Chelating resins for mercury extraction based on grafting of polyacrylamide chains onto styrene–divinylbenzene copolymers by gamma irradiation

Chelating resins for mercury adsorption were prepared by grafting polyacrylamide chains onto styrene–divinylbenzene (Sty–DVB) copolymers by applying gamma radiation. Sty–DVB copolymers were synthesized by aqueous suspension polymerization employing different synthesis conditions. The copolymers were characterized by apparent density, surface area, pore size distribution and swelling capacity. The copolymers were irradiated using a ⁶⁰Co-γ source at room temperature in the presence of acrylamide solution in methanol. The grafting reaction was evaluated with the aid of elemental analysis, FTIR and thermogravimetric analysis (TGA). Hg(II) uptake measurements were carried out in batch experiments. The results showed that these resins can be successfully used for Hg(II) adsorption at ppm levels. The porosity degree of the copolymers influences the grafting yield as well as the Hg(II) complexation capacity of the chelating resins.     

Modeling of continuous thermal processing of a non-Newtonian liquid food under diffusive laminar flow in a tubular system

The classic conservative approach for thermal process design can lead to over-processing, especially for laminar flow, when a significant distribution of temperature and of residence time occurs. In order to optimize quality retention, a more comprehensive model is required. A model comprising differential equations for mass and heat transfer is proposed for the simulation of the continuous thermal processing of a non-Newtonian food in a tubular system. The model takes into account the contribution from heating and cooling sections, the heat exchange with the ambient air and effective diffusion associated with non-ideal laminar flow. The study case of soursop juice processing was used to test the model. Various simulations were performed to evaluate the effect of the model assumptions. An expressive difference in the predicted lethality was observed between the classic approach and the proposed model. The main advantage of the model is its flexibility to represent different aspects with a small computational time, making it suitable for process evaluation and design.     

Lithium conducting solid electrolyte Li1.3Al0.3Ti1.7(PO4)3 obtained via solution chemistry

NaSICON-type lithium conductor Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP) is synthesized with controlled grain size and composition using solution chemistry. After thermal treatment at 850 °C, sub-micronic crystallized powders with high purity are obtained. They are converted into ceramic through Spark Plasma Sintering at 850–1000 °C. By varying the processing parameters, pellet with conductivities up to 1.6 × 10^?4 S/cm with density of 97% of the theoretical density have been obtained. XRD, FEG-SEM, ac-impedance and Vickers indentation were used to characterize the products. The influence of sintering parameters on pellet composition, microstructure and conductivity is discussed in addition to the analysis of the mechanical behavior of the grains interfaces.     

Nondestructive evaluation of timber: the new Brazilian code for the design of timber structures

The grading of structural timber members allows for their greater efficiency and quality. This grading can be done by means of nondestructive methods that improve the evaluation process. Timber grading makes it possible to augment the k _mod,3 coefficient, resulting in greater structural reliability. The purpose of this work was to calibrate the modification coefficient (k _mod,3) of the Brazilian NBR 7190:2007 code for the Design of Timber Structures. The modification coefficients are numbers that govern the estimation of a property of a material as a function of phenomena that may occur permanently or during a certain period of the service life of the building, being that the coefficient k _mod,3 leads in consideration if the wood is of first or second-class quality. The experimental procedure involved a study of structural members of Eucalyptus grandis and Pinus sp., which were graded by ultrasound and transverse vibration techniques to determine the dynamic modulus of elasticity (E_d). The members were visually graded and static bending tests (MOE) were conducted concomitantly. The results indicated that the transverse vibration technique yielded higher modification coefficient (k _mod,3) values than the ultrasound technique, since it grades the material at values closer to those obtained in static bending.     

RTD studies in a falling film graphite evaporator with internal spiral fins: Influence of the geometry

A hydrodynamic study of a new graphite evaporator has been performed. In this exchanger the fluid flows as a thin film on a spirally wound fin which forms a spiral staircase inside a tube. The slope θ_m of the spirally wound fin is modifiable. The residence time distribution (RTD) of the film was measured for different fin slopes θ_m and several film flowrates m_f. The flow pattern was then modelled thanks to the DTS software as a cascade of perfect mixed cells and the mean residence time τ_m was calculated. The evolution of τ_m as a function of θ_m and m_f is accurately represented by a power law relation.     

