Low Humidity Environment Research Articles

Composite porous 3D foam for solar-driven atmospheric water harvesting in low humidity natural environment

Solar-driven atmospheric water harvesting (SAWH) has been recognized as a promising strategy to alleviate the freshwater crisis. Herein, we developed an efficient porous polymeric foam, LiCl@CCP-PPy, which has low preparation cost, strong adaptability and portability, and is very suitable for use as a wicking material in SAWH systems. LiCl@CCP-PPy contains abundant –NH2 and –OH groups. These hydrophilic groups and excellent pore structure (porosity is 80.22 %) make it have a good moisture absorption effect even in low humidity environment. The moisture absorption capacity can reach 2.86 g/g at 35 % RH and 25 °C, and 4.48 g/g at 25 °C and 90 % RH. The saturated water absorption effect was 27.48 g/g. LiCl@CCP-PPy can be scaled up for production. In addition, LiCl@CCP-PPy has a high light absorption rate of more than 90 %, and the strong photothermal conversion ability of Polypyrene (PPy) enables the material to warm up rapidly under natural light, thereby accelerating the desorption process (96 % desorption rate at 1 kW/m2 for 3 h). Based on the above properties, LiCl@CCP-PPy was applied to the Tengger desert in northwest China. The final water production efficiency was 0.64 L/m2/d, and the collected water quality met the international drinking water standard.

Moisture-driven energy generation by vertically structured polymer aerogel on water-collecting gel

In the realm of energy harvesting, free-standing, film-type, moisture-driven electricity generators (MEGs) based on polymer hydrogels with moisture-retaining capability are promising as a convenient and practical power source, making them potentially suitable for various self-powered, wearable, and patchable electronic devices. Their performance is, however, substantially degraded under low-humidity (<40%) conditions owing to the limited water supply to the device. This study presents a high-performance film-type MEG that functions at a low humidity of 20%. The MEG is based on an ion-selective polymer aerogel as an electricity-generating layer, constructed on a water-collecting gel as a water reservoir. The water-collecting gel in the bi-layered MEG absorbs moisture even under low-humidity conditions and efficiently delivers moisture to the electricity-generating aerogel layer. The energy-harvesting ability of the electricity-generating aerogel layer is further facilitated by its characteristic vertical microstructure, which comprises aerogel pores directionally grown on the frozen water-collecting gel during the freeze-drying process. The low humidity-tolerant MEG generated a stable open-circuit voltage of 1.1 V for more than 500 min even under dry conditions (20% relative humidity). Various self-powered electronic applications are demonstrated with the low-humidity-tolerant, bi-layered MEGs in dry environments. This study provides new insights for designing future MEGs for operation in low-humidity environments, further facilitating the development of green and sustainable power generation.

Proton exchange membranes with functionalized sulfonimide and phosphonic acid groups for next-generation fuel cells operating at 120 °C

Proton exchange membrane fuel cells (PEMFCs) face a significant challenge when operating in high-temperature and low-humidity environments, the hydrocarbon-based polymers that are sulfonated or phosphonated can’t meet the demand for achieving high performance. Modifying perfluorosulfonyl fluoride (PFSF) through meticulous design of side-chain chemical structures and introducing functionalized sulfonimide and phosphonic acid groups. Membranes derived from a perfluorocarbon backbone and polyacid side chain structures exhibit distinct microphase separation. The sulfonimide group exhibits hyper-acidic properties, whereas the phosphonic acid group functions as proton acceptor and donor. These two groups work synergistically to establish a distinct proton transport channel. The robust adsorption between acidic functional groups and water molecules enhances the diffusion of water molecules, resulting in an increase in proton conductivity. Moreover, Density Functional Theory (DFT) calculations reveal that the phosphonic acid group of the side chain has difficulty forming anhydrides. The prepared perfluorosulfonimide-phosphonic acid (PFSNPA) proton exchange membrane demonstrates an impressive conductivity of 263 mS·cm−1 at 120 °C. In H2/Air fuel cell tests, PFSNPA achieves an outstanding output power of 1076.1 mW·cm−2 at 120 °C and 40 % RH. This study introduces a new approach for designing and fabricating proton exchange membrane materials for high-temperature fuel cells.

