We have built an atomic force microscope using a quartz tuning fork as sensor. The excitation method we adopted, the electrical excitation, introduces stray capacitance into the signal-processing circuit. In this repo...We have built an atomic force microscope using a quartz tuning fork as sensor. The excitation method we adopted, the electrical excitation, introduces stray capacitance into the signal-processing circuit. In this report, we demonstrated a simple but effective method to compensate for this parasitic capacitance by adding a compensator circuit consisting of an inverting amplifier and a capacitor. The capacitor is connected in series with the inverting amplifier and the compensator is connected in parallel with the quartz tuning fork. The resonance curve of the system measured after adding the homemade compensator resembles that of a pure RLC circuit, meaning that the stray capacitance is successfully eliminated. Furthermore, we tried to use our equipment to measure PDMS sample and got clean data. This system can be further combined with confocal microscope and diamond with NV defect to build scanning NV magnetometry.展开更多
Parasitic capacitances associated with overhangs of the T-shape-gate enhancement-mode(E-mode)GaN-based power device,were investigated by frequency/voltage-dependent capacitance-voltage and inductive-load switching mea...Parasitic capacitances associated with overhangs of the T-shape-gate enhancement-mode(E-mode)GaN-based power device,were investigated by frequency/voltage-dependent capacitance-voltage and inductive-load switching measurements.The overhang capacitances induce a pinch-off voltage distinguished from that of the E-mode channel capacitance in the gate capacitance and the gatedrain capacitance characteristic curves.Frequency-and voltage-dependent tests confirm the instability caused by the trapping of interface/bulk states in the LPCVD-SiNx passivation dielectric.Circuit-level double pulse measurement also reveals its impact on switching transition for power switching applications.展开更多
Common mode current suppression is important to grid-connected photovoltaic(PV)systems and depends strongly on the value of the parasitic capacitance between the PV panel and the ground.Some parasitic capacitance mode...Common mode current suppression is important to grid-connected photovoltaic(PV)systems and depends strongly on the value of the parasitic capacitance between the PV panel and the ground.Some parasitic capacitance models have been proposed to evaluate the magnitude of the effective parasitic capacitance.However,the proposed model is only for the PV panels under dry and clean environmental conditions.The dependence of rain water on the capacitance is simply described rather than analyzing in detail.Furthermore,the effects of water are addressed quite differently in papers.Thus,this paper gives complete parasitic capacitance model of the PV panel considering the rain water.The effect of the water on the capacitance is systematically investigated through 3D finite element(FE)electromagnetic(EM)simulations and experiments.Accordingly,it is clarified how the water affects the parasitic capacitance and methods of minimization of the capacitance are proposed.展开更多
It is critical to build a wide-band circuit model to conduct research on the characteristics of the electromagnetic disturbance source during the localization of high voltage direct current(HVDC)technology.Parasitic c...It is critical to build a wide-band circuit model to conduct research on the characteristics of the electromagnetic disturbance source during the localization of high voltage direct current(HVDC)technology.Parasitic capacitance is most essential for modeling the equivalent circuit,so a fast and accurate computation of capacitance parameters plays a vital role.Because of the large size and complex structure of the converter equipment,it is impossible to obtain capacitance parameters by means of measurement or simulating calculation with finite element software.In this paper,a simplified method of capacitance extraction based on boundary element method is proposed,which can provide an efficient means of establishing simulation models.In the method presented,simulation model of the shield may not be chamfered.Consequently,the edge and corner of the shield do not need to be handled with a sphere,cylinder and other curved surface model.The availability of this method is demonstrated by comparing the capacitance parameters of chamfered shield with that of non-chamfered shield.展开更多
寄生电容是在电的电路存在的一个不可避免、通常讨厌的电容,并且它是最重要的秒顺序当设计摩擦电 nanogenerator (TENG ) 时,因为它的大小比得上 TENG 电容的大小,必须被考虑的非理想的效果。这份报纸通过当模特儿和模拟调查结构和 T...寄生电容是在电的电路存在的一个不可避免、通常讨厌的电容,并且它是最重要的秒顺序当设计摩擦电 nanogenerator (TENG ) 时,因为它的大小比得上 TENG 电容的大小,必须被考虑的非理想的效果。这份报纸通过当模特儿和模拟调查结构和 TENG 的表演优化,考虑寄生电容。寄生电容通常被发现在匹配 TENG 的抵抗,最大的输出力量,和结构的 figures-of-merit (FOM ) 的最佳上在 TENG,和它的效果引起严重性能降级彻底地被调查并且讨论。象差距和电极长度那样的重要结构的参数的最佳值为 TENG 的不同工作模式被决定,系统地表明怎么这些结构的参数作为寄生电容的函数改变的最佳。另外,寄生电容能改进金属的高度忍耐,这被表明独立模式的 TENG。这个工作为实际应用为结构和 TENG 的表演优化提供一个理论基础并且支持机械收获精力的技术的发展。展开更多
This paper presents an 11-bit 22-MS/s 0.6-mW successive approximation register(SAR) analog-todigital converter(ADC) using SMIC 65-nm low leakage(LL) CMOS technology with a 1.2 V supply voltage. To reduce the total cap...This paper presents an 11-bit 22-MS/s 0.6-mW successive approximation register(SAR) analog-todigital converter(ADC) using SMIC 65-nm low leakage(LL) CMOS technology with a 1.2 V supply voltage. To reduce the total capacitance and core area the split capacitor architecture is adopted. But in high resolution ADCs the parasitic capacitance in the LSB-side would decrease the linearity of the ADC and it is hard to calibrate. This paper proposes a parasitic capacitance compensation technique to cancel the effect with no calibration circuits.Moreover, dynamic circuits are used to minimize the switching power of the digital logic and also can reduce the latency time. The prototype chip realized an 11-bit SAR ADC fabricated in SMIC 65-nm CMOS technology with a core area of 300 200 m2. It shows a sampling rate of 22 MS/s and low power dissipation of 0.6 mW at a1.2 V supply voltage. At low input frequency the signal-to-noise-and-distortion ratio(SNDR) is 59.3 dB and the spurious-free dynamic range is 72.2 dB. The peak figure-of-merit is 36.4 fJ/conversion-step.展开更多
Parasitic nematodes have been reported as one of the major constraints to soybean production worldwide. The majority of nematodes are so-called “free-living” and feed mainly on bacteria, fungi, protozoa and other ne...Parasitic nematodes have been reported as one of the major constraints to soybean production worldwide. The majority of nematodes are so-called “free-living” and feed mainly on bacteria, fungi, protozoa and other nematodes. In Burkina Faso, the presence of parasitic nematodes has been reported in crops such as rice and sorghum. The objective of this study was to identify the genera and species of nematodes associated with soybean production in Burkina Faso. Investigations were carried out on 24 genotypes of a medium-maturity group of soybean at the Farako-Ba research station. Soil samples were taken from the trial soil before its installation. At harvest, soil samples with roots were taken from each genotype in the elementary plots. The composite sample is represented by 4 lots of soil samples with roots. Extractions and counts of nematodes were performed on the different lots. In total, 7 genera of plant-parasitic nematodes associated with soybean were identified. Among these genera, Pratylenchus (100% of infected genotypes), Helicotylenchus (97.28%) and Scutellonema (94.44%) were the most prevalent in terms of frequency and abundance. Some soybean genotypes were less susceptible to the genus Pratylenchus is known to be highly pathogenic in soybean. These were mainly the genotypes TGX2025-10E, TGX2023-3E and TGX2025-14E.展开更多
