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1.
Materials (Basel) ; 17(19)2024 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-39410294

RESUMO

This study explores the modeling, design, simulation, and testing of a new composite material designed for high-strength and high-temperature resistance in in-space optical mining, examining its properties at both the polymer and atomic/molecular levels. At the polymer level, the investigation includes mechanical and thermal performance analyses using COMSOL Multiphysics 6.1, employing layerwise theory, equivalent single layer (ESL) theory, and a multiple-model approach for mechanical modeling, alongside virtual thermal experiments simulating laser heating. Experimentally, porous Polyaniline (PANI) films are fabricated via electrochemical polymerization, with variations in voltage and deposition time, to study their morphology, optical performance, and electrochemical behavior. At the atomic and molecular levels, this study involves modeling the composite material, composed of Nomex, Kevlar, and Spirooxazine-Doped PANI, and simulating its behavior. The significance of this work lies in developing a novel composite material for in-space optical mining, integrating it into optical mining systems, and introducing innovative thermal management solutions, which contribute to future space exploration by improving resource efficiency and sustainability, while also enhancing the understanding of PANI film properties for in-space applications.

2.
Sensors (Basel) ; 24(11)2024 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-38894448

RESUMO

Minor bodies exhibit considerable variability in shape and surface morphology, posing challenges for spacecraft operations, which are further compounded by highly non-linear dynamics and limited communication windows with Earth. Additionally, uncertainties persist in the shape and surface morphology of minor bodies due to errors in ground-based estimation techniques. The growing need for autonomy underscores the importance of robust image processing and visual-based navigation methods. To address this demand, it is essential to conduct tests on a variety of body shapes and with different surface morphological features. This work introduces the procedural Minor bOdy geNErator Tool (MONET), implemented using an open-source 3D computer graphics software. The starting point of MONET is the three-dimensional mesh of a generic minor body, which is procedurally modified by introducing craters, boulders, and surface roughness, resulting in a photorealistic model. MONET offers the flexibility to generate a diverse range of shapes and surface morphological features, aiding in the recreation of various minor bodies. Users can fine-tune relevant parameters to create the desired conditions based on the specific application requirements. The tool offers the capability to generate two default families of models: rubble-pile, characterized by numerous different-sized boulders, and comet-like, reflecting the typical morphology of comets. MONET serves as a valuable resource for researchers and engineers involved in minor body exploration missions and related projects, providing insights into the adaptability and effectiveness of guidance and navigation techniques across a wide range of morphological scenarios.

3.
Sci Total Environ ; 932: 173000, 2024 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-38719050

RESUMO

Ocean acidification and warming affect marine ecosystems from the molecular scale in organismal physiology to broad alterations of ecosystem functions. However, knowledge of their combined effects on tropical-subtropical intertidal species remains limited. Pushing the environmental range of marine species away from the optimum initiates stress impacting biochemical metabolic characteristics, with consequences on lipid-associated and enzyme biochemistry. This study investigates lipid-associated fatty acids (FAs) and enzyme activities involved in biomineralization of the tropical-subtropical starfish Aquilonastra yairi in response to projected near-future global change. The starfish were acclimatized to two temperature levels (27 °C, 32 °C) crossed with three pCO2 concentrations (455 µatm, 1052 µatm, 2066 µatm). Total lipid (ΣLC) and FAs composition were unaffected by combined elevated temperature and pCO2, but at elevated temperature, there was an increase in ΣLC, SFAs (saturated FAs) and PUFAs (polyunsaturated FAs), and a decrease in MUFAs (monounsaturated FAs). However, temperature was the sole factor to significantly alter SFAs composition. Positive parabolic responses of Ca-ATPase and Mg-ATPase enzyme activities were detected at 27 °C with elevated pCO2, while stable enzyme activities were observed at 32 °C with elevated pCO2. Our results indicate that the lipid-associated biochemistry of A. yairi is resilient and capable of coping with near-future ocean acidification and warming. However, the calcification-related enzymes Ca-ATPase and Mg-ATPase activity appear to be more sensitive to pCO2/pH changes, leading to vulnerability concerning the skeletal structure.


