ELECTROCHEMICAL BEHAVIOR OF FERROIN IN IMPROVED PEO-LICLO_4 COMPLEX

Solid-state cyclic voltammetry was used to study electrochemical behavior of ferroin, which indicates that ferroin performs a reversible redox process in the improved PEO-LiClO_4 complex.An activation energy of ca.6.0 Kcal/mol for ferroin diffusion was evaluated from temperature dependence of diffusion coefficient.

Ce&F multifunctional modification improves the electrochemical performance of LiCoO_(2)at 4.60 V

Lithium cobalt oxide(LiCoO_(2))is proverbially employed as cathode materials of lithium-ion batteries attributed to the high theoretical capacity,and currently,it is developing towards higher cut-off voltages in the pursuit of higher energy density.However,it suffers from serious structural degradation and surface side reactions,in particular,at the voltage above 4.60 V,leading to rapid decay of the battery life.Taking into account the desirable oxygen buffering property and the fast ion mobility characteristic of cerium oxide fluoride,in this work,we prepared Ce&F co-modified LiCoO_(2)by using the precursors of Ce(NO_(3))_(3)·6H_(2)O and NH_(4)F,and evaluated the electrochemical performance under voltages exceeding 4.60 V.The results indicated that the modified samples have multiphase heterostructure of surface CeO_(2-x)and unique Ce-O-F solid solution phase.At 3.0–4.60 V and 25℃,the preferred sample LCO-0.5Ce-0.3F has a high initial discharge specific capacity of 221.9 mA h g^(-1)at 0.1 C,with the retention of 80.3%and 89.6%after 300 cycles at 1 and 5 C,comparing with the pristine LCO(56.4%and 22.6%).And at 3.0–4.65 V,its retention is 64.0%after 300 cycles at 1 C,versus 8.5%of the pristine LCO.Through structural characterizations and DFT calculations,it suggests that Ce^(4+)&F^(-)co-doping suppresses the H3 to H1/3 irreversible phase transition,stabilizes the lattice structure,and reduces the redox activity of the lattice oxygen by modulating the Co 3d–O 2p energy band,consequently improving the electrochemical performance of LiCoO_(2)at high voltages.

Microstructure and electrochemical corrosion behavior of selective laser melted Ti−6Al−4V alloy in simulated artificial saliva

Ti−6Al−4V alloy was fabricated via selective laser melting(SLM)to improve its corrosion resistance for implant.The microstructure and electrochemical corrosion behavior were investigated using scanning electron microscopy(SEM),electron backscatter diffraction(EBSD),transmission electron microscopy(TEM),electrochemical test and contact angle test.It can be found that the as-selective laser melted(as-SLMed)Ti−6Al−4V alloys showβcolumnar microstructure in building direction and nearly circular checkerboard microstructure in scanning direction,while the wrought and wrought+HT samples exhibit equiaxed microstructure.The as-SLMed Ti−6Al−4V alloy exhibits better corrosion resistance than the wrought and wrought+HT samples due to hydrophobicity,high grain boundary density and uniform distribution of alloying elements in simulated artificial saliva at 37℃.

Li_(2)CrO_(4)缓蚀剂对镁电池负极耐蚀性及电化学性能的改善

针对AZ31镁合金作为镁电池负极时存在自腐蚀速率大、阳极极化、电位滞后等问题,寻找合适的缓蚀剂及其用量调配电解液以提高电池的放电性能。通过腐蚀浸泡试验表征了缓蚀剂Li_(2)CrO_(4)的缓蚀效果,然后通过极化曲线、电化学阻抗谱研究了Mg(ClO_(4))_(2)溶液中Li_(2)CrO_(4)用量对AZ31镁合金电化学性能的影响,最后通过组装水系镁锰电池进行恒流放电作为应用端测试。结果表明:Li_(2)CrO_(4)能够使AZ31镁合金的腐蚀电位正移,最大正移量达到150 m V,在水系镁锰电池应用中能够提高镁电池的放电平台,当Li_(2)CrO_(4)质量分数为0.7%时放电平台提高0.15 V左右;当Li_(2)CrO_(4)质量分数为1.2%时,其能够显著改善AZ31镁合金在Mg(ClO_(4))_(2)溶液中的腐蚀,水系镁锰电池放电容量达最大,为196.9 m A·h,相对空白溶液,电池的放电容量提高约64%,工作电压高达1.39 V且放电曲线稳定。

硫化碱溶液中 SnS_4^(4-)阴极还原的电化学行为

本文用稳态法研究了硫化碱溶液中 SnS_4^(4-)在锡电极上还原的电化学行为.测定了 Na_2S、NaoH、As^(3+)、SnS_4^(4-)浓度和温度等对 SnS_4^(4-)析出的影响.

