Flow and reactive transport in porous media induced by well injection: Similarity solution

The authors study concentration profiles of solutes undergoingequilibrium absorption in the vicinity of a water well. Forthe case of a contamination event, the limit problem of vanishingwell radius, which is of self-similar nature, is analysed indetail. Existence, uniqueness, and qualitative properties ofsolutions of the corresponding ordinary differential equationsare shown. Some numerical examples are also presented.     

BIOLOGICAL ACTIVITIES OF PHTHALOCYANINES-X. SYNTHESES AND ANALYSES OF SULFONATED PHTHALOCYANINES

Abstract— Synthetic methods to obtain selectively sulfonated metallo phthalocyanines are compared. Both condensation and direct sulfonation procedures lead to mixtures of mono- to tetrasulfonated products which are resolved by reverse phase liquid chromatography in buffered aqueous-methanol. The proportion of sulfonated derivatives is examined as a function of the starting reagents in the case of the condensation method, and as a function of the temperature and reaction time in the case of the direct sulfonation procedure. The number of sulfonate groups per phthalocyanine molecule is determined by oxidative degradation of the phthalocyanine ring followed by quantitative chromatographic analysis of the sulfophthalamide and phthalamide fragments.     

RADICAUX LIBRES INDUITS PAR L''ACTION DU RAYONNEMENT ULTRAVIOLET SUR CERTAINS CONSTITUANTS DE L''ACIDE DEOXYRIBONUCLEIQUE

The action of ultra violet rays of 260 nm on aqueous solutions of bases, nucleosides and nucleotides of DNA at 77°K is studied by electron spin resonance. It is shown that the free radicals observed are similar, with a few noteworthy exceptions to those induced by X-rays, under the same conditions of temperature, in the solid state. Contrary to what might be excepted on the basis of the results obtained by X-rays, the variation in the yield in paramagnetic centres in each sequence studied does not seem to be important.     

ETUDE PAR RESONANCE PARAMAGNETIQUE ELECTRONIQUE DE LA PHOTOSENSIBILISATION DES ACIDES AMINES PAR LA PROFLAVINE

Abstract— –The photosensitization of amino acids by proflavine is studied using the technique of electron spin resonance spectroscopy. The analysis of the line shape as a function of the incident microwave power (both in the presence and absence of oxygen) and the dependence of the numbers of free radicals on the intensity of the incident light allow one to suggest that two types of radicals are formed. One is formed by a biphotonic process, the nature of the radicals being the same as in the case of ionising radiation, while the other is probably the RO₂ radical formed as a result of photodynamic action.     

SURFACE STRUCTURE DETERMINATION BY STM vs LEED

Scanning tunneling microscopy has been developed, among other applications, into a powerful surface structural tool. Over time, it has become more apparent that theoretical modeling of the STM image is often necessary to reliably extract atomic positions. We here review recent advances in this direction and illustrate with several examples that geometrical information is mixed not only with electronic structure information and corresponding tip properties, but also with tunneling effects like interference between multiple tunneling channels.     

TEMPERATURE DEPENDENCE OF CHLOROPHYLL FLUORESCENCE FROM THE LIGHT HARVESTING COMPLEX II OF HIGHER PLANTS

Abstract— Chlorophyll fluorescence spectra of LCHII, the light harvesting complex of photosystem II, have been recorded in the aggregated and trimeric forms for a range of temperatures from 293 to 4 K. At least five long-wavelength emitters in the 682–702 nm region with different temperature dependencies were found in the spectra of the aggregates. At 293 K the yield of LCHII trimers was higher than aggregates by a factor of 4, but, upon lowering the temperature, a fluorescence rise was observed which was much stronger for LCHII aggregates than for LCHII trimers, so that at 4 K their yields were comparable. The implications of these data in terms of the function of LCHII are discussed.     

The Temperature Field or Electric Potential Around Two Almost Touching Spheres

The temperature field or electric potential around two equal,perfectly conducting spheres which are almost touching is studiedusing the method of matched asymptotic expansions. The dominant"outer" approximation of the calculational scheme applies inthe narrow gap between the spheres while the "inner" approximationapplies in the remaining volume outside the gap. The purposeof the calculation is to investigate the properties of certainsingularities whose existence has been indicated by earliersolutions of the Laplace equation around two spheres. For example,the electrostatic forces acting on the spheres or the heat fluxbetween them can become infinite when the spheres touch. Theexplicit forms of the singularities are found and used to assessthe accuracy of earlier solutions. In the appendix the correspondingtwo-dimensional problems for almost touching cylinders are analysed.     

SPECTROSCOPIC AND ORIENTATIONAL PROPERTIES OF CHLOROPHYLL a AND CHLOROPHYLL b IN LIPID MEMBRANES

Abstract
Linear dichroism and fluorescence depolarization measurements on chlorophyll a and chlorophyll b molecules incorporated into macroscopically oriented multibilayers of the plant lipid digalactosyldiacylglycerol (DGDG) are presented. The results are combined with measurements of fluorescence anisotropy to obtain both the order parameters describing the orientational statistics and the directions of the absorption and emission transition moments in the frame of the molecules. The problem presented by the overlapping nature of the absorption and emission bands is overcome by determining the fluorescence depolarization at the two maxima of the emission spectrum.     

The Free-boundary Problem for Gravity-driven Unidirectional Viscous Flows

If a layer of viscous fluid drains steadily under gravity, whilein contact with an upward-moving vertical cylinder of a generalcross section with boundary C_B its velocity w(x, y) satisfiesa Poisson equation w_xx+w_yy = g/v = constant. There are two boundaries,the given curve C_B on which w takes a prescribed constant value,and a free boundary C_p marking the edge of the layer, whoseshape we wish to determine. In order to do this, we need twoboundary conditions on C_F; one is the zero-stress conditionw/n = 0, and we assume that the other is that w is constantaround C_F. The latter condition is shown to be equivalent toa requirement that the volume flux in the layer is maximal.The properties of the resulting free-boundary problem are discussed,and numerical solutions obtained for some special cases. Forexample, a solution for the case when C_B is a 270? corner showsthat the layer thickness at the corner is reduced to 76% ofthe thickness on the flat part of the boundary. The presentanalysis is relevant to industrial coating problems, such asedge effects in continuous galvanizing of sheet steel.     

PHOTOCONTROL OF ANTHOCYANIN SYNTHESIS IN TOMATO SEEDLINGS: A GENETIC APPROACH*

The photocontrol of anthocyanin synthesis in dark-grown seedlings of tomato (Lycopersicon esculentum Mill.) has been studied in an aurea (au) mutant which is deficient in the labile type of phytochrome, a high pigment (hp) mutant which has the wild-type level of phytochrome and the double mutant au/hp , as well as the wild type. The hp mutant demonstrates phytochrome control of anthocyanin synthesis in response to a single red light (RL) pulse, whereas there is no measurable response in the wild type and au mutant. After pretreatment with 12 h blue light (BL) the phytochrome regulation of anthocyanin synthesis is 10-fold higher in the hp mutant than in the wild type, whilst no anthocyanin is detectable in the au mutant, thus suggesting that it is the labile pool of phytochrome which regulates anthocyanin synthesis. The au/hp double mutant exhibits a small (3% of that in the hp mutant) RL/far-red light (FR)-reversible regulation of anthocyanin synthesis following a BL pretreatment. It is proposed that the hp mutant is hypersensitive to the FR-absorbing form of phytochrome (P_fr) and that this (hypersensitivity) establishes response to the low level of P_fl. (below detection limits in phytochrome assays) in the au/hp double mutant.