ZnO on rice husk: a sustainable photocatalyst for urban air purification

A cost-effective and sustainable De-NOx photocatalyst is prepared usingzinc acetate and rice husk. ZnO@SiO2samples are obtained from the calcination of a homogenised precursor mixture at 600 C. ZnO nanoparticles (70 –180 nm) grow aggregated in spheres and well dispersed (40 –53 m2g-1surface area) covering the silicon skeleton. The corresponding band gap for ZnO@SiO2photocatalysts was estimated at3.1 –3.2 eV. When the samples are irradiated by sunlight in anitrogen oxide atmosphere the NO HNO2NO2NO3-photochemical oxidation takes place. In comparison to unsupported ZnO and TiO2-P25, ZnO@SiO2samples exhibit high NOXremoval values (70 %) and outstanding selectivity (> 90%), the latter related to the sensitivity of zinc oxide towards NO2gas. This new photocatalyst is easily recyclable and reusabl

Zn-Al layered double hydroxides as efficient photocatalysts for NOx abatement

In this study,we report that layered double hydroxides (LDH) exhibited high photocatalytic activitiesin degrading NOx gases for the first time. ZnAl-CO3LDHs with a 1.5 to 3.0 Zn/Al ratio were prepared by a coprecipitation method both with and without hydrothermal treatment.Syntheses were carried out with high and low metal concentrations, the latter being the most favorablein obtaining pure LDHs in the whole Zn/Al ratio range. The samples were characterized by different techniques suchas PXRD, FT-IR, ICP mass, TGA, SBET, SEM and Diffuse reflectance (DR). The LDH particlesgrew as well-defined hexagonal nanolayers, whosesize and crystallization dependedon the synthetic procedure and the Zn/Al ratio. Those samples with lower crystallinity exhibit the highest specific surface area values (> 50 m2·g-1). The ZnAl-CO3LDHs were UV light responsive with band–gap valuescloseto 3.5 eV. The LDH photocatalysts show a high performance towards the photochemical oxidation process of NO gas, withefficiencies of around 55 %. Remarkably, the ZnAl-CO3photocatalysts exhibit an impressive selectivity towards the deNOx process, avoiding the emission of the toxic NO2gas into the atmosphere. Interestingly,these promising deNOx results are repeated when working for a long irradiation period or with the highest concentration of NO in polluted atmospheres

New results in nonlinear state estimation using extended unbiased fir filtering

This paper discusses two algorithms of extended unbiased FIR (EFIR) filtering of nonlinear discrete-time state-space models used in tracking and state estimation. The basic algorithm employs the extended nonlinear state and observation equations. The modified algorithm utilizes the nonlinear-to-linear conversion of the observation equation which is provided using a batch EFIR filter having small memory. Unlike the extended Kalman filter (EKF), both EFIR algorithms ignore the noise statistics and demonstrate better robustness against temporary model uncertainties. These algorithms require an optimal horizon in order to minimize the mean square error. Applications are given for robot indoor self-localization utilizing radio frequency identification tags

The Inhibitive Effect of Sebacate-Modified LDH on Concrete Steel Reinforcement Corrosion

In recent decades, layered double hydroxides (LDH) have been proposed as innovative corrosion inhibitors for reinforced concrete. Their protective action is based on the ability to intercalate specific anions in the interlayer and on their ability to exchange the intercalated anion. In the present study, an organically charged LDH, with sebacate anions in the interlayer (LDH-S), is proposed as a water-repellent additive for mortar. The waterproofing efficiency of LDH-S and the associated corrosion inhibition ability has been evaluated in reinforced mortar samples. A 42% decrease in the water capillary absorption coefficient has been estimated when 3% LHD-S is added to a mortar. Both the passivation processes of the steel rebars during the curing period and the initiation of corrosion due to chloride exposure have been studied by electrochemical measurements. Three different mortars have been evaluated: reference mortar (REF), mortar with Mg-Al LDH (LDH), and mortar with LDH-sebacate (LDH-S). The latter has shown an important protective capacity for preventing the initiation of corrosion by chloride penetration, with an inhibitory efficiency of 74%. The presence of LDHs without sebacate in the interlayer also improved the performance of the mortar against rebar corrosion, but with lower efficiency (23% inhibitory efficiency). However, this protection is lost after continued chloride exposure over time, and corrosion initiates similarly to the reference mortar. The low corrosion current density values registered when LDH-S is added to the mortar may be related to the increased electrical resistance recorded in this mortar

