玻色-爱因斯坦凝聚临界温度的估算

引进有效数密度的概念，对球谐势阱中理想玻色气体的临界温度作了简便的估算，并以此为例讨论应如何将玻色-爱因斯坦凝聚（bEC）的研究引入教学，同时还阐述了这种引入的重要意义.福建省自然科学基

Ideal Quantum Gas in A Process of Throttling Expansion

应用费米积分和玻色积分的特性以及热力学理论,讨论理想量子气体在节流膨胀过程中的特性,导得理想量子气体焦汤系数的解析表达式,详细讨论了低温下量子气体的定压热容和焦汤系数,阐明了系统的量子本性对焦汤系数的贡献。表明理想费米气体的焦汤系数为负而理想玻色气体的为正,因而理想玻色气体适用于低温制冷系统。Using the characteristics of Fermi integral and Bose integral and theory of thermodynamics, We discuss the characteristics of ideal quantum gas in a process of throttling expansion, and an analytical expression of JouleThomson coefficient (JTC) of ideal quantum gas is derived in this paper. The properties of JTC and the specific heat at constant pressure of ideal quantum gas at low temperature are discussed. The contribution of purely quantum nature of system on JTC is examined. It is shown that quantum nature of Fermions contributes to the negative values of JTC while the quantum nature of bosons contributes to the positive values of JTC . Therefore, the ideal Bose gas is suitable for cryogenic refrigeration system.泉州师院科研课题(2002 I 11);; 泉州市科研项目(Z200241

Electrocatalytic and Lifetime Studies of Commercial Catalystsin a PEMFC

　采用自设计的特制H 形电解槽模拟单个氢 空气质子交换膜燃料电池运作,并以电化学方法、SEM及XRD等技术研究两种商用催化剂,即碳载铂(Pt/C)和纯铂钌(Pt Ru)的电催化活性、表面形貌及其结构和寿命.同时对比了两种催化剂分别放在H 形电解槽和常规电解槽中运行情况的测试结果.实验表明,经过H 形电解槽运行后的催化剂,其循环伏安曲线表征氢吸脱的特征峰分别发生了正偏移(Pt/C电极)和负偏移(Pt Ru电极),且对应的峰电流呈现减小的趋势(特别是Pt/C电极).一氧化碳的毒化造成纯铂钌的电催化活性显著下降,其影响是不可逆的.A particularly designed H-type cell was used to simulate the operating condition of a hydrogen-air proton exchange membrane fuel cell (PEMFC). The electrocatalytic activity, morphology, structure and lifetime of commercially available catalysts, carbon support platinum (Pt/C) and unsupported platinum-ruthenium (Pt-Ru), were preliminary studied by carrying out electrochemical measurements and by SEM, XRD techniques. The catalysts were simultaneously tested in the H-cell under operation, and also separately tested in a conventional electrochemical cell for comparison. It was found that the characteristic peaks of hydrogen adsorption/desorption on cyclic voltammograms shifted considerably to a more positive direction for Pt/C, while a more negative direction for Pt-Ru. The magnitude of the peak current densities on CV curves, especially observed from Pt/C catalyst, tended to reduce after the lifetime tests. The electrocatalytic activity of Pt-Ru was significantly lower due to carbon monoxide poison, and the effect of CO on catalyst was irreversible.作者联系地址：厦门大学化学系固体表面物理化学国家重点实验室,厦门大学化学系固体表面物理化学国家重点实验室,厦门大学化学系固体表面物理化学国家重点实验室,厦门大学材料科学与工程系,厦门大学材料科学与工程系,厦门大学化学系固体表面物理化学国家重点实验室,厦门大学材料科学与工程系,美国气体技术研究院 福建厦门,361005 ,福建厦门,361005 ,福建厦门,361005 ,福建厦门,361005 ,福建厦门,361005 ,福建厦门,361005 ,福建厦门,361005 ,伊利诺伊斯60018Author's Address: *1, MA Yan-yun~1, QI Li~1, PENG Cheng~2, CHEN Ling~2, ZHAO Jun~1, ZHANG Ying~2,FAN Qin-bai~3 ysical Chemistry of Solid Surfaces,Xiamen University, Xiamen 361005,China, 2.Department of Materials Science & Engineering, Xiamen University, Xiamen 361005, China, 3. Gas Technology Institute,Des Plaines, IL 60018, US

A UNIFIED DESCRIPTION ON THERMODYNAMIC PROPERTIES of d-DIMENSIONAL FREE AND IDEAL SYSTEM

对能谱为ε＝ APT 型的自由理想系统进行统一的描述，导出d 维系统基本热力学函数的普遍表式.由它可迅速快捷地求得近独立费米子、玻色子和经典体系的所有热力学性质.A Unified description for a d-dimensional free ideal system with energy spectrum of ε=ap t is made.The general expressions of fundamental thermodynamic functions are derived.From them,all thermodynamic properties of ideal fermion,Boson and classical system may be quickly obtained.福建省自然科学基

