有机可逆热致变色材料的变色机理及应用进展

有机可逆热致变色材料低温变色性能优于传统的无机可逆变色材料,已受到广泛的关注。目前,研究与开发的有机可逆热致变色材料已不少,其变色机理不尽相同。重点介绍了分子结构的变化对有机可逆热致变色材料变色机理的影响,并概述了有机可逆热致变色材料的应用。     

Scanning electrochemical microscopy. 46. Shielding effects on reversible and quasireversible reactions

An approximate theory for the feedback mode of the scanning electrochemical microscope (SECM) is developed to interpret the effects of substrate shielding on an ultramicroelectrode tip during a recording of iT versus d curves (approach curves) for reversible and quasireversible kinetics at a substrate surface. The resulting expressions for the tip current, iT, show a good fit to more accurate SECM simulations as well as to the experimental response of a reversible and quasireversible reaction. SECM shielding experiments thus give an interesting new insight into SECM approach curves over electrodes at different potentials, which suggest possible applications to measuring heterogeneous kinetics for fast reactions and diffusion coefficient determination.     

Square wave voltcoulometry: a tool for the study of strongly adsorbed redox molecules

A new multipotential pulse technique called square wave voltcoulometry (SWVC), based on the analysis of the difference of converted charge signals obtained between two successive half-cycles when a square wave potential is applied, is developed to study charge-transfer processes taking place in electroactive monolayers. The use of SWVC presents the advantage of giving rise to a peak-shaped response, which evolves to a charge plateau at high square wave pulse amplitudes, from which the total surface excess and the formal potential can be immediately measured for quasi-reversible and reversible processes. This characteristic represents its main advantage versus other multipotential step techniques, which lead to a negligible current under reversible conditions. The formal potential of the electroactive systems can be measured from the peak potential of the SWVC curves, even for quasi-reversible behavior. Moreover, the non-faradic effects on the response can be easily evaluated and avoided as is demonstrated in this paper. Experimental verification of the theoretical predictions is given for reversible and quasi-reversible systems.     

An analytical model for reversible radiation effects on polymer specific heat

A study is made of the energy balance in gas release by radiation in polymers as one of the possible mechanisms for reversible effects on the specific heat.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 46, No. 5, pp, 781–789, May, 1984.     

Surface plasmon resonance studies of gas effects in phthalocyanine Langmuir-Blodgett films

Surface plasmon resonance is a promising technique for the investigation of thin overlayers deposited onto metal films and consequently for use in sensing applications. The method has been used to investigate the interaction between nitrogen dioxide and Langmuir-Blodgett films of a tetra-4-tert- butylphthalocyanine containing silicon. A number of different effects have been observed in this preliminary study. These are (a) the irreversible growth of an optically absorping surface layer on the silver film, (b) a partially reversible change in the absorption spectrum of the phthalocyanine which has been attributed to chemical reaction, and (c) reversible effects due to adsorption and desorption of gas by the phthalocyanine film.     

Principles of identification of the physical processes caused by variation of thermodynamic parameters in solids

A method is proposed which permits identification of the reversible and irreversible thermodynamic processes occurring in solids as thermodynamic conditions vary, and definition of the contribution of each process to the whole. Theoretical values have been obtained of the ratio of the rates of change of enthalpy and volume as well as the ratio of the total heat and volume effects for a series of processes in solids. The method is applied to some actual special cases.     

Investigation of photo-induced effects in r.f.- sputtered a-Si

Using a gap cell geometry we investigated reversible photo-induced effects in r.f.-sputtered a-Si and found that these effects are dependent on the substrate material. In an attempt to interpret the electrical measurements, transmission electron microscopy studies were also undertaken.     

Transient modeling of the reversible response of the hydrogel to the change in the ionic strength of solutions

In this paper, a multi-effect-coupling ionic-strength-stimulus (MECis) model, which couples the mechanical, chemical and electrical effects on the swelling/shrinking of the smart hydrogel responsive to the ionic strength of the environmental solution, is presented for the transient analysis of the reversible kinetics of the ionic-strength-sensitive hydrogel. The MECis model is based on the laws of momentum and mass conservation, and considers the poroelasticity of the ionic-strength-sensitive hydrogel. In order to examine the model, the simulation results are compared with the experimental data with reversible swelling-shrinking kinetics, and they are in quite agreement. The reversible characteristics, including the mobile ions concentrations, the fixed charge density, the electric potential and the hydrogel displacement, are studied in order to fully understand the kinetics behavior of the ionic-strength-sensitive hydrogel.     

