A Simple Way to Produce Gold Nanoshells for Cancer Therapy

Gold nanoshells (GNSs), formed by a silica core surrounded by a gold shell, present a shift on their surface plasmon resonance (SPR) to the near-infrared (NIR) part of the electromagnetic spectrum when synthesized with specific dimensions. This chapter presents a simple method to prepare the nanoshells, a step-by-step characterization, as well as their absorbance spectrum. For the synthesis, silica spheres, with approximately 190 ± 5 nm in diameter, were prepared using the Stöber method and then functionalized with 3-aminopropyltriethoxysilane (APTES). The gold nanoparticles (GNPs), with a diameter of 7 ± 3 nm, were produced by the reduction of chloroauric acid. Then, the silica was seeded with the GNPs to later grow a gold shell with the help of Au(OH)4¯ ions and formaldehyde. UV-Vis spectroscopy results showed an increase of absorbance starting at 520 nm. It reached its maximum around 600 nm and kept absorbing all through 1200 nm. Transmission electron microscope (TEM) and scanning electron microscope (SEM) images suggest that the absorption peak movement coincided with the completion of the shell. Furthermore, when the sample was irradiated with an 820 nm wavelength/3.1 mW laser, its temperatures increased by 6.3°C in 2 min, showing its absorbance in the NIR

Síntesis y caracterización de nano-monocristales de Glicina-Nitrato de Sodio, GSN, con propiedades ópticas no-lineales

Cristales de glicina-nitrato de sodio (GSN) fueron sintetizados a partir de evaporación de soluciones acuosas a temperatura ambiente. Tales cristales fueron caracterizados por espectroscopia infrarroja (IR), espectroscopia ultravioleta-visible (UV-Vis), difracción de rayos-X (DRX), análisis térmico (DTA-TGA) y microscopia electrónica de barrido (MEB). La espectroscopia UV-Vis muestra que los materiales son transparentes en el rango de 500- 1000 nm, indicando que son deseables para la generación de segundo armónico. Los resultados de difracción de rayos-X confirman que se cristalizan en el sistema  monoclínico grupo espacial Cc con parámetros de red a = 14,329 D, b = 5,2662 D, c = 9,1129 D, con ángulo β = 119,10°. El análisis térmico muestra que los cristales son estables por debajo de los 190 °C, lo cual es de suma importancia para aplicaciones tecnológicas futuras

Electrochemical Impedance Spectroscopy Behavior of Nanometric Al-Cr and Cr-Al Coatings by Magnetron Sputtering

Multilayer and bilayers structures have attracted much attention as a way of improving the mechanical and corrosion resistance properties of protective coatings. In this work the application of nanometric Al/Cr and Cr/Al bilayers deposited on AA2024-T3, AA60601-T6 aluminum alloys and AISI 9840 steel by magnetron sputtering and DC sputtering was studied. The materials were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and electrochemical impedance spectroscopy (EIS) in order to consider their application as high corrosion resistance coatings. The corrosion behavior of the films was studied using a NaCl aqueous solution (3.5 wt %

A comparative study of the physical properties of Sb2S3 thin films treated with N2 AC plasma and thermal annealing in N2.

As-deposited antimony sulfide thin films prepared by chemical bath deposition were treated with nitrogen AC plasma and thermal annealing in nitrogen atmosphere. The as-deposited, plasma treated, and thermally annealed antimony sulfide thin films have been characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy, scanning electron microscopy, atomic force microscopy, UV–vis spectroscopy, and electrical measurements. The results have shown that post-deposition treatments modify the crystalline structure, the morphology, and the optoelectronic properties of Sb2S3 thin films. X-ray diffraction studies showed that the crystallinity of the films was improved in both cases. Atomic force microscopy studies showed that the change in the film morphology depends on the postdeposition treatment used. Optical emission spectroscopy (OES) analysis revealed the plasma etching on the surface of the film, this fact was corroborated by the energy dispersive X-ray spectroscopy analysis. The optical band gap of the films (Eg) decreased after post-deposition treatments (from 2.36 to 1.75 eV) due to the improvement in the grain sizes. The electrical resistivity of the Sb2S3 thin films decreased from 108 to 106 V-cm after plasma treatments

