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This study shows the 222Rn concentration levels registered in 45 wells of the federal water supply system of Mexico City. Mexico City is one of the most populated cities in the world and has considerable telluric activity. Despite these two facts, there are no studies that analyze radon concentration levels in water supplied by the government. The values obtained show a concentration that ranges between 0.11 and 2.4 Bq L−1, levels below those recommended by the World Health Organization.

Fused Deposition Modelling (FDM) is a powerful method for advanced additive manufacturing of polymeric materials, due to its simplicity and low cost. However, the process implies complex phenomena which are not fully understood yet. In particular, the effect of viscosity on the printed thread is a key parameter to control if good quality products are to be obtained. Experimental data of two grades of acrylonitrile-butadiene- styrene copolymer (ABS) was employed to analyse, by using ANSYS Fluent simulation package, six printing velocities at a temperature of 230°C. A drastic temperature change was observed as the printing velocity increases, confirming the effect of viscosity on the shear created on the wall of the nozzle transversal to the printing bed. The polymers analysed present different viscosity behavior even under the same angular frequency range (0.1 to 100 rad/s), and testing temperature (230°C), which could lead to inhomogeneities. Our results allow taking into account these parameters as part of the design criteria.

The “measuring device” is one of the most reliable, efficient and economic indoor radon dosimeters that exist. This device was developed by the Proyecto de Aplicaciones de la Dosimetría (PAD) at the Physics Institute of UNAM (IF-UNAM) and consists of a transparent rigid plastic cup, a CR-39 polycarbonate sheet and a standard size metal clip that is used to hold the polycarbonate in the center of the cup. The cup is wrapped and covered with a low-density polyurethane protector in order to prevent the detector from being irradiated by ionizing particles found in the environment. In this work, an analysis was carried out that allowed to understand how the radon concentration on the polycarbonate sheet varies when its height is changed with respect to the base of the plastic cup, in order to understand what position increase the probability of interaction between radon and the surface of the detector. For the development of this work, four computational simulations were performed with the technique called Computational Fluid Dynamics (CFD). The results shows that as the CR-39 is positioned more closed to the base of the cup, the probability of interaction of the radon and the detector increase. Based on these results it is concluded that, when there is a limit in the time in which a measuring device can be placed in the zone where it is desired to quantify indoor radon, it is recommended to collocated the CR-39 at 1 cm with respect to the base of the cup.

Au and Ag nanoparticles (NP) were synthesized using a green method that allows control of both particle size and surface chemistry. The gold and silver nanoparticles were coated with a fluorescent goat anti-body IgG that chemically incorporated the nanoparticles and the internalization behavior was studied by phagocytosis in murine peritoneal macrophages. Despite that, in principle, the presence of a simple metal induces a greater degree of cell death following the particle uptake, our results suggest that a large part of the silver and gold nanoparticles enter cells by means other than endocytosis and phagocytosis, as truly intelligent nanoparticles. This represents a potential for immunotherapy and studies to modulate the innate immune response as truly smart nanoparticles.

Novel silica aerogels were produced from carbon nanotubes/carbon black/polypyrrole (NTC/CB/PPy) blends, and their structure characterized by FT-IR analysis. X-ray diffraction analysis confirms the presence of amorphous silica and a new reflection at 2θ = 13°, which had not been reported before. SEM micrographs of the aerogels reveal the connectivity of the micropores of the material, along with the different fillers (NTC/CB/PPy), which allow to increase the water absorption of the aerogels and to increase thermal stability. The mechanical and thermal properties of the resulting aerogels are significantly better than those of similar materials reported in the literature.

Radon gas is recognized by international organizations such as the United States Environmental Protection Agency (US-EPA) as the main contributor of radiation environmental to which human beings are exposed. Therefore, the evaluation of indoor radon concentration is a matter of public interest. The emanation and the income of the gas inside a room will generate a negative impact on the quality of the air when the place is not properly ventilated. Understanding how this gas will be distributed inside the room will allow to predict the spatial and temporal variations of radon levels and identify these parameters will provide important information that researchers can be used for calculate radiation dose exposure. Consequently, this studies can prevent a health risk for the people that live or work within the room. Currently, several researchers use the technique called Computational Fluid Dynamics (CFD) to simulate the distribution of gas radon, making use of the various commercial programs that exist in the market. In this work, three simulations were developed in rooms that have a similar geometry but different dimensions, in order to observe how the gas is distributed inside a closed space and to analyze how this distribution varies when the volume of the place is increased. The results show that as the volume of the site increases the radon is mitigated more rapidly and therefore has lower levels of concentration of this gas, as long as the level of radon emanation is kept constant.

