Low Evaporation Rate Research Articles

Yield-Evaporation-Spill Relationship in Semiarid Reservoirs under Different Operating Rules

Semiarid regions are critical for water supply due to deficits in the water balance caused by low precipitation and high evaporation rates. This work studied 50 reservoirs in the Brazilian semiarid region, analyzing the impact of different operational rules on the volumetric reliability (VR) of reservoirs in meeting the demand in relation to the Yield-Evaporation-Spill (YES) effect. Adopting rules with higher rationing reduced overall VR, which varied according to the climatic period (i.e., wet or dry), but improved the reservoirs’ ability to meet human and animal water needs. Moreover, we verified the relationship between the morphohydric characteristics of the reservoirs and the YES relationship, including the relationship between these characteristics and the reservoirs’ ability to meet priority demands. In general, in many cases, large losses due to evaporation and spills were observed and may indicate inappropriate use of reserved resources due to climatic characteristics and improper operation of the reservoirs.

Impact of lateral groundwater flow on hydrothermal conditions of the active layer in a high-Arctic hillslope setting

Abstract. Modeling the physical state of permafrost landscapes is a crucial addition to field observations in order to understand the feedback mechanisms between permafrost and the atmosphere within a warming climate. A common hypothesis in permafrost modeling is that vertical heat conduction is most relevant to derive subsurface temperatures. While this approach is mostly applicable to flat landscapes with little topography, landscapes with more topography are subject to lateral flow processes as well. With our study, we contribute to the growing body of evidence that lateral surface and subsurface processes can have a significant impact on permafrost temperatures and active layer properties. We use a numerical model to simulate two idealized hillslopes (a steep and a medium case) with inclinations that can be found in Adventdalen, Svalbard, and compare them to a flat control case. We find that ground temperatures within the active layer uphill are generally warmer than downhill in both slopes (with a difference of up to ∼0.8 ∘C in the steep and ∼0.6 ∘C in the medium slope). Further, the slopes are found to be warmer in the uphill section and colder in the base of the slopes compared to the flat control case. As a result, maximum thaw depth increases by about 5 cm from the flat (0.98 m) to the medium (1.03 m) and the steep slope (1.03 m). Uphill warming on the slopes is explained by overall lower heat capacity, additional energy gain through infiltration, and lower evaporation rates due to drier conditions caused by subsurface runoff. The major governing process causing the cooling on the downslope side is heat loss to the atmosphere through evaporation in summer and enhanced heat loss in winter due to wetter conditions and resulting increased thermal conductivity. On a catchment scale, these results suggest that temperature distributions in sloped terrain can vary considerably compared to flat terrain, which might impact the response of subsurface hydrothermal conditions to ongoing climate change.

Interferometric measurement of co-operative evaporation in 2D droplet arrays

The evaporation dynamics of multiple droplet arrays is important in inkjet printing and spray coating, where co-operative “shielding” effects increase the overall evaporation time. However, current measurement methods provide limited information on how individual droplets contribute to the overall dynamics. In this work, we present a simple interferometric technique for precise measurements of droplet evaporation rates, which is not possible via traditional approaches. We validate the technique on a single droplet. We then extend our analysis to ordered and random 2D arrays of droplets. We demonstrate that the evaporation rate is highly dependent on the position of the droplet within the array and its confinement. The more confined droplets exhibit lower evaporation rates. Our results of ten different configurations and well over 100 droplets are in good quantitative agreement with a recent analytical model of co-operative evaporation rates. Our approach opens up possibilities for studies of collective evaporation effects, including in areas of current importance such as sneezes and exhaled breath.

