Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 497
Filtrar
1.
J Chem Inf Model ; 63(21): 6706-6716, 2023 11 13.
Artigo em Inglês | MEDLINE | ID: mdl-37907068

RESUMO

Modeling of complex liquids at solid surfaces and in confinement is gaining attention due to an increase in computer power and advancement of simulation techniques. Therefore, tools to set up structures and for analysis are needed. In this paper, we present CONAN─a Python code designed to facilitate the study of liquids interacting with solid structures, such as walls or pores. Among other things, the program provides the option to generate a variety of different structures, including carbon walls and nanotubes and their boron nitride analogs, as well as the ability to analyze various structural properties of confined and interfacial liquids. In the case of the ionic liquid 1-butyl-3-methylimidazolium acetate in carbon nanotubes of different sizes, we demonstrate the abilities of our tool. The average density within the confinement highly depends on the carbon nanotube size, and it is generally lower than the density of the bulk liquid. The arrangement of the individual species within the tube also depends on size, with radial layers forming within the tubular confinement. The density is largely increased in the respective layers, while it is drastically reduced between the layers.


Assuntos
Líquidos Iônicos , Nanotubos de Carbono , Nanotubos de Carbono/química , Espaços Confinados , Líquidos Iônicos/química
2.
Mol Biol Cell ; 34(12): ar122, 2023 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-37672340

RESUMO

The invasive potential of glioblastoma cells is attributed to large changes in pressure and volume, driven by diverse elements, including the cytoskeleton and ion cotransporters.  However, how the cell actuates changes in pressure and volume in confinement, and how these changes contribute to invasive motion is unclear. Here, we inhibited SPAK activity, with known impacts on the cytoskeleton and cotransporter activity and explored its role on the migration of glioblastoma cells in confining microchannels to model invasive spread through brain tissue. First, we found that confinement altered cell shape, inducing a transition in morphology that resembled droplet interactions with a capillary vessel, from "wetting" (more adherent) at low confinement, to "nonwetting" (less adherent) at high confinement. This transition was marked by a change from negative to positive pressure by the cells to the confining walls, and an increase in migration speed. Second, we found that the SPAK pathway impacted the migration speed in different ways dependent upon the extent of wetting. For nonwetting cells, SPAK inhibition increased cell-surface tension and cotransporter activity. By contrast, for wetting cells, it also reduced myosin II and YAP phosphorylation. In both cases, membrane-to-cortex attachment is dramatically reduced. Thus, our results suggest that SPAK inhibition differentially coordinates cotransporter and cytoskeleton-induced forces, to impact glioblastoma migration depending on the extent of confinement.


Assuntos
Glioblastoma , Humanos , Glioblastoma/metabolismo , Espaços Confinados , Citoesqueleto/metabolismo , Fosforilação , Microtúbulos/metabolismo
3.
Zhonghua Wei Zhong Bing Ji Jiu Yi Xue ; 35(7): 777-781, 2023 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-37545462

RESUMO

Major natural disasters seriously threaten human life and health. After earthquakes and other catastrophes, survivors are often trapped in the confined spaces caused by the collapse of ground and buildings, with relative separation from the outside world, restricted access, complex environment, and oncoming or ongoing unsafety, leading to the rescue extremely difficult. In order to save lives and improve the outcome more efficiently in the confined spaces after natural disasters, it is very important to standardize and reasonably apply the trauma assessment and first aid workflow. This study focuses on trauma assessment and first aid. From the aspects of trauma assessment, vital signs stabilization, hemostasis and bandaging, post-trauma anti-infection, and the transportation of patients, a trauma first aid work process suitable for a small space of a major natural disaster is formed, It is helpful to realize the immediate and efficient treatment of trauma in the confined spaces after natural catastrophes, to reduce the rate of death and disability and improve the outcome of patients.