Sperm competition has been studied in numerous species as a representative example of postcopulatory sexual selection,where sampling sperm from male is the most basic and important step.Sperm collection can be tricky ...Sperm competition has been studied in numerous species as a representative example of postcopulatory sexual selection,where sampling sperm from male is the most basic and important step.Sperm collection can be tricky in birds,however,because unlike mammals,the genitals of birds are generally latent in the cloacal region and their characteristics vary among species.Various methods to collect sperm from different birds have been tested,such as cloacal massage,feces collection,and electro-stimulation,but their applicability varies depending on species.In this study,we introduced the urodeum stimulation method(UroS method)to collect sperm from Cuculus cuckoos,such as the Common Cuckoo(C.canorus).These species are expected to have interesting patterns of pair bonding and sperm competition because of their unique breeding strategy called brood parasitism;however,it remains unexplored.In this study,we described the application of our new method to expel semen from male common cuckoos,measured the volume of semen collected,checked the presence of sperm in the semen sample,and finally estimated its success rate among 82 males.Samples were successfully collected from 76 cuckoos(approximately 93%)and the colors and volumes of the samples were very diverse.Sperm was present in 43 of these samples(57%),showing a sperm observation rate approximately twice as high as that of the conventional cloacal massage method.We believe that this novel method will contribute to a better understanding of postcopulatory sexual selection in avian brood parasites and facilitate the process of sperm collection and artificial insemination in other medium-sized birds.展开更多
Heavy metal contamination has been regarded as an environmental variable that affects the efficiency of pest biological control,but the parasitic fitness of parasitoids under heavy metal stress is poorly understood.He...Heavy metal contamination has been regarded as an environmental variable that affects the efficiency of pest biological control,but the parasitic fitness of parasitoids under heavy metal stress is poorly understood.Herein,the effect of Cd exposure through the host pupa of Hyphantria cunea on the parasitic fitness of Chouioia cunea was investigated,and the mechanism by which Cd exposure affects the interaction between H.cunea and C.cunea from the perspective of innate immunity in host insect and the oxidative status in the parasitoid offspring was explored.Our results indicated that Cd can be transferred from the H.cunea pupae to the parasitoid offspring,and the transfer coefficient reflected biological amplification.There were no significant differences in the rates of parasitism success and offspring emergence between the untreated and Cd-treated groups.However,after parasitizing Cd-accumulated pupae,the parasitic fitness of offspring wasps(e.g.,the number,individual size and life span)decreased significantly.Under Cd exposure,the cellular and humoral immunity of H.cunea pupae decreased significantly.Compared with the untreated group,the H_(2)O_(2)content of parasitoid offspring in the Cd-treated group was significantly increased.Cd exposure significantly inhibited superoxide dismutase activity in parasitoid offspring,but the contents of ascorbic acid and glutathione were significantly increased by Cd stress.Taken together,these results indicate that Cd exposure reduces the cyclic utilization efficiency of C.cunea on H.cunea pupae.The oxidative status of parasitoid offspring triggered by Cd exposure could be responsible for the reduced parasitic fitness of C.cunea on Cd-accumulated H.cunea pupae.展开更多
Background: There is no study that estimates the prevalence of vernal keratoconjunctivitis and the association between vernal keratoconjunctivitis and intestinal parasitic infestation in our setting. Purpose: This stu...Background: There is no study that estimates the prevalence of vernal keratoconjunctivitis and the association between vernal keratoconjunctivitis and intestinal parasitic infestation in our setting. Purpose: This study aimed to estimate the vernal keratoconjunctivitis prevalence, describe the profile of sensitization and determine the association between vernal keratoconjunctivitis disease and intestinal parasitic infestation in school children of Kinshasa during the scholar year from 2022 to 2023. Methods: An observational, cross-sectional study was performed from September 2022 to June 2023. The children with vernal keratoconjunctivitis were recruited by using the four-stage probability sampling technique. Children attending in the school children of Kinshasa with vernal keratoconjunctivitis were enrolled in the classroom and underwent a clinical examination and skin prick test for 11 allergens and stool examination direct with microscope in the Laboratory. Data were entered in Microsoft Sheets using SPSS version 20.0. The Chi-square test was used to compare the sex, age groups, home environment (grow trees and/or flowers around the yard), dampness in the house, keeping pets (cat and/or dog), number of people per household, number of people sharing a bedroom and intestinal parasitic infestation. The significant level was set to a value of p Results: A total of 28,800 students from four-stage probabilist sampling technique in school of Kinshasa were included, and 2100 students had symptoms according to the vernal keratoconjunctivitis-related symptom questionnaire. Children with vernal keratoconjunctivitis were enrolled and the mean age ± standard was 7.2 ± 3.7 years, with a prevalence of 7.2% and gender was three boys for one girl. All vernal keratoconjunctivitis children recruited in urban and rural part had 33.1% positive skin prick test (SPT) and 67.9% showed polysensitization. Children an urban part was more sensitized than rural respectively with Dermatophagoides pteronyssinus 28.1% vs 28.9%, p = 0.00001, Blomia tropicalis. 15.9% vs 14.9%, p = 0.00001 and cockroach 12% vs 13%, p = 0.00001 in both parts. Vernal keratoconjunctivitis children in rural part were more affected to the intestinal parasite than urban with Ascaris lumbricoides 14% vs 18.3%, p = 0.0006, followed by Ancylostoma duodenale 9.5% vs 12.5%, p = 0.003, Anguillule 7.9% vs 10.1%, p = 0.001, Oxyure 5.7% vs 8.2%, p = 0.0001 and Trichuris trichiura 2.6% vs 3.3%, p = 0.0009. Conclusion: This study outlines that the prevalence of vernal keratoconjunctivitis was 7.2% and 33.1% of children attending for vernal keratoconjunctivitis in school children had a positive skin prick test to at least one allergen, in particular for Dermatophagoides pteronyssinus, Blomia tropicalis and cockroach. The most common intestinal parasitic infestation was Ascaris lumbricoides, Ancylostoma duodenale, Anguillule and Trichuris trichiura.展开更多
