Luminescence Dynamics of Silica-Encapsulated Quantum Dots During Optical Trapping

"This document is the Accepted Manuscript version of a Published Work that appeared in final form in The Journal of Physical Chemistry C, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://pubs.acs.org/doi/10.1021/acs.jpcc.6b11867."[EN] The trade-off between photobrightening and photobleaching controls the emission stability of colloidal quantum dots. This balance is critical in optical trapping configurations, where irradiances that confine and simultaneously excite the nanocrystals in the focal region cannot be indefinitely lowered. In this work, we studied the photobrightening and bleaching behaviors of two types of silica-encapsulated quantum dots excited upon two-photon absorption in an optical trap. The first type consists of alloyed CdSeZnS quantum dots covered with a silica shell. We found that the dynamics of these as-prepared architectures are similar to those previously reported for bare surface-deposited quantum dots, where thousands of times smaller irradiances were used. We then analyzed the same quantum dot systems treated with an extra intermediate sulfur passivating shell for the better understanding of the surface traps influence in the temporal evolution of their emission in the optical trap. We found that these latter systems exhibit better homogeneity in their photodynamic behavior compared to the untreated ones. These features strengthen the value of quantum dot preparations in optical manipulation as well as for applications where both long and maximal emission stability in physiological and other polar media are required.The authors thank A. Blanco and D. Granados for fruitful discussion and S. de Lorenzo for technical help. H.R-R. is supported by an FPI-UAM fellowship and M. A. by a contract from Fundacion IMDEA Nanociencia. The research leading to these results has received funding from the Spanish Ministry of Economy and Competitiveness (grant numbers MAT2015-71806-R and FIS2015-67367-C2-1-P), from Comunidad de Madrid (S2013/MIT-2740) and from UAM-Banco Santander (CEAL-AL/2015-15).Rodríguez-Rodríguez, H.; Acebrón, M.; Juárez, B.; Arias-Gonzalez, JR. (2017). Luminescence Dynamics of Silica-Encapsulated Quantum Dots During Optical Trapping. The Journal of Physical Chemistry C. 121(18):10124-10130. https://doi.org/10.1021/acs.jpcc.6b11867S10124101301211

Effect of cooling rate during solidification on the hard phases of M23C6-type of cast CoCrMo alloy

Microstructural morphology of CoCrMo alloy by control of the cooling rate during the solidification was investigated. Samples were obtained using both an induction furnace for slow cooling rate and electric arc furnace for fast cooling rate. Microstructural characterizations were performed with metallographic techniques. It was found that the difference between the formation temperature of hard secondary phases of M23C6-type carbides determine the reduction of carbide size by increasing the cooling rate

Effect of cooling rate during solidification on the hard phases of M23C6-type of cast CoCrMo alloy

Microstructural morphology of CoCrMo alloy by control of the cooling rate during the solidification was investigated. Samples were obtained using both an induction furnace for slow cooling rate and electric arc furnace for fast cooling rate. Microstructural characterizations were performed with metallographic techniques. It was found that the difference between the formation temperature of hard secondary phases of M23C6-type carbides determine the reduction of carbide size by increasing the cooling rate

Photoluminescence Activation of Organic Dyes via Optically Trapped Quantum Dots

This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Nano, copyright © American Chemical Society after peer review and technical editing by the publisher.[EN] Laser tweezers afford quantum dot (QD) manipulation for use as localized emitters. Here, we demonstrate fluorescence by radiative energy transfer from optically trapped colloidal QDs (donors) to fluorescent dyes (acceptors). To this end, we synthesized silica-coated QDs of different compositions and triggered their luminescence by simultaneous trapping and two-photon excitation in a microfluidic chamber filled with dyes. This strategy produces a near-field light source with great spatial maneuverability, which can be exploited to scan nanostructures. In this regard, we demonstrate induced photoluminescence of dye-labeled cells via optically trapped silica-coated colloidal QDs placed at their vicinity. Allocating nanoscale donors at controlled distances from a cell is an attractive concept in fluorescence microscopy because it dramatically reduces the number of excited dyes, which improves resolution by preventing interferences from the whole sample, while prolonging dye luminescence lifetime due to the lower power absorbed from the QDs.H.R.-R. is supported by an FPI-UAM 2015 fellowship (BES-2009-027909). Authors acknowledge funding from the Spanish Ministry of Economy and Competitiveness through MAT2017-85617-R and MAT2015-71806-R. B.H.J. acknowledges financial support from the Spanish Ministry of Economy and Competitiveness, through the Maria de Maeztu (IFIMAC) and Severo Ochoa (IMDEA Nanoscience) Programmes for Units of Excellence in R&D.Rodríguez-Rodríguez, H.; Acebrón, M.; Iborra, F.; Arias-Gonzalez, JR.; Juárez, B. (2019). Photoluminescence Activation of Organic Dyes via Optically Trapped Quantum Dots. ACS Nano. 13(6):7223-7230. https://doi.org/10.1021/acsnano.9b02835S7223723013

