Dichroism measurements in forensic fibre examination. Part 3 - dyed cotton and viscose fibres.
A number of dyed cellulosic fibres were examined with plane polarized light on their dichroic behavior by microscopy and microspectrophotometry (MSP-PPL). Significant dichroic effects (mostly hypochromic effects and hypsochromic bands shifts) were reported. The effect is related to the chemical structure: some dye structures always possess dichroism (azo, stilbene, thiazole and oxazine), some dyes demonstrate sometimes dichroic effects (anthraquinoid, indigoid) while other structures never demonstrate dichroic effects (sulphur, diphenylmethanes, triarylmethanes, phthalocyanines). In some cases a different dichroic behavior was found for the same dyes applied on cotton and on viscose.
Dichroism measurements in forensic fibre examination. Part 2 - dyed polyamide, wool and silk fibres.
Abstract A number of dyed polyamide, wool and silk samples were examined with plane polarized light on their dichroic behavior by optical light microscopy (OLM) and microspectrophotometry with plane polarized light (MSP-PPL). It was found that most of these acid dyed peptidic fibres possess dichroism, but these are weaker than the effects previously described for polyester fibres. The small effects may be not observed, especially for wool, but these can be measured using MSP-PPL. In the three peptidic fibre classes, for the first time, a so called “inverse dichroism” is observed which appears in the absorption spectra as a hyperchromic effect.
Achievements and contradictions of the Peruvian agrarian reform
Different paths of transition to capitalist agriculture, as well as different types of agrarian reform, can be distinguished. The Peruvian agrarian reform is analysed within this context and evaluated in terms of its contribution to rural development. The Peruvian case underlines the importance of understanding the rationality of the pre‐existent agrarian system for a successful restructuring of the agrarian economy and society. The contradictions which arose between the State's model and the peasants’ model of agrarian reform, as well as those between different types of peasants, are discussed. Peru's experience is also a reminder that a land reform is not a sufficient condition for rural development unless accompanied by proper price, marketing, credit and investment policies.