Solution Research Articles

Removal of Hexavalent Chromium (Cr6+) from Aqueous Solutions by Chitosan-halloysite Nanotubes Composite Hydrogel Beads

Background: In recent years, low-cost biomaterials have been used for sustainable applications to reduce the impact of wastewater treatment. The preparation of bio-based materials with a strong affinity for chromate plays a crucial role in the adsorption process. Methods: In this study, chitosan-halloysite nanotubes composite hydrogel beads (Ch-HNTs) were prepared for the removal of hexavalent chromium (Cr6+) from aqueous solutions. Ch-HNTs hydrogel beads were generated by incorporating HNTs into chitosan using a glutaraldehyde solution to achieve efficient crosslinking. The structure of the Ch-HNTs was characterized by SEM and FTIR analysis. These novel adsorbents were then tested for the adsorption of Cr6+ in serial batch experiments. For this purpose, the effect of pH, contact time, temperature, concentration of adsorbate, and adsorbent concentration on the extent of adsorption were investigated. Results: It is proposed that Ch-HNTs can be potential adsorbents for Cr6+ removal from dilute solutions. Nonetheless, further studies on adsorbing and removing various heavy metals using these novel beads in column systems can be planned. Conclusion: It is proposed that Ch-HNTs can be potential adsorbents for Cr6+ removal from dilute solutions. Nonetheless, further studies on adsorbing and removing various heavy metals using these novel beads in column systems can be planned.

Improved konjac glucomannan/curdlan-based emulsion coating by mung bean protein addition for cherry tomato preservation.

Biopolymer-based emulsion systems have been used for food preservation. In this study, mung bean protein (MBP) was added to konjac glucomannan (KGM)/curdlan-based camellia oil emulsion (KC-CO) to develop KCM-CO emulsion system. KCM-CO emulsions showed good compatibility and stability during storage. The confocal laser scanning microscopy, atomic force microscope, and infrared spectroscopy revealed that camellia oil was successfully emulsified by MBP, and the resulting droplets were evenly distributed in the polysaccharide network formed by KGM and curdlan micelles based on hydrogen bonds. The emulsions behaved as an elastic solid, and the KCM-CO emulsion films exhibited a compact microstructure, and the emulsification of MBP enhanced the compatibility, as K54C40M6-CO had the smoothest surface. The addition of MBP significantly improved the elongation at break (EAB), water contact angle (WCA), dissolution, and gas permeability of the emulsion films. K54C40M6-CO showed the largest EAB (37.6%), strong hydrophobicity (WCA=97.8°), and low water vapor and oxygen permeability. In the preservation experiments, K54C40M6-CO coating significantly delayed the weight loss (by 41.2%) and firmness decline (by 54.5%), and maintained the appearance, total solids, total acids, and ascorbic acid content of cherry tomatoes, and inhibited the respiratory intensity by 44.2%. This coating showed great potential for fruit and vegetable preservation.

Modelling the chronopotentiometric response of constant current hydrogen evolution from dilute solutions of strong acids

Modelling the chronopotentiometric response of constant current hydrogen evolution from dilute solutions of strong acids

Ph3AsO as a Strong Hydrogen-Bond Acceptor in Cocrystals with Hydrogen Peroxide and gem-Dihydroperoxides.

Hydrogen-bonded cocrystals have attracted considerable attention as they allow fine-tuning of properties through the choice of hydrogen-bond donors and acceptors. In this study, triphenylarsine oxide (Ph3AsO) is introduced as a strong hydrogen-bond acceptor molecule. Due to its higher Lewis basicity compared to triphenylphosphine oxide (Ph3PO), it acts as a strong hydrogen-bond acceptor, which is demonstrated in six new cocrystals with H2O2 and gem-di(hydroperoxy)cycloalkanes. All cocrystals formed large, high-quality single crystals, which were analyzed by X-ray diffraction and IR spectroscopy. The cocrystal of Ph3AsO with H2O2 shows prolonged stability without loss of oxidative power. In addition, the newly formed interactions were also present in solution and were detected by NMR spectroscopy. The higher electron-donating ability of Ph3AsO compared to Ph3PO was confirmed by competition experiments. Ph3AsO exclusively binds H2O2, even in dilute aqueous solutions and in the presence of Ph3PO. This study expands the range of hydrogen-bond acceptors and demonstrates that Ph3AsO is a useful cocrystallizing tool in crystal engineering and a sensitive marker for hydrogen peroxide.

