Liquid Reservoir Research Articles

The emission properties, structure and stability of ionic liquid menisci undergoing electrically assisted ion evaporation

The properties and structure of electrically stressed ionic liquid menisci experiencing ion evaporation are simulated using an electrohydrodynamic model with field-enhanced thermionic emission in steady state for an axially symmetric geometry. Solutions are explored as a function of the external background field, meniscus dimension, hydraulic impedance and liquid temperature. Statically stable solutions for emitting menisci are found to be constrained to a set of conditions: a minimum hydraulic impedance, a maximum current output and a narrow range of background fields that maximizes at menisci sizes of 0.5–3 ${\rm \mu}{\rm m}$ in radius. Static stability is lost when the electric field adjacent to the electrode that holds the meniscus corresponds to an electric pressure that exceeds twice the surface tension stress of a sphere of the same size as the meniscus. Preliminary investigations suggest this limit to be universal, therefore, independent of most ionic liquid properties, reservoir pressure, hydraulic impedance or temperature and could explain the experimentally observed bifurcation of a steady ion source into two or more emission sites. Ohmic heating near the emission region increases the liquid temperature, which is found to be important to accurately describe stability boundaries. Temperature increase does not affect the current output when the hydraulic impedance is constant. This phenomenon is thought to be due to an improved interface charge relaxation enhanced by the higher electrical conductivity. Dissipated ohmic energy is mostly conducted to the electrode wall. The higher thermal diffusivity of the wall versus the liquid, allows the ion source to run in steady state without heating.

Chemomechanical equilibrium at the interface between a simple elastic solid and its liquid phase.

Applying diffusion coupled deformation theory, we investigate how the elastic properties of a solid body are modified when forced to keep its chemical potential aligned with that of its melt. The theory is implemented at the classical level of continuum mechanics, treating materials as simple continua defined by uniform constitutive relations. A phase boundary is a sharp dividing surface separating two continua in mechanical and chemical equilibrium. We closely follow the continuum theory of the swelling of elastomers (gels) but now applied to a simple two phase one-component system. The liquid is modeled by a local free energy density defining a chemical potential and hydrostatic pressure as usual. The model is extended to a solid by adding a non-linear shear elastic energy term with an effective modulus depending on density. Imposing chemomechanical equilibrium with the liquid reservoir reduces the bulk modulus of the solid to zero. The shear modulus remains finite. The stability of the hyper-compressible solid is investigated in a thought experiment. A mechanical load is applied to a rectangular bar under the constraintof fixed lateral dimensions. The linear elastic modulus for axial loading is evaluated and found to be larger than zero, implying that the bar, despite the zero bulk modulus, can support a weight placed on its upper surface. The weight is stabilized by the induced shear stress. The density dependence of the shear modulus is found to be a second order effect reducing the density of the stressed solid (chemostriction).

Effect of heater wire configuration and nanotexturing on force generated by self-propelled bubble-driven propeller

The heat generated on a heater submerged in a liquid reservoir is transported away by rising bubbles during pool boiling under buoyancy conditions. This bubble-driven heat transport cools the heater surface, and as a result, the critical heat flux (CHF) is delayed, or even avoided. At detachment from the heated surface, bubbles undergo necking owing to the interplay between evaporation, buoyancy, vapor recoil, and surface tension. The surface tension tends to hold a bubble at the heater surface, whereas the buoyancy force pulls it apart. On the other hand, vapor recoil pushes the heater downwards. Eventually, in many cases the buoyancy force prevails because of the evaporation-driven volume growth of the bubbles, and their detachment. Here, we observe that during bubble detachment, the heater is propelled in the direction of the rising bubbles. This self-propelled motion can be used to shed bubbles, which enhances the pool boiling performance. In this work, we study the heater shaped as a ‘wavy’ wire and demonstrate the extent to which the bubble-driven force and its direction and magnitude depend on a particular way of the in-plane wavy heater wire installation. The heating wire was installed at the upper (top) or lower (bottom) surfaces of a plate and also, two wire heaters were installed at both surfaces of the plate, and the supplied heat was maintained at a constant level. It was found that the case where the wire heater installed at both surfaces of the plane heater yielded the strongest self-propelled motion. In an additional investigation, the heating wire was nanotextured with nickel nanocones electroplated on its surface. The nanotextured heater surface increased the number of bubble nucleation sites and thus magnified the corresponding force for all the heater wire installations, compared to those in the non-textured cases.

