Upper bound for the conductivity of nanotube networks

Films composed of nanotube networks have their conductivities regulated by the junction resistances formed between tubes. Conductivity values are enhanced by lower junction resistances but should reach a maximum that is limited by the network morphology. By considering ideal ballistic-like contacts between nanotubes we use the Kubo formalism to calculate the upper bound for the conductivity of such films and show how it depends on the nanotube concentration as well as on their aspect ratio. Highest measured conductivities reported so far are approaching this limiting value, suggesting that further progress lies with nanowires other than nanotubes.Comment: 3 pages, 1 figure. Minor changes. Accepted for publication in Applied Physics Letter

Influence of adhesive stiffness on the post-cracking behaviour of CFRP-reinforced structural glass beams

Reinforcement strategies have been developed to prevent catastrophic failures of glass structures after cracking. In this context, the composite action between glass and reinforcement plays a crucial role in the post-cracking performance of glass composite systems. Hence, this paper presents an experimental and numerical investigation on glass-CFRP composite beams manufactured using three different adhesives, with high, intermediate and low stiffness. The experimental programme comprised (i) mechanical characterization tests, (ii) tensile tests on double-lap joints and (iii) flexural tests on composite beams. Moreover, numerical simulations were carried out aiming at providing reliable numerical tools for the design of glass structural elements. Bending tests have shown that it is possible to obtain ductile failure modes in glass elements reinforced with CFRP laminates, sometimes attaining or surpassing the cracking load during the post-cracking phase, depending on the type of adhesive. On the other hand, glass-CFRP composite beams manufactured with stiff, moderate and flexible adhesives were well simulated (i) neglecting the physical existence of the adhesive layer, (ii) assuming the linear elastic behaviour of the adhesive, and (iii) modelling the bond behaviour of the adhesive joint, respectively.This work is financed by the national funds through Fundação para a Ciência e a Tecnologia, IP (FCT), under the grant agreement [SFRH/BD/122428/2016] attributed to the 1st author. This work was partly financed by FCT/MCTES through national funds (PIDDAC) under the R&D Unit Institute for Sustainability and Innovation in Structural Engineering (ISISE), under reference UIDB/04029/2020

Feasibility of mechanical post-tensioning of annealed glass beams by activating externally bonded Fe-SMA reinforcement

The structural concept of post-tensioned glass systems has been investigated to minimize the unpredictable response of structural glass in tension. The Fe-SMAs have been successfully explored for strengthening existing structures due to their advantages in comparison with the conventional reinforcement materials. In particular, the recently developed Fe-17Mn-5Si-10Cr-4Ni-1VC (mass-%) alloy seems sustainable and shows promising properties for the construction industry. This study investigates the feasibility of post-tensioning glass beams by activating externally bonded Fe-SMA strips. The investigation is mainly focussed on (i) the activation process of Fe-SMA strips, with temperatures ranging between 120 °C and 160 °C, and (ii) the advantages of this reinforcement for post-tensioning of glass structural elements, in terms of applicability and structural response. Flexural tests show that it is possible to obtain ductile failure modes when glass beams are reinforced with passive or activated Fe-SMA strips. Activation of Fe-SMA strips resulted in an increase of up to 30 % of the cracking load.The first author wishes to acknowledge the grant SFRH/BD/122428/2016 provided by Fundação para a Ciência e a Tecnologia, IP (FCT), financed by European Social Fund and by national funds through the FCT/MCTES. This work was partly financed by FCT / MCTES through national funds (PIDDAC) under the R&D Unit Institute for Sustainability and Innovation in Structural Engineering (ISISE), under reference UIDB/04029/2020

Desenvolvimento inicial de espécies nativas utilizadas na recuperação de paisagem alterada em Rondônia.

