Experimental High-Resolution Observation of the Truncated Double-Icosahedron Structure: A Stable Twinned Shell in Alloyed Au-Ag Core@Shell Nanoparticles.

Given the binary nature of nanoalloy systems, their properties are dependent on their size, shape, structure, composition, and chemical ordering. When energy and entropic factors for shapes and structure variations are considered in nanoparticle growth, the spectra of shapes become so vast that even metastable arrangements have been reported under ambient conditions. Experimental and theoretical variations of multiply twinned particles have been observed, from the Ino and Marks decahedra to polyicosahedra and polydecahedra with comparable energetic stability among them. Herein, we report the experimental production of a stable doubly truncated double-icosahedron structure (TdIh) in Au-Ag nanoparticles, in which a twinned Ag-rich alloyed shell is reconstructed on a Au-Ag alloyed Ino-decahedral core. The structure, chemical composition, and growth pathway are proposed on the basis of high-angle annular dark-field scanning transmission electron microscopy analysis and excess energy calculations, while its structural stability is estimated by large-scale atomic molecular dynamics simulations. This novel nanostructure differs from other structures previously reported.

Environmental Fe, Ti, Al, Cu, Hg, Bi, and Si Nanoparticles in the Atrioventricular Conduction Axis and the Associated Ultrastructural Damage in Young Urbanites: Cardiac Arrhythmias Caused by Anthropogenic, Industrial, E-Waste, and Indoor Nanoparticles.

Air pollution exposure is a risk factor for arrhythmia. The atrioventricular (AV) conduction axis is key for the passage of electrical signals to ventricles. We investigated whether environmental nanoparticles (NPs) reach the AV axis and whether they are associated with ultrastructural cell damage. Here, we demonstrate the detection of the shape, size, and composition of NPs by transmission electron microscopy (TEM) and energy-dispersive X-ray spectrometry (EDX) in 10 subjects from Metropolitan Mexico City (MMC) with a mean age of 25.3 ± 5.9 and a 71-year-old subject without cardiac pathology. We found that in every case, Fe, Ti, Al, Hg, Cu, Bi, and/or Si spherical or acicular NPs with a mean size of 36 ± 17 nm were present in the AV axis in situ, freely and as conglomerates, within the mitochondria, sarcomeres, lysosomes, lipofuscin, and/or intercalated disks and gap junctions of Purkinje and transitional cells, telocytes, macrophages, endothelium, and adjacent atrial and ventricular fibers. Erythrocytes were found to transfer NPs to the endothelium. Purkinje fibers with increased lysosomal activity and totally disordered myofilaments and fragmented Z-disks exhibited NP conglomerates in association with gap junctions and intercalated disks. AV conduction axis pathology caused by environmental NPs is a plausible and modifiable risk factor for understanding common arrhythmias and reentrant tachycardia. Anthropogenic, industrial, e-waste, and indoor NPs reach pacemaker regions, thereby increasing potential mechanisms that disrupt the electrical impulse pathways of the heart. The cardiotoxic, oxidative, and abnormal electric performance effects of NPs in pacemaker locations warrant extensive research. Cardiac arrhythmias associated with nanoparticle effects could be preventable.

Effect of Pluronic P103 Concentration on the Simple Synthesis of Ag and Au Nanoparticles and Their Application in Anatase-TiO2 Decoration for Its Use in Photocatalysis.

Silver and gold nanoparticles were synthesized under environmentally-friendly reaction conditions by using a biodegradable copolymer and water as a solvent. The triblock copolymer Pluronic P103 was utilized as a stabilizing agent or soft template to produce Ag and Au nanoparticles (NPs) of different sizes. Moreover, in the synthesis of Au NPs, the polymer acted as a reducing agent, decreasing the number of reagents used and consequently the residues produced, hence, rendering the procedure less complicated. It was observed that as the concentration of the polymer increased, the size of the metallic NPs augmented as well. However, AgNPs and AuNPs prepared with 1 and 10 wt% Pluronic P103, respectively, showed a significant decrease in particle size due to the presence of polymeric soft templates. The hybrid materials (metal/polymer) were characterized by UV-Vis spectroscopy, DLS, and TEM. The pre-synthesized nanoparticles were employed to decorate anatase-TiO2, and the composites were characterized by DRS, XRD, BET surface area measurements, the TEM technique with the EDS spectrum, and XPS spectroscopy to demonstrate NPs superficial incorporation. Finally, methylene blue was used as a probe molecule to evidence the effect of NPs decoration in its photocatalytic degradation. The results showed that the presence of the NPs positively affected methylene blue degradation, achieving 96% and 97% removal by utilizing TAg0.1 and TAu10, respectively, in comparison to bare anatase-TiO2 (77%).