Assuntos
Água do Mar , Estrelas-do-Mar , Animais , Água do Mar/química , Concentração de Íons de Hidrogênio , Estrelas-do-Mar/fisiologia , Aquecimento Global , Dióxido de Carbono , Oceanos e Mares , Mudança Climática , Ácidos Graxos/metabolismo , Metabolismo dos Lipídeos , Acidificação dos Oceanos
4.
Sci Rep ; 14(1): 9946, 2024 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-38688982

RESUMO

This study investigates the mechanisms underlying the varied climate changes witnessed during mass extinctions in the Phanerozoic Eon. Climate shifts during mass extinctions have manifested as either predominant global cooling or predominant warming, yet the causes behind these occurrences remain unclear. We emphasize the significance of sedimentary rock temperature in comprehending these climate shifts. Our research reveals that low-temperature heating of sulfide leads to global cooling through the release of sulfur dioxide (SO2), while intermediate-temperature heating of hydrocarbons and carbonates releases substantial carbon dioxide (CO2), contributing to global warming. High-temperature heating additionally generates SO2 from sulfate, further contributing to global cooling. Different degrees of contact heating of the host rock can lead to different dominant volatile gas emissions, crucially driving either warming or cooling. Moreover, medium to high-temperature shock-heating resulting from asteroid impacts produces soot from hydrocarbons, also contributing to global cooling. Large-scale volcanic activity and asteroid impacts are both events that heat rocks, emitting the same gases and particles, causing climate changes. The findings elucidate the critical role of heating temperature and heating time in understanding major climate changes during mass extinctions.

5.
J Fr Ophtalmol ; 47(4): 104105, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38428321

RESUMO

PURPOSE: To compare the visual outcomes in both eyes of patients who undergo phacoemulsification and trifocal intraocular lens (IOL) implantation and have asteroid hyalosis (AH) or synchysis scintillans (SS) in only one eye. METHODS: A retrospective comparative case series was performed. We evaluated uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), uncorrected intermediate visual acuity (UIVA), uncorrected near visual acuity (UNVA), predictability, safety, efficacy, and satisfaction after implantation of the same model of trifocal IOL in both eyes (PhysIOL FineVision Pod-F and Micro-F and Rayner RayOne Trifocal). RESULTS: A total of 164 eyes of 82 patients (41 females, 50%) met the inclusion criteria. There were no statistically significant differences in sphere, cylinder, spherical equivalent, UDVA, UIVA, or UNVA between the groups. Postoperative CDVA was slightly better in the control group (logMAR 0.03) than in the AH/SS group (logMAR 0.04) (P: 0.014). There were no statistically significant differences in predictability, safety index, or efficacy index between the groups. Overall subjective satisfaction was good (98.2%). CONCLUSIONS: Visual outcomes and satisfaction are good after implantation of trifocal IOLs in eyes with AH or SS. Therefore, trifocal IOLs should not be ruled out in these patients when no other vitreoretinal disorder is present.


Assuntos
Lentes Intraoculares , Doenças Orbitárias , Facoemulsificação , Feminino , Humanos , Facoemulsificação/efeitos adversos , Implante de Lente Intraocular/efeitos adversos , Estudos Retrospectivos , Satisfação do Paciente , Lentes Intraoculares/efeitos adversos , Refração Ocular , Transtornos da Visão , Desenho de Prótese , Pseudofacia/complicações , Pseudofacia/cirurgia
6.
Viruses ; 16(3)2024 02 23.
Artigo em Inglês | MEDLINE | ID: mdl-38543709

RESUMO

This study focused on the viruses of the Tymoviridae family that infect grapevines in the Czech Republic. Complete sequences of GFkV (grapevine fleck virus) and GRGV (grapevine red globe virus) from the genus Maculavirus and GRVFV (grapevine rupestris vein feathering virus) and GSyV-1 (grapevine Syrah virus 1) from the genus Marafivirus were obtained using high-throughput sequencing of small RNAs and total RNAs. Mixed infections with these viruses were observed, as well as several variants of these viruses in the same plant. Phylogenetic analysis showed the position of the newly obtained virus isolates within the Tymoviridae family. Recombinant analysis provided evidence of single and multiple intraspecific recombinations in GRGV, GSyV-1, and GRVFV. Additionally, GAMaV, a grapevine virus from the genus Marafivirus, was reported for the first time in the Czech Republic.


