A. L. Leal-Cruz

Iron Influence on Copper Biosorption Using Anaerobic Sludge and Its Microstructural Characterization

With the purpose of determining the copper biosorption mechanism, iron influence on the bioremoval, and methane production in a batch system using an anaerobic sludge a systematic study was carried out. In addition, sludge was characterized before and after biosorption treatment by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). According to results, Fe(III) has effect on copper biosorption. At neutral pH and concentrations from 50 to 300 mg/L, copper biosorption increases. However, at concentrations >300 mg/L a reduction in biosorption is observed. During biosorption, Fe(III) does not have an effect on both methane production and methanogenic activity; consequently, it is possible establishing that methanogenic bacteria are active under these conditions. Results of analysis by EDS reveal the copper presence into diatoms (2.66w%). In addition, biosorption of copper is by means diatoms-bacteria-polimeric matrix, and it is also bioaccumulated into diatoms.

Annealing effect on structural, morphological, and optical behaviors of CBD-CdS nanostructured films for solar cells

In the current work, the effect of an annealing process on structural, morphological, and optical behaviors of cadmium sulfide thin films is presented. A chemical bath deposition method for cadmium sulfide deposition is based on the use of glycine as a complexing agent. Cadmium sulfide thin films were grown by chemical bath deposition and annealed in a nitrogen atmosphere at 0, 100, 150, 200, and 250 °C for 30 minutes. Crystallographic and morphological studies of CdS thin films were performed by scanning electron microscopy, X-ray photoelectron spectroscopy, atomic force microscopy, and X-ray diffraction. The optical behavior of CdS thin films was evaluated by UV-Visible spectroscopy and band gap values were calculated by approximation using a Tauc plot. After annealing, densified CdS films formed by nanostructured crystallites exhibit suitable band gap values and present relatively high transmittance in the visible region, allowing their application as a window material for solar cells.

Microstructural and Optical Characterization of Single and Multilayers of ZnO for TFTs Active Layer

Polymeric particles loaded with biocompatible magnetic nanoparticles are promising platforms to perform therapy and diagnostic of diseases, acting as the so called theranostic agents. In this work, magnetite nanoparticles were synthesized by coprecipitation method and encapsulated with Polycaprolactone (PCL) and Poloxamer 188 polymers through the innovative Nano Spray Drying technique. X-Ray Diffraction and Infrared Spectroscopy confirmed that the formed particles are composed by PCL, Poloxamer and magnetite, with amount of magnetite determined as 3% by Thermogravimetric Analysis. Particles present a superparamagnetic-like behaviour at 300 K, having negligible coercivity. Dynamic Light Scattering and Scanning Electron Microscopy indicated that the hydrodynamic diameters are of 49 nm for magnetite nanoparticles and of approximately 600 nm for encapsulated particles, with aspect analogous to a “nanocookie” of a PCL/Poloxamer blend with magnetite nanoparticles embedded in it. Cytotoxicity assays presented IC 50 superior to 2.5 mg/mL for healthy cells and a higher viability of cancer cells in comparison to control, suggesting that the particles may have affinity for tumours, which can be useful for the intended biological applications.

Repulsive Function in Potential Field Based Control with Algorithm for Safer Avoidance

In this article, a collision avoidance scheme based on potential functions is proposed. The first part of the paper is intended to establish the equations of the dynamic model of the vehicle, potential attractive functions and nested saturation controller. In the second part, the repulsive scheme is developed. Along with the repulsive scheme, the controller constants are optimized, in order to perform a safer avoidance maneuver. The advantages of the proposed repulsive schemes compared with a conventional repulsive function are demonstrated by simulations.

Microstructural and optical characterizations of highly stable nanospheres of crystalline CdS via selective approach

A novel and selective approach to obtain highly stable and capping nanospheres of crystalline cadmium sulfide (CdS) via solution growth in cadmium nitrate tetrahydrate-thiourea-ligand-pH buffer systems using a Taguchi experimental design is presented. CdS characterization is carried out by laser diffraction particle size analyzer, X-ray diffraction, scanning electron microscope/energy dispersive X-ray spectroscopy, and UV-Vis absorption spectroscopy. Synthesized nanospheres of crystalline CdS with an average crystal particle diameter of 37.5 nm and a capping layer thickness of 17.7–35.7 nm (73 to 115 nm as capped nanoparticles) keep size and form stable in aqueous solution. These crystalline CdS nanospheres exhibit a 2.46 eV band gap, as well as, an optical bandwidth comprises in the visible range with potential applications in solar cells.