Instituto Internacional de Investigaci ́on e Innovaci ́on del Envejecimiento

El Instituto Internacional de Investigaci on e Innovaci on del Envejecimiento es un proyecto transfronterizo y multidisciplinar centrado en la mejora de la calidad de vida de los ancianos mediante el uso de la tecnolog a. En este proyecto colaboran la Universidad de Evora, el Instituto Polit ecnico de Porto Alegre, el Instituto Polit ecnico de Beja, la Administraci on Regional de Salud de Alentejo y la Universidad de Extremadura. Los objetivos del proyecto se centran en comprender los aspectos biom edicos, funcionales y psicol ogicos del envejecimiento; generar nuevos modelos y procesos de cuidado a ancianos y desarrollar soluciones tecnol ogicas que contribuyan a la salud y calidad de vida de los ancianos y a la sostenibilidad de los servicios

Efecto de la inoculación con hongos micorrízicos en el rendimiento de avena forrajera

Objective: The objective of the present study was to evaluate the effect of inoculation with two species of mycorrhizal fungi on the yield of forage oats. Design / methodology / approach: The method of pelletization and seed coating was used; The sowing went to volley. A completely randomized design with factorial arrangement (2x3x3) was used as factors: the two varieties, the HMA Glomus cubense and Glomus fasciculatum with a control and fertilization at 50% and 100% with a control with four repetitions. Results: The Chihuahua variety obtained a better yield, leaf stem ratio, leaf area index, number of leaves, leaf death, stem density and leaf death (2.50); in the other variables they were statistically equal. The Glomus cubense species was superior to Glomus fasciculatum in the yield variables (6.92 t DM ha-1) and in the death of leaves (4.68), but in the leaf area index (135.02), Glomus fasciculatum exceeded Glomus cubense. Limitations of the study / implications: yield in fodder production, producers apply high amounts of chemical fertilizers, whose excessive use negatively affects the soil resource. Findings / conclusions: The Chihuahua variety has better behavior and Glomus cubense exceeds Glomus fascicucatum in performanceObjetivo: El objetivo del presente estudio fue evaluar el efecto de inoculación con dos especies de hongos micorrízicos en el rendimiento de avena forrajera. Diseño/metodología/aproximación: Se utilizó el método de peletización y recubrimiento de semilla; la siembra fue al voleo. Se utilizó un diseño completamente al azar con arreglo factorial (2x3x3) se consideró como factores: las dos variedades, los HMA Glomus cubense y Glomus fasciculatum con un testigo y la fertilización al 50% y al 100% con un testigo con cuatro repeticiones. Resultados: La variedad Chihuahua obtuvo un mejor rendimiento, relación hoja tallo, índice de área foliar, número de hojas, muerte de hojas, densidad de tallos y en la muerte de hojas (2.50); en las demás variables fueron estadísticamente iguales. La especie Glomus cubense fue superior al Glomus fasciculatum en las variables rendimiento (6.92 t MS ha-1) y en la muerte de hojas (4.68), pero en el índice de área foliar (135.02), Glomus fasciculatum superó a Glomus cubense. Limitaciones del estudio/implicaciones: el rendimiento en la producción de forraje, los productores aplican cantidades elevadas de fertilizantes químicos, cuyo uso excesivo afecta negativamente el recurso suelo. Hallazgos/conclusiones: La variedad Chihuahua tiene mejor comportamiento y Glomus cubense en supera en rendimiento a Glomus fascicucatu

Imposition, resistance, and alternatives in the face of an interregional water crisis in Mexico: El Zapotillo project

En este dossier se analizan los complejos aspectos socio-políticos, económicos, hidrológicos, legales, entre otros, relacionados con la construcción del proyecto El Zapotillo, que incluye un trasvase del Río Verde entre los estados mexicanos de Jalisco y Guanajuato con consecuencias significativas paras las comunidades humanas y los ecosistemas. El Cuaderno de Trabajo presenta doce artículos escritos por especialistas en las diferentes dimensiones del proceso, e incluye el trabajo de estudiantes de doctorado, activistas, y miembros de las comunidades locales afecadas directamente por el proyecto. It is a dossier focused on the complex socio-political, economic, hydrological, legal and other aspects involving the construction of El Zapotillo project, which includes an inter-basin transfer of the Verde River between the Mexican states of Jalisco and Guanajuato with significant consequences for human communities and ecosystems. The Working Paper features twelve articles written by specialists in the different dimensions of the process, and includes the work of doctoral students, activists, and members of the local communities directly affected by the project.ITESO, A.C.Universidad de BernaEl Colegio de JaliscoUNAMUniversidad de GuanajuatoUniversidad de GuadalajaraCartocríticaIMDECCIDEComité Salvemos Temacapulín, Acasico y PalmarejoColectivo de Abogad@