Assuntos
Tymoviridae , Filogenia , República Tcheca , Doenças das Plantas
7.
Korean J Ophthalmol ; 38(2): 113-121, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38351484

RESUMO

PURPOSE: To investigate cases of vitreous opacity (VO) similar to asteroid hyalosis (AH) after intravitreal brolucizumab injection. METHODS: A retrospective chart review was conducted to identify cases showing VO similar to AH among patients who received intravitreal brolucizumab injections at our retinal clinic from January 2022 to January 2023. RESULTS: A total of 220 brolucizumab injections were administered at our hospital. VO, showing yellow-white brilliant reflective particles, was found in six patients (2.7%). When VO occurred, all patients complained of floaters, although none of them complained of other symptoms including decreased visual acuity, pain, or conjunctival redness. The mean number of brolucizumab injections was 2.57 ± 2.38. No significant visual impairment was observed while VO was present. VO improved in all cases, and four cases improved without any treatment. The mean interval from onset to disappearance of VO was 8.0 ± 3.1 weeks. CONCLUSIONS: VO, similar to AH, can occur with a relatively high probability after intravitreal brolucizumab injections. Patients complained of severe floaters, but VO was not accompanied by other symptoms including vision impairment, injection, and pain. The VO disappeared after approximately 4 to 14 weeks. In case that other inflammatory findings are not severe, close follow-up without treatment may be sufficient. If a patient complains of floaters after an intravitreal brolucizumab injection, close fundus observation is necessary to evaluate the VO.


Assuntos
Anticorpos Monoclonais Humanizados , Doenças Orbitárias , Transtornos da Visão , Humanos , Estudos Retrospectivos , Injeções Intravítreas , Dor , Inibidores da Angiogênese
8.
Ophthalmol Ther ; 13(3): 791-800, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38244181

RESUMO

INTRODUCTION: The aim of this study was to analyze posterior surface opacification in explanted silicone intraocular lenses (IOLs) with clinicopathologic correlation to asteroid hyalosis. METHODS: In a laboratory setup, 12 explanted silicone IOLs underwent laboratory analyses, including light microscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy for elemental composition (EDX). Relevant clinical data were obtained for each case, including gender, age at IOL implantation, dates of implantation and explantation, as well as history of neodymium-dopped yttrium aluminum garnet (Nd:YAG) laser treatments or other opacification removal attempts. High-resolution optical coherence tomography (OCT) images were obtained in vitro with an anterior segment OCT device (Anterion, Heidelberg Engineering, Heidelberg, Germany). RESULTS: Calcification located at the posterior optic surface of each lens was identified through SEM and EDX analyses, revealing deposits composed of hydroxyapatite. In all cases, IOL polishing using Nd:YAG laser had been attempted prior to IOL exchange. The clinical functional data showed that this type of IOL opacity led to increase in straylight and subjective symptoms of glare. CONCLUSIONS: Silicone IOLs can develop posterior surface calcification in eyes with asteroid hyalosis. There are mechanical techniques of cleaning the IOL surface but in many cases, IOL explantation is the only sustainable way to reduce the patients' straylight levels and glare symptoms. Due to the risk of posterior surface calcification, silicone IOL implantation should be avoided in eyes with asteroid hyalosis.

