Due to a series of challenges such as low-orbit maintenance of satellites, the air-breathing electric propulsion has got widespread attention. Commonly, the radio frequency ion thruster is favored by low-orbit mission...Due to a series of challenges such as low-orbit maintenance of satellites, the air-breathing electric propulsion has got widespread attention. Commonly, the radio frequency ion thruster is favored by low-orbit missions due to its high specific impulse and efficiency. In this paper, the power transfer efficiency of the radio frequency ion thruster with different gas compositions is studied experimentally, which is obtained by measuring the radio frequency power and current of the antenna coil with and without discharge operation. The results show that increasing the turns of antenna coils can effectively improve the radio frequency power transfer efficiency, which is due to the improvement of Q factor. In pure N_2 discharge,with the increase of radio frequency power, the radio frequency power transfer efficiency first rises rapidly and then exhibits a less steep increasing trend. The radio frequency power transfer efficiency increases with the increase of gas pressure at relatively high power, while declines rapidly at relatively low power. In N_(2)/O_(2) discharge, increasing the N_(2) content at high power can improve the radio frequency power transfer efficiency, but the opposite was observed at low power. In order to give a better understanding of these trends, an analytic solution in limit cases is utilized, and a Langmuir probe was employed to measure the electron density. It is found that the evolution of radio frequency power transfer efficiency can be well explained by the variation of plasma resistance, which is related to the electron density and the effective electron collision frequency.展开更多
The charge transfer efficiency improvement method is introduced by optimizing the electrical potential distribution under the transfer gate along the charge transfer path. A non-uniform doped transfer transistor chan-...The charge transfer efficiency improvement method is introduced by optimizing the electrical potential distribution under the transfer gate along the charge transfer path. A non-uniform doped transfer transistor chan- nel is introduced to provide an ascending electrical potential gradient in the transfer transistor channel. With the adjustments to the overlap length between the R1 region and the transfer gate, the doping dose of the R1 region, and the overlap length between the anti-punch-through (APT) implantations and transfer gate, the potential barrier and potential pocket in the connecting region of transfer transistor channel and the pinned photodiode (PPD) are reduced to improve the electrical potential connection. The simulation results show that the percentage of residual charges to total charges drops from 1/10^4 to 1/10^7, and the transfer time is reduced from 500 to 110 ns. This means the charge transfer efficiency is improved.展开更多
A novel CMOS image sensor(CIS) pinned photodiode(PPD) pixel, named as O-T pixel, is proposed and investigated by TCAD simulations. Compared with the conventional PPD pixel, the proposed pixel features the overlapping ...A novel CMOS image sensor(CIS) pinned photodiode(PPD) pixel, named as O-T pixel, is proposed and investigated by TCAD simulations. Compared with the conventional PPD pixel, the proposed pixel features the overlapping gate(OG)and the temporary storage diffusing(TSD) region, based on which the several-nanosecond-level charge transfer could be achieved and the complete charge transfer from the PPD to the floating node(FD) could be realized. And systematic analyses of the influence of the doping conditions of the proposed processes, the OG length, and the photodiode length on the transfer performances of the proposed pixel are conducted. Optimized simulation results show that the total charge transfer time could reach about 5.862 ns from the photodiode to the sensed node and the corresponding charge transfer efficiency could reach as high as 99.995% in the proposed pixel with 10 μm long photodiode and 2.22 μm long OG. These results demonstrate a great potential of the proposed pixel in high-speed applications.展开更多
Combined with two-dimensional(2D)and three-dimensional(3D)finite element analysis and preliminary experimental tests,the effects of size and placement of the electromagnetic shield of the radio-frequency(RF)ion source...Combined with two-dimensional(2D)and three-dimensional(3D)finite element analysis and preliminary experimental tests,the effects of size and placement of the electromagnetic shield of the radio-frequency(RF)ion source with two drivers on plasma parameters and RF power transfer efficiency are analyzed.It is found that the same input direction of the current is better for the RF ion source with multiple drivers.The electromagnetic shield(EMS)should be placed symmetrically around the drivers,which is beneficial for the plasma to distribute uniformly and symmetrically in both drivers.Furthermore,the bigger the EMS shield radius is the better generating a higher electron density.These results will be of guiding significance to the design of electromagnetic shielding for RF ion sources with a multi-driver.展开更多
The flux-variance similarity relation and the vertical transfer of scalars exhibit dissimilarity over different types of surfaces, resulting in different parameterization approaches of relative transport efficiency am...The flux-variance similarity relation and the vertical transfer of scalars exhibit dissimilarity over different types of surfaces, resulting in different parameterization approaches of relative transport efficiency among scalars to estimate turbulent fluxes using the flux-variance method. We investigated these issues using eddycovariance measurements over an open, homogeneous and flat grassland in the eastern Tibetan Plateau in summer under intermediate hydrological conditions during rainy season. In unstable conditions, the temperature, water vapor, and CO2 followed the flux-variance similarity relation, but did not show in precisely the same way due to different roles (active or passive) of these scalars. Similarity constants of temperature, water vapor and CO2 were found to be 1.12, 1.19 and 1.17, respectively. Heat transportation was more eft% cient than water vapor and CO2. Based on the estimated sensible heat flux, five parameterization methods of relative transport efficiency of heat to water vapor and CO2 were examined to estimate latent heat and CO2 fluxes. The strategy of local determination of flux-variance similarity relation is recommended for the estimation of latent heat and CO2 fluxes. This approach is better for representing the averaged relative transport efficiency, and technically easier to apply, compared to other more complex ones.展开更多