Convection behind the Humidification of Titan’s Stratosphere

Abstract On Titan, methane is responsible for the complex prebiotic chemistry, the global haze, most of the cloud cover, and the rainfall that models the landscape. Its sources are located in liquid reservoirs at and below the surface, and its sink is the photodissociation at high altitude. Titan’s present and past climates strongly depend on the connection between the surface sources and the atmosphere upper layers. Despite its importance, very little information is available on this topic. In this work, we reanalyze two solar occultations made by Cassini before the northern spring equinox. We find a layer rich in methane at 165 km and at 70°S (mixing ratio 1.62% ± 0.1%) and a dryer background stratosphere (1.1%–1.2%). In the absence of local production, this reveals an intrusion of methane transported into the stratosphere by convective circulation. On the other hand, methane transport through the tropopause at a global scale appears quite inhibited. Leaking through the tropopause is an important bottleneck of Titan’s methane cycle at all timescales. As such, it affects the long-term evolution of Titan’s atmosphere and the exchange fluxes with the surface and subsurface reservoirs in a complex way. Global climate models accounting for cloud physics, thermodynamical feedbacks, and convection are needed to understand the methane cycle, and specifically the humidification of the stratosphere, at the present time, and its evolution under changing conditions at a geological timescale.

Numerical Modelling of Heat Transport in Freezing Mortars with an External Liquid Reservoir

Abstract Several studies indicate that the temperature distribution in concrete may affect the extent of frost scaling. This study presents a numerical model that describes the thermal response of freezing mortars in the presence of an external liquid reservoir, where the external liquid is either pure water or 3% sodium chloride solution. The phase transformation of supercooled external liquid is modelled in two stages: quick freezing, when the supercooled liquid starts to form crystals and slow freezing. The model is developed in two parts. In part I, the focus is the modelling of external liquid, and therefore a non-porous body with an external liquid reservoir is modelled and validated. In part II, the model developed in part I is developed further for a porous body containing different phases, i.e., unfrozen liquid and ice, in the pores. A comparison of simulated and experimentally measured temperature distributions shows a good agreement.

Insight into the Methods for Improving the Utilization Efficiency of Fracturing Liquid in Unconventional Reservoirs

A large amount of fracturing fluid will be injected into the unconventional reservoirs during hydraulic fracturing. At present, the maximum amount of fracturing fluid injected into shale oil reaches 70000 m3 in Jimsar. The main function of fracturing fluid is to make fractures for traditional reconstruction of fracturing; for unconventional reservoirs, fracturing fluid is also used to increase formation energy by large-scale injection. It is of great significance to improve the utilization efficiency of large-scale hydraulic fracturing fluid for shale oil to increase production and recovery. In this study, the method of improving the utilization efficiency of the large-scale hydraulic fracturing fluids is explored by experiment, numerical simulation, and field test of Jimsar shale oil formation. This research shows that fracture complexity can effectively increase the contact area between the fracturing fluids and the formation. The water absorption rate of the fractured core is increased, which lays the foundation for improving the liquid utilization efficiency. Reasonably, well shutting before production ensures the pressure balance in the fractures, and the fluid pressure can be transmitted to the far end, which improves the fracture effectiveness, increases formation energy, and promotes imbibition and oil displacement. By using the additive of enhanced imbibition displacement, the displacement efficiency and the displacement amount of crude oil in the micro-nanopores can be greatly improved, and the utilization ratio of liquid can be further enhanced. The experiment adopted in the field proves that improving energy utilization efficiency has an important impact on production. This study has great guiding significance for the efficient development and practical production of unconventional reservoirs.