A design and principle of silicon photodiodes (PD) operation in the frequency domain are presented. To further enhance the signal-to-noise ratio, a methodology is proposed regarding how to cut down the response in the frequency domain between the time constant and stability characteristics. An algebraic-analytic model is developed to obtain the frequency behavior of the PD which are used as semiconductor devices to capture optical modulated light. The proposed model consists of connecting the anode and cathode terminals of a PD, an operational amplifier (AOP) for performing a control over the frequency domain optical device. The basic idea consists in analyzing the response of the PD at different frequencies using Bode, Nyquist and Black diagrams which have been obtained by a transfer function in the frequency domain when the optical response is attenuated. Consequently, a cutoff frequency to be determined by a test signal, and thus allowing for a certain range of frequency capture for operation and application of the PD. This paper highlights several key issues in the measurement methods on frequency domain of the Si PD. In some cases, indirect signal metering of modulated light presents unwanted signals. Consequently, the RC filter responses they are frequency filtering effect. Therefore, for the improved PD measurements, might be necessary the solution in the frequency domain for transfer function and theoretical-experimental relationship on materials testing. The results show that this system has the capacity to acquire the operating range in the frequency domain and thereby calculate the cutoff frequency through the solution of the real and imaginary part of the PD-AOP transfer function model.

Accelerated degradation tests (ADT) are widely used in the manufacturing industry to obtain information on the reliability of components and materials, by degrading the lifespan of the product by applying an acceleration factor that damage to the material. The main objective is to obtain fast information which is modeled to estimate the characteristics of the material life under normal conditions of use and to save time and expenses. The purpose of this work is to estimate the lifespan distribution of gold nanoparticles stabilized with lipoic acid (GNPs@LA) through accelerated degradation tests applying sodium chloride (NaCl) as an acceleration factor. For this, the synthesis of GNPs@LA was carried out, a constant stress ADT (CSADT) was applied, and the non-linear Wiener process was proposed with random effects, error measures, and different covariability for the adjustment of the degradation signals. The information obtained with the test and analysis allows us to obtain the life distribution in GNPs@LA, the results make it possible to determine the guaranteed time for possible commercialization and successful application based on the stability of the material. In addition, for the evaluation and selection of the model, the Akaike and Bootstrapping criteria were used.

Using the colloidal method, and lipoic acid as a stabilizer, ultrasmall gold nanoparticles with an average size of 2.5 nm were synthesized. They are highly stable, have COOH functional groups, at concentrations lower than 100 μg/mL are non-cytotoxic, and the synthesis route is simple and economical. UV–Vis, FT-IR, Raman, and TEM spectroscopy were used to analyze their stability, composition and morphology. Furthermore, the cytotoxicity of the gold nanoparticles was evaluated by MTT assay.

The traditional method for the estimation of soil loss by croplands erosion is the measurement through erosion pins, which consists of stakes with a specified height distributed across the land area; however, this method is inaccurate to measure the soil depth. In some cases, a simple description of the 3D and depth map scenarios is useful to understand the problem. In this study I introduced an instrument of three-dimensional measurement with a camera and a laser to extract the information from the soil depth. Then, a structural mesh in 3D from the scene is obtained and this information is processed in order to estimate the soil loss. The retrieved depth depends on the dynamic relationships among the objects in the scene and the instrument control; this device can adapt to the graphics and dimensions of the surface under study. Here I show the generation of a depth map from a mesh with third order polynomials. This mesh describes the behavior of the surface where full panoramic integration is performed by using multiple partial views of object. The results show that this system has the capacity to acquire soil erosion information; in addition, other parameters can be obtained such as visual information of texture, size perspective, and shadows edges. In this work the vision system covered an area of 1.20 m long by 0.8 m wide. This laser device offered depth analysis and topology from the soil using computer vision through empirical Kostiakov-Lewis models.

