Container Walls Research Articles

Model assessment on the non-isothermal methane biofiltration at ambient conditions

Direct anaerobic sewage treatment is increasingly adopted in several intertropical developing countries. The reduced carbon footprint of such facilities is based on its low electricity requirements and potential energy (biogas) recovery; however, if dissolved CH4 in the effluent is not controlled, this advantage will be drastically reduced. A suitable option to overcome this situation is to adopt CH4 desorption by an air stream, followed by bio-oxidation in compost biofilters. In such systems, the methanotrophic activity will increase the temperature in the biofilter to inhibiting values (above 40 °C), reducing the active volume of the compost media and its removal efficiency. This work addresses this process limitation, aiming to assess the temperature variations in the filter media and their effects on methane oxidation performance under different operating conditions. A comprehensive mathematical 2-D porous-medium based model was developed and then calibrated and validated with experimental data. The model considers heat, momentum, and mass balances under non-steady-state conditions, including heat exchange at the biofilter container wall influenced by daily ambient temperature fluctuations and solar radiation. Results obtained from 6 model simulations at different operating conditions show that temperatures above 40 °C are reached at the center-upper zones of the compost biofilter due to the heat transported from the methanotrophic active zones located at the bottom (inlet) and container wall. At midday (12 – 14 h), solar radiation on the wall contributes 14% of the total heat gained in a non-covered biofilter. The model highlights the importance of facilitating heat transport from the compost media to the surroundings; some practical recommendations are presented for that purpose.

In a behavioural bioassay, effluents from cigarette butts, cured tobacco and tree leaves differentially affect resting site selection in the land snail Cornu aspersum

ABSTRACT Cigarette butts (CBs) contain a plethora of chemicals, including many that are toxic. Although numerous studies have demonstrated the toxicity of CBs to aquatic organisms, there is less evidence that terrestrial organisms are severely impacted. Because CBs are commonly discarded on the ground, ground-dwelling organisms such as land snails may be especially affected. Many land snails are generalist detritivores/herbivores and ingest a variety of plant secondary compounds as they feed. This evolutionary exposure may render CBs (made principally of cured tobacco leaves) less toxic to these land snails than CBs are to less exposed aquatic animals. We investigated this possibility of reduced effects using a new behavioural assay to test the choice of ‘flavoured’ vertical resting sites in the land snail Cornu aspersum, which commonly rests on upright surfaces. In four experiments, regions of container walls were coated with different concentrations of CB and cured tobacco effluents, and effluents from three tree species and cured tobacco. Snails avoided high CB and tobacco effluent concentrations, which is consistent with toxicity. However, snails preferentially rested on dilute concentrations of both CBs and tobacco. Preference among tree leaf effluents was less evident, with a trend towards snails preferring the more readily eaten maple than the less readily eaten oak. Selection of the preferred tobacco concentration did not differ from that of tree leaves, indicating that C. aspersum was not repelled by dilute tobacco effluent. These results indicate that compounds leaching from discarded CBs may have little effect on snails and perhaps other soil organisms under environmentally realistic conditions.

Combined Longitudinal and Surface Acoustic Wave Analysis for Determining Small Filling Levels in Curved Steel Containers.

Measurement of the small filling levels in closed steel container systems is still a challenge. Ultrasound, however, is a sensitive and non-invasive technique and is suitable for online monitoring. This study describes a new ultrasonic sensor system for sensing small filling levels using longitudinal and surface acoustic wave analysis. The sensor system consists of one transducer for the longitudinal wave analysis and two transducers for the longitudinal and surface acoustic wave analysis. All transducers were mounted to the outer wall of the steel container, ensuring non-invasiveness, and a filling level ranging from 0 to 5 cm was investigated. Combining both approaches, a consistent determination of small filling levels was achieved for the entire measuring range (R2 = 0.99).