Wetting transition of the confined receding meniscus with tailing bead formation

Wetting transition of the confined receding meniscus is determined by two independent mechanisms, related to the apparent receding contact angle and the inclined contact lines, respectively. The coexistence of the two mechanisms impacts the geometry of the meniscus. An experiment is designed to observe the shape of a confined droplet when it is horizontally stretched by a plate. It is found that wetting transition is delayed with a tailing bead formed in the rear of the confined receding meniscus, and occurs at the critical point determined by the microscopic physical characteristics in the inner region of the contact line. Through experimental and numerical analysis, the confined droplet is found to be characterized similarly to the classical models of the liquid film on a plate vertically dragged out of a liquid reservoir and the droplet sliding on an inclined plane. The formation of the tailing bead is owing to the balance of viscosity and capillarity, and its shape can be described in the framework of lubrication theory. However, the tailing bead also shows some unique features. The formation of tailing bead marks that the dominant features of the meniscus convert from two-dimensional ones to three-dimensional ones; besides, it is irrelevant to gravity. The tailing bead formation and the selection of critical point reflect that the physical principles of the inner contact line region have a stronger influence on wetting transition than those of the outer contact line region. • The tailing bead of the confined receding meniscus is observed and investigated. • Wetting transition is delayed by the tailing bead and inclined contact lines. • Meniscus shapes are respectively modeled for the low and high capillary number. • The dominant meniscus characteristics turn from two-dimensional into three-dimensional. • Microscopic physical characteristics near the contact line strongly impact wetting transition.

VIS-IR spectroscopy of magnesium chlorides at cryogenic temperatures

Chlorinated compounds have been recently identified or suggested to exist in a number of planetary bodies such as Ceres, Europa, Ganymede, Enceladus and Mars, on the basis of remote sensing and in-situ measurements as well as Earth-based telescopic observations. Sodium and magnesium-bearing chlorinated compounds with different levels of hydration have been suggested to reach the surface of these bodies through ascending flows from the interior; thus, such materials could be geochemically related to the putative presence of subsurface liquid reservoirs and could bring precious information about those layers' salty composition. Laboratory spectroscopic data of chlorinated salts carried out at temperatures representative of real planetary bodies, fundamental to correctly interpret the observational data, are currently missing or incomplete.Here we present laboratory reflectance spectra of two hydrated magnesium chlorides, namely MgCl2•2H2O and MgCl2•6H2O, measured at three different grain sizes and at twelve temperature values in the range 80÷295 K. All spectra have been measured in the visible and infrared spectral range 0.5÷4.7 μm. We examined the absorption features and related spectral parameters as a function of both temperature and grain size. These reflectance spectra, as far as the infrared range beyond 2.5 μm is concerned, are the first measured and published at cryogenic temperatures, therefore these data may prove very useful for the interpretation and modeling of remote sensing spectral data from planetary missions. In particular, this new dataset will be helpful in applying spectral unmixing models to past and future observations of some icy satellites, Mars, Ceres, and possibly other Solar System bodies.

Development of adsorption ratio equation and state equation of liquid and their geological significance

There have been many theories to describe adsorbed or free gas. However, quantitative description of the occurrence characteristics of liquids in porous media has always been a great challenge due to a lack of basic theory. Through years of research, two theoretical equations, i.e., adsorption ratio equation and state equation of liquid, have been proposed to describe the characteristics of liquids in porous media, and revealed the mechanism of liquid occurrence. Further, a quantitative evaluation technology for the microscopic distribution of liquids was established by combining nuclear magnetic resonance theory. This research will be of great significance for studying the microscopic distribution of liquids in tight reservoirs, such as shale, coal, and tight sandstone. Cited as: Li, J. Development of adsorption ratio equation and state equation of liquid and their geological significance. Capillarity, 2021, 4(4): 63-65, doi: 10.46690/capi.2021.04.01

Spray characteristics of an ultrasonic microdroplet generator with a continuously variable operating frequency.

Droplet spraying is utilized in diverse industrial processes and biomedical applications, including nanomaterial synthesis, biomaterial handling, and inhalation drug delivery. Ultrasonic droplet generators transfer energy into bulk liquids using acoustic waves to disrupt the free liquid surface into fine microdroplets. We previously established a method combining ultrasonic actuation, resonant operation, and acoustic wave focusing for efficient spraying of various liquids (e.g., low surface tension fuels, high viscosity inks, and suspensions of biological cells). The microfabricated device comprises a piezoelectric transducer, sample reservoir, and an array of acoustic horn structures terminated by microscale orifices. Orifice size roughly dictates droplet diameter, and a fixed reservoir height prescribes specific device resonant frequencies of operation. Here, we incorporate a continuously variable liquid reservoir height for dynamic adjustment of operating parameters to improve spray efficiency in real-time and potentially tune the droplet size. Computational modeling predicts the system harmonic response for a range of reservoir heights from 0.5 to 3 mm (corresponding to operating frequencies from ∼500 kHz to 2.5 MHz). Nozzle arrays with 10, 20, and 40 μm orifices are evaluated for spray uniformity and stability of the active nozzles, using model predictions to explain the experimental observations.

