Exotic fruits as a source of important phytochemicals: Improving the traditional use of Rosa canina fruits in Portugal

Several exotic fruits are used in folk medicine as potential sources of healthy compounds. Rosa canina L. (dog rose) fruits and other parts used to be widely consumed in rural areas from Portugal. The present work intends to highlight the presence of bioactive compounds in those different parts, in order to improve their use based on scientific studies. The antioxidant activity was screened through: radical scavenging effects, reducing power, and inhibition of lipid peroxidation in brain homogenates. Phytochemical characterization included determination of sugars by HPLC-RI, fatty acids by GC-FID, tocopherols by HPLC-fluorescence, phenolics, flavonoids, carotenoids, chlorophylls and ascorbic acid, by spectrophotometric techniques. Galls revealed the highest antioxidant potential, ripen hips showed the highest tocopherols and ??-carotene contents, as also the most adequate n-6/n-3 fatty acids ratios. Unripe hips gave the highest levels of ascorbic acid and petals revealed the highest concentration of sugars. Ethnobotanical studies conducted have mentioned different use-reports for seeds, petals, flowers and galls, as well as for fruits in different stages of maturity and, therefore, the comparison between chemical compounds and antioxidant properties of those different parts is a key-point of the present study. Furthermore, the levels of antioxidants found would make them suitable sources of compounds to be used commercially to retard rancidity in fatty materials in food manufacturing, to reduce the effects of ageing and to help to prevent oxidative-stress related diseases such as cancer and heart disease.     

Magnesium oxide synthesized with Alpinia zerumbet leaf extracts as a sustainable alternative to zinc oxide in nitrile rubber compounds: A comparative vulcanization kinetics investigation

Zinc oxide (ZnO) is the most widely used activator in the rubber industry; however, there is growing concern about its use as it can become toxic to the environment, particularly in aquatic systems. This study describes the synthesis of magnesium oxide (MgO) assisted by the Alpinia zerumbet extract, which is then used as an activator in the replacement of ZnO to vulcanize nitrile rubber (NBR) containing 33% and 45% acrylonitrile (ACN). The t₉₀ for NBR-33% and NBR-45% are 20 and 15 min, respectively. This indicates a reduction of 5 min in t₉₀ with an increase in ACN. In comparison, ZnO-activated NBR compounds exhibit the opposite trend, with t₉₀ increasing from 10 for NBR-33% to 19 min for NBR-45%. Furthermore, the decrease in activation energy (E_a) with the increase in conversion for 33%-MgO and 45%-MgO indicates that vulcanization with MgO is a complex process. This behavior is comparable to that of 45%-ZnO, but not for 33%-ZnO because its E_a remains oscillating at 80–90 kJ mol⁻¹ in the entire conversion range. The crosslink densities of 33%-MgO and 45%-MgO are 5.87 and 4.78 mol cm⁻³, respectively. These values are slightly higher than those for 33%-ZnO (5.77 mol cm⁻³) and 45%-ZnO (4.38 mol cm⁻³).     

Biolubricant Production from Stearic Acid and Residual Secondary Alcohols: System and Reaction Design for Lipase-Catalyzed Batch and Continuous Processes

Catalysis Letters - Six lipases were immobilized on a styrene–divinylbenzene support and evaluated on the batch esterification reaction of stearic acid with fusel oil. After a screening...     

Mapping the literature on credit unions: a bibliometric investigation grounded in Scopus and Web of Science

Scientometrics - Credit unions play a relevant role in providing microcredit and other financial services. Because such financial cooperative organizations have drawn the attention of a significant...     

The effect of the geometrical optical phase on the propagation of Hermite-Gaussian beams through transversal and parallel dielectric blocks

When an optical beam propagates through dielectric blocks, its optical phase is responsible for the path of the beam. In particular, the first order Taylor expansion of the geometrical part reproduces the path predicted by the Snell and reflection laws whereas the first order expansion of the Fresnel phase leads to the Goos-Hänchen shift. In this paper, we analyze the effects of the second order Taylor expansion of the geometrical phase on the shape of the optical beam and show how it affects the transversal symmetry of Hermite-Gaussian beams. From the analytical expression of the transmitted beam, it is possible to determine in which transversal and parallel dielectric blocks configuration the transversal symmetry breaking is maximized or when the symmetry is recovered. We also discuss the axial spreading delay.     

