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The search for new materials that could improve the energy density of Li-ion batteries is one of today's most challenging issues. Many families of transition metal oxides as well as transition metal polyanionic frameworks have been proposed during the past twenty years. Among them, manganese oxides, such as the LiMn2O4 spinel or the overlithiated oxide Li[Li1/3Mn2/3]O2, have been intensively studied owing to the low toxicity of manganese-based materials and the high redox potential of the Mn(3+)/Mn(4+) couple. In this work, we report on a new electrochemically active compound with the 'Li4Mn2O5' composition, prepared by direct mechanochemical synthesis at room temperature. This rock-salt-type nanostructured material shows a discharge capacity of 355 mAh g(-1), which is the highest yet reported among the known lithium manganese oxide electrode materials. According to the magnetic measurements, this exceptional capacity results from the electrochemical activity of the Mn(3+)/Mn(4+) and O(2-)/O(-) redox couples, and, importantly, of the Mn(4+)/Mn(5+) couple also.
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A large class of colloidal multi-micron mesoporous silica particles have well-defined cylindrical nanopores, nanochannels which self-assembled in the templated sol-gel process. These particles are of broad interest in photonics, for timed drug release, enzyme stabilization, separation and filtration technologies, catalysis, etc. Although the pore geometry and mechanism of pore formation of such particles has been widely investigated at the nanoscale, their pore geometry and its formation mechanism at a larger (extended) scale is still under debate. The extended geometry of nanochannels is paramount for all aforementioned applications because it defines accessibility of nanochannels, and subsequently, kinetics of interaction of the nanochannel content with the particle surrounding. Here we present both experimental and theoretical investigation of the extended geometry and its formation mechanism in colloidal multi-micron mesoporous silica particles. We demonstrate that disordered (and consequently, well accessible) nanochannels in the initially formed colloidal particles gradually align and form extended self-sealed channels. This knowledge allows to control the percentage of disordered versus self-sealed nanochannels, which defines accessibility of nanochannels in such particles. We further show that the observed aligning the channels is in agreement with theory; it is thermodynamically favored as it decreases the Gibbs free energy of the particles. Besides the practical use of the obtained results, developing a fundamental understanding of the mechanisms of morphogenesis of complex geometry of nanopores will open doors to efficient and controllable synthesis that will, in turn, further fuel the practical utilization of these particles.
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Ocular tuberculosis (OTB) is a specific infectious (bacterial) disease dealt with by ophthalmologists and phthisiatricians. This is a serious illness with chronic, persistent course and extremely doubtful prognosis. Chemotherapy, even if effective, can still be followed by a decrease in visual acuity. Clinical recovery is often unstable. Ocular tuberculosis is largely associated with permanent disability and, as a result, a decline in quality of life of these patients. Statistical reporting does not always reflect the true prevalence of the disease as it sometimes develops in patients with pre-existing specific pulmonary involvement. This article discusses all pathogenetic mechanisms of OTB that have been described so far. Attention is paid to modern diagnostic methods, including spectral optical coherence tomography. Positive results of endonasal electrophoresis for the treatment of OTB are described.
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Antituberculosos/uso terapéutico , Calidad de Vida , Tuberculosis Ocular , Humanos , Pronóstico , Resultado del Tratamiento , Tuberculosis Ocular/diagnóstico , Tuberculosis Ocular/tratamiento farmacológico , Tuberculosis Ocular/fisiopatología , Tuberculosis Ocular/psicología , Agudeza VisualRESUMEN
AIM: To investigate parameters of intraocular fluid outflow after phacoemulsification of cataract in patients with primary open-angle glaucoma (POAG). MATERIAL AND METHODS: The study involved 153 cataract patients (153 eyes), most of whom also had POAG. The patients were divided into three groups: group 1 - 51 patients (51 eyes) with cataract but no glaucoma, group 2 - 51 patients (51 eyes) with cataract and early POAG, and group 3 - 51 patients (51 eyes) with cataract and advanced POAG. All of them underwent non-contact pneumatic tonometry, tonography, and tonography with vacuum compression (Glau-Test60) before and after surgery (phacoemulsification of cataract with implantation of a posterior chamber intraocular lens (IOL)). The follow-up period was 6 months. RESULTS AND DISCUSSION: Phacoemulsification surgery with IOL implantation was able to reduce intraocular pressure in non-glaucoma cataract patients by 3 to 5 mmHg in 21.57% of cases and by more than 5 mmHg in 58.8% of cases. In patients with early and advanced glaucoma, a 3 to 5 mmHg decrease occurred in 33.3% and 13.7% of cases, respectively, and a more than 5 mmHg decrease - in 49.02% and 56.9%, respectively. This reduction is due to activation of intraocular fluid outflow. CONCLUSION: A postoperative increase in trabecular and uveoscleral outflow has been detected in all groups. The change was more significant in non-glaucoma patients and those with early disease.
