Variable Concentrations Research Articles

Enhanced broadband IR absorption and electrical characteristics of silicon variably hyperdoped by sulfur (1018-1021 cm−3) by ion implantation/pulsed laser annealing

Spectral range of crystalline silicon absorption could be extended to near- and even mid-infrared region by its hyperdoping via ion-implantation technology, requiring the following thermal annealing for removing ion-induced defects, recrystallizing the crystalline structure and activating the doping impurity. In this article, the crystalline structure, chemical and electrical characteristics of sulfur-hyperdoped silicon layers with broadly variable impurity concentration (1018-1021 cm−3) and annealed by a nanosecond laser were investigated for the first time by Raman, energy-dispersion x-ray and infrared spectroscopy, as well as by van der Paw and Hall measurements, respectively. The most preferable sulfur concentration for silicon hyperdoping from the point of view of impurity optical and electrical activation was found to be 1020 cm−3.

Influence of Copper on Oleidesulfovibrio alaskensis G20 Biofilm Formation.

Copper is known to have toxic effects on bacterial growth. This study aimed to determine the influence of copper ions on Oleidesulfovibrio alaskensis G20 biofilm formation in a lactate-C medium supplemented with variable copper ion concentrations. OA G20, when grown in media supplemented with high copper ion concentrations of 5, 15, and 30 µM, exhibited inhibited growth in its planktonic state. Conversely, under similar copper concentrations, OA G20 demonstrated enhanced biofilm formation on glass coupons. Microscopic studies revealed that biofilms exposed to copper stress demonstrated a change in cellular morphology and more accumulation of carbohydrates and proteins than controls. Consistent with these findings, sulfur (dsrA, dsrB, sat, aprA) and electron transport (NiFeSe, NiFe, ldh, cyt3) genes, polysaccharide synthesis (poI), and genes involved in stress response (sodB) were significantly upregulated in copper-induced biofilms, while genes (ftsZ, ftsA, ftsQ) related to cellular division were negatively regulated compared to controls. These results indicate that the presence of copper ions triggers alterations in cellular morphology and gene expression levels in OA G20, impacting cell attachment and EPS production. This adaptation, characterized by increased biofilm formation, represents a crucial strategy employed by OA G20 to resist metal ion stress.

Analysis of Ca1-xSrxCO3 phases generated by competitive Sr2+ replacement in pre-formed aragonite

The ratio of Sr/Ca ions in marine biogenic minerals is considered advantageous for tracking geochemical and biomineralization processes that occur in the oceans. It is debatable, though, whether the ratio in biominerals such as coral skeleton is simply related to values in the seawater environment or controlled by the organism. Recent data show that coral larvae produce partially disordered immature aragonite in Mg-containing Sr-poor calcifying fluids, which transforms into well-ordered aragonite in Mg-depleted Sr-enriched environments, upon animal metamorphosis into the sessile polyp state.Inspired by the process in young coral, we explored in vitro substitution of Ca by Sr in aragonite by exposing aragonite crystals precipitated a priori to Sr solutions with variable concentrations. The resulting biphasic material, comprised of Sr-doped aragonite and Ca-doped strontianite, was carefully analyzed for foreign cation substitution in each polymorph. This allowed to establish a linear correlation between Sr levels in mineralizing solutions and Sr in aragonite as well as Ca in strontianite. It indicated that ca. 5-fold higher Sr solution concentration is needed for substitution in the crystal to reach the level found in corals. It also provided with Sr levels required for a putative strontianite phase to form.

Understanding and forecasting consumer sequential multiscreen viewing behavior

Nowadays, consumers often sequentially use multiple screens to watch media content, so that firms advertise on TV, websites, and apps at the same time period to reach consumers widely. However, sequential multiscreeners may repeated exposure to the same advertisement and develop negative attitudes. Utilizing real-world data, this paper employs a zero-inflated negative binomial (ZINB) model to predict consumer sequential multiscreen viewing frequency. Moreover, we quantify the net impacts of significant predictors on the sequential multiscreen viewing frequency and find that media factors (such as number of viewing devices, internet access, PC screen size, cellphone ownership, and device concentration ratio) have equivalent impacts as audience factors (including user demographics and past viewing behaviors) and the new created variable device concentration ratio has the largest impact. The accurate prediction and quantified net impacts can guide firms allocate their advertising budget more efficiently across multiple screens and avoid consumer overexposure to the same ad content.