9.
Space Sci Rev ; 220(1): 1, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38130909

RESUMO

The Lucy Thermal Emission Spectrometer (L'TES) will provide remote measurements of the thermophysical properties of the Trojan asteroids studied by the Lucy mission. L'TES is build-to-print hardware copy of the OTES instrument flown on OSIRIS-REx. It is a Fourier Transform spectrometer covering the spectral range 5.71-100 µm (1750-100 cm-1) with spectral sampling intervals of 8.64, 17.3, and 34.6 cm-1 and a 7.3-mrad field of view. The L'TES telescope is a 15.2-cm diameter Cassegrain telescope that feeds a flat-plate Michelson moving mirror mounted on a linear voice-coil motor assembly to a single uncooled deuterated l-alanine doped triglycine sulfate (DLATGS) pyroelectric detector. A significant firmware change from OTES is the ability to acquire interferograms of different length and spectral resolution with acquisition times of 0.5, 1, and 2 seconds. A single ∼0.851 µm laser diode is used in a metrology interferometer to provide precise moving mirror control and IR sampling at 772 Hz. The beamsplitter is a 38-mm diameter, 1-mm thick chemical vapor deposited diamond with an antireflection microstructure to minimize surface reflection. An internal calibration cone blackbody target, together with observations of space, provides radiometric calibration. The radiometric precision in a single spectrum is ≤2.2 × 10-8 W cm-2 sr-1 /cm-1 between 300 and 1350 cm-1. The absolute temperature error is <2 K for scene temperatures >75 K. The overall L'TES envelope size is 37.6 × 29.0 × 30.4 cm, and the mass is 6.47 kg. The power consumption is 12.6 W average. L'TES was developed by Arizona State University with AZ Space Technologies developing the electronics. L'TES was integrated, tested, and radiometrically calibrated on the Arizona State University campus in Tempe, AZ. Initial data from space have verified the instrument's radiometric and spatial performance.

10.
J Vet Med Sci ; 85(10): 1131-1135, 2023 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-37612056

RESUMO

Five pigs experimentally infected with Actinobacillus pleuropneumoniae serovar 15 isolated in our previous study were pathologically examined. One pig died at 2 days post inoculation (dpi) and four pigs were euthanized at 7 dpi. Autopsy revealed fibrinohemorrhagic pleuropneumonia in all pigs. Histopathologically, the lesions were characterized by extensive hemorrhage and necrosis, fibrin deposition, and multifocal abscesses composed of numerous neutrophils including oat cells and numerous Gram-negative bacilli. In one survived pig, asteroid body formation was confirmed in the lung. The bacteria within the abscesses and asteroid bodies were immunohistochemically positive for antiserum raised against A. pleuropneumoniae serovar 15. This is the first report describing porcine pleuropneumonia with asteroid bodies in a pig experimentally infected with A. pleuropneumoniae serovar 15.


Assuntos
Infecções por Actinobacillus , Actinobacillus pleuropneumoniae , Mycoplasma , Pleuropneumonia , Doenças dos Suínos , Suínos , Animais , Pleuropneumonia/microbiologia , Pleuropneumonia/veterinária , Sorogrupo , Abscesso/patologia , Abscesso/veterinária , Infecções por Actinobacillus/microbiologia , Infecções por Actinobacillus/veterinária , Doenças dos Suínos/microbiologia , Pulmão/patologia
11.
Int J Mol Sci ; 24(15)2023 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-37569405

RESUMO

Symmetries have not been completely determined and explained from the discovery of the DNA structure in 1953 and the genetic code in 1961. We show, during 10 years of investigation and research, our discovery of the Supersymmetry Genetic Code table in the form of 2 × 8 codon boxes, quadruplet DNA symmetries, and the classification of trinucleotides/codons, all built with the same physiochemical double mirror symmetry and Watson-Crick pairing. We also show that single-stranded RNA had the complete code of life in the form of the Supersymmetry Genetic Code table simultaneously with instructions of codons' relationship as to how to develop the DNA molecule on the principle of Watson-Crick pairing. We show that the same symmetries between the genetic code and DNA quadruplet are highly conserved during the whole evolution even between phylogenetically distant organisms. In this way, decreasing disorder and entropy enabled the evolution of living beings up to sophisticated species with cognitive features. Our hypothesis that all twenty amino acids are necessary for the origin of life on the Earth, which entirely changes our view on evolution, confirms the evidence of organic natural amino acids from the extra-terrestrial asteroid Ryugu, which is nearly as old as our solar system.


