NaCl在CH~3OH-H~2O混合溶剂中活度系数的测定(298.15K)

用电动势法测定了298.15K时,由Na^+和Cl^-离子选择电极组成的电池在NaCl-CH~3OH-H~2O混合体系中的电动势,用扩展的Debye-huckel方程和Pitzer方程关联不同溶剂组成下电动势的实验值,得到电池的标准电动势能和NaCl 在混合溶剂中的活度系数.将Pitzer-Simonson方程应用于含离子缔合体系.求出NaCl 在混合溶剂中的缔合常数,结果表明NaCl在甲醇含量为60%时,可能已有离子对生成     

电化学中E和Δ_rG_m的非唯一对应性

指出了电化学反应中n值的非唯一确定性 ,阐述了电化学反应的Gibbs自由能改变值ΔrGm 与其可逆电池电动势E之间的非唯一对应关系。     

在不同温度下Cu|CuSO_4|Hg_2SO_4-Hg电池标准电动势的确定

许多作者利用铜电极和汞-硫酸亚汞电极组成电池,研究硫酸铜的热力学性质,但该电池的标准电动势都是用扩展的Debye-Hükel公式外推得到的,由于Debye-Hükel公式中的离子大小参数无法实验直接测定,在选用时会给结果带来某些不确定性。本文测定了5～45℃间隔为10℃的电池。Cu|CuSO_4|Hg_2SO_4~-Hg (A)的电动势,在Pitzer电解质溶液理论基础上,提出了新的确定电池电动势的方法。     

第5届全国大学生化学实验邀请赛(试卷C2)实验C2 电动势法测定化学反应的热力学函数

一、基本原理1化学电池电动势和温度系数的测定本实验采用补偿法(也称对消法)测量电池的平衡电动势,在待测电池上并联一个反向的外加电势,调节回路使得通过待测电池的电流趋近于零,测量待测电池的电动势。改变实验温度,测量不同温度下电池的电动势,求出电池电动势与温度的关系,     

电化学中E和ΔrGm的非唯一对应性

指出了电化学反应中n值的非唯一确定性，阐述了电化学反应的Gibbs自由能改变值△rGm与其可逆电池电动势E之间的非唯一对应关系。     

浓差电池中几个问题的讨论

概括浓差电池正负极的判断方法和有液接电势存在时浓差电池电动势的求法,分析了液接电势的存在对浓差电池电动势大小的影响。     

可逆电池电动势計算方法的商榷

計算可逆电池的电动势常有三种方法,卽E==E_左—Z_右,E=_右—E_左和E=E_1十E_2。上述三式都用Ef表示电极电位,并假定液体接界电位和金属接触电位巳被消除忽略不計,电池电动势就等于两极电位差或代数和。根据这三种方法算出同一可逆电池齣电动势数值都是相等的,但同一个电极电位常有正負号相反絕对值相同。所以产生三种算法,只由于人     

混合溶剂中氨基酸热力学性质的研究 Ⅳ.278.15—318.15K下甘氨酸-乙醇-水体系

在混合溶剂中恒定乙醇的质量百分数x=10％,应用电动势法测定了无液接电池(A)和电池(B)的电动势。根据电池(A)和电池(B)的电动势,用传统的Debye-Huckel外推法和我们在前文提出的多项式逼近程序,确定了甘氨酸在278.15—318.15 K范围内5个温度下的第一、第二热力学解离常数,两种方法所得的结果在实验误差范围内一致。并相应计算了该体系的热力学量。     

混合溶剂中氨基酸热力学性质的研究 IV: 278.15-318.15K下甘氨酸-乙醇-水体系

在混合溶剂中恒定乙醇的质量百分数χ=10%, 应用电动势法测定了无液接电池(A)和电池(B)的电动势。根据电池(A)和电池(B)的电动势, 用传统的Debye-Huckel外推法和我们在前文提出的多项式逼近程序, 确定了甘氨酸有278.15-318.15k范围内5个温度下的第一、第二热力学解离常数, 两种方法所得的结果在实验误差范围内一致。并相应计算了该体系的热力学量。     

混合溶剂中氨基酸热力学性质的研究 IV: 278.15-318.15K下甘氨酸-乙醇-水体系

在混合溶剂中恒定乙醇的质量百分数χ=10%, 应用电动势法测定了无液接电池(A)和电池(B)的电动势。根据电池(A)和电池(B)的电动势, 用传统的Debye-Huckel外推法和我们在前文提出的多项式逼近程序, 确定了甘氨酸有278.15-318.15k范围内5个温度下的第一、第二热力学解离常数, 两种方法所得的结果在实验误差范围内一致。并相应计算了该体系的热力学量。     

Proton mobility in hydrated sulfonated polystyrene: NMR and impedance studies

Different ionomers were obtained by sulfonation of a commercial polystyrene (PS), using acetyl sulfate as reagent. The sulfonation was assessed by FTIR and XPS spectroscopies and the thermal and mechanical properties were deduced from DMA measurements. The acid form of the ionomers was characterized by means of ¹H and ¹³C MAS-NMR spectroscopies. Polymer hydration under controlled humidity atmosphere was analyzed by gravimetric, NMR and complex impedance techniques. In the hydrated state, two stages associated with formation of hydronium (H₃O⁺) species and proton hopping between adsorbed water molecules were deduced from NMR data. Both processes are responsible for important changes detected in mechanical properties and conductivity of sulfonated polymers during hydration processes.     

