{"results":[{"id":"ss_73bcf82127fc87dd8db7dafc3de241f7e81aab2f","title":"The Role of Soil pH in Plant Nutrition and Soil Remediation","authors":[{"name":"D. Neina"}],"abstract":"In the natural environment, soil pH has an enormous influence on soil biogeochemical processes. Soil pH is, therefore, described as the “master soil variable” that influences myriads of soil biological, chemical, and physical properties and processes that affect plant growth and biomass yield. This paper discusses how soil pH affects processes that are interlinked with the biological, geological, and chemical aspects of the soil environment as well as how these processes, through anthropogenic interventions, induce changes in soil pH. Unlike traditional discussions on the various causes of soil pH, particularly soil acidification, this paper focuses on relationships and effects as far as soil biogeochemistry is concerned. Firstly, the effects of soil pH on substance availability, mobility, and soil biological processes are discussed followed by the biogenic regulation of soil pH. It is concluded that soil pH can broadly be applied in two broad areas, i.e., nutrient cycling and plant nutrition and soil remediation (bioremediation and physicochemical remediation).","source":"Semantic Scholar","year":2019,"language":"en","subjects":["Environmental Science"],"doi":"10.1155/2019/5794869","url":"https://www.semanticscholar.org/paper/73bcf82127fc87dd8db7dafc3de241f7e81aab2f","pdf_url":"https://downloads.hindawi.com/journals/aess/2019/5794869.pdf","is_open_access":true,"citations":1090,"published_at":"","score":93},{"id":"ss_f9b2d921d795098e1a9171b233b9ff8d01aacbe4","title":"A Critical Review on Soil Chemical Processes that Control How Soil pH Affects Phosphorus Availability to Plants","authors":[{"name":"C. Penn"},{"name":"J. Camberato"}],"abstract":"Occasionally, the classic understanding of the effect of pH on P uptake from soils is questioned through the claim that maximum P uptake occurs at a pH much lower than 6.5–7. The purpose of this paper was to thoroughly examine that claim and provide a critical review on soil processes that control how soil pH affects P solubility and availability. We discuss how individual P retention mechanisms are affected by pH in isolation and when combined in soils, and how both real and apparent exceptions to the classic view can occasionally occur due to dynamics between mechanisms, experimental techniques (equilibration time, method of soluble P extraction, and pH adjustment), and plant species that thrive under acidic conditions. While real exceptions to the rule of thumb of maximum P availability at near neutral pH can occur, we conclude that the classic textbook recommendation is generally sound.","source":"Semantic Scholar","year":2019,"language":"en","subjects":["Chemistry"],"doi":"10.3390/AGRICULTURE9060120","url":"https://www.semanticscholar.org/paper/f9b2d921d795098e1a9171b233b9ff8d01aacbe4","pdf_url":"https://www.mdpi.com/2077-0472/9/6/120/pdf?version=1559979237","is_open_access":true,"citations":753,"published_at":"","score":85.59},{"id":"ss_4555d241f7f7a5b7b73ed100f7cfb70bc7d58105","title":"Preparation and application of pH-responsive drug delivery systems.","authors":[{"name":"Haitao Ding"},{"name":"Ping Tan"},{"name":"Shiqin Fu"},{"name":"Xiaohe Tian"},{"name":"Hu Zhang"},{"name":"Xuelei Ma"},{"name":"Zhongwei Gu"},{"name":"Kui Luo"}],"abstract":"Microenvironment-responsive drug delivery systems (DDSs) can achieve targeted drug delivery, reduce drug side effects and improve drug efficacies. Among them, pH-responsive DDSs have gained popularity since the pH in the diseased tissues such as cancer, bacterial infection and inflammation differs from a physiological pH of 7.4 and this difference could be harnessed for DDSs to release encapsulated drugs specifically to these diseased tissues. A variety of synthetic approaches have been developed to prepare pH-sensitive DDSs, including introduction of a variety of pH-sensitive chemical bonds or protonated/deprotonated chemical groups. A myriad of nano DDSs have been explored to be pH-responsive, including liposomes, micelles, hydrogels, dendritic macromolecules and organic-inorganic hybrid nanoparticles, and micron level microspheres. The prodrugs from drug-loaded pH-sensitive nano DDSs have been applied in research on anticancer therapy and