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Patients with monoclonal gammopathy can show paraproteinemic keratopathy (PPK) with an indication to treatment. PPK has to be differentiated from corneal dystrophies, systemic metabolic disorders with corneal involvement, as well as from immunologic and inflammatory corneal diseases.
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Enfermedades de la Córnea , Distrofias Hereditarias de la Córnea , Gammopatía Monoclonal de Relevancia Indeterminada , Paraproteinemias , Córnea , Enfermedades de la Córnea/diagnóstico , Enfermedades de la Córnea/etiología , Distrofias Hereditarias de la Córnea/diagnóstico , Distrofias Hereditarias de la Córnea/etiología , Humanos , Gammopatía Monoclonal de Relevancia Indeterminada/diagnóstico , Trastornos de la VisiónRESUMEN
Model bimetallic Pd-Au/HOPG catalysts have been investigated in the CO oxidation reaction using a combination of NAP XPS and MS techniques. The samples have shown catalytic activity at temperatures above 150 °C. The redistribution of Au and Pd on the surface depending on the reaction conditions has been demonstrated using NAP XPS. The Pd enrichment of the bimetallic particles' surface under reaction gas mixture has been shown. Apparently, CO adsorption induces Pd segregation on the surface. Heating the sample under reaction conditions above 150 °C decomposes the Pd-CO state due to CO desorption and reaction and simultaneous Pd-Au alloy formation on the surface takes place. Cooling back down to RT results in reversible Pd segregation due to Pd-CO formation and the sample becomes inactive. It has been shown that in situ studies are necessary for investigation of the active sites in Pd-Au bimetallic systems.
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A novel type of temporal and spatial self-organization in a heterogeneous catalytic reaction is described for the first time. Using in situ x-ray photoelectron spectroscopy, gas chromatography, and mass spectrometry, we show that, under certain conditions, self-sustained reaction-rate oscillations arise in the oxidation of propane over Ni foil because of reversible bulk oxidation of Ni to NiO, which can be observed even with the naked eye as chemical waves propagating over the catalyst surface.
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Iridium oxide based electrodes are among the most promising candidates for electrocatalyzing the oxygen evolution reaction, making it imperative to understand their chemical/electronic structure. However, the complexity of iridium oxide's electronic structure makes it particularly difficult to experimentally determine the chemical state of the active surface species. To achieve an accurate understanding of the electronic structure of iridium oxide surfaces, we have combined synchrotron-based X-ray photoemission and absorption spectroscopies with ab initio calculations. Our investigation reveals a pre-edge feature in the O K-edge of highly catalytically active X-ray amorphous iridium oxides that we have identified as O 2p hole states forming in conjunction with Ir(III). These electronic defects in the near-surface region of the anionic and cationic framework are likely critical for the enhanced activity of amorphous iridium oxides relative to their crystalline counterparts.
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The oxidation of copper catalysts during ethylene epoxidation was characterized using in situ photoemission spectroscopy and electron microscopy. Gas chromatography, proton-transfer reaction mass spectrometry and electron-ionization mass spectrometry were used to characterize the catalytic properties of the oxidized copper. We find that copper corrodes during epoxidation in a 1 : 1 mixture of oxygen and ethylene. The catalyst corrosion passes through several stages, beginning with the formation of an O-terminated surface, followed by the formation of Cu2O scale and eventually a CuO scale. The oxidized catalyst exhibits measurable activity for ethylene epoxidation, but with a low selectivity of <3%. Tests on pure Cu2O and CuO powders confirm that the oxides intrinsically exhibit partial-oxidation activity. Cu2O was found to form acetaldehyde and ethylene epoxide in roughly equal amounts (1.0% and 1.2% respectively), while CuO was found to form much less ethyl aldehyde than ethylene epoxide (0.1% and 1.0%, respectively). Metallic copper catalysts were examined in extreme dilute-O2 epoxidation conditions to try and keep the catalyst from oxidizing during the reaction. It was found that in feed of 1 part O2 to 2500 parts C2H4 (PO2 = 1.2 × 10(-4) mbar) the copper surface becomes O-terminated. The O-terminated surface was found to exhibit partial-oxidation selectivity similar to that of Cu2O. With increasing O2 concentration (>8/2500) Cu2O forms and eventually covers the surface.
