Ionic Groups Research Articles

IMPROVED SORPTION OF PRASEODYMIUM IONS FROM NITRATE SOLUTIONS BY ACTIVATED ION EXCHANGERS

In this research, we investigated the praseodymium ions sorption by the ion exchangers KU-2-8 (H+form) and AV-17-8 (OH-form) as an interpolymer system called "KU-2-8:AV-17-8" (X:Y) with the molar ratio of ionic groups X:Y (6:0, 5:1, 4:2, 3:3, 2:4, 1:5, and 0:6) in praseodymium nitrate solution. To be clear, two cross-linked polymers having active functional groups that are in the same solution but not in direct contact form an interpolymer system. The purposeof our research to demonstrate how activating ion exchangers as functional polymers by remote contact in an aqueous medium enhances the sorption of a variety of valuable metals and their compounds from industrial waste solutions, including praseodymium. Objects.Ion exchangers that are mutually activated in an aqueous medium undergo conformational and electrochemical changes that lead to a shift in their state from neutral to highly ionized and an increase in their sorption activity toward target metal ions. Results.The experimental findings showed that the sorption activity of the interpolymer system KU-2-8:AV-17-8 (5:1) increased significantly when compared to praseodymium ions (43 %), but the sorption activity of the raw KU-2-8 (6:0) and raw AV-17-8 (0:6) had the same values of 25 % and 5 %, respectively. Conclusion. This research sheds light on a novel and promising approach to improve the efficiency of ion exchangers, opening possibilities for the effective recovery and removal of valuable metals from complex solutions. Additionally, it holds practical implications for sustainable waste management and resource recycling, contributing to the advancement of environmental protection and resource conservation in various industrial sectors. Further investigations and optimization of the interpolymer system could yield substantial benefits for greener and more resource-efficient future sorption technologies.

Constructing cationic flexible covalent organic frameworks through post-functionalization for enhancing the iodine adsorption capacity

With the incresing development of nuclear power plants, the radioactive iodine produced from nuclear waste and nuclear accidents poses increasing threat to the human health and environment. The iodine adsorption behavior of the neutral flexible covalent organic skeleton has been somewhat studied, but to our knowledge, there are no reports of iodine capture by ionized flexible COFs. Herein, we apply a post-functionalization process to construct two cationic flexible COFs (iCOFs-AB-1 and iCOFs-AB-2) for the first time. The iCOFs-AB-1 and iCOFs-AB-2 exhibit I2 uptake capacities of 3.36 and 4.26 g g−1 at 77 °C, which are improved 1.19 and 1.14 times compared to that of neutral flexible COFs. The promotion of ionic groups on iodine adsorption and the iodine valence states adsorbed at diverse sites have identified by experiments. The adsorption mechanism studies show that the segregative bromide and iodide anions in iCOFs-AB-1 and iCOFs-AB-2 can induce molecular iodine to engender polyiodide anions, and the quaternary ammonium salt cations in iCOFs-AB-1 and iCOFs-AB-2 can come into being the Coulomb interaction force with the aforementioned polyiodide anions. This study demonstrates an efficient method to synthesize cationic flexible COFs and further use them as adsorbents for capturing iodine.

Interaction of Polyanionic and Polycationic Brushes with Globular Proteins and Protein-like Nanocolloids.

A large number of experimental studies have demonstrated that globular proteins can be absorbed from the solution by both polycationic and polyanionic brushes when the net charge of protein globules is of the same or of the opposite sign with respect to that of brush-forming polyelectrolyte chains. Here, we overview the results of experimental studies on interactions between globular proteins and polycationic or polyanionic brushes, and present a self-consistent field theoretical model that allows us to account for the asymmetry of interactions of protein-like nanocolloid particles comprising weak (pH-sensitive) cationic and anionic groups with a positively or negatively charged polyelectrolyte brush. The position-dependent insertion free energy and the net charge of the particle are calculated. The theoretical model predicts that if the numbers of cationic and anionic ionizable groups of the protein are approximately equal, then the interaction patterns for both cationic and anionic brushes at equal offset on the "wrong side" from the isoelectric point (IEP), i.e., when the particle and the brush charge are of the same sign, are similar. An essential asymmetry in interactions of particles with polycationic and polyanionic brushes is predicted when fractions of cationic and anionic groups differ significantly. That is, at a pH above IEP, the anionic brush better absorbs negatively charged particles with a larger fraction of ionizable cationic groups and vice versa.

