Chemical Water Research Articles

Religious hydro-healing and medical hydrotherapy: Links, benefits, contrasts and challenges

here seems to be some recognition of the relevance of dihydrogen oxide (water) in many spheres. Among others, literature in poetry, religious texts and medical science, address the value of water in emotional, physical and psychological healings. To understudy how religion, spirituality and medical science connect and contrast in domesticating water for healing purposes, this article undertook literary research on religious and medical hydro-healings in Christianity, African and Native American traditional religions, and medical science. It presented links, benefits, challenges and contrasts between spiritual healing and medical water therapy as well as inter-religious connections. Based on the literature, the article discovered that spiritual hydro-healing is spiritual, instantaneous and non-scientific, but medical hydrotherapy is organic, naturopathic, gradual and scientific or logical. On the positive side, the article found that indigenous spiritual knowledge is a key motivating factor in the popularity of hydro-healing practices. Whereas, on the negative, it observed the danger of the grey areas of spiritual hydro-healings which include, but are not limited to, unethical practices, commercialisation of healing waters, addiction, river baptism mortality and the quest for instantaneous hydro-healing leading to health hazards and death.Contribution: The article concluded with an urgent call to stakeholders to pay attention to the hydro-healing practices that can compromise public health and safety.

Heating and ultraviolet irradiation: Gas pressure meter-based analytical system for on-site and rapid monitoring of permanganate index (CODMn)

Permanganate index (CODMn) is one of the important indicators of surface water quality measurement. Herein, a portable analytical system was developed for on-site and rapid analysis of CODMn, organic substances in water were oxidized and transformed into gases, so that CODMn concentration was converted into a change of gas pressure signal, the pressure signal change was further detected by a gas pressure meter. Heating method and ultraviolet (UV) irradiation method were used as assisting technologies for oxidization of organic substances by acidic KMnO4, a linear range of 2–150 mg l-1 and a detectable limit of 2 mg l-1 were obtained. Those methods were further applied to the detection of CODMn in various water samples (lake waters and domestic sewage) and certified reference water samples (BWZ 6974–2016C and BWZ 7617–2016), with recoveries of 89–111 %. Among them, a portable analytical system based on UV irradiation gas pressure meter was further established and used for the analysis of CODMn in field. It is a promising analytical system/device for CODMn monitoring in field, offering advantages of low-cost, easy-operation, portability and rapidness.

Evaluation of pilot-scale drinking water treatment trains using a panel of bioassays

ABSTRACT Chemical water quality monitoring is increasingly complemented with bioassays. In this study, the performance of drinking water treatment technologies was evaluated with bioassays. CALUX reporter gene bioassays and the Ames fluctuation bioassay for mutagenicity were used to analyze the responses of raw feed water with and without a spiking mixture of organic contaminants in five different pilot-scale water treatment trains applying advanced oxidation processes, reverse osmosis and filtration with (biological) activated carbon for the preparation of drinking water. In general, CALUX responses in the spiked feed water were in the same range as in the unspiked feed water, indicating that spiking did not significantly elevate the activity measured in the feed water. This observation was in line with a calculation of the combined additive behavior of the spiking mixture using bioactivities of the spiked chemicals in analog bioassays from ToxCast. This calculation gave no indication of a measurable response in the bioassays to be expected by the spiking, except for oxidative stress. Responses in the Ames fluctuation assay in most feed water were in some cases increased by AOP and mostly removed by active concentrations. The bioassay responses demonstrate the removal of emerging chemicals with different mechanisms of action by different water treatment technologies.