Modes of administration of nitric oxide devices and ventilators flow-by impact the delivery of pre-determined concentrations

BackgroundNitric oxide (NO) is a strong vasodilator, selectively directed on pulmonary circulation through inhaled administration. In adult intensive care units (ICU), it is mainly used for refractory hypoxemia in mechanically ventilated patients. Several medical delivery devices have been developed to deliver inhaled nitric oxide (iNO). The main purpose of those devices is to guarantee an accurate inspiratory NO concentration, whatever the ventilator used, with NO2 concentrations lower than 0.3 ppm. We hypothesized that the performances of the different available iNO delivery systems could depend on their working principle and could be influenced by the ventilator settings. The objective of this study was to assess the accuracy of seven different iNO-devices combined with different ICU ventilators’ flow-by to reach inspiratory NO concentration targets and to evaluate their potential risk of toxicity.MethodsWe tested seven iNO-devices on a test-lung connected to distinct ICU ventilators offering four different levels of flow-by. We measured the flow in the inspiratory limb of the patient circuit and the airway pressure. The nitric oxide/nitrogen (NO/N2) flow was measured on the administration line of the iNO-devices. NO and NO2 concentrations were measured in the test-lung using an electrochemical analyzer.ResultsWe identified three iNO-device generations based on the way they deliver NO flow: “Continuous”, “Sequential to inspiratory phase” (I-Sequential) and “Proportional to inspiratory and expiratory ventilator flow” (Proportional). Median accuracy of iNO concentration measured in the test lung was 2% (interquartile range, IQR -19; 36), -23% (IQR -29; -17) and 0% (IQR -2; 0) with Continuous, I-Sequential and Proportional devices, respectively. Increased ventilator flow-by resulted in decreased iNO concentration in the test-lung with Continuous and I-Sequential devices, but not with Proportional ones. NO2 formation measured to assess potential risks of toxicity never exceeded the predefined safety target of 0.5 ppm. However, NO2 concentrations higher than or equal to 0.3 ppm, a concentration that can cause bronchoconstriction, were observed in 19% of the different configurations.ConclusionWe identified three different generations of iNO-devices, based on their gas administration modalities, that were associated with highly variable iNO concentrations’ accuracy. Ventilator’s flow by significantly impacted iNO concentration. Only the Proportional devices permitted to accurately deliver iNO whatever the conditions and the ventilators tested.

Evaluation of GHG Emissions on Climate of the Braced States in the Niger Delta

This study evaluates greenhouse gas emissions on the climate in the BRACED States of the Niger Delta. The emission of greenhouse gases leads to deforestation, reduced vegetation, and a decline in biodiversity. To achieve the study, an ex post facto research design was used. The study utilised field measurements and historical data to assess these factors. Data were collected and monitored from twelve distinct locations between September 2022 and February 2023. The findings indicate that Akwa Ibom had the lowest concentrations of greenhouse gas and climate variables. The concentrations of greenhouse gases and climate variables were found to be lowest in Akwa Ibom and Rivers States. Similarly, Rivers, Cross Rivers, and Edo States exhibited comparatively lower quantities of carbon dioxide emissions and low rainfall. The study's findings observed a strong correlation between climate (temperature and rainfall) and greenhouse gas emissions in the BRACED states. Statistical analysis at the P<0.05 level of significance indicates that greenhouse gas emissions account for around 32.5% of the observed variations. This analysis offers a method for determining the climate impact of GHG emissions. It is recommended that law on gas flaring activities should be brought to actions.

