Silver nanoparticle-cellulose composite for thin-film microextraction of Cd and Pb as dithiocarbamate derivatives followed by inductively-coupled plasma mass spectrometry determination

Financiado para publicación en acceso aberto: Universidade de Vigo/CISUGPreconcentration of Cd and Pb at ultratrace level in waters following filtration through silver nanoparticles-cellulose composites used for thin-film microextraction was performed. The new procedure was based on the formation of pyrrolidine dithiocarbamate (APDC) derivatives, which showed a large affinity toward the AgNPs. For this purpose, cellulose filters modified with AgNPs were prepared in situ upon reduction of silver ions by sodium tetrahydroborate. The effect of several experimental parameters such as the kind of derivatization agent and its concentration, sample pH, desorption conditions and volume of filtered sample was assessed. Cd and Pb were quantitated in the eluates by inductively coupled plasma-mass spectrometry (ICP-MS). Filters were characterized by scanning electron microscopy (SEM) in backscattering electron mode and combined with energy dispersive X-ray spectrometry, showing the presence of Ag and S in the cellulose filter. The repeatability expressed as relative standard deviation (RSD,%) was 1.4% for Cd and 5.8% for Pb. Methodological detection limits were 0.6 and 8.5 ng/L for Cd and Pb, respectively. The method was applied to several environmental waters.Agencia Estatal de Investigación | Ref. RTI2018-093697-B-I0

Drivers of Bird- Window Collisions in Florida International University’s Modesto A. Maidique Campus

Bird-window collisions are among the top leading causes of death for birds in North America. Studies have found primary drivers of bird-window collisions to be window area, building size, and presence of vegetation around the buildings. We hypothesized that higher window area and vegetation would increase birdwindow collisions, with an inverse relationship between number of stories and bird-window collisions. Surveys were conducted for 21 consecutive days around six buildings at Florida International University (FIU) in October 2014. Using ArcGIS, 50m buffers were created around each building to calculate percent vegetation and ImageJ was used to calculate percent window cover. We collected 10 bird carcasses and 13 feather piles assumed to represent bird-window collisions. Most of the collisions (8 out of 21) occurred at the building with the lowest percent vegetation and low window area. Our sample size limits our ability to make general conclusions, however, our data is a part of a larger collaborative project that includes over 30 campuses across North America. Results from this larger project could provide insight on whether the magnitude of bird-window collisions relates to landscape structure and functional connectivity

Detection of gases and organic vapors by cellulose-based sensors

The growing interest in the development of cost-effective, straightforward, and rapid analytical systems has found cellulose-based materials, including cellulose derivatives, cellulose-based gels, nanocellulosic materials, and the corresponding (nano)cellulose-based composites, to be valuable platforms for sensor development. The present work presents recent advances in the development of cellulose-based sensors for the determination of volatile analytes and derivatives of analytical relevance. In particular, strategies described in the literature for the fabrication and modification of cellulose-based substrates with responsive materials are summarized. In addition, selected contributions reported in the field of paper-based volatile sensors are discussed, with a particular emphasis on quick response (QR) code paper-based platforms, intelligent films for food freshness monitoring, and sensor arrays for volatile discrimination purposes. Furthermore, analytical strategies devised for the determination of ionic species by in situ generation of volatile derivatives in both paper-based analytical devices (PADs) and microfluidic PADs will also be described.Universidade de Vigo/CISUGAgencia Estatal de Investigación | Ref. RTI2018-093697-B-I0

Tolerance and hyperaccumulation of a mixture heavy metals (Cu, Pb , Hg and Zn) by four aquatic macrophytes

El propósito de este trabajo fue comparar la tolerancia a la exposición de una mezcla de los metales (Cu2+, Pb2+, Hg2+ y Zn2+) así como el nivel de hiperacumulación en Typha latifolia, Lemna minor, Eichhornia crassipes y Myriophyllum acuaticum, para proponer un sistema de bioacumulación selectiva que permita la biorremediación eficiente de cuerpos de agua contaminadosIn the present investigation, four macrophytes, namely Typha latifolia (L.), Lemna minor (L.), Eichhornia crassipes (Mart.) Solms-Laubach, and Myriophyllum aquaticum (Vell.) Verdc, were evaluated for their heavy metal (Cu, Pb, Hg, and Zn) hyperaccumulation potential under laboratory conditions. Tolerance analyses were performed for 7 days of exposure at five different treatments of the metals mixture (CuC2, HgC2, PbC2, and ZnC2). The production of chlorophyll and carotenoids was determined at the end of each treatment. L. minor revealed to be sensitive, because it did not survive in all the tested concentrations after 72 hours of exposure. E. crassipes and M. aquaticum displayed the highest tolerance to the metals mixture. For the most tolerant species of aquatic macrophytes, The removal kinetics of E. crassipes and M. aquaticum was carried out, using the following mixture of metals: Cu (0.5 mg/L) and Hg, Pb, and Zn 0.25 mg/L. The obtained results revealed that E. crassipes can remove 99.80% of Cu, 97.88% of Pb, 99.53% of Hg, and 94.37% of Zn. M. aquaticum withdraws 95.2% of Cu, 94.28% of Pb, 99.19% of Hg, and 91.91% of Zn. The obtained results suggest that these two species of macrophytes could be used for the phytoremediation of this mixture of heavy metals from the polluted water bodies

Análisis econométrico sobre el consumo de agua subterránea por el sector agropecuario en Guanajuato, México

Los factores que afectan el consumo de agua subterránea en los sectores agrícola de riego y pecuario en el estado de Guanajuato fueron estimados con un modelo de ecuaciones simultáneas, para lo cual se utilizó información estadística anual de 1980 a 2007. Los resultados encontrados muestran que la cantidad consumida de agua responde de manera inelástica a cambios en el precio, con elasticidades de -0.0527 para la agricultura de riego y de -0.00486 para la ganadería. Estas elasticidades indican que en el sector pecuario el consumo de agua es más insensible a cambios en el precio, en comparación a la agricultura de riego y, por ende, políticas de administración del consumo deberán considerar aumentos en el precio del agua en este sector.Los factores que afectan el consumo de agua subterránea en los sectores agrícola de riego y pecuario en el estado de Guanajuato fueron estimados con un modelo de ecuaciones simultáneas, para lo cual se utilizó información estadística anual de 1980 a 2007. Los resultados encontrados muestran que la cantidad consumida de agua responde de manera inelástica a cambios en el precio, con elasticidades de -0.0527 para la agricultura de riego y de -0.00486 para la ganadería. Estas elasticidades indican que en el sector pecuario el consumo de agua es más insensible a cambios en el precio, en comparación a la agricultura de riego y, por ende, políticas de administración del consumo deberán considerar aumentos en el precio del agua en este sector

The nuclear receptor LXRα controls the functional specialization of splenic macrophages.

Macrophages are professional phagocytic cells that orchestrate innate immune responses and have considerable phenotypic diversity at different anatomical locations. However, the mechanisms that control the heterogeneity of tissue macrophages are not well characterized. Here we found that the nuclear receptor LXRα was essential for the differentiation of macrophages in the marginal zone (MZ) of the spleen. LXR-deficient mice were defective in the generation of MZ and metallophilic macrophages, which resulted in abnormal responses to blood-borne antigens. Myeloid-specific expression of LXRα or adoptive transfer of wild-type monocytes restored the MZ microenvironment in LXRα-deficient mice. Our results demonstrate that signaling via LXRα in myeloid cells is crucial for the generation of splenic MZ macrophages and identify an unprecedented role for a nuclear receptor in the generation of specialized macrophage subsets