Search results for " plastic"
showing 10 items of 3463 documents
Malattia di Dupuytren
2012
La malattia di Dupuytren ancora oggi rimane avvolta nel mistero: è incerta la paternità della sua prima descrizione, sebbene, e con molte polemiche, da centoottantuno anni è storicamente legata all’illustre chirurgo francese Guillaume Dupuytren. Un enigma per gli studiosi è anche la sua eziopatogenesi, in cui fattori ambientali, comportamentali, genetici, e biomolecolari, in parte ancora sconosciuti, interagiscono a più livelli, generando reazioni biochimiche a cascata che portano alla ben nota iperproliferazione dei fibroblasti e alla conseguente deposizione di collagene. Essa rappresenta inoltre una sfida per il chirurgo che deve districarsi tra tecniche operatorie differenti in relazione…
Sustainable recycling technologies for thermoplastic polymers and their composites: A review of the state of the art
2022
This review article discusses the environmental and economic effects of recycling, as well as sustainable thermoplastic polymer recycling technologies. Several researchers have utilized recycled thermoplastics as matrices in the production of a variety of natural and synthetic-based composites, which is also the focus of this study. All of the industries (food and packaging, construction and building, transportation, and indoor usage) where recycled thermoplastics have a large market share (food and packaging, construction and building, transportation, and indoor usage) are covered in this review. The desirable properties of thermoplastic polymers, such as corrosion resistance, low density,…
Macro-micro relationship in nanostructured functional composites
2012
This paper examines the results of the characterization of two functional composites: Poly(methyl methacrylate) (PMMA)-Ce:YAG (yttrium aluminium garnet doped with cerium) and PMMA-cobalt hexacyanoferrate (CoHCF). The composites were prepared as possible emitters in the fields of lighting thermal sensors. The prepared composites were char- acterized using transmission electron microscopy (TEM), nuclear magnetic resonance (NMR) spectroscopy, thermogravi- metric analysis (TGA), differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) analyses to study the correlation between micro and macro characteristics. We found that the molecular interactions of the two different fill…
Northward range expansion requires synchronization of both overwintering behaviour and physiology with photoperiod in the invasive Colorado potato be…
2014
Abstract. Photoperiodic phenological adaptations are prevalent in many organisms living in seasonal environments. As both photoperiod and growth season length change with latitude, species undergoing latitudinal range expansion often need to synchronize their life cycle with a changing photoperiod and growth season length. Since adaptive synchronization often involves a large number of time-consuming genetic changes, behavioural plasticity might be a faster way to adjust to novel conditions. We compared behavioural and physiological traits in overwintering (diapause) preparation in three latitudinally different European Colorado potato beetle (Leptinotarsa decemlineata) populations reared u…
Behavior of Calcium Phosphate–Chitosan–Collagen Composite Coating on AISI 304 for Orthopedic Applications
2022
Calcium phosphate/chitosan/collagen composite coating on AISI 304 stainless steel was investigated. Coatings were realized by galvanic coupling that occurs without an external power supply because it begins with the coupling between two metals with different standard electrochemical potentials. The process consists of the co-deposition of the three components with the calcium phosphate crystals incorporated into the polymeric composite of chitosan and collagen. Physical-chemical characterizations of the samples were executed to evaluate morphology and chemical composition. Morphological analyses have shown that the surface of the stainless steel is covered by the deposit, which has a very r…
Computable majorants of the limit load in Hencky’s plasticity problems
2018
Abstract We propose a new method for analyzing the limit (safe) load of elastoplastic media governed by the Hencky plasticity law and deduce fully computable bounds of this load. The main idea of the method is based on a combination of kinematic approach and new estimates of the distance to the set of divergence free fields. We show that two sided bounds of the limit load are sharp and the computational efficiency of the method is confirmed by numerical experiments.
Increased conformational rigidity of humic substances by oxidative biomimetic catalysis
2005
A synthetic water-soluble meso-tetra(2,6-dichloro-3-sulfonatophenyl)porphyrinate of iron(III) chloride, Fe(TDCPPS)Cl, was employed as a biomimetic catalyst in the oxidative coupling of terrestrial humic materials. High-performance size-exclusion chromatography (HPSEC), solid-state nuclear magnetic resonance (CPMAS-(13)C NMR), electron paramagnetic resonance (EPR), and diffuse reflectance infrared spectroscopy (DRIFT) were used to follow conformational and structural changes brought about in different humic materials by the oxidative coupling. Increase in apparent weight-average molecular weight (Mw(a)) occurred invariably for all humic substances with the oxidative polymerization catalyzed …
Copolymerization of Ethylene with Selected Vinyl Monomers Catalyzed by Group 4 Metal and Vanadium Complexes with Multidentate Ligands: A Short Review
2021
This paper gives a short overview of homogeneous post-metallocene catalysts based on group 4 metal and vanadium complexes bearing multidentate ligands. It summarizes the catalytic behavior of those catalysts in copolymerization of ethylene with 1-olefins, with styrenic monomers and with α,ω-alkenols. The review is focused on finding correlations between the structure of a complex, its catalyst activity and comonomer incorporation ability, as well as the microstructure of the copolymer chains.
Unveiling adaptive mechanisms though experimental evolution: the role of duplicated genes and phenotypic plasticity in yeast, and the genetic variabi…
2021
Los seres vivos se enfrentan a condiciones ambientales cambiantes y habitualmente estresantes, agravadas por el cambio climático, que ponen a prueba su capacidad de supervivencia. El cambio en la composición genética de las poblaciones reside en las mutaciones, que son la fuente para la evolución y la adaptación a los cambios. La diversidad genética intrapoblacional está regulada por dos grandes fuerzas evolutivas que cambian la composición genética permitiendo así el acceso a nuevos fenotipos: la deriva genética y la selección natural. Por un lado, la deriva genética fija mutaciones en la población de manera aleatoria e independiente del efecto que suponga dicha mutación para la población.…
Growing Like Germany: Local Public Debt, Local Banks, Low Private Investment
2021
The paper uses a panel of more than 1m German firms over 2010-2016, to provide the first firm-bank level evidence of local crowding out for a developed economy characterized by low interest rates and fiscal austerity. Our mechanism relies on two structural features of Germany's banking landscape: the local segmentation of credit markets for small and medium-sized firms (SME) and the role of local public banks in local public finance. Local public banks dominate lending to small and medium firms in Germany and also have an explicit mandate to lend to the local public sector. With spreads on local government debt at all-time lows, local public banks tried to break even, using their market pow…