Photochemical versus Thermal Synthesis of Cobalt Oxyhydroxide Nanocrystals

Photochemical methods facilitate the generation, isolation, and study of metastable nanomaterials having unusual size, composition, and morphology. These harder-to-isolate and highly reactive phases, inaccessible using conventional high-temperature pyrolysis, are likely to possess enhanced and unprecedented chemical, electromagnetic, and catalytic properties. We report a fast, low-temperature and scalable photochemical route to synthesize very small (~3 nm) monodisperse cobalt oxyhydroxide (Co(O)OH) nanocrystals. This method uses readily and commercially available pentaamminechlorocobalt(III) chloride, [Co(NH3) 5Cl]Cl2, under acidic or neutral pH and proceeds under either near-UV (350 nm) or Vis (575 nm) illumination. Control experiments showed that the reaction proceeds at competent rates only in the presence of light, does not involve a free radical mechanism, is insensitive to O 2, and proceeds in two steps: (1) Aquation of [Co(NH3) 5Cl] 2+ to yield [Co(NH3) 5(H2O)] 3+, followed by (2) slow photoinduced release of NH3 from the aqua complex. This reaction is slow enough for Co(O)OH to form but fast enough so that nanocrystals are small (ca. 3 nm). The alternative dark thermal reaction proceeds much more slowly and produces much larger (~250 nm) polydisperse Co(O)OH aggregates. UV-Vis absorption measurements and ab initio calculations yield a Co(O)OH band gap of 1.7 eV. Fast thermal annealing of Co(O)OH nanocrystals leads to Co3O4 nanocrystals with overall retention of nanoparticle size and morphology. Thermogravimetric analysis shows that oxyhydroxide to mixed-oxide phase transition occurs at significantly lower temperatures (up to T = 64 degrees C) for small nanocrystals compared with the bulk

L'ostéopétrose récessive maligne et la fonction de l'ostéoclaste (à propos d'un cas)

LILLE2-BU Santé-Recherche (593502101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Direct Low-Temperature Deposition of Crystallized CoOOH Films by Potentiostatic Electrolysis.

Cobalt oxide films were deposited onto nickel electrodes from 25 up to 90°C at a constant potential of 0.5 V vs. SCE from a pH 7.4 nitrate solution containing Co(II). Above 60°C, scanning electron microscopy and X-ray diffraction (XRD) experiments reveal that the films are constituted of crystallized grains. At 90°C the crystallite size is measured at ca. 34 nm. XRD experiments show that the crystallized product is composed of CoOOH, and Raman spectroscopy shows the formation of this compound between 40 and 90°C. Between room temperature and 90°C, the deposition rate is increased by an order of magnitude and the deposit crystallization has a favorable effect on the faradaic deposition efficiency. It may also favor the mechanical stability in temperature of this deposit when used as cobalt oxide-based protective coating of the molten carbonate fuel cell nickel cathode

Gastrointestinal: Ano-popliteal fistula in Crohn's disease

International audienc

Avaliação dos efeitos adversos clínicos e alterações laboratoriais em pacientes com acne vulgar tratados com isotretinoína oral Evaluation of clinical adverse effects and laboratory alterations in patients with acne vulgaris treated with oral isotretinoin

FUNDAMENTOS: A isotretinoína oral revolucionou o manejo da acne. Os efeitos adversos observados, durante o tratamento, são divididos em dois grupos: mucocutâneos e sistêmicos. Anormalidades laboratoriais, principalmente, as dislipidemias e aumento das enzimas hepáticas são relatados. OBJETIVO: Avaliar a tolerabilidade da isotretinoína oral, com atenção, no metabolismo lipídico, função hepática e reações adversas clínicas. MÉTODOS: Foram incluídos 150 pacientes com diagnóstico clínico de acne submetidos a tratamento com isotretinoína oral. Avaliações clínicas e laboratoriais foram feitas, após um mês e a cada três meses, até completar o tratamento. RESULTADOS: Dos 150 pacientes 48% eram do sexo feminino e 52% do sexo masculino. A idade variou de 15 a 32 anos. Quanto aos efeitos adversos cutâneos e mucosos da isotretinoína, queilite foi o mais frequente, ocorrendo em 94% pacientes. Efeitos clínicos sistêmicos foram bem menos comuns. Os níveis de colesterol, triglicerídeos, transaminases, foram avaliados e não mostraram alterações significativas, ao longo do tratamento. CONCLUSÃO: Os pacientes apresentaram efeitos adversos, compatíveis com os da literatura, e, em sua maioria, controlados com medicações sintomáticas. Podemos concluir que a isotretinoína é uma droga segura, em relação a seus efeitos adversos, tanto clínicos como laboratoriais.<br>BACKGROUND: Oral isotretinoin therapy has completely changed the treatment of acne. The clinical adverse effects of isotretinoin are classified into two groups: mucocutaneous and systemic toxic. Laboratory alterations such as dyslipidemia and increase of hepatic enzymes are reported. OBJECTIVES: To evaluate the tolerability of oral isotretinoin with special attention to lipid metabolism, hepatic function, and clinical adverse reactions. METHODS: 150 patients clinically diagnosed with acne being treated with oral isotretinoin were included in the study. Clinical and laboratory evaluations were conducted before the start of therapy, one month after, and every three months thereafter until the completion of treatment. RESULTS: Of the 150 patients evaluated, 48% were female and 52%, male. They were aged from 15 to 32 years. The most prevalent mucocutaneous adverse reaction associated with isotretinoin therapy was cheilitis, reported by 94% of the patients. Systemic clinical effects were much less common. Cholesterol, triglyceride, and transaminase levels were assessed and significant changes were not observed during treatment. CONCLUSION: Patients showed adverse effects compatible to those described in the literature, which are mostly controlled with symptomatic medication. Isotretinoin is a safe drug and adverse and laboratory effects are well tolerated