THE ROLE OF SOLAR ULTRAVIOLET RADIATION IN 'NATURAL' WATER PURIFICATION

Abstract— The concentration of Escherichia coli in the input and output of a tertiary wastewater system (4 lagoons) has been monitored over an 11 month period. The integrated flux of biologically active solar ultraviolet (UV) radiation was measured during this period. By also determining (1) the effective temperature in the system, (2) the growth rate of E. coli at the effective temperature, (3) the penetration of the solar UV into the lagoons, (4) the dose-response relation for killing of E. coli by UV and (5) the retention time of water in the system, it is possible to compare the 'die off' expected from solar UV exposure to the actual 'die off' observed for different batches of water.
The observed killing of E. coli was quite close to the values calculated, considering the numerous factors involved. Solar UV light would thus seem to be a very important factor in the natural purification of water. Because each successful species must possess characteristics (physiological or behavioral) which provide adequate resistance to solar UV, the ecological role of solar UV radiation has not been widely appreciated.     

ULTRAVIOLET SOLAR RADIATION IN THE HIGH LATITUDES OF SOUTH AMERICA

Abstract Measurements of the UV solar irradiance are available from Ushuaia, Tierra del Fuego during the spring and summer seasons of 4 consecutive years beginning in 1989. In addition, column ozone amounts derived from satellite-based measurements exist for this location over the entire period from 1980 through 1991. Monthly mean column ozone over Ushuaia shows a general decline over the observing period, and a large day-to-day variability exists within a given month. Ozone amounts for the years 1980 through 1986 combined with a model of radiative transfer provide a climatological baseline against which to interpret the more recent ground-based irradiance data. We focus on monthly mean noontime irradiances integrated over 5 nm wide spectral bands near 305 nm and 340 nm, respectively. Measurements in the 340 nm band show that cloudiness has a large influence on both the absolute monthly mean irradiances and their interannual variability. For example, during December the 340 nm band irradiance varied from approximately 50% of the clear-sky value in 1992 to 65% in 1991. When the influence of cloudiness is removed, most of the months show irradiances in the 305 nm band that are larger than predicted from the climatological ozone amounts. The largest percentage enhancement occurred in October 1991 when the irradiance exceeded the baseline by 56%. The largest absolute irradiances occur in December, where the measurements range from 5.8% below the baseline in 1991 to 31% above in 1990.     

辐射交联高聚物的溶涨与弹性性能的修正关系式

在辐射交联过程中,Charlesby假定交联度(及裂解度)与剂量成线性关系,导出了交联高聚物的溶涨与弹性性能关系式(1)及(2)。     

甲基丙烯酸磺酸基己酯钠盐的共聚合、聚合及其均聚物的抗凝血性能

研究了甲基丙烯酸6-磺酸基己酯钠盐与甲基丙烯酸甲酯、甲基丙烯酸β-羟乙酯及甲基丙烯酸正己酯的共聚合,并测定了它在水及二甲亚砜中的聚合速度关系式。聚甲基丙烯酸6-磺酸基己酯钠盐的抗凝血性能在一定分子量范围内相差不多。     

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.     

WAVELENGTH DEPENDENCE OF THE FORMATION OF SINGLE-STRAND BREAKS AND BASE CHANGES IN DNA BY THE ULTRAVIOLET RADIATION ABOVE 150 nm

The wavelength dependence of the formation of two types of DNA damage, single-strand breaks and base changes, was investigated in the UV region from 150 nm to 254 nm using superhelical closed circular (form I) colicin El DNA with synchrotron radiation. Single-strand breaks were measured by agarose gel electrophoresis as a direct conversion of form I DNA to form II DNA (open circular). Base damages were defined as sensitive sites to a crude extract of endonuclease from Micrococcus luteus. They also were estimated using the same conversion, from form I to form II after the DNA was treated with endonuclease. The fluence-effect relationship could be fitted by a simple exponential function for both types of damage. Action spectra were constructed based on the reciprocal of the 37% fluence. The action spectrum for strand breaks increased rather monotonically over three decades from 254 nm to 150 nm in a logarithmic scale, while that for base damages showed a breaking point at 190 nm, being relatively flat above 190 nm. The characteristics of the action spectra are compared with the absorption spectra of the DNA and its main chain moiety calculated on the basis of data on calf thymus DNA and synthetic polynucleotides. Our main conclusions are (1) that the majority of single-strand breaks were induced by the absorption of photon in the sugar-phosphate group in the vacuum-UV region and (2) that the base changes were induced equally well by absorption in the vacuum-UV and in the far-UV region.     