Assuntos
Desastres , Terremotos , Humanos , Primeiros Socorros , Espaços Confinados
4.
Angew Chem Int Ed Engl ; 62(26): e202304303, 2023 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-37130008

RESUMO

One striking feature of enzyme is its controllable ability to trap substrates via synergistic or cooperative binding in the enzymatic pocket, which renders the shape-selectivity of product by the confined spatial environment. The success of shape-selective catalysis relies on the ability of enzyme to tune the thermodynamics and kinetics for chemical reactions. In emulation of enzyme's ability, we showcase herein a targeting strategy with the substrate being anchored on the internal pore wall of metal-organic frameworks (MOFs), taking full advantage of the sterically kinetic control to achieve shape-selectivity for the reactions. For this purpose, a series of binding site-accessible metal metalloporphyrin-frameworks (MMPFs) have been investigated to shed light on the nature of enzyme-mimic catalysis. They exhibit a different density of binding sites that are well arranged into the nanospace with corresponding distances of opposite binding sites. Such a structural specificity results in a facile switch in selectivity from an exclusive formation of the thermodynamically stable product to the kinetic product. Thus, the proposed targeting strategy, based on the combination of porous materials and binding events, paves a new way to develop highly efficient heterogeneous catalysts for shifting selectivity.


Assuntos
Metaloporfirinas , Metaloporfirinas/química , Espaços Confinados , Cinética , Sítios de Ligação , Catálise
5.
J Occup Environ Hyg ; 20(8): 322-328, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-37159506

RESUMO

In 2022, a confined space entry accident occurred on a Danish product tanker in which two technicians died from hydrogen sulfide poisoning during the inspection of an empty cargo tank that had contained vegetable cooking oil. The source of the hydrogen sulfide was enigmatic. About three weeks before the accident, the cargo tank was prewashed with seawater. The wash water did not seem likely to present a toxic hazard and was left in the tank. However, the seawater's natural content of dissolved sulfate was converted to sulfide by sulfate-reducing bacteria, and the low-sulfur vegetable oil residue provided the nutrients necessary for bacterial growth. Calculations confirm that sulfate in just 10 m3 of plain seawater is sufficient to create an immediately fatal concentration of H2S gas in the 4,500 m3 cargo tank of the product tanker. Accident statistics show that fatal accidents within enclosed spaces are a serious and stubborn problem. Strict adherence to routine forced ventilation and extensive gas testing of cargo tanks before entry would offer simple and effective preventive measures.


Assuntos
Sulfeto de Hidrogênio , Espaços Confinados , Sulfetos , Água do Mar , Sulfatos
6.
Nano Lett ; 23(10): 4439-4447, 2023 05 24.
Artigo em Inglês | MEDLINE | ID: mdl-37166380

RESUMO

The binding of ligands to receptors within a nanoscale small space is relevant in biology, biosensing, and affinity filtration. Binding in confinement can be studied with biological systems but under the limitation that essential parameters cannot be easily controlled including receptor type and position within the confinement and its dimensions. Here we study molecular recognition with a synthetic confined nanopore with controllable pore dimension and molecular DNA receptors at different depth positions within the channel. Binding of a complementary DNA strand is studied at the single-molecule level with atomic force microscopy. Following the analysis, kinetic association rates are lower for receptors positioned deeper inside the pore lumen while dissociation is faster and requires less force. The phenomena are explained by the steric constraints on molecular interactions in confinement. Our study is the first to explore recognition in DNA nanostructures with atomic force microscopy and lays out new tools to further quantify the effect of nanoconfinement on molecular interactions.


Assuntos
Nanoporos , Microscopia de Força Atômica , Espaços Confinados , DNA/química , Nanotecnologia/métodos
7.
Small ; 19(35): e2300900, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-37096928

