Reversed charge transfer induced by nickel in Fe-Ni/Mo_(2)C@nitrogen-doped carbon nanobox for promoted reversible oxygen electrocatalysis

The interaction between metal and support is critical in oxygen catalysis as it governs the charge transfer between these two entities,influences the electronic structures of the supported metal,affects the adsorption energies of reaction intermediates,and ultimately impacts the catalytic performance.In this study,we discovered a unique charge transfer reversal phenomenon in a metal/carbon nanohybrid system.Specifically,electrons were transferred from the metal-based species to N-doped carbon,while the carbon support reciprocally donated electrons to the metal domain upon the introduction of nickel.This led to the exceptional electrocatalytic performances of the resulting Ni-Fe/Mo_(2)C@nitrogen-doped carbon catalyst,with a half-wave potential of 0.91 V towards oxygen reduction reaction(ORR)and a low overpotential of 290 m V at 10 mA cm^(-2)towards oxygen evolution reaction(OER)under alkaline conditions.Additionally,the Fe-Ni/Mo_(2)C@carbon heterojunction catalyst demonstrated high specific capacity(794 mA h g_(Zn)~(-1))and excellent cycling stability(200 h)in a Zn-air battery.Theoretical calculations revealed that Mo_(2)C effectively inhibited charge transfer from Fe to the support,while secondary doping of Ni induced a charge transfer reversal,resulting in electron accumulation in the Fe-Ni alloy region.This local electronic structure modulation significantly reduced energy barriers in the oxygen catalysis process,enhancing the catalytic efficiency of both ORR and OER.Consequently,our findings underscore the potential of manipulating charge transfer reversal between the metal and support as a promising strategy for developing highly-active and durable bi-functional oxygen electrodes.

A novel 4H-SiC trench MOSFET with double shielding structures and ultralow gate-drain charge

A new ultralow gate–drain charge(Q_(GD)) 4 H-SiC trench MOSFET is presented and its mechanism is investigated by simulation. The novel MOSFET features double shielding structures(DS-MOS): one is the grounded split gate(SG), the other is the P+shielding region(PSR). Both the SG and the PSR reduce the coupling effect between the gate and the drain, and transform the most part of the gate–drain capacitance(C_(GD)) into the gate–source capacitance(C_(GS)) and drain–source capacitance(C_(DS)) in series.Thus the C_(GD) is reduced and the proposed DS-MOS obtains ultralow Q_(GD). Compared with the double-trench MOSFET(DT-MOS)and the conventional trench MOSFET(CT-MOS), the proposed DS-MOS decreases the Q_(GD) by 85% and 81%, respectively.Moreover, the figure of merit(FOM), defined as the product of specific on-resistance(R_(on, sp)) and Q_(GD)(R_(on, sp)Q_(GD)), is reduced by 84% and 81%, respectively.

Synthesis and characterization of Ca2Sn1-xCexO4 with blue luminescence originating from Ce^4＋ charge transfer transition

Ce^4＋-doped Ca2SnO4 with a one-dimensional structure, which emits bright blue light, is prepared by using a solid-state reaction method. The x-ray diffraction results show that the Ce^4＋ ions doped in Ca2SnO4 occupy the Sn^4＋ sites. The excitation and emission spectra of Ca2Sn1-xCexO4 appear to have broad bands with peaks at - 268nm and -442nm, respectively. A long excited-state lifetime （-83μs） for the emission from Ca2Sn1-xCexO4 suggests that the luminescence originates from a ligand-to-metal Ce^4＋ charge transfer （CT）. The luminescent properties of Ca2Snl_xCexO4 have been compared with those of Sr2CeO4, which is the only material reported so far to show Ce^4＋ CT luminescence. More interestingly, it is observed that the emission intensity of Ca2Sn1-xCexO4 with a small doping concentration （x - 0.03） is comparable to that of Sr2CeO4 in which the concentration of active centre is 100%.