生物模板法合成酵母碳微球负极材料及其储钠性能研究

以酵母为生物模板和绿色碳源,分别在900℃、1100℃和1300℃条件下对其高温热解,获得了尺寸和形貌高度均匀的碳微球。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、氮气脱吸附仪对所得碳微球的物相组成、形貌、比表面积进行表征,并探讨了不同热解温度对其电化学性能的影响。结果表明,1100℃热解所得酵母碳材料展示出较高的可逆储钠比容量(205mAh/g,0.1C=20mA/g)和优异的循环稳定性(186mAh/g@100次)。采用生物模板法合成酵母碳微球的策略不仅可以实现生物材料绿色高效利用,同时也为钠离子电池提供了一种极具潜力的碳负极材料。     

Reversible coercivity vs. temperature losses in activated cobalt adsorbed iron oxides

Most properties of CrO2in magnetic recording media can be matched -and in some cases superseeded- by Surface-Cobalt Modified Iron Oxides. However, while the variation of coercivity with temperature for CrO2is a fully reversible process such variation is partially irreversible for Cobalt Iron Oxides. This relative weakness of Co-iron oxides could become a limiting factor in high density recording systems (such as the IBM 3480 and/or high density microdiskettes). This paper presents experimental evidence on a new Cobalt adsorption system which yealds products whose coercivity losses are fully and completely reversible in the whole range of temperature up to 100°C. In the process of comparing the properties of CrO2vs. Cobalt-Iron Oxides this paper also shows the equivalence of the applicative properties of the two products in terms of output vs. writing current and magnetostrictive effects.     

锂离子电池正极材料LiNiO2的制备和性能研究

本文介绍了以氢氧化锂和氢氧化镍为原料通过高温法合成镍酸锂的方法,并讨论了合成条件对产物电化学性能的影响．实验结果表明,合成反应温度、反应时间、Li／Ni摩尔比对镍酸锂电化学性能有较大的影响,合成出具有电化学活性的镍酸锂需要严格控制反应条件．本文合成出具有高结晶层状结构的镍酸锂,其放电容量可达140mA.h／g;电化学性能比较理想。     

Remote, local, and chemical programming of healable multishape memory polymer nanocomposites

We show that the combination of remote, local, and chemical programming of the multishape memory effects offers unparalleled shape and function control in carbon nanotube-Nafion composites. This strategy not only allows the high-fidelity encoding and extraction of designed material shapes at different length scales (macro, micro, and nano) but also enables the reversible tunability of material functions, such as shape memorizability, mechanical properties, surface hydrophobicity, and material resealability, in a single nanocomposite.     

All-optical switching properties of poly(methyl methyacrylate) azobenzene composites

In this paper, the all-optical switching polymer composites based on poly(methyl methacrylate) (PMMA) and azobenzene dyes were prepared. The optical switching effects of the composites were measured by using 514 nm pump beam and 632.8 nm probe beam. The composites' photoinduced reversible and repeatable change in the transmittance of the probe beam is attributed to the photoisomerization of the azobenzene dyes. The influencing factors of the optical switching properties, such as the modulation frequency, pump beam intensity and temperature, were studied experimentally. The effects of pump beam power and temperature on the optical switching response were also studied experimentally.     

Hierarchical 3D Patterns with Dynamic Wrinkles Produced by a Photocontrolled Diels–Alder Reaction on the Surface

Three-dimensional (3D) reconfigurable patterns with dynamic morphologies enable the on-demand control of surface properties, such as optical, wetting, and adhesive properties, to achieve smart surfaces. Here, a simple yet general strategy is developed for fabricating 3D patterns with reversible wrinkles on the surface, in which a Diels–Alder (D-A) reaction in the top layer, which consists of a reversible cross-linked polymer network composed of a furan-containing copolymer (PSFB) and bismaleimide (BMI), can be spatially controlled by the photodimerization of BMI. When a photomask is used during irradiation with ultraviolet (UV) light, selective photodimerization of the maleimide leads to the diffusion of maleimide from the unexposed region to the exposed region, resulting in the generation of a diffused relief pattern. By controlling the reversible D-A reaction at different temperatures, orthogonal wrinkles can be sequentially and reversibly generated or erased in both the exposed and unexposed regions on the surface. Theoretical modeling with boundary effects reveals that the orientation of the wrinkle in the exposed region is perpendicular to the boundary, whereas the wrinkle in the unexposed region is parallel to the boundary. This strategy, based on a photocontrolled D-A reaction, provides an important and robust alternative for fabricating 3D patterned surfaces with dynamic topographies.     