RESUMO

Nanochannel-based confinement effect is a fascinating signal transduction strategy for high-performance sensing, but only size confinement is focused on while other confinement effects are unexplored. Here, a highly integrated nanochannel-electrodes chip (INEC) is created and a size/volume-dual-confinement enzyme catalysis model for rapid and sensitive bacteria detection is developed. The INEC, by directly sandwiching a nanochannel chip (60 µm in thickness) in nanoporous gold layers, creates a micro-droplet-based confinement electrochemical cell (CEC). The size confinement of nanochannel promotes the urease catalysis efficiency to generate more ions, while the volume confinement of CEC significantly enriches ions by restricting diffusion. As a result, the INEC-based dual-confinement effects benefit a synergetic enhancement of the catalytic signal. A 11-times ion-strength-based impedance response is obtained within just 1 min when compared to the relevant open system. Combining this novel nanoconfinement effects with nanofiltration of INEC, a separation/signal amplification-integrated sensing strategy is further developed for Salmonella typhimurium detection. The biosensor realizes facile, rapid (<20 min), and specific signal readout with a detection limit of 9 CFU mL-1 in culturing solution, superior to most reports. This work may create a new paradigm for studying nanoconfined processes and contribute a new signal transduction technique for trace analysis application.


Assuntos
Técnicas Biossensoriais , Espaços Confinados , Impedância Elétrica , Eletrodos , Salmonella , Catálise , Técnicas Biossensoriais/métodos , Técnicas Eletroquímicas
8.
Environ Sci Pollut Res Int ; 30(15): 44067-44085, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36680724

RESUMO

Effects of indoor temperature (T∞) and relative humidity (RH∞) on the airborne transmission of sneeze droplets in a confined space were studied over the T∞ range of 15-30 °C and RH∞ of 22-62%. In addition, a theoretical evaporation model was used to estimate the droplet lifetime based on experimental data. The results showed that the body mass index (BMI) of the participants played an important role in the sneezing jet velocity, while the impact of the BMI and gender of participants was insignificant on the size distribution of droplets. At a critical relative humidity RH∞,crit of 46%, the sneezing jet velocity and droplet lifetime were roughly independent of T∞. At RH∞ < RH∞,crit, the sneezing jet velocity decreased by increasing T∞ from 15 to 30 °C, while its trend was reversed at RH∞ > RH∞,crit. The maximum spreading distance of aerosols increased by decreasing the RH∞ and increasing T∞, while the droplet lifetime increased by decreasing T∞ at RH∞ > RH∞,crit. The mean diameter of aerosolized droplets was less affected by T∞ than the large droplets at RH∞ < RH∞,crit, while the mean diameter and number fraction of aerosols were more influenced by RH∞ than the T∞ in the range of 46% ≤ RH∞ ≤ 62%. In summary, this study suggests suitable indoor environmental conditions by considering the transmission rate and lifetime of respiratory droplets to reduce the spread of COVID-19.


Assuntos
COVID-19 , Humanos , Aerossóis e Gotículas Respiratórios , Espaços Confinados , Espirro , Tamanho da Partícula
9.
Chinese Critical Care Medicine ; (12): 777-781, 2023.
Artigo em Chinês | WPRIM (Pacífico Ocidental) | ID: wpr-982674

RESUMO

Major natural disasters seriously threaten human life and health. After earthquakes and other catastrophes, survivors are often trapped in the confined spaces caused by the collapse of ground and buildings, with relative separation from the outside world, restricted access, complex environment, and oncoming or ongoing unsafety, leading to the rescue extremely difficult. In order to save lives and improve the outcome more efficiently in the confined spaces after natural disasters, it is very important to standardize and reasonably apply the trauma assessment and first aid workflow. This study focuses on trauma assessment and first aid. From the aspects of trauma assessment, vital signs stabilization, hemostasis and bandaging, post-trauma anti-infection, and the transportation of patients, a trauma first aid work process suitable for a small space of a major natural disaster is formed, It is helpful to realize the immediate and efficient treatment of trauma in the confined spaces after natural catastrophes, to reduce the rate of death and disability and improve the outcome of patients.


