Transient bimodality in interacting particle systems

We consider a system of spins which have values ±1 and evolve according to a jump Markov process whose generator is the sum of two generators, one describing a spin-flipGlauber process, the other aKawasaki (stirring) evolution. It was proven elsewhere that if the Kawasaki dynamics is speeded up by a factor ^–2, then, in the limit 0 (continuum limit), propagation of chaos holds and the local magnetization solves a reaction-diffusion equation. We choose the parameters of the Glauber interaction so that the potential of the reaction term in the reaction-diffusion equation is a double-well potential with quartic maximum at the origin. We assume further that for each the system is in a finite interval ofZ with ^–1 sites and periodic boundary conditions. We specify the initial measure as the product measure with 0 spin average, thus obtaining, in the continuum limit, a constant magnetic profile equal to 0, which is a stationary unstable solution to the reaction-diffusion equation. We prove that at times of the order ^–1/2 propagation of chaos does not hold any more and, in the limit as 0, the state becomes a nontrivial superposition of Bernoulli measures with parameters corresponding to the minima of the reaction potential. The coefficients of such a superposition depend on time (on the scale ^–1/2) and at large times (on this scale) the coefficient of the term corresponding to the initial magnetization vanishes (transient bimodality). This differs from what was observed by De Masi, Presutti, and Vares, who considered a reaction potential with quadratic maximum and no bimodal effect was seen, as predicted by Broggi, Lugiato, and Colombo.     

喷雾干燥-高温固相法制备纳米LiFePO4与LiFePO4/C材料及性能研究

采用喷雾干燥-高温固相法制备纳米LiFePO₄与LiFePO₄/C正极材料，用X-射线衍射，扫描电镜等对合成材料进行了表征，并对以LiFePO₄为正极的电池进行了电化学性能测试。结果表明:材料合成最佳煅烧温度为600 ℃;合成过程中由于碳对LiFePO₄晶型的生长有一定的抑制作用，相对于纯LiFePO₄材料，LiFePO₄/C材料粒径更小;并且，在此最佳合成温度下合成的LiF     

聚丙烯基纳米碳纤维复合材料结晶行为研究

采用示差扫描量热法(DSC)研究了纳米碳纤维对PP／CNF复合材料中PP结晶行为的影响。结果表明：纳米碳纤雏可提高PP的结晶温度，但略降低其结晶速率和结晶度。提高纳米碳纤雏含量或减小纳米碳纤雏直径，PP结晶行为的上述变化更为明显，但结晶速率随纳米碳纤维含量出现先减小后增大的趋势。     

金属铝燃料电池的研究

铝是一种丰富廉价的有色金属，金属铝电池作为一种新型燃料电池，具有低成本、无毒害、高功率、高能量密度等优点。本文简述了金属铝电池的工作原理，并对铝阳极、空气阴极、催化剂、电解液和铝燃料电池的应用等方面的研究概况进行了叙述。     

聚丙烯/POE共混组成对材料断裂行为的影响

采用基本断裂功(EWF)方法对聚丙烯(PP)/聚烯烃弹性体(POE)共混物的注射双边缺口拉伸试样的断裂行为进行了研究,比较了不同POE含量对共混物各断裂参数的影响.结果表明,PP和用量为5phr POE的共混物都可完全满足EWF方法的要求,共混物的断裂韧性-比基本断裂功we,较PP有显著提高;POE用量为10phr以上的共混物则出现明显的成颈现象而限制了EWF方法的应用;PP和各种POE用量的共混物都得到了其屈服所需要的比基本断裂功we,y和比塑性功β′wp,y.     

熔融浸渍法制备锂离子电池正极材料LiMn2O4的研究

采用LiNO3和MnO2为原料,在650℃下制备了尖晶石型的LiMn2O4.通过X射线衍射、扫描电子显微镜、热重分析和电化学性能测试,发现该化合物具有很高的放电比容量和较好的循环性能,首次放电比容量可达到122 mA·h/g.并对循环性能衰减的各种因素进行了讨论.     

Effect of BaBiO3 and Ba0.6K0.4BiO3 additives on the rechargeability of manganese oxide cathodes in alkaline cells

The effect of the incorporation of small amounts (1–5 wt%) of semiconducting BaBiO₃ and metallic Ba_0.6K_0.4BiO₃ additives on the rechargeability of electrolytic manganese dioxide (EMD) cathodes in alkaline cells in the one-electron regime has been investigated. Both the BaBiO₃ and Ba_0.6K_0.4BiO₃ additives lead to better cyclability compared to the previously known binary oxide additive Bi₂O₃. X-ray diffraction patterns recorded before and after 30 cycles as well as cyclic voltammograms recorded after first and 30 cycles reveal that the better cyclability in the presence of BaBiO₃ and Ba_0.6K_0.4BiO₃ additives is due to the suppression of the formation of unwanted, electrochemically inactive birnessite and hausmannite phases and a shifting of the second-electron capacity of Mn to higher potentials.     

四种硝基苯的电化学行为及其反应活性的理论计算

在滴汞电极上研究了硝基苯、对硝基甲苯、间二硝基苯及2，4-二硝基氯苯的电化学行为，并用量子理论对四种硝基苯化合物的反应活性进行了预测，理论与试验结果基本一致，据此提出了预测分子的电化学活性的方法。     

阴极支撑型固体氧化物燃料电池的制备与测试

采用固相反应法合成A缺位的(La_0.8Sr_0.2)_0.95MnO₃(LSM95)作为阴极材料,Zr_0.9Sc_0.1SO_1.95(SSZ)商业粉体作为电解质材料,溶胶-凝胶法合成的La_0.8Sr_0.2Cr_0.5Mn_0.5O₃-(LSCrM)作为阳极电催化材料,利用流延、共烧结及浸渍法得到结构为LSCrM-CeO₂|SSZ|3YSZ-LSM95的阴极支撑型固体氧化物燃料电池,分别在氢气气氛和甲烷气氛中进行电化学性能测试. 结果表明,浸渍0.11 g·cm ^-2 CeO₂的LSCrM-CeO₂|SSZ|3YSZ-LSM95单电池在以CH₄为燃料时,600、650、700、750和800 ^oC下的功率密度分别为1.68、4.70、12.40、28.08和54.78 mW·cm ^-2,表现出一定的电化学性能和较好的稳定性.     

Thermal behavior of double salt schoenite

The thermal behavior of synthetic schoenite (K₂SO₄·MgSO₄·6H₂)) during heating has been studied by thermal methods. The temperatures of dehydration and decomposition of schoenite have also been determined by DTA, TG and DSC. The thermal reaction equations and the X-ray power diffraction results of the products have been given and the corresponding kinetic parameters have also been obtained.