锂离子电池正极材料LiNiO2的制备和性能研究

本文介绍了以氢氧化锂和氢氧化镍为原料通过高温法合成镍酸锂的方法,并讨论了合成了条件对产物电化学性能的影响。实验结果表明,合成反应温度,反应时间,Ｌｉ／Ｎｉ摩尔比对镍酸锂电化学性能有较大的影响,合成出具有电化学活性的镍酸锂需要严格控制反应条件。     

Electroplastic effect in nanocrystal and amorphous alloys

The influence of the structural and phase state in nanocrystalline and amorphous alloys, as well as the pulsed current modes, on the electroplastic effect is studied under their tension. The decreasing grain size to nanoscale, the emergence of secondary phases, and amorphization in alloys cause the attenuation or disappearance of the electroplastic effect. The application of current pulses upon tension of alloys with a reversible thermoelastic martensitic transformation suppresses the step down of stress on the tensile diagrams caused by the electroplastic effects, but activates the jump up of stress attributed to the shape memory effect.     

The half saturation removal approach and mechanism of Lead (II) removal using eco-friendly industrial fish bone meal waste biosorbent

Lead (II)-laden wastewater from lead acid battery and printed wire board industries are hazardous to human health and environment due to their toxicity and persistent characteristics. This study focuses on eco-friendly industrial Lutjanus erythropterus fish bone meal waste as biosorbent for Lead (II) removal. In this study, the effects of optimization of biosorption, isotherm, kinetic, thermodynamic, characterization of biosorbent were investigated, and the characteristics of biosorbent were compared with those of commercial resins. The half saturation removal of biosorbent amount was determined at 0.09 g in order to represent the excessive metal in real industrial wastewater condition compared to biosorbent and to minimize the consumption of chemicals and biosorption operation time. Such approach is supported by optimization results and Langmuir isotherm. Results obtained were better with Freundlich than with Langmuir isotherm, confirming the presence of heterogeneous monolayer with reversible binding sites. The biosorption mean energy inferred that chemisorption occurred in Lead (II) biosorption, and pseudo-second-order kinetics implied that chemisorption mechanism is the rate-limiting factor. Thermodynamic described an endothermic non-spontaneous reaction with reversible bonding between Lead (II) ions and binding sites. Characterization analysis further confirmed a macroporous surface morphology with multi-binding sites of hydroxyl, carboxyl, and amide groups which contributed to reversible bonding in chemisorption mechanism. The 85 % of recovery supported reversible binding in chemisorption. The biosorbent is at least 70 times cheaper than resins. Hence, this developed biosorbent is a potential candidate to replace resins and can be used in the pretreatment of industrial wastewater application due to cost effectiveness and low environmental impacts. This study successfully gains an insight into green technology by converting waste to a useable product and zero waste concept by minimizing environmental solid management and pollution control.     

One-step fabrication of two-dimensional hierarchical Mn2O3@graphene composite as high-performance anode materials for lithium ion batteries

Two-dimensional (2D) hierarchical Mn2O3@graphene composite is synthesized by a one-step solid-phase reaction.The nanosheets of Mn2O3 are vertically grown on few-layered graphene,constructing a unique 2D hierarchical structure.As an anode material for lithium-ion batteries (LIBs),this hierarchical composite displays excellent electrochemical performances,showing an extraordinary reversible discharge capacity of 2125.9 mA h g-1.Moreover,a record high reversible capacity of 1746.8 mA h g-1 is maintained after 100 cycles at a current density of 100 mA g-1,which retains 82.2 ％ of the initial capacity.Such an outstanding performance could be attributed to its novel structure and the synergistic effects between the Mn2O3 and graphene.     

Thermodynamic correlation tests between magnetostrictive andmagnetomechanical effects in 2% Mn pipeline steel

The thermodynamic correlation between magnetostrictive and magnetomechanical effects is tested using reversible measurements of the uniaxial isostress magnetostrictive and isofield magnetomechanical coefficients. All measurements are on samples of the same 2% Mn pipeline steel, using both tensile and compressive stresses. The agreement is claimed to be satisfactory considering the high sensitivity required for the measurements     

一类二重饱和可逆生化反应扩散模型的 Hopf 分支和 Turing 不稳定性

在齐次 Neumann 边界条件下研究一类具有二重饱和度的四分子可逆生化反应模型，以可逆反应率为参数，利用规范型理论和中心流形定理分别给出常微分系统和扩散系统 Hopf 分支的存在性、方向及其稳定性，并细致研究了扩散系数对系统稳定性的影响。结果表明，当可逆反应率较小时，正平衡点不稳定；当可逆反应率较大时，正平衡点稳定；当可逆反应率介于某一范围内时，扩散系数会对系统的稳定性产生较大影响。此时，当催化剂的扩散系数较小时，系统会产生 Turing 不稳定性。最后，选取满足定理条件的参数，通过数值模拟验证了所得结论。