LEAKAGE OF 86Rb+ AFTER ULTRAVIOLET IRRADIATION OF Escherichia coli K-12

Abstract— Stationary phase cultures of a DNA repair proficient Escherichia coli K-12 strain showed a release of intracellular material as assessed by three different methods (260 nm absorption; [methyl-³H]thymidine leakage and ⁸⁶Rb⁺ leakage) after broad-band (Black-Light Blue) near-UV radiation but not after far-UV (254 nm) radiation. As a control response for membrane damage to cells, this leakage of intracellular material was also determined by each method after mild-heat (52°C) treatment of E. coli K-12. An action spectrum for the release of ⁸⁶Rb⁺ from E. coli K-12 after irradiation with monochromatic wavelengths, from 254 to 405 nm, is also presented. The action spectrum for lethality (F₃₇ values) obtained for this strain, shows that leakage of ⁸⁶Rb⁺ occurs at fluences equivalent to or slightly less than fluences causing inactivation at wavelengths above 305 nm. In contrast, at wavelengths below 305 nm, leakage of ⁸⁶Rb⁺ from irradiated cells can be induced but only at fluences significantly greater than was required to cause cell inactivation. These results indicate, therefore, that near-UV radiation can induce a damaging effect on the cell's permeability barrier which may be significant in causing the death of the cell, whereas the effect is not significant in causing the death of cells by far-UV radiation where DNA damage is known to be the main cause of lethality.     

A surfactant hydroperoxide

The micellar hydroperoxy surfactant $\text{n}$-C₁₆H₃₃$\text{N}\text{+}$(CH₃)₂CH₂CH₂OOH, CF₃SO₃^? cleaves $\text{p}$-nitrophenyl acetate ～500 times faster than the corresponding hydroxy surfactant, and ～20,000 times faster than lyate ion at pH 8.     

The crystal and molecular structures of the compounds [(η5-C5H5)Fe(CO)2]2(CH2)n, where 0 n = 3 and 4

The crystal stuctures of [(η⁵-C₅H₅)Fe(CO)₂]₂(CH₂)_n, n = 3 and 4, have been determined.[(η⁵-C₅H₅)Fe(CO)₂]₂(CH₂)₃: a = 21.20, b = 10.39, c = 7.88Å, β = 101.6°, U = 1699ų, C2/c, Z = 4, R = 0.059, 1036 observed data.[(η⁵-C₅H₅)Fe(CO)₂]₂(CH₂)₄: a = 7.63, b = 10.54, c = 21.87Å, β = 96.4°, U= 1748ų, P2₁/c, Z = 4, R = 0.051, 1418 observed data.In each compound the iron atoms are joined by simple chains of sigma bonded CH₂ groups. Bond lengths are similar in both: mean Fe-CO 1.75, C-O 1.15, FeC(cp) 2.11, FeCH₂ 2.08, (cp)CC(cp) 1.41, CH₂CH₂ 1.55Å. The (CH₂)₃ compound retains a 2-fold axis of symmetry in the crystal. The (CH₂)₄ compound has no imposed symmetry, but closely approximates centrosymmetry. The effects of molecular symmetry on the IR spectrum between 2100 and 1900 cm^-1 are discussed. The¹³C and₁H (270 MHz) NMR spectra in solution are shown to be consistent with the structures found crystallographically.     

Di- and tri-nuclear osmium carbonyl chloride complexes: x-ray structures of Os2(CO)8Cl2 and Os3(CO)12Cl2

Summary Os₂(CO)₈Cl₂ (1) is orthorhombic P2₁2₁2₁ witha=9.3599(9),b=9.879(2),c=16.014(3), V=1480³, D_c=3.03 Mgm^–3 for Z=4. Structure solved by Patterson methods. Final R=0.038, R_w=0.038 [w=(²F)] for 1270 observed reflections and 141 parameters. Os₃(CO)₁₂Cl₂ (2) is monoclinic C2/m witha=12.105(3), b=10.612(3),c=8.798(1) , =117.02(2)°, V=1006³, D_c=3.22 Mgm^–3 for Z=2. Structure solved by Patterson methods. Final R=0.036, R_w=0.037 (w=(²F)^–) for 821 observed reflections and 75 parameters.Complex(1) has an osmium-osmium single bond 2.897(1), with the chloride ligands in equatorial positions,(2) has a linear triosmium chain with osmium-osmium single bonds 2.893(1) and the chloride ligands occupy equatorial sites on the terminal osmium atoms. Both(1) and(2) are isostructural with their osmium carbonyl iodide analogues.     