diagnosis of cancer, inflammation, antibacterial infection, and neurological diseases. We have systematically summarized synthesis strategies of pH-stimulating DDSs, illustrated commonly used and recently developed nanocarriers for these DDSs and covered their potential in different biomedical applications, which may spark new ideas for the development and application of pH-sensitive nano DDSs.","source":"Semantic Scholar","year":2022,"language":"en","subjects":["Medicine"],"doi":"10.1016/j.jconrel.2022.05.056","url":"https://www.semanticscholar.org/paper/4555d241f7f7a5b7b73ed100f7cfb70bc7d58105","is_open_access":true,"citations":448,"published_at":"","score":79.44},{"id":"ss_748b3e49de6a3dee3605a456d97eab02a49deabf","title":"Optical Sensing and Imaging of pH Values: Spectroscopies, Materials, and Applications","authors":[{"name":"Andreas Steinegger"},{"name":"O. Wolfbeis"},{"name":"S. Borisov"}],"abstract":"This is the first comprehensive review on methods and materials for use in optical sensing of pH values and on applications of such sensors. The Review starts with an introduction that contains subsections on the definition of the pH value, a brief look back on optical methods for sensing of pH, on the effects of ionic strength on pH values and pKa values, on the selectivity, sensitivity, precision, dynamic ranges, and temperature dependence of such sensors. Commonly used optical sensing schemes are covered in a next main chapter, with subsections on methods based on absorptiometry, reflectometry, luminescence, refractive index, surface plasmon resonance, photonic crystals, turbidity, mechanical displacement, interferometry, and solvatochromism. This is followed by sections on absorptiometric and luminescent molecular probes for use pH in sensors. Further large sections cover polymeric hosts and supports, and methods for immobilization of indicator dyes. Further and more specific sections summarize the state of the art in materials with dual functionality (indicator and host), nanomaterials, sensors based on upconversion and 2-photon absorption, multiparameter sensors, imaging, and sensors for extreme pH values. A chapter on the many sensing formats has subsections on planar, fiber optic, evanescent wave, refractive index, surface plasmon resonance and holography based sensor designs, and on distributed sensing. Another section summarizes selected applications in areas, such as medicine, biology, oceanography, bioprocess monitoring, corrosion studies, on the use of pH sensors as transducers in biosensors and chemical sensors, and their integration into flow-injection analyzers, microfluidic devices, and lab-on-a-chip systems. An extra section is devoted to current challenges, with subsections on challenges of general nature and those of specific nature. A concluding section gives an outlook on potential future trends and perspectives.","source":"Semantic Scholar","year":2020,"language":"en","subjects":["Chemistry","Medicine"],"doi":"10.1021/acs.chemrev.0c00451","url":"https://www.semanticscholar.org/paper/748b3e49de6a3dee3605a456d97eab02a49deabf","pdf_url":"https://doi.org/10.1021/acs.chemrev.0c00451","is_open_access":true,"citations":475,"published_at":"","score":78.25},{"id":"ss_f042b50222e901dec8190d8d90c7619dfd3986ed","title":"The soil pH and heavy metals revealed their impact on soil microbial community.","authors":[{"name":"Misbah Naz"},{"name":"Z. Dai"},{"name":"Sajid T. Hussain"},{"name":"M. Tariq"},{"name":"Subhan Danish"},{"name":"I. Khan"},{"name":"S. Qi"},{"name":"D. Du"}],"abstract":"Soil microbial community is the main indicator having a crucial role in the remediation of polluted soils. These microbes can alter soil pH, organic matter in soils (SOM), soil physic-chemical properties, and potential soil respiration rate via their enzymatic activities. Similarly, heavy metals also have a crucial role in soil enzymatic activities. For this purpose, a number of methods are studied to evaluate the impact of soil pH (a key factor in the formation of biogeographic microbial patterns in bacteria) on bacterial diversity. The effects of pH on microbial activity are glamorous but still unclear. Whereas, some studies also indicate that soil pH alone is not the single key player in the diversity of soil bacteria. Ecological stability is achieved in a pollution-free environment and pH value. The pH