Emission Tuning of Nonconventional Luminescent Materials via Cluster Engineering.

Nonconventional Luminescent Materials (NLMs) with distinctive optical properties are garnering significant attention. A key challenge in their practical application lies in precisely controlling their emission behavior, particularly achieving excitation wavelength-independent emission, which is paramount for accurate chemical sensing. In this study, NLMs (Y1, Y2, Y3, and Y4) are synthesized via a click reaction, and it is found that excitation wavelength-dependent emission correlates with molecular cluster formation. Rigid NLMs (Y1, Y2) exhibit excitation-independent emission in dilute solutions with nanoscale clusters but become excitation-dependent at higher concentrations due to larger cluster formation. Flexible NLMs (Y3 and Y4) always show excitation-dependent emission, indicating a tendency for larger cluster formation. While these NLMs exhibit high photoluminescence quantum yields (PLQYs) in dilute solutions (0.1 mgmL-1) up to 38.0%, they suffer from significant aggregation-caused quenching (ACQ) in the solid state (as low as 0.5%). These findings provide insights into NLM luminescence mechanisms and offer a new approach for tuning their optical properties. With excellent optical properties, facile synthesis, and biocompatibility, these NLMs hold promise for bioimaging and other applications.

Acid-Vapor-Responsive Supramolecular Gels of Hydrogen-Bonding D–A type Fluorenones

Abstract In this study, we investigated the gelation properties and stimulus-responsive behavior of donor–acceptor–donor-type (D–A–D-type) fluorenone derivatives bearing urethane units. The fluorenone derivatives exhibited characteristic photophysical properties that originate from π–π* and intramolecular charge-transfer (ICT) transitions, and dilute solutions exhibited fluorescence solvatofluorochromic behavior. In addition, the D–A–D-type fluorenone derivatives formed supramolecular gels in appropriate organic solvents; these gels also exhibited acid-vapor-responsive functional variations.

Beta‐Lactoglobulin for Water‐Based and Tunable Nanostructure Templating of Printed Titania Thin Films: The Influence of pH Value and Protein Concentration

AbstractAn environmentally friendly as well as scalable synthesis route of nanostructured titania thin films is of interest for many state‐of‐the‐art devices, from solar cells to battery materials. Beta‐lactoglobulin (ß‐lg) enables water‐based and tunable titania thin film templating, allowing for different domain sizes, porosities, and morphologies. When printed with a slot‐die coater, the titania films can be tailored to specific applications with simple changes to the solution chemistry. Films printed at acidic pH conditions form significantly different final morphologies than films printed at a neutral pH value. The protein concentration plays a more limited role in the final nanostructure. With in situ grazing incidence small‐angle/wide‐angle X‐ray scattering (GISAXS/GIWAXS), the structure formation is followed with an excellent time resolution during the printing process. From the GISAXS measurements, the size evolution of the titania clusters is understood, showing significant differences for different pH values. Crystal phases and corresponding crystal orientations are investigated with GIWAXS. The combination of a water‐based titania synthesis with the scalable film deposition via slot die coating makes the presented results interesting for potential environmentally friendly mass production of nanostructured titania films.

Patterns and Practices in the Use of Endodontic Materials: Insights from Romanian Dental Practices

The success of endodontic treatment depends on the correct use of materials during the cleaning and filling of the root canal system. The field of endodontics is constantly evolving with the introduction of new procedures and materials. Despite the continuous development of a wide range of chemical solutions and the introduction of new materials in endodontics, driven by the advances in state-of-the-art technologies, there is still a lack of data on how these advances are adapted to the daily practice of Romanian dentists in this field. The aim of this cross-sectional questionnaire-based study was the evaluation of current trends in endodontic practice, focusing on the materials used by dentists throughout Romania, performed by a number of dentists who graduated from universities in the Northern, Southern, Eastern, Western, and Central zones of Romania. The questions were about the irrigants used, the interim medication, the type of sealant, the filling technique, and the number of endodontic treatment sessions. The majority of participants in the research were general practitioners and endodontists, with some dentists of different specialties performing endodontic treatments in their practices. Statistical analyses were performed using DATAtab version 2024 software. The results obtained from this study provide a valuable resource and database for researchers to access a wide range of information and an apparent trend towards high-performance endodontic materials used in Romania.