Studies on polyoxymethylene dimethyl ethers production from dimethoxymethane and 1,3,5-trioxane over SO_(4)^(2-)/ZrO_(2)-TiO_(2)

Polyoxymethylene dimethyl ethers(OMEs)with physical properties similar to those of diesel has received significant attention as green additives for soot emission suppression.Herein,series of SO_(4)^(2-)/ZrO_(2)-TiO_(2)catalysts were developed for OMEs production from dimethoxymethane(DMM)and1,3,5-trioxane through sequential formaldehyde monomer insertion into C-O bond of DMM.Not Lewis but Bronsted acid sites were identified to be active for the decomposition of 1,3,5-trioxane into formaldehyde unit,however,both of them are effective for the chain propagation of DMM via formaldehyde unit insertion into C-O bond.Kinetic studies indicated each chain growth step exhibited the same parameters and activation barrier on corresponding Bronsted and Lewis acid sites due to the same reaction mechanism and very similar chemical structure of OMEs.Also,the catalytic stability investigation suggested the deactivation behavior was derived from the carbon deposition,and the decay factor could be exponentially correlated with the amount of coke accumulation.

Electrochemical dissolution and passivation of laser additive manufactured Ti6Al4V controlled by elements segregation and phases distribution

The electrochemical dissolution and passivation of laser additive manufactured Ti6Al4V were investigated through Tafel polarization,potentiostatic polarization and AC impedance measurements.The results show that the solution treatment−aging(STA)process aggravates the element micro-segregation compared to the annealing process,leading to varied Al and V contents of the phases from different samples.It is proven that either Al-rich or V-rich condition can highly affect the electrochemical dissolution behaviors due to thermodynamical instability caused by element segregation.The dissolution rate in the metastable passivation process is controlled by the stability of the produced film that is affected by phases distribution,especially the difficult-to-dissolve phase.And then,the dissolution rate of the phases in the transpassivation region is consistent with the rank in the activation process because the dense film is not capable of being produced.Compared to the annealed sample,the higher dissolution rate of the STA sample is beneficial to the electrochemical machining(ECM)of Ti6Al4V.

Synthesis,Crystal Structure and Thermal Behavior of 4,5-Dimethoxy-2-(dinitromethylene)imidazolidine

A new energetic material,4,5-dimethoxy-2-（dinitromethylene）imidazolidine（DMDNI）,was synthesized by the reaction of 4,5-dihydroxyl-2-（dinitromethylene）-imidazolidine（DDNI） and methanol,and structurally characterized by single crystal X-ray diffraction.DMDNI crystallized in triclinic space group P1,with crystal data a=0.4324（4） nm,b=1.3599（11） nm,c=1.7503（14） nm,α=77.406（14）°,β=84.494（15）°,γ=87.976（14）°,V=0.9997（14） nm 3,Z=4,μ=0.140 mm-1,F（000）=488,D c =1.556 g/cm ^3,R 1 =0.0773 and wR 2 =0.1574.Thermal decomposition of DMDNI was studied,and its thermal decomposition process was divided into two stages.The first stage was a melting process and the second stage was an exothermic decomposition process.The enthalpy,apparent activation energy and pre-exponential constant of the exothermic decomposition reaction are-491.5 J/g,142.3 kJ/mol and 10 14.24 s^-1,respectively.The critical temperature of thermal explosion is 162.47 °C.DMDNI has a lower thermal stability than DDNI but it is close to that of 4,5-diacetoxyl-2-（dinitromethylene）-imidazolidine（DADNI）.

