Durability and chromatic behavior in cement pastes containing ceramic industry milling and glazing by-products

The decay in mortar and concrete induced by extremely aggressive agents is normally the result of the agent-binder reaction. Cement composition and characteristics therefore determine the durability of the mortars and concretes of which they form part. The existing legislation envisages the use of different types of additions in cement, which have a direct effect on the durability of elements in buildings and civil works. This study addressed the inclusion of ceramic industry milling and glazing sludge as an active addition in cement. The reuse of this industrial waste is consistent with environmental policies that seek to reduce or eliminate spoil heaps by recycling industrial waste and byproducts as raw materials, in keeping with circular economy principles. The research conducted makes an innovative contribution to the valorization of this waste, and highlights the resistance of blended cement pastes to chemical agents, further to the Koch-Steinegger method. Water-induced decay in freeze/thaw situations was also studied. The processes involved were identified by analyzing the mineralogical variations detected with X-ray diffraction, the morphological alterations observed with scanning electron microscopy and the mercury porosimetric findings on pore size distribution. The suitability of these binders for aesthetically demanding applications was also explored by measuring the color in pastes exposed to aggressive chemical agents. For the first time, a correlation was established between color parameters and the formation of the reaction products generated during chemical attack.     

Vertical and horizontal integration systems in Industry 4.0

Wireless Networks - Industrial and technological growth, sponsored by the new organizational systems generated by the fourth industrial revolution, require adapt new business management ways in the...     

Borehole stability analysis considering spatial variability and poroelastoplasticity

Typically, stability analysis of oil-producing wells is carried out considering that both the hydraulic and mechanical parameters of the rock mass are deterministic. When analyzing borehole stability, two failure mechanisms are generally considered, namely, failure due to either tensile or compressive (shear) stresses. These mechanisms are produced, respectively, by either too high or too low drilling fluid pressure. Mechanical and hydraulic properties of rock masses, and in particular sedimentary rock masses, may show a considerable degree of spatial variability. This paper focuses on the evaluation of the limits for the internal pressure associated with a target probability of failure, taking into account both the spatial variability of hydraulic and mechanical properties, and the simple variability of the initial pore pressure and in-situ stresses. The analysis is performed with a finite element program that incorporates coupled fluid-mechanical effects and elastoplastic behavior of the rock. In this way, the proposed borehole stability analysis can be set into a reliability-based framework described in the paper. Examples are shown, using stochastic data from the literature, and conclusions are drawn regarding the effect of spatial variability on the borehole stability.     

Characterization of phenolics by LC-UV/vis, LC-MS/MS and sugars by GC in Melicoccus bijugatus Jacq. 'Montgomery' fruits

Fruits of the native South American tree Melicoccus bijugatus Jacq. (Sapindaceae) are consumed for both dietary and medicinal purposes, but limited information is available about the phytochemistry and health value of M. bijugatus fruits. Fruit tissues of the Florida Montgomery cultivar were assessed for sugars, using gas chromatography, and for total phenolics, using UV spectroscopy. Reverse phase high performance liquid chromatography (HPLC) fingerprints of crude methanolic pulp, embryo and seed coat extracts were obtained at 280 nm. Phenolics were characterised by both HPLC UV/vis analysis and HPLC electrospray ionization tandem mass spectrometry. Major sugars detected in the pulp and embryo extracts were sucrose, followed by glucose and fructose. The glucose:fructose ratio was 1:1 in the pulp and 0.1:1 in the embryo. Total phenolic concentrations of the fruit tissues were in the order: seed coat > embryo > pulp. Phenolic acids were identified mostly in pulp tissues. Phenolic acids, flavonoids, procyanidins and catechins were identified in embryo tissues, and higher molecular weight procyanidins were identified in seed coat tissues. This study provides new information about the phytochemistry and the potential health value of the Montgomery cultivar M. bijugatus fruit tissues.     

Experimental verification of various methods for biological hydrogen production

The aim of the work was to compare two different biological methods for hydrogen production: fermentative and photosynthetic based upon the modality of batch cultures. For testing of fermentative bio-hydrogen production four mixed cultures representing anaerobic microorganisms (dominant strain Clostridium) were selected. The kinetic parameters on the intensity of bio-hydrogen production were established. The efficiency coefficient of transformation ranged from 1.65 mol H₂/mol glucose in the pectin culture up to 2.45 in the mixed culture. The bio-hydrogen concentration never exceeded 30%. The carbon dioxide was produced in a ratio of CO₂ to H₂ (0.5–0.67)/1. The testing of green algae proved that the most effective was the algae species Scenedesmus. High bio-hydrogen purity was analytically verified. The fermentative method of H₂ production is more efficient; it does not need light, has a longer efficiency of one charge and enables effective use of different biological wastes.     

Investigation of the preparation and activity of gold catalysts in the total oxidation of n-hexane

The factors affecting the preparation of Au/TiO₂ catalysts and their activity in the total oxidation of n-hexane were investigated. The mechanism of gold deposition–precipitation is discussed through comparison of the samples prepared by this method and others prepared by anion adsorption method. The influence of the pH and of the origin of TiO₂ support used are additionally addressed. The difference of gold dispersion observed between the two methods is attributed to a difference of mobility of the gold precursors during the thermal treatment rather than to a difference of dispersion over the uncalcined samples. The mechanism of gold deposition–precipitation actually involves the reactions of gold hydroxy-chloride species with the surface. Another part of the work, thus, concerned the use of the deposition–precipitation method to prepare a Au/MnO₂ catalyst. It is shown that the activity of γ-MnO₂ is directly proportional to its surface area and that the deposition–precipitation procedure decreases the surface and activity of MnO₂. However, the deposition of gold allows to avoid a too deep sintering of γ-MnO₂ and, thus, helps to somehow preserve its activity.     