Hydrogen defects in feldspars: kinetics of D/H isotope exchange and diffusion of hydrogen species in alkali feldspars

Diffusion of hydrogen in natural alkali feldspars (Eifel sanidine and adularia from unknown locality) containing strongly bonded OH defects was investigated by D/H isotope exchange in the T range 600–1050 °C at ambient pressure and at elevated pressures up to 8 kbar. Runs at 1 atm were performed in a fused silica tube connected to a liquid D2O reservoir at room temperature. In the high- pressure experiments samples were sealed with D2O in gold capsules and processed up to 4 kbar in externally heated pressure vessels using Ar/D2O as the pressure medium. Experiments at 6–8 kbar were performed in an internally heated gas pressure vessel using the double capsule technique to minimize isotopic contamination by the pressure medium. Diffusion coefficients were determined either by measuring concentration-distance profiles of OH and OD with an IR microscope or by measuring the total exchange of oriented plates after various run durations using a macroscopic IR technique. Both methods gave consistent data. D/H interdiffusion, DD/H, is almost identical in the adularia and in the sanidine implying that the chemical composition and the degree of Al/Si disorder have minor influence on the hydrogen isotope exchange in alkali feldspars. Furthermore, no effect of crystallographic orientation was found for DD/H in both feldspars. DD/H in sanidine, however, depends on the thermal pre-treatment. Heating for several days at 900 °C leads to a lowering of D by a factor of 2.3, indicating a corresponding decrease in mobile hydrogen species. Data for sanidine pre-annealed at 900 °C are well described in the T range 600–1050 °C by DD/Hm2/s=6.9·10-6exp-162kJ/molR·T\\documentclass[12pt]{minimal}\t\t\t\t\\usepackage{amsmath}\t\t\t\t\\usepackage{wasysym}\t\t\t\t\\usepackage{amsfonts}\t\t\t\t\\usepackage{amssymb}\t\t\t\t\\usepackage{amsbsy}\t\t\t\t\\usepackage{mathrsfs}\t\t\t\t\\usepackage{upgreek}\t\t\t\t\\setlength{\\oddsidemargin}{-69pt}\t\t\t\t\\begin{document}$$~D_{{{\\text{D/H}}}} \\left( {{\\text{m}}^{2} {\\text{/s}}} \\right) = 6.9 \\cdot 10^{{ - 6}} \\exp \\left( {\\frac{{ - 162{\\text{~kJ}}/{\\text{mol}}}}{{R \\cdot T}}} \\right)$$\\end{document}The diffusivity is strongly enhanced by water pressures (PH2O), i.e., in the range of 0–2 kbar. At PH2O = 2 kbar the following equation applies in the T-range of 645–800 °C: DD/Hm2/s=1.2·10-6exp-131kJ/molR·T\\documentclass[12pt]{minimal}\t\t\t\t\\usepackage{amsmath}\t\t\t\t\\usepackage{wasysym}\t\t\t\t\\usepackage{amsfonts}\t\t\t\t\\usepackage{amssymb}\t\t\t\t\\usepackage{amsbsy}\t\t\t\t\\usepackage{mathrsfs}\t\t\t\t\\usepackage{upgreek}\t\t\t\t\\setlength{\\oddsidemargin}{-69pt}\t\t\t\t\\begin{document}$$~D_{{D/H}} \\left( {{\\text{m}}^{2} /{\\text{s}}} \\right) = 1.2 \\cdot 10^{{ - 6}} \\exp \\left( {\\frac{{ - 131~{\\text{kJ}}/{\\text{mol}}}}{{R \\cdot T}}} \\right)$$\\end{document}Experiments with D2O/CO2 mixture of ratio 1:1 gave smaller exchange rates compared to pure D2O fluids, confirming that that not the pressure but the water fugacity leads to the increase in the mobility of hydrogen species. At 720 °C and pressures of 4–8 kbar, chemical diffusivities of H2O, tilde{D}_{{{text{H}}_{2} {text{O}}}}, were determined by fitting the weighted sum of the absorbances of the OH and the OD band vs. distance. The tilde{D}_{{{text{H}}_{2} {text{O}}}} values are similar to those reported by Kronenberg et al. (Geochim Cosmochim Acta 60:4075–4094, 1996) for dehydration of Kristallina adularia at ambient pressure. It is concluded that in both cases high concentrations of H2O molecules on interstitial sites govern the transport of hydrogen. Comparison of D/H interdiffusion to O diffusion in sanidine (Freer et al. in Phil Mag A75:485–503, 1997) implies that not only interstitial H2O but also protons contribute to the transport of hydrogen under hydrothermal conditions. On the other hand, the high DD/H at ambient pressure is attributed to an interdiffusion of protons and Na+, which is supported by Na tracerdiffusion data for sanidine (Wilangowski et al. in Defect Diffus Forum 363:79–84, 2015). A basic conclusion of this research is that hydrogen storage capacity and hydrogen diffusion in feldspars are largely determined by extrinsic defects, such as substitutional defects (i.e., Al3+ + H+ for Si4+) and associates of water molecules with vacancies. The bonding of hydrogen species to the defects can vary greatly, depending on the genesis of the feldspars, so that quantitative predictions are difficult.