factor has a significant impact on the dynamics of microbes' communities. Here, we try to discuss factors that directly or indirectly affect soil pH and the impact of pH on microbial activity. It is also discussed the environmental factors that contribute to establishing a specific bacterial community structure that must be determined. From this, it can be concluded that the environmental impact on soil pH, reducing soil pH and interaction with this factor, and reducing the effect of soil pH on soil microbial community.","source":"Semantic Scholar","year":2022,"language":"en","subjects":["Medicine"],"doi":"10.1016/j.jenvman.2022.115770","url":"https://www.semanticscholar.org/paper/f042b50222e901dec8190d8d90c7619dfd3986ed","is_open_access":true,"citations":375,"published_at":"","score":77.25},{"id":"ss_f91120836a1f3187459d4280d9d62d15f6e7956b","title":"The effects of pH on nutrient availability depend on both soils and plants","authors":[{"name":"N. Barrow"},{"name":"A. Hartemink"}],"abstract":"The effects of pH on nutrient availability are not solely caused by to the effects on reaction with soils but are an interaction between these effects and the effects on rate of uptake by plants. Some effects are specific to particular ions, but an important aspect is that plant roots and soil particles both have variable charge surfaces. This influences availability, but in opposite directions. Sulfate is an example of this interplay. Its sorption by soil decreases markedly with increasing pH and thus “soil availability” increases. However, plant uptake also decreases with increasing pH thus “plant availability” decreases. For phosphate, the plant effect is stronger than the soil effect and uptake decreases with increasing pH. In contrast, effects of increasing pH on molybdate adsorption are so large that they dominate the overall effect. Sorption of cations, such as zinc or copper, increases with increasing pH but uptake rate also increases. The net effect is a small decrease in availability with increasing pH. Boron is an exception; there are small effects of pH on sorption; and it is the uncharged boric acid molecules that are taken up by plant roots. Their uptake is not affected by charge and uptake is proportional to the concentration of uncharged boric acid molecules. We argue that emphasis on the effects of pH on reactions with soil has led to a distorted picture of the effects of pH on nutrient availability.","source":"Semantic Scholar","year":2023,"language":"en","subjects":null,"doi":"10.1007/s11104-023-05960-5","url":"https://www.semanticscholar.org/paper/f91120836a1f3187459d4280d9d62d15f6e7956b","pdf_url":"https://link.springer.com/content/pdf/10.1007/s11104-023-05960-5.pdf","is_open_access":true,"citations":297,"published_at":"","score":75.91},{"id":"ss_2e5a9ab9ebfa7203251a94ccc0de0aa3e476895a","title":"Soil organic matter priming: The pH effects","authors":[{"name":"Chaoqun Wang"},{"name":"Y. Kuzyakov"}],"abstract":"Priming of soil organic matter (SOM) decomposition by microorganisms is a key phenomenon of global carbon (C) cycling. Soil pH is a main factor defining priming effects (PEs) because it (i) controls microbial community composition and activities, including enzyme activities, (ii) defines SOM stabilization and destabilization mechanisms, and (iii) regulates intensities of many biogeochemical processes. In this critical review, we focus on prerequisites and mechanisms of PE depending on pH and assess the global change consequences for PE. The highest PEs were common in soils with pH between 5.5 and 7.5, whereas low molecular weight organic compounds triggered PE mainly in slightly acidic soils. Positive PEs up to 20 times of SOM decomposition before C input were common at pH around 6.5. Negative PEs were common at soil pH below 4.5 or above 7 reflecting a suboptimal environment for microorganisms and specific SOM stabilization mechanisms at low and high pH. Short‐term soil acidification (in rhizosphere, after fertilizer application) affects PE by: mineral‐SOM complexation, SOM oxidation by iron reduction, enzymatic depolymerization, and pH‐dependent changes in nutrient availability. Biological processes of microbial metabolism shift over the short‐term, whereas long‐term microbial community adaptations to slow acidification are common. The nitrogen fertilization induced soil acidification