Ocular effects of exposure to low-humidity environment with contact lens wear: A pilot study.

To compare the ocular effects of exposure to a low-humidity environment with and without contact lens (CL) wear using various non-invasive tests. Fourteen habitual soft CL wearers were exposed to controlled low humidity (5% relative humidity [RH]) in an environmental chamber for 90 min on two separate occasions. First, when wearing their habitual spectacles and then, on a separate visit, when wearing silicone hydrogel CLs that were fitted specifically for this purpose. All participants had adapted to the new CL prior to data collection. Three non-invasive objective measurements were taken at each visit: blinking rate, objective ocular scatter (measured using the objective scatter index) and ocular surface cooling rate (measured using a long-wave infrared thermal camera). At each visit, measurements were taken before the exposure in comfortable environmental conditions (RH: 45%), and after exposure to environmental stress (low humidity, RH: 5%). CL wearers showed increased blinking rate (p < 0.005) and ocular scatter (p = 0.03) but similar cooling rate of the ocular surface (p = 0.08) when compared with spectacle wear in comfortable environmental conditions. The exposure to low humidity increased the blinking rate significantly with both types of corrections (p = 0.01). Interestingly, ocular scatter (p = 0.96) and cooling rate (p = 0.73) were not significantly different before and after exposure to low humidity. There were no significant two-way interactions between correction and exposure in any of the measurements. CLs significantly increased the blinking rate, which prevented a quick degradation of the tear film integrity as it was refreshed more regularly. It is hypothesised that the increased blinking rate in CL wearers aids in maintaining ocular scatter quality and cooling rate when exposed to a low-humidity environment. These results highlight the importance of blinking in maintaining tear film stability.

In Vitro and In Vivo Testing of Microbe Growth on Antimicrobial Nursing Scrubs.

Around 5% to 10% of hospitalized patients develop a hospital-acquired infection (HAI). Scrubs are a potential vector of HAIs. To compare the antimicrobial characteristics of scrubs with and without an antimicrobial fabric coating, as tested in the laboratory (in vitro) and hospital (in vivo) environments. Two protocols were conducted to address the purpose. The in vitro protocol was a laboratory study that involved observing the microbe growth after inoculating coated and uncoated scrub fabric swatches with S. aureus and then processing them in moist and dry environments. The in vivo protocol was a clinical trial that measured microbe growth on coated and uncoated scrubs prior to and following nursing staff completing a 12-hr shift on an acute care unit, as measured by colony forming units (CFUs). For high-humidity environments, the in vitro study indicated that swatches treated with an antimicrobial coating exhibited minimal microbe growth, while untreated swatches exhibited significant microbe growth. For low-humidity environments, coated and uncoated swatches were all found to exhibit minimal microbe growth. In the in vivo study, the CFUs increased on scrubs worn by nurses over a 12-hr shift with no significant difference in CFUs for coated and uncoated scrubs. For bacteria in a warm and moist environment, the antimicrobial coating was found to be important for inhibiting growth. For bacteria in a warm and dry environment, both coated and uncoated fabrics performed similarly as measured at 24 hr, with minimal bacterial growth observed. In a hospital environment, microbe growth was observed, but no significant difference was detected when comparing coated and uncoated scrubs. This may have been due to the short time between exposure and culturing the scrubs for analysis immediately at the end of the shift not allowing for enough time to kill or inhibit growth. Contact time between the bacteria and scrub fabric (coated or uncoated) in the in vivo study more directly correlated with the 0-hr observations for the in vitro study, suggesting that the ineffectiveness of the treated scrubs in the clinical results may be due in part to short residence times before collection.

Single cell analysis of short-term dry eye induced changes in cornea immune cell populations.

