Reproduction de : Thèse doctorat : Littérature comparée : Cergy-Pontoise : 2006. / Titre provenant de l'écran titre. Bibliogr. p.550-590. Index.

Understanding the motives for sunbathing and indoor tanning is an extremely important public health issue. Skin cancer rates have increased dramatically in recent years and UV exposure via sunbathing and utilization of sun lamps and tanning beds are considered important risk factors. Motives for sunbathing and tanning salon use have been thought to be related to appearance concerns, yet little research has examined the specific tan appearance attitudes that may contribute to use of these behaviors. Two studies were conducted with the aim of assessing distinct attitudes related to a tan appearance. In the first study items were created based on a review of the tanning literature and incorporation of constructs developed in the body image field, which were subsequently subject to exploratory factor analysis on 149 female university student sunbathers/tanning salon users.

Waste management in the leather industry worldwide is an issue of major importance for both solid and liquid wastes. It has been recognised that there are major environmental impacts from the poorly managed disposal of such wastes and these have a clear health impact upon human society. Within Europe, under EU driven legislation, the costs of wastes management are increasing rapidly and there is a clear need to research improved methods to cost effectively deal with leather industry wastes. Biodegradation (anaerobic), as a management option, of solid wastes from the leather industry is an area that is attracting increased interest in recent years as being a technique that has wide public acceptability as well as process efficiency. However, tanning agents that prolong the lifetime of leather goods have a negative impact on biodegradation and this needs to be addressed before efficient treatment can occur. To drive the agenda this research has the aims of • Highlighting the effects of tanning agent on anaerobic digestion. • Understanding the mechanism(s) by which different leather tannages can biodegraded. • Developing a process to reverse the action of tannage. Leather solid wastes were anaerobically digested using Serum Bottle Assays (SBA). The effect of a range of vegetable, mineral and aldehyde tanning agents of leather on the rate of anaerobic digestion was assessed. Common tanning agents used included; myrica, valonea, glutaraldehyde and chrome. To further identify key factors for cost effective anaerobic digestion, tanned hide powders and tanned leathers were also pre-treated using autoclaving, liming, enzymes etc, in an attempt to determine whether tannage may be reversed. Major techniques used in the research include: anaerobic digestion, Biochemical Methane Potential (BMP), Total Solids contents (TS), Gas Chromatography (GC) and Gas Chromatography Mass Spectrometry (GC-MS). Hydrolysable tannins are less resistant to anaerobic digestion than condensed tannins. However, enzymatic pre-treatment reduces the resistance and this offers a new effective pre-treatment route. Thermal pre-treatment also decreased resistance to anaerobic digression especially for chrome, glutaraldehyde, myrica and tannic acid tanned leathers. Chemical pre-treatment also generally lowered the resistance to anaerobic digestion. Selective pre-treatment offers a means of improving the cost effectiveness of anaerobic digestion of leather and therefore enabling a new waste management method to be adopted by the industry. A relationship emerges, in some cases, between chemical structure of tanning agent and inhibition of anaerobic digestion. This offers the possibility of producing new, designed organic tanning agents with, suitable properties, to be adopted by the industiy, The research agenda within the leather industry is still ongoing and recommendations for future research are addressed

