Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 102
Filtrar
Mais filtros

Intervalo de ano de publicação
1.
Nature ; 562(7725): 82-85, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-30283106

RESUMO

SS 433 is a binary system containing a supergiant star that is overflowing its Roche lobe with matter accreting onto a compact object (either a black hole or neutron star)1-3. Two jets of ionized matter with a bulk velocity of approximately 0.26c (where c is the speed of light in vacuum) extend from the binary, perpendicular to the line of sight, and terminate inside W50, a supernova remnant that is being distorted by the jets2,4-8. SS 433 differs from other microquasars (small-scale versions of quasars that are present within our own Galaxy) in that the accretion is believed to be super-Eddington9-11, and the luminosity of the system is about 1040 ergs per second2,9,12,13. The lobes of W50 in which the jets terminate, about 40 parsecs from the central source, are expected to accelerate charged particles, and indeed radio and X-ray emission consistent with electron synchrotron emission in a magnetic field have been observed14-16. At higher energies (greater than 100 gigaelectronvolts), the particle fluxes of γ-rays from X-ray hotspots around SS 433 have been reported as flux upper limits6,17-20. In this energy regime, it has been unclear whether the emission is dominated by electrons that are interacting with photons from the cosmic microwave background through inverse-Compton scattering or by protons that are interacting with the ambient gas. Here we report teraelectronvolt γ-ray observations of the SS 433/W50 system that spatially resolve the lobes. The teraelectronvolt emission is localized to structures in the lobes, far from the centre of the system where the jets are formed. We have measured photon energies of at least 25 teraelectronvolts, and these are certainly not Doppler-boosted, because of the viewing geometry. We conclude that the emission-from radio to teraelectronvolt energies-is consistent with a single population of electrons with energies extending to at least hundreds of teraelectronvolts in a magnetic field of about 16 microgauss.

3.
Environ Res ; 249: 118388, 2024 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-38331149

RESUMO

Nowadays, the scarcity of energy resources is promoting the search for alternative energy sources, boosting interest in the use of forest lignocellulosic residue in the energy sector. In this study, the focus is on the energy recovery from two lignocellulosic residues originated during the pruning of ornamental trees (Horse Chestnut, CI, and False Acacia, FA). Both conventional and flash pyrolysis techniques were applied. The experimental pyrolysis variables were obtained from the study of the thermal behaviour of the pruning residues in thermogravimetric analysis. It was carried out under 5 heating rates and kinetic parameters were estimated using Flynn-Wall-Ozawa method. Results denoted higher maximum mass loss rate values for the same release temperature regions under FA experiments. Also, FA samples had lower final residues for the processes. However, activation energy values were so close for both species. FA was also linked to the faster reactions according frequency factor outcomes. Conventional pyrolysis of pruning residues was carried out in a horizontal oven of original design at a heating rate of 25 °C/min, at 750 °C and 60 min of permanence at that temperature; flash pyrolysis was tested in that oven at 750 and 850 °C. In these pyrolysis processes, three fractions were obtained: bio-char, bio-oil and gas. The physicochemical attributes of the bio-chars suggested their potential utility as biofuels (28.4-29.8 MJ/kg), adsorbent precursors or soil additives. Conventional pyrolysis bio-oils had a dominant monoaromatic hydrocarbons nature, with phenols being the most abundant (≥60%), while flash bio-oils contain mainly polycyclic aromatic hydrocarbons. Conventional pyrolysis gases contained up to 60 vol% of CO2; flash pyrolysis gases had high combustible gas content (CO, CH4, H2) and a low CO2 content (<25 vol%). As a result, their calorific value (18.06 MJ/kg) exhibited a threefold increase compared to the gas produced through conventional pyrolysis (6.04 MJ/kg).


Assuntos
Biocombustíveis , Biomassa , Pirólise , Biocombustíveis/análise , Acacia/química , Corylus/química , Termogravimetria , Árvores
4.
Actas Dermosifiliogr ; 2024 May 31.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-38823769

RESUMO

After the meeting held by the Spanish Contact Dermatitis and Skin Allergy Research Group (GEIDAC) back in October 2021, changes were suggested to the Spanish Standard Series patch testing. Hydroxyethyl methacrylate (2% pet.), textile dye mixt (6.6% pet.), linalool hydroperoxide (1% pet.), and limonene hydroperoxide (0.3% pet.) were, then, added to the series that agreed upon in 2016. Ethyldiamine and phenoxyethanol were excluded. Methyldibromoglutaronitrile, the mixture of sesquiterpene lactones, and hydroxyisohexyl 3-cyclohexene (Lyral) were also added to the extended Spanish series of 2022.

