Variation Of Concentration Research Articles

Coupled model on the variation of diffusion coefficient and surface chloride concentration in reinforced concrete structures over time

Durability analyses and service life estimates of structures in a marine environment can be developed through the modeling of chloride concentration profiles. However, as surface chloride concentration and diffusion coefficient vary over time, especially due to the cement hydration process, modeling chloride profiles from structures with recent degradation ages requires an adjustment for the temporal dependence of these two physical parameters. The variation of the surface chloride concentration (Cs) as a function of time tends to show an increasing asymptotic behavior, while the diffusion coefficient (D) has a decreasing asymptotic tendency. For this reason, the power function, usually used to describe the diffusion coefficient, has problems for advanced ages, while the exponential function has difficulties at recent ages. Therefore, the key issue in this problem is the rate of change of Cs and D over time. This article presents the development of a single time-dependence model to simultaneously describe the decrease in D and the increase in Cs over time. The coupled model is a piecewise-defined function, with continuity of the function and its first derivative in the transition time between recent ages and more advanced ages, defined as 10 years. To validate the new model, data from structures under natural degradation were used. The results demonstrated the applicability of the coupled model with individual adjustments of the exponent α, which implicitly represents material properties and environmental parameters. However, in the absence of sufficient information, a standard α exponent of 0.25 per year can be adopted, demonstrating a moderate to strong adherence of the coupled model to the Cs and D data over time. Three stages of temporal dependence were identified: I – up to 10 years: marked increase in Cs and decrease in D over time; II – between 10 and 25 years: decrease in the variation rate of Cs and D; and III – from 25 years: stabilization of Cs and D.

Selective Synthesis of Defect-Rich LaMnO3 by Low-Temperature Anion Cometathesis.

The synthesis of complex oxides at low temperatures brings forward aspects of chemistry not typically considered. This study focuses on perovskite LaMnO3, which is of interest for its correlated electronic behavior tied to the oxidation state and thus the spin configuration of manganese. Traditional equilibrium synthesis of these materials typically requires synthesis reaction temperatures in excess of 1000 °C, followed by subsequent annealing steps at lower temperatures and different p(O2) conditions to manipulate the oxygen content postsynthesis (e.g., LaMnO3+x). Double-ion exchange (metathesis) reactions have recently been shown to react at much lower temperatures (500-800 °C), highlighting a fundamental knowledge gap for how solids react at lower temperatures. Here, we revisit the metathesis reaction, LiMnO2 + LaOX, where X is a halide or mixture of halides, using in situ synchrotron X-ray diffraction. These experiments reveal low reaction onset temperatures (ca. 450-480 °C). The lowest reaction temperatures are achieved by a mixture of lanthanum oxyhalide precursors: 2 LiMnO2 + LaOCl + LaOBr. In all cases, the resulting products are the expected alkali halide salt and defective La1-ϵMn1-ϵO3, where ϵ = x/(3 + x). We observe a systematic variation in defect concentration, consistent with a rapid stoichiometric local equilibration of the precursors and the subsequent global thermodynamic equilibration with O2 (g), as revealed by computational thermodynamics. Together, these results reveal how the inclusion of additional elements (e.g., Li and a halide) leads to the local equilibrium, particularly at low reaction temperatures for solid-state chemistry.

THE ETHANOL EXTRACT OF JUKUT PENDUL (KYLLINGA NEMORALIS) EXHIBITS INHIBITORY ACTIVITY AGAINST THE GROWTH OF STAPHYLOCOCCUS AUREUS

Staphylococcus aureus is a pathogenic bacteria that is often found to have resistance to antibiotics. Jukut pendul (Kyllinga nemoralis) extract is known to have antibacterial compounds such as flavonoids, tannins, saponins, and steroids. The purpose of this study was to determine the inhibitory ability of jukut pendul ethanol extract against Staphylococcus aureus bacteria. This research used the Kirby-Bauer disc diffusion method with five treatments within five repetitions. Data analysis was carried out using One Way Anova variance analysis. The variation in extract concentration tested was 5, 10, 20, and 40% with 96% ethanol as the control group and Ciprofloxacin as the work control. The results showed that extract concentrations of 5, 10, 20, and 40% were able to inhibit Staphylococcus aureus bacteria with an average inhibitory zone of 9,36; 10,85; 11,64; and 12.15 mm, respectively. The inhibitory zone formed indicates that jukut pendul ethanol extract has moderate to strong inhibitory ability in inhibiting the growth of Staphylococcus aureus bacteria.