4′,7-二甲氧基-3′-异黄酮磺酸钠的电化学行为研究

采用线性扫描伏安法和循环伏安法研究了 4′ ,7 二甲氧基 3′ 异磺酮磺酸钠 (Sodium 4′ ,7 dimethoxy 3′ isoflavonesulfonate ,SDIS)在pH =1.0～ 12 .0的水溶液中的电化学行为 .实验结果表明 :在pH =1.0～ 5 .0条件下所获得的Pc1 ,Pc2 波分别为SDIS的单质子单电子不可逆还原波及还原中间体自由基的单电子单质子不可逆还原波 ;在 5 <pH <8条件下所获得的Pc1 波 ,仍属于SDIS单电子单质子不可逆还原波 ,而还原中间体自由基的单电子波被氢波掩盖 ;在pH >8.0的 0 .2mol·L-1 Britton Robinson缓冲溶液中所获得的Pc1 ,Pc2

杯[4]芳烃四磺酸的合成及电化学行为

以杯[4]芳烃和浓硫酸为原料,合成了杯[4]芳烃四磺酸,即5,11,17,23-四磺酸基-25,26,27,28-四羟基杯[4]芳烃,对其进行紫外可见和热重与差热分析（TG-DTA）,同时以KH2PO4-Na2HPO4为缓冲溶液,研究5,11,17,23-四磺酸基-25,26,27,28-四羟基杯[4]芳烃电化学行为。实验结果表明,当扫描电位在-1.2~0.8V时,有一不可逆的还原峰,还原峰电位在0.93V左右,且还原峰电位因扫描速度的改变而改变。

对磺酸基苯偶氮杯[4]芳烃电化学行为研究

以杯[4]芳烃和对氨基苯磺酸为原料,经重氮化-偶联反应合成了对磺酸基苯偶氮杯[4]芳烃,并使用紫外吸收光谱、红外吸收光谱、核磁共振等技术对其进行表征分析.首次以CH_3COOH-CH_3COONa为缓冲溶液,使用循环伏安法研究对磺酸基苯偶氮杯[4]芳烃的电化学行为.结果表明,当扫描电位在-0.5~1 V时,有1对氧化还原峰,其中氧化峰电位为0.302 V,还原峰电位为-0.003 V,且峰电流与峰电位均与扫描速率呈线性关系,推测该峰的形成受扩散控制影响,反应为动力学准一级可逆反应.进一步利用多种电化学手段研究该电极反应,并求得动力学参数,反应活化能为14.84 k J·mol^(-1).

Fe_3O_4 Magnetic Nanoparticles Modified Electrode as a Sensor for Determination of Nimesulide

A novel type of Fe3O4 nanoparticles modified glass carbon electrode（Fe3O4/GCE） was constructed and the electrochemical properties of N-（4-nitro-2-phenoxyphenyl）methanesulfonamide（nimesulide） were studied on the Fe3O4/GCE.In 0.4mol/L HAc-NaAc buffer solution（pH=5.0）,the electrode process of nimesulide was irreversible at bare GCE and Fe3O4/GCE.The Fe3O4/GCE exhibited a remarkable catalytic and enhancement effect on the reduction of nimesulide.The reduction peak potential of nimesulide shifted positively from-0.683 V at bare GCE to-0.625 V at Fe3O4/GCE,and the sensitivity was increased by ca.3 times.Some experimental conditions were optimized.The linear range between the peak current and the concentration of nimesulide was 2.6×10-6 ＂1.0×10-4mol/L（R=0.993） with a detection limit of 1.3×10-7mol/L.This method has been used to determine the content of nimesulide in medical tablets.The recovery was determined to be 96.9% ＂101.9% by means of standard addition method.The method is comparable to UV-Vis spectrometry.

Curing Behaviors and Thermal Properties of Dimer Fatty Acid （DFA） Modified Multifunctional Epoxy Resin

In order to improve the toughness of the cured aromatic tetrafunctional epoxy resins, a dlmer rarboxylic acid named dlmer fatty acid （DFA） was used to modify an aromatic tetrafunctional epoxy, N, N, N＇, N＇-tetraglycidyl-2,2-bis [ 4-（ 4-aminophcuoxy ） phenyl ] propane （TGBAPP）. The curing behaviors of DFA- TGBAPP/MNA （ methyl nadic anhydride） systems were studied by differential scanning calorimetry （DSC） method. And the thermal properties of the cured epoxy resin were investigated with the thermo-gravimetric analysis （TGA） and dynamic mechanical analysis （DMA）. Besides, the toughness was characterized with the impact strength tested by charpy impact testing. The results indicated that the modification would improve the curing reactions, and the curing temperatures were decreased with the increasing content of DFA. The thermal properties were not influenced obviously, and the toughness could be improved when the epoxy resin was modified with DFA.