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Heterogeneous chemical reactions at vapor/solid interfaces play an important role in many processes in the environment and technology. Ambient pressure X-ray photoelectron spectroscopy (APXPS) is a valuable tool to investigate the elemental composition and chemical specificity of surfaces and adsorbates on the molecular scale at pressures of up to 130 mbar. In this review we summarize the historical development of APXPS since its introduction over forty years ago, discuss different approaches to minimize scattering of electrons by gas molecules, and give a comprehensive overview about the experimental systems (vapor/solid interfaces) that have been studied so far. We also present several examples for the application of APXPS to environmental science, heterogeneous catalysis, and electrochemistry.
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Hydrogen peroxide (H2O2) is a widely used green oxidant. Until now, research has focused on the development of efficient catalysts for the two-electron oxygen reduction reaction (2e- ORR). However, electrolyte effects on the 2e- ORR have remained little understood. We report a significant effect of alkali metal cations (AMCs) on carbons in acidic environments. The presence of AMCs at a glassy carbon electrode shifts the half wave potential from -0.48 to -0.22 VRHE. This cation-induced enhancement effect exhibits a uniquely sensitive on/off switching behavior depending on the voltammetric protocol. Voltammetric and in situ X-ray photoemission spectroscopic evidence is presented, supporting a controlling role of the potential of zero charge of the catalytic enhancement. Density functional theory calculations associate the enhancement with stabilization of the *OOH key intermediate as a result of locally induced field effects from the AMCs. Finally, we developed a refined reaction mechanism for the H2O2 production in the presence of AMCs.
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BACKGROUND: During the UVA-cross-linking treatment in keratoconus patients, the UVA rays are partially absorbed in the stroma of the riboflavin-loaded cornea. This effect protects the corneal endothelium from UVA irradiation damage. The intensity of UVA light reaching the endothelium is inversely correlated with corneal thickness. The common composition of riboflavin eye drops may lead to a marked reduction in corneal thickness increasing the risk of endothelial damage. PATIENTS AND METHODS: In a retrospective analysis of 23 UVA-cross-linking procedures on 23 patients we collected data about the pre-, intra- and postoperative corneal thickness (measured with ultrasound). Among these patients and depending on the preoperative state, 8 eyes received Medio Cross (TM) eye drops (group 1), 8 eyes received Medio Cross (TM) eye drops combined with riboflavin 0.1 %/methylhydroxypropylcellulose 1,5 %/NaCl 1.1 % (group 2) and 7 eyes received riboflavin 0.2 %/methylhydroxypropylcellulose 0.5 %/NaCl 0.7 % eye drops (group 3) before and during UVA irradiation. Data are presented as means ± standard deviation. A comparison of the data was performed using (one-way) ANOVA. RESULTS: The mean corneal thickness at the end of the UVA cross-linking procedure was 67 ± 9 % (means ± standard deviation) of preoperative thickness in group 1, 118 ± 14 % in group 2 and 140 ± 23 % in group 3. The values in groups 2 and 3 were significantly different from those in the reference group 1. CONCLUSIONS: Our results show a strong variability of the postoperative corneal thickness using different standard compositions of riboflavin eye drops. Further studies are needed to find a composition of riboflavin eye drops ensuring a moderate increase in intraoperative corneal thickness to protect the corneal endothelium.