Identifikasi Dampak Perkembangan Pariwisata terhadap Lingkungan di Desa Canggu, Kecamatan Kuta Utara, Kabupaten Badung


 
 
 The development of Canggu Village tourism began in the 1980s with tourists looking for waves at Canggu beach for surfing. This research aims to find out the impact of tourism development on environmental conditions in the village of Canggu North Kuta Badung Regency. In this case, it covers the environmental conditions of tourism in general, such as; attractions, facilities, infrastructure, transportation includes land and water.
 The research used qualitative method with observation and unstructured interviews. The primary data in this study is data sourced from direct to the research location by means of observation and. While the secondary data in this study is data obtained from other sources to complete the primary data obtained in the field. The informant determination technique used is a purposive technique, aimed at members of the public who know and are affected by the development of tourism in this village.
 The results showed that supporting infrastructure such as road access, sidewalks, parking lots as well as street lighting infrastructure (LPJ) in Canggu Village are still minimal, especially for roads, currently still quite narrow so that traffic jams often occur. The area of agricultural land in Canggu Village has decreased dramatically in the past five years, from 2010 to 2015 around 28 ha, due to the transfer of agricultural land functions into tourism accommodation and residential areas. Through the decline of agricultural land, affecting water conditions in Canggu Village, the number of villa businesses, restaurants, cafes, and laundry, most do not have good management of liquid waste reservoirs that pollute irrigation channels and rivers in Canggu Village. This not only resulted in damage to irrigation channels but also water pollution used by irrigation in agricultural land or rice fields. This situation has shifted the culture of farming and Subak activities in Canggu Village caused by the development of tourism in this village.
 Keyword: Identification, Impact of Tourism Development, Environment, Canggu
 
 

Withdrawal and dip coating of an object from a yield-stress reservoir

How much fluid adheres to an object pulled out from a liquid reservoir? We re-examine this dip-coating problem for yield-stress fluids. We propose a complete description that links the yield-stress fluid case with the Newtonian case. For extreme cases, asymptotic scaling laws are provided.

Self-preserving ice layers on CO2 clathrate particles: Implications for Enceladus, Pluto, and similar ocean worlds

Context. Gas hydrates can be stabilised outside their window of thermodynamic stability by the formation of an ice layer – a phenomenon termed self-preservation. This can lead to a positive buoyancy for clathrate particles containing CO2 that would otherwise sink in the oceans of Enceladus, Pluto, and similar oceanic worlds. Aims. Here we investigate the implications of Lifshitz forces and low occupancy surface regions on type I clathrate structures for their self-preservation through ice layer formation, presenting a plausible model based on multi-layer interactions through dispersion forces. Methods. We used optical data and theoretical models for the dielectric response for water, ice, and gas hydrates with a different occupancy. Taking this together with the thermodynamic Lifshitz free energy, we modelled the energy minima essential for the formation of ice layers at the interface between gas hydrate and liquid water. Results. We predict the growth of an ice layer between 0.01 and 0.2 μm thick on CO, CH4, and CO2 hydrate surfaces, depending on the presence of surface regions depleted in gas molecules. Effective hydrate particle density is estimated, delimiting a range of particle size and compositions that would be buoyant in different oceans. Over geological time, the deposition of floating hydrate particles could result in the accumulation of kilometre-thick gas hydrate layers above liquid water reservoirs and below the water ice crusts of their respective ocean worlds. On Enceladus, the destabilisation of near-surface hydrate deposits could lead to increased gas pressures that both drive plumes and entrain stabilised hydrate particles. Furthermore, on ocean worlds, such as Enceladus and particularly Pluto, the accumulation of thick CO2 or mixed gas hydrate deposits could insulate its ocean against freezing. In preventing freezing of liquid water reservoirs in ocean worlds, the presence of CO2-containing hydrate layers could enhance the habitability of ocean worlds in our Solar System and on the exoplanets and exomoons beyond.