Assuntos
DNA , Código Genético , DNA/genética , Códon/genética , Aminoácidos/genética , RNA , Evolução Molecular
12.
Life (Basel) ; 13(7)2023 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-37511823

RESUMO

The Hayabusa2 mission was tasked with returning samples from the C-complex asteroid Ryugu (1999 JU3), in order to shed light on the formation, evolution and composition of such asteroids. One of the main science objectives was to understand whether such bodies could have supplied the organic matter required for the origin of life on Earth. Here, a review of the studies concerning the organic matter within the Ryugu samples is presented. This review will inform the reader about the Hayabusa2 mission, the nature of the organic matter analyzed and the various interpretations concerning the analytical findings including those concerning the origin and evolution of organic matter from Ryugu. Finally, the review puts the findings and individual interpretations in the context of the current theories surrounding the formation and evolution of Ryugu. Overall, the summary provided here will help to inform those operating in a wide range of interdisciplinary fields, including planetary science, astrobiology, the origin of life and astronomy, about the most recent developments concerning the organic matter in the Ryugu return samples and their relevance to understanding our solar system and beyond. The review also outlines the issues that still remain to be solved and highlights potential areas for future work.

13.
Clin Ophthalmol ; 17: 1739-1754, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37361691

RESUMO

Asteroid hyalosis (AH) is a benign clinical entity characterized by the presence of multiple refractile spherical calcium and phospholipids within the vitreous body. First described by Benson in 1894, this entity has been well documented in the clinical literature and is named due to the resemblance of asteroid bodies on clinical examination to a starry night sky. Today, a growing body of epidemiologic data estimates the global prevalence of asteroid hyalosis to be around 1%, and there is a strong established association between AH and older age. While pathophysiology remains unclear, a variety of systemic and ocular risk factors for AH have recently been suggested in the literature and may provide insight into possible mechanisms for asteroid body (AB) development. As vision is rarely affected, clinical management is focused on differentiation of asteroid hyalosis from mimicking conditions, evaluation of the underlying retina for other pathology and consideration of vitrectomy in rare cases with visual impairment. Taking into account the recent technologic advances in large-scale medical databases, improving imaging modalities, and the popularity of telemedicine, this review summarizes the growing body of literature of AH epidemiology and pathophysiology and provides updates on the clinical diagnosis and management of AH.

14.
Insects ; 14(6)2023 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-37367365

RESUMO

Nuclease is a type of protein that degrades nucleic acids, which plays an important role in biological processes, including RNA interference efficiency and antiviral immunity. However, no evidence of a link between nuclease and Bombyx mori nucleopolyhedrovirus (BmNPV) infection in silkworm B. mori has been found. In this study, a protein asteroid (BmAst) containing the PIN domain and XPG domain was identified in silkworm B. mori. BmAst gene was highest expressed in hemocytes and fat body of the 5th instar larvae, and high expression in the pupa stage. The transcriptional levels of the BmAst gene in 5th instar larvae were significantly induced by BmNPV or dsRNA. After knocking down BmAst gene expression by specific dsRNA, the proliferation of BmNPV in B. mori was increased significantly, whereas the survival rate of larvae was significantly lower when compared with the control. Our findings indicate that BmAst is involved in silkworm resistance to BmNPV infection.

