PHOTOSENSITIZATION OF PYRIMIDINES BY 2-METHYLNAPHTHOQUINONE IN WATER: A LASER FLASH PHOTOLYSIS STUDY

2-Methylnaphthoquinone (MQ) has been excited in water with a 20 ns laser flash at 353 nm and the resultant transient species have been observed optically. Triplet-state MQ (³MQ) decays on a sub-microsecond time scale. It has been characterized in terms of its absorption spectrum and quantum yield. Rate constants have been measured for the decay of ³MQ in infinitely dilute solution, for self-quenching by ground-state MQ, and for reactions of ³MQ with oxygen, thymine, uracil, 6-methyluracil, and orotic acid. The interaction of ³MQ with pyrimidines involves charge transfer to give the pyrimidine cation radical and the MQ : anion radical. These reactions are discussed in relation to the mechanism of pyrimidine photooxidation sensitized by MQ.     

CTMAB对反相高效液相色谱-电化学检测法测定水中痕量酚类化合物的增敏、增稳作用

研究了阳离子表面活性剂CTMAB对高效液相色谱 -电化学检测法测定水中痕量酚类化合物的增敏、增稳作用。流动相中CTMAB的最佳浓度为 0 .80mmol/L。使用NucleosilC8色谱柱 (2 0 0mm× 4 .6mmi.d .) ,流动相为甲醇 - 0 .0 2 5mol/L邻苯二甲酸氢钾缓冲液 (体积比为 6 0∶4 0 ,pH =5 .0 ,含 0 .0 6mmol/LEDTA、0 .80mmol/LCTMAB)。该方法测定苯酚、4 氯苯酚、2 ,4 二氯苯酚、2 ,4 ,5 三氯苯酚的线性范围分别为 0 .10～ 15 .0 0、0 .15～ 12 .5 0、0 .15～ 2 2 .5 0、0 .30～ 5 0 .0 0 μg/mL ,检出限分别为 0 .0 0 8、0 .0 10、0 .0 16、0 .0 34μg/mL ,测定结果的相对标准偏差分别为 7.0 %、7.2 %、6 .0 %、7.0 % ,回收率分别为 4 8.0 %、80 .0 %、76 .0 %、85 .0 %。     

THE PHOTOCHEMICAL INTERACTION OF DEOXYRIBONUCLEIC ACID AND PROTEIN IN VIVO AND ITS BIOLOGICAL IMPORTANCE*,†

Summary When bacteria are irradiated with u.v. light there is a dose dependent decrease in the amount of DNA that can subsequently be extracted free of protein with detergent. This appears to be due to the crosslinking of the DNA with protein and the precipitation of the linked DNA when the denatured proteins are precipitated in the procedure used for the isolation of the DNA. The type of linkage between the DNA and the protein is unknown except that it resists the sequential attack of 2% sodium lauryl sulfate and 0.5 M KCI or 55% CsCI. The main evidence that the loss of DNA in vivo is due to the crosslinking of DNA and protein is that the crosslinking of DNA and protein can be demonstrated in vitro . X-rays do not crosslink DNA and protein in vivo , but acridine orange and visible light cause the crosslinking of DNA and protein both in vivo and in vitro .
By pulse labeling the DNA of bacteria with tritated thymine it can be shown that newly synthesized DNA is most sensitive to crosslinking and that this sensitivity shows a cyclic response keyed to the generation time of the bacteria. Under conditions of thymine starvation where the intrinsic sensitivity of the cells to killing by u.v. is markedly increased, there is a parallel increase in the sensitivity of the DNA of these cells to be crosslinked to protein. The similarity in the time sequence of these two events strongly suggests that the crosslinking may play an important role in the loss of viability following u.v. irradiation.     

A STUDY OF GEL STRUCTURE IN THE NONIONIC SURFACTANT / CETOSTEARYL ALCOHOL / WATER TERNARY SYSTEMS BY DIFFERENTIAL SCANNING CALORIMETER

Cetostearyl alcohol has been incorporated into cosmetic or pharmaceutial emulsions to give them an appropriate consistency and a long term stability. It is well known that cetostearyl alcohol forms a gel phase with a nonionic surfactant in an aqueous system, and the properties of the gel phase depend on several factors such as the ratio of fatty alcohols. The aim of the present paper is to investigate the effect of the structural difference of the lipophilic part of surfactants on the stability of the gel phase in the nonionic surfactant / cetostearyl alcohol / water ternary systems using differential scanning calorimeter.