Supercapacitors formed from porous carbon and graphene-oxide(GO)materials are usually dominated by either electric double-layer capacitance,pseudo-capacitance,or both.Due to these combined features,reduced GO material...Supercapacitors formed from porous carbon and graphene-oxide(GO)materials are usually dominated by either electric double-layer capacitance,pseudo-capacitance,or both.Due to these combined features,reduced GO materials have been shown to offer superior capacitance over typical nanoporous carbon materials;however,there is a significant variation in reported values,ranging between 25 and 350 F g^(−1).This undermines the structure(e.g.,oxygen functionality and/or surface area)-performance relationships for optimization of cost and scalable factors.This work demonstrates important structure-controlled charge storage relationships.For this,a series of exfoliated graphene(EG)derivatives are produced via thermal-shock exfoliation of GO precursors and following controlled graphitization of EG(GEG)generates materials with varied amounts of porosity,redox-active oxygen groups and graphitic components.Experimental results show significantly varied capacitance values between 30 and 250 F g^(−1)at 1.0 A g^(−1)in GEG structures;this suggests that for a given specific surface area the redox-active and hydrophilic oxygen content can boost the capacitance to 250–300%higher compared to typical mesoporous carbon materials.GEGs with identical oxygen functionality show a surface area governed capacitance.This allows to establish direct structure-performance relationships between 1)redox-active oxygen functional concentration and capacitance and 2)surface area and capacitance.展开更多
An rGO−like carbon compound has been synthesized from biomass,i.e.,old coconut shell,by a carbonization process followed by heating at 400°C for 5 h.The nitrogen doping was achieved by adding the urea(CH4N2O)and ...An rGO−like carbon compound has been synthesized from biomass,i.e.,old coconut shell,by a carbonization process followed by heating at 400°C for 5 h.The nitrogen doping was achieved by adding the urea(CH4N2O)and stirring at 70°C for 14 h.The morphology and structure of the rGO-like carbon were investigated by electron microscopies and Raman spectroscopy.The presence of C-N functional groups was analyzed by Fourier transform infrared and synchrotron X-ray photoemission spectroscopy,while the particle and the specific capacitance were measured by particle sizer and cyclic voltammetry.The highest specific capacitance of 72.78 F/g is achieved by the sample with 20%urea,having the smallest particles size and the largest surface area.The corresponding sample has shown to be constituted by the appropriate amount of C–N pyrrolic and pyridinic defects.展开更多
Supercapacitors are appealing energy storage devices for their promising features like high power density,outstanding cycling stability,and a quick charge–discharge cycle.The exceptional life cycle and ultimate power...Supercapacitors are appealing energy storage devices for their promising features like high power density,outstanding cycling stability,and a quick charge–discharge cycle.The exceptional life cycle and ultimate power capability of supercapacitors are needed in the transportation and renewable energy generation sectors.Hence,predicting the capacitance and lifecycle of supercapacitors is significant for selecting the suitable material and planning replacement intervals for supercapacitors.In addition,system failures can be better addressed by accurately forecasting the lifecycle of SCs.Recently,the use of machine learning for performance prediction of energy storage materials has drawn increasing attention from researchers globally because of its superiority in prediction accuracy,time efficiency,and costeffectiveness.This article presents a detailed review of the progress and advancement of ML techniques for the prediction of capacitance and remaining useful life(RUL)of supercapacitors.The review starts with an introduction to supercapacitor materials and ML applications in energy storage devices,followed by workflow for ML model building for supercapacitor materials.Then,the summary of machine learning applications for the prediction of capacitance and RUL of different supercapacitor materials including EDLCs(carbon based materials),pesudocapacitive(oxides and composites)and hybrid materials is presented.Finally,the general perspective for future directions is also presented.展开更多
Capacitance extraction is one of the key issues in integrated circuits and also a typical electrostatic problem.The dual discrete geometric method(DGM) is investigated to provide relative solutions in two-dimensional ...Capacitance extraction is one of the key issues in integrated circuits and also a typical electrostatic problem.The dual discrete geometric method(DGM) is investigated to provide relative solutions in two-dimensional unstructured mesh space.The energy complementary characteristic and quick field energy computation thereof based on it are emphasized.Contrastive analysis between the dual finite element methods and the dual DGMs are presented both from theoretical derivation and through case studies.The DGM,taking the scalar potential as unknown on dual interlocked meshes,with simple form and good accuracy,is expected to be one of the mainstreaming methods in associated areas.展开更多
Biomass-derived carbon has demonstrated great potentials as advanced electrode for capacitive deionization(CDI),owing to good electroconductivity,easy availability,intrinsic pores/channels.However,conventional simple ...Biomass-derived carbon has demonstrated great potentials as advanced electrode for capacitive deionization(CDI),owing to good electroconductivity,easy availability,intrinsic pores/channels.However,conventional simple pyrolysis of biomass always generates inadequate porosity with limited surface area.Moreover,biomass-derived carbon also suffers from poor wettability and single physical adsorption of ions,resulting in limited desalination performance.Herein,pore structure optimization and element co-doping are integrated on banana peels(BP)-derived carbon to construct hierarchically porous and B,N co-doped carbon with large ions-accessible surface area.A unique expansionactivation(EA)strategy is proposed to modulate the porosity and specific surface area of carbon.Furthermore,B,N co-doping could increase the ions-accessible sites with improved hydrophilicity,and promote ions adsorption.Benefitting from the synergistic effect of hierarchical porosity and B,N co-doping,the resultant electrode manifest enhanced CDI performance for NaCl with large desalination capacity(29.5 mg g^(-1)),high salt adsorption rate(6.2 mg g^(-1)min^(-1)),and versatile adsorption ability for other salts.Density functional theory reveals the enhanced deionization mechanism by pore and B,N co-doping.This work proposes a facile EA strategy for pore structure modulation of biomass-derived carbon,and demonstrates great potentials of integrating pore and heteroatoms-doping on constructing high-performance CDI electrode.展开更多
