ELECTRON SPIN RESONANCE OF MELANIN FROM HAIR. EFFECTS OF TEMPERATURE, pH AND LIGHT IRRADIATION

Abstract— The variation with temperature, pH and light of the ESR signal of hydrated melanin powders from Japanese black hair has been studied. An explanation of the results is proposed on the basis of quinhydrone type complexes and of acid-base equilibria of melanin and its semiquinone radicals. During exposure to light of wavelengths 254–600 nm, both stable and unstable radicals have been observed. The action spectrum for the formation of stable melanin radicals has been determined.     

等电点沉淀法分离毛发水解物L-酪氨酸

本文叙述了以毛发水解液为起始原料,利用等电点沉淀法,在不影响提取L-胱氨酸的同时,提取了L-酪氨酸的工艺过程。得率为0.45％,产品质量达到日本药典标准,工艺简单易行     

EFFECT OF HUMIDITY ON PHOTOINDUCED ESR SIGNAL FROM HUMAN HAIR

Abstract— Human red hairs, equilibrated at 79.8%, 58.0%, 32.3% humidity and at dry conditions, were irradiated with UV-visible (Λ > 290 nm) light. ESR intensity of the photo-induced transient free radicals was measured, at room temperature, as a function of time during and after exposure to light. Photoenhancement was found to be most pronounced in 79.8%-humidity conditioned hair and least in dry hair. The lifetimes of the transient free radicals in these samples were measured as 360s (79.8%), 180s (58.0%), 140s (32.3%), and 50s (dry). The gradual increase in lifetime as a function of humidity conditions was attributed to an increasing number of decay rates of the centers varying from fast to slow, the slow ones being unable to decay unless the fast ones do. This process is best described by a stretched exponential time function, I ( t ) = I _oexp[-( t/t _o)^α].     

ON SOME POSSIBILITIES OF PROTECTING CELLS FROM DAMAGING EFFECTS OF ULTRAVIOLET IRRADIATION

Abstract. The possibility of increasing the cell resistance to short-wave u. v. rays has been investigated with some chemicals. Ciliated epithelium cells of gills of pearly mussel Unio crassus Phillipsson have been shown to become more resistant after treatment with 0^.25–0.50 per cent solutions of calcium chloride during 24 hr or by 0.001– 0.001 per cent solutions of 2-benzyl-benzimidazole during 3–7 days or by 0.0001 per cent solution of 5–6-di-methyl-benzimidazole during 7 days. When irradiated with u. v. light (λ=2537 Å) these cells survive for a longer time than irradiated control cells.     

THE GENERATION OF HYDROGEN PEROXIDE BY THE UVA IRRADIATION OF HUMAN LENS PROTEINS

Abstract— The water-insoluble proteins from aged human lens are known to contain protein-bound chromophores that act as UVA sensitizers. The irradiation of a sonication-solubilized, water-insoluble fraction from human lenses (55–75 years) with UVA light (1.5 kj/cm², λ > 338 nm) caused an oxygen-dependent photolysis of tryptophan, not seen when either α-crystallin or lysozyme were irradiated. The suggested requirement for active oxygen species was consistent with a linear increase in hydrogen peroxide formation, which was also observed. A final concentration of 55 µM H₂O₂ was attained, with no H₂0₂ being detected in either dark-incubated controls or in irradiated samples of native proteins. The UVA-dependent H₂O₂ formation was increased 50% by superoxide dismutase (SOD) and abolished by catalase, arguing for the initial generation of superoxide anion. A linear photolysis of histidine and tryptophan was also seen; however, the addition of SOD or SOD and catalase had no effect on the photolytic destruction of either amino acid. Superoxide dismutase increased the oxidation of protein SH groups implicating H₂O₂, but SOD and catalase caused a decrease in SH oxidation only at later time periods. The direct addition of H₂O₂ to a water-insoluble sonicate supernatant fraction caused only a slight oxidation of SH groups, but this was increased four- to eight-fold when the protein was denatured in 4.0 M guanidine hydrochloride. Overall, the data suggest a UVA-dependent oxidation of protein SH groups via H₂O₂ generated within the large protein aggregates of the water-insoluble fraction. These data also provide a mechanism for oxidation of the sulfur-containing amino acids in vivo—a process that is known to accompany the formation of age-onset cataracts.     