Electron donors(EDs)are widely used to improve the H 2 production performance of Schottky junction photocatalysts,but the functions of EDs are still unknown from the perspective of electron transfer dy-namics.Herein,P...Electron donors(EDs)are widely used to improve the H 2 production performance of Schottky junction photocatalysts,but the functions of EDs are still unknown from the perspective of electron transfer dy-namics.Herein,Pt nanocluster-decorated CdS nanorod is successfully prepared to construct a typical CdS/Pt Schottky junction.Pt nanoclusters with a diameter of∼2 nm are deposited on the surface of CdS nanorods by in situ photoreduction at sub-zero temperature.The CdS/Pt photocatalyst using lactic acid shows a higher H_(2)production rate of 4762μmol g^(-1)h^(-1)compared to that using methanol,tri-ethanolamine,and glycerol.To understand the cause,the dynamics of photogenerated carriers in CdS/Pt photocatalysts during ED-assisted H_(2)production are revealed by femtosecond transient absorption spec-troscopy.Among the four organic EDs,lactic acid enables the fastest electron transfer rate of 1.8×10^(9)s^(-1)and the highest electron transfer efficiency of 76%at the CdS/Pt interface due to the most efficient hole consumption.This work sheds light on the importance of efficient interfacial electron transfer for im-proving the photocatalytic performance of Schottky junction photocatalysts.展开更多
A preliminary design for a heavy ion driver inertial fusion(HIDIF) target is presented. The effect of target material and dimensions on transfer efficiency and symmetrical irradiation in the hohlraum are investigate...A preliminary design for a heavy ion driver inertial fusion(HIDIF) target is presented. The effect of target material and dimensions on transfer efficiency and symmetrical irradiation in the hohlraum are investigated.The analysis led to the evaluation of optimal target materials and dimensions to achieve a positive power balance of an ICF power plant.The results show that the best choice is a high Z material for cavity wall materials and a low Z material for the capsule ablator.It is concluded that for achieving the highest transfer efficiency and best symmetrization we need an area ratio between 5≤A2/A1≤9.展开更多
Three laboratory-scale moving bed biofilm reactors (MBBR) with different carrier filling ratios ranging from 40% to 60% were used to study the effects of carrier-attached biofilm on oxygen transfer efficiency. In th...Three laboratory-scale moving bed biofilm reactors (MBBR) with different carrier filling ratios ranging from 40% to 60% were used to study the effects of carrier-attached biofilm on oxygen transfer efficiency. In this study, we evaluated the performance of three MBBRs in degrading chemical oxygen demand and ammonia. The three reactors removed more than 95% of NH4^+ -N at an air flow-rate of 60L·h^-1. The standard oxygen transfer efficiency (αSOTE) of the three reactors was also investigated at air flow-rates ranging from 60 to 100L·h^-1. These results were compared to αSOTE of wastewater with a clean carrier (no biofilm attached). Results showed that under. these process conditions, αSOTE decreased by approximately 70% as compared to αSOTE of wastewater at a different carrier-filling ratio. This indicated that the biofilm attached to the cartier had a negative effect on αSOTE. Mechanism analysis showed that the main inhibiting effects were related to biofilm flocculants and soluble microbial product (SMP). Biofilm flocs could decrease otSOTE by about 20%, and SMP could decrease aαSOTE by 30%--50%.展开更多
The food system is one of the major sources of anthropogenic greenhouse gas(GHG)emissions.The impact of emission transfer due to the separation between food production and consumption within the context of carbon neut...The food system is one of the major sources of anthropogenic greenhouse gas(GHG)emissions.The impact of emission transfer due to the separation between food production and consumption within the context of carbon neutrality remains unclear.In this study,we constructed an emission inventory for three types of grains at the production stage of their life cycle and then analysed the spatiotemporal evolution characteristics of the grain supply and demand.With the use of a spatial equilibrium model,we simulated the spatial distribution flow of the different types of grains from 1990 to 2018 and calculated the resulting GHG emission transfer efficiency.The main results include the following:(1)The imbalance between the grain supply and demand intensified,which was mainly reflected in the distance between the geographic centre of the grain supply and consumption increasing 3.2 times,and thus,the self-sufficiency decreased.(2)The total emission transfer TET of rice and wheat decreased because of the increase in the intra-regional supply,while that of maize gradually increased due to the increase in the inter-regional supply.(3)Overall,grain trade improved the carbon efficiency of grain production in China.The trade efficiency of crops varied,with wheat and maize leading to overall effective carbon reductions,while the carbon transfer efficiency of rice from trade was relatively low.(4)The carbon footprint of grain production in China's provinces exhibited a downward trend,but due to the intensified separation between the grain supply and demand,certain major grain-producing areas achieved inefficient carbon increases.Therefore,we suggest further optimization of the spatial structure of planting and breeding,strengthening of the grain supply in the region,and enhancement in the optimization of the low-carbon production structure and adjustment of cultivated land use combined with regional governance strategies.The application of these measures could contribute to achieving dual-carbon goals.展开更多
In mammalians, the state of a somatic cell can be reversed from the terminal state to the totipotent state by means of somatic cell nuclear transfer (SCNT) (Gurdon, 1962) or induced pluripotent stem cells (iPSCs...In mammalians, the state of a somatic cell can be reversed from the terminal state to the totipotent state by means of somatic cell nuclear transfer (SCNT) (Gurdon, 1962) or induced pluripotent stem cells (iPSCs) (Takahashi and Yamanaka, 2006). The DNA methylation and transcriptome profiles of embryonic stern cells (ESCs) derived from SCNT embryos (NT-ESCs) correspond closely to those of ESCs derived from in vitro fertilization embryos (IVF- ESCs). In contrast, iPSCs differ from both NT-ESCs and IVF-ESCs in that they retain the residual DNA methylation patterns of their parental somatic cells. As SCNT can be used to faithfully reprogram human somatic cells to pluripotency, it is ideal for cell replacement therapies (Ma et al., 2014). Following the successful production of the first human NT-ESCs (Tachibana et al., 2013) and the later gen- eration of human NT-ESCs based on cells from elderly adults or pa- tient cells (Chung et al., 2014; Yamada et al., 2014), a version of the SCNT technique for human therapeutics comes closer to reality. However, no matter what animal species or donor cell types are used in the cloned process, the cloning efficiency remains undesir- able. Besides, there are many phenotypic abnormalities in cloned animals, containing frequent embryonic and perinatal death and placentomegaly, and the underlying mechanisms remain unclear (Yang et al, 2007).展开更多
The internal quantum efficiency(IQE) of the light-emitting diodes can be calculated by the ratio of the external quantum efficiency(EQE) and the light extraction efficiency(LEE).The EQE can be measured experimen...The internal quantum efficiency(IQE) of the light-emitting diodes can be calculated by the ratio of the external quantum efficiency(EQE) and the light extraction efficiency(LEE).The EQE can be measured experimentally,but the LEE is difficult to calculate due to the complicated LED structures.In this work,a model was established to calculate the LEE by combining the transfer matrix formalism and an in-plane ray tracing method.With the calculated LEE,the IQE was determined and made a good agreement with that obtained by the ABC model and temperature-dependent photoluminescence method.The proposed method makes the determination of the IQE more practical and conventional.展开更多