Complex Refractive Index Spectrum of CsPbBr3 Nanocrystals via the Effective Medium Approximation

We have estimated the intrinsic complex refractive index spectrum of a CsPbBr3 nanocrystal. With various dilute solutions of CsPbBr3 nanocrystals dissolved in toluene, effective refractive indices were measured at two different wavelengths using Michelson interferometry. Given the effective absorption spectrum of the solution, a full spectrum of the effective refractive index was also obtained through the Kramers–Krönig relations. Based on the Maxwell–Garnett model in the effective medium approximation, the real and imaginary spectrum of the complex refractive index was estimated for the CsPbBr3 nanocrystal, and the dominant inaccuracy was attributed to the size inhomogeneity.

An experimental study on the synergic damage of chemical solutions and stress to coal

This paper investigates the impact of treatment with chemical solutions of varying pH values on the micro-macroscopic damage in coal samples under load, employing a combination of Small Angle X-ray Scattering (SAXS) experiments and uniaxial compression tests. The experimental results show that soaking coal samples in NaOH, HCl, and distilled water for 7 days leads to reductions in uniaxial compressive strength by 39.19%, 47.26%, and 24.39%, respectively, compared to untreated coal. The elastic modulus exhibited similar reductions, further confirming the weakening effects of chemical solutions. SAXS experiments reveal that exposure to alkaline solutions promotes the expansion and connection of nanopores, while acidic solutions primarily dissolve mineral components, increasing brittleness. Distilled water causes milder effects on pore structure and mechanical properties. To model the synergic effects of chemical solution corrosion and stress, a chemical solution corrosion-stress coupling factor was introduced into the Weibull probability distribution-based constitutive model. The modified model accurately describes the strain–stress behavior and damage evolution under combined chemical and mechanical effects. These findings highlight the risks of chemical solution-induced damage to coal and provide theoretical support for disaster prevention and stability control in coal mining.

Bifunctional Group Modulation Strategy Enables MR-TADF Electroluminescence Toward BT.2020 Green Light Standard.

Herein, a parallel "bifunctional group" modulation method is proposed to achieve controlled modulation of the emission wavelength and full-width at half-maximum (FWHM) values. As a result, three proof-of-concept emitters, namely DBNDS-TPh, DBNDS-DFPh, and DBNDS-CNPh, are designed and synthesized, with the first functional dibenzo[b,d]thiophene unit concurrently reducing the bandgap and elevate their triplet state energy. A second functional group 1,1':3',1″-triphenyl, and electron acceptors 1,3-difluorobenzene and benzonitrile, respectively, to deepen the HOMO and LUMO levels. Accordingly, the CIE coordinates of DBNDS-TPh, DBNDS-DFPh, and DBNDS-CNPh are (0.13, 0.77), (0.14, 0.77), and (0.14, 0.76) respectively, in a dilute toluene solution. This marks the first instance of achieving a CIEy value of 0.77 in dilute toluene solutions. Significantly, the non-sensitized pure-green OLEDs based on DBNDS-TPh and DBNDS-DFPh demonstrate peak EQE of 35.0% and 34.5%, with corresponding CIE coordinates of (0.18, 0.75), (0.17, 0.76) at the doping concentration of 1 wt.%, representing the first green OLED with a CIEy value reaching 0.76 in a bottom-emitting device structure as reported in the literature.

Dual-State Emissive Mitochondrial Viscosity Probe for Long-Term Imaging of Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is a destructive autoimmune disease that seriously affects human health. Due to the lack of a cure for RA, a good prognosis largely depends on early diagnosis and effective treatment monitoring of RA. Therefore, the development of fluorescent probes capable of real-time detection of RA is of great significance. Dual-state emission (DSE) molecules can emit light in both dilute solution and solid state, making them ideal fluorophores for constructing fluorescent probes. However, there are currently no reports of DSE molecule-based fluorescent probes for RA imaging. Herein, we report a fluorescent probe MQP-Boc based on a novel DSE molecule for effective RA imaging. MQP-Boc selectively responds to viscosity with sensitive fluorescence changes at 667 nm and is mitochondria targetable. Cell imaging studies show that MQP-Boc can detect changes in mitochondrial viscosity and perform long-term imaging of mitochondria, which is significantly superior to that of the control probe MQP-Ac. Imaging studies on a mouse model of RA induced by λ-carrageenan show that MQP-Boc has excellent real-time and long-term imaging capabilities for RA. Besides, with MQP-Boc, significant increases in joint tissue viscosity were found during the RA process. All results indicate that MQP-Boc is an effective new tool for studying and diagnosing RA.

