Applications of an oak extract on Petit Verdot grapevines. Influence on grape and wine volatile compounds

Petit Verdot vineyards were treated at veraison with a commercial aqueous French oak extract in order to determine if the extract’s volatile components can be transferred to grapes and then to wines. Three different formulations (25% (one application), 25% (four applications) and 100%) were tested, together with an eugenol and guaiacol standard solution to better follow their behaviour. The volatile compounds of treated grapes and their wines after alcoholic and malolactic fermentation and after 8 months were analysed by stir bar sorptive extraction and gas chromatography mass spectrometry (SBSE-GC–MS). The results showed that the grapes stored the volatile compounds mainly as non-volatile precursors, and some of these were released after winemaking. In the case of wines, it was possible to distinguish the control versus the ones from vineyard treatments. The different oak extract applications were evident only after alcoholic fermentation sampling, making it very interesting for young wines.     

Influence of the calcination treatment on the catalytic properties of hierarchical ZSM-5

The effect of the calcination conditions on the properties and catalytic performance of hierarchical ZSM-5 zeolite has been investigated using different reactions as catalytic tests: acylation of aromatic substrates and rearrangement of linear and cyclic epoxides. The hierarchical h-ZSM-5 material was prepared by crystallization of silanized protozeolitic units. The removal of the organics present in the as-synthesized ZSM-5 samples has been carried out using two different calcination procedures: (i) directly under air atmosphere; (ii) following a two-step (nitrogen-air) treatment.Clear differences are noticed related to the textural properties of the ZSM-5 samples, since the h-ZSM-5 presents higher BET and external surface area than standard ZSM-5 zeolite. Whereas the calcination method does not affect the properties of the reference ZSM-5 sample, noticeable changes were observed over the hierarchical zeolite. The concentration of Brønsted acid sites decreases by half for one-step air calcination, but only a quarter when using a two-step nitrogen/air calcination, showing that the aluminium present in hierarchical ZSM-5 is very sensitive to the calcination conditions as it may undergo framework extraction and dehydroxylation phenomena. For all the studied reactions, the hierarchical sample, calcined by a two-step treatment, presents higher activity than when using direct air calcination.     

Effect of laser shock processing on fatigue crack growth of duplex stainless steel

Duplex stainless steels have wide application in different fields like the ship, petrochemical and chemical industries that is due to their high strength and excellent toughness properties as well as their high corrosion resistance. In this work an investigation is performed to evaluate the effect of laser shock processing on some mechanical properties of 2205 duplex stainless steel. Laser shock processing (LSP) or laser shock peening is a new technique for strengthening metals. This process induces a compressive residual stress field which increases fatigue crack initiation life and reduces fatigue crack growth rate. A convergent lens is used to deliver 2.5 J, 8 ns laser pulses by a Q-switched Nd:YAG laser, operating at 10 Hz with infrared (1064 nm) radiation. The pulses are focused to a diameter of 1.5 mm. Effect of pulse density in the residual stress field is evaluated. Residual stress distribution as a function of depth is determined by the contour method. It is observed that the higher the pulse density the greater the compressive residual stress. Pulse densities of 900, 1600 and 2500 pul/cm² are used. Pre-cracked compact tension specimens were subjected to LSP process and then tested under cyclic loading with R = 0.1. Fatigue crack growth rate is determined and the effect of LSP process parameters is evaluated. In addition fracture toughness is determined in specimens with and without LSP treatment. It is observed that LSP reduces fatigue crack growth and increases fracture toughness if this steel.     

Characterization of colloidal chromia particles obtained by forced hydrolysis

Colloidal particles of chromia have been prepared by forced hydrolysis of an aqueous solution containing chromium chloride hexahydrate. At elevated temperature, a controlled addition of potassium hydroxide yielded colloidal chromia particles. After the sol coagulation, amorphous dried residues (I) were converted to crystalline form (II) by heating at 1073 K. The thermal treatment was also accompanied by a reduction in both surface area (from 75 to 9 m²/g) and point of zero charge (pH_pzc; from 4.7 to 4.0). Chromia dissolution over the studied pH range (pH=2-12) exhibits a parabolic trend, with minimum solubility at pH_pzc.     

