Solution Research Articles

Forecasting vaping health risks through neural network model prediction of flavour pyrolysis reactions

Vaping involves the heating of chemical solutions (e-liquids) to high temperatures prior to lung inhalation. A risk exists that these chemicals undergo thermal decomposition to new chemical entities, the composition and health implications of which are largely unknown. To address this concern, a graph-convolutional neural network (NN) model was used to predict pyrolysis reactivity of 180 e-liquid chemical flavours. The output of this supervised machine learning approach was a dataset of probability ranked pyrolysis transformations and their associated 7307 products. To refine this dataset, the molecular weight of each NN predicted product was automatically correlated with experimental mass spectrometry (MS) fragmentation data for each flavour chemical. This blending of deep learning methods with experimental MS data identified 1169 molecular weight matches that prioritized these compounds for further analysis. The average number of discrete matches per flavour between NN predictions and MS fragmentation was 6.4 with 92.8% of flavours having at least one match. Globally harmonized system classifications for NN/MS matches were extracted from PubChem, revealing that 127 acute toxic, 153 health hazard and 225 irritant classifications were predicted. This approach may reveal the longer-term health risks of vaping in advance of clinical diseases emerging in the general population.

Characterization of electrokinetic and membrane properties of nanoporous polyimide films via measurements of time-resolved pressure-induced potential

Charged nanoporous films have interesting ion-separation properties essentially controlled by pore-surface charge density. This (or a related zeta-potential) is often estimated from the so-called streaming potential. However, with nanoporous membranes in sufficiently dilute electrolyte solutions, the pressure-induced electrical response is due not only to streaming potential but also to an electrical response to concentration gradients arising because of a partial salt rejection by charged nanopores. In this study, we refine the methodology of interpretation of measurements of transient filtration potential developed by us previously and apply it to the determination of electrokinetic and membrane properties (in particular, diffusion permeance) of nanoporous polyimide films developed for uses as battery/supercapacitor separators. Diffusion permeance is directly related to electrical conductance, which is an important property of battery/supercapacitor separators.We observe that in dilute electrolyte solutions (<2 mM KCl), the electrical response to an applied pressure difference is dominated by the concentration potential and not by the classical streaming potential contrary to what is often tacitly assumed. The development of concentration gradients across and around the film takes some time, which enables separate determination of instantaneous (streaming potential) and time-delayed (concentration potential) components. An improved interpretation procedure developed in this study enables estimates of impact of non-linear and osmotic corrections and makes the interpretation more reliable. The results of this study are important for the identification and optimization of novel innovative applications for nanoporous films.

Towards Modelling Mechanical Shaking Using Potential Energy Surfaces: A Toy Model Analysis

In this work, we formalize the effect of mechanical shaking by using various forms of an externally exerted force, which may be constant or may be position-dependent, and we examine the changes in the potential energy surfaces that quantify the chemical reaction. We use a simple toy model to model the potential energy surfaces of a chemical reaction, and we study the effect of a constant or position-dependent externally exerted force for various forms of the force. As we demonstrate, the effect of the force can be quite dramatic on the potential energy surfaces, which acquire new stationary points and new Newton trajectories that are distinct from the original ones that were obtained in the absence of mechanochemical effects. We also introduce a new approach to mechanochemical interactions, using a dynamical systems approach for the Newton trajectories. As we show, the dynamical system attractor properties of the trajectories in the phase space are identical to the stationary points of the potential energy surfaces, but the phase space contains much more information regarding the possible evolution of the chemical reaction—information that is quantified by the existence of unstable or saddle fixed points in the phase space. We also discuss how an experimental method for a suitable symmetric liquid solution substance might formalize the effect of shaking via various forms of external force, even in the form of an extended coordinate-dependent force matrix. This approach may experimentally quantify the Epstein effect of shaking in chemical solutions via mechanochemistry methods.