HETEROGENEOUS PHOTO CATALYSIS–VII. THE INFLUENCE OF ZINC IONS ON THE PHOTOCATALYTIC PROPERTIES OF PLATINIZED CADMIUM SULFIDE

Abstract— The reaction rate of the CdS/Pt-catalyzed hydrogen evolution and photodehydro-dimerization from aqueous 2,5-dihydrofuran depends strongly on the reaction conditions in the preparation of CdS/Pt by photoplatinization. Highest rates, 12 ml H₂/h, are obtained when the photocatalyst was prepared with a low-intensity lamp in the presence of 4.3 mol% of platinate (sample I) while lower rates are observed with 1.07, 2.15, 3.23 and 6.45 mol% Pt. At higher intensity and 4.3 or 2.15 mol% Pt the produced samples II and III induce rates of 5 or 2.5 ml H₂/h. Addition of zinc sulfate to the 2,5-dihydrofuran solution results in a maximum rate increase to 7.5 and 12.5 ml H₂/h in the case of II and III , respectively. Similarly, zinc sulfate improves the catalytic properties also when it is present during photoplatinization. In this case only half the amount of platinum, 2.15 mol%, is necessary to obtain the highest rates of 12 ml H₂/h.     

THE DEPENDENCE OF PHOTOSENSITIZING EFFICACY OF ACRIDINE ORANGE AND TOLUIDINE BLUE ON THE DEGREE OF SENSITIZER-CELL INTERACTION

Abstract— Previous work of photosensitizing action in vivo has commonly been performed under the 'steady' conditions where the sensitizing dye is equilibrated with the cells by allowing ample time for the sensitizer-cell interaction prior to light illumination. The present experiments, by combining a fast mixing technique (20 ms) with short illumination (mostly & < 10 s), intended to measure the change in the efficacy of the sensitizing action on yeast cells during a short period of time starting from the mixing of the two components, sensitizers and cells. We found that the efficacy of the sensitizing action of acridine orange (AO) began to increase within 20 s and continued to do so until at least 10 min. This was true both for the inactivation and the induction of genetic changes. Similar experiments with toluidine blue (TB), which is believed to be normally unpenetrable into the cell, showed no such fast change characterized by a time of less than 60 s, but unexpectedly revealed a small but significant increase in the efficacy after 20–30 min of mixing. This slow change may indicate that TB can penetrate slowly into the hydrophobic region in the membrane, and as a result, it exerts action with a higher efficiency than it remains in the outside medium. The increased induction of genetic changes beyond control level with the fast (& < 60s)TB sensitization in H₂O and D₂O medium is discussed in terms of the diffusiveness of ¹O₂ into the cell interior.     

芘四硫酸四钠盐/甲基紫精复合物光物理性质的研究

本文通过吸收光谱滴定和时间分辨瞬态吸收光谱对芘四硫酸四钠盐(pyrenetetrasulfonic acid tetrasodium salt,PyTS)/甲基紫精(methylviologen,MV²⁺)复合物在水溶液中的光物理性质进行研究。用甲基紫精滴定芘四硫酸四钠盐时,得到该复合物的组成成份是1:1,反之,用芘四硫酸四钠盐滴定甲基紫精时,同样得到1:1组成成份的复合物。该复合物的形成常数是2.4×10⁶mol^-1·L,当用光激发该复合物时,发现其中存在芘四硫酸四钠盐到甲基紫精的电子转移过程,并得到该过程的动力学模型。     

杂多酸催化剂上乙苯的氧化脱氢

本文研究了H₃PW₁₂O₄₀及其Na⁺、Al³⁺、Cd²⁺、La³⁺盐对乙苯氧化脱氢反应的催化活性。发现活性与酸强度和酸量之间没有直接的关系。杂多酸及其盐类在反应开始阶段均存在一段活性增长期,简称为"增活期"。增活期内催化剂表面的积炭量逐渐增加,积炭物的H/C比逐渐减小。用质谱法、薄板层析法检知了积炭物中有醌类物质存在,提出了积炭物中的醌类基团是氧化肥氢的活性中心的观点。     