15.
Case Rep Ophthalmol ; 14(1): 245-249, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37383168

RESUMO

A 70-year-old male presented for cataract surgery in the right eye with pre-operative assessment significant for nuclear sclerotic cataract and asteroid hyalosis. Upon irrigation and aspiration during cataract surgery, yellow-white spheres consistent with asteroid hyalosis were visualized circulating into the anterior chamber despite an intact capsule and no apparent zonular weakness. The asteroides particles were completely aspirated by the irrigation and aspiration ports, and an intraocular lens was implanted into the capsular bag. Postoperatively, the patient did well with final visual acuity of 20/20 and no vitreous prolapse, retinal tears, or detachments noted. There are only four cases in the literature of asteroid hyalosis migrating in the anterior chamber; none of these cases are associated with migration during intraocular surgery. We hypothesize that the asteroid hyalosis migrated anteriorly and around the zonules due to the synuretic nature of the vitreous and microscopic gaps in the zonular fibers. This case demonstrates the importance of the cataract surgeon to be aware of potential migration of asteroid hyalosis into the anterior chamber during surgery.

16.
Astrobiology ; 23(6): 670-690, 2023 06.
Artigo em Inglês | MEDLINE | ID: mdl-37229534

RESUMO

Silicate spherules have been identified from the ca. 3.4 Ga-old Strelley Pool Formation (SPF) in the Pilbara Craton, Western Australia. Their origins and geochemical characteristics, including the Re and platinum-group elements of their host clastic layer and the overlying and underlying microfossil-bearing finely laminated carbonaceous cherts, were examined. The spherules have various morphologies (completely spherical to angular), sizes (∼20 to >500 µm), textures (layered, non-layered, and fibrous), mineralogy (various proportions of microcrystalline quartz, sericite, anatase and Fe-oxides), and chemistry (enriched in Ni and/or Cr), commonly with thin anatase-rich walls. Their host clastic layer is characterized by rip-up clasts, suggesting a suddenly occurring high-energy depositional environment, such as tsunamis. Although various origins other than asteroid impact were considered, none could unequivocally explain the features of the spherules. In contrast, non-layered spherical spherules that occur as individual framework grains or collectively comprise angular-shaped rock fragments appear to be more consistent with the asteroid impact origin. The calculated Re-Os age of the cherts (3331 ± 220 Ma) was consistent with the established age of the SPF (3426-3350 Ma), suggesting that the Re-Os system was not significantly disturbed by later metamorphic and weathering events.


Assuntos
Sedimentos Geológicos , Platina , Austrália Ocidental , Sedimentos Geológicos/química , Silicatos
17.
Space Sci Rev ; 219(3): 25, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37034007

RESUMO

The NASA Psyche mission's program to engage university undergraduates and the public in the mission is inspired by and built upon the extensive foundation of public engagement, educational outreach activities, and expertise of NASA and mission partner institutions. The program leverages the enthusiasm and contributions of undergraduates nationwide to the benefit of the mission, the students and their institutions and communities, and the broader public. Psyche Student Collaborations consists of four main programs, two (Psyche Capstone and Psyche Inspired) are available solely to undergraduates enrolled at universities or community colleges in the United States and its territories and two (Innovation Toolkit free online courses and Science Outreach Interns and Docents) invite broader participation by engaging the talents and creativity of undergraduate interns to help create content and events to reach the public and lifelong learners. Together, these offerings provide multiple entry points and a spectrum of intensity of experiences, numbers of participants, disciplinary diversity, and mode of delivery. Involving undergraduates in all phases of the program supports the development of the next generation of explorers, contributes to the nation's workforce preparation, and complements NASA's existing undergraduate offerings by providing long-term opportunities for students to participate with the mission through established postsecondary education structures like capstone courses.