The adsorption capacities for the removal of hexavalent chromium from aqueous solutions by six carbon nanomaterials have been evaluated. Single-walled and multi-walled carbon nanotubes as received and after oxidation treatment, graphene oxide and reduced graphene oxide are the materials with different dimension and functionalization compared in this research. Carbon nanotubes have been modified using hydrogen peroxide as oxidizing agent under microwave radiation. The oxidation treatment on carbon nanotubes has a positive effect increasing the adsorbent–adsorbate interaction. Rate-controlling mechanisms and equilibrium data are analyzed using non-linear models. Non-linear method is proposed as the most suitable method for determining the kinetic and equilibrium parameters. The values of adsorption energy (E) obtained from the Dubinin–Radushkevich isotherm, have been found around 0.371 and 0.870 kJ·mol−1, indicating physical adsorption. Therefore, the pseudo-second order model represents better the kinetic experimental data. The results show that the Langmuir isotherm provides a slightly better fit to the experimental data compared with the Freundlich isotherm, indicating homogeneous distribution of active sites on carbon nanomaterials and monolayer adsorption. The separation factors RL are found in the range of 0–1, suggesting that the adsorption process is suitable for all adsorbents. The mechanisms for hexavalent chromium removal have been proposed as electrostatic interactions and hydrogen bonding.

The electrical response of dye-based photovoltaic cells upon a sudden illumination is explained in terms of a theoretical approach based on a time-hierarchical emergence of several physical processes. Our approach ensures the coupling the four main processes that take place, namely, the photochemical activation of the cell, the electrical current associated with electron transport, the relaxation of the polarization due to the motion of ions and, finally, the elastic–osmotic effect that produces rapid oscillations in the output photocurrent of the cell when is suddenly illuminated. The model shows that mordants control/modify three relaxation times: the characteristic time of the photochemical activation due to a partial light-blocking, the characteristic time for the electrical current associated with the electron transport due to mordant adsorption into the mesoporous surface, and the polarization relaxation due to a change in the ions transported to the electrodes. The model fits with high-precision the experimental data of the photo-induced current showing highly non-linear time-dependent oscillations.

Different strategies are reported in the literature for energy saving in Closed Plant Production Systems (CPPS). However, not reliable evidences about energy consumption with the use of pulsed LED light technique in lighting system available in Plant Factory and Vertical Farm. In this work, three key points to determine the effects of pulsed LED light versus continuous LED light are presented: (1) A mathematical model and its practical application for stabilizing the energy equivalence using LED light in continuous and pulsed mode in different light treatments. (2) The quantum efficiency of the photosystem II was used to determine positive and/or negative effects of the light operating mode (continuous or pulsed) on chili pepper plants (Capsicum annuum var. Serrano). (3) Evaluation of energy consumption with both operation modes using ten recipes from the literature to grow plants applied in Closed Plant Production Systems, different Photosynthetic Photon Flux Density at 50, 110, and 180 µmol m−2 s−1, Frequencies at 100, 500, and 1000 Hz, and Duty Cycles of 40, 50, 60, 70, 80, and 90%. The results show no significant statistical differences between the operation modes (continuous and pulsed LED light). For each light recipe analyzed, a pulsed frequency and a duty cycle were obtained, achieving significant energy savings in every light intensity. The results can be useful guide for real-life applications in CPPS.

Selecting a desired level of quality in a product is crucial—for instance, in dried chili peppers (Capsicum annuum L.). However, classifying dried chili peppers is a time-consuming, manual task. One of the main problems with sorting this way is the lack of product homogeneity. This paper presents the development of a classification system, based on artificial neural networks, for size and color recognition applied to the aforementioned peppers. The classification system uses 8-bit grayscale-image histograms to characterize the peppers. Three quality levels identified in a Mexican Official Norm (NMX-FF-107/1-SCFI-2014) for a specific type of chili (Guajillo) were used to show the proposed method. The effectiveness of the proposed classification system is demonstrated through experiments and is measured using the receiver-operating characteristic curve, calculating the area under the curve and obtaining an accuracy of 82.13. The results show an innovative, reliable and economical alternative, capable of sorting dried chili peppers; a system that aims to contribute to the solution of the problem of identification and classification in dehydrators y/o final customers.

The article speaks about the need for training within the company; the company’s role in the provision of training; the measurement of training (its success, etc.); what its role is in training provision; and what might be the evolution of its training commitment after its provision has been established.

The determination of the adequate time for house confinement and when social distancing restrictions should end are now two of the main challenges that any country has to face in an effective battle against. The possibility of a new outbreak of the pandemic and how to avoid it is, nowadays, one of the primary objectives of epidemiological research. In this work, we go deep in this subject by presenting an innovative compartmental model, that explicitly introduces the number of active cases, and employing it as a conceptual tool to explore the possible fates of the dispersion of SARS-COV-2 in the Mexican context. We incorporated the impact of starting, inattention, and end of restrictive social policies on the time evolution of the pandemics via time-in-run corrections to the infection rates. The magnitude and impact on the epidemic due to post-social restrictive policies are also studied. The scenarios generated by the model can help authorities to determine an adequate time and population load that may be allowed to reassume normal activities.

