稀土修饰Al2O3的表面积热稳定性

以不同稀土素为添加剂，采胜浸渍法和捏和法制备了γ－Ａｌ２Ｏ３样品。通过ＢＥＴ、ＸＲＤ等手段，考察了在１２７３Ｋ湿空气中，经不同时间处理γ－Ａｌ２Ｏ３的相变和烧结情况，比较了各样品水热烧结后比表面积的差异，并分析了产生这种差异的原因。     

Sm2O3—CeO2—CuO三元系固线下相关系及电子型超导体Sm2—xCexCuO4…

用Ｘ射线衍射法测定了Ｓｍ２Ｏ３－ＣｅＯ２－ＣｕＯ三元系固线下相关系，样品是在空气气氛１０００℃烧结的。该体系含有一个三元固溶体Ｓｍ２－ｘＣｅｘＣｕＯ４－ｙ，２个三相共存区和３个两相共存区，测定Ｓｍ２－ｘＣｅｘＣｕＯ４－ｙ固溶体的固溶限、氧含量和超导电性，讨论了晶体结构和氧含量对超导电性的影响。     

Sm_2O_3－CeO_2－CUO三元系固线下相关系及电子型超导体Sm_（2－x

用Ｘ射线衍射法测定了Ｓｍ２Ｏ３－ＣｅＯ２－ＣｕＯ三元系固线下相关系，样品是在空气气氛１０００℃烧结的。该体系含有一个三元固溶体Ｓｍ２－ｘＣｅｘＣｕＯ４－ｙ，２个三相共存区和３个两相共存区，测定了Ｓｍ２－ｘ·ＣｅｘＣｕＯ４－ｙ固溶体的固溶限（ｘ＝０．２０），氧含量和超导电性，讨论了晶体结构和氧含量对超导电性的影响。     

氧化锌脱硫中氧的气氛效应及动力学表征

用热重法研究了含氧气气氛中Ｔ３０５氧化锌硫剂脱除Ｈ２Ｓ的微观动力学。实验表明，２００－２９０℃温度范围，脱硫初期为化学反应控制，中后期转移为晶粒扩散控制。Ｏ２存在会阻碍反 进行。气氛中Ｏ２含量小于０．４％（ｍｏｌ）时，在不同控制区，过程对Ｏ２均为－０．５级；Ｏ２含量超过０．４伴随着深度氧化而使脱硫过程复杂化。脱硫反应动力学行为可用未反应收缩核模型描述。给出了不同控制区的参数估值及动力学表达式。对反     

反应气氛对Li4Ti5O12/C复合材料性能的影响研究

以葡萄糖为碳源,采用固相法制备了Li4Ti5O12/C复合材料。探讨了不同反应气氛（N2/O2）对材料物理性质及电化学性能的影响,并通过XRD、BET、电导率、电性能等测试手段对其进行表征。结果表明：氮气气氛中烧结的样品粒度、比表面积、电导率均比空气中烧结样品大。氮气中烧结样品的倍率性能优于空气中 烧结样品,在以0.1C倍率充放电时,首次放电比容量为166.8mAh/g。两样品1C时,经过50次循环容量保持率差别不大。     

反应气氛对Li4Ti5O12/C复合材料性能的影响

以葡萄糖为碳源,采用固相法制备了Li4Ti5O12/C复合材料. 探讨了不同反应气氛(N2/O2)对材料物理性质及电化学性能的影响,并通过XRD、SEM、BET、电导率、电性能等测试手段对其进行了表征. 结果表明,N2气气氛中烧结的样品粒度、比表面积、电导率均比空气中烧结样品大. N2气中烧结样品的倍率性能优于空气中烧结样品,在以0.1 C倍率充放电时,首次放电比容量为166.8 mA·h/g. 2种样品在1 C时,经过50次循环容量保持率差别不大.     