Nickel-rich transition-metal oxides are widely regarded as promising cathode materials for high-energydensity lithium-ion batteries for emerging electric vehicles. However, achieving high energy density in Ni-rich cat...Nickel-rich transition-metal oxides are widely regarded as promising cathode materials for high-energydensity lithium-ion batteries for emerging electric vehicles. However, achieving high energy density in Ni-rich cathodes is accompanied by substantial safety and cycle-life obstacles. The major issues of Ni-rich cathodes at high working potentials are originated from the unstable cathode-electrolyte interface, while the underlying mechanism of parasitic reactions towards surface reconstructions of cathode materials is not well understood. In this work, we controlled the Li_(2)CO_(3) impurity content on LiNi_(0.83)Mn_(0.1)Co_(0.07)O_(2) cathodes using air, tank-air, and O_(2) synthesis environments. Home-built high-precision leakage current and on-line electrochemical mass spectroscopy experiments verify that Li_(2)CO_(3) impurity is a significant promoter of parasitic reactions on Ni-rich cathodes. The rate of parasitic reactions is strongly correlated to Li_(2)CO_(3) content and severe performance deterioration of Ni83 cathodes.The post-mortem characterizations via high-resolution transition electron microscope and X-ray photoelectron spectroscopy depth profiles reveal that parasitic reactions promote more Ni reduction and O deficiency and even rock-salt phase transformation at the surface of cathode materials. Our observation suggests that surface reconstructions have a strong affiliation to parasitic reactions that create chemically acidic environment to etch away the lattice oxygen and offer the electrical charge to reduce the valence state of transition metal. Thus, this study advances our understanding on surface reconstructions of Nirich cathodes and prepares us for searching for rational strategies.展开更多
The steep sub-threshold swing of a tunneling field-effect transistor(TFET)makes it one of the best candidates for lowpower nanometer devices.However,the low driving capability of TFETs prevents their application in in...The steep sub-threshold swing of a tunneling field-effect transistor(TFET)makes it one of the best candidates for lowpower nanometer devices.However,the low driving capability of TFETs prevents their application in integrated circuits.In this study,an innovative gate-all-around(GAA)TFET,which represents a negative capacitance GAA gate-to-source overlap TFET(NCGAA-SOL-TFET),is proposed to increase the driving current.The proposed NCGAA-SOL-TFET is developed based on technology computer-aided design(TCAD)simulations.The proposed structure can solve the problem of the insufficient driving capability of conventional TFETs and is suitable for sub-3-nm nodes.In addition,due to the negative capacitance effect,the surface potential of the channel can be amplified,thus enhancing the driving current.The gateto-source overlap(SOL)technique is used for the first time in an NCGAA-TFET to increase the band-to-band tunneling rate and tunneling area at the silicon-germanium heterojunction.By optimizing the design of the proposed structure via adjusting the SOL length and the ferroelectric layer thickness,a sufficiently large on-state current of 17.20μA can be achieved and the threshold voltage can be reduced to 0.31 V with a sub-threshold swing of 44.98 mV/decade.Finally,the proposed NCGAA-SOL-TFET can overcome the Boltzmann limit-related problem,achieving a driving current that is comparable to that of the traditional complementary metal-oxide semiconductor devices.展开更多
The magnetic field generated in the air gap of the cage asynchronous machine and the harmonics of the magnetomotive forces creating that magnetic field,as well as the synchronous parasitic torques,radial magnetic forc...The magnetic field generated in the air gap of the cage asynchronous machine and the harmonics of the magnetomotive forces creating that magnetic field,as well as the synchronous parasitic torques,radial magnetic forces have been discussed in great detail in the literature,but always separately,for a long time.However,systematization of the phenomenon still awaits.Therefore,it is worth summarizing the completeness of the phenomena in a single study–with a new approach at the same time-in order to reveal the relationships between them.The role of rotor slot number is emphasized much more than before.New formulas derived for both synchronous torques and radial magnetic forces are used for further investigation.It will be shown that both phenomena in subject must be treated together.Formulas will be provided to take into account attenuation.Design guide will be provided to avoid dangerous rotor slot numbers.It will be shown that the generation of synchronous torques and radial magnetic forces do not depend–in this new approach-on the slot combination,but on the rotor slot number itself.展开更多
The magnetic field generated in the air gap of the cage asynchronous machine and the harmonics of the magnetomotive forces creating that magnetic field, as well as the related differential leakage, attenuation, asynch...The magnetic field generated in the air gap of the cage asynchronous machine and the harmonics of the magnetomotive forces creating that magnetic field, as well as the related differential leakage, attenuation, asynchronous parasitic torques have been discussed in great detail in the literature, but always separately, for a long time. However, systematization of the phenomenon still awaits. Therefore, it is worth summarizing the completeness of the phenomena in a single study – with a new approach at the same time-in order to reveal the relationships between them. The role of rotor slot number is emphasized much more than before. An existing, commonly used, but still impractical basic figure has been modified to more clearly demonstrate the response of the rotor for the harmonics of the stator. The need to treat differential leakage, asynchronous parasitic torques and attenuation together will be demonstrated: new formula for asynchronous parasitic torque is derived;the long-used characteristic curves for differential leakage and attenuation used separately so far was merged into one, correct curve in order to provide a correct design guide for the engineers.展开更多
Sensitivity analysis methods help to deal with the challenges of process variation in extraction of parasitic capacitances in an integrated circuit. The dual discrete geometric methods(DGMs), which have been recently ...Sensitivity analysis methods help to deal with the challenges of process variation in extraction of parasitic capacitances in an integrated circuit. The dual discrete geometric methods(DGMs), which have been recently utilized to extract parasitic capacitances, are reviewed. The computation method based on the dual DGMs for sensitivities of capacitances with respect to the given process parameters is presented. As the dual DGMs utilize scalar electric potential is unknown, the capacitances are obtained effectively, and then the sensitivities are calculated conveniently.展开更多
文摘We have built an atomic force microscope using a quartz tuning fork as sensor. The excitation method we adopted, the electrical excitation, introduces stray capacitance into the signal-processing circuit. In this report, we demonstrated a simple but effective method to compensate for this parasitic capacitance by adding a compensator circuit consisting of an inverting amplifier and a capacitor. The capacitor is connected in series with the inverting amplifier and the compensator is connected in parallel with the quartz tuning fork. The resonance curve of the system measured after adding the homemade compensator resembles that of a pure RLC circuit, meaning that the stray capacitance is successfully eliminated. Furthermore, we tried to use our equipment to measure PDMS sample and got clean data. This system can be further combined with confocal microscope and diamond with NV defect to build scanning NV magnetometry.