and land use intensification strongly decrease pH and thus boost the PE. Concluding, soil pH is one of the strongest but up to now disregarded factors of PE, defining SOM decomposition through short‐term metabolic adaptation of microbial groups and long‐term shift of microbial communities.","source":"Semantic Scholar","year":2024,"language":"en","subjects":["Medicine"],"doi":"10.1111/gcb.17349","url":"https://www.semanticscholar.org/paper/2e5a9ab9ebfa7203251a94ccc0de0aa3e476895a","is_open_access":true,"citations":232,"published_at":"","score":74.96000000000001},{"id":"ss_3e36cca127d3a6144e5d8692fe4b772abc12314b","title":"Changes in soil pH and mobility of heavy metals in contaminated soils","authors":[{"name":"Alicja Kicińska"},{"name":"R. Pomykała"},{"name":"M. Izquierdo"}],"abstract":"In the present paper, the authors attempt to explain the importance of pH in soil environment studies and show what mistakes to avoid when measuring pH and interpreting the results obtained. The tests conducted (i.e., extraction in aqua regia, buffer capacity determination, and the impact of acidification on the amount of heavy metals extracted from soils) demonstrated how soil pollution and buffer capacity affect the pace of extracting cadmium (Cd), lead (Pb) and zinc (Zn) cations from heavily polluted and unpolluted soils following gradual acidification. It was shown that soil acidification caused a significant increase in metal mobility in the following order Cd \u003e Zn \u003e Pb and that the highest decrease in pH was observed after adding the first portion of acid. Further addition of acid caused a gradually lower decrease in pH. Soils from the polluted area presented a high buffer capacity. The control samples displayed a distinctly poorer resistance to pH changes in the soil environment. Special focus was placed on cadmium due to its high mobility in soils, even with neutral and slightly alkaline pH. The analyses revealed that in areas heavily polluted by long‐term industrial activity (Igeo \u003e 5 for Zn, Pb and Cd), it is very important to conduct extensive geochemical studies related to the presence and circulation of particularly toxic elements. This is because every environmental factor, especially pH, may significantly affect their mobility, causing metal ions to become more or less active or increasing or decreasing environmental risk related to their presence.","source":"Semantic Scholar","year":2021,"language":"en","subjects":null,"doi":"10.1111/ejss.13203","url":"https://www.semanticscholar.org/paper/3e36cca127d3a6144e5d8692fe4b772abc12314b","is_open_access":true,"citations":317,"published_at":"","score":74.50999999999999},{"id":"ss_51a39e2e59c49b8dbf03d02a00f1594f2806770f","title":"pH‐responsive polymers for drug delivery: Trends and opportunities","authors":[{"name":"J. Singh"},{"name":"P. Nayak"}],"abstract":"Polymer science has applications in biomedical engineering, prosthetics, surgical implants, and prospective pharmaceutical excipients for drug delivery. “Intelligent or Smart Polymers” are created for drug targeting either by derivatization of natural polymers or controlled radical polymerization of electrolytes. Their mode of action is governed by the environmental stimuli viz. temperature, pH, ionic concentration, magnetism, and so on. pH‐responsive polymers, because of their self‐assembling behavior, alter their solubility, conformation, surface activity, and hydrophilicity when exposed to a specific pH. The physiological pH varies from acidic nuclei to alkaline cytoplasm and highly acidic gastric juice to slightly alkaline plasma; thus, various polymers are under study for delivering small molecules, genes, peptides, enzymes, growth factors, and antibodies. The non‐invasive drug delivery routes like oral, ocular, nasal, pulmonary, transdermal, and rectal routes can be explored for targeting recombinant proteins, monoclonal antibodies, and small molecules with particular emphasis on the individual's physiological and pathological state. Further, these polymers can be designed into various architectures like dendrimers, liposomes, micelles, and metallic nanoparticles that can serve as drug reservoirs for sustaining drug release. The challenges in this field are the selection of biocompatible polymers with ease of synthesis and scale‐up, ensuring effective drug‐loading, and stability