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Molecules (Basel, Switzerland) Mar 2021Surface bubbles are present in many industrial processes and in nature, as well as in carbonated beverages. They have motivated many theoretical, numerical and... (Review)
Review
Surface bubbles are present in many industrial processes and in nature, as well as in carbonated beverages. They have motivated many theoretical, numerical and experimental works. This paper presents the current knowledge on the physics of surface bubbles lifetime and shows the diversity of mechanisms at play that depend on the properties of the bath, the interfaces and the ambient air. In particular, we explore the role of drainage and evaporation on film thinning. We highlight the existence of two different scenarios depending on whether the cap film ruptures at large or small thickness compared to the thickness at which van der Waals interaction come in to play.
Topics: Air; Microbubbles; Surface Properties; Water
PubMed: 33804584
DOI: 10.3390/molecules26051317 -
Journal of Oleo Science Jun 2020The surface charge/surface potential of the air/water interface plays a key role in many natural and industrial processes. Since the first decade of the 20 century,... (Review)
Review
The surface charge/surface potential of the air/water interface plays a key role in many natural and industrial processes. Since the first decade of the 20 century, there are many theoretical proposals to describe the surface charge in the presence of different moieties. However, a complete and consistent description of the interfacial layer remains elusive. More recently, the theoretical frameworks and experimental data get complementary support from the simulation at a molecular level. This paper reviews the recent developments from the theoretical, experimental and simulation aspects. The combined results indicated that the interaction between hydration shells of adsorbed ions and the H-bonds network of surface water plays a critical role in the ionic adsorption. The factor should be incorporated into the conventional theories to correctly predict the ion distribution near the air/water surface.
Topics: Adsorption; Air; Hydrogen Bonding; Ions; Surface Properties; Water
PubMed: 32404551
DOI: 10.5650/jos.ess20024 -
The Science of the Total Environment Jun 2022Many polychlorinated biphenyl (PCB) congeners are found in both legacy Aroclor mixtures and modern materials, and both contribute to PCBs levels in ambient air. The...
Many polychlorinated biphenyl (PCB) congeners are found in both legacy Aroclor mixtures and modern materials, and both contribute to PCBs levels in ambient air. The various sources of PCBs make it difficult to quantify the relative importance of emissions from remaining legacy materials and emissions of PCBs released from production and use of modern products. To address this challenge, we utilized active and passive sampling, analytical methods optimized for PCBs, and Positive Matrix Factorization (PMF) and cos theta to examine the chemical signature of PCBs in Chicago air. Here we report our findings for over 640 samples collected over 7 years and analyzed for all 209 congeners. We conclude that Aroclor sources (1254, 1016/1242, and 1260) are consistent and dominant contributors to Chicago air. However, non-Aroclors sources accounted for 13%-16% of the total PCBs measured. Our analysis indicates non-Aroclor sources explain 99% of PCB11, 90% of PCB 68, and 58-69% of congeners with 8 to 10 chlorines in Chicago air. All of these are known to be emitted from paints or silicone polymers. Additionally, we identified over 20 congeners that have non-Aroclor contributions of more than 50% including PCB 3 (4-monochlorobiphenyl, 83% non-Aroclor) as well as 7 congeners of unknown sources: PCBs 43, 46, 55, 89, 96, 137, and 139 + 140. Non-Aroclor emission sources contribute to the entire range of congeners from mono- to deca-chlorobiphenyls. We found evidence of highly localized non-Aroclor sources including a signature similar to that of green paint. We also found source signals similar to the PCB congeners volatilizing from and absorbing to neighboring Lake Michigan. The measured profiles vary from season to season: lower chlorinated congeners dominate in winter months while higher chlorinated congeners contribute more in summer.
