Daniel Hernandez cruz

• PhD in Physics, MSc. in opctis, Electronic Engineer
• Professor at Autonomous University of Chiapas

Este libro fue desarrollado, a partir de resultados, procesos, experiencias y reflexiones de la etapa 1, por miembros del Proyecto de Investigación e Incidencia (PRONAII), denominado “Desarrollo de un modelo de producción social replicable de vivienda y hábitat” de número 321260 de la “Convocatoria 2022 Proyectos Nacionales de Investigación e Incid...

The application of hydroxyapatite (HAp)/multi-walled carbon nanotube composites in the medical area as coatings in prosthetics has been widely used because the carbon nanotubes reinforce the mechanical properties of hydroxyapatite. Despite that, their photoluminescent properties have not been studied, nor has the effect of different amounts of mult...

The performance of the influence of cane bagasse ash (CBC) as filler in self-compacting concrete mixtures (CAC), added in a 0%, 5%, 10%, 15%, 20% and 25% with respect to weight of cement was evaluated. Ash characterization was performed by FTIR, FRX and XRD. The workability properties of CAC were determined by slump flow, J-ring, L-box, V-funnel, V...

En la presente colaboración damos a conocer los materiales utilizados para la construcción de viviendas (desde la cimentación hasta la cu¬bierta) los cuales deben cumplir con características, físicas químicas y mecánicas si son utilizados como sistema estructural, sobre todo si se encuentra en zonas sísmicas. El objetivo de este trabajo es realizar...

RESUMEN Se evaluó el riesgo por corrosión del acero en concreto, utilizando sensores galvánicos internos de acero al carbono/acero inoxidable y un electrodo externo de Cu/CuSO4. Los sensores se utilizaron para monitorear los potenciales y corrientes de macrocelda de probetas prismáticas de concreto reforzado con relaciones agua-cemento de 0.4 y 0.6...

Hydroxyapatite (HAp) and hydroxyapatite/multi-walled carbon nanotube (MWCNT) composites were obtained by the co-precipitation method, followed by ultrasound-assisted and microwave radiation and thermal treatment at 250 °C. X-ray diffraction (XRD) confirmed the presence of a hexagonal phase in all the samples, while Fourier-transform infrared (FTIR)...

The incorporation of crushed glass as a substitute for natural aggregates in mortar and concrete represents a positive impact on the manufacturing processes. The use of glass residues can lead to the improvement of certain properties of sustainable construction products. In these cases, it is important to analyse in detail the behaviour of the mate...

El presente trabajo se estructura en cuatro partes; la primera se centra en la descripción de los agregados usados en la elaboración de los morteros tipo estuco, una breve descripción de la historia de los cementantes, así mismo del problema que representa su elaboración sin materiales reciclados y la alternativa presentada, el vidrio pulverizado....

We present a simple but accurate correlation between an experimental characterization and a simple analytical prediction of a wave propagation induced by the impact of a pendulum in a box filled with fine sand; this research is based on optical measurements and was carried out using the digital image correlation technique to determine the motion on...

This work presents the hydrologic estimations of the hydraulic underground arched culvert channel (UACC) in Sabinal Basin, Chiapas, México and the hydrological problems associated with it, such as the erosion phenomenon and abrasion cavity formation in it. On the other hand, the maximum flows that the UACC could transport were analyzed, concluding...

La producción de vidrio en México fue de 15 mil millones de unidades en 2014 (Ramírez, 2015). Aunque un alto porcentaje es para exportación, otro tanto, se queda en el país. En consecuencia, el vidrio de desecho contribuye con 6% a la generación de basura (SEMARNAT, 2012) y necesita ser reciclado. Este trabajo presenta comportamiento a la carbonata...

El río Sabinal atraviesa, de poniente a oriente, la ciudad de Tuxtla Gutiérrez, Chiapas, con una longitud aproximada de 12 km. Este río tiene 21 afluentes y con el paso de los años y el crecimiento poblacional, la zona federal del río y sus afluentes fue invadido por la mancha urbana. Actualmente cuatro afluentes embovedados representan un alto rie...