Factors influencing transmission of tuberculosis in Ngeu Nata culture among Ngada community in Kupang, East Nusa Tenggara, Indonesia: Cross sectional study.

BackgroundEating “sirih/Betel” (Ngeu Nata) as a culture in Ngada society can become one of the primary source of Tuberculosis (TB) transmission due to share leaves and betel liquid reservoirs together with other people. If one of the people who share leaves is a TB patient, it can transmit TB to other person. The purpose of this study was to identify the factors that influence TB transmission in Ngeu Nata culture using the health belief model approach.Design and MethodsThis study used cross-sectional, involving 110 respondents, selected by consecutive sampling. The respondents were Bajawa ethnicity, age 36-67, at least consume Betel one a day together with other person in Ngada district, East Nusa Tenggara.ResultsThe results showed that most respondents had high transmission behavior in betel eating culture (51.8%). Factors related to TB transmission behavior: medical history of TB (p=0.028), knowledge about TB (p=0.038), the perceived of severity of TB (p=0.037); the perceived of benefits (p=0.039) and the perceived of barrier (p=0.038). The dominant factor was knowledge, (OR 2,365 (95% CI) 1,015-5,510).ConclusionsImplication: nurses should include aspect of Ngeu Nata cultural in designing TB education for Bajawa ethnicity in order to prevent TB transmission in Ngada district, East Nusa Tenggara.

Wicking in textiles at rates comparable to human sweating

To understand liquid transport mechanisms in textiles for thermal comfort, the textile field has developed standard test methods, such as vertical wicking or a droplet test. However, experience has shown that these tests can give contradictory results. Here we try to understand how liquid moves along capillary channels in textiles by simulating realistic human sweating generated from each sweat gland pore. The SWEAT test mimics realistic human sweating by supplying a continuous microfluidic flow to only a single yarn at a single point within the fabric substrate at a similar flow rate to a single sweat gland. We compare the results of typical test methods with either infinite liquid reservoirs or limited, but large amounts of liquid with those of a new test method, the SWEAT test. In the SWEAT test, we found transfer of liquid from one capillary channel to another occurred only at contact points between the yarns and not through the space between yarns. Additionally, we observed a wicking lengthtime superposition: liquid wicked within a single yarn initially, subsequently it spilled over to adjacent yarns, and the initial wicking rate in adjacent yarns was the same as the initial course yarn but with a time offset.

Interfacial supercooling and the precipitation of hydrohalite in frozen NaCl solutions as seen by X-ray absorption spectroscopy

Abstract. Laboratory experiments are presented on the phase change at the surface of sodium chloride–water mixtures at temperatures between 259 and 241 K. Chloride is a ubiquitous component of polar coastal surface snow. The chloride embedded in snow is involved in reactions that modify the chemical composition of snow as well as ultimately impact the budget of trace gases and the oxidative capacity of the overlying atmosphere. Multiphase reactions at the snow–air interface have been of particular interest in atmospheric science. Undoubtedly, chemical reactions proceed faster in liquids than in solids; but it is currently unclear when such phase changes occur at the interface of snow with air. In the experiments reported here, a high selectivity to the upper few nanometres of the frozen solution–air interface is achieved by using electron yield near-edge X-ray absorption fine-structure (NEXAFS) spectroscopy. We find that sodium chloride at the interface of frozen solutions, which mimic sea-salt deposits in snow, remains as supercooled liquid down to 241 K. At this temperature, hydrohalite exclusively precipitates and anhydrous sodium chloride is not detected. In this work, we present the first NEXAFS spectrum of hydrohalite. The hydrohalite is found to be stable while increasing the temperature towards the eutectic temperature of 252 K. Taken together, this study reveals no differences in the phase changes of sodium chloride at the interface as compared to the bulk. That sodium chloride remains liquid at the interface upon cooling down to 241 K, which spans the most common temperature range in Arctic marine environments, has consequences for interfacial chemistry involving chlorine as well as for any other reactant for which the sodium chloride provides a liquid reservoir at the interface of environmental snow. Implications for the role of surface snow in atmospheric chemistry are discussed.