Dry eye causes corneal inflammation, epitheliopathy and sensorineural changes. This study evaluates the hypothesis that dry eye alters the percentages and transcriptional profiles of immune cell populations in the cornea. Desiccating stress (DS) induced dry eye was created by pharmacologic suppression of tear secretion and exposure to drafty low humidity environment. Expression profiling of corneal immune cells was performed by single-cell RNA sequencing (scRNA-seq). Cell differentiation trajectories and cell fate were modeled through RNA velocity analysis. Confocal microscopy was used to immunodetect corneal immune cells. Irritation response to topical neurostimulants was assessed. Twelve corneal immune cell populations based on their transcriptional profiles were identified at baseline and consist of monocytes, resident (rMP) and MMP12/13 high macrophages, dendritic cells (cDC2), neutrophils, mast cells, pre T/B cells, and innate (γDT, ILC2, NK) and conventional T and B lymphocytes. T cells and resident macrophages (rMP) were the largest populations in the normal cornea comprising 18.6 and 18.2 percent, respectively. rMP increased to 55.2% of cells after 5 days of DS. Significant changes in expression of 1,365 genes (adj p < 0.0001) were noted in rMP with increases in cytokines and chemokines (Tnf, Cxcl1, Ccl12, Il1rn), inflammatory markers (Vcam, Adam17, Junb), the TAM receptor (Mertk), and decreases in complement and MHCII genes. A differentiation trajectory from monocytes to terminal state rMP was found. Phagocytosis, C-type lectin receptor signaling, NF-kappa B signaling and Toll-like receptor signaling were among the pathways with enhanced activity in these cells. The percentage of MRC1+ rMPs increased in the cornea and they were observed in the basal epithelium adjacent to epithelial nerve plexus. Concentration of the chemokine CXCL1 increased in the cornea and it heightened irritation/pain responses to topically applied hypertonic saline. These findings indicate that DS recruits monocytes that differentiate to macrophages with increased expression of inflammation associated genes. The proximity of these macrophages to cornea nerves and their expression of neurosensitizers suggests they contribute to the corneal sensorineural changes in dry eye.

Freezing Delay of a Drop Impacting on a Monolayer of Cold Grains.

We investigate a subfreezing droplet impact scenario in a low-humidity environment, where the target is a cold granular monolayer. When the undercooling degree of targets passes a threshold, such a granular layer effectively postpones the bulk freezing time of the droplet in comparison with the impact on the bare substrate underneath. In this case, the retraction of the droplet after impact reduces the contact area with the cold substrate, even though both the grains and the substrate are wettable to the liquid. We find that the significant changes in the dynamic behavior are triggered by freezing the liquid that wets the pores. Owing to the small dimension of the pores, the freezing process is rapid enough to match the dynamics over the droplet dimension. In certain circumstances, the rapid freezing may even stop liquid penetration and shed icing from the surface underneath.

Experiment for the performance of a thin membrane inclined automatic wicking dew-point evaporative cooling device based on simulation results

The traditional indirect evaporative coolers necessitate a continuous operation of water pumps to ensure the wetting of wet channel walls. However, excessive water spraying can lead to a thickened water film, negatively impacting heat transfer efficiency and generating an additional pressure drop. Identifying suitable water supply strategies and exploring materials for the wet channel that possess good moisture retention and evaporation characteristics has drawn research attention over the years.In this study, an automatic wicking dew-point evaporative cooling device, whose structure was determined by corresponding optimal performance simulation research, was designed and manufactured. The thin film exhibits a certain inclination angle between the dry and wet channels to form a triangular channel to enhance support and increase heat transfer area. Utilizing the automatic water absorption characteristics of the membrane for water supply instead of spraying, makes the water more uniform and heat exchange more efficient. A comprehensive study was conducted on the effects of different operating parameters (working-to-intake air ratio, intake air velocity, water temperature, intake air temperature, and intake air humidity) on the performance of the device. The results indicate that the cooler performs best in high-temperature, low-humidity environments. When the inlet temperature, humidity, and velocity are within the range of 25–45 °C, 20–80 %, and 0.5–2.5 m/s, respectively, with a water temperature of 22 °C and an air-to-water flow rate ratio of 0.5, the maximum temperature drop can reach 14.8 °C, and the cooling capacity per unit area ranges from 13 to 150 W/m2. The wet-bulb efficiency and dew-point efficiency increased from 52.4 % and 33.6 % to 110.6 % and 88.5 %, respectively. When the air velocity increases from 0.5 m/s to 2.5 m/s, the product air temperature increases by 3.1 °C, and the wet-bulb efficiency and dew-point efficiency decrease by 25.1 % and 17.5 %, respectively. However, the variation trends of unit area cooling capacity and energy efficiency ratio (EER) are opposite. The optimal operating conditions are proposed with an air volume ratio of 0.5 and a water temperature range of 22–26 °C. Finally, the temperatures of the product air and water were observed during long-term operation testing to evaluate the stability of the device.