We develop a new kind of underwater inductive coupling power transfer(ICPT)system to evaluate wireless power transfer in autonomous underwater vehicle(AUV)docking applications.Parameters that determine the performance...We develop a new kind of underwater inductive coupling power transfer(ICPT)system to evaluate wireless power transfer in autonomous underwater vehicle(AUV)docking applications.Parameters that determine the performance of the system are systematically analyzed through mathematical methods.A circuit simulation model and a finite element analysis(FEA)simulation model are developed to study the power losses of the system,including copper loss in coils,semiconductor loss in circuits,and eddy current loss in transmission media.The characteristics of the power losses can provide guidelines to improve the efficiency of ICPT systems.Calculation results and simulation results are validated by relevant experiments of the prototype system.The output power of the prototype system is up to 45 W and the efficiency is up to 0.84.The preliminary results indicate that the efficiency will increase as the transmission power is raised by increasing the input voltage.When the output power reaches 500 W,the efficiency is expected to exceed 0.94.The efficiency can be further improved by choosing proper semiconductors and coils.The analysis methods prove effective in predicting the performance of similar ICPT systems and should be useful in designing new systems.展开更多
Nanopowder of Cr:GGG and nanopowder of Cr,Nd:GGG with different concentrations of Cr3+ ranging from 0.1 at.% to 1.5 at.% were synthesized by the sol-gel method using acetic acid and ethylene glycol. Thermal gravime...Nanopowder of Cr:GGG and nanopowder of Cr,Nd:GGG with different concentrations of Cr3+ ranging from 0.1 at.% to 1.5 at.% were synthesized by the sol-gel method using acetic acid and ethylene glycol. Thermal gravimetric analysis and differential scanning calorimetry (TGA-DSC), X-ray diffraction (XRD) and photoluminescence spectroscopy were used to characterize the powder. The crystallite size was about 58 nm when treated at 1000 oC for 2 h. Cr3+ photoluminescence spectrum in GGG showed a broad band emission around 730 nm. The intensity of this band decreased when co-doped with Nd, indicating an efficient energy transfer from Cr3+ to Nd3+. Photoluminescence intensity of Nd in Cr,Nd:GGG at 1.06μm showed that the optimum concentration of Cr3+ was about 1 at.% (more or less) for 1 at.% Nd3+. This result was also confirmed by chromium fluorescence decay rate analysis. Energy transfer efficiency was found to be about 84% for 1 at.% concentration of each chromium and neodymium.展开更多
A 1-dodecanethiol-based phase-transfer protocol is developed for the extraction of noble metal ions from aqueous solution to a hydrocarbon phase, which calls for first mixing the aqueous metal ion solution with an eth...A 1-dodecanethiol-based phase-transfer protocol is developed for the extraction of noble metal ions from aqueous solution to a hydrocarbon phase, which calls for first mixing the aqueous metal ion solution with an ethanolic solution of 1-dodecanethiol, and then extracting the coordination compounds formed between noble metal ions and 1-dodecanethiol into a non-polar organic solvent. A number of characterization techniques, including inductively coupled plasma atomic emission spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis demonstrate that this protocol could be applied to extract a wide variety of noble metal ions from water to dichlorometh- ane with an efficiency of 〉96%, and has high selectivity for the separation of the noble metal ions from other transition metals. It is therefore an attractive alternative for the extraction of noble metals from water, soil, or waste printed circuit boards.展开更多
This work provides an approach to determine the efficiency of T-ray detectors with a good accuracy in order to determine the concentrations of either naturally occurring or artificially prepared radionuclides. This ap...This work provides an approach to determine the efficiency of T-ray detectors with a good accuracy in order to determine the concentrations of either naturally occurring or artificially prepared radionuclides. This approach is based on the efficiency transfer formula (ET), the effective solid angles, the self- absorptions of the source matrix, the attenuation by the source container and the detector housing materials on the detector efficiency. The experimental calibration process was done using radioactive (Cylindrical & Marinelli) sources, in different dimensions, that contain aqueous 152Eu radionuclide. The comparison point to a fine agreement between the experimental measured and calculated efficiencies for the (NaI & HPGe) detectors using volumetric radioactive sources.展开更多
Porous solid scaffolds play key roles in preventing nanocatalysts from agglomeration,greatly maintaining the catalytic efficiency and stability of nanocatalysts.However,facile preparation of robust scaffolds with high...Porous solid scaffolds play key roles in preventing nanocatalysts from agglomeration,greatly maintaining the catalytic efficiency and stability of nanocatalysts.However,facile preparation of robust scaffolds with high mass transfer efficiency for loading nanocatalysts remains a major challenge.Here,we fabricate a wood-inspired shape-memory chitosan scaffold for loading Au nanoparticles to reduce 4-nitrophenol via a simple“freeze-casting and dip-adsorption”approach.The obtained catalytic scaffold highly resembles the unidirectional microchannel structure of natural wood,resulting in robust mechanical properties and outstanding water absorption capacity.Additionally,Au nanoparticles can be firmly and uniformly anchored on the inner surface of these microchannels via electrostatic interaction,forming numerous microreactors.This catalytic system exhibits a high 4-nitrophenol conversion rate of 99%in 5 s and impressive catalytic stability even after continuously treating with more than 3 L of highly concentrated 4-nitrophenol solution(1 mmol/L).Therefore,the wood-like catalytic system presented here demonstrates the potential to be applied in the field of water treatment and environmental protection.展开更多
