Band Structure Dynamics in Indium Wires

One-dimensional Indium wires grown on Si(111) substrates, which are metallic at high temperatures, become insulating below $\sim100$ K due to the formation of a Charge Density Wave (CDW). The physics of this transition is not conventional and involves a multiband Peierls instability with strong interband coupling. This CDW ground state is readily destroyed with femtosecond laser pulses resulting in a light-induced insulator-to-metal phase transition. The current understanding of this transition remains incomplete, requiring measurements of the transient electronic structure to complement previous investigations of the lattice dynamics. Time- and angle-resolved photo\-emission spectroscopy with extreme ultra-violet radiation is applied to this end. We find that the transition from the insulating to the metallic band structure occurs within $\sim660$ fs that is a fraction of the amplitude mode period. The long life time of the transient state ($>100$ ps) is attributed to trapping in a metastable state in accordance with previous work.Comment: 14 pages, 7 figure

Direct evidence for efficient ultrafast charge separation in epitaxial WS2_2/graphene heterostructure

We use time- and angle-resolved photoemission spectroscopy (tr-ARPES) to investigate ultrafast charge transfer in an epitaxial heterostructure made of monolayer WS$_2$ and graphene. This heterostructure combines the benefits of a direct gap semiconductor with strong spin-orbit coupling and strong light-matter interaction with those of a semimetal hosting massless carriers with extremely high mobility and long spin lifetimes. We find that, after photoexcitation at resonance to the A-exciton in WS$_2$, the photoexcited holes rapidly transfer into the graphene layer while the photoexcited electrons remain in the WS$_2$ layer. The resulting charge transfer state is found to have a lifetime of $\sim1$\,ps. We attribute our findings to differences in scattering phase space caused by the relative alignment of WS$_2$ and graphene bands as revealed by high resolution ARPES. In combination with spin-selective excitation using circularly polarized light the investigated WS$_2$/graphene heterostructure might provide a new platform for efficient optical spin injection into graphene.Comment: 28 pages, 14 figure

On the survival of Floquet-Bloch states in the presence of scattering

Floquet theory has spawned many exciting possibilities for electronic structure control with light with enormous potential for future applications. The experimental realization in solids, however, largely remains pending. In particular, the influence of scattering on the formation of Floquet-Bloch states remains poorly understood. Here we combine time- and angle-resolved photoemission spectroscopy with time-dependent density functional theory and a two-level model with relaxation to investigate the survival of Floquet-Bloch states in the presence of scattering. We find that Floquet-Bloch states will be destroyed if scattering -- activated by electronic excitations -- prevents the Bloch electrons from following the driving field coherently. The two-level model also shows that Floquet-Bloch states reappear at high field intensities where energy exchange with the driving field dominates over energy dissipation to the bath. Our results clearly indicate the importance of long scattering times combined with strong driving fields for the successful realization of various Floquet phenomena.Comment: 27 pages, 5 figue

Relationship between Serum Concentration of Uric Acid and Insulin Secretion among Adults with Type 2 Diabetes Mellitus

To determine the relationship between serum concentrations of uric acid and insulin secretion with hyperglycaemic clamp technique among adults with type 2 diabetes mellitus (DM2) without hyperuricemia, we carried out a cross-sectional study on 45 patients of both gender. We observed correlation between uric acid with male gender r = 0.710 (P = 0.001). Also correlation between uric acid and total insulin secretion was positive r = 0.295 (P = 0.049). As well as a positive correlation adjusted for body mass index was demonstrated for the first, second, and total phases of insulin secretion, respectively, r = 0.438 (P = 0.022), r = 0.433 (P = 0.022), and r = 0.439 (P = 0.024). Serum concentration of uric acid showed a positive relationship with the total phase of insulin secretion; even in states prior to hyperuricemia, uric acid can play an important role in the function of the beta cell in patients with DM2

Concientización y mejoramiento de gestión de residuos sólidos urbanos en San Isidro Mazatepec, Tala

En este proyecto se muestra la planeación y las acciones llevadas a cabo para mejorar las capacidades de la comunidad en cuanto al entendimiento de la problemática actual de residuos. Se reforzó la campaña de concientización a través de talleres en primaria, secundaria y preparatoria, donde se tocaron diversos temas que involucra residuos, se hizo un “día de documental” para causar un impacto visual, también se realizó un folleteo para que la información tuviera un mayor alcance. Se participó en el festival cultural exponiendo los avances de todos los proyectos que se están llevando a cabo en San Isidro. Se continuó con el plan de poner en marcha el centro de acopio con apoyo de estudiantes de la comunidad. Se crearon 3 “puntos limpios” y se dieron a conocer a los habitantes de la comunidad, también se especificaron los beneficios de separar la basura y el impacto positivo que tendrá en su comunidad.ITESO, A.C

Gestión de residuos sólidos urbanos en San Isidro Mazatepec, Tala

En este proyecto PAP verano 2018 San Isidro Mazatepec, nos enfocamos en generar un plan de gestión de residuos sólidos urbanos. Participó un equipo multidisciplinario conformado por ingenieros industriales, mecánicos, licenciados en relaciones industriales y en administración. La base del proyecto fue la problemática que existe en el poblado de San Isidro Mazatepec sobre la excesiva producción de residuos sólidos urbanos, la falta de espacios en donde realizar los depósitos de basura y la deplorable situación del sistema de gestión actual, así como del relleno sanitario del poblado. Se atacó la problemática desde la estrategia de implementación de un sistema de gestión de residuos, en donde se acondicionó un centro de acopio, en donde se acumularán los residuos sólidos urbanos de todo el poblado, se separarán y se tratarán para su futura venta y/o reciclaje. Estudiamos la situación de la bodega en materia de espacios, y realizamos un lay–out (diseño) del acomodo interno, para optimizar de la mejor manera los espacios, movimientos y procesos. Asimismo, se fabricaron prototipo de botes de basura en los que se separaran los residuos; esto se logró realizando una investigación por parte del delegado del pueblo, acordando la mejor ubicación para éstos. Lo anterior se validó mediante herramientas estadísticas y la opinión de un grupo representativo de habitantes de San Isidro. Por último, gestionamos una campaña de limpieza, a manera de concientización de la población, y poner en funcionamiento el centro de acopio.ITESO, A.C