Assuntos
Humanos , Desastres , Primeiros Socorros , Espaços Confinados , Terremotos
10.
Chem Commun (Camb) ; 58(100): 13873-13886, 2022 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-36448362

RESUMO

Metal-organic cages (MOCs) have become an intensely studied class of abiotic host molecules. This is due to the ability to generate a myriad of polyhedral architectures from relatively simple, and minimal numbers of, components in high yield and under thermodynamic control. The encapsulation of molecular guests within the nanoscale, confined cavities of these cages frequently draws comparisons with enzymatic binding sites. In this regard, the ostensible ease with which chemical modifications can be made to these internal cavities adds to their attractiveness, as they can be readily tailored with a high degree of precision. In this Feature Article, the ways in which the cavities of MOCs can be engineered at the molecular level will be looked at. The discussion will be divided across three key parameters: size, shape and functionality. Most concepts will be exemplified with a focus on the Pd2L4 class of assemblies due to their relative structural simplicity and the wealth of studies reported in the literature. The core principles discussed will, however, be generalisable to other classes of MOCs, and abiotic host systems as a whole. Gaining increasing mastery over the fine tuning of MOC cavity properties, whilst retaining facile, high-fidelity self-assembly processes, will lead to ever more precise engineering of the cavities of artificial host systems with complex and highly specific functionality.


Assuntos
Espaços Confinados , Engenharia , Metais
11.
Nat Commun ; 13(1): 6289, 2022 10 21.
Artigo em Inglês | MEDLINE | ID: mdl-36271078

RESUMO

Biological microorganisms overcome the Brownian motion at low Reynolds numbers by utilizing symmetry-breaking mechanisms. Inspired by them, various microrobot locomotion methods have been developed at the microscale by breaking the hydrodynamic symmetry. Although the boundary effects have been extensively studied for microswimmers and employed for surface-rolling microrobots, the behavior of microrobots in the proximity of multiple wall-based "confinement" is yet to be elucidated. Here, we study the confinement effect on the motion of surface-rolling microrobots. Our experiments demonstrate that the locomotion efficiency of spherical microrollers drastically decreases in confined spaces due to out-of-plane rotational flows generated during locomotion. Hence, a slender microroller design, generating smaller rotational flows, is shown to outperform spherical microrollers in confined spaces. Our results elucidate the underlying physics of surface rolling-based locomotion in confined spaces and present a design strategy with optimal flow generation for efficient propulsion in such areas, including blood vessels and microchannels.


Assuntos
Robótica , Robótica/métodos , Espaços Confinados , Movimento (Física) , Locomoção , Hidrodinâmica
12.
J Wildl Dis ; 58(4): 735-745, 2022 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-36228618

RESUMO

Boma adaptation is an important component of rhinoceros translocations to allow transition to new diets, restricted space, and quarantine for disease screening. However, up to 20% of recently captured white rhinoceros (Ceratotherium simum) do not adjust to captivity, resulting in early release or even death. The causes and physiologic consequences of maladaptation to boma confinement are poorly understood. The aim of this investigation was to evaluate hematologic and serum biochemical changes in maladapted rhinoceros compared to animals that adapted under the same boma conditions. Ninety-six white rhinoceros were captured between 2009 and 2011 in Kruger National Park, South Africa and placed in bomas prior to translocation. Weight, complete blood count, and serum biochemical panel results were recorded when rhinoceros were placed in the boma and repeated on the day of release. In this study, the mean duration of boma confinement for maladapted white rhinoceros was 13 d (range 8-16 d) compared to 89.9 d (range 39-187 d) for adapted animals. Mean weight loss between capture and release was significantly greater in maladapted rhinoceros (224.0 versus 65.9 kgs; P<0.001). Although adapted rhinoceros had statistically significant changes in some hematologic and biochemical values, most were not considered clinically relevant. In contrast, the maladapted rhinoceros had significant changes at the time of early release from the boma, including evidence of leukocytosis with left shift, lymphopenia, eosinopenia, decreased red blood cell count and hematocrit, increased serum creatine kinase, and decreased serum calcium, phosphorus, and magnesium values. Along with loss of body condition, these findings were consistent with a stress-associated catabolic response. These changes occurred in the first 2 wk of confinement, and the results provide a foundation for evaluating adaptation in white rhinoceros. Future studies should focus on factors that improve adaptation and welfare of recently confined free-ranging white rhinoceros.