An original design for an electrochemical chamber and the construction of a high-voltage AC generator for electrochemical etching (ECE) of nuclear tracks in CR-39 polycarbonates sheets are presented. The electrochemical chamber was designed and manufactured in an engineering plastic in a vertical machining center. The high-voltage AC generator was built by using different electronic circuits: a signal oscillator, a preamplifier, a power amplifier, two power supplies and a voltage converter transformer. The experimental tests showed that the design of the electrochemical chamber allowed that ECE be developed efficiently, achieving a dielectric breakdown in the polycarbonate, and the generator supplied the electric current in a stable manner and with an excellent performance throughout the ECE. The conditions of chemical etching and electrochemical etching, as well as the electrical treeing generated in the CR-39 are also presented.

A laser beam heats a mixture of ethanol and anthocyanins producing the effect of a reciprocating machine. This behaviour is analyzed in terms of the stable, metastable and unstable states of Landau and Lifschitz. Trying first with the van der Waals equation of state, with negative results because the system state is normally far from the critical state, a modified version, with van der Waals coefficients depending linearly on the temperature is proposed, based in the thermodynamic properties of ethanol at room and critical temperatures. The resulting theory allows us to understand the discontinuous results concerning the absorption of the laser beam in terms of a thermodynamic cycle and its frequency dependence on the laser light focus position. Slight changes in the experimental setup may enable the measurement of thermodynamic properties in metastable states.

A fuzzy logic-based embedded system to characterize materials and metamaterials is presented. Trapezoidal and Gaussian profiles, used as membership functions, allow to classify materials despite variations on light intensity. The results on various materials show the capacity of the system to calculate the refractive index as a complex number, through a fourth order equation. Since all the roots of the equarion, including imaginary ones, the system allow to characterize metamaterials. The embedded character of the systems allows to use it as an external module for most commercial equipments.

Expansive clayey soils produce heaving and cracking of floor slabs and walls. Expansive soils owe their characteristics to the presence of swelling clay minerals. This soil expands and contracts due to changes in the moisture content of the soil. In this study the surcharge required to counteract soil expansion was measured in natural expansive soils (untreated soils) and lime treated soils starting at 19.61 kPa (2 Ton/m2) and continuing with increments of 19.61 kPa. Additionaly in lime treated soils the amount of lime was determined under different surcharges in order to reduce the expansion. The test results indicated that the surcharges applied to untreated soils were not proportional to the decrease of expansion which is probably due to the increase of soil density. In fact, only the initial surcharge of 19.61 kPa significantly decreased the expansion. According to the results, the soil expansion was considerably reduced (1.54%) with the surcharge of 78.45 kPa, therefore this surcharge can be considered as the Swelling pressure. On the other hand the soil tested (high compressibility clay) was stabilized with 6% of lime (without surcharges) which was determined with the lowest value of liquid limit and plastic index as well as expansion test. After the application of surcharges and lime treatment to expansive soil, the surcharges of 39.22 kPa and 58.84 kPa decreased expansion and increased their resistance. This was concluded by similar low values of expansion (without settlements) under both surcharges of each treated soil tested (2, 4 and 6% of lime). It can be concluded that the surcharge contributed to the decrease of soil expansion due to the decrease of the amount of lime required (6%) without surcharge. So, 4% of lime was enough for the surcharge of 19.61 kPa and 2% of lime required the surcharge minimum of 39.22 kPa. This shows that the surcharge of a house on expansive soil reduces soil expansion and therefore reduces costs of any method of soil improvement and special foundation.

Chitosan–starch polymers are reinforced with different keratin materials obtained from chicken feather. Keratin materials are treated with sodium hydroxide; the modified surfaces are rougher in comparison with untreated surfaces, observed by Scanning Electron Microscopy. The results obtained by Differential Scanning Calorimetry show an increase in the endothermic peak related to water evaporation of the films from 92 °C (matrix) up to 102–114 °C (reinforced composites). Glass transition temperature increases from 126 °C in the polymer matrix up to 170–200 °C for the composites. Additionally, the storage modulus in the composites is enhanced up to 1614% for the composites with modified ground quill, 2522% for composites with modified long fiber and 3206% for the composites with modified short fiber. The lysozyme test shows an improved in the degradability rate, the weight loss of the films at 21 days is reduced from 73% for chitosan-starch matrix up to 16% for the composites with 5 wt% of quill; but all films show a biodegradable character depending on keratin type and chemical modification. The outstanding properties related to the addition of treated keratin materials show that these natural composites are a remarkable alternative to potentiating chitosan–starch films with sustainable features.