MEASUREMENT METHOD AND PHYSICAL MODEL OF VSC CONDUCTIVITY AND ITS APPLICATIONS IN CONDUCTING POLYMERS

Method of VSC (Voltage Shorted Compaction)can be used to determine the intrinsic temperature dependence ofconductivity ofpolycrystalline compaction. The experimental conditions and technical key for preparation of VSC device and its physical model as well as its applications in conducting polymers are discussed in detail.     

聚乳酸类生物降解性高分子材料研究进展

本文综述了近年来乳酸类合成生物降解材料的合成及应用研究进展。     

EFFECTS OF SOLAR RADIATION ON DEVELOPMENT IN THE CELLULAR SLIME MOLD, Dictyostelium discoideum

–The effect of solar radiation on development was studied in two strains (wild type N04 and axenic AX2) of the cellular slime mold, Dictyostelium discoideum. In both strains early development was retarded by solar radiation and amoebae exposed for >200 min never developed into mature sorocarps. Overheating can be excluded as a mechanism for inhibition since the organisms were exposed in a temperature-controlled growth chamber. The most effective component seems to be UV-B radiation (while UV-A has a smaller inhibitory effect) as shown by cutting off shorter wavelength radiation using WG filters.     

THE IMPORTANCE OF THE MICROENVIRONMENT SURROUNDING A CHROMOPHORE IN DETERMINING ITS SPECTROSCOPIC BEHAVIOR*

Se pone especial énfasis en la importancia del microambiente de un grupo como factor determinante del comportamiento fotoquímico, emisión y dicroismo circular de móleculas biológicas. Los ejemplos dados incluyen la fotoquímica de la ribonucleasa, la dependencia de las propiedades luminiscentes de amino acidos aromáticos con la temperatura, y el comportamiento espectroscópico de los dinucleótidos.     

MEASUREMENTS OF SOLAR MIDDLE ULTRAVIOLET RADIATION IN A DESERT ENVIRONMENT

Abstract— In this study measurements are reported that were carried out between August 1983 and December 1985 on the solar middle ultraviolet radiation (UVB-280-320 nm) in Kuwait (29.5°N). These measurements are based primarily on polysulfone film detectors. Comparative measurements were also made on a Robertson-Berger meter and a spectroradiometer. The results reported include the daily variation of the solar UVB between 11:30 a.m. and 12:00 noon over the year, the diurnal variation, as well as the amount of UVB as a function of the receiving angle with the horizontal.
Based on these data the polysulfone films were found to be reliable and inexpensive detectors, giving results similar to those of the R-B meter. The diurnal variation of the solar UVB was found to vary as sin2q, where q is an angle that corresponds to the time since sunrise compared to the sunrise-sunset interval times 180. An empirical equation is developed that gives the maximum UVB as a function of the time of day and day of year. A correlation is determined of the polysulfone readings with the spectroradiometric and the R-B meter measurements. The solar insolation was found to be independent of the receiving angle with the horizontal in the winter months and develops into a cosine dependence in the summer months.     

EFFECTS OF SOLAR RADIATION ON MOTILITY IN: Stentor coeruleus

The effects of solar radiation on the motility of the colored ciliate, Stentor coeruleus, have been assessed as a photodynamic model system for hypericism. The organism has been found to be extremely sensitive to solar radiation–a few minutes of unfiltered radiation suffice to arrest motility and decrease the velocity of movement. Removing UV-B and UV-A radiation prolongs the tolerated exposure times. From the present study, the mechanisms of the photodynamic action in S. coeruleus and in hypericin-sensitized reactions have not been resolved in terms of Type I and II mechanisms.     

CHOICE OF COATINGS FOR THE OPTICAL ELEMENTS IN THE IRRADIATION SYSTEM OF VACUUM-ULTRAVIOLET RADIATION ABOVE 50 nm

The spectral throughput of a vacuum-ultraviolet irradiation system at the SOR-RING facility was examined with various combinations of aluminum-and gold-coated optical elements in a 2.2-m modified Wadsworth monochromator. We found that the optimum was a combination of an aluminum-coated collimating mirror, concave grating, and plane deflecting mirror, and a combination of a gold-coated collimating mirror, concave grating and an aluminum-coated plane deflecting mirror in the wavelength regions 190-110 nm and 110-50 nm, respectively.     

