Point Of Water Research Articles

Orienting Electron Fillings in d Orbitals of Cobalt Single Atoms for Effective Zinc–Air Battery at a Subzero Temperature

AbstractThe missions in extreme environments such as the moon, the Arctic/Antarctic, and the plateau require the operation of batteries at low temperatures even below the freezing point of water. Herein, it is reported that compressively stressed Co single atoms exhibit enhanced oxygen reduction reaction (ORR) activity and enable the effective operation of zinc–air battery at a subzero temperature. The compressive strain is generated by depositing Co single atoms on highly arced carbon layers with ultra‐small curvature radii ≈2 nm. The locally compressive strain on Co single atoms redistributes the electron fillings in d orbitals with different spatial orientations, thereby strengthening the adsorption of active intermediates and enhancing the activity toward ORR. As expected, compressively stressed Co single atoms outperform Co single atoms on a flat support without strain in terms of kinetic current density (31.09 mA cm−2 vs 0.35 mA cm−2) at 0.85 V during ORR. The integration of the catalyst into a Zn–air battery generates a superior power density of 54.8 mW cm−2 than the commercial Pt/C counterpart (24.1 mW cm−2) at −40 °C.

Beyond Local Structures in Critical Supercooled Water through Unsupervised Learning.

The presence of a second critical point in water has been a topic of intense investigation for the last few decades. The molecular origins underlying this phenomenon are typically rationalized in terms of the competition between local high-density (HD) and low-density (LD) structures. Their identification often requires designing parameters that are subject to human intervention. Herein, we use unsupervised learning to discover structures in atomistic simulations of water close to the liquid-liquid critical point (LLCP). Encoding the information on the environment using local descriptors, we do not find evidence for two distinct thermodynamic structures. In contrast, when we deploy nonlocal descriptors that probe instead heterogeneities on the nanometer length scale, this leads to the emergence of LD and HD domains rationalizing the microscopic origins of the density fluctuations close to criticality.

Groundwater development and management constraints in drought prone Chiredzi and Zvishavane Districts, Zimbabwe

Communities in drought-prone areas continued to fall into new vulnerability traps due to increasing water demand and stress. The study assessed groundwater development and management constraints in the Chiredzi and Zvishavane districts of Zimbabwe. Groundwater development and management activities implemented in the study area were supported by the Government of Zimbabwe, development partners, humanitarian agencies, private sector corporate social responsibility, and individual households. Interpretivism and realism philosophical positionalities were employed in the study. Whilst interpretivism’s inductive approach enabled an in-depth qualitative methodology and understanding of the groundwater constraints, the direct realism provided quantitatively driven scientific and statistical data to answer the research questions exhaustively. Quantitative data was gathered through a household questionnaire administered to randomly selected respondents. Qualitative data was gathered using focus group discussions, key informant interviews, direct field observations and measurements. Respondents to the key informant interview were drawn from district-level government officials, local authorities, traditional leaders, village pump minders and water point committee members.Due to climate change, communities have experienced an increase in the decline in groundwater levels during the dry season evidenced by demand surpassing supply. Temperature increase and rainfall decline experienced by 97%, and 73% of respondents from Chiredzi and Zvishavane districts, respectively, resulted in increased withdrawal and reduced groundwater recharge. Participants revealed that groundwater withdrawal is on the increase while recharge is declining as evidenced by the increase in conflicts at waterpoints. The 85% coverage by low groundwater-yielding basement hydrogeological formation suggested a slight reduction in groundwater recharge due to reduced rainfall and increased community vulnerability to drought. Village Pump Minders and Water Point Committees experienced operational challenges that affected the maintenance of groundwater sources. This was mainly due to the incapacitation of local institutions in terms of financial resources, equipment, and skills. The study recommends a groundwater replenishment model to improve groundwater aquifer recharge. Strengthening of local institutions improves the management of groundwater using integrated water resources management (IWRM) framework that promotes coordination between competing uses.

Enhancing Rubber Vulcanization Cure Kinetics: Lowering Vulcanization Temperature by Addition of MgO as Co-Cure Activator in ZnO-Based Cure Activator Systems.