CHIRAL SWITCHING CONTROL OF PHARMACEUTICAL SUBSTANCES

Objective: The aim of this study was to demonstrate that chiral switching should be recognized as a widespread phenomenon that extends beyond the production of pure enantiomeric drugs. Methods: To investigate the optical activity of substances from various chemical classes, enantiomers of chiral compounds (Sigma-Aldrich, USA) were chosen: valine and its racemic form (D-valine, L-valine, and racemic valine with optical purity ≥ 99%), L-ascorbic acid (content ≥ 99%), carbohydrates (D-glucose, D-galactose, L-galactose, contents ≥ 99.5%). Solutions were prepared using deuterium-depleted water (DDW–"light" water, D/H=4 ppm), natural deionized high-ohmic water (BD, D/H=140 ppm), and heavy water (99.9% D2O; Sigma-Aldrich). Optical activity was measured using the Atago POL-1/2 polarimeter. Results: One of the components in the racemic medication mixture can act as an inert agent, exhibit toxicity, or undergo undesirable biotransformation mechanisms, resulting in the formation of products with unknown properties. It has been established that a change in the deuterium/protium (D/H) ratio in water leads to a change in the equilibrium and kinetic characteristics of optically active compounds across various chemical classes, such as amino acids, carboxylic acids, and carbohydrates. An inequality was observed in the absolute values of the optical rotation of the L-and D-isomers of valine and galactose, depending on the D/H isotope ratio. The impact of chiral water clusters on optical rotation accounts for the sudden shift in the specific rotation of dilute solutions (less than 0.5%) of L-ascorbic acid in water, based on the D/H ratio. The influence of the isotopic composition of water was confirmed by studying the temperature-dependent mutarotation kinetics of D-glucose and L-and D-galactose in Arrhenius coordinates. The mutarotation process in natural high-resistivity water is characterized by an activation energy (Ea) of 40.8±1.4 kJ mol-1, while in deuterium-depleted water, Ea = 63.6±3.5 kJ mol-1. This results in a kinetic isotope effect for deuterium (KIED) of 1.6. Conclusion: Methodological approaches have been developed to control chiral switching based on the isotopic composition of water in vivo and in vitro. The study of changes in the optical activity of hierarchical structures in the human body, the influence of solvent properties on the mechanisms of optical rotation, as well as the use of KIED values, can be utilized to monitor various chiral transitions in vitro and living organisms.

Dynamics of Single-Chain Nanoparticles under Crowding: A Neutron Spin Echo Study.

We present a neutron spin echo (NSE) investigation to examine the impact of macromolecular crowding on the dynamics of single-chain nanoparticles (SCNPs), serving as synthetic models for biomacromolecules with flexibility and internal degrees of freedom, such as intrinsically disordered proteins (IDPs). In particular, we studied the dynamics of a medium-size poly(methyl methacrylate) (PMMA)-based SCNP (33 kDa) in solutions with low- (10 kDa) and high- (100 kDa) molecular weight analogous deuterated PMMA linear crowders. The dynamic structure factors of the SCNPs in dilute solution show certain degrees of freedom, yet the analysis in terms of the Zimm model reveals high internal friction that effectively stiffens the chain-a phenomenon also observed for IDPs. Under crowding conditions, the internal dynamics remains essentially unchanged, but the center-of-mass diffusion slows down. The effective viscosity felt by the SCNPs at the timescales probed by NSE is lower than the macroscopic viscosity of the crowder solution, and it does not depend significantly on the molecular weight.

Diffusion Dynamics of Star-Shaped Macromolecules in Dilute Solutions

Diffusion Dynamics of Star-Shaped Macromolecules in Dilute Solutions

Enhancement of ferroelectricity in chemical-solution-deposited ZrO2 thin films through fine phase transition control