Designed Polyhydroxyproline Helical Peptide with Ultrarobust Antifouling Capability for Electrochemical Sensing in Diverse Complex Biological Fluids.

Developing a generalized strategy for the nonfouling detection of biomarkers in diverse biological fluids presents a significant challenge. Herein, a polyhydroxyproline helical peptide (PHHP) was designed and adopted to fabricate electrochemical microsensors capable of detecting targets in various biological media. The PHHP possessed unique properties such as strong hydrophilicity, rigid structure, and lack of ionizable side-chain groups. Compared with common zwitterionic peptides (ZIPs), the PHHP exhibited similar antifouling capability but exceptional stability, allowing its antifouling performance to be unaffected by environmental alteration. The PHHP can prevent biofouling even in fluctuating pH conditions, high ionic strength environments, and the presence of high-valence ions and resist the protease hydrolysis. The PHHP-modified carbon fiber microelectrode was further immobilized with an aptamer to construct an antifouling microsensor for cortisol detection across diverse biofluids, and the microsensor exhibited acceptable accuracy and higher sensitivity than the ELISA method. In addition, different biological samples of mice were collected in situ using a microsensing device, and cortisol levels were analyzed in each specifically tailored region. This nonfouling sensing strategy based on PHHP allows a comprehensive assessment of biomarkers in both spatial and temporal dimensions in diverse biological environments, holding promising potential for early disease diagnosis and real-time health monitoring.

Raman spectroscopy and quantum chemical calculation on SmCl3-KCl-LiCl molten salt system

The study on the ionic structure of SmCl3-KCl-LiCl molten systems is of guiding significance for the practical production of metal samarium and samarium alloys via Molten salt electrolysis (MSE) using this system as electrolyte. Based on density functional theory (DFT), the possible ionic groups in SmCl3-KCl-LiCl molten system were simulated by Gaussian and GaussView program and their theoretical Raman spectra were calculated. The calculated spectra were then compared with the experimental Raman spectra of molten 0.1–2 mol% SmCl3-(41 mol% KCl-59 mol% LiCl) to identify the ionic groups which might have existed. It is thought that SmCl4-, SmCl63-, Sm2Cl82- and Sm2Cl7- exist in the molten system. When the temperature is unchanged, the “lifetime” of SmCl63- is reduced while those of SmCl4-, Sm2Cl82- and Sm2Cl7- is increased with the increase of SmCl3 content. Within the temperature range of 773–809 K, when the content of SmCl3 remains unchanged, the “lifetime” of these complex ions decreases with the increase of temperature. Besides, the relative content of SmCl63- decreases with the increase of temperature. The wave function analysis of the four kinds of Sm-Cl ionic groups was also carried out using Multiwfn program. The net atomic charge of each ionic group, the direction of electron migration during the formation of the ionic groups, as well as the most prone to electrophilic and nuclear reactions of each ionic group, and the order of bond breaking during chemical reactions for the four groups were obtained.

Bead-Spring Simulation of Ionomer Melts-Studying the Effects of Chain-Length and Associating Group Fraction on Equilibrium Structure and Extensional Flow Behavior.

Ionomers are associative polymers with diverse applications ranging from selective membranes and high-performance adhesives to abrasion- and chemical-resistant coatings, insulation layers, vacuum packaging, and foamed sheets. Within equilibrium melt, the ionic or associating groups are known to form thermally reversible, associative clusters whose presence can significantly affect the system's mechanical, viscoelastic, and transport properties. It is, thus, of great interest to understand how to control such clusters' size distribution, shape, and stability through the designed choice of polymer architecture and the ionic groups' fraction, arrangement, and interaction strength. In this work, we represent linear associating polymers using a Kremer-Grest type bead-spring model and perform large-scale MD simulations to explore the effect of polymer chain-length (l) and fraction (fs) of randomly placed associating groups on the size distribution and stability of formed clusters. We consider different chain-lengths (below and above entanglement), varying fractions of associating groups (represented by 'sticky' beads) between 5 and 20%, and a fixed sticky-sticky nonbond interaction strength of four times that between regular non-associating beads. For all melts containing associating groups the equilibrium structure factor S(q) displays a signature ionomer peak at low wave vector q whose intensity increases with increasing fs and l. The average cluster size Nc increases with fs. However, the effect of chain-length on Nc appears to be pronounced only at higher values of fs. Under extensional flows, the computed stress (and viscosity) is higher at higher fs and l regardless of strain rate. Beyond a critical strain rate, we observe fragmentation of the associative clusters, which has interesting effects on the stress/viscous response.