Simulation of the impact of solar radiation intensity on the performance of economical solar water desalination still in Semnan province

Semnan province with a total area of 97000 km2 is the sixth biggest province in Iran. The evaporation rate in this province is high and can be. The index of the urban and rural water networks in this province is much higher than the global average, but according to the goals set for water supply to all people in all cities and villages, using new technologies is an effective way. High potential evaporation intensity in Semnan province, which reaches 1000-3000 (mm) per year, can be converted from a threat to an opportunity by using it as a new source of energy for a sustainable safe drinking water supply. In order to use of evaporation capacity, in this paper the impact of solar radiation intensity on the performance of single-slope solar still is investigated. The solar radiative flux depends on geographical location, season, and time. In this study, the dimension and temperature of the basin are constant and the effect of radiation intensity on water productivity of solar stills is investigated as a function of time, month (April) and location (Semnan province). The accuracy of the numerical method has been evaluated using different models and experimental data for the average Nusselt number on water surface and production rate of water. Results also indicate that the variation trends for radiation intensity are similar to the production rate. The maximum water production rate belongs to 12 o'clock with a 5.6% increase in comparison with 7:00 a.m., which has the lowest evaporation rate in the bell shaped curve.

Effect of continuous and modular floating covers on evaporation losses and microalgal growth

Evaporative losses from the water surface are substantial. Continuous floating covers strikingly suppress evaporation, but adversely affect the water environment. However, modular floating “elements” covers might overcome this issue, but with less evaporation suppression efficiency. We hypothesized that modifying the continuous floating covers by decreasing the coverage fraction (CF) could merge the advantages of both types. Two experiments were conducted to evaluate and compare the influence of modular and continuous floating covers on evaporation losses with emphasizing their impacts on the water environment by determining microalga growth as a bio-indicator. The effect of three modular floating covers, i.e., partially water-filled plastic potable bottles (W-PB), air-filled plastic potable bottles (A-PB), and styrofoam (STF)-disks on the evaporation rate was evaluated. In the second experiment, we investigated the influence of white spheres on evaporation rate in comparison to three continuous floating covers, i.e., styrofoam sheet (STF-sheet), white plastic sheet (WPS), and black plastic sheet (BPS), using three CF, i.e., 0.9, 0.95 and 1.0. The results revealed that modular floating covers decreased evaporation rate for the two months by 53.3, 44.6, 43.0% for STF-disks, W-PB, and A-PB, respectively. In the second experiment, the lowest evaporation rate was obtained using continuous floating covers at CF=1, in which all covers were acting equally, signifying the importance of CF over cover color. However, at CF=0.9, white spheres showed similar evaporation suppression efficiency to white continues floating covers, i.e., STF-sheet and WPS, but higher than the BPS, signifying the role of cover color over cover type when CF<1. Microalgae growth was positively affected by STF-disks and white spheres, and negatively by plastic potable bottles treatments. All continues floating covers at CF=1, inhibited microalgae growth, while at CF<1 continues floating covers boosted microalgae growth, except the BPS. In conclusion, the highest evaporation suppression (~95%) was obtained using continuous floating covers at CF=1, but with potential adverse impacts on the water environment. Modifying the continuous floating covers by decreasing the CF, increased water-saving, and enriched water ecology, relative to modular floating covers.

Sustainable MXene/PDA hydrogel with core-shell structure tailored for highly efficient solar evaporation and long-term desalination

Solar evaporation is an effective means to solve the scarce of fresh water resources. The developed solar evaporator has the disadvantages of low evaporation rate, poor mechanical performance, difficulty in long-term evaporation, and insufficient water purification capacity. Herein, we have developed a core-shell structure hydrogel solar evaporator taking MXene/PDA as the photothermal material. The hydrogel matrix possesses self-healing and remoldability, which is sustainable and in line with the theme of current material development. The prepared core-shell structure hydrogel showed excellent properties, with a compressive stress of 0.4 MPa and the evaporation rate is as high as 3.02 kg m−2 h−1, and the evaporation efficiency is 94.7 % under 1 sun illumination, which is better than most of the previously reported solar evaporators. Through the durability experiment in simulated seawater, the long-term desalination ability was verified. Simultaneously, the solar evaporator also exhibits various functions such as dye resistance, and heavy metal ion resistance. The core-shell structure solar evaporator shows great potential in long-term seawater desalination and water purification. Furthermore, it provides a promising strategy for the structural design of solar evaporators in the future.