A novel single event upset reversal in 40-nm bulk CMOS 6T SRAM cells

In advanced technologies, single event upset reversal(SEUR) due to charge sharing can make the upset state of SRAM cells recover to their initial state, which can reduce the soft error for SRAMs in radiation environments. By using the full 3D TCAD simulations, this paper presents a new kind of SEUR triggered by the charge collection of the Off-PMOS and the delayed charge collection of the On-NMOS in commercial 40-nm 6 T SRAM cells. The simulation results show that the proposed SEUR can not occur at normal incidence,but can present easily at angular incidence. It is also found that the width of SET induced by this SEUR remains the same after linear energy transfer(LET) increases to a certain value. In addition, through analyzing the effect of the spacing, the adjacent transistors, the drain area, and some other dependent parameters on this new kind of SEUR, some methods are proposed to strengthen the recovery ability of SRAM cells.

Differential interformational velocity analysis as an effective direct hydrocarbon indicator under velocity reversal conditions,an example from the anomalously high temperature and over-pressured DF1-1 Gas Field in the Yinggehai Basin,South China Sea

In the DF1-1 Gas Field in the Yinggehai Basin, South China Sea, the velocity-depth plot and velocity spectra show significant variations from a linear trend, exhibiting a distinct reversal phenomenon. Velocity parameters derived from velocity spectral analysis of the seismic data and sonic logs indicate that the interval velocity reverses below 2,100 m (2.2 s two-way time (TWT)) in the DF1-1 Gas Field. Some direct hydrocarbon indicators (DHIs) models developed for the shallow strata cannot be simply applied to the moderately to deeply buried strata for direct exploration target recognition because the velocity reversal has caused the middle-deep gas reservoirs to exhibit a moderate or weak seismic amplitude. The hydrocarbon indicator method of “Differential Interformational Velocity Analysis (DIVA)” with the aid of other hydrocarbon indicating techniques was employed to effectively identify DHIs in the middle-deep strata under velocity inversion. The result has shown that the DIVA technique can be effectively used as a DHI in both the shallow and the middle-deep strata in the study area with the shallow strata characterized by Type I DIVA anomaly and the middle-deep strata characterized by the Type II DIVA anomaly.

Charge Transfer Properties in MEH-PPV/PS:MWCNTs Nanocomposites

The effect of composition and annealing temperature on charge transfer properties, in a donor/acceptor nanocomposites based on poly (2-methoxy-5-(2-ethyhexyl-oxy)-p-phenylenevinylene) (MEH-PPV) and MWCNTs functionalized with Polystyrene (PS:MWCNTs), have been investigated. The quenching of photoluminescence (PL) intensity of pure MEH-PPV, by adding different amounts of functionalized carbon nanotubes, exhibits that a photoinduced charge transfer has been occurred. Charge transfer efficiency was obtained for an acceptable concentration of PS:MWCNTs about 0.5 wt% and at annealed temperature of about 80℃. Quenching efficiency studies imply that MEH-PPV/PS:MWCNTs nanocomposites reveal a high degree of PL quenching, reaching a value of η = 76.9%.

Thermodynamics of charged black holes in Maxwell-dilaton-massive gravity

Considering the nonminimal coupling of the dilaton field to the massive graviton field in Maxwelldilaton-massive gravity,we obtain a class of analytical solutions of charged black holes,which are neither asymptotically flat nor(A)dS.The calculated thermodynamic quantities,such as mass,temperature,and entropy,verify the validity of the first law of black hole thermodynamics.Moreover,we further investigate the critical behaviors of these black holes in the grand canonical and canonical ensembles and find a novel critical phenomenon never before observed,known as the"reverse"reentrant phase transition with a tricritical point.It implies that the system undergoes a novel"SBH-LBH-SBH"phase transition process and is the reverse of the"LBH-SBH-LBH"process observed in reentrant phase transitions.