Deeply photocatalytic oxidation of NO-to-NO_(3)holds great promise for alleviating NO_(x) pollution.The major challenge of NO photo-oxidation is the highly in-situ generated NO_(2) concentration,and the formation of u...Deeply photocatalytic oxidation of NO-to-NO_(3)holds great promise for alleviating NO_(x) pollution.The major challenge of NO photo-oxidation is the highly in-situ generated NO_(2) concentration,and the formation of unstable nitrate species causes desorption to release NO_(2).In this study,SnO_(2) quantum dots and oxygen vacancies co-modified Zn_(2)SnO_(4)(ZSO-SnO_(2)-OVs)were prepared by a one-step hydrothermal procedure,the NO photo-oxidation was investigated by a combination of solid experimental and theoretical support.Impressively,spectroscopic measurements indicate that fast carrier dynamics can be achieved due to the electron transfer efficiency of ZSO-SnO_(2)-OVs reaching 99.99%,far outperforming the counterpart and previously reported photocatalysts.During NO oxidation,molecular NO/O_(2) and H2O are efficiently adsorbed/activated around OVs and SnO_(2) QDs,respectively.In-situ infrared measurements and calculated electron localized function disclose two main findings:(1)richly electrons enable NO promptly form NOinstead of toxic NO_(2) or NO^(+);(2)the generation of stable and undecomposed bidentate NO_(3)rather than bridging or monodentate one benefits the deep oxidation of NO via shifting reaction sites from O terminals for original ZSO to Sn ones for ZSO-SnO_(2)-OVs.The synergistic action of SnO_(2) QDs and OVs positively contributes to the NO oxidation performance enhancement(60.6%,0.1 g of sample)and high selectivity of NO to NO_(3)(99.2%).Results from this study advance the mechanistic understanding of NO photooxidation and its selectivity to NO_(3)over photocatalysts.展开更多
Fabrication of efficient solid luminogens with tunable emission is both fundamentally significant and technically important. Herein, based on our previous strategy for the construction of efficient and multifunctional...Fabrication of efficient solid luminogens with tunable emission is both fundamentally significant and technically important. Herein, based on our previous strategy for the construction of efficient and multifunctional solid luminogens through the combination of diverse aggregation-induced emission (ALE) units with other functional moieties, a group of luminophores with electron donor-acceptor (D-A) structure and typical intramolecular charge transfer (ICT) characteristics, namely CZ-DCDPP, DPA-DCDPP and DBPA-DCDPP were synthesized and investigated. The presence of twisting and AlE-active 2,3- dicyano-S,6-diphenylpyrazine (DCDPP) moiety endows them highly emissive in the solid states, whereas the introduction of arylamines with varied electron-donating capacity and different conjugation render them with tunable solid emissions from green to red. While CZ-DCDPP and DPA-DCDPP solids exhibit distinct mechanochromism, both DPA-DCDPP and DBPA-DCDPP solids can generate efficient red emission. Owing to their high efficiency, remarkable thermal and morphological stabilities and moreover red emission, they are promising for diverse optoelectronic and biological applications.展开更多
Powder coating is an important process in the food industry,especially for snack foods such as potato chips,to create variety in food products.Electrostatic coating has been adopted in order to provide better transfer...Powder coating is an important process in the food industry,especially for snack foods such as potato chips,to create variety in food products.Electrostatic coating has been adopted in order to provide better transfer efficiency and lower the dust produced during coating.Studying the effect of electrode voltage on coating efficiency and evenness of baked potato chips using the developed electrostatic powder coating system was the main purpose of this research.Different types of NaCl(refined and table salts)were coated on baked potato chips at 0,30,40,50,60,and 70 kV.After coating with either refined or table salt,transfer efficiency,adhesion after coating,coating evenness and texture of samples were determined.Higher transfer efficiency,adhesion and coating evenness were observed when electrostatic coating was conducted at 30-50 kV.Most samples with higher transfer efficiency,adhesion and evenness were obtained after electrostatic coating.However,it did not significantly affect hardness of baked potato chips.展开更多
Introduction THick Gas Electron Multiplier(THGEM)is considered in many UV photon detector applications.It has the capability of detecting single photon and imaging with high sensitivity.Operating parameters such as ch...Introduction THick Gas Electron Multiplier(THGEM)is considered in many UV photon detector applications.It has the capability of detecting single photon and imaging with high sensitivity.Operating parameters such as choice of gas mixture,pressure,drift field,drift gap,multiplication voltage,induction field and induction gap play an important role in deciding the spatial resolution of the detector.Detailed simulation study enables to optimize the above-mentioned parameters for a given THGEM-based imaging detector and hence to achieve improved performance for the same.Materials and methods Simulation,using ANSYS and Garfield++,starts with the release of primary electrons at random coordinates on the photocathode plane.They are tracked as they pass through the drift gap and THGEM hole till the electron cloud reaches anode plane.Distribution of electron cloud on the anode plane along X and Y axis is plotted in histogram and fitted with Gaussian function to determine spatial resolution.Ar/CO_(2)(70:30)mixture,which shows higher ETE and lower transverse diffusion,is chosen for this simulation study.Conclusion Transverse diffusion has a major impact on both ETE and the spatial resolution.Lower transverse diffusion coefficient is always desired for having better resolution as well as for ETE.It is found from the simulation study that higher gas pressure,lower drift field and induction field,smaller drift and induction gap can provide optimum detection efficiency with the best spatial resolution.The simulation method proposed here can also be extended to X-ray imaging detectors.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12005031 and 12275041)the Natural Science Fund from the Interdisciplinary Project of Dalian University(Grant No.DLUXK-2023-QN-001)。
文摘Due to a series of challenges such as low-orbit maintenance of satellites, the air-breathing electric propulsion has got widespread attention. Commonly, the radio frequency ion thruster is favored by low-orbit missions due to its high specific impulse and efficiency. In this paper, the power transfer efficiency of the radio frequency ion thruster with different gas compositions is studied experimentally, which is obtained by measuring the radio frequency power and current of the antenna coil with and without discharge operation. The results show that increasing the turns of antenna coils can effectively improve the radio frequency power transfer efficiency, which is due to the improvement of Q factor. In pure N_2 discharge,with the increase of radio frequency power, the radio frequency power transfer efficiency first rises rapidly and then exhibits a less steep increasing trend. The radio frequency power transfer efficiency increases with the increase of gas pressure at relatively high power, while declines rapidly at relatively low power. In N_(2)/O_(2) discharge, increasing the N_(2) content at high power can improve the radio frequency power transfer efficiency, but the opposite was observed at low power. In order to give a better understanding of these trends, an analytic solution in limit cases is utilized, and a Langmuir probe was employed to measure the electron density. It is found that the evolution of radio frequency power transfer efficiency can be well explained by the variation of plasma resistance, which is related to the electron density and the effective electron collision frequency.
