Cloud Chamber Research Articles

Vertical Distribution of Atmospheric Ice Nucleating Particles in Winter over Northwest China Based on Aircraft Observations

The concentration of ice nucleating particles (INPs) in the cloud layer affects cloud processes more importantly than at the ground level. To make up for deficiencies in the observation of the vertical distribution of INPs over different background regions of China, airborne sampling of INPs was carried out at the altitudes of 2000–5500 m over Turpan, Xinjiang, northwest China on 29 December 2019, and the samples were analyzed in a static vacuum water vapor diffusion chamber. The sources and relationships of the INPs with meteorological conditions and the variation of the concentrations of aerosol particles of different sizes were explored. The results indicate that the concentration of INPs varies from 0.25 to 15.7 L−1 when the nucleation temperature changes from −17 to −26 °C and the relative humidity with respect to water (RHw) varies from 95 to 105%. The existence of an inversion layer near the planetary boundary layer (PBL) inhibits the vertical transport of aerosols, thus affecting the vertical distribution of INP concentration. INPs in the free atmosphere mainly originate from fine-mode aerosol particles transported from long distances by westerly winds and do not change significantly with height. The air mass in the PBL is short-range transported, and the INP concentration reaches 15.7 L−1 at T =−26 °C and RHw = 105%, which is obviously higher than that above the PBL. The analyses provide evidence that the meteorological conditions played an important part in regulating the vertical distribution of INPs.

Evidence for Anthropogenic Organic Aerosols Contributing to Ice Nucleation

AbstractThe role of organic aerosols (OA) as ice nucleating particles (INPs) deserves attention because of their high atmospheric abundance. The low concentration of INPs poses challenges in identifying the ice nucleation (IN) of OA among a mix of aerosol types in ambient environment. This study coupled a catalytic stripper system (350°C heating) with a continuous flow diffusion chamber to online investigate the immersion INPs of ambient particles at −30°C at a suburban site. Significant reduction (71 ± 25%) of INP concentrations after evaporation suggested that INPs can be significantly contributed by volatile OA. In addition, nonvolatile OA were more efficient INPs than black carbon. Oxygenated OA by photooxidation and lower ambient promoted the IN activity at noon, when the OA may be more viscous. These results hereby present the first field evidence that OA in anthropogenically influenced regions can be efficient INPs well above the homogeneous IN temperature.

Measuring Atmospheric Radon Levels Using a Cloud Chamber

The Wilson cloud chamber, invented in 1911 by Scottish physicist Charles Wilson, is a remarkably simple and effective charged particle detector. Cloud chambers were used regularly in particle physics experiments for decades, until being supplanted by bubble chambers. In this article, we describe a lab activity that is suitable for introductory-level physics students using a cloud chamber to measure the rate of alpha decay in the atmosphere. In performing this experiment, the students deepen their understanding of alpha decay, including the random nature of the process. They also become acquainted with statistical uncertainties from measuring a random process.

Extensive air shower tracker using Cherenkov detection

Cosmic rays continuously bombard Earth’s atmosphere triggering cascades of secondary particles. Many constituents progress to reach the surface and capturing these events can intrigue and awe young curious minds, opening them to the amazing world of physics. Cloud chambers are an established method of revealing the subatomic world; frequently used by universities to introduce cosmic rays to visitors and prospective students, they provide a fascinating real-time display of the ‘ghostly’ particles showering upon those viewing.Using the Cherenkov radiation detection technique, we have developed a novel, compact, Extensive Air Shower (EAS) particle tracking method that enhances the cloud chamber visualisation of cosmic ray interactions towards a digital audience. Once digital, live event interaction can be streamed to multiple display devices presenting an immediate illustration of the event that showered in that location.Our instrument hardware is built around Cherenkov-optimised silicon photomultiplier sensors. Each single detection unit monitors particle event rate and tracks incident angle by measuring Cherenkov intensity. By operating multiple detection units in one location, we can record time correlated air shower events to monitor and collate information on the primary cosmic rays.We introduce first results, illustrating instrument response and EAS rate variations, compiled from the initial running period of our development instruments. We present intensity spectra, compare with simulation, and describe the instrument response due to sensor location, Cherenkov intensity, mean muon energy and detector acceptance angle.With further development towards low-cost readout electronics, we aim to build a networked array of trackers, located around the campus, to expand data gathering ability and scientific potential.

