A brief review of the characteristics and properties of cubic boron nitride (cBN) is presented, including different processing methods. The influence of bonding substances, as well as other ceramic ...composites, is also discussed. Finally, it is highlighted the great practical importance of the cBN as a ceramic with elevated hardness in substitution for the diamond in cutting tools.
Low-cost lignocellulosic filters were made from soybean hulls (SH), sugarcane bagasse fibers (SBF), cellulose nanofibers (CNF), and Kraft-bleached pulp (BP) as renewable feedstocks and applied in Cu ...(II) and Cd (II) removal from aqueous medium. Filtration was performed with a vacuum pump; filtration times ranged from 3 to 1200 seconds. For the same filter, the best permeate flow was 13,333 L.h.m-2 for both cations. The best Cd (II) removal (77.2 %) was achieved within 7 seconds at a permeate flow of 5,714 L.h.m-2. The same filter was also the best at removing Cu (II) (46.5 %), which was achieved within 7 seconds at a permeate flow of 5,714 L.h.m-2, as well. This short time evidenced that a long contact time is not needed to achieve higher removal. The best filter was made of BP, CNF, and SH. The presence of SBF and SH increased the contact angle and decreased the solid free energy surface. By FTIR-ATR it was possible to verify with which groups present in the chemical structures of the filter components the Cd (II) and Cu (II) cations interacted best. These results demonstrate the potential use of lignocellulosic biomass for producing composites aimed at water decontamination.
RESUMO O presente estudo contempla a aplicação de nanopartículas magnéticas de ferrita de manganês MnFe2O4 (NPM) modificadas com poliestireno sulfonado (PSS) na adsorção de íons de Pb (II) para fins ...de tratamento de água contaminada. A funcionalização da nanopartícula com o polímero objetivou aumentar a capacidade de adsorção e incluir a utilização de material reciclável em função da importância ambiental. Os adsorventes foram caracterizados por espectroscopia no infravermelho por transformada de Fourier, espectroscopia de energia dispersiva por raio X, difração de raios X, microscopia eletrônica de varredura, microscopia de força atômica, análise elementar, análise termogravimétrica, ponto de carga zero, área superficial e porosidade. O PSS representou 14% da massa das nanopartículas magnéticas de MnFe2O4 funcionalizadas com o poliestireno sulfonado (NPM-PSS) e o teor de grupos sulfônicos foi de 17,18%. Os modelos de isoterma de Freundlich e cinético de pseudossegunda ordem apresentaram maior acurácia pelos dados experimentais de adsorção dos íons Pb (II) pela NPM-PSS, cuja capacidade de adsorção das nanopartículas variou de 6,254 a 7,535 mg g−1.
ABSTRACT The present study contemplates the application of magnetic nanoparticles of manganese ferrite MnFe2O4 (NPM) modified with sulfonated polystyrene (PSS) in the adsorption of Pb(II) ions for the purpose of treating wastewater. The functionalization of the nanoparticle with the polymer aimed to increase the adsorption capacity and include the use of recyclable material due to its environmental importance. Adsorbents were characterized by Fourier transform infrared spectroscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, scanning electron microscopy, atomic force microscopy, elemental analysis, thermogravimetric analysis, point of zero charge, surface area, and porosity. PSS represented around 14% of the mass of magnetic nanoparticles of MnFe2O4 functionalized with sulfonated polystyrene (NPM-PSS) and the content of sulfonic groups was 17.18%. The Freundlich isotherm and pseudo second order kinetic models showed greater accuracy by the experimental data of adsorption of Pb (II) ions by NPM-PSS, whose adsorption capacity of nanoparticles ranged from 6.254 to 7.535 mg g−1.
The hydrothermal synthesis in mild conditions, and the structural characterizations and luminescence properties, of yttrium and erbium silicates Na3MSi3O9, M = Y(III) and Er(III), has been reported. ...Na3ErSi3O9 is a new infrared emitter with an emission spectrum displaying a broad visible band (300−700 nm) and a series of narrow infrared intra-4f11 4I13/2 → 4I15/2 lines. The number of Stark components detected (ca. 32) indicates the presence of four optically active environments, in accord with the structural data. When the temperature is raised from 14 to 300 K, the 4I13/2 → 4I15/2 transition integrated intensity increases by a factor of ca. 3.7. This remarkable and unusual behavior is the opposite temperature dependence usually observed for silicon-based materials. The samples' structures have been characterized by SEM, powder XRD, 29Si MAS NMR, and 23Na single- and multiple-quantum (MQ) MAS NMR. Using the recently introduced MQ MAS NMR FAM II (fast amplitude modulation of radio frequency pulses) technique, it has been possible to observe all 12 nonequivalent Na atoms in Na3YSi3O9, even those with large quadrupole coupling constants (in excess of 4 MHz).
