The Cobalt Oxide-Based Composite Nanomaterial Synthesis and Its Biomedical and Engineering Applications

The magnetic nanoparticles (NPs) are offering a wide range of applications in medical and engineering fields. Among all the magnetic nanoparticles, cobalt oxide (Co3O4) nanoparticles and its composite-based nanoparticles are attracting more interest from researchers because of its unique mechanical, thermal, and magnetic properties. The aim of this book is to bring together a number of recent contributions regarding the cobalt oxide-based composite nanoparticles from several researchers all over the world. The latest research results, innovations, and methodologies are reported in the book in order to support the discussion and to circulate ideas and knowledge about the applications of these materials in medical and engineering applications. This chapter presents the methodology for the synthesis and characterization and applications of cobalt oxide-based composite nanoparticles. The detailed analysis related to toxicity of these nanocomposite materials is also included in this book chapter

Combination of Co3O4 deposited rGO hybrid nanofluids and longitudinal strip inserts: thermal properties, heat transfer, friction factor, and thermal performance evaluations

The reduced-graphene oxide/cobalt oxide hybrid nanoparticles were prepared based on the in-situ/chemical co-precipitation technique, and they were analyzed by transmission electron microscope, x-ray diffraction, and magnetometer techniques. The hybrid nanofluids were prepared with particle loadings of 0.05%, 0.1%, and 0.2% by dispersing synthesized reduced-graphene oxide/cobalt oxide in distilled water and their physical properties were measured. The thermal performance of the nanofluids was studied, when they flow in the turbulent regime through a circular tube. The thermal performance was also evaluated when straight (longitudinal) strip inserts with aspect ratios of 1, 2, and 4, were used inside the circular. These straight strip inserts by increasing the flow turbulence intensity act as turbulators. Results indicate that with a dilution of 0.2% concentration of hybrid nanoparticles in water, the Nusselt number is enhanced by 25.65%, and it is further enhanced by 110.56% with a straight strip insert of aspect ratio 1. The use of hybrid nanofluids and straight strip inserts leads to a slight penalty in fluid friction. For 0.2% concentration of hybrid nanoparticles in water, the penalty in friction factor is 11%, and it is further increased to 69.8% with 0.2% particle loadings and a straight strip insert of aspect ratio1. Moreover, the thermal performance factor of hybrid nanofluids with and without straight strip inserts presents values higher than 1, which shows the benefit of the prepared hybrid nanofluids in a turbulent flow. A general form of regression equations are developed based on the experimental data.publishe

Efficiency, energy and economic analysis of twisted tape inserts in a thermosyphon solar flat plate collector with Cu nanofluids

Heat transfer, friction factor and efficiency of a thermosyphon type flat plate collector with and without twisted tape inserts were analyzed experimentally. Water based Cu nanofluids were used as the absorber fluid to receive the heat from solar radiation into the flat plate collector. The experiments were conducted for volume concentrations of 0.1% and 0.3% and twist ratios of H/D = 5, 10 and 15. Results reveal that the heat transfer rate and efficiency of nanofluids increase with the increase of particle volume concentrations. The Nusselt number of 0.3% nanofluid is enhanced up to 20.46%, and it is further enhanced up to 46.90% with twisted tape insert of H/D = 5 with a maximum friction factor penalty of 1.477-times compared to plain collector. The efficiency of the solar collector with water is 52% and it is enhanced to 58% for 0.3% nanofluid, whereas it is further enhanced to 64% for 0.3% nanofluid with twisted tape insert of H/D = 5. Empirical correlations are proposed based on the experimental data for the friction factor and Nusselt number with a standard deviation of less than ±6.5%. The study indicates that for 100 units of solar flat plate collector the use of 0.1% and 0.3% Cu nanofluids leads to weight savings of 284 kg and 567 kg, respectively. The total weight of 100 units of solar flat plate collector is further saved by 767 kg, 1050 kg and 1250 kg for 0.3% nanofluid with twisted tape inserts of H/D = 15, H/D = 10 and H/D = 5, respectively. The collector cost is reduced by 5.66% and 11.33% for 0.1% and 0.3% nanofluids, and it is further reduced to 25% for 0.3% nanofluid with a twisted tape insert of H/D = 5.publishe

Chemical and physicochemical changes in Serrana goat cheese submitted to extra-long ripening periods

Goat milk cheese is highly appreciated since ancient times. However, besides being consumed close to its production date, according to the common practice, there is an increasing trend towards consuming goat milk cheese submitted to long ripening periods. Throughout this process, several chemical changes are expected, justifying the different properties presented by ripe cheese in comparison to fresh one. Accordingly, proximate composition, salt percentage, saponifiable matter, color parameters, pH and fatty acids were compared in cheese submitted to medium, long and extra-long ripening. The parameters showing significant changes among different ripening periods were effectively identified, highlighting fatty acids as the ones with highest variation. Actually, fatty acids profiles were successfully assayed as a chemical fingerprint of goat milk cheese submitted to different ripening periods. This result raised up the possibility of discriminating goat milk cheese ripening period using a single, fast and reliable chromatographic methodology.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) and FEDER under Program PT2020 for financial support to CIMO (UID/AGR/00690/2013) and A. Fernandes (SFRH/BPD/114753/2016) grant. The authors are also grateful to the project funded by the Proder program - Measure 4.1 - Cooperation for Innovation - PA 49 481 - in partnership with LEICRAS.info:eu-repo/semantics/publishedVersio