Phase transition characteristics of Bose-Einstein condensation

【中文文摘】研究玻色 -爱因斯坦凝聚的相变特征 ,证明了粒子间存在弱排斥相互作用的玻色系统的玻色 -爱因斯坦凝聚是二级相变 . 【英文文摘】The phase transition characteristics of Bose Einstein condensation are studied. It is shown that Bose Einstein condensation is a second order phase transition for a Bose system with weak repulsive interaction

Thermodynamic properties of a weaklyinteracting Fermi gas

【中文文摘】根据赝势法导出无外势时弱相互作用费米气体的化学势、内能和定容热容的解析表达式 .在此基础上 ,采用局域密度近似研究谐振势中弱相互作用费米气体的热力学性质 ,探讨粒子间相互作用对系统性质的影响 【英文文摘】The analytical expressions of chemical potential, total energy and heat capacity at a constant volume for a weakly interacting Fermi gas in the absence of exter nal potential are derived by using “pseudopotential" method. Based on the deriv ed expressions, the thermodynamic properties of a weakly interacting Fermi gas t rapped in a harmonic potential are studied under the local-density approximatio n. The effects of interparticle interactions on the properties of the systems ar e discussed.国家自然科学基金 (批准号 :1 0 2 750 51 );; 厦门大学校级自选课题基金 (批准号 :Y0 70 0 8)资助的课

Correlativity Between Concentration of Calcium Applied and Nutrient Element Contents in Fruits and Leaves of Strawberry

研究田间喷施不同浓度醋酸钙对"丰香"草莓头茬果、二茬果和叶片10种营养元素含量的影响,并探明喷钙浓度与草莓果实及叶片营养元素含量间的相关性。结果表明:喷钙明显增加果实和叶片钙、氮、锌、锰含量,外源钙浓度与叶、果中钙、氮、锌、锰含量间基本上呈较显著至极显著正相关;喷钙降低果实钾含量和头茬果期叶片的硼含量,其喷钙浓度与果实钾含量间呈极显著负相关,与头茬果期叶片硼含量间呈较显著负相关;果实和叶片的其余元素(磷、镁、铜、铁)含量基本上与喷钙浓度相关性不显著。A field trial was undertaken to evaluate the effects of various rates of calcium acetate(Ca(CH_3COO)_2. H_2O)solution on the contents of nutrient elements in fruits and leaves of‘Fengxiang'strawberry,as well as the correlation between concentration of calcium applied and contents of nutrient elements in fruits and leaves of strawberry. The results showed that the contents of Ca,N,Zn and Mn in the leaves and fruits increased significantly when the strawberry was treated with the calcium spray,and that the concentration of the exogenous calcium sprayed had positive significant relationship to the contents of Ca,N,Zn and Mn in the leaves and fruit.The K content in the fruit of the first and second crops and the B content in the leaves of the first crop decreased significantly when the strawberry was treated with the calcium spray.The concentration of the exogenous calcium sprayed had significantly negative correlation to the K content of the fruit,and had extremely significantly negative correlation to the B content of the leaves.The contents of P,Mg,Cu and Fe had no significant correlation to the calcium concentration sprayed.福建省自然科学基金项目(C97065

JOULE-THOMSON COEFFICIENT OF IDEAL BOSE GAS

应用玻色系统的基本方程 ,玻色积分的特性以及热力学理论 ,导得理想玻色气体焦汤系数的解析表达式 ,详细讨论了低温下玻色气体的定压热容和焦汤系数 ,阐明了系统的量子本性对焦汤系数的贡献 .表明理想玻色气体适用于低温制冷系统Using the fundamental equations of Bose systems, the characteristics of Bose integral and theory of thermodynamics, an analytical expression of Joule-Thomson coefficient (JTC) of ideal Bose gas is derived in this paper. The properties of JTC and the specific heat at constant pressure of ideal Bose gas at low temperature are discussed. The contribution of purely quantum nature of system on JTC is examined. It is shown that the ideal Bose gas is suitable for cryogenic refrigeration system.泉州市科技项目 (Z2 0 0 2 41);; 泉州师院科研课题 ( 2 0 0 2 I 11)~

Phase transition characteristics of Bose-Einstein condensation

研究玻色 -爱因斯坦凝聚的相变特征 ,证明了粒子间存在弱排斥相互作用的玻色系统的玻色 -爱因斯坦凝聚是二级相变 .The phase transition characteristics of Bose Einstein condensation are studied. It is shown that Bose Einstein condensation is a second order phase transition for a Bose system with weak repulsive interaction

A New Formula For the SpeciFic Heat Jump in Superconduction Transition

应用内可逆循环方法导出一个新的描述超导相变时比热跃变ΔC的ruTgErS公式，反映了超导相变中的不可逆特征，从而可覆盖ΔC实验记录值的较宽范围，比原来的ruTgErS公式优越A new Rutgers Formula For the speciFic heat jump ΔC is derived by means of the method of endoreversible Carnot cycle, which can mirror the irreversible Features in the superconducting transition.Thus, it can cover a wider range of experimentally reported values of ΔC and is superior to the original Rutgers Formula.福建省自然科学基