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The study of ceramic materials has attracted the attention of many researchers due to the possibility of their use in nanotechnology. The spinel ferrites form a large group of materials with a broad range of applications. Some examples include electronic devices such as high-frequency transformer cores, antenna rods, induction-tuners, among many others. However, when the ferritic materials display superparamagnetic behavior, their potential for biological applications like drug delivery, hyperthermia, resonance magnetic imaging and magnetic separation, become amazingly high. Therefore, the superparamagnetism is a characteristic strongly desired for spinel ferrites. Since this phenomenon is size-dependent, the methodologies to synthesize these materials has emerged as a crucial step in order to obtain the desired properties. In this regarding, several synthetic processes have been developed. For example, co-precipitation is a fast and cheap method to synthesize superparamagnetic spinel ferrites. However, methodologies involving microwave, ultrasound or polymers frequently result in these kind of materials. Therefore, this review brings a brief historic introduction about spinel ferrites as well as essential concepts to understand their structure and magnetic properties. In addition to this, recent advances in synthesis and applications of the superparamagnetic spinel ferrites are mentioned. Contents of Paper

Prolonged exposure to ultraviolet (UV) radiation from the sun can result in several skin problems, such as accelerating aging, burns, blemishes, or even cancer. Even when wearing clothes, there is still a risk that the user will be exposed to UV radiation and suffer skin damage. Therefore, it is necessary to apply anti-UV treatments to the clothes and fabrics used, so that users become safe. Nitrogen doped graphene quantum dots (N-GQD) and titanium dioxide (TiO2) NPs are materials that have a broad spectrum of UV absorption and are promising candidates to be applied in functional finishing in use on textile materials, giving textiles property anti-UV. The aim of this research is to evaluate the synergy effect between N-GQD and TiO2NPs in getting a nanocoating that can be applied on a cotton fabric, add photoluminescent and anti-UV properties. The nanocoatings obtained were applied via industrial discontinuous method, the high-pressure and high-temperature exhaustion process to the cotton fabric using polyvinyl alcohol as a binding agent. According to the UV protection assessment, it was observed that both materials are excellent UV absorbers and their ultraviolet protection factor (UPF) ​​are highly dependent on the concentrations used in the nanocoated cotton fabrics. Thus, nanocoated cotton with TiO2, N-GQD and TiO2/N-GQD revealed an UPF of +50, which established their effectiveness in protecting against UV radiation. They also withstand up to 20 wash cycles with no change in UPF.

Due to a fast progress in the development of communication systems, the dielectric and magnetic ceramics (ferrites) have become attractive to be used in devices. Although the ferrites of the spinel type were the first material to be used in the microwave range, garnets have smaller dielectric losses and, therefore, are chosen for many applications. High demands for modern electric applications in magnetic materials results in new techniques and products being permanently studied and researched, with a consequent appearance of new solutions for a wide applications series. This work presents the study of the ferrimagnetic composite, constituted by Y3Fe5O12 (YIG) and Gd3Fe5O12 (GdIG) phases, through solid state synthetic route and submitted to high-energy mechanical milling. Additionally, experiments were made in order to evaluate the electric and magnetic behavior of the composites at radio frequency and microwave range and then later suggest an adequate technological application. The composites were efficient as ferrite resonator antennas (FRAs) and microstrip antennas (thick films deposited on metalized surface alumina substrate by screen-printing technique), in the microwave frequency range. The experiments with FRAs showed satisfactory results due to the control of the antennas radiation characteristics and their tuning by the use of an external magnetic field. The composite resonators studied in this work can be important to the development of a third generation (3G) wideband antennas to cell phones and other wireless products.