Mycotic sinusitis

Previous drug discrimination studies have elucidated the importance of gamma-aminobutyric acidA (GABAA), N-methyl-D-aspartate (NMDA) glutamate, and serotonin (5-HT) receptor systems in mediating the discriminative stimulus effects of ethanol. The present study used a three-choice operant drug discrimination procedure in an attempt to determine if salient GABAergic effects could be separated from other stimulus effects of 2.0 g/kg ethanol. Adult male Long-Evans rats (n = 7) were trained to discriminate pentobarbital (10.0 mg/kg; intragastrically (i.g.) from ethanol (2.0 g/kg; i.g.) from water (4.7 ml; i.g.) using food reinforcement. Stimulus substitution tests were conducted following the administration of allopregnanolone (1.0-17.0 mg/kg; intraperitoneally (i.p.)), diazepam (0.1-7.3 mg/kg; i.p.), midazolam (0.0056-17.0 mg/kg; i.p.), dizocilpine (0.01-0.56 mg/kg; i.p.), phencyclidine (1.0-5.6 mg/kg; i.p.), CGS 12066B (3-30 mg/kg; i.p.), RU 24969 (0.1-5.6 mg/kg; i.p.) and morphine (1 or 3.0 mg/kg; i.p.). Within the group, allopregnanolone and midazolam completely substituted (> 80%), and diazepam partly substituted (67%) for the discriminative stimulus effects of pentobarbital. Dizocilpine and phencyclidine partly substituted (58 and 57%, respectively) for ethanol without substantial pentobarbital-appropriate responding. RU 24969, CGS 12066B and morphine did not result in complete substitution for either ethanol or pentobarbital, although RU 24969 resulted in partial (68%) pentobarbital substitution. The ability to train the present three-choice discrimination in rats indicates that the discriminative stimulus effects of 10.0 mg/kg pentobarbital were separable from those of 2.0 g/kg ethanol. The results suggest that the pharmacological effects of ethanol, which can control behavior, may seemingly be modified by training conditions (two-versus three-choice discrimination procedures), to the extent that a receptor system prominently linked to the behavioral activity of ethanol (i.e. GABAA) appears no longer to be involved in the interoceptive effects of the drug.     

Enhancement of dibenzothiophene biodesulfurization using β-cyclodextrins in oil-to-water media

It has been reported that biodesulfurization (BDS) of dibenzothiophene (DBT) in oil-to-water emulsions is carried out by growing cells of the aerobic Rhodococcus erythropolis IGTS8 strain and developing the so-called 4S desulfurization pathway. On adding β-cyclodextrins, it is possible to improve the BDS yields, increase the diffusion of DBT into the aqueous phase or avoid the HBP accumulation. Moreover, by using greater biocatalyst initial concentrations and adding 15 ppm of β-cyclodextrin, a very high BDS yield has been observed, but the presence of mass transfer limitations and the inhibition effects were not satisfactorily avoided. The Haldane kinetic model agreed well with the experimental results obtained, and the values of the kinetic parameters were determined.     

Stability evaluation of an immobilized enzyme system for inulin hydrolysis

The stability of free and Amberlite-immobilized inulinase, aiming at inulin hydrolysis was evaluated. The apparent activation energy of the biotransformation decreased when the immobilized biocatalyst was used, suggesting diffusional limitations, despite a decrease in the optimal temperature for catalytic activity for the immobilized biocatalyst. Thermal deactivation, of both forms of the biocatalyst, was evaluated by the linear inverted model. Inulinase immobilization consistently enhanced half-life of the enzyme, which increased up to 6-fold, as compared to the free form. Mean enzymatic activity was computed for both forms of the biocatalyst, and evidenced a decrease of optimal temperature with increased incubation periods. The deactivation energies estimated by an Arrhenius plot, evidenced a decrease of roughly 20% when free inulinase was used. The immobilized biocatalyst was effectively reused in successive batch runs for the hydrolysis of a 5% inulin solution.     

Gas–liquid mass transfer in oil–water emulsions with an airlift bio-reactor

Biodesulfurization reaction must be performed in oil–water emulsions with an aerobic biocatalyst which demands oxygen. Different reactor configurations can be used for this purpose, but the bubble column bio-reactors with internal recirculation loop are usually not used. In the present work, the absorption of oxygen in water–dodecane emulsions was studied in a bubble column bio-reactor with internal recirculation loop, in operative conditions normally used for biodesulfurization. The K_La for oxygen was determined for several organic fractions from 0 to 100%, as well as at different gas flow rates. Estimation of K_La was done according to a fluid dynamic model based on an energy balance which takes into account the energy dissipated at the interfaces and on a mass transfer model based on the fluid dynamic model, the Higbie's penetration theory and Kolmogoroff's theory of isotropic turbulence. Experimental data of mass transfer coefficient were simulated with satisfactory accuracy, and differences were less than 20% for most cases. Mayor deviations were obtained for emulsions with 30 and 70% dodecane fraction. To obtain good agreement, assumptions of higher bubble diameter and slip velocity were done, evincing the effect of surface tension and liquid viscosity on the mass transfer coefficient.