Micro- and nanoporous materials capable of absorbing solvents and oils reversibly： the state of the art

Treatment of petroleum spills and organic solvent pollution in general is an important issue; several techniques are under development to remove oil from water. The use of absorbents is one of the most common techniques to tackle this problem. These absorbents can be classified based on their characteristics of recyclability into irreversible and reversible ones. In this review, we discuss the application of several materials as oil absorbents, according to their classification and characteristics such as hydrophobicity, surface area and oil absorption capacity. Also, the fabrication methods for some materials are presented and analyzed.

Neuroprotective effects of human telomerase reverse transcriptase on beta-amyloid fragment 25-35-treated human embryonic cortical neurons

BACKGROUND： Numerous current studies have suggested that human telomerase reverse transcriptase （hTERT） gene has neuroprotective effects and can inhibit apoptosis induced by various cytotoxic stresses; however, the mechanism of action remains unknown. OBJECTIVE： To evaluate the neuroprotective effects and possible mechanism of action of hTERT gene transfection in human embryonic cortical neurons treated with beta-amyloid fragment 25-35 （AI325-35）. DESIGN, TIME AND SETTING： The randomized, controlled and molecular biological studies were performed at the Department of Anatomy and Brain Research, Zhongshan School of Medicine, Sun Yat-sen University, China, from September 2005 to June 2008. MATERIALS： AdEasy-1 Expression System was gifted by Professor Guoquan Gao from Sun Yat-Sen University, China. Human cortical neurons were derived from 12-20 week old aborted fetuses, obtained from the Guangzhou Maternal and Child Health Hospital, China. Mouse anti-Odk5 and mouse anti-p16 monoclonal antibodies （Lab Vision, USA）, and mouse anti-hTERT monoclonal antibody （Epitomics, USA）, were used in this study. METHODS： （1） Recombinant adenovirus vectors, encoding hTERT （Ad-hTERT） and green fluorescent protein （Ad-GFP）, were constructed using the AdEasy-1 Expression System. Human embryonic cortical neurons in the Ad-hTERT group were transfected with Ad-hTERT for 1-21 days. Likewise, human embryonic cortical neurons in the Ad-GFP group were transfected with Ad-GFP for 1-21 days. Human embryonic cortical neurons in the control group were cultured as normal. （2） Human embryonic cortical neurons in the Ad-hTERT group were treated with 10 pmol/L Aβ25-35 for 24 hours. Normal human embryonic cortical neurons treated with 10 pmol/Lβ25.35 for 24 hours served as a model group. Human embryonic cortical neurons in the Ad-GFP and control groups were not treated with Aβ25-35. MAIN OUTCOME MEASURES： Expression of hTERT in human embryonic cortical neurons was evaluated by immunocytochemical staining and Western blot assay. Telomerase activity was measured using a PCR-based telomeric repeat amplification protocol （TRAP） ELISA kit. Neural activity in human embryonic cortical neurons was examined by MTT assay; apoptosis was measured using TUNEL assay; and Cdk5 and p16 protein expressions were measured by Western blot. RESULTS： Expression of hTERT protein was significantly increased and peaked at day 3 post-transfection in the Ad-hTERT group. No hTERT expression was detected in the Ad-GFP and control groups. Telomerase activity was significantly greater in the Ad-hTERT group compared with the Ad-GFP and control groups （P 〈 0.01）. Compared with the control group, cell activity was significantly decreased （P 〈 0.05）, and cell apoptotic rate, Cdk5 and p16 expression were significantly increased （P 〈 0.01） in the model group. Compared with the model group, cell activity was increased in the Ad-hTERT group, and peaked at day 3 post-transfection （P 〈 0.05）. Neuroprotective effects also peaked at day 3 post-transfection; and the apoptotic rate, Cdk5 and p16 expression significantly decreased （P 〈 0.01）. CONCLUSION： Expression of hTERT in human embryonic cortical neurons can relieve Aβ25-35-induced neuronal apoptosis. The possible mechanism by which hTERT produces these neuroprotective effects may be associated with inhibition of Cdk5 and p16 expression.

