increase in toluene degradation efficiency of 17%,CO_(2)selectivity of 21.2%,and energy efficiency of 27%,respectively,compared to the DBD system alone.In contrast,the DBD thermally-unconducted catalysis(DBD-TUC)system fails to enhance toluene degradation due to insufficient heat absorption and catalytic activation,highlighting the crucial role of AC-DBD generated heat in the activation of the catalyst.Furthermore,the degradation pathway and mechanism of toluene in the DBD-TCC system were hypothesized.This work is expected to provide an energy-efficient approach for high-frequency AC-DBD plasma removal of VOCs.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.40876094 and JQ10974106)the National High Technology Research and Development Program of China(Grant Nos.2009AA09Z102 and 2008AA09A403)+1 种基金the Excellent Youth Fundation of Shandong Scientific Committee,China(Grant No.JQ201018)the Natural Science Foundation of Shandong Province,China(Grant No.ZR2009AZ002)
文摘The perturbation method is used to study the localization of electric field distribution and the effective nonlinear response of graded composites under an external alternating-current（AC） and direct-current（DC） electric field E app = E 0（1 ＋ sin ωt）.The dielectric profile of the cylindrical inclusions is modeled by function ε i（r） = C k r k（r ≤ a）,where r is the radius of the cylindrical inclusion,and C k,k,a are parameters.In the dilute limit,the local potentials and the effective nonlinear responses at all harmonics are derived.Meanwhile,the general effective nonlinear responses are also derived and compared with the effective nonlinear responses at harmonics under the AC and DC external field.It is found that the effective nonlinear AC and DC responses at harmonics can be calculated by those of the general effective nonlinear of the graded composites under the external DC electric field.Moreover,the obtained local electrical fields show that the electrical field distribution in the cylindrical inclusions is controllable,and the maximum of the electric field inside the cylinder is at its center.
基金Project supported by the Fund from the Scientific and Technological Research Council of Turkey(TüB˙ITAK)(Grant No.110T876)
文摘Alternating-current losses in a two-layer superconducting cable, each layer being composed of 15 closely-spaced rectangular wires made up of second-generation superconductors when the ends of wires are coated by either a non-magnetic or strong ferromagnetic material having a U profile is numerically investigated. Computations are carried out through the finite-element method. The alternating-current losses do not increase significantly if the relative permeability of the coating is increased three orders of magnitude, provided that the current amplitude is less than half of the critical current in a superconducting wire. However, the losses are much higher for ferromagnetic coating if the amplitude of the applied current oscillating at 50 Hz is close to the critical current. The ferromagnetic coating is seen to accumulate the magnetic field lines normally on its surfaces, while the field lines are parallel to the long axes of the wires, leading to more significant flux penetration in the coated regions. This facilitates a uniform low-loss current flow in the uncoated regions of the wires. In contrast, coating with a non-magnetic material gives rise to a considerably smaller current flow in the uncoated regions, whereas the low-loss flow is maintained in the coated regions. Moreover, the current flows in opposite directions in the coated and uncoated regions, where the direction in each region is converse for the two materials.
基金supported by the National Natural Science Foundation of China(Grant Nos.11374087 and 11504080)the Natural Science Foundation of Hebei Province,China(Grant Nos.A2014202123 and A2017202004)+2 种基金the Research Project of the Education Department of Hebei Province,China(Grant No.QN2014130)the Key Subject Construction Project of Hebei Provincial Universitythe Undergraduate Innovation and Entrepreneurship Training Program,China(Grant No.201610080016)
文摘The anchoring property of the substrate surface of liquid crystal cells plays an important role in display and nondisplay fields. This property directly affects the deformation of liquid crystal molecules to change the phase difference through liquid crystal cells. In this paper, a test method based on the alternating-current bridge is proposed to determine the capacitance of liquid crystal cells and thus measure the anchoring energy of the substrate surface. The anchoring energy can be obtained by comparing the capacitance-voltage curves of twisted nematic liquid crystal cells with different anchoring properties in experimental and theoretical results simulated on the basis of Frank elastic theory. Compared with the other methods to determine the anchoring energy, our proposed method requires a simple treatment of liquid crystal cells and allows easy and high-accuracy measurements, thereby expanding the test ideas on the performance parameters of liquid crystal devices.
基金Project supported by the Creative Talented Person's Fund of Henan Province (High Teaching [2005]-126)the Natural Science Foundation of Henan Province (No. 0511053000)+1 种基金the Youth Science Foundation of Henan Normal University (No. 2004005)the Henan Key Laboratory for Environmental Pollution Control.