Assuntos
Adaptação Psicológica , Espaços Confinados , Perissodáctilos , Animais , Parques Recreativos , África do Sul/epidemiologia , Bem-Estar do Animal , Estresse Fisiológico
13.
Artigo em Chinês | MEDLINE | ID: mdl-36052593

RESUMO

Hydrogen sulphide poisoning is an acute poisoning event that occurs frequently in summer. A case of acute hydrogen sulphide poisoning in a confined space in August 2018 was investigated and clinical data were analyzed. This is a typical case of acute hydrogen sulfide gas poisoning in a confined space. The main cause of the accident is the lack of occupational protection and illegal rescue. Among the 5 patients, 3 died, 1 patient had long-term sequelae of nervous system damage such as cortical blindness, and 1 patient was cured.


Assuntos
Intoxicação por Gás , Sulfeto de Hidrogênio , Intoxicação , Acidentes , Acidentes de Trabalho , Espaços Confinados , Humanos
14.
Behav Processes ; 201: 104712, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35905925

RESUMO

Many cats show signs of fear and stress during veterinary examinations and procedures, with environmental stimuli such as noise contributing to these responses. The objective of this study was to investigate the effect of background noise commonly heard in veterinary clinics (people talking, kennel doors shutting, dogs barking) on behavioural and physiological responses in companion cats. In Experiment 1, owned cats underwent a mock physical examination in a veterinary clinic with (n = 16) or without (n = 16) a pre-recorded noise track. A second experiment was conducted to assess cat responses to noise outside of handling and a clinic environment. In Experiment 2, shelter cats were either exposed (n = 15) or not exposed (n = 15) to the same noise track while allowed free movement in a small enclosure. Physiological and behavioural responses previously validated as negative responses in cats (e.g., indicative of fear, stress and aversion) were recorded, and outcome variables were compared between treatments. For both experiments, cats exposed to the noise track showed higher heart and respiratory rates. Noise was not associated with behavioural changes during the physical examination; however, cats who were freely moving showed more behavioural signs of fear and/or stress during noise exposure compared to the no noise conditions. These results show that high levels of background noise elicit physiological stress responses in cats, while ceiling effects of the examination and exposure to the clinic environment likely prevented treatment-related behavioral differences from being detected during the physical examination. It is recommended that those working with cats in environments with high levels of background noise limit cat exposure to these noises to reduce cat fear and stress.


Assuntos
Comportamento Animal , Espaços Confinados , Animais , Comportamento Animal/fisiologia , Gatos , Cães , Medo , Hospitais Veterinários , Humanos , Animais de Estimação
15.
Artigo em Inglês | MEDLINE | ID: mdl-35742666

RESUMO

Employee performance in terms of knowledge of job scope, safe working practices, and safety-related attitude at work are used to measure an organization's success in managing employee welfare and safety to prevent workplace injury and death. This study aims to determine the level of knowledge, attitude, and practice on safe working in confined space among water services workers. A cross-sectional study involving a randomly selected 207 water services workers working in a confined space was performed in the central region of Malaysia. The assessment was performed using a validated Malay self-administered questionnaire. Descriptive statistics, Chi-square test and Logistic regression were used for data analyses. The study's participants were all men, with a mean (SD) age of 35.2 (8.83) years. The average working duration was 10.8 years. Overall, 67.1% of participants had good knowledge, while 65.7% had a positive attitude. The majority of the workers (60.4%) were found to follow safe working practices. Regression analysis revealed that significant predictors for knowledge were age [Adjusted odds ratio (Adj. OR) 2.793; 95% CI: 1.310, 5.955; p = 0.008] and attitude (Adj. OR 2.127; 95% CI: 1.011, 4.526; p = 0.048). Attitude was influenced by marital status (Adj. OR 4.126; 95% CI: 2.079, 8.186; p < 0.001) and knowledge level (Adj. OR 2.224; 95% CI: 1.025, 4.824; p = 0.043). A positive attitude was the sole predictor influencing the safe practice (Adj. OR; 1.878; 95% CI: 1.041, 3.388; p = 0.036). In conclusion, the workers' levels of knowledge, attitudes, and practices were relatively satisfactory. Extensive investment in workplace safety and health programs, appropriate training, growth opportunities, and effective employee performance evaluation methodologies may assist workers in performing at their best.