18.
Nat Hazards (Dordr) ; 116(2): 1355-1402, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36776703

RESUMO

Modern civilization has no collective experience with possible wide-ranging effects from a medium-sized asteroid impactor. Currently, modeling efforts that predict initial effects from a meteor impact or airburst provide needed information for initial preparation and evacuation plans, but longer-term cascading hazards are not typically considered. However, more common natural disasters, such as volcanic eruptions, earthquakes, wildfires, dust storms, and hurricanes, are likely analogs that can provide the scope and scale of these potential effects. These events, especially the larger events with cascading effects, are key for understanding the scope and complexity of mitigation, relief, and recovery efforts for a medium-sized asteroid impact event. This paper reviews the initial and cascading effects of these natural hazards, describes the state of the art for modeling these hazards, and discusses the relevance of these hazards to expected long-term effects of an asteroid impact. Emergency managers, resource managers and planners, and research scientists involved in mitigation and recovery efforts would likely derive significant benefit from a framework linking multiple hazard models to provide a seamless sequence of related forecasts.

19.
Proc Natl Acad Sci U S A ; 120(5): e2214353120, 2023 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-36689662

RESUMO

Rubble piles asteroids consist of reassembled fragments from shattered monolithic asteroids and are much more abundant than previously thought in the solar system. Although monolithic asteroids that are a kilometer in diameter have been predicted to have a lifespan of few 100 million years, it is currently not known how durable rubble pile asteroids are. Here, we show that rubble pile asteroids can survive ambient solar system bombardment processes for extremely long periods and potentially 10 times longer than their monolith counterparts. We studied three regolith dust particles recovered by the Hayabusa space probe from the rubble pile asteroid 25143 Itokawa using electron backscatter diffraction, time-of-flight secondary ion mass spectrometry, atom probe tomography, and 40Ar/39Ar dating techniques. Our results show that the particles have only been affected by shock pressure of ca. 5 to 15 GPa. Two particles have 40Ar/39Ar ages of 4,219 ± 35 and 4,149 ± 41 My and when combined with thermal and diffusion models; these results constrain the formation age of the rubble pile structure to ≥4.2 billion years ago. Such a long survival time for an asteroid is attributed to the shock-absorbent nature of rubble pile material and suggests that rubble piles are hard to destroy once they are created. Our results suggest that rubble piles are probably more abundant in the asteroid belt than previously thought and provide constrain to help develop mitigation strategies to prevent asteroid collisions with Earth.


Assuntos
Poeira , Planeta Terra , Difusão , Elétrons , Longevidade
20.
Int J Surg Pathol ; 31(6): 1099-1104, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-36314437

RESUMO

Silicone breast implants are frequently used for breast augmentation for cosmetic purposes, as well as for breast reconstruction after prophylactic or therapeutic mastectomy. Silicone lymphadenopathy is a well-known complication of silicone breast implants. Silicone droplets are present in the breast tissue through 'silicone bleeding' of the implant or because of implant rupture. These silicone particles can migrate from the breast to the regional lymph nodes. Silicone lymphadenopathy is caused by a substantial foreign body reaction against these silicone particles, and is frequently associated with asteroid body-containing multinucleated giant cells. Similar multinucleated giant cells are often observed in the capsule surrounding the silicone breast implant, and the number of associated asteroid bodies is highly variable. Here, we discuss a series of twelve women with breast implant-related asteroid bodies in their lymph nodes and/or breast tissue. This pictorial essay illustrates that the presence of asteroid bodies in a lymph node does not necessarily suggests a diagnosis of sarcoidosis. Clinical information about the patient having (or having had) silicone breast implants is often lacking. The encounter of asteroid body-containing giant cells in lymph node cytology, biopsies or resections should therefore lead to reflex clinical-pathological correlation, before establishing a final diagnosis.


Assuntos
Implantes de Mama , Neoplasias da Mama , Linfadenopatia , Doenças Linfáticas , Sarcoidose , Feminino , Humanos , Implantes de Mama/efeitos adversos , Géis de Silicone/efeitos adversos , Doenças Linfáticas/diagnóstico , Doenças Linfáticas/etiologia , Doenças Linfáticas/patologia , Neoplasias da Mama/diagnóstico , Neoplasias da Mama/cirurgia , Neoplasias da Mama/complicações , Mastectomia , Linfadenopatia/etiologia , Linfadenopatia/complicações , Sarcoidose/diagnóstico , Sarcoidose/complicações
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