EFFECTS OF EXCITED-STATE PROTON TRANSFER ON THE PHOSPHORESCENCE OF TYROSINE-PHOSPHATE COMPLEXES

Abstract Phosphate anions quench the fluorescence of tyrosine at room temperature as a result of an excited-state proton transfer. At 77 K in frozen solutions the fluorescence of tyrosine is still quenched by phosphate anions but the phosphorescence emission is enhanced. No tyrosinate phosphorescence is detected. A mechanism is proposed to explain these results: excited-state proton transfer from tyrosine to phosphates is followed by intersystem crossing in tyrosinate anions with subsequent back-transfer of the proton in the triplet state.     

COMPARISON OF PHOTOTRAP COMPLEXES FROM CHROMATOPHORES OF RHODOSPIRILLUM RUBRUM, RHODOPSEUDOMONAS SPHEROIDES, AND THE R-26 MUTANT OF RHODOPSEUDOMONAS SPHEROIDES*

Abstract— After dissolution of the membrane structure of chromatophores from Rhodospirillum rubrum, Rhodopseudomonas spheroides , and the R-26 mutant of Rhodopseudomonas spheroides , active phototrap complexes from each have been purified by a column electrophoresis procedure. Phospholipids and transition metals were well separated from the phototrap complex in all three systems. The purified R. rubrum phototrap complex retained a full complement of antenna bacteriochlorophyll and carotenoid pigments which had nearly the same absorbance spectra as in the intact cell, and which delivered absorbed light energy to the phototrap with just as high efficiency as in the intact cell. Sodium dodecyl sulfate (SDS) disc gel electrophoresis using Tris buffer showed that these preparations often contained only two prominent polypeptides of 30,000 ± 2000 and 12,000 ± 4000 mol. wt., and a lesser amount of a third polypeptide of 21,000 ± 2000 mol. wt.
The phototrap complexes prepared from the wild type and the R-26 mutant of R. spheroides were similar, in that a partial separation from antenna pigments occurred during column electrophoresis. Both complexes had prominent polypeptides of 24,000 ± 2000 and 21,000 ± 2000 mol. wt., but no polypeptide of 30,000 mol. wt remained after electrophoresis. A third major polypeptide occurred with a mol. wt. of about 12,000 but seemed identifiable with an incompletely separated antenna pigment fraction. The phototrap complex prepared from the R-26 mutant had a typical reaction center spectrum.
In the case of wild type R. spheroides purification, two distinct protein-pigment complexes separated. Although the absorbance of the bacteriochlorophyll and carotenoid pigments were little changed from those of the in vivo system, different polypeptides in the two fractions were observed by SDS disc gel electrophoresis; only one fraction seemed to be intimately related with the phototrap complex.     

全固态铅离子选择性电极测定人发中微量铅

提出了用全固态铅离子选择性电极测定人发中微量铅的方法。在 1.5 g·L- 1抗坏血酸 1g·L- 1三乙烯四胺 0 .0 5mol·L- 1高氯酸钠 ,pH 4.85 .5的条件下 ,采用格氏作图法可准确测定人发中微量铅。方法简便、准确度高 ,回收率 95 % 10 6% ,相对标准偏差小于 5 .3 %。     

γ—射线辐照对聚乙烯单晶结构的影响

采用混合晶红外光谱、X-射线衍射及小角散射、差示扫描量热法研究γ-射线辐照对溶液生长聚乙烯单晶的影响,表明γ-射线辐照在单晶的规则折叠区也引起了不可忽视的结构缺陷或畸变。     

