Reconstruction of through-surface underwater imagery

We present a technique for rectifying distorted imagery collected by an upward-looking, submerged camera for the purpose of reconstructing the above-surface scene. Radial surface slope is deduced near extinction boundaries separating regions of transmission and internal reflection. The radial slope measurements are fit to an estimate of the distorting surface, which is recursively improved so as to minimize the quadratic measurement error. The surface is assumed to obey linear wave dynamics. After surface estimation, the above-surface scene is reconstructed by inverse ray tracing. Results of testing the wave estimation and inverse-ray tracing algorithms against simulated underwater data are presented.     

The excess energy approach to the impact testing of plastics

This paper evaluates the excess energy approach to impact testing of plastic samples. This approach assumes that providing the impact energy is excessive, the rate of strain during a test may be assumed to be constant. This allows a direct transformation of time to displacement during a test and consequently to a simplification of the integration procedure. The force-time and force-displacement responses of samples to impact have been measured simultaneously using an instrumented falling weight impact machine. It is concluded that the excess energy approach is acceptable providing the available impact energy exceeds the impact strength of the sample by a factor of ten.     

Alkyl Ether Analogs of Chlorophyll-a Derivatives: Part 1. Synthesis, Photophysical Properties and Photodynamic Efficacy

The synthesis, preliminary in vivo biological activity, singlet oxygen and fluorescence yields of a series of alkyl ether derivatives of chlorophyll-a analogs are described. For short-chain carbon ethers (1–7carbon units), it was observed that the biological activity increased by increasing the length of the carbon chain, being maximum in compounds with n-hexyl and n-heptyl chains. Related sensitizers prepared by reacting 2-(1-bromoethyl)-2-devinylpyropheophorbide-a with (sec)alcohols were found to be less effective. Under similar treatment conditions, photosensitizers containing cis- and trans- 3-hexenyl side chains were ineffective. Thus, both stereochemical and steric factors caused differences in sensitizing activity. In general, pyropheophorbide-a analogs were found to be more active than related chlorin e₆ derivatives, in which the isocyclic ring (ring “E”) was cleaved. Related photosensitizers in the 9-deoxy- series were found to be as effective as the corresponding pyropheophorbide-a analogs. The photosensitizers prepared from pyropheophorbide-a methyl ester and chlorin e₆ trimethyl ester have long wavelength absorption at 660 nm (ε 45000 to 50000). Reduction of the carbonyl group in the pyropheophorbide-a to methylene (ring E) resulted in a blue shift to 648 nm (ε 38000).     

Ionic and radical addition of chlorine,bromine and some halogen systems of butadiene monoxide (4)

Ionic reactions of bromine, chlorine, methyl hypochlorite or N-bromosuccinimide with butadiene monoxide ( 4 ) give only 1,2-addition products. The Markownikoff (1-halo-2-methoxy-3,4-epoxybutane) and anti-Markownikoff (2-halo-1-methoxy-3,4-epoxybutane) product ratios for ionic reaction of methyl hypochlorite and N-bromosuccinimide in methanol with 4 are similar to those obtained with 1-hexene. These data indicate that a rather symmetrical halonium ion is formed in the ionic halogenation of 4 . Free radical reaction of bromine, chlorine, or trichloramine to 4 does not give ring-opened products as one might expect for formation of an epoxy carbonyl intermediate. The mechanistic implications from these observations are discussed.     

Two-photon dissociation of the NO dimer in the region 7.1-8.2 eV: excited states and photodissociation pathways

A study of excited states of the NO dimer is carried out at 7.1-8.2 eV excitation energies. Photoexcitation is achieved by two-photon absorption at 300-345 nm followed by (NO)(2) dissociation and detection of electronically excited products, mostly in n=3 Rydberg states of NO. Photoelectron imaging is used as a tool to identify product electronic states by using non-state-selective ionization. Photofragment ion imaging is used to characterize product translational energy and angular distributions. Evidence for production of NO(A (2)Sigma(+)), NO(C (2)Pi), and NO(D (2)Sigma(+)) Rydberg states of NO, as well as the valence NO(B (2)Pi) state, is obtained. On the basis of product translational energy and angular distributions, it is possible to characterize the excited state(s) accessed in this region, which must possess a significant Rydberg character.     

Spectroscopic Characterisation of Metallo-Cyclodextrins for Potential Chiral Separation of Amino Acids and L/D-DOPA

The derivatives 6-Deoxy-6-[1-(2-amino)ethylamino]-β-Cyclodextrin (CDEn), 6-Deoxy-6-[1-(3-amino)propylamino]-β-Cyclodextrin (CDPn) and 6-Deoxy-6-[1-(4-amino)butylamino]-β-Cyclodextrin (CDBn) were assessed with a view to demonstrating that increasing the chain length of the diaminoalkane moiety can affect the chiral selectivity of the metallo-complexes of these materials. It was shown that IR and Raman spectroscopies can be used to characterise these compounds. The results obtained from the electronic absorption spectra suggested the formation of CuCDAm binary complexes and that the derivatives CDEn and CDPn act as bidentate ligands while CDBn acts as a monodentate ligand due to its longer alkane chain. This study also showed that in the ternary complexes with DOPA there is further coordination of the metal ion to the amino nitrogen atom and the hydroxyl oxygen atom of the drug. On the basis of the results of the circular dichroic spectroscopic studies it was suggested that CuCDEn is the better enantioselective material for DOPA and it acts in a multi-site recognition manner, utilising the inclusion properties of the CD cavity in cooperation with the coordination properties of the metal ion.     

A method for the determination of some organophosphorus insecticides in human serum

Summary A simple and rapid method for the determination of organophosphorus insecticides in serum of poisoned patients is described. The compounds are extracted with benzene and the extraction residue is gas chromatographed on a glass capillary column with alkali flame ionisation detection. Concentrations from 2 ng cm⁻³ can be determined. As an example, results of the analysis of serum samples of three patients, poisoned with parathion and methylparation, are given.     

Pulse radiolysis studies of styrene

We have applied the pulse radiolysis technique of studying short-lived, radiation-produced intermediates to a study of pure, dry liquid styrene. We have observed at least three distinct species. The most rapidly decaying species (τ1/2 = 4 μsec., λ_max ≈ 370 mμ) exhibits an apparent first-order decay which is slowed down in the presence of dry oxygen, occurs too rapidly to be measured in the presence of water, and has a temperature coefficient of approximately 1 kcal./mole between 25 and 45°C. We have tentatively identified the species as the styryl anion with a G value for formation of approximately 0.15. A second species (τ1/2 = 220 μsec. λ_max ≈ 320–330 mμ) exhibits a first-order decay which appears to be independent of oxygen and water. From its spectrum, we have tentatively identified it as the styryl radical. The third species (λ_max ≈ 310 and 320 mμ) is relatively stable in the dark, but is radily photolyzed by the analyzing light of the usual experimental set-up for pulse radiolysis studies. The formation of this species appears to be independent of the water and oxygen content of the styrene.