aspects, producing robust pharmacological data, and timely regulatory approvals. This review exclusively explores the physicochemical characteristics of pH‐responsive polymers, their categorization, various architectural entities, recent studies and patents, and their emerging applications concerning specific diseases.","source":"Semantic Scholar","year":2023,"language":"en","subjects":null,"doi":"10.1002/pol.20230403","url":"https://www.semanticscholar.org/paper/51a39e2e59c49b8dbf03d02a00f1594f2806770f","pdf_url":"https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/pol.20230403","is_open_access":true,"citations":195,"published_at":"","score":72.85},{"id":"ss_5610064871419211125b6621a50f708f69d28edc","title":"pH-Responsive Polymer Nanomaterials for Tumor Therapy","authors":[{"name":"Shunli Chu"},{"name":"Xiaolu Shi"},{"name":"Ye Tian"},{"name":"Fengxiang Gao"}],"abstract":"The complexity of the tumor microenvironment presents significant challenges to cancer therapy, while providing opportunities for targeted drug delivery. Using characteristic signals of the tumor microenvironment, various stimuli-responsive drug delivery systems can be constructed for targeted drug delivery to tumor sites. Among these, the pH is frequently utilized, owing to the pH of the tumor microenvironment being lower than that of blood and healthy tissues. pH-responsive polymer carriers can improve the efficiency of drug delivery in vivo, allow targeted drug delivery, and reduce adverse drug reactions, enabling multifunctional and personalized treatment. pH-responsive polymers have gained increasing interest due to their advantageous properties and potential for applicability in tumor therapy. In this review, recent advances in, and common applications of, pH-responsive polymer nanomaterials for drug delivery in cancer therapy are summarized, with a focus on the different types of pH-responsive polymers. Moreover, the challenges and future applications in this field are prospected.","source":"Semantic Scholar","year":2022,"language":"en","subjects":["Medicine"],"doi":"10.3389/fonc.2022.855019","url":"https://www.semanticscholar.org/paper/5610064871419211125b6621a50f708f69d28edc","pdf_url":"https://www.frontiersin.org/articles/10.3389/fonc.2022.855019/pdf","is_open_access":true,"citations":192,"published_at":"","score":71.75999999999999},{"id":"ss_d8050558e0df54154e34add72854af3443872789","title":"Soil pH - nutrient relationships: the diagram","authors":[{"name":"A. Hartemink"},{"name":"N. Barrow"}],"abstract":"","source":"Semantic Scholar","year":2023,"language":"en","subjects":null,"doi":"10.1007/s11104-022-05861-z","url":"https://www.semanticscholar.org/paper/d8050558e0df54154e34add72854af3443872789","is_open_access":true,"citations":152,"published_at":"","score":71.56},{"id":"ss_89a64d98bd789156bbaeea6bd73bdeaff0eccbd0","title":"pH-Responsive Nanocarriers in Cancer Therapy","authors":[{"name":"Nour Alsawaftah"},{"name":"Nahid S Awad"},{"name":"W. Pitt"},{"name":"G. Husseini"}],"abstract":"A number of promising nano-sized particles (nanoparticles) have been developed to conquer the limitations of conventional chemotherapy. One of the most promising methods is stimuli-responsive nanoparticles because they enable the safe delivery of the drugs while controlling their release at the tumor sites. Different intrinsic and extrinsic stimuli can be used to trigger drug release such as temperature, redox, ultrasound, magnetic field, and pH. The intracellular pH of solid tumors is maintained below the extracellular pH. Thus, pH-sensitive nanoparticles are highly efficient in delivering drugs to tumors compared to conventional nanoparticles. This review provides a survey of the different strategies used to develop pH-sensitive nanoparticles used in cancer therapy.","source":"Semantic Scholar","year":2022,"language":"en","subjects":["Medicine"],"doi":"10.3390/polym14050936","url":"https://www.semanticscholar.org/paper/89a64d98bd789156bbaeea6bd73bdeaff0eccbd0","pdf_url":"https://www.mdpi.com/2073-4360/14/5/936/pdf?version=1646042197","is_open_access":true,"citations":179,"published_at":"","score":71.37},{"id":"crossref_10.1039/d5cp04597e","title":"Molecular dynamics simulations of pH-dependent ciprofloxacin adsorption to Na-montmorillonite","authors":[{"name":"Rogers E. Swai"},{"name":"Michael Holmboe"}],"abstract":"PMF energy profiles