Myocardial infarction protective effect of xyloglucan on Drosophila melanogaster: A review

Myocardial infarction, more often known as cardiac arrest, occurs when the supply of blood to the heart’s coronary artery decreases or ceases, causing damage to the heart muscle. Xyloglucan is a plant polysaccharide. Xyloglucan has been proven in several studies utilizing model organisms to reduce the risk of coronary heart disease by avoiding post-occlusion phases inhibiting apoptosis and enhancing energy metabolism. Many studies utilize Drosophila melanogaster because its SRY-related HMG-box 5 (SOX5) gene encodes a SOX family transcription factor; the human SOX5 ortholog, Sox102F, is well conserved in Drosophila melanogaster. Suppressing Sox102F in flies resulted in significant heart dysfunction, structural defects, and a disturbance in notch signal transduction. This demonstrates that SOX5 serves an important functional part in the heart and that variations in SOX5 concentrations may contribute to the possibility of myocardial infarction. Xyloglucan activity is significant in myocardial infarction and may be lowered in the myocardium after H/R damage by stimulating Notch signaling, which may benefit myocardial survival, angiogenesis, and cardiac function. This review discusses the roles of the human SOX5 and Drosophila SOX102F genes, the notch signaling system, and how xyloglucan in tamarind seeds may defend against heart damage by preventing apoptosis along with improving energy metabolism.

Calcium Signaling and the Response to Heat Shock in Crop Plants.

Climate change and the increasing frequency of high temperature (HT) events are significant threats to global crop yields. To address this, a comprehensive understanding of how plants respond to heat shock (HS) is essential. Signaling pathways involving calcium (Ca2+), a versatile second messenger in plants, encode information through temporal and spatial variations in ion concentration. Ca2+ is detected by Ca2+-sensing effectors, including channels and binding proteins, which trigger specific cellular responses. At elevated temperatures, the cytosolic concentration of Ca2+ in plant cells increases rapidly, making Ca2+ signals the earliest response to HS. In this review, we discuss the crucial role of Ca2+ signaling in raising plant thermotolerance, and we explore its multifaceted contributions to various aspects of the plant HS response (HSR).

Cu2Te/CoTe nanoparticles with tuneable bandgaps: Implications for photovoltaic and optoelectronic devices

Herein, we report the structural, optical, and electrochemical response of Cu2Te/CoTe nanoparticles synthesized by the facile microwave synthesis method by varying Cu and Co concentrations. Various characterizations such as Rietveld-refined X-ray diffraction, Raman Spectroscopy, and Transmission electron microscopy analysis infer the two hexagonal phases Cu2Te and CoTe having space group p6/ mmc and P63/ mmc, respectively. The elemental Energy-dispersive X-ray and X-ray photoelectron spectroscopy confirm the composition of all the elements. Field emission scanning electron microscopy images exhibit nanoparticles that remain unaltered even after the essential concentration variation. However, the differential scanning calorimetry study analyses the phase change of the material from room temperature to higher temperatures. Meanwhile, from UV-Vis spectroscopy, the optical band gap increases, and the refractive index value decreases in both the cases, Tauc plot, as well as Kubelka-Munk plot by varying Cu and Co concentrations, which shows well-defined properties that enable the material for various solar cell and optoelectronic applications. In addition, the electrochemical impedance spectroscopy analysis of the as-prepared material reveals small kinetic at high-frequency regions that can be used as the charge transfer of the electrode-electrolyte interface. The tuneable structural, optical, and electrochemical response of the CuCoTe nanomaterial broadens the advanced optoelectronic application prospects.

