Logarithmic Capacity and Renormalizability for Landing on the Mandelbrot Set

We study renormalizability of external angles of the Mandelbrotset M. Estimates are made of the logarithmic capacity of setsof angles that are infinitely renormalizable with a specificsequence of periods, using a substitution due to Douady. Theseshow that many of the infinitely renormalizable rays do landon M, which provides further evidence in support of the conjecturethat M is locally connected.     

Reversed-phase liquid chromatography of elastin peptides

Soluble fragments of elastin are frequently present in biological tissue in small amounts. Because of their hydrophobic character, these peptides are not well resolved by a number of conventional techniques. However, their separation should be possible by reversed-phase chromatography. A wide range of columns, gradients and solvents were evaluated. Two systems are described. One was a C18 liganded silica column eluted isocratically by gravity flow. Some degree of size fractionation was achieved with larger peptides being eluted with methanol and smaller ones with isopropanol. The second system uses a pressurized elution from another C18 ligand column. A concave gradient of trifluoroacetic acid-acetonitrile with a decreasing acetonitrile concentration was optimal. Similar resolution of peptides produced by a variety of digestion methods was obtained with the lower-molecular-mass peptides eluting in the middle of the gradient.     

Simultaneous thermal/mass spectral investigations of ammonium exchanged zirconium phosphates and zirconium arsenates

The half- and fully-ammonium ion exchanged forms of α- and γ-zirconium phosphates and of α-zirconium arsenate have been prepared. Their modes of thermal decomposition were studied by thermal methods of analysis, including simultaneous DTA/mass spectrometry. The samples heated to various temperatures were also characterized by X-ray diffraction analysis together with IR spectroscopy. The loss of water and ammonia of the various exchanged samples is compared in terms of the changes taking place in the layer lattice upon heating. The use of DTA/MS for a system involving water and ammonia as volatiles is demonstrated     

PHOTODYNAMIC ACTION OF CHEMICALLY RELATED FLAVONES

Abstract— Flavone, polyhydroxyflavones (apigenin, fisetin, kaempferol, luteolin, myricetin, quercetin, resokaempferol and robinetin), polymethoxyflavones and acetylated and benzylated flavones were tested for photodynamic activity using Tetrahymena pyriformis T as the test organism. Among these compounds, polymethoxyflavones showed the highest order of activity, followed by flavone and then flavone derivatives with OH and OCH₃ groups. Resokaempferol was the only active polyhydroxyflavone, the remainder being inactive such as the benzyl-derivative. The methoxyl group in the 5–position and an increase in number of methoxyl groups from one to three in the phenolic portion of the flavonoid tended to decrease photodynamic activity. Tetrahymena killed photodynamically by polymethoxyflavones were morphologically altered by blister-like blebs. Polymethoxyflavones showed the lowest cytotoxicity and the greatest photodynamic activity among those flavonoids tested. The majority of the favonoids in this series have absorption spectra in the 320–370 nm region.     

Studies on nucleophilic additions at bridging vinyl ligands in triosmium clusters

The bridging vinyl clusters [HOs₃(CHCHR)(CO)₁₀] (R = H, Ph, or n-Bu) react with PMe₂Ph to give the zwitterionic adducts [HOs₃(CHCHRPMe₂Ph)(CO)₁₀] which contain μ₂-alkylidene ligands. The adducts are not formed so readily when R = Ph or n-Bu but most readily when polar solvents are used. All three CHCHR complexes add cyanide ion irreversibly to give the anionic clusters which were isolated as [N(PPh₃)₂][HOs₃(CHCHRCN)(CO)₁₀]. There is infrared evidence for the addition of various other anions. Acid reverses the addition of methoxide but HCl reacts with the cyanide adduct [HOs₃(CHCH₂CN)(CO)₁₀]^? to give [HOs₃Cl(CO)₁₀] and EtCN. No evidence for nucleophilic addition at [HOs₃(PhCCHPh)(CO)₁₀] was obtained.     

Finite Element Methods for a Model for Full Waveform Acoustic Logging

A model is defined to simulate the propagation of waves in aradially symmetric, isotropic, composite system consisting ofa fluid-filled well bore ^f through a fluid-saturated poroussolid ^p. Biot's equations of motion are chosen to describe thepropagation of waves in ^p, while the standard equation of motionfor compressible inviscid fluids is used for ^f, with appropriateboundary conditions at the contact surface between ^f and ^p.Also, absorbing boundary conditions for the artificial boundariesof ^p are derived for the model, their effect being to make themtransparent for waves arriving normally First, results on the existence and uniqueness of the solutionof the differential problem are given and then a discrete-time,explicit finite element procedure is defined and analysed, withfinite element spaces suited for radially symmetric problemsbeing used for the spatial discretisation.     

[Fe(CO)2P(OPh)32(CS)]. The first stable thiocarbonyl derivative of iron(0) pentacarbonyl

In some circumstances, P-nBu₃ pr P-nBu₃/CC1₄ desulphurises [Fe(CO)₂{P(OPh)₃}₂(CS₂)] to give [Fe(CO)₂{P(OPh)₃}₂(CS)] which has trigonal bipyramidal coordination about the iron atom with the phosphite ligands in axial positions.     

THE PHOTOADDITION OF NUCLEOPHILES TO URACIL

Abstract— Quantum yields for 254 nm ultraviolet photoaddition of the nucleophiles hydrazine, HCN, HSO₃^-, methyl amine, and BH₄^- to uracil have been measured; the quantum yields for hydrazine, HCN, and HSO₃^- additions are pH-dependent. The nucleophiles sulfide, azide, chloride, bromide, iodide, nitrite and thiocyanate failed to photo–add under similar conditions. These reactions are interpreted as 1,4-additions to the conjugated enone system of the anti-aromatic compound, uracil; as suggested by S. Y. Wang (Wang and Nnadi, 1968). The nuclear magnetic resonance (NMR) spectrum of the photohydrate of uracil-5-d-showed that the proton was added to the 5-position in a stereochemically random manner. The photoaddition of HSO₃^- takes place at much lower concentrations than required for the thermal addition of this anion and is also stereochemically random.