Evaporation in Brazilian dryland reservoirs: Spatial variability and impact of riparian vegetation

Evaporation is a major factor controlling the hydrological dynamics of surface water reservoirs in dry environments, therefore quantification with minimal uncertainties is desired. The aim of this paper is to assess the spatial variability and impact of riparian vegetation on reservoir evaporation by remote sensing. Eight reservoirs located in subhumid and semi-arid climates in the Brazilian Drylands were studied. Scenes from Landsat 5 and Landsat 8 satellites (1985 and 2018) supplied the data for four evaporation models. For reference evaporation, the Class A Pan and Piché Evaporimeter closest to the reservoirs were considered. The occurrence/density of riparian vegetation was associated with the Normalized Difference Vegetation Index (NDVI) and its influence on evaporation was assessed. The Surface Energy Balance System for Water (AquaSEBS) model presented the best average performance (Nash-Sutcliffe Efficiency coefficient 0.40 ± 0.19). Evaporation was observed to be higher at the reservoirs' margins and near the dams, due to the contact of exposed soil and rock/concrete, respectively, which transfer heat to the water. Marginal areas near the riparian forest presented low evaporation rates with decreases between 18% and 31% in relation to the average. This interdependence was evidenced by the high negative correlation (R2 0.87–0.96) between NDVI and evaporation; vegetation reduces radiation because of the shading of the reservoir margin and changes local aerodynamics, reducing evaporation. Depending on the spatial variability of evaporation, it was found that the volumes transferred to the atmosphere may have variations of up to 30%. On average, the evaporated volume in all the studied reservoirs is 450,000 m3/day, a quantity enough to supply more than two million people. Overall, the results of this study contribute not only to a better understanding of the spatial variability of evaporation in surface reservoirs, but also of the interdependence between riparian vegetation and evaporation rates.

Rational Design of High‐Performance Bilayer Solar Evaporator by Using Waste Polyester‐Derived Porous Carbon‐Coated Wood

Wood‐based bilayer solar evaporators, which possess cooperative advantages of natural wood and photothermal conversion coating including fast water transportation, low heat conduction, renewability, and high light absorbability, hold great promise for water purification. However, previous studies suffer from low evaporation rates and high cost of coatings, and lack a deep understanding how the porous structures of coating layer function. Herein, a novel bilayer solar evaporator is designed through facile surface coating of wood by low‐cost porous carbon from controlled carbonization of polyester waste. The porous carbon bears rich oxygen‐containing groups, well‐controlled micro‐/meso‐/macropores, and high surface areas (1164 m2 g−1). It is proved that porous carbon improves sunlight absorption and promotes the formation of numerous water clusters to reduce water evaporation enthalpy. Owing to these combined features, the bilayer solar evaporator exhibits high evaporation rate (2.38 kg m−2 h−1), excellent long‐term stability, and good salt resistance. More importantly, a large‐scale solar desalination device for outdoor experiments is developed to produce freshwater from seawater. The daily freshwater production amount (3.65 kg m−2) per unit area meets the daily water consumption requirement of one adult. These findings will inspire new paradigms toward developing efficient solar steaming technologies for desalination to address global freshwater shortage.