Preparation and properties of novel liquid crystal ionomers bearing benzoxazole-based mesogenic side-chains and their membranes

A new heterocyclic mesogenic compound, 6-[4-(5-chloro-2-benzoxazolyl)phenoxy]-hexanethiol (CBPHT), is designed and synthesized, which shows an enantiotropic SmC mesophase with the liquid crystal phase ranges of 5.67 °C and 22.99 °C on heating and cooling, respectively. The CBPHT-based side-chain liquid crystal polymers (LCP-x) are obtained via a nucleophilic substitution between CBPHT and polyepichlorohydrin, and also shows an enantiotropic SmC mesophase with narrow temperature range. Furthermore, novel side-chain liquid crystal ionomers (LCI-x) with enantiotropic SmC mesophase are prepared via quaternization of N-methylimidazole with LCP-x, where polyepichlorohydrin, CBPHT and methylimidazolium chloride act as polymer main-chain, mesogenic side-chain, and ionic group, respectively. In addition, LCI-x membranes can be fabricated via a solution casting method, and exhibit high thermal stability, good mechanical properties and high ion conductivity. For example, LCI-0.20 with a low ion exchange capacity of 0.12 mequiv. g−1 has a large elongation at break (385 %) and a high chloride ion conductivity (20.68 mS cm−1), indicating a high potential for application as polymer electrolyte membrane.

Conjugated Polyelectrolyte Thin Films for Pseudocapacitive Applications.

A subclass of organic semiconductors known as conjugated polyelectrolytes (CPEs) is characterized by a conjugated backbone with ionic pendant groups. The water solubility of CPEs typically hinders applications of thin films in aqueous media. Herein, it is reported that films of an anionic CPE, namely CPE-K, drop cast from water produces single-component solid-state pseudocapacitive electrodes that are insoluble in aqueous electrolyte. That X-ray diffraction experiments reveal a more structurally ordered film, relative to the as-obtained powder from chemical synthesis, and dynamic light scattering measurements show an increase in aggregate particle size with increasing [KCl] indicate that CPE-K films are insoluble because of tight interchain contacts and electrostatic screening by the electrolyte. CPE-K film electrodes can maintain 85% of their original capacitance (84 F g-1 ) at 500 A g-1 and exhibit excellent cycling stability, where a capacitance retention of 93% after 100000 cycles at a current density of 35 A g-1 . These findings demonstrate that it is possible to use initially water soluble ionic-organic materials in aqueous electrolytes, by increasing the electrolyte concentration. This strategy can be applied to the application of conjugated polyelectrolytes in batteries, organic electrochemical transistors, and electrochemical sensors, where fast electron and ion transport are required.

Co-activation of NMDAR and mGluRs controls protein nanoparticle-induced osmotic pressure in neurotoxic edema

BackgroundGlutamate stimuli and hyperactivation of its receptor are predominant determinants of ischemia-induced cytotoxic cerebral edema, which is closely associated with protein nanoparticle (PN)-induced increases in osmotic pressure. Herein, we investigated the electrochemical and mechanical mechanisms underlying the neuron swelling induced by PNs via the co-activation of N-methyl-D-aspartate receptor subunit (NMDAR) and excitatory metabotropic glutamate receptors (mGluRs). ResultsWe observed that co-activation of ionic glutamate receptor NMDAR and Group I metabotropic mGluRs promoted alteration of PN-induced membrane potential and increased intracellular osmosis, which was closely associated with calcium and voltage-dependent ion channels. In addition, activation of NMDAR-induced calmodulin (CaM) and mGluR downstream diacylglycerol (DAG)/protein kinase C α (PKCα) were observed to play crucial roles in cytotoxic hyperosmosis. The crosstalk between CaM and PKCα could upregulate the sensitivity and sustained opening of sulfonylurea receptor 1 (SUR1)-transient receptor potential cation channel subfamily M member 4 (TRPM4) and transmembrane protein 16 A (TMEM16A) channels, respectively, maintaining the massive Na+/Cl- influx, and the resultant neuron hyperosmosis and swelling. Intracellular PNs and Na+/Cl- influx were found to be as potential targets for cerebral edema treatment, using the neurocyte osmosis system and a cerebral ischemic rat model. ConclusionsThis study highlights PNs as a key factor in “electrochemistry-tension” signal transduction controlling Na+/Cl- ion channels and increased osmotic pressure in ischemia-induced cytotoxic edema. Moreover, enhanced sensitivity in both Na+ and Cl- ion channels also has a crucial role in cerebral edema.