It is concluded that the gel phase formed by the surfactant having the bended alkyl chain is more unstable than that formed by the case of     

差压式BOD测定装置测定工业废水中BOD

探讨了利用差压式BOD测定装置测定工业废水中BOD时影响其准确度的几个因素,并提出了相应的改进方法。     

VARIATION IN THE PHOTOCHEMICAL REACTIVITY OF THYMINE IN THE DNA OF B. SUBTILIS SPORES, VEGETATIVE CELLS AND SPORES GERMINATED IN CHLORAMPHENICOL*,†

Abstract— The chief photoproduct of thymine produced in u.v. irradiated (2537Å) vegetative cells of B. subtilis is the cyclobutane-type dimer while in spores very little of this dimer is produced (maximum yield 2·6 per cent of thymine) but a new photoproduct is produced in high yield (maximum of 28·4 per cent of thymine). This difference in photochemical response appears to be due, at least in part, to a difference in uydration of the DNA. The photochemistry of thymine in isolated DNA irradiated in solution is similar to that of DNA in irradiated vegetative cells, but differs markedly from that of isolated DNA irradiated dry. The yield of cyclobutane-type thymine dimer is much reduced in isolated DNA irradiated dry but a new photoproduct of thymine. is produced which is chromatographically similar to the spore photoproduct. The yield of this photoproduct, however, is never as great as that obtained in irradiated spores. The photochemistry of the DNA thymine of spores germinated in the presence of chloramphenicol is very similar to that of normal vegetative cells. Except for hydration, the physical state of the DNA is probably not otherwise altered by germination in the presence of chloramphenicol since DNA replication is prevented by the presence of chloramphenicol. These results are also consistent with the hypothesis that the unique photochemistry of spores is due, at least in part, to the hydration state of the DNA. The acid stability of the spore photoproduct is indicated by the fact that it is isolated from irradiated spores after hydrolysis in trifluoroacetic acid at 155°C for 60 min. It still contains the methyl group of thymine as judged by the fact that for a given dose of u.v. the same yield of photoproduct was obtained whether the spores were labeled with thymine-2–C-14 or -methyl-C-14. This photoproduct is stable to reirradiation (2537Å) in solution under condiditions where thymine dimers of the cyclobutane-type are completely converted back to monomeric thymine. On a column of molecular sieve material (Sephadex-G10), the spore photoproduct elutes in a region intermediate between the cyclobutanetype thymine dimers and monomeric thymine. Of the numerous compounds tested by paper chromatography, the spore photoproduct is most similar (but not identical) in several solvents to 5–hydroxyuracil and 5–hydroxymethyluracil. Our data do not allow us to decide if the product is a monomer or a dimer. Although the photochemistry of thymine in the DNA of spores differs markedly from that for vegetative cells, several lines of evidence make it seem doubtful that the enhanced resistance of spores to u.v. relative to that of vegetative cells can be explained solely on the basis of this difference in the photochemistry of DNA thymine.     

FT－IR和程序升温热谱技术研究Mo／HZSM－5催化剂的制备过程

采用ＦＴ－ＩＲ和程序升温热谱技术研究了Ｍｏ／ＨＺＳＭ－５催化剂的制备过程．结果表明Ｍｏ／ＨＺＳＭ－５样品在合适的温度下焙烧一定时间，Ｍｏ物种与ＨＺＳＭ－５分子筛的酸中心（主要是强酸中心）起作用，并且一部分Ｍｏ物种会迁移到分子筛孔道内．在外表面的Ｍｏ物种和在孔道内强酸中心作用的Ｍｏ物种，可能是对甲烷活化起作用的     

小波分析对奇异性检测用于滴定终点确定的研究

在分析化学领域中,利用数学判断法确定滴定终点,随着计算机的日益普及而备受关注。此文在介绍当前普遍采用的二进小波变换奇异性检测方法的基础上,提出基于多分辨率分析和连续小波变换两种奇异性检测方法,并应用于氢氧化钠对盐酸和磷酸滴定曲线判断终点的试验中,取得了良好的效果。     

