Papers by EDGAR REYES CRUZ
Journal of the American Chemical Society, Aug 22, 2022
The Journal of Physical Chemistry Letters
Photoinduced proton-coupled electron transfer and long-range two-proton transport via a Grotthuss... more Photoinduced proton-coupled electron transfer and long-range two-proton transport via a Grotthuss-type mechanism are investigated in a biomimetic construct. The ultrafast, nonequilibrium dynamics are assessed via two-dimensional electronic vibrational spectroscopy, in concert with electrochemical and computational techniques. A lowfrequency mode is identified experimentally and found to promote double proton and electron transfer, supported by recent theoretical simulations of a similar but abbreviated (non-photoactive) system. Excitation frequency peak evolution and center line slope dynamics show direct evidence of strongly coupled nuclear and electronic degrees of freedom, from which we can conclude that the double proton and electron transfer processes are concerted (up to an uncertainty of 24 fs). The nonequilibrium pathway from the photoexcited Franck−Condon region to the E2PT state is characterized by an ∼110 fs time scale. This study and the tools presented herein constitute a new window into hot charge transfer processes involving an electron and multiple protons.
Andamios, Revista de Investigación Social, 2006
Conceptos clave de la vida cotidiana sufren transformaciones en su apropiación debido a los cambi... more Conceptos clave de la vida cotidiana sufren transformaciones en su apropiación debido a los cambios que las NTIC establecen, principalmente la tecnologización y virtualización de espacios privados. De acuerdo con lo anterior, el texto reflexiona acerca de la concepción que se tiene del término realidad partiendo de las coordenadas tiempo y espacio, y realiza un pequeño recuento de los estudios que se han efectuado alrededor de la CMC, con lo que busca eliminar la fragmentación que existe entre realidad y virtualidad. La propuesta es un continuo entre estos términos descrito por el concepto de Realidad Mediada por Computadora (RMC).
Ibersid: revista de sistemas de información y documentación, 2007
Se analiza la productividad científica de los investigadores del Instituto de Investigaciones en ... more Se analiza la productividad científica de los investigadores del Instituto de Investigaciones en Matemáticas Aplicadas y en Sistemas (Mexico), mostrando un panorama de dónde se publica, en que tipo de revistas, así como en qué disciplinas está presente el Instituto, según la clasificación del ISI (Internacional Scientific Institute).
El presente articulo de reflexion se propone aplicar algunas categorias de teoria semiotica perti... more El presente articulo de reflexion se propone aplicar algunas categorias de teoria semiotica pertinentes a la comprension de la interaccion entre el individuo y el entorno objetual. El entorno objetual remite al conjunto potencialmente ilimitado de objetos de uso de cuyas diferencias sutiles y variados tipos, obligan al individuo a ejecutar procesos de interpretacion en los cuales el objeto desempena un papel comunicativo gracias a su naturaleza textual. En esta medida, el objetivo es esclarecer las condiciones iniciales que explican la experiencia interpretativa del objeto de uso como texto.
Se describe un sistema que permite teleoperar un robot a traves de telefonos celulares. Se emplea... more Se describe un sistema que permite teleoperar un robot a traves de telefonos celulares. Se emplea la red de telefonia celular existente en el pais, utilizando el Servicio General de Paquetes por Radiofrecuencia GPRS. De esta manera se permite a los usuarios del sistema un rango mas amplio de movilidad. La implementacion de dichas aplicaciones se hace mediante el lenguaje de programacion JAVA en sus plataformas J2ME para dispositivos moviles y JAVA Servlet para aplicaciones orientadas a servidores. La experiencia se valido con el robot movil Giraa_02 desarrollado en la Universidad de Antioquia.