Silver Nanowire Networks with Moisture-Enhanced Learning Ability.

The human brain possesses a remarkable ability to memorize information with the assistance of a specific external environment. Therefore, mimicking the human brain's environment-enhanced learning abilities in artificial electronic devices is essential but remains a considerable challenge. Here, a network of Ag nanowires with a moisture-enhanced learning ability, which can mimic long-term potentiation (LTP) synaptic plasticity at an ultralow operating voltage as low as 0.01 V, is presented. To realize a moisture-enhanced learning ability and to adjust the aggregations of Ag ions, we introduced a thin polyvinylpyrrolidone (PVP) coating layer with moisture-sensitive properties to the surfaces of the Ag nanowires of Ag ions. That Ag nanowire network was shown to exhibit, in response to the humidity of its operating environment, different learning speeds during the LTP process. In high-humidity environments, the synaptic plasticity was significantly strengthened with a higher learning speed compared with that in relatively low-humidity environments. Based on experimental and simulation results, we attribute this enhancement to the higher electric mobility of the Ag ions in the water-absorbed PVP layer. Finally, we demonstrated by simulation that the moisture-enhanced synaptic plasticity enabled the device to adjust connection weights and delivery modes based on various input patterns. The recognition rate of a handwritten data set reached 94.5% with fewer epochs in a high-humidity environment. This work shows the feasibility of building our electronic device to achieve artificial adaptive learning abilities.

Aggregation and Charging of Mineral Cloud Particles under High-energy Irradiation

It is known from Earth that ionizing high-energy radiation can lead to ion-induced nucleation of cloud condensation nuclei in the atmosphere. Since the amount of high-energy radiation can vary greatly based on the radiative environment of a host star, understanding the effect of high-energy radiation on cloud particles is critical to understand exoplanet atmospheres. This study aims to explore how high-energy radiation affects the aggregation and charging of mineral cloud particles. We present experiments conducted in an atmosphere chamber on mineral SiO2 particles with diameters of 50 nm. The particles were exposed to gamma radiation in either low-humidity (RH ≈ 20%) or high-humidity (RH > 50%) environments. The aggregation and charging state of the particles were studied with a scanning mobility particle sizer. We find that the single SiO2 particles (N1) cluster to form larger aggregates (N2–N4), and that this aggregation is inhibited by gamma radiation. We find that gamma radiation shifts the charging of the particles to become more negative by increasing the charging state of negatively charged particles. Through an independent t-test, we find that this increase is statistically significant within a 5% significance level for all aggregates in the high-humidity environment and all except the N1 particles in the low-humidity environment. For the positively charged particles, the changes in charging state are not within the 5% significance level. We suggest that the overall effect of gamma radiation could favor the formation of a high number of small particles over a lower number of larger particles.

The influence of different clay/sand ratios on the hygrothermal properties of earthen plasters in the Maijishan Grottoes

Variations in temperature and moisture content in the earthen plasters of the Maijishan Grottoes can readily lead to mural deterioration. This study investigates the influence of two different clay/sand ratios on the hygrothermal properties of earthen plasters in the Maijishan Grottoes. Two distinct types of earthen plasters samples were created with different clay/sand ratios: one with a weight ratio of 30:70 and another with a weight ratio of 70:30. The hygrothermal properties of earthen plasters samples were examined, and the temperature and moisture content variations were evaluated based on measurement data of hygrothermal environment in three caves. The findings revealed that the influence of the clay/sand ratios on thermal properties was relatively minor compared to its effect on hygric properties. Lower clay/sand ratio resulted in decreased thermal conductivity and specific heat capacity of earthen plasters, leading to increased temperature fluctuation, but the difference is minor. Additionally, in high-humidity environments, the difference in moisture content variations between the two types is greater than in low-humidity environments as the relative humidity changes. This research holds significant implications for the preservation of murals in the Maijishan Grottoes while also providing fresh perspectives for the restoration of multi-layered mural structures.