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Catarata , Glaucoma de Ángulo Abierto , Presión Intraocular , Facoemulsificación , Anciano , Catarata/complicaciones , Catarata/fisiopatología , Femenino , Glaucoma de Ángulo Abierto/complicaciones , Glaucoma de Ángulo Abierto/diagnóstico , Glaucoma de Ángulo Abierto/fisiopatología , Glaucoma de Ángulo Abierto/cirugía , Humanos , Hidrodinámica , Masculino , Persona de Mediana Edad , Facoemulsificación/efectos adversos , Facoemulsificación/métodos , Tonometría Ocular/métodos , Resultado del TratamientoRESUMEN
The functional or morphological changes associated with systemic diseases make up the bulk of eye pathology. Accordingly, systemic drug therapy for these diseases can affect the eye. Changes of the organ of vision and appropriate ophthalmological advice can assist an internist to diagnose and adequately treat the patient. The article considers possible changes in the organ of vision in the presence of somatic diseases, as well as alterations resulting from drug therapy for these diseases.
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Substantial part of the eye disease manifestations constitute general or systemic diseases. Accordingly, the dosage systemic therapy of these diseases can affect the condition of the eye. Changes of the vision and the appropriate advice ophthalmologist can help the gastroenterologist in the diagnosis and adequate treatment of the patient. The article discusses the possible changes in the organ of vision in diseases of the digestive system and a number of infectious diseases, as well as changes occurring under the influence of drug therapy of these diseases.
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Enfermedades del Sistema Digestivo/complicaciones , Oftalmopatías/etiología , Enfermedades del Sistema Digestivo/diagnóstico , Enfermedades del Sistema Digestivo/tratamiento farmacológico , Enfermedades del Sistema Digestivo/fisiopatología , Oftalmopatías/diagnóstico , Oftalmopatías/fisiopatología , Humanos , Visión Ocular/fisiologíaRESUMEN
On the basis of the Mn(3+) for Fe(3+) substitution in Pb(2-x)Ba(x)Fe2O5, a novel oxide Pb1.3Ba0.7MnFeO5 has been synthesized at normal pressure. Though it belongs to the same structural family, the mixed "MnFe" oxide exhibits a very different structural distortion of its framework compared to the pure "Fe2" oxide, due to the Jahn-Teller effect of Mn(3+). Combined neutron diffraction, high resolution electron microscopy/high angle annular dark field-scanning transmission electron microscopy (HAADF-STEM) investigations allow the origin of this difference to be determined. Here we show that the MO6 octahedra of the double perovskite layers in the "MnFe" structure exhibit a strong tetragonal pyramidal distortion "5 + 1", whereas the "Fe2" structure shows a tetrahedral distortion "4 + 2" of the FeO6 octahedra. Similarly, the MO5 polyhedra of the "MnFe" structure tend toward a tetragonal pyramid, whereas the FeO5 polyhedra of the "Fe2" structure are closer to a trigonal bipyramid. Differently from the oxide Pb(2-x)Ba(x)Fe2O5, which is antiferromagnetic, the oxide Pb1.3Ba0.7MnFeO5 exhibits a spin glass behavior with Tg â¼ 50 K in agreement with the disordered distribution of the Mn(3+) and Fe(3+) species.
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The article provides an overview of the main groups of IOP-lowering drugs which activate uveoscleral outflow in glaucoma and this activation is a key component of mechanism of action of these drugs. The issues related to the change of tone of ciliary muscle and its participation in uveoscleral outflow, and also relationship of accommodation and aqueous flow in glaucoma pathogenesis and possible pharmacological effects of these processes are being discussed.