Recent studies have highlighted the ferroelectric potential of ZrO2 thin films, which offer advantages over HfO2-based ferroelectric materials, such as lower thermal budget and greater natural abundance. In this research, pure ZrO2 ferroelectric thin films were fabricated on Si substrates using chemical solution deposition with all-inorganic precursors. We explored the impacts of film thickness and HfO2 seed layers on phase transition and ferroelectric properties. Notably, an 11 nm thick ZrO2 film exhibited ferroelectric behavior with a remanent polarization of 12.6 μC/cm2. Due to the combined effects of tensile stress and surface energy, the increase in thickness to 30 nm led to a phase transition from the orthorhombic phase to the monoclinic phase and a resultant decrease in remanent polarization. Additionally, the introduction of a HfO2 seed layer facilitated the crystallization of the ferroelectric o-phase, enhancing the remanent polarization to 16.5 μC/cm2 in our ∼8 nm thick ZrO2 thin film with a ∼2 nm thick HfO2 seed layer. These findings provide valuable insights into optimizing ferroelectric properties in ZrO2 thin films through phase transition control.

In-Situ Ultrafast Construction of Zinc Tungstate Interface Layer for Highly Reversible Zinc Anodes.

Constructing artificial solid electrolyte interface on the Zn anode surface is recognized as an appealing method to inhibit zinc dendrites and side reactions, whereas the current techniques are complex and time-consuming. Here, a robust and zincophilic zinc tungstate (ZnWO4) layer has been in situ constructed on the Zn anode surface (denoted as ZWO@Zn) by an ultrafast chemical solution reaction. Comprehensive characterizations and theoretical calculations demonstrate that the ZWO layer can effectively modulate the interfacial electric field distribution and promote the Zn2+ uniform diffusion, thus facilitating the uniform Zn2+ nucleation and suppressing zinc dendrites. Besides, ZWO layer can prevent direct contact between the Zn/water and increase the hydrogen evolution reaction overpotential to eliminate side reactions. Consequently, the in situ constructed ZWO layer facilitates remarkable reversibility in the ZWO@Zn||Ti battery, achieving an impressive Coulombic efficiency of 99.36 % under 1.0 mA cm-2, unprecedented cycling lifespan exceeding 1800 h under 1.0 mA cm-2 in ZWO@Zn||ZWO@Zn battery, and a steady and reliable operation of the overall ZWO@Zn||VS2 battery. The work provides a simple, low cost, and ultrafast pathway to crafting protective layers for driving advancements in aqueous zinc-metal batteries.

From flat to folded: An instrument-free solution for chemical and biological paper-based sensing using A-PAP pen technology

Having economical, flexible, disposable and readily manufacturable devices for everyday sensing applications is of paramount importance. We report a novel and cost-effective technique for fabricating paper-based devices using an Advanced PAP (A-PAP) pen, which is capable of withstanding typical aqueous solutions and organic solvents. The quick fabrication process does not require any sophisticated instrumentation or a heating step, making it a promising technology for resource-limited settings. Using an A-PAP pen, we have fabricated two-dimensional (2D) paper-based devices for chemical detection of heavy metal and nitrite. We have also demonstrated the versatility of fabrication technique for biological sensing using 2D lateral flow paper-based devices for the detection of dopamine. Furthermore, the technique is also validated for fabricating complex three-dimensional (3D) paper-based devices using a paper origami technique for heavy metals sensing. The ready-to-use devices can be fabricated in seconds, making them convenient for on-the-spot testing. Overall, this technique provides a valuable tool for creating affordable, efficient, and accessible chemical and biological testing solutions.

Are Clay Minerals Systematically the Products of Aqueous Alteration in Cosmic Bodies?

