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1.
Int J Mol Sci ; 23(8)2022 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-35457069

RESUMO

Glycine (Gly), NH2CH2COOH, is the simplest amino acid. Although it has not been directly detected in the interstellar gas-phase medium, it has been identified in comets and meteorites, and its synthesis in these environments has been simulated in terrestrial laboratory experiments. Likewise, condensation of Gly to form peptides in scenarios resembling those present in a primordial Earth has been demonstrated experimentally. Thus, Gly is a paradigmatic system for biomolecular building blocks to investigate how they can be synthesized in astrophysical environments, transported and delivered by fragments of asteroids (meteorites, once they land on Earth) and comets (interplanetary dust particles that land on Earth) to the primitive Earth, and there react to form biopolymers as a step towards the emergence of life. Quantum chemical investigations addressing these Gly-related events have been performed, providing fundamental atomic-scale information and quantitative energetic data. However, they are spread in the literature and difficult to harmonize in a consistent way due to different computational chemistry methodologies and model systems. This review aims to collect the work done so far to characterize, at a quantum mechanical level, the chemical life of Gly, i.e., from its synthesis in the interstellar medium up to its polymerization on Earth.


Assuntos
Meio Ambiente Extraterreno , Meteoroides , Poeira Cósmica/análise , Planeta Terra , Evolução Química , Glicina
2.
J. investig. allergol. clin. immunol ; 32(1): 33-39, 2022. graf, tab
Artigo em Inglês | IBECS | ID: ibc-ADZ-318

RESUMO

Objective: To analyze component-resolved diagnosis of sensitization to Dermatophagoides pteronyssinus (Der p) in patients with respiratory allergy and the association between diagnostic findings and clinical severity in different geographical areas.Methods: The study population comprised 217 patients (mean age, 25.85 [12.7] years; 51.16% female) selected from 13 centers in Portugal (5 from the North, n=65). All had allergic rhinitis with or without asthma and positive skin prick test results to at least 1 dust mite. Specific IgE (sIgE) to Der p, Dermatophagoides farinae, Lepidoglyphus destructor, Der p 1, Der p 2, Der p 10, and Der p 23 was determined using ImmunoCAP. The Mann-Whitney test was applied for the following comparisons: rhinitis vs rhinitis and asthma; mild vs moderate-to-severe rhinitis; North vs South.Results: The prevalence of sensitization was 98.2% for Der p, and 72.4%, 89.4%, 9.7%, and 77% for Der p 1, Der p 2, Der p 10, and Der p 23, respectively. The corresponding median sIgE levels were 8.56, 17.7, 0.01, and 3.95 kUA/L. sIgE to all allergens was higher in patients with moderate-to-severe rhinitis and rhinitis with asthma (nonsignficant). Concentrations of sIgE to Der p 2 were significantly higher in the South than in the North (P=.0496).Conclusions: The most common sensitization in Portugal was to Der p. The highest prevalence and median sIgE level were observed for Der p 2. All sIgE values for molecular components were higher in more symptomatic patients (nonsignificant). Concentrations of sIgE to Der p 2 were higher in the South, probably because of the warmer temperature and/or the larger sample size (AU)