Study of a calibration system for soil respiration measurement chambers

Purpose. Soil respiration measurement is an important component of the global carbon cycle assessment. To effectively validate the measurement performance of the monitoring instruments and provide accurate carbon flux data, a new flux-monitoring gas-chamber calibration system was investigated. Method. In an environmentally controlled laboratory, a concentration calculation calibration system, mass calculation calibration system, and flow calculation calibration system were used to quantify soil CO2 emissions. The measurement performance of the soil-respiration monitoring gas chamber was investigated, and the strengths and weaknesses of each calibration system were examined. Results. The unsteady-state flow chamber and steady-state chamber measurements had fewer errors and provided better results than the unsteady-state nonflow chamber. The measured values of the closed chamber were low, whereas the measured values of the open chamber were occasionally high and low. For calibration systems, the concentration calculation system is easy to operate; however, the reference flux values are unstable, and the mass calculation system allows for different gas transport mechanisms. However, it is complex to operate and it is difficult to control the air pressure in the diffusion chamber. The calibration process of the flow calculation system was stable and easy to operate; however, the experimental time was long, and the CO2 gas consumption was high. However, for the calibration effect, the optimal calibration system was the flow-meter algorithm. Conclusion. This study proposes a better calibration method for the soil CO2 flux gas chamber, which is conducive to improving the measurement accuracy of the instrument, and provides new ideas for the calibration of other environmental gas monitoring instruments.

Dynamic pressure evolution during the LHC operation

For the accelerator community and the vacuum scientists, the understanding of the beam interactions with a vacuum chamber is fundamental to provide solutions to mitigate pressure rises induced by electron, photon, and ion molecular desorption. Moreover, beam instabilities induced by ion and electron clouds must be investigated in order to find solutions to reduce them. This study presents in situ measurements of pressure evolutions and electrical currents performed during the LHC RUN II (2018). The proton beam circulating in the LHC vacuum chamber ionizes the residual gas producing electrons as well as positive ions. These charged particles are accelerated away from the beam and reach the vacuum chamber wall, inducing, among other phenomena, stimulated desorption and secondary electron emission. Moreover, protons emit synchrotron radiations that also induce photodesorption and photoelectron production. Experimental measurements of the electrical signals recorded on copper electrodes were compared to calculations considering both the secondary electron yield of copper and the electron energy distribution. All measurements performed with the Vacuum Pilot Sector in the LHC ring show the importance of taking into account a large variety of phenomena in order to understand the pressure evolution in the LHC. Results show that the multipacting threshold, corresponding to an increase in the electron cloud density, strongly depends on the number of protons per bunch. Finally, the ion current was measured with a biased electrode lower than $\ensuremath{-}500\text{ }\text{ }\mathrm{V}$. It was much higher than expected, pointing its origin not only from simple beam-gas ionization but also from the ionization of the residual gas by the electron cloud.

Microencapsulation and in situ incubation methodology for the cultivation of marine bacteria.

