PHOTOSENSITIZATION BY DRUGS: NALIDIXIC AND OXOLINIC ACIDS

Abstract— The antibacterial drugs, nalidixic acid and oxolinic acid, have been tested as photosensitizers in aqueous solution using 365 nm UV light. Absorption and fluorescence spectra indicate that intramolecular hydrogen bonding stabilizes the unionized form of these compounds in the pH region2–4. The ability of the unionized species to sensitize photooxidation by the type II (singlet oxygen) mechanism was found to be lower than when these drugs were ionized. Comparison withquinoline–3-carboxylic acid and the methyl esters of nalidixic and oxolinic acids emphasised the significance of the hydrogen bonding in relation to the excited state properties. Unionized nalidixic acid undergoes photolysis more readily than the ionized form, apparently by a free radical mechanism, while oxolinic acid is more stable.     

Resonances Introduced by Discretization

This paper examines the effect of spatially discretizing thenon-linear equation chosen to model the integro-differential equations governinginterfacial vortex sheets. Here H is the Hilbert transform and is a spatial average. It is shown numerically and analyticallythat small-amplitude travelling-wave solutions of the discretizedmodel equation are subject to instabilities whose growth rateis proportional to the amplitude and depends in a complicatedway on the number of mesh points per wavelength. The mechanismof the instability is shown to be a resonance not present inthe continuous system and present in the discrete system becausethe frequency of waves with wavelength equal to twice the meshspacing is zero.     

注入信号对自由电子激光的影响

本文中讨论了一个注入信号对自由电子激光的影响,找到了自由电子激光脉冲破裂的原因,和抑制脉冲破裂的方法。 关键词：     

自由电子激光器的稳定脉冲解

本文用自由电子激光器经典理论的数值解法,给出一组稳定脉冲解。计算表明,这种解只能在特定条件下获得,只要满足这些条件,解的形状与初始脉冲形状无关,对于微小扰动是稳定的,并保持传播不变。 关键词：     

Optimal Recovery in the Finite-Element Method, Part 1: Recovery from Weighted L2 Fits

Finite-element methods lead to approximations that are optimalor near-optimal in an associated energy norm. The consequentialproblem of recovering point values of the solution or its derivativesis addressed in this paper and its companion. A general frameworkis adopted, based on the seminal paper of Golomb & Weinberger(1959), which brings together several ideas such as superconvergence,local averaging and defect correction. Detailed results aregiven for piecewise constant and 2 linear approximations inone dimension: recovery from weighted L² fits is treated here,and from weighted H¹ fits in Part II     

A COMPARISON OF SERUM KINETICS AND TISSUE DISTRIBUTION OF PHOTOFRIN II FOLLOWING INTRAVENOUS AND INTRAPERITONEAL INJECTION IN THE MOUSE

Abstract Although hematoporphyrin derivative (HPD) and its 'purers' variety Photofrin II are the most widely used tissue sensitizers in both clinical and experimental photodynamic therapy (PDT), quantitative studies of tissue distribution have been few. We have extracted and measured Photofrin II in several organs of the normal mouse including those of relevance to urological practice. In view of the reported heterogeneities in the distribution within tissues of various cytotoxics when administered intraperitoneally. we have compared results for Photofrin II given by this route with those for intravenous injection. Although both routes of administration gave equally consistent results, differences in absolute tissue concentration as a function of time after injection were found for several but not all tissues. Furthermore, the porphyrin accumulated following intravenous administration seemed to contain more of the non-polar photodynamically active component than that accumulated following the intraperitoneal route. We attempt to explain these differences by reference to published data on porphyrin binding to serum proteins.     

Relativistic chemical shielding: formally exact solutions for one—electron atoms of maximum total angular momentum for any principal quantum number

Analytical solutions have been derived for the chemical shieding of one-electron atoms in states of maximum total angular momentum (j = n -1/2). The variation of terms connecting states of different angular momentum is discussed as a function of the quantum numbers, k(= n), j and m the magnetic quantum number, and of Z, the atomic number.