LIGHTWEIGHT AND THERMAL BLOCKS FROM ZEOLITES AS AGGREGATED

The present research is focused on the design of mixtures containing zeolite (Z), as an alternative aggregate and their use in the production of blocks with lightweight and insulating properties that comply with the specific requirements of standards for its application in construction. To improve lightweight and insulating properties in blocks, first mixtures zeolitic sand/cement/lime (ZS/C/L) were prepared and their compression resistances were evaluated. After that, mixtures with the best compression resistances were choice to evaluate lightweight and insulating properties. Mixtures with the best properties (compression resistance, lightweight, and thermal conductivity) were use to make blocks by pressing in an industrial machine. Properties like compression resistance at 28 days after being cured, weight and thermal conductivity were evaluated in blocks and compared with those made out from traditional mixtures containing river sand (RS), C, and L. Results reveals that it is possible design alternative blocks with the following characteristics and properties: weight of 11 kg (15.4% lower than traditional block), thermal conductivity of 0.37 W/m°C (77.30% less than traditional bocks [1.63 W/m°C]), and compression resistance at 28 days of 74 kg/cm2 (above the resistance required [60 kg/cm2] in blocks).

Biosorptive Behavior of Aerobic Biomass Biofilm Supported on Clinoptilolite Zeolite for the Removal of Copper

The aim of this study was to determine the behavior of aerobic biomass biofilm supported on untreated clinoptilolite zeolite in the biosorption process to reduce the concentration of copper from synthetic solutions. A systematic study in batch and continuous systems was carried out. In addition, biomass and zeolite were characterized before and after biosorption treatment by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). According to results, zeolite only acts as a support for biomass and the study of SEM and EDS indicated that copper was absorbed by bacteria that are present on the surface of the zeolite. This study showed that untreated zeolite clinoptilolite acts as a support material for biomass during copper removal, and it may be an alternative of great interest for the immobilization of biomass in the restoration process of sites contaminated with heavy metals.

An Approach for Optimal Goal Position Assignment in Vehicle Formations

In this paper one methodology to solve the goal position assignment (GPA) problem is developed, this is, to assign the corresponding goal position (desired position) for a group of vehicles, knowing the initial positions and the established formation shape. By using this GPA methodology, it can be guaranteed that the formation will be reached in a minimum period of time and with lower collision risk compared with the other possible combinations of pairs “vehicles-goal position”. Hungarian algorithm was used as combinatorial optimization algorithm, which requires a cost matrix, therefore it is shown the way to compute the cost matrix to obtain the best GPA. In order to show the optimal behavior of the proposed cost matrix, three approaches of cost matrix were evaluated in simulations of quad-rotor formations. Also, the optimal behavior of the proposed GPA is proved with numerical values of some defined parameters to determine optimal performance. The formation control was based on potential functions, while the control law for each vehicle was based on nested saturation.

Synthesis and characterization of CBD-CdS nanospheres

Cadmium sulfide (CdS) nanospheres were successfully synthesized by chemical bath deposition (CBD) in the systems cadmium nitride tetrahydrate (Cd(NO₃)₂.4H₂O) - thiourea (NH₂CSNH₂) - complexing agent - pH buffer. An L₉ Taguchi experimental design was used with the purpose of determines the processing conditions to promote CdS nanospheres formation. For that reason, the processing parameters were varied at three levels, as follows: complexing agent (without complexing agent, glycine (NH₂CH₂COOH) and sodium citrate (Na₃C₆H₅O₇)), pH buffer (4 mL of borate, pH 11; 2 mL of ammonium hydroxide/ ammonium chloride, pH 10; and 2 mL of borate/pH 11), temperature (323.15, 338.15, and 353.15 K) and time (20, 30, and 40 minutes). Microstructural study was performed by SEM/EDS, XRD and laser particle size analyzer. According to characterization results, analysis of variance (ANOVA) and main effects, the processing conditions for CBD-CdS nanospheres synthesis are: cadmium nitride (Cd(NO₃)₂.4H₂O), thiourea (NH₂CSNH₂), glycine as complexing agent, and borate as buffer (2 mL) at 338.15 K for 40 minutes.

TRANSPARENT AND NANOSTRUCTURED CdS FILMS FOR INTEGRATED SYSTEMS IN FACADES

The aim of this work is process and characterize transparent and semitransparent CdS nanostructured films via chemical bath deposition, with potential application in solar cells for integrated systems in facades.