MODE I FRACTURE CHARACTERIZATION: WOOD SEN-TPB

The single edge notched beam loaded in three-point-bending (SEN-TPB) was used in this study to induce mode I fracture in wood (Picea abeas L.). Numerical analyses of stress profiles along the specimen length revealed a stress relief region as crack grows in size. Based on this data, beam theory and crack equivalent concepts were employed to develop an expedite data reduction scheme to estimate the Resistance-curve, taking advantage of a simplification performed on the revealed stress relief region. Besides allowing the evaluation of wood fracture toughness without crack length monitoring during loading, the developed procedure provides a user-friendly method when compared to other sophisticated procedures. Experiments involving the SEN-TPB were performed to evaluate fracture toughness in wood

Establishment of a new PNA-FISH method for Aspergillus fumigatus identification: first insights for future use in pulmonary samples

Aspergillus fumigatus is the main causative agent of Invasive Aspergillosis. This mold produces conidia that when inhaled by immunocompromized hosts can be deposited in the lungs and germinate, triggering disease. In this paper, the development of a method using peptide nucleic acid-fluorescence in situ hybridization (PNA-FISH) is described. The PNA-FISH probe was tested in several strains and a specificity and sensitivity of 100% was obtained. Detection of A. fumigatussensu stricto was then achieved in artificial sputum medium (ASM) pre-inoculated with 1 × 102 conidia·mL−1–1 × 103 conidia·mL−1, after a germination step of 24 h. The PNA-FISH method was evaluated in 24 clinical samples (10 sputum, 8 bronchoalveolar lavage (BAL), and 6 bronchial lavage (BL)) that were inoculated with 1 × 104 conidia·mL−1 in sputum; 1 × 103 conidia·mL−1 in BL and BAL, for 24 h. Despite a specificity of 100%, the sensitivity was 79%. This relatively low sensitivity can be explained by the fact that hyphae can yield “fungal ball“ clusters, hindering pipetting procedures and subsequent detection, leading to false negative results. Nonetheless, this study showed the potential of the PNA-FISH method for A. fumigatussensu stricto detection since it takes only 1 h 30 m to perform the procedure with a pre-enrichment step of 6 h (pure cultures) and 24 h (clinical samples), and might provide a suitable alternative to the existing methods for studies in pure cultures and in clinical settings.This research was funded by: Base Funding — UIDB/00511/2020 of the Laboratory for Process Engineering, Environment, Biotechnology and Energy—LEPABE—funded by national funds through the FCT/MCTES (PIDDAC)—Projects POCI-01-0145-FEDER-029961 and POCI-01-0145-FEDER-031011, funded by FEDER funds through COMPETE2020—Programa Operacional Competitividade e Internacionalização (POCI) and by national funds (PIDDAC) through FCT/MCTES. Laura Cerqueira is also financed by Project POCI-01-0145-FEDER-029961.info:eu-repo/semantics/publishedVersio

Numerical and experimental characterization of Steel - Wood doweled joints under Quasi-Static loading

The objective of this work is to investigate the quasi-static mechanical behaviour of doweltypetimber joints. Therefore, four dowel arrangements were experimentally tested to assurethe stability of a steel-wood joint. The results revealed different behaviour regarding thedistance between dowels and distance to the free edge of the wood member. An approachbased on cohesive zone modelling was adopted to replicate both the ductile and brittle failureobserved in the experiments

Al2O3 ultra-thin films deposited by PEALD for rubidium optically pumped atomic magnetometers with on-chip photodiode

This communication shows the recipe for plasma-enhanced atomic layer deposition (PEALD) Al2O3 ultra-thin films with thicknesses below 40 nm. Al2O3 ultra-thin films were deposited by PEALD to improve the rubidium optically pumped atomic magnetometers’ (OPMs) cell lifetime. This requirement is due to the consumption of the alkali metal (rubidium) inside the vapor cells. Moreover, as a silicon wafer was used, an on-chip photodiode was already integrated into the fabrication of the OPM. The ALD parameters were achieved with a GPC close to 1.2 Å/cycle and the ALD window threshold at 250 °C. The PEALD Al2O3 ultra-thin films showed a refractive index of 1.55 at 795 nm (tuned to the D1 transition of rubidium for spin-polarization of the atoms). The EDS chemical elemental analysis showed an atomic percentage of 58.65% for oxygen (O) and 41.35% for aluminum (Al), with a mass percentage of 45.69% for O and 54.31% for Al. A sensitive XPS surface elemental composition confirmed the formation of the PEALD Al2O3 ultra-thin film with an Al 2s peak at 119.2 eV, Al 2p peak at 74.4 eV, and was oxygen rich. The SEM analysis presented a non-uniformity of around 3%. Finally, the rubidium consumption in the coated OPM was monitored. Therefore, PEALD Al2O3 ultra-thin films were deposited while controlling their optical refractive index, crystalline properties, void fraction, surface roughness and thickness uniformity (on OPM volume 1 mm × 1 mm × 0.180 mm cavity etched by RIE), as well as the chemical composition for improving the rubidium OPM lifetime.This work was supported by project MME reference 105399; CMEMS-UMinho Strategic Project UIDB/04436/2020 and UIDP/04436/2020; Infrastructures Micro&NanoFabs@PT, NORTE-01-0145-FEDER-022090, Portugal 2020; and MPhotonBiopsy, PTDC/FIS-OTI/1259/2020