基于M-W极化模型的低电场极性反转下XLPE/硅橡胶空间电荷与电场分布特性研究

相比于单一介质的电缆绝缘,高压直流电缆附件复合绝缘因介质不连续性更易在界面处积聚空间电荷。在基于电网换相器的高压直流(LCC-HVDC)输电系统中,进行潮流反转调整时需改变电压极性,高压直流电缆附件将会承受极性反转电场,尽管是短时的,但由于空间电荷的累积效应也会在局部产生极高的电场,严重影响绝缘性能。为此,该文利用实验获得交联聚乙烯(XLPE)与硅橡胶(SR)电导率与电场强度的变化关系,基于Maxwell-Wagner(M-W)极化模型仿真研究了低电场极性反转下XLPE/SR双层介质中空间电荷与电场的分布特性。结果表明:室温下,SR的低电场电导率要高于XLPE,且SR电导率受电场强度的影响相对较小而XLPE则较大。由于界面电荷极性变化滞后于电压极性变化,极性反转期间界面处残留的负极性电荷造成SR中出现最大瞬态电场;电压极性反转越快,XLPE/SR界面残留的负极性电荷越多,SR中的最大瞬态电场强度越高;外施电压越高,由于SR与XLPE的电导率比值降低,SR中的最大瞬态电场畸变率越小。

Preparation and Characterization of Cathode Materials La_(0.7)Sr_(0.3-x)Ca_xCo_(0.9)Fe_(0.1)O_(3-δ) by Reverse Titration Co-Precipitation Method for ITSOFC

The precursors of La0.7Sr0.3-xCaxCo0.9Fe0.1O3-δ(LSCCF, x=0.05, 0.10, 0.15, 0.20) as the cathode materials for intermediate temperature solid oxide fuel cell (ITSOFC) were prepared by reverse titration co-precipitation method with metal-nitrates as starting materials and mixed alkali (NaOH and Na2CO3) as a precipitating agent. The formation process of LSCCF from the precursors was monitored by TG-DSC, and the crystal structure and particles morphology of the precursors which were calcined at 600, 800, 1000 ℃ for 3 h were characterized using XRD, SEM technologies. Compared with the solid state reaction of constituent oxides, when the pH value of the precipitating solution was in the range of 9.1～9.5, the LSCCF powders from the precursors caclined at 800 ℃ for 3 h had high purity, homogeneous and single perovskite phase. The electrical conductivity of the LSCCF samples sintered at 1200 ℃ for 3 h, which was measured as a function of temperatures from 100 to 800 ℃ by DC four-probe method in air, decreased with x from 0.05 to 0.20. The value of electrical conductivity was almost equal because of Ca2+, Sr2+ co-dopant resulting in the 'mix effect' while x=0.10 or 0.15. The electrical conductivity of all doped samples was higher than 100 S·cm-1 at intermediate temperatures from 500 to 800 ℃, and there was good compatibility between the LSCCF cathode and Ce0.8Sm0.2O2 electrolyte.

DISRUPTION OF CHARGED DUST GRAINS IN COMETARY PLASMA ENVIRONMENTS

The equilibrium potential and dust fragmentation criterion of fluffy dust grains in plasma are calculated for comet P/Halley . It is found that the dust grain acquires its largest negative potential and disruptive probability about 50,000km from the comet where the dust mass spectrum measured by the spacecraft took a great change.

极性反转条件下基于双极性载流子-离子混合输运模型的XLPE空间电荷特性研究

直流电缆在运行时需承受极性反转的电压,这会使得绝缘内部积累的空间电荷增加,进而可能引起绝缘破坏。同时在绝缘材料实际生产过程中引入的交联副产物等杂质解离产生的离子电荷会加剧电荷的积累。因此本文对传统双极性载流子输运模型进行改进,考虑杂质带电离子的影响,利用改进后的输运模型模拟交联聚乙烯(XLPE)内部空间电荷在电压极性反转期间的分布,研究极性反转时间和电场强度对电荷分布的影响机理。结果表明:在满足电压反转前后空间电荷分布基本呈镜像分布的基础上,引入离子电荷会增大两电极附近稳态时积聚的异极性电荷量;电压反转时间越长,两电极处的界面电荷峰值下降的越多,两电极附近的空间电荷变成相反极性的电荷量也越多,即反转完成时电荷分布更接近于反转稳定后的情况;在相同极性反转时间、不同电场强度下,电荷分布规律基本相同,场强越高,各处积累的电荷量越多。