The Use of Eco-Enzyme as a Larvacide for Aedes aegypti Mosquito Larvae

Nearly half of the world's population is at risk of dengue infection, an arboviral infection that is typically spread by the mosquito Aedes aegypti. Insecticide use and community awareness campaigns are the main vector control strategies currently in use in some countries, and they didn’t done many ways to reduce dengue. Eco-enzyme is the product of fermentation from organic waste such as vegetable, fruit, and sugar. Eco-enzyme can be used in agriculture, medicine, and others. This study aims to analyze the toxicity level of ecoenzyme as the larvicide for Aedes aegypti larvae. An analytical experimental study were conducted in Bionas Parasitology Laboratory from February to March 2024. As many as 20 Aedes aegypti larvae were used in each of exposure. Each exposure were replicated four times. The mortality of Aedes aegypti larvae was analyzed by a two-way ANOVA test, followed by a Fisher's least significant defference (LSD) post hoc test with a significance level of (p<0.01). This data was analysed by Statistical Product and Service Solutions(SPSS)Inc. 25.0. The concentrations of ecoenzyme induce mortality of the third instar of Aedes aegypti larvae were started from 2% concentration, and the highest was found in 10% concentrations which resulted in average of 50% mortality. In this context, the analysis results show that time, concentration, and the interaction between time and concentration have a significant influence on the observed quantities. These findings can have important implications in the context of studies or experiments related to the variables being tested. Below are the profile plots of each variable (concentration and time of exposure) which give significant influence on the mortality of Aedes larvae

Mineral chemistry of the Geyer SW tin skarn deposit: understanding variable fluid/rock ratios and metal fluxes

AbstractThe Geyer tin skarn in the Erzgebirge, Germany, comprises an early skarnoid stage (stage I, ~ 320 Ma) and a younger metasomatic stage (stage II, ~ 305 Ma), but yet, the source and distribution of Sn and the physicochemical conditions of skarn alteration were not constrained. Our results illustrate that contact metamorphic skarnoids of stage I contain only little Sn. REE patterns and elevated concentrations of HFSE indicate that garnet, titanite and vesuvianite of stage I formed under rock-buffered conditions (low fluid/rock ratios). Prograde assemblages of stage II, in contrast, contain two generations of stanniferous garnet, titanite-malayaite and vesuvianite. Oscillation between rock-buffered and fluid-buffered conditions are marked by variable concentrations of HFSE, W, In, and Sn in metasomatic garnet. Trace and REE element signatures of minerals formed under high fluid/rock ratios appear to mimic the signature of the magmatic-hydrothermal fluid which gave rise to metasomatic skarn alteration. Concomitantly with lower fluid-rock ratio, tin was remobilized from Sn-rich silicates and re-precipitated as malayaite. Ingress of meteoric water and decreasing temperatures towards the end of stage II led to the formation of cassiterite, low-Sn amphibole, chlorite, and sulfide minerals. Minor and trace element compositions of cassiterite do not show much variation, even if host rock and gangue minerals vary significantly, suggesting a predominance of a magmatic-hydrothermal fluid and high fluid/rock ratios. The mineral chemistry of major skarn-forming minerals, hence, records the change in the fluid/rock ratio, and the arrival, distribution, and remobilization of tin by magmatic fluids in polyphase tin skarn systems.

Vitamin B12 status and the risk of developing sepsis in patients with bacterial infection: a prospective observational cohort study