Colloidal Nafion Particles: Are Cylinders Ubiquitous?

Colloidal Nafion morphology plays a critical role in determining the performance of fuel cells and electrolyzers. While small-angle neutron scattering (SANS) studies previously described Nafion in liquid media as dispersed cylinders, the analysis remains nonunique with multiple possible morphological descriptions of the data. Here, using SANS and all-atomistic molecular dynamics, we confirm that Nafion morphology in liquid media differs substantially depending on dispersing agent and dispersion method. H+ Nafion dispersed in N-methyl pyrrolidone forms swollen cluster particles with physically cross-linked ionic groups. Scattering profiles from dispersed Nafion membrane have a large structure factor feature not observed for redispersed Nafion D-521. H+ Nafion dispersed in water has a highly elongated cylindrical morphology (radius = 10 ± 1.5 Å, height = 358 ± 4.7 Å) with fully dissociated and solvated sulfonic acid groups on the particle wall. These results highlight an important discrepancy between the methods of preparing Nafion dispersions and the use of simplified analysis techniques to describe Nafion morphology.

Ionenes as Potential Phase Change Materials with Self-Healing Behavior.

Ionenes are poly(ionic liquids) (PILs) comprising a polymer backbone with ionic groups along the structure. Ionenes as solid-solid phase change materials are a recent research field, and some studies have demonstrated their potential in thermal dissipation into electronic devices. Eight ionenes obtained through Menshutkin reactions were synthesized and characterized. The analysis of the thermal tests allowed understanding of how the thermal properties of the polymers depend on the aliphatic nature of the dihalogenated monomer and the carbon chain length. The TGA studies concluded that the ionenes were thermally stable with T10% above 420 °C. The DSC tests showed that the prepared ionenes presented solid-solid transitions, and no melting temperature was appreciated, which rules out the possibility of solid-liquid transitions. All ionenes were soluble in common polar aprotic solvents. The hydrophilicity of the synthesized ionenes was studied by the contact angle method, and their total surface energy was calculated. Self-healing behavior was preliminarily explored using a selected sample. Our studies show that the prepared ionenes exhibit properties that make them potential candidates for applications as solid-solid phase change materials.

Towards sturdy and sensable pressure-sensitive adhesive through hierarchical supramolecular interaction

Endowing a robust pressure-sensitive adhesive (PSA) with sensable properties is of great significance for in-situ stress detection and information encryption in the fields of electronics, energy storage, flexible sensing, etc. However, it remains great challenge due to the difficulty in balancing interfacial wetting and cohesive strength. Herein, a microphase-separated strategy is proposed to construct an ionogel with a lower modulus of 1.96MPa, a strength of 728kPa as well as a remarkable toughness of 2258.9kJ/m3, which can be used as a sturdy PSA bonded to various substrates (metals, polar plastics, non-polar plastics) under gentle pressure. The comparable modulus and cohesive strength give it an excellent adhesion strength of 1340kPa, which far exceeds most of reported high-performance PSAs. Furthermore, due to the orientation of a large number of ionic groups, the adhesion strength increases by 31.3% once a voltage of 20V is applied. Finally, the sensitive force-resistance response of such PSA that can be used for encrypted messaging was demonstrated.

Expanding the Scope of an Amphoteric Condensed Tannin, Tanfloc, for Antibacterial Coatings.