Ni—La2O3复合镀层的氧化行为及机制

通过对金属镍、镍镀层及Ｎｉ－Ｌａ２Ｏ３复合镀层于９００℃、１０００℃时的恒温氧化实验，发现Ｎｉ－Ｌａ２Ｏ３复合镀层的氧化行为明显改善。高分辨电子显微镜（ＨＲＥＭ）的观测研究表明，Ｎｉ－Ｌａ２Ｏ３复合镀层氧化时，纳米尺寸的Ｌａ２Ｏ３颗粒掺入到氧化层中，形成了ＮｉＯ－Ｌａ２Ｏ３复合氧化物层；在氧化层晶界发现了异常原子排列的新现象。由此认为，Ｎｉ－Ｌａ２Ｏ３复合镀层抗高温氧化性能的提高，主要归因于小尺寸     

SO_4~(2-)/ZrO_2-SiO_2催化剂的酸性及结构表征

采用指示剂法及吸附吡啶的红外光谱法，考察了催化剂的酸性；用ＸＲＤ、ＩＲ、ＸＰＳ及热分析等对催化剂的结构进行了表征；用ＢＥＴ法测定了催化剂的比表面积，并研究了催化剂的组成及焙烧温度对催化剂比表面积的影响．实验结果表明，一般在４５０℃以上焙烧的ＳＯ４２－／ＺｒＯ２ＳｉＯ２催化剂均具有超强酸性，催化剂的酸强度随焙烧温度的增高有所增强；吸附吡啶的红外光谱表明该催化剂具有较高的Ｌｅｗｉｓ酸量．通常８００℃以下焙烧的催化剂均为非晶态，高于８００℃焙烧硅锆比大于９的样品时，可得到一种新的结晶态物质．催化剂的比表面积一般在４００ｍ２／ｇ左右．     

Ni－La_2O_3复合镀层的氧化行为及机制

通过对金属镍、镍镀层及Ｎｌ－Ｌａ２ｏ３复合愤层于９００℃、１０００℃时的恒温氧化实验，发现Ｎｌ－Ｌａ２Ｏ３复合镀层的氧化行为明显改善。高分辨电子显徽镜（ＨＲＥＭ）的观测研究表明，Ｎｉ－Ｌａ２Ｏ３复合铰层氧化时，纳米尺寸的ｋａ２Ｏ３颗粒掺人到氧化层中，形成了ＮｉＯ－Ｌａ２Ｏ３复合氧化物层；在氧化层晶界发现了异常原子排列的新现象。由此认为，Ｎｉ－Ｌａ２Ｏ３复合镀层抗高温氧化性能的提高，主要归因于小尺寸的纳米颗粒可微量溶解，成为Ｌａ（３＋）的晶界们聚“源”，阻止Ｎｉ（２＋）的短路向外扩散，从而改善了氧化层的微观结构和生长机制。     

制备方法对NiP非晶态合金性质及催化活性的影响

分别使用三种方法制备了NiP非晶态合金：次磷酸钠还原镍盐（方法1）、次磷酸镍自分解（方法2）和使用有机胺调节溶液pH值的次磷酸还原镍盐（方法3）。研究了产品的物性，并以环丁烯砜加氢反应为探针检测了NiP非晶态合金的催化活性。研究结果表明，次磷酸钠体系制备的产品性质比较稳定，条件的改变对产物性质的影响不显著，催化活性一般在50%～60%之间；次磷酸镍体系中制备的样品显示出较高的催化活性，环丁烯砜转化率在90%以上；次磷酸体系制备样品的性质对条件变化较为敏感，催化剂的活性在70%～98%之间波动。发现方法2得到的NiP非晶态合金呈现为分散的完美的球形颗粒，且颗粒之间不存在聚集现象；使用方法3可以得到高比表面积的NiP非晶态合金。两种新方法所制备的NiP非晶态合金具有较小的粒径、较高的比表面积、较高的热稳定性和较高的催化反应活性。     

Investigation of the sorption of water vapor on cation-substituted vermiculite. 2. Thermodynamic description of sorption equilibria

The changes in the thermodynamic functions of the sorbents were calculated for the first time from measurements of the deformations of vermiculite during the sorption of water vapor and adsorption-calorimetric data.Institute of Physical Chemistry, Russian Academy of Sciences, 117915 Moscow. Institute of Colloid Chemistry and the Chemistry of Water, Academy of Sciences of the Ukraine, 252180 Kiev. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1270–1275, June, 1992.     