BackgroundData have shown that vitamin B12 has immunomodulatory effects via different pathways, which could influence the pathophysiology of sepsis. The objective of this study was to investigate whether vitamin B12 levels, assessed by the measurement of holotranscobalamin (HTC), total vitamin B12 (B12), and methylmalonic acid (MMA, which accumulates in case of B12 deficiency), are associated with the development of sepsis in patients with onset of bacterial infection.MethodsThis was a single-center, prospective observational pilot study. Adult patients who presented to the emergency department with bacterial infection confirmed by a positive microbiological culture result were included in the study and followed up for 6 days to assess whether they developed sepsis or not. The primary objective was to compare HTC concentration in patients who developed sepsis to those who did not develop sepsis. Secondary objectives were the evaluation of B12 and MMA concentrations in those two groups. Multiple logistic regression models were used, with presence of sepsis as the outcome variable, and HTC, B12, and MMA concentrations as predictor variables, separately, and adjusted for potential confounders.ResultsFrom 2019 to 2022, 2131 patients were assessed for eligibility, of whom 100 met the inclusion criteria. One patient was excluded from the analysis due to missing data. Of the 99 patients, 29 developed sepsis. There was no evidence for an association between HTC or B12 concentration and the development of sepsis (OR 0.65, 95% CI 0.31–1.29, p = 0.232, OR 0.84, 95% CI 0.44–1.54, p = 0.584, respectively). There was an association between MMA concentration and the development of sepsis, with a positive effect, i.e. with increasing MMA, the odds for sepsis increased (OR 2.36, 95% CI 1.21–4.87, p = 0.014). This association remained significant when adjusted for confounders (OR 2.72, 95% CI 1.23–6.60, p = 0.018).ConclusionsOur study found an association between elevated MMA concentration and the development of sepsis. We did not find an association between HTC and B12 concentrations and the development of sepsis. Further, larger studies are warranted, as it could lead to interventional trials investigating whether B12 supplementation provides a clinical benefit to patients with infection or sepsis.Trial registrationThe study was registered on ClinicalTrials.gov under the identifier NCT04008446 on June 17, 2019.

Multiphysics Modeling of Electrode Dissolution Under Hydrodynamic Conditions in Low Conductivity Water

Efficient plug-flow electrochemical reactors are characterized by their ability to effectively convert species with significant ionic strength and/or with the assistance of a well-behaved electrolyte. Because of the classic electroconductivity requirement, electrochemical reactors are not particularly attractive options for applications with low-conductivity conditions, especially for low-pressure feeds. However, these reactors can still find application in dedicated processes such as ultra-clean water conditioning and biological-coupled separation systems. Consequently, a multi-physics model was developed using COMSOL Multiphysics to characterize different reactor-design conditions based on the Tertiary Current Distribution which accounts for the effects of expected variations in electrolyte composition and ionic strength on the electrochemical process, as well as solution resistance and electrode kinetics. The modelling framework presented here employs single-phase laminar fluid flow, the Nernst-Planck equation, the water-based electroneutrality condition, and concentration-dependent overpotentials. This investigation particularly explores the electrolysis process of “anodic dissolution,” in which elemental species dissociate from the solid matrix of the electrode and enter the liquid phase of the electrolyte as soluble ions. The reactor configuration of interest has a rectangular parallel-electrode design and is operated galvanostatically. A series of parametric studies are carried out to inspect the response of the system when hydrodynamic, kinetic, and geometric conditions are changed. The parametric sweep resulted in variable effluent concentrations and system voltage, which reveal underlaying optimization patterns for electrode dissolution in low conductivity water.

Conscious Sedation Using Nitrous Oxide and Midazolam for Dental Procedures in Pediatric Patients in Armed Forces Hospital – Our Experience

Abstract Background and Aim: Management of pain and anxiety associated with dental procedures in pediatric age group is a big challenge. In this part of the world, counselling has been the main modality for managing such patients. It is associated with mixed outcome. We share our experience of managing 23 patients using a combination of inhalational nitrous oxide- oxygen and intravenous midazolam with satisfactory outcomes. Material and Methods: Patients aged more than six years, American society of anaesthesiologists classification (ASA) I or II, procedure that could be finished within one hour like pulpectomies, root canal treatments, extraction and multiple restorations were accepted for conscious sedation. Complete blood count was done and pre-anaesthetic checkup (PAC) with written informed consent from the parent was taken for the dental procedure under conscious sedation. We placed the nasal mask of the Conscious sedation anesthesia machine and made the child inhale Oxygen/Nitrous oxide mixture. After inhaling variable concentration of nitrous oxide/ oxygen mixture in proportion increasing from 30:70 to 70:30, procedure was done. After completion of the procedure, the patient was administered hundred percent oxygen for five minutes. Results: We have done a total of twenty-three cases till now with ages between five to seventeen years. The duration of procedures ranged from 30 min to one and half hour. Two patients less than six years were found to be uncooperative for the procedure. Conclusion: Minimum age group that was suitable for conscious sedation was six years and above. Frequent meetings and counselling by the same team should be facilitated prior to taking up for the procedure.