Vulcanization is a chemical modification of rubber that requires a considerable amount of thermal energy. To save thermal energy, the kinetics of rubber vulcanization should be improved. In this article, the curing properties of rubber vulcanization are thoroughly investigated using the moving die rheometer (MDR) technique. To enhance the kinetics in different stages of ZnO-based sulfur vulcanization systems, small amounts of MgO were added. The results revealed that the small amount of 1 to 2 phr (per hundred grams of rubber) of MgO in the controlled 5 phr ZnO-based curing systems can significantly improve the curing kinetics. For example, the optimum curing time of 1 phr MgO added to the 5 phr ZnO-containing semi-efficient vulcanization system at different temperatures was more than half that of the controlled 5 phr ZnO-only compound. While maintaining a similar rate of vulcanization, the vulcanization temperature can be reduced by up to 20 °C by using MgO as a co-cure activator, which exhibits similar or better rheometric mechanical properties compared to the controlled compounds. With the addition of MgO as a co-cure activator, the vulcanization reactions become very fast, enabling vulcanization to be completed, even at the boiling point of water (100 °C) with an affordable curing time (<1 h). By reducing the vulcanization temperature, the scorch safety time can be enhanced in the ZnO/MgO-based binary cure activator-containing vulcanizates. Overall, MgO could be a potential candidate as a co-cure activator with ZnO for the vulcanization of rubber, offering better economical and eco-friendly methods.

Assessment of the coating quality in a top-spray fluidized bed coater: An experimental study

The effects of multiple factors on the coating process in a top-spray fluidized bed coater were systematically investigated. The intra-particle coating variability could be assessed by the SEM measurement. Fluidizing gas temperature (0.5–0.9, normalized by the boiling point of water), injection velocity (0.115–0.397 m/s) and concentration (2.1–5.2 wt%) of the coating liquids, atomizing pressure (1.0–3.0 bar) and nozzle height (378 and 470 mm) were found to impact particle agglomeration, coating efficiency and thickness dramatically. Their impact trends and mechanisms were analyzed in detail. The effect of the particle size (0.22–1.26 mm) on particle agglomeration behavior was highlighted. Critical injection velocities and the corresponding agglomeration ratios were experimentally determined. Finally, it was established that there were no universal optimum conditions for the spray coating process, and they can be experimentally determined according to the attributes of interest.

Quantitative observation of water phase transition in gas diffusion layers utilizing advanced in situ differential scanning calorimetry

The study investigates the freezing behavior of supercooled water in gas diffusion layers (GDLs) of polymer electrolyte fuel cells (PEFCs). Using an innovative advanced in situ differential scanning calorimetry (advanced DSC) technique, we analyze phase transitions within GDLs at a single-cell scale, excluding impacts of catalyst layers and membranes. This method overcomes the limitations of traditional DSC, allowing variable water saturation and distribution. We find that freezing-thawing and drying-saturating cycles contribute to noticeable variations in the freezing temperature (Tonset) of supercooled water, ranging from −6 °C to −15 °C, attributed to the heterogeneous surface of GDL and water redistribution. Repeated drying-saturating cycles remove nucleation seeds, lowering the freezing point of water − a "cleaning effect." The freezing probability reduces at lower saturation levels, influenced by waterproof treatment uniformity on GDLs. Residual ice can be detrimental to the cold-start capability of PEFCs, as it promotes freezing of supercooled water around −1 °C. Our findings enhance understanding of water behavior in GDLs and its impact on PEFC cold-start performance. Applying this technique to other cell components, such as the catalyst layer, could further elucidate water freezing dynamics in PEFCs and guide the innovation of more reliable cell components for PEFC applications in broader climates.