Sonochemical synthesis characterization and biocompatibility studies of polymeric composites for biomedical applications

In this work the in situ synthesis of mixtures of Polymethylmethacrylate (PMMA), High Density Polyethylene (HDPE) and Polypropylene (PP) with biocompatible ceramics was carried out, using high frequency ultrasound as an energy source. Starting from calcium hydroxide and ammonium hydrogen phosphate, two different crystalline phases were obtained: hydroxyapatite (HA) and calcite (CaCO3). FTIR and XRD studies showed that for the materials prepared with HDPE, only CaCO3 was formed during the synthesis process. When Polypropylene used, mixtures of HA with CaCO3 were obtained, while for the materials synthesized with Polymethylmethacrylate, only pure HA was obtained. DSC analyses did not reveal any significant changes in the melting temperatures of HDPE and PP, nor in the glass transition temperature of PMMA with the incorporation of HA and CaCO3, in the polymeric matrices. TGA, showed that the decomposition temperatures of these materials increased with respect to those of the polymers alone, indicating a significant thermal stability. Biocompatibility tests with osteoblastic cells and Scanning Electron Microscopy (SEM) studies showed that the composites of PMMA with HA, PP with HA/CaCO3 and HDPE with CaCO3, are capable of promoting cell adhesion and proliferation mechanisms, revealing potential applications as biomaterials for bone replacement.

Preparation and characterization of β-cyclodextrin capped magnetic nanoparticles anchored on cellulosic matrix for removal of cr(VI) from mimicked wastewater: Adsorption and kinetic studies

Hexavalent Chromium (Cr(VI)) is essential in many industrial processes. However, it finds its way into water bodies, posing health problems, including lung cancer and the inhibition of DNA and RNA in biological systems. Several chemical and traditional water purification methods have been developed in the past, but most are expensive, tedious and ineffective. This study aimed to prepare and characterize a low-cost hybrid adsorbent, β-Cyclodextrin capped magnetic nanoparticles anchored on a cellulosic matrix (CNC-Fe3O4NP-CD). The characterization techniques confirmed the integration of CNCs, Fe3O4NP and CD into the prepared CNC-Fe3O4NP-CD nanocomposite adsorbent. The adsorbent was employed in batch adsorption experiments by varying adsorption parameters, including solution pH, adsorbent dosage, initial Cr(VI) concentration, and contact time. From the findings, the nanocomposite adsorbent achieved a maximum Cr(VI) removal efficiency of 97.45%, while the pseudo-second-order kinetic model best fitted the experimental data with high linear regression coefficients (R2 > 0.98). The Elovich model indicated that the adsorption process was driven by chemisorption on heterogeneous surface sites, with initial sorption rates surpassing desorption rates. These findings established that CNC-Fe3O4NP-CD presents high efficiency for Cr(VI) removal under acidic pH, offering the potential for optimization and application in real-world wastewater treatment.

Structurally similar porphyrins and porphyrazines perform differently under green or red light irradiation against non-melanoma skin tumor cells

A porphyrin (H2P) and a porphyrazine (H2Pz) and their respective zinc complexes (ZnP and ZnPz), with the substituent N-ethylpyridyl-3-yl, were synthesized and their photophysical and phototoxic properties were compared. These substances showed high solubility in water due to the cationic moieties and without notable aggregation in this solvent. Photophysical studies showed that H2P and H2Pz have fluorescence quantum yields (ΦF) of 2.04% and 0.48% in water, respectively, that, upon metalation, decreases to 1.4% for the metalloporphyrin (ZnP) and increases to 6.1% for the metalloporphyrazine (ZnPz). Regarding the singlet oxygen production efficiency (ΦΔ) of the substances in water, a considerable increase from 16.2% to 41% was obtained for the porphyrin upon coordination to zinc, while the porphyrazines practically do not produce singlet oxygen (< 1%) in this solvent. When tested against human squamous cell carcinoma cells (A-431) and immortalized human keratinocytes (HaCaT), the toxicity of all compounds increased using green (520 ± 5 nm) and red (625 ± 5 nm) radiation when compared to the non-irradiated cells, however, phototoxicity was higher for the porphyrins using green light, while the porphyrazines performed better under red radiation. Furthermore, porphyrins had a higher phototoxic index than porphyrazines and greater selectivity for A-431 cancer cells compared to HaCaT cells. To the best of our knowledge, this is the first work that compares the photophysical response and in vitro anticancer activity of porphyrins and porphyrazines with the same substituent.