Objetivo: Analizar el diagnóstico por componentes para Dermatophagoides pteronyssinus (Der p) en pacientes con alergia respiratoria ysu relación con la gravedad clínica en diferentes áreas geográficas.Métodos: Se incluyeron 217 pacientes (edad media 25,85±12,7 años; 51,16% mujeres), seleccionados de 13 centros en Portugal (5 delNorte, n = 65). Todos tenían rinitis alérgica, con o sin asma, y tenían pruebas positivas en prick a al menos un ácaro del polvo. La IgEespecífica (sIgE) para Der p, Dermatophagoides farinae, Lepidoglyphus destructor, Der p 1, Der p 2, Der p 10 y Der p 23 se determinaronpor ImmunoCAP. El análisis estadístico (prueba U de Mann Whitney) comparó pacientes con rinitis frente a rinitis y asma; rinitis leve frentea moderada-grave; Norte frente a Sur.Resultados: La prevalencia de sensibilización fue del 98,2% para Der p, y del 72,4%, 89,4%, 9,7% y 77% para Der p 1, Der p 2, Der p 10y Der p 23, respectivamente. Las medianas de sIgE fueron de 8,56, 17,7, 0,01 y 3,95 kUA/ L. Las medianas de sIgE de todos los alérgenosfue mayor en pacientes con rinitis de moderada a grave y rinitis con asma, pero no estadísticamente significativo (NSS). El valor de Der p2 fue significativamente mayor en el Sur en comparación con el Norte (p = 0,0496).Conclusiones: La sensibilización a Der p es la más común en Portugal. Der p 2 tuvo la prevalencia más alta y los niveles medios más altos.Todos los componentes moleculares fueron mayores en pacientes más sintomáticos (NSS). El valor de Der p 2 fue mayor en el Sur, lo quepuede estar relacionado con la temperatura más cálida y/o el tamaño de muestra más grande (AU)


Assuntos
Humanos , Masculino , Feminino , Pré-Escolar , Criança , Adolescente , Adulto Jovem , Adulto , Pessoa de Meia-Idade , Rinite Alérgica/diagnóstico , Rinite Alérgica/etiologia , Dermatophagoides pteronyssinus/imunologia , Índice de Gravidade de Doença , Rinite Alérgica/epidemiologia , Geografia , Portugal/epidemiologia , Testes Cutâneos , Poeira Cósmica , Fatores de Risco
3.
Astrobiology ; 21(12): 1479-1493, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34793260

RESUMO

Amino acids have been detected in extraterrestrial bodies such as carbonaceous chondrites (CCs), which suggests that extraterrestrial organics could be the source of the first life on Earth, and interplanetary dust particles (IDPs) or micrometeorites (MMs) are promising carriers of extraterrestrial organic carbon. Some amino acids found in CCs are amino acid precursors, but these have not been well characterized. The Tanpopo mission was conducted in Earth orbit from 2015 to 2019, and the stability of glycine (Gly), hydantoin (Hyd), isovaline (Ival), 5-ethyl-5-methylhydantoin (EMHyd), and complex organics formed by proton irradiation from CO, NH3, and H2O (CAW) in space were analyzed by high-performance liquid chromatography and/or gas chromatography/mass spectrometry. The target substances showed a logarithmic decomposition over 1-3 years upon space exposure. Recoveries of Gly and CAW were higher than those of Hyd, Ival, and EMHyd. Ground simulation experiments showed different results: Hyd was more stable than Gly. Solar ultraviolet light was fatal to all organics, and they required protection when carried by IDPs/MMs. Thus, complex amino acid precursors (such as CAW) were possibly more robust than simple precursors during transportation to primitive Earth. The Tanpopo 2 mission is currently being conducted to expose organics to more probable space conditions.


Assuntos
Meteoroides , Voo Espacial , Aminoácidos/análise , Poeira Cósmica/análise , Planeta Terra , Meio Ambiente Extraterreno
4.
Astrobiology ; 21(12): 1451-1460, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34449275

RESUMO

The Tanpopo experiment was the first Japanese astrobiology mission on board the Japanese Experiment Module Exposed Facility on the International Space Station (ISS). The experiments were designed to address two important astrobiological topics, panspermia and the chemical evolution process toward the generation of life. These experiments also tested low-density aerogel and monitored the microdebris environment around low Earth orbit. The following six subthemes were identified to address these goals: (1) Capture of microbes in space: Estimation of the upper limit of microbe density in low Earth orbit; (2) Exposure of microbes in space: Estimation of the survival time course of microbes in the space environment; (3) Capture of cosmic dust on the ISS and analysis of organics: Detection of the possible presence of organic compounds in cosmic dust; (4) Alteration of organic compounds in space environments: Evaluation of decomposition time courses of organic compounds in space; (5) Space verification of the Tanpopo hyper-low-density aerogel: Durability and particle-capturing capability of aerogel; (6) Monitoring of the number of space debris: Time-dependent change in space debris environment. Subthemes 1 and 2 address the panspermia hypothesis, whereas 3 and 4 address the chemical evolution. The last two subthemes contribute to space technology development. Some of the results have been published previously or are included in this issue. This article summarizes the current status of the Tanpopo experiments.