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Córnea/efectos de los fármacos , Córnea/fisiopatología , Queratocono/tratamiento farmacológico , Queratocono/fisiopatología , Riboflavina/administración & dosificación , Adulto , Relación Dosis-Respuesta a Droga , Composición de Medicamentos , Femenino , Humanos , Cuidados Intraoperatorios/métodos , Masculino , Soluciones Oftálmicas , Fotoquimioterapia/métodos , Fármacos Fotosensibilizantes/administración & dosificación , Resultado del Tratamiento , Rayos UltravioletaRESUMEN
Chronic exposure of retinal endothelium cells to hyperglycemia is the leading cause of diabetic retinopathy. We evaluated the effect of high glucose concentration on senescence in human retinal endothelial cells (HREC) and modulation of that effect by Sulodexide. Experiments were performed on HREC undergoing in vitro replicative senescence in standard medium or medium supplemented with glucose 20 mmol/L (GLU) or mannitol 20 mnol/L (MAN). Effect of Sulodexide 0.5 LRU/mL (SUL) on the process of HREC senescence was studied. Glucose 20 mmol/L accelerates senescence of HREC: population doubling time (+ 58%, p < 0.001) ß-galactosidase activity (+ 60%, p < 0.002) intracellular oxidative stress (+ 65%, p < 0.01), expression of p53 gene (+ 118%, p < 0.001). Senescent HREC had also reduced transendothelial electrical resistance (TEER) (- 30%, p < 0.001). Mannitol 20 mmol/L used in the same scenario as glucose did not induce HREC senescence. In HREC exposed to GLU and SUL, the senescent changes were smaller. HREC, which became senescent in the presence of GLU, demonstrated higher expression of genes regulating the synthesis of Il6 and VEGF-A, which was reflected by increased secretion of these cytokines (IL6 + 125%, p < 0.001 vs control and VEGF-A + 124% p < 0.001 vs control). These effects were smaller in the presence of SUL, and additionally, an increase of TEER in the senescent HREC was observed. Chronic exposure of HREC to high glucose concentration in medium accelerates their senescence, and that process is reduced when the cells are simultaneously exposed to Sulodexide. Additionally, Sulodexide decreases the secretion of IL6 and VEGF-A from senescent HREC and increases their TEER.
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Senescencia Celular/efectos de los fármacos , Células Endoteliales/metabolismo , Glucosa/farmacología , Glicosaminoglicanos/farmacología , Vasos Retinianos/metabolismo , Línea Celular , Regulación de la Expresión Génica/efectos de los fármacos , Humanos , Interleucina-6/biosíntesis , Potenciales de la Membrana/efectos de los fármacos , Factor A de Crecimiento Endotelial Vascular/biosíntesisRESUMEN
The Sicca-Förderpreis (Dry Eye Award) supports the development of scientific research on the pathogenesis, diagnostics, and treatment of dry eye and ocular surface diseases. It is awarded after a limited call for proposals in German-speaking countries, written application and selection of the award winner after evaluation by a jury of ophthalmologists working in basic and clinical science. In this article examples of the results of funded projects of the Sicca-Förderpreis 2016 are cursorily described, which were presented at the Ophthalmological Academy of Germany 2019 (Augenärztliche Akademie Deutschland 2019) and therefore provide an insight into current scientific developments. The role of muscarinic receptors and those of urea in the pathogenesis of dry eye as well as the (missing) correlation of tear film stability, viscosity and surface tension are highlighted. A project on the early detection of ocular involvement in graft versus host disease and the idea of treating meibomian gland dysfunction with eyelid surgery techniques are also groundbreaking. The outlined projects represent the potential for further substantial developments in the understanding, diagnostics and treatment of dry eye; however, their long-term clinical relevance still needs to be established.
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Distinciones y Premios , Síndromes de Ojo Seco , Enfermedades de los Párpados , Síndromes de Ojo Seco/diagnóstico , Síndromes de Ojo Seco/terapia , Alemania , Humanos , Glándulas Tarsales , LágrimasRESUMEN
Post-synthesis treatment of bimetallic catalysts in different gas phases resulting in the adsorption-induced segregation is among promising approaches to enhance their activity not compromising selectivity towards a number of low-temperature reactions. Our recently published paper (M.A. Panafidin, A.V. Bukhtiyarov, I.P. Prosvirin, I.A. Chetyrin, A.Yu. Klyushin, A. Knop-Gericke, N.S. Smirnova, P.V. Markov, I.S. Mashkovsky, Y.V. Zubavichus, A.Yu. Stakheev, V.I. Bukhtiyarov, A mild post-synthesis oxidative treatment of Pd-In/HOPG bimetallic catalysts as a tool of their surface structure fine tuning. Appl. Surf. Sci.) reports on Pd-In intermetallic formation regularities and their evolution after storage in air as well as during treatment in oxygen at submillibar pressures. The current paper gives an extended representation of experimental ex situ/in situ synchrotron-based photoelectron spectroscopy (SRPES) and scanning tunnelling microscopy (STM) data used to derive scientific conclusions in the paper quoted above.