基金Project supported by National Natural Science Foundation of China(Nos.61036004,61076024)
文摘The charge transfer efficiency improvement method is introduced by optimizing the electrical potential distribution under the transfer gate along the charge transfer path. A non-uniform doped transfer transistor chan- nel is introduced to provide an ascending electrical potential gradient in the transfer transistor channel. With the adjustments to the overlap length between the R1 region and the transfer gate, the doping dose of the R1 region, and the overlap length between the anti-punch-through (APT) implantations and transfer gate, the potential barrier and potential pocket in the connecting region of transfer transistor channel and the pinned photodiode (PPD) are reduced to improve the electrical potential connection. The simulation results show that the percentage of residual charges to total charges drops from 1/10^4 to 1/10^7, and the transfer time is reduced from 500 to 110 ns. This means the charge transfer efficiency is improved.
基金Project supported by the National Natural Science Foundation of China(Grant No.61574112)。
文摘A novel CMOS image sensor(CIS) pinned photodiode(PPD) pixel, named as O-T pixel, is proposed and investigated by TCAD simulations. Compared with the conventional PPD pixel, the proposed pixel features the overlapping gate(OG)and the temporary storage diffusing(TSD) region, based on which the several-nanosecond-level charge transfer could be achieved and the complete charge transfer from the PPD to the floating node(FD) could be realized. And systematic analyses of the influence of the doping conditions of the proposed processes, the OG length, and the photodiode length on the transfer performances of the proposed pixel are conducted. Optimized simulation results show that the total charge transfer time could reach about 5.862 ns from the photodiode to the sensed node and the corresponding charge transfer efficiency could reach as high as 99.995% in the proposed pixel with 10 μm long photodiode and 2.22 μm long OG. These results demonstrate a great potential of the proposed pixel in high-speed applications.
基金supported by the Comprehensive Research Facility for Fusion Technology Program of China(No.2018-000052-73-01-001228)National Natural Science Foundation of China(No.11975263)the National Key R&D Program of China(No.2017YFE0300101)。
文摘Combined with two-dimensional(2D)and three-dimensional(3D)finite element analysis and preliminary experimental tests,the effects of size and placement of the electromagnetic shield of the radio-frequency(RF)ion source with two drivers on plasma parameters and RF power transfer efficiency are analyzed.It is found that the same input direction of the current is better for the RF ion source with multiple drivers.The electromagnetic shield(EMS)should be placed symmetrically around the drivers,which is beneficial for the plasma to distribute uniformly and symmetrically in both drivers.Furthermore,the bigger the EMS shield radius is the better generating a higher electron density.These results will be of guiding significance to the design of electromagnetic shielding for RF ion sources with a multi-driver.
基金funding frown the Chinese National Key Programme for Developing Basic Sciences,the National Natural Science Foundation of China,the Key Program of the Chinese Academy of Sciences,the National Natural Science Foundation of China,the Foundation for Excellent Young Scholars of CAREERI
文摘The flux-variance similarity relation and the vertical transfer of scalars exhibit dissimilarity over different types of surfaces, resulting in different parameterization approaches of relative transport efficiency among scalars to estimate turbulent fluxes using the flux-variance method. We investigated these issues using eddycovariance measurements over an open, homogeneous and flat grassland in the eastern Tibetan Plateau in summer under intermediate hydrological conditions during rainy season. In unstable conditions, the temperature, water vapor, and CO2 followed the flux-variance similarity relation, but did not show in precisely the same way due to different roles (active or passive) of these scalars. Similarity constants of temperature, water vapor and CO2 were found to be 1.12, 1.19 and 1.17, respectively. Heat transportation was more eft% cient than water vapor and CO2. Based on the estimated sensible heat flux, five parameterization methods of relative transport efficiency of heat to water vapor and CO2 were examined to estimate latent heat and CO2 fluxes. The strategy of local determination of flux-variance similarity relation is recommended for the estimation of latent heat and CO2 fluxes. This approach is better for representing the averaged relative transport efficiency, and technically easier to apply, compared to other more complex ones.
基金the National Key Research and Development Program of China(Nos.2022YFB3803600 and 2018YFB1502001)National Natural Science Foundation of China(Nos.22238009,51932007,U1905215,52073223,52173065,and 52202375)+2 种基金the Natural Science Foundation of Hubei Province of China(No.2022CFA001)China Postdoctoral Science Foundation(Nos.2021TQ0311 and 2021M702990)International Postdoc-toral Exchange Fellowship Program(No.PC2022051).
