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1.
Science ; 367(6481)2020 02 28.
Artigo em Inglês | MEDLINE | ID: mdl-32054693

RESUMO

The outer Solar System object (486958) Arrokoth (provisional designation 2014 MU69) has been largely undisturbed since its formation. We studied its surface composition using data collected by the New Horizons spacecraft. Methanol ice is present along with organic material, which may have formed through irradiation of simple molecules. Water ice was not detected. This composition indicates hydrogenation of carbon monoxide-rich ice and/or energetic processing of methane condensed on water ice grains in the cold, outer edge of the early Solar System. There are only small regional variations in color and spectra across the surface, which suggests that Arrokoth formed from a homogeneous or well-mixed reservoir of solids. Microwave thermal emission from the winter night side is consistent with a mean brightness temperature of 29 ± 5 kelvin.

2.
Science ; 354(6319): 1563-1566, 2016 12 23.
Artigo em Inglês | MEDLINE | ID: mdl-27856846

RESUMO

Carbon dioxide (CO2) is one of the most abundant species in cometary nuclei, but because of its high volatility, CO2 ice is generally only found beneath the surface. We report the infrared spectroscopic identification of a CO2 ice-rich surface area located in the Anhur region of comet 67P/Churyumov-Gerasimenko. Spectral modeling shows that about 0.1% of the 80- by 60-meter area is CO2 ice. This exposed ice was observed a short time after the comet exited local winter; following the increased illumination, the CO2 ice completely disappeared over about 3 weeks. We estimate the mass of the sublimated CO2 ice and the depth of the eroded surface layer. We interpret the presence of CO2 ice as the result of the extreme seasonal changes induced by the rotation and orbit of the comet.

3.
Nature ; 539(7627): 65-68, 2016 11 03.
Artigo em Inglês | MEDLINE | ID: mdl-27626378

RESUMO

A unique feature of Pluto's large satellite Charon is its dark red northern polar cap. Similar colours on Pluto's surface have been attributed to tholin-like organic macromolecules produced by energetic radiation processing of hydrocarbons. The polar location on Charon implicates the temperature extremes that result from Charon's high obliquity and long seasons in the production of this material. The escape of Pluto's atmosphere provides a potential feedstock for a complex chemistry. Gas from Pluto that is transiently cold-trapped and processed at Charon's winter pole was proposed as an explanation for the dark coloration on the basis of an image of Charon's northern hemisphere, but not modelled quantitatively. Here we report images of the southern hemisphere illuminated by Pluto-shine and also images taken during the approach phase that show the northern polar cap over a range of longitudes. We model the surface thermal environment on Charon and the supply and temporary cold-trapping of material escaping from Pluto, as well as the photolytic processing of this material into more complex and less volatile molecules while cold-trapped. The model results are consistent with the proposed mechanism for producing the observed colour pattern on Charon.

4.
Science ; 351(6279): aad9189, 2016 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-26989260

RESUMO

The New Horizons spacecraft mapped colors and infrared spectra across the encounter hemispheres of Pluto and Charon. The volatile methane, carbon monoxide, and nitrogen ices that dominate Pluto's surface have complicated spatial distributions resulting from sublimation, condensation, and glacial flow acting over seasonal and geological time scales. Pluto's water ice "bedrock" was also mapped, with isolated outcrops occurring in a variety of settings. Pluto's surface exhibits complex regional color diversity associated with its distinct provinces. Charon's color pattern is simpler, dominated by neutral low latitudes and a reddish northern polar region. Charon's near-infrared spectra reveal highly localized areas with strong ammonia absorption tied to small craters with relatively fresh-appearing impact ejecta.

5.
Nature ; 529(7586): 368-72, 2016 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-26760209

RESUMO

Although water vapour is the main species observed in the coma of comet 67P/Churyumov-Gerasimenko and water is the major constituent of cometary nuclei, limited evidence for exposed water-ice regions on the surface of the nucleus has been found so far. The absence of large regions of exposed water ice seems a common finding on the surfaces of many of the comets observed so far. The nucleus of 67P/Churyumov-Gerasimenko appears to be fairly uniformly coated with dark, dehydrated, refractory and organic-rich material. Here we report the identification at infrared wavelengths of water ice on two debris falls in the Imhotep region of the nucleus. The ice has been exposed on the walls of elevated structures and at the base of the walls. A quantitative derivation of the abundance of ice in these regions indicates the presence of millimetre-sized pure water-ice grains, considerably larger than in all previous observations. Although micrometre-sized water-ice grains are the usual result of vapour recondensation in ice-free layers, the occurrence of millimetre-sized grains of pure ice as observed in the Imhotep debris falls is best explained by grain growth by vapour diffusion in ice-rich layers, or by sintering. As a consequence of these processes, the nucleus can develop an extended and complex coating in which the outer dehydrated crust is superimposed on layers enriched in water ice. The stratigraphy observed on 67P/Churyumov-Gerasimenko is therefore the result of evolutionary processes affecting the uppermost metres of the nucleus and does not necessarily require a global layering to have occurred at the time of the comet's formation.