Hsa_circ_0005915 promotes N,N-dimethylformamide-induced oxidative stress in HL-7702 cells through NRF2/ARE axis

N,N-dimethylformamide (DMF) is an organic compound widely used in industrial production processes as a solvent with a low evaporation rate. Excessive exposure to DMF may lead to liver damage. Oxidative stress has been reported as one of the main causes of DMF-induced hepatotoxicity. Several doses of DMF (0, 1, 5, and 10 mM) were used to treat HL-7702 cells for a relatively long period to simulate the actual exposure pattern in occupational settings, and oxidative stress was induced. Previous studies illustrated that circular RNA (circRNA) plays a vital role in sustaining hepatocyte physiological function. To explore whether aberrant circRNA expression is involved in DMF-induced excessive ROS generation and hepatotoxicity, high-throughput transcriptional sequencing was performed to identify the altered circRNA expression profiles in HL-7702 liver cells after treatment with 0, 75, or 150 mM DMF for 48 h. We found that levels of induced oxidative stress were similar to those in the long-term exposure model. Among the altered circRNAs, one circRNA (hsa_circ_0005915) was significantly upregulated after DMF exposure, and it affected DMF-mediated oxidative stress in HL-7702 cells. Further experiments revealed that hsa_circ_0005915 downregulated the expression of nuclear factor erythoid-2-related factor 2 (NRF2) at the post-transcriptional level via promoting the ubiquitination and degradation of NRF2, which led to the increase of ROS accumulation. Further investigation demonstrated that the expression levels of NRF2-regulated antioxidative genes—heme oxygenase 1 (HO1) and NAD(P)H quinone dehydrogenase 1 (NQO1)—indeed declined after the overexpression of hsa_circ_0005915. In vivo study also indicated that DMF exposure can upregulate the expression of mmu_circ_0007941 (homologous circRNA of hsa_circ_0005915) and downregulated Nrf2 and Ho1 proteins. In summary, our results revealed that hsa_circ_0005915 plays an important role in promoting DMF-induced oxidative stress by inhibiting the transcriptional activity of the NRF2/ARE axis, which provides a potential molecular mechanism of DMF-mediated hepatotoxicity.

Population dynamics for systems with cyclic predator–prey relations and pheromone dependent movement

Predator-prey dynamics is an important field of study to understand population dynamics in ecosystems. In nature, some predators use olfactory information, e.g., pheromone released by the prey, to locate their prey. Population dynamics is investigated in this paper for the case of three species with cyclic predator–prey relations and (artificial) pheromone on a one-dimensional lattice. Using computer simulations we study a three-species model for different pheromone evaporation rates. The results reveal that the survival of three species depends on the evaporation rate. At a sufficiently low evaporation rate and high densities, a phase transition takes place. Before the phase transition, three species coexist at the same time. After the phase transition, however, two species are extinct and only one species survives. For a sufficiently high value of evaporation rate, there does not happen a phase transition and three species coexist at all densities. The critical density at which phase transition takes place depends on the value of the evaporation rate.

Assembling carbon dots on vertically aligned acetate fibers as ideal salt-rejecting evaporators for solar water purification

• An anti-salt-fouling solar evaporator is developed for continuous water purification. • This evaporator is constructed by carbon dots and vertically aligned acetate fibers. • Evaporation rate of high-salinity seawater reaches to 2.6 kg m −2 h −1 under one sun. • Total materials cost of the presented evaporator is $15.01 m −2 . A low-cost and anti-salt-fouling system to perform solar interfacial water purification in long-term stability is considered to be a promising ways to solve freshwater scarcity crisis globally. However, the present self-regenerating solar evaporators are still confronted with challenges in terms of the relatively low evaporation rate, unsatisfactory solar-to-vapor efficiency, intricate or costly preparation steps. Herein, we present a novel and controllable system established by assembling carbon dots (CDs) on vertically aligned acetate fibers (VAAFs) with very low thermal conductivity and excellent water transport capacity. As-prepared VAAFs@CDs-T can spontaneously reject salt accumulation through rapid fluid convection within the evaporating interfaces and simultaneously sustain efficient heat localization. Thus, it not only possesses superior salt-rejection capability in long-term operation, but also enables considerably high water evaporation rate at 2.6 kg m −2 h −1 with 93.9% solar-to-steam efficiency under one sun even treating with 20 wt% salt solution and industrial wastewater. Total materials cost of this system is merely $15.01 m −2 , outperforming most previous solar evaporators in the cost-effectiveness. Moreover, CDs can be replaced with other zero-dimensional materials and hereby achieving further enhanced evaporation efficiency is hopeful for this system.