Electrospinning-assisted construction of rapid proton conduction channels in halloysite nanotube-encapsulated ionic liquid-embedded sulfonated poly(ether ether ketone) proton exchange membranes

The most fatal drawback of traditional sulfonated polymer proton-exchange membranes (PEMs) is their heavy dependence on water molecules to conduct protons, which causes a sharp decrease in their proton conductivity in low-humidity environments. Here, composite membranes were fabricated by electrostatically spinning halloysite nanotube-encapsulated ionic-liquids (IL@HNTs) incorporated into sulfonated poly(ether ether ketone) (SPEEK) (SPEEK/IL@HNTs). Using electrospinning, one-dimensional IL@HNTs ionogels with good water absorption were axially and uniformly aligned along the fiber filament direction. This formed long-range uninterrupted proton conduction pathways that greatly improved the proton conductivity of the composite membrane under various humidity environments. The axially-aligned structure facilitated crystallization, which improved the mechanical properties and thermal stability of the composite membrane. The SPEEK/6IL@HNTs membrane exhibited a through-plane proton conductivity of 139.2 mS cm−1 at 90 °C/98 % RH, representing a significant increase compared with the intrinsic SPEEK membrane. The SPEEK/6IL@HNTs membrane demonstrated a maximum power density of 732 mW cm−2, which exceeded that of the Nafion115 membrane (328 mW cm−2) by a factor of 2.2. It exhibited a single-cell performance equivalent to that of the Nafion212 membrane (723 mW cm−2), demonstrating that this provides a feasible approach to operating fuel cells in low-humidity environments without additional humidification.

Air oxidation of carbon supports boosts the low-humidity fuel cell performance.

We introduce a straightforward, yet effective strategy to combat the performance decline of proton-exchange membrane fuel cells in low-humidity environments. Our method centers on air-oxidizing carbon supports, significantly improving proton and oxygen transport within the cathode catalyst layer.

Water, Feeding Efficiencies, and Development of Dermestes maculatus DeGeer (1774)

Although dermestids have varying ecological roles, most Dermestes are generally associated with decomposition of dry animal tissues. However, Dermestes maculatus DeGeer (1774) can eat soft, hydrated tissues, so it is unclear if the apparent preference of Dermestes maculatus for dry tissue reflects physiological adaptation or competitive exclusion by blowflies and other invertebrate scavengers that arrive at carrion earlier and may have faster immature development rates. To address this question, we examined development of D. maculatus larvae on hydrated and dry food, and we determined development rates at a constant temperature of 25°C. Specifically, we conducted multiple replicated experiments in incubators. Initial experiments used with a factorial treatment arrangement of food type (wet versus dry) and larval density (1, 5, 10, 15, and 25 per 5 g of food) with 4 replications. Additionally, for dry food we determined growth, consumption, and conversion rates for 3-6 stage larvae, and consumption and conversion rates for adults. Hydrated food significantly reduced survivorship of D. maculatus larvae and adults (ca. 20% survivorship) as compared to dried food with survivorship rates of ca. 80-90%. Adults feeding on hydrated food were observed to void water, likely to overcome problems with osmotic regulation. Given dry food with little water and high conversion rates (much greater than 10%) in larvae, evidence indicated D. maculatus obtains most water metabolically and not through diet. These adaptations indicate that D. maculatus (and likely related species) have evolved physiologically to exploit dry carrion thereby avoiding competition with other carrion-feeding species. However, D. maculatus is not adapted for low humidity environments or to avoid extreme water loss, these adaptations allow use of a unique resource but do not represent adaption to xeric conditions generally. Moreover, the very adaptations that allow D. maculatus to survive on dry food, are potentially lethal when only hydrated food is available.

Effect of humidity on postmortem changes in rats.