from MD simulations enable the prediction of binding affinity and partitioning of ciprofloxacin (CIP) at the montmorillonite (MMT) mineral–water interface, across environmentally relevant pH values.","source":"CrossRef","year":2026,"language":"en","subjects":null,"doi":"10.1039/d5cp04597e","url":"https://doi.org/10.1039/d5cp04597e","is_open_access":true,"published_at":"","score":70},{"id":"ss_77c9371ec122768e177712c818fdcb44885f1a36","title":"Free complement method with Gaussian expanded complements: hierarchical decontraction to mitigate the exponential wall before selection","authors":[{"name":"Cong Wang"}],"abstract":"The previous work (arXiv:2508.04635 [physics.chem-ph]) of the free complement (FC) method with Gaussian expanded complement functions adopts the Slater initial wavefunction. This may introduce an exponential complexity of the variational coefficients associated to the Gaussian complement functions with respect to the number of electrons at a given order before the overlap matrix based selection, for more than one Gaussian function used in the expansion. The present work uses decontractions via the distinct exponents introduced by the $g$ functions to avoid this scenario at low order of the FC method. The exponential number of the variational parameters is postponed to higher orders of the FC expansion.","source":"Semantic Scholar","year":2026,"language":"en","subjects":["Physics"],"url":"https://www.semanticscholar.org/paper/77c9371ec122768e177712c818fdcb44885f1a36","is_open_access":true,"published_at":"","score":70},{"id":"arxiv_2507.19241","title":"Investigating the Role of pH and Counterions in the Intrinsic Fluorescence of Solid-State L-Lysine","authors":[{"name":"Marta Monti"},{"name":"Luca Cimmino"},{"name":"Gonzalo Díaz Mirón"},{"name":"Carlo Diaferia"},{"name":"Debarshi Banerjee"},{"name":"Martina Stella"},{"name":"Luigi Vitagliano"},{"name":"Antonella Accardo"},{"name":"Ali Hassanali"}],"abstract":"There is currently a growing interest in understanding the origins of intrinsic fluorescence as a way to design non-invasive probes for biophysical processes. In this regard, understanding how pH influences fluorescence in non-aromatic biomolecular assemblies is key to controlling their optical properties in realistic cellular conditions. Here, we combine experiments and theory to investigate the pH-dependent emission of solid-state L-Lysine (Lys). Lys aggregates prepared at different pH values using HCl and H$_2$SO$_4$ exhibit protonation- and counterion-dependent morphology and fluorescence, as shown by microscopy and steady-state measurements. We find an enhancement in the fluorescence moving from acidic to basic conditions. To uncover the molecular origin of these trends, we performed non-adiabatic molecular dynamics simulations on three Lys crystal models representing distinct protonation states. Our simulations indicate that enhanced protonation under acidic conditions facilitates non-radiative decay via proton transfer, whereas basic conditions favor radiative decay. Our combined experimental-theoretical work highlights pH and counterion identity as key factors tuning fluorescence in Lys assemblies, offering insights for designing pH responsive optical materials based on non-aromatic amino acids.","source":"arXiv","year":2025,"language":"en","subjects":["physics.chem-ph","physics.bio-ph"],"url":"https://arxiv.org/abs/2507.19241","pdf_url":"https://arxiv.org/pdf/2507.19241","is_open_access":true,"published_at":"2025-07-25T13:06:06Z","score":69},{"id":"arxiv_2502.01028","title":"Electrochemical CO2 capture with pH-independent redox chemistry","authors":[{"name":"Sang Cheol Kim"},{"name":"Marco Gigantino"},{"name":"John Holoubek"},{"name":"Jesse E. Matthews"},{"name":"Junjie Chen"},{"name":"Yaereen Dho"},{"name":"Thomas F. Jaramillo"},{"name":"Yi Cui"},{"name":"Arun Majumdar"},{"name":"Yan-Kai Tzeng"},{"name":"Steven Chu"}],"abstract":"Capture of anthropogenic CO2 is critical for mitigating climate change, and reducing the energy cost is essential for wide-scale deployment. Solubility of inorganic carbon in aqueous solutions depends on the pH, and electrochemical modulation of the pH has been investigated as a means of CO2 capture and release. However, reported methods incur unavoidable energy costs due to thermodynamic penalties. In this study, we introduce a pH-independent