In several theoretical and experimental studies, the topic of the undesirable generation of photoneutrons in rooms where a linear accelerator (LINAC) operates has been discussed. When energies above 10 MeV are used to produce X-rays and give radiotherapy treatment to patients resulting in additional radiation to patients. Accordingly, an analysis and characterization of the neutron scattering distribution on different zones in a treatment room contributes to evaluate the radiological health risk to patients, technical and other workers involved in treatment. For the evaluation, a device developed at the PAD-IFUNAM formed by a CR-39 detector enclosed by two 3mm thick acrylic plates was employed. To avoid environmental contamination, the CR-39 and the acrylics plates are enclosed in a round plastic box. Sixteen of these devices were settled in different places inside the treatment room, where a linear accelerator is used. The results show a significant concentration of neutron scattering in areas near the head of irradiation. The recommendation will be to evaluate the neutron scattering concentration in all rooms that’s operates a LINAC in order to verify the radiological health risk and to mitigate the neutron scattering when concentration levels are to high like those in our case, in order to avoid unnecessary exposition to patients and personnel in general.

The optical properties of six ionic liquids, modified with 1-buthyl-3-methylimidazolium and 1-ethyl-3-methylimidazolium cations, to form a bi-ionic liquid, was determined by the z-scan technique, revealing a negative nonlinear refractive index, which can be tailored, to some extent, by the composition of the liquid.

Disruption of the continuous cutaneous membrane in the integumentary system is considered a health problem of high cost for any nation. Several attempts have been made for developing skin substitutes in order to restore injured tissue including autologous implants and the use of scaffolds based on synthetic and natural materials. Current biomaterials used for skin tissue repair include several scaffold matrices types, synthetic or natural, absorbable, degradable or non-degradable polymers, porous or dense scaffolds, and cells capsulated in hydrogels or spheroids systems so forth. These materials have advantages and disadvantages and its use will depend on the desired application. Recently, marine organisms such as jellyfish have attracted renewed interest, because both its composition and structure resemble the architecture of human dermic tissue. In this context, the present study aims to generate scaffolds from Cassiopea andromeda (C. andromeda), with application in skin tissue engineering, using a decellularization process. The obtained scaffold was studied by infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential scanning calorimetry analysis (DSC), and scanning electron microscopy (SEM). Crystal violet staining and DNA quantification assessed decellularization effectiveness while the biocompatibility of scaffold was determined with human dermic fibroblasts. Results indicated that the decellularization process reduce native cell population leading to 70% reduction in DNA content. In addition, SEM showed that the macro and microstructure of the collagen I-based scaffold were preserved allowing good adhesion and proliferation of human dermic fibroblasts. The C. andromeda scaffold mimics human skin and therefore represents great potential for skin tissue engineering.

Graphene oxide was synthesized by a one-step environmentally friendly mechanochemistry process directly from graphite and characterized by Raman, FT-IR and UV/vis spectroscopies, Atomic Force Microscopy, X-ray Diffraction, Scanning Electron Microscopy, Energy-Dispersive X-ray Spectroscopy and Thermogravimetric Analysis. Spectroscopic analysis shows that the functional groups and oxygen content of the synthesized material are comparable with those of graphene oxide synthesized by other previously reported methods (Hummers). Thermogravimetric analysis reveals thermal stability up to 400 °C.

Permeability is a key parameter in the analysis of geothermal systems, usually controlled by secondary structures such as fractures, faults or stratigraphic contacts. Contrarily, primary porosity is considered to have a negligible effect on the permeability of those systems, as it is commonly observed that there is low connectivity between macropores (conventionally defined as larger than 1μm). However, we observe that at the micrometric scale this scenario is different, and connectivity is clearly identified. In this study, an updated innovative petrophysical method is developed to calculate microporosity with high precision and simulate permeability on andesite lava flow core-samples from a geothermal production well in Los Humeros Geothermal Field (LHGF), Mexico. The method is based on high-resolution X-ray microCT and numerical post-processing algorithms, producing porosity-permeability estimates, which are in good agreement with other independent petrophysical methods such as Helium porosimetry-permeameter. Our results indicate that macropores account for an average of 3.7 ± 0.9 % of total rock volume fraction, whereas microporosity is generally higher, with a volume fraction in the order of 6.2 ± 0.6 %. Furthermore, when removing microporosity from the pore network, the permeability will account for an average of 3.50 × 10−17 m2, which is only the 17.92 % of the total average permeability for all samples. On the other hand, when microporosity is added, there is an average increment in the permeability of 82.08 %. This means that more than 80 % of the permeability of the samples is due to microporosity, and that microporous space indeed plays a major role in the permeability of these rocks. These results reveal that microporosity plays an important role on the permeability of rocks from volcanic-hosted LHGF. This approach has not been previously fully considered, and in this study, we show that a detailed microporosity analysis is essential for further estimations of permeability of volcanic-hosted geothermal systems.

