Application of Iodide Ion Selective Electrode to the Study of Stepwise Formation Constant and Solubility Product of Lead Iodide

Iodide ion-selective electrode were studied, prepared and applied for the complex formations and solubility product determination. The thermodynamic formation constant of PbI⁺ and the solubility product of PbI₃ were found to be 54 and 9.2 × 10^?9, respectively. The formation constant of PbNO₃⁺ was calculated to be 4.6 from the different formation constant of PbI⁺ in perchlorate and nitrate media.     

Relationship between mutagenesis and carcinogenesis.

Abstract— Since the neoplastic condition is a phenotypic expression of the genome of the tumor cells, it is reasonable to assume that the neoplastic state can be the result of the alteration of gene activity by either mutagenesis or gene modulation. The review of the literature seems to support the hypothesis that both mutations and epigenetic processes are components to carcinogenesis. Consistent with the mutation theory of cancer are: (1) the clonal nature of tumors; (2) the mutagenicity of most (but not all) carcinogens; (3) correlation of high mutation frequencies in cells of cancer-prone human fibro- blasts lacking DNA repair enzymes; (4) correlation of in vitro DNA damage, in vitro mutation and transformation frequencies with in vivo tumorigenesis; (5) age-related incidences of various hereditary tumors; and (6) the correlation between photoreactivation of DNA damage and the biological amelioration of UV-induced neoplasms. Supporting the epigenetic theory of carcinogenesis is the reversion of certain types of neoplastic cells to a state allowing normal development. These latter studies demonstrate the totipotency of the genes in some types of malignant cells. An integrative theory of carcinogenesis is presented that synthesizes the mutation and epigenetic theories with Comings' general theory of carcinogenesis and the 2-stage theory of carcinogenesis. Data are presented that test the predictions of the 2-stage theory of carcinogenesis, and that support the hypothesis that mutagenesis plays a major role in carcinogenesis (initiation phase) and that gene modulation of repressed mutations is responsible for tumor promotion.     

Concentration and determination of trace organic pollutants in water

Organic pollutants in water are isolated on a mini-sampler tube containing a macroporous resin. The sorbed pollutants are next thermally transferred to a second sorption tube and then to an analytical column where they are separated and determined by temperature-programmed gas chromatography. Excellent recoveries were obtained for tests in which model organic compounds of various classes were added to water. The water sample is much smaller than that required with previous analytical methods.     

Studies on the thermotropic liquid crystalline polymer. VII. Synthesis and properties of photocrosslinkable poly(ether-ester) containing cinnamic group

A series of semi-aromatic poly(ether-ester)s containing cinnamic group was prepared from 4,4′-diacrylic acid-α,ω-phenoxyalkanes with diols in the presence of diphenylchlorophosphate (DPCP) and pyridine as a catalyst and solvent. The phase behavior of these polymers was studied by differential scanning calorimetry (DSC), optical polarizing microscopy equipped with a heating stage, and wide-angle x-ray diffraction (WAXD). All of the poly(ether-ester)s, except P3 , show nematic or smectic thermotropic liquid crystalline behaviour under optical polarizing microscopic observation. These polymers can undergo photocrosslinking reaction upon heating, as examined by IR, solubility, and DSC analysis. © 1993 John Wiley & Sons, Inc.     

Electrospun nanofibers of poly（vinyl pyrrolidone）/Eu^3＋ and its photoluminescence properties

Nanofibers of poly（vinyl pyrrolidone） （PVP）/Eu^3＋ with diameters of 300-900 nm were prepared by using sol-gel processing and electrospinning technique. The products were characterized by scanning electron microscope （SEM）, Fourier transform infrared spectroscopy （FT-IR）, and photoluminescence （PL）. The results indicated that, Eu^3＋ was successfully embedded in the onedimensional hybrid nanofibers, and the PVP/Eu^3＋ hybrid nanofibers had favorable photoluminescence properties.     