Corrigendum to “Sorptive removal of per- and polyfluoroalkyl substances (PFAS) in organic-free water, surface water, and landfill leachate and thermal reactivation of spent sorbents” [Journal of Hazardous Materials Advances (10) 2023, 100311]

Corrigendum to “Sorptive removal of per- and polyfluoroalkyl substances (PFAS) in organic-free water, surface water, and landfill leachate and thermal reactivation of spent sorbents” [Journal of Hazardous Materials Advances (10) 2023, 100311]

Chemical Characteristics and Water Quality Assessment of Groundwater in the Dongjiang-Hanjiang River Basin, China

Groundwater plays an important role in the rapid economic development of the Dongjiang-Hanjiang River Basin. This paper uses the Gibbs model, ionic ratio coefficient analysis, factor analysis, water quality index method and human health risk assessment model to estimate the chemical properties and quality of groundwater in the Dongjiang-Hanjiang Basin. The ion concentration and proportion of SO42- water in the Hanjiang River Basin are higher than those in the Dongjiang River Basin. The groundwater ions come mainly from the dissolution of carbonate rocks, silicate rocks and saline rocks, some of which come from human activities such as industry and mining. Groundwater composition is controlled by rock dissolution, alternating cation adsorption, and human activities. The proportion of rock dissolution is the greatest, but the influence of human activities is obvious. The intensity of human activities such as industry, mining and agriculture is greater in the Hanjiang River Basin than in the Dongjiang River Basin. The overall groundwater quality is poor, and the Dongjiang River Basin is better than the Hanjiang River Basin. The above-standard factors are mainly pH, I−, NO3−, NH4+, As and Pb2+. Nitrate pollution in groundwater is harmful to health and the health risk of children from nitrate is higher than that of adults. The health risk in the Hanjiang River Basin is higher than that in the Dongjiang River Basin. This can serve as a vital reference for similar areas worldwide, offering guidance for groundwater management, pollution prevention and control.

Waste refractory brick material added chitosan/oxidized pullulan complex gel production and removal of heavy metals from waste water

Wastewater is a by-product of numerous industrial processes that have been demonstrated to have adverse effects on human and natural health due to the pollutants it contains. The pollutants in these substances are organic or inorganic molecules and heavy metal ions that significantly harm the environment and human health. A variety of techniques have been devised for the removal of heavy metal ions from wastewater. The adsorption process has attracted significant attention due to its straightforward implementation, cost-effectiveness, and the environmentally friendly production of adsorbent materials using biocompatible substances. In this study, the removal of Cu2+ ions from wastewater was conducted using chitosan pullulan, a biocompatible and biodegradable polymer. In addition to chitosan and pullulan, waste refractory materials from a furnace used in iron and steel production were added to these polymer materials to increase the adsorption capacity. The initial step involved grinding the waste refractory brick material. Subsequently, chitosan was dissolved in acetic acid. After that, the refractory material was suspended in this solution, facilitating the formation of hydrogel beads using a NaOH solution. The obtained hydrogels were coated with pullulan to produce polyelectrolyte gel. Pullulan was oxidized to 6-carboxypullulan by the TEMPO (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl) oxidation method and the negatively charged groups in its structure interacted with the positively charged groups in the chitosan structure to produce a complex gel. The chemical structure, morphological analysis, thermal analysis, and water release analysis of the produced waste refractory brick material added chitosan/oxidized pullulan complex gels were examined. The impact of the 6-carboxypullulan coating on the gels’ properties was elucidated. Furthermore, the adsorption of Cu2⁺ was conducted using solutions containing 100, 500, and 1000 ppm Cu2⁺ ions. It has been observed that the material can clean water with over 98% efficiency, even in solutions that exceed the standards set for wastewater. The material’s efficacy in cleaning solutions with concentrations above the standard for wastewater cleaning is evidence of its high performance. Furthermore, the kinetics and isotherm of the adsorption reaction were examined. The kinetics were determined to be consistent with the Pseudo Second Order (chemical reaction controlled) and aligned with the Langmuir and Freundlich Isotherm (mixed adsorption occurred on homogeneous and heterogeneous surfaces).

Saturation transfer (CEST and MT) MRI for characterization of U-87 MG glioma in the rat.