Bacterial infections are a common mode of failure for medical implants. This study aims to develop antibacterial polyelectrolyte multilayer (PEM) coatings that contain a plant-derived condensed tannin polymer (Tanfloc, TAN) with inherent antimicrobial activity. Tanfloc is amphoteric, and herein we show that it can be used as either a polyanion or a polycation in PEMs, thereby expanding the possibility of its use in PEM coatings. PEMs are ordinarily formed using a polycation and a polyanion, in which the functional (ionic) groups of the two polymers are complexed to each other. However, using the amphoteric polymer Tanfloc with weakly basic amine and weakly acidic catechol and pyrogallol groups enables PEM formation using only one or the other of its functional groups, leaving the other functional group available to impart antibacterial activity. This work demonstrates Tanfloc-containing PEMs using multiple counter-polyelectrolytes including three polyanionic glycosaminoglycans of varying charge density, and the polycations N,N,N-trimethyl chitosan and polyethyleneimine. The layer-by-layer (LbL) assembly of PEMs was monitored using in situ Fourier-transform surface plasmon resonance (FT-SPR), confirming a stable LbL assembly. X-ray photoelectron spectroscopy (XPS) was used to evaluate surface chemistry, and atomic force microscopy (AFM) was used to determine the surface roughness. The LDH release levels from cells cultured on the Tanfloc-containing PEMs were not statistically different from those on the negative control (p > 0.05), confirming their non-cytotoxicity, while exhibiting remarkable antiadhesive and bactericidal properties against Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus), respectively. The antibacterial effects were attributed to electrostatic interactions and Tanfloc's polyphenolic nature. This work underscores the potential of Tanfloc as a versatile biomaterial for combating infections on surfaces.

New Perspective on the Interaction Behavior Between Riboflavin and β Lactoglobulin-β Casein Complex by Biophysical Techniques.

Riboflavin (RF) is a vitamin that only exists in plants and microorganisms and must be procured externally by humans. On the other hand, there are two major allergic factors in cow's milk, including β-lactoglobulin (βLG) and β-casein (βCN), while their allergic properties can be eliminated by binding to micronutrients. In this regard, we examined the binding process of RF to βLG and βCN in the binary and ternary systems by different spectroscopies such as zeta potential, electric conductivity, and molecular modeling. According to the result of the fluorescence spectrum regarding the interaction of RF with βLG and βCN in binary and ternary systems, an increase in RF concentration declined the fluorescence intensity of three systems and also caused the quenching of proteins. Static quenching plays a pivotal role in the formation of stable interactions. The obtained thermodynamic parameters by Van't Hoff equation ascertained the predominance of hydrogen bonds and van der Waals interaction in all the systems. Considering how the negative value of ΔH0 resulted in the negative value of ΔG0, the systems were assumed to be enthalpy driven. The outcomes of circular dichroism (CD) disclosed that the attachment of RF to the targets of systems increased their a-helix content, which particularly included the binding of RF to βLG that led to the conversion of β-sheet to α-helix content. As indicated by the results of zeta potential, the low concentration of RF contained the dominance of hydrophobic forces in the interactions, whereas the enlargement of this concentration prevailed electrostatic forces. Moreover, conductometry measurements showed an extension in the rate of ionizable groups due to the addition of RF to the systems, which may increase the probability of an interaction between RF, βCN, and βLG in binary and ternary systems. In consistency with the outcomes of molecular dynamics simulation, the data of molecular docking approved the capability of RF in forming strong and stable interactions with βCN and βLG.

Enhanced topical paromomycin delivery for cutaneous leishmaniasis treatment: Passive and iontophoretic approaches

Conventional treatments for cutaneous leishmaniasis, a neglected vector-borne infectious disease, can frequently lead to serious adverse effects. Paromomycin (PAR), an aminoglycoside antibiotic, has been suggested for the topical treatment of disease-related lesions, but even when formulated in high drug-loading dosage forms, presents controversial efficacy. The presence of five ionizable amino groups hinder its passive cutaneous penetration but make PAR an excellent candidate for iontophoretic delivery. The objective of this study was to verify the feasibility of using iontophoresis for cutaneous PAR delivery and to propose a topical passive drug delivery system that could be applied between iontophoretic treatments. For this, in vitro iontophoretic experiments evaluated different application durations (10, 30, and 360 min), current densities (0.1, 0.25, and 0.5 mA/cm2), PAR concentrations (0.5 and 1.0 %), and skin models (intact and impaired porcine skin). In addition, 1 % PAR hydrogel had its penetration profile compared to 15 % PAR ointment in passive transport. Results showed iontophoresis could deliver suitable PAR amounts to dermal layers, even in short times and with impaired skin. Biodistribution assays showed both iontophoretic transport and the proposed hydrogel delivered higher PAR amounts to deeper skin layers than conventional ointment, even though applying 15 times less drug. To our knowledge, this is the first report of PAR drug delivery enhancement by iontophoresis. In summary, the association of iontophoresis with a topical application of PAR gel seems appropriate for improving cutaneous leishmaniasis treatment.