Topics: Air; Aroclors; Chicago; Lakes; Polychlorinated Biphenyls
PubMed: 35066038
DOI: 10.1016/j.scitotenv.2022.153263 -
Applied and Environmental Microbiology Jan 2016Airborne dispersal of microalgae has largely been a blind spot in environmental biological studies because of their low concentration in the atmosphere and the technical... (Review)
Review
Airborne dispersal of microalgae has largely been a blind spot in environmental biological studies because of their low concentration in the atmosphere and the technical limitations in investigating microalgae from air samples. Recent studies show that airborne microalgae can survive air transportation and interact with the environment, possibly influencing their deposition rates. This minireview presents a summary of these studies and traces the possible route, step by step, from established ecosystems to new habitats through air transportation over a variety of geographic scales. Emission, transportation, deposition, and adaptation to atmospheric stress are discussed, as well as the consequences of their dispersal on health and the environment and state-of-the-art techniques to detect and model airborne microalga dispersal. More-detailed studies on the microalga atmospheric cycle, including, for instance, ice nucleation activity and transport simulations, are crucial for improving our understanding of microalga ecology, identifying microalga interactions with the environment, and preventing unwanted contamination events or invasions.
Topics: Air; Air Pollutants; Ecosystem; Environmental Monitoring; Microalgae
PubMed: 26801574
DOI: 10.1128/AEM.03333-15 -
Journal of Negative Results in... Sep 2013From a mechanistic or physical perspective there is no basis to suspect that electric charges on clusters of air molecules (air ions) would have beneficial or... (Review)
Review
BACKGROUND
From a mechanistic or physical perspective there is no basis to suspect that electric charges on clusters of air molecules (air ions) would have beneficial or deleterious effects on respiratory function. Yet, there is a large lay and scientific literature spanning 80 years that asserts exposure to air ions affects the respiratory system and has other biological effects.
AIMS
This review evaluates the scientific evidence in published human experimental studies regarding the effects of exposure to air ions on respiratory performance and symptoms.
METHODS
We identified 23 studies (published 1933-1993) that met our inclusion criteria. Relevant data pertaining to study population characteristics, study design, experimental methods, statistical techniques, and study results were assessed. Where relevant, random effects meta-analysis models were utilized to quantify similar exposure and outcome groupings.
RESULTS
The included studies examined the therapeutic benefits of exposure to negative air ions on respiratory outcomes, such as ventilatory function and asthmatic symptoms. Study specific sample sizes ranged between 7 and 23, and studies varied considerably by subject characteristics (e.g., infants with asthma, adults with emphysema), experimental method, outcomes measured (e.g., subjective symptoms, sensitivity, clinical pulmonary function), analytical design, and statistical reporting.
CONCLUSIONS
Despite numerous experimental and analytical differences across studies, the literature does not clearly support a beneficial role in exposure to negative air ions and respiratory function or asthmatic symptom alleviation. Further, collectively, the human experimental studies do not indicate a significant detrimental effect of exposure to positive air ions on respiratory measures. Exposure to negative or positive air ions does not appear to play an appreciable role in respiratory function.
Topics: Air; Humans; Ions; Peak Expiratory Flow Rate; Respiration
PubMed: 24016271
DOI: 10.1186/1477-5751-12-14 -
Cell and Tissue Research Jan 2021Extant anuran amphibians originate from an evolutionary intersection eventually leading to fully terrestrial tetrapods. In many ways, they have to deal with exposure to... (Review)
Review
Extant anuran amphibians originate from an evolutionary intersection eventually leading to fully terrestrial tetrapods. In many ways, they have to deal with exposure to both terrestrial and aquatic environments: (i) phylogenetically, as derivatives of the first tetrapod group that conquered the terrestrial environment in evolution; (ii) ontogenetically, with a development that includes aquatic and terrestrial stages connected via metamorphic remodeling; and (iii) individually, with common changes in habitat during the life cycle. Our knowledge about the structural organization and function of the amphibian olfactory system and its relevance still lags behind findings on mammals. It is a formidable challenge to reveal underlying general principles of circuity-related, cellular, and molecular properties that are beneficial for an optimized sense of smell in water and air. Recent findings in structural organization coupled with behavioral observations could help to understand the importance of the sense of smell in this evolutionarily important animal group. We describe the structure of the peripheral olfactory organ, the olfactory bulb, and higher olfactory centers on a tissue, cellular, and molecular levels. Differences and similarities between the olfactory systems of anurans and other vertebrates are reviewed. Special emphasis lies on adaptations that are connected to the distinct demands of olfaction in water and air environment. These particular adaptations are discussed in light of evolutionary trends, ontogenetic development, and ecological demands.