The focus of this work was to identify the optimal magnetic resonance imaging (MRI) contrast between orthotopic U-87 MG tumours and normal appearing brain with the eventual goal of treatment response monitoring. U-87 MG human glioblastoma cells were injected into the brain of RNU nude rats (n= 9). The rats were imaged at 7T at three timepoints for all animals: 3-5, 7-9, and 11-13 days after implantation. Whole-brain T1-weighted (before and after gadolinium contrast agent injection), diffusion, and fluid-attenuated inversion recovery scans were performed. In addition, single-slice saturation-transfer-weighted chemical exchange saturation transfer (CEST), magnetization transfer (MT), and water saturation shift referencing (WASSR) contrast Z-spectra and T1 and T2 maps were also acquired. The MT and WASSR Z-spectra and T1 map were fitted to a two-pool quantitative MT model to estimate the T2 of the free and macromolecular-bound water molecules, the relative macromolecular pool size (M0, MT), and the magnetization exchange rate from the macromolecular pool to the free pool (RMT). The T1-corrected apparent exchange-dependent relaxation (AREX) metric to isolate the CEST contributions was also calculated. The lesion on M0, MT and AREX maps with a B1 of 2μT best matched the hyperintensity on the post-contrast T1-weighted image. There was also good separation in Z-spectra between the lesion and contralateral cortex in the 2-μT CEST and 3- and 5-μT MT Z-spectra at all time points. A pairwise Wilcoxon signed-rank tests with Holm-Bonferroni adjustment on MRI parameters was performed and the differences between enhancing lesion and contralateral cortex for the MT ratio with 2μT saturation at 3.6ppm frequency offset (corresponding to the amide chemical group) and M0, MT were both strongly significant (p< 0.001) at all time points. This work has identified that differences between enhancing lesion and contralateral cortex are strongest in MTR with B1=2μT at 3.6ppm and relative macromolecular pool size (M0, MT) images over entire period of 3-13 days after cancer cell implantation.

In-vitro and in-vivo assessment of the bactericidal potential of peracetic acid and hydrogen peroxide disinfectants against A. hydrophila infection in Nile tilapia and their effect on water quality indices and fish stress biomarkers

This study aimed to assess the in vitro and in vivo disinfectant potential of peracetic acid (PAA) (1 mg/L) and hydrogen peroxide (H2O2) (20 mg/L) on the physicochemical and microbiological water quality parameters of fish aquaria, the microbial density of Nile tilapia muscular tissue, fish hepatic cortisol levels, and antioxidant biomarkers. In vitro, PAA and H2O2 reduced A. hydrophila colony viability by 5 log units after 30 and 5 min of contact time, respectively. PAA and H2O2 were added to aquaria water twice a week for the three-week experiment. Increased fish escape reflexes were observed only in the PAA group, which returned to normal within 10 min. No mortalities were reported in either the PAA or H2O2 groups. An in vivo experimental challenge with a pathogenic strain of A. hydrophila revealed a 20% reduction in mortality in the PAA group, with no mortalities in the H2O2 group. Cortisol levels and antioxidant markers were measured to assess the impact of PAA and H2O2 on fish health. Cortisol levels in the PAA and H2O2 groups were significantly higher than in the control group after disinfectant exposure, but they progressively returned to normal. A significant reduction in superoxide dismutase (SOD) and catalase (CAT) activity, along with considerably higher glutathione peroxidase (GPx) and malondialdehyde (MDA) enzymatic activity, was observed in the PAA and H2O2 groups compared to the control group. A substantial increase in total antioxidant capacity (TAC) was recorded in the PAA group. Physicochemical analyses revealed reduced pH and increased dissolved oxygen levels in the PAA and H2O2 groups. Microbiological analyses showed a significant reduction in bacterial density in water by 64% and 76% after 30 min of exposure to PAA and H2O2, respectively, with a non-significant increase in microbial count after bacterial challenge. Additionally, aerobic bacterial count, Aeromonas spp., and psychotropic bacterial count in fish muscle showed a significant reduction in the H2O2 group compared to the PAA and control groups before and after infection. The study concludes that regular application of PAA and H2O2 can temporarily reduce bacterial load in aquaria and fish muscle, regulate stress responses, and improve fish health by reducing A. hydrophila-induced infections and improving survival.