文摘Electron donors(EDs)are widely used to improve the H 2 production performance of Schottky junction photocatalysts,but the functions of EDs are still unknown from the perspective of electron transfer dy-namics.Herein,Pt nanocluster-decorated CdS nanorod is successfully prepared to construct a typical CdS/Pt Schottky junction.Pt nanoclusters with a diameter of∼2 nm are deposited on the surface of CdS nanorods by in situ photoreduction at sub-zero temperature.The CdS/Pt photocatalyst using lactic acid shows a higher H_(2)production rate of 4762μmol g^(-1)h^(-1)compared to that using methanol,tri-ethanolamine,and glycerol.To understand the cause,the dynamics of photogenerated carriers in CdS/Pt photocatalysts during ED-assisted H_(2)production are revealed by femtosecond transient absorption spec-troscopy.Among the four organic EDs,lactic acid enables the fastest electron transfer rate of 1.8×10^(9)s^(-1)and the highest electron transfer efficiency of 76%at the CdS/Pt interface due to the most efficient hole consumption.This work sheds light on the importance of efficient interfacial electron transfer for im-proving the photocatalytic performance of Schottky junction photocatalysts.
文摘A preliminary design for a heavy ion driver inertial fusion(HIDIF) target is presented. The effect of target material and dimensions on transfer efficiency and symmetrical irradiation in the hohlraum are investigated.The analysis led to the evaluation of optimal target materials and dimensions to achieve a positive power balance of an ICF power plant.The results show that the best choice is a high Z material for cavity wall materials and a low Z material for the capsule ablator.It is concluded that for achieving the highest transfer efficiency and best symmetrization we need an area ratio between 5≤A2/A1≤9.
基金This study was supported by the National Natural Science Foundation of China (Grant No. 51408601).
文摘Three laboratory-scale moving bed biofilm reactors (MBBR) with different carrier filling ratios ranging from 40% to 60% were used to study the effects of carrier-attached biofilm on oxygen transfer efficiency. In this study, we evaluated the performance of three MBBRs in degrading chemical oxygen demand and ammonia. The three reactors removed more than 95% of NH4^+ -N at an air flow-rate of 60L·h^-1. The standard oxygen transfer efficiency (αSOTE) of the three reactors was also investigated at air flow-rates ranging from 60 to 100L·h^-1. These results were compared to αSOTE of wastewater with a clean carrier (no biofilm attached). Results showed that under. these process conditions, αSOTE decreased by approximately 70% as compared to αSOTE of wastewater at a different carrier-filling ratio. This indicated that the biofilm attached to the cartier had a negative effect on αSOTE. Mechanism analysis showed that the main inhibiting effects were related to biofilm flocculants and soluble microbial product (SMP). Biofilm flocs could decrease otSOTE by about 20%, and SMP could decrease aαSOTE by 30%--50%.
基金supported by the National Natural Science Foundation of China(Grant No.42201301)the Innovative Research Group Project of the National Natural Science Foundation of China(Grant No.71921003)the Special Fund of Jiangsu Province Carbon Peak and Carbon Neutral Technology Innovation(Grant No.BK2022037)。
文摘The food system is one of the major sources of anthropogenic greenhouse gas(GHG)emissions.The impact of emission transfer due to the separation between food production and consumption within the context of carbon neutrality remains unclear.In this study,we constructed an emission inventory for three types of grains at the production stage of their life cycle and then analysed the spatiotemporal evolution characteristics of the grain supply and demand.With the use of a spatial equilibrium model,we simulated the spatial distribution flow of the different types of grains from 1990 to 2018 and calculated the resulting GHG emission transfer efficiency.The main results include the following:(1)The imbalance between the grain supply and demand intensified,which was mainly reflected in the distance between the geographic centre of the grain supply and consumption increasing 3.2 times,and thus,the self-sufficiency decreased.(2)The total emission transfer TET of rice and wheat decreased because of the increase in the intra-regional supply,while that of maize gradually increased due to the increase in the inter-regional supply.(3)Overall,grain trade improved the carbon efficiency of grain production in China.The trade efficiency of crops varied,with wheat and maize leading to overall effective carbon reductions,while the carbon transfer efficiency of rice from trade was relatively low.(4)The carbon footprint of grain production in China's provinces exhibited a downward trend,but due to the intensified separation between the grain supply and demand,certain major grain-producing areas achieved inefficient carbon increases.Therefore,we suggest further optimization of the spatial structure of planting and breeding,strengthening of the grain supply in the region,and enhancement in the optimization of the low-carbon production structure and adjustment of cultivated land use combined with regional governance strategies.The application of these measures could contribute to achieving dual-carbon goals.
基金supported by grants from the National Natural Science Foundation of China(No.31471395)to Q.Z.the Key Research Projects of the Frontier Science of the Chinese Academy of Sciences(QYZDY-SSW-SMC002)to Q.Z
文摘In mammalians, the state of a somatic cell can be reversed from the terminal state to the totipotent state by means of somatic cell nuclear transfer (SCNT) (Gurdon, 1962) or induced pluripotent stem cells (iPSCs) (Takahashi and Yamanaka, 2006). The DNA methylation and transcriptome profiles of embryonic stern cells (ESCs) derived from SCNT embryos (NT-ESCs) correspond closely to those of ESCs derived from in vitro fertilization embryos (IVF- ESCs). In contrast, iPSCs differ from both NT-ESCs and IVF-ESCs in that they retain the residual DNA methylation patterns of their parental somatic cells. As SCNT can be used to faithfully reprogram human somatic cells to pluripotency, it is ideal for cell replacement therapies (Ma et al., 2014). Following the successful production of the first human NT-ESCs (Tachibana et al., 2013) and the later gen- eration of human NT-ESCs based on cells from elderly adults or pa- tient cells (Chung et al., 2014; Yamada et al., 2014), a version of the SCNT technique for human therapeutics comes closer to reality. However, no matter what animal species or donor cell types are used in the cloned process, the cloning efficiency remains undesir- able. Besides, there are many phenotypic abnormalities in cloned animals, containing frequent embryonic and perinatal death and placentomegaly, and the underlying mechanisms remain unclear (Yang et al, 2007).