The formation of chondrite materials represents one of the earliest mineralogical processes in the solar system. Phyllosilicates are encountered at various stages of the chondrule formation, from the initial stages (IDP agglomerates) to the final steps (chondrule internal alteration). While typically linked to aqueous alteration, recent studies reveal that phyllosilicates could precipitate directly from residual fluids in post-magmatic or deuteric conditions and under a wide range of temperatures, pressures, water/rock ratios, and H2/H2O ratio conditions. This study re-examined the formation of hydrated phyllosilicates in chondrules and associated fine-grained rims (FGRs) using published petrographical, mineralogical, and chemical data on carbonaceous chondrites. Given that chondrules originate from the melting of interplanetary dust particles, the water liberated by the devolatilization of primary phyllosilicates, including clay minerals or ice melting, reduces the melting temperature and leads to water dissolution into the silicate melt. Anhydrous minerals (e.g., olivine and diopside) form first, while volatile and incompatible components are concentrated in the residual liquid, diffusing into the matrix and forming less porous FGRs. Serpentine and cronstedtite are the products of thermal metamorphic-like mineral reactions. The mesostasis in some lobated chondrules is composed of anhydrous and hydrous minerals, i.e., diopside and serpentine. The latter is probably not the alteration product of a glassy precursor but rather a symplectite component (concomitant crystallization of diopside and serpentine). If so, the symplectite has been formed at the end of the cooling process (eutectic-like petrographical features). Water trapped inside chondrule porosity can lead to the local replacement of olivine by serpentine without external water input (auto-alteration). In the absence of water, hydrated phyllosilicates do not crystallize, forming a different mineral assemblage.

Illuminating the problem of blue verditer synthesis in the early modern English period: chemical characterisation and mechanistic understanding

We present a study into early modern English production of blue verditer, an early synthetic copper-based blue pigment chemically analogous to azurite. Verditers have been identified in numerous wall and easel paintings. While initial documentation occurs in the mid 1500s and production recipes were documented by the 17th c., the synthesis was known to be unreliable. This study replicates historical and recent scientific work on blue verditer and represents a significant advance in our understanding of verditer production and its challenges. Procedures for verditer synthesis are drawn from both 17th c. documentation and 20th c. replication work. The effects of temperature, copper and carbonate sources, solution stirring, copper ion concentration, and atmospheric composition are studied in order to elucidate the mechanism of synthesis and explain its unreliability in early modern refineries. Products are characterised by polarised light microscopy, scanning electron microscopy, Raman spectroscopy, and powder X-Ray diffraction. Rouaite, a green basic copper nitrate, is for the first time confirmed as a product of the refiners’ synthesis and a precursor to blue verditer in laboratory syntheses. This result problematises the blanket identification of green verditer as basic copper carbonate and provides important clues to the mechanism for blue verditer synthesis. Solution chemistry and ion equilibria allow us to explain the route by which rouaite is first formed and then converted to blue verditer. Conditions favouring blue verditer production are also clarified further. Although it is commonly stated that low temperatures are required for blue verditer production, blue verditer is produced here at a range of ambient temperatures. The reaction is found instead to be controlled by solution equilibria and heavily favoured by high partial pressures of carbon dioxide. Alongside archival materials about refining and verditer production, these results are contextualised and explanations for the unreliability of historical synthesis are proposed.

The synergistic effect of typical chiral organic acids and solution chemistry conditions on the transport of 2-arylpropionic acid chiral derivatives in porous media

The hazards of man-made chiral compounds are of great public concern, with reports of worrying stereoselective compounds and an urgent need to assess their transport. This study evaluated the transport of 2-arylpropionic acid derivatives enantiomers (2-APA) in porous media under a variety of solution chemistry conditions via column packing assays. The results revealed the introduction of Malic acid (MA) enantiomers enhanced the mobility of 2-APA enantiomers, but the enhancement effect was different for different 2-APA enantiomers. Batch sorption experiments confirmed that the MA enantiomers occupied the sorption site of the quartz sand, thus reducing the deposition of the 2-APA enantiomer. Homo- or heterochirality between 2-APA and MA dominates the transport of 2-APA enantiomers, with homochirality between them triggering stronger retention and vice versa. Further evaluating the effect of solution chemistry conditions on the transport of 2-APA enantiomers, increased ionic strength attenuated the mobility of 2-APA enantiomers, whereas introduced coexisting cations enhanced the retention of 2-APA enantiomers in the column. The redundancy analyses corroborated these solution chemistry conditions were negatively correlated with the transport of 2-APA enantiomers. The coupling of pH and these conditions reveals electrostatic forces dominate the transport behavior and stereoselective interactions of 2-APA enantiomers. Distinguishing the transport of enantiomeric pair helps to understand the difference in stereoselectivity of enantiomers and promises to remove the more hazardous one.