Holes in the probability density of strongly colored noise driven systems

A qualitative change in the topology of the joint probability densityP(,x), which occurs for strongly colored noise in multistable systems, has recently been observed first by analog simulation (F. Moss and F. Marchesoni,Phys. Lett. A 131:322 (1988)) and confirmed by matrix continued fraction methods (Th. Leiber and H. Riskin, unpublished), and by analytic theory (P. Hänggi, P. Jung, and F. Marchesoni,J. Stat. Phys., this issue). Systems studied were of the classx=–U(x)/x+(t,), whereU(x) is a multistable potential and (t, ) is a colored, Gaussian noise of intensityD, for which =0, and (t) (s)=(D/)exp(–t–s/). When the noise correlation time is smaller than some critical value ₀, which depends onD, the two-dimensional densityP(,x) has the usual topology [P. Jung and H. Risken,Z. Phys. B 61:367 (1985); F. Moss and P. V. E. McClintock,Z. Phys. B 61:381 (1985)]: a pair of local maxima ofP(,x), which correspond to a pair of adjacent local minima ofU(x), are connected by a single saddle point which lies on thex axis. When >₀, however,the single saddle disappears and is replaced by a pair of off-axis saddles. A depression, or hole, which is bounded by the saddles and the local maxima thus appears. The most probable trajectory connecting the two potential wells therefore does not pass through the origin for >₀, but instead must detour around the local barrier. This observation implies that successful mean-first-passage-time theories of strongly colored noise driven systems must necessarily be two dimensional (Hänggiet al.). We have observed these holes for several potentialsU(x): (1)a soft, bistable potential by analog simulation (Moss and Marchesoni); (2) a periodic potential [Th. Leiber, F. Marchesoni, and H. Risken,Phys. Rev. Lett. 59:1381 (1987)] by matrix continued fractions; (3) the usual hard, bistable potential,U(x)=–ax ²/2+bx ⁴/4, by analog simulations only; and (4) a random potential for which the forcingf(x)=–U(x)/x is an approximate Gaussian with nonzero correlation length, i.e., colored spatiotemporal noise, by analog simulation. There is a critical curve ₀(D) in the versusD plane which divides the two topological behaviors. For a fixed value ofD, this curve is shifted toward larger values of ₀ for progressively weaker barriers between the wells. Therefore, strong barriers favor the observation of this topological transformation at smaller values of . Recently, an analytic expression for the critical curve, valid asymptotically in the small-D limit, has been obtained (Hänggiet al.).This paper will appear in a forthcoming issue of theJournal of Statistical Physics.     

Anil-Synthese 22. Mitteilung über die Herstellung von Styryl-und Distyryl-Derivaten des Pyridins

Preparation of Styryl and Distyryl Derivatives of Pyridine 2,4-, 2,5- and 2,6-Dimethylpyridines react with anils of aromatic aldehydes in the presence of dimethylformamide and potassium hydroxide to yield the corresponding distyrylpyridines (‘anil synthesis’). Under the same reaction conditions (4-methylstyryl)pyridines are converted to (stilbenylvinyl)pyridines. Similarly, the Schiff's base derived from pyridine-3-carbaldehyde and p-chloroaniline on treatment with methyl- and p-tolyl-substituted aromatic heterocycles gives the corresponding (heteroaryl-styryl)pyridines, whereas with the Schiff's bases derived from pyridine-2- and -4-carbaldehyde side reactions, such as dimerization followed by disproportionation predominate.