Comparative life cycle assessment of high-yield synthesis routes for carbon dots

Carbon dots (CDs) are carbon-based nanomaterials with advantageous luminescent properties, making them promising alternatives to other molecular and nanosized fluorophores. However, the development of CDs is impaired by the low synthesis yield of standard fabrication strategies, making high-yield strategies essential. To help future studies to focus on cleaner production strategies, we have employed a Life Cycle Assessment (LCA) to compare and understand the environmental impacts of available routes for the high-yield synthesis of carbon dots. These routes were: (1) production of hydrochar, via hydrothermal treatment of carbon precursors, and its alkaline-peroxide treatment into high-yield carbon dots; (2) thermal treatment of carbon precursors mixed in a eutectic mixture of salts. Results show that the first synthesis route is associated with the lowest environmental impacts. This is attributed to the absence of the mixture of salts in the first synthesis route, which offsets its higher electricity consumption. Sensitivity analysis showed that the most critical parameter in the different synthetic strategies is the identity of the carbon precursor, with electricity being also relevant for the first synthesis route. Nevertheless, the use of some carbon precursors (as citric acid) with higher associated environmental impacts may be justified by their beneficial role in increasing the luminescent performance of carbon dots. Thus, the first synthesis route is indicated to be the most environmental benign and should be used as a basis in future studies aimed to the cleaner and high-yield production of carbon dots

Post-fire survival and regeneration of Eucalyptus globulus in forest plantations in Portugal

Eucalyptus globulus is one of the most important pulpwood plantation species in the world, and nowadays it is present in most continents. Some of the regions where E. globulus plantations have been expanding have a high incidence of wildfires; therefore, knowing the factors affecting the fire resistance and resilience of this species is particularly important for forest management. This is the case of Portugal, where nearly 1.4 million ha of land burned in the last decade and where E. globulus has become the most widespread tree species. In this paper we assessed the short-term post-fire responses of E. globulus trees in four sites affected by wildfires, and investigated their potential relationships with fire severity descriptors and with tree and stand characteristics. One year after fire, individual tree mortality was low (3.9%) but most trees (79.2%) were top-killed (i.e. had stem mortality). Both post-fire tree mortality and top-kill increased with fire severity (expressed by maximum char height and/or char severity rating). Moreover, top-kill was positively related with vegetation cover and the proportion of pine trees in the stand, and was negatively related with tree diameter and the proportion of other broadleaved trees in the stand. The most common post-fire regeneration type among the sampled trees was basal resprouting (89.2%), though 20.9% had epicormic resprouting. The number of basal resprouts increased with char height, top-kill and diameter of the parent tree, and decreased with slope. In terms of post-fire growth, the height of the dominant resprout increased with the number of resprouts and with char severity, while it decreased in drier southern aspects. Results showed that E. globulus is a fire-resilient species with a very high probability of surviving fire; however, in forest plantations where trees are usually felled in short rotations (thus with limited size), individuals have a high probability of being top-killed. The presented models may be useful to help managers on the assessment of post-fire production losses and regeneration potential in E. globulus plantation

Química no cotidiano: a química dos alimentos e a tabela periódica

O tema Tabela Periódica foi abordado no presente trabalho através de um projeto apresentado em uma Mostra de Ciências de uma Escola de ensino básico no Município do Rio de Janeiro. Neste projeto o teor qualitativo de vitamina C de alguns sucos de fruta (abacaxi, laranja e morango) foi determinado por dosagem com iodo. Uma avaliação da familiaridade do público com a Tabela Periódica e sua importância na compreensão dos diferentes elementos químicos presentes nos alimentos foi realizada através de um questionário. Os resultados demonstram que o público em geral tem conhecimentoda existência da Tabela Periódica, mas não é capaz de associa-la com a composição química dos alimentos. O projeto estimulou o interesse dos participantes na busca por um conhecimento mais detalhado das informações que a Tabela Periódica pode disponibilizar em relação à dieta alimentar

Matrix Converter-Based Unified Power-Flow Controllers: Advanced Direct Power Control Method

This paper presents a direct power control (DPC) for three-phase matrix converters operating as unified power flow controllers (UPFCs). Matrix converters (MCs) allow the direct ac/ac power conversion without dc energy storage links; therefore, the MC-based UPFC (MC-UPFC) has reduced volume and cost, reduced capacitor power losses, together with higher reliability. Theoretical principles of direct power control (DPC) based on sliding mode control techniques are established for an MC-UPFC dynamic model including the input filter. As a result, line active and reactive power, together with ac supply reactive power, can be directly controlled by selecting an appropriate matrix converter switching state guaranteeing good steady-state and dynamic responses. Experimental results of DPC controllers for MC-UPFC show decoupled active and reactive power control, zero steady-state tracking error, and fast response times. Compared to an MC-UPFC using active and reactive power linear controllers based on a modified Venturini high-frequency PWM modulator, the experimental results of the advanced DPC-MC guarantee faster responses without overshoot and no steady-state error, presenting no cross-coupling in dynamic and steady-state responses