基金the National Natural Science Foundation of China under Grant 61822407,Grant 61527816,Grant 11634002,Grant 61631021,Grant 62074161,Grant 62004213,and Grant U20A20208in part by the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(CAS)under Grant QYZDB-SSW-JSC012+2 种基金in part by the Youth Innovation Promotion Association of CASin part by the University of CASthe Opening Project of Key Laboratory of Microelectronic Devices&Integrated Technology,Institute of Microelectronics,CAS.
文摘Parasitic capacitances associated with overhangs of the T-shape-gate enhancement-mode(E-mode)GaN-based power device,were investigated by frequency/voltage-dependent capacitance-voltage and inductive-load switching measurements.The overhang capacitances induce a pinch-off voltage distinguished from that of the E-mode channel capacitance in the gate capacitance and the gatedrain capacitance characteristic curves.Frequency-and voltage-dependent tests confirm the instability caused by the trapping of interface/bulk states in the LPCVD-SiNx passivation dielectric.Circuit-level double pulse measurement also reveals its impact on switching transition for power switching applications.
文摘Common mode current suppression is important to grid-connected photovoltaic(PV)systems and depends strongly on the value of the parasitic capacitance between the PV panel and the ground.Some parasitic capacitance models have been proposed to evaluate the magnitude of the effective parasitic capacitance.However,the proposed model is only for the PV panels under dry and clean environmental conditions.The dependence of rain water on the capacitance is simply described rather than analyzing in detail.Furthermore,the effects of water are addressed quite differently in papers.Thus,this paper gives complete parasitic capacitance model of the PV panel considering the rain water.The effect of the water on the capacitance is systematically investigated through 3D finite element(FE)electromagnetic(EM)simulations and experiments.Accordingly,it is clarified how the water affects the parasitic capacitance and methods of minimization of the capacitance are proposed.
文摘It is critical to build a wide-band circuit model to conduct research on the characteristics of the electromagnetic disturbance source during the localization of high voltage direct current(HVDC)technology.Parasitic capacitance is most essential for modeling the equivalent circuit,so a fast and accurate computation of capacitance parameters plays a vital role.Because of the large size and complex structure of the converter equipment,it is impossible to obtain capacitance parameters by means of measurement or simulating calculation with finite element software.In this paper,a simplified method of capacitance extraction based on boundary element method is proposed,which can provide an efficient means of establishing simulation models.In the method presented,simulation model of the shield may not be chamfered.Consequently,the edge and corner of the shield do not need to be handled with a sphere,cylinder and other curved surface model.The availability of this method is demonstrated by comparing the capacitance parameters of chamfered shield with that of non-chamfered shield.
文摘寄生电容是在电的电路存在的一个不可避免、通常讨厌的电容,并且它是最重要的秒顺序当设计摩擦电 nanogenerator (TENG ) 时,因为它的大小比得上 TENG 电容的大小,必须被考虑的非理想的效果。这份报纸通过当模特儿和模拟调查结构和 TENG 的表演优化,考虑寄生电容。寄生电容通常被发现在匹配 TENG 的抵抗,最大的输出力量,和结构的 figures-of-merit (FOM ) 的最佳上在 TENG,和它的效果引起严重性能降级彻底地被调查并且讨论。象差距和电极长度那样的重要结构的参数的最佳值为 TENG 的不同工作模式被决定,系统地表明怎么这些结构的参数作为寄生电容的函数改变的最佳。另外,寄生电容能改进金属的高度忍耐,这被表明独立模式的 TENG。这个工作为实际应用为结构和 TENG 的表演优化提供一个理论基础并且支持机械收获精力的技术的发展。
基金Project sponsored by the Natural Science Foundation of China(No.61006025)the Special Research Funds for Doctoral Program of Higher Education of China(No.20100071110026)the National Science&Technology Major Project of China(No.2012ZX03001020-003)
文摘This paper presents an 11-bit 22-MS/s 0.6-mW successive approximation register(SAR) analog-todigital converter(ADC) using SMIC 65-nm low leakage(LL) CMOS technology with a 1.2 V supply voltage. To reduce the total capacitance and core area the split capacitor architecture is adopted. But in high resolution ADCs the parasitic capacitance in the LSB-side would decrease the linearity of the ADC and it is hard to calibrate. This paper proposes a parasitic capacitance compensation technique to cancel the effect with no calibration circuits.Moreover, dynamic circuits are used to minimize the switching power of the digital logic and also can reduce the latency time. The prototype chip realized an 11-bit SAR ADC fabricated in SMIC 65-nm CMOS technology with a core area of 300 200 m2. It shows a sampling rate of 22 MS/s and low power dissipation of 0.6 mW at a1.2 V supply voltage. At low input frequency the signal-to-noise-and-distortion ratio(SNDR) is 59.3 dB and the spurious-free dynamic range is 72.2 dB. The peak figure-of-merit is 36.4 fJ/conversion-step.