redox chemistry that greatly lowers the thermodynamic energy costs by changing the pH without directly changing the [H+]. We show that the redox reaction of TEMPO molecules modulates the pH for capture and release of CO2 in a flow cell with an energy cost as low as 2.6 kJ/mol of CO2 corresponding to 0.027 eV/molecule. A molecular model, supported by MD and DFT simulations, is proposed of how the pH is decreased by 7.6 while largely avoiding the entropic energy cost associated with increasing the [H+]. We believe that this work showcases the potential of pH-independent redox chemistries for practical and cost-effective CO2 capture.","source":"arXiv","year":2025,"language":"en","subjects":["physics.chem-ph"],"url":"https://arxiv.org/abs/2502.01028","pdf_url":"https://arxiv.org/pdf/2502.01028","is_open_access":true,"published_at":"2025-02-03T03:48:04Z","score":69},{"id":"ss_7521fdd5521e8be04054b0e67c288fafe0db05a5","title":"Aerosol pH and its driving factors in Beijing","authors":[{"name":"Jing Ding"},{"name":"P. Zhao"},{"name":"Jie Su"},{"name":"Qun Dong"},{"name":"Xiang Du"},{"name":"Yufen Zhang"}],"abstract":"Abstract. Aerosol acidity plays a key role in secondary aerosol formation. The high-temporal-resolution PM2.5 pH and size-resolved aerosol pH in Beijing were calculated with ISORROPIA II. In 2016–2017, the mean PM2.5 pH (at relative humidity (RH) \u003e 30 %) over four seasons was 4.5±0.7 (winter) \u003e 4.4±1.2 (spring) \u003e 4.3±0.8 (autumn) \u003e 3.8±1.2 (summer), showing moderate acidity. In coarse-mode aerosols, Ca2+ played an important role in aerosol pH. Under heavily polluted conditions, more secondary ions accumulated in the coarse mode, leading to the acidity of the coarse-mode aerosols shifting from neutral to weakly acidic. Sensitivity tests also demonstrated the significant contribution of crustal ions to PM2.5 pH. In the North China Plain (NCP), the common driving factors affecting PM2.5 pH variation in all four seasons were SO42-, TNH3 (total ammonium (gas + aerosol)), and temperature, while unique factors were Ca2+ in spring and RH in summer. The decreasing SO42- and increasing NO3- mass fractions in PM2.5 as well as excessive NH3 in the atmosphere in the NCP in recent years are the reasons why aerosol acidity in China is lower than that in Europe and the United States. The nonlinear relationship between PM2.5 pH and TNH3 indicated that although NH3 in the NCP was abundant, the PM2.5 pH was still acidic because of the thermodynamic equilibrium between NH4+ and NH3. To reduce nitrate by controlling ammonia, the amount of ammonia must be greatly reduced below excessive quantities.","source":"Semantic Scholar","year":2019,"language":"en","subjects":["Chemistry"],"doi":"10.5194/ACP-19-7939-2019","url":"https://www.semanticscholar.org/paper/7521fdd5521e8be04054b0e67c288fafe0db05a5","pdf_url":"https://acp.copernicus.org/articles/19/7939/2019/acp-19-7939-2019.pdf","is_open_access":true,"citations":187,"published_at":"","score":68.61},{"id":"arxiv_2406.00003","title":"pH-sensitive spontaneous decay of functionalised carbon dots in solutions","authors":[{"name":"Denise Dilshener"},{"name":"Drew F. Parsons"},{"name":"Johannes Fiedler"}],"abstract":"Carbon quantum dots have become attractive in various applications, such as drug delivery, biological sensing, photocatalysis, and solar cells. Among these, pH sensing via luminescence lifetime measurements of surface-functionalised carbon dots is one application currently investigated for their long lifetime and autonomous operation. In this manuscript, we explore the theoretical connection between excitation lifetimes and the pH value of the surrounding liquid via the protonation and deprotonation of functional groups. Example calculations applied to m-phenylenediamine, phloroglucinol and tethered disperse blue 1 are shown by applying a separation approach treating the electronic wavefunction of functional groups separately from the internal electronic structure of the (large) carbon dot. The bulk of the carbon dot is treated as an environment characterised by its optical spectrum that shifts the transition rates of the functional group. A simple relationship between pH, pKa and mixed fluorescence lifetime is derived from transition rates of the protonated and deprotonated states. pH sensitivity improves when the difference in transition rates