Agradecimentos: This work was supported by the Coordination for the Improvement of Higher Education Personnel (CAPES) for the scholarships to K.C.F. Toledo. The authors would like to thank the Brazilian Council for Scientific and Technological Development (CNPq), Fundação Araucária/Paraná and National Center of High Performance Computing in São Paulo (CENAPAD Project 557/2013)

Agradecimentos: The authors acknowledge the financial support by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001, Fundo de Apoio ao Ensino, à Pesquisa e Extensão, Universidade Estadual de Campinas, FAEPEX-UNICAMP (grant#2824/17), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq – grant#459923/2014-5) and Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP - grant#2013/22127-2)

In this study, biogenic SiO2 of high purity and high surface area obtained from rice husk was used for prepare a nanostructured SnO2/SiO2composite. The predominantly amorphous silica was extracted in an acidic route and then the nanocomposite was done via sol-gel route using ethylene glycol and citric acid followed by heat treatment. SiO2 content of the rice husk was determined by X-ray fluorescence (XRF) and its specific surface area determined by nitrogen adsorption. The composite nanostructured SnO2/SiO2 was structurally characterized by the techniques of X-ray diffraction (XRD), Raman and Fourier transform infrared (FT-IR) spectroscopy. The morphological characteristics were revealed by scanning electron microscope (SEM).

In this paper, a low-cost and versatile lab-made photoreactor was constructed for the preparation of nanomaterials such as gold nanoparticles and reduced graphene oxide. The power of the lab-made photoreactor can be easily adjusted according to the number of lamps turned on. Moreover, the lab-made photoreactor allows the utilization of different sources of irradiation with distinct wavelengths. Performance tests for production of gold nanoparticles showed reproducibility and equal efficiency as compared to the literature. Also, the photoreactor powered with UV-A and UV-C as sources of irradiation can be used for modulation of the reduction degree of graphene oxide.

Agradecimentos: This research was supported by Fundac¸ ão de Amparo à Pesquisa do Estado de São Paulo (FAPESP, 2010/17804-7), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) and the National Institute of Science, Technology and Innovation in Complex Functional Materials (Inomat/INCT, FAPESP 2008/57867-8, CNPq 573644/2008-0). P.F. Andrade also thanks CAPES for the scholarship. The authors gratefully acknowledge the assistance of Professor Miguel Jafelicci Junior ' in the first steps of this work and also R.J. Poppi and M.B.M. Lopez (Institute of Chemistry/UNICAMP) in obtaining the Raman spectra

The present paper describes a new way to construct composite electrodes by using beeswax as an alternative binder and graphite powder as the conductive phase. Beeswax can be an attractive binder since it is a biodegradable and renewable material. Also, it attributes to the composite material a good rigidity after dry at room temperature. The monitoring of hydrogen peroxide (H2O2) in honey is extremely important due to its antibacterial properties, which are vital for the maintenance of the hive. The determination of H2O2 by electrochemical techniques is widely noted in the literature, mainly using redox mediators or catalysts, such as Prussian blue (PB). Therefore, the proposed composite electrode was prepared with beeswax and graphite in n-hexane, and the PB was electrochemically synthesized by cyclic voltammetry. The constructed electrode showed a low resistance of electronic transfer (60 Ω), high electroactive surface area, and high electronic transference constant (1.73×10−3 cm s−1) when compared with other composite electrodes. The presence of PB on composite electrode allowed the amperometric determination of H2O2 with good linearity (R2 = 0.997) at a concentration range of 1.0−180 µmol L−1 H2O2, showing a sensitivity of 0.184 µAL µmol−1. Consequently, it was possible to determine H2O2 accurately at three concentration levels in wild honey samples (RSD = 98.5−102%), suggesting the use of this alternative method for the quality control analysis of honey.

Agradecimentos: The authors are grateful and acknowledge the financial support by CNPq (grant# 459923/2014-5), Fundo de Apoio ao Ensino, à Pesquisa e à Extensão – Universidade Estadual de Campinas, FAEPEX-UNICAMP (grant# 2824/17 and grant# 2145/18), and Fundação de Amparo à Pesquisa do Estado de São Paulo, FAPESP (grant# 2013/22127-2, grant# 2017/23960-0 and grant# 2018/03576-4). This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES) – Finance Code 001. We also acknowledge Prof. Dr José Ramón Galán Mascarós and Dr Marta Blasco-Ahicart from Instiut Català d'Investigaciò Científica (ICIQ)

Agradecimentos: The authors are grateful and acknowledge the financial support of Brazilian Funding Agencies. This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001, Conselho Nacional de Desenvolvimento Científico e Tecnológico CNPq (grant# 427731/2018-6 and grant# 307271/2017-0), and Fundação de Amparo à Pesquisa do Estado de São Paulo, FAPESP (grant#2013/22127-2 and grant#2017/23960-0). The authors thank the LNNano for technical support during scanning Kelvin probe force microscopy work