基金supported by the National Natural Science Foundation of China(Nos.11574306,61334009)the China International Science and Technology Cooperation Program(No.2014DFG62280)the National High Technology Program of China(No.2015AA03A101)
文摘The internal quantum efficiency(IQE) of the light-emitting diodes can be calculated by the ratio of the external quantum efficiency(EQE) and the light extraction efficiency(LEE).The EQE can be measured experimentally,but the LEE is difficult to calculate due to the complicated LED structures.In this work,a model was established to calculate the LEE by combining the transfer matrix formalism and an in-plane ray tracing method.With the calculated LEE,the IQE was determined and made a good agreement with that obtained by the ABC model and temperature-dependent photoluminescence method.The proposed method makes the determination of the IQE more practical and conventional.
基金Project supported by the National High-Tech R&D Program of China(No.2013AA09A414)the National Natural Science Foundation of China(No.51221004)the Interdisciplinary Research Foundation of Zhejiang University(No.2012HY003A)
文摘We develop a new kind of underwater inductive coupling power transfer(ICPT)system to evaluate wireless power transfer in autonomous underwater vehicle(AUV)docking applications.Parameters that determine the performance of the system are systematically analyzed through mathematical methods.A circuit simulation model and a finite element analysis(FEA)simulation model are developed to study the power losses of the system,including copper loss in coils,semiconductor loss in circuits,and eddy current loss in transmission media.The characteristics of the power losses can provide guidelines to improve the efficiency of ICPT systems.Calculation results and simulation results are validated by relevant experiments of the prototype system.The output power of the prototype system is up to 45 W and the efficiency is up to 0.84.The preliminary results indicate that the efficiency will increase as the transmission power is raised by increasing the input voltage.When the output power reaches 500 W,the efficiency is expected to exceed 0.94.The efficiency can be further improved by choosing proper semiconductors and coils.The analysis methods prove effective in predicting the performance of similar ICPT systems and should be useful in designing new systems.
文摘Nanopowder of Cr:GGG and nanopowder of Cr,Nd:GGG with different concentrations of Cr3+ ranging from 0.1 at.% to 1.5 at.% were synthesized by the sol-gel method using acetic acid and ethylene glycol. Thermal gravimetric analysis and differential scanning calorimetry (TGA-DSC), X-ray diffraction (XRD) and photoluminescence spectroscopy were used to characterize the powder. The crystallite size was about 58 nm when treated at 1000 oC for 2 h. Cr3+ photoluminescence spectrum in GGG showed a broad band emission around 730 nm. The intensity of this band decreased when co-doped with Nd, indicating an efficient energy transfer from Cr3+ to Nd3+. Photoluminescence intensity of Nd in Cr,Nd:GGG at 1.06μm showed that the optimum concentration of Cr3+ was about 1 at.% (more or less) for 1 at.% Nd3+. This result was also confirmed by chromium fluorescence decay rate analysis. Energy transfer efficiency was found to be about 84% for 1 at.% concentration of each chromium and neodymium.
基金supported by the 100 Talents Program of the Chinese Academy of Sciences, National Natural Science Foundation of China (Nos. 21173226, 21376247)State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences (Nos. MPCS-2011-D-08, MPCS-2010-C-02)
文摘A 1-dodecanethiol-based phase-transfer protocol is developed for the extraction of noble metal ions from aqueous solution to a hydrocarbon phase, which calls for first mixing the aqueous metal ion solution with an ethanolic solution of 1-dodecanethiol, and then extracting the coordination compounds formed between noble metal ions and 1-dodecanethiol into a non-polar organic solvent. A number of characterization techniques, including inductively coupled plasma atomic emission spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis demonstrate that this protocol could be applied to extract a wide variety of noble metal ions from water to dichlorometh- ane with an efficiency of 〉96%, and has high selectivity for the separation of the noble metal ions from other transition metals. It is therefore an attractive alternative for the extraction of noble metals from water, soil, or waste printed circuit boards.
文摘This work provides an approach to determine the efficiency of T-ray detectors with a good accuracy in order to determine the concentrations of either naturally occurring or artificially prepared radionuclides. This approach is based on the efficiency transfer formula (ET), the effective solid angles, the self- absorptions of the source matrix, the attenuation by the source container and the detector housing materials on the detector efficiency. The experimental calibration process was done using radioactive (Cylindrical & Marinelli) sources, in different dimensions, that contain aqueous 152Eu radionuclide. The comparison point to a fine agreement between the experimental measured and calculated efficiencies for the (NaI & HPGe) detectors using volumetric radioactive sources.
基金supported by the National Key Research and Development Program of China (No.2021YFA0715700)the National Natural Science Foundation of China (Nos.1732011,U1932213,21975241)the University Synergy Innovation Program of Anhui Province,China (No.GXXT-2019-028).
文摘Porous solid scaffolds play key roles in preventing nanocatalysts from agglomeration,greatly maintaining the catalytic efficiency and stability of nanocatalysts.However,facile preparation of robust scaffolds with high mass transfer efficiency for loading nanocatalysts remains a major challenge.Here,we fabricate a wood-inspired shape-memory chitosan scaffold for loading Au nanoparticles to reduce 4-nitrophenol via a simple“freeze-casting and dip-adsorption”approach.The obtained catalytic scaffold highly resembles the unidirectional microchannel structure of natural wood,resulting in robust mechanical properties and outstanding water absorption capacity.Additionally,Au nanoparticles can be firmly and uniformly anchored on the inner surface of these microchannels via electrostatic interaction,forming numerous microreactors.This catalytic system exhibits a high 4-nitrophenol conversion rate of 99%in 5 s and impressive catalytic stability even after continuously treating with more than 3 L of highly concentrated 4-nitrophenol solution(1 mmol/L).Therefore,the wood-like catalytic system presented here demonstrates the potential to be applied in the field of water treatment and environmental protection.