Acquisition of uropygial gland microbiome by hoopoe nestlings

Mutualistic symbioses between animals and bacteria depend on acquisition of appropriate symbionts while avoiding exploitation by non-beneficial microbes. The mode of acquisition of symbionts would determine, not only the probability of encountering but also evolutionary outcomes of mutualistic counterparts. The microbiome inhabiting the uropygial gland of the European hoopoe (Upupa epops) includes a variety of bacterial strains, some of them providing antimicrobial benefits. Here, the mode of acquisition and stability of this microbiome is analyzed by means of Automated rRNA Intergenic Spacer Analysis and two different experiments. The first experiment impeded mothers’ access to their glands, thus avoiding direct transmission of microorganisms from female to offspring secretions. The second experiment explored the stability of the microbiomes by inoculating glands with secretions from alien nests. The first experiment provoked a reduction in similarity of microbiomes of mother and nestlings. Interestingly, some bacterial strains were more often detected when females had not access to their glands, suggesting antagonistic effects among bacteria from different sources. The second experiment caused an increase in richness of the microbiome of receivers in terms of prevalence of Operational Taxonomic Units (OTUs) that reduced differences in microbiomes of donors and receivers. That occurred because OTUs that were present in donors but not in receivers incorporated to the microbiome of the latter, which provoked that cross-inoculated nestlings got similar final microbiomes that included the most prevalent OTUs. The results are therefore consistent with a central role of vertical transmission in bacterial acquisition by nestling hoopoes and support the idea that the typical composition of the hoopoe gland microbiome is reached by the incorporation of some bacteria during the nestling period. This scenario suggests the existence of a coevolved core microbiome composed by a mix of specialized vertically transmitted strains and facultative symbionts able to coexist with them. The implications of this mixed mode of transmission for the evolution of the mutualism are discussedMinisterio de Ciencia e Innovación (España)Junta de Andalucí

Human immunodeficiency virus/hepatits C virus coinfection in Spain: Elimination is feasible, but the burden of residual cirrhosis will be significant

Background We assessed the prevalence of antibodies against hepatitis C virus (HCV-Abs) and active HCV infection in patients infected with human immunodeficiency virus (HIV) in Spain in 2016 and compared the results with those of similar studies performed in 2002, 2009, and 2015. Methods The study was performed in 43 centers during October-November 2016. The sample was estimated for an accuracy of 2% and selected by proportional allocation and simple random sampling. During 2016, criteria for therapy based on direct-acting antiviral agents (DAA) were at least significant liver fibrosis, severe extrahepatic manifestations of HCV, and high risk of HCV transmissibility. Results The reference population and the sample size were 38904 and 1588 patients, respectively. The prevalence of HCV-Abs in 2002, 2009, 2015, and 2016 was 60.8%, 50.2%, 37.7%, and 34.6%, respectively (P trend <.001, from 2002 to 2015). The prevalence of active HCV in 2002, 2009, 2015, and 2016 was 54.0%, 34.0%, 22.1%, and 11.7%, respectively (P trend <.001). The anti-HCV treatment uptake in 2002, 2009, 2015, and 2016 was 23.0%, 48.0%, 59.3%, and 74.7%, respectively (P trend <.001). In 2016, HCV-related cirrhosis was present in 7.6% of all HIV-infected individuals, 15.0% of patients with active HCV, and 31.5% of patients who cleared HCV after anti-HCV therapy. Conclusions Our findings suggest that with universal access to DAA-based therapy and continued efforts in prevention and screening, it will be possible to eliminate active HCV among HIV-infected individuals in Spain in the short term. However, the burden of HCV-related cirrhosis will continue to be significant among HIV-infected individuals

Dominant Negative Mutants of Bacillus thuringiensis Cry1Ab Toxin Function as Anti-Toxins: Demonstration of the Role of Oligomerization in Toxicity

BACKGROUND:Bacillus thuringiensis Cry toxins, that are used worldwide in insect control, kill insects by a mechanism that depends on their ability to form oligomeric pores that insert into the insect-midgut cells. These toxins are being used worldwide in transgenic plants or spray to control insect pests in agriculture. However, a major concern has been the possible effects of these insecticidal proteins on non-target organisms mainly in ecosystems adjacent to agricultural fields. METHODOLOGY/PRINCIPAL FINDINGS:We isolated and characterized 11 non-toxic mutants of Cry1Ab toxin affected in different steps of the mechanism of action namely binding to receptors, oligomerization and pore-formation. These mutant toxins were analyzed for their capacity to block wild type toxin activity, presenting a dominant negative phenotype. The dominant negative phenotype was analyzed at two levels, in vivo by toxicity bioassays against susceptible Manduca sexta larvae and in vitro by pore formation activity in black lipid bilayers. We demonstrate that some mutations located in helix alpha-4 completely block the wild type toxin activity at sub-stoichiometric level confirming a dominant negative phenotype, thereby functioning as potent antitoxins. CONCLUSIONS/SIGNIFICANCE:This is the first reported case of a Cry toxin dominant inhibitor. These data demonstrate that oligomerization is a fundamental step in Cry toxin action and represent a potential mechanism to protect special ecosystems from the possible effect of Cry toxins on non-target organisms