Assuntos
Meio Ambiente Extraterreno/química , Gelo/análise , Meteoroides , Difusão , Gases/análise , Gases/química , Análise Espectral
6.
Nature ; 525(7570): 500-3, 2015 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-26399830

RESUMO

Observations of cometary nuclei have revealed a very limited amount of surface water ice, which is insufficient to explain the observed water outgassing. This was clearly demonstrated on comet 9P/Tempel 1, where the dust jets (driven by volatiles) were only partially correlated with the exposed ice regions. The observations of 67P/Churyumov-Gerasimenko have revealed that activity has a diurnal variation in intensity arising from changing insolation conditions. It was previously concluded that water vapour was generated in ice-rich subsurface layers with a transport mechanism linked to solar illumination, but that has not hitherto been observed. Periodic condensations of water vapour very close to, or on, the surface were suggested to explain short-lived outbursts seen near sunrise on comet 9P/Tempel 1. Here we report observations of water ice on the surface of comet 67P/Churyumov-Gerasimenko, appearing and disappearing in a cyclic pattern that follows local illumination conditions, providing a source of localized activity. This water cycle appears to be an important process in the evolution of the comet, leading to cyclical modification of the relative abundance of water ice on its surface.


Assuntos
Meio Ambiente Extraterreno/química , Gelo/análise , Meteoroides , Temperatura , Fatores de Tempo , Volatilização
7.
Science ; 347(6220): aaa0628, 2015 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-25613895

RESUMO

The VIRTIS (Visible, Infrared and Thermal Imaging Spectrometer) instrument on board the Rosetta spacecraft has provided evidence of carbon-bearing compounds on the nucleus of the comet 67P/Churyumov-Gerasimenko. The very low reflectance of the nucleus (normal albedo of 0.060 ± 0.003 at 0.55 micrometers), the spectral slopes in visible and infrared ranges (5 to 25 and 1.5 to 5% kÅ(-1)), and the broad absorption feature in the 2.9-to-3.6-micrometer range present across the entire illuminated surface are compatible with opaque minerals associated with nonvolatile organic macromolecular materials: a complex mixture of various types of carbon-hydrogen and/or oxygen-hydrogen chemical groups, with little contribution of nitrogen-hydrogen groups. In active areas, the changes in spectral slope and absorption feature width may suggest small amounts of water-ice. However, no ice-rich patches are observed, indicating a generally dehydrated nature for the surface currently illuminated by the Sun.

8.
Minerva Ginecol ; 64(5): 431-5, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23018482

RESUMO

AIM: The aim of this paper was to determine the activity of a natural nutraceuticals combination (AP=Berberine+Red Yeast Rice) on dyslipidemia which frequently persists after life style changes in patients on hormone-therapy following breast cancer (HT-BC). METHODS: Twenty-one HT-BC patients, free of tumor, mean age 59.9 years, BMI 28,9 kg/m2, waist circumference 95.9 cm, with altered lipid profile (total cholesterol 269.0 mg/dL, high-density lipoprotein (HDL) cholesterol 54.9 mg/dL, low-density lipoprotein (LDL) cholesterol 184.0 mg/dL, and triglycerides 263.3 mg/dL) were recruited. They were recommended a 3-month period of diet followed by a 3-month period of treatment with AP 1 tablet/day. AP tablets contain berberine 500 mg, red yeast rice extract 200 mg (equivalent to 3 mg monacolins), policosanol 10 mg, folic acid 0.2 mg, coenzyme Q10 2 mg, and asthaxantin 0.5 mg. RESULTS: The lipid profile was significantly improved by AP vs. diet: 1.8% decrease in total cholesterol on diet and a further 15.3% decrease with AP vs. diet (P<0.001); a 3.1% decrease in LDL cholesterol after diet and an 18.9% decrease after AP treatment vs diet alone (P<0.01); a 2.3% decrease in triglycerides after diet alone and a 36.5% decrease after AP vs. diet (P<0.05). CONCLUSION: Adequate life style therapy is effective in reducing, but not in normalizing, the lipid profile in patients on hormone-therapy following breast cancer. The use of natural nutraceuticals as AP, combined with diet, leads to a good therapeutic response and optimal acceptance by the patients.