Treelike thermal structures on the water surface

Unusual treelike thermal structures can be formed on the free surface of the evaporating water in small containers. These structures are studied in detail for the first time, and it has been established that under certain parameters (the container diameter is about 90 mm, the water layer thickness is 6–15 mm, and the container wall temperature is 28–47 °C), they are the most probable and pronounced. The presence of both horizontal and vertical temperature gradients is fundamental for the formation of such structures. An attempt has been made to numerically model treelike structures. It is shown that the classical model of heat and mass transfer in a fluid, taking into account the mechanisms of heat transfer on the free surface, usually used for water, and the reference coefficient of the surface tension of water, does not even allow one to qualitatively predict the observed treelike structures on the water surface. A hypothesis about the need to consider the influence of impurities on heat and mass transfer near the water surface has been proposed.

Tritium as a Tracer of Leachate Contamination in Groundwater: A Brief Review of Tritium Anomalies Method

Environmental isotopes are essential in hydrogeological studies, thanks to their contribution to the understanding of aquifers dynamics, vulnerability, water resources assessment, and management issues. The environmental isotopic approach plays a vital role in tracing the hydrological cycle and identifying various sources of contamination in the environment and gives independent information concerning what can be determined by a traditional hydrogeological study. Even in the framework of COP-26, isotopes have been indicated as fingerprints of climate change and therefore suitable for the evaluation of water balance and assessment of processes involved therein; in pollution studies they are used as fundamental support of traditional geochemical measures. Tritium, in particular, has been used since the 1960s to identify potential leaks in the containment walls of waste disposal sites, since its presence in the leachate (at very high levels in some cases) depends on the incorrect waste disposal of some peculiar items. Its use as a tracer of pollution by landfills is highlighted and emphasized by the very low concentrations of tritium in the natural environment. By comparing tritium content of leachate to that of water downflow from the waste disposal site, it is therefore possible to establish with a good success rate whether leachate have migrated or not out of the landfill, in the surrounding environment. An additional potential of tritium is to give a prompt indication of pollution risk in the environment indicating leaching even before the chemical indicator of pollution can be detected. This article wants to provide a contribution to the scientific community, collecting all the existing research in this field and providing data and benchmarks about this method, in particular stressing the role of tritium as an indicator of leachate transfer out of waste disposal sites.

Heat capacity of liquid transition metals obtained with aerodynamic levitation

The development of contactless measurement methods has allowed investigating the properties of molten materials at high temperatures in a controlled environment. As the sample is not in contact with any container walls while being heated, levitation techniques have an edge over traditional contact methods at elevated temperatures. Among the various thermophysical properties of interest, it has been challenging to measure heat capacity with levitation techniques because it is directly related to the emissivity of the sample. Previous studies on heat capacity measurement with various levitation techniques have produced results with large deviations, especially at elevated temperatures. In addition, there is a general lack of information on the heat capacity of liquid transition metals at temperatures exceeding 2000 K, especially using conventional calorimetry methods. In this study, we successfully obtained the isobaric heat capacity of liquid transition metals such as Co, Hf, Ir, Mo, Nb, Rh, Ru, Ti, V, and Zr with aerodynamic levitation using the newly developed “multiple-gas cooling” method. A comparison between our reported values and reference data enabled us to assess the accuracy of previous experiments and provide much needed heat capacity data for high-temperature liquid metals. This study highlights the applicability and reliability of the multiple-gas cooling method for measuring the heat capacity of liquid non-noble metals at temperatures approaching 3000 K.

Study on the Effect of Jet Position and Size on Heat Transfer in a Small Containment

In the main steam line break (MSLB) accident, the rise in temperature and pressure threatens the integrity of the containment, which is caused by a large amount of mixed gas injected into the containment rapidly. Due to the structural difference between small and large containment, it is necessary to study the heat transfer in the complex space of the small containment. Based on the research method, which is from simple to complex, in this study, a series of experiments and numerical simulations are carried out with different jet positions and sizes using hot air without phase change as the working medium. The results show that the temperature field above the jet is complex and affected by many factors such as buoyancy, initial kinetic energy, and internal structure. When the jet flow rate is constant, the jet size is smaller and the velocity is faster, which results in a large circulation and stronger heat exchange with the wall of containment. This means that the temperature above the jet is lower than the large jet size, and the temperature below the jet is slightly higher. The jet position mainly affects the relative position of the jet and the complex space in the containment. When the jet is located in a narrow space, the overall temperature in the containment is higher than the jet located in a large space. In addition, when it is close to the obstacle, the core region of the jet will shift slightly toward the obstacle.