Naica's "Cueva de los Cristales": Synchrotron radiation characterization of the wall-crystal interface

Naica's "Cueva de los Cristales" was discovered in 2000. It has been considered particularly interesting for its beauty and the challenges it poses to crystallography. This article focuses on the study of the wall-selenite interface by various techniques, particularly X-ray diffraction (XRD), scanning electron microscopy (SEM), with emphasis on micro-X-ray fluorescence (micro-XRF) and micro-X-ray absorption near edge structure (micro-XANES). The main phases calcite, quartz, goethite and montmorillonite were identified by XRD, as well as the association of crystalline and amorphous minor and trace phases of Zn, Mn, Cu, As and Pb. The latter were identified in micro-XRF maps and micro-XANES spectra. The results for the morphology and the chemical description of the crystal-wall interface may contribute to propose a nucleation and growth mechanism for Naica megacrystals

Síntesis y caracterización de nano-monocristales de Glicina-Nitrato de Sodio, GSN, con propiedades ópticas no-lineales

Cristales de glicina-nitrato de sodio (GSN) fueron sintetizados a partir de evaporación de soluciones acuosas a temperatura ambiente. Tales cristales fueron caracterizados por espectroscopia infrarroja (IR), espectroscopia ultravioleta-visible (UV-Vis), difracción de rayos-X (DRX), análisis térmico (DTA-TGA) y microscopia electrónica de barrido (MEB). La espectroscopia UV-Vis muestra que los materiales son transparentes en el rango de 500- 1000 nm, indicando que son deseables para la generación de segundo armónico. Los resultados de difracción de rayos-X confirman que se cristalizan en el sistema  monoclínico grupo espacial Cc con parámetros de red a = 14,329 D, b = 5,2662 D, c = 9,1129 D, con ángulo β = 119,10°. El análisis térmico muestra que los cristales son estables por debajo de los 190 °C, lo cual es de suma importancia para aplicaciones tecnológicas futuras

Antimicrobial Resistance and Inorganic Nanoparticles

Antibiotics are being less effective, which leads to high mortality in patients with infections and a high cost for the recovery of health, and the projections that are had for the future are not very encouraging which has led to consider antimicrobial resistance as a global health problem and to be the object of study by researchers. Although resistance to antibiotics occurs naturally, its appearance and spread have been increasing rapidly due to the inappropriate use of antibiotics in recent decades. A bacterium becomes resistant due to the transfer of genes encoding antibiotic resistance. Bacteria constantly mutate; therefore, their defense mechanisms mutate, as well. Nanotechnology plays a key role in antimicrobial resistance due to materials modified at the nanometer scale, allowing large numbers of molecules to assemble to have a dynamic interface. These nanomaterials act as carriers, and their design is mainly focused on introducing the temporal and spatial release of the payload of antibiotics. In addition, they generate new antimicrobial modalities for the bacteria, which are not capable of protecting themselves. So, nanoparticles are an adjunct mechanism to improve drug potency by reducing overall antibiotic exposure. These nanostructures can overcome cell barriers and deliver antibiotics to the cytoplasm to inhibit bacteria. This work aims to give a general vision between the antibiotics, the nanoparticles used as carriers, bacteria resistance, and the possible mechanisms that occur between them

Evolution of the Atonishing Naica Giant Crystals in Chihuahua, Mexico

Calcium sulfate (CaSO4) is one of the most common evaporites found in the earth’s crust. It can be found as four main variations: gypsum (CaSO4·2H2O), bassanite (CaSO4 ·0.5H2O), soluble anhydrite, and insoluble anhydrite (CaSO4), being the key difference the hydration state of the sulfate mineral. Naica giant crystals’ growth starts from a supersaturated solution in a delicate thermodynamic balance close to equilibrium, where gypsum can form nanocrystals able to grow up to 11–12 m long. The growth rates are reported to be as slow as (1.4 ± 0.2) × 10−5 nm/s, taking thousands of years to form crystals with a unique smoothness and diaphaneity, which may or may not include solid or liquid inclusions. Conservation efforts can be traced back to other gypsum structures found prior to Naica’s. Furthermore, in the last two decades, several authors have explored the unique requirements in which these crystals grow, the characterization of their environment and microclimatic conditions, and the prediction of deterioration scenarios. We present a state-of-the-art review on the mentioned topics. Beyond the findings on the origin, in this work we present the current state and the foreseeable future of these astounding crystals.The support provided by CONACYT Project No. 183706, the proposals SSRL 3939, the ESRF HG-77, Elettra Sincrotrone-Trieste 20155328, as well as by the International Centre for Theoretical Physics (ICTP) are acknowledged. Special thanks to Manuel Reyes-Cortés, who provided some of the key research samples and supported their selection and analysis. The authors thank the cooperation of the management of the Peñoles company, the Desert Museum of Ciudad Delicias, Chihuahua, the Harvard Museum of Natural History, and the Faculty of Engineering of the Autonomous University of Chihuahua for providing essential specimens for the study. The authors thank the anonymous referees for their helpful suggestions

