Predicting the fire resistance of timber members loaded in tension

The paper presents a numerical model for predicting the fire resistance of timber members. Fire resistance is evaluated in a two‐step process implemented in the Abaqus finite element code: first, a time‐dependent thermal analysis of the member exposed to fire and then a structural analysis under a constant load are performed. The structural analysis considers the reduction in mechanical properties (modulus of elasticity and strength) of timber with temperature. The analysis terminates when the member can no longer redistribute stresses from the hottest to the coldest parts, leading to structural failure. The model was used to simulate fire tests carried out on specimens made from laminated veneer lumber loaded in tension. Experimental data in terms of temperature, charring depth, displacement and failure time were compared with the numerical results obtained by assuming the thermal properties and degradation of mechanical properties with temperature as suggested by Eurocode 5, showing an overall acceptable approximation. The fire resistance of the timber member was then predicted depending upon the applied tensile loads using the numerical model and analytical formulas. The proposed finite element model can be used to predict the fire resistance of timber structures as an alternative to expensive and complicated experimental tests. Copyright © 2012 John Wiley & Sons, Ltd.     

Biohybrid and Bioinspired Magnetic Microswimmers

Many motile microorganisms swim and navigate in chemically and mechanically complex environments. These organisms can be functionalized and directly used for applications (biohybrid approach), but also inspire designs for fully synthetic microbots. The most promising designs of biohybrids and bioinspired microswimmers include one or several magnetic components, which lead to sustainable propulsion mechanisms and external controllability. This Review addresses such magnetic microswimmers, which are often studied in view of certain applications, mostly in the biomedical area, but also in the environmental field. First, propulsion systems at the microscale are reviewed and the magnetism of microswimmers is introduced. The review of the magnetic biohybrids and bioinspired microswimmers is structured gradually from mostly biological systems toward purely synthetic approaches. Finally, currently less explored parts of this field ranging from in situ imaging to swarm control are discussed.     

PVA/STMP based hydrogels as potential substitutes of human vitreous

PVA based hydrogels were synthesised using, as crosslinking agent, trisodium trimetaphosphate (STMP) to obtain potential substitutes for the vitreous body of the eye. The hydrogels, obtained using different amounts of STMP, were characterised by Infrared Spectroscopy which confirmed the successful occurrence of crosslinking reaction. The mechanical spectra of the fully hydrated samples confirmed covalently crosslinked systems (i.e. G′ > G″). The rheological analysis pointed out that only one of the hydrogels (PVA STMP 8:1) showed a behaviour similar to that of human vitreous. The hydrogel was also subjected to injection through a small needle, a procedure that is essential in the use of vitreous substitutes. Further analysis in terms of light transmittance, water content measurements, diffusion coefficient and cytotoxicity confirmed the applicability of such a hydrogel as vitreous substitute.     

Cultivar and growing area effects on minor compounds of olive oil from autochthonous and European introduced cultivars in Tunisia

BACKGROUND: Antioxidant profile and volatile compounds were characterized in three virgin olive oils from European countries introduced and cultivated under the same orchard conditions in comparison to some autochthonous cultivars planted in different areas of Tunisia. RESULTS: Significant differences were observed between the oils. α‐Tocopherol content is more important in autochthonous Tunisian cultivars (cvs), higher (400 mg kg^?1) than in European cvs. Total phenols showed that Chétoui cv. (grown in Zaghouan) had the highest level (446 mg kg^?1), followed by Koroneiki (403 mg kg^?1) and Chétoui cvs (grown in Béja) (398 mg kg^?1). Koroneiki oils had the highest content of (3,4‐dihydroxyphenyl)ethanol and (p‐hydroxyphenyl)ethanol (20.5 and 43.5 mg kg^?1, respectively), whereas (3,4‐dihydroxyphenyl)ethanol was not detected in Arbequina, Arbosana or Chemlali cvs (grown in Sahel). Chétoui cv. presented the highest content of dialdehydic form of decarboxymethyl elenolic acid linked to (3,4‐dihydroxyphenyl)ethanol (171 mg kg^?1), whereas Chemlali (Sahel) cv. had the lowest content (29.6 mg kg^?1). The volatile compounds showed an increase in C6 compounds and decrease in pentene isomers in olive oils from varieties cultivated in other growing areas. CONCLUSION: Virgin olive oils studied demonstrate that the differences in phenols, tocopherol levels and volatile profiles may be explained by genetic factors and geographic areas, particularly altitude. Copyright © 2009 Society of Chemical Industry     