Vapor-compression refrigeration system coupled with a thermochemical resorption energy storage unit for a refrigerated truck

Currently, refrigerated trucks adopt vapor-compression refrigeration systems for controlling the temperature of refrigerating compartment. This inevitably increases fuel consumption and exhaust emissions of engine. Although the solid sorption refrigerator can recover exhaust waste heat to generate cooling capacity, the low exhaust temperature at idle, often below 150 °C, significantly restricts its application in refrigerated trucks. To tackle these problems, a novel refrigeration system, including a vapor-compression subsystem and thermochemical resorption energy storage unit, using MnCl2/CaCl2-NH3 as the working pair, is proposed in this paper. To date, this is the first study wherein the system performance test is conducted on a refrigerated truck. Experimental results indicate that thermochemical energy storage can effectively recover waste heat of exhaust gas to store cold energy, and the refrigerating capacity during the discharging process is 2.2 kW at an evaporator outlet temperature of −15 °C. Moreover, cold energy can be released irrespective of whether the truck is parked or driven. Measurement of the liquid level in the liquid reservoir is an effective method for determining the point at which the operation switches between energy discharging and charging processes. At an ambient temperature of 30 °C and a refrigerating temperature of −20 °C, the energy efficiency of the novel system is 1.4, which is twice that of a conventional system. Furthermore, although energy storage increases initial investment of system, the payback period is estimated to be less than one year. In conclusion, the novel system effectively reduces transportation costs and satisfies the requirements of refrigerated trucks in a stable manner.

Development of Rapid and High-Precision Colorimetric Device for Organophosphorus Pesticide Detection Based on Microfluidic Mixer Chip.

The excessive pesticide residues in cereals, fruit and vegetables is a big threat to human health, and it is necessary to develop a portable, low-cost and high-precision pesticide residue detection scheme to replace the large-scale laboratory testing equipment for rapid detection of pesticide residues. In this study, a colorimetric device for rapid detection of organophosphorus pesticide residues with high precision based on a microfluidic mixer chip was proposed. The microchannel structure with high mixing efficiency was determined by fluid dynamics simulation, while the corresponding microfluidic mixer chip was designed. The microfluidic mixer chip was prepared by a self-developed liquid crystal display (LCD) mask photo-curing machine. The influence of printing parameters on the accuracy of the prepared chip was investigated. The light source with the optimal wavelength of the device was determined by absorption spectrum measurement, and the relationship between the liquid reservoir depth and detection limit was studied by experiments. The correspondence between pesticide concentration and induced voltage was derived. The minimum detection concentration of the device could reach 0.045 mg·L−1 and the average detection time was reduced to 60 s. The results provide a theoretical and experimental basis for portable and high-precision detection of pesticide residues.

SPIDER Cs Ovens functional tests

The SPIDER experiment is operating at the ITER Neutral Beam Test Facility PRIMA since June 2018 to study the operation of a full ITER-size negative ion source. In order to increase the negative ion extracted current and reduce the co-extracted electron current, caesium is evaporated inside the source. In fact, the adsorption of Cs onto the plasma grid, i.e. the first grid of the extraction system, lowers the surface work function, enhancing the probability of surface conversion of impinging hydrogen particles into negative ions. At the SPIDER test facility, Cs will be evaporated by heating a liquid Cs reservoir in three Cs ovens located at the back-plate of the ion source. The ovens must assure a controllable and reproducible evaporation. A SPIDER Cs oven prototype was procured and tested in the CAesium Test Stand (CATS) at PRIMA site to validate the design. Following the experimental tests, few improvements were introduced in the final design of the three Cs ovens for the SPIDER source. Then, the ovens were procured in 2019 and commissioned before their installation in SPIDER in 2020. This paper reports the functional tests of the SPIDER Cs ovens and of their embedded diagnostics. These tests were carried out at CATS, with the aim of characterizing the three ovens, in order to validate them for their use in SPIDER in the experimental campaign with caesium evaporation planned for the end of 2020. The ovens were successfully tested and characterized in terms of evaporation rate for different oven temperatures. Moreover, the three ovens show a good reproducibility and reliability.