A Paper-Based Microfluidic Fuel Cell Using Soft Drinks as a Renewable Energy Source

The research aims were to construct an air-breathing paper-based microfluidic fuel cell (paper-based μ FC) and to evaluated it with different soft drinks to provide energy for their prospective use in portable devices as an emergency power source. First, in a half-cell configuration, cyclic voltammetry showed that glucose, maltose, and fructose had specific oxidation zones in the presence of platinum-ruthenium on carbon (PtRu/C) when they were individual. Still, when they were mixed, glucose was observed to be oxidized to a greater extent than fructose and maltose. After, when a paper-based μ FC was constructed, PtRu/C and platinum on carbon (Pt/C) were used as anode and cathode, the performance of this μ FC was mostly influenced by the concentration of glucose present in each soft drink, obtaining maximum power densities at room temperature of 0.061, 0.063, 0.060, and 0.073 mW cm − 2 for Coca Cola ® , Pepsi ® , Dr. Pepper ® , and 7up ® , respectively. Interestingly, when the soft drinks were cooled, the performance was increased up to 85%. Furthermore, a four-cell stack μ FC was constructed to demonstrate its usefulness as a possible power supply, obtaining a power density of 0.4 mW cm − 2 , using Coca Cola ® as fuel and air as oxidant. Together, the results of the present study indicate an alternative application of an μ FC using soft drinks as a backup source of energy in emergencies

Naica’s giant crystals: Deterioration scenarios

The Cave of Giant Crystals of Naica (Chihuahua, Mexico) is a world geological treasure worth to be preserved. These crystals of up to 12 m in length are made of selenite, the macrocrystalline variety of gypsum (CaSO4·2H2O). They have grown for thousands of years until the cave was dried, which allowed the cave and the crystals to be accessible, but exposed their surfaces in contact with air. Gypsum crystals are fragile because of their trend to dehydrate, the possible replacement to CaCO3 upon reactions with atmospheric CO2 as well as their intrinsic mechanical properties. Several laboratory experiments, designed to study the deterioration of selenite crystals under different artificial atmospheric conditions, are presented. Four atmospheric compositions rich in CO2, CH4, NOx, and air were tested for 1 year at temperatures of 25 and 60 °C and in either liquid or gaseous environments. The surface evolution was monitored by optical microscopy, infrared spectrometry, and grazing incidence X-ray diffraction with two-dimensional detectors. Surface alteration and dissolution in a water environment were observed in short exposition times, as well as the formation of bassanite (CaSO4·1/2H2O). Neither anhydrite nor calcite was detected. The gaseous environment constituted the most detrimental conditions to the gypsum crystals integrity.The authors would like to acknowledge Consejo Nacional de Ciencia y Tecnologia (grant number 183706); Industrias Peñoles for the support given to the experiments; A. Reyes-Rojas, D. Burciaga-Valencia, and E. Guerrero-Lastarjette for their continuous support in the realization of this project; and B. Aldea-Ballano and the team of the Chemical and Physicochemical Testing Unit in Instituto Eduardo Torroja de Ciencias de la Construcción in Madrid. The authors especially thank J. M. García-Ruiz for the suggestions of some experiments. Part of the experiments was performed (as part of Proposal No. 3939) at the Stanford Synchrotron Radiation Lightsource (SSRL), a Directorate of SLAC National Accelerator Laboratory and an Office of Science User Facility operated for the U.S. Department of Energy, Office of Science, by Stanford University.Peer reviewe