RESUMEN En este artículo, se propone el empleo de vidrio reciclado y molido de tonalidades blanca y ámbar como reemplazo de agregado fino en mortero base cemento portland, con porcentajes del 10%, 15% y 20%, y con una relación agua-cemento de 0.53. Se analiza el comportamiento mecánico de probetas, mediante pruebas de resistencia a la compresión. A...

Most public universities in Latin America and Mexico lack laboratories formeasuring sediment transport or to do academic activities. The ResearchCenter of the engineering faculty of Chiapas state university (UNACH by itsacronym in Spanish) designed a portable prismatic channel for teaching andresearching the sediment transportation in rivers. This...

This document presents the technical description and cost comparison of four rainwater harvesting systems for homes, the method for its hydraulic de-sign and an equation to estimate the minimum catchment area, with the goal to supply drinking water to segregated small communities in Mexico consi-dering climatechange effects, both natural and anthro...

The understanding and control of early hydration of tricalcium silicate (C3S) is of great importance to cement science and concrete technology. However, traditional characterization methods are incapable of providing morphological and spectroscopic information about in situ hydration at the nanoscale. Using soft X-ray spectromicroscopy, we report t...

El túnel de avenamiento de San Cristóbal las Casas, Chiapas se construyó hace más de 40 años, por el circulan no solo el agua de lluvia que la cuenca endorreica desfoga en la época de lluvias, sino también las agua negras de dicha ciudad, por lo tanto está permanentemente sometido a la humedad y los gases corrosivos que se desprenden de éstas aguas...

Alkali-Silica reaction (ASR) is a physicochemical process that can deteriorate concrete and is a recurring engineering problem. In this study three different cylindrical samples affected by ASR were prepared: a plain mortar and two composite mortars containing fibers (polypropylene and a polymer hybrid), which were analyzed at the microtomography (...

This paper investigates the atomic and nano-scale structures of a 50-year-old hydrated alite paste. Imaged by TEM, the outer product C-S-H fibers are composed of particles that are 1.5-2 nm thick and several tens of nanometers long. 29Si NMR shows 47.9% Q1 and 52.1% Q2, with a mean SiO4 tetrahedron chain length (MCL) of 4.18, indicating a limited d...

Calcium silicate hydrates (C-S-H), the primary binding phase in concrete, is the most prominent physiochemical factor controlling the mechanical and chemical properties in the production of concrete. This paper reports the local-binding structure and morphological details of C-S-H as determined by high-resolution X-ray spectromicroscopy. Hydrated t...

ABSTRACTThe goal of this paper is to present the most common characteristics of heavy machi-nery used for construction process. Also, the basic factors that affect the machinery efficiency and performance in order to achieve low cost operations. These obser-vations come as a result of many conduc-ted tests by specialists as well as conside-ring the...

Candida biofilms are a major cause of mortality in immunocompromised and immunosuppressed patients.

En México, el suministro de agua a pequeñas comunidades rurales es un problema no resuelto. Diversas fuentes reportan que en zonas rurales existen más de 5.7 millones de mexicanos que carecen de agua entubada y 12 millones en todo el territorio nacional. Solo en el estado de Chiapas existen alrededor de 18,160 pequeñas comunidades rurales menores d...

La industria del cemento es una de las que menos se pueden considerar sustentables, por la contaminación que causa durante el proceso de fabricación. Sin embargo, estudios actuales permiten conocer los procesos químicos que se llevan a cabo durante la mezcla del cemento con agua, agregados, aditivos, etc., lo cual contribuye a entender mejor dicha...

We are reporting the fabrication of a very efficient electron source using long and crystalline carbon nanotubes. These devices start to emit electrons at fields as low as 0.10 V/μm and reach threshold emission at 0.164 V/μm. In addition, these electron sources are very stable for long operation periods up to 200 hrs and can achieve peak current de...

