Loss of linker histone H1 in cellular senescence

Cellular senescence is a tumor-suppressing mechanism that is accompanied by characteristic chromatin condensation called senescence-associated heterochromatic foci (SAHFs). We found that individual SAHFs originate from individual chromosomes. SAHFs do not show alterations of posttranslational modifications of core histones that mark condensed chromatin in mitotic chromosomes, apoptotic chromatin, or transcriptionally inactive heterochromatin. Remarkably, SAHF-positive senescent cells lose linker histone H1 and exhibit increased levels of chromatin-bound high mobility group A2 (HMGA2). The expression of N-terminally enhanced green fluorescent protein (EGFP)–tagged histone H1 induces premature senescence phenotypes, including increased levels of phosphorylated p53, p21, and hypophosphorylated Rb, and a decrease in the chromatin-bound endogenous histone H1 level but not in p16 level accumulation or SAHF formation. However, the simultaneous ectopic expression of hemagglutinin-tagged HMGA2 and N-terminally EGFP-tagged histone H1 leads to significant SAHF formation (P < 0.001). It is known that histone H1 and HMG proteins compete for a common binding site, the linker DNA. These results suggest that SAHFs are a novel type of chromatin condensation involving alterations in linker DNA–binding proteins

Caracterização de fibras de esponjas de Luffa cylindrica para utilização em compósitos com matriz polimérica

Orientadora: Thais H. D. SydenstrickerCoorientador: Sandro C. AmicoDissertação (mestrado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduação em Engenharia - PIPEInclui referências: p. 127-139Área de concentração: Engenharia e Ciência dos MateriaisResumo: Neste trabalho foram estudadas fibras de esponjas de Luffa cylindrica e seus compósitos com matriz de Poliéster Insaturado Ortoftálico. Fibras de esponjas de Luffa cylindrica (mesh 40-60-100) foram tratadas com soluções aquosas de NaOH a 2% (p/p) em diferentes tempos (10 a 90 minutos) e metacrilamida em diferentes concentrações (1 a 3% p/p) e tempos entre 60 a 180 minutos. Os tratamentos químicos causaram modificações superficiais nas fibras. As fibras foram caracterizadas através de determinações analíticas (holocelulose, celulose, hemicelulose, lignina e outros componentes), análise térmica, espectrometria na região de infravermelho (FTIR), Difração de Raios X, espectrometria eletrônica para análise química e fotoelétrons (ESCA/XPS), microscopia eletrônica de varredura (MEV) e determinações de densidades. Os compósitos produzidos foram caracterizados através de análise térmica, microscopia eletrônica de varredura, de suas propriedades físico-química e mecânicas e de absorção de água. Os ensaios de resistência à tração e impacto foram analisados através do teste de ANOVA. Numa segunda etapa foram preparados compósitos com mantas de Luffa com diferentes frações volumétricas de fibras (%Vf), sendo caracterizados através de resistência à tração. Os compósitos com manta (%Vf entre 24,4 a 36,3%) tratadas com soluções de NaOH 2% (p/p) apresentaram melhores resultados para os ensaios de resistência à tração do que os compósitos com fibras curtas (%Vf 46,6).Abstract: In this work, sponge-groudo of Luffa cylindrica fibers and their composites with polyester matrix were studied. Luffa cylindrica fibers (mesh 20-60) were treated with sodium hidroxide aquosous solution (NaOH 2% w/w) during different periods of time (10-90 minutes) and with Methacrylamide aquosous solution (1-3% w/w) also during different periods (60-180 minutes). The chemical treatment caused superficial modifications on the fibers than were characterized by analytical determinations (holocellulose, cellulose, lignina, ashes and the other components), thermal analysis, eletronic spectroscopy for chemcial analysis, infrared spectroscopy, x-ray diffraction, scanning electron microscopy and density determination. Composites were characterizated by thermal analysis, scanning electron microcopy and their physico-chemical and mechanical properties else than their water absorption. Tensile and impact test were evaluated by ANOVA test. In a second stage of this work composites were prepared with Luffa cylindrica natural mats with different fiber content were characterized by tensile tests. Composites prepared with NaOH treated mats presented better tensile results than the composites prepared with short-fiber NaOH treated samples

Desenvolvimento de sorventes à base de espumas de poliuretanos flexíveis para o setor do petróleo

Orientadora: Thais H.Sydenstricker Flores-SahagunCo-orientadores: José V.C.Vargas e Sandro C.AmicoInclui apendiceTese (doutorado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduaçao em Engenharia - PIPE. Defesa: Curitiba, 21/12/2007Inclui bibliografiaÁrea de concentraçao: Engenharia e ciencias de materiai

イシバシ タンザン ケンキュウ

卒業論文(Thesis

Sponge Gourd (Luffa Cylindrica) Reinforced Polyester Composites: Preparation and Properties

Increasing environmental concern along with the drive to find substitutes for synthetic fibers and value added applications for low cost and renewable plant fibers have led to the development of composites based on biomaterials. One of the drawbacks encountered in such exercise is the lack of adhesion between the incorporated plant fibers and synthetic polymeric matrices. Such drawback can be reduced by appropriate treatment of fibers. This paper describes the chemical treatments used on sponge gourd (Luffa cylindrica) fibers of Brazil to prepare their composites with polyester resin. Production of short fiber-polymer composite as well as mat-polyester composites is presented here. Characterization of the composites in respect of evaluation of density, water absorption, thermalstability, tensile properties and impact strength were made and the results are discussed. Observed impact strengthand tensile properties are discussed based on the fractographic studies of the composites.Defence Science Journal, Vol. 64, No. 3, May 2014, pp. 273-280, DOI:http://dx.doi.org/ 10.14429/dsj.64.732

Development of highly filled phenolic resin-endocarp particles of coconut (Cocos nucifera) composites.

IUFROLAT 2013. Disponibilizado online. Resumen

Characterisation of mechanical and thermal properties in flax fabric reinforced geopolymer composites

This paper presents the mechanical and thermal properties of flax fabric reinforced fly ash based geopolymer composites. Geopolymer composites reinforced with 2.4, 3.0 and 4.1 wt% woven flax fabric in various layers were fabricated using a hand lay-up technique and tested for mechanical properties such as flexural strength, flexural modulus, compressive strength, hardness, and fracture toughness. All mechanical properties were improved by increasing the flax fibre contents, and showed superior mechanical properties over a pure geopolymer matrix. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) studies were carried out to evaluate the composition and fracture surfaces of geopolymer and geopolymer/flax composites. The thermal behaviour of composites was studied by thermogravimetric analysis (TGA) and the results showed significant degradation of flax fibres at 300 °C

Acoustic and mechanical properties of luffa fiber-reinforced biocomposites

This chapter presents an overview of acoustic and mechanical behaviors of luffa fiber reinforced biocomposites. A growing number of studies are examining the composites of biodegradable fibers such as flax, hemp, kenaf and luffa due to the adverse effects of chemical materials on nature. The low cost and superior acoustic and acceptable mechanical properties of biocomposites make them very attractive for practical applications such as sound and vibration isolation. However, the acoustic and mechanical characteristics of biocomposites and their dynamic behaviors should be fully determined before considering them for practical applications. In this chapter, acoustic properties, such as sound absorption and transmission loss, and mechanical properties, such as damping and elasticity of luffa fiber reinforced composites, are presented. The variations in acoustic and mechanical properties due to different samples and manufacturing process are explored.WOS:000532438200017Scopus - Affiliation ID: 60105072Book Citation Index- ScienceArticle; Book ChapterOcak2019YÖK - 2018-1