EMULSION POLYMERIZATION AS A METHOD FOR THE DETERMINATION OF THE CRITICAL MICELLE CONCENTRATION OF SURFACTANTS OF LOW SOLUBILITY IN WATER +

Although a large number of methods are available for the determination of critical micelle concentrations many of these cannot be applied to the highest members of homologous series which are insufficiently soluble in water. The number of latex particles formed and consequently the rate of emulsion polymerization of such monomers as styrene which have only a very low solubility In water increase rapidly at the c.m.c. of the surfactant. When the surfactant is a salt which can be formed at the interface by dissolving the long-chain acid in the monomer and a slight excess of alkali in the water, observation of surfactant concentration at which this increase in particle number and polymerization rate takes place provides an experimental method for the determination of the c.m.c. which gives results in good agreement with expectation based on an extrapolation of results obtained by other methods on lower members of the series in the case of potassium docosanoate.     

纳米材料降低卷烟烟气粒相有害成分的研究靠

以干法和湿法分别将纳米材料Al2O2、SiO2、TiO2加入到卷烟烟丝和滤嘴中,研究了纳米材料的四种加入方式对卷烟烟气粒相中焦油、尼古丁生成量的影响。结果表明,纳米材料干法加入滤嘴,降低烟气中焦油、尼古丁效果最为明显,2.0-10.0mg/支的添加量可降焦油4.2-45.3%、尼古丁1.7-28.4%;干法加入烟丝,效果较为显著,添加5.0-25.0mg/支的纳米材料,降焦油4.2-32.2%、降尼古丁2.4-20.3%,其中纳米Al2O3的作用效果显著。纳米材料湿法添加到烟丝中,效果不明显;湿法加入到卷烟滤嘴丝束中,几乎没有效果。     

PERMEATION OF LYSOSOMAL MEMBRANES IN THE COURSE OF PHOTOSENSITIZATION WITH METHYLENE BLUE AND HEMATOPORPHYRIN: STUDY BY CELLULAR MICROSPECTROFLUOROMETRY

Abstract— The photodynamically-induced liberation of lysosomal enzymes using ß-galactosidase as marker for the lysosomal enzymes has been studied by microspectrofluorometry on mouse L cells. Similar studies have been carried out using N-acetyl-ß-D-glucosaminidase as marker for the lysosomal enzymes of human fibroblasts. The high sensitivity of the fluorescence detection makes it possible to use 4-methylumbelliferyl substrates for the enzymes contained in a single cell. Methylene blue and hematoporphyrin readily incorporate into both cells and upon excitation, sensitize lysosomal membrane damages, leading to enzyme release accompanying strong morphological changes.     

PHOTOSENSITIZATION BY ANTITUMORAGENTS–6. PRODUCTION OF SUPEROXIDE RADICAL AND HYDROGEN PEROXIDE DURING ILLUMINATION OF DIAMINOANTHRACENEDIONES IN THE PRESENCE OF NADH IN AQUEOUS SOLUTIONS: AN EPR STUDY

Abstract— Photosensitizing capabilities of anthracenedione anticancer agents to oxidize NADH in aqueous solutions have been studied by EPR and spin trapping techniques. It is demonstrated that 1,4-diamino substituted anthraquinones, like mitoxantrone and ametantrone, do not photosensitize NADH oxidation while 1,5- and l,8-bis[[(diethylamino)ethyl]amino]anthraquinones do, undergoing simultaneous one-electron reduction to their semiquinone radical forms upon illumination with visible light. In aerated aqueous solutions the reaction leads to the production of superoxide ion and hydrogen peroxide.     

Fe在丝光沸石骨架中取代位置的DFT研究

用密度泛函理论(DFT)方法研究了Fe同晶取代进入丝光沸石骨架后可能存在的位置,并确定了与电荷平衡质子结合的氧位置.能量分析表明Fe在丝光沸石骨架中最容易进入T2和T4位;当Fe分别在T2和T4位时,电荷平衡质子与O2和O10结合的可能性最大.     