In veterinary forensic science, accurately determining the postmortem interval (PMI) is crucial for identifying the causes of animal deaths. Autolysis, a significant postmortem process, influences PMI estimation, but its relationship with humidity is not well understood. This study aimed to improve the accuracy of PMI estimates in veterinary forensic cases by looking into how different humidity levels affect autolysis in different organs of rats. The study involved 38 male rats, examining histopathological changes in their heart, liver, and pancreas. These organs were subjected to controlled humidity levels (20%, 55%, and 80%) at a constant 22°C. Tissue samples were collected at several intervals (0 h, 12 h, 24 h, 3 days, and 8 days) for comprehensive analysis. Distinct autolytic characteristics in animal organs emerged under varying humidity conditions. The low-humidity environment rapidly activated autolysis more than the high-humidity environment. In addition, it was found that lower humidity caused nuclear pyknosis, cytoplasmic disintegration, and myofiber interruption. The liver, in particular, showed portal triad aggregation and hepatocyte individuation. The pancreas experienced cell fragmentation and an enlarged intracellular space. High humidity also caused the loss of striations in cardiac tissues, and the liver showed vacuolation. Under these conditions, the pancreas changed eosinophilic secretory granules. The study successfully established a clear connection between the autolytic process in PMIs and relative humidity. These findings are significant for developing a more accurate and predictable method for PMI estimation in the field of veterinary forensic science.

Potential Benefits of Integrin αvβ3 Antagonists in a Mouse Model of Experimental Dry Eye.

The purpose of this study was to extensively evaluate the efficacy of integrin αvβ3 antagonists for the treatment of experimental dry eye (EDE). Vitronectin, an αvβ3 ligand, was used to induce tumor necrosis factor-α gene expression in human THP-1 macrophages. To induce EDE, C57BL/6 mice were housed in a low-humidity controlled environment chamber and injected subcutaneously with scopolamine for 7 days. Subsequently, αvβ3 antagonists, including RGDfD, c(RGDfD), c(RGDiD), c(RGDfK), ATN-161, SB273005, and cilengitide, were administered topically to EDE animals under controlled environment chamber conditions. Corneal epithelial damage in EDE was assessed by fluorescein staining. The density of conjunctival goblet cells and secretion of tears was measured by period acid-Schiff staining and phenol red-impregnated cotton threads, respectively. Inflammation markers, including tumor necrosis factor-α, interleukin (IL)-1β, IL-6, IL-17A, and metalloproteinase (MMP)-9, in the pooled cornea and conjunctiva tissues were examined by real-time polymerase chain reaction. The inhibitory effects of αvβ3 antagonists on the vitronectin-induced tumor necrosis factor-α gene expression and integrin-mediated inflammatory signaling were validated in THP-1 macrophages. αvβ3 antagonists ameliorated the impairment of the corneal epithelial barrier with varying therapeutic efficacies, compared with vehicle-treated mice. c(RGDfD) and c(RGDiD) significantly protected against goblet cell loss, tear reduction, and proinflammatory gene expression in EDE. Topical applications of αvβ3 antagonists yield therapeutic benefits in EDE by promoting corneal epithelial defect healing and reducing inflammation. Antagonistic targeting αvβ3 may be a novel promising strategy to treat patients with dry eye disease.

An implicit consideration of fluid flow in the calculation of drying shrinkage of porous materials: Case of saturated concrete in low humidity environment

AbstractThe drying shrinkage of porous materials is significantly dependent on external relative humidity (). The perspective of temperature increase due to the climate change will accentuate the drying phenomenon in structures in lands and cities. The evolution of shrinkage can be determined by equivalent pore pressure consisting of capillary pressure , disjoining pressure and pressure caused by interfacial energy. For concrete structures, up to condition, standard models can reproduce the drying shrinkage experiments accurately. However, as the decreases to 30%, these models seem to be limited because the measured relationship () differs from the corresponding static equilibrium relationship as the drying occurs rapidly and the dynamic fluid flow effects on capillary pressure have been neglected. In this paper, the standard shrinkage model has been improved to take into account the dynamic flow effect and the viscoelastic behaviour of the solid skeleton. The dynamic and standard models have been compared with experimental results of drying shrinkage of concrete with two different relative humidity conditions. The standard model clearly showed its limitations at low external relative humidity . However, the dynamic model showed good prediction of mass loss and shrinkage strains at high and low humidity conditions. Furthermore, the numerical and experimental investigations indicate that not only the dynamic effects but also the additional pressure induced by surface energy should be taken into account to quantify the drying shrinkage of cement‐based materials at low condition.