Surface modification of styrene-divinylbenzene copolymers by polyacrylamide grafting via gamma irradiation

Polyacrylamide chains were grafted onto styrene-divinylbenzene (S-DVB) copolymer beads using gamma radiation from a ⁶⁰Co source by applying the simultaneous method. S-DVB macroporous copolymer was synthesized by aqueous suspension polymerization and characterized by determining apparent density, surface area, pore volume distribution and water uptake. Optical and electron microscopies were used in order to observe the copolymer morphology. The effect of parameters such as monomers concentration, irradiation dose and presence of inhibitor (Mohr’s salt) on grafting reaction was studied. The grafting reaction was evaluated with the aid of elemental analysis, FTIR, HR-MAS NMR spectrometry, thermogravimetry (TG) and electron microscopy. Grafting yield (evaluated by nitrogen content) increased with acrylamide concentration and irradiation dose increasing. However, above determined values of those parameters it is observed a tendency of decreasing on the grafting yield. The presence of Mohr’s salt inhibited the production of homopolymer as well as the progress of the grafting reaction.     

Chlorogenic acids and related compounds in medicinal plants and infusions

The consumption of plant infusions for prevention and treatment of health disorders is a worldwide practise. Various pharmacological activities inherent to medicinal plants have been attributed to their phenolic composition, including chlorogenic acids (CGA). Studies have shown potential beneficial properties of CGA to humans such as antioxidant, hepatoprotective, hypoglycaemic. In the present study, the CGA composition of 14 dried medicinal plants was determined by HPLC-UV and LC-DAD–ESI-MS. The plants with the highest CGA contents were Ilex paraguariensis, Bacharis genistelloides, Pimpinella anisum, Achyrochine satureioides, Camellia sinensis, Melissa officinalis and Cymbopogon citratus, with 84.7 mg/100 g–9.7 g/100 g, dry weight. Plant infusions were prepared (at 0.5%) in order to evaluate the actual consumption of CGA through these beverages. Total CGA contents in the infusions were similar to those in the methanolic extracts and indicated that a satisfactory extraction occurs during the preparation of infusions. These CGA-rich plants deserve attention regarding the pharmacological properties attributed to CGA.     

Influence de la dose de neutrons rapides sur la formation des cavites dans l'aluminium

The results of neutron irradiation of aluminium at 55°C under a fast flux of $\text{(1.4 ± 0.2) 10}{}^{14}\text{n · cm}{}^{\mathrm{?2}}\text{· sec}{}^{\mathrm{?1}}$ to doses ranging between 10¹⁹ and $\text{3 × 10}{}^{21}\text{n · cm}{}^{\mathrm{?2}}$ are presented. Experimental observations suggest that dislocations play an important role in void nucleation and growth. Monte-Carlo calculations of void growth in the presence of a dislocation describe reasonably well the experimental results.     

Natural antimicrobial ingredients incorporated in biodegradable films based on cassava starch

Biodegradable films based on cassava starch and with addition of natural antimicrobial ingredients were prepared using the casting technique. The tensile properties tensile strength (TS) [MPa] and percent elongation (E) at break [%] and the water vapor transmission (WVT) of the biodegradable films were evaluated and compared with the control (without antimicrobial ingredients). The evaluation of the Colony Forming Units per gram [CFU/g] of pan bread slices packed with the best biodegradable films, in terms of packaging performance, was also determined. The addition onto the matrix of only clove and cinnamon powders could reduce the films WVT when compared to the control, however TS and E were lower than the control and the effect of cinnamon was milder regarding this property. Since water activity of the pan bread slices packed with the biodegradable films increased considerably during the storage period, the antimicrobial effect could not be clearly determined.     

Furan and Methylfurans in Foods: An Update on Occurrence,Mitigation, and Risk Assessment

The acceptance of many foods is related to traditional cooking practices, which create taste and texture and are important to digestibility, preservation, and the reduction of foodborne illnesses. A wide range of compounds are formed during the cooking of foods, a number of these have been shown to lead to adverse effects in classical toxicological models and are known as food processing contaminants (FPC). It is essential that the presence and effects of such compounds alone and in combination within the diet are understood such that proportionate risk management measures can be developed, while taking a holistic view across the whole value chain. Furan and alkylfurans (principally 2‐ and 3‐methylfuran) are highly volatile FPC, which are formed in a wide range of foods at low amounts. The focus of research to‐date has been on those foods, which have been identified to be most consequential in terms of being sources of exposure, namely jarred and canned foods for infants and young children (meals and drinks) and coffee (roast and ground, soluble). This report presents (i) new industry data on the occurrence of furan and methylfurans in selected food categories following previous coffee studies, (ii) the most salient parameters that impact furan formation, and (iii) aspects of importance for the risk assessment.