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The physiology of ex vitro pineapple ( Ananas comosus L. Merr. var MD-2) as CAM...

Pineapple is one of the most important tropical crops worldwide. The use of Temporary Immersion Bioreactors (TIB) for the first stages of pineapple propagation enables precise control of plant growth, increases the rate of plant multiplication, decreases space, energy and labor requirements for pineapple plants in commercial micropropagation. Once the plantlets are ready to be taken from the reactors, they are ...

Soybean oil transesterification by the use of a microwave flow system

The production of methyl esters from soybean transesterification by the use of a microwave flow system has been investigated. A household microwave was modified as a biodiesel reactor for continuous transesterification. The effects of temperature at the exit point (50–110 °C), the methanol/oil molar ratio (3:1, 6:1, 9:1 and 12:1) and the catalyst concentration (0.5%, 1.0% and 1.5% in weight of KOH) were evaluat...

Transesterification of castor oil under ultrasonic irradiation conditions: prel...

In this work, the preliminary results obtained in the transesterification of castor-oil with methanol in the presence of ultrasonic irradiations, are presented. The fundamental objective was to study the acceleration that the ultrasound causes in the reaction rate. The effect of different operating variables, such as frequency and supplied power dissipation, catalyst (KOH) concentration and methanol oil molar r...

Admittance spectroscopy of Cu2ZnSnS4 based thin film solar cells

In this report, we propose an AC response equivalent circuit model to describe the admittance measurements of Cu2ZnSnS4 thin film solar cell grown by sulphurization of stacked metallic precursors. This circuit describes the contact resistances, the back contact, and the heterojunction with two trap levels. The study of the back contact resistance allowed the estimation of a back contact barrier of 246 meV. The ...

Growth and characterization of Cu2ZnSn(S,Se)4 thin films for solar cells

Cu2ZnSnS4 (CZTS) and Cu2ZnSnSe4 (CZTSe) with their band gap energies around 1.45 eV and 1.0 eV, respectively, can be used as the absorber layer in thin film solar cells. By using a mixture of both compounds, Cu2ZnSn(S,Se)4 (CZTSSe), a band gap tuning may be possible. The latter material has already shown promising results such as solar cell efficiencies up to 10.1%. In this work, CZTSSe thin films were grown in...

Laser treatment for verrucous hemangioma

Laser treatment for verrucous hemangioma

Photoluminescence and electrical study of fluctuating potentials in Cu2ZnSnS4-b...

In this work, we investigated structural, morphological, electrical, and optical properties from a set of Cu2ZnSnS4 thin films grown by sulfurization of metallic precursors deposited on soda lime glass substrates coated with or without molybdenum. X-ray diffraction and Raman spectroscopy measurements revealed the formation of single-phase Cu2ZnSnS4 thin films. A good crystallinity and grain compactness of the f...

Study of optical and structural properties of Cu2ZnSnS4 thin films

Cu2ZnSnS4 is a promising semiconductor to be used as absorber in thin film solar cells. In this work, we investigated optical and structural properties of Cu2ZnSnS4 thin films grown by sulphurization of metallic precursors deposited on soda lime glass substrates. The crystalline phases were studied by X-ray diffraction measurements showing the presence of only the Cu2ZnSnS4 phase. The studied films were copper ...

Coartação de aorta em crianças até um ano : análise de 20 anos de experiência

Objetivo Revisão da experiência com diversas técnicas de correção empregadas, nos últimos 20 anos, em crianças menores de um ano de idade. Métodos No período de 1978 a 1998, foram operados 148 pacientes (pc) consecutivos com coartação de aorta (CoAo) com até um ano de idade, com ou sem defeitos intracardíacos associados. A idade apresentou mediana de 50 dias, 92 pc do sexo feminino (62,1%). O peso foi de 4.367±...