The most significant problem of the tanning industry is waste generation. The presence of chromium in leather waste represents a potential hazard due to the possibility of Cr(III) being converted to its toxic state, Cr(VI). The treatment of chrome-tanned leather waste described in this research occurs in three phases: dechroming; isolation of gelatin, and application of the gelatin produced in the finishing of leather. Chrome-tanned shavings were dechromed and subsequently used for the production of gelatin. Gelatin was isolated from dechromed shavings in a one-step process, through thermal and chemical hydrolysis, using the hydrolytic agents ammonia, sodium hydroxide and acetic acid. The gelatin obtained through thermal hydrolysis exhibited better properties, in terms of gel strength, melting point, swelling and thermal properties, than the gelatin obtained through chemical hydrolysis and the former process was more cost-effective in terms of time, chemicals and waste production. The use of gelatin may be limited by its poor mechanical properties. The introduction of chemical modifications, using the crosslinking agents glutaraldehyde (GTA), oxazolidine II, ethylene glycol cliglycidyl ether (epoxy compound), hexamethylene dii socyanate (HMDC) and I -ethyl-3 -(3 -dimethylaminopropyl) carbodiimide (EDC), improved the performance in terms of strength and stability of the gelatin: oxazolidine and ethylene glycol diglycidyl ether are the most suitable since they confer plasticising properties in addition to stabilising the gelatin. A plasticiser (glycerol) was added into the matrix network of gelatin, increasing its flexibility. The isolated gelatin and a mixture of gelatinlglycerol were compared in use as a replacement for the commercial protein binder, casein, for glazed finishing. The finishing formulations were crosslinked with epoxy compound and oxazolidine. Physical tests carried out on the finished product showed promising results, with the gelatin/epoxy formulation showing potential for application. Ihe potential fbr gelatin isolated from chrome shavings to he produced as a high-added value material lor new applications in the future, such as a component tor finishing Formulations in the leather industry, was demonstrated

Das Strukturprotein Kollagen ist der Hautbestandteil von Haut und somit geeignet, die Gerbung auf molekularer Ebene zu studieren. Das schon sehr alte Handwerk des Gerbens hat das Ziel die Kollagenmatrix so zu stabilisieren, dass diese stabil und flexibel bleibt, auch wenn die Feuchtigkeit entweicht und das Leder hohen Temperaturen ausgesetzt ist. Als Größe zur Charakterisierung der Gerbung dient die Schrumpfungstemperatur. Erkenntnisgewinn auf molekularer Ebene ist Ziel der Untersuchungen, da die Mechanismen der Gerbung bis heute nicht vollständig verstanden sind und grundlegend für die Synthese neuer Gerbstoffe sind. Die Kinetik der Assemblierung von Kollagenmonomeren zu Fibrillen wird spektroskopisch studiert. Der Einfluss von Additiven kann somit auf molekularer Ebene evaluiert werden. Ergänzend wird die Morphologie der Assemblate betrachtet. Studien der anschließenden Deassemblierung liefern Informationen über die Festigkeit der Kollagenmatrix. Für die Korrelation der Modellreaktion mit dem Realsystem der Gerbung werden Schrumpfungstemperaturen gemessen und Strukturuntersuchungen durchgeführt. Für diese Untersuchungen wird Hautpulver eingesetzt, um homogene Ergebnisse zu garantieren. Drei praxisrelevante Stoffgruppen, nämlich Chrom, Aldehyde und Polyphenole, wurden untersucht. Der Hauptgerbstoff Chrom zeigt bei den Assemblierungsuntersuchungen nur geringe Auswirkungen auf das Modellsystem. Die Deassemblierung hingegen lässt die gute Gerbeigenschaft klar erkennen. Zur Erklärung des Streifenmusters, das bei chromgegerbten und somit positiv gestainten Fibrillen im TEM zu erkennen ist, wurde ein theoretischer Ansatz unternommen. Glutaraldehyd und Formaldehyd werden zur Gerbung benutzt. Aldehyde vernetzen die Kollagenmatrix kovalent. Die Untersuchung der homologen Reihe der Dialdehyde wurde hinsichtlich einer Tendenz oder einem Optimum in der Moleküllänge untersucht. Die Aldehyde vernetzen die Monomere, sodass in den Assemblierungskinetiken nur verminderte Plateauhöhen erreicht werden. Die Minimierung der Plateauhöhe kann nicht quantitativ mit der Gerbwirkung gleichgesetzt werden. Mit Aldehydzusatz assemblierte Fibrillen haben ein unverändertes Erscheinungsbild. Die Schlussfolgerung ist, dass die Fibrillenstruktur nicht verändert, aber dezimiert ist. Da nur