Direct Power Control of Matrix Converter Based Unified Power Flow Controllers

This paper presents the Direct Power Control of Three-Phase Matrix Converters (DPC-MC) operating as Unified Power Flow Controllers (UPFC). Since matrix converters allow direct AC/AC power conversion without intermediate energy storage link, the resulting UPFC has reduced volume and cost, together with higher reliability. Theoretical principles of DPC-MC method are established based on an UPFC model, together with a new direct power control approach based on sliding mode control techniques. As a result, active and reactive power can be directly controlled by selection of an appropriate switching state of matrix converter. This new direct power control approach associated to matrix converters technology guarantees decoupled active and reactive power control, zero error tracking, fast response times and timely control actions. Simulation results show good performance of the proposed system

Toxicological Study Employing Repeated Doses of Garcinielliptone FC, a Polyisoprenylated-Benzophenone Isolated from Seed of Platonia Insignis Mart

The major constituent from the hexane extract of the seeds of P. insignis is GFC (garcinielliptone FC). Doses of 25, 50and 75 mg/kg of GFC were aseptically suspended in 0.05% Tween 80 dissolved in 0.9% saline (vehicle) and orally administered for30, 90 and 120 consecutive days to adult Swiss mice. In this work, the repeated oral administration, in animals of both sexes,demonstrates that this compound is not able to induce mortality and/or behavioral changes in adult mice. In addition, body weightgain, feed intake and disposal of excreta were not altered by the administration of this compound with repeated doses. Furthermore,no differences in weight and macroscopic structure of the brain, liver, kidney, lung, heart and spleen between groups of male andfemale adult mice were observed after treatment. During the periods of treatment, GFC produced no significant changes onhaematological and biochemical parameters in male and female mice treated with all doses used. The aim of this study was toinvestigate the toxicological potential of GFC through behavioral, hematological, biochemical and morphological parameters inanimals in order to ensure the safe use of Platonia insignis in folk medicine.Fil: Silva, Ana P.. Federal University of Piauí; BrasilFil: Filho, José Carlos C. L. S.. North Union of Parana; BrasilFil: da Costa Júnior, Joaquim S.. Federal Institute of Piauí; BrasilFil: Peláez, Walter José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Faillace, Martín Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Falcão Ferraz, Alexandre de B.. Lutheran University of Brazil; BrasilFil: David, Jorge M.. Institute Of Chemistry, Federal University Of Bahia; Brasil. Universidade Federal da Bahia; BrasilFil: Freitas, Rivelilson M.. Federal University of Bahia; Brasi

Scaffolds and Coatings for Bone Regeneration

Bone tissue has an astonishing self-healing capacity yet only for non-critical size defects (<6â mm) and clinical intervention is needed for critical-size defects and beyond that along with non-union bone fractures and bone defects larger than critical size represent a major healthcare problem. Autografts are, still, being used as preferred to treat large bone defects. Mostly, due to the presence of living differentiated and progenitor cells, its osteogenic, osteoinductive and osteoconductive properties that allow osteogenesis, vascularization, and provide structural support. Bone tissue engineering strategies have been proposed to overcome the limited supply of grafts. Complete and successful bone regeneration can be influenced by several factors namely: the age of the patient, health, gender and is expected that the ideal scaffold for bone regeneration combines factors such as bioactivity and osteoinductivity. The commercially available products have as their main function the replacement of bone. Moreover, scaffolds still present limitations including poor osteointegration and limited vascularization. The introduction of pores in scaffolds are being used to promote the osteointegration as it allows cell and vessel infiltration. Moreover, combinations with growth factors or coatings have been explored as they can improve the osteoconductive and osteoinductive properties of the scaffold. This review focuses on the bone defects treatments and on the research of scaffolds for bone regeneration. Moreover, it summarizes the latest progress in the development of coatings used in bone tissue engineering. Despite the interesting advances which include the development of hybrid scaffolds, there are still important challenges that need to be addressed in order to fasten translation of scaffolds into the clinical scenario. Finally, we must reflect on the main challenges for bone tissue regeneration. There is a need to achieve a proper mechanical properties to bear the load of movements; have a scaffolds with a structure that fit the bone anatomy.This article is a result of the project FROnTHERA(NORTE-01-0145-FEDER-000023), supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the POR-TUGAL 2020 Partnership Agreement, through the European RegionalDevelopment Fund (ERDF) and is supported by Portuguese Founda-tion for Science and Technology in the scope of the projects UID/EEA/04436/2013 and NORTE-01-0145-FEDER-000018-HAMaBICo. JMOthanks the Portuguese Foundation for Science and Technology (FCT)for the funds provided under the program Investigador FCT 2015 (IF/01285/2015)

