RESUMO
Establishing when, and from where, carbon, nitrogen and water were delivered to Earth is a fundamental objective in understanding the origin of habitable planets such as Earth. Yet, volatile delivery to Earth remains controversial1-5. Krypton isotopes provide insights on volatile delivery owing to their substantial isotopic variations among sources6-10, although pervasive atmospheric contamination has hampered analytical efforts. Here we present the full suite of krypton isotopes from the deep mantle of the Galápagos and Iceland plumes, which have the most primitive helium, neon and tungsten isotopic compositions11-16. Except for 86Kr, the krypton isotopic compositions are similar to a mixture of chondritic and atmospheric krypton. These results suggest early accretion of carbonaceous material by proto-Earth and rule out any combination of hydrodynamic loss with outgassing of the deep or shallow mantle to explain atmospheric noble gases. Unexpectedly, the deep-mantle sources have a deficit in the neutron-rich 86Kr relative to the average composition of carbonaceous meteorites, which suggests a nucleosynthetic anomaly. Although the relative depletion of neutron-rich isotopes on Earth compared with carbonaceous meteorites has been documented for a range of refractory elements1,17,18, our observations suggest such a depletion for a volatile element. This finding indicates that accretion of volatile and refractory elements occurred simultaneously, with krypton recording concomitant accretion of non-solar volatiles from more than one type of material, possibly including outer Solar System planetesimals.
Assuntos
Carbono/análise , Planeta Terra , Evolução Planetária , Sedimentos Geológicos/química , Criptônio/análise , Atmosfera/química , Equador , Evolução Química , Hélio/análise , Islândia , Isótopos/análise , Meteoroides , Neônio/análise , Nêutrons , Nitrogênio/análise , Tungstênio/análise , Xenônio/análiseRESUMO
Combined coarse-grained (CG) and atomistic molecular dynamics (MD) simulations were performed to study the interactions of xenon with model lipid rafts consisting of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) and cholesterol (Chol). At a concentration of 2 Xe/lipid we observed an unexpected result: spontaneous nucleation of Xe nano bubbles which rapidly plunged into the bilayer. In this process Chol, essential for raft stabilization, was pulled out from the raft into the hydrophobic zone. When concentration was further increased (3 Xe/lipid), the bubbles increase in size and disrupted both the membrane and raft. We computed the radial distribution functions, pair-wise potentials, second virial coefficients and Schlitter entropy to scrutinize the nature of the interactions. Our findings, concurring with a recent report on the origin of general anaesthesia (M. A. Pavel, E. N. Petersen, H. Wang, R. A. Lerner and S. B. Hansen, Proc. Natl. Acad. Sci. U. S. A., 2020, 117(24), 13757-13766), suggest that the well-known anaesthetic effect of Xe could be mediated by sequestration of Chol, which, in turn, compromises the stability of rafts where specialized proteins needed to produce the nervous signal are anchored.
Assuntos
Bicamadas Lipídicas , Fosfatidilcolinas , Colesterol , Microdomínios da Membrana , XenônioRESUMO
Ultraviolet (UV) light has destructive activity against pathogenic bacteria including Clostridioides difficile spores. Portable pulsed-xenon UV disinfecting devices were implemented for terminal room cleaning in 6 units of our academic hospital with high C. difficile infection (CDI) rates. CDI rates were measured in a 9-month period before and a 9-month period after device implementation. Despite documented administration of UV disinfection for 87% of terminal room cleaning, no impact on CDI rates was detected.