AVP(4-8) Improves Cognitive Behaviors and Hippocampal Synaptic Plasticity in the APP/PS1 Mouse Model of Alzheimer’s Disease

Memory deficits with aging are related to the neurodegeneration in the brain, including a reduction in arginine vasopressin(AVP) in the brain of patients with Alzheimer’s disease(AD). AVP(4-8), different from its precursor AVP, plays memory enhancement roles in the CNS without peripheral side-effects. However, it is not clear whether AVP(4-8) can improve cognitive behaviors and synaptic plasticity in the APP/PS1 mouse model of AD. Here, we investigated for the first time the neuroprotective effects of AVP(4-8) on memory behaviors and in vivo long-term potentiation(LTP) in APP/PS1-AD mice.The results showed that:(1) APP/PS1-AD mice had lower spontaneous alternation in the Y-maze than wild-type(WT) mice, and this was significantly reversed by AVP(4-8);(2) the prolonged escape latency of APP/PS1-AD mice in the Morris water maze was significantly decreased by AVP(4-8), and the decreased swimming time in target quadrant recovered significantly after AVP(4-8) treatment;(3) in vivo hippocampal LTP induced by high-frequency stimulation had a significant deficit in the AD mice, and this was partly rescued by AVP(4-8);(4) AVP(4-8)significantly up-regulated the expression levels of postsynaptic density 95(PSD95) and nerve growth factor(NGF)in the hippocampus of AD mice. These results reveal the beneficial effects of AVP(4-8) in APP/PS1-AD mice,showing that the intranasal administration of AVP(4-8)effectively improved the working memory and long-term spatial memory of APP/PS1-AD mice, which may be associated with the elevation of PSD95 and NGF levels in the brain and the maintenance of hippocampal synaptic plasticity.

Effect of VO4^3- Substitution on the Electrochemical Properties of a LiSn2（PO4）3 Anode Material

VO4^3- anion was used to partially substitute for PO43 in the Nasicon compound of LiSn2（PO4）3 via a sol-gel method. XRD analysis revealed that the VO4^3-substituted samples did not have a single LiSn2（PO4）3 phase, and some secondary phases like SnO2 and SnP2O7 appeared. Introduction of the VO4^3- anion did not prevent the LiSn2（PO4）3 compound from decomposing during the initial lithiation; however the VO4^3- anion substitution remarkably enhanced the rate capability and cycling performance of the products because they reduced the charge transfer hnpedance, increased the lithium ion diffusion, and strengthened the role of the Li3PQ matrix due to the precipitation of the Li3V04 phase, Of the substituted samples, the sample with a nominal composition of LiSn2（PO4）2.5（VO4）0.5 delivered a capacity of 449.2 mA-h/g at a rate of 0.25 C after 25 cycles and 373.8 mA.h/g at 2 C rate. Those values surpassed some previous reports on LiSn2（PO4）3 and the LiSnz（PO4）3/C composites. Accordingly, the partial substitution of phosphorus by vanadium in LiSn2（PO4）3 is a feasible technique to remarkably improve its electrochemical properties.

Electrochemical Corrosion Behavior and Mechanical Response of Selective Laser Melted Porous Metallic Biomaterials

The porous metallic biomaterials have attracted significant attention for implants because their lower young's modulus matches the human bones, which can eliminate the stress shielding effect and facilitate the growth of bone tissue cells. The porous metallic biomaterials fabricated by selective laser melting (SLM) have broad prospects, but the surface of the SLM-built porous structure has been severely adhered with unmelted powders, which affects the forming accuracy and surface quality. The porous metallic biomaterials face the corrosion problem of complex body fluid environments during service, so their corrosion resistance in the human body is extremely important. The surface quality will affect the corrosion resistance of the porous metallic biomaterials. Therefore, it is necessary to study the effect of post-treatment on the corrosion resistance of SLMed samples. In this work, the mechanical response and the electrochemical corrosion behavior in simulated body fluid of diamond and pentamode metamaterials Ti-6Al-4V alloy fabricated by SLM before and after sandblasting were studied. After sandblasting, the mechanical properties of the two porous metallic biomaterials were slightly improved, and the self-corrosion potential and pitting potential were more negative;meanwhile, the self-corrosion current density and passive current density increased, indicating that its corrosion performance decreased, and the passive film stability of sandblasted samples got worse.

