This work aims to compare the construction of magnification devices. Details of the construction and use of microscopes based on webcam and smartphone are presented, using software for image processing. It is also presented the construction of microscopes using drops of different liquids as magnifying lens, a compound microscope, and a water-drop projector. Magnified images obtained with each device are presented, and the different microscopes are compared. The results obtained from the use of these alternative instruments confirm that alternative microscopes are instruments of easy reproducibility, enabling the amplification of samples for a more detailed observation of the object of interest. devices processing lens microscope waterdrop water drop projector compared reproducibility interest

Renewable resources are alternatives to fossil fuels and pyrolysis is identified as a process for the generation of biofuel products. The lignocellulosic sorghum is a cereal produced in brazil and it presents several applications, such as the production of second-generation ethanol. The present work aimed to study the slow pyrolysis of lignocellulosic sorghum, the biomass was characterized by means of proximate, ultimate, composition and carbohydrate analyzes. Thermogravimetric analyzes were performed with heating rates between 5 and 25 K min-1 and with N2 atmosphere. The Friedman model allows obtaining the kinetic parameters of biomass decomposition and is widely used due to its simplicity and precision; however, since it is sensitive to experimental noise, an algorithm was developed for the calculation of kinetic parameters for the slow pyrolysis of this biomass, enabling an accurate analysis of the experimental data. The activation energy found by the proposed methodology was 122.65 ± 19.24 kJ mol-1, with determination coefficients above 0.97. The comparison between experimental and theoretical data presented deviation values of 0.934%, 3.408% and 1.101% for heating rates of 5, 10 and 15 K min-1, respectively, showing the accuracy for the determined kinetic parameters.

Thermal decomposition of coffee husks was investigated by thermogravimetric analyses. The proximate, ultimate and composition analyses were performed. Thermogravimetric tests were realized, the material was heated to 1173 K using five heating rates: 5, 10, 15, 20, 25 K min-1. The kinetic parameters were estimated using the methods of Kissinger-Akahira-Sunose and Friedman, the distributed activation energy model and the independent parallel reactions model. The isoconversional models of Kissinger-Akahira-Sunose and Friedman showed the dependence between determined values of activation energy and mass conversion, the activation energy values varied from 1437.39 to 199.22 kJ mol-1 for Kissinger-Akahira-Sunose and from 127.81 to 230.35 kJ mol-1 for Friedman model. The values of activation energy were determined for Miura-Maki method; varying from 137.39 to 199.22 kJ mol-1. The model of parallel and independent reactions showed the presence of six different reactions (with activation energy values varying from 42.0 to 214.2 kJ mol-1) occurring during coffee husks pyrolysis, indicating a complex reaction. Currently, works regarding the determination of kinetic parameters for coffee husks pyrolysis are not common. The present work is the first report using the model of parallel and independent reactions to estimate kinetic parameters for pyrolysis of coffee husks, a residue widely generated worldwide.

A celulose do bagaço de cana-de-açúcar foi usada para sintetizar acetato de celulose com diferentes graus de substituição, os quais foram caracterizados por ¹H-RMN através da relação entre as áreas dos picos dos átomos de hidrogênio presentes nos grupos acetato (-(C=O)OCH3) e os picos dos hidrogênios ligados aos átomos de carbono dos anéis glicosídicos. A supressão de alguns sinais foi feita para remover sinais de ressonância da água residual nos materiais e também para remover sinais de impurezas no triacetato de celulose. Um método de deconvolução para o cálculo computacional do grau de substituição foi proposto. Os graus de substituição das amostras de acetato de celulose foram 2,94 e 2,60, o que está de acordo com os resultados por determinação química através de uma titulação ácido base.

Cellulose from sugarcane bagasse was used for synthesizing cellulose acetate with different degrees of substitution, which were characterized by ¹H-NMR through the relationship between the peak areas of the hydrogen atoms of the acetate groups (-(C=O)OCH3) and the peaks of the hydrogen bonded to the carbon atoms of the glucosidic rings. Suppression of some signals was carried out in order to remove the residual water resonance in the materials and those related to impurities in cellulose triacetate as well. A deconvolution method for the computation of the degree of substitution of acetylation is proposed. The degrees of substitution for the cellulose samples were 2.94 and 2.60, in good agreement with those obtained by chemical determination through an acid-base titration.

In the present paper, the use of poly(styrene sulfonate) (PSS), produced from discarded polystyrene materials through heterogeneous and homogeneous processes, was investigated. The use of PSS for water treatment, using a kaolin suspension as wastewater model, reduced water turbidity for all the employed materials when compared to the blank analysis, without PSS. The most efficient polyelectrolyte was PSS cups obtained by homogeneous route. The same behavior was observed for real system. The homogeneous PSS cups showed a balance between a moderate molecular weight and high anionic character that improved flocks formation and water removal turbidity.