Assuntos
Exobiologia , Voo Espacial , Poeira Cósmica/análise , Planeta Terra , Meio Ambiente Extraterreno , Japão , Compostos Orgânicos/análise , Astronave
5.
Phys Life Rev ; 37: 65-93, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33774429

RESUMO

An interdisciplinary review of the chemical literature that points to a unifying scenario for the origin of life, referred to as the Primordial Multifunctional organic Entity (PriME) scenario, is provided herein. In the PriME scenario it is suggested that the Insoluble Organic Matter (IOM) in carbonaceous chondrites, as well as interplanetary dust particles from meteorites and comets may have played an important role in the three most critical processes involved in the origin of life, namely 1) metabolism, via a) the provision and accumulation of molecules that are the building blocks of life, b) catalysis (e.g., by templation), and c) protection of developing life molecules against radiation by excited state deactivation; 2) compartmentalization, via adsorption of compounds on the exposed organic surfaces in fractured meteorites, and 3) replication, via deaggregation, desorption and related physical phenomena. This scenario is based on the hitherto overlooked structural and physicochemical similarities between the IOM and the dark, insoluble, multifunctional melanin polymers found in bacteria and fungi and associated with the ability of these microorganisms to survive extreme conditions, including ionizing radiation. The underlying conceptual link between these two materials is strengthened by the fact that primary precursors of bacterial and fungal melanins (collectively referred to herein as allomelanins) are hydroxylated aromatic compounds like homogentisic acid and 1,8-dihydroxynaphthalene, and that similar hydroxylated aromatic compounds, including hydroxynaphthalenes, figure prominently among possible components of the organic materials on dust grains and ices in the interstellar matter, and may be involved in the formation of IOM in meteorites. Inspired by this rationale, a vis-à-vis review of the properties of IOM from various chondrites and non-nitrogenous allomelanin pigments from bacteria and fungi is provided herein. The unrecognized similarities between these materials may pave the way for a novel scenario at the origin of life, in which IOM-related complex organic polymers delivered to the early Earth are proposed to serve as PriME and were preserved and transformed in those primitive forms of life that shared the ability to synthesize melanin polymers playing an important role in the critical processes underlying the establishment of terrestrial eukaryotes.


Assuntos
Meteoroides , Poeira Cósmica/análise , Planeta Terra , Melaninas , Compostos Orgânicos/análise , Origem da Vida
6.
Adv Genet ; 106: 109-117, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33081920

RESUMO

Exchanges of information analogous to a global internet have been known to take place between biological systems on the Earth ranging from bacteria and viruses to plants and animals. We argue that this process can be extended to include a cosmic biosphere within which evolution would seem to be intimately interlinked across astronomical, perhaps cosmological distance scales. Comets and interstellar dust, argued to have a bacterial/viral component, could be involved in establishing these links.


Assuntos
Bactérias/genética , Vírus/genética , Animais , Poeira Cósmica , Humanos , Internet , Plantas/genética
7.
Adv Genet ; 106: 5-20, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33081926

RESUMO

A range of astronomical observations are shown to be in accord with the theory of cometary panspermia. This theory posits that comets harbor a viable biological component in the form of bacteria and viruses that led to origin and evolution of life on Earth. The data includes (1) infrared, visual and ultraviolet spectra of interstellar dust, (2) infrared spectra of the dust released from comet Halley in 1986, (3) infrared spectra of comet Hale-Bopp in 1997, (4) near and mid-infrared spectra of comet Tempel I in 2005, (5) the discovery of an amino acid and degradation products attributable to biology in the material recovered from the Stardust Mission in 2009, (6) jets from comet Lovejoy showing both a sugar and Ethyl alcohol and finally, (7) a diverse set of data that has emerged from the Rosetta mission. The conjunction of all the available data points to cometary biology and interstellar panspermia as being inevitable.