Assuntos
Clostridioides difficile , Infecção Hospitalar , Raios Ultravioleta , Clostridioides , Infecção Hospitalar/prevenção & controle , Atenção à Saúde , Desinfecção , Humanos , Centros de Atenção Terciária , XenônioRESUMO
BACKGROUND: Hospital environment in patient care has been linked on healthcare-associated infections (HAI). No touch disinfection technologies that utilize pulsed xenon ultraviolet light has been recognized to prevent infection in contaminated environments. The purpose of this study was: 1) to evaluate the effectiveness of pulsed-xenon ultraviolet light (PX-UV) disinfection for the reduction of bacteria on environmental surfaces of Hospital General Enrique Garcés, and 2) to evaluate the in-vitro efficacy against multi-drug resistance microorganisms. METHODS: This was a quality-improvement study looking at cleaning and disinfection of patient areas. During the study, a total of 146 surfaces from 17 rooms were sampled in a secondary 329-bed public medical center. Microbiological samples of high-touch surfaces were taken after terminal manual cleaning and after pulsed xenon ultraviolet disinfection. Cleaning staff were blinded to the study purpose and told clean following their usual protocols. For positive cultures PCR identification for carbapenemase-resistance genes (blaKPC, blaIMP, blaVIM, and blaNDM) were analyzed and confirmed by sequencing. The total number of colony forming units (CFU) were obtained and statistical analyses were conducted using Wilcoxon Rank Sum tests to evaluate the difference in CFU between terminal manual cleaning and after pulsed xenon ultraviolet disinfection. RESULTS: After manual disinfection of 124 surfaces showed a total of 3569 CFU which dropped to 889 CFU in 80 surfaces after pulsed xenon disinfection (p < 0.001). Overall, the surface and environmental contamination was reduced by 75% after PX-UV compared to manual cleaning and disinfection. There were statistically significant decreases in CFU counts of high touch surfaces in OR 87% (p < 0.001) and patient rooms 76% (p < 0.001). Four rooms presented serine carbapenemases blaKPC, and metallo beta-lactamases blaNDM, blaVIM, blaIMP. confirmed by PCR and sequencing. The in-vitro testing with endemic strains found that after five minutes of pulsed xenon ultraviolet exposure an 8-log reduction was achieved in all cases. CONCLUSION: This study is one of the first of its kind in an Ecuador Hospital. We found that pulsed-xenon ultraviolet disinfection technology is an efficacious complement to the established manual cleaning protocols and guidelines in the significant reduction of MDRO.
Assuntos
Desinfecção/métodos , Hospitais , Bactérias/genética , Proteínas de Bactérias/genética , Contagem de Colônia Microbiana , Infecção Hospitalar/prevenção & controle , Desinfecção/instrumentação , Farmacorresistência Bacteriana/genética , Equador , Humanos , Quartos de Pacientes , Raios Ultravioleta , Xenônio , beta-Lactamases/genéticaRESUMO
Abstract The subject of the study was the stability of human white blood cell membranes subject to noble gases (xenon ad krypton, 0.6 mPa) clathrate cryoanabiosis (‒80°C). A unique portable stainless steel low pressure container with a compartment for flexible plastic container was designed to ensure that the cells are saturated with gases. The samples were warmed after 1 and 30 days in a water bath (+38°C) for 35-50 sec, while the container was being tilted (2-3 times per second), until the temperature of the biological object reached +3±1°C. It was demonstrated that after 30 days of clathrate anabiosis (-80°C) over 95% (of the original number) of leukocytes remain viable, and cell membranes of 54.5±3.4% of them is resistant to trypan blue; granulocyte survival rate is 73.5±2.7%, original lipid peroxidation rate and antioxidant activity are retained. Biological object cryopreservation in noble gases environment is a promising trend in biology and medicine.
Assuntos
Xenônio , Criopreservação , Leucócitos , Células Sanguíneas , CriptônioRESUMO
The low survival of insect-pathogenic fungi when used for insect control in agriculture is mainly due to the deleterious effects of ultraviolet radiation and heat from solar irradiation. In this study, conidia of 15 species of entomopathogenic fungi were exposed to simulated full-spectrum solar radiation emitted by a Xenon Test Chamber Q-SUN XE-3-HC 340S (Q-LAB® Corporation, Westlake, OH, USA), which very closely simulates full-spectrum solar radiation. A dendrogram obtained from cluster analyses, based on lethal time 50 % and 90 % calculated by Probit analyses, separated the fungi into three clusters: cluster 3 contains species with highest tolerance to simulated full-spectrum solar radiation, included Metarhizium acridum, Cladosporium herbarum, and Trichothecium roseum with LT50 > 200 min irradiation. Cluster 2 contains eight species with moderate UV tolerance: Aschersonia aleyrodis, Isaria fumosorosea, Mariannaea pruinosa, Metarhizium anisopliae, Metarhizium brunneum, Metarhizium robertsii, Simplicillium lanosoniveum, and Torrubiella homopterorum with LT50 between 120 and 150 min irradiation. The four species in cluster 1 had the lowest UV tolerance: Lecanicillium aphanocladii, Beauveria bassiana, Tolypocladium cylindrosporum, and Tolypocladium inflatum with LT50 < 120 min irradiation. The QSUN Xenon Test Chamber XE3 is often used by the pharmaceutical and automotive industry to test light stability and weathering, respectively, but it was never used to evaluate fungal tolerance to full-spectrum solar radiation before. We conclude that the equipment provided an excellent tool for testing realistic tolerances of fungi to full-spectrum solar radiation of microbial agents for insect biological control in agriculture.