A taxa de sobrevivência de quatro espécies florestais: Colubrina glandulosa (Sobrasil), Hymenaea reticulata (Jatobá), Tabebuia sp. (Ipê amarelo) e Euterpe sp. (açaí) foi avaliada na fase de estabelecimento no campo experimental da Embrapa, em Presidente Médici, Rondônia. O plantio foi realizado em uma área com histórico de uso de pastagem de pelo menos cinco anos, coberta com capim braquiária, na qual foram plantadas as espécies mencionadas observando-se as características do grupo ecológico correspondente em diferentes densidades. Todos os indivíduos receberam numeração de campo. Observou-se que aos 18 meses Colubrina glandulosa apresentou maior taxa de sobrevivência e Hymenaea reticulata o menor ganho em diâmetro de colo, independente da localização no terreno. A média da sobrevivência, levando em conta todas as espécies, foi 71%.bitstream/item/24746/1/ct108-especiesflorestaisnativas.pd

Brain Abscess: a Rare Clinical Case with Oral Etiology

Brain abscess is a very rare condition but has a significant mortality rate. The three main routes of inoculation are trauma, contiguous focus, and the hematogenous route. The odontogenic focus is infrequent and is usually a diagnosis of exclusion. This paper presents a brain abscess case proven to be of dental origin, caused by Actinomyces meyeri and Fusobacterium nucleatum. This case highlights the risk underlying untreated dental disease and why oral infectious foci removal and good oral health are essential in primary care.info:eu-repo/semantics/publishedVersio

Flutuação populacional do percevejo Pachycoris torridus Scopoli, 1772 (Hemiptera: Scutelleridae) em pinhão-manso em Porto Velho, Rondônia.

O presente trabalho objetivou determinar a flutuação populacional do percevejo P. torridus em plantio de pinhão-manso, em Porto Velho, Rondônia.bitstream/item/65100/1/ct121-pinhaomanso.pd

Solubilization and hydrolysis of porcine coagulated blood protein using sub-critical solvent extraction

Pork represents a major fraction of the meat consumed worldwide but only 30% of the blood generated in slaughterhouses is re-used as raw material for food and feed. Innovative technologies and efficient processing strategies capable of generating added-value products from it are now attracting attention. In this study, the hydrolysis of porcine coagulated blood using sub-critical solvent extraction was investigated. Biomass was hydrolyzed using different temperatures (120–210 °C), applying only water (sub-critical water; SCW) or water with a low concentration of alkali (0.1 mol L−1 NaOH) and different reaction times (30–90 min). Resultant hydrolysates were analyzed for crude and soluble protein, peptide profile, and bioactivity by combining protein quantification, antioxidant activity, and fast protein liquid chromatography measurements. Results showed that increasing temperature increases the degree of hydrolysis and that the addition of NaOH enhances the solubilization of peptides with high molecular weights. Also, hydrolysates showed interesting antioxidant activity, being 60 min the time of reaction with best antioxidant activity. Nevertheless, using only water (SCW) as solvent, without chemical additives, allows the delivering of interesting protein-based bioactive fractions. Sub-critical solvent treatment of porcine blood resulted in added-value fractions with potential bioactivities through a simple and environmentally friendly process.info:eu-repo/semantics/publishedVersio

Otimização e validação de método para determinação de ácidos orgânicos em vinhos por cromatografia líquida de alta eficiência.

The organic acids (tartaric, malic, citric, lactic and succinic) are de main components responsible for the acidity in the wine. This method for simultaneous determination of organic acids and interfering peaks in wines can be achieved in 16 min. The sample preceded by a dilution and filtration step. The chromatographic separation required one reversed phase column, isocratic mobile phase (acetonitrila, formic acid in water) and detection wavelength was set at 212 nm. The validation confirmed good repeatability, recovery and application in red and white wines.Nota técnica

Ocorrência e monitoramento de cigarrinha-verde Empoasca sp. (Hemiptera: Cicadellidae) em pinhão-manso no Município de Porto Velho, Rondônia.

O presente trabalho objetivou constatar a ocorrência e monitorar a incidência de cigarrinha-verde Empoasca sp. em plantio de pinhão-manso, em Porto Velho, Rondônia.bitstream/item/57069/1/ct118-cigarrinhaverde.pd