The objective of this study was to use dry matter (DM) calibration models to sort ‘Palmer’ mangoes prior cold storage and to evaluate the physiological and chemical changes during the storage period. ...PLS model developed with fruit from 2015/2016 season was not adequate to predict DM content in fruit from 2016/2017 (not adjusted R2). Therefore, VIS‐NIR spectra from 2016/2017 season were incorporated into data set and a new model was developed (RMSEcv of 10.5 g.kg−1,
RP2 of 0.75). With the new model, ‘Palmer’ mangoes were sorted into two maturity stages (150 g.kg−1 and 110 g.kg−1) which resulted in quality differences mainly in relation to DM and SSC. Portable VIS‐NIR spectrometer can be used to sort fruit according to maturity stages based on DM content and this classification affect fruit quality during cold storage as fruit with higher DM (150 g.kg−1) presented better quality than fruit with lower DM (110 g.kg−1).
Practical applications
Although results can be found regarding the use of portable NIR spectrometers to estimate maturity in mango fruit, there are no studies stating the use of this method to sort fruit prior cold storage. Our results highlight that portable VIS‐NIR spectrometer can be used to sort fruit according to maturity stages based on dry matter (DM) content and this classification affects fruit quality during cold storage as fruit with higher DM (150 g.kg−1) presented better quality than fruit with lower DM (110 g.kg−1) at the end of the storage period.
Objetivou-se avaliar os efeitos dos aditivos própolis verde, própolis marrom e monensina sódica sobre as características de carcaça, avaliadas por ultra-som e pós-abate, os componentes corporais e o ...rendimento de cortes de cordeiros terminados em confinamento. Foram utilizados 32 cordeiros machos, com oito animais por tratamento, mantidos em confinamento por 64 dias. Os animais receberam dieta com relação volumoso:concentrado de 50:50, à base de feno de capim-tifton 85 (Cynodon spp.) e concentrado comercial. O delineamento experimental foi o de blocos ao acaso, com oito animais por dieta, distribuídos aleatoriamente de acordo com o peso: controle, dieta sem aditivo, própolis verde, própolis marrom e monensina sódica. Os rendimentos de carcaça (verdadeiro, quente e comercial) não diferiram entre os aditivos, com médias de 54,97; 44,89 e 41,81%, respectivamente. Os componentes corporais e rendimento de cortes comerciais não foram influenciados pelos aditivos utilizados nas dietas. A metodologia utilizada na determinação teve efeito nas medidas de área de olho-de-lombo (AOL) e espessura de gordura subcutânea (EGS), de modo que, pelo método tradicional, com medidas na carcaça, foram obtidas as maiores médias para AOL (12,14 vs. 9,08 cm²) e as menores para EGS (2,42 vs. 2,69 mm). A correlação entre as medidas de área de olho-de-lombo (AOL) da carcaça e aquelas obtidas por ultra-sonografia foi de 0,8597. Os aditivos não influenciaram as características de carcaça, os componentes corporais e o rendimento de cortes de ovinos terminados em confinamento. A realização de medidas ultra-sonográficas de AOL e marmoreio pode ser utilizada na avaliação de carcaça in vivo em ovinos.
This work was aimed at evaluating the effects of green propolis, brown propolis and sodic monensin aditives on the carcass characteristics by means of ultrasound and after-slaughter measures such as carcass non-components and yield of retail products from lambs finished in feedlot system. Thirty-two male lambs, with eight animal per treatment, were feedlot during 64 days. The animals were fed a diet with roughage:concentrate ratio of 50:50, composed of Tifton 85 hay grass (Cynodon spp.) and commercial concentrate. The experimental design was a randomized block design, with eight animals randomly assigned according to weight and the following treatments: control, diet without additive, green propolis, brown propolis and sodic monensin. The true, hot and commercial carcass percentage did not differ between treatments, with means of 54.97; 44.89 and 41.81%, respectively. Carcass non-components and yield of retail products were not influenced by treatments. The methodology used in the determinations affected the LEA and FT measures, so that the traditional method, obtained through measures in the carcass presented the highest averages for LEA (12.14 vs. 9.08 cm²) and lowest for FT (2.42 vs. 2.69 mm). The correlation between the of loin eye area (LEA) measures of the carcass with those obtained by ultrasound scan was 0.8597. The additives did not influence the carcass characteristics, non- components and yield of retail products from lambs finished in feedlot system. The performance of LEA and marbling ultrasound measures can be used in the in vivo carcass evaluation in sheep.
Multilayer Graphene Films Obtained by Dip Coating Technique Machuno, Luis Gustavo Baptista; Oliveira, Alex Ricardo; Furlan, Renan Hermógenes ...