A Study on the Effect of Dilution on Refractive Index of Acetone

This r study investigates the impact of dilution on the refractive index of acetone-water solutions, aiming to study the relationship between solution concentration and optical properties. The experiment involves preparing a series of acetone-water solutions with varying concentrations and measuring their refractive indices using a spectrometer. The abstract will outline the methodology employed, including the preparation of solutions, experimental setup, and data collection procedures. It will also highlight the use of refractive index measurements in describing the characteristics of solutions and their applicability in physics, chemistry, and materials science. The study's expected findings, including the possibility of departures from ideal behaviour and the relationship between solution concentration and refractive index, will be covered in the abstract. It will also stress how crucial it is to understand how dilution affects refractive index for real-world uses, like those in the food, chemical, and pharmaceutical sectors. A greater understanding of solution chemistry and optical phenomena will result from this research's insightful observations of the optical behaviour of acetone-water solutions. Key Words: optics, spectrometer, refractive index, acetone

Special Issue on IUPAC 38th Edition of the International Conference on Solution Chemistry

Special Issue on IUPAC 38th Edition of the International Conference on Solution Chemistry

Polymer Coatings Affect Transport and Remobilization of Colloidal Activated Carbon in Saturated Sand Columns: Implications for In Situ Groundwater Remediation.

Colloidal activated carbon (CAC) is an emerging technology for the in situ remediation of groundwater impacted by per- and polyfluoroalkyl substances (PFAS). In assessing the long-term effectiveness of a CAC barrier, it is crucial to evaluate the potential of emplaced CAC particles to be remobilized and migrate away from the sorptive barrier. We examine the effect of two polymer stabilizers, carboxymethyl cellulose (CMC) and polydiallyldimethylammonium chloride (PolyDM), on CAC deposition and remobilization in saturated sand columns. CMC-modified CAC showed high mobility in a wide ionic strength (IS) range from 0.1 to 100 mM, which is favorable for CAC delivery at a sufficient scale. Interestingly, the mobility of PolyDM-modified CAC was high at low IS (0.1 mM) but greatly reduced at high IS (100 mM). Notably, significant remobilization (release) of deposited CMC-CAC particles occurred upon the introduction of solution with low IS following deposition at high IS. In contrast, PolyDM-CAC did not undergo any remobilization following deposition due to its favorable interactions with the quartz sand. We further elucidated the CAC deposition and remobilization behaviors by analyzing colloid-collector interactions through the application of Derjaguin-Landau-Verwey-Overbeek theory, and the inclusion of a discrete representation of charge heterogeneity on the quartz sand surface. The classical colloid filtration theory was also employed to estimate the travel distance of CAC in saturated columns. Our results underscore the roles of polymer coatings and solution chemistry in CAC transport, providing valuable guidelines for the design of in situ CAC remediation with maximized delivery efficiency and barrier longevity.

Preliminary studies for the removal of carbonate deposits from painted ceramics using chemical solutions

Preliminary studies for the removal of carbonate deposits from painted ceramics using chemical solutions

Plant polysaccharide-derived edible film packaging for instant food: Rapid dissolution in hot water coupled with exceptional mechanical and barrier characteristics

A comprehensive multiscale analysis was conducted to explore the effects of different ratios of these materials on its properties. The results show that KC played a crucial role in controlling solution viscosity and gel and sol temperatures. The dissolution time at high water temperatures primarily decreased with an increase in SA content. Higher KC and CS content increased tensile strength (TS) and elongation at break (ε), while also exhibiting better thermal stability. Water vapor transmission (WVT) and permeability (PV) initially decreased, then increased with the increase of SA and CS contents. Finally, an SA:KC:CS ratio of 1:3:2 showed optimal comprehensive properties, with a dissolution time of about 60.0 ± 3.8 s, TS of 23.80 ± 0.29 MPa, ε of 18.61 ± 0.34 %, WVT of 21.74 ± 0.62 g/m2·24h, and PV of 5.39 ± 0.17 meq/kg. Meanwhile, the SA:KC:CS edible food packaging only introduced minimal effects on food after dissolution, and the total bacterial count met regulatory standards.