Seasonal variation in metals concentration associated with settled dust and their risk assessment in school children of Agra (India)

Metals associated with indoor dust are shown to be a key pollutant and resuspension of dust in critical microenvironments like schools can lead to detrimental health effects to children. The present study was carried out from December 2021 to November 2022 to examine variations in metal concentration with season and associated health risks from school dust in Agra, India. Dust samples were digested in aqua-regia followed by analysis for metals concentration by ICP-AES. Geo-accumulation (Igeo), pollution (PI), integrated pollution (IPI), and pollution load (PLI) indexes were used to determine metals contamination, Principal Component Analysis and Cluster Analysis were employed for the identification of causative sources of metals while USEPA health risk assessment models were utilized to assess the health risks in children. The results indicated that in all seasons settled dust of roadside schools of both regions accumulated higher concentrations of metals as compared to residential schools except semi-urban schools in post-monsoon season. The total metal concentration (mgkg−1) in school dust samples of Agra ranged from 62507–85037, 72477–97022, 48912–66083 to 58605–92290 in winter, summer, monsoon, and post-monsoon respectively. In all seasons, the PLI values of settled dust of all schools ranged from less than one to greater than unity which indicates pollution levels by metals. Further, Igeo values revealed that school dusts were moderately and heavily contaminated by Cd in all seasons. The assessment of health risk specifies ingestion as the main exposure route followed by dermal intake and inhalation. The Hazard Index value for all examined metals was lower than the safer limit of one while on the contrary for Pb, total cancer risk was higher the than safer limit via inhalation pathway. The findings of the study indicate that more investigations are required on potentially toxic metal contaminations in schools of Agra, especially for Pb, Cd and Cr.

Long-term response of the microbial community to the degradation of DOC released from Undaria pinnatifida

With the aim to study the mechanism underlying the macroalgal carbon sequestration driven by microbes, we investigated the microbial community using metagenomics methods and its long-term degradation of dissolved organic carbon (DOC) derived from Undaria pinnatifida. It was observed that after removing U. pinnatifida, the concentration of the DOC decreased significantly (p < 0.05) within 4 days. Over a period of 120 days of degradation, the concentration of remaining DOC (26%) remained stable. The succession of microbial community corresponded to the three stages of DOC concentration variation. Moreover, the structure of microbes community and its metabolic function exhibited evident patterns of succession. The concentration of DOC was correlated negatively with the abundances of Planctomycetaceae (p < 0.01), and was correlated positively with the abundances of Roseobacteraceae and Rhodobacteraceae (p < 0.01). In addition, the metabolic pathways related to “Glycolysis/Gluconeogenesis”, “Alanine, aspartate, and glutamate metabolism”, “Citrate cycle (TCA cycle)” and “Tryptophan metabolism” was significantly correlated with the variations in DOC concentration (p < 0.05). These findings indicate that the variation in the DOC concentration was closely linked to the succession of Planctomycetaceae, Roseobacteraceae, Rhodobacteraceae, and the degradation of DOC derived from U. pinnatifida appeared to be influenced by metabolic functions.

Antimicrobial Activity Of Mouthwash Ethanol Extract of Curcuma purpurascens Bl. (Temu Blenyeh) as Affected by Sodium Lauryl Sulfate Concentration Variations

Oral and dental health problems are usually caused by pathogenic microbes such as Streptococcus mutans and Candida albicans. Sodium lauryl sulfate is a foamer that can remove microorganisms in the oral cavity. Using mouthwash is considered the easiest and most effective because it can reach between the teeth. Therefore, the aim of this research is to create and see the effect of varying the concentration of sodium lauryl sulfate in mouthwash preparations of ethanol extract of temu blenyeh (Curcuma purpurascens Bl.) on inhibiting the growth of microbes such as Streptococcus mutans and Candida albicans. The results of testing the antimicrobial activity of mouthwash preparations against Streptococcus mutans bacteria were classified as very weak in formulation (0), namely 3.00 mm, then in the medium category, namely in formulation (I) 5.30 mm, formulation (II) 6.66 mm, and formulation (III) 10.33 mm, while the fungus Candida albicans is classified as very weak in formulation (0), namely 4.00 mm. Then it is classified as medium with an average diameter of the inhibition zone, namely formulation (I) of 5.53 mm, formulation (II) of 8.00 mm, and formulation (III) of 8.58 mm. From these results, it can be concluded that there is an effect of using varying concentrations of sodium lauryl sulfate in each formula on the antimicrobial activity of Streptococcus mutans and Candida albicans.