Assuntos
Espaços Confinados , Conhecimentos, Atitudes e Prática em Saúde , Adulto , Estudos Transversais , Humanos , Malásia , Masculino , Inquéritos e Questionários , Água
16.
Cell Syst ; 13(7): 514-529.e10, 2022 07 20.
Artigo em Inglês | MEDLINE | ID: mdl-35679858

RESUMO

Navigation through a dense, physically confining extracellular matrix is common in invasive cell spread and tissue reorganization but is still poorly understood. Here, we show that this migration is mediated by cyclic changes in the activity of a small GTPase RhoA, which is dependent on the oscillatory changes in the activity and abundance of the RhoA guanine nucleotide exchange factor, GEF-H1, and triggered by a persistent increase in the intracellular Ca2+ levels. We show that the molecular clock driving these cyclic changes is mediated by two coupled negative feedback loops, dependent on the microtubule dynamics, with a frequency that can be experimentally modulated based on a predictive mathematical model. We further demonstrate that an increasing frequency of the clock translates into a faster cell migration within physically confining spaces. This work lays the foundation for a better understanding of the molecular mechanisms dynamically driving cell migration in complex environments.


Assuntos
Espaços Confinados , Microtúbulos , Movimento Celular/genética , Fatores de Troca de Nucleotídeo Guanina Rho
17.
Biophys J ; 121(13): 2653-2662, 2022 07 05.
Artigo em Inglês | MEDLINE | ID: mdl-35398019

RESUMO

Symbiotic bacteria often navigate complex environments before colonizing privileged sites in their host organism. Chemical gradients are known to facilitate directional taxis of these bacteria, guiding them toward their eventual destination. However, less is known about the role of physical features in shaping the path the bacteria take and defining how they traverse a given space. The flagellated marine bacterium Vibrio fischeri, which forms a binary symbiosis with the Hawaiian bobtail squid, Euprymna scolopes, must navigate tight physical confinement during colonization, squeezing through a tissue bottleneck constricting to ∼2 µm in width on the way to its eventual home. Using microfluidic in vitro experiments, we discovered that V. fischeri cells alter their behavior upon entry into confined space, straightening their swimming paths and promoting escape from confinement. Using a computational model, we attributed this escape response to two factors: reduced directional fluctuation and a refractory period between reversals. Additional experiments in asymmetric capillary tubes confirmed that V. fischeri quickly escape from confined ends, even when drawn into the ends by chemoattraction. This avoidance was apparent down to a limit of confinement approaching the diameter of the cell itself, resulting in a balance between chemoattraction and evasion of physical confinement. Our findings demonstrate that nontrivial distributions of swimming bacteria can emerge from simple physical gradients in the level of confinement. Tight spaces may serve as an additional, crucial cue for bacteria while they navigate complex environments to enter specific habitats.


Assuntos
Espaços Confinados , Natação , Aliivibrio fischeri/fisiologia , Animais , Decapodiformes/microbiologia , Decapodiformes/fisiologia , Simbiose/fisiologia
18.
Artigo em Inglês | MEDLINE | ID: mdl-35162265

RESUMO

Confined space workers do a wide range of tasks, many of which have a significant risk of hazardous exposure. Hence, a reliable and valid questionnaire is important in assessing the knowledge, attitude, and practice (KAP) of workers in this field. The present study was conducted to develop and validate a questionnaire that could assess the KAP for safe working in a confined space. The questionnaire went through a development and validation process. The development stage consisted of a literature review, expert's opinion, and evaluation by experts in the field via cognitive debriefing. The validation stage encompassed exploratory and confirmatory parts to investigate the psychometric properties of the questionnaire. A total of 350 participants were recruited among confined space workers from two oil and gas companies in Malaysia. The two-parameter logistic item response theory (2-PL IRT) analysis was used for the knowledge section. Exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) were used in the attitude and practice sections of the validation stage. The development stage resulted in 30 items for knowledge, attitude, and practice sections. Items in the knowledge section showed an acceptable difficulty and discrimination, as noted during the 2-PL IRT analysis. The EFA resulted in a one-factor model for attitude and practice sections, and contained 18 items, with factor loading > 0.4. The Cronbach's alpha was 0.804 and 0.917 for attitude and practice sections, respectively. The CFA for attitude and practice sections indicated a good model fitness (Raykov's rho = 0.814 and 0.912, respectively). All items indicated good reliability and valid psychometrics for determining KAP on safe working in a confined space.