Characterization and material model definition of toughened adhesives for finite element analysis

Some toughened adhesives used for structural joints are characterised by non-linear behaviour prior to failure that may significantly influence the entire joint response. The determination of appropriate and accurate material models for use in analysis and design phases covering both nonlinearities and final material rupture constitutes one of the main challenges for the utilisation of adhesives and for offering designers the same confidence level as that offered by other joining techniques.The present research proposes the utilisation of both elasto-plastic and continuum damage models as a combination that can fully reproduce the mechanical response of toughened adhesives in finite element (FE) analysis. In this context, the Drucker-Prager exponential model has demonstrated to provide accurate fits with the nonlinearities of these materials, allowing the real plastic behaviour of the adhesives to be adjusted in the computational models with a high degree of correlation. On the other hand, a continuum damage model has been proposed to simulate the final material failure process introducing a displacement-based damage parameter into the constitutive equation of the damaged material. The definition of the parameters associated with the mentioned models has been carried out through the execution of an experimental programme combining traction and torsion tests, described in the present paper as part of the study developed. The research is finally completed with an experimental and FE analysis of a specific bonded joint that allows the operation of the material model to be checked in a real application.     

Co catalysts modified by rare earths (La,Ce or Pr) for hydrogen production from ethanol

Co/MgAl₂O₄ catalysts modified with La, Pr or Ce were prepared, characterized by different techniques and tested in ethanol steam reforming reaction to produce hydrogen. The catalytic behavior at 650 °C depended on the nature of rare earth. The amount of carbon on promoted catalysts was significantly lower than that on unpromoted one. The Pr and La containing catalysts produced a high acetaldehyde selectivity which decreased the hydrogen production. The superior performance of the catalyst promoted with 7.8% Ce could be partially explained by a higher dispersion and a high reduction of Co species.     

Electrocatalytic stability of Ti based-supported Pt3Ir nanoparticles for unitized regenerative fuel cells

PtIr (3:1) nanoparticles supported on TiC, TiCN and TiN were investigated as bifunctional electrocatalysts for the oxygen electrode of unitized regenerative fuel cells. The electrocatalysts were prepared by the ethylene glycol method. Physicochemical characterization was carried out by X-ray Diffraction, Transmission Electronic Microscope and X-ray Photoelectron Spectroscopy, meanwhile rotating ring-disk electrode and in situ Fourier transform infrared spectroscopy were employed to determine the electrochemical activity and stability. Results reveal the highest activity toward oxygen reduction and evolution reactions on TiCN-based materials, in addition to the best compromise between catalytic activity and stability. In this context, nitrogen loading appears to be an important factor for the catalyst performance and noble metal anchoring. It is observed an increment of particle agglomeration with nitrogen content in the catalyst support. Also, TiN-based catalyst presents the lowest noble metal inclusion and high passivation degree by dissolved oxygen; whereas TiC and TiCN based catalysts develop an anodic peak at ca. 1.1 V, which is associated to TiO₂ and CO₂ formation.     

Behaviour of Ti-doped CFCs under thermal fatigue tests

In spite of the remarkable progress in the design of in-vessel components for the divertor of the first International Thermonuclear Experimental Reactor (ITER), a great effort is still put into the development of manufacturing technologies for carbon armour with improved properties. Newly developed 3D titanium-doped carbon fibre reinforced composites and their corresponding undoped counterparts were brazed to a CuCrZr heat sink to produce actively cooled flat tile mock-ups. By exposing the mock-ups to thermal fatigue tests in an electron beam test facility, the material behaviour and the brazing between the individual constituents in the mock-up was qualified. The mock-ups with titanium-doped CFCs exhibited a significantly improved thermal fatigue resistance compared with those undoped materials. The comparison of these mock-ups with those produced using pristine NB31, one of the reference materials as plasma facing material for ITER, showed almost identical results, indicating the high potential of Ti-doped CFCs due to their improved thermal shock resistance.     

Evaluation of dehydrated marolo (Annona crassiflora) flour and carpels by freeze-drying and convective hot-air drying

Marolo (Annona crassiflora), an exotic fruit from the Brazilian savanna, has been used for many culinary preparations such as jelly and jam. In this study we have compared physicochemical properties, color analysis, dietary fiber and triacylglycerol analysis of marolo flour and carpels dehydrated by freeze-drying and convective hot-air drying. The experiments were analyzed by Tukey's test (p < 0.05). There was a significant difference between fresh and dehydrated marolo as shown by the analysis of moisture, Aw, and the centesimal composition (except for the ashes).The dehydrated products showed to be sources of alimentary fiber and derivatives from oleic and palmitic acids and can be used during periods between harvests of marolo fruits.