Assuntos
Poeira Cósmica , Origem da Vida , Aminoácidos , Animais , Bactérias , Humanos , Vírus
8.
Astrobiology ; 20(2): 179-189, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31825243

RESUMO

Reliable identification of biosignatures, such as amino acids, fatty acids, and peptides, on extraterrestrial ocean worlds is a key prerequisite for space missions that search for life or its emergence on these worlds. One promising approach is the use of high-performance in situ impact ionization mass spectrometers to sample water ice grains emerging from ocean-bearing moons such as Europa or Enceladus. A predecessor of such detectors, the Cosmic Dust Analyzer on board the Cassini spacecraft, has proven to be very successful in analyzing inorganic and organic ocean constituents and with that characterizing the habitability of Enceladus ocean. However, biosignatures have not been definitively identified in extraterrestrial ocean environments so far. Here, we investigate with an analog experiment the spectral appearance of amino acids, fatty acids, and peptides in water ice grains, together with their detection limits, as applicable to spaceborne mass spectrometers. We employ a laboratory-based laser induced liquid beam ion desorption technique, proven to simulate accurately the impact ionization mass spectra of water ice grains over a wide range of impact speeds. The investigated organics produce characteristic mass spectra, with molecular peaks as well as clearly identifiable, distinctive fragments. We find the detection limits of these key biosignatures to be at the µM or nM level, depending on the molecular species and instrument polarity, and infer that impact ionization mass spectrometers are most sensitive to the molecular peaks of these biosignatures at encounter velocities of 4-6 km/s.


Assuntos
Biomarcadores/análise , Exobiologia/métodos , Meio Ambiente Extraterreno/química , Gelo/análise , Espectrometria de Massas/métodos , Aminoácidos/análise , Poeira Cósmica/análise , Ácidos Graxos/análise , Limite de Detecção , Oceanos e Mares , Peptídeos/análise , Saturno
9.
J Appl Toxicol ; 39(10): 1413-1423, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31319435

RESUMO

Lunar regolith samples collected during previous Apollo missions were found to contain components that were established to be toxic to humans; however, the health effects due to inhalation of lunar soil as a whole are still unknown. Macrophages residing in the alveolar sacs of the lungs constitute one of the last lines of defense against inhaled particulates before entry into the bloodstream. Here, we examine the macrophage response to lunar simulants that are similar in chemical composition to the lunar regolith. We assess cytotoxicity, cellular morphology, phagocytosis of simulants and expression of inflammatory markers. Overall, the exposure of macrophages to lunar simulants results in moderate cytotoxicity and marked alteration of cell morphology and uptake of the simulants. Interestingly, simulant exposure decreased proinflammatory gene expression, but may induce an anti-inflammatory phenotype in the cells. These results illustrate that although macrophages phagocytose lunar simulants as a protective response, the simulants do induce a degree of macrophage cell death. Our study reveals some toxicity associated with lunar simulants and supports further evaluation of the inhalation of lunar regolith to understand the risks of exposure fully.


Assuntos
Sobrevivência Celular/efeitos dos fármacos , Poeira Cósmica/efeitos adversos , Macrófagos/efeitos dos fármacos , Lua , Solo/química , Voo Espacial , Administração por Inalação , Humanos
10.
Aerosp Med Hum Perform ; 90(8): 709-719, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31331421