基金the National Natural Science Foundation of China(Grant No.51808080)China Postdoctoral Science Foundation(No.2022M710830)+4 种基金Venture and Innovation Support Program for Chongqing Overseas Returnees(No.cx2022005)the Natural Science Foundation Project of CQ CSTC(No.CSTB2022NSCQ-MSX1267)Research Project of Chongqing Education Commission Foundation(No.KJQN201800826)Science and Technology Research Program of Chongqing Municipal Education Commission of China(No.KJZD-K202100801)Post-doctoral Program Funded by Chongqing,and Chongqing University Innovation Research Group project(No.CXQT21023).
文摘Deeply photocatalytic oxidation of NO-to-NO_(3)holds great promise for alleviating NO_(x) pollution.The major challenge of NO photo-oxidation is the highly in-situ generated NO_(2) concentration,and the formation of unstable nitrate species causes desorption to release NO_(2).In this study,SnO_(2) quantum dots and oxygen vacancies co-modified Zn_(2)SnO_(4)(ZSO-SnO_(2)-OVs)were prepared by a one-step hydrothermal procedure,the NO photo-oxidation was investigated by a combination of solid experimental and theoretical support.Impressively,spectroscopic measurements indicate that fast carrier dynamics can be achieved due to the electron transfer efficiency of ZSO-SnO_(2)-OVs reaching 99.99%,far outperforming the counterpart and previously reported photocatalysts.During NO oxidation,molecular NO/O_(2) and H2O are efficiently adsorbed/activated around OVs and SnO_(2) QDs,respectively.In-situ infrared measurements and calculated electron localized function disclose two main findings:(1)richly electrons enable NO promptly form NOinstead of toxic NO_(2) or NO^(+);(2)the generation of stable and undecomposed bidentate NO_(3)rather than bridging or monodentate one benefits the deep oxidation of NO via shifting reaction sites from O terminals for original ZSO to Sn ones for ZSO-SnO_(2)-OVs.The synergistic action of SnO_(2) QDs and OVs positively contributes to the NO oxidation performance enhancement(60.6%,0.1 g of sample)and high selectivity of NO to NO_(3)(99.2%).Results from this study advance the mechanistic understanding of NO photooxidation and its selectivity to NO_(3)over photocatalysts.
基金supported by the National Natural Science Foundation of China (No. 51473092)the Shanghai Rising-Star Program (No. 15QA1402500)
文摘Fabrication of efficient solid luminogens with tunable emission is both fundamentally significant and technically important. Herein, based on our previous strategy for the construction of efficient and multifunctional solid luminogens through the combination of diverse aggregation-induced emission (ALE) units with other functional moieties, a group of luminophores with electron donor-acceptor (D-A) structure and typical intramolecular charge transfer (ICT) characteristics, namely CZ-DCDPP, DPA-DCDPP and DBPA-DCDPP were synthesized and investigated. The presence of twisting and AlE-active 2,3- dicyano-S,6-diphenylpyrazine (DCDPP) moiety endows them highly emissive in the solid states, whereas the introduction of arylamines with varied electron-donating capacity and different conjugation render them with tunable solid emissions from green to red. While CZ-DCDPP and DPA-DCDPP solids exhibit distinct mechanochromism, both DPA-DCDPP and DBPA-DCDPP solids can generate efficient red emission. Owing to their high efficiency, remarkable thermal and morphological stabilities and moreover red emission, they are promising for diverse optoelectronic and biological applications.
基金This work was supported by a grant from Thailand Research Funding and Office of the Higher Education Commission,contract no.MRG6080261.
文摘Powder coating is an important process in the food industry,especially for snack foods such as potato chips,to create variety in food products.Electrostatic coating has been adopted in order to provide better transfer efficiency and lower the dust produced during coating.Studying the effect of electrode voltage on coating efficiency and evenness of baked potato chips using the developed electrostatic powder coating system was the main purpose of this research.Different types of NaCl(refined and table salts)were coated on baked potato chips at 0,30,40,50,60,and 70 kV.After coating with either refined or table salt,transfer efficiency,adhesion after coating,coating evenness and texture of samples were determined.Higher transfer efficiency,adhesion and coating evenness were observed when electrostatic coating was conducted at 30-50 kV.Most samples with higher transfer efficiency,adhesion and evenness were obtained after electrostatic coating.However,it did not significantly affect hardness of baked potato chips.
文摘Introduction THick Gas Electron Multiplier(THGEM)is considered in many UV photon detector applications.It has the capability of detecting single photon and imaging with high sensitivity.Operating parameters such as choice of gas mixture,pressure,drift field,drift gap,multiplication voltage,induction field and induction gap play an important role in deciding the spatial resolution of the detector.Detailed simulation study enables to optimize the above-mentioned parameters for a given THGEM-based imaging detector and hence to achieve improved performance for the same.Materials and methods Simulation,using ANSYS and Garfield++,starts with the release of primary electrons at random coordinates on the photocathode plane.They are tracked as they pass through the drift gap and THGEM hole till the electron cloud reaches anode plane.Distribution of electron cloud on the anode plane along X and Y axis is plotted in histogram and fitted with Gaussian function to determine spatial resolution.Ar/CO_(2)(70:30)mixture,which shows higher ETE and lower transverse diffusion,is chosen for this simulation study.Conclusion Transverse diffusion has a major impact on both ETE and the spatial resolution.Lower transverse diffusion coefficient is always desired for having better resolution as well as for ETE.It is found from the simulation study that higher gas pressure,lower drift field and induction field,smaller drift and induction gap can provide optimum detection efficiency with the best spatial resolution.The simulation method proposed here can also be extended to X-ray imaging detectors.