Atmospheric Nitrogen Pollution Control Benefits the Coastal Environment.

Nitrogen is an essential nutrient and a major limiting element for the ocean ecosystem. Since the preindustrial era, substantial amounts of nitrogen from terrestrial sources have entered the ocean via rivers, groundwater, and atmospheric deposition. China serves as a key hub in the global nitrogen cycle, but the pathways, sources, and potential mitigation strategies for land-ocean nitrogen transport are unclear. By combining the CHANS, WRF-Chem, and WNF models, we estimated that 8 million tonnes (Tg) of nitrogen was transferred into the ocean in 2017 in China, with atmospheric deposition contributing 1/3. About half variation of the offshore chlorophyll concentration was explained by atmospheric deposition. The Bohai Sea was the hot spot of nitrogen input, estimated at 214 kg N ha-1, while other areas were around 25-51 kg N ha-1. The largest contributors are agricultural systems (4 Tg, 55%), followed by domestic sewage (2 Tg, 21%). Abatement measures could reduce nitrogen export to the ocean by 43%, and mitigating ammonia and nitrogen oxide emissions accounts for 33% of this reduction, highlighting the importance of addressing air pollution in resolving ocean pollution. The cost-benefit analysis suggests the priority of nitrogen reduction in cropland and transport systems for the ocean environment.

Variation in urban snow quality indicated by three seasonal sampling surveys conducted in Luleå (Sweden) within a span of 27 years

Concentrations of total suspended solids (TSS), trace metals (Cu, Cd, Cr, Zn, Cd, Pb), Na and 16 US EPA priority PAHs in urban snow were studied in the City of Luleå in Northern Sweden. Snow was sampled at six central urban and suburban sites with various traffic intensities, in three sampling surveys (1994–95, 2002–03, 2020–21), repeated for three ages of the urban snow cover of 40, 80, and 120 days, respectively. The older data, from the 1994–95 and 2002–03 surveys, were obtained from the existing literature. The concentrations and mass loads of TSS and most trace metals studied (Zn, Cu, Pb, and Cd) varied with time. TSS, Zn, and Cu showed slightly higher concentrations and mass loads in the 2003 (TSS avg = 2300 μg/L, Zn avg = 620 μg/L and Cu avg = 250 μg/L) and 2021 (TSS avg = 1500 μg/L, Zn avg = 530 μg/L and Cu avg = 220 μg/L) sampling surveys, compared to the 1995 survey (TSS avg = 620 μg/L, Zn avg = 240 μg/L and Cu avg = 97 μg/L). However, no evident trend was observed between the 2003 and 2021 sampling surveys. The highest concentrations of Pb and Cd were observed in snow samples from the 1994–95 sampling survey (Pb max = 570 μg/L, Cd max = 4.6 μg/L). Results indicated higher concentrations of the pollutants studied in the city centre, compared to the residential suburbs, and in areas with heavier traffic, where concentrations of metals correlated well with traffic intensity. Fractionation analysis of trace metals indicated that Zn, Cu and Pb occurred mostly in the particulate-bound phase (>0.45 μm) containing the most of Zn, Cu, and Pb mass, at 80, 84 and 94% of the total, respectively. Over 50% of the dissolved phase of Zn and Cu was in the truly dissolved fraction (<3000 MWCO). Concentrations of PAHs also increased with traffic intensity, with pyrene being the most frequently detected PAH, likely because of the strength of sources and various physical processes influencing the snowbanks development and causing spatial and temporal variations in pollutant concentrations.

Exploring the Utility of Urinary Creatinine Adjustment for KIM-1, NGAL, and Cystatin C for the Assessment of Kidney Function: Insights from the C-KidnEES Cohort.