Unraveling the Role of Polyoxometalates-Based Superchaotropes on the Photophysics of Organic Molecules and Modulation of Water Dynamics in a Hydrophilic Block Copolymer Solution.

Polyoxometalates (POMs) are composed of nanometric metal-oxide anions and have rich solution chemistry. In this class, Keggin POMs have been identified as the most influential inorganic additives for aqueous nonionic soft matter systems. POMs being at the borderline of classical ions and charged colloids possess fascinating solution properties; the present work aims to delve deeper into the interactions between nanoions and nonionic soft matters from a spectroscopic point of view. Our studies reveal that although of the same structural makeup, silicotungstic acid hydrate (SiW) and phosphotungstic acid hydrate (PW) affect the photophysics of Coumarin-480 (C-480) in poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) ((PEO)76-(PPO)30-(PEO)76, F-68) copolymeric media in a dissimilar manner. From time-resolved studies, we find a preference for SiW toward the intramolecular charge transfer state of C-480, whereas PW favors the locally emissive state of the probe. Further, from rotational relaxation studies, it appears that SiW renders a rigid environment around the probe molecule, while PW relaxes the copolymeric environment. Finally, the dynamic quenching mechanism of the added nanoions was unraveled, which showed a straightforward Förster mechanism for SiW but a short-range interaction was operative for PW. From Fourier transform infrared and 1H NMR, it can be concluded that both the nanoions interacted with the PPO moiety of the copolymer; yet, their contrasting effect on the photophysics has been rationalized as a consequence of charge density on the ions.

Analysis of the Impact of Deicing Salts on Transport Properties of Concrete – Preliminary Results

The ingress of deicing chemical solutions into the pore system of hardened concrete can profoundly affect its physical and chemical properties. It is a known fact that salt solutions are highly conductive in comparison with pure water and as a result when they penetrate into concrete they alter its electrical resistivity as well as other transport properties. In this study, the influence of three deicing salts on transport properties measured in four different ways: (1) surface resistivity (SR), (2) rapid chloride permeability (RCPT), (3) sorptivity, and (4) apparent chloride diffusion, of specimens exposed to sodium chloride, calcium chloride, and magnesium chloride is investigated. The feasibility of using these test methods to evaluate in service structures is discussed. It was observed that transport properties, measured by the several test methods, appear to be influenced by different factors when in presence of salts. There is a correlation between SR and RCPT, but in these preliminary results there is no good correlation between the other tests.

Stable Electrochemical Lithium Extraction Using LiMn2O4 Coated With Lithiated Nafion.

Electrochemical lithium extraction from salt lakes using LiMn2O4 (LMO) presents an eco-friendly, highly controllable, and efficient method. However, its practical application is limited due to its structure instability and manganese dissolution in water. Herein, a high-performance LMO coated with ≈3.5nm thickness lithiated Nafion (Li-Nafion) for electrochemical lithium extraction is reported. The Li-Nafion coating constructs a fast lithium-ion transport pathway and enhances the hydrophilicity of the LMO particles, promoting charge transfer and improving rate capability. Thereby, an enhanced lithium extraction capacity of 4mmolg-1 is achieved. Importantly, the coating significantly inhibits Mn loss in LMO, resulting in significantly improved cyclic stability, with a capacity retention rate of 96% after 50 cycles. Furthermore, the Li-Nafion modified LMO effectively extracts lithium electrochemically in Zabuye salt lake, showcasing practical potential.

(2-Dimesitylboryl)phenyl]ethynyl-Substituted [2.2]Paracyclophane Exhibiting Circularly Polarized Luminescence in Both Solution and Solid-State.

Developing a new type of circularly polarized luminescent active small organic molecule that combines high fluorescence quantum yield and luminescence dissymmetric factor in both solution and solid state is highly challenging but promising. In this context, we designed and synthesized a unique triarylborane-based [2.2]paracyclophane derivative, m-BPhANPh2-Cp, in which an electron-accepting [(2-dimesitylboryl)phenyl]ethynyl group and an electron-donating N,N-diphenylamino group are introduced into two different benzene rings of [2.2]paracyclophane. Owing to the electronic effect of these two substituents, this compound can display charge-transfer emission with large Stokes shifts (∆υ = 4.23 - 8.20 × 103 cm-1) and fair quantum yields (ΦF = 0.15 - 0.37) in solutions. In addition, this compound can emit strong blue fluorescence in the solid state with quantum yields that are even much higher than in solution (ΦF up to 0.64 in powder and spin-coated film). Moreover, the enantiomeric forms of m-BPhANPh2-Cp can show strong CPL signals in both dilute solution and solid state with |glum|s up to 9.6 × 10-3 and 5.4 × 10-3, respectively. Thus, it is possible to achieve tunable CPL from blue to yellow in solution with high BCPLs ranging from 56.7 to 26.6 M-1 cm-1 and intense blue CPL combing high ΦF and |glum| in the solid state.