Summary An innovative dye-sensitized solar cell based on achiote seeds with a new dual electrical generation mechanism is presented. This dye-sensitized solar cell, in addition to the well-known mechanism, where the conduction electrons are released from the dye molecules due to their interaction with photons, shows a distinct chemical mechanism that produces an effective electric current under dark conditions. Both mechanisms operate simultaneously; however, the electrical signal obtained from the photoelectrical mechanism is stronger. Additionally, during a rapid transition from darkness to illuminate conditions, non-linear oscillations in the current signal are produced when the system is shifted rapidly far from equilibrium conditions. Copyright © 2017 John Wiley & Sons, Ltd.

Novel ZnO:Li thermoluminescent phosphors were synthesized by a chemical method. Pellet-shaped samples were exposed to beta radiation to investigate their dosimetric capabilities. Some samples were exposed to beta particle irradiation for doses from 50 up to 1600 Gy, and it was found that the thermoluminescence response is a linear function in all over the dose range studied. The glow curve exhibits two maxima, centered at 385 and 507 K. The maximum located at 507 K shifts to lower temperatures as dose increases, indicating that second order kinetics thermoluminescence processes are involved. The results indicate that these new ZnO:Li phosphors are promising detectors and dosimeters for beta radiation.

A PMMA-SiO 2 –hybrid material was produced through a modified sol–gel route by using as precursors tetraethyl orthosilicate (TEOS), Methyl methacrylate (MMA) and 3-(Trimethoxysilyl)propyl methacrylate (TMSPM) as the coupling agent. The hybrid films were deposited by dip coating onto 316 L stainless steel plates and then these substrates were immersed in a Simulated Body Fluid (SBF) at 5, 10, 15, 20 y 25 days at a constant temperature of 37 °C and pH=7.4. The resulting hydroxylapatite (HAp) overgrown coatings were characterized by X-ray diffraction, scanning electron microscopy and infrared spectroscopy. After 5 days of immersion in SBF the substrate is partially covered with HAp spherulites and after 15 days the surface is entirely and uniformly coated.

A green facile method has been successfully used for the synthesis of graphene oxide sheets decorated with silver nanoparticles (rGO/AgNPs), employing graphite oxide as a precursor of graphene oxide (GO), AgNO(3) as a precursor of Ag nanoparticles (AgNPs), and geranium (Pelargonium graveolens) extract as reducing agent. Synthesis was accomplished using the weight ratios 1:1 and 1:3 GO/Ag, respectively. The synthesised nanocomposites were characterised by scanning electron microscopy, transmission electron microscopy, atomic force microscopy, X‐ray diffraction, UV‐visible spectroscopy, Raman spectroscopy, energy dispersive X‐ray spectroscopy and thermogravimetric analysis. The results show a more uniform and homogeneous distribution of AgNPs on the surface of the GO sheets with the weight ratio 1:1 in comparison with the ratio 1:3. This eco‐friendly method provides a rGO/AgNPs nanocomposite with promising applications, such as surface enhanced Raman scattering, catalysis, biomedical material and antibacterial agent.

Global organizations, including the World Health Organization (WHO), the Environmental Protection Agency of the United States (US-EPA) and the European Atomic Energy Community (EURATOM) recognize that radon gas as one of the main contributors to environmental radiation exposure for humans. Accordingly, a study and analysis of the indoors radon concentrate in the Cholula Pyramid contributes to understand the Radon dynamic inside of the Pyramid tunnels and to evaluate the radiological health risk to visitors, archaeologists, anthropologists and persons who spend extended periods inside the Pyramid. In this paper, the radon measurements along the Pyramid tunnels are presented. The Nuclear Track Methodology (NTM) was chosen for the measurements, using a close end-cup device developed at the Dosimetry Application Project (DAP) of the Physics Institute UNAM, following very well established protocols for the chemical etching and reading with the Counting Analysis Digital Imaging System (CADIS). The Cholula Pyramid consists of eight stages of constructions, each built in different periods of time. Cholula Pyramid is recognized as the pyramid with the largest base in the World, with 400 meters per side and 65 meters high. The tunnels of the pyramid were built in 1931 by architect Ignacio Marquina, with the aim of exploring and studying the structure. The results show an important indoor radon concentration in the measured tunnels, several times higher than levels recommended by United States Environmental Protection Agency (US-EPA). The recommendation will be to mitigate the radon concentration levels, in order to avoid unnecessary exposition to the people.