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Antihipertensivos/uso terapéutico , Humor Acuoso/fisiología , Glaucoma/tratamiento farmacológico , Esclerótica/fisiopatología , Úvea/fisiopatología , Humor Acuoso/efectos de los fármacos , Glaucoma/fisiopatología , Humanos , Presión IntraocularRESUMEN
by performing electrodeless time-resolved microwave conductivity measurements, the efficiency of charge carrier generation, their mobility, and the decay kinetics on photoexcitation were studied in arrays of Si nanowires grown by the vapor-liquid-solid mechanism. Large enhancements in the magnitude of the photoconductance and charge carrier lifetime are found depending on the incorporation of impurities during the growth. They are explained by the internal electric field that builds up, due to higher doped sidewalls, as revealed by detailed analysis of the nanowire morphology and chemical composition.
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This review deals with the influence of secondary pathogenic factors that include impaired circulatory autoregulation, altered axonal transport, a glutamate calcium cascade of reactions, reduced natural antioxidant system, and accumulated lipid peroxidation products in the eye tissues, pseudoexfoliation syndrome, diminished ciliary muscle function on the pathogenesis of primary open-angle glaucoma. The above factors serve as an element of the major pathogenic factors (elevated intraocular pressure, hemodynamic disorders), aggravate the course of a glaucomatous process and should be kept in mind when complex treatment for the disease is used.
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Glaucoma de Ángulo Abierto/metabolismo , Glaucoma de Ángulo Abierto/fisiopatología , Glaucoma de Ángulo Abierto/tratamiento farmacológico , HumanosRESUMEN
Using the Combinatorial Substrate Epitaxy (CSE) approach, we report the stabilization of Dy2Ti2O7 epitaxial monoclinic, layered-perovskite phase Dy2Ti2O7 thin films. To achieve this, the films are deposited on high density, polished La2Ti2O7 polycrystalline ceramic substrates, which are stable as monoclinic layered-perovskites, and were prepared by conventional sintering. Microstructural analysis using electron backscatter diffraction (EBSD), electron diffraction (ED), and high-resolution transmission electron microscopy (HRTEM) support this observation. Further, they reveal that the cubic pyrochlore phase is observed far from the interface as films are grown thicker (100 nm), confirming the importance of substrate-induced phase and space group selection. This works reinforces the vast potential of CSE to promote the stabilization of metastable phases, thus giving access to new functional oxide materials, across a range of novel material systems including ferroelectrics.
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We report on experimental synthesis and theoretical studies of ultrasharp BN-nanocones. Using scanning and transmission electron microscopy, the cone-like morphology of synthesized products was confirmed. Theoretical analysis of the dipole moment nature in h-BN nanocones reveals that the moment has contributions from the polarity of B-N bonds and electronic flexoelectric effect associated with a curved h-BN lattice. The latter phenomenon is predicted on the basis of the extension of the theory of flexoelectric effects in the h-BN lattice through establishing universality of the linear dependence of flexoelectric dipole moments on local curvature in various nano- h-BN networks (nanotubes and fullerenes). Our study of the atomic structure response and its polarization under deformation of nanocones with different apex angles shows the advantageous properties of cones with the smallest angles.
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It is very important to prevent bacterial colonization at the early postoperative stages. There are four major strategies and their corresponding types of antibacterial surfaces specifically designed to fight infection: bactericide release, anti-adhesion, pH-sensitive, and contact-killing. Herein, we aimed at determining the antibacterial efficiency of different types of bactericidal ions and revealing the possible contribution of surface microgalvanic effects arising from a potential difference on heterogeneous surfaces. We considered five types of TiCaPCON films, with Ag, Zn, Pt, Ag + Zn, and Pt + Zn nanoparticles (NPs) on their surface. The Ag-modified film demonstrated a pronounced antibacterial effect at a very low Ag ion concentration of 0.11 ppb in physiological solution that was achieved already after 3 h of immersion in Escherichia coli ( E. coli) bacterial culture. The Zn-containing sample also showed a noticeable antibacterial effect against E. coli and Staphylococcus aureus ( S. aureus) strains, wherein the concentration of Zn ions was 2 orders of magnitude higher (15 ppb) compared with the Ag ions. The presence of Ag NPs accelerated the leaching of Zn ion out of the TiCaPCON-Ag-Zn film, but no synergistic effect of the simultaneous presence of the two bactericidal components was observed. After the incubation of the samples with Ag, Zn, and Ag + Zn NPs in E. coli and S. aureus suspensions for 24 and 8 h, respectively, all bacterial cells were completely inactivated. The Pt-containing film showed a very low Pt ion release, and therefore the contribution of this type of ions to the total bactericidal effect could be neglected. The results of the electrochemical studies and Kelvin probe force microscopy indicated that microgalvanic couples were formed between the Pt NPs and the TiCaPCON film, but no noticeable antibacterial effect against either E. coli or S. aureus strains was observed. All ion-modified samples provided good osteoblastic cell attachment, spreading, and proliferation and therefore were concluded to be nontoxic for cells. In addition, the TiCaPCON films with Ag, Pt, and Zn NPs on their surface demonstrated good osteoconductive characteristics.