Intrinsic Solubility of Ionizable Compounds from pKa Shift.

Aqueous solubility of pharmaceutical substances plays an important role in small molecule drug discovery and development, with ionizable groups often employed to enhance solubility. Drug candidate compounds often contain ionizable groups to increase their solubility. Recognizing that the electrostatically charged form of the compound is much more soluble than the uncharged form, this work proposes a model to explore the relationship between the pKa shift of the ionizable group and dissolution equilibria. The model considers three forms of a compound: dissolved-charged, dissolved-uncharged, and aggregated-uncharged. It analyzes two linked equilibria: the protonation of the ionizable group and the dissolution-aggregation of the uncharged form, with the observed pKa shift depending on the total concentration of the compound. The active concentration of the aggregates determines this shift. The model was explored through the determination of the pKa shift and intrinsic solubility of specific compounds, such as ICPD47, a high-affinity inhibitor of the Hsp90 chaperone protein and anticancer target, as well as benzoic acid and benzydamine. The model holds the potential for a more nuanced understanding of intrinsic solubility and may lead to advancements in drug discovery and development.

Molecular level investigation of interactions between pharmaceuticals and β-cyclodextrin (β-CD) functionalized adsorption sites for removal of pharmaceutical contaminants from water

This study describes a novel application of the use of molecular modeling tools for investigating the adsorption of organic micropollutants (OMPs) from water by nanocomposites. The partitioning of pharmaceuticals onto β-Cyclodextrin (β-CD) functionalized adsorbents was investigated at the molecular level to explore the atomistic interactions of pharmaceutical contaminants in water systems with β-CD and to provide insight into possible approaches for removal of pharmaceuticals from water. Molecular electrostatic surface potential mapping of β-CD derivatives was employed to examine the impact of substitution degree of β-CD and type of grafting agent on host-guest complexation. The stability of the complexes of selected pharmaceuticals and β-CD derivatives were assessed via molecular dynamics simulations to evaluate competitive adsorption between organic micropollutants (OMPs) and between OMPs and fulvic acid, a representative natural organic material (NOM) component found in water systems. Molecular electrostatic surface potential maps showed that grafting agents with aromatic and amine functional groups were found to provide attractive interactions for negatively charged OMPs. In addition, optimization of substitution degree of β-CD is necessary to enhance adsorption of target OMPs. Furthermore, it was found that aromatic ring bearing grafting agents can provide additional electrostatic attractions by π-π interactions with the aromatic ring of the OMPs. The impact of common water quality characteristics on adsorption was assessed and it was revealed that the effect of pH and calcium on adsorption depends on the ionizable functional groups present on the grafting agent. Molecular dynamics simulations showed that adsorption of target OMPs does not solely depend on hydrophobicity but is affected by electrostatic interactions. The simulations revealed that fulvic acid which is commonly present in environmental waters can be a competitor with ibuprofen for the β-CD cavity. Ultimately, this study showed that molecular level simulation can be effectively employed to investigate adsorption of OMPs by β-CD functionalized adsorbents and could be employed to enhance their design and subsequent environmental applications.