In this paper, our goal is to improve the understanding of structural control of hybrid materials synthesized by using acid-catalyzed sol–gel reactions of bis-[trimethoxysilylpropyl]amine (BisSi) and 2-hydroxyethyl methacrylate (HEMA) via free radical in a common solvent. Polymer networks compositions were determined by FTIR and 1H-NMR spectroscopy. The thermal properties of the P(HEMA-BisSi) hybrids with different silica content (e.g. 10, 15 and 25 wt%) were determined by thermogravimetric analysis and differential scanning calorimetry. Glass transition temperatures (Tg´s) of P(HEMA-BisSi) networks were also compared with Tg of PHEMA homopolymer. The Tg´ of PHEMA homopolymer was found as 103.74 °C. The thermal stability of these networks was increased with the BisSi content. Scanning electron microscopy images showed that an increase in acid content caused a decrease in the pore size and pore volume as well as in the surface area of the xerogel.

Electrical and morphological properties of a novel composite, consisting of polypyrrole (PPy)/carbon black (CB)/carbon nanotubes (CNT), within a polyethylene (PE) matrix, are reported. The electrical properties were studied according to the type of filler (i.e. PPy, CB or CNT). The resistivity, analyzed by the Van der Pauw method, shows values in the range of (1E+15 for PE to 1.07E−01 for M15) Ω cm. The filler is distributed as one phase within the blended matrix and/or at the interface between the polymers, thus producing a highly homogeneous material. The morphology and degree of dispersion of the PPy/CB/CNTs in the PE matrix at different concentrations were investigated by scanning electron microscopy.

Different carbon allotropes, including vulcan carbon, multiwall carbon nanotubes, graphene, and nanodiamonds, were processed by chemical purification and treated in a mixture of H2SO4–HNO3. The materials were characterized by infrared and Raman spectroscopy as well as by scanning and transmission electron microscopy. Oxidative differences are indicated by Raman through the G band (∼1570 cm−1), D band (∼1340 cm−1), and G’ band (∼2684 cm−1). The crystal size (La) and purity, relative to the amorphous carbonaceous material, were studied as well, along with the morphological changes induced by the treatments.

An extra-cavity pulse generation by thermocavitation in a Hibiscus sabdariffa L. extract (a natural anthocyanin) is presented. This is, to the best of our knowledge, the first experimental demonstration of thermocavitation in a natural extract. It is also demonstrated that the solution of anthocyanins is acting as an optical shutter triggered by thermocavitation.

A novel Agro-industrial IoT (AIIoT) technology and architecture for intelligent frost forecasting in greenhouses via hybrid Artificial Intelligence (AI), is reported. The Internet of Things (IoT) allows the objects interconnection on the physical world using sensors and actuators via the Internet. The smart system was designed and implemented through a climatological station equipped with Artificial Neural Networks (ANN) and a fuzzy associative memory (FAM) for ecological control of the anti-frost disaster irrigation. The ANN forecasts the inside temperature of the greenhouses and the fuzzy control predicts the cropland temperatures for the activation of five output levels of the water pump. The results were compared to a Fourier-statistical analysis of hourly data, showing that the ANN models provide a temperature prediction with effectiveness higher than 90%, as compared to monthly data model. Moreover, results of this process were validated through the determination of the coefficient of variance analysis method ( R 2 ).

In the color palette of mural paintings in the pre-Hispanic city of Teotihuacan, Mexico, the raw materials used to produce the diverse tonalities of red applied to the decoration of their main buildings has been associated with hematite, iron oxides and, to a lesser extent, with cinnabar. The latter has been described as a mineral related to cult and was reserved exclusively for the upper social hierarchies (ruling, religious and military classes). Previous studies have identified cinnabar in loose fragments of mural paintings dated as belonging to the late stages of the stylistic and technological development of the city (Xolalpan phase, 350–550 CE). Nevertheless, it had never been detected directly on standing mural paintings of earlier periods, until now. This research exposes the detection of these valuable minerals in mural designs of early structures of the architectural complex of Quetzalpapalotl, by means of a non-destructive portable X-ray fluorescence technique. The results were verified through the application of other analytical techniques such as scanning electron microscopy with energy dispersive spectroscopy and Raman spectroscopy. The analyses not only confirmed the existence of cinnabar and hematite minerals in mural paintings, but also identified the presence of gypsum as part of the composition of the stuccos. Although gypsum has been found in grounds of the Mayan area, it has never been reported before for the stucco technology in Teotihuacan. The outcomes state an earlier technological development than formerly proposed for mural painting production in Teotihuacan.