Evaluation of physical and chemical isolation methods to extract and purify Campylobacter jejuni extracellular polymeric substances

The pathogenic bacterium Campylobacter jejuni is a major food safety concern as it can form biofilms that increase its survival and infective potential. Biofilms consist of microbial cells and extracellular matrix (ECM), which is made of water and extracellular polymeric substances (EPS), which are critical for structural integrity and pathogenicity. The aim of this study was to optimize a protocol for the isolation of C. jejuni ECM. We employed eight physical and chemical isolation methods to extract and purify ECM, followed by different qualitative and quantitative analyses using gel electrophoresis and spectroscopy. This comprehensive approach enabled the evaluation of ECM composition in terms of polysaccharides, proteins, and extracellular DNA. The isolation methods resulted in different yields and purities of the extracted ECM components. Centrifugation in combination with chemical treatments proved to be most effective, isolating higher concentrations of polysaccharides and proteins. Additionally, extraction with ether solution facilitated the recovery of high-molecular-weight extracellular DNA. Overall, we provide a refined methodology for ECM extraction from C. jejuni. As polysaccharides and proteins participate in biofilm stability and microbial communication, and extracellular DNA participates in genetic exchange and virulence, our study contributes towards a better understanding of the persistence of this pathogen in the food industry.

Profil Pemahaman Representasi Mikroskopik Mahasiswa IPA pada Materi Larutan Elektrolit dan Non-elektrolit

Chemistry as one of the natural sciences has the characteristic of abstract concepts where the concepts in chemistry cannot be perceived by the senses so that special visualization is needed. Therefore, to understanding the abstract concept in chemistry, multiple representations are known, namely macroscopic, microscopic, and symbolic representations. This microscopic representation is used to visualize abstract concepts at the molecular level. However, in chemistry learning, especially at the high school level, it is still very rare to find chemistry learning that involves understanding chemical concepts at the microscopic level. So the aim of this study is to determine the profile of microscopic representation understanding of IPA college students as prospective teachers on the material of electrolyte and non-electrolyte solutions. The descriptive quantitative method with a test approach was used as a method in this study and the sample is 72 Tadris IPA college students of IAIN Ponorogo in the 2023/2024 academic year. The results of the study show that in the category of analysis of differences between strong electrolyte and weak electrolyte solutions, students' understanding of microscopic representation is low, while in the category of analysis the solubility of a substance in water, students' understanding of microscopic representation was classified as moderate.

Incorporating ultrashort-chain compounds into the comprehensive analysis of per- and polyfluorinated substances in potable and non-potable waters by LC-MS/MS

Ultrashort-chain (USC) per- and polyfluoroalkyl substances (PFAS) are small and very polar compounds with carbon chain lengths shorter than C4. Their ubiquitous and high levels of occurrence in environmental aquatic systems are emerging as a significant concern, rivaling the well-established issues associated with long-chain PFAS contamination. Therefore, it is important to analyze both USC and long-chain PFAS together in water samples to comprehensively assess and address the full spectrum of PFAS contamination. The high polarity of USC PFAS poses a challenge for standard chromatographic practices in PFAS analysis, primarily due to insufficient chromatographic retention. In this study, a simple and reliable workflow was developed for the simultaneous analysis of C1 to C14 perfluoroalkyl carboxylic and sulfonic acids, along with other groups of PFAS, in both potable and non-potable waters. The chromatographic separation was conducted using a polar-embedded reversed-phase LC column with an inert coating on the hardware. Three different water matrices (tap water, bottled water, sewage treatment wastewater) were chosen for method evaluation to demonstrate the applicability of the developed workflow for measuring 45 PFAS compounds in diverse water samples. A dilute-and-shoot workflow was evaluated by accuracy and precision analysis at five fortification levels, ranging from 2 to 250 ng/L. Eighteen isotopically labeled PFAS, serving as extracted internal standards, were added to the samples at 100 ng/L to validate the accuracy of the entire workflow. Calibration standards were prepared in reverse osmosis water due to its cleanliness for all analytes. The calibration ranges varied among different analytes, spanning from 1 – 1000 ng/L. All analytes and extracted internal standards exhibited recovery values ranging from 70% to 130% of the nominal concentration across all fortification levels. Satisfactory method precision was demonstrated with %RSD values below 20%. Additional potable and non-potable waters collected from various source waters were tested to further demonstrate that the established workflow is suitable for the accurate quantification of targeted PFAS in a wide range of water matrices.