TinyLev acoustically levitated water: Direct observation of collective, inter-droplet effects through morphological and thermal analysis of multiple droplets

HypothesisUnderstanding the crystallization of atmospheric water can require levitation techniques to avoid the influence of container walls. Recently, an acoustic levitation device called the TinyLev was designed, which can levitate multiple droplets at room temperature. Proximal crystallization may affect droplet phase change and morphological characteristics. MethodologyIn this study, acoustically levitated pure water droplets were frozen individually and in pairs or triplets using a TinyLev device. Nucleation, bulk crystal growth, and melting were observed using digital and infrared cameras concurrently. FindingsInitially, the acoustic field forced the droplets into an oblate spheroid shape, though the counteracting force of the cooling stream caused them to circularize. Droplet geometry was thus the net result of streaming forces and surface tension at the acoustic boundary layer/air–liquid interface. Nucleation was determined to be neither homogeneous nor heterogeneous but secondary, and thus dependent on the cooling rate and not on the degree of supercooling. It was likely initiated by aerosolized ice particles from the air or from droplets that had already nucleated and broken up. The latter secondary ice production process resulted in multi-drop systems with statistically identical nucleation times. Notably, this meant that the presence of interfacial rupture at an adjacent droplet could influence the crystallization behaviour of another. After the formation of an initial ice shell around the individual droplets, dendritic protrusions grew from the droplet surface, likely seeded by the same ice particles that caused nucleation, but at a quasi-liquid layer. When freezing was complete, it was determined that the frozen core had undergone a volumetric expansion of 30.75%, compared to 9% for pure, sessile water expansion. This significantly greater expansion may have resulted from entrained air bubbles at the inner solid–liquid interface and oscillations at the moving phase boundary caused by changes in local acoustic forces. Soon after melting began, acoustic streaming, the buoyancy of the remaining ice, and convective currents caused by both an inner thermal gradient and thermocapillary effects along the air–liquid interface, all contributed to the droplet spinning about the horizontal axis.

Benchmark VERCORS 2022: mechanical response of the prestressed concrete containment wall to ambient conditions

The VERCORS benchmark was developed to provide a solid experimental basis for numerical modeling of concrete containment buildings (CCBs) to extend their lifespan. The goal of the first phase of the third benchmark is to present a blind prediction of CCB’s behavior across the whole lifespan and under periodic pressure tests. This paper summarizes the calibration of the material model based on the Microprestress-solidification (MPS) theory according to the provided laboratory experimental data. A special emphasis is given to the influence of the ambient conditions on drying creep and transient thermal creep of concrete and the calibration of the corresponding material parameters. These phenomena are studied on a representative section of the containment wall using weakly coupled thermo-hygro-mechanical analyses.

Methods to stabilize aqueous supercooling identified by use of an isochoric nucleation detection (INDe) device

Stable aqueous supercooling has shown significant potential as a technique for human tissue preservation, food cold storage, conservation biology, and beyond, but its stochastic nature has made its translation outside the laboratory difficult. In this work, we present an isochoric nucleation detection (INDe) platform for automated, high-throughput characterization of aqueous supercooling at >1 mL volumes, which enables statistically-powerful determination of the temperatures and time periods for which supercooling in a given aqueous system will remain stable. We employ the INDe to investigate the effects of thermodynamic, surface, and chemical parameters on aqueous supercooling, and demonstrate that various simple system modifications can significantly enhance supercooling stability, including isochoric (constant-volume) confinement, hydrophobic container walls, and the addition of even mild concentrations of solute. Finally, in order to enable informed design of stable supercooled biopreservation protocols, we apply a statistical model to estimate stable supercooling durations as a function of temperature and solution chemistry, producing proof-of-concept supercooling stability maps for four common cryoprotective solutes.