5.
Actas Dermosifiliogr ; 115(7): 712-721, 2024.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-38556197

RESUMO

After the meeting held by the Spanish Contact Dermatitis and Skin Allergy Research Group (GEIDAC) back in October 2021, changes were suggested to the Spanish standard series patch testing. Hydroxyethyl methacrylate (2% pet.), textile dye mixt (6.6% pet.), linalool hydroperoxide (1% pet.), and limonene hydroperoxide (0.3% pet.) were, then, added to the series that agreed upon in 2016. Ethyldiamine and phenoxyethanol were excluded. Methyldibromoglutaronitrile, the mixture of sesquiterpene lactones, and hydroxyisohexyl 3-cyclohexene (Lyral) were alo added to the extended Spanish series of 2022.


Assuntos
Dermatite Alérgica de Contato , Testes do Emplastro , Humanos , Espanha , Dermatite Alérgica de Contato/diagnóstico , Dermatite Alérgica de Contato/etiologia , Alérgenos/efeitos adversos
6.
Phys Rev Lett ; 131(5): 051201, 2023 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-37595214

RESUMO

We report the first detection of a TeV γ-ray flux from the solar disk (6.3σ), based on 6.1 years of data from the High Altitude Water Cherenkov (HAWC) observatory. The 0.5-2.6 TeV spectrum is well fit by a power law, dN/dE=A(E/1 TeV)^{-γ}, with A=(1.6±0.3)×10^{-12} TeV^{-1} cm^{-2} s^{-1} and γ=3.62±0.14. The flux shows a strong indication of anticorrelation with solar activity. These results extend the bright, hard GeV emission from the disk observed with Fermi-LAT, seemingly due to hadronic Galactic cosmic rays showering on nuclei in the solar atmosphere. However, current theoretical models are unable to explain the details of how solar magnetic fields shape these interactions. HAWC's TeV detection thus deepens the mysteries of the solar-disk emission.

7.
J Environ Manage ; 312: 114897, 2022 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-35334399

RESUMO

Bio-derived magnetic activated carbons from industrial chestnut shell waste have been obtained through a novel, optimized and sustainable methodology where impregnation, pyrolysis, acid washing or other intermediate steps commonly used in the activation process were eliminated saving time, energy and costs. The resulting materials (MACs) were obtained at 220-800 °C showed interesting properties: textural (SBET up to 568 m2 g-1) and magnetic (different iron species developed), depending on the activation temperature employed. Data showed outstanding results when MACs were tested for Hg removal in pollution emissions at 150 °C in lab-scale device. In MACs obtained at 500-600 °C, where the highest concentration of magnetite was found, the best Hg adsorption capacity was achieved, while it decreased when metallic iron or iron carbides were present (MACs obtained at 800 °C). Moreover, the difference of Hg0 removal/adsorption in N2+O2 and Simulated Flue Gas atmosphere between MACs obtained at 500 and 600 °C pointed out the influence on Hg removal of additional parameters, as surface chemistry and the existence of sulfur or chloride. The determination of Hg species in post-retention solids confirmed the mercury oxidation by high-valence iron ions (Fe3+) and the involvement of physisorption and chemisorption processes for the gas-solid interaction mechanism.


Assuntos
Poluentes Atmosféricos , Mercúrio , Adsorção , Poluentes Atmosféricos/análise , Carvão Vegetal , Resíduos Industriais , Ferro , Fenômenos Magnéticos , Mercúrio/análise
8.
Phys Rev Lett ; 124(13): 131101, 2020 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-32302173

RESUMO

Because of the high energies and long distances to the sources, astrophysical observations provide a unique opportunity to test possible signatures of Lorentz invariance violation (LIV). Superluminal LIV enables the decay of photons at high energy. The high altitude water Cherenkov (HAWC) observatory is among the most sensitive gamma-ray instruments currently operating above 10 TeV. HAWC finds evidence of 100 TeV photon emission from at least four astrophysical sources. These observations exclude, for the strongest of the limits set, the LIV energy scale to 2.2×10^{31} eV, over 1800 times the Planck energy and an improvement of 1 to 2 orders of magnitude over previous limits.

9.
Phys Rev Lett ; 124(2): 021102, 2020 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-32004015

RESUMO

We present the first catalog of gamma-ray sources emitting above 56 and 100 TeV with data from the High Altitude Water Cherenkov Observatory, a wide field-of-view observatory capable of detecting gamma rays up to a few hundred TeV. Nine sources are observed above 56 TeV, all of which are likely galactic in origin. Three sources continue emitting past 100 TeV, making this the highest-energy gamma-ray source catalog to date. We report the integral flux of each of these objects. We also report spectra for three highest-energy sources and discuss the possibility that they are PeVatrons.