Prediction of the neutrons subcritical multiplication using the diffusion hybrid equation with external neutron sources

We used the neutron diffusion hybrid equation, in cartesian geometry with external neutron sources to predict the subcritical multiplication of neutrons in a pressurized water reactor, using a 1/M curve to predict the criticality condition. A Coarse Mesh Finite Difference Method was developed for the adjoint flux calculation and to obtain the reactivity values of the reactor. The results obtained were compared with benchmark values in order to validate the methodology presented in this paper.     

Structural and magnetic behavior of zirconia-magnetic particles and zirconia-graphene composite ceramics

Incorporating magnetic materials in ceramic matrices becomes an attractive topic due to its versatility and wide range of applications. Therefore, this work aims to produce zirconia-magnetic particles and zirconia-graphene composites, investigating their structural and magnetic properties. The ceramic composites were produced by the tape casting technique and characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and magnetic measurements. The microstructural characterization showed monoclinic and tetragonal zirconia phases from the zirconia powder and the magnetite and hematite phases from the magnetic particles. Three peaks of characteristics known as band D, G, and 2D evidenced the presence of graphene. The morphology of the zirconia-magnetic particles and zirconia-graphene composites showed grains with irregular shapes and varying sizes; however, the zirconia-graphene composite showed the presence of pores and agglomerates due to the plasma heat-treatment process. The uniform dispersion of the elements in both ceramic composites confirmed the efficiency of the applied method. The magnetic characterizations of the green and sintered zirconia-magnetic particles and zirconia-graphene composites were studied in a wide range of magnetic fields and temperatures (5 to 300 K). Before sintering, the magnetite phase commanded the magnetic response of the zirconia-magnetic particles composite, showing a ferrimagnetic behavior, after sintering, the hematite phase content increased by approximately 27%, causing a change in the ferrimagnetic order to antiferromagnetic. It was found that the 1% graphene insertion in the zirconia ceramic composite was responsible for the ferromagnetic behavior of the sintered composite. Ceramic composites become future candidates for technological applications in spintronic devices and magnetic storage.     

Cmc of PMMA-<Emphasis Type="Italic">block</Emphasis>-PDMAEMA measured by NPN fluorescence

Relationships able to predict the behavior of polymers based on their chemical structure are necessary for the rational synthesis of materials with desired properties. The state-of-art of polymer chemistry allows one to synthesize, using techniques such as RAFT, polymers with tailored chemical structures to study that kind of relationships. In this study, RAFT was used to synthesize copolymers—poly(methyl methacrylate)-block-poly[(2-dimethylamino)ethyl methacrylate]—that form aggregates in water at neutral and acidic pH’s. Cmc of each copolymer was determined by fluorescence using the probe N-phenyl-1-naphthylamine (NPN), and the values are consistent with the particular chemical structure of each one. These findings can be useful in future studies of dependence of cmc on the chemical structure and solution conditions and to tailor polymers with specific properties and applications, making the cmc determination faster and more accurate. To the best of our knowledge, this it the first time that NPN is used to determine the cmc of this kind of positively charged copolymers.     

Biodegradation of mulch films from poly(butylene adipate co-terephthalate), carnauba wax,and sugarcane residue

Plastic mulching for agricultural purposes is a technique which began in the last century and since then its use has been perfected. The fragments of some large-scale mulch films used may accumulate in the soil, release toxic substances, and affect soil microbial activity. The environmental problems generated by fragments of plastic films accumulated in soil have prompted the development and large-scale use of biodegradable plastic mulch films. The aim of this work is to develop biodegradable plastic mulch films from poly(butylene adipate co-terephthalate (PBAT), sugarcane residue, and carnauba wax and to evaluate its biodegradation when buried in soil. The films, obtained by flat extrusion, contained 2.5 and 5.0% sugarcane residue and 0 and 2.0% carnauba wax. Their biodegradation after burial in soil was monitored by mass loss, visual inspection, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Our data show biodegradation in soil to increase with sugarcane residue content and to be independent on carnauba wax addition. This behavior, confirmed by visual inspection, FTIR and SEM images, was associated with the biodegradability of lignocellulosic residues as microorganisms tend to attack this component first, thus eroding fiber/matrix interface and facilitating bio disintegration. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48240.