Effects of Fe3+ substitution on Zn-Al layered double hydroxides for enhanced NO photochemical abatement

In this work the ability of ZnAlFe-CO3 layered double hydroxides (LDHs) as highly efficient UV-Vis light photocatalysts for the photochemical oxidation of NO gas was studied. LDHs with 3.5 to 4.1 M2+/M3+ and 0.33 to 1.55 Fe/Al ratios were prepared by a coprecipitation method. The samples were characterized by different techniques such as XRD, XPS, FT-IR, ICP-MS, TG, SBET, SEM and Diffuse reflectance (DR). The increased presence of the Fe3+ ions gave rise to changes in the structure, morphology and optical properties of the LDHs. The prepared ZnAlFe-CO3 systems exhibited increased surface area and enhanced visible-light absorbance. The photochemical NO abatement resulted in outstanding conversion efficiency (56 %) and selectivity (93 %) for the iron containing samples, due to a decrease of the e-/h+ recombination, higher generation of ⋅O2- and ⋅OH radicals and their NO2 adsorption ability

Synthesis, characterization and biological evaluation of octyltrimethylammonium tetrathiotungstate

Octyltrimethylammonium tetrathiotungstate salt (ATT-C8) was synthesized and its ability to chelate copper was evaluated. The biological and toxic aspects were evaluated by in vitro and in vivo assays, using bovine aorta endothelial cells (BAEC) and zebrafish (Danio rerio) embryos. The obtained results suggest that ATT-C8 has better biocompatibility, showing a significantly lower lethal concentration 50 (LC50) value in comparison to ammonium tetrathiotungstate (ATT). Zebrafish embryos assay results indicate that both tetrathiotungstate salts at the studied concentrations increase the hatching time. Even more, an in vivo assay showed that synthesized materials behave as copper antagonists and have the ability to inhibit its toxicological effects. Also, both materials were found to be active for the in vitro 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The characterization of the materials was carried out using the following spectroscopic techniques: Ultraviolet–Visible (UV–Vis), Fourier Transform Infrared (FTIR) and proton nuclear magnetic resonance (1H-NRM).The authors gratefully acknowledge the financial support provided by the UABC-UNAM SENERCONACYT 117373 project. Authors thank David Navas Fernandez for excellent technical support in these experiments, as well as Dr. Raúl Romero Rivera for his valuable comments. The scientific work developed by MAM’s group is supported by grants PID2019-105010RB-I00 (Spanish Ministry of Science, Innovation and Universities), and UMA18- FEDERJA-220 (Andalusian Government and FEDER) and funds from group BIO 267 (Andalusian Government), as well as funds from ‘‘Plan Propio de Investigación y Transferencia’’ (U. Málaga)

Incidence and management of inguinodynia after inguinal plasty

Background: Hernia is defined as a defect of fascial and muscle-aponeurotic structures, allowing the protrusion of elements. The most frequent is inguinal region, prevailing in men 3:1 vs female. The most frequent complications are persistent chronic pain.Methods: A descriptive, prospective and cross-sectional study was performed in postoperative inguinal plasty patients, using a laparoscopic approach and open approach, the presence or absence of inguinodynia was studied using the visual analogue pain scale (VAS) and the Semmes-Weinstein monofilament, in addition to a systematic investigation in the following PubMed, Medline, Clinical Key and Index Medicus databases, with articles from July 2019 to April 2020.Results: Inguinodynia was present in laparoscopic surgery and open approach, 58 patients had inguinodynia at two weeks associated with the inflammatory response of the tissues and the presence of a foreign body (mesh), 77% of the patients with persistence of pain at 3 months reported mild pain (VAS 1-4), 21% moderate pain that did not limit their daily activities (VAS 5-8) and 2% of the patients reported severe pain which limited physical activity and effort   (VAS 9-10).Conclusions: Inguinodynia has an impact on hospital costs and quality life, we consider it is essential to domain the anatomical variants of the region. We propose an extensive follow-up of this group of patients, to make a comparison of diagnostic methods, as well as conservative management vs. modern techniques for pain control