Application of a Novel Dissolution Medium with Lipids for In Vitro Simulation of the Postprandial Gastric Content.

Food can change various physiological parameters along the gastrointestinal tract, potentially impacting postprandial drug absorption. It is thus important to consider different in vivo conditions during in vitro studies. Therefore, a novel dissolution medium simulating variable postprandial pH values and lipid concentrations was developed and used in this study. Additionally, by establishing and validating a suitable analytical method, the effects of these parameters on the dissolution of a model drug, cinnarizine, and on its distribution between the lipid and aqueous phases of the medium were studied. Both parameters, pH value and lipid concentration, were shown to influence cinnarizine behavior in the in vitro dissolution studies. The amount of dissolved drug decreased with increasing pH due to cinnarizine's decreasing solubility. At pH values 5 and 7, the higher concentration of lipids in the medium increased drug dissolution, and most of the dissolved drug was distributed in the lipid phase. In all media with a lower pH of 3, dissolution was fast and complete, with a significant amount of drug distributed in the lipid phase. These results are in accordance with the in vivo observed positive food effect on cinnarizine bioavailability described in the literature. The developed medium, with its ability to easily adjust the pH level and lipid concentration, thus offers a promising tool for assessing the effect of co-ingested food on the dissolution kinetics of poorly soluble drugs.

Dysregulated serum concentrations of fat-soluble vitamins in dogs with chronic enteropathy.

In inflammatory bowel disease (IBD) of humans, nutrient malabsorption can result in fat-soluble vitamin deficiency, especially of vitamin D. In veterinary species, decreased concentrations of vitamin D are relatively common in dogs with chronic enteropathy (CE), but data on the status of other fat-soluble vitamins (FSVs) is lacking. Determine the serum concentrations of retinol, vitamin D, and α-tocopherol in dogs with CE compared with healthy dogs and compare clinical, clinicopathologic variables between CE and healthy dogs to detect associations with decreased FSVs concentrations. Eighteen client-owned dogs with CE and 33 healthy dogs. Serum 25-hydroxyvitamin D (25[OH]D), serum retinol and α-tocopherol concentrations were compared between groups. Correlations and multiple regression modeling were used to examine the relationship between serum 25(OH)D, retinol, and α-tocopherol concentrations and clinical and clinicopathological variables. Dogs with low serum albumin concentrations were more likely to have lower 25(OH)D concentrations than dogs with normal serum albumin concentration. Dogs with CE had higher serum concentrations of retinol, and variable α-tocopherol concentrations. The cause of these dysregulated vitamin concentrations is unclear and requires further study. Dogs with severe forms of CE should be monitored for decreased concentrations of 25(OH)D. Additional studies are needed to evaluate the clinical relevance and the possible benefit of vitamin D supplementation in these patients.

Supplementary rental supply? The digital market for low-cost and informal housing in Sydney, Australia

This article examines real estate platforms and the data they generate to provide new insights into housing markets and practices, focusing on lower-cost and informal sectors, where building or rental regulations are often bypassed or contravened. We examine online listings advertised in Sydney, one of the most expensive cities in Australia and the world, compiling data from four dominant platforms – Realestate.com.au, Flatmates.com.au, Gumtree.com.au and Airbnb.com – each of which offers a particular type of rental accommodation. Using these datasets, we identify a typology of lower-cost and informal tenures and dwelling units, ranging from secondary dwellings and illegally subdivided apartments to shared accommodation and precarious rental agreements. Our study highlights a supplementary supply of rental housing, operating within the conventional private rental market, accessed and made visible via the platforms we examine. Applying a statistical regression approach, we examine relationships between concentrations of informal housing supply and socio-economic variables. The findings reveal intersections between digital platforms and evolving informal market practices and have implications for urban planning and housing policy.

Adaptation of the protein misfolding cyclic amplification (PMCA) technique for the screening of anti-prion compounds.