微波溶样-火焰原子吸收光谱法测定人发中锌

锌是人体内主要且必需的微量元素之一。头发作为人体的一部分 ,其发锌含量的多少 ,可以不同程度的反映一个人的营养和健康水平。微波溶样技术是当前世界上最先进的样品预处理技术之一 ,将这一技术应用于发锌含量的测定 ,建立起系统的微波溶样 -火焰原子吸收分析方法 ,获得了满意的结果。该方法的运用对于临床诊断和营养调查有非常重要的作用。1　仪器与试剂AA- 670 1原子吸收分光光度计 (日本岛津公司 )MK- 1型微波溶样炉 (上海新科微波技术应用研究所 )锌标准储备液 :50 0 mg· L-1(中国预防医学会 )锌标准使用液 :取标准储备液 1 .0 0 m…     

火焰原子吸收光谱法测定人发中微量元素前处理方法研究

对火焰原子吸收光谱法测定人发中量元素的前处理方法进行了研究,发现用HNO3:HC1O4=8:1进行消化,三蒸水直接稀释定容,结果满意.用干法灰化,温度不宜高于600℃.     

THE EFFECTS OF IRRADIATION ON THE THERMAL PROPERTIES OF SEMI-CRYSTALLINE POLYAMIDES

Irradiation crosslinking of semi-crystalline polyamides was performed by high energy electronswith various dosages. It is known that the melting behavior of the polymers after irradiation is acomplex phenomenon. In company with the wide angle X-ray diffraction and DSC data of irradiatedand unirradiated polyamides it is possible to develop the local order and perfection of the crystallinitiesslightly which resulted from introduction of intermolecular crosslinking in amorphous region, incl-uding in amorphous-crystalline interface and crystalline defect regions due to irradiation. It canbe explained that slight increase of melting temperature (T_m) and heat of fusion (△H_f) with increasingdosage for both of higher crystallinity nylon 4 and nylon 6. For irradiated lower crystallinity nylons,in contrast, the T_m and △H_f decrease obviously with increasing dosage. In this case, radiation cross-linking "freeze in" the pre-existing morphology, and then the prevention for reorganization duringheating is a dominant effect. The T_m from the second melting for all of the samples were depressed,corresponding with Flory theory. Therefore the crosslinks imposed on the molecules restrainedthe molecular mobility, and that not only depresses the crystallinity but also increases the imperfec-tion of crystallites when the radiated polymer melted and then recrystallized. These are also reflectedin the depression of heat and entropy of fusion as well as the appearance of double melting peakson the DSC thermograms.     

THE EFFECT OF LASER IRRADIATION ON THE RELEASE OF bFGF FROM 3T3 FIBROBLASTS

Studies have shown that low-level laser irradiation increases the proliferation of fibroblasts in cell culture. The mechanism of action is unknown. Basic fibroblast growth factor (bFGF) is a multifunctional polypeptide that has been detected in most tissues and which supports cell proliferation and differentiation. The purpose of this study was to determine whether laser irradiation (660 nm) can stimulate production of bFGF from fibroblast cells in cell culture. Our study showed that fibroblasts irradiated with laser energy at 2.16 J/cm² demonstrated increased cell proliferation and enhanced production of bFGF, whereas fibroblasts irradiated with laser energy at 3.24 J/cm² neither demonstrated increased cell proliferation or an enhanced release of bFGF as compared to the control group. These results provide direct evidence that the proliferation of fibroblasts as a result of stimulation by low level laser irradiation may be associated with the autocrine production of bFGF from fibroblasts.     

STERIC EFFECTS IN REACTIONS OF METAL COMPLEXES. THE LIGAND SUBSTITUTION PROCESSES

Abstract

A model for the calculation of the activation energy for the ligand substitution processes in the metal complexes, occuring in the polar solvents, is suggested. The model takes into account sharp repulsion between the ligands at small distances. The structure of the transition state is analysed depending on the sharp repulsion distance between the ligands, symmetry factor α, and position of the incoming group with respect to the outgoing group (cis or trans). It is shown that for certain values of the parameters cis-substitution may be preferable than trans-substitution.     