Replay Attack and Defense of Electric Vehicle Charging on GB/T 27930-2015 Communication Protocol

The GB/T 27930-2015 protocol is the communication protocol between the non-vehicle-mounted charger and the battery management system (BMS) stipulated by the state. However, as the protocol adopts the way of broadcast communication and plaintext to transmit data, the data frame does not contain the source address and the destination address, making the Electric Vehicle (EV) vulnerable to replay attack in the charging process. In order to verify the security problems of the protocol, this paper uses 27,655 message data in the complete charging process provided by Shanghai Thaisen electric company, and analyzes these actual data frames one by one with the program written by C++. In order to enhance the security of the protocol, Rivest-Shamir-Adleman (RSA) digital signature and adding random numbers are proposed to resist replay attack. Under the experimental environment of Eclipse, the normal charging of electric vehicles, RSA digital signature and random number defense are simulated. Experimental results show that RSA digital signature cannot resist replay attack, and adding random numbers can effectively enhance the ability of EV to resist replay attack during charging.

Charge-reversal nanoparticles: novel targeted drug delivery carriers

Spurred by significant progress in materials chemistry and drug delivery, charge-reversal nanocarriers are being developed to deliver anticancer formulations in spatial-, temporal- and dosagecontrolled approaches. Charge-reversal nanoparticles can release their drug payload in response to specific stimuli that alter the charge on their surface. They can elude clearance from the circulation and be activated by protonation, enzymatic cleavage, or a molecular conformational change. In this review, we discuss the physiological basis for, and recent advances in the design of charge-reversal nanoparticles that are able to control drug biodistribution in response to specific stimuli, endogenous factors(changes in p H,redox gradients, or enzyme concentration) or exogenous factors(light or thermos-stimulation).

特高压晶闸管p^-层穿通和p^+层发射极结构设计

基于传统晶闸管单扩散p层杂质浓度分布很难协调阻断电压、通流能力、通态压降、反向恢复电荷和关断时间之间的矛盾,无法使特高压晶闸管的通流能力由4 000 A提高到4 500 A。对特高压晶闸管采用低浓度p-层穿透、高浓度p+层发射极结构设计进行了理论分析并进行了工艺实验,测试结果表明,特高压晶闸管在不损失阻断电压(≥8 500 V)前提下,芯片厚度减薄0.05 mm、通态压降下降0.11 V,反向恢复电荷、dV/dt耐量、di/dt耐量、关断时间等得到优化,研制了6英寸(1英寸=2.54 cm)4 500 A/8 500 V特高压晶闸管,并成功应用于±800 kV/7 200 MW特高压直流输电工程中。

第三方环境信息平台参与下供应商污染问题协同治理研究

本文探讨了第三方环境信息平台参与下,制造商与银行对供应商污染问题的协同治理。首先,通过构建演化博弈模型,分析制造商、供应商与银行在不同阶段的策略;其次,以平台提高制造商污染信息获取能力的程度为依据提出治理方案,并设计动态收费机制;最后,通过Matlab仿真检验治理方案与两种收费机制的治理效果。研究表明:(1)制造商污染信息获取能力是有效协同治理的前提;(2)在治理方案中,更高程度地提高制造商污染信息获取能力或者一定程度提高能力且加大订单激励的效果更好;(3)当制造商污染信息获取能力较强且供应商利润水平较低时,动态收费机制更有效。因此,政府应推进环境信息公开,为平台、制造商与银行的协作建立基础,进而多方形成合力共同治理供应商污染问题。