Chemical and Spectroscopic Characteristics of Humic Acids Under No-Tillage and Forest Systems

ABSTRACT This study aims to evaluate the no-tillage system (NT) with different implantation times and vegetation cover on changes in the chemical and structural compositions of soil humified organic matter. Five areas with different NT management histories were studied; for 6 (NT6), 14 (NT14), 22 (NT22) years with succession of soybean/corn crops; for 12 years and 4 more years with corn and Brachiaria (NT+B), pasture for 39 years and native forest. Soil samples were collected at the depths of 0.0–0.05 and 0.05–0.10 m. The changes in the quality of humic acid (HA) were evaluated by several chemical techniques (total organic carbon (TOC), fulvic acid fraction (FA), humic acid fraction (HA) and humin fraction (HU), ionizable functional groups, elemental composition) and spectroscopic techniques (UV–Vis absorption, fluorescence, and Fourier transform mid-infrared photoacoustic spectroscopy, called FTIR-PAS). On the surface, the TOC, carbon of the HA and HU fractions, total acidity, phenolic acidity, Carbon, Nitrogen, Sulfur, Hydrogen and Hydrogen/Carbon ratio were higher in the areas of forest, pasture and NT22. On the subsurface, the responses are the same as on the surface. However, the NT22 system presents higher FA, HA, carboxylic acidity and humification degree (HD). UV–Vis absorption spectroscopy, fluorescence spectroscopy and FTIR-PAS can discriminate soils under different managements and under natural conditions. Agronomic practices have strongly affected the soil organic matter, in which the NT promotes the formation of HA with characteristics closer to those of the forest, as the implantation time increases, such as 22-year-old NT and pasture. This indicates that care must be taken in managing the no-till system to maximize its potential to promote stabilization of organic matter, thereby contributing to carbon sequestration.

Fabrication and evaluation of novel amphiphilic star block copolymers for increasing free water content in lignite to make coal water slurries

In order to reduce the apparent viscosity of lignite coal water slurries (CWSs) and improve its static stability, a series of three-arm amphiphilic block copolymers have been prepared through RAFT polymerization by using poly(ethylene glycol) methyl ether acrylate (PEGMA) and sodium 4-vinylbenzenesulfonate (SSNa) as hydrophilic monomers and styrene (St) as hydrophobic monomer. The chemical structure of the copolymers has been investigated, and the impact of relative molecular weight, hydrophilic/hydrophobic ratio, and ionic group content on the pulping performance of three-arm amphiphilic block copolymers has been examined. The lignite coal water slurries (CWSs) prepared from the block copolymer tri-P(St50-s-SSNa50)10K-b-PPEGMA10K exhibit a remarkably low apparent viscosity of 395 mPa·s and excellent static stability when the coal content is at 55 wt% and dispersant content is at 0.5 wt%. Moreover, these CWSs can achieve a maximum pulping concentration of up to 59 wt%. Additionally, the thermogravimetric test reveals insights into the water occurrence in CWSs, indicating that higher levels of free water content correspond to lower apparent viscosities. Suitable hydrophobicity facilitates the removal of internal water from lignite by dispersants, disrupting its flocculation structure and promoting CWSs formation. Meanwhile, the presence of ionic groups enhances the static stability of the resulting CWSs. Furthermore, the adsorption behavior of the three-arm amphiphilic block copolymer dispersant in lignite has been analyzed through XPS testing to elucidate its dispersion mechanism. The use of three-arm amphiphilic block copolymers in preparing lignite CWSs results in lower apparent viscosity and improved static stability, attributed to the amphiphilic and steric hindrance effects of dispersants. This not only expands the application range of lignite CWSs but also highlights the significant potential of this type of dispersant.

Water-soluble phthalocyanine photosensitizers for photodynamic therapy.

Photodynamic therapy (PDT) is based on a photochemical reaction that is started when a photosensitizing process is activated by the light and results in the death of tumor cells. Solubility is crucial in PDT applications to investigate the physical and chemical characteristics of phthalocyanines, but, unfortunately, most phthalocyanines show limited solubility especially in water. To increase the solubility of phthalocyanines in polar solvents and water, ionic groups such as -SO3-, -NR3+, -COO-, and nonionic groups such as polyoxy chains are frequently added to the peripheral or nonperipheral positions of the phthalocyanine framework. Since water-solubility and NIR-absorbing properties are essential for efficient PDT activation, studies have been focused on the synthesis of these types of phthalocyanine derivatives. This review focuses on the photophysical, photochemical, and some in vitro or in vivo studies of the recently published ionic and nonionic phthalocyanine-mediated photosensitizers carried out in the last five years. This review will have positive contributions to future studies on phthalocyanine chemistry and their PDT applications as well as photochemistry.