13.
Actas Dermosifiliogr ; 106(4): 278-84, 2015 May.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-25708653

RESUMO

Atopic dermatitis has become a health problem in our setting due to its rising prevalence, impact on quality of life, associated costs, and role in the progression to other atopic diseases. Furthermore, atopic dermatitis has no definitive cure and therefore preventive measures are important. In this article, we review the latest advances in both primary prevention (reduction of the incidence of atopic dermatitis) and secondary prevention (reduction of associated morbidity and reduction of the atopic march). We analyze the different preventive strategies available, including modification of the immune system through microbial exposure, induction of immune tolerance through antigen exposure, and restoration of skin barrier function to halt the atopic march. Dermatologists need to be familiar with these strategies in order to apply them where necessary and to accurately inform patients and their relatives to prevent misguided or inappropriate actions.


Assuntos
Dermatite Atópica/prevenção & controle , Animais , Animais Domésticos , Antibacterianos/uso terapêutico , Antígenos/uso terapêutico , Terapia Biológica , Aleitamento Materno , Ensaios Clínicos como Assunto , Dermatite Atópica/dietoterapia , Dermatite Atópica/etiologia , Dessensibilização Imunológica , Poeira , Exposição Ambiental , Medicina Baseada em Evidências , Helmintíase/imunologia , Humanos , Tolerância Imunológica , Metanálise como Assunto , Prebióticos , Prevenção Primária/métodos , Probióticos , Prevenção Secundária/métodos
14.
Appl Microbiol Biotechnol ; 96(2): 327-44, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22903276

RESUMO

The use of enzymes has a high potential in the pulp and paper industry to improve the economics of the paper production process and to achieve, at the same time, a reduced environmental impact. Specific enzymes contribute to reduce the amount of chemicals and energy required for the modification of fibers and helps to prevent the formation or development of biofilms. This review is aimed at presenting the latest progresses made in the application of enzymes as refining aids and biofilm control agents.


Assuntos
Biofilmes , Biotecnologia/métodos , Enzimas/química , Proteínas Fúngicas/química , Fungos/enzimologia , Fungos/fisiologia , Madeira/química , Celulose/química , Enzimas/metabolismo , Proteínas Fúngicas/metabolismo , Indústrias , Papel , Madeira/microbiologia
15.
Actas Dermosifiliogr ; 103(5): 427-31, 2012 Jun.
Artigo em Espanhol | MEDLINE | ID: mdl-21885023

RESUMO

Marginal zone B-cell lymphoma (MZL) is subclassified into extranodal MZL of mucosa-associated lymphoid tissue (including cutaneous lymphomas), splenic MZL, and nodal MZL. We report the case of a 68-year-old man with erythematous-violaceous plaques and nodules. Skin biopsy showed an epidermotropic lymphocytic infiltration and cytology and immunohistochemistry were consistent with MZL. The workup revealed disease in the peripheral blood and bone marrow and massive splenomegaly. Splenectomy confirmed the diagnosis of splenic MZL and led to resolution of the skin lesions. Cutaneous recurrence was treated successfully with chemotherapy and rituximab but caused fatal hepatitis due to hepatitis B virus reactivation. Skin involvement by splenic MZL is uncommon; this form of the disease can present epidermotropism, a very rare finding in primary cutaneous MZL. Treatment consists of splenectomy, which may be associated with chemotherapy and/or rituximab; this treatment may lead to reactivation of latent hepatitis B infection and screening for hepatitis should therefore be performed prior to starting therapy.


Assuntos
Linfoma de Zona Marginal Tipo Células B/patologia , Neoplasias Cutâneas/patologia , Neoplasias Esplênicas/patologia , Idoso , Humanos , Masculino , Metástase Neoplásica
16.
Actas Dermosifiliogr ; 102(9): 717-21, 2011 Nov.
Artigo em Espanhol | MEDLINE | ID: mdl-21596362

RESUMO

BACKGROUND AND OBJECTIVES: Treatment of mucosal vascular lesions is a challenge for dermatologists, although various approaches have proven efficacy, including surgery, sclerotherapy, intralesional injection of corticosteroids, transfixion, and laser therapy. The aim of this study was to describe the results of treatment with neodymium:yttrium-aluminum-garnet (Nd:YAG) laser in 11 patients with venous malformations and varicosities. PATIENTS AND METHODS: We describe the use of variable-pulse Nd:YAG to treat venous malformations or varicosities in the oral or genital mucosa of 8 women and 3 men seen in our hospital over a 1-year period. RESULTS: The following laser parameters were used: wavelength, 1064 nm; fluence, 100 to 200J/cm(2); spot diameter, 3 to 5mm; and pulse duration, 30 to 65 ms. The size of the lesions ranged from 5 to 30 mm. In all cases, a clearance of 75% to 100% was achieved in a single session with excellent healing and no significant side effects. CONCLUSIONS: Given its efficacy and ease of use, Nd:YAG may become a treatment of choice for mucosal vascular lesions. Comparative studies are now required to assess its potential superiority over other treatment options.