Prediction of Phase Equilibrium Conditions and Thermodynamic Stability of CO2-CH4 Gas Hydrate

With the large-scale promotion and application of CO2 flooding, more and more engineering problems have emerged. Due to the high CO2 mole fraction, the associated gas of CO2 flooding very easily forms solid hydrates, compared to conventional natural gas. This has resulted in production decline or shutdown. Understanding the phase equilibrium conditions for hydrate formation in production fluids is crucial for hydrate prevention and control. In this study, accurate predictions of CO2-CH4 mixed gas hydrate formation conditions were performed using theoretical models. The temperature and pressure ranges for hydrate formation were calculated for different CO2 mole fraction, ranging from −11.5 °C to 20.85 °C and from 0.81 MPa to −28.1 MPa, respectively. Based on the calculated phase equilibrium data, a multi-parameter empirical model was developed using polynomial fitting. The calculation errors for the multi-parameter empirical model were 3.09%. The multi-parameter empirical model established in this study can avoid complex thermodynamic equilibrium calculations and has the advantages of simplicity, high accuracy, and wide coverage of downhole conditions. Based on the calculated phase equilibrium data, the dissociation enthalpy of CO2-CH4 hydrate below and above the freezing point of water was calculated. The results showed that an increase in CO2 mole fraction led to an increase in hydrate dissociation enthalpy and enhanced thermodynamic stability, making hydrate prevention more challenging. Our work can contribute to the optimization of CO2 production fluid treatment processes and the development of hydrate prevention and control technologies.

Animal welfare on Argentinean dairy farms based on the Welfare Quality® protocol framework

Animal welfare is a multidimensional concept that comprises animal health, mental state and natural living conditions and plays an essential role in dairy production. On dairy farms, animal welfare can be assessed with different available protocols. The goal of this study was to describe the animal welfare strengths and hazards of dairy farms in Argentina using the Welfare Quality® protocol as a framework. We conducted a literature search using the Scopus database to find articles related to the measures included in the protocol for Argentinean farms. Furthermore, we included data from national statistics. The data available were grouped according to the four principles of the protocol: good feeding, good housing, good health, and appropriate behavior. The results suggest that cows are well nourished; however, water provision is limited because grazing cows need to walk long distances, between 244 m and 460 m, to access a water point. Heat stress is a notable constraint affecting the welfare of cows, as the temperature-humidity index is greater than 72 for at least 100 days during the year. The prevalence of lameness and downer cows was estimated to be 2.2% and 0.7%, respectively, which are below the thresholds for ensuring good welfare. The annual average somatic cell count was 385,000/ml, close to the cutoff recommended for good health. The mortality rate of the cows was higher than recommended. The main strength of Argentinean dairy farms in relation to animal welfare is access to pasture throughout the year for 90% of the farms.

Identification of local structures in water from supercooled to ambient conditions.

Studies of water thermodynamics have long been tied to the identification of two distinct families of local structures, whose competition could explain the origin of the many thermodynamic anomalies and the hypothesized liquid-liquid critical point in water. Despite the many successes and insights gained, the structural indicators proposed throughout the years were not able to unequivocally identify these two families over a wide range of conditions. We show that a recently introduced indicator, Ψ, which exploits information on the hydrogen bond network connectivity, can reliably identify these two distinct local environments over a wide range of thermodynamic conditions (188-300K and 0-13 kbar) and that close to the liquid-liquid critical point, the spatial correlations of density fluctuations are identical to those of the Ψ indicator. Our results strongly support the idea that water thermodynamic properties arise from the competition between two distinct and identifiable local environments.

Determinants of the operational performance of community-managed handpumps in rural Mozambique: An analysis of five years of cross-sectional sustainability assessments