原子吸收光度法测定水中六价铬的新探索

研究用巯基棉为吸附富集剂,定量测定水中六价铬的新方法。     

QUANTUM YIELD OF PRODUCTION OF SINGLET MOLECULAR OXYGEN (xδg) IN AQUEOUS DISPERSIONS OF SMALL UNILAMELLAR LIPID VESICLES. A TIME-RESOLVED NEAR-IR PHOSPHORESCENCE STUDY*,†

The quantum yield of formation and kinetic behaviour of O2(1 delta g) in D2O dispersions of small unilamellar vesicles (SUVs) of dipalmitoyl phosphatidylcholine were studied by time-resolved detection of near-IR phosphorescence. At a SUV concentration of 26 nM, O2(1 delta g) is not quenched by the vesicles. It diffuses quickly through the lipid bilayer and a partition equilibrium of O2(1 delta g) between the lipid bilayer and the buffer is attained before decay occurs. In this equilibrium situation O2(1 delta g) is mostly located in the buffer phase, which permits the determination of absolute quantum yields for O2(1 delta g) production, phi delta, by comparison of the luminescence in the dispersions with that in neat D2O. The maximal phi delta values for the sensitizers incorporated in the SUV bilayer were 0.47 +/- 0.09 for the dipyridyl complex of zinc(II) phthalocyanine (ZnPc), 0.35 +/- 0.08 for porphycene, and 0.36 +/- 0.08 for 2,7,12,17-tetra-n-propylporphycene. These values are equal to those in neat organic solvents but lower than those previously obtained in SUVs by using chemical trapping agents. The high degree of organization of the environment around the sensitizers does not influence their efficiency of producing O2(1 delta g). While no concentration dependence is observed for ZnPc (at least up to a local concentration of 20 mM in the bilayer), phi delta for both porphycenes significantly decreases above a local concentration of 4 mM in the bilayer. This result is expected in view of previous observations on the concentration dependence of other photophysical parameters of the porphycenes in such microheterogeneous media.     

INTERMEDIATES IN THE PHOTOCONVERSION OF FUNCTIONAL PHYTOCHROME IN FERN SPORES OF Dryopteris-I DEMONSTRATION AND QUANTITATIVE CHARACTERIZATION OF THE PHOTOCHROMIC SYSTEM Pr⇔ Ii700USING NANOSECOND-LASER PULSES*,†

Abstract— Spores of Dryopteris paleacea and D. filix-mas are positively photoblastic with an optimum in the action spectrum around 665 nm. Light is perceived by phytochrome and the relationship between germination and mole fraction of the far-red-absorbing form of this pigment, P_fr, was investigated with saturating irradiations between 662 and 747 nm under low-fluence-rate conditions. These control irradiations establish a proportion of the total phytochrome, P,_tot, as P_fr with P_fr/P_tot–φ at equilibrium. These φ -values were calculated according to data for native oat phytochrome (Kelly and Lagarias, 1985, Biochemistry 24, 6003) and the spectral characteristics of the interference filters. With this method a linear relationship could be found between φ and germination from 2 to 70% for D. paleacea and from 2 to 90% for D. filix-mas, if probit germination was plotted vs probit φ This correlation formed the basis of investigating the phytochrome photoconversion by dye-laser pulses of 380 ± 30 ns under high-fluence-rate conditions, and thus to test quantitatively the impact of the photoreversibility of intermediate reactions of the photoconversion and the red-absorbing form of phytochrome, P_fr on the final P_fr-level. Spore germination was initiated by a single-laser pulse in the range from 592 to 700 nm. The most effective wavelengths were 649 and 660 nm in both species, and at saturation maximal germination (ca. 50%) was obtained from 592 to 665 nm for D. paleacea or ca. 60% germination from 592 to 670 nm for D. filix-mas. Both saturation levels correspond to a ø-value between 0.40 and 0.45. This significantly diminished photoconversion is a consequence of the high-fluence-rate conditions during the laser pulse which establishes the photochromic system between P_r and a set of very early intermediates, Iⁱ_700, (= P_r? Iⁱ₇₀₀). This system can be described by the extinction coefficients of P_r and the intermediates Iⁱ₇₀₀, and by the quantum yields, 4,φ for the forward and reverse reactions as φ If φ is calculated, assuming a quantum yield of 1:1 for both reactions and with the extinction coefficients of P_r and Iⁱ_7(l() (= lumi-R) given by Eilfeld and Riidiger (1985, Z. Naturforsch. 40c , 109), significantly higher values are calculated for / as compared to φ found in the control experiments. These results can be explained either: (i) with a quantum yield ratio φ_pr-φ1700: φ_1700φpr=1:1 and an assumed additional dark reaction leading from Iⁱ₇₀₀ or later intermediates back to P_r: or (ii) with a quantum yield ratio φ_{pr φ 1700}: φ_{1700 φpr}=1:2. In this case all Iⁱ₇₀₀ have to relax to P_fr. In this case all Iⁱ₇₀₀ have to relax to P_fr.     