WAVELENGTH EFFECTS ON THE PHOTOPROCESSES OF INDOLE AND DERIVATIVES IN SOLUTION

Abstract— The two main primary photoprocesses (electron ejection and H-atom release) for indole, 5-methoxyindole and N-methylindole in various polar and nonpolar solvents were studied as a function of the excitation energy and were correlated with the corresponding fluorescence quantum yields. In hydrocarbon solvents, N–H bond cleavage is the main primary photoprocess from the ¹B_b band of the substrates with the exception of N-methylindole. In alcohols, both processes are of negligible importance. Hydrated electrons (e⁻_aq) are ejected from the relaxed singlet states of all three compounds in aqueous solutions with a similar yield for excitation at 280 and 254 nm (¹L_a and ¹L_b states). The yield increases when the excitation is into the ¹B_b band. The quantum yields of the two primary processes from the higher excited states are generally lower than the fraction of molecules not converting to the fluorescent state. This is explained by an efficient back reaction in competition with a thermally activated radical release from an intermediate state or radical pair formed from the S₂ (¹B_b) state. The non-occurrence of a photoionization energy threshold is discussed.     

SPECTRAL AND TIME DEPENDENCE STUDIES OF THE ULTRA WEAK BIOLUMINESCENCE EMITTED BY THE BACTERIUM Escherichia coli

Abstract— Weak luminescence was detected using photon counting equipment, from oxygenated, liquid cultures of Escherichia coli during two stages of its growth cycle. The first period of emission occurred during the exponential phase of growth and comprised a UV(210–330 nm) band and a visible region(450–620 nm) band, the total intensity being (1.65 ± 0.12) x 10³ counts s^-1. The second period of emission occurred during the stationary phase of growth and comprised only a visible region(450–620 nm) band of intensity (8.72 ± 0.15) x 10³ counts s^-1. When the growth temperature was raised from 306.15 to 310.15 K, the above emission intensities were approximately halved, but the spectra were not changed significantly. No luminescence was observed at either temperature when the E. coli was grown anaerobically. The visible region luminescence was attributed to excited carbonyl groups and excited singlet O₂ dimers formed during the decomposition of lipid peroxides. The UV component was tentatively assigned to oxidative side reactions accompanying the synthesis of proteins.     

ULTRASTRUCTURAL STUDIES ON THE MECHANISM OF THE PHOTODYNAMIC THERAPY OF TUMORS

Abstract Balb/c mice bearing a transplanted MS-2 fibrosarcoma were injected with 2.5 mg kg ¹ of either tetra(4-sulfonatophenyl/porphine (TPPS) in phosphate-buffered saline or 0.5 mg kg⁻¹ of Zn²⁺-phthalocyanine (Zn-Pc) incorporated into unilamellar liposomes of dipalmitoyl-phosphatidylcholine. Chromatographic studies showed that TPPS is mainly transported in the serum by globulins and albumin, while Zn-Pc is specifically bound by lipoproteins. Exposure of the injected mice to red light (300 J cm⁻²) caused extensive tumor necrosis. The ultrastructural analysis of tumor specimens taken from mice at 15 h after PDT showed that TPPS photoinduces a preferential necrosis of the neoplastic cells, while Zn-Pc causes severe photodamage to both the vascular system and the neoplastic cells. The different modes of tumor photosensitization by TPPS and Zn-Pc are discussed on the basis of the transport mechanism of the two dyes.     

THE EFFECT OF PHOTODYNAMIC TREATMENT OF YEAST WITH THE SENSITIZER CHLOROALUMINUM PHTHALOCYANINE ON VARIOUS CELLULAR PARAMETERS

Photodynamic treatment of Kluyveromyces marxianus with chloroaluminum-phthalocyanine resulted in loss of clonogenicity. Several parameters were studied to identify targets that could be related to loss of colony-forming capacity. Inhibition of various plasma membrane-bound processes was observed, such as substrate transport and plasma membrane ATPase activity. Moreover, K+ loss from the cells was observed. Photodynamic treatment also reduced the activity of various enzymes involved in energy metabolism, thereby decreasing the cellular ATP level. It will be discussed however that none of these processes is likely to be related directly to loss of clonogenicity. Treatment with phthalocyanine and light resulted in a strong inhibition of the incorporation of 14C-phenylalanine in trichloracetic acid-precipitable material. The induction of the β-galactoside utilization system was also strongly inhibited. The latter two processes did not recover during incubation, subsequent to photodynamic treatment. It is concluded that photodynamically induced inhibition of protein synthesis is a critical factor contributing to the loss of clonogenicity.     

苯酚型成青成色剂的活性和结构的关系

本文研究了11个苯酚型成青成色剂的活性和其结构的关系。以T.S.S.(N,N-二乙基对苯二胺硫酸盐)为显影剂,采用外偶法对这些成色剂进行彩色显影,结果证明,其彩色显影动力学符合Elvegard关系式。本研究中,用HMO方法计算了这些成色剂的偶合位置的超离域度S_r^(E)。作为化学活性的表征,研究中发现,此参数能较好地反应成色剂的偶合活性,并发现,成色剂偶合位置的邻位取代基对彩色显影的偶合反应有空间障碍作用。