RESUMO

INTRODUCTION: Exposure to excess manganese (Mn) can cause multiple toxicological outcomes in humans, most notably neurotoxicity. Ample epidemiological evidence suggests that chronic, low-level exposure causes subclinical cognitive effects. Because NASA astronauts will be exposed to Mars regolith, Spacecraft Maximum Allowable Concentrations (SMACs) were developed following an extensive literature review.METHODS: Multiple databases were searched for information relevant to derivation of Mn SMAC values. An additional search for Mars dust data was performed. Risk assessment approaches were applied, including adjustments for space-relevant susceptibility to Mn effects, to develop limits for 1-h to 1000-d exposures. Rover data informed the assessment and enabled calculation of allowable total dust exposure based on Mn content.RESULTS: Over 400 relevant sources were identified. Applicability of exposure characteristics and data collection methods influenced key study choice. SMACs ranging from 3 mg · m-3 (1 h) - 0.0079 mg · m-3 (1000 d) were set to protect primarily against neurocognitive and respiratory effects. Considering 0.38 wt% total Mn presence in the dust, maximum recommended total dust exposure should not exceed 790 mg · m-3 (1 h) - 2 mg · m-3 (1000 d).DISCUSSION: This literature review allowed for identification of relevant studies to inform SMAC development. Manganese is one of several components to consider when developing an appropriate total dust limit for Martian dust; other dust elements may alter Mn bioavailability. Mission-specific activities may require alteration of assumptions regarding Mn dust concentration and exposure duration. However, based on expected toxicity of particulate matter itself, the acute SMACs are protective, even with transient exposure during activities that could produce higher concentrations.Romoser AA, Ryder VE, McCoy JT. Spacecraft maximum allowable concentrations for manganese compounds in Mars dust. Aerosp Med Hum Perform. 2019; 90(8):709-719.


Assuntos
Poluentes Ocupacionais do Ar/efeitos adversos , Poeira Cósmica , Compostos de Manganês , Exposição Ocupacional/efeitos adversos , Astronave , Humanos , Marte , Concentração Máxima Permitida , Medição de Risco
11.
Orig Life Evol Biosph ; 49(1-2): 89-103, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31218479

RESUMO

The Structure of carbodiimide has been studied by using quantum chemical methods. Carbodiimide (HNCNH) has been detected towards Sagittarius B2 (N) in interstellar medium (ISM). Two reaction mechanisms have been proposed to study the formation of interstellar Carbodiimide. The first reaction mechanism is based on molecule-radical and the second one is a radical-radical mechanism, through previously detected interstellar molecules or radicals. Quantum chemical calculations have been performed by using density functional theory (DFT) and Moller-Plesset second order perturbation (MP2) theory, in gas phase as well as in polarizable continuum model (PCM). The proposed reaction paths are exothermic and barrierless which indicates the possibility of carbodiimide formation in ISM. Several basis sets have been used to verify the validity and accuracy of the results. The isotropic and anisotropic polarizabilities of carbodiimide have been calculated from relevant tensor components for both reaction mechanisms with the help of data obtained by DFT/B3LYP and MP2 methods using aug-cc-pVTZ basis sets in gaseous phase as well as in PCM.


Assuntos
Carbodi-Imidas/química , Gases/química , Teoria Quântica , Poeira Cósmica , Modelos Químicos , Modelos Moleculares
12.
Environ Toxicol ; 34(2): 131-140, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30496634

RESUMO

Lunar dust is one of the biggest risk factors in the future manned exploration mission. Much is not known about the pulmonary toxicity of lunar dust. The aim of this study was to evaluate the lung inflammation and oxidative stress induced by subacute exposure to lunar dust stimulant (LDS) in rats. Wistar rats were intratracheally administered LDS, twice a week for 3 weeks. Inflammatory cell counting and cytokine assays using bronchoalveolar lavage fluid (BALF) were performed. Lung tissues were processed for histopathological examination and immunohistochemical staining. Biomarkers of oxidative stress and genes and proteins related to inflammation and fibrosis in lung tissue were also determined. The neutrophil count in the BALF of LDS-exposed groups was higher than that in controls (P < .05). LDS caused a significant increase in some of biochemical indicators and proinflammatory factors levels in BALF compared with control group. The normal balance between oxidation and antioxidation was broken by LDS. Pathological characteristics of lung tissue and immunohistochemical results for α-smooth muscle actin (α-SMA) indicated that inflammatory response was an extremely important passage to pulmonary fibrosis. Real-time PCR analysis showed elevated levels of nitric oxide synthase (NOS) and nicotinamide adenine dinucleotide phosphate oxidase (NOX) mRNA in the lungs (P < .05). Western blotting results were consistent with immunohistochemistry and qPCR results. These results indicate that inhalation of lunar dust may cause inflammatory pulmonary fibrosis. NOX4 may be a key potential therapeutic target for inflammatory injury and fibrosis in the lung.