Heterojunction of CuO nanoclusters with TiO2 for photo-oxidation of organic compounds and for hydrogen production.

Heterojunctions of small CuO nanoclusters (synthesized by radiolysis) with TiO2 (commercial P25) induced a photocatalytic activity under visible light irradiation in a wide range of wavelengths due to the narrow bandgap of CuO nanoclusters of around 1.7 eV. The optical, chemical, and electrical properties of these composite nanomaterials were studied. The photocatalytic properties of bare and modified TiO2-P25 were studied for water purification (photooxidation of organic compounds such as phenol and 2-propanol) and for hydrogen generation under visible light irradiation. Time resolved microwave conductivity signals showed activation of TiO2 under visible light, proving the injection of electrons from CuO nanoclusters to the conduction band of TiO2-P25. The modified materials showed high photocatalytic activity under visible light. The important role of charge-carriers was demonstrated for both photoreduction and photooxidation reactions.

Anthropogenic Iron Oxide Nanoparticles Induce Damage to Brain Microvascular Endothelial Cells Forming the Blood-Brain Barrier.

BACKGROUND: Iron nanoparticles, mainly in magnetite phase (Fe3O4 NPs), are released to the environment in areas with high traffic density and braking frequency. Fe3O4 NPs were found in postmortem human brains and are assumed to get directly into the brain through the olfactory nerve. However, these pollution-derived NPs may also translocate from the lungs to the bloodstream and then, through the blood-brain barrier (BBB), into the brain inducing oxidative and inflammatory responses that contribute to neurodegeneration. OBJECTIVE: To describe the interaction and toxicity of pollution-derived Fe3O4 NPs on primary rat brain microvascular endothelial cells (rBMECs), main constituents of in vitro BBB models. METHODS: Synthetic bare Fe3O4 NPs that mimic the environmental ones (miFe3O4) were synthesized by co-precipitation and characterized using complementary techniques. The rBMECs were cultured in Transwell® plates. The NPs-cell interaction was evaluated through transmission electron microscopy and standard colorimetric in vitro assays. RESULTS: The miFe3O4 NPs, with a mean diameter of 8.45±0.14 nm, presented both magnetite and maghemite phases, and showed super-paramagnetic properties. Results suggest that miFe3O4 NPs are internalized by rBMECs through endocytosis and that they are able to cross the cells monolayer. The lowest miFe3O4 NPs concentration tested induced mid cytotoxicity in terms of 1) membrane integrity (LDH release) and 2) metabolic activity (MTS transformation). CONCLUSION: Pollution-derived Fe3O4 NPs may interact and cross the microvascular endothelial cells forming the BBB and cause biological damage.

Reduced graphene oxide decorated with magnetite nanoparticles enhance biomethane enrichment.

The addition of magnetite nanoparticles (MNPs), reduced graphene oxide (rGO), and reduced graphene oxide decorated with magnetite nanoparticles (rGO-MNPs) was evaluated during biomethane enrichment process. rGO-MNPs presented the highest beneficial impact on the hydrogenotrophic assays with an improvement of 47 % in CH4 production. The improvement was linked to the increase of the electron shuttling capacity (ESC) by rGO-MNPs addition, which boosted the hydrogenotrophic activity of microorganisms, to the rGO and rGO-MNPs, which served as reservoirs of hydrogen, improving H⁠2 transport from the gas to the liquid phase, and to the iron ions released, which acted as a dietary supply for microorganisms. Raman and XRD confirmed a greater disorder and lower crystallinity of rGO-MNPs after the hydrogenotrophic assays, with a lower effect at a nanoparticle concentration of 50 mg/L. Moreover, FTIR analysis indicated that rGO-MNPs were oxidized during the hydrogenotrophic tests. This study highlights the advantages of adding rGO-MNPs as a magnetic nanocomposite. Furthermore, rGO-MNPs can be easily recovered, minimizing their release to the environment.

Treatment of tequila vinasse and elimination of phenol by coagulation-flocculation process coupled with heterogeneous photocatalysis using titanium dioxide nanoparticles.