土地改革之“三权分置”入法及其实现障碍的解除—评《农村土地承包法修正案》

农地“三权分置”政策入法关涉《农村土地承包法》修正和民法典物权编之编纂,已完成大修的《农村土地承包法》有其亮点,但对其与民法典物权编的关系尚未妥当处理,立法者在法律规则设计中亦没能体悟透彻政策意蕴。其制度设计有违在立法中的规范作用,混淆民法物债二分的基本原理,忽视法体系化与协调适用的要求,对乡村重要实际问题的系统解决态度有轻怠之嫌。落实农地“三权分置”政策的应然立法路向及其解释是：与“落实集体所有权”精神有效衔接,重申并进一步确立土地承包经营权的科学地位,精确界定土地经营权的内容和性质,为农地规模经营亟需的金融担保提供法治的正当性的支持。     

Thermodynamics of ionization of water over wide ranges of temperature and pressure

We have summarized results of many experimental investigations of the thermodynamics of ionization of H₂O(liq.) from 0–300°C and from 1.0 atm to nearly 8000 atm. Results of these investigations (equilibrium constants, enthalpies of ionization, heat capacities, partial molal volumes, and compressibilities) have been used for a number of thermodynamic calculations. It is particularly noteworthy that it is possible to use thermal data from 0–145°C with an equilibrium constant for 25°C in calculating reasonably accurate equilibrium constants for temperatures as high as 300°C. Similarly, it is possible to use volumetric data that refer to 1.0 atm in calculating useful equilibrium constants that apply for pressures as high as 2000 atm.Much of the work reported here was done while the author was on leave at the University of Lethbridge.     

Thermodynamics of lonization of aqueous lodic acid,an “almost-strong” electrolyte

We have made calorimetric measurements of enthalpies of dilution of aqueous iodic acid and have used these results for evaluation of the standard enthalpy of ionization of HIO₃(aq.). We have also made calorimetric measurements of enthalpies of addition of perchloric acid solution to aqueous solutions of KIO₃, KNO₃, NaIO₃, and NaNO₃ and have used these results to obtain further values for the standard enthalpy of ionization of HIO₃(aq.). On the basis of all these results, we have selected H^o=–660±125 cal-mole^–1 as the best available standard enthalpy of ionization of HIO₃(aq.) at 298.15°K, compared to the previously accepted –2400 cal-mole^–1. Using the best available K=0.157 for ionization, we also obtain G^o=1097 cal-mole^–1 and S^o=–5.9 cal-^oK^–1-mole^–1 for ionization of HIO₃(aq) at 298.15°K.On study leave from Department of Inorganic and Analytical Chemistry, LaTrobe University, Bundoora, Victoria, 3083, Australia, to University of Lethbridge.On study leave from Department of Chemistry, University of Wollongong, Wollongong, N.S.W. 2500, Australia, to University of Lethbridge.     

Thermochemical study of aliphatic and phenyl-substituted geminal diacetates

The standard enthalpies of combustion _c H ^o of aliphatic diacetates1 and aromatic diacetates2 were measured calorimetrically. The enthalpies of vaporization _vap H ^o or sublimation _sub H ^o of1 and2 were obtained from the temperature function of the vapor pressure measured in a flow system. From _f H ^o(g) of1 and2 new values of group increments for the estimation of standard enthalpies of formation of these classes of compounds were derived. The geminal interaction energy between the geminal acyloxy groups shows no anomeric stabilization.Geminal Substituent Effects, Part 12, for part 11 see Ref. 7.     

Relation between characteristic adsorption energy and internal pressure in the theory of volume filling of micropores

An equation for the internal pressure acting on an adsorbate in micropores was obtained on the basis of the assumption that the chemical potential of an adsorbate in micropores is equal to that in an equilibrium gas phase and using the Dubinin-Radushkevich equation. The empirical relation between the characteristic adsorption energy and the half width of pores was expressed in terms of internal pressure and diameter of adsorbate molecules. The two-dimensional pressure was calculated for micropores with plane-parallel walls, where the width of a micropore coincides with the diameter of an adsorbate molecule. The results obtained were compared with the two-dimensional pressure of a monolayer on a free planar surface for an adsorbate and adsorbent of the same nature.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1928–1930, October, 1995.     

Thermochemistry of aqueous solutions of alkylated nucleic acid bases. VIII. Enthalpies of hydration of 6-alkyluracils

Enthalpies of solution in water H _sol ^o and enthalpies of sublimation H _sub ^o were determined for a number of crystalline derivatives of uracil: 1,6-dimethyluracil (m ₂ ^1,6 Ura), 1,3,6-trimethyluracil (m ₃ ^1,3,6 Ura), 6-ethyl-1,3-dimethyluracil (e⁶m ₂ ^1,3 Ura), 6-propyl-1,3-dimethyluracil (pr⁶m ₂ ^1,3 Ura) and 6-butyl-1,3-dimethyluracil (but⁶m ₂ ^1,3 Ura). Standard enthalpies of hydration H _hydr ^o and standard enthalpies of interaction H _int ^o of the solutes with their hydration shells were calculated. The data obtained show that dependence of H _int ^o on the number of-CH₂- groups of n-alkyl chain added upon substitution of diketopyrimidine ring is nonlinear. This finding is discussed in connection with results of X-ray diffraction structure determinations for the crystalline compounds.     

STUDIES ON THE REACTIVITY PATTERNS OF HETEROCYCLICS IN AQUEOUS DMSO‐INTERACTION BETWEEN POSITIVE END OF SULFOXIDE DIPOLE AND LONE PAIR ON RING NITROGEN IN PYRIDINE DERIVATIVES

Abstract

The signals for the α, β, and γ protons of pyridine exhibit a downfield shift in DMSO-d₆, compared to CCl₄ as solvent, the order being γ > β > α. This is attributed to an interaction between the positive end of the DMSO dipole and the lone pair of electrons on the ring nitrogen. This effect is also reflected in the faster rate of alkaline hydrolysis of ethyl isonicotinate over ethyl nicotinate and ethyl picolinate in aqueous DMSO relative to aqueous ethanol. Similar solvent effects are also observed in the pmr spectrum of pyrazine.     

Protonation of leucoemeraldine in the solid state and in solution

The protonation of leucoemeraldine in power form and in N-methylpyrrolidinone (NMP) solution by HCIO₄ and HBF₄ has been studied by x-ray photoelectron spectroscopy (XPS), infrared (IR), and ultraviolet (UV)-visible absorption spectroscopy. In powder form, less than 25% of the amine nitrogens can be protonated in the absence of oxygen. The effects of oxygen on the degree of protonation and the distribution of amine and imine units upon deprotonation of the salt are investigated. The degree of protonation in leuccemeraldine can be increased to about 50% with 3 M HCIO₄, similar to that achievable with emeraldine base in powder form. In NMP solution, leucoemeraldine is easily oxidized by dissolved oxygen. Protonation of both leucoemeraldine and emeraldine base in NMP solutions results in metastable species which gradually undergo deprotonation. The resulting products are affected by the O₂ content of the solutions. © 1993 John Wiley & Sons, Inc.     

钾明矾溶液水解度计算公式

根据盐类水解关系式和水的离子积计算公式,建立了计算盐类水解度和水解产物离解常数的完全方程式。计算值同实验值比较,钾明矾溶液水解度平均偏差为0.6％,离解常数pK_b=11.6±0.1,水的离子积pK_w平均偏差小于0.06,从而改进了苏联的计算公式。