Understanding and modelling future wind-driven rain loads on building envelopes for Canada

Wind-driven rain (WDR) is the amount of rainfall that passes through a vertical plane due to its co-occurrence with wind, which can adversely impact the performance of building façades. Hygrothermal and durability analysis of façades require quantification of future WDR loads for a changing climate. This study evaluates projected changes to WDR loads across Canada for the end of century using regional climate model simulations for the Representative Concentration Pathway scenario 8.5. WDR loads are quantified in terms of omnidirectional and directional WDR amounts over periods of interest, which are relative indicators of WDR exposure and potential moisture content of absorbent surfaces, respectively. Furthermore, return levels of annual maximum WDR spell amounts, which are representative of the risk penetration through the façade, are also used to develop WDR risk category maps for Canada and specifically for 16 Canadian cities.Future projections suggest increases in WDR loads for Arctic Canada, due to increases in both rainfall and wind magnitudes, while for other regions with increased loads, it is mostly due to increases in rainfall. Results suggest a shift in the timing of the highest monthly WDR loads from summer to fall, which is suggestive of higher WDR penetration through wall systems, given the relatively low evaporation rate in fall compared to summer even in a warmer climate. Furthermore, the developed WDR risk category maps show changes to critical façade orientations with elevated risk in future climate. This information is crucial in the development of detailed guidelines to ensure climate-resilient buildings.

Designing Carbonized Loofah Sponge Architectures with Plasmonic Cu Nanoparticles Encapsulated in Graphitic Layers for Highly Efficient Solar Vapor Generation.

Solar vapor generation represents a promising approach to alleviate water shortage for producing fresh water from undrinkable water resources. Although Cu-based plasmonics have attracted tremendous interest due to efficient light-to-heat conversion, their application faces great challenges in the oxidation resistance of Cu and low evaporation rate. Herein, a hybrid of three-dimensional carbonized loofah sponges and graphene layers encapsulated Cu nanoparticles is successfully synthesized via a facile pyrolysis method. In addition to effective light harvesting, the localized heating effect of stabilized Cu nanoparticles remarkably elevated the surface temperature of Cu@C/CLS to 72 °C, and a vapor generation rate as high as 1.54 kg m-2 h-1 with solar thermal efficiency reaching 90.2% under 1 Sun illumination was achieved. A study in the purification of sewage and muddy water with Cu@C/CLS demonstrates a promising perspective in a practical application. These results may offer a new inspiration for the design of efficient nonprecious Cu-based photothermal materials.

Geoeconomic interest of minerals assemblage of sebkha El Melah, southeastern Tunisia

AbstractThis work aimed to study the formation of salt through a progressive evaporation of sebkha El Melah brine. The precipitated salt in the case of sebkha El Melah is variable along the progressive evaporation. Weights of salt after each phase of precipitation indicate a heterogeneous evaporation process cumulating at 315 g L−1. With an increasing evaporation of El Melah brine, the number of precipitated mineral species increased. The cumulative number of species along the evaporation process reached 20, including principally: Halite (NaCl) (73–95%), epsomite (MgSO4·7H2O) (7–14%), bischofite (MgCl2:6H2O) (1%), Kieserite Mg(SO4)(H2O) (0–2%), magnesite (MgCO3) (1–4%), polyhalite (K2Ca2Mg(SO4)4,2H2O). Also, the thermodynamic theoretical modeling of the El Melah brine shows convergence with geochemical and mineralogical experimental data. At an evaporation rate of 60%, the sebkha of El Melah annually provides with 315,000 tons of salt. The majority of salt (80%) is halite. The remaining 20% contains different species having a huge economic interest. From an industrial viewpoint, our study shows that the purity of halite is guaranteed at low rates of evaporation. Evaporation between 50 and 75% produces a mixture dominated by halite. Evaporation higher than 75% needs further studies to find the mineralogical composition and the phase of each mineral precipitation. The saline system of El Melah represents a geoeconomic interest due to the cheap natural process of production, its large quantity of halite with varieties of other accessory minerals, and cheap procedure of exportation.