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We present a case of a toxic reaction in both eyes caused by secretions from an encrusting anemone of the genus Protopalythoa. The patient presented with chemosis and follicular reaction of the conjunctiva and whitish spots on the limbus. Under local treatment with steroids and antibiotic eyedrops, remission was achieved within a few days. Palytoxin, a poisonous component of Protopalythoa secretions, leads to inhibition of the sodium-potassium-ATPase, to destabilization of the membrane potential and to cell death. Ocular exposure can lead to severe anatomical and functional impairments with systemic symptoms.
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Anemone , Quemaduras Químicas , Enfermedades de la Conjuntiva , Quemaduras Oculares , Conjuntiva , HumanosRESUMEN
Self-injurious behavior (nonsuicidal self-injury, NNSI) is a common phenomenon and occurs in Germany, especially in adolescence, with a lifetime prevalence of 25-35%. In adulthood autoaggressive behavior is usually associated with mental illness, such as borderline personality disorder, as in the presented case. Eye injuries are rare. The treating physician is faced with the difficulty of correctly classifying the injury and clarifying suicidal intentions. Patient care requires a lot of patience, empathy and time and has to include psychosocial aspects.
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Trastorno de Personalidad Limítrofe , Lesiones Oculares , Conducta Autodestructiva , Alemania , HumanosRESUMEN
Recent data suggest neurodermatitis as a risk factor for ocular surface squamous neoplasia (OSSN). We describe two cases of bilateral OSSN associated with chronic atopic keratoconjunctivitis. The cases support the hypothesis that neurodermatitis is a risk factor for OSSN. Additional risk factors may facilitate development and progression of the disease.
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Carcinoma de Células Escamosas/diagnóstico , Neoplasias de la Conjuntiva/diagnóstico , Queratoconjuntivitis/complicaciones , Neoplasias Primarias Múltiples/diagnóstico , Neurodermatitis/complicaciones , Adulto , Antibióticos Antineoplásicos/administración & dosificación , Apósitos Biológicos , Carcinoma de Células Escamosas/patología , Carcinoma de Células Escamosas/cirugía , Quimioterapia Adyuvante , Terapia Combinada , Neoplasias de la Conjuntiva/patología , Neoplasias de la Conjuntiva/cirugía , Humanos , Masculino , Persona de Mediana Edad , Mitomicina/administración & dosificación , Recurrencia Local de Neoplasia/diagnóstico , Recurrencia Local de Neoplasia/patología , Recurrencia Local de Neoplasia/cirugía , Neoplasias Primarias Múltiples/patología , Neoplasias Primarias Múltiples/cirugía , Soluciones Oftálmicas , ReoperaciónRESUMEN
The two presented case examples demonstrate that scleral perforation through highly accelerated, seemingly harmless confetti particles is possible. In addition to penetrating injuries that should be treated directly, contusions with serious consequential complications can also occur. A careful assessment and examination are essential to promptly provide the patient with the right treatment and to minimize complications.
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Contusiones , Lesiones Oculares , Humanos , EscleróticaRESUMEN
This case report describes a diagnostic chain in a patient with atypical bilateral corneal opacity, which led to the diagnosis of a hematological disorder. The patient's medical history, clinical appearance and findings in confocal microscopy gave rise to the suspicion of a paraproteinemic keratopathy. The hematological laboratory diagnostics revealed a monoclonal gammopathy of the IgG kappa type. The bone marrow puncture led to the diagnosis of a lymphoplasmacytic lymphoma, which belongs to the group of Bcell non-Hodgkin's lymphomas. This case demonstrates that paraproteinemic keratopathy can be associated with potentially life-threatening hematological diseases.