Topics: Air; Amphibians; Animals; Receptors, Odorant; Water
PubMed: 33496878
DOI: 10.1007/s00441-020-03377-5 -
Parasitology Jun 2020Free-living amoebae (FLA) are widely dispersed in the environment, can cause opportunistic and non-opportunistic infections in humans and other animals. The aim of the...
Free-living amoebae (FLA) are widely dispersed in the environment, can cause opportunistic and non-opportunistic infections in humans and other animals. The aim of the present study was characterize FLA obtained from air-conditioners of a public hospital in the city of Florianópolis, SC, Brazil. Fifty-four dust samples were collected of air conditioners, and were inoculated on 1.5% non-nutrient agar, overlaid with layers of Escherichia coli. Subsequently the isolates were axenised in PYG growth medium. The morphological and molecular characterization of the isolates was performed, as well as the tolerance (physiological) assays were used to evaluate the pathogenic potential. The results revealed the presence of FLA in 42 (77.8%) of the collected samples. Of these, 39 (92.9%) axenic isolates of FLA were obtained for morphological and genotypic studies. All the isolates characterized belong to the genus Acanthamoeba. Nineteen (48.7%) isolates belong to the genotype T4, 16 (41.0%) to the T5 genotype and 4 (10.3%) to genotype T11. Seven (18.0%) isolates were considered potentially pathogenic in tolerance assays. These findings require attention, considering the isolation environment and immunocompromised characteristics of many hospitalized patients.
Topics: Acanthamoeba; Air; Air Conditioning; Air Pollution; Brazil; Genotype; Hospitals
PubMed: 32183918
DOI: 10.1017/S0031182020000487 -
Medical Gas Research 2023The noble gas argon has demonstrated biological activity that may prove useful as a medical intervention. Pharmacokinetics, the disposition of the drug molecule in the...
The noble gas argon has demonstrated biological activity that may prove useful as a medical intervention. Pharmacokinetics, the disposition of the drug molecule in the body through time, is fundamental necessary knowledge to drug discovery, development and even post-marketing. The fundamental measurement in pharmacokinetic studies is blood concentration of the molecule (and its metabolites) of interest. While a physiologically based model of argon pharmacokinetics has appeared in the literature, no experimental data have been published. Thus, argon pharmaceutical development requires measurement of argon solubility in blood. This paper reports on the development of a technique based on mass spectrometry for measuring argon solubility in liquids, including blood, to be further employed in pharmacokinetics testing of argon. Based on a prototype, results are reported from sensitivity experiments using ambient air, water and rabbit blood. The key takeaway is that the system was sensitive to argon during all of the testing. We believe the technique and prototype of the quadrupole mass spectrometer gas analyzer will be capable of inferring argon pharmacokinetics through the analysis of blood samples.
Topics: Animals; Rabbits; Argon; Solubility; Mass Spectrometry; Air; Water
PubMed: 37077120
DOI: 10.4103/2045-9912.351106 -
Sensors (Basel, Switzerland) Jan 2023Absolute measurement of radiant power in the X-ray region is essential for many applications in astrophysics, spectroscopy, and X-ray diagnostics. Comparison between...
Absolute measurement of radiant power in the X-ray region is essential for many applications in astrophysics, spectroscopy, and X-ray diagnostics. Comparison between different measuring methods is an effective way to check their reliability. In the present work, a comparison of X-ray radiant power absolute measurement between a free-air ionization chamber and a cryogenic electrical substitution radiometer was performed at Beijing Synchrotron Radiation Facility. The absolute radiant power obtained by these two methods were mutually compared via a transfer standard detector's spectral responsivity at a photon energy of 10 keV. The result of the comparison showed that the difference was 0.47%. A conclusion was reached that the free-air ionization chamber and the cryogenic electrical substitution radiometer agreed within the combined relative uncertainty of 3.35%.
Topics: X-Rays; Air Ionization; Reproducibility of Results; Radiometry; Radiography
PubMed: 36679803
DOI: 10.3390/s23021006 -
The Journal of Hospital Infection Sep 2019
Topics: Air Microbiology; Air Movements; Humans; Infection Control; Ventilation
PubMed: 30978370
DOI: 10.1016/j.jhin.2019.04.003