The Journal of Physical Chemistry Letters, 2020
Understanding and controlling factors that restrict the rates of fuel-forming reactions are essen... more Understanding and controlling factors that restrict the rates of fuel-forming reactions are essential to designing effective catalyst-modified semiconductors for applications in solar-to-fuel technologies. Herein, we describe GaAs semiconductors featuring a polymeric coating that contains cobaloxime-type catalysts for photoelectrochemically powering hydrogen production. The activities of these electrodes (limiting current densities >20 mA cm −2 under 1-sun illumination) enable identification of fundamental performance-limiting bottlenecks encountered at relatively high rates of fuel formation. Experiments conducted under varying bias potential, pH, illumination intensity, and scan rate reveal two distinct mechanisms of photoelectrochemical hydrogen production. At relatively low polarization and pH, the limiting photoactivity is independent of illumination conditions and is attributed to a mechanism involving reduction of substrate protons. At relatively high polarization or pH, the limiting photoactivity shows a linear response to increasing photon flux and is attributed to a mechanism involving reduction of substrate water. This work illustrates the complex interplay between transport of photons, electrons, and chemical substrates in photoelectrosynthetic reactions and highlights diagnostic tools for better understanding these processes.
Photoelectrosynthetic materials provide a bioinspired approach for using the power of the sun to ... more Photoelectrosynthetic materials provide a bioinspired approach for using the power of the sun to produce fuels and other value-added chemical products. However, there remains an incomplete understanding of the operating principles governing their performance and thereby effective methods for their assembly. Herein we report the application of metalloporphyrins, several of which are known to catalyze the hydrogen evolution reaction, in forming surface coatings to assemble hybrid photoelectrosynthetic materials featuring an underlying gallium phosphide (GaP) semiconductor as a light capture and conversion component. The metalloporphyrin reagents used in this work contain a 4-vinylphenyl surface-attachment group at the β-position of the porphyrin ring and a first-row transition metal ion (Fe, Co, Ni, Cu, or Zn) coordinated at the core of the macrocycle. In addition to describing the synthesis, optical, and electrochemical properties of the homogeneous porphyrin complexes, we also report on the photoelectrochemistry of the heterogeneous metalloporphyrin-modified GaP semiconductor electrodes. These hybrid, heterogeneous-homogeneous electrodes are prepared via UV-induced grafting of the homogeneous metalloporphyrin reagents onto the heterogeneous gallium phosphide surfaces. Three-electrode voltammetry measurements performed under controlled lighting conditions enable determination of the open-circuit photovoltages, fill factors, and overall current–voltage responses associated with these composite materials, setting the stage for better understanding charge-transfer and carrier-recombination kinetics at semiconductor|catalyst|liquid interfaces.
ECS Journal of Solid State Science and Technology, 2020
We report on the structural and electrochemical properties of a heterogeneous-homogeneous assembl... more We report on the structural and electrochemical properties of a heterogeneous-homogeneous assembly composed of molecular cobaloxime catalysts immobilized onto graphite electrodes via an intervening polyvinylpyridine surface coating. When these modified electrodes are immersed in an organic solvent (propylene carbonate containing 0.1 M tetrabutylammonium perchlorate as a supporting electrolyte) or basic aqueous solutions (0.1 M NaOH), cyclic voltammetry measurements enable determination of the CoIII/II peak potentials and CoII/I midpoint potentials of cobaloximes embedded within the polymeric architectures. Additionally, voltammetry measurements recorded using pH neutral aqueous solutions (0.1 M phosphate buffer) confirm the immobilized cobaloximes remain catalytically active for hydrogen production and operate at a turnover frequency of 1.6 s−1 when polarized at –0.35 V vs the H+/H2 equilibrium potential. Waveform analysis of redox features associated with immobilized cobaloximes in...