文摘Parasitic nematodes have been reported as one of the major constraints to soybean production worldwide. The majority of nematodes are so-called “free-living” and feed mainly on bacteria, fungi, protozoa and other nematodes. In Burkina Faso, the presence of parasitic nematodes has been reported in crops such as rice and sorghum. The objective of this study was to identify the genera and species of nematodes associated with soybean production in Burkina Faso. Investigations were carried out on 24 genotypes of a medium-maturity group of soybean at the Farako-Ba research station. Soil samples were taken from the trial soil before its installation. At harvest, soil samples with roots were taken from each genotype in the elementary plots. The composite sample is represented by 4 lots of soil samples with roots. Extractions and counts of nematodes were performed on the different lots. In total, 7 genera of plant-parasitic nematodes associated with soybean were identified. Among these genera, Pratylenchus (100% of infected genotypes), Helicotylenchus (97.28%) and Scutellonema (94.44%) were the most prevalent in terms of frequency and abundance. Some soybean genotypes were less susceptible to the genus Pratylenchus is known to be highly pathogenic in soybean. These were mainly the genotypes TGX2025-10E, TGX2023-3E and TGX2025-14E.
基金financially supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by The Ministry of Education(NRF2020R1I1A2063567)。
文摘Sperm competition has been studied in numerous species as a representative example of postcopulatory sexual selection,where sampling sperm from male is the most basic and important step.Sperm collection can be tricky in birds,however,because unlike mammals,the genitals of birds are generally latent in the cloacal region and their characteristics vary among species.Various methods to collect sperm from different birds have been tested,such as cloacal massage,feces collection,and electro-stimulation,but their applicability varies depending on species.In this study,we introduced the urodeum stimulation method(UroS method)to collect sperm from Cuculus cuckoos,such as the Common Cuckoo(C.canorus).These species are expected to have interesting patterns of pair bonding and sperm competition because of their unique breeding strategy called brood parasitism;however,it remains unexplored.In this study,we described the application of our new method to expel semen from male common cuckoos,measured the volume of semen collected,checked the presence of sperm in the semen sample,and finally estimated its success rate among 82 males.Samples were successfully collected from 76 cuckoos(approximately 93%)and the colors and volumes of the samples were very diverse.Sperm was present in 43 of these samples(57%),showing a sperm observation rate approximately twice as high as that of the conventional cloacal massage method.We believe that this novel method will contribute to a better understanding of postcopulatory sexual selection in avian brood parasites and facilitate the process of sperm collection and artificial insemination in other medium-sized birds.
基金the project funded by the Natural Science Foundation of Heilongjiang Province,China(YQ2022C006)National Natural Science Foundation of China(32101526)。
文摘Heavy metal contamination has been regarded as an environmental variable that affects the efficiency of pest biological control,but the parasitic fitness of parasitoids under heavy metal stress is poorly understood.Herein,the effect of Cd exposure through the host pupa of Hyphantria cunea on the parasitic fitness of Chouioia cunea was investigated,and the mechanism by which Cd exposure affects the interaction between H.cunea and C.cunea from the perspective of innate immunity in host insect and the oxidative status in the parasitoid offspring was explored.Our results indicated that Cd can be transferred from the H.cunea pupae to the parasitoid offspring,and the transfer coefficient reflected biological amplification.There were no significant differences in the rates of parasitism success and offspring emergence between the untreated and Cd-treated groups.However,after parasitizing Cd-accumulated pupae,the parasitic fitness of offspring wasps(e.g.,the number,individual size and life span)decreased significantly.Under Cd exposure,the cellular and humoral immunity of H.cunea pupae decreased significantly.Compared with the untreated group,the H_(2)O_(2)content of parasitoid offspring in the Cd-treated group was significantly increased.Cd exposure significantly inhibited superoxide dismutase activity in parasitoid offspring,but the contents of ascorbic acid and glutathione were significantly increased by Cd stress.Taken together,these results indicate that Cd exposure reduces the cyclic utilization efficiency of C.cunea on H.cunea pupae.The oxidative status of parasitoid offspring triggered by Cd exposure could be responsible for the reduced parasitic fitness of C.cunea on Cd-accumulated H.cunea pupae.
文摘Background: There is no study that estimates the prevalence of vernal keratoconjunctivitis and the association between vernal keratoconjunctivitis and intestinal parasitic infestation in our setting. Purpose: This study aimed to estimate the vernal keratoconjunctivitis prevalence, describe the profile of sensitization and determine the association between vernal keratoconjunctivitis disease and intestinal parasitic infestation in school children of Kinshasa during the scholar year from 2022 to 2023. Methods: An observational, cross-sectional study was performed from September 2022 to June 2023. The children with vernal keratoconjunctivitis were recruited by using the four-stage probability sampling technique. Children attending in the school children of Kinshasa with vernal keratoconjunctivitis were enrolled in the classroom and underwent a clinical examination and skin prick test for 11 allergens and stool examination direct with microscope in the Laboratory. Data were entered in Microsoft Sheets using SPSS version 20.0. The Chi-square test was used to compare the sex, age groups, home environment (grow trees and/or flowers around the yard), dampness in the house, keeping pets (cat and/or dog), number of people per household, number of people sharing a bedroom and intestinal parasitic infestation. The significant level was set to a value of p Results: A total of 28,800 students from four-stage probabilist sampling technique in school of Kinshasa were included, and 2100 students had symptoms according to the vernal keratoconjunctivitis-related symptom questionnaire. Children with vernal keratoconjunctivitis were enrolled and the mean age ± standard was 7.2 ± 3.7 years, with a prevalence of 7.2% and gender was three boys for one girl. All vernal keratoconjunctivitis children recruited in urban and rural part had 33.1% positive skin prick test (SPT) and 67.9% showed polysensitization. Children an urban part was more sensitized than rural respectively with Dermatophagoides pteronyssinus 28.1% vs 28.9%, p = 0.00001, Blomia tropicalis. 15.9% vs 14.9%, p = 0.00001 and cockroach 12% vs 13%, p = 0.00001 in both parts. Vernal keratoconjunctivitis children in rural part were more affected to the intestinal parasite than urban with Ascaris lumbricoides 14% vs 18.3%, p = 0.0006, followed by Ancylostoma duodenale 9.5% vs 12.5%, p = 0.003, Anguillule 7.9% vs 10.1%, p = 0.001, Oxyure 5.7% vs 8.2%, p = 0.0001 and Trichuris trichiura 2.6% vs 3.3%, p = 0.0009. Conclusion: This study outlines that the prevalence of vernal keratoconjunctivitis was 7.2% and 33.1% of children attending for vernal keratoconjunctivitis in school children had a positive skin prick test to at least one allergen, in particular for Dermatophagoides pteronyssinus, Blomia tropicalis and cockroach. The most common intestinal parasitic infestation was Ascaris lumbricoides, Ancylostoma duodenale, Anguillule and Trichuris trichiura.