Environmental microorganisms are important sources of biotechnology innovations; however, the discovery process is hampered by the inability to culture the overwhelming majority of microbes. To drive the discovery of new biotechnology products from previously unculturable microbes, several methods such as modification of media composition, incubation conditions, single-cell isolation, and in situ incubation, have been employed to improve microbial recovery from environmental samples. To improve microbial recovery, we examined the effect of microencapsulation followed by in situ incubation on the abundance, viability, and diversity of bacteria recovered from marine sediment. Bacteria from marine sediment samples were resuspended or encapsulated in agarose and half of each sample was directly plated on agar and the other half inserted into modified Slyde-A-Lyzer™ dialysis cassettes. The cassettes were incubated in their natural environment (in situ) for a week, after which they were retrieved, and the contents plated. Colony counts indicated that bacterial abundance increased during in situ incubation and that cell density was significantly higher in cassettes containing non-encapsulated sediment bacteria. Assessment of viability indicated that a higher proportion of cells in encapsulated samples were viable at the end of the incubation period, suggesting that agarose encapsulation promoted higher cell viability during in situ incubation. One hundred and 46 isolates were purified from the study (32–38 from each treatment) to assess the effect of the four treatments on cultivable bacterial diversity. In total, 58 operational taxonomic units (OTUs) were identified using a 99% 16S rRNA gene sequence identity threshold. The results indicated that encapsulation recovered greater bacterial diversity from the sediment than simple resuspension (41 vs. 31 OTUs, respectively). While the cultivable bacterial diversity decreased by 43%–48% after in situ incubation, difficult-to-culture (Verrucomicrobia) and obligate marine (Pseudoalteromonas) taxa were only recovered after in situ incubation. These results suggest that agarose encapsulation coupled with in situ incubation in commercially available, low-cost, diffusion chambers facilitates the cultivation and improved recovery of bacteria from marine sediments. This study provides another tool that microbiologists can use to access microbial dark matter for environmental, biotechnology bioprospecting.

Structural and Functional Analysis of Excised Skins and Human Reconstructed Epidermis with Confocal Raman Spectroscopy and in Microfluidic Diffusion Chambers.

Several ex vivo and in vitro skin models are available in the toolbox of dermatological and cosmetic research. Some of them are widely used in drug penetration testing. The excised skins show higher variability, while the in vitro skins provide more reproducible data. The aim of the current study was to compare the chemical composition of different skin models (excised rat skin, excised human skin and human-reconstructed epidermis) by measurement of ceramides, cholesterol, lactate, urea, protein and water at different depths of the tissues. The second goal was to compile a testing system, which includes a skin-on-a-chip diffusion setup and a confocal Raman spectroscopy for testing drug diffusion across the skin barrier and accumulation in the tissue models. A hydrophilic drug caffeine and the P-glycoprotein substrate quinidine were used in the study as topical cream formulations. The results indicate that although the transdermal diffusion of quinidine is lower, the skin accumulation was comparable for the two drugs. The various skin models showed different chemical compositions. The human skin was abundant in ceramides and cholesterol, while the reconstructed skin contained less water and more urea and protein. Based on these results, it can be concluded that skin-on-a-chip and confocal Raman microspectroscopy are suitable for testing drug penetration and distribution at different skin layers within an exposition window. Furthermore, obese human skin should be treated with caution for skin absorption testing due to its unbalanced composition.

IChip increases the success of cultivation of TBT-resistant and TBT-degrading bacteria from estuarine sediment

Standard methods of microbial cultivation only enable the isolation of a fraction of the total environmental bacteria. Numerous techniques have been developed to increase the success of isolation and cultivation in the laboratory, some of which derive from diffusion chambers. In a diffusion chamber, environmental bacteria in agar medium are put back in the environment to grow as close to their natural conditions as possible, only separated from the environment by semi-permeable membranes. In this study, the iChip, a device that possesses hundreds of mini diffusion chambers, was used to isolate tributyltin (TBT) resistant and degrading bacteria. IChip was shown to be efficient at increasing the number of cultivable bacteria compared to standard methods. TBT-resistant strains belonging to Oceanisphaera sp., Pseudomonas sp., Bacillus sp. and Shewanella sp. were identified from Liverpool Dock sediment. Among the isolates in the present study, only members of Pseudomonas sp. were able to use TBT as a sole carbon source. It is the first time that members of the genus Oceanisphaera have been shown to be TBT-resistant. Although iChip has been used in the search for molecules of biomedical interest here we demonstrate its promising application in bioremediation.