is greatest between protonated and deprotonated species, with the greatest sensitivity found where the pKa is close to the pH region of interest. The introduced model can directly be extended to consider multicomponent liquids and multiple protonation states.","source":"arXiv","year":2024,"language":"en","subjects":["physics.chem-ph"],"url":"https://arxiv.org/abs/2406.00003","pdf_url":"https://arxiv.org/pdf/2406.00003","is_open_access":true,"published_at":"2024-05-08T07:30:04Z","score":68},{"id":"ss_f7126209dc362fefc23ccf1a8a922649ea58263b","title":"Digital twins kinetics of virtual free-radical copolymerization of vinyl monomers with stable radicals. 2. Styrene","authors":[{"name":"E. Sheka"}],"abstract":"The first experience of virtual free-radical copolymerization (FRCP) of methyl methacrylate with stable radicals fullerene C60 and TEMPO in the framework of the digital twins (DTs) concept (arXiv:2309.11616 [physics.chem-ph]) is extended to styrene. The virtualization of the chemical process is based on a conceptual view of this process from the perspective of a chain reaction that covers a set of elementary reactions (ERs). Such an approach is the most suitable for quantum chemical treatment. The calculations, concerning about 50 such ERs as well as associated DTs, were performed using a semi-empirical version of the unrestricted Hartree-Fock approximation. The main energy and spin-density parameters of the DTs ground state are determined. The barrier profiles of the selected DTs were calculated for the activation energy of the studied reactions to be determined. The decisive role of spins in the formation of transition states of these processes was confirmed. The two stable radicals behave quite differently with respect to the standard FRP of styrene. TEMPO effectively captures monomer-radicals of styrene with the acting free radical not depending on which namely radical is in use. Its copolymerizing action manifests itself as a killing of the FRP thus providing the appearance of an induction period (IP) in the total process kinetics. In contrast, the copolymerizing action of fullerene drastically depends on the active free radical. In the case of the alkyl-nitrile one, the fullerene switches to the role of initiator and first provides the styrene polymerization followed with anchoring of the formed polymer chains to the molecule body, after which the standard FRP starts. In the case of benzoyl-peroxide one, fullerene acts an inhibitor thus capturing formed monomer-radicals. The obtained virtual kinetic data are in a full consent with experimental reality.","source":"Semantic Scholar","year":2023,"language":"en","subjects":["Physics"],"url":"https://www.semanticscholar.org/paper/f7126209dc362fefc23ccf1a8a922649ea58263b","is_open_access":true,"citations":4,"published_at":"","score":67.12},{"id":"ss_e2dbf15cf37d888f10dd0614889e5c60a9c20959","title":"Digital twins kinetics of virtual free-radical copolymerization of vinyl monomers with stable radicals. 3. N-isopropyl acrylamide","authors":[{"name":"E. Sheka"}],"abstract":"The first experience of virtual free-radical copolymerization (FRCP) of vinyl monomers with stable radicals in the framework of the digital twins (DTs) concept (arXiv:2309.11616 [physics.chem-ph] and arXiv:2311.02752 [cond-mat.mtrl-sci]) is extended to N-isopropylacrylamide (NIPA). The virtualization of the chemical process is based on the concept of a chain reaction that covers a set of elementary reactions (ERs) and is the most suitable for quantum chemical treatment. The calculations were performed using a semi-empirical version of the unrestricted Hartree-Fock approximation. Once input in the chemical reactor, providing free-radical polymerization of NIPA, the fullerene C60 inhibits capturing the formed monomer-radicals and terminates the polymerization. The obtained virtual kinetic data, providing the appearance of an induction period at the initial stage of the NIPA polymerization, are in a full agreement with experimental reality.","source":"Semantic Scholar","year":2023,"language":"en","subjects":["Physics"],"url":"https://www.semanticscholar.org/paper/e2dbf15cf37d888f10dd0614889e5c60a9c20959","is_open_access":true,"citations":2,"published_at":"","score":67.06}],"total":8624817,"page":1,"page_size":20,"sources":["arXiv","CrossRef","Semantic Scholar"],"query":"physics.chem-ph"}