基金supported by EPSRC(grants of EP/R511638/1,EP/S018204/2,EP/R023581/1,EP/W03395X/1,EP/W033321/1)the Science Specialty Program of Sichuan University(Grant.No.2020SCUNL210)+2 种基金The Royal Academy of Engineering is acknowledged for the financial support of Shearing(Ci ET171859)Brett(RCSRF2021/13/53)under the Research Chairs and Senior Research Fel owships schemethe National Physical Laboratory(NPL)and HORIBA MIRA for the support of his RAEng Research Chair
文摘Supercapacitors formed from porous carbon and graphene-oxide(GO)materials are usually dominated by either electric double-layer capacitance,pseudo-capacitance,or both.Due to these combined features,reduced GO materials have been shown to offer superior capacitance over typical nanoporous carbon materials;however,there is a significant variation in reported values,ranging between 25 and 350 F g^(−1).This undermines the structure(e.g.,oxygen functionality and/or surface area)-performance relationships for optimization of cost and scalable factors.This work demonstrates important structure-controlled charge storage relationships.For this,a series of exfoliated graphene(EG)derivatives are produced via thermal-shock exfoliation of GO precursors and following controlled graphitization of EG(GEG)generates materials with varied amounts of porosity,redox-active oxygen groups and graphitic components.Experimental results show significantly varied capacitance values between 30 and 250 F g^(−1)at 1.0 A g^(−1)in GEG structures;this suggests that for a given specific surface area the redox-active and hydrophilic oxygen content can boost the capacitance to 250–300%higher compared to typical mesoporous carbon materials.GEGs with identical oxygen functionality show a surface area governed capacitance.This allows to establish direct structure-performance relationships between 1)redox-active oxygen functional concentration and capacitance and 2)surface area and capacitance.
基金supported by“Hibah Penelitian Dasar Kompetitif Nasional”,Ministry of Education,Culture,Research and Technology,Indonesia,2021–2022(D).The use of the synchrotron XPES facility at SLRI(Public Organization),Thailand,and some experimental facilities at UNIMAP and UPM,Malaysia,would also be appreciated.
文摘An rGO−like carbon compound has been synthesized from biomass,i.e.,old coconut shell,by a carbonization process followed by heating at 400°C for 5 h.The nitrogen doping was achieved by adding the urea(CH4N2O)and stirring at 70°C for 14 h.The morphology and structure of the rGO-like carbon were investigated by electron microscopies and Raman spectroscopy.The presence of C-N functional groups was analyzed by Fourier transform infrared and synchrotron X-ray photoemission spectroscopy,while the particle and the specific capacitance were measured by particle sizer and cyclic voltammetry.The highest specific capacitance of 72.78 F/g is achieved by the sample with 20%urea,having the smallest particles size and the largest surface area.The corresponding sample has shown to be constituted by the appropriate amount of C–N pyrrolic and pyridinic defects.
基金Shivaji University,Kolhapur for financial assistance through Research Strengthening Scheme。
文摘Supercapacitors are appealing energy storage devices for their promising features like high power density,outstanding cycling stability,and a quick charge–discharge cycle.The exceptional life cycle and ultimate power capability of supercapacitors are needed in the transportation and renewable energy generation sectors.Hence,predicting the capacitance and lifecycle of supercapacitors is significant for selecting the suitable material and planning replacement intervals for supercapacitors.In addition,system failures can be better addressed by accurately forecasting the lifecycle of SCs.Recently,the use of machine learning for performance prediction of energy storage materials has drawn increasing attention from researchers globally because of its superiority in prediction accuracy,time efficiency,and costeffectiveness.This article presents a detailed review of the progress and advancement of ML techniques for the prediction of capacitance and remaining useful life(RUL)of supercapacitors.The review starts with an introduction to supercapacitor materials and ML applications in energy storage devices,followed by workflow for ML model building for supercapacitor materials.Then,the summary of machine learning applications for the prediction of capacitance and RUL of different supercapacitor materials including EDLCs(carbon based materials),pesudocapacitive(oxides and composites)and hybrid materials is presented.Finally,the general perspective for future directions is also presented.
基金supported by the National Science Foundation of China(No.51207150)the Director Foundation of Institute of Microelectronics of Chinese Academy of Sciences(Nos.Y2SF017001,Y3SZ0701)
文摘Capacitance extraction is one of the key issues in integrated circuits and also a typical electrostatic problem.The dual discrete geometric method(DGM) is investigated to provide relative solutions in two-dimensional unstructured mesh space.The energy complementary characteristic and quick field energy computation thereof based on it are emphasized.Contrastive analysis between the dual finite element methods and the dual DGMs are presented both from theoretical derivation and through case studies.The DGM,taking the scalar potential as unknown on dual interlocked meshes,with simple form and good accuracy,is expected to be one of the mainstreaming methods in associated areas.
基金We gratefully acknowledge financial supports from the National Natural Science Foundation of China(No.52202371,51905125,52102364)the Natural Science Foundation of Shandong Province(No.ZR2020QE066)+2 种基金Opening Project of State Key Laboratory of Advanced Technology for Float Glass(No.2020KF08)SDUT&Zibo City Integration Development Project(No.2021SNPT0045)the fellowship of China Postdoctoral Science Foundation(No.2020M672081).
