Hydrogels are three-dimensional, hydrophilic, polymer networks that are able to imbibe large amounts of water or biological fluids, while maintaining their dimensional stability. The polymer binding might be achieved by chemical or physical interactions. Physical crosslinking of a polymer to form its hydrogel, might be accomplished either by casting-solvent evaporation (SC) method or by freeze-thaw (FT) technique. The physical hydrogels, especially the ones based on natural biopolymers, like polysaccharides, are being widely used in industry and medicine due to their favourable properties: biocompatibility; biodegradability; low toxicity and eco-friendly characteristics. Polysaccharides, like chitosan (CH) and (hydroxypropyl)methyl cellulose (HPMC) have gained great attention due to its stimuli sensitive properties: pH and temperature responsiveness, respectively. Thus, within this work we have developed physically crosslinked CH:HPMC hydrogel films, using both SC and FT techniques. The attained CH:HPMC membranes were evaluated in terms of their swelling, thermal (low critical solution temperature-LCST), structural (attenuated total reflectance Fourier transform infrared spectroscopy) and morphological (scanning electron microscopy and atomic force microscopy) properties. According to these results, the developed membranes exhibit a good miscibility between the two component biopolymers. Moreover, the CH:HPMC membranes exhibit a high swelling capacity (SW FT = 1,172 and SW SC = 7,323), a low surface roughness (Sq = 5.6-9.5 nm) and an elevated LCST (LCST = 85.2-87.5°C). The stimuli sensitive behaviour makes hydrogels appealing for the design of smart devices applicable in a variety of technological fields. In our particular case, we envisage the application of such materials as active substances (moisturisers, antiperspirants and scents) delivers, into textile substrates in a controlled manner.
The BolA-like protein family is widespread among prokaryotes and eukaryotes. BolA was originally described in E. coli as a gene induced in the stationary phase and in stress conditions. The BolA overexpression makes cells spherical. It was characterized as a transcription factor modulating cellular processes such as cell permeability, biofilm production, motility, and flagella assembly. BolA is important in the switch between motile and sedentary lifestyles having connections with the signaling molecule c-di-GMP. BolA was considered a virulence factor in pathogens such as Salmonella Typhimurium and Klebsiella pneumoniae and it promotes bacterial survival when facing stresses due to host defenses. In E. coli, the BolA homologue IbaG is associated with resistance to acidic stress, and in Vibrio cholerae, IbaG is important for animal cell colonization. Recently, it was demonstrated that BolA is phosphorylated and this modification is important for the stability/turnover of BolA and its activity as a transcription factor. The results indicate that there is a physical interaction between BolA-like proteins and the CGFS-type Grx proteins during the biogenesis of Fe-S clusters, iron trafficking and storage. We also review recent progress regarding the cellular and molecular mechanisms by which BolA/Grx protein complexes are involved in the regulation of iron homeostasis in eukaryotes and prokaryotes.
Raynal and the defence of the Portuguese colonization of Brazil: diplomacy and the Memoirs of the Visconde de Balsemão. This article addresses and discusses the Memoirs of Luís Pinto de Sousa Coutinho (1735-1804), 1st Viscount of Balsemão, which were used as sources for the production of the 1780 edition of the Histoire des deux Indes, in respect of Brazil. The Memoirs offer a singular and exceptional portrait of the Portuguese empire-in the most precise and well-informed manner known for the time-, and represent a substantive addition to Abbé Raynal's text and, in particular, a reorientation of its rather uncritical and even apologetic view of the Portuguese colonial administration and of slavery in Brazil.
Thearticle explores the nexus between the financialisation of non-financial firms and the growing tendencytoexternalisationof production activities,aiming to relocatethe debate on labour platformisation within the study of the evolution of firms. Taking the firm as the main mediator between finance and labour, the argument unfolds on the impact of financialization of non-financial companies onmanagement models, organisational restructuring, and the emergence of the de-jobbed organisation. Production networks, value chain and platforms are, accordingly, understood as organisational solutions based on the blurring of employment relationship as the main institutional boundary of firms.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.