Prion diseases result from the misfolding of the physiological prion protein (PrPC) to a pathogenic conformation (PrPSc). Compelling evidence indicates that prevention and/or reduction of PrPSc replication are promising therapeutic strategies against prion diseases. However, the existence of different PrPSc conformations (or strains) associated with disease represents a major problem when identifying anti-prion compounds. Efforts to identify strain-specific anti-prion molecules are limited by the lack of biologically relevant high-throughput screening platforms to interrogate compound libraries. Here, we describe adaptations to the protein misfolding cyclic amplification (PMCA) technology (able to faithfully replicate PrPSc strains) that increase its throughput to facilitate the screening of anti-prion molecules. The optimized PMCA platform includes a reduction in sample and reagents, as well as incubation/sonication cycles required to efficiently replicate and detect rodent-adapted and cervid PrPSc strains. The visualization of PMCA products was performed via dot blots, a method that contributed to reduced processing times. These technical changes allowed us to evaluate small molecules with previously reported anti-prion activity. This proof-of-principle screening was evaluated for six rodent-adapted prion strains. Our data show that these compounds targeted either none, all or some PrPSc strains at variable concentrations, demonstrating that this PMCA system is suitable to test compound libraries for putative anti-prion molecules targeting specific PrPSc strains. Further analyses of a small compound library against deer prions demonstrate the potential of this new PMCA format to identify strain-specific anti-prion molecules. The data presented here demonstrate the use of the PMCA technique in the selection of prion strain-specific anti-prion compounds.

Austenite formation and solute redistribution during double soaking of a 7Mn-steel

In this work, the influence of secondary soaking parameters on microstructural evolution in medium manganese steels is evaluated with a specific focus on the mechanisms driving austenite formation and solute partitioning at an intermediate secondary soaking temperature of 750 °C. The secondary soaking heat treatment represents the latter step of the double soaking heat treatment where it is used, after an initial intercritical annealing heat treatment, to form additional, solute-lean austenite. Here, data are obtained on a 0.14C-7.17 Mn steel for secondary soaking temperatures between 700 °C and 800 °C, and for times up to 1200 s. Austenite formation during secondary soaking is characterized using dilatometry and XRD, while Mn redistribution is experimentally observed using STEM-EDS. Manganese partitioning during secondary soaking, as well as calculated changes in carbon partitioning, are further explored through a DICTRATM model. Experimental and simulation results suggest that the ferrite-to-austenite transformation during the secondary soaking step may proceed under a partitioning, diffusional transformation at the 750 °C secondary soaking temperature. Manganese partitioning was demonstrated to primarily occur from ferrite to newly formed secondary austenite, while carbon diffusion principally occurred from primary to secondary austenite. Transformation of secondary austenite to martensite upon quenching along with some fraction of primary austenite, whose transformation was attributed to a reduction in C concentration, was shown demonstrated. The results of this study are expected to be of interest to those seeking to design multi-step heat treatments which produce austenite of variable solute concentrations and stabilities.

Comparison of modeling methods for the effective diffusivities of IO3 − estimated in compacted bentonite using through-diffusion tests under aerobic conditions

Abstract Diffusion is the predominant mechanism governing the transport of 129I through geosphere. Consequently, the assessment of the experimental findings on two-compartment diffusion reservoirs of IO3 − within compacted bentonite involved the application of three distinct diffusion models: CC–CC (constant concentration), CC–VC (variable concentration), and VC–VC. To ensure the reliability of the obtained diffusion coefficients, multiple laboratory tests were performed for internal comparison. The experimental results revealed that IO3 − diffusion coefficients were ranging from 3.83 × 10−13 to 1.91 × 10−11 m2/s. These techniques using three mathematical models could be conducted to estimate the diffusion coefficients of non- or weakly-sorbing radionuclides on compacted bentonite for safety assessment of radioactive waste final disposal.