文摘A rapid, simple and sensitive method was demonstrated for the determination of phenolic compounds in water samples by alternating-current oscillopolarographic titration. With the presence of sulfuric acid, phenol could be transferred into a nitroso-compound by reacting with NaNO2. The titration end-point was obtained by the formation of a sharp cut in the oscillopolarographic with infinitesimal NaNO2 on double platinum electrodes. The results showed that phenol had an excellent linear relationship over the range of 4.82×10^-6 -9.65×10^-3 mol/L, the RSD of the proposed method was lower than 1.5%, and the spiked recoveries of three real water samples were in the range of 95.6%-106.9%.
基金Project supported by the National Grand Fundamental Research 973 Program of China (Grant No. 2010CB327704)the National Natural Science Foundation of China (Grant Nos. 10974013 and 60978060)+3 种基金the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20090009110027)the Natural Science Foundation of Beijing,China (Grant No. 1102028)the National Natural Science Foundation for Distinguished Young Scholars (Grant No. 60825407)Beijing Municipal Science and Technology Commission (Grant No. Z090803044009001)
文摘In this article, an organic thin-film field-effect transistor （OTFFET） with top-gate and bottom-contact geometry based on pentacene as the active layer is fabricated. The experimental data of the I-V are obtained from the OTFFET device. The alternating-current （AC） resistance value of the OTFFET device is calculated using the derivation method from the experimental data, and the AC resistance trend curves of the OTFFET device are obtained with the region fitting method. We analyse the characteristics of the OTFFET device with an AC resistance trend curve. To discover whether it has a high resistance, it is proposed to judge the region of the source/drain voltage （VDs） less than the transition voltage, thereby determining whether the contact between the metal electrode and the organic semiconductor layer of the OTFFET device is Ohmic or non-Ohmic. The theoretical analysis shows that the field-effect mobility and the AC resistance are in reverse proportion. Therefore, we point out that reducing AC resistance is necessary if field-effect mobility is to be improved.
文摘A new dimmer using a mental-oxide-semiconductor field-effect transistor (MOSFET) for alternating-current (AC) directly driven light-emitting-diode (LED) lamp was presented. The control method of proposed dimmer is pulse width control (PWM) method. Compared with the conventional phase-controlled dimmer, the proposed PWM dimmer can produce sine wave and did not cause harmonics problem. Furthermore, the proposed control method did not amplify the light flicker due to the independence of input voltage. Therefore, the PWM dimmer can be used as the dimmer of the AC LED lamp instead of the conventional phase-controlled dimmer. The experimental result shows that the proposed PWM dimmer has good performances.
基金supported by the national natural science foundation of china(Contract No.51806132)doctor start-up capital of Shanxi University(No.20174462)。
文摘In order to achieve the target of reducing oil consumption to zero for pulverized coal(PC)boiler in power plant,the paper developed a novel coal pulverized ignition approach,called as Alternating-Current plasma(AC plasma)ignition,with the advantages of excellent PC combustion behavior and longer electrode life-span.The scientific principle of how to generate the AC plasma arc was elaborated in detail.First,the experiments on life-span of electrodes inside AC plasma generator had been conducted,finding a workable way to extend its life-span beyond 530 hours.Second,a new AC plasma burner specifically designed for lean coal according to the principle of PC staged combustion had been illustrated with diagrams and then used to ignite the PC-air stream under four kinds of conditions with a varying AC plasma power from 150 kW to 300 kW,focusing on analyses of the influence of AC plasma power on combustion behaver,such as combustion temperature,carbon burnout rate as well as PC combustion regime.The following results showed that in the case of the power of the AC plasma was P=300 kW,a satisfied PC combustion process could achieved,with the average PC combustion temperature of about 940°C,combustion flame length of 6.3 m,and the total carbon burnout rate of up to 52.2%.In addition,about 80%of the nozzle outlet section was filled with bright flame,while 81%of the PC was in zone of the cylindrical flame regime.The PC combustion modes were changed repeatedly during the process of combustion,which went from homogeneous combustion mode at initial ignition stage to combined combustion mode and heterogeneous combustion mode at middle stage,finally to combined combustion mode at later stage.The research conclusion in this paper has proved that the AC plasma ignition approach is feasible and effective to ignite low-rank coal without the present of fuel oil.