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Antibacterianos/química , Escherichia coli , Iones , Plata , Staphylococcus aureus , Titanio , ZincRESUMEN
Order-disorder-order phase transitions in the clathrate-I Ba8Cu16P30 were induced and controlled by aliovalent substitutions of Zn into the framework. Unaltered Ba8Cu16P30 crystallizes in an ordered orthorhombic (Pbcn) clathrate-I superstructure that maintains complete segregation of metal and phosphorus atoms over 23 different crystallographic positions in the clathrate framework. The driving force for the formation of this Pbcn superstructure is the avoidance of Cu-Cu bonds. This superstructure is preserved upon aliovalent substitution of Zn for Cu in Ba8Cu16-x Zn x P30 with 0 < x < 1.6 (10% Zn/Mtotal), but vanishes at greater substitution concentrations. Higher Zn concentrations (up to 35% Zn/Mtotal) resulted in the additional substitution of Zn for P in Ba8M16+y P30-y (M = Cu, Zn) with 0 ≤ y ≤ 1. This causes the formation of Cu-Zn bonds in the framework, leading to a collapse of the orthorhombic superstructure into the more common cubic subcell of clathrate-I (Pm3n). In the resulting cubic phases, each clathrate framework position is jointly occupied by three different elements: Cu, Zn, and P. Detailed structural characterization of the Ba-Cu-Zn-P clathrates-I via single crystal X-ray diffraction, joint synchrotron X-ray and neutron powder diffractions, pair distribution function analysis, electron diffraction and high-resolution electron microscopy, along with elemental analysis, indicates that local ordering is present in the cubic clathrate framework, suggesting the evolution of Cu-Zn bonds. For the compounds with the highest Zn content, a disorder-order transformation is detected due to the formation of another superstructure with trigonal symmetry and Cu-Zn bonds in the clathrate-I framework. It is shown that small changes in the composition, synthesis, and crystal structure have significant impacts on the structural and transport properties of Zn-substituted Ba8Cu16P30.
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Here we report on self-assembly of novel multi-hierarchically structured meso(nano)porous colloidal silica particles which have cylindrical pores of 4-6nm, overall size of â¼10µm and "cracks" of 50-200nm. These cracks make particles look like micro-sponges. The particles were prepared through a modified templated sol-gel self-assembly process. The mechanism of assembly of these particles is investigated. Using encapsulated fluorescent dye, we demonstrate that the spongy particles are advantageous to facilitate dye diffusion out of particles. This multi-hierarchically geometry of particles can be used to improve the particle design for multiple applications to control drug release, rate of catalysis, filtration, utilization of particles as hosts for functional molecules (e.g., enzymes), etc.
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Dióxido de Silicio/síntesis química , Coloides/síntesis química , Coloides/química , Tamaño de la Partícula , Porosidad , Dióxido de Silicio/química , Propiedades de SuperficieRESUMEN
Riboflavin (Rf) is a vitamin and endogenous photosensitizer capable to generate reactive oxygen species (ROS) under UV-blue irradiation and kill cancer cells, which are characterized by the enhanced uptake of Rf. We confirmed its phototoxicity on human breast adenocarcinoma cells SK-BR-3 preincubated with 30-µM Rf and irradiated with ultraviolet light, and proved that such Rf concentrations (60 µM) are attainable in vivo in tumour site by systemic intravascular injection. In order to extend the Rf photosensitization depth in cancer tissue to 6 mm in depth, we purpose-designed core/shell upconversion nanoparticles (UCNPs, NaYF4:Yb3+:Tm3+/NaYF4) capable to convert 2% of the deeply-penetrating excitation at 975 nm to ultraviolet-blue power. This power was expended to photosensitise Rf and kill SK-BR-3 cells preincubated with UCNPs and Rf, where the UCNP-Rf energy transfer was photon-mediated with ~14% Förster process contribution. SK-BR-3 xenograft regression in mice was observed for 50 days, following the Rf-UCNPs peritumoural injection and near-infrared light photodynamic treatment of the lesions.