Improving rural water supply sustainability in sub-Saharan Africa remains a major challenge. This study analysed five-years of cross-sectional sustainability check data collected annually between 2011 and 2016 (except 2015) to investigate factors influencing the operational performance of community-managed handpumps in rural Mozambique. Logistic and negative binomial regression was performed using multiple outcome measures of functionality, reliability and continuity. Average marginal effects (AMEs) were estimated to assess the effects of the predictors and mediation analysis was conducted to examine the role of women's participation.Higher levels of handpump performance were associated with financial records quality and update frequency, water committees with spare parts in stock, and committee annual revenue. The AME of high quality or recently updated financial records for non-functionality was estimated to be −0.40 (95% confidence interval [CI], −0.56 to −0.25), which is interpreted as a 40% lower probability of a water point being non-functional compared to the reference group. Water committees with a spare part stock exhibited a preventive effect on both non-functionality and breakdowns in the past 12 months, reducing their probability by 10% (AME, 95% CI, −0.17 to −0.03) and by 18% (AME, 95% CI, −0.30 to −0.05), respectively. Annual committee revenue up to 2,000 MZN (57 USD) reduced the probability of breakdowns by 25% (AME, 95% CI, −0.45 to 0.05). Handpumps were 10% (AME, 95% CI, 0.03 to 0.17) more likely to be non-functional when women were in the committee management positions. Conversely, female maintenance group members were associated with reduced breakdowns in the multivariate regression analysis (odds ratio, 0.48; 95% CI, 0.24 to 0.95).Increasing outreach of post-construction support on capacity building for water committees, particularly on user fee collection, maintaining financial records, replenishing spare parts, and increased participation of women in the maintenance group, may contribute to greater sustainability of rural water points.

Evaluation of vulnerable zones to water pollution in the lower Soummam alluvial aquifer, Bejaia, Algeria

Abstract Understanding the critical relationship between the Soummam River and its alluvial aquifer is crucial for the protection of this vital water resource. The approach is based on monitoring the spatial and temporal evolution of physico-chemical parameters and identifying their origin through correlation with the geology and piezometry of the alluvial aquifer; this will be achieved using differential gauging and hydrogeochemical tracing. This will provide valuable information for the management and protection of this precious water resource. The case study focuses on the alluvial aquifer of the lower Soummam Valley in Bejaia, Algeria, where a unique natural barrier upstream creates a close hydraulic relationship between the river and the aquifer. This allows for water exchange, which we investigated through two sampling campaigns (high and low water) at 32 water points (boreholes, wells and stations). By tracking the movement of special chemical tracers in both the Soummam River and the underlying alluvial aquifer, this study confirms a direct hydraulic connection between them. This means that water can flow from the river into the aquifer, highlighting the potential risk of water pollution. This has helped us to identify areas where pollution from the river could seep into the groundwater, threatening the drinking water supply.

Understanding the conversion mechanisms in supercritical water conditions of PET as a model compound of plastic wastes

In this work, polyethylene terephthalate (PET) was used as a model compound for understanding the conversion mechanism of plastic wastes through supercritical water gasification (SCWG) for producing: i) a gas rich in methane/hydrogen; and ii) for obtaining valuable molecules to be recycled in chemical processes (e.g., benzoic and acetic acids).The experiments were conducted at two different temperatures (above the critical point of water): 450 °C and 600 °C, in order to study the influence of this parameter on the conversion yield. The holding time in the reactor was set at 30 min for all trials. The experimental data were compared to the thermodynamic equilibrium calculations and the results showed that increasing the temperature from 450 °C to 600 °C, the total gas yield is highly improved (from 8.6 mol gas/kg of dried feedstock to 22 mol gas/kg of dried feedstock). The experiments with Raney-nickel catalyst indicated a significant improvement of the carbon conversion yield, which led to a higher gas production from mild to higher temperatures. The maximum total gas yield obtained with this catalyst was 63.4 mol gas/kg of dried feedstock at 600 °C, which is almost 3 times higher than that obtained at the same operating conditions without catalyst. The HHV of the obtained gas at 600 °C with the catalyst was 64.7 MJ/kg gas and 57.9 MJ/kg gas at 450 °C. Additionally at mild operating temperatures (450 °C), the obtained performance with the catalyst was even higher than that obtained at 600 °C without catalyst (50 mol gas/kg dried feedstock and 22 mol gas/kg dried feedstock, respectively), which is the major contribution of this work. At mild temperatures (450 °C) the methane production is highly favored, meanwhile at 600 °C the hydrogen production is enhanced. The methane yield obtained at 450 °C was 21.3 mol CH4/kg dried feedstock and the hydrogen yield obtained at 600 °C was 20.6 mol H2/kg dried feedstock. In the aqueous phases obtained from the experiments performed without catalyst at 450 °C, it was found valuable intermediate species such as benzoic and acetic acids (at a concentration of 4462 mg/L and 946 mg/L, respectively). This study represents a sustainable approach for valorizing plastic wastes by catalytic SCWG process.