Mining and urbanization affect river chemical water quality and macroinvertebrate communities in the upper Selenga River basin, Mongolia (revised version).

Mongolia is a country with a quickly growing economy mainly based on the mining of gold, copper, coal, and other minerals. Mining, urbanization, and agriculture impact the water quality in the upper Selenga River basin in northern Mongolia, which is the center of the Mongolian economy. Previous measurements of pollution loads were alarming, but restricted to chemical measurements. Here, for the first time, we combine freshwater biomonitoring and laboratory water quality data across a broad gradient of water quality and land use intensity. We track the effects of different types of pollution on aquatic invertebrates and test their use as bioindicators. We collected water samples, environmental parameters, and macroinvertebrates at 36 sampling sites at the rivers of Tuul, Kharaa, and Orkhon and their tributaries Sugnugur, Boroo, Sharyn Gol, Gatsuurt, and Yeröö. PCA of catchment water quality distinguished three groups of pollutants prevalent at the sites, (1) nutrients, (2) salt ions(Cl-, Na+, Mg2+, So42-, Ca2+) and mining by-products (B, Sr, U, Mo), and (3) (heavy) metals, which often exceeded regulatory standards. We recorded a total of 59 macroinvertebrate taxa belonging to 31 families in seven insect orders plus Amphipoda and Gastropoda. Species diversity declined with higher impact. Five environmental factors structured macroinvertebrate community composition in RDA: elevation of sample location, site total nitrogen, dissolved oxygen, electrical conductivity, and water chemistry. We conclude that macroinvertebrate communities are an appropriate and inexpensive tool for monitoring water quality in Mongolia and suggest government action to establish a long-term monitoring program.

Illegal Substance Analysis and Environmental Risk Assessment in Küçük Menderes River, Important Basin of the Aegean Region.

Water-based studies have come into prominence for illegal substance monitoring. There are limited studies on the detection of these substances in the surface waters as opposed to wastewater. This study aims to evaluate amphetamine, benzoylecgonine, cocaine, codeine, 3,4-methylenedioxy-N-methylamphetamine, morphine, and 11-nor-Δ9- tetrahydrocannabinol-9-carboxylic acid in the Küçük Menderes (KM) River at four different stations during three different periods and assess the environmental risks. Environmental risk assessment of psychoactive substances based on the calculation of Risk Quotients (RQ) were evaluated. RQ values for amphetamine and benzoylecgonine were < 0.01 at all sampling points during all sampling periods, indicating little risk for aquatic life. Cocaine was found as environmentally high risk (RQ > 1) based on its RQ values of 1.22 and 1.37 at KM-01 and KM-02 sampling points. This research is the first report to investigate the presence of psychoactive substances and define the environmental risks of these substances in Türkiye.

The Effect of Szigetvár Medicinal Water on HaCaT Cells Exposed to Dithranol.

(1) Introduction: Topical dithranol is still commonly used today as an effective treatment for psoriasis. Dithranol treatment is often supplemented with balneotherapy, which has been shown to increase effectiveness and reduce side effects. The inorganic salts (sulfhide, selenium, zinc) are usually thought to be responsible for the effect. The antioxidant effect of the waters is thought to be behind the therapeutic effect, for which inorganic substances (sulfides, selenium, zinc) are thought to be responsible. The organic matter content of medicinal waters is also particularly important, as humic acids, which are often found in medicinal waters, have antioxidant effects. (2) Methods: In this short-term experiment, we aimed to test the possible protective effect of Szigetvár medicinal water and its organic matter isolate on HaCaT cells exposed to dithranol. Malondialdehyde levels were measured, and RT-qPCR was used to investigate the gene expression of selected cytokines relevant in the oxidative stress response (IL-6, IL-8, TNF-α, GM-CSF) and the expression of microRNA-21. (3) Results: Szigetvár medicinal water and the organic isolate prevented the increase in malondialdehyde levels caused by dithranol treatment. The cytokine gene expressions elevated by dithranol exposure were reduced by the treatment. (4) Conclusions: Szigetvár medicinal water and organic substances alone may have a protective effect on patients' healthy skin surfaces against dithranol damage. We also demonstrated that the organic compounds are also responsible for the protective effect.

