IMAGING SCIENCE AND PHOTOCHEMISTRY

STUDY ON THE MECHANISM OF AUTO-SENSITIZED PHOTOOXIDATION OF HYPOCRELLIN

CHEN SHEN, ZHANG MAN-HUA, JIANG LI-JIN

1993, 11(2): 1-7. DOI: 10.7517/j.issn.1674-0475.1993.02.1

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In this paper the mechanism of auto-sensitized photooxidation of Hypocrellin was investigated in detail. Hypocrellin could autooxidized to a unstable peroxide, which could undergo two pathways of thermolysis; one was to yield the parent Hypocrellin and singlet oxygen, the other was to convert to the stable product. Singlet oxygen liberated from unstable peroxide was captured by active ¹O₂ acceptors. And the parent Hypocrellin inverted from unstable peroxide was illustrated by the dynamic measurement of absorption spectra. It was indicated through the quenching experiments that besides singlet oxygen mechanism other mechanisms may be parallely present in the auto-sensitized photooxidation of Hypocrellin.

KINETICS OF THE DEVELOPMENT INHIBITOR RELEASING COUPLER IN THE COLOR IMAGING PROCESS Ⅰ. THE REACTION OF DIR AND DIAR COUPLER WITH QDI IN GELATIN LAYER

ZHAO WEN-FANG, Mo YI-BO, XIA PEI-JIE, Hu PING, REN XIN-MIN

1993, 11(2): 8-13. DOI: 10.7517/j.issn.1674-0475.1993.02.8

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A conbination of flow-apparatus and a numerical model for simulating diffusion with a reaction on intersurface of droplets which were dispersed in a gelatin layer was employed for investigating the kinetic process of the reaction of dispersion DIR(Ⅰ)and DIAR(Ⅱ) coupler with QDI respectively in gelatin layer. The results showed that the kinetic curves obtained from both the experiments and the numerical model were in good agreement.This suggested that the reaction took place dominantly at the interface between droplets and gelatin-aqueous solution and that the reaction rate was dependent on the size of droplets, specific rate constant, concentrations of coupler in the organic medium and of QDI on the intersurface of droplets, which was also related to the diffusion coefficient of QDI in the gelatin layer. The specific rate constants of reaction of DIR(Ⅰ) and DIAR(Ⅱ)coupler with QDI were obtained respectively.

A STUDY ON THE PHOTOINDUCED CHARGE TRANSFER PROCESS OF TRIARYL-2-PYRAZOLINE COMPOUNDS

YAN ZHENG-LING, Wu SHI-KANG

1993, 11(2): 14-21. DOI: 10.7517/j.issn.1674-0475.1993.02.14

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In this work, the stationary photophysical behavior of triaryl-2-pyrazoline compounds with different substituted groups was studied. According to the results from the absorption spectra, fluorescence spectra of these compounds in various solvents with different polarity and their fluorescence quantum yields indicated that there are two mechanisms of photoinduced charge transfer process which are intramolecular conjugated and non-conjugated existing in the decay process. And the tendency of transfer reaction depends on the competition of these processes described above.

4-(4’-DIMETHYLAMINOSTYRYL)-BENZOPHENONE/ DIPHENYLIODNIUM SALT--A NEW KIND OF ELECTRON TRANSFER PHOTOSENSITIZATION SYSTEM FOR RADICAL PHOTOPOLYMERIZATION

Li JUN, LI MIAO-ZHEN, CHANG ZHI-YING, WANG ER-JIAN

1993, 11(2): 22-29. DOI: 10.7517/j.issn.1674-0475.1993.02.22

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A new photosensitizer, 4-(4’-dimethylaminostyryl)-benzophenone (MABP) has been synthesized and characterized spectrophotometrically. The MABP and diphenyliodonium salt(DPIO) combination system shows a good photoresponse at near UV and visible light regions. The photolysis of MABP/DPIO system occurs rapidly via electron transfer and leads simultaneously photo bleaching of MABP and cleavage of DPIO to generate phenyl radical. The photobleaching rate constant(k_b) determined was 30.7(mol^-1·L·s^-1). The photopolymerization of MMA was carried out in N₂ purged acetonitrile solution. The kinet-ical results obtained show that the polymerization rate is proportional to the concentration with exponents of 0.46, 0.32, and 1.0 for DPIO, MABP and MMA respectively. The considerable rate acceleration was obtained by adding thiol compounds. The photoinitiation mechanism was also discussed.