Corrosion behavior of hafnium in anhydrous isopropanol and acetonitrile solutions containing bromide ions

The corrosion behaviors of hafnium in Et4NBr isopropanol and acetonitrile(ACN)solutions were investigated usingelectrochemical measurements,ICP-AES and SEM techniques.Results revealed that the open circuit potential gets more positive dueto the increased passivity of the surface oxide film with increasing immersion time until it reaches a steady state value.Thepotentiodynamic anodic polarization curves did not exhibit an active dissolution region near corrosion potential due to the presenceof an oxide film on the electrode surface,which was followed by pitting corrosion.SEM images confirmed the existence of pits onthe electrode surface.Cyclic voltammetry and galvanostatic measurements allowed the pitting potential(φpit)and the repassivationpotential(φp)to be determined.φpit increased with increasing potential scanning rate but decreased with increasing temperature,Br-concentration and ACN concentration.The impedance spectra showed that the resistances of the solution and charge transferdecreased with the increase of ACN concentration.

Studies on 3-Amino-4-(1H-tetrazol-5-yl)-furazan:Crystal Structure, Thermal Behavior and Energetic Performance

The structure of 4-amino-3-(5-tetrazolate)-fiirazan(HAFT) was characterized by single crystal X-ray diffraction. The thermal decomposition process of HAFT was investigated by MS-FTIR-DSC-TG coupling technique. The result shows that the exothermic process occurs from 278.7-350℃, with a peak temperature of 324.7℃. The thennal decomposition gaseous products of HAFT are NO2, CO2, HCN, CO, NH3 and H2O. The detonation velocity and detonation pressure of HAFT were calculated by the nitrogen equivalent equation. The detonation velocity of HAFT is 7727.46 m/s, which is higher than that of TNT(7178 m/s). The detonation pressure of HAFT(25.27 GPa) is satisfactory. The sensitivity tests reveal HAFT possesses excellent insensitivities to impact and friction.

（4-Ferrocenylethyne） phenylamine on Graphene as the Signal Amplificator to Determinate Dopamine and Acetaminophen Simultaneously

A novel （4-ferrocenylethyne） phenylamine functionalized graphene sheets （FEPA-GR）, coupling with chitosan （CS） were used as a signal amplification platform for simultaneous and sensitive determination of dopamine （DA） and acetaminophen （AC）. In this work, FEPA used as electron transfer mediator can be immobilized on GR surface via strong π-π stacking interaction between the conjugate chain of FEPA and GR, which effectively prevents FEPA electron mediator leaking from the electrode surface and amplified the signal. Transmission electron microscopy, FT-IR spectroscopy, UV-vis spectroscopy and electrochemical experiments results are all demonstrated the strong π-π stacking interaction between FEPA and GR. The resulted biosensor exhibited a fast response, remarkable electrocatalytic activity, perfect anti-interference ability and good stability for simultaneous detection of DA and AC. Under the optimum conditions, the oxidation peak currents of DA and AC were linearly correlated to their concentrations in the range of 2.0-135.0 μmol·L-1 and 0.3--80.0μmol·L 1, respectively. The lower detection limits for DA and AC were 0.30 and 0.05 μmol·L-1, respectively. The feasibility of the proposed method was validated by successfully applied to the simultaneous determination of DA and AC in serum samples with the standard addition method.

水中苯酚的循环伏安法行为研究和浓度检测

利用循环伏安法研究4-氨基安替比林(4-app)直接分光光度法测试苯酚的实验体系的电化学性能,阐明4-app分光光度法测定苯酚的反应机理。利用裸玻碳电极分析苯酚与4-app在缓冲溶液中的循环伏安行为,获得氧化峰电流与苯酚浓度之间的线性关系,提出一种新的检测苯酚浓度的方法。实验结果显示:在4-app/缓冲溶液中9.25×10^-8~9.25×10^-6 mol/L的苯酚与氧化峰电流具有良好的线性关系,相关系数R2=0.9964,检测限为3.7×10^-9 mol/L。