具有多晶阻挡层的浮空P区IGBT开关特性研究

为了减少浮空P区IGBT结构的栅极空穴积累,改善结构的电磁干扰(EMI)噪声问题,从而提高结构电磁干扰噪声与开启损耗(Eon)之间的折中关系,研究提出了一种具有多晶硅阻挡层的FD-IGBT结构。新结构在传统结构的浮空P区上方引入一块多晶硅阻挡层,阻挡层接栅极,形成与N型漂移区的电势差。新结构在器件开启过程中,多晶硅阻挡层下方会积累空穴,导致栅极附近积累的空穴数量减少,从而降低浮空P区对栅极的反向充电电流。通过TCAD软件仿真结果表明,相比于传统FD-IGBT,新结构开启瞬态的过冲电流(I_(CE))和过冲电压(V_(GE))的峰值分别下降26.5%和8.6%,且在栅极电阻(R_(g))增加时有更好的电流电压可控性;相同开启损耗下,新结构的dI_(CE)/dt、dV_(CE)/dt和dV_(KA)/dt最大值分别降低26.5%,15.1%和26.1%。

Efficient and Fast X-Ray Luminescence in Organic Phosphors Through High-Level Triplet-Singlet Reverse Intersystem Crossing

Organic scintillators that efficiently generate bright triplet excitons are of critical importance for highperformance X-ray-excited luminescence in radiation detection.However,the nature of triplet-singlet spinforbidden transitions in these materials often result in long-lived phosphorescence,which is undesirable for ultrafast X-ray detection and imaging.Here we demonstrate that the effect of hybridized local and charge-transfer(HLCT)excited states enables organic scintillators to exhibit highly efficient and fast radioluminescence(RL)in response to X-ray irradiation.Our experimental and theoretical investigation shows that the oxidized 1,8-naphthalimide-phenothiazine dyad(OMNI-PTZ 2)with HLCT-excited states has an enhanced overlap integral of the highest occupied molecular orbital(HOMO)and lowest unoccupied molecular orbital(LUMO)on MNIπ-orbitals,and moderate donor–acceptor electron interactions.As a result,the RL of these crystals exhibits a 61-fold increase and its monoexponential decay lifetime is three orders of magnitude faster compared to its corresponding thermally activated delayed fluorescence(TADF)molecule MNI-PTZ 1.We further demonstrate the practical utility of the OMNI-PTZ 2(G)in high-performance X-ray detection and imaging,achieving an X-ray dose sensitivity of 97 nGy s−1 and an exceptional spatial resolution of 20 lp/mm.Our study provides a promising molecular design principle for utilizing triplet excitons to develop high-efficiency and fast X-ray scintillators for the development of next-generation flexible and stretchable X-ray imaging detectors.

Hydrocarbon Charging and Accumulation Process of the Large Bozhong19-6 Condensate Gas Reservoirs in the Southwestern Bozhong Sub-Basin,Bohai Bay Basin,China

The Bozhong19-6(BZ19-6)condensate gas reservoirs,located in the southwestern Bozhong sub-basin,Bohai Bay Basin,China,were paleo-oil reservoirs in the geological past and have undergone at least three successive hydrocarbon charging events.The hydrocarbon migration and accumulation process of“early oil and late gas”has occurred in the current reservoirs.At the end of the sedimentation of the Guantao Formation(N_(1)g,∼12 Ma),the reservoirs began to fill with first stage low-moderate mature crude oil.At the late stage of the Lower Minghuazhen Formation(N_(1)ml)(∼6.7 Ma),the reservoirs were largely charged with second stage high mature crude oil.Since the deposition of the upper Minghuazhen Formation(N_(2)m^(u),∼5.1 Ma),the paleo-oil reservoirs were transformed into shallow Neogene reservoirs due to the reactivation of basement faults.From the late stage of the N_(2)m^(u)to the present day(∼2.8–0 Ma),the reservoirs were rapidly filled by natural gas within a short period.In addition,analysis of the formation of the reservoir bitumen and the conspicuous loss of the lower molecular weight n-alkanes in the crude oil reveal that the injection of a large amount of gas in the late stage caused gas flushing of the early charged oil.