Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 6 de 6
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Nat Commun ; 15(1): 1208, 2024 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-38332035

RESUMO

Environmental humidity variations are ubiquitous and high humidity characterizes fuel cell and electrolyzer operation conditions. Since hydrogen-air mixtures are highly flammable, humidity tolerant H2 sensors are important from safety and process monitoring perspectives. Here, we report an optical nanoplasmonic hydrogen sensor operated at elevated temperature that combined with Deep Dense Neural Network or Transformer data treatment involving the entire spectral response of the sensor enables a 100 ppm H2 limit of detection in synthetic air at 80% relative humidity. This significantly exceeds the <1000 ppm US Department of Energy performance target. Furthermore, the sensors pass the ISO 26142:2010 stability requirement in 80% relative humidity in air down to 0.06% H2 and show no signs of performance loss after 140 h continuous operation. Our results thus demonstrate the potential of plasmonic hydrogen sensors for use in high humidity and how neural-network-based data treatment can significantly boost their performance.

2.
J Phys Chem B ; 125(14): 3700-3709, 2021 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-33818098

RESUMO

The polarity of all-cis-multifluorinated cyclohexanes can be fine-tuned by the number and relative orientation of fluoro substituents, giving rise to a series of compounds with strong dipole moments. Simulations provided the energetics, the dipole moments, and the respective molecular polarizabilities, while dielectric spectroscopy gave information on the dielectric permittivities and the molecular dynamics. In special cases, dipole moments in excess of 6 D and dielectric permittivities of over 300 were obtained by simulation and experiment. Melting temperatures within a given family of multifluorinated cyclohexanes were found to scale with the molecular volume. The less-symmetric all-cis-octafluorotetrahydronaphthalene did not readily crystallize, permitting an investigation of the molecular dynamics in an energetically unfavorable yet rigid and facially polarized isomer. The resulting dynamics above the glass temperature conform to the structural α-relaxation and to the celebrated Johari-Goldstein ß-relaxation.

3.
Clin Dermatol ; 37(4): 365-372, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31345325

RESUMO

Skin aging is a complex biologic process influenced by a combination of intrinsic and extrinsic factors. Aging skin shows wrinkles, uneven tone, loss of elasticity, and thinning. Skin health is considered one of the principal factors representing overall well-being and the perception of health in humans; therefore, anti-aging strategies to combat aging signs and dysfunction have been developed over the last decades. Understanding the mechanism behind skin aging is required for elucidation of the mechanism of action and, hence, the potential benefits of the claimed anti-aging products. In this review, preventive measurements, cosmetologic strategies, and photoprotection (systemic antioxidants, ultraviolet and filters), as well as the mechanisms of action and the effectiveness of topical pharmaceutical agents, such as antioxidants (vitamins, polyphenols, and flavonoids) and cell regulators (retinols, peptides, hormones, and botanicals), are presented.


Assuntos
Técnicas Cosméticas , Envelhecimento da Pele , Estética , Humanos
4.
Orphanet J Rare Dis ; 8: 10, 2013 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-23316694

RESUMO

UNLABELLED: DEFINITION OF THE DISEASE: Malignant atrophic papulosis (MAP), described independently by Köhlmeier and Degos et al., is a rare, chronic, thrombo-obliterative vasculopathy characterized by papular skin lesions with central porcelain-white atrophy and surrounding teleangiectatic rim. EPIDEMIOLOGY: Less than 200 cases have been described in the literature. The first manifestation of MAP usually occurs between the 20th and 50th year of life. CLINICAL DESCRIPTION: The cutaneous clinical picture is almost pathognomonic. The histology is not consistent but in most cases it shows a wedge-shaped connective tissue necrosis in the deep corium due to a thrombotic occlusion of the small arteries. In the systemic variant, manifestations mostly occur at the intestine and central nervous system. ETIOLOGY: The etiopathogenesis of the disease remains unknown, a genetic predisposition may occur. Vasculitis, coagulopathy or primary dysfunction of the endothelial cells have been implicated. DIAGNOSTIC METHODS: Diagnosis is only based on the characteristic skin lesions. DIFFERRENTIAL DIAGNOSIS: It depends on the clinical presentation of MAP, but systemic lupus erythematosus and other connective tissue diseases need to be considered. MANAGEMENT: No effective treatment exists for the systemic manifestations, while compounds that facilitate blood perfusion have achieved a partial regression of the skin lesions in single cases. PROGNOSIS: An apparently idiopathic, monosymptomatic, cutaneous, benign variant and a progressive, visceral one with approx. 50% lethality within 2-3 years have been reported. Systemic manifestations can develop years after the occurrence of skin lesions leading to bowel perforation and peritonitis, thrombosis of the cerebral arteries or massive intracerebral hemorrhage, meningitis, encephalitis, radiculopathy, myelitis.


Assuntos
Papulose Atrófica Maligna , Humanos , Imunossupressores/uso terapêutico , Papulose Atrófica Maligna/diagnóstico , Papulose Atrófica Maligna/tratamento farmacológico , Papulose Atrófica Maligna/patologia , Prognóstico
5.
Dermatoendocrinol ; 4(3): 308-19, 2012 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-23467476

RESUMO

Skin aging is a complex biological process influenced by a combination of endogenous or intrinsic and exogenous or extrinsic factors. Because of the fact that skin health and beauty is considered one of the principal factors representing overall "well-being" and the perception of "health" in humans, several anti-aging strategies have been developed during the last years. It is the intention of this article to review the most important anti-aging strategies that dermatologists have nowadays in hand, including including preventive measurements, cosmetological strategies, topical and systemic therapeutic agents and invasive procedures.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...