Interplay between Shelf Life and Printability of Silica-Filled Suspensions.

Although fumed silica/siloxane suspensions are commonly employed in additive manufacturing technology, the interplay between shelf life, storage conditions, and printability has yet to be explored. In this work, direct ink writing (DIW) was used to print unique three-dimensional structures that required suspensions to retain shape and form while being printed onto a substrate. Suspensions containing varying concentrations of hydrophobic and hydrophilic silica were formulated and evaluated over a time span of thirty days. Storage conditions included low (8%) and high (50%) relative humidity and temperatures ranging from 4 °C to 25 °C. The shelf life of the suspensions was examined by comparing the print quality of pristine and aged samples via rheology, optical microscopy, and mechanical testing. Results showed a significant decrease in printability over time for suspensions containing hydrophilic fumed silica, whereas the printability of suspensions containing hydrophobic fumed silica remained largely unchanged after storage. The findings in this work established the following recommendations for extending the shelf life and printability of suspensions commonly used in DIW technology: (1) higher fumed silica concentrations, (2) low humidity and low temperature storage environments, and (3) the use of hydrophobic fumed silica instead of hydrophilic fumed silica.

Trifolium repens L.-Like Periodic Micronano Structured Superhydrophobic Surface with Ultralow Ice Adhesion for Efficient Anti-Icing/Deicing.

Wind turbine blades are often covered with ice and snow, which inevitably reduces their power generation efficiency and lifetime. Recently, a superhydrophobic surface has attracted widespread attention due to its potential values in anti-icing/deicing. However, the superhydrophobic surface can easily transition from Cassie-Baxter to Wenzel at low temperature, limiting its wide applications. Herein, inspired by the excellent water resistance and cold tolerance of Trifolium repens L. endowed by its micronano structure and low surface energy, a fresh structure was prepared by combining femtosecond laser processing technology and a boiling water treatment method. The prepared icephobic surface aluminum alloy (ISAl) mainly consists of a periodic microcrater array, nonuniform microclusters, and irregular nanosheets. This three-scale structure greatly promotes the stability of the Cassie-Baxter state. The critical Laplace pressure of ISAl is up to 1437 Pa, and the apparent water contact angle (CA) is higher than 150° at 0 °C. Those two factors contribute to its excellent anti-icing and deicing performances. The results show that the static icing delay time reaches 2577 s, and the ice adhesion strength is only 1.60 kPa. Furthermore, the anti-icing and deicing abilities of the proposed ISAl were examined under the environment of low temperature and high relative humidity to demonstrate its effectiveness. The dynamic anti-icing time of ISAl in extreme environments is up to 5 h, and ice can quickly fall with a speed of 34 r/min when it is in a horizontal rotational motion. Finally, ISAl has excellent reusability and mechanical durability, with the ice adhesion strength still being less than 6 kPa and the CA greater than 150° after 15 cycles of icing-deicing tests. The proposed structure would offer a promising strategy for the efficient anti-icing and deicing of wind turbine blades.

Effects of season and slope orientation on stable isotopes of different water bodies in the subalpine shrub zone of the eastern Qilian Mountains in China.

The subalpine shrub zone of the Qilian Mountains is an important water-retaining area, and it is crucial to clarify the processes of its hydrological cycle. Therefore, based on the stable isotope values of different water bodies in the subalpine shrub zone of the eastern Qilian Mountains from May to October 2019, the characteristics of δD and δ18O of different water bodies and their hydraulic relationships with each other were studied. The results showed that the stable isotope values of precipitation exhibited the largest fluctuations, while they were the most stable for groundwater. Plant transpiration was stronger than the evaporation of other water bodies. The stable isotope of precipitation was enriched in high temperature and low humidity environments. Isotopic values of plant and soil water were higher and more stable on the semi-sunny slope than on the semi-shady slope. According to the stable isotopes, there was a strong hydraulic relationship between the different water bodies in the study area, and precipitation was the ultimate source of all of them. Precipitation replenished soil water through infiltration. Part of the soil water was absorbed by plants, while the rest continued to infiltrate to replenish groundwater. Groundwater and precipitation replenished the river water.