Consideration of the possibilities of applying machine learning methods for data analysis when promoting services to bank's clients

The object of the research is modern online services and machine learning libraries for predicting the probability of the bank client's consent to the provision of the proposed services. One of the most problematic areas is the high unpredictability of the result in the field of banking marketing using the most common technique of introducing new services for clients – the so-called cold calling. Therefore, the question of assessing the probability and predicting the behavior of a potential client when promoting new banking services and services using cold calling is particularly relevant. In the course of the study, libraries of machine learning methods and data analysis of the Python programming language were used. A program was developed to build a model for predicting the behavior of bank customers using data processing methods using gradient boosting, regularization of gradient boosting, random forest algorithm and recurrent neural networks. Analogous models were built using cloud machine learning services Azure ML, BigML and the Auto-sklearn library. Data analysis and prediction models built using Python language libraries have a fairly high quality – an average of 94.5 %. Using the Azure ML cloud service, a predictive model with an accuracy of 88.6 % was built. The BigML machine learning service made it possible to build a model with an accuracy of 88.8 %. Machine learning methods from the Auto-sklearn library made it possible to obtain a model with a higher quality – 94.9 %. This is due to the fact that the proposed libraries of the Python programming language allow better customization of data processing methods and machine learning to obtain more accurate models than free cloud services that do not provide such capabilities. Thanks to this, it is possible to obtain a predictive model of the behavior of bank customers with a fairly high degree of accuracy. It is worth noting that in order to make a prediction (forecast), it is necessary to study the context of the task, process the data, build various machine learning algorithms, evaluate the quality of the models and choose the best of them.

Pre‐Activation of Ice Nucleating Particles in Deposition Nucleation Mode: Evidence From Measurement Using a Static Vacuum Water Vapor Diffusion Chamber in Xinjiang, China

AbstractPre‐activation of ice nucleating particles (INPs) is a potential mechanism to enhance ice generation in mixed‐phase clouds, but evidence of INP pre‐activation is still limited. In this study, the pre‐activation of INPs in deposition mode is investigated using refreezing experiments in a static vacuum water vapor diffusion chamber with aerosols sampled in Xinjiang, China. The results indicate that the activation efficiency of INP was enhanced after pre‐activation. Statistically, the INP concentration increased by 266%, 112%, and 70% at −10°C, −14°C, and −17°C after pre‐activation, and more than half of the samples showed an increase in INP concentration. The increase in INP concentration has a positive correlation with the primary INP concentration before pre‐activation. The analyses provide new evidence that the pre‐activated INPs can act as better nuclei at temperature as warm as −10°C, and highlight the importance to find a way to consider this mechanism in models.

Kinetics, Products, and Brown Carbon Formation by Aqueous-Phase Reactions of Glycolaldehyde with Atmospheric Amines and Ammonium Sulfate.

Glycolaldehyde (GAld) is a C2 water-soluble aldehyde produced during the atmospheric oxidation of isoprene and many other species and is commonly found in cloudwater. Previous work has established that glycolaldehyde evaporates more readily from drying aerosol droplets containing ammonium sulfate (AS) than does glyoxal, methylglyoxal, or hydroxyacetone, which implies that it does not oligomerize as quickly as these other species. Here, we report NMR measurements of glycolaldehyde’s aqueous-phase reactions with AS, methylamine, and glycine. Reaction rate constants are smaller than those of respective glyoxal and methylglyoxal reactions in the pH range of 3–6. In follow-up cloud chamber experiments, deliquesced glycine and AS seed particles were found to take up glycolaldehyde and methylamine and form brown carbon. At very high relative humidity, these changes were more than 2 orders of magnitude faster than predicted by our bulk liquid NMR kinetics measurements, suggesting that reactions involving surface-active species at crowded air–water interfaces may play an important role. The high-resolution liquid chromatography–electrospray ionization–mass spectrometric analysis of filter extracts of unprocessed AS + GAld seed particles identified sugar-like C6 and C12 GAld oligomers, including proposed product 3-deoxyglucosone, with and without modification by reactions with ammonia to diimine and imidazole forms. Chamber exposure to methylamine gas, cloud processing, and simulated sunlight increased the incorporation of both ammonia and methylamine into oligomers. Many C4–C16 imidazole derivatives were detected in an extract of chamber-exposed aerosol along with a predominance of N-derivatized C6 and C12 glycolaldehyde oligomers, suggesting that GAld is capable of forming brown carbon SOA.