In this research, we are reporting the treatment of tequila vinasse by a coagulation-flocculation process coupled with heterogeneous photocatalysis using two types of titanium dioxide nanoparticles, i.e. (1) commercial nanoparticles, and (2) nanoparticles synthesized by sol-gel. The efficiency in the elimination of phenol, which is one of the most harmful contaminants in tequila vinasse, was also included in the evaluation of the treatment process. The synthesized titanium dioxide nanoparticles were annealed in air at 400°C for 1 h and were characterized by X-ray diffraction, transmission electron microscopy, ultraviolet-visible and Raman spectroscopy. Anatase phase was observed in both samples, with a crystallite size of 22.5 and 9.8 nm for commercial and synthesized nanoparticles respectively. Tequila vinasse was characterized before and after the treatments by measuring physicochemical parameters such as pH, chemical oxygen demand (COD), colour, total suspended solids (TSS), as well as using ultraviolet-visible spectroscopy and Raman spectroscopy to identify the presence of organic compounds, and gas chromatography (GC) for phenol quantification. Raw vinasse was treated initially by coagulation-flocculation producing clarified vinasse, which in turn was treated by photocatalysis for 3 h using hydrogen peroxide as oxidizing agent. The use of synthesized titanium dioxide nanoparticles allowed the highest efficiencies, reaching reductions of 99.4%, 86.0%, and 70.0% for TSS, colour, and COD respectively. GC results showed the reduction of phenol concentrations in 89.7% with our synthesized nanoparticles in contrast to 82.7% reduction, with commercial titanium dioxide nanoparticles.

The Decmon: a new nanoparticle shape along the truncation path from the icosahedron to the decahedron.

The idea that shape and structure determines functionality is one of the leiv-motifs that drives research and applications on fields such as catalysis and plasmonics. The growth and stability of metallic clusters is extensively discussed through faceting and energy minimization mechanisms, respectively. Facet truncations on the regular Mackay-icosahedron (m-Ih) give rise to two sub-families exhibiting five-fold symmetry and external decahedral shape. Such successive truncations made to the regular m-Ih, led to a decahedral motif called 'Decmon' (Montejano's decahedron). This structure expose facets (111) and (100), that after a total energy minimization through molecular dynamics simulations using the embedded atom model, proved to be thermally stable. This result has been confirmed by using nano-thermodynamics. The surface energy competition between the (111) and (100) facets explains its stability at some given cluster sizes, and this truncation path permits to glimpse the potential energy surface in the growth path of nanoparticles from the decahedral (s-Dh) to icosahedral (m-Ih) structures.

Synthesis and thermoluminescent response to γ-rays and neutrons of MgB4O7:Dy and MgB4O7:Dy,Na.

MgB4O7 doped with rare earths and alkaline elements has been reported as a good TLD because of its high sensitivity, effective atomic number close to that of biological tissue and low fading. In this work, thermoluminescent matrices were synthesized of MgB4O7:Dy and MgB4O7:Dy, Na to evaluate their thermoluminescent response (TL) when exposed to γ-rays and neutrons. The amount of Dy was studied in a concentration range of 0.01-1.5 mol% of total doping, while for Na the concentration of 0.5 mol% was established to determine the TL response as a function of doping. The synthesis of the powders was carried out by the method of wet reaction assisted by heat treatment and the samples were characterized by techniques of scanning electron microscopy and X-ray diffraction to determine the size of grain and crystallographic phase. For the dosimetric study, thermoluminescent phosphors were irradiated with a source of 137Cs at an estimated dose 6.8 ±â€¯0.4 mGy to evaluate their response to γ-rays exposure, while for neutrons a source of 241AmBe was used (estimated dose of 3.1 ±â€¯0.1 mGy). The thermoluminescent responses are similar for all materials exposed to γ-rays as for neutrons, the differences are shown to 280 °C, where a peak of high temperature is observed in materials exposed to neutrons.

Inhibition of Fungal Growth Using Modified TiO2 with Core@Shell Structure of Ag@CuO Clusters.

The photocatalytic disinfection (PCD) properties of TiO2 have attracted attention in the research communities because the produced reactive oxygen species (ROS) allow destruction of different types of microbes, such as fungi, bacteria, viruses, algae, unicellular organisms, etc. on surfaces, in water, and in air. However, TiO2 requires UV irradiation to produce the ROS, which limits its photoactivity in indoor environments. Surface-modified TiO2 with small Ag and CuO nanoclusters in a core-shell structure exhibits antifungal properties under dark and visible conditions, possibly because of the interaction between Ag-CuO nanoclusters in the fungi membrane and their penetration, and the co-presence of Cu2+ and Ag+ ions. Therefore, a synergetic effect is obtained with co-modification of TiO2 with silver and copper, and the sample Ag@CuO/TiO2 (core-shell structure of Ag-Cu in a ratio of 1:3) exhibits the highest antifungal activity; that is, fungi growth inhibition is observed for Aspergillus melleus and Penicillium chrysogenum. Moreover, significant inhibitions of the sporulation and generation of droplets, possibly containing mycotoxins and sclerotia under dark and visible exposure, are also obtained.