Assuntos
Espaços Confinados , Conhecimentos, Atitudes e Prática em Saúde , Humanos , Psicometria/métodos , Reprodutibilidade dos Testes , Inquéritos e Questionários
19.
Microbiome ; 10(1): 26, 2022 02 07.
Artigo em Inglês | MEDLINE | ID: mdl-35125119

RESUMO

A human spaceflight to Mars is scheduled for the next decade. In preparation for this unmatched endeavor, a plethora of challenges must be faced prior to the actual journey to Mars. Mission success will depend on the health of its crew and its working capacity. Hence, the journey to Mars will also depend on the microbiome and its far-reaching effects on individual crew health, the spaceship's integrity, and food supply. As human beings rely on their microbiome, these microbes are essential and should be managed to ensure their beneficial effects outweigh potential risks. In this commentary, we focus on the current state of knowledge regarding a healthy (gut) microbiome of space travelers based on research from the International Space Station and simulation experiments on Earth. We further indicate essential knowledge gaps of microbial conditions during long-term space missions in isolated confined space habitats or outposts and give detailed recommendations for microbial monitoring during pre-flight, in-flight, and post-flight. Finally, the conclusion outlines open questions and aspects of space traveler's health beyond the scope of this commentary. Video Abstract.


Assuntos
Marte , Microbiota , Voo Espacial , Astronautas , Espaços Confinados , Humanos , Astronave
20.
Int J Mol Sci ; 23(4)2022 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-35216456

RESUMO

Sulfur-containing groups preorganized on macrocyclic scaffolds are well suited for liquid-phase complexation of soft metal ions; however, their binding potential was not extensively studied at the air-water interface, and the effect of thioether topology on metal ion binding mechanisms under various conditions was not considered. Herein, we report the interface receptor characteristics of topologically varied thiacalixarene thioethers (linear bis-(methylthio)ethoxy derivative L2, O2S2-thiacrown-ether L3, and O2S2-bridged thiacalixtube L4). The study was conducted in bulk liquid phase and Langmuir monolayers. For all compounds, the highest liquid-phase extraction selectivity was revealed for Ag+ and Hg2+ ions vs. other soft metal ions. In thioether L2 and thiacalixtube L4, metal ion binding was evidenced by a blue shift of the band at 303 nm (for Ag+ species) and the appearance of ligand-to-metal charge transfer bands at 330-340 nm (for Hg2+ species). Theoretical calculations for thioether L2 and its Ag and Hg complexes are consistent with experimental data of UV/Vis, nuclear magnetic resonance (NMR) spectroscopy, and single-crystal X-ray diffractometry of Ag-thioether L2 complexes and Hg-thiacalixtube L4 complex for the case of coordination around the metal center involving two alkyl sulfide groups (Hg2+) or sulfur atoms on the lower rim and bridging unit (Ag+). In thiacrown L3, Ag and Hg binding by alkyl sulfide groups was suggested from changes in NMR spectra upon the addition of corresponding salts. In spite of the low ability of the thioethers to form stable Langmuir monolayers on deionized water, one might argue that the monolayers significantly expand in the presence of Hg salts in the water subphase. Hg2+ ion uptake by the Langmuir-Blodgett (LB) films of ligand L3 was proved by X-ray photoelectron spectroscopy (XPS). Together, these results demonstrate the potential of sulfide groups on the calixarene platform as receptor unit towards Hg2+ ions, which could be useful in the development of Hg2+-selective water purification systems or thin-film sensor devices.


Assuntos
Espaços Confinados , Mercúrio , Ligantes , Mercúrio/química , Metais/química , Sais , Sulfetos/química , Enxofre , Água/química
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...