Normalization of urinary biomarkers of kidney injury is a common practice in clinical and research settings to account for variations in urine concentration, and urinary creatinine is often used as a reference. However, to date, there is no consensus on the adjustment of urinary biomarkers with creatinine, and both absolute and creatinine-adjusted biomarker levels are adopted for making interpretations of kidney health. Hence, the present study aimed to investigate the associations of urinary creatinine with three widely used kidney injury biomarkers, KIM-1, NGAL, and cystatin C, to validate the applicability of urinary creatinine as a reference for normalization. A cross-sectional study was performed with 2100 students, 10-18 years of age in the Children's Kidney Environmental Exposure Study (C-KidnEES) cohort established in Sri Lanka. As identified in linear regression analyses, normalization of urinary KIM-1, NGAL, and Cys-C to urinary creatinine did not result in significant under-adjustment or over-adjustment to the absolute urinary concentrations, giving no specific rationale for creatinine adjustment. Hence, absolute urinary concentrations of the above biomarkers can be adopted for the characterization of subclinical kidney injury in adolescents in community studies where early morning urine sampling is practiced. However, for spot urine samples, consideration of both absolute and creatinine-adjusted biomarker levels would be a better approach.

Influence of tobacco product wastes in a protected coastal reserve adjacent to urbanization

The present study, conducted at the Kendall-Frost Mission Bay Marsh Reserve in San Diego, California, aimed to assess tobacco-related pollutants in urban waters, a topic with limited prior research. Across 26 events occurring between November 2019 and February 2022, encompassing both wet and dry seasons at two outfall sites (Noyes St. and Olney St.), water and sediment samples were subjected to analysis for nicotine and cotinine levels, with Noyes St. displaying wide variation in nicotine concentrations, reaching a peak of 50.75 ng/L in water samples, whereas Olney St. recorded a peak of 1.46 ng/L. Wet seasons consistently had higher nicotine levels in water, suggesting the possibility of tobacco litter entering the reserve through stormwater runoff. Cotinine was detected in both sites in both water and sediment samples; however, these levels were considerably lower in comparison to nicotine concentrations.Limited research assesses aquatic environmental pollution from tobacco use and disposal, especially in protected areas like urban natural reserves. This study was conducted at the Kendall-Frost Mission Bay Marsh Reserve in San Diego, California, to evaluate tobacco-related pollutants in San Diego's urban waters. Twenty-six sampling events between November 2019 and February 2022, spanning wet and dry seasons at two outfall sites, were conducted. Nicotine and cotinine, a major ingredient of tobacco and its metabolite, were analyzed in the collected water and sediment samples. Nicotine concentrations differed substantially between the outfall locations (Noyes St. and Olney St.), with Noyes St. displaying wide variations, averaging at 9.31 (±13.24) ng/L with a maximum concentration of 50.75 ng/L, and Olney St. at 0.53 (±0.41) ng/L with a maximum concentration of 1.46 ng/L in water samples. In both locations, the nicotine concentrations in water samples were higher during wet seasons than dry seasons, and this pattern was more significant at Noyes St. outfall than at Olney St. outfall, which received not only stormwater runoff but also was connected to Mission Bay. Although this pattern did not directly align with sediment nicotine levels at both sites, maximum nicotine concentration in Noyes St. sediments during wet seasons was approximately 120 times higher than in Olney St. sediments. Regarding cotinine, Noyes St. outfall water averaged 3.17 ng/L (±1.88), and Olney St. water averaged 1.09 ng/L (±1.06). Similar to nicotine, the cotinine concentrations were higher in Noyes St. water and sediment compared to Olney St., but overall, the cotinine concentrations in both water and sediment were much lower than the corresponding nicotine concentrations. The study identifies urban stormwater runoff as a potential source of nicotine and cotinine pollution in a protected reserve, implicating tobacco product litter and human tobacco use as contributing factors.