Frostbite incidence is a selective term and dependable on methodology — a narrative review

Introduction: Frostbite is freezing of the tissue that mostly affects skin but also the underlying tissues. It results from prolonged exposure to temperatures below the freezing point of water (0°C). One of the many consequences of climate change is extreme cold events, which increase the risk of frostbite in the general population, particularly among individuals who are involuntarily exposed to cold for prolonged periods of time. Although frostbite has been a known phenomenon for a long time, occurring as early as 5000 years ago, the exact incidence of frostbite is not known. This is partly due to variable internal (frostbite susceptibility, hydration status, protective garments) and external etiological factors (wind chill, precipitation, altitude), that never coincide all at the same time. Objectives: The objective was to compare the incidence rates of frostbite in the published studies that focused on frostbite incidence. Methods: Out of a total of 61 studies using the keywords “frostbite” and “incidence” on PubMed, we selected seven that dealt with frostbite incidence over 20 years. We briefly summarized and compared the results of the studies. Results: The comparison of the seven studies shows a great variability of frostbite incidence depending on the population, its size, and the method of data collection. Studies that included civilian populations have significantly lower frostbite incidence rates than studies focusing on individuals who are exposed to temperatures below 0°C for extended periods, such as mountaineers, military personnel, workers in cold storage houses or homeless people. The results highlight different incidence rates for different populations and indicate that retrospectively collected data are insufficiently comparable among studies. Frostbite incidence, expressed as the ratio of injured individuals to non-injured inhabitants, is only comparable in studies using the same methodology. Enhanced frostbite susceptibility is a confirmed fact and was generally not considered in most of the studies. Conclusions: Frostbite incidences of the included studies are insufficiently comparable to draw any conclusions on possible general frostbite incidence in a population. To enhance our ability to estimate or predict frostbite occurrences within the general population, establishing an international or national frostbite registry in high-risk countries could be helpful. 

Application of ionic liquids in ion-selective electrodes and reference electrodes: A review.

Ionic liquids (ILs) are organic chemical compounds that are composed only of ions, a large organic cation and a smaller inorganic or organic anion. These are salts whose melting point is lower than the boiling point of water. ILs have many interesting properties, thanks to which they find great practical applications in analytics, electrochemistry, separation techniques, catalysis and others. One of the many areas of application of ionic liquids is sensors especially electrochemical sensors including ion-selective electrodes. In this case, the properties of ILs that are particularly useful include very good electrical conductivity, high electrochemical stability, good extraction properties, hydrophobic character and compatibility with other materials, e. g. polyvinyl chloride plasticizers or carbon nanomaterials. ILs were used as components of ion-selective membranes, both polymeric ones based on PVC and membranes in carbon paste electrodes. ILs performed various functions in these membranes, including lipophilic ionic additive, ionophore/ion exchanger, plasticizer, transducer media and matrix. They were also used as a component of the intermediate layer in solid contact ISEs. The last chapter presents examples of the use of ILs in reference electrodes. This review discusses the use of ionic liquids in ion-selective electrodes (ISEs) and reference electrodes over the last ten years.

Ecological determinants of spotted hyena Crocuta crocuta occupancy in Comoé National Park, Côte d’Ivoire