Formaldehyd, Glyoxal und Glutaraldehyd als reine wässrige Lösung vorlagen mussten die andern drei Dialdehyde hergestellt werden. Dabei sind zusätzliche Substanzen in den Lösungen enthalten, die die Ergebnisse stören. Einen Trend, der mit der Moleküllänge einhergeht, konnte nicht beobachtet werden. Dies ist mit der flexiblen Ordnung der Moleküle in Lösung - im Gegensatz zur Kollagenmatrix in der Haut - zu begründen. Eine kombinierte Wirkung von Chrom und Aldehyd konnte bei der Assemblierung nachvollzogen werden und belegt die Annahmen zur Gerbung aus der Literatur, dass die Gerbung über die sauren Seitenketten bzw. über die Aminogruppen geschieht. Die untersuchten Polyphenole haben keine gerbende Wirkung, sind dem Naturgerbstoff Tannin chemisch aber sehr ähnlich, sodass der Unterschied in der räumlichen Struktur liegen muss. Die Kondensate werden bezüglich ihrer Kettenlänge und der Anzahl ihrer funktionellen Gruppen analysiert. Die Störung der Assemblierung ist bei Zusatz von Phenolkondensaten ist stärker als bei den anderen Testsubstanzen, was eine starke Interaktion zeigt. Messungen der Schrumpfungstemperaturen an Hautpulver ergaben, dass die Syntane keinen waschstabilen Effekt haben. Die Anlagerung an das Kollagen ist folglich zu schwach. Parallele TEM-Analysen ergaben, dass der pH-Wert bei der Vernetzung einen Einfluss auf die Intensität der Streifung hat. Mit zunehmendem pH-Wert erscheint die Streifung intensiver, bis hin zu einer erkennbaren Substreifung. Bei verschieden hohen Schrumpfungstemperaturen zeichnen sind zwei Aussagen ab. Zum einen ist mikroskopisch klar zu erkennen, wenn die Probe denaturiert ist, also über ihrer Schrumpfungstemperatur gekommen ist. Zum anderen ist ein leicht verminderter D-Abstand mit zunehmenden Schrumpfungstemperaturen zu verzeichnen. Besitzen Additive eine gerbende Wirkung, so zeigt sich dies nicht analog im Assemblierungsmodell oder in der Morphologie der Fibrillen. Eindeutige Rückschlüsse sind nicht zu ziehen. Bei der Deassemblierung äußert sich die Gerbwirkung aber immer durch eine verminderte Löslichkeit der Matrix. Daher ist dies eine wertvolle Technik für die Grundlagenforschung in der Gerbung.

Tyrimo tikslas. Įvertinti merginų informuotumą apie ultravioletinės spinduliuotės poveikį sveikatai bei sąsajas su deginimosi elgsena Tyrimo metodika. Tyrimas atliktas 2013 - 2014 m. Tyrime dalyvavo Kauno kolegijos Medicinos fakulteto I ir II kurso studentės. Iš viso buvo išdalinta 580 anketų. Duomenys analizuoti naudojant SPSS 20.0 programa, lyginant studenčių deginimosi saulėje įpročius, soliariumų naudojimo ir požiūrio bei žinių apie ultravioletinius spindulius kintamuosius pagal χ2 kriterijų. Skirtumas statistiškai reikšmingas, kai pasikliovimo lygmuo p<0,05. Tyrimo metodas – anoniminė anketinė apklausa. Rezultatai: 68,1 proc. studenčių nuomone saulės spinduliai gali sukelti akių pažeidimus - kataraktą. Merginos turinčios jautresnę I-II odos tipą teigia, kad saulės spinduliai sukelia ne tik odos, tačiau ir akių pažeidimus 75,8 proc. Didžioji dalis merginų 67,8 proc.teigė, kad oda raukšlėjasi saulės poveikyje. Statistiškai reikšmingai dažniau I-II odos tipo merginų 89,6 proc. teigė, kad daugėja raukšlių odoje deginantis soliariume negu mažiau jautrią odą turintis III-IV odos tipas. Apie odos senėjimą saulės poveikyje I-II ir III-IV odos tipų merginos teigė, kad saulė mažina odos elastingumą ir spartina senėjimą 87,9 ir 87,1 proc. pigmentinės dėmės suvokiamos kaip neigiamas veiksnys ir 68,1 proc. merginų teigė, kad būtent saulės poveikyje atsiranda įvairūs pakitimai odoje. Statistiškai reikšmingai dažniau III-IV odos tipų merginų 7,1 proc.teigė, kad soliariumo spinduliai... [toliau žr. visą tekstą] / The purpose of the investigation. To assess the effects of exposure of ultraviolet radiation, to the young women's awareness of health and interfaces with tanning behaviors. Methodology of the Study. Study was carried out in 2013-2014 in the study participated I and II course women of Kaunas College of Medicine faculty. A total of 580 questionnaires were handed out. Data analysed using SPSS program 20.0, comparing female students tanning in the Sun habits, attitudes and the use of ultraviolet rays, according to the knowledge of the variables of x2 criteria. The