Electrum, the Gold-Silver Alloy, from the Bulk Scale to the Nanoscale: Synthesis, Properties, and Segregation Rules.

The alloy Au-Ag system is an important noble bimetallic phase, both historically (as "Electrum") and now especially in nanotechnology, as it is applied in catalysis and nanomedicine. To comprehend the structural characteristics and the thermodynamic stability of this alloy, a knowledge of its phase diagram is required that considers explicitly its size and shape (morphology) dependence. However, as the experimental determination remains quite challenging at the nanoscale, theoretical guidance can provide significant advantages. Using a regular solution model within a nanothermodynamic approach to evaluate the size effect on all the parameters (melting temperature, melting enthalpy, and interaction parameters in both phases), the nanophase diagram is predicted. Besides an overall shift downward, there is a "tilting" effect on the solidus-liquidus curves for some particular shapes exposing the (100) and (110) facets (cube, rhombic dodecahedron, and cuboctahedron). The segregation calculation reveals the preferential presence of silver at the surface for all the polyhedral shapes considered, in excellent agreement with the latest transmission electron microscopy observations and energy dispersive spectroscopy analysis. By reviewing the nature of the surface segregated element of different bimetallic nanoalloys, two surface segregation rules, based on the melting temperatures and surface energies, are deduced. Finally, the optical properties of Au-Ag nanoparticles, calculated within the discrete dipole approximation, show the control that can be achieved in the tuning of the local surface plasmon resonance, depending of the alloy content, the chemical ordering, the morphology, the size of the nanoparticle, and the nature of the surrounding environment.

Carcinoma de células escamosas de pene / Penis squamous cell carcinoma

El cáncer se ha convertido en un problema sanitario de primer orden a nivel mundial, a pesar de los grandes programas diagnósticos y terapéuticos alcanzados en los últimos años. Se presenta el caso clínico de un paciente de 81 años de edad, con antecedentes de conducta sexual promiscua y desprotegida a lo largo de la vida, el cual presenta una lesión vegetante en glande y numerosas adenopatías inguinales. La biopsia confirma el diagnóstico de carcinoma escamoso infiltrante del pene. Es una patología relativamente rara, que se diagnostica generalmente de forma tardía. Se valoró amputación parcial del pene, pero la familia no autorizó la intervención quirúrgica. El estado general del paciente fue empeorando hasta que falleció (AU)

Cancer has become a first order health problem worldwide, despite the great diagnostic and therapeutic programs achieved during the last years. This is a clinical case of an 81- year-old patient with personal and social history of promiscuous and unprotected sexual behavior that shows a vegetative lesion in his gland and numerous inguinal adenopathies. Biopsy confirms the diagnosis of squamous cell carcinoma infiltrating the penis, which is a relatively rare pathology which is generally diagnosed belatedly. Partial amputation of the penis was considered to be performed, but there was no consent on behalf of his family. The patients general condition was getting worse until he died (AU)

Algunas consideraciones sobre la enfermedad renal crónica en el anciano desde la atención primaria de salud / Some considerations about the chronic kidney disease in the elderly, from the health primary attention

Se realizó una revisión bibliográfica con el objetivo de exponer la situación actual del diagnóstico y manejo de la enfermedad renal crónica en el anciano, con la aplicación de las guías KDOQI (Guías Clínicas Prácticas), introducidas por la National Kidney Foundation (NKF) y la Kidney Disease Improving Global Outcomes (KDIGO). Partiendo de los cambios producidos por el envejecimiento en el riñón, se valora la viabilidad de la aplicación de las mismas en los ancianos. Se comparan los métodos más utilizados para el cálculo del filtrado glomerular estimado: Cockcroft-Gault y más recientemente el Modification of Diet in Renal Disease (MDRD), resaltando la fiabilidad y rapidez del primero en el contexto cubano. Se describen las particularidades de la enfermedad renal crónica en el adulto mayor y el manejo de la misma con énfasis en la Atención Primaria de Salud. Se concluye que las guías KDOQI son una herramienta excepcional para la prevención, más que como un factor determinante para el diagnóstico de la enfermedad renal en el caso del paciente geriátrico(AU)