Effect of CO2 on the heterogeneous condensation of water vapor on insoluble fine particles

Heterogeneous condensation preconditioning technology has generated broad interest in removing fine particles from coal-fired flue gas due to its economic and environmental advantages. Here, a flow cloud chamber was used to study the effect of 0%–90% CO2 concentrations on the growth performance of insoluble fine particles with different operational conditions. The results suggest that a higher CO2 concentration in the particle growth environment is detrimental to the fine particles growth. The higher the CO2 concentration, the worse the growth performance. The adverse effect of CO2 on the growth performance decreases with the increase of growth time and the increase of supersaturation caused by temperature, and does not change significantly with the increasing particle concentration.

Experimental in vitro modeling of hematopoiesis by using diffusion chambers of an original design

One of the most important tasks of biotechnology and regenerative medicine is to achieve long-term expansion of hematopoietic stem cells. One of the promising approaches to optimizing the cultures of hematopoietic cells is the creation of a microenvironment in the form of feeder stromal layers, which allows for the reproduction of the combination of soluble cytokines and growth factors necessary for hematopoiesis and promotes an increase in their proliferation [1,2].

Effect of Superheat Steam on Ejector in Distilled Water Preparation System for Medical Injection.

In this study, a wet steam model was used to investigate the effect of steam superheat on ejector performance and non-equilibrium condensation phenomena. The simulation data for the ejector were validated with experimental data. The simulations show that an increase in primary flow superheat will increase the entrainment ratio, while an increase in secondary flow superheat will decrease the entrainment ratio. The output fluid superheat has little effect on the entrainment ratio. As the primary flow superheat increases from 0 to 20 K, the starting position of non-equilibrium condensation moves backward by 5 mm, and the mass fraction of condensed droplets decreases by 20%. The higher the secondary flow superheat, the lower the mass fraction of liquid in the diffusion chamber. The superheat level of the output fluid has no influence on the non-equilibrium condensation phenomenon of the ejector.

Advanced Online Monitoring of In Vitro Human 3D Full-Thickness Skin Equivalents.

Skin equivalents and skin explants are widely used for dermal penetration studies in the pharmacological development of drugs. Environmental parameters, such as the incubation and culture conditions affect cellular responses and thus the relevance of the experimental outcome. However, available systems such as the Franz diffusion chamber, only measure in the receiving culture medium, rather than assessing the actual conditions for cells in the tissue. We developed a sampling design that combines open flow microperfusion (OFM) sampling technology for continuous concentration measurements directly in the tissue with microfluidic biosensors for online monitoring of culture parameters. We tested our design with real-time measurements of oxygen, glucose, lactate, and pH in full-thickness skin equivalent and skin explants. Furthermore, we compared dermal penetration for acyclovir, lidocaine, and diclofenac in skin equivalents and skin explants. We observed differences in oxygen, glucose, and drug concentrations in skin equivalents compared to the respective culture medium and to skin explants.

Physical interpretation of theories of homogeneous electrolytes in the primitive model

The primitive model of ions is an important model system of electrolytes and ionic liquids because it is the simplest one to include both electrostatic and ion size effects. Here, two recent theories of the electrostatic excess chemical potential of homogeneous electrolytes modeled in the primitive model are analyzed. Both the Mean Countershell Approximation (MCSA) and the Extended Mean Spherical Approximation (MSAX) theories were already known to be accurate when compared to Grand Canonical Monte Carlo simulation results. The analysis here uncovers why these two seemingly very different theories agree very closely numerically. Moreover, knowledge of the physical meaning of the MCSA theory is used to define the MSAX theory’s terms as electrostatic interactions of ionic screening clouds. Lastly, a mathematical analysis of MCSA, MSAX, and a third theory is performed. This shows how all these theories—despite using very different mathematical and physical approximations—couple the distinct physical regimes of the low- and high-density limits to get accurate results at intermediate ion densities.