difference statistically significant when the confidence level p < 0,05. A questionnaire - based survey method to anonymous access. Results: 68,1 percent of the female students think, that sun's rays can lead to cataracts-ocular lesions. Girls having more sensitive skin type I-II argues that the sun's rays causes not only the skin, but also violations of eyes 75,8 percent. The most part of girls 67,8 percent claimed that skin wrinkling sun effecting. Statistically significant more often I-II type of skin girls 89,6 percent said that a growing number of wrinkles in the skin scorching solarium than less sensitive skin with skin type III-IV. About the ageing of the skin of the Sun effecting I-II and III- IV skin types girls claimed that the Sun reduces the elasticity of the skin and accelerates the ageing 87,9 and 87,1 percent pigmented spots seen as a negative factor and 68,1 percent of girls said, that a variety of... [to full text]

The melanocortin-1 receptor (MC1R) is a G-protein coupled receptor (GPCR) expressed on the surface of the melanocyte. MC1R activation after UV exposure results in the production of the dark eumelanin pigment and the tanning process in humans, providing protection from UV induced DNA damage. MC1R activation has also recently been linked to DNA repair. The MC1R gene is highly polymorphic in Caucasian populations with a number of MC1R variant alleles associated with red hair, fair skin, poor tanning and increased risk of melanoma and non-melanoma skin cancer. These MC1R variant receptors were thought to be loss of function, however the type of defect and the extent of the loss of function for individual variants was relatively unknown before the commencement of this PhD project. Many GPCR mutant proteins are intracellularly retained, resulting in a loss of signalling ability. To determine if this was the case for MC1R variant receptors, the localisation of the wild type and variant MC1R protein was investigated using immunofluorescence and radio-ligand binding on transfected melanocytic cells as well as primary melanocyte strains. For the first time, several MC1R variants including V60L, R151C, I155T, R160W and R163Q, were shown to have reduced cell surface expression compared to wild type MC1R. cAMP assays were used to determine the signalling ability of activated wild type and variant MC1R, importantly, variant receptors with reduced cell surface expression showed corresponding impairment in cAMP signalling. In contrast, the R142H and D294H variants, which have normal cell surface expression but significantly impaired cAMP signalling, are thought to have a defect in G-protein coupling. Some MC1R variants were found to have dominant negative activity on the wild type receptor in co-expression studies, this result may explain the MC1R heterozygote effect on human pigmentation phenotypes. This dominant negative effect resulted in either reduced wild type cell surface expression or reduced G-protein coupling and may be mediated by receptor dimerisation. In order to validate the in vitro studies, comparison of variant receptor characteristics with skin and hair colour data of individuals both homozygous and heterozygous for MC1R variant alleles was performed. This revealed parallels between variant MC1R cell surface expression, functional ability, dominant negative activity and the strength of the effects of variant alleles on human pigmentation. From the in vitro functional studies, it was clear that most variant receptors retained some signaling ability, although the relative abilities varied. An important unanswered question in the literature was whether the phenotype of carriers of the high penetrance MC1R variant alleles was actually representative of complete loss of function for MC1R. Due to the rarity of MC1R null alleles they had only previously been found in the heterozygous state, however we described the phenotype of one individual compound heterozygous for two frameshift mutations resulting in an individual unable to produce any functional MC1R protein. Phenotypic analysis indicated that red hair and fair skin is found in the absence of MC1R. Finally, preliminary studies using low temperature, chemical or pharmacological chaperones indicated that the cell surface expression of some MC1R variants could be rescued in cell transfection experiments. This resulted in a restoration of signaling ability after stimulation with agonist. These studies into the localization and function of MC1R variants have contributed to a greater understanding of the molecular mechanism underlying the association of MC1R with skin cancer risk phenotypes, and may lead to future drug based therapies that are able to rescue the function of MC1R variants that are intracellularly retained.