Isocompositional liquid-liquid transition in dilute aqueous LiCl solutions

We here demonstrate that small amounts of LiCl dissolved in water extend the existence window of deeply supercooled liquid water. This shift allows us to observe the isocompositional, sharp liquid-liquid transition (LLT), while this is not possible in pure water. Upon heating at ambient pressure, the hyperquenched and densified glass first turns into the high-density liquid (HDL) and then experiences the LLT to the low-density liquid (LDL) at 137–141 K and ambient pressure. At the LLT the viscosity suddenly jumps up by an order of magnitude, from ∼4.3×109Pas in HDL to ∼3.7×1010Pas in LDL for the 3.1 mol % solution based on our calorimetric analysis. That is, the LLT takes place clearly in the ultraviscous liquid domain at ambient pressure. By contrast, the viscosity of the emerging LDL at the LLT is still in the domain of the soft glass for pure water and for solutions exceeding 5 mol % LiCl that were studied in the past. This is owing to our observation that, first, the LDL's glass transition is lowered by about 8 K to 126 K in the presence of small amounts LiCl, whereas the HDL's glass transition remains at 118 K. Second, the stability of HDL at ambient pressure is increased by high-pressure annealing, shifting the LLT to higher temperatures. Published by the American Physical Society 2024

Hydrophobic CHA-ZIFs with a junctional trap between cha and d6r cages for adsorption of 2,3-butanediol in aqueous solution

Hydrophobic CHA-ZIFs with a junctional trap between cha and d6r cages for adsorption of 2,3-butanediol in aqueous solution

Enhancement of waterborne pathogen removal by functionalized biochar with ε-polylysine ″dynamic arms″: Potential application in ultrafiltration system

Widespread outbreaks of threatening infections caused by unknown pathogens and water transmission have spawned the development of adsorption methods for pathogen elimination. We proposed a biochar functionalization strategy involving ε-polylysine (PLL), a bio-macromolecular poly(amino acid)s with variable folding conformations, as a "pathogen gripper" on biochar. PLL was successfully bridged onto biochar via polydopamine (PDA) crosslinking. The extension of electropositive side chains within PLL enables the capture of both nanoscale viruses and micrometer-scale bacteria in water, achieving excellent removal performances. This functionalized biochar was tentatively incorporated into ultrafiltration (UF) system, to achieve effective and controllable adsorption and retention of pathogens, and to realize the transfer of pathogens from membrane surface/pore to biochar surface as well as flushing water. The biochar-amended UF systems presents complete retention (∼7 LRV) and hydraulic elution of pathogens into membrane flushing water. Improvements in removal of organics and anti-fouling capability were observed, indicating the broken trade-off in UF pathogen removal dependent on irreversible fouling. Chemical characterizations revealed adsorption mechanisms encompassing electrostatic/hydrophobic interactions, pore filling, electron transfer, chemical bonding and secondary structure transitions. Microscopic and mechanical analyses validated the mechanisms for rapid adsorption and pathogen lysis. Low-concentration alkaline solution for used biochar regeneration, facilitated the deprotonation and transformation of PLL side chain to folded structures (α-helix/β-sheet). Biochar regeneration process also promoted the effective detachment/inactivation of pathogens and protection of functional groups on biochar, corroborated by physicochemical inspection and molecular dynamics simulation. The foldability of poly(amino acid)s acting like dynamic arms, significantly contributed to pathogen capture/desorption/inactivation and biochar regeneration. This study also inspires future investigation for performances of UF systems amended by poly(amino acid)s-functionalized biochar under diverse pressure, temperature, reactive oxygen species of feeds and chemical cleaning solutions, with far-reaching implications for public health, environmental applications of biochar, and UF process improvement.