Highly salt-resistant and all-weather solar-driven interfacial evaporators with photothermal and electrothermal effects based on Janus graphene@silicone sponges

Abstract Solar-driven interfacial evaporators are very promising for obtaining clean water, but suffer from serious performance degradation due to salt-fouling, low evaporation rate under weak illumination and low clean water collection rate. Here, we report highly salt-resistant and all-weather evaporators with photothermal and electrothermal effects based on the Janus graphene@silicone sponges with opposing wettability. The evaporators achieve a remarkable high evaporation rate of 6.53 kg m−2 h−1 for 3.5 wt% NaCl solution under 1 sun illumination with a 5 V solar cell as compensation owing to their high solar absorption, low thermal conductivity, unique Janus structure and synergetic photothermal and electrothermal effects. Even in gloomy and dark environments, the evaporators could still generate vapor (1.51 kg m−2 h−1). Moreover, the evaporators feature long-term excellent salt-resistance, e.g., > 10 d continuous evaporation in 10 wt% NaCl solution without performance degradation and salt precipitation, because of ultrafast water supply and salt diffusion in the macroporous superhydrophilic shell. Furthermore, the evaporators show high clean water collection rates of 21.92 kg m−2 d−1 (1 sun-9 h/0 sun-15 h + 5 V, indoor) and 9.65 kg m−2 d−1 (natural sun light + 5 V, outdoor). This study offers a new approach for efficiently obtaining clean water via solar desalination.

Simple and Continuous Fabrication of Janus Liquid Marbles with Tunable Particle Coverage Based on Controlled Droplet Impact

Liquid marbles are gaining increased attention because of their added advantages such as low evaporation rates, less friction, and ease of manipulation over the pristine liquid drop. Their functionalities could be further enhanced by incorporating different types of particles (size, hydrophobicity, chemical properties, etc.), commonly called Janus liquid marbles (JLMs). However, their fabrication process remains a challenge, especially when we require continuous production. Here, we present a simple and fast approach for the fabrication of JLMs covered with nano- and microparticles in an additive-free environment based on the controlled impact of a water drop over the particle beds. The fabrication process involves collection of polyvinylidene difluoride particles (PVDF, particle type 1) by a water drop followed by its impact over an uncompressed bed of black toner particles (BTP, particle type 2). The whole process takes a time of approximately 30 ms only. The drop impact and the condition of the JLM formation were explained based on the Weber number (We) and maximum spread (βm) analysis. A theoretical model based on the energy balance analysis is performed to calculate the maximum spreading (βm), and the experimental and theoretical analyses are found to be in good agreement. Tunability in particle coverage is demonstrated by varying the droplet volume in the range of 5-15 μL. We further extend this strategy for the fast and continuous production of nearly identical JLMs, which could enhance the capabilities of open-surface microfluidic applications.

Razlike u mikoflori na ovitcima trajnih fermentiranih kobasica prije i šest mjeseci nakon skladištenja u hladnjaku

During the curing period of dry-fermented sausages, the surface mycoflora changes according to the environmental conditions and intrinsic factors, such as nutrient content, water activity, pH value and the presence of antimicrobial substances (starter cultures). In this study, 25 samples of dry-fermented sausages from Croatian family small holdings were examined, the casings peeled off and examined for mycobiota before and after six months of refrigerated storage in plastic bags, at +4 °C in darkness, at a low humidity and evaporation rate. For mycobiota identification, traditional (macroscopic and microscopic) and molecular (Polymerase Chain Reaction, PCR) methods were combined. At the beginning of the study (after sausage curing), the prevalent isolated species were from the genera Penicillium (74%), Aspergillus 14% and Mucor (12%). After the six month period, a different mould structure was observed, with the dominant isolation of Aspergillus genus (64%), followed by the genera Penicillium (34%) and Mucor (2%). In comparison with the literature data, it can be concluded that the casing mycoflora on dry-fermented sausages stored in the refrigerator changed in the same way as if they not been refrigerated, though the process of mycoflora change was slower with refrigeration.