An enzyme treatment process for the pre-tanning of sheepskins has been previously reported by the Leather and Shoe Research Association of New Zealand (LASRA) as an alternative to current industry operations. The newly developed process had marked benefits over conventional processing in terms of a lowered energy usage (73%), processing time (47%) as well as water use (49%), but had been developed as a “proof of principle’’. The objective of this work was to develop the process further to a stage ready for adoption by industry. A process ready for adoption by industry is one that is able to generate good quality products (good quality products are those that has solids removed to industry standards, without visible damages to grain surface, evenly dyed etc.), require minimal changes to plant or operation layout and reduce usage of resources (e.g. water and chemicals). Mass balancing was used to investigate potential modifications for the process based on the understanding developed from a detailed analysis of preliminary design trials. Results showed that a configuration utilising a 2 stage counter-current system for the washing stages and segregation and recycling of enzyme float prior to dilution in the neutralization stage was a significant improvement. Benefits over conventional processing include a reduction of residual TDS by 50% at the washing stages and 70% savings on water use overall. Benefits over the un-optimized LASRA process are reduction of solids in product after enzyme treatment and neutralization stages by 30%, additional water savings of 21%, as well as 10% savings of enzyme usage. The optimized (new) LASRA process uses existing equipment and requires no additional outlay of capital. The process is now developed to a point where it should be trialled at industrial scale.

Artigos de couro estão associados com tendências de moda e sofisticação em produtos de consumo. No processamento do couro, a fase de acabamento consiste de um conjunto de operações e tratamentos, essencialmente de superfície, que conferem características finais ao produto. Os objetivos do acabamento são reduzir defeitos visíveis, modificar as propriedades superficiais e melhorar os atributos de uso. Nesta fase final, são aplicadas, dentre outros produtos, resinas, geralmente, poliacrilatos e poliuretanos, e algumas vezes caseínas e outros polímeros que formam filmes de recobrimento protetores sobre o couro. Nesse contexto, este trabalho visa a uma avaliação dos filmes formados com resinas comerciais utilizadas industrialmente no acabamento de couros, relacionando a composição destes materiais com características sensoriais, com resistência mecânica, através de testes de tração, com estabilidade à água ou a solvente orgânico, com análise de dureza, e através de caracterizações por infravermelho e DSC. Ensaios de tração mostraram que as resinas poliuretânicas, no geral, apresentam uma maior resistência à tração quando comparadas com resinas acrílicas, assim como os valores de tenacidade, indicando que esses filmes suportam um maior impacto para levar o material à ruptura. A adição de pigmentos diminui essa resistência, tanto em resinas acrílicas quanto em resinas poliuretânicas, enquanto que a produção de filmes compactos apresenta características intermediárias com relação aos componentes puros. Todos os filmes acrílicos testados apresentaram uma maior capacidade de alongamento. Com relação à dureza, as resinas que se mostraram mais flexíveis e com maior alongamento, foram as que apresentaram menor dureza. A estabilidade dos filmes com relação à água e solventes mostrou que os componentes solúveis em água e em solvente aumentam com a presença de pigmento e que a absorção de água é