THE PHOTOLYSIS OF TRYPTOPHAN WITH 337.1 nm LASER RADIATION

Abstract— Aqueous solutions of L-tryptophan were photolyzed by exposure to 337.1 nm radiation from a pulsed nitrogen laser. These data were compared with results for the 290 nm conventional-source photolysis of tryptophan. The progress of photolysis was monitored by fluorescence analysis of tryptophan. UV absorption spectroscopy, HPLC, TLC, and proton NMR spectroscopy. The loss of Trp was observed to be first order for 290 nm photolysis but of mixed order for 337.1 nm photolysis. Five photolysis products were detected by TLC analysis, including: N-formylkynurenine. kynurenine, tryptamine (detected after 290 nm photolysis but not 337.1 nm photolysis) and two unknown products. The tryptophan-containing peptides N-acetyl-tryptophanamide (NATA) and tryptophylglycine (Trp-Gly) were also observed to photolyze upon 337.1 nm laser radiation demonstrating that this phenomenon is not restricted to free tryptophan monomer.
Since Trp is not ordinarily thought to absorb U V radiation at wavelengths as long as 337.1 nm. a number of experiments were performed in an effort to determine the mechanism of photolysis at this wavelength. Evidence is presented which indicates that the 337.1 nm laser photolysis of Trp does not result from two photon absorption, dielectric breakdown, or other laser-specific processes. Instead. it is concluded that this photolysis results either from a very weak absorption tail extending to 337.1 nm in tryptophan itself or from a reaction involving an impurity sensitizer which absorbs the 337.1 nm radiation. The sensitizing impurity. if present, could not. however, be removed by preparative HPLC and could not be detected by TLC or fluorescence analysis.     

PENETRATION OF SOLAR UV IRRADIATION IN COASTAL LAGOONS OF THE SOUTHERN BALTIC SEA AND ITS EFFECT ON PHYTOPLANKTON COMMUNITIES

Abstract Direct measurements of solar UV irradiance at the surface and in the water column were made in several coastal lagoons near the islands of Hiddensee and Rügen in spring and summer 1993 using an internally frosted quartz sphere at the end of a 10 m quartz fiber cable connected to a double monochromator spectroradiometer. The measurements showed a nearly uniform vertical distribution of the absorption coefficient in the whole water column due to effective mixing, shallow depths and little temperature and salinity density stratifications. There was an increase in the absorption coefficient at 310 nm from 5 m⁻¹ in the outer lagoons to 12 m⁻¹ in the open inner lagoons and up to 29 m⁻¹ in the inner lagoons without water exchange with the Baltic Sea as a result of different amounts of UV-absorbing substances such as yellow substance (Gelbstoff) and seston. Depending on the specific concentration of the absorbents, the solar UV-B irradiance decreases to 1% after penetration into the water column between 0.2 m (inner lagoons without water exchange), 0.4 m (inner lagoons with water exchange), and 1 m (outer lagoons), whereas UV-A penetrates on the order of several meters. As phytoplankton populates the top layers of the water column it may be affected by increased solar UV irradiation even in these turbid coastal waters.     

军事计量工作的重要性及其发展方向

通过介绍军事计量学的概念、作用和特点并结合美国军事最新导弹防御系统、近代局部战争中显现的信息化先进武器装备等实例,简要分析了军事计量工作的发展动态、方向和前景.     

CHLOROMETHYLATION OF POLYMERS MADE FROM TECHNICAL DIVINYLBENZENE AND PROPERTY OF THE CHLOROMETHYLATED POLYMERS

1. INTRODUCTIONMacroporous polymers of technical divinylbenzene are often used as polymeric adsorbents for adsorptive separation. These resins may be advantageous compared to other polymeric adsorbents due to the high specific surface area and high porosity. However, the ability of these resins to adsorb polar compounds is very weak because the resins are non-polar and the values of the swelling capacity in aqueous solution are relatively low, and thus these resins are limited for adsorpti…     

CHLOROMETHYLATION OF POLYMERS MADE FROM TECHNICAL DIVINYLBENZENE AND PROPERTY OF THE CHLOROMETHYLATED POLYMERS

The goal this paper was to reveal the feasibility of chloromethylation of polymers made from technical divinylbenzene so as to introduce functional groups into polymeric adsorbents.Forthis study,the factors,that effect the chloromethylation reaction,such as the pore structure of the polymer,the ratio of the reactants to catalyst,the reaction temperature and reaction time and so on were investigated.and the pore structure and property of the chloromethylated polymers were studied.The results showed that polymers of technical divinylbenzene could be chloromethylated successfully,and the adsorptive property of the chloromethylated resin was different from that of the initial resin.     

CALCULATING THE MOLECULAR INTERNAL ROTATING STERIC FACTOR OF POLYMERS BY THE RADIATION CROSSLINKING METHOD

In this paper, calculating the molecular internal rotating steric factor of polymers by the radiation crosslinking method is studied and a relationship between the molecular internal rotating steric factor (σ) and crosslinking parameter βis established~([1]) by taking account of the effect of polymer chain flexibility on βvalue, σvalue of polymer obtained by this method is in agreement with that given with other method.