Assuntos
Terapia a Laser , Lasers de Estado Sólido/uso terapêutico , Malformações Vasculares/cirurgia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
17.
Clin Transl Oncol ; 23(7): 1474-1480, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33433837

RESUMO

BACKGROUND: Immune checkpoint inhibitors (ICI) have been associated with several immune-related adverse events, including sarcoidosis-like reactions (SLR). SLR, which has a low prevalence but an increasing incidence, is similar to sarcoidosis in terms of histology, and clinical and radiological manifestations. The most commonly affected organs are hilar and mediastinal lymph nodes and skin. SLR is an exclusion diagnosis, so a lymph node biopsy can be useful to distinguish between tumor progression and SLR, particularly in tumors in which nodal involvement is very common. PATIENTS AND METHODS: We performed a retrospective analysis of SLR in all cancer patients receiving ICIs in our institution between January 2016 and June 2020. RESULTS: Among the 1063 treated patients, seven experienced SLR, four of whom were symptomatic (cough, skin lesions, arthralgia), with time to onset ranging from 1.5 to 6.7 months after ICI initiation. All seven patients had bilateral hilar lymphadenopathy, and granulomatous reactions in five of the six patients with lymph node biopsies. SLR improved in all patients, including four patients who continued with ICI. Three patients received corticosteroids and/or stopped ICI therapy. Four of these patients had partial responses at the time SLR was identified. CONCLUSION: Management of SLR lacks a consensus recommendation, although corticosteroids and/or stopping the ICI are generally implemented. The potential consequences of stopping anticancer treatment should be taken into consideration, particularly in the absence of clear management recommendations.


Assuntos
Toxidermias/etiologia , Inibidores de Checkpoint Imunológico/efeitos adversos , Linfadenopatia/induzido quimicamente , Neoplasias/tratamento farmacológico , Sarcoidose/induzido quimicamente , Adulto , Idoso , Feminino , Hospitais , Humanos , Inibidores de Checkpoint Imunológico/uso terapêutico , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Espanha
19.
Ultrasonics ; 101: 106035, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31574368

RESUMO

The use of ultrasonic dental scaler (UDS) tips has been investigated for cleaning ceramic membranes fouled when filtering cactus juice. Thin and long tips having a larger coverage exhibited the best performance for removing the cake layer deposited on the membrane surface. Such tips cleaned an area equivalent to almost one third of total area of the membrane surface. However, the cleaned area could be increased notoriously if the membrane were placed in rotatory disc holder. The resistance-in series model and atomic force microscopy (AFM) technique helped to reveal the effect of the UDS tips as cleaning process of ceramic membranes. The reversible resistances estimated for UDS tips were 58% and 17% lower than the ones obtained by chemical cleaning at transmembrane pressures of 0.3 bar and 0.5 bar, respectively. This was corroborated by microscope images, which showed the detachment of cake layer of the membrane surface. Results of this work showed that UDS tips are an innovative option as cleaning strategy for filtration membranes.

20.
Semergen ; 46(4): 270-276, 2020.
Artigo em Espanhol | MEDLINE | ID: mdl-32044200

RESUMO

Urticaria is a common cause for patient consultations in Primary Care (PC). However, the optimal approach to managing urticaria in PC is controversial and not well-established. For this reason, there is a clear need to clarify the causes of urticaria and to develop treatment protocols to improve urticaria management in the PC setting. The present work has been developed with this objective. A group of experts in PC and dermatology, with specific expertise in treating urticaria, have reviewed the main clinical guidelines and publications on urticaria in order to develop clear, interdisciplinary recommendations on managing urticaria. In this article, consensus-based recommendations are presented that include simple, practical diagnostic, and treatment algorithms. These guidelines will help to optimise the management of patients with urticaria, increasing their quality of life and reducing the socioeconomic costs associated with this illness.


Assuntos
Urticária , Doença Crônica , Consenso , Humanos , Atenção Primária à Saúde , Qualidade de Vida , Encaminhamento e Consulta
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA