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。     

碳量子点上转换材料的制备及其应用研究进展

碳量子点(CQD)具有化学惰性,生物相容性和低毒性等优势,可能在能源、生物医药等领域得到广泛的应用. CQD可通过表面被聚合物(例如PEG)钝化而表现出很强的光致发光特性.在生物成像,疾病检测和药物输送中使用表面钝化后的功能化生物分子更为有效.并且碳材料由于其优异的电化学性能还展现出在催化、电子器件等许多领域广泛的应用前景.我们将对近年来碳量子点发光材料的研究进行总结,并讨论碳量子点在能源、环境和其他一些领域的应用.     

数据离群值的检验及处理方法讨论

由目前普遍使用的分析化学教材中与离群值相关的内容出发,对其进行对比和分析,说明数据离群值检验的意义和重要性。对几种常见的离群值判定方法进行了列举和比较,并对已确认为异常值的数据的处理方法也进行了对比和讨论。各种检验和处理方法各有其优势和劣势,根据实际情况选择不同方法或多种方法配合使用,能够更好地实现对离群值的检验和处理。     

乙醇辐解机理研究

本文研究了氧、温度和4-甲基-4-苯基-2-戊酮(Mpp)对乙醇辐解的影响。Mpp在实验使用的浓度范围内对乙醛的G值没有影响, G(2,3-丁二醇)值随Mpp浓度增加而下降, 最后达0.9恒值。使用Mpp求得原初过程形成的G_(H_2)=1.9, 动力学处理求得G_H=2.4, k_(12)/k_(11)=(11.9±1.8)×10~3。实验证明Mpp清除了体系中的H原子, 抑制了CH_3CHOH自由基的形成, 从而抑制了2,3-丁二醇的生成, 但不影响乙醛的产额。这一研究否定了传统文献所述的在γ辐解乙醇时相当量的羟乙基自由基歧化反应生成乙醛。本文还对乙醇γ辐解机理进行了讨论, 并求得了乙醇辐解的物料平衡。     

计量数比规则与等物质的量规则的比较

指出了计量数比规则存在的缺陷:不利于贯彻有关物质的量及其单位摩尔的SI规定,不能继承当量定律的数据资料,不能表示反应的性质,不能正确表达水硬度、碱度、树脂交换容量及电解定律,缺乏科学的导出过程及计量关系表达式,计算过程繁杂。而等物质的量规则继承和发展了当量定律,使整个滴定分析计算简单规范。     

锌在植物中的形态及生理作用机理研究进展

对锌在植物中的形态及锌在植物生理过程中的作用机理进行了综述和讨论,表明锌对碳水化合物代谢,蛋白质代谢,植物生长素代谢及细胞膜的功能和结构有很大影响。此外,锌与植物病害也有很大关系。     

对离子反应发生条件中“放出气体”的再认识

离子反应发生条件中的“放出气体”,与其他资料中对生成物的描述不一致,也与有关反应事实不符。“放出气体”的出现,使教材中对气体生成物的描述时此时彼,没有时序性、规律性。对其与化学反应的关系及其与“生成气体”的区别进行了论述,并提出了修改的建议。     

Many-Body Rayleigh-Schrödinger Perturbation calculations of the correlation energy of open shell molecules in the restricted Roothaan-Hartree-Fock formalism. Application to heats of reaction and energies of activation

The title technique was applied to a series of elementary chemical reactions. Second and third order contributions to the correlation energy were computed for the basis sets of the double zeta and double zeta plus polarization quality. Calculated heats of reaction and energies of activation were compared with the experimental data and the results of the bestab initio calculations reported in the literature.     

Dehydrogenation of Ethanol Over Cu/ZnO Catalysts Prepared from Various Coprecipitated Precursors

For the title reaction, Cu/ZnO catalysts prepared from aurichalcite were more active than those prepared from other precursors. Selectivity to ethyl acetate over Cu/ZnO was much higher than that over Cu/SiO₂ This revised version was published online in June 2006 with corrections to the Cover Date.     

诠释学的历史性与儒家经典起源

利科提出了历史意义的三重诠释,在历史事件的陈述、构成传统的历史解释之外,还有一种理解的历史性或诠释学的历史性。这种历史性是对历史叙事本身的反思,构成一种哲学的追问与精神性的溯源,而不是仅仅停留在对于事实性的考辨上。从这样的历史性理解出发,我们可以暂且超离实物、图像和文字,以及各种历史材料本身所带来的有限性之束缚,而由对象物演变的逻辑来还原或者想象历史演变所可能存在的路径,以勾勒出从“无言”世界进入到“有言”世界的图景。儒家的经典以六经为根本,而六经的起源与儒家所建构的文明史、历史观是交叠在一起的,仅从历史的事实性考论入手,我们无法说清楚这些材料的真实来源,尤其不能解释这些文献何以变成了具有某种神圣性特征的典籍。所以,儒家经典的起源就不只是文献自身的历史,它也包含了观念的演化史和精神的扩展史,是一个不断的诠释和一系列思想填充活动的结果。从口传记忆到书写记忆,从片段无序的材料到结构谨严的文本,从一般性的历史文献到体系化的哲学经典,这个漫长而又复杂的历程,既是六经成型的前史,也是六经的演化史与建构史,正是在原本混沌迷离的状态中,六经系统才慢慢地成长起来,儒家经典的基本面貌也变得越来越清晰化,最终以华夏文明之根本正典的身份呈现于世。     

含羧基/环氧树脂的丙烯酸酯共聚物乳液的制备和交联——1.含羧基丙烯酸酯共聚物乳液的分子设计和制备

以在低温下(<100℃)实现含羧基/环氧树脂的丙烯酸酯共聚物乳液的交联固化为目的,进行了分子设计;估算了共聚物的组成,用碱滴定法测定了乳胶粒表面的羧基数,并比较了不同单体配比所得乳液的成膜性能.