文摘Biomass-derived carbon has demonstrated great potentials as advanced electrode for capacitive deionization(CDI),owing to good electroconductivity,easy availability,intrinsic pores/channels.However,conventional simple pyrolysis of biomass always generates inadequate porosity with limited surface area.Moreover,biomass-derived carbon also suffers from poor wettability and single physical adsorption of ions,resulting in limited desalination performance.Herein,pore structure optimization and element co-doping are integrated on banana peels(BP)-derived carbon to construct hierarchically porous and B,N co-doped carbon with large ions-accessible surface area.A unique expansionactivation(EA)strategy is proposed to modulate the porosity and specific surface area of carbon.Furthermore,B,N co-doping could increase the ions-accessible sites with improved hydrophilicity,and promote ions adsorption.Benefitting from the synergistic effect of hierarchical porosity and B,N co-doping,the resultant electrode manifest enhanced CDI performance for NaCl with large desalination capacity(29.5 mg g^(-1)),high salt adsorption rate(6.2 mg g^(-1)min^(-1)),and versatile adsorption ability for other salts.Density functional theory reveals the enhanced deionization mechanism by pore and B,N co-doping.This work proposes a facile EA strategy for pore structure modulation of biomass-derived carbon,and demonstrates great potentials of integrating pore and heteroatoms-doping on constructing high-performance CDI electrode.
基金supported by the U.S. Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Officesupported by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office, under Contract No. DE-SC0012704+1 种基金supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract DE-AC02-06CH11357supported by the Vehicle Technologies Office of the U.S. Department of Energy。
文摘Nickel-rich transition-metal oxides are widely regarded as promising cathode materials for high-energydensity lithium-ion batteries for emerging electric vehicles. However, achieving high energy density in Ni-rich cathodes is accompanied by substantial safety and cycle-life obstacles. The major issues of Ni-rich cathodes at high working potentials are originated from the unstable cathode-electrolyte interface, while the underlying mechanism of parasitic reactions towards surface reconstructions of cathode materials is not well understood. In this work, we controlled the Li_(2)CO_(3) impurity content on LiNi_(0.83)Mn_(0.1)Co_(0.07)O_(2) cathodes using air, tank-air, and O_(2) synthesis environments. Home-built high-precision leakage current and on-line electrochemical mass spectroscopy experiments verify that Li_(2)CO_(3) impurity is a significant promoter of parasitic reactions on Ni-rich cathodes. The rate of parasitic reactions is strongly correlated to Li_(2)CO_(3) content and severe performance deterioration of Ni83 cathodes.The post-mortem characterizations via high-resolution transition electron microscope and X-ray photoelectron spectroscopy depth profiles reveal that parasitic reactions promote more Ni reduction and O deficiency and even rock-salt phase transformation at the surface of cathode materials. Our observation suggests that surface reconstructions have a strong affiliation to parasitic reactions that create chemically acidic environment to etch away the lattice oxygen and offer the electrical charge to reduce the valence state of transition metal. Thus, this study advances our understanding on surface reconstructions of Nirich cathodes and prepares us for searching for rational strategies.
基金supported by the Zhejiang Provincial Natural Science Foundation of China(Grant No.LY22F040001)the National Natural Science Foundation of China(Grant No.62071160)the Graduate Scientific Research Foundation of Hangzhou Dianzi University。
文摘The steep sub-threshold swing of a tunneling field-effect transistor(TFET)makes it one of the best candidates for lowpower nanometer devices.However,the low driving capability of TFETs prevents their application in integrated circuits.In this study,an innovative gate-all-around(GAA)TFET,which represents a negative capacitance GAA gate-to-source overlap TFET(NCGAA-SOL-TFET),is proposed to increase the driving current.The proposed NCGAA-SOL-TFET is developed based on technology computer-aided design(TCAD)simulations.The proposed structure can solve the problem of the insufficient driving capability of conventional TFETs and is suitable for sub-3-nm nodes.In addition,due to the negative capacitance effect,the surface potential of the channel can be amplified,thus enhancing the driving current.The gateto-source overlap(SOL)technique is used for the first time in an NCGAA-TFET to increase the band-to-band tunneling rate and tunneling area at the silicon-germanium heterojunction.By optimizing the design of the proposed structure via adjusting the SOL length and the ferroelectric layer thickness,a sufficiently large on-state current of 17.20μA can be achieved and the threshold voltage can be reduced to 0.31 V with a sub-threshold swing of 44.98 mV/decade.Finally,the proposed NCGAA-SOL-TFET can overcome the Boltzmann limit-related problem,achieving a driving current that is comparable to that of the traditional complementary metal-oxide semiconductor devices.
文摘The magnetic field generated in the air gap of the cage asynchronous machine and the harmonics of the magnetomotive forces creating that magnetic field,as well as the synchronous parasitic torques,radial magnetic forces have been discussed in great detail in the literature,but always separately,for a long time.However,systematization of the phenomenon still awaits.Therefore,it is worth summarizing the completeness of the phenomena in a single study–with a new approach at the same time-in order to reveal the relationships between them.The role of rotor slot number is emphasized much more than before.New formulas derived for both synchronous torques and radial magnetic forces are used for further investigation.It will be shown that both phenomena in subject must be treated together.Formulas will be provided to take into account attenuation.Design guide will be provided to avoid dangerous rotor slot numbers.It will be shown that the generation of synchronous torques and radial magnetic forces do not depend–in this new approach-on the slot combination,but on the rotor slot number itself.
文摘The magnetic field generated in the air gap of the cage asynchronous machine and the harmonics of the magnetomotive forces creating that magnetic field, as well as the related differential leakage, attenuation, asynchronous parasitic torques have been discussed in great detail in the literature, but always separately, for a long time. However, systematization of the phenomenon still awaits. Therefore, it is worth summarizing the completeness of the phenomena in a single study – with a new approach at the same time-in order to reveal the relationships between them. The role of rotor slot number is emphasized much more than before. An existing, commonly used, but still impractical basic figure has been modified to more clearly demonstrate the response of the rotor for the harmonics of the stator. The need to treat differential leakage, asynchronous parasitic torques and attenuation together will be demonstrated: new formula for asynchronous parasitic torque is derived;the long-used characteristic curves for differential leakage and attenuation used separately so far was merged into one, correct curve in order to provide a correct design guide for the engineers.
基金supported by the National Natural Science Foundation of China(Nos.61574167,51407181)
文摘Sensitivity analysis methods help to deal with the challenges of process variation in extraction of parasitic capacitances in an integrated circuit. The dual discrete geometric methods(DGMs), which have been recently utilized to extract parasitic capacitances, are reviewed. The computation method based on the dual DGMs for sensitivities of capacitances with respect to the given process parameters is presented. As the dual DGMs utilize scalar electric potential is unknown, the capacitances are obtained effectively, and then the sensitivities are calculated conveniently.