A bibliographical revision was carried out with the objective of exposing the current situation of the diagnosis and handling of the chronic kidney disease in the elderly with the application of the KDOQI guides (clinic practical guides) introduced by the National Kidney Foundation (NKF) and the Kidney Disease: Global Improving Outcomes (KDIGO). Taking the changes produced by the aging of the kidney as a starting point, the feasibility of the application of those guides in the elderly is assessed. The methods mostly used are compared for the calculation of the glomerular filtration rate: Cockcroft-Gault, and more recently, the Modification of Diet in Renal Disease (MDRD), standing out the reliability and speed of the first one in the Cuban context. The characteristics of the chronic kidney disease in the elderly are described, as well as its management, placing emphasis on the Health Primary Attention. It concludes that the KDOQI guides are an exceptional tool, better for prevention than as a determining factor for the diagnosis of the kidney disease in the case of the elderly patient(AU)

Coronary lesions quantification with dual-axis rotational coronary angiography.

BACKGROUND: Coronary angiography (CA) has been the gold standard technique for studying coronary artery disease. It is based on the analysis of bidimensional orthogonal projections that may not be optimal to estimate determinate coronary segments. Rotational angiography "Xperswing" (DARCA) is a new technique that allows the visualization of the coronary arteries from multiple views, with a single contrast injection. The aim of this study is to evaluate the coronary lesions quantification with DARCA. METHODS: Quantitative coronary analysis of significant coronary stenosis (>50%) was performed. Every lesion was measured in two different projections: the "optimal projection", obtained by DARCA and defined by the operator as the one with a better lesion qualification, and the "standard projection", corresponding to the usual projection closer to the optimal one in obliquity and angulation. Measures were performed twice and by two independent operators. Intra- and inter-observer correlation was estimated by Kappa index and variables were compared with t Student test (SPSS 14.0). RESULTS: 205 lesions in 147 patients were analyzed. Kappa coefficient intra-observer was 0.80 and 0.86 respectively with an inter-observer correlation index of 0.72. Lesion length and maximal diameter of the vessel were significantly greater in the group of RA. In the segments analysis, calculated length was longer for the first diagonal branch, first marginal obtuse artery, middle circumflex, middle and distal RCA and posterior descending artery, with greater reference diameters for proximal LAD and distal RCA. There were no significant differences for coronary stenosis grade. CONCLUSIONS: RA XperSwing provides a better visualization of coronary arteries improving lesions characterization, with longer measured lesions length and greater vessel diameters, especially in coronary segments with more angulation.

Experimental and DFT studies of gold nanoparticles supported on MgO(111) nano-sheets and their catalytic activity.

A wet chemical preparation of MgO with the (111) facet as the primary surface has recently been reported and with alternating layers of oxygen anions and magnesium cations, this material shows unique chemical and physical properties. The potential to utilize the MgO(111) surface for the immobilization of metal particles is intriguing because the surface itself offers a very different environment for the metal particle with an all oxygen interface, as opposed to the typical (100) facet that possesses alternating oxygen anion and magnesium cation sites on the surface. Gold nanoparticles have demonstrated a broad range of interesting catalytic properties, but are often susceptible to aggregation at high temperatures and are very sensitive to substrate effects. Here, we investigate gold-supported on MgO(111) nanosheets as a catalyst system for the aerobic oxidation of benzyl alcohol. Gold nanoparticles deposited on MgO(111) show an increased level of activity in the solvent-free benzyl alcohol aerobic oxidation as compared to gold nanoparticles deposited on a typical MgO aerogel. TEM studies reveal that the gold nanoparticles have a hemispherical shape while sitting on the main surface of MgO(111) nanosheets, with a large Au-MgO interface. Given that the gold nanoparticles deposited on the two types of MgO have similar size, and that the two types of unmodified MgO show almost the same activities in the blank reaction, we infer that the high activity of Au/MgO(111) is due to the properties of the (111) support and/or those of the gold-support interface. To understand the binding of Au on low-index MgO surfaces and the charge distribution at the surface of the support, we have performed density functional theory (DFT) calculations on all low-index MgO substrates (with and without gold), using a model Au(10) cluster. Due to similar lattice constants of Au(111) and MgO(111) planes, the Au cluster retains its structural integrity and binds strongly on MgO(111) with either oxygen or magnesium termination. Furthermore, we have found that for the (001) and (110) substrates the charges of the ions in the top surface layer have similar values as in bulk MgO, but that on (111) surfaces these charges are significantly different. This difference in surface charge determines the direction of the electronic transfer upon adsorption of gold, such transfer occurring so as to restore the bulk MgO charge values. Using the results from theoretical calculations, we provide an explanation of our observations of increased catalytic activity in the case of the Au/MgO(111) system.