Knowledge of the large carnivore guild is important in view of a possible lion reintroduction into the Comoé National Park (CNP), northern Côte d’Ivoire. We used camera trapping to assess activity patterns, habitat selection, and ecological factors influencing the occupancy of the spotted hyena Crocuta crocuta. Our results showed that the presence of leopard Panthera pardus, the only current other large carnivore and thus potential competitor, did not influence hyena occupancy. Hyena occupancy was only significantly related to Euclidian distance to nearest water point. Manly’s alpha habitat selection index values show a preference of spotted hyena for shrub savannah (αSa = 0.71), and Pianka’s overlap index showed low spatial competition with leopard (OIJ(PNC) = 0.12). Our findings showed that spotted hyena were mostly nocturnal, and generally active at the same time slots with leopard, leading to a high index of temporal overlap (OIJ(time) = 0.78). The kernel density estimation confirmed that spotted hyenas and leopard shared almost half of their activity patterns (Δ1 = 0.49 and 95% CI = 0.26–0.71). Prey diversity is high in CNP but anthropogenic threats appear to suppress population growth of prey and predators. Conservation efforts should continue to reduce pressures before contemplating a potential lion Panthera leo reintroduction.

Distribution of Dwarf Crocodile (Osteolaemus Tetraspis Cope, 1861) Populations on the Outskirts of the Ebo Forest: Implications for Conservation

Purpose: The study was carried out in three riparian areas of the Ebo forest (Iboti, Lognanga and Ndokmem-North zones) to determine the distribution and status of dwarf crocodiles, and environmental factors influencing their distributions.  &#x0D; Materials and Methods: Survey on the various listed sites were carried out during the months of April, May and June 2023. The Qgis software was used to produce the distribution map of dwarf crocodiles in the periphery of the Ebo forest from the coordinates recorded at 11 water points using a GPS and 37 fishermen/ hunters were interview.&#x0D; Findings: The species were classified according to their status defined according to the IUCN red list protocol. The study showed that of the 11 water points studied, 6 were home to dwarf crocodiles, representing a proportion of 54.54%. Although we did not observed dwarf crocodiles in the watercourses in the Iboti zone, their presence is more established in the Lognanga zone (60%) than in the Ndokmem-north zone (40%). The average density of dwarf crocodiles in the periphery of the Ebo forest is around 0.50 crocodiles/km of riverbank covered. This implies that the population of dwarf crocodiles is decreasing and there is high need to increase conservation efforts to protect it from disappearing within the Ebo forest area.&#x0D; Implications to Theory, Practice and Policy: To guarantee the survival and viability of crocodiles in the periphery of the Ebo forest, it is necessary to opt for organic agriculture, monitoring the quality of rivers and water bodies and regular ecological monitoring of crocodiles.

Rural Water Point Functionality Estimates and Associations: Evidence From Nine Countries in Sub‐Saharan Africa and South Asia

AbstractSustained functionality of rural water systems is a global challenge. Research on factors contributing to rural water system functionality is largely restricted to hand pumps from single geographies. We analyzed monitoring data from 10 drinking water supply programs in nine sub‐Saharan African and South Asian countries collected between 2017 and 2020. Data included 1,805 randomly selected water points (tap stands, spring protections, rainwater collection, and boreholes and hand‐dug wells with hand pumps) from two cross‐sectional samples: older construction (1–12 years old) and new construction (&lt;1 year). Data collection included observations of water point functionality (“water available”) and management committee questionnaires. Overall, 79% of older construction and 92% of new construction water points were functional. In a mixed effects logistic regression to identify factors contributing to functionality within the older construction sample, piped water tap stands had lower odds of functioning than boreholes with hand pumps (OR = 0.26, 95% CI:0.15–0.46). Water points in communities with fewer available water points, those with operational water management committees (which meet often, collect fees, and can name someone for maintenance), and those with financial savings were associated with higher functionality. As piped water system provision increases in line with international development goals, our results suggest that the benefits of providing higher levels of water service should be carefully considered alongside the technological, institutional, and financial investment required to operate and maintain more complex piped water systems in rural settings.

Novel Apoplastic Antifreeze Proteins of Deschampsia antarctica as Enhancer of Common Cell Freezing Media for Cryobanking of Genetic Resources, a Preliminary Study.