Effect of the “K” technique on levels of anxiety and salivar cortisol in adolescents

This research presents theoretical arguments of a new approach called Technique “K,” which aims to reduce student’s anxiety before a cognitive challenge. Through a randomized, controlled clinical trial, we evaluate the Beck Anxiety Inventory and salivary cortisol. We compared the results in the last year of high school, who were facing school tests, before and after the application of the “K” technique (intervention group) and placebo (control group). Statistical analyses consisted of using the Chi-square, Spearman and the Wilcoxon test. The principal component analysis observed in the case group, - 10.50 (-18.25; -4.75), was statistically higher than the control group, -6.00 (-8.75; -1.25). It is not possible to identify statistical significance (p = 0.462) in the variation of salivary cortisol concentration. The results suggest the effectiveness of the “K” technique in managing anxiety in high school students. Although, future research is needed to extend the preliminary data obtained in this study.

Nanoparticle ranking analysis: determining new particle formation (NPF) event occurrence and intensity based on the concentration spectrum of formed (sub-5 nm) particles

Abstract. Here we introduce a new method, termed “nanoparticle ranking analysis”, for characterizing new particle formation (NPF) from atmospheric observations. Using daily variations of the particle number concentration at sizes immediately above the continuous mode of molecular clusters, here in practice 2.5–5 nm (i.e. ΔN2.5−5), we can determine the occurrence probability and estimate the strength of atmospheric NPF events. After determining the value of ΔN2.5−5 for all the days during a period under consideration, the next step of the analysis is to rank the days based on this simple metric. The analysis is completed by grouping the days either into a number of percentile intervals based on their ranking or into a few modes in the distribution of log (ΔN2.5−5) values. Using 5 years (2018–2022) of data from the SMEAR II station in Hyytiälä, Finland, we found that the days with higher (lower) ranking values had, on average, both higher (lower) probability of NPF events and higher (lower) particle formation rates. The new method provides probabilistic information about the occurrence and intensity of NPF events and is expected to serve as a valuable tool to define the origin of newly formed particles at many types of environments that are affected by multiple sources of aerosol precursors.

Challenges of Scaling-up the Wet-Chemical Synthesis of β-Li3PS4

All-solid-state batteries are considered the next generation in battery technology due to increased energy and power density as well as freedom of design, e.g. by constructing batteries in bipolar stacks. Solid-state electrolytes offer advantages over conventional liquid electrolytes, such as greater thermal safety, because of high melting points, and higher mechanical strength. This is believed to suppress growth of lithium dendrites and, therefore, opens up the possibility of using a lithium metal anode. One promising material group is sulfides, because they are ductile and have a good intrinsic ionic conductivity. Some sulfide solid electrolytes can be synthesized wet-chemically. This offers advantages like tailoring the particle size, working at ambient temperatures, short synthesis durations, stabilizing meta-stable phases by using new synthesis routes and the possibility of transferring the routine to a continuous process. The particle size and morphology are important factors regarding the suitability to produce all-solid-state batteries wherefore small (< 10 µm) and homogeneous particles are preferred. The present research mainly focusses on finding and improving new materials and their usage in battery production, but there is little progress on mass-production of sulfide solid electrolytes. To scale-up a synthesis, multiple aspects have to be considered since they often influence both product and process. Therefore, an analysis and optimization of the synthesis process is necessary to support the development and to increase the economic attractiveness of new materials.In this presentation, the reaction enthalpy and the influences of concentration and solvent variation of synthesizing the sulfide solid electrolyte β-Li3PS4 are examined and discussed. β-Li3PS4 is synthesized by mixing lithium sulfide and phosphorus pentasulfide in a solvent, e.g. THF, at ambient conditions. After removing the solvent, heat treatment is used to obtain the crystalline product. We found that the mixing step contains a highly exothermic reaction and determined the reaction enthalpies using a reaction calorimeter. To handle the heat development, two options were investigated: First, the solvent amount was increased and second, the synthesis was performed using alternative solvents with different thermal properties. The examined solvents are THF, ethyl acetate and ethyl propionate. The reaction enthalpies of the synthesis in different solvents are compared. A strong influence on the particle size and morphology caused by the amount and choice of solvent could be detected by SEM. While the particle size increases with increasing amount of solvent, the shape of the particles alters under solvent variation. With low solvent amount the smallest particle sizes (< 10 µm) are synthesized. Finally, suggestions regarding the scale-up will be given based on the findings of these examinations.