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Neoplasias Experimentales/tratamiento farmacológico , Fotoquimioterapia/métodos , Fármacos Fotosensibilizantes/uso terapéutico , Riboflavina/uso terapéutico , Animales , Neoplasias de la Mama/tratamiento farmacológico , Células CHO , Carcinoma Pulmonar de Lewis/tratamiento farmacológico , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Cricetulus , Femenino , Fluoruros/química , Humanos , Nanopartículas del Metal/química , Nanopartículas del Metal/uso terapéutico , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos DBA , Neoplasias Experimentales/metabolismo , Neoplasias Experimentales/patología , Especies Reactivas de Oxígeno/metabolismo , Tulio/química , Ensayos Antitumor por Modelo de Xenoinjerto , Iterbio/química , Itrio/químicaRESUMEN
A post-synthesis deposition of vanadium silicalite-1 zeolite nanoparticles in the pores of SBA-15 results in a highly ordered hexagonal templated silica material with V-silicalite zeolitic plugs, giving rise to an increased crystallinity of the amorphous mesoporous walls.
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To study clinical and pathogenetic correlations between different stages of arterial deficiency in obliterating atherosclerosis of lower limbs arteries (OALLA) and various clinical forms of ischemic heart disease (IHD) as well as the influence of different risk factors on OALLA clinical course in different arterial territories. The study included 76 OALLA patients (73 men and 3 women, mean age 56 years). The diagnosis was made on the basis of typical complaints, physical and device examinations. IHD was diagnosed on the basis of typical clinical symptoms and/or findings of the device examinations. OALLA and IHD differ by some risk factors. One of them--chronic alcoholism--is responsible for OALLA progression. This was shown by the analysis of chronic alcoholism prevalence in two groups of patients: with OALLA alone and OALLA in combination with IHD. In the former group alcoholics prevailed (61 vs 24.1%). Chronic alcoholism may be considered as an independent risk factor of OALLA development.
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Arteriosclerosis Obliterante/fisiopatología , Pierna/irrigación sanguínea , Pierna/fisiopatología , Isquemia Miocárdica/fisiopatología , Alcoholismo/complicaciones , Arteriosclerosis Obliterante/complicaciones , Arteriosclerosis Obliterante/etiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Isquemia Miocárdica/complicaciones , Enfermedades Vasculares Periféricas/fisiopatología , Factores de Riesgo , Índice de Severidad de la EnfermedadRESUMEN
Based on the results of examinations of 300 patients with primary glaucoma after trabeculectomy, the author has developed clinical criteria for the evaluation of the intensity of the reparative processes at the site of intervention. Plasma fibronectin levels were found to grow with the progress of glaucoma (from Stage I to Stage II almost twofold). Analysis of correlations and regressions has revealed reliable relationships between plasma fibronectin levels and clinical values of the intensity of reparative processes at the site of surgery. Preoperative measurements of plasma fibronectin help predict with a high degree of probability the hypotensive effect of surgery.
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Cicatriz/sangre , Fibronectinas/sangre , Glaucoma de Ángulo Abierto/sangre , Complicaciones Posoperatorias/sangre , Anciano , Cicatriz/epidemiología , Estudios de Seguimiento , Glaucoma de Ángulo Abierto/complicaciones , Glaucoma de Ángulo Abierto/cirugía , Humanos , Persona de Mediana Edad , Complicaciones Posoperatorias/epidemiología , Trabeculectomía , Cicatrización de HeridasRESUMEN
Collalysin, a proteolytic enzyme, selectively acting on the young connective tissue, is suggested to be used as part of the complex of measures to prevent excessive cicatrization after antiglaucoma surgery. Rabbit experiments with 3H proline confirm the efficacy of the new drug; a more manifest stable hypotensive effect of antiglaucoma surgery in patients with open-angle glaucoma recommend collalysin for clinical application.