Wood beam repairing with carbon-epoxy composites

Wood damaged beams submitted to bending loads were repaired using carbon-epoxy patches. The effect of patch thickness as well as adhesive filleting were both studied experimentally and numerically. The objective was to verify the influence of these aspects on the strength and failure of the repaired structural components. Cohesive zone modeling considering mixedmode (I+II) loading was carried out to simulate the observed experimental behavior. It was concluded that repair can successful recover the original bearing capacity, although patch thickness and adhesive filleting did not reveal a significant gain on strength

Conjugated linoleic acid reduces permeability and fluidity of adipose plasma membranes from obese Zucker rats

NOTICE: this is the author’s version of a work that was accepted for publication in Biochemical and Biophysical Research Communications. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Biochemical and Biophysical Research Communications. July 2010; 398 (2): 199-204.Conjugated linoleic acid (CLA) is a dietary fatty acid frequently used as a body fat reducing agent whose effects upon cell membranes and cellular function remain unknown. Obese Zucker rats were fed atherogenic diets containing saturated fats of vegetable or animal origin with or without 1% CLA, as a mixture of cis(c)9,trans(t)11 and t10,c12 isomers. Plasma membrane vesicles obtained from visceral adi- pose tissue were used to assess the effectiveness of dietary fat and CLA membrane incorporation and its outcome on fluidity and permeability to water and glycerol. A significant decrease in adipose membrane fluidity was correlated with the changes observed in permeability, which seem to be caused by the incor- poration of the t10,c12 CLA isomer into membrane phospholipids. These results indicate that CLA supple- mentation in obese Zucker rats fed saturated and cholesterol rich diets reduces the fluidity and permeability of adipose membranes, therefore not supporting CLA as a body fat reducing agent through membrane fluidification in obese fat consumers

Improving the sensing ability of thiazolothiazole derivatives towards metal ions

Funding Information: N. Moura thanks FCT for funding through program DL 57/2016 – Norma transitória (REF.-048-88-ARH/2018). Publisher Copyright: © 2024 The Author(s)Two non-symmetrical thiazolothiazoles (TzTz) incorporating pyridin-2-yl groups were synthesized and their sensing abilities towards a series of metal ions were evaluated. The new compounds exhibited good sensing capabilities towards Cu2+ and Zn2+, enabling the differentiation between these two metal ions through spectrophotometric and spectrofluorimetric titrations. The addition of other metal ions to these TzTz derivatives does not cause noticeable effects. The results of this study highlight the high potential of TzTz derivatives for metal ions detection applications.publishersversionpublishe

The mechanism of formate oxidation by metal-dependent formate dehydrogenases

J Biol Inorg Chem (2011) 16:1255–1268 DOI 10.1007/s00775-011-0813-8Metal-dependent formate dehydrogenases (Fdh) from prokaryotic organisms are members of the dimethyl sulfoxide reductase family of mononuclear molybdenum-containing and tungsten-containing enzymes. Fdhs catalyze the oxidation of the formate anion to carbon dioxide in a redox reaction that involves the transfer of two electrons from the substrate to the active site. The active site in the oxidized state comprises a hexacoordinated molybdenum or tungsten ion in a distorted trigonal prismatic geometry. Using this structural model, we calculated the catalytic mechanism of Fdh through density functional theory tools. The simulated mechanism was correlated with the experimental kinetic properties of three different Fdhs isolated from three different Desulfovibrio species. Our studies indicate that the C–H bond break is an event involved in the rate-limiting step of the catalytic cycle. The role in catalysis of conserved amino acid residues involved in metal coordination and near the metal active site is discussed on the basis of experimental and theoretical results

Porphyrin-silica gel hybrids as effective and selective copper(II) adsorbents from industrial wastewater

Porphyrins are an important class of ligands with a tremendous ability to capture metal ions closely related to the rich coordination chemistry of porphyrins. Herein we use this characteristic to develop silica gel grafted derivatives for water remediation applications. Therefore, two porphyrin derivatives, one with three and the other with four mercaptopyridyl units were grafted on silica gel functionalized with 3-aminopropyltriethoxysilane. The new adsorbents Si3PyS and Si4PyS were characterized using a suitable set of techniques confirming the covalent attachment of the porphyrins to the silica surface. Additionally, microscopy and N2 adsorption analysis confirmed the structural integrity and preservation of the mesoporous structure of Si during surface modification. The results show that both hybrid materials exhibit good chemical and thermal stability and an outstanding Cu2+ removal capability, with a chemical adsorption capacity of 176.32 mg g–1 and 184.16 mg g–1, respectively. These materials have also been used in real water and industrial wastewater samples with minimal interference in their adsorption capabilities. Density Functional Theory calculations were performed to confirm the good performance of the hybrid materials Si3PyS and Si4PyS towards metal ions. The functionalization of silica surface with porphyrin-based ligands bearing additional binding motifs drastically improves the adsorption capability of the new hybrids towards metal ions. The presence of pyridyl units brings a meaningful advantage, since both porphyrin core and appended pyridyl groups are able of binding Cu2+ ions with high affinity, contributing to the enhancement of the chelating features of the adsorbents prepared when compared with other ligands supported in silica-based materials.publishe