Electrodialysis of Lithium Sulfate Solutions from Hydrometallurgical Recycling of Spent Lithium-Ion Batteries

Recycling lithium-ion battery materials is a crucial step to achieving a circular economy. A hydrometallurgical recycling process of spent lithium-ion battery materials involves leaching by acids and precipitation by bases. A large amount of Li2SO4 leachate solution is generated at the end of the recycling process. Such Li2SO4 solution can be separated by electrodialysis (ED) to form H2SO4 and LiOH solutions, which are reused for leaching and precipitation, respectively, making the recycling a closed-loop process. In this study, an ‘electrodialysis stack constructed with bipolar membranes’ (EDBM) is built with repetitive unit cells consisting of a bipolar membrane, anion exchange membrane (AEM), and cation exchange membrane (CEM), see Fig. 1(a). The effective area for each membrane is 121.8 cm2 (70mm×174mm). The gap between these membranes is 0.8mm, with a mesh inserted to allow flow mixing. All experiments were operated at constant current mode. The feed, acid, and base solutions were recirculated through their tanks at initial concentrations of 1.1, 0.1, and 0.1 mol/L. The ion concentrations of the solutions were measured with Inductively coupled plasma mass spectrometry periodically. The weight and the pH value of the solution tanks were also recorded.The trend of concentration variations of the present stack with up to 6 cell pairs is found to be consistent with that observed with a three-compartment configuration in our previous study [1]. The concentration of H2SO4 increases with time linearly, whereas that of LiOH levels off due to a significant electro-osmosis that drags water through the CEM into the concentrate channel. The present setup differs from the three-compartment design in the bipolar membrane, which splits water to produce H+ and OH- at the internal interface, eliminating the formation of bubbly flows in the unit cell. It is found that the voltage loss across the bipolar membrane ca. 1V accounts for a major part of the unit cell of about 1.27V.The effects of current density, number of cell pairs, and flow rates on the overall stack performance are investigated. Increasing the stack current density accelerates the separation process at the cost of higher voltage losses. It is found that increasing the number of cell pairs can improve the overall production efficiency and reduce energy consumption per cell pair. For instance, at 800 A/m2, the specific energy consumption for LiOH production is reduced to 3.40 kWh/kg with five cell pairs versus 5.83 kWh/kg with two cell pairs. It is also found that increasing the solution flow rate can result into the increase of LiOH solution concentration, ion recovery rate, and current efficiency (Fig. 1b), although the impact of flow rate is low.A small EDBM stack is constructed and tested for Li2SO4 separation in the present study. This work demonstrates that EDBM can be a simple and energy-saving alternative to the current chemical precipitation method to produce LiOH from Li2SO4. The present study provides new insights into optimal operation and design for Li2SO4 EDBM. The findings are helpful in determining how the stack can be scaled up for practical application. Furthermore, a 2D multiphysics model is currently under development to elucidate the coupled transport processes within the unit cell. The model will be validated with experimental data of the present setup. Figure 1

