E. Palacios-González

Evaluation of agave fiber delignification by means of microscopy techniques and image analysis.

Recently, the use of different types of natural fibers to produce paper and textiles from agave plants has been proposed. Agave atrovirens can be a good source of cellulose and lignin; nevertheless, the microstructural changes that happen during delignification have scarcely been studied. The aim of this work was to study the microstructural changes that occur during the delignification of agave fibers by means of microscopy techniques and image analysis. The fibers of A. atrovirens were obtained from leaves using convective drying, milling, and sieving. Fibers were processed using the Acetosolv pulping method at different concentrations of acetic acid; increasing acid concentration promoted higher levels of delignification, structural damage, and the breakdown of fiber clumps. Delignification followed by spectrometric analysis and microstructural studies were carried out by light, confocal laser scanning and scanning electron microscopy and showed that the delignification process follows three stages: initial, bulk, and residual. Microscopy techniques and image analysis were efficient tools for microstructural characterization during delignification of agave fibers, allowing quantitative evaluation of the process and the development of linear prediction models. The data obtained integrated numerical and microstructural information that could be valuable for the study of pulping of lignocellulosic materials.

Nanobiosensors in Food Science and Technology

Nanotechnology has already been applied in several fields, up to now, most of the research on nanotechnology focused on electronics such as communication, energy production, and pharmaceutical and the food industry. The knowledge gained from these sectors could be adapted for the improvement of food products, such as for applications in food safety and quality (e.g., detecting pesticides and microorganism identification), encapsulation, improving the efficiency of delivery of nutraceutical and bioactive compounds, and packing systems and food storage. The nanoscale devices are often manufactured with the view to imitate the nanodevices found in nature; one way to get these results is by means of the biosensors to detect, among others, proteins, DNA, enzymes, cells, membranes, and other natural biomolecules used as bioreceptors and selecting the right transduction method (electrochemical, mechanical, or optical) in order to get more sensitive, specific, and real-time results. This chapter provides an introduction to the nanosensor field including specific consideration of three main application areas (food, environmental, and pharmaceutical); it also describes the typical biosensor assay format used and is subsequently structured according to the biorecognition elements used (i.e., enzymes, cellular structures/cells, antibody/antigen, nucleic acids/DNA, bacteriophages). In addition, information about lab on a chip based on microelectromechanical systems (MEMS) and nanoelectromechanical systems (NEMS) technology is also provided.

Synthesis and Characterization of BiOCl Powders with Soft Templates

Bismuth oxychloride (BiOCl) powders were synthesized via a hydro/solvothermal method from BiCl3. Synthesis were performed in the presence of different capping agents namely polyvinylpyrrolidone (PVP), ethylenediamine (C2H4(NH2)2) or dextrose (C6H12O6). The reaction media, nature of capping agent, weight or molar ratio Bi:capping agent and temperature play an important role in the formation of well-defined morphology of BiOCl powders, which varies from melt crystals to plate-like structures. The as-obtained BiOCl/capping agent systems were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy and IR spectroscopy. Among the selected capping agents, the C2H4(NH2)2 promote a defined morphology of the BiOCl crystals being a potential soft template. BiOCl/C2H4(NH2)2 system synthesized in aqueous medium clearly illustrate the effect of the Bi:C2H4(NH2)2 ratio on the morphology of BiOCl powders. The photocatalytic activity of BiOCl/C2H4(NH2)2 (1:0.5 molar ratio or 0.5 equiv.) and TiO2:BiOCl composites were evaluated on the degradation of methylene blue (MB) under UV–Vis light irradiation and compared with commercial TiO2 (Degussa, P25). It was pointed out that BiOCl powders with well-defined rectangular plate-like morphology have a higher photocatalytic activity during MB photodegradation in comparison to TiO2:BiOCl composites and similar to commercial TiO2.