We are reporting the fabrication of a very efficient electron source using millimeter-long and highly crystalline carbon nanotubes. These devices start to emit electrons at fields as low as 0.17 V/μm and reach threshold emission at 0.24 V/μm. In addition, these electron sources are very stable and can achieve a peak current density of 750 mA cm(-2)...

We prepare optrodes of fiber optic plastic with sol-gel technique. Suitable concentration of carbone nanotubes (CNTs), phenol red, bromophenol blue and cresol red, design optrodes with fiber optic plastic. The surface charge of silica and the refractive index, which play an important roll on the fiber, modifies the conditions of light propagation i...

We have used the recently completed soft X-ray spectromicroscopy facility at the Canadian Light Source (CLS) to study individual multi-walled carbon nanotubes (MWCNTs) with scanning transmission X-ray microscopy (STXM). Specifically, spatially resolved C 1s X-ray absorption linear dichroism signals were used to map structural defects. The STXM on C...

The alignment of β-sheets within spider dragline silk fibers is an important factor in their tensile strength and extensibility. We are using linear dichroism of the C 1s → π*amide transition measured using scanning transmission X-ray microscopy (STXM) to generate quantitative maps of the orientation parameters with 30 nm spatial resolution. Here w...

We present a combined study by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and scanning transmission X-ray microscopy (STXM) of the successful formation of nanocomposites of polypropylene with montmorillonite by melt processing, providing a complete picture of the intercalation and exfoliation proc...

The nature of organic species associated with clay minerals plays a significant role in several processes, from hydrocarbon recovery in oil sands to contaminated soil remediation and water treatment. In this work, we address the use of scanning transmission X-ray microscopy (STXM) in conjunction with near edge X-ray absorption fine structure (NEXAF...

Nonlinear effects are consequence of interaction of height intensities of energy with the matter. Self-diffraction is nonlinear effect and rings are produced. We analyzed the increase of rings due to changes in intensity of CW Ar laser that modify the nonlinear refractive index. The Carbon Nanotubes (CNTs) were dispersed on different solvents: a) w...

Carbon nanostructrures, especially carbon nanotubes (CNTs), have shown applications on different areas of science and technology. For example, in photonics, due to their diversity in morphology (size, form, and structure) and properties of CNTs, research has focused mainly on single wall nanotubes (SWNT) leaving the multi walled nanotubes (MWNT) as...

Carbon nanotubes (CNT’s) have been used in different areas to improve intrinsic properties of materials. During last years, non linear optical properties have been studied on different novel materials mainly organic but now, nanoparticles and nanotubes (mostly single wall - SWNT) have found very good applications in photonics. One of the common app...

The polarization dependence (linear dichroism) of the C 1s X-ray absorption spectrum of individual multi-walled carbon nanotubes (MWCNTs) is measured using scanning transmission X-ray microscopy. A very strong dichroic effect is found in the C 1s --> pi* transition, with almost complete disappearance of this transition when the electric-field (E)-v...

Over the last few years there has been an increasing interest in Carbon Nanotubes (CNTs) both for electronic and photonics applications. From the photonics perspective, the fact that CNTs act as saturable absorbers with ultrafast recovery makes them an ideal material for the realization of passive mode-locking laser [1]. There are a couple of works...

In the last 20 years, synchrotron based soft X-ray scanning transmission X-ray microscopy (STXM) [1,2] has emerged as a powerful micro-analytical technique with particular strengths in the analysis of soft matter — polymers, biological and environmental samples. Its analytical power stems from spatially resolved near-edge X-ray absorption spectrosc...

Scanning transmission X-ray microscopy (STXM) has been used to probe the electronic structure of individual multiwall carbon nanotubes by chemical mapping at the nanoscale. Carbon 1s near-edge X-ray absorption fine structure (NEXAFS) spectra of individual structures are shown to be able to differentiate carbon nanotubes from onionlike carbon nanopa...