室温以上磁制冷材料La(Fe1-xCox)11.7Al1.3化合物的研究

通过X射线衍射分析和超导量子干涉磁强计（SQUID）磁性测量,研究了Co替代Fe含量对居里温度在室温以上的磁制冷材料La（Fe1-xCox）11.7Al1.3（x=0.072,0.081）磁结构和磁性能的影响。La（Fe1-xCox）11.7Al1.3材料的居里温度随Co的含量增加而增加,La（Fe0.919Co0.081）11.7Al1.3的居里温度为311 K。当外场变化为1.9 T时磁熵变达到3.6 J·kg^-1·K^-1,RCP值为168.6 J·kg^-1,虽然它的磁熵变小于具有巨磁熵变的磁制冷材料,但是它在磁场为1.9 T时的制冷能力与这些材料相当。     

ON A CLASS OF METHOD FOR SOLVING PROBLEMS WITH RANDOM BOUNDARY NOTCHES AND/OR CRACKS(Ⅱ) COMPUTATIONS FOR BOUNDARY NOTCHES

This work is a continuation of the discussion of [1], On a class of method for solving problems with random boundary notches and/or cracks, (I) by C. Ouyang (Appl. Math. & Mech., vol. 1, No. 2, 1980). Here computations for boundary notches are made by using the theory and formulas presented in [1]. In the computation modification is also made for the boundary conditions in parametric plane in [1]. Numerical results for examples show that within ranges of parameter considered in the paper, for example L, the present method in quite workable in practical computations.     

Simultaneous determination of all-trans, 9-cis, 13-cis retinoic acid and retinol in rat prostate using liquid chromatography-mass spectrometry

Since retinoic acid (RA) and RA receptors are key developmental regulators during organogenesis, they might participate in the abnormal development of the prostate caused by early estrogen exposure. In order to test this assumption, a sensitive analytical method that can differentiate 9-cis, 13-cis, and all-trans RA in small tissue samples ( approximately 8 mg) is required. Since retinol is the metabolic precursor to RA, simultaneous quantification of retinol would also provide valuable information. Here, we report a liquid chromatography-mass spectrometry method for simultaneous determination of retinol and 9-cis, 13-cis, and all-trans RA in rat prostate. Mass spectrometric signal responses for RA were compared using positive ion atmospheric-pressure chemical ionization (APCI) and electrospray, as well as positive ion and negative ion APCI. Positive ion APCI was selected for all subsequent analysis for its better sensitivity, and to provide simultaneous determination of retinol and RA. Ventral prostate tissue samples were homogenized and extracted following simple protein precipitation without derivatization. Baseline separation of 9-cis, 13-cis, and all-trans RA standards was obtained by using a non-porous silica C18 column. Selected ion monitoring of the ions m/z 301 and m/z 269 was carried out for mass spectrometric quantitative analysis. The ion of m/z 301 corresponded to the protonated molecule of RA, whereas the ion of m/z 269 corresponded to loss of water or acetic acid from the protonated molecule of retinol or the internal standard retinyl acetate respectively. The method has a linear response over a concentration range of at least three orders of magnitude. The limit of quantitation was determined to be 702 fmol all-trans RA injected on-column. The method showed excellent intra- and inter-assay reproducibility and good recovery, and is suitable for analyzing RA and retinol in small tissue samples (approximately 8 mg).     

SITES OF PHOTODAMAGE in vivo and in vitro BY A CATIONIC PORPHYRIN

Abstract— Localization and photodynamic efficacy of a monocationic porphyrin (MCP) were assessed using murine leukemia cells in culture. This sensitizer localized at surface membrane loci and catalyzed selective photodamage to membrane structures. Although both cationic and hydrophobic, this porphyrin was not recognized by the multidrug transporter, which excludes many cationic agents from cells that express multidrug resistance. Photodynamic studies with the murine radiation-induced fibrosarcoma tumor model indicated moderate photosensitization of neoplastic lesions in vivo at 3 h, but not at 24 h after sensitizer administration. Pharmacokinetic studies indicate that plasma levels, not tissue levels were the major determinant of photodynamic therapy (PDT) response. Consistent with this observation, vascular damage and disturbances of tissue perfusion followed PDT. These effects were more pronounced in tumor-bearing skin than in normal skin. The therapeutic response to MCP appeared to be related mainly to secondary, probably vascular, effects.     

Fine structure and transition probabilities of the 2p 5 nl bound excited states of Ne atom

We present a semi-empirical calculational procedure for thep ⁵ nl bound excited states of rare gas atoms based on the use of an LS-dependent orbital for an excitednl electron outside a frozen Hartree-Fockp ⁵ core. The spin-orbit interaction is accounted for approximately using a localized Hartree potential. The contribution from the long-range core polarization is estimated by using a parametrized potential. A model potential is also introduced to represent partially the short-range multi-electron interactions for thep ⁵ np levels. The energy levels are calculated by diagonalizing the Hamiltonian matrix following anLS →jl transformation. The calculated fine structure of the Nep ⁵ ns,p ⁵ np,p ⁵ nd, andp ⁵ nf ¦ (jl)KJ〉 levels are in close agreement with the observed level splittings. The transition probabilities are also in agreement with earlier theoretical and experimental results.