Easy One-Pot Decoration of Graphene Oxide Nanosheets by Green Silver Nanoparticles.

In this study, we developed a facile one-pot synthesis of a nanocomposite consisting of silver nanoparticles (AgNPs) growing over graphene oxide (GO) nanoflakes (AgNPs@GO). The process consists of the in situ formation of AgNPs in the presence of GO nanosheets via the spontaneous decomposition of silver(I) acetylacetonate (Ag(acac)) after dissolution in water. This protocol is compared to an ex situ approach where AgNPs are added to a waterborne GO nanosheet suspension to account for any attractive interaction between preformed nanomaterials. The systems under investigation are characterized by UV/vis absorption spectroscopy, dynamic light scattering (DLS), zeta potential (Z-Pot), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX). The stability of the AgNPs@GO composite suspension is tested as a function of GO concentration (0-67 μg/mL) while maintaining a constant Ag content (14.4 μg/mL), exhibiting excellent stability over time up to an Ag-to-GO mass ratio of 0.58.

Computational Explorations of Th4+ First Hydrolysis Reaction Constants: Insights from Ab Initio Molecular Dynamics and Density Functional Theory Calculations.

The fundamental hydrolysis behavior of tetravalent actinide cations (An4+) with a high charge is crucial for understanding their solution chemistry, particularly in nuclear fuel reprocessing and environmental behavior. Using Th4+ as a reference of the An4+ series, this work employed both the periodic model and the cluster model to calculate the first hydrolysis reaction constant (pKa1) of the Th4+ aqua ion and conducted a detailed evaluation of these approaches. In the periodic model, ab initio molecular dynamics (AIMD) simulations of Th4+ in the explicit solvation environment are conducted, using metadynamics and constrained molecular dynamics to calculate pKa1 values. Metadynamics simulations with sufficient sampling yielded a value of 5.02, aligning with the experimental values (4.12-4.97). Moreover, AIMD results reveal further Grotthuss-type proton transfers and changes in the solvent structures, which are important for accurately modeling the hydrolysis process. In the cluster model, density functional theory calculations are performed on isolated hydrate clusters to obtain pKa1 values, describing solvation effects through the cluster-continuum model. Based on insights from the periodic models, particularly regarding further proton transfer, the cluster model was modified and tested using different functionals and similar cations (La3+and Ac3+). The pKa1 values obtained in the cluster model also show good agreement with the experimental values. The current computational approaches provide a comprehensive understanding of Th4+ hydrolysis and a reference framework for studying the hydrolysis of other lanthanide and actinide ions.

Effect of Chain Conformation on the Free Energy of Dilute Polymer Solutions: Monte Carlo Simulations and Perturbation Theory for the Second Virial Coefficient of Lennard–Jones Chains

Effect of Chain Conformation on the Free Energy of Dilute Polymer Solutions: Monte Carlo Simulations and Perturbation Theory for the Second Virial Coefficient of Lennard–Jones Chains

Viscoelastic Behavior of Aqueous Hydroxypropyl Cellulose Solutions Due to Entanglements.

Hydroxypropyl cellulose (HpC) forms a liquid crystalline phase and is thought to have a rod-like shape in aqueous solution. The viscoelastic behaviors of aqueous solutions of HpC samples with average molar substitution numbers (MS ∼ 3.8) and weight-average molar masses (Mw = 36-740 kg mol-1) were examined over a wide concentration (c) range, and the results were discussed based on a concept of rod particle suspension rheology. The c and Mw dependencies of viscoelastic parameters determined in the frequency range showing flow behavior, such as the zero-shear viscosity, the average relaxation time, and the steady-state compliance in the c range for HpC molecules to fully entangle, were considered by using the number density (ν = cNA/Mw, where NA is the Avogadro constant), the intrinsic viscosity, and the average rod particle length of HpC molecules determined via dilute solution properties. The obtained relationships were successfully understood with the rod particle suspension rheology.