Journal of the American Chemical Society, 2019
Additional Information on Experimental Methods Materials Zn-doped p-type GaP(100) wafers were pur... more Additional Information on Experimental Methods Materials Zn-doped p-type GaP(100) wafers were purchased from ITME. The single-side-polished, crystalline wafers had a 400 μm thickness, a resistivity of 0.053-0.045 Ω cm, a carrier concentration of 1.8-2.3 × 10 18 cm −3 , and an etch pit density of less than 2 × 10 4 cm −2. Sample Preparation Diced semiconductor samples were degreased by wiping the surface with an acetone-soaked cotton swab and ultrasonically cleaning in acetone and isopropanol for 5 min each, followed by drying under nitrogen. Samples were then exposed to an air-generated oxygen plasma (Harrick Plasma, U.S.) at 30 W for 2 min. Surface oxide layers were then removed by immersion of the plasma-treated samples in buffered hydrofluoric acid (6:1 HF/NH4F in H2O) for 5 min, followed by rinsing with distilled methanol. Freshly etched wafers were put into an argon-sparged solution of the neat monomer 4-vinylpyridine and exposed to 254 nm UV light for 2 h. After thoroughly rinsing with methanol the wafers were dried under nitrogen and stored under vacuum. The PPy-functionalized samples were then soaked for 18 h in a cobalt (II) 5,10,15,20-tetra-ptolylporphyrin solution (1 mM) in toluene. We note that the GaP ingot used to prepare the samples described in this report has different physical characteristics (doping density, charge mobility, and resistance) than those previously reported. 1-6 For the porphyrin-modified electrodes assembled from these wafers, the polypyridine coatings are 3.8 ± 1.4 nm thick as measured by spectroscopic ellipsometry. With 25% of the pyridyl sites coordinated to a cobalt center, 1 the per geometric area surface concentration of cobalt is approximately 1 nmol cm-2. GaP working electrodes were fabricated by applying an indium−gallium eutectic (Aldrich) to the backside of a wafer, then fixing a copper wire to the back of the wafer using a conductive silver epoxy (Circuit Works). The copper wire was passed through a glass tube, and the wafer was insulated and attached to the glass tube with Loctite 615 Hysol Epoxi-patch adhesive. The epoxy was allowed to fully cure (approximately 24 h) before testing the electrodes. UV-Vis-NIR Optical measurements were performed on 400 μm thick gallium phosphide wafers. The transmittance and reflectance of GaP samples were measured using a SolidSpec-3700 UV-VIS-NIR spectrophotometer (Shimadzu, Kyoto, Japan) equipped with an integrating sphere. The baseline for reflectance measurements was collected with a STAN-SSH-reference mirror (OceanOptics).
SSRN Electronic Journal, 2018
In the second half of the twenty century we observe two important patterns of structural change; ... more In the second half of the twenty century we observe two important patterns of structural change; …rst, a large shift of employment from the agriculture and manufacturing sectors to the service sector, and, second, an increase in leisure time. We relate these two patterns of structural change by arguing that during leisure time we consume recreational services. The observed increase in leisure time then implies an increase in the consumption of these services, which introduces a new mechanism of structural change. In order to measure the impact of this mechanism, we construct a multi-sector exogenous growth model with biased technological change. The new feature of the model is the introduction of recreational activities, which depend on both leisure time and on the consumption of recreational services. We introduce these activities by assuming a non-homothetic nested CES utility function. The model explains the two patterns of structural change. We also show that the introduction of these activities improves the performance of the numerical simulations. We conclude that the increase in recreational activities is an important feature of structural change. JEL classi…cation codes: O41, O47.
ACS Catalysis, 2018
Binuclear copper(II) porphyrins in which two copper(II) porphyrin macrocycles are doubly fused at... more Binuclear copper(II) porphyrins in which two copper(II) porphyrin macrocycles are doubly fused at the mesobeta positions are shown to be active electrocatalysts for the hydrogen evolution reaction (2H + + 2e-à H2). Structural characterization, including use of electron paramagnetic resonance and x-ray photoelectron spectroscopies, verifies the fused species contains two copper(II) metal centers in its resting state. In comparison to the non-fused copper(II) porphyrin complex, the fused species is reduced at significantly less applied bias potentials (ΔE½ ~ 570 mV for the first reduction process). Electrochemical characterization in the presence of substrate protons confirms the production of hydrogen with near-unity Faradaic efficiency, and kinetic analysis shows the catalyst achieves a maximum turnover frequency above 2,000,000 s-1. The enhancement in catalytic performance over analogous non-fused copper(II) porphyrins indicates extended macrocycles provide a structural motif and design element for preparing electrocatalysts that activate small molecules consequence to renewable energy.
PloS one, 2018
Pancreatic Autoimmunity is defined as the presence of autoantibodies and more frequent need for i... more Pancreatic Autoimmunity is defined as the presence of autoantibodies and more frequent need for insulin treatment. Affected women presenting recurrent implantation failure (RIF) or recurrent miscarriage (RM) are often misdiagnosed. The objective of thestudy was to describe clinical and metabolic profiles suggestive of Pancreatic Autoimmunity and therapeutic strategy in patients with RIF/RM. We analyzed retrospectively 735 patients, and have identified a subset (N = 20) with similar metabolic characteristics. At the same time, we included a control group (n = 39), with similar demographic characteristics and negative for pancreatic, thyroid or celiac disease autoimmunity. The patients identified with autoimmune metabolic problem (N = 20) had relatives with diabetes mellitus. At 120 minutes after Oral Glucose Tolerance Test (OGTT) low level of insulin secretion (<2 IU/ml) was found in 70% of patients. Glutamic acid decarboxylase 65 (GAD 65) antibodies, with or without other autoant...