Fine Structure in Isotopic Peak Distributions Measured Using Fourier Transform Ion Cyclotron Resonance Mass Spectrometry: A Comparison between an Infinity ICR Cell and a Dynamically Harmonized ICR Cell

The fine structure of isotopic peak distributions of glutathione in mass spectra is measured using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) at 12 and 15 T magnetic field, with an infinity cell and a dynamically harmonized cell (DHC) respectively. The resolved peaks in the fine structure of glutathione consist of 2H, 13C, 15N, 17O, 18O, 33S, 34S, 36S, and combinations of them. The positions of the measured fine structure peaks agree with the simulated isotopic distributions with the mass error less than 250 ppb in broadband mode for the infinity cell and no more than 125 ppb with the DHC after internal calibration. The 15 T FT-ICR MS with DHC cell also resolved around 30 isotopic peaks in broadband with a resolving power (RP) of 2 M. In narrowband (m/z 307–313), our current highest RP of 13.9 M in magnitude mode was observed with a 36 s transient length by the 15 T FT-ICR MS with the DHC and 2ω detection on the 15 T offers slightly higher RP (14.8 M) in only 18 s. For the 12 T FT-ICR MS with the infinity cell, the highest RP achieved was 15.6 M in magnitude mode with a transient length of 45 s. Peak decay was observed for low abundance peaks, which could be due to the suppression effects from the most abundant peak, as result of ion cloud Coulombic interactions (space-charge).

Ontologies as Building Blocks of Cloud Security

Much like other processing domains, cloud computing is not surely safe. Security of cloud processing needs the same attention as any other aspect of cloud processing requires. Cyber world is shifting toward ontological technique and web 3.0 or web semantics for security. Cloud hosts servers demand more attention in context of security as number of resources and their access increases. Security measures have to be more extensive in cloud. Semantic web is usually new revolution inside the web science, which usually works upon base of ontologies. Ontologies are receiving great attention in the domain of computing and hence in the domain of security. This review paper examines different proposed “ontology centered techniques” and also provides a comprehensive analysis on these tactics. This research paper gives critical analysis of different models presented by different authors and researchers for ensuring security of a cloud based environment. This analysis helps different vendors of cloud technology to adapt one or all of these models to practically implement in their cloud machines whether they are offering IaaS, PaaS or SaaS. Any new security model using ontologies can also be proposed based on this study, as this paper gives a comprehensive comparison of the previously proposed ontologies for monitoring security state of cloud environment as safe or malicious.

Hygroscopicity and Ice Nucleation Properties of Dust/Salt Mixtures Originating from the Source of East Asian Dust Storms

Dust storms are common meteorological events that occur frequently in the late spring and early summer in arid and semi-arid areas. The resulting lofted dust and salt mixtures can impact atmospheric chemistry and climate systems through the many pathways represented by aerosol-cloud-climate interactions. In this study, dust/salt samples were collected from important sources of the East Asian dust storm, including the Badain Jaran Desert, the Tengger Desert and the Ulan Buh Desert in northwestern China. Ion chromatography (IC) measurements were performed to determine the concentrations of cations and anions. The ionic concentrations, pH and dissolvable fractions of sand samples show a positive correlation, indicating that the dissolved content is rich in alkaline ions. A positive matrix factorization (PMF) receptor model was employed to analyze the IC results, and from the PMF solutions non-obvious connections to local geography emerge. The results of hygroscopic experiments of sand samples which were measured by a vapor sorption analyzer indicate that the hygroscopicity may be related to the soluble content of samples, and the observed hygroscopic behavior can be well described by a thermodynamic model. The morphology of individual particles was chemically mapped by the synchrotron-based scanning transmission X-ray microscopy, and needle-shaped CaCO3 particles were observed to adhere to more irregular high K-containing particles. Moreover, a continuous flow diffusion chamber was used to investigate the ice nucleation abilities of typical salts, with both homogeneous freezing and deposition nucleation being observed. The results indicate that the salts primarily act as cloud condensation nuclei but can also act as ice nucleating particles at low temperatures.