EFFECTS OF UV-B IRRADIATION ON PHOTOMOVEMENT IN THE DESMID, Cosmarium cucumis

Abstract Monochromatic UV-B irradiation affects neither the absorption nor the fluorescence of the bulk pigments in the desmid Cosmarium cucumis but it impairs photomovement of these organisms at fluence rates which are not higher than the ambient level of solar UV-B irradiation. Photoaccumula-tions and phototaxis are strongly inhibited especially at wavelengths ≤ 300 nm while photodispersal at higher white light fluence rates is hardly affected by supplementary UV-B. This effect has important consequences for the growth and survival of populations in their natural environment: these photosyn-thetic organisms utilize photomovement to find and stay in areas of suitable visible light fluence rates. The UV-B component of solar irradiation both impairs the strategy of the organisms to find a suitable position and the escape mechanism by which the cells move out of areas with too strong white illuminances which photooxidize the bulk pigments and bleach the population within a few days.     

THE EFFECT OF pH ON THE FLUORESCENCE OF COMPLEXES OF HUMAN SERUM ALBUMIN AND BOVINE SERUM ALBUMIN WITH BILIRUBIN

Abstract— Fluorescence studies as a function of pH clearly show that the environment and conformation of bilirubin bound to human serum albumin (HSA) are quite different than those for binding to bovine serum albumin (BSA). The visible fluorescence of the bilirubin-BSA complex is maximal at the extremes of pH; in contrast, the bilirubin-HSA complex fluorescence is at a maximum, near physiological pH.     

CHARACTERISTICS OF THE CHEMILUMINESCENCE FROM THE BLOOD PLASMA OF A NORMAL HUMAN POPULATION

Oxygen-dependent chemiluminescence was detected from human blood plasma. The intensity of the chemiluminescence increased about three-fold under oxygenation and decreased almost to the background (zero) level under a nitrogen atmosphere. The blood plasma from a sample (n = 100) of donors was tested to determine the variability of several properties of the chemiluminescence in a normal population. No statistically significant difference in blood plasma chemiluminescence between genders was found, but there was a slight increase in luminescence intensity with age. However, the results were found to be dependent on a number of other factors, such as diet, smoking and the length of time between the donor's last meal and the sampling of the blood. Some of the trends in the results coincide with similar trends in the plasma lipoprotein levels and thus support the suggestion that the chemiluminescence arises from the decomposition of lipid hydroperoxides. These factors must all, therefore, be taken into account when using chemiluminescence as an indicator of illness.     

月季花红色素的提取及稳定性的研究

一．引言月季，别名月月红，月季花（ＲｏＳａＣｈｉｎｅｎｓｉｓＪａｃｑ），属蔷薇科，蔷薇属，从每年的３月到１０月蓓蕾续放，开花不绝，现广泛栽培，主要分布于河北、陕西、山西等地。月季花主要成分为萜醇类化合物［１］，花、根及叶均可入药，内服可治妇女病，外用...     

聚合物结晶成核剂作用的表征方法的比较和研究

用聚合物的等速降温过程的结晶温度，等温结晶过程的半结晶时间（ｔ１／２）或结晶速度常数（Ｋ），结晶过程的晶核密度或球晶尺寸大小和聚合物结晶成核界面自由能（σσｅ或σｅ）大小等方法描述了碳酸钙、对苯二甲酸、苯甲酸钠对聚丙烯成核结晶过程的影响．通过对不同方法的比较，结果表明不同方法是从不同角度来反映助剂对聚合物成核结晶过程的影响，聚合物结晶温度的高低和等温结晶过程的半结晶时间或结晶速度常数是描述聚合物整体结晶速度的参数；而聚合物结晶过程中晶核密度或结晶完了时聚合物球晶尺寸，和聚合物结晶成核界面自由能大小与聚合物的成核难易程度直接相关，是判断聚合物结晶成核速度的方法．但不同方法之间存在一定的相关性，所以用不同方法测定的结果之间有较好的可比性，可根据具体条件选用一种方法．多种方法的配合使用可以较全面的了解成核剂的作用．