Biochemical and biophysical research communications, Jun 13, 2018
Chlamydia trachomatis entry into host cells is mediated by pathogen-directed remodeling of the ac... more Chlamydia trachomatis entry into host cells is mediated by pathogen-directed remodeling of the actin cytoskeleton. The chlamydial type III secreted effector, translocated actin recruiting phosphoprotein (Tarp), has been implicated in the recruitment of actin to the site of internalization. Tarp harbors G-actin binding and proline rich domains required for Tarp-mediated actin nucleation as well as unique F-actin binding domains implicated in the formation of actin bundles. Little is known about the mechanical properties of actin bundles generated by Tarp or the mechanism by which Tarp mediates actin bundle formation. In order to characterize the actin bundles and elucidate the role of different Tarp domains in the bundling process, purified Tarp effectors and Tarp truncation mutants were analyzed using Total Internal Reflection Fluorescence (TIRF) microscopy. Our data indicate that Tarp mediated actin bundling is independent of actin nucleation and the F-actin binding domains are suf...
Scientific reports, Apr 7, 2017
TGF-β1 is the main mediator of epithelial-to-mesenchymal transition (EMT). Hyperoxaluria induces ... more TGF-β1 is the main mediator of epithelial-to-mesenchymal transition (EMT). Hyperoxaluria induces crystalluria, interstitial fibrosis, and progressive renal failure. This study analyzed whether hyperoxaluria is associated with TGF-β1 production and kidney fibrosis in mice and if oxalate or calcium oxalate (CaOx) could induce EMT in proximal tubule cells (HK2) and therefore contribute to the fibrotic process. Hyperoxaluria was induced by adding hydroxyproline and ethylene glycol to the mice's drinking water for up to 60 days. Renal function and oxalate and urinary crystals were evaluated. Kidney collagen production and TGF-β1 expression were assessed. EMT was analyzed in vitro according to TGF-β1 production, phenotypic characterization, invasion, cell migration, gene and protein expression of epithelial and mesenchymal markers. Hyperoxaluric mice showed a decrease in renal function and an increase in CaOx crystals and Ox urinary excretion. The deposition of collagen in the renal i...
Mobile DNA, 2016
Background: The genomic data available nowadays has enabled the study of repetitive sequences and... more Background: The genomic data available nowadays has enabled the study of repetitive sequences and their relationship to viruses. Among them, long terminal repeat retrotransposons (LTR-RTs) are the largest component of most plant genomes, the Gypsy and Copia superfamilies being the most common. Recently it has been found that Del lineage, an LTR-RT of Gypsy superfamily, has putative virus-like attachment (vl-att) sites. This signature, originally described for retroviruses, is recognized by retroviral integrase conferring specificity to the integration process. Results: Here we retrieved 26,092 putative complete LTR-RTs from 10 lineages found in 10 fully sequenced angiosperm genomes and found putative vl-att sites that are a conserved structural landmark across these genomes. Furthermore, we reveal that each plant genome has a distinguishable LTR-RT lineage amplification pattern that could be related to the vl-att sites diversity. We used these patterns to generate a specific quickresponse (QR) code for each genome that could be used as a barcode of identification of plants in the future. Conclusions: The universal distribution of vl-att sites represents a new structural feature common to plant LTR-RTs and retroviruses. This is an important finding that expands the information about the structural similarity between LTR-RT and retroviruses. We speculate that the sequence diversity of vl-att sites could be important for the life cycle of retrotransposons, as it was shown for retroviruses. All the structural vl-att site signatures are strong candidates for further functional studies. Moreover, this is the first identification of specific LTR-RT content and their amplification patterns in a large dataset of LTR-RT lineages and angiosperm genomes. These distribution patterns could be used in the future with biotechnological identification purposes.
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Papers by EDGAR REYES CRUZ