Antifreeze proteins (AFPs) are natural biomolecules found in cold-adapted organisms that lower the freezing point of water, allowing survival in icy conditions. These proteins have the potential to improve cryopreservation techniques by enhancing the quality of genetic material postthaw. Deschampsia antarctica, a freezing-tolerant plant, possesses AFPs and is a promising candidate for cryopreservation applications. In this study, we investigated the cryoprotective properties of AFPs from D. antarctica extracts on Atlantic salmon spermatozoa. Apoplastic extracts were used to determine ice recrystallization inhibition (IRI), thermal hysteresis (TH) activities and ice crystal morphology. Spermatozoa were cryopreserved using a standard cryoprotectant medium (C+) and three alternative media supplemented with apoplastic extracts. Flow cytometry was employed to measure plasma membrane integrity (PMI) and mitochondrial membrane potential (MMP) postthaw. Results showed that a low concentration of AFPs (0.05 mg/mL) provided significant IRI activity. Apoplastic extracts from D. antarctica demonstrated a cryoprotective effect on salmon spermatozoa, with PMI comparable to the standard medium. Moreover, samples treated with apoplastic extracts exhibited a higher percentage of cells with high MMP. These findings represent the first and preliminary report that suggests that AFPs derived from apoplastic extracts of D. antarctica have the potential to serve as cryoprotectants and could allow the development of novel freezing media.

Ice‐Ocean Interactions on Ocean Worlds Influence Ice Shell Topography

AbstractThe freezing point of water is negatively dependent on pressure; therefore in any ocean without external forcing it is warmest at the surface and grows colder with depth. Below floating ice on Earth (e.g., ice shelves or sea ice), this pressure dependence combines with gradients in the ice draft to drive an ice redistribution process termed the “ice pump”: submerged ice melts, upwells, and then refreezes at shallower depths. Ice pumping is an exchange process between the ocean and overhead ice that results in unique ice compositions and textures and influences the distribution of sub‐ice habitats on Earth. Here, we scale recent observations from Earth's ice shelves to planetary conditions and find that ice pumping is expected for a wide range of possible sub‐ice shell pressures and salinity at other ocean worlds such as Europa and Enceladus. We show how ice pumping would affect hypothetical basal ice shell topography and ice thickness under varying ocean conditions and demonstrate how remote sensing of the ice shell draft can be used to estimate temperature gradients in the upper ocean ahead of in situ exploration. For example, the approximately 22 km gradient observed in Enceladus' ice shell draft between the south pole and the equator suggests a temperature differential of 0.18 K at the base of the ice shell. These concepts can extend the interpretation of observations from upcoming ocean world missions, and link ice shell topography to ice‐ocean material exchange processes that may prove important to overall ocean world habitability.

A new interpolation equation in the ITS-90 subrange from the triple point of water to the freezing point of indium

For all the subranges above 0.01 °C, other than the interpolation between the triple point of water (TPW) to the melting point of gallium, temperatures on the international temperature scale of 1990 (ITS-90) are specified without the melting point of gallium. This study suggests a new interpolation equation in the subrange from the TPW to the freezing point of indium which is a polynomial of fractional third order with two coefficients to be determined by the measuring values of standard platinum resistance thermometers (SPRTs)’ resistance ratios at the melting point of gallium (W Ga) and at the freezing point of indium (W In). A sample set of 30 SPRTs from various countries and laboratories is used to quantify the comparisons between this new interpolation and the ITS-90. Analyses show that the reproducibility is significantly improved compared with the ITS-90 in the same subrange. The peak value of overlapping subrange inconsistencies (SRI) from TPW to the melting point of gallium is reduced from 0.91 mK to 0.21 mK. Both the mean and standard deviation of the SRI peak values for the new equation decrease by approximately a factor of four compared to those of the ITS-90 (mean decreasing form 0.20 mK to 0.05 mK and standard deviation decreasing form 0.32 mK to 0.07 mK). Type 3 non-uniqueness (NU3) determinations of the same subrange have also been looked into with a data set of four SPRTs compared in thermostatic baths using a copper block and the results show that NU3 scales down from a range −0.15 mK–0.25 mK of the ITS-90 to −0.10 mK–0.15 mK of the new interpolation equation. Propagation of Uncertainties investigation shows that the new equation inflates merely 7% the measurement uncertainties of fixed points in a relatively short interval from 30 °C to 60 °C.