Hydrodynamic ram analysis in high-speed projectile penetrating into water-filled vessels

Hydrodynamic ram (HRAM) is a phenomenon that occurs when a high-speed projectile penetrates a fluid-filled tank, where the energy transferred to the liquid could result in a catastrophic failure and excessive structural damage. It is essential to take physical comprehension of the hydrodynamic effects that occur during an HRAM event in the civilian domain as well as for the military aircraft design, which would in fact contribute to design better structures with respect to this particular threat. For this present work, the HRAM due to cavity evolution in confined vessels under ballistic impact by projectiles was investigated through theoretical analysis combined with experimental results. Taking the confinement effects due to the limited size of the fluid-filled vessel and corresponding structure deformation into account, a model is proposed to describe the pressure between the liquid and vessel wall along the penetration trajectory based on cavity dynamics analysis. By studying relevant parameters, changes of wall pressure, non-dimensional disturbance range and energy of two extreme containers, (namely, non-pressure resistance containers and rigid containers without deformation) were examined. The results show that the cavitation pressure has less intense peak but much greater temporal extent compared with the pressure generated during the shock stage, thereby the cavity pressure impulse induced by cavity evolution is a non-negligible factor affecting the deformation and failure of a fluid-filled vessel. The aim of the present work is to reveal the mechanism of the pressure acting on the container wall caused by cavity evolution rather than the initial shock wave in an HRAM event, which will help to study the nature of hydrodynamic ram and understand the role of the cavitation pressure in the damage or deformation of liquid-filled vessels under projectile impact.

Spin-up in a semicircular cylinder

We report experimental and theoretical results on how a fluid (homogeneous or continuously stratified) is spun up in a closed, semicircular cylinder. Experiments were performed for Rossby numbers $Ro=0.02$, 0.2 and 1 (the latter corresponding to the limiting case of spin-up from rest), with the Ekman number $E=O({10^{-5}})$, and the Burger number ($S$) varied between 0 and 10. There are two key processes: Ekman pumping that drives the core flow; and the formation and breakdown of the vertical-wall boundary layers, with respective characteristic time scales $t\sim E^{-1/2}$ and $Ro^{-1}$. When these time scales are comparable, the observed flow is dominated by the gradual spin-up of the initial anticyclone that forms when the rotation rate is increased, which fills the container's interior; vorticity generated adjacent to the vertical walls throughout remains confined to the neighbourhood of the container's walls and corners. Conversely, when ${E^{1/2}/Ro\ll 1}$, the vertical-wall boundary layers rapidly break down, resulting in the formation of cyclonic vortices in the container's vertical corners, which grow and interact with the initial anticyclone, leading to the formation of a three-cell flow pattern. For $Ro=0.02$, our theoretical description of the flow generally agrees well with experiments, and the computation of the eruption times for the unsteady boundary layers is consistent with the observations for both $Ro=0.02$ and $Ro=0.2$.

Insulin aggregation starts at dynamic triple interfaces, originating from solution agitation

The consequences of agitation on protein stability are particularly relevant to therapeutic proteins. However, the precise contribution of the different effects induced by agitation in pathways leading to protein denaturation and aggregation at interfaces is not entirely understood. In particular, the contribution of a moving triple line, induced by the sweeping of a solution meniscus on a container wall upon agitation, has only been rarely assessed.In this article, we therefore designed experimental setups to analyze how mixing, shear stress, and dynamic triple interfaces influence insulin aggregation in physiological conditions. This has been achieved by controlling agitation speed, shear stress, and the extension of triple interfaces in order to shed light on the contribution of different agitation-induced effects on insulin aggregation in physiological conditions.We demonstrate that strong agitation is necessary for the onset of insulin aggregation, while the growth of the aggregates is sustained even under weak agitation. Kinetic insulin aggregation studies in conditions of intermittent wetting show that the aggregation rate correlates with the amount of dynamic triple interfaces that the proteins are exposed to. Finally, we demonstrate that the triple line, where the protein solution, the air, and a hydrophobic surface meet constitutes a preferential early aggregation site.