Assuntos
Berberina/uso terapêutico , Produtos Biológicos/uso terapêutico , Suplementos Nutricionais , Hiperlipidemias/dietoterapia , Hiperlipidemias/prevenção & controle , Antineoplásicos Hormonais/efeitos adversos , Inibidores da Aromatase/uso terapêutico , Neoplasias da Mama/terapia , Feminino , Humanos , Hiperlipidemias/induzido quimicamente , Pessoa de Meia-Idade , Projetos Piloto , Tamoxifeno/efeitos adversos
9.
Astrobiology ; 12(9): 809-17, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22917035

RESUMO

The discovery of large (>100 u) molecules in Titan's upper atmosphere has heightened astrobiological interest in this unique satellite. In particular, complex organic aerosols produced in atmospheres containing C, N, O, and H, like that of Titan, could be a source of prebiotic molecules. In this work, aerosols produced in a Titan atmosphere simulation experiment with enhanced CO (N(2)/CH(4)/CO gas mixtures of 96.2%/2.0%/1.8% and 93.2%/5.0%/1.8%) were found to contain 18 molecules with molecular formulae that correspond to biological amino acids and nucleotide bases. Very high-resolution mass spectrometry of isotopically labeled samples confirmed that C(4)H(5)N(3)O, C(4)H(4)N(2)O(2), C(5)H(6)N(2)O(2), C(5)H(5)N(5), and C(6)H(9)N(3)O(2) are produced by chemistry in the simulation chamber. Gas chromatography-mass spectrometry (GC-MS) analyses of the non-isotopic samples confirmed the presence of cytosine (C(4)H(5)N(3)O), uracil (C(5)H(4)N(2)O(2)), thymine (C(5)H(6)N(2)O(2)), guanine (C(5)H(5)N(5)O), glycine (C(2)H(5)NO(2)), and alanine (C(3)H(7)NO(2)). Adenine (C(5)H(5)N(5)) was detected by GC-MS in isotopically labeled samples. The remaining prebiotic molecules were detected in unlabeled samples only and may have been affected by contamination in the chamber. These results demonstrate that prebiotic molecules can be formed by the high-energy chemistry similar to that which occurs in planetary upper atmospheres and therefore identifies a new source of prebiotic material, potentially increasing the range of planets where life could begin.


Assuntos
Aminoácidos/química , Nucleotídeos/química , Saturno , Atmosfera/análise , Meio Ambiente Extraterreno , Cromatografia Gasosa-Espectrometria de Massas , Gases/análise
10.
G Ital Med Lav Ergon ; 32(4 Suppl): 90-1, 2010.
Artigo em Italiano | MEDLINE | ID: mdl-21438226

RESUMO

Health promotion and education to the future and sustainability are a new potential approach in order to try to reduce diet- and lifestyle-related diseases (cancer, metabolic disorders, obesity, neurodegenerative diseases). Inclusion of educational pathways associated to food consumption out of the home, especially in the workplace, may represent a brand new strategy of intervention, an alternative to the disappointing results of more traditional information-educational strategies implemented so far.


Assuntos
Dieta , Alimentos , Educação em Saúde , Promoção da Saúde/métodos , Saúde Ocupacional , Previsões , Promoção da Saúde/tendências , Humanos , Local de Trabalho
11.
J Phys Chem A ; 113(42): 11195-203, 2009 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-19827851

RESUMO

In this work Titan's atmospheric chemistry is simulated using a capacitively coupled plasma radio frequency discharge in a N(2)-CH(4) stationnary flux. Samples of Titan's tholins are produced in gaseous mixtures containing either 2 or 10% methane before the plasma discharge, covering the methane concentration range measured in Titan's atmosphere. We study their solubility and associated morphology, their infrared spectroscopy signature and the mass distribution of the soluble fraction by mass spectrometry. An important result is to highlight that the previous Titan's tholin solubility studies are inappropriate to fully characterize such a heterogeneous organic matter and we develop a new protocol to evaluate quantitatively tholins solubility. We find that tholins contain up to 35% in mass of molecules soluble in methanol, attached to a hardly insoluble fraction. Methanol is then chosen as a discriminating solvent to characterize the differences between soluble and insoluble species constituting the bulk tholins. No significant morphological change of shape or surface feature is derived from scanning electron microscopy after the extraction of the soluble fraction. This observation suggests a solid structure despite an important porosity of the grains. Infrared spectroscopy is recorded for both fractions. The IR spectra of the bulk, soluble, and insoluble tholins fractions are found to be very similar and reveal identical chemical signatures of nitrogen bearing functions and aliphatic groups. This result confirms that the chemical information collected when analyzing only the soluble fraction provides a valuable insight representative of the bulk material. The soluble fraction is ionized with an atmospheric pressure photoionization source and analyzed by a hybrid mass spectrometer. The congested mass spectra with one peak at every mass unit between 50 and 800 u confirm that the soluble fraction contains a complex mixture of organic molecules. The broad distribution, however, exhibits a regular pattern of mass clusters. Tandem collision induced dissociation analysis is performed in the negative ion mode to retrieve structural information. It reveals that (i) the molecules are ended by methyl, amine and cyanide groups, (ii) a 27 u neutral moiety (most probably HCN) is often released in the fragmentation of tholin anions, and (iii) an ubiquitous ionic fragment at m/z 66 is found in all tandem spectra. A tentative structure is proposed for this negative ion.


