Behavioural sensitisation

Alderson HL, Faulconbridge LF, Gregory LP, Latimer MP, Winn P (2003) Behavioural sensitisation to repeated d-amphetamine effects of excitotoxic lesions of the pedunculopontine tegmental nucleus. Neuroscience 118 311-315... 

The glycidyl adducts are skin irritants similar in behaviour in this respeet to the parent amines. The skin sensitisation effects in the primary aliphatic amine may be reduced by addition of groups at the nitrogen atom. The hydroxyethyl group and its alkyl and aryl derivatives are the most effective found so far. 

The behaviour of austenitic stainless steels in caustic solutions has received less attention than cracking in chloride environments. Transgranular cracking has been reported for low-carbon (< 0.05%) steels in caustic solutions, whereas higher carbon content alloys cracked intergranularly. Wilson and Aspen showed that resistance to cracking was not decreased by sensitisation heat treatments. Type 316 stainless steel has been shown to be more susceptible to cracking in caustic than type 304. ... 

The electrochemical examination of fusion joints between nine pairs of dissimilar metal couples in seawater showed that in most cases the HAZ was anodic to the weld metals" . Prasad Rao and Prasanna Kumarundertook electrochemical studies of austenitic stainless steel claddings to find that heat input and 5Fe content significantly affected the anodic polarisation behaviour under active corrosion conditions whilst Herbsleb and Stoffelo found that two-phased weld claddings of the 24Cr-13Ni type were susceptible to inter-granular attack (IGA) as a result of sensitisation after heat treatment at 600°C /pa was unaffected by heat input. 

Tolerance, sensitisation, craving, withdrawal and relapse may actually be more complicated than indicated above and may involve separate mechanisms which are too complex to summarise here (See Altman et al., 1996). Recent research on specific drugs of abuse is reviewed by several authors in a special issue of Trends in Pharmacological Sciences 13 169-219 (1992). However, the concept of addiction as "an emotional fixation. .. acquired through learning, which intermittently or continually expresses itself in a purposeful stereotyped behaviour with the character and force of a natural drive, aiming at a specific pleasure or the avoidance of specific discomfort (Bejerot, 1980) still broadly applies. 

Interest continues in the photochromic behaviour of the spiropyran and related systems both in the patent and the basic research literature. Nanosecond laser kinetic spectroscopy has been used to investigate the intermediates involved in the interconversions between the colourless spiropyrans (35) and (36) and the coloured merocyanines present in solution at room temperature as the -isomers (37) and (38). On excitation (530 nm) of nitro derivative (37) in acetone, two transients were observed, the triplet excited state (lifetime 6ps) and the Z-isomer (lifetime 0.3ms). The same transients were observed on excitation (353 nm) of the spiropyran form (35). Naphthalene or benzophenone sensitisation of the photo-... 

Armesto and co-workers have reported the photochemical behaviour of the vinylcyclopropane derivatives (98) under w-methoxyacetophenone sensitisation in methylene chloride as the solvent. A variety of products are formed, the nature of which is dependent upon the substituent on the cyclopropyl ring. The key intermediate is believed to be the biradical (99) that is formed following energy transfer. A study of the effect of wavelength on the outcome of the irradiation of (100) has been reported. At short wavelengths (250 and 254 nm), it is thought that the S2 state of (100) is populated and this results in the formation of the three products (101), (102) and (103) in a ratio of 6 1 1. 

The stereochemistry of other photocycloadditions can be examined by considering, for instance, the reaction of cis and trans 1,2-dichloroethylene with indene , and the addition of dimethyl maleate and fumarate to acetone. In the former process (sensitised by benzophenone) two products syn and anti) are possible for each stereochemical relation of the two chlorine atoms. Taking together the two cis and the two trans products, the behaviour of the systems can be described as follows " ... 

Recently also, silica materials doped with sensitiser-modified NIR luminescent lanthanide complexes have been described [73] as well as NIR luminescent meso-porous materials [74] doped with such complexes. These reports do not describe the behaviour of these materials as nanoparticles in suspension, but the synthesis procedure might be adapted to obtain such materials suitable for use in biological media. The encapsulated lanthanide complexes appear to have luminescent characteristics very similar to the complexes in solution (e.g. luminescence decay times), although the silica-based ytterbium(III) and neodymium(lll) materials show a roughly twofold increase in NIR luminescence intensity when they are dried for 3 weeks at 50°C. No indications exist that the encapsulation in these materials drastically improves the photoluminescence quantum yield of NIR luminescent lanthanide complexes. 

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