Thermal Deposition of Intact Tetrairon(III) Single‐Molecule Magnets in High‐Vacuum Conditions

A tetrairon(III) single‐molecule magnet is deposited using a thermal evaporation technique in high vacuum. The chemical integrity is demonstrated by time‐of‐flight secondary ion mass spectrometry on a film deposited on Al foil, while superconducting quantum interference device magnetometry and alternating current susceptometry of a film deposited on a kapton substrate show magnetic properties identical to the pristine powder. High‐frequency electron paramagnetic resonance spectra confirm the characteristic behavior for a system with S = 5 and a large Ising‐type magnetic anisotropy. All these results indicate that the molecules are not damaged during the deposition procedure keeping intact the single‐molecule magnet behavior.     

Advances in single-molecule magnet surface patterning through microcontact printing

We present an implementation of strategies to deposit single-molecule magnets (SMMs) using microcontact printing microCP). We describe different approaches of microCP to print stripes of a sulfur-functionalized dodecamanganese (III, IV) cluster on gold surfaces. Comparison by atomic force microscopy profile analysis of the patterned structures confirms the formation of a chemically stable single layer of SMMs. Images based on chemical contrast, obtained by time-of-flight secondary ion mass spectrometry, confirm the patterned structure.     

Results of radiation tests performed on the ISOCAM infrareddetector array

Extensive radiation tests have been performed on the long-wavelength infrared detector array for the ISOCAM camera, to be launched on the ISO European satellite. Transient and memory effects, induced by γ-rays, protons, and heavy ions have been investigated. Each time a pixel is traversed by a particle, an ionization pulse is generated. The results of different deglitching techniques have been compared. Among them, the half Gauss method seems to be the best. In addition to the transient effect, a memory effect is induced by the radiation: an increase of the photoconductive gain is observed. For 2 rad, the raise in responsivity is about 60%. The relaxation time is the order to 1 h. The relativistic Fe ions present in cosmic rays have been simulated by Ar ions of 70 MeV/nucleon energy. These very heavily ionizing particles induce a large responsivity change, not only in the pixels directly hit by the particles, but also in their neighbors. No permanent damage was observed after irradiation: the initial characteristics were recovered after a few hours and the noise remained unaffected     

Reconciling deep learning and first-principle modelling for the investigation of transport phenomena in chemical engineering

The use of machine learning in chemical engineering has the potential to greatly improve the design and analysis of complex systems. However, there are also risks associated with its adoption, such as the potential for bias in algorithms and the need for careful oversight to ensure the safety and reliability of machine learning-powered systems. This paper explores the opportunities and risks of using machine learning in chemical engineering and provides a perspective on how it may be integrated into engineering practices in a responsible and effective manner. We generated the text of this abstract with GPT-3, OpenAI's large-scale language-generation model. Upon generating the draft, we ensured that the language was to our liking, and we take ultimate responsibility for the content of this publication.     

Changes of solar cell parameters during damp‐heat exposure

The electrical ageing of photovoltaic modules during extended damp‐heat tests at different stress levels is investigated for three types of crystalline silicon photovoltaic modules with different backsheets, encapsulants and cell types. Deploying different stress levels allows determination of an equivalent stress dose function, which is a first step towards a lifetime prediction of devices. The derived humidity dose is used to characterise the degradation of power as well as that of the solar cell's equivalent circuit parameters calculated from measured current–voltage characteristics. An application of this to the samples demonstrates different modes in the degradation and thus enables better understanding of the module's underlying ageing mechanisms. The analysis of changes in the solar cell equivalent circuit parameters identified the primary contributors to the power degradation and distinguished the potential ageing mechanism for each types of module investigated in this paper. © 2016 The Authors. Progress in Photovoltaics: Research and Applications published by John Wiley & Sons Ltd. © 2016 The Authors. Progress in Photovoltaics: Research and Applications published by John Wiley & Sons Ltd.