Disparate faculty perspectives on system changes in higher education

Higher education (HE) systems around the world have experienced profound structural changes, particularly since the late 1960s to early 1970s, essentially driven by the need to expand access to tertiary education. This has resulted in a diversity of HE institutions (HEI) with different roles, missions and statuses, as well as academic staff with diverse perspectives and motivations. The present study is based on a survey undertaken in Portugal by a trade union, which aimed to collect faculty perspectives on a proposed HE reform sent out for public discussion by the government. Questions addressed the reorganization of the HEI network, the internal restructuring of HEI, the funding system and the binary divide of HEI (universities and polytechnics). The survey results showed a disparity of faculty perspectives about the proposed reform, closely related to the diversity of HEI. Respondents from lower academic categories and from smaller HEI were more opposed to reorganizing the HEI network. This reorganization was more widely accepted by university staff, who were also more in favour of a binary system than were polytechnic respondents. Although there was general agreement about the need to change the funding system, polytechnic respondents were strongly against a funding differentiation between universities and polytechnics. Despite an overall reformist trend, the enthusiasm for reforms declined substantially when the questions had a direct reference to the respondent’s region or institution. It is argued that HE expansion has driven the diversification of HEI, leading to a range of perspectives about the HE system and the way it should be changed. These conclusions may contribute to insights into other HE systems around the world where institutional diversification has been sought by public policies.The authors are grateful to Jennifer Burdon, Tania Stadler and Matthew Larcombe for the English revision of the manuscript. Adelaide Freitas was supported by CIDMA - Center for Research & Development in Mathematics and Applications, and FCT - Portuguese Science Foundation, within project UID/MAT/04106/2013.publishe

Regeneration of the intervertebral disc

Degeneration of intervertebral disc (IVD) seems to be one of the main causes associated to lower back pain (LBP), one of the most common painful conditions that lead to work absenteeism, medical visits, and hospitalization in actual society [1,2]. This complex fibro-cartilaginous structure is composed by two structures, an outer multilayer fiber structure (annulus fibrosus, AF) and a gel-like inner core (nucleus pulposus, NP), which are sandwiched in part between two cartilage endplates (CEP) [1]. Existing conservative and surgical treatments for LBP are directed to pain relief and do not adequately restore disc structure and mechanical function [2]. In the last years, several studies have been focusing on the development of tissue engineering (TE) approaches aiming to substitute/regenerate the AF or NP, or both by developing an artificial disc that could be implanted in the body thus replacing the damaged disc [3]. TE strategies aiming to regenerate NP tissue often rely on the use of natural hydrogels, due to the number of advantages that these highly hydrated networks can offer. Nevertheless, several of the hydrogel systems developed still present numerous problems, such as variability of production, and inappropriate mechanical and degradation behaviour. Recently, our group has proposed the use of gellan gum (GG) and its derivatives, namely the ionic- and photo-crosslinked methacrylated gellan gum (GG-MA) hydrogels, as potential injectable scaffolds for IVD regeneration [4,5]. Work has been conducted regarding the improvement of GG mechanical properties either by chemically modifying the polymer (allowing to better control in situ gelation and hydrogel stability) [4] or by reinforcing it with biocompatible and biodegradable GG microparticles (enabling the control of degradation rate and cell distribution) [5]. Another strategy currently under investigation relies on the development of a biphasic scaffold that mimics the total disc by using a reverse engineering approach

The influence of structure and surface chemistry of carbon materials on the decomposition of hydrogen peroxide

Carbon materials with different structural and chemical properties, namely activated carbons, carbon xerogels, carbon nanotubes, graphene oxide, graphite and glycerol-based carbon materials, were tested under different operating conditions for their ability to catalyse hydrogen peroxide (H2O2) decomposition in aqueous solutions. Activated carbons treated with concentrated sulphuric acid (ACS) are the most active catalytic materials for H2O2 decomposition in most of the conditions studied, due to the presence of sulphur containing functional groups at their surface. In addition, ACS proved to be a stable catalyst in reutilization tests for H2O2 decomposition. Methanol was used as selective scavenger of hydroxyl radicals (HO center dot), to show that activated carbons with a markedly basic character lead to the highest yield of HO center dot formed during the H2O2 decomposition process (14%, after 150 min of reaction). Overall, from the mechanistic interpretation of H2O2 decomposition, it is concluded that the presence of sulphur containing functional groups at the surface of the activated carbons improves the removal of H2O2 in aqueous solutions, but, on the other hand, the selective decomposition of H2O2 via HO center dot formation is enhanced by the presence of basic active sites on the Carbon surface