The intrinsic variation in the near-edge X-ray absorption fine structure (NEXAFS) spectra of peptides and proteins provide an opportunity to identify and map them in various biological environments, without additional labeling. In principle, with sufficiently accurate spectra, peptides (<50 amino acids) or proteins with unusual sequences (e.g., cys...

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Nephila clavipes dragline silk microstructure has been investigated by scanning transmission X-ray microscopy (STXM), a technique that allows quantitative mapping of the level of orientation of the peptide groups at high spatial resolution (<50 nm). Maps of the orientation parameter P2 have been derived for spider silk for the first time. Dragline...

A novel miniature rotation device used in conjunction with a scanning transmission x-ray microscope is described. It provides convenient in situ sample rotation to enable measurements of linear dichroism at high spatial resolution. The design, fabrication, and mechanical characterization are presented. This device has been used to generate quantita...

Scanning transmission x-ray microscopy (STXM) has been used to study isolated carbon nanotubes for the first time. STXM and transmission electron microscopy were applied to the same type of nanotubes, providing unique information about their composition, and electronic and structural properties. The carbon 1s near-edge x-ray absorption fine structu...

of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois, USA, July 30 – August 3, 2005

The spatial distribution of the linear dichroic signal associated with aligned beta-sheets in a microtomed section of a Bombyx mori cocoon silk fiber was derived from scanning transmission X-ray microscopy (STXM). The intense C 1s --> pi(amide) peak at 288.25 eV was found to have negligible dichroic signal in transverse sections but a large dichroi...

In this paper, design and characterization of a pH optical fiber sensor with pH sensitive dye is described. The sensor is prepared by fixing the doped plastic fiber on a fused ortosilica block surface with blue bromophenol. The surface charge of silica and the refractive index, which plays an important roll on the fiber, modifies the conditions of...

Design and characterization of a pH optical fiber sensor with a pH sensitive dye is described in this paper. TEOS (Tetra-ethyl-Orto-Silicate) was used to dope a plastic optical fiber, which will be used as the optical probe (OPTRODE). The sensor is prepared by fixing the doped plastic fiber on a fused ortosilica block surface with blue bromophenol....

Typical characteristics of BaTiO3 thin films, such as hysterisis behavior, spontaneous polarization below the Curie temperature, faster switching speed, etc., are particularly of interest for high capacitance integrated elements, dynamic random access memories (DRAMs), phase conjugation, holographic optical data storage, two-beam coupling, optical...

Typical characteristics of BaTiO3 thin films, such as hysterisis behavior, spontaneous polarization below the Curie temperature, faster switching speed etc., are particularly of much attention for high capacitance integrated elements, dynamic random access memories (DRAMs), phase conjugation, holographic optical data storage, two-beam coupling and...

The modification of thin Teflon AFTM films by He+ ion irradiation was investigated. As an integrated optical measurement technique, leaky-mode spectroscopy has been applied, and an increase of (Delta) n equals 8 X 10-3 for the real part of the refractive index has been found in the irradiated surface region of the film. The irradiated films can be...

We report the synthesis of polycrystalline barium titanate BaTiO3 thin films on silicon substrate prepared by sol- gel technique. The structure and composition of ferroelectric film ms have been analyzed by using x-ray photoelectron spectroscopy and Rutherford backscattering spectroscopy. These methods provide information on the core level electron...

The characteristics of thin BaTiO3 films deposited on Si and MgO substrates by employing the metal-organic deposition technique are studied. In the experiment, the commercial barium 2-ethyihexanoate and the synthesized titanium dimethoxy dineodecanoate are used as precursors for the formation of BaTiO3 films. The film characterization is performed...

Linear detection of the optical phase modulation in a randomly polarized laser beam is highly important, in particular, for optical fiber sensors and coherent optical communication systems. This type of detection cannot be performed properly by means of conventional techniques, and the problem is that the original optical signal beam has, in genera...