The temperature readings for all the 365 days and the 24 hours may be fitted through a 3 × 3 matrix (the so-called T-matrix). The mean square deviation between this fit and the actual meteorological measurements is smaller than three degrees Celsius. Four entries of this (nonsymmetric) matrix may be fixed by other means, leaving only five independent components. However, the same method applied to the humidity measurements produces a larger mean square deviation. A strong stochastical connection is found between the T-temperature matrix and the U-humidity matrix. The computer program, in C, may be used to adjust a (2M + 1) × (2m + 1) matrix simply by changing the arguments at the command line and has been tested with m and M ranging from zero to 11 (eleven) (more than 24 readings per day are necessary for larger values of m). The physical meaning of these constants is given only in the case m = M = 1. Our results have also been connected to fundamental cosmological properties: Earth’s orbit, the ecliptic angle, and the latitude of Querétaro (or whatever geographical location is chosen). A separate program calculates the angular position of the Sun as measured in the sky of Querétaro, to determine the length of the day or the mean value of the solar cosine. This work introduces several new variables which happen to be stochastically connected.

A functionalized epoxy resin (DGEBA) was synthesized from abietic acid, through the esterification and condensation reactions between the carboxyl groups of abietic acid and the basic functional groups of an epoxy resin. This method of synthesis increases the epoxy resin surface adhesion, as well as the chemical and thermal stability, for being used as a protective coating against corrosion of copper plates. Characterization analyses included FTIR and SEM of both raw and functionalized epoxy resin substrates performed. The corrosion performance of these coatings when applied onto Cu and stainless plates was tested in terms of: (i) immersion in a misty saline chamber, under accelerated corrosive conditions; (ii) Taber abrasion and (iii) hardness, adhesion and potentiodynamic polarization. The obtained results indicate the existence of a chemical bond between the epoxy ring and the carboxyl functional groups of abietic acid. This chemical bonding provided an increased adhesion as well as better chemical and thermal stabilities than those of the original resin. The corrosion resistance lining the functionalized epoxy resin films indicated that their anticorrosive efficiency was up to 30% higher than that of the functionalized resin.

For a pendulum of a given length, installed at any fixed latitude, the motion depends on three variables: the total mechanical energy, connected with the maximum angular distance of the bob from the vertical; the projection of the angular momentum along the vertical, connected with the shape of its orbit along the surface of a sphere, which may be described as a veering ellipse recalling the orbit of Mercury; and the angular velocity, Ω, of the rotating reference system given by that of the Earth. When the value of one of these variables is negligible, the ensuing motion has already been calculated in analytical grounds: a plummet, a Foucault pendulum, or a spherical pendulum including as a special case the so-called plane pendulum. This paper offers a Lagrangian approach in the case when Ω is the sidereal angular velocity of the Earth. To our knowledge, these are the first analytical solutions for any boundary conditions. When the boundary conditions are such that the bob passes through the vertical (i.e., the direction defined by the plummet), the behavior of the pendulum is as expected: the veering velocity of the plane equals the angular velocity of the Earth times the sine of the latitude. This state is reached when the projection of its angular momentum along the vertical vanishes. However, if that projection takes any other value, the motion is produced along a veering ellipse and the time rate of advance of the major axis is the sum of the previous result plus the spherical pendulum contribution. Our solutions include, as special cases, those of the spherical pendulum, or the ideal Foucault pendulum with finite amplitude.

Porous material was processed by the mixing, molding and pressing the ceramic material, afterward burnout and sintering; through the forming porous, using corn flour at different concentration (10, 15 and 20 wt.%) as a pore forming agent; in order to determinate the influence of porous on the mechanical, morphological and structural properties. The effect of the volume fraction of corn flour in the mullite matrix, at various sintering temperature from 1100, 1200, 1300 and 1500?C were tested by Diffraction X ray, showing changes in crystalline phases of mullite (3Al2O3-2SiO2), as result of sintered temperatures. Presence of talcum powder in formula, also cause the formation of the cordierite and cristobalite crystalline phases, giving stability and adhesion to the structure of ceramic material. When sintering at temperatures between 1300 to 1500?C, and it was used the concentration of corn flour 15-20 wt.% as forming agent porous, it was found the better mechanical properties. The scanning electron microscopy analysis shows the presence of open porosity and anisotropy.