Assuntos
Entomophthorales/efeitos dos fármacos , Entomophthorales/crescimento & desenvolvimento , Tolerância a Radiação , Energia Solar , Luz Solar , Raios Ultravioleta , XenônioRESUMO
The synthesis of nanoparticles is usually carried out by chemical reduction, which is effective but uses many toxic substances, making the process potentially harmful to the environment. Hence, as part of the search for environmentally friendly or green synthetic methods, this study aimed to produce silver nanoparticles (AgNPs) using only AgNO3, Milli-Q water, white light from a xenon lamp (Xe) and amino acids. Nanoparticles were synthetized using 21 amino acids, and the shapes and sizes of the resultant nanoparticles were evaluated. The products were characterized by UV-Vis, zeta potential measurements and transmission electron microscopy. The synthesis of silver nanoparticles with tryptophan and tyrosine, methionine, cystine and histidine was possible through photoreduction method. Spherical nanoparticles were produced, with sizes ranging from 15 to 30 nm. Tryptophan does not require illumination nor heating, and the solution color changes immediately after the mixing of reagents if sodium hydroxide is added to the solution (pH = 10). The Xe illumination acts as sodium hydroxide in the nanoparticles synthesis, releases H+ and allows the reduction of silver ions (Ag+) in metallic silver (Ag0).
Assuntos
Aminoácidos/química , Química Verde/métodos , Nanopartículas Metálicas/química , Prata/química , Materiais Biocompatíveis/síntese química , Materiais Biocompatíveis/química , Concentração de Íons de Hidrogênio , Microscopia Eletrônica de Transmissão , Nitrato de Prata/química , Espectrofotometria Ultravioleta , Temperatura , Triptofano/química , XenônioRESUMO
OBJECTIVES: The anesthetic gas xenon is reported to preserve hemodynamic stability during general anesthesia. However, the effects of the gas during shock are unclear. The objective of this study was to evaluate the effect of Xe on hemodynamic stability and tissue perfusion in a canine model of hemorrhagic shock. METHOD: Twenty-six dogs, mechanically ventilated with a fraction of inspired oxygen of 21% and anesthetized with etomidate and vecuronium, were randomized into Xenon (Xe; n = 13) or Control (C; n = 13) groups. Following hemodynamic monitoring, a pressure-driven shock was induced to reach an arterial pressure of 40 mmHg. Hemodynamic data and blood samples were collected prior to bleeding, immediately after bleeding and 5, 20 and 40 minutes following shock. The Xe group was treated with 79% Xe diluted in ambient air, inhaled for 20 minutes after shock. RESULT: The mean bleeding volume was 44 mL.kg-1 in the C group and 40 mL.kg-1 in the Xe group. Hemorrhage promoted a decrease in both the cardiac index (p<0.001) and mean arterial pressure (p<0.001). These changes were associated with an increase in lactate levels and worsening of oxygen transport variables in both groups (p<0.05). Inhalation of xenon did not cause further worsening of hemodynamics or tissue perfusion markers. CONCLUSIONS: Xenon did not alter hemodynamic stability or tissue perfusion in an experimentally controlled hemorrhagic shock model. However, further studies are necessary to validate this drug in other contexts.
Assuntos
Anestésicos Inalatórios/farmacologia , Hemodinâmica/efeitos dos fármacos , Modelos Animais , Choque Hemorrágico , Xenônio/farmacologia , Animais , Cães , Masculino , Perfusão , Distribuição Aleatória , Respiração/efeitos dos fármacos , Fatores de Tempo , Resultado do TratamentoRESUMO
OBJECTIVES: The anesthetic gas xenon is reported to preserve hemodynamic stability during general anesthesia. However, the effects of the gas during shock are unclear. The objective of this study was to evaluate the effect of Xe on hemodynamic stability and tissue perfusion in a canine model of hemorrhagic shock. METHOD: Twenty-six dogs, mechanically ventilated with a fraction of inspired oxygen of 21% and anesthetized with etomidate and vecuronium, were randomized into Xenon (Xe; n = 13) or Control (C; n = 13) groups. Following hemodynamic monitoring, a pressure-driven shock was induced to reach an arterial pressure of 40 mmHg. Hemodynamic data and blood samples were collected prior to bleeding, immediately after bleeding and 5, 20 and 40 minutes following shock. The Xe group was treated with 79% Xe diluted in ambient air, inhaled for 20 minutes after shock. RESULT: The mean bleeding volume was 44 mL.kg-1 in the C group and 40 mL.kg-1 in the Xe group. Hemorrhage promoted a decrease in both the cardiac index (p<0.001) and mean arterial pressure (p<0.001). These changes were associated with an increase in lactate levels and worsening of oxygen transport variables in both groups (p<0.05). Inhalation of xenon did not cause further worsening of hemodynamics or tissue perfusion markers. CONCLUSIONS: Xenon did not alter hemodynamic stability or tissue perfusion in an experimentally controlled hemorrhagic shock model. However, further studies are necessary to validate this drug in other contexts.