HfO2-Based Switching Devices with Nitridation of the Bottom Electrode

HfO2 -based Resistive Switching devices are a promising candidate for in-memory computing due to their lowpower consumption, good endurance, reliability, and compatibility with CMOS technology [1]. Controlling theoxygen vacancy (Vo) distribution near the top and bottom electrodes by selecting proper metal-dielectric-metalstack materials has impact on the performance of the device [2-3]. Significant improvement in switching poweris achieved when Vo distribution is higher near the top electrode (TE) and lower near the bottom electrode [4].Introducing nitridation treatment to the TiN bottom electrode shows a significant reduction in switching powerand superior conductance quantization with nanosecond pulse width of programing pulsed operation [5].In this work we studied different TiN bottom electrode (BE) films in the TiN/HZO/TiN MIM toinvestigate its impact of BE TiN on the switching characteristics. Fig. 1 shows schematic for the two differentswitching devices with identical top electrodes (10 nm PVD TiN) and same switching dielectric (10 nm HZO) butwith different N2 levels of 30 nm TiN at the BE. Device-B has higher level of N2 compared to device-A. Formingprocess was performed by applying DC voltage sweep with 1nA compliance current. The device-A has the lowestforming power (0.86nW) as shown in Fig. 2(a). An increase in the forming power consumption was observed fordevice-B (2.45nW) as shown in Fig. 2(b). We carried out the carrier transport characterization at the highresistance state (HRS) prior to forming process. Fig. 2(c)&(d) shows the conduction process in both devices. Indevice-A, the current conduction mechanism followed the hopping conduction in the dielectric as shown in Fig.2(c). The hopping conduction is a bulk-limited conduction mechanism depends on the electrical properties of thedielectric itself such as the trap energy level [6]. The conduction mechanism in device-B (high N2) (Fig. 2(d)) andwas dominated by the Schottky conduction in the HZO layer, which is an electrode-limited conduction thatdepends on the electrical properties at the electrode-dielectric interface [6]. When the active nitrogen atoms areintroduced to the BE, it diffuses to the dielectric due to increased concentration, then connect to the hafnium iondangling bonds as their lone-pair electrons, since the bonding energy of the Hf–N bond is very low (535eV)compared with that of the Hf–O bond (801eV) [7]. This allows a migration of Vo towards TE and reducing the Voconcentration near the BE for device-A leading to carrier hopping. On the other hand, Vo concentration near theBE is completely purged because of high nitrogen concentration (device-B) leading to Schottky conduction. Thisexplains the reduction of forming power in device-A. Fig. 3 shows the resistance distribution after applying 30DC sweeps with reading voltage of 0.1V after each sweep. The device-B (high N2) shows the largest windowbetween HRS and LRS compared to the other devices. That further confirms the forming process in these devices.In summary, low level of N2 reduces the forming power while higher level of N2 enhances the resistance windowbetween LRS and HRS because of Vo concentration variation near BE.

Leakage Diffusion Modeling of Key Nodes of Gas Pipeline Network Based on Leakage Concentration

In order to achieve the prediction and early warning of city gas pipe network leakage accidents, as well as to provide rapid and precise support for emergency response to such accidents, this study focuses on a Gaussian diffusion model applied to a large urban gas pipeline network. Specifically, it investigates the gas gate wells, which are key nodes in the pipeline network, to develop a leakage model. The objective is to analyze the variation in internal gas concentration in the gate wells and determine the range of danger posed by external gas diffusion from the gate wells. In addition, Fluent simulation is utilized to compare the accuracy of the model’s calculations. The findings of this study indicate that the gas concentration inside the gate well, as predicted by the model fitting results and Fluent simulation, exhibit a high level of agreement, with coefficient of determination (R2) values exceeding 0.99. Moreover, when predicting the hazardous distance of gas leakage outside the gate well, the model’s results show an average relative error of 0.15 compared to the Fluent simulation results. This demonstrates that the model is highly accurate and meets the practical application requirements.

Hierarchical porous triboelectric aerogels enabled by heterointerface engineering

The concept of the "Internet of Things" has made smart materials essential for sensing, responding to, and adapting to real-time feedback from the external environment. Cellulose aerogels hold immense potential in the field of smart triboelectric materials. However, conventional cellulose aerogels often face issues such as structural fragility, which limits their potential as smart materials. In this study, a compressible cellulose triboelectric aerogel with a hierarchical porous structure was prepared through heterointerface engineering. By introducing a heterointerface between oxidized cellulose nanofibers (TCNF) and carbon nanotubes (CNT), the structural stability of the material was significantly improved. The aerogel exhibited a 40-fold improvement in compressive performance and demonstrated excellent porosity (97.23%). A triboelectric nanogenerator was constructed using this material to explore its potential as a smart material. Experimental results indicated that the aerogel exhibited high sensitivity to ammonia gas, accurately identifying variations in NH3 concentration within the range of 20–150 ppm, with excellent linearity (R2 =0.996). Moreover, utilizing this triboelectric gas sensor as a wireless sensing terminal in smart devices enabled successful real-time wireless detection of food spoilage processes. This research provides new insights into the development of smart materials made from aerogels and has significant research and practical value for expanding the utilization of cellulose-based aerogels.