Assuntos
Poluentes Atmosféricos/toxicidade , Poeira Cósmica/efeitos adversos , Poeira/análise , Pulmão/efeitos dos fármacos , Pneumonia/induzido quimicamente , Fibrose Pulmonar/induzido quimicamente , Poluentes Atmosféricos/química , Animais , Líquido da Lavagem Broncoalveolar/citologia , Líquido da Lavagem Broncoalveolar/imunologia , Contagem de Células , Citocinas/imunologia , Exposição por Inalação , Pulmão/metabolismo , Pulmão/patologia , Masculino , Tamanho da Partícula , Pneumonia/metabolismo , Pneumonia/patologia , Fibrose Pulmonar/metabolismo , Fibrose Pulmonar/patologia , Ratos , Ratos Wistar
13.
ScientificWorldJournal ; 2018: 7360147, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29849510

RESUMO

Cosmic dust samples from the surface of the illuminator of the International Space Station (ISS) were collected by a crew member during his spacewalk. The sampler with tampon in a vacuum container was delivered to the Earth. Washouts from the tampon's material and the tampon itself were analyzed for the presence of bacterial DNA by the method of nested PCR with primers specific to DNA of the genus Mycobacteria, DNA of the strains of capsular bacteria Bacillus, and DNA encoding 16S ribosomal RNA. The results of amplification followed by sequencing and phylogenetic analysis indicated the presence of the bacteria of the genus Mycobacteria and the extreme bacterium of the genus Delftia in the samples of cosmic dust. It was shown that the DNA sequence of one of the bacteria of the genus Mycobacteria was genetically similar to that previously observed in superficial micro layer at the Barents and Kara seas' coastal zones. The presence of the wild land and marine bacteria DNA on the ISS suggests their possible transfer from the stratosphere into the ionosphere with the ascending branch of the global electric circuit. Alternatively, the wild land and marine bacteria as well as the ISS bacteria may all have an ultimate space origin.


Assuntos
Poeira Cósmica/análise , DNA Bacteriano/genética , Planeta Terra , Oceanos e Mares , Astronave , Sequência de Bases , Genes Bacterianos , Filogenia , RNA Ribossômico 16S/genética
14.
Proc Natl Acad Sci U S A ; 114(43): 11327-11332, 2017 10 24.
Artigo em Inglês | MEDLINE | ID: mdl-28973920

RESUMO

Before the origin of simple cellular life, the building blocks of RNA (nucleotides) had to form and polymerize in favorable environments on early Earth. At this time, meteorites and interplanetary dust particles delivered organics such as nucleobases (the characteristic molecules of nucleotides) to warm little ponds whose wet-dry cycles promoted rapid polymerization. We build a comprehensive numerical model for the evolution of nucleobases in warm little ponds leading to the emergence of the first nucleotides and RNA. We couple Earth's early evolution with complex prebiotic chemistry in these environments. We find that RNA polymers must have emerged very quickly after the deposition of meteorites (less than a few years). Their constituent nucleobases were primarily meteoritic in origin and not from interplanetary dust particles. Ponds appeared as continents rose out of the early global ocean, but this increasing availability of "targets" for meteorites was offset by declining meteorite bombardment rates. Moreover, the rapid losses of nucleobases to pond seepage during wet periods, and to UV photodissociation during dry periods, mean that the synthesis of nucleotides and their polymerization into RNA occurred in just one to a few wet-dry cycles. Under these conditions, RNA polymers likely appeared before 4.17 billion years ago.


Assuntos
Fontes Hidrotermais , Modelos Teóricos , Nucleotídeos/química , RNA/química , Adenina/química , Poeira Cósmica , Planeta Terra , Evolução Molecular , Meteoroides , Origem da Vida , Polimerização , Uracila/química
15.
Astrobiology ; 16(12): 997-1012, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-28001448