How the Affordances of Different Modeling Tools Impact Kindergartener‐Constructed Models and Modeling Reasoning

ABSTRACTThis study seeks to enrich our understanding of modeling‐based learning (MbL) in kindergarten science education, investigating the influences of different modeling tools on kindergarten child‐constructed models and their modeling reasoning. Therefore, this multi‐case study aimed at providing in‐depth descriptions of how MbL was enacted by 66 kindergarteners while combining the use of three modeling tools: paper‐and‐pencil, three‐dimensional structures, and dramatic play. We studied three different classes of children engaged in MbL who studied and modeled three different physical phenomena (wildflowers' parts and their functions, dissolving substances in water, shadow formation). We varied the modeling tools to investigate the ways these tools contributed to children's MbL. Data sources included the child‐constructed models, their modeling discourse, and mechanistic reasoning. From the videotaped lesson transcripts, we developed detailed accounts of the three MbL cases, and we analysed the discourse using modeling frame analysis and mechanistic reasoning analysis, along with the model component artifact analysis of the child‐constructed models. Findings suggested that the use of different modeling tools impacts child‐constructed models and their corresponding modeling‐based mechanistic reasoning. The findings also suggest that children's representational proficiencies seem to be related to the use of a variety of modeling tools, which enabled children to talk about the possible different ways of developing models and the different affordances of the various modeling tools' representational power. We use this evidence to argue that different modeling tools may afford different modeling possibilities that kindergarten children may draw upon possibly combining with modeling resources they have (e.g., role‐playing, storytelling, drawing).

Quantification of Extractable Total Per- and Polyfluoroalkyl Substances in Water Using Persulfate Preoxidation, Solid Phase Extraction, and Chemical Defluorination with Sodium Biphenyl or Ion-Pair Formation with Methylene Blue

Quantification of Extractable Total Per- and Polyfluoroalkyl Substances in Water Using Persulfate Preoxidation, Solid Phase Extraction, and Chemical Defluorination with Sodium Biphenyl or Ion-Pair Formation with Methylene Blue

The Feasibility of Using Electrostatic Interactions for Immobilizing Ru-bda Catalysts in Covalent Organic Framework: A Proof-of-concept.

Heterogenetization of molecular catalysts effectively resolves the separation issues of homogeneous catalysts and expands their application scenarios. In recent years, more and more studies have been using non-covalent interactions to achieve the heterogenization of molecular catalysts. Herein, electrostatic attraction was used to immobilize molecular catalysts, Ru-bda small molecular catalysts in COF materials, where the charged Ru-bda catalysts were immobilized in the oppositely charged COF with a high [Ru] loading content of ~0.2 mmol [Ru] g-1 COF. The leakage experiment verified that the immobilization of Ru-bda catalysts in COF by electrostatic interactions is stable in 0.1 M HClO4 and less than 5% of molecular Ru-bda catalysts were leached into the solution in 2 hours. The chemical water oxidation experiment was conducted as a model catalysis reaction to verify the feasibility of using electrostatic interactions for immobilizing Ru-bda catalysts in COFs. The prepared Ru(bda)@COFs demonstrate a high catalytic activity of 268 μmol L-1 s-1 O2 for chemical water oxidation, illustrating the electrostatic attractions between COF and small molecules that can be used to immobilize homogeneous catalysts in heterogeneous materials. However, the robustness of COF material itself under catalytic conditions should be considered in practical applications.