A Model to Simulate Gas Dissolution into/through Metals and Its Application to Deuterium in a 316L Steel Chamber with Pb-Li in a Quasi-2D Geometry

Liquid lead-lithium in eutectic proportions (Pb-Li) is a candidate material for Breeding Blankets (BBs) in future Fusion Power Plants (FPP). BB design depends on the diffusivity and Sieverts’ constant (solubility) of tritium in this alloy, but literature reports a large scattering of measurements for these values. A model was developed to address one possible source of this scattering in static experiments, i.e., non-negligible loss of hydrogen gas through steel walls of containers. This model simulates the dissolution of gases into, and their diffusion through, metallic barriers for diffusivity and Sieverts’ constant as inputs. When implemented, it can be used to compute the pressure decrease in a metallic chamber, and comparison of simulated curves with experimental ones allows for estimates of the diffusivity and Sieverts’ constant. This approach was used to estimate these coefficients for deuterium in stainless steel, using experiments performed with a 316L steel chamber from an existing facility (the Vacuum Sieve Tray setup) and simulations in a quasi-2D representation of this chamber. This validated the model, which was then used to simulate the chamber containing Pb-Li, as a means of planning for future experiments.

Thermal and optical properties of (25-x)LaO3/2–25TiO2–25NbO5/2–25WO3–xZrO2 glasses with high refractive indices prepared by aerodynamic levitation method

With the concept of aerodynamic levitation technology, we had successfully prepared the high-entropy amorphous oxides with the composition of (25-x)LaO3/2–25TiO2–25NbO5/2–25WO3–xZrO2 using containerless equipment. The glass formation range was found to be 0 ≤ x ≤ 10. Besides, the advantage of this method is that by suppressing inhomogeneous nucleation from the container wall, molten materials can easier reach a deep undercooling degree. The effects of ZrO2 substitution on the optical, and thermal properties of 25LaO3/2–25TiO2–25NbO5/2–25WO3 glasses were evaluated. Based on temperature gap and critical cooling rate, sample 25LaO3/2–25TiO2–25NbO5/2–25WO3 has the best amorphous forming ability with temperature gap is 65 °C and critical cooling rate is 11.5 °C/s. In the visible region, all refractive indices are over 2.15 and the Abbe number of 25LaO3/2–25TiO2–25NbO5/2–25WO3 is the highest, up to 23.6. In a wide window ranging from 0.375 to 7.5 μm, they also exhibit high transmittances. The excellent mechanical properties are presumed to be due to the complex interactions between atoms caused by high-entropy. In terms of application, the glasses are potentially applicable to lenses, next-generation optical disks, and endoscopes.

Decreasing Phosphorus Fertility to Reduce Sweetpotato Root Growth During Container-grown Transplant Production

AbstractSweetpotato [Ipomoea batatas (L.) Lam.], grown as an edible ornamental, is propagated in home gardens using locally purchased transplants. However, vigorous growth of sweetpotato limits the period of transplant salability due to root confinement. The objective of the experiment was to evaluate reductions in phosphorus (P) fertility to slow transplant root growth and extend the period of salability. Cuttings were planted into containers and fertilized at 0, 5 (0.0007), 10 (0.0012), 15 (0.0020), 20 (0.0024), and 31 mg P.L −1 (0.0040 oz P.gal−1) using a modified Hoagland solution. All transplants fertilized at ≥5 mg P.L −1 increased in shoot length, color, and biomass during the first four weeks after planting (WAP) but declined thereafter. Transplant roots fertilized at ≥5 mg P.L −1 (0.0007 oz P.gal−1) increased in total length, surface area, and volume throughout the six-week production cycle. However, P fertility <15 mg.L -1 (0.0020 oz P.gal−1) resulted in narrower storage roots with lower root volumes. Reducing P fertility from 31 (0.0040 oz P.gal−1) to 5 mg L −1 (0.0007 oz P.gal−1) did not sufficiently slow transplant rooting to prevent roots from reaching container walls to extend the period of salability.Index words: root length, root diameter, root biomass, and root architecture.Species used in this study: Sweetpotato [Ipomoea batatas (L.) Lam.].

