General synthetic approach to 2-phenolic adenine derivatives

A simple and general “one pot” procedure for the synthesis of 2,9-diarylpurines with one or multiple hydroxyl groups in the 2- aryl unit is described, from the reaction of 5-amino-4-amidinoimidazoles with phenolic aldehydes.National NMR Network, Fundação para a Ciência e a Tecnologia (FCT). F.C.T. (project nºF-COMP-01-0124-FEDER-022716 (ref. FCT PEst-/QUI/UI0686/2011) FEDER-COMPETE, FCT-Portugal and the PhD grant to C. Correia (SFRH/BD/22270/2005)

Functionalization of CNTS with maleic anhydride

The outstanding properties of carbon nanotubes (CNTs) [1] are mainly related with their unique structural features. However, the high π-π staking between the tubes is a major drawback for their manipulation and interaction with other materials. Chemical functionalization has been used as a convenient tool to improve their performance in various applications [2]. The work reports the functionalization of multi-wall carbon nanotubes (MWCNTs) with maleic anhydride via a Diels-Alder addition reaction, performed in dimethyl sulfoxide (190 ºC) or 2-chorotoluene (150 ºC) for 24 hours. The product was characterized by thermogravimetric analysis (TGA) and the weight loss at 800 ºC was 11.9 and 3.7 % respectively. Potentiometric titration suggests that CNTs modified at 190 ºC remain predominantly in the anhydride form, while for CNTs modified at 150 ºC, the extent of hydrolysis is approximately 40 %. Maleic anhydride was also reacted with a model compound (anthracene) in dimethyl sulfoxide (190 ºC) and the hydrolysis of the product (0.025 mmol in 650 µL of DMSO-d6) was followed by 1H RMN upon addition of 0.166 mmol of DCl (40 % weight in D2O) (graphic in figure). The anhydride 1 was easily regenerated from the dicarboxylic acid 2 when this compound was heated at 185 ºC for 10 minutes. A similar behavior is expected for the modified CNTs.Fundação para a Ciência e Tecnologi

Few-layer graphene aqueous suspensions for polyurethane composite coatings

Graphite nanoplates (GnP) have recently attracted attention as an economically viable alternative for the development of functional and structural nanocomposites. The incorporation of GnP into waterborne polyurethane (WPU) with loadings from 0.1 to 10 wt.% was studied. The mechanical properties of the composite films were assessed by tensile testing showing an increase of the Young’s modulus up to 48%. The electrical conductivity increased by 9 orders of magnitude and the water vapor permeability of the composite films decreased 57% for composites containing 5.0 wt.% of GnP.The authors acknowledge FCT, project PEst-C/CTM/LA0025/2015 and PhD grant SFRH/BD/87214/2012.info:eu-repo/semantics/publishedVersio

Desenvolvimento de um Repositório de Imagens e Base de Dados Portuguesa de Casos COVID-19: Aprendizagem e Partilha de Conhecimento em Tempo de Pandemia

info:eu-repo/semantics/publishedVersio

Electrochemical sensing using carboxylated multiwalled carbon nanotubes

Carbon nanotubes (CNTs) have demonstrated great advantages in electrochemistry. The application of CNTs most widely employed so far has been the construction of various detection devices, such as gas sensors, electrochemical detectors and biosensors [1]. The main advantage of their use is related to the increase of the electrodes surface area and of the electron transfer rates, improving sensors sensitivity. Besides, their sorption capability of different analytes can be used to improve sensors selectivity [2]. (...

New Concepts In White Adipose Tissue Physiology.

Numerous studies address the physiology of adipose tissue (AT). The interest surrounding the physiology of AT is primarily the result of the epidemic outburst of obesity in various contemporary societies. Briefly, the two primary metabolic activities of white AT include lipogenesis and lipolysis. Throughout the last two decades, a new model of AT physiology has emerged. Although AT was considered to be primarily an abundant energy source, it is currently considered to be a prolific producer of biologically active substances, and, consequently, is now recognized as an endocrine organ. In addition to leptin, other biologically active substances secreted by AT, generally classified as cytokines, include adiponectin, interleukin-6, tumor necrosis factor-alpha, resistin, vaspin, visfatin, and many others now collectively referred to as adipokines. The secretion of such biologically active substances by AT indicates its importance as a metabolic regulator. Cell turnover of AT has also recently been investigated in terms of its biological role in adipogenesis. Consequently, the objective of this review is to provide a comprehensive critical review of the current literature concerning the metabolic (lipolysis, lipogenesis) and endocrine actions of AT.47192-20

Influence of the feedstock material on the compost maturity, stability and reactivity

Compost samples from different origins have been characterized in order to obtain information about their composition, humic-like substances content, maturity and stability. The composts used in the present study were obtained from manure (CAP), algae (CA), domestic waste (VCRU), sewage sludge (CT) and animal waste (CE). Different techniques have been used to gather physical-chemical parameters of the raw composts, their equilibrium solutions and the extracted humic-like substances. The analysis of the parameters collected in the characterization process allowed to stablish the degree of maturity and stability of the composts. Results indicate that the compost originated from algae exhibits the highest degree of maturity. Also, metal complexation was analyzed in the CE compost with the aim of assessing the contribution of the different fractions of dissolved organic matter.0366_RES2VALHUM_1_P - Valorização de resíduos orgânicos: produção de substâncias húmicas, cofinanciada pelo Fundo Europeu de Desenvolvimento regional (FEDER) através do Programa INTERREG V-A Espanha-Portugal (POCTEP) 2014-2020