Impact of wastewater treatment and drought in an Alpine region: a multidisciplinary case study

In the context of global climate change, drought occurrence in streams of alpine origin is a recent phenomenon, whose impact is still poorly investigated. In this study, we adopted a three-disciplinary approach to investigate the response of an Alpine river (NW Italy) to severe drought conditions occurred in the year 2022. We hypothesised that the considerable loss in the water flow could exacerbate wastewater treatment plant (WWTP) discharge effects, lowering dilution capacity of the stream system and then increasing chemical/microbial pollution and altering benthic community characteristics. To assess river response to drought conditions of the considered year, the concentration of the main chemical variables, faecal indicator bacteria, pathogen presence and structural/functional organisation of benthic macroinvertebrates and diatom communities were measured monthly in the reaches located upstream and downstream of a WWTP (January–December 2022). Main environmental variables, such as flow velocity, water depth, and flow regime, were also considered. A multivariate analysis approach was then applied to emphasise correlations between selected variables and flow regime.Comparing upstream and downstream sections over the considered year, a common behaviour of chemical/microbiological parameters was observed, with generally higher concentrations of nutrients and bacterial indicators downstream of the local WWTP. Moreover, a positive correlation between water scarcity and nutrients/bacterial concentrations was revealed. The macroinvertebrate communities responded accordingly, both in terms of density and biological metric shift.Interestingly, differences between the two sections were strictly associated with hydrological conditions, with higher dissimilarities found in low-flow conditions. As the magnitude and duration of drought events are projected to increase in the years to come in different parts of Europe, this work can serve as a first building block and as a hint for future studies aimed at improving our knowledge about the consequences of these events that is pivotal for planning effective management strategies.

Critical Mineral Separations: Opportunities for Membrane Materials and Processes to Advance Sustainable Economies and Secure Supplies.

Sustainable energy solutions and electrification are driving increased demand for critical minerals. Unfortunately, current mineral processing techniques are resource intensive, use large quantities of hazardous chemicals, and occur at centralized facilities to realize economies of scale. These aspects of existing technologies are at odds with the sustainability goals driving increased demand for critical minerals. Here, we argue that the small footprint and modular nature of membrane technologies position them well to address declining concentrations in ores and brines, the variable feed concentrations encountered in recycling, and the environmental issues associated with current separation processes; thus, membrane technologies provide new sustainable pathways to strengthening resilient critical mineral supply chains. The success of creating circular economies hinges on overcoming diverse barriers across the molecular to infrastructure scales. As such, solving these challenges requires the convergence of research across disciplines rather than isolated innovations.

Anthropogenic Drivers of Spatial Trends in Groundwater Quality in the Upper Athi River Basin of Kenya, East Africa

Rapid urbanization and population growth in the upper Athi River basin in Kenya have increased the strain on the sub catchments water supply and sanitation situation. Due to increasing demand, inadequate supply of drinking water and lack of sanitation facilities, people in the sub-catchment are increasingly reliant on groundwater as a primary or supplementary water source. However, the use of on-site wastewater systems and agricultural pollution, mainly from runoff containing fertilizers, pesticides, herbicides, and faeces, pose a threat to groundwater in the sub catchment. Subsequently, the current study was conducted in the Thiririka sub catchment, Kiambu County, Kenya, to determine the safety of groundwater sources and to examine the factors influencing groundwater quality in the catchment area. This study assessed the influence of anthropogenic activities on the physical, chemical, and bacteriological quality of groundwater in the Upper Athi River basin of Kenya between April and June 2022. Twenty variables were analyzed and compared with water quality standards to determine hydro chemical characteristics, evidence of contamination, and suitability of groundwater. Shallow wells (SW) had higher concentrations of major ions and key parameters than boreholes (BH), such as alkalinity (7%), turbidity (96%), nitrates (92%), sulfates (48%), phosphates (93%), chlorides (77%), potassium (84%), sodium (30%) and fecal coliforms (99%) significant at p < 0.01. Concentrations of eleven water quality variables however were comparable in both systems. Farming, animal husbandry, and pit latrines were negatively but significantly correlated with the water quality of SW explaining substantial amounts of variation (≤ 45%) in concentrations of water quality variables. Ionic and coliform levels increased with decreasing distance and vice versa. IDW interpolation maps were generated in ArcGIS software to determine the spatial variability of groundwater quality in the basin. Anthropogenic activities such as pit latrines and animal husbandry impaired the quality of groundwater which in most cases was not potable.