THE MECHANISM OF DELAYED LIGHT PRODUCTION BY PHOTOSYNTHETIC ORGANISMS AND A NEW EFFECT OF ELECTRIC FIELDS ON CHLOROPLASTS*,‡

Abstract— Green plants, after illumination, emit light at times far too long to be fluorescence. This delayed light is closely connected with the process of photosynthesis and seems to be one of the few ways of studying the first steps in that process. In this paper we argue that there are at least 3 or maybe 4 mechanisms producing delayed light. (1) The delayed light in the range of 1–100 msec seems to come from the recombination of electrons and holes. The photosynthetic unit must absorb 2 quanta for this process. (2) At longer times the delayed light can come from thermal fluctuations lifting an electron from the level of ferredoxin to that of chlorophyll. The unit need only absorb 1 light quantum for this kind of delayed light. (3) Similarly, a part of the long-time delayed light comes from the untrapping of holes. (4) A part of the delayed light emitted at times longer than a few minutes seems to involve molecular oxygen. Finally, we shall describe a new phenomenon involving the effect of electric fields on chloroplasts, that we feel will be helpful in understanding the untrapping mechanisms of delayed light production.     

PHASE TRANSITIONS IN COLLOIDAL SYSTEMS PART I: REFRACTOMETRIC STUDY OF THE BINARY SYSTEM SDS+WATER OR PENTANOL-1+WATER AND THE TERNARY SYSTEM WATER+SDS+PENTANOL-1 AT 298.15 K.

The monophasic ranges for the binary systems water+SDS and water+pentanoM and for the ternary system water+SDS+pentanoM has been studied by means of refractametric experiments at 298 K.

The curves of refractometric index versus the composition of the system, has shown the existence of several transitions labeled successive critic micellar concentrations. These transitions are detected by a change of the variation of the refractive index.

We have evidenced the very importance of the pentanol-1 in these amphiphilic solutions, acting as a surfactant or as an oil according the concentration.

For these systems it is passible to better understand the phase inversion phenomena.

At last, we present the phase diagram indicating the concentration range of the different microstructures.     

DISTORTIONS IN AMPHIBIAN DEVELOPMENT INDUCED BY ULTRAVIOLET-B ENHANCEMENT (290–315 NM) OF A SIMULATED SOLAR SPECTRUM

Abstract— Effects of increased intensity of UV-B radiation (290–315nm) on the systemic development and viability of boreal toad tadpoles were studied. When compared with animals exposed to UV-B deficient radiation of similar irradiance, tadpoles exposed to UV-B enhanced radiation displayed (1) abnormal development of the presumptive cornea, (2) areas of hyperplasia in the integument, (3) an anomalous, concave curvature of the spine, and (4) increased mortality. Daily exposure to photoreactivating radiation (> 315nm) following UV-B insult mitigated the potentially lethal damage to the tadpole population.     

STUDIES ON THYMINE-DERIVED UV PHOTO-PRODUCTS IN DNA—II. A COMPARATIVE ANALYSIS OF DAMAGE CAUSED BY 254 NM IRRADIATION AND TRIPLET-STATE PHOTOSENSITIZATION

Abstract— From the rates of cyclobutyl dipyrimidine (Pyr < > Pyr) formation and the ratio of inactivation of transforming or phage DNA caused by direct (254 nm) or sensitized (1.0 M acetone, 313 nm; 0.02 M acetophenone, 334 nm) irradiation, we conclude that Thy < > Pyr and Cyt < > Pyr are equally lethal, and that they are repaired with equal efficiency by the host cell. Not all the damage formed by photosensitized irradlation can be photoenzymatically repaired, especially when acetone is the sensitizer. We found no compelling evidence for photosensitized interstrand cross-links or sensitizer-DNA addition products for the fluence range used in these studies (< 10⁶ Jm^-2); moreover, strand breakage can account for only a part of the non-photorepairable damage. We suggest that a fraction of the damage may be due to Pyr < > Pyr isomers other than the cis, syn type usually formed in native DNA by far-UV light.