Materials research (São Carlos, São Paulo, Brazil),
08/2015, Letnik:
18, Številka:
4
Journal Article
Recenzirano
Odprti dostop
A dip coating system was projected and constructed to deposit a large range of thin films onto solid substrates. A microcontroller was used to control the deposition system. As an example of ...application multilayer graphene (MLG) films were deposited onto glass slices in order to obtain conductive films with relatively good light transmittance. The MLG flakes were obtained using natural graphite and isopropyl alcohol resulting in three dispersions treated in ultrasound for 30, 60 and 90 minutes, respectively. Using atomic force microscopy, UV-Vis spectrometry and an electrometer the film characterizations were performed. MLG flakes about 13 nm thick, 10 mmu super(2) of area were observed using AFM. In films obtained with 35 immersions the electrical resistance and the resistance sheet reached 1.8 kohm and 1.9kohm/square respectively. The light transmittance reached 10-20% while films obtained with dispersions treated for 60 and 90 minutes were electrically continuous. Thus, conductive films can be used in chemiresistor sensors, electrochemical and supercapacitors electrodes.
Se planteó la hipótesis de que es posible que el inóculo de diferentes especies de rumiantes con capacidades digestivas diferentes que se alimentan de un determinado forraje puede mostrar diferentes ...utilizaciones de alimento en comparación con otras especies de rumiantes. Se evaluaron cinco gramíneas Brachiaria: B. decumbens cv. Basilisk, B. decumbens acceso D70, B. humidicola cv. Tupi, B. humidicola cv. Común, y B. ruziziensis acceso R124, en dos edades de rebrote (21 y 42 d). Se analizó la producción, el contenido bromatológico, la digestibilidad de materia seca in vitro (DMSiv) y la digestibilidad de la fibra detergente neutro in vitro (DFDNiv) utilizando inóculos bovinos u ovinos. El experimento utilizó un diseño factorial de 5 × 2 × 2 y encontró efectos significativos para la variedad de gramínea y la edad de rebrote. Además, se encontraron interacciones significativas de gramínea × edad en la materia seca, la proteína cruda, la fibra detergente neutro y la fibra detergente ácido de la muestra total y lamina de la hoja. Hubo un efecto significativo de la variedad de gramínea y la edad de la gramínea en la masa del forraje, la relación lámina de la hoja/tallo, lámina de la hoja, tallo, material senescente y crecimiento. En los ensayos de la digestibilidad in vitro, el origen del inóculo mostró un efecto significativo en algunas variedades. Debido a las diferencias en los ensayos in vitro, se recomendó el uso de inóculos específicos de las especies para las evaluaciones de alimentos según el animal al que se destina. Asimismo, B. decumbens cv. Basilisk presentó la mejor digestibilidad in vitro (DMSiv y DFDNiv) en inóculo bovino, mientras que B. humidicola cv. Tupi tuvo mejor digestibilidad in vitro (DMSiv y DFDNiv) en inóculo ovino.
Este artigo apresenta um estudo sobre o perfil da formação inicial do professor de Educação Infantil do Município de Teresina, considerando a exigência da LDB nº 9.394/96 que trata da formação mínima ...exigida para atuar nessa etapa de Educação Básica. O estudo compreendeu o universo de 2.342 docentes que atuavam na rede municipal e privada desse município. Trata-se de uma pesquisa de abordagem quantitativa, tendo como fonte os Microdados do Censo Escolar da Educação Básica do ano de 2017, disponibilizados no portal INEP. A extração desses Microdados e a posterior análise estatística foram realizadas com o auxílio do SPSS. A pesquisa revelou que, apesar dos avanços, o perfil de formação dos professores é diversificado. No entanto, considerando o percentual de docentes que já possuíam e estavam cursando licenciatura em Pedagogia, pode-se projetar uma melhoria desse perfil formativo a curto ou médio prazo.
O biogás é um combustível orgânico limpo que é produzido pela decomposição da matéria orgânica sob condições anaeróbias, composto de cerca de 55-65% de metano, 30-45% de dióxido de carbono, traços de ...sulfeto de hidrogênio e frações de vapor de água. A presença de outros compostos além do metano, embora ocorram em concentrações muito baixas, é um problema, uma vez que são prejudiciais para qualquer equipamento de processamento e restringem seu uso. Portanto, para atingir a composição padrão de biogás, é importante incluir as etapas de purificação antes de usar o biogás. As tecnologias tradicionais de purificação baseiam-se essencialmente no uso de métodos físicos e químicos, que também geram poluentes secundários e são caros. O presente estudo é uma revisão de diferentes processos de purificação de biogás baseados em membranas que são amplamente utilizados em todo o mundo e as principais tecnologias sendo desenvolvidas ou em pesquisa. Materiais de membrana apropriados, bem como um módulo eficiente e projeto de processo, determinam a competitividade com a tecnologia de separação convencional.
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