Within a simple theoretical model we demonstrate analytically the effect of intrinsic localized modes such as breathers on nonlinear optical properties. We have earlier observed enhancement of optical nonlinearities in ab initio numerical simulations of ®nite polyenes, speci®cally C40H42. We also discuss experimental implications of our results. # 2001 Elsevier Science B.V. All rights reserved....

Improved nonlinear organic chromophores of varying conjugation length with either thiobarbituric acid or 3-dicyanomethylene-2,3-dihydrobenzothiophene-1,1-dioxide (FORON® Blue) acceptors have been synthesized and investigated for their nonlinear optical properties. Very large quadratic hyperpolarizabilities b(22v; v, v) have been found, up to 25,700 3 10248 esu at l 5 1.91 mm. In a guest–host po...

Clethramycin from Streptomyces malaysiensis DSM4137, and mediomycins (produced together with clethramycin from Streptomyces mediocidicus), are near-identical giant linear polyenes apparently constructed from, respectively, a 4-guanidinobutanoate or 4-aminobutanoate starter unit and 27 polyketide extender units, and bearing a specific O-sulfonate modification at the C-29 hydroxy group. We show h...

The biosynthesis of the pyrrolyl moiety of the fungal metabolite rumbrin originates from pyrrole-2-carboxylic acid. In an effort to produce novel derivatives with enhanced biological activity a series of substituted pyrrole-2-carboxylates were synthesised and incubated with the producing organism, Auxarthron umbrinum. Several 4-halo-pyrrole-2-carboxylic acids were incorporated into the metaboli...

Fungal infections are emerging now a days causing wide spectrum of diseases in humans and animals mostly affecting patients with immunodeficiencies or chronic illness. As such we can see that rise fungal infection suffering from Covid-19. It has become measure challenge for clinicians to treat invasive as there is only limited classes antifungal agents available. So this causes the over use whi...

The potentiation of the antiviral activity of acyclovir [9-[(2-hydroxyethoxy)methyl]guanine] by polyene macrolide antibiotics has been studied as a function of the macrolide structure. The 12 polyenes chosen for this study represented the major structural groups of these antibiotics and induced in mammalian cells repairable membrane alterations or irreversible cell damage. The potentiating acti...