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Opacidad de la Córnea , Paraproteinemias , Córnea , Opacidad de la Córnea/cirugía , Humanos , Derivación y ConsultaRESUMEN
PURPOSE: To report on a case of recurrence of paraproteinemic keratopathy (PPK) associated with monoclonal gammopathy after bilateral penetrating keratoplasty. OBSERVATIONS: Penetrating keratoplasty was performed on both eyes of a 45-year-old man due to bilateral progressive corneal stromal clouding. Recurrence of the corneal stromal opacities accompanied by a decrease in visual acuity was observed on slit-lamp examination already two years after penetrating keratoplasty. Confocal laser scanning microscopy (CLSM) of the corneal grafts performed three years after penetrating keratoplasty showed bilateral morphological changes identical to that found in the patient's corneas prior to penetrating keratoplasty. A hematological work-up revealed monoclonal gammopathy of type IgG kappa. The histochemical examination of the explanted corneas confirmed the diagnosis of PPK. CONCLUSIONS AND IMPORTANCE: Paraproteinemic keratopathy is an underdiagnosed ophthalmological condition, which may be associated with potentially life-threatening hematologic disorders. A hematological workup should be performed in patients with corneal opacities of uncertain etiology. Penetrating keratoplasty should be performed with caution in patients with monoclonal gammopathy due to the possibility of a very fast recurrence of PPK in the corneal graft. This is the first presentation of the recurrence of flake-like PPK after penetrating keratoplasty assessed with CLSM.
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Due to the need of sustainable energy sources, methane dry reforming is a useful reaction for conversion of the greenhouse gases CH4 and CO2 to synthesis gas (CO + H2). Syngas is the basis for a wide range of commodity chemicals and can be utilized for fuel production via Fischer-Tropsch synthesis. The current study focuses on spectroscopic investigations of the surface and reaction properties of a ZrO2/Pt inverse model catalyst, i.e. ZrO2 particles (islands) grown on a Pt(1 1 1) single crystal, with emphasis on in situ near ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) during MDR reaction. In comparison to technological systems, model catalysts facilitate characterization of the surface (oxidation) state, surface adsorbates, and the role of the metal-support interface. Using XPS and infrared reflection absorption spectroscopy we demonstrated that under reducing conditions (UHV or CH4) the ZrO2 particles transformed to an ultrathin ZrO2 film that started to cover (wet) the Pt surface in an SMSI-like fashion, paralleled by a decrease in surface/interface oxygen. In contrast, (more oxidizing) dry reforming conditions with a 1:1 ratio of CH4 and CO2 were stabilizing the ZrO2 particles on the model catalyst surface (or were even reversing the strong metal support interaction (SMSI) effect), as revealed by in situ XPS. Carbon deposits resulting from CH4 dissociation were easily removed by CO2 or by switching to dry reforming conditions (673-873 K). Thus, at these temperatures the active Pt surface remained free of carbon deposits, also preserving the ZrO2/Pt interface.
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Alloying provides a means by which to tune a metal catalyst's electronic structure and thus tailor its performance; however, mean-field behaviour in metals imposes limits. To access unprecedented catalytic behaviour, materials must exhibit emergent properties that are not simply interpolations of the constituent components' properties. Here we show an emergent electronic structure in single-atom alloys, whereby weak wavefunction mixing between minority and majority elements results in a free-atom-like electronic structure on the minority element. This unusual electronic structure alters the minority element's adsorption properties such that the bonding with adsorbates resembles the bonding in molecular metal complexes. We demonstrate this phenomenon with AgCu alloys, dilute in Cu, where the Cu d states are nearly unperturbed from their free-atom state. In situ electron spectroscopy demonstrates that this unusual electronic structure persists in reaction conditions and exhibits a 0.1 eV smaller activation barrier than bulk Cu in methanol reforming. Theory predicts that several other dilute alloys exhibit this phenomenon, which offers a design approach that may lead to alloys with unprecedented catalytic properties.
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The selective hydrogenation of propyne over a Pd-black model catalyst was investigated under operando conditions at 1 bar making use of advanced X-ray diffraction (bulk sensitive) and photo-electron spectroscopy (surface sensitive) techniques. It was found that the population of subsurface species controls the selective catalytic semi-hydrogenation of propyne to propylene due to the formation of surface and near-surface PdCx that inhibits the participation of more reactive bulk hydrogen in the hydrogenation reaction. However, increasing the partial pressure of hydrogen reduces the population of PdCx with the concomitant formation of a ß-PdHx phase up to the surface, which is accompanied by a lattice expansion, allowing the participation of more active bulk hydrogen which is responsible for the unselective total alkyne hydrogenation. Therefore, controlling the surface and subsurface catalyst chemistry is crucial to control the selective alkyne semi-hydrogenation.