THE EFFECT OF TEMPERATURE AND IONS ON PHOTOCYCLE OF PURPLE MEMBRANE LB FILM

Hu KUN-SHENG, WANG AO-JIN, SUN YING

1993, 11(2): 30-35. DOI: 10.7517/j.issn.1674-0475.1993.02.30

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The decay rate of bacteriorhodopsin photocycle intermediate M412 in purple membrane LB film treated by ions and temperature was studied. The results showed that the decay rate turned fast with increaseing temperature. The decay of M₄₁₂s was inhibited by La³⁺ at low concentration, but by K⁺ at higher concentration. The decay of M₄₁₂s was accelerated by K⁺ and Ca²⁺ except La³⁺. The change of pH affected the decay rate of M412, When pH value reached 11, the decay rate of M₄₁₂s was much slower than that of normal pH value.

STUDY ON PHOTOCHEMICAL VALENCE ISOMERIZATION OF BICYCLO-[2.2.1]-2,3-DICARBOXY-2, 5-HEPTADIENE

MENG XIAN-JUAN, MING YANG-FU, FAN MEI-GONG

1993, 11(2): 36-39. DOI: 10.7517/j.issn.1674-0475.1993.02.36

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Photochemical valence isomerization of bicyclo [2. 2. 1] -2, 3 -dicarboxy -2, 5 -heptadiene (N) to quadrocyclo[2.2.1.0^2,3. 0^5,6]-2, 3 - dicarboxy heptane (Q) was performed by using polytetraphenyl-porphrine(P-TPP)as sensitizer. In addition, The Q can be easily converted into N under the presence of catalyst, Cobalt (Ⅱ) polytetraphenylpor-phrine (Co-P-TPP). The effects of the sensitizer and the catalyst on these isomerization reaction were tested. The comparation between the excited state energy of P - TPP and N indicated that photochemical valence isomerization may go by way of electron transfer from P-TPP to N. The support for the electron transfer machenism is fluorescence quenching of P-TPP by N.

STUDY OF PHOTOGRAPHIC PROPERTY OF GELATIN MACROMOLECULE Ⅰ. THE DETERMINATION OF METHIONINE SULFONE AND SULFOXIDE CONTAINED IN PHOTOGRAPHIC GELATINS

LI XUN, PENG BI-XIAN, XIAO YU-XIA, NI JING-HUA

1993, 11(2): 40-44. DOI: 10.7517/j.issn.1674-0475.1993.02.40

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Considering the great influence of methionine on the reducing capacity of gelatin it is of great importance to simultaneously determine the oxidized forms of Met(Metsox and Metson) contained in photographic gelatins. In present study, the complete analysis of amino acids, including Methioine, Methionine Sulfone and Sulfoxide contained in a range of gelatins, was performed with a Hitachi L-8500 Amino Acid Analyzer. Special attention had been paid to improve the test reproducibility and accuracy of this simultaneous determination method.It was shown that the Met contents are varied from sample to sample. Till now, almost all the gelatin samples contain Metson, and Metsox is found only in some of the samples involved.

STUDY OF PHOTOGRAPHIC PROPERTY OF GELATIN MACROMOLECULE Ⅱ. STUDY ON THE RELATIONSHIP BETWEEN MET, METSOX AND METSON CONTENTS IN GELATINS AND THEIR REDUCING CAPACITIES OF GELATINS

LI XUN PENG, BI-XIAN

1993, 11(2): 45-48. DOI: 10.7517/j.issn.1674-0475.1993.02.45

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The Met, Metsox and Metson contents in various gelatins were determined and corrected to the reducing capacity. The results showed that a gross linear relationship exists between Met contents and the reducing capacities of gelatins. It was first shown that an anti-parallel relationship exists between Metson contents and reducing capacities. In addition, a gross linear relationship between the sum of Met and Metsox contents and the reducing capacity was found as well. This discovery is of great significance not only for deepening our understanding the native of photographic property of gelatins, but also for improving quality and sustaining the homogeneity and constancy of gelatin products.

MODIFIED GELATIN (TYPE GGC) AS COAGULATING AGENT IN HIGH SPEED EMULSION

LIU XUAN-YA, PENG BI-XIAN

1993, 11(2): 49-55. DOI: 10.7517/j.issn.1674-0475.1993.02.49

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The problem how to raise the isoelectric point and salt effect of modified gelatin for coagulating emulsions of ammonical metnod has been attracting the attention of gelatin researchers. The present study is devoted to the following items:1) Synthesis of different modified gelatin with higher isoelectric point and better salt effect.2) Substitution degree evaluation.3) Iso-electric point determination with iso-electric focusing method.4) Coagulating and re-dispersing performances.5) Evaluation of recovery of silver halide and gelatin after coagulating.6) Sensitometric characteristics of emulsions prepared with GGC modified gelatin.Being as a coagulating agent of emulsion of ammonical method, GGC gelatin is superior to PA gelatin due to much less amount of acid required to start coagulation and higher sensitivity of the emulsion.