maior e de solvente é menor em filmes com pigmento, tanto para acrilatos quanto para poliuretanos. As caracterizações a partir de análise por FTIR e DSC indicaram os grupamentos químicos e picos de temperaturas característicos dos acrilatos e poliuretanos, respectivamente. / Leather goods are associated with fashion trends and sophistication in consumer products. In the leather processing, the finishing phase consists of a series of operations and treatments, essentially in surface, conferring its final characteristics. The objectives are to reduce visible defects, modify surface properties and improve the usage attributes In this final stage are applied, among other products, resins, generally polyacrylates and polyurethanes, sometimes casein and other polymers, which form protective coating films on leather. In this context, this paper evaluates the films formed with commercial polymeric resins used industrially in finishing leather, relating the composition of these materials with their sensory characteristics, with their strength by tensile testing, with its stability to water or organic solvent, with analysis of hardness and characterizations by IR and DSC. Tensile tests showed that the polyurethane resins in general have a higher tensile strength when compared with acrylic resins, as well as the toughness values, indicating that these films support a greater impact to bring the material to rupture. The addition of pigments decreases this resistance, for acrylic resins and polyurethane resins, while the production of compact film has intermediate characteristics with respect to the pure components. All acrylic films tested had a higher elongation. With respect to hardness, the resins that were more flexible and more stretching, showed the lowest hardness. The stability of the films with respect to water and solvents has shown that water soluble solvent components increased by the presence of pigment and the water absorption is higher and the solvent is lower in pigmented films to acrylates and polyurethanes. The characterizations from IR and DSC analysis indicated the chemical groups and characteristic temperatures peaks of acrylates and polyurethanes, respectively.

A indústria coureiro-calçadista, durante o processamento de peles, produz resíduos que, por causa do método de curtimento empregado, têm cromo na sua composição química. O objetivo geral deste trabalho é mostrar que é possível a reutilização do metal contido nas cinzas oriundas da incineração de aparas de couro como matéria prima na produção da liga ferro-cromo, livrando o meio ambiente de um resíduo perigoso. Trata-se de um estudo para a elaboração de uma liga com as características similares às de uma ferro-liga ferro-cromo alto carbono (FeCrAC) comercial. Uma análise termodinâmica foi realizada simulando o processo de redução do óxido de cromo com o objetivo de fundamentar e de fornecer as condições para a condução de experimentos. Ao nível de laboratório, em estágio preliminar, foi demonstrado que é possível a reutilização do cromo contido nas cinzas da incineração de aparas de couro na produção de uma liga ferro-cromo. Neste caso obteve-se uma liga com 28 % de cromo e 7% de carbono com uma recuperação metalúrgica de cromo de 69%. / The leather and shoe industry, during the process of leather tanning, produces residues that, because of the method used, have chromium in its chemical composition. The general objective of this work is to show that the recycling of the contained metal is possible as raw material for the iron-chromium alloy production, exempting the environment of a dangerous residue. This study is aimed at the production of an alloy with the similar characteristics to those of the commercial ferroalloy HCFeCr. A thermodynamic analysis was carried through, simulating the process of reduction of chromium oxide, to base and give the conditions for the experiments. At the laboratory level, in preliminary stage, it was demonstrated that the reutilization of chromium contained in ashes of the incineration of leather shavings for the production of one commercial ferroalloy HCFeCr is possible. In this case, an alloy with 28% of chrome and 7% of carbon was obtained, with a metallurgical chrome yield of 69%.