In vivo antimicrobial activity of silver nanoparticles produced via a green chemistry synthesis using Acacia rigidula as a reducing and capping agent

Introduction: One of the main issues in the medical field and clinical practice is the development of novel and effective treatments against infections caused by antibiotic-resistant bacteria. One avenue that has been approached to develop effective antimicrobials is the use of silver nanoparticles (Ag-NPs), since they have been found to exhibit an efficient and wide spectrum of antimicrobial properties. Among the main drawbacks of using Ag-NPs are their potential cytotoxicity against eukaryotic cells and the latent environmental toxicity of their synthesis methods. Therefore, diverse green synthesis methods, which involve the use of environmentally friendly plant extracts as reductive and capping agents, have become attractive to synthesize Ag-NPs that exhibit antimicrobial effects against resistant bacteria at concentrations below toxicity thresholds for eukaryotic cells. Purpose: In this study, we report a green one-pot synthesis method that uses Acacia rigidula extract as a reducing and capping agent, to produce Ag-NPs with applications as therapeutic agents to treat infections in vivo. Materials and methods: The Ag-NPs were characterized using transmission electron microscopy (TEM), high-resolution TEM, selected area electron diffraction, energy-dispersive spectroscopy, ultraviolet–visible, and Fourier transform infrared. Results: We show that Ag-NPs are spherical with a narrow size distribution. The Ag-NPs show antimicrobial activities in vitro against Gram-negative (Escherichia coli, Pseudomonas aeruginosa, and a clinical multidrug-resistant strain of P. aeruginosa) and Gram-positive (Bacillus subtilis) bacteria. Moreover, antimicrobial effects of the Ag-NPs, against a resistant P. aeruginosa clinical strain, were tested in a murine skin infection model. The results demonstrate that the Ag-NPs reported in this work are capable of eradicating pathogenic resistant bacteria in an infection in vivo. In addition, skin, liver, and kidney damage profiles were monitored in the murine infection model, and the results demonstrate that Ag-NPs can be used safely as therapeutic agents in animal models. Conclusion: Together, these results suggest the potential use of Ag-NPs, synthesized by green chemistry methods, as therapeutic agents against infections caused by resistant and nonresistant strains. Keywords: silver nanoparticles, green synthesis, in vitro antibacterial activity, in vivo antibacterial activity, skin infection, toxicological stud

Nitrogen sources on TPOMW valorization through solid state fermentation performed by Yarrowia lipolytica

This manuscript reports the valorization of two-phase olive mill waste (TPOMW) as raw material and carbon source for solid state fermentation using Yarrowia lipolytica as biocatalyst. Due to its chemical characteristics, a combination of different raw materials (TPOMW and wheat bran, WB) was evaluated and two distinct nitrogen sources were applied as supplementation for lipase production. A TPOMW/WB ratio of 1:1 and supplementation with ammonium sulfate was chosen as the best condition. The productivity in 24 h reached 7.8 U/gh and, after four days of process, only decreased about 35%. Process pH ranged from 5.5-5.9, remaining in an acid range. Thus, the successful use of TPOMW, a watery solid by-product with high content of lipids, as raw material for Yarrowia lipolytica growth and lipase production provided an environmental friendly alternative to valorize such waste.The authors kindly acknowledge the financial aid and research scholarships given by CAPES. Maria Alice Zarur Coelho thanks CNPq (Proc. 308890/ 2013-2)

Escucha México: estrategias gráficas y cultura auditiva

El PAP Escucha México está en constante búsqueda de implementar entornos incluyentes, el desarrollo de la educación sobre la salud y cultura auditiva, proveer las herramientas necesarias para un confort acústico e informar a la ciudadanía y a nuestra comunidad universitaria, acerca de la discapacidad auditiva. Con una gran empatía, se busca que la sociedad esté más informada y de este modo, desarrollar una conciencia acerca de las repercusiones que el ruido puede ocasionar, rasgos negativos irreversibles afectando nuestra salud física y emocional. También nos adentramos a conocer términos científicos y logramos adecuar dicha información para transmitirla de manera clara a las demás personas. Para lograr estas metas, el PAP cuenta con 5 proyectos internos con objetivos específicos buscando siempre un entorno incluyente en los que existen diferentes metodologías de trabajo desde cualitativas hasta cuantitativas, e incluso técnicas de investigación y recopilación de datos. Estos proyectos son: Cruzada contra el Ruido, Mariana Anaya Doll, Redes Sociales Escucha México, Cultura Auditiva (Estrategias de Enseñanza/Aprendizaje) y el Segundo Encuentro de Cultura Auditiva. Cada proyecto tiene un propósito en específico, así como diferentes áreas de trabajo que proveen manejo de redes sociales, investigación e incluso apoya a terceros como Mariana Anaya. Parte fundamental como individuos es reconocer nuestro papel dentro de nuestro entorno y por consecuencia, responder de manera correcta a la corresponsabilidad que cada uno de nosotros tenemos en injerencia a actuar de manera responsable en nuestra sociedad. Por ende, estamos comprometidos y abiertos a la apertura de diálogos, información y de nuevas tendencias, para así lograr un mayor alcance con fines educativos y de comunicación con base a la inclusión y el respeto social.ITESO, A.C