RESUMO

The chemical history of carbon is traced from its origin in stellar nucleosynthesis to its delivery to planet surfaces. The molecular carriers of this element are examined at each stage in the cycling of interstellar organic material and their eventual incorporation into solar system bodies. The connection between the various interstellar carbon reservoirs is also examined. Carbon has two stellar sources: supernova explosions and mass loss from evolved stars. In the latter case, the carbon is dredged up from the interior and then ejected into a circumstellar envelope, where a rich and unusual C-based chemistry occurs. This molecular material is eventually released into the general interstellar medium through planetary nebulae. It is first incorporated into diffuse clouds, where carbon is found in polyatomic molecules such as H2CO, HCN, HNC, c-C3H2, and even C60+. These objects then collapse into dense clouds, the sites of star and planet formation. Such clouds foster an active organic chemistry, producing compounds with a wide range of functional groups with both gas-phase and surface mechanisms. As stars and planets form, the chemical composition is altered by increasing stellar radiation, as well as possibly by reactions in the presolar nebula. Some molecular, carbon-rich material remains pristine, however, encapsulated in comets, meteorites, and interplanetary dust particles, and is delivered to planet surfaces. Key Words: Carbon isotopes-Prebiotic evolution-Interstellar molecules-Comets-Meteorites. Astrobiology 16, 997-1012.


Assuntos
Carbono/análise , Planetas , Astros Celestes/química , Poeira Cósmica/análise , Meteoroides
16.
Orig Life Evol Biosph ; 45(1-2): 225-9, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25794831

RESUMO

In this paper, we report the progress in developing a silica-aerogel-based cosmic dust capture panel for use in the Tanpopo experiment on the International Space Station (ISS). Previous studies revealed that ultralow-density silica aerogel tiles, comprising two layers with densities of 0.01 and 0.03 g/cm(3) developed using our production technique, were suitable for achieving the scientific objectives of the astrobiological mission. A special density configuration (i.e., box framing) aerogel with a holder was designed to construct the capture panels. Qualification tests for an engineering model of the capture panel as an instrument aboard the ISS were successful. Sixty box-framing aerogel tiles were manufactured in a contamination-controlled environment.


Assuntos
Poeira Cósmica/análise , Exobiologia/métodos , Sílica Gel/química , Astronave
17.
Orig Life Evol Biosph ; 45(1-2): 113-21, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25720971

RESUMO

Recent research has discovered that complex organic matter is prevalent throughout the Universe. In the Solar System, it is found in meteorites, comets, interplanetary dust particles, and planetary satellites. Spectroscopic signatures of organics with aromatic/aliphatic structures are also found in stellar ejecta, diffuse interstellar medium, and external galaxies. From space infrared spectroscopic observations, we have found that complex organics can be synthesized in the late stages of stellar evolution. Shortly after the nuclear synthesis of the element carbon, organic gas-phase molecules are formed in the stellar winds, which later condense into solid organic particles. This organic synthesis occurs over very short time scales of about a thousand years. In order to determine the chemical structures of these stellar organics, comparisons are made with particles produced in the laboratory. Using the technique of chemical vapor deposition, artificial organic particles have been created by injecting energy into gas-phase hydrocarbon molecules. These comparisons led us to believe that the stellar organics are best described as amorphous carbonaceous nanoparticles with mixed aromatic and aliphatic components. The chemical structures of the stellar organics show strong similarity to the insoluble organic matter found in meteorites. Isotopic analysis of meteorites and interplanetary dust collected in the upper atmospheres have revealed the presence of pre-solar grains similar to those formed in old stars. This provides a direct link between star dust and the Solar System and raises the possibility that the early Solar System was chemically enriched by stellar ejecta with the potential of influencing the origin of life on Earth.


Assuntos
Galáxias , Compostos Orgânicos/análise , Sistema Solar , Astros Celestes , Poeira Cósmica , Meteoroides
18.
Orig Life Evol Biosph ; 44(3): 169-74, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25515345

RESUMO

The influence of complex dust composition on the general chemical evolution of a prestellar core and the content of complex organic compounds is studied. It is shown that various component groups respond differently to the presence of a small dust population. At early stages the difference is determined primarily by changes in the balance of photo processes due to effective absorption of ultraviolet photons by small dust grains of the second population and collisional reactions with dust particles. At later stages differences are also caused by the growing dominance of additional reaction channels related to surface organic synthesis.