Near-field spray characterization of a spill return atomizer using a PIV laser sheet

The Combustion of liquid fuels is largely dependent on effective ways of atomization. The investigation of flow dynamics and atomization of alternative fuels is essential and supportive for combustion assessment. The current experimental investigation aims at providing a microscopic insight into the spray characteristics of the conventional (light diesel oil) fuel, a renewable fuel (waste cooking oil), and their blend together. A PIV laser measuring technique is used to provide detailed information on the fuel spray: droplets size, pattern, evaporation rate, instantaneous velocity, local cone angle, average axial velocity, penetration, and vorticity. The experiments cover four air to liquid ratios (ALR) of 0.8, 0.78, 0.65, and 0.57. A coaxial spill return atomizer is employed downwards as well as is surrounded by co-flowing air (kg/hr) of 48, 52.2, 55.8, and 60. The spray images are taken in an open atmosphere and the assessment of the fuel droplets velocity and size is obtained through PIV cross-correlation inside a glass room. The maximum evaporation rate is 48.1% for diesel fuel, 37% for waste cooking oil, and 44% for blended fuel at an ALR of 0.57. The application of co-flowing air (kg/hr) of 48 will reduce the local cone angle by 17%, 6%, and 4.3%. The interaction between waste cooking oil droplets with surrounding air is very difficult because of its high viscosity, density, lower evaporation rate, and larger droplets size than diesel fuel.

Effect of Core Liquid Surface Tension on the Liquid Marble Shell

AbstractLiquid marble is a non‐wetting droplet coated with micro‐ or nanometer sized particles and exhibits great versatility as a standalone system. Unique features such as low evaporation rate, low friction, and a porous shell enable it to be a potential tool for gas sensing, cell culture, and drug delivery. With the growing number of interests in these fields, it is important to understand the structure of the liquid marble shell and how it behaves with the variation of the surface tension of the core liquid. This paper investigates the thickness and the mass of liquid marble shell at various surface tension values. Surfactant mediated surface tension reduction allows the encapsulating particles to penetrate more into the core liquid and decreases the shell thickness. The shell thickness decreases significantly with the surface tension, whereas the mass remains almost constant. Interestingly, the trend reverses with further decrease of the surface tension. In this regime, both the thickness and the mass of the shell increase due to interfacial jamming. This work provides a new insight into understanding the contribution of the particle distribution at the shell for the stability and the measurement of the effective surface tension of a liquid marble.

Role of the urban plant environment in the sustainable protection of an ancient city wall

Cultural heritage sites are exposed to urban environmental phenomena and various forms of deterioration that degrade their historical and cultural value. As an important element, plant landscaping can be a potential regulator of the microenvironment, mitigating the adverse effect of the local climate to cultural heritage. The influence of evergreen trees on the weathering deterioration of the Nanjing City Wall was studied and evaluated through field measurements and numerical modeling. A two-dimensional hygrothermal ‘City Wall–plant’ model was developed to simulate the shaded and unshaded surfaces. The results showed that compared to the unshaded case, the shaded surface showed smaller temperature fluctuations with an increase in the minimum temperature by 0.5°C – 0.8 °C, smaller water content fluctuations with the standard deviation decreasing by 0.017 kg/kg at the height of 0.15 m, and a lower evaporation rate by 8 – 18%. This means that evergreen trees can effectively reduce the risk of deterioration on wall surfaces due to freeze–thaw cycles, efflorescence, and subflorescence. These findings provide the theoretical basis for the sustainable preservation of sites with cultural heritage.