Assuntos
Atmosfera/química , Meio Ambiente Extraterreno/química , Saturno , Pressão Atmosférica , Espectrometria de Massas , Metano/química , Metanol/química , Microscopia Eletrônica de Varredura , Estrutura Molecular , Nitrogênio/química , Tamanho da Partícula , Porosidade , Solubilidade , Solventes/química , Espectrofotometria Infravermelho
12.
J Hazard Mater ; 166(2-3): 788-95, 2009 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-19135792

RESUMO

Removal of oxyanions (selenite, selenate, arsenate, phosphate and nitrate) during calcite formation was experimentally studied using aqueous carbonation of calcium hydroxide under moderate pressure (P(CO2) congruent with 20 bar) and temperature (30 degrees C). The effects of Ca(OH)(2) dose (10 and 20 g), Ca(OH)(2) source (commercial pure material or alkaline paper mill waste) and oxyanion initial concentration (from 0 to 70 mg atom/L) were investigated for this anisobaric gas-liquid-solid system. The Ca(OH)(2) carbonation reaction allowed successfully the removal of selenite (>90%), arsenate (>78%) and phosphate (congruent with 100%) from synthetic solutions. Conversely, nitrate and selenate had not any physicochemical affinity/effect during calcite formation. The rate of CO(2) transfer during calcite formation in presence of oxyanions was equal or slower than for an oxyanion-free system, allowing to define a retarding kinetic factor RF that can vary between 0 (no retarding effect) to 1 (total inhibition). For selenite and phosphate RF was quite high, close to 0.3. A small retarding effect was detected for arsenate (RF approximately 0.05) and no retarding effect was detected for selenate and nitrate (RF approximately 0). In general, RF depends on the oxyanion initial concentration, oxyanion nature and Ca(OH)(2) dose. The presence of oxyanions could also influence the crystal morphology and aggregation/agglomeration process. For example, a c-axis elongation of calcite crystals was clearly observed at the equilibrium, for calcite formation in presence of selenite and phosphate. The oxyanions removal process proposed herein was inspired on the common physicochemical treatment of wastewater using calcium hydroxide (Ca(OH)(2)). The particularity, for this novel method is the simultaneous calcium hydroxide carbonation with compressed carbon dioxide in order to stabilise the solid matter. This economical and ecological method could allow the removal of various oxyanions as well as the ex situ mineral sequestration of CO(2); particularly, when the Ca(OH)(2) source comes from alkaline solid waste.


Assuntos
Ânions/isolamento & purificação , Hidróxido de Cálcio/química , Dióxido de Carbono/química , Resíduos Industriais/prevenção & controle , Poluentes Químicos da Água/isolamento & purificação , Arseniatos/isolamento & purificação , Fosfatos/isolamento & purificação , Selenito de Sódio/isolamento & purificação , Purificação da Água/métodos
13.
J Altern Complement Med ; 6(3): 281-7, 2000 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-10890339

RESUMO

OBJECTIVES: To describe in detail the questions and deliberations leading to the development of a methodologically rigorous protocol to test the effectiveness of acupuncture on painful shoulder. DESIGN: Randomized controlled trial using three groups, including one control group. SETTINGS/LOCATION: A hospital in the north of Italy treating at least 8-10 painful shoulders a day, with physician/acupuncturists, physiotherapists, and assessors available to participate in the study. SUBJECTS: Sixty patients with monolateral painful shoulder. A list of exclusion criteria is given. INTERVENTIONS: Acupuncture + mobilization; mobilization alone (control); ear acupuncture + mobilization. OUTCOME MEASURES: Severity of pain, scored on a visual analogue scale (VAS) and on the McGill Pain Questionnaire and restriction of range of motion (ROM) of the shoulder joint. Voluntary use of pain medication, Tenoxicam 20 mg, was added to the protocol. RESULTS: The research team developed a protocol and methodology that avoids the common flaws and difficulties of previous clinical trials on acupuncture. CONCLUSIONS: Physicians and acupuncture specialists will benefit from the advice and support of a project group consisting of experienced clinicians, researchers, and statisticians when designing and preparing clinical trials on acupuncture and other complementary and alternative therapies.


Assuntos
Terapia por Acupuntura , Manejo da Dor , Articulação do Ombro , Protocolos Clínicos , Humanos , Cooperação Internacional , Itália , Modalidades de Fisioterapia , Índice de Gravidade de Doença , Inquéritos e Questionários , Resultado do Tratamento
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