Assuntos
Poeira Cósmica/análise , Exobiologia , Compostos Orgânicos/análise , Fótons , Astros Celestes/química , Evolução Química , Processos Fotoquímicos , Raios Ultravioleta
19.
Faraday Discuss ; 168: 249-66, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25302384

RESUMO

In the interstellar medium, UV photolysis of condensed methanol (CH3OH), contained in ice mantles surrounding dust grains, is thought to be the mechanism that drives the formation of "complex" molecules, such as methyl formate (HCOOCH3), dimethyl ether (CH3OCH3), acetic acid (CH3COOH), and glycolaldehyde (HOCH2CHO). The source of this reaction-initiating UV light is assumed to be local because externally sourced UV radiation cannot penetrate the ice-containing dark, dense molecular clouds. Specifically, exceedingly penetrative high-energy cosmic rays generate secondary electrons within the clouds through molecular ionizations. Hydrogen molecules, present within these dense molecular clouds, are excited in collisions with these secondary electrons. It is the UV light, emitted by these electronically excited hydrogen molecules, that is generally thought to photoprocess interstellar icy grain mantles to generate "complex" molecules. In addition to producing UV light, the large numbers of low-energy (< 20 eV) secondary electrons, produced by cosmic rays, can also directly initiate radiolysis reactions in the condensed phase. The goal of our studies is to understand the low-energy, electron-induced processes that occur when high-energy cosmic rays interact with interstellar ices, in which methanol, a precursor of several prebiotic species, is the most abundant organic species. Using post-irradiation temperature-programmed desorption, we have investigated the radiolysis initiated by low-energy (7 eV and 20 eV) electrons in condensed methanol at - 85 K under ultrahigh vacuum (5 x 10(-10) Torr) conditions. We have identified eleven electron-induced methanol radiolysis products, which include many that have been previously identified as being formed by methanol UV photolysis in the interstellar medium. These experimental results suggest that low-energy, electron-induced condensed phase reactions may contribute to the interstellar synthesis of "complex" molecules previously thought to form exclusively via UV photons.


Assuntos
Elétrons , Hidrogênio/química , Metanol/química , Astros Celestes/química , Acetaldeído/análogos & derivados , Acetaldeído/síntese química , Ácido Acético/síntese química , Poeira Cósmica/análise , Radiação Cósmica , Ésteres do Ácido Fórmico/síntese química , Gelo/análise , Éteres Metílicos/síntese química , Fotólise , Temperatura , Raios Ultravioleta
20.
Proc Natl Acad Sci U S A ; 111(43): 15338-43, 2014 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-25288736

RESUMO

Isotopically anomalous carbonaceous grains in extraterrestrial samples represent the most pristine organics that were delivered to the early Earth. Here we report on gentle aberration-corrected scanning transmission electron microscopy investigations of eight (15)N-rich or D-rich organic grains within two carbonaceous Renazzo-type (CR) chondrites and two interplanetary dust particles (IDPs) originating from comets. Organic matter in the IDP samples is less aromatic than that in the CR chondrites, and its functional group chemistry is mainly characterized by C-O bonding and aliphatic C. Organic grains in CR chondrites are associated with carbonates and elemental Ca, which originate either from aqueous fluids or possibly an indigenous organic source. One distinct grain from the CR chondrite NWA 852 exhibits a rim structure only visible in chemical maps. The outer part is nanoglobular in shape, highly aromatic, and enriched in anomalous nitrogen. Functional group chemistry of the inner part is similar to spectra from IDP organic grains and less aromatic with nitrogen below the detection limit. The boundary between these two areas is very sharp. The direct association of both IDP-like organic matter with dominant C-O bonding environments and nanoglobular organics with dominant aromatic and C-N functionality within one unique grain provides for the first time to our knowledge strong evidence for organic synthesis in the early solar system activated by an anomalous nitrogen-containing parent body fluid.


Assuntos
Técnicas de Química Sintética , Poeira Cósmica/análise , Meteoroides , Sistema Solar , Microscopia Eletrônica de Transmissão , Análise Espectral
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