STUDY ON THE FLUORESCENCE PROPERTIES OF TWO SPECTRAL TYPES OF R-PHYCOERYTHRIN

HUANG YAN, QIN LI, ZHU JIN-CHANG, JIANG LI-JIN

1993, 11(2): 56-62. DOI: 10.7517/j.issn.1674-0475.1993.02.56

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There are two spectral types of R-phycoerythrin (R-PE) in red algae. One is the triple peak type R-PE with absorption maxima at 498, 540 and 565 nm. The other is the double peak type R-PE with absorption maxima at 498 and 565 nm, and an absorption shoulder at 540 nm.The fluorescence spectra and the lifetime of the two types of R-PE at various pH are studied. They are partly denatured at pH 3.6. The fluorescence intensity is reduced, and the lifetime is shortened. The fluorescence peak positions and the lifetime of triple peak type R-PE remain unchanged at pH6-13, but those of double peak type R-PE are various at pH 13. The fluorescence peak positions are shifted, and the lifetimes become longer. This phenomenon shows that there are certain differences in structures between the two types of R-PE.The concentration effects of the fluorescence spectra of R -PE are observed. The fluorescence peak positions are red shifted, the intensities are increased, then decreased, and the lifetimes become longer with the increase of protein concentrations. The fluorescence of R-PE is quenched by iodide ion. Meanwhile, the lifetime of R-PE tends to shortening. Stern-Volmer plot is obtained. The Stern-Volmer lines are not identical with different R -PE because of the different conformations they have.

KINETICS OF THE DEVELOPMENT INHIBITOR RELEASING COUPLER IN THE COLOR IMAGING PROCESS Ⅱ. THE EFFECT OF DIR AND DIAR COUPLER ON ESSENTIAL REACTIONS OF DYE FORMING PROCESS

ZHAO WEN-FANG, Hu PING, HE PEI-WEN, REN XIN-MIN

1993, 11(2): 63-68. DOI: 10.7517/j.issn.1674-0475.1993.02.63

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Based on the rate constants of the reaction of dye-forming coupler, DIR coupler and DIAR coupler with QDI respectively, the effects of DIR or DIAR on the essential reaction of dye image formation were investigated. The results showed (1) that DIR or DIAR coupler competes with dye-forming coupler for QDI, so it could control the diffusion range of QDI and decrease the rate of dye formation of the dye-forming coupler; (2) the inhibitor released from the reaction of DIR or DIAR coupler with QDI decreases the development rate of silver halide grams, so it controlled the formation rate of QDI. Both effects of DIR or DIAR made the dye cloud become finer than that without it. In addition, the effects of DIAR(Ⅲ), which has the same inhibiting group as DIR(Ⅱ), are greater than those of DIR(Ⅱ) owing to its greater rate constant with QDI.

A STUDY ON THE EMISSIVE CONFORMATION OF DIPHENYL PYRAZOLINE DERIVATIVES

YANG GUO-QIANG, Wu SHI-KANG

1993, 11(2): 69-75. DOI: 10.7517/j.issn.1674-0475.1993.02.69

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On the basis of the synthesis of pyrazoline derivatives with different stracture, the fluorescence quantum yields of these compounds have been measured in solvents with same polarity and different viscosities. Results indicated that, the rotation relaxtion of phenyl group attached to the 1-position of pyrazoline molecule possesses important significance. By means of the comparison of fluorescence intensity of these compounds in solvents with different polarities measured at fluidic and freezing conditions (at room temperature and 77 K), it can be proved that the emissive state of diphenyl pyrozoline compounds possesses a twisted conformation.

1993, 11(2): 76-81. DOI: 10.7517/j.issn.1674-0475.1993.02.76

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THE MECHANISM OF HIGH CONTRAST DEVELOPMENT

JI SU-XUE, MA FENG-YUN, CHEN SI-HAI, REN XIN-MIN

1993, 11(2): 82-85. DOI: 10.7517/j.issn.1674-0475.1993.02.82

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The development of emulsion layer is a gross process of the reduction of the emulsion grain population. Under the conventional development condition, the rate of density growth will give the information about the distribution of induction period among grains corresponding to the given exposure. The density difference among steps with different exposure depends on the relative rate of density growth of the steps, in turn depends on the different development behavior among grains. In the paper, the close relationship between the high contrast and the different development behavior among grains is discussed by taking two high contrast non-Lith systems as examples.

1993, 11(2): 86-86. DOI: 10.7517/j.issn.1674-0475.1993.02.86

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1993, 11(2): 87-87. DOI: 10.7517/j.issn.1674-0475.1993.02.87

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1993, 11(2): 88-88. DOI: 10.7517/j.issn.1674-0475.1993.02.88

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1993, 11(2): 89-92. DOI: 10.7517/j.issn.1674-0475.1993.02.89

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