Significance to the Horticulture Industry

Significance to the Horticulture Industry

Highly effective removal of microplastics by microalgae Scenedesmus abundans

The highly effective removal of multiple kinds of microplastics (MPs) by microalgae Scenedesmus abundans was accomplished and the main mechanism of the MPs removal was identified as hetero-aggregation. The accurate quantification of removal efficiency was achieved by quantifying free suspended microparticles before and after the microalgae treatment. Scenedesmus abundans was tested against three kinds of plastics, including polystyrene (PS), poly(methyl methacrylate) (PMMA), and polylactide (PLA), and a total removal efficiency (η) higher than 84% was achieved for all MPs. Among these MPs, S. abundans were highly effective for removing PMMA microparticles (η = 98%). For the other two kinds of MPs, pre-exposure was required to achieve a total removal efficiency higher than 70%. As validated by SEM, a long-term exposure to MPs (greater than 2 days) promoted the formation of bound extracellular polymeric substances (EPS) and hetero-aggregation, leading to a much higher fraction of MPs removed by aggregations (ηa greater than 70%). On the contrary, if MPs exposure is short, enhanced adsorption onto solid surfaces can play an important role in the MPs removal, especially in the case of PLA. In this aspect, the abundance of soluble EPS was proportional to the amount of MPs adsorbed onto the container wall. These results suggest that the removal efficiency of microplastics, as well as the underlying mechanism, was affected by both plastic kind and exposure duration. Pre-exposure to MPs greatly increased the removal efficiency and can be a promising strategy for real-life practices.

Improvement of radio frequency heating uniformity in wheat kernels with aluminum foil sheets covered on rectangular container walls

Improving radio frequency (RF) heating uniformity is a key to obtain a good pasteurization effect while maintaining the quality of food product. The objective of this study was for providing a new method to improve the RF heating uniformity by adding aluminum foil sheets around the container walls. A 27.12 MHz, 6 kW pilot-scale RF system at an electrode gap of 110 mm was used to evaluate the heating rate and temperature distribution of wheat kernels in a rectangular container with the location, size and thickness of the foil sheet. The results showed that the RF heating behavior was influenced by foil sheets added at different oriented walls of the container. A cold spot area appeared in the place closed to the foil sheet wall at the vertically oriented addition, while a cold spot in the center and hot spots in the corners and edges still existed with the horizontally oriented addition of the sheet. The presence of foil sheet had an influence on the voltage, power input and energy efficiency. Effect of different foil sheet wall on heating behavior of samples was related to the reflection of foil sheet to RF electromagnetic wave. The heating uniformity index (λ) value decreased when the foil sheet was placed at the container bottom wall, and with increasing foil sheet size and thickness. A clearly improved RF heating uniformity can be obtained by increasing foil sheet size and thickness at the container bottom wall.

Derechos humanos de niños, niñas, adolescentes y mujeres migrantes en los instrumentos internacionales

Desde la perspectiva de las Relaciones Internacionales y el constructivismo se analizan los instrumentos internacionales que abogan por los derechos humanos de niños, niñas, adolescentes y mujeres migrantes durante el proceso de movilidad. Se examina la correspondencia entre los instrumentos y sus implementaciones en el caso de la crisis humanitaria de 2013 y 2014 en Estados Unidos. Se abordan las políticas migratorias actuales entre México y Washington, para explicar y comprender por qué México está funcionando como muro de contención de centroamericanos, africanos y sudamericanos. Se exponen las propuestas de la Agenda 2030 y el Pacto Mundial sobre Migración que buscan regular y ordenar los flujos migratorios, ponderando la protección de los derechos humanos de migrantes, lo que se convierte en un reto ante el retiro de Estados Unidos y otros países del Pacto. Se construye una tipología de migrantes retornados distinguiendo entre el retorno voluntario e involuntario.