Targeting excessive free radicals with peels and juices of citrus fruits: grapefruit, lemon, lime and orange

A comparative study between the antioxidant properties of peel (flavedo and albedo) and juice of some commercially grown citrus fruit (Rutaceae), grapefruit (Citrus paradisi), lemon (Citrus limon), lime (Citrus aurantiifolia) and sweet orange (Citrus sinensis) was performed. Different in vitro assays were applied to the volatile and polar fractions of peels and to crude and polar fraction of juices: 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity, reducing power and inhibition of lipid peroxidation using b-carotene–linoleate model system in liposomes and thiobarbituric acid reactive substances (TBARS) assay in brain homogenates. Reducing sugars and phenolics were the main antioxidant compounds found in all the extracts. Peels polar fractions revealed the highest contents in phenolics, flavonoids, ascorbic acid, carotenoids and reducing sugars, which certainly contribute to the highest antioxidant potential found in these fractions. Peels volatile fractions were clearly separated using discriminant analysis, which is in agreement with their lowest antioxidant potential

Portuguese wild mushrooms at the "Pharma-Nutrition" interface: nutritional characterization and antioxidant properties

The search for foods that might improve health or reduce disease risk, has been progressively gaining interest. Mushroom could be examples of these foods, presenting the additional advantage of being recognized as a delicacy. This feature might place mushrooms in the pharma-nutrition interface. Herein, eight different mushroom species were characterized in terms of nutrients (proteins, carbohydrates, fat, individual sugars, fatty acids) and bioactive compounds (tocopherols, carotenoids, organic acids and phenolic compounds) with recognized antioxidant properties. These medicinal properties are often related with the antioxidant potential presented by mushroom extracts. Boletus regius was the species with the highest levels of carbohydrates (88.79 g/ 100 g dw) and PUFA (56.55%), bioactive compounds such as tocopherols (763.80 µg/100 g dw), citric acid (3.32 g/ 100 g dw) and phenolic compounds (23.49 mg/ 100 g dw), including two chrysin derivatives, presenting also the highest antioxidant activity. The identified bioactive compounds might be used as nutraceuticals to prevent chronic diseases related with oxidative stress. Furthermore, all tested species are edible, and could be incorporated directly in diet acting as functional foods.Fundação para a Ciência e a Tecnologia (FCT, Portugal) and COMPETE/QREN/EU for financial support to this work (research project PTDC/AGR-ALI/110062/2009) and to CIMO (strategic project PEst-OE/AGR/UI0690/2011). L. Barros and J.C.M. Barreira also thank to FCT, POPH-QREN and FSE for their grants (SFRH/BPD/4609/2008 and SFRH/BPD/72802/2010, respectively)

Technical and economic pre-feasibility study for the construction of septic tank-filter-sinkhole with alternative material

Received: February 2nd, 2021 ; Accepted: August 3rd, 2021 ; Published: August 24th, 2021 ; Correspondence: [email protected] study of the different materials used in the construction of septic tanks aims to facilitate and spread the use of this sewage treatment system in places that are not assisted by municipal sewage systems and in the rural area, which despite having a smaller number of inhabitants compared to the urban area This study aims to carry out a technical and economic evaluation of the concrete and tires using in the construction of septic tanks-filter-sinkhole. The wastewater treatment systems were built according to the recommendations in NBR 7229/93 and 13969/97. To evaluate the efficiency of each system built, the following parameters were analyzed: chemical oxygen demand (COD), the potential of hydrogen (pH), alkalinity, acidity, and temperature. In the economic evaluation, the materials and labor required to install the systems were considered using the Brazilian cost database (SINAPI), and an economic and financial feasibility study was carried out. According to the technical and economic analysis of construction, both systems showed the same technical performance, however, the concrete design proved to be more advantageous than the tire design, considering the difficulty in acquiring the tires and the high cost if it is necessary to buy them, in addition to the greater difficulty in handling and installing the tire system compared to the concrete one

Bibliometric analysis on the use of natural fibers in construction materials

Received: February 2nd, 2021 ; Accepted: August 3rd, 2021 ; Published: August 30th, 2021 ; Correspondence: [email protected] to the increasing interest of the population in the sustainability theme, there was a consequent growth in publications related to the theme in the area of civil construction. Agroindustrial waste has become an environmental problem, and with that natural fibers have found space in the reuse of waste due to its characteristics and possibilities of improving the mechanical properties of its products. In order to achieve sustainable construction demand, along with the need to reuse waste, studies have begun to analyze the application of natural fibers in construction materials. The documents provided by the Web of Science (WOS) database through research carried out with the search for the terms ‘Natural Fibers’ and ‘Building materials’ restricted to the period 2010–2020 in the main WOS collection. The institutions involved with the publications, the countries of origin of the documents, the year of publication, the keywords used by the authors and the number of citations for each document were analyzed using bibliometrics in the VOSVIEWER (VOS) software. The result of the analysis shows an increase in documents related to the theme over the years, and that the countries with the most studies in the area are China (16), USA (14) and Brazil (11), respectively. The results presented after analysis of the keywords show that natural fiber (61 occurrences), mechanical properties (44 occurrences) and composites (31 occurrences) are the words with the highest occurrence among the analyzed documents. The present study shows the growth of research related to the theme, in addition to discriminating countries, institutions and authors, which allows monitoring the scientific expansion of the theme and guiding future studies